Electromagnetic induction heating cooker

Abstract

To enable weight of a material-to-be-heated to be more accurately measured by eliminating an influence exerted on measurement by a connection part between a heating coil and an inverter substrate, in an electromagnetic induction heating cooker having a measuring function of measuring the weight of the material-to-be-heated.SOLUTION: An electromagnetic induction heating cooker according to the present invention comprises: a top plate 2 for being loaded with a material-to-be-heated; a heating unit 3 for heating the material-to-be-heated by supporting the top plate 2 from the downside; and a measuring unit 4 for measuring the weight of the material-to-be-heated by supporting the heating unit 3 from the downside. The heating unit 3 includes a heating coil 24 for generating an induction field on the upside of the top plate 2, an inverter substrate 25 for supplying a high-frequency current to the heating coil 24, and an enclosure 29 for housing and supporting the heating coil 24 and the inverter substrate 25.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic induction cooking appliance having a weighing function for measuring the weight of an object to be heated. [Background technology]

[0002] As shown in Patent Document 1, for example, an electromagnetic induction cooking appliance (hereinafter referred to as "cooker") comprises a top plate on which an object to be heated is placed, a heating coil disposed on the inner surface of the top plate, and an inverter board (high-frequency inverter) that supplies high-frequency current to the heating coil. When high-frequency current is supplied from the inverter board to the heating coil, an induction magnetic field is generated above the top plate, eddy currents flow in the cooking container on the top plate, and the Joule heat generated by the electrical resistance heats the cooking container and the object to be heated therein. The heating coil, including its end portion, i.e., the connection portion with the inverter board, is composed of a litz wire made by twisting together multiple wires. The litz wire is formed into a multi-stage overlap twist structure through primary twisting in which the wires are twisted together, secondary twisting in which the primarily twisted bundles are twisted together, and tertiary twisting in which the secondary twisted bundles are twisted together.

[0003] The electromagnetic induction cooking appliance according to the present invention is equipped with a weighing function for measuring the weight of an object to be heated. A cooking appliance equipped with such a weighing function is disclosed, for example, in Patent Document 2. The cooking appliance in Patent Document 2 is configured such that the top plate is displaced downward relative to the main body in proportion to the weight of the object to be heated placed on the top plate. The heating coil is supported on the underside of the top plate and moves up and down integrally with the top plate. The weight detection means includes a fixed electrode fixed to the inner bottom surface of the main body and a movable electrode facing the fixed electrode from above. When the top plate is displaced downward, the movable electrode is pressed down via a vertically elongated spindle, changing the distance between it and the fixed electrode and changing the electrostatic capacitance between the two electrodes. The weight of the object to be heated on the top plate can be detected based on this change in electrostatic capacitance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-321358 [Patent Document 2] Microfilm of Utility Model Application No. 59-149289 (Utility Model Application No. 61-63796) Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in the cooker of Patent Document 2, the heating coil is configured to move up and down integrally with the top plate. With this configuration, even when the top plate moves up and down, the distance between the heating coil and the object to be heated on the top plate remains constant, allowing the heating coil to consistently heat the object stably. Meanwhile, as described in Patent Document 1, the heating coil is often made of litz wire, and the higher the output of the heating coil, the thicker the litz wire used. Because such thick litz wire is difficult to bend, the end of the heating coil made of litz wire, i.e., the connection portion with the inverter board, acts as a resistance that impedes the up and down movement of the heating coil, and this resistance may cause errors in the measurement of the weight of the object to be heated.

[0006] An object of the present invention is to provide an electromagnetic induction cooking device that can more accurately measure the weight of an object to be heated by eliminating the influence of the connection between the heating coil and the inverter board. [Means for solving the problem]

[0007] The electromagnetic induction cooking appliance according to the present invention comprises a top plate 2 on which an object to be heated is placed, a heating unit 3 that supports the top plate 2 from below and heats the object to be heated, and a weighing unit 4 that supports the heating unit 3 from below and measures the weight of the object to be heated. The heating unit 3 is characterized by including a heating coil 24 that generates an induction magnetic field above the top plate 2, an inverter board 25 that supplies a high-frequency current to the heating coil 24, and a housing 29 that houses and supports the heating coil 24 and the inverter board 25.

[0008] The heating unit 3 is provided with a control unit 5 connected to it by a cable 6, and the control unit 5 is disposed below the measuring unit 4.

[0009] The measuring unit 4 is supported from below by a base member 8 that houses the control unit 5.

[0010] The heating unit 3 includes a partition wall 26 that separates the heating coil 24 and the inverter board 25 from each other above and below. The heating coil 24 is supported on the upper surface of the partition wall 26 via a spacer 64. A lower support piece 65 that supports the partition wall 26 and upper support pieces 45 and 46 that support the top plate 2 are provided on the upper part of the housing 29. [Effects of the Invention]

[0011] The electromagnetic induction cooking appliance according to the present invention comprises a top plate 2 on which an object to be heated is placed, a heating unit 3 that supports the top plate 2 from below and heats the object to be heated, and a weighing unit 4 that supports the heating unit 3 from below and measures the weight of the object to be heated. In other words, the weighing unit 4 is subjected to the load of the heating unit 3 and the load of the top plate 2 including the object to be heated, and the top plate 2 and the heating unit 3 are configured to move up and down together in accordance with the weight of the object to be heated on the top plate 2.

[0012] In addition, in the present invention, heating unit 3 is configured to include heating coil 24 that generates an induction magnetic field above top plate 2, inverter board 25 that supplies high-frequency current to heating coil 24, and housing 29 that houses and supports heating coil 24 and inverter board 25. When heating coil 24 and inverter board 25 are integrated into heating unit 3 in this way, there is no relative displacement between them 24, 25. Therefore, even when heating coil 24 is made of a thick Litz wire, end portion 73 of heating coil 24, i.e., the connection portion with inverter board 25, does not interfere with the up and down movement of heating unit 3 including heating coil 24. In other words, according to the present invention, the influence of the connection portion between heating coil 24 and inverter board 25 can be eliminated, making it possible to more accurately measure the weight of an object to be heated placed on top plate 2.

[0013] By placing the control unit 5 below the weighing unit 4, a sufficient vertical distance can be secured between the heating unit 3 and the control unit 5, allowing the two units 3 and 5 to be loosely connected by a relatively long cable 6. This reduces the effect on the measured value of the weighing unit 4 of fluctuations in the tension of the cable 6 caused by the heating unit 3 moving up and down, thereby enabling more accurate measurement of the weight of the object to be heated.

[0014] By providing a base member 8 that supports the weighing unit 4 from below and houses the control unit 5, the weighing unit 4 can be prevented from being placed directly on the control unit 5, thereby preventing the weight of the weighing unit 4 from being applied to the control unit 5.

[0015] By providing a partition wall 26 that separates the heating coil 24 and the inverter board 25 from each other above and below, room-temperature air that has not been heated by heat exchange can be supplied to each of the heating coil 24 and the inverter board 25, thereby accurately air-cooling both the heating coil 24 and the inverter board 25. Furthermore, by providing a lower support piece 65 that supports the partition wall 26 and upper support pieces 45 and 46 that support the top plate 2 at the top of the housing 29 and supporting both the partition wall 26 and the top plate 2 by the housing 29, the heating coil 24 on the partition wall 26 can be easily and accurately positioned in the vertical direction relative to the top plate 2. By accurately positioning the heating coil 24 relative to the top plate 2, the distance from the heating coil 24 to the object to be heated on the top plate 2 can be optimized, allowing the object to be stably heated. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a front view of an internal structure of an electromagnetic induction heating cooker according to an embodiment of the present invention. [Figure 2] FIG. 1 is a perspective view of an electromagnetic induction heating cooker. [Figure 3] FIG. 2 is a vertical sectional front view of the upper part of the electromagnetic induction cooking appliance. [Figure 4] FIG. 2 is a vertical cross-sectional side view of the upper part of the electromagnetic induction cooking appliance. DETAILED DESCRIPTION OF THE INVENTION

[0017] (Embodiment) Figures 1 to 4 show an embodiment of an electromagnetic induction heating cooker (hereinafter referred to as "cooker" where appropriate) according to the present invention. In this embodiment, front, back, left, right, and top and bottom refer to the crossed arrows shown in Figure 2 and the indications of front, back, left, right, and top and bottom written near each arrow. As shown in Figures 1 and 2, the cooker comprises a rectangular frame-shaped casing 1 having an opening on its top surface, and a top plate 2 arranged to close the opening from above, and a cooking container P such as a pot containing an object to be heated is placed on the top plate 2.

[0018] Casing 1 houses, from top to bottom, a heating unit 3 that heats the object to be heated (the object to be heated contained in cooking container P) placed on top plate 2, a weighing unit 4 that measures the weight of the object to be heated, and a control unit 5 that controls the entire cooker. Heating unit 3 is electrically connected to control unit 5 via cables 6 arranged on each side of it, and weighing unit 4 is also electrically connected to control unit 5 via a cable not shown. The top of casing 1 surrounds the weighing unit 4 and heating unit 3 on all four sides. Casing 1 is made of metal such as stainless steel and prevents leakage of magnetism and electromagnetic waves generated by heating unit 3.

[0019] The measuring unit 4 supports the entire heating unit 3 from below. The heating unit 3 also supports the entire top plate 2 from below. In addition, the casing 1 is not in contact with the top plate 2, heating unit 3, or measuring unit 4, so the weight of the top plate 2 and the like does not act on the casing 1. Therefore, the weights of the heating unit 3 and top plate 2 and the weight of the object to be heated (including the cooking container P) on the top plate 2 act on the measuring unit 4. Because the former weight (the weight of the heating unit 3 and top plate 2) is constant, the latter weight, i.e., the weight of the object to be heated, can be measured by subtracting the former weight from the measurement value of the measuring unit 4 in advance.

[0020] A base member 8 is provided at the bottom of the cooking appliance, serving as its foundation, and a casing 1, which is an exterior panel, is fixed to surround the base member 8 on all four sides (front, back, left, and right). The base member 8 includes a main body frame 9 formed in a C-channel shape with openings on the front, back, and top, and a pair of left and right support frames 10 fixed to the edges of the opening on the top of the main body frame 9. The control unit 5 is housed inside the main body frame 9, and the weighing unit 4 is supported by the support frames 10. The weighing unit 4 is composed of a base 11 supported by the support frames 10, a weighing machine 12 provided on the base 11, and a platform 13 placed on top of the weighing machine 12, and is located approximately in the center of the casing 1. The platform 13 is formed in the shape of a square box that opens downward, and surrounds the weighing machine 12 on all four sides.

[0021] As shown in FIG. 2, an operation unit 17 operated by a cook is provided on the outer surface of the front wall 16 of the casing 1. The operation unit 17 is composed of a touch panel 18, a rotary dial 19, and push buttons 20. The operation unit 17 is located at the top of the front wall 16, and the top of the operation unit 17 is inclined downward toward the front. A transparent, rectangular operation cover 21 is detachably attached to the upper end of the front wall 16. The operation cover 21 covers the operation unit 17 from above, protecting it from water that may boil over from the cooking container P on the top plate 2. A cook standing in front of the cooker can adjust the output of the heating coil 24 of the heating unit 3 by operating the operation unit 17 while viewing the entire operation unit 17 through the operation cover 21.

[0022] As shown in FIG. 3 , the heating unit 3 is composed of a horizontal, disk-shaped heating coil 24 facing the inner surface of the top plate 2, an inverter board 25 that supplies high-frequency current to the heating coil 24, a partition wall 26 that separates the heating coil 24 and the inverter board 25 from above and below, two temperature sensors 27 and 28 that detect the temperature of the cooking container P through the top plate 2, and a housing 29 that houses these components. The heating coil 24 is made of a litz wire, which is made by twisting together multiple strands of wire and winding it into a spiral shape. The litz wire is formed through a primary twisting process in which the strands are twisted together, and a secondary twisting process in which the primarily twisted strands are twisted together. When a high-frequency current is supplied to the heating coil 24 from the inverter board 25, an induced magnetic field is generated above the top plate 2, causing eddy currents to flow in the cooking container P on the top plate 2. The Joule heat generated by the electrical resistance heats the cooking container P and the food contained therein.

[0023] The top plate 2 on which the cooking container P is placed is composed of a rectangular top frame 32, a rectangular baking sheet 33 fitted inside the top frame 32, and a magnetic shield plate 34. The baking sheet 33 and the magnetic shield plate 34 are stacked one on top of the other in the order shown and are supported from below by a support flange 35 with an L-shaped cross section that protrudes from the inner peripheral edge of the top frame 32. The baking sheet 33 is made of heat-resistant glass, and its top surface is approximately flush with the top surface of the top frame 32. The magnetic shield plate 34 is made of a non-magnetic, conductive material such as aluminum or copper. A circular coil opening 36 is formed in its center, allowing the heating coil 24 to face the baking sheet 33. The diameter of the coil opening 36 is set slightly larger than the outer diameter of the heating coil 24. Covering walls 37 extend downward from the left, right, and rear ends of the top frame 32, covering the upper end of the casing 1 from the outside, and a gutter 38 running left and right is provided at the front end of the top frame 32 (see Figure 4). The gutter 38 is located above the operation cover 21 and catches water or the like that spills forward from the cooking vessel P before the operation cover 21 does.

[0024] As shown in FIG. 3 , the top plate 2 is supported by the upper end of a housing 29 of the heating unit 3. The housing 29 is made of a metal such as stainless steel and has a rectangular box shape with an opening on the top surface. The housing 29 is composed of a center case 41 that forms the left and right center of the housing 29 and a pair of side cases 42 that form the left and right ends. The center case 41 is formed to have the same width as the platform 13 of the weighing unit 4 and is placed on the platform 13. Each side case 42 has a joining wall 43 that extends downward along the outer surface of the platform 13 and is joined to the outer surface, and a side wall 44 that forms the left or right surface of the housing 29. The side walls 44 face each other laterally, with the heating coil 24 and inverter board 25 between them. A first upper support piece 45 that protrudes outward and supports the top frame 32 from below, and a second upper support piece 46 that protrudes inward and supports the support flange 35 from below, are formed at the upper end of each of the side walls 44.

[0025] Of the two temperature sensors 27 and 28 that make up the heating unit 3, the first temperature sensor 27 is a thermistor that is in close contact with the center of the underside of the top panel 33 of the top plate 2 and detects the temperature, and is supported by a sensor bracket 49 that stands upright from the upper surface of the partition wall 26 toward the center hole of the heating coil 24. The second temperature sensor 28 is a radiation thermometer that detects the temperature of infrared rays radiated from the top panel 33 and is disposed in a reclining position on the underside of the partition wall 26. A triangular prism 50 with a 45-degree reflective surface is disposed in front of the second temperature sensor 28, and a detection hole 51 is opened in the center of the partition wall 26 that faces the reflective surface of the prism 50 and the center hole of the heating coil 24. In other words, infrared rays emitted downward from the center of the underside of the top plate 33 pass through the central hole of the heating coil 24 and the detection hole 51 to reach the prism 50, where they are reflected horizontally by its reflective surface toward the second temperature sensor 28, and their temperature is detected by the second temperature sensor 28.

[0026] As shown in FIG. 4 , an air intake port 54 is provided on the front surface of the housing 29 of the heating unit 3, and an exhaust port 55 is provided on the rear surface of the housing 29. A cooling mechanism 56 for cooling the heating unit 3 is disposed on the inner surface of the front wall 16 of the casing 1. The cooling mechanism 56 includes a supply duct 57 extending vertically along the inner surface of the front wall 16 and an axial-flow cooling fan 58 housed inside the supply duct 57. When the cooling fan 58 is driven, an upward airflow is formed in the supply duct 57. An intake port 59 for taking in outside air is formed at the lower end of the supply duct 57, and an outlet port 60 for blowing out air is formed at the upper end of the supply duct 57. The outlet port 60 opens rearward and faces closely to the air intake port 54 of the heating unit 3 (facing it via a gap).

[0027] The air blown out from the air outlet 60 toward the air intake port 54 is divided into two parts, one above the other below the partition wall 26, and flows from the front (air intake port 54) to the rear (air exhaust port 55) within the housing 29. The air flowing above the partition wall 26 cools the heating coil 24 and the top plate 33, and the air flowing below the partition wall 26 cools the inverter board 25. To ensure this division of air, the front end of the partition wall 26 extends to the air intake port 54, and an air guide piece 61 is provided that continues from the front end of the partition wall 26 and extends to the air outlet 60. The air guide piece 61 is inclined downward and forward toward the air outlet 60, and its tip extends slightly into the supply duct 57 (however, it does not touch the wall surface of the supply duct 57).

[0028] 3, the heating coil 24 is placed on the upper surface of the partition wall 26 via a plurality of spacers 64 arranged at equal intervals around the periphery, and the partition wall 26 is supported by a lower support piece 65 integrally provided on the inner surface of the housing 29. In other words, the heating coil 24 is indirectly supported by the housing 29 via the spacers 64 and the partition wall 26. The partition wall 26 is integrally provided with a pair of left and right air passage walls 66 that define an air passage through which the heating coil 24 passes, and a hook piece 67 supported by the lower support piece 65 of the housing 29 protrudes from the outer surface of each air passage wall 66. The lower support piece 65 is provided contiguous with the tip of the second upper support piece 46 described above.

[0029] The inverter board 25 is supported on the bottom surface of the housing 29 and specifically comprises a rectangular board main body 70 that is slightly smaller than the bottom surface of the center case 41, and a heat sink 71 for heat dissipation that is erected on the right half of the board main body 70. The heat sink 71 is surrounded from above and to the left and right by air collection ducts 72 that open at the front and rear ends. As shown in FIG. 4, a pair of end portions 73 of the heating coil 24 are electrically connected to the board main body 70. Each end portion 73 extends downward toward the inverter board 25 through a through-hole provided in the partition wall 26 and, like the main body of the heating coil 24, is made of thick, rigid Litz wire.

[0030] As described above, the cooker according to this embodiment includes the top plate 2 on which the object to be heated is placed, the heating unit 3 that supports the top plate 2 from below and heats the object to be heated, and the weighing unit 4 that supports the heating unit 3 from below and measures the weight of the object to be heated. In other words, the weighing unit 4 is subjected to the load of the heating unit 3 and the load of the top plate 2 including the object to be heated, and the top plate 2 and the heating unit 3 are configured to move up and down together in accordance with the weight of the object to be heated on the top plate 2.

[0031] In addition, in this embodiment, the heating unit 3 is configured to include a heating coil 24 that generates an induction magnetic field above the top plate 2, an inverter board 25 that supplies a high-frequency current to the heating coil 24, and a housing 29 that houses and supports the heating coil 24 and the inverter board 25. When the heating coil 24 and the inverter board 25 are integrated into the heating unit 3 in this manner, the two 24 and 25 do not displace relative to each other, and therefore the end portion 73 of the heating coil 24, which is made of a thick Litz wire, i.e., the connection portion with the inverter board 25, does not interfere with the up and down movement of the heating unit 3 including the heating coil 24. In other words, according to this embodiment, the influence of the connection portion between the heating coil 24 and the inverter board 25 can be eliminated, and the weight of the object to be heated placed on the top plate 2 can be measured more accurately.

[0032] Since the control unit 5 is located below the weighing unit 4, a sufficient vertical distance can be secured between the heating unit 3 and the control unit 5, allowing the two units 3 and 5 to be loosely connected by a relatively long cable 6. This reduces the effect on the measured value of the weighing unit 4 of fluctuations in the tension of the cable 6 caused by the heating unit 3 moving up and down, thereby enabling more accurate measurement of the weight of the object to be heated.

[0033] The weighing unit 4 is supported from below by a base member 8 that houses the control unit 5, so that the weighing unit 4 is prevented from being placed directly on the control unit 5, and therefore the weight of the weighing unit 4 is prevented from being applied to the control unit 5.

[0034] Partition wall 26 is provided to separate heating coil 24 and inverter board 25 from each other above and below, so that room-temperature air that has not been heated by heat exchange is supplied to each of heating coil 24 and inverter board 25, allowing both heating coil 24 and inverter board 25 to be air-cooled accurately. Furthermore, lower support piece 65 that supports partition wall 26 and upper support pieces 45 and 46 that support top plate 2 are provided at the top of housing 29, and both partition wall 26 and top plate 2 are supported by housing 29, so that heating coil 24 on partition wall 26 can be easily and accurately positioned in the vertical direction relative to top plate 2. Accurate positioning of heating coil 24 relative to top plate 2 optimizes the distance from heating coil 24 to the object to be heated on top plate 2, allowing the object to be stably heated. [Explanation of symbols]

[0035] 2 top plate 3 Heating Unit 4 Weighing Unit 5. Control Unit 6 Cables 8 Base material 24 heating coil 25 Inverter board 26 Bulkhead 29 Case 45·46 Upper support piece 64 spacer 65 Lower support piece

Claims

1. a top plate (2) on which an object to be heated is placed; a heating unit (3) that supports the top plate (2) from below and heats the object to be heated; a weighing unit (4) that supports the heating unit (3) from below and measures the weight of the object to be heated; It is equipped with An electromagnetic induction heating cooker characterized in that the heating unit (3) comprises a heating coil (24) that generates an induction magnetic field above the top plate (2), an inverter board (25) that supplies high-frequency current to the heating coil (24), and a housing (29) that houses and supports the heating coil (24) and the inverter board (25).

2. The heating unit (3) includes a control unit (5) connected to the heating unit (3) by a cable (6), 2. The electromagnetic induction cooking appliance according to claim 1, wherein the control unit (5) is disposed below the measuring unit (4).

3. 3. The electromagnetic induction cooking appliance according to claim 2, further comprising a base member (8) that supports the measuring unit (4) from below and houses the control unit (5).

4. The heating unit (3) includes a partition wall (26) that separates the heating coil (24) and the inverter board (25) from each other above and below. The heating coil (24) is supported on the upper surface of the partition wall (26) via a spacer (64), An electromagnetic induction heating cooker as described in any one of claims 1 to 3, wherein a lower support piece (65) supporting the partition wall (26) and upper support pieces (45, 46) supporting the top plate (2) are provided at the upper part of the housing (29).

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