Vehicle Latch Overslam Stop Feature for Pedestrian Protection
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Solution Overview
Problem
Vehicle hood latches face mechanical limitations in providing sufficient lift for pedestrian protection systems, requiring automatic reset after over slam conditions and normal operation without utilizing extra travel.
Innovation Solution
A latch system with a ratchet, pawl, and levers that adjust travel based on predefined speed thresholds, inhibiting or facilitating striker movement into an over slam region, utilizing a biasing member to control the rotation of the ratchet and levers for automatic reset and normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the latch is designed to provide greater striker travel for pedestrian protection, then hood lift capability is improved, but the latch becomes vulnerable to over slam damage during normal operation
Solution Approach 1:
The latch channel is designed with two distinct regions: a first region with normal wall spacing for standard operation, and a second region (over slam region) with different wall spacing for pedestrian protection. The striker can dynamically access either region based on the impact conditions, allowing the system to adapt its travel distance rather than being fixed at one configuration.
Solution Approach 2:
Different portions of the latch channel have different structural properties. The first region has walls spaced to provide normal operational restraint, while the second region has walls spaced to allow greater travel for pedestrian protection. This local differentiation allows each region to optimize for its specific function without compromising the other.
2Object-affected harmful factors
If the latch allows extra striker travel for active pedestrian protection, then pedestrian safety is improved, but normal latch operation becomes inefficient with unnecessary extra travel
Solution Approach 1:
The system dynamically adapts its behavior based on impact conditions. During normal operation, the striker is restrained within the first region, providing efficient latching without unnecessary travel. During pedestrian impact, the system allows the striker to access the second region, providing the needed protection. The transition between these states is automatic and condition-dependent.
3Ease of manufacture
If the latch structure is simplified for mass and packaging, then manufacturing cost is reduced, but the ability to provide sufficient lift for pedestrian protection is compromised
Solution Approach 1:
The latch channel is segmented into distinct functional regions: a first region for normal operation and a second region for pedestrian protection. This segmentation allows the structure to provide extended travel capability without requiring a complete redesign of the entire latch, maintaining manufacturing simplicity while achieving the needed lift capability through strategic use of space.
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
Enables greater hood lift during pedestrian impacts while preventing unnecessary extra travel during normal operation, ensuring safety and efficient operation.
Implementation Method 1
a pair of levers biased towards a rest position by a biasing member coupled to at least one of the pair of levers
Data Source
AI summary
A latch for a closure panel of a vehicle including a latch housing; a ratchet mounted to the latch housing and movable between a closed position and an open position, the ratchet having a channel for receiving a striker with a first portion relative to the channel and a second portion relative to the channel, the channel having an over slam region positioned adjacent to a bottom of the channel; a pawl mounted to the latch housing and movable between a ratchet holding position and a ratchet release position; and a pair of levers mounted to the latch housing and configured for corotation about a pivot, the pair of levers biased towards a rest position by a biasing member coupled to at least one of the pair of levers.