EGR Valve Axis Alignment via Thermal Cycle Control
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Solution Overview
Problem
Internal combustion engine EGR valves experience thermal deformation during operation, leading to displacement of the valve member's central axis relative to the valve seat, resulting in significant EGR gas leakage even when the valve is closed, due to the generation of frictional forces and persistent gaps between the valve components.
Innovation Solution
An internal combustion engine controller that determines when the engine temperature equals the outside air temperature and performs a single opening/closing operation of the EGR valve to eliminate axis displacement, reducing the leakage by aligning the central axes of the valve member and seat, thereby minimizing the gap and frictional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the EGR valve is operated repeatedly to eliminate axis displacement, then the alignment between valve member and valve seat is improved, but electric power consumption increases
Solution Approach 1:
The controller performs the EGR valve operation when the engine is stopped and thermal deformation has subsided, preliminarily aligning the valve axes before normal operation begins. This timing choice eliminates the need for continuous operations during engine running, reducing overall power consumption while achieving proper alignment.
Solution Approach 2:
The controller changes the operational parameter (valve operation timing) based on engine temperature conditions. By detecting when the engine is stopped and temperature has stabilized, the system optimizes the alignment process to occur only when necessary, minimizing energy usage while maintaining precision.
2Manufacturing precision
If the EGR valve is operated multiple times to realign the valve axes, then the gap between valve components is reduced, but the duration of the alignment process increases
Solution Approach 1:
The system performs the alignment operation preliminarily when the engine is stopped, taking advantage of the natural cooling period. This approach consolidates the alignment process into a single event before operation begins, rather than requiring multiple operations during the engine's running time, thus reducing total time loss.
3Reliability
If the EGR valve operates frequently to maintain alignment, then the reliability of valve closure is improved, but the mechanical wear increases
Solution Approach 1:
The controller performs the alignment operation as a preliminary action when the engine is stopped, establishing proper valve alignment before normal operation. This eliminates the need for frequent corrective operations during engine running, thereby maintaining reliable valve closure while minimizing mechanical wear and extending component service life.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces EGR gas leakage by realigning the valve components, suppressing shaft deformation, and conserving electric power by limiting the number of valve operations, especially after the engine has stopped and the thermal deformation has been alleviated.
Implementation Method 1
the valve housing supporting the valve member may be thermally deformed, and the central axis of the valve member may be displaced relative to the central axis of the valve seat
Implementation Method 2
a frictional force is generated between the valve seat and the valve member, and thus a state is maintained in which the central axis of the valve member is displaced relative to the central axis of the valve seat
Data Source
AI summary
A controller is used in an internal combustion engine provided with an EGR device recirculating some of exhaust gas flowing in an exhaust passage to an intake passage as EGR gas. The EGR device includes an EGR passage and an EGR valve. The controller includes a CPU that controls opening and closing of the EGR valve. The CPU executes determining process of determining whether the temperature of the internal combustion engine is about the same as the outside air temperature, and an axis displacement eliminating process of opening and closing the EGR valve when it is determined that the temperature of the internal combustion engine is about the same as the outside air temperature in the determining process during the operation stop of the internal combustion engine.