Measuring ignition timing using starter current
First Claim
1. Apparatus for measuring the ignition timing of an internal combustion engine while cranking the engine with the starter motor, comprisingmeans coupled to the starter motor circuit to derive a waveform representing starter motor current fluctuations having peaks due to compression in individual cylinders,means to generate from said waveform a current peaks signal indicating the times of current peaks,means coupled to the ignition circuit to generate a points openings signal indicating the times of points openings, andmeans to compare said signals to obtain a time difference signal representing the lead or lag of the ignition relative to the starter current peaks, which are displaced known amounts at given cranking speeds from times of top dead center.
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Abstract
Apparatus for and method of measuring the ignition timing of an internal combustion engine while cranking the engine with the starter motor, and with the ignition inhibited. Starter motor current fluctuations are examined to determine the times of current peaks due to compression in individual cylinders. Means coupled to the ignition circuit determines the times of points openings. A time difference signal representing the lead or lag of the ignition relative to the starter current peaks is generated. The lead or lag is then related to the time of top dead center in terms of degrees.
8 Citations
10 Claims
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1. Apparatus for measuring the ignition timing of an internal combustion engine while cranking the engine with the starter motor, comprising
means coupled to the starter motor circuit to derive a waveform representing starter motor current fluctuations having peaks due to compression in individual cylinders, means to generate from said waveform a current peaks signal indicating the times of current peaks, means coupled to the ignition circuit to generate a points openings signal indicating the times of points openings, and means to compare said signals to obtain a time difference signal representing the lead or lag of the ignition relative to the starter current peaks, which are displaced known amounts at given cranking speeds from times of top dead center.
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6. The method of measuring the ignition timing of an internal combustion engine while cranking the engine with the starter motor, comprising the steps of
deriving a waveform representing starter motor current fluctuations having peaks due to compression in individual cylinders, generating from said waveform a current peaks signal indicating the times of current peaks, generating a points openings signal indicating the times of points openings, and comparing said signals to obtain a time difference signal representing the lead or lag of the ignition relative to the starter current peaks, which are displaced known amounts at given cranking speeds from times of top dead center.
Specification