Driving control circuit of a hood motor

Details Driving control circuit of a hood motor Driving control circuit of a hood motor

2000-02-10

2001-10-16

Masih, Karen (Department: 2837)

Electricity: motive power systems

Limitation of motor load, current, torque or force

C318S772000, C318S806000, C318S739000, C318S749000, C318S740000, C318S751000, C318S778000, C318S785000, C318S786000

Reexamination Certificate

active

06304046

ABSTRACT:

CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from applications for ROTATION SPEED CONTROL CIRCUIT OF A HOOD DC MOTOR FOR A MICROWAVE OVEN OVER THE RANGE earlier filed in the Korean Industrial Property Office on the 5
th
of October 1999 and there duly assigned Ser. Nos. 42864/1999 and 42865/1999.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving control circuit of a hood motor, and more particularly to a driving control circuit of a hood motor for controlling rotational speeds of the hood motor.
2. Description of the Related Art
Generally, a hood motor ventilates heat generated under a microwave oven installed over the range (hereinafter called OTR microwave oven), and the smell of foods cooked by the range. The OTR microwave oven having the hood motor is usually installed over a gas range, performing not only a basic function thereof, i.e., the cooking function using microwaves, but also a ventilating function for venting smoke generated during the cooking operation of the gas range.
FIG. 1
is a view for showing a conventional OTR microwave oven installed, and
FIG. 2
is a view for schematically showing the inner portion of the OTR microwave oven.
As shown in
FIG. 1
, the OTR microwave oven includes a body
10
having a cooking chamber
11
therein. On a lower side of the cooking chamber
11
, a hood lamp
12
is disposed, while vent ducts
14
are disposed on the left and right sides of the cooking chamber
11
.
Further, a hood motor M is installed at the middle rear portion of the cooking chamber
11
, and vent blowers
18
are disposed on the left and right sides of the hood motor M. Upper portions of the vent blowers
18
are connected with a connective tube
20
, and a vent passage
22
.
Accordingly, vapor or smoke generated during the cooking operation of the gas range are drawn into the vent ducts
14
by the rotation of the vent blowers
18
, and are exhausted outside through the connective tube
20
and the vent passage.
FIG. 3
is a view for showing the rotational velocity control circuit of the hood motor shown in FIG.
2
.
As shown in
FIG. 3
, the conventional rotational velocity control circuit of the hood motor includes a power on/off switch
330
, a rotational velocity selecting switch
332
, a temperature sensor
334
, and a hood motor M.
The rotational velocity selecting switch
332
selects the rotational velocity of the hood motor M, while being selectively switched on to a low-velocity contact L for selecting the low velocity mode, or to a high-velocity contact H for selecting the high velocity mode.
The hood motor M includes an alternating current (hereinafter called AC) motor selectively rotated at a low or a high velocity in accordance with the selected mode of the low/high velocity contacts L or H.
The temperature sensor
334
senses the temperature of a driving coil in the hood motor M, and has increasing resistance value corresponding to the rise in temperature.
Meanwhile, the presence of foreign substances in the vent blowers
18
of the hood motor M causes a constraint on the rotation of the hood motor M, and accordingly, the temperature of the driving coil is excessively increased. As a result, the resistance value of the temperature sensor
334
is significantly increased, cutting off the application of AC power to the hood motor M.
The conventional control circuit for controlling the rotational velocity of the hood motor M, however, has shortcomings of high manufacturing cost and a low productivity due to its expensive AC motor and temperature sensor.
Further, in the conventional hood motor control circuit, since the low/high velocity contacts of the rotational velocity selecting switch are formed to be mechanically switched on/off to control the rotational velocity of the hood motor M, there is a high possibility of having poor contacts due to frequent switching, and the danger of fire due to spark at the contacts.
SUMMARY OF THE INVENTION
The present invention has been developed to overcome the above-described problems of the related art, and accordingly, it is an object of the present invention to provide a driving control circuit of a hood motor having a direct current motor as a hood motor, which is capable of not only controlling the rotational velocity of the direct current motor, but also capable of protecting circuit components from possible abnormalities of the motor.
The above object is accomplished by a driving control circuit of a hood motor according to the present invention, including: a hood motor rotatably driven for ventilating the inner portion of a system; rectifier circuit means for rectifying an alternating current voltage into a direct voltage, and for supplying direct current voltage to the hood motor; controlling means for generating a control signal for controlling the operation of the hood motor; and driving circuit means for controlling the operation of the hood motor according to the control signal from the controlling means.
As described above, according to the present invention, the manufacturing cost of the microwave oven can be reduced, while the productivity is improved, and the stable operation of the motor can be guaranteed since the abnormalities thereof such as a poor contact of switch contacts, etc. are prevented. Further, when there is an abnormality in the operation of the hood motor, the circuit is automatically cut off, preventing a possible overload at the motor.


REFERENCES:
patent: 3845373 (1974-10-01), Totsu et al.
patent: 5625538 (1997-04-01), Lee et al.
patent: 6008998 (1999-12-01), Han
patent: 6037576 (2000-03-01), Okabayshi et al.
patent: 6148620 (2000-11-01), Kumagai et al.
patent: 6166929 (2000-12-01), Ma et al.
patent: 6172476 (2001-01-01), Tolbert, Jr. et al.

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