Two-Step Latch Assembly with Tertiary Catch for FMVSS Compliance
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Solution Overview
Problem
Current latch assemblies for front trunk compartments in electric and mid/rear-engine vehicles fail to meet Federal Motor Vehicle Safety Standards for two-step release and entrapment regulations, particularly when the vehicle is in motion, and do not ensure secure closure or easy release mechanisms.
Innovation Solution
A latch assembly comprising a forkbolt, detent, and tertiary catch, where the detent engages with the forkbolt in multiple positions and the tertiary catch is biased to rotate, allowing for a two-step release mechanism and secure re-engagement, with an actuator system for controlled operation to meet safety standards and facilitate easy access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional single-step latch mechanism is used, then the device complexity is low, but it fails to meet FMVSS two-step release requirements and safety standards
Solution Approach 1:
The latch mechanism is divided into distinct functional components: a forkbolt with multiple engagement positions, a detent mechanism for two-step release, and a tertiary catch for secondary engagement. This segmentation allows each component to perform its specific function while collectively meeting safety standards without excessive overall complexity.
Solution Approach 2:
The latch system incorporates dynamic elements including a biased forkbolt that can rotate between multiple positions, a detent that engages/disengages based on force applied, and a tertiary catch that provides conditional engagement. These dynamic characteristics enable the system to automatically respond to operational conditions while maintaining safety requirements.
2Reliability
If a secure two-step release mechanism is implemented, then the reliability and safety compliance improve, but the ease of operation decreases due to multiple steps required
Solution Approach 1:
The forkbolt is pre-biased into specific engagement positions, and the detent is pre-positioned to engage with the forkbolt at predetermined locations. This preliminary arrangement ensures that when force is applied during operation, the system automatically progresses through the two-step release sequence without requiring complex user manipulation.
Solution Approach 2:
The latch mechanism uses spring biasing and geometric constraints to automatically guide the forkbolt and detent through their engagement and disengagement sequences. The system serves itself by using the applied force to naturally progress through the release steps, reducing the operational burden on the user while maintaining secure closure.
3Reliability
If the latch assembly prevents accidental opening during vehicle motion, then the safety improves, but the ease of access to the compartment decreases
Solution Approach 1:
The tertiary catch is positioned and biased to engage with the forkbolt in a way that prevents unintended release during vehicle motion. This preliminary anti-action counteracts forces that might otherwise cause accidental opening, while the geometric design ensures that deliberate release actions still progress smoothly through the two-step sequence.
Solution Approach 2:
The detent acts as an intermediary element between the forkbolt and the release mechanism. It mediates the transition between engaged and disengaged states, providing a controlled two-step release that prevents accidental opening while allowing intentional access when properly actuated.
4Reliability
If multiple engagement positions and a tertiary catch are added, then the reliability and safety compliance improve, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The forkbolt integrates multiple engagement positions and the tertiary catch into a single rotating component, reducing the total number of separate parts. The detent mechanism is combined with the forkbolt assembly, allowing multiple functions (two-step release, multi-position engagement, and tertiary catch operation) to be achieved through coordinated movement of integrated components rather than separate mechanisms.
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 latch assembly ensures compliance with safety standards by providing a secure two-step release mechanism and easy access to the compartment, preventing accidental opening during vehicle motion while ensuring secure closure, thus enhancing safety and usability.
Implementation Method 1
a forkbolt biased to rotate in a first direction about a first pivot point
Implementation Method 2
a detent biased to rotate in a second direction about a second pivot point, the detent configured to engage with the forkbolt in at least two different positions
Implementation Method 3
a tertiary catch biased to rotate in the first direction... rotating the tertiary catch to a position to re-secure the striker and restrain the striker from further movement
Implementation Method 4
a forkbolt biased to rotate... a detent biased to rotate... a tertiary catch biased to rotate
Data Source
AI summary
A latch assembly includes a forkbolt biased to rotate in a first direction about a first pivot point, and a detent biased to rotate in a second direction about a second pivot point, the detent configured to engage with the forkbolt in at least two different positions. The latch assembly further includes a tertiary catch biased to rotate in the first direction. The detent is configured to engage a portion of the tertiary catch and rotate the tertiary catch when the detent is rotated in the first direction.