Vehicle immobilizer system for electronic engine control
First Claim
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1. An engine immobilizer for an engine in a vehicle, said vehicle having an ignition switch with at least an on position, said engine immobilizer comprising:
- a transponder coded with a unique security code to be in the possession of an authorized user of the vehicle;
a transceiver mounted in said vehicle for interrogating said transponder to obtain said security code;
at least one engine-running sensor mounted in said vehicle for detecting whether or not said engine is running; and
a controller coupled to said transceiver and said engine running sensor and storing at least one authorized security code, said controller having an armed state during which it disables said engine and having a disarmed state during which it does not disarm said engine;
wherein in response to an attempt to start said engine by activating said ignition switch, said controller in said armed state causes said transceiver to interrogate for said unique security code, detects existence of a match between said unique security code and said authorized security code, switches to said disarmed state if a match exists, and remains in said disarmed state while said engine is running; and
wherein said controller in said disarmed state monitors said engine-running sensor and switches to said armed state if said engine running sensor indicates that said engine has stopped running even though said ignition switch is not detected to be in said off position.
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Abstract
An engine immobilizer has an armed state in which it disables an engine and a disarmed state in which it does not disable the engine. The immobilizer disarms when an authorized security code is received from a transponder during an attempt to start the engine. The controller for the engine immobilizer monitors engine-running sensors and switches to the armed state if the engine-running sensors indicate that the engine is not running even though the ignition switch has not been detected to have been put in the off position.
44 Citations
16 Claims
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1. An engine immobilizer for an engine in a vehicle, said vehicle having an ignition switch with at least an on position, said engine immobilizer comprising:
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a transponder coded with a unique security code to be in the possession of an authorized user of the vehicle;
a transceiver mounted in said vehicle for interrogating said transponder to obtain said security code;
at least one engine-running sensor mounted in said vehicle for detecting whether or not said engine is running; and
a controller coupled to said transceiver and said engine running sensor and storing at least one authorized security code, said controller having an armed state during which it disables said engine and having a disarmed state during which it does not disarm said engine;
wherein in response to an attempt to start said engine by activating said ignition switch, said controller in said armed state causes said transceiver to interrogate for said unique security code, detects existence of a match between said unique security code and said authorized security code, switches to said disarmed state if a match exists, and remains in said disarmed state while said engine is running; and
wherein said controller in said disarmed state monitors said engine-running sensor and switches to said armed state if said engine running sensor indicates that said engine has stopped running even though said ignition switch is not detected to be in said off position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of controlling an engine immobilizer for an engine in a vehicle wherein an authorized user of said vehicle carries a transponder coded with a unique security code, wherein said vehicle includes a transceiver mounted in said vehicle for interrogating said transponder to obtain said security code, an ignition switch having at least an off position and an on position, a controller storing at least one authorized security code, and at least one engine-running sensor mounted in said vehicle detecting whether or not said engine is running, and wherein said controller has an armed state during which it disables said engine and has a disarmed state during which it does not disable said engine, said method comprising the steps of:
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interrogating for said unique security code in response to an attempt to start said engine by activating said ignition switch while in said armed state;
detecting existence of a match between said unique security code and said authorized security code, switching to said disarmed state if a match exists and remaining in said disarmed state while said engine is running;
while in said disarmed state, monitoring said engine-running sensor; and
switching to said armed state if said engine-running sensor indicates that said engine has stopped running even though said ignition switch is not detected to be in said off position. - View Dependent Claims (13, 14, 15, 16)
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Specification