阅读说明：本技术 超低温制冷机系统及起振机单元 (Cryogenic refrigerator system and vibrator unit ) 是由 渡边真 于 2019-03-11 设计创作，主要内容包括：超低温制冷机系统(10)具备：压缩机(12)；冷头(14)；高压管路(24),其将压缩机(12)的吐出端口(12a)连接到冷头(14)的高压端口(14a)；低压管路(26),其将压缩机(12)的吸入端口(12b)连接到冷头(14)的低压端口(14b)；及起振部(16),其连接在高压管路(24)与低压管路(26)之间且与冷头(14)并联连接,所述起振部(16)具备：制冷剂气体室(28),其容纳制冷剂气体；阀部(30),其使制冷剂气体室(28)交替连接于高压管路(24)和低压管路(26),以便在制冷剂气体室(28)产生制冷剂气体的压力振动；及振动传递部(32),其将与制冷剂气体的压力振动相对应的振动以机械方式或电方式传递至振动利用设备(34)。(A cryogenic refrigerator system (10) is provided with: a compressor (12); a cold head (14); 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); a low-pressure line (26) connecting a suction port (12b) of the compressor (12) to a low-pressure port (14b) of the cold head (14); and an oscillation starting unit (16) connected between the high-pressure line (24) and the low-pressure line (26) and connected in parallel to the cold head (14), the oscillation starting unit (16) comprising: a refrigerant gas chamber (28) that contains a refrigerant gas; a valve portion (30) that alternately connects the refrigerant gas chamber (28) to the high-pressure line (24) and the low-pressure line (26) so as to generate pressure vibration of the refrigerant gas in the refrigerant gas chamber (28); and a vibration transmission unit (32) that transmits vibration corresponding to the pressure vibration of the refrigerant gas to the vibration utilization device (34) either mechanically or electrically.)

1. A cryogenic refrigerator system is characterized by comprising:

a compressor having a discharge port and a suction port;

a cold head having 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; and

A vibration starting portion connected between the high pressure line and the low pressure line and connected in parallel with the cold head,

the oscillation starting unit includes:

a refrigerant gas chamber that accommodates a refrigerant gas;

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; and

a vibration transmission portion that mechanically or electrically transmits vibration corresponding to the pressure vibration of the refrigerant gas to a vibration utilization device.

2. The cryogenic refrigerator system of claim 1,

the vibration generating unit is configured as a unit that is detachably connected to the high-pressure line and the low-pressure line and that can be transported.

3. The cryogenic refrigerator system according to claim 1 or 2,

the vibration transmission unit includes:

a vibration converter which is connected to the refrigerant gas chamber or is disposed in the refrigerant gas chamber so as to transmit pressure vibration of the refrigerant gas, and converts the pressure vibration of the refrigerant gas into mechanical vibration or electrical vibration corresponding to the pressure vibration; and

A vibration output port provided on the vibration transducer so that the mechanical vibration or the electrical vibration is output from the vibration transducer and transmitted to the vibration utilizing apparatus.

4. The cryogenic refrigerator system of claim 3,

the vibration converter includes a working fluid chamber that contains a working fluid different from the refrigerant gas, and the working fluid chamber is connected to the refrigerant gas chamber so that pressure vibration of the refrigerant gas is transmitted to the working fluid.

5. The cryogenic refrigerator system of claim 3,

the vibration converter includes a pressure converter that is disposed in the refrigerant gas chamber and converts pressure vibration of the refrigerant gas into the electric vibration.

6. A vibrator unit that can be installed in a cryogenic refrigerator system, the vibrator unit comprising:

a refrigerant gas chamber;

a valve portion that alternately connects the refrigerant gas chamber to a refrigerant gas high-pressure line and a refrigerant gas low-pressure line of the cryogenic refrigerator system to generate pressure vibration of the refrigerant gas in the refrigerant gas chamber; and

A vibration transmission portion that mechanically or electrically transmits vibration corresponding to the pressure vibration of the refrigerant gas to a vibration utilization device.

Technical Field

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

Background

One of the main uses of cryogenic refrigerators is the cooling of superconducting magnets. The strong static magnetic field generated by the superconducting magnet is used for Magnetic Resonance Imaging (MRI), for example. In recent years, MR elastography (MRE), one of applications of MRI, has attracted attention as a new and useful diagnostic imaging method. In the MRE, since it is necessary to apply mechanical vibration to the subject when acquiring an image, an excitation device for the MRE has been proposed.

Prior art documents

Patent document

Patent document 1 International publication No. 2012/026543

Disclosure of Invention

Technical problem to be solved by the invention

While the excitation device for MRE is required to be suitable for a high magnetic field environment, such a conventional excitation device is generally large and complicated in design. A confined inner region that is likely to be affected by high magnetic fields is defined around the MRE imaging apparatus. To avoid being affected by the magnetic field, the excitation device is placed outside the confined-in area (e.g., in another room than the studio in which the MRE imaging device is located). In the excitation device, the sound generation device generates a sound signal from an electric signal, and the sound signal is amplified and converted into a sound wave signal by a speaker. Then, the acoustic wave signal is converted into air vibration. The air vibration is transmitted to a vibration output portion used with the MRE imaging apparatus through a transmission portion (for example, a long hose or the like) of a nonmagnetic material of several meters or more extending from outside to inside the restricted-in inner region. The vibration output portion is also referred to as a vibration pad or the like, which is in physical contact with the subject imaged by the MRE imaging apparatus and applies mechanical vibration to the subject.

In this way, it is difficult to install the conventional exciting device near the vibration utilization site, and the installation position is limited. Further, since the exciting device is large, an installation space needs to be increased.

If the transmission distance of the vibration becomes long, the vibration is attenuated. Further, there is a possibility that a delay may occur from the oscillation in the excitation device until the subject receives the oscillation. In this way, it is difficult to reliably apply desired vibration to the subject at a desired timing.

The manufacturing cost of the complicated excitation device also increases accordingly.

These disadvantages are not only present in excitation devices for MREs, but may also be present in other cases where it is desirable to use vibrations in the vicinity of superconducting magnets or other high magnetic field sources.

An exemplary object of one embodiment of the present invention is to provide a novel cryogenic refrigerator system and a vibrator unit that can solve at least one of the above problems.

Means for solving the technical problem

According to an embodiment of the present invention, there is provided a cryogenic refrigerator system including: a compressor having a discharge port and a suction port; a cold head having 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; and a vibration starting unit connected between the high-pressure line and the low-pressure line and connected in parallel to the cold head, the vibration starting unit including: a refrigerant gas chamber that accommodates a refrigerant gas; 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; and a vibration transmission unit that transmits vibration corresponding to the pressure vibration of the refrigerant gas to a vibration utilization device mechanically or electrically.

According to an embodiment of the present invention, there is provided a vibrator unit that can be provided in a cryogenic refrigerator system, the vibrator unit including: a refrigerant gas chamber; a valve portion that alternately connects the refrigerant gas chamber to a refrigerant gas high-pressure line and a refrigerant gas low-pressure line of the cryogenic refrigerator system to generate pressure vibration of the refrigerant gas in the refrigerant gas chamber; and a vibration transmission unit that transmits vibration corresponding to the pressure vibration of the refrigerant gas to a vibration utilization device mechanically or electrically.

Any combination of the above-described constituent elements or substitution of the constituent elements and expressions of the present invention with each other in a method, an apparatus, a system, or the like is also effective as an embodiment of the present invention.

Effects of the invention

According to the present invention, a novel cryogenic refrigerator system and a vibrator unit can be provided.

Drawings

Fig. 1 is a diagram schematically showing a cryogenic refrigerator system according to an embodiment.

Fig. 2 is a schematic diagram showing an appearance of a vibration starting unit according to an embodiment.

Fig. 3 is a schematic view showing the inside of the vibration generating section shown in fig. 2.

Fig. 4 is a schematic view showing another example of the vibration transmission section of the excitation section according to the embodiment.

Fig. 5 is a schematic view showing still another example of the vibration transmission unit of the excitation unit according to the embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description and the drawings, the same or equivalent constituent elements, components, and processes are denoted by the same reference numerals, and overlapping description is appropriately omitted. For convenience of explanation, the scale and shape of each part are appropriately set in each drawing, and are not to be construed as limiting unless otherwise specified. The embodiments are merely examples, which do not limit the scope of the present invention in any way. All the features or combinations thereof described in the embodiments are not necessarily essential contents of the invention.

Fig. 1 is a diagram schematically showing a cryogenic refrigerator system 10 according to an embodiment. The cryogenic refrigerator system 10 includes an oscillation starting unit 16, and a compressor 12 and a cold head 14 that constitute the cryogenic refrigerator.

The compressor 12 is configured to recover refrigerant gas of the cryogenic refrigerator from the cold head 14, to increase the pressure of the recovered refrigerant gas, and to 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 fig. 1, in the case where the cold head 14 is of a two-stage type, the cold head 14 has low-temperature portions 20 in the 1 st stage and the 2 nd stage, respectively. The cold head 14 may also be of a single stage type. The low temperature part 20 is also referred to as a cooling stage.

The circulation of the refrigerant gas between the compressor 12 and the cold head 14 is accompanied by a combination of appropriate pressure fluctuation and volume fluctuation of the refrigerant gas in the cold head 14, thereby constituting a refrigeration cycle of the cryogenic refrigerator to cool the low-temperature portion 20 to a desired cryogenic temperature. This enables cooling of, for example, a superconducting electromagnet or any other object to be cooled thermally connected to low-temperature portion 20 to a target cooling temperature. Helium is typically used as the refrigerant gas, but other suitable gases may be used. For ease of understanding, in fig. 1, the flow direction of the refrigerant gas is indicated by an arrow.

For example, the cryogenic refrigerator is a two-stage Gifford-McMahon (GM) refrigerator, but may be a pulse tube refrigerator, a stirling refrigerator, or another type of cryogenic refrigerator. The cold head 14 has a different structure according to the type of the cryogenic refrigerator. As for the compressor 12, the same structure of the compressor can be used regardless of the type of the cryogenic refrigerator.

In addition, generally, 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 much higher than the atmospheric pressure, and may be referred to as the 1 st high pressure and the 2 nd high pressure, respectively. For convenience of description, the 1 st high voltage and the 2 nd high voltage are simply referred to as a high voltage and a low voltage, respectively. Typically, the high pressure is, for example, in the range of about 2 to 3MPa, 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 12 b. The discharge port 12a is an outlet of the refrigerant gas provided in the compressor 12 for outputting the refrigerant gas that has been pressurized by the compressor 12 to a high pressure from the compressor 12, and the suction port 12b is an inlet of the refrigerant gas provided in the compressor 12 for recovering the low pressure refrigerant gas into the compressor 12.

The cold head 14 has a high pressure port 14a and a low pressure port 14 b. The high-pressure port 14a is an inlet for refrigerant gas provided in the room-temperature portion 18 of the cold head 14 so that high-pressure working gas enters the interior of the low-temperature portion 20 of the cold head 14. The low-pressure port 14b is an outlet for the refrigerant gas provided in the room temperature portion 18 of the cold head 14 in order to discharge, from the cold head 14, the low-pressure refrigerant gas expanded and decompressed inside the low-temperature portion 20 of the cold head 14.

The cryogenic refrigerator system 10 is provided with a piping system 22 for connecting the compressor 12 and the cold head 14 to each other so as to circulate the refrigerant gas therebetween. The piping system 22 includes a high-pressure pipe line 24 connecting the discharge port 12a of the compressor 12 to the high-pressure port 14a of the cold head 14, and a low-pressure pipe line 26 connecting the suction port 12b of the compressor 12 to the low-pressure port 14b of the cold head 14. Thus, high pressure refrigerant gas is supplied from the compressor 12 to the cold head 14 through the high pressure line 24, and low pressure refrigerant gas is recovered from the cold head 14 to the compressor 12 through the low pressure line 26.

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

The valve portion 30 has a supply valve 30a for supplying the refrigerant gas from the high-pressure line 24 to the refrigerant gas chamber 28, and a discharge valve 30b for discharging the refrigerant gas from the refrigerant gas chamber 28 to the low-pressure line 26. The valve portion 30 can generate pressure oscillation of the refrigerant gas by opening and closing (e.g., alternately opening and closing) the supply valve 30a and the discharge valve 30b at appropriate timings to supply the refrigerant gas to the refrigerant gas chamber 28 or discharge the refrigerant gas from the refrigerant gas chamber 28. The valve portion 30 is configured to generate pressure vibration having a desired frequency and amplitude in the refrigerant gas chamber 28.

For example, the valve unit 30 is formed by a single rotary valve in which the supply valve 30a and the discharge valve 30b are incorporated. Alternatively, when applicable, the valve portion 30 may be in the form of a plurality of individually controllable valves, and the supply valve 30a and the discharge valve 30b may be solenoid valves that are individually controllable.

The vibration transmission portion 32 is connected to the vibration utilizing device 34 through a vibration transmission pipe 33 or an electric wire. Vibration corresponding to the pressure vibration of the refrigerant gas is input from the vibration transmitting portion 32 to the vibration utilizing device 34 via the vibration transmitting pipe 33 or the electric wire, respectively, mechanically or electrically. The vibration utilization device 34 may be configured to output the input mechanical vibration, amplify the input mechanical vibration, and output the amplified mechanical vibration, or convert the input electrical vibration into mechanical vibration and output the mechanical vibration.

The oscillating unit 16 is manufactured by, for example, a manufacturer of the cryogenic refrigerator system 10 and provided to a user. However, the vibration utilizing device 34 may not be a part of the vibrating section 16. For example, in the case where the oscillation starting portion 16 is used together with an MRE imaging apparatus, the oscillation utilization device 34 may be an oscillation pad that is in physical contact with a subject imaged by the MRE imaging apparatus and applies mechanical oscillation to the subject. The vibration pad may be provided separately from the vibrating portion 16 by the manufacturer of the MRE imaging apparatus to the user. Alternatively, in other cases, the vibration utilization device 34 may constitute a part of the excitation unit 16 and be provided to the user by, for example, the manufacturer of the cryogenic refrigerator system 10.

An exemplary structure of the oscillating portion 16 will be described in detail later.

The cryogenic refrigerator system 10 is configured to selectively operate one of the cold head 14 and the oscillating portion 16. That is, the cryogenic refrigerator system 10 is configured to stop the operation of the oscillating portion 16 while the cold head 14 is operated, and to stop the operation of the cold head 14 while the oscillating portion 16 is operated.

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

The high-pressure switching valve 36 is disposed in the high-pressure line 24, and is configured to switch between connecting the discharge port 12a of the compressor 12 to the cold head 14 and connecting the discharge port 12a of the compressor 12 to the vibration generating portion 16. The low-pressure switching valve 38 is disposed on the low-pressure line 26, and is configured to switch between connecting the suction port 12b of the compressor 12 to the cold head 14 and connecting the suction port 12b of the compressor 12 to the vibration generating portion 16. The high-pressure switching valve 36 and the low-pressure switching valve 38 may each have a set of on-off valves, three-way valves, or other suitable valve structures.

The high-pressure switching valve 36 and the low-pressure switching valve 38 are configured to operate synchronously such that one of the cold head 14 and the vibration generating unit 16 is connected to both the high-pressure line 24 and the low-pressure line 26 and the other is disconnected from both the high-pressure line 24 and the low-pressure line 26. The high-pressure switching valve 36 and the low-pressure switching valve 38 may be switched by automatic control or may be manually switched.

A high-pressure connection pipe 40 connects the high-pressure line 24 to the oscillation portion 16, and a low-pressure connection pipe 42 connects the low-pressure line 26 to the oscillation portion 16. More specifically, the high pressure connection pipe 40 connects the high pressure switching valve 36 to the supply valve 30a of the valve portion 30, and the low pressure connection 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 a flexible pipe or a flexible hose, or a rigid pipe, for example.

Therefore, when the high-pressure switching valve 36 and the low-pressure switching valve 38 are switched to be connected 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 via the high-pressure line 24, and the refrigerant gas is recovered from the low-pressure port 14b of the cold head 14 to the suction port 12b of the compressor 12 via the low-pressure line 26. Thereby, the cryogenic refrigerator system 10 can perform the cooling operation of the cold head 14. At this time, the vibration starting portion 16 is disconnected from the compressor 12.

When the high-pressure switching valve 36 and the low-pressure switching valve 38 are switched to be connected to the oscillation starting portion 16, the refrigerant gas is supplied from the discharge port 12a of the compressor 12 to the supply valve 30a of the oscillation starting portion 16 via the high-pressure line 24 and the high-pressure connection line 40, and the refrigerant gas is recovered from the discharge valve 30b of the oscillation starting portion 16 to the suction port 12b of the compressor 12 via the low-pressure connection line 42 and the low-pressure line 26. By the operation of the valve portion 30, pressure vibration of the refrigerant gas is generated in the refrigerant gas chamber 28, and vibration based on the pressure vibration is mechanically or electrically output to the vibration utilization device 34 through the vibration transmission portion 32. As a result, the cryogenic refrigerator system 10 can output a desired vibration from the vibration generator 16. At this point, cold head 14 is disconnected from compressor 12.

In addition, the cryogenic refrigerator system 10 may be configured such that the cold head 14 and the oscillating portion 16 are operated simultaneously. In this case, the piping system 22 may not include the high pressure switching valve 36 and the low pressure switching valve 38. The piping system 22 may include a high-pressure branch portion that branches the high-pressure line 24 into the high-pressure connection pipe 40 instead of the high-pressure switching valve 36, and may include a low-pressure branch portion that branches the low-pressure line 26 into the low-pressure connection pipe 42 instead of the low-pressure switching valve 38.

The piping system 22 may further include a bypass unit 44. The bypass unit 44 is connected between the high pressure line 24 and the low pressure line 26 and is connected in parallel with the cold head 14. A bypass unit 44 connects the high pressure line 24 to the low pressure line 26 to allow refrigerant gas to bypass the cold head 14 to flow from the high pressure line 24 back to the low pressure line 26.

The bypass unit 44 has a bypass line 44a connecting the high-pressure line 24 to the low-pressure line 26, and a bypass valve 44b disposed on the bypass line 44 a. The bypass line 44a branches from the high-pressure line 24 between the discharge port 12a of the compressor 12 and the high-pressure switching valve 36, and merges into the low-pressure line 26 between the suction port 12b of the compressor 12 and the low-pressure switching valve 38. For example, the bypass valve 44b may include a flow rate control valve for controlling the flow rate of the refrigerant gas in the bypass line 44 a. At this time, when the opening degree of the bypass valve 44b is changed, the refrigerant gas flow rate in the bypass line 44a is changed, and the refrigerant gas pressures in the high-pressure line 24 and the low-pressure line 26 are also changed.

The bypass unit 44 may also be used to reduce the refrigerant gas pressure for operating the oscillation generating portion 16. As described above, the operating pressure of the cold head 14 is considerably high, but the high pressure is not necessarily required for the operation of the oscillating portion 16. When the bypass valve 44b is opened, the refrigerant gas pressure in the high-pressure line 24 decreases. Therefore, the cryogenic refrigerator system 10 may be configured to adjust the refrigerant gas pressure supplied to the oscillation start portion 16 by adjusting the bypass valve 44b of the bypass unit 44 to an appropriate opening degree when the oscillation start portion 16 is operated by stopping the operation of the cold head 14. By appropriately reducing the pressure of the refrigerant gas supplied to the oscillation start portion 16, the oscillation start portion 16 does not need to receive an excessively high pressure, and therefore the structure of the oscillation start portion 16 can be made simpler and the weight can be reduced.

The components of the cryogenic refrigerator system 10 are 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 generating unit 16 are connected to a main power supply 45 through power supply wires. Therefore, the oscillation generator 16 does not need to separately prepare a dedicated power supply. In addition, the power supply system of the cryogenic refrigerator system 10 can take various known configurations.

Fig. 2 is a schematic diagram showing an external appearance of the oscillating portion 16 according to the embodiment. Fig. 3 is a schematic view showing the inside of the oscillation generating section 16 shown in fig. 2. The illustrated oscillation starting unit 16 can be applied to the cryogenic refrigerator system 10 shown in fig. 1.

The vibration generating portion 16 is configured as a transportable unit that is detachably connected to both the high-pressure line 24 and the low-pressure line 26.

The oscillation generating portion 16 includes a single oscillation generating portion case 46 that accommodates the refrigerant gas chamber 28, the valve portion 30, and the oscillation transmitting portion 32. The oscillation starting portion case 46 is configured as a pressure vessel capable of receiving the pressure of the refrigerant gas supplied to the refrigerant gas chamber 28. The oscillation generating unit 16 includes a motor unit 48 for driving the valve unit 30, and the motor unit 48 is also accommodated in the oscillation generating unit case 46. As an example, the motor unit 48 is a small AC synchronous motor. The excitation portion 16 may further include a magnetic shield 50 covering the motor portion 48, and the magnetic shield 50 may be attached to the excitation portion case 46 so as to surround the motor portion 48.

The oscillation generating portion 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 oscillation start housing 46 as a refrigerant gas inlet for supplying the refrigerant gas from the high-pressure connection pipe 40 to the valve portion 30, and the refrigerant gas discharge port 54 is provided in the oscillation start housing 46 as a refrigerant gas outlet for discharging the refrigerant gas from the valve portion 30 to the low-pressure connection pipe 42. For example, the refrigerant gas supply port 52 and the refrigerant gas discharge port 54 are detachable connectors (for example, self-sealing pipe joints), and the high-pressure connection pipe 40 and the low-pressure connection pipe 42 are easily detachable from the refrigerant gas supply port 52 and the refrigerant gas discharge port 54, respectively.

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

The valve stator 56 is fixed to the oscillation generating section case 46. The valve rotor 58 is coupled to the motor unit 48 and rotates about its central axis by driving the motor unit 48. In fig. 3, an arrow a1 indicates the direction of rotation. The bottom surface of the valve rotor 58 is in surface contact with the upper surface of the valve stator 56. As the motor portion 48 is rotationally driven, the bottom surface of the valve rotor 58 rotationally slides with respect to the upper surface of the valve stator 56.

In fig. 3, the flow direction of the refrigerant gas in the oscillating 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 a 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 30 b.

The valve portion 30 is configured such that the refrigerant gas chamber 28 is not connected to both the high-pressure line 24 and the low-pressure line 26. That is, the flow of refrigerant gas does not short-circuit between the high-pressure line 24 and the low-pressure line 26 through the oscillation start portion 16.

In the high-pressure state, the refrigerant gas is introduced from the high-pressure pipe 24 into the refrigerant gas chamber 28 through the high-pressure connection 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 (arrow a3) via the internal flow path of the valve portion 30, the refrigerant gas discharge port 54, and the low-pressure connection pipe 42, and the pressure in the refrigerant gas chamber 28 decreases.

Therefore, by continuously rotating the valve rotor 58 relative to the valve stator 56 based on the rotation of the motor portion 48, the high-pressure state and the low-pressure state of the refrigerant gas chamber 28 can be periodically alternately switched. Therefore, pressure oscillation 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 disposed in the high-pressure chamber 60 that communicates with the refrigerant gas supply port 52 and into which high-pressure refrigerant gas is introduced, but the present invention is not limited thereto. The valve rotor 58 may be disposed in a low-pressure chamber that communicates with the refrigerant gas discharge port 54 and into which low-pressure refrigerant gas is introduced.

The refrigerant gas flow path switching mechanism of the cryogenic refrigerator using the rotary valve as the valve portion 30 can adopt various known configurations, and therefore, further detailed description thereof is omitted in the present specification.

The vibration transmission unit 32 includes a vibration transducer 62 and a vibration output port 64. The vibration converter 62 is connected to the refrigerant gas chamber 28 so as to transmit the pressure vibration of the refrigerant gas, and converts the pressure vibration of the refrigerant gas into mechanical vibration corresponding to the pressure vibration. The vibration output port 64 is provided on the vibration transducer 62 so that the mechanical vibration is output from the vibration transducer 62 and transmitted to the vibration utilizing apparatus 34.

The vibration converter 62 includes a working fluid chamber 66, and the working fluid chamber 66 accommodates a working fluid different from the refrigerant gas and is connected to the refrigerant gas chamber 28 so that pressure vibration of the refrigerant gas is transmitted to the working fluid. The working fluid is, for example, air. In this case, the working fluid can be easily used. However, the working fluid may be other gases or liquids suitable for transmitting vibrations.

The vibration converter 62 further includes a piston 68 that separates the working fluid chamber 66 from the refrigerant gas chamber 28. The upper surface of the piston 68 is opposed to the bottom surface of the valve stator 56, and the refrigerant gas chamber 28 is defined by these two surfaces and the inner surface of the oscillation start portion housing 46. Therefore, the upper surface of the piston 68 receives the pressure of the refrigerant gas from the refrigerant gas chamber 28. The lower surface of the piston 68 and the inner surface of the oscillation section case 46 define a working fluid chamber 66, and the lower surface of the piston 68 receives the pressure of the working fluid from the working fluid chamber 66.

The piston 68 is movable by a pressure difference between the working fluid chamber 66 and the refrigerant gas chamber 28. The oscillating portion housing 46 slidably supports the piston 68, thereby guiding the movement of the piston 68. The average pressure of the working fluid contained in the working fluid chamber 66 is set to be substantially equal to the refrigerant gas pressure of the refrigerant gas chamber 28, for example.

Therefore, in the high-pressure state of the refrigerant gas chamber 28, the piston 68 moves in a direction away from the valve portion 30 (arrow a4), whereby the pressure of the working fluid chamber 66 also rises. In the low-pressure state of the refrigerant gas chamber, the piston 68 moves in a direction to approach the valve portion 30 (arrow a5), and thereby the pressure of the working fluid chamber 66 also drops. As such, the pressure vibration of the refrigerant gas in the refrigerant gas chamber 28 is transmitted to the working fluid of 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 restricting member 69 that restricts the movable range of the piston 68 may be provided on the inner surface of the oscillation start portion case 46. The piston 68 may also function as a seal for preventing or minimizing leakage of the refrigerant gas from the refrigerant gas chamber 28 to the working fluid chamber 66 and leakage of the working fluid from the working fluid chamber 66 to the refrigerant gas chamber 28, or a seal member for sealing such leakage of the refrigerant gas or the working fluid may be attached between the piston 68 and the vibration generating unit case 46.

The working fluid chamber 66 is coupled with 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 is not limited thereto. For example, instead of the movable partition wall like the piston 68 that transmits vibration by its own displacement, an elastically deformable flexible film 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 membrane member so that pressure vibration of the refrigerant gas is transmitted to the working fluid.

The vibration output port 64 is provided on the oscillation generating portion case 46 as an outlet for outputting vibration from the vibration transmitting portion 32 (i.e., the working fluid chamber 66) to the outside. For example, as shown in the drawing, the vibration output port 64 is provided at the bottom of the working fluid chamber 66, but the vibration output port 64 may be disposed at other positions of the working fluid chamber 66, for example, at a side wall portion or the like. The vibration output port 64 is configured to detachably mount the vibration transmission pipe 33. The vibration transmission pipe 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 utilizing apparatus 34 via the working fluid inside the vibration transmitting pipe 33. It is preferable that the working fluid in the vibration transmission pipe 33 is the same type of fluid (for example, air) as the working fluid in the working fluid chamber 66 because it is easier to use the working fluid.

The vibration output from the vibration starting portion 16 to the vibration utilizing apparatus 34 can be adjusted. For example, by changing the rotational speed of the motor portion 48, the frequency of the vibration can be directly changed, and the amplitude of the 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 can be changed, and the amplitude of the vibration can be changed. Further, by changing the design of the valve section 30 (for example, the arrangement, shape, etc. of the internal channel of the valve section 30), the amplitude and frequency of the vibration can also be adjusted.

In this manner, according to the cryogenic refrigerator system 10 of the embodiment, a desired vibration can be excited by the vibration excitation unit 16, and the desired vibration can be supplied to the vibration utilization device 34 (for example, a vibration pad of the MRE imaging apparatus).

The excitation unit 16 is smaller and simpler in structure than a conventionally known excitation device for MRE, and therefore, is advantageous from the viewpoints of space reduction, energy saving, manufacturing cost, and the like. One of the main reasons for this is that the vibration generator 16 can be additionally installed in the conventional cryogenic refrigerator having the compressor 12 and the cold head 14. Since the oscillation starting unit 16 can use the compressor 12 as a refrigerant gas source, it does not need a dedicated oscillation source having a complicated structure, unlike the conventional MRE excitation device. Further, since the original power supply (for example, the main power supply 45) can be used, an additional power supply is not required, and the power consumption is not increased at all or hardly.

Cryogenic refrigerators for the cooling of superconducting magnets are originally designed to be suitable for high magnetic field environments. As described above, the valve section 30, which is one of the main components of the vibration generating section 16, may be designed to have the same or similar structure as the valve section used in the conventional cryogenic refrigerator. Therefore, designing the valve portion 30 to be suitable for a high magnetic field environment is extremely easy for the manufacturer of the cryogenic refrigerator system 10 in particular. It is not particularly difficult to provide the other components of the oscillating portion 16 suitable for a high magnetic field environment. Therefore, the vibration starting portion 16 can be provided in a high magnetic field environment as in the case of the compressor 12 and the cold head 14.

Therefore, unlike the conventionally known excitation device for MRE, the excitation unit 16 can be disposed in the vicinity of the MRE imaging device within a limited in-range region. The vibration transmission distance from the vibration starting portion 16 to the vibration utilizing device 34 is considerably short, and therefore vibration can be transmitted efficiently. The transmission loss of the vibration is reduced, and the delay from the oscillation in the oscillation starting unit 16 to the vibration receiving of the subject is not caused or can be reduced to a level that does not have a significant influence.

The vibration generating unit 16 is configured as a unit that is detachably connected to the high-pressure line 24 and the low-pressure line 26 and can be transported. In this way, the oscillation starting unit 16 can be additionally provided in the cryogenic refrigerator after the next operation, which is very convenient. The vibration generator 16 can be transported to an existing cryogenic refrigerator and mounted as an accessory or an attachment of the cryogenic refrigerator.

Further, the oscillation starting portion 16 has an oscillation transducer 62 and an oscillation output port 64. The vibration converter 62 can convert the pressure vibration of the refrigerant gas into vibration of another medium, and thus can suppress a decrease in the refrigerant gas circulating through the cryogenic refrigerator system 10 (for example, leakage of the refrigerant gas). Further, the vibration output port 64 can be connected to the vibration utilizing device 34, and the vibration can be easily supplied to the vibration utilizing device 34 by a relatively simple operation.

By using the vibration converter 62 as the working fluid chamber 66, a more easily handled working fluid different from the refrigerant gas can be used as a medium for transmitting the vibration to the vibration utilizing device 34.

In the above embodiment, the cold head 14 stops operating during the operation of the vibration generating portion 16. Therefore, the cold head 14 does not affect the operation of the vibration generating section 16 and the vibration utilizing equipment 34. During the operation of the cold head 14, the oscillation generating portion 16 stops operating. Therefore, the operation of the oscillating portion 16 does not cause a decrease in the cooling performance of the cold head 14.

Fig. 4 is a schematic diagram showing another example of the vibration transmission section 32 of the excitation section 16 according to the embodiment. As in the above-described embodiment, the pressure vibration of the refrigerant gas in the refrigerant gas chamber 28 is transmitted to the vibration transmission portion 32. The vibration transducer 62 of the vibration transmission unit 32 may include a pressure transducer 70 disposed inside the working fluid chamber 66. The pressure converter 70 is configured to convert pressure vibration of the working fluid in the working fluid chamber 66 into electric vibration corresponding to the pressure vibration. In general, the pressure converter 70 is also referred to as a pressure transmitter (pressure transmitter) or a pressure transducer (pressure transducer), or the like.

The vibration output port 64 is provided on the vibration transducer 62 so that the electric vibration is output from the vibration transducer 62 and transmitted to the vibration utilizing apparatus 34. The pressure transducer 70 is electrically connected to the vibration output port 64, and the vibration output port 64 serves as an output terminal that outputs an electrical signal indicating electrical vibration generated by the pressure transducer 70 based on pressure vibration of the working fluid. Thus, the vibration output port 64 is connected to the vibration utilizing device 34 through the signal line 72, and an electric signal representing electric vibration can be output from the pressure transducer 70 to the vibration utilizing device 34 through the signal line 72.

With this configuration, the vibration transmission unit 32 can output vibration corresponding to the pressure vibration of the refrigerant gas to the outside. The vibration generating portion 16 can supply a desired vibration to the vibration utilizing device 34.

Fig. 5 is a schematic diagram showing another example of the vibration transmission section 32 of the excitation section 16 according to the embodiment. The oscillation generating portion 16 includes the refrigerant gas chamber 28, the valve portion 30, and the vibration transmitting portion 32, and they are accommodated in the oscillation generating portion case 46, as in the above-described embodiment. The vibration-starting portion 16 has a refrigerant gas supply port 52 connected to the high-pressure connection pipe 40 and a refrigerant gas discharge port 54 connected to the low-pressure connection pipe 42.

The vibration transmission unit 32 may include a vibration converter 62 disposed inside the refrigerant gas chamber 28 so that pressure vibration of the refrigerant gas is transmitted thereto, and converting the pressure vibration of the refrigerant gas into electric vibration corresponding to the pressure vibration, and a vibration output port 64 provided in the vibration converter 62 so that the electric vibration is output from the vibration converter 62 and transmitted to the vibration utilizing device 34. The vibration converter 62 may be a pressure converter 70 that is disposed in the refrigerant gas chamber 28 and converts pressure vibration of the refrigerant gas into electrical vibration. Pressure transducer 70 may be electrically connected to vibration output port 64, and vibration output port 64 may be connected to vibration utilizing device 34 via signal line 72.

With this configuration, the vibration transmission unit 32 can output vibration corresponding to the pressure vibration of the refrigerant gas to the outside. The vibration generating portion 16 can supply a desired vibration to the vibration utilizing device 34. In this case, the working fluid chamber 66 is not required, and thus the structure becomes simple.

The present invention has been described above with reference to the embodiments. However, it will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, various design changes can be made, and various modifications are possible and are within the scope of the present invention.

Various features that are described in one embodiment can also be applied to other embodiments. The new embodiment which is produced by the combination has the effects of the combined embodiments.

Industrial applicability

The present invention can be used in the fields of cryogenic refrigerator systems and vibrator units.

Description of the symbols

10-cryogenic refrigerator system, 12-compressor, 12 a-discharge port, 12 b-suction port, 14-cold head, 14 a-high pressure port, 14 b-low pressure port, 16-vibration starting portion, 24-high pressure line, 26-low pressure line, 28-refrigerant gas chamber, 30-valve portion, 32-vibration transmission portion, 34-vibration utilizing device, 62-vibration converter, 64-vibration output port, 66-working fluid chamber, 70-pressure converter.