Integral Stirling Cryocooler With Spring-Mass Phase Shifting
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Solution Overview
Problem
Cryogenic refrigeration systems, particularly Stirling coolers, face challenges in achieving optimal performance and efficiency due to parasitic pressure losses and vibration isolation issues in split configurations, while integral designs struggle with complexity and alignment precision.
Innovation Solution
An integral linear cryogenic refrigerator with a mechanically driven expander using a spring-mass-spring phase shifting mechanism, where a displacer is connected to a compressor via an auxiliary mass and springs, allowing for phase shifting of motion to optimize the coefficient of performance and reduce parasitic losses, utilizing a linear electric motor for actuation and a regenerative heat exchanger for efficient heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a split configuration with flexible gas transfer line is used, then vibration isolation and design flexibility are improved, but parasitic pressure losses and device complexity increase
Solution Approach 1:
The patent merges the compressor and expander into a single integrated housing, eliminating the flexible gas transfer line connection between separate units. This integration removes the parasitic pressure losses associated with flexible connections while maintaining vibration isolation through the shared housing structure that allows for dampening mechanisms.
2Loss of energy
If an integral configuration with common casing is used, then parasitic pressure losses are reduced and compactness is improved, but manufacturing complexity and alignment precision requirements increase
Solution Approach 1:
The patent segments the integral design into modular components (compressor assembly, expander assembly, regenerative heat exchanger) that can be manufactured separately with standard tolerances and then assembled within the common housing. This segmentation reduces the need for high-precision alignment while maintaining the benefits of integrated design.
Solution Approach 2:
The patent introduces intermediate connection elements and mounting structures within the common housing that act as mediators between the compressor and expander components. These intermediaries absorb alignment variations and facilitate assembly with looser tolerances while maintaining efficient gas flow paths.
3Use of energy by moving object
If a mechanically driven expander with phase shifting mechanism is used, then coefficient of performance is improved and power consumption is reduced, but device complexity increases
Solution Approach 1:
The patent designs the phase shifting mechanism to serve multiple functions: it not only optimizes the timing between compression and expansion strokes for improved coefficient of performance, but also acts as a vibration dampening system and enables compact packaging of the mechanically driven expander. This multi-functionality justifies the added complexity by delivering multiple performance benefits.
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 design enhances the coefficient of performance by optimizing phase shifts and reducing power consumption, achieving efficient heat pumping with lower parasitic losses and improved vibration isolation, independent of ambient temperature, and is more cost-effective and easier to produce with looser tolerances.
Implementation Method 1
a moving component configured to be driven back and forth within the housing along a longitudinal axis of the device by a linear electromagnetic actuator
Implementation Method 2
a displacer that includes a regenerative heat exchanger and that is configured to slide back and forth along the longitudinal axis within a cold finger
Implementation Method 3
The auxiliary mass may be connected to the moving component of the compressor by a drive spring and to the displacer plunger by a plunger spring, such that motion of the moving component of the compressor is transmitted to the displacer
Data Source
AI summary
Integral linear cryogenic Stirling refrigerator comprised of the free piston positive displacement pressure wave generator, the moving assembly of which is connected to the free piston displacer by the dynamic “spring-mass-spring” mechanical phase shifter the mechanical properties of which (spring rates and weight) are selected to provide a predetermined phase lag of motion of the displacer piston relative to the moving assembly of pressure wave generator.