Pulse tube refrigerator

Details Pulse tube refrigerator Pulse tube refrigerator

1999-05-27

2001-03-06

Capossela, Ronald (Department: 3744)

Refrigeration

Gas compression, heat regeneration and expansion, e.g.,...

C060S520000

Reexamination Certificate

active

06196006

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a pulse tube refrigerator and in particular to a pulse tube refrigerator for cooling a specific device below a temperature, which can be connected thereto in easier manner and with improved refrigerating efficiency.
2. Discussion of the Background
A conventional pulse tube refrigerator is disclosed in U.S. Pat. No. 5,515,685. Similar pulse regenerators are also disclosed in U.S. Pat. No. 5,522,223 and U.S. Pat. No. 5,335,505.
The conventional pulse tube refrigerator includes a pulse tube and a regenerator arranged in parallel thereto in such a manner that lower temperature ends of the pulse tube and the regenerator are in fluid communication with each other. The lower temperature ends of the pulse tube and the regenerator are mounted with a common cold head. The cold head is brought into contact with a member for cooling the same to a determined temperature in such a manner that coldness or an ultra low temperature generated at the lower temperature end of the pulse tube is transferred via the cold head to the member.
In the foregoing structure, a high or higher temperature end and a lower temperature end of each of the pulse tube and the regenerator, both of which extend in the downward direction, take higher and lower position, respectively. This means that the contact of the cold head with the member is established from the top thereof.
On the other hand, it is required to contact the cold head of the pulse tube refrigerator with the member to be cooled down from the bottom or a horizontal side thereof. In order to comply with such a need, it has been considered to establish such a connection after inverting the device or tipping the device down.
However, such an idea is not acceptable from a practical viewpoint. In detail, inverting the pulse tube refrigerator produces a higher position of the lower temperature end of the pulse tube and a lower position of the higher temperature end of the pulse tube, resulting in an occurrence of free convection of the working gas in the pulse tube. This free convection causes a movement of a higher temperature fluid at the higher temperature end to the lower temperature end and therefore such a heat movement acts as a heat load on the cold head. Thus, the resultant heat load on the cold head drops the refrigerating efficiency of the pulse tube refrigerator. Tipping the pulse tube refrigerator down makes a horizontal extension of the pulse tube. In the resultant condition, a temperature distribution of the working gas is disturbed in the pulse tube which disturbs a designed speed of the working gas in the pulse tube, resulting in that the refrigerating efficiency of the pulse tube refrigerator drops inevitably.
SUMMARY OF THE INVENTION
Therefore, in view of the foregoing circumstances, the present invention is intended to provide a pulse tube refrigerator which can be connected to a specific member to be cooled from any side without dropping the refrigerating efficiency.
In order to attain the foregoing objects, a pulse tube refrigerator includes a supporting member having an upper side and a lower side, respectively; a pulse tube having at opposite ends thereof a first higher temperature end connected to the lower side of the higher temperature end and a first lower temperature end, respectively; a regenerator having at opposite ends thereof a second temperature end connected to the upper side of the supporting member and a second lower temperature end; a connecting pipe connected between the first lower temperature end of the pulse tube and the second higher temperature end of the regenerator; a pressure oscillation device oscillating a working gas filled in a system between the pulse tube and the regenerator; a phase difference controller controlling a phase difference between a pressure oscillation and a displacement of the working gas; and a cold head disposed at one of the first higher temperature end of the pulse tube and the second lower temperature end of the regenerator.


REFERENCES:
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patent: 5904046 (1999-05-01), Kawano
patent: 5974807 (1999-11-01), Gao et al.

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