GB2281956A

GB2281956A - Vehicle steering wheel with airbag and pressure sensor switch

Info

Publication number: GB2281956A
Application number: GB9417441A
Authority: GB
Inventors: Gregor Zeller; Helmut Bonn
Original assignee: Petri AG
Current assignee: Petri AG
Priority date: 1993-08-30
Filing date: 1994-08-30
Publication date: 1995-03-22
Also published as: GB9417441D0; JPH07144645A; BR9403355A; FR2709461B1; DE4329120A1; FR2709461A1

Description

2281956 STEERING WHEEL FOR AUTOMOTIVE VEHICLES The present invention

relates to a steering wheel for an automotive vehicle and, in particular, to a steering wheel having an actuating switch, e.g. f or the horn, disposed on the steering wheel.

For safety reasons, it is desired to locate vehicle controls within easy reach of the driver. most preferably, it is desired to locate controls on the steering wheel, where the driver has direct access. In recent, known arrangements the (generally mechanical) push-button controls for actuating the signalling arrangement (e.g. horn) and other special functions are disposed in the steering wheel, more especially in the spokes thereof or above the steering wheel hub.

Problems arise with steering wheels having a shock-preventing airbag safety system (airbag), since the steering wheel dish serves to accommodate the airbag, with the result that the spokes and hub are largely covered. In consequence, when steering wheels which are provided with an airbag are used, the switch components are mounted either externally of the steering wheel or in the substructure of the airbag by means of retaining plates. However, when they are mounted externally of the steering wheel, the signals are undesirably actuated outside the direct access of the driver. By way of contrast, when they are mounted in the substructure of the airbag, the airbag needs to be detachably mounted so that, in order to actuate the signal switch, the entire airbag unit has to be moved. Furthermore, in view of the weight of the airbag unit, it is necessary to increase accordingly the response threshold for the signalling arrangement.

An object of the present invention is to provide a steering wheel of the described type having an actuating switch, which is easily mountable and actuatable.

According to the present invention there is provided a steering wheel for automotive vehicles having a shock-preventing airbag safety system (airbag) which is disposed in the steering wheel dish and includes a padded cover, and at least one actuating switch, which is also disposed in the steering wheel dish and is couplable through a relay to a signalling arrangement, wherein the actuating switch is formed by a pressure sensor which is located in a holder of the padded cover, or located in a cover of a signal generator incorporated in the steering wheel dish.

Described herein is a steering wheel with an airbag, wherein the signalling arrangement is actuated in a simple manner, by means of switches which are directly accessible to the driver. The airbag unit does not need to be moved, with the result that it can be fixedly installed. The sensors are only lightweight and can easily be securely ins erted into the airbag cover, so that there is no risk of any component parts, which might cause injury to the vehicle occupants, becoming detached in the event of the airbag being operatively deployed. An additional advantage of the steering wheel according to the invention also resides in the fact that, because of the increased surface of the airbag cover, a greater number of sensors can be incorporated, i.e. additional functions can possibly be moved from the instrument panel to the steering wheel -and can thus be made more easily accessible to the driver.

Where a plurality of sensors are provided, each may be marked by a visible symbol on the surface of the airbag cover and may have variably stepped resistance values for actuating different functions.

Preferably, the resistance of the or each pressure sensor changes as a result of the internal pressure of a polyurethane or similar foam, which internal pressure may be electronically regulated.

Further details of the present invention are explained hereinafter with reference to the accompanying drawings, in which:

Fig - 1 is a cross-sectional view through a shockpreventing airbag safety system; Fig. 2 is a plan view of the airbag unit illustrated in Fig. 1, including a partially exploded view of the cover; Fig. 3 is a perspective view of a steering wheel provided with a pressure sensor; and Fig. 4 is a block circuit diagram of the pressure sensor circuit.

The drawings illustrate an airbag unit having an airbag 1, a gas generator 2 and a padded cover 5. The unit is generally mounted in the dish of a steering wheel by mounting means which are not shown.

The airbag unit is provided with an actuating switch for actuating a signalling arrangement or other function. In the embodiment of Figs. 1 and 2, such switch is formed by a pressure sensor 6, which is adhered to the holder 4 of the padded cover 5 and moulded therein. The terminals of the sensor are combined in a central plug 7, which is used for the connection with an amplifier (not shown).

Fig. 3 of the drawings illustrates a steering wheel 8 having a signal generator 9, which is incorporated laterally into the dish and is provided with pressure sensor 10 disposed in the cover.

Fig. 4 of the drawings is a block circuit diagram of the sensor control, shown as two embodiments, so that the pressure sensor 6 is either connected to the relay 12 preceding the signal generator 11 through the intermediary of an electronic control means disposed in the steering wheel dish or the shock-preventing airbag safety system (outlined by dotted lines) or connected to the signal generator 11 through the intermediary of a central control means comprising the electronic amplifier arrangement and the relay (outlined by dash-dot lines).

Claims

1. A steering wheel for automotive vehicles having a shock-preventing airbag saf ety system (airbag) which is disposed in the steering wheel dish and includes a padded cover, and at least one actuating switch, which is also disposed in the steering wheel dish and is couplable through a relay to a signalling arrangement, wherein the actuating switch is formed by a pressure sensor which is located in a holder of the padded cover, or located in a cover of a signal generator incorporated in the steering wheel dish.

2. A steering wheel as claimed in claim 1, wherein the pressure sensor is adhered to and/or moulded in the holder, or respectively the cover of the signal generator.

3. A steering wheel as claimed in claim 1 or claim 2, wherein the pressure sensor is coupled to the relay through the intermediary of an amplifier.

4. A steering wheel as claimed in claim 3, wherein the pressure sensor is coupled to the relay through the intermediary of a central control means.

1

5. A steering wheel as claimed in claim 3, wherein the pressure sensor is coupled to the relay through the intermediary of an electronic control means disposed in the steering wheel dish or in the shock-preventing airbag safety system.

6. A steering wheel as claimed in any one of claims 1 to 5, wherein a plurality of pressure sensors, which are marked by visible symbols on the surface of the airbag cover and have variably stepped resistance values for actuating different functions, are provided in the airbag cover.

7. A steering wheel as claimed in any one of claims 3 to 6, wherein electrical terminals from the or each actuating switch are combined in a central plug which is used for the connection with the amplifier.

8. A steering wheel as claimed in any one of claims 2 to 7, wherein the resistance of the moulded-in sensor changes as a result of the internal pressure of the polyurethane foam and is regulated by electronics.

9. A steering wheel, substantially as hereinbef ore described with reference to the accompanying drawings.