Detecting malfunction in cylinders of internal combustion engines
First Claim
1. Apparatus to detect malfunctioning in individual cylinders of an internal combustion engine, comprising:
- means for measuring the engine power time periods between crankshaft positions representing successive ignition times in successively fired cylinders of the engine,means to compute the individual deceleration rates between successive time periods,means to compute the average deceleration rate for each cylinder, andmeans to compare each individual deceleration rate with average deceleration rate for the corresponding cylinder, and to register a misfire when the individual deceleration rate exceeds the average by more than a predetermined limit value.
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Abstract
An apparatus for, and method of, detecting the uneven operation of the individual cylinders in an internal combustion engine, and for diagnosing the cause thereof. The engine is operated at any convenient idle speed. Power cycle time periods between successive ignition times are measured, the deceleration rates between successive time periods are then computed, and finally the average deceleration rates for the respective cylinders are computed. Misfires occurring randomly in cylinders are detected when individual deceleration rates exceed the average deceleration rate for the corresponding cylinder by a predetermined limit amount. Repeated malfunctioning in an individual cylinder is detected when the average deceleration rate for the weakest cylinder exceeds that for the strongest cylinder by a predetermined limit amount.
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Citations
7 Claims
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1. Apparatus to detect malfunctioning in individual cylinders of an internal combustion engine, comprising:
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means for measuring the engine power time periods between crankshaft positions representing successive ignition times in successively fired cylinders of the engine, means to compute the individual deceleration rates between successive time periods, means to compute the average deceleration rate for each cylinder, and means to compare each individual deceleration rate with average deceleration rate for the corresponding cylinder, and to register a misfire when the individual deceleration rate exceeds the average by more than a predetermined limit value. - View Dependent Claims (2, 3)
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4. The method of detecting malfunctioning in individual cylinders of an internal combustion engine, comprising the steps of:
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measuring the engine power time periods between crankshaft positions representing successive ignition times in successively fired cylinders of the engine, subtracting each measured time period from the following measured time period to determine individual deceleration rates between successive time periods, computing the average deceleration rate for each cylinder, and comparing each individual deceleration rate with the average deceleration rate for the corresponding cylinder, and registering a misfire when the individual deceleration rate exceeds the average by more than a predetermined limit value. - View Dependent Claims (5, 6)
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7. Apparatus to detect malfunctioning in individual cylinders of an internal combustion engine, comprising:
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means for measuring the engine power time periods between crankshaft positions representing successive ignition times in successively fired cylinders of the engine, means for subtracting each measured time interval from the following measured time period to detect whether there is a positive difference representing a momentary reduction in engine speed, comparator means producing a fault output whenever a time difference exceeds a predetermined limit value, to provide an indication of a significant fault in an individual cylinder, means for counting the number of faults occurring during a predetermined period, and comparator means for determining whether the number of faults exceeds a predetermined limit value above which engine performance is considered unsatisfactory.
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Specification