Measuring and testing – Vehicle chassis – Steering
Utility Patent
1994-11-07
2001-01-02
Dombroske, George (Department: 2855)
Measuring and testing
Vehicle chassis
Steering
C073S115060
Utility Patent
active
06167755
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates a device for determining load in an internal combustion engine.
A device for determining load in an internal combustion engine is known and comprises a pressure sensor which is located in a combustion chamber of an internal combustion engine and which generates an output signal depending on combustion chamber pressure, a crankshaft angle sensor for detection of the crankshaft angle and processor means for determining the load from the output signal of the pressure sensor at predetermined crankshaft angles.
Information regarding engine operation is required for control of the internal combustion engine. This information is obtained with the help of suitable sensors. The important parameters for operation of the internal combustion engine such as ignition time, fuel injection times and exhaust gas feedback rates are determined according to this information and stored as a characteristic operating value array. The load and the rotation speed must be known to find the actual necessary information, since the characteristic operating values are engine load and rotation speed dependent.
Air flow rate meters, air mass meters, throttle valve sensors or suction pressure sensors are used as load sensors. The air flow rate of the air drawn into the cylinders is determined by the control unit of the internal combustion engine with the help of these highly accurate sensors. With this type of sensor however only the total air flow rate into all the cylinders is determined. It is not possible to determine the flow rate to each individual cylinder.
It is also possible to determine load using a combustion chamber sensor in each cylinder of the internal combustion engine. The combustion chamber pressure in the cylinder depends on the amount of gas which is compressed in the compression stroke and which is subsequently reacted. For example in the disclosure in German Published Patent Application DE-OS 35 27 856 the absolute pressure in a cylinder at a predetermined crankshaft angle is input as an input variable for calculation of the load. The equation of state for a real gas is used for this calculation.
It is also known from the disclosure in German Published Patent Application DE-OS 40 01 362 in connection with a method for load determination that the temperature of the air mass drawn into the cylinders is an important input variable in the equation used for calculating the load and thus must also be measured. Thus a temperature sensor is provided in addition to a load sensor (combustion chamber pressure sensor) and measures the temperature of the air drawn into the cylinders. These measured values are then used for an exact load determination.
Many problems exist in the state of the art methods for determination of absolute pressure. Absolute pressure sensors are required, which can hardly be provided for the conditions present in the internal combustion engine or only at very high cost, so that a load determined by combustion chamber pressure sensors is scarcely possible.
SUMMARY OF THE INVENTION
It is an object of the instant invention to provide a device for load determination in an internal combustion engine which does not have the above-described disadvantages.
This object and others which will be made more apparent hereinafter is attained in a device for determining load in an internal combustion engine comprising a pressure sensor located in a combustion chamber of an internal combustion engine which generates an output signal depending on combustion chamber pressure, a crankshaft angle sensor for detection of the crankshaft angle of the internal combustion engine and processor means for determining load from the output signal of the pressure sensor at predetermined crankshaft angles.
According to the invention the processor means includes means for determining the load from a pressure difference between combustion chamber pressures measured at two different predetermined crankshaft angles (x1,x2) or from two pressure integral values. The pressure integral values are obtained by integrating a pressure-proportional output signal of the pressure sensor between two different predetermined crankshaft angles. Absolute pressure values are not necessary.
The device according to the invention has the advantage that the load can be determined from the output signal of at least one combustion chamber pressure sensor or a combustion chamber pressure sensor for each cylinder economically and reliably. This is possible because the absolute pressure does not need to be determined, but only the relative pressure values, which are derivable from the output signal from the pressure sensor.
The load is thus determined in an advantageous manner from a pressure difference or an integrated pressure value during the compression stroke and, if necessary, also in the intake stroke. The measurement of an exact course of the pressure occurs only within a certain predetermined region of operation, advantageously during the first 360° crankshaft angle and then determinations are possible over the entire pressure range. This also means that errors such as temperature change, scatter and shift of the null point as well as thermal errors by combustion do not in themselves effect the load determination.
An additional advantage is that the phase shifts, which for example are caused by the dynamic upper dead point error, which are still present in the measurement of the evolution of the pressure, are automatically corrected when the pressure difference and/or integrated pressure values are used.
Additional features of the preferred embodiments are apparent from the description provided hereinbelow.
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patent: 4913118 (1990-04-01), Watanabe
patent: 4991554 (1991-02-01), Wataya
patent: 5116259 (1992-05-01), Demizu et al.
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patent: 5359883 (1994-11-01), Baldwin et al.
patent: 3527856 (1986-02-01), None
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Hudson and Nelson,University Physics, pp. 460, 461 and 464-468, Harcourt Brace Jovanovich, New York, 1982.*
Damson Eckhart
Denz Helmut
Herden Werner
Klenk Martin
Kuesell Matthias
Dombroske George
Robert & Bosch GmbH
Striker Michael J.
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