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CN-117413149-B - Ultralow temperature refrigerator and operation method thereof

CN117413149BCN 117413149 BCN117413149 BCN 117413149BCN-117413149-B

Abstract

The cryogenic refrigerator (10) is provided with an expander (14), a pressure sensor, and a controller (100), wherein the expander (14) is provided with an expander motor (40) provided with a motor rotation shaft (40 a), a displacer (18) which changes the volume of an expansion space of a working gas by linearly reciprocating by the rotation of the motor rotation shaft (40 a), and a rotary valve (42) which controls the intake and exhaust of the working gas with respect to the expansion space by the rotation of the motor rotation shaft (40 a), the pressure sensor measures the pressure of the working gas and outputs a measurement signal indicating the measured pressure, and the controller (100) is configured to receive the measurement signal, detect a characteristic point periodically appearing on the measured pressure during the operation of the cryogenic refrigerator (10), acquire a motor drive waveform indicating the command rotation speed of the motor rotation shaft (40 a) set to be changed during one rotation of the motor rotation shaft (40 a), synchronize the motor drive waveform with the periodically appearing characteristic point, and output the periodically appearing characteristic point.

Inventors

  • MORIE TAKAAKI

Assignees

  • 住友重机械工业株式会社

Dates

Publication Date
20260508
Application Date
20220531
Priority Date
20210610

Claims (12)

  1. 1. An ultralow temperature refrigerator is characterized in that, Comprises an expander, a pressure sensor and a controller, The expander includes an expander motor having a motor rotation shaft, a displacer coupled to the motor rotation shaft so as to reciprocate linearly by rotation of the motor rotation shaft and changing a volume of an expansion space of a working gas by reciprocation, and a rotary valve coupled to the motor rotation shaft so as to rotate by rotation of the motor rotation shaft and controlling intake and exhaust of the working gas with respect to the expansion space, The pressure sensor measures the pressure of the working gas and outputs a measurement signal representing the measured pressure, The controller is configured as follows: the measurement signal is received and the measurement signal is received, Detecting characteristic points periodically appearing on the measured pressure in the operation of the ultra-low temperature refrigerator, A motor drive waveform representing a command rotational speed of the motor rotation shaft set to vary in one rotation of the motor rotation shaft is acquired, The motor driving waveform is output after being synchronized with the periodically occurring feature points.
  2. 2. The cryogenic refrigerator of claim 1, wherein, The controller is configured to select one motor drive waveform from a plurality of motor drive waveforms, and to synchronize the selected motor drive waveform with the periodically occurring feature points and then output the synchronized motor drive waveform, The plurality of motor drive waveforms each represent a command rotational speed of the motor rotation shaft set to be varied in a mutually different manner in one rotation of the motor rotation shaft.
  3. 3. The cryogenic refrigerator of claim 2, wherein, The displacer is configured such that a 1 st angular range in one rotation of the motor rotation shaft passes through a top dead center where the volume of the expansion space is largest, a2 nd angular range in one rotation of the motor rotation shaft subsequent to the 1 st angular range passes through an intermediate point between the top dead center and a bottom dead center where the volume of the expansion space is smallest, The plurality of motor drive waveforms include a1 st motor drive waveform and a 2 nd motor drive waveform, the 1 st motor drive waveform is set such that a command rotational speed of the motor rotation shaft decreases in the 2 nd angle range than in the 1 st angle range, and the 2 nd motor drive waveform is set such that the command rotational speed of the motor rotation shaft increases in the 2 nd angle range than in the 1 st angle range.
  4. 4. The cryogenic refrigerator of claim 3, wherein, The controller is configured to select the 1 st motor driving waveform in an initial cooling from an initial temperature cooling to an ultralow temperature, and to select the 2 nd motor driving waveform in a steady-state operation to maintain the ultralow temperature, which is performed after the initial cooling.
  5. 5. The cryogenic refrigerator of claim 1, wherein, The displacer is configured such that a 1 st angular range in one rotation of the motor rotation shaft passes through a top dead center where the volume of the expansion space is largest, a2 nd angular range in one rotation of the motor rotation shaft subsequent to the 1 st angular range passes through an intermediate point between the top dead center and a bottom dead center where the volume of the expansion space is smallest, The motor drive waveform is set such that the command rotational speed of the motor rotation shaft is reduced in the 2 nd angle range than in the 1 st angle range.
  6. 6. The cryogenic refrigerator according to any one of claims 1 to 5, characterized in that, The controller is configured to acquire and output a motor drive waveform set to a constant commanded rotational speed of the motor rotation shaft when the periodically occurring feature point cannot be detected.
  7. 7. The ultralow temperature refrigerator according to any one of claims 1 to 6, further comprising: compressor and method for manufacturing the same A high-pressure line connecting the compressor and the expander so as to supply a high-pressure working gas from the compressor to the expander, The pressure sensor measures the pressure of the working gas on the high-pressure line.
  8. 8. The cryogenic refrigerator of claim 7, wherein the refrigerator further comprises a heat exchanger, The periodically occurring characteristic point is a characteristic point periodically occurring on the measured pressure of the high-pressure line by sucking working gas into the expansion space through the rotary valve.
  9. 9. The ultralow temperature refrigerator according to any one of claims 1 to 6, further comprising: compressor and method for manufacturing the same A low pressure line connecting the compressor and the expander in such a manner that a low pressure working gas is recovered from the expander to the compressor, The pressure sensor measures the pressure of the working gas on the low pressure line.
  10. 10. The cryogenic refrigerator of claim 9, wherein the refrigerator further comprises a heat exchanger, The periodically occurring characteristic point is a characteristic point which periodically occurs on the measured pressure of the low pressure line by discharging working gas from the expansion space through the rotary valve.
  11. 11. An operation method of an ultralow temperature refrigerator is characterized in that, The cryogenic refrigerator comprises an expander, wherein the expander comprises an expander motor provided with a motor rotation shaft, a displacer connected to the motor rotation shaft in a manner of linear reciprocating movement by the rotation of the motor rotation shaft and changing the volume of an expansion space of working gas by reciprocating movement, and a rotary valve connected to the motor rotation shaft in a manner of rotation by the rotation of the motor rotation shaft and controlling the intake and exhaust of the working gas relative to the expansion space, The method comprises the following steps: Measuring the pressure of the working gas; Detecting characteristic points periodically appearing on the measured pressure in operation of the cryocooler; Acquiring a motor drive waveform representing a command rotational speed of the motor rotational shaft, the command rotational speed of the motor rotational shaft being set to vary in one rotation of the motor rotational shaft, and The motor driving waveform is output after being synchronized with the periodically occurring feature points.
  12. 12. An ultralow temperature refrigerator, comprising: an expander motor provided with a motor rotation shaft; A displacer connected to the motor rotation shaft to reciprocate linearly by the rotation of the motor rotation shaft and changing the volume of an expansion space of the working gas by the reciprocation, wherein a1 st angle range in one rotation of the motor rotation shaft passes through a top dead center where the volume of the expansion space is maximum, a2 nd angle range in one rotation of the motor rotation shaft, which is subsequent to the 1 st angle range, passes through an intermediate point between the top dead center and a bottom dead center where the volume of the expansion space is minimum, and And a controller that causes the expander motor to operate such that the rotational speed of the motor rotation shaft is reduced in the 2 nd angle range compared to the 1 st angle range.

Description

Ultralow temperature refrigerator and operation method thereof Technical Field The invention relates to an ultralow temperature refrigerator and an operation method of the ultralow temperature refrigerator. Background Among the ultra-low temperature refrigerators, for example, a Gifford-McMahon (GM) refrigerator has a displacer reciprocally moved for periodically changing the volume of an expansion space of a working gas. The pressure of the expansion space is appropriately varied in synchronization with the periodic volume variation of the expansion space, so that a refrigeration cycle is constituted in the cryogenic refrigerator. One of typical methods for driving the displacer to reciprocate is a type in which a driving source such as a motor is mechanically coupled to the displacer and the displacer is reciprocated by rotation output from the motor. One revolution of the motor corresponds to one reciprocation of the displacer (i.e., one refrigeration cycle). Technical literature of the prior art Patent literature Patent document 1 Japanese patent laid-open No. 6-101917 Disclosure of Invention Technical problem to be solved by the invention Conventionally, from the viewpoint of improving the cooling capacity of an ultralow temperature refrigerator, it has been attempted to optimally control the displacement speed of a displacer according to the position by changing the rotation speed of a motor that drives the displacer in one rotation. To achieve this, typically, a method may be considered in which the position of the displacer (i.e., the rotational position of the motor) is detected, and the rotational speed of the motor, and thus the moving speed of the displacer, is controlled based on the detected position. However, this method requires an additional position detector to be provided on the motor. Such a position detector is relatively expensive, and may result in an increase in manufacturing cost of the cryocooler. Further, there is a possibility that the motor is increased in size due to the additional installation of the position detector. One of the exemplary objects of an embodiment of the present invention is to enable optimal operation of a cryogenic refrigerator without position detection. Means for solving the technical problems According to one embodiment of the present invention, a cryogenic refrigerator includes an expander including an expander motor including a motor rotation shaft, a displacer coupled to the motor rotation shaft so as to reciprocate linearly by rotation of the motor rotation shaft and changing a volume of an expansion space of a working gas by reciprocation, and a rotary valve coupled to the motor rotation shaft so as to rotate by rotation of the motor rotation shaft and controlling intake and exhaust of the working gas with respect to the expansion space, a pressure sensor for measuring a pressure of the working gas and outputting a measurement signal indicative of the measured pressure, and a controller for receiving the measurement signal, detecting a characteristic point periodically appearing on the measured pressure during operation of the cryogenic refrigerator, acquiring a motor drive waveform indicative of a command rotation speed of the motor rotation shaft set to vary in one rotation of the motor rotation shaft, synchronizing the motor drive waveform with the periodically appearing characteristic point, and outputting the synchronized motor drive waveform. According to one embodiment of the present invention, a method of operating an ultra-low temperature refrigerator is provided. The cryogenic refrigerator is provided with an expander, which is provided with an expander motor having a motor rotation shaft, a displacer connected to the motor rotation shaft so as to reciprocate linearly by the rotation of the motor rotation shaft and changing the volume of an expansion space for the working gas by the reciprocation, and a rotary valve connected to the motor rotation shaft so as to rotate by the rotation of the motor rotation shaft and controlling the intake and exhaust of the working gas to and from the expansion space. The method includes the steps of measuring a pressure of a working gas, detecting a characteristic point periodically appearing on the measured pressure in operation of the cryogenic refrigerator, acquiring a motor drive waveform representing a command rotational speed of a motor rotational shaft set to vary in one rotation of the motor rotational shaft, and outputting the motor drive waveform in synchronization with the periodically appearing characteristic point. According to one embodiment of the present invention, a cryogenic refrigerator includes an expander motor including a motor rotation shaft, a displacer coupled to the motor rotation shaft so as to reciprocate linearly by rotation of the motor rotation shaft, the displacer changing a volume of an expansion space of a working gas by the reciprocation, a1 st angle range passing through