Vehicle Latch Device Stabilizing Striker Position via Curved Engaging Groove
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Solution Overview
Problem
Conventional latch devices for vehicle backrests experience unstable striker movement and fluctuating strength due to varying impact forces, leading to potential instability and noise issues during vehicle deceleration or collisions.
Innovation Solution
A latch device with a rotatably supported latch, ratchet, and cam member that securely engages and restrains a striker between a deep side wall and an engaging groove, with a narrowing distance between these components in the meshed position to stabilize the striker's position and absorb impact forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the restraint surface Fc projects upward in the conventional latch device, then the striker can be restrained by the wall surface Fb and restraint surface Fc, but the striker moves to various positions in the hook groove Sf by applied impact force and its moving direction becomes unstable
Solution Approach 1:
The engaging groove is formed with a curved surface that becomes narrower toward the inlet side, creating a wedge-shaped configuration. This curved geometry guides the striker to a specific position and prevents lateral movement, thereby stabilizing the striker position without requiring additional complex components.
Solution Approach 2:
The distance between the deep side wall and engaging groove is locally varied along the engaging groove, being narrower at the inlet side and wider toward the deep side. This local variation in geometry creates a self-centering effect that stabilizes the striker position while maintaining structural simplicity.
2Strength
If the wall surface Fb and restraint surface Fc are inclined at angles θ2 and θ3, then the striker is restrained at a stable position, but the strength of the latch device fluctuates depending on the distance between the hook F and striker St
Solution Approach 1:
The curved engaging groove with narrowing inlet geometry ensures that the striker is guided to a unique, well-defined position where it contacts both the deep side wall and the engaging groove. This geometric constraint eliminates position variability, ensuring consistent strength regardless of impact force variations.
3Object-affected harmful factors
If the latch device uses a conventional hook groove configuration, then the structure is simple, but noises are generated when the striker collides against the base groove by vibration
Solution Approach 1:
The narrowing geometry of the engaging groove converts the potential harmful collision between striker and base groove into a beneficial self-centering mechanism. The wedge-shaped configuration guides the striker to engage properly with the latch, transforming impact energy into positioning precision and reducing noise.
Data Source
AI summary
A latch device includes a base member that has an entering groove having a deep side wall, a latch including an engaging groove having a restraining wall, and a ratchet that meshes with the latch in a meshed position. The latch device further includes a cam member that rotates the latch to a restrained position. In the restrained position, the cam member abuts against the latch to nip a striker between the deep side wall and the restraining wall. The restraining wall includes an inclined surface approaching the deep side wall toward an inlet side of the engaging groove at least in the meshed position.