Sensing ignition by voltage monitoring
First Claim
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1. A method of sensing the ignition state of a vehicle engine, comprising the steps of:
- a) sampling a voltage level of a vehicle electrical system as powered by a vehicle battery without relying on other physical phenomena related to the engine, to obtain a current voltage sample;
b) determining if said current voltage sample has a sufficient drop from a preceding voltage sample;
c) determining if said current voltage sample is reliable by determining if a trend of voltage samples preceding said current voltage sample is consistent with said current voltage sample; and
d) determining if said current voltage sample is below a specified threshold from which an accurate inference is that the vehicle engine ignition is off.
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Abstract
A method of sensing vehicle engine ignition status is disclosed wherein samples of only the electrical system voltage levels are used. Sampling voltages that drop sufficiently (in magnitude and quantity over a period of time) will signify an “engine off” state.
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Citations
10 Claims
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1. A method of sensing the ignition state of a vehicle engine, comprising the steps of:
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a) sampling a voltage level of a vehicle electrical system as powered by a vehicle battery without relying on other physical phenomena related to the engine, to obtain a current voltage sample; b) determining if said current voltage sample has a sufficient drop from a preceding voltage sample; c) determining if said current voltage sample is reliable by determining if a trend of voltage samples preceding said current voltage sample is consistent with said current voltage sample; and d) determining if said current voltage sample is below a specified threshold from which an accurate inference is that the vehicle engine ignition is off.
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2. A method of sensing the ignition state of a vehicle engine, comprising the steps of:
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a) sampling a voltage level of a vehicle electrical system as powered by a vehicle battery without relying on other physical phenomena related to the engine, to obtain a current voltage sample; b) determining if said current voltage sample has a sufficient drop from a preceding voltage sample; c) determining if said current voltage sample is reliable; d) determining if said current voltage sample is below a specified threshold from which an accurate inference is that the vehicle engine ignition is off; and e) calculating a Running Average Voltage; wherein step b) determines if said current voltage sample has a sufficient drop from said preceding voltage sample by measuring whether the drop exceeds a prescribed Drop Delta below said Running Average Voltage. - View Dependent Claims (3, 4, 5, 6, 7)
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8. A method of sensing the ignition state of a vehicle engine, comprising the steps of:
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a) sampling a voltage level of a vehicle electrical system as powered by a vehicle battery without relying on other physical phenomena related to the engine, to obtain a current voltage sample; b) determining if said current voltage sample has a sufficient drop from a preceding voltage sample; c) determining if said current voltage sample is reliable; d) determining if said current voltage sample is below a specified threshold from which an accurate inference is that the vehicle engine ignition is off; and e) assigning default values to a plurality of parameters comprising Sample Interval, Sample Count, Transition Count On, Transition Count Off, On Threshold Voltage, Drop Delta and Off Threshold Voltage, and then tuning the parameters using guidelines and heuristics. - View Dependent Claims (9, 10)
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Specification