Measuring and testing – Engine detonation – Combustion signal compared to a fixed reference signal or...
Patent
1995-05-05
1996-03-05
Chilcot, Jr., Richard E.
Measuring and testing
Engine detonation
Combustion signal compared to a fixed reference signal or...
73116, 73 3508, 324380, G01M 1500, F02P 504, F02P 515, F02P 1704
Patent
active
054957575
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of international application PCT/EP92/00977, filed May 5, 1992, designating the United States, and published as WO 92/20912.
The present invention relates to a method and to a device for detection of ignition failures in an internal combustion engine. More particularly, the present invention also relates to an application of such a method and of such a device to the prevention of degradation of a "catalytic" oxidation converter for the exhaust gases of the engine.
Ignition failures in an internal combustion engine reveal various disorders which can affect either means dedicated to the ignition of the air/fuel mixture (coil, spark plug, short-circuit of the supply lines, etc.) or means of constituting the said mixture (carburettor, injector). Means of detection of such failures are thus used in order to correct these disorders by cleaning, adjusting or replacement of faulty parts.
Increasingly strict regulations in matters of air pollution lead, in addition, to considering the installation of such means of detection for other purposes. In fact, catalysts used in order to oxidize or reduce the exhaust gases of an engine are themselves liable to be degraded by injections of uncombusted fuel. In particular, when there is ignition failure in a cylinder of the engine, the fuel of the mixture introduced into the cylinder then passes directly on to the catalyst, without prior combustion. Such injections considerably diminish the effectiveness of the catalyst in its conversion of the exhaust gases, hydrocarbons, carbon oxides, nitrogen oxides, etc., into less polluting oxides. It is, therefore, advisable to protect the catalyst from such injections of uncombusted fuel, by, for example, cutting off the supply of fuel to an injector when ignition failures in a cylinder of an engine have been detected.
In order to detect such ignition failures, the use may be considered of a sensor sensitive to the pressure obtained in the cylinder. In the case of ignition failure, such a sensor does not detect the high pressure which normally results from the explosion of the air/fuel mixture. The sensors currently used to measure the pressure in an internal combustion engine cylinder suffer, especially due to the particularly severe environment in which they are installed, from inadequate robustness, reliability and accuracy, being very sensitive to temperature. They are, moreover, too expensive to be installed in an engine for a vehicle with a wide distribution.
The explosion of the air/fuel mixture which normally follows on from the generation of an ignition spark creates conditions of temperature and of pressure in an internal combustion engine cylinder which bring about ionization of the gases contained in the latter. The absence of such ionization thus reveals the prior occurrence of an ignition failure. In French Patent No. 91 04334, filed on the 10th April 1991 by the applicant, there is described a method for detection of an ignition failure, according to which, after extinction of an ignition spark, the presence or the absence of ionization of the gases contained in the cylinder is detected by supplying the spark plug for ignition of the mixture with a predetermined electrical voltage and by then detecting the possible passage of a current in the spark plug. The spark plug then serves as ionization probe, which renders the implementation of this method of detection particularly inexpensive.
For this implementation, there is proposed, in the above-mentioned patent application, a device comprising a distributor modified by the addition of diodes to permit the passage of the "ionization" current in the spark plug. The diodes must be able to withstand a very high inverse voltage during the spark ignition in the spark plugs and are thus fairly expensive. Moreover, in the case of accidental disconnection of a spark plug, the associated diode behaves as a capacitor, which can lead to its destruction under very high voltage.
Thus the aim of the present inven
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Atanasyan Alain A.
Guipaud Serge C.
Chilcot Jr. Richard E.
Dombroske George M.
Greenberg Laurence A.
Lerner Herbert L.
Siemens Automotive S.A.
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