Pedestrian Protection Hinge With Frangible Clip And Spring Hold
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Solution Overview
Problem
Existing pedestrian protection systems for automobiles face challenges in maintaining a raised hood position during a pedestrian impact, as pyrotechnical actuators used to create a crumple zone typically lose pressure after actuation, and smaller engine vehicles require alternative methods to absorb impact without actuators.
Innovation Solution
A pedestrian protection automotive hinge design featuring a first and second hinge portion connected by a member pin, with a release assembly that includes a clip and stop pin to allow movement between closed and opened positions, and a hold assembly using a spring tab and ramp to maintain the hood in an opened position during impact, utilizing an actuator to break the clip and engage the hold surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If pyrotechnical actuators are used to raise the hood during pedestrian impact, then the hood can be raised to create a crumple zone, but the actuators lose pressure after actuation and cannot maintain the hood in the raised position
Solution Approach 1:
The hinge system is divided into two functional segments: the actuator assembly that provides the force to raise the hood, and the hold assembly that maintains the hood in the raised position. This segmentation allows each component to specialize in one function, resolving the contradiction between providing impact force and maintaining position.
Solution Approach 2:
The hold assembly acts as an intermediary mechanism between the actuator and the hood. It receives the mechanical energy from the actuator and converts it into a stable held position using the spring tab and ramp interaction, allowing the actuator to release pressure while the hood remains elevated.
2Force
If the hood is raised during pedestrian impact, then a crumple zone is created to absorb impact, but the release assembly must selectively enable movement only during collision while maintaining normal hinge function
Solution Approach 1:
The release assembly uses a frangible connection that transitions from a rigid locked state during normal operation to a broken state during collision. This dynamic transformation allows the same structure to serve dual purposes: maintaining structural integrity during normal use and enabling controlled movement during impact.
Solution Approach 2:
The frangible connection is designed with a specific strength parameter that is lower than the forces generated during pedestrian impact but higher than normal operating forces. This parameter change allows the connection to remain intact during normal hinge function while breaking selectively during collision events to enable the hold assembly to engage.
3Adaptability or versatility
If smaller displacement engines are used, then the hood can collapse into the engine compartment without actuators, but this approach is limited to vehicles with smaller engines and does not provide sufficient protection for larger engine vehicles
Solution Approach 1:
The hinge assembly with the integrated actuator and hold system is designed to be universally applicable to various vehicle types and engine sizes. The system provides active impact absorption capability that works effectively regardless of engine displacement, making it suitable for both compact and full-size vehicles unlike the passive collapse approach.
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
Effectively raises and maintains the hood in an opened position during a pedestrian impact, enhancing impact absorption and preventing violent hood movement, thereby improving pedestrian safety by creating a controlled deceleration and maintaining angular position.
Implementation Method 1
The spring tab and ramp are configured to slide relative to one another while the second member pivots about the member pin relative to the first member to an opened hood collision position in response to a collision input
Implementation Method 2
The clip has a frangible connection that provides a weakened area configured to break
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
A pedestrian protection automotive hinge includes a release assembly which includes a clip supported at one of the first and second ends and a stop pin supported by the other of the one of first and second members. The stop pin is captured in the clip in the normally closed position and the normally opened position. The stop pin is configured to break the clip in response to a collision input permitting the second member to pivot about a member pin relative to the first member to an opened hood collision position and the stop pin to move to a second end of a slot. An actuator is configured to engage the second member and move the second member upward relative to the first member in response to the collision input and break the clip.