CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Patent Application No. 60/763,295 filed Jan. 30, 2006 the technical disclosures of which are hereby incorporated herein by reference.
TECHNICAL FIELD OF THE INVENTION The present invention relates to a continuously variable transmission and specifically to a means for shifting that transmission through a range of input/output ratios.
BACKGROUND OF THE INVENTION A transmission is any mechanical linkage that converts an input torque to an output torque. It usually involves a series of gears that have differing diameters, allowing a first gear at a first rotation rate to link to a second gear rotating at a second rate. The most common application for transmissions is in a vehicle. For example, a car may have an automatic transmission or a manual transmission. A bicycle has a simple transmission that links the pedals to the hub of the rear wheel.
Transmissions allow an input force to be converted into a more useful and appropriate output. However, by using gears and linkages, a typical transmission may only have four or five ratios available. For example, a four speed automatic transmission in a car has only four sets of output gears to couple to the engine's input. A ten speed bike has only ten ratios of input to output. A need exists for a transmission that is not limited by the number of gears. Yet, to place a larger number of gears into a transmission increases its costs and weight and space requirements.
A Continuously Variable Transmission (CVT) is a transmission that eliminates the need for a specified number of gears. Instead it allows an almost limitless number of input-to-output ratios. This allows an output (i.e. the speed of a vehicle) to be achieved at an optimal input (i.e. the rpm of the engine). For example, an engine might be most efficient at 1800 rpm. The peak torque output for the engine might be achieved at this engine rpm, or perhaps the highest fuel economy. Yet, in third gear, the car might be going faster at 1800 rpm than the driver desires. A continuously variable transmission would allow an intermediate ratio to be achieved that allowed the optimal input to achieve the desired output.
There are several examples of CVTs. U.S. Pat. No. 6,419,608 entitled “Continuously Variable Transmission” is owned by Fallbrook Technologies of Fallbrook, Calif. It discloses a CVT that uses a series of rolling spheres, also called power adjusters, to couple the input and output.
Referring to FIGS. 1 and 2, a prior art continuously variable transmission 100 is disclosed such as the one in the Fallbrook Technologies '608 patent. The transmission 100 is shrouded in a hub shell 40 covered by a hub cap 67. At the heart of the transmission 100 are three or more power adjusters 1a, 1b, 1c which are spherical in shape and are circumferentially spaced equally around the centerline or axis of rotation of the transmission 100.
As seen more clearly in Figure. 2, spindles 3a, 3b, 3c are inserted through the center of the power adjusters 1a, 1b, 1c to define an axis of rotation for the power adjusters 1a, 1b, 1c. In FIG. 1, the power adjuster's axis of rotation is shown in the horizontal direction. Spindle supports 2a-2f are attached perpendicular to and at the exposed ends of the spindles 3a, 3b, 3c. In one embodiment, each of the spindles supports has a bore to receive one end of one of the spindles 3a, 3b, 3c. The spindles 3a, 3b, 3c also have spindle rollers 4a-4f coaxially and slidingly positioned over the exposed ends of the spindles 3a, 3b, 3c outside of the spindle supports 2a-2f.
As the rotational axis of the power adjusters 1a, 1b, 1c is changed by tilting the spindles 3a, 3b, 3c, each spindle roller 4a-4f follows in a groove 6a-6f (see FIG. 3) cut into a stationary support 5a, 5b.
Referring to FIGS. 1 and 3, the stationary supports 5a, 5b are generally in the form of parallel disks with an axis of rotation along the centerline of the transmission 100. The grooves 6a-6f extend from the outer circumference of the stationary supports 5a, 5b towards the centerline of the transmission 100. While the sides of the grooves 6a-6f are substantially parallel, the bottom surface of the grooves 6a-6f forms a decreasing radius as it runs towards the centerline of the transmission 100. As the transmission 100 is shifted to a lower or higher gear by changing the rotational axes of the power adjusters 1a, 1b, 1c, each pair of spindle rollers 4a-4f moves in opposite directions along their respective grooves 6a-6f.
A centerline hole 7a, 7b in the stationary supports 5a, 5b allows the insertion of a hollow shaft 10 through both stationary supports 5a, 5b.
FIG. 4 is a plan view of a stationary support in accordance with the prior art. One or more of the stationary support holes 7a, 7b may have a non-cylindrical shape 14, which fits over a corresponding non-cylindrical shape 15 along the hollow shaft 10 to prevent any relative rotation between the stationary supports 5a, 5b and the hollow shaft 10. If the rigidity of the stationary supports 5a, 5b is insufficient, additional structure may be used to minimize any relative rotational movement or flexing of the stationary supports 5a, 5b. This type of movement by the stationary supports 5a, 5b may cause binding of the spindle rollers 4a-4f as they move along the grooves 6a-6f.
Referring back to FIGS. 1 and 3, the stationary support 5a is fixedly attached to a stationary support sleeve 42, which coaxially encloses the hollow shaft 10 and extends through the wall of the hub shell 40. The end of the stationary support sleeve 42 that extends through the hub shell 40 attaches to the frame support and preferentially has a non-cylindrical shape to enhance subsequent attachment of a torque lever 43. The torque lever 43 is placed over the non-cylindrical shaped end of the stationary support sleeve 42, and is held in place by a torque nut 44. The torque lever 43 at its other end is rigidly attached to a strong, non-moving part, such as a frame (not shown). A stationary support bearing 48 supports the hub shell 40 and permits the hub shell 40 to rotate relative to the stationary support sleeve 42.
Referring back to FIGS. 1 and 2, shifting is manually activated by axially sliding a rod 11 positioned in the hollow shaft 10. One or more pins 12 are inserted through one or more transverse holes in the rod 11 and further extend through one or more longitudinal slots 16 (not shown) in the hollow shaft 10. The slots 16 in the hollow shaft 10 allow for axial movement of the pin 12 and rod 11 assembly in the hollow shaft 10. As the rod 11 slides axially in the hollow shaft 10, the ends of the transverse pins 12 extend into and couple with a coaxial sleeve 19. The sleeve 19 is fixedly attached at each end to a substantially planar platform 13a, 13b forming a trough around the circumference of the sleeve 19.
As seen more clearly in FIG. 4, the planar platforms 13a, 13b each contact and push multiple wheels 21a-21f. The wheels 21a-21f fit into slots in the spindle supports 2a-2f and are held in place by wheel axles 22a-22f. The wheel axles 22a-22f are supported at their ends by the spindle supports 2a-2f and allow rotational movement of the wheels 21a-21f.
Referring back to FIGS. 1 and 2, the substantially planar platforms 13a, 13b transition into a convex surface at their outer perimeter (farthest from the hollow shaft 10). This region allows slack to be taken up when the spindle supports 2a-2f and power adjusters 1a, 1b, 1c are tilted as the transmission 100 is shifted. A cylindrical support member 18 is located in the trough formed between the planar platforms 13a, 13b and sleeve 19 and thus moves in concert with the planar platforms 13a, 13b and sleeve 19. The support member 18 rides on contact bearings 17a, 17b located at the intersection of the planar platforms 13a, 13b and sleeve 19 to allow the support member 18 to freely rotate about the axis of the transmission 100. Thus, the bearings 17a, 17b, support member 18, and sleeve 19 all slide axially with the planar platforms 13a, 13b when the transmission 100 is shifted.
Referring to FIGS. 3 and 4, stationary support rollers 30a-30l are attached in pairs to each spindle leg 2a-2f through a roller pin 31a-31f and held in place by roller clips 32a-32l. The roller pins 31a-31f allow the stationary support rollers 30a-30l to rotate freely about the roller pins 31a-31f. The stationary support rollers 30a-30l roll on a concave radius in the stationary support 5a, 5b along a substantially parallel path with the grooves 6a-f. As the spindle rollers 4a-4f move back and forth inside the grooves 6a-6f, the stationary support rollers 30a-30l do not allow the ends of the spindles 3a, 3 b, 3c nor the spindle rollers 4a-4f to contact the bottom surface of the grooves 6a-6f, to maintain the position of the spindles 3a, 3b, 3c, and to minimize any frictional losses.
While a continuously variable transmission is artful on paper, the realities of making one work smoothly requires significant know how. For example, a need exists for a method to axially shift the rod 11. Such a shifter would be useful in any environment that the CVT is used.
SUMMARY OF THE INVENTION The present invention relates to a shifter for use with a continuously variable transmission. Specifically, the shifter is designed for use on a bicycle, but could also be used with any light vehicle. The shifter has a grip portion and a hub portion. The grip portion is characterized by a rotatable adjuster that is coupled to a cable. The cable is also coupled to a hub portion. As the adjuster is rotated, the cable is pulled, in turn rotating a pulley assembly in the hub portion. As the pulley assembly is rotated, it advances a rod within a continuously variable transmission. The rod adjusts the power adjusters as described above.
The grip portion is also unique in its display of information to the rider. A cvt does not have a “gear”. Yet the average rider is conditioned to think in terms of riding in a particular gear, for example, fourth gear. Instead, with a cvt it is important for the user to think instead of the ratio between the input (the pedal rotation) and the output (the rear wheel rpm). So, the grip portion includes a display showing the ratio. The display also includes a filament that curves as the ration is adjusted. A high ratio renders the filament flat, and indeed this ratio is appropriate for riding on a relatively flat surface. The filament takes on a steep curve as the ratio is adjusted to make riding up hills easier.
BRIEF DESCRIPTION OF THE DRAWINGS The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
FIG. 1 is a cross section view of a continuously variable transmission in accordance with the prior art;
FIG. 2 is an exploded view showing the transmission “power adjusters” of the prior art;
FIGS. 3 is an exploded view of stationary supports in a continuously variable transmission in accordance with the prior art;
FIG. 4 is a plan view of a stationary support in accordance with the prior art;
FIG. 5 shows a handle grip portion of a shifter in accordance with the present invention;
FIG. 6a illustrates the hub portion of a shifter in accordance with the present invention;
FIG. 6b is a cross section view of the housing and pulley assembly of the present invention;
FIG. 6c provides an illustration of a typical bicycle that includes the shifter of the present invention;
FIG. 7 is a cutaway side plan view showing the pulley system in the housing;
FIG. 8a is a perspective view of the pulley system in accordance with the present invention;
FIG. 8b is an exploded view of the pulley system;
FIG. 8c is a reverse angle exploded view of the pulley system;
FIG. 9a is a perspective view of the hub housing mounted onto a wheel axle; h
FIG. 9b is a side plan view of the hub housing mounted onto a wheel axle;
FIG. 10a is a side top view of the pulley system interacting with the cables;
FIG. 10b is a side bottom view of the pulley system interacting with the cables;
FIG. 11a is an exploded view of the pulley system in relation to a bike wheel axle;
FIG. 11b is a reverse angle exploded view of the pulley system in relation to a bike wheel axle;
FIG. 12a is a side view of the pulley system mounted onto a bike wheel axle in accordance with the present invention;
FIG. 12b is a side plan view of the inner pulley mounted onto the wheel axle;
FIG. 12c is a side plan view of the outer pulley mounted onto the bike wheel axle;
FIG. 13 is a plan view of the inside surface of the outer pulley;
FIG. 14a is a perspective sectional view of the pulley system; and
FIG. 14b is a side cross section view of the pulley system.
DETAILED DESCRIPTION OF THE DRAWINGS FIG. 5 shows a bicycle handle grip portion of a shifter in accordance with the preferred embodiment of the present invention. The shifter has two portions, a rotatable hand grip 1000 located on the handle bars of the bicycle as pictured and a hub 1100 located near the axle of the rear wheel. The grip 1000 is also known as the ratio controller.
While riding the bicycle, the rider will grip cover portion 1002. As the rider encounters, for example, steeper terrain, he will want to alter the transmission ratio so that more rotations of the pedals (the input) produce fewer rotations of the rear wheel (the output). To alter this transmission ratio, the user rotates the adjuster 1004, which in turn manipulates cable 1012, 1014. The adjuster 1004 can include several indents to assist the rider.
A unique element of the shifter is a visual display 1010 of the input/output ratio. This is located on a housing 1008. A filament 1016 is attached to the display 1010. As the indicator 1018 moves from left to right, the filament 1016 changes shape from a flat line when all the way left to a curved line when all the way to the right. This visually represents the transmission ratio in relation to the terrain.
If the rider is on flat roads the indicator 1018 is all the way left (flat line), which sets the transmission to the highest ratio. When the rider is climbing a hill the indicator 1018 is all the way right, representing a hill (curved line) which sets the transmission to the lowest ratio. The indicator 1018 translates back and forth across the face and is controlled by a lead screw driven by the adjuster 1004. The scale is from 0 to 100%. Because this is a Constant Variable Transmission (CVT), there is not a specific “gear,” (e.g., fourth gear).
FIG. 6a illustrates the hub portion of a shifter in accordance with the present invention. The rear hub 1100 includes a pulley housing 1102 that encloses and protects a pulley system coupled to cables 1012 and 1014. The hub 1100 is also coupled to a CVT within hub body 1104. The CVT can be a type similar to the Fallbrook Technologies CVT described above, or could be any suitable design that allows for the adjustment of the power adjusters. The hub body 1104 should be relatively compact to fit concentrically with the axle of the rear wheel. Various mounting holes 1110 can be provided on the housing to facilitate mounting of spokes.
FIG. 6b is a cross section view of the housing and the pulley assembly in accordance with the present invention. The pulley system 1200 includes a pair of pulleys 1202 and 1204. First cable 1012 is attached to the first pulley 1202 so that a tension on the cable 1012 causes the pulley to rotate. Upon rotation, a rod 11 located axially with the pulleys translates in the axial direction. Similarly, second cable 1014 is attached to the second pulley 1204 so that a tension on the cable 1014 causes the pulley to rotate in the opposite direction than that of pulley 1202, thereby causing the rod to translate in the opposite axial direction.
FIG. 6c provides an illustration of a typical bicycle that includes the present shifter. The grip portion 1000 can be located on the handle bars. However the shifter could be also be located on around any tubular structure on the bicycle.
FIG. 7 is a cutaway side plan view showing the pulley system in the housing. This view shows the housing 1102 with the outside cover removed and illustrates the interaction between the cables 1012 and 1014 and the pulleys. Each cable is terminated into either pulley 1202 or 1204. As the adjuster 1004 on the handle is turned clockwise or counterclockwise, one cable is tensioned and rotated. Rotation of the pulleys produces a translation in rod 11 thereby shifting the CVT.
FIG. 8a is a perspective view of the pulley system in accordance with the present invention. This view shows the two pulleys 1202, 1204 mounted together. FIG. 8b is an exploded view of the pulley system. FIG. 8c is a reverse angle exploded view of the pulley system.
FIG. 9a is a perspective view of the hub housing mounted onto a wheel axle. FIG. 9b is a side plan view of the hub housing mounted onto the wheel axle. In the preferred embodiment, the front edge of the housing 1100 is trimmed to stay inside the chain guard of the bike.
FIG. 10a is a side top view of the pulley system interacting with the cables. FIG. 10b is a side bottom view of the pulley system. These views more clearly illustrates how cable 1012 attaches to pulley 1202 and cable 1014 attaches to pulley 1204. In the preferred embodiment, the cables 1012, 1014 are angled at four degrees. For the cable grooves in the pulleys 1202, 1204 opposing helixes were used to keep the cables 1012, 1014 in line.
FIG. 11a is an exploded view of the pulley system in relation to a bike wheel axle. FIG. 11b is a reverse angle exploded view of the pulley system. In the pre assembly state, the screws are left loose to fit the cables under the head of the M3 screws (shown in FIG. 14a-b). The holes in the wheel base are spaced at 20 degrees to allow for adjustable alignment to bicycle frame.
FIG. 12a is a side view of the pulley system mounted onto the bike wheel axle in accordance with the present invention. This view shows the two holes 1302, 1304 through which the cables 1012, 1014, respectively, are secured to the pulleys.
FIG. 12b is a side plan view of the inner pulley mounted onto the wheel axle. In this view, the outer pulley 1202 has been removed to provide a clearer view of pulley 1204. After the second cable 1014 is inserted through the hole 1304, it slide under the head of the fastener 1308 and up the ramp 1306.
FIG. 12c is a side plan view of the outer pulley mounted onto the bike wheel axle. The second cable 1014 continues from the ramp 1306 in the inner pulley 1204 through ramp 1310 in the outer pulley 1202 where it can be tensioned by hand by tightening screw 1312, cut, and put back into the ramp pocket Similarly, the first cable 1012 is inserted through hole 1302 in the outer pulley and slides under the fastener 1314, which is screwed down by hand. The cable is trimmed and place into the ramp pocket 1316 shown in the reverse plan view of the outer pulley in FIG. 13.
FIG. 14a is a perspective sectional view of the pulley system, and FIG. 14b is a side cross section view of the pulley system. The view in FIG. 14a shows the pulley system with the outer housing cover removed. Both of these views show a M3 screw 1402 which is used to secure the second cable 1014 in the inner pulley and the space 1404 through which the cable is threaded.
The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
