GB2113756A - Preventing vehicle theft - Google Patents

Abstract

An engine driven vehicle is fitted with an anti-theft device which, when activated, serves to both disable an accessory, operation of which is necessary for normal driving of the vehicle, and also to prevent the opening of a lid which gives access to the disabled accessory. The lid may be the vehicle bonnet.

Description

SPECIFICATION Vehicle anti-theft device This invention relates to vehicle anti-theft devices. It is well known to fit a motor vehicle with an anti-theft device intended to prevent the vehicle's engine from being started by an unauthorised person. The known anti-theft devices usually serve to disable engine ancilliary equipment located in an engine compartment of the vehicle. In the case of a vehicle having a spark ignition engine using an ignition coil, then the antitheft device may serve for example to isolate the primary low voltage electric circuit of the coil.

A disadvantage of some of the known anti-theft devices is that they can be circumvented by opening the lid (bonnet) of the engine compartment, and by then restoring operation of the disabled engine ancilliary equipment. For example, if the primary circuit of the ignition coil has been isolated, then operation of the coil can be restored by connecting the coil direct to the vehicle battery by separate electrical leads.

An object of the invention is to provide a motor vehicle anti-theft device which is relatively difficult to circumvent, and accordingly the invention provides an engine driven vehicle fitted with an anti-theft device which, when activated, serves to both disable an accessory operation of which is necessary for normal driving of the vehicle, and also to prevent the opening of a lid which gives access to the disabled accessory. Thus, in order to steal a vehicle according to the invention, a thief would need to break open a locked lid before attempting to restore operation of a disabled vehicle accessory.

In putting the invention into practice, it is anticipated that the accessory to be disabled would normally be ancilliary equipment of the vehicle engine, for example engine ignition equipment, fuel injection equipment, or a petrol pump. However, as an alternative it would be possible to disable other equipment, such as steering or gear selecting equipment necessary for normal vehicle operation.

It is further anticipated that the disabled accessory will normally be located in the vehicle engine compartment and that the lid which is prevented from opening will be the lid (bonnet) of the engine compartment. However, the disabled accessory could be located elsewhere. For example, the disabled accessory could be an electric fuel pump located in a luggage compartment of the vehicle.

The anti-theft device could prevent the lid from being opened by disabling a lid release mechanism which normally serves for release of the lid. Alternatively there could be a lid latch forming part of the anti-theft device and separate from any such normal lid release mechanism.

The ancilliary engine equipment to be disabled may comprise the ignition coil primary electrical circuit.

The anti-theft device may include a control unit located in a passenger compartment of the vehicle and serving for the activation and deactivation of the lid-locking and accessory-disabling functions.

A vehicle anti-theft device according to the invention will now be described by way of example and with reference to the accompanying drawing which is a schematic layout showing operation of the device.

The device shown in the drawing is designed for use in a vehicle powered by a spark ignition engine. A control unit 1 will be installed inside a passenger compartment of the vehicle. It is preferred to mount the control unit behind the vehicle dashboard in such a way that wires leading to and from the unit are not readily accessible. The unit 1 serves to control operation of two solenoids disposed in an engine compartment of the vehicle.

Solenoid 2 serves to actuate a latch for locking the lid of the engine compartment, i.e. the bonnet, and such latch will be separate from and additional to a conventional bonnet latch which can be released by means of a conventional bonnet release mechanism. The other solenoid 3 together with a switch 4 forms a relay for energising the low voltage circuit of an ignition coil 5 connected to the vehicle by battery 6. Power is fed to the control unit 1 direct from the battery 6 and the unit 1 also receives inputs from an ignition switch 7, an emergency power input device 8, and a coded input device 9.

The control unit 1 contains timing and logic circuits (not shown), and operation of these circuits and of the anti-theft device will now be described.

When the vehicle has been left with the antitheft device activated, then the ignition switch 7 will be in an "off" position, the bonnet latch operated by the solenoid 2 will be in an operative position locking the bonnet, the switch 4 operated by the solenoid 3 will be open as shown in the drawing to isolate the coil 5, and the conventional bonnet lock (not shown) will of course be in a locking position. The solenoid 2 can be spring biased into its bonnet latching position and the coil switch 4 can be spring biased to an open circuit position, or alternatively one or both solenoids can be "double throw" solenoids which require to be energised to move them from whichever position they happen to be in.

In order to de-activate the anti-theft device and start the car engine, the driver of the car, having entered the vehicle, will first use his ignition key to turn the ignition switch 7 from its "off" position to a "run" position. The control unit 1 will receive an appropriate input from the ignition switch 7. The driver will then enter a code into the coded input device 9. The device 9 may comprise a keyboard having, for example, ten code keys which the driver can press and the code may require four of the buttons to be pressed in the correct sequence.

Circuitry within the control unit 1 will read the code entered on the keyboard, and assuming that the code is verified as being correct, then the control unit will give the appropriate command signals to the two solenoids 2 and 3 to cause the switch 4 to close to energise the coil and to cause the bonnet latch controlled by the solenoid 2 to be released. The car engine can then be started in conventional manner, for example by turning the ignition key to a "start" position. It will be understood that the vehicle bonnet will not automatically open as soon as the solenoid controlled bonnet latch is released, because the bonnet will still be held closed by the conventional bonnet latch mechanism.The purpose of the solenoid controlled bonnet latch is to prevent a would-be thief who has entered the passenger compartment from opening the bonnet by way of the normal bonnet release mechanism. Of course, a thief would need to open the bonnet in order to start the car engine because the switch 4 isolating the coil 5 is located beneath the bonnet in the engine compartment.

It is preferred to use a keyboard device as the means to provide "authorisation" input to the control unit 1, but instead one could use other means, for example a card reading device. This would, however, have the disadvantage that the driver could lose his card, or it could become damaged.

The control device is arranged to re-activate the anti-theft device automatically when the ignition switch 7 is switched off.

The control unit circuitry includes various logic and timing functions which provide safety facilities and convenience facilities as explained above.

In the event of the driver stalling the car engine (e.g. when pulling away from traffic lights) then the driver might turn the ignition key to an "off" position before attempting to restart the engine. In the absence of special provision for this occurrence, then the driver would have to punch out the code on the device 9 before being able to restart the engine, thus causing delay and embarrassment. For this reason, the control unit 1 will include a time delay function which will delay activation of the anti-theft device until a time of say one minute has elapsed from the time that the ignition switch is switched off.

In the event that the car owner might wish his car to be driven by another person (e.g. a parking valet) then, with the arrangement described above, it would be necessary for the owner to inform the other person as to the appropriate code. Further, with the described arrangement it would be impossible for a driver to prevent the anti-theft device from being activated whenever he removed the ignition key. This could be inconvenient if, for example, a driver wished to remove his ignition key merely to use his keys to open the luggage compartment of the car. These two problems can be avoided by providing means to inhibit normal automatic operation of the antitheft device upon removal of the ignition key.For example, two further input keys could be provided on the keyboard of the device 9, one key being an "inhibit automatic activation" key, and the other being a "return to automatic activation" key.

It will be appreciated that problems could arise if, after the car has been left with the anti-theft device activated, the vehicle battery located in the engine compartment should become flat. This problem is avoided by providing the emergency power input device 8. By plugging a power source into this device 8, emergency power can be provided to allow the anti-theft device to be deactivated so that the bonnet can be opened and the battery recharged.

The central control unit will sense the state of all components, and will include circuitry to ensure that no unsafe or incorrect condition can occur.

For example, in the event of the device 9 requiring the insertion of a coded card for operation, then the control unit would prevent the switch 4 from opening to cause the engine to stall in the event that the card should be removed whilst the engine is running and whilst the ignition switch is still turned on.

In the embodiment described the switch 4 serves to disable the ignition coil primary electrical circuit by isolating the ignition coil. Instead, the circuit could be disabled by arranging the switch 4 to short circuit contact breaker points when the anti-theft device is activated.

Claims (22)

1. An engine driven vehicle fitted with an antitheft device which, when activated, serves to both disable an accessory, operation of which is necessary for normal driving of the vehicle, and also to prevent the opening of a lid which gives access to the disabled accessory.

2. A vehicle according to Claim 1, in which the accessory to be disabled comprises ancilliary equipment of the vehicle engine.

3. A vehicle according to Claim 2, in which the engine ancilliary equipment to be disabled is part of the engine fuel supply equipment, for example a petrol pump or a fuel injector.

4. A vehicle according to Claim 2, in which the engine ancilliary equipment to be disabled comprises part of an ignition spark generating system of the engine, for example an ignition coil primary electrical circuit.

5. A vehicle according to any preceding claim, in which the accessory to be disabled is located in an engine compartment of the vehicle, and in which the lid which is prevented from being opened by the anti-theft device when activated is the lid of the engine compartment.

6. A vehicle according to Claim 5, in which the anti-theft device prevents the lid from being opened by means of a lid latch which is separate from, and provided in addition to, another engine compartment locking and release mechanism.

7. A vehicle according to Claim 6, in which the latch of the anti-theft device is solenoid operated.

8. A vehicle according to Claim 7, in which the solenoid is a "double throw" solenoid which must be electrically operated to move from whichever position it happens to occupy.

9. A vehicle according to Claim 7, in which the solenoid must be energised to release the lid latch from a latching position to which it is spring biased.

10. A vehicle according to Claim 6, in which the anti-theft device when activated prevents the lid from being opened by disabling a mechanism providing for releasing the lid.

1 1. A vehicle according to Claim 3, in which the engine ancilliary equipment to be disabled comprises an electrically operated fuel pump located in a luggage compartment of the vehicle.

12. A vehicle according to any preceding claim, in which a solenoid is provided for disabling the accessory to be disabled.

13. A vehicle according to any preceding claim, in which the anti-theft device includes a control unit located in a passenger compartment of the vehicle and serving to activate and de-activate the accessory disabling and lid opening prevention functions of the device.

14. A vehicle according to Claim 13, in which the control unit is so mounted that wires leading to and from the unit are not readily accessible.

1 5. A vehicle according to any preceding claim, in which the anti-theft system is arranged to be activated automatically in response to a particular occurrence.

1 6. A vehicle according to Claim 15, in which the anti-theft system is arranged to be activated automatically in response to the switching off of the vehicle engine by the turning of an ignition key.

1 7. A vehicle according to Claim 1 5 or Claim 16, in which means are provided selectively to inhibit said automatic operation of the anti-theft device.

18. A vehicle according to any one of Claims 15 to 17, and including a time delay mechanism to delay the activation of the anti-theft device until a predetermined time period has elapsed since the said particular occurrence.

1 9. A vehicle according to any one of Claims 13 to 18, in which de-activation of the anti-theft system requires the input of a code to the control unit.

20. A vehicle according to Claim 19, and including a keyboard having keys by means of which the code may be fed to the control unit.

21. A vehicle according to any one of Claims 13 to 20, and including an emergency power input by means of which electrical energy may be provided for de-activation of the anti-theft device in the event that the vehicle's battery should become flat.

22. An engine driven vehicle having an antitheft device substantially as described herein with reference to the accompanying drawing.