Pedestrian Safe Hood Latch With Stop Lever
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Solution Overview
Problem
Automotive hood latches face challenges in providing the necessary springiness to absorb impact while maintaining a solid closing mechanism and preventing unwanted movement due to road vibrations and wind loads, while also ensuring pedestrian safety in front collisions.
Innovation Solution
A three-position hood latch with an extra long fishmouth and a ratchet-pawl mechanism, combined with a stop lever and release mechanisms, allows the striker to absorb impact forces by retaining it at an intermediate depth in the fishmouth, enabling vertical movement during collisions while maintaining a solid closing action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the hood is rigidly connected to the frame, then the latch provides a solid closing action, but the hood cannot absorb impact forces during pedestrian collisions
Solution Approach 1:
The latch system transitions from a static rigid connection to a dynamic system with three positions (closed, intermediate, and open). The striker can move between these positions depending on the force applied, allowing the hood to remain stable during normal operation but move to absorb impact forces during collisions.
Solution Approach 2:
The fishmouth is divided into multiple zones: a first zone for normal closed position, a second zone for intermediate position, and a third zone for full open position. This segmentation allows the latch to provide different levels of restraint based on the striker's position, enabling both stability and impact absorption.
2Object-affected harmful factors
If the hood is flexibly coupled to absorb impact, then pedestrian safety is improved, but the latch may appear to reciprocate during closing instead of providing a solid action
Solution Approach 1:
The stop lever engages the striker at a specific intermediate position (second zone) rather than allowing full movement. This partial engagement provides enough flexibility for impact absorption while preventing excessive movement that would cause the reciprocating effect during normal closing operations.
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 effectively absorbs impact forces during pedestrian collisions, providing the necessary springiness while maintaining a solid closing action and preventing unwanted hood movement, thus enhancing pedestrian safety and operational reliability.
Implementation Method 1
The stop lever has a proboscis on one of the arms and is biased such that the slot generally aligns with the fishmouth with the proboscis jutting into or otherwise juxtaposed so as to interfere with the fishmouth
Implementation Method 2
A ratchet and pawl combination selectively retain the striker in the fishmouth, the ratchet moving between a closed position wherein the striker is retained in the fishmouth and an open position wherein the striker is free to exit the fishmouth
Implementation Method 3
The ratchet is biased to the open position and the pawl is biased to the closed position
Implementation Method 4
The stop lever is mounted and configured for the proboscis to receive an impact from the striker so as to overcome the bias and rotate the stop lever to a blocking position wherein the non-proboscis arm intercepts the striker
Implementation Method 5
A release mechanism is provided for urging the pawl out of the locking position
Data Source
AI summary
A hood latch having an extra-long fishmouth for enabling a vehicle hood to deflect downwardly upon impact, such as when hit by a pedestrian in a frontal crash. To prevent this deflection when the hood is slammed shut in ordinary use, a stop lever is pivotally mounted to the latch housing. The stop lever features first and second arms defining a slot therein. One arm has a proboscis thereon and is biased to align the slot with the fishmouth, with the proboscis jutting into the fishmouth. The proboscis receives an impact from the striker and rotates the stop lever to a blocking position wherein the non-proboscis arm intercepts the striker and prevents it from reaching the bottom end of the fishmouth. In the closed position the ratchet retains the striker at an intermediate depth in the fishmouth, enabling the striker to travel toward the bottom end thereof.