Hood Lifting Actuator Locking Ring to Prevent Impact Retraction
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Solution Overview
Problem
Existing hood lifting actuators in motor vehicles tend to retract when subjected to forces from pedestrian impacts, necessitating a low-cost, easy-to-manufacture solution to maintain the hood in an elevated position.
Innovation Solution
A hood lifting actuator with a housing, piston, and locking ring mechanism that prevents retraction by engaging the piston's transition portion and protrusion when a force is applied, ensuring the hood remains elevated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hood lifting actuator is used to lift the hood portion, then the hood can be elevated in a pedestrian collision situation, but the actuator may retract when forces from impact are applied
Solution Approach 1:
The actuator is segmented into distinct functional components: a housing, a piston, and a locking ring. The locking ring is a separate element that can be independently installed and functions as a distinct locking mechanism, allowing the actuator to be assembled from modular parts rather than a monolithic structure.
Solution Approach 2:
The locking ring is pre-installed in the housing at a position that corresponds to the extended position of the piston. This preliminary positioning ensures that when the piston extends, the locking ring is already in place to engage with the piston's external shoulder, automatically preventing retraction without requiring additional control mechanisms.
2Reliability
If a locking mechanism is added to prevent retraction, then the hood remains elevated during impact, but the manufacturing complexity and cost increase
Solution Approach 1:
The locking ring features a localized engagement geometry with an internal shoulder that matches the external shoulder on the piston. This localized quality ensures that the locking function is achieved through a specific geometric feature rather than a complex mechanism, simplifying manufacturing while maintaining reliability.
Solution Approach 2:
The locking ring is designed to be self-retaining within the housing, utilizing the housing's internal geometry to hold the locking ring in place. The locking ring automatically engages with the piston when the piston extends, requiring no additional actuators, sensors, or control systems to activate the locking function.
3Ease of operation
If the locking ring engages the piston's wide portion, then the piston is locked in the retracted position, but the piston cannot extend
Solution Approach 1:
The locking ring's engagement state is dynamic rather than fixed. When the piston is retracted, the locking ring engages the wide portion to prevent unintended movement. When the piston extends under actuation forces, the locking ring transitions to engage the external shoulder, allowing the piston to reach and maintain the extended position. This dynamic behavior eliminates the need for multiple locking mechanisms.
Solution Approach 2:
The locking mechanism utilizes radial dimension changes in the piston rod (wide portion versus narrow portion with external shoulder) to control the locking ring's engagement. By varying the radial dimension at different axial positions of the piston, the mechanism achieves different locking states without increasing axial complexity.
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 actuator effectively locks the piston in an extended position, maintaining the hood elevated during and after impact, thereby preventing unintended retraction and ensuring safety.
Implementation Method 1
A gas generator is coupled to the proximal end
Data Source
AI summary
A hood lifting actuator according to various implementations includes a piston, a locking ring, and a housing including a protrusion. The housing further includes a distal end, the distal end defining a distal end wall, wherein the locking ring is retained between the distal end wall and the protrusion prior to actuation of the actuator. The piston travels from a retracted position to an extended position. In the extended position, the hood lifting actuator lifts a portion of a vehicle hood into an elevated position. In response to a force urging the piston from the extended position toward the retracted position, such as a person impacting the portion of the vehicle hood, the locking ring engages the protrusion and the piston, thereby locking the piston in a locked position.