Patent Publication Number: US-2003232675-A1

Title: Power transmission interruption apparatus

Description:
[0001] The disclosure of Japanese Patent Application No. 2002-177505 filed on Jun. 18, 2002, including the specification, drawings and abstract, is incorporated herein by reference in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The invention relates to a power transmission interruption apparatus, and more particularly to improvement in a power transmission interruption apparatus in which a pair of hydraulic cylinders that causes a pair of friction engaging devices to be engaged is provided on a common rotation member so as to be integrally rotated around an axis.  
       [0004] b  2 . Description of the Related Art  
       [0005] An automatic transmission for a vehicle using plural planetary gears, clutches, and brakes is frequently employed. An example of such an automatic transmission is disclosed in Japanese Patent Laid-Open Publication No. 2001-304355.  
       [0006] The transmission includes (a) a rotation member (an input shaft  2 ), (b) a first hydraulic cylinder, (c) a first friction engaging device (a clutch C 2 ), (d) a second hydraulic cylinder, and (e) a second friction engaging device (a clutch C 3 ).  
       [0007] (a) The rotation member (the input shaft  2 ) rotates around an axis.  
       [0008] (b) The first hydraulic cylinder is provided coaxially and integrally with the rotation member in (a), and is rotated around the axis of the rotation member in (a). In addition, the first hydraulic cylinder moves a piston ( 15 ) in a first direction which is in parallel with the axis when hydraulic fluid is supplied into a pressure chamber.  
       [0009] (c) The first friction engaging device (the clutch C 2 ) includes plural friction members provided on both of the rotation member and a first connecting member ( 4   b ) that are rotatable with respect to each other around the axis. The plural friction members provided on the rotation member are non-rotatable with respect thereto. Also, the plural friction members provided on the first connecting member ( 4   b ) are non-rotatable with respect thereto. The first friction engaging device (the clutch C 2 ) connects the rotation member and the first connecting member when the piston of the first hydraulic cylinder is moved in the first direction such that the friction members are engaged.  
       [0010] (d) The second hydraulic cylinder is provided coaxially and integrally with the rotation member at a position adjacent to the first hydraulic cylinder in the first direction, and is rotated around the axis. In addition, the second hydraulic cylinder moves a piston ( 31 ) when hydraulic fluid is supplied into a pressure chamber.  
       [0011] (e) The second friction engaging device (the clutch C 3 ) includes plural friction members provided on the rotation member and a second connecting member (an intermediate shaft  3 ) that are rotatable with respect to each other around the axis. The friction members provided on the rotation member are non-rotatable thereto. Also, the friction members provided on the second connecting member are non-rotatable with respect thereto. The second friction engaging device (the clutch C 3 ) connects the rotation member and the second connecting member when a piston of the second hydraulic cylinder is moved such that the friction members are engaged.  
       [0012] A cancel plate ( 21 ,  34 ) is provided in each of the first hydraulic cylinder and the second hydraulic cylinder such that centrifugal hydraulic pressure due to the rotation of the hydraulic cylinders is cancelled.  
       [0013] However, in the case where the cancel plate is provided in each of the hydraulic cylinders such that the centrifugal hydraulic pressure is cancelled in this manner, the number of components increases, which increases the weight and manufacturing cost. In addition, a linear dimension in the axial direction increases, which increases an arrangement space.  
       SUMMARY OF THE INVENTION  
       [0014] In view of the above, it is an object of the invention to configure a power transmission interruption apparatus in which a pair of hydraulic cylinders is provided in a common rotation member so as to be integrally rotated around an axis, and which is compact, light-weight, and inexpensive.  
       [0015] In other words, according to an aspect of the invention, a power transmission interruption apparatus which integrally rotates so as to transmit power includes a rotation member, a first friction engaging device and a second friction engaging device, a first hydraulic cylinder, a second hydraulic cylinder, and a centrifugal hydraulic pressure canceller chamber. The first friction engaging device and the second friction engaging device transmit power. The first hydraulic cylinder is provided coaxially with the rotation member. The first hydraulic cylinder rotates together with the power transmission interruption apparatus, and causes the first friction engaging device to be engaged. The second hydraulic cylinder is provided coaxially with the rotation member and is provided next to the first hydraulic cylinder along to a rotation axis of the rotation member. The second hydraulic cylinder rotates together with the power transmission interruption apparatus, and causes the second friction engaging device to be engaged. The centrifugal hydraulic pressure canceller chamber is formed between a cylinder tube of the second hydraulic cylinder and a piston of the first hydraulic cylinder using the cylinder tube as a cancel plate. The centrifugal hydraulic pressure canceller chamber cancels centrifugal hydraulic pressure in the first hydraulic cylinder, which is generated when hydraulic fluid is introduced into the first hydraulic cylinder.  
       [0016] Also, according to another aspect of the invention, a power transmission interruption apparatus includes a rotation member, a first hydraulic cylinder, a first friction engaging device, a second hydraulic cylinder, a second friction engaging device, and a centrifugal hydraulic pressure canceller chamber. The rotation member is rotated around an axis. The first hydraulic cylinder is provided coaxially and integrally with the rotation member and is rotated around the axis. In addition, the first hydraulic cylinder moves a piston in a first direction which is in parallel with the axis when hydraulic fluid is supplied into a pressure chamber. The first friction engaging device includes at least one friction member provided on each of the rotation member and a first connecting member that are rotatable with respect to each other around the axis. The at least one friction member provided on the rotation member is non-rotatable with respect thereto. The at least one friction member provided on the first connecting member is non-rotatable with respect thereto. The first friction engaging device connects the rotation member and the first connecting member when the piston of the first hydraulic cylinder is moved in the first direction such that the at least one friction member on the rotation member and the at least one friction member on the first connecting member are engaged. The second hydraulic cylinder is provided coaxially and integrally with the rotation member at a position adjacent to the first hydraulic cylinder in the first direction, and is rotated around the axis. In addition, the second hydraulic cylinder moves a piston when hydraulic fluid is supplied into a pressure chamber. The second friction engaging device includes at least one friction member provided on each of the rotation member and a second connecting member that are rotatable with respect to each other around the axis. The at least one friction member provided on the rotation member is non-rotatable with respect thereto. The at least one friction member provided on the second connecting member is non-rotatable with respect thereto. The second friction engaging device connects the rotation member and the second connecting member when a piston of the second hydraulic cylinder is moved such that the friction members are engaged. The centrifugal hydraulic pressure canceller chamber is formed between a cylinder tube forming a pressure chamber of the second hydraulic cylinder and the piston of the first hydraulic cylinder using the cylinder tube as a cancel plate. The centrifugal hydraulic pressure canceller chamber cancels centrifugal hydraulic pressure in a pressure chamber of the first hydraulic cylinder, which is generated when hydraulic fluid is introduced into the pressure chamber of the first hydraulic cylinder. The power transmission interruption apparatus transmits and interrupts power between the rotation member and the first connecting member, and between the rotation member and the second connecting member. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0017]FIG. 1A is a schematic diagram showing an automatic transmission for a vehicle including a power transmission interruption apparatus according to an embodiment of the invention, and FIG. 1B is an operation table showing operation states of clutches and brakes when achieving each shift stage of the automatic transmission for a vehicle;  
     [0018]FIG. 2 is a collinear diagram concerning the embodiment in FIG. 1;  
     [0019]FIG. 3 is a cross sectional view specifically showing clutches C 1 , C 2  of the automatic transmission for a vehicle in FIG. 1; and  
     [0020]FIG. 4 is a cross sectional view showing another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0021] Hereinafter, an embodiment of the invention will be described in detail with reference to accompanying drawings.  
     [0022]FIG. 1A is a schematic diagram showing an automatic transmission for a vehicle  10  to which the invention is applied. FIG. 1B is an operation table describing engagement elements when achieving plural shift stages. The automatic transmission for a vehicle  10  is of transversely-mounted type, and is mounted in a front engine front wheel drive vehicle and the like. The automatic transmission for a vehicle  10  includes a first shift portion  14  and a second shift portion  20  on the same axis. The automatic transmission for a vehicle  10  changes the rotational speed of an input shaft  22  and outputs the changed rotational speed from an output gear  24 . The first shift portion  14  is configured so as to include a first planetary gear device  12  of double pinion type as a main portion. Also, the second shift portion  20  is configured so as to include a second planetary gear device  16  of single pinion type and a third planetary gear device  18  of double pinion type as main portions. The input shaft  22  corresponds to an input member, for example, a turbine shaft of a torque converter which is rotationally driven by a driving power source for running such as an engine.  
     [0023] The automatic transmission for a vehicle  10  is configured so as to be substantially symmetrical with respect to an axis. In FIG. 1A, a lower half portion below the axis is omitted.  
     [0024] The first planetary gear device  12  constituting the first shift portion  14  includes three rotation elements, that is, a sun gear S 1 , a carrier CA 1 , and a ring gear R 1 . In the first planetary gear device  12 , when the sun gear S 1  is connected to the input shaft  22  so as to be rotationally driven, and the carrier CA 1  is fixed to a case  26  so as to be non-rotatable through a third brake B 3 , the rotational speed of the ring gear R 1  as an intermediate output member is reduced with respect to the rotational speed of the input shaft  22  so as to be output. Also, portions of the second planetary gear device  16  and the third planetary gear device  18  which constitute the second shift portion  20  are mutually connected such that four rotation elements RM 1  to RM 4  are formed. More specifically, a sun gear S 3  of the third planetary gear device constitutes the first rotation element RM 1 . Also, a ring gear R 2  of the second planetary gear device  16  and a ring gear R 3  of the third planetary gear device  18  are mutually connected so as to constitute the second rotation element RM 2 . Further, a carrier CA 2  of the second planetary gear device  16  and a carrier CA 3  of the third planetary gear device  18  are mutually connected so as to constitute the third rotation element RM 3 . Furthermore, a sun gear S 2  of the second planetary gear device  16  constitutes the fourth rotation element RM 4 . The second planetary gear device  16  and the third planetary gear device  18  form a Ravigneaux type gear train, in which the carriers CA 2 , CA 3  are constituted by a common member, the ring gears R 2  and R 3  are constituted by a common member, and a pinion gear of the second planetary gear device  16  is also used as a second pinion gear of the third planetary gear device  18 .  
     [0025] The first rotation element RM 1  (the sun gear S 3 ) is selectively connected to the case  26  by a first brake B 1  such that the rotation thereof is stopped. The second rotation element RM 2  (the ring gears R 2 , R 3 ) is connected to the input shaft  22  through a first clutch C 1 , and is selectively fixed to the case  26  by a second brake B 2  such that the rotation thereof is stopped. The fourth rotation element RM 4  (the sun gear S 2 ) is selectively connected to the input shaft  22  through the second clutch C 2 . The first rotation element RM 1  (the sun gear S 3 ) is integrally connected to the ring gear R 1  of the first planetary gear device  12 , which is an intermediate output member. The third rotation element RM 3  (the carriers CA 2 , CA 3 ) is integrally connected to the output gear  24  so as to output the rotation. Each of the first brake B 1  to the third brake B 3 , the first clutch C 1  as the first friction engaging device, and the second clutch C 2  as the second friction engaging device is a multi-plate type hydraulic friction engaging device which is frictionally engaged by the hydraulic cylinder. A one way clutch F is provided between the second rotation element RM 2  and the case  26  so as to be in parallel with the second brake B 2 . The one way clutch F permits the clockwise rotation (that is, the rotation whose direction is the same as that of the rotation of the input shaft  22 ), and prevents the reverse rotation of the second rotation element RM 2 .  
     [0026]FIG. 2 is a collinear diagram showing the rotational speeds of the rotation elements of the first shift portion  14  and the second shift portion  20  using straight lines. A lower horizontal line indicates the rotational speed “0”, and an upper horizontal line indicates the rotational speed “1.0”, that is, the same rotational speed as that of the input shaft  22 . Also, vertical lines concerning the first shift portion  14  indicate the sun gear S 1 , the ring gear R 1 , and the carrier CA 1  from the left side. The intervals therebetween are determined according to a gear ratio ρ1 of the first planetary gear device  12  (that is, the number of the teeth of the sun gear/the number of the teeth of the ring gear). Four vertical lines concerning the second shift portion  20  indicate the first rotation element RM 1  (the sun gear S 3 ), the second rotation element RM 2  (the ring gears R 2 , R 3 ), the third rotation element RM 3  (the carriers CA 2 , CA 3 ), and the fourth rotation element RM 4  (the sun gear S 2 ) from the left side toward the right side. The intervals therebetween are determined according to a gear ratio ρ2 of the second planetary gear device  16  and a gear ratio ρ3 of the third planetary gear device  18 .  
     [0027] As apparent from the above collinear diagram, when the second clutch C 2  and the second brake B 2  are engaged, the fourth rotation element RM 4  is integrally rotated with the input shaft  22 , and the rotation of the second rotation element RM 2  is stopped, the third rotation element RM 3  connected to the output gear  24  is rotated at a first rotational speed. Thus, a first shift stage whose shift ratio is the largest is achieved. When the second clutch C 2  and the first brake B 1  are engaged, the fourth rotation element RM 4  is integrally rotated with the input shaft  22 , and the rotation of the first rotation element RM 1  is stopped, the third rotation element RM 3  is rotated at a second rotational speed. Thus, a second shift stage whose shift ratio is smaller than that of the first shift stage is achieved. When the second clutch C 2  and the third brake B 3  are engaged, the fourth rotation element RM 4  is integrally rotated with the input shaft  22 , and the rotation of the first rotation element RM 1  is reduced through the first shift portion  14 , the third rotation element RM 3  is rotated at a third rotational speed. Thus, a third shift stage whose shift ratio is smaller than that of the second shift stage is achieved. When the first clutch C 1  and the second clutch C 2  are engaged, and the second shift portion  20  is integrally rotated with the input shaft  22 , the third rotation element RM 3  is rotated at a fourth rotational speed, that is the same rotational speed as that of the input shaft  22 . Thus, a fourth shift stage whose shift ratio is smaller than that of the third shift stage is achieved. The shift ratio of the fourth shift stage is 1. When the first clutch C 1  and the third brake B 3  are engaged, the second rotation element RM 2  is integrally rotated with the input shaft  22 , and the first rotation element RM 1  is rotated at a reduced rotational speed through the first shift portion  14 , the third rotation element RM 3  is rotated at a fifth rotational speed. Thus, a fifth shift stage whose shift ratio is smaller than that of the fourth shift stage is achieved. When the first clutch C 1  and the first brake B 1  are engaged, the second rotation element RM 2  is integrally rotated with the input shaft  22 , and the rotation of the first rotation element RM 1  is stopped, the third rotation element RM 3  is rotated at a sixth rotational speed. Thus, a sixth shift stage whose shift ratio is smaller than that of the fifth shift stage is achieved. Also, when the second brake B 2  and the third brake B 3  are engaged, the rotation of the second rotation element RM 2  is stopped, and the first rotation element RM 1  is rotated at a reduced speed through the first shift portion  14 . Thus, the third rotation element RM 3  is reversely rotated at a rotational speed Rev. Thus, a reverse shift stage Rev is achieved.  
     [0028]FIG. 1B is an operation table showing the relation between the shift stages and the operation states of the clutches C 1 , C 2 , and the brakes B 1  to B 3 . In the operation table, a circle indicates engagement, and a double circle indicates engagement which is performed only at the time of engine brake. Since the one way clutch F is provided in parallel with the brake B 2  for achieving the fist shift stage, the brake B 2  does not necessarily need to be engaged at the time of take-off (at the time of acceleration). Also, the shift ratios of the shift stages are appropriately determined according to the gear ratios ρ1, ρ2, and ρ3 of the first planetary gear device  12 , the second planetary gear device  16 , and the third planetary gear device  18 .  
     [0029] Meanwhile, FIG. 3 is a cross sectional view specifically showing a power transmission interruption apparatus  30  which transmits and interrupts power between the input shaft  22  which is the rotation member and the second rotation element RM 2  which is the first connecting member, and between the input shaft  22  and the fourth rotation element RM 4  which is the second connecting member. FIG. 3 shows an upper half portion above the axis O. The power transmission interruption apparatus  30  includes a first hydraulic cylinder  32  which causes the first clutch C 1  to be frictionally engaged, and a second hydraulic cylinder  34  which causes the second clutch C 2  to be frictionally engaged. Each of the first hydraulic cylinder  32  and the second hydraulic cylinder  34  has an annular shape with the input shaft  22  at the center thereof, and is provided coaxially and integrally with the input shaft  22  so as to be integrally rotated around the axis O together with the input shaft  22 . The first hydraulic cylinder  32  corresponds to the first hydraulic cylinder in the first aspect of the invention, and the second hydraulic cylinder  34  corresponds to the second hydraulic cylinder in the first aspect of the invention.  
     [0030] The first hydraulic cylinder  32  includes a cylinder tube  36  and a piston  38 . The cylinder tube  36  has a bottomed cylindrical shape and opens toward the right side in FIG. 3. The cylinder tube  36  is provided so as to be non-rotatable with respect to the input shaft  22  and non-movable in the direction of the axis O (in the lateral direction in FIG. 3). The piston  38  is fitted in the cylinder tube  36  so as to be movable in the direction of the axis O.  
     [0031] When hydraulic fluid is supplied to a pressure chamber  40  between the cylinder tube  36  and the piston  38 , the piston  38  is moved in a first direction, that is, to the right side in FIG. 3 such that the first clutch C 1  is frictionally engaged. Sealing members  42 ,  44  made of rubber or the like are fixed to an inner peripheral portion and an outer peripheral portion of the piston  38  respectively so as to fluid-tightly seal the pressure chamber  40 .  
     [0032] Also, the first clutch C 1  includes a drum  46 , plural friction members  48 , and plural friction members  50 . The drum  46  is provided so as to be continuous to, and integral with an outer cylinder portion of the cylinder tube  36 . The plural friction members  48  are provided on the drum  46  so as to be non-rotatable with respect thereto. The plural friction members  50  are provided on the second rotation element RM 2  so as to be non-rotatable with respect thereto. Each of the friction members  48  and each of the friction members  50  are arranged alternately.  
     [0033] When the friction members  48 ,  50  are pressed so as to be frictionally engaged between the piston  38  and a pressing plate  54  which is positioned by a stopper  52  (a snap ring or the like) provided at an end portion of the drum  46 , the second rotation element RM 2  is integrally connected with the input shaft  22 .  
     [0034] A second hydraulic cylinder  34  is provided so as to be adjacent to the first hydraulic cylinder  32  in the first direction (on the right side in FIG. 3).  
     [0035] The second hydraulic cylinder  34  includes a cylinder tube  56  and a piston  58 . The cylinder tube  56  has bottomed cylindrical shape, and opens toward the right side in FIG. 3. The cylinder tube  56  is provided so as to be non-rotatable with respect to the input shaft  22  and non-movable in the direction of the axis O. The piston  58  is fitted in the cylinder tube  56  so as to be movable in the direction of the axis O. When hydraulic fluid is supplied to a pressure chamber  60  between the cylinder tube  56  and the piston  58 , the second hydraulic cylinder  34  moves the piston  58  in a second direction which is the same direction as the first direction, that is, to the right side in FIG. 3 such that the second clutch C 2  is frictionally engaged.  
     [0036] Sealing members  62 ,  64  made of rubber or the like are fixed to an inner peripheral portion and an outer peripheral portion of the piston  58  respectively so as to fluid-tightly seal the pressure chamber  60 .  
     [0037] Also, the second clutch C 2  includes a drum  66 , plural friction members  68 , and plural friction members  70 . The drum  66  is provided so as to be continuous to, and integral with an outer cylinder of the cylinder tube  56 . The plural friction members  68  are provided on the drum  66  so as to be non-rotatable with respect thereto. The plural friction members  70  are provided on the fourth rotation member RM 4  so as to be non-rotatable with respect thereto. Each of the friction members  68  and each of the friction members  70  are arranged alternately.  
     [0038] In the case of the second clutch C 2 , the friction members  68 ,  70  are pressed so as to be frictionally engaged between the piston  58  and a pressing plate  74  positioned by a stopper  72  (a snap ring or the like) provided at an end portion of the drum  66 . When the friction member  68 ,  70  are frictionally engaged in this manner, the fourth rotation element RM 4  is integrally connected with the input shaft  22 . The second clutch C 2  has a diameter smaller than that of the first clutch C 1 , and is provided so as to partly overlap the first clutch C 1  in the direction of the axis O.  
     [0039] The second hydraulic cylinder  34  also includes a cancel plate  80  which is provided integrally with the input shaft  22 . In the second hydraulic cylinder  34 , a centrifugal hydraulic pressure canceller chamber  82  is formed between the cancel plate  80  and the piston  58 . The centrifugal hydraulic pressure canceller chamber  82  is provided so as to be opposed to the pressure chamber  60  with the piston  58  therebetween. The centrifugal hydraulic pressure canceller chamber  82  cancels the centrifugal hydraulic pressure generated in the pressure chamber  60  due to the rotation around the axis O when the hydraulic fluid is introduced into the pressure chamber  60  from a fluid passage (not shown) provided in an inner peripheral portion of the input shaft  22  and the like. The piston  58  includes an outer cylinder  84  which has a cylindrical shape. A sealing member  86  made of rubber or the like is fixed to an outer peripheral edge of the cancel plate  80  so as to be slidably contact an inner peripheral surface of the outer cylinder portion  84 . The sealing member  86  fluid-tightly seals between an outer peripheral surface of the cancel plate  80  and the inner peripheral surface of the outer cylinder portion  84  while permitting the piston  58  to move. A return spring  88  is provided in the centrifugal hydraulic pressure canceller chamber  82 . When the hydraulic pressure in the pressure chamber  60  is reduced, the return spring  88  causes the piston  58  to retreat to the left side in FIG. 3 such that the second clutch C 2  is disengaged.  
     [0040] Also, in the first hydraulic cylinder  32 , a centrifugal hydraulic canceller chamber  90  is formed between the cylinder tube  56  of the second hydraulic cylinder  34  and the piston  38  using the cylinder tube  56  as a cancel plate. The centrifugal hydraulic canceller chamber  90  is opposed to the pressure chamber  40  with the piston  38  therebetween. The centrifugal hydraulic pressure canceller chamber  90  cancels the centrifugal hydraulic pressure generated in the pressure chamber  40  due to the rotation around the axis O when the hydraulic fluid is introduced into the pressure chamber  40  from a fluid passage (not shown) provided in an inner peripheral portion of the input shaft  22  and the like. The piston  38  includes an outer cylinder portion  92  which has a cylindrical shape and which is fitted to an outer peripheral side of the cylinder tube  56 . A sealing member  94  made of rubber or the like is fixed to the outer peripheral portion of the cylinder tube  56  so as to slidably contact an inner peripheral surface of the outer cylinder portion  92 . The sealing member  94  fluid-tightly seals between an outer peripheral surface of the cylinder tube  56  and the inner peripheral surface of the outer cylinder portion  92  while permitting the piston  38  to move. A return spring  96  is provided in the centrifugal hydraulic pressure canceller  90 . When the hydraulic pressure in the pressure chamber  40  is reduced, the return spring  96  causes the piston  38  to retreat to the left side in FIG. 3 such that the first clutch C 1  is disengaged. The outer cylinder portion  92  corresponds to a fitting portion.  
     [0041] The cylinder tube  36  and the piston  38  of the first hydraulic cylinder  32 , and the cylinder tube  56 , the piston  58 , and the cancel plate  80  of the second hydraulic cylinder  34  are all formed by performing drawing processing or the like on a metal plate using a press.  
     [0042] In the power transmission interruption apparatus  30  according to the embodiment, the cylinder tube  56  of the second hydraulic cylinder  34  is used as the cancel plate, and forms the centrifugal hydraulic canceller chamber  90  of the first hydraulic cylinder  34 . Thus, as compared with the case where the cancel plate is separately provided, the number of components decreases, which reduces the weight and manufacturing cost. In addition, a linear dimension in the direction of the axis O is shortened, which makes the configuration compact.  
     [0043] In the embodiment, the sealing member  94  is fixed to the cylinder tube  56  of the second hydraulic cylinder  34 . However, as shown in FIG. 4, a fitting portion  100  which is fitted to an outer peripheral side of the cylinder tube  56  may be provided on the piston  38  of the first hydraulic cylinder  32 , an annular groove may be formed in an inner peripheral surface of the fitting portion  100 , and an O-ring  102  may be fitted therein such that the O-ring  102  fluid-tightly seals between the fitting portion  100  and the outer peripheral surface of the cylinder tube  56 . The O-ring  102  corresponds to the sealing member.  
     [0044] In the power transmission interruption apparatus according to the embodiment, for example, each of the first hydraulic cylinder  32 , the second hydraulic cylinder  34 , and the first clutch C 1  and the second clutch C 2  as the friction engaging devices is configured to have an annular shape with the rotation member having a shaft shape at the center thereof. However, various configuration may be made, such as a configuration in which a hydraulic cylinder and a friction engaging device are provided inside a rotation member having a cylindrical shape, and a configuration in which the second hydraulic cylinder  34  includes a disc-shaped piston that does not have an opening portion at the center thereof.  
     [0045] Further, the pair of the friction engaging devices may have substantially the same diameter, and may be provided so as to be adjacent to each other in the axial direction. Alternatively, the pair of the friction engaging devices may be provided in substantially the same position in the axial direction such that one of the friction engaging devices is positioned on an inner peripheral side of the other.  
     [0046] It is preferable that the centrifugal hydraulic pressure canceller chamber should be provided in the second hydraulic cylinder  34 . However, the centrifugal hydraulic canceller chamber in the second hydraulic cylinder  34  is not necessarily essential for realizing the invention.  
     [0047] It is preferable to use, as the friction engaging device, a multi plate type clutch and a multi plate type brake in which two or more friction members are provided on each of two members that are rotatable with respect to each other. However, a single plate type friction engaging device in which one friction member is provided on each member may be employed.  
     [0048] Power may be transmitted from the rotation member (the input shaft  22 ) to the first connecting member (the second rotation element RM 2 ), and the second connecting member (the fourth rotation element RM 4 ), or may be transmitted reversely. Alternatively, the direction in which power is transmitted may be switched according to a condition. The first connecting member (the second rotation element RM 2 ) and the second connecting member (the fourth rotation element RM 4 ) may rotate around the axis, or may be fixed to a housing or the like so as to be non-rotatable around the axis. Also, the first connecting member (the second rotation element RM 2 ) and the second connecting member (the fourth rotation element RM 4 ) may be separate from each other so as to be rotatable with respect to each other, or may be integrally connected to each other so as to rotate together.  
     [0049] The direction in which the piston  58  of the second hydraulic cylinder  34  is moved may be the same as the first direction, that is, the direction in which the piston  38  of the first hydraulic cylinder  32  is moved, or may be a direction opposite to the first direction.  
     [0050] According to an embodiment shown in FIG. 4, the piston  38  of the first hydraulic cylinder  32  is fitted to the outer peripheral side of the cylinder tube  56  of the second hydraulic cylinder  34 . However, when the invention is realized in another embodiment, for example, the configuration may be such that the second hydraulic cylinder having an annular shape is provided inside a rotation member having a cylindrical shape, and the piston of the first hydraulic cylinder is fitted to the inner peripheral side of an inner cylinder of a cylinder tube having an annular shape.  
     [0051] According to the embodiment shown in FIG. 4, the fitting portion is provided on the piston  38  of the first hydraulic cylinder  32  so as to be fitted to the cylinder tube  56  of the second hydraulic cylinder  34 . However, in the case where the piston of the first hydraulic cylinder protrudes in the direction opposite to the first direction, the cylinder tube of the first hydraulic cylinder and the cylinder tube of the second hydraulic cylinder may be integrally connected so as to form a centrifugal hydraulic pressure canceller chamber.  
     [0052] While the embodiments of the invention have been described in detail with reference to the accompanying drawings, the embodiments are only examples, and the invention can be realized in embodiments in which various changes and improvements are made based on the knowledge of those skilled in the art.