WO1991007291A1

WO1991007291A1 - Vehicle height adjusting system

Info

Publication number: WO1991007291A1
Application number: PCT/GB1990/001797
Authority: WO
Inventors: Colin Ford Ross
Original assignee: Grau Limited
Priority date: 1989-11-21
Filing date: 1990-11-21
Publication date: 1991-05-30
Also published as: GB8926306D0

Abstract

A vehicle suspension system for a trailer (2) comprises a plurality of suspension units (7). Under the normal operating condition of the suspension system, air is supplied from a source (8) to the suspension units by way of level sensing valves (16 and 18). In accordance with the invention, manually operative control means (20, 30) is provided to override operation of the suspension units (7) by the sensing valve (16 and 18), and to permit manual supply of air to and venting of air from the suspension units (7), to enable the height of the vehicle to be manually adjusted. Means is provided to ensure that the suspension system is returned to its automatic operating condition as a result of the vehicle being driven. In the first embodiment this is afforded by a valve (20) which is switched when the braking system of the vehicle is actuated: in the second embodiment the valve (22) is switched by an electrical signal, which may be obtained from the vehicle tachograph, or from actuation of the vehicle braking light, whilst in the third embodiment the suspension system is returned to its automatic mode in consequence of the unplugging of the manually operative control means (38b) from an inlet socket (34b).

Description

Title : VEHICLE HEIGHT ADJUSTING SYSTEM

Description of Invention

This invention is concerned with improvements relating to vehicle suspension systems, particularly of the kind (hereinafter referred to as being of the kind specified) as may be adjusted by a manual operation whilst the vehicle is stationary, for example to raise or lower the height of a platform provided by the vehicle to assist in loading or unloading. The invention is directed not only to suspension systems of driven vehicles, such as lorries, but also to suspension systems of undriven vehicles such as trailers, where these are independently controllable.

A problem which is prevalent is where a vehicle suspension is so adjustable the vehicle's driver may inadvertently fail to return the suspension to its normal drive position on completion of the loading or unloading operation, and this may result either in damage to the vehicle shock absorbers, or in an instability to the vehicle whilst being driven, or both.

According to this invention there is provided, in or for a vehicle suspension system comprising sensing means automatically operative to sense the height of the vehicle and to control the suspension of the vehicle accordingly, and manually operable means to override the automatic sensing means to enable the suspension to be controlled manually, disabling means to return the suspension system to its automatic mode when the vehicle is driven away from a parked position.

The manually operative means is adapted to be mounted on the trailer, and the disabling means may be actuated in consequence of the vehicle being driven away. Thus the disabling means may be actuated in direct consequence of the vehicle being driven by a means which is responsive to travelling movement of the vehicle, such as may be determined by sensing rotation of the wheels of the vehicle, or sensing movement of the engine or transmission of the vehicle caused by travelling movement of the vehicle.

Alternatively the manually operative means is adapted to be actuated in indirect consequence of travelling movement of the vehicle by a means which is responsive to an event highly likely to occur within a short period of commencement of the vehicle being driven, such as the sensing of a gear change, or the actuation of the vehicle braking system.

Alternatively the manually operative means is adapted to be mounted adjacent to a parking area for the vehicle, and the disabling means may be provided by the requirement for disconnection of the manually operative means from the vehicle suspension system prior to the vehicle being driven away from the parking area.

Preferably the vehicle suspension system comprises valve means movable between

[a] a first position in which delivery of fluid [e.g. air] under pressure to the suspension units is controlled by the sensing means;

[b] a second position in which the fluid is delivered to the suspension units under the control of the manually operative means;

[c] a third position in which the fluid is vented from the suspension units under the control of the manually operative means; and

[d] a fourth position in which flow of fluid to and from the suspension units is prevented.

Thus the manually operative means preferably comprises a manually operated valve which may be actuated to permit the valve means to be moved from its first to one of said second, third and fourth positions and which in consequence of the vehicle being driven is automatically deactivated thereby permitting the valve means to adopt only the first position.

Thus where the manually operative means is mounted adjacent to a parking area, preferably the valve means, in consequence of the manually operative means being connected to the suspension system, is made capable of movement from its first to one if said other positions, and in consequence of disconnection of the manually operative means from the suspension system the valve means is returned to its first position.

According to this invention there is provided a vehicle suspension system comprising a control device which may be manually operated whilst the vehicle is stationary to move the suspension system from a normal operating condition to allow the height of the vehicle to be adjusted, wherein means is provided which is automatically operative to return the suspension system to its normal operating condition (or to one of its normal operating conditions if there are more than one) in consequence of the vehicle being driven.

Said means may be operative in direct consequence of the vehicle being driven: thus said means may be actuated by the sensing of linear movement of the vehicle or the sensing via the vehicle tachograph of a certain speed being reached, or may be operative as an indirect consequence of the vehicle being driven, such as by an event highly likely to occur within a short period of commencement of driving of the vehicle, such as the sensing of a gear change, or an actuation of the vehicle braking system.

According to this invention there is also provided, for use with a vehicle comprising a body, wheels upon which the body is mounted, a suspension system comprising suspension units active between the body and the wheels, and height sensing means operative to sense the height of the body in relation to the wheels and to control the supply of fluid under pressure to the suspension units, fluid being supplied to the suspension units through valve means of the suspension system which is movable between a first position in which delivery of fluid under pressure to the vehicle suspension units is controlled by the sensing means, and a second position in which fluid under pressure is delivered to the suspension units under control of manually operative means, the valve means normally adopting said first position, a manually operative control means for mounting adjacent to a parking area for the vehicle and comprising an output connection means for interfitting with socket means of the vehicle suspension system, wherein the manually operative control means when so interfitted with the socket means provides an output signal for moving the valve means from said first position to said second position.

Preferably the valve means is capable of adopting third and fourth positions, in which under control of the manually operative means fluid is vented from the suspension units, and flow of fluid to and from the suspension units is prevented, respectively.

There will now be given detailed descriptions, to be read with reference to the accompanying drawings, of three forms of execution of the present invention which have been selected for the purposes of illustrating the invention by way of example.

In the accompany drawings:

FIGURE 1 is a schematic view in side elevation of a vehicle with which the present invention is intended for use;

FIGURE 2 is a schematic view showing control means of the invention in a first mode:

FIGURE 3 is a schematic view, corresponding to Figure 2, showing the control means in a second mode; FIGURES 4 and 5 are respectively side elevation and plan views of a manually operative control means of the invention;

FIGURE 6 is a schematic view of a control valve of the invention;

FIGURE 7 is a view of a modification of the invention shown in Figures 1 to 6; and

FIGURE 8 is a schematic view of a circuit diagram of a second embodiment of the invention.

The first embodiment of the invention [Figures 1 to 6] is in the form of a trailer 2 comprising a trailer body 3 supported on three pairs of wheels 4, each wheel 4 being carried on the body by a rearwardly-extending swinging arm 5 carried by a downwardly-extending support member 6 secured to the trailer body, a suspension unit 7 being interposed between the rear of the swinging arm 5 and underside of the trailer body, to provide suspension for the trailer body in relation to the wheels 4.

In the normal operating condition of suspension mechanism of the vehicle, air is supplied from a source 8 to the suspension units 7 through valves 12 and 14 by way of level sensing valve 16 and 18. The valves 12 and 14 are spring urged into their first positions, shown in Figure 2, in which air passing through the valves 16 and 18 via lines Al and A2 pass through a control valve 22, and from thence pass via lines Bl and B2 through the valves 12 and 16 to the units 7.

The suspension system also comprises a manually operative control valve 20 which is normally in the first position, shown in Figure 2. On depression of the valve 20 to the second position, the valves 12 and 14 are moved to their second positions, in which air supplied from the source 8 to the control valve 22 by line C passes to the valves 12 and 14 via lines Dl and D2, to the suspension units 7 under manual control. In this way the level at which the trailer is supported by the suspension system may be adjusted manually, so that the trailer may be positioned [for example in relation to a loading bay] for convenient loading or unloading.

On completion of loading or unloading, normally the valve 20 would be returned to its first position [Figure 2] returning the control of the suspension units to the level sensing valve 16 and 18. However for the event that an operator fails to do this, at an early stage during the use of the trailer, specifically when the brakes are applied, a signal is applied to valve 20 along line E, causing valve 20 to be returned automatically to its first position, so that the vehicle may be driven without damage thereto.

A practical execution of the first embodiment is shown in relation to a manually operative control valve 30 illustrated in Figures 4, 5 and 6. The control valve comprises three inlet lines, inlet line I extending from the reservoir 8. and inlet lines Al and A2 from the sensing control valves 16 and 18, as described in Figures 2 and 3. In this embodiment, lines Bl and Dl have been combined as DB1, and lines B2 and D2 have been combined, as lines DB2, and an additional line X , an exhaust line is shown. The valve 30 is a five position valve, illustrated I-I. The rest position is the medium position III, which the valve adopts during normal use, in which air under pressure fed via the sensing and levelling valves 16 and 18 through lines Al and A2 is delivered direct to the suspension units 7 through lines DBI and DB2

The first position of the valve 30, indicated I, corresponds to lift of the suspension system in which air is fed from the reservoir 8 through line I, to the outlet lines DBI and DB2. In the second position of the valve II, air is prevented from flowing to and from leaving the suspension unit 7, corresponding to a "stop" position.

In the fifth position V of the valve 30, air is exhausted from the lines DBI and DB2 via line X, and a second "stop" position IV is also provided. In this manner an operative may, when the trailer is stationary, manually adjust the height of the trailer, either up or down, and stop it conveniently in a desired position, without having to traverse the rest position III.

On completion of operation, the valve 30 is returned to its rest position, under control of an input from the vehicle along E, as described in relation to Figures 2 and 3.

In the first embodiment, air to the valve 22 or 30 is supplied along line C through limit valve 17, forming part of the level sensing valve 16. Thus valve 17 operates to ensure that when the trailer reaches its maximum height, supply of air through line C to valve 22 is interrupted, preventing the suspension from being lifted above its maximum height.

As an alternative to the valve 20 being returned to its normal position by the application of a signal from the vehicle braking line, if desired control may be exercised by an electronic control unit, such as for example of the kind illustrated schematically in Figure 7.

Thus, in the system illustrated in Figure 7, in which similar numerals with the suffix a have been utilised to indicate like parts, the levelling and lifting valves 16a and 18a may be by-passed by a manual control, permitting the suspension devices 10a to be controlled by a lift/lower control 22a. In the event that the system is not returned to its normal operating position on commencement of driving of the vehicle, an electric signal from the vehicle tachograph, generated when the vehicle speed reaches a predetermined level, is fed through line 25 to the control unit 20, causing the suspension units 10a to be controlled again by the valves 16a and 18a.

Alternative to the use of an electrical signal generated by the vehicle tachograph, an electric signal may be input to the device 22 from the vehicle brake light circuitry, to ensure a return of the suspension system to its operating mode as soon as the vehicle brakes are applied. In the third embodiment, illustrated in Figure 8, the suspension control system comprises a valve 30b through which air is fed from supply 8b through the height controlling sensing valves 16b and 18b to the suspension units 7b, as previously described. However the valve 30b is a five-stage solenoid valve, the position of which is electrically controlled, from a power supply through a junction box 32b, the junction box 32b being provided with an inlet socket 34b. The manually operative control unit 38 is external to the vehicle trailer, and is provided with a connector 40b which may be inserted into the connector 34b, in which it is capable of providing output signals, as generated from the control unit 38b, to control operation of the valve 30b.

The control unit 38b is provided with two buttons, button 42b, visually indicated t to increase the height of the suspension, and button 44b, indicate 4-, to lower the suspension. With the connector 44b connected into the socket 34b, the valve 30b may be moved from its rest position III to any one of four other positions, I, II, IV and V. By depression of the button 42b an electrical signal is applied to the junction box 32b which moves the solenoid valve 30b to its I position, in which air under pressure is fed from the source 8 to both outlet lines DBI and DB2, increasing the air flowing to the suspension units, to raise the suspension. When button 42b is released, the valve moves to its II position, in which the supply of air to and venting of air from the suspension unit 7 is prevented.

Similarly on depression of button 44b the valve 30b adopts V position, in which air is vented via lines X from the suspension units, and upon release of the button 44b, the valve adopts its IV position.

When the connector 40b is withdrawing from the socket 34b, the valve 30b adopts its rest position III, in which the height of the suspension units is controlled by the valves 16b and 18b. In this manner when a vehicle arrives at a loading/unloading bay, the external control unit may be plugged into the junction of the trailer-mounted suspension control system, enabling the operative to adjust the height of the trailer to a desired level. On completion of the loading/unloading operation, and prior to driving away, it will of course be necessary for the operative to disconnect the connector 44b from the socket 34b, this operation causing the valve 30b to adopt its rest position, and ensuring that the trailer is driven away from the loading/unloading bay with the suspension correctly controlled by the levelling/sensing devices 16b and 18b.

In this manner damage to the trailer, and in particular to the shock absorbers thereof, by failure to return the control of the suspension units to thew automatic levelling devices 16b and 18b, is obviated.

It will of course be appreciated that whilst the invention has been described in relation to the control of suspensions of unpowered trailers, the invention may similar be used in relation to control of the suspension units of trucks.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in the terms or means for performing the desired function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS :

1. In or for a vehicle suspension system comprising sensing means automatically operative to sense the height of the vehicle and to control the suspension of the vehicle accordingly, and manually operable means to override the automatic sensing means to enable the suspension to be controlled manually, disabling means to return the suspension system to its automatic mode when the vehicle is driven away from a parked position.

2. The invention according to Claim 1 wherein the manually operative means is adapted to be mounted on the trailer, and the disabling means is actuated in consequence of the vehicle being driven.

3. The invention according to Claim 2 wherein the disabling means is adapted to be actuated in direct consequence of the vehicle being driven by a means which is responsive to travelling movement of the vehicle.

4. The invention according to Claim 2 wherein the manually operative means is adapted to be actuated in indirect consequence of travelling movement of the vehicle by a means which is responsive to an event highly likely to occur within a short period of commencement of the vehicle being driven.

5. The invention according to Claim 1 wherein the manually operative means is adapted to be mounted adjacent to a parking area and the disabling means is provided by the requirement for disconnection of the manually operative means from the vehicle suspension system prior to the vehicle being driven away from the parking area.

6. The invention according to any one of the preceding claims wherein the vehicle suspension system comprises valve means movable between

[a] a first position in which delivery of air under pressure to the suspension units is controlled by the sensing means;

[b] a second position in which air is delivered to the suspension units under the control of the manually operative means;

[c] a third position in which air is vented from the suspension units under the control of the manually operative means; and

[d] a fourth position in which flow of air to and from the suspension units is prevented.

7. The invention according to Claim 6 comprising a manually operative valve which may be actuated to permit the valve means to be moved from its first to one of its second, third and fourth positions and which in consequence of the vehicle being driven is automatically deactivated thereby permitting the valve means to adopt only the first position.

8. The invention according to Claim 6 wherein in consequence of the manually operative means being connected to the suspension system, the valve means is made capable of movement from its first to one of said other positions, and in consequence of disconnection of the manually operative means from the suspension system the valve means is returned to its first position.

9. A vehicle suspension system comprising a control device which may be manually operated whilst the vehicle is stationary to move the suspension system from a normal operating condition to allow the height of the vehicle to be adjusted, wherein means is provided which is automatically operative to return the suspension system to its normal operating condition [or to one of its normal operating conditions of there are more than one] in consequence of the vehicle being driven.

10. For use with a vehicle comprising a body, wheels upon which the body is mounted, a suspension system comprising suspension units active between the body and the wheels, and height sensing means operative to sense the height of the body in relation to the wheels and to control the supply of fluid under pressure to the suspension units, fluid being supplied to the suspension units through valve means of the suspension system which is movable between a first position in which delivery of fluid under pressure to the vehicle suspension units is controlled by the sensing means, and a second position in which fluid is delivered to the suspension units under the control of manually operative means, the valve means normally adopting said first position, a manually operative control means for mounting adjacent to a parking bay for the vehicle and comprising an output connection means for interfitting with socket means of the vehicle suspension system, wherein the manually operative control means when so interfitted with the socket means provides an output signal for moving the valve means from said first position to said second position.