Momentary Shift Operator Control for Neutral Range Torque Drop Prevention
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Solution Overview
Problem
In vehicles using shift-by-wire systems with momentary-type operators, there is a risk of torque drop due to unintended changes into a neutral range when the operator is held at the neutral position for a predetermined time, leading to driver intention mismatch and reduced ride comfort.
Innovation Solution
A control system that includes an automatic transmission, a momentary-type operation device, and an electronic control unit, which changes the shift range based on the initial position, neutral operation position, and traveling operation positions, prohibiting changes to the neutral range when the operator passes through traveling positions, even if held for a predetermined time, and enabling neutral range changes only when intended by the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the operator is held at the neutral operation position for a predetermined time or longer, then the shift range is changed to the neutral range, but this causes torque drop and driver intention mismatch
Solution Approach 1:
The system dynamically adjusts the neutral range shift control strategy based on the operator's movement history. When the operator passes through traveling operation positions during the operation, the control unit prohibits shift range change to neutral range even if held for predetermined time. This dynamic adaptation prevents torque drop while maintaining reliable neutral range selection when truly intended.
Solution Approach 2:
The control unit monitors and records the operator's movement path through various operation positions. By analyzing whether the operator passed through traveling positions (R or D) during the operation, the system provides feedback to determine whether to allow or prohibit neutral range shift, thereby preventing unintended torque drops.
2Adaptability or versatility
If the operator passes through traveling operation positions during operation, then the system should recognize driver intention to travel, but the conventional system still changes to neutral range causing torque drop
Solution Approach 1:
The control system dynamically adjusts its behavior based on detected operator movement patterns. When traveling operation positions are detected during the operation sequence, the system adapts by prohibiting neutral range shift, thereby recognizing driver intention to travel and preventing harmful torque drops.
Solution Approach 2:
The control unit uses feedback from position sensors to track whether the operator passed through traveling positions. This information feeds into the decision logic that prohibits neutral range shift when traveling intention is detected, improving adaptability to driver intent.
3Measurement precision
If the shift range is changed to neutral range during operator movement, then the neutral operation position is properly registered, but ride comfort is reduced due to torque drop
Solution Approach 1:
The system dynamically controls the timing and condition of neutral range shift based on operator movement characteristics. By prohibiting neutral shift when traveling positions are detected, the system maintains operation position detection accuracy while preventing ride comfort degradation from unintended torque drops.
Data Source
AI summary
An operator is a momentary operator. An electronic control unit is configured to when the operator does not pass through any one of traveling operation positions while the operator is operated from an initial position to an neutral operation position and then returned to the initial position, and when the operator is continuously held at the neutral operation position for a first predetermined time or longer, change a shift range of an automatic transmission to the neutral range, and when the operator passes through at least one of the traveling operation positions while the operator is operated from the initial position to the neutral operation position and then returned to the initial position, prohibit a change of the shift range to the neutral range even when the operator is continuously held at the neutral operation position for the first predetermined time or longer.