Air Cylinder Piston Rod Vibration Suppression via Pneumatic Friction
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Solution Overview
Problem
Air pressure cylinders for positioning control face challenges in suppressing slight vibrations of the piston near the target position due to low rigidity and high frictional resistance, leading to inaccurate and costly solutions.
Innovation Solution
A simple device with a friction member in contact with the piston rod and an air cell forming sliding friction to suppress vibrations, utilizing a pair of V-packings for sealing and an air flow path to manage compressed air, effectively reducing piston rod vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positioning control is used without additional mechanisms, then the system remains simple and low-cost, but slight vibrations occur at the target position due to low rigidity and insufficient attenuation
Solution Approach 1:
A friction member is introduced as an intermediary element between the piston rod and the cylinder body. This friction member acts as a mediator that provides controlled frictional force to suppress vibrations without requiring complex active control systems. The friction member is pressed against the piston rod by a pressing member, creating a simple passive damping mechanism that effectively reduces positioning vibrations while maintaining system simplicity
Solution Approach 2:
The pressing member that applies force to the friction member is driven by pneumatic pressure. A pressing air chamber is provided that receives compressed air to generate the pressing force on the friction member. This pneumatic actuation provides a simple and effective way to apply the necessary normal force to create friction-based vibration suppression without complex mechanical spring or hydraulic systems
2Manufacturing precision
If electric viscosity fluid or static pressure bearing is used to control friction, then positioning precision improves, but equipment size increases and manufacturing cost rises
Solution Approach 1:
The friction member is designed as a simple, replaceable component made of friction material that can be easily manufactured and replaced. Instead of using expensive electric viscosity fluid systems or precision static pressure bearings, this invention employs a simple friction block that provides effective vibration suppression at low cost. The friction member can be easily replaced when worn, making it an economical solution for maintaining positioning precision
Solution Approach 2:
The friction characteristics are controlled by changing the pressing force parameter applied to the friction member through pneumatic pressure adjustment. By varying the air pressure in the pressing air chamber, the normal force on the friction member changes, which directly controls the frictional damping force. This simple parameter control replaces complex friction characteristic control systems and achieves effective vibration suppression
3Reliability
If piston packing with large diameter is used, then sealing performance improves, but frictional resistance increases and vibration suppression capability decreases
Solution Approach 1:
The friction control function is segmented from the piston packing sealing function. The piston packing maintains large diameter for good sealing, while a separate friction member with controlled dimensions provides the friction-based vibration suppression. This segmentation allows each component to be optimized for its specific function without compromise - the packing for sealing and the friction member for vibration control
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 effectively suppresses piston vibrations, enabling high-speed and high-accuracy positioning without increasing system complexity or cost, as demonstrated by experimental results showing reduced radial displacement and stable damping forces.
Implementation Method 1
the friction member being in contact with the piston rod is pressed to the piston rod and a sliding friction for suppressing the slight vibration is generated therebetween
Implementation Method 2
an air cell for containing compressed air to be fed to a periphery of the piston rod
Data Source
AI summary
A slight-vibration-suppressing mechanism is attached to a piston rod 6 of an air pressure cylinder that stops the piston at a target position by means of a positioning control. The slight-vibration-suppressing mechanism includes a friction member formed of a pair of sealing members being in contact with the piston rod, and an air cell of compressed air fed to a periphery of the piston rod is formed by means of the friction member. An air flow path to feed and discharge the compressed air to the aforementioned air cell is formed, in which the compressed air generates a sliding friction, which suppresses slight vibration, via the friction member between the piston rod and the aforementioned friction member.