Valve for a refrigeration application
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Solution Overview
Problem
Existing refrigeration valves experience premature seal deterioration due to permanent compression, leading to potential leaks when the valve is closed, as the seals are only needed during a negligible fraction of the valve's operating time.
Innovation Solution
The valve design features a bonnet and piston with varying diameters, ensuring that seals are only significantly compressed in the closed or nearly closed positions, reducing compression in open positions and extending seal life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seals are permanently compressed during total operating time to ensure sealing in closed position, then sealing reliability is improved, but seal deterioration accelerates and service life decreases
Solution Approach 1:
The bonnet is designed with variable cross-sectional area along its length, creating different radial clearances at different positions. The upper portion has a larger cross-sectional area providing greater radial clearance, while the lower portion has a smaller cross-sectional area providing lesser radial clearance. This dynamic clearance variation allows seals to be uncompressed during open position (reducing deterioration) while maintaining sealing capability during closed position.
Solution Approach 2:
Different radial clearances are provided at different locations along the bonnet-piston assembly. The upper guiding and sealing portion operates with a larger radial clearance compared to the lower portion, allowing the seal to remain uncompressed during most of the operating cycle while still providing adequate sealing when needed in the closed position.
2Duration of action of stationary object
If radial clearance between bonnet and piston is reduced to minimize seal compression, then seal deterioration is reduced, but sealing reliability in closed position may be compromised
Solution Approach 1:
The variable cross-sectional area of the bonnet creates a dynamic radial clearance system that adapts to valve position. During open position, the larger clearance minimizes seal compression and extends service life. During closed position, the geometry ensures adequate contact for reliable sealing, thus dynamically optimizing both seal longevity and sealing performance.
Solution Approach 2:
The radial clearance parameter is varied along the length of the bonnet, with the upper portion having a larger clearance and the lower portion having a smaller clearance. This parameter variation allows the system to maintain appropriate seal compression levels different from what a uniform clearance would provide, extending seal life while ensuring sealing reliability.
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 reduces the radial forces on the piston, minimizes seal compression and deterioration, and enhances the valve's performance by reducing the likelihood of turbulences and sticking issues.
Implementation Method 1
Pressure balancing is provided in order to overcome the forces or reduce the net forces acting on the closure member, which are generated by the pressure difference over the closure member when the valve is closed or nearly closed. Pressure balanced valves are typically designed such that the pressure generated forces acting opposite to each other and in the axial direction of the closure member equal each other.
Implementation Method 2
For the piston against the bonnet, seals are provided between the piston and the bonnet. The piston is sealed against the bonnet at the upper guiding and sealing portion
Data Source
AI summary
The present disclosure pertains to a valve for a refrigeration application, in particular a shut-off and/or regulating valve. The valve includes a bonnet connected to a housing with two fluid openings, a spindle fully penetrating the bonnet and reaching inside the housing, and a piston with an upper guiding and sealing portion with a seal section, a bottom closing portion for opening and closing a fluid passage between the two fluid openings, and a piston tube between the upper guiding and sealing portion and the bottom closing portion. The spindle engages the piston for moving it between a closed position and an open position of the valve and a pressure balancing chamber is provided above and within the piston. The piston is sealed against the bonnet at the upper guiding and sealing portion. An inner surface of the bonnet guiding the upper guiding and sealing portion and/or an outer surface of the piston has a smaller diameter at a bottom portion than at an upper portion.