CN110234877B

CN110234877B - Compressor unit and cryopump system for ultra-low temperature refrigerator

Info

Publication number: CN110234877B
Application number: CN201880007941.4A
Authority: CN
Inventors: 小川智浩; 木村敏之
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2017-02-07
Filing date: 2018-02-02
Publication date: 2020-11-20
Anticipated expiration: 2038-02-02
Also published as: WO2018147179A1; TWI677626B; US20190360496A1; JP2018127929A; KR20190116263A; CN110234877A; TW201833438A

Abstract

The present invention provides a simple method for dealing with vibration of an inverter-driven compressor unit for an ultra-low temperature refrigerator. The compressor unit is provided with a flow control valve for controlling the flow rate of the bypass pipe in accordance with a valve command signal, a compressor inverter (170), and a compressor controller (168). The range of values that can be used for the operating frequency is limited in advance to the 1 st operating frequency interval from the lower limit value to the 1 st value and the 2 nd operating frequency interval from the 2 nd value to the upper limit value, and the non-use frequency interval from the 1 st value to the 2 nd value includes the natural frequency of the compressor structural part. When the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate, the compressor controller (168) determines an inverter command signal so that the operation frequency is set in the 2 nd operation frequency range, and determines a valve command signal so that the flow rate of the bypass pipe matches a differential flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body obtained from the inverter command signal.

Description

Compressor unit and cryopump system for ultra-low temperature refrigerator

Technical Field

The present invention relates to a compressor unit and a cryopump system for an ultra-low temperature refrigerator.

Background

Conventionally, there is known a vibration suppression technique for changing an operating frequency of a compressor when a detection output of a vibration sensor is large in an inverter compressor, which is a so-called inverter compressor having an inverter and a variable operating frequency.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2001-317470

Disclosure of Invention

Technical problem to be solved by the invention

It is an exemplary object of an embodiment of the present invention to provide a simple method of treating vibration with respect to an inverter-driven compressor unit for an ultra-low-temperature freezer.

Means for solving the technical problem

According to an embodiment of the present invention, a compressor unit for an ultra-low-temperature refrigerator is provided. The compressor unit is provided with: a compressor structure, comprising: a compressor main body that compresses and discharges working gas of the ultra-low-temperature refrigerator; a compressor motor which has a variable operating frequency and operates a compressor main body; a high-pressure pipe connected to the compressor main body to discharge the working gas from the compressor main body; a low-pressure pipe connected to the compressor main body to suck the working gas into the compressor main body; a bypass pipe that bypasses the compressor main body and connects the high-pressure pipe to the low-pressure pipe; and a flow control valve provided in the bypass pipe to control a flow rate of the bypass pipe in accordance with the valve command signal; a compressor inverter for controlling the operation frequency of the compressor motor according to the inverter command signal; and a compressor controller configured to determine the valve command signal and the inverter command signal so that the working gas is supplied from the compressor unit to the ultra-low-temperature refrigerator at a target flow rate. The range of values that can be adopted for the operating frequency is previously defined in the 1 st operating frequency interval from the lower limit value to the 1 st value that is greater than zero, and the 2 nd operating frequency interval from the 2 nd value to the upper limit value, with the 2 nd value being greater than the 1 st value. The unused frequency range from the 1 st value to the 2 nd value, which is defined as the 1 st value to the 2 nd value, includes at least one natural frequency for at least a part of the compressor structure. The lower limit value, the 1 st value, the 2 nd value and the upper limit value of the operation frequency correspond to the lower limit discharge flow rate, the 1 st discharge flow rate, the 2 nd discharge flow rate and the upper limit discharge flow rate of the compressor body, respectively. When the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate, the compressor controller determines the inverter command signal so that the operation frequency is set in the 2 nd operation frequency section, and determines the valve command signal so that the flow rate of the bypass pipe matches a differential flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body obtained from the inverter command signal.

According to one embodiment of the present invention, a cryopump system includes: a cryopump including a cryopanel and a cryogenic refrigerator for cooling the cryopanel; a compressor unit including a compressor structure, the compressor structure including: a compressor main body that compresses and discharges working gas of the ultra-low-temperature refrigerator; a compressor motor that operates the compressor main body while varying an operating frequency thereof; a high-pressure pipe connected to the compressor main body to discharge working gas from the compressor main body; a low-pressure pipe connected to the compressor main body to suck a working gas into the compressor main body; a bypass pipe that bypasses the compressor main body and connects the high-pressure pipe to the low-pressure pipe; and a flow control valve provided in the bypass pipe to control a flow rate of the bypass pipe in accordance with a valve command signal; a compressor inverter controlling the operating frequency of the compressor motor according to an inverter command signal; and a controller configured to determine the valve command signal and the inverter command signal so that the working gas is supplied from the compressor unit to the ultra-low-temperature refrigerator at a target flow rate. The range of values that can be adopted for the operating frequency is previously defined in the 1 st operating frequency interval from the lower limit value to the 1 st value that is greater than zero, and the 2 nd operating frequency interval from the 2 nd value to the upper limit value, with the 2 nd value being greater than the 1 st value. The unused frequency range in which the 1 st and 2 nd values are determined as the 1 st to 2 nd values includes at least one natural frequency with respect to at least a part of the compressor structure. The lower limit value, the 1 st value, the 2 nd value and the upper limit value of the operation frequency correspond to the lower limit discharge flow rate, the 1 st discharge flow rate, the 2 nd discharge flow rate and the upper limit discharge flow rate of the compressor body, respectively. When the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate, the controller determines the inverter command signal so that the operating frequency is set in the 2 nd operating frequency range, and determines the valve command signal so that the flow rate of the bypass pipe matches a differential flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body obtained from the inverter command signal.

In addition, any combination of the above-described constituent elements, constituent elements and expressions of the present invention, among methods, apparatuses, systems, and the like, is also effective as an embodiment of the present invention.

Effects of the invention

According to the present invention, a simple method for dealing with vibration of an inverter-driven compressor unit used in an ultra-low-temperature refrigerator can be provided.

Drawings

Fig. 1 is a diagram schematically showing the overall configuration of a cryopump system according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view schematically showing a cryopump according to an embodiment of the present invention.

Fig. 3 is a diagram schematically showing a compressor unit according to an embodiment of the present invention.

Fig. 4 is a control block diagram of the cryopump system according to the present embodiment.

Fig. 5 is a diagram for explaining a control flow of the operation control of the compressor unit according to the embodiment of the present invention.

Fig. 6 is a diagram schematically illustrating an output allocation table according to an embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and overlapping description is appropriately omitted. The following configurations are illustrative and do not limit the scope of the present invention. In the following description, the sizes and thicknesses of the respective constituent members in the drawings referred to are for convenience of description, and do not necessarily represent actual sizes or ratios.

A cryogenic system is known which includes a cryogenic refrigerator and a compressor unit for supplying a working gas to the refrigerator. As an example of the cryogenic system, a system including a cryogenic apparatus (e.g., a cryopump) having a cryogenic refrigerator as a cooling source is also known. In the cryogenic system, the operating frequency of the compressor unit may be controlled using a pressure target value and a pressure measurement value, for example, so that the differential pressure between the high-pressure side and the low-pressure side of the working gas in the refrigerator matches a set value. This control helps to reduce the power consumption of the system, since the target working gas flow rate required by the refrigerator can be provided at the optimum (minimum) operating frequency.

It is assumed that the operating frequency range used in the inverter includes the natural frequency of the mechanical components such as the piping of the compressor unit. The compressor unit in operation itself becomes a source of vibration. If the operating frequency value is close to the natural frequency, resonance may occur in the mechanical structure of the compressor unit. Excessive vibration and noise, fatigue of structural members are undesirable.

In order to avoid these problems, it is preferable to prohibit the use of a value of the operating frequency close to the natural frequency. However, this means that in the case where the optimum operating frequency value is close to the natural frequency, this value is not used instead of using a value deviating 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 for the flow rate of the working gas required for the refrigerator. When the operating frequency is changed to a larger value, the power consumption of the compressor unit increases, and this leads to a disadvantage that the advantage of reducing the power consumption of the inverter control cannot be sufficiently obtained.

As a fundamental solution, it is also conceivable to modify the design of the compressor unit in such a way that the natural frequency of the mechanical component is not included in the operating frequency range used. However, such design changes are time-consuming and laborious.

According to an embodiment of the present invention, a compressor unit for an ultra-low-temperature refrigerator is provided. The compressor unit is provided with: a compressor structure, comprising: a compressor main body that compresses and discharges working gas of the ultra-low-temperature refrigerator; a compressor motor which has a variable operating frequency and operates a compressor main body; a high-pressure pipe connected to the compressor main body to discharge the working gas from the compressor main body; a low-pressure pipe connected to the compressor main body to suck the working gas into the compressor main body; a bypass pipe that bypasses the compressor main body and connects the high-pressure pipe to the low-pressure pipe; and a flow control valve provided in the bypass pipe to control a flow rate of the bypass pipe in accordance with the valve command signal; a compressor inverter for controlling the operation frequency of the compressor motor according to the inverter command signal; and a compressor controller configured to determine the valve command signal and the inverter command signal to supply the working gas from the compressor unit to the ultra-low-temperature freezer at a target flow rate. The range of values that can be adopted for the operating frequency is previously defined in the 1 st operating frequency interval from the lower limit value to the 1 st value that is greater than zero, and the 2 nd operating frequency interval from the 2 nd value to the upper limit value, with the 2 nd value being greater than the 1 st value. The unused frequency range from the 1 st value to the 2 nd value, which is defined as the 1 st value to the 2 nd value, includes at least one natural frequency for at least a part of the compressor structure. The lower limit value, the 1 st value, the 2 nd value and the upper limit value of the operation frequency correspond to the lower limit discharge flow rate, the 1 st discharge flow rate, the 2 nd discharge flow rate and the upper limit discharge flow rate of the compressor body, respectively. When the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate, the compressor controller determines the inverter command signal so that the operation frequency is set in the 2 nd operation frequency section, and determines the valve command signal so that the flow rate of the bypass pipe matches a differential flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body obtained from the inverter command signal.

According to this embodiment, the unused section of the operating frequency is determined so as to include the natural frequency of the compressor structural part, and therefore resonance of the compressor structural part due to the operation of the compressor main body is less likely to occur. Since the inverter command signal is determined so that the operating frequency is set in the 2 nd operating frequency range, the working gas is discharged from the compressor main body to the high-pressure pipe at a total flow rate in which the surplus flow rate (the differential flow rate) is added to the target flow rate. Since the valve command signal is determined such that the flow rate of the bypass pipe corresponds to the surplus flow rate, the working gas is recovered from the high-pressure pipe to the low-pressure pipe, and the compressor unit can supply the working gas to the ultra-low-temperature refrigerator at a target flow rate.

In the case where the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate, the compressor controller may determine the inverter command signal in such a manner that the operation frequency takes the 2 nd value.

In the case where the target flow rate is between the lower limit discharge flow rate and the 1 st discharge flow rate, the compressor controller may determine the inverter command signal so that the operation frequency is set in the 1 st operation frequency section, and may determine the valve command signal so that the flow control valve is closed. In the case where the target flow rate is between the 2 nd discharge flow rate and the upper limit discharge flow rate, the compressor controller may determine the inverter command signal so that the operation frequency is set in the 2 nd operation frequency section, and may determine the valve command signal so that the flow control valve is closed.

In the case where the target flow rate is between zero and the lower limit discharge flow rate, the compressor controller may determine the inverter command signal so that the operating frequency takes the lower limit, and may determine the valve command signal so that the flow rate of the bypass piping coincides with the differential flow rate.

The compressor controller may perform smoothing on the valve command signal and/or the inverter command signal when the operating frequency is switched from the 1 st value to the 2 nd value.

Fig. 1 is a diagram schematically showing the overall configuration of a cryopump system 1000 according to an embodiment of the present invention. The cryopump system 1000 is used to evacuate the vacuum apparatus 300. The vacuum apparatus 300 is a vacuum processing apparatus that processes an object in a vacuum environment, and is used in a semiconductor manufacturing process, such as an ion implantation apparatus and a sputtering apparatus.

The cryopump system 1000 includes a plurality of cryopumps 10. These cryopumps 10 are installed in one or more vacuum chambers (not shown) of the vacuum apparatus 300, and are used to increase the degree of vacuum inside the vacuum chambers to a level required for a desired program. 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 degree of vacuum of the order of 10-5Pa to 10-8Pa can be achieved in the vacuum chamber. In the illustrated example, 11 cryopumps 10 are included in the cryopump system 1000. The plurality of cryopumps 10 may be cryopumps each having the same exhaust performance, or may be cryopumps having different exhaust performances.

The cryopump system 1000 is provided with a CP controller 100. CP controller 100 controls cryopump 10 and

compressor units

102, 104. The CP controller 100 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM used as a work area for storing data and execution programs, an input/output interface, a memory, and the like. The CP controller 100 is also configured to be able to communicate with a host controller (not shown) for controlling the vacuum apparatus 300. The host controller of the vacuum apparatus 300 may be referred to as a host controller that integrates the components of the vacuum apparatus 300 including the cryopump system 1000.

The CP controller 100 is configured separately 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 as to be able to communicate with each other. The cryopump 10 is provided with an IO module 50 (see fig. 4) for processing input and output, respectively, which communicates with the CP controller 100. The CP controller 100 is connected to each IO module 50 through a control communication line. The control communication lines between the cryopump 10 and the CP controller 100 and the control communication lines between the

compressor units

102 and 104 and the CP controller 100 are indicated by broken lines in fig. 1. The CP controller 100 may be integrated with either the cryopump 10 or the

compressor units

102 and 104.

The CP controller 100 may be constituted by a single controller, or may include a plurality of controllers each implementing the same or different functions. For example, the CP controller 100 may include a compressor controller provided in each compressor unit and determining a control amount of each compressor unit, and a cryopump controller that collectively includes a cryopump system.

The cryopump system 1000 includes a plurality of compressor units including at least a 1 st compressor unit 102 and a 2 nd compressor unit 104. The compressor unit is provided for circulating the working gas in a closed fluid passage including the cryopump 10. The compressor unit recovers the working gas from the cryopump 10, compresses the working gas, and then feeds the working gas to the cryopump 10 again. The compressor unit is located remotely from the vacuum apparatus 300 or in the vicinity of the vacuum apparatus 300. The compressor unit is operated according to a control amount determined by a compressor controller 168 (refer to fig. 4). Or, operates according to the control amount determined by the CP controller 100.

A cryopump system 1000 having 2

compressor units

102 and 104 will be described below as a representative example, but the present invention is not limited thereto. A cryopump system 1000 in which 3 or more compressor units are connected in parallel to a plurality of cryopumps 10 may be configured in the same manner as the

compressor units

102 and 104. The cryopump system 1000 shown in fig. 1 includes the plurality of cryopumps 10 and the plurality of

compressor units

102 and 104, respectively, but 1 cryopump 10 or one

compressor unit

102 or 104 may be used.

The plurality of cryopumps 10 and the plurality of

compressor units

102 and 104 are connected by a working gas piping system 106. The piping system 106 is connected in parallel to the plurality of cryopumps 10 and the plurality of

compressor units

102 and 104, and is configured to circulate the working gas between the plurality of cryopumps 10 and the plurality of

compressor units

102 and 104. Each of the plurality of compressor units is connected in parallel to 1 cryopump 10, and each of the plurality of cryopumps 10 is connected in parallel to 1 compressor unit by the piping system 106.

The piping system 106 includes an internal piping 108 and an external piping 110. The internal pipe 108 is formed inside the vacuum apparatus 300, and includes an internal supply line 112 and an internal return line 114. The external pipe 110 is provided outside the vacuum apparatus 300, and includes an external supply line 120 and an external return line 122. The external piping 110 connects the vacuum apparatus 300 and the plurality of

compressor units

102 and 104.

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. The internal supply line 112 is connected to one end of an external supply line 120 of the external pipe 110 at an air supply port 116 of the vacuum apparatus 300, and the internal return line 114 is connected to one end of an external return line 122 of the external pipe 110 at an air exhaust port 118 of the vacuum apparatus 300.

The other end of the external supply line 120 is connected to a 1 st manifold 124 and the other end of the external return line 122 is connected to a 2 nd manifold 126. One end of a 1 st discharge pipe 128 of the 1 st compressor unit 102 and one end of a 2 nd discharge pipe 130 of the 2 nd compressor unit 104 are connected to the 1 st manifold 124. The other ends of the 1 st discharge pipe 128 and the 2 nd discharge pipe 130 are connected to the discharge ports 148 of the

corresponding compressor units

102 and 104, respectively (see fig. 3). One end of a 1 st suction pipe 132 of the 1 st compressor unit 102 and one end of a 2 nd suction pipe 134 of the 2 nd compressor unit 104 are connected to the 2 nd manifold 126. The other ends of the 1 st suction pipe 132 and the 2 nd suction pipe 134 are connected to the suction ports 146 (see fig. 3) of the

corresponding compressor units

102 and 104, respectively.

In this manner, a common supply line for collecting the working gas delivered from each of the plurality of

compressor units

102 and 104 and supplying the working gas to the plurality of cryopumps 10 is constituted by the internal supply line 112 and the external supply line 120. A common return line for collecting the working gas discharged from the plurality of cryopumps 10 and returning the working gas to the plurality of

compressor units

102 and 104 is constituted by an internal return line 114 and an external return line 122. Each of the plurality of compressor units is connected to the common pipe line by a separate pipe attached to each compressor unit. A manifold for joining the individual pipes is provided at a connection portion between the individual pipe and the common pipe. The 1 st manifold 124 merges the individual pipes at the supply side, and the 2 nd manifold 126 merges the individual pipes at the recovery side.

Depending on the arrangement of various devices in the location where the cryopump system 1000 is used (e.g., a semiconductor manufacturing plant), the common line may have a relatively long length (different from that shown). By collecting the working gas in the common line, the overall piping length can be shortened as compared with the case where a plurality of compressors are connected to the vacuum apparatus, respectively. Moreover, since a piping structure is adopted in which a plurality of compressors are connected to each of the targets to which the working gas is supplied (for example, each of the cryopumps 10 in the cryopump system 1000), redundancy is also provided. The plurality of compressors are arranged in parallel in each object (for example, a cryopump) and operated, thereby sharing the load on the plurality of compressors.

Fig. 2 is a sectional view schematically showing a cryopump 10 according to an embodiment of the present invention. The cryopump 10 includes a 1 st cryopanel cooled to a 1 st cooling temperature level and a 2 nd cryopanel cooled to a 2 nd cooling temperature level lower than the 1 st cooling temperature level. On the 1 st cryopanel, gas having a low vapor pressure in the 1 st cooling temperature class is captured by condensation and discharged. For example, a gas having a vapor pressure lower than a reference vapor pressure (for example, 10-8Pa) is discharged. On the 2 nd cryopanel, gas having a low vapor pressure in the 2 nd cooling temperature class is captured by condensation and discharged. An adsorption region is formed on the upper surface of the 2 nd cryopanel to trap non-condensable gases that are not condensed due to high vapor pressure even in the 2 nd temperature class. The adsorption region is formed by, for example, providing an adsorbent on the plate surface. The non-condensable gas is adsorbed in the adsorption region cooled to the 2 nd temperature level and discharged.

The cryopump 10 shown in fig. 2 includes a refrigerator 12, a panel structure 14, and a heat shield 16. The refrigerator 12 generates cold by a heat cycle in which working gas is sucked and expanded inside to be discharged. The panel structure 14 includes a plurality of cryopanels, which are cooled by the refrigerator 12. An ultra-low temperature surface for capturing and discharging gas by condensation or adsorption is formed on the surface of the plate. An adsorbent such as activated carbon for adsorbing gas is usually provided on the front surface (e.g., the back surface) of the cryopanel. The heat shield 16 is provided to protect the panel structure 14 from the surrounding radiant heat.

The cryopump 10 is a so-called vertical cryopump. The vertical cryopump is a cryopump in which the refrigerator 12 is inserted and disposed along the axial direction of the heat shield 16. The present invention can be applied to a so-called transverse cryopump as well. The horizontal cryopump is a cryopump in which the 2 nd stage cooling stage of the refrigerator is inserted and arranged in a direction (generally, orthogonal direction) intersecting the axial direction of the heat shield 16. Fig. 1 schematically shows a horizontal cryopump 10.

The freezer 12 is a gifford-mcmahon freezer (so-called GM freezer). The refrigerator 12 is a 2-stage refrigerator, and includes a 1 st-stage cylinder 18, a 2 nd-stage cylinder 20, a 1 st cooling stage 22, a 2 nd cooling stage 24, and a refrigerator motor 26. The stage 1 cylinder 18 and the stage 2 cylinder 20 are connected in series, and each has a stage 1 displacer and a stage 2 displacer (not shown) connected to each other. The stage 1 displacer and the stage 2 displacer are internally provided with a cold storage material. The refrigerator 12 may be a refrigerator other than a 2-stage GM refrigerator, and for example, a single-stage GM refrigerator, a pulse tube refrigerator, or a solvay refrigerator may be used.

The refrigerator 12 includes a flow path switching mechanism that periodically switches a flow path of the working gas so as to periodically repeat the suction and discharge of the working gas. The flow path switching mechanism includes, for example, a valve portion and a drive portion that drives the valve portion. The valve unit is, for example, a rotary valve, and the drive unit 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-drive mechanism operated by a linear motor.

A freezer motor 26 is provided at one end of the stage 1 cylinder 18. The freezer motor 26 is provided inside a motor case 27 formed at an end of the 1 st stage cylinder 18. The refrigerator motor 26 is connected to the stage 1 displacer and the stage 2 displacer so that the stage 1 displacer and the stage 2 displacer can reciprocate in the stage 1 cylinder 18 and the stage 2 cylinder 20, respectively. The refrigerator motor 26 is connected to a movable valve (not shown) provided inside the motor case 27 so as to be rotatable in the forward and reverse directions.

The 1 st cooling stage 22 is provided at an end portion of the 1 st stage cylinder 18 on the 2 nd stage cylinder 20 side, that is, at a connecting portion between the 1 st stage cylinder 18 and the 2 nd stage cylinder 20. And, a 2 nd cooling stage 24 is provided at the end of the 2 nd stage cylinder 20. The 1 st cooling stage 22 and the 2 nd cooling stage 24 are fixed to the 1 st cylinder 18 and the 2 nd cylinder 20, respectively, by welding, for example.

The refrigerator 12 is connected to the

compressor unit

102 or 104 through an air supply port 42 and an air discharge port 44 provided outside the motor case 27. The connection relationship between the cryopump 10 and the

compressor units

102 and 104 is as described with reference to fig. 1.

The refrigerator 12 expands the high-pressure working gas (e.g., helium gas) supplied from the

compressor units

102 and 104 inside, and thereby generates cold in the 1 st cooling stage 22 and the 2 nd cooling stage 24. The

compressor units

102 and 104 collect the working gas expanded by the refrigerator 12, pressurize the working gas again, and supply the working gas to the refrigerator 12.

Specifically, first, the high-pressure working 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 communicate with each other. When the internal space of the refrigerator 12 is filled with the high-pressure working 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 working gas is expanded and recovered to the

compressor units

102, 104. In synchronization with the operation of the movable valve, the stage 1 displacer and the stage 2 displacer reciprocate in the stage 1 cylinder 18 and the stage 2 cylinder 20, respectively. By repeating such a heat cycle, the refrigerator 12 chills the 1 st cooling stage 22 and the 2 nd cooling stage 24.

The 2 nd cooling station 24 is cooled to a lower temperature than the 1 st cooling station 22. The 2 nd cooling stage 24 is cooled to, for example, 10K to 20K, and the 1 st cooling stage 22 is cooled to, for example, 80K to 100K. A 1 st temperature sensor 23 for measuring the temperature of the 1 st cooling stage 22 is attached to the 1 st cooling stage 22, and a 2 nd temperature sensor 25 for measuring the temperature of the 2 nd cooling stage 24 is attached to the 2 nd cooling stage 24.

The heat shield 16 is fixed in a thermally connected state on the 1 st cooling stage 22 of the refrigerator 12, and the plate structure 14 is fixed in a thermally connected state on the 2 nd cooling stage 24 of the refrigerator 12. Thus, the heat shield 16 is cooled to the same degree as the 1 st cooling stage 22 and the plate structure 14 is cooled to the same degree as the 2 nd cooling stage 24. The heat shield 16 is formed in a cylindrical shape having an opening 31 at one end. The opening 31 is defined by an end inner surface of the cylindrical side surface of the heat shield 16.

On the other hand, a closed portion 28 is formed on the other end of the heat shield 16 on the side opposite to the opening portion 31, that is, on the pump bottom portion 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 1 st cooling stage 22 of the refrigerator 12. Thereby, a columnar inner space 30 is formed inside the heat shield 16. The refrigerator 12 protrudes into the internal space 30 along the central axis of the heat shield 16, and the 2 nd cooling stage 24 is inserted into the internal space 30.

In the case of the transverse cryopump, the closing portion 28 is normally completely closed. The refrigerator 12 is disposed to protrude toward the internal space 30 in a direction perpendicular to the central axis of the heat shield 16 from a refrigerator mounting opening formed in a side surface of the heat shield 16. The 1 st cooling stage 22 of the refrigerator 12 is attached to the refrigerator-attaching opening of the heat shield 16, and the 2 nd cooling stage 24 of the refrigerator 12 is disposed in the internal space 30. The plate structure 14 is mounted on the 2 nd cooling stage 24. Thereby, the panel structure 14 is disposed in the internal space 30 of the heat shield 16. The panel structure 14 may be mounted to the 2 nd cooling stage 24 via a suitably shaped panel mounting assembly.

A baffle 32 is attached to the opening 31 of the heat shield 16. The baffle 32 is provided at a distance from the plate structure 14 in the central axis direction of the heat shield 16. The baffle 32 is attached to the end portion of the heat shield 16 on the opening portion 31 side, and is cooled to the same temperature as the heat shield 16. The baffle 32 may be formed in a concentric circle shape or may be formed in another shape such as a lattice shape when viewed from the vacuum chamber 80 side. Further, a gate valve (not shown) is provided between the baffle 32 and the vacuum chamber 80. The gate valve is closed when the cryopump 10 is regenerated, and is opened when the vacuum chamber 80 is evacuated by the cryopump 10, for example. The vacuum chamber 80 is provided in, for example, a vacuum apparatus 300 shown in fig. 1.

The heat shield 16, the baffle 32, the plate structure 14, and the 1 st cooling stage 22 and the 2 nd cooling stage 24 of the refrigerator 12 are housed inside a pump case 34. The pump casing 34 is formed by connecting 2 cylinders having different diameters in series. The pump housing 34 has a large-diameter cylindrical end portion open and a flange portion 36 for connection with the vacuum chamber 80 is formed extending radially outward. The small-diameter cylindrical side end of the pump case 34 is fixed to the motor case 27 of the refrigerator 12. The cryopump 10 is fixed in an airtight manner to the exhaust opening of the vacuum chamber 80 via the flange portion 36 of the pump case 34, and forms an airtight space integrated with the internal space of the vacuum chamber 80. The pump casing 34 and the heat shield 16 are both formed in a cylindrical shape and are coaxially arranged. The inner diameter of the pump casing 34 is slightly larger than the outer diameter of the heat shield 16, so that the heat shield 16 is disposed at a slight interval from the inner surface of the pump casing 34.

When the cryopump 10 is operated, first, before the operation, the inside of the vacuum chamber 80 is roughly pumped to a level of 1Pa to 10Pa by using another appropriate rough pump. Thereafter, the cryopump 10 is operated. The 1 st cooling stage 22 and the 2 nd cooling stage 24 are cooled by driving of the refrigerator 12, and the heat shield 16, the baffle 32, and the plate structure 14 thermally connected thereto are also cooled.

The cooled baffle 32 cools gas molecules that have flown from the vacuum chamber 80 into the cryopump 10, condenses the gas (for example, moisture) whose vapor pressure has sufficiently decreased at the cooling temperature on the surface, and discharges the gas. The gas whose vapor pressure has not sufficiently decreased at the cooling temperature of the baffle 32 passes through the baffle 32 and then enters the interior of the heat shield 16. Among the introduced gas molecules, a gas (for example, argon gas or the like) whose vapor pressure is sufficiently lowered at the cooling temperature of the plate structure 14 is condensed on the surface of the plate structure 14 and discharged. The gas (for example, hydrogen gas or the like) whose vapor pressure has not sufficiently decreased even at the cooling temperature is adsorbed and discharged by the adsorbent which is bonded to the surface of the plate structure 14 and cooled. In this way, the cryopump 10 can make the degree of vacuum inside the vacuum chamber 80 a desired level.

Fig. 3 is a view schematically showing the 1 st compressor unit 102 according to the embodiment of the present invention. The 2 nd compressor unit 104 also has the same structure as the 1 st compressor unit 102 in the present embodiment. The compressor unit 102 includes a compressor body 140 for increasing the pressure of the gas, a low-pressure pipe 142 for supplying low-pressure gas supplied from the outside to the compressor body 140, and a high-pressure pipe 144 for delivering high-pressure gas compressed by the compressor body 140 to the outside.

As shown in fig. 1, the low-pressure gas is supplied to the 1 st compressor unit 102 through the 1 st suction pipe 132. The 1 st compressor unit 102 receives the return gas from the cryopump 10 through the suction port 146, and the working gas is sent to the low pressure pipe 142. The suction port 146 is provided at the end of the low-pressure pipe 142 in the compressor housing 138 of the 1 st compressor unit 102. The low-pressure pipe 142 connects the suction port 146 and the suction port of the compressor body 140.

The low-pressure pipe 142 includes a tank 150 as a volume for removing pulsation included in the return gas in the middle. The reservoir 150 is provided between the suction port 146 and a branch toward a bypass mechanism 152 described later. The pulsation-removed working gas in the accumulator 150 is supplied to the compressor main body 140 through the low-pressure pipe 142. A filter for removing unwanted particles and the like from the gas may be provided inside the storage tank 150. A receiving port and a pipe for supplying the working gas from the outside may be connected between the tank 150 and the suction port 146.

The compressor main body 140 is, for example, a scroll type or a rotary pump, and performs a function of boosting a pressure of the sucked gas. The compressor main body 140 is provided with a compressor motor 172, and the compressor main body 140 is operated by the compressor motor 172. The compressor main body 140 sends the pressurized working gas to the high-pressure pipe 144. The compressor body 140 is configured to be cooled using oil, and an oil cooling pipe for circulating the oil is additionally provided to the compressor body 140. Therefore, the pressurized working gas is sent to the high-pressure pipe 144 in a state where a little oil is mixed therein.

Thus, an oil separator 154 is provided in the middle of the high-pressure pipe 144. The oil separated from the working gas by the oil separator 154 is returned to the low-pressure pipe 142, and may be returned to the compressor body 140 through the low-pressure pipe 142. A relief valve for releasing an excessively high pressure may be provided in the oil separator 154.

A heat exchanger (not shown) for cooling the high-pressure working gas sent from the compressor body 140 may be provided in the middle of the high-pressure pipe 144 connecting the compressor body 140 and the oil separator 154. The heat exchanger cools the working gas, for example by means of cooling water. The cooling water may be used to cool oil for cooling the compressor main body 140. The high-pressure pipe 144 may be provided with a temperature sensor for measuring the temperature of the working gas at least one of upstream and downstream of the heat exchanger.

The working gas passed through 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, from the working gas, a contaminant component that has not been removed by a contaminant removal mechanism in a flow path such as a filter or an oil separator 154 in the tank 150. The adsorber 156 removes the gasified oil component by, for example, adsorption.

The discharge port 148 is provided at the end of the high-pressure pipe 144 in the compressor housing 138 of the 1 st compressor unit 102. That is, the high-pressure pipe 144 connects the compressor body 140 and the discharge port 148, and an oil separator 154 and an adsorber 156 are provided midway therebetween. The working gas passing through the adsorber 156 is delivered to the cryopump 10 through the exhaust port 148.

The 1 st compressor unit 102 includes a bypass mechanism 152, and the bypass mechanism 152 includes a bypass pipe 158 connecting the low-pressure pipe 142 and the high-pressure pipe 144. In the illustrated embodiment, the bypass piping 158 branches off from the low-pressure piping 142 between the storage tank 150 and the compressor main body 140. The bypass pipe 158 branches off from the high-pressure pipe 144 between the oil separator 154 and the adsorber 156.

The bypass mechanism 152 includes a control valve for controlling the flow rate of the working gas bypassing the high-pressure pipe 144 to the low-pressure pipe 142 without being sent to the cryopump 10. In the illustrated embodiment, a 1 st control valve (also referred to as a pressure equalizing valve) 160 and a 2 nd control valve (also referred to as a relief 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 type solenoid valve. Thus, when the operation of the 1 st compressor unit 102 is stopped (that is, when the power supply to the 1 st 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 relief valve 162 is, for example, a normally closed solenoid valve. In the present embodiment, the relief valve 162 is used as a flow rate control valve of the bypass pipe 158 during operation of the 1 st compressor unit 102.

The 1 st compressor unit 102 includes a 1 st pressure sensor 164 for measuring the pressure of the return gas from the cryopump 10 and a 2 nd pressure sensor 166 for measuring the pressure of the feed gas to the cryopump 10. Since the feed gas is higher in pressure than the return gas in the operation of the 1 st compressor unit 102, the 1 st pressure sensor 164 and the 2 nd pressure sensor 166 are also referred to as a low pressure sensor and a high pressure sensor, respectively, hereinafter.

The 1 st pressure sensor 164 is provided for measuring the pressure in the low-pressure pipe 142, and the 2 nd pressure sensor 166 is provided for measuring the pressure in the high-pressure pipe 144. The 1 st pressure sensor 164 is provided in the tank 150, for example, and measures the pressure of the return gas from which pulsation has been removed in the tank 150. The 1 st pressure sensor 164 may be provided at any position of the low-pressure pipe 142. The 2 nd pressure sensor 166 is disposed between the oil separator 154 and the adsorber 156. The 2 nd pressure sensor 166 may be provided at any position of the high-pressure pipe 144.

The 1 st pressure sensor 164 and the 2 nd pressure sensor 166 may be provided outside the 1 st compressor unit 102, or may be provided in the 1 st suction pipe 132 and the 1 st discharge pipe 128, for example. The bypass mechanism 152 may be provided outside the 1 st compressor unit 102, and the 1 st suction pipe 132 and the 1 st discharge pipe 128 may be connected by a bypass pipe 158, for example.

The compressor structure 136 shown in fig. 3 includes a compressor main body 140, a low-pressure pipe 142, a high-pressure pipe 144, a suction port 146, a discharge port 148, a tank 150, a bypass mechanism 152, an oil separator 154, an adsorber 156, a bypass pipe 158, a pressure equalizing valve 160, a relief valve 162, a 1 st pressure sensor 164, a 2 nd pressure sensor 166, and a compressor motor 172. These components are housed in the compressor housing 138.

Fig. 4 is a control block diagram of the cryopump system 1000 according to the present embodiment. Fig. 4 shows the main parts of a cryopump system 1000 according to an embodiment of the invention. The details of the interior of one of the cryopumps 10 are shown, and the other cryopumps 10 are the same and are not shown. Similarly, the 1 st compressor unit 102 is shown in detail, and the 2 nd compressor unit 104 is the same as that of the first compressor unit, and therefore, the inside thereof is not shown.

As described above, the CP controller 100 is communicably connected to the IO module 50 of each cryopump 10. 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 the adjusted power to the refrigerator motor 26. The voltage and frequency to be supplied to the freezer motor 26 are controlled by the CP controller 100.

The CP controller 100 determines a command control amount based on the sensor output signal. The signal processing unit 54 transfers the command control amount transmitted from the CP controller 100 to the refrigerator inverter 52. For example, the signal processing unit 54 converts the 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 indicative of the operating frequency of the chiller motor 26. The signal processing unit 54 then transfers the outputs of the 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 transmits the signal to the CP controller 100.

Various sensors including the 1 st temperature sensor 23 and the 2 nd temperature sensor 25 are connected to the signal processing unit 54 of the IO module 50. As described above, the 1 st temperature sensor 23 measures the temperature of the 1 st cooling stage 22 of the refrigerator 12, and the 2 nd temperature sensor 25 measures the temperature of the 2 nd cooling stage 24 of the refrigerator 12. The 1 st temperature sensor 23 and the 2 nd temperature sensor 25 periodically measure the temperature of the 1 st cooling stage 22 and the 2 nd cooling stage 24, respectively, and output signals indicating the measured temperatures. The measurement values of the 1 st temperature sensor 23 and the 2 nd temperature sensor 25 are input to the CP controller 100 at predetermined intervals, and are stored and saved in a predetermined storage area of the CP controller 100.

The CP controller 100 controls the freezer 12 based on the temperature of the cryopanel. The CP controller 100 applies 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 refrigerator inverter command signal by feedback control so that the deviation between the target temperature of the 1 st-stage cryopanel and the measured temperature of the 1 st temperature sensor 23 is minimized. The refrigerator inverter command signal is given from the CP controller 100 to the refrigerator inverter 52 via the IO module 50. The chiller inverter 52 controls the operating frequency of the chiller motor 26 in accordance with the chiller inverter command signal. The rotational speed of the chiller motor 26, i.e., the frequency of the thermal cycle of the chiller 12, is determined based on the operating frequency of the chiller motor 26. The target temperature of the stage 1 cryopanel is determined to be a specification, for example, according to a program performed in the vacuum chamber 80. At this time, the 2 nd cooling stage 24 of the refrigerator 12 and the plate structure 14 are cooled to a temperature determined in accordance with the specification of the refrigerator 12 and the heat load from the outside.

When the measured temperature of the 1 st temperature sensor 23 is higher than the target temperature, the CP controller 100 outputs a chiller inverter command signal to the IO module 50 in order to increase the operating frequency of the chiller motor 26. In conjunction with the increase in the motor operating frequency, the frequency of the heat cycle in the refrigerator 12 also increases, and the 1 st cooling stage 22 of the refrigerator 12 is cooled to the target temperature. Conversely, when the measured temperature of the 1 st temperature sensor 23 is lower than the target temperature, the operating frequency of the chiller motor 26 decreases, and the 1 st cooling stage 22 of the chiller 12 is raised to the target temperature.

Generally, the target temperature of the 1 st cooling stage 22 is set to a constant value. Thus, the CP controller 100 outputs the refrigerator inverter command signal to increase the operating frequency of the refrigerator motor 26 when the heat load on the cryopump 10 increases, and outputs the refrigerator inverter command signal to decrease the operating frequency of the refrigerator motor 26 when the heat load on the cryopump 10 decreases. The target temperature may be varied as appropriate, and for example, the target temperature of the cryopanel may be set in order to achieve a target ambient gas pressure in the exhaust target volume. The CP controller 100 may also control the operating frequency of the chiller motor 26 so that the actual temperature of the 2 nd-stage cryopanel matches the target temperature.

In a typical cryopump, the frequency of the thermal cycle is set constant at all times. The operation is set at a relatively high frequency so that the cryopanel can be cooled rapidly from the room temperature to the pump operating temperature, and when the heat load from the outside is small, the cryopanel is heated by the heater to adjust the temperature of the cryopanel. Thereby power consumption becomes large. In contrast, in the present embodiment, since the heat cycle frequency is controlled in accordance with the heat load of the cryopump 10, a cryopump having excellent energy saving performance can be realized. Further, the heater is not necessarily provided, which contributes to reduction in power consumption.

CP controller 100 is communicatively coupled to compressor controller 168. The control unit of the cryopump system 1000 according to the embodiment of the present invention is configured by a plurality of controllers including the CP controller 100 and the compressor controller 168. In another embodiment, the control unit of the cryopump system 1000 may be configured by a single CP controller 100, and IO modules may be provided in the

compressor units

102 and 104 instead of the compressor controller 168. At this time, the IO module transfers a control signal between the CP controller 100 and each of the components of the

compressor units

102 and 104. Also, the compressor controller 168 may form a part of the CP controller 100.

The compressor controller 168 controls the 1 st compressor unit 102 according to a control signal from the CP controller 100 or independently from the CP controller 100. In one embodiment, the compressor controller 168 receives signals from the CP controller 100 indicative of various set points and uses the set points to control the 1 st compressor unit 102. The compressor controller 168 determines a command control amount based on 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 used as a work area for storing data or executing programs, an input/output interface, a memory, and the like.

Also, the compressor controller 168 transmits a signal indicating the operation state of the 1 st compressor unit 102 to the CP controller 100. The signal indicating the operation state includes, for example, the measured pressures of the 1 st pressure sensor 164 and the 2 nd pressure sensor 166, the opening degree or the control current of the relief valve 162, the operation frequency of the compressor motor 172, and the like.

The 1 st 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 and has a variable operating frequency, and is provided in the compressor main body 140. As with the refrigerator motor 26, various motors can be used as the compressor motor 172. Compressor controller 168 generates a compressor inverter command signal and outputs it to compressor inverter 170. The compressor inverter 170 controls the operating frequency of the compressor motor 172 according to the compressor inverter command signal. The rotation speed of the compressor motor 53 is controlled according to 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, for example, a commercial power source, in accordance with a compressor inverter command signal, and supplies the adjusted 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.

Various sensors including the 1 st pressure sensor 164 and the 2 nd pressure sensor 166 are connected to the compressor controller 168. As described above, the 1 st pressure sensor 164 periodically measures the pressure on the suction side of the compressor main body 140, and the 2 nd pressure sensor 166 periodically measures the pressure on the discharge side of the compressor main body 140. The measurement values of the 1 st pressure sensor 164 and the 2 nd pressure sensor 166 are input to the compressor controller 168 at predetermined intervals, and are stored and saved in a predetermined memory area of the compressor controller 168.

The relief valve 162 is connected to the compressor controller 168. A relief valve driver 174 for driving the relief valve 162 is additionally provided to the relief valve 162, and the relief valve driver 174 is connected to the compressor controller 168. The compressor controller 168 generates a relief valve command signal and outputs the same to the relief valve driver 174. The relief valve command signal determines the opening degree of the relief valve 162, and the relief valve driver 174 controls the relief valve 162 to the opening degree. Thus, the relief valve 162 is provided in the bypass pipe 158 to control the flow rate of the bypass pipe 158 in accordance with the relief valve command signal. Relief valve driver 174 may be assembled to compressor controller 168.

The compressor controller 168 controls the compressor main body 140 so that a differential pressure between the input and output ports of the compressor unit 102 (hereinafter, also referred to as a compressor differential pressure) is maintained at a target differential pressure. For example, the compressor controller 168 performs feedback control so as to set the pressure difference between the input and output ports of the compressor unit 102 to a constant value. In one embodiment, compressor controller 168 determines the compressor differential pressure from the measurements of 1 st pressure sensor 164 and 2 nd pressure sensor 166. The compressor controller 168 determines the operating frequency of the compressor motor 172 to bring the compressor differential pressure into agreement with a target value. Compressor controller 168 controls compressor inverter 170 to achieve the operating frequency. The target value of the differential pressure may be changed when the differential pressure constant control is executed.

By such constant control of the pressure difference, further reduction in power consumption can be achieved. When the heat load on the cryopump 10 and the refrigerator 12 is small, the heat cycle frequency in the refrigerator 12 is reduced by the above-described cryopanel temperature adjustment control. This reduces the amount of working gas required in the refrigerator 12. At this point, an amount of gas in excess of the desired amount may be delivered from the compressor unit 102. Accordingly, the pressure difference between the input and output ports of the compressor unit 102 tends to increase. However, in the present embodiment, the operating frequency of the compressor motor 172 is controlled so that the compressor differential pressure is constant. At this time, the operating frequency of the compressor motor 172 is reduced in order to reduce the differential pressure toward the target value. Thus, as in a typical cryopump, the power consumption can be reduced as compared with a case where the compressor is operated at a constant operation frequency all the time.

On the other hand, when the heat load on the cryopump 10 becomes large, the operating frequency of the compressor motor 172 is increased so that the compressor differential pressure becomes constant. Therefore, the amount of gas supplied to the refrigerator 12 can be sufficiently ensured, and thus, the deviation of the cryopanel temperature from the target temperature due to the increase in the thermal load can be suppressed to the minimum.

In particular, when the valves are opened on the high-pressure side to suck the working gas and the working gas are overlapped or extremely close to each other in the plurality of refrigerators 12, the total amount of the required gas increases. For example, when the compressor is operated only at a constant discharge flow rate or when the discharge pressure of the compressor is insufficient, the amount of gas supplied to the refrigerator in which the valve is opened later is smaller than that to the refrigerator in which the valve is opened first to suck the gas. The difference in the amount of the supplied gas between the refrigerators 12 causes variation in the refrigerating capacity between the refrigerators 12. In comparison with these cases, the differential pressure control is executed to sufficiently ensure the flow rate of the working gas to the refrigerator 12. The differential pressure control contributes to energy saving, and can suppress variation in refrigerating capacity among the plurality of refrigerators 12.

Fig. 5 is a diagram for explaining a control flow of the operation control of the compressor unit according to the embodiment of the present invention. The control process shown in fig. 5 is repeatedly executed by the compressor controller 168 at predetermined cycles during the operation of the cryopump 10. This process is performed independently of the

other compressor units

102, 104 in the respective compressor controllers 168 of the

respective compressor units

102, 104. In fig. 5, a portion of the operation process in the compressor controller 168 is divided by a dotted line, and a portion of the hardware operation of the

compressor units

102 and 104 is divided by a one-dot chain line.

The compressor controller 168 includes a control amount calculation unit 176. The control amount calculation unit 176 is configured to calculate a command control amount used for at least the differential pressure constant control, for example. 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 relief valve 162 to perform the differential pressure constant control. In another embodiment, the pressure difference constant control may be performed using only one of the operating frequency of the compressor motor 172 and the opening degree of the relief valve 162 as the command control amount. As will be described later, the control amount calculation unit 176 may be configured to calculate a command control amount for at least one of the differential pressure constant control, the discharge pressure control, and the suction pressure control.

As shown in fig. 5, a target differential pressure Δ P0 is preset and input in the compressor controller 168. The target differential pressure is set in the CP controller 100, for example, and is given to the compressor controller 168. The suction-side measured pressure PL is measured by the 1 st pressure sensor 164, and the discharge-side measured pressure PH is measured by the 2 nd pressure sensor 166, and is applied from each sensor to the compressor controller 168. Generally, the measured pressure PL of the 1 st pressure sensor 164 is lower than the measured pressure PH of the 2 nd pressure sensor 166.

The compressor controller 168 includes a deviation calculation unit 178, and the deviation calculation unit 178 calculates a measured differential pressure Δ P by subtracting the intake-side measured pressure PL from the discharge-side measured pressure PH, and further calculates a differential pressure deviation e by subtracting the measured differential pressure Δ P from the set differential pressure Δ P0. The control amount calculation unit 176 of the compressor controller 168 calculates the command control amount D from the differential pressure deviation e by predetermined control amount calculation processing including, for example, PD calculation or PID calculation.

As shown in the drawing, the compressor controller 168 may be provided with a deviation calculation unit 178 independently of the control amount calculation unit 176, and the control amount calculation unit 176 may be provided with the deviation calculation unit 178. Further, an integral calculation unit for multiplying the command control amount D for a predetermined time and applying the result to the output assignment processing unit 180 may be provided at a stage subsequent to the control amount calculation unit 176.

The compressor controller 168 includes an output assignment processing unit 180 that assigns the command control amount D to a 1 st command output value D1 and a 2 nd command output value D2. The output assignment processing section 180 determines the 1 st command output value D1 and the 2 nd command output value D2 according to the magnitude of the command control amount D value. The output assignment processing section 180 refers to the output assignment table 181, thereby determining the 1 st command output value D1 and the 2 nd command output value D2 from the command control amount D. The output assignment table 181 is prepared in advance and stored in the output assignment processing unit 180 or the compressor controller 168.

The command control amount D is a parameter corresponding to a target flow rate of the compressor unit. The command control amount D indicates the flow rate of the working gas to be delivered by the compressor unit to achieve a target pressure such as the target differential pressure Δ P0. In addition, the command control amount D need not directly indicate the target flow rate itself of the compressor unit. The command control amount D may be a parameter related to the target flow rate of the compressor unit by a function or a table, or an arbitrary parameter related to the target flow rate of the compressor unit.

The 1 st command output value D1 is a parameter corresponding to the operating frequency command value of the compressor motor 172. The 1 st command output value D1 may be a parameter associated with the operation frequency command value according to a function or a table, or an arbitrary parameter associated with the operation frequency command value. The 2 nd command output value D2 is a parameter corresponding to the opening degree command value of the relief valve 162. The 2 nd command output value D2 may be a parameter related to the opening degree command value by a function or a table, or an arbitrary parameter related to the opening degree command value.

The compressor controller 168 includes an inverter command unit 182 for generating a compressor inverter command signal E from a 1 st output command value D1, and a relief valve command unit 184 for generating a relief valve command signal R from a 2 nd output command value D2. The compressor inverter command signal E is given to the compressor inverter 170, and controls the operating frequency of the compressor main body 140, i.e., the compressor motor 172, according to the command. The compressor inverter command signal E is, for example, a voltage signal or other electrical signal representing an operating frequency command value. The relief valve command signal R is applied to the relief valve actuator 174, and the opening degree of the relief valve 162 is controlled in accordance with the command. The relief valve command signal R is an electric signal indicating an opening degree command value of the relief valve 162, and is, for example, a pulse output signal for driving a solenoid coil.

In this manner, the compressor controller 168 determines the relief valve command signal R and the compressor inverter command signal E to cause the working gas to be supplied from the

compressor units

102, 104 to the cryopump 10 (i.e., the refrigerator 12) at the target flow rate. The compressor controller 168 controls the opening degree of the relief valve 162 based on the determined relief valve command signal R. The compressor controller 168 outputs the relief valve command signal R to the relief valve driver 174, thereby opening the relief valve 162 in accordance with the relief valve command signal R. And, the compressor controller 168 controls the operation frequency of the compressor main body 140 according to the determined compressor inverter command signal E. The compressor controller 168 outputs the compressor inverter command signal E to the compressor inverter 170, whereby the operating frequency of the compressor motor 172 is controlled according to the compressor inverter command signal E.

The pressure of the helium gas as the working gas is determined based on the operating states of the compressor main body 140 and the relief valve 162 and the characteristics of the piping, the tank, and the like. The helium pressure thus determined is measured by the 1 st pressure sensor 164 and the 2 nd pressure sensor 166.

As described above, in each

compressor unit

102, 104, the pressure difference constant control is independently performed by each compressor controller 168. The compressor controller 168 performs feedback control to minimize (preferably set to zero) the differential pressure deviation e.

However, the deviation e shown in fig. 5 is not limited to the deviation of the pressure difference. In one embodiment, the compressor controller 168 may execute discharge pressure control in which a command control amount is calculated from a deviation between the discharge-side measured pressure PH and the 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 value, the compressor controller 168 may calculate the command control amount from a deviation from the discharge-side measured pressure PH. The upper limit value may be set empirically or experimentally as appropriate based on the maximum discharge pressure of the compressor that ensures the discharge capacity of the cryopump 10, for example.

This can suppress an excessive rise in the discharge pressure, and can further improve safety. Therefore, the discharge pressure control is an example of protection control for the compressor unit.

In one embodiment, the compressor controller 168 may execute control for calculating the suction pressure of the command control amount from the deviation between the suction-side measured pressure PL and the set pressure. At this time, the set pressure may be a lower limit value of the suction side pressure of the compressor. When the suction-side measured pressure PL is smaller than the lower limit value, the compressor controller 168 may calculate the command control amount from a deviation from the suction-side measured pressure PL. The lower limit value may be set empirically or experimentally as appropriate based on, for example, the minimum suction pressure of the compressor that ensures the exhaust capacity of the cryopump 10.

This can suppress an excessive temperature rise of the compressor main body due to a decrease in the flow rate of the working gas accompanying a decrease in the suction pressure. Further, when gas leakage occurs from the piping system of the working gas, excessive pressure drop can be prevented without immediately stopping the operation, and the operation can be continued for a certain period of time. Thus, the control of the suction pressure is an example of the protection control for the compressor unit.

Fig. 6 is a diagram schematically illustrating an output assignment table 181 according to an embodiment of the present invention. The vertical axis represents the 1 st output command value D1 (solid line) and the 2 nd output command value D2 (broken line), and the horizontal axis represents the command control amount D. The 1 st output command value D1 is shown by a solid line and the 2 nd output command value D2 is shown by a dashed line. As described above, the 1 st output command value D1 and the 2 nd output command value D2 correspond to or are related to the operating frequency command value and the opening degree command value, respectively, and the command control amount D corresponds to or is related to the target flow rate of the compressor unit. Thus, 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 relief valve 162 and the target flow rate of the compressor unit.

The range of values that can be used for the 1 st output command value D1 is limited to the 1 st interval and the 2 nd interval in advance. The 1 st interval is a range from the lower limit value D1L to the 1 st value D11, and the 2 nd interval is a range from the 2 nd value D12 to the upper limit value D1U. Since 1 st output command value D1 and operating frequency command value Seki are used, illustrated lower limit value D1L, 1 st value D11, 2 nd value D12, and upper limit value D1U correspond to the lower limit value, 1 st value, 2 nd value, and upper limit value of the operating frequency, respectively.

Thus, the range of values that can be used for the operating frequency is limited in advance to the 1 st operating frequency interval from the lower limit value to the 1 st value and the 2 nd operating frequency interval from the 2 nd value to the upper limit value, according to the output distribution table 181. The lower limit of the operating frequency is greater than zero, for example between 20Hz and 40Hz, or between 25Hz and 35Hz, for example 30 Hz. The upper limit of the operating frequency is, for example, between 70Hz and 90Hz, or between 75Hz and 85Hz, and may be, for example, 78 Hz. The upper limit and the lower limit of the operating frequency are determined in advance as specifications of the compressor, for example.

The interval of the 1 st value D11 to the 2 nd value D12 is not used. The unused frequency section corresponding to the 1 st to 2 nd values of the operating frequency of this section is determined to include at least one natural frequency ω 0 with respect to at least a part of the compressor structure portion 136 (for example, pipes such as the low pressure pipe 142, the high pressure pipe 144, and the bypass pipe 158). The 1 st and 2 nd values of the operating frequency are between the lower limit value and the upper limit value, and the 2 nd value is greater than the 1 st value. The natural frequency ω 0 is known from an empirical finding, an experiment, or a simulation test by a designer. The 1 st value is determined to be a value smaller than the natural frequency ω 0, and the 2 nd value is determined to be a value larger than the natural frequency ω 0.

The 1 st value D1, the 2 nd value D2, the 3 rd value D3 and the 4 th value D4 of the instruction controlled variable D in the output distribution table 181 are associated with the lower limit value D1L, the 1 st value D11, the 2 nd value D12 and the upper limit value D1U of the 1 st output instruction value D1. The thus specified set of the command control amount D and the 1 st output command value D1 (i.e., (D1, D1L), (D2, D11), (D3, D12), (D4, D1U)) are correlated with each other by linear interpolation to determine the relationship between the command control amount D and the 1 st output command value D1.

As shown in FIG. 6, in the case where the command control amount D is between the minimum value D0 and the 1 st value D1, the 1 st output command value D1 takes the lower limit value D1L. When the command controlled variable D is between the 1 st value D1 and the 2 nd value D2, the 1 st output command value D1 is between the lower limit value D1L and the 1 st value D11, and the 1 st output command value D1 and the command controlled variable D are in a linear or proportional relationship. In the case where the command control amount D is between the 2 nd value D2 and the 3 rd value D3, the 1 st output command value D1 takes the 2 nd value D12. In the case where the command controlled variable D is between the 3 rd value D3 and the 4 th value D4, the 1 st output command value D1 is between the 2 nd value D12 and the upper limit value D1U, and the 1 st output command value D1 is in a linear or proportional relationship with the command controlled variable D.

In accordance with the relationship between the command control amount D and the 1 st output command value D1, the output distribution table 181 associates the lower limit discharge flow rate, the 1 st discharge flow rate, the 2 nd discharge flow rate, and the upper limit discharge flow rate of the compressor body 140 with the lower limit value, the 1 st value, the 2 nd value, and the upper limit value of the operating frequency. When the target flow rate of the compressor unit is smaller than the lower limit discharge flow rate, the operating frequency is fixed to the lower limit value. When the target flow rate increases from the lower limit discharge flow rate to the 1 st discharge flow rate, the operating frequency linearly increases from the lower limit value to the 1 st value. If the target flow rate reaches the 1 st discharge flow rate, the operation frequency is switched from the 1 st value to the 2 nd value and is discontinuously increased. When the target flow rate increases from the 1 st discharge flow rate to the 2 nd discharge flow rate, the operating frequency is fixed to the 2 nd value. When the target discharge flow rate increases from the 2 nd discharge flow rate to the upper limit value, the operating frequency linearly increases from the 2 nd value to the upper limit value. When the target flow rate is reduced, the operating frequency is changed in a reverse manner.

In the output allocation table 181, the minimum value D0, the 1 st value D1, the 2 nd value D2, the 3 rd value D3, and the 4 th value D4 of the command controlled variable D are associated with the maximum value D22, the minimum value D20, the intermediate value D21, the minimum value D20, and the minimum value D20 of the 2 nd output command value D2. The maximum value D22 of the 2 nd output command value D2 may correspond to the maximum opening degree of the relief valve 162. The minimum value D20 of the 2 nd output command value D2 may correspond to the closing of the relief valve 162. The middle value D21 of the 2 nd output command value D2 may correspond to a certain middle opening degree of the relief valve 162. The relationship of the command control amount D and the 2 nd output command value D2 is determined by linear interpolation between the groups of the command control amount D and the 2 nd output command value D2.

As shown in fig. 6, in the case where the command control amount D is between the minimum value D0 and the 1 st value D1, the 2 nd output command value D2 is between the maximum value D22 and the minimum value D20, and the 2 nd output command value D2 is in a linear or proportional relationship with the command control amount D. In the case where the command control amount D is between the 1 st value D1 and the 2 nd value D2, the 2 nd output command value D2 takes the minimum value D20. In the case where the command control amount D is between the 2 nd value D2 and the 3 rd value D3, the 2 nd output command value D2 is between the intermediate value D21 and the minimum value D20, and the 2 nd output command value D2 is in a linear or proportional relationship with the command control amount D. In the case where the command control amount D is between the 3 rd value D3 and the 4 th value D4, the 2 nd output command value D2 takes the minimum value D20.

Based on the relationship between the command control amount D and the 2 nd output command value D2, the output distribution table 181 associates the discharge flow rate of the compressor main body 140 with the opening degree of the relief valve 162 (i.e., the flow rate of the bypass pipe 158). The relief valve 162 is set to the maximum opening degree when the target flow rate of the compressor unit is zero, and the opening degree of the relief valve 162 gradually decreases as the target flow rate increases from zero to the lower limit discharge flow rate. When the target flow rate increases from the lower limit discharge flow rate to the 1 st discharge flow rate, the relief valve 162 is closed. When the target flow rate reaches the 1 st discharge flow rate, the relief valve 162 is opened at the intermediate opening degree. When the target flow rate increases from the 1 st discharge flow rate to the 2 nd discharge flow rate, the opening degree of the relief valve 162 gradually decreases. When the target flow rate increases from the 2 nd discharge flow rate to the upper limit value, the relief valve 162 is closed. When the target flow rate decreases, the opening degree changes in a reverse manner.

By referring to such an output distribution table 181, in the case where the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate, the compressor controller 168 determines the inverter command signal E in such a manner that the operation frequency takes the 2 nd value. At the same time, the compressor controller 168 determines the relief valve command signal R so that the flow rate of the bypass pipe 158 matches the differential flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body 140 obtained from the inverter command signal.

According to the compressor unit of the embodiment, the unused section of the operating frequency is determined so as to include the natural frequency ω 0 of the compressor structure 136, and therefore resonance of the compressor structure 136 due to the operation of the compressor main body 140 is less likely to occur. Since the inverter command signal E is determined so that the operating frequency takes the 2 nd value, the working gas is discharged from the compressor body 140 to the high-pressure pipe 144 at the total flow rate that is the sum of the target flow rate and the surplus flow rate (corresponding to the differential flow rate). Since the relief valve command signal R is determined so that the flow rate of the bypass pipe 158 corresponds to the surplus flow rate thereof, the working gas is recovered from the high-pressure pipe 144 to the low-pressure pipe 142 at the surplus flow rate. Thereby, the

compressor units

102 and 104 can supply the working gas to the refrigerator 12 at a target flow rate. The resonance that may occur in the compressor unit driven by the inverter for the ultra-low temperature refrigerator can be prevented or alleviated without structural design changes, and a required discharge flow rate can be ensured.

In addition, in the case where the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate, the inverter command signal E may be determined so that the operating frequency is set in the 2 nd operating frequency section, instead of fixing the operating frequency to the 2 nd value. At this time, the operation frequency takes a value greater than the 2 nd value, and thus the discharge flow rate of the compressor main body 140 increases. The surplus flow rate can be offset by increasing the opening degree of the relief valve 162 and increasing the flow rate of the bypass pipe 158. However, since the operating frequency is small and the power consumption can be reduced, it is preferable to set the operating frequency to the 2 nd value as described above.

And, by referring to the output distribution table 181, in the case where the target flow rate is between the lower limit discharge flow rate and the 1 st discharge flow rate, the compressor controller 168 determines the inverter command signal E so that the operation frequency is set in the 1 st operation frequency section. At the same time, the compressor controller 168 determines the relief valve command signal R to cause the relief valve 162 to close. At this time, the discharge flow rate of the compressor unit is controlled only by the compressor inverter 170. The relief valve 162 is not used in the discharge flow control.

In the case where the target flow rate is between the 2 nd discharge flow rate and the upper limit discharge flow rate, the compressor controller 168 determines the inverter command signal E so that the operating frequency is set in the 2 nd operating frequency interval. At the same time, the compressor controller 168 determines the relief valve command signal R to cause the relief valve 162 to close. At this time, the discharge flow rate of the compressor unit is controlled only by the compressor inverter 170. The relief valve 162 is not used in the discharge flow control.

In the case where the target flow rate is between zero and the lower limit discharge flow rate, the compressor controller 168 determines the inverter command signal E so that the operating frequency takes the lower limit value. At the same time, the compressor controller 168 determines the relief valve command signal R so that the flow rate of the bypass pipe 158 matches the differential flow rate. At this time, the discharge flow rate of the compressor unit is controlled only by the relief valve 162.

When the operating frequency is switched from the 1 st value to the 2 nd value, the compressor controller may perform smoothing processing on the relief valve command signal R and/or the inverter command signal E. The smoothing process may be a time smoothing process such as a low-pass filter or an average shift, or any other known smoothing process. This can prevent or mitigate adverse effects on the helium gas flow rate due to discontinuous changes in the relief valve command signal R and/or the inverter command signal E.

The present invention has been described above with reference to the embodiments. The present invention is not limited to the above-described embodiments, and various design changes and various modifications can be made, and such modifications also fall within the scope of the present invention, which will be apparent to those skilled in the art.

In one embodiment, the CP controller 100 may control the

compressor units

102, 104. The CP controller 100 may be provided with a compressor controller 168. The CP controller 100 may be provided with a compressor inverter 170. The CP controller 100 may include at least one of a safety valve driver 174, a control amount calculation unit 176, a deviation calculation unit 178, an output distribution processing unit 180, an output distribution table 181, an inverter command unit 182, and a safety valve command unit 184.

Description of the symbols

12-refrigerator, 136-compressor structure, 140-compressor body, 142-low pressure piping, 144-high pressure piping, 158-bypass piping, 168-compressor controller, 170-compressor inverter, 172-compressor motor

Industrial applicability

The present invention is applicable to a compressor unit and a cryopump system for an ultra-low temperature refrigerator.

Claims

1. A compressor unit for an ultra-low-temperature refrigerator, comprising:

a compressor structure, comprising: a compressor main body that compresses and discharges working gas of the ultra-low-temperature refrigerator; a compressor motor that operates the compressor main body while varying an operating frequency thereof; a high-pressure pipe connected to the compressor main body to discharge working gas from the compressor main body; a low-pressure pipe connected to the compressor main body to suck a working gas into the compressor main body; a bypass pipe that bypasses the compressor main body and connects the high-pressure pipe to the low-pressure pipe; and a flow control valve provided in the bypass pipe to control a flow rate of the bypass pipe in accordance with a valve command signal;

a compressor inverter controlling the operating frequency of the compressor motor according to an inverter command signal; and

a compressor controller configured to determine the valve command signal and the inverter command signal so that the working gas is supplied from the compressor unit to the ultra-low-temperature refrigerator at a target flow rate,

the range of values that the operating frequency can take is defined in advance in a 1 st operating frequency section from a lower limit value to a 1 st value that is greater than zero, and a 2 nd operating frequency section from a 2 nd value to an upper limit value, the 2 nd value being greater than the 1 st value, and the 1 st value and the 2 nd value being determined such that the non-use frequency section from the 1 st value to the 2 nd value includes at least one natural frequency with respect to at least a part of the compressor structural portion, the lower limit value, the 1 st value, the 2 nd value, and the upper limit value of the operating frequency respectively corresponding to a lower limit discharge flow rate, a 1 st discharge flow rate, a 2 nd discharge flow rate, and an upper limit discharge flow rate of the compressor main body,

the compressor controller performs smoothing processing on the valve command signal and/or the inverter command signal when the operating frequency is switched from the 1 st value to the 2 nd value,

when the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate, the compressor controller determines the inverter command signal so that the operating frequency is set in the 2 nd operating frequency range, and determines the valve command signal so that the flow rate of the bypass pipe matches a differential flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body obtained from the inverter command signal.

2. Compressor unit according to claim 1,

the compressor controller determines the inverter command signal so that the operating frequency takes the 2 nd value in a case where the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate.

3. Compressor unit according to claim 1 or 2,

the compressor controller determines the inverter command signal so that the operation frequency is set in the 1 st operation frequency section and determines the valve command signal so that the flow control valve is closed in a case where the target flow rate is between the lower limit discharge flow rate and the 1 st discharge flow rate,

in the case where the target flow rate is between the 2 nd discharge flow rate and the upper limit discharge flow rate, the compressor controller determines the inverter command signal so that the operating frequency is set in the 2 nd operating frequency interval, and determines the valve command signal so that the flow control valve is closed.

4. Compressor unit according to claim 1 or 2,

when the target flow rate is between zero and the lower limit discharge flow rate, the compressor controller determines the inverter command signal so that the operating frequency assumes the lower limit value, and determines the valve command signal so that the flow rate of the bypass pipe coincides with the differential flow rate.

5. A cryopump system includes:

a cryopump including a cryopanel and a cryogenic refrigerator for cooling the cryopanel;

a compressor unit including a compressor structure, the compressor structure including: a compressor main body that compresses and discharges working gas of the ultra-low-temperature refrigerator; a compressor motor that operates the compressor main body while varying an operating frequency thereof; a high-pressure pipe connected to the compressor main body to discharge working gas from the compressor main body; a low-pressure pipe connected to the compressor main body to suck a working gas into the compressor main body; a bypass pipe that bypasses the compressor main body and connects the high-pressure pipe to the low-pressure pipe; and a flow control valve provided in the bypass pipe to control a flow rate of the bypass pipe in accordance with a valve command signal;

a controller configured to determine the valve command signal and the inverter command signal so that the working gas is supplied from the compressor unit to the ultra-low-temperature refrigerator at a target flow rate,

the range of values that the operating frequency can take is defined in advance as a 1 st operating frequency section from a lower limit value to a 1 st value that is greater than zero, and a 2 nd operating frequency section from a 2 nd value to an upper limit value, the 2 nd value is greater than the 1 st value, the 1 st value and the 2 nd value are determined such that the non-use frequency section from the 1 st value to the 2 nd value includes at least one natural frequency with respect to at least a part of the compressor structural portion, the lower limit value, the 1 st value, the 2 nd value, and the upper limit value of the operating frequency correspond to a lower limit discharge flow rate, a 1 st discharge flow rate, a 2 nd discharge flow rate, and an upper limit discharge flow rate of the compressor main body, respectively,

the controller performs smoothing processing on the valve command signal and/or the inverter command signal when the operating frequency is switched from the 1 st value to the 2 nd value,

when the target flow rate is between the 1 st discharge flow rate and the 2 nd discharge flow rate, the controller determines the inverter command signal so that the operating frequency is set in the 2 nd operating frequency range, and determines the valve command signal so that the flow rate of the bypass pipe matches a differential flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body obtained from the inverter command signal.