JP3589401B2 - Pulse tube refrigerator - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pulse tube refrigerator, and more particularly to a pulse tube refrigerator capable of adjusting a cooling temperature and a refrigeration capacity.
[0002]
[Prior art]
The pulse tube refrigerator has no moving parts in the low temperature part and has a simple structure. For this reason, it is used in many low-temperature devices as a refrigerator having less vibration. The cooling temperature or refrigeration capacity required by cryogenic equipment varies widely. Also, the required cooling temperature or refrigeration capacity may fluctuate depending on the operating conditions, time, season, and the like. In order to meet such demands, a mechanism for adjusting the cooling temperature and the refrigeration capacity is required.
[0003]
There is known a method of thermally coupling an electric heater to a cooling stage to adjust a cooling temperature and a refrigeration capacity. The excess refrigerating capacity of the pulse tube refrigerator can be offset by the heat generated from the electric heater, and the refrigerating capacity can be adjusted.
[0004]
[Problems to be solved by the invention]
The cooling stage is usually arranged in a vacuum vessel. When the electric heater breaks down, it is necessary to stop the operation of the refrigerator, raise the temperature of the low-temperature portion to room temperature, and take out the cooling stage from the vacuum vessel in order to repair the electric heater. At the start of operation, the low-temperature stage must be placed in a vacuum vessel, and the inside of the vacuum vessel must be evacuated.
[0005]
An object of the present invention is to provide a pulse tube refrigerator capable of adjusting a cooling temperature and easy to maintain.
[0006]
[Means for Solving the Problems]
According to one aspect of the present invention, a high-temperature end and a low-temperature end are defined, a regenerator having a gas flow path therein and performing heat exchange with a working gas flowing therein, and a high-temperature end and a low-temperature end are defined. , A pulse tube having an internal cavity, and a cooling stage having a gas flow path that connects low-temperature ends of the regenerator and the pulse tube to each other and communicates a gas flow path in the regenerator with an internal cavity of the pulse tube. Pressure oscillation connected to a high-temperature end of the regenerator and periodically repeating supply of a working gas to a gas passage in the regenerator and collection of a working gas from the gas passage in the regenerator source and, possess a buffer means having an interior cavity capable of changing the effective volume and a gas transport passage for communicating the interior cavity of the buffer unit and the internal cavity of said pulse tube, said buffer means But with multiple buffer tanks connected in series , The pulse tube refrigerator comprising said buffer tank at least one of which is connected to the gas transport channel, the opening and closing valve for opening and closing of the gas between adjacent buffer tank flow is provided.
[0007]
The refrigeration capacity can be changed by changing the volume of the internal cavity of the buffer means.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a schematic diagram of a pulse tube refrigerator according to a first embodiment of the present invention. A low-temperature end 1L of the regenerator 1 and a low-temperature end 2L of the pulse tube 2 are connected by a cooling stage 4. The regenerator 1 is, for example, a stainless tube filled with a regenerator material 3. The cold storage material 3 is, for example, a stainless wire mesh, and exchanges heat with the working gas flowing in the cold storage 1. The pulse tube 2 is, for example, a hollow stainless steel tube having an inner diameter of 3 to 30 mm. The cooling stage 4 is a block made of copper, and has a gas passage 5 formed therein. The gas flow path 5 connects the space in the regenerator 1 with the space in the pulse tube 2. A temperature sensor 7 is attached to the cooling stage 4.
[0009]
The regenerator 1, the pulse tube 2, and the cooling stage 4 are arranged in a vacuum vessel 6. The high-temperature end 1H of the regenerator 1 and the high-temperature end 2H of the pulse tube 2 are fixed to the wall of the vacuum vessel 6. A radiation fin is attached to the high-temperature end 2H of the pulse tube 2.
[0010]
A pressure vibration source 10 is connected to the high temperature end 1H of the regenerator 1. The pressure vibration source 10 includes a gas compressor 11 and a rotary valve 12. A gas outlet and an inlet of the gas compressor 11 are connected to a high-temperature end 1H of the regenerator 1 via a rotary valve 12. When the rotary valve 12 is rotated, a gas supply phase in which the gas discharge port of the gas compressor 11 communicates with the regenerator 1 and a gas recovery phase in which the intake port communicates with the regenerator 1 are alternately repeated.
[0011]
In the gas supply phase, a high-pressure working gas, for example, helium gas is supplied to the high-temperature end 1H of the regenerator 1. In the gas recovery phase, the working gas is recovered by the gas compressor 11 from the high temperature end 1H of the regenerator 1.
[0012]
One end of the gas transport path 21 is connected to the high temperature end 2H of the pulse tube 2. An orifice 20 having an inner diameter of 0.2 to 1 mm is arranged in the gas transport path 21. The orifice 20 acts as a flow path resistance for the working gas flowing in the gas transport path 21. Four branch paths 22a to 22d are connected to the other end of the gas transport path 21. The branch paths 22a to 22d are connected to buffer tanks 25a to 25d via on-off valves 23a to 23d, respectively. The volume of the buffer tank 25a~25d are each 100 cm ^3, 200 cm ^3, 400 cm ^3, and a 800 cm ^3. The on-off valves 23a to 23d are, for example, manual ball valves.
[0013]
The total volume of the buffer tank can be changed by opening and closing the on-off valves 23a to 23d. For example, when the on-off valve 23a is opened and the other on-off valves are closed, the total volume of the buffer tank becomes 100 cm ^{3. When the} on-off valves 23a and 23b are opened and the other on-off valves are closed, the total volume of the buffer tank is 300 cm 3. It becomes ³ . That is, the plurality of buffer tanks 25a to 25d and the on-off valves 23a to 23d effectively perform the same function as when one buffer tank with variable volume is attached.
[0014]
When the pressure vibration source 10 is operated and supply and recovery of the working gas are repeated, heat is absorbed at the low temperature end 2L of the pulse tube 2 and heat is generated at the high temperature end 2H. The heat absorption at the low temperature end 2L causes the cooling stage 4 to be cooled. The heat generated at the high temperature end 2H is radiated from the radiation fins.
[0015]
FIG. 2 shows the temperature of the cooling stage 4 when operating the pulse tube refrigerator shown in FIG. 1 as a function of the total volume of the buffer tank. The horizontal axis represents the total volume of the buffer tank in units of “cm ³ ”, and the vertical axis represents the temperature of the cooling stage in absolute temperature. The operation frequency was 2 Hz, and the pressure of the filled helium gas before the operation was 1.7 MPa.
[0016]
If the range combined volume of the buffer tank is from 100 cm ³ to 1500 cm ^3, according to the total volume is increased, the cooling stage the temperature is lowered. That is, the refrigeration capacity is improved. Thus, by changing the volume of the buffer tank, the cooling temperature and the refrigerating capacity can be adjusted.
[0017]
When operating the first pulse tube refrigerator, first, the refrigerating capacity required for the pulse tube refrigerator is determined. This can be determined from the required ultimate temperature, the amount of heat flowing into the cooling stage, and the like. Next, the capacity of the buffer tank for exhibiting the determined refrigeration capacity is determined. This can be determined, for example, from the graph shown in FIG. The on-off valves 23a to 23b are appropriately opened and closed so that the volume of the buffer tank becomes the determined volume. When the pulse tube refrigerator is operated in this state, a desired refrigeration capacity can be exhibited, and the temperature of the cooling stage 4 can be cooled to a desired temperature.
[0018]
Next, a pulse tube refrigerator according to a second embodiment will be described with reference to FIG. When comparing the pulse tube refrigerator according to the second embodiment with the pulse tube refrigerator according to the first embodiment, the connection method of the buffer tank is different mainly.
[0019]
FIG. 3 shows a schematic diagram of a pulse tube refrigerator according to the second embodiment. Here, only portions different from the configuration of the pulse tube refrigerator according to the first embodiment shown in FIG. 1 will be described. Each component of the pulse tube refrigerator shown in FIG. 3 is denoted by the same reference numeral as that of the corresponding component of the pulse tube refrigerator shown in FIG.
[0020]
The other end of the gas transport path 21 whose one end is connected to the high-temperature end 2H of the pulse tube 2 has an on-off valve 28a, a buffer tank 30a, an on-off valve 28b, a buffer tank 30b, an on-off valve 28c, and a buffer tank 30c. , The on-off valve 28d, and the buffer tank 30d are connected in series in this order. The on-off valves 28a to 28d are, for example, electromagnetic valves, and are automatically controlled based on the temperature of the cooling stage.
[0021]
The pressure vibration source 10 includes a cylinder 15 and a piston 16. A gas compression chamber defined by a cylinder 15 and a piston 16 is connected to a high temperature end 1H of the regenerator 1 via a gas flow path. By reciprocating the piston 16, supply of the working gas to the regenerator 1 and collection of the working gas from the regenerator 1 are repeated periodically. Note that, instead of the pressure vibration source 10, a rotary valve type pressure vibration source used in the first embodiment shown in FIG. 1 may be used. Conversely, a cylinder piston type gas compressor shown in FIG. 3 may be used for the pulse tube refrigerator of the first embodiment.
[0022]
The high-temperature end 1H of the regenerator 1 and the high-temperature end 2H of the pulse tube 2 are connected to each other by a gas passage, and an orifice 20a is arranged in the gas passage. By inserting the orifice 20a, the phase difference between the pressure change and the volume change of the working gas in the pulse tube 2 can be adjusted. When the phase difference is appropriately adjusted, the refrigeration efficiency can be increased.
[0023]
Also in the case of the second embodiment, the effective volume of the buffer tank can be changed by appropriately changing the open / close state of the open / close valves 28a to 28d. Further, the buffer tank and the on-off valve connected to a position farther from the pulse tube than the closed on-off valve can be maintained and inspected and replaced during operation of the refrigerator.
[0024]
FIG. 4 is a schematic view of a buffer tank used in a pulse tube refrigerator according to the third embodiment. The buffer tank includes a cylinder 35, a piston 36, and a driving device 37. A piston 36 is inserted into the cylinder 35, and a cavity 38 is defined by the cylinder 35 and the piston 36. The driving device 37 changes the insertion amount of the piston 36 and holds the piston 36 at a desired position. By changing the amount of insertion of the piston 36, the volume of the cavity 38 can be changed. A cavity 38 communicates with the internal cavity of the pulse tube via the gas transport path 21. In the case of the third embodiment, the volume of the buffer tank can be changed continuously.
[0025]
In the pulse tube refrigerator according to the above embodiment, the buffer tank and the on-off valve for adjusting the temperature of the cooling stage are arranged outside the vacuum vessel. For this reason, it is possible to prevent adverse effects on the vacuum state due to released gas, which is often seen when heating with an electric heater. In addition, maintenance work can be performed while maintaining the vacuum state of the vacuum container.
[0026]
Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.
[0027]
【The invention's effect】
As described above, according to the present invention, it is possible to adjust the cooling temperature by changing the effective volume of the buffer means connected to the high-temperature end of the pulse tube.
[Brief description of the drawings]
FIG. 1 is a schematic view of a pulse tube refrigerator according to a first embodiment of the present invention.
FIG. 2 is a graph showing the temperature of the cooling stage of the pulse tube refrigerator according to the first embodiment as a function of the effective volume of the buffer tank.
FIG. 3 is a schematic view of a pulse tube refrigerator according to a second embodiment of the present invention.
FIG. 4 is a schematic view of a buffer tank used in a pulse tube refrigerator according to a third embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 regenerator 2 pulse tube 3 regenerator material 4 cooling stage 5 gas flow path 6 vacuum vessel 7 temperature sensor 10 pressure vibration source 11 gas compressor 12 rotary valve 15 cylinder 16 piston 20, 20a orifice 21 gas transport path 22a to 22d branch path 23a to 23d, 28a to 28d Open / close valves 25a to 25d, 30a to 30d Buffer tank 35 Cylinder 36 Piston 37 Drive unit 38 Cavity

Claims (2)

A high-temperature end and a low-temperature end are defined, have a gas flow path inside, and a regenerator that exchanges heat with a working gas flowing inside,
A pulse tube having a hot end and a cold end defined and having an internal cavity;
A cooling stage having a gas passage connecting the low-temperature ends of the regenerator and the pulse tube to each other, and communicating a gas passage in the regenerator and an internal cavity of the pulse tube,
A pressure vibration source connected to the high-temperature end of the regenerator and supplying a working gas to a gas flow path in the regenerator and periodically collecting the working gas from the gas flow path in the regenerator; ,
Buffer means having an internal cavity capable of changing the effective volume;
And an internal cavity to have a gas transport passage for communicating the buffer means to the internal cavity of the pulse tube,
The buffer means is a plurality of buffer tanks connected in series, at least one of which is connected to the gas transport path, and an on-off valve that opens and closes a gas flow between adjacent buffer tanks. Including pulse tube refrigerator. 2. The pulse tube refrigerator according to claim 1, wherein the gas transport path has an orifice acting as a flow path resistance for a working gas.

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