Abstract:
A transmission of the present invention has an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices include clutches and brakes. A method for controlling the transmission selectively engages the torque transmitting devices in combinations of at least two to establish at least nine forward speed ratios and at least one reverse speed ratio.

Description:
FIELD 
       [0001]    The invention relates generally to a multiple speed transmission having a plurality of planetary gear sets and a plurality of torque transmitting devices, and more particularly to a method for controlling transmission having nine or more speeds, four planetary gear sets and a plurality of torque transmitting devices. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0003]    A typical multiple speed transmission uses a combination of friction clutches or brakes, planetary gear arrangements and fixed interconnections to achieve a plurality of gear ratios. The number and physical arrangement of the planetary gear sets, generally, are dictated by packaging, cost and desired speed ratios. 
         [0004]    While current transmissions achieve their intended purpose, the need for new and improved transmission configurations which exhibit improved performance, especially from the standpoints of efficiency, responsiveness and smoothness and improved packaging, primarily reduced size and weight, is essentially constant. Accordingly, there is a need for an improved, cost-effective, compact multiple speed transmission. 
       SUMMARY 
       [0005]    A transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling or interconnecting members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices are for example clutches and brakes. 
         [0006]    In another embodiment of the present invention, a method for controlling a transmission is provided. The method includes providing an input member, providing an output member, providing a first, second, third and fourth planetary gear sets each having first, second and third members, providing a first interconnecting member for continuously interconnecting the third member of the first planetary gear set with first members of the third and fourth planetary gear sets, providing a second interconnecting member for continuously interconnecting the second member of the first planetary gear set with the third member of the second planetary gear set, providing a third interconnecting member for continuously interconnecting the first member of the second planetary gear set and the input member with the second member of the fourth planetary gear set, providing a first torque transmitting device to selectively interconnect the input member, the first member of the second planetary gear set and second member of the fourth planetary gear set with the second member of the second planetary gear set, providing a second torque transmitting device to selectively interconnect the second member of the second planetary gear set with the third member of the first planetary gear set and the first members of the third and fourth planetary gear sets, providing a third torque transmitting device to selectively to interconnect the second member of the third planetary gear set and the output member with the third member of the fourth planetary gear set, providing a fourth torque transmitting device to selectively to interconnect the second member of the second planetary gear set with the stationary member, providing a fifth torque transmitting device to selectively interconnect the first member of the first planetary gear set with the stationary member, and providing a sixth torque transmitting device to selectively interconnect the third member of the third planetary gear set with the stationary member. 
         [0007]    In yet another embodiment of the present invention, the method further includes establishing a first forward speed ratio by selectively activating the second, the fifth and the sixth torque transmitting devices. 
         [0008]    In yet another embodiment of the present invention, the method further includes establishing a second forward speed ratio by selectively activating the first, the second and the sixth torque transmitting devices. 
         [0009]    In yet another embodiment of the present invention, the method further includes establishing a third forward speed ratio by selectively activating the first, the fifth and the sixth torque transmitting devices. 
         [0010]    In still another embodiment of the present invention, the method further includes establishing a fourth forward speed ratio by selectively activating the third and the sixth torque transmitting devices and at least one of the first, second, the fourth and the fifth torque transmitting devices. 
         [0011]    In still another embodiment of the present invention, the method further includes establishing a fifth forward speed ratio by selectively activating the first, the third and the fifth torque transmitting devices. 
         [0012]    In still another embodiment of the present invention, the method further includes establishing a sixth forward speed ratio by selectively activating the first, the second and the third torque transmitting devices. 
         [0013]    In still another embodiment of the present invention, the method further includes establishing a seventh forward speed ratio by selectively activating the second, the third and the fifth torque transmitting devices. 
         [0014]    In still another embodiment of the present invention, the method further includes establishing an eighth forward speed ratio by selectively activating the second, the third and the fourth torque transmitting devices. 
         [0015]    In still another embodiment of the present invention, the method further includes establishing a ninth forward speed ratio by selectively activating the third, the fourth and the fifth torque transmitting devices. 
         [0016]    In still another embodiment of the present invention, the method further includes establishing a reverse speed ratio by selectively activating the fourth, the fifth and the sixth torque transmitting devices. 
         [0017]    In still another embodiment of the present invention, the method further includes establishing a fourth forward speed ratio by selectively activating at least the third and the sixth torque transmitting devices. 
         [0018]    In still another embodiment of the present invention, the method further includes establishing a fourth forward speed ratio by selectively activating the third, the fifth and the sixth torque transmitting device. 
         [0019]    In still another embodiment of the present invention, the method further includes establishing a fourth forward speed ratio by selectively activating the first, the third and the sixth torque transmitting device. 
         [0020]    In still another embodiment of the present invention, the method further includes establishing a fourth forward speed ratio by selectively activating the third, the fourth and the sixth torque transmitting device. 
         [0021]    In still another embodiment of the present invention, the method further includes establishing a fourth forward speed ratio by selectively activating the second, the third and the sixth torque transmitting device. 
         [0022]    Further aspects and advantages of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature. 
     
    
     
       DRAWINGS 
         [0023]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0024]      FIG. 1  is a diagrammatic view of an embodiment of a nine speed transmission according to the present invention; and 
           [0025]      FIG. 2  is a truth table presenting the state of engagement of the various torque transmitting elements in each of the available forward and reverse speeds or gear ratios of the transmission illustrated in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0027]    Referring now to  FIG. 1 , a stick diagram presents a schematic layout of the embodiment of the nine speed transmission  10  according to the present invention. The transmission  10  includes an input shaft or member  12 , a first planetary gear set  14 , a second planetary gear set  16 , a third planetary gear set  18  and a fourth planetary gear set  20  and an output shaft or member  22 . 
         [0028]    The planetary gear set  14  includes a sun gear member  14 A, a ring gear member  14 C and a planet gear carrier member  14 B that rotatably supports a set of planet gears  14 D (only one of which is shown). The sun gear member  14 A is connected for common rotation with a first shaft or interconnecting member  42 . The ring gear member  14 C is connected for common rotation with a second shaft or interconnecting member  44 . The planet carrier member  14 B is also connected for common rotation with the third shaft or interconnecting member  45 . The planet gears  14 D are each configured to intermesh with both the sun gear member  14 A and the ring gear member  14 C. 
         [0029]    The planetary gear set  16  includes a sun gear member  16 A, a ring gear member  16 C and a planet gear carrier member  16 B that rotatably supports a set of planet gears  16 D (only one of which is shown). The sun gear member  16 A is connected for common rotation with the input member  12 . The ring gear member  16 C is connected for common rotation with the third shaft or interconnecting member  45 . The planet carrier member  16 B is connected for common rotation with a fourth shaft or interconnecting member  46  and with a fifth shaft or interconnecting member  48 . The planet gears  16 D are each configured to intermesh with both the sun gear member  16 A and the ring gear member  16 C. 
         [0030]    The planetary gear set  18  includes a sun gear member  18 A, a ring gear member  18 C and a planet gear carrier member  18 B that rotatably supports a set of planet gears  18 D (only one of which is shown). The sun gear member  18 A is connected for common rotation with the second shaft or interconnecting member  44  and a sixth shaft or interconnecting member  52 . The ring gear member  18 C is connected for common rotation with a seventh shaft or interconnecting member  54 . The planet carrier member  18 B is connected for common rotation with the output shaft  22 . The planet gears  18 D are each configured to intermesh with both the sun gear member  18 A and the ring gear member  18 C. 
         [0031]    The planetary gear set  20  includes a sun gear member  20 A, a ring gear member  20 B and a planet gear carrier member  20 C that rotatably supports a set of planet gears  20 D (only one of which is shown). The sun gear member  20 A is connected for common rotation with the sixth shaft or interconnecting member  52 . The ring gear member  20 C is connected for common rotation with an eighth shaft or interconnecting member  56 . The planet carrier member  20 B is connected for common rotation with the input shaft  12 . The set of planet gears  20 D are each configured to intermesh with both the sun gear member  20 A and the ring gear member  20 C. 
         [0032]    The input shaft or member  12  is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member  22  is continuously connected with the final drive unit or transfer case (not shown). 
         [0033]    The torque-transmitting mechanisms or the clutches  26 ,  28 ,  30  and the brakes  32 ,  34  and  36  allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch  26  is selectively engageable to connect the input shaft or member  12  with the fourth shaft or interconnecting member  46 . The second clutch  28  is selectively engageable to connect the second shaft or interconnecting member  44  with the fifth shaft or interconnecting member  48 . The third clutch  30  is selectively engageable to connect the eighth shaft or interconnecting member  56  with the output shaft or member  22 . The first brake  32  is selectively engageable to connect the fourth shaft or interconnecting member  46  with the stationary element or the transmission housing  50  in order to prevent the fourth shaft or interconnecting member  46  from rotating relative to the transmission housing  50 . The second brake  34  is selectively engageable to connect the first shaft or interconnecting member  42  with a stationary element or the transmission housing  50  in order to prevent the first shaft or interconnecting member  42  from rotating relative to the transmission housing  50 . The third brake  36  is selectively engageable to connect the seventh shaft or interconnecting member  54  with a stationary element or the transmission housing  50  in order to prevent the seventh shaft or interconnecting member  54  from rotating relative to the transmission housing  50 . 
         [0034]    Referring now to  FIGS. 1 and 2 , the operation of or method for controlling the embodiment of the nine speed transmission  10  will be described. It will be appreciated that the transmission  10  is capable of transmitting torque from the input shaft or member  12  to the output shaft or member  22  in at least nine forward speed or torque ratios and at least one reverse speed or torque ratio with a triple overdrive. Each forward and reverse speed or torque ratio is attained by engagement of one or more of the torque-transmitting mechanisms (i.e. first clutch  26 , second clutch  28 , third clutch  30 , first brake  32 , second brake  34  and third brake  36 ), as will be explained below.  FIG. 2  is a truth table presenting the various combinations of torque-transmitting elements that are activated or engaged to achieve the various gear states. Actual numerical gear ratios of the various gear states are also presented although it should be appreciated that these numerical values are exemplary only and that they may be adjusted over significant ranges to accommodate various applications and operational criteria of the transmission  10 . An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown in  FIG. 2 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
         [0035]    To establish reverse gear, the first brake  32 , the second brake  34  and the third brake  36  are engaged or activated. The first brake  32  connects the fourth shaft or interconnecting member  46  with a stationary element or the transmission housing  50  in order to prevent the fourth shaft or interconnecting member  46  from rotating relative to the transmission housing  50 . The second brake  34  connects the first shaft or interconnecting member  42  with a stationary element or the transmission housing  50  in order to prevent the first shaft or interconnecting member  42  from rotating relative to the transmission housing  50 . The third brake  36  connects the seventh shaft or interconnecting member  54  with a stationary element or the transmission housing  50  in order to prevent the seventh shaft or interconnecting member  54  from rotating relative to the transmission housing  50 . 
         [0036]    To establish a first gear ratio, the second clutch  28 , the second brake  34  and the third brake  36  are engaged or activated. The second clutch  28  connects the second shaft or interconnecting member  44  with the fifth shaft or interconnecting member  48 . The second brake  34  connects the first shaft or interconnecting member  42  with a stationary element or the transmission housing  50  in order to prevent the first shaft or interconnecting member  42  from rotating relative to the transmission housing  50 . The third brake  36  connects the seventh shaft or interconnecting member  54  with a stationary element or the transmission housing  50  in order to prevent the seventh shaft or interconnecting member  54  from rotating relative to the transmission housing  50 . 
         [0037]    To establish a second gear ratio, the first clutch  26 , the second clutch  28  and the third brake  36  are engaged or activated. The first clutch  26  connects the input shaft or member  12  with the fourth shaft or interconnecting member  46 . The second clutch  28  connects the second shaft or interconnecting member  44  with the fifth shaft or interconnecting member  48 . The third brake  36  connects the seventh shaft or interconnecting member  54  with a stationary element or the transmission housing  50  in order to prevent the seventh shaft or interconnecting member  54  from rotating relative to the transmission housing  50 . 
         [0038]    To establish a third gear ratio, the first clutch  26 , the second brake  34  and the third brake  36  are engaged or activated. The first clutch  26  connects the input shaft or member  12  with the fourth shaft or interconnecting member  46 . The second brake  34  connects the first shaft or interconnecting member  42  with a stationary element or the transmission housing  50  in order to prevent the first shaft or interconnecting member  42  from rotating relative to the transmission housing  50 . The third brake  36  connects the seventh shaft or interconnecting member  54  with a stationary element or the transmission housing  50  in order to prevent the seventh shaft or interconnecting member  54  from rotating relative to the transmission housing  50 . 
         [0039]    To establish a fourth gear ratio, the third clutch  30  and the third brake  36  are engaged or activated. The third clutch  30  connects the eighth shaft or interconnecting member  56  with the output shaft or member  22 . The third brake  36  connects the seventh shaft or interconnecting member  54  with a stationary element or the transmission housing  50  in order to prevent the seventh shaft or interconnecting member  54  from rotating relative to the transmission housing  50 . Moreover, the second brake  34  may be engaged or activated but will be carrying zero torque. The engagement of second brake  34  is not required to establish the fourth gear or speed ratio. The second brake  34  connects the first shaft or interconnecting member  42  with a stationary element or the transmission housing  50  in order to prevent the first shaft or interconnecting member  42  from rotating relative to the transmission housing  50 . 
         [0040]    To establish an alternative fourth gear ratio, the third clutch  30  and the third brake  36  are engaged or activated. The third clutch  30  connects the eighth shaft or interconnecting member  56  with the output shaft or member  22 . The third brake  36  connects the seventh shaft or interconnecting member  54  with a stationary element or the transmission housing  50  in order to prevent the seventh shaft or interconnecting member  54  from rotating relative to the transmission housing  50 . Moreover, the first clutch  26  may be engaged or activated but will be carrying zero torque. The engagement of the first clutch  26  is not required to establish the fourth gear or speed ratio. The first clutch  26  connects the input shaft or member  12  with the fourth shaft or interconnecting member  46 . 
         [0041]    To establish yet another alternative fourth gear ratio, the third clutch  30  and the third brake  36  are engaged or activated. The third clutch  30  connects the eighth shaft or interconnecting member  56  with the output shaft or member  22 . The third brake  36  connects the seventh shaft or interconnecting member  54  with a stationary element or the transmission housing  50  in order to prevent the seventh shaft or interconnecting member  54  from rotating relative to the transmission housing  50 . Moreover, the first brake  32  may be engaged or activated but will be carrying zero torque. The engagement of the first brake  32  is not required to establish the fourth gear or speed ratio. The first brake  32  connects the fourth shaft or interconnecting member  46  with the stationary element or the transmission housing  50  in order to prevent the fourth shaft or interconnecting member  46  from rotating relative to the transmission housing  50 . 
         [0042]    To establish yet another alternative fourth gear ratio, the third clutch  30  and the third brake  36  are engaged or activated. The third clutch  30  connects the eighth shaft or interconnecting member  56  with the output shaft or member  22 . The third brake  36  connects the seventh shaft or interconnecting member  54  with a stationary element or the transmission housing  50  in order to prevent the seventh shaft or interconnecting member  54  from rotating relative to the transmission housing  50 . Moreover, the second clutch  28  may be engaged or activated but will be carrying zero torque. The engagement of the second clutch  28  is not required to establish the fourth gear or speed ratio. The second clutch  28  connects the second shaft or interconnecting member  44  with the fifth shaft or interconnecting member  48 . 
         [0043]    To establish a fifth gear ratio, the first clutch  26 , the third clutch  30  and the second brake  34  are engaged or activated. The first clutch  26  connects the input shaft or member  12  with the fourth shaft or interconnecting member  46 . The third clutch  30  connects the eighth shaft or interconnecting member  56  with the output shaft or member  22 . The second brake  34  connects the first shaft or interconnecting member  42  with a stationary element or the transmission housing  50  in order to prevent the first shaft or interconnecting member  42  from rotating relative to the transmission housing  50 . 
         [0044]    To establish a sixth gear ratio, the first clutch  26 , the second clutch  28  and the third clutch  30  are engaged or activated. The first clutch  26  connects the input shaft or member  12  with the fourth shaft or interconnecting member  46 . The second clutch  28  connects the second shaft or interconnecting member  44  with the fifth shaft or interconnecting member  48 . The third clutch  30  connects the eighth shaft or interconnecting member  56  with the output shaft or member  22 . 
         [0045]    To establish a seventh gear ratio, the second clutch  28 , the third clutch  30  and the second brake  34  are engaged or activated. The second clutch  28  connects the second shaft or interconnecting member  44  with a fifth shaft or interconnecting member  48 . The third clutch  30  connects the eighth shaft or interconnecting member  56  with the output shaft or member  22 . The second brake  34  connects the first shaft or interconnecting member  42  with a stationary element or the transmission housing  50  in order to prevent the first shaft or interconnecting member  42  from rotating relative to the transmission housing  50 . 
         [0046]    To establish an eighth gear ratio, the second clutch  28 , the third clutch  30  and the first brake  32  are engaged or activated. The second clutch  28  connects the second shaft or interconnecting member  44  with the fifth shaft or interconnecting member  48 . The third clutch  30  connects the eighth shaft or interconnecting member  56  with the output shaft or member  22 . The first brake  32  connects the fourth shaft or interconnecting member  46  with the stationary element or the transmission housing  50  in order to prevent the fourth shaft or interconnecting member  46  from rotating relative to the transmission housing  50 . 
         [0047]    To establish a ninth gear ratio, the third clutch  30 , the first brake  32  and the second brake  34  are engaged or activated. The third clutch  30  connects the eighth shaft or interconnecting member  56  with the output shaft or member  22 . The first brake  32  connects the fourth shaft or interconnecting member  46  with the stationary element or the transmission housing  50  in order to prevent the fourth shaft or interconnecting member  46  from rotating relative to the transmission housing  50 . The second brake  34  connects the first shaft or interconnecting member  42  with a stationary element or the transmission housing  50  in order to prevent the first shaft or interconnecting member  42  from rotating relative to the transmission housing  50 . 
         [0048]    It will be appreciated that the foregoing explanation of operation and gear states of the nine speed transmission  10  assumes, first of all, that all the clutches and brakes not specifically referenced in a given gear state are inactive or disengaged and, second of all, that during gear shifts, i.e., changes of gear state, between at least adjacent gear states, a clutch or brake engaged or activated in both gear states will remain engaged or activated. 
         [0049]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.