microwave oven

Abstract

To effectively heat a cooked object.SOLUTION: A microwave oven 1 includes: a microwave oven body 10 having a heating chamber 12 defined by walls 13-16 each made of a microwave reflecting body, and a magnetron 30 for heating a cooked object in the heating chamber 12; a door 20 closing an opening 17 of the heating chamber 12; a pair of guide rails 35 provided on a pair of side walls 15 in such a manner of extending in a front and rear direction X respectively; and a plate 40 detachably placed on the pair of guide rails 35 so that the cooked object is placed thereon. Microwaves by the magnetron 30 are emitted between a bottom wall 13 of the heating chamber 12 and the plate 40, and a microwave passing portion 43A through which the microwaves emitted by the magnetron 30 can pass is provided on a rear wall 16 side of the plate 40 placed on the guide rails 35.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Patent Document 1 discloses a microwave oven in which a plate on which food is placed is located close to the rear wall of the heating chamber. In this microwave oven, most of the microwaves irradiated by the magnetron are guided between the plate and an electromagnetic wave reflector, so that food is browned in a short time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 10-149877 Summary of the Invention [Problem to be solved by the invention]

[0004] In the microwave oven of Patent Document 1, most of the microwaves irradiated by the magnetron are guided between the plate and the electromagnetic wave reflector, so the heating of the upper side of the food is insufficient. Therefore, there is room for improvement in the microwave oven of Patent Document 1 with regard to heating of the food.

[0005] An object of the present invention is to provide a microwave oven capable of heating food efficiently. [Means for solving the problem]

[0006] In this specification, unless otherwise specified, the term microwave oven includes those that have an oven function (oven range) and those that have a grill function.

[0007] One aspect of the present invention provides a microwave oven comprising: a microwave oven body having a heating chamber defined by a bottom wall, a top wall, a pair of side walls and a rear wall, each of which is made of a microwave reflector; and a magnetron for heating an item to be cooked in the heating chamber; a door attached to the microwave oven body so as to be openable and closable and closing a front opening of the heating chamber; a pair of guide rails provided on the pair of side walls so as to extend in the front-rear direction, respectively; and a plate detachably disposed on the pair of guide rails and on which the item to be cooked is placed, wherein microwaves from the magnetron are irradiated between the bottom wall of the heating chamber and the plate, and the rear wall side of the plate disposed on the guide rails is provided with a microwave passing portion through which the microwaves irradiated by the magnetron can pass. Here, the rear wall side of the plate includes both a configuration in which a microwave passing portion is provided on the rear wall side of the plate itself, and a configuration in which a microwave passing portion is provided on the rear wall side of the plate.

[0008] All of the walls that define the heating chamber are made of microwave reflectors, and a microwave passing section is provided on the rear wall side of the plate. Therefore, the microwaves irradiated by the magnetron toward the rear wall side are all reflected by the rear wall and a pair of side walls, pass through the microwave passing section, and flow all the way to the upper side of the plate, after which they are further reflected by the top wall and irradiated to the upper side of the food placed on the plate. This makes it possible to heat the food more efficiently.

[0009] The microwave passing portion has a front-rear dimension of 30 mm or more.

[0010] Since the front-rear dimension of the microwave passing portion is 30 mm or more, microwaves can be reliably guided around to the upper side of the plate through the microwave passing portion.

[0011] The microwave passing portion is a gap provided between the plate and the rear wall of the heating chamber.

[0012] Since the microwave passing portion is a gap, microwaves heading toward the rear wall side can be reliably passed to the upper side of the plate.

[0013] At least one of the pair of side walls or at least one of the pair of guide rails is provided with a stopper that restricts rearward movement of the plate.

[0014] The stopper restricts the rearward movement of the plate, so that a gap through which microwaves can pass can be secured between the rear wall and the plate.

[0015] At least a portion of the gap is defined by a recess provided in the rear wall so as to be recessed rearward.

[0016] Since the rear wall is provided with a recess recessed backward, a gap through which microwaves can pass can be secured between the rear wall and the plate.

[0017] The door has a glass window portion having a reflective layer that reflects the microwaves, and the distance between the front end of the plate arranged on the guide rail and the door is equal to or greater than 0 mm and less than 30 mm.

[0018] When microwaves are made to pass through the gap between the door and the plate, they pass near the glass window that allows microwaves to pass through, and are therefore likely to be attenuated. In contrast, in this embodiment, the gap between the door and the plate is set to 0 mm or more and less than 30 mm, which is sufficient to prevent or suppress the passage of microwaves, so most of the microwaves irradiated by the magnetron can be made to pass through the microwave passing portion on the rear wall side of the plate and pass through to the upper side of the plate. This allows the microwaves to be efficiently irradiated to the food, thereby making it possible to efficiently heat the food.

[0019] The microwave oven body includes a heater located above the plate within the heating chamber.

[0020] Since a heater is provided above the plate, the top surface of the food can be browned quickly.

[0021] The plate is made of metal. Here, the metal plate includes an enamel plate having a glassy glaze mainly composed of silica (silicon dioxide) baked onto its surface.

[0022] Because the plate is made of metal, microwaves can pass through the microwave passage to the top of the plate without leaking, allowing the food to be heated efficiently. The metal plate can also be used for heating. This means that there is no need to change the plate depending on the heating course for the food, improving user convenience.

[0023] The device includes a pair of lower guide rails extending in the front-to-rear direction below the guide rails of the pair of side walls, and a lower plate detachably arranged on the pair of lower guide rails and having a front-to-rear dimension longer than the front-to-rear dimension of the plate.

[0024] Since the upper and lower plates are at different distances from the heater, the amount of heat generated by the heater also differs. Therefore, by selectively using the upper or lower plate depending on the food being cooked, it is possible to heat the food in an ideal manner.

[0025] A control unit is provided for switching between microwave heating by the magnetron and heater heating by the heater.

[0026] The unit is equipped with a control unit that automatically switches between microwave heating by the magnetron and heater heating by the heater, allowing ideal heating to be performed depending on the food being cooked, such as cooking the food to the center with microwave heating and quickly browning the surface with heater heating. Effect of the Invention

[0027] The microwave oven of the present invention can heat food efficiently. [Brief description of the drawings]

[0028] [Figure 1] 1 is a perspective view of a microwave oven according to a first embodiment of the present invention. [Diagram 2] 1 is a front view of a microwave oven according to a first embodiment of the present invention. [Diagram 3] FIG. [Figure 4] FIG. 2 is a schematic cross-sectional view taken along line IV-IV in FIG. 1. [Diagram 5] Schematic cross-sectional view taken along line VV in Figure 2. [Figure 6] Schematic cross-sectional view taken along line VI-VI in FIG. 4 . [Figure 7] FIG. 6 is a cross-sectional view similar to FIG. 5, but showing only the upper plate. [Figure 8] FIG. 8 is an enlarged view of part VIII of FIG. 5 . [Figure 9] FIG. [Figure 10] 6 is a cross-sectional view similar to FIG. 5 of a microwave oven according to a second embodiment of the present invention. [Figure 11] 6 is a cross-sectional view similar to FIG. 5 of a microwave oven according to a modified example. [Figure 12] 7 is a cross-sectional view similar to FIG. 6 of a microwave oven according to a modified example. [Figure 13] 7 is a cross-sectional view similar to FIG. 6 of a microwave oven according to another modified example. [Figure 14] Conceptual diagram of the electric and magnetic fields generated in the heating chamber. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0030] (First embodiment) 1 to 3 show a microwave oven 1 according to a first embodiment of the present invention. In each drawing, the X direction is the front-rear direction of the microwave oven body 10, the Y direction is the width direction of the microwave oven body 10, and the Z direction is the height direction of the microwave oven body 10.

[0031] 1 to 3, microwave oven 1 includes microwave oven body 10, door 20 attached to microwave oven body 10 so as to be openable and closable, and two types of plates 40, 45 arranged removably within microwave oven body 10.

[0032] Microwave oven body 10 includes heating chamber 12 in housing 11. Heating chamber 12 is a rectangular parallelepiped space with opening 17 on the front side in Fig. 1. With reference to Figs. 4 and 5, heating chamber 12 is defined by a rectangular bottom wall 13, a top wall 14, a pair of side walls 15, and a rear wall 16. All of these walls 13 to 16 are made of metal plates which are microwave reflectors.

[0033] The bottom wall 13 extends along the XY plane and is supported on the bottom wall of the housing 11 at a predetermined interval by a support frame (not shown). The top wall 14 is disposed opposite the bottom wall 13 in the height direction Z and extends along the XY plane. The pair of side walls 15 face each other in the width direction Y and extend along the XZ plane. The lower ends of the pair of side walls 15 are connected to the bottom wall 13, and the upper ends of the pair of side walls 15 are connected to the top wall 14. The front ends of the bottom wall 13, the top wall 14, and the pair of side walls 15 are connected to the front wall of the housing 11 and define an opening 17 of the heating chamber 12. The rear wall 16 extends along the YZ plane and is connected to the rear ends of the bottom wall 13, the top wall 14, and the pair of side walls 15.

[0034] 1 and 5, the door 20 is attached to the front side of the housing 11 and openably closes the opening 17 of the heating chamber 12. The door 20 is rotatable about a rotation axis (not shown) extending in the width direction Y to an open position shown in Fig. 1 and a closed position shown in Fig. 5. The door 20 includes an opaque metal frame 21 and a window 22 through which the inside of the heating chamber 12 can be seen.

[0035] As shown most clearly in Fig. 5, the window section 22 comprises an inner window 23 facing the heating chamber 12, and an outer window 24 arranged at a distance from the outer side of the inner window 23. Both the inner window 23 and the outer window 24 are made of glass that is capable of transmitting microwaves. A reflective layer 25 that reflects microwaves is provided between the inner window 23 and the outer window 24 and adjacent to the outer side of the inner window 23. The reflective layer 25 is made of a punched metal having a large number of holes, for example, with a diameter of 1 mm, in order to ensure visibility.

[0036] Continuing to refer to Fig. 5, microwave oven body 10 further includes magnetron 30, heater 31, and control unit 33. In addition, microwave oven body 10 includes upper guide rails 35 on which upper plate 40 is disposed, and lower guide rails 38 on which lower plate 45 is disposed.

[0037] The magnetron 30 is disposed between the housing 11 and the heating chamber 12, and uses microwaves to heat the food in the heating chamber 12. More specifically, a power feed port 18 is provided in the center of the bottom wall 13, and a duct 30a is attached to the underside of the power feed port 18. The magnetron 30 is attached within the duct 30a, and is electrically connected to the control unit 33. However, the power feed port 18 may be provided in the rear wall 16 or in one of the pair of side walls 15, as long as it is between the bottom wall 13 and the upper plate 40 of the heating chamber 12.

[0038] The heater 31 is disposed on the top wall 14 side so as to be located above the upper plate 40, and heats the food in the heating chamber 12 by radiant heat. In this embodiment, a pair of heaters 31 are disposed at an interval in the front-rear direction X, and each extends in the width direction Y from one of the pair of side walls 15 to the other. However, only one heater 31 may be provided so as to be located at the center of the upper plate 40 in the front-rear direction X, or three or more heaters 31 may be provided.

[0039] The control unit 33 controls the magnetron 30 and the heater 31 to heat the food in the heating chamber 12. For example, a single microcomputer can be used as the control unit 33. The heating process by the control unit 33 includes a microwave heating course in which only the magnetron 30 is driven until the end of cooking, a heater heating course in which only the heater 31 is driven until the end of cooking, and a combined heating course in which both the magnetron 30 and the heater 31 are driven.

[0040] In the composite heating, the control unit 33 heats the food by, for example, automatically switching between microwave heating by the magnetron 33 and heater heating by the heater 31. Specifically, the magnetron 33 is driven and the food is cooked to the center by microwave heating. When a preset microwave heating time or a microwave heating time set by the user has elapsed, the driving of the magnetron 33 is stopped. Next, the heater 31 is driven and the surface of the food is browned by heater heating. When a preset heater heating time or a heater heating time set by the user has elapsed, the driving of the heater 31 is stopped.

[0041] 4 and 5, the pair of upper guide rails 35 are disposed at the same positions in the height direction Z of the pair of side walls 15, and extend horizontally in the front-rear direction X. Stoppers 36 that restrict rearward movement of the upper plate 40 are provided on the pair of upper guide rails 35. The stoppers 36 protrude inward in the width direction Y from each of the pair of side walls 15.

[0042] The stoppers 36 are provided so as to be located at the rear ends of the pair of upper guide rails 35, respectively, but may be provided at intermediate portions of the pair of upper guide rails 35. Moreover, the stoppers 36 may each protrude upward from the pair of upper guide rails 35. Moreover, the stoppers 36 may be provided on only one of the pair of side walls 15, or only one of the pair of upper guide rails 35.

[0043] 4 and 5, the pair of lower guide rails 38 are disposed below the upper guide rail 35 of the pair of side walls 15 with a gap therebetween. The pair of lower guide rails 38 are disposed at the same position in the height direction Z and extend horizontally in the front-rear direction X. No stoppers for restricting movement are provided on the lower guide rails 38.

[0044] 1 and 3, the upper plate 40 is supported in the heating chamber 12 by being placed on a pair of upper guide rails 35 on both sides. The upper plate 40 can be used in all of the microwave heating course, the heater heating course, and the composite heating course.

[0045] 8 and 9, the upper plate 40 includes a plate body 41 and an insulating cover 42 attached to the outer periphery of the plate body 41.

[0046] The plate body 41 includes a bottom wall portion 41a having a rectangular shape in a plan view, and an outer peripheral wall portion 41b erected on the outer periphery of the bottom wall portion 41a. The bottom wall portion 41a does not have any through holes. The upper end of the outer peripheral wall portion 41b is provided with a curled portion 41c having a substantially cylindrical cross section that is bent inward. The whole including the bottom wall portion 41a, the outer peripheral wall portion 41b, and the curled portion 41c is made of a microwave reflector. For example, the plate body 41 can be made of metal to be a microwave reflector as a whole. Here, the metal plate body 41 includes an enamel plate having a glassy glaze mainly composed of silica (silicon dioxide) baked on its surface. When this enamel plate is used, the insulating cover 42 does not need to be provided.

[0047] The insulating cover 42 is made of insulating heat-resistant rubber or heat-resistant resin, and is provided to prevent discharge during microwave heating by the magnetron 30. The insulating cover 42 includes an annular bottom cover part 42a that covers the outer periphery of the outer surface of the bottom wall part 41a, a side cover part 42b that covers the outer surface of the outer periphery wall part 41b, and an upper cover part 42c that covers the outer surface of the curled part 41c. In this embodiment, the insulating cover 42 is provided in a rectangular tube shape so as to cover the entire periphery of the plate body 41, but it may be provided only on at least the portion of the plate body 41 that contacts and is adjacent to the side wall 15 of the heating chamber 12.

[0048] 1 and 3, the lower plate 45 is supported in the heating chamber 12 by being placed on both sides of the pair of lower guide rails 38. The lower plate 45 can be used only in the heater heating course. The lower plate 45 does not have an insulating cover like the upper plate 40. However, like the upper plate 40, the lower plate 45 may also be provided with an insulating cover.

[0049] The lower plate 45, like the plate body 41 of the upper plate 40, has a bottom wall portion that is rectangular in plan view and an outer peripheral wall portion that is erected on the outer periphery of the bottom wall portion. No through holes are provided in the bottom wall portion. An upper end of the outer peripheral wall portion is provided with a curled portion that is bent inward and has a substantially cylindrical cross section. The entire plate including the bottom wall portion, the outer peripheral wall portion and the curled portion is made of a microwave reflector. For example, by making the lower plate 45 out of metal, the entire plate can be made into a microwave reflector. The metallic lower plate 45 includes an enamel plate having a glassy glaze mainly composed of silica (silicon dioxide) baked onto its surface.

[0050] Next, a specific description will be given of the dimensional settings of the upper plate 40 and the lower plate 45. In the following description, the terms front end and rear end are used for the individual plates 40, 45, but in actual use, the individual plates 40, 45 do not have a distinction between the front side and the rear side.

[0051] 4, 5 and 6, the upper plate 40 has a rectangular shape in plan view with a dimension D1 in the front-rear direction X smaller than a dimension W1 in the width direction Y. The lower plate 45 also has a rectangular shape in plan view with a dimension D2 in the front-rear direction X smaller than a dimension W2 in the width direction Y. The dimension W1 in the width direction Y of the upper plate 40 and the dimension W2 in the width direction Y of the lower plate 45 are the same. The dimension D1 in the front-rear direction X of the upper plate 40 and the dimension D2 in the front-rear direction X of the lower plate 45 are different, and the dimension D2 of the lower plate 45 is longer than the dimension D1 of the upper plate 40. The dimension D2 of the lower plate 45 is set to a length that is slightly smaller than the dimension in the front-rear direction X of the heating chamber 12, that is, the dimension from the inner surface of the rear wall 16 to the inner surface of the door 20, and that ensures a gap that does not interfere with the rear wall 16 and the door 20.

[0052] 5 and 6, a first gap (microwave passing portion) 43A through which microwaves can pass is provided on the rear wall 16 side of the center of the upper plate 40 in the front-rear direction X. More specifically, when the rear end of the upper plate 40 is in contact with the stopper 36, the first gap 43A with a determined interval S1 is formed between the rear end of the upper plate 40 and the rear wall 16 of the heating chamber 12 across the entire width direction Y of the upper plate 40. In other words, the stopper 36 is provided on the upper guide rail 35 so that the first gap 43A with the interval S1 is formed between the rear end of the upper plate 40 and the rear wall 16 of the heating chamber 12. The interval (dimension) S1 of the first gap 43A in the front-rear direction X is 30 mm or more, which allows the microwaves irradiated by the magnetron 30 to pass through without being attenuated. Although there is no upper limit to the spacing S1 of the first gap 43A, if it is made too large, the space on the upper plate 40 for arranging the food to be cooked will become reduced, which is not preferable.

[0053] With the rear end of the upper plate 40 in contact with the stopper 36, a second gap 43B with a determined distance S2 is formed between the front end of the upper plate 40 and the door 20. In other words, the position of the stopper 36 in the front-rear direction X and the dimension D1 in the front-rear direction X of the upper plate 40 are set so that the second gap 43B with the distance S2 is formed between the front end of the upper plate 40 and the door 20. The distance (dimension) S2 in the front-rear direction X of the second gap 43B is equal to or greater than 0 mm and less than 30 mm, which is sufficient to prevent or suppress the passage of the microwaves irradiated by the magnetron 30.

[0054] When the magnetron 30 irradiates microwaves, electromagnetic waves as shown in FIG. 14 are generated in the heating chamber 12, generating electric and magnetic fields with different directions. The strength (amplitude) of these electric and magnetic fields corresponds to the strength at which food is heated. The oscillation frequency of the magnetron 30 is 2450 MHz, so the wavelength (λ) of the electromagnetic waves is about 120 mm. The peak of the electromagnetic waves is one-quarter of the wavelength from the node (zero point), so a gap of 30 mm or more allows the strongest electric and magnetic fields to pass. In the first gap 43A, the interval S1 of the first gap 43A is set to 30 mm or more in order to actively allow the microwaves to pass through. In the second gap 43B, the interval S2 of the second gap 43B is set to 0 mm or more and less than 30 mm in order to prevent or suppress the microwaves from passing through.

[0055] With the lower plate 45 disposed on the lower guide rail 38, a first gap 46A having a distance S3 is formed between the rear end of the lower plate 45 and the rear wall 16 of the heating chamber 12, and a second gap 46B having a distance S4 is formed between the front end of the lower plate 45 and the door 20. The distance S3 in the front-rear direction X of the first gap 46A and the distance S4 in the front-rear direction X of the second gap 46B are both 0 mm or more and less than 30 mm, which is sufficient to prevent or suppress the passage of microwaves irradiated by the magnetron 30. In this embodiment, the total dimension (S3+S4) of the distance S3 of the first gap 46A and the distance S4 of the second gap 46B is set to 0 mm or more and less than 30 mm.

[0056] Next, the heating process performed by the control unit 33 will be described.

[0057] As shown in Fig. 7, in the case of the microwave heating course, an upper plate 40 can be used. When the upper plate 40 is placed on the upper guide rail 35 and the lower plate 45 is not placed on the lower guide rail 38, the inside of the heating chamber 12 is divided into a space A below the upper plate 40 and a space B above the upper plate 40. The lower space A and the upper space B communicate with each other via a first gap portion 43A.

[0058] When microwave heating is performed by the control unit 33, microwaves are radiated radially from the magnetron 30 through the duct 30a and the power supply port 18 into the heating chamber 12, as shown by the dashed line in Fig. 7. The walls 13-16 and the upper plate 40 that define the heating chamber 12 are made of microwave reflectors, and the door 20 has a reflective layer 25 made of a microwave reflector. In addition, the distance S2 (see Fig. 5) of the second gap 43B between the door 20 and the upper plate 40 is 0 mm or more and less than 30 mm, which is capable of preventing or suppressing the passage of microwaves. Therefore, in the lower space A irradiated with the microwaves, the microwaves are repeatedly reflected in front of the first gap 43A.

[0059] In a region of the lower space A where the first gap 43A is formed, the microwaves pass through the first gap 43A and enter the upper space B. Moreover, the microwaves traveling toward the portions of the rear wall 16 and the pair of side walls 15 that define the first gap 43A are reflected by the rear wall 16 and the side walls 15, respectively, and enter the upper space B through the first gap 43A. In the upper space B, the microwaves are repeatedly reflected by the top wall 14, the pair of side walls 15, and the upper plate 40 until they are incident on the top surface of the food placed on the upper plate 40.

[0060] The distance S2 (see FIG. 5) of the second gap 43B between the door 20 and the upper plate 40 is 0 mm or more and less than 30 mm, which is capable of preventing or suppressing the passage of microwaves. Therefore, the microwaves in the lower space A are prevented or suppressed from entering the upper space B through the second gap 43B. Even if the glass window 22 has a reflective layer 25, it is difficult to completely eliminate the leakage of microwaves from the window 22. However, since the passage of microwaves is prevented or suppressed in the second gap 43B, the leakage of microwaves from the window 22 can be minimized.

[0061] As described above, in this embodiment, most of the microwaves irradiated by the magnetron 30 can be guided through the first gap 43A into the upper space B and incident on the food to be cooked. Therefore, the food to be cooked can be efficiently heated because the microwaves can be efficiently irradiated to the food to be cooked.

[0062] In the case of the composite heating course, heater heating is performed following the microwave heating described above. Specifically, the control unit 33 stops the microwave irradiation by the magnetron 30, and then drives the heater 31 to heat the food by radiant heat. This allows the center of the food to be heated, and then the top surface of the food to be quickly browned.

[0063] In the heater heating course, there are cases where only the upper plate 40 is used, cases where only the lower plate 45 is used, and cases where both the upper plate 40 and the lower plate 45 are used. The upper plate 40 and the lower plate 45 arranged in the heating chamber 12 are at different distances from the heater 31, and therefore the amount of heat generated by the heater 31 is also different. Therefore, by using either the upper plate 40 or the lower plate 45, ideal heating according to the food to be cooked can be performed. Also, by using both the upper plate 40 and the lower plate 45, two different cooking methods can be performed at once.

[0064] Microwave oven 1 configured in this manner has the following features.

[0065] All of the walls 13 to 16 that define the heating chamber 12 are made of microwave reflectors, and a first gap (microwave passing portion) 43A is provided on the rear wall 16 side of the upper plate 40. Therefore, the microwaves irradiated by the magnetron 30 toward the rear wall 16 side are all reflected by the rear wall 16 and the pair of side walls 15, pass through the first gap 43A, and flow around to the upper side of the upper plate 40 without any leakage. After that, the microwaves are further reflected by the top wall 14 and irradiated to the upper side of the food placed on the upper plate 40. This makes it possible to heat the food efficiently.

[0066] Since the dimension S1 of the first gap 43A in the front-rear direction is 30 mm or more, microwaves can be reliably guided to the upper side of the upper plate 40 through the first gap 43A.

[0067] Since the microwave passing portion consists of the first gap portion 43A provided between the upper plate 40 and the rear wall 16 of the heating chamber 12, microwaves heading toward the rear wall 16 can be reliably passed to the upper side of the upper plate 40.

[0068] Since the rearward movement of the upper plate 40 is restricted by the stopper 36, a first gap 43A through which microwaves can pass can be secured between the rear wall 16 and the upper plate 40.

[0069] When microwaves are made to go around between the door 20 and the upper plate 40, they pass near the glass window 22 through which microwaves can pass, and are therefore likely to be attenuated. In contrast, in this embodiment, the gap S2 between the door 20 and the upper plate 40 is set to 0 mm or more and less than 30 mm, which is capable of preventing or suppressing the passage of microwaves, and therefore most of the microwaves irradiated by the magnetron 30 can go around to the upper side of the upper plate 40 through the first gap 43A on the rear end side of the upper plate 40. Therefore, the microwaves can be efficiently irradiated to the food, and the food can be heated efficiently.

[0070] Since the heater 31 is provided above the upper plate 40, the top surface of the food to be cooked can be quickly browned.

[0071] Since the upper plate 40 is made of metal, microwaves can be guided through the first gap 43 to the upper side of the upper plate 40 without leaking, and the food can be efficiently heated. The metal upper plate 40 can also be used for heating. This eliminates the need to change plates depending on the heating course for the food, improving user convenience.

[0072] Since the upper plate 40 and the lower plate 45 are at different distances from the heater 31, the amount of heat generated by the heater 31 also differs. Therefore, by selectively using the upper plate 40 or the lower plate 45 depending on the food to be cooked, ideal heating according to the food can be performed.

[0073] It is equipped with a control unit 33 that automatically switches between microwave heating by the magnetron 30 and heater heating by the heater 31. Therefore, it is possible to perform ideal heating depending on the food to be cooked, such as cooking the center of the food by microwave heating and quickly browning the surface of the food by heater heating.

[0074] Second embodiment 10 shows microwave oven 1 of the second embodiment. Microwave oven 1 differs from the first embodiment in that recess 16b is provided in rear wall 16 of heating chamber 12 to provide first gap 43A.

[0075] The recess 16b includes an upper plate 16c, a lower plate 16d, and a pair of side plate portions 16e each connected to the rear wall main body 16a, and end plate portions 16f connected to the rear ends of the upper plate 16c, the lower plate 16d, and the pair of side plate portions 16e.

[0076] The upper plate portion 16c is a flat plate inclined downward from the front to the rear in the front-rear direction X, and is located above the upper plate 40 in the attached state as a whole. The lower plate portion 16d is a flat plate inclined upward from the front to the rear in the front-rear direction X, and is located below the upper plate 40 in the attached state as a whole. The pair of side plate portions 16e are connected to the side ends of the upper plate portion 16c and the lower plate portion 16d, respectively, and are located outside in the width direction Y of the upper plate 40 in the attached state as a whole.

[0077] The end plate portion 16f extends along the YZ plane so as to be parallel to the rear wall main body 16a. A first gap 43A is formed between the end plate portion 16f and the rear end of the upper plate 40, and the distance S1 of the first gap 43A in the front-rear direction is set to 8 mm or more. The position where the stopper 36 is formed is set based on the end plate portion 16f.

[0078] The second embodiment thus configured can achieve the same actions and effects as the first embodiment. In addition, in the second embodiment, a part of the first gap 43A is formed by a recess 16b provided in the rear wall 16 so as to be recessed rearward. Therefore, the first gap 43A through which microwaves can pass can be secured between the rear wall 16 and the upper plate 40. In addition, it is not necessary to make the upper plate 40 excessively small in order to secure the first gap 43A. Therefore, a sufficient space can be secured for arranging the food to be cooked.

[0079] It should be noted that microwave oven 1 of the present invention is not limited to the configuration of the above embodiment, and various modifications are possible.

[0080] For example, as shown in FIG. 11, the upper plate 40 may be disposed at the center of the heating chamber 12 in the front-rear direction, and a second gap 43B may be provided between the upper plate 40 and the door 20 with a distance S2 of 30 mm or more.

[0081] In a second embodiment shown in FIG. 10, the dimension D1 of the upper plate 40 may be set to be the same as the dimension D2 (see FIG. 5) of the lower plate 45, and the entire first gap 43A may be formed by the recess 16b.

[0082] As shown in FIG. 12, the first gap (microwave passing portion) 43A may be formed by a notch 40a formed on the rear wall 16 side of the upper plate 40 itself. In the example of FIG. 12, the notch 40a is rectangular, but may be arcuate, and the shape can be changed as necessary. The dimension w in the width direction Y of the notch 40a is 30 mm or more through which the microwaves irradiated by the magnetron 30 can pass without being reduced, and there is no upper limit. The dimension D1 in the front-rear direction X of the upper plate 40 is set so that gaps of 0 mm or more and less than 30 mm that can prevent or suppress the passage of the microwaves irradiated by the magnetron 30 are formed between the rear end of the upper plate 40 and the rear wall 16 of the heating chamber 12, and between the front end of the upper plate 40 and the door 20. In this way, the same action and effect as in the above embodiment can be obtained, and the configuration can be simplified because the stopper 36 of the upper guide rail 35 is not necessary.

[0083] The first gap (microwave passing portion) 43A may be formed by a punched portion instead of the notch 40a shown in Fig. 12. The punched portion is provided forward of the rear end of the upper plate 40. However, the punched portion is provided closer to the rear end (rear wall 16) than the center of the upper plate 40 in the front-rear direction X. In addition, the distance between opposing edges of the punched portion is set to 30 mm or more, which allows microwaves to pass through without being attenuated.

[0084] As shown in FIG. 13, the upper plate 40 may be configured to include a metal plate body 41 arranged on the door 20 side and a molded part 44 made of resin (microwave-transmitting body) arranged on the rear wall 16 side, and the molded part 44 may constitute a microwave passing part. Such an upper plate 40 can be manufactured by insert molding. The dimension D1 in the front-rear direction X of the upper plate 40, that is, the dimension from the front end of the plate body 41 to the rear end of the molded part 44, is set to a length that forms a gap between the upper plate 40 and the rear wall 16 of the heating chamber 12 and between the upper plate 40 and the door 20, which is 0 mm or more and less than 30 mm. Even in this case, the same action and effect as in the above embodiment can be obtained, and the stopper 36 of the upper guide rail 35 is not necessary, so that the configuration can be simplified.

[0085] The molded portion 44 shown in Fig. 13 may be provided separately from the upper plate 40. Also, a molded part made of resin (a so-called spacer) may be disposed in the first gap portion 43A shown in Fig. 6. Even in this case, the same action and effect as in the above embodiment can be obtained, and the stopper 36 of the upper guide rail 35 is not required, so that the configuration can be simplified.

[0086] It is also possible to dispose only the upper plate 40 without providing the lower guide rail 38. It is also possible to dispose only the microwave heating without providing the heater 31.

[0087] The microwaves irradiated by the magnetron 30 may be able to pass through a first gap 46A between the rear end of a lower plate 45 disposed on the lower guide rail 38 and the rear wall 16 of the heating chamber 12. In other words, the dimension (spacing S3) of the first gap 46A in the front-rear direction X may be set to a distance that actively allows the microwaves irradiated by the magnetron 30 to pass through. [Explanation of symbols]

[0088] 1. Microwave 10 Microwave oven body 11. Cabinet 12 Heating chamber 13 Bottom wall 14 Ceiling Wall 15 Side wall 16 Back wall 16a Back wall body 16b Recess 16c Upper plate 16d Lower plate part 16e Side plate part 16f End plate part 17 Aperture 18 Power supply port 20 Door 21 Frame 22 Window 23 Inner Window 24 Exterior window 25 Reflective layer 30 Magnetron 30a Duct 31 Heater 33 Control Unit 35 Upper guide rail 36 Stopper 38 Lower guide rail 40 Upper Plate 40a Notch 41 Plate body 41a Bottom wall 41b Outer wall 41c curl section 42 Insulating cover 42a Bottom cover part 42b Side cover part 42c Upper cover part 43A First gap (microwave passage section) 43B 2nd cavity 44 Molding section (microwave passing section) 45 Lower Plate 46A 1st cavity 46B 2nd cavity

Claims

1. a microwave oven body having a heating chamber defined by a bottom wall, a top wall, a pair of side walls and a rear wall, each of the walls being made of a microwave reflector, and a magnetron for heating food within the heating chamber; a door attached to the microwave oven body in an openable and closable manner to close a front opening of the heating chamber; A pair of guide rails are provided on the pair of side walls, respectively, so as to extend in the front-rear direction; A plate that is detachably disposed on the pair of guide rails and on which the food is placed; a heater disposed above the plate; Equipped with The microwave generated by the magnetron is irradiated between the bottom wall and the plate of the heating chamber, a microwave passing portion through which the microwaves irradiated by the magnetron can pass is provided on the rear wall side of the plate disposed on the guide rail; and a pair of lower guide rails provided below the guide rails of the pair of side walls so as to extend in the front-rear direction, a lower plate that is detachably disposed on the pair of lower guide rails and has a dimension in the front-rear direction longer than a dimension in the front-rear direction of the plate; Equipped with a microwave oven.

2. 2. The microwave oven of claim 1, wherein the plate is made of metal.

3. 3. The microwave oven according to claim 1, wherein the microwave passing portion has a dimension of 30 mm or more in a front-to-rear direction.

4. 4. The microwave oven according to claim 1, wherein the microwave passing portion comprises a gap provided between the plate and the rear wall of the heating chamber.

Images