Anti-theft device for motor vehicles

Claim 2

In a motor vehicle having a basic electrical circuit, at least two switch-operated accessories and lead wires connecting each switch to the respective accessory, an anti-theft device comprising relay-operated means rendering said vehicle ignition inoperable; a transistor-transistor-logic integrated circuit of the two-input Exclusive OR Gate type having first and second input terminals and an output terminal, the first of said input terminals being electrically connected to the lead wire of one of said accessories and the second of said input terminals being electrically connected to the lead wire of the second of said accessories; and a normally open relay switch operably connected to said output terminal and arranged to activate said relay-operated means so as to inactivate the means rendering the vehicle ignition inoperable when one of said accessories is turned on and the other of said accessories is turned off.

Claim 3

An anti-theft device as set forth in claim 1, having a third and a fourth switch-operated accessory with lead wires connecting each switch to the respective accessory; a second integrated circuit of the Exclusive OR Gate type having two input terminals and one output terminal, the first of said input terminals being electrically connected to the lead wire of the third accessory and the second of said input terminals being electrically connected to the lead wire of the fourth accessory; a third integrated circuit of the positive-NAND Gate type having two input terminals and one output terminal interposed between the output terminal of the first integrated circuit with one input terminal connected thereto and the relay switch with the output connected thereto, the second input terminal of said third integrated circuit being connected to the output terminal of the second Exclusive OR Gate type circuit, and an inverter connected to the output of the third integrated circuit and having its output operably connected to the normally open relay switch.

Claim 4

An anti-theft device as set forth in claim 2 wherein the inverter is an integrated circuit of the 2-input positive-NAND Gate type and the two input terminals are electrically connected to each other and to the output terminal of the third integrated circuit.

Claim 5

An anti-theft device according to claim 1 in which a capacitor and a silicon controlled rectifier are interposed between the output terminal of the integrated circuit and the relay switch, one plate of said capacitor being connected to said output terminal; the rectifier having a gate connected to the other plate of the capacitor, its cathode connected to ground and its anode connected through the coil of the relay switch to the ignition switch.

Claim 6

An anti-theft device as set forth in claim 1 wherein the relay-operated means rendering the vehicle ignition inoperable is a switch interrupting the wire connecting the ignition switch to the ignition system.

Claim 7

An anti-theft device as set forth in claim 1 wherein the relay-operated means rendering the vehicle ignition inoperable is a normally closed valve in the fuel line between the tank and the motor.

Claim 8

An anti-theft device as set forth in claim 5 having a means to prevent hot wiring of the vehicle comprising a normally closed relay switch operably connected to said output terminal and connecting the wire from a point between the switch interrupting the wire and the ignition system to ground.

Claim 9

An anti-theft device for a vehicle having a hood latch as set forth in claim 1 having a solenoid adapted to release said hood latch, a solenoid switch for activating said solenoid and a second normally open relay switch operably connected to said output terminal and located between the solenoid and the solenoid switch.

Claim 10

In a motor vehicle having a basic electrical circuit, at least two accessory switches which normally can be turned on or off without affecting the operation of the ignition when the motor is running, and lead wires connecting each switch to an accessory, an anti-theft device comprising relay-operated means normally rendering the ignition of said vehicle inoperative; a normally open relay switch arranged to inactivate when closed, the means rendering the ignition inoperative; means activating said relay switch when one of said accessory switches is turned on and means for inactivating said relay switch when a second accessory switch is turned on.

Claim 11

In a motor vehicle having a basic electrical circuit, at least two accessory switches which normally can be turned on or off without affecting the operation of the ignition when the motor is running, and lead wires connecting each switch to an accessory, an anti-theft device comprising relay-operated means normally rendering the ignition of said vehicle inoperative; a normally open relay switch arranged to inactivate when closed, the means rendering the ignition inoperative; means activating said relay switch when one of said accessory switches is turned on and means for inactivating said relay switch when a second accessory switch is turned on.

Claim 12

In a motor vehicle having a hood latch, a basic electrical circuit, at least four accessory switches and lead wires connecting each switch to an accessory, an anti-theft device comprising relay-operated means normally rendering the ignition of said vehicle inoperable; a first transistor-transistor-logic integrated circuit of the Exclusive OR Gate type having two input terminals and an output terminal, the first of the input terminals being electrically connected to the lead wire of one of said accessories, the second of the input terminals being connected to the lead wire of a second accessory; a second integrated circuit of the Exclusive OR Gate type having a first input terminal connected to the lead wire of a third accessory and a second input terminal connected to the lead wire of a fourth accessory; a third integrated circuit of the positive-NAND Gate type having a first input terminal connected to the output of the first integrated circuit and a second input connected to the output of the second integrated circuit; a fourth integrated circuit of the positive-NAND Gate type having two inputs linked together and connected to the output of the third circuit; a capacitor having a first plate connected to the output of the fourth integrated circuit; a silicon controlled rectifier having a gate connected to a second plate of said capacitor, a cathode connected to ground and an anode; a relay coil connected at one end to the anode of the rectifier and at the other end to a lead wire connecting the ignition switch to the ignition system; a normally open relay switch interrupting said wire, said switch being operably associated with said relay coil so as to close the switch when current passes through said coil; a normally closed relay switch also operable by said relay coil connecting said wire at a location between the normally open relay switch and the ignition system to ground; a solenoid arranged to release the hood latch of the vehicle; a switch for activating said solenoid; and a second normally open relay switch operable by said relay coil and located between the solenoid and the solenoid switch.

Claim 13

In a motor vehicle having a hood latch, a basic electrical circuit, at least four accessory switches and lead wires connecting each switch to an accessory, an anti-theft device comprising relay-operated means normally rendering the ignition of said vehicle inoperable; a first transistor-transistor-logic integrated circuit of the Exclusive OR Gate type having two input terminals and an output terminal, the first of the input terminals being electrically connected to the lead wire of one of said accessories, the second of the input terminals being connected to the lead wire of a second accessory; a second integrated circuit of the Exclusive OR Gate type having a first input terminal connected to the lead wire of a third accessory and a second input terminal connected to the lead wire of a fourth accessory; a third integrated circuit of the positive-NAND Gate type having a first input terminal connected to the output of the first integrated circuit and a second input connected to the output of the second integrated circuit; a fourth integrated circuit of the positive-NAND Gate type having two inputs linked together and connected to the output of the third circuit; a capacitor having a first plate connected to the output of the fourth integrated circuit; a silicon controlled rectifier having a gate connected to a second plate of said capacitor, a cathode connected to ground and an anode; a relay coil connected at one end to the anode of the rectifier and at the other end to a lead wire connecting the ignition switch to the ignition system; a normally open relay switch interrupting said wire, said switch being operably associated with said relay coil so as to close the switch when current passes through said coil; a normally closed relay switch also operable by said relay coil connecting said wire at a location between the normally open relay switch and the ignition system to ground; a solenoid arranged to release the hood latch of the vehicle; a switch for activating said solenoid; and a second normally open relay switch operable by said relay coil and located between the solenoid and the solenoid switch.

Claim 14

An anti-theft device as set forth in claim 9 wherein the primary function of said switches is to control a standard electrical device normally present in motor vehicles whereby the presence of said switches does not disclose the presence of anti-theft device.

Claim 15

An anti-theft device as set forth in claim 11 wherein said switches control an electrical device selected from the group consisting of a radio, heater, light, turn indicator, tailgate motor, or air conditioner.