JP2009252632A - Heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating cooker capable of improving heating efficiency and reducing influence of thermal expansion of a heating element. <P>SOLUTION: A plurality of winding sections 46 are arranged on an insulating base plate 41 so as to radially extend from its central section of the insulating base plate, a space between winding sections 46, 46 adjoined in the peripheral direction is set up to be within a designated angle, and a ribbon heater 42 is wound so as to be built between the winding sections 46, 46. Thus, the ribbon heater can be wound between respective winding sections 46, 46 with comparatively short heater lengths. Consequently, absolute amounts of extensions of the ribbon heater 42 between respective winding sections 46, 46 become small and bending of the ribbon heater 42 is also restrained even though thermal expansion of the ribbon heater 42 is generated owing to current conduction, and reduction in heat transmission efficiency and disconnection of the ribbon heater 42 can be prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heating cooker that heats a cooking utensil placed on a top plate.

In the above-mentioned cooking device, there is a problem of how to heat a cooked utensil made of a material having a low dielectric constant and high electrical conductivity, such as an aluminum or copper pan. As a conventional technique for solving this problem, an aluminum plate is inserted between the top plate (top plate) and the induction heating coil, and the pan is indirectly heated by induction heating the aluminum plate. An induction heating device has been proposed (see, for example, Patent Document 1).
However, the induction heating device of Patent Document 1 is configured to indirectly heat the pan through the aluminum plate (that is, the aluminum plate is induction-heated in the same manner as the pan). Since the loss in the induction heating coil increases, there is a problem that the heating efficiency is low.

Thus, a cooking device has been proposed in which a heating element is provided between the top plate and the induction heating coil, and the heating element generates heat when energized to heat the pan (see, for example, Patent Document 2). . The heating element is formed in a hollow ring shape from a strip-shaped stainless steel conductor, and is supported from the lower surface side of the heating element so as to be in close contact with the lower surface of the top plate. In this case, a reinforcing plate as a support member for the heating element and a heat insulating member are disposed on the lower surface side of the heating element.
Japanese Patent No. 3465712 JP 2007-123159 A

  However, the heating element of Patent Document 2 is deformed so that it swells up and down due to thermal expansion of the heating element itself by energization, so that a part of the heating element is separated from the top plate and the reinforcing plate, and there is a gap around the heating element. Can occur. Therefore, in this type of heating element, heat transfer efficiency is lowered in the gap portion, and an abnormal temperature rise is caused to cause red heat and become brittle, and there is a risk of disconnection.

  This invention is made | formed in view of said subject, The objective is to provide the heating cooker which can reduce the influence by the thermal expansion of a heating body while being able to improve heating efficiency. is there.

  In order to achieve the above object, a heating cooker according to the present invention includes a top plate on which a cooked utensil is placed, and a cooked dish that is provided below the top plate and placed on the top plate. An induction heating coil for induction-heating the appliance, and a plate-like heating body that is disposed between the top plate and the induction heating coil and that heats the cooked appliance placed on the top plate. In the heating cooker, the plate-like heating body includes a belt-like heater that generates heat when energized, and a plate-like insulating substrate having a winding portion for winding the heater, and the winding portion is The insulating substrate is provided with a plurality so as to extend radially from the central portion thereof, and the interval between the winding portions adjacent in the circumferential direction is set within a predetermined angle, and the heater is adjacent in the circumferential direction. Fit Characterized in that it is wound as stretched between Kimaki times section.

According to the said structure, the to-be-heated cooking utensil can be directly heated with the heater of a plate-shaped heating body regardless of the material, and heating efficiency can be improved.
Moreover, the length (line length) between the winding parts in the said heater has the relationship which becomes long when the angle between the winding parts adjacent to the circumferential direction is large, and becomes short when it is small. Therefore, according to the above configuration, the heater can be wound with a relatively short line length between the winding portions by setting the interval between the winding portions adjacent in the circumferential direction within a predetermined angle. it can. Therefore, even if thermal expansion occurs in the heater due to energization, the absolute amount of elongation of the heater between the winding portions is reduced and the bending thereof is suppressed, so that the contact state of the heater with the top plate can be maintained well. It is possible to prevent a decrease in heat transfer efficiency and disconnection of the heater.

<First embodiment>
The induction heating cooker according to the first embodiment of the present invention is shown in FIG. The induction heating cooker 10 includes a main body case 12 and a top plate 13 that constitute a cooker main body 11.
The induction heating cooker 10 is provided so that the top plate 13 is on the upper side in the direction of gravity. In FIG. 2, the left side is the front side of the induction heating cooker 10, and the right side is the rear side of the induction heating cooker 10. The induction heating cooker 10 includes a heating unit 14 and a cooling fan unit 15 in a cooking appliance body 11.

  The main body case 12 forms a main outline of the induction heating cooker 10, and the upper portion of the main body case 12 is covered with a top plate 13. The cooker main body 11 is incorporated in a countertop 16 of a system kitchen, for example (so-called built-in type), so that the top plate 13 is exposed to the countertop 16. On the top surface of the top plate 13, a pan 17 indicated by a two-dot chain line is placed as a cooking utensil to be heated. The pan 17 placed on the top plate 13 is heated by heating means accommodated in the main body case 12. The top plate 13 is formed in a rectangular flat plate shape using, for example, tempered heat resistant glass. The top plate 13 has openings 18 for intake and exhaust at the rear. In the case of the present embodiment, the opening 18 is provided for exhaust on the left side behind the top plate 13 and for intake on the right side. A heating control unit 19 is accommodated in the main body case 12 of the cooker main body 11.

  As shown in FIG. 3, the induction heating cooker 10 includes an induction heating coil 21 and a plate-like heating body 22 as a heating unit 14 that constitutes a heating unit. The induction heating cooker 10 includes a plurality of heating means such as a plurality of induction heating coils 21 and a roaster function including a sheathed heater as another heating means. Moreover, the induction heating cooking appliance 10 may be equipped with the heating means other than the above illustrated. Illustration and description of these other heating means are omitted.

  In the case of the present embodiment, the induction heating coil 21 and the plate-like heating body 22 constitute the heating unit 14 and are provided at the same position in the plan view of the induction heating cooker 10. That is, the induction heating coil 21 and the plate-like heating body 22 constituting the heating unit 14 are integrally supported at a predetermined position of the main body case 12. The heating unit 14 is pressed against the lower surface of the top plate 13 by an elastic body 23 having, for example, a compression coil spring. Thereby, the heating unit 14 is in close contact with the lower surface of the top plate 13.

  The heating unit 14 will be described with reference to FIGS. Here, FIG. 4 is an exploded perspective view of the heating unit 14, and FIG. 7 is a cross-sectional view schematically showing a part of the heating unit 14. As shown in FIGS. 3 and 4, the heating unit 14 includes a support member 24 and a heat insulating material 25 in addition to the induction heating coil 21 and the plate-like heating body 22. The support member 24 supports the plate-like heating body 22 on the top plate 13 side of the induction heating coil 21. The support member 24 is provided so as to form a predetermined gap with the induction heating coil 21. Thereby, the channel | path 26 through which air flows is formed between the plate-shaped heating body 22 and the induction heating coil 21 of the heating unit 14 (refer FIG. 3, FIG. 7).

  A central hole 24a is formed at the center of the support member 24, and fan-shaped notches 24b as shown in FIG. 4 are formed around the central hole 24a at intervals of 90 degrees, for example. The heat insulating material 25 is provided between the plate heater 22 and the induction heating coil 21. The heat insulating material 25 blocks heat generated from the plate-like heating body 22 from being transmitted from the plate-like heating body 22 to the induction heating coil 21 side. The heat insulating material 25 is formed with a central hole 25 a and a notch 25 b similar to the support member 24. The central hole 25a and the notch 25b of the heat insulating material 25 and the center hole 24a and the notch 24b of the support member 24 are connected so as to be connected to each other.

  The cooling fan unit 15 is provided inside the main body case 12 as shown in FIG. The cooling fan unit 15 includes a fan 27 and a fan motor 28. As the fan 27 rotates, the air sucked from the intake opening 18 is discharged from the exhaust opening 18 via the heating unit 14 and the heating control unit 19. Thereby, the cooling fan unit 15 forms a flow of cooling air and cools the heating unit 14 and the heating control unit 19.

  The heating control unit 19 is connected to an inverter 29 that constitutes a high-frequency current supply unit as shown in FIG. That is, the heating control unit 19 has a circuit board on which a heat-generating switching element such as an IGBT that constitutes the main circuit of the inverter 29 is mounted. The exothermic element of the heating control unit 19 is cooled by the wind generated by the cooling fan unit 15.

Next, the heating unit 14 will be described in detail.
The induction heating coil 21 constituting the heating unit 14 is formed in a hollow disk shape as shown in FIG. The induction heating coil 21 is supported at a position away from the top plate 13 by a predetermined distance. The induction heating coil 21 is supported by a base plate 31 made of heat resistant resin as shown in FIG. The base plate 31 has cylindrical leg portions 32 that protrude downward at a plurality of positions on the outer peripheral portion. As shown in FIG. 2, an elastic body 23 is attached between the leg portion 32 and the inner frame member 33 of the main body case 12. Thereby, the induction heating coil 21 supported by the base plate 31 is pressed against the top plate 13 side. By supplying a high frequency current to the induction heating coil 21, an eddy current is generated in the pan 17 placed on the top plate 13. Due to this eddy current, Joule heat is generated in the pan 17 and the pan 17 is heated.

  On the other hand, the plate-like heating body 22 constituting the heating unit 14 includes an insulating substrate 41 and a ribbon heater 42 as shown in FIG. In this embodiment, the insulating substrate 41 is made of ceramics as an insulator. The insulating substrate 41 is preferably formed from ceramics having high thermal conductivity. The ribbon heater 42 is formed in a belt shape and constitutes a heater in the claims. As the ceramic forming the insulating substrate 41, for example, aluminum nitride, silicon nitride, or alumina can be applied. Aluminum nitride has a high thermal conductivity, and uniformly transfers the heat of the ribbon heater 42 to the top plate 13 side. On the other hand, aluminum nitride has a weak point that it is vulnerable to impact. Therefore, by forming the insulating substrate 41 with silicon nitride, the strength against impact can be improved as compared with aluminum nitride. Moreover, the insulating substrate 41 can be formed at low cost by forming the insulating substrate 41 from alumina. The material of these ceramics is not limited to the above example, but can be arbitrarily changed according to the requirements according to the specifications of the induction heating cooker 10 to which the insulating substrate 41 is applied.

  The insulating substrate 41 is formed in a substantially disc shape as a whole, and alternately has holes 43 and slits 44 at substantially equal intervals in the circumferential direction. In this case, as will be described in detail later, the holes 43 and the slits 44 extend radially, and the distance between them is set to 45 degrees, for example. The hole 43 and the slit 44 are formed so as to penetrate the insulating substrate 41 in the plate thickness direction, and both ends of the hole 43 are closed by the insulating substrate 41 in the radial direction of the insulating substrate 41. On the other hand, the slit 44 is open at the outer peripheral end in the radial direction of the insulating substrate 41. A sensor hole 45 penetrating the insulating substrate 41 in the thickness direction is provided at the center of the insulating substrate 41.

  As shown in FIGS. 1 and 8, the insulating substrate 41 is provided with a plurality of winding portions 46 extending radially from the central portion thereof. Specifically, in the insulating substrate 41, a plurality of protrusions 48 projecting in the circumferential direction of the insulating substrate 41 are integrated with the side wall 41 a (see FIG. 6) facing the hole 43 and the slit 44 and facing in the circumferential direction. Provided. These protrusions 48 are arranged so as to be continuous in the radial direction along the holes 43 and the slits 44, and constitute the winding portions 46 in the respective side wall portions 41a. Therefore, the insulating substrate 41 is provided with a plurality of winding portions 46 in the circumferential direction. And the space | interval between the winding parts 46 and 46 adjacent to the circumferential direction is set so that it may become in a predetermined angle, and is set to 45 degrees same as the space | interval of the hole 43 and the slit 44 in a present Example, for example. Has been. Here, the winding parts 46 and 46 adjacent to each other in the circumferential direction refer to a pair of winding parts 46 and 46 having a relationship that can be considered as a pair of radii in a sector shape.

The configuration near the protrusion 48 will be described in detail with reference to FIG. 6A is an enlarged view of a region surrounded by P1 in FIG. 1, and FIG. 6B is a longitudinal sectional view taken along line X1-X1 in FIG. 6A.
The protruding portion 48 forms a hole 43 and a slit 44 and protrudes from one of the opposing side wall portions 41a and 41a toward the other, and has end portions 48a and 48b at both ends in the radial direction of the insulating substrate 41, respectively. ing. That is, the protrusion 48 has an end 48 a on the outer peripheral side in the radial direction of the insulating substrate 41 and an end 48 b on the inner peripheral side. The protrusion 48 and the side wall 41a constitute a folded portion 47.

  The ribbon heater 42 is wound around the top plate 13 side (surface side) of the insulating substrate 41 so as to be spanned between the winding portions 46 and 46 adjacent in the circumferential direction. The ribbon heater 42 is folded while being hooked by the folding portion 47 at the winding portion 46. In this case, a part of the ribbon heater 42 passes through the induction heating coil 21 side (rear surface side) of the projection 48 between the end 48 a and the end 48 b of the projection 48, and is folded back by the folding portion 47. Only the exposed part is exposed to the induction heating coil 21 side.

  In the present embodiment, as described above, a plurality of projections 48 are provided in the radial direction along the holes 43 and the slits 44, and a row of the projections 48 is provided on each side wall 41 a of the insulating substrate 41. Thus, the plate-like heating body 22 (insulating substrate 41) has a plurality of folded portions 47 in the radial direction and a plurality of rows of the folded portions 47 in the circumferential direction. The number and interval of the holes 43 and the slits 44 provided in the insulating substrate 41, the shape of the projections 48, and the like can be arbitrarily changed.

  The distance from the side wall 41a of the insulating substrate 41, which is the bottom of the protrusion 48, to the tip of the protrusion 48, that is, the protrusion amount of the protrusion 48 is set for the following reason. The ribbon heater 42 expands due to heat generation when energized, and the total length increases. At this time, if the expansion amount of the ribbon heater 42 becomes excessive, the ribbon heater 42 that is hooked on the protrusion 48 may be detached from the protrusion 48. If the ribbon heater 42 is disengaged from the protrusion 48, the ribbon heater 42 may come into contact with the adjacent ribbon heater 42, causing a short circuit between the ribbon heaters 42. Therefore, in the present embodiment, the distance from the bottom to the tip of the protrusion 48 is set to be larger than the extension amount of the ribbon heater 42 between the winding portions 46 and 46 when energized.

  In this embodiment, two ribbon heaters 42 are disposed on the insulating substrate 41. The ribbon heater 42 is made of a resistance heating material as a heater wire (generates Joule heat when energized), and each end portion is taken out as a terminal 49 from the terminal hole 50 of the insulating substrate 41 to the outside. The pair of ribbon heaters 42 are wound so as to be vertically symmetrical in the upper half and the lower half of the insulating substrate 41 in FIG. In this case, the ribbon heater 42 is folded while being hooked on the folding portion 47 as described above, so that most of the ribbon heater 42 is located on the front surface side and is wound around the winding portions 46 and 46 in the circumferential direction. Turned. Thus, the ribbon heater 42 is sequentially wound from the outer peripheral side of the insulating substrate 41 to the inner peripheral side (or from the inner peripheral side to the outer peripheral side) between the winding portions 46 and 46.

  Here, the winding length of the ribbon heater 42 between the winding portions 46 and 46 (hereinafter referred to as the line length a of the ribbon heater 42) will be described with reference to the schematic diagram of FIG. FIG. 8A is a schematic plan view showing an enlarged main part of the plate-like heating body 22, and as shown in FIGS. 8B and 8C, the line length a of the ribbon heater 42 is expressed by a trigonometric function. Can be deducted from.

That is, the ribbon heater 42, when substantially wound spanned perpendicularly to the winding portion 46 along the hole 43 (in FIG. 8 (a), the reference dashed a _1), insulating the take-up portion 46 substrate 41 Ribbon, where b _{1 is} the distance (the length of line segment A, B ₁ ) from the center A of the wire to the winding position (folding position) B ₁ and the central angle between the windings 46, 46 is θ line length _{a 1} of the heater 42 is calculated, for example, the following equation (1) (see Figure 8 (b)).

a ₁ = b ₁ tan θ (1)
Further, when winding the ribbon heater 42 in the circumferential direction, in other words, the distances b ₂ and c ₂ from the central portion A to the winding positions (B ₂ and C ₂ ) in the respective winding portions 46 are determined. When winding to be equal (b ₂ = c ₂ , see the broken line a ₂ in FIG. 8A), the wire length a ₂ of the ribbon heater 42 is calculated by the following equation (2), for example (FIG. 8). (See (c)).

a ₂ = 2b ₂ sin (θ / 2) (2)
From equations (1) and (2), by setting the central angle θ within a predetermined angle, each line length a (a ₁ , a ₂ ) of the ribbon heater 42 is a predetermined length ( Details will be described in the second embodiment). Therefore, the ribbon heater 42 is wound so that the wire length a is relatively short between the winding portions 46 and 46. In this embodiment, as shown in FIG. 1, in the radial direction of the insulating substrate 41, the ribbon heater 42 has the shortest heater portion 42a having the shortest line length a on the inner circumference (center) side of the insulating substrate 41. The longest heater portion 42b having the longest line length a is provided on the outer peripheral side of the insulating substrate 41. Since the ribbon heater 42 is wound substantially perpendicularly to the winding portion 46 along the hole 43, the length dimension of the shortest heater portion 42a and the longest heater portion 42b can be calculated by the equation (1). it can.

  Next, the electrical configuration of the induction heating cooker 10 will be described with reference to FIG. The heating control unit 19 is provided inside the cooker body 11 and is configured by a microcomputer (not shown).

  An operation unit 51 and a temperature sensor 52 are connected to the heating control unit 19. The operation unit 51 is disposed in front of the top plate 13 on the outside of the cooker main body 11 and outputs the input information to the heating control unit 19 as an operation signal. The temperature sensor 52 detects the temperature of the top plate 13. The temperature sensor 52 outputs the detected temperature of the top plate 13 to the heating control unit 19 as an electric signal. The heating control unit 19 also functions as a material determination unit that determines the material of the cooked utensil such as the pan 17 placed on the top plate 13. The heating control unit 19 controls the inverter 29 based on a control signal input from the operation unit 51 and the temperature sensor 52 and a control program stored in advance. Thereby, the heating control unit 19 supplies the high-frequency current to the induction heating coil 21 via the inverter 29 and controls the induction heating coil 21. A resonance capacitor 53 is connected to the induction heating coil 21 in series. The induction heating coil 21 and the resonant capacitor 53 are preferably configured such that the number of turns of the coil and the capacity of the capacitor are variable in order to adjust the output according to the material of the pan 17.

  The inverter 29 is supplied with driving power converted into direct current by the rectifier circuit 55 from the commercial AC power supply 54. Similarly, the energization control unit 56 controls the power supplied from the commercial AC power supply 54 to the plate heater 22. The energization control unit 56 supplies AC power to the plate heater 22. The electric power supplied from the energization control unit 56 to the plate-like heating body 22 is comprehensively controlled by the heating control unit 19. Current transformers 57 and 58 are disposed on the input side of the rectifier circuit 55 and the output side of the inverter 29, respectively. The current values detected by the current transformers 57 and 58 are both input to the heating control unit 19. Thereby, the heating control unit 19 detects the input current value input from the commercial AC power supply 54 and the output current value of the inverter 29.

  The heating control part 19 determines the material of this pan 17 by determining whether the pan 17 which is a to-be-heated cooking appliance is a metal material with big resistance. For example, the heating control unit 19 supplies a constant high-frequency current to the induction heating coil 21, and determines the material of the pan 17 based on the relationship between the input current and the coil current that is the output current of the inverter 29. For example, when the pan 17 is formed of a ferromagnetic material such as iron, the magnetic flux generated by the induction heating coil 21 easily flows through the pan 17. And the skin effect which an eddy current concentrates on the induction heating coil 21 side in the bottom part of the pan 17 also becomes high. Therefore, the equivalent resistance of the induction heating coil 21 increases. On the other hand, when the material of the pan 17 is nonmagnetic or weakly magnetic such as aluminum or copper and the specific resistance is small, the magnetic flux generated by the induction heating coil 21 is difficult to reach the pan 17 and the leakage magnetic flux increases. . Since the specific resistance is small and the skin effect is difficult to obtain, the equivalent resistance decreases. As a result, the heating control unit 19 can determine the material of the pan 17 based on the magnitude change between the input current and the output current. Accordingly, the heating control unit 19 determines the material of the pan 17 and selects heating by the induction heating coil 21 of the pan 17 or heater heating by the plate heater 22 based on the preset input power setting value. Can be executed.

Next, the operation of the induction heating cooker 10 having the above configuration will be described.
When the pan 17 containing the object to be cooked is placed at a predetermined position on the top plate 13 and a necessary input operation is performed by the operation unit 51, the heating control unit 19 starts heating the pan 17. If the heating control part 19 determines with the material determination process that the material of the pan 17 is a high resistance metal, the heating control part 19 will perform the induction heating cooking by the induction heating coil 21 based on normal input electric power. On the other hand, when it is determined that the material of the pot 17 is not a high resistance metal, the heating control unit 19 determines whether the material of the pot 17 is a low resistance nonmagnetic metal such as aluminum, copper or nonmagnetic stainless steel, Determine whether it is non-metallic or unloaded. And if it determines with the pan 17 being a low resistance metal, the heating control part 19 will preset the heat-power adjustment so that the bottom of the pan 17 may repel and move by the top plate 13 may not be produced. Based on the above, induction heating cooking is executed.

  Here, when the heating power becomes smaller than the normal input power set value due to the thermal power adjustment, the heating control unit 19 supplies the difference power to the plate-like heating body 22 via the energization control unit 56. Thereby, the heating control unit 19 heats the pan 17 placed on the top plate 13 with the plate-like heating body 22. Further, when the pan 17 is made of a low-resistance nonmagnetic metal, the equivalent resistance of the induction heating coil 21 is reduced. Therefore, the heating control unit 19 lowers the voltage output to the induction heating coil 21 via the inverter 29 as compared with the case of a high-resistance magnetic metal or increases the frequency of the voltage. Thereby, the heating control part 19 aims at the improvement of heating efficiency.

  In addition, when the pan 17 is formed of a non-metal or when there is no load, the heating control unit 19 does not perform induction heating by the induction heating coil 21. Therefore, the heating control unit 19 supplies power equal to the normal input power set value from the energization control unit 56 to the plate-like heating body 22 and performs heating only by the plate-like heating body 22. In this case, the heating control unit 19 needs to determine whether the pan 17 is non-metallic or unloaded. Therefore, the heating control unit 19 detects a temperature change of the top plate 13 after the temperature sensor 52 starts energizing the plate-like heating body 22. At this time, the heating control unit 19 determines that a clay pot or the like is placed if the change in the temperature of the top plate 13 is gentle, and determines that there is no load if the change in temperature is rapid.

  When it determines with the to-be-heated cooking utensils, such as the pan 17, being a nonmetallic material, the heating control part 19 performs the heating of the pan 17 with the plate-shaped heating body 22. FIG. At this time, since most of the ribbon heater 42 is provided on the upper surface side except the portion passing through the back surface side in the folded portion 47, most of the heat generated from the ribbon heater 42 passes through the top plate 13. It is transmitted to the pan 17. Further, since the ribbon heater 42 is wound with a relatively short wire length a, even if thermal expansion occurs in the ribbon heater 42 due to energization, the amount of expansion of the ribbon heater 42 between the winding portions 46 and 46 is different. Small deflection is also suppressed. Therefore, the pan 17 is efficiently heated by the plate-like heating body 22.

  After this heating is completed, heat remains in the top plate 13 and the plate-like heating body 22, so the heating control unit 19 rotationally drives the fan 27 of the cooling fan unit 15. At this time, the air flowing between the induction heating coil 21 and the support member 24 is partly heated via the notch 25b of the heat insulating material 25 and the notch 24b of the support member 24 as shown in FIG. It flows to the back side of the body 22. The air flow is in contact with the ribbon heater 42 located on the back side of the plate heater 22. Thereby, the ribbon heater 42 dissipates heat at the portion located on the back side of the plate-like heating body 22 and the portion located on the front side is also cooled. As a result, the top plate 13 whose temperature has been increased by the heating of the pan 17 is rapidly cooled by the air flow by the cooling fan unit 15.

  As described above, the heating control unit 19 performs heating cooking by the induction heating coil 21, heating cooking by the plate-like heating body 22, or heating cooking by a combination thereof according to the material of the cooking utensil such as the pan 17. To do. And the heating control part 19 promotes cooling of the top plate 13 and the plate-shaped heating body 22 by driving the cooling fan part 15 after cooking is completed.

  As described above, the ribbon heater 42 of the plate heater 22 generates heat when energized. The cooked utensils such as the pan 17 placed on the top plate 13 are directly heated by the plate-like heating body 22 that generates heat. Therefore, the cooked utensils such as the pan 17 can be heated regardless of the material, and the heating efficiency can be increased.

  A plurality of winding portions 46 are provided on the insulating substrate 41 so as to extend radially from the central portion A, and the interval between the winding portions 46 and 46 adjacent to each other in the circumferential direction is set within a predetermined angle. The ribbon heater 42 was wound around the winding portions 46 and 46. According to this, the line length a between the winding parts 46 and 46 in the ribbon heater 42 can be deduced by the above formulas (1) and (2). The ribbon heater 42 can be wound with a relatively short line length a between the winding portions 46 and 46 by setting the central angle θ within a predetermined angle. Accordingly, even if thermal expansion occurs in the ribbon heater 42 due to energization, the absolute amount of elongation of the ribbon heater 42 between the winding portions 46 and 46 is reduced, and the bending thereof is also suppressed. Therefore, the top plate 13 of the ribbon heater 42 is suppressed. The contact state with respect to can be maintained well.

  That is, unlike the present embodiment, when the ribbon heater wire length is not regulated (in the case of a long wire length), for example, the ribbon heater is deformed so that it swells up and down due to thermal expansion. Not only does the stress act, but a gap may be formed between the ribbon heater and the top plate. In this case, since the heat transfer efficiency is reduced in the gap portion and the abnormal temperature rise of the ribbon heater is caused, the ribbon heater becomes red hot and becomes brittle and may be broken. On the other hand, in the present embodiment, by suppressing the bending of the ribbon heater 42, it is possible to extend the life by solving the problems of the decrease in heat transfer efficiency and the disconnection of the ribbon heater 42. Further, since the stress acting on the insulating substrate 41 is reduced, the thickness of the insulating substrate 41 can be set to be thin, and the elongation of the ribbon heater 42 is also suppressed. The disconnection can be prevented, and a short circuit between adjacent ribbon heaters 42 can be eliminated.

  The ribbon heater 42 wound as described above has the maximum expansion amount when energized in the longest heater portion 42b. In this respect, since the ribbon heater 42 is wound within a predetermined length range between the winding portions 46, 46, the expansion and deflection including the longest heater portion 42b can be reduced as much as possible. The influence due to expansion can be reliably reduced.

The ribbon heater 42 is provided mostly on the top plate 13 side of the insulating substrate 41 by providing the winding portion 46 with the folded portion 47 where the ribbon heater 42 is folded. Therefore, most of the heat generated from the ribbon heater 42 is used for heating the pan 17 on the top plate 13 side, so that the heating efficiency by the ribbon heater 42 can be further increased.
The ribbon heater 42 is hooked on the protrusion 48 and is folded back to one side (the top plate 13 side). Therefore, the winding operation of the ribbon heater 42 is performed by repeatedly passing the ribbon heater 42 in the circumferential direction on one side of the insulating substrate 41 and hooking the ribbon heater 42 on the protrusion 48 at the winding portion 46. Therefore, the ribbon heater 42 can be wound around the insulating substrate 41 relatively easily, and the number of assembling steps of the plate heater 22 can be reduced.

The protrusion amount of the protrusion 48, that is, the distance from the bottom to the tip of the protrusion 48, is set to be larger than the expansion amount of the ribbon heater 42 that expands when heat is generated. Therefore, dropping of the ribbon heater 42 from the protrusion 48 is reduced during heat generation. Accordingly, it is possible to prevent contact between the ribbon heaters 42 that are separated from the protrusion 48.
In the first embodiment, the ribbon heater 42 is exposed to the induction heating coil 21 side only at the portion of the folded portion 47 that is folded back by the protrusion 48. Thereby, the plate-shaped heating body 22 has a small amount of heat generation to the induction heating coil 21 side. For this reason, the induction heating coil 21 is reduced in thermal influence received from the plate-like heating body 22 when the plate-like heating body 22 generates heat. Therefore, the heat insulation between the plate-like heating body 22 and the induction heating coil 21 becomes easy, and the structure can be simplified.

<Second embodiment>
9 to 13 show a second embodiment of the present invention, and different points from the first embodiment will be described. 9 is a view corresponding to FIG. 1, FIGS. 10A and 10C are schematic views enlarging P2 and P3 portions in FIG. 9, and FIG. 10B is X2-X2 in FIG. 10A. The longitudinal cross-sectional view along a line is shown, and the same code | symbol is attached | subjected to the same part as 1st Example.

  The plate-like heating body 59 of the present embodiment is different from the plate-like heating body 22 of the first embodiment in the following points. That is, the insulating substrate 60 is composed of a plurality of, for example, twelve divided substrates 61 divided in the circumferential direction. As shown in FIG. 10B, the divided substrate 61 is a composite material in which a ceramic plate 62 made of the above ceramics and a mica plate 63 made of hard mica are vertically stacked, and the ceramic plate 62 is a divided substrate. The mica plate 63 is disposed so as to constitute the rear surface portion of the front surface portion 61.

  One of the adjacent divided substrates 61 corresponding to the divided surfaces 64 and 64 (see FIG. 13A) has an engaging convex portion 65 integrally formed on each of the inner peripheral portion and the outer peripheral portion. Is provided. Specifically, as shown in FIG. 10C, the engaging convex portion 65 is narrower than the diameter of the head portion 65a so as to connect the head portion 65a having a substantially circular shape and the head portion 65a and the dividing surface 64. A protruding base portion 65b is formed, and the head portion 65a and the protruding base portion 65b are integrated to form the engaging convex portion 65. The other divided substrate 61 is formed with a hole 66a slightly larger in diameter than the head 65a and an open portion 66b wider than the protruding base 65b in the vicinity of the divided surface 64 side of the hole 66a. The portion 66b constitutes an engaging recess 66.

  The adjacent divided substrates 61 and 61 are connected to each other by fitting (engaging) the adjacent engaging convex portions 65 and engaging concave portions 66 with each other. In the present embodiment, the insulating substrate 60 is configured by connecting the twelve divided substrates 61 in an annular shape, and the engaging convex portion 65 and the engaging concave portion 66 function as a coupling means. In addition, this coupling | bonding means should just connect or couple | bond the divided substrates 61 and 61, and is not limited to the said structure.

  A side wall portion (see FIG. 13A) that is recessed in the circumferential direction is formed on the divided surface 64 side of the divided substrate 61 so that a portion excluding the inner peripheral portion and the outer peripheral portion is narrowed. A plurality of protrusions 67 protruding in the circumferential direction of the insulating substrate 60 are integrally provided only on the side wall 63 a of the 63. These protrusions 67 constitute a winding part 68 by being arranged so as to be continuous along each side wall part 63a (see FIGS. 9 and 13A). The protruding amount of the protruding portion 67 is set to be larger than the extending amount of the ribbon heater 42 between the winding portions 68 and 68 when energized, like the protruding portion 48.

  The protrusion 67 corresponds to a folded portion, and the base end portion has a “C” shape in which the base end side is widened in a plan view, and an inclined portion (inclined by 45 degrees with respect to the protruding direction of the protrusion 67 ( (Tilt) 67a is formed. The ribbon heater 42 is wound on the surface side of the divided substrate 61 so as to be spanned between the winding portions 68 and 68, and is being hooked on the inclined portion 67 a of the protrusion 67 at the winding portion 68. Wrapped. By this inclined portion 67a, the ribbon heater 42 is folded back without waste so that no gap is generated in the winding portion 68, and is wound in a state where an appropriate tension is applied to each divided substrate 61. Further, a part of the ribbon heater 42 is exposed to the induction heating coil 21 side by passing through the back surface side of each protrusion 67 (between the inclined portions 67a and 67a). The portion is in contact with the ceramic plate 62.

  The winding portion 68 of the present embodiment extends substantially radially from the central portion of the insulating substrate 60 in a state where the divided substrates 61 are connected in a ring shape, and the interval between the winding portions 68 and 68 is the radial direction of the insulating substrate 60. It is provided so as to be constant from the middle. Here, the central angle θ between the winding portions 68 and 68 and the line length a of the ribbon heater 42 will be described with reference to the schematic diagram of FIG.

FIG. 13A is an enlarged plan view showing a part of the divided substrate 61. As shown in FIG. 13, the ribbon heater 42 has the longest heater portion 42b in the radial direction of the insulating substrate 60 (see FIG. 13). in 13 (a), see the broken line _{a 2),} it is wound for up heater unit 42b equivalent to the length in from the radially outer side of the insulating substrate 41 up to the heater unit 42b. In this case, the interval between the winding portions 68 and 68 is set so that the longest heater portion 42b is wound with a dimension of a predetermined length (for example, 25 mm) or less. The reason why the length of the longest heater portion 42b is set to 25 mm or less is as follows. That is, when heating is performed by the plate heater 59, the ribbon heater 42 may be bent due to thermal expansion and an abnormal temperature rise may occur depending on the line length a of the ribbon heater 42. Therefore, the inventor conducted an experiment and obtained the result that the abnormal temperature rise described above can be suppressed by setting the line length a of the ribbon heater 42 to 25 mm or less.

On the other hand, as shown in FIGS. 9 and 13B, when the ribbon heater 42 is wound around the circumferential direction, the wire length of the ribbon heater 42 is a ₂ , and the length of the longest heater portion 42 b from the center A is When the distance to the winding position (B ₂ and C ₂ ) is b ₂ (= c ₂ ), the central angle θ between the winding portions 68 and 68 is expressed by the following formula (2 ′) from the above formula (2). expressed.

θ = 2arcsin (a ₂ / 2b ₂ ) ( _{2 ′} )
From the equation (2 ′), the central angle θ for winding the ribbon heater 42 within a predetermined length can be calculated. Thus, for example, when the distance _{b 2} from the center portion A of the winding portion 68 of the longest heater portion 42b is 50 mm, the line length _{a 2} of the ribbon heater 42 is wound at 25mm or less, a central angle theta 30 degrees It can be said that it should be set within.

  Further, as shown in FIG. 9, the insulating substrate 60 (plate-like heating body 59) is provided with a conductor (hereinafter referred to as a conducting wire 69) for detecting intrusion of water or the like. The conducting wire 69 is hooked to the insulating substrate 60 by being inserted into a plurality of small holes 70 (a part of which is shown in FIG. 9) formed in the insulating substrate 60, and An annular detector 69a that is annularly arranged and an auxiliary detector 69b that protrudes from the annular detector 69a inward in the circumferential direction at equal intervals. The conducting wire 69 is close to the ribbon heater 42 but is separated from the ribbon heater 42 and is grounded via a current limiting resistor 71 shown in FIG. Moreover, the induction heating cooker 10 of the present embodiment includes a current transformer 72 that detects that a current has flowed through the lead wire 69 and a notification unit 73 as a notification unit. The detection signal of the current transformer 72 is given to the heating control unit 19, and the notification unit 73 is constituted by, for example, a buzzer built in the cooker body 11.

  If the top plate 13 is broken and water is applied to the ribbon heater 42, an electric current flows through the lead wire 69 through the water. Here, when the heating control unit 19 determines that a current is flowing through the conductive wire 69 based on the detection signal of the current transformer 72, the heating controller 19 cuts off the ribbon heater 42 and sounds the buzzer.

  By the way, in the present embodiment, most of the ribbon heater 42 is a so-called single-sided heater located on the surface side of the insulating substrate 60, and the ceramic plate 62 is the surface portion of the insulating substrate 60 and the mica plate 63 is the back surface portion. It is composed. This is due to the following reason.

  That is, FIG. 12 is a diagram showing the relationship between the input power [W] of the ribbon heater 42 and the temperature [° C.] of the ribbon heater 42 when boiling water by the plate heater 59. As shown in the figure, the temperature of the ribbon heater 42 increases in proportion to the input power of the ribbon heater 42. In particular, when the input power of the ribbon heater 42 exceeds 1200 W, the temperature exceeds 500 ° C., which is the upper limit temperature of use of hard mica. That is, when the material of the insulating substrate is composed only of mica, the mica is inferior in heat resistance, so that there is a problem that it cannot be used with input power exceeding 1200 W. Therefore, in this embodiment, the heat resistance of the insulating substrate 60 is improved by disposing the ribbon heater 42 so that most of the ribbon heater 42 is in contact with the ceramic plate 62 having excellent heat resistance. Further, the ribbon heater 42 is hooked (turned back) at the projection 67 of the mica plate 63 so as to resist stress caused by thermal expansion of the ribbon heater 42 or the like.

With the above configuration, the following effects are obtained in the second embodiment.
The interval between the winding parts 68 and 68 adjacent to each other in the circumferential direction is set within a predetermined angle (for example, 30 degrees), and the ribbon heater 42 is set to a predetermined length (for example, 25 mm) between the winding parts 68 and 68. ). In this way, by winding the ribbon heater 42 with a wire length a of 25 mm or less, an abnormal temperature rise due to the thermal expansion of the ribbon heater 42 can be reliably suppressed, and the influence of the thermal expansion of the ribbon heater 42 can be prevented. It can be reduced as much as possible.

  In addition, since the longest heater portion 42b is at least in the radial direction of the insulating substrate 60, in the configuration in which the winding portions 68 are radially arranged on the insulating substrate 60, the line length a on the outer peripheral side of the ribbon heater 42 is long. It can be suppressed. That is, since the length of the ribbon heater 42 between the winding portions 68 and 68 is suppressed regardless of the diameter size of the insulating substrate 60, the influence of thermal expansion of the ribbon heater 42 can be reduced, and the design can be reduced. The degree of freedom can also be increased.

The ribbon heater 42 is wound with a length equivalent to that of the longest heater portion 42b on the outer side in the radial direction of the insulating substrate 60 from the longest heater portion 42b. According to this, the heating performance of the plate-shaped heating body 59 can be enhanced as much as possible while reducing the influence of the thermal expansion of the ribbon heater 42.
Since the insulating substrate 60 is made of a composite material using ceramics and mica, a substrate having both the heat resistance of ceramics and the mechanical strength of mica can be formed, and the life of the insulating substrate 60 can be extended.

Since the ceramic plate 62 is disposed on the top plate 13 side of the insulating substrate 60 so as to be in contact with most of the ribbon heater 42, the insulating substrate 60 can be made excellent in heat resistance. On the other hand, by hooking the ribbon heater 42 at the protrusion 67 of the mica plate 63, it is possible to sufficiently resist stress caused by thermal expansion or the like of the ribbon heater 42.
The projecting portion 67 serving as the folded portion has an inclined portion 67a, and the ribbon heater 42 is folded back corresponding to the inclined portion 67a. As a result, the ribbon heater 42 can be folded back without waste so as not to generate a gap in the winding portion 68 and wound so as to be in close contact with the insulating substrate 60 in an appropriate tension state. Therefore, since the adhesiveness of the plate-like heating body 59 to the top plate 13 is increased, the movement of heat from the plate-like heating body 59 to the top plate 13 can be promoted, and the heating efficiency can be increased.

  The grounded lead wire 69 is arranged in the vicinity of the ribbon heater 42 so as to be separated from the ribbon heater 42, and a notification unit 73 serving as a notification means notifies that a current has flowed through the lead wire 69. According to this, even if the top plate 13 breaks or the like and the ribbon heater 42 is splashed with water, this can be notified to the user by the notification unit 73, and safety in use can be improved. In this case, since the heating controller 19 stops energization of the ribbon heater 42, it is possible to prevent leakage and electric shock. In addition, even if the ribbon heater 42 and the conductive wire 69 are in contact with each other due to deterioration of the insulating substrate 60, the notification unit 73 can notify the user, and overall safety is excellent. it can.

  The insulating substrate 60 is composed of a plurality of divided substrates 61 divided in the circumferential direction. According to this, after winding the ribbon heater 42 around the divided substrate 61, the adjacent divided substrates 61 and 61 can be connected to each other, so that the winding operation of the ribbon heater 42 can be simplified. That is, unlike the present embodiment, in the non-divided type insulating substrate (for example, the insulating substrate 41 of the first embodiment), the ribbon heater 42 is wound so as to pass through the relatively narrow hole 43 and slit 44. Although it is troublesome, in the insulating substrate 60 of this embodiment, the other divided substrates 61 do not get in the way when the divided substrates 61 are wound, and the divided substrates 61 can be densely arranged in the circumferential direction (in other words, (If this is done, the portion corresponding to the hole 43 and the slit 44 can be made as narrow as possible), the heating efficiency can be increased. Further, the adjacent divided substrates 61 and 61 can be easily connected by fitting the adjacent engaging convex portions 65 and engaging concave portions 66 together, and the number of assembling steps of the plate-like heating body 59 is reduced. can do.

<Other examples>
In the second embodiment, the grounded lead wire 69 is provided on the upper surface side of the insulating substrate 60, but may be provided on the lower surface side of the divided substrate 61. Here, FIG. 14 is a bottom view of the plate-like heating body 59. As shown in FIG. 14, the conductive wire 69 includes an annular detector 69c annularly arranged on the outer peripheral portion on the lower surface side of the insulating substrate 60, and an annular shape. And an auxiliary detector 69d that protrudes from the detector 69c inward in the circumferential direction at equal intervals. In this regard, the auxiliary detector 69d can be provided to extend to the center side of the insulating substrate 60 by using a space where the ribbon heater 42 is not disposed on the lower surface side of the insulating substrate 60. Accordingly, it is possible to relatively reduce the thermal influence of the ribbon heater 42 on the conducting wire 69 and to detect the abnormality such as the above-described water intrusion from the outer peripheral portion to the central portion of the insulating substrate 60. The conducting wire 69 may be disposed on the upper surface side or the lower surface side of the insulating substrate 41 of the first embodiment.

  In the above embodiment, the ribbon heater 42 is wound so that most of the ribbon heater 42 is located on the surface side of the insulating substrates 41 and 60. However, the ribbon heater 42 is not limited to a so-called single-sided heater. 15 is an enlarged plan view showing a part of the insulating substrate 41. As shown in FIG. 15, the ribbon heater 42 circulates in the fan-shaped portion sandwiched between the hole 43 and the slit 44 in the insulating substrate 41. A so-called double-sided heater wound in such a manner may be used. In FIG. 15, the ribbon heater 42 is wound around the lower surface side of the insulating substrate 41 by a broken line. Similarly, the insulating substrate 60 may be wound around the divided substrate 61 so that the ribbon heater 42 rotates.

  The ribbon heater 42 may be wound with a shorter length than the longest heater portion b on the radially outer side of the insulating substrate from the longest heater portion 42b. That is, for example, the divided substrate 61 may be formed in a drum shape as a whole, and a pair of winding portions may be provided along curved portions on both sides thereof. Further, the present invention is not limited to the built-in type, and can be applied to any cooking device such as a stationary type. In addition, the present invention can be implemented by appropriately changing the number of divisions of the insulating substrate 60 (number of divided substrates 61) within a range not departing from the gist of the present invention.

The top view of the plate-shaped heating body of the induction heating cooking appliance which shows 1st Example of this invention Longitudinal sectional view showing schematic configuration of induction heating cooker Longitudinal sectional view showing the main part of the induction heating cooker Exploded perspective view showing the configuration of the heating unit Block diagram showing electrical configuration of induction heating cooker FIG. 2 is an enlarged view of a folded portion of a plate-like heating body, (a) is a plan view, and (b) is a longitudinal sectional view taken along line X1-X1 in FIG. 6 (a). Schematic diagram showing enlarged main parts of the heating unit It is a schematic diagram for explaining the line length and the central angle of the ribbon heater, (a) is an enlarged plan view of the plate-like heating body, (b) is a diagram in which the relationship between the winding part and the ribbon heater is regarded as a right triangle, (C) is an isosceles triangle FIG. 1 equivalent view showing the second embodiment (A) And (b) is a figure equivalent to FIG. 6, (c) is the schematic which expanded P3 part in FIG. Figure equivalent to FIG. The figure which shows the relation between the input electric power of the ribbon heater at the time of boiling water and the temperature of the ribbon heater (A) And (b) is a figure corresponding to Drawing 8 (a) and (c). Bottom view of a plate-like heating body showing another embodiment The top view which expands and shows a part of plate-shaped heating body

Explanation of symbols

  In the drawings, 10 is an induction heating cooker, 13 is a top plate, 17 is a pan (cooking device to be heated), 21 is an induction heating coil, 22 and 59 are plate-shaped heating bodies, 41 and 60 are insulating substrates, and 42 is a ribbon. Heater (heater), 42a is the shortest heater part, 42b is the longest heater part, 46 and 68 are winding parts, 47 is a folded part, 48 is a protrusion part, 62 is a ceramic plate (ceramics), 63 is a mica plate (mica) , 67 is a protruding portion (folded portion), 67a is an inclined portion (inclined), 69 is a conducting wire (conductor), and 73 is a notifying portion (notifying means).

Claims (10)

A top plate on which the cooker to be heated is placed;
An induction heating coil that is provided below the top plate and that induction-heats the cooked utensil placed on the top plate;
In a cooking device comprising: a plate-like heating body that is disposed between the top plate and the induction heating coil and heats the cooked utensil placed on the top plate,
The plate-like heating body comprises a belt-like heater that generates heat when energized, and a plate-like insulating substrate having a winding part for winding the heater,
A plurality of the winding portions are provided on the insulating substrate so as to extend radially from the center portion thereof, and the interval between the winding portions adjacent in the circumferential direction is set within a predetermined angle.
The heating cooker, wherein the heater is wound so as to be spanned between the winding portions adjacent in the circumferential direction.   The heater has a shortest heater portion in which the winding length between the winding portions is the shortest and a longest heater portion in which the winding length is the longest between the winding portions in the radial direction of the insulating substrate. The cooking device according to claim 1, wherein the cooking device is wound between the winding portions within a predetermined length.   The cooking device according to claim 2, wherein the longest heater portion is at least in the middle of the radial direction of the insulating substrate.   4. The cooking device according to claim 2, wherein the heater is wound with a length equivalent to that of the longest heater portion outside the longest heater portion in the radial direction of the insulating substrate.   The cooking device according to any one of claims 1 to 4, wherein the insulating substrate is made of a composite material using ceramics and mica.   A folded portion is provided in the winding portion, and the heater is folded at the folded portion and provided on the induction heating coil side of the insulating substrate, and the other portion is on the top plate side of the insulating substrate. The cooking device according to any one of claims 1 to 5, wherein the cooking device is provided.   The cooking device according to claim 6, wherein the ceramic is disposed on the top plate side of the insulating substrate so as to be in contact with the other portion of the heater.   The cooking device according to claim 6 or 7, wherein the folded portion has an inclination, and the heater is folded according to the inclination. A conductor that is disposed in the vicinity of the heater, spaced apart from the heater, and grounded;
The cooking device according to claim 1, further comprising notification means for notifying that a current has flowed through the conductor.   The cooking device according to claim 9, wherein the conductor is disposed on an upper surface side or a lower surface side of the insulating substrate.

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