JP2509705Y2 - Liquid helium replenishing device - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for intermittently automatically supplying liquid helium to an object to be cooled.

[0002]

2. Description of the Related Art Conventionally, a liquid helium replenishing device is generally controlled so as to pressurize a liquid helium storage container on the basis of a signal detecting a liquid level of liquid helium for cooling an object to be cooled ( "Cryogenic Engineering", 1992, Volume 27,
No. 5, pp. 392-397). If the coolant is liquid nitrogen etc., there was no particular problem with the above method, but if the coolant is liquid helium, the density is low, so supply helium gas from the outside or install a heater in the storage container. It was carried out that the liquid helium was forcibly gasified and pressurized by mounting and heating.

[0003]

However, in the case of the above-mentioned conventional liquid helium replenishing device, when the liquid helium in the storage container is inadvertently lost during replenishment, a pressurized gas is supplied from the outside. If the supply of the heater power and the heater power is continued, the object to be cooled will be heated. In this case, there is no problem if the remaining amount of liquid in the storage container is monitored by a liquid level sensor or the like, but there is a problem that instruments such as this liquid level sensor are expensive and economically disadvantageous. It was The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid helium replenishing device capable of controlling execution / stop of replenishment by a simple and inexpensive detector.

[0004]

In order to solve the above problems, a liquid helium replenishing device according to the present invention has an on-off valve connected to a vapor phase opening to supply liquid helium for cooling an object to be cooled. A storage container for storing, a helium remaining amount detecting means for detecting the presence or absence of the remaining amount of liquid helium in the storage container, and outputting a helium remaining signal when liquid helium remains in the storage container, and the object to be cooled. A liquid level detecting means for detecting a liquid level of the liquid level and outputting a liquid level detection signal; an adiabatic transfer pipe for supplying the liquid helium to the object to be cooled from the storage container; Replenishment control means for outputting a replenishment control signal for controlling the start or end of replenishment of liquid helium, and controlling the on-off valve based on the helium residual signal and the replenishment control signal and controlling the gas in the storage container. A pressurizing means for pressurizing the portion at a predetermined pressure or less, the helium residual amount detecting means winds a superconducting wire around an electric resistor, and the electric resistor and the superconducting wire are connected in series. Connected to form a series circuit, a direct current is applied to the series circuit at the time of measurement, and when the superconducting state is broken due to the helium residual amount detecting means being exposed to the outside of liquid helium, between the both ends of the superconducting wire. The presence or absence of the remaining amount of the liquid helium is detected by utilizing the generation of the voltage, and the pressurizing means has a heater.

[0005]

According to the present invention having the above structure, when the liquid helium in the storage container is used up, the replenishment control signal for starting the replenishment is not output, so that the heated gas is sent to the object to be cooled. Does not occur. Therefore,
The reliability and safety can be improved even when performing automatic operation. In addition, since the means used for detecting the presence or absence of the remaining amount of liquid helium does not include moving parts immersed in liquid helium, there are problems such as freezing of moving parts in low temperature environments, wear, and clogging due to impurities. Does not occur.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a liquid helium replenishing device 1
Is a liquid helium storage container 2 that is a storage container for liquid helium L, a supply path system 3 that supplies liquid helium L to the object to be cooled C, and liquid helium L in the liquid helium supply device 1.
Sensor system 4 for monitoring the liquid helium, automatic replenishment control system 12 for controlling replenishment of liquid helium L, and pressurization system 5 for applying pressure to liquid helium storage container 2 under the control of automatic replenishment control system 12.
And are provided.

The object to be cooled C is constructed so as to be able to store liquid helium L therein, and the liquid level height of the liquid helium L must always be maintained within a certain fixed range. . The liquid helium storage container 2 has a capacity several times or more the amount of liquid stored in the object to be cooled C, and a gas-liquid sensor 14 and an electric heater 17 are provided near the bottom thereof.
have.

In the above-mentioned replenishment path system 3, a heat-insulated transfer pipe 6 which communicates the bottom of the object to be cooled C with the bottom of the liquid helium storage container 2, and a gas as a countermeasure against liquid helium L which is constantly and gradually vaporized. Release ports 7a and 7b and solenoid valves 8a and 8b connected to the gas release ports 7a and 7b
And a check valve 9 is provided. Here, the solenoid valve 8b corresponds to an opening / closing valve.

Normally, the solenoid valve 8a is closed and the solenoid valve 8b is open. Further, the helium gas that is routinely generated from the object to be cooled C and the liquid helium storage container 2 is discharged from the check valve 9 to the external system through the gas discharge ports 7a and 7b.

The sensor system 4 has a liquid level sensor 10, a liquid level gauge 11 and a gas-liquid sensor 14. The liquid surface sensor 10 is attached to the object to be cooled C in order to detect the liquid surface height of the liquid helium L. The liquid level sensor 10 is electrically connected to a liquid level gauge 11 for measuring the liquid level height of the liquid helium L, and the liquid level gauge 11 is a liquid level monitoring controller in the automatic replenishment control system 12 described above. It is connected to 13. Liquid level sensor 10
When detecting the liquid level of liquid helium L, outputs a liquid level detection signal to the liquid level gauge 11. The liquid level gauge 11 measures the liquid level height of the liquid helium L in the object to be cooled C based on this liquid level detection signal, and outputs the liquid level signal to the liquid level monitoring controller 1
Output to 3.

The automatic replenishment control system 12 is a liquid level monitoring controller 1.
3, a supply controller 15, and a pressurizing controller 16. When the liquid level monitoring controller 13 receives the liquid level signal from the liquid level gauge 11, the liquid level monitor controller 13 determines the object C to be cooled according to the contents of the signal.
The liquid level of the liquid helium L in the inside of the object C is judged whether or not the liquid level height is below the minimum level of the predetermined range or above the maximum level of the predetermined range. When the surface height falls below the minimum level within the predetermined range, a liquid level drop signal is output to the connected replenishment controller 15, and when the level rises above the maximum level within the predetermined range, a liquid level rise signal is output. . Here, the liquid level sensor 10, the liquid level gauge 11, and the liquid level monitoring controller 13 constitute liquid level detection means,
The liquid level drop signal or the liquid level rise signal corresponds to the liquid level detection signal. The function of the liquid level monitoring controller 13 is as follows:
Can be included in 1.

On the other hand, a gas-liquid sensor 14 is mounted near the bottom of the liquid helium storage container 2 to detect the presence or absence of liquid helium L near the bottom of the liquid helium storage container 2, and as a result, Is output to the replenishment controller 15 in the automatic replenishment control system 12.

Next, the structure of the gas-liquid sensor 14 will be described with reference to FIG. As shown in FIG. 2, the gas-liquid sensor 14 includes a superconducting wire 2 around the electric resistor 20.
1 is wound, the electric resistor 20 and the superconducting wire 21 are connected in series to form a series circuit, and a direct current is caused to flow through the series circuit by the current lead wires 22 and 22 during measurement. When this superconducting wire 21 exists in liquid helium L,
Since it has been sufficiently cooled to the ultra-low temperature state, it becomes a superconducting state, and no potential difference occurs between the voltage terminals 23.

However, the gas-liquid sensor 14 is replaced by liquid helium L.
When exposed to the outside and exposed to the helium gas, the temperature of the superconducting wire 21 rises due to heat generation in the electric resistor 20, so that the superconducting state is broken and the voltage between the voltage terminals 23, 23 at both ends of the superconducting wire 21. A voltage is generated at. The supply controller 15 determines whether liquid helium L is present or not depending on the magnitude of the voltage value.

When it is confirmed from the signal from the gas-liquid sensor 14 that liquid helium exists near the bottom of the liquid helium storage container 2, the object C to be cooled of the liquid helium L is C.
In this case, the liquid level monitoring controller 13 indicates that the liquid level of the liquid helium L in the object to be cooled C is below the minimum level within the predetermined range. When the liquid level drop signal is received, the replenishment controller 15 outputs a replenishment start signal to the pressurization controller 16.

If it is confirmed by the signal from the gas-liquid sensor 14 that liquid helium does not exist near the bottom of the liquid helium storage container 2, it is said that the liquid C cannot be replenished to the object C to be cooled. Therefore, in such a case, the supply stop signal is output to the pressurization controller 16. This makes it possible to prevent so-called "dry heating". Further, since the gas-liquid sensor 14 used for detecting the presence / absence of the remaining amount of liquid helium does not include a moving part immersed in the liquid helium L, the moving part is frozen in a low temperature environment, and wear or wear due to impurities causes Problems such as clogging do not occur.

Even if it is confirmed from the signal from the gas-liquid sensor 14 that liquid helium exists near the bottom of the liquid helium storage container 2, the liquid level of the liquid helium L in the object to be cooled C is predetermined. If the liquid level drop signal indicating that the level has dropped to the minimum level or lower has not been received, replenishment is not necessary, so the replenishment controller 15 determines the pressurization controller 16
A supply stop signal is output to.

If it is confirmed by the signal from the gas-liquid sensor 14 that liquid helium does not exist near the bottom of the liquid helium storage container 2, it will cause troubles as it is. Measures such as notifying the operator of the occurrence of an abnormality by turning on the lights etc. or sounding an alarm buzzer are taken. Further, also in the case of the liquid level rise signal, if it continues abnormally for a long period of time, it is determined that the situation is abnormal also in this case, and the replenishment controller 1
At 5, a warning lamp or the like (not shown) is turned on or an alarm buzzer is sounded to notify an operator or the like of the occurrence of an abnormality. In order to further enhance safety, the solenoid valves 8a and 8b are returned to their original positions and the heater 17
The control procedure may be configured such that the energization of the liquid is stopped, the liquid helium replenishment is stopped, and the replenishment is restarted when the energization is resumed. Here, the gas-liquid sensor 14 corresponds to helium remaining amount detecting means, and the signal from the gas-liquid sensor 14 indicating that liquid helium exists near the bottom of the liquid helium storage container 2 corresponds to the helium residual signal. .

In the above, the pressurizing controller 16, the solenoid valves 8a and 8b, the heater 17, the pressurizing sensor 18, and the safety valve 19 form a pressurizing system 5, which pressurizes. It corresponds to the means.

When the pressurization controller 16 receives the above-mentioned replenishment start signal, it issues a control signal to the solenoid valves 8a and 8b to open the solenoid valve 8a and close the solenoid valve 8b, while the liquid helium is closed. A control signal is also issued to the heater 17 mounted near the bottom of the storage container 2 to start heating.

When the above operation is carried out, the liquid helium L in the liquid helium storage container 2 is vaporized and gasified by the heating of the heater 17, the gas pressure in the storage container rises, and the liquid pressure is pushed by the gas pressure and the liquid is pushed. Liquid helium L in the helium storage container 2 is transferred into the object to be cooled C through the transfer pipe 6. In this case, the pressure sensor 18 provided in the gas phase portion connected to the gas discharge port 7b of the liquid helium storage container 2 detects the gas pressure in the liquid helium storage container 2 and outputs the gas pressure signal to the pressure controller 16. The pressure controller 16 stops energizing the heater 17 when the gas pressure in the liquid helium storage container 2 rises above a predetermined pressure. The safety valve 19
This is a valve for forcibly releasing gas when the pressure is equal to or higher than the set pressure to prevent damage to the storage container and the like due to excessive pressure. In this embodiment, a mechanical valve is used.

The tip of the transfer pipe 6 on the side of the object to be cooled C is set at the time of the first injection of liquid helium L into the object to be cooled.
In order to increase the cooling efficiency, it is used such that it reaches the bottom of the object to be cooled C. Since the normal replenishment time interval of liquid helium L is much longer than the replenishment time, it is often warmed up to near room temperature even with a high degree of heat insulation. When the replenishment of liquid helium L is started in this state, the liquid helium transferred first is vaporized and becomes warm helium gas and is sent into the object to be cooled C. This warm helium gas is the object to be cooled C
When mixed in the liquid helium already stored inside,
There is also a possibility that the existing liquid helium is also vaporized and the liquid level is further lowered to make it impossible to maintain the cooling state.
Therefore, in this embodiment, after the first liquid injection is completed, the tip of the transfer pipe 6 is moved to a position higher than the minimum liquid surface level by using a driving means (not shown), and the object to be cooled of the transfer pipe 6 is further moved. The replenishment adapter 30 is attached to the tip of the C side.

The supply adapter 30, as shown in FIG.
The adapter is a plug-like adapter having a small hole-shaped opening 31 formed on the side surface and having a closed tip. When such an adapter 31 is mounted, the warmed helium gas G blown to the side of the transfer pipe 6 at the start of replenishment flows upward due to buoyancy,
It does not mix with liquid helium existing below, and does not give a large disturbance to the liquid surface of the object to be cooled C. The normally supplied two-phase helium T is separated into the helium gas G flowing upward and the liquid helium L flowing downward in the replenishment adapter 30. The height from the liquid surface of the replenishment adapter 30 at the start of the above replenishment is 5 to 30c as a result of the experiment.
No difference was observed in the range of m, there was no disturbance to the liquid helium below, and the transfer loss of liquid helium was equally good.

Next, the operation of the liquid helium replenishing device 1 will be described. First, when the liquid level of liquid helium L in the object to be cooled C falls below the minimum level, the liquid level sensor 10
The liquid level detection signal is output from the liquid level gauge 11 to the liquid level gauge 11
Outputs a liquid level signal to the liquid level monitor controller 13,
Based on this, a liquid level drop signal indicating that the liquid level of the liquid helium L in the object to be cooled C has become equal to or lower than the minimum level of the predetermined range is output from the liquid level monitoring controller 13 to the replenishment controller 15. It

On the other hand, to the replenishment controller 15, a detection signal indicating whether or not liquid helium exists near the bottom of the liquid helium storage container 2 is sent from the gas-liquid sensor 14 described above. In this case, if a detection signal indicating that liquid helium is present near the bottom of the liquid helium storage container 2 is sent, the liquid helium can be replenished, so the replenishment controller 15 causes the pressurization controller 16 to On the other hand, if a supply start signal indicating that the pressurization control should be started is output and a detection signal indicating that liquid helium does not exist near the bottom of the liquid helium storage container 2 is sent, the supply of liquid helium is replenished. Therefore, the replenishment controller 15 outputs to the pressurization controller 16 a replenishment stop signal indicating that the pressurization control should be stopped.

When the above-mentioned replenishment start signal is output, the pressurization controller 16 issues a control signal to the solenoid valves 8a and 8b,
The solenoid valve 8a is opened and the solenoid valve 8b is closed, and at the same time, the heater 17 mounted near the bottom of the liquid helium storage container 2 is also energized with a control signal to start heating. As a result, the internal pressure of the liquid helium storage container 2 increases. As a result, a pressure difference is generated at both ends of the transfer pipe 6, and the solenoid valve 8a is opened, so that the liquid helium L in the liquid helium storage container 2 is transferred to the object to be cooled C by the siphon effect.

Next, when the liquid level of the object to be cooled C reaches the maximum level, the liquid level controller 13 outputs a liquid level rising signal to the replenishment controller 15, and in response to this, the replenishment controller 15 replenishes. Output a stop signal. As a result, the pressure of the liquid helium storage container 2 drops and becomes equal to the pressure of the object to be cooled C, so that the transfer of the liquid helium L is stopped. In the above, the replenishment controller 15 corresponds to the replenishment control means, and the replenishment start signal or the replenishment stop signal corresponds to the replenishment control signal.

The present invention is not limited to the above embodiment. The above-mentioned embodiment is an exemplification, and a structure having substantially the same configuration as the technical idea described in the scope of claims for utility model registration of the present invention and having the same operational effect is as follows.
Anything is included in the technical scope of the present invention.

[0029]

As described above, according to the present invention having the above-described structure, when the liquid helium in the storage container is exhausted, the replenishment control signal for starting the replenishment is not output, so that the heated gas is cooled. The situation of sending it to an object does not occur. Therefore, there is an advantage that the reliability and safety can be improved even when the automatic operation is performed. In addition, since the means used for detecting the presence or absence of the remaining amount of liquid helium does not include moving parts immersed in liquid helium, there are problems such as freezing of moving parts in low temperature environments, wear, and clogging due to impurities. Does not occur. In addition, the use of the sensor has an advantage that it is possible to prevent the occurrence of overheating and overpressure.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a liquid helium replenishing device according to an embodiment of the present invention.

2 is a cross-sectional view showing a more detailed configuration of a gas-liquid sensor in the liquid helium replenishing device shown in FIG.

3 is a cross-sectional view showing a more detailed structure of a replenishment adapter in the liquid helium replenishing device shown in FIG.

[Explanation of symbols]

 1 Liquid Helium Replenishing Device 2 Liquid Helium Storage Container 3 Replenishing Path System 4 Sensor System 5 Pressurizing System 6 Transfer Pipes 7a, 7b Gas Release Ports 8a, 8b Solenoid Valve 9 Check Valve 10 Liquid Level Sensor 11 Liquid Level Gauge 12 Automatic Replenishment Control system 13 Liquid level monitoring controller 14 Gas-liquid sensor 15 Supply controller 16 Pressurization controller 17 Heater 18 Pressure sensor 19 Safety valve 20 Electric resistor 21 Superconducting wire 22 Current lead wire 23 Voltage terminal 30 Supply adapter 31 Open C Cover Coolant G Helium gas L Liquid helium T Two-phase helium

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Fujimoto 2-1200 Takenishi Gakuendai, Inzai-cho, Inba-gun, Chiba Hiroshi Nishiwaki, Examiner, Superconductivity Sensor Laboratory Co., Ltd. (56) Reference JP-A-64-90509 ( JP, A)

Claims (1)

(57) [Scope of utility model registration request] 1. A storage container for storing liquid helium for cooling an object to be cooled, the storage container having an on-off valve connected to a vapor phase opening, and detecting whether or not there is a remaining amount of liquid helium in the storage container. When liquid helium remains in the storage container, a helium residual amount detecting means for outputting a helium residual signal, a liquid level detecting means for detecting a liquid level of the object to be cooled and outputting a liquid level detection signal, An adiabatic transfer pipe for supplying the liquid helium from the storage container to the object to be cooled, and a replenishment control for outputting a replenishment control signal for controlling the start or end of the replenishment of the liquid helium based on the liquid level detection signal. Means for controlling the on-off valve based on the helium remaining signal and the replenishment control signal, and pressurizing means for pressurizing the gas phase part of the storage container at a predetermined pressure or less, The stage has a superconducting wire wound around an electric resistor, and the electric resistor and the superconducting wire are connected in series to form a series circuit. At the time of measurement, a direct current is passed through the series circuit, and the helium is used. When the residual amount detecting means is exposed to the outside of liquid helium and the superconducting state is broken, a voltage is generated across the superconducting wire to detect the presence or absence of the residual amount of liquid helium, and The liquid helium replenishing device, wherein the pressurizing means has a heater.