Ignition Shift Lever Interlock with Mid Position Recess
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Solution Overview
Problem
Current ignition and transmission shift lever interlock systems in vehicles fail to disconnect the accessory circuit when the transmission shift lever and shaft are in the neutral position, leading to continuous electrical current draw and battery discharge, while maintaining the integrity of the key removal inhibitor system.
Innovation Solution
The system introduces a mid position in the ignition switch and a recess in the shaft, allowing the inhibitor pin to move into an intermediate position, simulating the lock position and disconnecting the accessory circuit, while preventing key removal by maintaining the inhibitor pin's engagement with the transmission shift lever.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the inhibitor pin is moved into the lock position to disconnect the accessory circuit, then electrical current draw is reduced, but the key removal inhibitor system cannot function properly when the transmission is in neutral position
Solution Approach 1:
The inhibitor pin's travel path is segmented into distinct zones: a first region for key removal inhibition, a second region for accessory circuit disconnection, and a third region that is inaccessible. This segmentation allows the pin to perform multiple functions at different positions along its travel path, resolving the contradiction between energy reduction and system reliability.
Solution Approach 2:
The shaft recess acts as an intermediary structure that guides the inhibitor pin through its travel path. The recess creates the spatial configuration that enables the pin to access different functional regions while maintaining proper engagement with the transmission shift lever, facilitating the transition between key removal inhibition and accessory circuit disconnection modes.
2Ease of operation
If the transmission shift lever and shaft are positioned in neutral position for production line movement, then ease of operation is improved, but the accessory circuit cannot be disconnected causing battery discharge
Solution Approach 1:
The system dynamically adapts its behavior based on transmission position. When the transmission is in neutral position during manufacturing, the inhibitor pin is positioned in the second region to disconnect the accessory circuit. When the transmission is in park position during normal operation, the pin moves to the first region to prevent key removal. This dynamic adaptation resolves the contradiction between operational ease and energy conservation.
Solution Approach 2:
Different functional qualities are assigned to different spatial regions along the inhibitor pin's travel path. The first region provides key removal inhibition quality, the second region provides accessory circuit disconnection quality, and the third region remains inaccessible. This local differentiation allows the system to optimize for either key security or energy conservation depending on the transmission position.
3Reliability
If the inhibitor pin is made stationary relative to shaft rotation to maintain key removal inhibition, then reliability is improved, but the accessory circuit cannot be disconnected when transmission is in neutral position
Solution Approach 1:
The inhibitor pin's functionality is extended from a single-dimensional rotation-only movement to a two-dimensional movement combining rotation and axial translation. The pin can rotate with the shaft to maintain key removal inhibition, while also translating axially along the longitudinal axis to access different functional regions. This dimensional change allows the pin to maintain reliability while gaining adaptability for accessory circuit control.
Data Source
AI summary
The interlock system includes a shaft that defines a longitudinal axis which the shaft rotates about during transmission shift operations. A transmission shift lever is coupled to the shaft, and an inhibitor pin is coupled to the ignition switch by a cable. The inhibitor pin engages the transmission shift lever to prevent shift operations when the ignition switch is in the off position. The inhibitor pin disengages the transmission shift lever when the ignition switch is positioned in the accessory position or a start/run position. The shaft includes a recess into which the inhibitor pin extends when the shaft is in the neutral or drive position to permit disconnection of the accessory circuit by moving the ignition switch to a mid position (between the off position and the accessory position) without placing the shaft in the park position.