GB2183796A - Stepwise release means for indexing mechanisms and controls embodying the same - Google Patents

Abstract

A stepwise release mechanism for the indexing mechanism of a bicycle or like trigger control comprises an indexing wheel (11) for rotatable mounting in the control, first and second parallel arrays (33,34) of detent formations provided at respective opposite faces of the indexing wheel at the periphery thereof, and a manually actuable release member (36) cooperable with both said arrays (33,34), the release member (36) being such as to be cooperably engaged with one or other of the detent formations at all times, thus to ensure incremental return movement of the indexing wheel under the effect of resilient return means applied thereto. <IMAGE>

Description

SPECIFICATION Stepwise release means for indexing mechanism and controls embodying the same The invention concerns indexing mechanisms, and has more particular reference to a stepwise release means for use in connection therewith. A particular application for the release means of the invention is in the context of an indexing mechanism for use in gear selection means for bicycle and like hubs.

The object of the invention is to provide a release means for the indexing mechanism of a gear selection means for controlling the setting of a bicycle or like multi-speed hub.

According to the present invention there is proposed a stepwise release means for the indexing mechanism of a bicycle or like change speed gear trigger control, which indexing mechanism includes an indexing body adjustable in increments in a first direction against resilient restraint means, the release means comprising plural arrays of detent formations arranged in adjacent parallel disposition on the indexing body, at least one of the individual detents of one array being in laterally offset disposition in relation to the corresponding detent of another array, a release member, spaced lugs on the release member, each for selective cooperation with a respective one of the said arrays and a restraint means resiliently resisting motion of the release member.

The invention will now be described further, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a first form of trigger control for a bicycle or like multi speed hub embodying the release means of the invention; Fig. 2 is an underside plan view of the arrangement shown in Fig.1, parts having been removed in the interests of clarity; Fig. 3 is a scrap view, drawn to a larger scale, of a part of the structure shown in Fig.

2; and Figs.4 and 4a are a diagrammatic perspective view and a corresponding scrap view of the return mechanism of the arrangement shown in Figs. 1 and 2.

Referring now to the drawings, and in particular to Figs. 1 to 4 thereof, a trigger mechanism for the linear adjustment of the control cable of a bicycle or like three-speed hub comprises an indexing wheel 11 rotatably mounted in a generally rectangular casing 12 and having an aperture 13 and slot 14 therein to receive the nipple 15 and the end region 16, respectively, of the control cable 17. An elongate carrier plate 18 is mounted coaxially with the wheel for angular adjustment relative thereto, the plate extending beyond the periphery of the wheel and pivotally supporting an indexing member 19 at its remote end and as an extension thereto.Drive formations 21, 22 are provided on the periphery of the indexing wheel 11 for selective engagement by a cooperable drive formation 23 on indexing member 19, for use in effecting angular displacement of the indexing wheel against the restraint of a return spring 24 connected between such wheel and the casing 12, all in a manner hereafter to be disclosed.

The mechanism further includes a second return spring 25 between the carrier plate 18 and the casing, the spring 25 resisting motion of the carrier plate 18 in an adjustment direction of the mechanism.

Drive formations 21,22 comprise contact surfaces arranged in angularly spaced radial disposition at the periphery of the indexing wheel 11, whilst cooperable drive formation 23 comprises a nose extending from the indexing member 19 in the peripheral direction of the indexing wheel 11 and in closely spaced opposed relationship thereto. A fixed abutment member 26 is provided at one end of a slot 27 in the side wall of the casing 30 through which the indexing member extends, the slot extending through approximately 1100.

or arc. Member 26 is positioned adjacent the periphery of the indexing wheel 11 and at that side of the indexing member 19 remote from drive formation 23, member 26 being at the same or a similar radial distance from the axis of the carrier plate 18 as is a pivot pin 28 which secures the indexing member 19 to the indexing wheel 11. Return spring 25 operates to return the carrier plate 18 to a datum position defined by abutment member 26 after displacement from such position.

The operation of the mechanism thus far described is such that on movement of indexing member 19 in the direction of arrow A in Fig. 2, such member pivots in ciockwise direction about pin 28 and thus moves the nose which defines drive formation 23 towards to the periphery of the indexing wheel.

Continued such pivotal motion of the indexing member 19 will bring drive formation 23 into contact with the periphery of indexing wheel 11, thus preventing further relative pivotal motion between indexing member 19 and carrier plate 18. Continued movement of the indexing member 19 will cause the carrier plate 18 and indexing member 19 to move in unison about the centre of the indexing wheel and against the restraint of return spring 25 to bring drive formation 23 into full depth engagement with the contact surface which constitutes drive formation 22. Still further angular movement of indexing member 19 in an appropriate amount will move the indexing wheel 11 against the restraint of spring 24 and will thus shift the control cable 17 longitudinally to effect the necessary gear adjustment.

The indexing wheel will be automatically retained in its adjusted position by suitable means hereafter to be described, and the indexing member 19 and carrier plate 18 will be returned to an initial position in contact with abutment 26 by return spring 25.

The relative disposition of parts shown in Fig. 2 is consistent with the selection of the intermediate gear of the three-speed hub to which cable 17 is connected, adjustment to such position from low gear having previously been effected by engagement of drive formation 23 with drive formation 21 and rotational adjustment of the indexing wheel 11 by movement of indexing member 19 in like manner to that previously described.

It will be apparent from the drawing that initial pivotal motion of the indexing member about pin 28 will initiate movement of the carrier plate 18 by reaction between abutment 26 and that part of the indexing member adjacent thereto, but the primary movement at this stage is the relative pivotal movement between the carrier plate and indexing member such as brings drive formation 23 into position for engagement with drive formation 21 or 22.

The geometry of the structure is such that a lost motion exists as between movement of the nose, or drive formation, 23 of the indexing member and its engagement with the cooperating drive formations 21, 22.

Retention of the indexing wheel in an adjusted position and its selective release from such position is effected by a stepwise release means 32.

The structure as aforesaid is described and claimed in our copending British Patent Application No. 8432714 (Specification GB.2169065A).

In accordance with the invention, and referring now to Figs 4 and 4a, the stepwise release means 32 comprises upper and lower arrays 33, 34 of detent formations at an edge 35 of the indexing wheel 11 and a springloaded release member 36 bridging said edge and having opposed, inwardly facing ratchets 37,38 each for selective engagement with a respective one of the said arrays.

The upper array 33 of detent formations comprises a cut-away 39 in the peripheral region of the indexing wheel 11 and a radial ratchet tooth 41 intermediate the angular extent of such region, the ratchet tooth 41 having an upright front operating face 42 and an inclined rear or camming face 43. A further operating face 44 is provided in the cut-away region 39 at that side of the ratchet tooth 41 remote from the upright operating face 42 thereof.

The lower array 34 comprises a further cutaway 45 in the periphery of the indexing wheel 11, such further cut-away being of similar, though slightly greater, arcuate extent to region 39 and in angular alignment therewith.

Two ratchet teeth 46, 47 are provided in cutaway 45, such teeth having respective upright radial operating faces 48, 49 and respective rear camming faces 51,52. A further upright radial operation face 53 is provided at that end of cut-away 45 remote from operating face 48, face 53 being in angularly offset disposition relative to operating face 44 of array 33.

Operating face 42 of ratchet tooth 41 lies intermediate faces 48, 49 of teeth 46, 47 in the peripheral direction of the indexing wheel, whilst the ends of the cut-aways 39,45 remote from operating faces 44,53 respectively are in axial alignment.

Release member 36 consists of a generally rectangular body 54 having a quadrant shaped cut-out 50 in the wall thereof of a radius corresponding to that of the indexing wheel 11, the vertical extent of the cut out being such as freely to receive the periphery of the wheel 11 into engagement therewith. The underside of the body 54 is formed with a step at 55 at that corner thereof diagonally opposite cut out 50 to provide a seating for a return spring 56, the top of the body being stepped to define a peripheral shoulder 57 to engage the underside of the top 58 of the casing 30 within which the mechanism is housed, there being an aperture 59 in such casing through which the reduced dimension part 61 of the top of the body extends.

Ratchets 37, 38 extend inwardly of the body from the upper and lower surfaces of the cut-out 50 therein, said ratchets being in alignment and being directed radially of such cut out. The adjacent parallel edges 62,63 of ratchets 37, 38 are separated by a distance in excess of the thickness of the indexing wheel in the region of aligned cut aways 39, 45 but less than such thickness plus the height of the ratchet teeth 41, 46, 47.

In the assembled condition of the trigger mechanism body 54 is engaged with the periphery of the indexing wheel 11 with ratchets 37, 38 in position for engagement with the upper and lower arrays 33, 34 respectively.

In use, and with release member 36 loaded outwardly of the casing 30 by return spring 56, ratchet 38 is engaged with the lower array of detent formations at an angular position therein appropriate to the gear selection as determined by the last operation of indexing member 19, being held in surface contact with the relevant radial operating face 48, 49, 53 by return spring 24 acting on the indexing wheel. It is to be observed that, in the use condition of the mechanism, cable tension serves also to urge ratchet 38 into surface contact with the relevant operating face, and the primary purpose of return spring 24 is to position indexing wheel 11 prior to cable fitment.

Assuming the ratchet 38 to be engaged with radial operating face 48, movement of the release member 36 against the restraint of return spring 56 will move the ratchet 38 across face 48 and out of engagement therewith, the indexing wheel thus being free to rotate under the effect of return spring 24 or the tension in cable 17 when fitted. However, as ratchet 38 moves out of engagerhent with the lower array 34, the opposing ratchet 37 moves into the path of movement of radial operating face 42 of the upper array 33, thus limiting the range of angular movement of the indexing wheel. On release of member 36, such member moves upwardly under the effect of return spring 56, ratchet 37 disengaging from operating face 42 but ratchet 38 moving into the path of movement of operating face 49 to prevent further angular movement of the indexing wheel.

On a subsequent actuation of the release member 36, ratchet 38 is brought into engagement with radial face 53 in analogous manner.

Thus it will be seen that gear adjustment in either sense can be effected, adjustment in one direction being controlled by operation of indexing member 19 and in the other direction by operation of release member 36, the adjustment in each case being an increment appropriate to the extent of longitudinal displacement of the control cable necessary to shift the moving parts of the change speed gear hub a relevant amount.

The invention is not restricted to the embodiment hereinbefore described, since alternatives will readily present themselves to one skilled in the art.

Thus, for example, whilst the stepwise release means hereinproposed is disclosed specifically in the context of trigger controls for such as bicycle 3 or 5-speed change-gear hubs, such means may well be of advantageous application in connection with multispeed gear hubs having other than 3 or 5 gear selections or indeed in other contexts.

Furthermore, the release means is not limited to arrangements wherein the indexing is along an arcuate path, since modifications will readily present themselves to one skilled in the art such as would render the same of application to linear indexing.

Claims (6)

1. A stepwise release means for the indexing mechanism of a bicycle or like change speed gear trigger control, which indexing mechanism includes an indexing body adjustable in increments in a first direction against resilient restraint means, the release means comprising plural arrays of detent formations arranged in adjacent parallel dispositions on the indexing body, at least one of the individual detents of one array being in laterally offset disposition in relation to the corresponding detent of another array, a release member, spaced lugs on the release member, each for selective cooperation with a respective one of the said arrays and a restraint means resisting motion to the release member.

2. Stepwise release means as claimed in claim 1, wherein the release member is manually actuable in a direction transverse to the said first direction, the spaced lugs on the release member being such that at all times one at least thereof is cooperatively engageable with its respective detent formations.

3. Stepwise release means as claimed in claim 1 or 2, wherein each array is of arcuate form, the arrays being provided at opposite faces of an indexing body adjustable about an axis remote from said arrays.

4. Stepwise release means as claimed in claim 3, wherein the indexing body comprises an indexing wheel and the plural arrays of detent formations are provided at respective opposite faces and at the periphery thereof, the release member being movable in a direction parallel to the axis of the indexing wheel.

5. Stepwise release means as claimed in any one of the preceding claims, wherein each detent formation includes an upstanding ratchet tooth, the upstanding teeth in the respective detent formations being in offset disposition and each upstanding tooth having an upright, operating front face and an inclined camming rear face.

6. A stepwise release means for the indexing mechanism of a bicycle or like change speed gear trigger control, substantially as hereinbefore described with reference to and as illustrated in Figs. 4 and 4a of the accompanying drawings.