US 5,862,507 A · Real-time misfire detection for automobile engines with medium data rate crankshaft sampling

Abstract

A method and system for detecting engine misfire in an internal combustion engine. A data signal containing a plurality of groups of data points generated from sampling crankshaft rotational displacement over three predetermined angular sampling windows is generated. Each of the plurality of groups of sampled data points represents a cylinder firing event. The data signal is conditioned, and the plurality of groups of sampled data points are mapped into single misfire detection data points. The mapped single misfire detection points are then compared to a misfire detection dynamic threshold, and a misfire detection signal is output if the misfire detection points fall outside the dynamic threshold. The misfire detection system achieves high degree of accuracy through a multi-stage signal conditioning, multi-rate signal processing and statistical decision technology and a mixed size of window sampling strategy, and is capable of being installed on a large scale in motor vehicles through use of existing onboard automotive microcontroller technology.

Claims24

Dependent claims

A computer-implemented method of detecting misfire of an internal combustion engine, said engine including a plurality of cylinders and a crankshaft, said crankshaft having an angular velocity, comprising the steps of:

sensing for two firings of one of said cylinders the angular velocity of the crankshaft;
generating a data signal containing a plurality of groups of sampled data points, each of said plurality of groups of sampled data points representing a sensed crankshaft angular velocity for a particular cylinder firing event;
mapping each group of said plurality of groups of sampled data points into a single data point based upon a predetermined firing criteria;
determining a misfire detection dynamic threshold based upon firing signature signals of said engine;
comparing said mapped data point to said misfire detection dynamic threshold;
and
outputting a misfire detection signal if said mapped data point does not satisfy said dynamic threshold, said outputted misfire detection signal being indicative of a misfire of said engine.

4 more elements

A motor vehicle internal combustion engine misfire detection system for detecting misfire of an internal combustion engine, said engine including a plurality of cylinders and a manifold and a crankshaft, said crankshaft having an angular velocity, comprising:

a crankshaft velocity sensor that senses velocity of said vehicle crankshaft based on medium data rate crankshaft sampling and that generates a corresponding engine speed signal;
a manifold sensor that senses manifold absolute pressure (MAP) of said manifold and generates a corresponding manifold absolute pressure signal;
a signal processor that extracts average and fluctuation signal components from said engine speed and MAP signals for detecting both engine normal fire and misfire cylinder firing events;
a decimeter that, for a medium data sampling rate with M points sampled per cylinder firing event, where M is a positive integer greater than one, maps every M points into one mapped data point for misfire detection processing;
and
a dynamic threshold generator for generating a dynamic detection threshold based upon firing signature signals of said engine:
a dynamic decision sub-system connected to said threshold generator for determining if said signal represents an engine misfire cylinder firing event or an engine normal fire cylinder firing event based upon a comparison between said mapped data points and said generated dynamic detection threshold and that generates an output signal indicative thereof, said output signal being indicative of a misfire of said engine.

4 more elements

Dependencies are inferred from the claim text.

Real-time misfire detection for automobile engines with medium data rate crankshaft sampling

Life of this patent

Real-time misfire detection for automobile engines with medium data rate crankshaft sampling

Life of this patent

Abstract

Claims24