Vehicle Parking Lock Control for Plug-In Hybrid
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Solution Overview
Problem
In plug-in vehicles with a momentary shift lever, the parking lock is unintentionally unlocked when the charge connector is removed, especially if external objects like shopping bags are hung from the shift lever, causing the lever to remain in a drive position.
Innovation Solution
A control device that includes a detection unit for the shift lever position and a control unit that prohibits unlock processing if the shift lever has not returned to its home position when the external power supply is disconnected, allowing unlock only if the lever has been operated to a different shift position after disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the parking lock is unlocked based on the shift lever position after charge connector removal, then the vehicle becomes easily operable, but unintended unlocking occurs when external objects hang from the momentary shift lever
Solution Approach 1:
The control device checks whether the shift lever has returned to the home position before permitting unlock processing after charge connector removal. This preliminary verification prevents unintended unlocking while maintaining ease of operation when the lever is properly positioned.
Solution Approach 2:
The system continuously monitors the shift lever position and provides feedback to the control unit. The control unit uses this feedback to determine whether unlock processing should be permitted, ensuring reliable parking lock control based on actual lever position rather than assuming correct positioning.
2Productivity
If the shift lever is used without position verification, then the unlocking operation is simple and quick, but the vehicle may unlock unintentionally when the lever is held in drive position by external objects
Solution Approach 1:
Before executing the unlock operation, the control device performs a preliminary check to verify that the shift lever has returned to the home position. This additional verification step ensures accurate detection of unlock conditions while maintaining operational efficiency through automated control.
Solution Approach 2:
The system replaces manual verification of shift lever position with an automated detection mechanism. The control unit electronically monitors lever position and automatically determines whether unlock conditions are met, improving both accuracy and speed of the unlocking operation.
Data Source
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AI summary
When a charge connector has been removed from a vehicle-side connector (YES in S102) while parking lock is set (YES in S 100), an ECU determines whether or not there is return history that a momentary shift lever has moved to a home position after removal of the charge connector from the vehicle-side connector (S 104). When there is return history (YES in S104) and when a brake-on state is set, the shift lever has been operated from the home position to any position ofN, D and R, and the resultant position is continuously maintained for a prescribed period of time (YES in S 106), the ECU unlocks the parking lock (S108).