Internal-combustion engines – Charge forming device – With fuel pump
Patent
1992-11-04
1993-11-16
Miller, Carl S.
Internal-combustion engines
Charge forming device
With fuel pump
123357, F02M 3704
Patent
active
052613780
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a device for producing a desired value for an engine control parameter of an internal combustion engine equipped with an electronic control.
INVENTION
A device concerned with the injective timing of a diesel engine that has an electronic diesel control ("EDC") is discussed in German Application No. DE-A-3540813. Particularly, it is concerned with the adjustment of the injection timing of a diesel engine equipped with EDC. The purpose of the device described in this document is to retard the fuel injection in the event of a rapid increase of power and to avoid or mitigate the temporary increase in engine noise which would otherwise take place. The injection retardation is fixed in terms of crankshaft angle and is sudden, although the subsequent advance is gradual and its onset is delayed. This device cannot retard the injection timing in the event of a sudden decrease in engine power and such a facility is in any case not needed for the purpose of reducing engine noise.
It is known also to adjust the injection timing in a diesel engine to achieve optimum fuel consumption, and to minimize emission of pollutants in the exhaust gas. It is further known with EDC to store a characteristic field of the desired injection timing in relation to one or more engine operating parameters, such as desired injected fuel quantity and engine speed.
When an engine is running in the steady state, i.e. when running at a substantially constant speed and load, the pollutant emission with the engine adjusted for optimum fuel consumption may still be within prescribed European standards although not the minimum obtainable in the steady state. Also, steady state running is usually only possible when driving outside towns, where pollutant emission is less critical. However, there is a likelihood of there being excessive or objectionable pollutant emission when increasing or decreasing the engine load (injected fuel quantity) with the injection timing adjusted for optimum fuel consumption.
SUMMARY OF THE INVENTION
The present invention is for obtaining optimum fuel consumption in steady state engine operation and acceptably low pollution emission when the engine is accelerating and decelerating.
The device according to the present invention stores characteristic fields of basic injection timing values for optimum fuel consumption and for minimum pollutant emission respectively.
According to the present invention, to minimize the risk of any jerkiness in operation, it is preferably that the changeover from either the static or dynamic mode to the other to be gradual.
The present invention includes command signal for triggering changeover between the static and dynamic modes and is useful for preventing too-frequent changes from one mode to the other.
Further, the present invention compensates for changes in cooling water temperature and compensates for changes in barometric pressure (altitude).
In the past, the desired value (SB.sub.des) is compared with a measured or actual value (SB.sub.act) in a closed servo-loop which contains a PI controller for operating the servo itself. In the case of a four-stroke multi-cylinder engine, the actual value (SB.sub.act) of the control parameter (SB), such as the injection timing, can only be measured once for every two engine revolutions. The PI controller, therefore, must be designed for a slow response time, particularly to prevent hunting or overshoot when the engine is idling.
To avoid the problem that there is no measured actual value (SB.sub.act) available during engine starting and when the vehicle is overrunning the engine, e.g. when going downhill, it is extremely advantageous to provide for open-loop "anticipatory" control as in the present invention. The anticipatory control, in the case of injection timing, can include timing maps for static and dynamic modes, with a separate timing map for engine starting being used.
The present invention is hereinafter particularly described in relation to the injection timing in the case of a diesel e
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Birk Manfred
Engel Gerhard
Fenchel Reinhard
Kull Hermann
Seher Dieter
Miller Carl S.
Robert & Bosch GmbH
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