DCT Hunting Control via Engine Speed Comparison
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Solution Overview
Problem
Hunting occurs in vehicles with DCT transmission during low-speed starts, causing vehicle body wobble and abnormal sounds due to deceleration torque effects, which existing technologies fail to effectively control.
Innovation Solution
A hunting control device that detects engine speed and driving wheel rotational speed, calculates an NE converted value, and adjusts DCT clutch capacity by detecting deceleration and acceleration torque through throttle operation changes to suppress hunting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If DCT clutch capacity is controlled to suppress hunting during low-speed starts, then vehicle body stability is improved, but clutch wear increases due to frequent capacity adjustments
Solution Approach 1:
The control device performs preliminary detection of hunting conditions by comparing engine speed with NE converted value before hunting fully develops. By detecting the tendency toward hunting through speed difference comparison and throttle operation detection, the system takes preventive action to suppress hunting before it causes severe vehicle body wobble, thereby reducing the frequency and intensity of clutch capacity adjustments needed.
Solution Approach 2:
The system dynamically adjusts DCT clutch capacity based on real-time detection of hunting conditions through engine speed and NE converted value comparison. The clutch capacity is continuously optimized by modulating oil pressure according to the detected speed difference and throttle operation state, allowing the system to adapt to varying driving conditions and minimize unnecessary adjustments that would accelerate clutch wear.
2Speed
If DCT clutch capacity is frequently adjusted to respond to hunting, then hunting suppression responsiveness is improved, but control system complexity increases
Solution Approach 1:
The control system segments the hunting detection and control process into distinct functional modules: (1) engine speed detection, (2) NE converted value calculation based on gear ratio, (3) hunting condition determination by comparing speeds, (4) throttle operation detection, and (5) clutch capacity adjustment. This modular segmentation allows each module to operate independently with clear input-output relationships, simplifying the overall control logic while maintaining fast responsiveness.
Solution Approach 2:
The system implements feedback control by continuously monitoring engine speed and NE converted value, comparing them to detect hunting conditions, and adjusting clutch capacity accordingly. The feedback loop incorporates throttle operation detection to anticipate hunting tendencies, enabling proactive control adjustments that respond quickly to changing conditions without requiring complex predictive algorithms.
3Stability of the object's composition
If clutch capacity is increased to prevent hunting, then vehicle stability is improved, but acceleration performance deteriorates due to excessive torque reduction
Solution Approach 1:
Instead of applying full clutch capacity reduction whenever hunting is detected, the system applies partial capacity adjustments proportional to the detected hunting severity. By comparing engine speed with NE converted value and evaluating the magnitude of speed difference, the control device applies only the necessary degree of clutch capacity reduction to suppress hunting, avoiding excessive torque reduction that would compromise acceleration performance during normal driving conditions.
Data Source
AI summary
A basic clutch capacity calculating unit calculates a clutch capacity of the DCT applying an engine speed, a degree of throttle opening, and a front wheel vehicle speed to a map. The basic clutch capacity calculating unit further calculates the DCT basic clutch capacity by amending the basic clutch capacity based on an oil temperature and a water temperature. An NE converted value calculating unit calculates an NE converted value obtained by converting a vehicle speed into an engine speed with the front wheel vehicle speed and a DCT speed change stage as input parameters. A hunting detecting unit detects hunting by comparing the engine speed with the NE converted value when a throttle operation is detected. A DCT clutch capacity correcting unit makes decreasing correction of a DCT clutch capacity when hunting is detected for suppressing the hunting.