Ball Valve Stem Coupling via Intermediary Body
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Solution Overview
Problem
Existing ball valves face issues with unreliable coupling between the stem and spherical element, leading to potential detachment during maintenance, imperfect closure due to axial misalignment, and corrosion of metallic spherical elements from aggressive fluids, resulting in leaks and increased maintenance costs.
Innovation Solution
A ball valve design featuring a plastic spherical element with a receptacle for an intermediate metallic body that locks the stem, allowing for rotational and translational locking, and using a sealing mechanism with a rubber annular body and metallic insert to ensure reliable connection and sealing, while accommodating machining tolerances and reducing corrosion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct coupling by interference is used between stem and spherical element, then manufacturing is simple, but coupling reliability deteriorates causing detachment during maintenance
Solution Approach 1:
A square intermediate body is introduced as a mediator between the stem and spherical element. The intermediate body features a locking portion that engages with a transverse recess in the stem, preventing detachment while maintaining ease of assembly. This intermediary component resolves the contradiction by providing reliable coupling without complex manufacturing processes.
2Device complexity
If direct coupling is used without perfect axial alignment, then device complexity is reduced, but manufacturing precision deteriorates causing imperfect closure and gasket damage
Solution Approach 1:
The intermediate body acts as a precision alignment mediator, featuring a locking portion with specific geometric constraints that ensure accurate axial positioning of the stem relative to the spherical element. This intermediary component compensates for machining tolerances and ensures perfect closure without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The intermediate body is pre-configured with a locking portion and transverse recess geometry that establishes correct axial alignment before final assembly. This preliminary geometric configuration ensures proper alignment is achieved automatically during assembly, eliminating the need for post-assembly adjustment and preventing gasket damage.
3Strength
If metallic spherical elements are used, then strength is improved, but corrosion resistance deteriorates due to aggressive agents in controlled fluids
Solution Approach 1:
The spherical element is constructed from composite materials combining a plastic base material with embedded metallic reinforcement elements or coatings. This composite structure provides both the mechanical strength of metal and the corrosion resistance of plastic, resolving the contradiction between strength and corrosion resistance in aggressive fluid environments.
4Reliability
If plastic spherical element with intermediate body is used, then coupling reliability is improved, but device complexity increases
Solution Approach 1:
The intermediate body, while adding a component, simplifies the overall coupling mechanism by providing a standardized interface with a transverse recess that easily receives the locking portion. This intermediary design actually reduces assembly complexity and improves reliability simultaneously, as the geometric constraints automatically ensure proper alignment and secure coupling without requiring complex adjustment procedures.
Data Source
Figure 1
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AI summary
A ball valve (1) for controlling the flow of fluids in ducts, comprising a hollow valve body (11) that defines in an upward region an access mouth (11a) and having at least two open tubular portions (12, 13) for detachable connection to a respective duct portion, a hollow spherical control element (2) accommodated in the hollow valve body (11), the spherical element (2) having at least one flow passage (2a) and being movable rotatably between at least one position for allowing flow and a flow control position, a stem (3) adapted to be jointly connected to the spherical element (2) and actuatable to allow the rotation of the spherical element (2) through a preset angle from the flow-allowing position to the control position and vice versa, the access mouth (11 a) being crossable by the stem (3), the spherical element (2) being jointly connected to the lower end (3a) of the stem (3) by way of the interposition of connection means (4); the connection means (4) comprise a receptacle (5) that is defined on the spherical element (2), the receptacle (5) being intended to accommodate an intermediate body (6) and being adapted to lock the intermediate body (6) rotationally about the axis (100) of the access mouth (11a) and in translation parallel to the axis (100) of the access mouth (11a), the intermediate body (6) defining a locking seat for the lower end (3a) of the stem (3).