GB2340539A

GB2340539A - Device for holding rotary elements, eg engine timing belt sprockets, against rotation

Info

Publication number: GB2340539A
Application number: GB9817434A
Authority: GB
Inventors: Malcolm Bruce Dawson
Original assignee: Auto Service Tools Ltd
Current assignee: Auto Service Tools Ltd
Priority date: 1998-08-12
Filing date: 1998-08-12
Publication date: 2000-02-23
Anticipated expiration: 2018-08-12
Also published as: GB2340539B; GB9817434D0

Abstract

Sprockets or toothed pulleys 10, 11, which may be on the camshafts of a dohc engine or on a camshaft and on a fuel injection pump, respectively, of a compression-ignition engine, are held in fixed angular relationship by a device having two holders 12, 13 adjustably mounted on a connecting member 14 and able to be fixed in position by clamps 15, 16. Each holder 12, 13 has an arcuate wall 17, 22 which lies close to the crests of the teeth of the respective sprocket 10, 11 and ridges 19, 20 for engaging the hollow between adjacent teeth. Holder 12 also has a flange 21 with a slot 25 by which the holder 12 can be bolted to an adjacent engine part so that holder 12 may be used by itself to hold a single sprocket against rotation.

Description

234053,9 PATENTS ACT 1977 GMD/A9561GB Title: HOLDING DEVICE

Description of Invention

This invention relates to a device for holding two rotary elements, disposed alongside one another, stationary relative to one another.

The invention has been devised for the purpose of holding stationary relative to one another the camshafts of a double overhead camshaft internal combustion engine, or a camshaft and a fuel injection pump driving shaft of an engine, e.g. in a motor vehicle. Modem engines cornmonly have their valves operated by one or more overhead camshafts, and the usual, or at least most common, method by which such camshafts are driven in timed relation to the engine crankshaft is by the use of a toothed drive belt (timing belt). The belt is entrained around toothed pulleys or sprockets (herein called sprockets) on the driving and driven parts. Such a belt is an efficient means of driving a camshaft, being relatively inexpensive, light in weight, and quiet in operation, 0 and is r eadily able to follow a serpentine path so as to be able to drive not only a camshaft or camshafts and a fuel injection pump in the case of a compressionignition engine, but also other rotary ancillary devices such as for example a water pump.

Such timing belts do not, liosever, last indefinitely and if failure should occur while an engine is running extremely extensive engine damage can occur.

0 0 C1 Therefore the service schedules of such engines usually specify belt 0 replacement at pre-determined time and/or mileage intervals. To ensure that 0 the timing relationship between the canishaft(s), the fuel injection pump if present, and the crankshaft of the engine is not lost, the usual technique employed in timing belt replacement is to hold the camshaft(s) against rotation c 2 whilst an old belt is removed and a new one fitted. Accordingly there is a requirement for a device for effecting such locking or holding.

Motor manufacturers usually sell service tools for this purpose to their authorised dealers. Such tools are usually specifically designed for one particular engine or family of engines and are not usable for other engines. There are, however, many service establishments which carry out work on many different engines from different manufacturers, and for such establishments or for individual mechanics to have a whole range of holding devices to suit all engines upon which work. is likely to be required to be performed would be prohibitively inconvenient and expensive.

Accordingly it is the object of the present invention to provide a holding device for the purpose above set forth which is usable for a wide range of different engines.

According to the invention, we provide a device for holding a rotary element stationary against rotation relative to another rotary element or a fixed element, comprising two holding members respectively engagable with the first said rotary element and another rotary element adjacent thereto, a connecting member relative to which both said holding members are movable angularly 0 and at least one is movable linearly, whereby said holding members are adjustable both in orientation relative to one another and distance from one another, and ineans for fixing said liolding members in set positions relative to 'd connectii. member.

sai 1 0 Preferably each holdirig member is adapted to eii(,aoe with the periphery, C 0 t> of a sprocket with which a tliiiiiig belt cooperates. To this end each holding member preferably comprises aii arcuate.\,all portion which in use lies against pail of the outer periphery of such a sprocket and at least one formation which cooperates with the teeth to prevent rotation of the sprocket.

Preferably each holding member comprises two of said formations in the forin of protuberances extending from said arcuate wall portion each to engage between adjacent teeth on the sprocket.

Preferably said means for fixing said holding members in set positions relative to said connecting member comprises respective clamping means for each of said members. Each such clamping means may comprise a screw member having threaded engagement with the holding member and passing through an opening in the connecting member, with the connecting member being arranged to be clamped between a head part of the screw and the holding 0 member when the screw is tightened.

To provide for the aforesaid adjustment of said holding members relative to the connecting member, the latter may have an aperture through which the screw of the clamping means of one of the holding members passes and a slot 0 extending lengthwise of the connecting member through which the screw of the 0 clamping means of the other holding member passes.

At least one of the holding members is preferably completely detachable from the connecting member, e.g. by complete removal of the screw of the clamping means, and the, each, or one of the detachable holding members may 0 have a formation whereby it rnay be fixed to a stationary engine part. By virtue of this provision, one of the holding members of the device according to the 0 invention may be used for holding stationary a single rotary element such as a 0 camshaft drive sprocket, without holding such element stationary relative to 0 another adjacent rotary element.

The iii.,,eiitioii will now be described by way of example with reference to the accompanying drawing, which is a perspective view of a holding device 0 In in accordance with the invention in use.

Referring to the drawing, two adjacent rotary elements in the form of sprockets or toothed pulleys foi- engagement by a toothed timing belt (not 0 '1 shown) are indicated at 10, 11. These sprockets may be on the end of the 4 camshaft of a double overhead camshaft internal combustion engine, or on a camshaft and a fuel injection pump of a compression ignition engine.

The rotary elements 10, 11 are held against rotation relative to one another by a holding device which comprises two holding members 12, 13, a connecting member 14, and respective clamping means 15, 16 by which the holding members are secured to the connecting member.

The holding member 12 comprises an arcuate wall portion 17, whose curvature is such that the wall portion is able to lie closely against the crests of the teeth on the sprocket 11, and at or adjacent each end of the arcuate wall portion 17 there is a respective protruding, ridge formation 19, 20 which is able to enter the hollow between two adjacent teeth. Not all sprockets used on internal combustion engines are the same size as one another, but there is a high degree of similarity and the tooth spacing also is similar as between different engines: thus the holding member is able to engage in such manner 0 C zy with a sprocket on a large range of engines. Along one edge of the arcuate wall 0 c portion 17 the holding member has a flange portion 21 which extends away 0 from the sprocket with which the holding inember engages: at one end of the CI holding member such flange is of relatively large dimension, while at the other Z end of the holding member such flaii,,e is smaller.

The holding inernber 133 is almost identical to the holding member 12 and its arcuate wall portion is indicated at 22: Its relatively sinall flange at one end is indicated at 23) and the increased size of such flange at the other end is Z:> indicated at 24. The holding nierriber 12 differs from the holding member H) in c C that the flange portion 21 of the holding member 12 has, at its larger end, a slot 0 0 extending into it, whilst the holding nieniber 13) has no such slot (although it may be provided with such a slot if required, to avoid having to manufacture two different components).

The coruiecting member 14 comprises a strip of material with, at one end, an aperture not shown and at the other end ari elongate longitudinally extending slot 26.

The clamping means 15 is a known device, comprising a screw whose head is indicated at 27 and whose threaded shank passes through the aperture at the respective end of the connecting member 14 and engages with a screwthreaded bore in the flange part 21 of the holding member 12. The screw is 0 able to be turned by a manually engagable lever 28 which is able to be de- clutched from the head 27 of the screw by pulling the lever axially of the screw upwardly from the head. Such de-clutching action enables the screw to be tightened or loosened in increments of rotation if due to obstruction by the other clamping means 16 or by other adjacent components in use of the device the lever is not able to be turned through a complete revolution.

The clamping means 16 is identical to the clamping means 15, except the screw shank passes through the slot 26 in the connecting member 14. By tightening the clamping means 15, 16, the two holding members 12, 13 are able to be fixed in required positions relative to the connecting member.

The possible movement of the holding members relative to the connectina meniber is angular and, in the case of the holding member 13, additionally linear. This enables the holding members to be set relative to one another to be able to engage, and hold against rotation relative to one another, rotary elements such as the sprockets 10, 11 of a wide range of spacings C 0 relative to one another. It will be appreciated that in internal combustion engines the timing belt might follow aii extremely serpentine path and there 1 C may be obstructions to the positioning of a holding device in certain areas.

However, the ranae of adjustability of the positions of the holding devices 0 C provided by the arrangement above described enables the holding device to have very wide application to a large range of engines.

0 C 6 The holding members are each detachable from the connecting member, and the holding member 12 may be used by itself'to hold a single rotary element against rotation. This is a requirement on some engines and for this purpose the holding member 12 may be bolted to an adjacent engine part by a bolt passing through the slot 25 in the flange 21 of the holding member.

The invention thus provides an extremely versatile holding device which is convenient to use.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any

C:1 combination of such features, be utilised for realising the invention in diverse forms thereof 7

Claims

1. A device for holdincy a rotary element stationary against rotation relative to c 0 another rotary element or a fixed element, comprising two holding members respectively engagable with the first said rotary element and another rotary element adjacent thereto, a conilectlii,,:,, member relative to which both said holding members are movable angularly and at least one is movable linearly, whereby said holding members are adjustable both in orientation relative to one another and distance from one another, and means for fixing said holding members in set positions relative to said connecting member.

2. A device according to Claim 1,,llereiii each holding member is adapted to engage with a periphery of a sprocket with which a tirning belt cooperates.

J1 A device accoi-duig to Claim 2,,vlierein each holding member comprises an arcuate wall portion which in use lies against pail of the outer periphery of a said sprocket, and at least one forination which cooperates with the teeth of the sprocket to preveiit rotation thereof.

4. A device according to Claim 3) wherein each holding member comprises two of said formations, spaced alom, said arcuate wall portion.

5. A device according to any oiie of the preceding claims wherein said means 0 c) for fixing said holding members in said positioils relative to said connecting 0 C member comprises respective claniping, means for each of said members.

0 8

6. A device according to 'Claim 5 wherein each said clamping means compnses a screw meiriber having threaded engagenientwith the holding member, and passing through an opening in the connecting member whereby the connecting member may be clamped between a head pail of the screw and the holding member upon fightening of the screw.

7. A device according to Claim 6 wherein the connecting member comprises an aperture througr,,h which the screw of one of the clamping means passes and a slot extending lengthwise of the connecting inember through which the screw of the other clamping means passes.

8. A device according to any one of the preceding claims wherein at least one of the holding members is completely detachable frorn the connecting member.

9. A device according to Claim 8 wherein the, each, or one of the detachable holding members is provided with a formation whereby it may be fixed to a 0 stationary engine part.

0

10. A device substantially as hereinbefore described with reference to the accompanying drawings.

Z:1

9. A device according to Clann 8 wherein the, each, or one of the detachable holding members is provided with a formation whereby it may be fixed to a stationary engine part.

11. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.

0 In Amendments to the claims have been riled as follows A device for holding a rotary element stationary against rotation relative to another rotary element adjacent thereto, comprising two holding members respectively engagable with the first said rotary element and the other rotary element, a connecting member relative to which both said holding members are movable angularly and at least one is movable linearly, whereby said holding members are adjustable both in orientation relative to one another and distance from one another, and means for fixing said holding members in set positions relative to said connecting member.

2. A device according to Claim 1 wherein each holding member is adapted to engage with a periphery of a sprocket with which a timing belt cooperates.

3. A device according to Claim 2 wherein each holding member comprises 0 an arcuate wall portion which in use lies against part of the outer periphery of a said sprocket and at least one formation which cooperates With the teeth of the sprocket to prevent rotation thereof.

4. A device according to Claim 3 wherein each holding member comprises two of said formations, spaced along said arcuate wall portion.

5. A device according to any one of the preceding claims wherein said means for fixing said holding members in said positions relative to said connecting member comprises respective clamping means for each of said members.

6. A device according to Claim 5 wherein each said clamping means comprises a screw member having threaded engagement with the holding member, and passing through an opening in the connecting member whereby the connecting member may be clamped between a head part of the screw and the holding member upon tightening of die screw.

7. A device according to Claim 6 wherein the connecting member comprises an aperture through which the screw of one of the clamping means passes and a slot extending, lengthwise of the connecting member through which the screw of the other clamping means passes.

8. A device according to any one of the preceding claims wherein at least one of the holding members is completely detachable from the connecting member.