Vented Linear Actuator Radial Channel Depressurization
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Solution Overview
Problem
Pyrotechnic linear actuators face challenges in achieving specified de-pressurization time frames and force targets for returning to their pre-deployed position, especially in retaining gas pressure and avoiding excessive force that could cause injury.
Innovation Solution
A vented linear actuator design featuring a piston and piston rod with a radial channel that allows controlled depressurization by venting pressurized gas through a radial channel, enabling tunable de-pressurization and force management to meet manufacturer specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the actuator retains gas pressure to maintain force, then the force is sufficient to move the vehicle part, but the de-pressurization time frame and force targets cannot be achieved
Solution Approach 1:
The patent applies dynamics by making the vent channel configurable to change the actuator's behavior. The vent channel can be adjusted or removed to dynamically control the de-pressurization rate, allowing the actuator to meet both force requirements during operation and de-pressurization time frame requirements when resetting, thereby resolving the contradiction between maintaining force and achieving timely de-pressurization.
Solution Approach 2:
The patent changes the parameter of gas flow restriction by providing a configurable vent channel with adjustable dimensions. By modifying the vent channel's size, shape, or presence, the gas flow rate during de-pressurization is controlled, enabling the actuator to achieve specified de-pressurization time frames and force targets that would otherwise be impossible with a fixed-pressure retention design.
2Force
If the actuator retains gas pressure to maintain force, then the actuator can perform its function, but excessive force may cause injury to pedestrian
Solution Approach 1:
The configurable vent channel enables dynamic control of the actuator's force characteristics. During normal operation, the vent channel can be configured to maintain sufficient force for moving vehicle parts. During reset or emergency conditions, the vent channel allows controlled de-pressurization to reduce force to safe levels, preventing pedestrian injury while maintaining functional performance.
Solution Approach 2:
By adjusting the vent channel parameters (size, shape, configuration), the actuator's force output can be tuned to meet both performance requirements and safety targets. The vent channel provides a mechanism to change the gas pressure parameters, enabling force reduction to below 200 Newtons when needed, thereby eliminating the harmful effect of excessive force on pedestrians.
3Duration of action of moving object
If the actuator is designed to meet de-pressurization time frame, then safety is improved, but the actuator cannot achieve specified force targets
Solution Approach 1:
The configurable vent channel provides dynamic control over the actuator's pressure-decay characteristics. The vent channel can be optimized for rapid de-pressurization to meet de-pressurization time frame specifications, while the actuator's force generation capability is maintained through proper sizing and configuration of the vent channel that allows sufficient force during operation but enables quick pressure release when needed.
Solution Approach 2:
The vent channel's geometric parameters are designed to achieve the specified de-pressurization time frame (e.g., within 2 seconds) while maintaining force targets. By carefully selecting the vent channel's cross-sectional area, length, and shape, the gas flow rate during de-pressurization is controlled to meet the time frame requirement, and the same vent channel configuration ensures the actuator can generate the required force during normal operation.
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 solution allows for controlled depressurization and force reduction, enabling the actuator to return to its initial position within specified times and forces, reducing the risk of injury by managing gas pressure effectively.
Implementation Method 1
The radial channel is in fluid communication with the cavity of the piston rod, the opening of the piston, the channel of the housing, and the axial opening to the channel of the housing during at least a portion of an upward stroke of the piston rod through the channel
Data Source
AI summary
Various implementations include a linear actuator that provides controllable depressurization of the actuator and is tunable to the specifications set by the vehicle manufacturer. The linear actuator includes a housing and a piston and piston rod that are slidably disposed within a channel extending through the housing. The piston rod defines a vent path that includes an axial cavity adjacent the proximal end of the piston rod and radial channel extending from the axial cavity to an outer peripheral surface of the piston rod. Pressurized gas entering the housing causes the piston to move axially through the housing, and a portion of the gas vents through the cavity and radial channel to the channel of the housing and then to the environment. This venting allows the actuator to be returned to its initial or stored position within a time frame and without exceeding the force set by the manufacturer.