U.S. patent application number 13/195891 was filed with the patent office on 2012-02-09 for cryogenic refrigerator coupling structure.
This patent application is currently assigned to Hitachi, Ltd.. Invention is credited to Hiroyuki TANAKA.
Application Number | 20120031110 13/195891 |
Document ID | / |
Family ID | 44674188 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120031110 |
Kind Code |
A1 |
TANAKA; Hiroyuki |
February 9, 2012 |
CRYOGENIC REFRIGERATOR COUPLING STRUCTURE
Abstract
For providing a refrigerator coupling structure for enabling
attaching/detaching and re-cooling of the refrigerator in a short
time-period, by suppressing a heat movement from the refrigerator
at the room temperature to an object to be cooled, which is cooled
down to cryogenic temperature when attaching a cryogenic
refrigerator thereon, while suppressing a volume of heat invasion
into the object to be cooled, it has a heat contact portion having
a flexible portion at least in a part thereof, which is coupled
with a cold stage of the cryogenic refrigerator 1, wherein on an
outer peripheral portion of this heat contact portion is provided a
heat contracting ring, which has a heat contraction rate larger
than that of the heat contact portion.
Inventors: |
TANAKA; Hiroyuki; (Mito,
JP) |
Assignee: |
Hitachi, Ltd.
|
Family ID: |
44674188 |
Appl. No.: |
13/195891 |
Filed: |
August 2, 2011 |
Current U.S.
Class: |
62/51.1 |
Current CPC
Class: |
F25B 9/10 20130101; F25D
19/006 20130101 |
Class at
Publication: |
62/51.1 |
International
Class: |
F25B 19/00 20060101
F25B019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2010 |
JP |
2010-174082 |
Claims
1. A coupling structure for a cryogenic refrigerator in a cryogenic
storage container, comprising: a vacuum container, which stores a
cooling object in an inside thereof; a heat shield, which is
provided between said cooling object and said vacuum container; a
cold stage, which is configured to cool said cooling object and
said heat shield down to cryogenic temperature; and a cryogenic
refrigerator, which is coupled with said vacuum container through a
coupling structure, further having in said coupling structure: a
heat contact portion, which is coupled with said cold stage; and a
heat contracting ring, which is provided on an outer peripheral
portion of said heat contact portion and also has a thermal
contraction rate larger than that of said heat contact portion.
2. The coupling structure in the cryogenic storage container, as
described in the claim 1, wherein said cold stage has a first cold
stage and a second cold stage, and further having: a coupling
portion between said heat shield and the first cold stage of said
cryogenic refrigerator, and a coupling portion between said cooling
object and the second cold stage of said cryogenic refrigerator,
and further having, in said two (2) coupling portions; and heat
contact portions coupled with the first cold stage of said
cryogenic refrigerator and the second cold stage of said cryogenic
refrigerator, respectively, wherein the heat contracting ring
having the thermal contraction rate larger than that of said heat
contact portion is provided on the outer peripheral portion of said
heat contact portion.
3. The coupling structure in the cryogenic storage container, as
described in the claim 1, wherein said heat contact portion has a
flexible portion at least a part thereof.
4. The coupling structure in the cryogenic storage container, as
described in the claim 1, wherein said heat contact portion is
divided in peripheral diction thereof.
5. The coupling structure in the cryogenic storage container, as
described in the claim 1, wherein a clearance is produced between
the first cold stage of said cryogenic refrigerator and said heat
shield when the cryogenic refrigerator is at room temperature, and
the heat contracting ring contracts, thermally, in a process where
the first cold stage of the cryogenic refrigerator reaches to a
condition of the cryogenic temperature, whereby the heat contact
portion and the heat shield are in thermal contact with each other,
automatically.
6. The coupling structure in the cryogenic storage container, as
described in the claim 1, wherein a clearance is produced between
the second cold stage of said cryogenic refrigerator and said
cooling object when the cryogenic refrigerator is at room
temperature, and the heat contracting ring contracts, thermally, in
a process where the second cold stage of the cryogenic refrigerator
reaches to a condition of the cryogenic temperature, whereby the
heat contact portion and the cooling object are in thermal contact
with each other, automatically.
7. A cryogenic storage container having the coupling structure of
the cryogenic storage container, as described in the claim 1.
8. A cryogenic storage container having the coupling structure of
the cryogenic storage container, as described in the claim 2.
9. A cryogenic storage container having the coupling structure of
the cryogenic storage container, as described in the claim 3.
10. A cryogenic storage container having the coupling structure of
the cryogenic storage container, as described in the claim 4.
11. A cryogenic storage container having the coupling structure of
the cryogenic storage container, as described in the claim 5.
12. A cryogenic storage container having the coupling structure of
the cryogenic storage container, as described in the claim 6.
Description
[0001] This application relates to and claims priority from
Japanese Patent Application No. 2010-174082 filed on Aug. 3, 2010,
the entire disclosure of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an apparatus for using a
cryogenic refrigerator, and it relates to a refrigerator coupling
structure for enabling attaching/detaching of a refrigerator under
a condition of cooling an object to be cooled down to the cryogenic
temperature, in particular, in a cryo-cooled superconducting
magnet.
[0003] The cryo-cooled superconducting magnet for cooling the
superconducting magnet by the cryogenic refrigerator has a
remarkable characteristic that there is no necessity of liquid
helium. Because of no necessity of the liquid helium, there is no
need of energy consumption in a process for producing the liquid
helium, and this enables an advancement of energy saving. Such
cryo-cooled superconducting magnet, because it can achieve a
cryogenic environment, easily, by only pushing down one (1) piece
of button, but without supplying the liquid helium thereto, is
expected to be applied into various technical fields, for example,
a magnetic levitation train, measurement of physical properties
under circumstances of strong magnetic field, magnetization and
magnetic separation, etc.
[0004] The cryogenic refrigerator for achieving the cryogenic
environment without using the liquid helium therein must be
conducted with maintenances thereon, periodically, because of the
structural problems, which will be mentioned hereinafter. Thus, it
is said that, on a Gifford-McMahon (GM) type refrigerator, which is
applied, in general, in the cryo-cooled superconducting magnet, the
maintenances must be conducted, for example, one (1) time per a
year or every 15,000 hours. This is caused due to friction
accompanying the reciprocal movement of a displacer, which executes
compression/expansion and heat-exchange within the cryogenic
refrigerator, and the parts rubbed must be exchanged. Because of
gradual deterioration of purity of helium gas, which is filled up
within the cryogenic refrigerator, it is also necessary to replace
the helium gas.
[0005] For executing maintenance of the cryogenic refrigerator, it
is necessary to increase temperature of that cryogenic refrigerator
up to the room temperature, once. The time-duration for increasing
temperature can be shortened through heating by a heater; however,
there is a problem that it also increases temperature the object to
be cooled, which is unified with the cryogenic refrigerator in one
body. Also, heat capacity of the object to be cooled, which is
coupled with a cold stage of the cryogenic refrigerator, is larger
than the heat capacity of the cryogenic refrigerator itself, and
there is a problem that the time-duration for increasing the
temperature when the cryogenic refrigerator and the object to be
cooled are unified in one body. Further, since cooling must rely on
only the cooling capacity of the cryogenic refrigerator, there is
also other problem that, for the system having the longer
time-duration for increasing temperature, the cooling time thereof
is longer.
[0006] Within the cryo-cooled superconducting magnet for cooling
the object to be cooled by only the cryogenic refrigerator, because
of a possibility that temperature of the object to be cooled
increases when executing maintenance on the cryogenic refrigerator,
and that it is not in the condition of superconducting, there is
necessity of demagnetizing the magnetic field, which is generated
by the superconducting magnet. Accordingly, during the maintenance,
it cannot show or exhibit the function as the magnet . For
achieving re-magnetization thereof as early as possible, it is
necessary to bring the increase of temperature of the
superconducting magnet to be small, and also to cool it, again,
down to the excitable temperature thereof in a short
time-period.
[0007] The cooling structure of the refrigerator, according to the
conventional cryogenic refrigerator, is shown in FIG. 7. The
cryogenic refrigerator 1 is attached on a vacuum container 3,
wherein the object 20 to be cooled and a heat shield 4 are cooled
by a first cold stage 2 and a first cold stage 7. Peripheries of
the object 20 to be cooled and the heat shield 4 are in the vacuum
condition, so as to suppress an amount of movement of heats from
the vacuum container 3 of the room temperature.
[0008] When conducting the maintenance on the cryogenic
refrigerator 1, it must be separated from, upon contacting surfaces
between the second cold stage 2 of the cryogenic refrigerator 1 and
the object to be cooled, and between the first cold stage 7 and the
heat shield 4. For brining the peripheries of the cryogenic
refrigerator 1 into the atmospheric pressure in that instance, a
vacuum wall 31 is provided surrounding the cryogenic refrigerator
1. Parts of the object 20 to be cooled and the heat shield 4 are
also utilized as a part of the vacuum container 3.
[0009] The maintenance methods for dissolving such problems can be
divided into two (2), roughly.
[0010] A first method is that of separating the cryogenic
refrigerator from the object to be cooled, physically. In the
Patent Publication 1, the cryogenic refrigerator is in contact with
the object to be cooled, thermally, in the form of suppressing it
on that object, wherein the cryogenic refrigerator and the object
to be cooled can be separated from each other, through loosing or
releasing screws of a portion of room temperature. Also, in the
Patent Publication 2, by loosing or releasing the screws, coupling
the cryogenic refrigerator and the object to be cooled, from the
portion of room temperature, the cryogenic refrigerator can be
separated from the object to be cooled. Further, in the Patent
Publication 3, a spring configuration is applied to coupling
portions between the cryogenic refrigerator and the object to be
cooled. In any one of those methods, it is characterized that the
cryogenic refrigerator and the object to be cooled are separated
while maintaining the object to be cooled in the cryogenic
temperature condition, as it is.
[0011] As a second method can be considered a method of increasing
temperature of only the cryogenic refrigerator under the condition
the cryogenic refrigerator and the object to be cooled are coupled
with each other. Thus, the cryogenic refrigerator and the object to
be cooled are separated, thermally, with applying a so-called a
thermal switch therein, and the temperature of only the cryogenic
refrigerator is increased. Since the displacer and so on are
exchanged within the cryogenic refrigerator after an increase of
the temperature, there is no necessity of replacing the main body
of the refrigerator.
[0012] In the Patent Document 2, as a heat transfer medium, helium
gas is filled up between the cryogenic refrigerator and the object
to be cooled, and it is used as the thermal switch. By discharging
the helium gas, the thermal coupling (or, heat connection) is
extinguished between the cryogenic refrigerator and the object to
be cooled, and then only the temperature of the cryogenic
refrigerator can be increased.
PRIOR ART DOCUMENTS
Patent Documents
[0013] [Patent Document 1] Japanese Patent Laying-Open No. Hei
9-287838 (1997); [0014] [Patent Document 2] Japanese Patent
Laying-Open No. 2004-294041 (2004); [0015] [Patent Document 3]
Japanese Patent Laying-Open No. Hei 1-196479 (1989); and [0016]
[Patent Document 4] Japanese Patent Laying-Open No. 2002-252111
(2002).
BRIEF SUMMARY OF THE INVENTION
[0017] Although various patents are already proposed, in relation
to the maintenances of the refrigerator, however each one of them
has a problem(s) to be dissolved, respectively.
[0018] In the Patent Document 1 mentioned above is disclosed that
the rotation speed of the cooling fan is controlled by the
inverter, however no disclosure is made in relation to the control
when an inverter trip is generated.
[0019] With the technology descried in the Patent Document 1, since
the object to be cooled is in contact with, applying pressure on
the surface thereof, it must has the structure for enduring such
surface pressure thereon, i.e., increasing the cross-section area
of a supporting portion, there is a problem that an amount of heats
invading into the object to be cooled comes to be large. With the
technology descried in the Patent Document 2, it is necessary to
bring the cold stage of the cryogenic refrigerator and the object
to be cooled to be in contact with each other, thermally, before
cooling the cryogenic refrigerator, and there is a problem that the
temperature of the object to be cooled increases due to the heat
capacity of the refrigerator. With the technology described in the
Patent Document 3, the refrigerator of the room temperature and the
object to be cooled, which is cooled down to the cryogenic
temperature, are in the form of being thermally in contact with
each other, there is a problem that the temperature of the object
to be cooled increases due to the heat capacity of the
refrigerator. With the technology described in the Patent Document
4, because of necessity of the time-period for increasing the
temperature of the cryogenic refrigerator up to the room
temperature, there is a problem that a long time-period is
necessary for executing the maintenance on the refrigerator.
[0020] An object, according to the present invention, is to provide
a refrigerator coupling structure for enabling detaching and
re-cooling of a refrigerator in a short time-period, by suppressing
an increase of temperature of a superconducting magnet, and also by
suppressing the movement of heats from the refrigerator of the room
temperature to the object to be cooled, which is cooled down to the
cryogenic temperature, when attaching the cryogenic refrigerator,
for shortening the time-period necessary for the maintenance and
the re-cooling, in the cryo-cooled superconducting magnet.
[0021] For accomplishing the object mentioned above is applied such
structures as is described in the claims, which will be mentioned
later, for example. According to the present invention, there are
included plural numbers of means for dissolving the problems
mentioned above, and if listing up an example thereof, for
dissolving the problem (s) mentioned above, a first feature of the
coupling structure for a cryogenic refrigerator, according to the
present invention, lies in that it has a heat contact portion being
coupled with a cold stage of the cryogenic refrigerator, and that a
heat contracting ring having a heat contraction rate larger than
that of the heat contact portion is provided on an outer peripheral
portion of this heat contact portion. With this, the contracting
ring having a large volume of heat contraction fastens an inside of
the heat contact portion, and thereby obtaining preferable heat
contact with the coupling portion between the heat contact portion
and a cooling object.
[0022] Also, a second feature of the present invention lies in
that, the heat contact portion is in contact with a flexible
portion. With provision of the flexible portion, it is easy for the
heat contact portion to change a position or an angle thereof, and
thereby obtaining preferable heat contact between the heat contact
portion and the coupling portion of the cooling object.
[0023] Also, a third feature of the present invention lies in that,
the heat contact portion is divided in a peripheral direction
thereof. The heat contact portion is divided, and the heat
contracting ring provided on an outer periphery of the heat contact
portion is cooled down, thereby to contract; thereby fastening the
heat contact portion. With this, it is possible to obtain the
preferable heat contact between the heat contact portion and the
coupling portion of the cooling object.
[0024] Also, a fourth feature of the present invention lies in
that, the heat contact portion, being in contact with the cold
stage of the cryogenic refrigerator, thermally, produces a
clearance between the heat contact portion and the cooling target,
when the cold stage of the cryogenic refrigerator is at the room
temperature. No heat contact is established between the cryogenic
refrigerator at the room temperature and the cooling object under
the condition of cryogenic temperature, and this prevents a heat
capacity of the cryogenic refrigerator at the room temperature from
moving into the cooling object under the condition of cryogenic
temperature.
[0025] Also, a fifth feature of the present invention lies in that,
the heat contact portion and the heat contracting ring, being
thermally coupled with the cold stage of the cryogenic
refrigerator, are cooled down, by starting the cryogenic
refrigerator after maintenance; thereby, the heat contracting ring
5 shrinks due to the thermal contraction, and then the coupling
portion and the coupling portion of the cooling object are
automatically in contact with each other, thermally. With this,
under the condition that the temperature of the cold stage of the
cryogenic refrigerator is high, the heat contact portion, being
thermally coupled with the cold stage of the cryogenic
refrigerator, and the coupling portion of the cooling object are in
the non-contact condition; thereby, it is possible to suppress a
heat invasion from the cold stage having high temperature into the
coupling portion of the cooling object, and also to suppress an
increase of temperature of the cooling object down to the lowest
limit. Accompanying with lowering of temperature of the cold stage
of the cryogenic refrigerator, the heat contracting ring, being
coupled with the heat contact portion, thermally contracts,
gradually, and therefore the heat contact portion and the coupling
portion of the cooling object are automatically in contact with
each other, thermally.
[0026] With provision of the coupling structure of the cryogenic
refrigerator according to the present invention, the movement of
heats from the cryogenic refrigerator, being in the condition of
the room temperature when maintenance is carried out thereon, to
the cooling object, and the temperature of the cooling object is
kept at the cryogenic temperature.
[0027] In the process of cooling the cryogenic refrigerator, the
heat transfer means, being in contact with the cryogenic
refrigerator, thermally, due to heat contraction of the heat
contracting ring, and the cooling object automatically come into
contact with each other, thermally. With such thermal contact
between the heat transfer means and the cooling object under the
condition where the heat transfer means is cooled by the cryogenic
refrigerator, it is possible to suppress an increase of temperature
of the cooling object down to the lowest limit.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0028] Those and other objects, features and advantages of the
present invention will become more readily apparent from the
following detailed description when taken in conjunction with the
accompanying drawings wherein:
[0029] FIG. 1 is a cross-section view of a coupling portion of a
cryogenic refrigerator, for showing a first embodiment of the
present invention;
[0030] FIG. 2 is a detailed cross-section view of the coupling
structure of the cryogenic refrigerator on a second cold stage,
according to the first embodiment;
[0031] FIGS. 3A and 3B are cross-section views when seeing the
coupling structure of the cryogenic refrigerator, according to the
first embodiment;
[0032] FIG. 4 is a detailed cross-section view of the coupling
structure of the cryogenic refrigerator on the second cold stage,
according to a second embodiment of the present invention;
[0033] FIG. 5 is a detailed cross-section view of the coupling
structure of the cryogenic refrigerator on a first cold stage,
according to a third embodiment of the present invention;
[0034] FIG. 6 is a detailed cross-section view of the coupling
structure of the cryogenic refrigerator on the first cold stage,
according to a fourth embodiment of the present invention;
[0035] FIG. 7 is a cross-section view for showing the conventional
coupling structure of the refrigerator; and
[0036] FIG. 8 is a view for showing an example of a thermal
contraction rate of main constituent materials (edited by Hiroyasu
HAGIWARA, "An Outline of Low Temperature Engineering", Tokyo Denki
University Publishing Office, published July, 1999, P 292).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] Hereinafter, embodiments according to the present invention
will be fully explained by referring to the attached drawings.
Embodiment 1
[0038] FIG. 1 is a cross-section view of a coupling portion of
cryogenic refrigerator, for showing a first embodiment of the
present invention.
[0039] A cryogenic refrigerator 1 is attached on a vacuum container
3, and has such a structure that an object 20 to be cooled
(hereinafter, "a cooling object 20") and a heat shield 4 are cooled
by a second cold stage 2 and a first cold stage 7. Peripheries of
the cooling object 20 and the heat shield 4 are brought in the
vacuum condition, so as to suppress an amount of heats transferring
from the vacuum container 3, which has the room temperature, to be
small. When maintaining the cryogenic refrigerator 1, it is
necessary to separate the second cold stage 4 of the cryogenic
refrigerator 1 and the cooling object 20, from the contact surface
thereof, and the first cold stage 7 and the heat shield 4 from the
contact surface thereof, respectively. In that instance, since the
periphery of the cryogenic refrigerator 1 is changed from the
vacuum condition to the atmospheric pressure, a vacuum wall 31 is
provided surrounding the cryogenic refrigerator 1. Parts of the
cooling object 20 and the heat shield 4 are also utilized as a part
of the vacuum container 3.
[0040] The cryogenic refrigerator 1 is, for example, the GM type
refrigerator, and has the first cold stage 7 and the second cold
stage 2 for generating cold. The first cold stage 7 is cooled down
between 30K and 80K. Also, the second cold stage 2 is cooled down
to 30K, or lower than that.
[0041] The cooling object, which is cooled on the first cold stage
7 of the cryogenic refrigerator 1 is mainly the heat shield 4. This
heat shield 4 receives radiation from the vacuum container 3 at the
room temperature. For reducing an amount of radiation received by
the heat shield 4, a heat insulating material, such as, so-called a
laminated heat insulating material, not shown in the figure, is
provided between the heat shield 4 and the vacuum container 3. The
heat shield 4 is utilized, for example, as a thermal anchor for a
current reed, not shown in the figure, and is also applied for
suppressing the heat transfer to be small, transferring from the
current reed to the cooling object.
[0042] On the second cold stage 2 of the cryogenic refrigerator 1,
cooling is made on the cooling object 20, which operates under the
cryogenic temperature environment. The cooling object 20 is, for
example, a superconducting magnet or equipment applying SQID
therein. This can be also applied other equipments utilizing the
cryogenic temperature environment.
[0043] The cooling object 20, which is cooled on the second cold
stage of the cryogenic refrigerator 1, has a coupling portion 21,
and cools the cooling object 20 down to the cryogenic temperature
through cooling the coupling portion 21 on the second cold stage 2
of the cryogenic refrigerator 1.
[0044] The heat shield 4, which is cooled on the first cold stage 7
of the cryogenic refrigerator 1, has a coupling portion 72, and is
able to cool the heat shield 4 down to the cryogenic temperature
through cooling the coupling portion 72 on the first cold stage 7
of the cryogenic refrigerator 1.
[0045] The cryogenic refrigerator 1 is fixed on the vacuum
container 3. The vacuum container 3 is able to bring an inside
thereof into a vacuum condition, i.e., an air inside is discharged
to vacuum by a vacuum pump not shown in the figure. The surrounding
of the cryogenic refrigerator 1 defines an enclosed space 32,
different from a vacuum tank surrounding the cooling object 20, by
a vacuum wall 31 functioning as a partition. When removing, the
cryogenic refrigerator 1 is removed while brining the enclosed
space 32 into the atmospheric pressure. In this instance, the
enclosed space 32 is filled up with the helium gas, and thereby
preventing it from condensation/forming dew within the cryogenic
temperature portion.
[0046] On the second cold stage 2 are coupled, thermally, at least
a flexible portion 11 at one (1) place and a thermal or heat
contact portion 12 with the cooling object . In the similar manner,
on the first cold stage are coupled, thermally, at least a flexible
portion 71 at one (1) place and a coupling portion 72, being the
heat contact portion with the cooling object. The flexible portions
11 and 71 are made from a material having high thermal
conductivity, such as, oxygen free copper or high purity aluminum,
etc., for example. The flexible portions 11 and 71 are made up, by
combining or bundling stranded wires of oxygen free copper or high
purity aluminum, for example, and has high thermal conductivity, as
well as, high flexibility.
[0047] The heat contact portion 12 and the heat contact portion 72
are manufactured from copper or aluminum, having high thermal
conductivity. The heat contact portion 12 and the flexible portion
72 are coupled with, thermally. In the similar manner, the heat
contact portion 72 and the flexible portion 71 are coupled with,
thermally.
[0048] On outer periphery of the heat contact portion 12 is
provided a heat contracting ring 5. Also, on outer periphery of the
heat contact portion 72 is provided a heat contracting ring 51.
Both the heat contracting rings 5 and the heat contact portion 72
are manufacture from fluoro-resin, such as, Teflon.RTM., etc., or a
high molecular compound (a high-polymer), such as, Nylon.RTM.,
etc., for example. And, on the heat contracting rings 5 and 51 are
provided heaters 6 and 61, respectively, neighboring therewith. By
means of the heat contracting ring 51, the heat contact portion 72
and a coupling portion 91 are fasten tightly.
[0049] By referring to FIG. 2, explanation will be made on the
function of each element when attaching the refrigerator, about the
second cold stage of the cryogenic refrigerator 1. FIG. 2 is a
detailed cross-section view of the coupling structure of the
cryogenic refrigerator on the second cold stage, according to the
first embodiment.
[0050] The second cold stage 2 is thermally couple with the heat
contact portion 12, through at least a part of the flexible portion
11. The heat contact portion 12 has the structure of being divided
in the peripheral direction thereof, and each of the heat contact
portions divided has the structure of being movable in a radial
direction thereof. On outer periphery of the heat contact portion
12 are provided the heat contracting ring 5 and the heater 6. The
heat contact portion 12 and the heat contracting ring 5 are so
shaped that they are coupled with, thermally, at least in a part of
the heat contact portions, which are divided in the peripheral
direction.
[0051] Such designing is made that a certain clearance can be
produced between the heat contact portion 12, which is thermally
coupled with the second cold stage 2 through the flexible portion
11, and the coupling portion 21, when the heat contact portion 12
is in the condition of the room temperature . Accordingly, under
the condition that the cryogenic refrigerator 1 at the room
temperature is attached thereon, the heat contact portion 12 on the
second cold stage and the coupling portion 21 are in the condition
of non-contact with, and therefore no movement of heats is
generated directing from the cold stage 2 at the room temperature
to the coupling portion 21.
[0052] After attaching the cryogenic refrigerator 1 thereon, if
lowering the temperature of the second cold stage 2, gradually, by
operating the cryogenic refrigerator 1, the temperature of the heat
contact portion 12, which is thermally coupled with the second cold
stage 2, is also lowered down, gradually. And also, the temperature
of the heat contracting ring 5, which is attached on the outer
periphery of the heat contact portion 12, is lowered down.
[0053] The heat contracting ring 5 is larger in the thermal
contraction rate than the heat contact portion 12 of the second
cold stage, in particular, when it is cooled down to the cryogenic
temperature. FIG. 8 is a view for showing a relationship between
volumes of thermal contraction rates of main constituent materials
(extraction from "An Outline of Low Temperature Engineering" edited
by Hiroyasu HAGIWARA, Tokyo Denki University Publishing Office,
published July, 1999, P 292).
[0054] For example, in case where the heat contact portion is made
of copper, it contracts by 0.3% under the condition of being cooled
down to about 50K, comparing to that when it is at the room
temperature; but on the contrary, where the heat contracting ring 5
or 51 is made of nylon, it contracts by 1.4% under the condition of
being cooled down to 50K, comparing to that at the room
temperature, and where it is made of Teflon.RTM., it contracts by
2.0% under the condition of being cooled down to 50K, comparing to
that at the room temperature.
[0055] Although the heat contact portion 12 thermally contracts
accompanying with lowering down of the temperature thereof, but
since the volume of the heat contraction of the heat contracting
ring 5 is larger than that of the heat contact portion 12, the heat
contracting ring 5 fastens the heat contact portion 12 tight,
gradually. Accompanying with this heat contact, the movement of
heats is produced, directing from the cryogenic refrigerator 1 to
the cooling object 20, if the temperature of the cryogenic
refrigerator 1 is high; however, since the cryogenic refrigerator 1
is in contact with, thermally, under the condition of being fully
cooled down, the volume of the heat movement is small, and it is
possible to suppress an increase of temperature of the cooling
object 20 to be small.
[0056] Next, by referring to FIGS. 1 and 2, explanation will be
given on a process for removing or detaching the refrigerator.
[0057] For separating the coupling portion 21 under the cryogenic
temperature condition from the second cold stage 2 of the cryogenic
refrigerator 1, the heater 6 attached on the outer periphery of the
heat contracting ring 5 is heated up. Because of an increase of
temperature of the heat contracting ring 5, the volume of heat
contraction of the heat contracting ring 5 comes to be small, and
therefore a clearance is generated between the heat contact portion
12 and the coupling portion 21, which are fastened tight by the
heat contracting ring 5. In the similar manner, for separating the
coupling portion 91 under the cryogenic temperature condition from
the first cold stage 7 of the cryogenic refrigerator 1, the heater
61 attached on the outer periphery of the heat contracting ring 5
is heated up. Because of an increase of temperature of the heat
contracting ring 51, the volume of heat contraction of the heat
contracting ring 51 comes to be small, and therefore a clearance is
generated between the heat contact portion 72 and the coupling
portion 91, which are fastened tight by the heat contracting ring
51.
[0058] At the time-point when the clearances are generated on both
the first cold stage 7 and the second cold stage 2 of the cryogenic
refrigerator 1, the cryogenic refrigerator 1 can be removed
from.
[0059] FIGS. 3A and 3B are cross-section views when seeing a heat
transfer means on the second cold stage 2, i.e., the heat contact
portion 12 and the heat contracting ring 5, from the above. The
heat contact portion 12 is divided in the peripheral direction
thereof. The heat contact portion 12 is in contact with the
coupling portion 21 locating at a center thereof. On the outer
periphery of the heat contact portion 12 are provided the heat
contracting ring 5 and the heater 6.
[0060] FIG. 3A shows the positional relationship between the heat
contact portion 12 and the coupling portion 21 of the cooling
object before cooling the cold stages of the cryogenic
refrigerator, i.e., under the condition of the room temperature.
Under the condition of the room temperature, there is the clearance
between the heat contact portion 12 and the coupling portion 21,
and therefore no movement of heats is produced from the heat
contact portion 12 at the room temperature to the coupling portion
21 under the condition of cryogenic temperature. Due to this, it is
possible to suppress an increase of temperature of the cooling
object when coupling the refrigerator.
[0061] FIG. 3B shows the positional relationship between the heat
contact portion 12 and the coupling portion 21 after cooling the
cold stages of the cryogenic refrigerator. By means of the second
cold stage 2 of the cryogenic refrigerator, the heat contact
portion 12, the heat contracting ring 5 and the heater 6 are cooled
down to the cryogenic temperature. The heat contracting ring 5
contracts, thermally, due to the fact of being cooled down to the
cryogenic temperature. The heat contracting ring 5 shortens a
peripheral length through the thermal contraction thereof, and it
shrinks in the radial direction. For example, in case of a ring
made of Teflon.RTM. having an inner diameter of 50 mm, the
peripheral length is shorten by 2% through the thermal contraction
down to 50K. This means that the diameter come to be small, 49 mm.
Because of shrinkage of the heat contracting ring 5 on the diameter
thereof, the heat contracting ring 5 is in the form of fastening
the heat contact portion 12, and thereby the heat contact portion
12 and the coupling portion 21 are in contact with each other,
thermally.
Embodiment 2
[0062] FIG. 4 is the detailed cross-section view of the coupling
structure of the cryogenic refrigerator on the second cold stage,
according to a second embodiment of the present invention.
Explanation will be given only on a part(s) differing from the
first embodiment mentioned above.
[0063] A heat transfer means 122 has such structure that it
supports the heat contracting ring 5 on both surfaces, e.g., from
an inner side and an outer side thereof . A sticking or closely
contacting condition is established between the heat transfer means
122 and the heat contracting ring 5, and when the temperature of
the second cold stage 2 of the cryogenic refrigerator 1 increases,
there can be produced an effect that the outer periphery of the
heat contracting ring 5 separates the heat contact portion.
Embodiment 3
[0064] FIG. 5 is the detailed cross-section view of the coupling
structure of the cryogenic refrigerator on the first cold stage,
according to a third embodiment of the present invention. By
referring to FIG. 5, explanation will be given on the coupling
structure of the cryogenic refrigerator on the first cold stage 7
of the cryogenic refrigerator 1.
[0065] The first cold stage 7 is coupled with, thermally, at least
the heat contact portion 72 through a part of the flexible portion
71. The heat contact portion 72 has the structure of being divided
in the peripheral direction thereof, and each of the heat contact
portions divided has the structure of being movable in a radial
direction. On the outer periphery are provided the heat contracting
ring 51 and the heater 61. The heat contact portion 72 and the heat
contracting portion 51 are in such form that they are coupled with,
thermally, at least a part of the heat contact portions, which are
divided in the peripheral direction.
[0066] Such designing is made that a certain clearance can be
produced between the heat contact portion 72, which is thermally
coupled with the first cold stage 7 through the flexible part 71,
and the coupling portion 91, when the heat contact portion 72 is in
the condition of the room temperature. Accordingly, under the
condition that the cryogenic refrigerator 1 at the room temperature
is attached thereon, the heat contact portion 72 on the first cold
stage and the coupling portion 91 are in the condition of
non-contact with, and therefore no movement of heats is generated
directing from the cryogenic refrigerator 1 at the room temperature
to the coupling portion 91.
[0067] After attaching the cryogenic refrigerator 1 thereon, if
lowering the temperature of the first cold stage 7, gradually, by
operating the cryogenic refrigerator 1, the temperature of the heat
contact portion 72, which is thermally coupled with the first cold
stage 2, is also lowered down, gradually. And also, the temperature
of the heat contracting ring 51, which is attached on the outer
periphery of the heat contact portion 72, is lowered down.
[0068] The heat contracting ring 51 is larger in the thermal
contraction rate than the heat contact portion 72 of the first cold
stage, in particular, when it is cooled down to the cryogenic
temperature. Although the heat contact portion 72 thermally
contracts accompanying with lowering down of the temperature
thereof, but since the volume of the heat contraction of the heat
contracting ring 51 is larger than that of the heat contact portion
72, the heat contracting ring 51 fastens the heat contact portion
72 tight, gradually. Accompanying with this heat contact, the
movement of heats is produced, directing from the cryogenic
refrigerator 1 to the heat shield 4, if the temperature of the
cryogenic refrigerator 1 is high; however, since the cryogenic
refrigerator 1 is in contact with, thermally, under the condition
of being fully cooled down, the volume of the heat movement is
small, and it is possible to suppress an increase of temperature of
the heat shield to be small.
[0069] Next, similarly, by referring to FIG. 5, explanation will be
given on a process for removing or detaching the refrigerator.
[0070] For separating the coupling portion 71 under the cryogenic
temperature condition from the first cold stage 7 of the cryogenic
refrigerator 1, the heater 61 attached on the outer periphery of
the heat contracting ring 51 is heated up. Because of an increase
of temperature of the heat contracting ring 51, the volume of heat
contraction of the heat contracting ring 51 comes to be small, and
therefore a clearance is generated between the heat contact portion
72 and the coupling portion 91, which are fastened tight by the
heat contracting ring 51. In the similar manner, for separating the
coupling portion 91 under the cryogenic temperature condition from
the first cold stage 7 of the cryogenic refrigerator 1, the heater
61 attached on the outer periphery of the heat contracting ring 5
is heated up. Because of an increase of temperature of the heat
contracting ring 51, the volume of heat contraction of the heat
contracting ring 51 comes to be small, and therefore a clearance is
generated between the heat contact portion 72 and the coupling
portion 91, which are fastened tight by the heat contracting ring
51. At the time-point when the clearances are generated on both the
first cold stage and the second cold stage of the cryogenic
refrigerator, the cryogenic refrigerator 1 can be removed from.
Embodiment 4
[0071] FIG. 6 is the detailed cross-section view of the coupling
structure of the cryogenic refrigerator on the first cold stage 7,
according to a fourth embodiment of the present invention.
[0072] A heat transfer means 78 has such structure that it supports
the heat contracting ring 51 on both surfaces, e.g., from an inner
side and an outer side thereof. A sticking or closely adhering
condition can be established between the heat transfer means 78 and
the heat contracting ring 51, and when the temperature of the first
cold stage 7 of the cryogenic refrigerator 1 increases, there can
be produced an effect that the outer periphery of the heat
contracting ring 51 separates the heat contact portion 78.
[0073] However, the present invention should not be restricted to
the embodiments mentioned above, but may includes various
modifications. For example, the embodiments mentioned above are
explained in details thereof for the purpose of easy understanding
of the present invention, but should not be limited, necessarily,
to that having all the constituent elements explained in the above.
Also, it is possible to replace a part(s) of the constituent
elements of a certain embodiment by the constituent elements of
other embodiment, or to add the constituent elements of other
embodiment to the constituent elements of a certain embodiment.
And, it is also possible to add/delete/replace other constituent
element(s), with respect to a part of the constituent elements of
each embodiment.
[0074] Also, with each structure, function, processing portion,
processing means, etc., which are mentioned above, a part or all of
those may be achieved by, for example, hardware, through designing
an integrated circuit, or so on. Or, each structure or function
mentioned above may be achieved by software, through interpreting a
program for achieving the respective functions by a processor, for
example. Information of the program, a table(s) or a file(s), etc.,
for achieving each function, may be disposed in a recording device,
such as, a memory, a hard disk, or a SSD (Solid Stage Drive), or on
a recording medium, such as, an IC card, a SD card, a DVD, etc.
[0075] The present invention may be embodied in other specific
forms without departing from the spirit or essential feature or
characteristics thereof. The present embodiment(s) is/are therefore
to be considered in all respects as illustrative and not
restrictive, the scope of the invention being indicated by the
appended claims rather than by the forgoing description and range
of equivalency of the claims are therefore to be embraces
therein.
* * * * *