Resettable Inertia Lock Assembly for Vehicle Access Closures
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Solution Overview
Problem
Motor vehicle access closure latch assemblies are prone to unintended opening during impact events due to acceleration forces causing the release handle to inadvertently actuate the latch mechanism, leading to potential safety issues.
Innovation Solution
A resettable inertia lock assembly is mounted within the access closure, featuring a chassis, cassette, and a resettable locking apparatus with an inertia-activated member and engagement coupler that secures the member in an inertia-activated position to prevent unlatching, and can be manually reset to its home position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inertia lock assembly is added to prevent unintended opening during impact, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The inertia lock assembly is nested within the existing latch assembly structure. The inertia lock member integrates with the bellcrank mechanism, and the engagement coupler is housed within the latch assembly housing, allowing the safety function to be incorporated without adding a completely separate external system.
Solution Approach 2:
The inertia lock functionality is merged with the existing bellcrank and latch mechanisms. The inertia lock member combines the inertia-based safety activation with the bellcrank's unlatching function, while the engagement coupler merges the locking function with the existing latch structure, reducing overall system complexity.
2Reliability
If the engagement coupler is designed to secure the inertia-activated member firmly, then reliability is improved, but ease of operation deteriorates due to difficulty in manual resetting
Solution Approach 1:
The engagement coupler employs a dynamic ramp structure that changes its engagement characteristics based on the direction of force applied. During normal operation, the ramp provides strong engagement security. During resetting, the ramp geometry allows controlled disengagement when force is applied in the reset direction, enabling easy manual resetting while maintaining secure locking during normal use.
Solution Approach 2:
The ramp structure acts as an intermediary between the engagement coupler and the inertia-activated member. The ramp mediates the interaction by providing a geometric transformation that converts strong engagement forces during normal operation into controlled disengagement during resetting, resolving the contradiction between security and ease of operation.
3Reliability
If the inertia-activated member is made highly responsive to acceleration forces, then the locking function is improved, but false activation from normal vehicle vibrations may occur
Solution Approach 1:
The inertia lock member is designed with specific mass and moment of inertia parameters that are tuned to respond to high-g impact forces while remaining insensitive to low-g vibrations. The engagement coupler's ramp geometry is also designed with specific angular parameters that require a threshold acceleration force to initiate engagement, filtering out false activations from normal vehicle vibrations while maintaining responsiveness to genuine impact events.
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 inertia lock assembly effectively prevents unintended opening of the access closure during impact events by blocking the bellcrank's rotation to the unlatching position until manually reset, ensuring safety and reliability.
Implementation Method 1
an inertia-activated member responsive to an acceleration force to move from a home position to an inertia-activated position
Data Source
AI summary
A resettable inertia lock assembly may include a chassis configured to be mounted within an access closure of a motor vehicle, a cassette, a reset structure defined on one of the chassis and the cassette, a resettable locking apparatus carried by the cassette and including an inertia-activated member and an engagement coupler, the engagement coupler movable between a first position securing the inertia-activated member in an inertia-activated position and a second position in which the engagement coupler does not secure the inertia-activated member in the inertia-activated position, and a movement device for producing a relative movement between the chassis and the cassette to cause the reset structure to engage and move the engagement coupler from the first position to the second position thereof to allow the inertia-activated member to move from the inertia-activated position to a home position.