Metal working – Means to assemble or disassemble – Including means to relatively position plural work parts
Reexamination Certificate
2000-11-10
2001-12-25
Watson, Robert C. (Department: 3723)
Metal working
Means to assemble or disassemble
Including means to relatively position plural work parts
C029S271000
Reexamination Certificate
active
06332256
ABSTRACT:
BACKGROUND TO THE INVENTION
1. Field of the 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, such camshafts being driven in timed relation to the engine crankshaft by a toothed drive belt (timing belt) entrained around toothed pulleys or sprockets (herein called sprockets) on the shafts. With the aim of preventing failure in service and possible consequential engine damage, service schedules usually specify belt replacement at predetermined time and/or mileage intervals, and to ensure that the timing relationship between the cam shafts and the crankshaft of the engine is not lost the camshafts may have to be held against rotation relative to one another while the old belt is removed and a new one fitted. Other rotary elements driven by the timing belt may also have to be held against rotation during the replacement operation, for example if an engine is a compression-ignition engine and there is a fuel injection pump whose timed driving is effected by the belt.
Service tools for effecting such holding of the camshafts and/or other rotary elements of engines are available, but as supplied by motor manufacturers they are usually specifically designed for one engine or family of engines and are not usable for other engines. If a service establishment wishes to perform such work on many different engines but does not wish to keep a large number of special tools, there is a requirement for a more versatile holding device which is capable of being used on a wide range of engines. One problem in the design of such a more versatile holding device is that drive sprockets might be very close together, with very little space between them in which any part of a holding device can be disposed.
SUMMARY OF THE INVENTION
It is broadly the object of the present invention to provide a holding device in which the above requirement and problem are addressed.
According to the present invention, we provide a device for holding a rotaiy element stationary against rotation relative to another rotary element adjacent thereto, comprising first, second, third and fourth holding members engagable each with one or other of the rotary elements; connecting means connecting said holding members to one another and providing for adjustment of at least three of said holding members relative to one another; and means for fixing said holding members in set positions relative to one another.
Preferably all the holding members are adjustable relative to one another.
In a device according to the invention, the ability of the holding members to be adjusted relative to one another means that the device is usable in a number of different situations, i.e. in different engines.
Preferably each holding member is adapted to engage with the periphery of a sprocket, constituting a said rotary element, with which a timing belt cooperates. To this end each holding member preferably comprises a formation which cooperates with one or more teeth of a sprocket, e.g. a protuberance which is able to extend radially inwardly relative to the sprocket into the space between adjacent teeth.
In one of the embodiments described hereafter, each holding member further comprises an arcuate or generally arcuate wall portion which is able to lie against the crests of a number of teeth, with a protuberance extending radially inwardly from the wall portion and able to fit between two adjacent such teeth.
Preferably the holding members are arranged with the first and second holding members adjustable relative to one another in respect of their position and/or orientation and the third and fourth holding members adjustable relative to one another in respect of their position and/or orientation, the connecting means providing for adjustment of said first and second holding members together, in position and orientation, relative to said third and fourth holding members together.
The connecting means preferably comprises an elongate connecting member relative to which said first and second holding members are together movable angularly whilst said third and fourth holding members are together movable angularly and lengthwise thereof.
The means for fixing the holding members in set positions relative to the connecting means preferably comprises clamping means. Each clamping means may comprise a screw member having threaded engagement with a holding member and passing through an opening in the elongate connecting member, with the connecting member being arranged to be clamped between a head of the screw member and the holding member when the screw is tightened.
Each such screw member may effect clamping of both the first and second or the third and fourth holding members as the case may be together to the connecting means, or may clamp only one holding member relative to the connecting member while the respective associated holding member is separately clamped to the aforesaid holding member, e.g. by a further screw member.
In use, the first and second holding members may be engaged one with one sprocket and the other with the other sprocket, at adjacent peripheral regions thereof outwardly of the narrowest part of the space therebetween, whilst the third and fourth holding members are likewise engaged with the two sprockets, but outwardly of the space therebetween in the opposite direction. In this case the connecting member may extend generally chordally or tangentially of the two sprockets or one of them.
In another embodiment of the holding device described hereafter, the first and second holding members may be engaged in use with spaced parts of the periphery of one of the sprockets while the third and fourth holding members are engaged with spaced parts of the periphery of the other sprocket. Viewed parallel to the axes of rotation of the sprockets, the connecting member then extends generally transversely across the gap between the peripheries of the sprockets.
In either event, the arrangement of the holding members means that there need be nothing in the narrowest part of the space between the sprockets so that the device can be used if the sprockets are very close together or if there is an engine part between them, e.g. a casting rib. The connecting means can be arranged to be spaced from the plane of the end faces of the sprockets.
REFERENCES:
patent: 4684357 (1987-08-01), Hooper
patent: 5490582 (1996-02-01), Trowbridge
patent: 5755029 (1998-05-01), Learned
patent: 5950294 (1999-09-01), Gibbs
patent: 6058585 (2000-05-01), Soleymani
patent: 2340539A (2000-02-01), None
Auto Service Tools Limited
MacMillan Sobanski & Todd LLC
Watson Robert C.
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