Phase change heating regeneration cryopump

Abstract

The invention relates to a phase change heating regeneration cryopump which comprises a cryopump body and further comprises a heat pipe, a heater and a heat insulation sleeve, the heat pipe is sequentially in contact with a primary cold head and a secondary cold head in the cryopump body from top to bottom and penetrates through an air cylinder shell of the cryopump body, and the height of the heat pipe is continuously decreased from top to bottom; the heater is located outside the low-temperature pump body and makes contact with the heat pipe, and the heat insulation sleeve is arranged on the outer side of the heat pipe and the heater in a sleeving mode. Ice crystals in the heat pipe move in the heat pipe through gravity, so that working fluid in the heat pipe can still conduct phase change heat conduction after being solidified, and the heat conduction efficiency of the heat pipe is greatly improved; heat is conducted through the heat pipe, the heater is located on the outer side of the low-temperature pump body, and therefore the heater with larger area and power can be arranged, heat supplied to a cold head in unit time is increased, regeneration time is shortened, and production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of cryogenic pumps, in particular to a phase-change heating regeneration cryogenic pump. Background Art

[0002] The operating temperature of the existing heat pipe cannot be lower than the freezing point of the working fluid inside it, otherwise the working fluid will solidify and cannot reach the heat absorption section through capillary action, thereby stopping the phase change of the working fluid in the heat pipe and greatly reducing the thermal conductivity of the heat pipe.

[0003] Cryopumps are storage vacuum pumps with extremely low temperature surfaces inside the pumps, which can capture gases through condensation and adsorption to achieve ultra-high vacuum. Cryopumps can obtain clean vacuum with the highest pumping rate and the lowest ultimate pressure, and are widely used in the research and production of semiconductors and integrated circuits, as well as molecular beam research, vacuum coating equipment, vacuum surface analysis instruments, ion implanters, and space simulation devices.

[0004] When the cryopump reaches saturation capacity after long-term operation, the pumping speed drops sharply. At this time, it is necessary to stop the pump and raise the temperature to release the gas adsorbed on the cryopanel and restore the original pumping performance. Heating the temperature and using the pre-pump to pump out the released condensed and adsorbed gas is called "regeneration".

[0005] There are several ways to regenerate: ① Natural heating method: Turn off the power of the refrigerator and use the heat of the pump wall to slowly heat up the cryopump. The temperature rises very slowly at the beginning. When the pressure in the pump rises to the point where convection heat transfer takes effect, the heating rate accelerates and finally reaches a stable temperature rise value.

[0006] ② Venting and heating method: After stopping the refrigerator, open the vent valve to let in clean and dry air to quickly heat up the cryopump cryopanel ③ Electric heating method: Electric heaters are installed on the first and second stage cold heads in the cryopump. During regeneration, electric heating is applied to quickly heat up the cryopanel to shorten the regeneration time.

[0007] The existing electric heating method uses an electric heating rod with a metal shell to penetrate into the cryopump. 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, thereby preventing a short circuit.

[0008] The thinner the thickness of the silicone, the better the thermal conductivity, but the electric heating rod is more likely to short-circuit, thus causing electromagnetic interference; the thicker the silicone, the less likely it is to short-circuit, but the worse the thermal conductivity. Because the thermal conductivity of silicone is poor, and the thickness of the silicone in the existing electric heating rod is large, the heating capacity of the electric heating rod to the cold head cannot be further increased, and the time required for electric heating regeneration is longer. In addition, due to the priority of the internal space of the cryopump and the need to reduce the number of sealing interfaces, the heating capacity cannot be increased by increasing the number of heating rods. Summary of the invention

[0009] The present invention provides a phase-change heating regeneration cryogenic pump, which solves the above technical problems.

[0010] A phase-change heating regeneration cryopump comprises a cryopump body, a heat pipe, a heater and a thermal insulation sleeve. The heat pipe sequentially contacts a primary cold head and a secondary cold head inside the cryopump body from top to bottom and passes through a cylinder shell of the cryopump body. The heat pipe decreases in height from top to bottom. The heater is located outside the cryopump body and contacts the heat pipe. The thermal insulation sleeve is sleeved on the outside of the heat pipe and the heater.

[0011] Furthermore, the heat pipe comprises a tube body, both ends of which are closed, the tube body is filled with a working fluid, and the tube body passes through the cylinder shell and is fixedly connected to the cylinder shell.

[0012] Furthermore, the heat pipe includes a non-stick coating, which is located inside the pipe body and fits the inner wall of the pipe body, and is fixedly connected to the pipe body.

[0013] Furthermore, the tube body is made of aluminum, copper, aluminum alloy or copper alloy, and the non-stick coating is a polytetrafluoroethylene coating.

[0014] Furthermore, the melting point of the working fluid in the tube body is lower than -100°C and the critical temperature is higher than 0°C.

[0015] Furthermore, the working fluid is ethanol, R23, ‌R508B or R600a.

[0016] Furthermore, a portion of the heat pipe extending out of the cryopump body is formed with a flat plate portion, the heater is in contact with and fixedly connected to the flat plate portion, and the heater is an electric heater.

[0017] Furthermore, the thermal insulation sleeve is a hard outer shell, the thermal insulation sleeve is fixedly connected to the cylinder shell, the thermal insulation sleeve is not in contact with the heat pipe and the heater, and a vacuum environment is formed inside the thermal insulation sleeve.

[0018] Furthermore, a reflective layer is fixedly provided on the inner wall of the thermal insulation sleeve.

[0019] Furthermore, it also includes a first fixing device and a second fixing device, wherein the first fixing device fixes the heat pipe to the first-level cold head, and the second fixing device fixes the heat pipe to the second-level cold head.

[0020] The present invention has the following advantages: 1. The ice crystals in the heat pipe move in the heat pipe by gravity, so that the working fluid in the heat pipe can still conduct heat by phase change after solidification, which greatly improves the heat conduction efficiency of the heat pipe; 2. Heat conduction is carried out through heat pipes, so that the heater is located outside the cryopump body, so that a heater with a larger area and power can be set, which increases the heat supplied to the cold head per unit time, reduces the regeneration time, and improves production efficiency; 3. The heater is outside the cryopump body, and there is enough space between the heater and the heat pipe for insulation treatment, which avoids the short circuit of the heating rod in the prior art affecting the normal operation of the cryopump and improves the reliability of the cryopump; 4. Use thermal insulation sleeves to insulate the heat pipe and heater, reducing the heat exchange between the heat pipe and the outside world when the cryopump is adsorbing low temperature and the cryopump is heating up; 5. A thicker insulating layer can be used between the heat pipe and the heater, or the heater can be provided with an insulating casing. The heat pipe is not energized, thus avoiding electromagnetic interference to the equipment inside and outside the pump caused by the short circuit in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0022] Figure 1 : Schematic diagram of the three-dimensional structure of the cryopump body; Figure 2 : A schematic diagram of the three-dimensional structure of the present invention with some components removed; Figure 3 : A schematic cross-sectional view of the present invention with some components removed; Figure 4 : Figure 3 Schematic diagram of the cross-sectional structure at AA in the middle; Figure 5 : Figure 3 A partial enlarged view of point B in the middle. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and examples: Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention. like Figures 1 to 5 As shown, a phase change heating regeneration cryopump includes a cryopump body 1, a heat pipe 2, a heater 3 and an insulation sleeve 8. The heat pipe 2 contacts the primary cold head 14 and the secondary cold head 15 inside the cryopump body 1 from top to bottom and passes through the cylinder shell 10 of the cryopump body 1. The heat pipe 2 decreases in height from top to bottom. The heater 3 is located outside the cryopump body 1 and contacts the heat pipe 2. The insulation sleeve 8 is mounted on the outside of the heat pipe 2 and the heater 3.

[0026] Preferably, the inner wall of the heat pipe 2 is smooth and has no capillary structure, so as to reduce the friction between the solidified working fluid (ice crystals) and the heat pipe 2 as much as possible.

[0027] Optionally, a heat pipe 2 is used to contact the primary cold head 14 and the secondary cold head 15 at the same time, such as Figure 2 and Figure 3 shown.

[0028] Optionally, a plurality of heat pipes 2 are used, and one heat pipe 2 is in contact with only one of the primary cold head 14 and the secondary cold head 15 , which is not shown in the figure.

[0029] Furthermore, the heat pipe 2 includes a tube body 20, the two ends of the tube body 20 are closed, the tube body 20 is filled with a working fluid, and the tube body 20 passes through the cylinder housing 10 and is fixedly connected to the cylinder housing 10. The heat pipe 2 and the cylinder housing 10 are sealed.

[0030] Preferably, the heat pipe 2 is fixed to the cylinder housing 10 by welding.

[0031] Furthermore, the heat pipe 2 includes a non-stick coating 22, which is located inside the tube body 20 and fits against the inner wall of the tube body 20, and is fixedly connected to the tube body 20. The non-stick coating 22 is used to reduce the friction between ice crystals formed by solidification of the working fluid and the inner wall of the heat pipe 2, so as to prevent the ice crystals from getting stuck in the middle of the heat pipe 2 and not continuing to slide downward.

[0032] Preferably, the non-stick coating 22 is fixed on the inner wall of the tube body 20 by existing processes such as electroplating, evaporation, sintering, and coating.

[0033] 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.

[0034] Furthermore, the melting point of the working fluid in the tube body 20 is lower than -100°C and the critical temperature is higher than 0°C.

[0035] Furthermore, the working fluid is ethanol, R23, ‌R508B or R600a.

[0036] Furthermore, the portion of the heat pipe 2 extending out of the cryopump body 1 is formed with a flat plate portion 21, and the heater 3 is in contact with and fixedly connected to the flat plate portion 21, and 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, so that the heater 3 matched therewith can adopt a greater heating power.

[0037] Optionally, the heat pipe 2 is fixed to the primary cold head 14 by brazing, and the heat pipe 2 is fixed to the secondary cold head 15 by brazing.

[0038] Optionally, it further 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 .

[0039] Preferably, the first fixing device 4 and the second fixing device 5 can be fixed blocks (such as Figure 2 and Figure 3 The fixing block is fixedly connected to the cold head by screws; the clamp clamps the cold head and the heat pipe 2 inside it tightly so that they are in contact with each other.

[0040] Preferably, thermally conductive materials such as silicone grease are used to fill tiny gaps on the surface between the heat pipe 2 and the first fixing device 4 and the second fixing device 5 .

[0041] Furthermore, the thermal insulation sleeve 8 is a hard shell, the thermal insulation sleeve 8 is fixedly connected to the cylinder housing 10, the thermal insulation sleeve 8 is not in contact with the heat pipe 2 and the heater 3, and a vacuum environment is formed inside the thermal insulation sleeve 8.

[0042] Preferably, the heat insulation sleeve 8 is made of metal material, and the heat insulation sleeve 8 is fixed to the cylinder housing 10 by welding.

[0043] Furthermore, a reflective layer 85 is fixedly disposed on the inner wall of the heat insulation sleeve 8 .

[0044] Preferably, the reflective layer 85 is a silver-plated layer.

[0045] Furthermore, the angle between the heat pipe 2 and the horizontal plane is greater than 45 degrees, so that ice crystals can fall more easily.

[0046] During operation: the outer shell 11 needs to be located above the cylinder shell 10, and the temperature inside the cryopump body 1 is lowered so that the cold screen 12 and the cold umbrella 13 adsorb the molecules in the gas at a low temperature. During operation, since the temperature of the cryopump body 1 is too low, the working fluid in the heat pipe 2 will solidify into ice crystals. Under the action of gravity, the ice crystals will slide downward along the heat pipe 2 until they reach the outside of the cylinder shell 10 (if there is a flat plate 21, they will enter the flat plate 21). Since the vacuum environment inside the insulation sleeve 8 blocks the heat exchange between the heat pipe 2 and the outside world, the influence of the temperature outside the cryopump body 1 on its interior is reduced, so that the cold screen 2 and the cold umbrella 3 inside the cryopump body 1 can be smoothly lowered to the specified temperature.

[0047] During regeneration: the heater 3 heats the flat plate 21, and the heat melts the ice crystals and then vaporizes or sublimates them. The vaporized working fluid moves to the contact point between the heat pipe 2 and the primary cold head 14 and the secondary cold head 15, and liquefies or condenses at the contact point between the heat pipe 2 and the primary cold head 14 and the secondary cold head 15. The working fluid or its transformed ice crystals move downward along the heat pipe 2 to the flat plate 21 under the force of gravity to continue absorbing heat, completing the phase change cycle of the heat pipe.

[0048] After the working fluid solidifies, the heat pipe 2 smoothly changes phase to conduct heat, and the heat conduction efficiency is greatly improved, so that a large amount of heat can be transferred to the primary cold head 14 and the secondary cold head 15 in a short time, so that the primary cold head 14 and the secondary cold head 15 are quickly heated up, shortening the regeneration time. Afterwards, according to the temperature sensor inside the cryopump body 1, when the specified temperature is reached, the heater 3 stops working.

[0049] It should be noted that the cryopump body 1 is a cryopump of the prior art, such as the cryopump disclosed in the Chinese invention patent with the authorization announcement number CN117489563B. The first-stage cold head 14 and the second-stage cold head 15 of the cryopump body 1 are respectively located inside the cylinder housing 10 and the outer housing 11, and the cylinder housing 10 and the outer housing 11 are fixedly connected. The cold shield 2 and the cold umbrella 3 of the cryopump body 1 are arranged inside the outer housing 11, and the end of the cylinder housing 10 is fixed to the base through the cold head base 16.

[0050] It should be noted that the controllable heat pipe heating device can be used not only in cryogenic pumps, but also in low-temperature fields such as experiments or aerospace.

[0051] The present invention is described above by way of examples, but the present invention is not limited to the above specific embodiments, and any changes or modifications made based on the present invention belong to the scope of protection claimed by the present invention.

Claims

1. A phase change heating regeneration cryopump, comprising a cryopump body (1), characterized in that: The invention also comprises 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 cryopump body (1) from top to bottom in sequence and passes through the cylinder shell (10) of the cryopump body (1); the heat pipe (2) decreases in height from top to bottom; the heater (3) is located outside the cryopump body (1) and contacts the heat pipe (2); and the heat insulation sleeve (8) is sleeved on the outside of the heat pipe (2) and the heater (3).

2. A phase change heating regeneration cryopump according to claim 1, characterized in that: The heat pipe (2) comprises a tube body (20), both ends of the tube body (20) are closed, the tube body (20) is filled with a working fluid, and the tube body (20) passes through the cylinder shell (10) and is fixedly connected to the cylinder shell (10).

3. A phase change heating regeneration cryopump according to claim 2, characterized in that: The heat pipe (2) comprises a non-stick coating (22), the non-stick coating (22) is located on the inner side of the pipe body (20) and is in contact with the inner wall of the pipe body (20), and the non-stick coating (22) is fixedly connected to the pipe body (20).

4. A phase change heating regeneration cryopump according to claim 3, 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.

5. A phase change heating regeneration cryopump according to claim 2, characterized in that: The working fluid in the tube body (20) has a melting point lower than -100°C and a critical temperature higher than 0°C.

6. A phase change heating regeneration cryopump according to claim 5, characterized in that: The working fluid is ethanol, R23, ‌R508B or R600a.

7. The phase change heating regeneration cryopump according to claim 1, characterized in that: The portion of the heat pipe (2) extending out of the cryopump body (1) is formed with a flat plate portion (21), the heater (3) is in contact with and fixedly connected to the flat plate portion (21), and the heater (3) is an electric heater.

8. The phase change heating regeneration cryopump according to claim 1, characterized in that: The thermal insulation sleeve (8) is a hard outer shell, the thermal insulation sleeve (8) is fixedly connected to the cylinder shell (10), the thermal insulation sleeve (8) is not in contact with the heat pipe (2) and the heater (3), and a vacuum environment is formed inside the thermal insulation sleeve (8).

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

10. The phase change heating regeneration cryopump according to claim 1, characterized in that: It also comprises a first fixing device (4) and a second fixing device (5), wherein the first fixing device (4) fixes the heat pipe (2) to the first-level cold head (14), and the second fixing device (5) fixes the heat pipe (2) to the second-level cold head (15).

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