GB2456505A

GB2456505A - A delayed lock up/freewheel bearing

Info

Publication number: GB2456505A
Application number: GB0800545A
Authority: GB
Inventors: Malcolm Tomlinson
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-01-14
Filing date: 2008-01-14
Publication date: 2009-07-22
Also published as: GB0800545D0

Abstract

A bearing which introduces a delay into the lock up path, typically half a revolution, such that any unintentional minor reversal from the freewheel or normally counterclockwise direction can be tolerated without triggering an unwanted response. The delayed lock up is preferably achieved by circumferentially separating the outer ring 3, 4 and interposing an additional outboard element 3, 4 into the lock up path with the additional outboard element being connected to the bearing output ring. The delay preferably operates in both the lock up and free wheel directions and the arrangement is particularly suited for use in a bicycle stabilizer arrangement.

Description

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2456505

Delayed lock up / freewheel bearing.

This invention relates to trapped roller freewheel / lock up type bearings

These assemblies are constructed with a ball race bearing in parallel with a ramp and roller type lock up clutch on shared inner and outer rings.

These bearings normally lock up immediately the direction of rotation reverses from the freewheeling mode. However, this invention relates to a modification whereby the lock up can be delayed up to (say) a half turn which is a highly desirable feature for the deployment unit of a bicycle stabilizer described in patent GB 2 406 082 A.

Specifically, it allows the cyclist to reverse the pedals for half a turn before rotating the crank sited deployment unit cam, thereby deploying or retracting the stabilizer. This prevents accidental deployment when, for example, reverse pedalling to set the pedals horizontally when the cyclist is freewheeling downhill; and unintentional retraction when pumping pedals (forwards and backwards) during very low speed operation when the stabilizer is deployed. It also facilitates automatic stowage of the stabilizer (by virtue of a rat trap return spring) with minimal reverse pedalling beyond release from the deployed detent.

The delayed lock up is achieved by adding a further ring into the lock up path to facilitate the construction of 3 chambers, each of which confines a ball bearing which abuts the chamber ends at the delay extremes

The invention will now be described solely by way of example with reference to the accompanying drawings in which'

Figure 1 shows the standard clutch freewheel

Figure 2 shows the introduction of the delay feature

Figure 3 shows the invention incorporated into a bicycle stabilizer deployment unit.

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Figure 4 shows a schematic highlighting the stabilizer deployment unit.

In figure 1, anticlockwise (ACW) rotation of the inner ring 5, relative to the outer ring 1, allows freewheeling Clockwise (CW) rotation allows small springs to wedge the rollers 6, between the ramps 5a, and outer ring 1, thereby producing lock up

Fig.2, and fig 3 show the invention in that:

The outer ring 1, has been separated into the clutch portion 2 and the ballrace portion 3 An additional ring 4, has been added outboard o/the clutch outer ring 2 This additional ring 4, is rigidly fixed to, or part of, the roller bearing outer ring 3. For compactness, the large diameter cam bearing inner race 7, might also be part of this arrangement.

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The separated clutch outer ring 2, and the added outboard ring 4, each have 3 equally spaced but opposed cut aways 2a, and 4a, such that when assembled, 3 circumferential chambers are formed each of which contains a tracked ball bearing 8, thereby giving axial location to the clutch outer ring 2, to prevent axial float and contact with adjacent elements which might inhibit priming the delay, e.g. as might occur with (non tracked) rollers

Forward pedalling will rotate the inner ring of the clutch 5, ACW, which wants to overrun its outer ring 2, but the drag of the baulked clutch rollers 6, is imparted to the clutch outer ring 2, and first primes the delay by rolling each of the three chamber ball bearings 8, until they abut opposing ends of the inner and outer cut aways, 2a and 4a, (as shown) at which point the clutch overruns as without the modifications.

Reverse pedalling rotates the inner ring CW and immediately locks up the clutch but it takes (say) half a revolution to roll the three chamber ball bearings 8, to abut the opposite extremes of the cut aways 2a, 4a, which then locks the whole bearing assembly and rotates the cam 7, to deploy or retract the stabilizer and engage detents 9, 10, in the groove 11, at top and bottom dead centre (TDC and BDC) to hold these positions

By using tracked ball bearings 8, it not only provides axial location to the clutch outer ring 2, but operates similar to an epicyclic gear whereby the aggregate delay, e.g. half a turn, is the sum of the subtended angles of each outer and each inner cut outs 4a, 2a, after taking account of the ball bearing contact diameters. It also gives minimal resistance to rotation and thus primes the delay before the clutch overruns.

To facilitate manufacture, the tracks 12 , 13, may be continuous through the baulks 14, 15; only the ball 8, contacts with the remaining walls providing the baulking force.

The 3 locking balls should provide sufficient lock up torque without brinelling since there is virtually no impact loading in this application, only progressive deployment loading and detent loads. Even so, any brinelling would not inhibit function and would be self limiting This application might also permit reducing the number of lock up rollers and ramps (to say 3 ) to reduce overrun drag to an absolute minimum and possibly facilitate assembly of the three chamber ball bearings 8

Claims

Claims. 1 A bearing with a directional freewheeling / lockup facility whereby locking is delayed by (say) half a revolution. 2. A bearing as in claim 1, in which the delayed lockup is achieved by circumferentially separating the outer ring and interposing an additional outboard element into the lockup path with said element being reconnected to the bearing output ring 3 A bearing as in claim 2, in which a multiplicity of chambers formed by the lockup outer ring and the added element, in combination with a trapped and tracked ball bearing in each chamber, provides the delay feature by travelling between extremities of the formed chamber to abut the opposite extremities 4. A bearing as in claim 3, whereby the delay operates in both the lock up and the freewheel directions. 5. A bearing as in claim 3, wherein the trapped ball race tracks may be continuous with the tracked ball abutment occurring at the the inner edges of the parted baulk walls. Amendments to the claims have been filed as follows Claims.

1. A bearing with a directional freewheeling / lockup facility whereby locking is delayed by (say) half a revolution.

2. A bearing as in claim 1, in which the delayed lockup is achieved by circumferentially separating the outer ring and interposing an additional outboard element into the lockup path with said element being reconnected to the bearing output ring.

3. A bearing as in claim 2, in which a multiplicity of chambers formed by the lockup outer ring and the added element, in combination with a trapped and tracked ball bearing in each chamber, provides the delay feature by travelling between extremities of the formed chamber to abut the opposite extremities.

4. A bearing as in claim 3, whereby the delay operates in both the lock up and the freewheel directions.

5. A bearing as in claim 3, wherein the trapped ball race tracks may be continuous with the tracked ball abutment occurring at the the inner edges of the parted baulk walls.

6. A bearing assembly as in claims 1 to 5, wherein a larger diameter bearing inner ring is fixed eccentrically outboard of the bearing output ring and the larger diameter bearing outer ring is fixed to a perimeter housing to produce a desired displacement when the housing rotation is constrained.

7. A bearing assembly as in claim 6 wherein sprung detents in the outer housing engage grooves in the outer bearing inner ring or inner ring housing to arrest rotation at desired extremes of displacement.

8. A bearing assembly as in claim 7 wherein the axes of the detents in the outer housing may be inclined towards the approaching grooves in the lock up mode to reduce side friction of the detent balls into detent and resist detent escape through any torque load in the freewheel direction.