WO2011038828A1

WO2011038828A1 - Horn activation device and safety arrangement having a horn activation device

Info

Publication number: WO2011038828A1
Application number: PCT/EP2010/005551
Authority: WO
Inventors: Remi Baillivet; Jean-Francois Prat
Original assignee: Autoliv Development Ab
Priority date: 2009-09-29
Filing date: 2010-09-09
Publication date: 2011-04-07
Also published as: DE102009043372B4; DE102009043372A1

Abstract

The invention relates to a horn activation device (10) for use in a steering wheel of a motor vehicle having a cover (3), having two horn contacts (5, 6) and a moveable element (4) which can be moved between an initial position and an activation position when pressure is applied to the cover (3), wherein the moveable element (4) is prestressed in the direction of the initial position, and the horn contacts (5, 6) are electrically disconnected from one another in the initial position and are in electrical contact with one another in the activation position in order to trigger an acoustic horn signal, characterized in that a sliding contact face (58) is formed on a first horn contact (5), and in that a contact element (8) is arranged on the moveable element (4), which contact element (8) slides along the sliding contact face (58) between the initial position and the activation position during the displacement of the moveable element (4), and in doing so said contact element (8) connects the horn contacts (5, 6) electrically to one another.

Description

Horn activation device and safety arrangement having a horn activation device

The invention relates to a horn activation device for connecting to a steering wheel of a motor vehicle having a cover, having two horn contacts and a movable element which can be moved between an initial position and an activation position when pressure is applied to the cover, wherein the moveable element is prestressed in the direction of the initial position, and the horn contacts are electrically disconnected from one another in the initial position and are in electrical contact with one another in the activation position in order to trigger an acoustic horn signal. The invention also relates to a safety device having such a horn activation device.

Modern motor vehicles are equipped with a large number of safety devices, for example air bags, which can be arranged at various locations within a motor vehicle. In order to provide protection in the event of a frontal impact, an airbag module is arranged on the steering wheel, in particular in the steering wheel head, said airbag module comprising a gas generator and an air bag which expands and is filled by the gas generator with deployment gas if appropriate sensor data are present. The airbag module is generally arranged in a housing which is covered by a covering in the direction of the driver. The covering has predetermined tearing lines or predetermined tearing points such that, after the gas generator has been triggered, the airbag can pass through the covering and be deployed. The covering serves firstly to provide an attractive visual appearance and secondly to protect against contaminants or changes to the installation situation of the airbag module. In order to trigger a horn signal, horn switches or horn activation devices are arranged within the steering wheel. These horn switches or horn activation devices are generally coupled to the covering and can be pressed in the direction of the steering wheel hub counter to a spring force in order to electrically connect the horn contacts to each other so as to trigger a horn signal. WO 2006/076897 A1 discloses a generator carrier for a driver airbag module for installation in a steering wheel of a motor vehicle, in which two horn contacts which can be placed in electrical contact with one another are arranged on a generator carrier. One of the horn contacts is provided to be electrically earthed in the installation state of the generator carrier, in which case an attachment region of the generator carrier is designed to fasten a gas generator and is positioned in relation to the earthed horn contact in such a way that when the gas generator is correctly fastened in the fastening region, electrical contact is produced between the earthed horn contact and the gas generator. Deformation of the horn contacts when pressure is applied causes the two horn contacts to be electrically connected to one another, with the result that a horn signal is triggered.

WO 2007/145549 A1 describes a safety arrangement having an airbag and a covering on which a moveably mounted, cylindrical element is arranged. When the cover is pressed downward, said moveably mounted, cylindrical element is placed in contact with a horn contact which is embodied as a resilient clip. The resilient clip is mounted on a support plate to which a second horn contact is likewise fastened. In the initial state, the electrical contacts are spaced apart from each other. If the cover is pressed downward, the moveable element comes into contact with the resilient clip and presses the latter downward in the direction of the second horn contact. As soon as the two contacts touch each other, the current circuit is closed and the horn signal is triggered. The object of the present invention is to make available a horn activation device with which reliable contact formation and activation of the horn can be ensured even when the horn is not used for a relatively long time.

This object is achieved according to the invention by means of a horn activation device having the features of the main claim and a safety device having the features of claim 1 1. Advantageous refinements and developments are disclosed in the subclaims.

The horn activation device according to the invention for use in a steering wheel of a motor vehicle having a cover, two horn contacts and a movable element which can be moved between an initial position and an activation position when pressure is applied to the cover, wherein the moveable element is prestressed in the direction of the initial position, and the horn contacts are electrically disconnected from one another in the initial position and are in electrical contact with one another in the activation position in order to trigger an acoustic horn signal, provides that a sliding contact face is formed on a first horn contact, and that a contact element is arranged on the moveable element, which contact element slides along the sliding contact face between the initial position and the activation position during the displacement of the moveable element, and in doing so said contact element connects the horn contacts electrically to one another. Since the contact element slides along a contact face of a horn contact when the cover is pressed down, the relative movement between the horn contact and the contact element generates friction which removes possibly present corrosion on the contact faces, ensuring that the layers of corrosion which are possibly present and which could impede the formation of electrical contact are effectively removed even after the horn has not been activated for a long time. In this way, the horn contacts are reliably connected to one another, with the result that the intermediately positioned contact element makes available a sliding contact which keeps the contact faces clean, or cleans them, as a result of the fact that the contact faces rub against one another and grind on one another. The contact element is preferably continuously connected to a horn contact in this context so that uninterrupted electrical contact can be formed at this horn contact and electrical signals can be reliably passed on.

The movable element is preferably mounted in a longitudinally displaceable fashion in order to pass on the pressing movement directly to the cover. It is basically also possible for the moveable element to be rotationally mounted, which requires the longitudinal movement of the cover to be converted into a rotational movement. This may be done, for example, by means of levers, a sliding-block guide or a movement thread.

Prestress is preferably applied to the contact element in the direction of the sliding contact face of the first horn contact, with the result that a certain contact pressure of contact element is always present on the sliding contact face. The prestress can be applied by means of a spring element which causes the contact element to be moved in the direction of the sliding contact face. The contact element itself can be embodied as a spring even if other devices for exerting a prestressing force and pressing the contact element against the sliding contact face can be provided. For example, the sliding contact face can be mounted in a mobile and elastic fashion in the direction of the contact element, with the result that both the contact element and the sliding contact face are pressed against one another in the activation position.

Furthermore, it is possible to provide that the moveable element is prestressed in the direction of the initial state by means of at least one spring, with the result that the cover is held in the initial position. As a result, firstly a certain force has to be applied so that the sliding contact face can be placed in contact with the contact element. This ensures that the horn is only activated intentionally since a minimum force has to be applied to the cover in order to displace the moveable element out of the initial position and into the activation position.

One development of the invention provides that the contact element is connected to the second horn contact by means of an electrically conductive spring, so that by means of this spring, which can at the same time also prestress the moveable element in the direction of the initial position, a continuous electrically conductive connection is implemented between the contact element and the second horn contact. The formation of contact by means of an electrically conductive spring also ensures that corrosion does not occur due to very small relative movements between the spring and the contact element on the one side and the second horn contact on the other. The mounting of the horn activation device is made easier by the electrically conductive springs since there is no need to produce a permanent connection between the contact element and the second horn contact by means of a plug- type connection or a soldered connection. The spring can also mechanically secure the contact element to the mechanical element, for example in that in one embodiment of the spring as a helical spring a radial projection is formed on the moveable element, which protects the spring against slipping down the moveable element.

One development of the invention provides that the moveable element has a mechanical stop which blocks a displacement in the activation direction, with the result that the mechanical blocking of the displacement of the movable element, and therefore also of the cover, does not have to take place by means of the electrical contact. The stop of the movable element is preferably arranged in such a way that the displacement of the moveable element, and therefore also of the cover, is not blocked until after the contact element has entered into contact with the horn contact and has travelled for a certain distance on the sliding contact face. This makes it possible to set the length of the sliding contact distance. The mechanical stop then enters into engagement with a corresponding device, either on the module carrier or on the steering wheel only after a certain displacement travel has occurred, and said mechanical stop blocks further movement of the cover and the moveable element when the pressure is being applied to the cover. The contact element can be embodied as a spring clip.

The safety device having a horn device which has been described above provides that an airbag module is arranged in a housing in a steering wheel, with the horn activation device being detachably fastened to a cover of the housing, and the cover being displaceable relative to the housing in order to activate the horn.

An exemplary embodiment of the invention will be explained in more detail below with reference to the appended figures, in which:

Figure 1 shows a schematic sectional illustration of part of a horn activation device in the initial position; Figure 2 shows a horn activation device according to Figure 1 in an activation position;

Figure 3 shows a horn activation device according to Figure 2 in an end stop;

Figure 4 is a view of a detail of a moveable element with a contact element;

Figure 5 is an exploded drawing of the moveable element with built-on components;

Figure 6 shows a view of a detail of the moveable element and of the contact element; and Figure 7 is an enlarged sectional illustration of a detail of a variant according to Figure 4.

Figure 1 is a sectional illustration of a horn activation device 10 which is arranged on a module carrier 1 to which a plurality of components of a steering wheel can be fastened, for example an airbag module 2 which is shown schematically in a partial illustration. The module carrier 1 is connected to the rest of the steering wheel which has a receptacle for fastening to a steering column or the like and generally has an annular gripping rim. The driver's airbag is generally arranged as part of the airbag module in the centre of the steering wheel. The airbag module 2 and the module carrier 1 are covered by means of a cover 3 in the direction of the driver, which cover 3 protects and conceals the technical devices within the steering wheel. The cover 3 can be moved in the direction of the module carrier 1 in order to activate a horn (not illustrated). After a certain activation travel has been passed through, the horn is activated, and after the cover 3 is released it is moved back again and the horn signal is interrupted. A projection 13 is arranged on the module carrier 1 , which projection 13 engages in a recess inside the module carrier 3 so that the cover 3 cannot be readily disconnected from the module carrier 1 , with the result that the cover 3 is held on the module carrier 1

The cover 3 is coupled by means of a pin or the like to a moveable element 4 which is of elongate design. The moveable element 4 moves when a compressive force is applied to the cover 3 counter to a spring force which is applied by means of a spring 7, in the direction of the module carrier 1 , in the downward orientation illustrated in Figure 1 . Two electrical horn contacts 5, 6 are arranged on the module carrier 1. The first horn contact 5 extends essentially parallel to the direction of displacement of the moveable element 4, while the second horn contact 6 is arranged on a base, oriented perpendicular to the direction of displacement, of a guide of the end region of the moveable element 4. The second electric horn contact 6 is connected in an electrically conductive fashion to a contact element 8 via the electrically conductive helical spring 7 which is embodied as a compression spring. The contact element 8 is embodied as a spring clip which is arranged and secured at the upper end to a bearing shoulder of the moveable element 4. The contact element 8 extends, in the form of the spring clip, essentially parallel to the longitudinal extent of the moveable element 4 and parallel to the direction of displacement of the moveable element 4.

An insertion slope 17, which is oriented in the direction of the first horn contact 5, is formed on the module carrier 1 , with the result that when the moveable element 4 is inserted during the mounting process both that end of the moveable element 4 which faces away from the cover 3, as well as the spring 7 and the contact element 8 are moved away in the direction of the first horn contact 5. As a result, that end of the moveable element 4 which faces away from the cover 3 can be easily and securely introduced into the guide which is formed in the base on which the spring 7 rests. The contact element 8, which is embodied such that it is sprung in the outward direction, is moved under prestress in the direction of a bearing face by the insertion slope 17, which bearing face terminates essentially flush with the first horn contact 5 so that when the cover 3 is pressed down the contact element 8 is pressed against the first horn contact 5. Furthermore, a mechanical stop 41 , to which a stop 1 1 , corresponding to the latter, on the module carrier 1 is assigned is provided on the moveable element 4 and lies opposite said corresponding stop 1 1 . After the maximum provided displacement travel of the moveable element 4 has been achieved, the stops 41 , 1 1 enter into contact with one another and block further downward displacement. Instead of a stop 41 with a contact face protruding substantially perpendicular to the longitudinal direction of the moveable element 4 it is also possible that the lower end of the moveable element 4 forms the end stop for the movement of the moveable element 4. The protrusion formed at the upper circumference may have at it underside a bevel, designed as a lead-in chamfer, which facilitates the introducing into the module carrier 1. The moveable element 4 is held in its position by the resilient lug at which the protrusion with the stop 41 is formed. In the position illustrated in figure 1 , the electrically conductive spring 7 presses, via the moveable element 4, the cover 3 upward in the direction of the driver. The displacement movement is limited by the stop 13 on the module carrier 1 . The spring 7 holds the cover under prestress with respect to the module carrier 1 and presses the moveable element 4 against the cover 3. In the position illustrated in Figure 1 , the horn contacts 5, 6 are disconnected electrically from one another since an electrical connection is not made available between the second horn contact 6, the electrically conductive spring 7 and the contact element 8 with the first horn contact 5. Figure 2 shows the position of the horn activation device 10 in which the horn signal is just being triggered. The lower end, facing away from the cover 3, of the contact element 8 is just entering into connection with the sliding contact face 58 of the first contact 5 and is therefore bringing about electrical contact with the horn contact 6 by means of the first horn contact 5, the contact element 8 and the electrically conductive spring 7, with the result that the circuit in which the horn is located is closed and a horn signal is triggered. From Figure 2 it is apparent that there is a distance between the stops 41 , 1 1 , with the result that the cover 3 can be displaced further in the downward direction counter to the spring force 7 in the direction of the module carrier 1 . The end position of the horn activation device is illustrated in Figure 3. The two stops 41 , 1 1 bear against one another, thereby preventing a further downward movement of the cover 3 and therefore of the moveable element 4 and of the contact element 8. A free space, which corresponds to the entire displacement travel of the cover 3 and therefore also of the moveable element 4, is formed between the projection 13 and the cover 3. The lower end of the contact element 8 has slid along the sliding contact face 58 of the first horn contact 8 and in doing so has brought about the electrical connection between the two horn contacts 5, 6 over the entire displacement travel and the entire displacement period. Owing to the spring prestress of the contact element 8 which is embodied as a spring clip, the lower end of the contact element 8 has always been pressed in the direction of the sliding contact face 58. Owing to the friction which is produced in the process, deposits or corrosion components which were located on the first horn contact 5 or on the contact element 8 have been removed. This ensures that electrical contact is made.

Figure 4 is an illustration of a detail of the moveable element 4. At the upper end, a total of three stops 41 in the form of projections are formed. These projections 41 limit the maximum displacement of the moveable element 4 within the module carrier 1 .

An electrically conductive, helical compression spring 7, which securely holds a bent contact element 8 against the moveable element 4, is arranged on the moveable element 4, around a slender pin. The contact element 8 has a tongue which extends essentially parallel to the longitudinal extent of the moveable element 4. A roof-like bent portion 85 is provided on the lower end of the tongue, which bent portion 85 extends outward, resulting in a linear contact face. An annular receptacle 84, which has a recess through which the stem of the moveable element 4 can be plugged, is provided at an angle to the tongue. The spring 7 presses the receptacle 84 against a shoulder and holds the contact element 8 securely against the moveable element 4. Figure 5 shows the individual components in an exploded illustration. The electrically conductive spring 7 is embodied as a helical compression spring. The anti-rotation elements in the form of punched-out elements can be seen within the recess in the contact element 8. Corresponding to this, projections are formed in the stem of the moveable element 4, which stem is preferably formed from plastic, and such projections engage in a positively locking fashion in the recesses within the receptacle 84, as a result ensuring the orientation of the contact element 8, in particular of the linear contact face 85, in relation to the moveable element 4. The moveable element 4 can be held in an unambiguous orientation with respect to the module carrier 1 by means of guide elements, for example the projections 41 , which are provided on the outside, in order to ensure that after the activation position has been reached the contact element 8 is placed in contact with the first electrical contact 5. Figure 6 shows an illustration of a detail in which it is apparent that the receptacle 84 is provided with positively locking devices in which ribs of the moveable element 4 engage, with the result that protection is provided against rotation about the longitudinal axis of the moveable element 4. Additional projections 48, whose function will be explained with reference to Figure 7, are provided on the ribs.

Figure 7 is a sectional illustration of part of the moveable element 4. The projections 48 serve to ensure that a number of windings of the spring 7 are compressed and held in the direction of the receptacle 84 of the contact element 8, with the result that the contact element 8 is pressed against a shoulder 40 on the underside of the projections 48. The projections 48 prevent the spring 7 from slipping downward. In the illustrated exemplary embodiment, two turns of the spring 7 are compressed in the direction of the shoulder 40 and therefore held under prestress on the contact element (8) which rests thereon.

Claims

Patent Claims

1. Horn activation device (10) for use in a steering wheel of a motor vehicle having a cover (3), having two horn contacts (5, 6) and a movable element (4) which can be moved between an initial position and an activation position when pressure is applied to the cover (3), wherein the moveable element (4) is prestressed in the direction of the initial position, and the horn contacts (5, 6) are electrically disconnected from one another in the initial position and are in electrical contact with one another in the activation position in order to trigger an acoustic horn signal, characterized in that a sliding contact face (58) is formed on a first horn contact (5), and in that a contact element (8) is arranged on the moveable element (4), which contact element (8) slides along the sliding contact face (58) between the initial position and the activation position during the displacement of the moveable element (4), and in doing so said contact element (8) connects the horn contacts (5, 6) electrically to one another.

2. Horn activation device according to Claim 1 , characterized in that the moveable element (4) is mounted in a longitudinally displaceable fashion.

3. Horn activation device according to Claim 1 or 2, characterized in that prestress is applied to the contact element (8) in the direction of the sliding contact face (58).

4. Horn activation device according to one of the preceding claims, characterized in that the moveable element (4) is prestressed in the direction of the initial position by means of at least one spring (7).

5. Horn activation device according to one of the preceding claims, characterized in that the contact element (8) is connected to the second horn contact (6) by means of an electrically conductive spring (7).

6. Horn activation device according to Claim 5, characterized in that at one end the spring (7) mechanically secures the contact element (8) to the moveable element (4).

7. Horn activation device according to Claim 5 or 6, characterized in that the spring (7) is embodied as a helical spring.

8. Horn activation device according to one of the preceding claims, characterized in that the moveable element (4) has a mechanical stop (41 ) which blocks displacement in the activation direction.

9. Horn activation device according to Claim 8, characterized in that the stop (41 ) of the moveable element (4) is arranged in such a way that the displacement is blocked after the contact element (8) has entered into contact with the horn contact (5).

10. Horn activation device according to one of the preceding claims, characterized in that the contact element (8) is embodied as a spring clip.

1 1 . Safety device having a horn activation device (10) according to one of the preceding claims, with an airbag module (2) which is arranged in a housing in a steering wheel, wherein the horn activation device (10) is detachably fastened to a cover (3) of the housing (1 ), and the cover (3) can be moved in relation to the housing (1 ) in order to activate the horn.