GB2054121A

GB2054121A - A pneumatically operated control device for automatically aligning motor vehicle headlights

Info

Publication number: GB2054121A
Application number: GB8020497A
Authority: GB
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1979-06-26
Filing date: 1980-06-23
Publication date: 1981-02-11
Also published as: IT8048948A0; JPS565233A; GB2054121B; JPS6341774B2; FR2459742A1; DE2925710A1; IT1143971B; FR2459742B1; DE2925710C2

Abstract

Each axle of the vehicle is provided with a respective pressure modulator (15, 16) connected to the intake manifold (21) and in dependence on changes in the distance of a respective axle (18, 20) from the vehicle superstructure the modulators (15, 16) regulate the application of a control pressure to headlight adjusting servomotors (6). Each servomotor (6) contains a working piston (3) which is spring loaded to shorten the illumination range in the event of system failure, the piston (3) being located in the working chamber (5) by a diaphragm (4). The system includes a correction element comprising a pressure modulator (13) connected to manifold (21) and a servomotor (14) which is connected to modulators (15, 16) and causes modulator (13) to feed to each headlight adjusting servomotor (6) a pressure determined by the instantaneous condition of the vehicle suspension. In a modified embodiment modulator 15 is connected to modulator 16 through a simplified correction element and modulator 16 is connected directly to servomotors 6. <IMAGE>

Description

SPECIFICATION Pneumatically-operated control device for the automatic alignment of motor vehicle headlights The invention relates to a pneumaticallyoperated control device for the automatic alignment of motor vehicle headlights, comprising two modulators, one of which is allocated to the front axle and the other one of which being allocated to a rear axle and of each of which, in dependence on the change in the distance of the respective axle to the superstructure of the motor vehicle, generates a control pressure which acts as a control variable and acts on at least one servomotor in such a way as to align the motor vehicle headlight following it to a constant range of illumination.

Such a device is disclosed in German Patent 254644, in which the modulators act on a first servomotor which, itself, acts on a control switch and the latter acts on a further servomotor which brings about the headlight adjustment and simultaneously is connected to this servomotor.

Although it is known through German Auslegeschrift 2163781, to construct the aforementioned adjusting unit, which is interconnected by tubes and straps, much more compactly, the costs for such an adjusting system are still relatively high. For this reason, such automatic systems have not been successful on a larger scale.

This is why manufacturers have proceeded to use only certain parts of such a system, for example the modulators, in manually-operated systems. With these systems it happened time and again, however, that faulty operation led for example to dangerous dazzle and blinding of oncoming traffic.

It is the object of the present invention to provide an automatic headlamp adjusting system of simple construction which has improved operational reliability with favourable production costs. In addition, it should be easily possible to re-equip an already existing manually-operated, pneumatic adjusting system for fully-automatic operation.

According to the invention there is provided a pneumatically-operated control device for the automatic alignment of motor vehicle headlights, comprising two modulators one of which is associated with the front axle of the vehicle and the other being associated with one rear axle, each modulator in dependence on a change in the distance of the respective axle with respect to the superstructure of the motor vehicle, generating a control pressure which acts as a control variable and acts on at least one head light adjusting servomotor in such a way as to align the or each associated headlight to a constant range of illumination wherein each headlight adjusting servomotor is provided with a single working chamber which is divided by a spring-loaded working piston and a diaphragm and the servo pressure fed to each working chamber is matched to the instantaneously-occurring condition of the motor vehicle suspension by means of correction element which is disposed in the pneumatic system before the modulators generating the headlight adjusting servo pressure.

In this way it is possible to achieve reliable dual axle control with the use of the simplest servomotors.

In one embodiment of the invention, the correction element is constructed as a doubleacting servomotor of tandem construction, the working chambers of which, which are arranged in the same direction, are loaded by the modulated pressure of the respective associated modulator, the switching movements of the correction element being utilized directly for actuating the further modulator generating the servo pressure for changing the range of illumination. This embodiment offers the greatest possible freedom in the selection of where to accommodate the correction element and the subsequent modulator.

Advantageously the modulator generating the servo pressure and the correction element form one constructional unit.

In a further advantageous embodiment of the invention, the correction element is formed by a single-action servomotor which is arranged as part of a device which senses the supension movement of the associated axle, and which changes the effective length of this device when responding.

In a further embodiment of the invention, the modulator and the associated correction element form a single constructional unit and the correction element represents a single-action servomotor, the switching movements of which are transmitted directly to the attached modulator.

Two embodiments of the invention will now be explained in greater detail by way of example and with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of a first embodiment of the invention having a correction element in the form of a double-acting servomotor, and Figure 2 is a schematic illustration of a further embodiment of the invention having a singleaction servomotor as the correction element which is arranged as part of a device which senses the movements of the suspension of the associated axle.

As shown in Figure 1, a motor vehicle has headlights 1, each of which is housed or encapsulated in a lighting unit, not shown, with a reflector 2 which is pivotally supported and one of which-as shown in partial section-is connected to a spring-loaded working piston 3. Together with a diaphragm 4, this piston divides a working chamber 5 in a servomotor 6. Each servomotor 6 is accommodated by a pivoted holder 7 which has at its upper end 8 an adjusting device 9 for the basic setting of the associated reflector 2. The two working chambers 5 are linked with each other by a line 10. From this line a further line 11 branches off and leads to the outlet 12 of a modulator 13 which, together with a double-action servomotor, representing a correction element 14, forms one constructional unit in tandem construction.

Apart from the modulators 13, two further modulators 15 and 16 are provided, all of which are basically constructed the same way. In this arrangement, the modulator 1 5 is allocated through a rod arrangement 17 to the front axle 18 and the modulator 1 6 is connected, also by a rod arrangement 19, to the rear axle 20. All three modulators are fed by a vacuum obtained from the intake manifold 21 of an internal combustion engine, (not shown). In a line 22 which leads away from the suction pipe 21 a non-return valve 23 and a storage reservoir 24 are provided. These elements can be omitted if a pump, not shown, acts as the supplier of the vacuum. From the line 22 a first branch line 25 leads to the inlet 26 of the modulator 15 and a second branch line 27 leads to the inlets 28 and 29 of the modulators 13 and 16, respectively.

Each of the modulators 13,15 and 16 is provided with a floating plate 30 which carries on its side facing away from the outputs 1 2, a sealing disc 31 and which, during pauses, rests both against the plate 30 and against the outlet side of the respective inputs 26, 28 and 29 so that an annular gap 32 located between these inlets and the respective associated plate 30 is covered. This construction separates two chambers 33 and 34 from each other, the latter being connected to atmosphere.

If the suspension of the front axle 1 8 is compressed, a feeler 36 of the modulator 1 5, which is loaded by a control spring 35 and which rests against the rod linkage or arrangement 1 7 is moved upward by the rod linkage or arrangement 1 7 connected to the suspension, which leads to an upward movement of the plate 30. The sealing disc 31 continues to rest against the plate 30 so that a connection is created via the annular gap 32 from the chamber 33 to the inlet 26. Now the pressure in the chamber 33 is lowered until the plate 30, moving back against the pressure of the control spring 35, is in that same plane as the suction intake and the sealing disc 31 seals off the chamber.

If the suspension of the front axle 1 8 lengthens again, the plate 30 moves downward. Since the sealing disc 31 continues to cover the suction air intake, a connection is made through the annular gap from chamber 33 to chamber 34. Accordingly, the vacuum in the chamber 33 decreases until the plate 30, moving back to its initial position, comes to rest against the sealing disc 31.

The reduced pressure which occurs in the chamber 33 of the modulator 1 5 when the suspension of the front axle 1 8 is compressed, is transmitted through a line 37 to a working chamber 38 of the servo-motor correcting element 14 to which the modulator 13 is connected, so that a piston 41, which is loaded by a spring 39 and is supported by a diaphragm 40 to float with respect to the servo-motor housing.

moves to the right (as seen in Figure 1). Since this piston is connected to the plate 30 of the modulator 13, the plate 30 also moves to the right so that the pressure in the associated chamber 33 is lowered in the same manner as has been described for the modulator 1 5. This increased vacuum is communicated through the lines 11 and 10 to the working chambers 5 of the servomotor 6 which causes the working pistons 3 to be moved against the force of a spring 42-which moves the reflectors 2 into a lower or more dippled position if the system fails-to the right.

This causes each reflector 2 to be tilted backwardly, increasing the range of illumination.

If, on the other hand, the suspension of the front axle 1 8 recovers or lengthens again, the decreasing vacuum causes the piston 41 of the correction element 14 to move to the left, producing a lower value of vacuum in the chamber 33 of the modulator 13 which, in turn, causes the working pistons 3 to move to the left. The consequence of this is that the associated reflectors 2 tilt forward.

Due to the fact that, in contrast to the front axle 18, the modulator 16 for the rear axle 20 is installed in the reverse sense, the vacuum is lowered if the suspension of the rear axle is compressed, so that this value is transmitted through a line 43 to a rear working chamber 44 of the servo-motor 14 which is arranged in tandem with the working chamber 38. Since the piston 41 also actuates a clamped diaphragm 45 in the working chamber 44 by means of a stem, the piston 41 moves to the left so that the range of illumination is reduced in the abovementioned manner. It can now easily be seen that, if the suspension of the rear axle 20 recovers or lengthens, the range of illumination increases.

If parallel suspension movements occur at both axles, the value of the vacuum, for example, in the working chamber 38 rises to the same extent that it decreases in the working chamber 44 so that the piston 41 is not displaced due to the fact that the piston areas are calibrated with respect to each other to ensure this balance.

If unequal suspension movements occur at both axles, the piston 41 is displaced proportionally in accordance with the pressure changes produced in the working chambers 38 and 44.

Compared to the embodiment of Figure 1, the embodiment illustrated in Figure 2 has a number of similar parts for which the same reference are used. The servomotor correction element 14 in this embodiment is constructed as a single-action servomotor which has a working chamber 46, which is closed at one end by a spring-loaded diaphragm 46 and which is connected on one side by a line 48 to the outlet 49 of the modulator 1 5 for the front suspension 1 8. The rod arrangement or linkage 19, into the section leading away from the rear axle 20 of which the correction element 14 is inserted, represents an arrangement 50 which senses the suspension movements of the rear axle 20 and communicates them to the feeler 36 of the rear suspension modulator 1 6.

If the suspension of the front axle 1 8 is compressed, the value of the vacuum in the associated chamber 33 of the modulator 15 increases and, accordingly increases also in the working chamber 47 of the correction element 1 4 so that the part facing the rear axle 20 of the rod arrangement 1 9 is shortened. The result of this is that the plate 30 of the modulator 16 moves downward and the value of the vacuum in its chamber 33 increases. The working pistons 3 of the headlamp adjusting servomotors 6 consequently move to the right and tilt the reflectors back to increase the range of illumination. If the suspension of the front axle 1 8 expands again, the abovementioned process is reversed and the range of illumination is correspondingly reduced.

With suspension movements of the rear axle 20 the correction element 14 does not come into play and with parallel suspension movements of both axles, the effective length of the rod arrangement 19 near the axle is shortened or lengthened so that the suspension movements of the rear axle 20, which are in the same direction and of the same magnitude, do not trigger a control process.

An adjustment of the range of illumination is initiated, in accordance with the resultant inclination of the vehicle about a transverse vehicle axis, only if the suspension movements differ.

The modulator 1 6 and the correction element 14 could be combined into one constructional unit in a manner not shown, in which case the switching movements of the correction element 14 are transmitted directly to the modulator 1 6.

Claims

1. A pneumatically-operated control device for the automatic alignment of motor vehicle headlights, comprising two modulators, one of which is associated with the front axle of the vehicle and the other being associated with one rear axle, each modulator in dependence on a change in the distance of the respective axle with respective to the superstructure of the motor vehicle, generating a control pressure which acts as control variable and acts on at least one headlight adjusting servomotor in such a way as to align the or each associated headlight to a constant range of illumination, wherein each headlight adjusting servomotor is provided with a single working chamber which is divided by a spring-loaded working piston and a diaphragm and the servo pressure fed to each working chamber is matched to the instantaneouslyoccurring condition of the motor vehicle suspension by means of a correction element which is disposed in the pneumatic system before the modulators generating the headlight adjusting servo pressure.

2. A control device according to Claim 1, wherein the correction element is constructed as a double-acting servomotor in tandem construction, the working chamber of which, which are arranged coaxially, are loaded by the modulated pressure of the respective associated axle modulator, and the switching movements of the correction element are utilized directly for actuating a further modulator generating the servopressure for changing the range of illumination.

3. A control device according to claim 2 wherein the modulator generating the control pressure and the connection element are combined into a single unit.

4. A control device according to any one of claims 1 to 3, wherein the correction element is formed by a single-action servomotor which is arranged as part of a device which senses the suspension movement of the associated axle, and which changes the effective length of this device when responding to suspension movement.

5. A control device according to any one of Claims 1 to 4, wherein the modulator for one axle and the associated correction element form a single constructional unit and the correction element represents a single-action servomotor the switching movements of which are transmitted directly to the associated modulator.

6. A pneumatically operated control device for the automatic alignment of motor vehicle headlights substantially as hereinbefore described with reference to the accompanying drawings.