Top Entry Plastic Ball Valve Design for Leakage Reduction
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Solution Overview
Problem
Traditional plastic ball valves face manufacturing and assembly difficulties due to complex processes, high costs, and inaccuracies in sealing ring positioning, leading to uneven pressing forces and potential leakage issues.
Innovation Solution
A top entry plastic ball valve design featuring a valve cover with a larger diameter hole above the valve ball chamber for direct mounting of sealing rings, allowing for end surface welding using hot melt, eliminating the need for electric fusion welding and enabling precise control of axial distances between sealing rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If electric fusion welding is used for large-diameter ball valves, then welding strength is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention extracts the valve stem and one sealing ring assembly from the traditional integrated side-entry structure, creating a separable top-entry configuration. This allows the valve body to be manufactured as a complete unit with the ball chamber and one sealing ring pre-installed, eliminating the need for complex electric fusion welding of the valve body and connecting pipe seat, while still achieving strong connections through hot melt welding of simpler geometries.
Solution Approach 2:
The invention replaces expensive and complex electric fusion welding processes with more economical hot melt welding processes. The connecting pipe seat is designed with a simplified structure that can be effectively joined using hot melt welding, which is cheaper and simpler than electric fusion welding, while still providing adequate connection strength for the application.
2Ease of manufacture
If hot melt welding is used for connecting pipe seat assembly, then manufacturing cost is reduced, but welding precision deteriorates
Solution Approach 1:
The invention performs preliminary assembly of the ball body and first sealing ring directly into the valve body before the hot melt welding process. The valve body is prepared with pre-formed hot melt welding surfaces that guide the connecting pipe seat into proper alignment. This preliminary positioning ensures that even though hot melt welding is used, the final alignment precision meets requirements by establishing correct geometry before the welding operation begins.
3Ease of operation
If traditional side-entry structure is used, then assembly process is simplified, but sealing ring positioning accuracy deteriorates
Solution Approach 1:
The invention transitions from a side-entry structure to a top-entry structure, changing the dimensional approach to sealing ring installation. The first sealing ring is installed from the top of the valve body through the valve cover hole, allowing direct vertical placement and positioning. This top-down approach provides better control over the sealing ring's axial and radial positioning compared to side-entry methods, achieving higher positioning accuracy while maintaining assembly simplicity.
Solution Approach 2:
The invention introduces a valve cover as an intermediary component that facilitates precise sealing ring positioning. The valve cover is fitted with a valve stem shaft hole and is designed to be hot melt welded to the valve body, creating a precise reference framework. The first sealing ring is installed through this valve cover assembly, which acts as a mediator to ensure accurate positioning of the sealing ring relative to the ball body, while the entire assembly can be easily manipulated during installation.
4Force
If valve stem buckling structure is used, then valve stem sealing force is improved, but manufacturing and assembly difficulty increase
Solution Approach 1:
The invention extracts the valve stem buckling structure from the traditional integrated design and relocates it to the valve cover assembly. The valve stem buckles with the valve cover instead of the valve body, separating the buckling function from the main valve body structure. This extraction simplifies the valve body manufacturing while concentrating the buckling mechanism in the valve cover, which is designed specifically to accommodate and guide the buckling action, thereby reducing overall manufacturing and assembly difficulty.
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 simplifies the manufacturing process, reduces costs, and ensures accurate pre-stressed forces and torsional moments, minimizing leakage risks and improving the overall quality of large-diameter valve assembly.
Implementation Method 1
the inner cylindrical surface of the insertion-accepting part of the valve body and the outer cylindrical surface of the connecting pipe are heated and molten on a hot melting machine
Data Source
AI summary
A top entry plastic ball valve comprises a valve stem cap (1), a valve stem (2), a valve stem sealing ring (3), a valve ball sealing ring (5), a supporting ring (6) for the valve ball sealing ring, a valve ball (7), a connecting pipe (8), and a valve body (9). A hollow valve ball chamber (911) is provided inside the valve body (9), the valve body (9) is provided with a valve cover hole (912) just above the valve ball chamber (911), and the width of the valve cover hole (912) is larger than the diameter of the valve ball (7). The ball valve also comprises a valve cover (4), which is provided with a valve stem shaft hole (410) for allowing the valve stem (2) to pass through and corresponds to the valve cover hole (912) so that the valve cover (4) can cover the valve cover hole (912) and can be fusion-bonded to the valve body (9), thereby avoiding the need for electric fusion welding process in the manufacture of large-diameter ball valves.