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This paper presents a method of balancing the cylinder to cylinder torque fluctuation of an idling engine by controlling the individual spark timing. This method has the capability to compensate for individual fuel/air imbalance that might occur for example due to miscalibration of a fuel injector. The method is based upon noncontacting crankshaft angular speed flucuations and upon a control system that regulates individual spark timing in response to imbalance in that speed variation. The theory of the method is explained and experimental verification of the method is presented for a 4 cylinder engine.

This paper presents results of experimental results of a misfire detection system for cars equipped with gasoline fueled engines and both manual and automatic transmissions. A brief overview of the theory of the method and discussion of instrumentation is also given. The performance of the method for cars operated on a chassis dynamometer and on various roads is presented.

This paper presents several applications of a precise, moderate sampling rate measurement of the crankshaft angular position of a reciprocating IC engine. It is shown that the measurement can be made with a relatively inexpensive noncontacting sensor. Given sufficient precision and sampling rate, the various applications include: crankshaft reference position measurements for ignition timing (gasoline fueled engines), or injector timing (for electronically controlled diesel engines); crankshaft angular speed and acceleration measurements for estimating instantaneous indicated torque, and for diagnosing engine malfunctions. The torque estimate is potentially useful for engine control, to improve engine performance with respect to reducing cycle to cycle and cylinder to cylinder nonuniformity, and with respect to fuel economy.

This paper summarizes technical progress in a study of incipient fault detection in bus engines. The types of failures to which this method is applicable are those for which there is a gradual deterioration to failure over a relatively long time. In addition this method can also quickly isolate failed components. The fundamental basis of predicting such a fault is real time measurements of engine performance in the form of instantaneous brake torque and the nonuniformity in that torque. For our studies a number of buses were instrumented for real time performance measurements in simulated route operation. A data base was established for those measurements from which the statistical model for predicting failure has been developed. This paper explains the theory of the method, the instrumentation, the experimental results and the statistical model upon which failure prediction is based. The results of this study are applicable to an optimum strategy for maintenance scheduling.

This paper presents theory and experiments results for a noncontacting method of measuring reciprocating IC engine torque nonuniformity. This method yields an index of torque nonuniformity which is potentially useful for detecting abnormal engine operation and has important application for control and diagnostic functions. The nonuniformity index can be computed for each engine cycle if desired or averaged over many cycles. The method also has the capability of detecting intermittent abnormal operations. This paper explains the nonuniformity index and describes noncontacting instrumentation with which it can be measured. The results of experimental measurements of the nonuniformity index in actual operation of a vechicle equipped with an automatic transmission are presented. The statistical distribution of this index is shown to be such that abnormal engine operation can be reliably detected even if such operation occurs infrequently.

This paper discusses an inexpensive, non-contacting sensor for the measurement of the quasi-average torque of an internal combustion engine. The quantity which is actually measured by this sensor is a low-pass filter transformation of instantaneous developed torque having a bandwidth of about 9Hz. This method of torque measurement uses an inexpensive sensor which directly measures instantaneous crankshaft angular velocity. Electronic signal processing generates a signal which is proportional to instantaneous crankshaft angular acceleration. The relationship between engine developed torque and various transformations of this acceleration have been experimentally studied. This paper shows that certain of these transformations are highly correlated with the desired torque signal under transient as well as steady state operation. Transient operations which have been studied include changes in throttle position.