Electric Friction Clutch Touch Point Detection From Motor Current
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Solution Overview
Problem
Existing friction clutches, such as those described in WO 2008/096438 A1, face challenges in precisely detecting the piston touch point and clutch touch point due to wear, which affects controllability and reliability.
Innovation Solution
An electric friction engagement device is designed with a cam device and an electric actuator, including a shift motor and a reducer, to detect the piston touch point and clutch touch point by monitoring the output torque or current value of the shift motor, allowing for precise control and wear detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If friction plates are used until wear exceeds limit, then productivity is improved by continuous operation, but reliability deteriorates due to seizure risk
Solution Approach 1:
The system performs preliminary detection of wear-related parameters (piston touch point, clutch touch point) before actual breakdown occurs. By monitoring these parameters during operation and detecting anomalies that indicate approaching wear limits, the system enables preventive maintenance before seizure happens, thus maintaining both continuous operation and reliability
2Productivity
If friction plates wear, then productivity is maintained through continued use, but measurement precision deteriorates as touch points change
Solution Approach 1:
The system continuously monitors parameters related to touch points (piston touch point, clutch touch point) during operation and provides feedback on their status. By detecting changes in these parameters that indicate wear, the system can identify when measurement precision is deteriorating due to wear, enabling timely intervention while maintaining productivity
3Reliability
If wear detection is implemented, then reliability is improved through timely maintenance, but device complexity increases due to additional sensors and monitoring systems
Solution Approach 1:
The system uses the existing shift motor's current characteristics to detect wear conditions. By analyzing the current waveform and its rate of change during normal operation, the system enables wear detection and reliability monitoring without adding separate sensors or complex detection equipment, thus improving reliability while minimizing increase in device complexity
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
The electric friction engagement device enables precise detection of the piston touch point and clutch touch point, enhancing controllability and reliability by preventing wear-induced breakdowns and ensuring timely maintenance.
Implementation Method 1
The elastic biasing member elastically biases the first friction plate and the second friction plate in a direction of pressing the first friction plate and the second friction plate against each other
Implementation Method 2
a friction clutch that transmits power through friction between opposing friction surfaces
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
A structure capable of detecting piston touch point and a clutch touch point is provided for an electric friction engagement device 7. When switching the electric friction engagement device 7 from a connected mode to a disconnected mode, a phase θ in a rotational direction of a drive cam 34 when an output torque T or current value A of a shift motor 66 begins to increase at a rate of increase equal to or greater than a first threshold value is detected as a piston touch point θp, and a phase θ in the rotational direction of the drive cam 34 when the rate of increase becomes equal to or less than a second threshold value is detected as a clutch touch point θf.