U.S. patent application number 17/417816 was filed with the patent office on 2022-02-24 for method for controlling operation of ice-making machine.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. The applicant listed for this patent is DAIKIN INDUSTRIES, LTD.. Invention is credited to Takamasa ITOU, Akihiro KAJIMOTO, Kouichi KITA, Kazuhiko NISHIHARA, Takeo UENO, Yuuji YAMANAKA.
Application Number | 20220057130 17/417816 |
Document ID | / |
Family ID | 1000006012991 |
Filed Date | 2022-02-24 |
United States Patent
Application |
20220057130 |
Kind Code |
A1 |
KITA; Kouichi ; et
al. |
February 24, 2022 |
METHOD FOR CONTROLLING OPERATION OF ICE-MAKING MACHINE
Abstract
A method for controlling an operation of an ice-making machine
configured to make ice by cooling a medium to be cooled, through
heat exchange with a refrigerant. The method includes increasing an
evaporation temperature of the refrigerant to be supplied to the
ice-making machine when a drive current for an ice scraper of the
ice-making machine is more than a first current value.
Inventors: |
KITA; Kouichi; (Osaka-shi,
JP) ; KAJIMOTO; Akihiro; (Osaka-shi, JP) ;
NISHIHARA; Kazuhiko; (Osaka-shi, JP) ; ITOU;
Takamasa; (Osaka-shi, JP) ; YAMANAKA; Yuuji;
(Osaka-shi, JP) ; UENO; Takeo; (Osaka-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIKIN INDUSTRIES, LTD. |
Osaka-shi, Osaka |
|
JP |
|
|
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka-shi, Osaka
JP
|
Family ID: |
1000006012991 |
Appl. No.: |
17/417816 |
Filed: |
August 28, 2019 |
PCT Filed: |
August 28, 2019 |
PCT NO: |
PCT/JP2019/033661 |
371 Date: |
June 24, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 49/022 20130101;
F25C 2600/04 20130101; F25C 1/147 20130101; F25C 5/12 20130101 |
International
Class: |
F25C 5/12 20060101
F25C005/12; F25B 49/02 20060101 F25B049/02; F25C 1/147 20060101
F25C001/147 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2018 |
JP |
2018-245322 |
Claims
1. A method for controlling an operation of an ice-making machine
configured to make ice by cooling a medium to be cooled, through
heat exchange with a refrigerant in a refrigerant circuit including
a compressor, the method comprising: increasing an evaporation
temperature of the refrigerant to be supplied to the ice-making
machine when a drive current for an ice scraper of the ice-making
machine is more than a first current value, stopping the operation
of the compressor and continuing the operation of the ice scraper
when the drive current is more than a second current value that is
larger than the first current value, restarting the operation of
the compressor when the drive current decreases to a predetermined
value.
2. The method according to claim 1, comprising: increasing the
evaporation temperature stepwise in accordance with an excess of
the current.
3. (canceled)
4. A method for controlling an operation of an ice-making machine
configured to make ice by cooling a medium to be cooled, through
heat exchange with a refrigerant in a refrigerant circuit including
a compressor, the method comprising: increasing an evaporation
temperature of the refrigerant to be supplied to the ice-making
machine when a pressure difference between a pressure of the medium
to be cooled at an inlet of the ice-making machine and a pressure
of the medium to be cooled at an outlet of the ice-making machine
is more than a first pressure value, stopping the operation of the
compressor and continuing the operation of the ice scraper when the
pressure difference is more than a second pressure value that is
larger than the first pressure value, restarting the operation of
the compressor when the pressure difference decreases to a
predetermined value.
5. The method according to claim 4, comprising: increasing the
evaporation temperature stepwise in accordance with an excess of
the pressure difference.
6. (canceled)
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a method for controlling
an operation of an ice-making machine. More specifically, the
present disclosure relates to a method for controlling an operation
of an ice-making machine configured to make sherbet-like ice
slurry.
BACKGROUND ART
[0002] Sherbet-like ice slurry has occasionally been used for
refrigerating fish and the like. Heretofore, for example, a double
pipe ice-making machine including an inner pipe and an outer pipe
has been known as an apparatus for making such ice slurry (refer
to, for example, Patent Literature 1). An ice-making system that
includes such an ice-making machine also includes a tank for
storing a medium to be cooled, such as seawater. The medium to be
cooled is supplied from the tank to an inner pipe of the ice-making
machine, and ice slurry is made through heat exchange of the medium
to be cooled with a refrigerant supplied to an annular space
between an outer pipe and the inner pipe of the ice-making machine.
The ice slurry thus made is returned to the tank.
CITATION LIST
Patent Literature
[0003] Patent Literature 1: Japanese Patent No. 3,888,789
SUMMARY
Solution to Problem
[0004] A method for controlling an operation of an ice-making
machine (hereinafter, also simply referred to as an "operation
control method") according to a first aspect of the present
disclosure has the following configurations.
[0005] (1) A method for controlling an operation of an ice-making
machine configured to make ice by cooling a medium to be cooled,
through heat exchange with a refrigerant,
[0006] the method including:
[0007] increasing an evaporation temperature of the refrigerant to
be supplied to the ice-making machine when a drive current for an
ice scraper of the ice-making machine is more than a first current
value.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a schematic configuration diagram of an exemplary
ice-making system including an ice-making machine to which an
operation control method according to the present disclosure is
applied.
[0009] FIG. 2 is a side view of the ice-making machine illustrated
in FIG. 1.
[0010] FIG. 3 is a sectional view of an ice scraper in the
ice-making machine illustrated in FIG. 2.
[0011] FIG. 4 illustrates exemplary control on an evaporation
temperature in an operation control method according to a first
embodiment.
[0012] FIG. 5 is a graph of a behavior of a motor current in the
operation control method according to the first embodiment.
[0013] FIG. 6 illustrates exemplary control on an evaporation
temperature in an operation control method according to a second
embodiment.
DESCRIPTION OF EMBODIMENTS
[0014] Hereinafter, a specific description will be given of an
operation control method according to the present disclosure with
reference to the accompanying drawings. The present disclosure is
not limited to the following exemplary description, and all changes
that fall within metes and bounds of the claims, or equivalence
such metes and bounds thereof are therefore intended to be embraced
by the claims.
Ice-Making System
[0015] First, a description will be given of an exemplary
ice-making system including an ice-making machine to which an
operation control method according to the present disclosure is
applied.
[0016] FIG. 1 is a schematic configuration diagram of an ice-making
system A including an ice-making machine 1 to which the operation
control method according to the present disclosure is applied. FIG.
2 is a side view of the ice-making machine 1 illustrated in FIG. 1.
In the ice-making system A, the ice-making machine 1 continuously
makes ice slurry from seawater (raw material) stored in a seawater
tank (to be described later), and returns the ice slurry thus made
to the seawater tank. The term "ice slurry" refers to sherbet-like
ice in which fine ice is formed and suspended within water or a
solution of water. The ice slurry is also called slurry ice, ice
slurry, slurry ice, sluff ice, or liquid ice. The ice-making system
A is capable of continuously making seawater-based ice slurry. The
ice-making system A is therefore introduced in, for example, a
fishing boat or a fishing port, and the ice slurry returned to the
seawater tank is used for, for example, keeping fresh fish cool. In
the illustrated ice-making system A, a resupply pump (not
illustrated) resupplies new seawater to the seawater tank in
accordance with an amount of the used (consumed) ice slurry.
[0017] The ice-making system A adopts seawater as a medium to be
cooled. The ice-making system A also includes, in addition to the
ice-making machine 1 serving as a part of a utilization-side heat
exchanger, a compressor 2, a heat source-side heat exchanger 3, a
four-way switching valve 4, a utilization-side expansion valve 5, a
heat source-side expansion valve 6, a superheater 7, a receiver 8,
a seawater tank (a reservoir tank) 9, and a pump 10. The ice-making
machine 1, the compressor 2, the heat source-side heat exchanger 3,
the four-way switching valve 4, the utilization-side expansion
valve 5, the heat source-side expansion valve 6, the superheater 7,
and the receiver 8 each serve as a part of a refrigeration
apparatus. These apparatuses or members are interconnected via
pipes to form a refrigerant circuit. The ice-making machine 1, the
seawater tank 9, and the pump 10 are interconnected via pipes to
form a seawater circuit. In the ice-making system A, each of the
ice-making machine 1, the compressor 2, the heat source-side heat
exchanger 3, the four-way switching valve 4, the utilization-side
expansion valve 5, the heat source-side expansion valve 6, the
superheater 7, the receiver 8, and the like is an equipment-side
element, and each of the seawater tank 9, the pump 10, the pipes,
and the like is a facility-side element.
[0018] The ice-making system A also includes a control apparatus
30. The control apparatus 30 includes a central processing unit
(CPU) and a memory such as a random access memory (RAM) or a read
only memory (ROM). The control apparatus 30 achieves various kinds
of control concerning an operation of the ice-making system A,
including the operation control according to the present
disclosure, in such a manner that the CPU executes a computer
program stored in the memory.
[0019] In a normal ice-making operation, the four-way switching
valve 4 is maintained at a state indicated by a solid line in FIG.
1. The compressor 2 discharges a high-temperature and high-pressure
gas refrigerant. The gas refrigerant flows into the heat
source-side heat exchanger 3 that functions as a condenser, via the
four-way switching valve 4. The heat source-side heat exchanger 3
condenses and liquefies the gas refrigerant by heat exchange with
air provided by a fan 11. The liquefied refrigerant then flows into
the utilization-side expansion valve 5 via the heat source-side
expansion valve 6 in a fully open state and the receiver 8. The
utilization-side expansion valve 5 decompresses the refrigerant to
a predetermined low pressure. The low-pressure refrigerant then
flows into an annular space 14 between an inner pipe 12 and an
outer pipe 13 each serving as a part of an evaporator E of the
ice-making machine 1, through a refrigerant inlet pipe to be
described later.
[0020] In the annular space 14, the refrigerant evaporates by heat
exchange with the seawater which the pump 10 supplies into the
inner pipe 12. The seawater is cooled by the evaporation of the
refrigerant. The seawater then returns to the seawater tank 8 via
the inner pipe 12. The refrigerant gasifies by the evaporation in
the ice-making machine 1. Thereafter, the refrigerant is sucked
into the compressor 2. At this time, if the refrigerant that is not
sufficiently evaporated in the ice-making machine 1 and slightly
left liquefied is sucked into the compressor 2, an abrupt increase
in pressure inside a compressor cylinder (liquid compression) or a
decrease in viscosity of a refrigerating machine oil causes a
failure in the compressor 2. In order to protect the compressor 2,
the refrigerant from the ice-making machine 1 is heated by the
superheater 7 before being sucked into the compressor 2. The
superheater 7 is of a double pipe type. The refrigerant from the
ice-making machine 1 is superheated when passing a space between an
inner pipe and an outer pipe of the superheater 7. The refrigerant
thus superheated then returns to the compressor 2.
[0021] If the flow of the seawater is stagnated in the inner pipe
12 of the ice-making machine 1, the ice is accumulated in the inner
pipe 12 (ice accumulation) to hinder the operation of the
ice-making machine 1. In this case, a defrosting operation (a
heating operation) is performed for melting the ice in the inner
pipe 12. At this time, the four-way switching valve 4 is maintained
at a state indicated by a broken line in FIG. 1. The compressor 2
discharges the high-temperature and high-pressure gas refrigerant.
The gas refrigerant flows into the annular space 14 between the
inner pipe 12 and the outer pipe 13 of the ice-making machine 1 via
the four-way switching valve 4. In the annular space 14, the gas
refrigerant condenses and liquefies by heat exchange with the
ice-containing seawater in the inner pipe 12. The liquefied
refrigerant then flows into the heat source-side expansion valve 6
via the utilization-side expansion valve 5 in a fully open state
and the receiver 8. The heat source-side expansion valve 6
decompresses the liquefied refrigerant to a predetermined low
pressure. Thereafter, the refrigerant flows into the heat
source-side heat exchanger 3 functioning as an evaporator. During
the defrosting operation, in the heat source-side heat exchanger 3
functioning as an evaporator, the refrigerant gasifies by heat
exchange with air provided by the fan 11. Thereafter, the
refrigerant is sucked into the compressor 2.
[0022] The ice-making machine 1 is a portrait-oriented double pipe
ice-making machine that includes the evaporator E including the
inner pipe 12 and the outer pipe 13 whose axes extend horizontally,
and an ice scraper to be described later. The evaporator E is of a
flooded type, in which most of the annular space 14 between the
inner pipe 12 and the outer pipe 13 is filled with the liquid
refrigerant. The evaporator E thus enhances heat exchange
efficiency of the refrigerant with the seawater. In addition, when
most of the annular space 14 is filled with the liquid refrigerant,
the refrigerating machine oil is easily discharged from the
flooded-type evaporator. The refrigerating machine oil returns to
the compressor 2 to compensate for unsatisfactory lubrication of
the compressor 2, leading to improvement in reliability.
[0023] The inner pipe 12 is an element through which the seawater
serving as a medium to be cooled passes. The inner pipe 12 is made
of a metal material such as stainless steel or iron. The inner pipe
12 has a cylindrical shape, and is disposed in the outer pipe 13.
The inner pipe 12 has two ends that are closed. In the inner pipe
12, the ice scraper 15 is disposed to scrape sherbet-like ice
slurry off an inner peripheral face of the inner pipe 12 and to
disperse the sherbet-like ice slurry in the inner pipe 12. The
inner pipe 12 is connected at its first axial end (the right side
in FIG. 2) to a seawater inlet pipe 16 through which the seawater
is supplied into the inner pipe 12, and is also connected at its
second axial end (the left side in FIG. 2) to a seawater outlet
pipe 17 through which the seawater is discharged from the inner
pipe 12.
[0024] The outer pipe 13 has a cylindrical shape, and is made of a
metal material such as stainless steel or iron as in the inner pipe
12. The outer pipe 13 is connected at its lower side to a plurality
of refrigerant inlet pipes 18 (three refrigerant inlet pipes 18 in
FIG. 2), and is also connected at its upper side to a plurality of
refrigerant outlet pipes 19 (two refrigerant outlet pipes 19 in
FIG. 2). Each of the refrigerant inlet pipes 18 has on its upper
end a refrigerant supply port 20 through which the refrigerant is
supplied into the annular space 14. Each of the refrigerant outlet
pipes 19 has on its lower end a refrigerant discharge port 21
through which the refrigerant is discharged from the annular space
14.
[0025] As illustrated in FIGS. 2 and 3, the ice scraper 15 includes
a shaft 22, a support bar 23, a blade 24, and a motor 26. The shaft
22 has a second axial end that extends outward from a flange 25 on
the second axial end of the inner pipe 12. The shaft 22 is
connected at the second axial end to the motor 26 serving as a part
of a drive unit for driving the shaft 22. The motor 26 is provided
with an ammeter 31 that detects a drive current of the motor 26 and
transmits the drive current to the control apparatus 30. The ice
scraper 15 includes a plurality of the support bars 23 disposed
upright on a peripheral face of shaft 22 at predetermined spacings,
and a plurality of blades 24 respectively mounted to the distal
ends of the support bars 23. Each of the blades 24 is, for example,
a band plate-shaped member made of a synthetic resin. Each of the
blades 24 has a tapered side edge directed forward in its
rotational direction.
[0026] The annular space 14 is defined with an outer peripheral
face of the inner pipe 12 and an inner peripheral face of the outer
pipe 13 to form refrigerant paths that extend from the refrigerant
supply ports 20 on the lower side of the outer pipe 13 to the
refrigerant discharge ports 21 on the upper side of the outer pipe
13.
Operation Control Method
[0027] Next, a description will be given of a method for
controlling an operation of the ice-making machine 1 in the
ice-making system A. More specifically, a description will be given
of an operation control method that involves changing operating
conditions of the ice-making machine 1, stopping the ice-making
machine 1, or restarting the ice-making machine 1, based on an ice
packing factor in the seawater tank 9.
First Embodiment
[0028] In the ice-making system A, as the ice packing factor IPF in
the seawater tank 9 increases through the operation of the
ice-making machine 1, the amount of ice to be discharged from the
seawater tank 9 increases, and the amount of ice in the inner pipe
12 of the ice-making machine 1 also increases. The increase in
amount of ice in the inner pipe 12 causes an increase in driving
torque of the motor 26 in the ice scraper 15 that scrapes the
sherbet-like ice slurry off the inner peripheral face of the inner
pipe 12. The increase in driving torque causes an increase in drive
current of the motor 26. In the first embodiment, the operation of
the ice-making machine 1 is controlled using a drive current value
of the motor 26 in the ice scraper 15, the drive current value
being detected by the ammeter 31 and transmitted to the control
apparatus 30.
[0029] If the ice is excessively retained in the seawater tank 9
due to the increase in ice packing factor IPF of the seawater in
the seawater tank 9, the seawater containing a large amount of ice
flows into the ice-making machine 1, so that the current value of
the motor 26 in the ice scraper 15 becomes larger than usual. In
the first embodiment, when the current of the motor 26 exceeds a
first current value, an evaporation temperature of the refrigerant
to be supplied to the ice-making machine 1 is increased.
[0030] FIG. 4 illustrates exemplary control on the evaporation
temperature in the operation control method according to the first
embodiment. In FIG. 4, the vertical axis indicates a magnification
of the evaporation temperature of the refrigerant in the evaporator
E, that is, a ratio of the evaporation temperature to a normal
evaporation temperature to be described later. In this control
example, when the current value detected by the ammeter 31 is equal
to or less than 6 A, the evaporation temperature is set at a normal
set temperature t0 (e.g., -15.degree. C.). In the first embodiment,
when the current value exceeds the first current value, that is, 6
A, the evaporation temperature of the refrigerant to be supplied
into the evaporator E is increased. More specifically, in the first
embodiment, the evaporation temperature is set higher stepwise in
accordance with an excess of the current. For example, when the
current value is more than 6 A, but is equal to or less than 7 A,
the operation is controlled to set the evaporation temperature 0.9
times as low as the normal evaporation temperature t0. In addition,
when the current value is more than 7 A, but is equal to or less
than 8 A, the operation is controlled to set the evaporation
temperature 0.8 times as small as the normal evaporation
temperature t0. The amount of ice made by the ice-making machine 1
is decreased in such a manner that the evaporation temperature is
set higher than the normal value in accordance with the increase in
current value.
[0031] In the first embodiment, when the current value exceeds a
second current value (e.g., 11 A) larger than the first current
value, a thermostat is forcibly turned off to stop the operation of
the ice-making machine 1. In other words, the operation of the
compressor 2 is stopped to stop the circulation of the refrigerant
through the refrigerant circuit. It should be noted that the ice
scraper 15 is continuously operated even when the thermostat is
forcibly turned off. After the thermostat is forcibly turned off,
when the current value of the motor 26 decreases to a certain
value, for example, 9 A, the thermostat, which has been forcibly
turned off, is turned on again to restart the operation of the
compressor 2.
[0032] FIG. 5 is a graph of the behaviors of a current value in a
case where the operation control according to the first embodiment
is performed and the behaviors of a current value in a case where
the operation control is not performed (the conventional art). In
FIG. 5, the horizontal axis indicates a time (t), and the vertical
axis indicates a current value (A) of the motor 26 in the ice
scraper 15.
[0033] According to the conventional art, the operation control is
not performed. Consequently, when the amount of ice in the inner
pipe 12 exceeds a certain amount as the ice packing factor IPF
increases with a lapse of a time, the drive current of the motor 26
sharply increases. Then, when the drive current exceeds a
predetermined value A1, an overcurrent protective device is
operated to stop the operation of the motor 26. In this case, since
the motor 26 continuously operates at a high torque until the
operation of the motor 26 is stopped, the blades 24, the support
bars 23, and the like of the ice scraper 15 are possibly
damaged.
[0034] The operation control according to the first embodiment is
equal to that according to the conventional art in the current
value of the motor 26 until the time t1 at which the amount of ice
in the inner pipe 12 reaches a certain amount. According to the
first embodiment, however, the current value of the motor 26
gradually increases after the time t1. Since the amount of ice is
decreased in such a manner that the value of the evaporation
temperature is set larger than usual in accordance with the
increase in current value as described above, the increase in
current value in the first embodiment is gentler than that in the
conventional art.
[0035] When the current value of the motor 26 exceeds the second
current value, that is, 11 A at the time t2, the thermostat is
forcibly turned off to stop the operation of the ice-making machine
1. With this configuration, since ice is not newly made although
the ice slurry in the seawater tank 9 is used, the amount of ice in
the inner pipe 12 gradually decreases, and the drive current of the
motor 26 also gradually decreases with this decrease. When the
current value of the motor 26 falls below 9 A at a time t3, the
thermostat, which has been forcibly turned off, is turned on again
to restart the operation of the ice-making machine 1. The amount of
ice in the inner pipe 12 increases again after the restart of the
operation of the ice-making machine 1. When the current value of
the motor 26 exceeds 11 A at a time t4, the thermostat is forcibly
turned off again to stop the operation of the ice-making machine
1.
[0036] In the first embodiment, the operation of the ice-making
machine 1 that is an equipment-side element is controlled based on
the current value of the motor 26 of the ice scraper 15 in the
ice-making machine 1. This configuration thus improves the
reliability of operation control on the ice-making machine 1
irrespective of occurrence of, for example, abnormal communications
with an equipment side in the conventional art. This configuration
enables a reduction in risk of damage to the blades 24 and the
support bars 23 of the ice scraper 15 due to ice made excessively,
and improves the reliability of the ice-making system A as a
system.
[0037] In the first embodiment, the evaporation temperature is
increased stepwise in accordance with an excess of the current from
the first current value. This configuration therefore enables
stepwise reduction in amount of ice to be made by the ice-making
machine 1.
Second Embodiment
[0038] In order to control the operation of the ice-making machine
1, a second embodiment focuses attention on an increase in pressure
loss of the seawater flowing through the inner pipe 12 of the
ice-making machine 1 from the inlet toward the outlet with an
increase in amount of ice in the inner pipe 12. According to the
second embodiment, specifically, the evaporation temperature of the
refrigerant to be supplied to the ice-making machine 1 is increased
when a pressure difference between a pressure of the seawater (the
medium to be cooled) at the inlet of the ice-making machine 1 and a
pressure of the seawater at the outlet of the ice-making machine 1
exceeds a first pressure value. In the second embodiment, a
pressure sensor 32 detects a pressure of the seawater at the
seawater inlet pipe 16 of the ice-making machine 1, and a pressure
sensor 33 detects a pressure of the seawater at the seawater outlet
pipe 17 of the ice-making machine 1 (see FIG. 2). The operation of
the ice-making machine 1 is controlled using pressure values which
the pressure sensors 32 and 33 transmit to the control apparatus
30.
[0039] FIG. 6 illustrates exemplary control on an evaporation
temperature in the operation control method according to the second
embodiment. In FIG. 6, the vertical axis indicates a magnification
of the evaporation temperature of the refrigerant in the evaporator
E, that is, a ratio of the evaporation temperature to a normal
evaporation temperature to be described later. In this control
example, the evaporation temperature is set at a normal set
temperature t0 (e.g., -15.degree. C.) during a period that the
pressure difference between the pressure of the seawater at the
seawater inlet pipe 16, the pressure being detected by the pressure
sensor 32, and the pressure of the seawater at the seawater outlet
pipe 17, the pressure being detected by the pressure sensor 33, is
equal to or less than 0.03 MPa. In the second embodiment, when the
pressure difference exceeds a first pressure value, that is, 0.03
MPa, the evaporation temperature of the refrigerant to be supplied
into the evaporator E is increased. More specifically, in the
second embodiment, the evaporation temperature is set higher
stepwise in accordance with an excess of the pressure difference.
For example, when the pressure difference is more than 0.03 MPa,
but is equal to or less than 0.04 MPa, the operation is controlled
to set the evaporation temperature 0.9 times as low as the normal
evaporation temperature t0. In addition, when the pressure
difference is more than 0.04 MPa, but is equal to or less than 0.05
MPa, the operation is controlled to set the evaporation temperature
0.8 times as low as the normal evaporation temperature t0. The
amount of ice is decreased in such a manner that the evaporation
temperature is set higher than the normal value in accordance with
the increase in pressure difference.
[0040] In the second embodiment, when the pressure difference
exceeds a second pressure value larger than the first pressure
value, the thermostat is forcibly turned off to stop the operation
of the ice-making machine 1. In other words, the operation of the
compressor 2 is stopped to stop the circulation of the refrigerant
through the refrigerant circuit. It should be noted that the ice
scraper 15 is continuously operated even when the thermostat is
forcibly turned off. After the thermostat is forcibly turned off,
when the pressure difference decreases to a certain value, for
example, 0.06 MPa, the thermostat, which has been forcibly turned
off, is turned on again to restart the operation of the compressor
2.
[0041] According to the second embodiment, the operation of the
ice-making machine 1 that is an equipment-side element is
controlled based on the pressure difference between the pressure of
the seawater (the medium to be cooled) at the seawater inlet pipe
16 of the ice-making machine 1 and the pressure of the seawater at
the seawater outlet pipe 17 of the ice-making machine 1. This
configuration thus improves the reliability of operation control on
the ice-making machine 1 irrespective of occurrence of, for
example, abnormal communications with an equipment side in the
conventional art. This configuration enables a reduction in risk of
damage to the blades 24 and the support bars 23 of the ice scraper
15 due to ice made excessively, and improves the reliability of the
ice-making system A as a system.
[0042] In the second embodiment, the evaporation temperature is
increased stepwise in accordance with an excess of the pressure
difference from the first pressure value. This configuration
therefore enables stepwise reduction in amount of ice to be made by
the ice-making machine 1.
Other Modifications
[0043] The present disclosure is not limited to the foregoing
embodiments, and various modifications may be made within the
claims.
[0044] For example, in the foregoing embodiment (the first
embodiment), the first current value of the motor and the second
current value larger than the first current value are 6 A and 11 A,
respectively. However, these current values are merely exemplary,
and the present disclosure is not limited thereto. The first
current value and the second current value are selectable as
appropriate based on the size of the ice scraper, the
characteristics of the motor, and others.
[0045] Likewise, in the foregoing embodiment (the second
embodiment), the first pressure value and the second pressure value
larger than the first pressure value are 0.03 MPa and 0.08 MPa,
respectively. However, these pressure values are merely exemplary,
and the present disclosure is not limited thereto. The first
pressure value and the second pressure value are selectable as
appropriate based on the size of the ice scraper, the
characteristics of the pump, and others.
[0046] Moreover, in the foregoing embodiment (the first
embodiment), when the current value of the motor decreases to 9 A,
the thermostat, which has been forcibly turned off, is turned on
again to restart the operation of the compressor. However, the
current value at the time when the thermostat is turned on again is
not limited thereto, and is selectable as appropriate based on the
size of the ice scraper, the characteristics of the motor, and
others.
[0047] Likewise, in the foregoing embodiment (the second
embodiment), when the pressure difference between the pressures at
the inlet and outlet of the ice-making machine decreases to 0.06
MPa, the thermostat, which has been forcibly turned off, is turned
on again to restart the operation of the compressor. However, the
pressure difference at the time when the thermostat is turned on
again is not limited thereto, and is selectable as appropriate
based on the size of the ice scraper, the characteristics of the
pump, and others.
[0048] Moreover, in the foregoing embodiments, the evaporation
temperature is increased stepwise in accordance with an excess of
the current or the pressure difference. The evaporation temperature
may alternatively be increased linearly in accordance with the
excess. Also in the foregoing embodiments, the evaporation
temperature is increased stepwise in accordance with an excess of
the current or the pressure difference. The evaporation temperature
may alternatively be increased by a preset temperature when the
current or the pressure difference exceeds the first current value
or the first pressure value.
[0049] Moreover, in the foregoing embodiment (the second
embodiment), the pressure sensor 32 configured to detect a pressure
of the seawater at the inlet of the ice-making machine 1 is
disposed near the seawater inlet pipe 16. However, the pressure
sensor 32 may be disposed at any location as long as it is capable
of detecting a pressure of the seawater before heat exchange with
the refrigerant in the evaporator E. For example, the pressure
sensor 32 may be disposed at a position S1 indicated by a chain
double-dashed line in FIG. 2 (inside the inner pipe 12). The same
applies to the pressure sensor 33 configured to detect a pressure
of the seawater at the outlet of the ice-making machine 1. The
pressure sensor 33 may be disposed at a position S2 indicated by a
chain double-dashed line in FIG. 2 (inside the inner pipe 12).
[0050] In the foregoing embodiments, the evaporator E is of a
flooded type, in which most of the annular space 14 between the
inner pipe 12 and the outer pipe 13 is filled with the liquid
refrigerant. The evaporator E may alternatively be of a type, in
which the refrigerant is jetted through a nozzle into the annular
space 14 between the inner pipe 12 and the outer pipe 13.
EXPLANATION OF REFERENCES
[0051] 1: ICE-MAKING MACHINE
[0052] 2: COMPRESSOR
[0053] 3: HEAT SOURCE-SIDE HEAT EXCHANGER
[0054] 4: FOUR-WAY SWITCHING VALVE
[0055] 5: UTILIZATION-SIDE EXPANSION VALVE
[0056] 6: HEAT SOURCE-SIDE EXPANSION VALVE
[0057] 7: SUPERHEATER
[0058] 8: RECEIVER
[0059] 9: SEAWATER TANK
[0060] 10: PUMP
[0061] 11: FAN
[0062] 12: INNER PIPE
[0063] 13: OUTER PIPE
[0064] 14: ANNULAR SPACE
[0065] 15: ICE SCRAPER
[0066] 16: SEAWATER INLET PIPE
[0067] 17: SEAWATER OUTLET PIPE
[0068] 18: REFRIGERANT INLET PIPE
[0069] 19: REFRIGERANT OUTLET PIPE
[0070] 20: REFRIGERANT SUPPLY PORT
[0071] 21: REFRIGERANT DISCHARGE PORT
[0072] 22: SHAFT
[0073] 23: SUPPORT BAR
[0074] 24: BLADE
[0075] 25: FLANGE
[0076] 26: MOTOR
[0077] 30: CONTROL APPARATUS
[0078] 31: AMMETER
[0079] 32: PRESSURE SENSOR
[0080] 33: PRESSURE SENSOR
[0081] A: ICE-MAKING SYSTEM
[0082] E: EVAPORATOR
* * * * *