Engine Control Unit Intake Air Switching for Idle Speed Stability
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Solution Overview
Problem
Existing engine control systems experience variations in engine speed due to delayed increase in engine speed when water or oil temperature is low, leading to reduced engine speed and increased convergence time to target idle speed.
Innovation Solution
An engine control apparatus that adjusts intake air flow using a control unit to switch between two intake air amounts, with a larger amount used until the engine reaches target idle speed and a smaller amount used thereafter, based on temperature and operational conditions, to stabilize engine speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the amount of intake air is increased above the normal idling flow rate to increase engine speed during warm-up, then the engine speed increases to approach target idle speed, but the convergence time to target idle speed is extended when water or oil temperature is low
Solution Approach 1:
The control unit determines in advance whether engine friction is high based on water or oil temperature before the engine reaches target idle speed. When high friction is detected, the control unit preliminarily sets the intake air flow to a larger amount (first intake air flow) to compensate for the upcoming friction losses, preventing engine speed drops before they occur.
Solution Approach 2:
The control unit dynamically adjusts the amount of intake air based on real-time engine conditions. When engine speed approaches target idle speed, the control unit switches between first intake air flow (larger amount for high friction conditions) and second intake air flow (normal amount), optimizing the balance between overcoming friction and achieving stable idle speed.
2Extent of automation
If the amount of intake air is switched based on predetermined time elapsed, then the control system operates automatically, but the engine speed becomes unstable with momentary reduction when friction is high
Solution Approach 1:
The control unit continuously monitors engine speed and compares it with target idle speed. Based on this feedback, the control unit determines whether to switch between first intake air flow and second intake air flow. When engine speed approaches target idle speed, the control unit uses feedback to make precise switching decisions, preventing engine speed instability.
3Speed
If the timing of intake air change is switched to when target idle speed is reached, then the engine speed control is optimized, but engine speed temporarily increases above target when throttle is opened
Solution Approach 1:
The control unit determines in advance whether engine friction is high based on temperature conditions before the engine reaches target idle speed. When high friction is detected, the control unit preliminarily sets the intake air flow to a larger amount, preparing the engine for the friction losses that will occur when the throttle is opened and closed, thereby preventing engine speed drops.
4Speed
If feedback control is performed with smaller amount of intake air when throttle is returned, then the engine speed control responds quickly, but the engine speed reduced temporarily problem is not resolved
Solution Approach 1:
The control unit dynamically adjusts the amount of intake air based on real-time engine conditions. When engine speed approaches target idle speed, the control unit switches between first intake air flow (larger amount for high friction conditions) and second intake air flow (normal amount), optimizing the balance between overcoming friction and achieving stable idle speed.
Data Source
AI summary
An engine control apparatus includes a control unit configured to perform a feedback control based on a second amount of intake air until a engine speed reaches a target idle speed. The engine control apparatus then regulates the amount of intake air to an amount smaller than a predetermined second amount of intake air for a predetermined period when the engine speed exceeds the target idle speed, and then performs a feedback control based on a first amount of intake air. Such engine control apparatus minimizes variation in engine speed by reducing a convergence time of the engine speed to a target idle speed in switching control of the amount of intake air in a case where engine friction at a low temperature is high.