Classifications

• • 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
  • B62M9/00—Transmissions characterised by use of an endless chain, belt, or the like
  • B62M9/04—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio
  • B62M9/06—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio using a single chain, belt, or the like
  • B62M9/08—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio using a single chain, belt, or the like involving eccentrically- mounted or elliptically-shaped driving or driven wheel; with expansible driving or driven wheel

Definitions

• the present invention relates generally to the field of bicycle transmissions, and more particularly, relates to an automatic bicycle transmission wherein the gear ratio can be automatically varied in response to the power requirements.
• Bicycle transmissions wherein the gear ratio can be automatically varied through a contractible and expandable sprocket wheel construction in response to the effort exerted upon the pedals by the cyclist are known, as ex plified by U.S. Patent No. 3,995,508.
• the effective diameter of the sprocket wheel assembly can be varied by changing the radial positions of a plurality of cooperating sprocket gears.
• the determination of the radial positions of the sprocket gears is a function of the imput torque so that by increasing the torque, the effective diameter of the sprocket wheel components will be decreased.
• a continuously acting spring functions to automatically increase the effective diameter of the sprocket gears.
• the present invention relates generally to the field of automatic bicycle transmissions, and more particularly, is directed to an improved expanding sprocket assembly featuring sprocket which are capable of automatic chain engagement without clatter and which are arranged for automatic locking within any predetermined gear ratio.
• the present invention includes a reference wheel of fixed diameter which is arranged for rotation upon a hub which is carried on the pedal shaft and is rotated when the associated pedal arm is rotated.
• the reference wheel includes a pair of radial slots in substantially axial alignment with the pedal arm and a second pair of radial slots which extend at substantially right angles to the pedal arm.
• a small diameter jLink wheel is coaxially connected for rotative movement - /
• a plurality of pivotal links interconnect the outer periphery of the small diameter link wheel and the reference wheel at the respective slots thereof.
• a pair of semi-circular, arcuately formed, drive sprockets oppositely ride within the pedal arm aligned slots in the reference wheel and pair of intermediate chain slides oppositely ride within the ninety degree, angularly offset slots in the reference wheel to comprise an expandable and collapsible drive wheel.
• a compression spring is carried upon the pedal arm to bias a power link to rotate the small diameter wheel in a direction to continuously urge the plurality of links to tend to pull the drive sprockets and chain-slides to their outermost or largest diameter positions.
• the plurality of drive sprockets and chain slides tend to automatically collapse to override the bias of. the spring and to change the gear ratio as may be necessary to most efficiently proceed under the particular local road conditions.
• the aligned and. right angled orientation of the collapsing drive sprockets and chain slides relative to the reference wheel allows conscious, automatic locking of the drive sprockets in any torque adjusted radial position and prevents the collapse of the effective drive wheel diameter upon release of torque on the pedal arm, until such time as the expansion is desired by the cyclist.
• the operator can rotate the pedals to an expansion permitting orientation whereat the compression springs will be free to bias the drive sprockets and chain slides to their respective, expanded positions. In this manner, collapsing and expanding of the effective drive diameter of the drive sprockets or drive wheel can be completely controlled by adjusting the angular orientation of the pedal arms.
• It is another of object of the present invention to provide a novel automatic bicycle transmission including a reference wheel, a plurality of radially movable and rotatable arcuate drive * sprockets, a plurality of radially movable and rotatable arcuate chain slides, means to reduce the diametrical distances between the respective drive sprockets and respective chain slides in response to the application of torque, means to continuously bias the drive sprockets and the chain slides to their radially expanded positions.
• ⁇ VIFO for alternate contact and release of a bicycle drive chain, means to urge the drive sprockets together to decrease the diametrical spacing upon the application of increased torque, continuous means tending to bias the drive sprockets diametrically apart and means to automatically engage a bicycle drive chain with the teeth of the drive sprockets without clatter in any diametrically oriented position.
• Fig. 1 is side elevational view of an automatic bicycle transmission in accordance with the present invention, partially broken away to expose interior construction details.
• Fig..2 is a partial, cross-sectional view taken along line 2-2 on Fig. i; showing particularly the pedal arm construction, with the power compensating link partially broken away for purposes of clarity.
• Fig. 3 is a schematic representation of the position of the drive sprockets and chain slide segments in an expanded, locked condition.
• Fig. 4 is a view similar to Fig. 3, showing the drive sprockets still in locked condition when rotated through forty-five degrees from the position of Fig. 3.
• Fig. 5 is a schematic representation, showing the position of the drive sprockets and chain slide segments in a contracted, unlocked condition, and rotated through ninety degrees from the position of Fig. 4.
• Fig. 6 is view similar to Fig. 5, showing the position of the drive sprockets and chain slide segments at the beginning of a locked condition, and rotated through forty-five degrees from the position of Fig. 5.
• Fig. 7 is a view similar to Fig. 3, showing the position of the drive sprockets and chain slide segments at the end of an expanded, locked condition, and rotated through ninety degrees from the position illustrated in Fig. 6.
• Fig. 8 is an enlarged, partial, diagrammatic view showing the position of initial drive chain engagement on a drive sprocket.
• Fig. 9 is view similar to Fig. 8 showing a second possible position of initial drive chain engagement on a drive sprocket.
• Fig. 10 is an exploded, perspective view of the automatic bicycle transmission of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
• FIG. 1 and 2 there is illustrated in Figs. 1 and 2 an automatic bicycle transmission generally designated 10 comprising a drive pedal arm 12 which is affixed in known manner to rotate the pedal crank 14 for chain drive purposes.
• a central hub 15 is securely affixed to the crank 14 for simultaneous rotation when the crank, is rotated in known manner, for example, by employing a suitable bolt 23 and nut 25.
• the link wheel 18 is freely rotatable about the central hub 15 at the bearing 20 to apply link imposed, radially inwardly directed and radially outwardly directed forces upon the drive sprockets 78, .80 and the chain slides 84, 86 in the manner hereinafter more fully set forth.
• a sprocket adjusting wheel or reference wheel 22 is secured to the central hub 15 by the threaded nut 16 whereby the sprocket adjusting wheel 22 is rotated as the central hub 15 is rotated by the pedal arm 12 for chain drive purposes.
• the sprocket adjusting wheel 22 comprises a first pair of radially oriented slots 24, 26 in longitudinal alignment with the pedal 'arm 12 and second pair of radially oriented slots 28, 30, which slots are positioned at ninety degrees from the axis of the pedal arm 12.
• a plurality of openings 32 may be provided in the sprocket adjusting wheel 22 for weight reducing purposes, in known manner.
• a plurality of pivotal links or arms 36, 38, 40, 42 interconnect the link wheel 18 with the sprocket adjusting wheel 22. for automatic gear ratio adjustment purposes, as hereinafter more fully set forth.
• Each link or arm 36, 38, 40, 42 has its inner end pivotally connected to the link wheel 18 in a respective pivotal connection 44, 46, 48, 50 whereby each of the links is freely pivotal relative to the link wheel 18.
• Each of the links or arms 36, 38, 40, 42 has its other end or outer end indirectly, pivotally connnected by a respective ..outer pivot pin 52, 54, 56, 58 to the sprocket adjusting wheel 22.
• Each of the outer pivot pins 52, 54, 56, 58 respectively is affixed to one of four slide blocks 60, which blocks are preferably rectangular in configuration for linear sliding engagment within one of the longitudinally aligned slots 24, ' 26 or one of the perpendicularly aligned slots 28, 30.
• the pedal arm 12 is equipped with a coil spring 62 which preferably surrounds the pedal arm and biases between an adjusting collar 64 and an L-shaped actuator lug 66.
• the adjusting collar 64 is threadedly engaged upon the exteriorly threaded section 68 at the base of the pedal arm 12 for threaded adjustable movement thereupon.
• a plurality of adjusting openings 70 may be provided in the periphery of the collar in known manner to facilitate rotation of the collar 64 upon the threads 68 when it is desired to adjust spring tension.
• the spring 62 functions to continually bias the actuator lug 66 toward its outermost position away from the crank 14 along the pedal arm 12.
• the actuator lug 66 pivotally connects to one end of a power compensating link 72 at the pivot pin 97.
• OMPI insert 99 cooperates with the end of the pedal arm 12 to prevent rotation of the actuator lug 66 relative to the pedal arm.
• the other end of the power compensating link 72 is pivotally interconnected with the link wheel 18 by the pivot pin 76.
• the pivot pin 76 is circularly offset from radial alignment with the outer pivot pin 97 by approximately five degrees to ten degrees whereby the bias of the spring 62, working through the lug 66, continously tends to pull .the link wheel 18 in a clockwise direction about the pedal crank 14.
• the bearing 20 functions to facilitate rotative movement of the link wheel 18 about the pedal crank 14 and relative to the sprocket adjusting wheel 22.
• a pair of diametrically opposed, arcuate, sprocket segments 7,8, 80 radially reciprocate on their respective slide blocks 60 in diametrically opposed, longitudinal alignment with the pedal arm 12.
• Circularly intermediate the " sprocket segments 78, 80 are positioned a pair of diametrically opposed, radially adjustable chain slide segments 84, 86.
• the chain slide segments 84, 86 are similarly secured to slide blocks 60, which blocks are radially reciprocal within the perpendicularly aligned slots 28, 30.
• pairs of sprocket segments 78, 80 and chain slide segments 84, 86 are movable in automatic response to the torque applied at the pedal 88 within their respective radial slots between' a first, large diameter, low power circle 98 (Figs. 3, 4 and 7) and a collapsed, small diameter, high power circle 100, as shown i.n Figs. 5 and 6.
• Figs. 3-7 wherein schematic views illustrate the interaction of the parts.
• the sprocket segments 78, 80 and chain slides 84, 86 are shown in their expanded or low power circle 98 orientation with the
• OMPI leading tooth 102 of the sprocket segment 78 engaged in a link of the drive chain 82.
• the leading tooth 112 of the diametrically opposed sprocket segment 80 also engages a link of the chain 82.
• the engagement ,of the teeth of the diametrically opposed sprocket segments 78, 80 with spaced links of the drive chain 82 locks the system against further radial expansion or contraction. While sprockets 78, 80 are . illustrated in low power circle orientation, it will be appreciated that the same locked condition between the sprocket segments 78, 80 and the chain 82 will apply for all gear ratio radial adjusted positions of the sprockets, from the full expanded orientation of Fig. 3 to the complete collapsed, high power cycle position 100 of Fig. 5.
• the system will be locked against radially outward expansion or radially inward, contraction whenever the teeth of both sprocket segments 78, 80 are engaged upon portions of the chain 82 as illustrated in Figs. 3, 4, 6 and 7. Collapsing of the plurality of sprocket segments 78, 80 and chain slide segments 82, 84 can only occur when radially inwardly directed forces of sufficient magnitude to overcome the bias of the spring 62, as the pedal arm 12 is moved from the position illustrated in Fig. 4 towards the position of the parts illustrated in Fig. 6 are applied.
• any required compensation in the length of chain 82 will be automatically adjusted by a spring biased derailleur (not shown) in the well known, usual manner.
• a spring biased derailleur (not shown) in the well known, usual manner.
• Figs. 8 and 9 the timing of the chain 82 automatically to a sprocket segment 78 is illustrated. As shown, it will be appreciated that the distance between the central axes of adjacent chain rollers 118, 118* will be exactly equal to the distance between adjacent segment teeth 120, 122 measured along approximately the pitch circle of the sprocket segment 78 to facilitate full engagement of the sprocket teeth with the chain rollers in well known manner.
• the distance between the centers of adjacent chain rollers 118, 118' will be less than the circular distance between the centers of adjacent segment teeth 120, 122 measured- at the respective outer faces 128 thereof.
• the differences in the diameter measured at the respective pitch circle 116 of the sprocket segments and the tooth face circle 128 of the sprocket segments functions to cause the chain to automatically and smoothly fall into the grooves 124 defined between adjacent segment teeth 120, 122 in a smooth, chatter-free engagement.
• FIG. 9 One possible initial engagement between the leading sprocket tooth 102 and a . chain roller 118 or 118' is illustrated in Fig. 9 wherein initial contact is made upon the outer face 128 of the tooth 122 by the middle of a chain roller 118, 118'. Because the distance between centers of adjacent chain rollers 118, 118' will be less than the distance between the faces of adjacent segment teeth 120, 122 measured at the face circle 128, as above set forth, then the next trailing chain roller 118' will position slightly forwardly of the rearwardly adjacent sprocket tooth 102*.
• next trailing roller 118" of the chain 82 will engage the next rearwardly adjacent tooth 102" partially upon the forward face 130 whereby the rollers 118, 118", 118" will automatically be pulled downwardly into the respective grooves 124 between adjacent segment teeth in an automatic, smooth manner.
• the sprocket segments ,78, 80 are fabricated as portions of a circle and the respective differences in the diameter between the pitch circle ⁇ of a sprocket and the face circle of the sprocket functions automatically to cause the chain rollers 118, 118', 118" to fall into the sprocket grooves 124 for smooth chain engagement.
• the initial contact between the leading sprocket tooth 102 and the chain roller 118 is on the forward surface or leading face 130 of the face of the tooth 102 as illustrated. Accordingly, the next trailing roller 118* will engage the forward face of the rearwardly adjacent sprocket tooth 122' inasmuch as the distance between the adjacent rollers 118, 118* is less than the distance between the adjacent teeth 102, 122* when measured at the face circle 128.
• next reawardly spaced roller 118" will be caused to engage the next rearwardly adjacent tooth 102" more forwardly and closer to the root of the groove 124 between adjacent teeth whereby all of the rollers 118, 118', 118" will automatically and freely seat directly within respectively adjacent sprocket teeth grooves 124.
• the teeth 102, 120', 122 of a sprocket segment 78 engage adjacent rollers 118, 118*, 118" of the chain 82 smoothly and automatically and the rollers automatically fall into the sprocket grooves 124 without chatter regardless of the orientation of the initial contact between a chain roller and the leading sprocket segment 102.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Transmissions By Endless Flexible Members (AREA)
• Gears, Cams (AREA)
• Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=23175946

Family Applications (1)

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• 1982
  • 1982-09-20 JP JP50305682A patent/JPS58501713A/ja active Pending
  • 1982-09-20 BR BR8207881A patent/BR8207881A/pt unknown
  • 1982-09-20 AU AU89929/82A patent/AU8992982A/en not_active Abandoned
  • 1982-09-20 EP EP19820903106 patent/EP0088798A1/de not_active Withdrawn
  • 1982-09-20 WO PCT/US1982/001271 patent/WO1983001098A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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