Shift Control Device Preventing Unintended Movement During Idling Stop
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Solution Overview
Problem
In vehicles with shift-by-wire mechanisms and idling-stop systems, unexpected movement can occur when the engine restarts from an idling-stop state, particularly when the reverse travel range is selected, as drive power is generated without the driver's intention, risking the vehicle to move backward.
Innovation Solution
A shift control device that includes a selection means, switching control means, and braking means, which switches the automatic transmission to a neutral or parking range when the vehicle is not braked and the reverse travel range is selected during an idling stop, preventing unintended movement by ensuring no drive power is transmitted to the wheels, and optionally uses a gradient detecting means to further prevent movement on slopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the reverse travel range is selected during an idling stop and the engine is automatically restarted, then drive power is generated, but the vehicle may start to move rearward unexpectedly
Solution Approach 1:
The control unit proactively prevents harmful vehicle movement by monitoring the transmission range and brake status before engine restart. When the reverse range is selected during idling stop without brake application, the system preemptively switches to neutral or parking range to block drive power transmission, thereby preventing the harmful effect of unexpected vehicle movement before it can occur.
Solution Approach 2:
The system performs a preliminary safety check by detecting the transmission range and brake operation status before allowing automatic engine restart. This preliminary action of verifying conditions and pre-switching the transmission range ensures that the engine can restart safely without causing unexpected vehicle movement, addressing the contradiction between automation and safety.
2Ease of operation
If the shift range is switched to reverse travel range during idling stop, then the vehicle can reverse, but drive power is generated at a timing the driver does not expect
Solution Approach 1:
The control unit continuously monitors the brake operation status and transmission range selection, providing real-time feedback control. When the reverse range is selected during idling stop, the system detects whether the brake is being applied and automatically adjusts the transmission range accordingly, ensuring that drive power is only transmitted when the driver intends vehicle movement through proper brake release.
Solution Approach 2:
The system dynamically adjusts the transmission range based on real-time brake status detection. Rather than maintaining a fixed shift range selection, the control unit adaptively switches between reverse, neutral, and parking ranges depending on whether the brake is applied, allowing reverse travel functionality while maintaining driver control safety through dynamic condition-based adjustment.
Data Source
AI summary
[Object] To provide a shift control device that, in a shift control device of a vehicle equipped with an idling-stop mechanism and a shift-by-wire mechanism, is capable of preventing setting off at a timing that the driver does not expect when returning from an idling-stop state.[Solution] The SBW-CU (40) that constitutes the shift control device (1), in the case of selection information for selecting the R range being output during an idling stop, switches the shift range of the automatic transmission (10) to the R range when the vehicle is braked, and switches the shift range to the N range or the P range when the vehicle is not braked and the shift range of the automatic transmission (10) is the D range. Also, the SBW-CU (40), in the case of selection information for selecting the R range being output during an idling stop, maintains the shift range without switching it when the vehicle is braked and the shift range of the automatic transmission (10) is other than the D range.