Abstract:
A transmission is provided having an input member, an output member, three 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.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 61/333,026, filed on May 10, 2010, 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 three planetary gear sets and a plurality of torque transmitting devices that are configured to establish at least nine or more forward 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, three planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. The torque transmitting devices are for example clutches and brakes. 
     In another embodiment of the present invention, the first, second, and third planetary gear sets each have a sun gear, a carrier and a ring gear members. Moreover, the input member is continuously interconnected to the sun gear member of the third planetary gear set and the output member is continuously interconnected to the carrier member of the second planetary gear set and the ring gear member of the third planetary gear set. 
     In yet another embodiment of the present invention, a first interconnecting member is continuously interconnected the sun gear member of the first planetary gear set with a stationary member. 
     In yet another embodiment of the present invention, a second interconnecting member is continuously interconnected the ring gear member of the first planetary gear set with the ring gear member of the second planetary gear set. 
     In yet another embodiment of the present invention, a third interconnecting member is continuously interconnected the carrier member of the second planetary gear set with the ring gear member of the third planetary gear set. 
     In still another embodiment of the present invention, a first torque transmitting mechanism is selectively engageable to interconnect the carrier member of the first planetary gear set with the sun gear member of the third planetary gear set and the input member. 
     In still another embodiment of the present invention, a second torque transmitting mechanism selectively engageable to interconnect the carrier member of the first planetary gear set with the carrier member of the third planetary gear set. 
     In still another embodiment of the present invention, a third torque transmitting mechanism selectively engageable to interconnect the sun gear member of the second planetary gear set with the carrier member of the third planetary gear set. 
     In still another embodiment of the present invention, a fourth torque transmitting mechanism selectively engageable to interconnect the sun gear member of the second planetary gear set with the sun gear member of the third planetary gear set and the input member. 
     In still another embodiment of the present invention, a fifth torque transmitting mechanism selectively engageable to interconnect the sun gear member of the second planetary gear set with the stationary member. 
     In still another embodiment of the present invention, a sixth torque transmitting mechanism selectively engageable to interconnect ring gear member of the first planetary gear set and the ring gear member of the second planetary gear set with the stationary member. 
     In still another embodiment of the present invention, the torque transmitting mechanisms are selectively engageable in combinations of at least two to establish at least nine forward speed ratios and at least one reverse speed ratio between the input member and the output member. 
     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 
       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 lever diagram of an embodiment of a nine speed transmission according to the present invention; 
         FIG. 2  is a diagrammatic illustration of an embodiment of a nine speed transmission according to the present invention; and 
         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 . 
     
    
    
     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 nine speed automatic transmission of the present invention have an arrangement of permanent mechanical connections between the elements of the three planetary gear sets. For example, a first component or element of a first planetary gear set is permanently coupled to a third component or element of the second planetary gear set. Further, a second component or element of the second planetary gear set is permanently coupled to a second component or element of the third planetary gear set. 
     Referring now to  FIG. 1 , an embodiment of a nine 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. 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. 
     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 an output shaft or member  22 . The first planetary gear set  14  has three nodes: a first node  14 A, a second node  14 B and a third node  14 C. The second planetary gear set  16  has three nodes: a first node  16 A, a second node  16 B and a third node  16 C. The third planetary gear set  18  has three nodes: a first node  18 A, a second node  18 B and a third node  18 C. 
     The input member  12  is continuously coupled to the first node  18 A of the third planetary gear set  18 . The output member  22  is continuously coupled to the second node  16 B of the second planetary gear set  16  and the second node  18 B of the third planetary gear set  18 . The first node  14 A of the first planetary gear set  14  is coupled to the third node  16 C of the second planetary gear set  16 . The third node  14 C of the first planetary gear set  14  is coupled to a stationary member or ground  50 . The second node  16 B of the second planetary gear set  16  is coupled to the second node  18 B of the third planetary gear set  18 . 
     A first clutch  26  selectively connects the second node  14 B of the first planetary gear set  14  and the input member or shaft  12  with the first node  18 A of the third planetary gear set  18 . A second clutch  28  selectively connects the second node  14 B of the first planetary gear set  14  with the third node  18 C of the third planetary gear set  18 . A third clutch  30  selectively connects the first node  16 A of the second planetary gear set  16  with the third node  18 C of the third planetary gear set  18 . A fourth clutch  32  selectively connects the first node  16 A of the second planetary gear set  16  with the input member or shaft  12  and the first node  18 A of the third planetary gear set  18 . A first brake  34  selectively connects the first node  16 A of the second planetary gear set  16  with a stationary member or transmission housing  50 . A second brake  36  selectively connects the first node  14 A of the first planetary gear set  14  and the third node  16 C of the second planetary gear set  16  with the stationary member or transmission housing  50 . 
     Referring now to  FIG. 2 , a stick diagram presents a schematic layout of the embodiment of the nine 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 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. 
     For example, the planetary gear set  14  includes a sun gear member  14 C, a ring gear member  14 A 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 C is connected for common rotation with a first shaft or interconnecting member  42 . The ring gear member  14 A is connected for common rotation with a second shaft or interconnecting member  44 . The planet carrier member  14 B is connected for common rotation with a third shaft or interconnecting member  46 . The planet gears  14 D are each configured to intermesh with both the sun gear member  14 C and the ring gear member  14 A. 
     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  18 D (only one of which is shown). The sun gear member  16 A is connected for common rotation with a fourth shaft or interconnecting member  48  and a fifth shaft or interconnecting member  52 . The ring gear member  16 C is connected for common rotation with the second shaft or interconnecting member  44 . The planet carrier member  16 B is connected for common rotation with a sixth shaft or interconnecting member  54  and a seventh shaft or interconnecting member  56 . 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 B and a planet gear carrier member  18 C that rotatably supports a first set of planet gears  18 D (only one of which is shown) and a second of planet gears  18 E (only one of which is shown). The sun gear member  18 A is connected for common rotation with an eighth shaft or interconnecting member  58  and with input member or shaft  12 . The ring gear member  18 B is connected for common rotation with the seventh shaft or interconnecting member  56 . The planet carrier member  18 C is connected for common rotation with the ninth shaft or interconnecting member  60  and with a tenth shaft or interconnecting member  62 . The first set of planet gears  18 D are each configured to intermesh with both the ring gear member  18 B and the second set of planet gears  18 E. The second set of planet gears  18 E are each configured to intermesh with both the sun gear member  18 A and the first set of planet gears  18 D. 
     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). 
     The torque-transmitting mechanisms or clutches  26 ,  28 ,  30 ,  32  and brakes  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 third shaft or interconnecting member  46  with the eighth shaft or interconnecting member  58 . The second clutch  28  is selectively engageable to connect the third shaft or interconnecting member  46  with the tenth shaft or interconnecting member  62 . The third clutch  30  is selectively engageable to connect the fifth shaft or interconnecting member  52  with the ninth shaft or interconnecting member  60 . The fourth clutch  32  is selectively engageable to connect the input shaft or member  12  with the fourth shaft or interconnecting member  48 . The first brake  34  is selectively engageable to connect the fourth shaft or interconnecting member  48  with the stationary element or the transmission housing  50  in order to restrict the member  48  from rotating relative to the transmission housing  50 . The second brake  36  is selectively engageable to connect the second shaft or interconnecting member  44  with the stationary element or the transmission housing  50  in order to restrict the member  44  from rotating relative to the transmission housing  50 . 
     Referring now to  FIG. 2  and  FIG. 3 , the operation of the embodiment of the nine 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 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 , third clutch  30 , fourth clutch  32 , first brake  34  and second 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. 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 . 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. 
     To establish a reverse gear, third clutch  30  and second brake  36  are engaged or activated. The third clutch  30  connects the fifth shaft or interconnecting member  52  with the ninth shaft or interconnecting member  60 . The second brake  36  connects the second shaft or interconnecting member  44  with the stationary element or the transmission housing  50  in order to restrict the member  44  from rotating relative to the transmission housing  50 . Likewise, the nine forward ratios are achieved through different combinations of clutch and brake engagement, as shown in  FIG. 3 . 
     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 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.