Abstract:
A transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling members and six torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices may include clutches and brakes.

Description:
CROSS-REFERENCE 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/430,504, filed Jan. 6, 2011. The entire contents of the above application are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    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 multiple speed transmission having four planetary gear sets and a plurality of torque transmitting devices. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0004]    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. 
         [0005]    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 
       [0006]    A transmission is provided having 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 are for example clutches and brakes. 
         [0007]    In one example, the transmission includes an input member, an output member, a first and a second planetary gear set each having a first, a second, and a third member, wherein each of the first, second, and third members is included in one of a first rotary member, a second rotary member, a third rotary member, and a fourth rotary member, and wherein two of the members of the first planetary gear set are directly separately connected with two of the members of the second planetary gear set to form the first and the second rotary members and wherein the fourth rotary member is directly connected to the input member. 
         [0008]    The transmission also includes a third and a fourth planetary gear set each having a first, a second, and a third member, wherein each of the first, second, and third members is included in one of a fifth rotary member, a sixth rotary member, a seventh rotary member, and an eighth rotary member, and wherein two of the members of the third planetary gear set are directly separately connected with two of the members of the fourth planetary gear set to form the fifth and sixth rotary members and wherein the sixth rotary member is directly connected to the output member. An interconnecting member continuously connected to the first rotary member and the seventh rotary member. 
         [0009]    Six torque transmitting devices are each selectively engageable to connect at least one of the first, second, third, fourth, fifth, seventh, and eighth rotary members with at least one other of a stationary member and the first, second, third, fourth, fifth, seventh, and eighth rotary members. The torque transmitting devices are selectively engageable in combinations of at least two to establish multiple forward speed ratios and at least one reverse speed ratio between the input member and the output member. 
         [0010]    Further features, 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 
         [0011]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0012]      FIG. 1  is a lever diagram of an embodiment of a multiple speed transmission according to the present invention; 
           [0013]      FIG. 2  is a diagrammatic view of an embodiment of a multiple speed transmission according to the present invention; and 
           [0014]      FIG. 3  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  FIGS. 1 and 2 ; 
           [0015]      FIG. 4  is a diagrammatic view of an embodiment of a multiple speed transmission according to the present invention; 
           [0016]      FIG. 5  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  FIGS. 1 and 4 ; 
           [0017]      FIG. 6  is a diagrammatic view of an embodiment of a multiple speed transmission according to the present invention; 
           [0018]      FIG. 7  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  FIGS. 1 and 6 ; 
           [0019]      FIG. 8  is a diagrammatic view of an embodiment of a multiple speed transmission according to the present invention; 
           [0020]      FIG. 9  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  FIGS. 1 and 8 ; 
           [0021]      FIG. 10  is a diagrammatic view of an embodiment of a multiple speed transmission according to the present invention; and 
           [0022]      FIG. 11  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  FIGS. 1 and 10 . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0024]    Referring now to  FIG. 1 , an embodiment of a multiple speed transmission  10  is illustrated in a lever diagram format. A lever diagram is a schematic representation of the components of a mechanical device such as an automatic transmission. Each individual lever represents a planetary gear set wherein the three basic mechanical components of the planetary gear set are each represented by a node. Therefore, a single lever contains three nodes: one for the sun gear, one for the planet gear carrier, and one for the ring gear. The relative length between the nodes of each lever can be used to represent the ring-to-sun ratio of each respective gear set. These lever ratios, in turn, are used to vary the gear ratios of the transmission in order to achieve appropriate ratios and ratio progression. Mechanical couplings or interconnections between the nodes of the various planetary gear sets are illustrated by thin, horizontal lines and torque transmitting devices such as clutches and brakes are presented as interleaved fingers. If the device is a brake, one set of the fingers is grounded. Further explanation of the format, purpose and use of lever diagrams can be found in SAE Paper 810102, “The Lever Analogy: A New Tool in Transmission Analysis” by Benford and Leising which is hereby fully incorporated by reference. 
         [0025]    The transmission  10  includes an input shaft or member  12 , a first planetary gear set  14  having three nodes: a first node  14 A, a second node  14 B and a third node  14 C, a second planetary gear set  16  having three nodes: a first node  16 A, a second node  16 B and a third node  16 C, a third planetary gear set  18  having three nodes: a first node  18 A, a second node  18 B and a third node  18 C, a fourth planetary gear set  20  having three nodes: a first node  20 A, a second node  20 B and a third node  20 C and an output shaft or member  22 . 
         [0026]    The input member  12  is coupled to the first node  16 A of the second planetary gear set  16 . The output member  22  is coupled to the second node  18 B of the third planetary gear set  18  and the second node  20 B of the fourth planetary gear set  20 . The second node  14 B of the first planetary gear set  14  is coupled to the second node  16 B of the second planetary gear set  16 . The third node  14 C of the first planetary gear set  14  is coupled to the third node  16 C of the second planetary gear set  16  and the first node  18 A of the third planetary gear set  18 . The second node  18 B of the third planetary gear set  18  is coupled to the second node  20 B of the fourth planetary gear set  20 . The third node  18 C of the third planetary gear set  18  is coupled to the third node  20 C of the fourth planetary gear set  20 . 
         [0027]    A first clutch  26  selectively connects the first node  16 A of the second planetary gear set  16  and the input member  12  with the third node  18 C of the third planetary gear set  18  and the third node  20 C of the fourth planetary gear set  20 . A second clutch  28  selectively connects the first node  16 A of the second planetary gear set  16  and the input member  12  with the first node  20 A of the fourth planetary gear set  20 . A first brake  30  selectively connects the first node  14 A of the first planetary gear set  14  to a stationary member or a transmission housing  40 . A second brake  32  selectively connects the second node  14 B of the first planetary gear set  14  and the second node  16 B of the second planetary gear set  16  to a stationary member or transmission housing  40 . A third brake  34  selectively connects the third node  14 C of the first planetary gear set, the third node  16 C of the second planetary gear set  16 , and the first node  18 A of the third planetary gear set  18  to the stationary member or transmission housing  40 . A fourth brake  36  selectively connects the third node  18 C of the third planetary gear set  18  and the third node  20 C of the fourth planetary gear set  20  to the stationary member or transmission housing  40 . 
         [0028]    Referring now to  FIG. 2 , a stick diagram presents a schematic layout of the embodiment of the multiple speed transmission  10  according to the present invention. In  FIG. 2 , the numbering from the lever diagram of  FIG. 1  is carried over. The clutches, brakes, and couplings are correspondingly presented whereas the nodes of the planetary gear sets now appear as components of planetary gear sets such as sun gears, ring gears, planet gears and planet gear carriers. 
         [0029]    For example, the first planetary gear set  14  includes a sun gear member  14 A, a planet gear carrier member  14 C and a ring gear member  14 B. The sun gear member  14 A is connected for common rotation with a first shaft or interconnecting member  42 . The ring gear member  14 B is connected for common rotation with a second shaft or interconnecting member  44 . The planet gear carrier member  14 C rotatably supports a set of planet gears  14 D (only one of which is shown) and is connected for common rotation with a third shaft or interconnecting member  46  and a fourth shaft or interconnecting member  48 . The planet gears  14 D are each configured to intermesh with both the sun gear member  14 A and the ring gear member  14 B. 
         [0030]    The second planetary gear set  16  includes a sun gear member  16 A, a planet carrier member  16 C that rotatably supports a set of planet gears  16 D and  16 E, and a ring gear member  16 B. The sun gear member  16 A is connected for common rotation with the input member  12 . The ring gear member  16 B is connected for common rotation with the second shaft or interconnecting member  44 . The planet carrier member  16 C is connected for common rotation with the fourth shaft or interconnecting member  48  and a fifth shaft or interconnecting member  50 . The planet gears  16 D are each configured to intermesh with both the ring gear member  16 B and the planet gears  16 E. The planet gears  16 E are each configured to intermesh with both the planet gears  16 D and the sun gear  16 A. 
         [0031]    The third planetary gear set  18  includes a sun gear member  18 A, a ring gear member  18 B and a planet carrier member  18 C that rotatably supports a set of planet gears  18 D. The sun gear member  18 A is connected for common rotation with the fifth interconnecting member  50 . The ring gear member  18 B is connected for common rotation with a sixth shaft or interconnecting member  52 . The planet carrier member  18 C is connected for common rotation with a seventh shaft or interconnecting member  54  and with an eighth shaft or interconnecting member  56 . The planet gears  18 D are each configured to intermesh with both the sun gear member  18 A and the ring gear member  18 B. 
         [0032]    The fourth planetary gear set  20  includes a sun gear member  20 A, a ring gear member  20 C and a planet carrier member  20 B that rotatably supports a set of planet gears  20 D. The sun gear member  20 A is connected for common rotation with a ninth shaft or interconnecting member  58 . The ring gear member  20 C is connected for common rotation with the seventh interconnecting member  54 . The planet carrier member  20 B is connected for common rotation with the sixth interconnecting member  52  and with the output member  22 . The planet gears  20 D are each configured to intermesh with both the sun gear member  20 A and the ring gear member  20 C. 
         [0033]    The input shaft or member  12  is preferably continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft or member  22  is preferably continuously connected with the final drive unit or transfer case (not shown). 
         [0034]    The torque-transmitting mechanisms or clutches  26 ,  28  and brakes  30 ,  32 ,  34 ,  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 eighth interconnecting member  56  with the input member  12 . The second clutch  28  is selectively engageable to connect the ninth interconnecting member  58  with the input member  12 . The first brake  30  is selectively engageable to connect the first interconnecting member  42  to the stationary member or transmission housing  40  in order to restrict the sun gear member  14 A of the first planetary gear set  14  from rotating relative to the stationary member or transmission housing  40 . The second brake  32  is selectively engageable to connect the second interconnecting member  44  to the stationary member or transmission housing  40  in order to restrict the ring gear member  14 B of the first planetary gear set  14  and the ring gear member  16 B of the second planetary gear set  16  from rotating relative to the stationary member or transmission housing  40 . The third brake  34  is selectively engageable to connect the third interconnecting member  46  to the stationary member or transmission housing  40  in order to restrict the planet carrier member  14 C of the first planetary gear set  14 , the planet carrier member  16 C of the second planetary gear set  16 , and the sun gear  18 A of the third planetary gear set  18  from rotating relative to the stationary member or transmission housing  40 . The fourth brake  36  is selectively engageable to connect the seventh interconnecting member  54  to the stationary member or transmission housing  40  in order to restrict the planet carrier member  18 C of the third planetary gear set  18  and the ring gear member  20 C of the fourth planetary gear set  20  from rotating relative to the stationary element or transmission housing  40 . 
         [0035]    Referring now to  FIGS. 2 and 3 , the operation of the embodiment of the multiple 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. 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 , first brake  30 , second brake  32 , third brake  34 , and fourth brake  36 ), as will be explained below.  FIG. 3  is a truth table presenting the various combinations of torque transmitting mechanisms 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. 3 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
         [0036]    To establish reverse gear, the first brake  30  and the fourth brake  36  are engaged or activated. The first brake  30  connects the first interconnecting member  42  to the stationary member or transmission housing  40  in order to restrict the sun gear member  14 A of the first planetary gear set  14  from rotating relative to the stationary member or transmission housing  40 . The fourth brake  36  connects the seventh interconnecting member  54  to the stationary member or transmission housing  40  in order to restrict the planet carrier member  18 C of the third planetary gear set  18  and the ring gear member  20 C of the fourth planetary gear set  20  from rotating relative to the stationary element or transmission housing  40 . Likewise, the nine forward ratios are achieved through different combinations of clutch and brake engagement, as shown in  FIG. 3 . 
         [0037]    Turning to  FIG. 4 , a stick diagram presents a schematic layout of another embodiment of a multiple speed transmission  100  based on the transmission  10  according to the present invention. In  FIG. 4 , the components of planetary gear sets such as sun gears, ring gears, planet gears and planet gear carriers, clutches, brakes, and couplings are correspondingly presented in the transmission  100 . Referring now to  FIGS. 4 and 5 , the operation of the embodiment of the multiple speed transmission  100  will be described. It will be appreciated that the transmission  100  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. 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 , first brake  30 , second brake  32 , third brake  34 , and fourth brake  36 ).  FIG. 5  is a truth table presenting the various combinations of torque transmitting mechanisms 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  100 . An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown in  FIG. 5 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
         [0038]    Turning to  FIG. 6 , a stick diagram presents a schematic layout of another embodiment of a multiple speed transmission  200  based on the transmission  10  according to the present invention. In  FIG. 6 , the components of planetary gear sets such as sun gears, ring gears, planet gears and planet gear carriers, clutches, brakes, and couplings are correspondingly presented in the transmission  200 . Referring now to  FIGS. 6 and 7 , the operation of the embodiment of the multiple speed transmission  200  will be described. It will be appreciated that the transmission  200  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. 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 , first brake  30 , second brake  32 , third brake  34 , and fourth brake  36 ).  FIG. 7  is a truth table presenting the various combinations of torque transmitting mechanisms 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  200 . An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown in  FIG. 7 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
         [0039]    Turning to  FIG. 8 , a stick diagram presents a schematic layout of another embodiment of a multiple speed transmission  300  based on the transmission  10  according to the present invention. In  FIG. 8 , the components of planetary gear sets such as sun gears, ring gears, planet gears and planet gear carriers, clutches, brakes, and couplings are correspondingly presented in the transmission  300 . In transmission  300 , planetary gear sets  18  and  20  (shown in the lever diagram of  FIG. 1 ) are combined to form a planetary gear set assembly  17 . Planetary gear set assembly  17  includes sun gear members  18 A and  20 A, a ring gear member  18 B/ 20 B and a planet gear carrier member  18 C/ 20 C that rotatably supports a first set of planet gears  19  (only one of which is shown) and a second set of planet gears  21  (only one of which is shown). The planet gears  19  are long pinion gears that have a first end  19   a  and a second end  19   b . The planet gears  19  are each configured to intermesh with both the sun gear member  18 A at the first end  19   a  and intermesh with the ring gear member  18 B/ 20 B and the second set of planet gears  21  at the second end  19   b . The second set of planet gears  21  are each configured to intermesh with both the sun gear member  20 A and the first set of planet gears  19 . The sun gear member  18 A is interconnected with the ring gear  16 C of the second planetary gear set  16 . The ring gear member  18 B/ 20 B is connected for common rotation with the output shaft  22 . The planet carrier member  18 C/ 20 C is connected for common rotation with the brake  36  and clutch  26 . Sun gear member  20 A is connected for common rotation with clutch  28 . 
         [0040]    Referring now to  FIGS. 8 and 9 , the operation of the embodiment of the multiple speed transmission  300  will be described. It will be appreciated that the transmission  300  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. 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 , first brake  30 , second brake  32 , third brake  34 , and fourth brake  36 ).  FIG. 9  is a truth table presenting the various combinations of torque transmitting mechanisms 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  300 . An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown in  FIG. 9 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
         [0041]    Turning to  FIG. 10 , a stick diagram presents a schematic layout of another embodiment of a multiple speed transmission  400  based on the transmission  10  according to the present invention. In  FIG. 10 , the components of planetary gear sets such as sun gears, ring gears, planet gears and planet gear carriers, clutches, brakes, and couplings are correspondingly presented in the transmission  400 . In transmission  400 , planetary gear sets  14  and  16  (shown in the lever diagram of  FIG. 1 ) are combined to form a planetary gear set assembly  27 . Planetary gear set assembly  27  includes sun gear members  14 A and  16 A, a ring gear member  14 B/ 16 B and a planet gear carrier member  14 C/ 16 C that rotatably supports a first set of planet gears  29  (only one of which is shown) and a second set of planet gears  31  (only one of which is shown). The planet gears  29  are long pinion gears that have a first end  29   a  and a second end  29   b . The planet gears  29  are each configured to intermesh with both the sun gear member  14 A at the first end  29   a  and intermesh with the ring gear member  14 B/ 16 B and the second set of planet gears  31  at the second end  29   b . The second set of planet gears  31  are each configured to intermesh with both the sun gear member  16 A and the first set of planet gears  29 . The sun gear member  14 A is interconnected with brake  30 . The ring gear member  14 B/ 16 B is interconnected with brake  32 . The planet carrier member  14 C/ 16 C is connected with the brake  34  and the sun gear  18 A of the third planetary gear set  18 . Sun gear member  16 A is connected for common rotation with clutches  26  and  28  and input shaft  12 . 
         [0042]    Referring now to  FIGS. 10 and 11 , the operation of the embodiment of the multiple speed transmission  400  will be described. It will be appreciated that the transmission  400  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. 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 , first brake  30 , second brake  32 , third brake  34 , and fourth brake  36 ).  FIG. 11  is a truth table presenting the various combinations of torque transmitting mechanisms 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  400 . An example of the gear ratios that may be obtained using the embodiments of the present invention are also shown in  FIG. 11 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
         [0043]    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.