Engine ECU Throttle Valve Learning Control
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Solution Overview
Problem
The existing control apparatus for internal combustion engines fails to accurately update learned values for throttle valve opening degrees, leading to divergence and large variations in intake air volume control, especially between regions where engine rotation speed is lower or higher than idling speed, resulting in inefficient engine operation.
Innovation Solution
An electronic control unit estimates characteristic values indicating divergence from reference intake air volume, stores these values, calculates them for unlearned opening degrees by linear interpolation, updates learned values for higher idling rotation speed regions, and maintains values for lower speed regions by using the smallest completed learning degree, thereby reducing deviations and variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the learnt value is updated frequently in the opening degree region where engine rotation speed is equal to or greater than idling rotation speed, then the control accuracy for normal operation is improved, but the learnt value diverges significantly from the learnt value in the low-speed region, causing large variations in intake air volume control
Solution Approach 1:
The patent applies different update strategies to different opening degree regions. In the low-speed region (engine rotation speed below idling speed), the learnt value is updated only once during initial learning and then maintained fixed. In the normal operation region (engine rotation speed equal to or above idle speed), the learnt value is updated frequently based on actual operation. This local differentiation resolves the contradiction by allowing frequent updates where needed while maintaining stability in regions where updates would cause divergence.
Solution Approach 2:
The patent segments the throttle valve opening degree range into two distinct regions: a low-speed region where engine rotation speed is below idle speed, and a normal operation region where engine rotation speed is at or above idle speed. Each region has its own learnt value storage and update mechanism. This segmentation allows the system to apply appropriate update frequencies to each region, preventing divergence while maintaining control accuracy where needed.
2Loss of information
If the engine rotation speed is kept lower than idle rotation speed to enable learning in the low-speed region, then the learnt value for low-speed operation can be obtained, but the engine cannot maintain normal idling operation
Solution Approach 1:
The patent performs the learning action in advance during a specific initial period after engine start-up, before normal idling operation begins. During this initial learning phase, the engine is operated at low speed to collect learning data for the low-speed opening degree region. Once this preliminary learning is complete, the system transitions to normal idling operation with the learnt values fixed. This preliminary action resolves the contradiction by obtaining necessary learning data without compromising subsequent operational stability.
Solution Approach 2:
The patent implements a dynamic transition in the learning mechanism. During the initial period after engine start-up, the learning mechanism is active and the learnt value can be updated. After this initial period, the learning mechanism becomes inactive and the learnt value is maintained fixed. This dynamic behavior allows the system to adapt during startup while maintaining stability during normal operation, resolving the contradiction between learning and operational stability.
3Adaptability or versatility
If linear interpolation is used to calculate characteristic values for unlearned opening degrees, then the control can cover the full range of throttle valve openings, but large variations occur when interpolating between opening degrees with significantly different learnt values
Solution Approach 1:
The patent ensures that linear interpolation is performed between learnt values that are similar in magnitude by maintaining consistency in the low-speed region. Since the learnt value in the low-speed region is kept fixed and matches the characteristics of adjacent opening degrees, interpolation between nearby opening degrees produces accurate results. This local quality control prevents large variations in interpolated values while maintaining broad control coverage.
Data Source
AI summary
A control apparatus for an engine, the control apparatus includes an ECU. The ECU is configured to: (i) estimate a characteristic value indicating divergence from a reference value of an intake air volume, (ii) store the characteristic value as a learned value, (iii) calculate the characteristic values for an opening degrees for which learning has not been completed, (iv) learn the characteristics of the throttle valve and reflect the characteristics in control of the intake air volume, (v) update the learned value at which an engine rotation speed is equal to or greater than an idling rotation speed during an initial engine operation after initialization of the learned values, (vi) update the learned value at which an engine rotation speed is lower than an idling rotation speed, by storing a value equal to the learned value for the smallest opening degree for which learning has already been completed.