microwave oven

Abstract

This involves miniaturizing microwave ovens, each equipped with multiple power supply units and microwave sources. [Solution] The microwave oven 10 comprises two magnetrons 30A, 30B, power supply units 32A, 32B, and waveguide 35B. The magnetrons 30A, 30B and the first power supply unit 32A are located outside the first wall 15 of the heating chamber 14, the second waveguide 35B is located outside the second wall 18 of the heating chamber 14 adjacent to the first wall 15, and the second waveguide 35B is mainly located outside the second wall 18.

Description

Technical Field

[0001] The present invention relates to a microwave oven.

Background Art

[0002] Patent Document 1 discloses a microwave oven provided with power feeding units that respectively radiate microwaves to the lower wall portion and the upper wall portion of a heating chamber. In this microwave oven, microwave sources for radiating microwaves from the upper and lower power feeding units are respectively arranged outside one of the left and right side wall portions of the heating chamber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the microwave oven of Patent Document 1, in addition to the space for arranging the lower power feeding unit and the upper power feeding unit outside the lower wall portion and the upper wall portion of the heating chamber, it is necessary to secure a dedicated space for arranging a pair of microwave sources on the side wall portion. Therefore, since the exterior body of the microwave oven becomes large, there is room for improvement in terms of miniaturization.

[0005] An object of the present invention is to miniaturize a microwave oven provided with a plurality of power feeding units and microwave sources respectively.

Means for Solving the Problems

[0006] One aspect of the present invention provides a microwave oven comprising: a heating chamber defined by a plurality of walls that close the top, bottom, left, right, and rear, and a front door; a first microwave source and a second microwave source located outside the first wall among the plurality of walls; a first power supply unit located outside the first wall and radiating microwaves emitted by the first microwave source through the first wall into the heating chamber; a second power supply unit located outside the second wall adjacent to the first wall among the plurality of walls and radiating microwaves emitted by the second microwave source through the second wall into the heating chamber; and a waveguide extending from the second microwave source to the second power supply unit.

[0007] Two microwave sources and a first power supply unit are located on the first wall, and a second power supply unit is located on the second wall adjacent to the first wall. In other words, there is no dedicated space on the outside of the heating chamber for installing only microwave sources. Therefore, the microwave oven can be made smaller compared to a case where multiple microwave sources are placed on the outside of different walls along with multiple power supply units.

[0008] The second microwave source is positioned along the first side of the first wall such that it corresponds to the second power supply section in the direction in which the first side connected to the second wall extends. This allows the waveguide for the second microwave source to be routed over the shortest possible distance, thus simplifying the length and shape of the waveguide for the second microwave source.

[0009] The first microwave source further includes a waveguide for the first microwave source, which is arranged along the second side of the first wall portion such that it corresponds to the first power supply section in the direction in which the second side intersecting the first side extends, and which extends from the first microwave source to the first power supply section. This allows the waveguide for the first microwave source to be routed over the shortest possible distance, thus simplifying the length and shape of the waveguide for the first microwave source.

[0010] With respect to the second microwave source, a first inverter circuit for operating the first microwave source is positioned adjacent to it on the side of the first microwave source in the direction in which the first side extends, and a second inverter circuit for operating the second microwave source is positioned adjacent to it on the side of the second microwave source opposite to the first inverter circuit in the direction in which the first side extends. In other words, all major components except the second power supply unit are concentrated on the outside of the first wall. Therefore, there is no need to secure a large installation space in the part of the heating chamber other than the first wall, which allows for a smaller microwave oven.

[0011] The first wall is the lower wall, the second wall is the rear wall, the first power supply unit is located in the center of the lower wall, and the second power supply unit is located in the center of the rear wall in the left-right direction. The lower wall and rear wall are closer to the object to be heated compared to the side walls, and the distance to the object to be heated is more stable, so it is possible to concentrate the microwaves that diffuse as they move away from the power supply unit onto the object to be heated. Therefore, the heating efficiency of the object to be heated can be improved with a simple configuration. Moreover, since the irradiation direction of microwaves from the first microwave source and the irradiation direction of microwaves from the second microwave source are different, uneven heating of the object to be heated can be suppressed. [Effects of the Invention]

[0012] This invention makes it possible to miniaturize a microwave oven equipped with multiple power supply units and microwave sources. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic cross-sectional view of a microwave oven according to an embodiment of the present invention. [Figure 2] Schematic cross-sectional views of the microwave oven shown in Figure 1, cut from different angles. [Figure 3] Block diagram of a microwave oven, as shown in Figure 1. [Figure 4] Figure 1 shows a downward perspective view with the bottom of the microwave oven removed. [Figure 5] A perspective view showing the placement of components on the lower and rear walls of the heating chamber. [Figure 6] Perspective view of the state where the case cover of FIG. 5 is removed. [Figure 7] Exploded perspective view of FIG. 5. [Figure 8] Exploded perspective view seen from a direction different from that of FIG. 7. [Figure 9] Exploded perspective view seen from a direction different from that of FIGS. 6 and 7 excluding the lower wall portion.

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0015] FIGS. 1 and 2 show a microwave oven 10 according to an embodiment of the present invention. In FIGS. 1 and 2, the X direction is the front-rear direction of the microwave oven 10, the direction indicated by the arrow is the rear side, and the direction opposite to the arrow is the front side. The Y direction is the width direction (left-right direction) of the microwave oven 10, the direction indicated by the arrow is the left side, and the direction opposite to the arrow is the right side. The Z direction is the height direction of the microwave oven 10, the direction indicated by the arrow is the upper side, and the direction opposite to the arrow is the lower side.

[0016] Referring to FIGS. 1 to 3, the microwave oven 10 includes a microwave oven main body 12, a heating chamber 14, a front door 25, and a dedicated tray 38 that is detachably arranged in the heating chamber 14. The microwave oven 10 also includes a plurality of heating units 30A, 30B, 36A, 36B, infrared sensors 40A, 40B, a thermistor 41, an operation panel 42, and a control unit 45.

[0017] Each of the plurality of heating units includes two magnetrons (microwave sources) 30A, 30B and heaters 36A, 36B. The control unit 45 operates either the magnetrons 30A, 30B or the heaters 36A, 36B according to the heat treatment selected by the operation of the operation panel 42, and heats the objects to be heated 1, 2 in the heating chamber 14. In this specification, the object to be heated 1 means the food placed on the tray 38 in the heating chamber 14, and the object to be heated 2 means the food placed on the lower wall portion 15 in the heating chamber 14.

[0018] The magnetrons 30A and 30B are respectively connected to the control unit 45 via the inverter circuits 31A and 31B, and are individually operated by the control of the inverter circuits 31A and 31B by the control unit 45. Each of the individual magnetrons 30A and 30B radiates microwaves into the heating chamber 14 via waveguide tubes 35A and 35B, power feeding units 32A and 32B, and antennas 33A and 33B that are rotatable by motors 34A and 34B. In the present embodiment, the arrangement of two magnetrons 30A and 30B, inverter circuits 31A and 31B, and power feeding units 32A and 32B with respect to the heating chamber 14 is improved to reduce the size of the microwave oven 10.

[0019] Hereinafter, the configuration of the microwave oven 10 will be specifically described.

[0020] Referring to FIGS. 1 and 2, the microwave oven main body 12 includes a heating chamber 14 inside an exterior body 13. The heating chamber 14 is a rectangular parallelepiped space, and is defined by a rectangular bottom wall portion (first wall portion) 15, an upper wall portion 16, a pair of side wall portions 17, a rear wall portion (second wall portion) 18, and a front door 25. Among them, the upper wall portion 16 and the pair of side wall portions 17 are each constituted by a metal plate that is a microwave reflector.

[0021] The bottom wall portion 15 and the rear wall portion 18 each include a wall main body portion 19 and a discharge portion 20. The wall main body portion 19 is constituted by a metal plate that is a microwave reflector, and includes a recess 19a that is recessed outward from inside the heating chamber 14. The discharge portion 20 is constituted by a ceramic, glass, or resin that is a microwave transmitter, and is fitted into the recess 19a. The discharge portion 20 of the bottom wall portion 15 is provided in the central region of the bottom wall portion 15. The ratio of the area occupied by the discharge portion 20 of the bottom wall portion 15 to the total area of the bottom wall portion 15 is more than half (for example, 80%). The discharge portion 20 of the rear wall portion 18 is provided in the upper region of the rear wall portion 18. The ratio of the area occupied by the discharge portion 20 of the rear wall portion 18 to the total area of the rear wall portion 18 is less than half (for example, 35%).

[0022] Each of the pair of side walls 17 is provided with a pair of guide rails 21, 22, and 23 for positioning the tray 38. Of these, the intermediate guide rail 21 is positioned so that the bottom surface of the tray 38 is approximately in the center of the total height of the heating chamber 14. The lower guide rail 22 is provided between the intermediate guide rail 21 and the lower wall 15. The upper guide rail 23 is provided between the intermediate guide rail 21 and the upper wall 16. Guide rails 21 to 23 are all formed in the shape of a right triangle with their upper ends extending along the XY plane. The number of guide rails is not limited to three sets; it may be two sets or less, or four sets or more.

[0023] The front door 25 is attached to the front of the outer casing 13 and retractably closes the front opening of the heating chamber 14. The front door 25 is attached to the lower part of the outer casing 13 and is rotatable around a pivot axis (not shown) that extends in the width direction. However, the front door 25 may also be rotatable around a pivot axis that extends in the height direction, as long as it is configured to open and close the opening of the heating chamber 14.

[0024] The front door 25 comprises a door body 26 that does not allow visibility into the heating chamber 14, and a window portion 27 that allows visibility into the heating chamber 14. The door body 26 is made of a metal plate which is a microwave reflector. The window portion 27 is made of transparent glass or resin which is a microwave permeable material. The window portion 27 is provided with a reflective layer 28 that can reflect microwaves. The reflective layer 28 is made of perforated metal with numerous holes to ensure visibility.

[0025] Referring to Figures 1 to 3, the magnetrons 30A and 30B are operated by inverter circuits 31A and 31B as described above, and radiate microwaves into the heating chamber 14 via waveguides 35A and 35B, feed units 32A and 32B, and antennas 33A and 33B. The lower magnetron (first microwave source) 30A radiates microwaves into the heating chamber 14 via the lower wall 15, heating the object to be heated 1 or 2. The rear magnetron (second microwave source) 30B radiates microwaves into the heating chamber 14 via the rear wall 18, heating the object to be heated 1.

[0026] The magnetrons 30A and 30B, inverter circuits 31A and 31B, the lower power supply unit (first power supply unit) 32A, and the lower waveguide (first waveguide) 35A are respectively located in the installation space 24A below the lower wall 15. The rear power supply unit (second power supply unit) 32B is located in the installation space 24B behind the rear wall 15. The rear waveguide (second waveguide) 35B spans both installation spaces 24A and 24B. Installation space 24A is the space between the lower wall 15 of the heating chamber 14 and the bottom wall 13a of the outer casing 13. Installation space 24B is the space between the rear wall 15 of the heating chamber 14 and the rear wall 13b of the outer casing 13. The specific arrangement of the magnetrons 30A and 30B, inverter circuits 31A and 31B, power supply sections 32A and 32B, and waveguides 35A and 35B will be described in detail later.

[0027] The upper heater 36A is a heating unit that heats the object to be heated 1 inside the heating chamber 14 by radiant heat, and is connected to the control unit 45. The upper heater 36A is made of a sheet-shaped mica heater and is laid on the upper side (outside the heating chamber 14) of the flat upper wall portion 16 of the heating chamber 14. The upper heater 36A may be made of a tube heater such as a quartz tube heater or an Incoloy heater and may be arranged on the lower side (inside the heating chamber 14) of the upper wall portion 16.

[0028] The lower heater 36B is a heating unit that heats the object to be heated 2 inside the heating chamber 14 by radiant heat, and is connected to the control unit 45. The lower heater 36B is made up of a tube heater such as a quartz tube heater and is positioned in a recess 19a of the lower wall portion 15 of the heating chamber 14 so as to surround the bottom antenna 33A. The lower heater 36B may be made up of an Incoloy heater or a mica heater.

[0029] The tray 38 is configured to place the object to be heated 1 inside the heating chamber 14, and is selectively and detachably positioned on one of the intermediate guide rail 21, the lower guide rail 22, or the upper guide rail 23. The lower end of the discharge section 20 of the rear wall section 18 is located at the upper end of the tray 38 positioned on the intermediate guide rail 21.

[0030] The tray 38 can be a heating tray, a transparent tray, or a reflective tray. The heating tray is configured to generate heat from microwaves radiated from the power supply units 32A and 32B. The transparent tray is configured to allow microwaves radiated from the power supply units 32A and 32B to pass through. The reflective tray is configured to reflect microwaves radiated from the power supply units 32A and 32B without allowing them to pass through. When a reflective tray is used, the inside of the heating chamber 14 can be divided vertically with the tray 38 as the boundary, and this is particularly effective when placed on the intermediate guide rail 21, as the magnetrons 30A and 30B can individually control the heating of the upper and lower objects 1 and 2.

[0031] Referring to Figures 2 and 3, the lower infrared sensor 40A is a temperature detection unit that detects the temperature of the object to be heated 2, which is located in the center of the lower wall 15 of the heating chamber 14. The upper infrared sensor 40B is a temperature detection unit for detecting the temperature of the object to be heated 1, which is located in the center of the tray 38 inside the heating chamber 14. The infrared sensors 40A and 40B are monocular thermopile type with one infrared detection element. The infrared sensors 40A and 40B may also be multi-lens thermopile type with multiple infrared detection elements. Furthermore, the infrared sensors 40A and 40B may be movable, allowing the detection direction to be changed.

[0032] The infrared sensors 40A and 40B are mounted on the outside of one of the pair of side wall sections 17 (the right side in Figure 2) with a vertical gap between them, and are connected to the control unit 45, respectively. The lower infrared sensor 40A is positioned in a recess of the intermediate guide rail 21 and faces the inside of the heating chamber 14 through a through hole (not shown). The upper infrared sensor 40B is positioned on the outside of the side wall section 17 between the upper guide rail 23 and the upper wall section 16 and faces the inside of the heating chamber 14 through a through hole (not shown).

[0033] The thermistor 41 is a steam temperature detection unit that detects the temperature of the steam inside the heating chamber 14 and is connected to the control unit 45. The thermistor 41 is positioned above the upper wall 16, and the detection unit is located at the corner of the heating chamber 14 defined by the upper wall 16, the rear wall 18, and the right side wall 17.

[0034] The control panel 42 comprises a liquid crystal panel 43 and an operating unit 44 including switches, and is connected to the control unit 45. The control panel 42 is located on one side (right side) of the front door 25 (see Figure 4). The liquid crystal panel 43 displays the selected state of the heating treatment and the execution state of the heating treatment as performed by the operation of the operating unit 44. The operating unit 44 consists of, for example, a rotary push switch, and allows selection of one of several types of heating treatments.

[0035] The control unit 45 is composed of one or more microcomputers and other electronic devices. The control unit 45 includes a memory 46 and a timer 47. The memory 46 stores programs for performing multiple types of heating treatments, as well as setting values ​​(temperature, time, etc.) used in the programs. The timer 47 measures the execution time of each individual process of the heating treatment.

[0036] The control unit 45 individually controls the magnetrons 30A, 30B and heaters 36A, 36B according to a program determined according to the selected heating treatment, and heats the objects to be heated 1, 2. The heating treatments include microwave heating, combined heating, and heater heating. In microwave heating, the magnetrons 30A, 30B are controlled based on the detection results of the infrared sensors 40A, 40B and the thermistor 41, respectively, and the objects to be heated 1, 2 are heated by microwaves. In combined heating, the magnetrons 30A, 30B and heaters 36A, 36B are controlled based only on the detection result of the thermistor 41, and the object to be heated 1 is heated by microwaves and radiant heat. In heater heating, the heaters 36A, 36B are controlled based only on the detection result of the thermistor 41, and the object to be heated 1 is heated by radiant heat.

[0037] Next, the arrangement of the magnetrons 30A and 30B, inverter circuits 31A and 31B, power supply units 32A and 32B, and waveguides 35A and 35B will be explained in detail.

[0038] Referring to Figures 4 to 6, the lower wall portion 15 of the heating chamber 14 is rectangular in shape and extends along the XY plane. The rear wall portion 18 is joined to the rear edge (first edge) 15a of the lower wall portion 15, which extends in the width direction. The left side wall portion 17 is joined to the left edge (second edge) 15b, which extends in the front-to-back direction perpendicular to the rear edge 15a. The right side wall portion 17 is joined to the right edge (fourth edge) 15c, which extends in the front-to-back direction opposite to the left edge 15b. The front frame, which overlaps with the closed front door 25, is joined to the front edge (third edge) 15d, which extends in the width direction opposite to the rear edge 15a. Flange portions protrude from each of the sides 15a to 15d of the lower wall portion 15. The rear wall portion 18 is rectangular in shape and extends along the YZ plane adjacent to the lower wall portion 15.

[0039] Referring to Figures 1 and 2, the power supply units 32A and 32B are located in adjacent wall sections 15 and 18 among the multiple wall sections 15 to 18. The power supply units 32A and 32B are cylindrical and penetrate the bottom of the recesses 19a in the lower wall section 15 and the rear wall section 18, and are located within the recesses 19a. Of these, the lower power supply unit 32A is located in the center of the front-rear and left-right directions, on the outer center of the lower wall section 15. This position corresponds to the position of the lower motor 34A in Figure 5. The rear power supply unit 32B is located in the center of the left-right direction of the rear wall section 18. Furthermore, the rear power supply unit 32B is located above the center in the height direction, more specifically, at a height of three-quarters of the way up from the lower wall section 15 between the lower wall section 15 and the upper wall section 16. This position corresponds to the position of the rear motor 34B in Figure 5.

[0040] In this case, the microwave oven 10 is often installed in a dedicated space provided in the kitchen cupboard. The depth of the installation space is generally determined based on the usability of the kitchen where the cupboard is installed. The height of the installation space is generally determined based on the storage capacity of dishes. On the other hand, the width of the cupboard, including the installation space, can be selected by the user according to their preferences, taking into account the size of the kitchen.

[0041] The depth (front-to-back dimension) and height (height dimension) of the microwave oven 10 are determined based on the dimensions of the installation space in the cupboard. On the other hand, the width of the microwave oven 10 is determined according to the capacity of the heating chamber 14 it forms, and as the capacity increases, the width increases, and the shape of the heating chamber 14 becomes wider. In other words, the depth and height of the microwave oven 10 are highly constant, while the width of the microwave oven 10 is highly variable. In addition, the distance from the bottom wall 15 and the rear wall 18 to the objects to be heated 1 and 2 placed inside the heating chamber 14 is often shorter than the distance from the side wall 17.

[0042] On the other hand, the microwaves radiated into the heating chamber 14 from the power supply units 32A and 32B diffuse as they move away from the power supply units 32A and 32B. In other words, the microwaves are more likely to irradiate the objects to be heated 1 and 2 when they are close to the power supply units 32A and 32B, and less likely to irradiate the objects to be heated 1 and 2 as they move away from the power supply units 32A and 32B. In this embodiment, the power supply units 32A and 32B are positioned on the lower wall 15 and the rear wall 18, respectively, which are closer to the objects to be heated 1 and 2 than the distance from the side wall 17. Therefore, the microwaves can be concentrated on the objects to be heated 1 and 2, thereby improving the heating efficiency of the objects to be heated 1 and 2. Moreover, since the direction of microwave irradiation from the lower magnetron 30A and the direction of microwave irradiation from the rear magnetron 30B are different, uneven heating of the objects to be heated 1 and 2 can be suppressed.

[0043] Referring to Figures 6 to 8, both magnetrons 30A and 30B are located on the lower wall portion 15 where the power supply units 32A and 32B are located. The lower magnetron 30A is located in the center of the lower wall portion 15 in the front-to-back direction where the left side 15b extends, corresponding to the lower power supply unit 32A, and is positioned adjacent to it along the left side 15b. In other words, the lower magnetron 30A is mounted at the position that is the shortest distance from the lower power supply unit 32A. The rear magnetron 30B is located in the center of the lower wall portion 15 in the width direction where the rear side 15a extends, corresponding to the rear power supply unit 32B, and is positioned adjacent to it along the rear side 15a. In other words, the rear magnetron 30B is mounted at the position that is the shortest distance from the rear power supply unit 32B.

[0044] Continuing to refer to Figures 6 to 8, both inverter circuits 31A and 31B are located in the lower wall section 15 where the magnetrons 30A and 30B are positioned. The lower inverter circuit (first inverter circuit) 31A is connected to the lower magnetron 30A and operates the lower magnetron 30A. The rear inverter circuit (second inverter circuit) 31B is connected to the rear magnetron 30B and operates the rear magnetron 30B.

[0045] The lower inverter circuit 31A is positioned behind the lower magnetron 30A and adjacent to the left side of the rear magnetron 30B. In other words, the lower inverter circuit 31A is positioned at the corner of the rear edge 15a and the left edge 15b of the lower wall 15, and is positioned adjacent to both edges 15a and 15b. The rear inverter circuit 31B is positioned adjacent to the right side of the rear magnetron 30B. In other words, the rear inverter circuit 31B is adjacent to the rear magnetron 30B on the opposite side from the lower inverter circuit 31A, and is positioned adjacent to the rear edge 15a of the lower wall 15.

[0046] Referring to Figures 1, 5, and 6, waveguides 35A and 35B are composed of metal plates that act as microwave reflectors. Waveguides 35A and 35B extend from magnetrons 30A and 30B to feed points 32A and 32B, transmitting microwaves output by magnetrons 30A and 30B to feed points 32A and 32B.

[0047] The lower waveguide 35A is positioned below the recess 19a of the lower wall 15, extends in the width direction relative to the lower wall 15, and is used for the lower magnetron 30A. The lower magnetron 30A is positioned at one end of the lower waveguide 35A, and the lower power supply unit 32A is positioned at the other end of the lower waveguide 35A. The rear waveguide 35B is positioned from the lower wall 15 to the rear side of the recess 19a of the rear wall 18, extends in the height direction relative to the rear wall 18, and is used for the rear magnetron 30A. In other words, the rear waveguide 35B is positioned across the installation spaces 24A and 24B. The rear magnetron 30B is positioned at one end of the rear waveguide 35B, and the rear power supply unit 32B is positioned at the other end of the rear waveguide 35B.

[0048] Referring to Figures 6 to 8, the control board 50 is located in the front right region of the lower wall 15, where the magnetrons 30A, 30B, inverter circuits 31A, 31B, power supply unit 32A, and waveguide 35A are not located. Multiple electronic components, including a control unit 45 (see Figure 3), are mounted on the control board 50. The control board 50 is positioned along the right side 15c and front side 15d of the lower wall 15 so as to be adjacent to the magnetrons 30A, 30B and inverter circuit 31A via waveguide 35A including power supply unit 32A, and directly adjacent to inverter circuit 31B.

[0049] Below the lower wall 15 of the heating chamber 14, fans 52A to 52D are further arranged to individually cool the heat-generating components that reach higher temperatures than the control board 50, namely the magnetrons 30A and 30B and the inverter circuits 31A and 31B. Of these, fans 52B to 52D, excluding fan 52A which cools the lower magnetron 30A, also serve to cool the control board 50. Specifically, this is as follows:

[0050] Referring to Figures 6 to 9, the fan (fourth fan) 52A is positioned adjacent to the front of the lower magnetron (fourth heat-generating component) 30A and cools the lower magnetron 30A. Specifically, the lower magnetron 30A comprises an input section 30a connected to the lower inverter circuit 31A and an output section 30b that generates heat by outputting microwaves, with the output section 30b being located inside a duct-shaped casing 30c. The fan 52A is a propeller fan and is located inside an intake duct 53 positioned adjacent to the front of the casing 30c. The intake duct 53 is cylindrical and consists of two divided sections 53a and 53b. An outlet duct 54 is located at the rear of the casing 30c. The outlet duct 54 is configured so that air is sent out to the left front by the fan 52A.

[0051] The fan 52A configured in this way draws air in from the front of the lower wall section 15 through the intake duct 53 and sends it into the casing 30c. As a result, the air heated by the cooling of the output section 30b is sent to the left front side of the lower wall section 15 through the discharge duct 54. Therefore, the heated air is not sent to the lower inverter circuit 31A located behind the lower magnetron 30A.

[0052] The fan (second fan) 52B is positioned adjacent to the right side of the rear magnetron (second heat-generating component) 30B and cools the rear magnetron 30B. The rear magnetron 30B, like the lower magnetron 30A, comprises an input section 30a, an output section 30b, and a casing 30c. The fan 52B is a propeller fan and is located in the duct section 57f of casing 57, which is positioned adjacent to the right side of casing 30c. Casing 57 houses the rear inverter circuit 31B and will be described in detail later. A discharge duct 55 is located on the left side of casing 30c. The discharge duct 55 is configured so that air is sent to the rear by the fan 52B.

[0053] The fan 52B configured in this way draws air in from the front of the lower wall 15 through the duct section 57f and sends it into the casing 30c. As a result, the air heated by the cooling of the output section 30b is sent to the rear of the lower wall 15 through the discharge duct 55. Therefore, the heated air is not sent to the lower inverter circuit 31A on the left side of the rear magnetron 30B. In addition, the control board 50 is located upstream of the duct section 57f. Therefore, the fan 52B draws air through the surface of the control board 50. In other words, the fan 52B cools the control board 50 with the drawn-in air, and then cools the rear magnetron 30B.

[0054] The fan (third fan) 52C is positioned below the lower motor 34A, which is the central region of the lower wall 15, and cools the lower inverter circuit (third heat-generating component) 31A via the duct 56. The fan 52C is a sirocco fan and is connected to one end of the duct 56. The duct 56 is composed of two divided sections 56a and 56b. At the other end of the duct 56, opposite to the end to which the fan 52C is connected, a casing section 56c is formed to house the lower inverter circuit 31A. The casing section 56c is provided with numerous air outlets 56d that blow air out to the rear and left sides, which are outside the casing section 56c.

[0055] The fan 52C configured in this way draws in air from the front of the lower wall 15 and sends it into the casing 56c through the duct 56. As a result, the air heated by the cooling of the lower inverter circuit 31A is sent out from the outlet 56d to the rear and left side of the lower wall 15. Therefore, the heated air is not sent to the magnetrons 30A and 30B adjacent to the lower inverter circuit 31A. Furthermore, the control board 50 is located upstream of the fan 52C. Therefore, the fan 52C cools the control board 50 with the drawn-in air, and then cools the lower inverter circuit 31A.

[0056] The fan (first fan) 52D is positioned adjacent to the front of the rear inverter circuit (first heat-generating component) 31B and cools the rear inverter circuit 31B. The fan 52D is a propeller fan and is housed in a duct-shaped casing 57. The casing 57 is composed of two divided sections 57a and 57b. The casing 57 is provided with a front mounting section 57c for attaching the fan 52D and a housing section 57d for housing the rear inverter circuit 31B. The housing section 57d is provided with numerous outlets 57e for blowing air out to the rear, outside the housing section 57d. On the left side of the housing section 57d, there is a duct section 57f extending in the front-rear direction and a mounting section 57g for attaching the fan 52B.

[0057] The fan 52D configured in this way draws in air from the front of the lower wall 15 and sends it through the casing 57 into the housing 57d. As a result, the air heated by the cooling of the rear inverter circuit 31B is sent out from the outlet 57e to the rear of the lower wall 15. Therefore, the heated air is not sent to the rear magnetron 30B on the left side of the rear inverter circuit 31B. Furthermore, the control board 50 is located upstream of the fan 52D. Therefore, the fan 52D cools the control board 50 with the drawn-in air, and then cools the rear inverter circuit 31B.

[0058] As described above, the cooling path of the magnetron 30A is separated from other components by the intake duct 53, the casing 30c, and the discharge duct 54. The cooling path of the magnetron 30B is separated from other components by the duct section 57f, the casing 30c, and the discharge duct 55. The cooling path of the inverter circuit 31A is separated from other components by the duct 56. The inverter circuit 31B is separated from other components by the casing 57. Therefore, the air heated by the cooling of the high-temperature heat-generating components, the magnetrons 30A and 30B and the inverter circuits 31A and 31B, is not supplied to other components.

[0059] The microwave oven 10 configured in this way has the following features.

[0060] Two magnetrons 30A and 30B and a lower power supply unit 32A are located on the lower wall 15, while a rear power supply unit 32B is located on the rear wall 18 adjacent to the lower wall 15. In other words, there is no dedicated space on the outside of the heating chamber 14 for installing only the magnetrons 30A and 30B. Therefore, the microwave oven 10 can be made smaller compared to the case where multiple magnetrons 30A and 30B are placed on the outside of different walls from the power supply units 32A and 32B.

[0061] Of the lower wall section 15, the rear magnetron 30B is positioned along the rear edge 15a of the lower wall section 15 so as to correspond to the rear power supply section 32B. This allows the rear waveguide 35B to be routed over the shortest distance, thus simplifying the length and shape of the rear waveguide 35B.

[0062] Of the lower wall portion 15, the lower magnetron 30A is positioned along the left side 15b of the lower wall portion 15 so as to correspond to the lower power supply portion 32A, and further comprises a lower waveguide 35A that is different from the rear waveguide 35B that extends from the lower magnetron 30A to the lower power supply portion 32A. This allows the lower waveguide 35A to be routed over the shortest distance, thus simplifying the length and shape of the lower waveguide 35A.

[0063] On the outside of the lower wall section 15, in addition to the two magnetrons 30A and 30B and the lower power supply section 32A, the lower inverter circuit 31A that operates the lower magnetron 30A and the rear inverter circuit 31B that operates the rear magnetron 30B are arranged adjacent to the rear magnetron 30B. In other words, all major components except the rear power supply section 32B are concentrated on the outside of the lower wall section 15. Therefore, since there is no need to secure a large installation space in the part of the heating chamber 14 other than the lower wall section 15, the microwave oven 10 can be made smaller.

[0064] Power supply units 32A and 32B that radiate microwaves are located on the lower wall 15 and the rear wall 18. The lower wall 15 and the rear wall 18 are closer to the objects to be heated 1 and 2 compared to the side wall 17, and the distance to the objects to be heated 1 and 2 is less variable, so it is possible to concentrate the microwaves that diffuse as they move away from the power supply unit 32 onto the objects to be heated. Therefore, the heating efficiency of the objects to be heated 1 and 2 can be improved with a simple configuration. Moreover, since the irradiation direction of microwaves from the lower magnetron 30A and the irradiation direction of microwaves from the rear magnetron 30B are different, uneven heating of the objects to be heated 1 and 2 can be suppressed.

[0065] Furthermore, the present invention is not limited to the configuration of the above-described embodiment, and various modifications are possible.

[0066] For example, the power supply units 32A and 32B may be placed on the upper wall 16 and one of the side walls 17, and the magnetrons 30A and 30B may be placed on the upper wall 16 or the side wall 17. In other words, if the power supply units 32A and 32B are placed on two adjacent walls out of the multiple walls 15 to 18, and two magnetrons 30A and 30B are placed on one of those two walls, the walls on which the power supply units 32A and 32B and the magnetrons 30A and 30B are placed can be changed as needed. In addition, three or more power supply units and magnetrons may be used.

[0067] The arrangement of the magnetrons 30A and 30B and the inverter circuits 31A and 31B relative to the lower wall portion 15 can be changed as needed.

[0068] The lower magnetron 30A may be placed directly below the recess 19a in the lower wall portion 15 of the heating chamber 14, without providing the lower waveguide 35A.

[0069] Fans 52A, 52B, and 52D may be positioned at intervals, not adjacent to the rear inverter circuit 31B, rear magnetron 30B, and lower magnetron 30A, or a centrifugal fan may be used instead of a propeller fan. Fan 52C may be positioned adjacent to the lower inverter circuit 31A, or a centrifugal fan may be used instead of a centrifugal fan. In other words, the arrangement and type of fans 52A to 52D can be changed as needed, as long as the configuration can cool the rear inverter circuit 31B, rear magnetron 30B, lower inverter circuit 31A, and lower magnetron 30A. [Explanation of symbols]

[0070] 1,2 Heated object 10 Microwave 12. Microwave oven unit 13 Exterior 14 Heating cabinet 13a Bottom wall 13b Back wall 15 Lower wall section (first wall section) 15a Rear edge (first edge) 15b Left side (second side) 15c Right side (4th side) 15d Front edge (3rd edge) 16 Upper wall 17 Side wall section 18 Rear wall (second wall) 19 Wall main body 19a Recess 20 Emission part 21 Intermediate guide rail 22 Lower guide rail 23 Upper guide rail 24A, 24B Installation space 25 Front Door 26 Door body 27 Window section 28 Reflective layer 30A lower-voltage magnetron (1st microwave source, 4th heat-generating component) 30B Rear Magnetron (Second Microwave Source, Second Heating Component) 30a Input section 30b Output section 30c casing 31A Downward Inverter Circuit (First Inverter Circuit, Third Heat-Generating Component) 31B Rear inverter circuit (second inverter circuit, first heat-generating component) 32A Downward Power Supply Section (First Power Supply Section) 32B Rear power supply section (second power supply section) 33A Lower antenna 33B Rear Antenna 34A Lower motor 34B Rear Motor 35A Waveguide for lowering (Waveguide for the first microwave source) 35B Waveguide for the rear (Waveguide for the second microwave source) 36A Upper heater 36B Lower heater 38 trays 40A Lower Infrared Sensor 40B Upper Infrared Sensor 41 Thermistor 42 Control Panel 43 LCD panel 44 Control section 45 Control Unit 46 memory 47 Timer 50 Control board 52A Fan (4th Fan) 52B Fan (Second Fan) 52C Fan (3rd Fan) 52D Fan (First Fan) 53 Intake duct 53a,53b split body 54. Discharge duct 55 Outlet duct 56 Duct 56a,56b split body 56c Casing section 56d Air outlet 57 Casing 57a,57b split body 57c Mounting part 57d Storage area 57e Air outlet 57f Duct section 57g Mounting part

Claims

1. A heating chamber defined by multiple walls that enclose the top, bottom, left, right, and rear, and a front door, A first microwave source and a second microwave source are arranged outside the first wall among the plurality of wall portions, A first power supply unit is positioned outside the first wall and radiates microwaves emitted by the first microwave source through the first wall into the heating chamber. A second power supply unit is positioned outside the second wall adjacent to the first wall among the plurality of wall sections, and radiates microwaves emitted by the second microwave source into the heating chamber via the second wall section. A waveguide extending from the second microwave source to the second power supply section and A microwave oven equipped with [a specific feature].

2. The microwave oven according to claim 1, wherein the second microwave source is arranged along the first side of the first wall such that it corresponds to the second power supply unit in the direction in which the first side connected to the second wall extends.

3. The first microwave source is arranged along the second side of the first wall such that it corresponds to the first power supply unit in the direction in which the second side intersects the first side extends. The microwave oven according to claim 2, further comprising a waveguide for the first microwave source extending from the first microwave source to the first power supply unit.

4. With respect to the second microwave source, a first inverter circuit for operating the first microwave source is arranged adjacent to the first microwave source side in the direction in which the first side extends. The microwave oven according to claim 3, wherein a second inverter circuit for operating the second microwave source is arranged adjacent to the second microwave source on the side opposite to the first inverter circuit in the direction in which the first side extends.

5. The first wall portion is the lower wall portion, and the second wall portion is the rear wall portion. The microwave oven according to any one of claims 1 to 4, wherein the first power supply unit is located in the center of the lower wall and the second power supply unit is located in the center of the rear wall in the left-right direction.

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