IES960113A2 - Vehicle suspension - Google Patents

Abstract

A vehicle suspension apparatus (40) for connecting a wheel to a vehicle chassis (41) has two mechanical connections (43,46,47) with the vehicle chassis (41) and a pressure fluid operable spring (50) <Fig.4>.

Description

VEHICLE SUSPENSION present in zention relates to a vehicle suspension.

Even on reasonably good roads the body of a vehicle is subjected to three different types of motion, i.e. bounce, roll and pitch. The function of a vehicle suspension system is to counteract the effects of this motion so as to provide a safe and comfortable ride.

One known vehicle suspension unit, as illustrated in rig.I, comprises a mechanical arrangement 10 in which semielliptical spring leaves 11 are provided at each end of the vehicle axle 12 for attaching the axle 12 to the vehicle chassis 13. The ends of the semi-elliptical spring leaves 11 are fixed to the chassis 13 by a pivotal connection 14 at one end and by a second pivot 15 to a swinging shackle 18 at the other end.

An alternative form of suspension unit is a pneumatic suspension, A pneumatic suspension 20 is shown in Fig.2. Here the suspension unit comprises a trailing arm which extends rearwardly from a pivotal connection 22 with the chassis and extends either above or below the axle 24 to provide a platform for a pneumatic air spring 25. The pneumatic spring 25 is located between the non-fixed end of the trailing arm 21 and the vehicle chassis 23. Thus the only restricted fixture is at the pivotal connection. One such suspension arrangement is provided at each side of the vehicle OPEN TO PUBL IC INSPECTION UN' . B SECTION 28 AND RULE 23 JNL No. ./7.1.3.....Of 960111 chassis, each providing a rigid connection 26 between the trailing arm 21 and the vehicle axle some distance from the pivotal connection.

The trailing arms 21 may comprise a spring leaf or a fabricated metal structure.

Side location for the axle is provided by the .rigid clamping of the trailing arms to the axle maintaining a 90° angle between them. A panhard rod may alternatively be used.

For any upwards or downwards travel of the axle 24 shown 10 in Fig.2 to take place a greater movement of the air spring 25 is required. For normal axle travel this is accommodated by commercially available air springs. However, recent market conditions have demanded much greater axle travel than was previously thought acceptable. This greater axle travel 1 5 cannot be achieved with an acceptable ride by the suspension illustrated in Fig.2.

A further known suspension 30 is illustrated in Fig.3. Here an air spring 31 is located in front of the axle 32; that is closer to the pivotal connection 33. However, because of 20 the proximity of the load carrying points 31,33 this suspension provides poor ride comfort and additional stresses are transmitted to the chassis.

The present invention seeks to provide a suspension that 9601 fj facilitates satisfactory ride comfort in conditions of increased axle travel.

According to the present invention there is provided a vehicle suspension apparatus for connecting a wheel to a vehicle chassis, said suspension apparatus having at least two mechanical connections with the vehicle chassis and further comprising a pressure fluid operable spring.

The suspension apparatus described above is conventionally located on one side of a vehicle chassis, a similar apparatus being provided on the other side of the vehicle chassis. The suspension of the apparatus provides a sufficient number of attachment points with the chassis to spread the load along the chassis.

The pressure fluid operable spring may be hydraulic, but is ideally pneumatic.

The vehicle suspension apparatus ideally comprises a trailing arm that is pivotally connected to the chassis and extends rearwardly to the axle. A rigid connection is ideally provided between the trailing arm and the axle.

A second link is preferably provided between the trailing arm and a pivotal connection with the chassis. A pivotal connection is preferably provided between the trailing arm and the second link- The pivotal connection with the trailing arm 9601 1 J* is ideally in front of the axle. The pivotal connection with the chassis preferably involves a swinging shackle.

The pressure fluid operable spring is ideally located on the second link at a position above the lowermost position of the second link. The positioning of the pressure fluid operable spring is such that the spring is subjected to less extension during axle travel than would be required for conventional systems.

The invention will now be described further, by way of example, with reference to the accompanying diagrammatic drawings, wherein:Fig.l is a side elevation showing a first prior art suspension system; Fig. 2 is a side elevation of a second prior art suspension system; Fig. 3 is a side elevation of a third prior art suspension system; and Fig.4 is a side elevation of a suspension in accordance with the present invention.

The prior art of Figs. 1 to 3 have been discussed in detail in the introductory paragraphs hereof and will not be 011Ja discussed further here.

Referring to Fig. 4 a suspension 40 in accordance with the present invention is located below a vehicle chassis 41. A flange 42 depends from the chassis 41. one end of a trailing arm 43 is connected to the flange 42 by a pivot 44. The trailing arm 43 extends rearwardly from the pivot 44 to the vehicle axle 45 which is rigidly connected to the end of the trailing arm 43 which is remote from the pivotal connection 44. The trailing arm 43 may comprise a spring leaf or a fabrication. The trailing arm 43 is conventionally made from metal, such as steel.

A swinging shackle 46 depends from the chassis 41 from a position located rearwardly of the vehicle axle 45. One end of a second link 47 is pivotally connected to the base of the trailing arm 43 or a flange depending therefrom at a position forward of the axle 45. The second link 47 extends below the axle 45 and extends to the free end of the swinging shackle 46. A pivotal connection 48 is provided between the second link 47 and the free end of the swinging shackle 46. It is noted that the swinging shackle 46 is connected to the chassis by a pivot 49. An air spring 50 is located on top of the second link 47 between the axle 45 and the swinging shackle 46. The air spring 46 supports the chassis 41.

It is noted that one suspension unit as described above is provided at each side of the vehicle chassis. Ο 11J In this suspension arrangement the stroke of the air spring 50 is less than the movement of the axle 45, thus facilitating greater ride comfort at extreme axle travel conditions. In addition the axle 45 is attached to the 5 chassis at four points (2 points per suspension unit) as with a mechanical suspension. The air spring 50 is located to the rear of the axle 45 away from the pivotal connection 42 with the chassis thus maintaining load spread along the chassis.

It is to be understood that the above described 10 embodiment is by way of illustration only. Many modifications and variations are possible.

Claims (5)

1. A vehicle suspension apparatus for connecting a wheel to a vehicle chassis, said suspension apparatus having at least two mechanical connections with the vehicle chassis and 5 further comprising a pressure fluid operable spring.

2. A vehicle suspension apparatus as claimed in claim 1, wherein the trailing arm is pivotally connected to the chassis and extends rearwardly to an axle for the wheel.

3. A vehicle suspension apparatus as claimed in claim 1 or 10 claim 2, wherein a second link is provided between the trailing arm and a pivotal connection with the chassis.

4. A vehicle suspension apparatus as claimed in any preceding claim, wherein a pivotal connection is provided between the trailing arm and the second link. 15

5. A vehicle suspension apparatus as claimed in claim 4, wherein the said pivotal connection between the trailing arm and second link is located in front of an axle for the wheel.