Opposed Diaphragm Pressure Wave Generator for Cryogenic Refrigerators

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Solution Overview

Problem

Existing pressure wave generators for cryogenic refrigerator systems are costly and inefficient, as they rely on clearance gap pistons driven by linear motors, which are not suitable for generating reciprocating pressure waves effectively.

Innovation Solution

A pressure wave generator utilizing a pair or pairs of opposed diaphragms driven in a reciprocating motion by a drive system, with each diaphragm generating pressure waves that are 180 or 90 degrees out of phase, and connected via an orifice to balance gas forces, allowing efficient operation and reduced costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If clearance gap pistons driven by linear motors are used to generate pressure waves, then the cryogenic refrigerator system can operate, but the cost is high and efficiency is reduced

Engineering Contradiction:
Improvepressure wave generation capabilityVSAvoidcost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive clearance gap pistons and linear motors with disposable diaphragms that can be easily manufactured and replaced. The diaphragms are simple elastomeric membranes that成本低廉, eliminating the need for costly motor-piston assemblies while maintaining pressure wave generation capability.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the mechanical clearance gap piston system with a diaphragm-based acoustic wave generation system. Instead of using motor-driven mechanical pistons, the system uses elastomeric diaphragms that respond to pressure differentials, replacing complex electromechanical systems with simpler elastic deformation mechanisms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If clearance gap pistons driven by linear motors are used to generate pressure waves, then the cryogenic refrigerator system can operate, but efficiency is reduced

Engineering Contradiction:
Improvepressure wave generation capabilityVSAvoidefficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces expensive clearance gap pistons and linear motors with disposable diaphragms that can be easily manufactured and replaced. The diaphragms are simple elastomeric membranes that成本低廉, eliminating the need for costly motor-piston assemblies while maintaining pressure wave generation capability.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the mechanical clearance gap piston system with a diaphragm-based acoustic wave generation system. Instead of using motor-driven mechanical pistons, the system uses elastomeric diaphragms that respond to pressure differentials, replacing complex electromechanical systems with simpler elastic deformation mechanisms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Quantity of substance

If multiple pump elements are radially arranged around a driving shaft, then vacuum production is achieved, but the configuration is not suitable for generating reciprocating pressure waves

Engineering Contradiction:
Improvevacuum productionVSAvoidsuitability for reciprocating pressure waves
Core Design Contradiction:
Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent inverts the conventional pump architecture by placing diaphragms at the ends of a reciprocating drive part rather than arranging pump elements around a rotating shaft. This inversion transforms the system from a rotational vacuum pump to a reciprocating pressure wave generator suitable for cryogenic refrigeration.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent uses flexible diaphragms as the primary moving components instead of rigid pump elements. These thin film diaphragms can deform elastically to generate reciprocating pressure waves, providing the necessary adaptability for cryogenic refrigerator operation while maintaining simplicity.

Inventive Principle:
Principle #30Flexible shells and thin films

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 enables efficient generation of reciprocating pressure waves for driving cryogenic refrigerator systems, improving efficiency and reducing costs by using a low-cost diaphragm-based mechanism that isolates the clean gas environment from the driving system, achieving balanced gas forces and dynamic balance of reciprocating masses.

Implementation Method 1

a connection pipe between the two gas spaces, the connection pipe comprising an orifice configured to reduce gas flow between the two gas spaces to negligible levels that are sufficient to balance the average gas forces on the opposed diaphragms

Methodology Applied
Scientific EffectGas flow restriction through orifice: Pressure Drop

Implementation Method 2

each diaphragm comprising a driving side, each pair of opposed diaphragms being driven in a reciprocating motion by a respective reciprocating drive part... the driving side of each diaphragm is arranged to move in a reciprocating motion within its respective gas space to generate reciprocating pressure waves

Methodology Applied
Scientific EffectPressure wave generation: Acoustic Radiation Pressure

Data Source

PatentEP1877710B1Pressure wave generator
Publication Date: 2018.08.15 CALLAGHAN INNOVATION
  • EP1877710B1 patent drawingFigure 1
  • EP1877710B1 patent drawingFigure 2
  • EP1877710B1 patent drawingFigure 3

AI summary

A pressure wave generator (40) for driving one or more cryogenic refrigerator systems. The pressure wave generator (40) comprises a housing with one or more inlet/outlet ports (57,58) through which generated pressure waves of gas may pass through to drive a cryogenic refrigerator system or systems connected to the inlet/outlet ports (57,58). The pressure waves are generated by at least one pair of opposed diaphragms (41,42) located in the housing that are moveable in a reciprocating motion within the housing to create pressure waves in gas spaces (55,56) associated with each diaphragm (41,42). The gas spaces (55,56) each having associated inlet/outlet ports (57,58) through which the pressure waves may pass. An operable drive system is also provided to move the pair of diaphragms (41,42) in a reciprocating motion.