Pistonless Pneumatic Linear Actuator for Precise Force Control
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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 like robot-assisted surface machining, where precise force control and bending moment absorption are required.
Innovation Solution
A cost-effective pneumatic linear actuator design featuring a housing with a pressure chamber, a rod guided by a rod guide, and a rod seal, eliminating the need for a piston and allowing gas pressure to propagate throughout the chamber, which is more economical and capable of absorbing bending moments.
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
Solution Approach 1:
The patent removes the piston from the pressure chamber, extracting the core component that creates complexity in conventional actuators. The rod itself becomes the force transmission element, eliminating the need for piston-sealer assemblies while maintaining force control functionality through direct pressure application to the rod seal.
Solution Approach 2:
The rod serves multiple functions: it transmits force from gas pressure, provides a mounting surface for the rod seal, and acts as a mechanical interface for the rod guide. This multi-functionality reduces the number of separate components needed while maintaining reliable force control.
2Reliability
If conventional double-acting pneumatic cylinders are used, then force control is maintained, but manufacturing cost increases
Solution Approach 1:
By removing the piston and its associated sealing mechanisms, the patent significantly reduces manufacturing complexity and cost. The simplified structure requires fewer precision-machined parts and assembly steps while maintaining the essential force control function through direct pneumatic pressure on the rod seal.
Solution Approach 2:
The rod seal is designed as a simple, replaceable component that can be manufactured at low cost. This approach allows for easy maintenance and replacement without requiring complex piston assemblies, reducing both initial manufacturing cost and long-term operational costs.
3Force
If a piston is used in the pressure chamber, then force transmission is efficient, but device complexity and cost increase
Solution Approach 1:
The patent eliminates the piston entirely, using the rod and rod seal assembly to directly transmit force from gas pressure. This extraction of the piston component maintains efficient force transmission while dramatically reducing structural complexity.
Solution Approach 2:
The design uses pneumatic pressure acting directly on the rod seal to transmit force, eliminating the need for mechanical piston-sealer interfaces. This pneumatic approach maintains force transmission efficiency while simplifying the mechanical structure.
4Stress or pressure
If a piston with sealing is used, then pressure containment is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent removes the complex piston-sealer assembly and replaces it with a simpler rod seal that contains pressure in the same manner. This extraction maintains pressure containment functionality while significantly reducing manufacturing complexity and cost.
Solution Approach 2:
The rod seal acts as a flexible sealing element that contains pressure without requiring rigid piston structures. This approach achieves effective pressure containment using simpler, more cost-effective sealing technology.
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 design provides precise closed-loop force control and mechanical decoupling, enabling gentle contact with surfaces and compensating for inaccuracies in workpiece positioning and robot trajectory, while being simpler and cheaper to manufacture than conventional actuators.
Implementation Method 1
a rod seal arranged around the rod and sealing the pressure chamber
Implementation Method 2
a gas pressure present in the pressure chamber can propagate throughout the entire pressure chamber up to the rod seal
Data Source
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.