Engine Air-Fuel Ratio Control Error Compensation
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Solution Overview
Problem
Existing control apparatuses for internal combustion engines face challenges in accurately controlling the air-fuel ratio due to degraded sensor reliability, leading to increased control errors, especially in transient operating states, as detection signal drift and mechanical component wear affect the accuracy of intake air amount calculations.
Innovation Solution
A control apparatus that calculates a control input using a correlation model to compensate for control errors by modifying the model based on an influence degree parameter, allowing for quick and accurate adjustment of the control input to maintain target air-fuel ratios, even under conditions of sensor reliability degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a first estimated intake air amount is calculated based on valve lift and cam phase in a low-load region, then control accuracy is improved in low-load conditions, but control error increases when sensor detection signals drift or mechanical components wear
Solution Approach 1:
The patent changes the calculation parameters from using raw sensor signals (valve lift and cam phase) to using corrected values that compensate for sensor drift and mechanical wear. The ECU calculates corrected valve lift and cam phase values by applying correction coefficients to the detected values, thereby maintaining accurate intake air amount calculation even when sensors and mechanical components degrade over time
Solution Approach 2:
The patent implements a feedback mechanism where the ECU continuously monitors the detected valve lift and cam phase, compares them against expected values or correction models, and applies real-time correction coefficients. This feedback loop ensures that the first estimated intake air amount remains accurate despite sensor drift and component wear by dynamically adjusting the calculation parameters
2Reliability
If feedback control is used to compensate for control error, then air-fuel ratio convergence to target is achieved, but response time is too slow during transient operating states
Solution Approach 1:
The patent applies preliminary action by calculating the first estimated intake air amount using valve lift and cam phase before actual combustion occurs. This allows the ECU to proactively adjust the fuel injection amount based on predicted intake air conditions, rather than waiting for feedback from air-fuel ratio sensors. The correction coefficients are applied in advance to compensate for expected sensor drift and mechanical variations
Solution Approach 2:
The patent introduces an intermediary calculation layer that uses valve lift and cam phase as intermediate parameters to estimate intake air amount. This intermediary approach allows the system to bridge the gap between mechanical valve actuation and actual air intake, providing faster response than direct air-fuel ratio feedback by using mechanical parameters that change immediately with valve actuation
Data Source
AI summary
A control apparatus which is capable of compensating for a control error properly and quickly even under a condition where the control error is temporarily increased e.g. by degradation of reliability of the detection results of reference parameters other than controlled variables, thereby making it possible to ensure a high accuracy of control. An air-fuel ratio controller of the control apparatus calculates an air-fuel ratio error estimated value and an error weight, calculates an modified error, calculates a basic lift correction value such that the modified error becomes equal to 0, calculates a lift correction value, calculates corrected valve lift by adding the lift correction value to valve lift, calculates a first estimated intake air amount for feedforward control of an air-fuel ratio according to the corrected valve lift, calculates an air-fuel ratio correction coefficient for feedback control of the air-fuel ratio, and calculates a fuel injection amount according to these.