US 5,392,642 AGranted

System for detection of low power in at least one cylinder of a multi-cylinder engine

AssigneeCummins Engine Company, Inc.

InventorXuefeng T. Tao

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Abstract

Vibration sensors are used to monitor the resonant frequency of each cylinder of a multi-cylinder engine and the detection of an abnormal resonant frequency, i.e., one outside of an established range, is used as an indication that one or more specific cylinders is operating at an improper power level. Vibration signals associated with combustion in each cylinder can be used to perform FFT (Fast Fourier Transformation) with the combustion resonant frequencies for all engine cycles being determined and an averaged resonant frequency for each cylinder obtained. Shifts in the averaged resonant frequency or the detection of a zero resonant frequency for only one of the cylinders can be used as an indication that the cylinder with the shifted or zero resonant frequency is experiencing a low power condition, including misfiring.

Claims19

Dependent claims

System for detection of low power in at least one cylinder of a multi-cylinder engine having a plurality of individual cylinders, comprising:

vibration sensing means for detecting of vibration occurring during combustion in each of the individual cylinders of a multi-cylinder engine and producing output signals corresponding to the amplitude and frequency thereof,
signal conditioning means for limiting the output signals to a predetermined frequency range and from a defined portion of individual engine combustion cycles,
means for detecting the existence of resonant frequency peaks occurring in the individual engine cylinders during each of a prescribed number of consecutive engine cycles,
estimating means for estimating the frequency of any resonant frequency peak detected in said predetermined frequency range during said portion of the individual engine combustion cycles,
averaging means for averaging the frequencies of the resonant frequency peaks found for each individual cylinder for the prescribed number of engine cycles,
classifying means for classifying each of the cylinders as at least low power and normal power cylinders on the basis of the averaged frequencies of the resonant frequency peaks found for each individual cylinder and the distribution thereof over all of the cylinders, and
output means for issuing an identification of cylinders repeatedly classified as low power cylinders.

4 more elements

A method for detection of low power in at least one cylinder of a multi-cylinder engine comprising the steps of:

A) detecting of vibration occurring during combustion in each of the individual cylinders of a multi-cylinder engine via vibration sensors and producing output signals corresponding to the amplitude and frequency thereof,
B) limiting the output signals to a predetermined frequency range and from a defined portion of individual engine combustion cycles,
C) detecting the existence of resonant frequency peaks occurring in the individual engine cylinders during each of a prescribed number of consecutive engine cycles,
D) estimating the frequency of any resonant frequency peak detected in said predetermined frequency range during said portion of the individual engine combustion cycles,
E) averaging the frequencies of the resonant frequency peaks found for each individual cylinder for the prescribed number of engine cycles,
F) classifying each of the cylinders as at least low power and normal power cylinders on the basis of the averaged frequencies of the resonant frequency peaks found for each individual cylinder and the distribution thereof over all of the cylinders, and
G) issuing an identification of cylinders repeatedly classified as low power cylinders.

4 more elements

Dependencies are inferred from the claim text.