Engine Air-Fuel Ratio Control for Torque Stability
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Solution Overview
Problem
Conventional internal combustion engine control methods face delays in air amount response to throttle movement, leading to torque and rotational speed variations when the air-fuel ratio is suddenly changed, affecting both engine performance and emission control.
Innovation Solution
A control device that dynamically adjusts the change speed of the required air-fuel ratio using a low-pass filter or averaging operations, determining the final air-fuel ratio based on predetermined conditions to minimize torque variations while maintaining exhaust gas performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the required air-fuel ratio is suddenly changed to improve exhaust gas performance, then emission control is enhanced, but torque and rotational speed variations occur due to air amount response delay
Solution Approach 1:
The control device predicts future air amount based on current throttle opening degree and its change rate, and determines the required air-fuel ratio in advance based on this predicted value. This preliminary action allows the air-fuel ratio to be set appropriately before the air amount actually changes, preventing torque variations while maintaining emission control benefits
Solution Approach 2:
The control device dynamically adjusts the required air-fuel ratio based on the predicted air amount, throttle opening degree, and throttle change rate. By making the air-fuel ratio determination dynamic rather than static, the system can respond appropriately to changing conditions without causing torque instability
2Reliability
If the throttle opening degree is adjusted to cancel torque variation when air-fuel ratio changes, then torque stability is maintained, but the response delay of air amount to throttle movement is exacerbated
Solution Approach 1:
Instead of reacting to torque variations after they occur, the control device predicts future air amount and determines the required air-fuel ratio in advance. This eliminates the need for corrective throttle adjustments that would further delay the air amount response
Solution Approach 2:
The control device uses feedback from the actual air amount, throttle opening degree, and throttle change rate to continuously update the predicted air amount and adjust the required air-fuel ratio accordingly, maintaining torque stability without exacerbating response delay
Data Source
AI summary
A control device for an internal combustion engine provided by the present invention is a control device which can satisfy both a requirement relating to exhaust gas performance of the internal combustion engine and a requirement relating to operation performance by properly regulating a change speed of a required air-fuel ratio, in the internal combustion engine which uses torque and an air-fuel ratio as control variables. The control device receives the requirement relating to the exhaust gas performance of the internal combustion engine, and calculates an air-fuel ratio which satisfies the requirement as a required air-fuel ratio. When a predetermined reduction condition is not satisfied, an original required air-fuel ratio is directly determined as a final required air-fuel ratio. However, when the reduction condition is satisfied, the change speed is reduced by processing the signal of the original required air-fuel ratio, and determines the required air-fuel ratio with the change speed reduced as the final required air-fuel ration. The reduction condition includes a condition that the change amount of the original required air-fuel ratio, in more detail, a change amount per calculation period is larger than a predetermined air-fuel ratio change determination value.