GB2397629A

GB2397629A - Clutch input shaft having splines with tapered end portions to aid assembly

Info

Publication number: GB2397629A
Application number: GB0301796A
Authority: GB
Inventors: Anthony Frederick Leaman
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-01-25
Filing date: 2003-01-25
Publication date: 2004-07-28
Also published as: GB0301796D0

Abstract

An engine is provided with a clutch plate 4 which engage with an input shaft 1 of a gearbox via splines 9, 10 which have end portions of tapered or bevelled portions 15 formed by surfaces 16, 17 inclined along the length of the splines 9, 10. During assembly the end portions 15 cause relative rotation between the input shaft 1 and the clutch plate 4 if the splines 9, 10 are misaligned, thereby allowing the splines 9, 10 to be aligned and to mate. The surfaces 16, 17 may be planar or concave or convex.

Description

Quick Assembly Mechanism This invention concerns quick assembly mechanisms

of particular use in the automotive industry and especially but not exclusively for aiding the fitting of gear boxes to motor vehicle engines.

Fitting gear boxes to motor vehicle engines is often difficult because it frequently has to be done in the restricted space of a vehicle engine compartment, this being carried out, for example, when replacing the vehicle clutch mechanism. Not only can there be a space problem, in addition to having to align the bell housing of the clutch mechanism attached to the gear box with the mounting points on the engine, so that they can be bolted together, splines on a splined input shaft of the gear box also have to be aligned with a correspondingly grooved axial hole in the centre of the clutch plate of the clutch mechanism.

Although aligning the bell housing with the mounting points on the engine can generally be effected with relatively little difficulty, as can centring the clutch plate in the clutch assembly with the latter attached to the engine flywheel, - 2 simultaneously aligning the gear box input shaft splines with the grooves in the clutch plate is much more of a problem. In particular, the bell housing generally obscures any view of the mating components, and any difference in the angular alignment between the splines on the gearbox input shaft and the corresponding grooves in the centre of the clutch plate will only become apparent when the two components fail to engage.

Bearing in mind that any clearance between the splines on the input shaft and the grooves in the clutch plate is desirably kept to a minimum, and that the ends of both the splines and the lands between the clutch plate grooves meet substantially parallel to each other, rotation of either of the mating components into the correct position for the splines to slide into the grooves prior to their assembly is essentially hit and miss.

Rotation of either the drive chain through the gearbox or the engine during the assembly process is a possibility for overcoming this problem, but is often impossible for one person to do this whilst at the same time offering up the gearbox to the engine.

According to the present invention there is provided a combination of a gearbox having an input shaft and an internal combustion engine having a clutch plate, the shaft and the plate being mechanically connected by respective splines, the splines of either or both having end portions which cause relative rotation therebetween on axial engagement therebetween during assembly of the combination.

The end portions of the splines which cause said relative rotation preferably have surfaces inclined to the length of the splines. The surfaces can be substantially planar, concave or convex.

Either the input shaft or the clutch plate can have end portions which cause said relative rotation and the splines of the other - 3 of the plate and the shaft has a bevelled end portion substantially perpendicular to the length of the splines thereof. However, it is preferred for both the input shaft and the clutch plate to have end portions which cause said relative rotation.

An embodiment of the present invention will now be described with reference to the accompanying drawings in which: Fig. 1 shows a cut away vertical section through a motor vehicle clutch assembly; Fig. 2 is a cut away diagrammatic view of a prior art splined gearbox input shaft viewed along its axis of rotation and a clutch plate of an internal combustion engine clutch plate mated thereon, both having been flattened out for ease of description; Fig. 3 is identical to Fig. 2 except that the shaft and clutch plate are shown displaced (i.e. rotated) relative to each other prior to mating; and Fig. 4 is a view of a portion of an embodiment of the present invention corresponding to Fig. 1 prior to mating of the parts viewed axially of the gearbox input shaft.

Referring to Fig. 1, a gearbox input shaft 1 has a splined end portion 2 located in a central splined or grooved hole 3 in a clutch plate 4, the plate 4 being held within a conventional clutch assembly 5 attached to an engine flywheel 6. The flywheel 6 is located within a bell housing 7 attached to an internal combustion engine (not shown) by bolts (not shown) screwed into the engine crank case.

The splines on the input shaft 1 and within the hole 3 in the clutch plate 4 are of a generally trapezoidal section viewed radially of the shaft 1, as shown diagramatically in Fig. 2. - 4

The end of the gearbox shaft 1 is bevelled as shown at 8, the splines in the hole 3 of the clutch plate 4 having a complementary bevel which supposedly facilitates insertion of the shaft 1 into the plate 4, but in practice generally does not and is the problem which the present invention overcomes.

The generally tapezoidal shape of the splines 9 on the input shaft 1 and 10 within the centre hole 3 of the clutch plate 4 can be seen from Figs. 2 and 3. The shaft 1 and the plate 4

are shown flattened out for ease of description.

The splines 9 of the shaft 1 define a plurality of grooves 11 therebetween which in use receive complementary splines 10 in the clutch plate 4, and the splines 10 within the plate 4 similarly define a plurality of grooves 13 therebetween which in use receive the splines 9 on the shaft 1.

In order for the splines 9 on the shaft 1 and the splines 10 in the clutch plate 4 to slide past each other to enable the gearbox to be attached to the engine, splines 9 have to be aligned with grooves 13 and splines 10 have to be aligned with grooves 11, as shown in Fig. 2. However, the chances of such alignment being sufficiently accurate to slide these components together are generally low, particularly when there is a close tolerance, i.e. a small clearance, between the respective splines on the shaft 1 and in the plate 4.

Fig. 3 shows the effect of a slight misalignment between the splines 9 and 10 and the grooves 11 and 13 into which they are supposed to slide. The result is that the splines 9 on the shaft 1 collide with the splines 10 in the plate 4, which prevents mating.

The present invention is illustrated with reference to Fig. 4 which again shows the input shaft 1 and clutch plate 4 flattened out, but shows these components viewed radially of both prior to mating and from below as shown in Fig. 2. For ease of

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description the reference numerals used in Figs. 2 and 3 are also used in Fig. 4.

The splines 9 on the shaft 1 project upwardly from the plane of the page, defining grooves 11 therebetween, and the splines 10 in the plate 4 project into the plane of the page, defining grooves 13 therebetween.

The splines 10 each have bevelled front faces 14 which are substantially perpendicular to the lengths of the splines 10 and slope into the hole 3 in the plate 4. In prior art arrangements the splines 9 on the shaft 1 had similar bevels 8 which were also perpendicular to the lengths of the splines 9. The splines 9 shown in Fig. 4, however, have tapered end portions 15 defined by two inclined surfaces 16 and 17.

As will be appreciated by those skilled in the art, pushing shaft 1 and plate 4 of Fig. 4 together to effect mating will result in splines 9 sliding into grooves 13, and splines 10 sliding into grooves 11. However, if the respective sets of splines and grooves are misaligned, for example similarly to Fig. 3, instead of the sliding movement being blocked, one or other of the surfaces 16 and 17 defining the tapered portions 15 of the splines 9 will engage sloping edges 18 or 19 of the splines 10. The result is that the shaft 1 and the plate 4 will be displaced, that is rotated, relative to each other until the splines 9 become aligned with the grooves 13, and the splines 10 become aligned with the grooves 11. The shaft 1 and the plate 4 can then be mated merely by pushing the gearbox and clutch assembly towards the engine, and this can be done without observing the mating components.

As will be appreciated, the shape of the tapered portions 15 of the splines 9 of the shaft 1 can be varied widely provided when they engage the splines 10 in the plate 4, pushing the shaft 1 and the plate 4 together results in relative displacement, i.e..

rotation, therebetween. Thus each spline 9 can have a tapered end portion 15 formed by two inclined surfaces as shown in Fig. 6 - 4, or a single inclined surface, provided the desired rotation between the shaft 1 and the plate 4 is achieved.

As will be appreciated, the splines 10 in the clutch plate 4 can be similarly or alternatively provided with tapered end portions 15, that is the splines of either or both of the input shaft 1 and the clutch plate 4 can be provided with tapered end portions for effecting rotational movement between these components when they are pushed together during their being mated together.

As will also be appreciated, the inclined surfaces 16 and 17 can be substantially planar as shown, or of some other shape provided the required relative rotation between the input shaft 1 and the clutch plate 4 results from pushing these components together. Thus they could be concave or convex. - 7 -

Claims

Claims 1. A combination of a gearbox having an input shaft and an internal

combustion engine having a clutch plate, the shaft and the plate being mechanically connected by respective splines, the splines of either or both having end portions which cause relative rotation therebetween on axial engagement therebetween during assembly of the combination.
2. A combination according to claim 1, wherein the end portions of the splines which cause said relative rotation have surfaces inclined to the length of the splines.
3. A combination according to claim 2, wherein the surfaces are substantially planar.
4. A combination according to claim 2, wherein the surfaces are concave or convex.
5. A combination according to any of the preceding claims, wherein either the shaft or the plate have end portions which cause said relative rotation and the splines of the other of the plate and the shaft has a bevelled end portion substantially perpendicular to the length of the splines thereof.
6. A gearbox having an input shaft with splines which have end portions with at least one surface inclined to the length of the splines said surface causing relative rotation between the input shaft and a clutch plate mounted on a vehicle engine on axial engagement therebetween during assembly of the gearbox on the engine.
7. A gearbox according to claim 6, wherein the at least one surface is as defined in any of claims 2 to 5.
8. A gearbox according to claim 6 or claim 7, wherein each spllne has two of said surfaces. - 8
9. A clutch plate for a vehicle engine, the plate having a splined centre hole, the splines thereof having at least one surface for causing relative rotation between the clutch plate and the input shaft of the engine on axial engagement therebetween during assembly of the gearbox on the engine.
10. A clutch plate according to claim 9, wherein the surface is as defined in any of claims 2 to 5.
11. A clutch plate according to claim 9 or claim 10, wherein each spline has two of said surfaces.
12. A combination of a clutch plate and gearbox substantially as herein described with reference to Fig. 4 of the accompanying drawings.