Shift Lever Neutral Detection Using Variable Passage Time
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Solution Overview
Problem
Existing shift-by-wire range switching devices face challenges in accurately determining the neutral position of a shift lever without causing driver discomfort or erroneous determinations, particularly when the neutral position recognition time is lengthened or shortened due to varying conditions such as temperature.
Innovation Solution
A range switching device that includes a momentary selector lever with a position detector, moving speed acquisition unit, passage time acquisition unit, determination time setting unit, and determination unit, which detects the selector lever's position and moving speed to set an appropriate neutral determination time based on expected passage time, ensuring accurate neutral position selection without discomfort or errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the neutral position recognition time is lengthened to prevent erroneous determination when returning from forward or reverse position, then the reliability of position detection is improved, but the response time when moving from home position to neutral position increases
Solution Approach 1:
The patent applies dynamics by making the neutral position recognition time variable rather than fixed. The control unit dynamically adjusts the recognition time TN based on the shift lever's moving speed: when the lever returns from forward/reverse positions (slower speed), a longer recognition time is used to prevent erroneous detection; when moving from home position (faster speed), a shorter recognition time is used to improve response. This dynamic adjustment resolves the contradiction between reliability and time loss.
Solution Approach 2:
The patent changes the parameter of neutral position recognition time based on the shift lever's moving speed. By measuring the moving speed and using it to determine the appropriate recognition time, the system adapts the detection parameters to match the actual operational context, thereby preventing erroneous determination while maintaining fast response when needed.
2Productivity
If the neutral position recognition time is shortened to improve response when moving from home position, then the productivity of position switching is improved, but the reliability of position detection deteriorates due to erroneous determination
Solution Approach 1:
The system dynamically adjusts the recognition time based on the shift lever's moving speed. When the lever is moving quickly from the home position, the system uses a shorter recognition time TN to enable fast position switching. When the lever returns slowly from forward or reverse positions, the system extends the recognition time to prevent erroneous detection. This dynamic parameter adjustment resolves the contradiction between productivity and reliability.
Solution Approach 2:
The patent changes the detection parameter (recognition time) according to the measured moving speed of the shift lever. By using the moving speed as a basis for parameter selection, the system achieves short recognition times for fast movements (improving productivity) while using longer recognition times for slow movements (maintaining reliability), thus resolving the contradiction.
Data Source
AI summary
A range switching device includes a momentary selector lever movable on a shift gate, a position detector, a moving speed acquisition unit, a passage time acquisition unit, a determination time setting unit, a timing unit, and a determination unit. A neutral position determination region is disposed on a movement path between a home position determination region, a forward travel position determination region, and a reverse travel position determination region. When the selector lever moves from the forward travel position determination region toward the neutral position determination region, the passage time acquisition unit obtains an expected passage time based on a moving speed of the selector lever. The determination time setting unit sets a neutral determination time in accordance with the expected passage time. When the time measured by the timing unit reaches the neutral determination time or longer, the determination unit determines that the neutral position is selected.