U.S. patent application number 13/461815 was filed with the patent office on 2012-11-15 for automatic ice maker.
This patent application is currently assigned to NIDEC SERVO CORPORATION. Invention is credited to Eiji KURODA, Kenji SUGAYA, Mariko TANAKA, Kazufumi YAMASHITA, Yoshitaka YOKOI.
Application Number | 20120285187 13/461815 |
Document ID | / |
Family ID | 47140917 |
Filed Date | 2012-11-15 |
United States Patent
Application |
20120285187 |
Kind Code |
A1 |
SUGAYA; Kenji ; et
al. |
November 15, 2012 |
AUTOMATIC ICE MAKER
Abstract
An automatic ice maker installed within a freezing compartment
includes an ice tray arranged to hold water and make ice pieces; an
ice ejecting mechanism arranged to eject the ice pieces made in the
ice tray; an ice releasing heater arranged to melt surfaces of the
ice pieces made in the ice tray; a thermostat arranged to detect a
temperature of the ice tray and to operate at a specified
temperature; and an ice storage amount detecting mechanism arranged
to detect an amount of the ice pieces stored within an ice storage
box. The automatic ice maker further includes a switch mechanism
arranged to stop an operation of the ice releasing heater in
conjunction with an operation of the ice ejecting mechanism.
Inventors: |
SUGAYA; Kenji; (Gumma,
JP) ; KURODA; Eiji; (Gumma, JP) ; TANAKA;
Mariko; (Gumma, JP) ; YOKOI; Yoshitaka;
(Gumma, JP) ; YAMASHITA; Kazufumi; (Gumma,
JP) |
Assignee: |
NIDEC SERVO CORPORATION
Kiryu-shi
JP
|
Family ID: |
47140917 |
Appl. No.: |
13/461815 |
Filed: |
May 2, 2012 |
Current U.S.
Class: |
62/137 |
Current CPC
Class: |
F25C 2700/12 20130101;
F25C 5/08 20130101; F25C 2600/04 20130101; F25C 5/187 20130101 |
Class at
Publication: |
62/137 |
International
Class: |
F25C 1/00 20060101
F25C001/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 12, 2011 |
JP |
2011-107703 |
Jul 23, 2011 |
JP |
2011-161461 |
Claims
1. An automatic ice maker installed within a freezing compartment,
comprising: an ice tray arranged to hold water and make ice pieces;
an ice ejecting mechanism arranged to eject the ice pieces made in
the ice tray; an ice releasing heater arranged to melt surfaces of
the ice pieces made in the ice tray; a thermostat arranged to
detect a temperature of the ice tray and to operate at a specified
temperature; an ice storage amount detecting mechanism arranged to
detect a total amount of the ice pieces stored within an ice
storage box; and a switch mechanism arranged to stop an operation
of the ice releasing heater in conjunction with an operation of the
ice ejecting mechanism.
2. The automatic ice maker of claim 1, wherein the switch mechanism
includes a thermostat deenergizing mechanism arranged to stop the
operation of the heater.
3. The automatic ice maker of claim 2, wherein the switch mechanism
is provided in a serial relationship with the thermostat.
4. The automatic ice maker of claim 2, wherein the switch mechanism
includes a return switch built in the thermostat.
5. The automatic ice maker of claim 1, further comprising: a motor;
and a cam mechanism operated by the motor to actuate the ice
ejecting mechanism and the ice storage amount detecting mechanism;
wherein the switch mechanism is operated by the cam mechanism.
6. An automatic ice maker installed within a freezing compartment,
comprising: an ice tray arranged to hold water and to make ice
pieces; an ice ejecting mechanism arranged to eject the ice pieces
made in the ice tray; an ice releasing heater arranged to melt
surfaces of the ice pieces made in the ice tray; a thermostat
arranged to detect a temperature of the ice tray and to operate at
a specified temperature; an ice storage amount detecting mechanism
arranged to detect a total amount of the ice pieces stored within
an ice storage box; and a switch mechanism arranged to operate the
ice releasing heater in conjunction with an operation of the ice
ejecting mechanism until the surfaces of the ice pieces are
regarded as having been melted.
7. The automatic ice maker of claim 6, wherein the switch mechanism
is provided in a serial relationship with the thermostat and is
configured to switch a current supply path of the heater between a
current supply circuit including the thermostat and a circuit
through which an electric current bypassing the current supply
circuit is supplied to the heater regardless of the operation of
the thermostat.
8. The automatic ice maker of claim 6, further comprising: a motor;
and a cam mechanism operated by the motor to actuate the ice
ejecting mechanism and the ice storage amount detecting mechanism;
wherein the switch mechanism is operated by the cam mechanism.
9. The automatic ice maker of claim 8, wherein the ice ejecting
mechanism includes an ice ejecting lever including ice ejecting
claws arranged to rake out the ice pieces from the ice tray in
conjunction with rotation of the motor; the motor is configured to
start operation when the thermostat is turned on by detecting an
ice making temperature; and the ice ejecting claws of the ice
ejecting lever press against the surfaces of the ice pieces held in
the ice tray until the thermostat is turned off at a specified
temperature after the ice tray is heated by the heater.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an automatic ice maker
installed in a freezing compartment of a household refrigerator or
the like that is arranged to repeatedly perform water supplying,
ice making, and ice ejecting operations pursuant to a specified
sequence.
[0003] 2. Description of the Related Art
[0004] Conventionally, an automatic ice maker in a household
refrigerator is usually configured to supply water from above to an
ice tray arranged in a freezing compartment of the automatic ice
maker, uniformly distribute the supplied water into individual ice
molds of the ice tray, freeze the water into ice pieces by using
ambient cold energy, melt the surfaces of the ice pieces by heating
the ice tray with a heating instrument such as a heater arranged
outside the ice tray, and eject the ice pieces by raking out the
ice pieces with an ice ejector.
[0005] In such a conventional automatic ice maker, the ice making
operation and the ice ejecting operation are realized by
controlling the rotating operation of an ice ejecting lever of the
ice ejector and the energizing/deenergizing of the heater in
conjunction with the switching operation of a thermostat, the
rotation of a motor and the resultant operation of electric contact
points.
[0006] In addition, there is available an electronically-controlled
automatic ice maker in which a temperature can be continuously
detected using a thermistor in place of a temperature-detecting
thermostat. An operation startup temperature can be appropriately
set by use of a program stored in a microcomputer of a control
board built in the automatic ice maker. Various kinds of operations
can be set depending on the temperature change within a
refrigerator.
[0007] In the conventional automatic ice maker, the rotation of the
motor and the energizing/deenergizing of the heater are controlled
pursuant to the thermostat operation temperature. The
off-temperature of the thermostat needs to be set sufficiently high
in view of the in-refrigerator situation, the thermostat error and
the operation irregularity. Accordingly, as for the ice ejecting
operation, the thermostat operation temperature is set equal to or
higher than the temperature at which the surfaces of the ice pieces
are regarded as having been sufficiently melted.
[0008] Since, however, the thermostat operation temperature thus
set heavily affects the temperature within the freezing compartment
and the blowing operation to cool the inside of the refrigerator,
it is necessary to strictly set the thermostat operation
temperature depending on the type of the refrigerator. In the
conventional electronically-operated automatic ice maker, there is
a need to add a control board and a built-in program to the ice
maker. This leads to a complicated configuration, an increased
number of required components, and a corresponding price
increase.
SUMMARY OF THE INVENTION
[0009] Preferred embodiments of the present invention provide an
automatic ice maker arranged to reliably perform an ice ejecting
operation without having to execute control using an electronic
control board in spite of changes in the internal temperature of a
freezing compartment and the influence of a blowing operation.
[0010] In accordance with a first preferred embodiment of the
present invention, an automatic ice maker is installed within a
freezing compartment and includes an ice tray arranged to hold
water and make ice pieces; an ice ejecting mechanism arranged to
eject the ice pieces made in the ice tray; an ice releasing heater
arranged to melt surfaces of the ice pieces made in the ice tray; a
thermostat arranged to detect a temperature of the ice tray and to
operate at a specified temperature; an ice storage amount detecting
mechanism arranged to detect a total amount of the ice pieces
stored within an ice storage box; and a switch mechanism arranged
to stop an operation of the ice releasing heater in conjunction
with an operation of the ice ejecting mechanism.
[0011] Since the automatic ice maker includes the switch mechanism
arranged to stop the operation of the ice releasing heater in
conjunction with the operation of the ice ejecting mechanism, it is
possible to stop the supply of an electric current to the heater
regardless of the operation time point of the thermostat.
Accordingly, there is no need to strictly set the thermostat
operation temperature as is required in conventional automatic ice
makers. It thereby becomes unnecessary to perform a task of
preparing a built-in program required in an
electronically-controlled system.
[0012] In accordance with a second preferred embodiment of the
present invention, an automatic ice maker is installed within a
freezing compartment and includes an ice tray arranged to hold
water and make ice pieces; an ice ejecting mechanism arranged to
eject the ice pieces made in the ice tray; an ice releasing heater
arranged to melt surfaces of the ice pieces made in the ice tray; a
thermostat arranged to detect a temperature of the ice tray and to
operate at a specified temperature; an ice storage amount detecting
mechanism arranged to detect a total amount of the ice pieces
stored within an ice storage box; and a switch mechanism arranged
to operate the ice releasing heater in conjunction with an
operation of the ice ejecting mechanism until the surfaces of the
ice pieces are regarded as having been melted.
[0013] Inasmuch as the automatic ice maker includes the switch
mechanism arranged to continuously operate the ice releasing heater
until the surfaces of the ice pieces are regarded as having been
melted, it is not necessary to set the operation time point of the
thermostat in conformity with the installation environment of the
ice maker as is the case in conventional automatic ice makers. It
becomes unnecessary to perform a task of preparing a built-in
program required in an electronically-controlled system. In a
preferred embodiment of the present invention, the heater is turned
on by detecting the temperature with the thermostat. The heater is
turned off when the operation state of the ice ejecting mechanism
indicates that the surfaces of the ice pieces are regarded as
having been melted. This provides an advantage in that the
turning-off timing of the heater does not depend on the detection
of the thermostat temperature easily affected by the surrounding
environment.
[0014] The above and other elements, features, steps,
characteristics and advantages of the present invention will become
more apparent from the following detailed description of the
preferred embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a perspective view of an automatic ice maker in
accordance with a first preferred embodiment of the present
invention.
[0016] FIG. 2 is an electric wiring connection diagram of the
automatic ice maker shown in FIG. 1.
[0017] FIG. 3 is an operation timing chart of the automatic ice
maker shown in FIG. 1.
[0018] FIG. 4 is an operation flowchart of the automatic ice maker
shown in FIG. 1.
[0019] FIG. 5 is an electric wiring connection diagram of an
automatic ice maker in accordance with a second preferred
embodiment of the present invention.
[0020] FIG. 6 is an operation timing chart of the automatic ice
maker shown in FIG. 5.
[0021] FIG. 7 is an electric wiring connection diagram of an
automatic ice maker in accordance with a third preferred embodiment
of the present invention.
[0022] FIG. 8 is an operation timing chart of the automatic ice
maker shown in FIG. 7.
[0023] FIG. 9 is an electric wiring connection diagram of a
conventional automatic ice maker.
[0024] FIG. 10 is an operation timing chart of the automatic ice
maker shown in FIG. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Preferred Embodiment
[0025] An automatic ice maker in accordance with a first preferred
embodiment of the present invention will now be described with
reference to the accompanying drawings. FIG. 1 is a perspective
view of the automatic ice maker in accordance with the first
preferred embodiment of the present invention. The automatic ice
maker preferably includes an ice tray 1 including a plurality of
ice making molds; an ice ejecting lever 2 arranged as an ice
ejecting mechanism provided with a plurality of ice ejecting claws
arranged to rake out ice pieces held in the ice making molds; a
housing 3 arranged to accommodate a drive motor arranged to
rotationally drive the ice ejecting lever 2, a cam mechanism, and
various kinds of switches; an ice releasing heater arranged on the
bottom surface of the ice tray 1; and a feeler arm 4 serving as an
ice storage amount detector arranged to detect an ice storage
amount of an ice storage tank arranged to store ejected ice pieces.
A cam shaft included in the cam mechanism is rotated by the drive
motor and the ice ejecting lever 2 is connected to the cam
shaft.
[0026] FIG. 2 shows a preferred embodiment of the internal wiring
connection arranged to control the operation of the automatic ice
maker configured as above. A drive motor (M) 12 and a hold switch
(SW) 14 (the normally-open (NO) terminal thereof) are connected to
a power supply of, e.g., AC 115/230 V, through a temperature fuse
10. A heater 16 is connected in parallel to a serial circuit of the
drive motor 12 and the hold switch 14 (the normally-open terminal
thereof). A serial circuit of a water switch 18 and a water valve
20 and a serial circuit of a thermostat 22, a thermostat switch 24,
and a feeler arm switch 26 (the normally-open terminal thereof) are
connected between the normally-closed terminal and the
normally-open terminal of the hold switch 14. The normally-closed
terminal of the feeler arm switch 26 is connected to a common
terminal of the hold switch 14. The water valve 20 is preferably
installed in the refrigerator outside the automatic ice maker.
[0027] A cam is provided in the cam shaft rotated by the drive
motor 12. Depending on the rotational position of the cam, the hold
switch 14, the feeler arm switch 26, and the water switch 18 are
switched and operated. The ice ejecting lever 2 is arranged to be
rotated as the cam shaft rotates. The feeler arm 4 is swung in
conjunction with the rotation of the cam shaft within a specified
rotation angle range. The operations of the respective components
caused by the rotation of the cam are as shown in the timing chart
set forth in FIG. 3.
[0028] In the meantime, FIG. 9 is an electric wiring connection
diagram of a conventional automatic ice maker including a twice
rotation-type of ice ejecting lever. The conventional automatic ice
maker is operated in accordance with the timing chart shown in FIG.
10.
[0029] Description will now be made on the operations of the
conventional automatic ice maker shown in FIG. 9. The thermostat 22
is turned off in a state that water is held in an ice tray. Thus
the drive motor 12 waits for ice making without making any
rotation. In this state, a feeler arm 4 is kept in an ice detecting
position.
[0030] If the water in the ice tray is frozen into ice pieces, the
thermostat 22 detecting the ice making temperature is turned on. In
response, the operation in an ice ejecting mode is started up. An
electric current begins to be supplied to the drive motor 12
through the thermostat 22 and the feeler arm switch 26 (the
normally-open terminal thereof). The cam shaft (not shown)
operatively connected to the drive motor 12 begins to rotate. At
the same time, the heater 16 is energized to heat the ice tray,
thereby accelerating the release of the ice pieces. Immediately
after the cam shaft begins to rotate, the hold switch 14 is
operated (the normally-open terminal of the hold switch 14 is
turned on). Thus, an electric current continues to be supplied to
the drive motor 12 through the hold switch 14.
[0031] Thereafter, the feeler arm 4 is moved under the action of
the cam shaft to a position where the feeler arm 4 does not hinder
the ejection of the ice pieces (a position below the ice tray). The
feeler arm switch 26 is operated by the cam mechanism (the
normally-closed terminal of the feeler arm switch 26 is switched
on).
[0032] Ice ejecting claws of an ice ejecting lever connected to the
cam shaft make contact with the surfaces of the ice pieces and
press the ice pieces in such a direction as to rake out the ice
pieces. This state is maintained until the ice pieces become
movable. If the surfaces of the ice pieces held in the ice tray
begin to be melted by the heat of the heater 16 and if the ice
pieces become movable, the ice ejecting lever pushes the ice pieces
and the cam shaft continues to rotate, whereby the ice ejecting
lever can rake out the ice pieces from the ice tray. Before and
after this position, the normally-open terminal of the feeler arm
switch 26 is switched on under the action of the cam surface of the
cam shaft. The feeler arm 4 is swung into the ice detecting
position (a position similar to the position of the preferred
embodiment of the invention shown in FIG. 1).
[0033] If the cam shaft makes approximately one rotation, the water
switch 18 (the normally-closed terminal thereof) is switched on
under the action of the cam surface for a specified time. Since the
thermostat 22 is kept turned on, no electric current flows through
the water valve 20 to thereby eliminate the possibility that water
will be supplied to the ice tray.
[0034] When the cam shaft is rotated 360 degrees, the hold switch
14 is switched to the normally-closed terminal and consequently
turned off. Since the thermostat 22 is turned on at this time, the
drive motor 12 is continuously supplied with an electric current
through the thermostat 22 and is continuously rotated. Thereafter,
the hold switch 14 is switched to continuously supply an electric
current to the drive motor 12. The feeler arm 4 is swung into the
original position and the normally-closed terminal of the feeler
arm switch 26 is turned on.
[0035] The ice pieces raked out from the ice tray by the rotation
of the cam shaft are discharged by the ice ejecting claws from the
lateral surface of the ice tray and are stored in an ice storage
tank existing below the ice tray. Thereafter, the normally-open
terminal of the feeler arm switch 26 is turned on and the feeler
arm 4 is swung into the ice detecting position. Even after the ice
pieces are completely removed from the ice tray, the thermostat 22
is kept turned on. Accordingly, an electric current continues to be
supplied to the heater 16. The ice tray is heated to a specified
temperature. In response, the thermostat 22 detecting the
temperature of the ice tray is turned off.
[0036] If the cam shaft is further rotated and if the
normally-closed terminal of the water switch 18 is turned on, an
electric current begins to be supplied to the water valve 20. This
is because the thermostat 22 is kept turned off. The water valve 20
is opened for a specified time and, therefore, water is supplied to
the ice tray.
[0037] If the supply of water is completed, the water switch 18 is
switched to the normally-open terminal. Just thereafter, the hold
switch 14 is switched to the normally-closed terminal and
consequently turned off. The rotation of the drive motor 12 is
stopped. Thus, the automatic ice maker comes into a standby state
again.
[0038] In the conventional automatic ice maker, as described above,
the ice ejecting mode and the water supplying mode are performed by
rotating the cam shaft twice with the drive motor 12. With such
conventional configuration, the thermostat 22 is turned on
immediately after the ice pieces are made, and then the ice tray is
heated by the heat of the heater 16. The ice pieces are raked out
with the ice ejecting lever 2. The ice tray is further heated to a
specified temperature. The heater 16 is continuously supplied with
an electric current until the thermostat 22 is switched off.
[0039] In this configuration, it may be sometimes the case that,
due to an in-refrigerator situation, thermostat error, or operation
irregularity, the thermostat 22 will not be turned off even when
the ice ejecting lever is rotated to a specified angle. In this
case, the ice tray is continuously heated even after the ice pieces
are released. Thus, electric power will be unnecessarily
consumed.
[0040] In accordance with the present preferred embodiment shown in
FIGS. 2 and 3, the thermostat switch 24, which is preferably a
normally-closed switch of a heater de-energizing switch mechanism,
is arranged between the thermostat 22 and the feeler arm switch 26.
This makes it possible to perform the ice ejecting mode and the
water supplying mode by one rotation of the cam shaft. In addition,
it is possible to reliably perform the ice releasing operation
while minimizing the supply of an electric current to the heater
16.
[0041] Specifically, referring to a flowchart shown in FIG. 4,
water is supplied to the ice tray 1. Thereafter, the ice tray 1 is
cooled to a specified temperature to start ice making. If a
specified time is lapsed and if it is determined that the ice
making is finished, the thermostat 22 is turned on and a closed
circuit is defined by the normally-closed thermostat switch 24 and
so forth. Thus, the drive motor 12 is rotated and the supply of an
electric current to the heater 16 is started. Subsequently, the ice
ejecting claws of the ice ejecting lever 2 connected to the cam
shaft make contact with the surfaces of the ice pieces and press
the ice pieces in such a direction so as to rake out the ice
pieces. This state is maintained until the ice pieces become
movable.
[0042] If the surfaces of the ice pieces held in the ice tray 1
begin to be melted by the heat of the heater 16 and if the ice
pieces become movable, the ice ejecting lever 2 pushes the ice
pieces and the cam shaft continues to rotate. After the ice
ejecting lever 2 is rotated by a specified angle, e.g., about 90
degrees, the thermostat switch 24 is opened by a cam mechanism (not
shown), thereby cutting off the current supply circuit of the
heater 16. This stops the supply of an electric current to the
heater 16. However, the drive motor 12 continues to rotate because
an electric current is continuously supplied to the drive motor 12
through the hold switch 14.
[0043] The temperature of the ice tray 1 is continuously increased
by the residual heat of the heater 16. After the temperature of the
ice tray 1 reaches a predetermined level, the thermostat 22 is
turned off and the connection thereof is cut off. The drive motor
12 continues to rotate thereafter. When the ice ejecting lever 2
reaches a specified position immediately ahead of the starting
point, the water switch 18 is turned on and the connection to the
water valve 20 is performed, thereby transmitting a water supply
signal to the water valve 20. In response, an electric current to
the water valve 20 is supplied for a specified time so that water
is supplied to the ice tray 1. Thereafter, the water switch 18 is
turned off again and the ice ejecting lever 2 is returned back to
the starting point after making one rotation from the ice ejection
startup time. In this manner, a series of operations comes to an
end. The automatic ice maker stops its operation and waits in a
standby state.
Second Preferred Embodiment
[0044] FIGS. 5 and 6 show an automatic ice maker in accordance with
a second preferred embodiment of the present invention. FIG. 5 is a
wiring connecting diagram of the automatic ice maker and FIG. 6 is
a timing chart illustrating the operations of the automatic ice
maker. In the present preferred embodiment, instead of including
the heater deenergizing switch mechanism (the thermostat switch),
the thermostat 22' preferably includes a function of arbitrarily
releasing a contact point.
[0045] If the ice making operation is finished and if the
thermostat 22' is turned on, the supply of an electric current to
the drive motor 12 and the heater 16 is started to perform an ice
ejecting mode. When the ice ejecting lever 2 is rotated by, e.g.,
about 90 degrees, a return switch of the thermostat 22' is operated
by a cam mechanism and the thermostat 22' is forcibly turned off.
Accordingly, it is possible for the cam mechanism to simultaneously
perform the deenergizing of the thermostat 22' and the deenergizing
of the heater 16.
Third Preferred Embodiment
[0046] FIG. 7 shows the internal wiring connection arranged to
control operation in an automatic ice maker in accordance with a
third preferred embodiment of the present invention. A drive motor
12 and a hold switch 14 (the normally-open terminal thereof) are
connected to a power supply of, e.g., AC 115/230 V, through a
temperature fuse 10. A serial circuit of a heater 16 and a heater
switch 28 (the normally-open terminal thereof) is connected in
parallel to the drive motor 12 and the hold switch 14 (the
normally-closed terminal thereof). A serial circuit of a water
switch 18 and a water valve 20 and a serial circuit of a thermostat
22 and a feeler arm switch 26 (the normally-open terminal thereof)
are connected between the normally-closed terminal and the
normally-open terminal of the hold switch 14. The normally-closed
terminal of the feeler arm switch 26 is connected to a common
terminal of the hold switch 14. The normally-closed terminal of the
heater switch 28 is connected to the normally-open terminal of the
hold switch 14.
[0047] A cam is provided in the cam shaft rotated by the drive
motor 12. Depending on the rotational position of the cam, the
heater switch 28, the hold switch 14, the feeler arm switch 26, and
the water switch 18 are switched and operated. The ice ejecting
lever 2 is rotated as the cam shaft rotates. The feeler arm 4 is
swung in conjunction with the rotation of the cam shaft within a
specified rotation angle range. The operations of the respective
components caused by the rotation of the cam are as shown in the
timing chart set forth in FIG. 8.
[0048] The operations of the automatic ice maker of the present
preferred embodiment will now be described with reference to FIGS.
7 and 8. After water is supplied to the ice tray 1, the ice tray 1
is cooled to a specified temperature to start ice making. If a
specified time has lapsed and if the ice making is finished, the
thermostat 22 detecting the ice making temperature is turned on.
Thus, a closed circuit including the drive motor 12 is defined
through the feeler arm switch 26 whose normally-open terminal is
turned on, whereby the drive motor 12 starts a rotating
operation.
[0049] Simultaneously with the start of the rotation operation of
the drive motor 12 and in response to the turning-on of the
thermostat 22, the supply of an electric current to the heater 16
is initiated through the heater switch 28 whose normally-open
terminal is turned on. Thus the ice tray 1 is heated. The cam shaft
is rotated in conjunction with the rotation of the drive motor 12.
Under the action of the cam provided in the cam shaft, the hold
switch 14 is switched from the normally-closed terminal to the
normally-open terminal, so that the drive motor 12 is continuously
supplied with an electric current.
[0050] Thereafter, the heater switch 28 is switched to the
normally-closed terminal to be turned on under the action of the
cam, so that the heater 16 is forcibly supplied with an electric
current. Accordingly, the ice tray 1 is heated. The operation of
turning on the normally-closed terminal of the heater switch 28 is
set to be performed at the timing earlier than the timing at which
the thermostat 22 is turned off by the detection of a predetermined
ice-releasing temperature. Accordingly, even if the thermostat 22
is turned off next time, the drive motor 12 is continuously
supplied with an electric current by the hold switch 14 and is
continuously operated. The heater 16 is continuously supplied with
an electric current through the normally-closed terminal side
current flow path of the heater switch 28. Thus the ice tray 1 is
continuously heated.
[0051] Thereafter, the ice ejecting claws of the ice ejecting lever
2 connected to the cam shaft make contact with the surfaces of the
ice pieces held in the ice tray 1 and press the ice pieces in such
a direction as to rake out the ice pieces. The ice ejecting claws
continue to press the ice pieces until the surfaces of the ice
pieces are melted and the ice pieces become movable. The drive
motor 12 is kept stopped.
[0052] The temperature of the ice tray 1 is continuously increased
by the heat of the heater 16. If the temperature of the ice tray 1
reaches a specified level, the thermostat 22 is turned off.
[0053] In this regard, the operating temperature of the thermostat
22 is set equal to an ice making temperature and an ice releasing
temperature in the ice tray 1. In reality, the operating
temperature of the thermostat 22 is largely affected by the error
and operation irregularity of the thermostat 22 and the cold air
circulation cycle and the blowing method used to cool the freezing
compartment of a refrigerator mounted with this kind of automatic
ice maker. During the cycle of accelerating the cold air
circulation within the freezing compartment, it is sometimes
difficult to release the ice pieces even when the temperature of
the ice tray 1 reaches the specified temperature.
[0054] For that reason, the temperature at which the thermostat 22
is turned off is merely set equal to, e.g., the ice-releasable dish
temperature. The rotation angle of the ice ejecting lever 2 at
which the ice pieces are regarded as having been completely
released is set. The operation time point at which the heater
switch 28 is operated by the cam is set such that the heater switch
28 serving as a switch mechanism is switched over at the rotation
angle.
[0055] As shown in FIG. 8, the supply of an electric current to the
heater 16 is continuously performed even after the thermostat 22 is
turned off. If the surfaces of the ice pieces held in the ice tray
1 begin to be melted, the ice pieces pressed by the ice ejecting
claws of the ice ejecting lever 2 start to move. Thus, the cam
shaft is allowed to rotate and the drive motor 12 is rotated
subsequently. If the ice ejecting lever 2 is rotated into the
rotation angle at which the ice pieces are regarded as having been
completely released, the heater switch 28 is switched to the
normally-open terminal by the cam of the cam shaft, thereby
defining a closed circuit including the thermostat 22. Since the
thermostat 22 is kept turned off at this time, the supply of an
electric current to the heater 16 is stopped.
[0056] If the state in which the ice pieces are regarded as having
been completely released becomes available as set forth above, the
ice pieces are raked out from the ice tray 1 by the ice ejecting
claws of the ice ejecting lever 2 pressing the ice pieces in a
raking-out direction. The ice pieces are discharged from the
lateral surface of the ice tray 1 and are stored in an ice storage
tank arranged below the ice tray 1. Thereafter, the feeler arm
switch 26 is switched to the normally-closed terminal and the
feeler arm 4 is swung into the ice detecting position.
[0057] If the ice ejecting mode is finished in this manner, the
water switch 18 is turned on by the operation of the cam. An
electric current is supplied to the water valve 20 through the
heater 16, the heater switch 28, and the water switch 18. The water
valve 20 is opened for a specified time to supply water to the ice
tray 1. Then, the water valve 20 is closed again. Subsequently, the
ice ejecting lever 2 is returned back to the starting point after
making one rotation. In this manner, a series of operations comes
to an end. The automatic ice maker then waits in a standby
state.
[0058] In the third preferred embodiment described above, the
heater switch 28 is switched from the normally-closed terminal to
the normally-open terminal at the timing when the ice ejecting
lever 2 is rotated into the rotation angle at which the ice pieces
are regarded as having been completely released. The electric
current is continuously supplied to the heater 16 until the
surfaces of the ice pieces are melted. This makes it possible to
reliably perform the ice ejecting operation with the surfaces of
the ice pieces kept in a melted state, without having to strictly
set the operation temperature of the thermostat 22. Accordingly, it
is possible to provide an effect of simplifying the setting of the
thermostat 22 and the manufacture of the automatic ice maker.
[0059] Depending on the load state in the freezing compartment
within which the automatic ice maker is installed, it is sometimes
the case that the temperature of the ice tray 1 fails to reach the
ice-releasable temperature even though the ice pieces are
completely released by forcibly operating the heater 16 through the
heater switch 28. In this case, the supply of an electric current
to the heater 16 is controlled by the operation of the thermostat
22.
[0060] Specifically, as indicated by single-dot chain lines in FIG.
8, the supply of an electric current to the heater 16 is
continuously performed through the thermostat 22 and the feeler arm
switch 26 even when the heater switch 28 is switched to the
normally-open terminal and turned on. This is because the
thermostat 22 is kept turned on. Thereafter, if the temperature of
the ice tray 1 is increased to a specified temperature by the
heater 16, the thermostat 22 is turned off and the supply of an
electric current to the heater 16 is terminated.
[0061] As shown in FIG. 8, the thermostat 22 is turned off after
the heater switch 28 is switched from the normally-open terminal to
the normally-closed terminal. Basically, the switching-off
temperature of the thermostat 22 is set as low as possible (e.g.,
equal to or lower than about 0.degree. C., i.e., an ice melting
point). The heater 16 is configured to be turned off depending on
the rotation angle of the ice ejecting lever 2. The timing at which
the heater switch 28 is switched from the normally-closed terminal
to the normally-open terminal is set in advance depending on the
rotation angle of the ice ejecting lever 2 to an appropriate timing
until the water supplying mode.
[0062] While preferred embodiments of the present invention have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present invention. The
scope of the present invention, therefore, is to be determined
solely by the following claims.
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