System and method for cylinder power imbalance prognostics and diagnostics

摘要

A system and method for the diagnosis and prognosis of cylinder power imbalance in an internal combustion engine utilizes cylinder firing times to determine a differential value indicative of the power imbalance. This differential value identifies a cylinder power imbalance condition and can be used in a one dimensional or a two dimensional analysis to predict future engine performance. In one embodiment, a trend parameter is calculated from the differential values over several test sequences at periodic mileage of the vehicle. The rate and magnitude of change or deterioration of the engine performance is indicated by the trend parameter. In another embodiment, a two dimensional trend array is evaluated using singular value decomposition to arrive at an eigenvalue transformation matrix used to obtain two trend variables related to the two principal eigenvalues at a particular engine operating hour/mileage. In one specific embodiment, the two trend variables are converted to polar coordinates in which the polar radius rho is indicative of the severity of the imbalance condition and the polar angle theta is indicative of the cause or of a change of cause for the engine power imbalance.