Abstrict An air curtain generator generates an air curtain in a refrigerant
compartment of a refrigerator. In the air curtain generator, a sensor
senses open and closed states of a refrigerant compartment door.
A brushless direct current air curtain fan blows cool air into a
refrigerant compartment according to a sensing result of the sensor
in order to generate an air curtain in the refrigerant compartment.
A direct current power source supplies a direct current driving
current to the brushless direct current air curtain fan. A driver
drives the brushless direct current air curtain fan. A microcomputer
controls an operation of the driver according to the sensing result
of the sensor. The air curtain generator maximizes functions of
an air curtain generator by applying a brushless direct current
air curtain fan having low noise level, low power consumption, and
high efficiency thereto. The air curtain generator also controls
a rotating speed of a brushless direct current air curtain fan according
to a state of the refrigerant compartment to thereby adjust air
speed.
Claims What is claimed is:
1. An air curtain generator for a refrigerator, said generator
comprising:
a sensor for sensing open and closed states of a refrigerant compartment
door;
a brushless direct current air curtain fan for blowing cool air
into a refrigerant compartment according to a sensing result of
the sensor in order to generate an air curtain in the refrigerant
compartment;
a direct current power source for supplying a direct current driving
current to the brushless direct current air curtain fan;
a driver for driving the brushless direct current air curtain fan;
and
a microcomputer for controlling an operation of the driver according
to the sensing result of the sensor, wherein the sensor includes
a switch coupled with an alternating current power source, the switch
being open or closed according to the open or closed state of the
refrigerant compartment door for switching voltage supply from the
alternating current power source; a photo coupler for emitting light
responsive to voltage applied thereto from the alternating current
power source through the switch; and an output device for sensing
the open or closed state of the refrigerant compartment door based
on the light emitted by the photo coupler and a direct current voltage
from a direct current power source and outputting a sensing result
signal.
2. An air curtain generator for a refrigerator, said generator
comprising:
a brushless direct current air curtain fan for blowing cool air
into a refrigerant compartment in order to generate an air curtain
in the refrigerant compartment;
a driver for driving the brushless direct current air curtain fan;
a microcomputer for controlling an operation of the driver, and
for judging a state of the refrigerant compartment and generating
a pulse width modulation signal having different pulse widths according
to the judgement result; and
a variable voltage generator for generating a voltage for controlling
a rotating speed of the brushless direct current air curtain fan
which is variable according the pulse widths of the pulse width
modulation signal from the microcomputer.
3. The air curtain generator as set forth in claim 2, wherein when
the refrigerant compartment door is opened or a refrigeration is
performed at high speed, when an open refrigerant compartment door
is closed, and an normal operation of a refrigerator is carried
out, the microcomputer outputs first, second, and third pulse width
modulation signals having first, second, and third pulse widths,
respectively.
4. The air curtain generator as set forth in claim 2, wherein when
the refrigerant compartment door is opened or a refrigeration is
performed at high speed, when an open refrigerant compartment door
is closed, and a normal operation of a refrigerator is carried out,
rotating the brushless direct current air curtain fan at low, middle,
and high speeds, respectively.
5. The air curtain generator as set forth in claim 4, wherein when
the refrigerant compartment door is opened, when the open refrigerant
compartment door is closed, and the normal operation of a refrigerator
is carried out, turning on the brushless direct current air curtain
fan for seventy seconds, at middle speed for ten seconds, and for
thirty seconds per one hour at middle high speed, respectively. Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a refrigerator, and more particularly,
to an air curtain generator for generating air curtain in a refrigerant
compartment of a refrigerator.
2. Prior Art
An air curtain generator is a device which blows cool air generated
by an evaporator of a refrigerator into a refrigerant or freezing
compartment to generate an air curtain in the refrigerant or freezing
compartment.
U.S. Pat. No. 5,765,388, (issued to Yong-Deok Jeon on Jul. 16,
1998) discloses a refrigerator with air curtain generating device
for selectively generating an air curtain in a freezing compartment
or a refrigerant compartment when a freezing compartment door or
a fresh food compartment door is opened.
FIG. 1 shows a conventional air curtain generator 10 of a refrigerator
by using an alternating current(AC) air curtain fan. The air curtain
generator 10 of a refrigerator 10 includes a microcomputer 102,
a driver 104, a relay 106, an AC power source 108, and an AC air
curtain fan 110. The microcomputer 102 senses open and closes states
of a refrigerant compartment door and generates a sensing result
signal according to the sensing result. The sensing result signal
from the microcomputer 102 is applied to the driver 104. The driver
104 outputs a relay on/off signal in response to the sensing result
signal from the microcomputer 102. The relay 106 turns on or off
in response to the relay on/off signal from the driver 104. The
AC power source 110 supplies an AC driving current to the AC air
curtain fan 110. When the relay 106 is in a turn-on state, the AC
air curtain fan 110 rotates and generates and provides an air curtain
into a refrigerant compartment. When a refrigerant compartment door
is opened, in order to prevent cool air from flowing an outside
or to prevent external air from flowing inside of the refrigerator,
the AC air curtain fan 110 disposed at a rear side of the refrigerant
compartment operates to generate and provide an air curtain into
a refrigerant compartment.
Since a conventional air curtain generator for a refrigerator by
using an AC air curtain fan has a high noise level, high power consumption,
and low efficiency, performance of air curtain operation declines.
SUMMARY OF THE INVENTION
Therefore, it is a first object of the present invention, for the
purpose of solving the above mentioned problems, to provide an air
curtain generator for a refrigerator by using a BLDC air curtain
fan having a low noise level, low power consumption, and high efficiency.
It is a second object of the present invention to provide an air
curtain generator for a refrigerator capable of controlling a rotating
speed of a BLDC air curtain fan according to a state of a refrigerant
compartment.
In order to attain the first object, according to the present invention,
there is provided an air curtain generator for a refrigerator, said
generator comprising:
a sensor for sensing open and closed states of a refrigerant compartment
door;
a brushless direct current air curtain fan for blowing cool air
into a refrigerant compartment according to a sensing result of
the sensor in order to generate an air curtain in the refrigerant
compartment;
a direct current power source for supplying a direct current driving
current to the brushless direct current air curtain fan;
a driver for driving the brushless direct current air curtain fan;
and
a microcomputer for controlling an operation of the driver according
to the sensing result of the sensor.
In order to attain the first object, according to the present invention,
there is also provided an air curtain generator for a refrigerator,
said generator comprising:
a brushless direct current air curtain fan for blowing cool air
into a refrigerant compartment in order to generate an air curtain
in the refrigerant compartment;
a driver for driving the brushless direct current air curtain fan;
a microcomputer for controlling an operation of the driver, and
for judging a state of the refrigerant compartment and generating
a pulse width modulation signal having different pulse widths according
to the judgement result; and
a variable voltage generator for generating a voltage for controlling
a rotating speed of the brushless direct current air curtain fan
which is variable according the pulse widths of the pulse width
modulation signal from the microcomputer.
The present invention maximizes functions of an air curtain generator
by applying a BLDC air curtain fan having low noise level, low power
consumption, and high efficiency thereto. The present invention
controls a rotating speed of a BLDC air curtain fan according to
a state of the refrigerant compartment to thereby adjust air speed.
Other objects and further features of the present invention will
become apparent from the detailed description when read in conjunction
with the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become
more apparent from the following description taken in connection
with the accompanying drawings, wherein:
FIG. 1 is a block diagram for showing a conventional air curtain
generator of a refrigerator by using an alternating current air
curtain fan;
FIG. 2 is a side end view for showing a refrigerator having an
air curtain generator according to the present invention;
FIG. 3 is a block diagram for showing a configuration of an air
curtain generator for a refrigerator according to a first embodiment
of the present invention;
FIG. 4 is an enlarged perspective view of the brushless direct
current air curtain fan;
FIG. 5A is a front view of the brushless direct current (BLDC)
motor shown in FIG. 4;
FIG. 5B is a side view of the BLDC motor shown in FIG. 5A;
FIG. 6 is a circuitry diagram for showing a configuration of the
printed circuit board(PCB) shown in FIG. 5B;
FIG. 7 is a truth table which illustrates an operation of the PCB
shown in FIG. 6;
FIG. 8 is a block diagram for showing a configuration of an air
curtain generator for a refrigerator according to a second embodiment
of the present invention; and
FIGS. 9A to 9C are waveforms for showing pulse width modulation
signals generated by a microcomputer shown in FIG. 8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of the present invention will hereinafter
be described in detail with reference to the accompanying drawings.
FIG. 2 shows a refrigerator having an air curtain generator 20
according to the present invention. A circulating duct 116 is defined
along a lower surface of a distribution plate 114 at an upper portion
of a refrigerant compartment 112. An air curtain generator 20 is
mounted at the rear of the circulating duct 116. When a refrigerant
compartment door 118 is opened, the air curtain generator 20 operates
supplies cool air generated by an evaporator 122 to the refrigerant
compartment 112 through a cool air discharge port 120 to thereby
produce an air curtain therein.
Embodiment 1
FIG. 3 shows a configuration of an air curtain generator for a
refrigerator according to a first embodiment of the present invention.
The air curtain generator 20 for a refrigerator includes a sensor
302, a brushless direct current(BLDC) air curtain fan 304, a direct
current(DC) power source 306, a driver 308, and a microcomputer
310.
The sensor 302 senses open and closed states of a refrigerant compartment
door 118. The sensor 302 includes a switch S/W, a photo coupler
302a, and an output device 302b.
The switch S/W is coupled with an alternating current(AC) power
source 300. The switch S/W is open or closed according to the open
or closed state of the refrigerant compartment door 118 and switches
voltage supply from the AC power source 300. When the refrigerant
compartment door 118 is opened, the switch S/W turns on so that
voltage from the AC power source 320 is supplied to the photo coupler
302a. On the contrary, when the refrigerant compartment door 118
is closed, the switch S/W turns off so that voltage from the AC
power source 320 is not supplied to the photo coupler 302a.
The photo coupler 302a emits light responsive to voltage applied
thereto from the AC power source 300 through the switch S/W. The
photo coupler 302a includes a light emitting diode D1 and a phototransistor
Q1. When the switch S/W turns off, the light emitting diode D1 becomes
conductive and emits light. The phototransistor Q1 receives the
light emitted by the light emitting diode D1.
The output device 302b senses the open or closed state of the refrigerant
compartment door 118 based on the light emitted by the photo coupler
302a and a direct current(DC) voltage +5V from a direct current(DC)
power source 312 and outputs a sensing result signal. The output
device 302b includes a resistor R1 having one terminal connected
to the DC power source 312 and the other terminal connected to the
collector of the phototransistor Q1. The output device 302b includes
a resistor R2 having one terminal connected to a junction of the
resistor R1 and the collector of the phototransistor Q1 and the
other terminal connected to the microcomputer 310. The output device
302b includes a capacitor C1 having one terminal connected to a
junction of the resistor R2 and microcomputer 310 and the other
terminal connected to a ground.
When the switch S/W is in a turn-off state for a predetermined
time, that is, when the refrigerant compartment door 118 is open
for a predetermined time, both the light emitting diode D1 and phototransistor
Q1 are turned off, and the DC current voltage +5V from the DC power
source 312 is applied to the output device 302b so that the sensing
result signal of the output device 302b becomes a high level. On
the contrary, when the switch S/W is in a turn-on state, that is,
when the refrigerant compartment door 118 is closed, the photo coupler
302a outputs a high/low signal between 60 to 120 times for 10 seconds
to the output device 302b so that the sensing result signal of the
output device 302b is in a high state for 10 seconds and is in a
low state thereafter.
The brushless direct current air curtain fan 304 blows cool air
into a refrigerant compartment 112 according to a sensing result
of the sensor in order to generate an air curtain in the refrigerant
compartment 112. FIG. 4 is an enlarged perspective view of the BLDC
air curtain fan 304. The BLDC air curtain fan 304 includes a cross
flow fan blades 402 and a BLDC motor 404. The cross flow fan blades
402 blows cool air generated by an evaporator into the refrigerant
compartment 112. The BLDC motor 404 is connected to the cross flow
fan blades 402 and rotates the cross flow fan blades 402.
FIG. 5A is a front view of the brushless direct current (BLDC)
motor shown in FIG. 4 and FIG. 5B is a side view of the BLDC motor
shown in FIG. 5A.
The BLDC motor 404 includes a shaft 502. A ball bearing 504 surrounds
and supports the shaft 502. First and second brackets 511 and 512
adjust the location of the ball bearing 504. A magnet rotor 506
is rotably mounted to an outer side of the ball bearing 504 and
has a magnetic north pole N and a magnetic south pole S.
FIG. 6 is a circuitry diagram for showing a configuration of the
printed circuit board(PCB) 514 shown in FIG. 5B
The PCB 514 includes a Hall sensor 410 and a current generator
602. The Hall sensor 410 senses a location of the magnetic rotor
506 and outputs a location sensing signal. The current generator
602 generates a driving current for controlling a rotation of the
magnetic rotor 506 in response to the location sensing signal from
the Hall sensor 510. The current generator 602 includes first driving
coils 602a and 602b and first and second power transistors 602c
and 602d. The first driving coils 602a and 602b are each connected
to a power supply Vs. The first driving coils 602a and 602b are
connected to each other in parallel and control the rotation of
the magnetic rotor 506.
The first power transistor 602c provides a first coil current .sub.1
to the first coil 602a in response to the location sensing signal
from the Hall sensor 510. The first power transistor 602c includes
an emitter connected to a ground, a base for receiving the location
sensing signal from the Hall sensor 510, and a collector connected
to the first driving coil 602a. The second power transistor 602d
provides a second coil current .sub.2 to the second coil 602b in
response to the first coil current .sub.1 from the first power transistor
602c. The second power transistor 602d includes an emitter connected
to a ground, a base connected to a junction of a first driving coil
602a and the collector of the first power transistor 602c for receiving
the first coil current .sub.1, and a collector connected to the
second driving coil 602b. In FIG. 6, R61 and R62 are resistors for
removing noise. C61 and C62 are capacitors for removing noise. D61
is a diode.
The DC power source 306 supplies a direct current driving current
to the BLDC current air curtain fan 304. The driver 308 drives the
BLDC current air curtain fan 304. The driver 308 includes an npn
transistor Q2 having an emitter connected to a ground, a base for
receiving a control signal from a microcomputer which will be described
later, and a collector connected to the BLDC current air curtain
fan 304. The npn transistor Q2 includes a base resistor R3 and a
resistor R4 which is connected between the base and collector thereof.
The microcomputer 310 controls an operation of the driver 208 according
to the sensing result of the sensor 302. In FIG. 3, R5 and R6 are
resistors which adjust a current from the AC power source 314 to
a rated current flowing through the photo coupler 202a. D2 is a
diode to prevent the light emitting diode D1 from biasing in reverse.
Hereinafter, an operation of the air curtain generator 30 according
to a first embodiment of the present invention will be explained.
When a refrigerant compartment door 118 is opened, the switch S/W
is turned off so that the voltage from the AC power source 300 is
not supplied to the photo coupler 302a. Accordingly, the light emitting
diode D1 and phototransistor Q1 are turned off and the DC voltage
+5V from the DC power source 312 is applied to the output device
302b so that the sensing result signal of the output device 302b
is a high level. The sensing result signal of the output device
302b of a high level is provided to the microcomputer 310.
The microcomputer 310 outputs a driving control signal of a high
level in response to the sensing result signal of a high level from
the output device 302b to the base of the npn transistor Q2 of the
driver 208 through the base resistor R3.
The npn transistor Q2 turns on and drives the BLDC air curtain
fan 304. At this time, the DC power source 306 supplies a DC driving
current to the BLDC air curtain fan 304. Accordingly, the cross
flow fan blades 402 of the BLDC air curtain fan 304 operate and
blow cool air generated by the evaporator 122 into the refrigerant
compartment 112 to produce air curtain therein. The air curtain
excludes external air and prevent cool air in the refrigerator from
discharging outside. The BLDC motor 404 rotates the cross flow fan
blades 402.
An operation of the BLDC air curtain fan 404 will now be described
referring to FIG. 5A to FIG. 6.
When the magnetic rotor 506 is in the position shown in FIG. 6,
the Hall sensor 510 is extremely adjacent to a magnetic pole of
the magnetic rotor 506 and gets the greatest flux.
The Hall sensor 510 senses a magnetic north N pole, sends a driving
signal to the first power transistor 602a to thereby output a big
Hall output voltage V.sub.H+, and causes the first power transistor
602a to become conductive to thereby flow a first coil current .sub.1
so that the first driving coil 602c becomes an excited state.
When the first coil current .sub.1 flows, the magnetic north pole
is generated on the first driving coil 604 according to Fleming's
left-hand rule and the Hall sensor 510 pulls the south pole of the
magnetic rotor 506. When the magnetic north pole of the magnetic
rotor 506 is far from the Hall sensor 410 by a rotation thereof,
the flux which passes through the Hall sensor 510 get lost and a
Hall output voltage(V.sub.H+, V.sub.H-) is not generated in either
case. Accordingly, first and second power transistors 602a and 602b
turns off at the same time.
Although the first driving coil 604 transforms to a nonexcited
state, the magnetic rotor 510 continuously rotates due to the inertia
thereof and moves from the magnetic south pole to the magnetic north
pole by 180.degree. . At this time, the Hall sensor 510 receives
a flux of the magnetic south pole and the second power transistor
602b. Accordingly, the second coil current .sub.2 flows so that
the second driving coil 602d becomes an excited state to thereby
generate a magnetic south pole. The generated magnetic south pole
pulls a magnetic north pole of the magnetic rotor 406 to generate
a rotating force. The operation as mentioned above repeats and a
continuous rotation operation continues. FIG. 7 is a truth table
which illustrates an operation of the PCB 514.
When the refrigerant compartment door 118 is closed, the switch
S/W is turned on so that the voltage from the AC power source 300
is supplied to the photo coupler 202a. Accordingly, the light emitting
diode D1 becomes conductive to emit light. The phototransistor Q1
receives the light emitted by the light emitting diode D1. That
is, the photo coupler 302a outputs a high/low signal between 60
to 120 times for 10 seconds to the output device 302b. Accordingly,
the output device 302b outputs the sensing result signal of a high
state for 10 seconds to the microcomputer 310 in response to the
output signal of the photo coupler 302a.
The microcomputer 310 outputs a driving control signal of a high
level in response to the sensing result signal of a high level from
the output device 302b to the base of the npn transistor of the
driver 308 through the base resistor R3.
The npn transistor Q2 turns on and drives the BLDC air curtain
fan 304 for 10 seconds to thereby refrigerate the refrigerant compartment
112 at a fixed temperature.
Embodiment 2
FIG. 8 shows a configuration of an air curtain generator for a
refrigerator 80 according to a second embodiment of the present
invention. The air curtain generator 80 for a refrigerator includes
a brushless direct current(BLDC) air curtain fan 802, a driver 804,
a microcomputer 806, and a variable voltage generator 808.
The BLDC air curtain fan 802 blows cool air into a refrigerant
compartment 112 in order to generate air curtain in the refrigerant
compartment 112. The driver 804 drives the BLDC air curtain fan
802. The BLDC air curtain fan 802 has the same configuration and
function as those of the BLDC air curtain fan 302 shown in FIG.
3.
The microcomputer 806 controls an operation of the driver 704.
The microcomputer 806 judges a state of the refrigerant compartment
112 and generates a pulse width modulation signal PWM having different
pulse widths according to the judgement result. FIG. 9A shows a
first pulse width modulation signal PWM1 having a first pulse width
t1 the microcomputer 806 outputs when the refrigerant compartment
door 118 is opened or a refrigeration is performed at high speed.
FIG. 9B shows a second pulse width modulation signal PWM2 having
a second pulse width t2 the microcomputer 806 outputs when an open
refrigerant compartment door 118 is closed. FIG. 9C shows a third
pulse width modulation signal PWM3 having a third pulse width t3
the microcomputer 806 outputs when an normal operation of a refrigerator
is carried out.
The variable voltage generator 808 generates a voltage for controlling
a rotating speed of the BLDC air curtain fan 702 which is variable
according the pulse widths of the pulse width modulation signal
PWM from the microcomputer 806.
Hereinafter, an operation of the air curtain generator 80 according
to a second embodiment of the present invention will be described.
The microcomputer 806 judges a state of the refrigerant compartment
112 and generates a pulse width modulation signal PWM having different
pulse widths according to the judgement result. That is, when the
refrigerant compartment door 118 is opened or refrigeration is performed
at high speed, when an open refrigerant compartment door 118 is
closed, or when an normal operation of a refrigerator is carried
out, the microcomputer 806 outputs a first pulse width modulation
signal PWM1 having a first pulse width t1 as shown in FIG. 8A, a
second pulse width modulation signal PWM2 having a second pulse
width t2 as shown in FIG. 9B, or a third pulse width modulation
signal PWM3 having a third pulse width t3 as shown in FIG. 9C, respectively.
The first, second, or third pulse width modulation signal is provided
to the variable voltage generator 708 through the resistor R3.
The variable voltage generator 808 generates a voltage for controlling
a
rotating speed of the BLDC air curtain fan 802 which is variable
according to the pulse widths of the pulse width modulation signal
PWM from the microcomputer 806.
TABLE 1 ______________________________________ ROTATING APPLIED
SPEED OF VOLTAGE BLDC FAN ______________________________________
REFRIGERANT +15 V.sub.DC HIGH SPEED COMPARTMENT DOOR OPENED OR REFRIGERATION
AT HIGH SPEED REFRIGERANT +12 V.sub.DC MIDDLE SPEED COMPARTMENT
DOOR IS CLOSED NOMRAL +9 V.sub.DC LOW SPEEED OPERATION ______________________________________
Referring to Table 1, when the refrigerant compartment door 118
is opened, the variable voltage generator 808 supplies a DC +15V
to the BLDC air curtain fan 802 and turns on the BLDC air curtain
fan 802 for 70 seconds. From now on, although the refrigerant compartment
door 118 is opened, the BLDC air curtain fan 802 is turned off.
When refrigeration is performed at high speed, the variable voltage
generator 808 supplies a DC +15V to the BLDC air curtain fan 802
and turns on the BLDC air curtain fan 702 at high speed. At this
time, a compressor(not shown) and a cooling fan(not shown) remain
on for 40 minutes. Thereafter when a temperature of the refrigerant
compartment 112.rarw.7.degree. C., the refrigeration at high speed
is cancelled to thereby turn off the BLDC air curtain fan 802.
When an open refrigerant compartment door 118 is closed, the variable
voltage generator 808 supplies a DC +12V to the BLDC air curtain
fan 802 and turns on the BLDC air curtain fan 702 at middle speed
for 10 seconds.
When a normal operation of a refrigerator is carried out, the variable
voltage generator 808 supplies a DC +9V to the BLDC air curtain
fan 802 and turns on the BLDC air curtain fan 702 30 seconds per
1 hour at middle speed for 10 seconds. Thereafter, when a temperature
of the refrigerant compartment 112.rarw.3.degree. C., the BLDC air
curtain fan 802 is turned off.
As mentioned above, the present invention maximizes functions of
an air curtain generator by applying a BLDC air curtain fan having
low noise level, low power consumption, and high efficiency thereto.
The present invention controls a rotating speed of a BLDC air curtain
fan according to a state of the refrigerant compartment to thereby
adjust air speed.
The invention may be embodied in other specific forms without departing
from the spirit or essential characteristics thereof. The present
embodiments are therefore to be considered in all respects as illustrative
and not restrictive, the scope of the invention being indicated
by the appended claims rather than by the foregoing description
and all changes which come within the meaning and range of equivalency
of the claims are therefore intended to be embraced therein. |