Dynamic Ball Valve Seal Compensating for Tolerances
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Solution Overview
Problem
Ball valves face challenges in achieving leak-free sealing due to machining tolerances and pressure differentials, which can cause the valve member to flex or move out of sealing contact, requiring larger actuators and increasing operational costs.
Innovation Solution
A dynamic seal member that moves relative to the valve body and valve member, compensating for variations in machining tolerances and pressure-induced flexure, allowing for adjustable positioning to maintain sealing contact regardless of component variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed position seals are used to compensate for machining tolerances by being oversized, then sealing reliability is improved, but the load on the valve member increases making it more difficult to rotate
Solution Approach 1:
The seal member is made movable within the valve body rather than fixed, allowing it to dynamically adjust its position in response to pressure differentials and valve member movement. This dynamic capability enables the seal to maintain reliable sealing contact without requiring excessive compression force, thereby reducing the load on the valve member while preserving sealing reliability.
2Device complexity
If fixed position seals are used, then device complexity is reduced, but sealing performance deteriorates under varying pressure differentials and fluid flow directions
Solution Approach 1:
The seal member transitions from a fixed position to a movable position, enabling it to adapt to varying pressure differentials and fluid flow directions. This dynamic adjustment maintains sealing performance across different operating conditions without significantly increasing device complexity, as the movement is achieved through the natural pressure differential acting on the seal member itself.
3Ease of operation
If larger actuators are used to overcome the loads from oversized seals, then the valve member can be rotated, but operational cost increases
Solution Approach 1:
The movable seal member reduces the friction and load resistance during valve member rotation by maintaining optimal sealing contact without excessive compression. This reduces the torque requirement for actuators, enabling easier rotation with smaller, more energy-efficient actuators, thereby reducing operational costs.
4Reliability
If the seal member is permitted to move dynamically, then sealing contact is maintained under varying conditions, but device complexity increases
Solution Approach 1:
The seal member is designed to move automatically in response to pressure differentials without requiring external control mechanisms. The pressure differential itself drives the seal member to the appropriate position, making the system self-regulating and minimizing the need for additional control components, thereby limiting the increase in device complexity.
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 dynamic seal member ensures reliable leak-free sealing across various positions and pressure conditions, reducing the need for powerful actuators and enhancing operational efficiency by adapting to changes in the valve member's position and pressure differentials.
Implementation Method 1
the biasing member biases the seal member in a direction out of the valve chamber
Data Source
AI summary
A ball valve having improved sealing between the valve member and the valve body is presented. Improved sealing is realized by providing a sealing member that is allowed to float on the outer surface of the valve member in the closed position. By being able to float on the outer surface, the sealing member can compensate for any variations in the valve member as a result of machining tolerances or variations in position of the valve member due to changes in pressure within the valve, thereby providing dynamic sealing The dynamic sealing is also provided by configuring the valve member such that it causes the sealing member to be exposed to a higher biasing force in the closed position than in the open position.