Pneumatic Low-Pass Filter for Gas Spring Vibration Isolation

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Solution Overview

Problem

Gas spring vibration isolation systems experience high gas consumption and inherent noise due to leaking systems and non-laminar gas flow, especially at high pressures, which affects their vibration isolating efficiency and load capacity.

Innovation Solution

Incorporating an additional flow resistance in the gas supply line, comprising a non-adjustable laminar restrictor and an adjustable restrictor, acts as a pneumatic low-pass filter to dampen force noise by ensuring laminar gas flow and compensating for system tolerances, thereby reducing power noise and optimizing gas pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If high pressure is used to support heavy load in small-scale gas bearings, then load capacity is improved, but gas flow becomes non-laminar causing force noise and vibration

Engineering Contradiction:
Improveload capacityVSAvoidforce noise
Core Design Contradiction:
ForceVSObject-generated harmful factors

Solution Approach 1:

A laminar flow restrictor is introduced as an intermediary component in the gas supply line between the gas source and the gas bearing. This restrictor creates a pressure drop that ensures laminar flow conditions in the gas bearing, preventing stall and force noise while maintaining the ability to support heavy loads through high pressure operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the flow regime parameter from turbulent to laminar by introducing the restrictor. This parameter change eliminates the stall phenomenon and associated force noise while maintaining load capacity through appropriate pressure control. The restrictor adjusts the gas flow parameters to achieve stable laminar flow conditions.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If servo valve is used for gas quantity control, then gas volume control is improved, but turbulence in gas flow causes power noise

Engineering Contradiction:
Improvegas volume controlVSAvoidpower noise
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The laminar flow restrictor serves as a mediator between the servo valve and the gas bearing. It dampens the turbulence generated by the servo valve's gas quantity control operations, converting turbulent flow into laminar flow before the gas enters the bearing, thereby eliminating power noise while preserving control functionality.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If additional flow resistance is added to dampen force noise, then vibration isolation is improved, but gas consumption increases

Engineering Contradiction:
Improveforce noiseVSAvoidgas consumption
Core Design Contradiction:
Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The restrictor changes the flow parameters to achieve laminar flow, which has different resistance characteristics than turbulent flow. While there is a pressure drop across the restrictor, the laminar flow regime actually reduces overall gas consumption compared to turbulent flow conditions, as the flow is more efficient and stable.

Inventive Principle:
Principle #35Parameter changes

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 minimizes intrinsic noise and maximizes load capacity while reducing gas consumption by filtering out high-frequency vibrations and maintaining stable gas pressure, enhancing the vibration isolation performance of gas spring systems.

Implementation Method 1

Such a laminar restrictor or a laminar throttle increases the flow resistance and makes the gas flow flowing through it laminar

Methodology Applied
Scientific EffectLaminar flow: Laminar Flow

Implementation Method 2

The overall arrangement then acts as a pneumatic low-pass filter, i.e. vibrations with a frequency above a cut-off frequency are filtered out

Methodology Applied
Scientific EffectLow-pass filtering: Filter (physical)

Implementation Method 3

The laminar restrictor itself can be constructed from porous material that has pores of a predetermined size and length in order to make the gas volume flow that passes through laminar

Methodology Applied
Scientific EffectPorous flow: Porosity

Data Source

PatentEP1803970B1Vibration isolating system with pneumatic low-pass filter
Publication Date: 2011.10.05 INTEGRATED DYNAMICS ENG
  • EP1803970B1 patent drawingFigure 1
  • EP1803970B1 patent drawingFigure 2~3
  • EP1803970B1 patent drawingFigure 4~5

AI summary

The gas spring oscillation insulation system to decouple masses (6), e.g. vibration-sensitive photolithographic assemblies, has a combined vertical and horizontal gas spring (1). The gas spring has a flow resistance (5) in the gas feed line (4) between the gas flow control (3) and the gas pressure chamber (10), forming a deep pass filter with the gas volume in the chamber to reduce noise levels. The flow resistance can be fixed or variable and can be combined with a laminar restrictor.