CVT Clutch Slip Control Using Temperature-Based Usable Torque
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Solution Overview
Problem
Conventional drivetrains with continuously variable transmissions (CVTs) face challenges in preventing the prime mover from stalling and multiplying torque when wheels are partially or totally prevented from rotating, while also managing clutch temperature effectively.
Innovation Solution
A method and arrangement that control clutch slippage by determining usable torque based on clutch temperature data, allowing torque to pass through the clutch and causing it to slip when excessive torque is detected, with a main controller managing clutch slip and temperature to prevent stalling and maintain drivetrain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a torque converter is used to prevent stalling and increase torque, then the prime mover can stall prevention and torque multiplication, but the advantages of CVT are mitigated and clutch temperature increases
Solution Approach 1:
The system dynamically adjusts the usable torque parameter based on clutch temperature measurements. When temperature exceeds a threshold, the controller reduces the usable torque value, which in turn reduces the torque transmitted through the clutch, thereby controlling temperature rise while maintaining stall prevention capability through the CVT's inherent characteristics
Solution Approach 2:
The system implements a feedback loop where clutch temperature is continuously monitored and used to adjust the usable torque determination. The controller receives temperature data from sensors, compares it against thresholds, and dynamically modifies the torque management strategy accordingly, creating a closed-loop control system that balances stall prevention with temperature management
2Power
If clutch slippage is increased to prevent stalling, then torque multiplication is achieved, but clutch temperature and friction-related issues increase
Solution Approach 1:
The system applies partial slippage control by determining a reduced usable torque value when temperature thresholds are exceeded. This partial action allows sufficient torque multiplication to prevent stalling while limiting excessive slippage that would generate harmful friction and heat, achieving an optimal balance between power transmission and component protection
3Adaptability or versatility
If conventional torque converter is replaced with clutch-based system, then CVT advantages are maintained, but new challenges in temperature management arise
Solution Approach 1:
The controller acts as an intermediary between the clutch temperature sensor and the torque management system. It processes temperature data, determines appropriate usable torque values, and adjusts clutch operation accordingly, serving as a intelligent mediator that simplifies the overall temperature management while maintaining CVT adaptability and performance
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
This solution effectively prevents prime mover stalling and increases torque transmission while managing clutch temperature, enhancing the reliability and longevity of the drivetrain by controlling slippage and reducing friction-related issues.
Implementation Method 1
a clutch having a controllable slippage level between an input and an output
Implementation Method 2
a temperature sensor integrated with the clutch and configured to supply clutch temperature data to the controller
Data Source
AI summary
Clutch temperature management in a slip control method and arrangement for a drivetrain including a continuously variable transmission is described herein. The drivetrain includes a clutch that is so controlled as to slip when a torque higher than the usable torque attempts to pass through. The temperature data from the clutch is used to determine the usable torque. Accordingly, the clutch prevents the prime mover from stalling.