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 a sun gear member, a planet carrier member, and a ring gear member. The torque transmitting devices include clutches and brakes arranged within a transmission housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/984,531, filed on Nov. 1, 2007, 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 eight or more speeds, three planetary gear sets and a plurality of 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. 
     Automatic power transmissions are currently in widespread use in passenger vehicles and trucks. As is well known, the automatic transmission provides a plurality of speed ratios in the forward direction and at least one speed ratio in the reverse direction. The speed ratios are established through the use of a plurality of planetary gearsets. The engagement of the gearsets is controlled by a number of fluid-operated torque transmitting mechanisms, for example clutches and brakes. 
     It has become a standard to provide at least four forward speed ratios in automatic transmissions for use in passenger vehicles. More recently, automobile manufacturers have increased the forward speed ratios to six and in some instances seven or eight. This, of course, requires the addition of planetary gearsets. However, it is desirable to minimize the number of torque transmitting mechanisms to reduce cost and overall size of the transmission. 
     A number of the currently proposed eight speed planetary transmissions provide three planetary gearsets and six torque-transmitting mechanisms. One problem facing transmission designers and manufacturers is the packaging of the planetary gearsets and the torque-transmitting mechanisms. It is preferable to arrange the gearsets and torque-transmitting mechanisms in a way that minimizes the overall size of the transmission as well as reduces manufacturing complexity. 
     Therefore, there is a need for a new and improved multi-speed transmission. The arrangement of the gearsets and the torque-transmitting mechanisms of the transmission should minimize the size and manufacturing complexity of the transmission. 
     SUMMARY 
     In an aspect of the present invention, a multi-speed transmission is provided. The transmission has an input member, an output member, a transmission housing, a first, second, and third planetary gear set, five clutches and one brake. 
     The transmission housing has a first wall, a second wall, and a third wall extending between the first and second walls. The second planetary gear set is adjacent the first wall. The third planetary gear set is adjacent second wall. The first planetary gear set is between the second and third planetary gear sets. Each planetary gear set has a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with at least one of the sun gear member and the ring gear member. 
     The output member is continuously interconnected with the ring gear member of the third planetary gear set. The input member is continuously interconnected with the sun gear member of the second planetary gear set. 
     The sun gear member of the first planetary gear set is permanently coupled to the transmission housing. The planet carrier member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set. 
     The transmission housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third planetary gear set and the second wall and a fifth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall. 
     The first of the five clutches is selectively engageable to interconnect the input member with the planet carrier member of the first planetary gear set. The second of the five clutches is selectively engageable to interconnect the input member with the ring gear member of the second planetary gear set. The third of the five clutches is selectively engageable to interconnect the planet carrier member of the first planetary gear set with the sun gear member of the third planetary gear set. The fourth of the five clutches is selectively engageable to interconnect the ring gear member of the first planetary gear set with the sun gear member of the third planetary gear set. The fifth of the five clutches is selectively engageable to interconnect the ring gear member of the first planetary gear set with the ring gear member of the second planetary gear set. The brake is selectively engageable to interconnect the planet carrier member of the third planetary gear set to the transmission housing. 
     The first of the five clutches is disposed in at least one of the first, third and fifth areas. The second of the five clutches is disposed in at least one of the first, second and fifth areas. The third of the five clutches is disposed in at least one of the second, third and fifth areas. The fourth of the five clutches is disposed in at least one of the second, third and fifth areas. The fifth of the five clutches is disposed in at least one of the first, second, third and fifth areas. The brake is disposed in at least one of the third, fourth and fifth areas. 
     The clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       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 diagram of a cross-section of a transmission 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. 
     Referring now to  FIG. 1 , an embodiment of a multi-speed transmission is generally indicated by reference number  10 . The transmission  10  includes a transmission housing  11 , an input shaft or member  12 , and an output shaft or member  14 . The input member  12  is preferably connected to an engine (not shown) or to a turbine of a torque converter (not shown). The output member  14  is preferably connected with a final drive unit (not shown) or transfer case (not shown). In the example provided, the output member  14  is coaxial with a longitudinal axis defined by the input member  12 . Accordingly, the output member  14  may exit on an opposite side of the transmission  10  as the input member  12 , thereby providing, for example, a rear wheel drive transmission configuration. 
     The transmission  10  includes a first planetary gear set  16 , a second planetary gear set  18 , and a third planetary gear set  20 . The planetary gear sets  16 ,  18 , and  20  are connected between the input member  12  and the output member  14 . In a preferred embodiment of the present invention, the first planetary gear set  16  is a planetary gear set that includes a sun gear member  22 , a ring gear member  24  and a carrier member  28  that rotatably supports a set of pinion gears  32 ,  34 . Pinion gears  32 ,  34  are configured to intermesh with each other, sun gear member  22  and ring gear member  24 . Moreover, sun gear member  22  is fixedly connected to the transmission housing  11  of the transmission  10  for preventing rotation of sun gear member  22 . Ring gear member  24  is connected for common rotation with a first interconnecting shaft or member  38 . Carrier member  28  is connected for common rotation with a second interconnecting shaft or member  40  and a third interconnecting shaft or member  45 . 
     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 . Pinion gears  48  are each configured to intermesh with both sun gear member  42  and ring gear member  44 . Sun gear member  42  is connected for common rotation with the input member  12  and a fourth interconnecting shaft or member  43 . Carrier member  46  is connected for common rotation with a fifth interconnecting shaft or member  47 . Ring gear member  44  is connected for common rotation with a sixth interconnecting shaft or member  50  and a seventh interconnecting shaft or member  51 . 
     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 . Pinion gears  58  are each configured to intermesh with both sun gear member  52  and ring gear member  54 . Sun gear member  52  is connected for common rotation with an eighth interconnecting shaft or member  60 . Ring gear member  54  is connected for common rotation with the output member  14 . Carrier member  56  is connected for common rotation with the fifth interconnecting member  47  and a ninth interconnecting shaft or member  61 . 
     The transmission  10  includes a variety of torque-transmitting mechanisms or devices including a first clutch  70 , a second clutch  72 , a third clutch  74 , a fourth clutch  76 , a fifth clutch  78 , and a brake  80 . The first clutch  70  is selectively engagable to connect the fourth interconnecting member  43  with the third interconnecting member  45 . The second clutch  72  is selectively engagable to connect the fourth interconnecting member  43  with the seventh interconnecting member  51 . The third clutch  74  is selectively engagable to connect the second interconnecting member  40  with the eighth interconnecting member  60 . The fourth clutch  76  is selectively engagable to connect the first interconnecting member  38  to the eighth interconnecting member  60 . The fifth clutch  78  is selectively engagable to connect the first interconnecting member  38  to the sixth interconnecting member  50 . The brake  80  is selectively engagable to connect carrier member  56  to the transmission housing  11  to restrict rotation of carrier member  56  via the ninth interconnecting member  61 . 
     The transmission  10  is capable of transmitting torque from the input member  12  to the output member  14  in preferably at least eight forward torque ratios and two reverse torque ratios. Each of the forward torque ratios and the reverse torque ratios are attained by engagement of one or more of the torque-transmitting mechanisms (i.e. first clutch  70 , second clutch  72 , third clutch  74 , fourth clutch  76 , fifth clutch  78 , and brake  80 ). Those skilled in the art will readily understand that a different speed ratio is associated with each torque ratio. Thus, eight forward speed ratios may be attained by the transmission  10 . 
     The transmission housing  11  includes a first end wall  102 , a second end wall  104 , and a third wall  106 . The third wall  106  interconnects between the first and second end walls  102  and  104  to provide a space or cavity  108  in which the planetary gear sets  16 ,  18 , and  20  and the torque-transmitting mechanisms  70 ,  72 ,  74 ,  76 ,  78 , and  80  are located. Further, the cavity  108  has a plurality of areas or Zones A, B, C, D, and E in which the plurality of torque transmitting mechanisms  70 ,  72 ,  74 ,  76 ,  78 , and  80  are specifically positioned, in accordance with the preferred embodiments of the present invention. 
     As shown in  FIG. 1 , Zone A is defined by the area or space bounded: axially on the left by the first end wall  102 , on the right by planetary gear set  18 , radially inward by a reference line “L” which is a longitudinal line that is axially aligned with the input shaft  12 , and radially outward by a reference line “M” which is a longitudinal line that extends adjacent an outer diameter or outer periphery of the planetary gear sets  16 ,  18 , and  20 . While reference line “M” is illustrated as a straight line, it should be appreciated that reference line “M” follows the outer periphery of the planetary gear sets  16 ,  18 , and  20 , and accordingly may be stepped or non-linear depending on the location of the outer periphery of each of the planetary gear sets  16 ,  18 , and  20 . Zone B is defined by the area bounded: axially on the left by planetary gear set  18 , axially on the right by planetary gear set  16 , radially outward by reference line “M”, and radially inward by reference line “L”. Zone C is defined by the area bounded: axially on the left by planetary gear set  16 , axially on the right by planetary gear set  20 , radially outward by reference line “M”, and radially inward by reference line “L”. Zone D is defined by the area bounded: axially on the left by planetary gear set  20 , axially on the right by the second end wall  104 , radially outward by reference line “M”, and radially inward by reference line “L”. Zone E is defined by the area bounded: axially on the left by the first end wall  102 , axially on the right by the second end wall  104 , radially inward by reference line “M” and radially outward by the third wall  106 . 
     The torque transmitting mechanisms  70 ,  72 ,  74 ,  76 ,  78 , and  80  are intentionally located within specific Zones in order to provide advantages in overall transmission size, packaging efficiency, and reduced manufacturing complexity. In the particular example shown in  FIG. 1 , the torque transmitting mechanisms  70  and  72  are in Zone A, the torque transmitting mechanisms  74 ,  76 , and  78  are in Zone B, and the torque transmitting mechanism  80  is in Zone C. 
     However, the present invention contemplates other embodiments where the torque transmitting mechanisms  70 ,  72 ,  74 ,  76 ,  78 , and  80  are disposed in the other Zones. The feasible locations of the torque-transmitting devices  70 ,  72 ,  74 ,  76 ,  78 , and  80  relative to the Zones are illustrated in Chart 1. An “X” in the chart indicates that the present invention contemplates locating the particular torque transmitting device in the referenced Zones. An “O” in the chart indicates that the present invention contemplates that it is not feasible to locate the particular torque transmitting device in the referenced Zone. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 CHART 1 
               
               
                   
               
               
                 TORQUE 
                   
                   
                   
                   
                   
               
               
                 TRANSMITTING 
                 ZONE 
                 ZONE 
                 ZONE 
                 ZONE 
                 ZONE 
               
               
                 DEVICES 
                 A 
                 B 
                 C 
                 D 
                 E 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 80 
                 ◯ 
                 ◯ 
                 X 
                 X 
                 X 
               
               
                 78 
                 X 
                 X 
                 X 
                 ◯ 
                 X 
               
               
                 76 
                 ◯ 
                 X 
                 X 
                 ◯ 
                 X 
               
               
                 74 
                 ◯ 
                 X 
                 X 
                 ◯ 
                 X 
               
               
                 70 
                 X 
                 ◯ 
                 X 
                 ◯ 
                 X 
               
               
                 72 
                 X 
                 X 
                 ◯ 
                 ◯ 
                 X 
               
               
                   
               
             
          
         
       
     
     For example, the present invention provides that brake  80  may be located in Zones C, D, or E, but may not be located in Zones A or B. It should be appreciated that each of the torque transmitting devices  70 ,  72 ,  74 ,  76 ,  78 , and  80  may be located in a permissible Zone, as indicated in Chart 1, independently of the location of any of the other torque transmitting devices  70 ,  72 ,  74 ,  76 ,  78 , and  80 . 
     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.