Abstract:
A fixed ratio traction drive is disclosed that uses multidiameter planet rollers. The high speed traction drive provides speed reduction from a high speed shaft. A planet carrier is used to rotationally mount the multidiameter rollers. A continuously variable transmission that uses planetary ball traction is also disclosed that provides infinitely variable speed ratios.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Mechanical coupling of various types of machine devices typically use gearing systems. Rotational mechanical energy can be transferred between machines in a manner that allows the rpm levels of the rotational mechanical energy to be adjusted. 
         [0002]    Gears, however, are limited to rotational speeds of approximately 100,000 rpm. In fact, highly polished and specially designed gears must be used to reach these high rotational speeds. High speed rotational devices that have rotational speeds of above 100,000 exist in numerous different environments. Hence, there is a need to couple these high rotational speeds to other machines and other devices at rotational speeds in which standard gearing systems can be used. 
       SUMMARY OF THE INVENTION 
       [0003]    An embodiment of the present invention may therefore comprise a traction drive comprising: a shaft having a central portion, the central portion having a shaft traction surface; a plurality of planetary rollers having a plurality of planetary roller traction surfaces that interface with the shaft traction surface so that a first plurality of traction interfaces exist between the plurality of planetary roller traction surfaces and the shaft traction surface; a ring roller that is rotated by the plurality of planet rollers through a second plurality of traction interfaces. 
         [0004]    An embodiment of the present invention may further comprise a method of transferring rotational mechanical energy between a shaft and a ring roller comprising: providing a shaft that has a central portion, the central portion having a shaft traction surface; placing a plurality of planet roller traction surfaces of a plurality of planet rollers in contact with the shaft traction surface so that a plurality of first traction interfaces are created between the plurality of planet roller traction surfaces and the shaft traction surface; placing a ring roller in contact with the plurality of planetary rollers so that a plurality of second traction interfaces are created between the plurality of planet rollers and the ring roller; mounting the plurality of planetary rollers on a planet carrier that rotates in a direction opposite to the ring roller. 
         [0005]    An embodiment of the present invention may further comprise a continuously variable traction drive comprising: a first race that is rotationally coupled to a shaft; a second race that is fixed with respect to the continuously variable traction drive; 
         [0000]    a third race that is rotationally coupled to the shaft and mounted in the continuously variable traction drive to allow lateral translation of the third race with respect to the first race and the second race; a fourth race that is rotationally coupled to a gear, the fourth race mounted in the continuously variable traction drive to allow lateral translation of the fourth race by an amount and in a direction that is substantially equal to the lateral translation of the third race; a plurality of traction ball bearings disposed between the first race, the second race, the third race and the fourth race. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an isometric view of an embodiment of a multidiameter traction drive. 
           [0007]      FIG. 2  is a side cutaway view of the multidiameter traction drive illustrated in  FIG. 1 . 
           [0008]      FIG. 3  is a top cutaway view of the multidiameter traction drive of  FIGS. 1 and 2 . 
           [0009]      FIGS. 4 and 5  are illustrations of an embodiment of a continuously variable traction transmission. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]      FIG. 1  is a perspective view of isolated key components of the multi-diameter traction drive  100 . As shown in  FIG. 1 , the shaft  104  can comprise various types of shafts that can be connected to various types of devices, such as flywheels, super-turbochargers, and various other types of high speed mechanical devices. Shaft  104  passes through the center of the multi-diameter traction drive  100 . The multi-diameter traction drive  100  includes multi-diameter planet rollers  664 ,  666  ( FIG. 3 ),  668 . These multi-diameter planet rollers are rotationally coupled to a planet carrier  124  ( FIGS. 2 and 3 ). Balls  114 ,  116 ,  118 ,  120  rest on an incline surface of ball ramps, such as ball ramps  121 ,  126 , on the fixed ring  112 . Ring roller  102  is driven by an inner diameter of the multi-diameter planet rollers  106 ,  108 ,  110 , as disclosed in more detail below. 
         [0011]      FIG. 2  is a side cutaway view of the multi-diameter traction drive  100 . As shown in  FIG. 2 , the shaft  104  is hardened and polished to form a traction surface that is used as a sun roller  136  that has a traction interface  128  with the multi-diameter planet roller  108 . The multi-diameter planet roller  108  rotates around the multi-diameter planet roller axis  134 . The multi-diameter planet roller  108  contacts the fixed ring  112  at the interface  132  of the planet roller  108  and the fixed ring  112 . The multi-diameter planet roller  108  contacts the ring roller  102  at interface  130 , which is a different radial distance from the multi-diameter planet roller axis  134 , than the interface  130 .  FIG. 2  also illustrates the planet carrier  124  ( FIG. 3 ) and the ball ramp  126  that intersects with the ball  118 . The balls  114 ,  116 ,  118 ,  120  are wedged in between a housing (not shown) and the ball ramps, such as ball ramps  212 ,  126 , on the fixed ring  112 . When torque is applied to the ring roller  102 , this causes the fixed ring  112  to move slightly in the direction of the rotation of the ring roller  102 . This causes the balls  114 - 120  to move up the various ball ramps, which, in turn, causes the fixed ring  112  to press against the multi-diameter planet rollers  106 ,  108 ,  110 . Since the interface  130  of the planet roller  108  and ring roller  102  is sloped, and the interface  132  of the planet roller  108  and fixed ring  112  is sloped, an inward force on the multi-diameter planet roller  108  is generated, which generates a force on the traction interface  128  to increase the traction at the traction interface  128  between the multi-diameter planet roller  108  and the sun roller  136 . In addition, a force is created at the interface  130  of the multi-diameter planet roller  108  and the ring roller  102 , which increases traction at interface  130 . Ring roller  102  is coupled to the transfer gear  122 , as also shown in  FIG. 2 . 
         [0012]      FIG. 3  is a side cutaway view of the multi-diameter traction drive  100 . As shown in  FIG. 3 , the sun roller  136  rotates in a clockwise direction, as shown by rotation direction  142 . The multi-diameter planet rollers  106 ,  108 ,  110  have outer diameter roller surfaces, such as outer diameter roller surface  140  of multi-diameter planet roller  108 . These outer diameter roller surfaces contact the sun roller  136  which cause the multi-diameter planet rollers  106 ,  108 ,  110  to rotate in a counter-clockwise direction, such as rotational direction  144  of multi-diameter planet roller  110 . The multi-diameter planet rollers  106 ,  108 ,  110  also have an inner diameter roller surface, such as inner roller diameter roller surface  138  of multi-diameter planet roller  108 . The inner diameter roller surface of each multi-diameter planet roller contacts the roller surface  138  of the ring roller  102 . Hence, the interface  130  of planet roller  108  with the roller surface  138  of ring roller  102  constitutes a traction interface that transfers rotational mechanical energy when a traction fluid is applied. The interface between each of the multi-diameter planet rollers  106 ,  108 ,  110  on the sun roller  136  also constitutes a traction interface that transfers rotational mechanical energy upon application of a traction fluid. 
         [0013]    As indicated above with respect to  FIGS. 2 and 3 , the fixed ring  112  generates a force, which pushes the multi-diameter planet rollers  106 ,  108 ,  110  towards the sun roller  136  to generate traction. Each of the multi-diameter planet rollers  106 ,  108 ,  110  is rotationally attached to the planet carrier  124  with planet roller axes, such as the multi-diameter planet roller axis  134  of the multi-diameter planet roller  108 . These axes have a slight amount of play so that the multi-diameter planet rollers  106 ,  108 ,  110  can move slightly and create a force between the sun roller  136  and the outer diameter of the roller surface of the multi-diameter planet rollers  106 ,  108 ,  110 , such as the outer diameter roller surface  140  of the planet roller  108 . The movement of the multi-diameter planet roller  108  towards the sun roller  136  also increases the traction at the interface of the multi-diameter planet rollers  106 ,  108 ,  110  and the ring roller  102 , since the interface between the multi-diameter planet rollers  106 ,  108 ,  110  and the ring roller  102 , such as interface  130 , is sloped. The contact of the multi-diameter planet rollers  106 ,  108 ,  110  with the roller surface  138  of ring roller  102  causes the planet carrier  124  to rotate in a clockwise direction, such as the rotational direction  140 , illustrated in  FIG. 3 . As a result, the ring roller  102  rotates in a counter-clockwise direction, such as rotational direction  144 , and drives the transfer gear  122  in a clockwise direction. 
         [0014]      FIGS. 4 and 5  illustrate an example of a continuously variable traction drive  400 . The continuously variable traction drive illustrated in  FIGS. 4 and 5  operates by translating races  416 ,  418  in a lateral direction on race surfaces that have a radius of curvature that causes contact locations of the ball bearings to move, which, in turn, causes the balls to rotate with a different spin angle to drive race  422  at different speeds. In other words, the contact location of each of the bearings on the race surfaces is changed as a result of the lateral translation of the races  416 ,  418 , which alters the speed at which the bearings are rotating at the contact location, as explained in more detail below. 
         [0015]    Input torque from a source such as a super-turbocharger, an engine, or other source, is used to drive the spline input gear  404  of the input shaft  402 . The input torque on the spline input gear  404  imparts a spin in rotational direction  412  on both the input shaft  402  and its associated structure including input race  414 . Input race  416  is also spun around the axis of rotation  406  in response to the torque imparted by spline  466  from the input shaft  402  to the input race  416 . The rotation of the input shaft  402 , input race  414  and input race  416  impart a spin on the plurality of ball bearings  432  because the stationary race  420  impedes the rotation of the ball bearings at the contact point with stationary race  420 . Input race  414  and input race  416  rotate at the same angular speed since they are coupled together through spline  466 . Input race  414  and input race  416  cause the ball bearings  432  to spin in a substantially vertical orientation since the ball bearings  432  contact the stationary race  420 . The contact of the ball bearings  432  against the stationary race  420  also causes the ball bearings  432  to precess around the perimeter of the races  414 ,  416 ,  418 ,  420 . In the embodiment illustrated in  FIG. 4 , there may be as many as 20 ball bearings  432  that rotate on the surfaces of the races  414 ,  416 ,  418 ,  420 . The rotation of the ball bearings  432  as a result of being driven by input race  414  and input race  416  creates a tangential contact of the ball bearings  432  on the output race  418 . Depending upon the contact position of the ball bearings  432  on the output race  418 , the ratio of the rotational speed of the input races  414 ,  416  with respect to the output race  418  can be varied. Output race  418  is coupled to output gear  422 . Output gear  422  engages output gear  424 , which in turn is connected to the output shaft  426 . 
         [0016]    The manner in which the traction drive continuously variable transmission  400 , illustrated in  FIG. 4 , shifts the ratio between the input shaft  402  and the output shaft  426  is accomplished by changing the relative position of the contact point between the four races  414 ,  416 ,  418 ,  420  that are in contact with the ball bearings  432 . The manner in which the contact surfaces of the races  414 ,  416 ,  418 ,  420  with the ball bearings  432  is changed is by shifting the position of the translating clamp  452 . The translating clamp  452  is moved horizontally, as illustrated in  FIG. 4 , in response to electric actuator  462 . Electric actuator  462  has a shaft that engages the telescopic shifter  458  and rotates the telescopic shifter  458 . Telescopic shifter  458  has different thread types on an inside portion and an outside portion. A difference in thread pitch of the different thread types causes the translating clamp  452  to translate horizontally in response to rotation of the shaft of the electric actuator  462 , which imparts rotation in the telescopic shifter  458 . Lateral translation of the translating clamp  452 , which is in contact with bearing clamp  464 , causes lateral transition of input race  416  and output race  418 . Lateral translation of the input race  416  and output race  418  may vary, in the embodiment illustrated in  FIG. 4 , by approximately one-tenth of an inch. The translation of the input race  416  and the output race  418  changes the angle of contact between the ball bearings  432  and the output race  418 , which changes the ratio, or speed at which the ball bearings  432  are moving in the races because of a change in contact angle between the stationary race  420  and input race  414  and input race  416 . The combination of the change in angle between the races allows the contact velocity, or the point of contact between the ball bearings  432  and output race  418 , to vary which results in a variation of speed of between 0 percent of the rotational speed of the input shaft  402  up to 30 percent of the rotational speed of the input shaft  402 . The variation of speed in the output race  418  of 0 percent to 30 percent of the rotational speed of the input shaft  402  provides a wide range of adjustable rotational speeds that can be achieved at the output shaft  426 . 
         [0017]    To ensure proper clamping of the ball bearings  432  between the races  414 ,  416 ,  418 ,  420 , springs  454 ,  456  are provided. Spring  454  generates a clamping force between input race  414  and stationary race  420 . Spring  456  generates a clamping force between input race  416  and output race  418 . These clamping forces against the ball bearings  432  are maintained over the entire translating distance of the translating clamp  452 . The telescopic shifter  458  has threads on an inside surface that connect to the threads on the fixed threaded device  460 . The fixed threaded device  460  is fixed to housing  472  and provides a fixed position relative to the housing  472  so that the translating clamp  452  is able to translate in a horizontal direction as a result of the differential threads on the two sides of the telescopic shifter  458 . 
         [0018]    As also illustrated in  FIG. 4 , the rotating components of the traction drive continuously variable transmission  400  all rotate in the same direction, i.e. rotational direction  412  and output rotation  428  of the output gear  422 . Clamping nut  468  holds spring  456  in place and preloads the spring  456  to create the proper diagnonal pressure between stationary race  420  and input race  414 . When the translating clamp  452  is horizontally translated, as illustrated in  FIG. 4 , there is a slight translation of the input shaft  402  based upon the angles of the races  414 - 420  that contact the ball bearings  432 . The spline input gear  404  allows translational movement in directions  408 ,  410  based upon the points at which the ball bearings  432  contact the races  414 - 420  and the particular contact angle of the races with respect to the ball bearings  432 . Housing  470  is bolted tightly to housing  472  to contain the spring  454 , which creates the proper amount of clamping force between input race  414  and stationary race  420 . Ball bearings  432 , as illustrated in  FIG. 4 , have a rotational progression  431  in the four races  414 ,  416 ,  418 ,  420 . The rotational direction  412  of the shaft  402  causes the gear  422  to rotate in a rotational direction  428 , as illustrated in  FIG. 4 . 
         [0019]      FIG. 5  is a closeup view of the races  414 - 420  and ball  432 , illustrating the operation of the traction drive continuously variable transmission  400 . As shown in  FIG. 5 , race  414  forcibly contacts ball  432  at contact location  434 . Race  416  forcibly contacts ball  432  at contact location  436 . Race  418  forcibly contacts ball  432  at contact location  438 . Race  420  forcibly contacts ball  432  at contact location  440 . Each of the contact locations  434 ,  436 ,  438 ,  440  is located on a common great circle on the surface of the ball  432 . The great circle is located in a plane that contains the center of the ball  432  and the axis  406  of the shaft  402 . Ball  432  spins about a spin axis  442  passing through the center of the ball  432  and bisects the great circle containing contact locations  434 ,  436 ,  438 ,  440 . The spin axis  442  of the ball  432  is inclined at an angle  446  with the vertical axis  444 . The inclination angle  446  is the same for each of the balls disposed in the races around the circumference of the traction drive  400 . The inclination angle  446  establishes a mathematical relationship between a distance ratio and a circumferential velocity ratio. The distance ratio is the ratio between the first distance  448 , which is the orthogonal distance from the spin axis  442  to the contact location  434 , and a second distance  450 , which is the orthogonal distance from the spin axis  442  to contact location  436 . This distance ratio is equal to the circumferential velocity ratio. The circumferential velocity ratio is the ratio between the first circumferential velocity and the second circumferential velocity, where the first circumferential velocity is the difference between the circumferential velocity of ball  432  at race  414  and a common orbital circumferential velocity of ball  432  and the other balls in the races, while the second circumferential velocity is the difference between the circumferential velocity of the ball  432  on the race  416  and the common orbital circumferential velocity of the ball  432 , as well as the other balls disposed in the races. The radius of curvature of each of the races  414 - 420  is larger than the radius of curvature of ball  432 . In addition, the radius of curvature of each of the races  414 - 420  need not be a constant radius of curvature, but can vary. Further, the radius of curvature of each of the four races does not have to be equal. 
         [0020]    When races  416 ,  418  translate simultaneously in a lateral direction, such as lateral translation direction  408 , the speed ratio of the rotation of shaft  402  and the rotational direction  412  change with respect to the rotation of the gear  422  and rotational direction  428 . Translation of races  416 ,  418  in lateral translation direction  408  causes the first distance  448  to be larger and the second distance  450  to be smaller. Hence, the ratio of distances, as well as the circumferential velocity ratio, changes, which changes the rotational speed of the gear  422  with respect to shaft  402 . 
         [0021]    The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.