GB2059366A

GB2059366A - Vehicle suspensions

Info

Publication number: GB2059366A
Application number: GB8030049A
Authority: GB
Original assignee: Rover Co Ltd
Current assignee: Rover Co Ltd
Priority date: 1979-09-15
Filing date: 1980-09-15
Publication date: 1981-04-23
Also published as: GB2059366B

Abstract

A vehicle road wheel suspension is arranged so that the hub carrier 12 can pivot about an axis B-B disposed substantially vertically below and parallel to the hub's rotational axis. When applied to a steerable wheel, the hub carrier pivot axis is offset from the steering axis to provide the correct amount of castor. The arrangement affords high degrees of compliance to reduce vibration and noise transmitted to the vehicle structure. <IMAGE>

Description

SPECIFICATION Improvements relating to vehicle suspensions This invention relates to vehicle road wheel suspensions.

In such suspensions a reduction in the transmission of noise and vibration from the hub to the vehicle body structure has hitherto been sought by using compliant bushes to mount the suspension arms locating the hub. The use of such bushes can lead however, to imprecise location of the hub and so-called "rear-end steer" etc.

According to the invention there is provided a vehicle road wheel suspension, including a hub carrier located by one or more suspension links, wherein the arrangement is such that the hub carrier is capable of pivotal movement about an axis substantially parallel to the hub axis and located substantially vertically below the centre of the hub.

Embodiments of the invention will now be described by way of example and with reference to the accmpanying drawings, in which: Figure 1 is a front view of a motor vehicle rear suspension in accordance with the invention; Figure 2 is a plan view of the suspension of Figure 1, with parts omitted for clarity; Figure 3 is a front view of a motor vehicle front suspension in accordance with the invention; Figure 4 is a plan view of the suspension of Figure 3; Figure 5 is a transverse cross section of a third embodiment of a suspension in accordance with the invention; and Figure 6 is a side view of the suspension of Figure 5.

As shown in Figures 1 and 2 a left hand rear road wheel 11 of a vehicle is rotatably carried by a hub carrier 12 and is driven by way of a drive shaft 13 having a pair of universai joints 14 (omitted from Figure 2 for clarity). Drive shaft 13 functions also as an upper linkforthe suspension, providing lateral location of the upper end of hub carrier 12.

The lower end of hub carrier 12 is located both laterally and longitudinally of the vehicle by suspension links 15 and 16. Links 15 and 16 are attached to the vehicle so as to pivot about a longitudinal axis A (Figure 2), while at its outer end link 15 is attached to the hub carrier 12 for pivotal movement about an axis substantially parallel to axis A.

Link 15 comprises a pair of coaxial tubes 18, tube 18 being fitted inside tube 17 and connected thereto in such manner as to permit relative pivotal movement between the tubes but not relative axial movement. The tubes are connected by bonded rubber in like manner two known vibration-damping prop-shafts, whereby relative pivotal movement is elastically resisted. Such relative pivotal movement enables the hub carrier 12 to execute, with tube 18, pivotal movement about an axis B-B transverse to the vehicle and located substantially vertically below the centre of the hub in a static condition.This movement is limited by a pin 19 moving- in a slot defined by an extension 20 of a collar 21 fixed on tube 17, the collar serving also as a point of connection for link 16 and to provide a mounting point 22 for a spring and damper unit (not shown) for the suspension.

In the embodiment shown in Figures 3 and 4, a steerable lefthand front road wheel 31 of a vehicle is rotatably carried by a hub carrier 32. Hub carrier 32 is located at its lower end longitudinally and transversely of the vehicle, by an A-shaped arm 33, attached to the vehicle structure 34 for pivotal movement about a longitudinal axis of the vehicle, and connected to the hub carrier by a ball-joint 35.

Steering of the hub carrier and hence the wheel is controlled by a track rod 36 connected by a ball joint 37 to an arm 38 integral with the hub carrier 32.

The upper end of hub carrier 32 is located by a linkage 39 which is arranged to substantially predetermine the lateral position of the hub carrier, whilst permitting some free movement of the upper end longitudinally of the vehicle. Linkage 39 comprises an H-shaped arm 30 attached to the vehicle structure for pivotal movement about a longitudinal axis of the vehicle, a pair of links 41 pivotally connected at one end to the H-shaped arm 40 for movement in a plane parallel to the arm 40, and pivotally connected at their other ends to a link 42 which can move on links 41 in the plane of the H-shaped arm. The link 42 is connected at its midpoint to the upper end of the hub carrier by way of a ball joint 43. Movement of link 42 relative to the H-shaped arm is limited by a pair of stops 44 on the arm which engage links 41.

As in the previous embodiment, the arrangement permits pivotal movement of the hub carrier about an axis substantially transverse to the vehicle and located substantially vertically below the hub centre, namely through the lower ball joint 35. In the second embodiment, the horizontal force transmitted by the ball joint 43 to the linkage tends to centre the link 42 at its static position.

Figures 5 and 6 show a suspension arrangement for a non-driven steerable front wheel of a vehicle. A hub carrier comprising a brake and wheel mounting disc 50 has a stub axle 51 carried by taper roller bearings 52 in a housing 53. Housing 53 is itself pivotally mounted about an axis X-X parallel to and vertically below stub axle 51 by means of roller bearings 55 which run on a shaft 56 rigidly mounted in a figure '8'-shaped yoke 57.

Yoke 57 includes an integral arm 58 for connection to the vehicle's steering linkage, a socket for a lower ball joint 59 the stub 60 of which is connected to a lower wishbone (not shown), and an upper mounting 61 for attachment to the lower end of a Macpherson strut (not shown) or alternatively to the outer end of an upper wishbone. Thus yoke 57 can be pivoted about a substantially vertical axis to provide a steering function.

At the top and rear of yoke 57 are carried elastomeric buffers 62 and 63, which engage buffer pads 64 and 65 respectively, integral with housing 53, and which serve to limit rotation of the housing 53 relative to the yoke 57 about axis X-X.

It will be seen that the arrangement of Figures 5 and 6 involves locating the stub axle in side by side relation with a shaft in single shear about which the hub carrier can pivot, and as such provides a very compact configuration in which the housing is pivoted as close as possible to the wheel centreline.

To compensate for the loss of castor angle that occurs by virtue of the ability of the hub axis to swing forward of the yoke pivot axis (line Y-Y) if the hub fulcrum X-X intersects the yoke pivot axis, X-X is offset a distance a behind the yoke pivot axis to ensure that when at its mean position the hub axis intersects the steering pivot axis, so that the amount of casTOr is determined entirely by the inclination of the yoke pivot axis to the vertical.

Housing 53 also carries brake parts (not shown) for engaging a brake disc two be irrotatably mounted on mounting disc 51. Thus under braking a torque is imposed on housing 53, which acts in a clockwise sense in Figure 2, and accordingly it is buffer 62 which prevents excessive rotation of the hub carrier housing during braking. It will be noticed that buffer 62 is located at a greater distance from the axis X-X than buffer 63, because the braking torque is likely to be greater than any torque applied to the hub carrier in the opposite sense. The arrangement shown is for a relatively heavy passenger car, and the elastomeric buffers are rated at 1000 pounds/inch; a lighter car could employ softer buffers.The maximum working deflection of the stub axle is designed to be 1/2 inch, typical deflection being of order 3/8 inch; it is intended that at least 1/8 inch travel be provided to justify employment of the arrangement illustrated.

In all the embodiments the vertical load on the wheel tends to restore the hub carrier to its static position. Therefore in the case of the driven wheel, deflection caused by tractive effort can be reduced by the additional vertical loading on the wheel caused by weight transfer under acceleration.

By permitting the hub centre thus to move independently of the vehicle structure, high degrees of compliance are afforded to reduce vibration and noise transmitted to the vehicle structure, but with out such great penalties of induced steer as result from the use only of compliant bushes. The arrangements shown are capable of attenuating relatively low frequency vibrations as compared to conventional bushes, while the mass of the hub, locating linkage and brake parts can be used as a noise attenuator.

Claims

1. Avehicle road wheel suspension, including a hub carrier located by one or more suspension links, wherein the arrangement is such that the hub carrier is capable of pivotal movement about an axis substantially parallel to the hub axis and located substantially vertically below the centre of the hub, at least when the hub axis is substantially transverse to the vehicle.

2. A suspension as claimedin claim 1, wherein said hub axis is capable of at least 1/8 inch movement longitudinally of the vehicle.

3. A suspension as claimed in claim 1 or 2, wherein said hub axis is capable of 3/8 inch movement longitudinally of the vehicle.

A A suspension as claimed in claim 1, 2 or 3, wherein said wheel is steerable about a steering axis, said hub carrier pivotal axis being offset from the steering axis to provide castor.

5. A suspension as claimed in any one of claims 1 to 4, wherein said hub carrier is pivoted on a shaft carried by said suspension link(s) in single shear.

6. A suspension as claimed in claim 5, wherein said hub carrier is journalled on said shaft by bearings which axially overlap the bearings permitting normal rotation of the hub, to reduce the axial dimension of the assembly.

7. A suspension as claimed in claim 5 or 6, wherein said shaft is carried by a member pivotable about a steering axis and including a steering arm for connection to a steering mechanism.

8. A suspension as claimed in any preceding claim, wherein the upper part of the hub carrier is located by a pair of arms swingable in a substantially horizontal plane to permit said upper part to move longitudinally of the vehicle.

9. A suspension as claimed in claim 8, wherein said arms are so arranged that horizontal loadings transmitted between them and the hub carrier tend to centre the hub carrier in its static position.

10. A suspension as claimed in any one of claims 1 to 4, wherein said hub carrier is located by a lower suspension arm comprising a pair of tubes coaxial with one another and with said hub carrier pivot axis, said tube being connected to the hub carrier and to the vehicle frame respectively, one of said tubes being carried partly within the other and constrained against relative axial movement, relative rotation of the tubes being controlled by elastomeric means thereby to control longitudinal movement of the hub relative to the vehicle.

11. A vehicle road wheel suspension substantially as hereinbefore described with reference to Figures 1 and 2, orto Figures 3 and 4, orto Figures 5 and 6 of the accompanying drawings.