Clutch Slip Torque Estimation for Friction Coefficient Tracking
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Solution Overview
Problem
Existing methods struggle to accurately and efficiently ascertain the characteristic variable of a clutch in a vehicle's drive train, particularly the coefficient of friction, which is crucial for maintaining operational safety and driving comfort, as it is difficult to evaluate and readjust due to temperature fluctuations and wear.
Innovation Solution
A method involving two electric motors, where one motor is connected to the clutch input and the other to the clutch output, allowing the clutch to enter a slipping state with a predefined rotational speed difference to determine the transmission torque, thereby enabling the assessment of the clutch's characteristic variable at shorter intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the clutch is operated in a slipping manner to adapt the coefficient of friction, then the characteristic variable can be ascertained, but the time required for ascertainment increases and the method cannot be performed frequently
Solution Approach 1:
The patent applies partial action by using a predefined, limited rotational speed difference between clutch input and output during the ascertainment process. Instead of requiring full clutch engagement or prolonged slipping operation, the method uses a controlled partial slipping state with specific speed differential to obtain sufficient measurement data for determining the characteristic variable, thereby reducing the time required while maintaining measurement accuracy.
2Reliability
If the clutch actuation is adjusted frequently to monitor transmission torque, then the characteristic variable can be updated more often, but the effect on vehicle operation becomes noticeable and may affect driving comfort
Solution Approach 1:
The patent implements periodic action by conducting clutch characteristic ascertainment at predetermined intervals or under specific operating conditions rather than continuously or frequently. The method triggers ascertainment based on criteria such as clutch slip detection, ensuring measurements are taken periodically when relevant data becomes available, thereby maintaining reliability without causing noticeable disturbances to driving comfort.
Solution Approach 2:
The system uses the natural operating conditions of the vehicle, specifically when clutch slip is already occurring during normal operation, to perform the characteristic ascertainment. Instead of requiring dedicated test procedures or artificial slipping conditions, the method leverages existing clutch slip events to gather necessary data, making the ascertainment process self-service and minimizing additional impact on vehicle operation.
3Measurement precision
If the rotational speed difference during slipping operation is increased to improve measurement accuracy, then the transmission torque can be determined more precisely, but the impact on vehicle dynamics and driving comfort increases
Solution Approach 1:
The patent optimizes the rotational speed difference parameter within a specific range to achieve the desired balance between measurement precision and minimal impact on vehicle dynamics. By carefully selecting and controlling the speed differential parameter during clutch slipping, the method ensures sufficient torque measurement accuracy while keeping the slipping intensity low enough to avoid noticeable effects on driving comfort and vehicle behavior.
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 method allows for precise and timely determination of the clutch's characteristic variable, enhancing the reliability and operational safety of the vehicle while maintaining driving comfort, with minimal external impact on vehicle users.
Implementation Method 1
A first electric motor (14) is connected to the clutch input (20) and to an internal combustion engine (12) and can assume generator operation, during which it is driven by the internal combustion engine (12)
Implementation Method 2
A second electric motor (24) is connected to the clutch output (22). The second electric motor (24) may regulate the second rotational speed
Implementation Method 3
The transmitted transmission torque of the clutch depends on the position of the actuating unit and on the coefficient of friction of the friction lining(s) of the clutch
Data Source
AI summary
A method ascertains a characteristic variable of a clutch installed in a drive train of a vehicle for transmitting a transmission torque between a clutch input and a clutch output. A first electric motor is connected to the clutch input and to an internal combustion engine and can assume generator operation, during which it is driven by the internal combustion engine. A second electric motor is connected to the clutch output. The clutch input can have a first rotational speed and the clutch output can have a second rotational speed. The transmission torque during generator operation is ascertained by activating the clutch to adopt a slipping state and in doing so by setting a predefined rotational speed difference between the first and second rotational speed. The clutch input torque present at the clutch input is then ascertained and the transmission torque is determined depending on the clutch input torque.