Symmetrical Stem Trunnion Ball Valve for Hydrogen Stations
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Solution Overview
Problem
High-pressure trunnion ball valves face challenges in maintaining low torque performance and valve seat sealing efficiency under high pressure, with existing designs experiencing large operation torques and complex structures that complicate assembly and maintenance.
Innovation Solution
A high-pressure trunnion ball valve design featuring symmetrical upper and lower stems with balanced shaft-attaching seal mechanisms, a spring member for elastic force application, and a bottom entry structure with flange portions to prevent thrust loads and ensure even force distribution, along with diamond-like carbon coatings for improved lubricity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-pressure ball valve uses a conventional stem seal structure with O-rings in grooves, then it can accommodate moderate pressures (up to 41 MPa), but it cannot seal high-pressure fluids (exceeding 41 MPa) and the O-ring may fly out of the groove
Solution Approach 1:
The patent changes the seal member material from elastomeric O-rings to PTFE (polytetrafluoroethylene) which has different physical properties including higher temperature resistance and pressure resistance. This material parameter change enables the valve to accommodate pressures exceeding 41 MPa while maintaining sealing reliability.
Solution Approach 2:
The patent employs PTFE as a composite material solution for the seal member, utilizing its unique properties of chemical inertness, low friction coefficient, and high pressure resistance. This composite material approach resolves the limitation of conventional O-ring materials at high pressures.
2Stability of the object's composition
If a high-pressure ball valve uses radial bearings and thrust bearings to support the ball under high pressure, then it can maintain structural stability, but the operation torque becomes large and the structure becomes complicated
Solution Approach 1:
The patent introduces a counterbalancing spring mechanism that applies a force opposite to the thrust force generated by high-pressure fluid on the ball. This counterweight principle reduces the net thrust load on the stem, thereby reducing operation torque while maintaining structural stability under high pressure.
Solution Approach 2:
The patent extracts and eliminates the thrust bearing component from the conventional design. By using the counterbalancing spring mechanism instead, the design removes the complex thrust bearing structure while still achieving the function of supporting the ball under high pressure with reduced operation torque.
3Strength
If a high-pressure ball valve uses a divided stem structure with separate upper and lower stems, then it can support the ball, but the structure becomes complicated and assembly and maintenance become time-consuming
Solution Approach 1:
The patent merges the upper stem and lower stem into a single integrated stem structure. This combining of parts simplifies the overall stem structure, reduces the number of components, and makes assembly and maintenance less time-consuming while still providing adequate support for the ball under high-pressure conditions.
4Reliability
If a high-pressure ball valve uses enhanced rigidity seal members to prevent O-ring flyout, then it can maintain sealing at high pressure, but it becomes difficult to attach the seal member to the groove on the stem
Solution Approach 1:
The patent changes the seal member material from elastomeric O-rings to PTFE with different mechanical properties. PTFE has lower tensile strength and is more compliant, allowing it to be easily attached to grooves while still providing high-pressure sealing capability and resistance to flyout.
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 achieves stable and constant operation torque, enhanced sealing performance, and reduced valve size, eliminating the need for thrust bearings and simplifying assembly while maintaining high-pressure fluid sealing efficiency.
Implementation Method 1
a spring member applying an elastic force toward a seal side to the seat retainer
Implementation Method 2
diamond-like carbon coatings for improved lubricity and durability
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A high-pressure trunnion ball valve which is particularly suitable for a high-pressure fluid, suppresses a thrust load to a stem to realize low torque performance while maintaining a valve seat sealing performance even under a high pressure, and can perform opening and closing operations by an approximately constant and stable operation torque and can be made small, and a hydrogen station using the same are provided. The high-pressure trunnion ball valve is composed of a ball 10 rotatably provided in a body 3 having a lid member 2, a seat retainer 11 seal-connected to the ball 10, a spring member 12 applying an elastic force to the seat retainer 11 to a seal side, and a seal member 13 attached to an outer circumferential face of the seat retainer 11. An upper stem 50 and a lower stem 51 having the same diameter are provided on an upper side and a lower side of the ball 10 in an extending manner, respectively, to constitute a ball member 52, shaft-attaching seal mechanisms 20 having the same structure are attached to the upper and lower stems 50 and 51 at symmetrical positions regarding the ball 10 to achieve a balance structure, thereby avoiding thrust loads.