Multi-Clutch Transmission Gear Detection via Clutch Slip
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Solution Overview
Problem
Existing multi-clutch transmission systems face challenges in gear shifting without interference and interruption in tractive force, especially when position sensors fail, leading to potential vehicle immobilization and gear unavailability.
Innovation Solution
The method involves closing a first clutch to transfer torque between a drive machine and a sub-transmission, applying a drag torque to another sub-transmission via a second clutch, detecting clutch slip, and determining the current gear selection by evaluating this slip, allowing for reliable gear engagement even without position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors are used to detect gear engagement, then gear selection accuracy is improved, but system reliability deteriorates when sensors fail
Solution Approach 1:
The patent uses clutch slip as an intermediary indicator to indirectly detect gear engagement state. Instead of directly measuring gear position with sensors, the system evaluates the slip between clutch plates during engagement, which reflects the mechanical state of gear coupling. This mediator approach allows reliable gear detection without vulnerable position sensors.
Solution Approach 2:
The clutch mechanism itself provides the detection function through its slip characteristics. The clutch slip naturally occurs during gear engagement and disengagement, and this inherent mechanical behavior is utilized for self-diagnosis of gear state, eliminating the need for separate sensing systems.
2Measurement precision
If a drag torque is applied to the second sub-transmission via the second clutch, then gear selection determination accuracy is improved through clutch slip evaluation, but energy loss increases
Solution Approach 1:
The drag torque is applied only partially - specifically during the gear selection detection phase - rather than continuously. The torque is sufficient to generate measurable clutch slip for detection purposes but not excessive enough to cause significant energy waste or affect normal transmission operation.
Solution Approach 2:
The application of drag torque occurs periodically during gear selection events rather than continuously. The system applies torque to generate slip signal when gear engagement needs to be detected, then releases it, creating a periodic action pattern that balances detection needs with energy efficiency.
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 enables gear shifting without interference and maintains full gear availability, preventing tractive force interruptions and allowing starting from a standstill even with faulty position sensors, ensuring fail-safe operation and reduced breakdown risk.
Implementation Method 1
applying a drag torque to a second sub-transmission of the multi-clutch transmission, which is coupled to the first sub-transmission, via a second clutch of the multi-clutch transmission; detecting a clutch slip of the second clutch, which is dependent on the drag torque
Data Source
AI summary
A method for operating a multi-clutch transmission for a motor vehicle, having at least the following steps: a) closing a first clutch of the multi-clutch transmission, in order to transfer an input torque (M_k1) between a drive machine of the motor vehicle and at least one first sub-transmission of the multi-clutch transmission; b) applying a drag torque (M_k2) to a second sub-transmission of the multi-clutch transmission, which is coupled to the first sub-transmission, via a second clutch of the multi-clutch transmission; c) detecting a clutch slip of the second clutch, which is dependent on the drag torque (M_k2); and d) determining a current gear selection of the multi-clutch transmission by evaluating the clutch slip. The disclosure further relates to a multi-clutch transmission and to a motor vehicle having a multi-clutch transmission.