Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
2000-10-23
2002-03-05
Doerrler, William (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
Reexamination Certificate
active
06351954
ABSTRACT:
The entire disclosure of Japanese Patent Application No. Hei 11-299718 filed on Oct. 21, 1999, including the specification, drawings and abstract, is incorporated herein by reference in its entirety
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a pulse tube refrigerator and, more particularly, to a pulse tube refrigerator for cryogenic refrigeration.
1. Description of Related Art
A pulse tube refrigerator is useful as a cryogenic refrigerator. The pulse tube refrigerator refrigerates working fluid by oscillating the working fluid while shifting the phase of the pressure oscillation and displacement of the working fluid.
Various pulse tube refrigerators of this kind have been proposed, for instance by Yuan and J. M. Pfotenhauer “A single stage five valve pulse tube refrigerator reaching 32K”, in Advances in Cryogenic Engineering, Vol. 43, (1998), P.1983.
FIG. 5
is a block schematic diagram of the pulse tube refrigerator introduced in the above-mentioned publication. This pulse tube refrigerator
80
comprises a pressure oscillator
81
and a refrigerating portion
82
.
The pressure oscillator
81
generates pressure oscillation to the working fluid filled in the pulse tube refrigerator
80
and comprises a compressor
83
, a first high pressure supply on-off valve
84
, a first low pressure supply on-off valve
85
, a second high pressure supply on-off valve
86
and a second low pressure supply on-off valve
87
. An outlet port of the compressor
83
is connected to both ends (left side and right side as viewed in
FIG. 5
) of the refrigerating portion
82
via the first high pressure supply on-off valve
84
and the second high pressure supply on-off valve
86
respectively. An inlet port of the compressor source
83
is connected to both ends of the refrigerating portion
82
via the first low pressure supply on-off valve
85
and the second low pressure supply on-off valve
87
respectively. The pressure oscillator
81
generates pressure oscillations in the working fluid (gas) in the pulse tube refrigerator
80
(refrigerating portion
82
) by controlling the opening and closing of the first and second high pressure supply on-off valves
84
,
86
and the first and second low pressure supply on-off valves
85
,
87
at a predetermined timing.
The refrigerating portion
82
comprises a regenerator
91
, a low temperature heat exchanger
92
, a pulse tube
93
and a high temperature heat exchanger
94
connected in series in-line. A hot end of the regenerator
91
is connected to the pressure oscillator
81
via first high and low pressure supply valves
84
and
85
. A cold end of the regenerator
91
is connected to the low temperature heat exchanger
92
. The regenerator
91
gradually refrigerates the working fluid while the working fluid moves therethrough towards the low temperature heat exchanger
92
side and gradually heats the working fluid moving therethrough towards the pressure oscillator
81
side.
The low temperature/heat exchanger
92
connected to the cold end of the regenerator
91
generates a low temperature. In order to effectively remove the heat of a device to be refrigerated, such as an electronic device, in contact with the low temperature heat exchanger
92
, the low temperature heat exchanger
92
is provided with a number of holes regularly formed along the flow direction of the working fluid.
The pulse tube
93
connected to the low temperature heat exchanger
92
is formed by a hollow tube having a cold end
93
a
on the low temperature heat exchanger
92
side and a hot end
93
b
on the high temperature heat exchanger
94
side. The pulse tube
93
is made of a material with low heat conductivity in order to prevent the transfer of the heat generated by the oscillation from the hot end side to the low temperature heat exchanger
92
.
The high temperature heat exchanger
94
connected to the pulse tube
93
includes a number of holes regularly arranged along the flowing direction of the working fluid. The high temperature heat exchanger
94
cools the hot end side by releasing the heat of the working fluid flowing therethrough to the outside thereof. The high temperature heat exchanger
94
is connected to the second high and low pressure supply on-off valves
86
and
87
.
The pressure oscillation of the working fluid in the pulse tube
93
is generated by controlling the opening and closing of the first high and low pressure supply valves
84
and
85
at a predetermined timing. The pressure oscillation of the working fluid in the pulse tube
93
is auxiliary generated by controlling the opening and closing of the second high and low pressure supply on-off valves
86
and
87
at a predetermined timing to adjust the phase lag between the phase of the pressure oscillation and the displacement of the working fluid in the pulse tube
93
of the pulse tube refrigerator
80
. The working fluid (gas) is moved in one direction to release the heat at the high temperature heat exchanger
94
and moved in the other direction to absorb the heat at the low temperature heat exchanger
92
. The continuous repetition of this cycle generates refrigeration at the low temperature heat exchanger
92
. The operation of the pulse tube refrigerator
80
thus functions as a cryogenic refrigerator to generate refrigeration.
The above device, however, has a drawback that the operation is not stable, due to a circulation flow of working gas in a direction determined by the various operational conditions in addition to the above reciprocal movement of the flow of the working gas. This is because the conventional pulse tube refrigerator
80
forms a closed loop by the pressure oscillator
81
and the refrigerating portion
82
, one end (regenerator
91
side) of which is connected to the other side (high temperature heat exchanger
94
side) through the pressure oscillator
81
.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved pulse tube refrigerator which obviates the above conventional drawbacks.
It is another object of the present invention to provide an improved pulse tube refrigerator which is stable in operation.
According to the present invention, the above and other objects are advanced by a pulse tube refrigerator which includes a refrigerating portion including a regenerator, a low temperature heat exchanger, a pulse tube and a high temperature heat exchanger fluidically connected in this order; first pressure oscillation means for generating pressure oscillations of a working fluid in the pulse tube, said first pressure oscillation means comprising a first compressor, a first high pressure supply valve, and a first low pressure supply valve, wherein the regenerator is connected with outlet and inlet ports of the first compressor via the first high pressure supply valve and the first low pressure supply valve, respectively; and second pressure oscillation means provided independently of the first pressure oscillation means for adjusting a phase difference between the pressure oscillation and displacement of the working fluid in the pulse tube, said second pressure oscillation means having a second compression source, a second high pressure supply valve, and a second low pressure supply valve, wherein the high temperature heat exchanger is connected with outlet and inlet ports of the second compressor via the second high pressure supply valve and the second low pressure supply valve, respectively.
Since the second pressure oscillation means for adjusting the phase difference between the pressure oscillation and displacement of the working fluid is provided independently of the first pressure oscillation means, the first end second pressure oscillation means and the refrigerating portion do not form a closed loop, thereby preventing an undesired circulating flow of the working fluid and keeping the device in stable condition.
According to another aspect of the present invention, the pulse tube refrigerator further includes a buffer tank connected to the high temperature heat exchanger a
Inoue Tatsuo
Kawano Shin
Nogawa Masafumi
Zhu Shaowei
Aisin Seiki Kabushiki Kaisha
Doerrler William
Drake Malik N.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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