Linear-Drive Cryogenic Refrigerator With Independent Stage Control
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Solution Overview
Problem
Conventional cryogenic refrigerators face inefficiencies due to the interdependence of their stages, which limits independent control over stroke length, speed, and phase, making it difficult to meet varying cooling requirements and increasing overall system size and energy consumption.
Innovation Solution
The implementation of independent linear motors for each stage of the cryogenic refrigerator allows for distinct control of stroke length, speed, and phase, enabling separate optimization of the first and second stages without requiring a complete redesign, along with the option for different working fluids and vibration damping to enhance efficiency and adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common rotary motor drives both first and second displacers, then the device complexity is reduced, but the adaptability of each stage to different loading conditions deteriorates
Solution Approach 1:
The patent divides the common rotary drive into separate linear drives for the first and second stages. Each stage has its own linear motor (140a, 140b) that independently controls its displacer, allowing each stage to be optimized for different loading conditions while maintaining structural integration through coaxial arrangement.
2Device complexity
If the second stage depends entirely on the first stage, then the device complexity is reduced, but the productivity of the second stage deteriorates
Solution Approach 1:
The patent segments the stage operations by providing independent linear motors for each stage, allowing the second stage to operate independently with optimized stroke parameters rather than being constrained by the first stage's performance characteristics.
3Ease of operation
If a mechanical rotary drive operates both stages with the same stroke parameters, then the ease of operation is improved, but the use of energy deteriorates
Solution Approach 1:
The patent implements dynamic control where each linear motor can independently adjust its stroke length, speed, and displacement profile according to the specific loading conditions of each stage, optimizing energy efficiency rather than operating with fixed synchronized parameters.
4Productivity
If the stroke parameters are changed to increase efficiency, then the productivity is improved, but the device complexity increases due to redesign requirements
Solution Approach 1:
The patent enables dynamic adjustment of stroke parameters through independent linear motor control, allowing efficiency optimization without mechanical redesign. The control system can modify stroke length, speed, and phase independently for each stage to match varying loading conditions.
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
This approach allows for improved temperature control and efficiency by enabling independent operation of each stage, reducing excess capacity and energy usage, and accommodating a wide range of cooling requirements with increased precision and reduced vibration.
Implementation Method 1
The linear motor is operatively connected to a displacer. In another stage of the refrigerator, a second linear motor is operatively connected to a second displacer
Implementation Method 2
a working fluid, such as helium, is introduced into a cylinder, and the fluid is expanded at one end of a piston or displacer to cool a refrigeration cylinder
Data Source
AI summary
A cryogenic refrigerator has a refrigeration cylinder and at least two displacers. Each displacer reciprocates in the refrigeration cylinder and moves refrigeration gas through the refrigeration cylinder. A regenerator cools the refrigeration gas, and gas control valves admit high pressure gas into the refrigeration cylinder and exhaust gas from the refrigeration cylinder. The refrigerator also has linear motors operatively connected to displacers, and the linear motors drive the displacers in reciprocating movement. A position sensor is provided to determine a parameter of the displacers during reciprocation. A controller is operatively connected to the linear motors to control the linear motors. The controller controls a parameter of the two displacers during reciprocation. The parameter can be stroke length, stroke speed, stroke phase or another parameter of the displacer for temperature control of the cryogenic refrigerator. The cryogenic refrigerator may also include a device to remove vibration.