CA2842126C

CA2842126C - Gear assembly

Info

Publication number: CA2842126C
Application number: CA2842126A
Authority: CA
Inventors: Everett C. Macneil
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-02-07
Filing date: 2014-02-07
Publication date: 2017-01-17
Anticipated expiration: 2034-02-07
Also published as: CA2842126A1

Abstract

A gear assembly is disclosed comprising a cassette, a spring, a hub, and a counterweight wherein the spring is disposed to apply a force to the cassette, and wherein the counterweight is coupled to the cassette so that under rotation of the hub, centripetal acceleration acts on the counterweight so as to apply a force to the cassette, opposed in direction to the spring force, sufficient to overcome at least a portion of the force applied to the cassette by the spring so as to move the cassette in a direction opposed to the direction of the spring force.

Description

=
GEAR ASSEMBLY
BACKGROUND
Technical Field -The present disclosure relates to a gear assembly for cycles.
Description of the Related Art The modern multi-gear bicycle has a chain-ring or sprocket coupled to a crank to be actuated or peddled by a rider. The bicycle will also have a rear wheel sprocket coupled to a rear wheel. A chain is disposed about the chain-ring sprocket and runs from the chain-ring sprocket to the rear-wheel sprocket and returns to the chain ring sprocket, such that the chain circumscribes the pair of the chain-ring sprocket and the rear wheel sprocket.
When the cranks are turned, the chain-ring sprocket rotates, causing the chain to travel along the path circumscribing the pair of the chain-ring sprocket and the rear wheel sprocket. The chain engages both the chain-ring sprocket and the rear wheel sprocket causing rear wheel sprocket and rear wheel to turn under peddling of the crank. Thus a rider peddling the cranks can cause the rear wheel to turn and cause forward motion of the bicycle.
A chain-ring of a particular circumference and rear wheel sprocket with a particular circumference will create a particular gear ratio derived from the ratio of the circumference of the chain-ring sprocket to the circumference of the rear wheel sprocket. Where the chain-ring sprocket has the same circumference as the rear wheel sprocket, the gear ratio will be 1:1 such that one revolution of the cranks will result in one revolution of the rear wheel sprocket and in turn, one revolution of the rear wheel.

it is often advantageous to employ a gear ratio such that one revolution of the chair ring sprocket causes more than one revolution of the rear wheel sprocket.. When a rider wishes to utilize such a gear ratio, a rear wheel sprocket with a smaller circumference than the circumference of the chain-ring may be selected.
Modern bicycles may have multiple different sized chain rings, and multiple different size rear wheel sprockets. The multiple different size rear wheel sprockets on modern bicycles are often fastened together to create a set of sprockets known as a cassette. The larger circumference rear-wheel sprockets are usually disposed towards the inside of the cassette towards the rear wheel and the small circumference rear wheel sprockets are disposed towards the outside of the cassette, away from the rear wheel. To engage a different rear wheel sprocket, to change the gear ratio, a device known as a derailleur is commonly employed. The derailleur operates to pull the chain from one rear sprocket to another, changing the resultant gear ratio.
In Most embodiments, in an unactuated state, the derailleur lines up with the inner, larger circumference rear wheel sprocket. A rider may actuate a lever, for example, to pull a cable connected between the lever and the derailleur.
When the cable is pulled, the derailleur actuates and moves away from the rear wheel and to line up with a smaller circumference rear wheel sprocket. This change in alignment has the effect of pulling the chain from the larger circumference rear wheel sprocket to the smaller circumference rear wheel sprocket. When the rider wishes to move to a small gear ratio, the lever may be actuated by the rider to release the cable. When the tension is released, springs either in the derailleur, lever, or both, return the derailleur to a position lined up with a larger circumference rear wheel sprocket.
This system employed in the prior art has two disadvantages. Firstly, the rider must manually select the gear ratio desired for a particular application.
Secondly, the chain will only operate in a straight line where the chain ring

2 =
sprocket is in line with the rear wheel sprocket and in line with the chain ring.
Utilizing rear wheel sprockets on either side of the line defined by the plane of the chain ring will result in the chain engaging the rear wheel sprocket or chain ring, or both, at an angle. Angled operation will increase wear on the rear wheel sprocket, chain ring, and chain. It is preferable to have the rear wheel sprocket line up with the chain ring in each selected gear ratio.
BRIEF SUMMARY
In one embodiment, a gear assembly is disclosed comprising a cassette, a spring, a hub, and a counterweight wherein the spring is disposed to apply a force to the cassette, and wherein the counterweight is coupled to the cassette so that under rotation of the hub, centripetal acceleration acts on the counterweight so as to apply a force to the cassette, opposed in direction to the spring force, sufficient to overcome at least a portion of the force applied to the cassette by the spring so as to move the cassette in a direction opposed to the direction of the spring force.
In another embodiment, the gear assembly hub has an axis and wherein the spring applies an inwardly force to the cassette along the axis and wherein the force applied by the counterweight is applied to the cassette outwardly along the axis.
In another embodiment, the gear assembly hub has an axis and wherein the spring applies an outwardly force to the cassette along the axis and wherein the force applied by the counterweight is applied to the cassette inwardly along the axis.
In another embodiment, a gear assembly is disclosed comprising a cassette, a spring, a hub, and a shifter, wherein the spring is disposed to apply a force to the casette, and wherein the shifter is coupled to the cassette so that under operation of the shifter a force opposite to the spring force is applied to the

3 cassette sufficient to overcome at least a portion of the spring force applied to cassette so as to result in movement of the cassette.
In another embodiment, the hub has an axis and wherein the spring applies an inwardly force to the cassette along the axis and wherein the force applied by the shifter is applied to the cassette outwardly along the axis.
In another embodiment, hub has an axis and wherein the spring applies an outwardly force to the cassette along the axis and wherein the force applied by the shifter is applied to the cassette inwardly along the axis.
In another embodiment, the counterweight comprises a plurality of counterweights.
In another embodiment, the counterweight is coupled to cassette by a cable.
=
=

4 =

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 side view of a gear assembly according to one embodiment.
Figure 2 is a cross-section of a gear assembly according to one embodiment.
Figure 3 is a top view of a portion of a gear assembly according to one embodiment.
Figure 4 is a cross-section of a gear assembly according to one embodiment.
Figure 5 is a cross-section of a gear assembly according to one embodiment.
Figure 6 is a wheel of a gear assembly according to one embodiment.
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

5 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.
Figure 1 shows portions of a bicycle 60. Bicycle 60 has a crank 70 coupled to a chain-ring sprocket 80. A chain 90 is disposed about the chain-ring sprocket 80. The chain 90 runs from the chain-ring sprocket to cassette 20, cassette 20 being comprised of a plurality of individual rear-wheel sprockets of different diameters, (20A, 20B, 20C, and 200, as shown in Figures 3A and 3B).
Cassette 20 is shown with four rear wheel sprockets (20A, 20B, 20C, and 20D, as shown in Figures 3A and 3B) but may have more, typically eight, nine, ten or eleven rear wheel sprockets, as is known in the art.

6 =

At an initial point, chain 90 will be disposed about the innermost and largest rear wheel sprocket, 20A, comprising cassette 20 and will return to chain ring sprocket 80, such that the chain 90 circumscribes the pair of the chain-ring sprocket 80 and rear wheel sprocket 20A of cassette 20. When the crank 70 is turned, the chain-ring sprocket 80 will rotate, causing chain 90 to travel along the path circumscribing the pair of the chain-ring sprocket 80 and cassette 20.
Chain 90 engages both chain-ring sprocket 80 and cassette 20 causing cassette 20 to turn and causing rear wheel (not shown) to turn as cassette 20 is coupled to rear wheel (not shown). Thus a rider turning the cranks 70 can cause the rear wheel to turn and cause forward motion of the bicycle 60.
A particular chain-ring sprocket 80 with a particular circumference and particular rear wheel sprocket of cassette 20 with a particular circumference will create a particular gear ratio depending on the ratio of the circumference of the chain-ring sprocket 80 to the circumference of the particular rear wheel sprocket of cassette 20. For example, where the chain-ring sprocket 80 has the same circumference as the rear wheel sprocket, the gear ratio will be 1:1 such that one revolution of the cranks will result in one revolution of the rear wheel sprocket and in turn, one revolution of the rear wheel.
It is often advantageous to employ a gear ratio such that one revolution of the chain-ring sprocket 80 causes more than one revolution of the rear wheel sprocket. When a rider wishes to utilize such a gear ratio, a rear wheel sprocket with a smaller circumference than the circumference of the chain-ring may be selected. It is often advantageous to use a particular gear ratio depending on the current speed of the bicycle, the grade of the surface, wind resistance, the rider's strength, as well as other factors. On a particular ride, a rider may wish to change gear ratios multiple times by having the chain 90 to engage a particular sprocket of cassette 20 at various points in a ride.

7 = CA 02842126 2016-07-27 In one embodiment, chain 90 is motivated to engage a particular sprocket of cassette 20 by having cassette 20 move inwardly or outwardly from hub 40. Figure 2 shows a cross-section of gear assembly 10.
When cassette 20 moves inwardly, chain 90 (not shown in Figure 2) will be pulled inwardly, as it is engaged with a sprocket of cassette 20. As cassette 20 continues to move inwardly, chain 90 will no longer align with the current sprocket of cassette 20, but will align with a sprocket of cassette 20 that is of a smaller diameter. When the alignment is sufficiently adjusted through the process of pulling the cassette 20 inwardly, chain 90 will jump from the larger diameter sprocket of cassette 20 to a smaller diameter sprocket of cassette 20.
When chain 90 jumps from the larger diameter sprocket of cassette 20 to a smaller diameter sprocket of cassette 20, the gear ratio will be adjusted.
When cassette 20 moves outwardly, chain 90 will be pulled outwardly as it is engaged.with a sprocket of cassette 20. As cassette 20 continues to move outwardly, chain 90 will no longer align with the current sprocket of cassette 20, but will align with a sprocket of cassette 20 that is of a larger diameter.
When the alignment is sufficiently adjusted through the process of pulling the cassette outwardly, chain 90 will jump from the smaller diameter sprocket of cassette 20 to a larger diameter sprocket of cassette 20. When chain 90 jumps from the smaller diameter sprocket of cassette 20 to a larger diameter sprocket of cassette 20, the gear ratio will be adjusted.
Figures 3A and 3B shows the process of chain 90 jumping from one rear wheel sprocket to another. In Figure 3A, cassette 20 is extended outwardly so that chain 90 runs from chain-ring sprocket 80 is aligned with the innermost sprocket 20A. In Figure 3B, cassette 20 is pulled inwardly so that chain 90 is aligned with the outermost sprocket 20D. As cassette 20 moves inwardly or outwardly, chain 90 will best align with a particular sprocket and as cassette 20 is moved, chain 90 will jump to the most aligned sprocket.

8 As chain 90 moves from a larger diameter rear wheel sprocket to a smaller diameter rear wheel sprocket, the chain length required to circumscribe the chain-ring sprocket and the rear wheel sprocket will be reduced. As is shown in Figure 1, a tensioner 92 may be employed to take up the slack in chain 90. A
chain tensioner such as the AlfineTM tensioner from Shimano Corp. or the 02 Chain Tension MasterTM tensioner from Q2 Bike Parts of Rancho Dominguez, CA, USA may be employed. The tensioner may be located proximate to gear assembly 10, or may be located proximate to chain ring sprocket 80, where it would remain in-line with chain-ring sprocket 80.
Figure 2 shows a cross-section of gear assembly 10. Figure 2 shows cassette 20,a spring 30, a hub 40 having an axis 40A, and a counterweight 50.
In this embodiment, spring 30 is disposed within hub 40, but may be located elsewhere to provide force to cassette 20. Spring 30 is abutted or fixed at an end away from cassette 20 and is situated to apply an outwardly force against he cassette 20 along the direction of the axis of hub 40. Spring 30 may be disposed within hub 40 against a stop (not shown) or other element rather or may be fixed to hub 40, such that spring 30 is disposed as to apply an outwardly force against cassette 20. =
Hub 40 may be the hub of a rear wheel of a bicycle (rear wheel of bicycle not shown in Figure 2). Under rotation of the rear wheel (not shown) rotatable hub 40 will rotate in kind. The rotational motion will induce a centripetal acceleration. In one embodiment, counterweight 50 is positioned so that under rotation of hub 40, counterweight 50 moves under the induced centripetal acceleration. Counterweight 50 is coupled to cassette 20, in one embodiment, buy a cable 50A, such that under movement of the counterweight 50, under centripetal acceleration induced by movement of the rear wheel, cassette 20 is pulled inwardly. The manner of coupling counterweight 50 to cassette 20 may be selected by a person of ordinary skill in the art. As counterweight 50 moves under the induced centripetal acceleration, counterweight 50 will, by virtue of being

9 coupled to cassette 20, impart an inwardly force cassette 20. In total, there is outwardly force imparted to the cassette 20 by spring 30 and an inwardly force imparted by counterweight 50, when the hub 40 is rotating. The net force will cause cassette 20 to move inwardly or outwardly as the case may be, depending on the net force.
In Figure 2 two counterweights 50 are shown, although any number may be selected by a person of ordinary skill in the art for a particular application, depending on the spring weight, and other factors, for example. When the rear wheel (not shown) is at rest, counterweights will not be affected by centripetal acceleration and will be in the position shown by the solid lines, as spring 30 will impart a force to push cassette 20 outwardly, dragging counterweights 50 with it by virtue of the coupling between counterweights 50 and cassettes 20. As rear wheel (not shown) is rotating, counterweights 50 will rotate and under the centripetal acceleration, will be pulled outwardly towards the position shown in Figure 2 by the dashed lines. Counterweights 50 are coupled to cassette 20 by a cable 50A, in this embodiment, and when counterweights 50 move outwardly, the cable is drawn by counterweights 50 so as to pull inwardly on cassette 20.
Counterweights 50 may be coupled to cassette 20 via a cable 102 and pulleys 104. The faster the rotation, the greater the centripetal acceleration. With greater centripetal acceleration, counterweights 50 move outwardly to the position indicated by the.dashed lines. As counterweights 50 move outwardly, more force inward force imparted on cassette 20 inwardly. When the inward force imparted on cassette 20 by counterweights 50 is greater than the force of spring 30, cassette 20 will move inwardly. Chain 90 will jump from a larger diameter sprocket, such as 20A to a smaller diameter sprocket, such as 20B, as is demonstrated in Figure 3.
When the rotation slows, the centripetal acceleration will be reduced and less inward force will be imparted on cassette 20. When the inwardly force imparted on cassette 20 is less than the outwardly force of spring 30, cassette 20 will move outwardly. Chain 90 will jump from a smaller diameter sprocket, such as 20B to a larger diameter sprocket, such as 20A, as is demonstrated in Figures and 3B.
Counterweight 50 may be a single counterweight, or may be a plurality of counterweights. Counterweights may be hinged elements as is shown in Figure 2. Counterweights 50 could be weights that slide on spokes of a conventionally spoke laced bicycle wheel, or upon specially configured spokes or sliding members. Figure 6 shows a bicycle wheel 110 with cassette 20 and counterweights 50 (only one counterweight called out in Figure 6). The number and placement of counterweights 50 can be done to maximize even weight distribution, although this is not required.
To. assist with chain 90 jumping between rear wheel sprockets of cassette 20, individual rear wheel sprockets may employ ramps or pins, as is known in the art and rear wheel sprockets of cassette 20 may be offset, as is also known in the art, such as employed in the HyperglideTM cassette commercially available from Shimano Corp., Irvine California In another embodiment, cassette 20 may be pulled inwardly by a cable actuated by a rider. Levers actuating cables, or shifters, are known in the art and include those commercially available from Shimano Corp., Irvine California, and Sram Corporation, Chicago, Illinois. Figure 4 shows such an embodiment.
Figure 4 shows shifter 100 connected by a cable to 102 that is run around pulley 104A and 104B to impart a force pulling cassette 20 inwardly. In Figure 4, cable 102 is actuated by shifter 100. Cable may be pulled about pulley 104A through the interior of hub 40, around pulley 104B to cassette 20. As shifter is actuated to pull cable 102, cassette 20 is pulled inwardly.
In another embodiment, spring 30 may impart a pulling force to pull cassette 20 inwardly. In such an embodiment, pulley 104B and the cable routing shown in Figure 4 can be replaced where cable 102 is pulled directly on cassette 20, about pulley 104, outwardly.
= 11 Shifting may be indexed at the shifter by means known in the art including those commercially available from Shimano Corp., Irvine California, and Sram Corporation, Chicago, Illinois. Shifting may be indexed at the cassette 20 by, for example, a ball plunger, such as those commercially available from CarrLane Manufacturing Co., St. Louis MO, USA. Figure 5 shows ball plunger 106 and associated depressions 108 for receiving ball of ball plunger 106.
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. In such embodiments, hub 40 may preferably be a freewheel or ratqheting hub so that chain 90 may stop movement and allow wheel to continue to turn, for when a rider is coasting down a hill, for example.
Further, the disclosed embodiments could be implemented in motorized machines as well.
When used with a motorized machine, hub 40 may preferably not be of a freewheel or ratcheting variety and may preferably be fixed to wheel 110.
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.
=

Claims

1. A gear assembly comprising a cassette, a spring, a hub, and a counterweight wherein the spring is disposed to apply a force to the cassette, and wherein the counterweight is coupled to the cassette so that under rotation of the hub, centripetal acceleration acts on the counterweight so as to apply a force to the cassette, opposed in direction to the spring force, sufficient to overcome at least a portion of the force applied to the cassette by the spring so as to move the cassette in a direction opposed to the direction of the spring force.

2. The gear assembly of claim 1 wherein the hub has an axis and wherein the spring applies an inwardly force to the cassette along the axis and wherein the force applied by the counterweight is applied to the cassette outwardly along the axis.

3. The gear assembly of claim 1 wherein the hub has an axis and wherein the spring applies an outwardly force to the cassette along the axis and wherein the force applied by the counterweight is applied to the cassette inwardly along the axis.

4. The gear assembly of claim 1 wherein the hub has an axis and wherein the spring applies an outwardly force to the cassette along the axis and wherein the force applied by the shifter is applied to the cassette inwardly along the axis.

5. The gear assembly of claim 1 wherein counterweight comprises a plurality of counterweights.

6. The gear assembly of claim 1 wherein counterweight Is coupled to cassette by a cable.