GB1559681A

GB1559681A - Levelling valve assemblies

Info

Publication number: GB1559681A
Application number: GB4860375A
Authority: GB
Original assignee: Girling Ltd
Current assignee: Girling Ltd
Priority date: 1975-11-26
Filing date: 1975-11-26
Publication date: 1980-01-23

Description

(54) IMPROVEMENTS IN OR RELATING TO LEVELLING VALVE ASSEMBLIES (71) We, GIRLING LIMITED, a British Company, of Kings Road, Tyseley, Birmingham 11, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment:- This invention relates to levelling valve assemblies for vehicles.

Leveling valve assemblies are usually mounted on the sprung part of the vehicle and are operative in response to relative movement between the sprung and the unsprung part of the vehicle to introduce pressure fluid into a suspension strut or spring from a pressure source, such as an accumulator, or release pressure from the strut.

Pressure in the strut is increased when the vehicle is loaded and decreased when the vehicle is unloaded.

Previously proposed valve assemblies comprise an inlet valve controlling communication between the accumulator and the strut and an exhaust valve controlling communication between the strut and a reservoir. The valves are usually damped to avoid operation when changes in vehicle loading are transient, for example when riding along an uneven road surface.

In accordance with the present invention, there is provided a levelling valve assembly for a vehicle suspension system, comprising a normally closed inlet valve for controlling communication between an inlet for pressure fluid and a port for connection to the suspension system, a normally closed exhaust valve for controlling communication between said port and an exhaust opening, each valve having a closure member movable to operate the valve, two damping assemblies one associated with each valve, wherein each damping assembly is located between its associated valve closure member and operating means, which normally prevents movement of the damping assemblies said operating means being operable in use in response to vehicle loading to permit movement of one of the damping assemblies and its associated closure member in a direction to open the associated valve, movement of the damping assembly in that direction being damped.

Preferably, each damping assembly comprises a damper piston which may work in a chamber on the outlet side of its associated valve.

The valve assembly is preferably so constructed that the inlet valve and its associated damping assembly are of identical construction to the exhaust valve and its damping assembly. Thus manufacturing costs are minimised and the stock of replacement parts to be held is reduced.

A levelling valve assembly for a vehicle suspension system will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevational view of the valve assembly with part of the housing shown cut away; Figure 2 is a section taken along line A-A of Figure 1; Figure 3 is a section taken along line B-B of Figure 2, and Figure 4 is a scrap section taken along line C-C of Figure 1.

The valve assembly is shown with its parts adopting a neutral position and comprises the housing 1 having parallel bores 2 which receive respectively identical valve and damper arrangements. In the following description the same reference numerals are used for corresponding parts of the valve and damper arrangements but the numerals of the right-hand have been given the suffix A.

Since the arrangements are identical only the left-hand arrangement is described in full.

That valve and damper arrangement comprises a valve member 3 held in place by an end plug 4 and carrying spaced seals 5. A passageway 6 is formed between the seals 5 and communicates through an opening 7 with a chamber 8 within which a damper piston 9 slides. A valve 10 comprises a valve closure member 11 which co-operates with a valve seat formed on the member 3 and controls the passage of fluid through the opening 7. The upper part of left-hand chamber 8 (as seen in Figure 2) is connected to the passageway 6A of right-hand member 3A through an intermediate passageway 12.

In use, the passageway 6 is connected through an inlet port 13 to an accumulator (not shown) and passageway 6A is connected through a port 14 to a suspension strut or spring (also not shown) so that the valve member 11 controls the flow of fluid between the accumulator and the strut. The upper part of chamber 8A is connected through an exhaust port 15 to a reservoir (not shown) so that valve member 11A controls fluid flow between the suspension strut and the reservoir.

The damper piston 9 is cup-shaped and has a spiral groove 16 around its outer periphery and an aperture 17 in its base. Within the piston 9, is a one-way valve formed by the co-operation of a spring biased closure member 18 and an aperture in an insert 19. A coil compression spring 20 acts between the insert 19 and a plate 21 which is engaged by the valve member 11. A circlip 22 retains the parts within the piston 9.

The base of the piston 9 is engaged by one end of a rod 23 which extends through a guide 24, and engages at its other end an arm 25 of an operating member in the form of a yoke 26. The yoke 26 is rotatably mounted on a rotatable actuating rod 27 and is connected to an actuating member 29 through the intermediary of a coil torsion spring 28 surrounding the rod 27. The actuating member 29 is fast with the rod 27 which extends through a sealed closure 31 and is connected to a lever 32.

In use the valve assembly is mounted on the sprung part of the vehicle and the lever 32 connected to the unsprung part of the vehicle, for example the axle, so that relative movements between the vehicle parts causes movement of the lever 32 to rotate the operating rod 27.

Normally, the valve assembly parts adopt their illustrated positions with both valves 10, 10A closed and the distances between the plates 21, 21A and the respective circlips 22, 22A being equal.

When the vehicle is loaded the lever 32 moves to rotate the rod 27 anti-clockwise as seen in Figure 2. Rotation of the rod 27 is transmitted through the member 29 and the torsion spring 28 to the yoke 26 which causes the piston 9A to move upwardly in the chamber 8A, the valve member 11A being held in its closed position. The piston 9 descends in its chamber 8 under the force of spring 20, fluid being forced along the spiral groove 16 from the lower to the upper part of the chamber 8 to damp motion of the piston 9.

If the vehicle loading is non-transient the piston 9 continues its downward movement until the plate 21 engages the circlip 22 with the spring 20 being caged within the piston 9.

The accumulator fluid pressure is then sufficient to move the valve member 11 to its open position and the strut pressure is increased. As the sprung part of the vehicle rises due to the increased strut pressure the lever 32 returns to its neutral position and the left-hand damper piston 9 is moved upwardly by the rod 23, the one-way valve opening to permit fast undamped return movement of piston 9.

When the vehicle load is removed the lever 32 rotates the rod 27 clockwise to effect movement of piston 9 upwardly and allow the piston 9A to move slowly downwardly to permit the valve 10A to open and release pressure fluid from the strut to the reservoir.

If the vehicle loading is transient, for example due to riding over uneven road surfaces, the pistons 9, 9A will generally not move sufficiently to permit opening of the valves 10, 10A before the lever 32 starts to return to its neutral position. Thus, the fluid pressure in the strut will not change.

Relative movement between the vehicle parts due to fluid leakage will be corrected by downward movement of the left-hand piston 9 to introduce more pressure fluid from the accumulator.

Each valve assembly includes a device for preventing operation of the valves when the side or centrifugal forces exceed a predetermined value. In the illustrated embodiment said device comprises a ball 33, 33A which seats in an elongate, sloping groove 34, 34A formed in the upper surface of the guide 24, 24A. The arrangement illustrated operates only in response to side forces which occur, for example, when negotiating a bend. Side forces which effectively increase the weight on the strut cause the ball 33 to roll up its groove surface and prevent downward movement of the piston 9 sufficient to permit opening of the valve 10. Similarly, side forces which tend to reduce the load on the strut cause the ball 33A to roll up the surface of its groove 34A to prevent opening of the valve 10A.

The ball 33, 33A could be arranged in a dish-shaped recess instead of a groove, in which case forces in the plane of the dish in any direction, including gravitational forces, could prevent opening of the valves 10, l0A. A disadvantage of the last-mentioned arrangement is that the vehicle would not be level when parked on a hill.

The above-described valve assembly has the following advantages: a) the inlet and exhaust valves and damper arrangements are identical, b) the valves and damper arrangements do not have dynamic seals, thus eliminating hysteresis, c) the valve assembly levels the vehicle after only a short time delay when the vehicle is stationary, d) the time delay is increased when travelling over an uneven surface, e) the inlet and exhaust valves do not operate when the valve assembly is subject to centrifugal forces exceeding a predetermined value, f) closure of the inlet exhaust valves is rapid after operation, g) the torsion spring does not act on the damper arrangements so that the damping is independent of severe relative movements between the sprung and unsprung vehicle parts, and h) end plugs 4, 4A are movable to permit adjustment of the valve assemblies.

Attention is directed to our co-pending Patent Application No. 49516/76 (serial no 1559682) WHAT WE CLAIM IS:- 1. A levelling valve assembly for a vehicle suspension system, comprising a normally closed inlet valve for controlling communication between an inlet for pressure fluid and a port for connection to the suspension system, a normally closed exhaust valve for controlling communication between said port and an exhaust opening, each valve having a closure member movable to operate the valve, two damping assemblies, one associated with each valve, wherein each damping assembly is located between its associated valve closure member and operating means, which normally prevents movement of the damping assemblies, said operating means being operable in use in response to vehicle loading to permit movement of one of the damping assemblies and its associated closure member in a direction to open the associated valve, movement of the damping assembly in that direction being damped.

2. An assembly according to claim 1, wherein each damping assembly comprises a damper piston.

3. An assembly according to claim 2, wherein each damper piston works in a chamber on the outlet side of its associated valve.

4. An assembly according to claim 2 or 3, wherein each piston has a spiral path around its periphery, flow of fluid along the spiral path serving to damp the motion of the piston.

3. An assembly according to any of claims 2 to 5, wherein each damping assembly includes resilient means biasing the associated valve closure member towards it valve-closed position.

6. An assembly according to claim 5, wherein the resilient means of each damping assembly is located between the damper piston of that assembly and the associated valve closure member.

7. An assembly according to claim 5 or 6 wherein each damper piston is cup-shaped and the resilient means is located within the damper piston.

8. An assembly according to any of claims 1 to 7, wherein each damping assembly includes a one-way valve which opens to permit relatively undamped movement of the damping assembly to its valve-closed position.

9. An assembly according to any of claims 1 to 8, including means for adjusting the position of each valve relative to the operating means.

10. An assembly according to any of claims 1 to 9, including means for preventing operation of the valves and of the damping means in response to forces other than changes in vehicle loading.

11. An assembly according to any of claims 1 to 10, including energy storing means which prevents the transmission of severe, non-transient movements to the operating means.

12. An assembly constructed and arranged substantially as herein described with reference to the accompanying drawings.

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Claims

**WARNING** start of CLMS field may overlap end of DESC **.

disadvantage of the last-mentioned arrangement is that the vehicle would not be level when parked on a hill.

The above-described valve assembly has the following advantages: a) the inlet and exhaust valves and damper arrangements are identical, b) the valves and damper arrangements do not have dynamic seals, thus eliminating hysteresis,

c) the valve assembly levels the vehicle after only a short time delay when the vehicle is stationary, d) the time delay is increased when travelling over an uneven surface, e) the inlet and exhaust valves do not operate when the valve assembly is subject to centrifugal forces exceeding a predetermined value, f) closure of the inlet exhaust valves is rapid after operation, g) the torsion spring does not act on the damper arrangements so that the damping is independent of severe relative movements between the sprung and unsprung vehicle parts, and h) end plugs 4, 4A are movable to permit adjustment of the valve assemblies.

Attention is directed to our co-pending Patent Application No. 49516/76 (serial no 1559682) WHAT WE CLAIM IS:- 1. A levelling valve assembly for a vehicle suspension system, comprising a normally closed inlet valve for controlling communication between an inlet for pressure fluid and a port for connection to the suspension system, a normally closed exhaust valve for controlling communication between said port and an exhaust opening, each valve having a closure member movable to operate the valve, two damping assemblies, one associated with each valve, wherein each damping assembly is located between its associated valve closure member and operating means, which normally prevents movement of the damping assemblies, said operating means being operable in use in response to vehicle loading to permit movement of one of the damping assemblies and its associated closure member in a direction to open the associated valve, movement of the damping assembly in that direction being damped.
2. An assembly according to claim 1, wherein each damping assembly comprises a damper piston.
3. An assembly according to claim 2, wherein each damper piston works in a chamber on the outlet side of its associated valve.
4. An assembly according to claim 2 or 3, wherein each piston has a spiral path around its periphery, flow of fluid along the spiral path serving to damp the motion of the piston.
3. An assembly according to any of claims 2 to 5, wherein each damping assembly includes resilient means biasing the associated valve closure member towards it valve-closed position.
6. An assembly according to claim 5, wherein the resilient means of each damping assembly is located between the damper piston of that assembly and the associated valve closure member.
7. An assembly according to claim 5 or 6 wherein each damper piston is cup-shaped and the resilient means is located within the damper piston.
8. An assembly according to any of claims 1 to 7, wherein each damping assembly includes a one-way valve which opens to permit relatively undamped movement of the damping assembly to its valve-closed position.
9. An assembly according to any of claims 1 to 8, including means for adjusting the position of each valve relative to the operating means.
10. An assembly according to any of claims 1 to 9, including means for preventing operation of the valves and of the damping means in response to forces other than changes in vehicle loading.
11. An assembly according to any of claims 1 to 10, including energy storing means which prevents the transmission of severe, non-transient movements to the operating means.
12. An assembly constructed and arranged substantially as herein described with reference to the accompanying drawings.