WO2008051117A1

WO2008051117A1 - A horn-actuator and a safety arrangement for a motor vehicle comprising a horn-actuator

Info

Publication number: WO2008051117A1
Application number: PCT/SE2006/001201
Authority: WO
Inventors: Thierry Hondier; Rémi BAILLIVET; Stéphane MAURIN
Original assignee: Autoliv Development Ab
Priority date: 2006-10-25
Filing date: 2006-10-25
Publication date: 2008-05-02
Also published as: JP2010507529A; DE112006004085T5; KR101332732B1; JP4870214B2; DE112006004085B4; KR20090071615A

Abstract

A horn-actuator is disclosed for use with a steering-wheel mounted air-bag module in a motor vehicle and is configured to releasably mount a cover of the air-bag module for movement relative to the structure of the steering-wheel. The horn-actuator is configured for movement from an initial position, through an actuating position and on to a release position such that a pair of horn-contacts are closed in the actuating position. Biasing means are provided so as to provide a first biasing force against which the actuator is moved from its initial position to its actuating position, and to provide a second, higher, biasing force against which movement from the actuating position to the release position acts.

Description

A HORN-ACTUATOR AND A SAFETY ARRANGEMENT FOR A MOTOR VEHICLE COMPRISING A HORN-ACTUATOR

Description of Invention

THE PRESENT INVENTION relates to a horn-actuator for use with a steering- wheel-mounted air-bag module in a motor vehicle, and also relates to a safety arrangement for a motor vehicle comprising such a horn-actuator.

It has been proposed previously to provide a so-called "driver's air-bag" in a motor vehicle for deployment, in the event of a crash situation, to offer a level of protection to the driver of a motor vehicle. Such drivers' air-bags are typically provided, initially packed prior to deployment, in an air-bag housing mounted in the region of the central hub of the steering wheel of the motor vehicle.

Typically, an air-bag cover is provided which attaches to the air-bag housing in order to cover the housing. The cover is generally designed to present a consistent and attractive external appearance, blending in with the remainder of the steering-wheel, thereby giving a neat, "finished" appearance to the overall steering-wheel assembly. The air-bag cover may nevertheless be configured to allow deployment of the air-bag from within the air-bag housing. For example, the air-bag cover may typically be provided with one or more "split-lines" which together form a break-away panel or door in the cover, thereby allowing deployment of the air-bag through the cover during a crash situation.

It has also become increasingly common for at least a portion of the air-bag cover to be designed so as to have the dual purpose of providing both an aesthetically pleasing outward appearance, whilst also functioning as a push- button for the vehicle's horn, thereby allowing easy actuation of the vehicle horn in an emergency situation. In such arrangements, the air-bag cover is typically mounted to the air-bag housing by means of one or more spring elements, and the cover and housing are additionally hooked to one another. Thus, the cover effectively "floats" on the housing and the cover may be depressed towards the housing, against the bias of the spring elements, to close horn-contacts forming part of the horn circuit, thereby actuating the vehicle horn. Upon release of the cover after being depressed, the spring elements are arranged to return the cover to its initial position prior to depression, whilst the hooking engagement between the cover and the housing ensures that the cover and housing do not become disconnected as the cover returns to its initial position from its "actuating" position in which the horn-contacts are closed.

In order to ensure that pressing of the cover in order to actuate the horn does not also allow the cover and housing to become inadvertently unhooked from one another, arrangements of this sort are configured such that movement of the cover towards the housing to actuate the horn is nevertheless insufficient to allow unhooking of the cover from the housing (and therefore is insufficient to allow the cover and housing to be hooked to one another in the case where the cover and housing are initially separate during assembly). Thus, during assembly of the arrangement, the cover and housing must first be hooked together and the horn assembly subsequently mounted between the cover and housing. Mounting of the horn assembly between the cover and housing in this manner can be relatively complicated and difficult to achieve in practice, and can therefore be undesirably time-consuming and expensive on the production line.

It is an object of the present invention to seek to provide an improved horn- actuator and an improved safety arrangement for a motor vehicle comprising a horn-actuator. Accordingly, a first aspect of the present invention comprises a horn-actuator for use with a steering-wheel-mounted airbag module in a motor vehicle and configured to releasably mount a cover of the airbag module for movement relative to the structure of the steering wheel, wherein the horn actuator comprises: a pair of electrical horn-contacts, and a moveable element configured to move in response to movement of the cover, the moveable element being arranged for movement from an initial position through an actuating position and on to a release position, the moveable element being configured to close the horn-contacts when moved from its initial position to its actuating position, wherein the actuator further comprises biasing means configured to bias the moveable element from its actuating position to its initial position with a first biasing force, and from its release position to its actuating position with a second biasing force, the second biasing force being greater than the first biasing force.

Preferably, the moveable element is arranged for linear movement along a single predetermined axis.

Advantageously, said biasing means comprises a pair of springs.

Conveniently, a first of said springs is arranged to provide said first biasing force and a second of said springs is arranged it provide said second biasing force.

Preferably, the first spring is arranged to deform resiliently during movement of the moveable element from its initial position to its actuating position, and the second spring is arranged to deform resiliently during movement of the moveable element from the actuating position to the release position but not to deform during movement of the moveable element from the initial position to the actuating position. Advantageously, said second spring has a higher spring constant than said first spring.

Conveniently, each of said springs is substantially helical in form.

Preferably, each of said springs is a compression spring.

Advantageously, said springs are arranged concentrically.

Conveniently, said moveable element has a contact surface configured for contact with part of the cover of the airbag module.

Preferably, said horn-contacts are mounted in spaced-apart relation to one another, and wherein said moveable element carries an electrically conductive element arranged to electrically interconnect the horn-contacts when the moveable element adopts its actuating position.

Advantageously, said electrically conductive element is slidably mounted on said moveable element and wherein said second spring is configured to act between part of the moveable element and the conductive element to urge the conductive element against a stop provided on the moveable element.

Conveniently, the horn-actuator comprises a housing within which said moveable element is mounted for sliding movement in the manner of a piston.

Preferably, said first spring is arranged to act between part of said moveable element and part of the housing, so as to bias them away from one another. According to a second aspect of the present invention, there is provided a safety arrangement for a motor vehicle comprising a horn-actuator as defined above provided in combination with an airbag module, the airbag module comprising a housing configured to be mounted to a steering wheel, wherein the horn actuator is arranged to releasably mount the cover to the housing for movement relative to the housing, the arrangement being such that removal of the cover from the housing, or attachment of the cover to the housing, is prevented unless the moveable element is moved to its release position by pressing the airbag cover towards the housing.

Preferably, the actuator housing is formed as an integral part of the module housing.

Advantageously, the actuator housing and the module housing are moulded from plastics material as a single unit.

Conveniently, said actuator housing is formed separately from the module housing, but wherein the actuator housing is secured to the module housing.

So that the invention may be more readily understood, and so that further features thereof may be appreciated, embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:-

FIGURE 1 is a perspective view from below, showing a first embodiment of a safety arrangement according to the present invention;

FIGURE 2 is a large perspective view of a horn-actuator forming part of the present invention; FIGURE 3 is a schematic cross-sectional view illustrating the safety arrangement in an initial condition;

FIGURE 4 is a view corresponding generally to that of Figure 3, but illustrating the safety arrangement in a horn-actuating condition;

FIGURE 5 is a view corresponding generally to that of Figure 4, but illustrating the safety arrangement in a release condition; and

FIGURE 6 is a perspective view from below of a safety arrangement in accordance with the present invention, illustrating a preferred form of electrical connection to the horn-actuator.

Figure 1 shows a safety arrangement incorporating an air-bag module 1 comprising an air-bag housing 2 configured to contain an initially folded air- bag (not shown), and an air-bag cover 3.

As can be seen from Figure 1 , the specific external shape of the air-bag housing 2 is somewhat complex, to enable the housing 2 to accommodate various components associated with deployment and control of the air-bag.

A detailed description of the specific shape of the housing 2 is not necessary for a full understanding of the present invention. Nevertheless, it will be noted that the housing 2 has a generally triangular configuration and incorporates a mounting base 4 which allows the housing 2 to be mounted to the structure of given steering wheel (not shown). The housing

2 also comprises two pairs of downwardly-directed hook-elements 5 (of which only one pair can be seen clearly in Figure 1), provided on respective side walls 6 of the housing.

The air-bag cover 3 comprises a generally tri-lobal planar body portion 7 which defines three lobes 8, and a pair of side walls 9 (of which only one is shown clearly in Figure 1 ). Each side wall 9 extends downwardly from the periphery of the body portion 7 between a respective pair of lobes 8, and comprises a pair of generally rectangular apertures 10 which are sized and shaped to receive respective hook elements 5 therethrough as a snap-fit to secure (preferably releasably) the cover 3 to the housing 2. It should be appreciated that, with the hook elements 5 engaged with the lower edges of the respective apertures 10, the cover 3 and the housing 2 are prevented from being pulled apart from one another.

The cover 3 is preferably formed of a suitable plastics material, and is most preferably formed to match the relevant steering wheel on which the housing is mounted. In this manner, it will be appreciated that the lobes 8 of the cover are configured such that when the housing 2 is mounted td the central hub of a suitable steering wheel frame comprising three spokes, the lobes 8 will align with the spokes to create a neat finish to the hub region of the steering wheel.

Still referring to Figure 1 , the safety arrangement is further provided with three substantially identical horn-actuator arrangements, of which two are indicated generally at 11 in Figure 1 (the third horn-actuator being obscured in Figure 1 by the housing 2). Figure 2 illustrates one of the horn-actuators in further detail. However, still referring to Figure 1 , it is to be noted that the underside of the air-bag cover 3 is provided with three downwardly-depending projections 12, of which two are visible in Figure 1 (the third projection 12 being obscured in Figure 1 by the housing 2). Each projection 12 is aligned with a respective horn-actuator 11 and is arranged to extend towards the horn-actuator 11 in order to operate the horn- actuator as the air-bag cover 3 is pressed towards the structure of the steering-wheel as will be described hereinafter in more detail. It should be noted that although the preferred embodiment described herein is provided with three horn-actuators 11 and three corresponding cover projections 12, in variants of the invention alternative numbers of horn-actuators and corresponding cover projections 12 could be provided. For example, it is envisaged that alternative embodiments of the present invention could be provided with only two horn-actuators 11 and corresponding cover projections 12. It is even possible for a safety arrangement to be provided with only one horn-actuator 11 and a corresponding single cover projection 12.

Turning now to consider Figure 2, features of the horn-actuator 11 will be explained in more detail.

The horn-actuator 11 comprises a hollow, generally cylindrical housing 13 (shown cut-away in Figure 2 so as more clearly to illustrate the internal components contained within the housing 13). The housing 13 is open at its upper end 14 but closed at its lower end 15 by an end wall 16. The end wall 16 provided at the lower end 15 of the housing is provided with a central aperture 17.

As can be clearly seen from the cut-away view of the housing 13 in Figure 2, the housing, although generally cylindrical in configuration, is stepped so as to define an inwardly-extending peripheral shoulder 18 which defines an upwardly-directed bearing surface 19 of generally annular form.

The housing 13 is preferably moulded from plastics material and is secured to the housing 2 of the air-bag module 1. The housing 13 can be secured to the air-bag module in any one of a number of convenient ways. For example, the actuator housing 13 can be formed as an integral part of the air-bag housing 2, for example by moulding both parts from plastics material as a single unit. Alternatively, the horn-actuator housing 13 can be formed as separate unit from the air-bag housing 2 and subsequently attached to the air-bag housing 2 such as, for example, by way of rivets or a snap-fit arrangement.

The inwardly-stepped nature of the housing 13 thus defines an interior chamber of the housing having two distinct regions. A first lower chamber region 20 is defined below the shoulder 18, and a second upper chamber region 21 is defined above the shoulder 18. Both chamber regions 20, 21 are generally cylindrical in form.

A pair of electrical horn-contacts 22 are provided at the lower end 15 of the housing. The horn-contacts 22 each extend through the end wall 16 on opposed sides of the central aperture 17. The horn-contacts 22 preferably take the form of metal rivets or the like and each define an upwardly- directed contact surface 23 within the lower chamber region 20, spaced a short distance above the uppermost surface of the end wall 16. The regions of the electrical contacts 22 extending downwardly from the outer surface of the end wall 16 define connections for electrical connection with respective lugs 24 (illustrated in Figure 1), which in turn are electrically connected to wires 25 of an electric horn circuit.

Provided within the housing 13 is a moveable element 26 which is provided for movement within the housing 13 in the manner of a piston. The moveable element 26 has a generally circular head portion 27 which defines an upwardly-directed contact surface 28 which is arranged for contact with a respective cover projection 12 (as illustrated in Figure 1). The external dimensions of the head 27 are such that the head is received as a sliding fit within the upper chamber region 21 defined within the housing 13. Extending downwardly from the head 27, the moveable element 26 further comprises a central cylindrical portion 29. At its lowermost end 30, the central cylindrical portion 30 carries a short element 31 having a pair of opposed flat faces 32. At its lowermost end, the flat-sided element 31 carries an end piece 33 of generally circular form and having an external dimension corresponding generally to the diameter of the central aperture 17 formed through the end wall 16. The end piece 33 carries a pair of opposed downwardly-depending arms 34, each of which is resiliently deformable. Each arm 34 carries an outwardly-directed projection 35 at its lower end.

The moveable element 26 is held captive within the housing 13 by way of the deformable arms 34 and their respective outwardly-directed projections In order to assemble the horn-actuator, the moveable element 26 is inserted into the housing from the upper end 14 such that the arms 34 are pressed through the aperture 17 formed in the end wall 16. Ramp surfaces 36 formed on the outwardly-directed projections 35 serve to urge the resiliently-deformable arms 34 inwardly as the moveable element is pressed downwardly against the end wall 16. When the arms 34 become inserted through the aperture 17 to a sufficient extent, the outwardly- directed projections 35 clear the aperture 17 whereupon the arms 34 return to their natural unbiased condition illustrated in Figure 2 such that the outwardly-directed projections 35 serve to retain the moveable element 26 captive within the housing 13, but allowing for downwards slidable movement within the housing.

An electrically-conductive element 37 is provided on the moveable element 26 and preferably takes the form of a generally C-shaped washer made of metal material. The C-shaped washer is provided around the flat-sided element 31 of the moveable element 26 and is thus mounted for slidable movement along the flat-sided element 31 between the end piece 33 and the lower end 30 of the central cylindrical portion 29. The flat faces 32 provided on the flat-sided element 31 prevents rotational movement of the electrically-conductive element 37.

As will now be described in more detail, the horn-actuator 11 is provided with biasing means which comprises a pair of springs.

A first spring 38 is provided around the central cylindrical portion 29 of the moveable element 26 and takes the form of a helically-wound compression spring having a diameter such that the spring is received within the upper chamber region 21 , with its lower end bearing against the upwardly- directed bearing surface 19 defined by the shoulder 18, and so that its upper end bears against the undersurface of the head 27 of the moveable element 26. The first spring 38 thus serves to bias the moveable element 26 to its initial position illustrated in Figure 2, but allows axial movement of the moveable element 26 downwardly along the axis A, such movement serving to compress the spring, the spring thus providing a first biasing force resisting downwards movement of the moveable element 26.

A second spring 39 is also provided around the central cylindrical portion 29 of the moveable element 26. The second spring is again a helically- wound compression spring but has a smaller diameter than the first spring 38, such that the second spring 39 is received within the first spring 38, with the two springs being arranged concentrically. The lower end of the second spring 39 bears against the upper surface of the electrically- conductive element 37, whilst the upper end of the second spring 39 bears against the undersurface of the head 27 of the moveable element 26. The second spring 39 thus serves to urge the electrically-conductive element 37 downwardly, against the end piece 33, which effectively defines a stop. The second, inner, spring 39 is stronger than the first spring 38 and thus has a higher spring constant than the first spring 38.

Turning now to consider Figures 3, 4 and 5, the operation of the safety assembly shown in Figures 1 and 2 will now be described. It is to be noted that Figures 3, 4 and 4 are intended only as schematic representations illustrating the operation of the safety arrangement in accordance with the present invention. Thus, certain features shown in Figures 1 and 2 have been greatly simplified or stylised for clarity in Figures 3, 4 and 5. In particular, in Figures 3, 4 and 5, the pair of hook elements 5 are shown in the same cross-section plane as the horn assembly 11 , in contrast to the actual relative positions of these components as illustrated in Figures 1 and 2.

Referring initially to Figure 3, the safety arrangement is shown, in part, prior to depression of the cover 3 to activate the horn. In this position, it will be seen that the moveable element 26 adopts an initial position in which it is biased upwardly relative to the housing 13.

In order to activate the horn, a vehicle occupant will depress the cover 3, as indicated by the arrow A in Figure 3. Upon such depression of the cover 3, the cover projection 12 pressed down on the contact surface 23 of the moveable element 26 and thus serves to depress the moveable element 26 within the housing 13, against the biasing force of the first spring 38. Downwards movement of the cover 3, and the moveable element 26 continues, with consequent compression of the first spring 38, until such point as the electrically-conductive element 37 has been moved downwardly by distance x so as to bear against the two horn-contacts 22 as illustrated in Figure 4. Figure 4 thus illustrates an intermediate, actuating position, of the moveable element 26 in which the electrically-conductive element 37 carried by the moveable element 26 serves to close the electrical horn- contacts 22, thus completing the horn circuit to sound the vehicle horn. As can be seen from the drawings, because the initial vertical spacing of the electrically-conductive element 37 above the horn-contacts 32, represented by x, is less than the vertical extent of the hook elements 5, movement of the cover 3 from the initial position in Figure 3, to the actuating position in Figure 4 is insufficient to allow the hook elements 5 to become unhooked from the apertures 10 formed in the cover and so during normal actuation of the horn, the cover 3 remains secured to the air-bag housing 2.

Figure 5, on the other hand, illustrates operation of the safety arrangement specifically to allow un-hooking of the cover 3 from the housing 2.

Thus, in the case where it is specifically desired to un-hook the cover 3 from the housing 2, sufficient downward force (greater than any force associated with normal operation of the vehicle horn as described above) may be applied to the cover 3 to press the moveable element 26 downwardly against the higher biasing force provided by the second spring

39. As the cover 3 is depressed in this manner, the second spring 39, which is stronger than the first spring 38 is also caused to compress, along with the first spring 38, thus allowing the moveable element 26 to move further downwards. The electrically-conductive element 37, under the action of the second spring 39, remains in contact with the two horn- contacts 22, but by virtue of its sliding engagement on the flat-sided element 31 , the moveable element 26 is allowed to slide through the electrically-conductive element to adopt the release position illustrated in Figure 5 in which the lower end 30 of the central cylindrical portion 29 bears against the electrically-conductive element 37. As can be seen from

Figure 5, as the moveable element 26 is moved through its actuating position illustrated in Figure 4, so as to assume its release position illustrated in Figure 5, the result is that the air-bag cover 3 has been depressed by a distance sufficient for the lower edges of the apertures 10 to clear the lower edges of the respective hook elements 5 so that the hook elements 5 may then be withdrawn through the respective apertures 10 to unhook the cover 3 from the housing 2. Unhooking of the cover 3 from the housing 2 in this manner allows disconnection of the cover 3 from the housing 2.

The present invention thus provides an arrangement whereby initial depression of the air-bag cover 3 against a first biasing force (provided by the first spring 38) is sufficient only to allow actuation of the horn, whilst further depression of the air-bag cover 3 against a second, higher, biasing force (provided by the second spring 39) is sufficient to allow the cover 3 to be unhooked from the air-bag housing 2.

It is to be appreciated that, although the operation of the safety arrangement illustrated in Figures 1 to 5 has been described with reference to disconnection of the cover 3 from the housing 2, the safety arrangement shown in Figures 1 to 5 would equally permit convenient assembly of the cover 3 to the housing 2.

Thus, where it is desired to mount the cover 3 to the housing 2, the cover 3 may first be resiliently-mounted on the housing 2 by locating the cover projections 12 against respective contact surfaces 23 provided on top of the moveable element 26 such that the cover effectively "floats" on the housing. The cover 3 may then be depressed towards the housing 2 in the manner described above, using sufficient force to adopt the position illustrated in Figure 5, thus depressing both the first spring 38 and the second spring 39, whereupon the cover 3 and the housing 2 may be conveniently hooked to one another by the hook elements 5 and the respective apertures 10. Once the cover 3 and the housing 2 have been hooked together in this manner, the cover 3 may then be released so as to adopt the position illustrated in Figure 3 after which time the safety arrangement may be operated in accordance with Figures 3 to 5.

Although the invention has been described above with reference to a specific embodiment, certain modifications could be made without departing from the scope of the invention. For example, whilst the embodiment described above employs a pair of horn-contacts 22 which form part of the electrical horn circuit by electrical connection with a series of wires 25, it is envisaged that in a variant of the invention illustrated schematically in Figure 6, this arrangement could be altered. In the arrangement illustrated in Figure 6, the electrical wires have been dispensed with and instead a series of bus-bars 40 are provided which could be moulded into the structure of the air-bag housing 2. In such an arrangement, it is envisaged that the bus-bars 40 could be arranged to make direct electrical contact with the electrically-conductive element 37 provided within the horn-actuator mechanism, thereby effectively eliminating the specific horn-contacts 22 described above. In such an arrangement, the free ends 41 of the bus-bars 40 could be moulded into the housing 13 of the horn-actuator 11 and would thus, themselves, effectively define electrical horn-contacts to be closed by the electrically-conductive element 37 on actuation of the horn-actuator mechanism.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A horn-actuator (11) for use with a steering-wheel-mounted airbag module in a motor vehicle and configured to releasably mount a cover (3) of the airbag module for movement relative to the structure of the steering wheel, wherein the horn actuator (11) comprises: a pair of electrical horn-contacts (22), and a moveable element (26) configured to move in response to movement of the cover (3), the moveable element (26) being arranged for movement from an initial position through an actuating position and on to a release position, the moveable element (26) being configured to close the horn- contacts (22) when moved from its initial position to its actuating position, wherein the actuator further comprises biasing means (38,39) configured to bias the moveable element from its actuating position to its initial position with a first biasing force, and from its release position to its actuating position with a second biasing force, the second biasing force being greater than the first biasing force.

2. A horn actuator according to claim 1 , wherein the moveable element (26) is arranged for linear movement along a single predetermined axis (A).

3. A horn actuator according to claim 1 or claim 2, wherein said biasing means comprises a pair of springs (38,39).

4. A horn actuator according to claim 3, wherein a first of said springs (38) is arranged to provide said first biasing force and a second of said springs (39) is arranged it provide said second biasing force.

5. A horn actuator according to claim 4, wherein the first spring (38) is arranged to deform resiliency during movement of the moveable element (26) from its initial position to its actuating position, and the second spring (39) is arranged to deform resiliently during movement of the moveable element (26) from the actuating position to the release position but not to deform during movement of the moveable element (26) from the initial position to the actuating position.

6. A horn actuator according to claim 4 or claim 5, wherein said second spring (39) has a higher spring constant than said first spring (38).

7. A horn actuator according to any one of claims 3 to 6 wherein each of said springs (38,39) is substantially helical in form.

8. A horn actuator according to claim 7, wherein each of said springs (38,39) is a compression spring.

9. A horn actuator according to claim 7 or 8, wherein said springs (38,39) are arranged concentrically.

10. A horn actuator according to any preceding claim, wherein said moveable element (26) has a contact surface (28) configured for contact with part (12) of the cover (3) of the airbag module.

11. A horn actuator according to any preceding claim, wherein said horn-contacts (22) are mounted in spaced-apart relation to one another, and wherein said moveable element (26) carries an electrically conductive element (37) arranged to electrically interconnect the horn-contacts (22) when the moveable element (26) adopts its actuating position.

12. A horn actuator according to claim 11 as dependant upon any one of claims 4 to 9, wherein said electrically conductive element (37) is siideably mounted on said moveable element (26) and wherein said second spring (39) is configured to act between part of the moveable element (27) and the conductive element (37) to urge the conductive element (37) against a stop (33) provided on the moveable element (26).

13. A horn actuator according to any preceding claim comprising a housing (13) within which said moveable element (26) is mounted for sliding movement in the manner of a piston.

14. A ihorn actuator according to claim 13 as dependant upon any one of claims 4 to 9, wherein said first spring (38) is arranged to act between part (27) of said moveable element (26) and part (19) of the housing (13), so as to bias them away from one another.

15. A safety arrangement for a motor vehicle comprising a horn actuator (11) according to any preceding claim provided in combination with an airbag module, the airbag module comprising a housing (2) configured to be mounted to a steering wheel, wherein the horn actuator (11) is arranged to releasably mount a cover (3) to the housing (2) for movement relative to the housing (2), the arrangement being such that removal of the cover (3) from the housing (2), or attachment of the cover to the housing (2), is prevented unless the moveable element (26) is moved to its release position by pressing the airbag cover (3) towards the housing (2).

16. A safety arrangement according to claim 15 as dependant upon claim 13 or 14, wherein the actuator housing (13) is formed as an integral part of the module housing (2).

17. A safety arrangement according to claim 16, wherein the actuator housing (13) and the module housing (2) are moulded from plastics material as a single unit.

18. A safety arrangement according to claim 15 as dependant upon claim 13 or 14, wherein said actuator housing (13) is formed separately from the module housing (2), but wherein the actuator housing (13) is secured to the module housing (2).

19. A horn-actuator substantially as hereinbefore described with reference to and as show in the accompanying drawings.

20. A safety arrangement for a motor vehicle comprising a horn- actuator substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

21. Any novel feature or combination of features disclosed herein.