GB2309947A

GB2309947A - Vehicle suspension

Info

Publication number: GB2309947A
Application number: GB9602558A
Authority: GB
Inventors: Timothy Peter Bailey; David Wallace
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1996-02-08
Filing date: 1996-02-08
Publication date: 1997-08-13
Anticipated expiration: 2016-02-08
Also published as: GB2309947B; GB9602558D0

Abstract

A vehicle suspension comprises a wheel mounting member 10 and an upwardly extending strut 34, such as a MacPherson strut. The strut 34 has a lower end 35 connected to the wheel mounting member 10 and an upper end connected, in use, to a body or chassis of the vehicle. The connection between the wheel mounting member 10 and the strut 34 comprises a tapered surface 86 on the strut 34 which locates a complementary shaped tapered surface 80 on the wheel mounting member 10 so as to position the strut 34 and wheel mounting member 10 correctly relative to each other. A screw-threaded fastener arrangement 96, 98 at the bottom of the strut 34 holds the located strut 34 and wheel mounting member 10 together.

Description

A VEHICLE SUSPENSION The invention relates to a vehicle suspension of the kind comprising a wheel mounting member and an upwardly extending strut, the strut having a lower end connected to the wheel mounting member and an upper end connected, in use, to the body or chassis of the vehicle. The strut is typically in the form of a McPherson strut.

Suspensions of the above kind have been known for many years and an example of part of such a suspension is shown in Figs 1 and 2 of the accompanying drawings. The suspension comprises a wheel mounting member 10 mounted for pivoting about a steering axis A on one end of a suspension arm 12. The other end of the suspension arm 12 is connected to a body 14 of the vehicle for pivoting upwardly or downwardly about an axis B. The wheel mounting member 10 includes a steering arm 18 which is connected to a track rod 20 in known manner. The wheel mounting member 10 has an upper limb 22 having a boss 24 at its free end. The boss 24 is formed with a cylindrical opening 26 and is also formed with a vertical split 28. Figure 2 is a view of the free end of the limb 22 looking in the direction of arrow II in Fig 2. It will be noted that the boss 24 has two spaced apart lugs 30 thereon arranged one each side of the split 28. The lugs 30 are formed with holes 31 through which a pinch bolt 32 can be passed. An upwardly extending strut 34 is provided. The strut 34 has a lower end 35 positioned within the opening 26 and its upper end is connected to part of the vehicle body 14 via a rotary bearing 36 through which the steering axis A passes. The lower end 35 of the strut 34 is clamped within the opening 26 by means of the pinch bolt 32 and a nut 33. It will be noted that the strut 34 is of a McPherson type comprising a damper 38 and suspension spring 40. The spring 40 is arranged between a spring plate 42 on the damper and an upper spring plate 44 which reacts against the body 14.

During assembly of a vehicle, it is commonplace to bring the body and the suspension together. Normally, the McPherson Strut 34 will be carried by its upper end on the body 14 and will hang freely downwards. When the body is lowered on to the suspension, it is necessary to insert the lower end 35 of the strut 34 manually into the opening 26 and then, finally, tighten the pinch bolt 32. It is necessary for the opening 26 to be machined so that its diameter will match very closely the external diameter of the lower end 35 of the strut 34 prior to the tightening of the pinch bolt 32. The close matching of diameters makes it difficult to locate the strut 34 in the opening 26 as the body is being lowered and an object of the present invention is to provide an improved suspension which will help to reduce that problem.

According to a first aspect of the invention there is provided a vehicle suspension comprising a wheel mounting member and an upwardly extending strut, the strut having a lower end connected to the mounting member and an upper end connected, in use, to a body or chassis of the vehicle, the connection between the wheel mounting member and the strut comprising a tapered surface on one of the wheel mounting member and strut which locates the other of the wheel mounting member and strut so as to position the strut and wheel mounting member correctly relative to each other and fixing means for holding the located strut and wheel mounting member together.

The use of a tapered surface aids location of the strut on to the wheel mounting thereby avoiding the problem of having to locate the cylindrical lower end of a strut in an opening of closely similar diameter.

Preferably, the lower end of the strut locates in an upwardly directed opening in the wheel mounting member, the tapered surface being formed around the upper end of the opening.

The tapered surface may be an external surface extending around the upper end of the opening which makes contact with a projection on the strut to position the strut within the opening. The projection itself may have a tapered internal surface which receives the external tapered surface as the lower end of the strut is located in the opening. With such an arrangement a clearance is defined between a wall of the opening and the lower end of the strut so that the lower end can easily be positioned in the opening. Preferably the projection is substantially annular so as to form a cover extending across the clearance to inhibit entry of foreign matter and moisture into the clearance. The projection may be formed as a sleeve mounted near the lower end of the strut and a stop may be provided on the strut to inhibit axial movement of the sleeve along the strut as the lower end is being fixed in position in the opening. Preferably, the sleeve has stiffening formations thereon.

Another problem with the prior strut fixing arrangement shown in Figs 1 and 2 involves the positioning and tightening of the pinch bolt 32. Once the somewhat difficult step of positioning the lower end 35 of the strut 34 in the opening 26 has been completed, the pinch bolt 32 is then tightened. However, the pinch bolt 32 is difficult to access in the position shown. Moreover, the provisions of the split 28 and the holes 31 in the lugs 30 require additional manufacturing operations thereby increasing the overall cost of the wheel mounting member 10. Such disadvantages can be substantially reduced in the present invention where the opening 26 can have an open lower end and the fixing means, preferably a screw threaded fastener arrangement, may extend axially of the strut. In one embodiment, the screw threaded fastener arrangement comprises a bolt fixed to the lower end of the strut and nut which is screwed on to the bolt after the lower end of the strut has been located on the wheel mounting member.

In that way, the bolt on the lower end of the strut passes through the opening during assembly and is readily accessible from the open lower end of the opening to receive the fixing nut. Alternatively, a nut can be fastened to the lower end of the strut ready to receive a bolt once the lower end of the strut has been positioned within the opening.

A clamping member for the lower end of the strut may locate in the open lower end of the opening. The clamping member may be formed with an aperture through which passes a part of the fixing means. Preferably, part of the clamping member extends across a surface surrounding the open lower end of the opening and the clamping member is urged against the said surface by the fixing means to secure the strut in the opening. The surface surrounding the lower end surface of the opening may be a tapered surface and the said part of the clamping member which is urged against the tapered surface may itself have a tapered surface.

The aforesaid tapered surfaces may be of frusto-conical form. Preferably, the angle of taper is such that interengaging tapered parts can easily be separated on releasing the fixing means.

The wheel mounting member may be steerable and antirotation means may be provided to prevent relative rotation between the strut and the wheel mounting member during such steering movement. The anti-rotation means may comprise a projection on one of the wheel mounting member and the strut and a mating recess on the other of the wheel mounting member and strut.

According to another aspect of the invention there is provided a vehicle having a suspension of the kind set out in the aforesaid first aspect of the invention or any of the consistory clauses relating thereto.

Vehicle suspensions in accordance with the invention will now be described by way of example with reference to the remaining accompanying drawings in which: Fig 3 is a cross section through part of a further wheel mounting member formed with an upwardly directed opening having an external tapered surface around its upper end and showing the lower end of a strut therein, Fig 4 is a view of part of the wheel mounting shown in Fig 3 having alternative clamping member arrangements shown to the left and right of a centreline respectively, Fig 5 is a cross section through part of a further wheel mounting member similar to that shown in Fig 3 having a tapered internal surface around a lower end of the opening for contact with a clamping member, Fig 6 is a further cross section through part of a wheel mounting member which receives a tapered lower end of a strut, and Fig 7 is a view similar to Fig 6 where the lower end of the strut carried a tapered sleeve.

In Figs 3 to 7, parts generally corresponding to parts shown in Figs 1 and 2 carry the same reference numerals.

Looking at Fig 3, the opening 26 is of cylindrical form and receives the lower end 35 of the strut 34 with substantial working clearance 52. The upper end of the boss 24 is formed with an external frusto-conical surface 80 having an angle of taper of around 45". The strut 34 carries a sleeve 82 having a projection in the form of a flared skirt 84 defining an internal frusto-conical surface 86. The surface 86, has an angle of taper corresponding to that of surface 80. The sleeve 82 is formed from sheet metal and has a plurality of circumferentially spaced stiffening swages 88. The strut 34 is formed with a peripheral swage 90 which acts as a stop restricting upward axial movement of the sleeve 82 on the strut 34 as viewed in Fig 3. A suitable interconnection (not shown) between the sleeve 82 and the strut 34 ensures that the sleeve 82 cannot rotate around the strut 34. If desired, such rotation can be prevented by welding the upper end of the sleeve 82 to the strut 34. The lower peripheral edge of the skirt 34 is formed with pairs of circumferentially spaced apart fingers 91 which overlie the boss 24. The fingers 91 define a space 92 therebetween for locating an anti-rotation dog 94 projecting from the boss 24. As shown in Fig 4, two such anti-rotation dogs 94 are arranged spaced apart by 900. However, it will be appreciated that a single anti-rotation dog 94 can be provided for location by any of the recesses 92. Also, the anti-rotation dogs 94 may be spaced by any other suitable angle, e.g. 1800.

The fingers 91 are shaped so that the space 92 is tapered. In that way, the fingers 91 and anti-rotation dogs 94 provide a useful location in a rotational sense for the lower end of the strut 34 as the strut enters the opening 26.

The bottom of the strut 34 has a housing 59 thereon for a captive screw-threaded nut 96. A clamping plate 62 is provided and has a cylindrical section 64 which locates within the opening 26, an outwardly directed annular flange 66 which abuts the bottom of boss 24 and an inwardly directed annular section 68 formed with a coaxial bore 70.

On assembling the vehicle body on to the suspension, the lower end 35 of the strut 34 is easily located in the opening 26 by virtue of the clearance 52 and is lowered into the opening until the frusto-conical surfaces 80, 86 contact each other as shown in Fig 4. The clamping plate 62 is then inserted into the opening 26 and a clamping bolt 98 is inserted through the bore 70 in the clamping plate 62 and screwed into the captive nut 96. Tightening of the bolt 98 is continued until the lower end 35 of the strut 34 is fully secured within the boss 24 with the boss itself being clamped between the skirt 84 of the sleeve 82 and the flange 66 of the clamping plate 62.

The skirt 84 of the sleeve 82 covers the upper end of the clearance 52 between the lower end 35 of the strut 34 and the boss 24. In that way, the skirt 84 prevents foreign matter and moisture entering the clearance 52.

Fig 4 shows alternative forms of clamping plate 62a, 62b drawn in part to the right and the left of a centre line C.

To the right of the centre line C, the clamping plate 62a is bent to form a frusto-conical flange 100 having an edge 102 which abuts a narrow frusto-conical chamfer 104 formed at the lower end of the opening 26.

To the left hand side of the centre line C, the alternative clamping plate 62b is bent to form a flange 106 having a peripheral margin which locates within a small counter bore 108 in the boss 24 at the lower end of the opening 26. A screw threaded fastener arrangement generally indicated at 110 can be used to hold the lower end 35 of the strut 34 within the opening 26. The clamping plates 62a, 62b shown in Fig 4 can replace the clamping plate shown in Fig 3 provided that the lower end of the boss 24 in each case is appropriately formed.

In Fig 5, the arrangement shown is somewhat similar to that shown in Fig 3 with the sleeve 82 suitably mounted on the strut 34. Parts corresponding to parts shown in Fig 3 carry the same reference numerals and are not described in detail.

The main difference between the arrangement shown in Fig 3 and that shown in Fig 5 lies in the shape of the clamping plate 62. In Fig 5, the clamping plate 62 is formed with a downwardly projecting frusto-conical flange 112 which is urged into contact with a frusto-conical internal surface 114 on the boss 24 at the lower end of the opening 26. A screw threaded fastener arrangement 116 is used to secure the lower end 35 of the strut 34 within the opening 26 with the boss 24 itself clamped between the skirt 84 of the sleeve 82 and the frusto-conical flange 112 of the clamping plate 62.

By ensuring that a clearance 52 is defined as shown in Figs 3 to 5 between the boss 24 defining the opening 26 and the lower end 35 of the strut 34, it is not necessary to provide a fine tolerance machined finish on the bore 26 as in Fig 1. Also, by placing the screw threaded fixing arrangement at the lower end of the opening 26, the need for a split 28 and projecting lugs 30 on the boss 24 is completely avoided which is advantageous from a manufacturing and packaging point of view.

The provision of frusto-conical surfaces 80, 86 in Figs 3 and 5 provide ideal self centering for the lower end 35 of the strut 34 within the bore 26. However, as the surfaces 80, 86 are not inclined at a shallow angle, special tools will not be required to "break" the taper fit where the strut 34 needs to be removed during servicing.

In that respect the angle of taper of the frusto-conical surfaces 80, 86 may be suitably selected to avoid friction taper locking which would require special tools to separate the two surfaces.

Looking at Fig 6 the lower end 35 of the strut 34 is of frusto-conical form and a screw threaded stud 120 projects downwardly from the bottom of the strut. The boss 24 is formed with an opening 26 of frusto-conical form which is of complementary shape to the frusto-conical lower end 35 of the strut 34. Once the lower end 35 of the strut 34 has been inserted into the opening 26, a clamping plate 62 in the form of a flat washer is placed in position on the stud 120 and a nut 122 is screwed on to the stud 120 to secure the strut 34 in position.

In Fig 7, the lower end 35 of the strut 34 is suitably held within a cylindrical bore 124 of a sleeve 126 formed with a frusto-conical outer surface 128. The sleeve 126 then locates in a complementary shaped frusto-conical opening 26 in the boss 24 in the same manner as that shown in Fig 6.

It will be appreciated that it is much easier to assemble a vehicle body on to a suspension in accordance with the invention than in the case described with respect to Figs 1 and 2. With a suspension in accordance with the invention, assembly of the body and suspension can be fully automated without the need for manual alignment of the lower end 35 of the strut 34 and the opening 26. Whilst reference is made to the lowering of the body on to the suspension, assembly can equally be effected by lifting the suspension into the body.

Claims

1. A vehicle suspension comprising a wheel mounting member and an upwardly extending strut, the strut having a lower end connected to the mounting member and an upper end connected, in use, to a body or chassis of the vehicle, the connection between the wheel mounting member and the strut comprising a tapered surface on one of the wheel mounting member and strut which locates the other of the wheel mounting member and strut so as to position the strut and wheel mounting member correctly relative to each other and fixing means for holding the located strut and wheel mounting member together.

2. A vehicle suspension according to Claim 1 in which the lower end of the strut locates with clearance in an upwardly directed opening in the wheel mounting member having the tapered surface formed around the upper end.

3. A vehicle suspension according to Claim 2 in which the tapered surface is an external surface extending around the upper end of the opening which makes contact with a projection on the strut to position the strut within the opening.

4. A vehicle suspension according to Claim 3 in which the projection has a tapered internal surface which receives and contacts the external tapered surface as the lower end of the strut is located in the opening.

5. A vehicle suspension according to Claim 4 in which the projection is substantially annular and forms a cover extending across the said clearance to inhibit entry of foreign matter and moisture into the clearance.

6. A vehicle suspension according to Claim 3, 4 or 5 in which the projection is formed as a sleeve mounted on the strut.

7. A vehicle suspension according to Claim 6 in which stop means is provided on the strut to inhibit axial movement of the sleeve along the strut as the strut is being fixed in position in the opening.

8. A vehicle suspension according to Claim 6 or 7 in which the sleeve has stiffening formations thereon.

9. A vehicle suspension according to any of Claims 2 to 8 in which the lower end of the opening is open and a clamping member for the lower end of the strut locates in the lower end.

10. A vehicle suspension according to Claim 9 in which the clamping member is formed with an aperture through which passes a part of the fixing means.

11. A vehicle suspension according to Claim 9 or 10 in which part of the clamping member extends across a surface surrounding the lower end of the opening and the clamping member is urged against the said surface by the fixing means to secure the strut in the opening.

12. A vehicle suspension according to Claim 11 in which the surface surrounding the lower end surface of the opening is a tapered surface.

13. A vehicle suspension according to Claim 12 in which the said part of the clamping member which is urged against the tapered surface has itself a tapered surface.

14. A vehicle suspension according to Claim 1 in which the lower end of the strut is formed with a tapered surface which fits into a recess in the wheel mounting member having a complementary shaped tapered surface.

15. A vehicle suspension according to Claim 1 in which the lower end of the strut carries a member having a tapered surface which fits into a recess in the wheel mounting member having a complementary shaped tapered surface.

16. A vehicle suspension according to any preceding Claim in which the or each tapered surface is of frusto conical form.

17. A vehicle suspension according to any preceding Claim in which the fixing means is a screw- threaded fastener arrangement which extends axially of the strut.

18. A vehicle suspension according to Claim 17 in which the screw-threaded fastener arrangement comprises a first screw threaded element fixed to the lower end of the strut and a second screw-threaded element which is screwed on to the first screw-threaded element after the lower end of the strut has been located on the wheel mounting member.

19. A vehicle suspension according to any preceding Claim in which anti-rotation means is provided to prevent relative rotation between the strut and the wheel mounting member.

20. A vehicle suspension according to Claim 19 in which the anti-rotation means comprises an anti-rotation projection on one of the wheel mounting member and strut and a mating recess on the other of the wheel mounting member and strut.

21. A vehicle suspension constructed and arranged substantially as described herein with reference to Fig 3, 4, 5, 6 or 7 of the accompanying drawings.

22. A vehicle having therein a vehicle suspension according to any preceding claim.