Engine Air-Fuel Ratio Control Apparatus for Sensor Degradation
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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 and changes in dynamic characteristics, leading to temporary increases in control errors, especially in transient operating states.
Innovation Solution
A control apparatus that calculates a control input using a correlation model modified on a region-by-region basis to compensate for control errors, incorporating error parameters and modification values to ensure accurate control even under conditions of reduced sensor reliability and dynamic changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a feedback control algorithm is used to compensate for control errors, then the air-fuel ratio can converge to the target air-fuel ratio, but it takes time before the control error is compensated for, resulting in temporary degradation of control accuracy
Solution Approach 1:
The patent applies preliminary action by calculating a preliminary fuel amount using a correlation model that relates reference parameters (intake air amount, engine speed) to the fuel amount before feedback control is applied. This preliminary calculation provides an advance estimate that reduces the initial control error, allowing the feedback control to converge faster to the target air-fuel ratio.
Solution Approach 2:
The patent combines feedback control with feedforward control. The feedback control algorithm calculates an air-fuel ratio correction coefficient based on the difference between the actual and target air-fuel ratios, while the feedforward control provides a preliminary fuel amount estimate. This combination allows rapid initial response followed by precise convergence to the target value.
2Adaptability or versatility
If sensor detection signals drift due to temperature changes or component wear, then the reliability of detection results lowers, but the control system continues to operate with degraded parameters
Solution Approach 1:
The patent applies self-service by having the control system automatically detect deviations in the correlation model between reference parameters and controlled variables, and then automatically calculate modification values to correct these deviations. The system monitors its own performance and performs self-correction without external intervention, adapting to sensor degradation over time.
Solution Approach 2:
The patent changes parameters by introducing modification values that adjust the correlation model based on detected deviations. When sensor drift is detected, the system modifies the relationship between reference parameters and controlled variables by applying these modification values, thereby compensating for sensor degradation and maintaining accurate control.
3Measurement precision
If the correlation model deviates from actual correlations due to sensor reliability degradation, then control accuracy decreases, but modifying the model requires additional calculations
Solution Approach 1:
The patent applies local quality by calculating modification values specifically for regions where deviations are detected, rather than uniformly adjusting the entire correlation model. The system divides the operating range into regions and applies localized modifications based on detected deviations in each region, reducing unnecessary calculations while maintaining accuracy where needed.
Solution Approach 2:
The patent segments the correlation model into multiple regions based on operating conditions. By dividing the model into manageable regions and calculating modification values for each region independently, the system reduces the complexity of model modification while maintaining overall accuracy. This segmentation allows selective adjustment of only those portions of the model that require correction.
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 modified errors by multiplying e.g. an air-fuel ratio error estimated value by link weight functions, calculates basic local correction values such that the modified errors become equal to 0; calculates local correction values by multiplying the basic local correction values and the like by the link weight functions; calculates corrected valve lift by adding a lift correction value, which is the total sum of the local correction values, to a value of valve lift; calculates a first estimated intake air amount for feedforward control of an air-fuel ratio, based on 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 based on these.