Method and system for detecting the misfire of an internal combustion engine utilizing engine torque nonuniformity
First Claim
1. A method for detecting a misfire of a reciprocating internal combustion engine having a plurality of reciprocating components, at least one cylinder and a crankshaft, the method comprising the steps of:
- measuring angular velocity of said crankshaft to obtain an electrical signal representation thereof, said electrical signal containing data;
filtering said data to minimize the effects of random error and disturbances in said electrical signal to obtain filtered data;
calculating an M-dimensional torque nonuniformity vector derived from said filtered data;
computing at least one reference value of torque based on said torque nonuniformity vector;
estimating indicated torque provided by said at least one cylinder during a given engine cycle based upon said crankshaft angular velocity; and
comparing said at least one reference value with said indicated torque to obtain a misfire signal.
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Abstract
An improved method and system are provided for the detection of internal combustion engine misfires utilizing optimum signal processing. The method and system exploit a measurement of engine crankshaft angular velocity in conjunction with hybrid electronic signal processing. Once the angular velocity signal is conditioned to minimize the effects of random error and external disturbances, four alternate computationally efficient methods may be used to extract information pertaining to individual cylinder torque productions. Two of the methods employ extremal samples of the estimated torque or velocity waveform to obtain a random torque nonuniformity index or metric. The other two methods utilize a transformation into the frequency domain after the input data is first sampled and windowed to substantially lower probability of error. All of the methods provide an M-dimensional torque non-uniformity vector of individual cylinder performance for each individual engine cycle. A reference level for the nonuniformity index is derived for any given cylinder in any given cycle. This yields misfire detection at a relatively early time and is particularly suitable for transient engine operation.
111 Citations
17 Claims
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1. A method for detecting a misfire of a reciprocating internal combustion engine having a plurality of reciprocating components, at least one cylinder and a crankshaft, the method comprising the steps of:
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measuring angular velocity of said crankshaft to obtain an electrical signal representation thereof, said electrical signal containing data; filtering said data to minimize the effects of random error and disturbances in said electrical signal to obtain filtered data; calculating an M-dimensional torque nonuniformity vector derived from said filtered data; computing at least one reference value of torque based on said torque nonuniformity vector; estimating indicated torque provided by said at least one cylinder during a given engine cycle based upon said crankshaft angular velocity; and comparing said at least one reference value with said indicated torque to obtain a misfire signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for detecting a misfire of a reciprocating internal combustion engine having a plurality of reciprocating components, at least one cylinder and a crankshaft, the system comprising:
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means for measuring angular velocity of said crankshaft to obtain an electrical signal representation thereof, said electrical signal containing data; means for filtering the data to minimize the effects of random error and disturbances in said electrical signal to obtain filtered data; means for calculating an M-dimensional torque nonuniformity vector derived from said filtered data; means for computing at least one reference value of torque based on said torque nonuniformity vector; means for estimating indicated torque provided by said at least one cylinder during a given engine cycle based upon said crankshaft angular velocity; and means for comparing said at least one reference value with said indicated torque to obtain a misfire signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification