1. Field of the Invention
The present invention relates to a pulse tube refrigerator, and in particular, to a pulse tube refrigerator which is capable of minimizing vibration occurring during the operation, and having a simple overall structure.
2. Description of the Prior Art
In general, a pulse tube refrigerator is one type of cryogenic refrigerator having a low-vibration and high-reliability which is used for cooling small size electronic parts or super-conductors. A Stirling refrigerator and a GM refrigerator are widely used as the cryogenic refrigerator.
As depicted in FIG. 1, the conventional pulse tube refrigerator comprises a compressor 10 for compressing operating gas by generating a linear reciprocation operating force, a pulse tube 20 for releasing heat on the compressing part 21 and absorbing external heat on an expanding part 22 while the operating gas is compressed and expanded at both ends of the tube by the operation of the compressor 10, an inertance tube 30 for generating phase difference between mass flow and pressure pulsation of the operating gas fluctuated by connecting to the pulse tube 20 and at the same time achieving the heat balance, a reservoir 40 connected to the end of the inertance tube 30, a regenerating unit 50 connected between the pulse tube 20 and after-cooler 60 in order to store and release sensible heat of the operating gas passing the pulse tube 20 by being sucked and compressed at the compressor 10, and an after-cooler 60 placed between the regenerating unit 50 and compressor 10 for cooling the operating gas pushed by the compressor 10 before it reaches the regenerating unit 50.
The compressor 10 for compressing and sucking the operating gas while generating the linear reciprocation operating force comprises a sealed casing 11 having the inner area covering housings 11b, 11c, an upper housing 11a closely combined to the upper outer circumference of the sealed casing 11 having a cylinder unit on the center portion, a middle housing 11b which is placed inside of the sealed casing 11 and its upper surface is closely combined to the lower surface of the upper housing 11a, an elastic supporting member 15 is combined inside of it, an operating motor 12 having a piston 14 inserted into the cylinder unit 13 is fixedly installed on it, and a lower housing 11c which is placed inside of the sealed casing 11 and its upper surface is closely combined to the lower surface of the middle housing 11b, the elastic supporting member 15 is combined to it.
The operation of the conventional pulse tube refrigerator will now be described.
First, when the compressor 10 compresses and sucks the operating gas by being applied power, the operating gas flows into the pulse tube 20 after passing the after-cooler 60 and regenerating unit 50, is discharged into the inertance tube 30, repeats the reverse operation, while repeating the above operation, the phase difference is generated between the mass flow and pressure pulsation, according to this the compressing and expanding occur at the compressing part 21 and expanding part 22 of the pulse tube 20, temperature on the expanding part 22 of the pulse tube 20 lowers drastically.
The inertance tube 30 and reservoir 40 accelerate the compressing and expanding of the operating gas at the pulse tube 20, the after-cooler pre-cools the operating gas pushed from the compressor 10, and the regenerating unit 50 stores/releases the sensible heat of the operating gas reciprocating between the compressor 10 and pulse tube 20.
While repeating the above-mentioned process, the expanding part 22 of the pulse tube 20 is cooled continually, and accordingly the cryogenic refrigeration is obtained.
However, in the conventional pulse tube refrigerator, vibration occurs while the operating gas is compressed by the piston receiving the linear reciprocating motion of the operating motor installed in the compressor, and it causes the vibration noise.
In addition, because the reservoir constructed as the additional part is connected to the inertance tube having a certain length, the overall size of the pulse tube refrigerator is big, lots of manufacturing costs are required, it is difficult to transfer, and it requires lots of installation area.
The object of the present invention is to provide a pulse tube refrigerator which has a simple overall structure.
Another object of the present invention is to provide the pulse tube refrigerator having a vibration absorbing unit which efficiently reduces vibration occurring while compressing operating gas.
Another object of the present invention is to provide the pulse tube refrigerator having a combining structure of a sealing member which improves the efficiency of the vibration absorbing unit.
In order to achieve the objects, the pulse tube refrigerator according to the present invention comprises a compressor having a sealed casing with a cylinder and an opening at one end thereof, a motor mounted in the sealed casing, and a piston operatively attached with the motor to compress and expand an operating gas via the opening, an after-cooler connected with the compressor in order to cool the operating gas discharged from the compressor, a regenerating unit connected with the after-cooler in order to store and release latent heat of the operating gas reciprocating between the compressor and reservoir formed at an outer surface of the sealed casing and a cover integrally attached to the sealed casing, a pulse tube connected with the regenerating unit, the pulse tube having a cryogenic portion formed thereon, an inertance tube connected with the pulse tube in order to accelerate a formation of the cryogenic portion and connected with the cover, and a vibration absorbing unit which is placed inside of the reservoir and is fixedly attached to the sealed casing in order to reduce the vibration occurring due to the operation of the motor.
In addition, in order to achieve the above-mentioned objects, the pulse tube refrigerator according to the present invention comprises a compressor having a sealed casing with a cylinder and an opening at one end thereof, a motor mounted in the sealed casing, and a piston operatively attached with the motor to compress and expand an operating gas via the opening, an after-cooler connected with the compressor in order to cool the operating gas discharged from the compressor, a regenerating unit connected with the after-cooler in order to store and release latent heat of the operating gas reciprocating between the compressor and a reservoir formed at an outer surface of the sealed casing a a cover attached to the sealed casing, a pulse tube connected with the regenerating unit, the pulse tube having a cryogenic portion formed thereon, an inertance tube connected with the pulse tube in order to accelerate a formation of the cryogenic portion and connected with the cover, a sealing member which is placed between the cover and casing in order to prevent leakage of the operating gas, and a vibration absorbing unit placed inside of the reservoir and fixedly attached to the sealing member in order to reduce the vibration occurring due to the operation of the motor.