GM Cryocooler Rotary Valve Timing for Overlapping Intake and Exhaust
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Solution Overview
Problem
Existing GM cryocoolers face inefficiencies due to separate and non-overlapping intake, exhaust, and pressure equalization steps, which limit their cooling capacity and compressor efficiency.
Innovation Solution
A GM cryocooler design with a valve structure that includes a rotary valve portion with a rotor and stator, allowing for overlapping intake and exhaust periods with pressure equalization, optimizing the valve timing to enhance cooling capacity and compressor efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If separate and non-overlapping intake, exhaust, and pressure equalization steps are used, then the valve structure is simple, but the cooling capacity is limited and compressor efficiency is reduced
Solution Approach 1:
The patent merges the intake valve, exhaust valve, and pressure equalizing valve into a single rotary valve assembly where all three functions are performed by different flow paths within the same rotating component structure, allowing overlapping operations without increasing overall device complexity
Solution Approach 2:
The patent uses a rotary valve mechanism where the rotor rotates to dynamically switch between different flow paths (intake, exhaust, and pressure equalization), enabling temporal overlap of these functions through dynamic positioning rather than static separate valves
2Power
If separate and non-overlapping intake, exhaust, and pressure equalization steps are used, then the drive mechanism is larger, but the compressor efficiency is reduced
Solution Approach 1:
The patent combines multiple valve functions into a single rotary assembly, reducing the number of separate drive mechanisms needed and thereby reducing the overall size and weight of the drive system while improving compressor efficiency through optimized timing
Solution Approach 2:
The rotary valve serves multiple functions (intake, exhaust, and pressure equalization) through different flow paths within the same component, allowing a single drive mechanism to control all three functions with optimized overlapping timing, improving efficiency without increasing size
3Productivity
If overlapping intake and exhaust periods with pressure equalization are implemented, then the cooling capacity and compressor efficiency are improved, but the valve structure becomes more complex
Solution Approach 1:
The rotary valve mechanism dynamically switches between different flow paths during rotation, enabling overlapping intake, exhaust, and pressure equalization operations through temporal sequencing of flow path openings, achieving improved cooling capacity through dynamic control rather than static complex structures
Solution Approach 2:
The overlapping valve timing ensures continuous useful action by allowing intake, exhaust, and pressure equalization to occur in overlapping periods rather than sequentially, maximizing the utilization of each stroke and improving cooling capacity through continuous optimized gas flow management
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 overlapping valve timing improves the cooling capacity and reduces drive torque, leading to increased efficiency and reduced size of the drive mechanism, while maintaining efficient pressure equalization between cold heads.
Implementation Method 1
a valve rotor which has a rotor plane perpendicular to a valve rotation axis to be in surface contact with the stator plane and is rotatable around the valve rotation axis with respect to the valve stator
Implementation Method 2
periodic pressure fluctuation in an expansion space configured of intake of a working gas into the expansion space, adiabatic expansion of the working gas
Data Source
AI summary
A GM cryocooler includes a valve portion which defines a valve group including a first intake valve, a first exhaust valve, and a pressure equalizing valve. A valve rotor of the valve portion includes a rotor plane which is in surface contact with a stator plane of a valve stator. The valve rotor includes a high pressure flow path which is open to the rotor plane to form a portion of the first intake valve, a low pressure flow path which is open to the rotor plane to form a portion of the first exhaust valve, and a pressure equalization flow path which is open to the rotor plane to form a portion of the pressure equalizing valve, and the high pressure flow path, the low pressure flow path, and the pressure equalization flow path are circumferentially arranged around a valve rotation axis on the rotor plane.