As a core control component of a vacuum system, the rationality of the internal flow channel design of the vacuum integrated valve directly affects gas flow efficiency and system pumping performance. In a vacuum environment, gas molecules are scarce and have high degrees of freedom of movement. Defects in the flow channel design can easily lead to gas adsorption, stagnation, or even backflow, thus reducing pumping efficiency. Therefore, it is necessary to optimize the design from multiple dimensions, including flow channel geometry, surface treatment, material selection, and dynamic control, to reduce gas adsorption and improve overall system performance.
Optimizing the flow channel geometry is the primary step in reducing gas adsorption. Traditional right-angle or acute-angle turns in flow channel design easily create gas stagnation zones, increasing the risk of adsorption. By adopting a flow channel design with rounded transitions or a large radius of curvature, energy loss at turns can be reduced, decreasing the frequency of collisions between molecules and the flow channel walls, thereby suppressing adsorption. Furthermore, the uniformity of the flow channel cross-section is also crucial. Abrupt changes in the cross-section (such as sudden contraction or expansion) can trigger local eddies, causing gas molecules to deposit in low-velocity regions. Therefore, the flow channel should maintain a gradual change in cross-section to ensure the continuity and stability of gas flow.
Surface treatment technology for flow channels plays a significant role in reducing gas adsorption. In a vacuum environment, the surface roughness, chemical activity, and efflux rate of materials directly affect the adsorption behavior of gas molecules. Precision polishing or electrochemical polishing processes can reduce the surface roughness of flow channels to the sub-micron level, decreasing molecular attachment points. Simultaneously, using materials with low efflux rates (such as stainless steel, ceramics, or special coatings) can suppress gas release from the material itself, preventing contamination of the vacuum environment. For ultra-high vacuum systems, surface coating technologies (such as gold, silver, or oxygen-free copper plating) can further reduce the surface adsorption rate and improve the airtightness of the flow channels.
Material selection must balance mechanical properties and vacuum adaptability. Flow channel materials for vacuum integrated valves need to possess high strength, corrosion resistance, and low permeability to withstand high pressure differentials and corrosive gases. Stainless steel is the mainstream choice due to its excellent overall performance, while aluminum alloys are suitable for weight-sensitive applications due to their lightweight advantage. For special operating conditions (such as high-temperature or highly corrosive environments), ceramics or composite materials can be used, leveraging their non-metallic properties to reduce gas adsorption and chemical reactions. Furthermore, the compatibility of the material's coefficient of thermal expansion must be considered to avoid channel deformation or seal failure due to temperature changes.
Dynamic control strategies can further improve channel efficiency. By integrating pressure sensors and flow control valves, gas pressure and velocity within the channel can be monitored in real time, and valve openings can be dynamically adjusted to optimize gas flow. For example, a large opening can be used for rapid venting at the initial stage of evacuation, switching to a smaller opening for finer control after the pressure decreases. This shortens evacuation time and avoids excessive compression and adsorption of gas within the channel. Additionally, a pulsed evacuation mode can disrupt the adsorption balance of gas molecules, promoting the desorption and discharge of adsorbed gases.
Integrated channel layout design reduces system complexity and leakage risk. In traditional vacuum systems, multiple independent valves are connected by pipes, easily creating lengthy channels and potential leakage points. Vacuum integrated valves, by integrating multiple functional units (such as shut-off valves, regulating valves, and check valves) into a single valve body, can significantly shorten channel length and reduce connection interfaces. This compact design not only reduces the gas adsorption area but also improves system reliability by reducing the number of welds and sealing rings.
Simulation analysis and experimental verification are crucial methods for optimizing the design. Computational fluid dynamics (CFD) simulations can model the gas flow state within the channel, identify high-adsorption-risk areas, and optimize the channel shape. For example, simulation results show that the guide structure at the channel inlet can significantly reduce eddies formed by gas impact, thereby reducing adsorption. Simultaneously, vacuum baking experiments can verify the outgassing rate and adsorption performance of the channel material, providing data support for material selection and surface treatment.
The internal channel design of a vacuum integrated valve requires a multi-dimensional approach involving geometric optimization, surface treatment, material selection, dynamic control, integrated layout, and simulation verification to effectively reduce gas adsorption and improve system pumping efficiency. These design strategies are not only applicable to conventional vacuum systems but can also provide a reference for valve design under special operating conditions such as ultra-high vacuum, corrosive gases, or extreme temperatures, driving vacuum technology towards higher performance and reliability.
