Cryocooler Valve Seal Design for Stable Pressing Force Control
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Solution Overview
Problem
Cryocoolers face variations in pressing force between the valve stator and rotor due to pressure differences during operation, affecting the efficiency and stability of the cooling process.
Innovation Solution
A cryocooler design incorporating a three-stage seal system between the valve stator and rotor, with varying surface areas to stabilize pressure zones, minimizing the variation in pressing force across the valve's rotation cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single seal member is used between the valve stator and rotor, then the structure is simple, but the pressing force varies significantly during operation due to pressure differences
Solution Approach 1:
The single seal member is divided into three separate seal members (first, second, and third seal members) with different surface areas. Each seal member is positioned at different locations between the valve stator and rotor, creating segmented sealing zones that independently manage pressure distribution. This segmentation allows each seal member to experience different pressure forces, stabilizing the overall pressing force while maintaining structural manageability.
Solution Approach 2:
Each seal member is designed with a specific surface area tailored to its location and pressure conditions. The first seal member has a smaller surface area suited for high-pressure zones, while the second and third seal members have progressively larger surface areas for regions experiencing different pressure differentials. This local optimization of seal member properties ensures appropriate pressure distribution across the valve interface, stabilizing pressing force without excessive complexity.
2Reliability
If pressure differential is exploited to press valve stator and rotor into contact, then sealing is achieved, but pressing force varies during the rotation cycle affecting efficiency
Solution Approach 1:
The sealing function is segmented across three separate seal members rather than relying on a single seal member that experiences the full pressure differential. Each seal member handles a portion of the sealing task, distributing the pressure differential effects. This reduces the variation in pressing force during rotation, maintaining more consistent sealing effectiveness while improving cooling cycle efficiency through reduced sliding torque variations.
Solution Approach 2:
The surface areas of the seal members are specifically designed with different values to optimize pressure distribution. By changing the geometric parameter (surface area) of each seal member, the pressing force on each seal is adjusted to compensate for pressure differential variations during rotation. This parameter optimization maintains stable sealing while minimizing efficiency losses.
3Reliability
If valve stator and rotor are pressed together to prevent gas leakage, then sealing is improved, but stress concentration increases
Solution Approach 1:
The sealing interface is divided into three separate sealing zones with individual seal members. Each seal member carries a portion of the sealing load, distributing the contact stress across multiple locations between the valve stator and rotor. This segmentation prevents excessive stress concentration at any single point, reducing the risk of material fatigue and deformation while maintaining effective gas leakage prevention.
Solution Approach 2:
Each seal member is designed with a surface area optimized for its specific location and pressure conditions. The first seal member has a smaller surface area for high-pressure zones, while the second and third seal members have larger surface areas for regions with different pressure characteristics. This local optimization of contact area distributes stress more evenly across the valve interface, preventing stress concentration while maintaining sealing effectiveness.
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 design stabilizes the pressing force between the valve stator and rotor, enhancing the efficiency and reliability of the cryocooler's cooling cycle by maintaining consistent pressure differences, thereby reducing the sliding torque and stress concentration.
Implementation Method 1
pressure differential between the contact surface and a rear surface of the valve stator can be exploited
Data Source
AI summary
A cryocooler includes: a housing internally defining a low-pressure gas chamber; a valve stator defining a variable pressure zone and a high-pressure zone between the housing and the valve stator; a valve rotor, a first seal member disposed adjacent to the high-pressure zone to seal the high-pressure zone and encompassing a first surface area; a second seal member disposed adjacent to the variable pressure zone to seal the variable pressure zone, and encompassing a second surface area that is larger than the first surface area; and a third seal member disposed adjacent to the variable pressure zone to seal the variable pressure zone, and encompassing a third surface area that is larger than the second surface area.