U.S. patent application number 14/646653 was filed with the patent office on 2015-11-26 for refrigeration device for container.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. The applicant listed for this patent is DAIKIN INDUSTRIES, LTD.. Invention is credited to Kiichirou SATOU, Akitoshi UENO.
Application Number | 20150338135 14/646653 |
Document ID | / |
Family ID | 50775832 |
Filed Date | 2015-11-26 |
United States Patent
Application |
20150338135 |
Kind Code |
A1 |
SATOU; Kiichirou ; et
al. |
November 26, 2015 |
REFRIGERATION DEVICE FOR CONTAINER
Abstract
A blown air temperature sensor detects a temperature of blown
air which is being blown into a container after having passed
sequentially through an evaporator and a heating device. During
cooling and dehumidifying operations, a temperature control section
controls a cooling section such that a detected blown air
temperature detected by the blown air temperature sensor becomes
equal to a target temperature. A target control section sets the
target temperature to be a first preset temperature which is equal
to a preset inside temperature when the cooling operation is
performed, and sets the target temperature to be a second preset
temperature which is sum of the preset inside temperature and a
target increment temperature once a switch has been made from the
cooling operation to the dehumidifying operation.
Inventors: |
SATOU; Kiichirou; (Osaka,
JP) ; UENO; Akitoshi; (Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIKIN INDUSTRIES, LTD. |
Osaka-shi, Osaka |
|
JP |
|
|
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka-shi, Osaka
JP
|
Family ID: |
50775832 |
Appl. No.: |
14/646653 |
Filed: |
November 22, 2013 |
PCT Filed: |
November 22, 2013 |
PCT NO: |
PCT/JP2013/006892 |
371 Date: |
May 21, 2015 |
Current U.S.
Class: |
62/228.1 |
Current CPC
Class: |
F25D 17/042 20130101;
F25D 2400/02 20130101; F25B 49/02 20130101; F25D 29/003 20130101;
G05D 23/1931 20130101; F25D 2700/14 20130101; F25D 2317/04111
20130101; F25B 13/00 20130101; F25B 2400/13 20130101; F25D 11/003
20130101 |
International
Class: |
F25B 13/00 20060101
F25B013/00; F25B 49/02 20060101 F25B049/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 22, 2012 |
JP |
2012-256856 |
Claims
1. A container refrigeration device comprising: a cooling section
having a refrigerant circuit which includes a compressor, a
condenser, an expansion mechanism, and an evaporator that are
sequentially connected together, and through which a refrigerant
circulates, and a heating device provided downstream of the
evaporator with respect to a direction in which sucked air that has
been sucked from an inside of a container flows, the cooling
section configured to allow the sucked air to pass sequentially
through the evaporator and the heating device, and then, to be
blown into the inside of the container, the container refrigeration
device configured to perform a cooling operation in which the
heating device is at rest and the sucked air is cooled by the
evaporator, and a dehumidifying operation in which the sucked air
is cooled and dehumidified by the evaporator and then heated by the
heating device, wherein the container refrigeration device further
includes a blown air temperature sensor configured to detect a
temperature of blown air which is being blown into the inside of
the container after having passed sequentially through the
evaporator and the heating device, a temperature control section
configured to control, during the cooling and dehumidifying
operations, the cooling section such that a detected blown air
temperature which is a temperature of the blown air detected by the
blown air temperature sensor becomes equal to a predetermined
target temperature, and a target control section, where the target
control section sets, during the cooling operation, the target
temperature to be a first preset temperature which is equal to a
preset inside temperature that has been determined in advance with
respect to an inside temperature of the container, and once a
switch has been made from the cooling operation to the
dehumidifying operation, the target control section sets the target
temperature to be a second preset temperature which is the sum of
the preset inside temperature and a predetermined target increment
temperature.
2. The container refrigeration device of claim 1, further
comprising: a sucked air temperature sensor configured to detect a
temperature of the sucked air, wherein after a switch has been made
from the cooling operation to the dehumidifying operation, the
target control section lowers the target temperature if a detected
sucked air temperature which is the temperature of the sucked air
detected by the sucked air temperature sensor becomes higher than a
predetermined reference sucked air temperature, and raises the
target temperature if the detected sucked air temperature becomes
lower than the reference sucked air temperature.
3. The container refrigeration device of claim 2, wherein the
reference sucked air temperature is set to be a stabilized sucked
air temperature which is the temperature of the sucked air detected
by the sucked air temperature sensor when the cooling operation is
in a stabilized state, or to be a preset sucked air temperature
which is the sum of the preset inside temperature and a
predetermined sucked air increment temperature.
4. The container refrigeration device of claim 1, wherein the
target control section corrects, during the dehumidifying
operation, the target temperature in accordance with dehumidifying
capacity of the evaporator such that the target temperature rises
as the dehumidifying capacity of the evaporator increases.
5. The container refrigeration device of claim 2, wherein the
target control section corrects the target temperature such that
the target temperature becomes equal to or higher than the preset
inside temperature.
6. The container refrigeration device of claim 1, wherein the
heating device is implemented as a reheat heat exchanger into which
part of the refrigerant discharged from the compressor flows during
the dehumidifying operation.
7. The container refrigeration device of claim 6, further
comprising: an operation control section configured to perform a
first dehumidifying control or a second dehumidifying control when
the dehumidifying operation is being performed, wherein the first
dehumidifying control is performed to allow part of the refrigerant
discharged from the compressor to flow into the reheat heat
exchanger, and the second dehumidifying control is performed to
allow part of the refrigerant discharged from the compressor to
flow into the reheat heat exchanger and to control the cooling
section such that a discharge pressure of the compressor becomes
higher during the second dehumidifying control than during the
first dehumidifying control.
8. The container refrigeration device of claim 1, wherein the
heating device is implemented as an electric heater.
9. The container refrigeration device of claim 8, further
comprising: an operation control section configured to perform a
first dehumidifying control or a second dehumidifying control when
the dehumidifying operation is being performed, wherein the first
dehumidifying control is performed to drive the electric heater,
and the second dehumidifying control is performed to drive the
electric heater with the heating capacity of the electric heater
set to be higher than the heating capacity during the first
dehumidifying control.
10. The container refrigeration device of claim 2, wherein the
target control section corrects, during the dehumidifying
operation, the target temperature in accordance with dehumidifying
capacity of the evaporator such that the target temperature rises
as the dehumidifying capacity of the evaporator increases.
11. The container refrigeration device of claim 3, wherein the
target control section corrects, during the dehumidifying
operation, the target temperature in accordance with dehumidifying
capacity of the evaporator such that the target temperature rises
as the dehumidifying capacity of the evaporator increases.
12. The container refrigeration device of claim 3, wherein the
target control section corrects the target temperature such that
the target temperature becomes equal to or higher than the preset
inside temperature.
13. The container refrigeration device of claim 4, wherein the
target control section corrects the target temperature such that
the target temperature becomes equal to or higher than the preset
inside temperature.
14. The container refrigeration device of claim 2, wherein the
heating device is implemented as a reheat heat exchanger into which
part of the refrigerant discharged from the compressor flows during
the dehumidifying operation.
15. The container refrigeration device of claim 3, wherein the
heating device is implemented as a reheat heat exchanger into which
part of the refrigerant discharged from the compressor flows during
the dehumidifying operation.
16. The container refrigeration device of claim 4, wherein the
heating device is implemented as a reheat heat exchanger into which
part of the refrigerant discharged from the compressor flows during
the dehumidifying operation.
17. The container refrigeration device of claim 5, wherein the
heating device is implemented as a reheat heat exchanger into which
part of the refrigerant discharged from the compressor flows during
the dehumidifying operation.
18. The container refrigeration device of claim 2, wherein the
heating device is implemented as an electric heater.
19. The container refrigeration device of claim 3, wherein the
heating device is implemented as an electric heater.
20. The container refrigeration device of claim 4, wherein the
heating device is implemented as an electric heater.
Description
TECHNICAL FIELD
[0001] The present invention relates to a container refrigeration
device (a refrigeration device for container), and in particular,
to a measure for preventing chilling injury.
BACKGROUND ART
[0002] Container refrigeration devices have been used in the art to
cool the inside of containers for marine transportation and other
purposes. Patent Document 1 describes a container refrigeration
device equipped with a refrigerant circuit which includes a
compressor, a condenser, a receiver, an electronic expansion valve,
and an evaporator that are sequentially connected together. This
container refrigeration device further includes a heat exchanger
for heating (a heating device) which is provided on the leeward
side of the evaporator in the refrigerant circuit. The heat
exchanger for heating is configured to allow a gaseous refrigerant
discharged from the compressor to flow therethrough. The container
refrigeration device performs, in a switchable manner, a cooling
operation in which the air that has been sucked from inside of the
container is cooled by the evaporator, and a dehumidifying
operation in which the air that has been sucked from inside of
container is cooled and dehumidified by the evaporator, and then,
heated by the heat exchanger for heating.
CITATION LIST
[0003] PATENT DOCUMENT 1: Japanese Unexamined Patent Publication
No. H11-63769
SUMMARY OF THE INVENTION
Technical Problem
[0004] Meanwhile, in the container refrigeration device as
described above, the air that has been sucked from inside of the
container passes through the evaporator and the heating device (for
example, the heat exchanger for heating), and then, is blown back
into the inside of the container through an air outlet extending in
the width direction inside of the container. A blown air
temperature sensor for detecting the temperature of the air that is
being blown through the air outlet (i.e., blown air) is provided at
a point of the air outlet. During each of the cooling operation and
the dehumidifying operation, temperature control is performed such
that the temperature of the blown air detected by the blown air
temperature sensor (hereinafter referred to as a "detected blown
air temperature") becomes equal to a predetermined preset inside
temperature.
[0005] While the container refrigeration device as described above
is performing the dehumidifying operation, however, the air passing
through the heating device (i.e., the air that has been subjected
to cooling and dehumidification in the evaporator) may not be
uniformly heated with respect to the width direction inside of the
container. For example, if the refrigerant which is present in the
heat exchanger for heating has a non-uniform temperature
distribution with respect to the width direction inside of the
container, the air passing through the heat exchanger for heating
is no longer heated uniformly with respect to the width direction
inside of the container. Consequently, the air being blown out of
the heat exchanger for heating has non-uniformity in temperature,
as shown in FIG. 11. In such a case, once a switch is made from the
cooling operation to the dehumidifying operation, it becomes
difficult for the blown air temperature sensor to detect accurately
the lowest temperature of the blown air with respect to the width
direction inside of the container. Specifically, when the
dehumidifying operation is being performed, the detected blown air
temperature may be higher than the actual lowest temperature of the
blown air with respect to the width direction inside of the
container. Therefore, even if temperature control is performed
during the dehumidifying operation such that the detected blown air
temperature becomes equal to the preset inside temperature, the
lowest temperature of the blown air with respect to the width
direction inside of the container may become lower than the preset
inside temperature, and consequently, may cause a load inside the
container chilling injury.
[0006] It is therefore an object of the present invention to
provide a container refrigeration device capable of preventing
causing chilling injury to a load inside the container.
Solution to the Problem
[0007] A first aspect of the present invention relates to a
container refrigeration device including a cooling section (18)
having: a refrigerant circuit (16) which includes a compressor
(21), a condenser (23), an expansion mechanism (76), and an
evaporator (25) that are sequentially connected together, and
through which a refrigerant circulates; and a heating device (17)
provided downstream of the evaporator (25) with respect to a
direction in which sucked air that has been sucked from an inside
of a container (C) flows. The cooling section (18) is configured to
allow the sucked air to pass sequentially through the evaporator
(25) and the heating device (17), and then, to be blown into the
inside of the container (C). The container refrigeration device is
configured to perform a cooling operation in which the heating
device (17) is at rest and the sucked air is cooled by the
evaporator (25), and a dehumidifying operation in which the sucked
air is cooled and dehumidified by the evaporator (25) and then
heated by the heating device (17). The container refrigeration
device further includes a blown air temperature sensor (34)
configured to detect a temperature of blown air which is being
blown into the inside of the container (C) after having passed
sequentially through the evaporator (25) and the heating device
(17). The container refrigeration device further includes a
temperature control section (101) configured to control, during the
cooling and dehumidifying operations, the cooling section (18) such
that a detected blown air temperature (Tss) which is a temperature
of the blown air detected by the blown air temperature sensor (34)
becomes equal to a predetermined target temperature (Tx). The
container refrigeration device further includes a target control
section (201). During the cooling operation, the target control
section (201) sets the target temperature (Tx) to be a first preset
temperature which is equal to a preset inside temperature (Tsp)
that has been determined in advance with respect to an inside
temperature of the container (C). Once a switch has been made from
the cooling operation to the dehumidifying operation, the target
control section (201) sets the target temperature (Tx) to be a
second preset temperature which is the sum of the preset inside
temperature (Tsp) and a predetermined target increment
temperature.
[0008] According to the first aspect of the present invention, a
cooling operation and a dehumidifying operation are performed.
During each operation, a refrigerant circuit (16) of a cooling
section (18) performs a refrigeration cycle in which a refrigerant
discharged from a compressor (21) condensed by a condenser (23),
expanded by an expansion mechanism (76), and then evaporated by an
evaporator (25). During the cooling operation, sucked air that has
been sucked from the inside of a container (C) exchanges heat with
a refrigerant that is flowing through the evaporator (25) and is
cooled, while flowing through the evaporator (25). During the
cooling operation, a target control section (201) sets a target
temperature (Tx) to be a first preset temperature that is equal to
the preset inside temperature (Tsp). Therefore, during the cooling
operation, a temperature control section (101) controls the cooling
section (18) such that the detected blown air temperature (Tss)
becomes equal to the first preset temperature that is equal to the
preset inside temperature (Tsp).
[0009] In addition, according to the first aspect of the present
invention, if a switch has been made from the cooling operation to
the dehumidifying operation, the sucked air that has been sucked
from inside of the container (C) exchanges, in the evaporator (25),
heat with the refrigerant that is flowing through the evaporator
(25) and is cooled to cause condensation (that is to say, the
sucked air is cooled and dehumidified). Thereafter, when passing
through a heating device (17), the sucked air is heated by the
heating device (17). The target control section (201) sets the
target temperature (Tx) to be a second preset temperature that is
the sum of the preset inside temperature (Tsp) and a target
increment temperature. Therefore, if a switch is made from the
cooling operation to the dehumidifying operation, the temperature
control section (101) controls the cooling section (18) such that
the detected blown air temperature (Tss) becomes equal to the
second preset temperature that is the sum of the preset inside
temperature (Tsp) and the target increment temperature.
[0010] During the dehumidifying operation, the air passing through
the heating device (17) (i.e., the air that has been cooled and
dehumidified by the evaporator (25)) may not be uniformly heated
with respect to the width direction inside of the container (C). In
this case, the blown air that is being blown into the inside of the
container (C) after having passed through the evaporator (25) and
the heating device (17) may have non-uniformity in temperature, and
consequently, the detected blown air temperature (Tss) may be
higher than the lowest temperature of the blown air with respect to
the width direction inside of the container (C). Thus, even if a
temperature control is performed such that the detected blown air
temperature (Tss) becomes equal to the preset inside temperature
(Tsp) during the dehumidifying operation, the lowest temperature of
the blown air with respect to the width direction inside of the
container (C) may still become lower than the preset inside
temperature (Tsp).
[0011] To address this problem, according to the first aspect of
the present invention, once a switch has been made from the cooling
operation to the dehumidifying operation, the target temperature
(Tx) is set to be the second preset temperature (i.e., the sum of
the preset inside temperature (Tsp) and the target increment
temperature) that is higher than the preset inside temperature
(Tsp). Therefore, the temperature of the blown air that is being
blown into the inside of the container (C) can be raised on
average. Consequently, the temperature of the blown air can also be
raised with respect to the width direction inside of the container
(C). As a result, even if the air that is passing through the
heating device (17) is heated non-uniformly with respect to the
width direction inside of the container (C), the lowest temperature
of the blown air with respect to the width direction inside of the
container (C) is not allowed to become lower than the preset inside
temperature (Tsp).
[0012] A second aspect of the present invention is an embodiment of
the container refrigeration device according to the first aspect,
and further includes a sucked air temperature sensor (33)
configured to detect a temperature of the sucked air. According to
the second aspect, after a switch has been made from the cooling
operation to the dehumidifying operation, the target control
section (201) lowers the target temperature (Tx) if a detected
sucked air temperature (Trs) which is the temperature of the sucked
air detected by the sucked air temperature sensor (33) becomes
higher than a predetermined reference sucked air temperature, and
raises the target temperature (Tx) if the detected sucked air
temperature (Trs) becomes lower than the reference sucked air
temperature.
[0013] According to the second aspect of the present invention, the
air which has passed through the evaporator (25) and the heating
device (17) and has been blown into the inside of the container (C)
circulates inside of the container (C) and is sucked again into the
evaporator (25). Accordingly, a variation in the detected sucked
air temperature (Trs) depends on a variation in the inside
temperature of the container (C). Specifically, as the inside
temperature of the container (C) rises, the temperature of sucked
air also rises, which results in an increase in the detected sucked
air temperature (Trs). Conversely, as the inside temperature of the
container (C) falls, the temperature of sucked air also fails,
which results in a decrease in the detected sucked air temperature
(Trs). The target control section (201) corrects the target
temperature (Tx) in accordance with the variation in the detected
sucked air temperature (Trs) which has been caused after a switch
has been made from the cooling operation to the dehumidifying
operation. Specifically, if the inside temperature of the container
(C) rises, after the switch from the cooling operation to the
dehumidifying operation, so much that the detected sucked air
temperature (Trs) becomes higher than the reference sucked air
temperature, the target control section (201) lowers the target
temperature (Tx). This leads to a decrease in the temperature of
the blown air, and eventually, a decrease in the inside temperature
of the container (C). On the other hand, if the inside temperature
of the container (C) falls, after the switch from the cooling
operation to the dehumidifying operation, so much that the detected
sucked air temperature (Trs) becomes lower than the reference
sucked air temperature, then the target control section (201)
raises the target temperature (Tx). This leads to an increase in
the temperature of the blown air, and eventually, an increase in
the inside temperature of the container (C). Thus, by controlling
the temperature of the blown air in accordance with such a
variation in the detected sucked air temperature (Trs)
(specifically, the results of comparison between the detected
sucked air temperature (Trs) and the reference sucked air
temperature) after the switch from the cooling operation to the
dehumidifying operation, a variation in the inside temperature of
the container (C), involved with the switch from the cooling
operation to the dehumidifying operation, can be reduced.
[0014] A third aspect of the present invention is an embodiment of
the container refrigeration device according to the second aspect.
According to the third aspect, the reference sucked air temperature
is set to be a stabilized sucked air temperature (Trs) which is the
temperature of the sucked air detected by the sucked air
temperature sensor (33) when the cooling operation is in a
stabilized state, or to be a preset sucked air temperature which is
the sum of the preset inside temperature (Tsp) and a predetermined
sucked air increment temperature.
[0015] According to the third aspect of the present invention,
after the switch from the cooling operation to the dehumidifying
operation, the target control section (201) lowers the target
temperature (Tx) if the detected sucked air temperature (Trs)
becomes higher than the stabilized sucked air temperature (Trs) (or
the preset sucked air temperature). On the other hand, the target
control section (201) raises the target temperature (Tx) if the
detected sucked air temperature (Trs) becomes lower than the
stabilized sucked air temperature (Trs) (or the preset sucked air
temperature). Thus, by reference to the stabilized sucked air
temperature (Trs) or the preset sucked air temperature, a
determination can be made whether or not any variation has been
caused in the detected sucked air temperature (Trs) due to a
variation in the inside temperature of the container (C) after the
switch from the cooling operation to the dehumidifying
operation.
[0016] A fourth aspect of the present invention is an embodiment of
the container refrigeration device according to any one of the
first to third aspects. According to the fourth aspect, during the
dehumidifying operation, the target control section (201) corrects
the target temperature (Tx) in accordance with dehumidifying
capacity of the evaporator (25) such that the target temperature
(Tx) rises as the dehumidifying capacity of the evaporator (25)
increases.
[0017] According to the fourth aspect of the present invention, the
evaporator (25) cools the air and causes the air to condense,
thereby dehumidifying the air. Specifically, during the
dehumidifying operation, the temperature of the blown air tends to
fall more easily as the dehumidifying capacity (the cooling
capacity) of the evaporator (25) increases. Therefore, the target
temperature (Tx) is corrected in accordance with the dehumidifying
capacity of the evaporator (25) during the dehumidifying operation
such that the target temperature (Tx) rises as the dehumidifying
capacity of the evaporator (25) increases, thereby raising the
temperature of the blown air if the temperature of the blown air
tends to fall easily during the dehumidifying operation.
[0018] A fifth aspect of the present invention is an embodiment of
the container refrigeration device according to any one of the
second to fourth aspects. According to the fifth aspect, the target
control section (201) corrects the target temperature (Tx) such
that the target temperature (Tx) becomes equal to or higher than
the preset inside temperature (Tsp).
[0019] According to the fifth aspect of the present invention, the
lower limit of the target temperature (Tx) is set to be the preset
inside temperature (Tsp). This can prevent the temperature of the
blown air from falling excessively, and consequently, the inside
temperature of the container (C) from falling excessively.
[0020] A sixth aspect of the present invention is an embodiment of
the container refrigeration device according to any one of the
first to fifth aspects. According to the sixth aspect, the heating
device (17) is implemented as a reheat heat exchanger (32) into
which part of the refrigerant discharged from the compressor (21)
flows during the dehumidifying operation.
[0021] According to the sixth aspect of the present invention,
during the dehumidifying operation, part of the refrigerant
discharged from the compressor (21) flows into the reheat heat
exchanger (32), whereas the rest of the refrigerant circulates
through the refrigerant circuit (16), and then, enters the
evaporator (25). The air that is passing through the evaporator
(25) is cooled by exchanging heat with the refrigerant that is
flowing through the evaporator (25), and condensation occurs (i.e.,
the air is cooled and dehumidified). On the other hand, air that is
passing through the reheat heat exchanger (32) is heated by
exchanging heat with the refrigerant that is flowing through the
reheat heat exchanger (32). In this manner, during the
dehumidifying operation, the sucked air that has been sucked from
inside of the container (C) can be cooled and dehumidified by the
evaporator (25), and then heated by the reheat heat exchanger
(32).
[0022] A seventh aspect of the present invention is an embodiment
of to the container refrigeration device of the sixth aspect, and
further includes an operation control section (105) configured to
perform a first dehumidifying control or a second dehumidifying
control when the dehumidifying operation is being performed.
According the seventh aspect, the first dehumidifying control is
performed to allow part of the refrigerant discharged from the
compressor (21) to flow into the reheat heat exchanger (32),
whereas the second dehumidifying control is performed to allow part
of the refrigerant discharged from the compressor (21) to flow into
the reheat heat exchanger (32) and to control the cooling section
(18) such that a discharge pressure of the compressor (21) becomes
higher during the second dehumidifying control than during the
first dehumidifying control.
[0023] According to the seventh aspect of the present invention,
first and second dehumidifying controls are performed. When the
first dehumidifying control is being performed, part of the
refrigerant discharged from the compressor (21) flows into the
reheat heat exchanger (32) whereas the rest of the refrigerant
circulates through the refrigerant circuit (16) and enters the
evaporator (25). In this manner, the sucked air that has been
sucked from inside of the container (C) can be cooled and
dehumidified by the evaporator (25), and then heated by the reheat
heat exchanger (32). When the second dehumidifying control is being
performed, on the other hand, the heating capacity of the reheat
heat exchanger (32) can be increased by controlling the cooling
section (18) such that the discharge pressure of the compressor
(21) becomes higher during the second dehumidifying control than
during the first dehumidifying control. The increase in the heating
capacity of the reheat heat exchanger (32) causes the temperature
of the blown air to rise, which makes the detected blown air
temperature (Tss) higher than the target temperature (Tx).
Therefore, the temperature control section (101) controls the
cooling section (18) to lower the detected blown air temperature
(Tss), and thereby increases the cooling capacity of the evaporator
(25). For example, the temperature control section (101) increases
the flow rate of the refrigerant that circulates through the
refrigerant circuit (16) of the cooling section (18) to increase
the cooling capacity of the evaporator (25). In this manner, the
temperature of the blown air can be lowered, and consequently, the
detected blown air temperature (Tss) can be lowered toward the
target temperature (Tx). Further, the dehumidifying capacity of the
evaporator (25) can be increased by increasing the cooling capacity
of the evaporator (25).
[0024] An eighth aspect of the present invention is an embodiment
of the container refrigeration device of any one of the first to
fifth aspects. According to the eighth aspect, the heating device
(17) is implemented as an electric heater (78).
[0025] According to the eighth aspect of the present invention,
during the dehumidifying operation, the air that is passing through
the evaporator (25) is cooled by exchanging heat with the
refrigerant that is passing through the evaporator (25), and
condensation occurs (i.e., the air is cooled and dehumidified). On
the other hand, when passing through the electric heater (78), the
air is heated by the electric heater (78). In this manner, during
the dehumidifying operation, the sucked air that has been sucked
from inside of the container (C) can be cooled and dehumidified by
the evaporator (25), and then heated by the electric heater
(78).
[0026] A ninth aspect of the present invention is an embodiment of
the container refrigeration device of the eighth aspect, and
further includes an operation control section (105) configured to
perform a first dehumidifying control or a second dehumidifying
control when the dehumidifying operation is being performed.
According to the ninth aspect, the first dehumidifying control is
performed to drive the electric heater (78), whereas the second
dehumidifying control is performed to drive the electric heater
(78) with the heating capacity of the electric heater (78) set to
be higher than the heating capacity during the first dehumidifying
control.
[0027] According to the ninth aspect of the present invention,
first and second dehumidifying controls are performed. When the
first dehumidifying control is being performed, the sucked air that
has been sucked from inside of the container (C) can be cooled and
dehumidified by the evaporator (25), and then heated by the
electric heater (78). When the second dehumidifying control is
being performed, on the other hand, the heating capacity of the
electric heater (78) is set to be higher than the capacity during
the first dehumidifying control, thereby increasing the heating
capacity of the electric heater (78). The increase in the heating
capacity of the electric heater (78) causes the temperature of the
blown air to rise, which makes the detected blown air temperature
(Tss) higher than the target temperature (Tx). Therefore, the
temperature control section (101) controls the cooling section (18)
to lower the detected blown air temperature (Tss) and thereby
increases the cooling capacity of the evaporator (25). In this
manner, the temperature of the blown air can be lowered, and
consequently, the detected blown air temperature (Tss) can be
lowered toward the target temperature (Tx). Further, the
dehumidifying capacity of the evaporator (25) can be increased by
increasing the cooling capacity of the evaporator (25).
Advantages of the Invention
[0028] According to the first aspect of the present invention, once
a switch has been made from the cooling operation to the
dehumidifying operation, the target temperature (Tx) is set to be
the second preset temperature (i.e., the sum of the preset inside
temperature (Tsp) and the target increment temperature). In this
manner, even if the air that is passing through the heating device
(17) is heated non-uniformly with respect to the width direction
inside of the container (C), the lowest temperature of the blown
air with respect to the width direction inside of the container (C)
is not allowed to become lower than the preset inside temperature
(Tsp). As a result, chilling injury to a load inside the container
(C) can be prevented.
[0029] According to the second and third aspects of the present
invention, the target temperature (Tx) is corrected in accordance
with a variation in the detected sucked air temperature (Trs) after
the switch has been made from the cooling operation to the
dehumidifying operation. This enables reduction of a variation in
the inside temperature of the container (C) involved with the
switch from the cooling operation to the dehumidifying operation.
Therefore, during the dehumidifying operation, chilling injury to a
load inside the container (C) and an increase in the inside
temperature of the container (C) can be prevented.
[0030] According to the fourth aspect of the present invention,
during the dehumidifying operation, the target temperature (Tx) is
corrected in accordance with the dehumidifying capacity of the
evaporator (25), thereby raising the temperature of the blown air
if the temperature of the blown air tends to fall easily during the
dehumidifying operation. Thus, the inside temperature of the
container (C) can be prevented from falling even if the
dehumidifying capacity rises in the evaporator (25).
[0031] According to the fifth aspect of the present invention, the
lower limit of the target temperature (Tx) is set to be the preset
inside temperature (Tsp). This can prevent the inside temperature
of the container (C) from falling excessively, thereby ensuring
that the load inside container (C) does not suffer chilling injury
during the dehumidifying operation.
[0032] According to the sixth aspect of the present invention,
during the dehumidifying operation, the sucked air that has been
sucked from inside of the container (C) can be cooled and
dehumidified by the evaporator (25), and then heated by the reheat
heat exchanger (32). Therefore, the air inside of the container (C)
can be dehumidified with the inside temperature of the container
(C) prevented from falling.
[0033] According to the seventh aspect of the present invention,
when the second dehumidifying control is being performed, the
dehumidifying capacity of the evaporator (25) can be increased by
increasing the cooling capacity of evaporator (25) as the heating
capacity of the reheat heat exchanger (32) increases such that the
detected blown air temperature (Tss) becomes equal to the target
temperature (Tx). Therefore, reduction of a variation in the inside
temperature of the container (C) and the increase in the
dehumidifying capacity of the evaporator (25) can be achieved.
[0034] According to the eighth aspect of the present invention,
during the dehumidifying operation, sucked air that has been sucked
form inside of the container (C) can be cooled and dehumidified by
the evaporator (25), and then heated by the electric heater (78).
Therefore, the air inside of the container (C) can be dehumidified
with the inside temperature of the container (C) prevented from
falling.
[0035] According to the ninth aspect of the present invention, when
the second dehumidifying control is being performed, the
dehumidifying capacity of the evaporator (25) can be increased by
increasing the cooling capacity of evaporator (25) as the heating
capacity of the electric heater (78) increases such that the
detected blown air temperature (Tss) becomes equal to the target
temperature (Tx). Therefore, reduction of a variation in the inside
temperature of the container (C) and the increase in the
dehumidifying capacity of the evaporator (25) can be achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 is a perspective view of a container refrigeration
device according to a first embodiment, as viewed from outside of
the container.
[0037] FIG. 2 is a cross-sectional view showing a configuration of
the container refrigeration device of the first embodiment.
[0038] FIG. 3 is a front view of a casing of the first embodiment,
as viewed from inside of the container.
[0039] FIG. 4 is a piping system diagram showing a cooling section
of the container refrigeration device of the first embodiment.
[0040] FIG. 5 is a state transition diagram showing a cooling
operation and a dehumidifying operation of the first
embodiment.
[0041] FIG. 6 shows first to third dehumidifying controls of the
dehumidifying operation according to the first embodiment.
[0042] FIGS. 7A and 7B show how a first correction section of the
first embodiment operates. FIG. 7A shows an example of correction
by which a target temperature is lowered. FIG. 7B shows an example
of correction by which the target temperature is raised.
[0043] FIG. 8 is a graph showing time-temperature relations during
the cooling and dehumidifying operations of the first
embodiment.
[0044] FIG. 9 is a graph showing a relation between the width
direction inside of the container and temperature during the
dehumidifying operation of the first embodiment.
[0045] FIG. 10 is a piping system diagram showing a cooling section
of a container refrigeration device of a third embodiment
[0046] FIG. 11 is a graph showing a relation between the width
direction inside of the container and temperature during a
dehumidifying operation of a conventional container refrigeration
device.
DESCRIPTION OF EMBODIMENTS
[0047] Embodiments will now be described in detail with reference
to the drawings. In the drawings, like reference characters are
used to denote identical or equivalent components, and description
thereof will not be repeated herein.
First Embodiment
[0048] As shown in FIGS. 1 to 3, a container refrigeration device
(10) according to a first embodiment is configured to refrigerate
or freeze a load inside a container (C) for use in marine
transportation, for example. The container (C) is in a box shape,
one side of which is open (or in a cylindrical shape having a
bottom). The container refrigeration device (10) is installed such
that the device closes the open end of the container (C). There is
a load (not shown) to be cooled inside the container (C). Examples
of the loads include perishable foods and precision electronic
parts.
[0049] As shown in FIG. 4, the container refrigeration device (10)
includes a controller (100), a cooling section (18) having a
refrigerant circuit (16) and a heating device (17), a sucked air
temperature sensor (33), a blown air temperature sensor (34), and a
humidity sensor (53). The refrigerant circuit (16) is a closed
circuit filled with a refrigerant. A compressor (21), a condenser
(23), an expansion valve (76), and an evaporator (25) are
sequentially connected together to form the refrigerant circuit
(16).
[0050] As shown in FIG. 2, in the cooling section (18), the heating
device (17) is provided downstream of the evaporator (25) of the
refrigerant circuit (16) with respect to the direction in which air
sucked from inside of the container (C) (i.e., sucked air) flows.
Specifically, in the cooling section (18), the sucked air passes
sequentially through the evaporator (25) and the heating device
(17), and then is blown into the inside of the container (C). In
this embodiment, the heating device (17) is implemented as a reheat
heat exchanger (32).
[0051] The container refrigeration device (10) is configured to
cool the air inside the container (C) by using the refrigeration
cycle that the refrigerant circuit (16) of the cooling section (18)
performs. Specifically, the container refrigeration device (10) of
this embodiment performs a cooling operation in which the heating
device (17) is at rest and the sucked air is cooled by the
evaporator (25), and a dehumidifying operation in which the sucked
air is cooled and dehumidified by the evaporator (25), and then,
heated by the heating device (17).
[0052] <Structure of Container Refrigeration Device>
[0053] As shown in FIGS. 1 and 2, the container refrigeration
device (10) includes a casing (11) of which the peripheral portion
is attached to the container (C) such that the open end of the
container (C) is closed. In this example, the cooling section (18)
of the container refrigeration device (10) includes, in addition to
the refrigerant circuit (16) and the heating device (17) (i.e. the
reheat heat exchanger (32), in this example), an outer fan (24), an
outer motor (45), and blower units (30).
[0054] As shown in FIG. 2, the casing (11) includes an outer casing
(12) that faces the outside of the container (C) and an inner
casing (13) that faces the inside of the container (C). The outer
casing (12) and the inner casing (13) are metallic casings of an
aluminum alloy. An insulation material (14) is provided in the
space between the outer and inner casings (12 and 13).
[0055] The outer casing (12) is attached to the open end of the
container (C) so as to close the open end. The outer casing (12)
has a lower portion protruding toward the inside of the container
(C). The inner casing (13) has been formed to run along the outer
casing (12), and its lower portion also protrudes toward the inside
of the container as well as the lower portion of the outer casing
(12). Thus, the casing (11) has its lower portion protruding toward
the inside of the container (C), and consequently, the lower
portion of the casing (11) has a recess (11a) arranged outside of
the container. That is to say, an outer storage space (S1) is
formed in the lower portion of the casing (11) so as to face the
outside of the container, and an inner storage space (S2) is formed
in the upper portion of the casing (11) so as to face the inside of
the container.
[0056] In addition, a partition plate (48) is provided closer to
the inside of the container than the casing (11) is. The partition
plate (48) which is a substantially rectangular plate member is
arranged upright so as to face the casing (11) with a gap left
between them. The inner storage space (S2) is separated by the
partition plate (48) from inside of the container (C). A gap left
between the upper edge of the partition plate (48) and the ceiling
of the container (C) serves as an air inlet (51) through which the
air inside of the container (C) is sucked into the inner storage
space (S2). A gap left between the lower edge of the partition
plate (48) and the bottom surface of the container (C) serves as an
air outlet (52) through which the air treated by the container
refrigeration device (10) (i.e., the air that has passed
sequentially through the evaporator (25) and the heating device
(17)) is blown into the inside of the container. Both lateral edges
of the partition plate (48) in the width direction inside of the
container (C) are fixed to the side surfaces of the container (C)
which define the inner width of the container.
[0057] <<Outer Storage Space>>
[0058] The outer storage space (S1) houses the compressor (21), the
condenser (23), the outer fan (24), and the outer motor (45). The
compressor (21) and the condenser (23) are connected to the
refrigerant circuit (16). The outer motor (45) rotates the outer
fan (24) that takes the air outside of the container into the outer
storage space (S1) and blows the air toward the condenser (23). The
outer motor (45) is configured to selectively start or stop
operating (start/stop) in response to a control by the controller
(100). That is to say, the start/stop of the outer fan (24) is
controlled by the controller (100). In the condenser (23), the air
sucked from outside of the container (C) exchanges heat with the
refrigerant.
[0059] <<Inner Storage Space>>
[0060] The inner storage space (S2) houses, in its upper portion
located closer to the inside of the container than the casing (11)
is, the reheat heat exchanger (32), the evaporator (25), the blower
unites (30), the sucked air temperature sensor (33), and the
humidity sensor (53). The inner storage space (S2) further houses
the blown air temperature sensor (34) in its lower portion located
closer to the inside of the container than the casing (11) is.
Specifically, in the inner storage space (S2), the sucked air
temperature sensor (33) and the humidity sensor (53) are arranged
in an upper portion closest to the air inlet (51) (i.e., in the
vicinity of the air inlet (51)). The blower units (30) are arranged
immediately under the sucked air temperature sensor (33). The
evaporator (25) is arranged immediately under the blower units
(30). The reheat heat exchanger (32) is arranged immediately under
the evaporator (25). The blown air temperature sensor (34) is
arranged in a lower portion closest to the air outlet (52) (i.e.,
in the vicinity of the air outlet (52)).
[0061] --Blower Units--
[0062] The blower units (30) blow the air inside of the container
(C) to the inner storage space (S2) (specifically, to the
evaporator (25) and the reheat heat exchanger (32)). The blower
units (30) are arranged in the upper portion of the inner storage
space (S2) and aligned side by side in the width direction of the
casing (11). Each blower unit (30) includes a fan housing (31), an
inner fan (26), and an inner motor (46). The inner motor (46)
rotates the inner fan (26) that takes in the air inside of the
container (C) through the air inlet (51) located over the partition
plate (48) and blows the air to the inner storage space (S2)
(specifically, to the evaporator (25) and reheat heat exchanger
(32)). The inner motor (46) is configured to selectively start or
stop operating (star/stop) in response to a control by the
controller (100). That is to say, the start/stop of the inner fan
(26) is controlled by the controller (100). The air (sucked air)
that the inner fans (26) have sucked from inside of the container
(C) passes sequentially through the evaporator (25) and the reheat
heat exchanger (32). Thereafter, the air is blown into the inside
of the container (C) through the air outlet (52) located under the
partition plate (48). In other words, the reheat heat exchanger
(32) is arranged downstream of the evaporator (25) with respect to
the direction in which the air sucked from inside of the container
(C) flows.
[0063] --Sucked Air Temperature Sensor--
[0064] The sucked air temperature sensor (33) is configured to
detect the temperature of the sucked air which is being sucked from
inside of the container (C) (i.e., the air which is being blown
from inside of the container (C) to the inner storage space (S2)).
In this example, the sucked air temperature sensor (33) is arranged
between the two blower units (30, 30) such that the sensor (33) is
substantially level with the top of the blower units (30). The
temperature of the sucked air detected by the sucked air
temperature sensor (33) (hereinafter, referred to as the detected
sucked air temperature (Trs)) is transmitted to the controller
(100).
[0065] --Blown Air Temperature Sensor--
[0066] The blown air temperature sensor (34) is configured to
detect the temperature of the air which is being blown into the
inside of the container (C) from the inner storage space (S2) (i.e.
the blown air). Specifically, the blown air temperature sensor (34)
is configured to detect the temperature of the blown air that is
being blown into the inside of the container (C) after having
passed sequentially through the evaporator (25) and the reheat heat
exchanger (32). In this example, the blown air temperature sensor
(34) is arranged between the lower portion of the inner storage
space (S2) (i.e., the protruding portion of the inner casing (13))
and the partition plate (48) and substantially at a middle of the
width inside of the container. The temperature of the blown air
detected by the blown air temperature sensor (34) (hereinafter,
referred to as the detected blown air temperature (Tss)) is
transmitted to the controller (100).
[0067] --Humidity Sensor--
[0068] The humidity sensor (53) is configured to detect the
humidity of the sucked air that is being sucked from inside of the
container (C). The humidity of the sucked air detected by the
humidity sensor (53) (hereinafter, referred to as the detected
sucked air humidity) is transmitted to the controller (100).
[0069] <<Other Components of Container Refrigeration
Device>>
[0070] As shown in FIG. 1, the casing (11) has two openings (27)
arranged in line side by side in the width direction near the upper
edge of the casing (11). A door (28) which is opened or closed for
doing maintenance is attached to each opening (27). In the outer
storage space (S1) of the casing (11), an electric component box
(29) is provided adjacent to the outer fan (24).
[0071] As shown in FIG. 3, in the upper portion of the casing (11),
an evaporator retainer frame (15) is provided so as to face the
inside of the container. The evaporator retainer frame (15) extends
in the width direction of the casing (11) and retains the
evaporator (25). Further, in the casing (11), side stays (40) and a
frame support member (43) are provided so as to face the inside of
the container. The side stays (40) are arranged to stand upright
near both lateral ends of the casing (11) in the width direction of
the casing (11), and connected to the lower portion of the casing
(11) protruding toward the inside of the container. The frame
support member (43) is a column member having a substantially
U-shaped cross section, and provided so as to face the inside of
the container in the lower portion of the casing (11). The frame
support member (43) vertically extends along the centerline with
respect to the width of the casing (11). The evaporator retainer
frame (15) is supported by the side stays (40) at both of the
lateral ends in the width direction and by the frame support member
(43) at the middle of the width. Specifically, the middle of the
width of the evaporator retainer frame (15) is fixed to the middle
of the width of the casing (11) to face the inside of the
container, and connected to the top end of the frame support member
(43).
[0072] <Configuration of Refrigerant Circuit>
[0073] As shown in FIG. 4, in the refrigerant circuit (16), the
compressor (21), the condenser (23), the expansion valve (76), and
the evaporator (25) are sequentially connected by means of
refrigerant pipes. In this embodiment, a high-pressure liquid pipe
(81) is provided between the condenser (23) and the expansion valve
(76). A low-pressure liquid pipe (82) is provided between the
expansion valve (76) and the evaporator (25). A low-pressure gas
pipe (83) is provided between the evaporator (25) and the
compressor (21). The outer fan (24) configured to blow the air
outside of the container (C) to the condenser (23) is provided near
the condenser (23). The inner fans (26) configured to blow the air
inside the container (C) to the evaporator (25) are provided near
the evaporator (25). The high-pressure liquid pipe (81) is provided
with the receiver (73), a first subcooling heat exchanger (60), a
first on-off valve (35), a dryer (42), and a second subcooling heat
exchanger (63), which are arranged in this order. The low-pressure
gas pipe (83) is provided with a suction proportional valve
(66).
[0074] <<Compressor>>
[0075] The compressor (21) compresses the refrigerant and
discharges the compressed refrigerant. The compressor (21) is
configured to selectively start or stop operating in response to a
control by the controller (100). In this embodiment, the compressor
(21) includes a compression mechanism (not shown) and a compressor
motor (not shown) for driving the compression mechanism. The
compressor motor has a constant revolution speed. That is to say,
the compressor motor is configured to operate at the constant
revolution speed
[0076] <<Condenser>>
[0077] The condenser (23) is configured to allow the refrigerant
discharged from the compressor (21) to flow into itself, and to
cause the refrigerant that has flowed into itself to dissipate heat
into the air (i.e., the air outside of the container, in this
example) which is passing through the condenser (23), thereby
allowing the refrigerant to condense. In other words, in the
condenser (23), the refrigerant flowing through the condenser (23)
exchanges heat with the air passing through condenser (23), and
consequently, the refrigerant flowing through the condenser (23) is
allowed to condense, while the air passing through the condenser
(23) is heated. For example, the condenser (23) may be a heat
exchanger which includes circular heat transfer tubes (a so-called
fin-and-tube heat exchanger of a cross fin tube type).
[0078] <<Receiver>>
[0079] The receiver (73) is provided downstream of the condenser
(23) with respect to the direction in which the refrigerant flows
(i.e., the direction in which the refrigerant flows in the
refrigerant circuit (16)). The receiver (73) is configured to
separate the refrigerant that has flowed into itself from the
condenser (23) into a saturated liquid and a saturated gas, and to
make the saturated liquid flow out. For example, the receiver (73)
may be implemented as an elongated cylindrical hermetic vessel.
[0080] <<First Subcooling Heat Exchanger>>
[0081] The first subcooling heat exchanger (60) includes a first
high-pressure side channel (61) and a first low-pressure side
channel (62). The first high-pressure side channel (61) of the
first subcooling heat exchanger (60) is provided downstream of the
receiver (73) with respect to the direction of in which the
refrigerant flows.
[0082] <<First On-Off Valve>>
[0083] The first on-off valve (35) is configured to regulate the
flow rate of the refrigerant which is flowing through the
high-pressure liquid pipe (81) between the dryer (42) and the
expansion valve (76). The opening degree of the first on-off valve
(35) is adjustable in response to a control by the controller
(100).
[0084] <<Dryer>>
[0085] The dryer (42) is provided downstream of the first on-off
valve (35) with respect to the direction in which the refrigerant
flows. The dryer (42) is configured to capture the moisture
contained in the liquid refrigerant which has flowed out of the
condenser (23) (in this embodiment, the liquid refrigerant which
has passed through the receiver (73), the first subcooling heat
exchanger (60), and the first on-off valve (35)).
[0086] <<Second Subcooling Heat Exchanger>>
[0087] The second subcooling heat exchanger (63) includes a second
high-pressure side channel (64) and a second low-pressure side
channel (65). The second high-pressure side channel (64) of the
second subcooling heat exchanger (63) is provided downstream of the
dryer (42) with respect to the direction in which the refrigerant
flows.
[0088] <<Expansion Valve (Expansion Mechanism)>>
[0089] The expansion valve (76) is configured to expand and
decompress the refrigerant which is flowing inside itself. The
opening degree of the expansion valve (76) is adjustable in
response to a control by the controller (100).
[0090] <<Evaporator>>
[0091] The evaporator (25) is configured to allow the refrigerant
which has flowed out of the expansion valve (76) (and entered the
low-pressure liquid pipe (82), in this example) to flow into
itself. The evaporator (25) is configured to cool the air
(specifically, the sucked air that has been sucked from inside of
the container (C)) which is passing through the evaporator (25) by
allowing the refrigerant that has entered the evaporator (25) to
absorb heat from the air. In other words, in the evaporator (25),
the refrigerant flowing through the evaporator (25) exchanges heat
with the air passing through the evaporator (25), and consequently,
the refrigerant flowing through the evaporator (25) evaporates,
while the air passing through the evaporator (25) is cooled. For
example, the evaporator (25) is a heat exchanger which includes
circular heat transfer tubes (i.e., a so-called fin-and-tube heat
exchanger of a cross fin tube type). The heat transfer tubes of the
evaporator (25) extend in the width direction inside of the
container (C).
[0092] <<Suction Proportional Valve>>
[0093] The suction proportional valve (66) is configured to
regulate the flow rate of the refrigerant which circulates through
the refrigerant circuit (16). The opening degree of the suction
proportional valve (66) is adjustable in response to the control by
the controller (100). That is to say, the refrigerant circuit (16)
is configured to regulate, in response to the control by the
controller (100), the flow rate of the refrigerant that
circulates.
[0094] <<First Branch Pipe>>
[0095] A first branch pipe (85) is connected to a halfway point of
the high-pressure gas pipe (80). Part of the refrigerant that flows
through the high-pressure gas pipe (80) enters the first branch
pipe (85). Further, first and second connection pipes (91, 92)
branch off from the first branch pipe (85). In other words, the
first branch pipe (85) has one end connected to the halfway point
of the high-pressure gas pipe (80).
[0096] <<First to Third Connection Pipes>>
[0097] The first connection pipe (91), of which one end is
connected to the other end of the first branch pipe (85), has the
other end connected to a halfway point of the low-pressure liquid
pipe (82). The first connection pipe (91) is provided with a heater
solenoid valve (71). The second connection pipe (92), of which one
end is connected to the other end of the first branch pipe (85),
has the other end connected to a halfway point of the low-pressure
liquid pipe (82). The second connection pipe (92) is provided with
a reheat solenoid valve (70) and the reheat heat exchanger (32)
that are arranged in this order. A third connection pipe (93) is
connected to a halfway point of the first connection pipe (91)
(specifically, a point between the other end of the first
connection pipe (91) connected to the low-pressure liquid pipe (82)
and the heater solenoid valve (71)). The third connection pipe
(93), of which one end is connected to the halfway point of the
first connection pipe (91), has the other end connected to a
halfway point of the low-pressure liquid pipe (82). The third
connection pipe (93) is provided with a drain pan heater (77).
[0098] <<Heater Solenoid Valve and Reheat Solenoid
Valve>>
[0099] The reheat solenoid valve (70) and the heater solenoid valve
(71) are each configured so that its opening degree is adjustable
in repose to a control by the controller (100). The flow rates of
the refrigerant in the first and third connection pipes (91 and 93)
are regulated by adjusting the opening degree of the heater
solenoid valve (71). The flow rate of the refrigerant in the second
connection pipe (92) is regulated by adjusting the opening degree
of the reheat solenoid valve (70). The heater solenoid valve (71)
is switched into an open state when the drain pan heater (77) is
activated.
[0100] <<Drain Pan Heater>>
[0101] The drain pan heater (77) is configured to heat a drain pan
(not shown) which receives the water that has condensed in the
evaporator (25), and to melt the ice that has formed in the drain
pan. The drain pan heater (77) is configured such that the
refrigerant discharged from the compressor (21) (i.e., hot gas)
flows into the drain pan heater (77).
[0102] <<Reheat Heat Exchanger>>
[0103] During the dehumidifying operation, part of the refrigerant
discharged from the compressor (21) flows into the reheat heat
exchanger (32). The reheat heat exchanger (32) heats the air which
is passing through itself (specifically, the air which has been
cooled and dehumidified by the evaporator (25)) by allowing the
refrigerant that has entered the reheat heat exchanger (32) to
dissipate its heat into the air. In other words, during the
dehumidifying operation, the reheat heat exchanger (32) allows the
refrigerant flowing through the reheat heat exchanger (32) to
exchange heat with the air passing through the reheat heat
exchanger (32), and consequently, the refrigerant flowing through
the reheat heat exchanger (32) condenses, while the air passing
through the reheat heat exchanger (32) is heated. For example, the
reheat heat exchanger (32) may be implemented as a heat exchanger
which includes circular heat transfer tubes (the so-called
fin-and-tube heat exchanger of a cross fin tube type). The heat
transfer tubes of the reheat heat exchanger (32) extend in the
width direction inside of the container (C). The refrigerant which
has flowed out of the reheat heat exchanger (32) enters the
low-pressure liquid pipe (82).
[0104] <<Second Branch Pipe>>
[0105] Further, a second branch pipe (86) is connected to a halfway
point of the high-pressure liquid pipe (81) (specifically, a point
between the first subcooling heat exchanger (60) and the first
on-off valve (35)). Part of the refrigerant that flows through the
high-pressure liquid pipe (81) enters the second branch pipe (86).
The second branch pipe (86), of which one end is connected to the
halfway point of the high-pressure liquid pipe (81), has the other
end connected to an intermediate port communicating with a
compression chamber which has an intermediate pressure and which
forms part of the compressor (21). The second branch pipe (86) is
provided with a second on-off valve (36), a capillary tube (39),
the second low-pressure side channel (65) of the second subcooling
heat exchanger (63), and the first low-pressure side channel (62)
of the first subcooling heat exchanger (60), which are arranged in
this order.
[0106] <<Second on-Off Valve>>
[0107] The second on-off valve (36) is configured to regulate the
flow rate of the refrigerant flowing through the second branch pipe
(86). The opening degree of the second on-off valve (36) is
adjustable in response to a control by the controller (100). The
second on-off valve (36) is switched into an open state when the
first and second subcooling heat exchangers (60, 63) subcool the
refrigerant. The second on-off valve (36) is switched into a closed
state when the first and second subcooling heat exchangers (60, 63)
do not subcool the refrigerant.
[0108] <<Fourth Connection Pipe>>
[0109] Further, a fourth connection pipe (94) is connected to a
halfway point of the second branch pipe (86) (specifically, a point
on the refrigerant suction side of the second on-off valve (36),
i.e. a point between the end of the second branch pipe (86)
connected to the high-pressure liquid pipe (81) and the second
on-off valve (36)). The fourth connection pipe (94), of which one
end is connected to the halfway point of the second branch pipe
(86), has the other end connected to a halfway point of the
low-pressure liquid pipe (82).
[0110] <<Fifth Connection Pipe>>
[0111] A fifth connection pipe (95) is connected to a halfway point
of the fourth connection pipe (94). The fifth connection pipe (95),
of which one end is connected to the halfway point of the fourth
connection pipe (94), has the other end connected to a halfway
point of the low-pressure gas pipe (83) (specifically, a point
between the suction side of the compressor (21) and the suction
proportional valve (66)). The fifth connection pipe (95) is
provided with a third on-off valve (37).
[0112] <<Third on-Off Valve>>
[0113] The third on-off valve (37) is configured to regulate the
flow rate of the refrigerant which flows through the fifth
connection pipe (95). The opening degree of the third on-off valve
(37) is adjustable in response to a control by the controller
(100). The third on-off valve (37) is provided to protect the
refrigerant circuit (16). Specifically, when a discharge pressure
of the compressor (21) (i.e., the pressure of the high-pressure
gaseous refrigerant being discharged from the compressor (21))
exceeds a predetermined abnormal high-pressure threshold, the third
on-off valve (37) is switched into an open state.
[0114] <<Sixth Connection Pipe>>
[0115] A sixth connection pipe (96) is connected to a halfway point
of the low-pressure gas pipe (83) (specifically, a point upstream
of the suction proportional valve (66) with respect to the
refrigerant flow, i.e., a point between the evaporator (25) and the
suction proportional valve (66)). The sixth connection pipe (96),
of which one end is connected to the halfway point of the
low-pressure gas pipe (83), has the other end connected to a
halfway point of the high-pressure gas pipe (80). The sixth
connection pipe (96) is provided with a fourth on-off valve
(38).
[0116] <<Fourth On-Off Valve>>
[0117] The fourth on-off valve (38) is configured to regulate the
flow rate of the refrigerant flowing through the sixth connection
pipe (96). The opening degree of the fourth on-off valve (38) is
adjustable in response to a control by the controller (100). The
fourth on-off valve (38) is provided to protect the refrigerant
circuit (16). Specifically, when the suction pressure of the
compressor (21) (i.e., the pressure of the low-pressure gaseous
refrigerant being sucked into the compressor (21)) becomes lower
than a predetermined abnormal low-pressure threshold, the fourth
on-off valve (37) is switched into an open state.
[0118] <<Various Kinds of Sensors>>
[0119] The refrigerant circuit (16) is provided with various kinds
of sensors. In this example, the refrigerant circuit (16) is
provided with a high pressure switch (110), a high pressure sensor
(111), a discharge temperature sensor (112), a low pressure sensor
(113), and a suction temperature sensor (114). The high pressure
switch (110), the high pressure sensor (111), and the discharge
temperature sensor (112) are arranged on the high-pressure gas pipe
(80) of the refrigerant circuit (16). The low pressure sensor (113)
and the suction temperature sensor (114) are arranged between the
evaporator (25) and the compressor (21) on the low-pressure gas
pipe (83).
[0120] The high pressure sensor (111) is configured to detect the
pressure of the high-pressure gaseous refrigerant being discharged
from the compressor (21) (i.e., the discharge pressure of the
compressor (21)). The discharge temperature sensor (112) is
configured to detect the temperature of the high-pressure gaseous
refrigerant being discharged from the compressor (21). The low
pressure sensor (113) is configured to detect the pressure of the
low-pressure gaseous refrigerant being sucked into the compressor
(21) (i.e., the suction pressure of the compressor (21)). The
suction temperature sensor (114) is configured to detect the
temperature of the low-pressure gaseous refrigerant being sucked
into the compressor (21). The values (pressures and temperatures)
detected by these sensors (111-114) are transmitted to the
controller (100), and used appropriately for various kinds of
controls to be detailed later.
[0121] <Configuration of Controller>
[0122] The controller (100) is configured to control the operation
of the container refrigeration device (10). Specifically, the
controller (100) controls the cooling section (18) such that the
cooling operation or the dehumidifying operation is performed. As
shown in FIG. 5, during the dehumidifying operation, a first,
second or third dehumidifying control is performed in this example.
The controller (100) includes a temperature control section (101),
a target control section (201), and an operation control section
(105).
[0123] <<Temperature Control Section>>
[0124] The temperature control section (101) monitors, during the
cooling and dehumidifying operations, the temperature of the blown
air detected by the blown air temperature sensor (34) (i.e., the
detected blown air temperature (Tss)), and controls the cooling
section (18) such that the detected blown air temperature (Tss)
becomes equal to a target temperature (Tx). Specifically, the
temperature control section (101) performs first cooling if the
detected blown air temperature (Tss) is higher than the target
temperature (Tx). The temperature control section (101) performs
second cooling if the detected blown air temperature (Tss) is lower
than the target temperature (Tx). The first cooling is performed to
increase the cooling capacity of the evaporator (25). The second
cooling is performed to reduce the cooling capacity of the
evaporator (25).
[0125] In this example, when performing the first cooling, the
temperature control section (101) increases the opening degree of
the suction proportional valve (66) of the refrigerant circuit
(16). When performing the second cooling, the temperature control
section (101) reduces the opening degree of the suction
proportional valve (66) of the refrigerant circuit (16). When the
modes of operation of the container refrigeration device (10) are
changed from the dehumidifying operation to the cooling operation,
the temperature control section (101) performs the first or second
cooling in accordance with the opening degree of the suction
proportional valve (66) of the refrigerant circuit (16).
Specifically, the temperature control section (101) performs the
first cooling if the opening degree of the suction proportional
valve (66) is greater than "100 pls." The temperature control
section (101) performs the second cooling if the opening degree of
the suction proportional valve (66) is "100 pls" or less.
[0126] <<Target Control Section>>
[0127] The target control section (201) is configured to set (or
correct) the target temperature with respect to the detected blown
air temperature (Tss) during the cooling and dehumidifying
operations. The target control section (201) includes a target
setting section (102), a first correction section (103), and a
second correction section (104).
[0128] --Target Setting Section--
[0129] During the cooling operation, the target setting section
(102) sets the target temperature (Tx) to be a first preset
temperature, which is equal to a preset inside temperature (Tsp)
that has been determined in advance with respect to the inside
temperature of the container (C). When the modes of operation of
the container refrigeration device (10) are changed from the
cooling operation to the dehumidifying operation, the target
setting section (102) sets the target temperature (Tx) to be a
second preset temperature, which is the sum of the preset inside
temperature (Tsp) and a predetermined target increment temperature.
In other words, the second preset temperature is a value which is
higher than the preset value of the inside temperature (i.e., the
preset inside temperature (Tsp)) of the container (C) by a
predetermined value.
[0130] In this example, the target setting section (102) sets the
target temperature (Tx) to be the second preset temperature when
the first or second dehumidifying control is being performed. The
target setting section (102) sets the target temperature (Tx) to be
the first preset temperature when the cooling operation or the
third dehumidifying control is being performed. For example, as
shown in FIG. 6, the target increment temperature is set to
"0.6.degree. C." Note that "0.6.degree. C." is an example of the
target increment temperature, and the target increment temperature
is not limited to this value.
[0131] --First Correction Section--
[0132] The first correction section (103) monitors the temperature
of the sucked air detected by the sucked air temperature sensor
(33) (i.e., the detected sucked air temperature (Trs)). If the
detected sucked air temperature (Trs) becomes higher (or lower)
than a predetermined reference sucked air temperature after the
modes of operation of the container refrigeration device (10) have
been changed from the cooling operation to the dehumidifying
operation, the first correction section (103) corrects the target
temperature (Tx). Specifically, the first correction section (103)
lowers the target temperature (Tx) when the detected sucked air
temperature (Trs) becomes higher than the reference sucked air
temperature. The first correction section (103) raises the target
temperature (Tx) when the detected sucked air temperature (Trs)
becomes lower than the reference sucked air temperature. Further,
the first correction section (103) may be configured to
periodically perform the correction of the target temperature (Tx)
(i.e., to periodically correct the target temperature (Tx) in
accordance with the results of comparison between the detected
sucked air temperature (Trs) and the reference sucked air
temperature) after the modes of operation of the container
refrigeration device (10) have been changed from the cooling
operation to the dehumidifying operation.
[0133] The first correction section (103) corrects the target
temperature (Tx) such that the target temperature (Tx) becomes
equal to or higher than the preset inside temperature (Tsp). In
other words, the lower limit of the target temperature (Tx) is set
to be the preset inside temperature (Tsp).
[0134] In this example, the reference sucked air temperature is set
to be a temperature which is detected by the sucked air temperature
sensor (33) when the cooling operation is stably performed (i.e.,
the temperature of the sucked air detected by the sucked air
temperature sensor (33) when the cooling operation is in a
stabilized state; hereinafter referred to as the stabilized sucked
air temperature (Trs')). For example, "when the cooling operation
is stably performed (i.e. when the cooling operation is in a
stabilized state)" refers herein to a situation in which, after the
inside of the container (C) has been cooled and the temperature of
the blown air has been lowered as a result of the cooling
operation, the temperature of the blown air (specifically, the
detected blown air temperature (Tss)) is controlled and allowed to
vary within a predetermined temperature range relative to the
preset inside temperature (Tsp), as shown in FIG. 8. The first
correction section (103) of the target control section (201) may be
configured to memorize the stabilized sucked air temperature (Trs')
when the cooling operation is performed (i.e., before a switch is
made from the cooling operation to the dehumidifying
operation).
[0135] In this example, as shown in FIG. 6, the first correction
section (103) corrects the target temperature (Tx) by adding a
first correction temperature (Y) to the target temperature (Tx).
That is to say, the target temperature (Tx) corrected by the first
correction section (103) corresponds to the sum of the yet-to-be
corrected target temperature (Tx) and the first correction
temperature (Y). The first correction section (103) sets the first
correction temperature (Y) to be a negative value if the detected
sucked air temperature (Trs) is higher than the reference sucked
air temperature. The first correction section (103) sets the first
correction temperature (Y) to be a positive value if the detected
sucked air temperature (Trs) is lower than the reference sucked air
temperature.
[0136] In this example, as shown in FIGS. 7A and 7B, the first
correction section (103) is configured to periodically perform an
adjustment of the first correction temperature (i.e. adjustment of
the first correction temperature based on comparison between the
detected sucked air temperature (Trs) and the reference sucked air
temperature) after a switch has been made from the cooling
operation to the dehumidifying operation. For example, supposing
that the reference sucked air temperature is set to be the
stabilized sucked air temperature (Trs'); and that the yet-to-be
corrected target temperature (Tx) is set to be the second preset
temperature that is the sum of the preset inside temperature (Tsp)
and the target increment temperature (+0.6.degree. C.) (i.e.,
Tsp+0.6.degree. C.); and that the first correction temperature (Y)
representing a negative value is set to be "-0.2.degree. C."; and
that the first correction temperature (Y) representing a positive
value is set to be "+4.2.degree. C., the first correction section
(103) corrects the target temperature (Tx) in the flowing
manner.
[0137] As show in FIG. 7A, after a switch has been made from the
cooling operation to the dehumidifying operation, if the detected
sucked air temperature (Trs) becomes higher than the stabilized
sucked air temperature (Trs), the first correction section (103)
adds the first correction temperature representing a negative value
(-0.2.degree. C.) to the target temperature (Tx). Consequently, the
target temperature (Tx) is corrected into "Tsp+0.6.degree.
C.-0.2.degree. C." If the detected sucked air temperature (Trs)
after the switch into the dehumidifying operation is still higher
than the stabilized sucked air temperature (Trs) even after this
correction, the first correction section (103) further adds the
first correction temperature representing a negative value
(-0.2.degree. C.) to the corrected target temperature (Tx).
Consequently, the target temperature (Tx) is further corrected into
"Tsp+0.6.degree. C.-(0.2.degree. C..times.2)."
[0138] On the other hand, as shown in FIG. 7B, after a switch has
been made from the cooling operation to the dehumidifying
operation, if the detected sucked air temperature (Trs) becomes
lower than the stabilized sucked air temperature (Trs'), the first
correction section (103) adds the first correction temperature
representing a positive value (+0.2.degree. C.) to the target
temperature (Tx). Consequently, the target temperature (Tx) is
corrected into "Tsp+0.6.degree. C.+0.2.degree. C." If the detected
sucked air temperature (Trs) after the switch into the
dehumidifying operation is still lower than the stabilized sucked
air temperature (Trs') even after this correction, the first
correction section (103) further adds the first correction
temperature representing a positive value (+0.2.degree. C.) to the
corrected target temperature (Tx). Consequently, the target
temperature (Tx) is further corrected into "Tsp+0.6.degree.
C.+(0.2.degree. C..times.2)."
[0139] --Second Correction Section--
[0140] When the dehumidifying operation is being performed (in this
example, when the second dehumidifying control is being performed),
the second correction section (104) monitors the dehumidifying
capacity of the evaporator (25). The second correction section
(104) corrects the target temperature (Tx) in accordance with the
dehumidifying capacity of the evaporator (25) such that the target
temperature (Tx) rises as the dehumidifying capacity of the
evaporator (25) increases. That is to say, the second correction
section (104) raises the target temperature (Tx) as the
dehumidifying capacity of the evaporator (25) increases.
[0141] In this example, when the dehumidifying operation is being
performed (specifically, when the second dehumidifying control is
being performed), the second correction section (104) monitors the
discharge pressure of the compressor (21) (i.e., the pressure of
the refrigerant which is being discharged) detected by the high
pressure sensor (111). The second correction section (104) corrects
the target temperature (Tx) in accordance with the discharge
pressure of the compressor (21) such that the target temperature
(Tx) rises as the discharge pressure of the compressor (21)
rises.
[0142] In this example, as shown in FIG. 6, the second correction
section (104) corrects the target temperature (Tx) by adding a
second correction temperature (Z) to the target temperature (Tx).
That is to say, the target temperature (Tx) corrected by the second
correction section (104) corresponds to the sum of the yet-to-be
corrected target temperature (Tx) and the second correction
temperature (Z). Further, the second correction section (104)
adjusts the second correction temperature (Z) in accordance with
the dehumidifying capacity of the evaporator (25) (in this example,
the discharge pressure of the compressor (21)) such that the second
correction temperature (Z) rises as the dehumidifying capacity of
the evaporator (25) increases (i.e., as the discharge pressure of
the compressor (21) increases, in this example). For example, as
shown in FIG. 6, the second correction section (104) increases the
second correction temperature (Z) stepwise to "0.2.degree. C.,"
"0.4.degree. C.," and "0.6.degree. C." in this order as the
dehumidifying capacity of the evaporator (25) Increases.
[0143] <<Operation Control Section>>
[0144] Upon activation of the container refrigeration device (10),
the operation control section (105) sets the operation mode of the
container refrigeration device (10) to be the cooling operation.
The operation control section (105) monitors the detected sucked
air humidity (i.e., the humidity of the sucked air detected by the
humidity sensor (53)), the detected sucked air temperature (Trs),
and the detected blown air temperature (Tss), and changes the modes
of operation of the container refrigeration device (10) (i.e. from
the cooling operation into the dehumidifying operation, or vice
versa). The operation control section (105) further performs any
one of the first to third dehumidifying controls when the
dehumidifying operation is being performed.
[0145] --Control During Cooling Operation--
[0146] During the cooling operation, the operation control section
(105) controls the cooling section (18) such that the heating
device (17) (the reheat heat exchanger (32), in this example) is at
rest and the sucked air which has been sucked from inside of the
container (C) is cooled by the evaporator (25) of the refrigerant
circuit (16).
[0147] In this example, during the cooling operation, the operation
control section (105) holds the first on-off valve (35) and the
reheat solenoid valve (70) open and closed, respectively. The
operation control section (105) also adjusts the opening degree of
the expansion valve (76) to be a predetermined degree, and
basically keeps the compressor (21), the outer fan (24), and the
inner fans (26) running.
[0148] --First Dehumidifying Control--
[0149] When performing the first dehumidifying control, the
operation control section (105) controls the cooling section (18)
such that the sucked air which has been sucked from inside of the
container (C) is cooled and dehumidified by the evaporator (25) of
the refrigerant circuit (16), and then heated by the heating device
(17) (the reheat heat exchanger (32), in this example).
[0150] In this example, when performing the first dehumidifying
control, the operation control section (105) allows part of the
refrigerant discharged from the compressor (21) to directly enter
the reheat heat exchanger (32). Specifically, the operation control
section (105) holds the first on-off valve (35) and the reheat
solenoid valve (70) both open, adjusts the opening degree of the
expansion valve (76) to be a predetermined degree, and basically
keeps the compressor (21), the outer fan (24), and the inner fans
(26) running.
[0151] --Second Dehumidifying Control--
[0152] In this example, when performing the second dehumidifying
control, the operation control section (105) holds the first on-off
valve (35) and the reheat solenoid valve (70) both open, adjusts
the opening degree of the expansion valve (76) to be a
predetermined degree, and basically keeps the compressor (21), the
outer fan (24), and the inner fans (26) running, as in the first
dehumidifying control.
[0153] Further, when performing the second dehumidifying control,
the operation control section (105) controls the cooling section
(18) such that the evaporator (25) has a greater dehumidifying
capacity than its capacity during the first dehumidifying control.
Further, when performing the second dehumidifying control, the
operation control section (105) controls the cooling section (18)
in accordance with a dehumidification load (i.e., the difference
between the humidity of the sucked air detected by the humidity
sensor (53) and a predetermined target humidity) such that the
dehumidifying capacity of the evaporator (25) of the refrigerant
circuit (16) increases as the dehumidification load increases. That
is to say, the operation control section (105) increases the
dehumidifying capacity of the evaporator (25) as the
dehumidification load increases.
[0154] In this example, when performing the second dehumidifying
control, the operation control section (105) monitors the discharge
pressure of the compressor (21) detected by the high pressure
sensor (111), and controls the outer fan (24) such that the
discharge pressure of the compressor (21) becomes equal to a
predetermined target discharge pressure. Specifically, the
operation control section (105) turns OFF the outer fan (24) if the
discharge pressure of the compressor (21) is lower than the target
discharge pressure, and turns ON the outer fan (24) if the
discharge pressure of the compressor (21) is higher than the target
discharge pressure. Further, in this example, when performing the
second dehumidifying control, the operation control section (105)
monitors the dehumidification load, and sets the target discharge
pressure in accordance with the dehumidification load such that the
target discharge pressure rises as the dehumidification load
increases. The minimum of the target discharge pressure (which is
variable) at the time of the second dehumidifying control is higher
than the target discharge pressure (which is constant) at the time
of the first dehumidifying control.
[0155] --Third Dehumidifying Control--
[0156] When performing the third dehumidifying control, the
operation control section (105) controls the cooling section (18)
such that the heating device (17) (the reheat heat exchanger (32),
in this example) is at rest and sucked air which has been sucked
from inside of the container (C) is cooled and dehumidified by the
evaporator (25) of the refrigerant circuit (16).
[0157] In this example, when performing the third dehumidifying
control, the operation control section (105) holds the first on-off
valve (35) and the reheat solenoid valve (70) open and closed,
respectively. The operation control section (105) also adjusts the
opening degree of the expansion valve (76) to be a predetermined
degree, and basically keeps the compressor (21), the outer fan
(24), and the inner fans (26) running.
[0158] <Change of Modes of Operation>
[0159] Next, it will be described with reference to FIG. 5 how the
operation control section (105) changes the modes of operation. In
this example, the operation control section (105) makes a switch
from the cooling operation to the dehumidifying operation, or vice
versa, and from one of the first, second and third dehumidifying
controls to another in the following manner.
[0160] <<From Cooling Operation to Dehumidifying
Operation>>
[0161] If all of the following conditions are satisfied when the
cooling operation is being performed, the operation control section
(105) changes the modes of operation of the container refrigeration
device (10) from the cooling operation to the dehumidifying
operation: [0162] Condition 1: the detected sucked air humidity
(the humidity of the sucked air detected by the humidity sensor
(53)) is higher than the predetermined target humidity; [0163]
Condition 2: the detected blown air temperature (Tss) is within a
predetermined blown air temperature range (i.e., a temperature
range including the target temperature (Tx)); and [0164] Condition
3: the detected sucked air temperature (Trs) is within a
predetermined sucked air temperature range (i.e., a temperature
range including the target temperature (Tx)).
[0165] <<From First Dehumidifying Control to Second
Dehumidifying Control>>
[0166] Upon a change of the modes of operation of the container
refrigeration device from the cooling operation to the
dehumidifying operation, the operation control section (105)
performs the first dehumidifying control. When performing the first
dehumidifying control, if all of the following conditions are
satisfied, the operation control section (105) finishes the first
dehumidifying control to start performing the second dehumidifying
control: [0167] Condition 1: the detected sucked air humidity is
higher than the target humidity; and [0168] Condition 2: the
detected blown air temperature (Tss) is within the blown air
temperature range.
[0169] <<From Second Dehumidifying Control to First
Dehumidifying Control>>
[0170] When performing the second dehumidifying control, if at
least one of the following conditions is satisfied, the operation
control section (105) finishes the second dehumidifying control to
start performing the first dehumidifying control: [0171] Condition
1: the detected sucked air humidity is lower than a predetermined
reference humidity (which is lower than the target humidity); and
[0172] Condition 2: the detected blown air temperature (Tss) is
higher than a predetermined first reference temperature (which
falls within the blown air temperature range).
[0173] <<From First Dehumidifying Control to Third
Dehumidifying Control>>
[0174] When performing the first dehumidifying control, if the
following condition is satisfied, the operation control section
(105) finishes the first dehumidifying control to start performing
the third dehumidifying control: [0175] Condition 1: the detected
blown air temperature (Tss) is higher than a predetermined second
reference temperature (which is higher than the first reference
temperature and lower than the upper limit temperature of the blown
air temperature range).
[0176] <<From Third Dehumidifying Control to First
Dehumidifying Control>>
[0177] When performing the third dehumidifying control, if all of
the following conditions are satisfied, the operation control
section (105) finishes the third dehumidifying control to start
performing the first dehumidifying control: [0178] Condition 1: the
detected sucked air humidity is higher than the target humidity;
and [0179] Condition 2: the detected blown air temperature (Tss) is
within the blown air temperature range.
[0180] <<From Dehumidifying Operation to Cooling
Operation>>
[0181] When performing the dehumidifying operation (specifically,
when performing the first, second or third dehumidifying control),
if at least one of the following conditions is satisfied, the
operation control section (105) changes the modes of operation of
the container refrigeration device (10) from the dehumidifying
operation to the cooling operation: [0182] Condition 1: the
detected sucked air humidity is lower than the target humidity;
[0183] Condition 2: the detected blown air temperature (Tss) is
lower than the lower limit temperature of the blown air temperature
range; [0184] Condition 3: the detected sucked air temperature
(Trs) is lower than the lower limit temperature of the sucked air
temperature range; and [0185] Condition 4: the detected sucked air
temperature (Trs) is higher than the upper limit temperature of the
sucked air temperature range.
[0186] <Operation of Container Refrigeration Device>
[0187] Next, it will be described how the container refrigeration
device (10) of the first embodiment performs the cooling and
dehumidifying operations. For the sake of simplicity, in the
following description, the second, third and fourth on-off valves
(36, 37 and 38), and the heater solenoid valve (71) are supposed to
be in a closed state.
[0188] <<Cooling Operation>>
[0189] During the cooling operation, the first on-off valve (35) is
held open, the reheat solenoid valve (70) is held closed, and the
opening degree of the expansion valve (76) is adjusted to be a
predetermined degree. The compressor (21), the outer fan (24), and
the inner fans (26) are basically kept running.
[0190] The refrigerant discharged from the compressor (21) passes
through the high-pressure gas pipe (80) to be directed toward the
condenser (23). When flowing through the condenser (23), the
refrigerant exchanges heat with the air which is passing through
the condenser (23) (i.e., outside air which has been blown by the
outer fan (24)). Consequently, the refrigerant in the condenser
(23) dissipates heat into the air (the outside air) passing through
the condenser (23) and condenses.
[0191] The liquid refrigerant which has flowed out of the condenser
(23) passes through the high-pressure liquid pipe (81) to flow into
the receiver (73), where the refrigerant is separated into a
saturated liquid and a saturated gas. The saturated liquid
refrigerant is directed toward the first high-pressure side channel
(61) of the first subcooling heat exchanger (60).
[0192] The refrigerant which has passed through the first
high-pressure side channel (61) of the first subcooling heat
exchanger (60) flows through the high-pressure liquid pipe (81),
and then passes through the first on-off valve (35). The
refrigerant which has passed through the first on-off valve (35)
enters the dryer (42), where the moisture of the refrigerant is
captured. Thereafter, the refrigerant flows into the second
high-pressure side channel (64) of the second subcooling heat
exchanger (63). After passing through the second high-pressure side
channel (64) of the second subcooling heat exchanger (63), the
refrigerant flows through the high-pressure liquid pipe (81), and
is decompressed by the expansion valve (76). The refrigerant then
flows through the low-pressure liquid pipe (82) to be directed
toward the evaporator (25).
[0193] The refrigerant that is flowing through the evaporator (25)
exchanges heat with the air which is passing through the evaporator
(25) (i.e., the inside air which has been blown by the inner fans
(26), i.e., the sucked air). Consequently, the refrigerant that is
flowing through the evaporator (25) absorbs heat from the air (the
sucked air) that is passing through the evaporator (25) and
evaporates, thereby cooling the air (the sucked air) that is
passing through the evaporator (25). The refrigerant which has
flowed out of the evaporator (25) flows through the low-pressure
gas pipe (83) and passes through the suction proportional valve
(66). Then, the refrigerant is sucked into the compressor (21) to
be compressed there again.
[0194] In this manner, during the cooling operation, the sucked air
that has been sucked into the inner storage space (S2) from inside
of the container (C) through the air inlet (51) is cooled by the
evaporator (25), and then, passes through the reheat heat exchanger
(32) which is at rest. Thereafter, the air is blown out through the
air outlet (52) and goes back into the inside of the container
(C).
[0195] During the cooling operation, the target control section
(201) sets the target temperature (Tx) to be the first preset
temperature that is equal to the preset inside temperature (Tsp).
Accordingly, the temperature control section (101) performs the
first cooling and the second cooling such that the detected blown
air temperature (Tss) becomes equal to the first preset temperature
that is equal to the preset inside temperature (Tsp).
[0196] If the detected blown air temperature (Tss) is higher than
the first preset temperature, the temperature control section (101)
performs the first cooling, during which the temperature control
section (101) increases the opening degree of the suction
proportional valve (66) of the refrigerant circuit (16). This
increases the flow rate of the refrigerant circulating through the
refrigerant circuit (16), and increases the cooling capacity of the
evaporator (25). Consequently, the temperature of the air that is
blown Into the container (C) after having passed sequentially
through the evaporator (25) and the reheat heat exchanger (32)
falls, and the detected blown air temperature (Tss) is lowered
toward the first preset temperature (i.e., the preset inside
temperature (Tsp)).
[0197] On the other hand, if the detected blown air temperature
(Tss) is lower than the first preset temperature, the temperature
control section (101) performs the second cooling, during which the
temperature control section (101) reduces the opening degree of the
suction proportional valve (66). This reduces the flow rate of the
refrigerant circulating through the refrigerant circuit (16), and
also reduces the cooling capacity of the evaporator (25).
Consequently, the temperature of the air that is blown into the
container (C) after having passed sequentially through the
evaporator (25) and the reheat heat exchanger (32) rises, and the
detected blown air temperature (Tss) also rises toward the first
preset temperature (i.e., the preset inside temperature (Tsp)).
During the second cooling, the temperature control section (101)
may hold the fourth on-off valve (38) open in order to protect the
compressor (21).
[0198] --Subcooling of Refrigerant in First and Second Subcooling
Heat Exchangers--
[0199] If the second on-off valve (36) is held open during the
cooling operation, the first and second subcooling heat exchangers
(60, 63) subcool the refrigerant. Specifically, the refrigerant
circulates through the refrigerant circuit (16) in the following
manner:
[0200] The refrigerant passes through the first high-pressure side
channel (61) of the first subcooling heat exchanger (60). Part of
the refrigerant is then diverted into the second branch pipe (86)
and passes through the second on-off valve (36). On the other hand,
the rest of the refrigerant flows through the high-pressure liquid
pipe (81) and passes through the first on-off valve (35). The
refrigerant that has passed through the second on-off valve (36) is
decompressed by the capillary tube (39). Thereafter, the
refrigerant passes sequentially through the second low-pressure
side channel (65) of the second subcooling heat exchanger (63) and
the first low-pressure side channel (62) of the first subcooling
heat exchanger (60), and enters the intermediate port of the
compressor (21). In the first subcooling heat exchanger (60), the
refrigerant that is flowing through the first high-pressure side
channel (61) exchanges heat with the refrigerant that is flowing
through the first low-pressure side channel (62), thereby
subcooling the refrigerant that is flowing through the first
high-pressure side channel (61).
[0201] On the other hand, the refrigerant that has passed through
the first on-off valve (35) enters the dryer (42), where moisture
is captured from the refrigerant. Thereafter, the refrigerant flows
into the second high-pressure side channel (64) of the second
subcooling heat exchanger (63). In the second subcooling heat
exchanger (63), the refrigerant that is flowing through the second
high-pressure side channel (64) exchanges heat with the refrigerant
that is flowing through the second low-pressure side channel (65),
thereby subcooling the refrigerant that is flowing through the
second high-pressure side channel (64). The refrigerant that has
been subcooled in the second high-pressure side channel (64) of the
second subcooling heat exchanger (63) flows through the
high-pressure liquid pipe (81) and enters the expansion valve (76)
where the refrigerant is decompressed. Thereafter, the refrigerant
flows through the low-pressure liquid pipe (82) to be directed
toward the evaporator (25).
[0202] Thus, if the second on-off valve (36) is held open during
the cooling operation, the first subcooling heat exchanger (60)
allows the refrigerant that is flowing through the first
high-pressure side channel (61) to exchange heat with the
refrigerant that is flowing through the first low-pressure side
channel (62), thereby subcooling the refrigerant that is flowing
through the first high-pressure side channel (61). The second
subcooling heat exchanger (63) also allows the refrigerant that is
flowing through the second high-pressure side channel (64) to
exchange heat with the refrigerant that is flowing through the
second low-pressure side channel (65), thereby subcooling the
refrigerant that is flowing through the second high-pressure side
channel (64).
[0203] <<Dehumidifying Operation (First Dehumidifying
Control)>>
[0204] When the modes of operation of the container refrigeration
device (10) are changed from the cooling operation to the
dehumidifying operation, the first dehumidifying control is
performed, and the reheat solenoid valve (70) is switched into an
open state. During the first dehumidifying control, the first
on-off valve (35) is held open, the opening degree of the expansion
valve (76) is adjusted to be a predetermined degree, and the
compressor (21), the outer fan (24), and the inner fans (26) are
basically kept running.
[0205] During the dehumidifying operation, part of the refrigerant
discharged from the compressor (21) flows through the second
connection pipe (92), passes through the reheat solenoid valve
(70), and directly enters the reheat heat exchanger (32). On the
other hand, the rest of the refrigerant discharged from the
compressor (21) (in other words, the refrigerant which does not
flows into the second connection pipe (92)) condenses in the
condenser (23), expands in the expansion valve (76), and then
evaporates in the evaporator (25), as in the cooling operation.
Specifically, the refrigerant that is flowing through the
evaporator (25) exchanges heat with the air that is passing through
the evaporator (25) (i.e., the inside air which has been blown by
the inner fans (26), i.e., the sucked air). Consequently, the
refrigerant flowing through the evaporator (25) absorbs heat from
the air (the sucked air) passing through the evaporator (25) and
evaporates. As a result, the air (the sucked air) that is passing
through the evaporator (25) is cooled to cause condensation. Thus,
the sucked air is dehumidified.
[0206] On the other hand, the refrigerant (high-pressure gaseous
refrigerant) that is flowing through the reheat heat exchanger (32)
exchanges heat with the air that is passing through the reheat heat
exchanger (32) (i.e., the air cooled and dehumidified by the
evaporator (25)). Consequently, the (high-pressure gaseous)
refrigerant that is flowing through the reheat heat exchanger (32)
condenses by dissipating heat into the air that is passing through
the reheat heat exchanger (32), and the air that is passing through
reheat heat exchanger (32) is heated.
[0207] In this manner, during the dehumidifying operation, the
sucked air that has been sucked into the inner storage space (S2)
from inside of the container (C) through the air inlet (51) is
cooled and dehumidified by the evaporator (25), and then heated by
the reheat heat exchanger (32). Thereafter, the air is blown out
through the air outlet (52) and goes back into the inside of the
container.
[0208] When the modes of operation of the container refrigeration
device (10) are changed from the cooling operation to the
dehumidifying operation (i.e., when the first dehumidifying control
is performed), the target setting section (102) sets the target
temperature (Tx) to be the second preset temperature that is the
sum of the preset inside temperature (Tsp) and the target increment
temperature. Accordingly, the temperature control section (101)
performs the first cooling and the second cooling such that the
detected blown air temperature (Tss) becomes equal to the second
preset temperature that is the sum of the preset inside temperature
(Tsp) and the target increment temperature.
[0209] If the detected blown air temperature (Tss) is higher than
the second preset temperature, the temperature control section
(101) performs the first cooling. As a result, the cooling capacity
of the evaporator (25) increases, and consequently, the temperature
of the air that is blown into the container (C) after having passed
sequentially through the evaporator (25) and the reheat heat
exchanger (32) falls, and the detected blown air temperature (Tss)
is lowered toward the second preset temperature (i.e., the sum of
the preset inside temperature (Tsp) and the target increment
temperature).
[0210] On the other hand, if the detected blown air temperature
(Tss) is lower than the second preset temperature, the temperature
control section (101) performs the second cooling. As a result, the
cooling capacity of the evaporator (25) decreases, and
consequently, the temperature of the air that is blown into the
container (C) after having passed sequentially through the
evaporator (25) and the reheat heat exchanger (32) rises, and the
detected blown air temperature (Tss) also rises toward the second
preset temperature (i.e., the sum of the preset inside temperature
(Tsp) and the target increment temperature).
[0211] With the temperature control performed in this manner, even
if the temperature of the blown air is raised by being heated by
the reheat heat exchanger (32) to make the detected blown air
temperature (Tss) higher than the target temperature (Tx), the
first cooling performed by the temperature control section (101)
can increase the cooling capacity of the evaporator (25) and lower
the temperature of the blown air. Thus, an increase in the
temperature of the blown air can be reduced during the
dehumidifying operation.
[0212] <<Second Dehumidifying Control>>
[0213] If the air inside of the container (C) still needs to be
dehumidified even after having been dehumidified through the first
dehumidifying control (that is to say, if the detected sucked air
humidity is higher than the target humidity during the first
dehumidifying control), the operation control section (105)
finishes the first dehumidifying control to start performing the
second dehumidifying control. During the second dehumidifying
control, the first on-off valve (35) and the reheat solenoid valve
(70) are held open, the opening degree of the expansion valve (76)
is adjusted to be a predetermined degree, and the compressor (21),
the outer fan (24), and the inner fans (26) are basically kept
running.
[0214] Further, during the second dehumidifying control, the target
temperature (Tx) is set to be the second preset temperature (the
sum of the preset inside temperature (Tsp) and the target increment
temperature). Accordingly, the temperature control section (101)
performs the first cooling and the second cooling such that the
detected blown air temperature (Tss) becomes equal to the second
preset temperature.
[0215] Moreover, during the second dehumidifying control, the
operation control section (105) sets the target discharge pressure
in accordance with the dehumidification load such that the target
discharge pressure rises as the dehumidification load increases.
Also, the operation control section (105) controls start/stop of
the outer fan (24) in accordance with the discharge pressure of the
compressor (21) detected by the high pressure sensor (111).
Specifically, if the discharge pressure of the compressor (21)
detected by the high pressure sensor (111) becomes lower than the
target discharge pressure, the operation control section (105)
turns OFF the outer fan (24). This interferes with the heat
exchange by the condenser (23) and raises the discharge pressure of
the compressor (21). On the other hand, if the discharge pressure
of the compressor (21) detected by the high pressure sensor (111)
becomes higher than the target discharge pressure, the operation
control section (105) turns ON the outer fan (24). This promotes
the heat exchange by the condenser (23), and reduces the discharge
pressure of the compressor (21). That is to say, the discharge
pressure of the compressor (21) rises as the target discharge
pressure rises.
[0216] The higher the discharge pressure of the compressor (21),
the higher the pressure of the refrigerant that is flowing into the
reheat heat exchanger (32), and consequently, the higher the
heating capacity of the reheat heat exchanger (32). When the
increase in the heating capacity of the reheat heat exchanger (32)
raises the temperature of the blown air to make the detected blown
air temperature (Tss) higher than the target temperature (Tx), the
temperature control section (101) performs the first cooling to
lower the detected blown air temperature (Tss). This increases the
cooling capacity of the evaporator (25) and lowers the temperature
of the blown air, thus lowering the detected blown air temperature
(Tss) toward the target temperature (Tx). Further, the increase in
the cooling capacity of the evaporator (25) leads to an increase in
the amount of water which condenses in the evaporator (25), that is
to say, leads to an increase in the dehumidifying capacity of the
evaporator (25).
[0217] As can be seen, the target discharge pressure is set in
accordance with the dehumidification load, which enables setting
the dehumidifying capacity of the evaporator (25) in accordance
with the dehumidification load such that the dehumidifying capacity
of the evaporator (25) increases as the dehumidifying load
increases.
[0218] Further, during the second dehumidifying control, to make
the detected blown air temperature (Tss) as high as the target
temperature (Tx), the temperature control section (101) and the
operation control section (105) can control the cooling section
(18) such that the cooling capacity of the evaporator (25)
increases as the heating capacity of the reheat heat exchanger (32)
increases, thereby increasing the dehumidifying capacity of the
evaporator (25).
[0219] <<Third Dehumidifying Control>>
[0220] If the detected blown air temperature (Tss) rises when the
first dehumidifying control is being performed, the operation
control section (105) finishes the first dehumidifying control to
start performing the third dehumidifying control. During the third
dehumidifying control, the reheat solenoid valve (70) is held
closed, whereas the first on-off valve (35) is held open, the
opening degree of the expansion valve (76) is adjusted to be a
predetermined degree, and the compressor (21), the outer fan (24),
and the inner fans (26) are basically kept running.
[0221] During the third dehumidifying control, the refrigerant
discharged from the compressor condenses in the condenser (23),
expands in the expansion valve (76), and then evaporates in the
evaporator (25), as in the cooling operation. Specifically, the air
(sucked air) that is passing through the evaporator (25) exchanges
heat with the refrigerant that is flowing through the evaporator
(25), and is cooled to cause condensation. In this manner, the
sucked air that has been sucked from inside of the container (C) is
cooled and dehumidified by the evaporator (25).
[0222] Further, during the third dehumidifying control, the target
setting section (102) sets the target temperature (Tx) to be the
first preset temperature that is equal to the preset inside
temperature (Tsp). Accordingly, the temperature control section
(101) performs the first cooling and the second cooling such that
the detected blown air temperature (Tss) becomes equal to the first
preset temperature.
[0223] <Variation in Temperature of Blown Air Involved with Mode
Change from Cooling Operation to Dehumidifying Operation>
[0224] During the dehumidifying operation, the air that is passing
through the heating device (17) (the reheat heat exchanger (32), in
this example) may not be uniformly heated. For example, a
temperature difference of the refrigerant present in the heat
transfer tubes of the reheat heat exchanger (32) (the heat transfer
tubes running in the width direction inside of the container)
causes the air that is blown out of the reheat heat exchanger (32)
to have non-uniformity in temperature. In such a case, once a
switch is made from the cooling operation to the dehumidifying
operation, it will be difficult for the blown air temperature
sensor (34) to detect accurately the lowest temperature of the
blown air with respect to the width direction inside of the
container. For example, if the blown air temperature sensor (34) is
provided at the middle of the width inside of the container (C) and
if the blown air does not have the lowest temperature at the middle
of the width inside the container but does have the lowest
temperature at a point which is slightly closer to an end in the
width direction than its middle point is, the temperature of the
blown air detected by the blown air temperature sensor (34) (i.e.,
the detected blown air temperature (Tss)) becomes higher than the
actual lowest temperature of the blown air with respect to the
width direction inside of the container as shown in FIG. 9.
[0225] On the other hand, in the container refrigeration device
(10) of the first embodiment, when a switch is made from the
cooling operation to the dehumidifying operation, the target
temperature (Tx) is set to be the second preset temperature (i.e.,
the sum of the preset inside temperature (Tsp) and the target
increment temperature) that is higher than the preset inside
temperature (Tsp). Therefore, the temperature of the blown air that
is blown into the container (C) can be raised on average. In this
manner, even if the air that is passing through the heating device
(17) is heated non-uniformly with respect to the width direction
inside of the container (C), the lowest temperature of the blown
air with respect to the width direction inside of the container (C)
is not allowed to be lower than the preset inside temperature
(Tsp).
[0226] <Correction of Target Temperature by First Correction
Section>
[0227] Next, it will be described how the first correction section
(103) corrects the target temperature (Tx). As described above, the
first correction section (103) monitors the temperature of sucked
air detected by the sucked air temperature sensor (33) (i.e., the
detected sucked air temperature (Trs)). After the modes of
operation of the container refrigeration device (10) are changed
from the cooling operation to the dehumidifying operation, the
first correction section (103) lowers the target temperature (Tx)
if the detected sucked air temperature (Trs) becomes higher than
the reference sucked air temperature, and raises the target
temperature (Tx) if the detected sucked air temperature (Trs)
becomes lower than the reference sucked air temperature.
[0228] The air that has been blown into the container (C) from the
evaporator (25) and the heating device (17) circulates inside of
the container (C), and then, is sucked into the evaporator (25)
again. Therefore, the air that is being sucked from inside of the
container (C) does not have as non-uniform a temperature
distribution with respect to the width direction inside of the
container (C) as the air that is being blown into the container
(C). Further, a variation in the detected sucked air temperature
(Trs) depends on a variation in the inside temperature of the
container (C). Specifically, an increase in the inside temperature
of the container (C) causes an increase in the temperature of the
sucked air and an increase in the detected sucked air temperature
(Trs). On the other hand, a decrease in the inside temperature of
the container (C) causes a decrease in the temperature of the
sucked air and a decrease in the detected sucked air temperature
(Trs). Thus, if the detected sucked air temperature (Trs) becomes
higher than the reference sucked air temperature (i.e., the
stabilized sucked air temperature (Trs'), in this example) after a
switch has been made from the cooling operation to the
dehumidifying operation, a determination can be made that the
inside temperature of the container (C) has risen. On the other
hand, if the detected sucked air temperature (Trs) becomes lower
than the reference sucked air temperature, a determination can also
be made that the inside temperature of the container (C) has
fallen.
[0229] As described above, in the container refrigeration device
(10) of the first embodiment, the first correction section (103)
corrects the target temperature (Tx) in accordance with a variation
in the detected sucked air temperature (Trs) involved with the
switch from the cooling operation to the dehumidifying operation.
Specifically, if the inside temperature of the container (C) rises
to make the detected sucked air temperature (Trs) higher than the
reference sucked air temperature (i.e., the stabilized sucked air
temperature (Trs'), in this example) after the switch from the
cooling operation to the dehumidifying operation, the first
correction section (103) lowers the target temperature (Tx). This
allows for lowering the temperature of the blown air and
eventually, the inside temperature of the container (C). On the
other hand, if the inside temperature of the container (C) falls to
make the detected sucked air temperature (Trs) lower than the
reference sucked air temperature after the switch from the cooling
operation to the dehumidifying operation, the first correction
section (103) raises the target temperature (Tx). This allows for
raising the temperature of the blown air and eventually, the inside
temperature of the container (C).
[0230] Thus, the variation in the inside temperature of the
container (C) involved with the switch from cooling operation to
the dehumidifying operation can be reduced by controlling the
temperature of the blown air in accordance with a variation in the
detected sucked air temperature (Trs) that is caused after the
switch.
[0231] <Correction of Target Temperature by Second Correction
Section>
[0232] Next, it will be described how the second correction section
(104) corrects the target temperature (Tx). As described above, the
second correction section (104) of this embodiment monitors the
discharge pressure of the compressor (21) detected by the high
pressure sensor (111) during the dehumidifying operation
(specifically, during the second dehumidifying control). The second
correction section (104) corrects the target temperature (Tx) in
accordance with the discharge pressure of the compressor (21) such
that the target temperature (Tx) rises as the discharge pressure of
the compressor (21) rises.
[0233] The dehumidifying capacity of the evaporator (25) depends on
the discharge pressure of the compressor (21). Specifically, an
increase in the discharge pressure of the compressor (21) leads to
an increase in the pressure of the refrigerant that flows into the
reheat heat exchanger (32), and consequently, to an increase in the
heating capacity of the reheat heat exchanger (32). The increase in
the heating capacity of the reheat heat exchanger (32) in turn
raises the temperature of the blown air, and accordingly, the
detected blown air temperature (Tss) becomes higher than the target
temperature (Tx). Therefore, the temperature control section (101)
controls the cooling section (18) to lower the detected blown air
temperature (Tss), and thereby increases the cooling capacity of
the evaporator (25). In this manner, the dehumidifying capacity of
the evaporator (25) increases.
[0234] Thus, since the dehumidifying capacity of the evaporator
(25) depends on the discharge pressure of the compressor (21),
correction of the target temperature (Tx) in accordance with the
discharge pressure of the compressor (21) allows for correcting the
target temperature (Tx) such that the target temperature (Tx) rises
as the dehumidifying capacity of the evaporator (25) increases.
[0235] During the dehumidifying operation, the air is dehumidified
by cooling the air and causing condensation in the evaporator (25).
Thus, during the dehumidifying operation, the temperature of the
blown air tends to fall more easily as the dehumidifying capacity
(the cooling capacity) of the evaporator (25) increases.
[0236] As described above, in the container refrigeration device
(10) of the first embodiment, during the dehumidifying operation,
the second correction section (104) corrects the target temperature
(Tx) in accordance with the dehumidifying capacity of the
evaporator (25) such that the target temperature (Tx) rises as the
dehumidifying capacity of the evaporator (25) increases. In this
manner, the temperature of the blown air can be raised if the
temperature of the blown air has a tendency to fall when the
dehumidifying operation is being performed.
Advantages of First Embodiment
[0237] As can be seen from the foregoing description, in the
container refrigeration device (10) of the first embodiment, if a
switch has been made from the cooling operation to the
dehumidifying operation, the target temperature (Tx) is set to be
the second preset temperature (i.e., the sum of the preset inside
temperature (Tsp) and the target increment temperature) that is
higher than the preset inside temperature (Tsp). Therefore, even if
the air that has passed through the heating device (17) (e.g., the
reheat heat exchanger (32), in this example) is not uniformly
heated with respect to the width direction inside of the container
(C), the lowest temperature of the blown air with respect to the
width direction inside of the container (C) is not allowed to be
lower than the preset inside temperature (Tsp). This prevents
causing chilling injury to the load inside the container (C).
[0238] In addition, a variation in the inside temperature of the
container (C), involved with the switch from the cooling operation
to the dehumidifying operation, can be reduced by correcting the
target temperature (Tx) in accordance with a variation in the
detected sucked air temperature (Trs) (specifically, a variation in
the result of comparison between the detected sucked air
temperature (Trs) and the stabilized sucked air temperature (Trs'))
after the switch has been made from the cooling operation to the
dehumidifying operation. Thus, during the dehumidifying operation,
chilling injury to a load inside the container (C) and an increase
in the inside temperature of the container (C) can be
prevented.
[0239] Further, the reference sucked air temperature, on which a
variation in the detected sucked air temperature (Trs) is
determined, is set to be the stabilized sucked air temperature
(Trs'). With the use of the stabilized sucked air temperature (Trs)
as the reference value, a determination can be made whether or not
the detected sucked air temperature (Trs) has varied along with the
inside temperature of the container (C) after the switch from the
cooling operation to the dehumidifying operation.
[0240] During the dehumidifying operation (specifically, during the
second dehumidifying control), the target temperature (Tx) is
corrected in accordance with the dehumidifying capacity of the
evaporator (25). In this manner, if the temperature of the blown
air tends to fall easily during the dehumidifying operation, the
temperature of the blown air can be raised. Thus, the temperature
inside of the container (C) can be prevented from falling, even if
the dehumidifying capacity of the evaporator (25) increases.
[0241] Since the lower limit of the target temperature (Tx) is set
to be the preset inside temperature (Tsp), an excessive decrease in
the temperature of the blown air can be prevented. This prevents an
excessive decrease in the inside temperature of the container (C).
Thus, chilling injury to a load inside the container (C) can
prevented reliably during the dehumidifying operation.
[0242] Moreover, in the container refrigeration device (10) of the
first embodiment, during the dehumidifying operation (specifically,
during the first dehumidifying control), the sucked air which has
been sucked from inside of the container (C) can be cooled and
dehumidified by the evaporator (25) and heated by the reheat heat
exchanger (32). Thus, prevention of a decrease in the inside
temperature of the container (C) and dehumidification of the air
inside of the container (C) can be achieved.
[0243] In addition, in the container refrigeration device of the
first embodiment, during the dehumidifying operation (specifically,
during the second dehumidifying control), the cooling capacity of
the evaporator (25) can be increased along with an increase in the
heating capacity of the reheat heat exchanger (32) such that the
detected blown air temperature (Tss) becomes equal to the target
temperature (Tx), thereby increasing the dehumidifying capacity of
the evaporator (25). Thus, reduction of a variation in the inside
temperature of the container (C) and increase in the dehumidifying
capacity of the evaporator (25) can be achieved.
[0244] <Variation of Operation Control Section>
[0245] Optionally, the operation control section (105) may be
configured to monitor a superheat degree of the evaporator (25) and
to control the opening degree of the expansion valve (76) of the
cooling section (18) such that the superheat degree of the
evaporator (25) becomes equal to a predetermined target superheat
degree. Specifically, if the superheat degree of the evaporator
(25) is lower than the target superheat degree, the operation
control section (105) may reduce the opening degree of the
expansion valve (76) to increase the superheat degree of the
evaporator (25). If the superheat degree of the evaporator (25) is
higher than the target superheat degree, the operation control
section (105) may increase the opening degree of the expansion
valve (76) to reduce the superheat degree of the evaporator
(25).
[0246] Further, when performing the second dehumidifying control,
if the discharge pressure of the compressor (21) is equal to the
maximum (the limit value), the operation control section (105) may
increase the dehumidifying capacity of the evaporator (25) in the
following manner. Specifically, when performing the second
dehumidifying control, the operation control section (105) may
monitor the dehumidification load, and set the target superheat
degree in accordance with the dehumidification load such that the
target superheat degree increases as the dehumidification load
increases. For example, the operation control section (105) may
increase the target superheat degree stepwise to "2.degree. C.,"
"5.degree. C.," "8.degree. C." "11.degree. C.," and "14.degree. C."
in this order as the dehumidification load increases.
[0247] An increase in the superheat degree of the evaporator (25)
leads to a decrease in the suction pressure of the compressor (21)
and a decrease in an outlet evaporation temperature of the
evaporator (25). This results in an increase in the amount of water
that condenses in the evaporator (25). A decrease in the suction
pressure of the compressor (21) leads to an increase in the
specific volume of the refrigerant that flows through the
evaporator (25) and a decrease in the flow rate of the refrigerant
that circulates through the refrigerant circuit (16). Consequently,
the cooling capacity of the evaporator (25) decreases, and the
temperature of the blown air rises. When the temperature of the
blown air rises to make the detected blown air temperature (Tss)
higher than the target temperature (Tx), the temperature control
section (101) performs the first cooling (specifically, increases
the opening degree of the suction proportional valve (66) to
increase the flow rate of refrigerant that circulates through the
refrigerant circuit (16)). In this manner, the cooling capacity of
the evaporator (25) increases and the temperature of the blown air
falls. As a result, the detected blown air temperature (Tss) falls
toward the target temperature (Tx).
[0248] Thus, by setting the target superheat degree in accordance
with the dehumidification load, the dehumidifying capacity of the
evaporator (25) can be set in accordance with the dehumidification
load such that the dehumidifying capacity of the evaporator (25)
increases as the dehumidification load increases.
[0249] By making the temperature control section (101) and the
operation control section (105) control the cooling section (18),
the flow rate of the refrigerant that circulates through the
refrigerant circuit (16) can be increased as the outlet evaporation
temperature of the evaporator (25) falls such that the detected
blown air temperature (Tss) becomes equal to the target temperature
(Tx). Thus, reduction of a variation in the inside temperature of
the container (C) and increase in the dehumidifying capacity of the
evaporator (25) can be achieved.
Second Embodiment
[0250] Next, a container refrigeration device (10) according to a
second embodiment will be described. In the container refrigeration
device (10) of the second embodiment, a reference sucked air
temperature is not set to be a stabilized sucked air temperature
(Trs), but a preset sucked air temperature which is the sum of a
preset inside temperature (Tsp) and a predetermined sucked air
increment temperature. (In other words, the preset sucked air
temperature is a value which is based on the preset value (the
preset inside temperature (Tsp)) of the inside temperature of the
container (C)). Specifically, after a switch has been made from a
cooling operation to a dehumidifying operation, a first correction
section (103) lowers a target temperature (Tx) if a detected sucked
air temperature (Trs) becomes higher than the preset sucked air
temperature. The first correction section (103) raises the target
temperature (Tx) if the detected sucked air temperature (Trs)
becomes lower than the preset sucked air temperature. In the other
respects, the container refrigeration device (10) of the second
embodiment operates as in the container refrigeration device (10)
of the first embodiment.
[0251] Two different reference sucked air temperatures (hereinafter
referred to as "first and second reference sucked air
temperatures," respectively) may be set. Specifically, a first
reference sucked air temperature may be set to sense an increase in
the detected sucked air temperature (Trs), and a second reference
sucked air temperature may be set to sense a decrease in the
detected sucked air temperature (Trs). For example, the first
reference sucked air temperature may be set to be a first preset
sucked air temperature which is the sum of the preset inside
temperature (Tsp) and a first sucked air increment temperature (of,
for example, +3.0.degree. C.). The second reference sucked air
temperature may be set to be a second preset sucked air temperature
which is the sum of the preset inside temperature (Tsp) and a
second sucked air increment temperature (which is smaller than the
first sucked air increment temperature and may be, for example,
+0.5.degree. C.).
[0252] For example, supposing that the first reference sucked air
temperature is set to be the first preset sucked air temperature
that is the sum of the preset inside temperature (Tsp) and the
first sucked air increment temperature (of +3.0.degree. C.) (i.e.,
"Tsp+3.0.degree. C."); and that the second reference sucked air
temperature is set to be the second preset sucked air temperature
that is the sum of the preset inside temperature (Tsp) and the
second sucked air increment temperature (of +0.5.degree. C.) (i.e.,
"Tsp+0.5.degree. C."); and that the yet-to-be-corrected target
temperature (Tx) is set to be a second preset temperature that is
the sum of the preset inside temperature (Tsp) and a target
increment temperature (of +0.6.degree. C.) (i.e., Tsp+0.6.degree.
C.); and that a first correction temperature (Y) representing a
negative value is set to be "-0.2.degree. C."; and that the first
correction temperature (Y) representing a positive value is set to
be "+0.2.degree. C.," the first correction section (103) corrects
the target temperature (Tx) in the following manner.
[0253] After the switch has been made from the cooling operation to
the dehumidifying operation, if the detected sucked air temperature
(Trs) becomes higher than the first reference sucked air
temperature (of Tsp+3.0.degree. C.), the first correction section
(103) adds a first correction temperature representing a negative
value (of -0.2.degree. C.) to the target temperature (Tx).
Consequently, the target temperature (Tx) is corrected into
"Tsp+0.6.degree. C.-0.2.degree. C." If the detected sucked air
temperature (Trs) after the switch into the dehumidifying operation
is still higher than the first reference sucked air temperature (of
Tsp+3.0.degree. C.) even after this correction, the first
correction section (103) further adds the first correction
temperature representing a negative value (of -0.2.degree. C.) to
the corrected target temperature (Tx). Consequently, the target
temperature (Tx) is further corrected into "Tsp+0.6.degree.
C.-(0.2.degree. C..times.2)."
[0254] On the other hand, after a switch has been made from the
cooling operation to the dehumidifying operation, if the detected
sucked air temperature (Trs) becomes lower than the second
reference sucked air temperature (of Tsp-0.5.degree. C.), the first
correction section (103) adds the first correction temperature
representing a positive value (of 40.2.degree. C.) to the target
temperature (Tx). Consequently, the target temperature (Tx) is
corrected into "Tsp+0.6.degree. C.+0.2.degree. C." If the detected
sucked air temperature (Trs) after the switch into the
dehumidifying operation is still lower than the second reference
sucked air temperature (of Tsp+0.5.degree. C.) even after this
correction, the first correction section (103) further adds the
first correction temperature representing a positive value (of
+0.2.degree. C.) to the corrected target temperature (Tx).
Consequently, the target temperature (Tx) is further corrected into
"Tsp+0.6.degree. C.+(0.2.degree. C..times.2)."
Advantages of Second Embodiment
[0255] As can be seen from the foregoing description, by setting
the reference sucked air temperature used to sense a variation in
the detected sucked air temperature (Trs) to be the preset sucked
air temperature (i.e., the sum of the preset inside temperature
(Tsp) and the sucked air increment temperature), a determination
can be made, by reference to the preset sucked air temperature,
whether or the detected sucked air temperature (Trs) has varied
along with the inside temperature of the container (C) after the
switch has been made from the cooling operation to the
dehumidifying operation.
[0256] Besides this advantage, the container refrigeration device
(10) of the second embodiment has the same or similar effects and
functions as/to the container refrigeration device (10) of the
first embodiment.
Third Embodiment
[0257] Next, a container refrigeration device (10) according to a
third embodiment will be described. In the container refrigeration
device (10) of the third embodiment, the heating device (17) is not
implemented as a reheat heat exchanger (32) but as an electric
heater (78). The container refrigeration device (10) of the third
embodiment has the same configuration as the container
refrigeration device (10) of the first embodiment, except that the
following components are omitted from the refrigerant circuit (16)
in the container refrigeration device (10) of the third embodiment:
namely, the reheat heat exchanger (32) and its associated members
(specifically, the first branch pipe (85), the second connection
pipe (92), the reheat solenoid valve (70), and the reheat heat
exchanger (32)); and the drain pan heater (77) and its associated
members (specifically, the first and third connection pipes (91,
93), the heater solenoid valve (71), and the drain pan heater
(77)).
[0258] <Electric Heater>
[0259] The electric heater (78) is configured such that its heating
capacity is variable in response to a control by the controller
(100). The electric heater (78) is provided downstream of the
evaporator (25) with respect to the direction in which sucked air
which has been sucked from inside of the container (C) flows. The
electric heater (78) extends substantially parallel to the
evaporator (25) in the width direction inside of the container
(C).
[0260] <Operation Control Section>
[0261] In this example, during the cooling and dehumidifying
operations (specifically, during first to third dehumidifying
controls), the operation control section (105) controls the
electric heater (78) in the following manner. Note that the
operation control section (105) changes the modes of operation and
changes the modes of control from one of the first to third
dehumidifying controls to another as in the first embodiment.
[0262] <<Control During Cooling Operation>>
[0263] During the cooling operation, the operation control section
(105) keeps the electric heater (78) at rest. During the cooling
operation, as in the first embodiment, the operation control
section (105) holds the first on-off valve (35) open, adjusts the
opening degree of the expansion valve (76) to be a predetermined
opening degree, and basically keeps the compressor (21), the outer
fan (24), and the inner fans (26) running.
[0264] <<First Dehumidifying Control>>
[0265] When performing the first dehumidifying control, the
operation control section (105) keeps the electric heater (78) in
operation. When performing the first dehumidifying control, as in
the first embodiment, the operation control section (105) holds the
first on-off valve (35) open, adjusts the opening degree of the
expansion valve (76) to be a predetermined opening degree, and
basically keeps the compressor (21), the outer fan (24), and the
inner fans (26) running.
[0266] <<Second Dehumidifying Control>>
[0267] When performing the second dehumidifying control, as in the
first dehumidifying control, the operation control section (105)
keeps the electric heater (78) in operation, and holds the first
on-off valve (35) open. The operation control section (105) also
adjusts the opening degree of the expansion valve (76) to be a
predetermined opening degree, and basically keeps the compressor
(21), the outer fan (24), and the inner fans (26) running. Further,
when performing the second dehumidifying control, the operation
control section (105) monitors the dehumidification load and sets
the heating capacity of the electric heater (78) in accordance with
the dehumidification load such that the heating capacity of the
electric heater (78) increases as the dehumidification load
increases. The minimum of the heating capacity (a variable value)
of the electric heater (78) during the second dehumidifying control
is higher than the heating capacity (a constant value) of the
electric heater (78) during the first dehumidifying control.
[0268] <<Third Dehumidifying Control>>
[0269] When performing the third dehumidifying control, the
operation control section (105) keeps the electric heater (78) at
rest. When performing the third dehumidifying control, as in the
first embodiment, the operation control section (105) holds the
first on-off valve (35) open, adjusts the opening degree of the
expansion valve (76) to be a predetermined opening degree, and
basically keeps the compressor (21), the outer fan (24), and the
inner fans (26) running.
[0270] <<Operation of Container Refrigeration
Device>>
[0271] Next, it will be described how the container refrigeration
device (10) of the third embodiment performs the cooling and
dehumidifying operations. The first and second correction sections
(103, 104) correct the target temperature (Tx) as in the first
embodiment. For the sake of simplicity, in the following
description, the second, third, and fourth on-off valves (36, 37,
38) are supposed to be held closed.
[0272] <<Cooling Operation>>
[0273] During the cooling operation, the electric heater (78) is at
rest, the first on-off valve (35) is held open, and the opening
degree of the expansion valve (76) is adjusted to be a
predetermined opening degree. The compressor (21), the outer fan
(24), and the inner fans (26) are basically kept running.
Accordingly, during the cooling operation, the sucked air that has
been sucked into the inner storage space (S2) from inside of the
container (C) through the air inlet (51) is cooled by the
evaporator (25), and then passes through the electric heater (78)
which is at rest. Thereafter, the air is blown out through the air
outlet (52) and goes back into the inside of the container.
[0274] As in the first embodiment, during the cooling operation,
the target control section (201) sets the target temperature (Tx)
to be the first preset temperature that is equal to the preset
inside temperature (Tsp). Accordingly, the temperature control
section (101) performs the first cooling and the second cooling
such that the detected blown air temperature (Tss) becomes equal to
the first preset temperature that is equal to the preset inside
temperature (Tsp).
[0275] <<Dehumidifying Operation (First Dehumidifying
Control)>>
[0276] When the modes of operation of the container refrigeration
device (10) are changed from the cooling operation to the
dehumidifying operation, the first dehumidifying control is
performed and the electric heater (78) is activated. During the
first dehumidifying control, the first on-off valve (35) is held
open, the opening degree of the expansion valve (76) is adjusted to
be a predetermined degree, and the compressor (21), the outer fan
(24), and the inner fans (26) are basically kept running.
[0277] During the dehumidifying operation, as in the cooling
operation, the refrigerant discharged from the compressor (21)
condenses in the condenser (23), expands in the expansion valve
(76), and then evaporates in the evaporator (25). Specifically, the
refrigerant that is flowing through the evaporator (25) exchanges
heat with the air that is passing through the evaporator (25)
(i.e., the inside air which has been blown by the inner fans (26),
i.e., the sucked air). Consequently, the refrigerant flowing
through the evaporator (25) absorbs heat from the air (the sucked
air) passing through the evaporator (25) and evaporates. As a
result, the air (the sucked air) that is passing through the
evaporator (25) is cooled to cause condensation. Thus, the sucked
air is dehumidified. On the other hand, when passing through the
electric heater (78), the air (i.e., the air that has been cooled
and dehumidified by the evaporator (25)) is heated by the electric
heater (78).
[0278] In this manner, during the dehumidifying operation, the
sucked air that has been sucked into the inner storage space (S2)
from inside of the container (C) through the air inlet (51) is
cooled and dehumidified by the evaporator (25), and then heated by
the electric heater (78). Thereafter, the air is blown out through
the air outlet (52) and goes back into the inside of the
container.
[0279] When the modes of operation of the container refrigeration
device (10) are changed from the cooling operation to the
dehumidifying operation (i.e., when the first dehumidifying control
is performed), the target setting section (102) sets the target
temperature (Tx) to be the second preset temperature that is the
sum of the preset inside temperature (Tsp) and the target increment
temperature. Accordingly, the temperature control section (101)
performs the first cooling and the second cooling such that the
detected blown air temperature (Tss) becomes equal to the second
preset temperature that is the sum of the preset inside temperature
(Tsp) and the target increment temperature.
[0280] With the temperature control performed in this manner, even
if the blown air has its temperature raised by being heated by the
electric heater (78) to make the detected blown air temperature
(Tss) higher than the target temperature (Tx), the first cooling
performed by the temperature control section (101) can increase the
cooling capacity of the evaporator (25) and lower the temperature
of the blown air. Thus, an increase in the temperature of the blown
air can be reduced during the dehumidifying operation.
[0281] <<Second Dehumidifying Control>>
[0282] If the inside air of the container (C) still needs to be
dehumidified even after having been dehumidified through the first
dehumidifying control (that is to say, if the detected sucked air
humidity is higher than the target humidity during the first
dehumidifying control), the operation control section (105)
finishes the first dehumidifying control to start performing the
second dehumidifying control. During the second dehumidifying
control, the electric heater (78) is activated, the first on-off
valve (35) is held open, the opening degree of the expansion valve
(76) is adjusted to be a predetermined degree, and the compressor
(21), the outer fan (24), and the inner fans (26) are basically
kept running.
[0283] Further, during the second dehumidifying control, the target
temperature (Tx) is set to be the second preset temperature (the
sum of the preset inside temperature (Tsp) and the target increment
temperature). That is to say, the temperature control section (101)
performs the first cooling and the second cooling such that the
detected blown air temperature (Tss) becomes equal to the second
preset temperature.
[0284] Moreover, during the second dehumidifying control, the
operation control section (105) sets the heating capacity of the
electric heater (78) in accordance with the dehumidification load
such the heating capacity of the electric heater (78) increases as
the dehumidification load increases. The heating capacity of the
electric heater (78) increases as the heat capacity of the electric
heater (78) increases. If an increase in the heating capacity of
the electric heater (78) causes an increase in the temperature of
the blown air to make the detected blown air temperature (Tss)
higher than the target temperature (Tx), the temperature control
section (101) performs the first cooling to lower the detected
blown air temperature (Tss). Consequently, the cooling capacity of
the evaporator (25) increases, and the temperature of the blown air
falls. As a result, the detected blown air temperature (Tss) falls
toward the target temperature (Tx). Further, an increase in the
cooling capacity of the evaporator (25) results in an increase in
the amount of water that condenses in the evaporator (25). Thus,
the dehumidifying capacity of the evaporator (25) increases.
[0285] As can be seen, the heating capacity of the electric heater
(78) is set in accordance with the dehumidification load, which
enables setting the dehumidifying capacity of evaporator (25) in
accordance with the dehumidification load such that the
dehumidifying capacity of evaporator (25) increases as the
dehumidifying load increases.
[0286] Further, during the second dehumidifying control, to make
the detected blown air temperature (Tss) as high as the target
temperature (Tx), the temperature control section (101) and the
operation control section (105) can control the cooling section
(18) such that the cooling capacity of the evaporator (25)
increases as the heating capacity of the electric heater (78)
increases, thereby increasing the dehumidifying capacity of the
evaporator (25).
[0287] <<Third Dehumidifying Control>>
[0288] If the detected blown air temperature (Tss) rises when the
first dehumidifying control is being performed, the operation
control section (105) finishes the first dehumidifying control to
start performing the third dehumidifying control. During the third
dehumidifying control, the electric heater (78) is kept at rest,
the first on-off valve (35) is held open, the opening degree of the
expansion valve (76) is adjusted to be a predetermined degree, and
the compressor (21), the outer fan (24), and the inner fans (26)
are basically kept running.
[0289] During the third dehumidifying control, the refrigerant
discharged from the compressor condenses in the condenser (23),
expands in the expansion valve (76), and then evaporates in the
evaporator (25), as in the cooling operation. Specifically, the air
(sucked air) that is passing through the evaporator (25) exchanges
heat with the refrigerant that is flowing through the evaporator
(25), and is cooled to cause condensation. In this manner, the
sucked air that has been sucked from inside of the container (C) is
cooled and dehumidified by the evaporator (25).
[0290] Further, during the third dehumidifying control, the target
setting section (102) sets the target temperature (Tx) to be the
first preset temperature that is equal to the preset inside
temperature (Tsp). Accordingly, the temperature control section
(101) performs the first cooling and the second cooling such that
the detected blown air temperature (Tss) becomes equal to the first
preset temperature.
Advantages of Third Embodiment
[0291] As can be seen from the foregoing, in the container
refrigeration device (10) of the third embodiment, if a switch has
been made from the cooling operation to the dehumidifying
operation, the target temperature (Tx) is set to be the second
preset temperature (i.e., the sum of the preset inside temperature
(Tsp) and the target increment temperature) that is higher than the
preset inside temperature (Tsp). Therefore, even if the air that
has passed through the heating device (17) (the electric heater
(78), in this example) is not uniformly heated with respect to the
width direction inside of the container (C), the lowest temperature
of the blown air with respect to the width direction inside of the
container (C) is not allowed to be lower than the preset inside
temperature (Tsp). This prevents causing chilling injury to a load
inside the container (C).
[0292] Further, in the container refrigeration device (10) of the
third embodiment, during the dehumidifying operation (specifically,
during the first dehumidifying control), the sucked air that has
been sucked from inside of the container (C) can be cooled and
dehumidified by the evaporator (25) and heated by the electric
heater (78). Thus, prevention of a decrease in the inside
temperature of the container (C) and dehumidification of the air
inside of the container (C) can be achieved.
[0293] In addition, in the container refrigeration device of the
third embodiment, during the dehumidifying operation (specifically,
during the second dehumidifying control), the cooling capacity of
the evaporator (25) is increased as the heating capacity of the
electric heater (78) increases such that the detected blown air
temperature (Tss) becomes equal to the target temperature (Tx),
thereby increasing the dehumidifying capacity of the evaporator
(25). Thus, reduction of a variation in the inside temperature of
the container (C) and increase in the dehumidifying capacity of the
evaporator (25) can be achieved.
[0294] Besides these advantages, the container refrigeration device
(10) of the third embodiment has the same or similar effects and
functions as/to the container refrigeration device (10) of the
first embodiment.
Other Embodiments
[0295] Although the revolution speed of the compressor (21)
(specifically, the revolution speed of the compressor motor) is
supposed to be constant in the foregoing description, the
compressor (21) may be configured such that its revolution speed is
variable in response to a control by the controller (100). In that
case, the temperature control section (101) may be configured to
control the revolution speed of the compressor (21) such that the
detected blown air temperature (Tss) becomes equal to the target
temperature (Tx). Specifically, during the first cooling, the
temperature control section (101) increases the revolution speed of
the compressor (21), which allows for increasing the flow rate of
the refrigerant that circulates through the refrigerant circuit
(16) and increasing the cooling capacity of the evaporator (25). On
the other hand, during the second cooling, the temperature control
section (101) reduces the revolution speed of the compressor (21),
which allows for decreasing the flow rate of the refrigerant that
circulates through the refrigerant circuit (16) and reducing the
cooling capacity of the evaporator (25).
[0296] Note that the embodiments described above may be combined as
appropriate. The embodiments described above are merely preferred
examples in nature, and are not intended to limit the scope,
applications, and use of the present invention.
INDUSTRIAL APPLICABILITY
[0297] As can be seen from the foregoing description, the present
invention is useful as a container refrigeration device.
DESCRIPTION OF REFERENCE CHARACTERS
[0298] 16 Refrigerant Circuit [0299] 17 Heating Device [0300] 18
Cooling Section [0301] 21 Compressor [0302] 23 Condenser [0303] 25
Evaporator [0304] 32 Reheat Heat Exchanger [0305] 33 Sucked air
Temperature Sensor [0306] 34 Blown Air Temperature Sensor [0307] 53
Humidity Sensor [0308] 76 Expansion Valve (Expansion Mechanism)
[0309] 78 Electric Heater [0310] 101 Temperature Control Section
[0311] 102 Target Setting Section [0312] 103 First Correction
Section [0313] 104 Second Correction Section [0314] 105 Operation
Control Section [0315] 201 Target Control Section
* * * * *