Active Hinge Latching Mechanism for Pedestrian Protection Hood
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Solution Overview
Problem
Conventional active hinges for deployable hood assemblies in pedestrian protection systems face challenges in maintaining the hood in its deployed position effectively, particularly due to the limitations of pyrotechnic actuators and the need for controlled venting, which are not always reliable or efficient.
Innovation Solution
An active hinge with a latching mechanism comprising a primary latch for the non-deployed state and a secondary latch for the deployed state, along with an actuator to release the primary latch, allowing the hood to pivot into the deployed position and be maintained there by the secondary latch, and a reset function to return to the non-deployed state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pyrotechnic actuator is used to hold the hood in its deployed position, then the hood can be maintained in the deployed state, but the system requires controlled venting and becomes less reliable
Solution Approach 1:
The latching mechanism is divided into two separate latches: a primary latch that engages with a primary latch surface to hold the hood in the non-deployed position, and a secondary latch that engages with a secondary latch surface to hold the hood in the deployed position. This segmentation eliminates the need for complex pyrotechnic actuators with venting systems, improving reliability while reducing device complexity.
Solution Approach 2:
The patent introduces a latch mechanism as an intermediary component between the actuator and the hood positioning system. The latch mechanism translates the simple linear motion of the actuator into reliable positional control through engagement with latch surfaces, eliminating the need for complex force control or venting systems.
2Device complexity
If a single latch system is used for both non-deployed and deployed positions, then the device complexity is reduced, but the reliability of maintaining both positions is compromised
Solution Approach 1:
The latching system is segmented into two independent latch mechanisms: a primary latch for the non-deployed position and a secondary latch for the deployed position. Each latch independently engages with its corresponding latch surface, ensuring reliable position maintenance without requiring a complex single-system solution.
Solution Approach 2:
The patent incorporates biasing springs that pre-load the latch mechanisms to ensure positive engagement with the latch surfaces. The first biasing spring maintains engagement between the primary latch and primary latch surface, while the second biasing spring maintains engagement between the secondary latch and secondary latch surface, providing beforehand cushioning against positional instability.
Data Source
AI summary
An active hinge for a deployable hood assembly of the type used in a pedestrian protection system for motor vehicles. The active hinge employs a primary latch to mechanically hold the hinge in a non-deployed condition and a secondary latch to mechanically hold the hinge in a deployed condition.