Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2000-03-23
2001-08-21
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090100, C123S435000, C073S117020
Reexamination Certificate
active
06276319
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method for evaluating the course of the combustion chamber pressure and internal combustion engines.
It is known to ascertain the course of the combustion chamber pressures in the cylinders of an internal combustion engine with the aid of suitable sensors, and from this course to detect operating states of the engine and obtain trigger signals for controlling the engine. Typically, each cylinder of the engine is assigned a combustion chamber pressure sensor. A crankshaft sensor is also used, which furnishes an output signal that is representative for the crankshaft position. The two signals are evaluated jointly in the engine control unit. A camshaft sensor is no longer needed, since it is possible, especially after starting, to synchronize the crankshaft and camshaft position by linking the course of the combustion chamber pressure and the crankshaft sensor signal. A method in which the course of combustion chamber pressure is evaluated as a function of the crankshaft position, for the sake of cylinder detection and to generate signals required for ignition, is known from published, unexamined German Patent Application DE-OS 44 05 015. The cylinder detection and the detection of the crankshaft revolution in which the engine is located in a combustion cycle is performed in the known method by evaluating the pressure increase in a certain cylinder, for instance, and distinguishing between a pressure increase in the compression stroke and a pressure increase in the ensuing combustion. Since these values are different, the crankshaft revolution in which the engine is located can be ascertained. From this finding, control signals for the engine can be generated.
In the known method, an evaluation of the course of combustion chamber pressure to detect the valve control times, that is, in order to detect whether the outlet valve is opening or closing or whether the inlet valve is opening or closing, is not performed.
SUMMARY OF THE INVENTION
In keeping with these objects in accordance with the present invention a method for evaluating a combustion chamber pressure in an internal combustion engine includes performing measurements during normal engine operations, and evaluating incident combustion chamber pressure courses or events which depend on the combustion chamber pressure course and which characterize the valve control times.
The method of the invention has the advantage over the prior art that precise analysis of the course of combustion chamber pressure is performed, so that the valve control times can be ascertained with reference to the crankshaft position. To that end, characteristic events are evaluated from which unambiguously determined valve control times can be detected. For the valve control times of “outlet opens”, “outlet closes”, “inlet opens”, “inlet closes”, characteristic pressure courses are obtained which according to the invention are advantageously extracted from the course of the combustion chamber pressure.
It is especially advantageous that various valve control times can be ascertained by detecting the various associated characteristic events. Some valve control times can also be detected from a similar evaluation of the course of the combustion chamber pressure. A comparison with engine-typical characteristic variables stored in memory makes it possible to determine valve control times for a specific engine.
Further processing of the combustion chamber pressure signal before further evaluation, such as a differentiation or integration of the course of combustion chamber pressure, makes further ascertainments of valve control times advantageously possible. Taking additional engine operating conditions into account, such as the incidence of knocking combustion, and the ensuing additional signal processing, such as averaging, advantageously makes it possible to ascertain valve control times even if difficult conditions or operating states of the engine are occurring.
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Bellmann Holger
Walter Klaus
Lo Weilun
Robert & Bosch GmbH
Striker Michael J.
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