AUTOMATICALLY ARMED VEHICLE
ANTI-THEFT SYSTEM
CROSS-REFERENCE TO RELATED 5
APPLICATIONS
This application is a continuation-in-part of patent application Ser. No. 07/801,701, filed on Dec. 2, 1991, now U.S. Pat. No. 5,172,094.
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BACKGROUND OF THE INVENTION
The present invention generally relates to theft prevention systems and more specifically to a system for preventing the theft of motor vehicles.
Automobile theft has been a fact of life throughout 15 the history of the automobile. Heretofore, most thefts have occurred when the automobile is parked and unoccupied.
A recent phenomenon however, is theft of an automobile from an occupant, at gunpoint. A solution to the 20 automobile theft problem must address this new dimension of car theft. Conventionally, anti-theft systems require an occupant to arm or set the system before a theft can be deterred.
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SUMMARY OF THE INVENTION
The present invention solves the above stated problem by providing a vehicle anti-theft system in which actuation of the system does not require any action by an occupant of the vehicle. A basic premise underlying 30 the concept of the present invention is that an occupant is under extreme duress when approached by a thief and therefore incapable or ill advised to perform a physical act to activate an anti-theft system. In accordance with the present invention, the anti-theft system is automati- 35 cally armed at the end of a predetermined time period if an occupant does not properly deactivate (reset) the system. Once the anti-theft system is armed, the vehicle engine will only be able to properly operate properly near the engine's normal idling speed after a first actua- 40 tion of the brake pedal. Only proper resetting of both the vehicle disabling circuitry and the anti-theft system will deactivate (reset) the entire system so the vehicle can again be operated normally.
It is therefore an object of the present invention to 45 provide an improved vehicle anti-theft system which is automatically armed in response to a detected condition.
It is another object of the present invention to provide an improved vehicle anti-theft system which dis- 50 ables the vehicle enough to discourage a thief to abandon the vehicle shortly after theft.
It is another object of the present invention to provide a method of passively preventing a theft of a motorized vehicle, wherein the method provides for dis- 55 abling the vehicle in a manner which only permits the vehicle engine to operate properly near the engine idling speed once the anti-theft system is triggered and there is a detection of vehicle deceleration.
In accordance with the present invention, an auto- 60 matically armed motorized vehicle anti-theft system comprises a sensor latch means for providing an output signal in response to detection of either an attempt to start the vehicle motor or the opening of a vehicle door, with the engine running, or the ignition key "on" and a 65 timer means having a timer cycle. The timer means is responsive to detection of vehicle power activation and to the sensor latch means output signal for automati
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cally starting the timer cycle. When the timer cycle is complete, the timer means outputs a trigger signal. A means for generating a first reset signal is further provided to reset the sensor latch means and the timer means. A vehicle disabling means is responsive to the trigger signal for only permitting the vehicle engine to operate properly near the engine idling speed in response to detection of a vehicle brake actuation after the receipt of said trigger signal. The system further comprises a means for generating a second reset signal to reset the vehicle disabling means, wherein after the vehicle is disabled, the anti-theft system can only be reset and the vehicle operated normally again by the generation of both the first and second reset signals.
In further accordance with the present invention, a method for passively preventing a theft of a motorized vehicle comprises the steps of detecting power activation of the vehicle, detecting an attempt to start the vehicle motor or open a vehicle door, and in response to both of these steps, automatically initiating a predetermined time cycle. Subsequently, a determination is made concerning whether a first reset signal is generated. If no first reset signal is generated, a trigger signal is generated at the end of the time cycle. The vehicle is disabled so that the vehicle engine will only operate properly near the engine idling speed in response to the first detection of a vehicle brake actuation after the trigger signal has been generated. The method further comprises the step of detecting whether a second reset signal is generated after the vehicle is disabled, and in response to the generation of the second rest signal, the above-described time cycle and disabling step are restarted, wherein once the vehicle is disabled, normal operation can only be achieved after generation of both the first and second reset signals.
The present invention will be more fully understood upon reading the following detailed description of the preferred embodiment in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of the automatically set vehicle anti-theft system according to the present invention;
FIG. 2 is a detailed electrical schematic of a first embodiment of the system according to the present invention;
FIG. 3 is a detailed electrical schematic of the vehicle disabling circuit shown in FIGS. 1 and 2;
FIG. 4 is a detailed schematic of a second embodiment of the system according to the present invention;
FIG. 5 is a detailed schematic of a third embodiment of the system according to the present invention;
FIG. 6 is a flow chart illustrating the operation of the system according to the present invention; and
FIG. 7 is a detailed electrical schematic of the vehicle disabling circuit modified for use with a diesel engine.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENT OF THE
INVENTION
Referring to FIG. 1 there is shown a general block diagram of the present vehicle anti-theft system. The self-setting programmable timer circuitry 112 operates as a control element for automatically arming the system of the present invention. In operation, timer circuitry 112 is automatically set when vehicle power is
