Internal-combustion engines – Combustion chamber means combined with air-fuel mixture...
Patent
1991-05-13
1993-11-30
Wolfe, Willis R.
Internal-combustion engines
Combustion chamber means combined with air-fuel mixture...
123425, F02P 515
Patent
active
052655741
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to engine knock control systems in which an operating parameter such as the ignition timing is varied during dynamic operation i.e. acceleration, to prevent acceleration knocking.
At high cooling water and/or intake temperatures, audible acceleration knocking can occur in internal combustion engines if the load is increased very quickly, i.e. during dynamic engine operation. Knocking can be eliminated by retarding engine ignition. Therefore it has been proposed to temporarily retard engine ignition during dynamic engine operation to prevent the occurrence of acceleration knocking. In conventional knock-control systems if dynamic engine operation is detected the ignition is retarded by a fixed amount. However, retarding ignition has an adverse affect on engine response (gas emission) and therefore it is desirable to retard ignition as little as possible. The known systems for preventing acceleration knocking retard the ignition each time dynamic engine operation occurs, regardless of the ambient conditions. Thus, there may be instances when the ignition is retarded unnecessarily or more than is necessary.
SUMMARY OF THE INVENTION
The object of the present invention is to overcome this disadvantage and optimize the amount by which the ignition is retarded during each engine operation.
The present invention provides a method of mitigating acceleration knocking in internal combustion engines comprising the steps of sensing acceleration of the engine and changing a particular engine operating parameter in response to the sensing of acceleration, characterized by the steps of detecting the occurrence of knocking during acceleration and adjusting the amount of change of the parameter for the next acceleration depending on whether or not acceleration knocking is occurring.
Preferably the operating parameter is the ignition timing which is retarded in response to the sensing of acceleration.
Preferably the detecting step includes examining the intensity of acceleration knocking and adjusting the amount of retardation or change of some other operating parameter in dependence on the intensity. The amount of change is preferably adjusted when the knock intensity is outside a predetermined range. The knock intensity may be examined at regular intervals during a predetermined time after the sensing of acceleration.
The method is applicable to diesel engines as well as spark ignition engines. In diesel engines the injection timing is adjusted to mitigate knocking.
The method of the invention as applied to a spark ignition engine ensures that during dynamic operation the ignition angle is retarded just enough to avoid knocking combustion. The method is adaptive in that the amount of retardation is optimized for the ambient conditions present during each engine operation (for example intake air temperature, cooling water temperature, fuel quality, deposits in the combustion space etc.)
A particular advantage-is that a better engine response can be achieved, particularly during warm running and when using knock resistant fuel.
For example, if a driver changes from normal fuel to knock-resistant fuel, the retardation of the ignition necessary for each acceleration may be significantly less. According to the invention, next time the engine is operated (i.e. the vehicle is driven) the amount of retardation will be adjusted at every instance of acceleration until the amount of retardation during acceleration reaches an optimum value.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1(a) to (e) illustrate the method of the invention graphically and
FIG. 2 is a flow chart de
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Philipp Matthias
Unland Stefan
Robert & Bosch GmbH
Striker Michael J.
Wolfe Willis R.
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