GB2314306A

GB2314306A - Motor vehicle suspension stabiliser assembly

Info

Publication number: GB2314306A
Application number: GB9612900A
Authority: GB
Inventors: Clive William Rose
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-06-20
Filing date: 1996-06-20
Publication date: 1997-12-24
Anticipated expiration: 2016-06-20
Also published as: GB2314306B; GB9612900D0

Abstract

An assembly 1 comprises a pair of rocker arms 2, 4 coupled to the front wheel suspensions by links 3 and 5 and being mutually coupled by spring and damper assemblies 7,8 and 11, 12. The rocker arms are also coupled by a fluid cylinder 19 which is fluid-linked to the cylinder 58 of a similar assembly 29 of the rear suspension. A third such assembly 28 may be interposed between the cylinders 19 and 58, with fluid cylinders 41 and 42 coupled between the respective rocker arms 31, 32 and chassis.

Description

VEHICLE SUSPENSION TECHNICAL FIELD OF THE INVENTION This invention relates to vehicle suspension for motor vehicles, and in particular, but not exclusively, competition vehicles.

BACKGROUND Competition vehicles may demand a suspension system that is competent in maintaining the vehicle in the most stable manner possible throughout an extreme range of conditions. Many different configurations of suspension system are known, from a very basic independent spring and damper arrangement provided at each wheel of the vehicle to the more complex fluid or rod links from the front to rear wheels of the vehicle, and in some instances, from side to side.

It is also well known that suspension movement on one wheel of a vehicle can be transmitted to an opposing wheel by means of an anti-roll bar with the object of reducing vehicle body roll during cornering.

Some suspension systems comprise a partially floating centrally pivoted inter linked front axle, sometimes known as a monoshock, which raises one wheel when the other is raised, but this requires a floating arrangement to reduce the immediate effect of the reaction.

To provide an increase in spring rate when the suspension is under a high degree of load some suspension systems employ a second spring within a first spring, or alternatively have a spring manufactured from tapered rod thus providing a progressive effect.

In most suspension systems where a reaction at one wheel is transmitted to another wheel there is a degree of lost motion and this factor, coupled with spring rate and travel constraints, can lead to the handling of the vehicle being compromised to the detriment of maximum performance.

GB 2 231 539-A, GB 1 300 028, GB 1 228 842, GB 965 667, GB 669 545, and US 5 364 114 disclose a motor vehicle provided with an assembly which comprises a pair of rocker arms mounted for pivotal movement about generally parallel axes and which are coupled to respective wheel suspensions on opposite sides of the vehicle such that the rocker arms are displaced about the respective axes with substantially vertical movement of the respective suspensions, said rocker arms being mutually coupled by spring means.

The present invention seeks to provide a suspension system which is patentably different from any known form of suspension system.

SUMMARY OF THE INVENTION The present invention proposes a motor vehicle provided with an assembly which comprises a pair of rocker arms mounted for pivotal movement about generally parallel axes and which are coupled to respective wheel mounts on opposite sides of the vehicle such that the rocker arms are displaced about the respective axes with substantially vertical movement of the respective wheels, said rocker arms being mutually coupled by first spring means which couples the rocker arms on one side of said pivot axes and second spring means which couples the rocker arms on opposite sides of their respective pivot axes.

Preferably, the rocker arms are mutually coupled by damper means. More particularly, the first and second spring means are preferably associated with respective first and second damper means.

The rocker arms are preferably substantially coplanar.

The second spring means preferably has substantially no pre-compression when the vehicle is under static conditions.

The spring rate of the first spring means is preferably higher than that of the second spring means.

The said pivot axes are preferably disposed in an upright position.

In certain applications of the assembly, the rocker arms may be coupled by a fluid displacement device. The said fluid displacement device is preferably coupled to the rocker arms on the opposite side of the pivot axes to the first spring means.

A first such assembly may be coupled to the front wheels of the vehicle and a second such assembly coupled to the rear wheels. The fluid displacement devices of the first and second assemblies are preferably interconnected by fluid-conducting means.

The fluid conducting means preferably comprises a third such assembly of which the rocker arms are coupled to fixed points by respective fluid displacement devices which are coupled to the respective fluid displacement devices of the first and second assemblies. The fluid displacement devices of the third assembly are preferably connected to the rocker arms on the same side of the respective pivot axes as the first spring means.

BRIEF DESCRIPTION OF THE DRAWINGS The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: Figure 1 is a general plan view of a suspension assembly for either the front or rear of a motor vehicle, in accordance with the invention, Figure 2 is a general plan view of such front and rear suspension assemblies, and Figure 3 is a general plan view of three such suspension assemblies; one for the front of the vehicle, one for the rear of the vehicle and the third positioned somewhere between the front and rear assemblies.

DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 shows a suspension assembly 1, e.g. for the front of a vehicle, comprising rocker arm 2 which may be attached by push rod 3 at pivot 3a to the right hand wheel mount (not shown), and a rocker arm 4 attached by push rod 5 at pivot Sa to the left hand wheel mount (also not shown). Rocker arms 2 and 4 are centrally pivoted at 6 on the chassis of the vehicle (not shown) to pivot about upright, substantially vertical and mutual, parallel axes.

A combined parallel connected spring 7 and damper unit 8 is located approximately at right angles to and between the two rocker arms 2 and 4, to the same side of the main pivots 6, and is pivotally connected to rocker arm 2 at 9 and rocker arm 4 at 10. There is also a further such spring 11 and damper unit 12 set diagonally between rocker arms 2 and 4 and pivotally connected to rocker arm 2 at 13 and 4 at 14. The pivotal connections 13 and 14 thus lie on opposite sides of the main pivots 6. The ends of spring 11 may be secured with the opposite ends 15 and 16 of damper unit 12.

First example: In use, under braking conditions when the vehicle is travelling in a straight line, both push rods move towards each another compressing spring 7 thus bringing pivot points 9 and 10 closer together. Combined spring 11 and damper unit 12 may neither compresses or extend under this condition.

Further example: Under conditions where the vehicle is taking a right hand corner, and assuming the spring rate of spring 11 is greater than spring 7 and spring 11 has no pre-load applied on installation, push rod 5 may act to compress springs 7 and 11 with the result rocker arm 2 should remain reasonably static subject to other external forces such as a bump in the road, causing the right road wheel to rise.

Further example: Under left hand cornering spring 7 may be caused to compress and spring 11 may be caused to lengthen. Thus, the force provided by springs 7 and 11 on rocker arm 4 remains the same as the forces applied to rocker arm 2 in right cornering, due to the spring 11 being secured to the opposite ends of the damper unit 12.

Thus, as long as spring 11 is of greater spring rate than spring 7 then either under left or right hand cornering the opposing side of the front of the vehicle closer to the inner radius of the corner may be caused to lower, thereby generally lowering the centre of gravity.

It should also be noted that under straight line braking only spring 7 is operative, but under the conditions of left or right cornering described above, both springs 7 and 11 may support the body weight of the vehicle.

Figure 2 shows a plan view of two suspension assembly units. Assembly 1 for the front of the vehicle and assembly 17 for the rear. The two assemblies 1 and 17 may be constructed and function as described above in relation to Figure 1, save for the following: Assembly 1 may include a gas or liquid displacement cylinder 19 mounted between rocker arms 2 and 4 at pivot points 18, on the opposite side of the main pivots 6 to the first spring 7. Cylinder 19 may be interconnected to a similar displacement cylinder 20 in assembly 17 by means of fluid pipe 21.

In use, under uniform straight-line acceleration, ordinarily a vehicle may lower at the rear and the front may rise. However, by adopting the arrangement of Fig. 2 the push rods 22 connected to the respective rear wheels may tend to force the rear rocker arms 23 and 23a together at pivot points 24, due to the positioning of the main pivot 6b and the push rod pivot 22b. This in turn causes the combined first spring and damper unit 25 to lengthen, the spring 26 being held fast with the ends 25a of the respective damper 25b. Cylinder 20 thus shortens, thereby displacing fluid through pipe 21 and into cylinder 19 which in turn increases in length, thus causing spring 7 and damper unit 8 to shorten and push rods 3 and 5 to bring the front of the vehicle down.

It will be noted that under uniform acceleration or braking in this configuration the overall vehicle spring rate may be doubled due to springs 7 and 26 becoming operative together.

Further example: Under right hand cornering employing this configuration of assemblies 1 and 17, and assuming that the spring rates of diagonal springs 11 and 27 are set reasonably higher than springs 7 and 26, then cylinder 19 may be caused to increase in length and cylinder 20 may be caused to decrease in length causing the centre of gravity of the vehicle to be lowered generally.

Further example: Under acceleration and cornering the right rear rocker arm 23a may cause the diagonal spring and damper units 25 and 27b to lengthen, spring 27 being secured with end plates 27a of damper 27b. The right hand rear side of the vehicle may thus be caused to lower and cylinder 20 become shortened.

Fluid displacement causes cylinder 19 to lengthen, thus causing spring 7 to become compressed and the front of the vehicle to lower as well.

Figure 3 shows a plan view of three of the suspension assemblies of Fig. 1.

Assembly 1 is mounted at the front of the vehicle. Assembly 28 can be mounted anywhere on the vehicle since it is not directly linked by push rods to any of the road wheels of the vehicle. Assembly 29 is associated with the rear wheels of the vehicle.

Assembly 28 comprises rocker arms 31 and 32 which are pivotally attached at 33 to the vehicle chassis (not shown) for movement about upright pivot axes.

A combined parallel-connected spring 35 and damper 36 are pivotally attached at points 34 to rocker arms 31 and 32 to one side of the main pivot axes 33 approximately at right angles to rocker arms 31 and 32. The ends of spring 35 may be fast with the damper 36 on seats 36a. A further combined spring 37 and damper 38 is pivotally attached at points 39 and 40 diagonally to rocker arms 31 and 32. The ends of spring 37 are again held with damper 38 on seats 37b. Fluid displacement cylinders 41 and 42 are pivotally attached to rocker arms 31 and 32 at points 43, and to the vehicle chassis at points 44.

Assembly 29 comprises rocker arms 45 and 46 which are pivotally attached to the vehicle chassis at points 47. Push rods 48 and 49 from the vehicle road wheels are pivotally attached to rocker arms 45 and 46 at points 50. A combined spring 51 and damper unit 52 is set at approximately right angles to the rocker arms 45 and 46 and pivotally attached to rocker arms 45 and 46 at points 53. A diagonal spring 54 and damper 55 are pivotally attached to rocker arms 45 and 46 at points 56, the ends of spring 54 being captivated to damper 55 on seats 57. A displacement cylinder 58 extends between the opposite ends of rocker arms 45 and 46 from the spring 51, being pivotally attached at points 59.

Displacement cylinders 19 and 41 of assemblies 1 and 28 are interconnected by pipe 60, and cylinders 42 and 58 of assemblies 28 and 29 are interconnected by pipe 61.

In use, under uniform straight line braking conditions, push rods 3 and 5 may cause rocker arms 2 and 4 of assembly 1 to compress spring 7, whereupon cylinder 19 will lengthen thus drawing fluid out of cylinder 41 through pipe 60.

Rocker arm 31 may then pivot around 33 and cause springs 35 and 37 of assembly 28 to lengthen. But as springs 35 and 37 are firmly captivated on seats at 36a and 37b on dampers 36 and 37 the combined effect of'springs 7 of assembly 1 and springs 35 and 38 of assembly 28 may provide three times the normal suspension support under the said braking condition, thus reducing or possibly even eliminating the lowering of the front of the vehicle.

Equally, under acceleration when the rear of the vehicle may drop the effect of the support from the three springs 51 of assembly 29 and 35 and 37 of assembly 28 come into combined effect. However, in these circumstances spring 35 may be lengthened and spring 37 may be compressed.

It will be appreciated that in the setting up of the various spring pre-load settings when the assemblies 1, 28 and 29 are first installed on the vehicle, springs 11, 35, 37 and 54 may be in their relaxed state.

Further example: under conditions of right hand cornering with this configuration of the suspension assemblies 1, 28 and 29, and assuming the spring rate of spring 11 is greater than for spring 7 of assembly 1, then cylinder 19 may be caused to lengthen thus shortening cylinder 41, which may again have the effect of extending springs 35 and 37 of assembly 28. The combined effect of this may be the support of four springs under the said cornering conditions.

It may also be desirable for the various pivot points depicted herein to be varied in location according to performance. In some instances it may also be desirable to eliminate one or more suspension and or damper units within one or more of the assemblies 1, 28 and 29, again according to performance requirements.

The present invention thus provides a means whereby the body of a vehicle will be maintained at the most advantageous plane under cornering, braking, acceleration or any variations of same, even under uneven terrain conditions.

Whilst the above description lays emphasis on those areas which, in combination, are believed to be new, protection is claimed for any inventive combination of the features disclosed herein.

Claims

1. A motor vehicle provided with an assembly which comprises a pair of rocker arms mounted for pivotal movement about generally parallel axes and which are coupled to respective wheel mounts on opposite sides of the vehicle such that the rocker arms are displaced about the respective axes with substantially vertical movement of the respective wheels, said rocker arms being mutually coupled by first spring means which couples the rocker arms on one side of said pivot axes and second spring means which couples the rocker arms on opposite sides of their respective pivot axes.

2. A motor vehicle according to Claim 1, in which the rocker arms are mutually coupled by damper means.

3. A motor vehicle according to Claim 2, in which the first and second spring means are associated with respective first and second damper means.

4. A motor vehicle according to any preceding Claim, in which the rocker arms are substantially coplanar.

5. A motor vehicle according to any preceding claim, in which the second spring means has substantially no pre-compression when the vehicle is under static conditions.

6. A motor vehicle according to any preceding claim, in which the spring rate of the first spring means is higher than that of the second spring means.

7. A motor vehicle according to any preceding claim, in which the said pivot axes are disposed in an upright position.

8. A motor vehicle according to any preceding claim, in which the rocker arms are coupled by a fluid displacement device.

9. A motor vehicle according to Claim 8, in which said fluid displacement device is coupled to the rocker arms on the opposite side of the pivot axes to the first spring means.

10. A motor vehicle according to any preceding claim, in which a first such assembly is coupled to the front wheels of the vehicle and a second such assembly is coupled to the rear wheels.

11. A motor vehicle according to Claim 10 as appended to Claim 8 or 9, in which the fluid displacement devices of the first and second assemblies are interconnected by fluid-conducting means.

12. A motor vehicle according to Claim 11, in which the fluid conducting means comprises a third such assembly of which the rocker arms are coupled to fixed points by respective fluid displacement devices which are coupled to the respective fluid displacement devices of the first and second assemblies.

13. A motor vehicle according to Claim 12, in which the fluid displacement devices of the third assembly are connected to the rocker arms on the same side of the respective pivot axes as the first spring means.

14. A motor vehicle provided with one or more assemblies substantially as described with reference to Fig.s 1, 2 or 3 of the drawings.