A cryocooler compressor includes a control panel, and a compressor casing that includes a front panel and accommodates the control panel, in which the front panel includes a first panel portion that provides a pipe connection, and a second panel portion that is removably connected to the first panel portion and on which the control panel is mounted.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2023-101013, filed on Jun. 20, 2023, which is incorporated by reference herein in its entirety.

BACKGROUND

Technical Field

A certain embodiment of the present invention relates to a cryocooler compressor.

Description of Related Art

In general, a cryocooler such as a Gifford-McMahon (GM) cryocooler includes a compressor of a refrigerant gas to supply a high-pressure refrigerant gas to a cold head. The compressor includes components such as a compressor main body, an oil separator, an adsorber, a storage tank, and a control device.

SUMMARY

According to an embodiment of the present invention, there is provided a cryocooler compressor including a control panel, and a compressor casing that includes a front panel and accommodates the control panel, in which the front panel includes a first panel portion that provides a pipe connection, and a second panel portion that is removably connected to the first panel portion and on which the control panel is mounted.

DETAILED DESCRIPTION

In an existing cryocooler compressor, a pipe for supplying a refrigerant gas to a cold head and a pipe for collecting the refrigerant gas from the cold head can be connected to a front panel of a compressor casing. In addition, a pipe for supplying a coolant to a heat exchanger installed in the compressor casing to cool the compressor and a pipe for collecting the coolant from the heat exchanger can also be connected to the front panel. A control panel of the compressor can be disposed behind the front panel in the compressor casing.

In the compressor with such a casing design, when a worker removes the control panel, the worker first removes the front panel from the compressor casing. However, in order to remove the front panel, it is necessary to discharge the refrigerant gas from the pipe for the refrigerant gas and to discharge the coolant from the pipe for the coolant, and then to remove these pipes from the front panel. In addition, another compressor component such as an adsorber may be fastened to the front panel, and in this case, it is necessary to remove the other compressor component beforehand from the front panel. Therefore, in the existing design, the work of removing the control panel from the compressor requires a preliminary process such as disassembling the compressor into individual parts, which is quite laborious.

It is desirable to facilitate work of removing a control panel in a cryocooler compressor.

Hereinafter, an embodiment for carrying out the present invention will be described in detail with reference to the drawings. In the description and the drawings, the same or equivalent components, members, and processes are denoted by the same reference numerals, and overlapping description is omitted as appropriate. The scale and the shape of each of parts shown in the drawings are set for convenience to make the description easy to understand, and are not to be interpreted as limiting unless stated otherwise. The embodiment is merely an example and does not limit the scope of the present invention. All features described in the embodiment or combinations thereof are not necessarily essential to the present invention.

FIG.1is a diagram schematically showing a cryocooler10according to the embodiment. The cryocooler10is used to provide cryogenic cooling to an object or a medium. For example, the cryocooler10may be used as a cooling source for a superconducting magnet device. The superconducting magnet device is mounted on, for example, a high magnetic field using device as a magnetic field source of an accelerator such as a single crystal pulling device, a nuclear magnetic resonance (NMR) system, a magnetic resonance imaging (MRI) system, and a cyclotron, a high energy physical system such as a nuclear fusion system, or other high magnetic field using devices (not shown) and can generate a high magnetic field required for the devices.

The cryocooler10includes a compressor12and a cold head14. The compressor12is configured to collect a refrigerant gas of the cryocooler10from the cold head14, to pressurize the collected refrigerant gas, and to supply the refrigerant gas to the cold head14again. The compressor12is also referred to as a compressor unit. The cold head14is also referred to as an expander and includes a room temperature section14aand a low-temperature section14bwhich is also referred to as a cooling stage. The refrigerant gas is also referred to as a working gas, and other suitable gases may be used although a helium gas is typically used. The compressor12and the cold head14constitute a refrigeration cycle of the cryocooler10, whereby the low-temperature section14bis cooled to a desired cryogenic temperature. The low-temperature section14bcan cool an object to be cooled such as a superconducting magnet.

Although the cryocooler10is, for example, a single-stage or two-stage Gifford-McMahon (GM) cryocooler, the cryocooler10may be a pulse tube cryocooler, a Stirling cryocooler, or other types of cryocoolers. Although the cold head14has a different configuration depending on the type of the cryocooler10, the compressor12can use a configuration described below regardless of the type of the cryocooler10.

In general, both a pressure of a refrigerant gas supplied from the compressor12to the cold head14and a pressure of a refrigerant gas collected from the cold head14to the compressor12are considerably higher than the atmospheric pressure, and can be called a first high pressure and a second high pressure, respectively. For convenience of description, the first high pressure and the second high pressure are also simply called a high pressure and a low pressure, respectively. Typically, the high pressure is, for example, 2 to 3 MPa. The low pressure is, for example, 0.5 to 1.5 MPa and is, for example, about 0.8 MPa.

The compressor12is an oil-lubricated cryocooler compressor, and includes a compressor main body16, a refrigerant gas line18, and an oil circulation line20. InFIG.1, in order to facilitate understanding, the refrigerant gas line18is shown by a solid line, and the oil circulation line20is shown by a broken line. In addition, the compressor12includes a compressor casing24that accommodates each component of the compressor12, such as the compressor main body16, the refrigerant gas line18, and the oil circulation line20.

The compressor main body16is configured to internally compress a refrigerant gas sucked from a suction port of the compressor main body16and to discharge the refrigerant gas from a discharge port. An oil is used in the compressor main body16for the sake of cooling and lubrication, and the sucked refrigerant gas is directly exposed to the oil in the compressor main body16. Accordingly, the refrigerant gas is delivered from the discharge port in a state where the oil is slightly mixed.

The compressor main body16may be, for example, a scroll type pump, a rotary type pump, or other pumps that pressurize a refrigerant gas. The compressor main body16may be configured to discharge the refrigerant gas at a fixed and constant flow rate. Alternatively, the compressor main body16may be configured to vary the flow rate of the refrigerant gas to be discharged. The compressor main body16may be called a compression capsule.

The refrigerant gas line18includes a discharge port30, a suction port31, a discharge flow path32, and a suction flow path33. The discharge port30is an outlet of a refrigerant gas that is installed in the compressor casing24in order to deliver the refrigerant gas, which is pressurized to a high pressure by the compressor main body16, from the compressor12, and the suction port31is an inlet of the refrigerant gas that is installed in the compressor casing24in order for the compressor12to receive a low-pressure refrigerant gas. The compressor casing24accommodates the discharge flow path32and the suction flow path33. The discharge port of the compressor main body16is connected to the discharge port30by the discharge flow path32, and the suction port31is connected to the suction port of the compressor main body16by the suction flow path33.

The refrigerant gas line18is connected to the cold head14. A high-pressure port40and a low-pressure port41are provided in the room temperature section14aof the cold head14. The high-pressure port40is connected to the discharge port30by a high-pressure pipe42, and the low-pressure port41is connected to the suction port31by a low-pressure pipe43.

The oil separator34and the adsorber35are provided in the discharge flow path32. The oil separator34is provided in order to separate an oil, which is mixed in a refrigerant gas as passing through the compressor main body16, out from the refrigerant gas. The adsorber35is provided in order to remove, for example, a vaporized oil and other contaminants remaining in the refrigerant gas from the refrigerant gas through adsorption. The oil separator34and the adsorber35are connected in series. In the discharge flow path32, the oil separator34is disposed on the compressor main body16side, and the adsorber35is disposed on the discharge port30side.

An oil return line21that connects the oil separator34to the compressor main body16is provided. An oil collected by the oil separator34can be returned to the compressor main body16through the oil return line21. In the middle of the oil return line21, a filter that removes dust included in the oil separated out by the oil separator34and an orifice that controls the amount of the oil returning to the compressor main body16may be provided.

On the other hand, a storage tank36is provided at the suction flow path33. The storage tank36is provided as a volume for removing pulsation included in a low-pressure refrigerant gas returning from the cold head14to the compressor12.

In addition, a bypass valve38that connects the discharge flow path32to the suction flow path33to bypass the compressor main body16is provided at the refrigerant gas line18. For example, the bypass valve38branches off from the discharge flow path32between the oil separator34and the adsorber35and is connected to the suction flow path33between the compressor main body16and the storage tank36. The bypass valve38is provided in order to control a flow rate of a refrigerant gas and/or in order to equalize the discharge flow path32and the suction flow path33when the compressor12is stopped.

The oil circulation line20connects an oil outlet to an oil inlet of the compressor main body16in order to return the oil flowing out from the compressor main body16to the compressor main body16again. The oil circulation line20may be provided with an orifice that controls a flow rate of an oil flowing therein. In addition, a filter that removes dust included in the oil may be provided at the oil circulation line20.

In addition, the compressor12further includes a heat exchanger22that is accommodated in the compressor casing24and cools the compressor12. The heat exchanger22includes a refrigerant gas cooler22athat cools the refrigerant gas line18through heat exchange between the refrigerant gas and a cooling medium, and an oil cooler22bthat cools the oil circulation line20through heat exchange between the oil and the cooling medium.

The refrigerant gas cooler22ais disposed between the compressor main body16and the oil separator34in the discharge flow path32, and cools a high-pressure refrigerant gas heated by compression heat generated with the compression of the refrigerant gas in the compressor main body16. The refrigerant gas cooler22acools the refrigerant gas through heat exchange between the refrigerant gas and the cooling medium. The cooled refrigerant gas is purified by the oil separator34and the adsorber35. In addition, the oil cooler22bcools the oil through heat exchange between the oil flowing out from the oil outlet of the compressor main body16to the oil circulation line20and the cooling medium. The cooled oil is returned into the compressor main body16from the oil inlet of the compressor main body16. The cooling medium is supplied from the outside to the compressor12through a cooling medium intake44, and is discharged to the outside of the compressor12from a cooling medium discharge port45via the refrigerant gas cooler22aand the oil cooler22b. The cooling medium may be a coolant, for example, water. In this manner, compression heat generated by the compressor main body16is removed to the outside of the compressor12together with the cooling medium. The cooling medium may be cooled by, for example, a chiller (not shown) and may be supplied again.

In this embodiment, the heat exchanger22is a double pipe-type heat exchanger. Therefore, the heat exchanger22includes an outer tube and an inner tube inserted into the outer tube. The cooling medium is supplied to one of the outer tube and the inner tube, a fluid to be cooled is supplied to the other. Accordingly, heat exchange between the cooling medium and the target fluid is performed, and the fluid can be cooled. For example, in the refrigerant gas cooler22a, cooling water may be supplied to the outer tube, and the refrigerant gas may be supplied to the inner tube. In the oil cooler22b, cooling water may be supplied to the outer tube, and oil may be supplied to the inner tube.

During an operation of the cryocooler10, a refrigerant gas is supplied from the compressor12to the cold head14, a refrigeration cycle (for example, a GM cycle) is configured by a periodic volume fluctuation of an expansion space of the refrigerant gas in the cold head14and a pressure fluctuation of the refrigerant gas in the expansion space synchronized with the periodic volume fluctuation, and the low-temperature section14bof the cold head14is cooled to a desired cryogenic temperature. In a case where the cold head14is, for example, a two-stage type, a first-stage cooling stage is cooled to a first cooling temperature in a range of, for example, about 30 K to about 80 K, and a second-stage cooling stage is cooled to a second cooling temperature lower than the first cooling temperature, for example, 1 K to 20 K. The second cooling temperature may be a liquid helium temperature of about 4.2 K or a temperature lower than the liquid helium temperature.

A refrigerant gas collected from the cold head14to the compressor12flows into the suction port31of the compressor12from the low-pressure port41through the low-pressure pipe43. The refrigerant gas is collected to the suction port of the compressor main body16via the storage tank36on the suction flow path33. The refrigerant gas is compressed and pressurized by the compressor main body16. In this case, a temperature of the refrigerant gas is raised by compression heat. The refrigerant gas delivered from the discharge port of the compressor main body16is cooled by the refrigerant gas cooler22aof the heat exchanger22, and exits the compressor12from the discharge port30via the oil separator34and the adsorber35. The refrigerant gas is supplied into the cold head14via the high-pressure pipe42and the high-pressure port40.

FIG.2is a schematic perspective view showing an appearance of the compressor12according to the embodiment.FIGS.3and4are schematic perspective views showing the disposition of the devices inside the compressor12according to the embodiment.FIGS.2and3are perspective views of the compressor12seen from a front side, andFIG.4is a perspective view of the compressor12seen from a rear side.FIGS.3and4show a state in which some panels of the compressor casing24are removed in order to show the disposition of the internal devices of the compressor12.

As shown inFIG.2, the compressor casing24of the compressor12has a rectangular parallelepiped shape having six surfaces, and includes a front panel24a, a back panel24b, an upper panel24c, a bottom panel24d, and two side panels24eand24fon left and right sides. The back panel24bfaces an opposite side of the front panel24a. Between the front panel24aand the back panel24b, the upper panel24cis disposed above, the bottom panel24dis disposed below, and the side panels24eand24fare disposed on the left and right sides.

The front panel24aincludes two panel portions combined with each other to form the front panel24a, specifically, a first panel portion28and a second panel portion29. The first panel portion28provides a pipe connection, and the second panel portion29provides a user interface and an electrical connection. As will be described below with reference toFIG.5, the second panel portion29is removably connected to the first panel portion28.

The first panel portion28and the second panel portion29have a vertically elongated shape having a total length corresponding to a height of the compressor12, and are adjacent to each other in a left-right direction in front view. The first panel portion28corresponds to the right half of the front panel24a, and the second panel portion29corresponds to the left half of the front panel24a. The panel portions are thin plate-shaped members formed of a metal such as stainless steel or other appropriate materials.

As shown inFIGS.2and3, the first panel portion28is provided with the discharge port30, the suction port31, the cooling medium intake44, and the cooling medium discharge port45. In this way, the outlet and the inlet of the fluid such as the refrigerant gas in the compressor12are concentrated in the first panel portion28. The second panel portion29is not provided with such outlet and inlet of the fluid.

An operation panel25for receiving an input for controlling the cryocooler10from a user of the cryocooler10and/or for displaying information regarding the cryocooler10is provided on a front surface (surface facing the outside of the compressor casing24) of the second panel portion29.

In addition, a power breaker54and a cold head connector55are provided on the front surface of the second panel portion29. The power breaker54is connected to an external power source such as a commercial power source, whereby the cryocooler10is supplied with power. An electric wire for supplying power from the compressor12to the cold head14and for controlling the cold head14by the control panel50is connected to the cold head connector55. An electrical connection between the compressor12and the cold head14is established by the electric wire.

A main switch56is provided in the power breaker54. The main switch56is a switch for switching on and off the cryocooler10. When the main switch56is turned on, the compressor12and the cold head14are operated, and when the main switch56is turned off, the operation of the compressor12and the cold head14is stopped.

The control panel50is mounted on the second panel portion29. The control panel50is attached to a back surface (surface facing the inside of the compressor casing24) of the second panel portion29, and is accommodated in the compressor casing24. Although details will be described below, as shown by an arrow A inFIGS.3and4, the control panel50can be extracted forward from the compressor casing24together with the second panel portion29.

The control panel50is a control device that controls the compressor12. The control panel50may include a control circuit configured to receive an output from various sensors provided in the cryocooler10and to control various devices of the cryocooler10based on the sensor output. A plurality of electric components including sensors such as a temperature sensor and a pressure sensor may be accommodated in the compressor casing24. Each sensor may be connected to the control panel50by a communication cable.

The temperature sensor may include a refrigerant gas temperature sensor provided in the refrigerant gas line18, an oil temperature sensor provided in the oil circulation line20, a coolant temperature sensor provided in a coolant pipe of the heat exchanger22, a cooling temperature sensor provided in the low-temperature section14bof the cold head14, or the like.

For example, as shown inFIG.1, a first temperature sensor46is provided upstream of the heat exchanger22on the discharge flow path32of the refrigerant gas line18, and measures a temperature of the refrigerant gas flowing into the heat exchanger22from the compressor main body16. A second temperature sensor47is provided downstream of the heat exchanger22on the refrigerant gas line18, and measures a temperature of the refrigerant gas flowing into the oil separator34from the heat exchanger22. A third temperature sensor48is provided upstream of the heat exchanger22on the oil circulation line20, and measures a temperature of the oil flowing into the heat exchanger22from the compressor main body16. A fourth temperature sensor49is provided downstream of the heat exchanger22on the oil circulation line20, and measures a temperature of the oil flowing into the compressor main body16from the heat exchanger22. The temperature sensor is configured to output a signal representing the measured temperature to the control panel50. The temperature sensor may be, for example, a thermistor. The temperature sensor may be mounted on an outer surface of the pipe constituting the refrigerant gas line18and the oil circulation line20.

In addition, a first pressure sensor37amay be disposed in the discharge flow path32to measure a pressure of the refrigerant gas flowing through the discharge flow path32. The first pressure sensor37ais configured to output a first measured pressure signal PH representing the measured pressure to the control panel50. A second pressure sensor37bis disposed in the suction flow path33to measure a pressure of the refrigerant gas flowing through the suction flow path33. The second pressure sensor37bis configured to output a second measured pressure signal PL indicating the measured pressure to the control panel50.

The electric component controlled based on the sensor output may include, for example, a compressor motor that drives the compressor main body16, the bypass valve38, and a cold head motor that drives the cold head14. The control panel50may include a compressor inverter for controlling a rotation speed of the compressor motor and/or a cold head inverter for controlling a rotation speed of the cold head motor.

Referring again toFIGS.2to4, casters52are attached to the bottom panel24din order to facilitate the movement and the transportation of the compressor12. Four casters52are respectively provided at four corners of the bottom panel24d. As shown inFIGS.3and4, in order to fix the casters52to the bottom panel24d, a caster fixation portion52ais provided at an upper surface end portion of the bottom panel24dfor each of the casters52. As an example, the caster fixation portion52amay include a nut for fixing the caster52to the bottom panel24d. The caster52is provided with a bolt portion extending upward from the caster52, and the bolt portion extends above the bottom panel24dthrough a receiving hole penetrating the bottom panel24dand is fixed to the bottom panel24dby the nut.

As shown inFIGS.3and4, the compressor casing24includes a frame structure26that supports the above-described panels and is responsible for structural strength. The panels are removably attached to the frame structure26. In a state where the panels are attached to the frame structure26, the devices inside the compressor12are covered and hidden by the panels as shown inFIG.2. The panels may be attached to the frame structure26by an appropriate method such as screwing. In a state where the panels are removed from the frame structure26, the user or the worker can easily access the devices inside the compressor12from an opening portion of the frame structure26, and can efficiently perform maintenance work or manufacturing work of the compressor12.

For example, on a back surface of the compressor casing24, a rectangular back outer frame26athat is provided to surround the back surface and that configures a part of the frame structure26is provided. Each of four sides of the rectangular shape of the back panel24bis removably attached to the back outer frame26a. Both ends of an upper part of the back outer frame26aare connected to both ends of an upper edge of the front panel24aby two side frames26b, and a lower part of the back outer frame26ais connected to a rear edge of the bottom panel24d. In addition, a lower edge of the front panel24ais connected to a front edge of the bottom panel24d. Four sides of the upper panel24care removably attached to upper parts of the back outer frame26aand the front panel24aand the two side frames26b. Four sides of the side panel24eare removably attached to side portions of the back outer frame26aand the first panel portion28, the side frame26b, and the bottom panel24d. Four sides of the side panel24fare removably attached to side portions of the back outer frame26aand the second panel portion29, the side frame26b, and the bottom panel24d.

In the existing compressor, a design is adopted in which a panel itself forming each surface of the compressor casing is responsible for structural strength, so that a plate thickness of the panel is large, and a weight thereof tends to be large. Therefore, the work of attaching the panel in the manufacturing process or the work of removing the panel in the maintenance work is not easy, which is one of causes of a decrease in workability for the worker. On the other hand, according to the embodiment, the compressor casing24includes the frame structure26that is responsible for structural strength, so that each panel such as the back panel24battached to the frame structure26can be thinned and weight-saved. Such a casing structure is also useful in improving workability.

As described above, the main components of the compressor12, such as the compressor main body16, the heat exchanger22, the oil separator34, the adsorber35, the storage tank36, and the control panel50, are accommodated in the compressor casing24. The oil separator34, the adsorber35, and the storage tank36are installed on the bottom panel24dclose to one side panel24e, and are disposed in the compressor casing24. The adsorber35, the storage tank36, and the oil separator34are arranged in this order from the first panel portion28of the front panel24atoward the back panel24b. In addition, the compressor main body16and the control panel50are disposed in the compressor casing24close to the other side panel24f. As described above, the control panel50is attached to the second panel portion29of the front panel24a, and the compressor main body16is installed on the bottom panel24dbetween the control panel50and the back panel24b.

As shown inFIG.4, the heat exchanger22is disposed in a state of being bent in a spiral shape along the back surface of the compressor casing24. Accordingly, the double pipe of the heat exchanger22having a relatively long total length can be made compact and disposed in a space-saving manner. In addition, the spiral shape of the heat exchanger22is formed to leave a space at a center portion of the back surface of the compressor casing24. That is, an internal access opening portion62in which the heat exchanger22is not disposed is formed in the center portion of the back surface of the compressor casing24. In the manufacturing process of the compressor12or in maintenance work of the compressor12at a site where the compressor12is used, the worker can easily access the devices inside the compressor12from the internal access opening portion62. For example, the manufacturing work such as pipe welding and joint fastening and various kinds of maintenance work (for example, replacement of consumables such as filters and replacement and repair of devices such as failed sensors) can be performed through the internal access opening portion62.

FIG.5is a plan view schematically showing a part of the front panel24aaccording to the embodiment. In addition,FIG.6is a side view schematically showing a part of the front panel24aaccording to the embodiment.

As described above, the front panel24aincludes the first panel portion28and the second panel portion29that are removably connected to each other.FIG.5shows a back surface upper part of these two panel portions.FIG.5shows a state in which the remaining portions of the compressor casing24, such as the frame structure26and the upper panel24c, are removed from the front panel24a, and the control panel50is removed from the second panel portion29.

The first panel portion28and the second panel portion29are removably connected to each other by a connecting tool58. For example, the connecting tool58may be a screw, a fastening part such as a bolt and a nut, or other appropriate removable connecting parts. The first panel portion28includes a first panel side surface28aand a second panel side surface28b, and the second panel portion29includes a first panel side surface29aand a second panel side surface29b. The first panel side surface28aof the first panel portion28and the first panel side surface29aof the second panel portion29are in contact with each other and are connected to each other by the connecting tool58. In this embodiment, since the first panel portion28and the second panel portion29have a vertically elongated shape, the first panel portion28and the second panel portion29may be connected to each other by a plurality of the connecting tools58, for example, three connecting tools58along a longitudinal direction thereof.

The second panel side surface28bof the first panel portion28is a side surface on a side opposite to the first panel side surface28a, and faces the side panel24eside shown inFIG.2. The second panel side surface29bof the second panel portion29is a side surface on a side opposite to the first panel side surface29a, and faces the side panel24fside shown inFIG.2.

The first panel portion28includes an opening portion60for enabling access to the connecting tool58from the outside of the compressor casing24. Specifically, the opening portion60is provided on the second panel side surface28bof the first panel portion28. A plurality of the opening portions60may be provided on the second panel side surface28bto correspond to the plurality of connecting tools58. Since the connecting tool58and the opening portion60are provided at the same position in the longitudinal direction (that is, a height direction) of the panel, the opening portion60functions as a peephole, so to speak.

FIG.6shows the opening portion60and the vicinity thereof in the second panel side surface28bof the first panel portion28. When peeping through the opening portion60from the outside of the compressor casing24, as shown in the figure, the connecting tool58can be visually recognized in the opening portion60. In this example, a diameter of the opening portion60is slightly larger than a diameter of the connecting tool58, and the entire head portion of the connecting tool58is visible through the opening portion60.

Therefore, it is possible to access the connecting tool58from the outside of the compressor casing24by using the opening portion60. As shown inFIG.5, a tool64having a length compatible with a width (dimension in the horizontal direction inFIG.5) of the first panel portion28can be inserted from the opening portion60into the compressor casing24and can reach the connecting tool58. In a case where the connecting tool58is a screw, the tool64may be, for example, a driver. In this way, the connecting tool58can be operated by using the opening portion60and the tool64to connect or disconnect the first panel portion28and the second panel portion29.

As described above, the compressor12includes various electric components such as various sensors (for example, the pressure sensors37aand37band the temperature sensors46to49) and the bypass valve38. The electric component is accommodated in the compressor casing24and is connected to the control panel50. As shown inFIGS.4and7, the control panel50includes a plurality of connectors66in order to electrically connect the electric component and the control panel50to each other. A connector of an electric wire (not shown) extending from the electric component is connected to the connectors66.

FIG.7is a schematic plan view showing a back surface of the control panel50according to the embodiment. Referring toFIGS.4and7, the plurality of connectors66are provided on the back surface of the control panel50. These connectors may be collectively disposed at a specific location on the back surface of the control panel50. For example, as shown in the figure, a large number of the connectors66may be collectively disposed at a location near the outside of the compressor casing24(for example, a location close to the panel of the compressor casing24) on the back surface of the control panel50. In this way, the connectors66are exposed near the opening portion of the frame structure26when the panel (for example, the side panel24f) is removed from the compressor casing24. The worker can easily access the connectors66from the outside of the compressor casing24, and can easily perform the work of connecting (or removing) the electric component to (or from) the connectors66.

In addition, as shown in the figure, a large number of fasteners68(for example, tie anchors) for removably fixing electric wires for connecting the electric component to the connectors66to the control panel50are provided on the back surface of the control panel50. The fasteners68are provided on the back surface of the control panel50to define a wiring route70(an example is shown by a broken line inFIG.7). By using the fasteners68, the electric wires can be organized and disposed on the back surface of the control panel50.

FIG.8is a schematic top view showing a passage region72of the control panel50according to the embodiment. As described above, the control panel50can be extracted forward from the compressor casing24together with the second panel portion29. When the control panel50is extracted, the control panel50is extracted forward from the compressor casing24along an arrow A. In addition, inFIG.8, the components of the compressor12other than the control panel50are not shown.

The caster fixation portion52ais provided at an upper surface end portion of the bottom panel24dof the compressor casing24. In this embodiment, the passage region72of the control panel50when the control panel50is extracted forward from the compressor casing24together with the second panel portion29is defined inside the caster fixation portion52a. In other words, a width (dimension in the horizontal direction) W1of the bottom surface of the control panel50is narrower than a width W2of the second panel portion29. Accordingly, when the control panel50is extracted forward, interference between the control panel50and the caster fixation portion52acan be avoided, and the control panel50can be smoothly extracted.

An exemplary procedure for removing the compressor12from the control panel50according to the embodiment is as follows. First, the side panels24eand24fand the upper panel24care removed from the compressor casing24. The fastening between the second panel portion29of the front panel24a, and the frame structure26and the bottom panel24dis released. The tool64, which is long, such as a driver is inserted through the opening portion60of the first panel portion28of the front panel24a, the connecting tool58is removed, and the fastening between the first panel portion28and the second panel portion29is released. In this way, the structural connection between the compressor12and the control panel50is released.

The main components of the compressor12, such as the compressor main body16, the oil separator34, the adsorber35, and the storage tank36, which are installed on the bottom panel24d, do not need to be removed.

Next, the electrical connection between the compressor12and the control panel50is released. The electric wires connected to a large number of the connectors66on the back surface of the control panel50are removed. The wires are also removed from the fasteners68on the back surface of the control panel50. In addition, an electric cable connecting the compressor main body16and the control panel50is also removed.

Then, the second panel portion29and the control panel50are pulled out from the compressor casing24along an arrow A. In this way, the control panel50can be removed from the compressor12together with the second panel portion29. The removed control panel50can be subjected to the maintenance work such as repair or replacement.

As described at the beginning of the present specification, typically, in the existing compressor for the cryocooler, a single panel is used on the front surface of the compressor casing. A pipe for supplying the refrigerant gas to the cold head and a pipe for collecting the refrigerant gas from the cold head can be connected to the single front panel. In addition, a pipe for supplying the coolant to the heat exchanger installed in the compressor casing to cool the compressor and a pipe for collecting the coolant from the heat exchanger can also be connected to the front panel. The control panel of the compressor can be disposed behind the front panel in the compressor casing. In the compressor with such a design, when the worker removes the control panel, the worker first removes the front panel from the compressor casing. However, in order to remove the front panel, it is necessary to discharge the refrigerant gas from the pipe for the refrigerant gas and to discharge the coolant from the pipe for the coolant, and then to remove these pipes from the front panel. In addition, another compressor component such as an adsorber may be fastened to the front panel, and in this case, it is necessary to remove the other compressor component beforehand from the front panel. Therefore, in the existing design, the work of removing the control panel from the compressor requires a preliminary process such as disassembling the compressor into individual parts, which is quite laborious.

On the other hand, according to the embodiment, the first panel portion28of the front panel24aprovides the pipe connection, and the control panel50is mounted on the second panel portion29. Accordingly, the second panel portion29can be removed without removing the first panel portion28from the compressor casing24in a state where the pipes for the refrigerant gas and the coolant are connected to the first panel portion28. It is possible to eliminate the need to remove the pipes in the work of removing the control panel50. It is possible to facilitate the work of removing the control panel50in the compressor12for the cryocooler10.

In addition, the first panel portion28is provided with the opening portion60for enabling access to the connecting tool58from the outside of the compressor casing24. Accordingly, without removing various devices such as the adsorber35installed in the compressor casing24, the tool64can reach the connecting tool58from the outside of the compressor casing24, and the connection between the first panel portion28and the second panel portion29can be released. This is also useful to facilitate the work of removing the control panel50.

The plurality of connectors66connected to the plurality of electric components are provided on the back surface of the control panel50. Preferably, the plurality of connectors66are collectively disposed at a specific location on the back surface of the control panel50. Accordingly, the connection between the control panel50and the electric component can be released by removing the wires from the connectors66.

In addition, the control panel50can be extracted forward from the compressor casing24together with the second panel portion29. The passage region72of the control panel50is defined inside the caster fixation portion52a. Accordingly, the control panel50can be extracted forward without interfering with the caster fixation portion52a.

The present invention has been described above based on the examples. It will be understood by those skilled in the art that the present invention is not limited to the embodiment, various modification examples are possible, and such modification examples are also within the scope of the present invention. Various features described concerning a certain embodiment are also applicable to other embodiments. A new embodiment resulting from combinations also has the effects of each of the combined embodiments.

In the above-described embodiment, the front panel24ais formed of two panel portions that are adjacent to each other in the left-right direction, but the front panel24amay have another configuration. For example, the front panel24amay be formed of two panel portions that are adjacent to each other in an up-down direction. In this case, the first panel portion28and the second panel portion29may have a horizontally elongated shape having a total length corresponding to a width of the compressor12, and may be adjacent to each other in the up-down direction in front view. The first panel portion28(or the second panel portion29) may correspond to the upper half of the front panel24a, and the second panel portion29(or the first panel portion28) may correspond to the lower half of the front panel24a.

The front panel24amay be divided into three or more panel portions including the first panel portion28and the second panel portion29. The panel portions may be connected to each other to form the front panel24a.

Although the present invention has been described using specific words and phrases based on the embodiment, the embodiment merely shows one aspect of the principle and application of the present invention, and various modifications and improvements can be made within the scope of the present invention described in claims.