Abstract:
A family of transmission gearing arrangements produces up to nine forward and one reverse speed ratios by selective engagement of three couplers in various combinations. Each disclosed transmission includes four planetary gear sets and six couplers. Three of the couplers may be brakes. Three of the couplers may selectively couple planetary elements to the input shaft.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to the field of automatic transmissions for motor vehicles. More particularly, the disclosure pertains to an arrangement of gears, clutches, and the interconnections among them in a power transmission. 
       BACKGROUND 
       [0002]    Many vehicles are used over a wide range of vehicle speeds in both forward and reverse. Some types of engines, however, are capable of operating efficiently only within a narrow range of speeds. Consequently, transmissions capable of efficiently transmitting power at a variety of speed ratios are frequently employed. When the vehicle is at low speed, the transmission is usually operated at a high speed ratio such that it multiplies the engine torque for improved acceleration. When the vehicle is at high speed, the transmission is usually operated at a low speed ratio to permit the engine to facilitate quiet, fuel efficient cruising. 
         [0003]    Typically, a transmission has a housing mounted to the vehicle structure, an input shaft driven by an engine crankshaft, and an output shaft driving the vehicle wheels, often via a differential assembly which permits the left and right wheel to rotate at slightly different speeds as the vehicle turns. 
       SUMMARY OF THE DISCLOSURE 
       [0000]      
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a schematic diagram of a first transmission gearing arrangement. 
           [0005]      FIG. 2  is a schematic diagram of a second transmission gearing arrangement. 
           [0006]      FIG. 3  is a schematic diagram of a third transmission gearing arrangement. 
       
    
    
     DETAILED DESCRIPTION 
       [0007]    Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations. 
         [0008]    A gearing arrangement is a collection of rotating elements and clutches configured to impose specified speed relationships among elements. Some speed relationships, called fixed speed relationships, are imposed regardless of the state of any clutches. A gearing arrangement imposing only fixed relationships is called a fixed gearing arrangement. Other speed relationships are imposed only when particular clutches are fully engaged. A gearing arrangement that selectively imposes speed relationships is called a shiftable gearing arrangement. A discrete ratio transmission has a shiftable gearing arrangement that selectively imposes a variety of speed ratios between an input shaft and an output shaft. 
         [0009]    A group of elements are fixedly coupled to one another if they are constrained to rotate as a unit in all operating conditions. Elements can be fixedly coupled by spline connections, welding, press fitting, machining from a common solid, or other means. Slight variations in rotational displacement between fixedly coupled elements can occur such as displacement due to lash or shaft compliance. In contrast, two elements are selectively coupled by a clutch when the clutch constrains them to rotate as a unit whenever the clutch is fully engaged and they are free to rotate at distinct speeds in at least some other operating condition. Clutches include actively controlled devices such as hydraulically or electrically actuated clutches and passive devices such as one way clutches. A clutch that holds an element against rotation by selectively connecting the element to the housing may be called a brake. 
         [0010]    An example transmission is schematically illustrated in  FIG. 1 . The transmission utilizes four simple planetary gear sets  20 ,  30 ,  40 , and  50 . A simple planetary gear set is a type of fixed gearing arrangement. A planet carrier  22  rotates about a central axis and supports a set of planet gears  24  such that the planet gears rotate with respect to the planet carrier. External gear teeth on the planet gears mesh with external gear teeth on a sun gear  26  and with internal gear teeth on a ring gear  28 . The sun gear and ring gear are supported to rotate about the same axis as the carrier. A simple planetary gear set imposes a fixed speed relationship. The speed of the carrier is constrained to be between the speed of the sun gear and the speed of the ring gear. (This relationship is defined to include the condition in which all three rotate at the same speed.) More specifically, the speed of the carrier is a weighted average of the speed of the sun gear and the speed of the ring gear with weighting factors determined by the number of teeth on each gear. Similar speed relationships are imposed by other known types of fixed gearing arrangements. For example, a double pinion planetary gear set constrains the speed of the ring gear to be a weighted average between the speed of the sun gear and the speed of the carrier. Gear sets  30 ,  40 , and  50  are similarly structured. 
         [0011]    A suggested ratio of gear teeth for each planetary gear set is listed in Table 1. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
             
               
                   
                 Ring 28/Sun 26 
                 2.05 
               
               
                   
                 Ring 38/Sun 36 
                 1.59 
               
               
                   
                 Ring 48/Sun 46 
                 1.89 
               
               
                   
                 Ring 58/Sun 56 
                 1.89 
               
               
                   
                   
               
             
          
         
       
     
         [0012]    In the transmission of  FIG. 1 , sun gear  26  is fixedly coupled to sun gear  36  by intermediate shaft  72 , ring gear  28  and carrier  32  are fixedly coupled to ring gear  58 , sun gear  46  is fixedly coupled to sun gear  56 , ring gear  48  is fixedly coupled to carrier  52 , and output shaft  12  is fixedly coupled to carrier  42 . Intermediate shaft  72  is selectively held against rotation by brake  66  and selectively coupled to input shaft  10  by clutch  64 . Carrier  22  is selectively held against rotation by brake  70 . Input shaft  10  is selectively coupled to ring gear  38  by clutch  68  and selectively coupled to ring gear  48  and carrier  52  by clutch  62 . Sun gears  46  and  56  are selectively held against rotation by brake  60 . The combination of gear set  20  and brake  70  selectively impose a speed relationship between ring gear  58  and intermediate shaft  72 . Specifically, intermediate shaft  72  and ring gear  58  rotate in opposite directions at proportional speeds whenever brake  70  is engaged. The combination of gear set  30  and clutch  68  selectively impose a speed relationship between ring gear  58 , intermediate shaft  72 , and input shaft  10 . Specifically, ring gear  58  is constrained to rotate at a speed between the speeds of input shaft  10  and intermediate shaft  72  whenever clutch  68  is engaged. 
         [0013]    As shown in Table 2, engaging the clutches and brakes in combinations of three establishes nine forward speed ratios and one reverse speed ratio between input shaft  10  and output shaft  12 . An X indicates that the clutch is required to establish the speed ratio. An (X) indicates the clutch can be applied but is not required. In 4th gear, either clutch  64 , brake  66 , or brake  70  can be applied instead of applying clutch  68  without changing the speed ratio. When the gear sets have tooth numbers as indicated in Table 1, the speed ratios have the values indicated in Table 2. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 60 
                 62 
                 64 
                 66 
                 68 
                 70 
                 Ratio 
                 Step 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Rev 
                 X 
                   
                 X 
                   
                   
                 X 
                 −4.79 
                 70% 
               
               
                   
                 1 st   
                 X 
                   
                   
                   
                 X 
                 X 
                 6.84 
               
               
                   
                 2 nd   
                 X 
                   
                   
                 X 
                 X 
                   
                 3.82 
                 1.79 
               
               
                   
                 3 rd   
                 X 
                   
                 X 
                   
                 X 
                   
                 2.34 
                 1.63 
               
               
                   
                 4 th   
                 X 
                 X 
                   
                   
                 (X) 
                   
                 1.53 
                 1.53 
               
               
                   
                 5 th   
                   
                 X 
                 X 
                   
                 X 
                   
                 1.00 
                 1.53 
               
               
                   
                 6 th   
                   
                 X 
                   
                 X 
                 X 
                   
                 0.80 
                 1.25 
               
               
                   
                 7 th   
                   
                 X 
                   
                   
                 X 
                 X 
                 0.70 
                 1.14 
               
               
                   
                 8 th   
                   
                 X 
                   
                 X 
                   
                 X 
                 0.61 
                 1.16 
               
               
                   
                 9 th   
                   
                 X 
                 X 
                   
                   
                 X 
                 0.51 
                 1.19 
               
               
                   
                   
               
             
          
         
       
     
         [0014]    Another example transmission is illustrated in  FIG. 2 . The transmission utilizes four simple planetary gear sets  80 ,  90 ,  40 , and  50 . Suggested numbers of gear teeth for each planetary gear set is listed in Table 3. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
             
             
               
                   
                 Ring 88/Sun 86 
                 2.05 
               
               
                   
                 Ring 98/Sun 96 
                 1.92 
               
               
                   
                 Ring 48/Sun 46 
                 1.89 
               
               
                   
                 Ring 58/Sun 56 
                 1.89 
               
               
                   
                   
               
             
          
         
       
     
         [0015]    Carrier  82  is fixedly coupled to ring gear  98 , ring gear  88  and carrier  92  are fixedly coupled to ring gear  58 , sun gear  46  is fixedly coupled to sun gear  56 , ring gear  48  is fixedly coupled to carrier  52 , and output shaft  12  is fixedly coupled to carrier  42 . Sun gear  86  is selectively held against rotation by brake  104  and selectively coupled to input shaft  10  by clutch  106 . Carrier  82  and ring gear  98  are selectively held against rotation by brake  102 . Input shaft  10  is selectively coupled to sun gear  96  by clutch  100  and selectively coupled to ring gear  48  and carrier  52  by clutch  62 . Sun gears  46  and  56  are selectively held against rotation by brake  60 . The combination of gear set  90  and clutch  100  selectively impose a speed relationship between ring gear  58 , carrier  82 , and input shaft  10 . Specifically, ring gear  58  is constrained to rotate at a speed between the speeds of input shaft  10  and carrier  82  whenever clutch  100  is engaged. 
         [0016]    As shown in Table 4, engaging the clutches and brakes in combinations of three establishes nine forward speed ratios and one reverse speed ratio between input shaft  10  and output shaft  12 . When the gear sets have tooth numbers as indicated in Table 3, the speed ratios have the values indicated in Table 4. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 60 
                 62 
                 106 
                 104 
                 100 
                 102 
                 Ratio 
                 Step 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Rev 
                 X 
                   
                 X 
                   
                   
                 X 
                 −4.79 
                 70% 
               
               
                 1 st   
                 X 
                   
                   
                   
                 X 
                 X 
                 6.84 
               
               
                 2 nd   
                 X 
                   
                   
                 X 
                 X 
                   
                 3.82 
                 1.79 
               
               
                 3 rd   
                 X 
                   
                 X 
                   
                 X 
                   
                 2.34 
                 1.63 
               
               
                 4 th   
                 X 
                 X 
                   
                   
                 (X) 
                   
                 1.53 
                 1.53 
               
               
                 5 th   
                   
                 X 
                 X 
                   
                 X 
                   
                 1.00 
                 1.53 
               
               
                 6 th   
                   
                 X 
                   
                 X 
                 X 
                   
                 0.80 
                 1.25 
               
               
                 7 th   
                   
                 X 
                   
                   
                 X 
                 X 
                 0.70 
                 1.14 
               
               
                 8 th   
                   
                 X 
                   
                 X 
                   
                 X 
                 0.61 
                 1.16 
               
               
                 9 th   
                   
                 X 
                 X 
                   
                   
                 X 
                 0.51 
                 1.19 
               
               
                   
               
             
          
         
       
     
         [0017]    A third example transmission is illustrated in  FIG. 3 . The transmission utilizes four simple planetary gear sets  110 ,  120 ,  40 , and  50 . Suggested numbers of gear teeth for each planetary gear set is listed in Table 5. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 5 
               
               
                   
                   
               
             
             
               
                   
                 Ring 88/Sun 86 
                 1.50 
               
               
                   
                 Ring 98/Sun 96 
                 1.92 
               
               
                   
                 Ring 48/Sun 46 
                 1.89 
               
               
                   
                 Ring 58/Sun 56 
                 1.89 
               
               
                   
                   
               
             
          
         
       
     
         [0018]    Carrier  112  is fixedly coupled to ring gear  128 , sun gear  116  is fixedly coupled to sun gear  126 , carrier  122  is fixedly coupled to ring gear  58 , sun gear  46  is fixedly coupled to sun gear  56 , ring gear  48  is fixedly coupled to carrier  52 , and output shaft  12  is fixedly coupled to carrier  42 . Ring gear  118  is selectively held against rotation by brake  134  and selectively coupled to input shaft  10  by clutch  136 . Carrier  112  and ring gear  128  are selectively held against rotation by brake  132 . Input shaft  10  is selectively coupled to sun gears  116  and  126  by clutch  130  and selectively coupled to ring gear  48  and carrier  52  by clutch  62 . Sun gears  46  and  56  are selectively held against rotation by brake  60 . 
         [0019]    As shown in Table 6, engaging the clutches and brakes in combinations of three establishes nine forward speed ratios and one reverse speed ratio between input shaft  10  and output shaft  12 . When the gear sets have tooth numbers as indicated in Table 5, the speed ratios have the values indicated in Table 6. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 6 
               
               
                   
                   
               
               
                   
                 60 
                 62 
                 106 
                 104 
                 100 
                 102 
                 Ratio 
                 Step 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Rev 
                 X 
                   
                 X 
                   
                   
                 X 
                 −4.56 
                 67% 
               
               
                 1 st   
                 X 
                   
                   
                   
                 X 
                 X 
                 6.84 
               
               
                 2 nd   
                 X 
                   
                   
                 X 
                 X 
                   
                 3.87 
                 1.77 
               
               
                 3 rd   
                 X 
                   
                 X 
                   
                 X 
                   
                 2.34 
                 1.65 
               
               
                 4 th   
                 X 
                 X 
                   
                   
                 (X) 
                   
                 1.53 
                 1.53 
               
               
                 5 th   
                   
                 X 
                 X 
                   
                 X 
                   
                 1.00 
                 1.53 
               
               
                 6 th   
                   
                 X 
                   
                 X 
                 X 
                   
                 0.80 
                 1.26 
               
               
                 7 th   
                   
                 X 
                   
                   
                 X 
                 X 
                 0.70 
                 1.14 
               
               
                 8 th   
                   
                 X 
                   
                 X 
                   
                 X 
                 0.61 
                 1.16 
               
               
                 9 th   
                   
                 X 
                 X 
                   
                   
                 X 
                 0.51 
                 1.20 
               
               
                   
               
             
          
         
       
     
         [0020]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and can be desirable for particular applications.