EP3798518B1

EP3798518B1 - Microwave processing device

Info

Publication number: EP3798518B1
Application number: EP19807988.1A
Authority: EP
Inventors: Yoshiharu Oomori; Mikio Fukui; Daisuke Hosokawa
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2018-05-21
Filing date: 2019-05-15
Publication date: 2022-04-13
Anticipated expiration: 2039-05-15
Also published as: JPWO2019225413A1; EP3798518A4; JP7378019B2; CN111033127A; EP3798518A1; WO2019225413A1; CN111033127B

Description

TECHNICAL FIELD

The present disclosure relates to a microwave treatment device having a heater.

BACKGROUND ART

FIG. 5 is a schematic diagram showing a configuration of conventional microwave treatment device 100. FIG. 6 is a plan view showing ceiling 105a of heating chamber 105 in conventional microwave treatment device 100. As shown in FIG. 5 and FIG. 6, microwave treatment device 100 separately includes radiation region 101 for radiating a microwave and an installation region of heater 102.
Radiation region 101 is disposed so as to occupy most of ceiling 105a. Heater 102 is disposed in a limited range of ceiling 105a so as to surround radiation region 101 separately from radiation region 101. Radiation unit 104 such as a rotating antenna is disposed in radiation region 101. Oscillation unit 103 generates a microwave, and supplies it to radiation unit 104. In this configuration, a microwave is radiated throughout heating chamber 105.
In some microwave treatment devices, a heating element is disposed at a position lower than a rotating antenna, or an end having a strong directivity in the rotating antenna is stopped at a position higher than the heating element (for example, JP 2008 284657 A .
A microwave treatment device described in JP 2008 284657 A tries to achieve an intended heating distribution, by stopping the rotating antenna in the direction in which a surrounding sheath heater is hard to cause trouble and by radiating a microwave.
In the conventional configuration, however, it is difficult to heat heating target objects having various shapes, types, or amounts that are accommodated in a heating chamber, and to obtain a desired state.
In other words, when a sufficient microwave radiation region is secured, the heater installation region is limited. In this case, a sufficient heating performance by the heater cannot be obtained. On the other hand, when a sufficient heater installation region is secured, the radiation region of a microwave is limited. In this case, when a heating target object is installed in a wide range, the heating efficiency decreases or uneven heating occurs, so that a sufficient heating performance by the microwave cannot be obtained.
In order to secure the heating performance by the heater, it is preferable to take a large installation region of the heater using a small antenna. In order to secure the heating performance by a microwave, the radiation region in which an antenna or the like is installed is set large so that the microwave can be radiated in a wide range. In other words, in order to simultaneously secure the heating performance by the heater and the heating performance by the microwave, conflicting problems must be solved.
GB 2 241 615 A describes a heater change-over switch for an electric oven. Heaters are connected in parallel for cooking food in an oven cavity, but can be connected in series to assist a grill heater for grilling food in the oven. A magnetron is operable at two power levels for microwave cooking and can also be used together with the oven and grill heaters for combination cooking. The heaters, an air circulation fan, a food turntable motor, the magnetron, and a magnetron cooling fan are controlled by a microcomputer responsive to a temperature sensing thermistor.

SUMMARY OF THE INVENTION

The invention is defined by the subject-matter of independent claim 1. The dependent claims are directed to advantageous embodiments.

ADVANTAGES OF THE INVENTION

Advantageously, there is provided a microwave treatment device that can heat, as desired, the heating target objects having various shapes, types, or amounts by reconciling the heating performance by the heater and the heating performance by the microwave.
Advantageously, a microwave treatment device includes a heating chamber for storing a heating target object, an oscillation unit for generating a microwave, a radiation unit, and a heater. The heater is disposed in the heating chamber separately from a wall surface of the heating chamber by a predetermined distance, so as to include a flat surface facing the wall surface. The radiation unit is disposed in the heating chamber, and radiates a microwave to the space between the heater and the wall surface so that the microwave propagates through the space.
Advantageously, the space between the flat surface included by the heater and the wall surface of the heating chamber can be used as a waveguide. Thus, the installation region of the heater can be set large using a small antenna, and the radiation region of the microwave can be enlarged. As a result, the heating performance by the heater and the heating performance by the microwave are reconciled, and the heating target object can be heated as desired.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing a configuration of a microwave treatment device in accordance with a first exemplary embodiment of the present disclosure.
FIG. 2 is plan view of a ceiling of a heating chamber in the microwave treatment device in accordance with the first exemplary embodiment.
FIG. 3 is a sectional view taken along line 4-4 shown in FIG. 1 of the microwave treatment device in accordance with the first exemplary embodiment.
FIG. 4 is an enlarged diagram of a radiation unit of a microwave treatment device in accordance with a second exemplary embodiment of the present disclosure.
To be continued on originally filed page 4
FIG. 5 is a schematic diagram showing a configuration of a conventional microwave treatment device.
FIG. 6 is a plan view of a ceiling of a heating chamber in the conventional microwave treatment device.

DESCRIPTION OF EMBODIMENTS

A microwave treatment device of a first aspect of the present disclosure includes a heating chamber for storing a heating target object, an oscillation unit for generating a microwave, a radiation unit, and a heater. The heater is disposed in the heating chamber separately from a wall surface of the heating chamber by a predetermined distance so as to include a flat surface facing the wall surface. The radiation unit is disposed in the heating chamber, and radiates a microwave to the space between the heater and the wall surface so that the microwave propagates through the space.
A microwave treatment device of a second aspect of the present disclosure includes the first aspect, and the radiation unit is a loop antenna having a loop plane perpendicular to the wall surface. The center of the loop plane is located in the space. The microwave having been radiated from the radiation unit propagates through an antenna projection area that includes the loop plane and extends perpendicularly to the loop plane.
A microwave treatment device of a third aspect of the present disclosure includes the second aspect, and the distance between the wall surface and a part of the radiation unit that is farthest from the wall surface in the radiant unit is two times or less of the distance between the wall surface and a part of the heater that is farthest from the wall surface in the heater.
A microwave treatment device of a fourth aspect of the present disclosure includes the second aspect, and the heater crosses the antenna projection area at a plurality of positions.
A microwave treatment device of a fifth aspect of the present disclosure includes the second aspect, and the antenna projection area extends from the loop plane in two directions perpendicular to the loop plane.
A microwave treatment device of a sixth aspect of the present disclosure includes the second aspect, and the heating chamber has a holding tool for holding the heater. The holding tool is disposed outside the antenna projection area.
A microwave treatment device of a seventh aspect of the present disclosure includes the second aspect, and the heating chamber has a drawer for connecting the heater to an external power source. The drawer is disposed outside the antenna projection area.
A microwave treatment device of an eighth aspect of the present disclosure includes the second aspect, and the radiation unit is disposed in a midway between two facing wall surfaces of the heating chamber.
A microwave treatment device of a nineth aspect of the present disclosure includes the second aspect, and one end of a loop antenna is connected to a transmission unit via a connection unit that is disposed on a wall surface of the heating chamber. The other end of the loop antenna is connected to the wall surface in a ground unit that is separate from the connection unit by the distance of one quarter or less of the wavelength of the microwave.
A microwave treatment device of a tenth aspect of the present disclosure includes the second aspect, and the radiation unit has a loop edge disposed in parallel with the wall surface.
A microwave treatment device of an eleventh aspect of the present disclosure includes the second aspect, and the radiation unit has a plurality of loop antennas. The antenna projection areas of the plurality of loop antennas do not overlap each other in the heating chamber.
A microwave treatment device of a twelfth aspect of the present disclosure includes the first aspect, and wall surface is the ceiling of the heating chamber.
Hereinafter, the exemplary embodiments of the present disclosure are described with reference to the accompanying drawings.

FIRST EXEMPLARY EMBODIMENT

FIG. 1 is a schematic diagram showing a configuration of microwave treatment device 50 in accordance with a first exemplary embodiment of the present disclosure. FIG. 2 is a plan view of ceiling 1a of heating chamber 1 in microwave treatment device 50.
As shown in FIG. 1 and FIG. 2, microwave treatment device 50 includes heating chamber 1 for accommodating heating target object 2, oscillation unit 3, antenna 4, heater 5, and transmission line 6.
Oscillation unit 3 has a semiconductor amplifier, for example, and generates a microwave. Transmission line 6 transmits the microwave generated by oscillation unit 3 to antennas 4 via connection units 6a disposed in ceiling 1a. Antennas 4 radiate, into heating chamber 1, the microwave transmitted through transmission line 6. Heaters 5 are sheath heaters. Heaters 5 are held by holding tools 8 disposed on ceiling 1a, and are disposed near ceiling 1a. In the present exemplary embodiment, antennas 4 and transmission line 6 correspond to the radiation unit and the transmission unit, respectively.
Antennas 4 are disposed on ceiling 1a. Each of antennas 4 has a loop antenna structure in which one end is connected to the transmission line that is connected to oscillation unit 3, and the other end is connected to ceiling 1a and grounded. Loop planes 4a of antennas 4 are perpendicular to ceiling 1a.
The microwave generated by oscillation unit 3 generates a high-frequency current flowing through antennas 4. Thus, strong electromagnetic field excitation 9 occurs in loop planes 4a of antennas 4. Electromagnetic field excitation 9 propagates through antenna projection areas 7 extending along straight lines X. Straight lines X pass through the centers of loop planes 4a and are perpendicular to loop planes 4a.
Antenna projection areas 7 include loop planes 4a, and the cross sections perpendicular to straight lines X have the same shape and size as those of loop planes 4a. So to speak, antenna projection areas 7 are trajectories of loop planes 4a when loop planes 4a of antennas 4 are moved virtually along straight lines X.
Heaters 5 are annularly disposed separately from ceiling 1a by an appropriate distance so as to include a flat surface facing ceiling 1a. With the space between ceiling 1a and heaters 5, the propagation directions of the electromagnetic fields radiated by antennas 4 can be aligned. Therefore, in the present exemplary embodiment, this space is used as the waveguide of the microwave. More specifically, antenna projection areas 7 serve as the waveguides. Thus, even when antennas 4 that are smaller are used, the microwave can be propagated to the ends of antenna projection areas 7 shown in FIG. 2, namely to the end of heating chamber 1.
Holding tools 8 are disposed outside antenna projection areas 7. Thus, in antenna projection areas 7 as the waveguides, holding tools 8 neither reflect nor divide the microwave that propagates through the waveguides. As the result, even antennas 4 that are smaller can certainly and efficiently propagate the microwave to the whole waveguides.
FIG. 3 is a sectional view taken along line 4-4 shown in FIG. 1 of microwave treatment device 50. As shown in FIG. 3, heaters 5 are disposed separately, by an appropriate distance, from a wall surface of heating chamber 1 as discussed above. In the present exemplary embodiment, the wall surface is ceiling 1a. Thus, as discussed above, antenna projection areas 7 serve as the waveguides.
Heaters 5 are disposed in a wide range below antenna projection areas 7. Heaters 5 cross the antenna projection areas 7 at a plurality of heater cross sections 15. With this configuration, as shown in arrows 10 of FIG. 3, a part of the microwave propagating through the waveguide branches toward heating target object 2 at heater cross sections 15. In other words, by diffraction and scattering of the microwave occurring around heater 5, a part of the microwave can be separated toward heating target object 2. Thus, the microwave can propagate more evenly through the whole region of the waveguide into heating chamber 1, and heating target object 2 can be efficiently heated.
As shown in FIG. 2, heaters 5 are connected to external power source 20 via drawers 19 disposed on a wall surface of heating chamber 1. In the exemplary embodiment, the wall surface is rear wall surface 1b (see FIG. 3). Drawers 19 are disposed outside antenna projection areas 7. In the present exemplary embodiment, a structure disturbing the propagation of the microwave is not disposed near the terminal end of the space between ceiling 1a and the flat surfaces included by heaters 5. Thus, the waveguide is secured, and the microwave can be propagated in a wide range.
In the present exemplary embodiment, two antennas 4 are disposed so that loop planes 4a are along straight line Y that is the center line in the depth direction of heating chamber 1. In other words, two antennas 4 are disposed in a midway between two facing wall surfaces of heating chamber 1. In the present exemplary embodiment, these two wall surfaces correspond to rear wall surface 1b of heating chamber 1, and inner wall surface (see FIG. 3) of door 21 covering the front opening of heating chamber 1.
Electromagnetic field excitation 9 of antennas 4 having a loop antenna structure propagates from loop planes 4a along two directions (direction 9a and direction 9b) perpendicular to loop planes 4a. In the present exemplary embodiment, the microwave can be propagated evenly and widely. As a result, heating target object 2 can be more evenly heated.
Antenna projection areas 7 of two antennas 4 do not overlap each other in heating chamber 1. In the present exemplary embodiment, by preventing the microwave radiated from two antennas 4 from interfering with each other, the microwave can be propagated throughout heating chamber 1.

SECOND EXEMPLARY EMBODIMENT

FIG. 4 is an enlarged diagram of an upper part of heating chamber 1 in microwave treatment device 50 in accordance with a second exemplary embodiment of the present disclosure.
As shown in FIG. 4, in the present exemplary embodiment, antenna 4 having a loop antenna structure is configured so that antenna center 14 as the center part of the loop is located in the space between the flat surface included by heater 5 and ceiling 1a of heating chamber 1. In this configuration, most of the microwave radiated from antenna 4 can be efficiently propagated to the space between ceiling 1a and the flat surface included by heater 5.
In the present exemplary embodiment, the distance between antenna 4 and ceiling 1a is set at two times or less of the distance between heater 5 and ceiling 1a. More accurately, distance 16 between ceiling 1a and a part of antenna 4 that is farthest from ceiling 1a in antenna 4 is set at two times or less of distance 17 between ceiling 1a and a part of heater 5 that is farthest from ceiling 1a in heater 5.
Thus, antenna center 14 can be disposed in the waveguide formed of heater 5 and ceiling 1a. As a result, much of the microwave excited by antenna 4 can be guided to the waveguide, and hence an efficient heating is achieved.
Generally, in order to prevent a thermal expansion or the like from deforming ceiling 1a, ceiling 1a partially includes an irregularity or inclined surface 11. Inclined surface 11 is a part for absorbing the deformation and is unstable, so that, in the present exemplary embodiment, antenna 4 is disposed on flat portion 12 of ceiling 1a.
As shown in FIG. 4, connection unit 18a is disposed on ceiling 1a. In the present exemplary embodiment, coaxial line 18 is transmission line 6. Coaxial line 18 is connected to oscillation unit 3, and the microwave generated by oscillation unit 3 is transmitted to antenna 4 via connection unit 18a.
One end of antenna 4 is connected to coaxial line 18 via connection unit 18a. The other end of antenna 4 is connected to ceiling 1a at ground unit 13, and is grounded. In the present exemplary embodiment, ground unit 13 is disposed separately from connection unit 18a by the distance of one quarter or less of the wavelength of the microwave. The reason for this is shown below.
When ground unit 13 is disposed separately from connection unit 18a, antenna 4 does not stay in the space below flat portion 12 and arrives at the space below inclined surface 11. In this case, the stability of the radiation performance of antenna 4 is damaged. The high-frequency current flowing from antenna 4 to ground unit 13 returns to the skin earth of coaxial line 18 via ceiling 1a. The electromagnetic field excitation generated by the high-frequency current flowing through ceiling 1a shifts the intended radiation performance of antenna 4.
In the present exemplary embodiment, however, the distance between connection unit 18a and ground unit 13 is set at one quarter or less of the wavelength of the microwave. Thus, the problems of the stability and shift of the radiation performance of antenna 4 can be solved, and efficient heating is achieved. That is because it is desired that the distance between connection unit 18a and ground unit 13 through which the high-frequency current flows is shorter.
In the present exemplary embodiment, antenna 4 has loop edge 4b disposed almost in parallel with inclined surface 11 of heating chamber 1. Thus, when the high-frequency current flows through antenna 4 near the wall of ceiling 1a, the electromagnetic field occurring between antenna 4 and ceiling 1a affects the radiation performance of antenna 4.
In the present exemplary embodiment, by disposing a space having an almost even thickness between antenna 4 and ceiling 1a, the electromagnetic field distribution between ceiling 1a and loop edge 4b of antenna 4 can be made more even. Thus, the influence of the loop antenna on electromagnetic field excitation can be suppressed. As a result, satisfactory radiation performance of antenna 4 can be obtained.
As described above, microwave treatment device 50 in accordance with the present exemplary embodiment uses, as a waveguide, the space between heater 5 and ceiling 1a of heating chamber 1. Thus, antenna 4 can radiate the microwave throughout heating chamber 1. As a result, using a smaller antenna, the heating performance by the heater and the heating performance by the microwave can be reconciled.
Microwave treatment device related to the present disclosure has been described using the present exemplary embodiment. However, the present disclosure is not limited to this. For example, in the present exemplary embodiment, the oscillator of the microwave is formed of a semiconductor. However, another oscillator such as magnetron may be used. In the present exemplary embodiment, the antenna is a loop antenna. However, an antenna having another structure may be used.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to a heating device or a gavage disposal machine that employ dielectric heating.

REFERENCE MARKS IN THE DRAWINGS

1, 105 heating chamber
1a, 105a ceiling
1b rear wall surface
2 heating target object
3, 103 oscillation unit
4 antenna
5, 102 heater
6 transmission line
6a, 18a connection unit
7 antenna projection area
8 holding tool
9 electromagnetic field excitation
9a, 9b direction
10 arrow
11 inclined surface
12 flat portion
13 ground unit
14 antenna center
15 heater cross section
16, 17 distance
18 coaxial line
19 drawer
20 external power source
21 door
50, 100 microwave treatment device
101 radiation region
104 radiation unit

Claims

A microwave treatment (50) device comprising:
a heating chamber (1) configured to accommodate a heating target object (2);

an oscillation unit (3) configured to generate a microwave;

a heater (5) disposed in the heating chamber (1) separately from a wall surface (1a) of the heating chamber (1) by a predetermined distance, the heater (5) include a flat surface facing the wall surface (1a); and

a radiation unit (4) disposed in the heating chamber (1), and configured to radiate the microwave to a space between the heater (5) and the wall surface (1a), thereby propagating the microwave through the space;

characterized in that:
the radiation unit (4) includes a loop antenna having a loop plane (4a) perpendicular to the wall surface (1a),

a center (14) of the loop plane (4a) is located in the space, and

the microwave having been radiated by the radiation unit (4) propagates through an antenna projection area (7), the antenna projection area (7) including the loop plane (4a) and extending perpendicularly to the loop plane (4a).
The microwave treatment device (50) according to claim 1, wherein
a distance (16) between the wall surface (1a) and a part of the radiation unit (4) is two times or less of a distance (17) between the wall surface (1a) and a part of the heater (5), the part of the radiation unit (4) being farthest from the wall surface (1a) in the radiation unit (4), the part of the heater (5) being farthest from the wall surface (1a) in the heater (5).
The microwave treatment device (50) according to claim 1, wherein
the heater (5) crosses the antenna projection area (7) at a plurality of positions.
The microwave treatment device (50) according to claim 1, wherein
the antenna projection area (7) extends from the loop plane (4a) in two directions perpendicular to the loop plane (4a).
The microwave treatment device (50) according to claim 1, wherein
the heating chamber (1) has a holding tool (8) configured to hold the heater (5), and the holding tool (8) is disposed outside the antenna projection area (7).
The microwave treatment device (50) according to claim 1, wherein
the heating chamber (1) has a drawer (19) for coupling the heater (5) to an external power source (20), and

the drawer (19) is disposed outside the antenna projection area (7).
The microwave treatment device (50) according to claim 1, wherein
the radiation unit (4) is disposed in a midway between two facing wall surfaces of the heating chamber (1).
The microwave treatment device (50) according to claim 1, further comprising a transmission unit (6) coupled to the oscillation unit (3) and configured to transmit the microwave to the radiation unit (4), wherein
a first end of the loop antenna is coupled to the transmission unit (6) via a connection unit (18a) disposed on the wall surface (1a), and

a second end of the loop antenna is coupled to the wall surface (1a) in a ground unit (13), the ground unit (13) being separate from the connection unit (18a) by a distance of one quarter or less of a wavelength of the microwave.
The microwave treatment device (50) according to claim 1, wherein
the radiation unit (4) has a loop edge (4b) disposed in parallel with the wall surface (1a).
The microwave treatment device (50) according to claim 1, wherein
the radiation unit (4) includes a plurality of loop antennas, and

the antenna projection areas (7) corresponding to the plurality of loop antennas do not overlap each other.
The microwave treatment device (50) according to claim 1, wherein
the wall surface (1a) includes a ceiling of the heating chamber (1).