Variable Compression Ratio Engine Self-Diagnosis
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Solution Overview
Problem
Existing variable compression ratio mechanisms in internal combustion engines can experience excessive load on components due to continued attempts to change compression ratio after being restricted by stoppers, often caused by controller failures, leading to inappropriate sensor-detected compression ratios.
Innovation Solution
A self-diagnosis system is implemented to detect and compensate for relative rotation between the arm and drive shaft, using stoppers to limit compression ratio ranges and calibrate sensor readings to ensure accurate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stoppers are provided to restrict movement of the piston-crank mechanism and mechanically limit the variable range of the compression ratio, then the compression ratio is prevented from becoming excessively high or low, but excessive load may be applied to each component part if the motor continues to attempt changing the compression ratio after being restricted by the stopper
Solution Approach 1:
The patent applies preliminary action by detecting relative rotation between the arm and drive shaft before excessive load damages components. The controller monitors the relationship between sensor detected values and actual compression ratio, and identifies abnormality (relative rotation) prior to catastrophic failure, allowing preventive action to be taken.
Solution Approach 2:
The patent implements feedback by continuously monitoring the relationship between sensor detected compression ratio values and actual compression ratio. When relative rotation occurs, the feedback mechanism detects the discrepancy and triggers abnormality determination, creating a closed-loop control system that prevents excessive load accumulation.
2Adaptability or versatility
If the motor continues to change the compression ratio after being restricted by the stopper due to controller failure, then the compression ratio control range is maintained, but inappropriate sensor-detected compression ratios occur and excessive load is applied to components
Solution Approach 1:
The patent uses feedback by continuously comparing sensor detected compression ratio values with actual compression ratio. When relative rotation occurs between the arm and drive shaft, the feedback mechanism detects the mismatch, allowing the system to identify when sensor readings become inappropriate while maintaining the compression ratio control range.
Solution Approach 2:
The patent introduces an intermediary diagnostic function that mediates between the sensor detection system and the actual compression ratio. This intermediary layer detects relative rotation by analyzing the relationship between detected values and actual values, serving as a bridge that identifies measurement inaccuracies without disrupting the overall control range.
3Strength
If relative rotation between the arm and drive shaft occurs, then the motor can continue operating without excessive load, but the relationship between the detected value of the sensor and the compression ratio becomes inappropriate
Solution Approach 1:
The patent applies feedback by monitoring the relationship between sensor detected values and actual compression ratio. When relative rotation occurs, the feedback system detects the information loss through the mismatch between detected and actual values, allowing the controller to identify when compression ratio information becomes inaccurate while protecting components from excessive load.
Solution Approach 2:
The patent introduces an intermediary diagnostic function that detects relative rotation by analyzing the discrepancy between sensor readings and actual compression ratio. This intermediary mechanism serves as an early warning system that identifies information loss before it becomes critical, maintaining component protection while alerting the system to measurement inaccuracies.
Data Source
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AI summary
A variable compression ratio internal combustion engine (1) is provided with a variable compression ratio mechanism (2) in which a mechanical compression ratio of the internal combustion engine (1) changes in accordance with a rotational position of a control shaft (18), a low compression ratio side stopper (50), a high compression ratio side stopper (60), a sensor (42) for detecting a rotational position of a drive shaft (22) of an actuator (24), and an arm (30) press-fitted onto the drive shaft (22). Relative rotation between the arm (30) and the drive shaft (22) occurs when a torque exceeding an upper-limit torque has been applied. The drive shaft (22) or the control shaft (18) is caused to move to restriction positions restricted by the respective stoppers (50, 60), and then a diagnosis on the presence or absence of the relative rotation is executed, based on the detected values at the respective restriction positions.