Abstract:
A continuously variable transmission that is highly suitable for use in a large car or light truck vehicle is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/842,749, filed Sep. 7, 2006. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to continuously variable transmissions, especially continuously variable transmissions used in large car and light truck vehicles. 
     BACKGROUND OF THE INVENTION 
     Continuously variable transmissions can be found in a review of U.S. Pat. Nos. 6,997,838, 6,530,855 and U.S. Patent Publication No. 2003/0166430. 
     SUMMARY OF THE INVENTION 
     The present invention provides a continuously variable transmission that is highly suitable for use in a large car or light truck vehicle that is an alternative to the continuously variable transmissions cited above. In one embodiment, the transmission includes an input shaft torsionally associated with a carrier, the carrier having at least first and second sets of pinion gears rotatably mounted thereon. A fluid pump is also provided that is torsionally associated via a gear train with the first and second pinion gears. A fluid motor powered by the pump is provided. An output shaft is torsionally associated with the motor and independently torsionally associated with the carrier is also included. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic view of an embodiment of the present invention; 
         FIG. 1B  is a partial schematic front view of the transmission shown in  FIG. 1A ; 
         FIG. 1C  is a partial schematic side view of the transmission shown in  FIG. 1A ; 
         FIG. 2  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 3A  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 3B  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 4  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 5  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 6  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 7  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 8  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 9  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 10  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 11  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 12  is a schematic view of an alternate embodiment of the present invention; 
         FIG. 13  is a schematic view of an alternate embodiment of the present invention; and 
         FIG. 14  is a schematic view of an alternate embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1A-1C , transmission  7  of the present invention has an input shaft  10  connected with the output of a power source such as an engine or motor. The input shaft  10  is connected with a clutch  14 . The clutch  14  is connected with an intermediate shaft  16 . The shaft  16  is connected with a front or first ring gear  18 . The ring gear  18  has internal teeth mating with a first pinion gear set  20 . The pinion gears  20  rotate on shafts  22 . The pinion gears  20  are additionally in mesh with a second pinion gear set  24 . The pinion gears  24  rotate on shafts  26 . Pinion gears  24  are positioned radially outward from pinion gears  20  (see  FIG. 1B ). Shafts  22  and  26  are connected on a common front or first carrier  30 . The pinion gears  20 ,  24  and the carrier  30  form a torque distributor that is torsionally associated with the input and output shafts  16 ,  70  and with a pump  46  in a manner to be described later. The pinion gears  24  are in mesh with a sun gear  32 . The sun gear  32  is fixed with a ring gear  34 . The ring gear  34  meshes with the pinion gear set  36 . Pinions  36  rotate about shafts  38 . The shafts  38  are connected with a second carrier  40 . The second carrier  40  is connected with a chain sprocket  42 . The chain sprocket  42  is torsionally connected via a chain (not shown) with the chain sprocket  44 . 
     Sprocket  44  is connected with the fluid pump  46 . The sun gear  32 , ring gear  34 , pinion gear  36 , carrier  38  and sprockets  42 ,  44  create a gear chain that connects the torque distribution with the pump  46 . In an alternate embodiment, the carrier  40  can be torsionally connected by meshing gears with the pump  46 . A motor  48  is connected with a sprocket  50 . The pump  46  is a variable positive displacement hydrostatic pump. The pump  46  is fluidly connected with the variable positive displacement hydrostatic motor  48 . The sprocket  50  via a chain (not shown) is connected with a sprocket  52 . The sprocket  52  is fixably connected with a ring gear  54 . In an alternate embodiment, the motor  48  can be torsionally connected by meshing gears with the ring gear  54 . 
     Pinions  36  mesh with a middle or second sun gear  56 . The sun gear  56  is connected with a shaft  58  that is fixed with a clutch plate  60  and third sun gear  62 . The sun gear  62  meshes with a fourth pinion gear set  64 . The pinion gears  64  additionally mesh with the ring gear  54 . The pinion gears  64  rotate about shafts  66 . The shafts  66  are fixed with a rear or third carrier  68 . The first carrier  30  and the third carrier  68  are fixed with the output shaft  70 . A selectively engageable clutch brake  72  is provided to optionally ground the sun gears  56  and  62  via the clutch plate  60 . 
     A controller  74  controls the operation of transmission  7 . Controller  74  can be a separate controller, a portion of the engine controller, or a confederation of different controllers within the vehicle. Controller  74  is cognizant of the selected gear by a gear selector, engine throttle position, engine speed, output speed of the transmission, and various operational parameters of a hydraulic pump  46 , and the hydraulic motor  48 . 
     In operation, input torque from an engine or other power source is delivered to the ring gear  18  and is then divided into two paths by the torque distributor. The first path is to the carrier  30  and the output shaft  70 . The second path is to the sun gear  32  to the pump  46 , motor  48  and then to the output shaft  70 . The displacement of the pump  46  and the motor  48  are variable. The controller, by setting pump and motor displacements, defines a displacement ratio. Due to incompressible nature of hydraulics, the displacement ratio pump/motor determines the speed ratio of the pump/motor. The controller thereby affects the speeds of each torque path (sun gear  32  and carrier  30 /output shaft  70 ), and sets the overall transmission ratio and power split. 
     In the example shown in  FIG. 1C , the torque distributor ring gear  18  radius is 82 mm. The sun gear  32  radius is 41 mm. The pinions  20  and  24  have a 32.5 mm radius. The maximum engine output speed is approximately 6000 rpm. Torque multiplication in drive mode is approximately 0.5 to 8.0:1. Torque multiplication in reverse mode is approximately 1.5 to 6.0:1. Speed multiplication in drive mode is approximately 0.02 to 2.0:1. Speed multiplication in reverse mode is approximately 0.02 to 0.5:1. 
     The later described transmissions all have a controller  74  as described for the transmission  7 . 
     Referring to  FIG. 2 , a transmission  8  is provided which is identical in functioning as the transmission  7  except with a deletion of an input clutch. 
     Referring to  FIG. 3A , transmission  107 A provides an alternative preferred embodiment of the present invention wherein the sun gear  32  is connected torsionally with the output shaft  70  instead of the pump  46 . The carrier  30  is directly connected (via gear train sprockets  42 ,  44 ) with the pump  46 . The clutch brake  72  is provided after the motor  48  instead of between the motor  46  and the pump  48 . 
     Referring to  FIG. 3B , transmission  107 B schematically illustrates an alternative embodiment of transmission  107 A wherein the shafts  22 A,  26 A of the pinion gears  20  and  24  are extending in opposite directions to one another and the first carrier  30 A is shortened in length. 
     Referring to  FIG. 4 , transmission  117  is similar to the transmission  107  except that the sun gear  32  is connected with the pump  46  instead of the output shaft  70 . The first carrier  30  is connected with the output shaft  70  instead of the pump  46 . 
     Referring to  FIG. 5 , transmission  127  is similar to transmission  7  except for the omission of clutch  14  and the replacement of the clutch brake  72  with a clutch  61 . 
     Referring to  FIG. 6 , transmission  137  is similar to transmission  7  except that sun gear  56  drives the pump  46 , and carrier  40  is connected to sun gear  62 . The clutch brake  72  is also deleted. Additionally the second sun gear  56  is connected directly via the sprocket  42  and  44  with the pump  46 . In addition, there is a clutch  63  between the sun gear  32  and the second ring gear  34 . 
     Referring to  FIG. 7 , transmission  147  is similar to transmission  137  with significant changes. The second carrier  40  supports two inter-meshing pinions  21  and  25 . The sun gear  32  via the clutch  63  is torsionally connected with the ring gear  34 . The second sun gear  56  is connected with the pump  46 . The second carrier  40  via the sun gear  62 , pinion  64  and carrier  68  is connected with the output shaft  70 . In a manner, similar to transmission  137 , the first carrier  30  is connected with the output shaft  70 . 
     Referring to  FIG. 8 , transmission  157  is similar to transmission  147  with the exception that the first carrier  30  only has a single pinion gear set  23 . Accordingly the input shaft  16  is connected to the torque distributor of the transmission  157  (carrier  40 , and pinions gears  21 ,  25 ) via a pre torque distributor planetary gear set (gear  18 , carrier  30 , pinion  23  and sun gear  32 ). Additionally the torque distributor is torsionally associated with the output shaft  70  via sun gear  62 , pinions  64 , and the carrier  68 . 
     Referring to  FIG. 9 , transmission  167  is similar to transmission  7  but having a smaller diameter sun gear  18 A. The sun gear  18 A connects the torque distributor to the input shaft  16 . 
     Referring to  FIG. 10 , transmission  177  is similar to transmission  7  but having pinion shafts  22  and  26 A extending in opposite directions and wherein the pinions  24  mesh with an inner diameter of a first ring gear  33 . 
     Referring to  FIG. 11 , transmission  187  is similar to transmission  7  except that the sun gear  32  is directly connected (via sprockets) with the pump  46  and the middle sun gear  56  is eliminated. 
     Referring to  FIG. 12 , transmission  207  is similar to transmission  7 A with a major change that the first and second pinion gears  27  and  29  rotate about a common axis and are rotatably connected (torsionally fixed) pinion gears. Additionally, the input shaft  16  is connected with an input sun gear  18 A. 
     Referring to  FIG. 13 , transmission  217  is similar to transmission  207  being modified by an input clutch  14  and the elimination of the clutch brake  72 . Additionally the first sun gear  32  and second sun gear  56  are directly connected together. 
     Referring to  FIG. 14 , transmission  227  is similar to transmission to  217  with a modification of the first sun gear  32  being directly connected with the pump  46  (via sprockets). The transmission  227  is similar to the transmission  187  except that the pinion gear sets  29  and  27  of the first carrier  30  are on a common rotational axis. 
     While preferred embodiments of the present invention have been disclosed, it is to be understood it has been described by way of example only, and various modifications can be made without departing from the spirit and scope of the invention as it is encompassed in the following claims.