U.S. patent application number 10/550526 was filed with the patent office on 2007-01-04 for pulse tube refrigerating machine.
This patent application is currently assigned to Aisin Seiki Kabushiki Kaisha. Invention is credited to Motohiro Igarasi, Katsuyuki Kuwano, Hideo Mita, Takeshi Okutomi, Toyohisa Yamada.
Application Number | 20070000257 10/550526 |
Document ID | / |
Family ID | 33095035 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070000257 |
Kind Code |
A1 |
Mita; Hideo ; et
al. |
January 4, 2007 |
Pulse tube refrigerating machine
Abstract
To provide a pulse tube refrigerator for enhancing refrigeration
capacity. A pulse tube refrigerator includes a pressure-waveform
generating device 1 for generating a pressure waveform of
refrigerant gas, pulse tubes 14, 20 into which refrigerant gas with
pressure waveforms flow, one of whose ends is adapted to a
low-temperature end, and the other one of whose ends is adapted to
a high-temperature end, cold accumulators 8, 10 for pre-cooling the
refrigerant gas to be flowed into the pulse tubes 14, 20, a
pressure-waveform phase controlling element having a buffer tank 23
communicating with the high-temperature end of the pulse tube 20,
and controlling a pressure-waveform phase of the refrigerant gas
for generating refrigeration at the low-temperature end of the
pulse tube 20, and a vacuum heat-insulation bath 24 having a vacuum
heat-insulation chamber 24w for accommodating the pulse tube 20.
The buffer tank 23 is placed within the vacuum heat-insulation
chamber 24w of the vacuum heat-insulation bath 24.
Inventors: |
Mita; Hideo; (Aichi-ken,
JP) ; Yamada; Toyohisa; (Aichi-ken, JP) ;
Igarasi; Motohiro; (Aichi-ken, JP) ; Okutomi;
Takeshi; (Aichi-ken, JP) ; Kuwano; Katsuyuki;
(Aichi-ken, JP) |
Correspondence
Address: |
C. IRVIN MCCLELLAND;OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Aisin Seiki Kabushiki
Kaisha
1, Asahi-machi 2-chome
Kariya-shi
JP
448-8650
Central Japan Railway Company
1-14, Meieki, Nakamura-ku
Nagoya-shi
JP
450-6101
|
Family ID: |
33095035 |
Appl. No.: |
10/550526 |
Filed: |
March 25, 2004 |
PCT Filed: |
March 25, 2004 |
PCT NO: |
PCT/JP04/04226 |
371 Date: |
July 10, 2006 |
Current U.S.
Class: |
62/6 |
Current CPC
Class: |
F25B 2309/1418 20130101;
F25B 2309/1423 20130101; F25B 9/145 20130101; F25B 2309/1417
20130101; F25D 19/006 20130101; F25B 2309/1412 20130101; F25B
2309/1408 20130101; F25B 9/10 20130101 |
Class at
Publication: |
062/006 |
International
Class: |
F25B 9/00 20060101
F25B009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2003 |
JP |
2003-085650 |
Claims
1. A pulse tube refrigerator, comprising: a pressure-waveform
generating device for generating a pressure waveform of refrigerant
gas; a pulse tube into which refrigerant gas with the pressure
waveform generated by said pressure-waveform generating device
flows, one of whose ends is adapted to a low-temperature end, and
the other one of whose ends is adapted to a high-temperature end; a
cold accumulator disposed between said pressure-waveform generating
device and said pulse tube, and pre-cooling the refrigerant gas to
be flowed into said pulse tube; a pressure-waveform phase
controlling element having a buffer tank communicating with the
high-temperature end of said pulse tube, and controlling a
pressure-waveform phase of the refrigerant gas for generating
refrigeration at the low-temperature end of said pulse tube; and a
vacuum heat-insulation bath having a vacuum heat-insulation chamber
for accommodating said pulse tube, wherein the pulse tube
refrigerator is characterized in that said buffer tank is placed
within said vacuum heat-insulation chamber of said vacuum
heat-insulation bath.
2. A pulse tube refrigerator, comprising: a pressure-waveform
generating device for generating a pressure waveform of refrigerant
gas; a pulse tube into which refrigerant gas with the pressure
waveform generated by said pressure-waveform generating device
flows, one of whose ends is adapted to a low-temperature end, and
the other one of whose ends is adapted to a high-temperature end; a
cold accumulator disposed between said pressure waveform generating
device and said pulse tube, and pre-cooling the refrigerant gas to
be flowed into said pulse tube; a pressure-waveform phase
controlling element having an inertance tube communicating with the
high-temperature end of said pulse tube and having a flow passage
with a smaller inside diameter than an inside diameter of said
pulse tube, a buffer tank communicating with the high-temperature
end of said pulse tube by way of said inertance tube, and
controlling a pressure-waveform phase of the refrigerant gas for
generating refrigeration at the low-temperature end of said pulse
tube; and a vacuum heat-insulation bath having a vacuum
heat-insulation chamber for accommodating said pulse tube, wherein
the pulse tube refrigerator is characterized in that said inertance
tube is placed within said vacuum heat-insulation chamber of said
vacuum heat-insulation bath.
3. A pulse tube refrigerator, comprising: a pressure-waveform
generating device for generating a pressure waveform of refrigerant
gas; a first pulse tube into which refrigerant gas with the
pressure waveform generated by said pressure-waveform generating
device flows, one of whose ends is adapted to a low-temperature
end, and the other one of whose ends is adapted to a
high-temperature end; a second pulse tube into which refrigerant
gas with a pressure waveform flows, one of whose ends is adapted to
a low-temperature end, the low-temperature end becoming a lower
temperature than the low-temperature end of said first pulse tube,
and the other one of whose ends is adapted to a high-temperature
end; a cold accumulator disposed between said pressure-waveform
generating device, said first pulse tube and said second pulse
tube, and pre-cooling the refrigerant gas to be flowed into said
first pulse tube and/or said second pulse tube; a pressure-waveform
phase controlling element having a first inertance tube
communicating with the high-temperature end of said first pulse
tube and having a flow passage with a smaller inside diameter than
an inside diameter of said first pulse tube, a first buffer tank
communicating with the high-temperature end of said first pulse
tube by way of said first inertance tube, a second inertance tube
communicating with the high-temperature end of said second pulse
tube and having a flow passage with a smaller inside diameter than
an inside diameter of said second pulse tube, and a second buffer
tank communicating with the high-temperature end of said second
pulse tube by way of said second inertance tube, and controlling
pressure-waveform phases of the refrigerant gas for generating
refrigeration; and a vacuum heat-insulation bath having a vacuum
heat-insulation chamber for accommodating said second pulse tube at
least, wherein a cooling element contacting thermally with the
low-temperature end of said first pulse tube and being cooled by
refrigeration from the low-temperature end of said first pulse tube
is disposed, and said cooling element is brought into contact with
said second inertance tube thermally.
4. A pulse tube refrigerator, comprising: a pressure-waveform
generating device for generating a pressure waveform of refrigerant
gas; a first pulse tube into which refrigerant gas with the
pressure waveform generated by said pressure-waveform generating
device flows, one of whose ends is adapted to a low-temperature
end, and the other one of whose ends is adapted to a
high-temperature end; a second pulse tube into which refrigerant
gas with a pressure waveform flows, one of whose ends is adapted to
a low-temperature end, the low-temperature end becoming a lower
temperature than the low-temperature end of said first pulse tube,
and the other one of whose ends is adapted to a high-temperature
end; a cold accumulator disposed between said pressure-waveform
generating device, said first pulse tube and said second pulse
tube, and pre-cooling the refrigerant gas to be flowed into said
first pulse tube and/or said second pulse tube; a pressure-waveform
phase controlling element having a first inertance tube
communicating with the high-temperature end of said first pulse
tube and having a flow passage with a smaller inside diameter than
an inside diameter of said first pulse tube, a first buffer tank
communicating with the high-temperature end of said first pulse
tube by way of said first inertance tube, a second inertance tube
communicating with the high-temperature end of said second pulse
tube and having a flow passage with a smaller inside diameter than
an inside diameter of said second pulse tube, and a second buffer
tank communicating with the high-temperature end of said second
pulse tube by way of said second inertance tube, and controlling
pressure-waveform phases of the refrigerant gas for generating
refrigeration; and a vacuum heat-insulation bath having a vacuum
heat-insulation chamber for accommodating said second pulse tube at
least, wherein a cooling element contacting thermally with the
low-temperature end of said first pulse tube and being cooled by
refrigeration from the low-temperature end of said first pulse tube
is disposed, and said cooling element is brought into contact with
said second buffer tank thermally.
5. A pulse tube refrigerator, comprising: a pressure-waveform
generating device for generating a pressure waveform of refrigerant
gas; a first pulse tube into which refrigerant gas with the
pressure waveform generated by said pressure-waveform generating
device flows, one of whose ends is adapted to a low-temperature
end, and the other one of whose ends is adapted to a
high-temperature end; a second pulse tube into which refrigerant
gas with a pressure waveform flows, one of whose ends is adapted to
a low-temperature end, the low-temperature end becoming a lower
temperature than the low-temperature end of said first pulse tube,
and the other one of whose ends is adapted to a high-temperature
end; a cold accumulator disposed between said pressure-waveform
generating device, said first pulse tube and said second pulse
tube, and pre-cooling the refrigerant gas to be flowed into said
first pulse tube and said second pulse tube; a pressure-waveform
phase controlling element having a first inertance tube
communicating with the high-temperature end of said first pulse
tube and having a flow passage with a smaller inside diameter than
an inside diameter of said first pulse tube, a first buffer tank
communicating with the high-temperature end of said first pulse
tube by way of said first inertance tube, a second inertance tube
communicating with the high-temperature end of said second pulse
tube and having a flow passage with a smaller inside diameter than
an inside diameter of said second pulse tube, and a second buffer
tank communicating with the high-temperature end of said second
pulse tube by way of said second inertance tube, and controlling
pressure-waveform phases of the refrigerant gas for generating
refrigeration; and a vacuum heat-insulation bath having a vacuum
heat-insulation chamber for accommodating said second pulse tube at
least, wherein at least a part of said second inertance tube is
brought into contact with the low-temperature end of said first
pulse tube thermally.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pulse tube refrigerator
for generating ultracold temperatures.
BACKGROUND ART
[0002] As a prior art, a pulse tube refrigerator illustrated in
FIG. 8 (Patent Literature No. 1: Japanese Unexamined Patent
Publication (KOKAI) No. 9-296,963) has been known. This pulse tube
refrigerator has a compressor 121, low-pressure supply valves 122,
124, 126, high-pressure supply valves 123, 125, 127, a first pulse
tube 107, a second pulse tube 117, a first cold accumulator 103,
and a second cold accumulator 13, as shown in FIG. 8. The first
pulse tube 107 has a high-temperature end 107H, and a
low-temperature end 107L. The second pulse tube 117, which is on a
much lower temperature side, has a high-temperature end 117H, and a
low-temperature end 117L.
[0003] In accordance with this pulse tube refrigerator, the
high-temperature end 117H of the second pulse tube 117 is disposed
in a room-temperature portion, and is cooled by air. Accordingly,
since the volume of the second pulse tube 117 becomes large, there
is a limitation on enhancing the compression ratio of refrigerant
gas within a cooling circuit, consequently, there has been a
limitation on enhancing the cooling capacity generating at a lower
end, which is one of the opposite-end sides of the second pulse
tube 117.
[0004] Moreover, in accordance with this pulse tube refrigerator, a
warm gas, which is a room temperature or more, flows into the
low-temperature end of the second pulse tube 117 from the
high-temperature end 117H of the second pulse tube 117, there has
been a limitation on enhancing the cooling capacity generating at
the low-temperature end 117L of the second pulse tube 117, in this
sense as well.
[0005] Moreover, as a prior art, there is a pulse tube refrigerator
disclosed in a literature (Non-patent literature No. 1:
Cryocoolers, 11, P189-198 Design and Test of the NIST/Lockeed
Martin Minituature Pulse Tube Fligt Cryosooler) illustrated in FIG.
9. This pulse tube refrigerator has a compressor 209, a first pulse
tube 201, a second pulse tube 203, a first cold accumulator 207, a
second cold accumulator 206, and orifices 300, 301, 302, as shown
in FIG. 9. The first pulse tube 201 has a high-temperature end
201H, and a low-temperature end 201L. The second pulse tube 203,
which is on a much lower temperature side, has a high-temperature
end 203H, and a low-temperature end 203L.
[0006] In accordance with this pulse tube refrigerator, the
high-temperature end 203H of the second pulse tube 203 is disposed
to be connected with the low-temperature end 201L of the first
pulse tube 201. Accordingly, the high-temperature end 203H of the
second pulse tube 203 is cooled by refrigeration generating at the
first pulse tube 201, but, since the high-temperature end 203H of
the second pulse tube 203 is simply disposed on the low-temperature
end 201L of the first pulse tube 201, no favorable cooling capacity
can be obtained at the low-temperature end 203L of the second pulse
tube 203, even if the gas compression ratio of refrigerant gas is
large.
[0007] (Patent Literature No. 1: Japanese Unexamined Patent
Publication (KOKAI) No. 9-296,963)
[0008] (Non-patent literature No. 1: Cryocoolers, 11, P189-198
Design and Test of the NIST/Lockeed Martin Minituature Pulse Tube
Fligt Cryosooler)
DISCLOSURE OF THE INVENTION
[0009] The present invention is done in view of the aforementioned
circumstances, and provides a pulse tube refrigerator which is
advantageous for enhancing the cooling capacity.
[0010] (1) A first aspect of a pulse tube refrigerator of the
present invention comprises: a pressure-waveform generating device
for generating a pressure waveform of refrigerant gas;
[0011] a pulse tube into which refrigerant gas with the pressure
waveform generated by the pressure-waveform generating device
flows, one of whose ends is adapted to a low-temperature end, and
the other one of whose ends is adapted to a high-temperature
end;
[0012] a cold accumulator disposed between the pressure-waveform
generating device and the pulse tube, and pre-cooling the
refrigerant gas to be flowed into the pulse tube;
[0013] a pressure-waveform phase controlling element having a
buffer tank communicating with the high-temperature end of the
pulse tube, and controlling a pressure-waveform phase of the
refrigerant gas for generating refrigeration at the low-temperature
end of the pulse tube; and
[0014] a vacuum heat-insulation bath having a vacuum
heat-insulation chamber for accommodating the pulse tube,
[0015] wherein the pulse tube refrigerator is characterized in that
the buffer tank is placed within the vacuum heat-insulation chamber
of the vacuum heat-insulation bath.
[0016] In accordance with the first aspect of the pulse tube
refrigerator of the present invention, the buffer tank is placed
within the vacuum heat-insulation chamber of the vacuum
heat-insulation bath, along with the pulse tube. Accordingly, the
heat of air is inhibited from entering the buffer tank. Therefore,
it is possible to maintain the refrigerant gas within the buffer
tank at a low temperature. Consequently, it is possible to enhance
the compression ratio of the refrigerant gas within a cooling
circuit, the refrigeration amount generated at the
lower-temperature end of the pulse tube becomes large, and it
becomes advantageous for enhancing the cooling capacity of the
pulse tube refrigerator.
[0017] In accordance with the first aspect of the pulse tube
refrigerator of the present invention, when a first buffer tank and
a second buffer tank are disposed, it is possible to place the
second buffer tank, which is on a low-temperature side, within the
vacuum heat-insulation bath.
[0018] Note that, in accordance with the respective aspects of the
present invention, the pressure-waveform generating device
generates a pressure waveform of refrigerant gas, and can be formed
using compressors, for example. The cold accumulator is disposed
between the pressure-waveform generating device and the pulse tube,
and has a function of cooling the refrigerant gas to be flowed into
the pulse tube. The cold accumulator can be formed using materials,
such as metals, whose heat capacities are large.
[0019] In accordance with the respective aspects of the present
invention in the preset description, the inside of the vacuum
heat-insulation chamber of the vacuum heat-insulation bath is
maintained in a high-vacuum state, and can intend to obtain vacuum
heat insulation. In this instance, as for the high-vacuum state, it
is possible to exemplify 10.sup.-3 Torr or less
(.apprxeq.133.times.10.sup.-3 Pa or less), more preferably, it is
possible to exemplify 10.sup.-4 Torr or less
(.apprxeq.133.times.10.sup.-4 Pa or less)
[0020] (2) A second aspect of a pulse tube refrigerator of the
present invention comprises: a pressure-waveform generating device
for generating a pressure waveform of refrigerant gas;
[0021] a pulse tube into which refrigerant gas with the pressure
waveform generated by the pressure-waveform generating device
flows, one of whose ends is adapted to a low-temperature end, and
the other one of whose ends is adapted to a high-temperature
end;
[0022] a cold accumulator disposed between the pressure waveform
generating device and the pulse tube, and pre-cooling the
refrigerant gas to be flowed into the pulse tube;
[0023] a pressure-waveform phase controlling element having an
inertance tube communicating with the high-temperature end of the
pulse tube and having a flow passage with a smaller inside diameter
than an inside diameter of the pulse tube, a buffer tank
communicating with the high-temperature end of the pulse tube by
way of the inertance tube, and controlling a pressure-waveform
phase of the refrigerant gas for generating refrigeration at the
low-temperature end of the pulse tube; and
[0024] a vacuum heat-insulation bath having a vacuum
heat-insulation chamber for accommodating the pulse tube,
[0025] wherein the pulse tube refrigerator is characterized in that
the inertance tube is placed within the vacuum heat-insulation
chamber of the vacuum heat-insulation bath.
[0026] In accordance with the second aspect of the pulse tube
refrigerator of the present invention, the refrigerant gas at the
high-temperature end of the pulse tube flows in and flows out with
respect to the buffer tank by way of the inertance tube, which has
a flow passage with a smaller inside diameter than an inside
diameter of the pulse tube. At this moment, a pressure-waveform
phase of the refrigerant gas is adjusted so that refrigeration at
the low-temperature end of the pulse tube is generated favorably.
The inertance tube functions as the pressure-waveform phase
controlling element for adjusting the phase and pressure amplitude
of the refrigerant gas, together with the buffer tank. In the
viewpoint of having the function of adjusting the pressure-waveform
phase of the refrigerant gas, the inertance tube plays a function
of inductance in electric circuit (a function of generating a phase
difference of the refrigerant gas), when considering its
correspondence to electric circuit.
[0027] In accordance with the second aspect of the pulse tube
refrigerator of the present invention, the inertance tube is placed
within the vacuum heat-insulation chamber of the vacuum
heat-insulation bath, along with the pulse tube. Accordingly, the
heat of air is inhibited from entering the inertance tube.
Therefore, it is possible to maintain the refrigerant gas flowing
in the inertance tube at a low temperature. Consequently, it is
possible to enhance the compression ratio of the refrigerant gas
within a cooling circuit, the refrigeration amount generated at the
lower-temperature end of the pulse tube becomes large, and it
becomes advantageous for enhancing the cooling capacity of the
pulse tube refrigerator.
[0028] Especially, when the refrigerant gas, which flows in the
inertance tube, is a low temperature, a flow-passage resistance of
the inertance tube becomes smaller, and it is possible to make a
viscosity loss of the gas, which flows within the inertance tube,
small. As a result, since it is possible to make a phase and gas
amount of the refrigerant gas, which flows into the
high-temperature end of the pulse tube, favorable, the cooling
capacity enlarges.
[0029] In accordance with the second aspect of the pulse tube
refrigerator of the present invention, when a first inertance tube
communicating with a first buffer tank, and a second inertance tube
communicating with a second buffer tank are disposed, it is
possible to place the second inertance tube, which is on a
low-temperature side, within the vacuum heat-insulation bath.
[0030] (3) A third aspect of a pulse tube refrigerator of the
present invention comprises: a pressure-waveform generating device
for generating a pressure waveform of refrigerant gas;
[0031] a first pulse tube into which refrigerant gas with the
pressure waveform generated by the pressure-waveform generating
device flows, one of whose ends is adapted to a low-temperature
end, and the other one of whose ends is adapted to a
high-temperature end;
[0032] a second pulse tube into which refrigerant gas with a
pressure waveform flows, one of whose ends is adapted to a
low-temperature end, the low-temperature end becoming a lower
temperature than the low-temperature end of the first pulse tube,
and the other one of whose ends is adapted to a high-temperature
end;
[0033] a cold accumulator disposed between the pressure-waveform
generating device, the first pulse tube and the second pulse tube,
and pre-cooling the refrigerant gas to be flowed into the first
pulse tube and/or the second pulse tube;
[0034] a pressure-waveform phase controlling element having a first
inertance tube communicating with the high-temperature end of the
first pulse tube and having a flow passage with a smaller inside
diameter than an inside diameter of the first pulse tube, a first
buffer tank communicating with the high-temperature end of the
first pulse tube by way of the first inertance tube, a second
inertance tube communicating with the high-temperature end of the
second pulse tube and having a flow passage with a smaller inside
diameter than an inside diameter of the second pulse tube, and a
second buffer tank communicating with the high-temperature end of
the second pulse tube by way of the second inertance tube, and
controlling pressure-waveform phases of the refrigerant gas for
generating refrigeration; and
[0035] a vacuum heat-insulation bath having a vacuum
heat-insulation chamber for accommodating the second pulse tube at
least,
[0036] wherein a cooling element contacting thermally with the
low-temperature end of the first pulse tube and being cooled by
refrigeration from the low-temperature end of the first pulse tube
is disposed, and the cooling element is brought into contact with
the second inertance tube thermally.
[0037] In accordance with the third aspect of the pulse tube
refrigerator of the present invention, the refrigerant gas at the
high-temperature ends of the pulse tubes flows in and flows out
with respect to the buffer tanks by way of the inertance tubes,
which have flow passages with smaller inside diameters than inside
diameters of the pulse tubes. At this moment, pressure-waveform
phases of the refrigerant gas are adjusted so that refrigeration at
the low-temperature ends of the pulse tubes is generated favorably.
The inertance tubes function as the pressure-waveform phase
controlling element for adjusting the phases and pressure
amplitudes of the refrigerant gas, together with the buffer tanks.
In the viewpoint of having the function of adjusting the
pressure-waveform phases of the refrigerant gas, the inertance
tubes play a function of inductance in electric circuit, when
considering their correspondence to electric circuit.
[0038] Further, the cooling element, which contacts with the
low-temperature end of the first pulse tube and is cooled by
refrigeration from the low-temperature end of the first pulse tube,
is disposed. Accordingly, the cooling element is cooled by
refrigeration at the low-temperature end of the first pulse
tube.
[0039] Further, in accordance with the third aspect of the pulse
tube refrigerator of the present invention, since the cooling
element is brought into contact with the second inertance tube
thermally, the second inertance tube is cooled by refrigeration
from the low-temperature end of the first pulse tube. Accordingly,
it is possible to maintain the refrigerant gas, which flows in the
inertance tube, at a low temperature. Therefore, it is possible to
enhance the compression ratio of the refrigerant gas within a
cooling circuit, the refrigeration amount generated at the
lower-temperature end of the pulse tube becomes large, and it
becomes advantageous for enhancing the cooling capacity of the
pulse tube refrigerator.
[0040] Especially, when the refrigerant gas, which flows in the
inertance tubes are low temperatures, flow-passage resistances of
the inertance tubes become smaller, and it is possible to make
viscosity losses of the gas, which flows within the inertance
tubes, small, as a result, since it is possible to make phases and
gas amounts of the refrigerant gas, which flows into the
high-temperature ends of the pulse tubes, favorable, the cooling
capacity enlarges.
[0041] As for the cooling element, it can preferably be formed of
metals of favorable heat transferability. As for the cooling
element, it is possible to exemplify plates. The shapes of plates
are not limited in particular. In order to enhance the cooling
ability with respect to the inertance tube, it is possible to
enlarge a thermally contacting area between the cooling element and
the inertance tube.
[0042] (4) A fourth aspect of a pulse tube refrigerator of the
present invention comprises: a pressure-waveform generating device
for generating a pressure waveform of refrigerant gas;
[0043] a first pulse tube into which refrigerant gas with the
pressure waveform generated by the pressure-waveform generating
device flows, one of whose ends is adapted to a low-temperature
end, and the other one of whose ends is adapted to a
high-temperature end;
[0044] a second pulse tube into which refrigerant gas with a
pressure waveform flows, one of whose ends is adapted to a
low-temperature end, the low-temperature end becoming a lower
temperature than the low-temperature end of the first pulse tube,
and the other one of whose ends is adapted to a high-temperature
end;
[0045] a cold accumulator disposed between the pressure-waveform
generating device, the first pulse tube and the second pulse tube,
and pre-cooling the refrigerant gas to be flowed into the first
pulse tube and/or the second pulse tube;
[0046] a pressure-waveform phase controlling element having a first
inertance tube communicating with the high-temperature end of the
first pulse tube and having a flow passage with a smaller inside
diameter than an inside diameter of the first pulse tube, a first
buffer tank communicating with the high-temperature end of the
first pulse tube by way of the first inertance tube, a second
inertance tube communicating with the high-temperature end of the
second pulse tube and having a flow passage with a smaller inside
diameter than an inside diameter of the second pulse tube, and a
second buffer tank communicating with the high-temperature end of
the second pulse tube by way of the second inertance tube, and
controlling pressure-waveform phases of the refrigerant gas for
generating refrigeration; and
[0047] a vacuum heat-insulation bath having a vacuum
heat-insulation chamber for accommodating the second pulse tube at
least,
[0048] wherein a cooling element contacting thermally with the
low-temperature end of the first pulse tube and being cooled by
refrigeration from the low-temperature end of the first pulse tube
is disposed, and the cooling element is brought into contact with
the second buffer tank thermally.
[0049] In accordance with the fourth aspect of the pulse tube
refrigerator of the present invention, the cooling element, which
contacts with the low-temperature end of the first pulse tube and
is cooled by refrigeration from the low-temperature end of the
first pulse tube, is disposed. Accordingly, the cooling element is
cooled by refrigeration at the low-temperature end of the first
pulse tube.
[0050] Further, in accordance with the fourth aspect of the pulse
tube refrigerator of the present invention, since the cooling
element is brought into contact with the second buffer tank
thermally, the second buffer tank is cooled by refrigeration from
the low-temperature end of the first pulse tube. Accordingly, it is
possible to maintain the refrigerant gas within the second buffer
tank at a low temperature. Therefore, it is possible to enhance the
compression ratio of the refrigerant gas within a cooling circuit,
the refrigeration amount generated at the lower-temperature end of
the pulse tube becomes large, and it becomes advantageous for
enhancing the cooling capacity of the pulse tube refrigerator.
[0051] The cooling element contacts thermally with the
low-temperature end of the first pulse tube and is cooled by
refrigeration from the low-temperature end of the first pulse tube.
As for the cooling element, it can preferably be formed of metals
of good heat transferability (aluminum alloys, copper alloys, iron
alloys, and the like, in general). As for shapes of the cooling
element, they are not limited in particular, but it is possible to
exemplify plate shapes. The shapes of plates are not limited in
particular. In order to enhance the cooling ability with respect to
the second buffer tank, as for a thermally contacting area between
the cooling element and the second buffer tank, it can be
enlarged.
[0052] (5) A fourth aspect of a pulse tube refrigerator of the
present invention comprises: a pressure-waveform generating device
for generating a pressure waveform of refrigerant gas;
[0053] a first pulse tube into which refrigerant gas with the
pressure waveform generated by the pressure-waveform generating
device flows, one of whose ends is adapted to a low-temperature
end, and the other one of whose ends is adapted to a
high-temperature end;
[0054] a second pulse tube into which refrigerant gas with a
pressure waveform flows, one of whose ends is adapted to a
low-temperature end, the low-temperature end becoming a lower
temperature than the low-temperature end of the first pulse tube,
and the other one of whose ends is adapted to a high-temperature
end;
[0055] a cold accumulator disposed between the pressure-waveform
generating device, the first pulse tube and the second pulse tube,
and pre-cooling the refrigerant gas to be flowed into the first
pulse tube and the second pulse tube;
[0056] a pressure-waveform phase controlling element having a first
inertance tube communicating with the high-temperature end of the
first pulse tube and having a flow passage with a smaller inside
diameter than an inside diameter of the first pulse tube, a first
buffer tank communicating with the high-temperature end of the
first pulse tube by way of the first inertance tube, a second
inertance tube communicating with the high-temperature end of the
second pulse tube and having a flow passage with a smaller inside
diameter than an inside diameter of the second pulse tube, and a
second buffer tank communicating with the high-temperature end of
the second pulse tube by way of the second inertance tube, and
controlling pressure-waveform phases of the refrigerant gas for
generating refrigeration; and
[0057] a vacuum heat-insulation bath having a vacuum
heat-insulation chamber for accommodating the second pulse tube at
least,
[0058] wherein at least a part of the second inertance tube is
brought into contact with the low-temperature end of the first
pulse tube thermally.
[0059] In accordance with the fifth aspect of the pulse tube
refrigerator of the present invention, the second inertance tube is
brought into contact with the low-temperature end of the first
pulse tube thermally. In this instance, at least a part of the
second inertance tube is cooled by refrigeration from the
low-temperature end of the first pulse tube. Accordingly, it is
possible to maintain the refrigerant gas, which flows in the second
inertance tube, at a low temperature. Consequently, it is possible
to enhance the compression ratio of the refrigerant gas within a
cooling circuit, the refrigeration amount generated at the
lower-temperature end of the second pulse tube becomes large, and
it becomes advantageous for enhancing the cooling capacity of the
pulse tube refrigerator.
[0060] Especially, since the inside diameter of the second
inertance tube's flow passage is small so that, compared with the
case where the inside diameter of the second inertance tube's flow
passage is large, it is possible to efficiently cool the
refrigerant gas, which flows on the central side of the second
inertance tube, as well, in addition to the refrigerant gas, which
flows on the outer-wall side of the second inertance tube, it is
possible to efficiently cool the entirety of the refrigerant gas,
which flows within the second inertance tube.
[0061] In accordance with the fifth aspect of the pulse tube
refrigerator of the present invention, it is possible to exemplify
a mode in which the second inertance tube is brought into contact
with the low-temperature end of the first pulse tube thermally by
winding it around the lower-temperature end of the first pulse tube
in a spiral shape.
EFFECT OF THE INVENTION
[0062] In accordance with the present invention, it is possible to
provide a pulse tube refrigerator which is advantageous for
enhancing the refrigeration capacity generated at the
low-temperature end of a pulse tube.
BRIEF DESCRIPTION OF THE DRAWINGS
[0063] FIG. 1 relates to a First Embodiment Mode, and is a
constructional diagram for illustrating the concept of a pulse tube
refrigerator.
[0064] FIG. 2 relates to the First Embodiment Mode, and is a
constructional diagram for illustrating a contact portion between a
second inertance tube and a shield plate.
[0065] FIG. 3 relates to a Second Embodiment Mode, and is a
constructional diagram for illustrating the concept of a pulse tube
refrigerator.
[0066] FIG. 4 relates to a Third Embodiment Mode, and is a
constructional diagram for illustrating a contact state between a
second inertance tube and a shield plate.
[0067] FIG. 5 relates to a Fourth Embodiment Mode, and is a
constructional diagram for illustrating the vicinity of a second
buffer tank.
[0068] FIG. 6 relates to a Fifth Embodiment Mode, and is a
constructional diagram for illustrating the vicinity of a second
buffer tank.
[0069] FIG. 7 relates to a Sixth Embodiment Mode, and is a
constructional diagram for illustrating a state in which a second
inertance tube is wound around the low-temperature end of a first
buffer tank.
[0070] FIG. 8 relates to a prior art, and is a constructional
diagram for illustrating the concept of a pulse tube
refrigerator.
[0071] FIG. 9 relates to a prior art, and is a constructional
diagram for illustrating the concept of a pulse tube
refrigerator.
BEST MODE FOR CARRYING OUT THE INVENTION
[0072] Hereinafter, regarding the embodiment modes of the present
invention, they will be described using the drawings.
First Embodiment Mode
[0073] A First Embodiment Mode is illustrated in FIG. 1. In FIG. 1,
1 is a linearly-driving type compressor, and can function as a
pressure-waveform generating device for generating a pressure
waveform of gaseous refrigerant gas. In accordance with the
compressor 1, the space between a piston 2 and a piston 3, which
can move reciprocally, is adapted to a compression portion 4. The
compression portion 4 communicates with an end 6a of a radiator 6
by way of a pipe 5, and another end 6b of the radiator 6 is
connected with a first cold accumulator 8 in which a
cold-accumulating material 7, such a wire net, is filled. At a
low-temperature end 8b of the first cold accumulator 8, a
cylinder-shaped connecting member 9, with which a second cold
accumulator 10 is connected, is disposed. The inside of the second
cold accumulator 10 is filled with a sphere-shaped
cold-accumulating material 12, such as lead or rare-earth, which
has a cold-accumulating function. The second cold accumulator 10 is
maintained at a lower temperature than the first cold accumulator
8. Inside the connecting member 9, a flow-passage member 11 is
disposed. The flow-passage member 11 is communicated with a first
pulse tube 14 and a second pulse tube 20, and refrigerant gas,
which is headed to the first pulse tube 14, and refrigerant gas,
which is headed to the second pulse tube 20, flow.
[0074] As shown in FIG. 1, on an outer wall surface, a
circumferential surface of the aforementioned connecting member 9,
an end 13a of a pipe 13 for passing refrigerant is disposed.
Another end 13b of the pipe 13 communicates with a first heat
exchanger 15. The first heat exchanger 15 is disposed at a
low-temperature end 14L of the first pulse tube 14.
[0075] The first pulse tube 14 is a longitudinally-long metallic
pipe-shaped member which has a hollow chamber into which
refrigerant gas can flow, and refrigerant gas, which has a pressure
waveform generated by the compression portion 4, flows into it.
Here, an upper-end side of the first pulse tube 14 (another end) is
adapted to a high-temperature end 14H, and a lower-end side of the
first pulse tube 14 (an end) is adapted to a low-temperature end
14L. The low-temperature end 14L is placed on a lower side in order
to inhibit the thermal convection of refrigerant gas.
[0076] As shown in FIG. 1, an end of the first radiator 16 is
connected with the high-temperature end 14H of the first pulse tube
14, and the first radiator 16 is placed on an outer side than a
vacuum heat-insulation bath 24. Another end of the first radiator
16 is connected with an end 17a of a metallic first inertance tube
17 which is formed of a long pipe functioning as a first
communication tube. The first inertance tube 17 has a function
equivalent to reactance in electric circuit. The inside diameter of
the first inertance tube 17 is smaller than the inside diameter of
the first pulse tube 14 and the inside diameter of the first buffer
tank 18. Another end 17b of the first inertance tube 17 is
connected with the first buffer tank 18. The first buffer tank 18
has a tank chamber 18w whose volume is large.
[0077] Here, the refrigerant gas in the first pulse tube 14 goes to
and fro with respect to the inside of the first buffer tank 18 by
way of the first inertance tube 17, and thereby the phase and
pressure amplitude of the refrigerant gas is adjusted. Therefore,
the first inertance tube 17 and the first buffer tank 18 can
function as a pressure-waveform phase controlling element, which
controls the pressure-waveform phase and pressure amplitude of
refrigerant gas, for generating refrigeration at the
low-temperature end 14L of the first pulse tube 14. The first
inertance tube 17 and the first buffer tank 18 are placed on an
outside of the vacuum heat-insulation bath 24, as shown in FIG.
1.
[0078] As shown in FIG. 1, the low-temperature end 10L of the
second cold accumulator 10 communicates with a second heat
exchanger 30, which has a function of being capable of cooling
refrigeration gas by means of heat exchange, by way of a pipe 19.
The second heat exchanger 30 is disposed at the low-temperature end
20L of the second pulse tube 20 (a lower temperature than the
low-temperature end 14L of the first pulse tube 14). The second
pulse tube 20 is a long metallic pipe-shaped member which has a
longitudinally-long hollow chamber into which refrigerant gas can
flow. Here, the length of the second pulse tube 20 is set shorter
than the length of the first pulse tube 14. Moreover, the inside
diameter of the second pulse tube 20 is set smaller than the inside
diameter of the first pulse tube 14. Therefore, the volume of the
second pulse tube 20 is set smaller than the volume of the first
pulse tube 14. An upper-end side of the second pulse tube 20 is
adapted to a high-temperature end 20H, and a lower-end side of the
second pulse tube 20 is adapted to a low-temperature end 20L. The
low-temperature end 20L is disposed on a lower side in order to
inhibit the thermal convection of refrigerant gas.
[0079] At the high-temperature end 20H of the second pulse tube 20,
a second radiator 21 having a cooling function is disposed. The
second radiator 21 contacts thermally with the outer surface of the
contact member 9's cylinder portion 9a by way of a flange portion
9b having heat transferability. As described above, on the inner
surface of the contact member 9's cylinder portion 9a, a flow
passage is disposed, in flow passage which the refrigerant gas
cooled by refrigeration generated at the low-temperature end 14L of
the first pulse tube 14 flows. Therefore, the second radiator 21 is
cooled by the refrigerant gas flowing in the contact member 9's
cylinder portion 9a.
[0080] In other words, since the high-temperature end 20H of the
second pulse tube 20 contacts thermally with the second radiator 21
and is cooled by the second radiator 21, as a result, the
high-temperature end 20H of the second pulse tube 20 comes to be
cooled by refrigeration generated at the low-temperature end 14L of
the first pulse tube 14. Since the high-temperature end 20H of the
second pulse tube 20 is thus maintained at a low temperature by the
second radiator 21, even with an identical flow volume, it becomes
advantageous for making the volume of the refrigerant gas in the
second pulse tube 20 small, and it is possible to shorten the
length of the second pulse tube 20. Therefore, it becomes
advantageous for enhancing the compression ratio of a refrigeration
circuit, and accordingly it is possible to make the refrigeration
amount, which generates at the low-temperature end 20L of the
second pulse tube 20, larger than the prior arts.
[0081] In accordance with the present embodiment mode, a shield
plate 25, which can function as a cooling element, is disposed, as
shown in FIG. 1. The shield plate 25 is made of a metal of good
heat transferability, since a part 25m of the shield plate 25
contacts thermally with the low-temperature end 14L of the first
pulse tube 14, as shown in FIG. 1, the shield plate 25 is cooled to
a low temperature.
[0082] With the shield plate 25 as a cooling element, a box-shaped
shield case 26 contacts thermally. The shield case 26 is placed on
a lower side of the shield plate 25, and forms a shield chamber
26w. The shield chamber 26w communicates with the vacuum
heat-insulation chamber 24w, and is maintained in a high vacuum
state in the same manner as the vacuum heat-insulation chamber
24w.
[0083] As shown in FIG. 2, a metallic second inertance tube 22,
which is formed of a long pipe, contacts thermally with the shield
plate 25, and is held thereto. The second inertance tube 22
functions as a second communication pipe, which communicates the
second buffer tank 23 with the second pulse tube 20, and has a
function of throttling gas flow volume; and the inside diameter of
the second inertance tube 22 is smaller than the inside diameter of
the second pulse tube 20 and the inside diameter of the second
buffer tank 23.
[0084] Moreover, as shown in FIG. 1, a top portion 23u of the
second buffer tank 23 contacts thermally with the shield plate 25,
and is held thereto. The second buffer tank 23 is placed on the
lower-surface side of the shield plate 25. The second buffer tank
23 has a tank chamber 23w whose volume is large. The volume of the
tank chamber 23w is made smaller than the volume of the first
buffer tank 18's tank chamber 18w. As set forth above, the second
buffer tank 23 also contacts thermally with the shield plate 25 as
a cooling element. Thus, the second buffer tank 23 is cooled by the
shield plate 25, and the refrigerant gas within the second buffer
tank 23 is maintained at a low temperature.
[0085] Here, the refrigerant gas in the second pulse tube 20 goes
to and fro with respect to the inside of the second buffer tank 23
by way of the second inertance tube 22, and thereby the phase and
pressure amplitude of the refrigerant gas, which is supplied to the
second pulse tube 20, is adjusted. Therefore, the second inertance
tube 22 and the second buffer tank 23 can function as a
pressure-waveform phase controlling element, which controls the
pressure-waveform phase of refrigerant gas, for generating
refrigeration at the low-temperature end 20L of the second pulse
tube 20.
[0086] In accordance with the present embodiment mode, the second
buffer tank 23 is not placed in air, but is disposed within the
vacuum heat-insulation chamber 24w of the vacuum heat-insulation
bath 24, as shown in FIG. 1. Especially, the second buffer tank 23
is disposed within the shield chamber 26w of the shield case 26
within the vacuum heat-insulation bath 24. The shield case 26
functions as a heat-radiation transmission inhibitor element for
inhibiting the transmission of heat radiation from the outside.
[0087] Accordingly, it is possible to maintain the refrigerant gas
within the second buffer tank 23 at a much lower temperature. The
inside of the vacuum heat-insulation chamber 24w of the vacuum
heat-insulation bath 24 is connected with a vacuum pump 24x, and is
maintained in a high-vacuum state (10.sup.-4 Torr or less
.apprxeq.133.times.10.sup.-4 Pa or less). The vacuum
heat-insulation bath 24 is good in terms of the heat
insulatability.
[0088] Note that wall bodies of the vacuum heat-insulation bath 24
are formed of a highly heat-insulative material which inhibits heat
transmission. The shield case 26 is disposed within the vacuum
heat-insulation bath 24, suppresses heat radiation from the
outside, and is formed of a metal, which is of good heat
transferability, as the substrate.
[0089] In accordance with the present embodiment mode, the second
cold accumulator 10, the second pulse tube 20 and the second
radiator 21 are disposed within the shield chamber 26w of the
shield case 26, in addition to the second buffer tank 23, as shown
in FIG. 1, and their thermal contacts with the air are prohibited.
As shown in FIG. 1, the first pulse tube 14 is outside the shield
case 26, and is accommodated within the vacuum heat-insulation bath
24.
[0090] In service, the pistons 2, 3 reciprocate with a frequency
while facing to each other. Thus, the refrigerant gas within the
compression portion 4 of the compressor 1 is compressed with the
same frequency as that of the pistons 2, 3, and a pressure waveform
for the refrigerant gas (helium in general) is generated. And, the
gas-pressure resonance frequency within the first buffer tank 18
and first inertance tube 17, and the gas-pressure resonance
frequency within the second buffer tank 23 and second inertance
tube 22 are such that their dimensional specifications are set up
so as to become a frequency which is virtually equal to that of the
movements of the pistons 2, 3. Thus, at the low-temperature end 14L
of the first pulse tube 14 as well as at the low-temperature end
20L of the second pulse tube 20, pressure waveforms, which are
close to the Stirling cycle substantially, are obtained, and it is
set up so that it is possible to obtain a refrigeration amount
close to the ideal at the low-temperature end 20L of the second
pulse tube 20.
[0091] For example, depending on the operational circumstances,
40-100 K refrigeration can be obtained at the low-temperature end
14L of the first pulse tube 14, and 10-30 K refrigeration can be
obtained at the low-temperature end 20L of the second pulse tube
20. Depending on the operational circumstances, the vacuum
heat-insulation bath 24 and shield case 26 have a function of
inhibiting the heat transfer from the vacuum heat-insulation bath
24, and the temperature of the shield case 26's shield chamber 26W
is 40-100 K approximately in general. The shield case 26 has a
function of inhibiting the radiation heat from the vacuum
heat-insulation chamber 24.
[0092] In accordance with the present embodiment mode, the
refrigerant gas, which has become a low temperature by
refrigeration generated at the low-temperature end 14L of the first
pulse tube 14, flows on the inner surface of the contact member 9's
cylinder portion 9a. As a result, since the contact member 9 is
cooled, the second radiator 21, which contacts thermally with the
contact member 9, becomes a low temperature. Eventually, the
high-temperature end 20H of the second pulse tube 20, which
contacts thermally with the second radiator 21, is maintained at a
low temperature so that it is maintained at a temperature which is
virtually close to the temperature of the first pulse tube 14's
low-temperature end 14L.
[0093] Thus, in accordance with the present embodiment mode, since
the high-temperature end 20H of the second pulse tube 20 can be
maintained at a lower temperature by the second radiator 21, it
becomes advantageous for reducing the gaseous volume of the
refrigerant gas within the second pulse tube 20, and the length of
the second pulse tube 20 can be made shorter than the lengths of
the second pulse tubes according to prior arts so that it is
possible to downsize the second pulse tube 20.
[0094] As described above, in accordance with the present
embodiment mode, since the second buffer tank 23 is disposed within
the vacuum heat-insulation chamber 24w of the vacuum
heat-insulation bath 24, it is possible to suppress the thermal
contact between the second buffer tank 23 and the air, and it is
possible to always keep the second buffer tank 23 at a low
temperature, and it is advantageous for enhancing the refrigeration
capacity in the pulse tube refrigerator.
[0095] Especially, since the second buffer tank 23 is disposed
within the shield chamber 26w of the highly heat-insulatable shield
case 26 which is placed within the vacuum heat-insulation bath 24,
it is possible to keep the second buffer tank 23 at a much lower
temperature, and eventually it is possible to keep the refrigerant
gas within the second buffer tank 23 as well at a low
temperature.
[0096] Consequently, in accordance with the present embodiment
mode, it becomes advantageous for further enhancing the compression
ratio of the refrigerant gas within a cooling circuit, the
refrigeration amount generated at the lower-temperature end 20L of
the second pulse tube 20 enlarges, and it becomes advantageous for
enhancing the refrigeration capacity of the pulse tube
refrigerator.
[0097] Further, in accordance with the present embodiment mode, the
second inertance tube 22, which carries out flowing in and flowing
out the refrigerant gas with respect to the second buffer tank 23,
is disposed within the vacuum heat-insulation chamber 24w of the
vacuum heat-insulation bath 24, along with the second buffer tank
23. Accordingly, not only the thermal contact between the second
buffer tank 23 and the air is suppressed, but also the thermal
contact between the second inertance tube 22 and the air can be
suppressed, and it is possible to always keep the second inertance
tube 22 at a low temperature. Consequently, in accordance with the
present embodiment mode, it becomes advantageous for further
enhancing the compression ratio of the refrigerant gas within a
cooling circuit, and the refrigeration amount generated at the
lower-temperature end 20L of the second pulse tube 20 enlarges.
[0098] Especially, as shown in FIG. 1, since the second inertance
tube 22 is disposed within the shield chamber 26w of the shield
case 26 within the vacuum heat-insulation bath 24, it is possible
to keep the second inertance tube 22 at a much lower temperature,
and it is possible to keep the refrigerant gas in the second
inertance tube 22 at a low temperature. Consequently, in accordance
with the present embodiment mode, it becomes advantageous for
further enhancing the compression ratio of the refrigerant gas
within a cooling circuit, and the refrigeration amount generated at
the lower-temperature end 20L of the second pulse tube 20
enlarges.
[0099] Furthermore, the shield plate 25 as the cooling element is
cooled by the low-temperature end 14L of the first pulse tube 14,
and the second inertance tube 22 contacts thermally with the shield
plate 25. Accordingly, the second inertance tube 22 is cooled by
refrigeration generated at the low-temperature end 14L of the first
pulse tube 14 by way of the shield plate 25. Especially, since the
inside diameter of the second inertance tube 22's flow passage is
small, it is possible to cool not only the refrigerant gas flowing
on the outer peripheral side of the second inertance tube 22 but
also the refrigerant gas flowing on the center-axis core side of
the second inertance tube 22. Therefore, it is possible to
efficiently cool the entirety of the refrigerant gas flowing in the
second inertance tube 22.
[0100] That is, in accordance with the present embodiment mode,
since it is possible to efficiently cool the refrigerant gas in the
second inertance tube 22 with the shield plate 25 as the cooling
element, it is possible to keep the refrigerant gas flowing in the
second inertance tube 22 at a much lower temperature. Hence, it
becomes advantageous for further enhancing the compression ratio of
the refrigerant gas within a cooling circuit, the high-temperature
end 20H of the second pulse tube 20 becomes a much lower
temperature, and the refrigeration amount generated at the
lower-temperature end 20L of the second pulse tube 20 improves
furthermore.
[0101] Further, since it is possible to make the refrigerant gas
flowing in the second inertance tube 22 a further low temperature,
the flow-passage resistance of the second inertance tube 22 reduces
so that it is possible to make the viscous loss of the gas flowing
in the second inertance tube 22 less. As a result, since it is
possible to make the phase of the refrigerant gas flowing into the
high-temperature end 20H of the second pulse tube 20 and the
gaseous amount favorable, the refrigeration capacity enlarges.
[0102] When the refrigerant gas within the second inertance tube 22
can be cooled to a low-temperature side as described above, it is
possible to clarify the peak of the resonance frequency of the
gaseous pressures within the second buffer tank 23 and second
inertance tube 22, and it becomes advantageous for further
improving the refrigeration amount generated at the low-temperature
end 20H of the second pulse tube 20.
[0103] Additionally, in accordance with the present embodiment
mode, the second buffer tank 23 contacts thermally with the shield
plate 25 as the cooling element, shield plate 25 which joins
thermally with the low-temperature end 14L of the first pulse tube
14. Therefore, the second buffer tank 23 is cooled by refrigeration
generated at the low-temperature end 14L of the first pulse tube 14
by way of the shield plate 25. Accordingly, it is possible to keep
the refrigerant gas in the second buffer tank 23 at a much lower
temperature. Hence, it becomes advantageous for further enhancing
the compression ratio of the refrigerant gas within a cooling
circuit, the high-temperature end 20H of the second pulse tube 20
becomes a much lower temperature, and eventually the refrigeration
amount generated at the low-temperature end 20L of the second pulse
tube 20 improves furthermore.
[0104] As described above, in accordance with the present
embodiment mode, since it is advantageous for enhancing the
compression ratio of the refrigerant gas within a cooling circuit,
it is possible to make the volume of the second pulse tube 20 less
than the volumes of the second pulse tubes according to prior arts.
Thus, it is possible to shorten the length of the second pulse tube
20. Accordingly, it is advantageous in view of inhibiting the
vibrations of the second pulse tube 20, and is appropriate for
using the pulse tube refrigerator in vibrating environments.
[0105] Note that, in accordance the aforementioned embodiment mode,
the second radiator 21, which is disposed at the high-temperature
end 20H of the second pulse tube 20, is brought into contact with
the contact member 9 thermally, however, not limited to this, the
second radiator 21 can be directly brought into contact with the
low-temperature end 14L of first pulse tube 14.
[0106] Moreover, the aforementioned embodiment mode is an example
which is applied to a 2-stage pulse tube refrigerator, however, not
limited to this, it can be applied to pulse tube refrigerators of 3
stages or more.
Second Embodiment Mode
[0107] FIG. 3 illustrates a Second Embodiment Mode. The Second
Embodiment Mode is a modified mode of the First Embodiment Mode.
The Second Embodiment Mode is the same constitution as the First
Embodiment Mode basically, and performs the same operations and
effects basically. Common parts are designated at common symbols.
Hereinafter, portions, which differ from the First Embodiment Mode,
will be described mainly. Specifically, a sub cold accumulator 40
is disposed between the first heat exchanger 15 and pipe 13 of the
First Embodiment Mode. And, the shield plate 25 as the cooling
element is brought into contact with and disposed at the
high-temperature end of the sub cold accumulator 40. In accordance
with the Second Embodiment Mode, the temperature of refrigeration
generated at the low-temperature end 14L of the first pulse tube 14
is low sufficiently, and it is a modal example in the case that the
temperature at the high-temperature end 20H of the second pulse
tube 20 can be higher than the temperature at the low-temperature
end 14L of the first pulse tube 14.
Third Embodiment Mode
[0108] FIG. 4 illustrates a Third Embodiment Mode. The Third
Embodiment Mode is a modified mode of the First Embodiment Mode.
The Third Embodiment Mode is the same constitution as the First
Embodiment Mode basically, and performs the same operations and
effects basically. Common parts are designated at common symbols.
Hereinafter, portions, which differ from the First Embodiment Mode,
will be described mainly. Specifically, as shown in FIG. 4, the
second buffer tank 23 contacts thermally with the shield plate 25
as the cooling element, and is cooled by refrigeration generated at
the low-temperature end 14L of the first pulse tube 14 by way of
the shield plate 25. Accordingly, it is possible to keep the
refrigerant gas in the second buffer tank 23 at a much lower
temperature. As shown in FIG. 4, the shield plate 25 has a flanged
portion 25r, which is bent toward the second buffer tank 23 and
contacts thermally with an outer wall surface of the second buffer
tank 23, for facilitating the transfer of heat. The heat-transfer
facilitating flanged portion 25r increases the contact portion
(heat-transfer area) with the second buffer tank 23 to enhance the
cooling ability of the refrigerant within the second buffer tank
23.
Fourth Embodiment Mode
[0109] FIG. 5 illustrates a Fourth Embodiment Mode. The Fourth
Embodiment Mode is a modified mode of the First Embodiment Mode.
The Fourth Embodiment Mode is the same constitution as the First
Embodiment Mode basically, and performs the same operations and
effects basically. Common parts are designated at common symbols.
Hereinafter, portions, which differ from the First Embodiment Mode,
will be described mainly. Specifically, the most part of the second
buffer tank 23 is placed within the vacuum heat-insulation chamber
24w of the vacuum heat-insulation bath 24, however, only a part
(upper-end portion) of the second buffer tank 23 is exposed beyond
the vacuum heat-insulation bath 24, as shown in FIG. 5. However,
among the second buffer tank 23, in the part being exposed beyond
the second buffer tank 23, a heat-insulation material 23m of good
heat insulatability is placed. The heat-insulation material 23m can
inhibit the temperature increment of the refrigerant gas within the
second buffer tank 23.
Fifth Embodiment Mode
[0110] FIG. 6 illustrates a Fifth Embodiment Mode. The Fifth
Embodiment Mode is a modified mode of the First Embodiment Mode.
The Fifth Embodiment Mode is the same constitution as the First
Embodiment Mode basically, and performs the same operations and
effects basically. Hereinafter, portions, which differ from the
First Embodiment Mode, will be described mainly. Common parts are
designated at common symbols. Specifically, the second buffer tank
23 is placed within the vacuum heat-insulation chamber 24w of the
vacuum heat-insulation bath 24, however, only a tube-shaped portion
23x, which protrudes from the second buffer tank 23, is exposed
beyond the vacuum heat-insulation bath 24. To the tube-shaped
portion 23x, a measuring gauge 23k, such as sensors for detecting
physical quantities like the pressure and temperature of the
refrigerant gas within the second buffer tank 23, is installed,
depending on needs. Since the measuring gauge 23k is exposed beyond
the vacuum heat-insulation bath 24, it is advantageous for the
maintenance and inspection of the measuring gauge 23k.
Sixth Embodiment Mode
[0111] FIG. 7 illustrates a Sixth Embodiment Mode. The Sixth
Embodiment Mode is a modified mode of the First Embodiment Mode.
The Sixth Embodiment Mode is the same constitution as the First
Embodiment Mode basically, and performs the same operations and
effects basically. Hereinafter, portions, which differ from the
First Embodiment Mode, will be described mainly. Specifically,
since the length of the second inertance tube 22 is long, the
entirety or a part of the second inertance tube 22 is wound around
the low-temperature end 14L of the first pulse tube 14 in the
peripheral direction in order to use the second inertance tube 22
effectively. The second inertance tube 22 is cooled by
refrigeration generated at the low-temperature end 14L (cooling
element) of the first pulse tube 14. The second inertance tube 22
is placed within the vacuum heat-insulation chamber 24w.
[0112] (Others) The following technical ideas can be grasped from
the aforementioned descriptions.
[0113] Additional Note No. 1: a pulse tube refrigerator being
characterized in that, in claim 1, the buffer tank communicates
with the high-temperature end of the pulse tube by way of an
inertance tube having a flow passage whose inside diameter is
smaller than an inside diameter of the pulse tube.
[0114] Additional Note No. 2: a pulse tube refrigerator being
characterized in that, in additional note No. 1, the inertance tube
is placed within the vacuum heat-insulation chamber of the vacuum
heat-insulation bath.
[0115] Additional Note No. 3: a pulse tube refrigerator being
characterized in that, in additional note No. 1 or 2, the pulse
tube is constituted of a first pulse tube, into which refrigerant
gas with a pressure waveform flows, one of whose ends is adapted to
a low-temperature end, the other one of whose ends is adapted to a
high-temperature end, and a second pulse tube, one of whose ends is
adapted to a low-temperature end, the low-temperature end becoming
a lower temperature than the low-temperature end of the first pulse
tube, the other one of whose ends is adapted to a high-temperature
end.
[0116] Additional Note No. 4: a pulse tube refrigerator being
characterized in that, in additional note No. 3, the cold
accumulator is disposed between the pressure-waveform generating
device, the first pulse tube and the second pulse tube, and
pre-cools the refrigerant gas to be flowed into the first pulse
tube and/or the second pulse tube.
[0117] Additional Note No. 5: a pulse tube refrigerator being
characterized in that, in additional note No. 3, the
pressure-waveform phase controlling element has a first inertance
tube communicating with the high-temperature end of the first pulse
tube and having a flow passage with a smaller inside diameter than
an inside diameter of the first pulse tube, a first buffer tank
communicating with the high-temperature end of the first pulse tube
by way of the first inertance tube, a second inertance tube
communicating with the high-temperature end of the second pulse
tube and having a flow passage with a smaller inside diameter than
an inside diameter of the second pulse tube, and a second buffer
tank communicating with the high-temperature end of the second
pulse tube by way of the second inertance tube.
[0118] Additional Note No. 6: a pulse tube refrigerator being
characterized in that, in additional note No. 5, a cooling element
contacting thermally with the low-temperature end of the first
pulse tube and being cooled by refrigeration from the
low-temperature end of the first pulse tube is disposed, and the
cooling element is brought into contact with the second inertance
tube thermally.
[0119] Additional Note No. 7: a pulse tube refrigerator being
characterized in that, in additional note No. 5 or 6, a cooling
element contacting thermally with the low-temperature end of the
first pulse tube and being cooled by refrigeration from the
low-temperature end of the first pulse tube is disposed, and the
cooling element is brought into contact with the second buffer tank
thermally.
[0120] Additional Note No. 8: a pulse tube refrigerator being
characterized in that, in additional note Nos. 5 through 7, at
least a part of the second inertance tube is brought into contact
with the low-temperature end of the first pulse tube thermally.
INDUSTRIAL APPLICABILITY
[0121] The present invention can be utilized for pulse tube
refrigerators.
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