GB2280772A

GB2280772A - Vehicle air-bag arrangement.

Info

Publication number: GB2280772A
Application number: GB9316104A
Authority: GB
Inventors: Denis Bourcart
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1993-08-03
Filing date: 1993-08-03
Publication date: 1995-02-08
Anticipated expiration: 2013-08-03
Also published as: GB2280772B; GB9316104D0

Abstract

An air-bag arrangement is intended to be mounted within the hub of a steering wheel. The arrangement comprises a battery 1 which is associated with an electric current generator which may comprise solar panel 3 and a battery charging control to ensure that the battery is always fully charged. The battery is connected through an operation detector 8, 9 to a crash sensor 5 and an electrically triggered air-bag 13. The operation detector detects operation of the motor vehicle, for example, by detecting rotation of the steering wheel and only passes power to the crash sensor and air-bag when the vehicle is operational. <IMAGE>

Description

DESCRIPTION OF INVENTION "INPROVEMENTS IN OR RELATING TO AN AIR-BAG ARRANGEMENT" THE PRESENT INVENTION relates to an air-bag arrangement and more particularly relates to an air-bag arrangement mounted in the hub of the steering wheel of a motor vehicle.

It has been proposed to provide an air-bag mounted within the hub of a steering wheel or a motor vehicle, the air-bag being adapted to be inflated in the event that an accident should arise, to provide protection for the driver of the vehicle.

Such an air-bag may be inflated by a pyrotechnic charge, that pyrotechnic charge being ignited by an electric squib.

Whilst power may be supplied to the electric squib through slip rings provided in the steering column, the provision of such slip rings is expensive, and, after several years of use, the slip rings may not operate properly. It is important, of course, that an air-bag arrangement should be ready for use instantly should an accident occur, at any stage during the operative life of the vehicle. Thus, for example, an air-bag arrangement may remain in place within the hub of a steering wheel for twenty years or more, but should operate in the intended manner should an accident arise at any time during that period.

Various proposals have been made to provide a totally self-contained air-bag arrangement mounted within the hub of a steering wheel, without any connections to the rest of the motor vehicle. However, all prior proposals suffer from one or more drawbacks.

The present invention seeks to provide an improved air-bag arrangement.

According to this invention there is provided an air-bag arrangement adapted to be mounted within a steering wheel of a motor vehicle, the air-bag arrangement comprising a battery, an electrical current generator connected to maintain the charge of the battery, the arrangement further comprising a crash sensor and means to pass electric power from the battery to the air-bag in response to a crash being sensed by the crash sensor.

Preferably the electrical current generator comprises a solar panel, the solar panel being positioned to receive light when a motor vehicle in which the arrangement is fitted is parked or used out-of-doors in daylight conditions.

Alternatively the electrical current generator comprises an electro-mechanical generator.

Preferably means are provided to pass power from the battery to the crash sensor and air-bag in response to operation of the vehicle.

Conveniently the means to pass power in response to operation of the vehicle comprise means adapted to close a switch in response to a predetermined movement.

In one embodiment the switch is a trembler switch adapted to be closed in response to vibration.

Alternatively the switch is adapted to be closed in response to rotation of the steering wheel.

Preferably the switch comprise a switch adapted to be closed when the switch has moved past a magnet which is fixed in position relative to the steering column of the vehicle.

Alternatively again the switch comprises a switch adapted to be closed by an ultra-sonic or infra-red detector.

Conveniently the switch is adapted to charge a capacitance with power from the battery, the crash sensor being operable to complete a circuit incorporating the capacitance and an electric squib within the air-bag and gas generator to cause inflation of the air-bag.

Preferably the crash sensor is adapted to close two switches in series with the squib.

Conveniently the arrangement may incorporate a diagnostic circuit adapted to provide a warning if a fault is present in the arrangement.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which FIGURE 1 is a block diagram of one example of an arrangement in accordance with the invention, and FIGURE 2 is a more detailed diagram of an arrangement in accordance with the invention.

Referring initially to Figure 1 of the drawings, an air-bag arrangement in accordance with the invention is intended to be totally self-contained within the hub of a steering wheel, with no operative connections to the rest of the vehicle.

The air-bag arrangement of Figure 1 may be contained totally within a recess formed beneath the central part of the steering wheel.

The arrangement comprises a battery 1, which is a light-weight battery of a re-chargeable type. The battery is associated with a battery charging control circuit 2 of any conventional design, to which is connected an electrical current generator 3, which may take the form of a solar panel, in which case the solar panel 3 is mounted on the exterior of the steering wheel so as to receive light whenever the vehicle is in daylight.

It is to be appreciated, therefore, that whenever the vehicle is parked or used out-of-doors, during daylight hours, light will fall on to the solar panel, and the battery charging control circuit will cause the battery to trickle charge. Thus, at all times, the battery will be substantially fully charged.

The battery 1 is connected to the remaining components of the air-bag arrangement through an operation detector 4. The function of the operation detector is to detect whenever the motor vehicle in which the air-bag is mounted is in use, and only to connect the battery to the remaining components of the air-bag arrangement, when the vehicle is in use. The operation detector may take many forms, but typically may comprise an element which is responsive to movement, that movement being generated when the vehicle is in use. The movement may comprise vibration, such as vibration from the engine of the vehicle, or due to movement of the vehicle, or may comprise rotational movement of the steering wheel.

Thus, it is envisaged that the arrangement mounted within the hub of a steering wheel of the motor vehicle may include a trembler switch or some other vibration responsive switch, or may include a reed switch which cooperates with one or more magnets which are mounted directly on the steering column assembly, so that as the steering wheel is rotated the reed switch will move past the magnets, the reed switch thus being closed.

Whilst the operation detector may be associated with a "timer" to ensure that power is supplied from the battery to the remaining components of the air-bag arrangement for a predetermined period of time after the last vibration or rotation of the steering wheel is sensed, in order to ensure that the air-bag arrangement remains fully operational when a car is being driven on a very smooth road in a straight line, it is envisaged that the operation detector may supply power from the battery to a capacitance, thus charging up the capacitance. It will be power from the capacitance that is utilised to trigger the air-bag should a crash arise. The capacitance thus acts as a timer or delay circuit, since once the capacitance has been charged it will remain charged for a considerable period of time.

It is to be appreciated, however, that various other types of arrangement may be utilised to sense operation of the motor vehicle. For example, an ultrasonic or infra-red detector may be provided adapted to respond to the presence of a person in the vehicle, and to close an appropriate switch.

The operation detector is connected to a crash sensor 5 which may be of any conventional form, the crash sensor being such that when a crash is sensed the appropriate electrical pulse is passed to an air-bag 6.

The pulse is passed through en electric squib within the gas generator of the air-bag, thus causing the air-bag to inflate.

Whilst a solar panel has been referred to as the electric current generator any convenient type of generator may be used. For example, an electromechanical generator may be provided comprising one or more coils mounted in the steering wheel, adapted to move, on rotation of the steering wheel, past one or more magnets that are fixed in position.

Figure 2 illustrates one particular example of an arrangement in accordance with the invention.

In this embodiment the electric current generator 3 may again comprise a solar panel connected through a diode 7 to charge the battery 1. A Zener diode 7' is connected from the output of the solar panel to earth, to avoid too high a current being passed through the battery. The diodes 7 and 7' thus provides the battery charging control function.

The battery 1 is connected to a switch 8 associated with a rotation sensor 9, and thus the switch 8 may comprise a reed switch, the rotation sensor being one or more magnets associated with the reed switch but which are fixed in position so that the switch is closed on rotation of the steering wheel in which the arrangement of Figure 2 is mounted.

The switch 8 is such that when it is closed, electrical charge from the battery 1 is supplied to a capacitance 10. Thus, when rotation is sensed the capacitance 10 becomes fully charged.

A crash sensor 5 is provided adapted, when a crash is sensed, to close two switches 11,12 which are connected in series with a squib 13 which is located within the gas generator of an air-bag. The crash sensor 5 may comprise two sensor elements, each controlling a respective one of the switches 11,12. When the switches 11 and 12 are closed by the crash sensor the capacitance 10 will discharge through the squib 13, thus activating the air-bag. A diagnostic or monitoring circuit 14 may be provided. The circuit may be adapted to illuminate a warning light 15 should a fault arise.

It is to be appreciated that whilst the invention has been described with reference to preferred embodiments, many alternative embodiments may be devised within the scope of the invention.

Claims

CLAIMS:

1. An air-bag arrangement adapted to be mounted within a steering wheel of a motor vehicle, the air-bag arrangement comprising a battery, an electrical current generator connected to maintain the charge of the battery, the arrangement further comprising a crash sensor and means to pass electric power from the battery to the air-bag in response to a crash being sensed by the crash sensor.

2. An arrangement according to Claim 1 wherein the electrical current generator comprises a solar panel, the solar panel being positioned to receive light when a motor vehicle in which the arrangement is fitted is parked or used out-of-doors in daylight conditions.

3. An arrangement according to Claim 1 wherein the electrical current generator comprises an electromechanical generator.

4. An arrangement according to any one of the preceding Claims wherein means are provided to pass power from the battery to the crash sensor and air-bag in response to operation of the vehicle.

5. An arrangement according to Claim 4 wherein the means to pass power in response to operation of the vehicle comprise means adapted to close a switch in response to a predetermined movement.

6. An arrangement according to Claim 5 wherein the switch is a trembler switch adapted to be closed in response to vibration.

7. An arrangement according to Claim 5 wherein the switch is adapted to be closed in response to rotation of the steering wheel.

8. An arrangement according to Claim 5 wherein the switch comprises a switch adapted to be closed when the switch has moved past a magnet which is fixed in position relative to the steering column of the vehicle.

9. An arrangement according to Claim 5 wherein the switch comprises a switch adapted to be closed by an ultra-sonic or infra-red detector.

10. An arrangement according to any one of Claims 4 to 9 wherein the switch is adapted to charge a capacitance with power from the battery, the crash sensor being operable to complete a circuit incorporating the capacitance and an electric squib within the air-bag and gas generator to cause inflation of the air-bag.

11. An arrangement according to Claim 10 wherein the crash sensor is adapted to close two switches in series with the squib.

12. An arrangement according to any one of the preceding Claims incorporating a diagnostic circuit adapted to provide a warning if a fault is present in the arrangement.

13. An air-bag arrangement substantially as herein described with reference to and as shown in Figure 1 of the accompanying drawings.

14. An air-bag arrangement substantially as herein described with reference to and as shown in Figure 2 of the accompanying drawings.

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