COMPRESSOR FOR CRYOCOOLER AND COMPRESSOR CASING FOR CRYOCOOLER

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2024-185342, filed on October 21, 2024, which is incorporated by reference herein in its entirety.

BACKGROUND

Technical Field

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

Description of Related Art

For example, a cryocooler can be used for cryogenic cooling of a measurement element in measurement devices in various fields, such as a superconducting single photon detector, a gravitational wave detector, and a voltage standard. In this case, the cryocooler includes a cold head that cools the measurement element and a compressor that supplies and discharges a refrigerant gas such as a helium gas to and from the cold head. Heat absorbed by the cold head is dissipated from the compressor.

SUMMARY

According to an embodiment of the present invention, there is provided a compressor for a cryocooler, including a compressor casing including a front surface; and a surface including an intake port and different from the front surface. An air inlet for the intake port is provided on an edge of the front surface. The compressor further includes an airflow generator disposed inside the compressor casing to generate an airflow into the compressor casing from the air inlet through the intake port.

According to an embodiment of the present invention, there is provided a compressor for a cryocooler, including a compressor casing, and a compressor component disposed inside the compressor casing to generate vibration and/or heat during an operation. The compressor casing includes a support plate supporting the compressor component and supported on a bottom surface of the compressor casing via a vibration isolation mount. The vibration isolation mount is disposed outside the support plate in a top view.

According to an embodiment of the present invention, there is provided a compressor casing for a cryocooler, including a front surface, and a surface including an intake port and different from the front surface, in which an air inlet for the intake port is provided on an edge of the front surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically showing a cryocooler according to an embodiment.

FIG. 2 is a view schematically showing an appearance of a compressor unit of the cryocooler according to the embodiment.

FIG. 3 is a view schematically showing the appearance of the compressor unit of the cryocooler according to the embodiment.

FIG. 4 is a view schematically showing the appearance of the compressor unit of the cryocooler according to the embodiment.

FIG. 5 is a view schematically showing the appearance of the compressor unit of the cryocooler according to the embodiment.

FIG. 6 is a view schematically showing an inside of the compressor unit of the cryocooler according to the embodiment.

FIG. 7 is a view schematically showing the inside of the compressor unit of the cryocooler according to the embodiment.

FIG. 8 is a view schematically showing the inside of the compressor unit of the cryocooler according to the embodiment.

DETAILED DESCRIPTION

The measurement device as described above may include multiple configuration devices such as a cryostat equipped with a cryocooler, a power source, a detector, and a vacuum pump. When a footprint is required for each configuration device for installation, a considerably wide installation space may be required to install a set of the measurement devices. In addition, when the measurement device is installed or moved, an electric wire and a gas pipe are removed from each of the configuration devices, and the configuration devices are packed. Each of the packed configuration devices is unpacked at a site, and the configuration devices are connected to each other again by the electric wire and the gas pipe. Consequently, a relatively heavy load is imposed on a worker. The present inventor proposes to integrate the configuration devices of the measurement device in a rack. A footprint of the measurement device can be reduced by storing the configuration device in a storage shelf of the rack. In addition, the measurement device can be easily installed or moved by carrying the measurement device together with the rack.

However, the present inventor has recognized that the measurement device may have constraints on heat dissipation from a compressor for the cryocooler. The reason is as follows. The compressor needs to be downsized to be accommodated in the rack, and is surrounded by a casing such as a wall or a floor of the rack. These configurations may hinder the heat dissipation. In particular, when the compressor is an air-cooled type, a direction and a location of air intake and exhaust may be restricted, and influence on heat dissipation capacity may be remarkable. Degradation in the heat dissipation capacity from the compressor is undesirable since the degradation may cause degraded performance and a shortened lifespan of the cryocooler.

It is desirable to efficiently cool a compressor for a cryocooler.

Hereinafter, an embodiment for carrying out the present invention will be described in detail with reference to the drawings. The same reference numerals will be assigned to the same or equivalent components, members, and processes in the description and the drawings, and repeated description will be appropriately omitted. A scale or a shape of each shown element is set for convenience in order to facilitate the description, and is not to be interpreted in a limited manner unless otherwise specified. The embodiments are merely examples, and do not limit the scope of the present invention at all. All features described in the embodiments or combinations thereof are not necessarily essential to the present invention.

FIG. 1 is a view schematically showing a cryocooler according to the embodiment. A cryocooler 10 is used to provide cryogenic cooling for an object or a medium. For example, the cryocooler 10 may be used as a cooling source of a measurement device. For example, the measurement device may be a superconducting single photon detector, a gravitational wave detector, a voltage standard, or the like, in various fields.

The cryocooler 10 includes a compressor 12 and a cold head 14. The compressor 12 is configured to collect a refrigerant gas of the cryocooler 10 from the cold head 14, to pressurize the collected refrigerant gas, and to supply the refrigerant gas to the cold head 14 again. The compressor 12 may be referred to as a compressor unit. The cold head 14 may be referred to as an expander, and includes a room temperature section 14a and a low-temperature section 14b which may be referred to as a cooling stage. The refrigerant gas may be referred to as a working gas, and other suitable gases may also be used although a helium gas is typically used. The compressor 12 and the cold head 14 configure a refrigeration cycle of the cryocooler 10. In this manner, the low-temperature section 14b is cooled to a desired cryogenic temperature. The low-temperature section 14b can cool an object to be cooled, such as a measurement element in the measurement device.

As an example, the cryocooler 10 is a single-stage or two-stage Gifford-McMahon (GM) cryocooler. Meanwhile, the cryocooler 10 may also be a pulse tube cryocooler, a Stirling cryocooler, or another type of cryocooler. Although a configuration of the cold head 14 differs depending on a type of the cryocooler 10, the compressor 12 can adopt a configuration described below regardless of the type of the cryocooler 10.

In general, both a pressure of a refrigerant gas supplied from the compressor 12 to the cold head 14 and a pressure of a refrigerant gas collected from the cold head 14 to the compressor 12 are considerably higher than atmospheric pressure, and can be referred to as a first high pressure and a second high pressure, respectively. For convenience of description, the first high pressure and the second high pressure are simply referred to as a high pressure and a low pressure, respectively. Typically, the high pressure is 2 to 3 MPa, for example. For example, the low pressure is 0.5 to 1.5 MPa, and is approximately 0.8 MPa, for example.

The compressor 12 is a compressor for an oil-lubricated cryocooler, and includes a compressor body 16, a refrigerant gas line 18, and an oil circulation line 20. In FIG. 1, in order to facilitate understanding, the refrigerant gas line 18 is shown by a solid line, and the oil circulation line 20 is shown by a broken line. In addition, the compressor 12 includes a compressor casing 24 that accommodates each component of the compressor 12, such as the compressor body 16, the refrigerant gas line 18, and the oil circulation line 20.

The compressor body 16 is configured to internally compress the refrigerant gas suctioned through a suction port of the compressor body 16 and to discharge the refrigerant gas through a discharge port. Oil is used for cooling and lubrication in the compressor body 16, and the suctioned refrigerant gas is directly exposed to the oil inside the compressor body 16. Accordingly, the refrigerant gas is delivered through the discharge port in a state of being slightly mixed with the oil.

For example, the compressor body 16 may be a scroll type pump, a rotary type pump, or another pump that pressurizes the refrigerant gas. The compressor body 16 may be configured to discharge the refrigerant gas at a fixed and constant flow rate. Alternatively, the compressor body 16 may be configured such that a flow rate of the discharged refrigerant gas is variable. The compressor body 16 may be referred to as a compression capsule.

The refrigerant gas line 18 includes a discharge port 30, a suction port 31, a discharge flow path 32, and a suction flow path 33. The discharge port 30 is an outlet of the refrigerant gas which is installed in the compressor casing 24 to deliver the refrigerant gas pressurized to a high pressure by the compressor body 16 from the compressor 12, and the suction port 31 is an inlet of the refrigerant gas which is installed in the compressor casing 24 in order for the compressor 12 to receive a low-pressure refrigerant gas. The compressor casing 24 accommodates the discharge flow path 32 and the suction flow path 33. The discharge port of the compressor body 16 is connected to the discharge port 30 by the discharge flow path 32, and the suction port 31 is connected to the suction port of the compressor body 16 by the suction flow path 33.

The refrigerant gas line 18 is connected to the cold head 14. The room temperature section 14a of the cold head 14 is provided with a high-pressure port 40 and a low-pressure port 41. The high-pressure port 40 is connected to the discharge port 30 by a high-pressure pipe 42, and the low-pressure port 41 is connected to the suction port 31 by a low-pressure pipe 43.

The discharge flow path 32 is provided with an oil separator 34 and an adsorber 35. The oil separator 34 is provided to separate oil mixed with the refrigerant gas from the refrigerant gas when the oil passes through the compressor body 16. For example, the adsorber 35 is provided to remove vaporized oil and other contaminants which remain in the refrigerant gas from the refrigerant gas through adsorption. The oil separator 34 and the adsorber 35 are connected in series. In the discharge flow path 32, the oil separator 34 is disposed on the compressor body 16 side, and the adsorber 35 is disposed on the discharge port 30 side.

Meanwhile, the suction flow path 33 is provided with a storage tank 36. The storage tank 36 is provided to have a volume for removal of pulsation included in a low-pressure refrigerant gas returning from the cold head 14 to the compressor 12.

In addition, a bypass valve 38 that connects the discharge flow path 32 to the suction flow path 33 to bypass the compressor body 16 is provided in the refrigerant gas line 18. For example, the bypass valve 38 branches off from the discharge flow path 32 at a position between the oil separator 34 and the adsorber 35, and is connected to the suction flow path 33 at a position between the compressor body 16 and the storage tank 36. The bypass valve 38 is provided to control a flow rate of the refrigerant gas and/or to equalize the pressure in the discharge flow path 32 and the pressure in the suction flow path 33 when the compressor 12 is stopped.

The oil circulation line 20 connects an oil outlet to an oil inlet of the compressor body 16 to return the oil flowing out from the compressor body 16 again to the compressor body 16. The oil circulation line 20 may be provided with an orifice that controls a flow rate of the oil flowing in the oil circulation line 20. In addition, the oil circulation line 20 may be provided with a filter that removes dust contained in the oil.

In addition, an oil return line 21 that connects the oil separator 34 to the compressor body 16 is provided. The oil collected by the oil separator 34 can be returned to the compressor body 16 through the oil return line 21. In an intermediate portion of the oil return line 21, a filter that removes dust contained in the oil separated by the oil separator 34 and an orifice that controls the amount of the oil returning to the compressor body 16 may be provided.

In addition, the compressor 12 includes a control panel 39. The control panel 39 is mounted on the compressor 12 as a control device that controls the cryocooler 10. The control panel 39 may include a control circuit configured to receive outputs from various sensors provided in the cryocooler 10 and to control various devices of the cryocooler 10, based on a sensor output. A plurality of electrical components including the sensors may be accommodated in the compressor casing 24 together with the control panel 39. Each sensor may be connected to the control panel 39 by a communication cable. For example, the electrical components controlled based on the sensor output may include a compressor motor 17 that drives the compressor body 16, a bypass valve 38, and a cold head motor that drives the cold head 14.

Various sensors such as pressure sensors and temperature sensors may be provided in the compressor 12 to identify a state of the compressor 12. For example, a first pressure sensor 37a may be disposed in the discharge flow path 32 to measure a pressure of the refrigerant gas flowing through the discharge flow path 32. The first pressure sensor 37a is configured to output a first measured pressure signal PH indicating a measured pressure to the control panel 39. In addition, a second pressure sensor 37b may be disposed in the suction flow path 33 to measure a pressure of the refrigerant gas flowing through the suction flow path 33. The second pressure sensor 37b is configured to output a second measured pressure signal PL indicating a measured pressure to the control panel 39. The temperature sensor may include a refrigerant gas temperature sensor provided in the refrigerant gas line 18, an oil temperature sensor provided in the oil circulation line 20, a cooling temperature sensor provided in the low-temperature section 14b of the cold head 14, or the like. The temperature sensor is configured to output a signal indicating a measured temperature to the control panel 39.

FIGS. 2 to 4 are views schematically showing an appearance of the compressor unit of the cryocooler according to the embodiment. In FIG. 2, a lower portion of a front surface of the compressor 12 is schematically shown. In FIG. 3, a bottom surface of the compressor 12 is schematically shown. FIG. 4 schematically shows a perspective view when the compressor 12 is viewed from below.

As shown in FIGS. 2 to 4, the compressor casing 24 includes a rectangular parallelepiped shape having six surfaces, and includes a front surface 24a, a rear surface 24b, an upper surface 24c, a bottom surface 24d, a left side surface 24e, and a right side surface 24f. The rear surface 24b faces a side opposite to the front surface 24a. Between the front surface 24a and the rear surface 24b, the upper surface 24c is disposed above, the bottom surface 24d is disposed below, and the left side surface 24e and the right side surface 24f are respectively disposed on the left side and the right side when viewed from the front surface 24a. These surfaces of the compressor casing 24 may be thin plate-shaped panel members formed of metal such as stainless steel or other appropriate materials.

The bottom surface 24d of the compressor casing 24 faces a compressor installation surface 26. When the cryocooler 10 is stored in a rack, the compressor installation surface 26 may be a shelf surface of the rack. For example, the rack may be a rack conforming to a standard such as a 19-inch rack. An object to be cooled such as the measurement device to be cooled by the cryocooler 10 may be stored in the rack together with the cryocooler 10.

When the compressor 12 is stored in the rack, the upper surface 24c, the bottom surface 24d, the left side surface 24e, and the right side surface 24f of the compressor casing 24 are covered with a shelf plate or a wall surface of the rack. On the other hand, the front surface 24a and the rear surface 24b of the compressor casing 24 are not covered with the shelf plate or the wall surface of the rack, and are easily accessible. Therefore, various user interfaces may be provided on the front surface 24a and the rear surface 24b of the compressor casing 24.

For example, a display panel that displays information relating to the cryocooler 10, such as an operation time of the cryocooler 10, a pressure gauge that indicates the pressure of the refrigerant gas supplied from the compressor 12 to the cold head 14, a refrigerant gas replenishment port for replenishing the refrigerant gas to the refrigerant gas line 18, and a main switch of the cryocooler 10 may be provided on the front surface 24a of the compressor casing 24.

The rear surface 24b of the compressor casing 24 may provide pipe connection and power source connection. For example, the discharge port 30 and the suction port 31 of the refrigerant gas line 18 may be provided on the rear surface 24b of the compressor casing 24. In addition, an input power source connector, a cold head connector, and a communication cable connector may be provided on the rear surface 24b of the compressor casing 24. The input power source connector is connected to an external power source such as a commercial power source. In this manner, power is supplied to the cryocooler 10. An electric wire for supplying the power to the cold head 14 and for controlling the cold head 14 is connected to the cold head connector. The communication cable connector is connected to an external device by a communication cable. In this manner, communication can be performed between the compressor 12 and the external device.

The compressor 12 further includes a compressor cooling system 28. In the present embodiment, the compressor cooling system 28 is configured as an air-cooled type heat exchanger, and includes an airflow generator 29 accommodated in the compressor casing 24. The compressor cooling system 28 cools the compressor 12 by heat exchange between an airflow generated inside the compressor casing 24 by the airflow generator 29 and the compressor components such as the refrigerant gas line 18 and the oil circulation line 20. The airflow generator 29 may be a cooling fan that forcibly cools the refrigerant gas line 18 and the oil circulation line 20 with the airflow.

The airflow generator 29 may be disposed to take in air from the outside of the compressor casing 24, to blow the air to the refrigerant gas line 18 and the oil circulation line 20, and to cool the refrigerant gas line 18 and the oil circulation line 20 with the air. Alternatively, the airflow generator 29 may be disposed to cool the refrigerant gas line 18 and the oil circulation line 20 by drawing the air around the refrigerant gas line 18 and the oil circulation line 20 to the outside of the compressor casing 24. In order to cool the high-pressure refrigerant gas heated by compression heat generated as a result of the compression of the refrigerant gas in the compressor body 16, the airflow generator 29 may be configured to cool the refrigerant gas line 18 in the discharge flow path 32 between the compressor body 16 and the oil separator 34.

As shown in FIGS. 1 to 4, in the embodiment, the compressor casing 24 includes an intake port 50, an air inlet 52 for the intake port 50, and an exhaust port 54. The airflow generator 29 generates the airflow into the compressor casing 24 from the air inlet 52 through the intake port 50. In FIGS. 1 and 4, in order to facilitate understanding, the airflow flowing from the air inlet 52 into the compressor casing 24 through the intake port 50 is schematically shown by an arrow 56. In addition, the airflow generator 29 discharges the airflow flowing into the compressor casing 24 from the intake port 50 to the outside of the compressor casing 24 as exhaust air from the exhaust port 54. In FIGS. 1 and 4, in order to facilitate understanding, the exhaust air is schematically shown by an arrow 58.

The intake port 50 is provided on a surface different from the front surface 24a of the compressor casing 24, in this example, on the bottom surface 24d of the compressor casing 24. The intake port 50 may be at least one opening portion that penetrates the compressor casing 24, and may be a plurality of slits or holes, for example. The intake port 50 may be provided in a partial region of a specific surface (in this example, the bottom surface 24d) of the compressor casing 24, for example, a region close to the air inlet 52 on the surface (region close to the front surface 24a on the bottom surface 24d in this example). Alternatively, the intake port 50 may be provided over the entire specific surface of the compressor casing 24. In order to form the intake port 50, at least a portion of the specific surface (in this example, the bottom surface 24d) of the compressor casing 24 may be formed of a perforated plate such as punching metal or a wire mesh, for example.

The air inlet 52 is provided in an edge of the front surface 24a of the compressor casing 24, in this example, in a lower edge of the front surface 24a. More specifically, a gap formed between the compressor installation surface 26 and the lower edge of the front surface 24a serves as the air inlet 52.

From the viewpoint of reducing wind cutting noise (to be described later), a total area of the air inlet 52 (that is, a sum of an area of the air inlet 52 in a plane along the front surface 24a of the compressor casing 24) may be narrower than a total area of the intake port 50 (that is, a sum of the area of the intake port 50 in a plane along the bottom surface 24d of the compressor casing 24). For example, the total area of the air inlet 52 may be 20% or larger and 50% or smaller of the total area of the intake port 50 in view of balance between the wind cutting noise and an airflow rate.

In order to form the air inlet 52 between the compressor installation surface 26 and the lower edge of the front surface 24a, the compressor casing 24 may include a support body 60 that supports the compressor 12 slightly upward of the compressor installation surface 26. The support body 60 may be provided on the bottom surface 24d of the compressor casing 24 to support the compressor 12 on the compressor installation surface 26.

The compressor casing 24 includes at least one guide 62 that guides the airflow from the air inlet 52 to the intake port 50. The guide 62 is provided on the bottom surface 24d of the compressor casing 24. The guide 62 may configure a portion of the support body 60.

In this example, three guides 62 extend linearly from the lower edge of the front surface 24a toward the lower edge of the rear surface 24b on the bottom surface 24d. Two guides 62 are disposed on both sides of the bottom surface 24d, and the remaining one guide 62 is disposed at the center of the bottom surface 24d. An intake passage from the air inlet 52 to the intake port 50 is formed between the two adjacent guides 62.

As shown in FIG. 1, a filter 68 may be installed at any position of the intake passage to separate dust from the airflow and to avoid the dust from entering the inside of the compressor 12.

As shown in FIG. 2, the guide 62 may configure a portion of a linear motion mechanism 64 that supports the compressor 12 to be movable with respect to the compressor installation surface 26. In the shown example, two guides 62 disposed on both sides of the bottom surface 24d serve as a portion of the linear motion mechanism 64. The linear motion mechanism 64 may be configured to linearly move the compressor 12 in a front-rear direction with respect to the compressor installation surface 26. For example, the linear motion mechanism 64 may be a slide rail including a fixed-side rail fixed to the compressor installation surface 26, and the guide 62 may be a movable-side rail fixed to the bottom surface 24d of the compressor casing 24 and supported to be movable to the fixed-side rail. In this way, when the compressor 12 is stored in the rack, the compressor 12 can be easily taken in and out of the rack by using the linear motion mechanism 64. Therefore, this configuration is advantageous.

The exhaust port 54 is provided at a location different from the front surface 24a and the bottom surface 24d of the compressor casing 24, in this example, on the rear surface 24b of the compressor casing 24. The exhaust port 54 may be at least one opening portion that penetrates the compressor casing 24, and may be a plurality of slits or holes, for example. The exhaust port 54 may be provided in at least a partial region of a specific surface (in this example, the rear surface 24b) of the compressor casing 24. In order to form the exhaust port 54, at least a portion of the specific surface of the compressor casing 24 may be formed of a perforated plate such as punching metal or a wire mesh, for example.

During an operation of the cryocooler 10, the refrigerant gas is supplied from the compressor 12 to the cold head 14, a refrigeration cycle (for example, a GM cycle) is configured to include a periodic volume fluctuation of an expansion space of the refrigerant gas inside the cold head 14 and a pressure fluctuation of the refrigerant gas in the expansion space synchronized with the periodic volume fluctuation, and the low-temperature section 14b of the cold head 14 is cooled to a desired cryogenic temperature. For example, when the cold head 14 is a two-stage type, a first cooling stage is cooled to a first cooling temperature that falls in a range of approximately 30 K to approximately 80 K, for example, and a second 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 approximately 4.2 K or a temperature lower than the liquid helium temperature.

The refrigerant gas collected from the cold head 14 by the compressor 12 flows into the suction port 31 of the compressor 12 through the low-pressure port 41 and the low-pressure pipe 43. The refrigerant gas is collected to the suction port of the compressor body 16 via the storage tank 36 on the suction flow path 33. The refrigerant gas is compressed and pressurized by the compressor body 16. The refrigerant gas delivered from the discharge port of the compressor body 16 flows out from the compressor 12 from the discharge port 30 via the oil separator 34 and the adsorber 35. The refrigerant gas is supplied into the cold head 14 via the high-pressure pipe 42 and the high-pressure port 40.

During the operation of the cryocooler 10, the airflow generator 29 is operated such that the airflow (arrow 56) flows into the compressor casing 24 from the air inlet 52 through the intake port 50. The refrigerant gas and the oil which are heated by the compression heat in the compressor body 16 are cooled by heat exchange with the airflow. The refrigerant gas is cooled by the compressor cooling system 28, and is supplied from the compressor 12 to the cold head 14. The oil is cooled by the compressor cooling system 28, and is returned to the compressor body 16. The airflow heated by heat exchange is discharged from the compressor casing 24 through the exhaust port 54 as the exhaust air (arrow 58). In this way, the compression heat generated in the compressor body 16 is discharged outward of the compressor 12 together with the airflow.

According to the embodiment, relatively low-temperature fresh air can be taken into the compressor casing 24 from a space in front of the compressor 12 through the air inlet 52 and the intake port 50. The heat dissipation from the compressor 12 can be promoted by using the airflow, and the compressor 12 can be efficiently cooled. In this manner, it is possible to suppress an excessive increase in the temperature of the compressor 12 which is caused by insufficient heat dissipation, and a degraded performance and a shortened lifespan of the cryocooler which are caused by the excessive increase in the temperature.

This cooling configuration is particularly advantageous when the compressor 12 is stored in the rack. Even when the compressor 12 is surrounded by a shelf surface or a wall surface of the rack, the front surface 24a of the compressor 12 is usually open to the space in front of the compressor 12. The low-temperature fresh air is suctioned into the compressor 12 from the front space through the air inlet 52 of the front surface 24a, and the compressor 12 can be efficiently cooled.

In addition, the disposition of the intake port 50 and the air inlet 52 according to the embodiment is effective in reducing noise generated due to the airflow. In a typical existing compressor, the intake port (multiple slits, openings, and the like) can be formed on a front surface of a casing to take in a large amount of air. In this case, the intake port can be a sound source that generates the wind cutting noise by the air passing through the intake port. The generated wind cutting noise is easily propagated from the front surface of the casing to the surrounding space, and can be sensed as the noise. However, in the embodiment, the intake port 50 is not provided on the front surface 24a of the compressor casing 24. The intake port 50 faces the compressor installation surface 26. The compressor installation surface 26 serves as a barrier, and even when the wind cutting noise is generated from the intake port 50, the wind cutting noise is less likely to be transmitted to the surroundings. Therefore, the noise can be reduced, and quietness of the compressor 12 can be improved.

In addition, as shown in FIGS. 3 and 4, the surface of the compressor casing 24 provided with the intake port 50, in this example, the bottom surface 24d of the compressor casing 24 is configured to prevent the exhaust air from flowing into the intake port 50. Therefore, a shielding member 66 is provided. The shielding member 66 is disposed to close a gap between the surface of the compressor casing 24 provided with the intake port 50 and a surface facing the surface of the compressor casing 24, in this example, a gap between the bottom surface 24d and the compressor installation surface 26.

The shielding member 66 is disposed on a side opposite to the air inlet 52 with respect to the intake port 50 on the bottom surface 24d. The shielding member 66 is provided in an edge of the rear surface 24b of the compressor casing 24, in this example, in a lower edge of the rear surface 24b. The shielding member 66 may be a shielding plate disposed in a rear end of the guide 62 to connect the guides 62 to each other.

The exhaust air flowing out from the exhaust port 54 absorbs exhaust heat of the compressor 12. Therefore, the exhaust air has a higher temperature than the airflow suctioned from the intake port 50. The shielding member 66 is used to prevent the exhaust air from flowing into the intake port 50. In this manner, it is possible to suppress an increase in the temperature which is caused by the mixing of the exhaust air into an intake flow. This configuration also contributes to efficient cooling of the compressor 12.

FIG. 5 is a view schematically showing the appearance of the compressor unit of the cryocooler according to the embodiment. FIG. 5 schematically shows a perspective view when the compressor 12 is viewed from a rear side. As shown in the drawing, the compressor 12 may include a transformer 70. The compressor 12 may be connected to an external power source via the transformer 70. The transformer 70 may be configured to convert power (for example, a voltage) from the external power source into power suitable for the compressor 12 and to supply the power to the compressor 12. The transformer 70 may be attachable to and detachable from the compressor casing 24.

The transformer 70 is disposed close to the exhaust port 54 outside the compressor casing 24. The transformer 70 may be attached to the compressor casing 24, for example, to the rear surface 24b of the compressor casing 24 to be adjacent to the exhaust port 54. In the shown example, the transformer 70 is disposed on one side (left side in the drawing) of the rear surface 24b of the compressor casing 24, and the exhaust port 54 is provided on the other side (right side in the drawing) of the rear surface 24b. In this way, the transformer 70 is disposed to be shifted from the exhaust port 54 not to hinder the flow of the exhaust air flowing out from the exhaust port 54.

During the operation of the cryocooler 10, the transformer 70 can generate a large amount of heat to have a relatively high temperature. Since the temperature of the transformer 70 can be higher than the temperature of the exhaust air, the present inventor has noticed that the exhaust air can be used to cool the transformer 70. An increase in the temperature rise of the transformer 70 can be suppressed by actively cooling the transformer 70 with the exhaust air. In this manner, deterioration of an insulating material inside the transformer 70 can be suppressed, and a lengthened lifespan of the transformer 70 can be realized.

In order to promote the cooling of the transformer 70, the transformer 70 may include an exhaust inlet 70a that takes in the exhaust air. As shown in the drawing, in order to easily take in the exhaust air, the exhaust inlet 70a may be provided on a surface of the transformer 70 adjacent to the exhaust port 54. In addition, the transformer 70 may include an exhaust discharge port 70b. The exhaust discharge port 70b may be provided on a surface different from the surface of the transformer 70 provided with the exhaust inlet 70a, in the shown example, on the rear surface of the transformer 70. The exhaust inlet 70a and the exhaust discharge port 70b may be at least one opening portion that penetrates the casing of the transformer 70, and may be a plurality of slits or holes, for example.

The exhaust inlet 70a of the transformer 70 may be connected to the exhaust port 54 of the compressor 12. For example, the exhaust inlet 70a may be connected to the exhaust port 54 via a duct. In this case, the transformer 70 may be disposed to face the exhaust port 54.

FIGS. 6 to 8 are views schematically showing the inside of the compressor unit of the cryocooler according to the embodiment. FIG. 6 schematically shows a portion of a cross section taken along line A-A shown in FIG. 3. FIG. 7 schematically shows a portion of a cross section taken along line B-B shown in FIG. 6. FIG. 8 schematically shows a portion of a cross section along line C-C shown in FIG. 7.

As shown in FIG. 6, a compressor component disposed inside the compressor casing 24 to generate the vibration and/or the heat during the operation may be supported by a support plate 72. For example, various components described above such as the compressor body 16, the airflow generator 29, and the control panel 39 can be included in these compressor components. In FIGS. 7 and 8, the compressor components are omitted in the drawing to facilitate understanding.

The support plate 72 is disposed inside the compressor casing 24 to face the bottom surface 24d of the compressor casing 24. The compressor casing 24 may have a double structure including an outer casing and an inner casing, and the support plate 72 may form a bottom surface of the inner casing. The compressor component may be disposed inside the inner casing, and the inner casing may be disposed inside the outer casing. The outer casing may include the front surface 24a, the rear surface 24b, the upper surface 24c, the bottom surface 24d, the left side surface 24e, and the right side surface 24f which are described above.

The support plate 72 is supported on the bottom surface 24d of the compressor casing 24 via a vibration isolation mount 74. As shown in FIG. 7, the vibration isolation mount 74 is disposed outside the support plate 72 in a top view. In this example, four vibration isolation mounts 74 are provided, and are disposed at four corners of the bottom surface 24d. The support plate 72 is supported on the bottom surface 24d for vibration isolation by the vibration isolation mount 74. In this manner, it is possible to suppress outward transmission of the vibration generated by the compressor component.

The compressor casing 24 includes a fixing member 76 attached to an outer periphery of the support plate 72, and the vibration isolation mount 74 is fixed to the fixing member 76. In the shown example, a pair of long fixing pieces is used as the fixing member 76. The fixing pieces are fixed to two facing sides of the support plate 72. As shown in FIG. 8, two sides of the support plate 72 may be folded back, and the fixing piece may be fixed to a folded-back portion thereof. The cross section of the support plate 72 has a so-called U-shape. The folded-back portion is also useful for increasing stiffness of the support plate 72.

As shown in FIG. 7, a length of the fixing piece is longer than a length of a side of the fixed support plate 72, and thus, both ends of the fixing piece extend to both sides of the support plate 72. Two vibration isolation mounts 74 are fixed to both ends of each of the fixing pieces. Each of the vibration isolation mounts 74 is fixed to the fixing piece by an appropriate method, for example, bolting so that a vibration isolation material such as vibration isolation rubber is pinched between the bottom surface 24d and the fixing piece.

Since the compressor component is mounted on the support plate 72, the temperature is likely to rise due to heat generation of the compressor component. Since the fixing member 76 is interposed between the support plate 72 and the vibration isolation mount 74, the fixing member 76 functions as a so-called thermal resistance. In this manner, heat conduction from the support plate 72 to the vibration isolation mount 74 can be reduced, compared to when the vibration isolation mount 74 is directly fixed to the support plate 72. An increase in the temperature of the vibration isolation mount 74 can be suppressed. In this manner, deterioration of the vibration isolation mount 74 can be suppressed, and a lengthened lifespan of the vibration isolation mount 74 can be realized.

In addition, the vibration isolation mount 74 is disposed outside the support plate 72 in a top view. Therefore, the vibration isolation mount 74 can be disposed away from the support plate 72, compared to when the vibration isolation mount 74 is disposed immediately below the support plate 72. In addition, the outside of the support plate 72 corresponds to a gap between the outer casing and the inner casing. Therefore, the outside of the support plate 72 serves as a passage for the airflow suctioned into the compressor casing 24 from the intake port 50. These configurations are also useful for suppressing an increase in the temperature of the vibration isolation mount 74.

Hitherto, the present invention has been described based on the embodiments. The present invention is not limited to the above-described embodiments. It may be understood by those skilled in the art that various design changes can be made, various modification examples can be adopted, and the modification examples also fall within the scope of the present invention. Various features described with reference to a certain embodiment are also applicable to other embodiments. A new embodiment acquired from a combination of the embodiments compatibly achieves each advantageous effect of the combined embodiments.

In the above-described embodiment, a case where the intake port 50 is provided on the bottom surface 24d of the compressor casing 24 and the air inlet 52 is provided in the lower edge of the front surface 24a of the compressor casing 24 has been described as an example. However, the intake port 50 and the air inlet 52 may be provided at another location of the compressor casing 24.

For example, the intake port 50 may be provided on the upper surface 24c of the compressor casing 24, and the air inlet 52 may be provided in an upper edge of the front surface 24a of the compressor casing 24. Alternatively, the intake port 50 may be provided on the left side surface 24e of the compressor casing 24, and the air inlet 52 may be provided in a left edge of the front surface 24a of the compressor casing 24. Alternatively, the intake port 50 may be provided on the right side surface 24f of the compressor casing 24, and the air inlet 52 may be provided in a right edge of the front surface 24a of the compressor casing 24. Similarly, the guide 62 may be provided on the surface of the compressor casing 24 provided with the intake port 50. Similarly, the shielding member 66 may be provided on the surface of the compressor casing 24 provided with the intake port 50.

When necessary, in addition to the intake port 50 provided on the other surface, an additional intake port 50 may be provided on the front surface 24a or the rear surface 24b of the compressor casing 24.

In the above-described embodiment, a case where the exhaust port 54 is provided on the rear surface 24b of the compressor casing 24 has been described as an example. However, the exhaust port 54 may be provided at another location of the compressor casing 24.

In the above-described embodiment, a case where the compressor cooling system 28 is configured as the air-cooled type heat exchanger has been described as an example. However, the compressor cooling system 28 may include a liquid-cooled type (for example, a water-cooled type) heat exchanger in addition to the air-cooled type heat exchanger. Therefore, the compressor cooling system 28 may include a refrigerant gas cooler that cools the refrigerant gas line 18 by heat exchange between the refrigerant gas and a cooling medium (for example, cooling water) and an oil cooler that cools the oil circulation line 20 by heat exchange between the oil and the cooling medium. The compressor casing 24 may be provided with a cooling medium inlet and a cooling medium outlet. The cooling medium may be supplied to the compressor 12 from the outside through the cooling medium inlet, and may be discharged outward of the compressor 12 after passing through the refrigerant gas cooler and the oil cooler. In this way, the compression heat generated in the compressor body 16 may be removed outward of the compressor 12 together with the cooling medium.

In the above-described embodiment, a case where the cryocooler 10 is used as the cooling source of the measurement device has been described as an example. However, the cryocooler 10 may be used to cool other various objects to be cooled. For example, the cryocooler 10 may be used as the cooling source for a superconducting magnet device. For example, the superconducting magnet device is mounted on high magnetic field using devices as magnetic field sources of accelerators 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 present invention has been described by using specific terms and phrases, based on the embodiments. However, the embodiments show only one aspect of principles and applications of the present invention. The embodiments allow many modification examples or disposition changes within the scope not departing from the idea of the present invention defined in the appended claims.

It should be understood that the invention is not limited to the above-described embodiment, but may be modified into various forms on the basis of the spirit of the invention. Additionally, the modifications are included in the scope of the invention.