KR20190116263A - Compressor units and cryopump systems for cryogenic chillers - Google Patents

Abstract

The compressor unit includes a flow control valve for controlling the flow rate of the bypass pipe in accordance with the valve command signal, the compressor inverter 170, and the compressor controller 168. The range of values that the driving frequency can take is limited in advance to the first operating frequency section from the lower limit value to the first value and the second operating frequency section from the second value to the upper limit value, and to the first value to the second value. The unused frequency range includes the natural frequency of the compressor structure. When the target flow rate is between the first discharge flow rate and the second discharge flow rate, the compressor controller 168 determines the inverter command signal so that the operation frequency is set to the second operation frequency section, and is obtained according to the inverter command signal. The valve command signal is determined so that the flow rate of the bypass pipe coincides with the differential flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body.

Description

Compressor units and cryopump systems for cryogenic chillers

The present invention relates to a compressor unit for a cryogenic refrigerator, and a cryopump system.

Background Art Conventionally, in a so-called inverter compressor in which an inverter is mounted and the operating frequency is variable, a vibration suppressing technique for changing the operating frequency of the compressor when the detection output of the vibration sensor is large is known.

Patent Document 1: Japanese Patent Application Laid-Open No. 2001-317470

One exemplary object of one aspect of the present invention is to provide a simple method of coping with vibration for a compressor unit of an inverter drive for a cryogenic refrigerator.

According to one aspect of the present invention, a compressor unit for a cryogenic refrigerator is provided. The compressor unit includes a compressor main body for compressing and discharging the working gas of a cryogenic refrigerator, a compressor motor for operating the compressor main body with a variable operating frequency, a high pressure pipe connected to the compressor main body to discharge working gas from the compressor main body, and a compressor. The low pressure pipe connected to the compressor main body to suck the working gas into the main body, the bypass pipe connecting the high pressure pipe to the low pressure pipe bypassing the compressor main body, and the bypass pipe to control the flow rate of the bypass pipe according to the valve command signal. Compressor structure including a flow control valve provided in the compressor, a compressor inverter for controlling the operating frequency of the compressor motor in accordance with the inverter command signal, the valve command signal and the inverter command signal to supply the working gas from the compressor unit to the cryogenic freezer at the target flow rate And a compressor controller configured to determine. The range of values that the driving frequency can take is limited in advance to the first operating frequency section from the lower limit value greater than zero to the first value, and the second operating frequency section from the second value to the upper limit value. Greater than 1 The first value and the second value are defined such that the unused frequency interval from the first value to the second value includes at least one natural frequency for at least a portion of the compressor structure. The lower limit value, the first value, the second value, and the upper limit value of the operating frequency correspond to the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge flow rate of the compressor main body, respectively. When the target flow rate is between the first discharge flow rate and the second discharge flow rate, the compressor controller determines the inverter command signal so that the operation frequency is set to the second operation frequency section, and the compressor obtained according to the inverter command signal. The valve command signal is determined so that the flow rate of the bypass pipe matches the difference flow rate obtained by subtracting the target flow rate from the discharge flow rate of the main body.

According to an aspect of the present invention, a cryopump system includes a cryopump including a cryopanel, a cryogenic chiller for cooling the cryopanel, and a compressor body for compressing and discharging the working gas of the cryogenic chiller. And a compressor motor for operating the compressor main body having a variable operating frequency, a high pressure pipe connected to the compressor main body to discharge working gas from the compressor main body, and a connection to the compressor main body to suck working gas into the compressor main body. A low pressure pipe, a bypass pipe for bypassing the compressor main body to connect the high pressure pipe to the low pressure pipe, and a flow control valve provided in the bypass pipe to control the flow rate of the bypass pipe according to a valve command signal. A compressor unit having a compressor structure including a compressor unit, and the compressor unit according to an inverter command signal. Of and a controller configured to determine the valve command signal and the drive instruction signal and an inverter compressor for controlling the operating frequency, the operating gas in the cryogenic freezer from the compressor unit is to be supplied to the target flow rate. The range of values that the driving frequency can take is limited in advance to the first operating frequency section from the lower limit value greater than zero to the first value, and the second operating frequency section from the second value to the upper limit value. Greater than 1 The first value and the second value are defined such that the unused frequency interval from the first value to the second value includes at least one natural frequency for at least a portion of the compressor structure. The lower limit value, the first value, the second value, and the upper limit value of the operating frequency correspond to the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge flow rate of the compressor main body, respectively. When the target flow rate is between the first discharge flow rate and the second discharge flow rate, the controller determines the inverter command signal so that the operation frequency is set to the second operation frequency section, and the compressor main body obtained according to the inverter command signal. The valve command signal is determined so that the flow rate of the bypass pipe coincides with the difference flow rate obtained by subtracting the target flow rate from the discharge flow rate.

However, any combination of the above components, or the components or representations of the present invention are replaced with each other between methods, apparatuses, systems and the like is also effective as an aspect of the present invention.

According to the present invention, a simple method of coping with vibration can be provided for the compressor unit of the inverter driving for the cryogenic refrigerator.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the whole structure of the cryopump system concerning one Embodiment of this invention.
2 is a cross-sectional view schematically showing a cryopump according to an embodiment of the present invention.
3 is a diagram schematically showing a compressor unit according to an embodiment of the present invention.
4 is a control block diagram of a cryopump system according to the present embodiment.
5 is a view for explaining a control flow of the compressor unit operation control according to the embodiment of the present invention.
6 is a diagram schematically illustrating an output distribution table according to one embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail, referring drawings. In addition, in description, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted suitably. In addition, the structure demonstrated below is an illustration and does not limit the scope of the present invention. In addition, in the drawing referred to in the following description, the size and thickness of each structural member are for convenience of description, and do not necessarily show actual dimension or ratio.

Cryogenic systems are known that have a cryogenic freezer and a compressor unit for supplying a working gas to the freezer. As an example of a cryogenic system, a system including a cryogenic device (for example, a cryopump) having a cryogenic chiller as a cooling source is also known. In the cryogenic system, the operating frequency of the compressor unit is controlled by using the pressure target value and the pressure measurement value, for example, to match the differential pressure between the high pressure side and the low pressure side of the working gas of the refrigerator to the set value. have. This control contributes to reducing the power consumption of the system, since the target operating gas flow required for the refrigerator can be provided at the optimum (minimum) operating frequency.

It is assumed that the operating frequency range used for the inverter includes the natural frequency of the mechanical structure such as the piping of the compressor unit. The compressor unit during operation becomes a source of excitation itself. When the value of the operating frequency approaches the natural frequency, resonance may occur in the mechanical structure of the compressor unit. Excessive vibration, noise, or fatigue of the structural members are undesirable.

To avoid this problem, it is prohibited to take the operating frequency close to the natural frequency. However, this means that when the value of the optimum operating frequency is close to the natural frequency, the value away from the natural frequency is used instead of the value. When the operating frequency is changed to a smaller value, there is a fear that the supply flow rate from the compressor unit may be insufficient for the operating gas flow rate required for the refrigerator. In the case of changing the operating frequency to a larger value, the power consumption of the compressor unit increases, leading to inadequate results in which the advantage of power consumption reduction of the inverter control is not sufficiently obtained.

As a fundamental solution, it is also conceivable to change the design of the compressor unit so that the natural frequency of the mechanical structure is not included in the operating frequency range used. However, such a design change takes time.

According to one aspect of the present invention, a compressor unit for a cryogenic refrigerator is provided. The compressor unit includes a compressor main body for compressing and discharging the working gas of a cryogenic refrigerator, a compressor motor for operating the compressor main body with a variable operating frequency, a high pressure pipe connected to the compressor main body to discharge working gas from the compressor main body, and a compressor. The low pressure pipe connected to the compressor main body to suck the working gas into the main body, the bypass pipe connecting the high pressure pipe to the low pressure pipe bypassing the compressor main body, and the bypass pipe to control the flow rate of the bypass pipe according to the valve command signal. Compressor structure including a flow control valve provided in the compressor, a compressor inverter for controlling the operating frequency of the compressor motor in accordance with the inverter command signal, the valve command signal and the inverter command signal to supply the working gas from the compressor unit to the cryogenic freezer at the target flow rate And a compressor controller configured to determine. The range of values that the driving frequency can take is limited in advance to the first operating frequency section from the lower limit value greater than zero to the first value, and the second operating frequency section from the second value to the upper limit value. Greater than 1 The first value and the second value are defined such that the unused frequency interval from the first value to the second value includes at least one natural frequency for at least a portion of the compressor structure. The lower limit value, the first value, the second value, and the upper limit value of the operating frequency correspond to the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge flow rate of the compressor main body, respectively. When the target flow rate is between the first discharge flow rate and the second discharge flow rate, the compressor controller determines the inverter command signal so that the operation frequency is set to the second operation frequency section, and the compressor obtained according to the inverter command signal. The valve command signal is determined so that the flow rate of the bypass pipe matches the difference flow rate obtained by subtracting the target flow rate from the discharge flow rate of the main body.

According to this aspect, since the unused section of the operating frequency is determined to include the natural frequency of the compressor structure part, resonance of the compressor structure part due to the operation of the compressor main body is unlikely to occur. Further, since the inverter command signal is determined so that the operating frequency is set in the second operating frequency section, the working gas is discharged from the compressor main body to the high pressure pipe at the total flow rate in which the excess flow rate (the difference flow rate above) is added to the target flow rate. Since the valve command signal is determined so that the excess flow rate corresponds to the flow rate of the bypass pipe, 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 cryogenic freezer at the target flow rate.

The compressor controller may determine the inverter command signal so that the operating frequency takes the second value when the target flow rate is between the first discharge flow rate and the second discharge flow rate.

When the target flow rate is between the lower limit discharge flow rate and the first discharge flow rate, the compressor controller determines the inverter command signal so that the operation frequency is set to the first operation frequency section, and the valve command signal so that the flow control valve is closed. May be determined. The compressor controller determines the inverter command signal so that the operating frequency is set to the second operating frequency section when the target flow rate is between the second discharge flow rate and the upper limit discharge flow rate, and the valve command signal so that the flow control valve is closed. May be determined.

The compressor controller determines the inverter command signal so that the operating frequency takes the lower limit when the target flow rate is between zero and the lower limit discharge flow rate, and determines the valve command signal so that the flow rate of the bypass pipe matches the differential flow rate. You may also

The compressor controller may perform a smoothing process with the valve command signal and / or the inverter command signal when the operation frequency is switched from the first value to the second value.

FIG. 1: is a figure which shows typically the whole structure of the cryopump system 1000 which concerns on one Embodiment of this invention. The cryopump system 1000 is used for evacuating the vacuum apparatus 300. The vacuum apparatus 300 is a vacuum processing apparatus for processing an object in a vacuum environment, and is used in, for example, a semiconductor manufacturing process such as an ion implantation apparatus or a sputtering apparatus.

The cryopump system 1000 includes a plurality of cryopumps 10. These cryopumps 10 are mounted in one or a plurality of vacuum chambers (not shown) of the vacuum apparatus 300 and are used to raise the degree of vacuum inside the vacuum chamber to a level required by a desired process. The cryopump 10 is operated according to the control amount determined by the cryopump controller (hereinafter also referred to as CP controller) 100. For example, a high degree of vacuum of about 10 ⁻⁵ Pa to 10 ⁻⁸ Pa is realized in the vacuum chamber. In the example shown in the figure, 11 cryopumps 10 are included in the cryopump system 1000. The plurality of cryopumps 10 may all be cryopumps having the same exhaust performance, or may be cryopumps having different exhaust performance.

The cryopump system 1000 includes a CP controller 100. The CP controller 100 controls the cryopump 10 and the compressor units 102 and 104. The CP controller 100 includes a CPU which executes various arithmetic processes, a ROM which stores various control programs, a RAM used as a work area for data storage and program execution, an input / output interface, a memory, and the like. The CP controller 100 is also configured to be capable of communicating with a host controller (not shown) for controlling the vacuum apparatus 300. The host controller of the vacuum apparatus 300 may also be referred to as a higher controller that integrates each component of the vacuum apparatus 300 including the cryopump system 1000.

The CP controller 100 is constituted 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 communicate with each other. The cryopump 10 has an IO module 50 (see FIG. 4) for processing input and output communicating with the CP controller 100, respectively. The CP controller 100 and each IO module 50 are connected by a control communication line. In FIG. 1, the control communication line between the cryopump 10 and the CP controller 100 and the control communication line between the compressor units 102 and 104 and the CP controller 100 are indicated by broken lines. However, the CP controller 100 may be integrated with any one of the cryopumps 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 showing the same or different functions. For example, the CP controller 100 may be provided in each compressor unit, and may be provided with the compressor controller which determines the control amount of each compressor unit, and the cryopump controller which integrates a cryopump system.

The cryopump system 1000 includes a plurality of compressor units including at least a first compressor unit 102 and a second compressor unit 104. The compressor unit is provided for circulating the working gas in a closed fluid circuit including the cryopump 10. The compressor unit recovers the working gas from the cryopump 10, compresses it, and sends the compressed gas back to the cryopump 10. The compressor unit is separated from the vacuum apparatus 300 or is installed in the vicinity of the vacuum apparatus 300. The compressor unit is operated according to the control amount determined by the compressor controller 168 (see Fig. 4). Or the CP controller 100 is operated according to the control amount determined.

Hereinafter, the cryopump system 1000 having two compressor units 102 and 104 will be described as a representative example. However, the present invention is not limited thereto. In the same manner as the compressor units 102 and 104, the cryopump system 1000 may be configured in which three or more compressor units are connected in parallel to the plurality of cryopumps 10. However, although the cryopump system 1000 shown in FIG. 1 is equipped with the cryopump 10 and the compressor units 102 and 104, respectively, the cryopump 10 or the compressor units 102 and 104 are 1st. You can do as you please.

The plurality of cryopumps 10 and the plurality of compressor units 102, 104 are connected by the working gas piping 106. The piping system 106 connects the plurality of cryopumps 10 and the plurality of compressor units 102 and 104 in parallel to each other, and the plurality of cryopumps 10 and the plurality of compressor units 102 and 104 are connected. It is configured to distribute the working gas between. By the piping system 106, each of the plurality of compressor units is connected in parallel to one cryopump 10, and each of the plurality of cryopumps 10 is connected in parallel to one compressor unit.

The piping system 106 includes an inner piping 108 and an outer 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 installed outside the vacuum apparatus 300 and includes an external supply line 120 and an external return line 122. The external pipe 110 connects the vacuum apparatus 300 and the plurality of compressor units 102 and 104.

The internal supply line 112 is connected to the gas supply port 42 of each cryopump 10 (see FIG. 2), and the internal return line 114 is the gas outlet 44 of each cryopump 10. It is connected to (refer FIG. 2). In addition, the internal supply line 112 is connected to one end of the external supply line 120 of the external pipe 110 from the gas supply port 116 of the vacuum device 300, the internal return line 114 is a vacuum device ( The gas discharge port 118 of 300 is connected to one end of the outer return line 122 of the outer pipe 110.

The other end of the external supply line 120 is connected to the first manifold 124, and the other end of the external return line 122 is connected to the second manifold 126. One end of the first discharge pipe 128 of the first compressor unit 102 and the second discharge pipe 130 of the second compressor unit 104 is connected to the first manifold 124. The other ends of the first discharge pipe 128 and the second discharge pipe 130 are connected to discharge ports 148 of the respective compressor units 102 and 104, respectively (see Fig. 3). One end of the first suction pipe 132 of the first compressor unit 102 and the second suction pipe 134 of the second compressor unit 104 is connected to the second manifold 126. The other ends of the first suction pipe 132 and the second suction pipe 134 are connected to suction ports 146 of the corresponding compressor units 102 and 104, respectively (see Fig. 3).

In this way, a common supply line for collecting and supplying the working gas sent from each of the plurality of compressor units 102 and 104 to the plurality of cryopumps 10 is the internal supply line 112 and the external supply line. It consists of 120. In addition, a common return line for collecting working gases discharged from the plurality of cryopumps 10 and returning them to the plurality of compressor units 102 and 104 is provided by the inner return line 114 and the outer return line 122. Consists of. In addition, each of the plurality of compressor units is connected to a common line through separate piping accompanying each compressor unit. Connections between individual pipes and common lines are provided with manifolds for joining the individual pipes. The first manifold 124 joins the individual pipes on the supply side, and the second manifold 126 joins the individual pipes on the recovery side.

Depending on the layout of the various devices in the place where the cryopump system 1000 is used (for example, a semiconductor manufacturing plant), the common line described above may be of considerable length (unlike shown). By condensing the working gases into a common line, the total piping length can be shortened as compared with the case where each of the plurality of compressors is separately connected to the vacuum apparatus. In addition, since a piping configuration is provided in which a plurality of compressors are connected to each target gas supply object (for example, in the cryopump system 1000, each cryopump 10), there is also redundancy. . By arranging and operating a plurality of compressors in parallel to individual objects (for example, cryopumps), the load on the plurality of compressors is shared.

2 is a cross-sectional view schematically showing a cryopump 10 according to an embodiment of the present invention. The cryopump 10 includes a first cryopanel cooled to a first cooling temperature level, and a second cryopanel cooled to a second cooling temperature level lower than the first cooling temperature level. In the first cryopanel, gas having a low vapor pressure at the first cooling temperature level is captured by the condensation and exhausted. For example, the gas whose vapor pressure is lower than the reference vapor pressure (for example, 10 ^-8 Pa) is exhausted. In the second cryopanel, gas having a low vapor pressure at the second cooling temperature level is captured by the condensation and exhausted. In the second cryopanel, since the vapor pressure is high, an adsorption region is formed on the surface to capture the non-condensable gas which does not condense even at the second temperature level. The adsorption region is formed by providing an adsorbent on the panel surface, for example. The non-condensable gas is adsorbed in the adsorption zone cooled to the second temperature level and exhausted.

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 thermal cycle in which the working gas is sucked, expanded and discharged therein. The panel structure 14 includes a plurality of cryopanels, which are cooled by the refrigerator 12. The surface of the panel is formed with a cryogenic surface for trapping and exhausting gas by condensation or adsorption. The surface (for example, the back surface) of the cryopanel is usually provided with an adsorbent such as activated carbon for adsorbing gas. The heat shield 16 is provided to protect the panel structure 14 from 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 arranged along the axial direction of the heat shield 16. However, the present invention can be equally applied to a so-called horizontal cryopump. The horizontal cryopump is a cryopump in which the second stage cooling stage of the refrigerator is inserted and arranged in a direction intersecting the axial direction of the heat shield 16 (usually orthogonal). 1, the horizontal cryopump 10 is shown typically.

The refrigerator 12 is a Gifford McMahon type refrigerator (so-called GM refrigerator). The refrigerator 12 is a two-stage refrigerator, and includes a first stage cylinder 18, a second stage cylinder 20, a first cooling stage 22, a second cooling stage 24, and a refrigerator motor 26. Has The first stage cylinder 18 and the second stage cylinder 20 are connected in series, and a first stage displacer and a second stage displacer (not shown) connected to each other are built in, respectively. An inside of the first stage displacer and the second stage displacer includes a quenching material. However, the refrigerator 12 may be a refrigerator other than a two stage GM refrigerator, for example, a single stage GM refrigerator may be used, and a pulse tube refrigerator or a Solvay refrigerator may be used.

The refrigerator 12 includes a flow path switching mechanism for periodically switching the flow path of the working gas in order 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 for driving the valve portion. The valve portion is, for example, a rotary valve, and the driving portion is a motor for rotating the rotary valve. The motor may be, for example, an AC motor or a DC motor. The flow path switching mechanism may be a linear mechanism driven by a linear motor.

One end of the first stage cylinder 18 is provided with a refrigerator motor 26. The refrigerator motor 26 is provided inside the motor housing 27 formed at the end of the first stage cylinder 18. The refrigerator motor 26 includes a first stage displacer such that each of the first stage displacer and the second stage displacer allows the inside of the first stage cylinder 18 and the second stage cylinder 20 to be reciprocated. It is connected to the second stage displacer. In addition, the refrigerator motor 26 is connected to the valve so that the movable valve (not shown) provided in the motor housing 27 can be rotated forward and backward.

The 1st cooling stage 22 is provided in the edge part by the side of the 2nd end cylinder 20 of the 1st end cylinder 18, ie, the connection part of the 1st end cylinder 18 and the 2nd end cylinder 20. As shown in FIG. In addition, the second cooling stage 24 is provided at the end of the second stage cylinder 20. The first cooling stage 22 and the second cooling stage 24 are fixed to the first stage cylinder 18 and the second stage cylinder 20 by brazing, for example.

The refrigerator 12 is connected to the compressor unit 102 or 104 via the gas supply port 42 and the gas discharge port 44 provided outside the motor housing 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 internally the high-pressure working gas supplied from the compressor units 102 and 104 (for example, helium) to cool the first cooling stage 22 and the second cooling stage 24. Generate. The compressor units 102 and 104 recover the working gas expanded in the refrigerator 12, pressurize it again, and supply the same to the refrigerator 12.

Specifically, a high-pressure working gas is first 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 gas 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 a high-pressure working gas, the movable valve is switched by the refrigerator motor 26 so that the internal space of the refrigerator 12 communicates with the gas outlet 44. As a result, the working gas is expanded and recovered to the compressor units 102 and 104. In synchronization with the operation of the movable valve, each of the first stage displacer and the second stage displacer reciprocates the inside of the first stage cylinder 18 and the second stage cylinder 20. By repeating such a thermal cycle, the refrigerator 12 generates cold in the first cooling stage 22 and the second cooling stage 24.

The second cooling stage 24 is cooled to a lower temperature than the first cooling stage 22. The second cooling stage 24 is cooled, for example, about 10K to 20K, and the first cooling stage 22 is cooled, for example, about 80K to 100K. The first cooling stage 22 is equipped with a first temperature sensor 23 for measuring the temperature of the first cooling stage 22, and the second cooling stage 24 is equipped with a temperature of the second cooling stage 24. The second temperature sensor 25 for measuring the temperature is mounted.

The heat shield 16 is fixed to the first cooling stage 22 of the refrigerator 12 in a thermally connected state, and the panel structure 14 is thermally connected to the second cooling stage 24 of the refrigerator 12. It is fixed in the closed state. As a result, the heat shield 16 is cooled to the same temperature as the first cooling stage 22, and the panel structure 14 is cooled to the same temperature as the second cooling stage 24. The heat shield 16 is formed in the cylindrical shape which has the opening part 31 at one end. The opening 31 is defined by the end inner surface of the normal side surface of the heat shield 16.

On the other hand, the blocking part 28 is formed in the other end of the heat shield 16 on the opposite side to the opening part 31, the pump bottom part side. The closure portion 28 is formed by a flange portion extending toward the inner side in the radial direction at the end portion of the pump bottom portion side of the cylindrical side surface of the heat shield 16. Since the cryopump 10 shown in FIG. 2 is a vertical cryopump, this flange part is attached to the 1st cooling stage 22 of the refrigerator 12. As a result, a cylindrical inner space 30 is formed inside the heat shield 16. The refrigerator 12 protrudes into the inner space 30 along the central axis of the heat shield 16, and the second cooling stage 24 is inserted into the inner space 30.

However, in the case of a horizontal cryopump, the occlusion part 28 is normally completely occluded. The refrigerator 12 protrudes from the freezer mounting opening formed in the side surface of the heat shield 16 in the inner space 30 along the direction orthogonal to the central axis of the heat shield 16. The first cooling stage 22 of the refrigerator 12 is mounted in the freezer mounting opening of the heat shield 16, and the second cooling stage 24 of the refrigerator 12 is disposed in the internal space 30. The panel structure 14 is mounted to the second cooling stage 24. Thus, the panel structure 14 is disposed in the interior space 30 of the heat shield 16. The panel structure 14 may be attached to the second cooling stage 24 via a panel mounting member of a suitable shape.

In addition, a baffle 32 is provided in the opening 31 of the heat shield 16. The baffle 32 is provided with the panel structure 14 at intervals in the central axis direction of the heat shield 16. The baffle 32 is attached to an end portion of the heat shield 16 on the opening 31 side, and is cooled to the same temperature as the heat shield 16. The baffle 32 may be formed concentrically, for example when viewed from the vacuum chamber 80 side, or may be formed in other shapes, such as a lattice form. However, 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, for example, and is opened when the vacuum chamber 80 is exhausted by the cryopump 10. The vacuum chamber 80 is provided in the vacuum apparatus 300 shown in FIG. 1, for example.

The heat shield 16, the baffle 32, the panel structure 14, and the first cooling stage 22 and the second cooling stage 24 of the refrigerator 12 are accommodated in the pump case 34. have. The pump case 34 is formed by connecting two cylinders of different diameters in series. The large cylindrical side end of the pump case 34 is opened, and the flange part 36 for connection with the vacuum chamber 80 extends radially outward. Moreover, the cylindrical side end of the small diameter of the pump case 34 is being fixed to the motor housing 27 of the refrigerator 12. As shown in FIG. The cryopump 10 is hermetically fixed to the exhaust opening of the vacuum chamber 80 through the flange portion 36 of the pump case 34, and is integral with the internal space of the vacuum chamber 80. An airtight space is formed. The pump case 34 and the heat shield 16 are both formed in a cylindrical shape and are arranged coaxially. Since the inner diameter of the pump case 34 slightly exceeds the outer diameter of the heat shield 16, the heat shield 16 is disposed with a slight gap between the inner surface of the pump case 34 and the inner diameter of the pump case 34.

In the operation of the cryopump 10, first, roughly pump the inside of the vacuum chamber 80 to about 1 Pa to about 10 Pa using another suitable rough pump before the operation. The cryopump 10 is then operated. The heat shield 16, the baffle 32, and the panel structure 14, in which the first cooling stage 22 and the second cooling stage 24 are cooled and thermally connected thereto by the operation of the refrigerator 12. It is also cooled.

The cooled baffle 32 cools gas molecules that flow from the vacuum chamber 80 toward the cryopump 10, and at which the vapor pressure becomes sufficiently low at the cooling temperature (for example, moisture). Etc.) on the surface and exhausted. At a cooling temperature of the baffle 32, a gas whose vapor pressure is not sufficiently lowered enters the heat shield 16 through the baffle 32. Among the gas molecules that have entered, a gas (for example, argon) whose vapor pressure is sufficiently lowered at the cooling temperature of the panel structure 14 is condensed on the surface of the panel structure 14 and exhausted. The gas (for example, hydrogen, etc.) whose vapor pressure does not become low enough even at the cooling temperature is adsorbed and exhausted by the adsorbent cooled by adhering to the surface of the panel structure 14. In this way, the cryopump 10 can reach the desired level of the degree of vacuum inside the vacuum chamber 80.

3 is a diagram schematically showing a first compressor unit 102 according to one embodiment of the present invention. In this embodiment, the second compressor unit 104 also has the same configuration as the first compressor unit 102. The compressor unit 102 includes a compressor main body 140 for boosting gas, a low pressure pipe 142 for supplying a low pressure gas supplied from the outside to the compressor main body 140, and a high pressure compressed by the compressor main body 140. It is configured to include a high pressure pipe 144 for sending gas to the outside.

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

The low pressure pipe 142 is provided with a storage tank 150 as a volume for removing the pulsation contained in the return gas halfway. The storage tank 150 is provided between the suction port 146 and the branch to the bypass mechanism 152 described later. The working gas from which the pulsation is removed from the storage tank 150 is supplied to the compressor main body 140 through the low pressure pipe 142. A filter may be provided inside the storage tank 150 to remove unnecessary particulates from the gas. An introduction port and piping for replenishing working gas from the outside may be connected between the storage tank 150 and the suction port 146.

The compressor main body 140 is, for example, a scroll system or a rotary pump and exhibits a function of boosting the suctioned gas. The compressor main body 140 is provided with a compressor motor 172, and the compressor main body 140 is driven by the compressor motor 172. The compressor main body 140 sends the boosted working gas to the high pressure pipe 144. The compressor main body 140 is configured to cool by using oil, and an oil cooling pipe for circulating oil is provided to the compressor main body 140. For this reason, the boosted working gas is sent to the high pressure pipe 144 in a state in which the oil is slightly mixed.

Therefore, the oil separator 154 is provided in the high pressure piping 144 midway. The oil separated from the working gas in the oil separator 154 may be returned to the low pressure pipe 142 and may be returned to the compressor main body 140 through the low pressure pipe 142. The oil separator 154 may be provided with a relief valve for releasing excessive high pressure.

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

The working gas via the oil separator 154 is sent to the adsorber 156 through the high pressure pipe 144. The adsorber 156 is provided in order to remove the contaminant which is not removed by the contaminant removal means on the flow path, such as the filter in the storage tank 150, or the oil separator 154, from a working gas, for example. The adsorber 156 removes the vaporized oil component by adsorption, for example.

The discharge port 148 is provided in the compressor case body 138 of the first compressor unit 102 at the end of the high pressure pipe 144. That is, the high pressure pipe 144 connects the compressor main body 140 and the discharge port 148, and the oil separator 154 and the adsorber 156 are provided in the middle. The working gas via the adsorber 156 is sent to the cryopump 10 through the discharge port 148.

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

The bypass mechanism 152 is provided with a control valve for controlling the operating gas flow rate which is not sent to the cryopump 10 and bypasses the high pressure pipe 144 to the low pressure pipe 142. In the illustrated embodiment, a first control valve (also referred to as a pressure equalizing valve) 160 and a second control valve (also referred to as a relief valve) 162 are provided in the middle of the bypass pipe 158 in parallel. The equalization valve 160 is, for example, a solenoid valve of an open type. Therefore, when the operation of the first compressor unit 102 is stopped (that is, when the power supply to the first compressor unit 102 is stopped), the equalization valve 160 is opened to the low pressure pipe 142 and the high pressure pipe 144. The pressure is equal. The relief valve 162 is a normally closed solenoid valve, for example. In this embodiment, the relief valve 162 is used as the flow control valve of the bypass pipe 158 during the operation of the first compressor unit 102.

The first compressor unit 102 includes a first pressure sensor 164 for measuring the pressure of the return gas from the cryopump 10, and a pressure for sending gas to the cryopump 10. A second pressure sensor 166 is provided. During the operation of the first compressor unit 102, since the outgoing gas is higher than the return gas, the first pressure sensor 164 and the second pressure sensor 166 will be referred to as a low pressure sensor and a high pressure sensor, respectively. There is also.

The first pressure sensor 164 measures the pressure of the low pressure pipe 142, and the second pressure sensor 166 is provided to measure the pressure of the high pressure pipe 144. The first pressure sensor 164 is installed in the storage tank 150, for example, and measures the pressure of the return gas from which pulsation is removed in the storage tank 150. The first pressure sensor 164 may be provided at any position of the low pressure pipe 142. The second pressure sensor 166 is provided between the oil separator 154 and the adsorber 156. The second pressure sensor 166 may be provided at any position of the high pressure pipe 144.

However, the first pressure sensor 164 and the second pressure sensor 166 may be provided outside the first compressor unit 102, for example, the first suction pipe 132 and the first discharge pipe 128. ) May be provided. In addition, the bypass mechanism 152 may also be provided outside the first compressor unit 102. For example, the bypass pipe 158 connects the first suction pipe 132 and the first discharge pipe 128 to each other. You may do it.

The compressor structure 136 shown in FIG. 3 includes a compressor body 140, a low pressure pipe 142, a high pressure pipe 144, a suction port 146, a discharge port 148, a storage tank 150, and a bypass mechanism. 152, the oil separator 154, the adsorber 156, the bypass pipe 158, the equalizing valve 160, the relief valve 162, the first pressure sensor 164, the second pressure sensor 166, Compressor motor 172 is included. These components are included in the compressor case body 138.

4 is a control block diagram of the cryopump system 1000 according to the present embodiment. 4 shows a main part of a cryopump system 1000 according to an embodiment of the present invention. Since details of one of the cryopumps 10 are shown inside, and the other cryopumps 10 are the same, the illustration is omitted. Similarly, the first compressor unit 102 is shown in detail, and since the second compressor unit 104 is the same, the illustration of the interior is omitted.

As described above, the CP controller 100 is communicatively connected to the IO modules 50 of the cryopumps 10. The IO module 50 includes a refrigerator inverter 52 and a signal processor 54. The refrigerator inverter 52 adjusts the power of a prescribed voltage and frequency supplied from an external power source, for example, a commercial power source, and supplies the refrigerator motor 26 to the refrigerator motor 26. The voltage and frequency to be supplied to the refrigerator motor 26 are controlled by the CP controller 100.

The CP controller 100 determines the command control amount based on the sensor output signal. The signal processing unit 54 relays the command control amount transmitted from the CP controller 100 to the refrigerator inverter 52. For example, the signal processor 54 converts the command signal from the CP controller 100 into a signal that can be processed by the refrigerator inverter 52 and transmits the signal to the refrigerator inverter 52. The command signal includes a signal indicating an operating frequency of the refrigerator motor 26. In addition, the signal processing unit 54 relays the outputs of various sensors of the cryopump 10 to the CP controller 100. For example, the signal processor 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 first temperature sensor 23 and the second temperature sensor 25 are connected to the signal processing unit 54 of the IO module 50. As described above, the first temperature sensor 23 measures the temperature of the first cooling stage 22 of the refrigerator 12, and the second temperature sensor 25 measures the temperature of the second cooling stage 24 of the refrigerator 12. Measure the temperature. The first temperature sensor 23 and the second temperature sensor 25 periodically measure the temperatures of the first cooling stage 22 and the second cooling stage 24, respectively, and output a signal indicating the measured temperature. The measured values of the first temperature sensor 23 and the second temperature sensor 25 are input to the CP controller 100 at predetermined time intervals and stored in a predetermined storage area of the CP controller 100.

The CP controller 100 controls the refrigerator 12 based on the temperature of the cryopanel. The CP controller 100 gives a command signal to the refrigerator 12 so that the room temperature of the cryopanel follows the target temperature. For example, the CP controller 100 generates a freezer inverter command signal by feedback control so as to minimize the deviation between the target temperature of the first stage cryopanel and the measured temperature of the first temperature sensor 23. The refrigerator inverter command signal is provided to the refrigerator inverter 52 from the CP controller 100 via the IO module 50. The refrigerator inverter 52 controls the operation frequency of the refrigerator motor 26 in accordance with the refrigerator inverter command signal. According to the operating frequency of the refrigerator motor 26, the rotation speed of the refrigerator motor 26, that is, the frequency of the heat cycle of the refrigerator 12 is determined. The target temperature of the first stage cryopanel is determined as a specification according to, for example, a process performed in the vacuum chamber 80. In this case, the second cooling stage 24 and the panel structure 14 of the refrigerator 12 are cooled to a temperature determined by the specifications of the refrigerator 12 and the heat load from the outside.

When the measured temperature of the first temperature sensor 23 is higher than the target temperature, the CP controller 100 outputs a refrigerator inverter command signal to the IO module 50 so that the operating frequency of the refrigerator motor 26 increases. . In association with the increase in the motor operating frequency, the frequency of the heat cycle in the refrigerator 12 is also increased, and the first cooling stage 22 of the refrigerator 12 is cooled toward the target temperature. On the contrary, when the measured temperature of the first temperature sensor 23 is lower than the target temperature, the operating frequency of the refrigerator motor 26 is decreased and the first cooling stage 22 of the refrigerator 12 is heated up toward the target temperature. .

Usually, the target temperature of the 1st cooling stage 22 is set to a fixed value. Accordingly, the CP controller 100 outputs a freezer inverter command signal so that the operating frequency of the refrigerator motor 26 increases when the heat load on the cryopump 10 increases, and heat load on the cryopump 10. When is reduced, the refrigerator inverter command signal is output so that the operating frequency of the refrigerator motor 26 is decreased. However, the target temperature may be appropriately varied, for example, the target temperature of the cryopanel may be set in order so as to realize the target atmospheric pressure in the exhaust target volume. In addition, the CP controller 100 may control the operating frequency of the refrigerator motor 26 to match the room temperature degree of the second stage cryopanel to the target temperature.

In a typical cryopump, the frequency of the heat cycle is always constant. It is set to operate at a relatively large frequency to enable rapid cooling from the normal temperature to the pump operating temperature, and when the heat load from the outside is small, the temperature of the cryopanel is adjusted by heating by a heater. Therefore, power consumption increases. On the other hand, in this embodiment, since the heat cycle frequency is controlled according to the heat load on the cryopump 10, the cryopump excellent in energy saving can be realized. In addition, the necessity of providing a heater necessarily contributes to the reduction of power consumption.

The CP controller 100 is connected to the compressor controller 168 so that communication is possible. The control unit of the cryopump system 1000 according to the embodiment of the present invention is composed of a plurality of controllers including a CP controller 100 and a compressor controller 168. In another embodiment, the control unit of the cryopump system 1000 may be constituted by a single CP controller 100, and the compressor units 102 and 104 may be provided with an IO module instead of the compressor controller 168. You may also In this case, the IO module relays a control signal between the CP controller 100 and each component of the compressor units 102 and 104. In addition, the compressor controller 168 may constitute a part of the CP controller 100.

The compressor controller 168 controls the first compressor unit 102 based on the control signal from the CP controller 100 or independent of the CP controller 100. In one embodiment, the compressor controller 168 receives signals indicating various set values from the CP controller 100 and controls the first compressor unit 102 using the set values. The compressor controller 168 determines the command control amount based on the sensor output signal. The compressor controller 168, like the CP controller 100, includes a CPU that executes various calculation processes, a ROM that stores various control programs, a RAM used as a work area for data storage and program execution, an input / output interface, and a memory. And the like.

In addition, the compressor controller 168 transmits a signal indicating the operation state of the first compressor unit 102 to the CP controller 100. The signal indicating the operation state may be, for example, a measured pressure of the first pressure sensor 164 and the second pressure sensor 166, an opening degree or control current of the relief valve 162, an operating frequency of the compressor motor 172, or the like. It includes.

The first compressor unit 102 includes a compressor inverter 170 and a compressor motor 172. The compressor motor 172 is a motor whose operating frequency is variable by operating the compressor main body 140, and is provided in the compressor main body 140. Similarly to the refrigerator motor 26, various motors can be employed as the compressor motor 172. The compressor controller 168 generates a compressor inverter command signal and outputs it to the compressor inverter 170. The compressor inverter 170 controls the operation frequency of the compressor motor 172 in accordance with 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 the power of a prescribed voltage and frequency supplied from an external power source, for example, a commercial power source, and supplies it to the compressor motor 172 according to the compressor inverter command signal. The voltage and frequency to be supplied to the compressor motor 172 are determined by the compressor inverter command signal.

The compressor controller 168 is connected with various sensors including a first pressure sensor 164 and a second pressure sensor 166. As described above, the first pressure sensor 164 periodically measures the pressure at the suction side of the compressor main body 140, and the second pressure sensor 166 periodically measures the pressure at the discharge side of the compressor main body 140. The measured values of the first pressure sensor 164 and the second pressure sensor 166 are input to the compressor controller 168 at predetermined time intervals, and are stored and stored in a predetermined storage area of the compressor controller 168.

The relief valve 162 mentioned above is connected to the compressor controller 168. A relief valve driver 174 for driving the relief valve 162 is provided along with the relief valve 162, and a relief valve driver 174 is connected to the compressor controller 168. The compressor controller 168 generates a relief valve command signal and outputs it 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 its opening degree. Thus, the relief valve 162 is provided in the bypass piping 158 so as to control the flow volume of the bypass piping 158 according to the relief valve command signal. The relief valve driver 174 may be included in the compressor controller 168.

The compressor controller 168 controls the compressor main body 140 to maintain the differential pressure (hereinafter sometimes referred to as compressor differential pressure) between the entrances and exits of the compressor unit 102 at the target differential pressure. For example, the compressor controller 168 executes feedback control so that the differential pressure between the entrances and exits of the compressor unit 102 is a constant value. In one embodiment, the compressor controller 168 obtains the compressor differential pressure from the measured values of the first pressure sensor 164 and the second pressure sensor 166. The compressor controller 168 determines the operating frequency of the compressor motor 172 to match the compressor differential pressure with the target value. The compressor controller 168 controls the compressor inverter 170 to realize the operation frequency. However, the target value of the differential pressure may be changed during the execution of the differential pressure constant control.

By such a differential pressure constant control, further reduction in power consumption is realized. 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 cryopanel temperature regulation control described above. Then, the amount of working gas required by the refrigerator 12 becomes small. At that time, the amount of gas exceeding the required amount can be sent from the compressor unit 102. Therefore, the differential pressure between the entrances and exits of the compressor unit 102 tries to expand. However, in this embodiment, the operating frequency of the compressor motor 172 is controlled to make the compressor differential pressure constant. In this case, if the differential pressure is reduced to the target value, the operating frequency of the compressor motor 172 is reduced. Therefore, the power consumption can be reduced as compared with the case where the compressor is always operated at a constant operating frequency as in a typical cryopump.

On the other hand, when the heat load on the cryopump 10 increases, the operating frequency of the compressor motor 172 is increased so as to keep the compressor differential pressure constant. For this reason, since the quantity of gas supplied to the refrigerator 12 can be ensured enough, the deviation from the target temperature of the cryopanel temperature resulting from the increase of heat load can be suppressed to the minimum.

In particular, when the timing of opening the valve to the high pressure side for working gas intake overlaps or approaches very closely in the plurality of refrigerators 12, the total amount of the required gas is increased. For example, when the compressor is simply operated at a constant discharge flow rate or when the discharge pressure of the compressor is insufficient, the amount of gas supplied to the refrigerator to open the valve afterwards is smaller than the refrigerator to open and intake the valve first. The difference in the amount of supply gas between the plurality of refrigerators 12 causes variation in the freezing capacity between the refrigerators 12. In comparison with such a case, by performing the differential pressure control, it is possible to sufficiently secure the operating gas flow rate to the refrigerator 12. The differential pressure control not only contributes to energy saving, but can also suppress variations in the freezing capacity between the plurality of refrigerators 12.

5 is a diagram for explaining the control flow of the compressor unit operation control 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 intervals during the operation of the cryopump 10. This processing is executed independently of the other compressor units 102 and 104 in the compressor controller 168 of each compressor unit 102 and 104. In FIG. 5, the part which shows arithmetic processing in the compressor controller 168 is divided by the broken line, and the part which shows the operation | movement of the hardware of the compressor units 102 and 104 is divided by the dashed-dotted line.

The compressor controller 168 includes a control amount computing unit 176. The control amount calculation unit 176 is configured to calculate, for example, the command control amount for at least the differential pressure constant control. In this embodiment, the calculated command control amount is allocated to the operating frequency of the compressor motor 172 and the opening degree of the relief valve 162, and the differential pressure constant control is executed. In another embodiment, the differential pressure constant control may be executed as the command control amount only one of the operating frequency of the compressor motor 172 and the opening degree of the relief valve 162. 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 described later.

As shown in FIG. 5, the target differential pressure ΔP ₀ is preset and input to the compressor controller 168. The target differential pressure is set in the CP controller 100 and applied to the compressor controller 168, for example. The measured pressure PL on the suction side is measured by the first pressure sensor 164, and the measured pressure PH on the discharge side is measured by the second pressure sensor 166, and the pressure is measured from the respective sensors to the compressor controller 168. Is given. The measurement pressure PL of the first pressure sensor 164 is usually lower than the measurement pressure PH of the second pressure sensor 166.

The compressor controller 168 obtains the measured differential pressure ΔP by subtracting the suction side measured pressure PL from the discharge side measured pressure PH, and subtracts the measured differential pressure ΔP from the set differential pressure ΔP ₀ to obtain the differential pressure deviation e. It further includes a deviation calculation unit 178 to obtain the. The control amount calculation unit 176 of the compressor controller 168 calculates the command control amount D from the differential pressure deviation e by a predetermined control amount calculation process including, for example, PD operation or PID operation.

However, as shown in the figure, the compressor controller 168 may be provided with the deviation calculation part 178 separately from the control amount calculation part 176, and the control amount calculation part 176 may be provided with the deviation calculation part 178. As shown in FIG. Further, an integral calculation unit may be provided at the rear end of the control amount calculation unit 176 to integrate the command control amount D for a predetermined time and give the output distribution processing unit 180.

The compressor controller 168 includes an output distribution processor 180 that distributes the command control amount D to the first command output value D1 and the second command output value D2. The output distribution processing unit 180 determines the first command output value D1 and the second command output value D2 according to the magnitude of the value of the command control amount D. FIG. The output distribution processing unit 180 refers to the output distribution table 181, and thereby determines the first command output value D1 and the second command output value D2 from the command control amount D. The output distribution table 181 is prepared in advance and stored in the output distribution processing unit 180 or the compressor controller 168.

The command control amount D is a parameter corresponding to the target flow rate of the compressor unit. The command control amount D indicates the operating gas flow rate that the compressor unit should send out in order to realize a target pressure such as the target differential pressure ΔP ₀ . However, 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 associated with a target flow rate of the compressor unit by a function or a table, or any parameter correlated with the target flow rate of the compressor unit.

The first command output value D1 is a parameter corresponding to the operation frequency command value of the compressor motor 172. The first command output value D1 may be a parameter associated with the operation frequency command value by a function or a table, or any parameter that correlates with the operation frequency command value. The second command output value D2 is a parameter corresponding to the opening degree command value of the relief valve 162. The second command output value D2 may be a parameter associated with the openness command value by a function or a table, or any parameter correlated with the openness command value.

The compressor controller 168 includes an inverter command unit 182 for generating the compressor inverter command signal E from the first output command value D1, and a relief valve command signal R for the second output command value D2. The relief valve command part 184 produced | generated from this is provided. The compressor inverter command signal E is provided to the compressor inverter 170, and the operation frequency of the compressor main body 140, that is, the compressor motor 172, is controlled in accordance with the command. The compressor inverter command signal E is, for example, a voltage signal indicating an operating frequency command value or other electric signal. Moreover, the relief valve command signal R is provided to the relief valve driver 174, and the opening degree of the relief valve 162 is controlled by the command. The relief valve command signal R is an electric signal indicating the opening degree command value of the relief valve 162, for example, a pulse output signal for driving the solenoid coil.

In this way, the compressor controller 168 receives the relief valve command signal R and the compressor so that the working gas is supplied from the compressor units 102 and 104 to the cryopump 10 (that is, the refrigerator 12) at a target flow rate. Determine the inverter command signal (E). The compressor controller 168 controls the opening degree of the relief valve 162 based on the determined relief valve command signal R. FIG. The compressor controller 168 outputs the relief valve command signal R to the relief valve driver 174, whereby the relief valve 162 is opened in accordance with the relief valve command signal R. FIG. In addition, the compressor controller 168 controls the operating frequency of the compressor main body 140 based on 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 in accordance with the compressor inverter command signal E.

The pressure of helium, which is the working gas, is determined by the operating states of the compressor main body 140 and the relief valve 162 and the characteristics of the pipes and tanks. The helium pressure determined in this way is measured by the first pressure sensor 164 and the second pressure sensor 166.

As described above, in each of the compressor units 102 and 104, the differential pressure schedule control is independently performed by the respective compressor controllers 168. The compressor controller 168 performs feedback control so as to minimize the differential pressure difference e (preferably to zero).

However, the deviation e shown in FIG. 5 is not limited to the deviation of a differential pressure. In one embodiment, the compressor controller 168 may perform discharge pressure control for calculating the command control amount from the deviation between the discharge side measured pressure PH and the set pressure. In this case, the set pressure may be the upper limit of the discharge side pressure of the compressor. The compressor controller 168 may calculate the command control amount from the deviation from the discharge side measurement pressure PH when the discharge side measurement pressure PH exceeds this upper limit. The upper limit value may be appropriately empirically or experimentally set based on, for example, the maximum discharge pressure of the compressor that guarantees the exhaust capacity of the cryopump 10.

In this way, excessive rise of discharge pressure can be suppressed and safety can be raised more. Therefore, the discharge pressure control is an example of protection control for the compressor unit.

In addition, in one embodiment, the compressor controller 168 may perform suction pressure control for calculating the command control amount from the deviation between the suction side measured pressure PL and the set pressure. In this case, the set pressure may be a lower limit of the suction side pressure of the compressor. The compressor controller 168 may calculate the command control amount from the deviation from the suction side measurement pressure PL when the suction side measurement pressure PL is less than this lower limit. The lower limit value may be appropriately empirically or experimentally set based on, for example, the lowest suction pressure of the compressor that guarantees the exhaust capacity of the cryopump 10.

By doing in this way, it becomes possible to suppress the excessive temperature rise of the compressor main body resulting from the fall of the operating gas flow volume accompanying the fall of suction pressure. In addition, it may be possible to continue the operation for some period of time without stopping the operation immediately when gas leakage occurs from the piping of the working gas and preventing excessive dropping. Therefore, suction pressure control is an example of protection control for a compressor unit.

6 is a diagram schematically illustrating an output distribution table 181 according to one embodiment of the present invention. The vertical axis represents the first output command value D1 (solid line) and the second output command value D2 (dashed line), and the horizontal axis represents the command control amount D. The first output command value D1 is indicated by a solid line, and the second output command value D2 is indicated by a broken line. As described above, the first output command value D1 and the second output command value D2 correspond to or correlate with the operation frequency command value and the opening degree command value, respectively, and the command control amount D is the target flow rate of the compressor unit. Corresponds to or correlates to. Therefore, the output distribution table 181 has a relationship between the operation 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. Indicates.

The range of the value which the 1st output command value D1 can take is previously limited to the 1st section and the 2nd section. The first section is a range from the lower limit value D1L to the first value D11, and the second section is a range from the second value D12 to the upper limit value D1U. Since the first output command value D1 correlates with the operation frequency command value, the lower limit value D1L, the first value D11, the second value D12, and the upper limit value D1U shown are respectively the lower limit values of the operation frequency. , The first value, the second value, and the upper limit value.

Therefore, by the output distribution table 181, the range of values that the driving frequency can take is previously determined by the first driving frequency section from the lower limit value to the first value and the second driving frequency section from the second value to the upper limit value. It is limited. The lower limit of the operating frequency is larger than zero, for example, between 20 Hz and 40 Hz, or between 25 Hz and 35 Hz, for example, may be 30 Hz. The upper limit of the operating frequency is, for example, between 70 Hz and 90 Hz, or between 75 Hz and 85 Hz, and may be, for example, 78 Hz. The upper limit value and the lower limit value of the operating frequency are predetermined as, for example, the specifications of the compressor.

The section from the first value D11 to the second value D12 is not used. The unused frequency section from the first value to the second value of the operating frequency corresponding to this section is at least a part of the compressor structure 136 (for example, the low pressure pipe 142, the high pressure pipe 144, the bypass pipe ( And at least one natural frequency ω 0 for the pipe (such as 158). The first value and the second value of the operating frequency are between the lower limit value and the upper limit value, and the second value is larger than the first value. The natural frequency (ω 0) is already known by the designer's empirical findings, experiments or simulations. The first value is set to a value smaller than the natural frequency ω 0 and the second value is set to a value larger than the natural frequency ω 0.

The output distribution table 181 stores the first value d1, the second value d2, the third value d3, and the fourth value d4 of the command control amount D, and the first output command value D1. ), The lower limit value D1L, the first value D11, the second value D12, and the upper limit value D1U. The command control amount D and the set of the first output command value D1 (that is, (d1, D1L), (d2, D11), (d3, D12), and (d4, D1U)) specified in this way are The relationship between the command control amount D and the first output command value D1 is determined by linear interpolation.

As shown in Fig. 6, when the command control amount D is between the minimum value d0 and the first value d1, the first output command value D1 takes the lower limit value D1L. When the command control amount D is between the first value d1 and the second value d2, the first output command value D1 is between the lower limit value D1L and the first value D11, The first output command value D1 is in a linear or proportional relationship with the command control amount D. FIG. When the command control amount D is between the second value d2 and the third value d3, the first output command value D1 takes the second value D12. When the command control amount D is between the third value d3 and the fourth value d4, the first output command value D1 is between the second value D12 and the upper limit value D1U. The first output command value D1 is in a linear or proportional relationship with the command control amount D. FIG.

In accordance with the relationship between the command control amount D and the first output command value D1, the output distribution table 181 provides the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the like of the compressor main body 140. And the upper limit discharge flow rate correspond to the lower limit value, the first value, the second 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 first discharge flow rate, the operating frequency linearly increases from the lower limit value to the first value. When the target flow rate reaches the first discharge flow rate, the operating frequency is switched from the first value to the second value and discontinuously increases. When the target flow rate increases from the first discharge flow rate to the second discharge flow rate, the operating frequency is fixed to the second value. When the target flow rate increases from the second discharge flow rate to the upper limit value, the operating frequency linearly increases from the second value to the upper limit value. When the target flow rate decreases, the operating frequency changes in the opposite direction.

In addition, the output distribution table 181 stores the minimum value d0, the first value d1, the second value d2, the third value d3, and the fourth value d4 of the command control amount D, The maximum value D22, the minimum value D20, the intermediate value D21, the minimum value D20, and the minimum value D20 of the second output command value D2 are corresponded. The maximum value D22 of the second output command value D2 may correspond to the maximum opening degree of the relief valve 162. The minimum value D20 of the second output command value D2 may correspond to the closing of the relief valve 162. The intermediate value D21 of the second output command value D2 may correspond to any intermediate opening degree of the relief valve 162. The relationship between the command control amount D and the second output command value D2 is determined by linear interpolation between the command control amount D and the sets of the second output command value D2.

As shown in FIG. 6, when the command control amount D is between the minimum value d0 and the first value d1, the second output command value D2 is between the maximum value D22 and the minimum value D20. The second output command value (D2) is in a linear or proportional relationship with the command control amount (D). When the command control amount D is between the first value d1 and the second value d2, the second output command value D2 takes the minimum value D20. When the command control amount D is between the second value d2 and the third value d3, the second output command value D2 is between the intermediate value D21 and the minimum value D20. 2 The output command value D2 has a linear or proportional relationship with the command control amount D. When the command control amount D is between the third value d3 and the fourth value d4, the second output command value D2 takes the minimum value D20.

Due to the relationship between the command control amount D and the second output command value D2, the output distribution table 181 sets the discharge flow rate of the compressor main body 140 to the opening degree of the relief valve 162. Flow rate of the pass pipe 158). When the target flow rate of the compressor unit is zero, the relief valve 162 becomes the maximum opening degree, and when the target flow rate increases to the lower limit discharge flow rate, the opening degree of the relief valve 162 decreases gradually. When the target flow rate increases from the lower limit discharge flow rate to the first discharge flow rate, the relief valve 162 is closed. When the target flow rate reaches the first discharge flow rate, the relief valve 162 is opened to an intermediate opening degree. When the target flow rate increases from the first discharge flow rate to the second discharge flow rate, the opening degree of the relief valve 162 decreases gradually. When the target flow rate increases from the second discharge flow rate to the upper limit value, the relief valve 162 is closed. When the target flow decreases, the opposite is the opening.

By referring to such an output distribution table 181, the compressor controller 168, when the target flow rate is between the first discharge flow rate and the second discharge flow rate, the inverter command signal ( Determine E). In addition, the compressor controller 168 receives the relief valve command signal 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 according to the inverter command signal. Determine (R).

According to the compressor unit according to the embodiment, since the unused section of the operating frequency is determined to include the natural frequency ω 0 of the compressor structure 136, the resonance of the compressor structure 136 due to the operation of the compressor main body 140 is It is difficult to occur. In addition, since the inverter command signal E is determined so that the operating frequency takes the second value, the working gas is the compressor body 140 at the total flow rate in which the surplus flow rate (corresponding to the difference flow rate above) is added to the target flow rate. Is discharged from the high pressure pipe (144). Since the relief valve command signal R is determined so that the flow rate of the bypass pipe 158 corresponds to the excess flow rate, the working gas is recovered from the high pressure pipe 144 to the low pressure pipe 142. In this way, the compressor units 102 and 104 can supply the working gas to the refrigerator 12 at a target flow rate. Without the need for structural design changes, it is possible to prevent or mitigate the resonance that may occur in the compressor unit of the inverter drive for the cryogenic refrigerator, and to secure the required discharge flow rate.

However, when the target flow rate is between the first discharge flow rate and the second discharge flow rate, instead of fixing the operation frequency to the second value, the inverter command signal E so that the operation frequency is set to the second operation frequency section. May be determined. In this case, since the operation frequency takes a value larger than the second value, the discharge flow rate of the compressor main body 140 increases. By increasing the opening degree of the relief valve 162 and increasing the flow rate of the bypass pipe 158, it is possible to cancel the surplus flow rate. However, since the smaller the operating frequency can reduce the power consumption, it is preferable to set the operating frequency to the second value as described above.

In addition, by referring to the output distribution table 181, the compressor controller 168 outputs the inverter command signal so that when the target flow rate is between the lower limit discharge flow rate and the first discharge flow rate, the operation frequency is set to the first operation frequency section. Determine (E). At the same time, the compressor controller 168 determines the relief valve command signal R such that the relief valve 162 is closed. In this case, the discharge flow rate of the compressor unit is controlled only by the compressor inverter 170. The relief valve 162 is not used for discharge flow rate control.

The compressor controller 168 determines the inverter command signal E so that when the target flow rate is between the second discharge flow rate and the upper limit discharge flow rate, the operation frequency is set to the second operation frequency section. At the same time, the compressor controller 168 determines the relief valve command signal R such that the relief valve 162 is closed. In this case, the discharge flow rate of the compressor unit is controlled only by the compressor inverter 170. The relief valve 162 is not used for discharge flow rate control.

The compressor controller 168 determines the inverter command signal E so that the operation frequency takes a lower limit when the target flow rate is between zero and the lower limit discharge flow rate. At the same time, the compressor controller 168 determines the relief valve command signal R such that the flow rate of the bypass pipe 158 matches the difference flow rate described above. In this case, the discharge flow rate of the compressor unit is controlled only by the relief valve 162.

The compressor controller may smooth the relief valve command signal R and / or the inverter command signal E when the operation frequency is switched from the first value to the second value. As the smoothing process, temporal smoothing such as a low pass filter or a moving average, and any other known smoothing process can be adopted. In this way, it is possible to prevent or alleviate the adverse effect on the helium gas flow rate due to the discontinuous change of the relief valve command signal R and / or the inverter command signal E.

In the above, this invention was demonstrated based on the Example. The present invention is not limited to the above embodiments, various design changes are possible, various modifications are possible, and such modifications are within the scope of the present invention.

In one embodiment, the CP controller 100 may control the compressor units 102 and 104. The CP controller 100 may include the compressor controller 168. The CP controller 100 may be provided with the compressor inverter 170. The CP controller 100 includes a relief 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 relief valve. At least one of the command part 184 may be provided.

12 freezer
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
Industry Availability
INDUSTRIAL APPLICABILITY The present invention can be used in the field of a compressor unit for a cryogenic refrigerator and a cryopump system.

Claims (6)

As a compressor unit for cryogenic refrigerator,
A compressor main body for compressing and discharging a working gas of a cryogenic refrigerator, a compressor motor for operating the compressor main body with a variable operating frequency, a high pressure pipe connected to the compressor main body to discharge working gas from the compressor main body, and the compressor A low pressure pipe connected to the compressor main body so that the working gas is sucked into the main body, a bypass pipe connecting the high pressure pipe to the low pressure pipe bypassing the compressor main body, and a flow rate of the bypass pipe according to a valve command signal. Compressor structure including a flow control valve provided in the bypass pipe to control;
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 such that a working gas is supplied from the compressor unit to the cryogenic freezer at a target flow rate.
The range of values that the driving frequency can take is limited in advance to a first driving frequency section from a lower limit value greater than zero to a first value, and a second driving frequency section from a second value to an upper limit value, and the second value. Is greater than the first value and the first value and the second value are such that the unused frequency interval from the first value to the second value comprises at least one natural frequency for at least a portion of the compressor structure. The lower limit value, the first value, the second value, and the upper limit value of the operating frequency correspond to the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge flow rate of the compressor main body, respectively. and,
The compressor controller, when the target flow rate is between the first discharge flow rate and the second discharge flow rate, determines the inverter command signal so that the operation frequency is set to the second operation frequency section. And the valve command signal is determined such that the flow rate of the bypass pipe coincides with the difference flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body obtained according to the inverter command signal. The method of claim 1,
And the compressor controller determines the inverter command signal so that the operating frequency takes the second value when the target flow rate is between the first discharge flow rate and the second discharge flow rate. . The method according to claim 1 or 2,
The compressor controller,
When the target flow rate is between the lower limit discharge flow rate and the first discharge flow rate, the inverter command signal is determined so that the operation frequency is set to the first operation frequency section, and the flow control valve is closed. Determine the valve command signal,
When the target flow rate is between the second discharge flow rate and the upper limit discharge flow rate, the inverter command signal is determined such that the operation frequency is set to the second operation frequency section, and the flow control valve is closed. And the valve command signal is determined. The method according to any one of claims 1 to 3,
The compressor controller determines the inverter command signal so that the operation frequency takes the lower limit when the target flow rate is between zero and the lower limit discharge flow rate, and the flow rate of the bypass pipe flows to the differential flow rate. And the valve command signal is determined to coincide with the compressor. The method according to any one of claims 1 to 4,
And the compressor controller performs a smoothing process on the valve command signal and / or the inverter command signal when the operation frequency is changed from the first value to the second value. As a cryopump system,
A cryopump having a cryopanel, a cryogenic chiller for cooling the cryopanel,
A compressor main body for compressing and discharging the working gas of the cryogenic refrigerator, a compressor motor for operating the compressor main body having a variable operating frequency, a high pressure pipe connected to the compressor main body to discharge working gas from the compressor main body, and A low pressure pipe connected to the compressor main body so that the working gas is sucked into the compressor main body, a bypass pipe connecting the high pressure pipe to the low pressure pipe bypassing the compressor main body, and a flow rate of the bypass pipe according to a valve command signal. Compressor unit having a compressor structure including a flow control valve provided in the bypass pipe to control the;
A compressor inverter for controlling the operation frequency of the compressor motor according to the inverter command signal;
And a controller configured to determine the valve command signal and the inverter command signal such that a working gas is supplied from the compressor unit to the cryogenic freezer at a target flow rate.
The range of values that the driving frequency can take is limited in advance to a first driving frequency section from a lower limit value greater than zero to a first value, and a second driving frequency section from a second value to an upper limit value, and the second value. Is greater than the first value and the first value and the second value are such that the unused frequency interval from the first value to the second value comprises at least one natural frequency for at least a portion of the compressor structure. The lower limit value, the first value, the second value, and the upper limit value of the operating frequency correspond to the lower limit discharge flow rate, the first discharge flow rate, the second discharge flow rate, and the upper limit discharge flow rate of the compressor main body, respectively. and,
When the target flow rate is between the first discharge flow rate and the second discharge flow rate, the controller determines the inverter command signal so that the operation frequency is set to the second operation frequency section, and the inverter The cryopump system, characterized in that the valve command signal is determined such that the flow rate of the bypass pipe coincides with the differential flow rate obtained by subtracting the target flow rate from the discharge flow rate of the compressor main body obtained according to the command signal.