GB2214609A

GB2214609A - Drive coupling

Info

Publication number: GB2214609A
Application number: GB8801229A
Authority: GB
Inventors: Dhirendra Damji
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1988-01-20
Filing date: 1988-01-20
Publication date: 1989-09-06
Anticipated expiration: 2008-01-20
Also published as: GB8801229D0; GB2214609B

Abstract

A coupling for rotational drive between two rotatable members (11, 13), comprising a first coupling member mounted on one (11) of the two rotatable members and comprising a splined shaft (10), and a second coupling member 12 adapted to receive in driving engagement the first coupling member, the second coupling member 12 being mounted on the other rotatable member (13) and including a plurality of spline-engaging members (17). The ends (16 or 19) of either or both of the splines (14) of the splined shaft (10) and the spine-engaging members (17) are tapered or chamfered so as to cause relative rotational movement between the coupling members on coupling them together when they are not angularly aligned. At least one of the coupling members (12) is mounted (18, 20, 21) for limited rotational movement relative to its rotatable member (13). <IMAGE>

Description

Drive Coupling This invention relates to a drive coupling for coupling a rotational drive between two rotatable members, and is of the kind which comprises a first coupling member mounted on one of the two rotatable members and comprising a splined shaft, and a second coupling member adapted to receive in driving engagement the first coupling member, the second coupling member being mounted on the other rotatable member and including a plurality of spline-engaging members, the ends of either or both of the splines of the splined shaft and the spline-engaging members being tapered or chamfered so as to cause relative rotational movement between the coupling members on coupling them together when they are not angularly aligned.

Drive couplings having a splined shaft portion at the end of a first shaft and a socket adapted to receive the splined portion are well known, for example in motor cars. The ends of the splines of the splined shaft portion are often tapered or chamfered to facilitate engagment of the two parts during coupling. Such couplings are also used in xerographic copying machines, to facilitate assembly during manufacture, and dismantling and reassembly during servicing.

Xerographic copying machines, especially the smaller, lower copy volume machines, may use a xerographic cassette in which some or most of the elements required to carry out the xerographic process are contained. For example, such a cassette may contain a photoreceptor, a charge corotron, a developing device, a transfer corotron, and a cleaning device. The cassette may be inserted into, and removed from, the main body of a xerographic copying apparatus when it is desired to use different coloured toner, or when a cassette is exhausted or otherwise needs replacement. In order to drive some of the elements described, rotational drive may be coupled into the cassette through drive couplings using the splined shaft arrangement outlined above.

There is, however, a problem of shaft alignment as the cassette is introduced into the main body of the machine. If the shafts or other rotational members to be connected are rotationally misaligned during insertion of the cassette, it may be difficult or impossible to make the connection. Tapered or chamfered ends of the splined shaft portion or the splineengaging members of the socket may alleviate this problem to some extent, but difficulties may still occur in cases of rotational misalignment of the coupling parts. The present invention is intended to overcome these difficulties, and accordingly provides a drive coupling of the kind specified which is characterised in that at least one of the coupling members is mounted for limited rotational movement relative to its rotatable member.

The limited rotational movement permitted between a coupling member and its associated rotatable member may be such as to allow engagement of the two parts of the coupling whatever their relative initial angular positions. This is a particularly important advantage in the situation where a xerographic cassette is inserted into and removed from a copying machine, because proper driving engagement will always be made, allowing for rapid and easy changing of cassettes.

A drive coupling in accordance with the invention will now be described1 by way of example, with reference to the accompanying drawings, in which: Figure f is a perspective view of the component parts of a first embodiment of the coupling, and Figure 2 is a perspective view of the major components of a second embodiment of the coupling.

Referring to Figure 1, a splined end portion 10 of the shaft 11 is adapted to engage in a socket member 12 that is mounted on a shaft 13. The splined end portion 10 is in the form of four axially extending splines 14 spaced equally around a central shaft portion 15, the end 16 of each spline being tapered almost to a point on the central shaft portion 15.

The socket member 12 is of substantially cruciform cross section, with four axially extending spline-engaging members 17 adapted to slidingly engage in the spaces between the splines 14 of splined end portion 10. The spline-engaging members 17 extend from one end of a shaft receiving sleeve 18, each spline-engaging member 17 being accommodated by, but not touching, the inside walls of the four arms of the cruciform part of the socket 12. The spline-engaging members 17, the sleeve 18, and the cruciform portion of the socket are all formed integrally, for example as a plastics moulding. The spline-engaging members 17 are of generally rectangular cross section, but their inward facing edges are rounded to facilitate smooth engagement with the splines 14.The leading ends 19 of the spline-engaging members, i.e. their ends remote from sleeve 18, are tapered to facilitate initial engagement of the two parts of the coupling.

Near the end of the sleeve 18 remote from the socket 12, a slot 20 is formed in its wall. A screw 21 passes through the slot 20, and its threaded end portion 22 engages a threaded hole 23 which opens into a flat 24 on the shaft 13. The portion 25 of the screw member nearest its head is unthreaded, and is slightly smaller in diameter than the width of the slot 20. The internal diameter of sleeve 18 is such that it is a loose sliding fit over the shaft 13, so that the sleeve 18 (and hence socket 12) can rotate relative to the shaft 13 to an extent dictated by the circumferential extent of the slot 20.

In the embodiment shown, the drive shaft 13 is always driven in the same direction, so that the screw 21 is always urged into engagement with one end of slot 20. The tapered ends 19 of the spline-engaging members 17 are tapered in such a direction that any rotational misalignment between the splines 14 and the spaces between the spline-engaging members 17 may be taken up by rotation of socket 12 about shaft 13, to the required extent, limited by the length of slot 20. The direction of taper of the ends 19 of members 17 is chosen to accommodate rotational movement of the slot 20 past the screw 21 so that the screw 21 approaches the other end of the slot 20.

In a second embodiment of the invention, shown in Figure 2, the spline portion 10 at the end of shaft 11 is substantially the same as in the Figure 1 embodiment. The socket 32 is, however, somewhat simplified compared with the socket 12 of Figure 1. In other respects, the sleeve 18 and slot 20 correspond with those of Figure 1, as do the shaft and screw (not shown in Figure 2, but corresponding with shaft 13 and screw 21 of Figure 1).

The socket 32 of Figure 2 includes four spline-engaging members 37 which extend from the end wall 40 of sleeve 18, and join the inner surface 41 of an annular collar 42. The ends 39 of the spline-engaging members 37 furthest from sleeve 18 are tapered to ensure rotational alignment as the parts are coupled together.

In either of the embodiments described, either part of the coupling may be the driving part, with the other part being driven. In an alternative form of the invention, not shown, a slotted sleeve like the sleeve 18 may be provided behind the splined portion 10 of shaft 11 instead of, or in addition to, that shown in the drawings behind the socket 12 or 32.

Furthermore, for cases when drive may take place in either rotational sense, end portions of the spline-engaging members 17 or 37 may have double tapers. In any of these alternative embodiments, the length of the slot 20 may be chosen to provide an approriate amount of angular movement to accommodate any amount of rotational misalignment of the shafts.

Claims

Claims:

1. Drive coupling for coupling a rotational drive between two rotatable members, and comprising a first coupling member mounted on one of the two rotatable members and comprising a splined shaft, and a second coupling member adapted to receive in driving engagement the first coupling member, the second coupling member being mounted on the other rotatable member and including a plurality of spline-engaging members, the ends of either or both of the splines of the splined shaft and the spline-engaging members being tapered or chamfered so as to cause relative rotational movement between the coupling members on coupling them together when they are not angularly aligned, characterised in that at least one of the coupling members is mounted for limited rotational movement relative to its rotatable member.

2. A xerographic copying machine including a xerographic cassette for insertion into, and removal from, the main body of the machine, the machine and the cassette being provided respectively with coupling members comprising a drive coupling according to claim 1.