KR20220164842A - Cryopump system and meothod of controlling the cryopump system - Google Patents

Abstract

The present invention relates to a cryogenic pump system capable of minimizing power consumption and increasing durability and operational efficiency of the cryogenic pump system and a method for controlling the cryogenic pump system. According to the present invention, the cryogenic pump system comprises: a plurality of cryogenic pumps; a compressor for compressing working gas for operating a cryogenic freezer of the plurality of cryogenic pumps; a sensor unit for measuring the operation load of the cryogenic pump; and a control unit variably controlling the operating frequency of the cryogenic freezer or the compressor by receiving the measurement value of the sensor unit.

Description

Cryogenic pump system and cryogenic pump system control method {CRYOPUMP SYSTEM AND MEOTHOD OF CONTROLLING THE CRYOPUMP SYSTEM}

The present invention relates to a cryogenic pump system and a method for controlling a cryogenic pump system, and more particularly, to a cryogenic pump system and method for controlling a cryogenic pump system in which a high vacuum is formed in a vacuum chamber by driving a plurality of cryogenic pumps with a compressor.

A cryogenic pump system including a cryogenic pump including a cryogenic freezer and a compressor for compressing a working gas of the cryogenic freezer is known. The cryogenic pump system supplies high-pressure working gas (eg, helium) compressed by a compressor to the cryogenic freezer of the cryogenic pump, and sends the low-pressure working gas, which is expanded and reduced in pressure in the cryogenic freezer, back to the compressor to circulate In the process, it is a system that condenses or adsorbs gas using cold heat to form a high vacuum.

For example, the cryogenic pump system is used to form a high vacuum in a vacuum chamber during a semiconductor/display process, and is generally used as a system in which a plurality of cryogenic pumps are connected in parallel to a compressor.

The compressor and the cryogenic freezer operate at a predetermined operating frequency, respectively. Conventionally, the compressor and the cryogenic freezer are independently operated. In particular, regardless of the operating conditions of the cryogenic pump, the compressor was operated at the rated level, but since the compressor consumes a lot of power, there is a problem in that the efficiency of electricity use is lowered by the compressor operated at the rated level.

Cryogenic freezers are largely divided into regenerative and recuperative types according to the cooling method. Among them, the regenerative cryogenic chiller is suitable for relatively small cryogenic chillers (based on low-temperature part temperature of 77K, refrigerating capacity mW-kW), and is characterized in that the working gas does not flow in one direction but reciprocates in both directions.

The GM cryogenic freezer used in the cryogenic pump is also a type of regenerative cryogenic freezer. The piston inside reciprocates to obtain a cooling effect, and pressure perturbation occurs in this process. In order to obtain a cooling effect by the reciprocating motion of the piston existing inside the GM cryogenic freezer, the airtightness between the piston and the cylinder surrounding it must be maintained, which is directly related to the lifespan of the GM cryogenic freezer. The life of the GM cryogenic freezer can be seen as the same as that of the cryogenic pump. Therefore, the longer the lifespan of the cryogenic high vacuum pump, the higher the efficiency of the semiconductor/display process.

Conventionally, a method of increasing the operating frequency of the GM cryogenic freezer was used for rapid cooling during initial cooling after the regeneration of the cryogenic pump was completed, but in general operation, it is operated at a constant frequency regardless of the operating load, reducing the efficiency of the vacuum process and There was also a problem of poor durability of the pump.

Japanese Laid-open Patent No. 2018-127929

Accordingly, an object of the present invention is to solve such conventional problems, and to minimize power consumption by variably controlling the operation of a compressor or a cryogenic freezer according to the operation load of a cryogenic pump, and durability and operation of a cryogenic pump system. An object of the present invention is to provide a cryogenic pump system capable of increasing efficiency and a method for controlling the cryogenic pump system.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The above object, according to the present invention, a plurality of cryogenic pumps; a compressor for compressing working gas for operating the cryogenic freezer of the plurality of cryogenic pumps; a sensor unit measuring an operating load of the cryogenic pump; and a control unit receiving a measurement value of the sensor unit and variably controlling an operating frequency of the cryogenic freezer or the compressor.

Here, the sensor unit may be at least one of a temperature sensor for measuring the temperature of the cryogenic pump and a pressure sensor for measuring the degree of vacuum.

Here, the control unit may vary the operating frequency of the compressor according to the number of cryogenic pumps connected to and operating with the compressor.

Here, the control unit may vary the operating frequency of the compressor according to the operation load of the cryogenic pump measured by the sensor unit.

Here, the control unit may vary the operating frequency of the cryogenic freezer according to the operation load of the cryogenic pump measured by the sensor unit.

Here, the control unit may divide the operation mode of the cryogenic freezer and vary the operating frequency of the cryogenic freezer according to the operation mode.

Here, the control unit may operate the cryogenic freezer by controlling the operating phase differently for each cryogenic pump.

Here, the control unit may sequentially differently control the operating phases of the cryogenic freezers of the plurality of cryogenic pumps so that the sum of the flow rates of the operating gases supplied to the cryogenic freezers has a small variation over time.

In addition, the above object is, according to the present invention, a method for controlling a cryogenic pump system including a plurality of cryogenic pumps and a compressor for compressing working gas for operating a cryogenic freezer of the plurality of cryogenic pumps, wherein the cryogenic pump is operated measuring the load; and variably controlling the operating frequency of the cryogenic freezer or the compressor according to the measured operating load.

According to the cryogenic pump system and the cryogenic pump system control method of the present invention as described above, there is an advantage in that power consumption can be reduced by variably controlling a compressor according to an operating load.

In addition, there is an advantage in that process efficiency and durability of the system can be increased by differently controlling the operating frequency of the compressor or the cryogenic refrigerator according to the operating load.

1 is a diagram showing a cryogenic pump system according to an embodiment of the present invention.
2 is a diagram showing the configuration of a cryogenic pump according to an embodiment of the present invention.
3 is a diagram showing the valve phases of the cryogenic freezer for three different cryogenic pumps.
4 is a diagram showing valve phases of a cryogenic freezer for two different cryogenic pumps according to the present invention.
5 is a diagram showing valve phases of a cryogenic freezer for three different cryogenic pumps according to the present invention.

The specific details of the embodiments are included in the detailed description and drawings.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to completely inform the person who has the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numbers designate like elements throughout the specification.

Hereinafter, the present invention will be described with reference to drawings for explaining a cryogenic pump system and a method for controlling a cryogenic pump system according to embodiments of the present invention.

1 is a view showing a cryogenic pump system according to an embodiment of the present invention, FIG. 2 is a view showing the configuration of a cryogenic pump according to an embodiment of the present invention, and FIG. 3 is a view showing three different cryogenic pumps. 4 is a diagram showing the valve phase of the cryogenic freezer for two different cryogenic pumps according to the present invention, and FIG. It is a diagram showing the valve phase of the cryogenic freezer with respect to the cryogenic pump.

The illustrated cryogenic pump system may be used to form a high vacuum inside the vacuum chamber 100 during semiconductor/display processing.

One or a plurality of cryogenic pumps 200 may be mounted in the vacuum chamber 100. In this embodiment, a plurality of cryogenic pumps 200 are mounted. Although the figure shows that three cryogenic pumps 200 are shown, this is merely illustrative and the number of cryogenic pumps 200 is not limited thereto.

The cryogenic pump 200 includes a cryogenic refrigerator 210 . In the present invention, as an example of the cryogenic freezer 210, the GM cryogenic freezer 210 may be used.

The GM cryogenic freezer 210 is a two-stage cryogenic freezer 210 having a first cooling stage 211 and a second cooling stage 216 . The first cylinder 221 and the second cylinder 226 are connected in series, the first cylinder 221 connects the motor housing 235 and the first cooling stage 211, and the second cylinder 226 The 1st cooling stage 211 and the 2nd cooling stage 216 are connected.

A refrigerator motor (not shown) and a valve (not shown) for controlling an internal flow path (pressure) are formed in the motor housing 235, and the valve is operated by the refrigerator motor. The operation of the valve periodically repeats the expansion of the working gas (eg, helium). The refrigerator motor operates according to a control signal from a control unit.

A high-pressure pipe 401 and a low-pressure pipe 406 are connected to the motor housing 235, and the working gas compressed to a high pressure by the compressor 300 is supplied to the cryogenic freezer 210 through the high-pressure pipe 401 to produce a cryogenic temperature. It is expanded and reduced in the expansion chamber in the refrigerator 210 to cool the first cooling stage 211 and the second cooling stage 216, and the reduced pressure working gas is supplied to the compressor 300 again through the low pressure pipe 406. becomes circulating.

The second cooling stage 216 is cooled to a lower temperature than the first cooling stage 211 . For example, the first cooling stage 211 may be cooled to 80K and the second cooling stage 211 may be cooled to 15K.

A first temperature sensor 241 for measuring the temperature of the first cooling stage 211 is mounted on the first cooling stage 211, and the temperature of the second cooling stage 216 is measured on the second cooling stage 216. A second temperature sensor 246 may be mounted.

A shield 251 and a baffle 256 are connected to the first cooling stage 211 to shield radiant heat transfer, and a cryopanel 260 coated with an adsorbent is attached to the second cooling stage 216 so that nitrogen, nitrogen, Gases such as oxygen, hydrogen, and helium are condensed to lower the pressure inside the vacuum chamber 100 .

A gate valve 232 that opens and closes a connection with the vacuum chamber 100 is mounted on an upper end of the housing 230 of the cryogenic pump 200 . When the pressure of the vacuum chamber 100 is reduced to high vacuum, the gate valve 232 is opened to communicate the cryogenic pump 200 and the vacuum chamber 100, and regeneration to remove condensed gas from the cryogenic pump 200 During the process or initial cooling of the cryogenic pump 200, the gate valve 232 is closed.

In the present invention, the compressor 300 is a helium compressor, which compresses helium as a working fluid to a high pressure and supplies it to the cryogenic freezer 210 of the cryogenic pump 200 through the high-pressure pipe 401. The working gas expanded and reduced in the cryogenic freezer 210 is introduced into the compressor 300 again through the low pressure pipe 406 and undergoes a circulation process.

In the present invention, a plurality of cryogenic pumps 200 may be operated by being connected to a single compressor 300 . As shown in FIG. 1 , the high-pressure pipe 401 connected to the high-pressure gas outlet of the compressor 300 may be branched and connected to the high-pressure gas inlet of each cryogenic refrigerator 210 . In addition, the low-pressure pipe 406 connected to the low-pressure gas inlet of the compressor 300 may be branched and connected to the low-pressure gas outlet of each cryogenic refrigerator 210 .

The controller 500 controls the operation of the cryogenic pump 200 and the compressor 300 . In the present invention, the control unit 500 may include a CPU for executing various calculation processes, a computer having a memory and an input/output interface for storing data or programs, a DAQ, an MFC controller, an inverter, a wattmeter, and the like. , It may be modularized and configured by combining these functions.

The control unit 500 may include a cryogenic pump control unit for controlling the operation of the cryogenic pump 200 and a compressor control unit for controlling the operation of the compressor 300 . For example, the cryogenic pump control unit may variably change the cooling capacity through phase control of valves and pistons through phase control of the freezer motor of the cryogenic freezer 210 . In addition, the compressor control unit may control the flow rate of the high-pressure working gas discharged from the compressor 300 by controlling the stroke phase of the compressor 300 through the rotation speed control of the compressor motor.

The sensor unit measures the operating load of the cryogenic pump 200 .

The sensor unit may include a sensor that measures the temperature of the cryogenic pump 200 . For example, the cryogenic pump 200 includes the first temperature sensor 241 for measuring the temperature of the first cooling stage 211 and the second temperature sensor 246 for measuring the temperature of the second cooling stage 216. ) to measure the temperature. Alternatively, it may be the pressure sensor 110 that measures the degree of vacuum in the vacuum chamber 100 . The temperature or pressure measured by the sensor unit may be transmitted to the controller 500 .

The control unit 500 receives the measured value of temperature or pressure from the sensor unit, determines the operating load based on the received temperature or pressure measurement value, and variably controls the operating frequency of the cryogenic refrigerator 210 or the compressor 300.

The control unit 500 may variably control the flow rate of the compressor 300 according to the number of connected cryogenic pumps 200 by means of an inverter that controls the frequency of the compressor 300 . Since conventional compressors are generally operated at a rated rate, a constant flow rate is discharged from the compressor 300 regardless of the number of cryogenic pumps 200 connected to the compressor 300 . However, in the present invention, the power consumption of the compressor 300 can be primarily reduced by controlling the flow rate by controlling the frequency of the compressor 300 according to the number of cryogenic pumps 200 connected to the compressor 300. . At this time, the total flow rate of the operating gas supplied from the compressor 300 to each of the cryogenic pumps 200 is measured, and based on this measurement, the output of the inverter is PID controlled to keep the total flow rate discharged from the compressor 300 constant. can

In addition, the control unit 500 variably controls the frequency of the compressor 300 based on the operation load of the cryogenic pump 200 measured by the sensor unit to secondarily reduce the power consumption of the compressor 300. . For example, if the temperatures of the first cooling stage 211 and the second cooling stage 216 measured by the temperature sensors 241 and 246 are higher than the reference value in the operating state, the frequency of the compressor 300 is increased to increase the efficiency of the operating gas. The supply flow rate of the working gas is increased by increasing the supply flow rate, and conversely, when the measured temperatures of the first cooling stage 211 and the second cooling stage 216 maintain the reference value of the operating state or are low, the frequency of the compressor 300 is appropriately lowered. can be adjusted.

In addition, when the load of the cryogenic pump 200 is low by receiving the degree of vacuum in the vacuum chamber 100 measured by the pressure sensor 110 and sufficient vacuum is achieved, the frequency of the compressor 300 is lowered to reduce the consumption of the compressor 300. power can be reduced.

Furthermore, the controller 500 may variably adjust the operating frequency of the cryogenic freezer 210 according to the operating load measured in real time by the sensor unit. When the operating load is small, the operating frequency of the cryogenic freezer 210 may be lowered, and when the operating load is large, the operating frequency of the cryogenic freezer 210 may be increased. That is, the cooling capacity of the cryogenic freezer 210 can be variably adjusted according to the operating load.

Alternatively, the controller 500 may divide the operating mode of the cryogenic pump 200 according to the operating load and variably control the operating frequency of the cryogenic freezer 210 according to the operating mode. For example, when the rated frequency of the cryogenic freezer 210 is 1.2 Hz, when the cryogenic pump 200 needs to be quickly started after initial operation or regeneration, the operating frequency of the cryogenic freezer 210 is increased to 1.5 Hz, and the sensor When the operating load measured from the unit is less than or equal to the reference value, the operating frequency of the cryogenic freezer 210 may be lowered to 1.0 Hz to simultaneously satisfy vacuum efficiency and durability of the cryogenic pump 200 and perform control.

Furthermore, the control unit 500 may differently control the operating phase of the cryogenic refrigerator 210 constituting the cryogenic pump 200 for each cryogenic pump 200 .

By opening and closing the valve located inside the cryogenic temperature, the inside of the cryogenic refrigerator 210 is changed to a high-pressure and low-pressure environment for cooling. In FIGS. 3 to 5, the phase of the valve (motor) is shown. The working gas is not constantly supplied from the compressor 300 to the cryogenic freezer 210, but is supplied while changing the flow rate of the supplied working gas according to the phase of the valve at regular intervals.

At this time, as shown in FIG. 3 , when the phases of the valves (motors) of each cryogenic pump 200 are equally controlled, the maximum flow rate and the minimum flow rate to be supplied from the compressor 300 to the plurality of cryogenic pumps 200 The amplitude between the flow rates becomes large and the operating load of the compressor 300 becomes uneven.

However, as shown in FIG. 5, in the present invention, the phase of the valve (motor) of each cryogenic pump 200 is differently controlled so that the change in flow rate of the working gas discharged from the compressor 300 is small according to time. The load on the compressor 300 can be reduced.

At this time, the cryogenic freezer 210 of each cryogenic pump 200 is operated with respect to the operation cycle of the cryogenic freezer 210 so that the sum of the flow rates of the operating gases supplied to the plurality of cryogenic pumps 200 changes with time to a small extent. It is preferable to operate them sequentially.

5 shows the motor (valve) phase of each cryogenic pump 200 controlled according to the present invention when three cryogenic pumps 200 are connected to the compressor 300, and FIG. The motor (valve) phase of each cryogenic pump 200 controlled according to the present invention when the number of cryogenic pumps 200 are connected is shown. Therefore, the control unit divides the operation of the compressor 300 by changing the phase of the motor (valve) of the cryogenic freezer 210 of each cryogenic pump 200 differently according to the number of cryogenic pumps 200 connected to the compressor 300. can be minimized.

The system control method of a cryogenic pump using the cryogenic pump system according to the present invention described above includes the step of measuring the operation load of the cryogenic pump 200 by the sensor unit, and the control unit 500 using the cryogenic freezer 210 according to the measured operation load. ) or the operation frequency of the compressor 300 may be variably controlled.

At this time, power consumption of the compressor 300 may be primarily reduced by variably controlling the operating frequency of the compressor 300 according to the number of cryogenic pumps 200 connected to and operating with the compressor 300 .

Furthermore, the control unit 500 can variably control the operating frequency of the compressor 300 according to the operating load measured by the sensor unit to secondarily reduce power consumption of the compressor 300 .

In addition, the control unit 500 can improve the vacuum (refrigeration) efficiency and durability of the cryogenic pump 200 by varying the operating frequency of the cryogenic freezer 210 according to the operating load of the cryogenic pump 200 measured by the sensor unit. have.

In addition, the control unit 500 can reduce the load on the compressor 300 by controlling the operation phase of the cryogenic freezer 210 differently for each cryogenic pump 200 .

The scope of the present invention is not limited to the above-described embodiments, but may be implemented in various forms of embodiments within the scope of the appended claims. Anyone with ordinary knowledge in the art to which the invention pertains without departing from the subject matter of the invention claimed in the claims is considered to be within the scope of the claims of the present invention to various extents that can be modified.

100: vacuum chamber
110: pressure sensor
200: cryogenic pump
210: (GM) cryogenic freezer
211: first cooling stage
216: second cooling stage
221: first cylinder
226: second cylinder
230: housing
232: gate valve
235: motor housing
241: first temperature sensor
246: second temperature sensor
251: shield
256 baffle
260: cryopanel
300: compressor
401: high pressure piping
406: low pressure pipe
500: control unit

Claims (9)

a plurality of cryogenic pumps;
a compressor for compressing working gas for operating the cryogenic freezer of the plurality of cryogenic pumps;
a sensor unit measuring an operation load of the cryogenic pump; and
A cryogenic pump system comprising a control unit receiving a measurement value of the sensor unit and variably controlling an operating frequency of the cryogenic freezer or the compressor. According to claim 1,
The cryogenic pump system of claim 1 , wherein the sensor unit is at least one of a temperature sensor for measuring the temperature of the cryogenic pump and a pressure sensor for measuring the degree of vacuum. According to claim 1,
The cryogenic pump system of claim 1 , wherein the control unit varies an operating frequency of the compressor according to the number of the cryogenic pumps connected to the compressor and operating. According to claim 3,
The cryogenic pump system of claim 1 , wherein the control unit varies an operating frequency of the compressor according to the operation load of the cryogenic pump measured by the sensor unit. According to claim 1,
The cryogenic pump system of claim 1 , wherein the control unit varies an operating frequency of the cryogenic freezer according to an operating load of the cryogenic pump measured by the sensor unit. According to claim 5,
The cryogenic pump system of claim 1, wherein the control unit divides the operating modes of the cryogenic freezer and varies the operating frequency of the cryogenic freezer according to the operating modes. According to claim 1,
The cryogenic pump system according to claim 1 , wherein the control unit controls and operates the operation phase of the cryogenic freezer differently for each cryogenic pump. According to claim 7,
wherein the control unit sequentially controls the operation phases of the cryogenic freezers differently so that the sum of the flow rates of the working gases supplied to the cryogenic freezers of the plurality of cryogenic pumps has a small variation over time. A method for controlling a cryogenic pump system comprising a plurality of cryogenic pumps and a compressor for compressing working gas for operating a cryogenic refrigerator of the plurality of cryogenic pumps,
measuring an operation load of the cryogenic pump; and
and variably controlling an operating frequency of the cryogenic refrigerator or an operating frequency of the compressor according to the measured operating load.

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