Transmission Shifter Assembly with Retainer-Based Shift Lockout
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Solution Overview
Problem
Existing gear shift systems, particularly in shift-by-wire systems, lack effective mechanisms to prevent unintended transmission shifts without user intervention, such as shifting out of park without depressing the brake or other prerequisite actions.
Innovation Solution
A gear shifter design incorporating a retainer and actuator system that selectively prevents rotation of shift bodies based on predefined conditions, using a biasing member and feedback surfaces to manage rotation and provide variable resistance, allowing controlled gear shifts only when specific criteria are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shift-by-wire system is used without a cable connection, then the operator can control the transmission remotely, but the system lacks mechanical prevention against unintended shifts
Solution Approach 1:
A retainer component is introduced as an intermediary mechanical element between the operator's shift lever and the transmission actuator. The retainer can physically block the shift mechanism, preventing unintended gear changes even though the system is otherwise electronically controlled. This mediator provides the missing mechanical safety layer in the shift-by-wire system.
2Reliability
If the retainer prevents rotation of the second body, then unintended shifts are blocked, but the driver cannot shift gears when needed
Solution Approach 1:
The system requires the driver to perform a preliminary action (depressing the brake pedal) before the retainer releases to allow gear shifting. This preliminary action ensures the driver intends to shift gears deliberately. The brake pedal depression triggers the retainer release mechanism, transitioning the system from locked to unlocked state.
3Reliability
If a retainer mechanism is added to prevent unintended shifts, then safety is improved, but the device complexity increases
Solution Approach 1:
The retainer mechanism is integrated with the existing shift lever assembly and transmission control components. The retainer, actuator, and associated linkages are combined into a unified structure that works within the existing shift-by-wire architecture. This merging approach adds safety functionality while minimizing the increase in overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures secure and controlled gear shifts by preventing unintended transmission shifts until necessary driver actions are taken, enhancing safety and operational reliability.
Implementation Method 1
the second actuator is a biasing member having a first part engaged with the first body and a second part engaged with the second body
Data Source
AI summary
At least some implementations of a transmission gear shifter include a first body rotatable among multiple positions, a second body rotatable among multiple positions, a retainer and first and second actuators. The retainer is movable relative to the second body between a first position in which the retainer prevents rotation of the second body, and a second position in which the retainer permits rotation of the second body. The first actuator is coupled to the retainer to move the retainer between the first and second positions. And the second actuator provides a force on the second body to rotate the second body when the retainer is in the second position.