DCT Control Using Input Shaft Speed to Calculate Output Speed
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Solution Overview
Problem
In dual clutch transmission (DCT) systems without an output shaft speed sensor, a failed wheel speed sensor leads to incorrect gear coupling, causing clutch bursts when the vehicle is driven, as the controller lacks information to manage the output speed.
Innovation Solution
A control method that includes sensor checking, gear coupling confirmation, top stage coupling, output speed calculation, and shift stage arrangement to properly couple gears and prevent clutch bursts by calculating the output shaft speed using input shaft speed sensors, even when the wheel speed sensor fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the wheel speed sensor is not provided or fails, then the device complexity is reduced, but the reliability of gear coupling and clutch control deteriorates
Solution Approach 1:
The patent introduces an intermediary calculation method that uses the relationship between input shaft speed and gear ratios to derive output shaft speed and vehicle speed. Instead of directly measuring these parameters, the system uses the formula: output shaft speed = input shaft speed / gear ratio, and vehicle speed = output shaft speed × final drive ratio. This intermediary calculation approach allows the system to maintain reliable control without requiring additional sensors.
Solution Approach 2:
The system uses its own internal parameters (input shaft speed from the input shaft speed sensor and known gear ratios) to calculate the parameters that would otherwise require separate sensors. The control unit performs self-diagnosis and self-measurement by leveraging the mechanical relationship between input and output shafts through the gear train, making the system self-sufficient without external wheel speed sensor input.
2Device complexity
If the output shaft speed sensor is not provided, then the device complexity is reduced, but the measurement precision of output speed deteriorates
Solution Approach 1:
The patent replaces the mechanical measurement approach (using an output shaft speed sensor to directly measure rotational speed) with a calculation-based approach. The system substitutes the physical sensing mechanism with a computational method that derives output speed from input shaft speed and gear ratios, eliminating the need for the output shaft speed sensor while maintaining measurement accuracy through mathematical relationships.
3Ease of operation
If the controller calculates output speed using input shaft speed without knowing the actual output speed, then the ease of operation is improved, but the reliability of clutch control deteriorates
Solution Approach 1:
The patent implements preliminary verification of gear coupling status before allowing clutch engagement. The control unit checks whether the calculated gear ratio based on input shaft speed matches the expected gear ratio for the current driving conditions. This preliminary check ensures that the system only engages the clutch when the gear coupling is correct, preventing clutch burst even though the system operates without direct output speed feedback.
Data Source
AI summary
A dual clutch transmission (DCT) control method for a vehicle mounted with a DCT, which is not provided with an output shaft speed sensor, when a wheel speed sensor has failed, or the information cannot be controlled in a situation where shift gears are not coupled, properly couples the shift gears while preventing a clutch burst, and thus a controller can control DCT by calculating an output shaft speed of DCT.