CA2801148C - Transmission - Google Patents
Transmission Download PDFInfo
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- CA2801148C CA2801148C CA2801148A CA2801148A CA2801148C CA 2801148 C CA2801148 C CA 2801148C CA 2801148 A CA2801148 A CA 2801148A CA 2801148 A CA2801148 A CA 2801148A CA 2801148 C CA2801148 C CA 2801148C
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- drive
- bevel gear
- helical
- wheel
- drive shaft
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- 230000005540 biological transmission Effects 0.000 title claims abstract description 52
- 230000033001 locomotion Effects 0.000 claims abstract description 45
- 230000036316 preload Effects 0.000 claims description 22
- 230000008878 coupling Effects 0.000 description 14
- 238000010168 coupling process Methods 0.000 description 14
- 238000005859 coupling reaction Methods 0.000 description 14
- 230000006835 compression Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 2
- 238000005381 potential energy Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 238000000418 atomic force spectrum Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H37/00—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00
- F16H37/12—Gearings comprising primarily toothed or friction gearing, links or levers, and cams, or members of at least two of these types
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
- B62M1/00—Rider propulsion of wheeled vehicles
- B62M1/24—Rider propulsion of wheeled vehicles with reciprocating levers, e.g. foot levers
- B62M1/26—Rider propulsion of wheeled vehicles with reciprocating levers, e.g. foot levers characterised by rotary cranks combined with reciprocating levers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
- B62M15/00—Transmissions characterised by use of crank shafts and coupling rods
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Transmission Devices (AREA)
- Gear Transmission (AREA)
Abstract
A transmission is disclosed comprising a crank, a drive shaft having a forward end and a rearward end, the drive shaft coupled to the crank at the forward end of the drive shaft, a drive spring coupled to drive shaft at the forward end of the drive shaft, the drive spring circumscribing the drive shaft, a helical drive adapted so as to allow the rearward end of drive shaft to pass through the helical drive, the helical drive further adapted to engage drive spring, the helical drive having a helical drive groove, and a drive bevel gear circumscribing helical drive, the drive bevel gear having a follower adapted to engage helical drive groove, drive bevel gear adapted to engage a wheel bevel gear, and a wheel coupled to wheel bevel gear, such that under rotation of the cranks, a force is imparted to the drive shaft and a force is imparted to the drive spring, such that drive shaft passes through helical drive, and helical drive is motivated rearwardly by drive spring, such that under the rearward movement of helical drive, helical drive groove imparts a rotational force on follower, which imparts a rotational force on helical drive gear, which imparts rotational force on wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate.
Description
TRANSMISSION
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BACKGROUND
Technical Field The present disclosure relates to transmissions including cycle transmissions including bicycle transmissions.
Description of the Related Art - The modern single speed bicycle has a crank actuated chain driven drivetrain. A chain runs from the crank to a sprocket which is coupled to the rear wheel.
When the crank is turned by the rider, the crank pulls the chain, the chain pulls the sprocket, and as the sprocket is coupled to the rear wheel, the turning of the sprocket rotates the rear wheel.
Modem bicycles have many different seating positions, including the upright position, the recumbent position, and a forward racing position. The position of the rider affects wind resistance, comfort and ease of pedaling. The chain drive bicycle transmission allows for the rider to sit in a generally upright position with their legs generally below them such that they can operate the cranks to turn the rear wheel, generally located behind the rider.
Chain drive bicycle transmissions allow for only one gear unless complex derailleurs and cogsets are employed. The derailleur system allows the rider to choose the gear ratio between the crank chain ring and the cogset. However, such a chain and derailleurs based transmission can only change the gear ratio when the chain and rear wheel are in motion.
US Patent No.: 6,199,884 employs a helical drive transmission actuated by a slider. The riders legs provide force to move the slider up and down. The slider has a notch which engages a helically twisted bar. The linear motion of the slider causes the helical bar to rotate. The helical bar has a bevel gear mounted at one end which engages a bevel gear coupled to the rear wheel and as such, via the twisting motion of the helical bar, the linear motion of the slider is converted into rotational motion.
The invention disclosed in US Patent No.: 6,199,884 suffers however, from significant drawbacks. Firstly, the rider is required to move their legs in a linear fashion, as opposed to the circular fashion used in the more common crank-based chain drive transmission. Secondly, the rider is required to position their feet radially from the rear wheel to actuate the skier.
BRIEF SUMMARY
A transmission is disclosed comprising a crank, a drive shaft, a drive spring, a helical drive having a helical drive groove, a yoke, a drive bevel gear having a follower, a wheel bevel gear and a wheel, whereby the crank is rotationally, coupled to the drive shaft and the drive spring is frictionally engaged between cranks and helical drive, and whereby the drive shaft is adapted to pass through helical drive, such that under rotation of the cranks, a force is imparted to the drive shaft, which passes through helical drive compressing drive spring and imparting a force on helical drive, and whereby helical drive is adapted to pass through yoke and drive bevel gear, and whereby drive bevel gear circumscribes helical drive such that the follower of drive bevel gear engages helical drive groove, such that the force imparted on helical drive by drive spring causes helical drive to pass through drive bevel gear and whereby the linear motion of helical drive groove relative to follower causes drive bevel gear to rotate, and whereby drive bevel gear is adapted to engage wheel bevel gear such that a rotation of drive bevel gear causes wheel bevel gear to rotate, and whereby wheel bevel gear is adapted to engage wheel such that rotation of wheel bevel gear causes wheel to rotate.
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BACKGROUND
Technical Field The present disclosure relates to transmissions including cycle transmissions including bicycle transmissions.
Description of the Related Art - The modern single speed bicycle has a crank actuated chain driven drivetrain. A chain runs from the crank to a sprocket which is coupled to the rear wheel.
When the crank is turned by the rider, the crank pulls the chain, the chain pulls the sprocket, and as the sprocket is coupled to the rear wheel, the turning of the sprocket rotates the rear wheel.
Modem bicycles have many different seating positions, including the upright position, the recumbent position, and a forward racing position. The position of the rider affects wind resistance, comfort and ease of pedaling. The chain drive bicycle transmission allows for the rider to sit in a generally upright position with their legs generally below them such that they can operate the cranks to turn the rear wheel, generally located behind the rider.
Chain drive bicycle transmissions allow for only one gear unless complex derailleurs and cogsets are employed. The derailleur system allows the rider to choose the gear ratio between the crank chain ring and the cogset. However, such a chain and derailleurs based transmission can only change the gear ratio when the chain and rear wheel are in motion.
US Patent No.: 6,199,884 employs a helical drive transmission actuated by a slider. The riders legs provide force to move the slider up and down. The slider has a notch which engages a helically twisted bar. The linear motion of the slider causes the helical bar to rotate. The helical bar has a bevel gear mounted at one end which engages a bevel gear coupled to the rear wheel and as such, via the twisting motion of the helical bar, the linear motion of the slider is converted into rotational motion.
The invention disclosed in US Patent No.: 6,199,884 suffers however, from significant drawbacks. Firstly, the rider is required to move their legs in a linear fashion, as opposed to the circular fashion used in the more common crank-based chain drive transmission. Secondly, the rider is required to position their feet radially from the rear wheel to actuate the skier.
BRIEF SUMMARY
A transmission is disclosed comprising a crank, a drive shaft, a drive spring, a helical drive having a helical drive groove, a yoke, a drive bevel gear having a follower, a wheel bevel gear and a wheel, whereby the crank is rotationally, coupled to the drive shaft and the drive spring is frictionally engaged between cranks and helical drive, and whereby the drive shaft is adapted to pass through helical drive, such that under rotation of the cranks, a force is imparted to the drive shaft, which passes through helical drive compressing drive spring and imparting a force on helical drive, and whereby helical drive is adapted to pass through yoke and drive bevel gear, and whereby drive bevel gear circumscribes helical drive such that the follower of drive bevel gear engages helical drive groove, such that the force imparted on helical drive by drive spring causes helical drive to pass through drive bevel gear and whereby the linear motion of helical drive groove relative to follower causes drive bevel gear to rotate, and whereby drive bevel gear is adapted to engage wheel bevel gear such that a rotation of drive bevel gear causes wheel bevel gear to rotate, and whereby wheel bevel gear is adapted to engage wheel such that rotation of wheel bevel gear causes wheel to rotate.
2 In another disclosed embodiment, a transmission is disclosed comprising a crank, a drive shaft, a helical drive having a helical drive groove, a yoke, a drive bevel gear having a follower, a wheel bevel gear and a wheel, whereby the crank is coupled the drive shaft, such that under rotation of the cranks, a force is imparted to the drive shaft and in turn, to the helical drive, and whereby helical drive is adapted to pass through yoke and drive bevel gear, and whereby drive bevel gear circumscribes helical drive such that the follower of drive bevel gear engages helical drive groove, such that the linear force imparted on helical drive by drive spring causes helical drive to pass through drive bevel gear and whereby the linear motion of helical drive groove relative to follower causes drive bevel gear to rotate, and whereby drive bevel gear is adapted to engage wheel bevel gear such that a rotation of drive bevel gear causes wheel bevel gear to rotate, and whereby wheel bevel gear is adapted to engage wheel such that rotation of wheel bevel gear causes wheel to rotate.
In another disclosed embodiment, the transmission may comprise a crank, a drive shaft having a forward end and a rearward end, the drive shaft coupled to the crank at the forward end of the drive shaft, a drive spring coupled to drive shaft at the forward end of the drive shaft, the drive spring circumscribing the drive shaft, a helical drive adapted so as to allow the rearward end of drive shaft to pass through the helical drive, the helical drive further adapted to engage drive spring, the helical drive having a helical drive groove, and a drive bevel gear circumscribing helical drive, the drive bevel gear having a follower adapted to engage helical drive groove, drive bevel gear adapted to engage a wheel bevel gear, and a wheel coupled to wheel bevel gear, such that under rotation of the cranks, a force is imparted to the drive shaft and a force is imparted to the drive spring, such that drive shaft passes through helical drive, and helical drive is motivated rearwardly by drive spring, such that under the rearward movement of helical drive, helical drive groove imparts a rotational force on follower, which imparts a rotational force on helical drive gear, which imparts rotational force on wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate.
In another disclosed embodiment, the transmission may comprise a crank, a drive shaft having a forward end and a rearward end, the drive shaft coupled to the crank at the forward end of the drive shaft, a drive spring coupled to drive shaft at the forward end of the drive shaft, the drive spring circumscribing the drive shaft, a helical drive adapted so as to allow the rearward end of drive shaft to pass through the helical drive, the helical drive further adapted to engage drive spring, the helical drive having a helical drive groove, and a drive bevel gear circumscribing helical drive, the drive bevel gear having a follower adapted to engage helical drive groove, drive bevel gear adapted to engage a wheel bevel gear, and a wheel coupled to wheel bevel gear, such that under rotation of the cranks, a force is imparted to the drive shaft and a force is imparted to the drive spring, such that drive shaft passes through helical drive, and helical drive is motivated rearwardly by drive spring, such that under the rearward movement of helical drive, helical drive groove imparts a rotational force on follower, which imparts a rotational force on helical drive gear, which imparts rotational force on wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate.
3 In another disclosed embodiment, the transmission may comprise a right side crank arm, a right side drive shaft having a forward end and a rearward end, the right side drive shaft coupled to the right side crank arm at the forward end of the right side drive shaft, a right side drive spring coupled to right side drive shaft at the forward end of the right side drive shaft, the right side drive spring circumscribing the right side drive shaft, a right side helical drive adapted so as to allow the rearward end of the right side drive shaft to pass through the right side helical drive, the right side helical drive further adapted to engage right side drive spring, the right side helical drive having a right side helical drive groove, and a right side drive bevel gear circumscribing right side helical drive, the right side drive bevel gear having a right side follower adapted to engage right side helical drive groove, right side drive bevel gear adapted to engage a right side wheel bevel gear, and a wheel coupled to right side wheel bevel gear, such that under rotation of the right side crank arm, a force is imparted to the right side drive shaft and a force is imparted to the right side drive spring, such that right side drive shaft passes through right side helical drive, and right side helical drive is motivated rearwardly by right side drive spring, such that under the rearward movement of right side helical drive, right side helical drive groove imparts a rotational force on right side follower, which imparts a rotational force on right side helical drive gear, which imparts rotational force on right side wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate, the transmission further comprising a left side crank arm, a left side drive shaft having a forward end and a rearward end, the left side drive shaft coupled to the left side crank arm at the forward end of the left side drive shaft, a left side drive spring coupled to left side drive shaft at the forward end of the left side drive shaft, the left side drive spring circumscribing the left side drive shaft, a left side helical drive adapted so as to allow the rearward end of the left side drive shaft to pass through the left side helical drive, the left side helical drive further adapted to engage left side drive spring, the left side helical drive having a left side helical drive groove, and a left side drive bevel gear circumscribing left side helical drive, the left side drive bevel gear
4 having a left side follower adapted to engage left side helical drive groove, left side drive bevel gear adapted to engage a left side wheel bevel gear, and a wheel coupled to left side wheel bevel gear, such that under rotation of the left side crank arm, a force is imparted to the left side drive shaft and a force is imparted to the left side drive spring, such that left side drive shaft passes through left side helical drive, and left side helical drive is motivated rearwardly by left side drive spring, such that under the rearward movement of left side helical drive, left side helical drive groove imparts a rotational force on left side follower, which imparts a rotational force on left side helical drive gear, which imparts rotational force on left side wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate.
Another embodiment includes a bicycle comprising a front wheel, a rear wheel, and a frame, the front wheel rotationally coupled to the frame, the rear wheel rotationally coupled to the frame, the bicycle further comprising a transmission, the transmission comprising a right side crank arm, a right side drive shaft having a forward end and a rearward end, the right side drive shaft coupled to the right side crank arm at the forward end of the right side drive shaft, a right side drive spring coupled to right side drive shaft at the forward end of the right side drive shaft, the right side drive spring circumscribing the right side drive shaft, a right side helical drive adapted so as to allow the rearward end of the right side drive shaft to pass through the right side helical drive, the right side helical drive further adapted to engage right side drive spring, the right side helical drive having a right side helical drive groove, and a right side drive bevel gear circumscribing right side helical drive, the right side drive bevel gear having a right side follower adapted to engage right side helical drive groove, right side drive bevel gear adapted to engage a right side wheel bevel gear, the rear wheel coupled to right side wheel bevel gear, such that under rotation of the right side crank arm, a force is imparted to the right side drive shaft and a force is imparted to the right side drive spring, such that right side drive shaft passes through right side helical drive, and right side helical drive is motivated rearwardly by right side drive spring, such that under the rearward movement of right side helical drive, right side helical drive groove imparts a rotational force on right side follower, which imparts a rotational force on right side helical drive gear, which imparts rotational force on right side wheel bevel gear, which imparts a rotational force on rear wheel such that when the rotational farce on rear wheel is sufficient to overcome opposing forces, rear wheel will rotate, the transmission further comprising a left side crank arm, a left side drive shaft having a forward end and a rearward end, the left side drive shaft coupled to the left side crank arm at the forward end of the left side drive shaft, a left side drive spring coupled to left side drive shaft at the forward end of the left side drive shaft, the left side drive spring circumscribing the left side drive shaft, a left side helical drive adapted so as to allow the rearward end of the left side drive shaft to pass through the left side helical drive, the left side helical drive further adapted to engage left side drive spring, the left side helical drive having a left side helical drive groove, and a left side drive bevel gear circumscribing left side helical drive, the left side drive bevel gear having a left side follower adapted to engage left side helical drive groove, left side drive bevel gear adapted to engage a left side wheel bevel gear, and the rear wheel coupled to left side wheel bevel gear, such that under rotation of the left side crank arm, a force is imparted to the left side drive shaft and a force is imparted to the left side drive spring, such that left side drive shaft passes through left side helical drive, and left side helical drive is motivated rearwardly by left side drive spring, such that under the rearward movement of left side helical drive, left side helical drive groove imparts a rotational force on left side follower, which imparts a rotational force on left side helical drive gear, which imparts rotational force on left side wheel bevel gear, which imparts a rotational force on the rear wheel such that when the rotational force on the rear wheel is sufficient to overcome opposing forces, rear wheel will rotate_ In another disclosed embodiment, the transmission many comprise a crank, a drive shaft having a forward end and a rearward end, the drive shaft coupled to the crank at the forward end of the drive shaft, a drive spring coupled to drive shaft at the forward end of the drive shaft, the drive spring circumscribing the drive shaft, a helical drive adapted so as to allow the rearward end of drive shaft to pass through the helical drive, the helical drive further adapted to engage drive spring, the helical drive having a helical drive groove, and a drive bevel gear circumscribing helical drive, the drive bevel gear having a follower adapted to engage helical drive groove, drive bevel gear adapted to engage a wheel bevel gear, and a wheel coupled to wheel bevel gear, such that under rotation of the cranks, a force is imparted to the drive shaft and a force is imparted to the drive spring, such that drive shaft passes through helical drive, and helical drive is motivated forwardly by drive spring, such that under the forward movement of helical drive, helical drive groove imparts a rotational force on follower, which imparts a rotational force on helical drive gear, which imparts rotational force on wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate.
The drive bevel gear may be adapted to ratchet so as to not impart a rearwardly rotational force to the wheel under forward motion of the helical drive.
In an embodiment, the wheel bevel gear may be adapted to ratchet so as to not impart a rearwardly rotational force to the wheel under forward motion of the helical drive.
In an embodiment, the crank may be comprised of a crank arm and a crank axel and wherein the drive shaft extends forwardly beyond the crank arm.
In an embodiment, the drive bevel may engage the wheel bevel gear at the rearward side of wheel bevel gear.
In an embodiment, the drive bevel may engage the wheel bevel gear at the forward side of wheel bevel gear.
In an embodiment, the transmission may further comprise a pre-load adjuster to adjust preload on drive spring.
BRIEF DESCRIPTION OF DRAWINGS
In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings.
Figure 1 is a perspective view of a transmission according to one embodiment.
Figure 'IA is a perspective exploded of a transmission according to one embodiment.
Figure 2 is a plan view of a transmission according to one embodiment.
Figure 3 is a top view of a transmission according to one embodiment.
Figure 4 is a perspective view of an embodiment of a drive bevel gear.
Figure 5 is a plan view of an embodiment of a drive bevel gear.
DESCRIPTION OF SPECIFIC EMBODIMENTS
In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known materials, structures and methods associated with transmissions have not been shown or described in detail, to avoid unnecessarily obscuring descriptions of the embodiments.
Unless the context requires otherwise, throughout the specification and claims which follow, the word "comprise" and variations thereof, such as, "comprises"
and "comprising" are to be construed in an open, inclusive sense, that is as "including, but not limited to."
Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the content clearly dictates otherwise.
It should also be noted that the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.
The headings and Abstract provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
The present disclosure discusses cycle transmissions. Figure 1 is a perspective view of a transmission 100 according to one embodiment. Figure 2 is a plan view of a transmission according to one embodiment. Figure 3 is a top view of a transmission according to one embodiment. In Figures 1, 2, and 3, cranks 10 have a left crank arm assembly 12 and a right crank arm assembly (not called out in Figure 1 for clarity), connected by a crank axel 13. Throughout Figures 1, 2, and 3, the elements for both side of the depicted two-sided transmission are not specifically called out for clarity. Crank axle 13 resides within the bicycle frame (not shown). Crank arm 12 is comprised of sub-crank-arms 12A and 12B. Sub crank arms 12A and 12B are coupled by a coupling shaft 14. Coupled to the outward sub-crank arm 12B, on each side, is a pedal 15. Coupled to coupling shaft 14 is a drive shaft 18. Drive shaft 18 is coupled to the coupling shaft 14 at the forward end of the drive shaft 18 in such a way as to allow it to rotate about coupling shaft 14. Drive shaft 18 is coupled, at its rearward end, to a helical drive 20. Drive shaft 18 has a primary axis running from the coupling shaft 14 at the forward end to the helical drive 20 at its rearward end. Drive shaft 18 has an associated drive spring 22. Drive spring 22 is not fixed to drive shaft 18 along the length of drive spring 22. Drive spring 22 is free to move coaxially with drive shaft 18 except that it is stopped at the forward end by pre-load adjuster 34 and at the rearward end by helical drive 20. When cranks 10 are not under motive force by a rider, drive spring 22 may be under some compression between pre-load adjuster 34 and helical drive 20. In another embodiment, pre-load adjuster 34 may be located at helical drive 20, or may be eliminated.
Helical drive 20 is, in one embodiment, a cylindrical tube with a helical drive groove 24. Circumscribing helical drive is drive bevel gear 26. Drive bevel gear 26 has a follower 50 (not shown in Figure 1) on the inside of the drive bevel gear 26 which is adapted to engage helical drive groove 24 of helical drive 20.
Helical drive is housed within a yoke 32 which is rotationally coupled to a wheel axle (not shown) to rotate in the plane of the rotation of wheel 20 under motion of the helical drive 20 imparted by drive spring 22 imparted by cranks 10. That is, cranks impart a locomotive-style reciprocating motion on helical drive 20 which is driven through yoke 32 and yoke 32 is coupled to a wheel axle (not shown in Figure 1) to allow for such movement.
Wheel axle (not shown) runs within the wheel hub 38 and affixes the rear wheel to the bicycle frame (not shown). Drive bevel gear 26 is adapted to engage a wheel bevel gear 28. Wheel bevel gear 28 is coupled to the wheel 30.
As the rider imparts a force to cranks 10, cranks 10 turn in a rotating fashion. As cranks 10 rotate, a reciprocating motion is imparted on drive shaft 18.
Drive shaft 18 is adapted to push through cylindrical tube 23 of helical dive 20. In the embodiment shown in the Figures, a pre-load adjuster 34 is configured about drive shaft 18. Pre-load adjuster 34 serves two functions. Firstly, pre-load adjuster serves as a stop affixed to drive shaft 18 so as to prevent drive spring 20 from sliding off drive shaft 18. Pre-load adjuster 34 also serves to adjust the pre-load on drive spring 22. Thus, as drive shaft 18 is driven rearwardly under the motion of the cranks 10, and as drive shaft 18 slides through helical drive 10, pre-load adjuster 34 (or a simple stop employed instead of pre-load adjuster), imparts a force on drive spring 22 which in turn imparts a force on helical drive 20.
This force imposed on helical drive 20 by drive spring 22, urges helical drive 20 through yoke 32. Helical drive 20 does not rotate or twist. Rather, as helical drive 20 pushes through the yoke 32, the follower 50 (as shown in Figure 4) on drive bevel gear 26 (follower not shown in Figure 1) runs within helical drive groove 24. As helical drive 20 is advanced through follower on drive bevel gear 26 helical drive groove 24 twists, relative to drive bevel gear 26, the linear motion of helical drive 20 causes drive bevel gear 26 to rotate.
Drive bevel gear 26 is adapted to engage wheel bevel gear 28, and under rotation of the drive bevel gear 26, drive bevel gear 261mparts a rotational force to the wheel bevel gear 28. Wheel bevel gear 28is coupled to the wheel 20, the rotational motion of wheel bevel gear 28 imparts a rotational force to the wheel 30.
In operation, a force will be required to rotate wheel 30. Cranks 10 will be rotated by rider, or by some other means. Due to the generally circular rotation of cranks 10, at any point, the force imparted will have two orthogonal force components, or an x and y component. As cranks 10 rotate from the maximum forward position towards the maximum rearward position, the x component of the force will be imparted on drive shaft 18, such that drive shaft 18 will be pushed towards and through helical drive 20, but drive spring 22 will be stopped by helical drive 20, and will compress under the force imparted by cranks 10 reducing the distance between cranks 10 and helical drive 20. The x component of the force of cranks 10 will contribute to the force imparted on drive shaft 18. The y component of force will cause the drive shaft to pivot upwardly and downwardly with the rotation of the cranks 10, which is permitted by the pivoting nature of yoke 32.
The potential energy stored by the compression of drive spring 22 will be equal to the spring constant (a property of the spring) multiplied by the compression distance. As cranks 10 rotate, drive spring will continue to be compressed until the force imparted on the helical drive 20 by drive spring 22 overcomes the force required to push helical drive 20 through yoke 32. The force required to push helical drive 20 through yoke 32 is related to the force required to rotate the wheel 30. The force is directed from helical drive 20 to drive bevel gear 26, to wheel bevel gear 28, to wheel 30.
Helical drive groove 24 is not linear in degree of twist. Rather, the forward end of helical drive groove 24 has a slacker helical angle than the helical angle at the rearward end of helical drive groove 24. That is, the helical angle of helical drive groove 24 increases from the forward end to the rearward end. The greater the helical angle, the greater the rotation of drive bevel gear 26 will be for any given distance the helical drive 20, travels through the yoke 32, and in kind, the drive bevel gear 26. The particular helical angle at any one point along helical drive groove 24 yields a gear ratio as between the distance travelled by helical drive 20 through yoke 32 and the rotation of the drive bevel gear 26 and in turn the wheel bevel gear 28 and wheel 30.
Drive spring 22 will continue to be compressed under rotation of cranks 10 until the potential energy stored by drive spring 22 yields a force equal to the force to turn wheel 30. Drive spring 22 will then continue to be pushed at the forward end of drive spring 22 under continued rotation of cranks 10 but will also exert force on helical drive 20, pushing helical drive 20 through yoke 32. As helical drive 20 is pushed through yoke 32, the follower in drive bevel gear 26 will be engaged by helical drive groove 24, such that the linear motion of helical drive 20, will impart a rotation of drive bevel gear 26, as follower engages helical drive groove 24. Drive bevel gear 26 in turn engages wheel bevel gear 28, turning wheel 30.
As cranks 10 continue to be turned by rider, drive spring 24 will continue to exert force on helical drive 20 urging it through yoke 32. As helical drive 20 is pushed through yoke 32, the particular gear ratio Will adjust as the degree of twist of helical drive groove 20 changes over its length. For each stroke, drive spring 22 will push helical drive 20 through yoke 32, and in turn rotate wheel 30, an amount corresponding to the force exerted by rider. Where a rider exerts greater force, helical drive 20 will be pushed further through yoke 32 and will rotate wheel 30 a greater degree, provided the degree of force is sufficient to turn wheel 30.
As such, drive spring 22 will self select the appropriate gear ratio by pushing helical drive 20 through yoke 32 until the force exerted no longer exceeds the force required to rotate wheel 30 at that particular gear ratio, as determined by the degree of twist in helical drive groove 24.
Helical drive groove 24 may initially have a low degree of twist, increasing the degree of twist from the forward end of helical drive 20 to the rearward end of helical drive 20. The twist profile of helical drive groove 24 along its length may increase at a rate that may be selected for a particular rider's pedal stroke force profile, or preference. The twist profile of helical drive groove 24 along its length may increase at variable rate, decrease, or may be flat for some portion of the profile.
Drive spring 24 may be selected with a particular spring constant for a particular rider's force ability or preference, which may be affected by the rider's strength and weight. Further, drive shaft 18 may include a means to adjust pre-load or adjust spring constant, dependant on the type of spring used in a particular embodiment, as is described elsewhere herein.
The force of each side of the cranks 10 will only impart a forward motion to wheel 30 for 180 degrees of a 360 degree rotation. For the remainder of the degree stroke, each side of cranks 10 will result in a 180 degree of return stroke.
When a particular side of cranks 10 transition from a drive stroke to a return stroke, the respective side of drive spring 22 and drive shaft 18 will transition from being pushed rearward to being pulled forward. As drive spring 24 and drive shaft 18 are pulled forward, drive spring 24 will be decompressed and drive shaft 18 will pull back through helical drive 20. Drive shaft 18 has a stop 36 at the end of drive shaft 12 such that it will engage the helical drive 20 on the return stroke as drive shaft 18 is pulled forward by cranks 10, as shown in Figure 1A. This force will pull drive shaft 18 back through yoke 32. As helical drive 20 is pulled forward, helical drive groove 24 engages follower in drive bevel gear 26. Without a ratchet or freewheel mechanism, this forward motion of helical drive 20 would tend to impart a backwards rotational force to wheel 30. Thus, one or both of drive bevel gear 26, or wheel bevel gear 28 are adapted to ratchet or freewheel so that the forward motion of helical drive 20 does not impart a forward =
rotating force on wheel 30. Freewheel assemblies for rear wheels of bicycles are well known in the art With each 360 degree rotation of cranks, first the right drive spring 22 is pushing its respective helical drive 20 through its respective yoke 32, such that drive bevel gear 26, via follower (not shown in Figure 1), engages helical drive groove 24 to impart a force on wheel bevel gear 28 to rotate wheel 30 forward. As one crank arm 12 is engaged in the drive stroke, the opposite crank will be engaged in the return stroke, described above, such that at least one side of crank 10 is imparting force to its respective drive spring 22 to result in forward motion of wheel 30 throughout both of the sequential 180 degree semi-rotations of cranks 10.
Cranks 10 are turned in a circular motion On the drive stroke, the circular motion of cranks 10 pulls the forward end of drive shaft 18 downwardly, relative to the axis running from the crank axle 13 to the axis of the wheel bevel gear 28. On the return stroke, the circular motion of cranks 10 pulls the forward end of drive shaft 18 upwardly, relative to the axis running from the crank axle 13 to the wheel bevel gear 28.
Yoke 32 is coupled concentrically with wheel bevel gear 28 such that it can rotate about the axis of wheel bevel gear 28 and swivel to accommodate the upwardly and downwardly motion imparted by cranks 10 on the forward end of drive shaft 18.
In the embodiment shown in the Figures, cranks 10 have crank arms 12.
Each crank arm has two sub-crank arms 12A and 12B coupled by coupling shaft 14.
Drive shaft 18 is coupled to the cranks at the coupling shaft 14_ A person of ordinary skill in the art could replace the cranks in the depicted embodiment with traditional =
cranks where crank arms do not have sub-crank arms and where drive shaft would be coupled to crank arm at the pedal axel.
In the embodiment shown in the Figures, coupling shaft extends forwardly from crank arm 12 to increase the length of drive shaft 18 beyond the distance between crank arm 12 and yoke 32. A longer drive shaft 18 allows for a longer drive spring 22 which may allow for a drive spring 22 of preferred spring characteristics. A
person of ordinary skill in the art could replace coupling shaft 14 such that it does not extend forwardly from crank arm 12. Dive shaft 18 may be located such that it extends forwardly below coupling shaft 14 but could be coupled to coupling shaft 14 at coupling shaft 14, or above coupling shaft 14. In the Figures, drive shaft 18 is shown such that it extends forwardly and above coupling shaft 14.
In the embodiment shown in the Figures, yoke 32 and drive bevel gear 26 are positioned such that drive bevel gear 26 engages wheel bevel gear 28 at the rearward side of drive bevel gear 28. A person of ordinary skill in the art could replace yoke 32 such that drive bevel gear 26 engages wheel bevel gear 28 at the forward side of wheel bevel gear 28. Where drive bevel gear 26 engages wheel bevel gear 28 at the forward side of wheel bevel gear 28, the helical drive groove 24 in helical drive 20 would have to be reversed so that drive bevel gear 26 imparted a forward rotational motion on wheel bevel gear 28. Further, the embodiments show a configuration where the helical drive 20 is urged through the drive bevel gear 26 such that the force is imparted on the wheel 30 as helical drive 20 is urged rearwardly. A person of ordinary skill in the art would appreciate that the helical drive groove 24 could be reversed, and the ratchet mechanism could be reversed such that a forward turning force is imparted on wheel 30 as helical drive 20 is pulled forwardly through drive bevel gear.
In the embodiment shown in the Figures, drive spring 22 is a helical spring circumscribing drive shaft 18. A person of ordinary skill in the art may replace drive spring 22 with an inline helical spring, or drive shaft may be telescoping with an associated slave spring. Springs may be helical, or gas, elastomeric, or other spring types known in the art. A drive shaft 18 may also provide direct force to helical drive 20 and not provide spring actuated force to helical drive 20.
In the embodiment shown in the Figures, a pre-load adjuster 34 is configured about drive shaft 18, to adjust the pre-load on drive spring 22, altering the force imparted by the drive spring 22 on helical drive 20 throughout the stroke of cranks 10. A person of ordinary skill in the art may elect to include a pre-load adjuster, of a form known in the art, or may elect to exclude preload adjuster 34.
In the embodiment shown in the Figures, a stop 36 (specifically shown in Figure 1A) is located at the rearward end of drive shaft 18 to prevent drive shaft 18 from forwardly pulling out of helical drive 20. The form of stop 36 may be selected by a person of ordinary skill in the art. Stop 36 may be configured to also act as a preload-adjuster for drive spring 22. For example, stop 36 may be a nut threaded onto drive shaft 18 such that the greater distance stop 36 is forwardly threaded on drive shaft 18, the greater the pre-load imparted on drive spring 22.
In the embodiment shown in the Figures, a tubular helical drive 20 is shown with a helical groove 24 therein. A helical drive 20 may have a single helical groove 24 therein, or may have a plurality of helical grooves. Drive bevel gear 26 may have the same number of followers 50 as helical drive grooves, one follower corresponding to each helical drive groove. Drive bevel gear 26 may have less than the number of helical drive grooves, if desired. A person of ordinary skill in the art may substitute a heical drive of the form disclosed in US Patent 6,199,884, in Figures 9,10,11 for example, in place of the tubular helical drive groove disclosed herein. In such cases, drive bevel gear could include a slot shaped follower, adapted to received the helically twisted bar drive.
Figure 4 is a perspective view of an embodiment of a drive bevel gear 26 showing followers 50 of a tooth embodiment.
Figure 6 is a plan view of another embodiment of a drive bevel gear 26 with followers 50 of a ball bearing embodiment, ball bearing follower 50 being disposed within the space defined by the helical groove 24 and drive bevel gear 26.
A person of ordinary skill in the art will, recognize that the disclosed embodiments could be implemented in a bicycle, tricycle, or other human powered wheeled conveyances. Further, the disclosed embodiments could be implemented in motorized machines as well.
The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Although specific embodiments of and examples are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the disclosure, as will be recognized by those skilled in the relevant art. The teachings provided herein of the various embodiments can be applied to other fiber reinforced materials, not necessarily the exemplary methods and apparatus generally described above. For example, the various embodiments described above can be combined to provide further embodiments.
These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.
Accordingly, the claims are not limited by the disclosure 1.7
Another embodiment includes a bicycle comprising a front wheel, a rear wheel, and a frame, the front wheel rotationally coupled to the frame, the rear wheel rotationally coupled to the frame, the bicycle further comprising a transmission, the transmission comprising a right side crank arm, a right side drive shaft having a forward end and a rearward end, the right side drive shaft coupled to the right side crank arm at the forward end of the right side drive shaft, a right side drive spring coupled to right side drive shaft at the forward end of the right side drive shaft, the right side drive spring circumscribing the right side drive shaft, a right side helical drive adapted so as to allow the rearward end of the right side drive shaft to pass through the right side helical drive, the right side helical drive further adapted to engage right side drive spring, the right side helical drive having a right side helical drive groove, and a right side drive bevel gear circumscribing right side helical drive, the right side drive bevel gear having a right side follower adapted to engage right side helical drive groove, right side drive bevel gear adapted to engage a right side wheel bevel gear, the rear wheel coupled to right side wheel bevel gear, such that under rotation of the right side crank arm, a force is imparted to the right side drive shaft and a force is imparted to the right side drive spring, such that right side drive shaft passes through right side helical drive, and right side helical drive is motivated rearwardly by right side drive spring, such that under the rearward movement of right side helical drive, right side helical drive groove imparts a rotational force on right side follower, which imparts a rotational force on right side helical drive gear, which imparts rotational force on right side wheel bevel gear, which imparts a rotational force on rear wheel such that when the rotational farce on rear wheel is sufficient to overcome opposing forces, rear wheel will rotate, the transmission further comprising a left side crank arm, a left side drive shaft having a forward end and a rearward end, the left side drive shaft coupled to the left side crank arm at the forward end of the left side drive shaft, a left side drive spring coupled to left side drive shaft at the forward end of the left side drive shaft, the left side drive spring circumscribing the left side drive shaft, a left side helical drive adapted so as to allow the rearward end of the left side drive shaft to pass through the left side helical drive, the left side helical drive further adapted to engage left side drive spring, the left side helical drive having a left side helical drive groove, and a left side drive bevel gear circumscribing left side helical drive, the left side drive bevel gear having a left side follower adapted to engage left side helical drive groove, left side drive bevel gear adapted to engage a left side wheel bevel gear, and the rear wheel coupled to left side wheel bevel gear, such that under rotation of the left side crank arm, a force is imparted to the left side drive shaft and a force is imparted to the left side drive spring, such that left side drive shaft passes through left side helical drive, and left side helical drive is motivated rearwardly by left side drive spring, such that under the rearward movement of left side helical drive, left side helical drive groove imparts a rotational force on left side follower, which imparts a rotational force on left side helical drive gear, which imparts rotational force on left side wheel bevel gear, which imparts a rotational force on the rear wheel such that when the rotational force on the rear wheel is sufficient to overcome opposing forces, rear wheel will rotate_ In another disclosed embodiment, the transmission many comprise a crank, a drive shaft having a forward end and a rearward end, the drive shaft coupled to the crank at the forward end of the drive shaft, a drive spring coupled to drive shaft at the forward end of the drive shaft, the drive spring circumscribing the drive shaft, a helical drive adapted so as to allow the rearward end of drive shaft to pass through the helical drive, the helical drive further adapted to engage drive spring, the helical drive having a helical drive groove, and a drive bevel gear circumscribing helical drive, the drive bevel gear having a follower adapted to engage helical drive groove, drive bevel gear adapted to engage a wheel bevel gear, and a wheel coupled to wheel bevel gear, such that under rotation of the cranks, a force is imparted to the drive shaft and a force is imparted to the drive spring, such that drive shaft passes through helical drive, and helical drive is motivated forwardly by drive spring, such that under the forward movement of helical drive, helical drive groove imparts a rotational force on follower, which imparts a rotational force on helical drive gear, which imparts rotational force on wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate.
The drive bevel gear may be adapted to ratchet so as to not impart a rearwardly rotational force to the wheel under forward motion of the helical drive.
In an embodiment, the wheel bevel gear may be adapted to ratchet so as to not impart a rearwardly rotational force to the wheel under forward motion of the helical drive.
In an embodiment, the crank may be comprised of a crank arm and a crank axel and wherein the drive shaft extends forwardly beyond the crank arm.
In an embodiment, the drive bevel may engage the wheel bevel gear at the rearward side of wheel bevel gear.
In an embodiment, the drive bevel may engage the wheel bevel gear at the forward side of wheel bevel gear.
In an embodiment, the transmission may further comprise a pre-load adjuster to adjust preload on drive spring.
BRIEF DESCRIPTION OF DRAWINGS
In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings.
Figure 1 is a perspective view of a transmission according to one embodiment.
Figure 'IA is a perspective exploded of a transmission according to one embodiment.
Figure 2 is a plan view of a transmission according to one embodiment.
Figure 3 is a top view of a transmission according to one embodiment.
Figure 4 is a perspective view of an embodiment of a drive bevel gear.
Figure 5 is a plan view of an embodiment of a drive bevel gear.
DESCRIPTION OF SPECIFIC EMBODIMENTS
In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known materials, structures and methods associated with transmissions have not been shown or described in detail, to avoid unnecessarily obscuring descriptions of the embodiments.
Unless the context requires otherwise, throughout the specification and claims which follow, the word "comprise" and variations thereof, such as, "comprises"
and "comprising" are to be construed in an open, inclusive sense, that is as "including, but not limited to."
Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the content clearly dictates otherwise.
It should also be noted that the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.
The headings and Abstract provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
The present disclosure discusses cycle transmissions. Figure 1 is a perspective view of a transmission 100 according to one embodiment. Figure 2 is a plan view of a transmission according to one embodiment. Figure 3 is a top view of a transmission according to one embodiment. In Figures 1, 2, and 3, cranks 10 have a left crank arm assembly 12 and a right crank arm assembly (not called out in Figure 1 for clarity), connected by a crank axel 13. Throughout Figures 1, 2, and 3, the elements for both side of the depicted two-sided transmission are not specifically called out for clarity. Crank axle 13 resides within the bicycle frame (not shown). Crank arm 12 is comprised of sub-crank-arms 12A and 12B. Sub crank arms 12A and 12B are coupled by a coupling shaft 14. Coupled to the outward sub-crank arm 12B, on each side, is a pedal 15. Coupled to coupling shaft 14 is a drive shaft 18. Drive shaft 18 is coupled to the coupling shaft 14 at the forward end of the drive shaft 18 in such a way as to allow it to rotate about coupling shaft 14. Drive shaft 18 is coupled, at its rearward end, to a helical drive 20. Drive shaft 18 has a primary axis running from the coupling shaft 14 at the forward end to the helical drive 20 at its rearward end. Drive shaft 18 has an associated drive spring 22. Drive spring 22 is not fixed to drive shaft 18 along the length of drive spring 22. Drive spring 22 is free to move coaxially with drive shaft 18 except that it is stopped at the forward end by pre-load adjuster 34 and at the rearward end by helical drive 20. When cranks 10 are not under motive force by a rider, drive spring 22 may be under some compression between pre-load adjuster 34 and helical drive 20. In another embodiment, pre-load adjuster 34 may be located at helical drive 20, or may be eliminated.
Helical drive 20 is, in one embodiment, a cylindrical tube with a helical drive groove 24. Circumscribing helical drive is drive bevel gear 26. Drive bevel gear 26 has a follower 50 (not shown in Figure 1) on the inside of the drive bevel gear 26 which is adapted to engage helical drive groove 24 of helical drive 20.
Helical drive is housed within a yoke 32 which is rotationally coupled to a wheel axle (not shown) to rotate in the plane of the rotation of wheel 20 under motion of the helical drive 20 imparted by drive spring 22 imparted by cranks 10. That is, cranks impart a locomotive-style reciprocating motion on helical drive 20 which is driven through yoke 32 and yoke 32 is coupled to a wheel axle (not shown in Figure 1) to allow for such movement.
Wheel axle (not shown) runs within the wheel hub 38 and affixes the rear wheel to the bicycle frame (not shown). Drive bevel gear 26 is adapted to engage a wheel bevel gear 28. Wheel bevel gear 28 is coupled to the wheel 30.
As the rider imparts a force to cranks 10, cranks 10 turn in a rotating fashion. As cranks 10 rotate, a reciprocating motion is imparted on drive shaft 18.
Drive shaft 18 is adapted to push through cylindrical tube 23 of helical dive 20. In the embodiment shown in the Figures, a pre-load adjuster 34 is configured about drive shaft 18. Pre-load adjuster 34 serves two functions. Firstly, pre-load adjuster serves as a stop affixed to drive shaft 18 so as to prevent drive spring 20 from sliding off drive shaft 18. Pre-load adjuster 34 also serves to adjust the pre-load on drive spring 22. Thus, as drive shaft 18 is driven rearwardly under the motion of the cranks 10, and as drive shaft 18 slides through helical drive 10, pre-load adjuster 34 (or a simple stop employed instead of pre-load adjuster), imparts a force on drive spring 22 which in turn imparts a force on helical drive 20.
This force imposed on helical drive 20 by drive spring 22, urges helical drive 20 through yoke 32. Helical drive 20 does not rotate or twist. Rather, as helical drive 20 pushes through the yoke 32, the follower 50 (as shown in Figure 4) on drive bevel gear 26 (follower not shown in Figure 1) runs within helical drive groove 24. As helical drive 20 is advanced through follower on drive bevel gear 26 helical drive groove 24 twists, relative to drive bevel gear 26, the linear motion of helical drive 20 causes drive bevel gear 26 to rotate.
Drive bevel gear 26 is adapted to engage wheel bevel gear 28, and under rotation of the drive bevel gear 26, drive bevel gear 261mparts a rotational force to the wheel bevel gear 28. Wheel bevel gear 28is coupled to the wheel 20, the rotational motion of wheel bevel gear 28 imparts a rotational force to the wheel 30.
In operation, a force will be required to rotate wheel 30. Cranks 10 will be rotated by rider, or by some other means. Due to the generally circular rotation of cranks 10, at any point, the force imparted will have two orthogonal force components, or an x and y component. As cranks 10 rotate from the maximum forward position towards the maximum rearward position, the x component of the force will be imparted on drive shaft 18, such that drive shaft 18 will be pushed towards and through helical drive 20, but drive spring 22 will be stopped by helical drive 20, and will compress under the force imparted by cranks 10 reducing the distance between cranks 10 and helical drive 20. The x component of the force of cranks 10 will contribute to the force imparted on drive shaft 18. The y component of force will cause the drive shaft to pivot upwardly and downwardly with the rotation of the cranks 10, which is permitted by the pivoting nature of yoke 32.
The potential energy stored by the compression of drive spring 22 will be equal to the spring constant (a property of the spring) multiplied by the compression distance. As cranks 10 rotate, drive spring will continue to be compressed until the force imparted on the helical drive 20 by drive spring 22 overcomes the force required to push helical drive 20 through yoke 32. The force required to push helical drive 20 through yoke 32 is related to the force required to rotate the wheel 30. The force is directed from helical drive 20 to drive bevel gear 26, to wheel bevel gear 28, to wheel 30.
Helical drive groove 24 is not linear in degree of twist. Rather, the forward end of helical drive groove 24 has a slacker helical angle than the helical angle at the rearward end of helical drive groove 24. That is, the helical angle of helical drive groove 24 increases from the forward end to the rearward end. The greater the helical angle, the greater the rotation of drive bevel gear 26 will be for any given distance the helical drive 20, travels through the yoke 32, and in kind, the drive bevel gear 26. The particular helical angle at any one point along helical drive groove 24 yields a gear ratio as between the distance travelled by helical drive 20 through yoke 32 and the rotation of the drive bevel gear 26 and in turn the wheel bevel gear 28 and wheel 30.
Drive spring 22 will continue to be compressed under rotation of cranks 10 until the potential energy stored by drive spring 22 yields a force equal to the force to turn wheel 30. Drive spring 22 will then continue to be pushed at the forward end of drive spring 22 under continued rotation of cranks 10 but will also exert force on helical drive 20, pushing helical drive 20 through yoke 32. As helical drive 20 is pushed through yoke 32, the follower in drive bevel gear 26 will be engaged by helical drive groove 24, such that the linear motion of helical drive 20, will impart a rotation of drive bevel gear 26, as follower engages helical drive groove 24. Drive bevel gear 26 in turn engages wheel bevel gear 28, turning wheel 30.
As cranks 10 continue to be turned by rider, drive spring 24 will continue to exert force on helical drive 20 urging it through yoke 32. As helical drive 20 is pushed through yoke 32, the particular gear ratio Will adjust as the degree of twist of helical drive groove 20 changes over its length. For each stroke, drive spring 22 will push helical drive 20 through yoke 32, and in turn rotate wheel 30, an amount corresponding to the force exerted by rider. Where a rider exerts greater force, helical drive 20 will be pushed further through yoke 32 and will rotate wheel 30 a greater degree, provided the degree of force is sufficient to turn wheel 30.
As such, drive spring 22 will self select the appropriate gear ratio by pushing helical drive 20 through yoke 32 until the force exerted no longer exceeds the force required to rotate wheel 30 at that particular gear ratio, as determined by the degree of twist in helical drive groove 24.
Helical drive groove 24 may initially have a low degree of twist, increasing the degree of twist from the forward end of helical drive 20 to the rearward end of helical drive 20. The twist profile of helical drive groove 24 along its length may increase at a rate that may be selected for a particular rider's pedal stroke force profile, or preference. The twist profile of helical drive groove 24 along its length may increase at variable rate, decrease, or may be flat for some portion of the profile.
Drive spring 24 may be selected with a particular spring constant for a particular rider's force ability or preference, which may be affected by the rider's strength and weight. Further, drive shaft 18 may include a means to adjust pre-load or adjust spring constant, dependant on the type of spring used in a particular embodiment, as is described elsewhere herein.
The force of each side of the cranks 10 will only impart a forward motion to wheel 30 for 180 degrees of a 360 degree rotation. For the remainder of the degree stroke, each side of cranks 10 will result in a 180 degree of return stroke.
When a particular side of cranks 10 transition from a drive stroke to a return stroke, the respective side of drive spring 22 and drive shaft 18 will transition from being pushed rearward to being pulled forward. As drive spring 24 and drive shaft 18 are pulled forward, drive spring 24 will be decompressed and drive shaft 18 will pull back through helical drive 20. Drive shaft 18 has a stop 36 at the end of drive shaft 12 such that it will engage the helical drive 20 on the return stroke as drive shaft 18 is pulled forward by cranks 10, as shown in Figure 1A. This force will pull drive shaft 18 back through yoke 32. As helical drive 20 is pulled forward, helical drive groove 24 engages follower in drive bevel gear 26. Without a ratchet or freewheel mechanism, this forward motion of helical drive 20 would tend to impart a backwards rotational force to wheel 30. Thus, one or both of drive bevel gear 26, or wheel bevel gear 28 are adapted to ratchet or freewheel so that the forward motion of helical drive 20 does not impart a forward =
rotating force on wheel 30. Freewheel assemblies for rear wheels of bicycles are well known in the art With each 360 degree rotation of cranks, first the right drive spring 22 is pushing its respective helical drive 20 through its respective yoke 32, such that drive bevel gear 26, via follower (not shown in Figure 1), engages helical drive groove 24 to impart a force on wheel bevel gear 28 to rotate wheel 30 forward. As one crank arm 12 is engaged in the drive stroke, the opposite crank will be engaged in the return stroke, described above, such that at least one side of crank 10 is imparting force to its respective drive spring 22 to result in forward motion of wheel 30 throughout both of the sequential 180 degree semi-rotations of cranks 10.
Cranks 10 are turned in a circular motion On the drive stroke, the circular motion of cranks 10 pulls the forward end of drive shaft 18 downwardly, relative to the axis running from the crank axle 13 to the axis of the wheel bevel gear 28. On the return stroke, the circular motion of cranks 10 pulls the forward end of drive shaft 18 upwardly, relative to the axis running from the crank axle 13 to the wheel bevel gear 28.
Yoke 32 is coupled concentrically with wheel bevel gear 28 such that it can rotate about the axis of wheel bevel gear 28 and swivel to accommodate the upwardly and downwardly motion imparted by cranks 10 on the forward end of drive shaft 18.
In the embodiment shown in the Figures, cranks 10 have crank arms 12.
Each crank arm has two sub-crank arms 12A and 12B coupled by coupling shaft 14.
Drive shaft 18 is coupled to the cranks at the coupling shaft 14_ A person of ordinary skill in the art could replace the cranks in the depicted embodiment with traditional =
cranks where crank arms do not have sub-crank arms and where drive shaft would be coupled to crank arm at the pedal axel.
In the embodiment shown in the Figures, coupling shaft extends forwardly from crank arm 12 to increase the length of drive shaft 18 beyond the distance between crank arm 12 and yoke 32. A longer drive shaft 18 allows for a longer drive spring 22 which may allow for a drive spring 22 of preferred spring characteristics. A
person of ordinary skill in the art could replace coupling shaft 14 such that it does not extend forwardly from crank arm 12. Dive shaft 18 may be located such that it extends forwardly below coupling shaft 14 but could be coupled to coupling shaft 14 at coupling shaft 14, or above coupling shaft 14. In the Figures, drive shaft 18 is shown such that it extends forwardly and above coupling shaft 14.
In the embodiment shown in the Figures, yoke 32 and drive bevel gear 26 are positioned such that drive bevel gear 26 engages wheel bevel gear 28 at the rearward side of drive bevel gear 28. A person of ordinary skill in the art could replace yoke 32 such that drive bevel gear 26 engages wheel bevel gear 28 at the forward side of wheel bevel gear 28. Where drive bevel gear 26 engages wheel bevel gear 28 at the forward side of wheel bevel gear 28, the helical drive groove 24 in helical drive 20 would have to be reversed so that drive bevel gear 26 imparted a forward rotational motion on wheel bevel gear 28. Further, the embodiments show a configuration where the helical drive 20 is urged through the drive bevel gear 26 such that the force is imparted on the wheel 30 as helical drive 20 is urged rearwardly. A person of ordinary skill in the art would appreciate that the helical drive groove 24 could be reversed, and the ratchet mechanism could be reversed such that a forward turning force is imparted on wheel 30 as helical drive 20 is pulled forwardly through drive bevel gear.
In the embodiment shown in the Figures, drive spring 22 is a helical spring circumscribing drive shaft 18. A person of ordinary skill in the art may replace drive spring 22 with an inline helical spring, or drive shaft may be telescoping with an associated slave spring. Springs may be helical, or gas, elastomeric, or other spring types known in the art. A drive shaft 18 may also provide direct force to helical drive 20 and not provide spring actuated force to helical drive 20.
In the embodiment shown in the Figures, a pre-load adjuster 34 is configured about drive shaft 18, to adjust the pre-load on drive spring 22, altering the force imparted by the drive spring 22 on helical drive 20 throughout the stroke of cranks 10. A person of ordinary skill in the art may elect to include a pre-load adjuster, of a form known in the art, or may elect to exclude preload adjuster 34.
In the embodiment shown in the Figures, a stop 36 (specifically shown in Figure 1A) is located at the rearward end of drive shaft 18 to prevent drive shaft 18 from forwardly pulling out of helical drive 20. The form of stop 36 may be selected by a person of ordinary skill in the art. Stop 36 may be configured to also act as a preload-adjuster for drive spring 22. For example, stop 36 may be a nut threaded onto drive shaft 18 such that the greater distance stop 36 is forwardly threaded on drive shaft 18, the greater the pre-load imparted on drive spring 22.
In the embodiment shown in the Figures, a tubular helical drive 20 is shown with a helical groove 24 therein. A helical drive 20 may have a single helical groove 24 therein, or may have a plurality of helical grooves. Drive bevel gear 26 may have the same number of followers 50 as helical drive grooves, one follower corresponding to each helical drive groove. Drive bevel gear 26 may have less than the number of helical drive grooves, if desired. A person of ordinary skill in the art may substitute a heical drive of the form disclosed in US Patent 6,199,884, in Figures 9,10,11 for example, in place of the tubular helical drive groove disclosed herein. In such cases, drive bevel gear could include a slot shaped follower, adapted to received the helically twisted bar drive.
Figure 4 is a perspective view of an embodiment of a drive bevel gear 26 showing followers 50 of a tooth embodiment.
Figure 6 is a plan view of another embodiment of a drive bevel gear 26 with followers 50 of a ball bearing embodiment, ball bearing follower 50 being disposed within the space defined by the helical groove 24 and drive bevel gear 26.
A person of ordinary skill in the art will, recognize that the disclosed embodiments could be implemented in a bicycle, tricycle, or other human powered wheeled conveyances. Further, the disclosed embodiments could be implemented in motorized machines as well.
The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Although specific embodiments of and examples are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the disclosure, as will be recognized by those skilled in the relevant art. The teachings provided herein of the various embodiments can be applied to other fiber reinforced materials, not necessarily the exemplary methods and apparatus generally described above. For example, the various embodiments described above can be combined to provide further embodiments.
These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.
Accordingly, the claims are not limited by the disclosure 1.7
Claims (18)
1. A transmission comprising a crank, a drive shaft, a drive spring, a helical drive having a helical drive groove, a yoke, a drive bevel gear having a follower, a wheel bevel gear and a wheel, whereby the crank is rotationally coupled to the drive shaft and the drive spring is frictionally engaged between the crank and helical drive, and whereby the drive shaft is adapted to pass through helical drive, such that under rotation of the crank, a force is imparted to the drive shaft, which passes through helical drive compressing drive spring and imparting a force on helical drive, and whereby helical drive is adapted to pass through yoke and drive bevel gear, and whereby drive bevel gear circumscribes helical drive such that the follower of drive bevel gear engages helical drive groove, such that the force imparted on helical drive by drive spring causes helical drive to pass through drive bevel gear and whereby the linear motion of helical drive groove relative to follower causes drive bevel gear to rotate, and whereby drive bevel gear is adapted to engage wheel bevel gear such that a rotation of drive bevel gear causes wheel bevel gear to rotate, and whereby wheel bevel gear is adapted to engage wheel such that rotation of wheel bevel gear causes wheel to rotate.
2. The transmission of claim 1 wherein the drive bevel gear is adapted to ratchet so as to not impart a rearwardly rotational force to the wheel under forward motion of the helical drive.
3. The transmission of claim 1 wherein the wheel bevel gear is adapted to ratchet so as to not impart a rearwardly rotational force to the wheel under forward motion of the helical drive.
4. The transmission of claim 1 wherein the crank is comprised of a crank arm and a crank axel and wherein the drive shaft extends forwardly beyond the crank arm.
5. The transmission of claim 1 wherein the drive bevel engages the wheel bevel gear at the rearward side of wheel bevel gear.
6. The transmission of claim 1 wherein the drive bevel engages the wheel bevel gear at the forward side of wheel bevel gear.
7. The transmission of claim 1 further comprising a pre-load adjuster to adjust preload on drive spring.
8. A transmission comprising a crank, a drive shaft, a helical drive having a helical drive groove, a yoke, a drive bevel gear having a follower, a wheel bevel gear and a wheel, whereby the crank is coupled the drive shaft, such that under rotation of the crank, a force is imparted to the drive shaft and in turn, to the helical drive, and whereby helical drive is adapted to pass through yoke and drive bevel gear, and whereby drive bevel gear circumscribes helical drive such that the folloWer of drive bevel gear engages helical drive groove, such that the linear force imparted on helical drive by drive spring causes helical drive to pass through drive bevel gear and whereby the linear motion of helical drive groove relative to follower causes drive bevel gear to rotate, and whereby drive bevel gear is adapted to engage wheel bevel gear such that a rotation of drive bevel gear causes wheel bevel gear to rotate, and whereby wheel bevel gear is adapted to engage wheel such that rotation of wheel bevel gear causes wheel to rotate.
9. A transmission comprising a crank, a drive shaft having a forward end and a rearward end, the drive shaft coupled to the 'crank at the forward end of the drive shaft, a drive spring coupled to drive shaft at the forward end of the drive shaft, the drive spring circumscribing the drive shaft, a helical drive adapted so as to allow the rearward end of drive shaft to pass through the helical drive, the helical drive further adapted to engage drive spring, the helical drive having a helical drive groove, and a drive bevel gear circumscribing helical drive, the drive bevel gear having a follower adapted to engage helical drive groove, drive bevel gear adapted to engage a wheel bevel gear, and a wheel coupled to wheel bevel gear, such that under rotation of the crank, a farce is imparted to the drive shaft and a force is imparted to the drive spring, such that drive shaft passes through helical drive, and helical drive is motivated rearwardly by drive spring, such that under the rearward movement of helical drive, helical drive groove imparts a rotational force on follower, which imparts a rotational force on helical drive gear, which imparts rotational force on wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate.
10. The transmission of claim 9 wherein the drive bevel gear is adapted to ratchet so as to not impart a rearwardly rotational force to the wheel under forward motion of the helical drive.
11. The transmission of claim 9 wherein the wheel bevel gear is adapted to ratchet so as to not impart a rearwardly rotational force to the wheel under forward motion of the helical drive.
12. The transmission of claim 9 wherein the crank is comprised of a crank arm and a crank axel and wherein the drive shaft extends forwardly beyond the crank arm.
13. The transmission of claim 9 wherein the drive bevel engages the wheel bevel gear at the rearward side of wheel bevel gear.
14. The transmission of claim 9 wherein the drive bevel engages the wheel bevel gear at the forward side of wheel bevel gear.
15. The transmission of claim 9 further comprising a preload adjuster to adjust preload on drive spring.
16. A transmission comprising a right side crank arm, a right side drive shaft having a forward end and a rearward end, the right side drive shaft coupled to the right side crank arm at the forward end of the right side drive shaft, a right side drive spring coupled to right side drive shaft at the forward end of the right side drive shaft, the right side drive spring circumscribing the right side drive shaft, a right side helical drive adapted so as to allow the rearward end of the right side drive shaft to pass through the right side helical drive, the right side helical drive further adapted to engage right side drive spring, the right side helical drive having a right side helical drive groove, and a right side drive bevel gear circumscribing right side helical drive, the right side drive bevel gear having a right side follower adapted to engage right side helical drive groove, right side drive bevel gear adapted to engage a right side wheel bevel gear, and a wheel coupled to right side wheel bevel gear, such that under rotation of the right side crank arm, a force is imparted to the right side drive shaft and a force is imparted to the right side drive spring, such that right side drive shaft passes through right side helical drive, and right side helical drive is motivated rearwardly by right side drive spring, such that under the rearward movement of right side helical drive, right side helical drive groove imparts a rotational force on right side follower, which imparts a rotational force on right side helical drive gear, which imparts rotational force on right side wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate, the transmission further comprising a left side crank arm, a left side drive shaft having a forward end and a rearward end, the left side drive shaft coupled to the left side crank arm at the forward end of the left side drive shaft, a left side drive spring coupled to left side drive shaft at the forward end of the left side drive shaft, the left side drive spring circumscribing the left side drive shaft, a left side helical drive adapted so as to allow the rearward end of the left side drive shaft to pass through the left side helical drive, the left side helical drive further adapted to engage left side drive spring, the left side helical drive having a left side helical drive groove, and a left side drive bevel gear circumscribing left side helical drive, the left side drive bevel gear having a left side follower adapted to engage left side helical drive groove, left side drive bevel gear adapted to engage a left side wheel bevel gear, and a wheel coupled to left side wheel bevel gear, such that under rotation of the left side crank arm, a force is imparted to the left side drive shaft and a force is imparted to the left side drive spring, such that left side drive shaft passes through left side helical drive, and left side helical drive is motivated rearwardly by left side drive spring, such that under the rearward movement of left side helical drive, left side helical drive groove imparts a rotational force on left side follower, which imparts a rotational force on left side helical drive gear, which imparts rotational force on left side wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate.
17. A bicycle comprising a front wheel, a rear wheel, and a frame, the front wheel rotationally coupled to the frame, the rear wheel rotationally coupled to the frame, the bicycle further comprising a transmission, the transmission comprising a right side crank arm, a right side drive shaft having a forward end and a rearward end, the right side drive shaft coupled to the right side crank arm at the forward end of the right side drive shaft, a right side drive spring coupled to right side drive shaft at the forward end of the right side drive shaft, the right side drive spring circumscribing the right side drive shaft, a right side helical drive adapted so as to allow the rearward end of the right side drive shaft to pass through the right side helical drive, the right side helical drive further adapted to engage right side drive spring, the right side helical drive having a right side helical drive groove, and a right side drive bevel gear circumscribing right side helical drive, the right side drive bevel gear having a right side follower adapted to engage right side helical drive groove, right side drive bevel gear adapted to engage a right side wheel bevel gear, the rear wheel coupled to right side wheel bevel gear, such that under rotation of the right side crank arm, a force is imparted to the right side drive shaft and a force is imparted to the right side drive spring, such that right side drive shaft passes through right side helical drive, and right side helical drive is motivated rearwardly by right side drive spring, such that under the rearward movement of right side helical drive, right side helical drive groove imparts a rotational force on right side follower, which imparts a rotational force on right side helical drive gear, which imparts rotational force on right side wheel bevel gear, which imparts a rotational force on rear wheel such that when the rotational force on rear wheel is sufficient to overcome opposing forces, rear wheel will rotate, the transmission further comprising a left side crank arm, a left side drive shaft having a forward end and a rearward end, the left side drive shaft coupled to the left side crank arm at the forward end of the left side drive shaft, a left side drive spring coupled to left side drive shaft at the forWard end of the left side drive shaft, the left side drive spring circumscribing the left side drive shaft, a left side helical drive adapted so as to allow the rearward end of the left side drive shaft to pass through the left side helical drive, the left side helical drive further adapted to engage left side drive spring, the left side helical drive having a left side helical drive groove, and a left side drive bevel gear circumscribing left side helical drive, the left side drive bevel gear having a left side follower adapted to engage left side helical drive groove, left side drive bevel gear adapted to engage a left side wheel bevel gear, and the rear wheel coupled to left side wheel bevel gear, such that under rotation of the left side crank arm, a force is imparted to the left side drive shaft and a force is imparted to the left side drive spring, such that left side drive shaft passes through left side helical drive, and left side helical drive is motivated rearwardly by left side drive spring, such that under the rearward movement of left side helical drive, left side helical drive groove imparts a rotational force on left side follower, which imparts a rotational force on left side helical drive gear, which imparts rotational force on left side wheel bevel gear, which imparts a rotational force on the rear wheel such that when the rotational force on the rear wheel is sufficient to overcome opposing forces, rear wheel will rotate.
18. A transmission comprising a crank, a drive shaft having a toward end and a rearward end, the drive shaft coupled to the crank at the forward end of the drive shaft, a drive spring coupled to drive shaft at the forward end of the drive shaft, the drive spring circumscribing the drive shaft, a helical drive adapted so as to allow the rearward end of drive shaft to pass through the helical drive, the helical drive further adapted to engage drive spring, the helical drive having a helical drive groove, and a drive bevel gear circumscribing helical drive, the drive bevel gear having a follower adapted to engage helical drive groove, drive bevel gear adapted to engage a wheel bevel gear, and a wheel coupled to wheel bevel gear, such that under rotation of the crank, a force is imparted to the drive shaft arid a force is imparted to the drive spring, such that drive shaft passes through helical drive, and helical drive is motivated forwardly by drive spring, such that under the forward movement of helical drive, helical drive groove imparts a rotational force on follower, which imparts a rotational force on helical drive gear, which imparts rotational force on wheel bevel gear, which imparts a rotational force on wheel such that when the rotational force on wheel is sufficient to overcome opposing forces, wheel will rotate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2801148A CA2801148C (en) | 2013-01-07 | 2013-01-07 | Transmission |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2801148A CA2801148C (en) | 2013-01-07 | 2013-01-07 | Transmission |
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| Publication Number | Publication Date |
|---|---|
| CA2801148A1 CA2801148A1 (en) | 2014-07-07 |
| CA2801148C true CA2801148C (en) | 2019-06-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2801148A Active CA2801148C (en) | 2013-01-07 | 2013-01-07 | Transmission |
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| CA (1) | CA2801148C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110778684A (en) * | 2019-12-10 | 2020-02-11 | 郑福建 | Reducing chain wheel and reducing chain wheel transmission |
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| Publication number | Publication date |
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| CA2801148A1 (en) | 2014-07-07 |
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