JPS62268964A - Cryogenic refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. A detailed explanation of the invention (industrial application field) The present invention is based on a pre-cooling refrigeration circuit that expands a refrigerant gas such as helium gas, and a J-1' circuit (Joule-Thomson). It has a cryostat (cryogenic circuit) and generates an extremely low temperature in the raw part with a low temperature zone () to avoid operating equipment operating at a temperature of t°C. 11 Regarding refrigeration, especially the operation of low-temperature operating equipment (C) intersects with measures to reduce disturbances.

(Prior art) Traditionally, this (1,000 cryogenic temperatures;
\Thulium is used as a refrigerant, and the high-pressure l\Thulium that has been compressed by one step in the compression chamber is expanded before expansion to shield the low temperature generation part in the fly Ostara mill from the outside. Pre-cooling cooling 1
East circuit and separate pressure H? When the cum gas discharged from the machine and compressed is pre-cooled in the pre-cooling refrigeration circuit,
The pre-cooled helium gas is further pumped through the J-T valve.
J-
Helium refrigeration vats with T-circuits are well known.

By the way, for such a helium refrigerator, the refrigeration cycle of the pre-cooling refrigeration circuit is usually G-M'Nicle (
In this case, gas flow due to high/low pressure switching of expansion 1]II, collision between the displacer and cylinder, or "il/' This may occur due to expansion and contraction of the cylinder due to low pressure switching.
However, as it is, it is difficult to apply the optical detection used in 2-spectroscopic research because μ7nΔ-Goo is extremely small (which avoids commotion) to sensors and the like.

Therefore, conventionally, when the photodetection sensor is activated, the operation of the entire refrigerator is stopped each time, and the temperature at the sensor part 1 is adjusted by using the heat capacity of the sensor part d'3 and the heat station. To cool it down, the necessary temperature must be exceeded to ensure that the rules are met.

(The problem that the invention is trying to solve) However, if the operation of the entire cooling chamber is stopped when the light detection sensor is activated, the following problem will occur. .

However, when operating the refrigerator, helium gas is supplied!
The f is maintained at about 20 atm and the return pressure is kept at about 1 atm, and some of the helium gas after passing through the J-T valve is liquefied! l! It is maintained at an extremely low temperature of 84°C.

However, from this state, when the operation of the refrigeration system is stopped at tl4, the pressure in J-Chome Road is balanced at about 8 atmospheres, and as shown in Figure 6, the helium liquid at the sensor section is instantaneously released. supercritical pressure is reached at a temperature of 5.5 to 8 K.
It will rise to.

In addition, in general, when the temperature reaches an extremely low temperature, the specific heat is small, so the temperature of each part becomes small, and if there is even a slight heat load, it is prohibited to suddenly increase the temperature. j','L.

Therefore, in order to reduce the noise level of sensors that utilize the superconducting phenomenon, the temperature will rise rapidly, and as a result, the superconducting phenomenon may be broken, or thermal noise may increase. This causes problems such as the measurement becoming U3ff.

The present invention has been made in view of the above-mentioned points, and its purpose is to improve the low temperature refrigerating machine such as the helium refrigerator having the above-mentioned pre-cooling refrigeration circuit and J-T circuit. When a separate device is activated, the operation of the expander, which is the source of vibration, is stopped, while the low-temperature operation inside the cryostat continues its operation for the J-D circuit that cools the device.
It is necessary to extend the distance between ff and l1 for low-temperature operation (XI ``holding lh at an extremely low temperature to a large extent ri, so that the measurement can be carried out with sufficient support /ν). .

(Means for Solving the Problems) In order to achieve this object, the solution means of the present invention, as shown in FIG.
(C) and 1-cho, Hi: I number (2>-(-1 -1 condensed refrigerant gas 81 shadow 1 Ugly evil (6)
'' (1 type 11 is lengthened to generate a cryogenic temperature, and the cryogenic temperature is expanded to +fj machine (6) -1 to station (9), (1
0)! :'+y! ``T pre-cooling refrigeration circuit (1),
By compression (2).

The high-pressure refrigerant gas from (23) is precooled by heat exchange in the heat stations (9) and (10) of the expander (6),
The pre-cooled refrigerant gas is expanded by Joule-Thomson to create a raw part (C1) in the lower part of the cryostand (C).
A cryogenic temperature shines inside. A helium freezing gate with a no-1 circuit (20) is assumed.

-C1 First, start the operation of the pre-cooling refrigeration circuit (1).
, tl-, the expander stop means (6'l) and (62) are completed.

Further, when the low-temperature operation separate device (S) is activated, the expander stop means (61) and (62) are activated to activate the pre-cooling refrigeration circuit (
1) A configuration in which a control (111) means (60) is provided for controlling the operation of the expander (6) to be stopped.

(Function) With the above configuration, in the present invention, the low temperature production lII reactor (S
) is activated to cool it down to a cryogenic temperature (11), both the pre-cooling refrigeration circuit (1) and the J-T circuit (20) are operated. At this time, compressor (2)
The high-pressure refrigerant gas discharged from the expansion machine (6) expands to produce a cryogenic temperature, and this cryogenic temperature is maintained at the heat stations (9) and (10) of the expansion machine (6). Moreover, in the J-T circuit (20), L! +iii machine (2>,
The high pressure refrigerant gas from (23) is sent to the heat station (9) of the expander (6).

After being precooled by heat exchange in (10), Joule (Hemson) expands in the J-T valve (36) in the cryostat (C) and an extremely low temperature is generated in the low temperature generating part (C1). Low-temperature operating equipment (S) is cooled.

On the other hand, when operating the low temperature operating equipment (S), the expander stopping means (61) is controlled by the control means (60).
), (62) are operated, and only the operation of the expander (6) of the precooling refrigeration circuit (1) is stopped, while the J-T circuit (2
0) continues. Therefore, in this case, the operation of the expansion 11 of the pre-cooling refrigeration circuit (1) (6) is stopped, so the operation of the expansion valve 11 of the pre-cooling refrigeration circuit (1) is stopped in order to prevent the generation of vibrations that the low-temperature regulator (S) dislikes. UIC can actually do this.

In addition, since the operation of the J-T circuit (20) is continued, the refrigerant gas in the J-T circuit (20) is transferred to the expander (6).
heat station (9).

('l O> can be used for Joule-Thomson expansion while pre-cooling, and the refrigerant pressure in the operating equipment is controlled by the expansion machine (6).
The pressure is maintained at the appropriate level as during operation, and there is no sudden temperature rise in the operating equipment, so the operating equipment is kept at an extremely low temperature for a long time. It is possible to stabilize the operation of the.

('1st Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of a binary, two-stage compression cycle helium refrigerator according to the first embodiment of the present invention, and (0) shows the structure of a helium refrigerator for spectroscopic investigation of low-temperature operating equipment that operates at extremely low temperatures. The low temperature generating part (C) keeps the light detection Zenza (S) in a cool state.
Cryostat with 1) inside, (1) is the J of the rear
- T circuit (20) 76 (Improved Solvay type pre-cooling refrigeration circuit that compresses and expands helium gas to pre-cool helium gas, I: 20) 4.1; Helium gas to generate low temperature to l The pre-cooling refrigeration circuit (1) extends between the pre-cooling silica unit (A) and the Fly Ostara 1-(C). Then, J-1 [circuit (2
0) is installed in parallel to the J--T side compressor unit 1 surrounded by (B) and the cryostat (C).

The pre-cooling compressor unit (A>) is a pre-cooling compressor (2) that compresses helium gas, and the compressor (2) uses compressed high-pressure helium gas to lubricate the compressor (2). The suction device is equipped with an oil separator (3) that separates and removes oil, and a suction device (4) that sucks and removes impurities such as moisture and impure gas from the helium gas that has passed through the oil separator (3). The cryostat (4) is connected to the cryostat (4) via the high pressure side pipe T'4+ (5).
C) is connected to the high-pressure side inlet (7a) of the casing (7) to the expander (6) which has a capacity of 1tXH.

The expansion machine (6) includes a cryostat (C), a gaging (7), and a cylinder (8) connected to the end of the casing (7). (J), and the outer periphery of the cylinder (8) is
・The first) inserted into the low temperature generating part (C1) of <C)
l: l, station (10) and the first heat exchange (9) are being pierced. Inside the casing (7), there is a high pressure side valve I that opens every time it rotates.
The helium gas flowing from J (7a) is transferred to the cylinder (
8) A rotary valve (not shown) that supplies the inside of the rotary valve and a valve saver (11) that drives the rotary valve are arranged.

-No.j, inside the cylinder (8), although not shown, there is a slack piston that reciprocates according to the opening and closing of the rotary valve]
... and integrally engage the slack piston, tt-,! !
,! Move the inside of the cylinder (8) by 8 degrees with 4 hands.
The display area that inflates helium gas is +lX:+j. And the above cylinder (8) glue 11 heat 1 ~ station (9) is Fly Ostara! - It is in thermal contact with the radiation shield part (C2) arranged to surround the low salt generating part (C1) in (C), and high pressure is generated by opening the rotor 1 valve at (6). The first and second heat stations (9), (10) generate a low temperature state by expanding I\1 gas in the cylinder (8) and apply the low temperature state to the cylinder (8). ), and cooled the width side shield part (C2) which is in thermal contact with the first heat station (9) to a low temperature.
C1) from the outside by radiation shielding.

In addition, i, +,
: The pressure side outlet (7b) that allows low pressure helium gas to come out after expansion is opened, and the low pressure side outlet (7b) (monthly
xo: Side piping <12>'! - The pressure bottle (13) for pre-cooling is placed in contact with the bottle (13) for pre-cooling, and the bottle (13) is placed in the press-1 dairy unit for pre-cooling (△)
=1〒It is connected to the suction side of ir++a (2), and the low pressure helium gas discharged from the expander (6) is
A) BJ is absorbed by the Nargiboru (13) and used in one stage of the compressor (2). The high pressure gas discharged from the pre-cooling compressor (2) is placed on the pipe (3) and the absorber (4).
) is fielded and supplied to the expansion machine (6), and the expansion machine <6)
Heat station (9), (
10) Lower the temperature and fry Ostara + ~ <C>
If the low salt generation part (C1) inside is shielded from radiation,
．． The precoolers (31) and (33) of the Jho are precooled, and the expanded low-pressure hem gas is sent to the compressor (2) via the regiboru (12). Back to rIJ and it is configured in the same way.

On the other hand, the J-T side compressor 2 units (B) (this is a low stage compressor (21) that compresses helium gas to a predetermined pressure) J, and the high pressure helium discharged from the first compressor (21) An oil separator (22) that separates and removes lubricating oil for the compressor (21) from the gas, and a high-stage compressor (23) that compresses the high-pressure helium gas that has passed through the oil separator (22) to an even higher pressure. Then, an oil separator (2/removes the lubricating oil for the compressor (23) from one volume of gas to the iFI pressure discharged from the compressor (23), and the oil separator (24) is An absorber (25) is installed to remove impurities from high-pressure helium gas.

J, ta, t are written on the primary side ti.
, J, and the q heat exchange between the helium gas passing through the secondary side, respectively, the first to third J-1 heat exchange M
, (26) to (28) are fitted, and among these J-1 heat exchangers (26) to (28), the second and third J-
The T heat exchanger (27>, (28) is
It is arranged in the mQ dimension shield' part (C2) of C). The primary side IJ of the first J-T heat exchanger (26),
It is connected to the adsorber (25) of 11 J-T side compression (units) to (B) via the high pressure side pipe (29).

In addition, the above “1st J” and “2nd” no-T heat exchanger (2
6) and (27) are connected to each other via an adsorber (30) and a first precooler (31) disposed on the outer periphery of the first heat station (7) of the expansion 3N<6). 2nd and 3rd J-T
Heat exchanger (27).

Similarly, the primary sides of (28) are connected to each other via an adsorber (32) and a second precooler (33) arranged around the outer periphery of the second heat station (8) of expansion + geometry (6). It is connected. Furthermore, the primary side of the jth JT heat exchanger 2 (28) is a cold NI device (1☆7J) supported by the lower end of the cylinder (8) of the expander (6) and placed in the low temperature generating section (C1). 34) is connected via an adsorption device (35) and a J-T valve (36) that expands 11 kg of helium gas to 1 to 1 joule.

The cooler (34) passes through the secondary sides of the 3d and 2nd J-T heat exchangers (28>, (27>)
Heat exchange; connected to the secondary side of brown (26), said No. 1 J-1
The secondary side of the heat exchanger (26) is connected to the above J-Ti111I Pressure 1) via the low pressure side piping (37).
11 adjacent to the intake side of Nii (Urulow Dan) Ojikaku (2'1)
>'a has been done. Therefore, tangent δ to the above 21172 series
Two pressurized locomotives +X! ! (21>, (23>) compress helium gas to high pressure and fly Ostara 1~(
C) side, and then it is sent to the first to third Jl heat exchangers (26) to (28) of (C) and then returned to the J-T side compressor unit (B). At the same time, the first and second precoolers (3-1) and (33) exchange heat with the first and second heat stations (9>, (10)) of the expander (6). After exchanging and pre-cooling, use the J-Cho ↑ (36) to lengthen the Gichol-Thomson expansion bow, and use the cold IJJ device (34) to 1 atm, about 4
After that, the low pressure helium gas is transferred to the 14th to 3rd J-l heat exchangers (26) to (2).
8) through each secondary side of the J-T side compressor unit (B)
(low-stage compression) (21) for recompression.

In addition, the compressor (2) of the compression brewing unit (△) for pre-cooling is described in
aLJ: UJ-T side compression gc-knit (s> (7)
The two compression + a (21) and (23> structures and their surroundings) are constructed in a similar @ structure, and in the figure, (40)
is a discharge gas coil installed in the middle of the flow path from the discharge side of each compressor (2>, (21>, (23>) to the oil separator (3), (22>, (24>). Discharge gas coil (
40) &r! , each compression before compression).

The casing (not shown) of (21>, (23)) is wound around the outer periphery of the casing (not shown). A cooling water coil (41) through which cooling water flows over the entire surface is wound approximately flat with the above-mentioned outlet gas coil (40), and this cold water coil (4'1) The cooling water flowing through the compressor cools the high-temperature, high-pressure helium gas discharged from the compressors (2>, (21), (23) and flowing inside the discharge gas coil (40).

Moreover, (42) is each compressor (2), (21>).

(23) The cooling water coil (4
1) Ichi is a curved coil wound approximately parallel to the above.
The upstream end of the nuclear oil coil (42) has a number of pressed navy blue;)(2>,(
In the oil reservoir at the inner bottom of the casing in 21> and (23>,
At the downstream end, condensation condensation <2>, (21>, (2)
3) are respectively connected to the suction side of the compressor (2>
, (2'!>.

(23) along with helium gas is supplied to the iT,'ll sliding coil (42) in the casing.
(Cooled by the cooling water in the cooling water coil (41)) Jl
After the injection, the orifice (/13) of the injection pipe (/14) is used to inject the helium gas into the suction helium gas.

Furthermore, (45) is the J-T side pressure side compressor unit (B
) is a connection box that connects the discharge side of the oil separator (22) and the discharge side of the adsorber (25). A high-pressure control valve (46) for controlling the diaphragm, a gas ballast tank (47) for storing high-pressure helium gas flowing out from the high-pressure control valve (46), and an oil separator for discharging the high-pressure helium gas in the tank (47). (22) Low-stage compression by supplying to the discharge side is (2
An intermediate pressure control valve (48) for controlling the discharge volume of 1) is provided.

As a feature of the present invention, the pre-cooling/freezing cycle "M('
Compressor (2) and expander (6) in I) and both compressors <21>, (
23> is operated and controlled by a control device (60). The valve shutter (11) of the expander (6) is connected to the control device (60) via a shut off valve stop device (61) for stopping its operation (1' 3.The operation of the valve motor (11) caused by the operation of F↑(61) is stopped to stop the operation of the valve motor (6). The control device (60) operates the motor operation stop device (61) when the photodetection valve (3) is activated (in total) to stop the expansion machine (6) in the pre-cooling refrigeration circuit ('1). ) and stop the operation, and carry out the above J
- It is configured to inherit the circuit 117 of the T circuit (2o) and to pass through the C circuit.

In addition, the oil separator (
3) and the adsorber (4), the low-pressure side pipe (12) immediately upstream of the Lijtor (13), and the relief pipe (50) with the 4.1 inner relief valve (49) interposed therein. The inner relief valve (49) reduces the edge/tum gas from the IT IN (2) that does not flow into the expander (6) when the expander (6) stops operating. After that, the process returns to Shinku (2).

Next, the operation of the helium-cooled εl Jiff of the above embodiment will be explained.

Light detection lens in (C) to fly shoes l → No (S) non-activation 1! 4 to 1, 1, morph activation + ♀ stop device (61)
is in operation, in this normal state (light detection sensor υ(S
), cooling is performed.

To explain this action in detail, the two compressors (21>, (23>) of the J-1 circuit (20), the first compressor (2), and the compressor (2) of the precooling refrigeration circuit ('1) are started. cooling ε)1) When the shallow is in steady operation state, the pre-cooling refrigeration circuit ('1) (January ゛J
Fly Ostara 1~(C) side expansion 1'J, (6) teE+,: &+! The high-pressure helium gas supplied from Iku (2) expands, and as this gas expands, the cylinder (
8) each heat station (9), (10) d3J,
The temperature of the radiation shield part (C2), which is in thermal contact with the first heat station (9), decreases, and the low temperature generating part (C1) in the cryostat (C) is shielded by copper in width from the top part. .

Meanwhile, at the same time, J-
The 1-noon gas that returns via 7 circuits (20) is sucked and compressed by the low-stage compressor (21), and is cooled down to room temperature 300K by cooling water in the surrounding cooling water coil (41). After the l\lium gas is separated into oil components in an oil separator (22), it is sucked and compressed in a direct 1 (2) compressor (23). is the cooling water coil (4:) around the compressor (2:, 3).
In step 1), the oil is cooled to room temperature 300K with cooling water, and after the oil is separated in the oil separator (24), impurities are adsorbed in the shield absorber (25). ).

The high-pressure helium gas supplied to the cryostat (C) side enters the primary side of the 1st J-] heat exchanger (26),
Heat is exchanged with the low pressure helium gas on the secondary side returning to J-T side 1 condensation unit i ~ (6)
It is cooled to 0K, then the expansion number (6) is 50 to 6.
The first case cooled to 0K enters the first precooler (31) on the outer periphery of the steel tube (9) and is cooled to about 55K. This cooled gas (enters the primary f!Ill of the second J-T heat exchanger (27) and returns to the low-pressure helium on the secondary side of the JT side compression chamber. After being cooled down to about 20K by heat exchange with the gas, the second pre-cooling chamber on the outer periphery of the 2nd neat stage 3]n (10) is cooled to 11]-20K of the expander (6). 33) and cooled down to about 15K.Furthermore, there is a person on the primary side of the 30th heat exchanger (28).
-1 side pressure i! : It is cooled to about 5K by heat exchange with the low-pressure helium gas on the secondary side that enters the i+XM unit 1-(B), and reaches the J-T valve (36). This J-T valve (36)
- (Gas/liquid at 1 atmosphere and gas-liquid at 1 atmosphere) is mixed with helium and/or supplied to the cooler (34). Soshi-Jinko's Reigetsu 1 vessel (34) has the above gas-liquid mixture! Ryo no l
\! The hot valve latent heat of the acid part in the gas is used to liquefy or recondense the cooled gas of the photodetector sensor (S) or other gases to be removed.

After 1-4 hours, the low-pressure helium gas returns from the cooler (34) to the secondary side of the third J-T heat exchanger (28).
The helium gas on the primary side is cooled to a temperature of about 300 K in the second and I J-T heat exchangers (27) and (26). After that, return to the J-T side compression compensation unit 1~<B). From then on,
Similar 4 noise cycles are repeated to perform cold i-east operation.

In response to this, when measuring each physical quantity while avoiding the activation of the light detection sensor (S), 1111 and 11 units (
60), the J-7 circuit (20) is operated.
(Continue as it is) On the other hand, the 7-tar operation F stop device t (6
゛l) is activated and the pre-cooling refrigeration circuit (1) (J,;
The operation of valve 7 (-11) of GJ Le expansion IHi (6) is stopped, thereby stopping the operation of only the expansion number (6). Therefore, vibrations with an expansion number (6) do not occur, and the vibration force applied to the photodetection lens (S) can be reduced to 4.

In addition, although the operation of the expander (6) is stopped, the monolithic transistors (9) and (10) are maintained in the 1◇low-down state, so the J-LT circuit (20) is (The high pressure helium gas from the lower compressor (23) is
r"';' While pre-cooling at the heat station (9), (]0) of the stopped one-dish expansion machine (6), the J-1'-valve (
It is possible to achieve a cryogenic temperature of 151° by Joule-Thomson expansion at 3G). For this reason, the helium pressure in the cold H1 cooler (34) is
As in the J1 operation, the predetermined pressure ('1 atm) is maintained, and as shown in FIG. 2, a drastic temperature rise in the cooler (34) is avoided, so that the light detection temperature (S) is kept at +1. The measurement operation can be performed stably by keeping the temperature at the harvesting temperature for one hour.

In addition, FIG. 2 shows the sensor unit (cooler (34)
) compared to the conventional (pre-cooling refrigeration circuit ('1)
) and stopping the operation of the J-T circuit (20)).

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention. For the same parts as in Figure 1, the same symbols are hidden and detailed explanations are omitted.
1i21η"ru.

In other words, in this second embodiment, the color scheme on the high voltage side of the cooling circuit (1) and (b) are changed immediately after the expansion (6) is stopped. An electromagnetic on-off valve (62) as one means of expansion is installed in the middle, and a control device (
60') closes the on-off valve (62), thereby cutting off the supply of helium gas to the +W clothing machine (6) and substantially stopping the operation of the expander (6). (The structure is as follows. Therefore, this embodiment also has the same structure as the first embodiment.

It is possible to achieve various effects.

In addition, as a modification to this embodiment, an opening/closing button? (62
) may be changed to the low pressure side piping (12), and even '
, jB low-pressure side piping (5>, (12>) may be provided, and supply and discharge of helium gas useful for the expander (6) may be stopped at certain times.

(Third Embodiment) FIG. 4 shows a third embodiment, which is applied to a helium refrigerator having a single circuit.

In the case of this embodiment, the oil separator (24) of the J-T circuit (20') and the low pressure side pipe (1
2) is connected, and the high pressure side piping of the J-T circuit (20') is connected to the high pressure side piping (5) of the precooling refrigeration circuit (1').
It has been made common. Further, the primary side of the first J-T heat exchanger (26) in the J-T circuit (20') is connected to the high-pressure side pipe (5) of the pre-cooling refrigeration circuit (1'). In general, the connecting pipe (45), gas parast tank (47), etc. in the J-T circuit (20') are omitted.
Instead, the high pressure side piping (5) of the precooling refrigeration circuit (1')
and low pressure side lock 'l'? (12) is connected by a connecting pipe (51), and the connecting pipe (51) has one joint pressure control valve (52) and a gas ballast tank <53> located around j from the upstream side.
, a low pressure control valve (54) is provided, and the rest is the same as No. 1 above.
The structure is similar to that of the embodiment.

Therefore, in this third embodiment, approximately half of the high helium gas discharged from compressor A (2) is supplied to (6), and the expansion is performed by (6). After that, return to the compression gate (2) via the low pressure side lock (12). Also, the remaining half is the No 1 circuit (20') f, 7)
Flows to the J-T valve (36), and its J-1 [valve (36)''
C Joule-Thomson low pressure side placement after expansion 1137)
1 compression (21>, <23>), compressed by these compressions (2'l), (23) and then 1" - element 19 refrigeration circuit (1') Compression (into (2)! Expansion! It is inhaled together with the gas from the expansion machine (6) into the return from the expansion machine (6). Therefore, in this example, when the light detection sensor (S) is activated, the expansion machine (6) is the valve sweater (11)
Since the operation is stopped by the stoppage of
It is necessary to keep the sensor part at an extremely low temperature by grinding it for a long time while reducing the vibration.

(Fourth Embodiment) FIG. 5 shows a fourth embodiment, in which the helium gas supply to the expander ((5) is In order to shut off the discharge, we installed an electric Rλ shutoff valve (62) at 71 in the second embodiment and Mr.
Q 77, and the effects of this embodiment 1 and 5 above can be clearly seen.

It should be noted that the present invention is not limited to the above-described embodiments, but includes various other modifications. ) 11 For example,
The valve motor (11) of the expander (6) in the above embodiment
) may be combined so as to simultaneously stop the operation of (6) and stop the supply and discharge of helium gas to (6).

In addition, before compression (2) of the pre-cooling refrigeration circuit (1), (1')
It is also possible to stop the operation of the expander (6) by stopping the supply of helium gas to the expander (6).

In general, the present invention is useful for compression cycle helium refrigeration as in the embodiments described above, as well as for other types of helium refrigeration.
It can also be applied to Toki. For example, it is applied to a helium-cooled refrigerator having a pre-cooling refrigeration circuit equipped with a G-M' large cycle expander. All you have to do is stop it. Furthermore, it goes without saying that the present invention can be applied to cryogenic refrigerators that use refrigerants other than helium.

(Effects of the Invention) As explained above, according to the invention, the first high school junior high school junior high school student's sword was placed inside the taliostat for cooling and maintaining the Joule Thomson mover. -1 circuit and a pre-cooling refrigeration circuit that pre-cools the refrigerant gas of the J-King circuit to the right J-filter cryogenic refrigerator.
・By avoiding stopping the operation of the expander in the pre-cooling refrigeration circuit when the low-temperature operation separate device is activated,
J-1 while eliminating the occurrence of one rib due to the operation of the expander.
゛By continuing the operation of the circuit, it is possible to suppress the pressure rise of the refrigerant gas in the operating equipment and eliminate the rapid temperature rise.
It is possible to support the operation of low-temperature operating equipment that is sensitive to vibration by keeping it at a low temperature for a long time.

[Brief explanation of the drawing]

Fig. 1d3 and Fig. 2 show the first embodiment of the present invention, Fig. 1 is an overall configuration diagram of a helium refrigerator, and Fig. 2 shows a portion of the bottle 4 when the photodetection sensor 4 is activated. Temperature parable. 5 Qr.
FIGS. 3 to 7F'55, which are characteristic diagrams without showing characteristics, are equivalent to FIG. 1, showing second to fourth embodiments, respectively. Figure 6 shows the helium refrigerator pre-cooling circuit 1 Song J. Seven linyl diagram of the gas cycle in the j-1-rg circuit. 1:1), ('1')...Pre-cooling refrigeration circuit, (
2)... 1 soil shrinking machine for pre-cooling, (6)...j Changshu) number,
(9), (10)...heat station, (11)
...Valve motor, (20>, (20' door)
・J-T circuit, (21)...low stage compression crotch, (23)・
...High stage compressor, (26) to (28)...J-T heat exchanger, (31), (33)...Precooler, (34)...
・Cooler II, (36)...JTT valve, (60), (6
0')...control device, (61)...motor operation stop device, (62)...electromagnetic on-off valve, (C)...Taraioscook j・, (C1)...low temperature generation 8( 9, (
C2)...Shielding part, (S)...Light detection sensor.

Claims (1)

[Claims] (1) A cryostat (C) that has a low temperature generating part (C_1) for cooling and maintaining low temperature operating equipment (S) that operates at extremely low temperatures, and an expander (6 ) to generate a cryogenic temperature, which is then transferred to the heat stations (9), (10) of the expander (6).
The pre-cooling refrigeration circuit (1) held by the compressors (2), (2)
The high-pressure refrigerant gas from 3) is pre-cooled by heat exchange in the heat stations (9) and (10) of the pre-cooling refrigeration circuit (1), and the pre-cooled refrigerant gas is expanded by Joule-Thomson and sent to the cryostat (C). Low temperature generation part (C_1)
The cryogenic refrigerator is equipped with a J-T circuit (20) that generates a cryogenic temperature inside the cryogenic refrigerator, and an expander stop means (61) that stops the operation of the expander (6) of the pre-cooling refrigeration circuit (1). ),
(62) and a control means (60) for controlling the expander stop means (61) and (62) to operate when the low-temperature operation equipment (S) is activated. Low temperature refrigerator.