Testing compression in engines from starter motor current waveform
AssigneeRCA Corporation
InventorEldon Marvin Sutphin, Jr.
Life of this patent
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Abstract
The relative compression in the cylinders of an internal combustion engine is tested by analyzing the starter motor current waveform when the engine is cranked with the ignition or the fuel inhibited. In asymmetrical engines, where the compression strokes of individual cylinders are unequally spaced in time, the starter current waveform may contain double-hump cycles. The area under each double-hump cycle is integrated, and the integration peaks are compared. The compression in one or more cylinders is deficient if the minimum integration peak is less than the maximum integration peak by a significant percentage such as 15 percent or more.
Claims4
Apparatus to detect unsatisfactory compression in individual cylinders of an internal combustion engine having compression strokes, comprising
- means for detecting the starter motor current waveform when the engine is cranked with the ignition or fuel inhibited, said waveform having cycles each corresponding with at least one compression stroke,
- means for integrating the area under each of said cycles to produce corresponding integration signals, and
- means for comparing the amplitudes of the smallest and largest integration signals and indicating when their ratio is less than a predetermined value, whereby to register unsatisfactory compression in at least one of the cylinders of the engine.
A method to detect unsatisfactory compression in individual cylinders of an internal combustion engine having compression strokes, comprising the steps of
- detecting the starter motor current waveform when the engine is cranked with the ignition or fuel inhibited, said waveform having cycles each corresponding with at least one compression stroke,
- integrating the area under each of said cycles to produce corresponding integration signals, and
- comparing the amplitudes of the smallest and the largest integration signals and indicating when their ratio is less than a predetermined value, whereby to register unsatisfactory compression in at least one of the cylinders of the engine.
Dependencies are inferred from the claim text.