TWI677626B - Compressor unit and cryopump system for cryogenic refrigerator - Google Patents

Abstract

[Problem] The present invention provides a simple method for processing vibration in an inverter-driven compressor unit for a cryogenic refrigerator. [Solution] The compressor unit includes a flow control valve, a compressor inverter (170), and a compressor controller (168) that control the flow of the bypass pipe in accordance with a valve designation signal. The range of usable values of the operating frequency is set in advance in the first operating frequency range from the lower limit value to the first value, and in the second operating frequency range from the second value to the upper limit value, from the first value to the second value. The unused frequency range up to the value includes the natural frequency of the compressor structure. When the target flow rate is the first discharge flow rate and the second discharge flow rate, the compressor controller (168) determines the inverter command signal so that the operating frequency is set in the second operating frequency range, and determines the valve designated signal so that the bypass pipe is bypassed. The flow rate is the same as the differential flow rate minus the target flow rate from the discharge flow rate of the compressor body obtained according to the inverter's command signal.

Description

Compressor unit and cryopump system for cryogenic refrigerator

[0001] The present invention relates to a compressor unit and a cryopump system for a cryogenic refrigerator.

[0002] Conventionally, a vibration suppression technology is known, which is a so-called variable frequency compressor equipped with an inverter and a variable operating frequency. When the detection output of the vibration sensor is large, the compressor is changed. Operating frequency. [Prior Art Document] [Patent Document] [0003] [Patent Document 1] Japanese Patent Laid-Open No. 2001-317470

[Problems to be Solved by the Invention] 0004 [0004] There is known an extremely low temperature system including an extremely low temperature refrigerator and a compressor unit for supplying an operating gas to the refrigerator. As an example of an extremely low temperature system, a system including an extremely low temperature device (for example, a cryopump) using an extremely low temperature refrigerator as a cooling source is also known. [0005] In an extremely low temperature system, a target pressure value and a pressure measurement value may be used to control the operating frequency of the compressor unit so that, for example, the differential pressure between the high-pressure side and the low-pressure side of the working gas of the refrigerator is consistent with the set value. Such control can help reduce the power consumption of the system because it can provide the target gas flow required by the refrigerator at the optimal (minimum) operating frequency. [0006] It is assumed that the natural frequency of the mechanical structure such as the piping of the compressor unit is included in the operating frequency range used in the inverter. The compressor unit in operation itself becomes a vibration source. If the value of the operating frequency is close to the natural frequency, resonance may occur in the mechanical structure of the compressor unit. Excessive vibration and noise, fatigue of structural parts are not expected. [0007] In order to avoid such problems, it is better to prohibit the use of a value close to the natural frequency. However, this means that when the value of the optimal operating frequency is close to the natural frequency, this value is not used instead of using a value far from the natural frequency. When the operating frequency is changed to a smaller value, the supply flow rate from the compressor unit may be insufficient relative to the flow rate of the operating gas required for the refrigerator. When the operating frequency is changed to a larger value, the power consumption of the compressor unit increases, leading to the disadvantage that the advantage of reducing the power consumption controlled by the inverter cannot be obtained sufficiently. [0008] As a fundamental solution, you can also consider changing the design of the compressor unit so that the natural frequency of the mechanical structure part is not included in the operating frequency range used. However, such design changes take time and effort. [0009] One of the exemplary objects of one aspect of the present invention is to provide a simple method for dealing with vibration of an inverter-driven compressor unit used in a cryogenic refrigerator. [Means for Solving the Problems] [0010] According to one aspect of the present invention, a compressor unit for a cryogenic refrigerator is provided. The compressor unit includes a compressor structure unit including a compressor main body that compresses and discharges an operating gas of a cryogenic refrigerator, a compressor motor that has a variable operating frequency and operates the compressor main body, and is connected to the compressor. High pressure piping from which the main body causes the operating gas to be discharged from the compressor main body, low pressure piping connected to the compressor main body so that the operating gas is sucked into the compressor main body, bypassing the compressor main body and connecting the high pressure piping to the low pressure pipe, A flow control valve provided in the bypass pipe so as to control the flow of the bypass pipe according to a valve designated signal; a compressor inverter, which controls the operating frequency of the compressor motor according to a frequency converter command signal; and a compressor controller, which It is composed of the designated signal of the decision valve and the command signal of the inverter, so that the operating gas is supplied from the compressor unit to the cryogenic refrigerator at the target flow rate. The range of values that can be used for the operating frequency is limited in advance to the first operating frequency interval from the lower limit value greater than zero to the first value, and the second operating frequency interval from the second value to the upper limit value. The second value is greater than The first value. The first value and the second value are determined so that the non-use frequency range from the first value to the second value includes at least one natural frequency with respect to at least a part of the compressor structure portion. The lower limit value, the first value, the second value, and the upper limit value of the operating frequency correspond to the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge flow rate of the compressor body, respectively. When the target flow rate is between the first discharge flow rate and the second discharge flow rate, the compressor controller determines the frequency converter command signal so that the operating frequency is set in the second operating frequency range, and determines the valve designated signal so that the bypass pipe is bypassed. The flow rate is the same as the differential flow rate minus the target flow rate from the discharge flow rate of the compressor body obtained according to the aforementioned inverter command signal. [0011] According to this aspect, the non-use interval of the operating frequency is determined so as to include the natural frequency of the compressor structure portion, and therefore, it is difficult to generate resonance in the compressor structure portion due to the operation of the compressor body. In addition, the inverter command signal is determined so that the operating frequency is set in the second operating frequency range. Therefore, the total flow rate of the operating gas added with the remaining flow rate (the above-mentioned differential flow rate) to the target flow rate is discharged from the compressor body to a high pressure. Piping. The valve designation signal is determined so that the flow rate of the bypass pipe is equal to the remaining flow rate. Therefore, the operating gas is recovered from the high-pressure pipe to the low-pressure pipe, and the compressor unit can supply the operating gas to the cryogenic refrigerator at the target flow rate. [0012] When the target flow rate is between the first discharge flow rate and the second discharge flow rate, the compressor controller can take the second value of the operating frequency to determine the inverter command signal. [0013] When the target flow rate is between the lower limit discharge flow rate and the first discharge flow rate, the compressor controller may determine the frequency converter command signal so that the operation frequency is set in the first operation frequency interval, and may determine the valve designation signal so that The flow control valve is closed. In the case where the target flow rate is between the second discharge flow rate and the upper limit discharge flow rate, the compressor controller can determine the frequency converter command signal so that the operating frequency is set in the second operating frequency range, and can determine the valve designated signal to enable flow control The valve is closed. [0014] In the case where the target flow rate is between zero and the lower limit discharge flow rate, the compressor controller can determine the frequency converter command signal by using the lower limit value of the operating frequency, and the flow rate of the bypass pipe can be consistent with the differential flow rate. Determines the valve designation signal. [0015] When the operating frequency is switched from the first value to the second value, the compressor controller can smooth the valve designated signal and / or the inverter command signal. [0016] According to an aspect of the present invention, the cryopump system includes a cryopump including a cryogenic plate and an ultra-low temperature refrigerator for cooling the cryogenic plate, and a compressor unit including: an ultra-low temperature refrigerator The compressor main body that compresses and discharges the operating gas, a compressor motor that has a variable operating frequency and causes the compressor main body to operate, and a high-pressure pipe connected to the compressor main body so that the operating gas is discharged from the compressor main body and is connected to The compressor main body causes the actuating gas to be sucked into the low-pressure piping of the compressor main body, bypasses the compressor main body and connects the high-pressure piping to the low-pressure piping, and a bypass pipe is provided in the bypass piping so that a signal is designated according to a valve. A flow control valve that controls the flow of the bypass pipe; a compressor inverter that controls the aforementioned operating frequency of the compressor motor according to a command signal from the inverter; and a controller that determines the designated signal of the valve and the aforementioned Inverter command signal, so that the operating gas is supplied from the compressor unit at the target flow rate The range up to the value that the cryogenic freezer operating frequency can adopt is limited in advance to a first operating frequency range from a lower limit value greater than zero to a first value, and a second operating frequency from a second value to an upper limit value. Interval, the second value is greater than the first value. The first value and the second value are determined so that the non-use frequency range from the first value to the second value includes at least one natural frequency with respect to at least a part of the compressor structure portion. The lower limit value, the first value, the second value, and the upper limit value of the operating frequency correspond to the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge flow rate of the compressor body, respectively. When the target flow rate is between the first discharge flow rate and the second discharge flow rate, the controller determines the frequency converter command signal so that the operating frequency is set in the second operating frequency range, and determines the valve designated signal so that the flow rate of the bypass pipe It is consistent with the differential flow rate minus the target flow rate from the discharge flow rate of the compressor body obtained according to the aforementioned inverter command signal. [0017] In addition, a method, an apparatus, a system, and the like, which replace any combination of the above constituent elements or the constituent elements or expressions of the present invention with each other, are equally effective as aspects of the present invention. [Effects of the Invention] [0018] According to the present invention, it is possible to provide a simple method for processing vibration in a compressor unit driven by an inverter used in a cryogenic refrigerator.

[0020] Hereinafter, referring to the drawings, a detailed description of the mode for implementing the present invention will be given. In addition, in the description, the same elements are denoted by the same reference numerals, and repeated description is appropriately omitted. In addition, the structures described below are examples, and are not intended to limit the scope of the present invention. In the following description, in the drawings to be referred to, the sizes and thicknesses of the respective constituent members are for convenience of explanation, and the actual dimensions and proportions are not necessarily shown. [0021] FIG. 1 is a diagram schematically showing an overall configuration of a cryopump system 1000 according to an embodiment of the present invention. The cryopump system 1000 is used for vacuum evacuation of the vacuum device 300. The vacuum device 300 is a vacuum processing device that processes an object in a vacuum environment, and is, for example, an ion implantation device or a sputtering device used in a semiconductor manufacturing process. [0022] The cryopump system 1000 includes a plurality of cryopumps 10. These cryopumps 10 are installed in one or a plurality of vacuum chambers (not shown) of the vacuum device 300, and are used to increase the degree of vacuum inside the vacuum chamber to a level required by a desired process. The cryopump 10 operates according to a control amount determined by a cryopump controller (hereinafter, also referred to as a CP controller) 100. For example, a high vacuum degree of about 10-5Pa to 10-8Pa can be achieved in a vacuum chamber. In the example shown in the figure, the cryopump system 1000 includes 11 cryopumps 10. The plurality of cryopumps 10 may be cryopumps having the same exhaust performance, or cryopumps having different exhaust performances. [0023] The cryopump system 1000 includes a CP controller 100. The CP controller 100 controls the cryopump 10 and the compressor units 102 and 104. The CP controller 100 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for storing data and executing programs, an input / output interface, and a memory device. The CP controller 100 is also configured to be able to communicate with a main controller (not shown) for controlling the vacuum device 300. The main controller of the vacuum device 300 may also be referred to as a controller that integrates various constituent elements of the vacuum device 300 including the cryopump system 1000. [0024] The CP controller 100 is configured differently from the cryopump 10 and the compressor units 102 and 104. The CP controller 100 is connected to the cryopump 10 and the compressor units 102 and 104 so that they can communicate with each other. The cryopump 10 is provided with an IO module 50 (see FIG. 4) for communicating with the CP controller 100 for processing input and output. The CP controller 100 and each IO module 50 are connected by a control communication line. The control communication line between the cryopump 10 and the CP controller 100 and the control communication line between the compressor units 102 and 104 and the CP controller 100 are shown by dotted lines in FIG. 1. The CP controller 100 may be integrated with any of the cryopump 10 or the compressor units 102 and 104. [0025] The CP controller 100 may be composed of a single controller, or may include a plurality of controllers each performing the same or different functions. For example, the CP controller 100 may include a compressor controller which is installed in each compressor unit and determines the control amount of each compressor unit, and a cryopump controller which integrates a cryopump system. [0026] The cryopump system 1000 includes a plurality of compressor units including at least a first compressor unit 102 and a second compressor unit 104. The compressor unit is provided to circulate the operating gas in a closed fluid circuit including the cryopump 10. The compressor unit recovers the working gas from the cryopump 10 and compresses it, and then sends it to the cryopump 10 again. The compressor unit is far from the vacuum device 300 or is provided near the vacuum device 300. The compressor unit operates according to a control amount determined by the compressor controller 168 (see FIG. 4). Alternatively, it operates in accordance with a control amount determined by the CP controller 100. [0027] Hereinafter, a cryopump system 1000 having two compressor units 102 and 104 will be described as a representative example, but the present invention is not limited to this. A cryopump system 1000 in which three or more compressor units are connected in parallel with a plurality of cryopumps 10 in the same manner as those of the compressor units 102 and 104 may also be configured. In addition, the cryopump system 1000 shown in FIG. 1 includes a plurality of cryopumps 10 and compressor units 102 and 104, but the cryopump 10 or the compressor units 102 and 104 may be provided as a single unit. [0028] The plurality of cryopumps 10 and the plurality of compressor units 102 and 104 are connected by operating a gas piping system 106. The piping system 106 is configured to be connected in parallel with the plurality of cryopumps 10 and the plurality of compressor units 102 and 104 so that the operating gas flows between the plurality of cryopump 10 and the compressor units 102 and 104. Through the piping system 106, each compressor unit of the plurality of compressor units is connected in parallel to one cryopump 10, and each cryopump of the plurality of cryopumps 10 is connected in parallel to one compressor unit. [0029] The piping system 106 includes an internal piping 108 and an external piping 110. The internal piping 108 is formed inside the vacuum device 300 and includes an internal supply pipe 112 and an internal return pipe 114. The external pipe 110 is provided outside the vacuum device 300 and includes an external supply pipe 120 and an external return pipe 122. The external piping 110 connects the vacuum device 300 and the plurality of compressor units 102 and 104. [0030] The internal supply line 112 is connected to the air supply port 42 (see FIG. 2) of each cryopump 10, and the internal return line 114 is connected to the exhaust port 44 (see FIG. 2) of each cryopump 10. In addition, the internal supply pipe 112 is connected to one end of the external supply pipe 120 of the external pipe 110 at the air supply port 116 of the vacuum device 300, and the internal return pipe 114 is connected to the external pipe 110 at the exhaust port 118 of the vacuum device 300 One end of the external return pipe 122. [0031] The other end of the external supply line 120 is connected to the first manifold 124, and the other end of the external return line 122 is connected to the second manifold 126. One end of the first discharge pipe 128 of the first compressor unit 102 and the second discharge pipe 130 of the second compressor unit 104 are connected to the first manifold 124. The other ends of the first discharge pipe 128 and the second discharge pipe 130 are respectively connected to the discharge ports 148 of the corresponding compressor units 102 and 104 (see FIG. 3). One end of the first suction pipe 132 of the first compressor unit 102 and the second suction pipe 134 of the second compressor unit 104 are connected to the second manifold 126. The other ends of the first suction pipe 132 and the second suction pipe 134 are respectively connected to suction ports 146 (see FIG. 3) of the corresponding compressor units 102 and 104. [0032] Thereby, a general-purpose supply pipe for collecting and supplying the operating gas sent from each of the compressor units 102 and 104 to the plurality of cryopumps 10 is routed to the internal supply pipe 112 and the outside. The supply line 120 is configured. In addition, a common return pipe for collecting the working gases discharged from the plurality of cryopumps 10 and returning them to the plurality of compressor units 102 and 104 is constituted by an internal return pipe 114 and an external return pipe 122. In addition, each compressor unit of the plurality of compressor units is connected to a common pipeline by a separate pipe attached to each compressor unit. A manifold for connecting the individual pipes to each other is provided at a connection portion between the individual pipes and the common pipe. The first manifold 124 merges individual pipes on the supply side, and the second manifold 126 merges individual pipes on the recovery side. [0033] Depending on the configuration of various devices in the place where the cryopump system 1000 is used (such as a semiconductor manufacturing plant), the above-mentioned common pipeline may also (different from the illustration) become a considerable length. By collecting the operating gas in the common line, the overall piping length can be shortened as compared with a case where each of the plurality of compressors is connected to a vacuum device. In addition, a piping structure in which a plurality of compressors are connected to each supply target of the actuating gas (for example, each of the cryopump 10 in the cryopump system 1000) is redundant, so it also has redundancy. A plurality of compressors are arranged in parallel to each object (for example, a cryopump) and operated, thereby sharing the load on the plurality of compressors. [0034] FIG. 2 is a cross-sectional view schematically showing a cryopump 10 according to an embodiment of the present invention. The cryopump 10 includes a first cryopanel cooled to a first cooling temperature step, and a second cryopanel cooled to a second cooling temperature step lower than the first cooling temperature step. In the first low-temperature plate, the gas having a low vapor pressure in the first cooling temperature step is captured and discharged through condensation. For example, the gas whose vapor pressure is lower than the reference vapor pressure (for example, 10-8Pa) is discharged. In the second low-temperature plate, the gas having a low vapor pressure in the second cooling temperature step is captured and discharged through condensation. An adsorption region is formed on the surface of the second low-temperature plate so as to capture non-condensable gas that does not condense due to the high vapor pressure even in the second temperature step. The adsorption area is formed, for example, by providing an adsorbent on the surface of the plate. The non-condensable gas is adsorbed into the adsorption region cooled to the second temperature stage and discharged. [0035] The cryopump 10 shown in FIG. 2 includes a refrigerator 12, a plate structure 14, and a heat shield 16. The refrigerator 12 generates cold by a heat cycle in which an operating gas is sucked in and expanded to be discharged inside. The plate structure 14 includes a plurality of low-temperature plates, and these plates are cooled by the refrigerator 12. On the surface of the plate, an extremely low-temperature surface for trapping and exhausting the gas by condensing or adsorbing the gas is formed. An adsorbent such as activated carbon for adsorbing a gas is usually provided on the surface (for example, the back surface) of the cryopanel. The heat shield 16 is provided in order to protect the board structure 14 from the surrounding radiant heat. [0036] The cryopump 10 is a so-called vertical cryopump. The vertical-type cryopump means a cryopump which is arranged by inserting the refrigerator 12 in the axial direction of the heat shield 16. The present invention can also be applied to a so-called horizontal cryopump. A horizontal cryopump is a cryopump that is arranged by inserting the second stage cooling stage of the refrigerator in a direction (usually an orthogonal direction) that intersects with the axial direction of the heat shield 16. The horizontal cryopump 10 is schematically shown in FIG. 1. [0037] The refrigerator 12 is a Gifford-McMahon refrigerator (so-called GM refrigerator). The refrigerator 12 is a two-stage refrigerator, and includes a first-stage cylinder 18, a second-stage cylinder 20, a first cooling stage 22, a second cooling stage 24, and a refrigerator motor 26. The first-stage cylinder 18 and the second-stage cylinder 20 are connected in series, and each has a first-stage displacer and a second-stage displacer (not shown) connected to each other. Inside the first-stage displacer and the second-stage displacer, a cold storage material is incorporated. In addition, the freezer 12 may be a freezer other than a 2-stage GM freezer. For example, a single-stage GM freezer may be used. A pulse tube refrigerator or a Solvay refrigerator may also be used. [0038] The freezer 12 includes a flow path switching mechanism that periodically switches the flow path of the working gas in order to periodically suck and discharge the working gas. The flow path switching mechanism includes, for example, a valve portion and a driving portion that drives the valve portion. The valve portion is, for example, a rotary valve, and the drive portion is a motor for rotating the rotary valve. The motor may be, for example, an AC motor or a DC motor. The flow path switching mechanism may be a direct acting type mechanism driven by a linear motor. [0039] A refrigerator motor 26 is provided at one end of the first-stage cylinder 18. The refrigerator motor 26 is provided inside a motor case 27 formed at an end of the first-stage cylinder 18. The refrigerator motor 26 is connected to the first-stage displacer and the second-stage displacer so that the first-stage displacer and the second-stage displacer can reciprocate inside the first-stage cylinder 18 and the second-stage cylinder 20, respectively. Device. In addition, the refrigerator motor 26 is connected to a movable valve (not shown) provided inside the motor casing 27 so as to be able to rotate forward and backward. [0040] The first cooling stage 22 is provided at an end portion on the second-stage cylinder 20 side of the first-stage cylinder 18, that is, a connection portion between the first-stage cylinder 18 and the second-stage cylinder 20. The second cooling stage 24 is provided at the end of the second-stage cylinder 20. The first cooling stage 22 and the second cooling stage 24 are respectively fixed to the first-stage cylinder 18 and the second-stage cylinder 20 by welding, for example. [0041] The refrigerator 12 is connected to the compressor unit 102 or 104 through an air supply port 42 and an exhaust port 44 provided outside the motor casing 27. The connection relationship between the cryopump 10 and the compressor units 102 and 104 is as described with reference to FIG. 1. [0042] The freezer 12 expands the high-pressure operating gas (for example, helium gas) supplied from the compressor units 102 and 104 to generate cold in the first cooling stage 22 and the second cooling stage 24. The compressor units 102 and 104 recover the operating gas expanded by the refrigerator 12 and pressurize it again to supply it to the refrigerator 12. [0043] Specifically, first, high-pressure operating gas is supplied from the compressor units 102 and 104 to the refrigerator 12. At this time, the refrigerator motor 26 drives the movable valve inside the motor housing 27 in a state where the air supply port 42 and the internal space of the refrigerator 12 are communicated. When the internal space of the refrigerator 12 is filled with the high-pressure operating gas, the movable valve is switched by the refrigerator motor 26, and the internal space of the refrigerator 12 communicates with the exhaust port 44. Thereby, the operating gas is expanded and recovered to the compressor units 102 and 104. In synchronization with the operation of the movable valve, the first-stage displacer and the second-stage displacer reciprocate inside the first-stage cylinder 18 and the second-stage cylinder 20, respectively. By performing such a heat cycle repeatedly, the refrigerator 12 causes the first cooling stage 22 and the second cooling stage 24 to cold. [0044] The second cooling stage 24 cools to a lower temperature than the first cooling stage 22. The second cooling stage 24 is cooled to, for example, about 10K to 20K, and the first cooling stage 22 is cooled to, for example, about 80K to 100K. A first temperature sensor 23 for measuring the temperature of the first cooling stage 22 is mounted on the first cooling stage 22, and a second temperature sensor for measuring the temperature of the second cooling stage 24 is mounted on the second cooling stage 24. 25. [0045] On the first cooling stage 22 of the refrigerator 12, the heat shield 16 is fixed in a thermally connected state, and on the second cooling stage 24 of the refrigerator 12, the plate structure 14 is fixed in a thermally connected state. . Therefore, the heat shield 16 is cooled to the same temperature as the first cooling stage 22, and the plate structure 14 is cooled to the same temperature as the second cooling stage 24. The heat shield 16 is formed in a cylindrical shape having an opening 31 at one end. The opening portion 31 is partitioned by the inner surface of the end portion of the cylindrical side surface of the heat shield 16. [0046] On the other hand, a blocking portion 28 is formed on the opposite side of the opening portion 31 of the heat shield 16, that is, on the other end of the pump bottom side. The closing portion 28 is formed by a flange portion extending radially inward at an end portion on the pump bottom side of the cylindrical side surface of the heat shield 16. Since the cryopump 10 shown in FIG. 2 is a vertical cryopump, the flange portion is attached to the first cooling stage 22 of the refrigerator 12. As a result, a cylindrical inner space 30 is formed inside the heat shield 16. The refrigerator 12 protrudes along the center axis of the heat shield 16 toward the internal space 30, and the second cooling stage 24 is inserted into the internal space 30. [0047] In the case of a horizontal cryopump, the occlusion portion 28 is usually completely occluded. The freezer 12 is protruded toward the internal space 30 from a freezer attachment opening formed in a side surface of the heat shield 16 in a direction orthogonal to the central axis of the heat shield 16. The first cooling stage 22 of the refrigerator 12 is attached to the refrigerator installation opening of the heat shield 16, and the second cooling stage 24 of the refrigerator 12 is disposed in the internal space 30. A plate structure 14 is attached to the second cooling stage 24. Accordingly, the plate structure 14 is disposed in the inner space 30 of the heat shield 16. The plate structure 14 can be mounted on the second cooling stage 24 via a plate mounting member having an appropriate shape. [0048] A blocking body 32 is attached to the opening 31 of the heat shield 16. The blocking body 32 is provided at a distance from the plate structure 14 in the central axis direction of the heat shield 16. The blocking body 32 is attached to an end portion on the opening 31 side of the heat shield 16 and is cooled to the same temperature as the heat shield 16. When viewed from the vacuum chamber 80 side, the blocking body 32 may be formed in, for example, a concentric circle shape, or may be formed in another shape such as a lattice shape. A gate valve (not shown) is provided between the blocking body 32 and the vacuum chamber 80. This gate valve is closed, for example, when the cryopump 10 is operated, and is opened when the vacuum chamber 80 is exhausted by the cryopump 10. The vacuum chamber 80 is provided in, for example, the vacuum device 300 shown in FIG. 1. [0049] The heat shield 16, the blocking body 32, the plate structure 14, and the first cooling stage 22 and the second cooling stage 24 of the refrigerator 12 are housed inside the pump casing 34. The pump casing 34 is formed by connecting two cylinders having different diameters in series. The large-diameter cylindrical side end portion of the open pump casing 34 is formed by extending the flange portion 36 for connection with the vacuum chamber 80 to the outside in the radial direction. The small-diameter cylindrical-side end of the pump casing 34 is fixed to the motor housing 27 of the refrigerator 12. The cryopump 10 is air-tightly fixed to the exhaust opening of the vacuum chamber 80 via the flange portion 36 of the pump casing 34, and forms an air-tight space integrated with the internal space of the vacuum chamber 80. Both the pump casing 34 and the heat shield 16 are formed in a cylindrical shape, and are disposed on the same axis. Since the inner diameter of the pump casing 34 is slightly larger than the outer diameter of the heat shield 16, the heat shield 16 and the inner surface of the pump casing 34 are arranged with a certain interval therebetween. [0050] When the cryopump 10 is operated, first, before the operation of the cryopump 10, the inside of the vacuum chamber 80 is roughly pumped to about 1 Pa to 10 Pa by using another appropriate rough pump. Thereafter, the cryopump 10 is operated. The first cooling stage 22 and the second cooling stage 24 are cooled by the drive of the refrigerator 12, and the heat shield 16, the blocking body 32, and the plate structure 14 which are connected to these heat are also cooled. [0051] The cooled barrier body 32 cools the gas molecules flying from the vacuum chamber 80 to the inside of the cryopump 10, and condenses a gas (for example, moisture) having a sufficiently low vapor pressure at the cooling temperature on the surface And drained. After the gas whose vapor pressure has not sufficiently decreased at the cooling temperature of the barrier body 32 passes through the barrier body 32, it enters the inside of the heat shield 16. Among the gas molecules that have entered, a gas (for example, argon) having a sufficiently low vapor pressure at the cooling temperature of the plate structure 14 is condensed on the surface of the plate structure 14 and discharged. At this cooling temperature, a gas (for example, hydrogen gas) that does not sufficiently decrease the vapor pressure is adsorbed and discharged by an adsorbent adhering to the surface of the plate structure 14 and cooling. Thereby, the cryopump 10 can make the degree of vacuum inside the vacuum chamber 80 reach a desired level. 3 is a diagram schematically showing a first compressor unit 102 according to an embodiment of the present invention. The second compressor unit 104 also has the same configuration as the first compressor unit 102 in this embodiment. The compressor unit 102 includes a compressor main body 140 for boosting gas, a low-pressure piping 142 for supplying low-pressure gas supplied from the outside to the compressor main body 140, and a high pressure for compressing the compressor main body 140. It is constituted by a high-pressure pipe 144 through which gas is sent to the outside. [0053] As shown in FIG. 1, the low-pressure gas is supplied to the first compressor unit 102 through the first suction pipe 132. The first compressor unit 102 receives the return gas from the cryopump 10 through the suction port 146, and the operating gas is sent to the low-pressure pipe 142. The suction port 146 is provided at the end of the low-pressure pipe 142 and is in the compressor housing 138 of the first compressor unit 102. The low-pressure pipe 142 connects the suction port 146 and the suction port of the compressor body 140. [0054] The low-pressure pipe 142 is provided with a reservoir 150 as a volume for removing pulsation included in the return gas in the middle. The storage tank 150 is provided between the suction port 146 and a branch toward a bypass mechanism 152 described later. The pulsating operating gas is removed from the storage tank 150 and is supplied to the compressor main body 140 through a low-pressure pipe 142. A filter for removing unnecessary particles or the like from the gas may be provided inside the storage tank 150. Between the storage tank 150 and the suction port 146, a receiving port and a piping for supplementing an operating gas from the outside may be connected. [0055] The compressor main body 140 is, for example, a scroll-type or rotary-type pump, and has a function of increasing the pressure of the sucked gas. The compressor main body 140 is provided with a compressor motor 172, and the compressor main body 140 is driven by the compressor motor 172. The compressor main body 140 sends the boosted working gas to the high-pressure pipe 144. The compressor main body 140 is configured to use oil for cooling, and an oil cooling pipe for circulating oil is provided in the compressor main body 140 in addition. Therefore, the boosted operating gas is sent to the high-pressure pipe 144 in a state where some of the oil is mixed. [0056] Therefore, an oil separator 154 is provided in the middle of the high-pressure pipe 144. The oil separated from the operating gas by the oil separator 154 is returned to the low-pressure pipe 142, and may be returned to the compressor main body 140 by the low-pressure pipe 142. The oil separator 154 may be provided with a release valve for releasing an excessively high pressure. [0057] In the middle of the high-pressure pipe 144 connecting the compressor main body 140 and the oil separator 154, a heat exchanger (not shown) for cooling the high-pressure operating gas sent from the compressor main body 140 may be provided. The heat exchanger cools the working gas, for example, with cooling water. The cooling water can also be used as oil for cooling the compressor body 140 for cooling. The high-pressure pipe 144 may be provided with a temperature sensor that measures the temperature of the working gas in at least one of the upstream and downstream of the heat exchanger. [0058] The gas that has been moved by the oil separator 154 is sent to the adsorber 156 through the high-pressure pipe 144. The adsorber 156 is provided, for example, to remove contaminated components that have not been removed by a pollutant removal mechanism on a flow path such as a filter in the storage tank 150 or an oil separator 154 from the working gas. The adsorber 156 removes the vaporized oil component by, for example, adsorption. [0059] The discharge port 148 is provided at the end of the high-pressure pipe 144, and is located in the compressor housing 138 of the first compressor unit 102. That is, the high-pressure pipe 144 connects the compressor main body 140 and the discharge port 148, and an oil separator 154 and an adsorber 156 are provided in the middle. The operating gas passing through the adsorber 156 is sent to the cryopump 10 through the discharge port 148. [0060] The first compressor unit 102 includes a bypass mechanism 152 that includes a bypass pipe 158 that connects the low-pressure pipe 142 and the high-pressure pipe 144. In the illustrated embodiment, the bypass pipe 158 is branched from the low-pressure pipe 142 between the storage tank 150 and the compressor body 140. The bypass pipe 158 is branched from the high-pressure pipe 144 between the oil separator 154 and the adsorber 156. [0061] The bypass mechanism 152 is provided with a control valve for controlling the flow rate of the operating gas that is bypassed from the high-pressure pipe 144 to the low-pressure pipe 142 without being sent to the cryopump 10. In the illustrated embodiment, a first control valve (also referred to as a pressure equalizing valve) 160 and a second control valve (also referred to as a release valve) 162 are provided in parallel in the middle of the bypass pipe 158. The pressure equalizing valve 160 is, for example, a normally open solenoid valve. Thereby, when the operation of the first compressor unit 102 is stopped (that is, when the power supply to the first compressor unit 102 is stopped), the pressure equalizing valve 160 is opened, and the pressures of the low-pressure pipe 142 and the high-pressure pipe 144 become equal. The release valve 162 is, for example, a normally closed solenoid valve. In this embodiment, the release valve 162 is used as a flow control valve of the bypass pipe 158 during the operation of the first compressor unit 102. [0062] The first compressor unit 102 includes a first pressure sensor 164 for measuring the pressure of the return gas from the cryopump 10, and a second pressure sensor for measuring the pressure of the gas sent from the cryopump 10测 器 166。 166. In the operation of the first compressor unit 102, the sent gas is higher in pressure than the returned gas. Therefore, the first pressure sensor 164 and the second pressure sensor 166 are also referred to as a low pressure sensor and a high pressure sensor, respectively. Device. [0063] The first pressure sensor 164 is provided to measure the pressure of the low-pressure pipe 142, and the second pressure sensor 166 is provided to measure the pressure of the high-pressure pipe 144. The first pressure sensor 164 is provided, for example, in the storage tank 150, and measures the pressure of the return gas from which the pulsation is removed in the storage tank 150. The first pressure sensor 164 may be installed at any position of the low-pressure pipe 142. The second pressure sensor 166 is provided between the oil separator 154 and the adsorber 156. The second pressure sensor 166 may be installed at any position of the high-pressure pipe 144. [0064] The first pressure sensor 164 and the second pressure sensor 166 may be provided outside the first compressor unit 102. For example, the first pressure sensor 164 and the second pressure sensor 166 may be provided on the first suction pipe 132 and the first discharge pipe 128, for example. In addition, the bypass mechanism 152 may be provided outside the first compressor unit 102. For example, the first suction pipe 132 and the first discharge pipe 128 may be connected by a bypass pipe 158. [0065] The compressor structure section 136 shown in FIG. 3 includes a compressor body 140, a low-pressure pipe 142, a high-pressure pipe 144, a suction port 146, a discharge port 148, a storage tank 150, a bypass mechanism 152, and an oil separator 154. , An adsorber 156, a bypass pipe 158, a pressure equalizing valve 160, a release valve 162, a first pressure sensor 164, a second pressure sensor 166, and a compressor motor 172. These components are housed in the compressor housing 138. [0066] FIG. 4 is a control block diagram related to the cryopump system 1000 of this embodiment. FIG. 4 shows a main part of a cryopump system 1000 according to an embodiment of the present invention. The internal details of one of the plurality of cryopumps 10 are shown, and the other cryopumps 10 are not shown for the same reason. Similarly, the first compressor unit 102 is shown in detail, and the second compressor unit 104 is the same as the second compressor unit 104. Therefore, the internal illustration is omitted. [0067] As described above, the CP controller 100 is connected to the IO module 50 of each cryopump 10 so as to be communicable. The IO module 50 includes a refrigerator inverter 52 and a signal processing unit 54. The refrigerator inverter 52 adjusts power of a predetermined voltage and frequency supplied from an external power source, such as a commercial power source, and supplies it to the refrigerator motor 26. The voltage and frequency to be supplied to the refrigerator motor 26 are controlled by the CP controller 100. [0068] The CP controller 100 determines the command control amount according to the sensor output signal. The signal processing unit 54 relays the command control amount sent from the CP controller 100 to the refrigerator inverter 52. For example, the signal processing unit 54 converts a command signal from the CP controller 100 into a signal that can be processed by the refrigerator inverter 52 and sends the signal to the refrigerator inverter 52. The command signal includes a signal indicating the operating frequency of the refrigerator motor 26. The signal processing unit 54 relays the outputs of various sensors of the cryopump 10 to the CP controller 100. For example, the signal processing unit 54 converts the sensor output signal into a signal that can be processed by the CP controller 100 and sends it to the CP controller 100. [0069] Various sensors including a first temperature sensor 23 and a second temperature sensor 25 are connected to the signal processing unit 54 of the IO module 50. As described above, the first temperature sensor 23 measures the temperature of the first cooling stage 22 of the refrigerator 12, and the second temperature sensor 25 measures the temperature of the second cooling stage 24 of the refrigerator 12. The first temperature sensor 23 and the second temperature sensor 25 periodically measure the temperatures of the first cooling stage 22 and the second cooling stage 24, respectively, and output signals indicating the measured temperatures. The measured values of the first temperature sensor 23 and the second temperature sensor 25 are input to the CP controller 100 every predetermined time, and are stored and held in a predetermined memory area of the CP controller 100. [0070] The CP controller 100 controls the refrigerator 12 in accordance with the temperature of the cryopanel. The CP controller 100 gives a command signal to the refrigerator 12 so that the actual temperature of the cryopanel follows the target temperature. For example, the CP controller 100 generates a refrigerating machine inverter command signal through feedback control so as to minimize the deviation between the target temperature of the first-stage low-temperature board and the measurement temperature of the first temperature sensor 23. The refrigerator inverter instruction signal is given from the CP controller 100 to the refrigerator inverter 52 via the IO module 50. The freezer inverter 52 controls the operating frequency of the freezer motor 26 in accordance with the freezer inverter command signal. The rotation speed of the refrigerator motor 26, that is, the frequency of the thermal cycle of the refrigerator 12, is determined according to the operating frequency of the refrigerator motor 26. The target temperature of the first-stage cryopanel is set to a specification based on a procedure performed in the vacuum chamber 80, for example. In this case, the second cooling stage 24 and the plate structure 14 of the refrigerator 12 are cooled to a temperature determined in accordance with the specifications of the refrigerator 12 and a heat load from the outside. [0071] When the measured temperature of the first temperature sensor 23 is higher than the target temperature, the CP controller 100 outputs a refrigerator inverter instruction signal to the IO module 50 in order to increase the operating frequency of the refrigerator motor 26. . In conjunction with an increase in the motor operating frequency, the frequency of the thermal cycle in the refrigerator 12 also increases, and the first cooling stage 22 of the refrigerator 12 is cooled toward the target temperature. Conversely, when the measurement temperature of the first temperature sensor 23 is lower than the target temperature, the operating frequency of the refrigerator motor 26 decreases, and the first cooling stage 22 of the refrigerator 12 is heated toward the target temperature. [0072] Normally, the target temperature of the first cooling stage 22 is set to a fixed value. Thus, when the thermal load on the cryopump 10 is increased, the CP controller 100 outputs a refrigerating machine inverter command signal to increase the operating frequency of the refrigerator motor 26. When the thermal load on the cryopump 10 is reduced, the refrigerating machine frequency is output The freezer command signal reduces the operating frequency of the refrigerator motor 26. In addition, the target temperature may be appropriately changed. For example, the target temperature of the cryopanel may be sequentially set so that the target ambient pressure is achieved in the exhaust target volume. In addition, the CP controller 100 may also control the operating frequency of the refrigerator motor 26 so that the actual temperature of the second-stage cryopanel is consistent with the target temperature. [0073] In a typical cryopump, the frequency of the thermal cycle is always set constant. It is set to operate at a large frequency so that the pump can be rapidly cooled from normal temperature to the operating temperature of the pump. When the heat load from the outside is small, the heater is used to adjust the temperature of the cryopanel. Therefore, power consumption becomes large. In contrast, in this embodiment, since the thermal cycle frequency is controlled in accordance with the thermal load of the cryopump 10, a cryopump excellent in energy saving can be realized. In addition, a heater is not necessarily provided, which also contributes to reduction in power consumption. [0074] The CP controller 100 is connected to the compressor controller 168 so as to be communicable. The control unit of the cryopump system 1000 according to an embodiment of the present invention is configured by a plurality of controllers including a CP controller 100 and a compressor controller 168. In another embodiment, the control unit of the cryopump system 1000 may be constituted by a single CP controller 100, and the compressor units 102 and 104 may be provided with an IO module instead of the compressor controller 168. In this case, the IO module relays control signals between the CP controller 100 and the constituent elements of the compressor units 102 and 104. And, the compressor controller 168 may constitute a part of the CP controller 100. [0075] The compressor controller 168 controls the first compressor unit 102 according to a control signal from the CP controller 100 or independently of the CP controller 100. In one embodiment, the compressor controller 168 receives signals indicating various set values from the CP controller 100 and uses the set values to control the first compressor unit 102. The compressor controller 168 determines the command control amount according to the sensor output signal. Like the CP controller 100, the compressor controller 168 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for storing data or executing programs, an input / output interface, And memory devices. [0076] The compressor controller 168 sends a signal indicating the operation state of the first compressor unit 102 to the CP controller 100. The signal indicating the operation state includes, for example, measured pressures of the first pressure sensor 164 and the second pressure sensor 166, the opening degree or control current of the release valve 162, and the operating frequency of the compressor motor 172. [0077] The first compressor unit 102 includes a compressor inverter 170 and a compressor motor 172. The compressor motor 172 is a motor that operates the compressor main body 140 with a variable operating frequency, and is provided in the compressor main body 140. As the refrigerator motor 26, as the compressor motor 172, various motors can be used. The compressor controller 168 generates a compressor inverter command signal and outputs it to the compressor inverter 170. The compressor inverter 170 controls the operating frequency of the compressor motor 172 according to a compressor inverter command signal. The rotation speed of the compressor motor 53 is controlled in accordance with the operating frequency of the compressor motor 172. The compressor inverter 170 adjusts electric power of a predetermined voltage and frequency supplied from an external power source such as a commercial power source in accordance with a compressor inverter command signal, and supplies the electric power to the compressor motor 172. The voltage and frequency to be supplied to the compressor motor 172 are determined according to the compressor inverter command signal. [0078] Various sensors including a first pressure sensor 164 and a second pressure sensor 166 are connected to the compressor controller 168. As described above, the first pressure sensor 164 periodically measures the pressure on the suction side of the compressor body 140, and the second pressure sensor 166 periodically measures the pressure on the discharge side of the compressor body 140. The measured values of the first pressure sensor 164 and the second pressure sensor 166 are input to the compressor controller 168 every predetermined time, and are stored and held in a predetermined memory area of the compressor controller 168. [0079] The above-mentioned release valve 162 is connected to the compressor controller 168. A release valve driver 174 for driving the release valve 162 is attached to the release valve 162. The release valve driver 174 is connected to the compressor controller 168. The compressor controller 168 generates a release valve command signal and outputs it to the release valve driver 174. The release valve command signal is for determining the opening degree of the release valve 162, and the release valve driver 174 controls the release valve 162 at the opening degree. After this, the release valve 162 is installed in the bypass pipe 158 and controls the flow of the bypass pipe 158 according to the release valve command signal. The release valve driver 174 may be assembled to the compressor controller 168. [0080] The compressor controller 168 controls the compressor main body 140 so that a differential pressure (hereinafter, sometimes referred to as a compressor differential pressure) between the input and output ports of the compressor unit 102 is maintained at a target differential pressure. For example, the compressor controller 168 performs feedback control so that the differential pressure between the input and output ports of the compressor unit 102 is set to a constant value. In one embodiment, the compressor controller 168 obtains the differential pressure of the compressor from the measured values of the first pressure sensor 164 and the second pressure sensor 166. The compressor controller 168 determines the operating frequency of the compressor motor 172 so that the compressor differential pressure is consistent with the target value. The compressor controller 168 controls the compressor inverter 170 to achieve the aforementioned operating frequency. In addition, the target value of the differential pressure can be changed while performing the differential pressure constant control. [0081] With such constant differential pressure control, further reduction in power consumption can be achieved. When the heat load to the cryopump 10 and the refrigerator 12 is small, the thermal cycle frequency in the refrigerator 12 is reduced by the above-mentioned cryogenic plate temperature adjustment control. Thereby, the amount of operating gas required in the refrigerator 12 becomes small. At this time, an amount of gas exceeding the required amount can be sent from the compressor unit 102. This increases the differential pressure between the input and output ports of the compressor unit 102. However, in this embodiment, the operating frequency of the compressor motor 172 is controlled so that the differential pressure of the compressor is constant. In this case, the operating frequency of the compressor motor 172 is reduced so that the differential pressure decreases toward the target value. Therefore, like a typical cryopump, power consumption can be reduced compared to a case where the compressor is always operated at a constant operating frequency. [0082] On the other hand, when the thermal load on the cryopump 10 becomes large, the operating frequency of the compressor motor 172 is increased so that the differential pressure of the compressor becomes constant. Therefore, since the amount of gas supplied to the refrigerator 12 can be sufficiently ensured, it is possible to suppress the deviation of the low-temperature plate temperature from the target temperature due to an increase in the heat load to a minimum. [0083] In particular, when the timing of opening the valve on the high-pressure side for inhaling the operating gas overlaps or is extremely close to the plurality of refrigerators 12, the total amount of required gas becomes large. For example, when the compressor is operated only at a constant discharge flow rate, or when the discharge pressure of the compressor is insufficient, compared with a refrigerator in which the valve is opened first and the air is sucked in, The amount of gas supplied is reduced. The difference in the amount of supplied gas between the plurality of refrigerators 12 causes a deviation in the refrigerating capacity between the refrigerators 12. Compared with such a case, it is possible to sufficiently ensure the operating gas flow rate to the refrigerator 12 by performing differential pressure control. The differential pressure control not only contributes to energy saving performance, but also suppresses variations in the refrigeration capacity between the plurality of refrigerators 12. 5 is a diagram for explaining a control flow of operation control of a compressor unit according to an embodiment of the present invention. The control process shown in FIG. 5 is repeatedly executed at a predetermined cycle through the compressor controller 168 during the operation of the cryopump 10. This processing is performed in the compressor controller 168 of each compressor unit 102 and 104 independently from the other compressor units 102 and 104. In FIG. 5, the operation processing part of the compressor controller 168 is separated by a broken line, and the operation movement of the hardware of the compressor units 102 and 104 is separated by a single-dot chain line. [0085] The compressor controller 168 includes a control amount calculation unit 176. The control amount calculation unit 176 is configured to calculate, for example, a command control amount used for at least the differential pressure constant control. In this embodiment, the calculated command control amount is distributed to the operating frequency of the compressor motor 172 and the opening degree of the release valve 162 to perform constant differential pressure control. In another embodiment, the differential pressure constant control may be performed using only one of the operating frequency of the compressor motor 172 and the opening degree of the release valve 162 as a command control amount. The control amount calculation unit 176 may be configured to calculate a command control amount used for at least any one of the control of the differential pressure constant control, the discharge pressure control, and the control of the suction pressure, as described later. [0086] As shown in FIG. 5, the compressor controller 168 has a target differential pressure ΔP ₀ set and input in advance. The target differential pressure is set, for example, in the CP controller 100 and is given to the compressor controller 168. The measurement pressure PL on the suction side is measured by the first pressure sensor 164, and the measurement pressure PH on the discharge side is measured by the second pressure sensor 166, and is supplied to the compressor controller 168 from each sensor. Generally, the measurement pressure PL of the first pressure sensor 164 is lower than the measurement pressure PH of the second pressure sensor 166. [0087] The compressor controller 168 includes a deviation calculation unit 178 that subtracts the suction-side measurement pressure PL from the discharge-side measurement pressure PH to obtain the measurement differential pressure ΔP, and further subtracts the measurement from the set differential pressure ΔP _0. The differential pressure ΔP is used to determine the differential pressure deviation e. The control amount calculation unit 176 of the compressor controller 168 calculates the commanded control amount D from the differential pressure deviation e, for example, by a predetermined control amount calculation process including a PD calculation or a PID calculation. [0088] As shown in the figure, the compressor controller 168 may include a deviation calculation unit 178 in addition to the control amount calculation unit 176, and the control amount calculation unit 176 may include a deviation calculation unit 178. In addition, an integral calculation unit for multiplying the command control quantity D for a predetermined time and providing it to the output allocation processing unit 180 may be provided at a subsequent stage of the control quantity calculation unit 176. [0089] The compressor controller 168 includes an output allocation processing unit 180 that allocates the command control amount D to the first command output value D1 and the second command output value D2. The output allocation processing unit 180 determines the first command output value D1 and the second command output value D2 in accordance with the magnitude of the command control amount D value. The output allocation processing unit 180 refers to the output allocation table 181, and thereby determines the first command output value D1 and the second command output value D2 from the command control amount D. The output distribution table 181 is prepared in advance and stored in the output distribution processing unit 180 or the compressor controller 168. [0090] The command control amount D is a parameter corresponding to the target flow rate of the compressor unit. The command control amount D indicates an operating gas flow rate that the compressor unit should send in order to achieve a target pressure such as the target differential pressure ΔP ₀ . In addition, the command control amount D need not directly indicate the target flow rate of the compressor unit itself. The command control amount D can be a parameter related to the target flow rate of the compressor unit or any parameter related to the target flow rate of the compressor unit according to a function or a table. [0091] The first command output value D1 is a parameter corresponding to the command value of the operating frequency of the compressor motor 172. The first command output value D1 may be a parameter related to the operation frequency command value according to a function or a table, or an arbitrary parameter related to the operation frequency command value. The second command output value D2 is a parameter corresponding to the opening degree command value of the release valve 162. The second command output value D2 may be a parameter related to the opening degree command value according to a function or table, or any parameter related to the opening degree command value. [0092] The compressor controller 168 includes an inverter instruction unit 182 that generates a compressor inverter instruction signal E from the first output instruction value D1, and a release valve instruction that generates a release valve instruction signal R from the second output instruction value D2.部 184. The compressor inverter instruction signal E is given to the compressor inverter 170, and the operating frequency of the compressor body 140, that is, the compressor motor 172 is controlled in accordance with the instruction. The compressor inverter command signal E is a voltage signal or other electric signal indicating, for example, a command value of the operating frequency. The release valve command signal R is given to the release valve driver 174, and the opening degree of the release valve 162 is controlled in accordance with the instruction. The release valve command signal R is an electric signal indicating an opening degree command value of the release valve 162, and is, for example, a pulse output signal for driving a solenoid coil. [0093] With this, the compressor controller 168 decides to release the valve command signal R and the compressor inverter command signal E, so that the actuating gas is supplied from the compressor units 102, 104 to the cryopump 10 (ie, refrigeration Machine 12). The compressor controller 168 controls the opening degree of the release valve 162 according to the determined release valve command signal R. The compressor controller 168 outputs the release valve command signal R to the release valve driver 174, thereby opening the release valve 162 according to the release valve command signal R. The compressor controller 168 controls the operating frequency of the compressor main body 140 in accordance with the determined compressor inverter command signal E. The compressor controller 168 outputs the compressor inverter command signal E to the compressor inverter 170, thereby controlling the operating frequency of the compressor motor 172 in accordance with the compressor inverter command signal E. [0094] The pressure of the helium gas as the actuating gas is determined according to the operating states of the compressor main body 140 and the release valve 162, and the characteristics of the related piping or tank. The helium pressure thus determined is measured by the first pressure sensor 164 and the second pressure sensor 166. [0095] As described above, in each of the compressor units 102 and 104, each of the compressor controllers 168 independently performs a constant differential pressure control. The compressor controller 168 performs feedback control so that the differential pressure deviation e is minimized (it is better to be zero). [0096] However, the deviation e shown in FIG. 5 is not limited to the deviation of the differential pressure. In one embodiment, the compressor controller 168 may perform a discharge pressure control that calculates a commanded control amount from a deviation between the discharge side measured pressure PH and a set pressure. In this case, the set pressure may be an upper limit value of the discharge-side pressure of the compressor. When the discharge-side measured pressure PH is greater than the upper limit, the compressor controller 168 may calculate a commanded control amount from a deviation from the discharge-side measured pressure PH. The upper limit value can be set empirically or experimentally, for example, in accordance with the maximum discharge pressure of the compressor that guarantees the exhaust capacity of the cryopump 10. [0097] With this, it is possible to suppress an excessive increase in the discharge pressure and further improve safety. Therefore, the discharge pressure control is an example of protection control for a compressor unit. [0098] Furthermore, in one embodiment, the compressor controller 168 may perform a suction pressure control that calculates a command control amount from a deviation between the measured pressure PL and the set pressure on the suction side. In this case, the set pressure may be a lower limit value of the pressure on the suction side of the compressor. When the suction-side measured pressure PL is less than the lower limit, the compressor controller 168 may calculate a commanded control amount based on a deviation from the suction-side measured pressure PL. The lower limit value can be set empirically or experimentally, for example, in accordance with the minimum suction pressure of the compressor that guarantees the exhaust capacity of the cryopump 10. [0099] Accordingly, it is possible to suppress an excessive temperature rise of the compressor main body caused by a decrease in the flow rate of the operating gas due to a decrease in the suction pressure. In addition, when a gas leak occurs from the piping system of the actuating gas, it is not necessary to stop the operation immediately, and it is possible to prevent an excessive pressure drop and continue the operation for a certain period of time. Therefore, the control of the suction pressure is an example of the protection control for the compressor unit. 6 is a diagram schematically illustrating an output allocation table 181 according to an embodiment of the present invention. The vertical axis indicates the first output command value D1 (solid line) and the second output command value D2 (dashed line), and the horizontal axis indicates the command control amount D. The first output command value D1 is indicated by a solid line, and the second output command value D2 is indicated by a dashed line. As described above, the first output command value D1 and the second output command value D2 are respectively equivalent to or related to the operating frequency command value and the opening degree command value, and the command control amount D is equivalent to or related to the target flow rate of the compressor unit. Thereby, the output distribution table 181 shows the relationship between the operating frequency command value of the compressor motor 172 and the target flow rate of the compressor unit, and the relationship between the opening degree command value of the release valve 162 and the target flow rate of the compressor unit. [0101] The range of possible values of the first output command value D1 is limited in advance to the first interval and the second interval. The first interval is a range from the lower limit value D1L to the first value D11, and the second interval is a range from the second value D12 to the upper limit value D1U. The first output command value D1 is related to the operating frequency command value, so the lower limit value D1L, the first value D11, the second value D12, and the upper limit value D1U shown in the figure correspond to the lower limit value and the first value of the operating frequency, respectively. , The second value and the upper limit. [0102] According to this, according to the output allocation table 181, the range of values that can be adopted for the operating frequency is limited in advance to the first operating frequency interval from the lower limit value to the first value, and the range from the second value to the upper limit value. The second operating frequency range. The lower limit of the operating frequency is greater than zero, for example between 20 Hz and 40 Hz, or between 25 Hz and 35 Hz, for example 30 Hz. The upper limit value of the operating frequency may be, for example, from 70 Hz to 90 Hz, or from 75 Hz to 85 Hz, and may be, for example, 78 Hz. The upper limit value and the lower limit value of the operating frequency are determined in advance as specifications of the compressor, for example. [0103] The section from the first value D11 to the second value D12 is not used. The unused frequency range from the first value to the second value of the operating frequency corresponding to the section is determined to include at least a part of the compressor structure portion 136 (for example, the low-pressure pipe 142, the high-pressure pipe 144, the bypass pipe 158, etc.) Piping) at least one natural frequency ω0. The first and second values of the operating frequency are between the lower limit and the upper limit, and the second value is greater than the first value. The natural frequency ω0 is known based on the designer's empirical insights, experiments, or simulations. The first value is determined to be smaller than the natural frequency ω0, and the second value is determined to be larger than the natural frequency ω0. [0104] In the output allocation table 181, the first value d1, the second value d2, the third value d3, and the fourth value d4 of the command control amount D, and the lower limit values D1L and the first value of the first output command value D1 D11, the second value D12, and the upper limit value D1U are associated with each other. In this way, the set of the designated command control amount D and the first output command value D1 (that is, (d1, D1L), (d2, D11), (d3, D12), (d4, D1U)) are mutually Linear interpolation is determined as the relationship between the command control amount D and the first output command value D1. [0105] As shown in FIG. 6, when the command control amount D is between the minimum value d0 and the first value d1, the first output command value D1 takes a lower limit value D1L. When the command control amount D is between the first value d1 and the second value d2, the first output command value D1 is between the lower limit value D1L and the first value D11, and the first output command value D1 and the command control amount D are between There is a linear or proportional relationship between them. When the command control amount D is between the second value d2 and the third value d3, the first output command value D1 takes the second value D12. When the command control amount D is between the third value d3 and the fourth value d4, the first output command value D1 is between the second value D12 and the upper limit value D1U, and the first output command value D1 and the command control amount D There is a linear or proportional relationship between them. [0106] According to the relationship between the command control amount D and the first output command value D1, in the output allocation table 181, the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge flow rate of the compressor main body 140, and The lower limit value, the first value, the second value, and the upper limit value of the operating frequency are associated with each other. When the target flow rate of the compressor unit is smaller than the lower limit discharge flow rate, the operating frequency is fixed at the lower limit value. When the target flow rate increases from the lower limit discharge flow rate to the first discharge flow rate, the operating frequency linearly increases from the lower limit value to the first value. When the target flow rate reaches the first discharge flow rate, the operating frequency is switched from the first value to the second value, and does not increase continuously. When the target flow rate increases from the first discharge flow rate to the second discharge flow rate, the operating frequency is fixed at the second value. When the target flow rate increases from the second discharge flow rate to the upper limit value, the operating frequency linearly increases from the second value to the upper limit value. When the target flow rate decreases, the operating frequency changes in the opposite manner. [0107] In the output allocation table 181, the minimum value d0, the first value d1, the second value d2, the third value d3, and the fourth value d4 of the command control amount D and the maximum value of the second output command value D2 D22, minimum value D20, intermediate value D21, minimum value D20, minimum value D20 are correspondingly associated. The maximum value D22 of the second output command value D2 may correspond to the maximum opening degree of the release valve 162. The minimum value D20 of the second output command value D2 may correspond to the closing of the release valve 162. The intermediate value D21 of the second output command value D2 may correspond to a certain intermediate opening degree of the release valve 162. The group of the command control amount D and the second output command value D2 is determined by the linear interpolation as the relationship between the command control amount D and the second output command value D2. [0108] As shown in FIG. 6, when the command control amount D is between the minimum value d0 and the first value d1, the second output command value D2 is between the maximum value D22 and the minimum value D20, and the second output command value is There is a linear or proportional relationship between D2 and the command control amount D. When the command control amount D is between the first value d1 and the second value d2, the second output command value D2 takes the minimum value D20. When the command control amount D is between the second value d2 and the third value d3, the second output command value D2 is between the intermediate value D21 and the minimum value D20, and between the second output command value D2 and the command control amount D There is a linear or proportional relationship. When the command control amount D is between the third value d3 and the fourth value d4, the second output command value D2 takes the minimum value D20. [0109] According to the relationship between the command control amount D and the second output command value D2, in the output distribution table 181, the discharge flow rate of the compressor main body 140 and the opening degree of the release valve 162 (that is, the flow rate of the bypass pipe 158) ) Correspondence. When the target flow rate of the compressor unit is zero, the release valve 162 is set to the maximum opening degree. When the target flow rate increases from zero to the lower limit, the opening degree of the release valve 162 gradually decreases. When the target flow rate increases from the lower limit discharge flow rate to the first discharge flow rate, the release valve 162 is closed. When the target flow rate reaches the first discharge flow rate, the release valve 162 is opened at an intermediate opening degree. When the target flow rate increases from the first discharge flow rate to the second discharge flow rate, the opening degree of the release valve 162 gradually decreases. When the target flow rate increases from the second discharge flow rate to the upper limit value, the release valve 162 is closed. When the target flow decreases, the opening degree changes in the opposite form. [0110] By referring to such an output distribution table 181, when the target flow rate is between the first discharge flow rate and the second discharge flow rate, the compressor controller 168 takes the second value at the operating frequency to determine the inverter command Signal E. At the same time, the compressor controller 168 decides to release the valve command signal R so that the flow rate of the bypass pipe 158 is consistent with the differential flow rate minus the target flow rate from the discharge flow rate of the compressor main body 140 obtained according to the aforementioned inverter command signal. [0111] According to the compressor unit of the embodiment, the non-use interval of the operating frequency is determined so as to include the natural frequency ω0 of the compressor structure portion 136. Therefore, resonance of the compressor structure portion 136 based on the operation of the compressor body 140 is unlikely to occur. . In addition, since the inverter command signal E is determined by taking the second value of the operating frequency, the total flow rate of the remaining gas (equivalent to the differential flow rate) added to the target flow rate by operating the gas is discharged from the compressor main body 140 to the high-pressure pipe 144. Since the release valve command signal R is determined such that the flow rate of the bypass pipe 158 is equivalent to its remaining flow rate, the operating gas is recovered from the high-pressure pipe 144 to the low-pressure pipe 142 at the remaining flow rate. Accordingly, the compressor units 102 and 104 can supply the working gas to the refrigerator 12 at a target flow rate. No structural design changes are required to prevent or mitigate resonance that may occur in compressor units driven by inverters for cryogenic refrigerators, and to ensure the required discharge flow rate. [0112] In addition, when the target flow rate is between the first discharge flow rate and the second discharge flow rate, the inverter command signal E is determined so that the operating frequency is set to the second operating frequency range, instead of fixing the operating frequency to The second value. In this case, since the operating frequency takes a value larger than the second value, the discharge flow rate of the compressor body 140 increases. The remaining flow rate can be offset by increasing the opening degree of the release valve 162 and increasing the flow rate of the bypass pipe 158. However, if the operating frequency is small, power consumption can be reduced. Therefore, as described above, it is preferable to set the operating frequency to the second value. [0113] Furthermore, by referring to the output distribution table 181, when the target flow rate is between the lower limit discharge flow rate and the first discharge flow rate, the compressor controller 168 determines the inverter command signal E so that the operation frequency is set to the first operation Frequency interval. At the same time, the compressor controller 168 decides the release valve command signal R, so that the release valve 162 is closed. In this case, only the compressor inverter 170 controls the discharge flow rate of the compressor unit. The release valve 162 is not used in the discharge flow rate control. [0114] When the target flow rate is between the second discharge flow rate and the upper limit discharge flow rate, the compressor controller 168 determines the inverter command signal E so that the operation frequency is set in the second operation frequency interval. At the same time, the compressor controller 168 decides the release valve command signal R, so that the release valve 162 is closed. In this case, only the compressor inverter 170 controls the discharge flow rate of the compressor unit. The release valve 162 is not used in the discharge flow rate control. [0115] In the case where the target flow rate is between zero and the lower limit discharge flow rate, the compressor controller 168 takes the lower limit value of the operating frequency to determine the frequency converter command signal E. At the same time, the compressor controller 168 decides to release the valve command signal R, so that the flow rate of the bypass pipe 158 is consistent with the differential flow rate. In this case, the discharge flow rate of the compressor unit is controlled only by the release valve 162. [0116] When the operating frequency is switched from the first value to the second value, the compressor controller may smooth the release valve command signal R and / or the inverter command signal E. The smoothing process may be, for example, a time-pass smoothing process such as a low-pass filter or an average moving process, or any other well-known smoothing process. Thereby, it is possible to prevent or mitigate the adverse effect on the helium gas flow rate caused by discontinuous changes in the release valve command signal R and / or the inverter command signal E. [0117] The present invention has been described based on the embodiments. The present invention is not limited to the above-mentioned embodiments, and various design changes can be made and various modifications exist, and the fact that such modifications also belong to the scope of the present invention is recognized by those skilled in the art. [0118] In one embodiment, the CP controller 100 can control the compressor units 102 and 104. The CP controller 100 may include a compressor controller 168. The CP controller 100 may include a compressor inverter 170. The CP controller 100 may include at least one of the following: a release valve driver 174, a control amount calculation unit 176, a deviation calculation unit 178, an output allocation processing unit 180, an output allocation table 181, an inverter instruction unit 182, and a release valve Command section 184.

[0119]

12‧‧‧Freezer

136‧‧‧Compressor Structure Department

140‧‧‧compressor body

142‧‧‧Low-pressure piping

144‧‧‧High-pressure piping

158‧‧‧Primary tube

168‧‧‧compressor controller

170‧‧‧compressor inverter

172‧‧‧Compressor motor

[0019] FIG. 1 is a diagram schematically showing an overall configuration of a cryopump system according to an embodiment of the present invention. [FIG. 2] A cross-sectional view schematically showing a cryopump according to an embodiment of the present invention. [FIG. 3] A diagram schematically showing a compressor unit according to an embodiment of the present invention. [Fig. 4] is a control block diagram related to the cryopump system of this embodiment. [Fig. 5] Fig. 5 is a diagram for explaining a control flow of operation control of a compressor unit according to an embodiment of the present invention. [FIG. 6] A diagram schematically illustrating an output allocation table according to an embodiment of the present invention.

Claims (5)

A compressor unit for a cryogenic refrigerator, comprising: a compressor structure section, comprising a compressor main body that compresses and discharges an operating gas of the cryogenic refrigerator, a variable operating frequency, and the compressor main body A compressor motor that operates, a high-pressure piping connected to the compressor main body so that the operating gas is discharged from the compressor main body, a low-pressure piping connected to the compressor main body so that the operating gas is sucked into the compressor main body, and bypassing the compressor The main body connects the high-pressure pipe to the bypass pipe of the low-pressure pipe, and a flow control valve provided on the bypass pipe so as to control the flow of the bypass pipe according to a valve designated signal; a compressor inverter, which is based on frequency conversion A compressor command signal to control the operating frequency of the compressor motor; and a compressor controller configured to determine the valve designation signal and the inverter instruction signal so that an operating gas is supplied from the compressor unit to the pole at a target flow rate. Low-temperature freezer; range of values that can be used for the aforementioned operating frequency Limited to the first operating frequency interval from the lower limit value greater than zero to the first value, and the second operating frequency interval from the second value to the upper limit value, the second value is greater than the first value; the first The value and the second value are determined so that the unused frequency range from the first value to the second value includes at least one natural frequency regarding at least a part of the compressor structure portion; the lower limit value of the operating frequency. The first value, the second value, and the upper limit value respectively correspond to the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge flow rate of the compressor main body; When the discharge flow rate is between the second discharge flow rate, the compressor controller determines the inverter command signal so that the operation frequency is set in the second operation frequency range, and determines the valve designation signal so that the side The flow rate of the wild tube is the same as the differential flow rate minus the target flow rate from the discharge flow rate of the compressor body obtained according to the instruction signal of the inverter; When the frequency is switched from the first value to the second value, the smoothing process of the embodiment of the valve of the compressor controller specified signal and / or the drive command signal. For example, if the compressor unit of claim 1, wherein the target flow rate is between the first discharge flow rate and the second discharge flow rate, the compressor controller takes the second value at the operation frequency to determine the foregoing. Inverter command signal. For example, the compressor unit of claim 1 or 2, wherein the compressor controller determines the instruction signal of the inverter when the target flow rate is between the lower limit discharge flow rate and the first discharge flow rate, so that the operating frequency It is set in the first operating frequency range, and the valve designation signal is determined so that the flow control valve is closed. When the target flow rate is between the second discharge flow rate and the upper limit discharge flow rate, the inverter instruction signal is determined. So that the operating frequency is set in the second operating frequency range, and the valve designation signal is determined so that the flow control valve is closed. For example, if the compressor unit of claim 1 or 2, wherein the target flow rate is between zero and the lower limit discharge flow rate, the compressor controller takes the lower limit value at the operating frequency to determine the inverter instruction signal, And the flow rate of the bypass pipe is consistent with the differential flow rate to determine the valve designation signal. A cryopump system comprising: a cryopump comprising a cryogenic plate and a cryogenic freezer for cooling the cryogenic plate; a compressor unit comprising: a compressor for compressing and ejecting an operating gas of a cryogenic freezer A compressor main body, a compressor motor having a variable operating frequency and operating the compressor main body, a high-pressure pipe connected to the compressor main body so that the operating gas is discharged from the compressor main body, and connected to the compressor main body so that the operating gas is sucked into The low-pressure piping of the compressor main body, the bypass pipe bypassing the compressor body and connecting the high-pressure pipe to the low-pressure pipe, and the bypass pipe provided to control the flow of the bypass pipe according to a valve designated signal Flow control valve; compressor inverter that controls the aforementioned operating frequency of the compressor motor in accordance with the inverter command signal; and a controller that determines the valve designated signal and the inverter command signal to make the actuating gas to The target flow rate is supplied from the compressor unit to the cryogenic refrigerator; The range of values that the operating frequency can adopt is limited in advance to a first operating frequency interval from a lower limit value greater than zero to a first value, and a second operating frequency interval from a second value to an upper limit value. The value is greater than the aforementioned first value; the aforementioned first value and the aforementioned second value are determined so that the unused frequency range from the aforementioned first value to the aforementioned second value includes at least one natural at least part of the compressor structure portion Frequency; the lower limit value, the first value, the second value, and the upper limit value of the operating frequency correspond to the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge of the compressor body, respectively. Flow rate; when the target flow rate is between the first discharge flow rate and the second discharge flow rate, the controller determines the inverter command signal so that the operation frequency is set in the second operation frequency range, and determines The valve designation signal causes the flow rate of the bypass pipe to be subtracted from the discharge flow rate of the compressor body obtained from the frequency converter command signal to the target flow rate. Consistent differential flow rate; when the operating frequency is switched from the first value to the second value, the valve controller to specify the signal and / or the drive command signal smoothing process.