Engine Control Apparatus Transient Air-Fuel Ratio Mapping Error Compensation
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Solution Overview
Problem
Existing control systems for internal combustion engines with small displacement face challenges in maintaining accurate air-fuel ratio control due to issues like offset displacement, temperature drift, and sludge accumulation, leading to increased exhaust emissions, especially during transient operating conditions.
Innovation Solution
A control apparatus that calculates a control input by correcting a feedforward input using a feedback correction value, modifying operational state parameters and correlation models to ensure accurate fuel injection, even in transient states, thereby compensating for mapping errors caused by these issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is used to correct mapping errors, then control accuracy is improved, but responsiveness during transient states deteriorates
Solution Approach 1:
The system pre-calculates and stores correction values in a correction map during steady-state operation, so that when transient conditions occur, the pre-prepared correction data can be immediately applied without waiting for feedback control to respond, thus maintaining both accuracy and responsiveness
2Speed
If feedforward control is used for quick response, then responsiveness is improved, but control accuracy deteriorates due to mapping errors
Solution Approach 1:
The system uses feedback control to detect mapping errors by comparing actual sensor readings with expected values, then updates the correction map to compensate for these errors, ensuring that feedforward control remains accurate while maintaining its fast response characteristics
3Ease of operation
If throttle valve opening sensor is used to calculate basic injection amount, then ease of operation is improved, but reliability deteriorates due to offset displacement and temperature drift
Solution Approach 1:
The correction map acts as an intermediary that translates the throttle valve opening sensor signal into an accurate basic injection amount by applying pre-calculated correction factors that compensate for sensor drift and offset errors, maintaining both simplicity and reliability
Data Source
AI summary
A control apparatus capable of ensuring high control accuracy even if a controlled object is in a transient state, when a control input is calculated based on a value obtained by correcting a value calculated by a feedforward control method using a value calculated by a feedback control method. The control apparatus calculates a fuel correction coefficient such that an output from an oxygen concentration sensor converges to a target output, and multiplies a basic injection amount by the coefficient to calculate a fuel injection amount. The basic injection amount is selected from three values according to the cause of a mapping error. Two of them are calculated by searching respective maps according to corrected throttle valve opening values and engine speed. The other is calculated by multiplying a value obtained by searching a map according to the opening and the speed by a correction coefficient.