Low-Pressure EGR Valve Actuator Failure Detection
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Solution Overview
Problem
The existing low-pressure EGR system faces challenges in efficiently returning a large amount of EGR gas to the engine, leading to increased stress on mechanical stoppers and potential strength reduction, while also requiring dedicated actuators for each valve, resulting in cost and size increases.
Innovation Solution
The system incorporates a low-pressure EGR system with a common electric actuator and linking device that changes output characteristics to drive both the low-pressure EGR regulating valve and intake throttle valve, along with a mechanical stopper that limits the rotation range, allowing for failure detection without a dedicated sensor for the intake throttle valve and reducing stress on mechanical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the low-pressure EGR regulating valve is returned to the fully-closed position frequently during engine operation, then the valve can be properly positioned for operation, but stress is applied to the mechanical stopper many times causing strength reduction
Solution Approach 1:
The patent extracts the failure detection function from the mechanical stopper system by using a separate opening degree sensor. The sensor detects the opening degree of the low-pressure EGR regulating valve independently, allowing the mechanical stopper to focus solely on limiting the rotation range without bearing the additional burden of failure detection, thereby reducing stress on the mechanical stopper.
Solution Approach 2:
The patent introduces an opening degree sensor as an intermediary component between the low-pressure EGR regulating valve and the failure detection system. This sensor mediates the detection process, converting the valve's position into an electrical signal that can be analyzed by the control device, thereby eliminating the need for the mechanical stopper to directly engage in failure detection operations.
2Measurement precision
If a dedicated sensor is provided for the intake throttle valve, then failure detection accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent makes the opening degree sensor multi-functional by using it to detect both the opening degree of the low-pressure EGR regulating valve and, through inference, the opening degree of the intake throttle valve. The control device calculates the intake throttle valve's opening degree based on the detected EGR valve opening degree and predetermined relationships, allowing a single sensor to serve multiple detection purposes.
Solution Approach 2:
The system uses the opening degree sensor to detect the EGR valve position, and then the control device self-calculates the intake throttle valve's opening degree and failure status based on predetermined relationships stored in memory. This self-service approach eliminates the need for a separate dedicated sensor for the intake throttle valve.
3Reliability
If the mechanical stopper limits the rotation range to prevent over-rotation, then component protection is improved, but the opening degree detection range is restricted
Solution Approach 1:
The patent transitions from direct mechanical measurement to electrical signal-based measurement. The opening degree sensor detects the valve position through electrical signals rather than direct mechanical contact, allowing the system to accommodate the mechanical stopper's rotation limitation while still achieving accurate detection within the permitted range through signal processing and calculation.
Data Source
AI summary
In a low-pressure EGR system, a mechanical stopper limits a rotation range of a low-pressure EGR regulating valve at a limit opening degree of the low-pressure EGR regulating valve on its fully-open side and outside an EGR amount adjustment opening degree range of the low-pressure EGR regulating valve. After an engine is stopped, a failure detection unit rotates the low-pressure EGR regulating valve to its fully-open position to such an extent that rotation of a linking device is prevented by the mechanical stopper, and is configured to determine that a failure has occurred when an opening degree of the low-pressure EGR regulating valve detected by a low-pressure EGR opening sensor is different from the limit opening degree of the low-pressure EGR regulating valve.