Patent Publication Number: US-8968145-B2

Title: Multi-speed transmission

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/619,969 filed Apr. 4, 2012. The disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The invention relates generally to a multiple speed transmission, and more particularly, to a transmission having a plurality speeds, planetary gear sets and torque transmitting devices. 
     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, 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 may be, for example, clutches and brakes. 
     In an aspect of the transmission of the present invention, first, second, third and fourth planetary gear sets each have a sun gear, a carrier member and a ring gear. 
     In another aspect of the transmission of the present invention, the input member is continuously connected for common rotation with the sun gear of the first planetary gear set. 
     In still another aspect of the transmission of the present invention, the output member is continuously connected for common rotation with the ring gear of the fourth planetary gear set. 
     In still another aspect of the transmission of the present invention, a first interconnecting member continuously interconnects the carrier member of the first planetary gear set with the ring gear of the third planetary gear set. 
     In still another aspect of the transmission of the present invention, a second interconnecting member continuously interconnects the ring gear of the first planetary gear set with the carrier member of the second planetary gear set. 
     In still another aspect of the transmission of the present invention, a third interconnecting member continuously interconnects the ring gear of the second planetary gear set with the carrier member of the third planetary gear set and the sun gear of the fourth planetary gear set. 
     In yet another aspect of the transmission of the present invention, a first torque transmitting mechanism is selectively engageable to interconnect the sun gear of the first planetary gear set and the input member with the carrier member of the fourth planetary gear set. 
     In yet another aspect of the transmission of the present invention, a second torque transmitting mechanism is selectively engageable to interconnect the carrier member of the first planetary gear set and the sun gear of the third planetary gear set with the carrier member of the fourth planetary gear set. 
     In yet another aspect of the transmission of the present invention, a third torque transmitting mechanism is selectively engageable to interconnect the ring gear of the second planetary gear set and the carrier member of the third planetary gear set with the sun gear of the second planetary gear set. 
     In yet another aspect of the transmission of the present invention, the third torque transmitting mechanism is selectively engageable to interconnect the ring gear of the second planetary gear set and the carrier member of the third planetary gear set with the carrier member of the second planetary gear set. 
     In yet another aspect of the transmission of the present invention, the third torque transmitting mechanism is selectively engageable to interconnect the carrier member of the second planetary gear set and the ring gear of the first planetary gear set with the sun gear of the second planetary gear set. 
     In yet another aspect of the transmission of the present invention, a fourth torque transmitting mechanism is selectively engageable to interconnect the carrier member of the fourth planetary gear set with the stationary member. 
     In yet another aspect of the transmission of the present invention, a fifth torque transmitting mechanism is selectively engageable to interconnect the sun gear of the third planetary gear set with the stationary member. 
     In yet another aspect of the transmission of the present invention, a sixth torque transmitting mechanism is selectively engageable to interconnect the sun gear of the second planetary gear set with the stationary member. 
     In yet another aspect of the transmission of the present invention, the torque transmitting mechanisms are selectively engageable in combinations of at least three to establish a plurality of forward speed ratios and at least one reverse speed ratio between the input member and the output member. 
     The clutches and brakes can be of any type including but not limited to a fiction clutch, a friction band, a one way clutch, a selectable one way clutch, a dog clutch, a synchronizer and similar devices. Furthermore, any node can use a single device or a combination of these devices e.g. the first brake may be configured as a dog clutch and a one way clutch combination or a one way clutch and friction clutch combination. Similarly, several other combinations are possible. 
     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 lever diagram of an embodiment of a transmission according to the principles of present invention; 
         FIG. 2  is a diagrammatic illustration of a variation of the transmission of  FIG. 1  according to the principles of the present invention; 
         FIG. 3  is a truth table presenting an example of a state of engagement of various torque transmitting elements to produce eleven forward and at least one reverse speed or gear ratios of the transmissions illustrated in  FIGS. 1-2 ; and 
         FIGS. 4A ,  4 B,  5 A,  5 B,  6 A and  6 B are diagrammatic illustrations of various interconnections of the third clutch  28  according to the principles of the present invention. 
     
    
    
     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 eleven speed automatic transmission of the present invention have an arrangement of permanent mechanical connections between the elements of the four planetary gear sets. As used herein, coupling or interconnection refers to a direct, continuous, and permanent coupling or interconnection, for example by a rigid member or shaft, between elements. Selective coupling or interconnection, on the other hand, refers to a selective coupling by a clutch or brake, where the clutch or brake can be engaged and disengaged, such that when engaged, the selectively coupled or interconnected elements rotate together, but when disengaged, the selectively coupled or interconnected elements are free to rotate independently. 
     In one embodiment, a second component or element of a first planetary gear set is permanently coupled to a first component or element of a third planetary gear set. A third component or element of the first planetary gear set is permanently coupled to a second component or element of a second planetary gear set. A first component or element of the second planetary gear set is permanently coupled to a second component or element of a third planetary gear set and to a third component or element of a fourth planetary gear set. 
     Referring now to  FIG. 1 , an embodiment of an eleven 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. In some cases, two levers may be combined into a single lever having more than three nodes (typically four nodes). For example, if two nodes on two different levers are interconnected through a fixed connection they may be represented as a single node on a single lever. 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 , a fourth planetary gear set  20 , and an output shaft or member  22 . In the lever diagram of  FIG. 1 , 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 fourth planetary gear set  20  has three nodes: a first node  20 A, a second node  20 B and a third node  20 C. 
     The input member  12  is continuously coupled to the first node  14 A of the first planetary gear set  14 . The output member  22  is continuously coupled to the first node  20 A of the fourth planetary gear set  20 . 
     The second node  14 B of the first planetary gear set  14  is coupled to the first node  18 A of the third planetary gear set  18 . The third node  14 C of the first planetary gear set  14  is coupled to the second node  16 B of the second planetary gear set  16 . The first node  16 A of the second planetary gear set  16  is coupled to the third node  18 B of the third planetary gear set  18  and to the third node  20 C of the fourth planetary gear set  20 . 
     A first clutch  24  selectively connects the first node  14 A of the first planetary gear set  14  with the second node  20 B of the fourth planetary gear set  20 . A second clutch  26  selectively connects the second node  14 B of the first planetary gear set  14  and the first node  18 A of the third planetary gear set  18  with the second node  20 B of the fourth planetary gear set  20 . A third clutch  28  selectively connects the third node  14 C of the first planetary gear set  14  and the second node  16 B of the second planetary gear set  16  with the third node  16 C of the second planetary gear set  16 . 
     A first brake  32  selectively connects the second node  20 B of the fourth planetary gear set  20  with the stationary member or transmission housing  50 . A second brake  34  selectively connects the third node  18 C of the third planetary gear set  18  with the stationary member or transmission housing  50 . A third brake  36  selectively connects 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 an embodiment of the eleven speed transmission  10  according to one form of 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 first planetary gear set  14  includes a sun gear member  14 A, a ring gear member  14 B, and a planet gear carrier member  14 C 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 the input shaft or member  12 . The ring gear member  14 C is connected for common rotation with a first shaft or interconnecting member  42 . The planet carrier member  14 B is connected for common rotation with a second shaft or interconnecting member  44 . The set of 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 second planetary gear set  16  includes a sun gear member  16 C, a ring gear member  16 A, and a planet gear carrier member  16 B that rotatably supports a set of planetary gears  16 D (only one of each is shown). The sun gear member  16 C is connected for common rotation with the third shaft or interconnecting member  46 . The ring 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 planet carrier member  16 B is connected for common rotation with the first shaft or interconnecting member  42 . The planet gears  16 D are each configured to intermesh with both the ring gear member  16 A and the sun gear member  16 C. 
     The third planetary gear set  18  includes a sun gear member  18 C, a ring gear member  18 A, 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 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 the sixth shaft or interconnecting member  52  and a seventh shaft or interconnecting member  56 . The ring gear member  18 A is connected for common rotation with the second shaft or interconnecting member  44 . The planet gears  18 D are each configured to intermesh with both the sun gear member  18 C and the ring gear member  18 A. 
     The fourth planetary gear set  20  includes a sun gear member  20 C, a ring gear member  20 A 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 C is connected for common rotation with the seventh shaft or interconnecting member  56 . The ring gear member  20 A is connected for common rotation with the output shaft or member  22 . The planetary gear carrier member  20 B is connected for common rotation with an eighth shaft or interconnecting member  58  and a ninth shaft or interconnecting member  60 . The planet gears  20 D are each configured to intermesh with both the sun gear member  20 C and the ring gear member  20 A. 
     The input shaft or member  12  is continuously connected to an input source, such as an engine (not shown) or a turbine of a torque converter (not shown). The output shaft or member  22  is continuously connected with another output such as the final drive unit or transfer case (not shown). 
     The torque-transmitting mechanisms, including the first, second, and third clutches  24 ,  26 ,  28  and the first, second and third brakes  32 ,  34  and  36  allow for selective interconnection of the shafts or interconnecting members  42 ,  44 ,  46 ,  48 ,  52 ,  54 ,  56 ,  58  and  60  of the planetary gear sets  14 ,  16 ,  18 ,  20  and the housing  50 . 
     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 second shaft or interconnecting member  44  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 third shaft or interconnecting member  46 . 
     The first brake  32  is selectively engageable to connect the ninth shaft or interconnecting member  60  with the stationary element or the transmission housing  50  in order to restrict the member  60  from rotating relative to the transmission housing  50 . The second brake  34  is selectively engageable to connect the sixth shaft or interconnecting member  54  with the stationary element or the transmission housing  50  in order to restrict the member  54  from rotating relative to the transmission housing  50 . The third brake  36  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 . In turn, the components of the planetary gear sets connected to each of the connecting members are also connected or restricted accordingly. 
     Referring now to  FIG. 2  and  FIG. 3 , the operation of the eleven speed transmission  10  embodiment 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 eleven or more forward speed 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 , first brake  32 , second brake  34  and third 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. 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 third clutch  28 , the first brake  32  and the second brake  34  are engaged or activated. The third clutch  28  connects the third shaft or interconnecting member  46  with the fourth shaft or interconnecting member  48 . The first brake  32  connects the ninth shaft or interconnecting member  60  with the stationary element or the transmission housing  50  in order to restrict the member  60  from rotating relative to the transmission housing  50 , which restricts the carrier member  20 B from rotating relative to the transmission housing  50 . The second brake  34  connects the sixth shaft or interconnecting member  54  with the stationary element or the transmission housing  50  in order to restrict the member  54  from rotating relative to the transmission housing  50 , which restricts the sun gear  18 C from rotating relative to the transmission housing  50 . Likewise, eleven forward ratios are achieved through different combinations of clutch and brake engagement, as shown in  FIG. 3 , by way of example. 
     Further, the present invention contemplates that at least one additional reverse gear (REV 2 ) is achievable by the transmission of  FIGS. 1 and 2 . As shown in  FIG. 3 , a second reverse gear ratio is achieved through selective activation or engagement of the first brake  32 , the second brake  34  and the third brake  36 . The first brake  32  connects the ninth shaft or interconnecting member  60  with the stationary element or the transmission housing  50  in order to restrict the member  60  from rotating relative to the transmission housing  50 , which restricts the carrier member  20 B from rotating relative to the transmission housing  50 . The second brake  34  connects the sixth shaft or interconnecting member  54  with the stationary element or the transmission housing  50  in order to restrict the member  54  from rotating relative to the transmission housing  50 , which restricts the sun gear  18 C from rotating relative to the transmission housing  50 . The third brake  36  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 , which restricts the sun gear  16 C from rotating relative to the transmission housing  50 . 
     It will be appreciated that the foregoing explanation of operation and gear states of the eleven speed embodiment of 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. 
     Additionally, the present invention contemplates other embodiments of transmission  10  having different interconnections for the third clutch  28  as illustrated in  FIGS. 4A ,  4 B,  5 A,  5 B,  6 A and  6 B. For example, in  FIG. 4A  a transmission  10 ′ has the third clutch  28  selectively interconnecting the second node  16 B of the second planetary gear set  16  with the first node  16 A of the second planetary gear set  16 . In  FIG. 4B , transmission  10 ′ has the third clutch  28  selectively interconnecting the carrier member  16 B of the second planetary gear set  16  with the ring gear  16 A of the second planetary gear set  16 . In  FIG. 5A , a transmission  10 ″ has the third clutch  28  selectively interconnecting the third node  16 C of the second planetary gear set  16  with the first node  16 A of the second planetary gear set  16 . In  FIG. 5B , the transmission  10 ″ has the third clutch  28  selectively interconnecting the sun gear  16 C of the second planetary gear set  16  with the ring gear  16 A of the second planetary gear set  16 . In  FIG. 6A , transmission  10 ′″ has the third clutch  28  selectively interconnecting the third node  16 C of the second planetary gear set  16  with the second node  16 B of the second planetary gear set  16 . In  FIG. 6B , transmission  10 ′″ has the third clutch  28  selectively interconnecting the sun gear  16 C of the second planetary gear set  16  with the carrier member  16 B of the second planetary gear set  16 . 
     In yet another embodiment of the present invention, transmissions  10 ,  10 ′,  10 ″ and  10 ′″ may have input shafts or members  12  connected to a torque converter or directly to the engine. In the case where the input shaft is directly connected to the engine and no torque converter is provided the third clutch  28  is used as a vehicle launch clutch. For example, when starting the vehicle from rest in first gear first clutch  26  and first brake  32  are engaged and third clutch  28  is allowed to slip (by not being fully engaged). To launch the vehicle third clutch  28  is fully engaged. When the vehicle is at rest and shifted into reverse the first and second brakes  32  and  34  are engaged and the third clutch  28  is allowed to slip until the third clutch is fully engaged and the vehicle is launched in reverse. 
     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.