Valve Stem Retention in Rotary Valves
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Solution Overview
Problem
Trunnion-mounted rotary elements in larger diameter valves face issues with securing the valve stem within the valve body, leading to potential blowout due to bolt fatigue from repeated actuator forces, as existing designs rely on external plates and fasteners.
Innovation Solution
A rotary valve design featuring a valve stem with an enlarged portion that secures within the valve body, utilizing split support elements and extensions to prevent radially outward movement, eliminating the need for external fasteners and ensuring the valve stem is retained without bolts, even under pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external plate with bolts is used to secure the valve stem to the valve body in trunnion-mounted valves, then the valve stem can be retained, but the bolts may fatigue from repeated actuator forces causing potential valve stem release
Solution Approach 1:
The invention extracts and eliminates the external plate and bolts from the valve stem retention system. Instead of using fasteners, the valve stem is directly retained within the valve body through its enlarged end portion that fits into a recess in the valve body, removing the fatigue-prone bolted connection entirely.
Solution Approach 2:
The invention merges the valve stem retention function directly into the valve body structure. The enlarged end of the valve stem and the corresponding recess in the valve body form an integrated retention mechanism, eliminating the need for separate fastening components like plates and bolts.
2Reliability
If an enlarged end is provided on the valve stem to retain it within the valve body, then the valve stem becomes blowout proof, but this design cannot be used with trunnion mounted rotary elements due to insertion constraints
Solution Approach 1:
The invention segments the trunnion structure into separate halves that can be assembled around the rotary element and valve stem. The trunnions are provided as split components that can be installed from the sides of the valve body, allowing the valve stem with its enlarged end to be inserted first and retained before the trunnion halves are closed around it.
Solution Approach 2:
The invention changes the assembly approach from axial insertion (through the valve body) to lateral assembly (from the sides). The split trunnions are assembled from the sides of the valve body rather than requiring the valve stem to be inserted axially through the complete assembly, enabling both the enlarged end retention and trunnion mounting to coexist.
3Strength
If trunnion mounted rotary elements are used in larger diameter valves, then the rotary element is securely supported, but the valve stem cannot be retained within the valve body without external fasteners
Solution Approach 1:
The invention extracts and removes the external fastener system (plates and bolts) from the valve stem retention mechanism. The retention is achieved through the enlarged end of the valve stem fitting into a recess in the valve body, eliminating the need for complex external fastening systems while maintaining secure retention.
Data Source
AI summary
A valve body defines a valve stem opening. A valve stem comprises an enlarged portion greater than the valve stem opening to thereby secure the valve stem within the valve body by limiting radially outward movement of the valve stem with respect to the valve body. A rotary member comprise upper and lower bosses. Upper and lower split trunnions, with split components that can be inserted from opposite sides of the valve body, are used to rotationally support the upper and lower bosses to permit rotation of the rotary member while preventing axial movement of the axial flow path of the valve.