Ball Valve External Seal Layout for Refrigerant Leakage Control
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Solution Overview
Problem
Ball valves in motor vehicle refrigerant systems face challenges with internal and external tightness, particularly under high temperature and pressure conditions, and existing components are not adequately suited for modern refrigerant systems with integrated functionalities like heat pumps, leading to issues with fluid leakage and component durability.
Innovation Solution
A ball valve design featuring a double sealing system with a sealing fluid reservoir, utilizing polyalkylene glycols or oil as sealing fluid, and a diaphragm to equalize pressure between the fluid and sealing fluid, combined with an external O-ring or molded seal for enhanced external sealing, and an internal O-ring for media separation, minimizing thermal stress on the actuator and ensuring tightness across temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single sealing system is used, then device complexity is reduced, but external tightness deteriorates under high temperature and pressure conditions
Solution Approach 1:
The sealing system is divided into multiple independent sealing stages: a first sealing element (mechanical seal) and a second sealing element (O-ring or molded seal), each addressing specific sealing requirements. This segmentation allows each element to be optimized for its specific function while collectively providing robust external tightness under high temperature and pressure conditions.
Solution Approach 2:
The invention incorporates a sealing fluid (oil or polyalkylene glycol) in advance within the sealing chamber to provide a cushioning effect. This sealing fluid compensates for thermal expansion and contraction, maintaining sealing contact between moving parts despite temperature variations, thereby preventing refrigerant leakage before it occurs.
2Reliability
If sealing fluid is added to the sealing chamber, then external tightness is improved, but device complexity increases due to additional components
Solution Approach 1:
The sealing chamber is designed to combine multiple functions: it houses the sealing fluid reservoir, accommodates the shaft rotation, and provides the sealing interface between the first and second sealing elements. By merging these functions into a single integrated chamber, the design avoids adding excessive complexity while achieving improved sealing effectiveness.
Solution Approach 2:
The sealing fluid automatically adjusts to thermal conditions without external intervention. As temperature changes cause thermal expansion or contraction of components, the sealing fluid maintains constant pressure contact with the sealing surfaces, self-regulating the sealing force and eliminating the need for complex thermal compensation mechanisms.
3Adaptability or versatility
If bidirectional insertability is required, then adaptability is improved, but maintaining tightness under high temperature and pressure becomes more difficult
Solution Approach 1:
The ball valve is designed with symmetrical sealing surfaces and a centrally positioned ball element that can effectively seal in either flow direction. The sealing elements are configured to engage with the valve body regardless of insertion orientation, allowing bidirectional installation while maintaining reliable tightness under high temperature and pressure conditions in both directions.
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 high external tightness and efficient sealing, reducing refrigerant leakage, and extends the operational life of the valve by maintaining sealing integrity under high temperature and pressure variations, while allowing for easy maintenance and adaptation to various valve configurations.
Implementation Method 1
the sealing fluid surrounds the shaft in a sealing region, so that, in the axial direction of the shaft, a sealing effect is present due to the sealing fluid
Implementation Method 2
The diaphragm is formed in such a way that pressure can be applied to the side facing away from the sealing fluid, so that the pressure is transferred by means of the flexible diaphragm from outside of the sealing fluid space to the sealing fluid, and thus the pressure is the same on the two sides of the diaphragm
Implementation Method 3
the moving shaft used for the actuating movement of the valve body has to be sealed with respect to the environment, in order to prevent the discharge of the fluid to be regulated via the rotatably mounted shaft
Data Source
AI summary
A ball valve (1), particularly for use in motor vehicle refrigerant circuits, having an actuator (2), a shaft (3) including a shaft bearing (5), a ball (4) including a ball passage (16), and a valve housing (13). A fluid shaft seal (8) is arranged in the shaft bearing (5) between an upper shaft seal (6) and a lower shaft seal (7), wherein the fluid shaft seal (8) is formed by a cavity (18) in which a sealing fluid is provided, and that the sealing fluid is in contact with the shaft (3) in a sealing region (19) such that the sealing fluid has a sealing effect in the axial direction, wherein the cavity (18) is at least partially formed by a diaphragm (11) and is limited on the shaft (3) by the shaft seals (6, 7), and that the diaphragm (11) is formed in such a way that pressure can be applied to the side facing away from the sealing fluid.