Balloon and Bellows Compressor Membranes for Low-Loss Cryocooling
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Solution Overview
Problem
Existing compressor systems for cryogenic applications, such as pulse tube and Gifford-McMahon coolers, suffer from inefficiencies due to motor-driven rotary valves causing power losses and costly, short-lived sealing materials in membrane compressors, while balloon-based systems risk damage from pressure-induced rubbing against chamber surfaces.
Innovation Solution
A compressor device featuring a gas volume enclosed within a balloon or tubular bellows, protected by a liquid film and using a working fluid reservoir, with a gear pump and differential pressure regulation to manage pressure and prevent damage, employing hydraulic oil or water as the working fluid for enhanced durability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a motor-driven rotary valve is used to connect high and low pressure sides alternately, then the cooling device can operate, but power losses of up to 50% occur
Solution Approach 1:
The invention extracts and eliminates the motor-driven rotary valve from the system by using a membrane compressor that integrates the compression and pressure alternation functions directly into the compression chamber, thereby removing the source of 50% power losses while simplifying the overall device structure
Solution Approach 2:
The invention merges the functions of the rotary valve and compressor into a single membrane compressor unit where the membrane directly creates alternating high and low pressure zones without requiring separate valve mechanisms, eliminating energy losses and reducing device complexity
2Reliability
If an elastic membrane is used for gas compression, then compressor function is achieved, but sealing costs increase and service life decreases due to heavy loading
Solution Approach 1:
The invention uses a membrane as a flexible sealing element that divides the compression chamber into gas and liquid volumes, achieving effective sealing while distributing mechanical loads to reduce stress concentration and extend service life, avoiding the need for expensive sealing materials
Solution Approach 2:
The invention uses a liquid medium (hydraulic oil or water) pumped into the liquid volume to transmit pressure forces to the membrane, achieving smooth pressure transmission that reduces mechanical shocks and heavy loading on the sealing membrane, thereby extending service life and reducing costs
3Reliability
If a balloon is used to enclose working gas in a compressor chamber, then gas compression is achieved, but the balloon envelope can scrape or rub against the chamber surface causing holes or tears
Solution Approach 1:
The invention introduces a liquid medium as an intermediary between the balloon envelope and the compressor chamber wall, creating a protective lubricating film that prevents direct contact and rubbing, thereby eliminating mechanical damage and holes while maintaining compression functionality
Solution Approach 2:
The invention uses a balloon or flexible membrane to enclose the working gas, allowing the balloon to deform and adapt to pressure changes while the surrounding liquid medium provides cushioning and prevents direct contact with hard chamber surfaces, protecting against scraping and tearing
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 compensates for volume reductions at low temperatures, reduces power losses, and prevents damage to the compressor components, ensuring efficient operation and extended service life with improved sealing and pressure management.
Implementation Method 1
the elastic membrane expands in the direction of the gas volume and compresses it
Implementation Method 2
one or more pistons are set into linear resonance oscillations by a magnetic field. These resonant frequencies are in the range of a few 10 Hz
Implementation Method 3
employing hydraulic oil or water as the working fluid for enhanced durability and safety
Implementation Method 4
The balloon envelope is always protected from damage by a liquid film on the hard inside
Data Source
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AI summary
The invention relates to an economical compressor device having an elastic membrane (6) and to a cooling device equipped therewith and a refrigeration machine equipped therewith, wherein working liquid (14) is present on one side of the membrane and the working gas (10) to be compressed is present on the other side of the membrane (6). The membrane is designed as a balloon (6) or bellows (80). Because the gas volume (8) is in the balloon (6) and the liquid volume (12) is outside, the balloon shell is always protected from damage by a liquid film on the hard inner surface (generally made of metal) when the balloon shell rubs on the hard inner surface of the compressor chamber due to irregular operating conditions. Because the working liquid is generally hydraulic oil, the protective effect is additionally improved by the lubricating oil effect. Instead of a balloon (6), a tubular bellows (80) can also be used as the membrane. The bellows (80) has the advantage that the volume enlargement or volume reduction is "directed" in the longitudinal direction of the bellows (80) due to the design and the arrangement of the folds. Therefore, rubbing contact between the bellows (80) and the hard inner surface of the compressor chamber (4) is nearly impossible. Thus, if a bellows (80) is used as the compressor membrane, the gas volume (8) can also be provided inside the bellows. This "directedness" of the volume change can be improved by positive guidance of the bellows (80) along a rod having a longitudinal bearing. The bellows (80) is usually made of a stainless steel alloy and is extremely gas-tight for all relevant working gases (10), the exception being hydrogen.