Shift-by-wire Selector Control System with Electronic Locking
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Solution Overview
Problem
A shift-by-wire selector in motor vehicle transmissions can inadvertently be moved from a non-drive mode to a drive mode due to vibrations or unintentional actions, leading to unsafe vehicle conditions since it lacks a lock mechanism that can only be engaged when in a nominal Park or Neutral position.
Innovation Solution
A system with an electronic transmission selector, indexing mechanism, and warning device that monitors the selector's position, provides a warning if it's in an intermediate position, and inhibits gear changes until it's moved to a safe position, using a locking device that disengages only when the foot brake is depressed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shift-by-wire selector is used without a mechanical lock mechanism, then the ease of operation is improved, but the reliability deteriorates because the selector can be inadvertently moved between positions due to vibrations or unintentional actions
Solution Approach 1:
The patent replaces the traditional mechanical lock mechanism with an electronic control system. The TCU monitors selector position electronically and uses solenoids to engage park and neutral locks only when appropriate conditions are met, eliminating the need for a continuous mechanical lock while maintaining safety through electronic control and conditional mechanical engagement.
Solution Approach 2:
The system implements continuous feedback by monitoring selector position through sensors and comparing it against desired positions. The TCU receives real-time position information and adjusts control signals accordingly, enabling the system to detect intermediate positions and prevent unintended gear changes through active monitoring and response.
2Reliability
If a lock mechanism is added to prevent unintended selector movement, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent makes the lock mechanism dynamic and conditional rather than static and continuous. The park lock and neutral lock are engaged only under specific conditions (park lock when selector is in Park position, neutral lock when selector is in Neutral position), allowing the system to simplify its mechanical state when locking is not required while maintaining reliability when needed.
Solution Approach 2:
The locking function is segmented into separate, independent lock mechanisms for different positions (park lock for Park position, neutral lock for Neutral position). This segmentation allows each lock to be controlled independently based on specific conditions, reducing the complexity of a single universal lock mechanism while improving reliability for each specific position.
3Ease of operation
If the selector can be moved to intermediate positions, then the ease of operation is improved, but the safety deteriorates because drive mode may be selected unintentionally
Solution Approach 1:
The system applies preliminary anti-action by implementing preventive control logic that blocks unintended gear changes before they can occur. When the selector is detected in an intermediate position between Park/Neutral and Drive/Reverse, the TCU prevents the transmission from engaging drive mode, thereby counteracting the potential harmful effect before it manifests.
Solution Approach 2:
The TCU acts as an intermediary between the selector and the transmission control. It receives position information from the selector, evaluates whether the position is valid and safe, and only then transmits appropriate control signals to the transmission. This intermediary function filters out unsafe intermediate positions and prevents them from causing harmful effects.
Data Source
AI summary
A method for operating a multi-stable shift-by wire selector control system of a motor vehicle transmission. The multi-stable shift-by wire selector control system includes a multi-stable selector which is operable by the driver of the vehicle to select a respective one of the operating modes of the transmission, an arrangement of illuminated labels indicating the selector mode and an indexing mechanism for maintaining the immobilization of the selector in its different positions.