JPH09229503A - Cryogenic freezer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a freezing capability of a pre-freezing device and a shield freezing device to be adjusted while the same freezing devices are being operated without changing a capacity or a specification of each of the freezing devices in the case that the pre-freezing device and the shield freezing device for a JT (Joule-Thomson) freezer connected in parallel with a compressor are operated in multi-mode. SOLUTION: In the case that a displacer driving frequency of each of freezers 26, 40 is made variable and an inner pressure of a buffer tank Tb acting as a freezing load of a JT(Joule-Thomson) freezer 51 is decreased lower than a set value, the displacer driving frequency of the pre-cooling freezer 26 is decreased and a displacer driving frequency of the shield freezer 40 is increased to reduce a freezing capability of the Joule-Thomson freezer 51, and in turn in the case that an inner pressure in the tank Tb is decreased lower than the set value, the displacer driving frequency of the pre-cooling freezer 26 is increased and the displacer driving frequency of the shield freezer 40 is decreased to cause a freezing capability of the Joule-Thomson freezer 40 to be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic refrigeration system in which a plurality of refrigerators, which are expanders, are connected to a compressor, and particularly, the capacity of each refrigerator is variably controlled individually. Belongs to the technical field of things.

[0002]

2. Description of the Related Art Conventionally, as a cryogenic refrigerating apparatus of this type, one compressor for compressing a refrigerant gas is subjected to adiabatic expansion of the refrigerant gas from the compressor by reciprocating movement of a displacer to achieve cryogenic temperatures. Multiple refrigerators (expanders) to generate
There are known multi-types in which the refrigerators are connected in parallel and the refrigerators are simultaneously operated in multi-operation (for example, JP-A-3-15677, JP-A-1-210765, JP-A-5-87414, (See each publication of Hei 6-68422 and Jitsukaihei 5-47761).

In addition, it is known to change the driving frequency of the reciprocating motion of the displacer in the refrigerator so as to change the capacity of the refrigerator (for example, Japanese Patent Laid-Open No. 261094/1990). Kosho 3-509
56, JP-A-63-306361, JP-A-6-10
1917, JP-A-3-152353, and Shokai 62.
See each publication of No. 112074). In addition, Japanese Examined Japanese Patent Sho 61
In JP-A-60348, a gas pressure drive type refrigerator that reciprocates the displacer by the refrigerant gas pressure to the displacer is provided with a variable orifice for changing the refrigerant gas pressure to the displacer by changing the opening degree. The reciprocating movement of the displacer is adjusted by controlling the opening of the variable orifice.

[0004]

When a plurality of refrigerators are connected to a compressor for multi-operation as in the former conventional example, the refrigerating capacity of each refrigerator is different from that of other refrigerators. If it is decided uniformly according to the combination, and the refrigerating capacity of each refrigerator is different, it is necessary to change the specifications of the refrigerator in advance, and when changing the refrigerating capacity of the refrigerator, The capacity of the refrigerator must be changed each time.

The present invention has been made in view of the above circumstances, and an object thereof is to push the idea of the latter prior art described above in the case of connecting a plurality of refrigerators to a compressor in parallel and performing a multi-operation. Thus, the refrigerating capacity of each refrigerator can be adjusted while using the same refrigerator without changing the capacity or changing the specifications.

[0006]

In order to achieve the above object, the present invention provides at least one of a multi-type cryogenic refrigerating system in which a plurality of refrigerators are connected to a compressor to perform a multi-operation. The displacer drive frequency of each refrigerator and the flow rate of the refrigerant to the refrigerator were made variable.

Specifically, as shown in FIG.
In the invention, at least one compressor that compresses the refrigerant gas and a plurality of refrigeration units that are connected in parallel to the compressor and that expand the refrigerant gas from the compressor by the reciprocating motion of the displacer to generate cryogenic temperature. In a cryogenic refrigeration system including the machines (26) and (40), a displacer drive frequency varying means for varying the reciprocating drive frequency of the displacer of the at least one refrigerator (26) and (40) ( 72) is provided.

With the above construction, the displacer drive frequency of at least one of the plurality of refrigerators (26), (40) is changed to the displacer drive frequency varying means (7).
2), the refrigerator (2
The refrigerating capacity of the refrigerators (26) and (40) can be changed by changing the displacer drive frequency of 6) and (40). As a result, a plurality of refrigerators (26),
The capacity distribution among (40) can be changed, and individual refrigerators (2
According to the refrigerating capacity of 6) and (40), a wide range of adjustment can be performed without the need to change the capacity.

According to a second aspect of the invention, in the cryogenic refrigerator of the first aspect of the invention, a plurality of refrigerators (26), (4) are provided.
0) is a JT that generates cryogenic temperature by the Joule-Thomson expansion of the high pressure refrigerant gas from the compressor at the JT valve (58).
A precooling refrigerator (26) attached to the refrigerator (51) and precooling the high-pressure refrigerant gas before the Joule-Thomson expansion.
And a shield refrigerator (4) which shields at least the cryogenic cooling portion of the JT refrigerator (51) from the outside.
0) and.

As a result, even when the pre-cooling refrigerator (26) and the shield refrigerator (40) of the JT refrigerator (51) are multi-operated, the refrigerating capacity of the pre-cooling refrigerator (26), that is, the JT refrigerator (51). And the refrigerators (26) and (40) having the same specifications as the capacity distribution between the refrigerating capacity of the shield refrigerator (40)
Can be adjusted using the refrigerator (26), (4
It is possible to meet various demands for refrigerating capacity without changing the specification of 0).

According to a third aspect of the invention, in the cryogenic refrigeration system of the second aspect, the compressor comprises a low-stage compressor (5) for compressing a refrigerant gas, and a discharge from the low-stage compressor (5). And a high-stage compressor (8) for compressing the generated refrigerant gas, and the pre-cooling and shield refrigerators (26) and (40) are
It is assumed that the refrigerant gas discharged from the high-stage compressor (8) is expanded. Claim 4
In the invention of claim 1, the compressor is a pre-cooling and shield refrigerator (2
Refrigerator compressor (18) for supplying refrigerant gas to 6) and (40) and JT for supplying refrigerant gas to JT valve (58)
And a compressor (19) for use. According to these inventions, the precooling and shield refrigerator (26), (40)
The connection structure of the compressor connected to the can be embodied.

According to a fifth aspect of the invention, in the cryogenic refrigeration system of the third aspect, the low-stage and high-stage compressors (5),
The operating frequency of (8) is independently variable. Further, in the invention of claim 6, in the cryogenic refrigerator of the invention of claim 4, the operating frequencies of the compressors (18), (19) for the refrigerator and the compressor for JT are independently variable. According to these inventions, not only the displacer driving frequency of the refrigerators (26) and (40) but also the operating frequency of the compressor can be changed. Therefore, by changing both, the pre-cooling refrigerator (2
6) The capacity distribution between the refrigerating capacity of the (JT refrigerator (51)) and the refrigerating capacity of the shield refrigerator (40) can be adjusted over a wider range to meet a large demand for refrigerating capacity.

In the invention of claim 7, as shown in FIG. 5, as in the invention of claim 1, at least one compressor for compressing the refrigerant gas and the compressor connected in parallel to the compressor, It is premised on a cryogenic refrigerator provided with a plurality of refrigerators (26) and (40) for expanding a refrigerant gas from and generating cryogenic temperature. A refrigerant flow rate adjusting means (46) for adjusting the flow rate of the refrigerant gas to the at least one refrigerator (26), (40) is provided.

With this configuration, the refrigerant flow rate adjusting means (4
Since the flow rate of the refrigerant gas to at least one of the plurality of refrigerators (26) and (40) is made variable by 6), the refrigerant gas flow rate to the refrigerators (26) and (40) can be changed. By changing the refrigerating capacity, the refrigerating capacity can be changed. Therefore, like the invention of claim 1, the capacity distribution among a plurality of refrigerators (26), (40) is changed to change the refrigerating capacity of each refrigerator (26). ), (40) according to the refrigerating capacity, it is possible to perform a wide range of adjustments without the need to change the capacity.

According to an eighth aspect of the invention, in the cryogenic refrigeration system of the seventh aspect of the invention, as in the second aspect of the invention, the plurality of refrigerators (26), (40) are high pressure from the compressor. A pre-cooling refrigerator (26) attached to a JT refrigerator (51) that generates cryogenic temperature by Joule-Thomson expansion of the refrigerant gas at the JT valve (58) and pre-cooling the high-pressure refrigerant gas before the Joule-Thomson expansion. At least the shield refrigerator (40) for heat shielding the cryogenic cooling portion of the JT refrigerator (51) from the outside. Therefore, the same effect as that of the second aspect of the invention can be obtained.

According to a ninth aspect of the invention, in the cryogenic refrigeration system of the eighth aspect of the invention, as in the third aspect of the invention, the compressor is a low-stage compressor (5) for compressing a refrigerant gas, and With the high-stage compressor (8) for compressing the refrigerant gas discharged from the low-stage compressor (5), the pre-cooling and shield refrigerator (2)
It is assumed that 6) and (40) are configured to expand the refrigerant gas discharged from the high stage compressor (8). Even in this case, the same effect as the invention of claim 3 can be obtained.

According to a tenth aspect of the invention, in the cryogenic refrigeration system of the eighth aspect of the invention, as in the fourth aspect of the invention, the compressor is used as a precooling and shield refrigerator (26), (40) with a refrigerant gas. A compressor (18) for a refrigerator that supplies the refrigerant and a compressor (19) for the JT that supplies a refrigerant gas to the JT valve (58). In this invention, the same effect as that of the invention of claim 4 can be obtained.

According to the eleventh aspect of the invention, in the cryogenic refrigeration system of the ninth aspect, the operating frequencies of the low-stage and high-stage compressors (5) and (8) are independent, as in the fifth aspect of the invention. And make it variable. In the invention of claim 12, claim 1
In the cryogenic refrigerating apparatus of the invention of No. 0, the compressors (18), (19) for the refrigerator and the JT are the same as those of the invention of claim 6.
The operating frequency of is independently variable. According to these inventions, the same operational effects as those of the invention of claim 4 or 5 can be obtained.

In the thirteenth aspect of the invention, as shown in FIGS. 1 and 4, in the cryogenic refrigeration system of the first aspect of the invention, each of the refrigerators (26) and (40) uses a displacer as a refrigerant gas. A gas pressure drive type refrigerator driven by pressure is provided with a variable orifice that changes the refrigerant gas pressure for the displacer to adjust the movement of the displacer. Then, the opening of the variable orifice is configured to be controlled according to the change of the displacer driving frequency.

With this structure, the refrigerator (26),
The opening of the variable orifice can be controlled to the optimum opening according to the change of the displacer drive frequency of (40),
Not only the displacer drive frequency of the refrigerators (26) and (40) but also the refrigerant gas pressure to the displacer is changed to an appropriate pressure so that the refrigerating capacity of the pre-cooling refrigerator (26) and the refrigerating capacity of the shield refrigerator (40). The capacity distribution can be adjusted over a wider range to meet the demand for large refrigeration capacity.

[0021] The fourteenth and following aspects of the invention embody a control mode of the displacer drive frequency of the refrigerator and the flow rate of the refrigerant to the refrigerator. That is, in the invention of claim 14, as shown in FIG. 1, in the cryogenic refrigerator of the invention of claim 3 or 4, JT refrigerator load detecting means (for detecting the refrigerating load of the JT refrigerator (51) ( 74) and the JT detected by the JT refrigerator load detection means (74)
When the refrigerating load of the refrigerator (51) becomes lower than a set value, at least one of the displacer driving frequency of the precooling refrigerator (26) and the displacer driving frequency of the shield refrigerator (40) is increased. , When the refrigerating load of the JT refrigerator (51) exceeds the set value, at least one of increasing the displacer driving frequency of the precooling refrigerator (26) or decreasing the displacer driving frequency of the shield refrigerator (40) is performed. And a control means (71) for controlling the displacer drive frequency changing means (72).

With this structure, the refrigerating load of the JT refrigerator (51) is detected by the JT refrigerator load detecting means (74), and the displacer drive frequency varying means (72) is detected according to the refrigerating load of the JT refrigerator (51). ) Is the control means (7
When the displacer drive frequency of the refrigerator is changed under the control of 1) and the refrigeration load of the JT refrigerator (51) is lower than the set value, the displacer drive frequency of the precooler (26) is reduced or the shield refrigerator is used. At least one of the displacer drive frequencies of (40) is increased, and the refrigerating capacity of the precooling refrigerator (26), that is, the JT refrigerator (51) is reduced. On the other hand, when the refrigeration load of the JT refrigerator (51) exceeds the set value, the pre-cooling refrigerator (2
At least one of increasing the displacer driving frequency of 6) and decreasing the displacer driving frequency of the shield refrigerator (40) is performed, and the refrigerating capacity of the JT refrigerator (51) is increased. In this way, even if the load of the JT refrigerator (51) changes during the multi-operation of the cryogenic refrigerator, the refrigerating capacity of all the refrigerators does not change uniformly in the same way.
The refrigerating capacity can be changed according to the load, and for example, the refrigerating capacity of the JT refrigerator (51) can be changed while keeping the refrigerating capacity of the shield refrigerator (40) substantially constant. A wide range of capability control of (51) can be performed.

According to a fifteenth aspect of the present invention, in the cryogenic refrigeration system of the fourteenth aspect, the operating frequency of the compressor (8) for supplying the high pressure refrigerant gas to the precooling and shield refrigerators (26) and (40) is set. It is variable. The control means (71) then precools and shields the refrigerator (26), (4
0), the operating frequency of the compressor (8) that supplies high-pressure refrigerant gas, while the operating frequency of the compressor (8) decreases when the refrigerating load of the JT refrigerator (51) drops below a set value,
When the refrigeration load of the JT refrigerator (51) exceeds the set value, the operation frequency of the compressor (8) is controlled to increase.

In this way, in the control means (71), the operating frequency of the compressor (8) for supplying the high pressure refrigerant gas to the precooling and shield refrigerators (26) and (40) is the same as that of the JT refrigerator (51). It can be controlled and changed according to the refrigeration load,
When the operating frequency of the compressor (8) is lowered when the refrigerating load of the JT refrigerator (51) is lower than the set value, while the refrigerating load of the JT refrigerator (51) is higher than the set value. Then, the operating frequency of the compressor (8) is increased.
In this way, not only the displacer drive frequency of the refrigerators (26) and (40) but also the operating frequency of the compressor (8) can be changed, so that the JT refrigerator (5
The refrigerating capacity can be largely changed according to the change in the load of 1), and a wider range of capacity control of the JT refrigerator (51) can be performed.

In the sixteenth aspect of the present invention, the fourteenth or first aspect is provided.
In the cryogenic refrigeration system of the invention of 5, the JT high pressure adjusting means (1) for adjusting the pressure of the refrigerant gas to the JT valve (58).
3) is provided, and the control means (71) is the JT refrigerator (51).
When the refrigeration load on the JT valve (5
Refrigerant gas pressure to 8) decreases while JT refrigerator (51)
When the refrigeration load on the JT valve (5
The JT high pressure adjusting means (13) is controlled so that the refrigerant gas pressure to 8) rises.

In the present invention, J is controlled by the control means (71).
The JT high pressure adjusting means (13) is controlled according to the refrigerating load of the T refrigerator (51), the pressure of the refrigerant gas to the JT valve (58) is adjusted, and the refrigerating load of the JT refrigerator (51) is set to a set value. When the temperature is lower than that, the refrigerant gas pressure to the JT valve (58) is lowered, the refrigerating capacity of the JT refrigerator (51) is reduced, and the refrigeration load of the JT refrigerator (51) is larger than the set value. At times, the refrigerant gas pressure to the JT valve (58) rises, and the refrigerating capacity of the JT refrigerator (51) increases. Therefore, even in this case, the refrigerating capacity can be greatly changed according to the change in the load of the JT refrigerator (51), and a wider range of capacity control of the JT refrigerator (51) can be performed.

According to a seventeenth aspect of the present invention, in the cryogenic refrigeration system of the sixteenth aspect, the low-stage compressor (5) or JT is used.
The operating frequency of the compressor (19) is variable. And
The control means (71) controls the operating frequencies of the compressors (5) and (19) of the compressors (5) and (19) when the refrigerating load of the JT refrigerator (51) is lower than a set value. While the operating frequency decreases, the operating frequency of the compressors (5) and (19) is controlled to increase when the refrigerating load of the JT refrigerator (51) increases above the set value.

As a result, the control means (71) causes the JT
The operating frequency of the low-stage compressor (5) or the JT compressor (19) is controlled according to the refrigeration load of the refrigerator (51),
When the refrigerating load of the refrigerator (51) becomes lower than the set value, the operating frequencies of the compressors (5), (19) decrease, and J
When the refrigerating capacity of the JT refrigerator (51) increases while the refrigerating capacity of the T refrigerator (51) decreases,
The operating frequencies of the compressors (5) and (19) increase, and the refrigerating capacity of the JT refrigerator (51) increases. Therefore, even in this case, the refrigerating capacity can be largely changed according to the change in the load of the JT refrigerator (51), and a wider range of capacity control of the JT refrigerator (51) can be performed.

In the eighteenth aspect of the invention, as shown in FIG.
In the cryogenic refrigerator according to claim 9 or 10, the JT refrigerator load detecting means (74) for detecting the refrigerating load of the JT refrigerator (51), and the JT like the invention of claim 14.
When the refrigerating load of the JT refrigerator (51) detected by the refrigerator load detecting means (74) is lower than a set value,
The refrigerant gas flow rate to the pre-cooling refrigerator (26) decreases, while the refrigerant gas flow rate to the shield refrigerator (40) decreases when the refrigerating load of the JT refrigerator (51) increases above a set value. A control means (71) for controlling the flow rate adjusting means (46) is provided.

With this configuration, the refrigerating load of the JT refrigerator (51) is detected by the JT refrigerator load detecting means (74), and the refrigerant flow rate adjusting means (46) according to the refrigerating load of the JT refrigerator (51). ) Is controlled by the control means (71),
When the refrigerating load of the JT refrigerator (51) is lower than the set value, the refrigerant gas flow rate to the pre-cooling refrigerator (26) is reduced and the refrigerating capacity of the JT refrigerator (51) is reduced. When the refrigerating load of (51) exceeds the set value, the refrigerant gas flow rate to the shield refrigerator (40) is reduced and its refrigerating capacity is reduced, and the refrigerant flow rate to the precooling refrigerator (26) is correspondingly reduced. And its refrigerating capacity increases. Therefore, even in this case, as in the case of the fourteenth aspect of the present invention, it is possible to perform a wide capacity control of the refrigerating capacity of the JT refrigerator (51).

In the nineteenth aspect of the invention, in the cryogenic refrigeration system of the eighteenth aspect of the invention, as in the fifteenth aspect of the invention, a high pressure refrigerant gas is supplied to the precooling and shield refrigerators (26) and (40). The operating frequency of the compressor (8) is variable. Then, the control means (71) sets the operating frequency of the compressor (8) that supplies high-pressure refrigerant gas to the precooling and shield refrigerators (26) and (40) by the refrigerating load of the JT refrigerator (51). The operating frequency of the compressor (8) decreases when the value decreases below the value, while the operating frequency of the compressor (8) increases when the refrigeration load of the JT refrigerator (51) increases above the set value. The configuration is

In this way, the operating frequency of the compressor (8) is controlled by the control means (7) according to the refrigerating load of the JT refrigerator (51).
1), when the refrigeration load of the JT refrigerator (51) falls below a set value, the precooling and shield refrigerator (2
Compressor (8) for supplying high pressure refrigerant gas to 6) and (40)
When the refrigeration load of the JT refrigerator (51) increases more than the set value while the operating frequency of the compressor is reduced, the compressor (8)
The operating frequency of is increased. Therefore, it is possible to obtain the same effects as the invention of claim 15.

According to a twentieth aspect of the invention, in the cryogenic refrigeration system of the nineteenth aspect of the invention, JT high pressure adjusting means (13) for adjusting the pressure of the refrigerant gas to the JT valve (58) is provided, and the control means (71). When the refrigerating load of the JT refrigerator (51) is lower than the set value, the refrigerant gas pressure to the JT valve (58) is lowered, while the refrigerating load of the JT refrigerator (51) is higher than the set value. The JT high pressure adjusting means (1) so that the refrigerant gas pressure to the JT valve (58) rises when
3) is controlled.

Also in this invention, J is controlled by the control means (71).
The JT high pressure adjusting means (13) is controlled according to the refrigerating load of the T refrigerator (51), the pressure of the refrigerant gas to the JT valve (58) is adjusted, and the refrigerating load of the JT refrigerator (51) is set to a set value. When the refrigerating load of the JT refrigerator (51) increases more than the set value, the refrigerant gas pressure to the JT valve (58) decreases and the refrigerating capacity decreases.
The refrigerant gas pressure to the T valve (58) rises, and the refrigerating capacity increases. Therefore, the same effect as that of the sixteenth aspect of the invention can be obtained.

According to the invention of claim 21, in the cryogenic refrigeration system of the invention of claim 20, the operating frequency of the low-stage compressor (5) or the compressor for JT (19) is set in the same manner as the invention of claim 17. The control means (71) is variable, and the operating frequencies of the compressors (5) and (19) are set to the JT refrigerator (51).
When the refrigerating load of the JT refrigerator (51) is higher than the set value, the operating frequencies of the compressors (5) and (19) are lowered when the refrigerating load of the JT refrigerator (5) and (19) is lower than the set value. ) And (19) are controlled so as to increase the operating frequency.

In this case, when the refrigerating load of the JT refrigerator (51) is lower than the set value, the operating frequency of the low stage compressor (5) or the JT compressor (19) is lowered and the JT refrigerator ( While the refrigerating capacity of 51) decreases, the JT refrigerator (5
When the refrigeration load of 1) exceeds the set value, the operating frequencies of the compressors (5) and (19) increase, and the refrigerating capacity of the JT refrigerator (51) increases. Therefore, the same operational effect as that of the seventeenth aspect of the invention can be obtained.

In the twenty-second aspect of the invention, as shown in FIG. 10, in the cryogenic refrigeration system of the third or fourth aspect of the invention,
Shield refrigerator load detecting means (76) for detecting the refrigerating load of the shield refrigerator (40) and precooling when the refrigerating load detected by the shield refrigerator load detecting means (76) falls below a set value. At least one of increasing the displacer drive frequency of the refrigerator (26) and decreasing the displacer drive frequency of the shield refrigerator (40) is performed, and when the refrigerating load rises above a set value, the precooling refrigerator (26 The control means (71) for controlling the displacer drive frequency changing means (72) is provided so that at least one of the decrease of the displacer drive frequency of (1) and the increase of the displacer drive frequency of the shield refrigerator (40) is performed.

With this configuration, the shield refrigerator (40)
Of the refrigerator (26), (40). ) Is changed and the refrigerating load of the shield refrigerator (40) is lower than the set value, the displacer driving frequency of the precooling refrigerator (26) is increased or the displacer driving frequency of the shield refrigerator (40) is increased. Of the shield refrigerator (40) is reduced. On the other hand, when the refrigerating load of the shield refrigerator (40) exceeds the set value, at least one of the decrease of the displacer driving frequency of the precooling refrigerator (26) and the increase of the displacer driving frequency of the shield refrigerator (40) occurs. Then, the refrigerating capacity of the refrigerator (40) is increased. In this way, even if the load of the shield refrigerator (40) changes during the multi-operation of the cryogenic refrigerator, the refrigerating capacities of all the refrigerators do not change uniformly in the same manner, and the refrigerating capacity varies depending on the load. The capacity can be changed, and for example, the refrigerating capacity of the shield refrigerator (40) can be changed while keeping the refrigerating capacity of the JT refrigerator (51) substantially constant. Ability control can be performed.

In the twenty-third aspect of the invention, in the cryogenic refrigeration system of the twenty-second aspect of the invention, as in the fifteenth aspect of the invention, the high-pressure refrigerant gas is supplied to the precooling and shield refrigerators (26) and (40). The operating frequency of the compressor (8) is variable. Then, the control means (71) sets the operating frequency of the compressor (8) for supplying the high-pressure refrigerant gas to the precooling and shield refrigerators (26) and (40) to the shield refrigerator (4).
The operating frequency of the compressor (8) is lowered when the refrigerating load of 0) is lower than the set value, while the operating frequency of the compressor (8) is raised when the refrigerating load is higher than the set value. Controlled.

By doing so, the shield refrigerator (40)
The operating frequency of the compressor (8) is controlled by the control means (71) according to the refrigerating load of the precooling and the shield refrigerating machine (26) when the refrigerating load of the shield refrigerator (40) is lower than a set value. ), (40), the operating frequency of the compressor (8) that supplies the high-pressure refrigerant gas is reduced, while when the refrigeration load of the shield refrigerator (40) increases above the set value, the compressor (8) The operating frequency is increased. In this way, not only the displacer drive frequency of the refrigerators (26) and (40) but also the operating frequency of the compressor (8) can be changed, so the shield refrigerator (40) during multi-operation of the refrigerating apparatus.
The refrigerating capacity can be greatly changed according to the change in the load of the above, and a wider range of capacity control of the shield refrigerator (40) can be performed.

According to a twenty-fourth aspect of the invention, as shown in FIG. 11, in the cryogenic refrigeration system of the ninth or tenth aspect of the invention, a shield refrigerator load detecting means (for detecting the refrigerating load of the shield refrigerator (40) ( 76) and when the refrigeration load detected by the shield refrigerator load detecting means (76) falls below a set value, the shield refrigerator (4)
0)) while the refrigerant gas flow rate decreases while the refrigeration load rises above the set value, the precooling refrigerator (26)
And a control means (71) for controlling the refrigerant flow rate adjusting means (46) so that the refrigerant gas flow rate with respect to the.

With this configuration, the shield refrigerator (40)
Is detected by the shield refrigerator load detecting means (76), and the refrigerant flow rate adjusting means (46) is controlled by the control means (71) according to the refrigerator load of the shield refrigerator (40).
When the refrigerating load of the shield refrigerator (40) is lower than the set value, the refrigerant gas flow rate to the shield refrigerator (40) is reduced to lower the refrigerating capacity, while the shield refrigerator (40) is controlled. When the refrigerating load of 4) exceeds the set value, the refrigerant gas flow rate to the pre-cooling refrigerator (26) is reduced, and the refrigerating capacity of the shield refrigerator (40) is reduced. Therefore, even in this case, claim 22
In the same manner as in the above invention, a wide range of capacity control of the refrigerating capacity of the shield refrigerator (40) can be performed.

According to a twenty-fifth aspect of the invention, in the cryogenic refrigeration system of the twenty-fourth aspect, the operating frequency of the compressor (8) for supplying the high-pressure refrigerant gas to the pre-cooling and shield refrigerators (26), (40) is The control means (71) is variable,
When the refrigeration load of the shield refrigerator (40) drops below the set value, the operating frequency of the compressor (8) that supplies high-pressure refrigerant gas to the pre-cooling and shield refrigerators (26) and (40) is reduced. While the operating frequency of 8) decreases, the operating frequency of the compressor (8) is controlled to increase when the refrigerating load exceeds the set value.

In this way, the operating frequency of the compressor (8) is controlled and changed by the control means (71) according to the refrigerating load of the shield refrigerator (40), and the shield refrigerator (4)
When the refrigeration load of 0) is lower than the set value, the operating frequency of the compressor (8) that supplies high-pressure refrigerant gas to the precooling and shield refrigerators (26) and (40) is lowered,
When the refrigeration load of the shield refrigerator (40) exceeds the set value, the operating frequency of the compressor (8) is increased.
Therefore, it is possible to obtain the same effect as that of the invention of claim 23.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 shows the entire configuration of a cryogenic refrigerator (R) according to Embodiment 1 of the present invention.
Is for cooling the superconducting magnet (M) so that the superconducting coil has a cryogenic level, and is attached to a liquid helium tank (Th) for storing liquid helium (refrigerant). Then, the superconducting magnet (M) is dipped in the helium tank (Th) and accommodated therein, and the liquid helium cools and holds the superconducting coil of the magnet (M) below the critical temperature.

The refrigerator (R) comprises a compressor unit (1) and a refrigerator unit (21). A low-stage compressor (5) for sucking and compressing low-pressure helium gas from the low-pressure gas suction port (2) into the compressor unit (1) through a low-pressure pipe (4) having a check valve (3). ) And the helium gas discharged from the low-stage compressor (5) together with the intermediate-pressure helium gas sucked from the intermediate-pressure gas suction port (6) through the intermediate-pressure pipe (7) to further increase the pressure. And a high-stage compressor (8) for compressing the high-pressure compressor (8), and the discharge side of the high-stage compressor (8) is connected to the high-pressure gas discharge port (10) for the refrigerator via the high-pressure pipe (9) for the refrigerator. Further, they are respectively connected to the JT high pressure gas discharge port (12) via the JT high pressure pipe (11) branched from the refrigerator high pressure pipe (9). The high-stage compressor (8) is composed of an inverter type compressor whose operating frequency is variable, and its operating frequency is independently variable.

The above-mentioned JT high-pressure pipe (11) is
And the second branch pipes (11a) and (11b) in parallel, and the first branch pipe (11a) is provided with a throttle-fixed first flow rate adjusting valve (V1) for flow rate adjustment, and 1st flow control valve (V1) which consists of solenoid valve on compressor discharge side
An on-off valve (AV1) is provided. On the other hand, the same second flow rate adjusting valve (V2) and second open / close valve (AV2) are respectively arranged in the second branch pipe (11b), and the opening degree of this second flow rate adjusting valve (V2) is Unlike the first flow rate adjusting valve (V1), for example, the opening is set smaller than that of the first flow rate adjusting valve (V1). In this embodiment, the high-stage compressor (8) is constituted by the first and second flow rate adjusting valves (V1), (V2) and the first and second on-off valves (AV1), (AV2).
Helium gas pressure (J) to the JT valve (58) by changing the opening of the high pressure pipe (11) from the
A JT high pressure adjusting mechanism (13) for adjusting the T high pressure is configured. For example, when the first opening / closing valve (AV1) is opened and the second opening / closing valve (AV2) is closed, the flow rate of helium gas is increased to increase the JT high pressure. While lowering, on the contrary, the first on-off valve (AV
When 1) is closed and the second opening / closing valve (AV2) is opened, the flow rate of helium gas is reduced to increase the JT high pressure.

Further, (Tb) is a buffer tank for storing helium gas, and one end of a helium gas supply / discharge pipe (15) is connected to the buffer tank (Tb). The other end of the helium gas supply / discharge pipe (15) is branched into a helium gas supply pipe (16) and a helium gas return pipe (17) in the compressor unit (1), and the helium gas supply pipe (16) The end is the low-stage compressor (5)
This helium gas supply pipe (16) is connected to the low-pressure pipe (4) between the suction side of the and the low-pressure gas suction port (2).
A low pressure control valve (LPR) is provided in the. This low pressure control valve (LPR) automatically opens as a pilot pressure when the pressure of helium gas in the low pressure pipe (4) drops below a set pressure.
Helium gas in the buffer tank (Tb) is supplied to the low-pressure pipe (4) (refrigerant circuit) as the valve R) is opened.

On the other hand, the end of the helium gas return pipe (17) is connected to the high pressure pipe (9) for the refrigerator (high pressure pipe for JT (1
1)) connected to this helium gas return pipe (17)
A high pressure control valve (HPR) is arranged in the middle of. This high-pressure control valve (HPR) automatically opens as a pilot pressure when the pressure of the helium gas in the refrigerator high-pressure pipe (9) rises above a set pressure. This high-pressure control valve (HPR) ) High pressure piping for refrigerator by opening the valve (9)
And the helium gas in the JT high-pressure pipe (11) (refrigerant circuit) is returned to the buffer tank (Tb).

On the other hand, the refrigerator unit (21)
Has a vacuum dewar (D), and this vacuum dewar (D)
The liquid helium tank (Th) is housed inside in a state of being thermally shielded from the outside by a heat shield plate (S).
It is a cryogenic cooling portion cooled to a cryogenic level by the refrigerator (51).

A liquid nitrogen tank (Tn) for storing liquid nitrogen is arranged inside the vacuum dewar (D). One end of a nitrogen pipe (22) is connected to the bottom of the liquid nitrogen tank (Tn), and the other end of the nitrogen pipe (22) is opened at the top of the same liquid nitrogen tank (Tn). Nitrogen piping (22) and liquid nitrogen tank (T
n) forms a closed circuit nitrogen circuit.

A shield plate heat exchanger (23), which is in contact with the heat shield plate (S) in a heat transferable manner, is disposed in the middle of the nitrogen pipe (22), and the liquid nitrogen tank (Tn) is provided. The liquid nitrogen in the inside is supplied to the shield plate heat exchanger (23) through the nitrogen pipe (22), and the heat exchanger (2
By heat exchange in 3), the heat shield plate (S) is cooled to the temperature of liquid nitrogen (about 80 K) to shield the liquid helium tank (Th) in the heat shield plate (S) from the outside, and The nitrogen gas evaporated by heat exchange in the shield plate heat exchanger (23) is returned to the nitrogen tank (Tn). Reference numeral (24) is an atmosphere release valve connected to the nitrogen pipe (22) for releasing excess nitrogen in the liquid nitrogen tank (Tn) to the outside of the vacuum dewar (D).

The refrigerator unit (21) is connected to the high-stage compressor (8) of the compressor unit (1) in parallel with each other in a closed circuit to form a precooling refrigerator (26) and a shield refrigerator (40). And a JT refrigerator (51). The pre-cooling refrigerator (26) compresses and expands the helium gas in order to pre-cool the helium gas (refrigerant) in the JT refrigerator (51). It is composed of a reciprocating gas pressure drive type GM (Gifford McMahon) cycle expander.

This pre-cooling refrigerator (26) is a hermetic motor head (2) arranged outside the vacuum dewar (D).
7) and a cylinder (28) of large and small two-stage structure connected to the motor head (27). A high pressure gas inlet (29) and a low pressure gas outlet (30) are opened in the motor head (27), and the high pressure gas inlet (29) is connected through a precooling side branch high pressure pipe (31) and a collective high pressure pipe (33). A compressor high pressure gas discharge port (10) of the compressor unit (1) and a low pressure gas outlet (30) of the compressor unit via a precooling side branch intermediate pressure pipe (34) and a collective intermediate pressure pipe (36). It is connected to the intermediate pressure gas suction port (6) of the unit (1).

On the other hand, the front end of the cylinder (28) penetrates the side wall of the vacuum dewar (D) and extends into the heat shield plate (S) therein, and the front end of the large diameter part thereof has a predetermined temperature level. The first heat station (3
7) and the tip of the small diameter portion is formed in the second heat station (38) which is cooled and held at a temperature level lower than that of the first heat station (37).

That is, although not shown here, in the cylinder (28), each of the above heat stations (3
Free type displacers (replacers) that partition and form expansion spaces are reciprocally fitted at positions corresponding to 7) and (38). On the other hand, the motor head (2
In 7), a rotary valve that opens and closes each time it rotates,
A valve motor for driving the rotary valve is housed. The rotary valve includes the high pressure gas inlet (29).
The helium gas flowing in from is supplied to each expansion space in the cylinder (28), or the helium gas expanded in each expansion space is switched to be discharged from the low pressure gas outlet (30). Further, the motor head (27) has a cylinder (2
8) An intermediate pressure chamber that communicates with the expansion space inside through a variable orifice whose opening can be adjusted from the outside is provided.
A pressure difference is generated between the expansion space and the intermediate pressure chamber by switching the rotary valve, and the displacer is reciprocally driven by this pressure difference, and the movement of the displacer is adjusted by changing the opening of the variable orifice. (Note that the variable orifice may be provided in the middle of the low-pressure or high-pressure helium gas pipe). Then, by opening and closing the rotary valve, the high pressure helium gas from the high stage compressor (8) of the compressor unit (1) is Simon expanded in each expansion space in the cylinder (28),
Cryogenic cold is generated by the temperature drop accompanying the expansion, and the cold is held by the first and second heat stations (37) and (38) in the cylinder (28). That is, in the pre-cooling refrigerator (26), the high-pressure helium gas discharged from the high-stage compressor (8) is adiabatically expanded to lower the temperature of the heat stations (37), (38), and the JT refrigerator (51). ) Later described precooler (5
6) and (57) are pre-cooled, and the expanded intermediate pressure helium gas is returned to the compressor (8) for recompression.

On the other hand, the shield refrigerator (40) is of the gas pressure drive type having the same structure as the pre-cooling refrigerator (26), and the motor head (4) is arranged outside the vacuum dewar (D).
1) and a cylinder (42) connected to the motor head (41) and penetrating the side wall of the vacuum dewar (D) and extending inside thereof. A high-pressure gas inlet (44) and a low-pressure gas outlet (45) are opened in the motor head (41), and the high-pressure gas inlet (44) passes through the shield-side branch high-pressure pipe (32) to the collective high-pressure pipe (33). That is, the high pressure gas discharge port (10) for the refrigerator of the compressor unit (1)
Further, the low pressure gas outlet (45) is connected to the collective intermediate pressure pipe (36), that is, the intermediate pressure gas intake port (6) of the compressor unit (1) via the shield side branch intermediate pressure pipe (35). Has been done. On the other hand, the front end of the cylinder (42) is formed in a heat station (43) which is cooled and held at a predetermined temperature level, and this heat station (43) faces the inside of the liquid nitrogen tank (Tn). Then, the shield refrigerator (40) adiabatically expands the high-pressure helium gas discharged from the high-stage compressor (8) to lower the temperature of the heat station (43) and evaporate the liquid nitrogen tank (Tn). The nitrogen gas is cooled and liquefied, and the expanded intermediate pressure helium gas is returned to the compressor (8) for recompression.

The JT refrigerator (51) is a refrigerator that expands helium gas by Joule-Thomson in order to generate cold of about 4K, and the refrigerator (51) is in the vacuum dewar (D). A first JT heat exchanger (52) arranged outside the heat shield plate (S), and second and third JT heat exchangers (53), (54) arranged inside the heat shield plate (S). Is equipped with. Each of the JT heat exchangers (52) to (54) exchanges heat between the helium gases passing through the primary side and the secondary side, respectively, and the primary side of the first JT heat exchanger (52) is compressed. It is connected to the JT high-pressure gas discharge port (12) of the machine unit (1) through a JT-side high-pressure pipe (55). In addition, the primary sides of the first and second JT heat exchangers (52) and (53) are
It is connected via a first precooler (56) arranged on the outer periphery of the first heat station (37) of the cylinder (28) in the precooling refrigerator (26). Similarly, the respective primary sides of the second and third JT heat exchangers (53), (54) are connected to each other via the second precooler (57) arranged on the outer periphery of the second heat station (38). There is. Further, the primary side of the third JT heat exchanger (54) is connected to a JT valve (58) for expanding Joule-Thomson of high pressure helium gas via an adsorber (59). The JT valve (58) is provided with an operating rod (5) from the outside of the vacuum dewar (D).
The opening is adjusted by 8a). This JT valve (58)
Are communicated with the liquid helium tank (Th) through a liquid helium return pipe (60). The inside of the helium tank (Th) is connected to the secondary side of the third JT heat exchanger (54) through a helium gas suction pipe (61). The secondary side of the third JT heat exchanger (54) is connected to the secondary side of the first JT heat exchanger (52) via the secondary side of the second JT heat exchanger (53),
The secondary side of the first JT heat exchanger (52) has a low pressure pipe (6
It is connected via 2) to the low pressure gas inlet (2) of the compressor unit (1).

That is, the JT refrigerator (51) is a refrigerant connected in series to both compressors (5) and (8) of the compressor unit (1) via high and low pressure pipes (55) and (62). A circuit is formed, and a part of the refrigerant circuit is opened to the helium tank (Th) through the liquid helium return pipe (60) and the helium gas suction pipe (61), and the refrigerant is evaporated in the helium tank (Th). The helium gas is sucked into the refrigerant circuit from the gas suction pipe (61) and the third to first JT
Suction compression is performed on the low-stage and high-stage compressors (5) and (8) of the compressor unit (1) through the respective secondary sides of the heat exchangers (54) to (52). Further, the high-pressure helium gas compressed by the high-stage compressor (8) is supplied to the first to third JT heat exchangers (5
In 2) to (54), heat is exchanged with the low temperature and low pressure helium gas toward the compressor unit (1) side, and
The first and second precoolers (56) and (57) respectively include the first and second heat stations (3) of the precooling refrigerator (26).
After cooling (pre-cooling) with 7) and (38), JT valve (58)
The Joule-Thomson expands to form liquid helium of about 4K, and this liquid helium is returned to the tank (Th) via the liquid helium return pipe (60).

The low-stage and high-stage compressors (5), (8)
And the valve motors of the pre-cooling refrigerator (26) and the shield refrigerator (40), and the first and second on-off valves (AV1) and (AV2) of the JT high-pressure adjusting mechanism (13).
1) and is controlled in operation by a control signal from the control device (71). At least a detection signal of a buffer tank pressure sensor (74) for detecting the pressure in the helium gas supply / discharge pipe (15) (internal pressure of the buffer tank (Tb)) is input to the control device (71). The internal pressure of the buffer tank (Tb) changes according to the refrigerating load of the JT refrigerator (51). When the tank pressure decreases, the refrigerating load decreases, while when the tank pressure increases, the refrigerating load increases. To do. Therefore, the buffer tank pressure sensor (74) that detects the internal pressure of the buffer tank (Tb) constitutes JT refrigerator load detection means that detects the refrigeration load of the JT refrigerator (51).

As one of the features of the present invention, a valve motor frequency controller as a displacer driving frequency varying means for controlling the rotational speed of the rotary valve driving valve motor of the precooling refrigerator (26) and the shield refrigerator (40). A valve motor frequency controller (72) is provided, and the valve motor frequency controller (72) is controlled by the control device (71).
Thus, the drive frequency of the reciprocating motion of each displacer of the precooling and shield refrigerators (26) and (40) is variable.

Then, in the control device (71), depending on the internal pressure of the buffer tank (Tb), each refrigerator (2
6) and (40), the displacer drive frequency, the operating frequency of the high-stage compressor (8), and the JT high pressure by the JT high pressure adjusting mechanism (13) are changed, and the buffer tank (T
When the internal pressure in b) falls below the set value (when the refrigeration load of the JT refrigerator (51) falls below the set value),
The displacer drive frequency of the pre-cooling refrigerator (26) is decreased and the displacer drive frequency of the shield refrigerator (40) is increased, and the pre-cooling and shield refrigerator (26),
The operating frequency of the high-stage compressor (8) that supplies high-pressure helium gas to (40) is lowered, and the first on-off valve (AV1) of the JT high-pressure adjusting mechanism (13) is opened and the second on-off valve (AV2) is opened. Is closed to lower the JT high pressure to the JT valve (58), while the internal pressure of the buffer tank (Tb) rises above the set value (when the JT load rises above the set value), conversely, The displacer drive frequency of the pre-cooling refrigerator (26) is increased and the displacer drive frequency of the shield refrigerator (40) is decreased to increase the high-stage compressor (8).
Of the JT high pressure adjustment mechanism (1
3) The first open / close valve (AV1) is closed and the second open / close valve (A1) is opened.
V2) is opened to increase the JT high pressure to the JT valve (58).

Next, the operation of the above embodiment will be described. In a steady state in which the superconducting magnet (M) operates, the superconducting coil is cooled and maintained below the critical temperature by liquid helium in the helium tank (Th). Further, the helium gas evaporated in the helium tank (Th) is a helium gas suction pipe (61) opening in the tank (Th).
Is sucked in and supplied to the refrigerant circuit of the cryogenic refrigeration system (R), where it is cooled and liquefied by compression and expansion. This liquid helium is liquid helium return pipe (60)
And then returned to the tank (Th). As a result, the liquid helium is stored in the tank (Th) in a predetermined amount or more, and the superconducting coil is stably cooled to the critical temperature or lower.

On the other hand, the liquid nitrogen in the liquid nitrogen tank (Tn) passes through the nitrogen pipe (22) and the shield plate heat exchanger (2).
3), the heat shield plate (S) is cooled and held at about 80 K by the shield plate heat exchanger (23), and by this cooling, the liquid helium tank (Th) in the heat shield plate (S) and its The internal superconducting magnet (M), the heat stations (37), (38) of the pre-cooling refrigerator (26), etc. are heat shielded from the outside. Further, liquid nitrogen is evaporated into nitrogen gas by heat exchange with the heat shield plate (S) in the shield plate heat exchanger (23), and the nitrogen gas is passed through the nitrogen pipe (22) to the liquid nitrogen tank (Tn). Return to the upper part.

The operation of the refrigeration system (R) will be described in more detail. A part of the high-pressure helium gas supplied from the high-stage compressor (8) of the compressor unit (1) is stored in the pre-cooling refrigerator (26). It expands in each expansion space in the cylinder (28), and a first temperature drop occurs due to the expansion of this gas.
The heat station (37) is cooled to a predetermined temperature level, and the second heat station (38) is cooled to a temperature level lower than that of the first heat station (37). The helium gas expanded in the expansion space returns to the compressor unit (1), is sucked into the high-stage compressor (8) through the intermediate pressure pipe (7), and is compressed.

The remaining part of the high-pressure helium gas supplied from the high-stage compressor (8) of the compressor unit (1) is part of the cylinder (4) in the shield refrigerator (40).
The heat station (43) in the liquid nitrogen tank (Tn) is cooled to a predetermined temperature level by expanding in the expansion space in 2) and the temperature drop accompanying the expansion of this gas. As a result, the nitrogen gas in the upper part of the liquid nitrogen tank (Tn) is cooled and liquefied, and returns to liquid nitrogen. The helium gas expanded in the expansion space in the cylinder (42) of the shield refrigerator (40) also returns to the compressor unit (1) in the same manner as the gas of the pre-cooling refrigerator (26), and its intermediate pressure pipe. It is sucked into the high-stage compressor (8) via (7) and compressed.

On the other hand, JT in the compressor unit (1)
High pressure piping (11) for both branch piping (11a), (11
b) the first and second on-off valves (AV1), (AV
Any one of 2) is opened, and the rest of the high-pressure helium gas discharged from the high-stage compressor (8) passes through the JT high-pressure pipe (11) to the first JT of the JT refrigerator (51). It enters into the primary side of the heat exchanger (52), where it is heat-exchanged with the low-pressure helium gas on the secondary side toward the compressor unit (1) side, cooled from room temperature 300K to, for example, about 50K, and then the above pre-cooling refrigeration. The first precooler (56) around the outer periphery of the first heat station (37) of the machine (26) is further cooled. This cooled gas is transferred to the second JT heat exchanger (5
After entering the primary side of 3) and being cooled to, for example, about 15K by heat exchange with low pressure helium gas on the secondary side as well,
Second heat station (38) of the pre-cooling refrigerator (26)
It enters the second precooler (57) on the outer periphery and is further cooled.
Thereafter, the gas enters the primary side of the third JT heat exchanger (54) and is further cooled by heat exchange with the low pressure helium gas on the secondary side, and then reaches the JT valve (58). This JT
At the valve (58), the high-pressure helium gas is squeezed and expanded by Joule-Thomson to become liquid helium of about 4K, and this liquid helium is supplied to the liquid helium tank (Th) via the liquid helium return pipe (60). It Further, the helium gas evaporated in the liquid helium tank (Th) is passed through the helium gas suction pipe (61) to the third JT.
The second and first J are sucked into the secondary side of the heat exchanger (54).
It is sucked into the low-stage compressor (5) via the secondary sides of the T heat exchangers (53), (52) and compressed.

Then, such a cryogenic refrigerator (R)
During operation, the pressure inside the buffer tank (Tb) is detected as a refrigerating load of the JT refrigerator (51) by the buffer tank pressure sensor (74), and the control device receives a signal from the buffer tank pressure sensor (74). According to (71)
The JT high pressure by the displacer driving frequency of each of the refrigerators (26) and (40), the operating frequency of the high-stage compressor (8), and the open / close valves (AV1) and (AV2) of the JT high pressure adjusting mechanism (13) is buffered. It is controlled according to the internal pressure of the tank (Tb). That is, when the internal pressure of the buffer tank (Tb) drops below the set value and the JT load drops,
The displacer drive frequency of the pre-cooling refrigerator (26) decreases and the displacer drive frequency of the shield refrigerator (40) increases, the operating frequency of the high-stage compressor (8) decreases, and the JT high-pressure adjusting mechanism (13) ), The first on-off valve (AV1) is opened and the second on-off valve (AV2) is closed to reduce the JT high pressure to the JT valve (58). This reduces the refrigerating capacity of the JT refrigerator (51).

On the other hand, when the internal pressure of the buffer tank (Tb) rises above the set value (when the refrigeration load of the JT refrigerator (51) rises), the displacer drive frequency of the precooling refrigerator (26) rises. Shikatsu Shield Refrigerator (4
0) the displacer drive frequency is decreased, the operating frequency of the high-stage compressor (8) is increased, and the first on-off valve (AV1) of the JT high-pressure adjusting mechanism (13) is closed and the second on-off valve (AV2) is closed. ) Is opened to increase the JT high pressure to the JT valve (58), and the refrigerating capacity of the JT refrigerator (51) is increased as described above.

Therefore, in this embodiment, the displacer drive frequencies of the pre-cooling refrigerator (26) and the shield refrigerator (40) of the JT refrigerator (51) in the cryogenic refrigerator (R) are variable, and both of them are variable. Refrigerator (26),
The refrigerating capacity of (40) can be changed independently, and even when the pre-cooling refrigerator (26) and the shield refrigerator (40) are multi-operated, refrigeration of the pre-cooling refrigerator (26), that is, the JT refrigerator (51). The capacity distribution between the capacity and the refrigerating capacity of the shield refrigerator (40) can be adjusted by using the refrigerators having the same specifications, and various refrigeration can be performed without changing the specifications of the refrigerators (26) and (40). It is possible to meet the demand for ability. Incidentally, FIG. 2 exemplifies changes in the refrigerating capacity of the precooling and shield refrigerators (26) and (40) when the displacer drive frequency of the precooling refrigerator (26) is changed. The refrigerating capacity of the pre-cooling refrigerator (26) increases and the refrigerating capacity of the shield refrigerator (40) decreases in accordance with the increase in the displacer driving frequency.

Further, the internal pressure of the buffer tank (Tb) (J
According to the refrigerator load of the T refrigerator (51), each refrigerator (2
Since the displacer drive frequency of 6) and (40) is changed, even if the internal pressure of the buffer tank (Tb) changes and the load of the JT refrigerator (51) changes during the multi-operation of the cryogenic refrigerator (R), The refrigerating capacities of the two refrigerators (26) and (40) do not change uniformly in the same manner, and the refrigerating capacity can be changed according to the load. It is also possible to change the refrigerating capacity of the JT refrigerator (51) while keeping it constant, so that a wide range of capacity control of the JT refrigerator (51) can be performed.

The operating frequency of the high-stage compressor (8) of the compressor unit (1) is variable independently of the low-stage compressor (5), and the operating frequency of the high-stage compressor (8) is Since it can be changed according to the internal pressure of the buffer tank (Tb) (refrigeration load of the JT refrigerator (51)), the refrigerators (26), (4
It is possible to change not only the displacer drive frequency of 0) but also the operating frequency of the high-stage compressor (8) according to the load of the JT refrigerator (51), and the JT refrigerator during multi-operation of the refrigerator (R). The refrigerating capacity can be largely changed according to the change in the load of (51), and a wider range of capacity control of the JT refrigerator (51) can be performed. FIG. 3 shows the performance characteristics of the pre-cooling and shield refrigerators (26), (40) shown in FIG. 2 in which the operating frequency of the high-stage compressor (8) is increased, and only the increase in the operating frequency is shown. The refrigerating capacity of both the precooling and shield refrigerators (26) and (40) is increasing.

Further, the JT high pressure adjusting mechanism (13) is controlled according to the internal pressure of the buffer tank (Tb) (refrigerating load of the JT refrigerator (51)) to adjust the pressure of helium gas to the JT valve (58). Therefore, JT refrigerator (5
The refrigerating capacity can be largely changed according to the change in the load of 1), and a wider range of capacity control of the JT refrigerator (51) can be performed.

In the above embodiment, when the internal pressure of the buffer tank (Tb) drops below the set value, the displacer driving frequency of the pre-cooling refrigerator (26) is lowered and the displacer driving of the shield refrigerator (40) is driven. While increasing the frequency, when the internal pressure of the buffer tank (Tb) rises above the set value, the displacer drive frequency of the precooling refrigerator (26) is increased and the shield refrigerator (4)
The displacer drive frequency of 0) is reduced, but when the internal pressure of the buffer tank (Tb) decreases,
At least one of decreasing the displacer driving frequency of the precooling refrigerator (26) and increasing the displacer driving frequency of the shield refrigerator (40) is performed, and the buffer tank (T
At the time of increasing the internal pressure in b), at least one of increasing the displacer driving frequency of the precooling refrigerator (26) and decreasing the displacer driving frequency of the shield refrigerator (40) may be performed.

Further, in the above embodiment, the refrigerators (26), (40) are set in accordance with the internal pressure of the buffer tank (Tb).
Displacer drive frequency, high-stage compressor (8) operating frequency, and JT high-pressure adjusting mechanism (13) on-off valve (A
Although the JT high voltage is controlled by V1) and (AV2), only the displacer drive frequency of the refrigerators (26) and (40) may be variably controlled. However, in the point that the refrigerating capacity of the JT refrigerator (51) can be widened, the refrigerator (26),
In addition to the control of the displacer drive frequency of (40), it is preferable to variably control the operating frequency of the high-stage compressor (8) and the JT high pressure by the JT high pressure adjusting mechanism (13).

Furthermore, the pre-cooling and shield refrigerator (2
The helium gas pressure to the displacer of each refrigerator (26), (40) may be changed by adjusting the opening degree of the variable orifice incorporated in each of (6), (40). That is, in the control device (71), the opening of the variable orifice is controlled according to the change of the displacer driving frequency, and as shown in FIG. 4, the orifice opening is controlled to increase as the driving frequency increases. By doing this, the pre-cooling and shield refrigerator (26),
Not only the displacer drive frequency of (40), but also the helium gas pressure to the displacer is controlled to the optimum aperture according to the change of the displacer drive frequency of each refrigerator (26), (40). Therefore, the capacity distribution between the refrigerating capacity of the pre-cooling refrigerator (26) and the refrigerating capacity of the shield refrigerator (40) can be adjusted over a wider range to meet a large demand for refrigerating capacity.

Further, in the above embodiment, the refrigerators (26), (40) are set in accordance with the internal pressure of the buffer tank (Tb).
Displacer drive frequency, high-stage compressor (8) operating frequency, and JT high-pressure adjusting mechanism (13) on-off valve (A
Although the JT high pressure by V1) and (AV2) is controlled, the operating frequency of the low-stage compressor (5) is made variable, and the operating frequency of this compressor (5) together with the JT high pressure is in the buffer tank (Tb). Control device according to the internal pressure of (71)
The operating frequency of the compressor (5) is reduced when the internal pressure of the buffer tank (Tb) (refrigerating load of the JT refrigerator (51)) falls below a set value, while the operating frequency of the compressor (5) is reduced. It is also possible to raise when the internal pressure exceeds the set value. With this configuration, when the internal pressure of the buffer tank (Tb) decreases and the refrigerating load of the JT refrigerator (51) decreases below the set value, the operating frequency of the low-stage compressor (5) decreases and the JT refrigerator (51) decreases. When the refrigeration capacity of the JT refrigerator (51) increases more than the set value by increasing the internal pressure of the buffer tank (Tb) while the refrigerating capacity of) decreases, the operating frequency of the compressor (5) increases,
The refrigerating capacity of the JT refrigerator (51) will increase,
A wider range of capacity control of the JT refrigerator (51) can be performed by greatly changing the refrigerating capacity according to the change in the load of the JT refrigerator (51).

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
In the following embodiments, the same parts as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof will be omitted). Shield refrigerator (26), (40)
While the displacer drive frequency is controlled variably, the flow rate of helium gas to the refrigerators (26) and (40) is controlled variably.

That is, in this embodiment, the precooling-side branch high-pressure pipe (31) for supplying the high-pressure helium gas of the compressor unit (1) to the pre-cooling refrigerator (26) is composed of a solenoid valve whose opening can be adjusted. The pre-cooling side flow rate adjustment valve (AV3)
Further, similar shield side flow rate adjusting valves (AV4) are arranged in the middle of the shield side branch high pressure piping (32) for supplying the high pressure helium gas to the shield refrigerator (40), and these flow rate adjusting valves (AV3 ), (AV4) constitutes a helium flow rate adjusting mechanism (46) for adjusting the flow rate of helium gas to the two refrigerators (26), (40).

Then, the both flow rate adjusting valves (AV3),
The control device (71) controls the operation of (AV4), and the control device (71) controls the high stage according to the internal pressure of the buffer tank (Tb) (refrigeration load of the JT refrigerator (51)). Compressor (8) and JT high pressure adjusting mechanism (13)
In addition to controlling the operation in the same manner as in the first embodiment, the openings of the precooling side and shield side flow rate adjusting valves (AV3) and (AV4) are controlled to control the helium gas for the refrigerators (26) and (40). When the flow rate is changed and the internal pressure of the buffer tank (Tb) falls below the set value and the refrigeration load of the JT refrigerator (51) decreases, the flow rate of helium gas to the pre-cooling refrigerator (26) decreases while the buffer flow decreases. Tank (T
The internal pressure of b) rises above the set value and the JT refrigerator (51)
When the refrigeration load of the shield refrigerator (4
The helium gas flow rate with respect to 0) is reduced. Other configurations are the same as those of the first embodiment.

Therefore, in this embodiment, according to the internal pressure of the buffer tank (Tb) (refrigerating load of the JT refrigerator (51)), the precooling side and shield side flow rate adjusting valves (AV
3) and (AV4) are controlled to adjust the helium gas flow rates to the precooling and shield refrigerators (26) and (40), and the operating frequency of the high-stage compressor (8) and the JT high pressure adjusting mechanism. (13) is controlled, and when the internal pressure of the buffer tank (Tb) falls below the set value and the refrigeration load of the JT refrigerator (51) decreases, the pre-cooling refrigerator (2
The openings of both flow rate adjusting valves (AV3) and (AV4) are controlled so that the flow rate of helium gas with respect to 6) decreases. Also, the operating frequency of the high-stage compressor (8) is lowered, and the helium gas pressure to the JT valve (58) is further lowered to the JT.
The high pressure adjusting mechanism (13) is adjusted. This reduces the refrigerating capacity of the JT refrigerator (51).

On the other hand, when the internal pressure of the buffer tank (Tb) rises above the set value and the refrigerating load of the JT refrigerator (51) increases, the flow rate of helium gas to the shield refrigerator (40) is decreased so that both flow rates decrease. Flow control valve (AV
3), the opening of (AV4) is controlled, at the same time, the operating frequency of the high-stage compressor (8) rises, and the helium gas pressure to the JT valve (58) rises so that the JT high-pressure adjusting mechanism (13).
Is adjusted, which increases the refrigerating capacity of the shield refrigerator (40). Therefore, also in this embodiment, the same operational effects as those of the first embodiment can be obtained.

FIG. 6 shows changes in the refrigerating capacity of the precooling and shield refrigerators (26) and (40) when the opening degree of the precooling side flow rate adjusting valve (AV3) corresponding to the precooling refrigerator (26) is changed. Is an example of the flow control valve on the pre-cooling side (AV3)
As the helium gas flow rate to the pre-cooling refrigerator (26) increases by increasing the opening degree of, the refrigerating capacity of the pre-cooling refrigerator (26) increases and the refrigerating capacity of the shield refrigerator (40) decreases. ing. Then, as shown in FIG. 7, in the performance characteristics of the precooling and shield refrigerators (26) and (40) shown in FIG. 6, when the operating frequency of the high-stage compressor (8) is increased, The refrigerating capacities of both the precooling and shield refrigerators (26) and (40) increase by the amount of increase.

In the second embodiment, the precooling side and shield side flow rate adjusting valves (AV3), (A) are provided in the middle of the precooling side and shield side branch high-pressure pipes (31), (32), respectively.
V4) is arranged to adjust the flow rate of helium gas to the two refrigerators (26) and (40), but the pre-cooling side branch intermediate pressure pipe (34) and the shield side branch intermediate pressure pipe. A similar flow rate adjusting valve may be arranged in the middle of (35). Further, as in the above embodiment, the flow rate adjusting valves (AV3), (A
Instead of providing V4), a combination of a throttle valve having a constant throttle opening and an on-off valve consisting of a solenoid valve that is in a fully closed or fully open state is provided in each pipe (31), (32) (or (34). ，
(35)) can be connected in parallel, and the gas flow rate can be adjusted by controlling the opening / closing of each of the on-off valves. The point is that the flow rate of helium gas to both refrigerators (26) and (40) can be adjusted.

Also in this second embodiment, the operating frequency of the low-stage compressor (5) is variably controlled according to the internal pressure of the buffer tank (Tb) (refrigerating load of the JT refrigerator (51)), and this compression is performed. The operating frequency of the machine (5) may be lowered when the internal pressure of the buffer tank (Tb) is decreased, and may be increased when the internal pressure of the buffer tank (Tb) is increased. The refrigerating capacity can be largely changed according to the change of the load, and a wider range of capacity control of the JT refrigerator (51) can be performed.

(Third Embodiment) FIG. 8 shows a third embodiment.
In the first embodiment, the low-stage and high-stage compressors (5), (8)
Are connected in series to precool and shield the high-pressure helium gas discharged from the high-stage compressor (8) (26), (4
0) and the JT valve (58) are supplied to the compressor unit (1) in the first embodiment.
The structure of the precooling and shield refrigerator (26), (4
0) and the JT refrigerator (51) are independent compressors.

In this embodiment, the compressor unit (1)
Are independently provided with compressors (18) and (19) for refrigerators and JTs, each of which is operated and controlled by the control device (71), and the discharge side of the compressor (18) for refrigerators has a high-pressure pipe ( Three
3), (31) and (32) through the high pressure gas inlets (29) of the precooling and shield refrigerators (26) and (40),
(44) and low pressure piping (36 '), (3
4 ') and (35') through both refrigerators (26), (4
0) low pressure gas outlets (30) and (45) respectively, and one refrigerator compressor (18) to two precooling and shield refrigerators (26) and (40) high pressure helium. I am trying to supply gas.

On the other hand, the discharge side of the JT compressor (19) is connected to the first JT heat exchanger (52) through the high pressure pipe (55).
To the next side and the suction side through the low pressure pipe (62)
High pressure helium gas is supplied to the secondary side of the T heat exchanger (52), and the JT compressor (19) supplies high pressure helium gas to the JT valve (58) of the JT refrigerator (51).

Then, the pre-cooling and shield refrigerator (2
The operating frequency of the compressor (18) for the refrigerator that supplies high-pressure helium gas to 6) and (40) is variable independently of the compressor (19) for the JT, and in the control device (71), Internal pressure of the buffer tank (Tb) (JT refrigerator (5
When the refrigeration load (1)) is lower than the set value, the operating frequency of the compressor (18) for a refrigerator for supplying high-pressure helium gas to the precooling and shield refrigerators (26), (40) is lowered, When the internal pressure of the buffer tank (Tb) increases and the refrigerating load of the JT refrigerator (51) increases above a set value, the operating frequency of the refrigerator compressor (18) is increased. There is. Others are the same as those in the first embodiment. Therefore, in this embodiment, it is possible to obtain the same effect as that of the first embodiment.

Also in the third embodiment, the operating frequency of the JT compressor (19) is variably controlled according to the internal pressure of the buffer tank (Tb) (refrigerating load of the JT refrigerator (51)), and this compression is performed. If the operating frequency of the machine (19) is lowered when the internal pressure of the buffer tank (Tb) is lowered, while it is raised when the internal pressure of the buffer tank (Tb) is increased, the refrigeration of the JT refrigerator (51) is reduced. The capacity can be largely changed according to the change of the load, and a wider range of capacity control of the JT refrigerator (51) can be performed.

(Fourth Embodiment) FIG. 9 shows a fourth embodiment.
As in the second embodiment, the pre-cooling and shield refrigerator (2
6), (40) helium gas flow rate to the internal pressure of the buffer tank (Tb) (refrigerating load of the JT refrigerator (51))
In the configuration in which the variable control is performed in accordance with the above, the precooling and shield refrigerators (26), (4
Compressor for refrigerator (18) which supplies helium gas to 0)
And a JT compressor (19) for supplying helium gas to the JT valve (58) of the JT refrigerator (51). Also in this embodiment, the same operational effect as that of the second embodiment can be obtained.

(Fifth Embodiment) FIG. 10 shows a fifth embodiment. In the first embodiment, the precooling and shield refrigerator (2
The drive frequencies of the displacers 6) and 40) are controlled according to the internal pressure of the buffer tank (Tb), that is, the refrigeration load of the JT refrigerator (51), whereas the refrigeration of the shield refrigerator (40) is controlled. The control is variably controlled according to the load.

That is, in this embodiment, a nitrogen tank pressure sensor (76) as a shield refrigerator load detecting means for detecting the pressure in the liquid nitrogen tank (Tn) is provided in the nitrogen pipe (22) on the atmosphere release valve side. The refrigerating load of the shield refrigerator (40) is detected by the internal pressure of the nitrogen tank (Tn) detected by the sensor (76). )
The cooling temperature of the heat station (43) may be directly detected as the refrigeration load).

The nitrogen tank pressure sensor (76)
Is connected to the control device (71), and the control unit (73) of the control device (71) controls the valve motor frequency controller (72) to set the detected internal pressure of the nitrogen tank (Tn). When the refrigeration load of the shield refrigerator (40) decreases below the value, the pre-cooling refrigerator (2
While the displacer drive frequency of 6) or the displacer drive frequency of the shield refrigerator (40) is increased (or one of them), the internal pressure of the nitrogen tank (Tn) rises above the set value and the shield refrigerator ( When the refrigerating load of 40) increases, both (or one) of the displacer driving frequency of the pre-cooling refrigerator (26) and the displacer driving frequency of the shield refrigerator (40) increase.

Further, the control device (71) is the same as that of the first embodiment.
Similarly, the operating frequency of the high-stage compressor (8) is also controlled, and when the internal pressure of the nitrogen tank (Tn) (refrigeration load of the shield refrigerator (40)) drops below a set value, precooling and shield refrigeration are performed. While lowering the operating frequency of the high-stage compressor (8) that supplies high-pressure helium gas to the machines (26) and (40), when the internal pressure of the above-mentioned nitrogen tank (Tn) rises above a set value, The operating frequency of the compressor (8) is increased.

In the case of this embodiment, a nitrogen tank (Tn)
Internal pressure (refrigeration load of the shield refrigerator (40)) is detected by the nitrogen tank pressure sensor (76), and the precooling and shield refrigerator (2) are detected according to the internal pressure of the nitrogen tank (Tn).
6) When the driving frequency of the displacer of (40) is changed and the internal pressure of the nitrogen tank (Tn) is lowered and the refrigerating load of the shield refrigerator (40) is lower than the set value, the displacer of the precooling refrigerator (26) is reduced. The drive frequency increases and the displacer drive frequency of the shield refrigerator (40) decreases, which causes the shield refrigerator (40).
The refrigeration capacity of is reduced.

On the other hand, when the internal pressure of the nitrogen tank (Tn) rises and the refrigerating load of the shield refrigerator (40) exceeds the set value, the displacer drive frequency of the precooler (26) decreases and the shield refrigerating machine (40) operates. The displacer drive frequency of the machine (40) increases and the shield refrigerator (40)
The refrigeration capacity of can be increased. Therefore, even if the refrigerating load of the shield refrigerator (40) changes during the multi-operation of the cryogenic refrigerator (R), the refrigerating capacity of the shield refrigerator (40) can be changed according to the load. While keeping the refrigerating capacity of the refrigerator (51) substantially constant, the refrigerating capacity of the shield refrigerator (40) can be changed, and a wide range of capacity control of the shield refrigerator (40) can be performed.

The operating frequency of the high-stage compressor (8) is changed according to the internal pressure of the nitrogen tank (Tn) (refrigerating load of the shield refrigerator (40)), and the shield refrigerator (4
The operating frequency of the high-stage compressor (8) decreases when the refrigeration load falls below the set value of 0), and the operating frequency of the high-stage compressor (8) falls when the refrigerating load rises above the set value. Therefore, the refrigerating capacity can be largely changed according to the change of the load of the shield refrigerator (40) during the multi-operation of the cryogenic refrigerator (R), and the capacity control of the shield refrigerator (40) is wider. It can be performed.

(Sixth Embodiment) FIG. 11 shows a sixth embodiment, in which, as in the case of the above-mentioned second embodiment, both the refrigerating and chilling refrigerators (26) and (40) are variably controlled in the flow rate of the helium gas. The displacer drive frequency of the machines (26) and (40) is variably controlled according to the refrigerating load of the shield refrigerator (40).

In this embodiment, in the configuration of the second embodiment, the output signal of the nitrogen tank pressure sensor (76) similar to that of the fifth embodiment is input to the control device (71),
Depending on the internal pressure of the nitrogen tank (Tn) detected by the nitrogen tank pressure sensor (76) (refrigeration load of the shield refrigerator (40)), the flow rate of helium gas to the refrigerators (26) and (40) is changed. When the internal pressure of the nitrogen tank (Tn) is variably controlled and the refrigerating load of the shield refrigerator (40) is lower than the set value, the helium gas flow rate to the shield refrigerator (40) is decreased and the nitrogen flow rate is decreased. Tank (T
When the internal pressure of n) rises and the refrigerating load of the shield refrigerator (40) exceeds the set value, the precooling refrigerator (26).
The helium flow rate adjusting mechanism (46) is controlled so that the helium gas flow rate with respect to the. The other configurations are the same as those in the sixth embodiment. Therefore, also in this embodiment, the same operational effect as that of the sixth embodiment can be obtained.

[0101]

As described above, according to the invention of claim 1, in the cryogenic refrigeration system provided with at least one compressor and a plurality of refrigerators connected in parallel to the compressor, The driving frequency of the reciprocating motion of the displacer of at least one refrigerator is variable. Claim 7
In the invention, the flow rate of the refrigerant gas to at least one refrigerator is adjusted in the cryogenic refrigeration system on the same premise as described above. Therefore, according to these inventions,
The refrigerating capacity can be changed by changing the displacer drive frequency or the refrigerant gas flow rate of at least one of the plurality of units, and the capacity distribution of the refrigerators must be changed to change the capacity of each refrigerator. Instead, a wide range of adjustments can be made according to the refrigerating capacity.

According to the invention of claim 2 or 8, the plurality of refrigerators are the pre-cooling refrigerator in the JT refrigerator and the JT refrigerator.
By using a shield refrigerator that shields the cryogenic cooling portion of the refrigerator from heat, each of the JT refrigerator and the shield refrigerator can be operated when the pre-cooling refrigerator and the shield refrigerator of the JT refrigerator are multi-operated. Adjust the capacity distribution of the refrigerating capacity without changing the specifications of each refrigerator,
It is possible to meet various refrigerating capacity requirements.

In the invention of claim 3 or 9, the compressors are low-stage and high-stage compressors connected in series, and the precooling and shield refrigerator expands the refrigerant gas discharged from the high-stage compressor. It is supposed to be configured. Further, in the invention of claim 4 or 10, the compressor is composed of a compressor for a refrigerator that supplies a refrigerant gas to the pre-cooling and shield refrigerator and a compressor for a JT that supplies the refrigerant gas to a JT valve. According to these inventions, the connection structure of the compressor to the precooling and shield refrigerator can be realized.

In the invention of claim 5 or 11, the operating frequencies of the low-stage and high-stage compressors are independently variable. Further, in the invention of claim 6 or 12, the operating frequencies of the compressor for the refrigerator and the compressor for the JT are independently variable. According to these inventions, by changing not only the displacer drive frequency of the refrigerator but also the operating frequency of the compressor, the capacity distribution between the refrigerating capacity of the pre-cooling refrigerator and the refrigerating capacity of the shield refrigerator can be spread over a wider range. It can be adjusted to meet significant refrigeration requirements.

According to the thirteenth aspect of the present invention, in the first aspect of the present invention, each refrigerator is a gas pressure drive type refrigerator provided with a variable orifice for changing the refrigerant gas pressure for the displacer to adjust the drive frequency thereof. By changing the opening of the variable orifice according to the change of the displacer drive frequency, the displacer drive frequency of the refrigerator and the refrigerant gas pressure for the displacer are also changed, and the refrigerating capacity and shield refrigeration of the pre-cooling refrigerator are changed. The capacity distribution with the refrigerating capacity of the machine can be adjusted over a wider range to meet a large demand for refrigerating capacity.

According to a fourteenth aspect of the present invention, the refrigerating load of the JT refrigerator is detected, and when the refrigerating load of the JT refrigerator is lower than a set value, the displacer drive frequency of the precooling refrigerator is reduced or the shield refrigeration is performed. When at least one of the displacer drive frequency of the refrigerator is increased, and when the refrigeration load of the JT refrigerator exceeds the set value, the displacer drive frequency of the pre-cooler refrigerator or the displacer drive frequency of the shield refrigerator is decreased. I tried to do at least one. In the invention of claim 18, the JT
When the refrigerating load of the refrigerator is lower than the set value, the flow rate of the refrigerant gas to the pre-cooling refrigerator is reduced, and J
When the refrigerating load of the T refrigerator exceeds the set value, the refrigerant gas flow rate to the shield refrigerator is reduced. Therefore, according to these inventions, even if the load of the JT refrigerator changes during the multi-operation of the cryogenic refrigerator, the refrigerating capacity can be changed according to the load, and the refrigerating capacity of the shield refrigerator is substantially constant. It is possible to change the refrigerating capacity of the JT refrigerator while maintaining the above, and it is possible to perform a wide range of capacity control of the JT refrigerator.

According to the invention of claim 15 or 19, in the invention of claim 14 or 18, the operating frequency of the compressor corresponding to the precooling and shield refrigerator is made variable, and the refrigerating load of the JT refrigerator is higher than the set value. When the temperature decreases, the operating frequency of the compressor that supplies the high-pressure refrigerant gas to the pre-cooling and shield refrigerator is decreased, while the operating frequency of the compressor is increased when the refrigeration load of the JT refrigerator exceeds the set value. By doing so, not only the displacer drive frequency of the refrigerator but also the operating frequency of the compressor can be changed according to the refrigerating load of the JT refrigerator, and the load of the JT refrigerator during multi-operation of the refrigerating machine can be changed. Accordingly, the refrigerating capacity can be greatly changed, and a wider range of capacity control of the JT refrigerator can be performed.

According to the invention of claim 16 or 20, in the invention of claim 14 (or 15) or 19, the JT
When the refrigerating load of the refrigerator drops below the set value, JT
By reducing the refrigerant gas pressure to the valve and increasing the refrigerant gas pressure to the JT valve when the refrigeration load of the JT refrigerator exceeds the set value, The refrigerating capacity can be greatly changed to perform a wider range of capacity control of the JT refrigerator.

In the invention of claim 17 or 21, claim 1
In the invention of 6 or 20, the operating frequency of the low-stage compressor or the compressor for JT is made variable, and the operating frequency of this compressor is lowered when the refrigeration load of the JT refrigerator drops below a set value, while the JT By increasing the refrigeration load of the refrigerator when it exceeds the set value, the low stage or J
By changing the operating frequency of the T compressor, the refrigerating capacity can be greatly changed in accordance with the change in the load of the JT refrigerator, and a wide range of capacity control of the JT refrigerator can be performed.

According to the twenty-second aspect of the invention, in the cryogenic refrigerator of the third or fourth aspect of the invention, the refrigerating load of the shield refrigerator is detected, and the detected refrigerating load of the shield refrigerator is lower than the set value. When the refrigeration load rises above the set value, the displacer drive frequency of the pre-cooling refrigerator is increased and / or the displacer drive frequency of the shield refrigerator is decreased. At least one of the decrease and the increase of the displacer drive frequency of the shield refrigerator is performed. Further, in the invention of claim 24, similarly to the invention of claim 9 or 10, the refrigerating load of the shield refrigerator is detected, and when the refrigerating load falls below a set value, the refrigerant gas for the shield refrigerator is Flow rate
Further, when the refrigeration load exceeds the set value, the refrigerant gas flow rate to the precooling refrigerator is reduced. Therefore, according to these inventions, even if the load of the shield refrigerator changes during the multi-operation of the cryogenic refrigerator, the refrigerating capacity is changed according to the load of the shield refrigerator,
While keeping the refrigerating capacity of the JT refrigerator substantially constant, the refrigerating capacity of the shield refrigerator can be changed, and a wide range of capacity control of the shield refrigerator can be performed.

According to the invention of claim 23 or 25, in the invention of claim 22 or 24, when the refrigerating load of the shield refrigerator is lower than a set value, a high-pressure refrigerant gas is supplied to the precooling and shield refrigerator. While reducing the operating frequency of the compressor with variable operating frequency, and increasing the operating frequency of the compressor when the refrigeration load increases above the set value, not only the displacer drive frequency of the refrigerator but also the compressor The refrigerating capacity can be largely changed according to the load change of the shield refrigerator during the multi-operation of the refrigerating apparatus by changing the operating frequency of the refrigerator, and a wider range of capacity control of the shield refrigerator can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a cryogenic refrigerator according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing changes in the refrigerating capacity of the pre-cooling and shield refrigerator according to the displacer drive frequency of the pre-cooling refrigerator.

FIG. 3 is a diagram corresponding to FIG. 2 showing changes in refrigerating capacity of the precooling and shield refrigerator when the operating frequency of the high-stage compressor is increased in the first embodiment.

FIG. 4 is a characteristic diagram showing a characteristic of an orifice opening degree according to a displacer driving frequency in the first embodiment.

FIG. 5 is a view corresponding to FIG. 1 showing a second embodiment.

FIG. 6 is a diagram corresponding to FIG. 2 showing changes in the refrigerating capacity of the precooling and shield refrigerator according to the helium gas flow rate with respect to the precooling refrigerator.

FIG. 7 is a diagram corresponding to FIG. 1 showing changes in the refrigerating capacity of the precooling and shield refrigerator when the operating frequency of the high-stage compressor is increased in the second embodiment.

FIG. 8 is a view corresponding to FIG. 1 showing a third embodiment.

FIG. 9 is a view corresponding to FIG. 1 showing a fourth embodiment.

FIG. 10 is a view corresponding to FIG. 1 showing a fifth embodiment.

FIG. 11 is a view corresponding to FIG. 1 showing a sixth embodiment.

[Explanation of symbols]

(R) Cryogenic refrigerator (1) Compressor unit (5) Low-stage compressor (8) High-stage compressor (13) JT high-pressure adjusting mechanism (JT high-pressure adjusting means) (18) Compressor for refrigerator (19) ) JT compressor (V1), (V2) Flow rate adjusting valve (AV1), (AV2) Electromagnetic on-off valve (21) Refrigerator unit (26) Pre-cooling refrigerator (37), (38) Heat station (40) Shield Refrigerator (43) Heat station (46) Helium gas flow rate adjusting mechanism (refrigerant flow rate adjusting means) (51) JT refrigerator (58) JT valve (71) Control device (control means) (72) Valve motor frequency controller ( Displacer drive frequency varying means) (74) Buffer tank pressure sensor (JT refrigerator load detecting means) (76) Nitrogen tank pressure sensor (shield refrigerator load detecting means) (T ) Buffer tank (Tb) liquid helium tank (D) vacuum dewar (Tn) a liquid nitrogen tank (S) the heat shield plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masakazu Okamoto 1304 Kanaoka-machi, Sakai City, Osaka Daikin Industry Co., Ltd.Kanaoka Plant, Sakai Manufacturing Co., Ltd. (72) Inventor Katsuya Miura, 1304 Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industries, Ltd. Kanaoka Factory, Sakai Plant

Claims (25)

[Claims] 1. At least one compressor that compresses a refrigerant gas, and a plurality of compressors that are connected in parallel to the compressor and that expand the refrigerant gas from the compressor by the reciprocating motion of a displacer to generate a cryogenic temperature. A cryogenic refrigerator comprising refrigerators (26) and (40), wherein a displacer drive frequency varying means for varying the reciprocating drive frequency of the displacer of at least one of the refrigerators (26) and (40). A cryogenic refrigerator comprising (72). 2. The cryogenic refrigerator according to claim 1, wherein the plurality of refrigerators (26), (40) are poled by Joule-Thomson expansion of the high pressure refrigerant gas from the compressor at the JT valve (58). A precooling refrigerator (26) attached to a JT refrigerator (51) that generates a low temperature and precooling the refrigerant gas before the Joule-Thomson expansion, and at least a cryogenic cooling portion by the JT refrigerator (51) from the outside. A cryogenic refrigerator comprising a shield refrigerator (40) for heat shield. 3. The cryogenic refrigeration system according to claim 2, wherein the compressor compresses a low-stage compressor (5) for compressing a refrigerant gas and a refrigerant gas discharged from the low-stage compressor (5). The pre-cooling and shield refrigerators (26) and (40) are configured to expand the refrigerant gas discharged from the high-stage compressor (8). Cryogenic refrigerator. 4. The cryogenic refrigerator according to claim 2, wherein the compressor is a precooling and shield refrigerator (26), (40).
Refrigerator compressor (18) for supplying the refrigerant gas to the JT compressor (1) and JT compressor (1) for supplying the refrigerant gas to the JT valve (58)
9) A cryogenic refrigeration system comprising: 5. The cryogenic refrigeration system according to claim 3, wherein the operating frequencies of the low-stage and high-stage compressors (5), (8) are independently variable. apparatus. 6. The cryogenic refrigeration system according to claim 4, wherein the operating frequencies of the compressors (18) and (19) for the refrigerator and the JT are independently variable. Refrigeration equipment. 7. At least one compressor for compressing a refrigerant gas, and a plurality of refrigerators (26) connected in parallel to the compressor and expanding the refrigerant gas from the compressor to generate a cryogenic temperature. , (40), a refrigerant flow rate adjusting means (46) for adjusting the flow rate of the refrigerant gas to the at least one refrigerator (26), (40).
A cryogenic refrigeration system characterized by being provided with. 8. The cryogenic refrigeration system according to claim 7, wherein the plurality of refrigerators (26), (40) are polarized by Joule-Thomson expansion of the high pressure refrigerant gas from the compressor at the JT valve (58). A precooling refrigerator (26) attached to a JT refrigerator (51) that generates a low temperature and precooling the high-pressure refrigerant gas before the Joule-Thomson expansion, and at least a cryogenic cooling portion by the JT refrigerator (51) to the outside. And a shield refrigerator (40) for heat shielding from the cryogenic refrigerator. 9. The cryogenic refrigeration system according to claim 8, wherein the compressor compresses a low-stage compressor (5) for compressing a refrigerant gas and a refrigerant gas discharged from the low-stage compressor (5). The pre-cooling and shield refrigerators (26) and (40) are configured to expand the refrigerant gas discharged from the high-stage compressor (8). Cryogenic refrigerator. 10. The cryogenic refrigerator according to claim 8, wherein the compressor is a precooling and shield refrigerator (26), (40).
Refrigerator compressor (18) for supplying the refrigerant gas to the JT compressor (1) and JT compressor (1) for supplying the refrigerant gas to the JT valve (58)
9) A cryogenic refrigeration system comprising: 11. The cryogenic refrigeration system according to claim 9, wherein the operating frequencies of the low-stage and high-stage compressors (5), (8) are independently variable. apparatus. 12. The cryogenic refrigeration system according to claim 10, wherein the operating frequencies of the compressors (18), (19) for the refrigerator and the compressor for JT are independently variable. Refrigeration equipment. 13. The cryogenic refrigerator according to claim 1, wherein each of the refrigerators (26), (40) is a gas pressure drive type refrigerator that drives a displacer at a pressure of a refrigerant gas,
Further, a variable orifice for adjusting the movement of the displacer by changing the refrigerant gas pressure to the displacer is provided, and the opening of the variable orifice is controlled according to the change of the displacer drive frequency. Low temperature refrigerator. 14. The cryogenic refrigerator according to claim 3 or 4, wherein JT refrigerator load detecting means (74) for detecting a refrigerating load of the JT refrigerator (51), and JT refrigerator load detecting means (74). When the refrigerating load of the JT refrigerator (51) detected by the above) falls below a set value, the displacer driving frequency of the precooling refrigerator (26) decreases or the displacer driving frequency of the shield refrigerator (40) increases. While at least one is done, J
When the refrigerating load of the T refrigerator (51) exceeds the set value, at least one of increasing the displacer driving frequency of the precooling refrigerator (26) and decreasing the displacer driving frequency of the shield refrigerator (40) is performed. And a control means (71) for controlling the displacer drive frequency varying means (72). 15. The cryogenic refrigerator according to claim 14, wherein the operating frequency of the compressor (8) for supplying the high-pressure refrigerant gas to the pre-cooling and shield refrigerators (26), (40) is variable. The control means (71) includes the pre-cooling and shield refrigerator (2
Compressor (8) for supplying high pressure refrigerant gas to 6) and (40)
The operating frequency of the compressor (8) decreases when the refrigerating load of the JT refrigerator (51) decreases below the set value, while the refrigerating load of the JT refrigerator (51) increases above the set value. A cryogenic refrigerating apparatus, which is configured to control so that the operating frequency of the compressor (8) increases when the above operation is performed. 16. The cryogenic refrigerating apparatus according to claim 14 or 15, wherein the JT valve (58) adjusts the pressure of the refrigerant gas.
The high pressure adjusting means (13) is provided, and the control means (71) reduces the refrigerant gas pressure to the JT valve (58) while the JT valve (58) decreases when the refrigeration load of the JT refrigerator (51) falls below a set value. When the refrigerating load of the refrigerator (51) exceeds the set value, the JT high pressure adjusting means (13) is controlled so that the refrigerant gas pressure to the JT valve (58) rises. Characteristic cryogenic refrigerator. 17. The cryogenic refrigeration system according to claim 16, wherein the operating frequencies of the low-stage compressor (5) and the JT compressor (19) are variable, and the control means (71) is the compressor. Regarding the operating frequencies of (5) and (19), when the refrigerating load of the JT refrigerator (51) is lower than the set value, the operating frequencies of the compressors (5) and (19) are lowered, while the JT refrigerator ( A cryogenic refrigeration system characterized in that the operation frequency of the compressors (5) and (19) is controlled to increase when the refrigeration load of 51) exceeds a set value. 18. The cryogenic refrigerator according to claim 9 or 10, wherein JT refrigerator load detecting means (74) for detecting a refrigerating load of the JT refrigerator (51), and JT refrigerator load detecting means (74). ), When the refrigeration load of the JT refrigerator (51) is lower than the set value, the refrigerant gas flow rate to the pre-cooling refrigerator (26) is reduced, while the refrigeration load of the JT refrigerator (51) is set. Refrigerant flow rate adjusting means (4) so that the refrigerant gas flow rate to the shield refrigerator (40) decreases when the value exceeds the value.
And a control means (71) for controlling 6). 19. The cryogenic refrigerator according to claim 18, wherein the operating frequency of the compressor (8) for supplying the high-pressure refrigerant gas to the pre-cooling and shield refrigerators (26), (40) is variable, Means (71) is the above pre-cooling and shield refrigerator (2
Compressor (8) for supplying high pressure refrigerant gas to 6) and (40)
The operating frequency of the compressor (8) decreases when the refrigerating load of the JT refrigerator (51) decreases below the set value, while the refrigerating load of the JT refrigerator (51) increases above the set value. A cryogenic refrigerating apparatus, which is configured to control so that the operating frequency of the compressor (8) increases when the above operation is performed. 20. The cryogenic refrigeration system of claim 19, wherein the JT valve (58) adjusts the pressure of the refrigerant gas.
The high pressure adjusting means (13) is provided, and the control means (71) reduces the refrigerant gas pressure to the JT valve (58) while the JT valve (58) decreases when the refrigeration load of the JT refrigerator (51) falls below a set value. When the refrigerating load of the refrigerator (51) exceeds the set value, the JT high pressure adjusting means (13) is controlled so that the refrigerant gas pressure to the JT valve (58) rises. Characteristic cryogenic refrigerator. 21. The cryogenic refrigeration system of claim 20, wherein the operating frequencies of the low-stage compressor (5) and the JT compressor (19) are variable, and the control means (71) is the compressor. Regarding the operating frequencies of (5) and (19), when the refrigerating load of the JT refrigerator (51) is lower than the set value, the operating frequencies of the compressors (5) and (19) are lowered, while the JT refrigerator ( A cryogenic refrigeration system characterized in that the operation frequency of the compressors (5) and (19) is controlled to increase when the refrigeration load of 51) exceeds a set value. 22. The cryogenic refrigerator according to claim 3 or 4, wherein the shield refrigerator load detecting means (76) detects a refrigerating load of the shield refrigerator (40), and the shield refrigerator load detecting means (76). When the refrigerating load detected by) falls below a set value, at least one of increasing the displacer driving frequency of the precooling refrigerator (26) or decreasing the displacer driving frequency of the shield refrigerator (40) is performed. When the refrigeration load exceeds the set value, the displacer drive frequency varying means is arranged so that at least one of the decrease of the displacer drive frequency of the precooling refrigerator (26) and the increase of the displacer drive frequency of the shield refrigerator (40) are performed. (72)
And a control means (71) for controlling the cryogenic refrigeration system. 23. The cryogenic refrigerator according to claim 22, wherein the operating frequency of the compressor (8) for supplying the high-pressure refrigerant gas to the pre-cooling and shield refrigerators (26), (40) is variable. The control means (71) includes the pre-cooling and shield refrigerator (2
Compressor (8) for supplying high pressure refrigerant gas to 6) and (40)
The operating frequency of the compressor (8) decreases when the refrigerating load of the shield refrigerator (40) decreases below the set value, while the operating frequency of the compressor (8) decreases when the refrigerating load increases above the set value. ) The cryogenic refrigeration system is configured to control so that the operating frequency of (1) increases. 24. The cryogenic refrigerator according to claim 9 or 10, wherein the shield refrigerator load detecting means (76) detects a refrigerating load of the shield refrigerator (40), and the shield refrigerator load detecting means (76). ), The refrigerant gas flow rate to the shield refrigerator (40) decreases when the refrigerating load detected by the above (3) decreases below a set value, and when the refrigerating load increases above the set value, the precooling refrigerator ( Control means (71) for controlling the refrigerant flow rate adjusting means (46) so that the refrigerant gas flow rate with respect to 26) decreases.
And a cryogenic refrigerating device. 25. The cryogenic refrigerator according to claim 24, wherein the operating frequency of the compressor (8) for supplying the high-pressure refrigerant gas to the pre-cooling and shield refrigerators (26), (40) is variable. The control means (71) includes the pre-cooling and shield refrigerator (2
Compressor (8) for supplying high pressure refrigerant gas to 6) and (40)
The operating frequency of the compressor (8) decreases when the refrigerating load of the shield refrigerator (40) decreases below the set value, while the operating frequency of the compressor (8) decreases when the refrigerating load increases above the set value. ) The cryogenic refrigeration system is configured to control so that the operating frequency of (1) increases.