VEHICLE IMMOBILISATION SYSTEM

Abstract: A system for immobilising a stolen vehicle comprises a unit (10) for mounting in a vehicle and first and second remote control devices (11, 21). The vehicle unit (10) comprises a receiver (13) for receiving wireless control signals directly from the remote control devices (11, 21) and means (15) for immobilising the vehicle in response to predetermined control signals from either remote control device (11, 21). The first remote control device (11) is arranged to transmit a predetermined control signal which is substantially unique to the receiver (13) and the second remote control device (21) comprises means (16) for selecting the predetermined control signal to be transmitted. In use, the first remote control device (11) is kept by the vehicle's owner, so that the vehicle can be immobilised each time it is left unattended. The second remote control (21) device is kept by the police and in the event of a car theft, the police merely have to identify the vehicle, select an appropriate control signal and then transmit the control signal, either from a pursuit vehicle or from the roadside, to immobilise the vehicle.

Description: Vehicle Immobilisation System This invention relates to a vehicle immobilisation system. Car thefts and joy-ridings are commonplace nowadays. Typically, the most conventional way adopted by the police of stopping a stolen vehicles is either by pursuing it or by placing a device on the road, which punctures the vehicle's tyres . Both of the above-mentioned methods of stopping stolen vehicles are unsatisfactory, since they generally involve dangerous pursuits at high speeds. It has been proposed to overcome the above-mentioned problem by providing a device for remotely disabling a vehicles engine. One such device is disclosed in US 5,533,589, in which owners are able to disable their vehicles by dialling a unique telephone number followed by a security code. A disabling signal is then transmitted over the conventional cellular telephone network to a receiver in the vehicle's engine compartment . A disadvantage of the above-mentioned system is that it is complicated in construction, thereby making it expensive, particularly owing to the fact that the system incorporates a cellular telephone receiver. The added expense and limited use of the above- mentioned type of system means that car manufacturers and owners will be deterred from installing such a system in their vehicles . I have now devised a vehicle immobilisation system, which alleviates the above-mentioned problems. In accordance with this invention, there is provided a immobilisation system for a vehicle, the system comprising a vehicle unit and first and second remote control devices, the vehicle unit comprising a receiver for receiving wireless control signals directly from said remote control devices and means for immobilising said vehicle in response to predetermined control signals from either said remote control device, wherein said first remote control device is arranged to transmit a predetermined control signal which is substantially unique to said receiver and wherein said second remote control device comprises externally operable selection means for selecting the predetermined control signal to be transmitted. In use, the first remote control device is kept by the vehicle's owner, so that the vehicle can be immobilised each time it is left unattended. The second remote control device is kept by the police and in the event of a car theft or joyriding, the police merely have to identify the vehicle, select an appropriate control signal and then transmit the control signal, either from a pursuit vehicle or from the roadside, to immobilise the vehicle. It will be appreciated that the system is essentially a conventional vehicle immobilisation system with the added facility that it can be activated by the police. Thus, the cost of the system to a vehicle manufacturer or owners is no greater than the cost of a conventional vehicle immobilisation system, of the type commonly fitted to vehicles nowadays. In one embodiment, the second remote control device comprises means for determining the format of the predetermined control signal to be transmitted, from the vehicle's registration number, which is input using said externally operable selection means. In this embodiment, the second remote control device may comprise a database containing the registration numbers of vehicles and format of their corresponding control signal . Alternatively, the remote control device may be arranged to obtain the format from a remote database, say located at police headquarters . In an alternative embodiment, the second remote control device comprises means for determining the format of the predetermined control signal to be transmitted, from the make and/or model of the vehicle, which is input using said externally operable selection means. Most conventional vehicle immobilisation systems transmit a coded control signal, which changes each time the system is activated or deactivated, in order to prevent unauthorised persons from receiving the transmitted code and then using the transmitted signal to deactivate the vehicle's immobiliser . In order to overcome this problem, the vehicle unit may be responsive to either a master control signal from the second remote control device or a control signal transmitted by the first remote control device. Preferably, the vehicle unit will not respond to control signals from the second control unit, once the vehicle is immobilised using said first remote control device. Thus, in the event that anyone manages to fraudulently obtain the master control signal, they will not be able to de-activate the immobiliser and steal the vehicle. Preferably, the second remote control device comprises a directional aerial, so that the control signal can be directed at the vehicle to be immobilised, thereby avoiding any risk of immobilising other vehicles in the vicinity. Preferably, the power of the signal transmitted by the second remote control device is substantially greater than the power transmitted by the first remote control device. Thus, the vehicle can be immobilised by the police from a distance, which is much greater than those in which conventional remote devices normally operate. The high power of the control signal also means that the vehicle unit will receive a strong signal, even if the vehicle's bodywork has significantly attenuated the signal . Preferably the vehicle unit is arranged not to respond to control signals received from the first remote control device, once a control signal has been received from the second remote control device. Thus, joyriders and car thieves cannot override any signals which have been transmitter by the police to stop their vehicle. Preferably the vehicle unit can be arranged to only partially immobilise the vehicle, so that the vehicle slows rather than stops, thereby avoiding any risk of an accident being caused by the vehicle stopping suddenly. Preferably the vehicle unit comprises means for selecting and/or varying the degree of immobilisation, for example so that the vehicle can be brought to a stop in a controlled manner. Preferably the vehicle unit comprises means for deactivating the immobiliser. An embodiment of this invention will not be described by way of example only and with reference to the accompanying drawing, in which: FIGURE 1 is a block diagram of a vehicle immobilisation system in accordance with this invention; FIGURE 2 is a perspective view of a remote device of the system of Figure 1, for installing in a police vehicle; and FIGURE 3 is a perspective view of the system of Figure 1 being used to stop a vehicle. Referring to Figure 1 of the drawings, there is shown a vehicle immobilisation system comprising a unit 10 for mounting in a vehicle, and one or more remote devices e.g. 11 for normally operating the vehicle unit 10. The system may be fitted in a vehicle from new, alternatively it may be fitted to an existing vehicle as an accessory. The remote control device 11 comprises a transmitter which is connected to an aerial 21. The remote control device 11 transmits a coded control signal when an actuator thereon is actuated. The vehicle unit 10 is normally mounted under the bonnet of the vehicle and a small aerial 19 is provided for receiving wireless control signals from the remote control device 11. The aerial 19 is connected to a receiver 13, which receives and decodes any signals that are received. The decoded signal is then passed to a control circuit 14, which verifies that the received code corresponds with a predetermined code, which is substantially unique to the vehicle . If a valid code is received, the control circuit 14 changes that state of a device 15 which immobilises the vehicle, say by inhibiting the vehicle's ignition or engine management system. It will be appreciated that the system as hereinbefore described is the same as a conventional vehicle immobilisation system. However, in accordance with this invention, the vehicle unit 10 is also arranged to respond to control signals transmitted from a further remote control device 12 kept and operated by the police. Referring to Figure 2 of the drawings, the remote control 12 comprises a self-contained unit 21 for mounting in a police car. Alternatively, it may comprise a portable unit for use on the roadside. The unit 21 comprises a front panel having a plurality of alpha-numeric keys 16, which can be used to enter the identity of the vehicle to be stopped. The unit 20 is connected to a directional aerial, which can either be fixed to transmit signals in one direction or movable, so that signals can be transmitted in any direction. Referring again to Figure 1 of the drawings, the keys 16 on the front of the unit 21 are connected to a control circuit 17, which determines the code format of the signal that needs to be transmitted, in order to immobilise the identified vehicle . The control circuit 17 may comprise a database, which provides details of the required code format, once the registration number, make or model of the vehicle has been entered. Alternatively, the control circuit 17 may be arranged to obtain the details via a radio link from police headquarters. In a further embodiment, the code format of the signal to be transmitted can be input manually, once the operator has determined the correct format over the radio from police headquarters. The selected code format to be transmitted is fed to a transmitter circuit 18, which modulates the code onto a high frequency radio carrier wave. The output power of the transmitter circuit 18 is preferably much greater than the output power of the transmitter in the conventional remote control device 11. The high power radio signal is transmitted via the directional aerial 20 to the vehicle to be immobilised. The normal code that needs to be transmitted from the remote device 11 to immobilise and de-immobilise the vehicle is quite complex and often changes each time the vehicle is immobilised. Thus, the police unit 21 may transmit a master code, which is different from the normal code, the vehicle unit 10 being arranged to respond to either the normal code or the master code. This master code can be unique to the vehicle, to the make of vehicle or to the model of vehicle. In the latter two cases, the directional aerial 20 on the police unit helps to ensure that adjacent vehicles of the same make or model are not also immobilised when the police unit 20 is activated. Referring to Figure 3 of the drawings, once the identity of the stolen vehicle 30 has been entered into the unit 21 in the police vehicle 31, the stolen vehicle 30 can be immobilised by pursuing it in the police vehicle 31 and actuating a switch 22 (Figure 2) on the police unit 21 to cause a directional control signal S to be transmitted to the stolen vehicle 30. The power of the transmitted control signal S is sufficient to reach the unit 10 in the stolen vehicle 30 from a distance of 50 metres or more. When the unit 10 in the stolen vehicle receives the signal S from the unit 21 in the police vehicle 31, the stolen vehicle is partially immobilised, so that it gradually loses power, thereby enabling the driver to be apprehended safely, without any need for a prolonged high speed pursuit.

Claims: Claims 1) An immobilisation system for a vehicle, the system comprising a vehicle unit and first and second remote control devices, the vehicle unit comprising a receiver for receiving wireless control signals directly from said remote control devices and means for immobilising said vehicle in response to predetermined control signals from either said remote control device, wherein said first remote control device is arranged to transmit a predetermined control signal which is substantially unique to said receiver and wherein said second remote control device comprises externally operable selection means for selecting the predetermined control signal to be transmitted. 2) An immobilisation system as claimed in claim 1, in which the second remote control device comprises means for determining the format of the predetermined control signal to be transmitted, from the vehicle's registration number, which is input using said externally operable selection means. 3) An immobilisation system as claimed in claim 1, in which the second remote control device comprises means for determining the format of the predetermined control signal to be transmitted, from the make and/or model of the vehicle, which is input using said externally operable selection means 4) An immobilisation system as claimed in any preceding claim, in which, the vehicle unit may be responsive to either a master control signal from the second remote control device or a control signal transmitted by the first remote control device . 5) An immobilisation system as claimed in any preceding claim, in which the vehicle unit will not respond to control signals from the second control unit, once the vehicle has been immobilised using first remote control device. 6) An immobilisation system as claimed in any preceding claim, in which the second remote control device comprises a directional aerial. 7) An immobilisation system as claimed in any preceding claim, in which the power of the signal transmitted by the second remote control device is substantially greater than the power transmitted by the first remote control device. 8) An immobilisation system as claimed in any preceding claim, in which the vehicle unit is arranged not to respond to control signals received from the first remote control device, once a control signal has been received from the second remote control device. 9) An immobilisation system as claimed in any preceding claim, in which the vehicle unit can be arranged to only partially immobilise the vehicle upon receipt of a control signal from the second remote control device. 10) An immobilisation system as claimed in claim 9, in which the second remote control device comprises means for selecting and/or varying the degree of immobilisation. 11) An immobilisation system as claimed in any preceding claim, in which the second remote control device comprises means for de-activating the immobiliser.

Inventors: HOWELLS DONALD GLANMOR, HOWELLS, DONALD, GLANMOR
Applicants: HOWELLS DONALD GLANMOR, HOWELLS, DONALD, GLANMOR
Application year: 1999
Main classification: B60R25
IPC codes: B60R25