Dog Clutch Engagement Control Under Position Sensor Failure
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Solution Overview
Problem
The failure of sensors used to detect the position of a dog clutch sleeve prevents determination of the clutch's engagement or release, leading to potential failures in engagement and release control.
Innovation Solution
A vehicle clutch control method that executes clutch engagement or disengagement based on differential rotation thresholds, even when sensors fail, by adjusting these thresholds and using shift mechanisms to manage torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor is used to detect the position of the dog clutch sleeve, then the engagement and disengagement control can be accurately detected, but the system reliability deteriorates when the sensor fails
Solution Approach 1:
The patent introduces an intermediary mechanism (the shift mechanism and spring assembly) that physically mediates between the actuator and the dog clutch sleeve. This mechanical intermediary allows the system to detect engagement status through the movement of the shift mechanism itself rather than relying solely on the position sensor, thereby maintaining reliability even when the sensor fails.
Solution Approach 2:
The system uses its own operational characteristics (the movement of the shift mechanism and spring compression/extension) to self-diagnose the engagement status of the dog clutch. When the sensor fails, the control unit infers the engagement state from the differential rotation and the response of the shift mechanism, allowing the system to serve itself without external sensor input.
2Ease of operation
If the transmission torque is decreased to execute disengagement, then the dog clutch can be disengaged by the shift mechanism, but the disengagement detection becomes more difficult when the sensor fails
Solution Approach 1:
The patent implements feedback through the spring mechanism that naturally extends when torque is decreased, providing a restorative force that moves the shift mechanism and dog clutch sleeve back to the disengaged position. The control unit monitors the differential rotation and the response of this feedback mechanism to determine when disengagement has occurred, making detection feasible even without sensor input.
Solution Approach 2:
The system changes the torque parameter (decreases transmission torque) to facilitate disengagement, and the spring mechanism responds by changing its compression state. This parameter change creates a detectable physical response (movement of the shift mechanism) that can be used to infer disengagement status even when the position sensor is unavailable.
3Reliability
If the prescribed value for differential rotation is offset to the larger side during sensor failure, then engagement can be determined without sensor input, but the engagement threshold becomes less precise
Solution Approach 1:
The patent applies partial action by using a conservative threshold (offset to the larger side) that may not detect every possible engagement case but ensures that when the threshold is met, engagement is reliably confirmed. This approach prioritizes avoiding false positives over maximizing detection sensitivity, which is acceptable in safety-critical applications where sensor failure has occurred.
Data Source
AI summary
A clutch control method is used in a vehicle that has a dog clutch and an engagement sensor, which detects an engagement of a dog clutch. The clutch control method includes executing an engagement of the dog clutch when a magnitude of a differential rotation of the dog clutch is less than or equal to a prescribed value when the engagement sensor is normal and then determining the engagement of the dog clutch using the engagement sensor. The clutch control method further includes setting the differential rotation of the dog clutch to a value larger than the prescribed value when the engagement sensor has failed and then determining the engagement of the dog clutch based on a difference between the differential rotation of the dog clutch at a time of starting the engagement of the dog clutch and the differential rotation of the dog clutch.