Pistonless Pneumatic Linear Actuator With External Restoring Element
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Solution Overview
Problem
Conventional pneumatic actuators, particularly double-acting pneumatic cylinders, are complex and expensive, making them unsuitable for cost-effective applications in robot-assisted surface processing, and they struggle with precise force control due to high inertia, which limits their ability to compensate for process force fluctuations.
Innovation Solution
A cost-effective pneumatic linear actuator design without a piston, featuring a first housing with a pressure chamber, a rod sealed by a rod seal, and a restoring element outside the housing to generate an attractive force between mounting plates, allowing gas pressure to propagate throughout the chamber and absorb bending moments, while a smaller actuator regulates process force independently of position control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional double-acting pneumatic cylinders are used, then reliable force control is achieved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent removes the piston from the conventional pneumatic cylinder design, extracting only the essential function of pressure application while eliminating the complex piston-sealer mechanism. Gas pressure acts directly on the rod's end surface, simplifying the internal structure while maintaining force control capability through the relationship F = p × A, where A is the rod's end surface area.
Solution Approach 2:
Instead of using a piston to transmit force from pressure to rod, the design inverts the approach by having the rod itself serve as the pressure reception surface. The rod is inserted into the pressure chamber with its end surface facing the gas pressure, reversing the conventional force transmission path and eliminating the need for a piston.
2Force
If conventional pneumatic actuators are used, then sufficient force is generated, but manufacturing cost increases due to complex structure
Solution Approach 1:
By removing the piston, seals, and complex internal components of conventional actuators, the design reduces manufacturing steps and component count. The housing becomes a simple pressure chamber, and the rod serves dual purposes as both the force transmission element and the pressure reception surface, significantly lowering manufacturing cost.
Solution Approach 2:
The rod performs multiple functions: it transmits force to the load, serves as the pressure reception surface for gas pressure application, and acts as a structural support element. This multi-functionality reduces the number of components needed and simplifies the overall actuator design, making it more cost-effective to manufacture.
3Strength
If conventional actuators with high inertia are used, then structural strength is maintained, but ability to compensate for process force fluctuations decreases
Solution Approach 1:
The patent employs a spring element as a restoring force mechanism that provides dynamic response to force variations. The spring's elastic properties allow it to automatically compensate for process force fluctuations through deformation and recovery, enabling the actuator to adapt quickly to changing load conditions while maintaining structural integrity.
Solution Approach 2:
The design changes the mechanical parameters by using a spring-based restoring force instead of heavy mechanical components for structural support. This reduces the overall inertia of the moving parts while maintaining sufficient structural strength, allowing the actuator to respond more quickly to process force fluctuations and improve productivity in dynamic applications.
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
Enables precise force control and compensation for inaccuracies in workpiece positioning and manipulator trajectory, providing a cost-effective alternative to conventional actuators with improved mechanical decoupling and reduced manufacturing complexity.
Implementation Method 1
a first rod seal arranged around the first rod, which seals the first pressure chamber
Implementation Method 2
a restoring element arranged to counteract a force exerted on the first rod by the gas pressure, the restoring element being located outside the first housing between the first mounting plate and the second mounting plate, and configured to generate an attractive force between the first mounting plate and the second mounting plate
Implementation Method 3
allowing any gas pressure present in the first pressure chamber to propagate throughout the entire first pressure chamber up to the first rod seal
Data Source
Figure 1~2
Figure 3
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AI summary
The invention relates to a pneumatic actuator. According to one embodiment, the actuator has the following: a housing having a pressure chamber; a rod inserted into the pressure chamber of the housing from the outside; a rod seal which is located around the rod and seals the pressure chamber; and a rod guide which is mounted on the housing and is designed to guide the rod along the longitudinal axis thereof. There is no piston arranged in the pressure chamber. Rather, an unsealed annular gap is present inside the pressure chamber between the rod and an inner wall of the pressure chamber, so that a gas pressure prevailing in the pressure chamber can propagate in the entire pressure chamber as far as the rod seal.