A diffusion pump

Abstract

The application provides a diffusion pump, and relates to the technical field of vacuum pumps. The diffusion pump comprises a shell assembly, an N-stage oil groove and a heating assembly. The shell assembly is configured with a diffusion cavity and a volatilization cavity in a first direction. The N-stage oil groove is arranged in the volatilization cavity, and is configured to accommodate oil. The heating assembly is configured to heat the oil in the N-stage oil groove to volatilize the oil, and make the volatilized oil flow to the diffusion cavity in the opposite direction of the first direction. The volatilized oil condenses in the diffusion cavity and then falls back to the volatilization cavity in the first direction. The first direction is the axial direction of the shell assembly, and the first direction points from the diffusion cavity to the volatilization cavity. The diffusion pump is provided with the N-stage oil groove, and the heating assembly is used to heat the N-stage oil groove alone, which is beneficial to improving the heating efficiency and the diffusion state of the oil.

Description

Technical Field

[0001] This application relates to the field of diffusion pump technology, and more particularly to a diffusion pump. Background Technology

[0002] As a high-vacuum pump, the core working principle of a diffusion pump is to transfer the momentum of gas molecules through a high-speed, directional vapor jet, transporting the gas from the high-vacuum end to the low-vacuum end, and then discharging it through the backing pump. During this process, the working medium (usually oil) inside the diffusion pump is heated and evaporated. The resulting oil vapor expands and accelerates in the pump body's nozzle system, forming a supersonic jet with a specific direction and velocity. If the heat source is insufficient, the formation of the high-speed vapor jet will be affected, thus reducing the pumping efficiency.

[0003] The bottom of the existing diffusion pump casing is used to hold the oil, and a heating element is installed on the outside of the casing, near the bottom, to heat the oil at the bottom. This heating method is not only slow, but also prone to localized overheating and oil carbonization due to uneven heating. Once carbon deposits adhere to the inner wall of the diffusion pump, they further affect the circulation and recycling of the oil, causing the diffusion pump to operate for a longer period before reaching its operating standards, thus significantly increasing energy consumption. Summary of the Invention

[0004] This application provides a diffusion pump that can effectively maintain the diffusion state of oil while improving heating efficiency.

[0005] To achieve the above objectives, the embodiments of this application adopt the following technical solutions: This application provides a diffusion pump, including: A shell assembly having a diffusion cavity and a volatilization cavity; An N-stage oil tank, located in the evaporation chamber, is configured to contain oil; and A heating assembly is configured to heat the oil in the N-stage oil tank to cause the oil to evaporate, and to cause the evaporated oil to flow in the opposite direction of a first direction to the diffusion chamber, and the evaporated oil to condense in the diffusion chamber and then fall back to the evaporation chamber in the first direction. The first direction is the axial direction of the shell assembly, and the first direction points from the diffusion cavity to the evaporation cavity.

[0006] In one embodiment, along the first direction, the N-level oil tank has at least two levels, and in two adjacent oil tanks, the N-level oil tank can receive the oil overflowing from the (N-1)-level oil tank.

[0007] In one embodiment, the N-level oil tank has a stepped structure such that, along the first direction, the N-level oil tank at least partially corresponds to the side of the oil overflowing from the (N-1)-level oil tank.

[0008] In one embodiment, the (N-1)th stage oil tank overflows the oil on the side closer to the reference axis; Along the first direction, the radial dimension of the contour of the Nth level oil groove on the side near the reference axis is smaller than the radial dimension of the contour of the (N-1)th level oil groove on the side near the reference axis. The reference axis is the axis of the shell assembly.

[0009] In one embodiment, the N-level oil groove is disposed on the shell assembly, and the radial dimension of the inner wall of the shell assembly gradually decreases along the first direction, such that the radial dimension of the N-level oil groove on the side away from the reference axis is smaller than the radial dimension of the (N-1)-level oil groove on the side away from the reference axis, and the radial dimension of the N-level oil groove on the side away from the reference axis is larger than the radial dimension of the (N-1)-level oil groove on the side closer to the reference axis.

[0010] In one embodiment, the Nth stage oil tank includes: The bottom wall is connected to the shell assembly and is provided continuously or intermittently along the circumference of the shell assembly. The sidewall is connected to the bottom wall, and the sidewall, the bottom wall and the shell assembly form an oil tank for containing oil.

[0011] In one embodiment, the heating component is a magnetic induction heating element.

[0012] In one embodiment, the heating assembly includes: A coil, fitted onto the housing assembly, is configured to generate a magnetic field when energized; An induction heating element is disposed in each stage of the N-stage oil tank, and the induction heating element is configured to generate heat under the action of the magnetic field to heat the oil.

[0013] In one embodiment, the heating assembly further includes: Thermal insulation material is disposed between the coil and the shell assembly, and the thermal insulation material is configured to insulate the evaporation chamber.

[0014] In one embodiment, the diffusion pump further includes: An oil circulation mechanism, one end of which is connected to the side of the evaporation chamber away from the diffusion chamber, and is used to discharge the oil at the bottom of the evaporation chamber; The other end of the oil circulation mechanism is connected to the side of the evaporation chamber near the diffusion chamber, and / or the other end of the oil circulation mechanism is connected to the evaporation chamber. The oil circulation mechanism is configured to supply oil to the diffusion chamber and / or the evaporation chamber so that the oil flows to the N-stage oil tank.

[0015] In one embodiment, the oil circulation mechanism includes: First oil storage tank; The first connecting pipe has one end connected to the side of the evaporation chamber away from the diffusion chamber, and the other end connected to the first oil storage tank. The first connecting pipe protrudes from the shell assembly at a preset height in the evaporation chamber so that when the oil level in the evaporation chamber is higher than the preset height, the oil above the preset height flows into the first oil storage tank.

[0016] In one embodiment, the oil circulation mechanism further includes: A first oil supply assembly is configured to supply oil from the first oil storage tank to the evaporation chamber and / or the diffusion chamber when the oil level in the N-stage oil tank decreases, so that at least a portion of the oil is supplied to the N-stage oil tank. And / or, when the first oil supply assembly is configured to require cooling oil, it supplies oil from the first oil reservoir to the evaporation chamber and / or the diffusion chamber, so that at least a portion of the oil is supplied to the N-stage oil tank.

[0017] In one embodiment, the first oil supply assembly includes: A pump body configured to draw oil from the first oil storage tank; The second connecting pipe has one end connected to the discharge end of the pump body and the other end connected to the evaporation chamber and / or the diffusion chamber. The second connecting pipe is provided with a first oil outlet, which faces the inner wall of the shell assembly and discharges oil.

[0018] In one embodiment, the diffusion pump further includes a nozzle, the second connecting pipe further includes a second oil outlet configured to discharge oil to the nozzle, and the first oil supply assembly further includes: A first valve body is configured to allow oil to flow from the second connecting pipe through the first oil outlet, or the first valve body is configured to allow oil to flow from the second connecting pipe through the second oil outlet.

[0019] In one embodiment, the oil circulation mechanism further includes a second oil supply assembly, the second oil supply assembly comprising: The second oil tank has its outlet end selectively connected to the diffusion cavity. When the outlet end of the second oil tank is connected to the diffusion cavity, the second oil tank is configured to discharge oil to the inner wall of the shell assembly so that the oil flows to the N-stage oil tank. The second valve body is located at the liquid outlet of the second oil tank. The second valve body is configured to control the connection or disconnection between the liquid outlet of the second oil tank and the evaporation chamber. A third valve body is located at the inlet end of the second oil tank, and the third valve body is configured to control the opening or closing of the inlet end of the second oil tank. When the second oil supply assembly is working, the third valve body opens to supply oil to the second oil tank. After the second oil tank is full of oil, the third valve body closes and the second valve body opens to replenish the oil in the second oil tank to the N-stage oil tank.

[0020] In one embodiment, the oil circulation mechanism further includes an oil discharge assembly, which includes: The third oil storage tank, wherein the inlet end of the third oil storage tank is selectively connected to the first oil storage tank; The fourth valve body is located at the inlet end of the third oil tank and is configured to control the connection or disconnection between the inlet end of the third oil tank and the first oil tank. The fifth valve body is located at the liquid outlet end of the third oil storage tank for opening or closing; When the drain assembly is working, the fourth valve opens to drain the oil in the first oil tank into the third oil tank; after the oil in the first oil tank has been drained to a preset capacity, the fourth valve closes and the fifth valve opens to drain the oil in the third oil tank.

[0021] As can be seen from the above technical solutions, the embodiments of this application have at least the following beneficial effects: The diffusion pump provided in this application includes a housing assembly, an N-stage oil tank, and a heating assembly. The housing assembly has a diffusion chamber and a evaporation chamber along a first direction. The N-stage oil tank is located in the evaporation chamber and is configured to contain oil. The heating assembly is configured to heat the oil in the N-stage oil tank, causing the oil to evaporate and flow in the opposite direction to the diffusion chamber. The evaporated oil condenses in the diffusion chamber and then falls back into the evaporation chamber. This design eliminates the traditional heating method of setting a heater at the bottom of the housing. Since the heating amount of each stage of the oil tank is less than the heating of the entire bottom surface, the heating efficiency is improved, thereby improving the diffusion state of the oil. This direct heating method can significantly reduce heat loss during the heat transfer process, allowing the oil to reach the evaporation temperature more quickly, thus effectively shortening the start-up time of the diffusion pump and improving its working efficiency.

[0022] It should be understood that the descriptions of technical features, technical solutions, beneficial effects, or similar language in the embodiments of this application do not imply that all features and advantages can be achieved in any single embodiment. Rather, it is understood that the description of a feature or beneficial effect means that a specific technical feature, technical solution, or beneficial effect is included in at least one embodiment. Therefore, the descriptions of technical features, technical solutions, or beneficial effects in this specification do not necessarily refer to the same embodiment. Furthermore, the technical features, technical solutions, and beneficial effects described in this embodiment can be combined in any suitable manner. Those skilled in the art will understand that embodiments can be implemented without one or more specific technical features, technical solutions, or beneficial effects of a particular embodiment. In other embodiments, additional technical features and beneficial effects may be identified in specific embodiments that do not embody all embodiments. Attached Figure Description

[0023] Figure 1 A schematic diagram of a diffusion pump provided in an embodiment of this application in one specific embodiment; Figure 2 for Figure 1 A schematic diagram of the internal structure of the Chinese embodiment; Figure 3 for Figure 2 A schematic diagram of a medium-N grade oil tank in one specific embodiment; Figure 4 A schematic diagram of the diffusion pump provided in this application embodiment in another specific embodiment; Figure 5 for Figure 2 A magnified view of a section at point A in the middle; Figure 6 A schematic diagram of the diffusion pump provided in this application embodiment in another specific embodiment; Figure 7 for Figure 2 A magnified view of a section at point B.

[0024] Figure label: 1000-Diffusion Pump; 100 - Shell assembly; 110 - Diffusion chamber; 120 - Evaporation chamber; 130 - First inner shell; 140 - First outer shell; 150 - Condensation chamber; 200 - N-level oil tank; 210 - First-level oil tank; 220 - Second-level oil tank; 230 - Third-level oil tank; 240 - Bottom wall; 250 - Side wall; 300 - Heating element; 310 - Coil; 320 - Induction heating element; 330 - Insulation cotton; 400 - Liquid circulation mechanism; 410 - First oil reservoir; 411 - Liquid level sensor; 420 - First connecting pipe; 430 - First oil supply assembly; 431 - Pump body; 432 - Second connecting pipe; 433 - First outlet; 434 - Second oil outlet; 435 - First valve body; 440 - Second oil supply assembly; 441 - Second oil reservoir; 442 - Second valve body; 443 - Third valve body; 450 - Oil discharge assembly; 451 - Third oil reservoir; 452 - Fourth valve body; 453 - Fifth valve body; 500 - Nozzle; 600 - Condenser assembly; 610 - Condenser tube. Detailed Implementation

[0025] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0026] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0027] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0030] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0031] This application provides a diffusion pump, such as Figure 1 As shown, the diffusion pump 1000 includes a housing assembly 100 and a nozzle 500. It also includes an N-stage oil tank 200 and a heating assembly 300. The housing assembly 100 serves as the main support structure of the diffusion pump, providing a stable installation space for the N-stage oil tank 200 and the heating assembly 300. The heating assembly 300 provides a sufficient heat source for the oil in the N-stage oil tank 200, causing the oil to be heated and generate low-pressure steam, which diffuses into the interior of the housing assembly 100.

[0032] The first direction is the top-down direction.

[0033] The diffusion pump 1000 is a high vacuum pump, typically suitable for 10... -1 Up to 10 -7In a vacuum range of Pa, the diffusion pump 1000 cannot be started directly from atmospheric pressure and requires a mechanical pump as a backing pump for initial evacuation. Its core working principle is to transfer the momentum of gas molecules through a high-speed, directional flow of vapor jet, transporting the gas from the high vacuum end to the low vacuum end, and then discharging it through the backing pump.

[0034] In addition, the diffusion pump 1000 also includes a nozzle 500 disposed in the diffusion chamber 110. The shell assembly 100 is constructed with a diffusion chamber 110 and a volatilization chamber 120 along a first direction. The volatilization chamber 120 contains oil. The heating assembly 300 heats the oil to volatilize the oil and generate low-pressure steam. The steam flows in the opposite direction of the first direction to the diffusion chamber 110 and is ejected step by step through the nozzle 500. After the gas molecules collide with the steam molecules, they gain momentum and move along the steam flow direction in the first direction. Subsequently, they cool and condense on the inner wall of the vacuum chamber of the shell assembly 100 and flow back to the oil pot to form a cycle.

[0035] The diffusion pump 1000 also includes a condenser assembly 600. The condenser assembly 600 is located in the housing assembly 100 and is configured to cool the oil within the diffusion chamber 110, condensing the gaseous oil into a liquid state. The condenser assembly 600 absorbs heat from the inner wall of the diffusion chamber 110 through heat exchange, thereby lowering the internal temperature of the diffusion chamber 110. As a result, oil molecules that are gaseous within the diffusion chamber 110, upon contact with the cooler inner wall of the diffusion chamber 110 or under the direct action of the condenser assembly 600, rapidly release heat and transform from a gaseous state into liquid oil droplets. These liquid oil droplets then drip back down under gravity and collect in the evaporation chamber 120, thereby reducing oil loss and helping to maintain a stable operating pressure and temperature environment within the diffusion chamber.

[0036] like Figure 2 As shown, the shell assembly 100 is constructed with a diffusion chamber 110 and a evaporation chamber 120. An N-stage oil tank 200 is disposed in the evaporation chamber 120 and is configured to contain oil. The heating assembly 300 is configured to heat the oil in the N-stage oil tank 200 to cause the oil to evaporate, and the evaporated oil flows in the opposite direction to the diffusion chamber 110 in a first direction. After condensing in the diffusion chamber 110, the evaporated oil falls back to the evaporation chamber 120 in the first direction. The first direction is the axial direction of the shell assembly 100, and the first direction points from the diffusion chamber 110 to the evaporation chamber 120.

[0037] The diffusion chamber 110 and the evaporation chamber 120 are interconnected, forming a sealed cavity. During operation, this sealed wall acts as a vacuum chamber, with a pressure reaching 10. -1 Up to 10 -5Pa. This high vacuum environment provides the necessary conditions for oil evaporation and directional vapor flow, effectively avoiding interference from external gas molecules on the vapor flow and ensuring that oil vapor can circulate efficiently within the housing assembly 100 according to the designed path. At the same time, the sealed vacuum chamber design also ensures the vacuum stability of the diffusion pump 1000 during operation, laying the foundation for achieving high vacuum pumping performance.

[0038] In this embodiment, the diffusion pump 1000 structure eliminates the traditional method of using the bottom of the housing to hold the oil and placing a heating element on the outside of the housing, near the bottom, to heat the oil at the bottom. Instead, it employs an N-stage oil tank 200 structure, with the heating element directly heating the N-stage oil tank 200. This N-stage oil tank 200 structure allows for the storage of oil of the same volume in N stages, facilitating heating in units and reducing the volume of oil to be heated in each heating unit. Since the heating amount of each stage is less than the heating of the entire bottom surface, heating efficiency is improved. This heating method significantly reduces heat loss during heat transfer, allowing the oil to reach its evaporation temperature more quickly, thereby effectively shortening the start-up time of the diffusion pump 1000 and improving its operating efficiency.

[0039] Meanwhile, this heating method has a fast heating speed, avoiding problems such as local overheating and oil carbonization pollution caused by slow heating speed in related technologies. This reduces the adhesion of oil carbon deposits on the inner wall of the diffusion pump 1000 and the nozzle 500, which helps to improve the circulation and recovery rate of oil, increase the operating time of the diffusion pump 1000, and reduce energy consumption.

[0040] In related technologies, the oil heating of a diffusion pump usually takes 2 to 3 hours to enter normal working condition. However, in this embodiment, the oil is contained in the N-level oil tank 200. After experimentation, heating for 1.5 to 3 minutes is sufficient for the diffusion pump 1000 to enter normal working condition, which significantly reduces the heating time, improves the heating efficiency of the diffusion pump 1000, and reduces energy consumption.

[0041] In one embodiment, along the first direction, the N-level oil tank 200 has at least two levels. In two adjacent levels, the N-level oil tank 200 can receive the oil overflowing from the (N-1)-level oil tank. With this design, it is not necessary to inject oil into each level of the oil tank separately. Oil only needs to be injected into the topmost first-level oil tank 210. When the first-level oil tank 210 is full, the oil will naturally overflow to the next level, the second-level oil tank 220, and so on. The N-level oil tank 200 can be filled with oil step by step through overflow, thereby simplifying the oil injection process and improving the efficiency of oil injection.

[0042] like Figure 3As shown, exemplarily, the N-level oil tank 200 is a three-level oil tank, specifically including a first-level oil tank 210, a second-level oil tank 210, and a third-level oil tank 230. The first-level oil tank 210, the second-level oil tank 210, and the third-level oil tank 230 are arranged sequentially along a first direction. When oil is injected, after the first-level oil tank 210 is full, the oil overflows and flows to the second-level oil tank 220. After the second-level oil tank 220 is full, the oil flows to the third-level oil tank 210, thus achieving top-down, step-by-step injection. This structure only needs to supply oil to the uppermost first-level oil tank 210 through a single oil inlet to achieve automatic filling of the three-level oil tank using the oil's own gravity.

[0043] In one embodiment, the N-level oil tank 200 has a stepped structure, such that along the first direction, the N-level oil tank at least partially corresponds to the side of the overflowing oil from the (N-1)-level oil tank. This stepped layout allows for precise alignment of the overflow sidewall of the upper-level oil tank with the lower-level oil tank, ensuring a smooth and leak-free transition of oil from the higher-level to the lower-level oil tank during overflow. In this embodiment, the overflow sidewall of the first-level oil tank 210 corresponds to the opening of the second-level oil tank 220, so that the second-level oil tank 220 receives the oil from the first-level oil tank 210; similarly, the overflow sidewall of the second-level oil tank 220 corresponds to the third-level oil tank 230, so that the third-level oil tank 230 receives the oil from the second-level oil tank 220, achieving a step-by-step flow of oil.

[0044] By designing the N-stage oil tank in a stepped manner, the position of each stage decreases sequentially along the first direction. When the oil in the (N-1)th stage oil tank reaches the overflow condition due to continuous replenishment, the oil can smoothly overflow along the side wall of that stage oil tank and flow precisely to the lower Nth stage oil tank. This structural design ensures that the overflowing oil will not splash or deviate, but will enter the next stage oil tank in a stable liquid flow form, effectively avoiding oil waste and contamination of other internal components of the pump.

[0045] The reference axis is the axis of the housing assembly 100.

[0046] In one embodiment, oil overflows from the (N-1)th stage oil tank on the side closest to the reference axis; along the first direction, the radial dimension of the contour of the Nth stage oil tank on the side closest to the reference axis is smaller than the radial dimension of the contour of the (N-1)th stage oil tank on the side closest to the reference axis; the reference axis is the axis of the housing assembly 200. Oil flows sequentially from the first stage oil tank 210 to the third stage oil tank 230, overflowing from the side closest to the reference axis in each stage. This facilitates the sequential reception of oil in the Nth stage oil tank 200, achieving an orderly and directional flow of oil from top to bottom, ensuring the stability of the oil supply, and reducing oil loss during transmission.

[0047] In one embodiment, an N-level oil tank 200 is disposed on the housing assembly 100. Along the first direction, the radial dimension of the inner wall of the housing assembly 100 gradually decreases, such that the radial dimension of the N-level oil tank on the side away from the reference axis is smaller than the radial dimension of the (N-1)-level oil tank on the side away from the reference axis, and the radial dimension of the N-level oil tank on the side away from the reference axis is larger than the radial dimension of the (N-1)-level oil tank on the side closer to the reference axis. The radial dimension of the inner wall of the housing assembly 100 gradually decreases and can be configured as an arc-shaped tube or an inverted trapezoidal structure to facilitate the arrangement of multiple levels of oil tanks 200. Meanwhile, the structural layout of the N-stage oil tank 200 and the shell assembly 100 helps to reduce the overlap of the projected area of ​​adjacent oil tanks, thereby making fuller use of the space within the evaporation chamber 120. While ensuring improved oil heating efficiency, it also helps to maintain the oil evaporation rate of the multi-stage oil tank 200 in this embodiment within a unit time that is close to that in related technologies. Furthermore, the oil evaporation rate within a unit time can be set according to the technical requirements of the diffusion pump 1000, which helps to maintain the performance of the diffusion pump 1000, or even improve the performance of the diffusion pump 1000, based on structural improvements.

[0048] Specifically, such as Figure 3 As shown, the Nth-level oil tank includes a bottom wall 240 and a side wall 250. The bottom wall 240 is connected to the shell assembly 100 and is continuously or intermittently arranged along the circumference of the shell assembly 100. The side wall 250 is connected to the bottom wall 240, and the side wall 250, the bottom wall 240, and the shell assembly 100 together form an oil tank for containing oil.

[0049] In another embodiment, the bottom wall 240 is continuously provided along the circumference of the shell assembly 100. The continuously provided bottom wall 240 helps to improve the stability of oil overflow and reception between adjacent oil tanks, and prevents oil from flowing directly to the bottom of the evaporation chamber 120. This Nth-stage oil tank has a simple structure, is easy to process, and helps to reduce costs.

[0050] In one embodiment, the bottom wall 240 is intermittently arranged along the circumference of the shell assembly 100. Exemplarily, there are seven bottom walls 240. The bottom walls 240, side walls 210 disposed on both sides of the same bottom wall 240, and the shell assembly 100 enclose an oil tank 240 for containing oil. Side walls 250 disposed opposite each other between two adjacent bottom walls 240 and the shell assembly 100 enclose an overflow surface for oil to flow to the next level oil tank. When the oil level in the oil tank reaches the height of the overflow surface, the oil flows to the next level oil tank through the overflow surface. This intermittent bottom wall 240 structure allows the oil to overflow in an orderly manner at specific locations, further precisely controlling the flow path and flow rate of the oil between different levels of oil tanks, and avoiding uneven flow distribution problems that might result from uniform circumferential overflow of oil. Meanwhile, the overflow surface provides a clear channel for oil flow, reducing resistance and turbulence during oil flow, ensuring smooth and stable oil transfer, and thus better meeting the requirements of the diffusion pump for the oil circulation system.

[0051] In one embodiment, such as Figure 4 As shown, the shell assembly 100 includes a first inner shell 130 and a first outer shell 140. The first inner shell 130 corresponds to the diffusion cavity 110. The first outer shell 140 is sleeved on the first inner shell 130 and overlaps with the first inner shell 130. The first inner shell 130 and the first outer shell 140 are spaced apart so that a condensation cavity 150 is defined between the first inner shell 130 and the first outer shell 140. A condensation assembly 500 is disposed in the condensation cavity 150. The condensation assembly 500 is configured to cool the oil in the diffusion cavity 110 to condense the gaseous oil into a liquid state.

[0052] The existing shell assembly has a single-layer structure, leaving the condenser component exposed for extended periods. This leads to condensation and subsequent corrosion. This application employs a double-layer shell assembly 100, housing the condenser component 500 within the condensation chamber 150 between the first inner shell 130 and the first outer shell 140. This prevents contact with the outside environment, thus preventing condensation and avoiding problems such as pipe corrosion or electrical leakage caused by condensation. This improves the safety and lifespan of the diffusion pump 1000. Simultaneously, it effectively blocks external impurities from entering the condensation chamber 150, preventing contamination of the condenser component 500 or affecting its cooling efficiency. This enhances the cooling effect of the condenser component 500 and also achieves superior insulation.

[0053] In addition, the overlapping double-shell assembly 100 facilitates assembly and disassembly, which helps improve assembly and maintenance efficiency.

[0054] In one embodiment, such as Figure 4As shown, the first outer shell 140 includes a shell body 141 and a flange 142. The flange 142 is connected to the shell body 141 and is disposed near the end of the shell body 141 facing away from the first direction. The flange 142 is configured to overlap the first inner shell 130; the first direction is parallel to the axial direction of the shell assembly 100. In this embodiment, the first outer shell 140 is placed on top of the first inner shell 130, which facilitates assembly and disassembly and improves assembly and maintenance efficiency; when it is necessary to maintain the condenser assembly 500, the first outer shell 140 can be directly removed. It should be noted that the condenser chamber 150 here is not an absolute vacuum chamber.

[0055] In one embodiment, the condensing assembly 600 includes a condenser tube 610. The condenser tube is wound around the outer periphery of the first inner shell 130 and is configured to transport refrigerant. In this embodiment, the condenser tube is a hollow tubular structure and is tightly wound around the outer wall of the first inner shell 130 in a spiral or serpentine pattern, which significantly increases the contact area between the condenser tube and the first inner shell 130, thereby improving heat exchange efficiency. When the refrigerant flows inside the condenser tube, it can quickly absorb the heat transferred by the first inner shell 130, thereby effectively reducing the temperature inside the first inner shell 130 and providing a good low-temperature environment for vapor condensation inside the diffusion pump. Furthermore, this winding method makes the condenser tube layout more compact, allowing for a longer condenser tube to be arranged within the limited space of the condensing chamber 150, further enhancing the condensation effect.

[0056] In one embodiment, such as Figure 4 As shown, the shell assembly 100 also includes a second inner shell 160 and a second outer shell 170. The second inner shell 160 corresponds to the evaporation chamber 120 and is configured to contain oil. The second inner shell 160 is sealed to the first inner shell 170. An N-stage oil tank 200 is disposed on the second inner shell 160, which can contain oil overflowing from the N-stage oil tank 200. The second outer shell 170 is sleeved on the second inner shell 160 and connected to the first outer shell 170. The second outer shell 160 and the second inner shell 160 are spaced apart to form a heat-insulating cavity between the second inner shell 160 and the second outer shell 170. This helps to keep the second inner shell 160 warm and prevents the temperature of the oil heated by the heating component 300 from diffusing outward, thus saving energy.

[0057] Optionally, the second outer shell 170 is provided with a coating on the side facing the second inner shell 160. This coating may be a heat-reflective coating, thereby improving the heat preservation effect of the second outer shell 170 on the evaporation chamber 120.

[0058] In one embodiment, the size of the second inner shell 160 gradually decreases along the direction away from the first inner shell 130. The gradually decreasing size of the second inner shell 160 can be configured as an arc-shaped tube or an inverted trapezoidal structure to facilitate the installation of multi-stage oil tanks 200.

[0059] Meanwhile, the structural layout of the N-stage oil tank 200 and the shell assembly 100 helps to reduce the overlap of the projected area of ​​adjacent oil tanks, thereby making fuller use of the space within the evaporation chamber 120. While ensuring improved oil heating efficiency, it also helps to maintain the oil evaporation rate of the multi-stage oil tank 200 in this embodiment within a unit time that is close to that in related technologies. Furthermore, the oil evaporation rate within a unit time can be set according to the technical requirements of the diffusion pump 1000, which helps to maintain the performance of the diffusion pump 1000, or even improve the performance of the diffusion pump 1000, based on structural improvements.

[0060] In one embodiment, the shell assembly 100 has a square outline in a cross-section perpendicular to the first direction. With the same floor space, the square container has a larger capacity. Compared to a conventional circular cross-section shell, the square cross-section shell assembly 100 can make more efficient use of the installation space, which helps improve the overall structural stability and assembly accuracy.

[0061] In one embodiment, the heating component 300 uses magnetic induction heating. Because it's an N-stage oil tank 200 structure, if contact heating were used for each stage, a heating plate would need to be installed under each tank, resulting in a complex structure and interference with oil flow between the multiple stages of oil tanks 200. Oil might even flow onto the connecting heating wires. In this embodiment, magnetic induction heating achieves non-contact heating, effectively avoiding the localized overheating that can occur with direct contact in traditional resistance heating methods, thus heating the oil in the tank more evenly. This heating method uses electromagnetic induction to heat the oil tank itself, resulting in higher thermal efficiency, less energy loss, and rapid heating of the oil to the required operating temperature, shortening the start-up time of the diffusion pump 1000. Simultaneously, because it doesn't directly contact the oil, it reduces the risk of contamination from the heating element, helping to maintain the purity and performance stability of the oil, thereby improving the pumping efficiency and operational reliability of the diffusion pump 1000.

[0062] Specifically, such as Figure 5 As shown, the heating assembly 300 includes a coil 310 and an induction heating element 320. The coil 310 is fitted onto the housing assembly 100 and is configured to generate a magnetic field when energized. The induction heating element 320 is disposed in each stage of the N-stage oil tank 200 and is configured to generate heat under the influence of the magnetic field to heat the oil. Utilizing the magnetic field to penetrate the housing assembly 100 and directly heat the oil in the oil tank results in higher and faster heating efficiency.

[0063] Optionally, the induction heating element 320 can be placed in some or all of the oil tanks, without specific limitation. The induction heating element 320 can be made of a metal material with high magnetic permeability and high resistivity, such as stainless steel or iron-nickel alloy, to ensure that eddy currents can be efficiently generated and converted into heat energy in an alternating magnetic field.

[0064] In one embodiment, the induction heating element 320 should be disposed on the side wall 250 and / or bottom wall 240 of the N-level oil tank 200, and should not be disposed on the housing assembly 100.

[0065] Optionally, the induction heating element 320 can be disposed on a portion of the sidewall 250 or all of the sidewall 250 of the N-level oil tank 200. Alternatively, the induction heating element 320 can also be disposed on a portion of the bottom wall 240 of the N-level oil tank 200, or the induction heating element 320 can also be disposed on both the bottom wall 240 and the bottom wall 240 of the N-level oil tank 200.

[0066] like Figure 3 As shown, in this embodiment, the induction heating element 320 is disposed on the bottom wall 240 of the first-stage oil tank 210. In one embodiment, if the induction heating element 320 is installed on the side wall 250 of the N-stage oil tank 200, it can be fixedly connected to the side wall 250 by embedding or welding to ensure sufficient contact with the oil and improve heat exchange efficiency. In another embodiment, the induction heating element 320 should be disposed on part of the bottom wall 240 of the N-stage oil tank 200. Depending on the area and shape of the bottom wall 240, the induction heating element 320 can be designed as a suitable plate or ring structure to increase the heating area and allow heat to be transferred to the oil more evenly. In another embodiment, the induction heating element 320 should be disposed on both the side wall 250 and the bottom wall 240 of the N-stage oil tank 200 to increase the heating area and achieve better heating effect.

[0067] In one embodiment, the induction heating element 320 is made of a magnetic induction material, preferably a high magnetic induction material, such as iron, low carbon steel, silicon steel sheet or iron-nickel alloy, etc. These materials are easily magnetized, have high magnetic flux and large hysteresis loss.

[0068] It should be emphasized that the induction heating element 320 must not be installed on the housing assembly 100. This not only effectively avoids the risk of welding leakage that may be caused by installation on the housing assembly 100, but also allows the induction heating element 320 to heat the oil more directly, reducing heat loss during the heat transfer process and further optimizing the heating performance of the diffusion pump.

[0069] For example, the outer shell of the shell assembly 100 inside the evaporation chamber 120 is made of a weak magnetic induction material, which allows the magnetic field to penetrate smoothly, and the shell itself generates less heat, thereby ensuring that the outer wall is not hot to the touch and is safe to use.

[0070] In one embodiment, the heating assembly 300 further includes insulation cotton 330, which is configured to insulate the evaporation chamber 120. The insulation cotton 330 is disposed between the coil 310 and the shell assembly 100. The main purpose of the insulation cotton 330 is to reduce heat loss to the shell assembly 100, thereby further improving heating efficiency and reducing energy consumption. Specifically, the insulation cotton 330 forms an effective thermal barrier between the outer coil 310 and the shell assembly 100. When the coil 310 operates and generates electromagnetic induction, thereby causing the induction heating element 320 to heat up, some heat may be transferred to the outside of the coil 310 through radiation or conduction. At this time, the insulation cotton 330, with its excellent thermal insulation properties, can significantly block this heat transfer to the shell assembly 100, avoiding unnecessary heat waste. In actual installation, the insulation cotton 330 should be tightly fitted to the outer surface of the coil 310 and form a stable fill between it and the inner wall of the shell assembly 100 to ensure its full thermal insulation effect. The selection of materials usually takes into account high temperature resistance, thermal insulation coefficient and chemical stability, in order to adapt to the working environment inside the diffusion pump.

[0071] In one embodiment, such as Figure 2 As shown, the diffusion pump 1000 also includes an oil circulation mechanism 400. One end of the oil circulation mechanism 400 is connected to the side of the evaporation chamber 120 away from the diffusion chamber 110 and is used to discharge the oil at the bottom of the evaporation chamber 120; the other end of the oil circulation mechanism 400 is connected to the evaporation chamber 120, and the oil circulation mechanism 400 is configured to supply oil to the evaporation chamber 120 and / or the diffusion chamber 110 so that the oil flows to the N-stage oil tank 200.

[0072] In this embodiment, the oil circulation mechanism 400 connects the evaporation chamber 120 and the diffusion chamber 110, continuously supplying oil to the evaporation chamber 120 to ensure that there is always sufficient oil in the N-stage oil tank 200 for heating and evaporation, thereby maintaining the stable operation of the diffusion pump. Specifically, after the oil in the evaporation chamber 120 is heated and evaporated by the induction heating element 320 and participates in the pumping process, the oil that has not completely evaporated or condensed and flowed back will accumulate at the bottom of the evaporation chamber. The oil circulation mechanism 400 can extract this accumulated oil from the evaporation chamber 120, pump it into the diffusion chamber 110 in a timely manner, and then return it to the evaporation chamber 120 through the diffusion chamber 110, realizing the recycling of oil. This "bottom-in, top-out" oil circulation method not only reduces oil consumption and lowers operating costs, but also avoids the impact of excessive oil impurities on the pumping performance and service life of the diffusion pump. Meanwhile, by precisely controlling the flow rate and pressure of the oil supplied to the evaporation chamber 120 by the oil circulation mechanism 400, it can be ensured that the oil can flow evenly and stably to each level of the N-level oil tank 200, meeting the different oil volume requirements of each level of the oil tank, and further improving the overall working efficiency and reliability of the diffusion pump.

[0073] In one embodiment, such as Figure 5 As shown, the oil circulation mechanism 400 includes a first oil storage tank 410 and a first connecting pipe 420. One end of the first connecting pipe 420 is connected to the side of the evaporation chamber 120 away from the diffusion chamber 110, and the other end is connected to the first oil storage tank 410. The first connecting pipe 420 protrudes from the shell assembly 100 in the evaporation chamber 120 by a preset height H, so that when the oil level in the evaporation chamber 120 is higher than the preset height, the oil above the preset height flows into the first oil storage tank 410.

[0074] During operation, once the N-stage oil tank is full, the oil in the last-stage oil tank can overflow to the bottom of the shell assembly 100. The first connecting pipe 420 protrudes from the shell assembly 100 at a preset height H within the evaporation chamber 120, ensuring that the maximum oil level that the bottom of the shell assembly 100 can hold is the preset height H. When the oil level at the bottom of the shell assembly 100 exceeds the preset height H, the oil at the bottom of the shell assembly 100 overflows through the first connecting pipe 420 and flows directly back into the first oil storage tank 410. Furthermore, during this process, no external power is required to extract the oil, which helps save energy.

[0075] In one embodiment, the oil circulation mechanism 400 further includes a first oil supply assembly 430. The first oil supply assembly 430 is configured to supply oil from the first oil reservoir 410 to the evaporation chamber 120 and / or the diffusion chamber 110 when the oil level in the N-stage oil tank 200 decreases, so that at least a portion of the oil is supplied to the N-stage oil tank 200; and / or, the first oil supply assembly 430 is configured to supply oil from the first oil reservoir 410 to the evaporation chamber 120 and / or the diffusion chamber 110 when cooling of the oil is required, so that at least a portion of the oil is supplied to the N-stage oil tank 200.

[0076] When it is necessary to replenish the N-level oil tank 200 with oil, the first oil supply component 430 can be activated to transport the oil in the first oil storage tank 410 to the evaporation chamber 120 and / or the diffusion chamber 110, and inject it into the N-level oil tank 200.

[0077] When cooling is required for the N-stage oil tank 200, the first oil supply component 430 can be activated to deliver oil from the first oil storage tank 410 to the evaporation chamber 120 and / or the diffusion chamber 110, thereby gradually replacing the oil in the multi-stage oil tank and allowing it to flow out from the bottom, achieving rapid cooling. Existing technologies require shutdown for cooling, with each cooling cycle taking 2-3 hours. In this application, a cooling cycle can be achieved in 1.5-3 minutes. For example, this cooling is not to room temperature, but to below 35 degrees Celsius.

[0078] Of course, starting the first oil supply component 430 can not only transport the oil in the first oil storage tank 410 to the evaporation chamber 120 and / or the diffusion chamber 110, increasing the amount of oil in the N-stage oil tank 200, but also cool the N-stage oil tank 200.

[0079] Specifically, the first oil supply assembly 430 includes a pump body 431 and a second connecting pipe 432. The pump body 431 is configured to draw oil from the first oil storage tank 410; one end of the second connecting pipe 432 is connected to the discharge end of the pump body 431, and the other end is connected to the diffusion chamber 110 and / or the evaporation chamber 120. The second connecting pipe 432 is provided with a first oil outlet 433, which faces the inner wall of the shell assembly 100 to discharge oil. This design allows the oil sprayed from the first oil outlet 433 to act directly on the inner wall of the shell assembly 100. With the guidance and dispersion effect of the inner wall, the oil is more evenly distributed and flows downward by gravity, so that when flowing through the N-stage oil tanks 200, each stage of the oil tank can more efficiently draw the required amount of oil from the oil adhering to the wall. The pump body 431, which serves as the power source, directly determines the delivery pressure and flow rate of the oil by its pumping and pressurizing capabilities. This ensures that the oil overcomes system resistance and smoothly completes the circulation path from the first oil storage tank 410 to the diffusion chamber 110 and then to the evaporation chamber 120, thus preventing excessive turbulence or stagnation of the oil in the pipe, which would affect the smoothness and uniformity of the oil supply.

[0080] In one embodiment, such as Figure 1 As shown, the diffusion pump 1000 also includes a nozzle 500. (As...) Figure 6 As shown, the second connecting pipe 432 further includes a second oil outlet 434, which is configured to discharge oil to the nozzle 500. The first oil supply assembly 430 also includes a first valve body 435, which is configured to allow oil to be discharged from the second connecting pipe 432 through the first oil outlet 433, or, allow oil to be discharged from the second connecting pipe 432 through the second oil outlet 434.

[0081] Optionally, the first valve body 435 is a three-way valve with a built-in single-set magnetic switch, which can selectively block one set of oil circuits while simultaneously opening another set of oil circuits. In this embodiment, as... Figure 7 As shown, the first valve body 435 has a valve cavity inside, and the valve body wall has a first port E, a second port F, and a third port G that communicate with the valve cavity. The first port E is connected to the first oil outlet 433, the second port F is connected to the second oil outlet 434, and the third port G is connected to the second connecting pipe 432. A single set of magnetically controlled switches is slidably and reversibly mounted on the shared medium reversing passage of the third port G, the first port E, and the second port F. It can switch its overall position according to an external magnetic drive signal, selectively blocking one branch passage while simultaneously opening another branch passage. Under normal conditions, the single set of magnetically controlled switches maintains a preset normally closed reference position, forming an initial blocking seal limit for the overall reversing passage.

[0082] For example, such as Figure 7 As shown, when an external magnetic drive signal triggers the magnetic switch to move towards the second port F, the sealing end of the magnetic switch blocks the branch passage where the first port E is located. At this time, the third port G and the second port F are connected, and the oil from the second connecting pipe 432 can enter the valve chamber through the third port G, and then flow to the second oil outlet 434 through the second port F, ultimately supplying oil to the nozzle 500. Conversely, when the external magnetic drive signal changes, causing the magnetic switch to move towards the first port E, its sealing end blocks the branch passage where the second port F is located. At this time, the third port G and the first port E are connected, and the oil flows to the first oil outlet 433 through the third port G and the first port E, thereby supplying oil to the inner wall of the housing assembly 100. This single-set magnetic switch design can quickly switch the oil circuit through simple magnetic drive. It has a compact structure and sensitive response, effectively ensuring the selectivity and reliability of oil supply to the inner wall of the housing assembly 100 and the nozzle 500 under different working conditions.

[0083] In one embodiment, such as Figure 6 As shown, the oil circulation mechanism 400 also includes a second oil supply assembly 440, which includes a second oil reservoir 441, a second valve body 442, and a third valve body 443. The outlet end of the second oil reservoir 441 is selectively connected to the diffusion chamber 110. When the outlet end of the second oil reservoir 441 is connected to the diffusion chamber 110, the second oil reservoir 441 is configured to discharge oil to the inner wall of the housing assembly 100 to replenish the oil in the second oil reservoir 441 to the N-stage oil tank 200.

[0084] The second valve body 442 is located at the outlet end of the second oil tank 441, and is configured to control the connection or disconnection between the outlet end of the second oil tank 441 and the diffusion chamber 110. The third valve body 443 is located at the inlet end of the second oil tank 441, and the second valve body 442 is configured to control the opening or closing of the inlet end of the second oil tank 441. When the second oil supply assembly 440 is working, the third valve body 443 opens to supply oil to the second oil tank 441. After the second oil tank 441 is full of oil, the third valve body 443 closes, and the second valve body 442 opens to replenish oil to the N-stage oil tank 200. Only in this way can the vacuum be avoided during the refueling process.

[0085] The external oil is quickly injected into the diffusion pump 1000 via the second oil supply component 440, thus replenishing the oil more quickly.

[0086] Meanwhile, the first oil supply component 430 and the second oil supply component 440 work together to realize online oil supply and oil change operations of the equipment, and complete online oil change without stopping the machine without damaging the vacuum environment; at the same time, the generation of carbon deposits and impurities is reduced by oil circuit flushing - the new oil flushes the carbon deposits and impurities attached to the inner wall of the oil circuit during the flow process, reducing the problems of oil circuit blockage and reduced heat transfer efficiency caused by impurity accumulation, and further ensuring the long-term stable operation of the pump body.

[0087] Specifically, a liquid level sensor 411 is installed in the first oil tank 410 and / or the second oil tank 441 to monitor the liquid level in the oil tank in real time. When the liquid level is lower than the preset lower limit, the liquid level sensor will immediately send a signal to the control system, and the control system will then start the first oil supply component 430 to replenish the liquid, or start the second oil supply component 440 to replenish or cool the N-stage oil tank 200.

[0088] In one embodiment, the oil circulation mechanism further includes an oil discharge assembly 450. The oil discharge assembly 450 includes a third oil reservoir 451, a fourth valve body 452, and a fifth valve body 453. The inlet end of the third oil reservoir 451 is selectively connected to the first oil reservoir 410; the fourth valve body 452 is located at the inlet end of the third oil reservoir 451 and is configured to control the connection or disconnection between the inlet end of the third oil reservoir 451 and the first oil reservoir 410; the fifth valve body 453 is located at the outlet end of the third oil reservoir 451 and is open or closed. When the oil discharge assembly is working, the fourth valve body 452 opens to discharge the oil in the first oil reservoir 410 into the third oil reservoir 451; after a preset capacity of oil has been discharged from the first oil reservoir 410, the fourth valve body 452 closes and the fifth valve body 453 opens to discharge the oil in the third oil reservoir 451. The fourth valve body 452 and the fifth valve body 453 work alternately to ensure the internal vacuum level.

[0089] The oil drain assembly 450 enables the diffusion pump 1000 to perform large-scale oil changes or drain old oil efficiently and conveniently, avoiding problems such as oil residue and cumbersome operation that may occur in traditional oil draining methods, and further improving the convenience and reliability of equipment maintenance.

[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A diffusion pump, characterized in that, include: The shell assembly (100) is configured with a diffusion cavity (110) and a volatilization cavity (120). An N-level oil tank (200) is provided in the evaporation chamber (120), and the N-level oil tank (200) is configured to contain oil. as well as Heating assembly (300) is configured to heat the oil in the N-stage oil tank (200) to cause the oil to evaporate, and cause the evaporated oil to flow in the opposite direction of the first direction to the diffusion chamber (110), and after condensing in the diffusion chamber (110), the evaporated oil falls back to the evaporation chamber (120) in the first direction. The first direction is the axial direction of the shell assembly (100), and the first direction is from the diffusion cavity (110) to the evaporation cavity (120).

2. The diffusion pump according to claim 1, characterized in that, Along the first direction, the N-level oil tank (200) is at least two-level, and in two adjacent oil tanks, the N-level oil tank can receive the oil overflowing from the N-1-level oil tank.

3. The diffusion pump according to claim 2, characterized in that, The N-level oil tank (200) has a stepped structure, so that along the first direction, the N-level oil tank corresponds at least partially to the side of the oil overflowing from the N-1-level oil tank.

4. The diffusion pump according to claim 3, characterized in that, The oil in the (N-1)th stage oil tank overflows on the side closest to the reference axis; Along the first direction, the radial dimension of the contour of the Nth level oil groove on the side near the reference axis is smaller than the radial dimension of the contour of the (N-1)th level oil groove on the side near the reference axis. The reference axis is the axis of the shell assembly (100).

5. The diffusion pump according to claim 3, characterized in that, The N-level oil groove (200) is disposed on the shell assembly (100). Along the first direction, the radial dimension of the inner wall of the shell assembly (100) gradually decreases, so that the radial dimension of the N-level oil groove on the side away from the reference axis is smaller than the radial dimension of the (N-1)-level oil groove on the side away from the reference axis, and the radial dimension of the N-level oil groove on the side away from the reference axis is larger than the radial dimension of the (N-1)-level oil groove on the side close to the reference axis.

6. The diffusion pump according to any one of claims 1-5, characterized in that, The Nth level oil tank includes: The bottom wall (210) is connected to the shell assembly (100) and is provided continuously or intermittently along the circumference of the shell assembly (100); The sidewall (220) is connected to the bottom wall (210), and the sidewall (220), the bottom wall (210) and the shell assembly (100) are arranged to form an oil tank for containing oil.

7. The diffusion pump according to any one of claims 1-5, characterized in that, The heating component (300) is a magnetic induction heating element.

8. The diffusion pump according to claim 7, characterized in that, The heating assembly (300) includes: A coil (310) is fitted onto the housing assembly (100), the coil (310) being configured to generate a magnetic field when energized; An induction heating element (320) is disposed in each stage of the N-stage oil tank (200), and the induction heating element (320) is configured to generate heat under the action of the magnetic field to heat the oil.

9. The diffusion pump according to claim 8, characterized in that, The heating assembly (300) also includes: Insulating cotton (330) is disposed between the coil (310) and the shell assembly (100), and the insulating cotton (330) is configured to insulate the evaporation chamber (120).

10. The diffusion pump according to any one of claims 1-5, characterized in that, The diffusion pump also includes: An oil circulation mechanism (400) is provided, one end of which is connected to the side of the evaporation chamber (120) away from the diffusion chamber (110) and is used to discharge the oil at the bottom of the evaporation chamber (120). The other end of the oil circulation mechanism (400) is connected to the side of the evaporation chamber (120) near the diffusion chamber (110), and / or the other end of the oil circulation mechanism (400) is connected to the evaporation chamber (120). The oil circulation mechanism (400) is configured to supply oil to the diffusion chamber (110) and / or the evaporation chamber (120) so that the oil flows to the N-stage oil tank (200).

11. The diffusion pump according to claim 10, characterized in that, The oil circulation mechanism (400) includes: First oil storage tank (410); The first connecting pipe (420) is connected at one end to the side of the evaporation chamber (120) away from the diffusion chamber (110), and at the other end to the first oil storage tank (410). The first connecting pipe (420) protrudes from the shell assembly (100) at a preset height in the evaporation chamber (120) so that when the liquid level of the oil in the evaporation chamber (120) is higher than the preset height, the oil above the preset height flows into the first oil storage tank (410).

12. The diffusion pump according to claim 11, characterized in that, The oil circulation mechanism (400) further includes: A first oil supply assembly (430) is configured to supply oil from the first oil storage tank (410) to the evaporation chamber (120) and / or the diffusion chamber (110) when the oil level in the N-stage oil tank (200) decreases, so that at least a portion of the oil is supplied to the N-stage oil tank (200). And / or, the first oil supply assembly (430) is configured to supply oil from the first oil reservoir (410) to the evaporation chamber (120) and / or the diffusion chamber (110) when cooling oil is required, so that at least a portion of the oil is supplied to the N-stage oil tank (200).

13. The diffusion pump according to claim 12, characterized in that, The first oil supply assembly (430) includes: Pump body (431), the pump body (431) being configured to draw oil from the first oil storage tank (410); The second connecting pipe (432) is connected at one end to the discharge end of the pump body (431) and at the other end to the evaporation chamber (120) and / or the diffusion chamber (110). The second connecting pipe (432) is provided with a first oil outlet (433), which faces the inner wall of the shell assembly (100) to discharge oil.

14. The diffusion pump according to claim 13, characterized in that, The diffusion pump further includes a nozzle (500), the second connecting pipe (432) further includes a second oil outlet (434), the second oil outlet (434) is configured to discharge oil to the nozzle (500), and the first oil supply assembly (430) further includes: A first valve body (435) is configured to allow the second connecting pipe (432) to discharge oil through the first oil outlet (433), or the first valve body (435) is configured to allow the second connecting pipe (432) to discharge oil through the second oil outlet (434).

15. The diffusion pump according to claim 10, characterized in that, The oil circulation mechanism (400) further includes a second oil supply assembly (440), which includes: The second oil tank (441) has its outlet end selectively connected to the diffusion cavity (110). When the outlet end of the second oil tank (441) is connected to the diffusion cavity (110), the second oil tank (441) is configured to discharge oil to the inner wall of the shell assembly (100) so that the oil flows to the N-stage oil tank (200). The second valve body (442) is located at the liquid outlet end of the second oil storage tank (441). The second valve body (442) is configured to control the liquid outlet end of the second oil storage tank (441) to connect or disconnect from the evaporation chamber (120). The third valve body (443) is located at the inlet end of the second oil tank (441), and the third valve body (443) is configured to control the opening or closing of the inlet end of the second oil tank (441). When the second oil supply assembly (440) is working, the third valve body (443) opens to supply oil to the second oil tank (441). After the second oil tank (441) is full of oil, the third valve body (443) closes and the second valve body (442) opens to replenish the oil in the second oil tank (441) to the N-stage oil tank (200).

16. The diffusion pump according to claim 11, characterized in that, The oil circulation mechanism (400) further includes an oil discharge assembly (450), which includes: The third oil storage tank (451) has its inlet end selectively connected to the first oil storage tank (410); The fourth valve body (452) is located at the inlet end of the third oil tank (451), and the fourth valve body (452) is configured to control the connection or disconnection between the inlet end of the third oil tank (451) and the first oil tank (410). The fifth valve body (453) is located at the liquid outlet end of the third oil tank (451) for opening or closing; When the oil drain assembly (450) is working, the fourth valve body (452) opens to drain the oil in the first oil tank (410) into the third oil tank (451); after the oil in the first oil tank (410) has been drained to a preset capacity, the fourth valve body (452) closes and the fifth valve body (453) opens to drain the oil in the third oil tank (451).

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