Abstract:
A transmission having an input member, an output member, at least 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 actuatable in combinations of three to establish a plurality of forward gear ratios and one reverse gear ratio.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/597,393, filed Feb. 10, 2012, which is hereby incorporated in its entirety herein by reference. 
    
    
     FIELD 
     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 transmission having four planetary gear sets, a plurality of torque transmitting devices and ten or more speeds. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     A typical multiple speed transmission uses a combination of friction clutches, 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. 
     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 
     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. 
     In another aspect of the present invention, the transmission has an output member continuously interconnecting the carrier member of the fourth planetary gear set and with the ring gear of the third planetary gear set. 
     In still another aspect of the present invention, the transmission has a first interconnecting member continuously interconnecting the sun gear of the first planetary gear set with the sun gear of the second planetary gear set. 
     In still another aspect of the present invention, the transmission has a second interconnecting member continuously interconnecting the carrier member of the first planetary gear set with the ring gear of the fourth planetary gear set. 
     In still another aspect of the present invention, the transmission has a third interconnecting member continuously interconnecting the ring gear of the second planetary gear set with the sun gear of the third planetary gear set. 
     In still another aspect of the present invention, the transmission has a fourth interconnecting member continuously interconnecting the ring gear of the third planetary gear set with the carrier member of the fourth planetary gear set. 
     In still another aspect of the present invention, the transmission has a first torque transmitting device selectively engageable to interconnect the carrier member of the second planetary gear set and the input member with the sun gear of the fourth planetary gear set. 
     In still another aspect of the present invention, the transmission has a second torque transmitting device selectively engageable to interconnect the ring gear of the second planetary gear set and the sun gear of the third planetary gear set with the sun gear of the fourth planetary gear set. 
     In still another aspect of the present invention, the transmission has a third torque transmitting device selectively engageable to interconnect the carrier member of the first planetary gear set and the ring gear of the fourth planetary gear set with the sun gear of the third planetary gear set. 
     In yet another aspect of the present invention, the transmission has a fourth torque transmitting device selectively engageable to interconnect the carrier member of the first planetary gear set and the ring gear of the fourth planetary gear set with the carrier member of the third planetary gear set. 
     In yet another aspect of the present invention, the transmission has a fifth torque transmitting device selectively engageable to interconnect the sun gear of the first planetary gear set and the sun gear of the second planetary gear set with the stationary member. 
     In yet another aspect of the present invention, the transmission has a sixth torque transmitting device selectively engageable to interconnect the ring gear of the first planetary gear set with the stationary member. 
     In yet another aspect of the present invention, the torque transmitting devices of the transmission are each selectively engageable in combinations of at least three to establish a plurality forward speed ratios and at least one reverse speed ratio between the input member and the output member. 
     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 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a diagrammatic illustration of an embodiment of a ten speed transmission according to the present invention; and 
         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 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     At the outset, it should be appreciated that the embodiments of the multi-speed automatic transmissions of the present invention have an arrangement of permanent mechanical connections between the elements of the four planetary gear sets. For example, a first component or element of the first planetary gear set is permanently coupled a first component or element of the second planetary gear set. A second component or element of a first planetary gear set is permanently coupled to a third component or element of the fourth planetary gear set. A third component or element of the second planetary gear set is permanently coupled to a first component or element of the third planetary gear set. A third component or element of the third planetary gear set is permanently coupled to a second component or element of the fourth planetary gear set. 
     Referring now to  FIG. 1 , a stick diagram presents a schematic layout of an embodiment of the ten speed transmission  10  according to the present invention. Ten speed transmission  10  includes four planetary gear sets  14 ,  16 ,  18  and  20 . As will be described below, each of the planetary gear sets  14 ,  16 ,  18  and  20  have a components or members such as a sun gear, a carrier member and a ring gear that are either permanently or selectively interconnected through clutches or brakes to each other or to a transmission housing  50 . Transmission  10  is capable of establishing ten gear ratios between an input member  12  and an output member  22 . 
     For example, 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  and a second shaft or interconnecting member  44 . The ring gear member  14 C is connected for common rotation with a third shaft or interconnecting member  46 . The planet carrier member  14 B is connected for common rotation with 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 C. 
     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 second shaft or interconnecting member  44 . The ring gear member  16 C is connected for common rotation with a fifth shaft or interconnecting member  52 . The planet carrier member  16 B is connected for common rotation with the input member  12 . 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. 
     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 a fifth shaft or interconnecting member  52 . The ring gear member  18 C is connected for common rotation with a sixth shaft or interconnecting member  54 . The planet carrier member  18 B is connected for common rotation with a seventh 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 C. 
     The planetary gear set  20  includes a sun gear member  20 A, a ring gear member  20 C and a planet gear carrier member  20 B 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 an eighth shaft or interconnecting member  58 . The ring gear member  20 C is connected for common rotation with the fourth shaft or interconnecting member  48 . The planet carrier member  20 B is connected for common rotation with the sixth shaft or interconnecting member  54  and with the output shaft or 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. 
     The input shaft or member  12  is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown) or to launch device, such as a clutch. The output shaft or member  22  is continuously connected with the final drive unit or transfer case (not shown). Transmission housing  50  supports the planetary gear sets and is bolted or otherwise fastened to the engine. 
     The torque-transmitting mechanisms or clutches  24 ,  26 ,  28 ,  30  and brakes  32  and  34  allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. For example, the first clutch  24  is selectively engageable to connect the input shaft or member  12  with the eighth shaft or interconnecting member  58 . The second clutch  26  is selectively engageable to connect the fifth shaft or interconnecting member  52  with the eighth shaft or interconnecting member  58 . The third clutch  28  is selectively engageable to connect the fourth shaft or interconnecting member  48  with the fifth shaft or interconnecting member  52 . The fourth clutch  30  is selectively engageable to connect the fourth shaft or interconnecting member  48  with the seventh shaft or interconnecting member  56 . The first brake  32  is selectively engageable to connect the first shaft or interconnecting member  42  with the stationary element or the transmission housing  50  in order to restrict the member  42  from rotating relative to the transmission housing  50 . The second brake  34  is selectively engageable to connect the third shaft or interconnecting member  46  with the stationary element or the transmission housing  50  in order to restrict the member  46  from rotating relative to the transmission housing  50 . 
     Referring now to  FIG. 1  and  FIG. 2 , the operation of the ten speed transmission  10  will be described. It will be appreciated that transmission  10  is capable of transmitting torque from the input shaft or member  12  to the output shaft or member  22  in at least ten 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  24 , second clutch  26 , third clutch  28 , fourth clutch  30 , first brake  32  and second brake  34 ), as will be explained below.  FIG. 2  is a truth table presenting the various combinations of torque-transmitting mechanisms that are activated or engaged to achieve the various gear states. An “X” in the box means that the particular clutch or brake is engaged to achieve the desired gear state. An “O” represents that the particular torque transmitting device (i.e. a brake or clutch) is on or active, but not carrying torque. 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 . Of course, other gear ratios are achievable depending on the gear diameter, gear teeth count and gear configuration selected. 
     For example to establish a reverse gear, the fourth clutch  30 , first brake  32  and second brake  34  are engaged or activated. The fourth clutch  30  connects the fourth shaft or interconnecting member  48  with the seventh shaft or interconnecting member  56 . The first brake  32  connects the first shaft or interconnecting member  42  with the stationary element or the transmission housing  50  in order to restrict the member  42  from rotating relative to the transmission housing  50 . The second brake  34  connects the third shaft or interconnecting member  46  with the stationary element or the transmission housing  50  in order to restrict the member  46  from rotating relative to the transmission housing  50 . Likewise, the ten forward ratios are achieved through different combinations of clutch and brake engagement, as shown in  FIG. 2 . 
     It will be appreciated that the foregoing explanation of operation and gear states of the ten speed transmission  10  assumes, first of all, that all the clutches 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 engaged or activated in both gear states will remain engaged or activated. 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.