GB2131949A - Automobile headlamp level adjustment - Google Patents

Abstract

A push rod (2) operatively coupled to a headlamp (not shown) is movable in two opposite directions (A) for up and down movement of the headlamp in dependence on the loading of the vehicle. Liquid filled thermal actuators (9, 10), such as bellows actuators, serve to drive the push rod (2) by engagement of their plungers (7, 8) with transverse extensions (3, 4) of the push rod (2) when the liquid therein is heated. Electronic circuitry (not shown) compares information received from a push rod position sensor (23) and the vehicle level sensor (not shown) and when required initiates heating of a respective one of the thermal actuators to drive the headlamp to the appropriate position for the current loading of the vehicle. <IMAGE>

Description

SPECIFICATION Automobile headlamp level adjustment The invention relates to the adjustment of the level of automobile headlamps that is their angle relative to the road surface under conditions of varying load on the axles, particularly the rear axle, and to actuator assemblies for carrying out such adjustment.

According to the present invention there is provided an actuator assembly for selectively moving a member in either of two opposite directions comprising two liquid filled thermal actuators operatively connected to the member, each thermal actuator being effective in a respective one of the opposite directions, means to heat the liquid in the thermal actuators whereby to move the member in one direction when the liquid filling of the associated thermal actuator is heated, and means to hold the member in the position to which it was moved when the liquid is no longer heated.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows partially sectioned an actuator assembly for moving a headlamp in response to a level sensor signal; Figure 2 shows a section through a friction pad assembly, and Figure 3 shows a schematic cross-section through one belows actuator.

In Fig. 1 is illustrated an actuator assembly 1 for providing up and down movement of one or more headlamps (not shown) operatively connected to the right hand end, as viewed in the drawing, of a push rod 2 which is caused to move in the directions indicated by arrow A in response to a level sensor signal, as will be described hereinafter. The push rod 2 has two transverse arms 3 and 4 carrying adjustable tappet-like screws 5 and 6, respectively. The screws 5 and 6 are engageable by plungers 7 and 8, respectively, of respective liquid-filled internally-heatable bellows actuators 9 and 10.

The actuators 9 and 10 are supported in bores of two spaced-apart mounting plates 11 and 12, clamping plate 1 3 of actuator 10 being secured to mounting plate 11 and clamping plate 1 4 of actuator 9 being secured to mounting plate 1 2. The push rod 2 slidably extends through apertures in mounting plates 11 and 1 2 and through a friction pad assembly 1 5 mounted to one of the mounting plates, plate 11 in the embodiment shown in the drawing.The plungers 7 and 8 each carry a respective plunger disc 1 6 and 1 7 and have a respective plunger sleeves 1 8 and 1 9. The plungers 7 and 8 are urged in the direction into the actuators 9 and 10 by tension springs 20 secured between the plunger discs and the furthermost mounting plates. The liquid filling of the bellows actuators may be heated by the application of an electrical supply to the pins 21 and 22, respectively. The position of the push rod 2 is sensed by means, for example, of a position sensor 23 comprising a resistive track potentiometer whose spring loaded wiper 24 is movable by the end 25 of push rod 2.

As shown in Fig. 2, the friction pad assembly 1 5 comprises a housing 26 for a pair of friction pads 27 which are urged together to grip the push rod 2 therebetween, whereby to prevent accidental movement of the rod, by a spring 28.

The principle of operation of the bellows actuators 9 and 10 will now be described with reference to the schematic drawing of one thereof in Fig. 3. A bellows 30 forms the internal wall of a cup shaped chamber 31 which is filled with a liquid 32, such as methanol or a fluorocarbon, which may be heated by a resistive heating element 29. A plunger 33 is a slide fit inside bellows 30, and is urged in contact with the bottom of the cup-shaped chamber 31 by springs, such as 20 (Fig. 1). As described with reference to Fig. 1 the plunger has a sleeve, such as 18 or 1 9 (not specifically shown in Fig. 3), which is of P.T.F.E., for example, and serves to reduce wear on the bellows convolutions.With the heating element 29 actuated, the liquid 32 expands causing contraction of the length of the bellows, thus urging the plunger 33 outwards with respect thereto, causing engagement with the associated screw 6 or 7 (Fig. 1) and corresponding movement to the push rod 2 and thus of the headlamp or lamps connected thereto. When the heating element is no longer supplied with current the liquid 32 rapidly cools and the bellows expand again the plunger being pushed into the chamber by the return springs such as 20. The push rod 2 will, however, remain in the position to which it was driven by virtue of the friction pad assembly.

The bellows actuator assembly shown in Fig. 1 is intended to be used in conjunction with a level sensor on the automobile defining the extent to which the headlamps require adjustment. One such level sensor, which can be fitted to the rear suspension of the automobile, is disclosed in copending Application No.

8204677 (Serial No. )(S.C. Hazon 1). A non-linear coil is attached to the automobile underbody and a ferrite core reciprocable relative the core is attached to the rear axle. The coil forms part of the tuned circuit of a Colpitts oscillator, the frequency of which is directly proportional to the movement of the core relative to the coil. An electronic control circuit is employed to compare information from the automobile level sensor and the headlamp sensor 23 and, if required, issue the necessary signal to one or the other of the bellows heaters to move the headlamps as appropriate. Thus assuming a headlamp required adjustment due to a change in load conditions, the control circuit may be such that a voltage is applied, via a relay contact, to either the "up" or the "down" bellows heater.When the voltage output from the position sensor 23 equates with a voltage determined by the automobile level sensor the operating relay, and therefore the bellows heater, is turned off. Since bellows actuators must always be operated either horizontally or with the heater end down, the separate actuators of the actuator assembly of Fig. 1 must needs be horizontally arranged, or one will be heater end up, in which orientation incorrect operation will result.

The actuator assembly described above may, for example, be employed to drive a single headlamp or both headlamps of a motor vehicle, in the former case a separate actuator assembly will thus be required for each headlamp of the motor vehicle. Whereas bellows actuators have been described other thermally-responsive actuators could alternatively be employed, such as described in our copending Application No. 8021497 (Serial No. 2079452) (T.M. Jackson 70-46-17) and the actuator assembly could be employed to adjust the position of member other than headlamps.

Claims (7)

1. An actuator assembly for selectively moving a member in either of two opposite directions comprising two liquid filled thermal actuators operatively connected to the member, each thermal actuator being effective in a respective one of the opposite directions, means to heat the liquid in the thermal actuators whereby to move the member in one direction when the liquid filling of the associated thermal actuator is heated, and means to hold the member in the position to which it was moved when the liquid is no longer heated.

2. An actuator assembly as claimed in claim 1, wherein the thermal actuators comprise bellows actuators.

3. An actuator assembly as claimed in clain 1 or claim 2, wherein the member is a push rod which is arranged;to operate a member position sensor.

4. An actuator assembly as claimed in claim 3, wherein the axes of plungers of the thermal actuators and the push rod are parallel and wherein the push rod includes transverse projections upon which the plungers are effective for movement of the push rod.

5. An actuator assembly as claimed in claim 3 or 4, wherein the holding means comprises a spring-loaded friction pad assembly effective on the push rod.

6. An actuator assembly as claimed in any one of claims 3, 4 or 5 for use as an automobile headlamp level adjuster, wherein the push rod is operatively coupled for up and down movement of one or more headlamps, including electronic control ciruitry adapted to compare information from the member position sensor and a vehicle level sensor and when required initiate heating of the liquid of a respective one of the thermal actuators in order to correspondingly move the or each headlamp in dependence on the loading of the vehicle.

7. An actuator assembly for an automobile headlamp level adjuster substantially as herein described with reference to and as illustrated in the accompanying drawings.