Abstract:
A Contoured Radius Continuously Variable Transmission (CRCVT) varies the torque and speed of an output component relative to the torque and speed of the input component by forming the contour of a belt-like component so that the belt-like component&#39;s radial distance from the input and/or output axis is gradually altered from being uniform throughout its length to being varied for different periods along its length.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims benefit of U.S. Provisional Application Ser. No. 61/856,806, filed Jul. 22, 2013, which application is incorporated herein by reference in its entirety. 
    
    
     SUMMARY 
     The present disclosure relates to a continuously variable transmission (CVT) wherein the conversion of mechanical work between high force/low distance and low force/high distance is accomplished by varying the radius of a ring-like component relative to the input and/or output axis. This variation in radius produces a change in both the force and distance of an output component relative to an input component. Although the length variance ratio is limited, the system can be configured to produce a final output with increased gear ratio, for example from zero rotation (infinite torque) to maximum rotation (reduced torque). Having solidly interlocked power transmitting components, there is no possible means for loss of engagement (slippage) between components, short of component breakage. 
     The Contoured Radius Continuously Variable Transmission (CRCVT) provides significant advantages over other forms of continuously variable transmissions currently available in the following ways: 
     1. It does not depend on a smooth-surface, friction-based contact of torque transmitting parts to obtain variability; therefore, higher torques can be applied to the system without introducing significant wear to parts that drive each other by means of smooth surface contact or to parts that support significant side loads due to the excessive contact pressures needed to prevent slippage between components that are transmitting high torques. 
     2. It eliminates the energy losses associated with friction-based systems that rely on increasing friction between driving components to prevent slippage between them, as is common to belt and pulley type designs. Many belt designs accommodate higher torques by increasing the contacting surface area between driving and driven parts, as opposed to increasing the pressure between smooth-surface parts. This added surface area contact produces added friction, lowering overall efficiency. 
     3. It does not depend on the movement of fluid to obtain variability, as is the case with continuously variable hydrostatic transmissions; therefore, similar torque loads can be handled with much greater energy efficiency than hydrostatic transmissions. As is known in the art, significant friction is produced as fluid is moved through the pump and motor of a hydrostatic transmission. This friction results in significant energy losses. Friction losses of this nature are not present in the CRCVT. 
     4. It does not depend on the conversion of mechanical energy into electrical energy and back; therefore, electrical motors and/or generators and their accompanying electrical energy converters are not part of the system. This eliminates the drawbacks of electrical continuously variable transmissions such as high heat production, over sizing electrical components, or operating in environments poorly suited to electricity. 
     5. It provides a continuously smooth velocity output, which is not present in most one-way-clutch type designs. 
     6. It increases efficiency and machine life by eliminating components that change direction or fluctuate in speed, as in most one-way-clutch type designs. 
     7. It provides torque variance (in addition to speed variance), which is not present in some one-way-clutch type designs. 
     The CRCVT provides an efficient and effective means for continuously varying mechanical speed and torque. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 through 4  illustrate the design and operation of an example embodiment. The example embodiment uses a flexible ring, the exact contour of which is formed by adjustable sheaves. Since the adjustable sheaves do not rotate along with the ring, the ring should also have some means of reducing friction between the ring side surfaces and the sheave surfaces—rollers, bearing balls, bushings, etc. As the sheaves pivot slightly, the contour of the ring is varied from a circular shape that is coaxial with the input and output shafts to an “egg shape” that is eccentric to the input/output axes. The shape of the sheaves should be such that the contact circumference stays the same no matter what the contour of the ring. Slight variances can be accommodated by spring loading the sheaves against the sides of the ring. The shape of the sheaves should also be such that there is always a period of uniform radius for the smallest contour radius and a period of uniform radius for the largest contour radius. These periods of uniform radius provide a steady speed period wherein transmission of torque can be transferred from one one-way clutch to another. The steady speed periods also produce a uniform output when a uniform input is applied. 
       Having one-way clutches on the input shaft, the input shaft drives the radial arms during the large radius period when the rotational speed is slowest. During the small radius period, the radial arms override the input shaft because they are rotating faster. In a complimentary fashion, the output shaft is also driven by one-way clutches. However, since these clutches are being driven, it is the fastest rotations during the small radius period that drive the output. The slower rotations during the larger radius periods simply “under-ride” or slip backward relative to the output shaft speed. In short, the asymmetry of the ring yields a faster output than input. As the ring is reshaped to a perfect circle with equal radial distance from the axis of rotation, the output speed gradually comes to equal the input speed. This is how the continuous variability of the CRCVT is produced. 
       If a zero maximum speed output is desired, the input can be reversed and summed with the output through differential gearing so that when input/output clutch speeds are equal, the combined output is zero; and, as the clutch output speed becomes greater than the clutch input speed, the combined output gradually increases. This then creates an infinitely variable version of the CRCVT. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an angled perspective view and  FIG. 2  shows a straight axial view of the example embodiment&#39;s drive system. Input shaft  1  drives one-way input clutches  2  which in turn drive radial arms  4 , which are fastened to one-way input clutches  2  through connecting links  3 . Radial arms  4  drive contoured radius ring  6  by being linked to contoured radius ring  6  through linear bearings  5 , which pivot within the ring on pivot rods  27 . Transmission of torque from input shaft  1  to contoured ring  6  takes place only within a slowest rotation period  16 , when the radial distance from input shaft  1  to contoured radius ring  6  is the greatest. Contoured ring  6  changes from being driven to being the driver during a fastest rotation period  15 . Through the fastest rotation period  15 , contoured ring  6  drives one-way output clutches  7  by transmitting output torque through the same linear bearings  5 , radial arms  4 , and connecting links  3 , as they pass through the fastest rotation period  15 . Each radial arm  4  is connected to its own distinct connecting link  3 , which is connected to a distinct set of one-way clutches  2  (input) and  7  (output). As such, each radial arm  4  alternates between being driven by input shaft  1  through slowest rotation period  16  and being the driver of clutched output shaft  8  through fastest rotation period  15 . 
     In applications where a zero output is unnecessary, the output of the CRCVT can end with clutched output shaft  8 . However, in applications where a final output of zero is desirable, the output of clutched output shaft  8  can be combined with the input of input shaft  1  to produce a minimum final output of zero. In this case, input shaft  1  would drive input gear  10 ; input gear  10  would drive reversing gears  11 , and reversing gears  11  would drive reversed input  12 . Reversing gears  11  rotate on an axis that has a fixed position and orientation. Since reversed input  12  turns in a direction opposite that of clutched output shaft  8 , the rotation of a combined output differential  13  would be zero when reversed input  12  and clutched output shaft  8  rotate at the same speed. As the speed of clutched output shaft  8  is gradually increased relative to input shaft  1  and reversed input  12 , the final output of combined output differential  13  gradually increases. In this manner the output of the CRCVT can be continuously varied from zero to its maximum speed. 
       FIG. 3  shows a straight axial view and  FIG. 4  shows an angled perspective view of the example embodiment&#39;s ring contouring system. In application, the system would likely have two contouring sheaves  17 , one on each side of contoured radius ring  6 , as opposed to just one as shown. Since the adjustable sheaves do not rotate along with the ring, the ring should also have some means of reducing friction between the ring side surfaces and the sheave surfaces—rollers, bearing balls, bushings, etc. Ring rollers  14  are depicted in  FIG. 2 . 
     Contouring sheave  17  is shaped such that as it pivots slightly on pivot shaft  18 , the contour of its contact with the side surfaces of contoured radius ring  6  varies. The contact between contouring sheave  17  and the sides of contoured radius ring  6  is depicted as contact lines  20 ,  20 A,  20 B, and  20 C. Contact planes  24  are depicted on the right side of  FIG. 3 . As the 3-dimensional contouring sheave  17  intersects with the 2-dimensional intersection planes  24 , an intersecting contact line  20 A,  20 B, and  20 C is derived. This intersecting contact line represents the contour of contoured radius ring  6  as contouring sheave  17  is pressed up against the sides of contoured radius ring  6 . 
     In its zero output position, the angle of contouring sheave  17  is such that contact line  20 A is perfectly circular, and its radial distance from the axis of input shaft  1  is uniform. In other words, contact line  20 A is a perfect circle with its center aligned to the center of input shaft  1 . Radius  25 A and radius  25 B are equal. When contouring sheave  17  is angled so that its resulting line of contact parallels  20 A the rotational speed of each radial arm  4  stays consistent for all 360 degrees of rotation. In this position the clutched input is equal to the clutched output. When contouring sheave  17  is angled so that its resulting line of contact parallels line  20 C the rotational speed of each radial arm  4  varies. When a radial arm  4  intersects with contoured radius ring  6  with a lengthened radius  26 B the rotational speed of that radial arm  4  at that point in its rotation will be slower than when that same radial arm  4  intersects with contoured radius ring  6  with a shortened radius  26 A. 
     Contact line  20 B represents the line of contact (between contouring sheave  17  and the sides of contoured radius ring  6 ) when contouring sheave is angled near the midway point between its zero discrepancy position contact line  20 A and its maximum discrepancy position contact line  20 C. At this midway point, contact line  20 B is not as far off center as contact line  20 C and its discrepancy between the longest and shortest radial lengths is not as pronounced as contact line  20 C. 
     The progression between contact line  20 A and contact line  20 C is gradual, as opposed to stepwise. Additionally, all contact lines throughout the gradual progression from  20 A to  20 B to  20 C have a period of uniform radius for the shortest radius  15  and a period of uniform radius for the longest radius  16 . 
     Pivot shaft  18  has rotational freedom within bushings  21 . Pivot arm  19  is representative of some means for pivoting contouring sheave  17  on pivot shaft  18 &#39;s axis. Springs  22  are representative of some means for pushing contouring sheaves  17  against the sides of contoured radius ring  6 , so as to take up any unwanted slack in contoured radius ring  6 . Anchor points  23  represent fixed points, perhaps on the housing of the transmission, to which springs  22  can be anchored. Springs  22  push bushings  21 . Bushings  21  push contouring sheave  17  by way of pivot shaft  18 , which is attached to contouring sheave  17 .