Engine Control Valve Dead Zone Movement for Sticking Prevention
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Solution Overview
Problem
Conventional control valve technologies fail to detect malfunctions when the actual opening agrees with the target opening, and prolonged constant openings lead to lube-oil loss and control valve sticking, particularly in EGR and throttle valves, causing motor bearing damage and operational issues.
Innovation Solution
A control device and method that dynamically changes the target opening within a dead zone range, where the flow rate and gas mixing ratios remain unchanged, to prevent prolonged constant openings and detect valve malfunctions, while maintaining engine operation conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the target opening of the control valve is maintained at a constant level for a long duration, then the engine operation remains stable, but the control valve may stick due to lube-oil loss and motor bearing damage
Solution Approach 1:
The control unit performs periodic to-and-fro movements of the valve shaft within the dead zone range even when the target opening remains constant. This periodic action prevents the control valve from sticking by maintaining motor bearing rotation and lube-oil circulation, while the movements are confined to the dead zone to maintain engine operation stability.
Solution Approach 2:
The system dynamically adjusts the valve opening within the dead zone range based on predetermined conditions (engine cooling water temperature, engine speed, engine load). By making the control valve opening dynamic rather than static, the system prevents sticking while maintaining effective engine operation through the dead zone characteristic.
2Reliability
If the target opening of the EGR control valve is 0, then the valve structure provides full closed function, but malfunction detection becomes difficult as actual opening agrees with target opening
Solution Approach 1:
The control unit performs preliminary to-and-fro movements of the valve shaft within the dead zone before attempting full closed operation. This preliminary action tests valve responsiveness and detects malfunctions early, while still allowing the valve to achieve full closed function when needed.
Solution Approach 2:
The control unit monitors the actual valve opening and compares it with the target opening. When the valve is commanded to close fully (target opening 0), the system uses feedback from position sensors and the periodic dead zone movements to detect whether the actual opening matches the target, thereby identifying malfunctions.
3Reliability
If the actual opening of the control valve agrees with the target opening, then the control system operates correctly, but malfunction cannot be detected under this condition
Solution Approach 1:
The control unit introduces periodic to-and-fro movements within the dead zone as a test signal. Even when normal operation shows agreement between actual and target opening, these periodic movements serve as a diagnostic tool to detect malfunctions by observing whether the valve responds appropriately to the commanded movements.
Solution Approach 2:
The system changes the valve opening parameter dynamically within the dead zone range for diagnostic purposes. By temporarily varying the opening parameter and observing the response, the system can detect malfunctions that would otherwise be hidden when the valve operates at a constant opening where actual and target values agree.
Data Source
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AI summary
A control device of a control valve used for an intake air-gas system of an engine, the device including, but not limited to: the control valve which is an intake air throttle valve provided in the intake air-gas system provided in the intake air-gas system of the engine to control the flow rate of intake air to the engine, or an EGR valve provided in the intake air-gas system of the engine to control the flow rate of EGR gas to the engine; and a control unit which determines a target opening of the control valve in response to the operation conditions of the engine, and controls the opening of the control valve so that the opening conforms with the target opening, wherein the control unit is configured so that, in a case where the target opening is maintained at a same level during over a fixed duration, the target opening is changed, in time, from the target opening which is determined in response to the operation conditions of the engine and controls the opening of the control valve, in order to prevent the control valve from being out of order as well as in order to detect a failure of the control valve.