Memory Lever for Vehicle Latch Ajar Sensing
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Solution Overview
Problem
Current motor vehicle compartment closure latch systems often experience false-positive 'ajar' status warnings, leading to reduced reliability and increased packaging space requirements, especially in multi-latch tailgate and liftgate systems.
Innovation Solution
The introduction of a memory lever with ajar switch status-retention features that engages a detent lever to hold it lifted when the forkbolt is disengaged, ensuring accurate latching and unlatching status indication through an electronic signal, reducing false-positive warnings and minimizing packaging space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional latch mechanisms are used without memory lever, then the structure is simpler, but false-positive ajar status warnings occur and reliability is reduced
Solution Approach 1:
The memory lever acts as an intermediary component between the detent lever and the ajar switch. It engages with the detent lever to hold it in the switched position temporarily, ensuring the ajar switch accurately reflects the true latch status and preventing false-positive warnings while maintaining reasonable structural complexity
Solution Approach 2:
The memory lever is spring-biased to automatically engage with the detent lever when the forkbolt moves away from the latched position. This preliminary engagement action ensures the detent lever is held in the correct position for accurate switch sensing before the latch mechanism completes its transition
2Reliability
If larger latch mechanism packaging is used to eliminate false positives, then reliability improves, but available packaging space is increased
Solution Approach 1:
The memory lever is designed to nest within the existing latch mechanism structure, engaging with the detent lever in a compact arrangement. This nested configuration provides robust ajar switch sensing without significantly increasing the overall footprint of the latch mechanism
Solution Approach 2:
The memory lever utilizes vertical space by engaging with the detent lever in a vertical dimension rather than expanding the horizontal footprint. The spring-biased engagement allows the memory lever to move vertically to hold the detent lever, maintaining a reduced footprint while improving sensing accuracy
3Length of moving object
If reduced packaging space is used for latch mechanism, then vehicle width is reduced, but lamp assembly size is constrained
Solution Approach 1:
The latch mechanism is segmented into distinct functional components (forkbolt, detent lever, memory lever, spring) that can be compactly arranged. This segmentation allows the mechanism to occupy reduced space while maintaining functionality, thereby preserving vehicle width and allowing for larger lamp assemblies
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
The solution provides robust ajar switch sensing, reducing false-positive warnings and maintaining a reduced footprint, allowing for larger lamp assemblies without increasing vehicle width or compromising gate opening.
Implementation Method 1
The memory lever, which is spring-biased against the detent
Data Source
AI summary
Latch mechanisms for vehicle compartment closure assemblies, methods for making or using such latch mechanisms, and motor vehicles with a latch system for sensing latching/unlatching of a closure assembly are presented. A latch mechanism includes a forkbolt that attaches to the vehicle body and moves between a latched position, engaging a striker and thereby latching a compartment closure assembly in a closed position, and an unlatched position, disengaging the striker. A detent lever attaches to the vehicle body adjacent the forkbolt and moves between a locked position, locking the forkbolt in the latched position, and an unlocked position, disengaging the forkbolt. A memory lever adjacent the forkbolt moves between a catching position, retaining the detent lever in the unlocked position, and a releasing position, disengaging the detent lever. The forkbolt, when moving from the unlatched to the latched position, moves the memory lever from the catching to the releasing position.