Double Pawl Vehicular Latch with Secure Lock Lever
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Solution Overview
Problem
Double pawl arrangements in vehicular latches face issues with unintended release due to unbalanced forces, particularly in crash situations, and degradation of biasing means over time, leading to insufficient locking mechanisms.
Innovation Solution
A vehicular latch design incorporating a ratchet, primary pawl, auxiliary ratchet, and secondary pawl, along with a secure lock lever, utilizes a drive mechanism and gear wheel to prevent premature opening and ensure reliable locking, using a combination of biases and mechanical interactions to manage pawl positions and forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a double pawl arrangement is used to reduce release effort, then the latch can be opened with relatively low effort, but unbalanced forces may unintentionally release the latch in crash situations
Solution Approach 1:
The latch is divided into two independent pawl-ratchet sets (first and second pawls with respective ratchets) that operate in parallel. Each set provides independent locking, so that the failure or unintended release of one does not necessarily cause complete latch failure. This segmentation allows the system to maintain high reliability while keeping individual release efforts low.
Solution Approach 2:
Two pawl-ratchet mechanisms are combined into a single latch assembly where both must be simultaneously overcome for release. The force application points are positioned to create opposing moments that balance each other, requiring a coordinated force application rather than allowing unintended release from unbalanced forces alone.
2Stability of the object's composition
If biasing means such as springs are employed to reset pawls to locked positions, then the pawls return to locked positions, but over time these biasing forces may degrade or become insufficient
Solution Approach 1:
The latch mechanism is designed so that the normal operation of the latch itself serves to reset the pawls. When the latch is closed, the movement of the door or panel automatically drives the pawls into their locked positions through mechanical guidance and forcing surfaces, eliminating dependence on degrading spring forces for the reset function.
Solution Approach 2:
The pawls are pre-positioned in their locked positions through mechanical constraints and guiding surfaces that ensure proper alignment before engagement. The closing motion of the door performs the reset action in advance, ensuring pawls are ready for locking without requiring active biasing during the critical locking moment.
3Ease of operation
If a double pawl arrangement is used, then release effort is reduced, but the device complexity increases
Solution Approach 1:
The second pawl-ratchet assembly is nested within or integrated with the first pawl-ratchet assembly, sharing common mounting structures, housing elements, and force transmission paths. This nested arrangement allows two independent locking functions to coexist in a compact form factor, reducing the overall complexity compared to two separate latch mechanisms.
Solution Approach 2:
Common structural elements serve multiple functions: the housing provides mounting for both pawls, force application points serve both locking and resetting functions, and the ratchet teeth designs are standardized across both sets. This multi-functionality reduces the total number of unique components and simplifies manufacturing.
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 design reduces the effort required to open and close the latch while preventing unintended releases and ensuring reliable locking, even under varying conditions, including crashes, by sequencing the movement of the secure lock lever and secondary pawl through the drive mechanism.
Implementation Method 1
the ratchet being biased towards the striker release position
Implementation Method 2
the primary pawl being biased towards the ratchet checking position
Implementation Method 3
the secondary pawl being biased to the auxiliary ratchet holding position
Implementation Method 4
the secure lock lever being biased to the locking position
Data Source
AI summary
A low release effort eccentric double pawl vehicle latch includes a ratchet, primary pawl, auxiliary ratchet and secondary pawl in combination with a secure lock lever. The secure lock lever selectively inhibits movement of the secondary pawl to prevent premature or unintended opening of the latch. A drive mechanism sequences movement of the secure lock lever and secondary pawl to open the latch. Upon reset, the drive mechanism drives the auxiliary ratchet back to its closed state and in the process the auxiliary ratchet can engage and return the secondary pawl back to a closed state in the event of an insufficient bias force thereon.