GB2286625A

GB2286625A - Vehicle bonnet lock

Info

Publication number: GB2286625A
Application number: GB9402551A
Authority: GB
Inventors: Malcolm John Lowther
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-02-10
Filing date: 1994-02-10
Publication date: 1995-08-23
Also published as: GB9402551D0

Abstract

An immobiliser for a motor vehicle comprises a switch remote from the ignition switch of the vehicle and connected to supply electrical current selectively to one or more solenoids to cause a bolt core 2 of the or each solenoid to move out of or into engagement with a complementary receptor 3. The or each solenoid is mounted either on the underside of a bonnet of the vehicle or on adjoining under-bonnet structure of the vehicle and the receptor or receptors are respectively mounted either on adjoining under-bonnet structure of the vehicle or on the underside of the vehicle bonnet. <IMAGE>

Description

Improvements in and relating to Apparatus for Immobili8ing Motor Vehicles This invention relates to immobilisers for motor vehicles and more especially, but not exclusively, to apparatus which operates electronically to prevent access to a closable compartment of a vehicle (eg an engine compartment) and which can also isolate the electrical system of the vehicle from the vehicles source of electrical power and/or activate an existing alarm system of the vehicle.

Theft of motor vehicles is an increasingly serious social problem which can be overcome through the fitment to vehicles of an immobilising system which cannot readily be circumvented by a person seeking to take or steal the vehicle. Immobilisers and alarm systems are of course well known, the latter giving rise to increasing complaints because of their tendency to be set off innocently by passers-by, animals or even inclement weather.

Immobilisers are also well known which set out to isolate a component of the vehicle's ignition circuit from, for example, the ignition coil of that vehicle. Increasingly, however, such immobilisers can readily be circumvented simply by "hot wiring" the vehicle's battery to its ignition coil.

The present invention sets out in one aspect to provide an immobiliser for a motor vehicle which cannot readily be circumvented without substantial damage to that vehicle and which in a preferred construction, operates to isolate the electrical system of the vehicle from its main power source, namely the battery, and/or is able to activate an alarm system fitted to the vehicle.

According to the present invention in one aspect there is provided an immobiliser for a motor vehicle which comprises a switch remote from the ignition switch of the vehicle and connected to supply electrical current selectively to one or more solenoids to cause a bolt core of the or each solenoid to move out of or into engagement with a complementary receptor, the or each solenoid being mounted either on the underside of a bonnet of the vehicle or on adjoining under-bonnet structure of the vehicle and the receptor or receptors being respectively mounted either on adjoining under-bonnet structure of the vehicle or on the underside of the vehicle bonnet.

Preferably the switch is operated either manually by a key through an aperture formed in the bonnet surface.

Alternatively, the switch maybe operated remotely through an electrically operated hand held transmitter.

The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which: Figure 1 illustrates features of a vehicle immobiliser in accordance with the present invention; and Figure 2 is a circuit diagram of a feature of the immobiliser illustrated in Figure 1.

In a preferred arrangement, immobilisers in accordance with the invention essentially comprise an electrically or electronically operated master switch which is fitted to the underside of a bonnet of a vehicle and which operates to drive core bolts of one or more solenoids which are accessible only when the bonnet is open into engagement with suitably dimensioned receptors mounted on the surrounding under-bonnet structure of the vehicle, eg a vehicles wings, front bonnet support or bulkhead.

Alternatively the receptors may be located on the underside of the bonnet with the solenoids mounted on the surrounding under-bonnet structure.

Preferably the switch is operated manually by means of a key connectable to the switch via a suitably shaped opening in the bonnet. Alternatively, the switch may be operated electronically though a hand-held transmitter.

Typically the solenoids and receptors are positioned at several locations below the bonnet, these locations including the sides and front of the bonnet. As will be appreciated, once activated, access to the inside of the bonnet can only be achieved with considerable damage to the vehicle.

The master switch is preferably soft mounted to the underside of the bonnet so that any undue force used to open the bonnet will cause the switch to fall from its mounting to the engine compartment interior thereby removing the ability to access the switch by means of the key.

A typical solenoid arrangement is illustrated in Figure 1. The solenoid illustrated comprises a coil connected to receive electrical current from the battery of the vehicle and a core bolt 2 which is urged by a coil spring 4 into engagement with a cylindrical latch 3. Thus, with no current flowing to the solenoid, the core bolt 2 remains resident within the latch. When current flows to the solenoid coil, the electromagnetic forces generated cause the core bolt to move away from the latch 3 against the-action of the spring 4 thereby releasing the core bolt from the latch. Electrical connections from a wiring loom of the vehicle to the solenoid are indicated by reference numeral 5.

The latch 3 is securely attached to a mounting on the under-bonnet structure of the vehicle and the solenoid is secured to the underside of the vehicle bonnet.

Thus the latch may be secured by welding or other conventional means to an adjoining wing or grill section, and/or to the bulkhead of the vehicle. Typically, at least three latches and solenoids will be employed, are secured to each wing and one to the vehicle grill structure. An additional latch may well be secured to the bulkhead of the vehicle. Of course, the solenoids could alternatively be secured to the vehicles under-bonnet structure with the latches secured to the underside of the bonnet.

It will be appreciated from the foregoing that the solenoid operates in the sense that when the ignition circuit of the vehicle is inactive, the core bolts are driven by the springs 4 into the latches 3. With the ignition circuit operative, two options are provided depending upon the setting of the ignition switch, the first being one in which the core bolts are retained within the latches 3 (ie the solenoids are inoperative) and the second being one in which the core bolts are withdrawn to provide access to the engine compartment (ie the solenoids are operative).

Figure 2 is a circuit diagram of the master switch.

The switch is indicated by reference numeral 6 and is connected by leads-7 to the solenoids. To enable the switch to be operated to withdraw the core bolts 2 in the event of battery failure or removal, a series of diodes 8 is provided in circuit diodes to provide power for withdrawing the core bolts via the master switch.

In use, on parking a vehicle fitted with an immobiliser in accordance with the invention, as soon as the ignition circuit is de-energized, the core bolts 2 are driven by the springs 4 into the latches 3 securely to lock the engine compartment of the vehicle. At the same time, the master switch operates to isolate the electrical circuits of the vehicle (ie the ignition circuit) from the vehicle's battery and to link into any alarm system fitted in the vehicle. Preferably this alarm system operates through the vehicle horn and/or lights.

In the event that someone enters the vehicle cabin unlawfully, it will immediately be apparent that no electrical power for hot wiring is available. Any attempt to rectify this loss of power by gaining access to the engine compartment by physical means is likely to be thwarted by the core bolts of the solenoids. In addition, the soft mounted switch will quickly fall away from the bonnet undersurface thereby preventing any attempt to operate the switch with an alternative key.

It will be appreciated that the foregoing is exemplary of immobilisers in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention.

Claims

1. An immobiliser for a motor vehicle which comprises a switch remote from the ignition switch of the vehicle and connected to supply electrical current selectively to one or more solenoids to cause a bolt core of the or each solenoid to move out of or into engagement with a complementary receptor, the or each solenoid being mounted either on the underside of a bonnet of the vehicle or on adjoining under-bonnet structure of the vehicle and the receptor or receptors being respectively mounted either on adjoining under-bonnet structure of the vehicle or on the underside of the vehicle bonnet.

2. An immobiliser as claimed in claims 1 wherein the switch is operated by a key through an aperture formed in the bonnet surface.

3. An immobiliser as claimed in claim 1 wherein the switch is operated remotely through an electrically operated hand held transmitter.

4. An immobiliser as claimed in any one of the preceding claims wherein the switch is soft mounted to the underside of the bonnet.