Cryopump

Abstract

The present invention addresses the problem of improving the utility of a safe purge function of a cryopump. A cryopump (10) is provided with a purge valve provided with: a main valve (60) that closes to block purge gas by the supply of fluid from a fluid source, and opens to supply purge gas by the discharge of fluid; and a pilot valve (70) that switches between a first state in which fluid is supplied from a fluid source to the main valve (60) and a second state in which fluid is discharged from the main valve (60). The purge valve is configured so as to restrict the discharge of fluid from the main valve (60) when the supply of fluid from the fluid source is interrupted in the first state of the pilot valve (70).

Description

[0001] This application claims priority based on Japanese Patent Application No. 2024-153218, filed on September 5, 2024. The entire contents of that Japanese application are incorporated herein by reference. Technical Field

[0002] This invention relates to a cryogenic pump. Background Technology

[0003] A cryogenic pump is a vacuum pump that traps gas molecules on a cryogenic plate cooled to ultra-low temperatures through condensation or adsorption and then exhausts the gas. Typically, cryogenic pumps are used to achieve the clean vacuum environment required for semiconductor circuit manufacturing processes. In semiconductor manufacturing processes, hazardous gases with various dangers, such as explosiveness, corrosiveness, and toxicity, are sometimes used. If an abnormal event such as a power outage causes an unexpected temperature rise in the cryogenic pump, the hazardous gases stored in the pump may re-vaporize, potentially increasing their concentration within the pump. To address this unsafe condition, a normally open purge valve that automatically returns to an open state during a power outage has been proposed to automatically expel hazardous gases from the cryogenic pump, a process known as a safety purging.

[0004] Patent Document 1: Japanese Patent Publication No. 2007-521438 Summary of the Invention

[0005] One of the exemplary objectives of one embodiment of the present invention is to improve the practicality of the safety purging function of cryogenic pumps.

[0006] According to one embodiment of the present invention, a cryogenic pump includes a purge valve comprising: a main valve, which is closed by fluid supply from a fluid source to block purge gas and opened by fluid discharge to supply purge gas; and a pilot valve, which switches between a first state of supplying fluid from the fluid source to the main valve and a second state of discharging fluid from the main valve. The purge valve is configured such that, in the first state of the pilot valve, when the fluid supply from the fluid source is interrupted, it restricts the discharge of fluid from the main valve.

[0007] According to one embodiment of the present invention, a cryogenic pump includes a purge valve and a backup power supply connected to a pilot valve. The purge valve includes: a main valve, which is closed by fluid supply from a fluid source to block purge gas and opened by fluid discharge to supply purge gas; and a pilot valve, which switches between a first state of supplying fluid from the fluid source to the main valve and a second state of discharging fluid from the main valve. The pilot valve includes a solenoid valve, which recovers from the first state to the second state when the supply voltage drops below a recovery voltage. The backup power supply includes: a storage element; and a boost circuit, which boosts the output voltage of the storage element to exceed the recovery voltage of the solenoid valve to generate a supply voltage supplied to the solenoid valve.

[0008] According to one embodiment of the present invention, a cryogenic pump includes a purge valve and a backup power supply connected to a pilot valve. The purge valve includes: a main valve, which is closed by fluid supply from a fluid source to block purge gas and opened by fluid discharge to supply purge gas; and a pilot valve, which switches between a first state of supplying fluid from the fluid source to the main valve and a second state of discharging fluid from the main valve. The backup power supply includes: a storage element; and a storage element monitor, which monitors the storage element by discharging it.

[0009] Furthermore, any combination of the above-mentioned constituent elements or the constituent elements or manifestations of the present invention that are interchanged among methods, apparatuses, systems, etc., is also effective as a way of presenting the present invention.

[0010] Invention Effects

[0011] According to the present invention, the practicality of the safety purging function of cryogenic pumps can be improved. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing the cryogenic pump system involved in the embodiment.

[0013] Figure 2 This is a schematic diagram showing the cryogenic pump system involved in the embodiment.

[0014] Figure 3 This is a diagram schematically showing an exemplary configuration of the purge valve of the cryogenic pump according to the embodiment.

[0015] Figure 4 This is a diagram schematically showing an exemplary configuration of the purge valve of the cryogenic pump according to the embodiment.

[0016] Figure 5 This is a diagram schematically showing an exemplary configuration of the purge valve of the cryogenic pump according to the embodiment.

[0017] Figure 6 This is a diagram schematically showing an exemplary configuration of the purge valve of the cryogenic pump according to the embodiment.

[0018] Figure 7 This is a schematic diagram showing the power supply system of the purge valve of the cryogenic pump involved in the embodiment.

[0019] In the diagram: 10-Cryogenic pump, 16-Cryogenic pump container, 54-Fluid source, 60-Main valve, 70-Pilot valve, 71-Supply port, 73-Main valve port, 75-Check valve, 82-Backup power supply, 83-Electric storage element, 85-Boost circuit, 92-Electric storage element monitor. Detailed Implementation

[0020] Hereinafter, the embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description and drawings, the same or equivalent constituent elements, components, and processes are labeled with the same symbols, and repeated descriptions are omitted where appropriate. The scales and shapes of the illustrated parts are schematic for ease of explanation and should not be interpreted as limiting unless otherwise stated. The embodiments are illustrative and do not limit the scope of the invention in any way. All features or combinations thereof described in the embodiments are not necessarily essential to the invention.

[0021] Figure 1 and Figure 2 This is a schematic diagram illustrating the cryogenic pump system involved in the embodiment. Figure 1 The appearance of the cryogenic pump 10 is schematically shown in the figure. Figure 2 The internal structure of the cryogenic pump 10 is schematically shown. The cryogenic pump 10 is installed, for example, in the vacuum chamber 100 of an ion implantation apparatus, sputtering apparatus, evaporation apparatus, or other vacuum process apparatus to increase the vacuum level inside the vacuum chamber 100 to the level required by the desired vacuum process. For example, 10 is achieved within the vacuum chamber 100. - 5 Pa to 10 -8 A high vacuum of approximately Pa.

[0022] The cryogenic pump 10 includes a compressor 12, a refrigeration unit 14, and a cryogenic pump container 16. The cryogenic pump container 16 has a cryogenic pump inlet 17. Furthermore, the cryogenic pump 10 includes a roughing valve 18, a main body purge valve 20, a discharge valve 22, and a discharge purge valve 24, which are disposed on the cryogenic pump container 16.

[0023] The compressor 12 is configured to recover refrigerant gas from the refrigerator 14, pressurize the recovered refrigerant gas, and supply the refrigerant gas back to the refrigerator 14. The refrigerator 14, also called an expander or cold head, together with the compressor 12 constitutes a cryogenic refrigerator. The refrigerant gas circulation between the compressor 12 and the refrigerator 14 is achieved through a combination of appropriate pressure and volume variations within the refrigerator 14, thus forming a thermodynamic cycle for refrigeration, enabling the refrigerator 14 to provide cryogenic cooling. The refrigerant gas is typically helium, but other suitable gases can also be used. For ease of understanding, Figure 1 Arrows are used to indicate the direction of refrigerant gas flow. As an example, the cryogenic refrigerator is a two-stage Gifford-McMahon (GM) refrigerator, but it can also be a pulse tube refrigerator, a Stirling refrigerator, or other types of cryogenic refrigerators.

[0024] like Figure 2As shown, the refrigerator 14 includes a room temperature section 26, a first cylinder 28, a first cooling platform 30, a second cylinder 32, and a second cooling platform 34. The refrigerator 14 is configured to cool the first cooling platform 30 to a first cooling temperature and the second cooling platform 34 to a second cooling temperature. The second cooling temperature is lower than the first cooling temperature. For example, the first cooling platform 30 is cooled to about 65K to 120K, preferably 80K to 100K, and the second cooling platform 34 is cooled to about 10K to 20K. The first cooling platform 30 and the second cooling platform 34 may also be referred to as a high-temperature cooling platform and a low-temperature cooling platform, respectively. In this way, by cooling the first cooling platform 30 and the second cooling platform 34 to their respective target cooling temperatures, the cryogenic pump 10 can perform vacuum exhaust operation.

[0025] The first cylinder block 28 connects the first cooling platform 30 to the room temperature section 26, thus the first cooling platform 30 is structurally supported by the room temperature section 26. The second cylinder block 32 connects the second cooling platform 34 to the first cooling platform 30, thus the second cooling platform 34 is structurally supported by the first cooling platform 30. The first cylinder block 28 and the second cylinder block 32 extend coaxially, and the room temperature section 26, the first cylinder block 28, the first cooling platform 30, the second cylinder block 32, and the second cooling platform 34 are arranged in a straight line in sequence.

[0026] In the case where the refrigerator 14 is a two-stage GM refrigerator, a first displacement device and a second displacement device (not shown) are reciprocatingly arranged inside the first cylinder 28 and the second cylinder 32, respectively. A first accumulator and a second accumulator (not shown) are respectively assembled on the first displacement device and the second displacement device. Furthermore, the room temperature section 26 has a drive mechanism 26a, such as a motor, for reciprocating the first displacement device and the second displacement device. The drive mechanism 26a may include a flow path switching mechanism that periodically switches the supply and discharge of working gas (e.g., helium) into the refrigerator 14.

[0027] Furthermore, the cryogenic pump 10 includes a radiation shield 36 and a cryogenic plate 38. The radiation shield 36 is thermally connected to the first cooling stage 30 and cooled to a first cooling temperature to provide an ultra-low temperature surface, which is used to protect the cryogenic plate 38 from radiant heat from the outside of the cryogenic pump 10 or from the cryogenic pump container 16.

[0028] The radiation shield 36 has, for example, a cylindrical shape and is configured to surround the cryogenic plate 38 and the second cooling platform 34. The end of the radiation shield 36 on the cryogenic pump inlet 17 side is open, allowing gas entering from outside the cryogenic pump 10 through the cryogenic pump inlet 17 to be introduced into the radiation shield 36. The end of the radiation shield 36 on the side opposite to the cryogenic pump inlet 17 can be closed, open, or have an opening. A gap exists between the radiation shield 36 and the cryogenic plate 38, and the radiation shield 36 does not contact the cryogenic plate 38. The radiation shield 36 also does not contact the cryogenic pump container 16.

[0029] To protect the cryogenic plate 38 from radiant heat from external heat sources (e.g., heat sources within the vacuum chamber 100 where the cryogenic pump 10 is installed) of the cryogenic pump inlet 17, an inlet baffle 37 may be provided at the cryogenic pump inlet 17 or between the cryogenic pump inlet 17 and the cryogenic plate 38. The inlet baffle 37 may be fixed to the open end of the radiation shield 36 and thermally connected to the first cooling stage 30 of the refrigerator 14 via the radiation shield 36. Alternatively, the inlet baffle 37 may also be mounted on the first cooling stage 30. The inlet baffle 37 is cooled to the same temperature as the radiation shield 36, enabling the condensation of so-called Type I gases (gases such as water vapor that condense at higher temperatures) on its surface.

[0030] To provide an ultra-low temperature surface for condensing type II gases (e.g., gases that condense at lower temperatures, such as argon and nitrogen), the cryogenic plate 38 is thermally connected to the second cooling stage 34 and cooled to a second cooling temperature. Furthermore, to adsorb type III gases (e.g., non-condensable gases such as hydrogen), at least a portion of the surface of the cryogenic plate 38 (e.g., the surface opposite to the cryogenic pump inlet 17) is provided with materials such as activated carbon or other adsorbents. Gas entering the radiation shield 36 from outside the cryogenic pump 10 through the cryogenic pump inlet 17 is captured onto the cryogenic plate 38 by condensation or adsorption. Various known configurations can be appropriately employed regarding the arrangement and shape of the radiation shield 36 and the cryogenic plate 38; therefore, detailed descriptions are omitted here.

[0031] The cryogenic pump container 16 has a container body 16a and a refrigerator housing 16b. The cryogenic pump container 16 is a vacuum container designed to maintain a vacuum during vacuum exhaust operation of the cryogenic pump 10 and to withstand ambient pressure (e.g., atmospheric pressure). The container body 16a has a cylindrical shape with a cryogenic pump inlet 17 at one end and a closed end. A radiation shield 36 is housed within the container body 16a, and as described above, a cryogenic plate 38 is housed within the radiation shield 36 along with the second cooling stage 34. One end of the refrigerator housing 16b is joined to the container body 16a, and the other end is fixed to the room temperature section 26 of the refrigerator 14. The refrigerator 14 is inserted into the refrigerator housing 16b, and a first cylinder 28 is housed therein.

[0032] In this embodiment, the cryogenic pump 10 is a so-called horizontal cryogenic pump in which the refrigerator 14 is disposed on the side of the container body 16a. A refrigerator insertion port is provided on the side of the container body 16a, and the refrigerator housing 16b is connected to the side of the container body 16a through the refrigerator insertion port. Similarly, adjacent to the refrigerator insertion port of the container body 16a, a hole for the refrigerator 14 to pass through is also provided on the side of the radiation shield 36. The second cylinder 32 and the second cooling platform 34 of the refrigerator 14 are inserted into the radiation shield 36 through these holes, and the radiation shield 36 is thermally connected to the first cooling platform 30 around the holes on its side.

[0033] The cryogenic pump 10 can be positioned in various orientations within the vacuum chamber 100 at the site of use. As an example, the cryogenic pump 10 can be positioned in the lateral orientation shown in the figure (i.e., with the cryogenic pump inlet 17 facing upwards). In this case, the bottom of the container body 16a is positioned below the cryogenic pump inlet 17, and the refrigerator 14 extends horizontally.

[0034] The cryogenic pump 10 is equipped with a first temperature sensor 40 for measuring the temperature of the first cooling stage 30 and a second temperature sensor 42 for measuring the temperature of the second cooling stage 34.

[0035] The first temperature sensor 40 can also be mounted on the first cooling platform 30. The second temperature sensor 42 can also be mounted on the second cooling platform 34. The temperature of the first cooling platform 30 measured by the first temperature sensor 40 can be considered as the temperature of the radiation shield 36, and the temperature of the second cooling platform 34 measured by the second temperature sensor 42 can be considered as the temperature of the cryogenic plate 38. Therefore, the first temperature sensor 40 can measure the temperature of the radiation shield 36 and output a first measured temperature signal representing the measured temperature of the radiation shield 36. The second temperature sensor 42 can measure the temperature of the cryogenic plate 38 and output a second measured temperature signal representing the measured temperature of the cryogenic plate 38. Furthermore, a pressure sensor 44 is provided inside the cryogenic pump container 16. The pressure sensor 44 is provided, for example, in the refrigerator housing 16b, and can measure the internal pressure of the cryogenic pump container 16 and output a measured pressure signal representing the measured pressure.

[0036] Furthermore, the cryogenic pump 10 includes a cryogenic pump controller 46 for controlling the cryogenic pump 10. The cryogenic pump controller 46 may also be integrated with the cryogenic pump 10. For example, the cryogenic pump controller 46 may be installed in the room temperature section 26. Alternatively, the cryogenic pump controller 46 may be configured as a control device separate from the cryogenic pump 10. Alternatively, a part of the cryogenic pump controller 46 may be integrated with the cryogenic pump 10, while another part of the cryogenic pump controller 46 may be separately installed from the cryogenic pump 10 and electrically connected to each other.

[0037] During the vacuum exhaust operation of the cryogenic pump 10, the cryogenic pump controller 46 can control the refrigerator 14 based on the cooling temperature of the radiation shield 36 and / or the cryogenic plate 38. The cryogenic pump controller 46 can be connected to the first temperature sensor 40 to receive a first measured temperature signal from the first temperature sensor 40, and connected to the second temperature sensor 42 to receive a second measured temperature signal from the second temperature sensor 42.

[0038] Furthermore, the cryogenic pump controller 46 can function as a regeneration controller for the cryogenic pump 10. During the regeneration operation of the cryogenic pump 10, the cryogenic pump controller 46 can control the refrigerator 14, the coarse extraction valve 18, the main body purge valve 20, the discharge valve 22, and the discharge purge valve 24 based on the pressure inside the cryogenic pump container 16 (or, as needed, based on the temperature of the cryogenic plate 38 and the pressure inside the cryogenic pump container 16). The cryogenic pump controller 46 can also be connected to the pressure sensor 44 to receive the measured pressure signal from the pressure sensor 44.

[0039] Regarding the internal structure of the controller, in terms of hardware, it is implemented by components or circuits, such as a computer's CPU or memory; in terms of software, it is implemented by computer programs, etc., but appropriately depicted in the diagram as functional modules implemented through their cooperation. Those skilled in the art should understand that these functional modules can be implemented in various forms through a combination of hardware and software.

[0040] For example, the controller can be implemented through a combination of a processor (hardware) such as a CPU (Central Processing Unit) or a microcomputer and a software program executed by the processor (hardware). The software program can be a computer program used to enable the controller to perform vacuum exhaust operation and / or regeneration operation of the cryogenic pump 10.

[0041] A roughing valve 18 is disposed in the cryogenic pump container 16, such as the refrigerator housing 16b. The roughing valve 18 is connected to a roughing pump (not shown) disposed outside the cryogenic pump 10. The roughing pump is a vacuum pump used to evacuate the cryogenic pump 10 to its operating start pressure. When the roughing valve 18 is opened under the control of the cryogenic pump controller 46, the cryogenic pump container 16 is connected to the roughing pump; when the roughing valve 18 is closed, the cryogenic pump container 16 is disconnected from the roughing pump. By opening the roughing valve 18 and activating the roughing pump, the cryogenic pump 10 can be depressurized.

[0042] The main purge valve 20 is capable of supplying purge gas to the container body 16a of the cryogenic pump container 16 (referred to as "main purge"). As an example configuration, the main purge valve 20 is provided in the cryogenic pump container 16, such as the container body 16a. Furthermore, the main purge valve 20 is connected to a purge gas source 48 or a purge gas supply device provided outside the cryogenic pump 10.

[0043] When the main purge valve 20 is opened under the control of the cryogenic pump controller 46, purge gas is supplied from the purge gas source 48 to the cryogenic pump container 16. When the main purge valve 20 is closed, the supply of purge gas to the cryogenic pump container 16 is blocked. By opening the main purge valve 20 and introducing purge gas into the cryogenic pump container 16, the cryogenic pump 10 can be pressurized. Furthermore, the cryogenic pump 10 can be heated from ultra-low temperature to room temperature or a higher temperature. Alternatively, as described later, by adjusting the flow rate of the purge gas through the main purge valve 20, purge gas can be supplied to the cryogenic pump 10 while maintaining the pressure and temperature within the cryogenic pump 10, or suppressing a significant rise in these pressures.

[0044] The purge gas can be, for example, nitrogen or other dry gas, and its temperature can be adjusted to, for example, room temperature (above 0°C, e.g., 15°C to 30°C), or heated to a temperature higher than room temperature (e.g., below 50°C or 80°C). Alternatively, the purge gas temperature can be cooled to a temperature lower than room temperature (e.g., below 0°C). Regarding the cooling of the purge gas, as described later, supplying purge gas to the cryogenic pump container 16 during the cooling operation of the refrigerator 14 helps to suppress the temperature rise of the cryogenic plate 38.

[0045] In this embodiment, the following references are made. Figure 3 and Figure 4 The main purge valve 20 may include a main valve 60 and a pilot valve 70.

[0046] A discharge valve 22 is provided in the cryogenic pump container 16, such as the refrigerator housing 16b. The discharge valve 22 serves as the outlet of the cryogenic pump container 16 to discharge fluid from the interior of the cryogenic pump 10 to the outside. The discharge valve 22 is also the inlet of the discharge line 50, described later. When the discharge valve 22 is opened under the control of the cryogenic pump controller 46, fluid is discharged from the cryogenic pump container 16; when the discharge valve 22 is closed, the discharge of fluid from the cryogenic pump container 16 is stopped. The fluid discharged from the discharge valve 22 is primarily gas, but can also be liquid or a gas-liquid mixture. The discharge valve 22 can be, for example, a normally closed control valve.

[0047] Furthermore, the discharge valve 22 can function as a vent valve or a safety valve, or it can be configured to open mechanically when subjected to a predetermined pressure differential. In this case, if the internal pressure of the cryogenic pump becomes high for some reason, the discharge valve 22 opens mechanically without control. Therefore, the internal high pressure can be released to the discharge line 50.

[0048] The purge valve 24 is capable of supplying purge gas to the purge line 50 (referred to as "purge"). As an exemplary configuration, the purge valve 24 and the purge valve 22 can be separately configured, with the purge valve 24 connected downstream of the purge valve 22 via piping. Alternatively, the purge valve 24 can be integrated with the purge valve 22 to supply purge gas to the purge valve 22 or its downstream location. The purge valve 24 can be located in the cryogenic pump container 16, such as the refrigerator housing 16b. The purge valve 24 is connected to a purge gas source 48 or another purge gas source.

[0049] When the purge valve 24 is opened under the control of the cryogenic pump controller 46, purge gas is supplied from the purge gas source 48 to the discharge line 50. When the purge valve 24 is closed, the supply of purge gas to the discharge line 50 is blocked. Furthermore, the purge gas supplied from the purge valve 24 is typically the same type of gas as the purge gas supplied from the main purge valve 20 (e.g., nitrogen), but a suitable different type of gas may also be used.

[0050] A discharge line 50 is provided to discharge the discharge fluid from the cryogenic pump 10 to the treatment device 52, and is connected to the discharge valve 22 and the discharge purge valve 24 at its upstream end and to the treatment device 52 at its downstream end.

[0051] The treatment device 52 may be, for example, a decontamination device that treats hazardous gases (e.g., hydrogen, or other explosive gases, or other corrosive or toxic gases such as fluorine-based or halogen-based gases) contained in the discharged fluid to generate harmless gases, or it may be a treatment device that reduces the hazard of hazardous gases. Known decontamination devices or treatment devices can be appropriately used as the treatment device 52, therefore detailed descriptions are omitted here.

[0052] By continuously operating the cryogenic pump 10 under vacuum, gas is accumulated inside the cryogenic pump 10. In order to discharge the accumulated gas to the outside, the cryogenic pump 10 needs to be regenerated. The regeneration of the cryogenic pump 10 typically includes a heating process, a discharge process, and a cooling process.

[0053] A gate valve 102 is provided between the cryogenic pump 10 and the vacuum chamber 100 that is being evacuated. When the regeneration of the cryogenic pump 10 begins, the gate valve 102 is closed, and the cryogenic pump 10 is separated from the vacuum chamber 100 (the internal volume of the cryogenic pump 10 is isolated from the vacuum chamber 100).

[0054] The heating process includes the following steps: heating the cryogenic pump 10 to the boiling point of the hazardous gas captured by the cryogenic pump 10 or a higher temperature; and further heating the cryogenic pump 10 to the regeneration temperature. The hazardous gas is typically, for example, a type 2 or type 3 gas, with a boiling point, for example, below 100 K. The regeneration temperature is, for example, room temperature or a temperature above room temperature. Therefore, in most cases, the hazardous gas is re-vaporized in the first half of the heating process, especially after the initial start, discharged from the cryogenic pump 10, and flows into the processing unit 52. The hazardous gas is removed from the cryogenic pump 10 during the heating process.

[0055] The heat source for heating is, for example, a refrigerator 14. The refrigerator 14 is capable of heating operation (so-called reverse heating). That is, the refrigerator 14 is configured to generate insulated compression of the working gas when the drive mechanism 26a operates in the opposite direction to the cooling operation (i.e., the motor driving the refrigerator 14 rotates in the opposite direction). The refrigerator 14 heats the first cooling stage 30 and the second cooling stage 34 using the heat of compression thus obtained. The radiation shield 36 and the cryogenic plate 38 are heated by the first cooling stage 30 and the second cooling stage 34, respectively. Furthermore, the purge gas supplied from the main purge valve 20 to the cryogenic pump container 16 can also contribute to the heating of the cryogenic pump 10. Alternatively, a heating device such as an electric heater can be provided on the cryogenic pump 10. For example, an electric heater that can be controlled independently of the operation of the refrigerator 14 can be installed on the first cooling stage 30 and / or the second cooling stage 34 of the refrigerator 14.

[0056] In the discharge process, the gas captured by the cryogenic pump 10 is re-vaporized or liquefied and discharged as a gas, liquid, or gas-liquid mixture through the discharge line 50 or through the roughing valve 18. Since type 2 and type 3 gases can be easily discharged from the cryogenic pump 10 during the heating process, the discharge process is primarily for discharging type 1 gases. Once the discharge process is complete, the cooling process begins. In the cooling process, the cryogenic pump 10 is cooled again to the ultra-low temperature required for vacuum exhaust operation. If this regeneration is complete, the gate valve 102 is reopened, and the cryogenic pump 10 can restart vacuum exhaust operation.

[0057] In semiconductor manufacturing processes, hazardous gases with various dangers, such as explosiveness, corrosiveness, and toxicity, are sometimes used. If the cryogenic pump 10 experiences an unexpected temperature rise for some reason, the hazardous gas stored in the cryogenic pump 10 may re-vaporize, and the concentration of the hazardous gas within the cryogenic pump 10 may increase.

[0058] Such unsafe conditions can occur, for example, due to power outages or other anomalies. The cryogenic pump 10, for example, can operate under the control of the cryogenic pump controller 46 via a mains power source (not shown) such as a commercial power supply, performing operations such as vacuum exhaust and regeneration. However, when the mains power fails, the operation of the cryogenic pump 10 may cease. In the event of a power outage, especially if restoration takes time, the cryogenic pump 10 may heat up due to heat input from the surrounding environment.

[0059] To address unsafe conditions, a so-called safety purging of the cryogenic pump 10 can be performed automatically. During safety purging, the main purging valve 20 is opened, and purging gas is supplied from the purging gas source 48 to the cryogenic pump container 16 through the main purging valve 20. Gases, such as hazardous gases, that have vaporized within the cryogenic pump container 16 are discharged along with the purging gas through the discharge valve 22 to the discharge line 50. In this way, the concentration of hazardous gases within the cryogenic pump 10 can be reduced to a safe level.

[0060] One of the main uses of the cryogenic pump 10 is to purge the vacuum from the ion implantation device. At this time, the cryogenic pump 10 primarily stores hydrogen. By performing a safety purging during a power outage, even if the hydrogen re-vaporizes within the cryogenic pump 10, it can be discharged from the cryogenic pump 10 along with the purging gas. In this way, the hydrogen concentration within the cryogenic pump 10 can be reduced to a safe level, for example, below the explosive limit of hydrogen (approximately 4%).

[0061] The main purge valve 20 can be a normally open valve. Therefore, when the power supply to the main purge valve 20 is interrupted, the main purge valve 20 returns to its normally open state. Thus, in the event of a power outage, the main purge valve 20 automatically opens, reliably performing safety purging.

[0062] During safety purging, the purge valve 24 can be opened to supply purging gas to the purge line 50. This purges the purge line 50 and rapidly reduces the concentration of hazardous gas within it to a safe level. For reliable operation, the purge valve 24 can also be a normally open valve.

[0063] When the cryogenic pump controller 46 is operational, the main purge valve 20 can be opened under the control of the cryogenic pump controller 46, and a safety purge can be performed. At this time, the discharge purge valve 24 can also be opened by the cryogenic pump controller 46.

[0064] Figure 3 and Figure 4 This diagram schematically shows an exemplary configuration of the purge valve of the cryogenic pump 10 according to the embodiment. As shown, the main purge valve 20 includes a main valve 60 and a pilot valve 70. Furthermore, as described later, the main purge valve 20 may also include a check valve 75.

[0065] The main valve 60 is configured to close by fluid supply from fluid source 54 to block purge gas, and open by fluid discharge to supply purge gas. The pilot valve 70 is configured to switch between a first state of fluid supply from fluid source 54 to main valve 60 and a second state of fluid discharge from main valve 60. The first state is shown in… Figure 3 The second state is shown in Figure 4 .

[0066] Therefore, when pilot valve 70 is in the first state, main valve 60 is closed, blocking the supply of purge gas to cryogenic pump container 16. Conversely, when pilot valve 70 is in the second state, main valve 60 is open, supplying purge gas to cryogenic pump container 16. Figure 4 In the image, the purge gas flow is schematically shown by arrow 76.

[0067] The main valve 60 can be a so-called pneumatic valve. Therefore, the fluid supplied to and discharged from the main valve 60 via the pilot valve 70 can be air, such as compressed air. The fluid source 54 can be an air source, such as a compressed air source.

[0068] The pilot valve 70 can be externally piloted or disposed outside and connected to the main valve 60. In this case, the pilot valve 70 can be positioned in a fixed position relative to the main valve 60. For example, both the main valve 60 and the pilot valve 70 can be installed in the cryogenic pump container 16 or connected to each other via piping 68 for fluid supply and discharge. Alternatively, the pilot valve 70 can be internally piloted and can be assembled within the main valve 60.

[0069] As an example configuration, the main valve 60 includes a valve housing 62 and a valve piston 64. The valve housing 62 has a purge gas inlet 62a, a purge gas outlet 62b, and a fluid port 62c. The purge gas inlet 62a is connected to a purge gas source 48, and the purge gas outlet 62b is connected to a cryogenic pump container 16. As described later, the purge gas inlet 62a and the purge valve outlet 62b are opened or closed by the movement of the valve piston 64. The fluid port 62c is connected to a fluid source 54 via a pilot valve 70. The fluid port 62c is not opened or closed by the movement of the valve piston 64. The fluid port 62c is always open.

[0070] The valve piston 64 is configured to reciprocate within the valve housing 62. The volume within the valve housing 62 is divided by the valve piston 64 into two chambers: a purge gas flow path 65 and a fluid chamber 66. The purge gas flow path 65 has a purge gas inlet 62a and a purge gas outlet 62b, and the fluid chamber 66 has a fluid port 62c.

[0071] Furthermore, the valve piston 64 is connected to the valve housing 62 via a return spring 67. The return spring 67 is provided to make the main valve 60 a normally open valve. That is, the return spring 67 stores pressure on the valve piston 64 so that the purge gas flow path 65 is normally open.

[0072] Pilot valve 70 has a supply port 71, a discharge port 72, and a main valve port 73. Pilot valve 70 can be a three-way valve. Supply port 71 is connected to fluid source 54. As shown, supply port 71 can also be connected to fluid source 54 via check valve 75. Discharge port 72 can be opened to the surrounding environment or connected to a fluid recovery tank (not shown). Main valve port 73 is connected to fluid port 62c of main valve 60 via piping 68.

[0073] In the first state of pilot valve 70, such as Figure 3 As shown, the supply port 71 is connected to the main valve port 73. In the first state, the discharge port 72 is blocked. Furthermore, in the second state of the pilot valve 70, as... Figure 4 As shown, discharge port 72 is connected to main valve port 73. In the second state, supply port 71 is blocked.

[0074] The pilot valve 70 may be equipped with a solenoid valve that switches between the first state and the second state. In this embodiment, the pilot valve 70 is normally in the second state. That is, when power is supplied, the pilot valve 70 is driven to the first state, and when power is lost or when there is no power supply, it returns to the second state.

[0075] Under safe conditions where no power outages or other abnormalities occur, such as during vacuum exhaust operation of the cryogenic pump 10, the pilot valve 70 is powered and in state 1. For example... Figure 3 As shown, in the first state, pilot valve 70 connects fluid source 54 to fluid chamber 66 of main valve 60. As schematically indicated by arrow 77, fluid is supplied from fluid source 54 to fluid chamber 66 through pilot valve 70. The fluid pressure in fluid chamber 66 increases to a level higher than the pressure in purge gas flow path 65. Due to the fluid pressure in fluid chamber 66, as schematically indicated by arrow 78, valve piston 64 moves in a manner that reduces the volume of purge gas flow path 65, blocking purge gas inlet 62a and purge gas outlet 62b. Main valve 60 is closed, and the supply of purge gas from purge gas source 48 to cryogenic pump container 16 is interrupted. Thus, main purge valve 20 is closed by power supply. By closing main purge valve 20, vacuum is maintained in cryogenic pump container 16.

[0076] On the other hand, in an unsafe condition, pilot valve 70 switches from state 1 to state 2. For example, during a power outage, power cannot be supplied to pilot valve 70, therefore pilot valve 70 returns to state 2 from state 1. Figure 4As shown, in the second state, pilot valve 70 connects discharge port 72 to fluid chamber 66 of main valve 60. Fluid source 54 is separated from fluid chamber 66. As schematically shown by arrow 79, fluid is discharged from fluid chamber 66 to the outside through pilot valve 70, and the fluid pressure in fluid chamber 66 is released. By the restoring force of return spring 67, valve piston 64 moves in a manner that increases the volume of purge gas flow path 65, through which purge gas inlet 62a and purge gas outlet 62b are connected. Thus, main valve 60, i.e., main purge valve 20, opens, and as schematically shown by arrow 76, purge gas is supplied from purge gas source 48 to cryogenic pump container 16. Main purge valve 20 is capable of performing safe purging.

[0077] The fluid source 54 is typically a gas cylinder containing fluid. As the fluid is consumed, the residual pressure in the gas cylinder gradually decreases, so the user of the cryogenic pump 10 needs to replace the empty gas cylinder with a new one as needed. If the pump continues to be used with insufficient residual pressure in the gas cylinder, eventually, the fluid source 54 will be unable to provide the fluid pressure to the fluid chamber 66 required to switch the pilot valve 70 to its first state. Alternatively, if the piping connected to the fluid source 54 for fluid supply is incorrectly disconnected, the fluid supply to the pilot valve 70 will also be interrupted.

[0078] like Figure 5 As shown, if the fluid supply from fluid source 54 to pilot valve 70 is interrupted when fluid source 54 is directly connected (i.e., without check valve 75), the fluid pressure in fluid chamber 66 will drop, or fluid will be discharged from fluid chamber 66, as schematically indicated by arrow 79. This causes the main valve 60 to open, as if pilot valve 70 had returned to state 2, and purge gas will be supplied to cryogenic pump container 16, as schematically indicated by arrow 76. If such an unintended safety purge occurs, the vacuum environment used for the vacuum process is compromised, necessitating process interruption. Responding to restart the process requires considerable time and expense, and is therefore undesirable.

[0079] Therefore, the main purge valve 20 can be configured to restrict fluid discharge from the main valve 60 when the fluid supply from the fluid source 54 is interrupted in the first state of the pilot valve 70. In this way, when the fluid supply from the fluid source 54 to the fluid chamber 66 is interrupted due to insufficient pressure in the fluid source 54, accidental disconnection of the piping, etc., by restricting the fluid discharge from the main valve 60, the fluid pressure in the fluid chamber 66 can be maintained, and the first state of the pilot valve 70 can be continued. Therefore, unintended safety purging as described above can be prevented. On the other hand, when safety purging is required, the execution of safety purging is not hindered. By switching the pilot valve 70 from the first state to the second state, fluid can be discharged from the fluid chamber 66, the main valve 60 can be opened, and safety purging can be performed.

[0080] As an exemplary configuration for responding to unintended safety purging, a check valve 75 can be used. As shown, the check valve 75 is disposed between the fluid source 54 and the supply port 71 of the pilot valve 70. The check valve 75 connects the fluid source 54 and the supply port 71 to allow forward fluid flow from the fluid source 54 to the supply port 71 and prevent reverse flow of fluid from the supply port 71 toward the fluid source 54.

[0081] The check valve 75 allows fluid to flow from the fluid source 54 to the supply port 71, and therefore does not impede the fluid supply from the fluid source 54 to the main valve 60 through the pilot valve 70 in the first state of the pilot valve 70.

[0082] like Figure 6 As shown, when the fluid supply from fluid source 54 to fluid chamber 66 is interrupted, check valve 75 prevents fluid from flowing back from supply port 71 toward fluid source 54, thereby maintaining the fluid pressure in fluid chamber 66 and continuing the first state of pilot valve 70. Therefore, unintended safety purging as described above can be prevented. On the other hand, when safety purging is required, its execution is not hindered. When safety purging is required, by switching pilot valve 70 from the first state to the second state, fluid can be discharged from fluid chamber 66, the main valve 60 can be opened, and safety purging can be performed.

[0083] The check valve 75 can be positioned fixed relative to the pilot valve 70. For example, both the pilot valve 70 and the check valve 75 can be installed in the cryogenic pump container 16 and connected to each other via piping for fluid supply and discharge. This prevents the piping from coming loose due to accidental relative movement of the check valve 75 to the pilot valve 70. Alternatively, the check valve 75 can also be installed at the supply port 71 of the pilot valve 70.

[0084] If the power outage is temporary, for example, if the cryogenic pump 10 has not experienced a temperature rise that would cause gas re-vaporization before the main power is restored, then a safety purging may not necessarily be necessary. Therefore, the cryogenic pump 10 can be equipped with an uninterruptible power supply (UPS) function that can temporarily supply power during a main power outage. Thus, even during a power outage, the cryogenic pump 10 can supply power to the purge valve within the power supply capacity of the UPS function and keep the purge valve closed. The UPS function can be designed to keep the purge valve closed for at least 1 minute or at least 2 minutes. Furthermore, the UPS function can be designed to keep the purge valve closed for a maximum of 10 minutes or a maximum of 5 minutes.

[0085] Figure 7 This diagram schematically shows the power supply system of the purge valve of the cryogenic pump 10 according to the embodiment. As described above, the purge valve, such as the main purge valve 20, may include a main valve 60 and a pilot valve 70.

[0086] As described above, the pilot valve 70 may also include a solenoid valve that is normally in a second state. When the pilot valve 70 is in the second state, if a drive voltage is supplied to the pilot valve 70 from the power supply system, the pilot valve 70 is driven to the first state. Thus, the pilot valve 70 switches from the second state to the first state. When the pilot valve 70 is in the first state, if the supply voltage from the power supply system exceeds the recovery voltage, the pilot valve 70 remains in the first state. When the supply voltage from the power supply system drops below the recovery voltage, the pilot valve 70 returns to the second state from the first state.

[0087] The drive voltage is the rated voltage of the pilot valve 70, such as a 12V or 24V DC voltage. The recovery voltage of the pilot valve 70 is a voltage lower than the drive voltage. For example, the recovery voltage can be less than half of the drive voltage.

[0088] As shown in the figure, the power system includes a main power supply 80, a backup power supply 82 providing uninterruptible power, and a power supply controller 90 controlling both power supplies. The main power supply 80 and the backup power supply 82 are connected to the main purge valve 20 via a power supply line 81. The power supply controller 90 may be included in the cryogenic pump controller 46.

[0089] The main power supply 80 is configured to generate drive power for the pilot valve 70 from an external power source such as a DC power supply. When the main power supply 80 is powered on, the power supply controller 90 operates by receiving power from the main power supply 80 and controls the power supply from the main power supply 80 to the pilot valve 70. The power supply controller 90 can receive a closing command for the main purge valve 20 from the cryogenic pump controller 46, causing the main power supply 80 to supply drive voltage to the pilot valve 70, thereby switching the pilot valve 70 from the second state to the first state and closing the main purge valve 20. Furthermore, the power supply controller 90 can also receive an opening command for the main purge valve 20 from the cryogenic pump controller 46, stopping the power supply from the main power supply 80 to the pilot valve 70, thereby restoring the pilot valve 70 from the first state to the second state and opening the main purge valve 20.

[0090] The backup power supply 82 is connected to the pilot valve 70 via power supply line 81, configured to supply power to the pilot valve 70 in place of the main power supply 80 when the main power supply 80 fails. The backup power supply 82 can also supply power to the pilot valve 70 under the control of the power supply controller 90 when the main power supply 80 fails. Alternatively, the backup power supply 82 can be connected to the power supply controller 90, configured to supply power to the power supply controller 90 in place of the main power supply 80 when the main power supply 80 fails. The power supply controller 90 can be considered as part of the backup power supply 82.

[0091] The backup power supply 82 includes an energy storage element 83. For example, the energy storage element 83 can be a double-layer capacitor (also known as a supercapacitor). Figure 7As shown, the energy storage element 83 can be connected to the power supply controller 90 to supply power to the power supply controller 90 in place of the main power supply 80 when the main power supply 80 fails.

[0092] Furthermore, if the rated voltage of the energy storage element 83 is lower than the recovery voltage of the pilot valve 70, the backup power supply 82 may have multiple energy storage elements 83 connected in series, and the sum of the rated voltages of these multiple energy storage elements 83 may be higher than the recovery voltage of the pilot valve 70. Alternatively, the sum of the rated voltages of these multiple energy storage elements 83 may also be higher than the driving voltage of the pilot valve 70.

[0093] The backup power supply 82 may have a switch 84 between the pilot valve 70 and the energy storage element 83. The switch 84 may also be connected between the power supply line 81 and the energy storage element 83. The switch 84 may be controlled by the power supply controller 90. For example, the power supply controller 90 disconnects the switch 84 and disconnects the energy storage element 83 from the pilot valve 70 when the main power supply 80 is powered on. Furthermore, the power supply controller 90 connects the switch 84 and connects the energy storage element 83 to the pilot valve 70 when the main power supply 80 is de-energized.

[0094] Therefore, when the main power supply 80 fails, power can be supplied to the pilot valve 70 from the energy storage element 83. If the pilot valve 70 is in state 1 when the power failure occurs, it will remain in state 1 as long as the supply voltage from the energy storage element 83 to the pilot valve 70 remains above the recovery voltage. By supplying power to the pilot valve 70, the power stored in the energy storage element 83 is consumed. When the supply voltage from the energy storage element 83 to the pilot valve 70 falls below the recovery voltage, the pilot valve 70 returns to state 2 from state 1.

[0095] Furthermore, the backup power supply 82 may also include a boost circuit 85 between the pilot valve 70 and the energy storage element 83. The boost circuit 85 may be connected in parallel with the switch 84 between the power supply line 81 and the energy storage element 83. The boost circuit 85 may be configured to boost the output voltage of the energy storage element 83 to exceed the recovery voltage of the pilot valve 70, thereby generating a supply voltage to the pilot valve 70. The boost circuit 85 may, for example, be a boost converter.

[0096] Alternatively, the boost circuit 85 can also be a buck-boost circuit, such as a buck-boost converter. In this case, the boost circuit 85 can also step down the voltage of the main power supply 80 and supply it to the energy storage element 83 when the energy storage element 83 is being charged by the main power supply 80.

[0097] The boost circuit 85 can be controlled by the power supply controller 90. For example, the power supply controller 90 can be configured to detect the output voltage of the energy storage element 83 and compare the output voltage of the energy storage element 83 with a voltage threshold. The voltage threshold can be equal to the recovery voltage of the pilot valve 70. Alternatively, the voltage threshold can be a voltage value higher than the recovery voltage, for example, a voltage value 0.1V to 1V higher than the recovery voltage.

[0098] The power supply controller 90 can shut down the boost circuit 85 when the output voltage of the energy storage element 83 is above a voltage threshold. At this time, the output voltage of the energy storage element 83 is directly supplied to the pilot valve 70. Since the supply voltage from the energy storage element 83 to the pilot valve 70 is above the recovery voltage, the pilot valve 70 remains in the first state.

[0099] On the other hand, the power supply controller 90 can also activate the boost circuit 85 when the output voltage of the energy storage element 83 is lower than the voltage threshold. At this time, the output voltage of the energy storage element 83 is boosted to above the recovery voltage through the boost circuit 85 and supplied to the pilot valve 70. The pilot valve 70 remains in the first state until the power stored in the energy storage element 83 is exhausted.

[0100] As another example, the boost circuit 85 can also be connected in series with the switch 84 between the power supply line 81 and the energy storage element 83.

[0101] The boost circuit 85 can be configured to detect the output voltage of the energy storage element 83 and compare it with a voltage threshold. When the output voltage of the energy storage element 83 is above the voltage threshold, the boost circuit 85 can directly supply the output voltage of the energy storage element 83 to the pilot valve 70. Alternatively, when the output voltage of the energy storage element 83 is below the voltage threshold, the boost circuit 85 can boost the output voltage of the energy storage element 83 to above the recovery voltage and supply it to the pilot valve 70.

[0102] Thus, the backup power supply 82 can utilize the boost circuit 85 to extend the backup time for supplying power to the pilot valve 70. Alternatively, to achieve an equivalent backup time, the backup power supply 82 can be equipped with a smaller energy storage element 83, which is advantageous.

[0103] By using the boost circuit 85 to extend the backup time, the charging rate of the energy storage element 83 can be reduced. That is, the backup power supply 82 can achieve the same backup time using the energy storage element 83 with a lower charging rate. When the energy storage element 83 is repeatedly charged, a higher charging rate tends to result in a shorter lifespan for the energy storage element 83. Therefore, reducing the charging rate of the energy storage element 83 contributes to its longer lifespan, which is advantageous.

[0104] And, as Figure 7As shown, a storage element monitor 92 may also be provided in the backup power supply 82. The storage element monitor 92 may be part of the power supply controller 90.

[0105] The energy storage element monitor 92 can be configured to monitor the energy storage element 83 by discharging it. The energy storage element monitor 92 and the energy storage element 83 can be connected to each other in such a way as to form a discharge circuit for discharging the energy storage element 83. The energy storage element monitor 92 can also be connected to the energy storage element 83 via a power supply line 81. As an example, the energy storage element monitor 92 can include a constant current circuit that discharges the energy storage element 83 with a constant current. The constant current circuit can be a known constant current circuit.

[0106] The energy storage element monitor 92 can monitor the capacity C(F) of the energy storage element 83. As an example, when the energy storage element 83 discharges through a constant current circuit flowing with a constant current I(A), the capacity C(F) of the energy storage element 83 is expressed by the following formula:

[0107] C = I × T / ΔV

[0108] Here, ΔV (=V1-V2) represents the voltage difference between the discharge start voltage V1 (V) and the discharge end voltage V2 of the energy storage element 83, and T (seconds) represents the time required for the energy storage element 83 to discharge (i.e., the time required for the energy storage element 83 to discharge from the discharge start voltage V1 to the discharge end voltage V2 with a constant current I).

[0109] When the energy storage element 83 discharges into the constant current circuit of the energy storage element monitor 92, the energy storage element monitor 92 measures the constant current I, the voltage difference ΔV, the discharge time T, and calculates the capacity C of the energy storage element 83. In this way, the energy storage element monitor 92 can monitor the capacity C(F) of the energy storage element 83.

[0110] The energy storage element monitor 92 can compare the calculated capacity C with a capacity threshold. If the calculated capacity C exceeds the capacity threshold, the energy storage element monitor 92 can determine that the energy storage element 83 is normal. The energy storage element monitor 92 can output information indicating that the energy storage element 83 is normal. On the other hand, if the calculated capacity C is below the capacity threshold, the energy storage element monitor 92 can determine that the energy storage element 83 is abnormal. The energy storage element monitor 92 can output information indicating that the energy storage element 83 is abnormal (e.g., the capacity of the energy storage element 83 has decreased).

[0111] Thus, the energy storage element monitor 92 can monitor the energy storage element 83 and detect abnormalities. For example, the energy storage element monitor 92 can detect a decrease in the capacity of the energy storage element 83 caused by aging or other reasons.

[0112] The present invention has been described above with reference to embodiments. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and various design changes and modifications are possible, and such modifications are also within the scope of the present invention. The various features described for one embodiment can also be applied to other embodiments. New embodiments resulting from combinations possess the effects of the combined embodiments.

[0113] In the above embodiment, the use of a check valve 75 was described as an example to address unexpected safety purging, but other configurations can also be used. For example, instead of the check valve 75, a flow path resistance, such as a throttling orifice, can be provided between the fluid source 54 and the supply port 71. In this case, when the fluid supply from the fluid source 54 is interrupted in the first state of the pilot valve 70, the flow path resistance can limit the fluid discharge from the main valve 60. This suppresses a sharp drop in fluid pressure in the fluid chamber 66, thereby maintaining the first state of the pilot valve 70 for a certain period and delaying the occurrence of unexpected safety purging.

[0114] Alternatively, a switching valve can be installed between the fluid source 54 and the supply port 71 instead of the check valve 75. In addition to the switching valve, a pressure gauge can be installed to measure the pressure in the fluid chamber 66. When the pressure measured by the pressure gauge is sufficient to maintain the first state of the pilot valve 70, the switching valve can be closed manually or under the control of the cryogenic pump controller 46. Even so, the switching valve, like the check valve 75, can prevent fluid from flowing back from the supply port 71 towards the fluid source 54, thereby maintaining the fluid pressure in the fluid chamber 66 and continuing the first state of the pilot valve 70. When the pilot valve 70 is in the second state, the switching valve can be opened manually or under the control of the cryogenic pump controller 46. In this way, when the pilot valve 70 switches from the second state to the first state, fluid can be supplied from the fluid source 54 to the fluid chamber 66 again through the switching valve.

[0115] In the above embodiment, the case where the main purge valve 20 includes a main valve 60 and a pilot valve 70 has been described as an example. However, it may also have the following configuration: the discharge valve 24 is the same as or replaces the main purge valve 20, and includes a main valve 60 and a pilot valve 70. In this case, the discharge purge valve 24 may be configured to restrict the discharge of fluid from the main valve 60 when the fluid supply from the fluid source 54 is interrupted in the first state of the pilot valve 70.

[0116] According to the embodiments, the present invention has been described using specific statements. However, the embodiments only represent one aspect of the principle and application of the present invention. Many modifications or configuration changes can be made to the embodiments without departing from the spirit of the present invention as defined by the claims.

Claims

1. A cryogenic pump, characterized by, The purge valve is provided with: The purge valve is provided with: The main valve is closed by fluid supply from a fluid source to block purge gas and opened by fluid discharge to supply the purge gas; and The pilot valve switches a first state of supplying the fluid from the fluid source to the main valve and a second state of discharging the fluid from the main valve, The purge valve is configured to limit the discharge of the fluid from the main valve when the fluid supply from the fluid source is interrupted in the first state of the pilot valve.

2. The cryopump according to claim 1, wherein The pilot valve is provided with a supply port connected to the fluid source and a main valve port connected to the main valve, and the supply port and the main valve port are communicated in the first state; The purge valve is provided with a check valve provided between the fluid source and the supply port to prevent backflow of the fluid from the supply port toward the fluid source.

3. A cryopump according to claim 1 or 2, characterised in that, Further provided are: A cryopump container connected to the main valve, The main valve is closed when the pilot valve is in the first state to block the supply of the purge gas to the cryopump container and opened when the pilot valve is in the second state to supply the purge gas to the cryopump container.

4. A cryopump according to claim 1 or 2, characterised in that Further provided are: A backup power source connected to the pilot valve, The pilot valve is provided with a solenoid valve that is restored from the first state to the second state when a supply voltage drops below a restoration voltage, The backup power source is provided with: A charge storage element; and A voltage boosting circuit that boosts an output voltage of the charge storage element to exceed the restoration voltage of the solenoid valve to generate the supply voltage supplied to the solenoid valve.

5. A cryopump according to claim 1 or 2, characterised in that Further provided are: A backup power source connected to the pilot valve, The backup power source is provided with: A charge storage element; and A charge storage element monitor that monitors the charge storage element by discharging the charge storage element.

6. A cryopump, comprising: The purge valve is provided with: The purge valve is provided with: The main valve is closed by fluid supply from a fluid source to block purge gas and opened by fluid discharge to supply the purge gas; and The pilot valve switches a first state of supplying the fluid from the fluid source to the main valve and a second state of discharging the fluid from the main valve, The pilot valve is provided with a solenoid valve that is restored from the first state to the second state when a supply voltage drops below a restoration voltage, The backup power source is connected to the pilot valve and is provided with: A charge storage element; and A voltage boosting circuit that boosts an output voltage of the charge storage element to exceed the restoration voltage of the solenoid valve to generate the supply voltage supplied to the solenoid valve. The purge valve is provided with:

7. A cryopump, characterized by, The purge valve is provided with: The main valve is closed by fluid supply from a fluid source to block purge gas and opened by fluid discharge to supply the purge gas; and The pilot valve switches a first state of supplying the fluid from the fluid source to the main valve and a second state of discharging the fluid from the main valve, The backup power source is connected to the pilot valve and is provided with: A charge storage element; and ​ A storage element monitor monitors a storage element by discharging the storage element.

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