Method and apparatus for controlling the operating parameters of an internal combustion engine
First Claim
1. A method of operating an internal combustion engine by controlling the magnitude of an operating parameter, said parameter being one of the class which includes fuel injection control pulses, ignition timing, exhaust gas recycle rate and the like, and comprising the steps of:
- monitoring the magnitude of state variables of the engine, said state variables being one or more of the class which includes engine speed, air flow rate, induction tube pressure, throttle valve position, exhaust gas composition and the like, and using the magnitude of said state variables to derive therefrom the appropriate setting for said operating parameter;
comparing at least one of said state variables temporarily with a set-point value for providing a feedback correction signal for said operating parameter;
and wherein said step of providing a feedback correction signal for said operating parameter occurs only when the engine operates in specific conditions and wherein the correction signal is maintained constant and equal to the last value obtained by feedback control when said engine is operated purely on the basis of said stored set of data of said operating parameter;
whereby errors due to wear and aging and other influences are compensated for.
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Abstract
In the operation of an internal combustion engine, certain operating parameters, for example the length of fuel injection pulses, the ignition timing and the exhaust gas recycle rate can be adjusted on the basis of information related to state variables of the engine, for example the engine speed, the induction tube pressure, the air flow rate and the like. In particular, the injection pulse length may be determined from data stored in a memory and addressed by a pair of numbers related to the instantaneous values of engine speed and air flow rate. This type of open loop control is rapid and may be very exact but does not account for long-range changes in engine behavior due to wear, etc. For this reason, additional circuitry senses a further state variable, for example, the oxygen content of the exhaust gas or the engine roughness, and uses this information in a feedback loop to generate a correction signal which is then applied in a rate multiplier to the basic fuel injection datum. The closed loop control is effective only in certain operational domains which are indicated by load-related conditions, e.g., the throttle valve opening.
48 Citations
20 Claims
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1. A method of operating an internal combustion engine by controlling the magnitude of an operating parameter, said parameter being one of the class which includes fuel injection control pulses, ignition timing, exhaust gas recycle rate and the like, and comprising the steps of:
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monitoring the magnitude of state variables of the engine, said state variables being one or more of the class which includes engine speed, air flow rate, induction tube pressure, throttle valve position, exhaust gas composition and the like, and using the magnitude of said state variables to derive therefrom the appropriate setting for said operating parameter; comparing at least one of said state variables temporarily with a set-point value for providing a feedback correction signal for said operating parameter; and wherein said step of providing a feedback correction signal for said operating parameter occurs only when the engine operates in specific conditions and wherein the correction signal is maintained constant and equal to the last value obtained by feedback control when said engine is operated purely on the basis of said stored set of data of said operating parameter; whereby errors due to wear and aging and other influences are compensated for. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for operating an internal combustion engine by controlling the magnitude of an operating parameter, said parameter being one of the class which includes fuel injection control pulses, ignition timing, exhaust gas recycle rate, and the like, comprising:
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means for detecting the magnitude of one or more state variables of said engine, said state variables being of the class which includes engine speed, air flow rate, induction tube pressure, throttle valve position, exhaust gas composition, and the like; and
for generating detection signals related thereto;control computer means for receiving at least two of said detection signals and for deriving therefrom the magnitude of said operating parameter; feedback circuit means, for receiving a further one of said detection signals and for comparing it with as set-point value and for providing, temporarily, a correction signal for correcting the magnitude of said operating parameter and wherein said further detection signal is the signal from an oxygen sensor located in the exhaust system of the engine and wherein said apparatus further comprises means for translating the signal from said oxygen sensor into a bivalent control signal and wherein said operating parameter is the length of control pulses for the fuel injection valves of said engine, and wherein said control computer means includes a digital memory in which values of said fuel control pulse lengths are stored as a function of the characteristics of said engine as defined by throttle valve position and engine speed;
whereby the magnitude of said control pulse is obtained by supplying prevailing values of said state variables, and wherein said control computer means provides a digital word related to the magnitude of the uncorrected fuel injection control pulse and wherein said apparatus further comprises a converter circuit receiving said digital word and also receiving a correction frequency from a further circuit which transforms said further detection signals and wherein said correction frequency and said digital word are used to generate a final fuel injection control pulse. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification