U.S. patent application number 16/645545 was filed with the patent office on 2020-08-20 for refrigeration machine.
The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Masashi FUJITSUKA, Komei NAKAJIMA.
Application Number | 20200263916 16/645545 |
Document ID | 20200263916 / US20200263916 |
Family ID | 1000004839908 |
Filed Date | 2020-08-20 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200263916 |
Kind Code |
A1 |
NAKAJIMA; Komei ; et
al. |
August 20, 2020 |
REFRIGERATION MACHINE
Abstract
The expansion device is configured to have a degree of opening
corresponding to a fully closed state while the compressor is
non-operational. The fan is configured to become non-operational
when transition is made, while the compressor is non-operational,
from a state in which a temperature difference between a detection
temperature of the first temperature sensor and a detection
temperature of the second temperature sensor is larger than a
criterion value to a state in which the temperature difference is
smaller than the criterion value. The fan is configured to become
operational when transition is made, while the compressor is
operational, from a state in which the temperature difference is
smaller than a second criterion value to a state in which the
temperature difference is larger than the second criterion
value.
Inventors: |
NAKAJIMA; Komei; (Tokyo,
JP) ; FUJITSUKA; Masashi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
1000004839908 |
Appl. No.: |
16/645545 |
Filed: |
September 20, 2017 |
PCT Filed: |
September 20, 2017 |
PCT NO: |
PCT/JP2017/033894 |
371 Date: |
March 9, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 2600/2513 20130101;
F25D 2600/04 20130101; F25D 17/065 20130101; F25B 41/062 20130101;
F25D 29/00 20130101; F25D 2700/12 20130101 |
International
Class: |
F25D 17/06 20060101
F25D017/06; F25B 41/06 20060101 F25B041/06; F25D 29/00 20060101
F25D029/00 |
Claims
1. A refrigeration machine comprising: a refrigerant circuit in
which a compressor, a condenser, an expansion device, and a cooler
are connected by a refrigerant pipe; a first storage compartment
configured to store a cooling target; a fan configured to send air
from the cooler to the first storage compartment; a first
temperature sensor configured to detect a temperature of the first
storage compartment; and a second temperature sensor configured to
detect a temperature of the cooler, wherein the expansion device is
configured to have a degree of opening settable to a fully closed
state, and the degree of opening corresponds to the fully closed
state while the compressor is non-operational, the fan is
configured to continue to be operational while the compressor is
non-operational and when a temperature difference obtained by
subtracting a detection temperature of the second temperature
sensor from a detection temperature of the first temperature sensor
is larger than a first criterion value, the fan is configured to
become non-operational when transition is made, while the
compressor is non-operational, from a state in which the
temperature difference is larger than the first criterion value to
a state in which the temperature difference is smaller than the
first criterion value, the fan is configured to be non-operational
while the compressor is operational and when the temperature
difference is smaller than a second criterion value, the fan is
configured to become operational when transition is made, while the
compressor is operational, from a state in which the temperature
difference is smaller than the second criterion value to a state in
which the temperature difference is larger than the second
criterion value, and the expansion device includes at least one
capillary tube, and a valve configured to open and close a
refrigerant pipe communicating with the capillary tube.
2. The refrigeration machine according to claim 1, comprising a
plurality of storage compartments, wherein the first storage
compartment is a storage compartment having a lowest setting
temperature among the plurality of storage compartments.
3-4. (canceled)
5. The refrigeration machine according to claim 2, further
comprising a heat exchanger configured to exchange heat between
refrigerant passing through the expansion device and refrigerant in
a suction pipe connected to the compressor.
6. The refrigeration machine according to claim 5, wherein not only
while the compressor is non-operational but also while the
compressor is operational, the expansion device is configured to
continue to be in the fully closed state during a period in which
the detection temperature of the first temperature sensor is higher
than the detection temperature of the second temperature
sensor.
7. The refrigeration machine according to claim 2, wherein not only
while the compressor is non-operational but also while the
compressor is operational, the expansion device is configured to
continue to be in the fully closed state during a period in which
the detection temperature of the first temperature sensor is higher
than the detection temperature of the second temperature
sensor.
8. The refrigeration machine according to claim 1, further
comprising a heat exchanger configured to exchange heat between
refrigerant passing through the expansion device and refrigerant in
a suction pipe connected to the compressor.
9. The refrigeration machine according to claim 8, wherein not only
while the compressor is non-operational but also while the
compressor is operational, the expansion device is configured to
continue to be in the fully closed state during a period in which
the detection temperature of the first temperature sensor is higher
than the detection temperature of the second temperature
sensor.
10. The refrigeration machine according to claim 1, wherein not
only while the compressor is non-operational but also while the
compressor is operational, the expansion device is configured to
continue to be in the fully closed state during a period in which
the detection temperature of the first temperature sensor is higher
than the detection temperature of the second temperature sensor.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a U.S. national stage application of
International Application PCT/JP2017/033894 filed on Sep. 20, 2017,
the contents of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a refrigeration machine,
particularly, control of a cooler fan and an expansion valve in the
refrigeration machine when starting and stopping an operation of a
compressor.
BACKGROUND
[0003] As a refrigeration machine including a storage compartment,
Japanese Patent Laying-Open No. 2011-27325 (Patent Literature 1)
describes a refrigerator configured to control a temperature of the
storage compartment by rotating a cooler fan when the compressor is
non-operational.
[0004] The refrigerator described in Japanese Patent Laying-Open
No. 2011-27325 can cool the storage compartment without motive
power of the compressor by using the cooler having a low
temperature after the compressor becomes non-operational.
Therefore, a time interval until the operation of the compressor is
restarted due to an increased temperature of the storage
compartment can be long, thereby providing an effect of reducing an
average amount of consumption of power in both operational and
non-operational states of the refrigerator.
Patent Literature
[0005] PTL 1: Japanese Patent Laying-Open No. 2011-27325
[0006] In the refrigerator disclosed in Japanese Patent Laying-Open
No. 2011-27325, high-pressure refrigerant and low-pressure
refrigerant in a refrigeration cycle portion are readily mixed via
an expansion device immediately after the compressor becomes
non-operational. Hence, the temperature of the low-pressure
refrigerant at the cooler side is increased abruptly. Accordingly,
when a difference between the temperature of the cooler and the
temperature of the storage compartment is small, the temperature of
the cooler becomes more than or equal to the temperature of the
storage compartment immediately after the compressor becomes
non-operational. When the cooler fan is driven with the temperature
of the cooler being higher than the temperature of the storage
compartment, air having a temperature higher than the temperature
of the storage compartment flows into the storage compartment, with
the result that the temperature of the storage compartment is
increased. Consequently, a time until restarting of the operation
of the compressor becomes short, thus resulting in an increased
average amount of consumption of power, disadvantageously.
SUMMARY
[0007] The present invention has been made to solve the foregoing
problem, and has an object to provide a refrigeration machine that
can suppress increase in temperature of a storage compartment and
can reduce an average amount of consumption of power even when a
difference is small between a temperature of a cooler and the
temperature of the storage compartment.
[0008] A refrigeration machine according to the present disclosure
includes: a refrigerant circuit in which a compressor, a condenser,
an expansion device, and a cooler are connected by a refrigerant
pipe; a first storage compartment configured to store a cooling
target; a fan configured to send air from the cooler to the first
storage compartment; a first temperature sensor configured to
detect a temperature of the first storage compartment; and a second
temperature sensor configured to detect a temperature of the
cooler. The expansion device is configured to have a degree of
opening settable to a fully closed state, and the degree of opening
corresponds to the fully closed state while the compressor is
non-operational. The fan is configured to continue to be
operational while the compressor is non-operational and when a
temperature difference obtained by subtracting a detection
temperature of the second temperature sensor from a detection
temperature of the first temperature sensor is larger than a first
criterion value. The fan is configured to become non-operational
when transition is made, while the compressor is non-operational,
from a state in which the temperature difference is larger than the
first criterion value to a state in which the temperature
difference is smaller than the first criterion value. The fan is
configured to be non-operational while the compressor is
operational and when the temperature difference is smaller than a
second criterion value. The fan is configured to become operational
when transition is made, while the compressor is operational, from
a state in which the temperature difference is smaller than the
second criterion value to a state in which the temperature
difference is larger than the second criterion value.
[0009] According to the present invention, the temperature of the
storage compartment can be suppressed from being increased while
the compressor is non-operational. Hence, the non-operational
period of the compressor can be long. As a result, there can be
realized a refrigeration machine with a reduced average amount of
consumption of power including power for turning on and off a
compressor.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 is a schematic view of a refrigeration cycle of a
refrigeration machine according to a first embodiment.
[0011] FIG. 2 shows a first modification of the refrigeration
cycle.
[0012] FIG. 3 is a schematic view showing a refrigeration machine
having one storage compartment.
[0013] FIG. 4 is a flowchart for illustrating control in a normal
operation mode.
[0014] FIG. 5 is a waveform diagram showing a temperature change in
a comparative example in which an expansion device is fixed to an
open state.
[0015] FIG. 6 is a waveform diagram showing a temperature change
when the control of FIG. 4 is performed.
[0016] FIG. 7 is a flowchart for a condition of stopping an
operation of a cooler fan and a condition of driving the cooler fan
when sensor variations are taken into consideration.
[0017] FIG. 8 is a waveform diagram showing a temperature change
when the control of the flowchart of FIG. 7 is performed.
[0018] FIG. 9 shows an exemplary configuration of a refrigeration
machine having two storage compartments according to a second
embodiment.
[0019] FIG. 10 shows a modification representing a refrigeration
machine having three storage compartments.
[0020] FIG. 11 is a schematic view of a refrigeration cycle of a
refrigeration machine according to a third embodiment.
[0021] FIG. 12 is a schematic view showing an external appearance
of a flow path switching valve 9.
[0022] FIG. 13 shows a switching state of a flow path switching
valve 9.
[0023] FIG. 14 is a flowchart showing control performed in a fourth
embodiment.
[0024] FIG. 15 is a waveform diagram showing a temperature change
when the control of the flowchart of FIG. 14 is performed.
[0025] FIG. 16 is a schematic view showing a configuration of a
refrigeration machine according to a fifth embodiment.
DETAILED DESCRIPTION
[0026] The following describes embodiments of the present invention
with reference to figures in detail. It should be noted that the
same or corresponding portions in the figures are given the same
reference characters and are not described repeatedly.
First Embodiment
[0027] FIG. 1 is a schematic view of a refrigeration cycle of a
refrigeration machine according to a first embodiment. With
reference to FIG. 1, a refrigeration machine 100 includes: a
compressor 1 changeable in rotating speed; a condenser 2; an
expansion device 3; a cooler 4; a condenser fan 5; and a cooler fan
6. Compressor 1, condenser 2, expansion device 3, and cooler 4 are
communicated via a refrigerant pipe to form a refrigeration cycle.
In the first embodiment, an electronic expansion valve changeable
in a degree of opening in accordance with a control signal can be
used as expansion device 3, for example.
[0028] The following describes an operation of the refrigeration
cycle in the refrigeration machine according to the first
embodiment with reference to FIG. 1. High-temperature high-pressure
gas refrigerant discharged from compressor 1 passes through
condenser 2 (for example, an air heat exchanger). In condenser 2,
the refrigerant exchanges heat with external air around
refrigeration machine 100, and the refrigerant is condensed by heat
dissipation. The condensed high-pressure liquid refrigerant is
decompressed by expansion device 3 and becomes low-pressure
two-phase refrigerant. Then, the refrigerant flows into cooler 4.
In cooler 4, heat is exchanged between the refrigerant and
circulated air from the storage compartment. The circulated air
from the storage compartment is cooled by the refrigerant, and the
refrigerant becomes low-pressure gas refrigerant. Then, the
refrigerant in the form of low-pressure gas flows into compressor
1, is fed with a pressure, and is then discharged again.
[0029] FIG. 2 shows a first modification of the refrigeration
cycle. As shown in FIG. 2, an internal heat exchanger 11 may be
provided to exchange heat with refrigerant in a pipe connected to
the outlet of cooler 4 when decompressing the refrigerant in
expansion device 3. The temperature at the inlet of expansion
device 3 is higher than the temperature at the inlet of the suction
pipe connected to compressor 1. Hence, when internal heat exchanger
11 is provided, the refrigerant after introduced into expansion
device 3 is cooled by the refrigerant passing through the suction
pipe connected to compressor 1. Accordingly, a degree of dryness at
the inlet of cooler 4 has a value close to 0 and the refrigerant
therefore has a large amount of liquid phase, whereby cooler 4 can
be used effectively.
[0030] Next, the following describes a refrigeration machine
including a storage compartment and a refrigeration cycle. FIG. 3
is a schematic view showing a refrigeration machine having one
storage compartment. A structure of the refrigeration machine in
the first embodiment will be described with reference to FIG. 3. As
shown in FIG. 3, the refrigeration machine according to the first
embodiment includes: a storage compartment 13 (any one of a
vegetable compartment, a freezer compartment, and a cold
compartment); the above-described refrigeration cycle; and
temperature sensors 7, 8 respectively installed at storage
compartment 13 and cooler 4.
[0031] Based on a storage compartment temperature Tr and a cooler
temperature Te respectively obtained from temperature sensors 7, 8
as shown in FIG. 3, compressor 1, cooler fan 6, and expansion
device 3 are controlled as described below. In this case, the
installation locations of the sensors in FIG. 3 are exemplary, and
are not limited. For example, temperature sensor 7 may be installed
at an upper portion of storage compartment 13 as long as
temperature sensor 7 represents the temperature of storage
compartment 13. Moreover, temperature sensor 8 for the cooler may
be installed at any location as long as temperature sensor 8
represents the temperature of the cooler, such as the center of
cooler 4.
[0032] Next, a control method will be described. In the present
specification, a "normal operation mode" represents a state in
which compressor 1 is driven, expansion device 3 is open and cooler
fan 6 is driven to cool inside of storage compartment 13. A
behavior in the normal operation mode will be described.
[0033] FIG. 4 is a flowchart for illustrating control in the normal
operation mode. With reference to FIG. 3 and FIG. 4, while cooling
the inside of storage compartment 13 by operating compressor 1, the
temperature in storage compartment 13 is decreased gradually. In
order to maintain the temperature of storage compartment 13 around
a setting temperature, a criterion temperature Toff for stopping
the operation of compressor 1 is set. When storage compartment
temperature Tr becomes lower than Toff, further cooling is not
required. Hence, control device 20 make transition to determine to
stop the operation of compressor 1 (YES in step S1).
[0034] By stopping the operation of compressor 1 while maintaining
pressures at high-pressure portion and low-pressure portion of the
refrigeration cycle, loss can be reduced when restarting the
operation of compressor 1. Moreover, by using cooler 4 having a low
temperature, an amount of consumption of power can be reduced.
Hence, control device 20 fully closes expansion device 3 (step S2),
and stops the operation of compressor 1 (step S3).
[0035] When compressor 1 is non-operational, the low temperature
provided by the refrigeration cycle cannot be produced, with the
result that temperature Tr of storage compartment 13 is gradually
increased due to transfer of heat from external air. In order to
maintain temperature Tr of storage compartment 13 around the
setting temperature, a criterion temperature Ton for restarting the
operation of compressor 1 is set. When storage compartment
temperature Tr becomes more than or equal to criterion temperature
Ton (YES in step S4), cooling is required, with the result that
control device 20 makes transition to an operation for restarting
the operation of compressor 1 (step S8).
[0036] When storage compartment temperature Tr is less than or
equal to Ton (NO in step S4), control device 20 continuously
maintains compressor 1 to be non-operational with the inside of
storage compartment 13 being maintained to be cool. When compressor
1 is continuously maintained to be non-operational, control device
20 determines whether to continuously operate cooler fan 6 (step
S5).
[0037] When cooler temperature Te is lower than storage compartment
temperature Tr (YES in step S5), it can be determined that cooler 4
can be used to cool storage compartment 13. Hence, control device
20 operates only cooler fan 6 (step S6). On the other hand, when
cooler temperature Te is higher than storage compartment
temperature Tr (NO in step S5), it can be determined that cooler 4
cannot be used for cooling. Hence, control device 20 stops the
operation of cooler fan 6 (step S7). After the processes of step S6
or step S7 are ended and the process of steps S2 and S3 are
performed again, control device 20 determines again in step S4
whether to restart the operation of compressor 1.
[0038] When Tr.gtoreq.Ton is satisfied in step S4 (YES in S4),
control device 20 drives compressor 1 (step S8) and opens expansion
device 3 (step S9). Then, the pressure of the low-pressure portion
is decreased gradually. Here, control device 20 determines whether
or not cooler temperature Te is higher than storage compartment
temperature Tr (step S10). When cooler temperature Te is higher
than storage compartment temperature Tr (NO in S10), it can be
determined that cooler 4 is not sufficiently cooled, so that the
determination of step S10 is performed again after performing the
processes of steps S8 and S9. When cooler temperature Te is less
than or equal to storage compartment temperature Tr (YES in S10),
it can be determined that cooler 4 is sufficiently cooled. Hence,
control device 20 drives cooler fan 6 having been non-operational,
so as to send cool air to storage compartment 13 again.
[0039] FIG. 5 is a waveform diagram showing a temperature change in
a comparative example in which the expansion device is fixed to the
open state. In the control of the comparative example, the
expansion device is open. Hence, immediately after stopping the
operation of compressor 1, the high-pressure refrigerant and the
low-pressure refrigerant in the refrigeration cycle portion are
readily mixed via expansion device 3. Therefore, temperature Te of
the low-pressure refrigerant at the cooler 4 side is abruptly
increased at a time t2. Hence, when a difference is small between
the temperature of cooler 4 and temperature Tr of storage
compartment 13, temperature Te of cooler 4 becomes more than or
equal to storage compartment temperature Tr during a period of
times t2 to t3 immediately after stopping the operation of the
compressor. When the cooler fan is driven with cooler temperature
Te being higher than storage compartment temperature Tr, air having
a temperature higher than storage compartment temperature Tr flows
into storage compartment 13. Hence, storage compartment temperature
Tr is increased. As a result, it is necessary to stop the operation
of cooler fan 6 immediately after stopping the operation of
compressor 1. As a result of such control, the cooling source is
lost due to the mixing of the high-pressure refrigerant and the
low-pressure refrigerant in the refrigeration cycle portion, with
the result that a time until restarting of the operation of
compressor 1 becomes short and the average amount of consumption of
power is increased.
[0040] FIG. 6 is a waveform diagram showing a temperature change
when the control of FIG. 4 of the first embodiment is
performed.
[0041] In the control of the first embodiment, when compressor 1
becomes non-operational, expansion device 3 is fully closed (time
t11). By fully closing expansion device 3, the high-pressure
refrigerant does not flow into the low-pressure side, whereby the
low pressure can be maintained. Therefore, even when cooler fan 6
is maintained to be driven, air having a temperature more than or
equal to the storage compartment temperature can be prevented from
being supplied to storage compartment 13 for a while (times t11 to
t12).
[0042] When expansion device 3 is fully closed, cooler temperature
Te is not increased abruptly, and the state of Tr>Te is
maintained during the period of times t11 to t12. During this
period, cooler fan 6 can be driven to cool storage compartment 13.
However, by rotating cooler fan 6, air in storage compartment 13
warmed by food brought into storage compartment 13 and external air
around storage compartment 13 flows into cooler 4. Accordingly, the
liquid refrigerant is evaporated to gradually increase cooler
temperature Te (times t11 to t12). The increase of cooler
temperature Te leads to increase of storage compartment temperature
Tr.
[0043] When driving only cooler fan 6 with compressor 1 being
non-operational, cooler temperature Te coincides with storage
compartment temperature Tr after passage of a certain period of
time (time t12). In this state, storage compartment 13 cannot be
cooled even though cooler fan 6 is driven, thus resulting in a
meaningless operation. Hence, when Tr<Te is satisfied, the
operation of cooler fan 6 is stopped (times t12 to t13).
[0044] When compressor 1 and cooler fan 6 are non-operational,
storage compartment temperature Tr is increased because the cooling
source is lost. Moreover, the liquid refrigerant remaining in
cooler 4 is evaporated gradually to increase pressure in the pipe,
thus resulting in increase of cooler temperature Te. On this
occasion, expansion device 3 is in the fully closed state (times
t12 to t13). This is due to the following reason: by maintaining
the high pressure and low pressure while avoiding mixing of the
high-pressure refrigerant and the low-pressure refrigerant, on-off
loss is reduced when restarting the operation of compressor 1.
[0045] After storage compartment temperature Tr becomes more than
temperature Ton, control device 20 restarts the operation of
compressor 1 in order to cool storage compartment 13. When the
operation of compressor 1 is restarted, if cooler temperature Te is
higher than storage compartment temperature Tr, cooler fan 6 is
maintained to be non-operational (times t13 to t14). In this way,
cooler temperature Te is decreased abruptly.
[0046] When cooler temperature Te is decreased abruptly to satisfy
Te.gtoreq.Tr, even if cooler fan 6 is driven, air in the cooler
with a temperature less than or equal to storage compartment
temperature Tr can be sent securely to the inside of storage
compartment 13. Hence, cool air can be sent without increasing
storage compartment temperature Tr.
[0047] Here, in some case, temperature sensors 7, 8 have variations
and tolerances (margins) corresponding to the variations should be
provided to the determination process. For example, the condition
of the determination in the process of step S5 of FIG. 4 is not
limited to Tr.gtoreq.Te, and may be Tr-A.gtoreq.Te (where A is a
predetermined value) in consideration of influences of the sensor
variations. Moreover, the condition of operating cooler fan 6 in
step S10 of FIG. 4 is not limited to Te.ltoreq.Tr, and may be
Te.ltoreq.Tr-B (where B is a predetermined value) in consideration
of the influences of the sensor variations.
[0048] FIG. 7 is a flowchart for a condition of stopping the
operation of cooler fan 6 when compressor 1 is non-operational and
a condition of driving cooler fan 6 after restarting the operation
of compressor 1, in the case where the sensor variations are taken
into consideration. The flowchart of FIG. 7 is different from the
flowchart of FIG. 4 in that steps S5A, S10A are performed instead
of steps S5, S10. Hence, steps S5A, S10A will be hereinafter
described and the other parts will not be described repeatedly.
[0049] In step S5A, control device 20 compares temperature Tr of
storage compartment 13 with cooler temperature Te to determine
whether to make cooler fan 6 operational or non-operational. On
this occasion, tolerance A is provided in consideration of the
variations of the temperature sensors. In step S5A, when
Tr-A.gtoreq.Te is satisfied (YES in S5A), the process proceeds to
step S6, whereas when Tr-A.gtoreq.Te is not satisfied (NO in S5A),
the process proceeds to step S7. By taking tolerance A into
consideration, cooler fan 6 can become non-operational securely
before storage compartment temperature Tr becomes higher than
cooler temperature Te.
[0050] In step S10A, after restarting the operation of compressor
1, control device 20 compares storage compartment temperature Tr
with cooler temperature Te to determine whether to drive cooler fan
6. On this occasion, tolerance B is provided in consideration of
the variations of temperature sensors 7, 8. When Te.ltoreq.Tr-B is
not satisfied (NO in S10A), it is determined that the cooler is not
sufficiently cooled. Hence, the process proceeds to step S8 and
control device 20 maintains the non-operational state of cooler fan
6. When Te.ltoreq.Tr-B is satisfied, it is determined that cooler 4
is sufficiently cooled. Hence, the process proceeds to step S11 and
control device 20 drives cooler fan 6 to send cool air to storage
compartment 13.
[0051] FIG. 8 is a waveform diagram showing a temperature change
when the control of the flowchart of FIG. 7 is performed. In the
waveform diagram of FIG. 8, as compared with the waveform diagram
of FIG. 6, a time t12A, which corresponds to a timing to stop the
operation of cooler fan 6, is close to time t11, and a time t14A,
which corresponds to a timing to restart the operation of cooler
fan 6, is further away from time t13.
[0052] Thus, by taking tolerances A, B into consideration, cooler
fan 6 can be securely prevented from being driven when cooler
temperature Te is higher than storage compartment temperature
Tr.
Second Embodiment
[0053] In a second embodiment, the following describes a case where
two storage compartments are provided. A refrigeration cycle of the
refrigeration machine according to the second embodiment is the
same as that described in the first embodiment with reference to
FIG. 1 or FIG. 2, and therefore will not be described.
[0054] The refrigeration machine according to the second embodiment
has two or more storage compartments that can be set to different
setting temperatures. FIG. 9 shows an exemplary configuration of a
refrigeration machine having two storage compartments according to
the second embodiment. In FIG. 9, a feature lies in that the
temperature of a storage compartment 13B is lower than that of a
storage compartment 13A.
[0055] The temperature of storage compartment 13A is controlled by
a damper 15 provided in an air path that connects between cooler 4
and storage compartment 13A. For example, control device 20 opens
or closes damper 15 in accordance with an output value of
temperature sensor 7A of storage compartment 13A. By opening damper
15, cooling air flows into storage compartment 13A, with the result
that temperature TrA of storage compartment 13A is decreased.
Moreover, by closing damper 15, the cooling air cannot flow into
storage compartment 13A, with the result that temperature TrA of
storage compartment 13A is increased due to transfer of heat from
external air. Hence, control device 20 can adjust the temperature
of storage compartment 13A by opening or closing damper 15 based on
an output value of temperature sensor 7A.
[0056] No damper is provided in an air path from cooler 4 to
storage compartment 13B. This is due to the following reason: since
the setting temperature of storage compartment 13B is low, cooling
air needs to always flow thereinto. For example, control device 20
adjusts the temperature of storage compartment 13B by controlling
the frequency and ON-OFF of compressor 1 in accordance with an
output value of temperature sensor 7B of storage compartment
13B.
[0057] Moreover, storage compartment temperature Tr described in
the control flow diagram (each of FIG. 4 and FIG. 7) is also
applicable to temperature TrB of storage compartment 13B in the
second embodiment in which two or more storage compartments are
provided. By employing storage compartment temperature Tr of the
control flow diagram (each of FIG. 4 and FIG. 7) as temperature TrB
of storage compartment 13B, the temperature of storage compartment
13B having the low setting temperature can be prevented from being
increased greatly from the setting temperature.
[0058] FIG. 10 shows a modification representing a refrigeration
machine having three storage compartments. In the modification of
the second embodiment as shown in FIG. 10, a configuration close to
that of a general refrigerator will be described as one example of
the refrigeration machine. The refrigeration machine shown in FIG.
10 includes storage compartments 13A to 13C. For example, storage
compartment 13A disposed at an upper stage is a cold compartment,
storage compartment 13B disposed at a middle stage is a freezer
compartment, and storage compartment 13C disposed at the lower
stage is a vegetable compartment. The setting temperature of
storage compartment 13B is set to be lower than the setting
temperatures of storage compartment 13A and storage compartment
13C. Compressor 1 and condenser 2 are disposed at the bottom
portion and rear surface of storage compartment 13C, and cooler 4
and cooler fan 6 are disposed in an air path at the rear surface of
storage compartment 13B.
[0059] In such a configuration, the same control is applicable with
storage compartment temperature Tr described in the control flow
diagram (each of FIG. 4 and FIG. 7) being employed as setting
temperature TrB of storage compartment 13B.
Third Embodiment
[0060] FIG. 11 is a schematic view of a refrigeration cycle of a
refrigeration machine according to a third embodiment. With
reference to FIG. 11, a refrigeration machine 100B includes: a
compressor 1 changeable in rotating speed; a condenser 2; an
expansion device 3B; a cooler 4; a condenser fan 5; and a cooler
fan 6. Compressor 1, condenser 2, expansion device 3B, and cooler 4
are communicated via a refrigerant pipe to form a refrigeration
cycle.
[0061] Expansion device 3B includes a flow path switching valve 9
and capillary tubes 31, 32. Expansion device 3B employs capillary
tubes 31, 32, which are pipes having small diameters to provide a
pressure difference. An amount of contraction of each of capillary
tubes 31, 32 is fixed. Flow path switching valve 9 has one
inlet-side flow path P1 and two outlet-side flow paths P2, P3.
[0062] FIG. 12 is a schematic view showing an external appearance
of flow path switching valve 9. FIG. 13 shows a switching state of
flow path switching valve 9. It should be noted that each of FIG.
12 and FIG. 13 shows an example in which two capillary tubes 31, 32
are connected to outlet-side flow paths P2, P3 of flow path
switching valve 9, respectively; however, the number of the
capillary tubes may be 1, 3, or more and is not limited to 2.
[0063] By rotating and moving the valve body in flow path switching
valve 9 to connect the inlet-side and outlet-side flow paths, a
manner of flow of the refrigerant can be switched. FIG. 13
illustrates: a case where the refrigerant flows from inlet-side
flow path P1 to the two flow paths (P2+P3); the fully closed state
of the expansion device in step S2 of the control flow diagram of
each of FIG. 4 and FIG. 7; a case where the refrigerant flows from
inlet-side flow path P1 to outlet-side flow path P3; and a case
where the refrigerant flows from inlet-side flow path P1 to
outlet-side flow path P2.
[0064] In the case of the flow path switching valve shown in FIG.
13, by rotating valve body 36 with respect to a rotation shaft 35,
it is possible to select to fully close the expansion device or
select any of the plurality of connected capillary tubes 31, 32.
Hence, the amount of contraction of the path for the refrigerant
can be changed. That is, flow path switching valve 9 and capillary
tubes 31, 32 function as the expansion device.
[0065] The other configurations and control flow diagram of the
third embodiment are the same as those of the first embodiment, and
therefore are not described repeatedly.
[0066] It should be noted that as shown in FIG. 11, an internal
heat exchanger 11B may be provided to exchange heat between the
refrigerant flowing in a pipe (which may be capillary tubes 31, 32)
connected to the inlet of cooler 4 and the refrigerant to be
suctioned by compressor 1, when decompressing the refrigerant in
expansion device 3.
Fourth Embodiment
[0067] A feature of a fourth embodiment lies in that compressor 1
is driven with expansion device 3 closed in the operation after
compressor 1 becomes non-operational. By controlling compressor 1
and expansion device 3 in this way, pressure at the low pressure
portion can be decreased abruptly, whereby cooler fan 6 can be
driven promptly.
[0068] FIG. 14 is a flowchart showing the control performed in the
fourth embodiment. In comparison with the flowchart of FIG. 4, in
the flowchart of FIG. 14, the process of opening the expansion
valve in step S9 is omitted and a process of step S20 is added
instead. After S8 of restarting the operation of compressor 1,
control device 20 compares cooler temperature Te with storage
compartment temperature Tr immediately in S10. When Te.ltoreq.Tr is
satisfied in step S10, the process proceeds to step S20 to open
expansion device 3. The other parts of the flowchart of FIG. 14 are
the same as those of the flowchart of FIG. 4, and therefore will
not be described repeatedly.
[0069] FIG. 15 is a waveform diagram showing a temperature change
when the control of the flowchart of FIG. 14 is performed. In the
waveform diagram of FIG. 15, compressor 1 is operated and expansion
device 3 is controlled to be in the closed state during a period of
times t13 to t14. By controlling in this way, pressure of the
low-pressure portion connected to the suction side of compressor 1
can be decreased promptly.
Fifth Embodiment
[0070] FIG. 16 is a schematic view showing a configuration of a
refrigeration machine according to a fifth embodiment. The fifth
embodiment represents an exemplary food showcase placed in a shop
or the like. For a refrigeration cycle, the configuration shown in
each of FIG. 1, FIG. 2, and FIG. 11 is applicable. Also in the case
of such a food showcase, the same effect as that in each of the
first to fourth embodiments can be obtained by performing the
control of each of FIG. 4, FIG. 7, and FIG. 14.
CONCLUSION
[0071] Finally, with reference to representative figures again, the
first to fifth embodiments will be summarized.
[0072] With reference to FIG. 3, a refrigeration machine according
to the present disclosure includes: a refrigerant circuit in which
a compressor 1, a condenser 2, an expansion device 3, and a cooler
4 are connected by a refrigerant pipe; a first storage compartment
13 configured to store a cooling target; a fan 6 configured to send
air from cooler 4 to first storage compartment 13; a first
temperature sensor 7 configured to detect a temperature Tr of first
storage compartment 13; and a second temperature sensor 8
configured to detect a temperature Te of cooler 4. Expansion device
3 is configured to have a degree of opening settable to a fully
closed state, and the degree of opening corresponds to the fully
closed state while compressor 1 is non-operational. As shown in S5
of FIG. 4 or S5A of FIG. 7, fan 6 is configured to continue to be
operational while compressor 1 is non-operational and when a
temperature difference .DELTA.T obtained by subtracting a detection
temperature Te of second temperature sensor 8 from a detection
temperature Tr of first temperature sensor 7 is larger than a first
criterion value (0 or a tolerance A). Fan 6 is configured to become
non-operational when transition is made, while compressor 1 is
non-operational, from a state in which temperature difference
.DELTA.T is larger than the first criterion value to a state in
which temperature difference .DELTA.T is smaller than the first
criterion value. As shown in S10 of FIG. 4 or S10A of FIG. 7, fan 6
is configured to be non-operational while compressor 1 is
operational and when temperature difference .DELTA.T is smaller
than a second criterion value (0 or a tolerance B). Fan 6 is
configured to become operational when transition is made, while
compressor 1 is operational, from a state in which temperature
difference .DELTA.T is smaller than the second criterion value to a
state in which temperature difference .DELTA.T is larger than the
second criterion value.
[0073] Preferably, as shown in FIG. 10, the refrigeration machine
includes a plurality of storage compartments 13A to 13C. The first
storage compartment is a storage compartment 13B having a lowest
setting temperature among the plurality of storage
compartments.
[0074] Preferably, as shown in FIG. 1 and FIG. 2, expansion device
3 is an expansion valve changeable in degree of opening.
[0075] Preferably, as shown in FIG. 11, expansion device 3B
includes a capillary tube 31, 32, and a flow path switching valve 9
configured to open and close a refrigerant pipe (flow path P2, P3)
communicating with capillary tube 31, 32.
[0076] Preferably, as shown in FIG. 2 and FIG. 11, the
refrigeration machine further includes an internal heat exchanger
11, 11B configured to exchange heat between refrigerant passing
through expansion device 3, 3B and refrigerant in a suction pipe
connected to compressor 1.
[0077] Preferably, as shown in FIG. 14 and FIG. 15, not only while
compressor 1 is non-operational but also while compressor 1 is
operational, expansion device 3 or 3B is configured to continue to
be in the fully closed state during a period in which detection
temperature Tr of first temperature sensor 7 is higher than
detection temperature Te of second temperature sensor 8.
Effect
[0078] According to the refrigeration machine according to each of
the first to fifth embodiments, the storage compartment temperature
can be suppressed from being increased while compressor 1 is
non-operational. Hence, a non-operational period of the compressor
can be long. As a result, an average amount of consumption of power
including power for turning on and off compressor 1 can be
reduced.
[0079] Moreover, in the refrigeration machine according to each of
the first to fifth embodiments, the difference between the high
pressure of the refrigerant and the low pressure of the refrigerant
can be maintained during the non-operational period of compressor
1. As a result, when restarting the operation of compressor 1, it
is not necessary to make the difference between the high pressure
and the low pressure again, whereby energy loss in the
refrigeration cycle when turning on/off compressor 1 can be
reduced. Accordingly, the amount of consumption of power of the
refrigeration machine can be reduced.
[0080] Further, in the refrigeration machine according to each of
the first to fifth embodiments, air having a temperature more than
or equal to storage compartment temperature Tr can be prevented
from being sent to the storage compartment by driving cooler fan 6
with cooler 4 having not been cooled yet immediately after
restarting the operation of compressor 1. As a result, temperature
Tr of the storage compartment can be prevented from being
increased, whereby the temperature of food placed on the storage
compartment can be prevented from being increased. As a result,
quality of the food can be secured.
[0081] Moreover, the refrigeration machine according to each of the
first to fifth embodiments provides an energy saving effect by
causing cooler fan 6, expansion device 3, and compressor 1 to
perform the series of operations in the order described above. For
example, when cooler fan 6 is not operated in period Pd2 of t11 to
t12 of FIG. 6 or t11 to t12A of FIG. 8, warm air in the storage
compartment does not reach cooler 4, with the result that
temperature Te of cooler 4 does not become more than storage
compartment temperature Tr.
[0082] Moreover, when expansion device 3 is not fully closed in
period Pd2 of t11 to t12 of FIG. 6 or t11 to t12A of FIG. 8, the
high pressure and the low pressure are immediately changed to be
equal to each other just after compressor 1 becomes
non-operational. Accordingly, cooler temperature Te becomes more
than or equal to storage compartment temperature Tr. Hence, loss is
caused due to the high pressure and the low pressure being changed
to be equal to each other, thus resulting in decreased energy
saving. Hence, energy saving is attained only by controlling
compressor 1, cooler fan 6, and expansion device 3 in the series of
flows described in order of periods Pd1 to Pd5 of each of FIG. 6,
FIG. 8, and FIG. 15.
[0083] The embodiments disclosed herein are illustrative and
non-restrictive in any respect. The scope of the present invention
is defined by the terms of the claims, rather than the embodiments
described above, and is intended to include any modifications
within the scope and meaning equivalent to the terms of the
claims.
* * * * *