| 摘要 |
The compression of each cylinder of a reciprocating, internal combustion engine, expressed in a relative fashion as compared with the compression of another of the cylinders of the engine, is determined by sensing the peaks and valleys in an engine parameter which fluctuates commensurately with fluctuations in engine operating condition while cranking, such as starter current or voltage or instantaneous, subcyclic speed. The difference (D) between each peak and the preceding valley is measured, and these are filtered by averaging them with eight-tenths of the maximum difference, and each is expressed as a percentage of the maximum filtered difference. The time from one peak to the next is compared against some percentage of the average or expected peak to peak time (such as 130%), and if a peak is detected after the maximum allowed time, it is taken as being indicative of one peak being totally missing due to a very weak cylinder, so the difference value for the cylinder which was being looked for is taken to be zero, and the difference value for the cylinder whose peak actually was found is taken to be some fraction (such as 0.7) of the valley to peak difference actually calculated. Whenever the time out test does not indicate a failure, every difference measured is compared against three-tenths of the maximum difference which is expected, and if the difference is below that, the peak measured is used for the following valley, and the processing switches to look for a peak of the following cylinder.
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