Abstract:
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 may include clutches and brakes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application is a continuation of U.S. application Ser. No. 11/970,159 filed on Jan. 7, 2008, which claims the benefit of U.S. Provisional Application No. 60/900,613 filed on Feb. 8, 2007. The disclosures of the above applications are incorporated herein by reference. 
     
    
     TECHNICAL 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 transmission having nine or more speeds, 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, 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 may include clutches and brakes. 
         [0007]    One embodiment of the present invention includes an input member, an output member, first, second, third and fourth planetary gear sets each having first, second and third members, a first interconnecting member continuously interconnecting the third member of the first planetary gear set with the first member of the second planetary gear set, a second interconnecting member continuously interconnecting the third member of the second planetary gear set with the second member of the third planetary gear set, a third interconnecting member continuously interconnecting the third member of the third planetary gear set with the second member of the fourth planetary gear set, and a fourth interconnecting member continuously interconnecting the first member of the third planetary gear set with the first member of the fourth planetary gear set. Six torque transmitting mechanisms are selectively engageable to interconnect one of the first, second, and third members with another of the first, second, third members, and a stationary element. The torque transmitting mechanisms are selectively engageable in combinations of at least three to establish at least nine forward speed ratios and at least one reverse speed ratio between the input member and the output member. 
         [0008]    In one aspect of the present invention, a first of the six torque transmitting mechanisms is selectively engageable to interconnect the second member of the first planetary gear set with the second member of the second planetary gear set. 
         [0009]    In another aspect of the present invention, a second of the six torque transmitting mechanisms is selectively engageable to interconnect the second member of the second planetary gear set with the third member of the fourth planetary gear set. 
         [0010]    In yet another aspect of the present invention, a third of the six torque transmitting mechanisms is selectively engageable to interconnect at least one of the input member and the second member of the first planetary gear set with at least one of the first member of the third planetary gear set and the first member of the fourth planetary gear set. 
         [0011]    In yet another aspect of the present invention, a fourth of the six torque transmitting mechanisms is selectively engageable to interconnect at least one of the third member of the first planetary gear set and the first member of the second planetary gear set with at least one of the first member of the third planetary gear set and the first member of the fourth planetary gear set. 
         [0012]    In yet another aspect of the present invention, a fifth of the six torque transmitting mechanisms is selectively engageable to interconnect the first member of the first planetary gear set with the stationary element. 
         [0013]    In yet another aspect of the present invention, a sixth of the six torque transmitting mechanisms is selectively engageable to interconnect the third member of the fourth planetary gear set with the stationary element. 
         [0014]    In yet another aspect of the present invention, the first members are sun gears, the second members are carrier members, and the third members are ring gears. 
         [0015]    In yet another aspect of the present invention, the input member is continuously interconnected with the second member of the first planetary gear set and wherein the output member is continuously interconnected with the second member of the fourth planetary gear set. 
         [0016]    In yet another aspect of the present invention, two of the torque transmitting mechanisms are brakes and four of the torque transmitting mechanisms are clutches. 
         [0017]    In yet another aspect of the present invention, the stationary element is a transmission housing. 
         [0018]    Another embodiment of the transmission includes an input member, an output member, first, second, third and fourth planetary gear sets each having a sun gear, a carrier member, and a ring gear, wherein the input member is continuously interconnected with the carrier member of the first planetary gear set and wherein the output member is continuously interconnected with the carrier member of the fourth planetary gear set, a first interconnecting member continuously interconnecting the ring gear of the first planetary gear set with the sun gear of the second planetary gear set, a second interconnecting member continuously interconnecting the ring gear of the second planetary gear set with the carrier member of the third planetary gear set, a third interconnecting member continuously interconnecting the ring gear of the third planetary gear set with the carrier member of the fourth planetary gear set, and a fourth interconnecting member continuously interconnecting the sun gear of the third planetary gear set with the sun gear of the fourth planetary gear set. A first torque transmitting mechanism is selectively engageable to interconnect the carrier member of the first planetary gear set with the carrier member of the second planetary gear set, a second torque transmitting mechanism is selectively engageable to interconnect the carrier member of the second planetary gear set with the ring gear of the fourth planetary gear set, a third torque transmitting mechanism is selectively engageable to interconnect at least one of the input member and the carrier member of the first planetary gear set with at least one of the sun gear of the third planetary gear set and the sun gear of the fourth planetary gear set, a fourth torque transmitting mechanism is selectively engageable to interconnect at least one of the ring gear of the first planetary gear set and the sun gear of the second planetary gear set with at least one of the sun gear of the third planetary gear set and the sun gear of the fourth planetary gear set, a fifth torque transmitting mechanism is selectively engageable to interconnect the sun gear of the first planetary gear set with a stationary element, and a sixth torque transmitting mechanism is selectively engageable to interconnect the ring gear of the fourth planetary gear set with the stationary element. The torque transmitting mechanisms are selectively engageable in combinations of at least three to establish at least nine forward speed ratios and at least one reverse speed ratio between the input member and the output member. 
         [0019]    The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0021]      FIG. 1  is a lever diagram of an embodiment of a multiple speed transmission according to the present invention; 
           [0022]      FIG. 2  is a diagrammatic view of an embodiment of a multiple speed transmission according to the present invention; 
           [0023]      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 ; and 
           [0024]      FIG. 4  is an alternate 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 . 
       
    
    
     DESCRIPTION 
       [0025]    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 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 an 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. 
         [0026]    The transmission  10  includes an input shaft or member  12 , an output shaft or member  14 , a first planetary gear set  16  having three nodes: a first node  24 , a second node  26  and a third node  28 , a second planetary gear set  18  having three nodes: a first node  42 , a second node  44  and a third node  46 , a third planetary gear set  20  having three nodes: a first node  52 , a second node  54  and a third node  56 , and a fourth planetary gear set  22  having three nodes: a first node  72 , a second node  74  and a third node  76 . 
         [0027]    The input member  12  is coupled to the third node  28  of the first planetary gear set  16 . The output  14  is coupled to the third node  76  of the fourth planetary gear set  22 . The second node  26  of the first planetary gear set  16  is coupled to the first node  42  of the second planetary gear set  18 . The second node  44  of the second planetary gear set  18  is coupled to the third node  56  of the third planetary gear set  20 . The first node  52  of the third planetary gear set  20  is coupled to the first node  72  of the fourth planetary gear set  22 . The second node  54  of the third planetary gear set  20  is coupled to the third node  76  of the fourth planetary gear set  22 . 
         [0028]    A first clutch  80  selectively connects the third node  28  of the first planetary gear set  16  to the third node  46  of the second planetary gear set  18 . A second clutch  82  selectively connects the third node  46  of the second planetary gear set  18  to the second node  74  of the fourth planetary gear set  22 . A third clutch  84  selectively connects the input member  12  to the first node  52  of the third planetary gear set  20 . A fourth clutch  86  selectively connects the first node  42  of the second planetary gear set  18  to the first node  52  of the third planetary gear set  20 . A first brake  90  selectively connects the first node  24  of the first planetary gear set  16  to a ground, stationary element, or a transmission housing  100 . A second brake  92  selectively connects the second node  74  of the fourth planetary gear set  22  to a ground, stationary element, or the transmission housing  100 . 
         [0029]    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. 
         [0030]    For example, the first planetary gear set  16  includes a sun gear member  24 , a ring gear member  26  and a carrier member  28  that rotatably supports a set of pinion gears  30  (only one shown). Each of the pinion gears  30  are configured to intermesh with both sun gear member  24  and ring gear member  26 . Sun gear member  24  is connected for common rotation with a first interconnecting shaft or member  32 . Ring gear member  26  is connected for common rotation with a second interconnecting shaft or member  34 . Carrier member  28  is connected for common rotation with a third interconnecting shaft or member  36  and with input shaft  12 . 
         [0031]    The second planetary gear set  18  includes a sun gear member  42 , a ring gear member  44  and a carrier member  46  that rotatably supports a set of pinion gears  48 . Each of the pinion gears  48  are configured to intermesh with both sun gear member  42  and ring gear member  44 . Sun gear member  42  is connected for common rotation with a fourth interconnecting shaft or member  38 . Ring gear member  44  is connected for common rotation with a fifth interconnecting shaft or member  50 . Carrier member  46  is connected for common rotation with a sixth interconnecting shaft or member  60 . 
         [0032]    The third planetary gear set  20  includes a sun gear member  52 , a ring gear member  54  and a carrier member  56  that rotatably supports a set of pinion gears  58 . Each of the pinion gears  58  are configured to intermesh with both sun gear member  52  and ring gear member  54 . Sun gear member  52  is connected for common rotation with a seventh interconnecting shaft or member  62 . Ring gear member  54  is connected for common rotation with an eighth interconnecting shaft or member  64 . Carrier member  56  is connected for common rotation with fifth interconnecting member  50 . 
         [0033]    The fourth planetary gear set  22  includes a sun gear member  72 , a ring gear member  74  and a carrier member  76  that rotatably supports a set of pinion gears  78 . Each of the pinion gears  78  are configured to intermesh with both sun gear member  72  and ring gear member  74 . Sun gear member  72  is connected for common rotation with seventh interconnecting member  62 . Ring gear member  74  is connected for common rotation with a ninth interconnecting shaft or member  66 . Carrier member  76  is connected for common rotation with eighth interconnecting member  64  and with output shaft  14 . 
         [0034]    The input shaft  12  is continuously connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output shaft  14  is continuously connected with the final drive unit (not shown). 
         [0035]    The transmission  10  includes a variety of torque-transmitting mechanisms or devices including a first clutch  80 , a second clutch  82 , a third clutch  84 , a fourth clutch  86 , a first brake  90  and a second brake  92 . First clutch  80  is selectively engagable to connect third interconnecting member  36  to sixth interconnecting member  60 . Second clutch  82  is selectively engagable to connect sixth interconnecting member  60  to ninth interconnecting member  66 . Third clutch  84  is selectively engagable to connect input shaft  12  to seventh interconnecting member  62 . Fourth clutch  86  is selectively engagable to connect second and fourth interconnecting members  34 ,  38  to seventh interconnecting member  62 . First brake  90  is selectively engagable to connect first interconnecting member  32  to transmission housing  100  to restrict rotation of first interconnecting member  32  and sun gear  24  relative to housing  100 . Second brake  92  is selectively engagable to connect ninth interconnecting member  66  to housing  100  to restrict rotation of ninth interconnecting member  66  and ring gear  74  relative to housing  100 . 
         [0036]    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  14  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  80 , second clutch  82 , third clutch  84 , fourth clutch  86 , first brake  32 , and second brake  34 ), as will be explained below.  FIG. 3  is a truth table presenting the various combinations of torque-transmitting mechanisms or elements that are activated or engaged to achieve the various gear states. Actual numerical gear ratios and gear steps 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. 
         [0037]    To establish reverse gear, the first brake  90 , the second brake  92 , and the second clutch  82  are engaged or activated. First brake  90  connects first interconnecting member  32  to transmission housing  100  to restrict rotation of first interconnecting member  32  and sun gear  24  relative to housing  100 . Second brake  92  connects ninth interconnecting member  66  to housing  100  to restrict rotation of ninth interconnecting member  66  and ring gear  74  relative to housing  100 . Second clutch  82  connects sixth interconnecting member  60  to ninth interconnecting member  66 . Likewise, the nine forward ratios are achieved through different combinations of clutch and brake engagement, as shown in  FIG. 3 . 
         [0038]    Referring now to  FIG. 4 , an alternate truth table is presented for the operation of the embodiment of the multiple speed transmission  10 . 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  14  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  80 , second clutch  82 , third clutch  84 , fourth clutch  86 , first brake  32 , and second brake  34 ), as was described above. Actual numerical gear ratios and gear steps 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. 
         [0039]    It will be appreciated that the foregoing explanation of operation and gear states of the multiple speed transmission  10  assumes, first of all, that all the clutches and the 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. Additionally, the present invention contemplates that downshifts follow essentially the reverse sequence of the corresponding upshift (as described above), and several power-on skip-shifts are possible (e.g. from 1st to 3rd). 
         [0040]    While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.