Vehicle Transmission Sudden Deceleration Shift Control
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Solution Overview
Problem
Existing vehicle transmission systems face challenges in preventing engine over-revolution during sudden vehicle wheel deceleration and reacceleration, particularly when the vehicle wheel slips or locks during braking, leading to inappropriate shift stage selection that can adversely affect the clutch.
Innovation Solution
A transmission system that employs speed adaptive shift control and sudden deceleration adaptive shift control, where the system detects sudden deceleration and adjusts the shift stage to avoid excessively low shift stages, ensuring the clutch is not overloaded during reacceleration, by setting a shift-down lower limit and using a half-clutch mode to manage clutch engagement and disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If downshifting is prohibited when the vehicle wheel is in a slipping state due to braking operation, then engine over-revolution is avoided, but reacceleration after deceleration may be performed at a high shift stage that is not suited for the low vehicle speed
Solution Approach 1:
The control unit preliminarily determines a shift stage lower than the speed adaptive shift stage during sudden deceleration events. This preliminary action ensures that when the vehicle subsequently reaccelerates, the transmission is already in an appropriate lower shift stage, preventing the problem of reacceleration at a high shift stage that would be unsuitable for the low vehicle speed.
Solution Approach 2:
The system dynamically adjusts the shift stage selection based on the vehicle's operational state. During sudden deceleration, the control unit selects a shift stage that is lower than what would be normally selected based on speed alone, creating a dynamic adaptation to the unusual driving condition that balances both over-revolution prevention and future reacceleration needs.
2Speed
If shifting is performed to a low shift stage during sudden deceleration, then the shift stage matches the low vehicle wheel speed, but engine over-revolution occurs when the clutch is engaged after braking is weakened
Solution Approach 1:
The control unit performs a preliminary determination of the shift stage during the sudden deceleration event, selecting a stage that accounts for both the current low wheel speed and the anticipated reacceleration. This preliminary action prevents the need to downshift to an excessively low stage that would cause engine over-revolution upon clutch re-engagement.
Solution Approach 2:
The control unit continuously monitors the vehicle wheel speed and braking state, using this feedback to dynamically adjust the shift stage selection. The feedback mechanism ensures that the selected shift stage appropriately balances the current speed condition with the need to prevent engine over-revolution during subsequent clutch engagement.
3Stability of the object's composition
If shifting is performed to a high shift stage during sudden deceleration, then the current shift stage is maintained, but the shift stage becomes unsuitable for reacceleration at low vehicle speed
Solution Approach 1:
The system dynamically adjusts the shift stage selection based on the detected sudden deceleration condition. Rather than maintaining the current high shift stage statically, the control unit dynamically selects a lower shift stage that is more appropriate for the changed vehicle state and anticipated reacceleration, thereby improving adaptability while maintaining operational stability.
Data Source
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AI summary
A transmission system for vehicle includes a clutch (3) disposed in a power transmission path (6) between an engine (2) and a vehicle wheel (5), a transmission (4) disposed in the power transmission path (6), a clutch actuator (11), a shift actuator (13), a vehicle wheel speed sensor (16), a sudden deceleration detecting unit (S1) that detects a sudden deceleration of the vehicle wheel (5) based on an output signal of the vehicle wheel speed sensor (16), and a shift control unit (10). The shift control unit (10) executes an ordinary shift control (S2 to S9) to shift to a speed adaptive shift stage associated with the rotational speed and to execute, when the sudden deceleration detecting unit (S1) detects the sudden deceleration of the vehicle wheel (5), a sudden deceleration adaptive shift control (S10 to S19)to shift to a shift stage lower than an actual shift stage at the point of detection of the sudden deceleration and higher than the speed adaptive shift stage associated with the rotational speed.