Variable Compression Ratio Control Device Angle Diagnosis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The VCR mechanism in internal combustion engines faces challenges in accurately determining the rotation angle of the control shaft due to potential slipping on the output shaft of the actuator or the control shaft, leading to errors in compression ratio control and failure to detect the reference position correctly.
Innovation Solution
A control device for the VCR mechanism that uses an angle sensor to detect the rotation angle of the output shaft of the actuator within a range of 0° to 360°, integrates changes in the rotation angle to determine the control shaft's position relative to a learned reference position, and compares this with a reference operation angle to diagnose any failures in the mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the absolute angle sensor is removed to reduce the size of the VCR mechanism, then the device complexity is reduced, but the measurement precision of the control shaft rotation angle deteriorates
Solution Approach 1:
The patent introduces a stopper mechanism as an intermediary physical reference point. The control shaft is rotated to press against the stopper mechanism, which provides a mechanical reference position. This allows the system to learn the reference position without requiring an absolute angle sensor, thus resolving the contradiction between device complexity and measurement precision.
2Ease of operation
If the control shaft is pressed to the stopper mechanism to learn the reference position, then the ease of operation is improved, but the reliability of reference position learning deteriorates due to potential slipping
Solution Approach 1:
The patent implements a feedback mechanism where the control device monitors the rotation angle of the control shaft during the reference position learning process. By comparing the monitored rotation angle with the expected rotation angle when pressed against the stopper mechanism, the system can detect slipping and determine whether the reference position has been successfully learned, thereby improving reliability.
3Ease of manufacture
If slipping occurs on the output shaft or control shaft, then the ease of manufacture is improved by simplifying the connection structure, but the measurement precision of the rotation angle deteriorates
Solution Approach 1:
The patent uses feedback control to monitor the rotation angle of the control shaft and detect discrepancies caused by slipping. The control device compares the actual rotation angle with the expected angle based on actuator output, and when a discrepancy exceeds a threshold, it diagnoses a slipping failure, thus maintaining measurement precision despite simplified connection structures.
Data Source
AI summary
A control device for a variable compression ratio mechanism for changing a compression ratio of an internal combustion engine by rotating a control shaft connected to an output shaft of an actuator, wherein with respect to a reference position, the control device determines the rotation angle of the control shaft by sequentially integrating the output values of an angle sensor that detects the rotation angle of the output shaft of the actuator in a range of 0° to 360° such that the rotation angle approaches a target angle. When the internal combustion engine is stopped, the control device rotates the control shaft to a high-compression-ratio side and a low-compression-ratio side, respectively, toward a stopper mechanism that defines the rotatable range and compares the determined rotation angle and a reference operation angle to diagnose whether a failure has occurred in the variable compression ratio mechanism.