Phase transition heat regeneration cryopump

Abstract

The application relates to a phase-change heating regeneration cryogenic pump, which comprises a cryogenic pump body, a heat pipe, a heater and a heat insulation sleeve; the heat pipe is in contact with a primary cold head and a secondary cold head in the cryogenic pump body from top to bottom and penetrates through a cylinder shell of the cryogenic pump body; the height of the heat pipe is continuously reduced from top to bottom; the heater is located outside the cryogenic pump body and is in contact with the heat pipe; and the heat insulation sleeve is sleeved outside the heat pipe and the heater. The ice crystals in the heat pipe move in the heat pipe through gravity, so that the working fluid in the heat pipe can still be phase-change heat conduction after solidification, the heat conduction efficiency of the heat pipe is greatly improved; heat conduction is carried out through the heat pipe, so that the heater is located outside the cryogenic pump body, a heater with larger area and power can be arranged, the heat quantity supplied to the cold head per unit time is increased, the regeneration time is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of cryogenic pumps, and in particular to a cryogenic pump with phase change heating regeneration. Background Technology

[0002] The operating temperature of existing heat pipes cannot be lower than the freezing point of the working fluid inside them; otherwise, the working fluid will solidify and will not be able to reach the heat absorption section through capillary action. This will cause the working fluid inside the heat pipe to stop phase change, resulting in a significant decrease in the heat pipe's thermal conductivity.

[0003] Cryogenic pumps are storage-type vacuum pumps. They contain an extremely low-temperature surface that captures gases through condensation and adsorption to achieve ultra-high vacuum. Cryogenic pumps can obtain clean vacuums with the highest pumping rates and lowest ultimate pressures, and are widely used in semiconductor and integrated circuit research and production, as well as in molecular beam research, vacuum coating equipment, vacuum surface analysis instruments, ion implanters, and space simulation devices.

[0004] When a cryogenic pump reaches its saturation capacity after long-term operation, its pumping speed drops sharply. At this point, it is necessary to stop the pump and raise the temperature to release the gas adsorbed on the cryogenic plate and restore its original pumping performance. The process of raising the temperature and using a pre-pump to remove the released condensed and adsorbed gas is called "regeneration".

[0005] Regeneration can be achieved in the following ways:

[0006] ① Natural heating method: Turn off the power to the refrigeration unit and use the heat from the pump wall to slowly heat up the cryogenic pump. The heating is very slow at first, but when the pressure inside the pump rises to the point where convection heat transfer takes effect, the heating rate accelerates and eventually reaches a stable temperature.

[0007] ② Venting and Heating Method: After shutting down the refrigeration unit, open the vent valve to release clean, dry air, causing the low-temperature pump's low-temperature plate to heat up rapidly.

[0008] ③ Electric heating method: Electric heaters are installed on the primary and secondary cold heads of the cryogenic pump. During regeneration, the low-temperature plate is heated by electricity to quickly raise the temperature and shorten the regeneration time.

[0009] The existing electric heating method uses an electric heating rod with a metal shell inserted into the cryogenic pump. Inside the empty metal shell are multiple heating wires and silicone. The silicone is located between the heating wires and the metal shell to prevent the heating wires from contacting each other or the heating rod shell, thus preventing short circuits.

[0010] Thinner silicone rubber has better thermal conductivity, but it also makes the heating element more prone to short circuits, leading to electromagnetic interference. Conversely, thicker silicone rubber reduces the likelihood of short circuits, but reduces thermal conductivity. Because of the poor thermal conductivity of silicone rubber, and the relatively thick silicone rubber layer in existing heating elements, the heating output of the heating element to the cold head cannot be further increased, resulting in longer regeneration times. Furthermore, the need for limited internal space in cryogenic pumps and a reduction in the number of sealing interfaces prevents increasing the number of heating elements from increasing the heating output. Summary of the Invention

[0011] This invention provides a cryogenic pump for phase change heating and regeneration, which solves the above-mentioned technical problems.

[0012] A cryogenic pump with phase change heating regeneration includes a cryogenic pump body, a heat pipe, a heater, and a heat insulation sleeve. The heat pipe contacts a primary cold head and a secondary cold head inside the cryogenic pump body from top to bottom and passes through the cylinder housing of the cryogenic pump body. The height of the heat pipe decreases continuously from top to bottom. The heater is located outside the cryogenic pump body and contacts the heat pipe. The heat insulation sleeve is fitted on the outside of the heat pipe and the heater.

[0013] Furthermore, the heat pipe includes a tube body, the tube body is closed at both ends, the tube body is filled with working fluid, and the tube body passes through the cylinder housing and is fixedly connected to the cylinder housing.

[0014] Furthermore, the heat pipe includes a non-stick coating, which is located inside the pipe body and adheres to the inner wall of the pipe body, and is fixedly connected to the pipe body.

[0015] Furthermore, the tube body is made of aluminum, copper, aluminum alloy, or copper alloy, and the non-stick coating is a polytetrafluoroethylene coating.

[0016] Furthermore, the working fluid inside the tube has a melting point below -100°C and a critical temperature above 0°C.

[0017] Furthermore, the working fluid is ethanol, R23, R508B, or R600a.

[0018] Furthermore, the portion of the heat pipe extending out of the cryogenic pump body has a flat plate portion, and the heater contacts and is fixedly connected to the flat plate portion. The heater is an electric heater.

[0019] Furthermore, the heat insulation sleeve is a rigid outer shell, the heat insulation sleeve is fixedly connected to the cylinder housing, the heat insulation sleeve does not contact the heat pipe and heater, and a vacuum environment is formed inside the heat insulation sleeve.

[0020] Furthermore, a reflective layer is fixedly provided on the inner wall of the heat insulation sleeve.

[0021] Furthermore, it also includes a first fixing device and a second fixing device, wherein the first fixing device fixes the heat pipe to the primary cold head, and the second fixing device fixes the heat pipe to the secondary cold head.

[0022] The present invention has the following advantages:

[0023] 1. Ice crystals inside the heat pipe move within the heat pipe due to gravity, allowing the working fluid inside the heat pipe to still undergo phase change heat conduction after solidification, greatly improving the heat conduction efficiency of the heat pipe.

[0024] 2. By conducting heat through heat pipes, the heater is located outside the cryogenic pump body, which allows for the installation of a heater with a larger area and power, increasing the heat delivered to the cold head per unit time, reducing regeneration time, and improving production efficiency;

[0025] 3. The heater is located outside the cryogenic pump body, and there is sufficient space between the heater and the heat pipe for insulation, which avoids the short circuit of the heating rod in the existing technology from affecting the normal operation of the cryogenic pump and improves the reliability of the cryogenic pump.

[0026] 4. The heat pipe and heater are insulated by a heat insulation jacket, which reduces the heat exchange between the heat pipe and the outside environment when the heat pipe is adsorbed at low temperature by the cryogenic pump and heated by the cryogenic pump.

[0027] 5. A thick insulation layer can be used between the heat pipe and the heater, or the heater can be equipped with an insulating shell. The heat pipe is not energized, thus avoiding electromagnetic interference to the pump's internal and external equipment caused by short circuits in existing technologies. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other embodiments can be derived from the provided drawings without creative effort.

[0029] Figure 1 : A three-dimensional structural diagram of the cryogenic pump body;

[0030] Figure 2 : A three-dimensional structural diagram of the present invention with some components removed;

[0031] Figure 3 : A cross-sectional view of the present invention with some components removed;

[0032] Figure 4 : Figure 3 Schematic diagram of the cross-sectional structure at point AA;

[0033] Figure 5 : Figure 3A magnified view of a section at point B. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and examples:

[0035] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0038] like Figures 1 to 5 As shown, a cryogenic pump with phase change heating regeneration includes a cryogenic pump body 1, a heat pipe 2, a heater 3, and a heat insulation sleeve 8. The heat pipe 2 contacts the first-stage cold head 14 and the second-stage cold head 15 inside the cryogenic pump body 1 from top to bottom and passes through the cylinder housing 10 of the cryogenic pump body 1. The height of the heat pipe 2 decreases continuously from top to bottom. The heater 3 is located outside the cryogenic pump body 1 and contacts the heat pipe 2. The heat insulation sleeve 8 is fitted on the outside of the heat pipe 2 and the heater 3.

[0039] Preferably, the inner wall of the heat pipe 2 is smooth and has no capillary structure, so as to minimize the friction between the solidified working fluid (ice crystals) and the heat pipe 2.

[0040] Optionally, a single heat pipe 2 can be used to contact both the primary cold head 14 and the secondary cold head 15 simultaneously, such as... Figure 2 and Figure 3 As shown.

[0041] Optionally, multiple heat pipes 2 are used, with each heat pipe 2 contacting only one of the primary cold head 14 and the secondary cold head 15, as shown in the figure.

[0042] Furthermore, the heat pipe 2 includes a pipe body 20, which is closed at both ends and filled with a working fluid. The pipe body 20 passes through the cylinder housing 10 and is fixedly connected to the cylinder housing 10. A seal is used between the heat pipe 2 and the cylinder housing 10.

[0043] Preferably, the heat pipe 2 is welded and fixed to the cylinder housing 10.

[0044] Furthermore, the heat pipe 2 includes a non-stick coating 22, which is located inside the pipe body 20 and adheres to the inner wall of the pipe body 20. The non-stick coating 22 is fixedly connected to the pipe body 20. The non-stick coating 22 is used to reduce the friction between ice crystals formed by the solidification of the working fluid and the inner wall of the heat pipe 2, preventing ice crystals from getting stuck in the middle of the heat pipe 2 and continuing to slide downwards.

[0045] Preferably, the non-stick coating 22 is fixed to the inner wall of the tube body 20 by existing processes such as electroplating, vapor deposition, sintering, and coating.

[0046] Furthermore, the tube body 20 is made of aluminum, copper, aluminum alloy, or copper alloy, and the non-stick coating 22 is a polytetrafluoroethylene coating.

[0047] Furthermore, the working fluid inside the tube 20 has a melting point below -100°C and a critical temperature above 0°C.

[0048] Furthermore, the working fluid is ethanol, R23, R508B, or R600a.

[0049] Furthermore, the portion of the heat pipe 2 extending out of the cryogenic pump body 1 forms a flat plate portion 21, and the heater 3 is in contact with and fixedly connected to the flat plate portion 21. The heater 3 is an electric heater. The flat plate portion 21 increases the surface area, thereby increasing the contact area with the heater 3. The flat plate portion 21 has a greater heat conduction per unit time, allowing the heater 3 to use a greater heating power.

[0050] Optionally, the heat pipe 2 is brazed to the primary cold head 14, and the heat pipe 2 is brazed to the secondary cold head 15.

[0051] Optionally, it also includes a first fixing device 4 and a second fixing device 5, wherein the first fixing device 4 fixes the heat pipe 2 to the primary cold head 14, and the second fixing device 5 fixes the heat pipe 2 to the secondary cold head 15.

[0052] Preferably, the first fixing device 4 and the second fixing device 5 can be fixing blocks (such as...). Figure 2 and Figure 3 (As shown) or clamps. The fixing block is fixed to the cold head by screws; the clamps tighten the cold head and heat pipe 2 inside, making them contact each other.

[0053] Preferably, the tiny gaps on the surface between the heat pipe 2 and the first fixing device 4 and the second fixing device 5 are filled with thermally conductive materials such as silicone grease.

[0054] Furthermore, the heat insulation sleeve 8 is a rigid outer shell, the heat insulation sleeve 8 is fixedly connected to the cylinder housing 10, the heat insulation sleeve 8 does not contact the heat pipe 2 and the heater 3, and a vacuum environment is formed inside the heat insulation sleeve 8.

[0055] Preferably, the heat insulation sleeve 8 is made of metal and is welded and fixed to the cylinder housing 10.

[0056] Furthermore, a reflective layer 85 is fixedly provided on the inner wall of the heat insulation sleeve 8.

[0057] Preferably, the reflective layer 85 is a silver plating layer.

[0058] Furthermore, the angle between the heat pipe 2 and the horizontal plane is greater than 45 degrees, which makes it easier for ice crystals to fall.

[0059] During operation: The outer casing 11 needs to be positioned above the cylinder housing 10. The internal temperature of the cryogenic pump body 1 is lowered, allowing the cold shield 12 and cold umbrella 13 to adsorb molecules in the gas at low temperatures. During operation, due to the extremely low temperature of the cryogenic pump body 1, the working fluid inside the heat pipe 2 will solidify into ice crystals. Under the influence of gravity, the ice crystals will slide down the heat pipe 2 until they reach the outside of the cylinder housing 10 (or enter the plate section 21 if one is present). Because the vacuum environment inside the heat insulation sleeve 8 blocks heat exchange between the heat pipe 2 and the outside, the influence of the external temperature of the cryogenic pump body 1 on its interior is reduced, allowing the cold shield 2 and cold umbrella 3 inside the cryogenic pump body 1 to successfully lower to the specified temperature.

[0060] During regeneration: Heater 3 heats the plate section 21, melting the ice crystals, which then vaporize or sublimate. The vaporized working fluid moves to the contact point between heat pipe 2 and the primary and secondary cold heads 14 and 15, where it liquefies or condenses. The released working fluid or its transformed ice crystals, under the influence of gravity, move downwards along heat pipe 2 to the plate section 21 to continue absorbing heat, completing the phase change cycle of the heat pipe.

[0061] After the working fluid solidifies, heat pipe 2 smoothly undergoes a phase change for heat conduction, greatly improving the heat conduction efficiency. This allows a large amount of heat to be transferred to the primary cold head 14 and the secondary cold head 15 in a short time, causing them to heat up rapidly and shortening the regeneration time. Subsequently, based on the temperature sensor inside the cryogenic pump body 1, the heater 3 stops working once the specified temperature is reached.

[0062] It should be noted that the cryogenic pump body 1 is a cryogenic pump of the prior art, such as the cryogenic pump disclosed in Chinese invention patent with authorization announcement number CN117489563B. The primary cold head 14 and the secondary cold head 15 of the cryogenic pump body 1 are located inside the cylinder housing 10 and the outer housing 11, respectively, and the cylinder housing 10 and the outer housing 11 are fixedly connected. The cold shield 2 and the cold umbrella 3 of the cryogenic pump body 1 are disposed inside the outer housing 11, and the end of the cylinder housing 10 is fixed to the base through the cold head base 16.

[0063] It should be noted that controllable heat pipe heating devices can be used not only in cryogenic pumps, but also in cryogenic fields such as experiments or aerospace.

[0064] The present invention has been described above by way of example, but the present invention is not limited to the specific embodiments described above. Any modifications or variations made based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A cryogenic pump for phase change heating regeneration, comprising a cryogenic pump body (1), characterized in that: It also includes a heat pipe (2), a heater (3) and a heat insulation sleeve (8). The heat pipe (2) contacts the first-stage cold head (14) and the second-stage cold head (15) inside the cryogenic pump body (1) from top to bottom and passes through the cylinder housing (10) of the cryogenic pump body (1). The height of the heat pipe (2) decreases continuously from top to bottom. The heater (3) is located outside the cryogenic pump body (1) and contacts the heat pipe (2). The heat insulation sleeve (8) is fitted on the outside of the heat pipe (2) and the heater (3). The heat pipe (2) includes a pipe body (20), which is closed at both ends. The pipe body (20) is filled with working fluid. The pipe body (20) passes through the cylinder housing (10) and is fixedly connected to the cylinder housing (10). The heat pipe (2) includes a non-stick coating (22), which is located inside the pipe body (20) and adheres to the inner wall of the pipe body (20). The non-stick coating (22) is fixedly connected to the pipe body (20). During operation, due to the low temperature of the cryogenic pump body (1), the working fluid in the heat pipe (2) will solidify into ice crystals.

2. The cryogenic pump for phase change heating regeneration according to claim 1, characterized in that: The tube body (20) is made of aluminum, copper, aluminum alloy or copper alloy, and the non-stick coating (22) is a polytetrafluoroethylene coating.

3. The cryogenic pump for phase change heating regeneration according to claim 1, characterized in that: The working fluid inside the tube (20) has a melting point below -100°C and a critical temperature above 0°C.

4. A cryogenic pump for phase change heating regeneration according to claim 3, characterized in that: The working fluid is ethanol, R23, R508B, or R600a.

5. A cryogenic pump for phase change heating regeneration according to claim 1, characterized in that: The portion of the heat pipe (2) extending out of the cryogenic pump body (1) forms a flat plate (21), and the heater (3) contacts and is fixedly connected to the flat plate (21). The heater (3) is an electric heater.

6. A cryogenic pump for phase change heating regeneration according to claim 1, characterized in that: The heat insulation sleeve (8) is a rigid outer shell. The heat insulation sleeve (8) is fixedly connected to the cylinder housing (10). The heat insulation sleeve (8) does not contact the heat pipe (2) and the heater (3). A vacuum environment is formed inside the heat insulation sleeve (8).

7. A cryogenic pump for phase change heating regeneration according to claim 1, characterized in that: The angle between the heat pipe (2) and the horizontal plane is greater than 45 degrees.

8. A cryogenic pump for phase change heating regeneration according to claim 1, characterized in that: It also includes a first fixing device (4) and a second fixing device (5), the first fixing device (4) fixing the heat pipe (2) to the first-stage cold head (14) and the second fixing device (5) fixing the heat pipe (2) to the second-stage cold head (15).

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