[0001] This invention relates to an improvement of the cooling construction of a machine
compartment in a high frequency heating apparatus.
[0002] Conventionally, a machine compartment is provided at one side of a heating chamber
so as to be adjacent thereto in high frequency heating apparatus such as microwave
ovens. A magnetron is provided in the machine compartment and a high voltage transformer
is also provided over the magnetron in the machine compartment. Further, a cooling
fan is provided behind the magnetron and high voltage transformer so that a cooling
air delivered from the cooling fan is directed to both of the magnetron and the high
voltage transformer, thereby cooling them.
[0003] In the above-described conventional construction, the cooling air from the cooling
fan needs to be dissipated so as to be directed to both the magnetron and the high
voltage transformer, resulting in low cooling efficiency. Particularly, a so- called
built-in type wherein the high frequency heating apparatus is built in a cabinet has
recently found popular. Since an air intake efficiency to the machine compartment
is lowered by the cabinet in the case of the built-in type, the cooling efficiency
is further lowered. A large-sized cooling fan needs to be employed to overcome this
problem, which increases the production cost of the high frequency heating apparatus.
[0004] Therefore, an object of the present invention is to provide a high frequency heating
apparatus wherein both of the magnetron and the high voltage transformer provided
in the machine compartment can be cooled efficiently and reasonably, thereby improving
the cooling performance.
[0005] The present invention provides a high frequency heating apparatus comprising an outer
casing, a heating chamber provided within the outer casing, a machine compartment
provided adjacent the heating chamber within the outer casing, a magnetron provided
in the machine compartment for radiating high frequency waves into the heating chamber
so that a food contained in the heating chamber is heated, a high voltage transformer
provided in the machine compartment for applying a high voltage to the magnetron,
a partition member partitioning the interior of the machine compartment into a space
where the magnetron is disposed and the other space where the high voltage transformer
is disposed, the partition member having a ventilation opening, and a cooling fan
provided at the ventilation opening of the partition member so that air in the space
where the high transformer is disposed is taken in and then delivered into the space
where the magnetron is disposed.
[0006] In accordance with the above-described construction, the high voltage transformer
is cooled by air taken in by the cooling fan and the magnetron is cooled by the air
delivered from the cooling fan. Accordingly, the high voltage transformer can efficiently
be cooled by making effective use of the intake air of the cooling fan. Also, the
magnetron can efficiently be cooled by having the air from the cooling fan concentrated
onto it.
[0007] It is preferable that the partition member comprise a duct and the magnetron be enclosed
by the duct. An air guide action of the duct can cause the air delivered from the
cooling fan to be further concentrated onto the magnetron, resulting in further improvement
of the cooling efficiency.
[0008] It is also preferable that the machine compartment have a bottom plate having one
or a plurality of air inlets and a high voltage capacitor be provided so as to face
a flow of air from each air inlet. The high voltage capacitor can also be cooled by
the intake air of the cooling fan efficiently.
[0009] Preferably, the duct may have an open upper side and an open side so that the open
upper side and the open side are closed by an upper side and a side of the machine
compartment respectively, thereby forming a ventilation path. In this case a number
of ventilation apertures may be formed in one side wall of the machine compartment
so that air flowing along the duct is fed into the heating chamber through the ventilation
apertures and an upper wall of the machine compartment may have escape apertures through
which a part of the air flowing along the duct is caused to escape. Consequently,
the heating chamber can be ventilated by feeding the air flowing along the duct into
the heating chamber through the ventilation apertures formed in the side wall of the
machine compartment. Further, since a part of the air flowing along the duct can be
allowed to escape through the escape apertures formed in the upper wall of the machine
compartment, the flow resistance of the air flowing along the duct can be reduced
and an amount of air flowing along the duct can be increased, which can further improve
the cooling performance.
[0010] The magnetron may have a terminal member connected to a secondary side of the high
voltage transformer and the duct may have a hole through which the terminal member
is externally exposed. Consequently, wiring from the high voltage transformer secondary
side to the magnetron terminal member can be performed by viewing through the hole,
which simplifying the wiring work.
[0011] The invention will be described, merely by way of example, with reference to the
accompanying drawings, in which:
FIG. 1 is a longitudinal sectional side view of a machine compartment of a high frequency
heating apparatus of an embodiment in accordance with the invention;
FIG. 2 is a longitudinal sectional rear view of a magnetron and its surrounding portion
of the machine compartment;
FIG. 3 is a top plan view of a duct employed in the high frequency heating apparatus;
and
FIG. 4 is a side view of the duct.
[0012] One embodiment of the present invention will now be described with reference to the
accompanying drawings.
[0013] An outer casing 1 of the high frequency heating apparatus has therein a heating chamber
2 (see FIG. 2) and a machine compartment 3 provided left and right respectively. A
high voltage transformer 5 is provided on a bottom wall 4 within the machine compartment
3 and a high voltage capacitor 6 is provided behind the transformer 5 within the machine
compartment 3. Air inlets 7 are formed in the bottom wall 4 so as to be positioned
before and behind the high voltage transformer 5. Legs 19 are mounted on the outer
bottom wall 4 so as to provide below each air inlet 7 a space sufficient for the air
intake. The high voltage capacitor 6 is disposed so as to face a flow of air taken
in through each air inlet 7.
[0014] A magnetron 9 is mounted on an upper plate 8 of the machine compartment 3 with an
output antenna 9a directed upwards. The magnetron 9 is driven by a high voltage at
the transformer 5 secondary side to radiate high frequency waves from the output antenna
9a. The high frequency waves delivered from the output antenna 9a are guided by a
waveguide 10 mounted on the upper plate 8 into the heating chamber 2.
[0015] The magnetron 9 is enclosed by a duct 11 serving as a partition member partitioning
the machine compartment 3 interior into two compartments. The duct 11 is formed, for
example, of a suitable plastic material so as to have an open upper side and an open
side. The duct 11 is secured by means of screws to a side wall 12 partitioning the
outer casing interior into the heating chamber 2 and the machine compartment 3 and
to the upper plate 8. The open upper side and the open side of the duct 11 are closed
by the side wall 12 and the upper plate 8 such that a ventilation path is formed together
by the duct 11. The duct 11 has a ventilation opening 13 formed in its rear portion.
A motor 15a of a cooling fan 15 is mounted by means of screws on a support flame 14
formed at the ventilation opening 13 so as to be directed upwards. The machine compartment
interior is thus partitioned by the duct 11 into air intake and outlet sides of the
cooling fan 15 such that the high voltage transformer 5 is disposed in the air intake
side and the magnetron 9 in the outlet side.
[0016] A number of ventilation apertures 16 are formed in the side wall 12 of the machine
compartment 3 so as to correspond to outlet side of the duct 11. Air is fed into the
heating chamber 2 through the ventilation apertures 16 during the high frequency heating
to thereby ventilate the heating chamber 2. A damper (not shown) is provided within
the duct 11 for opening and closing the ventilation apertures 16. The damper is closed
in an oven cooking mode wherein a heater (not shown) provided on the back of the heating
chamber 2 is energized so that a heated air is fed into the heating chamber 2. Escape
apertures 17 are formed in the upper plate 8 of the machine compartment 3 so that
a part of the outlet air flowing along the duct 11 is caused to escape through them.
The air from the escape apertures 17 flows rearward along a space between the upper
plate 8 and a ceiling 1 a of the outer casing 1 to be exhausted from an exhaust hole
18 formed in a rear plate 1 b of the outer casing 1.
[0017] The magnetron 9 is provided with a thermal switch 21 for detecting its overheating
condition and a terminal member 22. The thermal switch 21 and the terminal member
22 are exposed outward of the duct 11 through holes 23 and 24 (see FIG. 4) respectively.
The terminal member 22 is connected to the secondary side of the high voltage transformer
5.
[0018] In operation the magnetron 9 is operated during the high frequency heating operation
so that the high frequency waves are radiated into the heating chamber 2 and also,
the cooling fan 15 is driven so that air is taken in through the air intake apertures
7. The air thus taken in flows along the outer surfaces of the high voltage transformer
5, high voltage capacitor 6 and the like, thereby cooling them. Subsequently, the
intake air is caused by an air blowing action of the cooling fan 15 to flow along
the outer periphery of the motor 15a, cooling it. The intake air is then taken in
through the ventilation opening 13 to be delivered into the duct 11. The air delivered
into the duct 11 flows forward along the magnetron 9, cooling it. Subsequently, the
air is fed into the heating chamber 2 through the ventilation apertures 16 after passing
through the magnetron 9, thereby ventilating the heating chamber 2. A part of the
air passing through the magnetron 9 is caused to escape through the escape apertures
17 into the space between the upper plate 8 and the ceiling 1 a to be exhausted through
the exhaust hole 18. Consequently, the flow resistance of the air flowing along the
duct 11 is reduced, which increases an amount of air flowing along the duct 11 and
accordingly, improves the cooling performance.
[0019] In accordance with the above-described construction, the machine compartment 3 interior
is partitioned by the duct 11 into the intake and outlet sides of the cooling fan
15. The high voltage transformer 5 is disposed at the intake side and the magnetron
9 at the outlet side in the machine compartment 3. Accordingly, the high voltage transformer
5 can efficiently be cooled by making effective use of the intake air and the magnetron
9 can efficiently be cooled by concentrating the outlet air delivered from the cooling
fan 15 onto the magnetron 9, which can improve the cooling efficiency in the machine
compartment 3. Therefore, even when the high frequency heating apparatus of the embodiment
is used as the built-in type wherein the apparatus is enclosed in a cabinet (not shown),
a sufficient cooling performance can be secured. Particularly, the cooling fan 15
need not be rendered large-sized and accordingly, the increase in the production cost
can be prevented.
[0020] Since the duct 11 is employed as the partition member partitioning the machine compartment
interior into the intake and outlet sides of the cooling fan 15 and the magnetron
9 is enclosed by the duct 11, the air guide action of the duct 11 can cause the outlet
air delivered from the cooling fan 15 to be further concentrated onto the magnetron
9, resulting in further improvement of the cooling efficiency.
[0021] Since the high voltage capacitor 6 is disposed so as to face a flow of air taken
in through each air inlet 7 formed in the bottom plate 4 of the machine compartment
3, the high voltage capacitor 6 can also be cooled by the intake air of the cooling
fan 15 efficiently.
[0022] Since the escape apertures 17 are formed in the upper plate 8 of the machine compartment
3, a part of air flowing along the duct 11 is allowed to escape through the escape
apertures 17. Consequently, the flow resistance of the air flowing along the duct
11 can be reduced and an amount of air flowing along the duct 11 can be increased,
which can further improve the cooling performance.
[0023] Since the duct 11 is provided with the hole 24 into which the terminal member 22
of the magnetron 9 is inserted so that it is externally exposed, the wiring from the
high voltage transformer secondary side to the magnetron terminal member 22 can be
performed by viewing through the hole 24, which simplifying the wiring work.
[0024] Although the cooling fan 15 is mounted on the duct 11 so as to be directed upwards
in the foregoing embodiment, it may be mounted on the duct 11 so as to be directed
toward the magnetron 9 and inclined forward. Further, the configuration of the duct
11 may be changed and the positions of the cooling fan 15 and the high voltage transformer
5 may be changed.
[0025] The foregoing disclosure and drawings are merely illustrative of the principles of
the present invention and are not to be interpreted in a limiting sense. The only
limitation is to be determined from the scope of the appended claims.
1. A high frequency heating apparatus comprising an outer casing (1), a heating chamber
(2) provided within the outer casing (1), a machine compartment (3) provided adjacent
the heating chamber (2) within the outer casing (1), a magnetron (9) provided in the
machine compartment (3) for radiating high frequency waves into the heating chamber
(2) so that a food contained in the heating chamber (2) is heated, and a high voltage
transformer (5) provided in the machine compartment (3) for applying a high voltage
to the magnetron (9), characterized by a partition member (11) partitioning the interior
of the machine compartment (3) into a space where the magnetron (9) is disposed and
the other space where the high voltage transformer (5) is disposed, the partition
member (11) having a ventilation opening (13) and in that a cooling fan (15) provided
at the ventilation opening (13) of the partition member (11) so that air in the space
where the high transformer (5) is disposed is taken in and then delivered into the
space where the magnetron (9) is disposed.
2. A high frequency heating apparatus according to claim 1, characterized in that
the partition member (11) comprises a duct (11) and the magnetron (9) is enclosed
by the duct (11).
3. A high frequency heating apparatus according to claim 1, characterized in that
the machine compartment (3) has a bottom plate (4) having one or a plurality of air
inlets (7) and a high voltage capacitor (6) is provided so as to face a flow of air
from each air inlet (7).
4. A high frequency heating apparatus according to claim 2, characterized in that
the duct (11) has an open upper side and an open side so that the open upper side
and the open side are closed by an upper side and a side of the machine compartment
(3) respectively, thereby forming a ventilation path, a number of ventilation apertures
(16) are formed in one side wall (12) of the machine compartment (3) so that air flowing
along the duct (11) is fed into the heating chamber (2) through the ventilation apertures
(16), and an upper wall (8) of the machine compartment (3) has escape apertures (17)
through which a part of the air flowing along the duct (11) is caused to escape.
5. A high frequency heating apparatus according to claim 2, characterized in that
the magnetron (9) has a terminal member (22) connected to a secondary side of the
high voltage transformer (5) and the duct (11) has a hole (24) through which the terminal
member (22) is externally exposed.