JP2010223437A - Microwave oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave oven allowing areas of base metals to be reduced while keeping the strength. <P>SOLUTION: The microwave oven 1 includes a seat part 110, the outer base metal 210, the inner base metal 220, and a transformer 200. The transformer 200 is placed on the seat part 110 via the outer base metal 210 and the inner base metal 220. The outer base metal 210 is fixed to the seat part 110 by screws at a first fixing position 311 and at a second fixing position 312, and the inner base metal 220 is fixed to the seat part 110 by screws at a third fixing position 313 and at a fourth fixing position 314. The transformer 200 is fixed by welding to the outer base metal 210 at a first welding position 321 and at a second welding position 322, and is fixed by welding to the inner base metal 220 at a third welding position 323 and at a fourth welding position 324. A first fixing line 331 is almost a straight line and is positioned on a peripheral wall surface side of a casing 10 in a flat surface area of the outer base metal 210. A second fixing line 332 is almost a straight line and is positioned on a peripheral wall surface side of the casing 10 in a flat surface area of the inner base metal 220. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention generally relates to a microwave oven, and more particularly to a microwave oven including a transformer.

  2. Description of the Related Art Conventionally, some microwave ovens for cooking an object to be cooked with microwaves include a transformer that is a high-voltage transformer for generating a high voltage for driving a magnetron that generates microwaves.

  For example, Japanese Unexamined Patent Publication No. 2001-76944 (Patent Document 1) describes a transformer for a microwave oven. In this transformer for microwave oven, the end surface of the laminated steel plate constituting the iron core, which is a structural material, is spot-welded (spot welded) to a bracket (foot metal), and is mounted in the device room of the microwave oven. In this microwave oven, the legs are formed in a single plate shape. The transformer is attached to the microwave oven by fixing a single sheet metal to the bottom plate of the microwave oven. The foot metal is formed larger than the bottom surface of the transformer so as to cover the entire bottom surface of the transformer from below, and is fixed by screwing at a portion protruding from the bottom surface of the transformer of the foot metal.

  In this way, by attaching the transformer tightly to the microwave oven via a single foot covering the entire bottom surface of the transformer, it is possible to firmly fix the heavy transformer and increase the attachment strength to the microwave oven. it can. For example, among the microwave oven drop test conditions, the most severe condition for installing a transformer is a test where the microwave oven is dropped from a predetermined height onto the floor surface in the upside down state with the bottom of the microwave oven facing up. is there. Even when the drop test is performed in this upside down state, the strength of spot welding between the end face of the laminated steel plate and the foot of the transformer has a safety factor several times that of the impact stress from the drop test. Therefore, peeling of the welded portion is almost prevented. Moreover, the screw which fastens and fixes the foot metal has a safety factor several times as large as the impact stress by the drop test. Therefore, as long as the base metal is not deformed due to the impact stress due to the drop test, the transformer does not easily float or come off from the bottom plate of the microwave oven.

JP 2001-76944 A

  However, in order to attach a transformer to a microwave oven via a single bracket (bracket) as in the microwave oven described in JP 2001-76944 A (Patent Document 1), the entire bottom surface of the transformer is You will need a large-sized cover. Since the amount of metal to be used for the metal plate increases as the metal plate increases, the production cost of the metal plate and the production cost of the entire microwave oven including the metal plate increase.

  Prices of metal materials that make up microwave ovens, such as steel plates and copper wires, vary depending on global market conditions. For this reason, it is conceivable to reduce the amount of materials used for the footing as part of design improvements to reduce the impact of soaring material prices on product costs and to supply products to the market at a stable price. In order to reduce the amount of the material used for the legs, it is conceivable to reduce the thickness of the legs or reduce the area of the legs. However, for example, even if the thickness of a 1.6 mm cold-rolled steel plate is reduced, it is possible to reduce the thickness of a metal plate that has already been made as thin as possible through trial manufacture confirmation to, for example, 1.4 mm. It is difficult without confirming the prototype. Moreover, even if such a thin plate is used, the price per weight of the steel plate becomes rather expensive as the thickness of the steel plate becomes thin. Therefore, it is not possible to greatly reduce the production cost of the foot plate by thinning the plate. .

  On the other hand, if the viewpoint can be changed to reduce the area of the metal rather than the thickness of the metal, the material cost of the metal can be reduced almost in proportion to the reduced area. However, if the portion that greatly contributes to the mounting strength of the transformer is removed when the area of the foot is reduced, the mounting strength of the transformer may not be maintained.

  In the past, metal materials prices have been stable at relatively low prices for a long period of time. No attempt was made to do so. It has been a design principle for those skilled in the art to focus on the risk of reducing the mounting strength of the transformer rather than reducing the material cost, and to use a single foot.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a microwave oven that can reduce the area of the metal plate while maintaining the mounting strength of the transformer.

  A microwave oven according to the present invention includes a casing having a peripheral wall surface, a heating chamber, a pedestal portion, an outer metal plate, an inner metal plate, and a substantially rectangular parallelepiped transformer.

  The heating chamber is formed inside the housing. The pedestal portion is disposed between the peripheral wall surface of the housing and the heating chamber. On the pedestal portion, the outer metal plate is fixed to the side relatively close to the peripheral wall surface of the housing, and the inner metal plate is fixed to the side relatively close to the heating chamber. The transformer has an outer end portion that is relatively close to the peripheral wall surface of the housing and an inner end portion that is relatively close to the heating chamber, and is placed on the pedestal portion via the outer and inner feet. Is done.

  The pedestal portion has a protruding portion protruding toward the heating chamber from the inner end portion of the transformer, and a bag portion is formed in the protruding portion.

  At least a part of the end portion of the inner foot on the heating chamber side is inserted and held in the bag portion.

  The outer end portion of the transformer protrudes closer to the peripheral wall surface than the end portion on the peripheral wall surface side of the casing of the pedestal portion.

  The microwave oven according to the present invention is a microwave oven configured as described above, and the outer metal is attached to the pedestal portion with screws at the first and second fixed positions arranged at a distance from each other. Fixed. The inner metal plate is fixed to the pedestal portion with screws at the third and fourth fixing positions that are spaced apart from each other.

  The transformer is fixed to the outer metal by welding at first and second welding positions that are spaced apart from each other, and at third and fourth welding positions that are spaced apart from each other. It is fixed to the inner metal plate by welding.

  The first fixing line connecting the first fixing position, the first welding position, the second welding position, and the second fixing position is a substantially straight line, and the circumference of the housing is within the plane region of the outer metal plate. Located on the wall side.

  The second fixing line connecting the third fixing position, the third welding position, the fourth welding position, and the fourth fixing position is substantially a straight line, and the circumference of the housing is within the plane area of the inner metal plate. Located on the wall side.

  In this way, the transformer is fixed to the outer metal by welding at the first and second welding positions that are spaced apart from each other, and the third and fourth that are spaced apart from each other. Since it is fixed to the inner metal plate by welding at the welding position, the transformer is fixed to the two metal plates of the outer metal plate and the inner metal plate by welding.

  On the other hand, the outer metal plate is fixed to the pedestal portion with screws at first and second fixing positions that are spaced apart from each other, and the inner metal foot is third and third that are spaced apart from each other. Since it is fixed to the pedestal portion with screws at the fixed position 4, the transformer is placed on the pedestal portion via the outer and inner legs.

  At this time, the first fixing line connecting the first fixing position, the first welding position, the second welding position, and the second fixing position is substantially a straight line, and the housing is within the plane region of the outer metal plate. Since it is located on the peripheral wall surface side of the body, the distance from the first fixed position to the second fixed position through the first welding position and the second welding position can be minimized.

  By shortening the distance from the first fixing position to the second fixing position through the first welding position and the second welding position, the outer metal plate and the base portion are fixed by screws. It is difficult for the outer metal to be deformed between the first and second fixing positions and the first and second welding positions where the outer metal and the transformer are fixed by welding.

  In addition, the second fixing line connecting the third fixing position, the third welding position, the fourth welding position, and the fourth fixing position is substantially a straight line, and the housing is formed within the plane region of the inner metal plate. Therefore, the distance from the third fixing position to the fourth fixing position through the third welding position and the fourth welding position can be minimized.

  By shortening the distance from the third fixing position to the fourth fixing position through the third welding position and the fourth welding position, the inner foot metal and the pedestal are fixed by screws. It is difficult for the inner metal plate to deform between the third and fourth fixing positions and the third and fourth welding positions where the inner metal plate and the transformer are fixed by welding.

  In this way, the outer and inner legs are less likely to be deformed, so the transformer is placed on the pedestal portion via two separately formed outer and inner legs. can do. Therefore, it is not necessary to use a single large foot having an area covering the entire bottom surface of the transformer.

  By doing so, it is possible to provide a microwave oven capable of reducing the area of the foot metal while maintaining the mounting strength of the transformer.

  Further, the pedestal portion has a protruding portion protruding toward the heating chamber from the inner end portion of the transformer, and a bag portion is formed in the protruding portion. By inserting and holding at least a part of the end portion on the heating chamber side of the inner metal plate, the inner metal plate can be easily fixed.

  Further, since the outer end portion of the transformer protrudes toward the peripheral wall surface rather than the end portion on the peripheral wall surface side of the housing of the pedestal portion, a space that can be used as a heating chamber in the housing can be increased. .

  In addition, by reducing the area of the base metal, vibrations accompanying the operation of the transformer are less likely to be transmitted to the housing, and noise accompanying the operation of the microwave oven can be reduced.

  In the microwave oven according to the present invention, the first fixed line is preferably located closer to the peripheral wall surface side of the housing than the center of gravity of the transformer.

  By doing so, the transformer can be made more stable.

  As described above, according to the present invention, it is possible to provide a microwave oven that can reduce the area of the metal plate while maintaining the mounting strength of the transformer.

1 is a perspective view showing an entire microwave oven as one embodiment of the present invention. It is a front view which shows typically the transformer arrange | positioned inside a microwave oven and the housing | casing of a microwave oven. It is a top view when a trans | transformer, an outer side metal plate, an inner side metal plate, and a base part are seen from upper direction. It is a bottom view when a transformer, an outer side metal, an inner side metal, and a pedestal part are seen from the lower part. It is a bottom view when the transformer with which a microwave oven is provided, a foot, and a base part are seen from the lower part for comparison.

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

  FIG. 1 is a perspective view showing the entirety of a microwave oven as one embodiment of the present invention.

  As shown in FIG. 1, the microwave oven 1 is entirely covered with the housing | casing 10 which has the surrounding wall surface of a substantially rectangular parallelepiped shape. A heating chamber is formed inside the housing 10. In addition, a transformer 200, a control unit, and the like are accommodated in the housing 10. An opening for communicating the inside of the heating chamber and the outside of the housing 10 is formed on the front surface of the housing 10. The opening is opened and closed by the door 20. A door screen 21 is formed on the door 20 so that the user can visually recognize the inside of the heating chamber. On the front surface of the housing 10, an output adjustment unit 31 that adjusts the output of the magnetron for cooking, a timer unit 32 that sets the cooking time, and a button 33 for starting and stopping the cooking are arranged. Has been. The user operates the output adjustment unit 31, the timer unit 32, and the button 33 to heat cook the object to be cooked.

  FIG. 2 is a front view schematically showing a transformer disposed inside the microwave oven and a housing of the microwave oven.

  As shown in FIG. 2, a heating chamber 40 is formed inside the housing 10 of the microwave oven 1. A pedestal 110 is formed on the bottom plate 100 of the casing 10 of the microwave oven 1. The pedestal portion 110 is formed between the peripheral wall surface of the housing 10 and the heating chamber 40 by projecting a part of the bottom plate 100 toward the inside upper side of the housing 10.

  On the pedestal portion 110, an outer metal plate 210 and an inner metal plate 220 are placed and fixed with screws. The outer metal plate 210 is disposed on the peripheral wall surface side of the housing 10 on the pedestal part 110. The inner side footing 220 is disposed on the heating chamber 40 side on the pedestal part 110. In this embodiment, the outer and inner legs 210 and 220 are formed to have a thickness of 1.6 mm, for example.

  A substantially rectangular parallelepiped transformer 200 is placed on the outer and inner metal legs 210 and 220. The transformer 200 is fixed by being welded to both the outer metal plate 210 and the inner metal plate 220. The substantially rectangular parallelepiped transformer 200 has an outer end 201 close to the peripheral wall surface side of the housing 10 and an inner end 202 close to the heating chamber 40.

  The pedestal portion 110 includes an end portion 111 on the peripheral wall surface side of the housing 10 and a protruding portion 112 that protrudes toward the heating chamber 40 from the inner end portion 202 of the transformer 200.

  FIG. 3 is a top view when the transformer, the outer metal plate, the inner metal plate, and the pedestal portion are viewed from above. FIG. 4 is a bottom view when the transformer, the outer metal plate, the inner metal plate, and the pedestal portion are viewed from below. In FIG. 4, the pedestal portion is indicated by a one-dot chain line.

  As shown in FIGS. 3 and 4, on the pedestal portion 110, an outer metal plate 210 and an inner metal plate 220 are arranged side by side with a space therebetween. The end portion 111 of the pedestal portion 110 is disposed on the peripheral wall surface side of the housing, and the protruding portion 112 is disposed on the heating chamber side.

  The protruding portion 112 of the pedestal portion 110 has bag portions 120 formed at two locations. Two corners of the inner metal foot 220 are inserted into the bag portion 120 so that the inner metal foot 220 is easily fixed.

  The transformer 200 is not evenly supported by the pedestal part 110. That is, the outer end 201 of the transformer 200 protrudes closer to the peripheral wall surface of the housing than the end 111 of the pedestal 110. Further, the inner end portion 202 of the transformer 200 is located closer to the peripheral wall surface side of the housing than the protruding portion 112 of the pedestal portion 110. That is, the center of gravity G of the transformer 200 does not overlap with the center P of the pedestal part 110 but is positioned closer to the peripheral wall surface side of the housing than the center P of the pedestal part 110. Thus, the volume of the heating chamber can be increased without enlarging the casing by bringing the transformer 200 closer to the peripheral wall surface side of the casing as compared with the pedestal portion 110.

  The outer foot metal 210 is fixed to the pedestal part 110 with a screw at a first fixing position 311 and a second fixing position 312 that are spaced apart from each other. The inner side foot 220 is fixed to the pedestal part 110 with a screw at a third fixing position 313 and a fourth fixing position 314 that are spaced apart from each other.

  On the other hand, the transformer 200 is fixed to the outer metal base 210 by welding, for example, spot welding, at a first welding position 321 and a second welding position 322 that are arranged with a space therebetween. In addition, the transformer 200 is fixed to the inner metal base 220 by welding, for example, spot welding, at a third welding position 323 and a fourth welding position 324 that are spaced apart from each other.

  A first fixing line 331 that connects the first fixing position 311, the first welding position 321, the second welding position 322, and the second fixing position 312 is substantially a straight line, and is a planar region of the outer metal plate 210. It is located on the peripheral wall surface side of the housing.

  A second fixing line 332 connecting the third fixing position 313, the third welding position 323, the fourth welding position 324, and the fourth fixing position 314 is substantially a straight line, and is a plane region of the inner metal plate 220. It is located on the peripheral wall surface side of the housing.

  In addition, the first fixed line 331 is located closer to the peripheral wall surface side of the housing 10 than the center of gravity G of the transformer 200.

  As described above, the first fixed position 311, the second fixed position 312, the third fixed position 313, and the fourth fixed position 314 are substantially spaced from the center P of the pedestal part 110 on the pedestal part 110. They are arranged in a balanced manner so that they are equal. On the other hand, the first welding position 321, the second welding position 322, the third welding position 323, and the fourth welding position 324 have the same distance from the center of gravity G of the transformer 200 on the bottom surface of the transformer 200. Is not arranged.

  The first fixed line 331 is located on the peripheral wall surface side of the housing in the plane area of the outer metal plate 210, and the second fixed line 332 is on the peripheral wall surface side of the housing in the flat area of the inner metal plate 220. Located in. For this reason, the outer metal plate 210 and the inner metal plate 220 are disposed asymmetrically across the center P of the pedestal part 110.

  For comparison, FIG. 5 is a bottom view of a transformer included in a microwave oven, a foot plate, and a pedestal portion as viewed from below. FIG. 5A is a diagram in the case where the entire metal plate is formed by a single plate, and FIG. 5B is a diagram in the case of having one metal plate of an outer metal plate and an inner metal plate. FIG.

  5A and 5B, the pedestal part 110 and the transformer 200 are formed in the same manner as the pedestal part 110 and the transformer 200 shown in FIGS. Further, in order to make the size of the heating chamber as large as possible in the casing, the transformer 200 is arranged in the casing 10 (FIG. 1) in the pedestal portion 110, similarly to the arrangement in the microwave oven 1 (FIGS. 1 and 2) of the present invention. FIG. 2) is arranged on the pedestal part 110 so as to protrude toward the peripheral wall surface side of the housing 10 from the end part 111 on the peripheral wall surface side in FIG.

  First, as shown in FIG. 5A, a case where the transformer 200 is attached to the pedestal portion 110 via a single foot 800 will be considered.

  The foot 800 is formed in a size that covers almost the entire bottom surface of the transformer 200. The foot 800 is disposed at substantially the center of the pedestal part 110. That is, the center Q of the foot 800 and the center P of the pedestal part 110 substantially overlap.

  The foot 800 is fixed to the pedestal 110 with screws at the first fixed position 811, the second fixed position 812, the third fixed position 813, and the fourth fixed position 814. The first fixed position 811, the second fixed position 812, the third fixed position 813, and the fourth fixed position 814 are spaced apart from each other at the four corners of the base metal 800 from the center Q of the base metal 800. Are arranged so that their distances are substantially equal. In addition, the first fixed position 811, the second fixed position 812, the third fixed position 813, and the fourth fixed position 814 are spaced apart from each other at the four corners of the pedestal part 110 at the center of the pedestal part 110. It arrange | positions so that the distance from P may be substantially equal.

  On the other hand, the transformer 200 is fixed to the base metal 800 by welding at the first welding position 821, the second welding position 822, the third welding position 823, and the fourth welding position 824. The first welding position 821, the second welding position 822, the third welding position 823, and the fourth welding position 824 are spaced apart from each other at four corners of the transformer 200 from the center of gravity G of the transformer 200. Are arranged to be approximately equal.

  In this way, when the transformer 200 is attached to the pedestal part 110 via the single foot 800, the transformer 200 has the first welding position 821, the second welding position 822, the third welding position 823, The fourth welding position 824 is supported on the foot 800 in a well-balanced manner. Also, the foot 800 on which the transformer 200 is placed is supported on the pedestal part 110 in a well-balanced manner by the first fixed position 811, the second fixed position 812, the third fixed position 813, and the fourth fixed position 814. Is done.

  Therefore, high strength can be obtained in the microwave oven including the transformer 200 attached to the pedestal part 110 in this manner. For example, when the inventors of the present application conducted a drop test in which the bottom surface of the microwave oven was dropped from a height of 70 cm above the floor onto the floor surface, the transformer 200 was detached from the pedestal 110, and the foot 800 was It turned out that it was hard to deform.

  However, the area of the single metal plate 800 is larger than the combined area of the outer metal plate 210 and the inner metal plate 220 shown in FIGS. 3 and 4. As described above, when the transformer 200 is attached to the pedestal part 110 via the single metal plate 800, the strength of the microwave oven can be increased, but on the other hand, the metal necessary for forming the metal plate 800 is required. The amount of increases.

  Next, as shown in FIG. 5B, a case where the transformer 200 is attached to the pedestal portion 110 via two outer and inner metal legs 901 and 902 will be considered.

  The outer metal plate 901 and the inner metal plate 902 are respectively formed in the same size as the outer metal plate 210 and the inner metal plate 220 shown in FIGS. 3 and 4 included in the microwave oven of the present invention. The outer metal plate 901 and the inner metal plate 902 are produced by cutting off a portion (excess portion) that is not welded or fixed with screws in the single metal plate 800 shown in FIG.

  The outer foot metal 901 is fixed to the pedestal part 110 with screws at the first fixing position 911 and the second fixing position 912. In addition, the inner metal foot 902 is fixed to the pedestal part 110 with screws at the third fixing position 913 and the fourth fixing position 914. The outer metal plate 901 and the inner metal plate 902 are arranged on the pedestal part 110 so as to be substantially symmetrical with the center P of the pedestal part 110 interposed therebetween. The first fixed position 911, the second fixed position 912, the third fixed position 913, and the fourth fixed position 914 are spaced from each other at four corners of the pedestal part 110 from the center P of the pedestal part 110. Are arranged so that their distances are substantially equal.

  On the other hand, the transformer 200 is fixed to the outer metal plate 901 by welding at the first welding position 921 and the second welding position 922. In addition, the transformer 200 is fixed to the inner metal base 902 by welding at the third welding position 923 and the fourth welding position 924. The first welding position 921, the second welding position 922, the third welding position 923, and the fourth welding position 924 are spaced apart from each other at four corners of the transformer 200 from the center G of the transformer 200. Are arranged to be approximately equal.

  In this way, when the transformer 200 is attached to the pedestal portion 110 via the two outer and inner metal legs 901 and 902, the transformer 200 has the first welding position 921, the second welding position 922, The third welding position 923 and the fourth welding position 924 are supported on the outer and inner metal legs 901 and 902 in a well-balanced manner. In addition, the outer and inner legs 901 and 902 on which the transformer 200 is placed are arranged on the pedestal portion 110 in a well-balanced manner, a first fixed position 911, a second fixed position 912, and a third fixed position. 913 is supported on the pedestal 110 at the fourth fixed position 914.

  As described above, the first fixed position 911, the second fixed position 912, the third fixed position 913, and the fourth fixed position 914 are arranged in a well-balanced manner on the pedestal portion 110, and the first fixed position 911, the second fixed position 913, and the fourth fixed position 914 are arranged on the transformer 200. 1 welding position 921, 2nd welding position 922, 3rd welding position 923, and 4th welding position 924 are arranged with good balance. In addition, the outer side metal 901 and the inner side metal 902 are arranged on the pedestal part 110 on the pedestal part 110 in a well-balanced and substantially symmetrical manner across the center P of the pedestal part 110.

  By doing so, the combined area of the outer and inner metal plates 901 and 902 becomes the same as the combined area of the outer and inner metal plates 210 and 220 shown in FIGS. The area can be made smaller than that of the single metal plate 800 shown in FIG.

  However, when the drop test of the microwave oven was performed, deformation was seen in the outer metal plate 901. As a drop test, a drop test was performed in which the product was dropped from a height of 70 cm above the floor surface onto the floor surface in an upside down state with the bottom of the microwave oven in the packaged state facing up. For the drop test, a microwave oven including a transformer 200 attached to the pedestal part 110 via two outer and inner metal legs 901 and 902 was used. When such a drop test was performed, deformation of the outer metal plate 901 was observed in a region 930 shown in FIG. The outer metal base 901 was deformed between the first fixed position 911 and the first welding position 921 and between the second fixed position 912 and the second welding position 922.

  In addition, since two corner | angular parts were inserted in the bag part 120 of the base part 110, the deformation | transformation was not looked at by the inner side buckle 902.

  In this way, the amount of metal used for the metal plate can be reduced only by cutting off the surplus portion of the single metal plate 800 (FIG. 5A), but the outer metal plate in the drop test can be reduced. It has been found that the strength of attachment to the microwave oven cannot be maintained because 901 is deformed and the transformer 200 is lifted.

  The present inventors conducted a drop test under various conditions, and analyzed and examined the stress applied to the transformer legs, that is, the outer and inner legs 901 and 902 under each condition. As a result, it has been clarified that stresses applied to the outer and inner metal plates 901 and 902 do not cause problems such as deformation of the metal plate under conditions other than the upside down state.

  Therefore, the inventors of the present application narrowed down the subject of investigation to the fact that the outer metal plate 901 would be deformed in the drop test in the upside down state, and conducted various studies.

  By the way, when the transformer 200 is arranged in the casing of the microwave oven, there are restrictions on the arrangement of the transformer 200, the outer metal plate 901, the inner metal plate 902, and the pedestal part 110.

  First, restrictions on the position where the transformer 200 is arranged will be described.

  In the microwave oven, it is necessary to maximize the volume of the heating chamber without enlarging the casing. Therefore, there is a restriction that the transformer 200 must be moved as close as possible to the peripheral wall surface side of the housing.

  Next, restrictions on the position at which the outer metal base 901 is fixed on the pedestal 110 will be described.

  The outer foot metal 901 is fixed on the pedestal 110 with screws. The pedestal part 110 is disposed between the peripheral wall surface of the casing and the heating chamber inside the casing. In this embodiment, the pedestal part 110 is formed by projecting a part of the bottom plate of the casing upward inside the casing. When the pedestal part 110 is formed in this way, there is a gap between the peripheral wall surface of the casing and the end part 111 of the pedestal part 110.

  The outer metal foot 901 is fixed on the pedestal 110 with screws. Even if the first fixing position 911 and the second fixing position 912 that fix the outer metal base 901 and the pedestal part 110 are arranged on the most peripheral wall surface side of the housing, the end face of the pedestal part 110 111 position. As described above, a gap is provided between the end surface 111 of the pedestal portion 110 and the peripheral wall surface of the housing. Therefore, there is a restriction that the first fixing position 911 and the second fixing position 912 that fix the outer metal plate 901 and the pedestal part 110 are arranged at a distance from the peripheral wall surface of the housing.

  Next, a description will be given of the restriction on the position at which the inner metal plate 902 is fixed on the pedestal portion 110.

  The inner metal plate 902 is fixed on the pedestal part 110 with a screw in the same manner as the outer metal plate 901. Further, the inner metal foot 902 is held by inserting two corners on the heating chamber side into the bag portion 120 of the pedestal portion 110.

  In order to form the bag portion 120 for holding the corner portion of the inner metal base 902 on the heating chamber side, the end portion on the heating chamber side of the pedestal portion 110 is closer to the heating chamber side than the inner end portion 202 of the transformer 200. A projecting portion 112 projecting into the surface is formed. Since the corner of the inner metal foot 902 is inserted into the bag portion 120 formed in the protruding portion 112, the end portion of the inner foot metal 902 on the heating chamber side is also closer to the heating chamber side than the inner end portion 202 of the transformer 200. It arrange | positions so that it may protrude. As described above, the heating chamber side end of the pedestal portion 110 and the inner chamber 902 end on the heating chamber side have a restriction that the inner end portion 202 of the transformer 200 protrudes to the heating chamber side.

  In summary, the transformer 200 is arranged with the outer end portion 201 as close as possible to the peripheral wall surface of the housing, and the end portion 111 of the pedestal portion 110 and the end portion of the outer metal plate 901 on the peripheral wall side are arranged on the housing. It is arranged with a space between the peripheral wall surface, and the heating chamber side ends of the pedestal part 110 and the inner metal foot 902 are arranged so as to protrude from the inner end 202 of the transformer 200 to the heating chamber side. There are limitations. Under these constraints, the transformer 200 cannot be placed on the pedestal portion 110 in a well-balanced manner so that the center of gravity G of the transformer 200 is directly above the center P of the pedestal portion 110. In addition, the transformer 200 cannot be evenly supported by the two outer metal plates 901 and the inner metal plates 902. That is, the center of gravity G of the transformer 200 is arranged more biased toward the peripheral wall surface side of the housing than the center P of the pedestal part 110, the outer and inner metal legs 901 and 902 fixed on the pedestal part 110, and the center of gravity. Is done.

  The inventors of the present application, under these constraints, the arrangement of the outer and inner legs, the arrangement of the fixed positions for fixing the outer and inner legs to the pedestal with screws, Various studies were made on the arrangement of the welding position where the inner metal plate and the transformer are fixed by welding. As a result, the outer metal plate 901 is deformed in the drop test only by cutting off the surplus portion of one metal plate 800 (FIG. 5A). It was found that the line connecting the welding position 921, the second welding position 922, and the second fixing position 912 is not a straight line.

  Therefore, based on the knowledge of the inventors, in the microwave oven 1 according to one embodiment of the present invention, the first fixed position 311, the first welding position 321, the second welding position 322, and the second The first fixing line 331 connecting the fixing position 312 is substantially a straight line, and is located on the peripheral wall surface side of the housing 10 in the plane area of the outer metal plate 210. Further, the second fixing line 332 connecting the third fixing position 313, the third welding position 323, the fourth welding position 324, and the fourth fixing position 314 is substantially a straight line, It is located on the peripheral wall surface side of the housing 10 in the plane area.

  In this way, the transformer 200 is fixed to the outer metal base 210 by welding at the first welding position 321 and the second welding position 322 that are spaced apart from each other, and is disposed at a distance from each other. Since the third welding position 323 and the fourth welding position 324 are fixed to the inner metal plate 220 by welding, the transformer 200 is fixed to the two metal plates of the outer metal plate 210 and the inner metal plate 220 by welding. Is done.

  On the other hand, the outer metal plate 210 is fixed to the pedestal part 110 with screws at the first fixed position 311 and the second fixed position 312 that are arranged with a space therebetween, and the inner metal plate 220 is spaced from each other. Since the transformer 200 is fixed to the pedestal part 110 with screws at the third fixed position 313 and the fourth fixed position 314 arranged in the above manner, the transformer 200 is mounted on the pedestal part 110 via the outer and inner metal legs 210 and 220. Placed on.

  At this time, the first fixing line 331 that connects the first fixing position 311, the first welding position 321, the second welding position 322, and the second fixing position 312 is substantially a straight line, and the outer metal foot 210. In this plane area, it is located on the peripheral wall surface side of the housing 10, so that the first fixing position 311 is connected to the second fixing position 312 through the first welding position 321 and the second welding position 322. The distance can be minimized.

  By shortening the distance from the first fixed position 311 to the second fixed position 312 through the first welding position 321 and the second welding position 322, Of the first fixing position 311 and the second fixing position 312 fixed by screws, and the first welding position 321 and the second welding position 322 where the outer metal plate 210 and the transformer 200 are fixed by welding. In the meantime, it becomes difficult for the outer side footing 210 to be deformed.

  Further, the second fixing line 332 connecting the third fixing position 313, the third welding position 323, the fourth welding position 324, and the fourth fixing position 314 is substantially a straight line, Since it is located on the peripheral wall surface side of the housing 10 in the plane area, it is a distance connecting the third fixing position 313 to the fourth fixing position 314 through the third welding position 323 and the fourth welding position 324. Can be minimized.

  By shortening the distance from the third fixing position 313 to the fourth fixing position 314 through the third welding position 323 and the fourth welding position 324, Of the third fixing position 313 and the fourth fixing position 314 to which the inner metal plate 220 and the transformer 200 are fixed by welding. In the meantime, it becomes difficult to deform | transform the inner side footing 220.

  In this way, the outer and inner metal plates 210 and 220 are not easily deformed. Therefore, the transformer 200 is mounted on the pedestal portion via two separately formed outer and inner metal plates 210 and 220. 110 can be mounted. Therefore, it is not necessary to use a single large foot having an area covering the entire bottom surface of the transformer 200.

  In this way, it is possible to provide the microwave oven 1 that can reduce the area of the metal plate while maintaining the mounting strength of the transformer.

  Further, the pedestal part 110 has a protruding part 112 that protrudes toward the heating chamber 40 from the inner end part 202 of the transformer 200, and a bag part 120 is formed in the protruding part 112. By inserting and holding at least a part of the end portion on the heating chamber 40 side of the inner leg 220, the inner leg 220 can be easily fixed.

  Further, the outer end portion 201 of the transformer 200 protrudes toward the peripheral wall surface side from the end portion 111 on the peripheral wall surface side of the casing 10 of the pedestal portion 110, so that it can be used as the heating chamber 40 in the casing 10. The space that can be made can be enlarged.

  In addition, by reducing the area of the base metal, vibrations associated with the operation of the transformer 200 are not easily transmitted to the housing 10, and noise associated with the operation of the microwave oven 1 can be reduced.

  In the microwave oven 1, the first fixed line 331 is located on the peripheral wall surface side of the housing 110 with respect to the center of gravity G of the transformer 200.

  By doing so, the transformer 200 is fixed with the first fixed line 331 and the second fixed line 332 sandwiching the center of gravity G of the transformer 200, so that the transformer 200 is more stably attached to the base 110. Can be attached.

  The inventors of the present application conducted a drop test on the microwave oven 1 by dropping the microwave oven 1 onto the floor surface from a height of 70 cm above the floor surface with the bottom surface of the microwave oven 1 facing upward. As shown in the figure, in the drop test of the microwave oven in which the transformer 200 is attached to the pedestal part 110 through the two outer metal plates 901 and the inner metal plate 902, the inner metal plate 902 is not deformed. No deformation of the foot metal 220 was observed. At the same time, no deformation was seen in either the outer or inner gold plate 210 or 220. Therefore, in this drop test, it was confirmed that the microwave oven 1 had a transformer mounting strength equivalent to or higher than that of a conventional microwave oven in which the transformer was mounted by a single foot 800. .

  As described above, under other test conditions, it has already been confirmed that the deformation of the foot metal does not occur prior to the improvement. Therefore, it can be said that the microwave oven 1 has confirmed that there is no problem in the strength of mounting the transformer in the normal use state as well as the drop test.

  As a first method of manufacturing a divided bracket used in the present invention, as a first method, a new mold is manufactured, and two sheets of an outer plate 210 and an inner plate 220 are formed from a steel plate material. Can be made. In this case, compared to the case where one piece of the metal base 800 shown in FIG. 5A is manufactured, the amount of use of the steel plate material can be reduced by almost 33%. Is big. However, in this case, since it is necessary to manufacture a new mold, it is necessary to record depreciation expenses, and the cost reduction effect is reduced depending on the number of production.

  As a second method, after following the process of manufacturing the metal base 800 using a conventional mold and press, a cutting process is added to remove the central portion from the outer shape of the metal base 800. Thus, two sheets of an outer metal plate 210 and an inner metal plate 220 can be manufactured. In this case, it is not necessary to consider depreciation costs because there is no need to produce a new mold or a new press machine. On the other hand, the cost reduction effect can be realized by selling the cut and removed portion as scrap scrap.

  Conventionally, since the scrap scrap sales price was stable at about 1/15 to 1/20 of the new material price, the cost reduction effect by the second method described above was fine. However, as a result of soaring metal materials in recent years, for example, in the market price of August-September 2008, a phenomenon has been seen in which the scrap sale price of scrap scraps rises relatively to 1/3 to 1/5 that of new materials. It was. Such fluctuations in market prices have greatly expanded the cost reduction effect of selling scrap scrap.

  In the following, the trial calculation is advanced by an example of approximate calculation. Conventionally, if a 100 mm square metal plate is manufactured from a 1.6 mm thick steel plate, the weight of the metal plate is approximately 125 g. On the other hand, in the embodiment of the present invention, for example, the weights of the outer metal plate 210 and the inner metal plate 220 are approximately 80 g in total. If the outer metal plate 210 and the inner metal plate 220 are manufactured by the second method described above, approximately 45 g of scrap scrap is generated. 45 g of steel is 36% of the 125 g of steel used for a conventional single foot. Here, assuming that the sale price of scrap materials is approximately 30% of the purchase price of new materials, 45 g of scrap scrap materials, which is 36% of the 125 g of footwear materials, are sold at a price of 30% of the purchase price of new materials. It can be seen that about 10% of the metal material cost can be recovered. That is, the cost can be reduced by about 10% without particularly investing in the mold.

  Therefore, after considering the production quantity, scrap scrap purchase price, etc., as a comprehensive judgment, a new mold is manufactured to manufacture the metal base by the first method, or the metal base is manufactured by the second method. It is possible to select whether or not a cutting process is added to manufacture the image.

  In household microwave ovens, middle and upper models have shifted to an inverter power supply system that boosts a high-frequency AC power supply using a switching power supply circuit, so that the high-voltage transformer is lighter and smaller, and the feet that are the subject of the present invention are abolished. . Therefore, the microwave oven employing the conventional magnetron high-voltage power supply circuit that is the subject of the present invention is mainly a popular price range model. In the popular price range model, as a result of cost reduction studies over many years, the cost of each part is condensed, and even a cost reduction of several percent is extremely difficult. Against this background, as in the present invention, the cost improvement effect that can be expected to reduce the component cost by 10% or more can be said to be a very significant effect.

  The embodiment disclosed above should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above embodiments but by the scope of claims, and includes all modifications and variations within the meaning and scope equivalent to the scope of claims.

  1: Microwave oven, 10: Housing, 40: Heating chamber, 110: Pedestal part, 112: Protruding part, 120: Bag part, 200: Transformer, 201: Outer end part, 202: Inner end part, 210: Outer foot Gold, 220: inner metal foot, 311: first fixing position, 312: second fixing position, 313: third fixing position, 314: fourth fixing position, 321: first welding position, 322: 2nd welding position, 323: 3rd welding position, 324: 4th welding position, 331: 1st fixed line, 332: 2nd fixed line.

Claims (2)

A housing having a peripheral wall surface;
A heating chamber formed inside the housing;
A pedestal disposed between the peripheral wall surface of the housing and the heating chamber;
On the pedestal portion, an outer metal foot that is relatively fixed to the side closer to the peripheral wall surface of the housing, and an inner metal foot that is relatively fixed to the side closer to the heating chamber,
An outer end relatively close to the peripheral wall surface of the housing and an inner end relatively close to the heating chamber; and on the pedestal via the outer and inner legs. A substantially rectangular parallelepiped transformer mounted;
The pedestal portion has a protruding portion protruding toward the heating chamber from the inner end portion of the transformer, and a bag portion is formed in the protruding portion.
At least a part of the end portion on the heating chamber side of the inner foot metal is inserted and held in the bag portion,
The outer end portion of the transformer is a microwave that protrudes toward the peripheral wall surface side from the end portion of the pedestal portion on the peripheral wall surface side of the housing,
The outer foot metal is fixed to the pedestal portion with screws at first and second fixing positions arranged at a distance from each other,
The inner metal foot is fixed to the pedestal portion with screws at third and fourth fixing positions arranged at a distance from each other;
The transformer is fixed to the outer metal base by welding at first and second welding positions that are spaced apart from each other, and third and fourth welding positions that are spaced apart from each other. Fixed to the inner metal by welding at
A first fixing line connecting the first fixing position, the first welding position, the second welding position, and the second fixing position is substantially a straight line, and is within a plane region of the outer metal foot. Located on the peripheral wall surface side of the housing,
A second fixing line connecting the third fixing position, the third welding position, the fourth welding position, and the fourth fixing position is substantially a straight line, and is within a plane region of the inner metal foot. A microwave oven located on the peripheral wall surface side of the housing.   The microwave oven according to claim 1, wherein the first fixed line is located closer to a peripheral wall surface of the housing than a center of gravity of the transformer.

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