Automatic ice maker using thermoacoustic refrigeration and refrigerator having the same

An automatic ice maker for saving an ice making time. The automatic ice maker has a U-shaped resonator filled up with an inertia gas, a pair of ice trays attached to both ends of the U-shaped resonator in a reverse direction to each other, a pair of speakers attached to both ends of the U-shaped resonator for compressing and expanding parcels of the inertia gas by applying an acoustic pressure to the U-shaped resonator thereby varying a temperature distribution in the U-shaped resonator, a pair of heat exchangers for transferring an inner temperature of the U-shaped resonator to the ice trays, a reversible motor for driving the U-shaped resonator in a forward or a reverse direction at an angle of 180 degrees, and an electric control unit for sequentially operating the speakers and the reversible motor. The automatic ice maker can be adopted to a refrigerator or other refrigeration system. By the automatic ice maker, the ice making time can be saved and the productivity in making the ice increases.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an automatic ice maker, and more 
particularly to an automatic ice maker capable of saving an ice making 
time by using thermoacoustic refrigeration, and a refrigerator having the 
automatic ice maker. 
2. Description of the Prior Art 
Generally, a refrigerator is an apparatus for storing various foods in 
either a frozen or refrigerated condition to keep freshness of the foods 
for a long time. Such a refrigerator includes a compressor which 
circulates a refrigerant by compressing the refrigerant, a condenser for 
condensing the refrigerant to a liquid phase, and an evaporator for 
generating a chilled air by evaporating the liquid phase refrigerant. 
The refrigerator has a freezing chamber for storing frozen foods such as 
meats or an ice cream, and a refrigerating chamber for storing foods at a 
relatively lower temperature. The chilled air generated by the evaporator 
is introduced into the refrigerating and freezing chambers by a fan. 
An ice maker having an ice tray is installed in the freezing chamber for 
making an ice by using the low temperature of the freezing chamber. A 
water supply device feeds water into the ice tray and a driving device 
rotates the ice tray to separate the ice from the ice tray when an ice 
making process has been completed. 
Examples of the ice maker are disclosed in U.S. Pat. No. 5,177,980 (issued 
to Akira Kawamoto, et al.) and U.S. Pat. No. 5,400,605 (issued to Sung-Ki 
Jeong). 
FIG. 1 is a perspective view for showing a conventional automatic ice 
maker. As illustrated in FIG. 1, a driving section (not shown) is disposed 
at a front portion of a freezing chamber, and a fixing member 41 which is 
protruded rearward and has an L-shape is disposed at one end of the rear 
portion of the driving section. In the driving section, a driving 
apparatus having a motor, a gear mechanism and a rotating shaft 20 is 
installed. The driving apparatus reduces the rotation speed of the motor 
by the gear mechanism and transmits the reduced rotational speed to 
rotating shaft 20. 
In fixing member 41, an ice tray 10 is disposed. At the front center 
portion of ice tray 10, a rotating pin 11 is formed. The front center 
portion of rotating pin 11 is connected to and supported by rotating shaft 
20 which receives the rotational force generated by the motor. In 
addition, at the rear portion of ice tray 10, a supporting shaft 13 is 
formed. Ice tray 10 is rotatably fixed to fixing member 41 through 
supporting shaft 13. The rotational force generated by the motor is 
transmitted to rotating shaft 20 through the gear mechanism, and the 
rotational force is transmitted to ice tray 10 through rotating pin 11. 
Accordingly, ice tray 10 can be rotated by the rotation of rotating shaft 
20. 
Ice tray 10 is made of synthetic resin, such as plastic, which can be 
twisted laterally. Ice tray 10 has a hexahedral shape of which the upper 
surface is opened. The inside of ice tray 10 is partitioned into a 
plurality of concave portions to make the ice. The cross-section of the 
side portion of the concave portion has a reverse mesa shape for 
advantageously removing the ice from ice tray 10. Water is supplied into 
ice tray 10 by a water feeding apparatus. 
At the rear portion of ice tray 10, that is, at one edge portion where 
supporting shaft 13 is formed, an ice separating plate 15 is formed along 
the length of ice tray 10. In addition, at one corner portion of fixing 
member 41, that is, at the corner portion opposite to ice separating plate 
15, a stopper 31 is formed. Stopper 31 makes contact with ice separating 
plate 15 to limit the rotation of ice tray 10 when ice tray 10 is rotated 
to separate the ice from ice tray 10. 
At the lower portion of the freezing chamber and below ice tray 10, an ice 
reservoir (not shown) is disposed. The separated ice through the rotation 
of ice tray 10 is stored in the ice reservoir. 
FIG. 2 is a schematic perspective view for explaining the ice separating 
process in the conventional automatic ice maker. 
In the conventional automatic ice maker illustrated in FIG. 1, when the ice 
is obtained in the concave portion of ice tray 10, a microcomputer (not 
shown) senses the ice through a temperature sensor (not shown) provided in 
ice tray 10. When the microcomputer determines that the ice is made in ice 
tray 10, the microcomputer sends an ice separating signal to the motor for 
driving the motor. The rotational force of the motor is transmitted to 
rotating pin 11 through rotating shaft 20 so that ice tray 10 rotates at 
an angle of 180 degrees, as illustrated in FIG. 2. At this time, ice 
separating plate 15 makes contact with stopper 31 for preventing a further 
rotation of ice tray 10. However, the rotational force of the motor is 
still transmitted to ice tray 10 through rotating pin 11. Accordingly, ice 
tray 10 is subjected to a torsional stress, so the ice formed in ice tray 
10 is separated from ice tray 10 and falls down into the ice reservoir. 
However, in the conventional automatic ice maker, the ice making is carried 
out by using the temperature of the freezing chamber, so a relatively long 
time is required for making the ice. If a user wants to rapidly make the 
ice, an energy loss results because the user should raise the temperature 
of the freezing chamber. 
In order to overcome the above problem, a refrigerator having a separate 
ice making chamber in a freezing chamber is suggested. In the above 
refrigerator, a chilled air is guided into the ice making chamber through 
a duct so the ice making chamber has a relatively lower temperature than 
the temperature of the freezing chamber. However, this kind of 
refrigerator may reduce a usable space in the freezing chamber. 
SUMMARY OF THE INVENTION 
The present invention has been made to overcome the above described problem 
of the prior art. Accordingly, it is an object of the present invention to 
provide an automatic ice maker which can save an ice making time by making 
an ice by using a thermoacoustic refrigeration. 
Another object of the present invention is to provide a refrigerator having 
a automatic ice maker which makes an ice by using a thermoacoustic 
refrigeration. 
To accomplish the first object of the present invention, there is provided 
an automatic ice maker comprising: 
a resonator filled up with an inertia gas; 
at least one ice tray attached to the resonator; 
a first means for compressing and expanding parcels of the inertia gas by 
applying an acoustic pressure to the resonator thereby varying a 
temperature distribution in the resonator; 
a second means for transferring an inner temperature of the resonator to 
the ice tray; 
a reversible motor for driving the resonator in a forward or a reverse 
direction at an angle of 180 degrees; and 
an electric control unit for sequentially operating the first means and the 
reversible motor. 
To accomplish the second object of the present invention, there is provided 
a refrigerator comprising: 
a housing having a refrigerating chamber, a freezing chamber, and an 
evaporator chamber which is disposed at a rear portion of the freezing 
chamber; 
an evaporator for generating a chilled air, the evaporator being disposed 
in the evaporator chamber; 
a fan assembly for blowing the chilled air generated by the evaporator into 
the refrigerating and freezing chambers; 
a first means installed in the freezing chamber and filled up with an 
inertia gas; 
at least one ice tray attached to the first means; 
a water supplying device for supplying a water into the ice tray; 
a second means for compressing and expanding parcels of the inertia gas by 
applying an acoustic pressure to the first means; 
a third means for transferring an inner temperature of the first means to 
the ice tray; 
a fourth means for driving the first means in a forward or a reverse 
direction; and 
an electric control unit for sequentially operating the first and fourth 
means. 
According to the preferred embodiment of the present invention, the first 
means includes a U-shaped resonator filled up with a helium gas. The ice 
tray includes first ice tray and second ice tray which are disposed in a 
reverse direction to each other. The first ice tray is positioned on an 
upper surface of the first end of the U-shaped resonator, and the second 
ice tray is positioned on an lower surface of the second end of the 
U-shaped resonator. 
The second means includes a first speaker attached to a front portion of a 
first end of the U-shaped resonator and a second speaker attached to a 
front portion of a second end of the U-shaped resonator. The electric 
control unit sequentially applies an electric signal to the first and 
second speakers with a time interval so that the first and second speakers 
are sequentially operated while maintaining the predetermined time 
interval. 
The third means includes first and second heat exchangers provided in the 
U-shaped resonator. The first heat exchanger is adjacent to the first end 
of the U-shaped resonator and the second heat exchanger is adjacent to the 
second end of the U-shaped resonator. The fourth means includes a 
reversible motor installed in the evaporator chamber. 
The water is supplied from the water supplying device into the first ice 
tray. 
Then, the electric control unit operates the second speaker attached to the 
front portion of the second end of the U-shaped resonator. 
Accordingly, the temperature of parcels of the helium gas adjacent to the 
second speaker is raised by adiabatic compression caused by a standing 
wave radiated from the second speaker, and the temperature of parcels of 
the helium gas remoted from the second speaker is lowered by adiabatic 
expansion. Accordingly, the second end of the U-shaped resonator is heated 
and the first end of the U-shaped resonator is chilled. 
The first heat exchanger transfers the lowered temperature to the first ice 
tray thereby freezing the water filled in the first ice tray. 
When a predetermined time lapses, the electric control unit operates the 
reversible motor so that the U-shaped resonator is rotated at an angle of 
180 degrees by the reversible motor. 
Then, the water is supplied into the second ice tray through the water 
supplying device and the electric control unit operates the first speaker 
attached to the front portion of the first end of the U-shaped resonator. 
Accordingly, the first end of the U-shaped resonator is heated and the 
second end of the U-shaped resonator is chilled. 
At this time, the first heat exchanger transfers the raised temperature to 
the first ice tray having ice cubes therein so that the ice cubes are 
separated from the first ice tray. 
In addition, the second heat exchanger transfers the lowered temperature to 
the second ice tray so the water filled in the second ice tray is frozen. 
The ice maker according to the present invention makes the ice by using the 
thermoacoustic refrigeration so that the ice making time can be saved. 
In addition, the ice maker can rapidly makes the ice without controlling 
the temperature of the evaporator, so the temperature distribution in the 
freezing chamber can be uniformly maintained.

DETAILED DESCRIPTION OF THE INVENTION 
Hereinafter, a preferred embodiment of the present invention will be 
explained in detail with reference to the accompanying drawings. 
FIG. 3 shows a refrigerator 100 having an automatic ice maker 200 according 
to the present invention. The ice maker according to the present invention 
can also be adopted to a freezer or other refrigeration system. 
As shown in FIG. 3, refrigerator 100 comprises a housing 10 having a 
refrigerating chamber 2 and a freezing chamber 1 which is separated from 
refrigerating chamber 2 by a partition wall 3. An evaporator chamber 7, in 
which an evaporator 4 is installed, is formed at a rear portion of 
freezing chamber 1. A compressor 6 is disposed below refrigerating chamber 
2 and a condenser (not shown) is connected between compressor 6 and 
evaporator 4. 
Compressor 6 compresses a refrigerant to a high-pressure and 
high-temperature refrigerant, and the condenser makes a liquid-phase 
refrigerant by discharging a heat from the high-pressure and 
high-temperature refrigerant. The liquid phase refrigerant is supplied to 
and evaporated by evaporator 4, thereby generating a chilled air. In 
addition, a heater 9 is installed below evaporator 4 so as to defrost a 
frost adhering to evaporator 4. 
Installed above evaporator 4 is a fan assembly 5 for blowing an air toward 
freezing chamber 1. In addition, some of the chilled air is introduced 
into refrigerating chamber 2 through a chilled air duct 45 formed at a 
rear portion of evaporator chamber 7 and through a chilled air inlet 42 
which is formed at a rear wall of refrigerating chamber 2. The chilled air 
which has been introduced into freezing and refrigerating chambers 1 and 2 
is re-circulated into evaporator chamber 7 through first and second 
chilled air return passages 43 and 44 which are formed at a lower portion 
of freezing chamber 1 and at an upper portion of refrigerating chamber 2, 
respectively. 
A main part of automatic ice maker 200 (hereinafter, simply referred to as 
ice maker) according to the present invention is installed in freezing 
chamber 1. An ice reservoir 60 is installed below ice maker 200 for 
storing the ice dropping from ice maker 200. Ice maker 200 will be more 
detailedly explained below with reference to FIGS. 4 to 6. 
A water supplying device 50 for supplying water into ice maker 200 is 
disposed on an upper surface of housing 10. Water supplying device 50 
includes a water tank 51 provided on the upper surface of housing 10 and a 
water supplying pipe 52 which is disposed at a lower portion of water tank 
51 and extends into freezing chamber 1 by passing through an upper wall of 
housing 10. Water supplying pipe 52 is provided at a circumference thereof 
with a heating coil 54 for preventing water supplying pipe 52 from 
freezing. 
Referring to FIG. 4, ice maker 200 has a U-shaped resonator 210 filled up 
with an inertia gas, such as helium gas. Though the resonator is 
illustrated as a U-shape, the shape of the resonator can vary according to 
the embodiments. For example, a linearly shaped resonator can be used 
instead of the U-shaped resonator. 
A first ice tray 240 for receiving the water from water supplying device 50 
is positioned on an upper surface of a first end of U-shaped resonator 
210, and a second ice tray 250 is positioned on a lower surface of a 
second end of U-shaped resonator 210. First ice tray 240 is arranged 
corresponding to water supply pipe 52 of water supplying device 50. 
However, if U-shaped resonator 210 rotates at an angle of 180 degrees, 
second ice tray 240 corresponds to water supply pipe 52 of water supplying 
device 50. 
First and second ice trays 240 and 250 are secured to U-shaped resonator 
210 by means of an ultraviolet bond or the like. According to another 
embodiment of the present invention, first and second ice trays 240 and 
250 are detachably secured to U-shaped resonator 210. 
When the ice making process is completed, U-shaped resonator 210 is rotated 
at the angle of 180 degrees by a reversible motor 280 which is installed 
in evaporator chamber 7. Reversible motor 280 is connected to an electric 
control unit 300 so as to be controlled by electric control unit 300. A 
rotating shaft 285 of reversible motor 280 extends into freezing chamber 1 
and is connected to U-shaped resonator 210. Accordingly, U-shaped 
resonator 210 rotates in a driving direction of reversible motor 280. 
Ice maker 200 further has first and second speakers 220 and 230 which apply 
an acoustic pressure to U-shaped resonator 210 thereby compressing and 
expanding parcels of the helium gas contained in U-shaped resonator 210. 
When first or second speaker 220 or 230 operates, a temperature 
distribution in U-shaped resonator 210 varies. That is, the temperature of 
the parcels of the helium gas adjacent to the speaker generating the 
acoustic pressure is raised by adiabatic compression caused by a standing 
wave, and the temperature of the parcels of the helium gas remoted from 
the speaker is lowered by adiabatic expansion. 
First speaker 220 is attached to a front portion of the first end of 
U-shaped resonator 210 and second speaker 230 is attached to a front 
portion of the second end of U-shaped resonator 210. First and second 
speakers 220 and 230 are connected to electric control unit 300. Electric 
control unit 300 sequentially applies an electric signal to first and 
second speakers 220 and 230 with a predetermined time interval so that 
first and second speakers 220 and 230 are sequentially operated while 
maintaining the predetermined time interval. 
That is, when first ice tray 240 is filled up with the water, electric 
control unit 300 operates second speaker 230 thereby freezing the water 
filled in first ice tray 240. Then, after U-shaped resonator 210 rotates 
at the angle of 180 degrees by reversible motor 280, electric control unit 
300 operates first speaker 220 thereby freezing the water filled in second 
ice tray 250. 
On the other hand, first and second heat exchangers 260 and 270 are 
provided in U-shaped resonator 210 for transferring the inner temperature 
of U-shaped resonator 210 to first and second ice trays 240 and 250, 
respectively. 
First heat exchanger 260 is adjacent to the first end of U-shaped resonator 
210 and second heat exchanger 270 is adjacent to the second end of 
U-shaped resonator 210. More preferably, first and second heat exchangers 
260 and 270 are positioned corresponding to first and second ice trays 240 
and 250, respectively. 
Referring to FIG. 5, each heat exchanger has a lattice shape and includes a 
plurality of vertical plates 255 and a plurality of horizontal plates 259 
which are coupled to vertical plates 255. Vertical plates 255 are 
positioned in a row and formed with a plurality of longitudinal slots 257. 
The plurality of horizontal plates 259 are inserted into longitudinal 
slots 257 so that vertical plates 255 are connected to one another. 
As shown in FIG. 6, a distance d between vertical plates 255 is preferably 
1 mm and a distance D between horizontal plates 259 is preferably 1 mm. 
Refrigerator 100 having ice maker 200 according to the present invention 
operates as follows. 
Firstly, the water is supplied from water supplying device 50 into first 
ice tray 240. However, it is also possible for an user to manually supply 
the water into first ice tray 240. When the water is supplied by water 
supplying device 50, a sensor (not shown) detects the amount of the water 
in first ice tray 240 and sends a signal to electric control unit 300 when 
first ice tray 240 is fully filled up with the water. 
Then, electric control unit 300 operates second speaker 230 attached to the 
front portion of the second end of U-shaped resonator 210. 
Accordingly, second speaker 230 applies the acoustic pressure into U-shaped 
resonator 210 thereby compressing and expanding the parcels of the helium 
gas filled in U-shaped resonator 210. 
That is, as detailedly shown in FIG. 6, the temperature of a parcel A of 
the helium gas adjacent to second speaker 230 is raised by adiabatic 
compression caused by a standing wave radiated from second speaker 230, 
and the temperature of a parcel B of the helium gas remoted from second 
speaker 230 is lowered by adiabatic expansion. Accordingly, the second end 
of U-shaped resonator 210 is heated and the first end of U-shaped 
resonator 210 is chilled. 
First heat exchanger 260 disposed in the first end of U-shaped resonator 
210 transfers the lowered temperature to first ice tray 240 thereby 
freezing the water filled in first ice tray 240. 
The temperature of the helium gas is lowered at -290.degree. C. when it is 
subjected to adiabatic expansion so the water filled in first ice tray 240 
is rapidly frozen in a predetermined time. The predetermined time is 
obtained through a plurality of tests and is pre-set in electric control 
unit 300. 
When the predetermined time lapses, electric control unit 300 operates 
reversible motor 280 so that U-shaped resonator 210 is rotated at the 
angle of 180 degrees by reversible motor 280. 
When U-shaped resonator 210 rotates at the angle of 180 degrees, first ice 
tray 240 is replaced with second ice tray 250. That is, second ice tray 
250 moves to a position where it can receive the water from water 
supplying device 50. 
Then, the water is supplied into second ice tray 250 through water 
supplying device 50 and electric control unit 300 operates first speaker 
220 attached to the front portion of the first end of U-shaped resonator 
210. 
Accordingly, the temperature of the parcels of the helium gas adjacent to 
first speaker 220 is raised by adiabatic compression caused by a standing 
wave radiated from first speaker 220, and the temperature of the parcels 
of the helium gas remote from first speaker 220 is lowered by adiabatic 
expansion. Therefore, the first end of U-shaped resonator 210 is heated 
and the second end of U-shaped resonator 210 is chilled. 
At this time, first heat exchanger 260 disposed in the first end of 
U-shaped resonator 210 transfers the raised temperature to first ice tray 
240 having ice cubes therein so that the ice cubes are separated from 
first ice tray 240. The ice cubes are collected in ice reservoir 60 
disposed in a bottom wall of freezing chamber 1. In addition, second heat 
exchanger 270 transfers the lowered temperature to second ice tray 250 so 
the water filled in second ice tray 250 is frozen. 
This process is continuously carried out by sequentially and repeatedly 
applying the electric signal to second speaker 230, reversible motor 280 
and first speaker 220. 
As described above, the ice maker according to the present invention makes 
the ice by using the thermoacoustic refrigeration so that the ice making 
time can be saved. 
In addition, the ice maker can rapidly makes the ice without controlling 
the temperature of the evaporator, so the temperature distribution in the 
freezing chamber can be uniformly maintained. 
Although the preferred embodiment of the invention has been described, it 
is understood that the present invention should not be limited to this 
preferred embodiment, but various changes and modifications can be made by 
one skilled in the art within the spirit and scope of the invention as 
hereinafter claimed.