Electric heating – Microwave heating – Enclosed cavity structure
Reexamination Certificate
2000-12-19
2002-04-16
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
Enclosed cavity structure
C219S702000, C126S02100R
Reexamination Certificate
active
06373039
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microwave oven, and more particularly, to a damping device in a microwave oven for regulating an air flow to a cooking chamber.
2. Background of the Related Art
The microwave oven is an appliance for disturbing an array of water molecules in food by means a microwave as a heat source, to generate a heat caused by friction between the molecules, for cooking food. The microwave oven has a convection function in which food is cooked, or a surface of food is browned by a heat from a heater, together with the microwave oven function. As shown in
FIG. 1
, the microwave oven is provided with a body
10
, a cooking chamber
20
in one side portion of the body
10
for cooking, an electrical compartment
30
in the other side portion of the body for fitting various components required for driving the device, and a partition wall
40
for partitioning the cooking chamber and the electrical compartment
30
. The electrical compartment
30
is provided with a magnetron
31
for generating a microwave, a transformer
32
for transforming a utility voltage to a voltage required for the magnetron, a cooling fan
33
for cooling the magnetron, and an air duct
34
for guiding an air flow caused by rotation of the cooling fan to a pass through hole(see
41
in
FIG. 2A
) in the partition wall
40
into the cooking chamber. And, there is a heater(not shown) for generating a heat when the convection function is selected.
In the meantime, during the cooking by using the convection function when the cooking is conducted by using a heat from the heater, the microwave oven can not conduct the convection function properly since the air flow from the cooling fan
33
comes into the cooking chamber
20
through the air duct
34
and drops a temperature of the cooking chamber
20
heated by the heater. In order to block the air flow from the cooling fan
33
to the cooking chamber
20
, a damping device is disclosed in Korean Patent No. 99-35944 for selective blocking of the air duct.
As shown in
FIGS. 2A and 2B
, the damping device disclosed in Korean Patent No. 99-35944 is provided with a damper
51
rotatably fitted in the air duct
34
for blocking the air flow toward the cooking chamber, and bidirectional motor
52
fitted to the air duct and coupled with the damper for rotating the damper
51
. There is also a microswitch
53
fitted to one side of the air duct
34
for providing a control signal to a microcomputer(not shown) to control operation of the bidirectional motor
52
, a push button
54
projected from one end of the damper
51
for pressing the microswitch when the damper rotates, and a stopper
55
fitted to a pass through hole
41
side of the partition wall inside of the air duct for stopping rotation of the damper.
The operation of the foregoing damping device will be explained.
First, as shown in
FIG. 2A
, in a convection mode, a regular direction rotation(rotation in a clockwise direction) of the damper
51
by the bidirectional motor
52
until an end
51
a thereof is stopped by the stopper
55
blocks the air duct
34
. Then, the damper blocks the air duct so that the air flow can not come into the cooking chamber
20
, thereby conserving the heat from the heater within the cooking chamber. And, at a moment the air duct
34
is blocked by the damper
51
, the push button
54
is caused to press the microswitch
53
, a signal generated at this moment is provided to the microcomputer, to stop operation of the bidirectional motor
52
.
Second, as shown in
FIG. 2B
, in a microwave mode, the damper
51
is rotated in a reverse direction(a rotation in an anti-clockwise direction) by the bidirectional motor
52
, to open the air duct
34
. According to this, the air flow from the cooling fan
33
, moves in the air duct, enters into the cooking chamber
20
through the pass through hole
41
in the partition wall
40
, and carries vapor in the cooking chamber
20
away from the microwave oven. And, when the air duct
34
is opened as the damper
51
is moved, the push button
54
is freed from the microswitch
53
, and a signal generated in this instance is provided to the microcomputer(not shown), and the microcomputer stops the bidirectional motor
52
.
However, the aforementioned related art damping device has the following problems.
First, in the related art damping device, the bringing into contact of the push button
54
to an actuator
53
a
in the microswitch
53
during the rotation of the damper may cause to provide an excessive force to the actuator
53
a
or generate noise. That is, referring to
FIG. 2A
, it can be known that an extent of actuator
53
a
pressing is dependent on a position of the stopper
55
fitting. Because there may be fabrication errors between components, inclusive of the push button
54
on the damper
51
, the stopper
55
on the partition wall
40
. For an example, if the stopper
55
is fitted closer to the pass through hole
41
side owing to a fabrication error, the damper
51
stops before the push button
54
presses the actuator
53
a
, which makes control of the bidirectional motor impossible. However, since the damping device becomes inoperative if the bidirectional motor is not controllable, the stopper is in general fitted to a place away from the pass through hole side. Consequently, since the damping device comes to a stop after the push button presses the actuator, excessively(see a dashed line in FIG.
2
A), it is liable that an excessive pressure is provided to the microswitch
53
. Moreover, since various mating components are fitted to different members for use in controlling operation of the bidirectional motor
52
, the liability that an excessive pressure is provided to the microswitch
53
becomes further higher after an assembly. That is, the fabrication error in the assembly of the partition wall
40
having the stopper
55
fitted thereto, the damper
51
having the push button
54
fitted thereto, and the air duct
34
having the microswitch
53
fitted thereto may make the liability further higher. Consequently, the excessive pressure to the microswitch
53
may cause problems, not only in a driving performance of the microswitch itself, but also in noise occurrence, or in a lifetime of the microswitch
53
coming from an excessive contact between the push button
54
and the microswitch
53
.
Second, the mounting of the bidirectional motor
52
to an upper part of outside of the air duct
34
in the related art damping device is limited by an oven lamp(not shown) and an upper case
11
in view of space, which prolongs the assembly process, and makes an interchangeability with other large sized components poor, that results in a high cost.
Third, the direct coupling of the damper
51
with the bidirectional motor
52
in the related art damping device fixes a direction of rotation of the damper only by the motor. That is, a regular direction rotation of the damper requires a regular direction rotation of the motor, and a reverse direction rotation of the damper requires a reverse direction rotation of the motor, no motor, but the bidirectional motor, can be used. The use of the bidirectional motor
52
results in a high cost and complicate system.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a damping device in a microwave oven that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a damping device in a microwave oven, which has a smooth operation and a low cost.
Another object of the present invention is to provide a damping device in a microwave oven, which can eliminate an excessive pressure to the microswitch.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained b
Fleshner & Kim LLP
Leung Philip H.
LG Electronics Inc.
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