Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Distributed parameter resonator-type magnetron
Reexamination Certificate
1999-11-02
2002-02-26
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Distributed parameter resonator-type magnetron
Reexamination Certificate
active
06351071
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetron apparatus for use in a microwave appliance, such as a microwave oven, and a method for manufacturing the magnetron apparatus.
The above-mentioned magnetron apparatus is a microwave oscillation tube operating at a fundamental frequency of, for example, 2,450 MHz and is used as a high-frequency source in an electric appliance (e.g. microwave appliance) using the microwaves. More specifically, a magnetron apparatus is used for microwave heaters such as microwave oven and industrial heater, or a gas excitation apparatus for lighting a microwave discharge lamp. This kind of magnetron apparatus generally comprises a cathode, a tubular anode disposed around the cathode and a resonant cavity formed in the inner space of the tubular anode. Furthermore, in the magnetron apparatus, as is well known, LC filter circuit components including a capacitor and choke coils are connected to the cathode to prevent leakage of high-frequency noise.
In the above-mentioned magnetron apparatus, the temperature of the cathode becomes high during operation thereof. The heat generated at the cathode heats other components, thereby adversely affecting the components. Therefore, in the magnetron apparatus, technical task must be solved to prevent adverse effects due to temperature rising during operation, thereby to prevent changes in the characteristics of the magnetron apparatus.
As a conventional magnetron apparatus developed to solve the above-mentioned problems, a liquid-cooled magnetron apparatus is disclosed in Japanese Laid-open Patent Application No. Hei 4-4544, for example.
This conventional magnetron apparatus will be described below specifically, referring to FIG.
8
.
FIG. 8
is a partially cutaway sectional view showing a configuration of a conventional magnetron apparatus.
As shown in
FIG. 8
, the conventional magnetron apparatus comprises a magnetron part
51
, a magnetic circuit part
53
for forming a magnetic circuit, and a radio wave leakage prevention part
57
for preventing leakage of high-frequency noise.
The magnetron part
51
comprises a tubular anode
52
and a cathode (not shown) disposed inside the tubular anode
52
, and causes oscillation to generate a microwave having a predetermined fundamental frequency.
The magnetic circuit part
53
comprises magnets
54
a
and
54
b
disposed around the upper and lower opening end portions of the above-mentioned tubular anode
52
, respectively, and a case-shaped yoke
55
containing the tubular anode
52
and the magnets
54
a
and
54
b.
The yoke
55
is provided with a supply port
56
a
for supplying a cooling liquid
60
to the inner space of the yoke
55
and an outlet port
56
b
for discharging the cooling liquid
60
. The inner space of the yoke
55
is sealed with the tubular anode
52
, a rubber packing members
61
, and the magnets
54
a
and
54
b.
An adhesive (not shown) is coated between the yoke
55
and the magnets
54
a
and
54
b.
The inner space of the yoke
55
is filled with the cooling liquid
60
, such as water, thereby directly cooling the tubular anode
52
, the magnets
54
a
and
54
b,
and the yoke
55
.
The radio wave leakage prevention part
57
is provided with a metallic filter case
58
and a capacitor
59
, one end of which is connected to the above-mentioned cathode inside the filter case
58
. The other end of the capacitor
59
is taken out of the filter case
59
as shown in
FIG. 8
, and connected to an electric power source (not shown).
With the above-mentioned configuration, the conventional magnetron apparatus is intended to prevent temperature rising at the tubular anode
52
and the magnets
54
a
and
54
b
during operation, thereby to decrease changes in characteristics.
However, the application voltage (electric power source voltage) of the above-mentioned conventional magnetron apparatus during operation is generally in the range of 4 to 5 kV. For this reason, in the radio wave leakage prevention part
57
of the conventional magnetron apparatus, the distance between the filter case
58
(the ground potential side) and the capacitor
59
(the electric power source potential side) disposed in the filter case
58
is required to be kept at a distance (hereinafter referred to as “an insulation distance”) enough to withstand the above-mentioned application voltage. Therefore, the filter case
58
of the conventional magnetron apparatus cannot be made small, thereby making it difficult to miniaturize the configuration of the magnetron apparatus. Furthermore, if the insulation distance is insufficient, a discharge phenomenon occurs between the filter case
58
and the connection point to the cathode of the capacitor
59
during operation, thereby causing improper apparatus operation.
In addition, in the conventional magnetron apparatus, the heat caused at the cathode is directly transferred to the capacitor
59
, thereby raising the temperature of the capacitor
59
to a high temperature of 120 to 150° C. As a result, the capacitor
59
of the conventional magnetron apparatus is burnt and deteriorated, thereby causing a problem of lowering its noise prevention performance significantly.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a magnetron apparatus that can solve the aforementioned problems in the conventional magnetron apparatus.
In order to achieve the above-mentioned object, the magnetron apparatus of the present invention comprises:
a magnetron having a tubular anode and a cathode,
a magnetic circuit having first and second magnets disposed around the upper and lower opening end portions of the tubular anode, respectively, and a yoke disposed enclosing the tubular anode and the first and second magnets, and
a radio wave leakage preventor having a filter case and LC filter circuit components disposed inside the filter case,
an insulating cooling liquid filled in at least the filter case.
According to the above-mentioned configuration, the adverse influence of temperature rising during operation is lowered, whereby burning and deterioration of the LC filter circuit components are reduced, and the magnetron apparatus can be miniaturized.
A magnetron apparatus according to another aspect of the present invention comprises: the tubular anode of the magnetron has cooling fins around the outer peripheral portion of the tubular anode, beside the aforementioned configuration.
According to the above-mentioned configuration, the temperature rising at the tubular anode and the magnets can be reduced further. In addition, this can reduce drop in the output of the magnetron apparatus.
A magnetron apparatus according to another aspect of the present invention comprises: the insulating cooling liquid is supplied from a supply port, beside the aforementioned configuration.
According to the above-mentioned configuration, the insulating cooling liquid can be supplied easily at the final manufacturing step of the magnetron apparatus, or at the time when the magnetron apparatus is installed in a microwave appliance.
A magnetron apparatus according to another aspect of the present invention comprises: the insulating cooling liquid is discharged from an outlet port, beside the aforementioned configuration.
According to the above-mentioned configuration, the insulating cooling liquid is circulated between the filter case and an outside apparatus, whereby the LC filter circuit components can be cooled efficiently. Furthermore, the temperature of the insulating cooling liquid in the magnetic circuit and the radio wave leakage preventor can be maintained at a constant value at all times. This stabilizes the noise prevention performance and the output performance of the magnetron apparatus.
A magnetron apparatus according to another aspect of the present invention comprises: a cooling liquid storage tank is provided between the supply port and the outlet port, so that the insulating cooling liquid circulates, beside the aforementioned configuration.
According to the above-mentioned configuration, the i
Alemu Ephrem
Matsushita Electric - Industrial Co., Ltd.
Sheridan & Ross P.C.
Wong Don
LandOfFree
Magnetron apparatus and manufacturing method therefor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetron apparatus and manufacturing method therefor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetron apparatus and manufacturing method therefor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2948894