U.S. patent application number 11/628656 was filed with the patent office on 2007-10-25 for cooling box.
Invention is credited to Wei Chen, Mizuho Fukaya, Hiroshi Tatsumi.
Application Number | 20070245747 11/628656 |
Document ID | / |
Family ID | 35786095 |
Filed Date | 2007-10-25 |
United States Patent
Application |
20070245747 |
Kind Code |
A1 |
Fukaya; Mizuho ; et
al. |
October 25, 2007 |
Cooling Box
Abstract
The controller of a cooling box is configured such that when the
temperature of the warm head of a Stirling refrigerating machine
exceeds a reference temperature, it maximizes the speed of a heat
radiation fan and the output of a circulation pump, and minimizes
the output of the Stirling refrigerating machine. If the
temperature of the warm head exceeds a critical temperature even
after this control, it stops the Stirling refrigerating machine.
Therefore, as compared with the case of stopping the Stirling
refrigerating machine immediately after the temperature of the warm
head has exceeded the critical temperature, the reliability of the
cooling box can be improved.
Inventors: |
Fukaya; Mizuho; (Yao-shi,
JP) ; Chen; Wei; (Chiryu-shi, JP) ; Tatsumi;
Hiroshi; (Shiki-gun, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
35786095 |
Appl. No.: |
11/628656 |
Filed: |
July 7, 2005 |
PCT Filed: |
July 7, 2005 |
PCT NO: |
PCT/JP05/12556 |
371 Date: |
December 6, 2006 |
Current U.S.
Class: |
62/6 |
Current CPC
Class: |
F25D 11/00 20130101;
F25D 29/00 20130101; F25D 21/04 20130101; F25B 9/14 20130101 |
Class at
Publication: |
062/006 |
International
Class: |
F25B 9/14 20060101
F25B009/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 29, 2004 |
JP |
2004-221611 |
Claims
1. A cooling box incorporating a Stirling refrigerating machine,
comprising: temperature detection means for detecting a temperature
of a warm head of said Stirling refrigerating machine; and control
means for controlling such that an increase of the temperature of
said warm head is restricted before stopping of said Stirling
refrigerating machine, in response to the event that a detected
temperature of said temperature detection means has exceeded a
predetermined reference temperature.
2. The cooling box according to claim 1, further comprising: a heat
radiator receiving hot heat from the warm head of said Stirling
refrigerating machine via a refrigerant and performing heat
radiation to an environment outside the box; and a heat radiation
fan promoting the heat radiation of said heat radiator, wherein
said control means is adapted to maximize the quantity of air
supplied by said heat radiation fan in response to the event that
the detected temperature of said temperature detection means has
exceeded said reference temperature, and thereafter, reduce an
output of said Stirling refrigerating machine when the detected
temperature of said temperature detection means does not become
lower than said reference temperature even after a lapse of a
predetermined time.
3. The cooling box according to claim 1, further comprising a
refrigerant circulation circuit transmitting hot heat of said warm
head via a refrigerant to an outer wall surface of the box to
prevent condensation, wherein said control means is adapted to
maximize the quantity of the refrigerant circulated in said
refrigerant circulation circuit in response to the event that the
detected temperature of said temperature detection means has
exceeded said reference temperature, and thereafter, reduce an
output of said Stirling refrigerating machine when the detected
temperature of said temperature detection means does not become
lower than said reference temperature even after a lapse of a
predetermined time.
4. The cooling box according to claim 1, further comprising: a heat
radiator receiving hot heat from the warm head of said Stirling
refrigerating machine via a refrigerant and performing heat
radiation to an environment outside the box; a heat radiation fan
promoting the heat radiation of said heat radiator; and a
refrigerant circulation circuit transmitting the hot heat of said
warm head via the refrigerant to an outer wall surface of the box
to prevent condensation, wherein said control means is adapted to
maximize the quantity of air supplied by said heat radiation fan in
response to the event that the detected temperature of said
temperature detection means has exceeded said reference
temperature, and thereafter, maximize the quantity of the
refrigerant circulated in said refrigerant circulation circuit when
the detected temperature of said temperature detection means does
not become lower than said reference temperature even after a lapse
of a first predetermined time, and further, reduce an output of
said Stirling refrigerating machine when the detected temperature
of said temperature detection means does not become lower than said
reference temperature even after a lapse of a second predetermined
time.
5. The cooling box according to claim 1, further comprising: a heat
radiator receiving hot heat from the warm head of said Stirling
refrigerating machine via a refrigerant and performing heat
radiation to an environment outside the box; a heat radiation fan
promoting the heat radiation of said heat radiator; and a
refrigerant circulation circuit transmitting the hot heat of said
warm head via the refrigerant to an outer wall surface of the box
to prevent condensation, wherein said control means is adapted to
maximize the quantity of the refrigerant circulated in said
refrigerant circulation circuit in response to the event that the
detected temperature of said temperature detection means has
exceeded said reference temperature, and thereafter, maximize the
quantity of air supplied by said heat radiation fan when the
detected temperature of said temperature detection means does not
become lower than said reference temperature even after a lapse of
a first predetermined time, and further, reduce an output of said
Stirling refrigerating machine when the detected temperature of
said temperature detection means does not become lower than said
reference temperature even after a lapse of a second predetermined
time.
6. The cooling box according to claim 1, wherein said control means
reduces the output of said Stirling refrigerating machine in a
stepwise manner.
Description
TECHNICAL FIELD
[0001] The present invention relates to a cooling box, and
particularly to a cooling box incorporating a Stirling
refrigerating machine.
BACKGROUND ART
[0002] In recent years, adverse effects of the chlorofluorocarbons
on the global environment have been pointed out, and as a cooling
box that does not use the chlorofluorocarbons, one provided with a
Stirling refrigerating machine has attracted attention. In this
cooling box, the space inside the box is cooled by cold heat of the
cold head of the Stirling refrigerating machine, while hot heat of
the warm head of the Stirling refrigerating machine is radiated to
the environment outside the box (see, for example, Japanese Patent
Laying-Open No. 2002-221384).
[0003] Patent Document 1: Japanese Patent Laying-Open No.
2002-221384
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0004] In such a cooling box, if the temperature of the warm head
of the Stirling refrigerating machine increases by some reason to
reach a critical temperature, it may be possible to stop the
Stirling refrigerating machine immediately. With this control
method, however, the operation of the cooling box will be stopped
abruptly, which leads to impairment of reliability of the cooling
box.
[0005] Accordingly, a primary object of the present invention is to
provide a cooling box of high reliability.
Means for Solving the Problems
[0006] A cooling box according to the present invention is a
cooling box incorporating a Stirling refrigerating machine, which
includes: temperature detection means for detecting a temperature
of a warm head of the Stirling refrigerating machine; and control
means for controlling such that an increase of the temperature of
the warm head is restricted before the Stirling refrigerating
machine is stopped, in response to the event that the temperature
detected by the temperature detection means has exceeded a
predetermined reference temperature.
[0007] Preferably, a heat radiator receiving hot heat from the warm
head of the Stirling refrigerating machine via a refrigerant and
performing heat radiation to an environment outside the box; and a
heat radiation fan promoting the heat radiation of the heat
radiator are further provided. The control means maximizes the
quantity of air supplied by the heat radiation fan in response to
the event that the temperature detected by the temperature
detection means has exceeded the reference temperature and,
thereafter, reduces an output of the Stirling refrigerating machine
when the temperature detected by the temperature detection means
does not become lower than the reference temperature even after a
lapse of a predetermined time.
[0008] Further, preferably, a refrigerant circulation circuit
transmitting the hot heat of the warm head to an outer wall surface
of the box via the refrigerant to prevent condensation is further
provided. The control means maximizes the quantity of the
refrigerant circulated in the refrigerant circulation circuit in
response to the event that the temperature detected by the
temperature detection means has exceeded the reference temperature
and, thereafter, reduces an output of the Stirling refrigerating
machine when the temperature detected by the temperature detection
means does not become lower than the reference temperature even
after a lapse of a predetermined time.
[0009] Further, preferably, a heat radiator receiving hot heat from
the warm head of the Stirling refrigerating machine via a
refrigerant and performing heat radiation to an environment outside
the box; a heat radiation fan promoting the heat radiation of the
heat radiator; and a refrigerant circulation circuit transmitting
the hot heat of the warm head to an outer wall surface of the box
via the refrigerant to prevent condensation are further provided.
The control means maximizes the quantity of air supplied by the
heat radiation fan in response to the event that the temperature
detected by the temperature detection means has exceeded the
reference temperature and, thereafter, maximizes the quantity of
the refrigerant circulated in the refrigerant circulation circuit
when the temperature detected by the temperature detection means
does not become lower than the reference temperature even after a
lapse of a first predetermined time, and reduces an output of the
Stirling refrigerating machine when the temperature detected by the
temperature detection means does not become lower than the
reference temperature even after a lapse of a second predetermined
time.
[0010] Further, preferably, a heat radiator receiving hot heat from
the warm head of the Stirling refrigerating machine via a
refrigerant and performing heat radiation to an environment outside
the box; a heat radiation fan promoting the heat radiation of the
heat radiator; and a refrigerant circulation circuit transmitting
the hot heat of the warm head to an outer wall surface of the box
via the refrigerant to prevent condensation are further provided.
The control means maximizes the quantity of the refrigerant
circulated in the refrigerant circulation circuit in response to
the event that the temperature detected by the temperature
detection means has exceeded the reference temperature and,
thereafter, maximizes the quantity of air supplied by the heat
radiation fan when the temperature detected by the temperature
detection means does not become lower than the reference
temperature even after a lapse of a first predetermined time, and
reduces an output of the Stirling refrigerating machine when the
temperature detected by the temperature detection means does not
become lower than the reference temperature even after a lapse of a
second predetermined time.
[0011] Preferably, the control means reduces the output of the
Stirling refrigerating machine in a stepwise manner in response to
the event that the temperature detected by the temperature
detection means has exceeded the reference temperature.
[0012] Still preferably, the control means stops the Stirling
refrigerating machine in response to the event that the temperature
detected by the temperature detection means has exceeded a
predetermined critical temperature higher than the reference
temperature.
[0013] Still preferably, the cooling box further includes
inspection means for inspecting whether the temperature detection
means is normal or not in response to the event that the
temperature detected by the temperature detection means has
exceeded the reference temperature.
Effects of the Invention
[0014] In the cooling box of the present invention, it is
controlled to restrict an increase in temperature of the warm head
of the Stirling refrigerating machine before stopping the Stirling
refrigerating machine in response to the event that the temperature
of the warm head has exceeded a reference temperature. Accordingly,
it is possible to prevent the cooling box from being stopped
abruptly, and thus to increase the reliability of the cooling
box.
[0015] Preferably, the quantity of the air supplied by the heat
radiation fan is maximized in response to the event that the
temperature of the warm head has exceeded the reference
temperature, and thereafter, if the temperature of the warm head
does not become lower than the reference temperature even after a
lapse of a predetermined time, the output of the Stirling
refrigerating machine is reduced. In this case, the temperature of
the warm head can firstly be lowered without increasing the
temperature inside the box. This can increase the reliability of
the cooling box.
[0016] Still preferably, the quantity of the refrigerant circulated
in the refrigerant circulation circuit is maximized in response to
the event that the temperature of the warm head has exceeded the
reference temperature, and thereafter, if the temperature of the
warm head does not become lower than the reference temperature even
after a lapse of a predetermined time, the output of the Stirling
refrigerating machine is reduced. In this case as well, the
temperature of the warm head can firstly be lowered without
increasing the temperature inside the box, and thus, the
reliability of the cooling box can be increased.
[0017] Still preferably, the quantity of the air supplied by the
heat radiation fan is maximized in response to the event that the
temperature of the warm head has exceeded the reference
temperature, and thereafter, if the temperature of the warm head
does not become lower than the reference temperature even after a
lapse of a first predetermined time, the quantity of the
refrigerant circulated in the refrigerant circulation circuit is
maximized, and further, if the temperature of the warm head does
not become lower than the reference temperature even after a lapse
of a second predetermined time, the output of the Stirling
refrigerating machine is reduced. In this case as well, the
temperature of the warm head can firstly be lowered without
increasing the temperature inside the box, and thus, the
reliability of the cooling box can be increased.
[0018] Still preferably, the quantity of the refrigerant circulated
in the refrigerant circulation circuit is maximized in response to
the event that the temperature of the warm head has exceeded the
reference temperature, and thereafter, if the temperature of the
warm head does not become lower than the reference temperature even
after a lapse of a first predetermined time, the quantity of the
air supplied by the heat radiation fan is maximized, and further,
if the temperature of the warm head does not become lower than the
reference temperature even after a lapse of a second predetermined
time, the output of the Stirling refrigerating machine is reduced.
In this case as well, the temperature of the warm head can firstly
be lowered without increasing the temperature inside the box, and
thus, the reliability of the cooling box can be increased.
[0019] Preferably, the output of the Stirling refrigerating machine
is reduced in a stepwise manner. This can restrict the increase in
temperature inside the box.
[0020] Still preferably, the Stirling refrigerating machine is
stopped in response to the event that the temperature of the warm
head has exceeded a critical temperature higher than the reference
temperature. This can prevent a failure of the Stirling
refrigerating machine.
[0021] Still preferably, there is further provided inspection means
for inspecting whether the temperature detection means is normal or
not in response to the event that the temperature detected by the
temperature detection means has exceeded the reference temperature.
This can prevent malfunction of the cooling box due to a failure of
the temperature detection means.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a cross sectional view showing a configuration of
a cooling box according to an embodiment of the present
invention.
[0023] FIG. 2 is a piping configuration diagram of the cooling box
shown in FIG. 1.
[0024] FIG. 3 is a block diagram showing a configuration of a part
related to operation control of the cooling box shown in FIG.
1.
[0025] FIG. 4 is a part of a flowchart showing an operation of the
controller shown in FIG. 3.
[0026] FIG. 5 is the other part of the flowchart shown in FIG.
4.
DESCRIPTION OF THE REFERENCE SIGNS
[0027] 1: cooling box; 10: housing; 11, 12, 13: cooling
compartment; 14, 15, 16: heat insulating door; 17: packing; 18:
shelf; 19: machine room; 20: duct; 21: cool air blowoff port; 22:
cooling fan; 30: Stirling refrigerating machine; 40:
low-temperature side refrigerant circulation circuit; 41:
low-temperature side condenser; 42: low-temperature side
evaporator; 50, 60: high-temperature side refrigerant circulation
circuit; 51: high-temperature side evaporator, 52: high-temperature
side condenser; 53: heat radiation fan; 61: circulation pump; 62:
condensation preventing section; 70: electric heater; 80: box
interior temperature sensor; 81: cold head temperature sensor; 82:
warm head temperature sensor; 83: inspection section; 84: reference
value storage section; 85: alarm lamp; 86: controller; and 87:
timer 87.
BEST MODE FOR CARRYING OUT THE INVENTION
[0028] FIG. 1 is a schematic cross sectional view showing a
configuration of a cooling box 1 according to an embodiment of the
present invention. FIG. 2 is a piping configuration diagram of
cooling box 1. Referring to FIGS. 1 and 2, cooling box 1 is for
storing food, and is provided with a housing 10 of heat insulating
structure. Cooling compartments 11, 12, 13 partitioned into three
parts in the vertical direction are provided inside housing 10.
Cooling compartments 11, 12, 13 have openings on the front side
(left side in FIG. 1) of housing 10, and the openings are closed by
heat insulating doors 14, 15, 16, respectively, which can be
opened/closed freely. A packing 17 is provided on the back surface
of each of heat insulating doors 14, 15, 16, in the form
surrounding the opening of corresponding one of cooling boxes 11,
12, 13. Inside cooling compartments 11, 12, 13, shelves 18 are
arranged as appropriate in accordance with the types of food to be
stored.
[0029] A cooling system and a heat radiation system having Stirling
refrigerating machine 30 as the main element are arranged from the
top surface through the back surface to the bottom surface of
housing 10. A machine room 19 is provided at a corner on the upper
back surface of housing 10, and Stirling refrigerating machine 30
is installed therein.
[0030] A part of Stirling refrigerating machine 30 forms a cold
head when driven. A low-temperature side condenser 41 is attached
to the cold head. Further, a low-temperature side evaporator 42 is
arranged on the back of cooling box 13. Low-temperature side
condenser 41 and low-temperature side evaporator 42 are connected
via a refrigerant pipe, to constitute a low-temperature side
refrigerant circulation circuit 40. Low-temperature side
refrigerant circulation circuit 40 has a natural refrigerant such
as CO.sub.2 sealed therein, and heat is given and received by
low-temperature side evaporator 42 and low-temperature side
condenser 41.
[0031] A duct 20 is provided inside housing 10 for distributing
cool air obtained by low-temperature side evaporator 42 to cooling
compartments 11, 12, 13. Duct 20 has cool air blowoff ports 21 at
appropriate positions for communication with cooling compartments
11, 12, 13. Further, cooling fans 22 are arranged inside duct 20 at
appropriated positions to forcibly send out the cool air.
[0032] Although not shown in the figure, a duct for collecting the
air from cooling compartments 11, 12, 13 is provided inside housing
10. The duct has a blowoff port at the bottom of low-temperature
side evaporator 42, to supply low-temperature side evaporator 42
with the air to be cooled, as shown by an arrow of broken line in
FIG. 1.
[0033] Another part of Stirling refrigerating machine 30 forms a
warm head when driven. A high-temperature side evaporator 51 is
attached to the warm head. Further, at the upper surface of housing
10, a high-temperature side condenser (heat radiator) 52 and a heat
radiation fan 53 are provided for performing heat radiation to the
environment outside the box. High-temperature side evaporator 51
and high-temperature side condenser 52 are connected via a
refrigerant pipe, to constitute a high-temperature side refrigerant
circulation circuit 50. High-temperature side refrigerant
circulation circuit 50 has water (including solution) or
hydrocarbon-based natural refrigerant sealed therein, and the
refrigerant flows within high-temperature side refrigerant
circulation circuit 50 by natural circulation.
[0034] High-temperature side evaporator 51 is connected to a
high-temperature side refrigerant circulation circuit 60 as well.
High-temperature side refrigerant circulation circuit 60 has a
circulation pump 61 forcibly circulating the refrigerant, and a
condensation preventing section 62. Circulation pump 61 may be a
piezoelectric pump, for example. Condensation preventing section 62
is formed with a part of the refrigerant pipe routed through the
openings of cooling compartments 11, 12, 13, and is configured to
heat the vicinity of the openings where condensation would likely
to occur (the vicinity of the contact portions of packing 17 and
housing 10, i.e., the boundary area between the interior and the
outside of the box) with the hot heat of the refrigerant to thereby
prevent condensation. An electric heater 70 generating heat when
energized is attached to the place where occurrence of condensation
is expected but high-temperature side refrigerant circulation
circuit 60 cannot be placed for the reasons of manufacture.
[0035] Hereinafter, an operation of cooling box 1 having the above
configuration will be described. In cooling box 1 configured as
described above, when Stirling refrigerating machine 30 is driven,
the temperature of the cold head decreases. Thus, low-temperature
side condenser 41 is cooled, and the refrigerant therein is
condensed.
[0036] The refrigerant condensed at low-temperature side condenser
41 flows through low-temperature side refrigerant circulation
circuit 40 into low-temperature side evaporator 42. The refrigerant
flowing into low-temperature side evaporator 42 evaporates with the
heat of the air flowing along the outer side of low-temperature
side evaporator 42, to thereby reduce the surface temperature of
low-temperature side evaporator 42. Thus, the air flowing through
low-temperature side evaporator 42 becomes cool air, which is blown
into cooling compartments 11, 12, 13 via cool air blowoff ports 21
of duct 20, so that the temperatures in cooling compartments 11,
12, 13 are lowered. Thereafter, the air within cooling compartments
11, 12, 13 returns to low-temperature side evaporator 42 via a duct
not shown.
[0037] The refrigerant evaporated at low-temperature side
evaporator 42 returns via low-temperature side refrigerant
circulation circuit 40 to low-temperature side condenser 41, where
it condenses again with its heat deprived. The above-described heat
exchange operation is repeated.
[0038] Meanwhile, the heat produced by driving of Stirling
refrigerating machine 30 and the heat collected from the interior
of the box by the cold head are dissipated from the warm head as
exhaust heat. Thus, high-temperature side evaporator 51 is heated,
and the refrigerant therein evaporates.
[0039] The refrigerant in the gas phase heated at high-temperature
side evaporator 51 flows through high-temperature side refrigerant
circulation circuit 50 and enters into high-temperature side
condenser 52 provided on the top. The refrigerant flowing into
high-temperature side condenser 52 condenses as its heat is
deprived by the airflow introduced from the exterior of the box
into high-temperature side condenser 52 by heat radiation fan 53.
The refrigerant condensed at high-temperature side condenser 52
flows through high-temperature side refrigerant circulation circuit
50 back to high-temperature side evaporator 51, where it evaporates
again by receiving the heat. The above-described heat exchange
operation is repeated.
[0040] Of the refrigerant saturated inside high-temperature side
evaporator 51, the refrigerant in the liquid phase is forcibly
circulated by circulation pump 61 to high-temperature side
refrigerant circulation circuit 60, and is guided to condensation
preventing section 62. Thus, the vicinity of the openings of
cooling compartments 11, 12, 13 is heated with the hot heat of the
introduced refrigerant. With the configuration described above, the
temperature in the vicinity of the openings where condensation
would likely occur can be kept at a level not lower than the dew
point to prevent condensation, without unnecessary consumption of
electric power. At the portion where occurrence of condensation is
expected but high-temperature side refrigerant circulation circuit
60 cannot be routed, electric heater 70 is applied with
electricity, so that the temperature at the portion can be kept at
a level not lower than the dew point to thereby prevent
condensation.
[0041] FIG. 3 is a block diagram showing a portion of cooling box 1
related to operation control. In FIG. 3, cooling box 1 includes a
box interior temperature sensor 80, a cold head temperature sensor
81, a warm head temperature sensor 82, an inspection section 83, a
reference value storage section 84, an alarm lamp 85, and a
controller 86. Controller 86 includes a timer 87.
[0042] Box interior temperature sensor 80 is arranged at a
prescribed position on a surface of duct 20 on the box interior
side, for example, and detects the temperature of the space inside
the box and provides a signal indicating the detected value to
controller 86. Cold head temperature sensor 81 is provided at the
cold head of Stirling refrigerating machine 30, and detects the
temperature of the cold head and provides a signal indicating the
detected value to controller 86. Warm head temperature sensor 82 is
provided at the warm head of Stirling refrigerating machine 30, and
detects the temperature Th of the warm head and provides a signal
indicating the detected value to controller 86.
[0043] Inspection section 83 carries out an inspection as to
whether warm head temperature sensor 82 is normal or not, and
provides a signal indicating the result of inspection to controller
86. Reference value storage section 84 is formed of a read only
memory such as a ROM, and stores a reference temperature of the
space inside the box, a reference temperature of the cold head, a
reference temperature Th1 of the warm head, and a critical
temperature Th2 of the warm head.
[0044] Alarm lamp 85 is provided on the external surface of heat
insulating door 14, for example, and turns on when cooling box 1
fails to operate properly to notify the user of the failure of
cooling box 1. Controller 86 controls Stirling refrigerating
machine 10, heat radiation fan 53, circulation pump 61 and alarm
lamp 85 based on various kinds of information from temperature
sensors 80-82, inspection section 83 and reference value storage
section 84.
[0045] FIGS. 4 and 5 are flowcharts illustrating an operation of
controller 86. Controller 86 controls the output of Stirling
refrigerating machine 10 such that the detected values of
temperature sensors 80-82 coincide with the reference values stored
in reference value storage section 84, and also controls the
rotation speed of heat radiation fan 53, i.e., the quantity of air
supplied thereby. Controller 86 further controls the output of
circulation pump 61, i.e., the quantity of the refrigerant
circulated in high-temperature side refrigerant circulation circuit
60.
[0046] Further, in step S1, controller 86 determines whether the
temperature Th of the warm head is higher than the reference
temperature Th1 stored in reference value storage section 84, and
if it is not Th>Th1, it carries out step S1 again. If Th>Th1,
it proceeds to step S2. In step S2, controller 86 causes inspection
section 83 to carry out an inspection as to whether warm head
temperature sensor 82 is normal or not. Inspection section 83
checks whether warm head temperature sensor 82 is normal or not,
and provides a signal indicating the result of inspection to
controller 86.
[0047] In step S3, controller 86 determines whether warm head
temperature sensor 82 is normal or not based on the signal from
inspection section 83, and if warm head temperature sensor 82 is
not normal, it performs temperature sensor abnormality notification
processing in step S4, such as turning on of alarm lamp 85, while
it proceeds to step S5 if it is normal.
[0048] In step S5, controller 86 determines whether the rotation
speed of heat radiation fan 53 is maximum or not, and if it is not
maximum, it maximizes the rotation speed of heat radiation fan 53
in step S6. In step S7, it awaits a lapse of a predetermined time,
and then proceeds to step S12. If the rotation speed of heat
radiation fan 53 is maximum, it proceeds to step S8. Timer 87 is
used to count the predetermined time.
[0049] In step S8, controller 86 determines whether the output of
circulation pump 61 is maximum or not, and if it is not maximum, it
maximizes the output of circulation pump 61 in step S9. In step
S10, it awaits a lapse of a predetermined time, and then proceeds
to step S12. If the output of circulation pump 61 is maximum, it
reduces the output of Stirling refrigerating machine 30 in step
S11, and then proceeds to step S12. In step S11, controller 86
reduces the output of Stirling refrigerating machine 30 from the
current value to the minimum value stepwise over a plurality of
number of times.
[0050] In step S12, controller 86 determines whether temperature Th
of the warm head is higher than reference temperature Th1 stored in
reference value storage section 84, and if Th>Th1 does not hold,
it returns to step S1. If Th>Th1, it proceeds to step S13. In
step S13, controller 86 determines whether the output of Stirling
refrigerating machine 30 is minimum or not. If it is not minimum,
it returns to step S8. If it is minimum, it proceeds to step
S14.
[0051] In step S14, controller 86 determines whether temperature Th
of the warm head is higher than critical temperature Th2 stored in
reference value storage section 84. If Th>Th2 does not hold, it
returns to step S8. If Th>Th1, it proceeds to step S15.
[0052] In step S15, controller 86 performs the warm head
abnormality display processing, such as turning on of alarm lamp 85
or the like. In step S16, it stops Stirling refrigerating machine
30, and returns to step S1.
[0053] In the present embodiment, when temperature Th of the warm
head exceeds reference temperature Th1, the rotation speed of heat
radiation fan 53 is maximized, the output of circulation pump 61 is
maximized, and the output of Stirling refrigerating machine 30 is
minimized. If temperature Th of the warm head still exceeds
critical temperature Th2, Stirling refrigerating machine 30 is
stopped. As such, compared to the case where Stirling refrigerating
machine 30 is stopped immediately after temperature Th of the warm
head exceeds critical temperature Th2, the reliability of cooling
box 1 can be increased.
[0054] Although the rotation speed of heat radiation fan 53 has
been maximized after maximization of the output of circulation pump
61 in the present embodiment, it is possible to maximize the output
of heat radiation fan 53 after maximization of the output of
circulation pump 61.
[0055] It should be understood that the embodiments disclosed
herein are illustrative and non-restrictive in every respect. The
scope of the present invention is defined by the terms of the
claims, rather than the description and example above, and is
intended to include any modifications and changes within the scope
and meaning equivalent to the terms of the claims.
* * * * *