JP6871881B2 - Cryogenic refrigerator system and oscillator unit - Google Patents

Description

The present invention relates to a cryogenic refrigerator system and a vibrator unit.

One of the main applications of cryogenic refrigerators is the cooling of superconducting magnets. The strong static magnetic field created by superconducting magnets is used, for example, in magnetic resonance imaging (MRI). MR elastography (MRE), which is an application of MRI, has been attracting attention in recent years as a new and useful diagnostic imaging method. In the MRE, it is necessary to give a mechanical vibration to the subject when acquiring an image, and therefore, a vibrating device used for the MRE has been proposed.

International Publication No. 2012/026543

Exciters for MRE need to be adapted to high magnetic field environments, but such existing exciters tend to be large and complex designs. A restricted access area that can be affected by a high magnetic field is defined around the MRE imaging device. In order to avoid the influence of the magnetic field, the exciter is placed outside the restricted access area, for example, in a room separate from the imaging room in which the MRE imaging device is installed. In the vibration exciter, the sound generator generates an acoustic signal from an electric signal, and the acoustic signal is amplified and converted into a sound wave signal via a loudspeaker. In addition, the sound wave signal is converted into air vibration. Air vibration is transmitted to the vibration output section used with the MRE image pickup device by a transmission section of a non-magnetic material such as a long hose of several meters or more extending from the outside to the inside of the restricted access area. The vibration output unit, also called a vibration pad or the like, physically contacts the subject imaged by the MRE imaging device to give the subject mechanical vibration.

As described above, it is difficult to install the existing vibration exciter near the place where vibration is used, and the place where it can be installed is restricted. In addition, since the vibration exciter is large, it is necessary to take a large installation space.

If the transmission distance of vibration is long, the vibration can be damped. In addition, a delay may occur from the oscillation in the vibration exciter to the reception in the subject. Then, it becomes difficult to reliably apply the desired vibration to the subject at the desired timing.

Complex vibration devices have correspondingly high manufacturing costs.

These inconveniences are not limited to exciters for MRE and can occur in other situations where it is desirable to use vibrations near superconducting magnets or other high magnetic field sources.

One exemplary object of an aspect of the present invention is to provide a novel cryogenic refrigerator system and oscillator unit that addresses at least one of the above issues.

According to an aspect of the present invention, the cryogenic refrigerator system comprises a compressor having a discharge port and a suction port, a cold head having a high pressure port and a low pressure port, and the discharge port of the compressor as the cold head. A high-pressure line connecting to the high-pressure port, a low-pressure line connecting the suction port of the compressor to the low-pressure port of the cold head, and parallel to the cold head between the high-pressure line and the low-pressure line. A connected excitation unit, the refrigerant gas chamber accommodating the refrigerant gas, and the refrigerant gas chamber alternating between the high pressure line and the low pressure line so as to generate the pressure vibration of the refrigerant gas in the refrigerant gas chamber. A vibration unit including a valve unit connected to the above and a vibration transmission unit that mechanically or electrically transmits vibration corresponding to the pressure vibration of the refrigerant gas to the vibration utilization device.

According to an aspect of the present invention, the oscillating unit is a oscillating unit that can be installed in an ultra-low temperature refrigerating system, and the oscillating unit is a refrigerant gas sent from a compressor to a cold head. A refrigerant gas chamber for accommodating the refrigerant gas is connected in parallel with the cold head between the flowing high-pressure line and the low-pressure line through which the refrigerant gas recovered from the cold head to the compressor flows. And the valve portion that alternately connects the refrigerant gas chamber to the high pressure line and the low pressure line so as to generate the pressure vibration of the refrigerant gas in the refrigerant gas chamber, and the vibration corresponding to the pressure vibration of the refrigerant gas. It is provided with a vibration transmission unit that mechanically or electrically transmits to the vibration utilization device.

It should be noted that any combination of the above components or components and expressions of the present invention that are mutually replaced between methods, devices, systems, and the like are also effective as aspects of the present invention.

According to the present invention, it is possible to provide a novel cryogenic refrigerator system and a vibrator unit.

It is a figure which shows schematicly the cryogenic refrigerator system which concerns on a certain embodiment. It is the schematic which shows the appearance of the exciting part which concerns on a certain embodiment. It is the schematic which shows the inside of the exciting part shown in FIG. It is the schematic which shows another example of the vibration transmission part of the vibration part which concerns on a certain embodiment. It is the schematic which shows another example of the vibration transmission part of the vibration part which concerns on a certain embodiment.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent components, members, and processes are designated by the same reference numerals, and duplicate description will be omitted as appropriate. The scales and shapes of the illustrated parts are set for convenience of explanation and are not to be interpreted in a limited manner unless otherwise specified. Embodiments are exemplary and do not limit the scope of the invention in any way. Not all features and combinations thereof described in the embodiments are necessarily essential to the invention.

FIG. 1 is a diagram schematically showing a cryogenic refrigerator system 10 according to an embodiment. The cryogenic refrigerator system 10 includes a compressor 12 and a cold head 14 constituting a cryogenic refrigerator, and a vibration unit 16.

The compressor 12 is configured to recover the refrigerant gas of the cryogenic refrigerator from the cold head 14, pressurize the recovered refrigerant gas, and supply the refrigerant gas to the cold head 14 again. The cold head 14, also referred to as an expander, has a room temperature portion 18 and at least one low temperature portion 20. As shown in the figure, when the cold head 14 is of a two-stage type, the cold head 14 has a low temperature portion 20 in each of the first stage and the second stage. The cold head 14 may be of a single stage type. The low temperature section 20 is also referred to as a cooling stage.

The refrigeration cycle of the ultra-low temperature refrigerator is configured by circulating the refrigerant gas between the compressor 12 and the cold head 14 with an appropriate combination of pressure fluctuation and volume fluctuation of the refrigerant gas in the cold head 14. , The low temperature part 20 is cooled to a desired extremely low temperature. Thereby, for example, a superconducting electromagnet thermally coupled to the low temperature portion 20 or any other object to be cooled can be cooled to the target cooling temperature. The refrigerant gas is usually helium gas, but other suitable gases may be used. For understanding, the direction in which the refrigerant gas flows is indicated by an arrow in FIG.

Cryogenic refrigerators are, for example, two-stage Gifford-McMahon (GM) refrigerators, but pulse tube refrigerators, Stirling refrigerators, or other types of cryogenic refrigerators. May be good. The cold head 14 has a different configuration depending on the type of cryogenic refrigerator. The compressor 12 can use the same configuration regardless of the type of cryogenic refrigerator.

In general, the pressure of the refrigerant gas supplied from the compressor 12 to the cold head 14 and the pressure of the refrigerant gas recovered from the cold head 14 to the compressor 12 are both considerably higher than the atmospheric pressure, and are the first high pressure and the first high pressure, respectively. It can be called the second high pressure. For convenience of explanation, the first high pressure and the second high pressure are also simply referred to as high pressure and low pressure, respectively. Typically, the high pressure is in the range of, for example, about 2-3 MPa, and the low pressure is, for example, in the range of about 0.5 to 1.5 MPa.

The compressor 12 has a discharge port 12a and a suction port 12b. The discharge port 12a is an outlet of the refrigerant gas provided in the compressor 12 for sending the refrigerant gas pressurized to a high pressure by the compressor 12 from the compressor 12, and the suction port 12b compresses the low pressure refrigerant gas. It is an inlet of a refrigerant gas provided in the compressor 12 for receiving in the machine 12.

The cold head 14 has a high pressure port 14a and a low pressure port 14b. The high-pressure port 14a is an inlet for the refrigerant gas provided in the room temperature portion 18 of the cold head 14 in order to receive the high-pressure working gas inside the low-temperature portion 20 of the cold head 14. The low-pressure port 14b is provided in the room temperature portion 18 of the cold head 14 in order to discharge the low-pressure refrigerant gas decompressed by the expansion of the refrigerant gas inside the low-temperature portion 20 of the cold head 14 from the cold head 14. It is the exit of.

Further, the cryogenic refrigerator system 10 includes a piping system 22 that connects the compressor 12 and the cold head 14 so as to circulate the refrigerant gas. The piping system 22 includes a high-pressure line 24 that connects the discharge port 12a of the compressor 12 to the high-pressure port 14a of the cold head 14, and a low-pressure line 26 that connects the suction port 12b of the compressor 12 to the low-pressure port 14b of the cold head 14. To be equipped. Therefore, the high-pressure refrigerant gas is supplied from the compressor 12 to the cold head 14 through the high-pressure line 24, and the low-pressure refrigerant gas is recovered from the cold head 14 to the compressor 12 through the low-pressure line 26.

The exciting portion 16 is connected in parallel with the cold head 14 between the high pressure line 24 and the low pressure line 26. The vibration generating unit 16 includes a refrigerant gas chamber 28, a valve unit 30, and a vibration transmitting unit 32. The refrigerant gas chamber 28 accommodates the refrigerant gas, and the valve portion 30 is configured to alternately connect the refrigerant gas chamber 28 to the high pressure line 24 and the low pressure line 26, whereby the valve portion 30 causes the pressure vibration of the refrigerant gas. Is generated in the refrigerant gas chamber 28. The vibration transmission unit 32 is configured to mechanically or electrically transmit vibration corresponding to the pressure vibration of the refrigerant gas to the vibration utilization device 34.

The valve portion 30 includes a supply valve 30a for supplying the refrigerant gas from the high-pressure line 24 to the refrigerant gas chamber 28, and an exhaust valve 30b for discharging the refrigerant gas from the refrigerant gas chamber 28 to the low-pressure line 26. The valve unit 30 supplies and discharges the refrigerant gas to the refrigerant gas chamber 28 by opening and closing the supply valve 30a and the discharge valve 30b at appropriate timings (for example, by opening and closing alternately), and causes pressure vibration of the refrigerant gas. Can be generated. The valve portion 30 is configured to generate a pressure vibration having a desired frequency and amplitude in the refrigerant gas chamber 28.

As an example, the valve section 30 takes the form of a single rotary valve incorporating a supply valve 30a and a discharge valve 30b. Alternatively, where applicable, the valve section 30 may take the form of a plurality of individually controllable valves, and the supply valve 30a and the discharge valve 30b may each be individually controllable solenoid valves. ..

The vibration transmission unit 32 is connected to the vibration utilization device 34 by a vibration transmission pipe 33 or electrical wiring. The vibration corresponding to the pressure vibration of the refrigerant gas is mechanically or electrically input from the vibration transmission unit 32 to the vibration utilization device 34 through the vibration transmission pipe 33 or the electric wiring. The vibration utilization device 34 is configured to output the input mechanical vibration, amplify the input mechanical vibration and output it, or convert the input electrical vibration into mechanical vibration and output it. It may have been done.

The vibration unit 16 is manufactured by, for example, the manufacturer of the cryogenic refrigerator system 10 and provided to the user. However, the vibration utilization device 34 may not be considered to be a part of the vibration unit 16. For example, when the vibration unit 16 is used together with the MRE image pickup device, the vibration utilization device 34 is a vibration pad that physically contacts the subject imaged by the MRE image pickup device and gives mechanical vibration to the subject. There may be. The vibration pad may be provided to the user by the manufacturer of the MRE imaging device separately from the vibration unit 16. Alternatively, in other situations, the vibration utilization device 34 may form part of the vibration unit 16 and may be provided to the user, for example, by the manufacturer of the cryogenic refrigerator system 10.

An exemplary configuration of the vibrating unit 16 will be described in detail later.

The cryogenic refrigerator system 10 is configured to select and operate either the cold head 14 or the vibration unit 16. That is, the cryogenic refrigerator system 10 is configured to stop the vibration unit 16 while operating the cold head 14, and stop the cold head 14 while operating the vibration unit 16.

Therefore, the piping system 22 includes a high-pressure switching valve 36, a low-pressure switching valve 38, a high-pressure connecting pipe 40, and a low-pressure connecting pipe 42.

The high-pressure switching valve 36 is arranged on the high-pressure line 24, and is configured to switch and connect the discharge port 12a of the compressor 12 to either the cold head 14 or the exciting portion 16. The low-pressure switching valve 38 is arranged on the low-pressure line 26, and is configured to switch and connect the suction port 12b of the compressor 12 to either the cold head 14 or the exciting portion 16. The high pressure switching valve 36 and the low pressure switching valve 38 may each have a set of on-off valve, a three-way valve, or any other suitable valve configuration.

The high-pressure switching valve 36 and the low-pressure switching valve 38 connect either the cold head 14 or the exciting portion 16 to both the high-pressure line 24 and the low-pressure line 26, and connect the other from both the high-pressure line 24 and the low-pressure line 26. It is configured to work synchronously so that it is detached. The high pressure switching valve 36 and the low pressure switching valve 38 may be switched by automatic control or may be switched manually.

The high-pressure connection pipe 40 connects the high-pressure line 24 to the vibration unit 16, and the low-pressure connection pipe 42 connects the low-pressure line 26 to the vibration unit 16. More specifically, the high-pressure connecting pipe 40 connects the high-pressure switching valve 36 to the supply valve 30a of the valve portion 30, and the low-pressure connecting pipe 42 connects the low-pressure switching valve 38 to the discharge valve 30b of the valve portion 30. The high-pressure connection pipe 40 and the low-pressure connection pipe 42 may be, for example, a flexible pipe or a flexible hose, or may be a rigid pipe.

Therefore, when the high-pressure switching valve 36 and the low-pressure switching valve 38 are switched to the cold head 14, the refrigerant gas is supplied from the discharge port 12a of the compressor 12 to the high-pressure port 14a of the cold head 14 through the high-pressure line 24. Refrigerant gas is recovered from the low pressure port 14b of the cold head 14 to the suction port 12b of the compressor 12 through the low pressure line 26. In this way, the cryogenic refrigerator system 10 can perform the cooling operation of the cold head 14. At this time, the vibration unit 16 is separated from the compressor 12.

When the high-pressure switching valve 36 and the low-pressure switching valve 38 are switched to the exciting portion 16, the refrigerant is sent from the discharge port 12a of the compressor 12 to the supply valve 30a of the exciting portion 16 through the high-pressure line 24 and the high-pressure connecting pipe 40. Gas is supplied, and the refrigerant gas is recovered from the discharge valve 30b of the exciting portion 16 to the suction port 12b of the compressor 12 through the low-pressure connecting pipe 42 and the low-pressure line 26. The operation of the valve unit 30 generates pressure vibration of the refrigerant gas in the refrigerant gas chamber 28, and the vibration based on the pressure vibration is mechanically or electrically output to the vibration utilization device 34 by the vibration transmission unit 32. In this way, the cryogenic refrigerator system 10 can output a desired vibration from the vibration unit 16. At this time, the cold head 14 is separated from the compressor 12.

The cryogenic refrigerator system 10 may be configured to operate the cold head 14 and the vibration unit 16 at the same time. In this case, the piping system 22 does not have to include the high pressure switching valve 36 with the low pressure switching valve 38. The piping system 22 includes a high-voltage branching portion that branches the high-voltage line 24 to the high-voltage connecting pipe 40 instead of the high-voltage switching valve 36, and branches the low-voltage line 26 to the low-voltage connecting pipe 42 instead of the low-voltage switching valve 38. It may be provided with a low pressure branching portion to allow

Further, the piping system 22 may include a bypass unit 44. The bypass unit 44 is connected in parallel with the cold head 14 between the high voltage line 24 and the low voltage line 26. The bypass unit 44 connects the high pressure line 24 to the low pressure line 26 so as to bypass the cold head 14 and return the refrigerant gas from the high pressure line 24 to the low pressure line 26.

The bypass unit 44 has a bypass line 44a that connects the high pressure line 24 to the low pressure line 26, and a bypass valve 44b arranged on the bypass line 44a. The bypass line 44a is separated from the high pressure line 24 between the discharge port 12a of the compressor 12 and the high pressure switching valve 36, and joins the low pressure line 26 between the suction port 12b of the compressor 12 and the low pressure switching valve 38. There is. As an example, the bypass valve 44b may include a flow rate control valve that controls the flow rate of the refrigerant gas in the bypass line 44a. In this case, by changing the opening degree of the bypass valve 44b, the flow rate of the refrigerant gas in the bypass line 44a changes, and thereby the refrigerant gas pressures in the high pressure line 24 and the low pressure line 26 also change.

The bypass unit 44 may be used to reduce the refrigerant gas pressure that operates the vibrating unit 16. As described above, the operating pressure of the cold head 14 is quite high, but the operation of the exciting portion 16 does not necessarily require such a high pressure. By opening the bypass valve 44b, the refrigerant gas pressure of the high pressure line 24 is reduced. Therefore, the cryogenic refrigerator system 10 adjusts the bypass valve 44b of the bypass unit 44 to an appropriate opening degree when the cold head 14 is stopped to operate the vibration unit 16, thereby causing the vibration unit 16 to operate. It may be configured to adjust the pressure of the supplied refrigerant gas. By appropriately reducing the refrigerant gas pressure supplied to the vibration unit 16, the vibration unit 16 does not have to withstand excessive high pressure, so that the structure of the vibration unit 16 can be made simpler and lighter. it can.

Each component of the cryogenic refrigerator system 10 is supplied with power from the main power supply 45. The main power supply 45 may be, for example, a commercial power supply or a power supply device connected to the commercial power supply. The compressor 12, the cold head 14, and the vibration unit 16 are each connected to the main power supply 45 by power supply wiring. Therefore, it is not necessary to separately prepare a dedicated power supply for the vibration unit 16. Various known configurations can be adopted for the power supply system of the cryogenic refrigerator system 10.

FIG. 2 is a schematic view showing the appearance of the exciting portion 16 according to a certain embodiment. FIG. 3 is a schematic view showing the inside of the exciting portion 16 shown in FIG. The illustrated vibrating unit 16 can be applied to the cryogenic refrigerator system 10 shown in FIG.

The vibrating unit 16 is detachably connected to each of the high-voltage line 24 and the low-voltage line 26, and is configured as a portable unit.

The vibration unit 16 includes a single vibration unit housing 46 that houses a refrigerant gas chamber 28, a valve unit 30, and a vibration transmission unit 32. The vibration generating portion housing 46 is configured as a pressure vessel that can withstand the pressure of the refrigerant gas supplied to the refrigerant gas chamber 28. Further, the vibration unit 16 includes a motor unit 48 that drives the valve unit 30, and the motor unit 48 is also housed in the vibration unit housing 46. The motor unit 48 is, for example, a small AC synchronous motor. The vibrating portion 16 may include a magnetic shield 50 that covers the motor portion 48, and the magnetic shield 50 may be attached to the vibrating portion housing 46 so as to surround the motor portion 48.

The vibration unit housing 46 has a refrigerant gas supply port 52 and a refrigerant gas discharge port 54. The refrigerant gas supply port 52 is provided in the vibration unit housing 46 as a refrigerant gas inlet from the high-pressure connection pipe 40 to the valve portion 30, and the refrigerant gas discharge port 54 is a refrigerant gas outlet from the valve portion 30 to the low-pressure connection pipe 42. Is provided in the vibration portion housing 46. As an example, the refrigerant gas supply port 52 and the refrigerant gas discharge port 54 are removable joints such as a self-sealing coupling, and the high-pressure connection pipe 40 and the low-pressure connection pipe 42 are the refrigerant gas supply port 52 and the refrigerant gas, respectively. It can be easily attached to or removed from the discharge port 54.

The valve portion 30 includes a valve stator 56 and a valve rotor 58, and functions as a supply valve 30a and a discharge valve 30b by rotating the valve rotor 58 with respect to the valve stator 56.

The valve stator 56 is fixed to the exciting portion housing 46. The valve rotor 58 is connected to the motor unit 48 so as to rotate around its central axis by being driven by the motor unit 48. In FIG. 3, the rotation is indicated by an arrow A1. The bottom surface of the valve rotor 58 is in surface contact with the top surface of the valve stator 56. As the motor unit 48 is driven to rotate, the bottom surface of the valve rotor 58 rotates and slides with respect to the upper surface of the valve stator 56.

In FIG. 3, the flow direction of the refrigerant gas in the vibrating portion 16 is indicated by an arrow, and the refrigerant gas flow path formed inside the valve portion 30 is schematically indicated by a broken line. The valve portion 30 is configured to switch between a high pressure state and a low pressure state of the refrigerant gas chamber 28 by changing the rotation angle of the valve rotor 58 with respect to the valve stator 56. The high pressure state corresponds to the open state of the supply valve 30a, and the low pressure state corresponds to the open state of the discharge valve 30b.

The valve portion 30 is configured so that the refrigerant gas chamber 28 is not connected to the high pressure line 24 and the low pressure line 26 at the same time. That is, the refrigerant gas flow does not short-circuit from the high-pressure line 24 to the low-pressure line 26 through the vibrating portion 16.

In the high pressure state, the refrigerant gas is introduced into the refrigerant gas chamber 28 from the high pressure line 24 through the high pressure connecting pipe 40, the refrigerant gas supply port 52, and the internal flow path of the valve portion 30 (arrow A2), and the pressure in the refrigerant gas chamber 28 increases. .. In the low pressure state, the refrigerant gas is discharged from the refrigerant gas chamber 28 to the low pressure line 26 through the internal flow path of the valve portion 30, the refrigerant gas discharge port 54, and the low pressure connecting pipe 42 (arrow A3), and the pressure in the refrigerant gas chamber 28 is increased. Go down.

Therefore, the valve rotor 58 continuously rotates with respect to the valve stator 56 due to the rotation of the motor unit 48, so that the high-pressure state and the low-pressure state of the refrigerant gas chamber 28 are alternately and periodically switched. Therefore, pressure vibration of the refrigerant gas is generated in the refrigerant gas chamber 28.

In the illustrated example, the valve rotor 58 of the valve portion 30 is arranged in the high pressure chamber 60 in which the high pressure refrigerant gas communicates with the refrigerant gas supply port 52, but this is not essential. It is also possible to arrange the valve rotor 58 in a low pressure chamber in which the low pressure refrigerant gas communicates with the refrigerant gas discharge port 54 and is introduced.

Various known configurations can be adopted for the refrigerant gas flow path switching mechanism of the cryogenic refrigerator by the rotary valve type that can be used as the valve portion 30, and further detailed description thereof will be omitted in this document.

The vibration transmission unit 32 includes a vibration converter 62 and a vibration output port 64. The vibration converter 62 is connected to the refrigerant gas chamber 28 so that the pressure vibration of the refrigerant gas is transmitted, and is configured to convert the pressure vibration of the refrigerant gas into mechanical vibration corresponding to the pressure vibration. The vibration output port 64 is installed in the vibration converter 62 so as to output mechanical vibration from the vibration converter 62 so as to transmit the vibration to the vibration utilization device 34.

The vibration converter 62 accommodates a working fluid different from the refrigerant gas, and includes a working fluid chamber 66 connected to the refrigerant gas chamber 28 so that the pressure vibration of the refrigerant gas is transmitted to the working fluid. The working fluid is, for example, air. In that case, the working fluid is easy to handle. However, the working fluid may be another gas or liquid suitable for vibration transmission.

In addition, the vibration transducer 62 includes a piston 68 that separates the working fluid chamber 66 from the refrigerant gas chamber 28. The upper surface of the piston 68 faces the lower surface of the valve stator 56, and the refrigerant gas chamber 28 is defined by both sides of the piston 68 and the inner surface of the exciting portion housing 46. Therefore, the upper surface of the piston 68 receives the pressure of the refrigerant gas from the refrigerant gas chamber 28. Further, the working fluid chamber 66 is defined by the lower surface of the piston 68 and the inner surface of the exciting portion housing 46, and the lower surface of the piston 68 receives the pressure of the working fluid from the working fluid chamber 66.

The piston 68 can be moved by the pressure difference between the working fluid chamber 66 and the refrigerant gas chamber 28. The vibration portion housing 46 slidably supports the piston 68 so as to guide the movement of the piston 68. The average pressure of the working fluid housed in the working fluid chamber 66 is set to be substantially equal to, for example, the refrigerant gas pressure of the refrigerant gas chamber 28.

Therefore, in the high pressure state of the refrigerant gas chamber 28, the piston 68 moves in the direction away from the valve portion 30 (arrow A4), whereby the pressure in the working fluid chamber 66 also increases. In the low pressure state of the refrigerant gas chamber, the piston 68 moves in the direction approaching the valve portion 30 (arrow A5), whereby the pressure in the working fluid chamber 66 also decreases. In this way, the pressure vibration of the refrigerant gas in the refrigerant gas chamber 28 is transmitted to the working fluid in the working fluid chamber 66. In other words, the pressure vibration of the refrigerant gas is converted into the pressure vibration of the working fluid.

A regulating member 69 that regulates the movable range of the piston 68 may be provided on the inner surface of the exciting portion housing 46. Further, the piston 68 functions as a seal that prevents or minimizes the leakage of the refrigerant gas from the refrigerant gas chamber 28 to the working fluid chamber 66 and the leakage of the working fluid from the working fluid chamber 66 to the refrigerant gas chamber 28. A sealing member that seals the leakage of such refrigerant gas or working fluid may be mounted between the piston 68 and the oscillating portion housing 46.

The working fluid chamber 66 is connected to the refrigerant gas chamber 28 via a piston 68 so that the pressure vibration of the refrigerant gas is transmitted to the working fluid, but the working fluid chamber 66 is not limited to this. Instead of a movable partition wall such as a piston 68 that transmits vibration by its own displacement, for example, an elastically deformable flexible membrane that transmits vibration by deformation may be provided. The working fluid chamber 66 may be connected to the refrigerant gas chamber 28 via such a flexible film member so that the pressure vibration of the refrigerant gas is transmitted to the working fluid.

The vibration output port 64 is provided in the vibration transmitting portion housing 46 as an outlet for extracting vibration from the vibration transmitting portion 32, that is, the working fluid chamber 66 to the outside. As an example, as shown, the vibration output port 64 is provided at the bottom of the working fluid chamber 66, but may be arranged at another place such as a side wall of the working fluid chamber 66. The vibration output port 64 is configured so that the vibration transmission tube 33 can be attached and detached. The vibration transmission tube 33 may be, for example, a flexible hose. The pressure vibration of the working fluid transmitted to the working fluid chamber 66 is further transmitted to the vibration utilization device 34 via the working fluid inside the vibration transmission pipe 33. If the working fluid inside the vibration transmission pipe 33 is the same type (for example, air) as the working fluid in the working fluid chamber 66, it is easy to handle and convenient, but different working fluids may be used.

The vibration output from the vibration generating unit 16 to the vibration utilization device 34 can be adjusted. For example, by changing the rotation speed of the motor unit 48, the frequency of vibration can be directly changed, and the amplitude of vibration can also be changed to some extent. By changing the flow rate of the refrigerant gas passing through the bypass unit 44, the pressure difference between the high-pressure line 24 and the low-pressure line 26 is changed, whereby the amplitude of vibration can be changed. Further, the amplitude and frequency of vibration can be adjusted by changing the design of the valve portion 30, such as the arrangement and shape of the internal flow path of the valve portion 30.

In this way, according to the cryogenic refrigerator system 10 according to the embodiment, the vibration unit 16 excites the desired vibration and provides the desired vibration to the vibration utilization device 34, for example, the vibration pad of the MRE image pickup device. can do.

Compared with the conventionally known vibration exciter for MRE, the vibration unit 16 has a small size and a simple structure, and is therefore advantageous in various viewpoints such as reduction of installation space, energy saving, and manufacturing cost. One of the main reasons for this is that the vibration unit 16 is added to the existing cryogenic refrigerator having the compressor 12 and the cold head 14. Since the compressor 12 can be used as the refrigerant gas source in the vibration generating unit 16, unlike the conventional vibration exciter for MRE, a dedicated oscillation source having a complicated configuration is unnecessary. Also, since an existing power source (eg, main power source 45) can be used, no additional power source is required, and there is little or no increase in power consumption.

Cryogenic refrigerators used to cool superconducting magnets are originally designed to accommodate high magnetic field environments. As described above, the valve unit 30, which is one of the main components of the vibration unit 16, can adopt the same or similar design as the configuration used in the existing cryogenic refrigerator. Therefore, it is extremely easy for the manufacturer of the cryogenic refrigerator system 10 to design the valve portion 30 so as to be compatible with a high magnetic field environment. There are no particular design difficulties with the other components of the vibrating portion 16 in adapting to a high magnetic field environment. Therefore, the vibrating unit 16 can be installed in a high magnetic field environment like the compressor 12 and the cold head 14.

Therefore, unlike the conventionally known vibration exciter for MRE, the vibration unit 16 can be arranged in the vicinity of the MRE image pickup device in the restricted access area. The vibration transmission distance from the vibration generating unit 16 to the vibration utilization device 34 is considerably shortened, and vibration can be efficiently transmitted. The vibration transmission loss is small, and the delay from the oscillation at the oscillation unit 16 to the vibration reception at the subject can be reduced to the extent that there is no significant effect.

Further, the vibrating unit 16 is detachably connected to each of the high pressure line 24 and the low pressure line 26, and is configured as a portable unit. In this way, the vibrating unit 16 can be added to the cryogenic refrigerator later and installed, which is convenient. The vibrating unit 16 can be carried and attached to an existing cryogenic refrigerator as an accessory or accessory of the cryogenic refrigerator.

Further, the vibration unit 16 has a vibration converter 62 and a vibration output port 64. The vibration converter 62 can convert the pressure vibration of the refrigerant gas into the vibration of another medium, and the reduction of the refrigerant gas circulating in the cryogenic refrigerator system 10 such as the leakage of the refrigerant gas is suppressed. Further, vibration can be easily provided to the vibration utilization device 34 by a relatively simple operation of connecting the vibration output port 64 to the vibration utilization device 34.

By using the working fluid chamber 66 as the vibration converter 62, a more manageable working fluid other than the refrigerant gas can be used as a medium for transmitting vibration to the vibration utilizing device 34.

In the above-described embodiment, the cold head 14 is stopped while the exciting unit 16 is in operation. Therefore, the cold head 14 does not affect the operation of the vibrating unit 16 and the vibration utilizing device 34. Further, the vibrating unit 16 is stopped while the cold head 14 is in operation. Therefore, the operation of the vibrating unit 16 does not deteriorate the cooling performance of the cold head 14.

FIG. 4 is a schematic view showing another example of the vibration transmission unit 32 of the vibration unit 16 according to a certain embodiment. Similar to the above-described embodiment, the pressure vibration of the refrigerant gas in the refrigerant gas chamber 28 is transmitted to the vibration transmission unit 32. The vibration transducer 62 of the vibration transmission unit 32 may include a pressure transducer 70 arranged inside the working fluid chamber 66. The pressure converter 70 is configured to convert the pressure vibration of the working fluid in the working fluid chamber 66 into electrical vibration corresponding to the pressure vibration. The pressure transducer 70 is also commonly referred to as a pressure transmitter or pressure transducer.

The vibration output port 64 is installed in the vibration converter 62 so as to output electrical vibration from the vibration converter 62 so as to transmit the vibration to the vibration utilization device 34. The pressure converter 70 is electrically connected to the vibration output port 64, and the vibration output port 64 is provided as an output terminal for outputting an electric signal representing the electric vibration generated by the pressure converter 70 according to the pressure vibration of the working fluid. Has been done. Therefore, the vibration output port 64 is connected to the vibration utilization device 34 by the signal line 72, and the electric signal representing the electric vibration can be output from the pressure converter 70 to the vibration utilization device 34 through the signal line 72.

Even in this way, the vibration transmission unit 32 can take out the vibration corresponding to the pressure vibration of the refrigerant gas to the outside. The vibration unit 16 can provide a desired vibration to the vibration utilization device 34.

FIG. 5 is a schematic view showing another example of the vibration transmission unit 32 of the vibration unit 16 according to a certain embodiment. Similar to the above embodiment, the vibration unit 16 includes a refrigerant gas chamber 28, a valve unit 30, and a vibration transmission unit 32, which are housed in the vibration unit housing 46. Further, the vibrating unit 16 has a refrigerant gas supply port 52 to which the high-pressure connecting pipe 40 is connected, and a refrigerant gas discharge port 54 to which the low-pressure connecting pipe 42 is connected.

The vibration transmission unit 32 is arranged inside the refrigerant gas chamber 28 so that the pressure vibration of the refrigerant gas is transmitted, and is a vibration converter 62 that converts the pressure vibration of the refrigerant gas into an electric vibration corresponding to the pressure vibration. A vibration output port 64 installed in the vibration converter 62 may be provided so as to output electrical vibration from the vibration converter 62 so as to transmit the vibration to the vibration utilization device 34. The vibration converter 62 may be a pressure converter 70 installed in the refrigerant gas chamber 28 and converting the pressure vibration of the refrigerant gas into electrical vibration. The pressure converter 70 may be electrically connected to the vibration output port 64, and the vibration output port 64 may be connected to the vibration utilization device 34 by the signal line 72.

Even in this way, the vibration transmission unit 32 can take out the vibration corresponding to the pressure vibration of the refrigerant gas to the outside. The vibration unit 16 can provide a desired vibration to the vibration utilization device 34. The working fluid chamber 66 is not required, and the configuration is simple.

The present invention has been described above based on examples. It will be understood by those skilled in the art that the present invention is not limited to the above embodiment, various design changes are possible, various modifications are possible, and such modifications are also within the scope of the present invention. By the way.

The various features described in relation to one embodiment are also applicable to other embodiments. The new embodiments resulting from the combination have the effects of each of the combined embodiments.

10 Very low temperature refrigerator system, 12 Compressor, 12a Discharge port, 12b Suction port, 14 Cold head, 14a High pressure port, 14b Low pressure port, 16 Vibration unit, 24 High pressure line, 26 Low pressure line, 28 Refrigerant gas chamber, 30 Valve part, 32 vibration transmission part, 34 vibration utilization equipment, 62 vibration converter, 64 vibration output port, 66 working fluid chamber, 70 pressure converter.

Claims (6)

A compressor with a discharge port and a suction port,
A cold head with a high pressure port and a low pressure port,
A high-pressure line connecting the discharge port of the compressor to the high-pressure port of the cold head,
A low pressure line connecting the suction port of the compressor to the low pressure port of the cold head,
A vibration unit connected in parallel with the cold head between the high-voltage line and the low-voltage line.
Refrigerant gas chamber for accommodating refrigerant gas and
A valve portion that alternately connects the refrigerant gas chamber to the high pressure line and the low pressure line so as to generate pressure vibration of the refrigerant gas in the refrigerant gas chamber.
An ultra-low temperature refrigerator system including a vibration transmitting unit that mechanically or electrically transmits vibration corresponding to the pressure vibration of the refrigerant gas to a vibration utilizing device, and a vibration generating unit including the vibration transmitting unit. The ultra-low temperature refrigerator system according to claim 1, wherein the vibrating unit is detachably connected to each of the high-pressure line and the low-pressure line, and is configured as a portable unit. The vibration transmission unit
It is connected to the refrigerant gas chamber or arranged inside the refrigerant gas chamber so that the pressure vibration of the refrigerant gas is transmitted, and the pressure vibration of the refrigerant gas is mechanically or electrically vibrated according to the pressure vibration. With a vibration converter that converts to
1 or claim 1, further comprising a vibration output port installed in the vibration converter to output the mechanical vibration or the electrical vibration from the vibration converter so as to transmit the vibration to the vibration-utilizing device. 2. The ultra-low temperature refrigerating machine system according to 2. The vibration converter is characterized by accommodating a working fluid different from the refrigerant gas and including a working fluid chamber connected to the refrigerant gas chamber so that pressure vibration of the refrigerant gas is transmitted to the working fluid. The ultra-low temperature refrigerator system according to claim 3. The ultra-low temperature refrigerator system according to claim 3, wherein the vibration converter is installed in the refrigerant gas chamber and includes a pressure converter that converts the pressure vibration of the refrigerant gas into the electrical vibration. A oscillating unit that can be installed in a cryogenic refrigerator system, the oscillating unit is collected by a high-pressure line through which refrigerant gas sent from a compressor to a cold head flows and from the cold head to the compressor. The compressor unit is connected in parallel with the cold head to the low-pressure line through which the refrigerant gas flows.
A refrigerant gas chamber accommodating the refrigerant gas and
A valve portion that alternately connects the refrigerant gas chamber to the high pressure line and the low pressure line so as to generate pressure vibration of the refrigerant gas in the refrigerant gas chamber.
A vibrator unit including a vibration transmission unit that mechanically or electrically transmits vibration corresponding to the pressure vibration of the refrigerant gas to a vibration utilization device.

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