Wet Clutch Torque Control for Oil Overheating Limits
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Solution Overview
Problem
Conventional clutch units in motor vehicles experience overheating during high-speed operation, leading to discontinuation of all-wheel drive and reduced driving performance, as existing systems fail to manage heat effectively within the wet-running friction clutch.
Innovation Solution
A method for controlling the clutch unit that calculates heat inputs and outflows to determine a maximum admissible clutch torque, limiting the current torque to prevent excessive oil heating, thereby maintaining controlled all-wheel drive operation and improving driving dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the motor vehicle operates with all-wheel drive at high speeds, then driving performance is improved, but the oil in the clutch unit becomes excessively hot
Solution Approach 1:
The control device dynamically adjusts the clutch torque parameter based on real-time thermal balance calculations. By monitoring heat inputs (friction heating, shear heating) and heat outflows (cooling capacity), the system modifies the clutch torque to maintain oil temperature within safe operating limits while preserving all-wheel drive functionality at high speeds
Solution Approach 2:
The system implements a closed-loop feedback mechanism where the control device continuously calculates the thermal balance of the clutch unit and adjusts the clutch torque accordingly. This feedback loop prevents oil overheating by reducing torque when heat accumulation exceeds cooling capacity, while allowing full performance when thermal conditions permit
2Power
If the clutch torque is increased to maintain all-wheel drive, then driving dynamics are improved, but the oil overheating problem worsens
Solution Approach 1:
The control device dynamically modifies the clutch torque parameter based on real-time thermal balance calculations. By monitoring heat inputs (friction heating, shear heating) and heat outflows (cooling capacity), the system adjusts torque to maintain thermal safety while preserving power transmission capability
Solution Approach 2:
The system converts the potentially harmful effect of heat generation into useful information for control. By calculating thermal balance and predicting temperature development, the control device proactively adjusts clutch torque to prevent overheating before it occurs, transforming thermal constraints into a basis for optimized power management
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 approach ensures that all-wheel drive remains operational by maintaining a thermal balance, preventing oil overheating and enhancing motor vehicle driving behavior under elevated loads and high speeds.
Implementation Method 1
a wet-running friction clutch for controllably transmitting torque from an input element to an output element
Implementation Method 2
the clutch unit comprises oil for cooling the friction clutch
Data Source
AI summary
A method for controlling a clutch unit for a drive train of a motor vehicle, wherein the clutch unit comprises a wet-running friction clutch for controllably transmitting torque from an input element to an output element of the clutch unit, wherein the clutch unit comprises oil for cooling the friction clutch, wherein heat inputs which contribute to heating the oil of the clutch unit are calculated, heat outflows which contribute to cooling the oil of the clutch unit are calculated and, as a function of the heat inputs and heat outflows, a maximum admissible clutch torque is calculated, and wherein the current clutch torque of the friction clutch is limited to the maximum admissible clutch torque.