Patent Publication Number: US-2018051778-A1

Title: Speed change device

Description:
TECHNICAL FIELD 
     The present disclosure relates to a speed change device that transfers power, which has been transferred to an input member, to an output member with the speed of the power changed. 
     BACKGROUND ART 
     There has hitherto been known a speed change device to be mounted on a vehicle, the speed change device including a double-pinion type first planetary gear mechanism, a Ravigneaux type second planetary gear mechanism, and four clutches C 1 , C 2 , C 3 , and C 4 , two brakes B 1  and B 2 , and a one-way clutch F  1  that change a power transfer path from the input side to the output side (see Patent Document 1, for example). With the speed change device, first to eighth forward speeds and first and second reverse speeds can be established by selectively engaging two of the clutches C 1  to C 4  and the brakes B 1  and B 2 . In addition, there has hitherto been known a device that includes a single-pinion type first planetary gear mechanism, a Ravigneaux type second planetary gear mechanism, and three clutches C 1 , C 2 , and C 3 , two brakes B 1  and B 2 , and a one-way clutch F  1  that change a power transfer path from the input side to the output side (see Patent Document 2, for example). With the speed change device, first to sixth forward speeds and a reverse speed can be established by selectively engaging two of the clutches C 1  to C 3  and the brakes B 1  and B 2 . Furthermore, there has hitherto been known a speed change device that is lightweight and compact, the speed change device including a Ravigneaux type planetary gear mechanism, and three clutches C 1 , C 2 , and C 3 , two brakes B 1  and B 3 , and a one-way clutch F  1  that change a power transfer path from the input side to the output side (see Patent Document 3, for example). With the speed change device, first to fourth forward speeds and a reverse speed can be established by selectively engaging two of the clutches C 1  to C 3  and the brakes B 1  and B 3 . 
     RELATED-ART DOCUMENTS 
     Patent Documents 
     [Patent Document 1] Japanese Patent Application Publication No. 2013-204754 (JP 2013-204754 A) 
     [Patent Document 2] Japanese Patent Application Publication No. 2010-038168 (JP 2010-038168 A) 
     [Patent Document 3] Japanese Patent Application Publication No. 2010-216568 (JP 2010-216568 A) 
     SUMMARY 
     Although the speed change device described in Patent Document 1 mentioned above can provide first to eighth forward speeds, it is desirable to provide a larger number of shift speeds in order to further improve the fuel efficiency and the drivability of a vehicle. Similarly, in the speed change devices described in Patent Documents 2 and 3, it is possible to improve the fuel efficiency and the drivability of a vehicle by increasing the number of shift speeds. 
     In view of the foregoing, it is a main object according to the present disclosure to provide a speed change device that is capable of improving the fuel efficiency and the drivability of a vehicle. 
     The present disclosure provides a speed change device that includes an input member, an output member, a composite planetary gear mechanism that has at least four rotary elements including an output element, and at least five engagement elements that each connect and disconnect one of the rotary elements of the composite planetary gear mechanism and a different one of rotary elements including the input member or a stationary member to and from each other, the speed change device transferring power, which has been transferred to the input member, to the output member with a speed of the power changed. The speed change device includes: a first gear train that includes a first drive gear always coupled to the output element of the composite planetary gear mechanism and a first driven gear which is always coupled to the output member and to which power is transferred from the first drive gear; a second gear train that includes a second drive gear always coupled to one of the rotary elements, not the output element, of the composite planetary gear mechanism and a second driven gear that is rotated in the same direction as the first driven gear by power from the second drive gear, the second gear train having a gear ratio that is different from that of the first gear train; and an output-side engagement element that connects and disconnects the second driven gear and the output member to and from each other. 
     In such a speed change device, when the output member is rotated with the output-side engagement element engaged, one of the rotary elements that is coupled via the second drive gear to the second driven gear which is rotated together with the output member is rotated with respect to the output member at a rotational speed that matches the gear ratio of the second gear train. When the output member is rotated with the output-side engagement element engaged, in addition, the output element of the composite planetary gear mechanism is rotated with respect to the output member at a rotational speed that matches the gear ratio of the first gear train. Thus, a rotational speed difference that matches the gear ratios of the first and second gear trains can be caused between the output element of the composite planetary gear mechanism and one of the rotary elements by engaging one of the at least five engagement elements and the output-side engagement element. Consequently, with the speed change device according to the present disclosure, it is possible to establish shift speeds other than those obtained by selectively engaging at least two of the at least five engagement elements. For example, in the case where power from the input member side is selectively transferred to a rotary element, not the output element, of the composite planetary gear mechanism, at least three shift speeds can be added to the speed change device to which the first and second gear trains and the output-side engagement element have not been added. As a result, with the speed change device according to the present disclosure, it is possible to further improve the fuel efficiency and the drivability of a vehicle by increasing the number of shift speeds. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to a first embodiment of the present disclosure. 
         FIG. 2  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to an input rotational speed of the speed change device of  FIG. 1 . 
         FIG. 3  is an operation table illustrating the relationship between each shift speed of the speed change device of  FIG. 1  and the respective operating states of clutches and brakes. 
         FIG. 4  is another operation table illustrating the relationship between each shift speed of the speed change device according to the first embodiment and the respective operating states of clutches and brakes. 
         FIG. 5  is still another operation table illustrating the relationship between each shift speed of the speed change device according to the first embodiment and the respective operating states of clutches and brakes. 
         FIG. 6  is another operation table illustrating the relationship between each shift speed of the speed change device according to the first embodiment and the respective operating states of clutches and brakes. 
         FIG. 7  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to a modified aspect of the first embodiment. 
         FIG. 8  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to another modified aspect of the first embodiment. 
         FIG. 9  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to still another modified aspect of the first embodiment. 
         FIG. 10  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to an input rotational speed of the speed change device of  FIG. 9 . 
         FIG. 11  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to another modified aspect of the first embodiment. 
         FIG. 12  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to still another modified aspect of the first embodiment. 
         FIG. 13  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to a second embodiment of the present disclosure. 
         FIG. 14  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to an input rotational speed of the speed change device of  FIG. 13 . 
         FIG. 15  is an operation table illustrating the relationship between each shift speed of the speed change device of  FIG. 13  and the respective operating states of clutches and brakes. 
         FIG. 16  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to a modified aspect of the second embodiment. 
         FIG. 17  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to another modified aspect of the second embodiment. 
         FIG. 18  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to still another modified aspect of the second embodiment. 
         FIG. 19  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to an input rotational speed of the speed change device of 
         FIG. 18 . 
         FIG. 20  is an operation table illustrating the relationship between each shift speed of the speed change device of  FIG. 18  and the respective operating states of clutches and brakes. 
         FIG. 21  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to another modified aspect of the second embodiment. 
         FIG. 22  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to still another modified aspect of the second embodiment. 
         FIG. 23  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to another modified aspect of the second embodiment. 
         FIG. 24  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to an input rotational speed of the speed change device of 
         FIG. 23 . 
         FIG. 25  is an operation table illustrating the relationship between each shift speed of the speed change device of  FIG. 23  and the respective operating states of clutches and brakes. 
         FIG. 26  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to still another modified aspect of the second embodiment. 
         FIG. 27  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to another modified aspect of the second embodiment. 
         FIG. 28  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to an input rotational speed of the speed change device of  FIG. 27 . 
         FIG. 29  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to still another modified aspect of the second embodiment. 
         FIG. 30  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to another modified aspect of the second embodiment. 
         FIG. 31  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to a third embodiment of the present disclosure. 
         FIG. 32  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to an input rotational speed of the speed change device of 
         FIG. 31 . 
         FIG. 33  is an operation table illustrating the relationship between each shift speed of the speed change device of  FIG. 31  and the respective operating states of clutches and brakes. 
         FIG. 34  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to a modified aspect of the third embodiment. 
         FIG. 35  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to another modified aspect of the third embodiment. 
         FIG. 36  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to still another modified aspect of the third embodiment. 
         FIG. 37  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to another modified aspect of the third embodiment. 
         FIG. 38  is a diagram illustrating a schematic configuration of a power transfer device that includes a speed change device according to a modified aspect of the first embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, an embodiment according to the present disclosure will be described with reference to the drawings. 
       FIG. 1  is a diagram illustrating a schematic configuration of a power transfer device  10  that includes an automatic transmission  20  which is a speed change device according to a first embodiment of the present disclosure. The power transfer device  10  illustrated in the drawing is connected to a crankshaft of an engine (internal combustion engine; not illustrated) and/or a rotor of an electric motor that serve as a drive source transversely mounted in the front portion of a front-wheel drive vehicle, and can transfer power (torque) from the engine or the like to left and right front wheels (drive wheels; not illustrated). As illustrated in the drawing, the power transfer device  10  includes a transmission case (stationary member)  11 , a starting device (fluid transmission apparatus)  12 , an oil pump  17 , and so forth in addition to the automatic transmission  20  which transfers power, which has been transferred from the engine or the like to an input shaft (input member)  20   i , to the front wheels of the vehicle with the speed of the power changed. 
     The starting device  12  includes a torque converter that has: a pump impeller  14   p  coupled to the drive source discussed above; a turbine runner  14   t  coupled to the input shaft  20   i  of the automatic transmission  20 ; a stator  14   s  disposed on the inner side of the pump impeller  14   p  and the turbine runner  14   t  to adjust a flow of working oil from the turbine runner  14   t  to the pump impeller  14   p ; a one-way clutch  14   o  that is supported by a stator shaft (not illustrated) and that restricts the rotational direction of the stator  14   s  to one direction; and so forth. The starting device  12  further includes: a lock-up clutch  15  that connects and disconnects a front cover coupled to the crankshaft of the engine or the like and the input shaft  20   i  of the automatic transmission  20  to and from each other; and a damper mechanism  16  that damps vibration between the front cover and the input shaft  20   i  of the automatic transmission  20 . The starting device  12  may include a fluid coupling that does not have the stator  14   s.    
     The oil pump  17  is constituted as a gear pump that has: a pump assembly that includes a pump body and a pump cover; an externally toothed gear (inner rotor) coupled to the pump impeller  14   p  of the starting device  12 ; an internally toothed gear (outer rotor) meshed with the externally toothed gear; and so forth. The oil pump  17  is driven by power from the engine or the like to suction working oil (ATF) reserved in an oil pan (not illustrated) and pump the working oil to a hydraulic control device (not illustrated). The externally toothed gear of the oil pump  17  may be coupled to the pump impeller  14   p  via a chain or a gear train. 
     The automatic transmission  20  is constituted as an 11-speed transmission. As illustrated in  FIG. 1 , the automatic transmission  20  includes, in addition to the input shaft  20   i : an output gear (output member)  20   o  disposed on a separate shaft (second shaft) that extends in parallel with the input shaft (first shaft)  20   i ; a Ravigneaux type planetary gear mechanism  25  that serves as a composite planetary gear mechanism constituted by combining a single-pinion type first planetary gear  21  and a double-pinion type second planetary gear  22  with each other; and a double-pinion type third planetary gear  23 . In the embodiment, the output gear  20   o  is an externally toothed gear, and is coupled to the left and right front wheels via a drive pinion gear meshed with the output gear  20   o , a differential gear that includes a differential ring gear meshed with the drive pinion gear, and a drive shaft (none of which is illustrated). In the embodiment, in addition, the first and second planetary gears  21  and  22 , which constitute the Ravigneaux type planetary gear mechanism  25 , and the third planetary gear  23  are disposed in the transmission case  11  so as to be arranged in the order of the third planetary gear  23 , the first planetary gear  21 , and the second planetary gear  22  from the starting device  12  side, that is, the engine side (the right side in  FIG. 1 ). 
     The Ravigneaux type planetary gear mechanism  25  has: a first sun gear  21   s  and a second sun gear  22   s  which are each an externally toothed gear; a first ring gear  21   r  which is an internally toothed gear disposed concentrically with the first sun gear  21   s ; a plurality of first pinion gears (long pinion gears)  21   p  meshed with the first sun gear  21   s  and the first ring gear  21   r ; a plurality of second pinion gears (short pinion gears)  22   p  meshed with the second sun gear  22   s  and the plurality of first pinion gears  21   p ; and a first carrier  21   c  that rotatably and revolvably holds the plurality of first pinion gears  21   p  and the plurality of second pinion gears  22   p.    
     The first sun gear  21   s , the first carrier  21   c , the first pinion gears  21   p , and the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  constitute the single-pinion type first planetary gear  21 . Meanwhile, the second sun gear  22   s , the first carrier  21   c , the first and second pinion gears  21   p  and  22   p , and the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  constitute the double-pinion type second planetary gear  22 . In the embodiment, the Ravigneaux type planetary gear mechanism  25  is configured such that a gear ratio λ 1  of the single-pinion type first planetary gear  21  (the number of teeth of the first sun gear  21   s /the number of teeth of the first ring gear  21   r ) is determined as λ 1 =0.458, for example, and a gear ratio λ 2  of the double-pinion type second planetary gear  22  (the number of teeth of the second sun gear  22   s /the number of teeth of the first ring gear  21   r ) is determined as λ 2 =0.375, for example. 
     Furthermore, a first drive gear  26  which is an externally toothed gear is always coupled coaxially with the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25 . The first ring gear  21   r  and the first drive gear  26  are always rotated and stopped together with each other. A first driven gear  27  which is an externally toothed gear is always coupled coaxially with the output gear  20   o  of the automatic transmission  20 . The first driven gear  27  is meshed with the first drive gear  26 , and always rotated and stopped together with the output gear  20   o . The first drive gear  26  and the first driven gear  27  to which power is transferred from the first drive gear  26  constitute a first gear train G 1 . The first ring gear  21   r  functions as an output element of the Ravigneaux type planetary gear mechanism  25 . 
     Additionally, a second drive gear  28  which is an externally toothed gear is always coupled coaxially with the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25 . The first carrier  21   c  and the second drive gear  28  are always rotated and stopped together with each other. The second drive gear  28  constitutes a second gear train G 2  together with a second driven gear (externally toothed gear)  29  meshed with the second drive gear  28 . The second gear train G 2  is configured such that a gear ratio gr 2  thereof (the number of teeth of the second driven gear  29 /the number of teeth of the second drive gear  28 ) is different from a gear ratio gr 1  of the first gear train G 1  (the number of teeth of the first driven gear  27 /the number of teeth of the first drive gear  26 ). In the embodiment, the gear ratio gr 1  of the first gear train G 1  is determined as gr 1 =1.00. Meanwhile, the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . In the embodiment, the gear ratio gr 2  is determined as gr 2 =0.870. 
     The third planetary gear  23  has: a third sun gear (stationary element)  23   s  which is an externally toothed gear; a third ring gear (output element)  23   r  which is an internally toothed gear disposed concentrically with the third sun gear  23   s ; and a third carrier  23   c  (input element) that rotatably and revolvably holds a plurality of sets of two pinion gears  23   pa  and  23   pb  meshed with each other. One of the pinion gears  23   pa  and  23   pb  is meshed with the third sun gear  23   s  and the other is meshed with the third ring gear  23   r . As illustrated in the drawing, the third sun gear  23   s  of the third planetary gear  23  is connected to (made stationary with respect to) the transmission case  11  via a support member (front support; not illustrated) so as to be non-rotatable. In addition, the third carrier  23   c  of the third planetary gear  23  is always coupled to the input shaft  20   i , and always rotated and stopped together with the input shaft  20   i . Consequently, the third planetary gear  23  functions as a so-called speed reduction gear, reduces the speed of power transferred to the third carrier  23   c  serving as an input element, and outputs the resultant power from the third ring gear  23   r  serving as an output element. In the embodiment, a gear ratio λ 3  of the third planetary gear  23  (the number of teeth of the third sun gear  23   s /the number of teeth of the third ring gear  23   r ) is determined as λ 3 =0.487, for example. 
     Furthermore, the automatic transmission  20  includes a clutch C 1  (third engagement element), a clutch C 2  (fourth engagement element), a clutch C 3  (fifth engagement element), a clutch C 4  (sixth engagement element), a brake B 1  (first engagement element), a brake B 2  (second engagement element), and a clutch C 5  (output-side engagement element), all of which are used to change a power transfer path from the input shaft  20   i  to the output gear  20   o.    
     The clutch C 1  connects and disconnects the third ring gear  23   r  of the third planetary gear  23  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The clutch C 2  connects and disconnects the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The clutch C 3  connects and disconnects the third ring gear  23   r  of the third planetary gear  23  and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The clutch C 4  connects and disconnects the third carrier  23   c  of the third planetary gear  23 , that is, the input shaft  20   i , and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  to and from each other. 
     The brake B 1  makes the first sun gear  21   s  (first securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to (connects the first sun gear  21   s  to) the transmission case  11  so as to be non-rotatable, and makes the first sun gear  21   s  non-stationary with respect to the transmission case  11 . The brake B 2  makes the second driven gear  29  of the second gear train G 2  stationary with respect to (connects the second driven gear  29  to) the transmission case  11  so as to be non-rotatable, and makes the second driven gear  29  non-stationary with respect to the transmission case  11 . When the second driven gear  29  of the second gear train G 2  is made stationary with respect to the transmission case  11  so as to be non-rotatable, the first carrier  21   c  (second securable element) of the Ravigneaux type planetary gear mechanism  25  which is coupled to the second driven gear  29  via the second drive gear  28  is connected to the transmission case  11  so as to be non-rotatable. The clutch C 5  connects and disconnects the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) to and from each other. 
     In the embodiment, a multi-plate friction-type hydraulic clutch (friction engagement element) is adopted as the clutches C 1 , C 2 , C 3 , C 4 , and C 5 . The multi-plate friction-type hydraulic clutch has a piston, a plurality of friction engagement plates (friction plates and separator plates), and a hydraulic servo constituted of an engagement oil chamber, a centrifugal hydraulic pressure cancellation chamber, etc. to which working oil is supplied. Meanwhile, a multi-plate friction-type hydraulic brake (friction engagement element) is adopted as the brakes B 1  and B 2 . The multi-plate friction-type hydraulic brake has a piston, a plurality of friction engagement plates (friction plates and separator plates), and a hydraulic servo constituted of an engagement oil chamber etc. to which working oil is supplied. The clutches C 1  to C 5  and the brakes B 1  and B 2  operate with working oil supplied thereto and discharged therefrom by the hydraulic control device. 
       FIG. 2  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to the rotational speed of the input shaft  20   i  (input rotational speed) of the automatic transmission  20  (note that the rotational speed of the input shaft  20   i , that is, the third carrier  23   c , is defined as a value of 1). In addition,  FIG. 3  is an operation table illustrating the relationship between each shift speed of the automatic transmission  20  and the respective operating states of the clutches C 1  to C 5  and the brakes B 1  and B 2 . 
     As illustrated in  FIG. 2 , the four rotary elements which constitute the Ravigneaux type planetary gear mechanism  25 , that is, the first sun gear  21   s  which serves as the first securable element, the first carrier  21   c  which serves as the second securable element, the first ring gear  21   r  which serves as the output element, and the second sun gear  22   s , are arranged, on the velocity diagram for the Ravigneaux type planetary gear mechanism  25  (the velocity diagram on the right side in  FIG. 2 ), in the order of the first sun gear  21   s , the first carrier  21   c , the first ring gear  21   r , and the second sun gear  22   s  from the left side of the drawing at intervals that match the gear ratio λ 1  of the single-pinion type first planetary gear  21  and the gear ratio λ 2  of the double-pinion type second planetary gear  22 . Here, according to the order of arrangement on the velocity diagram, the first sun gear  21   s  is defined as a first rotary element of the automatic transmission  20 , the first carrier  21   c  is defined as a second rotary element of the automatic transmission  20 , the first ring gear  21   r  is defined as a third rotary element of the automatic transmission  20 , and the second sun gear  22   s  is defined as a fourth rotary element of the automatic transmission  20 . Thus, the Ravigneaux type planetary gear mechanism  25  has the first rotary element, the second rotary element, the third rotary element, and the fourth rotary element of the automatic transmission  20  which are arranged sequentially at intervals that match the gear ratios λ 1  and λ 2  on the velocity diagram. 
     In addition, the three rotary elements which constitute the double-pinion type third planetary gear  23 , that is, the third sun gear (stationary element)  23   s , the third ring gear (output element)  23   r , and the third carrier  23   c  (input element), are arranged, on the velocity diagram for the third planetary gear  23  (the velocity diagram on the left side in  FIG. 2 ), in the order of the third sun gear  23   s , the third ring gear  23   r , and the third carrier  23   c  from the left side of the drawing at intervals that match the gear ratio λ 3 . Here, according to the order of arrangement on the velocity diagram, the third sun gear  23   s  is defined as a fifth rotary element of the automatic transmission  20 , the third ring gear  23   r  is defined as a sixth rotary element of the automatic transmission  20 , and the third carrier  23   c  is defined as a seventh rotary element of the automatic transmission  20 . Thus, the third planetary gear  23  has the fifth rotary element, the sixth rotary element, and the seventh rotary element of the automatic transmission  20  which are arranged sequentially at intervals that match the gear ratio λ 3  on the velocity diagram. 
     In the automatic transmission  20 , the clutches C 1  to C 5  and the brakes B 1  and B 2  are engaged and disengaged as illustrated in  FIG. 3  to change the relationship of connection of the first to seventh rotary elements discussed above, which allows establishing eleven power transfer paths in the forward rotational direction and two power transfer paths in the reverse rotational direction from the input shaft  20   i  to the output gear  20   o , that is, first to eleventh forward speeds and first and second reverse speeds. 
     Specifically, the first forward speed is established by engaging the clutch C 1  and the brake B 2  and disengaging the remaining clutches C 2  to C 5  and brake B 1 . That is, to establish the first forward speed, the third ring gear  23   r  (sixth rotary element) of the third planetary gear  23  and the second sun gear  22   s  (fourth rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the second driven gear  29  of the second gear train G 2 , that is, the first carrier  21   c  (second rotary element) which is coupled to the second driven gear  29  via the second drive gear  28 , is made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. In the embodiment (in the case where the gear ratios of the first to third planetary gears are determined as λ 1 =0.458, λ 2 =0.375, and λ 3 =0.487 and the gear ratios gr 1  and gr 2  of the first and second gear trains G 1  and G 2  are determined as gr 1 =1.00 and gr 2 =0.870; the same applies hereinafter), a gear ratio γ 1  of the first forward speed (the rotational speed of the input shaft  20   i /the rotational speed of the output gear  20   o ) is determined as γ 1 =5.200. 
     The second forward speed is established by engaging the clutch C 1  and the brake B 1  and disengaging the remaining clutches C 2  to C 5  and brake B 2 . That is, to establish the second forward speed, the third ring gear  23   r  of the third planetary gear  23  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. In the embodiment, a gear ratio γ 2  of the second forward speed is determined as γ 2 =2.971. In addition, the step ratio between the first forward speed and the second forward speed is determined as γ 1 /γ 2 =1.750. 
     The third forward speed is established by engaging the clutches C 1  and C 5  and disengaging the remaining clutches C 2  to C 4  and brakes B 1  and B 2 . That is, to establish the third forward speed, the third ring gear  23   r  of the third planetary gear  23  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . In the embodiment, a gear ratio γ 3  of the third forward speed is determined as γ 3 =2.374. In addition, the step ratio between the second forward speed and the third forward speed is determined as γ 2 /γ 3 =1.252. 
     The fourth forward speed is established by engaging the clutches C 1  and C 3  and disengaging the remaining clutches C 2 , C 4 , and C 5  and brakes B 1  and B 2 . That is, to establish the fourth forward speed, the third ring gear  23   r  of the third planetary gear  23  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the third ring gear  23   r  (sixth rotary element) of the third planetary gear  23  and the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 3 . In the embodiment, a gear ratio γ 4  of the fourth forward speed is determined as γ 4 =1.950. In addition, the step ratio between the third forward speed and the fourth forward speed is determined as γ 3 /γ 4 =1.217. 
     The fifth forward speed is established by engaging the clutches C 1  and C 4  and disengaging the remaining clutches C 2 , C 3 , and C 5  and brakes B 1  and B 2 . That is, to establish the fifth forward speed, the third ring gear  23   r  of the third planetary gear  23  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the input shaft  20   i  (the third carrier  23   c  of the third planetary gear  23 ) and the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 4 . In the embodiment, a gear ratio γ 5  of the fifth forward speed is determined as γ 5 =1.470. In addition, the step ratio between the fourth forward speed and the fifth forward speed is determined as γ 4 /γ 5 =1.327. 
     The sixth forward speed is established by engaging the clutches C 1  and C 2  and disengaging the remaining clutches C 3 , C 4 , and C 5  and brakes B 1  and B 2 . That is, to establish the sixth forward speed, the third ring gear  23   r  of the third planetary gear  23  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the input shaft  20   i  and the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . In the embodiment, a gear ratio γ 6  of the sixth forward speed is determined as γ 6 =1.224. In addition, the step ratio between the fifth forward speed and the sixth forward speed is determined as γ 5 /γ 6 =1.201. 
     The seventh forward speed is established by engaging the clutches C 2  and C 4  and disengaging the remaining clutches C 1 , C 3 , and C 5  and brakes B 1  and B 2 . That is, to establish the seventh forward speed, the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the input shaft  20   i  (the third carrier  23   c  of the third planetary gear  23 ) and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 4 . In the embodiment, a gear ratio γ′ 7  of the seventh forward speed is determined as γ 7 =1.000. In addition, the step ratio between the sixth forward speed and the seventh forward speed is determined as γ 6 /γ 7 =1.224. 
     The eighth forward speed is established by engaging the clutches C 2  and C 5  and disengaging the remaining clutches C 1 , C 3 , and C 4  and brakes B 1  and B 2 . That is, to establish the eighth forward speed, the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . In the embodiment, a gear ratio γ 8  of the eighth forward speed is determined as γ 8 =0.870. In addition, the step ratio between the seventh forward speed and the eighth forward speed is determined as γ 7 /γ 8 =1.150. 
     The ninth forward speed is established by engaging the clutches C 2  and C 3  and disengaging the remaining clutches C 1 , C 4 , and C 5  and brakes B 1  and B 2 . That is, to establish the ninth forward speed, the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the third ring gear  23   r  of the third planetary gear  23  and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 3 . In the embodiment, a gear ratio γ 9  of the ninth forward speed is determined as γ 9 =0.817. In addition, the step ratio between the eighth forward speed and the ninth forward speed is determined as γ 8 /γ 9 =1.064. 
     The tenth forward speed is established by engaging the clutch C 2  and the brake B 1  and disengaging the remaining clutches C 1 , C 3 , C 4 , and C 5  and brake B 2 . That is, to establish the tenth forward speed, the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. In the embodiment, a gear ratio γ 10  of the tenth forward speed is determined as γ 10 =0.686. In addition, the step ratio between the ninth forward speed and the tenth forward speed is determined as γ 9 /γ 10 =1.192. 
     The eleventh forward speed is established by engaging the clutches C 4  and C 5  and disengaging the remaining clutches C 1 , C 2 , and C 3  and brakes B 1  and B 2 . That is, to establish the eleventh forward speed, the input shaft  20   i  (the third carrier  23   c  of the third planetary gear  23 ) and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 4 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . In the embodiment, a gear ratio γ 11  of the eleventh forward speed is determined as γ 11 =0.585. In addition, the step ratio between the tenth forward speed and the eleventh forward speed is determined as γ 10 /γ 11 =1.172. Furthermore, the spread (gear ratio width=the gear ratio γ 1  of the first forward speed as the lowest shift speed/the gear ratio γ 11  of the eleventh forward speed as the highest shift speed) of the automatic transmission  20  is determined as γ 1 /γ 11 =8.889. 
     The first reverse speed is established by engaging the clutch C 3  and the brake B 2  and disengaging the remaining clutches C 1 , C 2 , C 4 , and C 5  and brake B 1 . That is, to establish the first reverse speed, the third ring gear  23   r  of the third planetary gear  23  and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 3 . Furthermore, the second driven gear  29  of the second gear train G 2 , that is, the first carrier  21   c  which is coupled to the second driven gear  29  via the second drive gear  28 , is made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. A gear ratio γrev 1  of the first reverse speed is determined as γrev 1 =−4.255. In addition, the step ratio between the first forward speed and the first reverse speed is determined as |γrev 1 /γ 1 |=0.818. 
     The second reverse speed is established by engaging the clutch C 4  and the brake B 2  and disengaging the remaining clutches C 1 , C 2 , C 3 , and C 5  and brake B 1 . That is, to establish the second reverse speed, the input shaft  20   i  (the third carrier  23   c  of the third planetary gear  23 ) and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 4 . Furthermore, the second driven gear  29  of the second gear train G 2 , that is, the first carrier  21   c  which is coupled to the second driven gear  29  via the second drive gear  28 , is made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. A gear ratio γrev 2  of the second reverse speed is determined as γrev 2 =−2.182. In addition, the step ratio between the first forward speed and the second reverse speed is determined as |γrev 2 /γ 1 |=0.420. 
     As discussed above, with the automatic transmission  20 , the first to eleventh forward speeds and the first and second reverse speeds can be established by engaging and disengaging the clutches C 1  to C 5  and the brakes B 1  and B 2 . With the automatic transmission  20 , one of the clutches C 1 , C 2 , and C 4  and the clutch C 5  are engaged to establish the third, eighth, and eleventh forward speeds. When the output gear  20   o  is rotated with the clutch C 5  engaged in this way, the first carrier  21   c  (one of the rotary elements), which is coupled via the second drive gear  28  to the second driven gear  29  which is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , is rotated with respect to the output gear  20   o  at a rotational speed that matches the gear ratio gr 2  of the second gear train G 2 . When the output gear  20   o  is rotated with the clutch C 5  engaged, in addition, the first ring gear  21   r  which is the output element of the Ravigneaux type planetary gear mechanism  25  is rotated with respect to the output gear  20   o  at a rotational speed that matches the gear ratio gr 1  of the first gear train G 1 . Thus, by engaging one of the clutches C 1 , C 2 , and C 4  and the clutch C 5 , a rotational speed difference that matches the gear ratios gr 1  and gr 2  of the first and second gear trains G 1  and G 2  can be caused between the first ring gear  21   r  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25 . Consequently, with the automatic transmission  20 , it is possible to establish shift speeds other than those obtained by selectively engaging two of the clutches C 1  to C 4  and the brakes B 1  and B 2 . 
     That is, when the clutch C 5  is engaged with torque from the input shaft  20   i  transferred to the second sun gear  22   s  (fourth rotary element) of the Ravigneaux type planetary gear mechanism  25  via the third ring gear  23   r  of the third planetary gear  23  through engagement of the clutch C 1 , the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , so that the speed of the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  can be increased compared to the time when the second forward speed is established and the speed of the first ring gear  21   r  can be reduced compared to the time when the fourth forward speed is established as illustrated in  FIG. 2 . Consequently, it is possible to establish the third forward speed with the gear ratio γ 3  which is lower than the gear ratio γ 2  of the second forward speed and higher than the gear ratio γ 4  of the fourth forward speed. 
     When the clutch C 5  is engaged with torque directly transferred from the input shaft  20   i  to the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  through engagement of the clutch C 2 , meanwhile, the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , so that the speed of the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  can be increased compared to the time when the seventh forward speed is established and the speed of the first ring gear  21   r  can be reduced compared to the time when the ninth forward speed is established as illustrated in  FIG. 2 . Consequently, it is possible to establish the eighth forward speed with the gear ratio γ 8  which is lower than the gear ratio γ 7  of the seventh forward speed and higher than the gear ratio γ 9  of the ninth forward speed. 
     When the clutch C 5  is engaged with torque from the input shaft  20   i  transferred to the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  via the third ring gear  23   r  of the third planetary gear  23  through engagement of the clutch C 4 , further, the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , so that the speed of the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  can be increased compared to the time when the tenth forward speed is established as illustrated in  FIG. 2 . Consequently, it is possible to establish the eleventh forward speed with the gear ratio γ 11  which is lower than the gear ratio γ 10  of the tenth forward speed. 
     As discussed above, with the automatic transmission  20  in which torque from the input shaft  20   i  side is selectively (sequentially) transferred to the second sun gear  22   s , the first carrier  21   c , and the first sun gear  21   s , not the first ring gear  21   r  (output element), of the Ravigneaux type planetary gear mechanism  25 , three shift speeds (third, eighth, and eleventh forward speeds) can be added to the speed change device (see JP 2013-204754 A) to which the first and second gear trains G 1  and G 2  and the clutch C 5  have not been added. As a result, with the automatic transmission  20 , the spread can be further increased (in the embodiment, to 8.889) by the addition of the eleventh forward speed as the highest shift speed to improve the fuel efficiency of the vehicle at a high vehicle speed, in particular. By the addition of intermediate shift speeds (third and eighth forward speeds), further, the step ratios can be optimized (an increase in the step ratios can be suppressed) to improve the shifting feeling. Thus, with the automatic transmission  20 , it is possible to improve both the fuel efficiency and the drivability of the vehicle well. 
     In addition, the number of shift speeds can be increased, while suppressing an increase in the size of the entire device or the number of components, by combining the Ravigneaux type planetary gear mechanism  25 , which is a composite planetary gear mechanism with four elements, the first and second gear trains G 1  and G 2 , and the clutch C 5  with each other as in the automatic transmission  20 . With the automatic transmission  20 , further, as illustrated in  FIG. 1 , the brake B 2  can be disposed around the axis (second shaft) of the output gear  20   o . Thus, it is possible to suppress an increase in the physical size around the Ravigneaux type planetary gear mechanism  25  (in an end portion remote from the engine). 
     In the automatic transmission  20 , the gear ratio gr 2  of the second gear train G 2  may be determined as gr 2 =1.00, and the gear ratio gr 1  of the first gear train G 1  may be lower than the gear ratio gr 2  (for example, gr 1 =1.15). In this case, the gear ratios γ 1  to γ 11  of the first to eleventh forward speeds and the gear ratios γrev 1  and γrev 2  of the first and second reverse speeds may have the following values: γ 1 =5.980, γ 2 =3.417, γ 3 =2.730, γ 4 =2.243, γ 5 =1.690, γ 6 =1.407, γ 7 =1.150, γ 8 =1.000, γ 9 =0.940, γ 10 =0.789, γ 11 =0.673, γrev 1 =−4.893, and γrev 2 =−2.509. 
     With the automatic transmission  20 , in addition, it is possible to establish a shift speed with a gear ratio that is lower than the gear ratio γ 6  of the sixth forward speed and higher than the gear ratio γ 7  of the seventh forward speed, as indicated by the dotted line in  FIG. 2 , by engaging the clutch C 3  and the clutch C 5  and the disengaging the remaining clutches C 1 , C 2 , and C 4  and brakes B 1  and B 2 . Thus, with the automatic transmission  20 , as illustrated in  FIG. 4 , the shift speed which is established by engaging the clutch C 3  and the clutch C 5  can be determined as a seventh forward speed, and the seventh to eleventh forward speeds in  FIGS. 2 and 3  can be used as eighth to twelfth forward speeds. Consequently, with the number of shift speeds further increased, it is possible to improve both the fuel efficiency and the drivability of the vehicle significantly well. 
     In the automatic transmission  20 , further, the establishment of the third forward speed in  FIGS. 2 and 3  may be omitted, and the fourth to eleventh forward speeds in  FIGS. 2 and 3  may be used as third to tenth forward speeds (see  FIG. 5 ). In the automatic transmission  20 , in addition, the establishment of the third and eighth forward speeds in  FIGS. 2 and 3  may be omitted, and the fourth to seventh forward speeds in  FIGS. 2 and 3  may be used as third to sixth forward speeds, and the ninth to eleventh forward speeds in  FIGS. 2 and 3  may be used as seventh to ninth forward speeds (see  FIG. 6 ). In such cases as well, the spread can be further increased by the addition of the tenth or ninth forward speed as the highest shift speed to improve the fuel efficiency of the vehicle at a high vehicle speed, in particular. 
       FIG. 7  is a diagram illustrating a schematic configuration of a power transfer device  10 B that includes an automatic transmission  20 B according to a modified aspect of the first embodiment of the present disclosure. Constituent elements of the automatic transmission  20 B that are identical to the elements of the automatic transmission  20  discussed above are given the same numerals to omit redundant descriptions (the same applies hereinafter for the first embodiment). 
     In the automatic transmission  20 B illustrated in  FIG. 7 , the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  which is a first rotary element of the automatic transmission  20 B. In the automatic transmission  20 B, in addition, the brake B 1  makes the first sun gear  21   s  (first securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . In the automatic transmission  20 B, further, the brake B 2  is configured to connect the first carrier  21   c  (second securable element) of the Ravigneaux type planetary gear mechanism  25  to the transmission case  11 , and disposed around the Ravigneaux type planetary gear mechanism  25 . The thus configured automatic transmission  20 B also allows obtaining functions and effects that are similar to those of the automatic transmission  20  discussed above. 
       FIG. 8  is a diagram illustrating a schematic configuration of a power transfer device  10 C that includes an automatic transmission  20 C according to another modified aspect of the first embodiment of the present disclosure. In the automatic transmission  20 C illustrated in the drawing, the first and second planetary gears  21  and  22 , which constitute the Ravigneaux type planetary gear mechanism  25 , and the third planetary gear  23  are disposed in the transmission case  11  so as to be arranged in the order of the third planetary gear  23 , the second planetary gear  22 , and the first planetary gear  21  from the starting device  12  side, that is, the engine side (the right side in  FIG. 8 ). In addition, the third carrier  23   c  of the third planetary gear  23  is connected to (made stationary with respect to) the transmission case  11  via a support member (front support) so as to be non-rotatable. Furthermore, the third sun gear  23   s  of the third planetary gear  23  is always coupled to the input shaft  20   i , and always rotated and stopped together with the input shaft  20   i.    
     In the automatic transmission  20 C, in addition, the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  which is a fourth rotary element of the automatic transmission  20 C. In the example illustrated in  FIG. 8 , the gear ratio gr 2  of the second gear train G 2  is determined to be higher than the gear ratio gr 1  of the first gear train G 1 . In the automatic transmission  20 C, further, the brake B 1  makes the first sun gear  21   s  (first securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the third carrier  23   c  of the third planetary gear  23  and the first sun gear  21   s  to each other. In addition, the brake B 2  is configured to connect the first carrier  21   c  (second securable element) of the Ravigneaux type planetary gear mechanism  25  to the transmission case  11 , and disposed around the Ravigneaux type planetary gear mechanism  25 . Furthermore, the clutch C 4  is configured to connect and disconnect the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  and the input shaft  20   i  to and from each other, and disposed in an end portion of the automatic transmission  20 C that is remote from the engine as with the clutch C 2 . The thus configured automatic transmission  20 C also allows obtaining functions and effects that are similar to those of the automatic transmission  20  discussed above. 
       FIG. 9  is a diagram illustrating a schematic configuration of a power transfer device  10 D that includes an automatic transmission  20 D according to still another modified aspect of the first embodiment of the present disclosure. The automatic transmission  20 D illustrated in the drawing corresponds to the automatic transmission  20  described above, and in the automatic transmission  20 D the Ravigneaux type planetary gear mechanism  25  has been replaced with a composite planetary gear mechanism  25 W constituted by combining the single-pinion type first and second planetary gears  21  and  22  with each other. The first planetary gear  21  of the composite planetary gear mechanism  25 W has a first sun gear  21   s , a first ring gear  21   r , and a first carrier  21   c  that rotatably and revolvably holds a plurality of first pinion gears  21   p  meshed with the first sun gear  21   s  and the first ring gear  21   r . In addition, the second planetary gear  22  has a second sun gear  22   s , a second ring gear  22   r , and a second carrier  22   c  that rotatably and revolvably holds a plurality of second pinion gears  22   p  meshed with the second sun gear  22   s  and the second ring gear  22   r.    
     In the composite planetary gear mechanism  25 W, as illustrated in the drawing, the first ring gear  21   r  of the first planetary gear  21  and the second sun gear  22   s  of the second planetary gear  22  are always coupled to each other. In the example illustrated in  FIG. 9 , the second sun gear  22   s  is shaped integrally (integrated) with the first ring gear  21   r  so as to surround the inner teeth of the first ring gear  21   r . In addition, the first carrier  21   c  of the first planetary gear  21  and the second carrier  22   c  of the second planetary gear  22  are always coupled to each other. Furthermore, the composite planetary gear mechanism  25 W is disposed such that the second planetary gear  22  surrounds the first planetary gear  21 , and such that the first pinion gears  21   p  of the first planetary gear  21  and the second pinion gears  22   p  of the second planetary gear  22  at least partially overlap each other in the axial direction as seen in the radial direction. 
     In addition, the clutch C 1  of the automatic transmission  20 D connects and disconnects the third ring gear  23   r  (sixth rotary element) of the third planetary gear  23  and the first ring gear  21   r  and the second sun gear  22   s  (fourth rotary element), which are always coupled to (integrated with) each other, of the composite planetary gear mechanism  25 W to and from each other. The clutch C 2  connects and disconnects the input shaft  20   i  and the second ring gear  22   r  (second rotary element) of the composite planetary gear mechanism  25 W to and from each other. The clutch C 3  connects and disconnects the third ring gear  23   r  (sixth rotary element) of the third planetary gear  23  and the first sun gear  21   s  (first rotary element) of the composite planetary gear mechanism  25 W to and from each other. The clutch C 4  connects and disconnects the third carrier  23   c  of the third planetary gear  23 , that is, the input shaft  20   i , and the first sun gear  21   s  (first rotary element) of the composite planetary gear mechanism  25 W to and from each other. 
     The brake B 1  makes the first sun gear  21   s  (first securable element) of the composite planetary gear mechanism  25 W stationary with respect to (connects the first sun gear  21   s  to) the transmission case  11  so as to be non-rotatable, and makes the first sun gear  21   s  non-stationary with respect to the transmission case  11 . The brake B 2  makes the second ring gear  22   r  of the composite planetary gear mechanism  25 W stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . The clutch C 5  connects and disconnects the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) to and from each other. 
     Furthermore, the first drive gear (externally toothed gear)  26  of the first gear train G 1  is always coupled coaxially with the first and second carriers  21   c  and  22   c  of the composite planetary gear mechanism  25 W. The first and second carriers  21   c  and  22   c  function as an output element of the composite planetary gear mechanism  25 W. In addition, the second drive gear (externally toothed gear)  28  of the second gear train G 2  is always coupled coaxially with the second ring gear  22   r  (second rotary element) of the composite planetary gear mechanism  25 W. In the example illustrated in  FIG. 9 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . 
       FIG. 10  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to the rotational speed of the input shaft  20   i  (input rotational speed) of the automatic transmission  20 D (note that the rotational speed of the input shaft  20   i , that is, the third carrier  23   c , is defined as a value of 1). As illustrated in the drawing, the four rotary elements which constitute the composite planetary gear mechanism  25 W, that is, the first sun gear  21   s  which serves as the first securable element, the second ring gear  22   r  which serves as the second securable element, the first and second carriers  21   c  and  22   c  which are always coupled to each other and which serve as the output element, and the first ring gear  21   r  and the second sun gear  22   s  which are always coupled to each other, are arranged, on the velocity diagram for the composite planetary gear mechanism  25 W (the velocity diagram on the right side in  FIG. 10 ), in the order of the first sun gear  21   s , the second ring gear  22   r , the first and second carriers  21   c  and  22   c , and the first ring gear  21   r  and the second sun gear  22   s  from the left side of the drawing at intervals that match the gear ratio λ 1  of the first planetary gear  21  and the gear ratio λ 2  of the second planetary gear  22 . Here, according to the order of arrangement on the velocity diagram, the first sun gear  21   s  is defined as a first rotary element of the automatic transmission  20 D, the second ring gear  22   r  is defined as a second rotary element of the automatic transmission  20 D, the first and second carriers  21   c  and  22   c  are defined as a third rotary element of the automatic transmission  20 D, and the first ring gear  21   r  and the second sun gear  22   s  are defined as a fourth rotary element of the automatic transmission  20 D. Thus, the composite planetary gear mechanism  25 W has the first rotary element, the second rotary element, the third rotary element, and the fourth rotary element of the automatic transmission  20 D which are arranged sequentially at intervals that match the gear ratios λ 1  and λ 2  on the velocity diagram. 
     The automatic transmission  20 D configured as discussed above also allows obtaining functions and effects that are similar to those of the automatic transmission  20  described above. By adopting the composite planetary gear mechanism  25 W which is constituted by combining the single-pinion type first and second planetary gears  21  and  22  with each other, it is possible to further improve the assemblability while suppressing an increase in the weight of the automatic transmission  20 D by reducing the number of components. With the composite planetary gear mechanism  25 W illustrated in  FIG. 9 , further, the second planetary gear  22  can be disposed so as to surround the first planetary gear  21 . Thus, it is possible to further shorten the axial length of the automatic transmission  20 D. 
       FIG. 11  is a diagram illustrating a schematic configuration of a power transfer device  10 E that includes an automatic transmission  20 E according to another modified aspect of the first embodiment of the present disclosure. The automatic transmission  20 E illustrated in the drawing corresponds to the automatic transmission  20 B described above, and in the automatic transmission  20 E the Ravigneaux type planetary gear mechanism  25  has been replaced with the composite planetary gear mechanism  25 W. That is, in the automatic transmission  20 E, the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the first sun gear  21   s  of the composite planetary gear mechanism  25 W which is a first rotary element of the automatic transmission  20 E. In the example illustrated in  FIG. 11 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . In the automatic transmission  20 E, in addition, the brake B 1  makes the first sun gear  21   s  (first securable element) of the composite planetary gear mechanism  25 W stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . Furthermore, the brake B 2  is configured to connect the second ring gear  22   r  (second securable element) of the composite planetary gear mechanism  25 W to the transmission case  11 , and disposed around the composite planetary gear mechanism  25 W. The thus configured automatic transmission  20 E also allows obtaining functions and effects that are similar to those of the automatic transmission  20  etc. discussed above. 
       FIG. 12  is a diagram illustrating a schematic configuration of a power transfer device  10 F that includes an automatic transmission  20 F according to another modified aspect of the first embodiment of the present disclosure. The automatic transmission  20 F illustrated in the drawing corresponds to the automatic transmission  20 C described above, and in the automatic transmission  20 F the Ravigneaux type planetary gear mechanism  25  has been replaced with the composite planetary gear mechanism  25 W. That is, in the automatic transmission  20 F, the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the first ring gear  21   r  and the second sun gear  22   s  of the composite planetary gear mechanism  25 W which is a fourth rotary element of the automatic transmission  20 F. In the example illustrated in  FIG. 12 , the gear ratio gr 2  of the second gear train G 2  is determined to be higher than the gear ratio gr 1  of the first gear train G 1 . The thus configured automatic transmission  20 F also allows obtaining functions and effects that are similar to those of the automatic transmission  20  etc. discussed above. 
       FIG. 13  is a diagram illustrating a schematic configuration of a power transfer device  10 G that includes an automatic transmission  20 G according to a second embodiment of the present disclosure. Constituent elements of the automatic transmission  20 G that are identical to the elements of the automatic transmission  20  etc. discussed above are given the same numerals to omit redundant descriptions. 
     The automatic transmission  20 G illustrated in  FIG. 13  corresponds to the automatic transmission  20  discussed above, and in the automatic transmission  20 G the double-pinion type third planetary gear  23  has been replaced with a single-pinion type third planetary gear  230  and the clutch C 4  has been omitted. The third planetary gear  230  has a third sun gear  23   s , a third ring gear  23   r , and a third carrier  23   c  that rotatably and revolvably holds a plurality of third pinion gears  23   p  meshed with the third sun gear  23   s  and the third ring gear  23   r . As illustrated in the drawing, the third sun gear  23   s  of the third planetary gear  230  is connected to (made stationary with respect to) the transmission case  11  via a support member (front support; not illustrated) so as to be non-rotatable. In addition, the third ring gear  23   r  of the third planetary gear  23  is always coupled to the input shaft  20   i , and always rotated and stopped together with the input shaft  20   i . Consequently, the third planetary gear  230  functions as a so-called speed reduction gear, reduces the speed of power transferred to the third ring gear  23   r  serving as an input element, and outputs the resultant power from the third carrier  23   c  serving as an output element. 
     In addition, the clutch C 1  of the automatic transmission  20 G connects and disconnects the third carrier  23   c  of the third planetary gear  23  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The clutch C 2  connects and disconnects the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The clutch C 3  connects and disconnects the third carrier  23   c  of the third planetary gear  23  and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  to and from each other. 
     The brake B 1  makes the first sun gear  21   s  (first securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to (connects the first sun gear  21   s  to) the transmission case  11  so as to be non-rotatable, and makes the first sun gear  21   s  non-stationary with respect to the transmission case  11 . The brake B 2  makes the first carrier  21   c  (second securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to the transmission case  11  so as to be non-rotatable by making the second driven gear  29  of the second gear train G 2  stationary with respect to (connecting the second driven gear  29  to) the transmission case  11  so as to be non-rotatable. The clutch C 5  connects and disconnects the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) to and from each other. 
       FIG. 14  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to the rotational speed of the input shaft  20   i  (input rotational speed) of the automatic transmission  20 G (note that the rotational speed of the input shaft  20   i , that is, the third ring gear  23   r , is defined as a value of 1). In addition,  FIG. 15  is an operation table illustrating the relationship between each shift speed of the automatic transmission  20 G and the respective operating states of the clutches C 1  to C 3  and C 5  and the brakes B 1  and B 2 . 
     In the automatic transmission  20 G, according to the order of arrangement on the velocity diagram illustrated in  FIG. 14 , the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  is defined as a first rotary element of the automatic transmission  20 G, the first carrier  21   c  is defined as a second rotary element of the automatic transmission  20 G; the first ring gear  21   r  is defined as a third rotary element of the automatic transmission  20 G and the second sun gear  22   s  is defined as a fourth rotary element of the automatic transmission  20 G In addition, the three rotary elements which constitute the single-pinion type third planetary gear  230 , that is, the third sun gear (stationary element)  23   s , the third ring gear  23   r  (output element), and the third carrier  23   c  (input element), are arranged, on the velocity diagram for the third planetary gear  230  (the velocity diagram on the left side in  FIG. 14 ), in the order of the third sun gear  23   s , the third carrier  23   c , and the third ring gear  23   r  from the left side of the drawing at intervals that match the gear ratio. Here, according to the order of arrangement on the velocity diagram, the third sun gear  23   s  is defined as a fifth rotary element of the automatic transmission  20 G, the third carrier  23   c  is defined as a sixth rotary element of the automatic transmission  20 G, and the third ring gear  23   r  is defined as a seventh rotary element of the automatic transmission  20 G. 
     In the automatic transmission  20 G the clutches C 1  to C 3  and C 5  and the brakes B 1  and B 2  are engaged and disengaged as illustrated in  FIG. 15  to change the relationship of connection of the first to seventh rotary elements discussed above, which allows establishing nine power transfer paths in the forward rotational direction and one power transfer path in the reverse rotational direction from the input shaft  20   i  to the output gear  20   o , that is, first to ninth forward speeds and a reverse speed. 
     Specifically, the first forward speed of the automatic transmission  20 G is established by engaging the clutch C 1  and the brake B 2  and disengaging the remaining clutches C 2 , C 3 , and C 5  and brake B 1 . That is, to establish the first forward speed, the third carrier  23   c  (sixth rotary element) of the third planetary gear  230  and the second sun gear  22   s  (fourth rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. The second forward speed is established by engaging the clutch C 1  and the brake B 1  and disengaging the remaining clutches C 2 , C 3 , and C 5  and brake B 2 . That is, to establish the second forward speed, the third carrier  23   c  of the third planetary gear  230  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. 
     The third forward speed is established by engaging the clutches C 1  and C 5  and disengaging the remaining clutches C 2  and C 3  and brakes B 1  and B 2 . That is, to establish the third forward speed, the third carrier  23   c  of the third planetary gear  230  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The fourth forward speed is established by engaging the clutches C 1  and C 3  and disengaging the remaining clutches C 2  and C 5  and brakes B 1  and B 2 . That is, to establish the fourth forward speed, the third carrier  23   c  of the third planetary gear  230  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the third carrier  23   c  (sixth rotary element) of the third planetary gear  230  and the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 3 . 
     The fifth forward speed is established by engaging the clutches C 3  and C 5  and disengaging the remaining clutches C 1  and C 2  and brakes B 1  and B 2 . That is, to establish the fifth forward speed, the third carrier  23   c  of the third planetary gear  230  and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 3 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The sixth forward speed is established by engaging the clutches C 1  and C 2  and disengaging the remaining clutches C 3  and C 5  and brakes B 1  and B 2 . That is, to establish the sixth forward speed, the third carrier  23   c  of the third planetary gear  230  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the input shaft  20   i  and the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . 
     The seventh forward speed is established by engaging the clutches C 2  and C 5  and disengaging the remaining clutches C 1  and C 3  and brakes B 1  and B 2 . That is, to establish the seventh forward speed, the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The eighth forward speed is established by engaging the clutches C 2  and C 3  and disengaging the remaining clutches C 1  and C 5  and brakes B 1  and B 2 . That is, to establish the eighth forward speed, the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the third carrier  23   c  of the third planetary gear  230  and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 3 . 
     The ninth forward speed is established by engaging the clutch C 2  and the brake B 1  and disengaging the remaining clutches C 1 , C 3 , and C 5  and brake B 2 . That is, to establish the ninth forward speed, the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. The reverse speed is established by engaging the clutch C 3  and the brake B 2  and disengaging the remaining clutches C 1 , C 2 , and C 5  and brake B 1 . That is, to establish the reverse speed, the third carrier  23   c  of the third planetary gear  230  and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 3 . Furthermore, the second driven gear  29  of the second gear train G 2 , that is, the first carrier  21   c  which is coupled to the second driven gear  29  via the second drive gear  28 , is made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. 
     As discussed above, with the automatic transmission  20 G the first to ninth forward speeds and the reverse speed can be established by engaging and disengaging the clutches C 1  to C 3  and C 5  and the brakes B 1  and B 2 . With the automatic transmission  20 G one of the clutches C 1  to C 3  and the clutch C 5  are engaged to establish the third, fifth, and seventh forward speeds. When the output gear  20   o  is rotated with the clutch C 5  engaged in this way, the first carrier  21   c  (one of the rotary elements), which is coupled via the second drive gear  28  to the second driven gear  29  which is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , is rotated with respect to the output gear  20   o  at a rotational speed that matches the gear ratio gr 2  of the second gear train G 2  in the same direction as the output gear  20   o  and the first drive gear  26 . When the output gear  20   o  is rotated with the clutch C 5  engaged, in addition, the first ring gear  21   r  which is the output element of the Ravigneaux type planetary gear mechanism  25  is rotated with respect to the output gear  20   o  at a rotational speed that matches the gear ratio gr 1  of the first gear train G 1 . Thus, by engaging one of the clutches C 1  to C 3  and the clutch C 5 , a rotational speed difference that matches the gear ratios gr 1  and gr 2  of the first and second gear trains G 1  and G 2  can be caused between the first ring gear  21   r  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25 . Consequently, with the automatic transmission  20 G it is possible to establish shift speeds other than those obtained by selectively engaging two of the clutches C 1  to C 3  and the brakes B 1  and B 2 . 
     That is, when the clutch C 5  is engaged with torque from the input shaft  20   i  transferred to the second sun gear  22   s  (fourth rotary element) of the Ravigneaux type planetary gear mechanism  25  via the third carrier  23   c  of the third planetary gear  23  through engagement of the clutch C 1 , the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , so that the speed of the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  can be increased compared to the time when the second forward speed is established and the speed of the first ring gear  21   r  can be reduced compared to the time when the fourth forward speed is established as illustrated in  FIG. 14 . Consequently, it is possible to establish the third forward speed with the gear ratio γ 3  which is lower than the gear ratio γ 2  of the second forward speed and higher than the gear ratio γ 4  of the fourth forward speed. 
     When the clutch C 5  is engaged with torque from the input shaft  20   i  transferred to the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  via the third carrier  23   c  of the third planetary gear  230  through engagement of the clutch C 3 , meanwhile, the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , so that the speed of the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  can be increased compared to the time when the fourth forward speed is established as illustrated in  FIG. 14 . Consequently, it is possible to establish the fifth forward speed with the gear ratio γ 5  which is lower than the gear ratio γ 4  of the fourth forward speed and higher than the gear ratio γ 6  of the sixth forward speed. 
     When the clutch C 5  is engaged with torque directly transferred from the input shaft  20   i  to the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  through engagement of the clutch C 2 , further, the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , so that the speed of the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  can be reduced compared to the time when the eighth forward speed is established as illustrated in  FIG. 14 . Consequently, it is possible to establish the seventh forward speed with the gear ratio γ 7  which is lower than the gear ratio γ 6  of the sixth forward speed and higher than the gear ratio γ 8  of the eighth forward speed. 
     As discussed above, with the automatic transmission  20 G in which torque from the input shaft  20   i  side is selectively (sequentially) transferred to the second sun gear  22   s , the first sun gear  21   s , and the first carrier  21   c , not the first ring gear  21   r  (output element), of the Ravigneaux type planetary gear mechanism  25 , three shift speeds (third, fifth, and seventh forward speeds) can be added to the speed change device (see JP 2010-038168 A) to which the first and second gear trains G 1  and G 2  and the clutch C 5  have not been added. As a result, with the automatic transmission  20 G, by the addition of intermediate shift speeds (third, fifth, and seventh forward speeds), it is possible to optimize the step ratios (suppress an increase in the step ratios), which improves the acceleration performance at each shift speed and the shifting feeling. Thus, with the automatic transmission  20 G, it is possible to improve the drivability well along with improving the fuel efficiency of the vehicle by increasing the number of shift speeds. 
     With the automatic transmission  20 G, in addition, it is possible to increase the number of shift speeds, while suppressing an increase in the size of the entire device or the number of components, by combining the Ravigneaux type planetary gear mechanism  25 , which is a composite planetary gear mechanism with four elements, the first and second gear trains G 1  and G 2 , and the clutch C 5  with each other. With the automatic transmission  20 G, further, as illustrated in  FIG. 13 , the brake B 2  can be disposed around the axis (second shaft) of the output gear  20   o . Thus, it is possible to suppress an increase in the physical size around the Ravigneaux type planetary gear mechanism  25  (in an end portion remote from the engine). 
       FIG. 16  is a diagram illustrating a schematic configuration of a power transfer device  10 H that includes an automatic transmission  20 H according to a modified aspect of the second embodiment of the present disclosure. The automatic transmission  20 H illustrated in the drawing corresponds to the automatic transmission  20 G discussed above, and in the automatic transmission  20 H the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the first sun gear  21   s  (first rotary element) in place of the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25 . In the automatic transmission  20 H, in addition, the brake B 1  makes the first sun gear  21   s  (first securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . In the automatic transmission  20 H, further, the brake B 2  is configured to connect the first carrier  21   c  (second securable element) of the Ravigneaux type planetary gear mechanism  25  to the transmission case  11 , and disposed around the Ravigneaux type planetary gear mechanism  25 . The thus configured automatic transmission  20 H also allows obtaining functions and effects that are similar to those of the automatic transmission  20 G discussed above. 
       FIG. 17  is a diagram illustrating a schematic configuration of a power transfer device  10 I that includes an automatic transmission  20 I according to another modified aspect of the second embodiment of the present disclosure. The automatic transmission  20 I illustrated in the drawing corresponds to the automatic transmission  20 C discussed above (see  FIG. 8 ), and in the automatic transmission  20 I the clutch C 4  has been omitted. The thus configured automatic transmission  20 I also allows obtaining functions and effects that are similar to those of the automatic transmission  20 G discussed above. 
       FIG. 18  is a diagram illustrating a schematic configuration of a power transfer device  10 J that includes an automatic transmission  20 J according to still another modified aspect of the second embodiment of the present disclosure. The automatic transmission  20 J illustrated in the drawing corresponds to the automatic transmission  20 G described above, and in the automatic transmission  20 J the Ravigneaux type planetary gear mechanism  25  has been replaced with a so-called CR-CR type composite planetary gear mechanism  250  constituted by combining the single-pinion type first and second planetary gears  21  and  22  with each other. In the composite planetary gear mechanism  250 , as illustrated in the drawing, the first carrier  21   c  of the first planetary gear  21  and the second ring gear  22   r  of the second planetary gear  22  are always coupled to each other, and the first ring gear  21   r  of the first planetary gear  21  and the second carrier  22   c  of the second planetary gear  22  are always coupled to each other. 
     Furthermore, the first drive gear (externally toothed gear)  26  of the first gear train G 1  is always coupled coaxially with the first carrier  21   c  and the second ring gear  22   r  of the composite planetary gear mechanism  250 . The first carrier  21   c  and the second ring gear  22   r  function as an output element of the composite planetary gear mechanism  250 . In addition, the second drive gear (externally toothed gear)  28  of the second gear train G 2  is always coupled coaxially with the first ring gear  21   r  and the second carrier  22   c  (second rotary element) of the composite planetary gear mechanism  250 . In the example illustrated in  FIG. 18 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . 
     In addition, the clutch C 1  of the automatic transmission  20 J connects and disconnects the third carrier  23   c  of the third planetary gear  230  and the first sun gear  21   s  of the composite planetary gear mechanism  250  to and from each other. The clutch C 2  connects and disconnects the third ring gear  23   r  of the third planetary gear  230 , that is, the input shaft  20   i , and the first ring gear  21   r  and the second carrier  22   c  of the composite planetary gear mechanism  250  to and from each other. The clutch C 3  connects and disconnects the third ring gear  23   r  of the third planetary gear  230 , that is, the input shaft  20   i , and the second sun gear  22   s  of the composite planetary gear mechanism  250  to and from each other. The brake B 1  makes the second sun gear  22   s  (first securable element) of the composite planetary gear mechanism  250  stationary with respect to (connects the second sun gear  22   s  to) the transmission case  11  so as to be non-rotatable, and makes the second sun gear  22   s  non-stationary with respect to the transmission case  11 . The brake B 2  makes the first ring gear  21   r  and the second carrier  22   c  (second securable element) of the composite planetary gear mechanism  250  stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . The clutch C 5  connects and disconnects the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) to and from each other. 
       FIG. 19  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to the rotational speed of the input shaft  20   i  (input rotational speed) of the automatic transmission  20 J (note that the rotational speed of the input shaft  20   i , that is, the third ring gear  23   r , is defined as a value of 1). As illustrated in the drawing, the four rotary elements which constitute the composite planetary gear mechanism  250 , that is, the second sun gear  22   s  which serves as the first securable element, the first ring gear  21   r  and the second carrier  22   c  which are always coupled to each other and which serve as the second securable element, the first carrier  21   c  and the second ring gear  22   r  which are always coupled to each other and which serve as the output element, and the first sun gear  21   s , are arranged, on the velocity diagram for the composite planetary gear mechanism  250  (the velocity diagram on the right side in  FIG. 19 ), in the order of the second sun gear  22   s , the first ring gear  21   r  and the second carrier  22   c , the first carrier  21   c  and the second ring gear  22   r , and the first sun gear  21   s  from the left side of the drawing at intervals that match the gear ratio λ 1  of the first planetary gear  21  and the gear ratio λ 2  of the second planetary gear  22 . Here, according to the order of arrangement on the velocity diagram, the second sun gear  22   s  is defined as a first rotary element of the automatic transmission  20 J, the first ring gear  21   r  and the second carrier  22   c  are defined as a second rotary element of the automatic transmission  20 J, the first carrier  21   c  and the second ring gear  22   r  are defined as a third rotary element of the automatic transmission  20 J, and the first sun gear  21   s  is defined as a fourth rotary element of the automatic transmission  20 J. Thus, the composite planetary gear mechanism  250  has the first rotary element, the second rotary element, the third rotary element, and the fourth rotary element of the automatic transmission  20 J which are arranged sequentially at intervals that match the gear ratios λ 1  and λ 2  on the velocity diagram. 
     In the automatic transmission  20 J, the clutches C 1  to C 3  and C 5  and the brakes B 1  and B 2  are engaged and disengaged as illustrated in  FIG. 20  to change the relationship of connection of the first to seventh rotary elements discussed above, which allows establishing nine power transfer paths in the forward rotational direction and one power transfer path in the reverse rotational direction from the input shaft  20   i  to the output gear  20   o , that is, first to ninth forward speeds and a reverse speed. 
     Specifically, the first forward speed of the automatic transmission  20 J is established by engaging the clutch C 1  and the brake B 2  and disengaging the remaining clutches C 2 , C 3 , and C 5  and brake B 1 . That is, to establish the first forward speed, the third carrier  23   c  (sixth rotary element) of the third planetary gear  230  and the first sun gear  21   s  (fourth rotary element) of the composite planetary gear mechanism  250  are connected to each other by the clutch C 1 . Furthermore, the first ring gear  21   r  and the second carrier  22   c  (second rotary element) of the composite planetary gear mechanism  250  are made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. The second forward speed is established by engaging the clutch C 1  and the brake B 1  and disengaging the remaining clutches C 2 , C 3 , and C 5  and brake B 2 . That is, to establish the second forward speed, the third carrier  23   c  of the third planetary gear  230  and the first sun gear  21   s  of the composite planetary gear mechanism  250  are connected to each other by the clutch C 1 . Furthermore, the second sun gear  22   s  (first rotary element) of the composite planetary gear mechanism  250  is made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. 
     The third forward speed is established by engaging the clutches C 1  and C 5  and disengaging the remaining clutches C 2  and C 3  and brakes B 1  and B 2 . That is, to establish the third forward speed, the third carrier  23   c  of the third planetary gear  230  and the first sun gear  21   s  of the composite planetary gear mechanism  250  are connected to each other by the clutch C 1 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The fourth forward speed is established by engaging the clutches C 1  and C 3  and disengaging the remaining clutches C 2  and C 5  and brakes B 1  and B 2 . That is, to establish the fourth forward speed, the third carrier  23   c  of the third planetary gear  230  and the first sun gear  21   s  of the composite planetary gear mechanism  250  are connected to each other by the clutch C 1 . Furthermore, the input shaft  20   i  (the third ring gear  23   r  of the third planetary gear  230 ) and the second sun gear  22   s  (first rotary element) of the composite planetary gear mechanism  250  are connected to each other by the clutch C 3 . 
     The fifth forward speed is established by engaging the clutches C 1  and C 2  and disengaging the remaining clutches C 3  and C 5  and brakes B 1  and B 2 . That is, to establish the fifth forward speed, the third carrier  23   c  of the third planetary gear  230  and the first sun gear  21   s  of the composite planetary gear mechanism  250  are connected to each other by the clutch C 1 . Furthermore, the input shaft  20   i  (third ring gear  23   r ) and the first ring gear  21   r  and the second carrier  22   c  (second rotary element) of the composite planetary gear mechanism  250  are connected to each other by the clutch C 2 . The sixth forward speed is established by engaging the clutches C 2  and C 3  and disengaging the remaining clutches C 1  and C 5  and brakes B 1  and B 2 . That is, to establish the sixth forward speed, the input shaft  20   i  (third ring gear  23   r ) and the first ring gear  21   r  and the second carrier  22   c  of the composite planetary gear mechanism  250  are connected to each other by the clutch C 2 . Furthermore, the input shaft  20   i  (third ring gear  23   r )) and the second sun gear  22   s  (first rotary element) of the composite planetary gear mechanism  250  are connected to each other by the clutch C 3 . 
     The seventh forward speed is established by engaging the clutches C 2  and C 5  and disengaging the remaining clutches C 1  and C 3  and brakes B 1  and B 2 . That is, to establish the seventh forward speed, the input shaft  20   i  (third ring gear  23   r ) and the first ring gear  21   r  and the second carrier  22   c  of the composite planetary gear mechanism  250  are connected to each other by the clutch C 2 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The eighth forward speed is established by engaging the clutch C 2  and the brake B 1  and disengaging the remaining clutches C 1 , C 3 , and C 5  and brake B 2 . That is, to establish the eighth forward speed, the input shaft  20   i  (third ring gear  23   r ) and the first ring gear  21   r  and the second carrier  22   c  of the composite planetary gear mechanism  250  are connected to each other by the clutch C 2 . Furthermore, the second sun gear  22   s  of the composite planetary gear mechanism  250  is made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. 
     The ninth forward speed is established by engaging the clutches C 3  and C 5  and disengaging the remaining clutches C 1  and C 2  and brakes B 1  and B 2 . That is, to establish the ninth forward speed, the input shaft  20   i  (third ring gear  23   r ) and the second sun gear  22   s  of the composite planetary gear mechanism  250  are connected to each other by the clutch C 3 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The reverse speed is established by engaging the clutch C 3  and the brake B 2  and disengaging the remaining clutches C 1 , C 2 , and C 5  and brake B 1 . That is, to establish the reverse speed, the input shaft  20   i  (third ring gear  23   r ) and the second sun gear  22   s  of the composite planetary gear mechanism  250  are connected to each other by the clutch C 3 . Furthermore, the first ring gear  21   r  and the second carrier  22   c  of the composite planetary gear mechanism  250  are made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. 
     As discussed above, also with the automatic transmission  20 J, the first to ninth forward speeds and the reverse speed can be established by engaging and disengaging the clutches C 1  to C 3  and C 5  and the brakes B 1  and B 2 . That is, also with the automatic transmission  20 J, three shift speeds (third, seventh, and ninth forward speeds) can be added to the speed change device (see JP 2010-038168 A) to which the first and second gear trains G 1  and G 2  and the clutch C 5  have not been added. As a result, with the automatic transmission  20 J, the spread can be further increased by the addition of the ninth forward speed as the highest shift speed to improve the fuel efficiency of the vehicle at a high vehicle speed and the acceleration performance at each shift speed, in particular. By the addition of intermediate shift speeds (third and seventh forward speeds), further, the step ratios can be optimized (an increase in the step ratios can be suppressed) to improve the shifting feeling. Thus, also with the automatic transmission  20 J, it is possible to improve both the fuel efficiency and the drivability of the vehicle well. In addition, by adopting the CR-CR type composite planetary gear mechanism  250  which is constituted by combining the single-pinion type first and second planetary gears  21  and  22  with each other, it is possible to further improve the power transfer efficiency of the automatic transmission  20 J by reducing a meshing loss between the rotary elements of the composite planetary gear mechanism  250 , and to improve the assemblability while suppressing an increase in the weight of the entire device by reducing the number of components. 
       FIG. 21  is a diagram illustrating a schematic configuration of a power transfer device  10 K that includes an automatic transmission  20 K according to another modified aspect of the second embodiment of the present disclosure. In the automatic transmission  20 K illustrated in the drawing, the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the first sun gear  21   s  of the composite planetary gear mechanism  250  which is a fourth rotary element of the automatic transmission  20 K. In the example illustrated in  FIG. 21 , the gear ratio gr 2  of the second gear train G 2  is determined to be higher than the gear ratio gr 1  of the first gear train G 1 . In the automatic transmission  20 K, in addition, the brake B 2  is configured to connect the first ring gear  21   r  and the second carrier  22   c  (second securable element) of the composite planetary gear mechanism  250  to the transmission case  11 , and disposed around the composite planetary gear mechanism  250 . The thus configured automatic transmission  20 K also allows obtaining functions and effects that are similar to those of the automatic transmission  20 J discussed above. 
       FIG. 22  is a diagram illustrating a schematic configuration of a power transfer device  10 L that includes an automatic transmission  20 L according to still another modified aspect of the second embodiment of the present disclosure. In the automatic transmission  20 L illustrated in the drawing, the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the second sun gear  22   s  of the composite planetary gear mechanism  250  which is a first rotary element of the automatic transmission  20 L. In the example illustrated in  FIG. 22 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . In the automatic transmission  20 L, in addition, the brake B 1  makes the second sun gear  22   s  (first securable element) of the composite planetary gear mechanism  250  stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . Furthermore, the brake B 2  is configured to connect the first ring gear  21   r  and the second carrier  22   c  (second securable element) of the composite planetary gear mechanism  250  to the transmission case  11 , and disposed around the composite planetary gear mechanism  250 . The thus configured automatic transmission  20 L also allows obtaining functions and effects that are similar to those of the automatic transmission  20 J discussed above. 
       FIG. 23  is a diagram illustrating a schematic configuration of a power transfer device  10 M that includes an automatic transmission  20 M according to another modified aspect of the second embodiment of the present disclosure. The automatic transmission  20 M illustrated in the drawing includes a Ravigneaux type planetary gear mechanism  25  which serves as a composite planetary gear mechanism constituted by combining a single-pinion type first planetary gear  21  and a double-pinion type second planetary gear  22  with each other, and a single-pinion type third planetary gear  230 . In the example illustrated in  FIG. 23 , the first and second planetary gears  21  and  22 , which constitute the Ravigneaux type planetary gear mechanism  25 , and the third planetary gear  23  are disposed in the transmission case  11  so as to be arranged in the order of the third planetary gear  23 , the second planetary gear  22 , and the first planetary gear  21  from the starting device  12  side, that is, the engine side (the right side in  FIG. 1 ). 
     As illustrated in the drawing, the first drive gear (externally toothed gear)  26  of the first gear train G 1  is always coupled coaxially with the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25 . The first carrier  21   c  functions as an output element of the Ravigneaux type planetary gear mechanism  25 . Furthermore, the second drive gear (externally toothed gear)  28  of the second gear train G 2  is always coupled coaxially with the first ring gear  21   r  (second rotary element) of the Ravigneaux type planetary gear mechanism  25 . In the example illustrated in  FIG. 23 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . In addition, the third sun gear  23   s  of the third planetary gear  230  is always coupled to the input shaft  20   i , and always rotated and stopped together with the input shaft  20   i.    
     Furthermore, the automatic transmission  20 M includes a clutch C 1  (third engagement element), a clutch C 2  (fourth engagement element), a brake B 1  (first engagement element), a brake B 2  (second engagement element), a brake B 3  (fifth engagement element), and a clutch C 5  (output-side engagement element), all of which are used to change a power transfer path from the input shaft  20   i  to the output gear  20   o.    
     The clutch C 1  connects and disconnects the input shaft  20   i  (third sun gear  23   s ) and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The clutch C 2  connects and disconnects the input shaft  20   i  (third sun gear  23   s ) and the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The brake B 1  makes the third carrier  23   c  of the third planetary gear  230  and the second sun gear  22   s  (first securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to (connects the third carrier  23   c  and the second sun gear  22   s  to) the transmission case  11  so as to be non-rotatable, and makes the third carrier  23   c  and the second sun gear  22   s  non-stationary with respect to the transmission case  11 . The brake B 2  makes the first ring gear  21   r  (second securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to the transmission case  11  by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . The brake B 3  makes the third ring gear  23   r  of the third planetary gear  230  stationary with respect to (connects the third ring gear  23   r  to) the transmission case  11  so as to be non-rotatable, and makes the third ring gear  23   r  non-stationary with respect to the transmission case  11 . The clutch C 5  connects and disconnects the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) to and from each other. 
     In the automatic transmission  20 M, according to the order of arrangement on the velocity diagram illustrated in  FIG. 24 , the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  is defined as a first rotary element of the automatic transmission  20 M, the first ring gear  21   r  is defined as a second rotary element of the automatic transmission  20 M, the first carrier  21   c  is defined as a third rotary element of the automatic transmission  20 M, and the first sun gear  21   s  is defined as a fourth rotary element of the automatic transmission  20 M. In addition, the third sun gear  23   s  is defined as a fifth rotary element of the automatic transmission  20 M, the third carrier  23   c  is defined as a sixth rotary element of the automatic transmission  20 M, and the third ring gear  23   r  is defined as a seventh rotary element of the automatic transmission  20 M. 
     In the automatic transmission  20 M, the clutches C 1 , C 2 , and C 5  and the brakes B 1 , B 2 , and B 3  are engaged and disengaged as illustrated in  FIG. 25  to change the relationship of connection of the first to seventh rotary elements discussed above, which allows establishing nine power transfer paths in the forward rotational direction and one power transfer path in the reverse rotational direction from the input shaft  20   i  to the output gear  20   o , that is, first to ninth forward speeds and a reverse speed. 
     Specifically, the first forward speed of the automatic transmission  20 M is established by engaging the clutch C 1  and the brake B 2  and disengaging the remaining clutches C 2 , and C 5  and brakes B 1  and B 3 . That is, to establish the first forward speed, the input shaft  20   i  (third sun gear  23   s ) and the first sun gear  21   s  (fourth rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the first ring gear  21   r  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. The second forward speed is established by engaging the clutch C 1  and the brake B 1  and disengaging the remaining clutches C 2 , and C 5  and brakes B 2  and B 3 . That is, to establish the second forward speed, the input shaft  20   i  (third sun gear  23   s ) and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the third carrier  23   c  of the third planetary gear  230  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  (first and sixth rotary elements) are made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. 
     The third forward speed is established by engaging the clutch C 5  and the brake B 3  and disengaging the remaining clutches C 1  and C 2  and brakes B 1  and B 2 . That is, to establish the third forward speed, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . Furthermore, the third ring gear  23   r  (seventh rotary element) of the third planetary gear  230  is made stationary with respect to the transmission case  11  by the brake B 3  so as to be non-rotatable. The fourth forward speed is established by engaging the clutch C 1  and the brake B 3  and disengaging the remaining clutches C 2  and C 5  and brakes B 1  and B 2 . That is, to establish the fourth forward speed, the input shaft  20   i  (third sun gear  23   s ) and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the third ring gear  23   r  of the third planetary gear  230  is made stationary with respect to the transmission case  11  by the brake B 3  so as to be non-rotatable. 
     The fifth forward speed is established by engaging the clutches C 1  and C 5  and disengaging the remaining clutch C 2  and brakes B 1 , B 2 , and B 3 . That is, to establish the fifth forward speed, the input shaft  20   i  (third sun gear  23   s ) and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The sixth forward speed is established by engaging the clutches C 1  and C 2  and disengaging the remaining clutch C 5  and brakes B 1 , B 2 , and B 3 . That is, to establish the sixth forward speed, the input shaft  20   i  (third sun gear  23   s ) and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the input shaft  20   i  (third sun gear  23   s ) and the first ring gear  21   r  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . 
     The seventh forward speed is established by engaging the clutches C 2  and C 5  and disengaging the remaining clutch C 1  and brakes B 1 , B 2 , and B 3 . The input shaft  20   i  (third sun gear  23   s ) and the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The eighth forward speed is established by engaging the clutch C 2  and the brake B 3  and disengaging the remaining clutches C 1  and C 5  and brakes B 1  and B 2 . That is, to establish the eighth forward speed, the input shaft  20   i  (third sun gear  23   s ) and the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the third ring gear  23   r  of the third planetary gear  230  is made stationary with respect to the transmission case  11  by the brake B 3  so as to be non-rotatable. 
     The ninth forward speed is established by engaging the clutch C 2  and the brake B 1  and disengaging the remaining clutches C 1  and C 5  and brakes B 2  and B 3 . That is, to establish the ninth forward speed, the input shaft  20   i  (third sun gear  23   s ) and the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the third carrier  23   c  of the third planetary gear  230  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. The reverse speed is established by engaging the brakes B 2  and B 3  and disengaging the remaining clutches C 1 , C 2 , and C 5  and brake B 1 . That is, to establish the reverse speed, the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. Furthermore, the third ring gear  23   r  of the third planetary gear  230  is made stationary with respect to the transmission case  11  by the brake B 3  so as to be non-rotatable. 
     As discussed above, with the automatic transmission  20 M, the first to ninth forward speeds and the reverse speed can be established by engaging and disengaging the clutches C 1 , C 2 , and C 5  and the brakes B 1 , B 2 , and B 3 . With the automatic transmission  20 M, one of the clutch C 1 , the clutch C 2 , and the brake B 3  and the clutch C 5  are engaged to establish the third, fifth, and seventh forward speeds. When the output gear  20   o  is rotated with the clutch C 5  engaged in this way, the first ring gear  21   r  (one of the rotary elements), which is coupled via the second drive gear  28  to the second driven gear  29  which is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , is rotated with respect to the output gear  20   o  at a rotational speed that matches the gear ratio gr 2  of the second gear train G 2 . When the output gear  20   o  is rotated with the clutch C 5  engaged, in addition, the first carrier  21   c  which is the output element of the Ravigneaux type planetary gear mechanism  25  is rotated with respect to the output gear  20   o  at a rotational speed that matches the gear ratio gr 1  of the first gear train G 1 . Thus, by engaging one of the clutch C 1 , the clutch C 2 , and the brake B 3  and the clutch C 5 , a rotational speed difference that matches the gear ratios gr 1  and gr 2  of the first and second gear trains G 1  and G 2  can be caused between the first ring gear  21   r  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25 . Consequently, also with the automatic transmission  20 M, it is possible to establish shift speeds other than those obtained by selectively engaging two of the clutches C 1  and C 2  and the brakes B 1 , B 2 , and B 3 . 
     That is, when the clutch C 5  is engaged with torque from the input shaft  20   i  transferred to the second sun gear  22   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  via the third carrier  23   c  (sixth rotary element) of the third planetary gear  230  through engagement of the brake B 3 , the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27  so that the speed of the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  can be reduced compared to the time when the fourth forward speed is established as illustrated in  FIG. 24 . Consequently, it is possible to establish the third forward speed with the gear ratio γ 3  which is lower than the gear ratio γ 2  of the second forward speed and higher than the gear ratio γ 4  of the fourth forward speed. 
     When the clutch C 5  is engaged with torque from the input shaft  20   i  directly transferred from the input shaft  20   i  to the first sun gear  21   s  (fourth rotary element) of the Ravigneaux type planetary gear mechanism  25  through engagement of the clutch C 1 , meanwhile, the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27  so that the speed of the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  can be increased compared to the time when the fourth forward speed is established and the speed of the first carrier  21   c  can be reduced compared to the time when the sixth forward speed is established as illustrated in  FIG. 24 . Consequently, it is possible to establish the fifth forward speed with the gear ratio γ 5  which is lower than the gear ratio γ 4  of the fourth forward speed and higher than the gear ratio γ 6  of the sixth forward speed. 
     When the clutch C 5  is engaged with torque directly transferred from the input shaft  20   i  to the first ring gear  21   r  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  through engagement of the clutch C 2 , further, the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27  so that the speed of the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  can be reduced compared to the time when the eighth forward speed is established as illustrated in  FIG. 24 . Consequently, it is possible to establish the seventh forward speed with the gear ratio γ 7  which is lower than the gear ratio γ 6  of the sixth forward speed and higher than the gear ratio γ 8  of the eighth forward speed. 
     As discussed above, with the automatic transmission  20 M in which torque from the input shaft  20   i  side is selectively (sequentially) transferred to the second sun gear  22   s , the first sun gear  21   s , and the first ring gear  21   r , not the first carrier  21   c  (output element), of the Ravigneaux type planetary gear mechanism  25 , three shift speeds (third, fifth, and seventh forward speeds) can be added to the speed change device to which the first and second gear trains G 1  and G 2  and the clutch C 5  have not been added. As a result, with the automatic transmission  20 M, by the addition of intermediate shift speeds (third, fifth, and seventh forward speeds), it is possible to optimize the step ratios (suppress an increase in the step ratios), which improves the acceleration performance at each shift speed and the shifting feeling. Thus, also with the automatic transmission  20 M, it is possible to improve the drivability well along with improving the fuel efficiency of the vehicle by increasing the number of shift speeds. 
     The automatic transmission  20 M also allows increasing the number of shift speeds, while suppressing an increase in the size of the entire device or the number of components, by combining the Ravigneaux type planetary gear mechanism  25 , which is a composite planetary gear mechanism with four elements, the first and second gear trains G 1  and G 2 , and the clutch C 5  with each other. Also with the automatic transmission  20 M, further, as illustrated in  FIG. 23 , the brake B 2  can be disposed around the axis (second shaft) of the output gear  20   o . Thus, it is possible to suppress an increase in the physical size around the Ravigneaux type planetary gear mechanism  25  (in an end portion remote from the engine). 
       FIG. 26  is a diagram illustrating a schematic configuration of a power transfer device  10 N that includes an automatic transmission  20 N according to still another modified aspect of the second embodiment of the present disclosure. The automatic transmission  20 N illustrated in the drawing corresponds to the automatic transmission  20 M discussed above, and in the automatic transmission  20 N the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the second sun gear  22   s  (first rotary element) in place of the first ring gear  21   r  (second rotary element) of the Ravigneaux type planetary gear mechanism  25 . In the automatic transmission  20 N, in addition, the brake B 1  makes the second sun gear  22   s  (first securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . Furthermore, the brake B 2  is configured to connect the first ring gear  21   r  (second securable element) of the Ravigneaux type planetary gear mechanism  25  to the transmission case  11 , and disposed around the Ravigneaux type planetary gear mechanism  25 . The thus configured automatic transmission  20 N also allows obtaining functions and effects that are similar to those of the automatic transmission  20 M discussed above. 
       FIG. 27  is a diagram illustrating a schematic configuration of a power transfer device  10 P that includes an automatic transmission  20 P according to another modified aspect of the second embodiment of the present disclosure. The automatic transmission  20 P illustrated in the drawing corresponds to the automatic transmission  20 M described above, and in the automatic transmission  20 P the Ravigneaux type planetary gear mechanism  25  has been replaced with a CR-CR type composite planetary gear mechanism  250  constituted by combining the single-pinion type first and second planetary gears  21  and  22  with each other. As illustrated in the drawing, the first drive gear (externally toothed gear)  26  of the first gear train G 1  is always coupled coaxially with the first ring gear  21   r  and the second carrier  22   c  of the composite planetary gear mechanism  250 . The first ring gear  21   r  and the second carrier  22   c  function as an output element of the composite planetary gear mechanism  250 . In addition, the second drive gear (externally toothed gear)  28  of the second gear train G 2  is always coupled coaxially with the first carrier  21   c  and the second ring gear  22   r  (second rotary element) of the composite planetary gear mechanism  250 . In the example illustrated in  FIG. 27 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . 
     In addition, the clutch C 1  of the automatic transmission  20 P connects and disconnects the input shaft  20   i  (third sun gear  23   s ) and the second sun gear  22   s  (fourth rotary element) of the composite planetary gear mechanism  250  to and from each other. The clutch C 2  connects and disconnects the input shaft  20   i  (third sun gear  23   s ) and the first carrier  21   c  and the second ring gear  22   r  (second rotary element) of the composite planetary gear mechanism  250  to and from each other. The brake B 1  makes the third carrier  23   c  of the third planetary gear  230  and the first sun gear  21   s  (first securable element) of the composite planetary gear mechanism  250  stationary with respect to (connects the third carrier  23   c  and the first sun gear  21   s  to) the transmission case  11  so as to be non-rotatable, and makes the third carrier  23   c  and the first sun gear  21   s  non-stationary with respect to the transmission case  11 . The brake B 2  makes the first carrier  21   c  and the second ring gear  22   r  (second securable element) of the composite planetary gear mechanism  250  stationary with respect to the transmission case  11  by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . The brake B 3  makes the third ring gear  23   r  of the third planetary gear  230  stationary with respect to (connects the third ring gear  23   r  to) the transmission case  11  so as to be non-rotatable, and makes the third ring gear  23   r  non-stationary with respect to the transmission case  11 . The clutch C 5  connects and disconnects the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) to and from each other. 
     In the automatic transmission  20 P, according to the order of arrangement on the velocity diagram illustrated in  FIG. 28 , the first sun gear  21   s  of the composite planetary gear mechanism  250  is defined as a first rotary element of the automatic transmission  20 P, the first carrier  21   c  and the second ring gear  22   r  are defined as a second rotary element of the automatic transmission  20 P, the first ring gear  21   r  and the second carrier  22   c  are defined as a third rotary element of the automatic transmission  20 P, and the second sun gear  22   s  is defined as a fourth rotary element of the automatic transmission  20 P. In addition, the third sun gear  23   s  is defined as a fifth rotary element of the automatic transmission  20 P, the third carrier  23   c  is defined as a sixth rotary element of the automatic transmission  20 P, and the third ring gear  23   r  is defined as a seventh rotary element of the automatic transmission  20 P. 
     With the automatic transmission  20 P configured as discussed above, the first to ninth forward speeds and the reverse speed can be established by engaging and disengaging the clutches C 1 , C 2 , and C 5  and the brakes B 1 , B 2 , and B 3 . That is, also with the automatic transmission  20 P, three shift speeds (third, fifth, and seventh forward speeds) can be added to the speed change device to which the first and second gear trains G 1  and G 2  and the clutch C 5  have not been added. As a result, with the automatic transmission  20 P, by the addition of intermediate shift speeds (third, fifth, and seventh forward speeds), the step ratios can be optimized (an increase in the step ratios can be suppressed), which makes it possible to improve the acceleration performance at each shift speed and the shifting feeling. Thus, also with the automatic transmission  20 P, the drivability can be improved well along with improving the fuel efficiency of the vehicle by increasing the number of shift speeds. 
     In addition, by adopting the CR-CR type composite planetary gear mechanism  250  which is constituted by combining the single-pinion type first and second planetary gears  21  and  22  with each other, it is possible to further improve the power transfer efficiency of the automatic transmission  20 P by reducing a meshing loss between the rotary elements of the composite planetary gear mechanism  250 , and to improve the assemblability while suppressing an increase in the weight of the entire device by reducing the number of components. Also with the automatic transmission  20 P, further, as illustrated in  FIG. 27 , the brake B 2  can be disposed around the axis (second shaft) of the output gear  20   o . Thus, it is possible to suppress an increase in the physical size around the composite planetary gear mechanism  250  (in an end portion remote from the engine). 
       FIG. 29  is a diagram illustrating a schematic configuration of a power transfer device  10 Q that includes an automatic transmission  20 Q according to still another modified aspect of the second embodiment of the present disclosure. In the automatic transmission  20 Q illustrated in the drawing, the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the first sun gear  21   s  of the composite planetary gear mechanism  250  which is a first rotary element of the automatic transmission  20 Q. In the example illustrated in  FIG. 29 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . In the automatic transmission  20 Q, in addition, the brake B 1  makes the first sun gear  21   s  (first securable element) of the composite planetary gear mechanism  250  stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . Furthermore, the brake B 2  is configured to connect the first carrier  21   c  and the second ring gear  22   r  (second securable element) of the composite planetary gear mechanism  250  to the transmission case  11 . The thus configured automatic transmission  20 Q also allows obtaining functions and effects that are similar to those of the automatic transmission  20 P discussed above. 
       FIG. 30  is a diagram illustrating a schematic configuration of a power transfer device  10 R that includes an automatic transmission  20 R according to another modified aspect of the second embodiment of the present disclosure. In the automatic transmission  20 R illustrated in the drawing, the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the second sun gear  22   s  of the composite planetary gear mechanism  250  which is a fourth rotary element of the automatic transmission  20 R. In the example illustrated in  FIG. 30 , the gear ratio gr 2  of the second gear train G 2  is determined to be higher than the gear ratio gr 1  of the first gear train G 1 . The thus configured automatic transmission  20 R also allows obtaining functions and effects that are similar to those of the automatic transmission  20 P discussed above. 
       FIG. 31  is a diagram illustrating a schematic configuration of a power transfer device  10 S that includes an automatic transmission  20 S according to a third embodiment of the present disclosure. Constituent elements of the automatic transmission  20 S that are identical to the elements of the automatic transmission  20  etc. discussed above are given the same numerals to omit redundant descriptions. 
     The automatic transmission  20 S illustrated in  FIG. 31  corresponds to the automatic transmission  20  discussed above, and in the automatic transmission  20 P the third planetary gear  23  and the clutch C 4  have been omitted. In the automatic transmission  20 S, as illustrated in the drawing, the Ravigneaux type planetary gear mechanism  25  is disposed in the transmission case  11  such that the second planetary gear  22  and the first planetary gear  21  are arranged in the order of the second planetary gear  22  and the first planetary gear  21  from the starting device  12  side, that is, the engine side (the right side in  FIG. 11 ). In addition, the first drive gear (externally toothed gear)  26  of the first gear train G 1  is always coupled coaxially with the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25 . The first ring gear  21   r  functions as an output element of the Ravigneaux type planetary gear mechanism  25 . Furthermore, the second drive gear (externally toothed gear)  28  of the second gear train G 2  is always coupled coaxially with the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25 . In the example illustrated in  FIG. 31 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . 
     In addition, the clutch C 1  of the automatic transmission  20 S connects and disconnects the input shaft  20   i  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The clutch C 2  connects and disconnects the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The clutch C 3  connects and disconnects the input shaft  20   i  and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  to and from each other. The brake B 1  makes the first sun gear  21   s  (first securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to (connects the first sun gear  21   s  to) the transmission case  11  so as to be non-rotatable, and makes the first sun gear  21   s  non-stationary with respect to the transmission case  11 . The brake B 2  makes the first carrier  21   c  (second securable element) of the Ravigneaux type planetary gear mechanism  25  stationary with respect to the transmission case  11  so as to be non-rotatable by making the second driven gear  29  of the second gear train G 2  stationary with respect to (connecting the second driven gear  29  to) the transmission case  11  so as to be non-rotatable. The clutch C 5  connects and disconnects the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) to and from each other. 
       FIG. 32  is a velocity diagram illustrating the ratio of the rotational speed of each rotary element to the rotational speed of the input shaft  20   i  (input rotational speed) of the automatic transmission  20 S (note that the rotational speed of the input shaft  20   i  is defined as a value of 1). In addition,  FIG. 33  is an operation table illustrating the relationship between each shift speed of the automatic transmission  20 S and the respective operating states of the clutches C 1  to C 3  and C 5  and the brakes B 1  and B 2 . 
     In the automatic transmission  20 S, according to the order of arrangement on the velocity diagram illustrated in  FIG. 32 , the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  is defined as a first rotary element of the automatic transmission  20 S, the first carrier  21   c  is defined as a second rotary element of the automatic transmission  20 S, the first ring gear  21   r  is defined as a third rotary element of the automatic transmission  20 S, and the second sun gear  22   s  is defined as a fourth rotary element of the automatic transmission  20 S. In the automatic transmission  20 S, the clutches C 1  to C 3  and C 5  and the brakes B 1  and B 2  are engaged and disengaged as illustrated in  FIG. 33  to change the relationship of connection of the first to fourth rotary elements discussed above, which allows establishing seven power transfer paths in the forward rotational direction and one power transfer path in the reverse rotational direction from the input shaft  20   i  to the output gear  20   o , that is, first to seventh forward speeds and a reverse speed. 
     Specifically, the first forward speed of the automatic transmission  20 S is established by engaging the clutch C 1  and the brake B 2  and disengaging the remaining clutches C 2 , C 3 , and C 5  and brake B 1 . That is, to establish the first forward speed, the input shaft  20   i  and the second sun gear  22   s  (fourth rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. The second forward speed is established by engaging the clutch C 1  and the brake B 1  and disengaging the remaining clutches C 2 , C 3 , and C 5  and brake B 2 . That is, to establish the second forward speed, the input shaft  20   i  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. 
     The third forward speed is established by engaging the clutches C 1  and C 5  and disengaging the remaining clutches C 2  and C 3  and brakes B 1  and B 2 . That is, to establish the third forward speed, the input shaft  20   i  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The fourth forward speed is established by engaging the clutches C 1  and C 2  and disengaging the remaining clutches C 3  and C 5  and brakes B 1  and B 2 . That is, to establish the fourth forward speed, the input shaft  20   i  and the second sun gear  22   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 1 . Furthermore, the input shaft  20   i  and the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . 
     The fifth forward speed is established by engaging the clutches C 2  and C 5  and disengaging the remaining clutches C 1  and C 3  and brakes B 1  and B 2 . That is, to establish the fifth forward speed, the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The sixth forward speed is established by engaging the clutch C 2  and the brake B 1  and disengaging the remaining clutches C 1 , C 3 , and C 5  and brake B 2 . That is, to establish the sixth forward speed, the input shaft  20   i  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 2 . Furthermore, the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  is made stationary with respect to the transmission case  11  by the brake B 1  so as to be non-rotatable. 
     The seventh forward speed is established by engaging the clutches C 3  and C 5  and disengaging the remaining clutches C 1  and C 2  and brakes B 1  and B 2 . That is, to establish the seventh forward speed, the input shaft  20   i  and the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 3 . Furthermore, the second driven gear  29  of the second gear train G 2  and the output gear  20   o  (first driven gear  27 ) are connected to each other by the clutch C 5 . The reverse speed is established by engaging the clutch C 3  and the brake B 2  and disengaging the remaining clutches C 1 , C 2 , and C 5  and brake B 1 . That is, to establish the reverse speed, the input shaft  20   i  and the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  are connected to each other by the clutch C 3 . Furthermore, the second driven gear  29  of the second gear train G 2 , that is, the first carrier  21   c  which is coupled to the second driven gear  29  via the second drive gear  28 , is made stationary with respect to the transmission case  11  by the brake B 2  so as to be non-rotatable. 
     As discussed above, with the automatic transmission  20 S, the first to seventh forward speeds and the reverse speed can be established by engaging and disengaging the clutches C 1  to C 3  and C 5  and the brakes B 1  and B 2 . With the automatic transmission  20 S, one of the clutches C 1  to C 3  and the clutch C 5  are engaged to establish the third, fifth, and seventh forward speeds. When the output gear  20   o  is rotated with the clutch C 5  engaged in this way, the first carrier  21   c  (one of the rotary elements), which is coupled via the second drive gear  28  to the second driven gear  29  which is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27 , is rotated with respect to the output gear  20   o  at a rotational speed that matches the gear ratio gr 2  of the second gear train G 2 . When the output gear  20   o  is rotated with the clutch C 5  engaged, in addition, the first ring gear  21   r  which is the output element of the Ravigneaux type planetary gear mechanism  25  is rotated with respect to the output gear  20   o  at a rotational speed that matches the gear ratio gr 1  of the first gear train G 1 . Thus, by engaging one of the clutches C 1  to C 3  and the clutch C 5 , a rotational speed difference that matches the gear ratios gr 1  and gr 2  of the first and second gear trains G 1  and G 2  can be caused between the first ring gear  21   r  and the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25 . Consequently, the automatic transmission  20 S also allows establishing shift speeds other than those obtained by selectively engaging two of the clutches C 1  to C 3  and the brakes B 1  and B 2 . 
     That is, when the clutch C 5  is engaged with torque directly transferred from the input shaft  20   i  to the second sun gear  22   s  (fourth rotary element) of the Ravigneaux type planetary gear mechanism  25  through engagement of the clutch C 1 , the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27  so that the speed of the first carrier  21   c  of the Ravigneaux type planetary gear mechanism  25  can be increased compared to the time when the second forward speed is established and the speed of the first ring gear  21   r  can be reduced compared to the time when the fourth forward speed is established as illustrated in  FIG. 32 . Consequently, it is possible to establish the third forward speed with the gear ratio γ 3  which is lower than the gear ratio γ 2  of the second forward speed and higher than the gear ratio γ 4  of the fourth forward speed. 
     When the clutch C 5  is engaged with torque directly transferred from the input shaft  20   i  to the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25  through engagement of the clutch C 2 , meanwhile, the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27  so that the speed of the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  can be increased compared to the time when the fourth forward speed is established as illustrated in  FIG. 32 . Consequently, it is possible to establish the fifth forward speed with the gear ratio γ 5  which is lower than the gear ratio γ 4  of the fourth forward speed and higher than the gear ratio γ 6  of the sixth forward speed. 
     When the clutch C 5  is engaged with torque directly transferred from the input shaft  20   i  to the first sun gear  21   s  (first rotary element) of the Ravigneaux type planetary gear mechanism  25  through engagement of the clutch C 3 , further, the second driven gear  29  is rotated together with and in the same direction as the output gear  20   o  and the first driven gear  27  so that the speed of the first ring gear  21   r  of the Ravigneaux type planetary gear mechanism  25  can be increased compared to the time when the sixth forward speed is established as illustrated in  FIG. 32 . Consequently, it is possible to establish the seventh forward speed with the gear ratio γ 7  which is lower than the gear ratio γ 6  of the sixth forward speed. 
     As discussed above, with the automatic transmission  20 S in which torque from the input shaft  20   i  is selectively (sequentially) transferred to the second sun gear  22   s , the first carrier  21   c , and the first sun gear  21   s , not the first ring gear  21   r  (output element), of the Ravigneaux type planetary gear mechanism  25 , three shift speeds (third, fifth, and seventh forward speeds) can be added to the speed change device (see JP 2010-216568 A) to which the first and second gear trains G 1  and G 2  and the clutch C 5  have not been added. As a result, with the automatic transmission  20 S, the spread can be further increased by the addition of the seventh forward speed as the highest shift speed to improve the fuel efficiency of the vehicle at a high vehicle speed, in particular. By the addition of intermediate shift speeds (third and fifth forward speeds), further, the step ratios can be optimized (an increase in the step ratios can be suppressed) to improve the shifting feeling. Thus, also with the automatic transmission  20 S, it is possible to improve both the fuel efficiency and the drivability of the vehicle well. Also with the automatic transmission  20 S, in addition, it is possible to increase the number of shift speeds, while suppressing an increase in the size of the entire device or the number of components, by combining the Ravigneaux type planetary gear mechanism  25 , which is a composite planetary gear mechanism with four elements, the first and second gear trains G 1  and G 2 , and the clutch C 5  with each other. Also with the automatic transmission  20 S, further, as illustrated in  FIG. 31 , the brake B 2  can be disposed around the axis (second shaft) of the output gear  20   o . Thus, it is possible to suppress an increase in the physical size around the Ravigneaux type planetary gear mechanism  25 . 
       FIG. 34  is a diagram illustrating a schematic configuration of a power transfer device  10 T that includes an automatic transmission  20 T according to a modified aspect of the third embodiment of the present disclosure. In the automatic transmission  20 T illustrated in the drawing, the Ravigneaux type planetary gear mechanism  25  is disposed in the transmission case  11  such that the first planetary gear  21  and the second planetary gear  22  are arranged in the order of the first planetary gear  21  and the second planetary gear  22  from the starting device  12  side, that is, the engine side (the right side in  FIG. 31 ). In the automatic transmission  20 T, in addition, the second drive gear  28  which constitutes the second gear train G 2  is always coupled to the first sun gear  21   s  (first rotary element) in place of the first carrier  21   c  (second rotary element) of the Ravigneaux type planetary gear mechanism  25 . In the example illustrated in  FIG. 34 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . The thus configured automatic transmission  20 T also allows obtaining functions and effects that are similar to those of the automatic transmission  20 S discussed above. 
       FIG. 35  is a diagram illustrating a schematic configuration of a power transfer device  10 U that includes an automatic transmission  20 U according to another modified aspect of the third embodiment of the present disclosure. The automatic transmission  20 U illustrated in the drawing corresponds to the automatic transmission  20 J discussed above, and in the automatic transmission  20 U the third planetary gear  23  has been omitted. As illustrated in the drawing, the clutch C 1  of the automatic transmission  20 U connects and disconnects the input shaft  20   i  and the first sun gear  21   s  (fourth rotary element) of the composite planetary gear mechanism  250  to and from each other. The thus configured automatic transmission  20 U also allows obtaining functions and effects that are similar to those of the automatic transmission  20 S discussed above. In addition, by adopting the CR-CR type composite planetary gear mechanism  250  which is constituted by combining the single-pinion type first and second planetary gears  21  and  22  with each other, it is possible to further improve the power transfer efficiency of the automatic transmission  20 U by reducing a meshing loss between the rotary elements of the composite planetary gear mechanism  250 , and to improve the assemblability while suppressing an increase in the weight of the entire device by reducing the number of components. 
       FIG. 36  is a diagram illustrating a schematic configuration of a power transfer device  10 V that includes an automatic transmission  20 V according to still another modified aspect of the third embodiment of the present disclosure. In the automatic transmission  20 V illustrated in the drawing, the second drive gear  28  which constitutes the second gear train G 2  is always coupled coaxially with the first sun gear  21   s  of the composite planetary gear mechanism  250  which is a fourth rotary element of the automatic transmission  20 V. In the example illustrated in  FIG. 36 , the gear ratio gr 2  of the second gear train G 2  is determined to be higher than the gear ratio gr 1  of the first gear train G 1 . In the automatic transmission  20 V, in addition, the brake B 2  is configured to connect the first ring gear  21   r  and the second carrier  22   c  (second securable element) of the composite planetary gear mechanism  250  to the transmission case  11 , and disposed around the composite planetary gear mechanism  250 . The thus configured automatic transmission  20 V also allows obtaining functions and effects that are similar to those of the automatic transmission  20 U discussed above. 
       FIG. 37  is a diagram illustrating a schematic configuration of a power transfer device  10 X that includes an automatic transmission  20 X according to another modified aspect of the third embodiment of the present disclosure. In the automatic transmission  20 X illustrated in the drawing, the second drive gear  28  which constitutes the second gear train G 2  is always coupled to the second sun gear  22   s  of the composite planetary gear mechanism  250  which is a first rotary element of the automatic transmission  20 X. In the example illustrated in  FIG. 37 , the gear ratio gr 2  of the second gear train G 2  is determined to be lower than the gear ratio gr 1  of the first gear train G 1 . In the automatic transmission  20 X, in addition, the brake B 1  makes the second sun gear  22   s  (first securable element) of the composite planetary gear mechanism  250  stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . Furthermore, the brake B 2  is configured to connect the first ring gear  21   r  and the second carrier  22   c  (second securable element) of the composite planetary gear mechanism  250  to the transmission case  11 , and disposed around the composite planetary gear mechanism  250 . The thus configured automatic transmission  20 X also allows obtaining functions and effects that are similar to those of the automatic transmission  20 U discussed above. 
     In the automatic transmissions  20  to  20 X discussed above, at least one of the clutches C 1  to C 5  and the brakes B 1  to B 3  may be a meshing engagement element such as a dog clutch or a dog brake. In the automatic transmissions  20  to  20 X, in addition, the gear ratios λ 1  to λ 3  of the first to third planetary gears  21 ,  22 ,  23 , and  230  are not limited to those described above. Furthermore, two winding transmission mechanisms that have different speed ratios may be used in place of the first and second gear trains G 1  and G 2 . In the automatic transmission  20 B illustrated in  FIG. 7 , in addition, the brake B 1  makes the first sun gear  21   s  of the Ravigneaux type planetary gear mechanism  25  stationary with respect to the transmission case  11  so as to be non-rotatable by connecting the second driven gear  29  of the second gear train G 2  to the transmission case  11 . However, the present subject matter is not limited thereto. That is, as in an automatic transmission  203  illustrated in  FIG. 38 , the brake B 1  may be disposed around the input shaft  20   i  (first shaft). Consequently, it is possible to secure the torque capacity and the heat capacity of the brake B 1  well, while suppressing an increase in the number of friction plates (friction materials), by increasing the outside diameter of the friction plates (area of the friction materials) of the brake B 1 . 
     As has been described above, the present disclosure provides a speed change device ( 20  to  20 X) that includes an input member ( 20   i ), an output member ( 20   o ), a composite planetary gear mechanism ( 25 ,  25 W,  250 ) that has at least four rotary elements including an output element ( 21   r ,  21   c ,  21   c  and  22   c ,  21   c  and  22   r ,  21   r  and  22   c ), and at least five engagement elements (B 1 , B 2 , C 1 , C 2 , C 3 ) that each connect and disconnect one of the rotary elements of the composite planetary gear mechanism ( 25 ) and a different one of rotary elements including the input member ( 20   i ) or a stationary member ( 11 ) to and from each other, the speed change device transferring power, which has been transferred to the input member ( 20   i ), to the output member ( 20   o ) with a speed of the power changed. The speed change device includes: a first gear train (G 1 ) that includes a first drive gear ( 26 ) always coupled to the output element of the composite planetary gear mechanism ( 25 ,  25 W,  250 ) and a first driven gear ( 27 ) which is always coupled to the output member ( 20   o ) and to which power is transferred from the first drive gear ( 26 ); a second gear train (G 2 ) that includes a second drive gear ( 28 ) always coupled to one of the rotary elements, not the output element, of the composite planetary gear mechanism ( 25 ) and a second driven gear ( 29 ) that is rotated in the same direction as the first driven gear ( 27 ) by power from the second drive gear ( 28 ), the second gear train having a gear ratio that is different from that of the first gear train; and an output-side engagement element (C 5 ) that connects and disconnects the second driven gear ( 29 ) and the output member ( 20   o ) to and from each other. 
     That is, the speed change device according to the present disclosure corresponds to a transmission which can establish a plurality of shift speeds by selectively engaging at least two of at least five engagement elements, and to which first and second gear trains and an output-side engagement element have been added. The first gear train includes a first drive gear always coupled to the output element of the composite planetary gear mechanism and a first driven gear which is always coupled to the output member and to which power is transferred from the first drive gear. The second gear train includes a second drive gear always coupled to one of the rotary elements, not the output element, of the composite planetary gear mechanism and a second driven gear that is rotated in the same direction as the first driven gear by power from the second drive gear. The second gear train has a gear ratio that is different from that of the first gear train. Further, the output-side engagement element connects and disconnects the second driven gear and the output member to and from each other. 
     In such a speed change device, when the output member is rotated with the output-side engagement element engaged, one of the rotary elements that is coupled via the second drive gear to the second driven gear which is rotated together with the output member is rotated with respect to the output member at a rotational speed that matches the gear ratio of the second gear train. When the output member is rotated with the output-side engagement element engaged, in addition, the output element of the composite planetary gear mechanism is rotated with respect to the output member at a rotational speed that matches the gear ratio of the first gear train. Thus, a rotational speed difference that matches the gear ratios of the first and second gear trains can be caused between the output element of the composite planetary gear mechanism and one of the rotary elements by engaging one of the at least five engagement elements and the output-side engagement element. Consequently, with the speed change device according to the present disclosure, it is possible to establish shift speeds other than those obtained by selectively engaging at least two of the at least five engagement elements. For example, in the case where power from the input member side is selectively transferred to a rotary element, not the output element, of the composite planetary gear mechanism, at least three shift speeds can be added to the speed change device to which the first and second gear trains and the output-side engagement element have not been added. As a result, with the speed change device according to the present disclosure, it is possible to further improve the fuel efficiency and the drivability of a vehicle by increasing the number of shift speeds. 
     The composite planetary gear mechanism ( 25 ,  25 W,  250 ) may have a first rotary element ( 21   s ,  22   s ,  21   s ,  22   s ,  21   s ), a second rotary element ( 21   c ,  21   r ,  22   r ,  21   r  and  22   c ,  21   c  and  22   r ), a third rotary element ( 21   r ,  21   c ,  21   c  and  22   c ,  21   c  and  22   r ,  21   r  and  22   c ), and a fourth rotary element ( 22   s ,  21   s ,  21   r  and  22   s ,  21   s ,  22   s ) that are arranged sequentially in accordance with a gear ratio; and the output element may be the third rotary element, and the one of the rotary elements may be the first, second, or fourth rotary element. It is possible to increase the number of shift speeds, while suppressing an increase in the size of the entire device or the number of components, by combining the composite planetary gear mechanism with four elements, the first and second gear trains, and the output-side engagement element with each other. 
     The five engagement elements may include: a first engagement element (B 1 ) that connects the first rotary element to the stationary member ( 11 ) to make the first rotary element stationary so as to be non-rotatable, and that disconnects the first rotary element and the stationary member ( 11 ) from each other; a second engagement element (B 2 ) that connects the second rotary element to the stationary member ( 11 ) to make the second rotary element stationary so as to be non-rotatable, and that disconnects the second rotary element and the stationary member ( 11 ) from each other; a third engagement element (C 1 ) that allows and cancels transfer of power from an input member side to the fourth rotary element; a fourth engagement element (C 2 ) that allows and cancels transfer of power from the input member side to the second rotary element; and a fifth engagement element (C 3 , B 3 ) that allows and cancels transfer of power from the input member side to the first rotary element. Consequently, it is possible to selectively transfer power from the input member side to the first, second, and fourth rotary elements by selectively engaging the third, fourth, and fifth engagement elements. 
     The speed change device ( 20 ,  20 B,  20 C,  20 D,  20 E,  20 F) may further include a planetary gear ( 23 ) that has a fifth rotary element ( 23   s ), a sixth rotary element ( 23   r ), and a seventh rotary element ( 23   c ) arranged sequentially in accordance with a gear ratio, and a sixth engagement element; one of the fifth and seventh rotary elements ( 23   s ,  23   c ) may be always connected to the stationary member ( 11 ), and the other may be always coupled to the input member ( 20   i ); the third engagement element (C 1 ) may connect and disconnect the fourth rotary element and the sixth rotary element to and from each other; the fourth engagement element (C 2 ) may connect and disconnect the second rotary element and the input member to and from each other; the fifth engagement element (C 3 ) may connect and disconnect the first rotary element and the sixth rotary element to and from each other; and the sixth engagement element (C 4 ) may connect and disconnect the first rotary element and the input member to and from each other. Such a speed change device corresponds to a speed change device which can establish first to eighth forward speeds by selectively engaging two of the first to sixth engagement elements and to which the first and second gear trains and the output-side engagement element have been added. Thus, the speed change device can establish first to twelfth, first to eleventh, first to tenth, or first to ninth forward speeds. Consequently, with the number of shift speeds increased, it is possible to improve both the fuel efficiency and the drivability of the vehicle significantly well. 
     Specifically, first to twelfth forward speeds and a reverse speed can be established by engaging the first to sixth engagement elements and the output-side engagement element as follows. That is, a first forward speed is established by engaging the second and third engagement elements (B 2 , C 1 ). A second forward speed is established by engaging the first and third engagement elements (B 1 , C 1 ). A third forward speed is established by engaging the third engagement element (C 1 ) and the output-side engagement element (C 5 ). A fourth forward speed is established by engaging the third and fifth engagement elements (C 1 , C 3 ). A fifth forward speed is established by engaging the third and sixth engagement elements (C 1 , C 4 ). A sixth forward speed is established by engaging the third and fourth engagement elements (C 1 , C 2 ). A seventh forward speed is established by engaging the fifth engagement element (C 3 ) and the output-side engagement element (C 5 ). An eighth forward speed is established by engaging the fourth and sixth engagement elements (C 2 , C 4 ). A ninth forward speed is established by engaging the fourth engagement element (C 2 ) and the output-side engagement element (C 5 ). A tenth forward speed is established by engaging the fourth and fifth engagement elements (C 2 , C 3 ). An eleventh forward speed is established by engaging the first and fourth engagement elements (B 1 , C 2 ). A twelfth forward speed is established by engaging the sixth engagement element (C 4 ) and the output-side engagement element (C 5 ). A reverse speed is established by engaging the second and fifth engagement elements (B 2 , C 3 ). 
     First to eleventh forward speeds and reverse speeds can be established by engaging the first to sixth engagement elements and the output-side engagement element as follows. That is, a first forward speed is established by engaging the second and third engagement elements (B 2 , C 1 ). A second forward speed is established by engaging the first and third engagement elements (B 1 , C 1 ). A third forward speed is established by engaging the third engagement element (C 1 ) and the output-side engagement element (C 5 ). A fourth forward speed is established by engaging the third and fifth engagement elements (C 1 , C 3 ). A fifth forward speed is established by engaging the third and sixth engagement elements (C 1 , C 4 ). A sixth forward speed is established by engaging the third and fourth engagement elements (C 1 , C 2 ). A seventh forward speed is established by engaging the fourth and sixth engagement elements (C 2 , C 4 ). An eighth forward speed is established by engaging the fourth engagement element (C 2 ) and the output-side engagement element (C 5 ). A ninth forward speed is established by engaging the fourth and fifth engagement elements (C 2 , C 3 ). A tenth forward speed is established by engaging the first and fourth engagement elements (B 1 , C 2 ). An eleventh forward speed is established by engaging the sixth engagement element (C 4 ) and the output-side engagement element (C 5 ). A first reverse speed is established by engaging the second and fifth engagement elements (B 2 , C 3 ). A second reverse speed is established by engaging the second and sixth engagement elements (B 2 , C 4 ). 
     First to tenth forward speeds and a reverse speed can be established by engaging the first to sixth engagement elements and the output-side engagement element as follows. That is, a first forward speed is established by engaging the second and third engagement elements (B 2 , C 1 ). A second forward speed is established by engaging the first and third engagement elements. A third forward speed is established by engaging the third and fifth engagement elements (C 1 , C 3 ). A fourth forward speed is established by engaging the third and sixth engagement elements (C 1 , C 4 ). A fifth forward speed is established by engaging the third and fourth engagement elements (C 1 , C 2 ). A sixth forward speed is established by engaging the fourth and sixth engagement elements (C 2 , C 4 ). A seventh forward speed is established by engaging the fourth engagement element (C 2 ) and the output-side engagement element (C 5 ). An eighth forward speed is established by engaging the fourth and fifth engagement elements (C 2 , C 3 ). A ninth forward speed is established by engaging the first and fourth engagement elements (B 1 , C 2 ). A tenth forward speed is established by engaging the sixth engagement element (C 4 ) and the output-side engagement element (C 5 ). A reverse speed is established by engaging the second and fifth engagement elements (B 2 , C 3 ). 
     First to ninth forward speeds and a reverse speed can be established by engaging the first to sixth engagement elements and the output-side engagement element as follows. That is, a first forward speed is established by engaging the second and third engagement elements (B 2 , C 1 ). A second forward speed is established by engaging the first and third engagement elements (B 1 , C 1 ). A third forward speed is established by engaging the third and fifth engagement elements (C 1 , C 3 ). A fourth forward speed is established by engaging the third and sixth engagement elements (C 1 , C 4 ). A fifth forward speed is established by engaging the third and fourth engagement elements (C 1 , C 2 ). A sixth forward speed is established by engaging the fourth and sixth engagement elements (C 2 , C 4 ). A seventh forward speed is established by engaging the fourth engagement element (C 2 ) and the fifth engagement element (C 3 ). An eighth forward speed is established by engaging the first and fourth engagement elements (B 1 , C 2 ). A ninth forward speed is established by engaging the sixth engagement element (C 4 ) and the output-side engagement element (C 5 ). A reverse speed is established by engaging the second and fifth engagement elements (B 2 , C 3 ). 
     The planetary gear may be a double-pinion type planetary gear that has a third sun gear ( 23   s ), a third ring gear ( 23   r ), and a third carrier ( 23   c ) that rotatably and revolvably holds a plurality of sets of two pinion gears ( 23   pa ,  23   pb ) meshed with each other, one of the pinion gears being meshed with the third sun gear ( 23   s ) and the other being meshed with the third ring gear ( 23   r ), the fifth rotary element may be the third sun gear ( 23   s ), the sixth rotary element may be the third ring gear ( 23   r ), and the seventh rotary element may be the third carrier ( 23   c ). 
     The speed change device ( 20 G,  20 H,  20 I,  20 J,  20 K,  20 L) may further include a planetary gear ( 230 ,  23 ) that has a fifth rotary element ( 23   s ), a sixth rotary element ( 23   c ,  23   r ), and a seventh rotary element ( 23   r ,  23   c ) arranged sequentially in accordance with a gear ratio; one of the fifth and seventh rotary elements may be always connected to the stationary member ( 11 ), and the other may be always coupled to the input member ( 20   i ); the third engagement element (C 1 ) may connect and disconnect the fourth rotary element and the sixth rotary element to and from each other; the fourth engagement element (C 2 ) may connect and disconnect the second rotary element and the input member to and from each other; and the fifth engagement element (C 3 ) may connect and disconnect the first rotary element and the sixth rotary element to and from each other. Such a speed change device corresponds to a speed change device which can establish first to sixth forward speeds by selectively engaging two of the first to fifth engagement elements and to which the first and second gear trains and the output-side engagement element have been added. Thus, the speed change device can establish the first to ninth forward speeds. Consequently, with the number of shift speeds increased, it is possible to improve both the fuel efficiency and the drivability of the vehicle. 
     With the speed change device, first to ninth forward speeds and a reverse speed can be established by engaging the first to fifth engagement elements and the output-side engagement element as follows. That is, a first forward speed is established by engaging the second and third engagement elements (B 2 , C 1 ). A second forward speed is established by engaging the first and third engagement elements (B 1 , C 1 ). A third forward speed is established by engaging the third engagement element (C 1 ) and the output-side engagement element (C 5 ). A fourth forward speed is established by engaging the third and fifth engagement elements (C 1 , C 3 ). A fifth forward speed is established by engaging the fifth engagement element (C 3 ) and the output-side engagement element (C 5 ). A sixth forward speed is established by engaging the third and fourth engagement elements (C 1 , C 2 ). A seventh forward speed is established by engaging the fourth engagement element (C 2 ) and the output-side engagement element (C 5 ). An eighth forward speed is established by engaging the fourth and fifth engagement elements (C 2 , C 3 ). A ninth forward speed is established by engaging the first and fourth engagement elements (B 1 , C 2 ). A reverse speed is established by engaging the second and fifth engagement elements (B 2 , C 3 ). 
     First to ninth forward speeds and a reverse speed can be established also by engaging the first to fifth engagement elements and the output-side engagement element as follows. That is, a first forward speed is established by engaging the second and third engagement elements (B 2 , C 1 ). A second forward speed is established by engaging the first and third engagement elements (B 1 , C 1 ). A third forward speed is established by engaging the third engagement element (C 1 ) and the output-side engagement element (C 5 ). A fourth forward speed is established by engaging the third and fifth engagement elements (C 1 , C 3 ). A fifth forward speed is established by engaging the third and fourth engagement elements (C 1 , C 2 ). A sixth forward speed is established by engaging the fourth and fifth engagement elements (C 2 , C 3 ). A seventh forward speed is established by engaging the fourth engagement element (C 2 ) and the output-side engagement element (C 5 ). An eighth forward speed is established by engaging the first and fourth engagement elements (B 1 , C 2 ). A ninth forward speed is established by engaging the fifth engagement element (C 3 ) and the output-side engagement element (C 5 ). A reverse speed is established by engaging the second and fifth engagement elements (B 2 , C 3 ). 
     The speed change device ( 20 M,  20 N,  20 P,  20 Q,  20 R) may further include a planetary gear ( 23 ) that has a fifth rotary element ( 23   s ), a sixth rotary element ( 23   c ), and a seventh rotary element ( 23   r ) arranged sequentially in accordance with a gear ratio; the fifth rotary element ( 23   s ) may be always coupled to the input member ( 20   i ); the third engagement element (C 1 ) may connect and disconnect the fourth rotary element and the input member ( 20   i ) to and from each other; the fourth engagement element (C 2 ) may connect and disconnect the second rotary element and the input member ( 20   i ) to and from each other; and the fifth engagement element (B 3 ) may connect the seventh rotary element ( 23   r ) to the stationary member ( 11 ) to make the seventh rotary element stationary so as to be non-rotatable, and disconnect the seventh rotary element and the stationary member from each other. Such a speed change device also corresponds to a speed change device which can establish first to sixth forward speeds by selectively engaging two of the first to fifth engagement elements and to which the first and second gear trains and the output-side engagement element have been added. Thus, the speed change device can establish the first to ninth forward speeds. Consequently, with the number of shift speeds increased, it is possible to improve both the fuel efficiency and the drivability of the vehicle. 
     With the speed change device, first to ninth forward speeds and a reverse speed can be established by engaging the first to fifth engagement elements and the output-side engagement element as follows. That is, a first forward speed is established by engaging the second and third engagement elements (B 2 , C 1 ). A second forward speed is established by engaging the first and third engagement elements (B 1 , C 1 ). A third forward speed is established by engaging the fifth engagement element (B 3 ) and the output-side engagement element (C 5 ). A fourth forward speed is established by engaging the third and fifth engagement elements (C 1 , B 3 ). A fifth forward speed is established by engaging the third engagement element (C 1 ) and the output-side engagement element (C 5 ). A sixth forward speed is established by engaging the third and fourth engagement elements (C 1 , C 2 ). A seventh forward speed is established by engaging the fourth engagement element (C 2 ) and the output-side engagement element (C 5 ). An eighth forward speed is established by engaging the fourth and fifth engagement elements (C 2 , B 3 ). A ninth forward speed is established by engaging the first and fourth engagement elements (B 1 , C 2 ). A reverse speed is established by engaging the second and fifth engagement elements (B 2 , B 3 ). 
     The planetary gear may be a single-pinion type planetary gear that has a third sun gear ( 23   s ), a third ring gear ( 23   r ), and a third carrier ( 23   c ) that rotatably and revolvably holds a plurality of third pinion gears ( 23   p ) meshed with the third sun gear ( 23   s ) and the third ring gear ( 23   r ), the fifth rotary element may be the third sun gear ( 23   s ) which is always connected to the stationary member ( 11 ), the sixth rotary element may be the third carrier ( 23   c ), and the seventh rotary element may be the third ring gear ( 23   r ). 
     The planetary gear may be a double-pinion type planetary gear that has a third sun gear ( 23   s ), a third ring gear ( 23   r ), and a third carrier ( 23   c ) that rotatably and revolvably holds a plurality of sets of two pinion gears ( 23   pa ,  23   pb ) meshed with each other, one of the pinion gears being meshed with the third sun gear ( 23   s ) and the other being meshed with the third ring gear ( 23   r ), the fifth rotary element may be the third sun gear ( 23   s ), the sixth rotary element may be the third ring gear ( 23   r ), and the seventh rotary element may be the third carrier ( 23   c ) which is always connected to the stationary member ( 11 ). 
     The third engagement element (C 1 ) may connect and disconnect the fourth rotary element and the input member ( 20   i ) to and from each other; the fourth engagement element (C 2 ) may connect and disconnect the second rotary element and the input member ( 20   i ) to and from each other; and the fifth engagement element (C 3 ) may connect and disconnect the first rotary element and the input member ( 20   i ) to and from each other. Such a speed change device ( 20 S,  20 T,  20 U,  20 V,  20 X) corresponds to a speed change device which can establish first to fourth forward speeds by selectively engaging two of the first to fifth engagement elements and to which the first and second gear trains and the output-side engagement element have been added. Thus, the speed change device can establish the first to seventh forward speeds. Consequently, with the low-cost speed change device, it is possible to improve the fuel efficiency and the drivability of a vehicle by increasing the number of shift speeds. 
     With the speed change device, first to seventh forward speeds and a reverse speed can be established by engaging the first to fifth engagement elements and the output-side engagement element as follows. That is, a first forward speed is established by engaging the second and third engagement elements (B 2 , C 1 ). A second forward speed is established by engaging the first and third engagement elements (B 1 , C 1 ). A third forward speed is established by engaging the third engagement element (C 1 ) and the output-side engagement element (C 5 ). A fourth forward speed is established by engaging the third and fourth engagement elements (C 1 , C 2 ). A fifth forward speed is established by engaging the fourth engagement element (C 2 ) and the output-side engagement element (C 5 ). A sixth forward speed is established by engaging the first and fourth engagement elements (B 1 , C 2 ). A seventh forward speed is established by engaging the fifth engagement element (C 3 ) and the output-side engagement element (C 5 ). A reverse speed is established by engaging the second and fifth engagement elements (B 2 , C 3 ). 
     The composite planetary gear mechanism ( 25 ) may be a Ravigneaux type planetary gear mechanism that has a first sun gear ( 21   s ), a second sun gear ( 22   s ), a first pinion gear ( 21   p ) meshed with the first sun gear ( 21   s ), a second pinion gear ( 22   p ) meshed with the second sun gear ( 22   s ) and meshed with the first pinion gear ( 21   p ), a first carrier ( 21   c ) that rotatably and revolvably holds the first and second pinion gears ( 21   p ,  22   p ), and a first ring gear ( 21   r ) meshed with the second pinion gear ( 22   p ), the first rotary element may be the first sun gear ( 21   s ), the second rotary element may be the first carrier ( 21   c ), the third rotary element may be the first ring gear ( 21   r ), and the fourth rotary element may be the second sun gear ( 22   s ). Consequently, by adopting a Ravigneaux type planetary gear mechanism as the composite planetary gear mechanism, it is possible to improve the assemblability while suppressing an increase in the weight of the entire device by reducing the number of components. 
     The composite planetary gear mechanism ( 25 ) may be a Ravigneaux type planetary gear mechanism that has a first sun gear ( 21   s ), a second sun gear ( 22   s ), a first pinion gear ( 21   p ) meshed with the first sun gear ( 21   s ), a second pinion gear ( 22   p ) meshed with the second sun gear ( 22   s ) and meshed with the first pinion gear ( 21   p ), a first carrier ( 21   c ) that rotatably and revolvably holds the first and second pinion gears ( 21   p ,  22   p ), and a first ring gear ( 21   r ) meshed with the second pinion gear ( 22   p ); and the first rotary element may be the second sun gear ( 22   s ), the second rotary element may be the first ring gear ( 21   r ), the third rotary element may be the first carrier ( 21   c ), and the fourth rotary element may be the first sun gear ( 21   s ). 
     The composite planetary gear mechanism ( 25 W) may include a single-pinion type first planetary gear ( 21 ) that has a first sun gear ( 21   s ), a first ring gear ( 21   r ), and a first carrier ( 21   c ) that rotatably and revolvably holds a plurality of first pinion gears ( 21   p ) meshed with the first sun gear ( 21   s ) and the first ring gear ( 21   r ), and a single-pinion type second planetary gear ( 22 ) that has a second sun gear ( 22   s ), a second ring gear ( 22   r ), and a second carrier ( 22   c ) that rotatably and revolvably holds a plurality of second pinion gears ( 22   p ) meshed with the second sun gear ( 22   s ) and the second ring gear ( 22   r ); and the first rotary element may be the first sun gear ( 21   s ), the second rotary element may be the second ring gear ( 22   r ), the third rotary element may be the first and second carriers ( 21   c ,  22   c ) which are always coupled to each other, and the fourth rotary element may be the first ring gear ( 21   r ) and the second sun gear ( 22   s ) which are always coupled to each other. Also by adopting such a composite planetary gear mechanism which is constituted by combining the single-pinion type first and second planetary gears with each other, it is possible to further improve the assemblability while suppressing an increase in the weight of the speed change device by reducing the number of components. With such a composite planetary gear mechanism, additionally, the second planetary gear can be disposed so as to surround the first planetary gear. Thus, it is possible to further shorten the axial length of the speed change device. 
     In this case, the first ring gear ( 21   r ) and the second sun gear ( 22   s ) may be integrated with each other; and the composite planetary gear mechanism ( 25 W) may be disposed such that the first pinion gears ( 21   p ) and the second pinion gears ( 22   p ) at least partially overlap each other in an axial direction as seen in a radial direction. 
     The composite planetary gear mechanism ( 250 ) may include a single-pinion type first planetary gear ( 21 ) that has a first sun gear ( 21   s ), a first ring gear ( 21   r ), and a first carrier ( 21   c ) that rotatably and revolvably holds a plurality of first pinion gears ( 21   p ) meshed with the first sun gear ( 21   s ) and the first ring gear ( 21   r ), and a single-pinion type second planetary gear ( 22 ) that has a second sun gear ( 22   s ), a second ring gear ( 22   r ), and a second carrier ( 22   c ) that rotatably and revolvably holds a plurality of second pinion gears ( 22   p ) meshed with the second sun gear ( 22   s ) and the second ring gear ( 22   r ); and the first rotary element may be the second sun gear ( 22   s ), the second rotary element may be the first ring gear ( 21   r ) and the second carrier ( 22   c ) which are always coupled to each other, the third rotary element may be the first carrier ( 21   c ) and the second ring gear ( 22   r ) which are always coupled to each other, and the fourth rotary element may be the first sun gear ( 21   s ). Also by adopting the so-called CR-CR type composite planetary gear mechanism, which includes two single-pinion type planetary gears, as the composite planetary gear mechanism in this way, it is possible to further improve the power transfer efficiency of the speed change device by reducing a meshing loss between the rotary elements of the composite planetary gear mechanism, and to improve the assemblability while suppressing an increase in the weight of the entire device by reducing the number of components. 
     The composite planetary gear mechanism ( 250 ) may include a single-pinion type first planetary gear ( 21 ) that has a first sun gear ( 21   s ), a first ring gear ( 21   r ), and a first carrier ( 21   c ) that rotatably and revolvably holds a plurality of first pinion gears ( 21   p ) meshed with the first sun gear ( 21   s ) and the first ring gear ( 21   r ), and a single-pinion type second planetary gear ( 22 ) that has a second sun gear ( 22   s ), a second ring gear ( 22   r ), and a second carrier ( 22   c ) that rotatably and revolvably holds a plurality of second pinion gears ( 22   p ) meshed with the second sun gear ( 22   s ) and the second ring gear ( 22   r ); and the first rotary element may be the first sun gear ( 21   s ), the second rotary element may be the first carrier ( 21   c ) and the second ring gear ( 22   r ) which are always coupled to each other, the third rotary element may be the first ring gear ( 21   r ) and the second carrier ( 22   c ) which are always coupled to each other, and the fourth rotary element may be the second sun gear ( 21   s ). 
     The first drive gear ( 26 ) may be an externally toothed gear that is rotated together with the output element of the composite planetary gear mechanism ( 25 ), and the first driven gear ( 27 ) may be an externally toothed gear that is meshed with the first drive gear ( 26 ) and that is rotated together with the output member ( 20   o ); and the second drive gear ( 28 ) may be an externally toothed gear that is rotated together with the one of the rotary elements of the composite planetary gear mechanism ( 25 ), and the second driven gear ( 29 ) may be an externally toothed gear meshed with the second drive gear ( 28 ). Consequently, it is possible to couple the output element and one of the rotary elements of the composite planetary gear mechanism to the output member while suppressing an increase in the size of the speed change device. 
     One of the gear ratio of the first gear train and the gear ratio of the second gear train may be 1.00. 
     The output member may transfer power to a differential gear coupled to front wheels of a vehicle. 
     The composite planetary gear mechanism ( 25 ,  25 W,  250 ) may include a first planetary gear ( 21 ) and a second planetary gear ( 22 ) that each have three rotary elements; and one of two rotary elements of the first planetary gear ( 21 ) may be always coupled to one of two rotary elements of the second planetary gear ( 22 ), and the other of the two rotary elements of the first planetary gear ( 21 ) may be always coupled to the other of the two rotary elements of the second planetary gear ( 22 ). 
     The at least five engagement elements (B 1 , B 2 , C 1 , C 2 , C 3 , C 4 ) may include a plurality of clutches (C 1 , C 2 , C 3 , C 4 ) that each connect and disconnect one of the rotary elements, not the output element, of the composite planetary gear mechanism ( 25 ,  25 W,  250 ) and the different one of the rotary elements including the input member ( 20   i ) to and from each other; and the speed change device may establish a plurality of forward speeds and at least one reverse speed by selectively engaging the at least five engagement elements (B 1 , B 2 , C 1 , C 2 , C 3 , C 4 ), and establish at least two forward speeds that are different from the plurality of forward speeds by engaging one of the plurality of clutches (C 1 , C 2 , C 3 , C 4 ) and the output-side engagement element (C 5 ). 
     The plurality of clutches (C 1 , C 2 , C 3 , C 4 ) may each connect and disconnect the one of the rotary elements, not the output element, of the composite planetary gear mechanism ( 25 ,  25 W,  250 ) and one of the input member ( 20   i ) and the different one of the rotary elements that is rotated at a rotational speed that is lower than that of the input member ( 20   i ) to and from each other. 
     The present disclosure is not limited to the embodiments described above in any way, and it is a matter of course that they may be modified in various ways without departing from the range of the extension of the present disclosure. Furthermore, the embodiments described above are merely specific forms described in the “SUMMARY” section, and does not limit the elements thereof. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure is applicable, for example, to the speed change device manufacturing industry etc.