Vehicle Transmission Control Apparatus for Wheel Spin Prevention
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Solution Overview
Problem
In vehicles with automatic transmissions, when wheel spin occurs, shift prohibition control can lead to overspeed of the input shaft due to rapid wheel speed increase after tire grip recovery, especially when the gear position is fixed at 1st and brake release results in wheel lock followed by tire grip recovery.
Innovation Solution
A control apparatus that prioritizes lower limit speed ratio control when either a wheel lock or wheel spin condition is met before the respective control's cancellation condition is satisfied, allowing the transmission speed ratio to be limited to a higher ratio than the lowest speed ratio, preventing overspeed by adjusting the gear position based on vehicle body speed during wheel lock and spin events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shift prohibition control is executed to prevent wheel spin, then wheel spin is suppressed, but input shaft overspeed occurs when tire grip recovers after wheel lock
Solution Approach 1:
The control apparatus changes the speed ratio parameter dynamically based on vehicle body speed during wheel lock conditions. When wheel lock is detected, the system selects a speed ratio higher than the lowest ratio, and when tire grip recovers, it transitions to a lower speed ratio, preventing input shaft overspeed while maintaining wheel spin prevention effectiveness
Solution Approach 2:
The system dynamically adjusts the transmission speed ratio based on real-time detection of wheel lock and tire grip recovery conditions. By making the speed ratio variable rather than fixed, the system adapts to changing traction conditions to prevent both wheel spin and input shaft overspeed
2Reliability
If gear position is held in 1st during shift prohibition, then wheel spin control is effective, but rapid wheel speed increase causes input shaft overspeed when brake is released
Solution Approach 1:
The system changes the speed ratio parameter from the lowest ratio to a higher ratio during wheel lock conditions. This parameter change limits the maximum speed of the output shaft, thereby preventing the input shaft from exceeding its speed limit when tire grip recovers after brake release
Data Source
AI summary
An electronic control unit is configured to, when the electronic control unit determines that any one of a first condition and a second condition is satisfied, preferentially execute lower limit speed ratio control. The first condition is a condition that, after the electronic control unit starts shift prohibition control, a wheel lock has occurred before a condition for cancelling the shift prohibition control is satisfied. The second condition is a condition that, after the electronic control unit starts the lower limit speed ratio control, a wheel spin has occurred before a condition for cancelling the lower limit speed ratio control is satisfied.