Pneumatic Actuator Static Seals Diaphragm Piston
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Solution Overview
Problem
Pneumatic actuators face challenges in high-temperature and cryogenic applications due to friction issues with dynamic seals, which degrade over time, and existing solutions are complex, costly, and difficult to maintain.
Innovation Solution
A pneumatic actuator design that uses a deformable diaphragm and static sealing elements, eliminating the need for dynamic seals and allowing for customizable force and torque application through stackable secondary actuating assemblies, enhancing operational reliability across various temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic seals (O-rings) are used to seal the actuator chamber, then sealing effectiveness is improved, but friction increases and seals become sticky and brittle in high-temperature applications
Solution Approach 1:
The patent removes the dynamic seal (O-ring) from the system entirely. Instead of using a sliding seal between the piston and cylinder wall, the invention employs static seals at the cap interfaces and allows the piston to move freely within the chamber without contact seals, thereby eliminating the friction problem while maintaining sealing effectiveness through alternative means.
Solution Approach 2:
The patent replaces the mechanical dynamic seal system with a different sealing approach using static seals at fixed interfaces (caps) and an open piston design. This substitution eliminates the sliding contact mechanism that causes friction and degradation in high-temperature environments.
2Object-affected harmful factors
If lubricants are used to reduce friction between seals and inner wall, then friction is minimized, but lubricants dry down or are blown away, increasing friction over time
Solution Approach 1:
The patent eliminates the need for lubricants by removing the dynamic seal that generates friction. Without a sliding seal, there is no surface requiring lubrication, and thus no risk of lubricant degradation over time.
Solution Approach 2:
The piston design allows it to move freely without external lubrication, essentially serving itself by eliminating the friction-generating interface that would require maintenance.
3Force
If cam mechanisms, gear-cam and pinion mechanisms, or multiple pistons are used to increase force to the actuated shaft, then force output is improved, but device complexity increases and manufacturing costs rise
Solution Approach 1:
The patent combines multiple pistons into a single integrated actuator assembly that moves a common shaft. The multiple pistons operate in parallel within a unified structure, providing cumulative force to the shaft without requiring complex transmission mechanisms like cams or gears.
Solution Approach 2:
The actuator design allows the same basic piston-cylinder assembly to be replicated and stacked to achieve different force levels, providing a universal building block approach that avoids the need for complex specialized mechanisms for each force requirement.
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 reduces friction, increases the lifespan of the actuator, and allows for easy customization of force and torque, making it suitable for a wide range of applications from cryogenic to high-temperature environments while simplifying maintenance and reducing manufacturing costs.
Implementation Method 1
When pressurized fluid is forced through the main inlet or drawn from the main outlet, the first chamber expands, moving the main piston from the unactuated position to the actuated position
Implementation Method 2
The actuator also comprises a biasing mechanism biasing the piston in the unactuated position
Data Source
AI summary
An actuator for actuating a plunger of a valve is provided. The actuator has an inlet and includes first and second hollow caps. A main actuation assembly is provided between the caps. The main actuation assembly includes a deformable diaphragm; first and second chambers, static sealing elements and a main piston movable between actuated and unactuated positions. A biasing mechanism biases the piston in the unactuated position. When pressurized gas is flown through the inlet and/or drawn from the outlet of the actuator, the first chamber expands, moving the main piston from the unactuated position to the actuated position, an actuating stem connected to the main piston thereby sliding within a channel provided in the bottom cap. Stackable actuating assemblies can also be used between the caps. Using static sealing elements advantageously avoids friction between moving parts.