DCT Clutch Failure Diagnosis via Torque Comparison
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Solution Overview
Problem
Current diagnostic methods for clutch failure in dual clutch transmissions (DCTs) are inadequate, particularly in electric vehicle (EV) mode, as they cannot accurately determine clutch stickage due to engine shutdown, leading to potential misdiagnosis and adverse situations like engine stalling.
Innovation Solution
A diagnostic method involving a controller that compares wheel torque with driving load torque, releases a gear engaged with a non-drive shaft, and reconfirms vehicle operation to accurately judge transmission clutch failure, even in EV mode, by calculating and comparing torque values and adjusting gear engagement based on shift lever position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engine speed synchronization method is used to diagnose clutch failure, then diagnosis is simple and direct, but it cannot diagnose clutch failure in EV mode when engine is turned off
Solution Approach 1:
The patent changes the diagnostic parameter from engine speed (which is unavailable in EV mode) to wheel torque and driving load torque (which are available in all modes). By comparing wheel torque with driving load torque, the system can detect clutch failure regardless of whether the engine is running or the vehicle is in EV mode, thus resolving the contradiction between diagnostic simplicity and adaptability to different operating modes
Solution Approach 2:
The patent introduces wheel torque and driving load torque as intermediary parameters that can indicate clutch failure state without requiring engine operation. These intermediary parameters serve as a bridge between the diagnostic goal (detecting clutch failure) and the operational constraint (engine off in EV mode), enabling indirect but effective diagnosis
2Measurement precision
If gear is released to test clutch engagement, then clutch failure can be detected, but vehicle motion state may change causing false diagnosis
Solution Approach 1:
The patent performs preliminary confirmation of vehicle motion state before releasing the gear and again after releasing the gear. By checking whether the vehicle is in motion before the test and confirming the state after the test, the system ensures that the diagnostic test conditions are properly established and that any change in vehicle state is correctly interpreted, preventing false diagnoses
Solution Approach 2:
The patent uses feedback from vehicle motion state detection to control the diagnostic process. The controller continuously monitors whether the vehicle is in motion and uses this feedback information to determine when to perform the clutch engagement test and how to interpret the results, ensuring accurate diagnosis while accounting for actual vehicle operating conditions
Data Source
AI summary
A diagnostic method of determining clutch failure of a dual clutch transmission (DCT) includes comparing, by a controller, a wheel torque of a vehicle with a driving load torque of the vehicle, confirming, by the controller, whether or not the vehicle is driving, if, as a result of comparing step, the wheel torque is greater than the driving load torque, releasing, by the controller, a gear engaged with a non-drive shaft, if, as a result of the confirming step, the vehicle is in a stopped state, reconfirming, by the controller, whether or not the vehicle is driving, after the releasing step, and judging, by the controller, that a transmission clutch of the non-drive shaft fails, if, as a result of the reconfirming step, the vehicle is driving.