Abstract:
A continuously variable transmission is disclosed to change an input rotational velocity along a continuous spectrum using an eccentrically positioned cam cooperating with a counterweight assembly to counteract the imbalance generated by the eccentric cam. A plurality of cam followers in contact with the cam actuate crankshafts that drive planetary gears disposed about the crankshaft and cooperate with overrunning clutches. The overrunning clutch with the highest instantaneous velocity drives a sun gear connected to an output shaft. The velocity of the output shaft is governed by the eccentricity of the cam.

Description:
CROSS-REFERENCE TO RELATED PATENT  
       [0001]    This application is a divisional of application Ser. No.  09 / 664 , 263  filed Sep. 10, 2000 for Continuously Variable Transmission, now U.S. Pat. No. 6,425,301 B1 granted Jul. 30, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The invention is directed to the field of continuously variable transmissions.  
           [0004]    2. Description of Related Art  
           [0005]    Variable transmissions are known in the art for converting an input torque and velocity to an output torque and velocity over a wide range of input-to-output ratios. In a continuously variable transmission, there is a smooth transition from input to output over a spectrum of ratios, as opposed to discrete incremental ratios as with conventional transmissions. Examples of infinitely variable transmissions include the Letters Patent to Pires, U.S. Pat. No. 5,334,115; the Letters Patent to Mercat, U.S. Pat. No. 5,081,877; the Letters Patent to Genovese, U.S. Pat. No. 5,071,393; and the Letters Patent to Coronel, U.S. Pat. No. 5,352,162.  
           [0006]    The Pires patent describes a variable transmission relying on an oscillating 15 ratchet. Pires teaches a plurality of different successive intermediate rotations that vary in velocity and direction in accordance with their own respective oscillatory wave form, each waveform being out of phase with one another in a predetermined way. These intermediate rotations are used to convert the rotational input to a plurality of uni-directional output rotations, without the use of over-running clutches. The outputs vary in velocity in accordance with their own respective waveforms and are used to produce a modified rotational output.  
           [0007]    The Genovese patent purports to show a variable ratio transmission with a stationary housing having a variable diameter internal surface and an input and output shaft journalled in the housing for rotation abut a common axis co-axial with the variable diameter internal surface of the housing. A floating eccentric mounted on the input shaft has an external cylindrical surface with the eccentricity of that cylindrical surface with respect to the input shaft being variable between approximately co-axially with the input shaft to a maximum preset eccentricity. A drive member supported co-axially on the floating eccentric has an external cylindrical surface in rolling engagement with the internal of the variable diameter internal surface and coupled to the output shaft. The rotational velocity ratio of the Genovese device between the input and output shaft is varied by varying the diameter of the internal cylindrical surface of the housing and correspondingly varying the degree of eccentricity of the floating eccentric to the input shaft.  
           [0008]    The Mercat patent discloses a variable transmission in which a driving element and a driven element are adjustable eccentrically to one another and are coupled via pivotal levers which are journalled on one element and can be brought into force transmitting clamping engagement with the other element via coupling shoes. The two change velocity units are inversely combined with an eccentric positioning device which either jointly actuates the members with the ring tracks associated with the coupling elements or the members with the coupling elements. The force transmitting zones of engagement of the two units are angularly displaced relative to one another and the eccentricities of the two units and also the lever arms associated with the coupling elements can be so selected that transmission ratios result which are free of fluctuations.  
           [0009]    The Coronel patent discloses a dual concentric positively infinitely variable transmission which uses a user actuated control to vary the transmission output. The input control varies the orbital relationship and effective gear ratio between a driving ring gear and a driven pinion gear causing both gears to variably orbit the mechanism central axis to produce an output receiving gear and connected output shaft torque converting velocity range, where the velocity varies between a geared neutral stopped position and its maximum output velocity.  
           [0010]    The aforementioned devices are complicated, cumbersome transmissions which are difficult to control and were limited to low horsepower. The design of the present invention is to overcome the shortcomings of the prior art of continuously variable transmissions by teaching a simple, compact design having more versatility than previous transmissions.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0011]    The present invention can be used to increase or decrease an input rotational velocity along a continuous spectrum using an eccentric cam and a plurality of overrunning clutches. In a first embodiment, a cam plate with an annulus can be pivoted from a concentric to an eccentric position. A plurality of planet gears have crankshafts which are actuated when the cam plate is pivoted in an eccentric position, but are not actuated when the cam plate is in the concentric position. The crankshafts rotate through an angle on their own axis at different speeds, depending on the cam plate eccentricity, as the carrier rotates during a cycle. Each crankshaft drives a one-way overrunning clutch which rotates the planet gears, which drive a sun gear engaged with the planet gears. The sun gear is driven at a minimum by an input velocity by the carrier, and is augmented by the planet gear with the highest rotational speed. The remaining planet gears are then driven by the sun gear as the overrunning clutches relinquish control to the fastest rotating planet gear. The ratio of the output velocity to the input velocity is controlled by the amount of eccentricity of the cam plate, and the spectrum of ratios is continuous over a range.  
           [0012]    In a second embodiment, an input velocity drives a cam bearing at input velocity, and the cam bearing can be pivoted from a concentric position to an eccentric position. In the concentric position, crankshafts actuated by an orbiting of said cam plate bearing are not actuated when said cam bearing is in a concentric position, and unlike the previous embodiment the sun gear is not driven at input velocity, resulting in a zero velocity output. However, as the cam bearing is pivoted into an eccentric position, the crankshafts are actuated serially as the cam bearing orbits, and each crankshaft imparts a rotation to its associated planet gear. Each rotation of a planet gear in turn rotates the sun gear which drives the output velocity. The ratio of the output velocity to the input velocity varies between zero and one for this latter embodiment. In a third embodiment, the transmission of the second embodiment is actuated with an actuator rod which drives the cam bearing from a concentric position to an eccentric position.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The exact nature of this invention, as well as its objects and advantages, will become readily apparent upon reference to the following detailed description when considered in conjunction with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof and wherein:  
         [0014]    [0014]FIG. 1 is an exploded perspective view of one embodiment of the present invention;  
         [0015]    [0015]FIG. 2 is an exploded perspective view of a second embodiment of the present invention;  
         [0016]    [0016]FIG. 3 is an exploded perspective view of a third embodiment of the present invention; and  
         [0017]    [0017]FIG. 4 is a perspective view of the embodiment shown in FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor for carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the general principles of the present invention have been defined herein specifically to provide a continuously variable transmission.  
         [0019]    [0019]FIG. 1 illustrates a first embodiment of the present invention, in which an input rotational velocity transmitted by an input shaft is converted to an output rotational velocity via an output shaft, where the rotational velocity of the output shaft is equal to or greater than the rotational velocity of the input shaft. The transmission assembly comprises a housing  1  and mating end cap  2  joined by a plurality bolts  50  sized for tapped holes  51 . The housing has a centerline longitudinal axis on which the input shaft  20  and output shaft  14  is located. The input shaft  20  is journalled on a first bearing  10 , and the carrier  6  to which the input shaft is keyed is further is supported and jounralled by a second bearing  15 . Input shaft  20  rotates within these bearings and is driven by some prime mover (not shown) at an “input velocity.” 
         [0020]    Within the housing  1 , the input shaft  20  engages with a carrier  6  via a key  11  which fits in a slot  77  on the input shaft  20  and also in a slot in carrier  6 , such that the carrier  6  rotates within the housing  1  and with the input shaft  20  in a fixed relationship at the input velocity. The carrier  6  supports a plurality of planetary gears  9  each mounted on one-way, that the sun gear  22  rotates with the velocity of the planetary gears  9  in engagement therewith. The output shaft  14  for the transmission assembly is fixed with the sun gear  22  and rotates with a velocity equal to the sun gear  22 . The output shaft  14  and sun gear are supported and journalled on bearings  21  and  13 .  
         [0021]    Mounted within each planet gear assembly is a crankshaft  25  journalled on bearings  23 , where the crankshaft comprises a crankshaft head  26  and a crankshaft shaft  24 . The shaft  24  of the crankshaft  25  rotates within the planet gear  9  and is governed by a one-way, overrunning clutch  7  such that: (a) a rotation of the crankshaft  25  in the preferred direction will rotate the planet gear  9  in the same direction at the same speed; and (b) the overrunning clutch  7  allows the planet gear  9  to rotate faster than the crankshaft  25  if another external force is present.  
         [0022]    A cam plate  3  within the housing  1  is pinned by pivot pin  12  which allows the cam plate  3  to move in an arced path defined by said pivot pin  12 . The cam plate  3  has an eccentric opening  78  through which the input shaft  20  passes, and the shape of the eccentric opening  78  is such that the cam plate  3  always clears and does not contract the input shaft  20  as the cam plate  3  undergoes its full range of motion pivoting about the pivot pin  12 . The cam plate  3  can be pivoted by an actuator  18  which may operate pneumatically, hydraulically, electrically, or mechanically. The cam plate  3  further includes an annulus  31  which forms a circular track, and within the annulus  31  is a plurality of shoes  4  each corresponding to one of the plurality of crankshafts  25 . Note that rolling element bearings can be used in place of the shoes.  
         [0023]    The head  26  of each crankshaft  25  is provided with a pin  17 , where a force applied to the pin  17  produces a rotation of the crankshaft  25  in the direction of said force. Each pin  17  from the crankshaft  25  mates with a hole  29  on an opposed surface of said shoe  4  connecting each crankshaft  25  to a shoe  4  in said annulus  31  of said cam plate  3 . The individual crankshafts  25  are thus locked into the circular track formed by said annulus  31 .  
         [0024]    We begin with the situation in which the cam plate  3  is at a position of zero eccentricity, i.e. the annulus  31  is concentric with the input shaft  20 . If the input shaft  20  is imparted with an initial input velocity, the input velocity will be communicated to the carrier  6  and the carrier  6  will rotate with the given input velocity. At zero eccentricity, the crankshafts  25  are all aligned with the annulus  31  as the carrier  6  rotates, and there is no relative motion among the plurality of crankshafts  25 . Moreover, the crankshaft heads  26  follow the circular track of the annulus  31  without rotating because the concentricity ensures that the relative position of the crankshaft head  26  to the pinned shoe  4  does not change over time. Because the one-way clutches  7  of the planet gears  9  are engaged, the planet gears  9  are locked relative to the carrier  6  and thus rotate only with the same given input velocity as the carrier  6 . Thus, the crankshafts  25  all rotate in a fixed formation with the carrier  6  and cause the connected shoes  4  to rotate within the annulus  31  at the same rotational velocity as the input shaft  20 . Moreover, the planet gears  9  are all in contact with and drive the sun gear  22  at the same input velocity, which in turn results in the output shaft  14  being driven at the same velocity as the input shaft  20 .  
         [0025]    Turning now to the situation in which the actuator  18  causes the cam plate  3  to pivot about pivot pin  12 , resulting in an eccentricity of the annulus  31  with respect to the input shaft  20 . In this case, the input shaft  20  and carrier  6  continue to rotate at input velocity. The carrier  6  still drives the planet gears  9 , but now there is a relative motion among each crank shaft  25  due to each crank shaft&#39;s relationship between its pinned point at the shoe  4  and the eccentric location of that shoe  4  with respect to the other shoes  4 . This relative motion will cause each shaft  24  of the crankshafts  25  to rotate about its own axis at a different speed than the other shafts based on the eccentricity of the driven shoe  4 . That is, each crankshaft head  26  has a tangential force applied at the pin  17  due to the eccentricity of the cam plate annulus  31  with respect to the axis of rotation of the plurality of crankshafts  
         [0026]    This tangential force causes each crankshaft  25  to rotate, and the speed of each crankshaft rotation is governed by the position of the shoe  4  within the annulus  31  and the amount of eccentricity applied.  
         [0027]    Each planet gear  9  would rotate with a different velocity (the initial input velocity plus an incremental velocity due to the added rotation of the crankshaft), but for the over-running clutch  7  which permits a greater rotation than that of the crankshaft  25 . The fastest turning planet gear  9  drives the sun gear  22 , which in turn drives the remaining planet gears  9 . The only clutch engaging its corresponding crankshaft is the one on the shaft  24  of the crankshaft  25  having the highest rotation speed. The other planet gears will overrun on their one-way clutches  7  due to the lower rotational velocity of their respective crankshaft shaft  24 . As the carrier  6 , planet gears  9 , crankshafts  25 , and shoes  4  are rotating each crankshaft  25  in turn will have the maximum rotational velocity as the shoes  4  rotate in the cam plate annulus  31 . Thus, each crankshaft  25  engages its planetary gear&#39;s one-way clutch  7  during part of a cycle and in turn imparts an additional rotation to the output shaft  14 . This additional rotational velocity augments the input velocity and ensures that the output velocity will be greater than the input velocity. As the eccentricity increases, the relative motion between the various crankshafts increases and the additional rotational velocity that will be imparted on one of the crankshafts  25  increases, which in turn will be applied to the output shaft  14 . However, the transition from one input-to-output ratio to another occurs over a continuous spectrum as the plurality of one-way clutches  7  “hands-off” the highest rotating crankshaft from one to another, with the slower running crankshafts  25  being overrun by the fastest rotating crankshaft  25 .  
         [0028]    The summing of the intermittent crankshaft rotations can be varied from the given configuration by modifying the transmission without deviating from the same principle. For example, rather than having the sun gear rotate and the housing remain fixed, the relationship could be reversed such that the housing rotated and the sun gear could be stationary.  
         [0029]    The aforementioned embodiment demonstrates a transmission in which the ratio of the input to output rotational velocity is on the order of 1:1 to 1:3, although higher or lower maximum velocities are possibly by modifying the components. In a second embodiment illustrated in FIG. 2, the ratio of the input to output rotational velocity has a range from 1:1 to zero. In this embodiment of the invention, there is no carrier such as the one in FIG. 1 which was driven at input velocity and which assured that the output velocity would be at least equal to the input velocity.  
         [0030]    In FIG. 2, bearing  105  is mounted in housing  106  and input shaft  103  drives the drive shaft  111  which is supported by bearings  105  and  112 . Pivotally mounted to the drive shaft  111  at pin  107  is a counterbalance weight  108 . Drive shaft  111  is equipped with a rotary actuator  115  which rotates within the drive shaft  111  where the rotary actuator  115  is preferably controlled by an external control source (not shown). The rotary actuator  115  includes a rotary actuator pin  114  which mates with a hole  125  on the cam bearing retainer  126  and can cause the cam bearing retainer  126  to pivot about the pivot pin  110  on the drive shaft  111 . That is, the cam bearing retainer  126  is seated on the drive shaft  111  at pivot pin  110  and the rotary actuator at pin  114 , and a rotation of the rotary actuator  115  will cause the pin  114  to rotate away from pivot pin  110 , which in turn causes the cam bearing retainer  126  to pivot or rotate about its seating at pivot pin  110 .  
         [0031]    Mounted on the cam bearing retainer  126  is the cam bearing  113 , which is analogous to the cam plate in the previous embodiment. Here, the cam bearing  113  rotates at input velocity rather than being stationary as in the case of the cam plate. The cam bearing  113  is mounted on the cam bearing support  129  and rotates therewith. In contact with the outer surface  130  of the cam bearing  113  are a plurality of shoes  120  each connected to a crankshaft  132 , where the shoes  120  are held in contact with the outer surface  130  by a torsional spring  102  or other conventional means which can maintain an adequate contact pressure.  
         [0032]    When the cam bearing  113  is at a zero eccentricity with respect to the centerline axis of input shaft  103  and output shaft  124 , the cam bearing  113  rotates with no orbital motion, and no angular force is applied to the shoes  120 . Because the shoes  120  are connected to the associated crankshafts  132  in a single direction relationship via one-way clutches  116 , in the zero eccentricity case there is no rotational force applied to the crankshaft  132 . As a consequence, the planet gears  121  are not actuated and there is no output velocity at output sun gear  122  or output shaft  124 .  
         [0033]    To initiate a rotational velocity in the output shaft  124 , the cam bearing retainer  126  is pivoted at pivot pin  110  by the rotary actuator  115  via the rotary actuator pin  114  such that the cam bearing  113  is eccentrically positioned with respect to the centerline axis of the input shaft  103 . This eccentricity causes the cam bearing  113 , which is no longer centered on the centerline, to orbit eccentrically about the centerline. This orbiting causes the shoes  120  in contact with the outer surface of the cam bearing to be rotated radially outward from the centerline. Shoe  120  is mounted on pin  133  which is fixed to crankshaft  132 , and the “lifting” of the shoe by the orbiting cam bearing  113  imparts a rotation of the crankshaft  132  as the shoe  120  moves with the orbiting of the cam bearing  113 . The torsional springs  102  maintain the shoes  120  in contact with the cam bearing&#39;s outer surface  130 , and as the cam bearing orbits it produces a corresponding rotation of the crankshaft shaft  118 . The crankshaft shaft  118  engages the overrunning one-way clutch  116  which controls the associated planet gear  121 . With the plurality of shoes  120  each actuating the associated planet gears  121  as just described, the sun gear  122  rotates with a constant rotational velocity governed by the fastest rotating planet gear due to the overrunning clutches  116 . Thus, motion is imparted to each planet gear in turn. The rotation of the sun gear  122  is directly imparted to the output shaft  124 .  
         [0034]    As the cam bearing retainer is moved from concentricity to eccentricity, an unbalance in the drive shaft  111  is generated. However, the counterbalance weight  108  which pivots on pivot pin  107  operates to balance the drive shaft  111  when in eccentric mode. As the rotary actuator  115  is energized to rotate, pin  109  moves the counterbalance weight  108  outward to balance the drive shaft  111 .  
         [0035]    In FIGS. 3 and 4, a third embodiment of the invention is disclosed. Input shaft  201  is supported by needle bearing  205  mounted in output shaft  223  and sleeve bearing  229  mounted in center section  219 . Although the input shaft  201  and the output shaft  223  are shown on the same side of the transmission, the output shaft can also be located on the opposite side of the transmission. The output shaft  223  is supported by sleeve bearing  232  and sleeve bearing  231 .  
         [0036]    The input drive shaft  201  is equipped with an actuator rod  225  supported by and sliding on sleeve bearing  210 , sleeve bearing  226 , and sleeve bearing  228 . These sleeve bearings are mounted within member  234  which comprises part of the input shaft  201 . Counterweights  224  are supported by support arms  235  which are positioned radially by a guide  236  which rides in slot  222 . Cam actuator  202  with cam bearing  203  are mounted onto input shaft  201  but are free to move in the radial direction. This assembly is guided by slot  238 . This assembly is analogous to the cam plate in FIG. 1, but the actuator assembly rotates at input velocity (unlike the cam plate in FIG. 1). Mounted within the cam actuator  202  is a roller bearing  227  which rotates on pin  233 . Of course, anti-friction bearings such as ball, roller or needle bearings may be used in place of the sleeve bearings when applicable.  
         [0037]    A plurality of cam followers  204  are in contact with the cam bearing  203  and each are connected to a crank  206  which forms a part of crankshaft  207 . In this embodiment the followers  204  are held in contact with the cam bearing  203  by a spring  240  contained in spring housing  241 . Spring housing  241  includes ears  239  used to mount the spring housings  241  and the springs  240  are clocked to apply the proper load on the cam followers  204  with respect to cam bearing  203 . Other means to maintain an adequate contact force to overcome inertia may be substituted for the springs shown.  
         [0038]    The crankshaft  207  which includes crank  206  is supported by sleeve bearings  212 ,  208 , and  209 . Mounted on crankshaft  207  is a one way clutch  213  with an outer race that is captured in clutch support cup  214 . Sleeve bearing  212  are mounted in the housing at drive input end  211  and sleeve bearing  209  is mounted in the housing at the control end  216 . Mounted within the clutch support cup  214  is sleeve bearing  237  which permits the one way clutch  213  and planet gear  215  to overrun when a particular crankshaft is not driving the output shaft  223 . Control end cover  217  encloses the counter weight assembly  224  and  235 .  
         [0039]    When the actuator rod  225  moves inward towards the center of the housing, ramp  220  imparts a radial motion to roller bearing  227  which, in turn, moves the cam actuator  202  radially upward. The movement of the cam actuator results in an eccentricity on the cam actuator  202  and cam bearing  203  with respect to the input shaft  201 . The amount of eccentricity imparted to cam actuator  202  is dependent upon the stroke imparted to actuator rod  225 . When the cam actuator is at zero eccentricity and cam actuator  202  is concentric with respect to the centerline axis of input shaft  201 , the cam bearing  203  imparts no force and consequently no motion to the cam followers  204  or crank  206 . Because the cam followers  204  are connected to the associated crankshafts  207  in a single directional relationship via the one way clutches  213 , at zero eccentricity there is no rotational force applied to the crankshaft  206 . As a result, none of the one way clutches  213  are engaged and the planer gears  215  are not actuated. With the planet gears still there is no output velocity at output sun gear  218  or output shaft  223 .  
         [0040]    To initiate a rotational velocity in the output shaft  223 , the cam actuator  202  is moved radially outward by the ramp  220  on actuator rod  225 . Here, the actuator rod  225  is moved inward such that the ramp  220  acts on the roller bearings  227  moving the pin  233 , which in turn moves the cam bearing  203  outward radially to an eccentric position. This eccentricity of the cam bearing  203  causes the cam bearing to orbit about the centerline of the input shaft axis. This orbiting causes the followers  204  in contact with the surface of the cam bearing  203  to be moved radially outward from the centerline. Since the followers  204  are mounted to a crank  206  which is fixed to a corresponding crankshaft  207 , the radial movement of the crank through the followers  204  imparts a rotation to the crankshaft  207  as the followers move with the orbiting cam bearing  203 . The springs  240  maintain the followers in contact with the cam bearing  203 . As cam bearing  203  rotates it actuates each crankshaft in turn. The crankshaft with the highest rotational velocity engages the one way clutch  213  which engages planet gear  215 , while the other crankshafts having less than the highest rotational velocity are overrun. With a plurality of followers  204 , each actuating its associated one way clutch  213  and planet gear  215  as described, the sun gear  218  rotates with a constant rotational velocity governed by the fastest rotating planet gear due to the one way clutches. Thus, motion is imparted to each planet gear serially. The rotation of the sun gear  218  is directly imparted to the output shaft  223 .  
         [0041]    As the cam bearing  203  is moved from a concentric position to an eccentric position an unbalance in the input shaft is created. However, counterweight  224  moves in unison with the cam eccentric  202  and cam bearing  203 , but in an opposite direction. In this manner, the unbalance caused by the load on the input shaft is counteracted by the counterbalance.  
         [0042]    The first embodiment of the continuously variable transmission increases the rotational velocity of the input shaft at the output shaft in a continuous spectrum of ratios. This type of transmission is suitable for constant speed alternator drives, test equipment drives, machine tool drives, power take-off drives, and so forth, where the input velocity can vary and the output velocity has to remain constant, or where the output velocity should remain above the input velocity. The second and third embodiments differs from the first in that the output velocity is between the input velocity and zero. Such a transmission is especially suitable for all types of vehicle transmissions, hoisting devices, processing equipment, and others.  
         [0043]    Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiments can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.