Motor vehicles – With means for promoting safety of vehicle – its occupant or... – By preventing unauthorized or unintended access or use
Patent
1988-11-14
1990-06-12
Bertsch, Richard A.
Motor vehicles
With means for promoting safety of vehicle, its occupant or...
By preventing unauthorized or unintended access or use
180284, B60R 2500
Patent
active
049324942
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a security system for a vehicle, serving to disable the fuel system.
Known vehicle security systems generally rely upon door locks to prevent theft of the vehicle. Nowadays this does not afford sufficient protection, because all too often a thief has the expertise to break into the vehicle, "hot wire" the ignition and drive away.
In accordance with this invention, there is provided a vehicle security system comprising a code entry module and a decoding module, the decoding module being a sealed module mounted within or for mounting within a fuel tank of the vehicle and arranged so as normally to disable the vehicle fuel system and further arranged to respond to a predetermined access code being entered on the code entry module to enable the fuel system for normal running of the vehicle.
In a preferred embodiment, the code entry module preferably comprises a keypad requiring a predetermined 4-digit code to be entered. Only if the correct code is entered will outputs be activated for energising the vehicle fuel pump, or opening the fuel pump valve, and for enabling the ignition coil.
An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawings, in which:
FIG. 1 is a block diagram of a vehicle security system;
FIG. 2 is a diagram showing a fuel module of the security system mounted within a vehicle fuel tank and controlling a fuel pump also mounted in the tank; and
FIG. 3 is a diagram showing a fuel module incorporating a fuel valve and mounted within a vehicle fuel tank.
Referring to FIG. 1 of the drawings, there is shown a security system for a vehicle comprising a keypad module 10 and a fuel module 20. The keypad module 10 is intended to be mounted on the vehicle facia and comprises a keypad 11 for entry of a predetermined numerical access code to enable the vehicle fuel system, and an encoder/transmitter unit 12 coupled to the keypad output terminals. The keypad module 10 is a self-contained unit incorporating the electronics and an indicator LED 13. This unit also has a termination 14 for receiving a 6 volt or 12 volt supply, a termination 15 providing a signal from an AND gate 16 for enabling the ignition coil and a termination 17 for providing a signal to energise an external audible warning device such as a buzzer. The keypad module 10 is connected to the fuel module 20 by a 3-wire screened cable 30.
The fuel module 20 is a totally encapsulated or sealed unit intended to be mounted inside the fuel tank to inhibit any tampering. The fuel module comprises a decode circuit 21 connected to one input of a comparator 22, the other input of which is connected to a code select unit 23 (into which an individual code is preset at manufacture). The output of comparator 22 controls a switch 24 serving to connect the 6 or 12 volt supply on terminal 25 to a fuel pump or fuel valve via a terminal 26 and, over the third line of the cable 30, to the indicator LED 13 and to one input of AND gate 6, which receives the power supply at its other input.
In use of the vehicle security system so far described with reference to FIG. 1, the fuel system must be enabled before the vehicle can be driven away. When the ignition switch is turned on, power is applied to both the keypad module and the fuel module to power the electronics in each of these. The power feed to the vehicle fuel pump or fuel valve is however still interrupted, so that no fuel is available to the engine. In addition, output termination 15 from the keypad module is inactive so that the ignition coil is disabled. This prevents starting of the engine and any short running of the vehicle relying on fuel left in the carburettor and fuel line, in particular avoiding the possibility of the vehicle running out of fuel and stopping in a traffic condition.
The correct 4-digit access code must be entered on the keypad 11, in reponse to which the encoder/transmitter unit 12 sends a corresponding signal over the cable 30 to the decode circuit 21 of the module. This circuit decodes
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Bertsch Richard A.
Schindler Edwin D.
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