Electric heating – Microwave heating – Enclosed cavity structure
Reexamination Certificate
1998-11-30
2001-02-20
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
Enclosed cavity structure
C219S757000, C219S746000
Reexamination Certificate
active
06191403
ABSTRACT:
This application is a U.S. National Phase application of PCT International application PCT/JP97/01722.
1. Technical Field
The present invention relates to a high frequency heating cooking apparatus with a heater or a microwave oven, and more particularly to the constitution of its heating compartment and the method of manufacturing the same.
2. Background Art
The constitution of a heating compartment of a conventional high frequency heating cooking apparatus is described below by referring to FIG.
3
and
FIG. 4. A
structural diagram of the heating compartment of the conventional high frequency heating cooking apparatus is shown in
FIG. 3. A
front sectional view of the conventional high frequency heating cooking apparatus is shown in FIG.
4
. In FIG.
3
and
FIG. 4
, the heating compartment is composed of an assembly of a left side wall
101
, a right side wall
101
, an upper wall
103
, a bottom panel
102
, and a back panel
104
. Each member of the compartment is joined by welding or crimping. Side wall
101
is provided with a power feed port
107
for feeding high frequency electromagnetic waves generated by a magnetron
108
into the heating compartment, and an intake hole
105
for ventilation. Back panel
104
is provided with an exhaust hole
106
. The outer side of bottom panel
102
is provided with a lower heater
111
, and the outer side of upper wall
103
is provided, with an upper heater
112
. At the end junction of bottom panel
102
, a flange
110
is provided for preventing the water escaping from junction
109
and propagating into the direction of lower heater
111
.
In such conventional constitution of the heating compartment, however, since upper wall
103
and bottom plate
102
, in which upper heater
112
and lower heater
111
are provided, are exposed to high temperature, stainless steel materials of high heat resistance are needed. On the other hand, right and left side walls
101
are low in temperature, and do not need expensive stainless steel materials.
In the conventional constitution, since left side wall
101
, right side wall
101
, and upper wall
103
form an integral structure, stainless steel materials must be used, resulting in a cost increase.
In side wall
101
and back panel
104
, if plated steel plates other than stainless steel are used, rust is formed in side wall
101
and in portions other than the plated layers. Rust is also formed in the end portion of the holes of power feed port
107
, intake hole
105
, and exhaust hole
106
.
Another problem is the increase of material cost of providing flange
110
to avoid insulation failure and prevent water leaks from junction
109
of side wall
101
and water propagating from bottom panel
102
into lower heater
111
.
It is hence an object of the present invention to provide a high frequency heating cooking apparatus capable of preventing rust, reducing cost, and insulating the heater easily.
DISCLOSURE OF THE INVENTION
A high frequency heating cooking apparatus of the present invention comprises a heating compartment having a left side wall, a right side wall, back side wall, a bottom panel, and a top panel, for containing and heating food therein, a magnetron installed outside of the heating compartment, for generating a high frequency electric power, a duct for leading the high frequency electric power into the heating compartment, and a heater installed at an outside of the heating compartment. The heater is installed outside of at least one of the bottom panel and the top panel. The left side wall, the right side wall, and the back side wall are formed integrally in one plate.
The inner surface of each one of the left side wall, the right side wall, and the back side wall is a treated steel plate.
A manufacturing method of high frequency heating cooking apparatus of the invention comprises:
(1) a step of manufacturing a heating compartment,
(2) a step of installing a magnetron for generating a high frequency electric power outside of the heating compartment,
(3) a step of installing a duct for leading the high frequency electric power into the heating compartment, and
(4) a step of installing a heater outside of the heating compartment.
The heating compartment is manufactured in (a) a step of folding and processing a steel plate to form side walls having a left side wall, a right side wall, and a back side wall, (b) a step of joining a top panel above the walls, (c) a step of joining a bottom panel below the side walls, and (d) a step of placing a door to be opened and closed, before the side walls.
Preferably, each one of the left side wall, the right side wall, and the back side wall does not have a hole or opening cut section end portion .
Preferably, the surface treated steel plate is a plated steel plate having a function of preventing rust.
Preferably, the surface treated steel plate is aluminum plated steel plate.
Preferably, the surface treated steel plate is painted steel plate.
Preferably, the surface treated steel plate is fluorine resin coated steel plate.
Preferably, the top panel is formed of a stainless steel having a function of preventing rust.
Preferably, the top panel has an intake hole, an exhaust hole, and a power feed port for feeding the high frequency electric power into the heating compartment formed at specified positions.
In the above constitution, the side wall of the heating compartment composed of left side wall, right side wall, and back side wall is a surface treated steel plate integrally formed in a pi-form or U-form.
Hence, rust is prevented, and the manufacturing cost is reduced at the same time. More particularly, notable effects are obtained when the surface treated steel plate aluminum plated steel plate or fluorine resin coated steel plate.
Moreover, the top panel is formed of stainless steel, and penetration holes such as power feed opening, intake hole and exhaust hole are formed in the stainless steel, The side wall made of steel plate does not have any penetration hole. Accordingly, if inexpensive plated steel plate is used in the side wall, rust is prevented in the apparatus since it does not have a hole opening cut section end portion.
Still more, the heater is installed outside of the top panel or bottom panel made of stainless steel, and is not installed at the side wall made of steel plate. Hence, if inexpensive plated steel plate is used in the side wall, a reliable heat resistant high frequency heating cooking apparatus can be obtained. As a result, manufacturing cost is lowered.
In addition, the heater is installed at the lower side of the bottom plate. A bead form reducing portion is formed near the end of the inside surface of the bottom panel, preventing water generated inside from passing through the junction part and contacting the heater.
As a result, an excellent electric insulation of the heater is guaranteed.
REFERENCES:
patent: 4481396 (1984-11-01), Matsubayashi et al.
patent: 4675507 (1987-06-01), Akiyoshi et al.
patent: 4680439 (1987-07-01), Millman
patent: 5111013 (1992-05-01), Okada
patent: 51-6553 (1976-01-01), None
patent: 52-93952 (1977-07-01), None
patent: 53-135657 (1978-10-01), None
patent: 55-63329 (1980-05-01), None
patent: 57-21722 (1982-02-01), None
patent: 58-6397 (1983-01-01), None
patent: 60-155430 (1985-10-01), None
patent: 61-3302 (1986-01-01), None
patent: 62-110298 (1987-05-01), None
patent: 2-306578 (1990-12-01), None
patent: 4-244518 (1992-09-01), None
Japanese Search report corresponding to application PCT/JP97/01722 dated Aug. 26, 1997.
English translation of Form PCT/ISA/210.
European Search Report corresponding to application No. EP 97 92 2136 dated Jan. 27, 2000.
Hayakawa Yuji
Hori Ichiro
Leung Philip H.
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
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