Induction heating cooker

Abstract

To provide an induction heating cooker which can inhibit temperature rise of a heating unit.SOLUTION: An induction heating cooker includes: a housing; a top plate which is provided at an upper part of the housing and on which an object to be heated (a heated object) is placed; a heating unit having a coil substrate stored in the housing, and a coil part formed on the coil substrate as a metallic pattern to heat the heated object; and a blower which sends air to the heating unit. Through holes for passing air sent from the blower are formed in an area, which excludes an area formed with the coil part, of the coil substrate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an induction heating cooker that performs induction heating cooking on an object to be heated. [Background technology]

[0002] Conventionally, induction heating cookers use a heating unit having a coil wound with a conductor to generate a magnetic flux for induction heating. Patent Document 1 discloses a coil that uses a pattern formed on a substrate as the conductor, unlike coils that use Litz wire, which is made by twisting together thin wires, as the conductor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-109314 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a pattern is formed on a substrate, as in the coil shown in Patent Document 1, it is difficult to ensure a sufficient conductor area compared to a coil that uses Litz wire as the conductor wire. This results in a high resistance value for the coil conductor wire, which increases loss and can cause the temperature of the heating part to rise excessively.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an induction heating cooker that can suppress an excessive rise in the temperature of the heating part. [Means for solving the problem]

[0006] The induction heating cooker according to the present disclosure comprises a housing, a top plate provided on top of the housing on which an object to be heated is placed, a coil substrate stored inside the housing, a heating section having a coil portion formed as a metal pattern on the coil substrate and heating the object to be heated, and a blower that sends air to the heating section, and in the area of ​​the coil substrate excluding the area where the coil portion is formed, through holes are formed to allow the air sent from the blower to pass through. [Effects of the Invention]

[0007] According to the induction cooking device of the present disclosure, a through hole is formed in the coil substrate. As a result, the space between the front surface of the coil substrate and the top plate communicates with the space on the back side of the coil substrate via the through hole, increasing the area of ​​the airflow path to the space between the front surface of the coil substrate and the top plate and reducing pressure loss of the cooling air. Therefore, the amount of air flowing through the space between the front surface of the coil substrate and the top plate increases, making it possible to suppress excessive temperature increases in the heating unit. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an exploded perspective view showing an induction heating cooker according to a first embodiment. [Figure 2] 2 is a circuit diagram showing an induction heating circuit section and a control circuit section according to the first embodiment. FIG. [Figure 3] 2 is a perspective view of the heating unit according to the first embodiment as viewed from above. FIG. [Figure 4] FIG. 10 is a perspective view of a heating unit according to a second embodiment as viewed from above. [Figure 5] FIG. 11 is a perspective view of a heating unit according to a third embodiment, as viewed from above. [Figure 6] FIG. 10 is a top view of a heating unit according to a fourth embodiment. [Figure 7] FIG. 11 is a perspective view of a heating unit according to a fifth embodiment when viewed from above. [Figure 8] FIG. 13 is a perspective view of a heating unit according to a sixth embodiment when viewed from above. [Figure 9]FIG. 13 is a top view showing a substrate blower and a coil substrate according to a sixth embodiment. [Figure 10] FIG. 13 is a side view showing a substrate blower and a coil substrate according to a sixth embodiment. [Figure 11] FIG. 13 is a perspective view of a heating unit according to a seventh embodiment, as viewed from above. [Figure 12] FIG. 13 is a perspective view of a heating unit according to a modification of the seventh embodiment, as viewed from above. [Figure 13] FIG. 13 is a perspective view of a heating unit according to an eighth embodiment, as viewed from above. [Figure 14] FIG. 13 is a side view of a heating unit according to an eighth embodiment. [Figure 15] FIG. 13 is a perspective view of a heating unit according to a modification of the eighth embodiment, as viewed from above. [Figure 16] FIG. 13 is a perspective view of a heating unit according to a ninth embodiment, as viewed from above. [Figure 17] FIG. 13 is an enlarged view showing a main part of a heating unit according to a ninth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment 1 1 is an exploded perspective view showing an induction heating cooker 100 according to embodiment 1. The induction heating cooker 100 according to embodiment 1 is a cooking cooker that uses electromagnetic induction to heat a cooking container and food to be heated. In the following description, in the induction heating cooker 100, the direction from the surface on which the food to be heated is placed toward the bottom surface, or the direction from the bottom surface toward the surface on which the food to be heated is placed, is referred to as the up-down direction.

[0010] 1, the induction cooking device 100 includes a housing 1, a top plate 2, a blower 3, a first heating section 10a, a second heating section 10b, a third heating section 10c, and a grill chamber 20. The housing 1 is a case that houses the first heating section 10a, the second heating section 10b, the third heating section 10c, and the grill chamber 20. The housing 1 is hollow and has an open top.

[0011] The top plate 2 is a plate provided above the housing 1 and forms the upper part of the induction cooking appliance 100. An object to be heated is placed on the top plate 2. FIG. 1 shows an example in which a pot P, which is a cooking vessel, is placed as the object to be heated. The top plate 2 is made of a material that transmits infrared rays, such as heat-resistant tempered glass or crystallized glass. A rubber packing or sealant (not shown) is provided between the top plate 2 and the edge of the opening in the housing 1. This allows the top plate 2 to be fixed to the housing 1 with the gap between the top plate 2 and the housing 1 tightly sealed.

[0012] The top plate 2 is formed with first heating port 21a, second heating port 21b, and third heating port 21c as heating ports 21 for induction heating an object to be heated. First heating port 21a, second heating port 21b, and third heating port 21c are heating regions corresponding to first heating section 10a, second heating section 10b, and third heating section 10c, respectively. In other words, first heating section 10a heats the object to be heated (pot P and the food being cooked inside pot P) placed on first heating port 21a. Similarly, second heating section 10b heats the object to be heated placed on second heating port 21b, and third heating section 10c heats the object to be heated placed on third heating port 21c. The first heating outlet 21a, the second heating outlet 21b, and the third heating outlet 21c are shown as circular shapes painted or printed, etc. This shows the user the approximate placement position of the heated object. Hereinafter, when there is no need to distinguish between the first heating outlet 21a, the second heating outlet 21b, and the third heating outlet 21c, they may be referred to as heating outlets 21.

[0013] In Fig. 1, the first heating port 21a and the second heating port 21b are arranged side by side on the front side of the induction cooking device 100, and the third heating port 21c is arranged approximately in the center on the back side of the induction cooking device 100. The arrangement of the heating ports 21 is not limited to this. For example, three heating ports 21 may be arranged horizontally in a straight line. Furthermore, the heating ports 21 may be arranged so that the center of the first heating section 10a and the center of the second heating section 10b are positioned at different depth directions.

[0014] The top plate 2 is provided with a first operating unit 22a, a second operating unit 22b, and a third operating unit 22c. Hereinafter, when the first operating unit 22a, the second operating unit 22b, and the third operating unit 22c are not distinguished from each other, they may be referred to as operating units 22. The operating units 22 are, for example, buttons covered with a flexible cover that are pressed by the user. The first operating unit 22a, the second operating unit 22b, and the third operating unit 22c function as input devices corresponding to the first heating unit 10a, the second heating unit 10b, and the third heating unit 10c, respectively. The first operating unit 22a, the second operating unit 22b, and the third operating unit 22c accept input of setting information such as the input heat (input power) when heating an object to be heated and a cooking menu (water boiling mode, deep frying mode, etc.).

[0015] The top plate 2 is provided with a first display unit 23a, a second display unit 23b, and a third display unit 23c. Hereinafter, when the first display unit 23a, the second display unit 23b, and the third display unit 23c are not distinguished from one another, they may be referred to as display units 23. The display units 23 are, for example, displays. The first display unit 23a, the second display unit 23b, and the third display unit 23c are display devices corresponding to the first heating unit 10a, the second heating unit 10b, and the third heating unit 10c, respectively. The first display unit 23a, the second display unit 23b, and the third display unit 23c display usage status information of the corresponding heating unit 10. Specifically, the usage status information of the heating unit 10 indicates the usage status of the heating unit 10, and the display unit 23 displays whether each heating unit 10 is heating or not, the input heat level, and the cooking menu. The display unit 23 also displays whether each heating unit 10 is operating normally. Furthermore, the display unit 23 displays whether the position of the object to be heated is normal or not. Furthermore, the display unit 23 may display information about the state of wireless communication with an external communication device.

[0016] In the above description, an operation unit 22 and a display unit 23 are provided for each heating port 21. However, an operation unit 22 and a display unit 23 may be provided for each heating port 21. Alternatively, a touch display that serves as both the operation unit 22 and the display unit 23 may be provided.

[0017] The blower 3 is located at the rear of the housing 1. The blower 3 blows air forward. The air blown by the blower 3 comes into contact with the heat-generating components inside the induction cooking appliance 100, promoting heat dissipation from the heat-generating components and cooling the heat-generating components. Hereinafter, the air blown by the blower 3 may be referred to as cooling air. Herein, the heat-generating components include, for example, the first heating unit 10a, the second heating unit 10b, and the third heating unit 10c, as well as the diode bridge 31, the reactor 32, the switching elements 41 and 42, and the resonant capacitor 60 of the induction heating circuit unit 700 (described later). Providing individual heat dissipation fans for all of these components increases the number of components, increases the size of the device, and increases costs. Furthermore, if multiple blowers 3 are provided for the heating unit 10 and cooling air is to be sent from multiple directions, an air path structure may be required to guide air from each blower 3 to the heating unit 10. If an air path structure is provided, pressure loss occurs and some of the generated air may not be used effectively, so it is necessary to increase the rotation speed of the fan 3. Therefore, it is difficult to avoid the generation of noise. For this reason, instead of providing multiple fans 3, a single fan 3 is provided, and the air path structure for guiding air directly from the fan 3 to the heating unit 10 in the housing 1 is omitted.

[0018] The first heating unit 10a, the second heating unit 10b, and the third heating unit 10c are housed below the top plate 2 and inside the housing 1. As described above, the first heating unit 10a, the second heating unit 10b, and the third heating unit 10c heat the objects placed on the corresponding heating ports 21. Hereinafter, when the first heating unit 10a, the second heating unit 10b, and the third heating unit 10c are not distinguished from each other, they may be referred to as heating units 10. As will be described in detail later, the heating units 10 inductively heat the load (the object) by supplying high-frequency power to a coil unit 11 formed as a metal thin film pattern on a coil substrate 14. Note that, for example, the third heating unit 10c may heat the load using a heater rather than induction heating. Although FIG. 1 shows a case where three heating units 10 are provided, the number of heating units 10 is not particularly limited.

[0019] The grill chamber 20 heats the object to be heated stored therein. The grill chamber 20 may heat the object to be heated by a heater, or may heat the object to be heated by induction. When the grill chamber 20 is used to heat the object to be heated by induction, a plate (not shown) into which a coil (not shown) is cast is provided inside the grill chamber 20. When a high-frequency current is supplied to the heating coil, the object to be heated placed on the plate is induction heated.

[0020] An inverter circuit section 40, a DC power supply circuit section 30, and a control circuit section 50 are provided inside the housing 1. The inverter circuit section 40 supplies high-frequency power to the coil section 11 of the heating section 10. The DC power supply circuit section 30 converts AC voltage input from an AC power supply 800 (see FIG. 2) into DC voltage. The control circuit section 50 controls the operation of the entire induction heating cooker 100.

[0021] FIG. 2 is a circuit diagram showing an induction heating circuit section 700 and a control circuit section 50 according to the first embodiment. The induction heating cooker 100 includes the induction heating circuit section 700, the control circuit section 50, an input current sensor 61, an output current sensor 62, and a heated object temperature sensor 63. The induction heating circuit section 700 is connected to a commercial AC power supply 800, rectifies the power supplied from the AC power supply 800, and supplies the power to the coil section 11 of the heating section 10. The induction heating circuit section 700 includes a DC power supply circuit section 30, an inverter circuit section 40, and a resonant capacitor 60. Note that FIG. 2 shows, as an example, only one induction heating circuit section 700 corresponding to the coil section 11 of one heating section 10 (for example, the first heating section 10a). The induction heating circuit section 700 may be provided for each heating section 10, or may be shared by multiple heating sections 10.

[0022] The DC power supply circuit unit 30 converts AC power input from a commercial AC power supply 800 into DC power and outputs it to the inverter circuit unit 40. The DC power supply circuit unit 30 includes a diode bridge 31, a reactor 32, and a smoothing capacitor 33.

[0023] The inverter circuit unit 40 converts the DC power output from the DC power supply circuit unit 30 into AC power with a high frequency of about 20 kHz to 80 kHz and supplies it to a resonant circuit consisting of the coil unit 11 and the resonant capacitor 60. The inverter circuit unit 40 is a so-called half-bridge inverter in which a switching element 41 and a switching element 42 are connected in series to the output of the DC power supply circuit unit 30. A flywheel diode 43 and a flywheel diode 44 are connected in parallel with the switching element 41 and the switching element 42, respectively. The switching element 41 and the switching element 42 are, for example, IGBTs (Insulated Gate Bipolar Transistors), which are silicon-based bipolar semiconductors.

[0024] The configuration of the inverter circuit unit 40 is not limited to the above. The inverter circuit unit 40 may also have a full-bridge configuration, for example, in which four IGBTs and diodes are combined. The switching elements 41 and 42 and the flywheel diodes 43 and 44 may be made of wide-bandgap semiconductor materials such as silicon carbide or gallium nitride materials. Unipolar semiconductors such as MOSFETs (metal-oxide-semiconductor field-effect transistors) or HEMTs (high electron mobility transistors) may also be used.

[0025] By using wide bandgap semiconductors for the switching elements 41 and 42, it is possible to reduce the conduction loss of the switching elements 41 and 42. Furthermore, since the heat dissipation of the induction heating circuit unit 700 is good even when the switching frequency (drive frequency) is set to a high frequency (high speed), it is possible to make the heat dissipation fins (not shown) of the induction heating circuit unit 700 smaller. Therefore, it is possible to reduce the size and cost of the induction heating circuit unit 700.

[0026] The resonant capacitor 60 is connected in series to the coil section 11 to generate current resonance. The resonant circuit consisting of the coil section 11 and the resonant capacitor 60 has a resonant frequency that corresponds to the inductance of the coil section 11 and the capacitance of the resonant capacitor 60. When the coil section 11 is magnetically coupled to an object to be heated, which is a metal load for the coil section 11, the inductance of the coil section 11 changes according to the characteristics of the metal load. The resonant frequency of the resonant circuit changes according to the change in inductance of the coil section 11. Note that the resonant capacitor 60 and the coil section 11 may be connected in parallel to generate voltage resonance.

[0027] As described above, by configuring the induction heating circuit section 700, a high-frequency current of about several tens of amperes flows through the coil section 11. As a result, a high-frequency magnetic flux generated by the high-frequency current generates an eddy current in the object to be heated placed on the top plate 2 directly above the coil section 11, and the object to be heated is induction heated.

[0028] The input current sensor 61 detects, for example, the current input to the DC power supply circuit unit 30 from a commercial AC power source 800, and outputs a voltage signal corresponding to the input current value to the control circuit unit 50. The output current sensor 62 is connected to a resonant circuit consisting of the coil unit 11 and a resonant capacitor 60. The output current sensor 62 detects the current flowing through the coil unit 11 using, for example, a current transformer, and outputs a voltage signal corresponding to the output current value to the coil unit 11 to the control circuit unit 50. As an alternative to a current transformer, a current sensor using a Hall element or a resistor for current measurement may also be used. The heated object temperature sensor 63 is, for example, an infrared sensor that detects the temperature of the heated object and transmits a voltage signal corresponding to the temperature of the heated object to the control circuit unit 50.

[0029] Connection terminals 12 and 13 are provided between the coil section 11 and the inverter circuit section 40. The coil section 11 and the inverter circuit section 40 are connected using lead wires (not shown). The connection terminals 12 and 13 are used to secure the lead wires connecting the coil section 11 and the inverter circuit section 40. The connection terminals 12 and 13 are, for example, tab terminals. The lead wires may be secured to the terminal blocks of the connection terminals 12 and 13 by screws or by soldering grommets. The connection terminals 12 and 13 of the first embodiment are provided on a substrate on which the inverter circuit section 40 is provided, and lead wires extending from both ends of the coil section 11 are secured thereto.

[0030] The control circuit unit 50 includes a calculation unit 51, an inverter control unit 52, and a display / operation unit 53. The calculation unit 51 determines the magnitude of power to be output to the load based on voltage signals input from the input current sensor 61, the output current sensor 62, and the heated object temperature sensor 63, as well as setting information input from the operation unit 22. The calculation unit 51 then instructs the inverter control unit 52 to generate a switching signal corresponding to the magnitude of power to be output to the load. The inverter control unit 52 generates switching signals to operate each switching element 41 based on the command from the calculation unit 51, and transmits the switching signals to the inverter circuit unit 40. The display / operation unit 53 controls the content to be displayed on the display unit 23. The display / operation unit 53 also transmits setting information input from the operation unit 22 to the calculation unit 51.

[0031] Fig. 3 is a perspective view of the heating unit 10 according to the first embodiment as seen from above. As shown in Fig. 3, the heating unit 10 has a coil unit 11 and a coil substrate 14. In the following description, with reference to a state in which the induction heating cooker 100 is installed, the surface of the coil substrate 14, which is a plate-shaped member, facing the upper side (top plate side) is referred to as a front surface 141, and the surface opposite to the front surface 141 is referred to as a back surface 142. However, the back surface 142 is not shown in the first embodiment, and is shown in Fig. 6 corresponding to the fourth embodiment.

[0032] As shown in FIG. 3, the coil portion 11 is formed by spirally winding a pattern of a thin metal film such as copper. The coil portion 11 has a generally circular shape. The coil portion 11 is wound at equal intervals to form an outer appearance consisting of multiple concentric circles. Here, the portion of the pattern wound one full turn with its starting and ending ends offset in the radial direction is referred to as a winding portion 80. The coil portion 11 is made up of multiple winding portions 80. The space between two winding portions 80 of the coil substrate 14 is referred to as a circumferential portion 143. The coil portion 11 may have a polygonal or flattened general shape to match the shape of the heating port 21 or the object to be heated.

[0033] The coil portion 11 is formed on the front surface 141 of the coil substrate 14. Alternatively, the coil portion 11 may be formed on both sides of the coil substrate 14, with the pattern on the front surface 141 connected to the pattern on the back surface 142. In this case, the conductor area of ​​the heating portion 10 is increased, which increases the cross-sectional area of ​​the conductor and reduces copper loss. Therefore, the power loss generated in the winding of the coil portion 11 is reduced.

[0034] The coil substrate 14 is a printed circuit board made of an insulating material. The base material of the coil substrate 14 is selected from glass epoxy resin, composite epoxy resin such as CEM3, paper epoxy, or paper phenol, etc. Although a method of depositing a metal film that will become the coil portion 11 on glass or a bakelite material can also be used, the former method requires less time to form the copper pattern. Furthermore, it is relatively easy to use widely used processing methods. The shape of the coil substrate 14 may be selected depending on the shape of the coil portion 11, etc. For example, the coil substrate 14 may be rectangular or circular.

[0035] A first through hole 171 and a second through hole 172 are formed in the coil substrate 14. The first through hole 171 is formed in the circumferential portion 143, i.e., between the two winding portions 80. The first through hole 171 is a circular opening that penetrates the coil substrate 14 and allows cooling air to pass through. The multiple first through holes 171 are positioned so as to be aligned in a straight line. For the sake of explanation, the multiple first through holes 171 aligned in a straight line will be referred to as a through hole group 171X. Four through hole groups 171X are formed in the coil substrate 14. Adjacent through hole groups 171X are spaced apart by 90° in the circumferential direction of the coil portion 11.

[0036] Here, to explain the position of the first through hole 171 in the first embodiment, it is assumed that the coil portion 11 includes an inner circumferential portion 81 including the inner end portion and an outer circumferential portion 82 including the outer end portion and located outside the inner circumferential portion 81. For example, the inner circumferential portion 81 and the outer circumferential portion 82 are separated at the center in the radial direction of the coil portion 11 so that the number of winding portions 80 constituting the inner circumferential portion 81 is the same as or differs by only one from the number of winding portions 80 constituting the outer circumferential portion 82. In the following description, when referring to a circumferential portion 143 corresponding to the inner circumferential portion 81, it refers to the circumferential portion 143 located between the winding portions 80 constituting the inner circumferential portion 81. Similarly, when referring to a circumferential portion 143 corresponding to the outer circumferential portion 82, it refers to the circumferential portion 143 between the outermost winding portion 80 constituting the inner circumferential portion 81 and the outer circumferential portion 82, or the circumferential portion 143 located between the winding portions 80 constituting the outer circumferential portion 82.

[0037] A larger number of first through holes 171 of the heating unit 10 are formed in an inner peripheral region of the coil unit 11 of the coil substrate 14 (i.e., a region where the inner peripheral portion 81 is formed) than in an outer peripheral region of the coil unit 11 of the coil substrate 14 (i.e., a region where the outer peripheral portion 82 is located). Specifically, first through holes 171 are formed in all of the circumferential portions 143 corresponding to the inner peripheral portion 81, whereas first through holes 171 are formed every other circumferential portion 143 corresponding to the outer peripheral portion 82. In other words, the ratio of the number of first through holes 171 formed in the circumferential portions 143 corresponding to the inner peripheral portion 81 of the coil unit 11 to the number of circumferential portions 143 corresponding to the inner peripheral portion 81 of the coil unit 11 is greater than the ratio of the number of first through holes 171 formed in the circumferential portions 143 corresponding to the outer peripheral portion 82 of the coil unit 11 to the number of circumferential portions 143 corresponding to the outer peripheral portion 82 of the coil unit 11.

[0038] The second through hole 172 is formed in the center of the coil portion 11. The second through hole 172 is a circular opening that penetrates the coil substrate 14, and allows cooling air to pass through. Four second through holes 172 are formed in the coil substrate 14. The diameter of the second through holes 172 is larger than that of the first through holes 171.

[0039] In order to bring the coil unit 11 close to the pan, which is the object to be heated, and to increase the power efficiency of induction heating, the heating unit 10 is provided close to the top plate 2. The heating unit 10 is also provided so that the direction in which the surface of the coil substrate 14 extends is parallel to the direction of air blown from the blower 3.

[0040] The effects of the first embodiment will be described. First, the issues that arise when a pattern formed on the coil substrate 14 is used as a conductor will be described. For induction heating, a current of several amperes flows through the coil portion 11 at a high frequency of several tens of kilohertz. At this time, copper loss occurs due to the resistance component of the coil portion 11. In addition, eddy currents are generated in the coil portion 11 by magnetic flux generated by the high-frequency current, resulting in eddy current loss. These losses cause the coil portion 11 to heat up, raising the temperature of the coil substrate 14. When glass epoxy resin is used as the material for the coil substrate 14, the temperature of the coil substrate 14 must be kept below the heat-resistant temperature of the resin. Furthermore, the heat generated by the coil portion 11 also raises the temperature of electronic components arranged around the heating portion 10 inside the housing of the induction cooking appliance 100. The temperature of the electronic components must be kept below the rated temperature at which they can operate, or below a temperature at which the product's lifespan is not significantly reduced.

[0041] If the first through-holes 171 and the second through-holes 172 were not provided, the air from the blower 3 could only be blown to the surface 141 of the coil substrate 14 of the heating unit 10 through the gaps between the top plate 2 and the ends of the four sides of the coil substrate 14. In other words, the gaps between the ends of the coil substrate 14 of the heating unit 10 and the top plate 2 would be the only airflow path. Therefore, if the first through-holes 171 and the second through-holes 172 were not provided, the cooling air from the blower 3 would not be able to effectively cool the coil substrate 14 and electronic components. In particular, the heating unit 10 is configured so that the direction in which the surface of the coil substrate 14 extends is parallel to the direction of airflow from the blower 3. Therefore, the cooling air from the blower 3 cannot be uniformly applied to the surface of the coil substrate 14 of the heating unit 10. Furthermore, the center of the heating unit 10 is far from the ends of the coil substrate 14 that take in the cooling air, making the air flow prone to stagnation. Therefore, the temperatures of the coil unit 11 and the coil substrate 14 tend to be higher in the central areas.

[0042] In contrast, according to the first embodiment, the coil substrate 14 is formed with the first through hole 171 and the second through hole 172. As a result, the space between the front surface 141 of the coil substrate 14 and the top plate 2 communicates with the space on the back surface 142 side of the coil substrate 14 via the first through hole 171 and the second through hole 172, increasing the area of ​​the airflow path to the space between the front surface 141 of the coil substrate 14 and the top plate 2 and reducing pressure loss of the cooling air. Therefore, the amount of air flowing through the space between the front surface 141 of the coil substrate 14 and the top plate 2 increases, making it possible to suppress an excessive rise in the temperature of the heating unit 10.

[0043] Furthermore, according to the first embodiment, a second through hole 172 is provided in the center of the coil substrate 14, and the diameter of the second through hole 172 is larger than the diameter of the first through hole 171. This reduces the pressure loss of the cooling air that is sent directly to the center of the heating unit 10, where heat tends to build up and the temperature tends to rise. This further suppresses an excessive rise in the temperature of the heating unit 10.

[0044] Moreover, by suppressing an excessive rise in the temperature of the heating unit 10, the failure rate of electronic components can be reduced.

[0045] Furthermore, according to the first embodiment, it is possible to suppress an increase in the cost of components for constructing an air path, since there is no air path structure for guiding cooling air directly to the heating unit 10. In addition, when an air path structure is provided, pressure loss occurs, and some of the generated air may not be effectively utilized, but this can be suppressed.

[0046] Furthermore, according to the first embodiment, the ratio between the number of circumferential portions 143 corresponding to the inner circumferential portion 81 of the coil portion 11 and the number of first through holes 171 is greater than the ratio between the number of circumferential portions 143 corresponding to the outer circumferential portion 82 of the coil portion 11 and the number of first through holes 171. This further reduces the pressure loss of the cooling air that is sent directly to the center of the heating portion 10, where heat tends to build up and the temperature tends to rise. This further suppresses excessive temperature rise in the heating portion 10.

[0047] Embodiment 2 Fig. 4 is a perspective view of the heating unit 10A according to the second embodiment when viewed from above. As shown in Fig. 4, in the heating unit 10A of the second embodiment as well, the first through-hole 171 is formed in the circumferential portion 143 between the two winding portions 80. However, the heating unit 10A of the second embodiment differs from that of the first embodiment in the position where the first through-hole 171 is formed. The following description will focus on the differences from the first embodiment, and the same reference numerals will be used for components having the same functions, and the same description will be omitted.

[0048] Here, to explain the position where the first through hole 171 is formed in the second embodiment, it is assumed that the coil portion 11 includes an inner circumferential portion 83 including the inner circumferential end, an outer circumferential portion 84 including the outer circumferential end, and an intermediate portion 85 located between the inner circumferential portion 83 and the outer circumferential portion 84. For example, the intermediate portion 85 is made up of a plurality of winding portions 80 including a central winding portion 80 and winding portions 80 located inside and outside the central winding portion 80. Furthermore, the inner circumferential portion 83 is made up of the winding portions 80 that are, among the plurality of winding portions 80, more inward than the winding portions 80 that constitute the intermediate portion 85. Similarly, the outer circumferential portion 84 is made up of the winding portions 80 that are, among the plurality of winding portions 80, more outward than the winding portions 80 that constitute the intermediate portion 85. As a specific example of how to divide the inner circumferential portion 83, the outer circumferential portion 84, and the intermediate portion 85, the number of winding portions 80 constituting the inner circumferential portion 83, the number of winding portions 80 constituting the outer circumferential portion 84, and the number of winding portions 80 constituting the intermediate portion 85 are the same or differ by only one among them. In the following description, when referring to a circumferential portion 143 corresponding to the inner circumferential portion 83, it means the circumferential portion 143 located between the winding portions 80 constituting the inner circumferential portion 83. When referring to a circumferential portion 143 corresponding to the intermediate portion 85, it means the circumferential portion 143 between the outermost winding portion 80 constituting the inner circumferential portion 83 and the winding portion 80 constituting the intermediate portion 85, the circumferential portion 143 between the innermost winding portion 80 constituting the outer circumferential portion 84 and the winding portion 80 constituting the intermediate portion 85, or the portion between the winding portions 80 constituting the intermediate portion 85. Furthermore, when referring to the circumferential portion 143 corresponding to the outer peripheral portion 84, it means the circumferential portion 143 located between the winding portions 80 that make up the outer peripheral portion 84.

[0049] The heating unit 10A has more first through holes 171 formed in the region of the coil substrate 14 where the inner circumferential portion 83 of the coil unit 11 is formed than in the region of the coil substrate 14 where the intermediate portion 85 of the coil unit 11 is located. Specifically, first through holes 171 are formed in all of the circumferential portions 143 corresponding to the inner circumferential portions 83, whereas first through holes 171 are formed in every other circumferential portion 143 corresponding to the intermediate portion 85. In other words, the ratio of the number of first through holes 171 formed in the circumferential portions 143 corresponding to the inner circumferential portions 83 of the coil unit 11 to the number of circumferential portions 143 corresponding to the inner circumferential portions 83 of the coil unit 11 is greater than the ratio of the number of first through holes 171 formed in the circumferential portions 143 corresponding to the intermediate portions 85 of the coil unit 11 to the number of circumferential portions 143 corresponding to the intermediate portions 85 of the coil unit 11.

[0050] Similarly, more first through holes 171 of the heating unit 10A are formed in the region of the coil substrate 14 where the outer circumferential portion 84 of the coil unit 11 is formed than in the region of the coil substrate 14 where the intermediate portion 85 of the coil unit 11 is located. Specifically, first through holes 171 are formed in all of the circumferential portions 143 corresponding to the outer circumferential portions 84, whereas first through holes 171 are formed in every other circumferential portion 143 corresponding to the intermediate portion 85. In other words, the ratio of the number of first through holes 171 formed in the circumferential portions 143 corresponding to the outer circumferential portion 84 of the coil unit 11 to the number of circumferential portions 143 corresponding to the outer circumferential portion 84 of the coil unit 11 is greater than the ratio of the number of first through holes 171 formed in the circumferential portions 143 corresponding to the intermediate portion 85 of the coil unit 11 to the number of circumferential portions 143 corresponding to the intermediate portion 85 of the coil unit 11.

[0051] It is generally known that, among the losses occurring in the coil portion 11, the magnitude of the loss due to eddy currents varies depending on the surrounding magnetic flux density. In particular, in the middle of the coil portion 11, current flows in a direction that cancels out the magnetic flux of adjacent windings. Therefore, the magnetic flux density in the middle portion 85 of the coil portion 11 is lower than the magnetic flux density in the inner peripheral portion 83 and outer peripheral portion 84 of the coil portion 11. For this reason, the loss due to eddy currents is relatively large near the inner peripheral portion 83 and outer peripheral portion 84 of the coil portion 11, and the temperature tends to rise.

[0052] According to the second embodiment, the ratio between the number of circumferential portions 143 corresponding to the inner circumferential portion 83 and the outer circumferential portion 84 of the coil portion 11 and the number of first through holes 171 is greater than the ratio between the number of circumferential portions 143 corresponding to the intermediate portion 85 of the coil portion 11 and the number of first through holes 171. This further reduces the pressure loss of the cooling air that is sent directly to the vicinity of the inner circumferential portion 83 and the outer circumferential portion 84, where loss due to eddy currents in the coil portion 11 is large and the temperature is likely to rise. This further suppresses excessive temperature rise in the heating portion 10A.

[0053] Note that, regardless of the positional relationship with the coil unit 11, the heat dissipation performance of the heating unit 10 can be improved by forming a larger number of first through holes 171. However, in this case, the strength of the coil substrate 14 decreases, and there is a risk that the coil substrate 14 may crack due to vibrations and stresses applied during transportation or installation of the product. For this reason, as shown in the second embodiment, by increasing the number of first through holes 171 in the circumferential portion 143 corresponding to the inner circumferential portion 83 and the outer circumferential portion 84 of the coil unit 11, where loss due to eddy currents is large and temperature is likely to rise, and by decreasing the number of first through holes 171 in the circumferential portion 143 corresponding to the intermediate portion 85 of the coil unit 11, it is possible to suppress a decrease in the strength of the coil substrate 14 while suppressing an excessive rise in temperature of the heating unit 10.

[0054] Embodiment 3 Fig. 5 is a perspective view of a heating unit 10B according to embodiment 3 as seen from above. As shown in Fig. 5, heating unit 10B according to embodiment 3 differs from embodiments 1 and 2 in that the number of first through holes 171 is changed between the upstream side and the downstream side of the air sent from blower 3. The arrows in Fig. 5 indicate the direction of flow of air sent from blower 3. The following description will focus on the differences from embodiments 1 and 2, and components having the same functions will be designated by the same reference numerals, and the same description will be omitted.

[0055] More first through holes 171 of heating unit 10B are formed in an upstream region of coil substrate 14 of the air sent from fan 3 than in a downstream region of coil substrate 14 of the air sent from fan 3. In other words, in coil substrate 14, the number of first through holes 171 included in through hole group 171X located upstream of the cooling air is greater than the number of first through holes 171 included in through hole group 171X located downstream of the cooling air.

[0056] According to the third embodiment, more first through holes 171 are formed in the region of coil substrate 14 upstream of the air sent from fan 3 than in the region of coil substrate 14 downstream of the air sent from fan 3. In particular, on the upstream side where the flow velocity of the cooling air is high, a large opening area for circulating the cooling air is ensured, which efficiently reduces pressure loss in the airflow path. This increases the amount of cooling air flowing over surface 141 of coil substrate 14, and prevents an excessive rise in the temperature of heating unit 10B.

[0057] Furthermore, as explained in the first embodiment, in order to suppress an increase in the number of parts and an increase in the pressure loss of the cooling air, the third embodiment is configured to include only one blower 3. One method of promoting cooling of the heating unit 10B using a single blower 3 is to increase the rotation speed of the blower 3 to increase the air volume, but this raises concerns about increased noise. In contrast, according to the third embodiment, the air volume of the cooling air flowing over the surface 141 of the coil substrate 14 can be increased without increasing the rotation speed of the blower 3. Therefore, according to the third embodiment, the generation of noise can be suppressed.

[0058] Embodiment 4 Fig. 6 is a top view of a heating unit 10C according to embodiment 4. As shown in Fig. 6, the heating unit 10C of embodiment 4 differs from embodiment 1 in that the first through-holes 171 are arranged along the magnetic body 15. The following description will focus on the differences from embodiment 1, and components having the same functions will be given the same reference numerals, and the same description will be omitted.

[0059] The magnetic body 15 is provided on the rear surface 142 of the coil substrate 14. The magnetic body 15 is arranged along the radial direction of the coil substrate 14. The magnetic body 15 induces the magnetic flux generated in the coil portion 11 to the load. Iron loss due to the magnetic flux for induction heating also occurs in the magnetic body 15. As a result, the magnetic body 15 generates heat. At this time, the coil portion 11 near the magnetic body 15 is easily affected by the heat generated by the magnetic body 15 and its temperature tends to rise.

[0060] The first through holes 171 are arranged along the magnetic bodies 15. Specifically, one through hole group 171X is formed along one side of one magnetic body 15. Therefore, according to the fourth embodiment, the amount of cooling air flowing over the surface 141 of the coil substrate 14 can be increased particularly in the region of the coil portion 11 where the temperature is likely to rise due to heat generated by the magnetic bodies 15, thereby suppressing an excessive rise in the temperature of the heating portion 10C.

[0061] Embodiment 5 Fig. 7 is a perspective view of a heating unit 10D according to embodiment 5 when viewed from above. As shown in Fig. 7, the heating unit 10D of embodiment 5 differs from embodiment 1 in that it has a heated object temperature sensor 63 and a third through hole 173 formed between the heated object temperature sensor 63 and the end of the coil unit 11. The following description will focus on the differences from embodiment 1, and components having the same functions will be designated by the same reference numerals, and the same description will be omitted.

[0062] In the fifth embodiment, the object temperature sensor 63 is provided on the coil substrate 14. The object temperature sensor 63 includes a sensor element 631 and a load temperature detection circuit 632. The object temperature sensor 63 is mounted near the coil unit 11, which is the heat source, to detect the temperature of the pan, which is the load. The object temperature sensor 63 may include a connector for connecting an electric wire that transmits and receives signals input and output to and from the load temperature detection circuit 632, or power for operating the load temperature detection circuit 632. The object temperature sensor 63 is provided inside the coil unit 11, that is, closer to the center of the coil unit 11 than the innermost periphery of the coil unit 11 wound on the mounting surface of the coil substrate 14. The object temperature sensor 63 may also be provided outside the outermost periphery of the coil unit 11.

[0063] The sensor element 631 is mounted on the surface 141 of the coil substrate 14 to detect the temperature of the object to be heated. The object temperature sensor 63 is, for example, a thermopile-type infrared sensor, and the sensor element 631 detects the temperature by receiving infrared rays emitted by the object to be heated. A voltage signal including the temperature of the object to be heated detected by the sensor element 631 is transmitted to the load temperature detection circuit 632. The sensor element 631 may also be a thermistor that is brought into contact with the baking sheet 2 and detects the temperature of heat transferred from the pan through the baking sheet 2.

[0064] The load temperature detection circuit 632 is mounted on the rear surface 142 of the coil substrate 14. In FIG. 7, the load temperature detection circuit 632 provided on the rear surface 142 is indicated by a dashed line. The load temperature detection circuit 632 performs processes such as amplification, noise removal, and A / D conversion on the voltage signal output by the sensor element 631. The load temperature detection circuit 632 transmits a voltage signal indicating the temperature of the heated object after processing to the calculation unit 51 of the control circuit unit 50. The load temperature detection circuit 632 has a resistor-based voltage divider circuit, an amplifier for signal amplification, a filter for noise removal, an A / D converter, etc. to process the voltage signal output by the sensor element 631.

[0065] The coil substrate 14 does not allow the coil section 11 to be formed in the location where the sensor element 631 and the load temperature detection circuit 632 are mounted. By mounting the sensor element 631 on the front surface 141 of the coil substrate 14 and the load temperature detection circuit 632 on the back surface 142 of the coil substrate 14, the object temperature sensor 63 can be housed inside the coil section 11. This eliminates the need to shape the coil section 11 formed on the front surface 141 of the coil substrate 14 so as to bypass the sensor element 631 or the load temperature detection circuit 632. In other words, the coil section 11 is uniformly formed on the front surface 141 of the coil substrate 14. This prevents the coil substrate 14 from having areas with and without the coil section 11, which would result in different temperatures depending on the heating location of the object. This improves the usability of the induction heating cooker 100.

[0066] The third through hole 173 is formed between the object temperature sensor 63 and the innermost winding portion 80 of the coil portion 11. The third through hole 173 is a rectangular opening that penetrates the coil substrate 14. The third through hole 173 is adjacent to the inner end of the coil portion 11 in the circumferential direction. This reduces the amount of heat conducted from the coil portion 11 to the object temperature sensor 63 via the coil substrate 14. Therefore, even if the temperature of the coil portion 11 rises due to induction heating, an excessive rise in the temperature of the object temperature sensor 63 due to heat conduction from the coil portion 11 can be suppressed.

[0067] The plurality of third through holes 173 may be formed to surround the heated object temperature sensor 63. In this case, the heated object temperature sensor 63 is affected by heat conduction from the coil section 11 from all around, but the amount of heat conducted from the coil section 11 to the heated object temperature sensor 63 via the coil substrate 14 can be further reduced. This makes it possible to further suppress an excessive rise in the temperature of the heated object temperature sensor 63 due to heat conduction from the coil section 11. However, it is sufficient that the third through holes 173 are provided in at least a portion of the periphery of the heated object temperature sensor 63.

[0068] Furthermore, the shape of the third through hole 173 does not have to be rectangular. For example, it may be circular like the second through hole 172. Furthermore, if the opening area is the same, forming a plurality of third through holes 173 can prevent the strength of the coil substrate 14 from decreasing.

[0069] As described above, the object temperature sensor 63 is mounted near the coil 11, which is the heat source. Therefore, when the coil 11 generates heat, the temperature of the load temperature detection circuit 632 also rises. At this time, the characteristics of the circuit change depending on the temperature characteristics of the components used in the load temperature detection circuit 632, degrading the accuracy of detecting the temperature of the object. Therefore, heat must be dissipated so that the components of the load temperature detection circuit 632 remain below their rated temperature. However, electronic components using semiconductors generally have a lower rated temperature than coil substrates 14 made of glass epoxy or the like. Therefore, when the object temperature sensor 63 is provided on the coil substrate 14, it is necessary to prioritize suppressing the thermal effects on the object temperature sensor 63.

[0070] According to the fifth embodiment, the third through-hole 173 is provided between the object temperature sensor 63 and the coil section 11, thereby reducing the amount of heat conducted from the coil section 11 to the object temperature sensor 63 via the coil substrate 14. Therefore, even if the temperature of the coil section 11 rises during induction heating operation, an excessive rise in the temperature of the object temperature sensor 63 due to heat conduction from the coil section 11 can be suppressed.

[0071] Another method for promoting cooling of heating unit 10D is to increase the rotation speed of blower 3 to increase the airflow, but this raises concerns about increased noise. According to embodiment 5, the airflow rate of cooling air flowing over surface 141 of coil substrate 14 can be increased without increasing the rotation speed of blower 3. Therefore, according to embodiment 5, noise generation can be suppressed.

[0072] Embodiment 6 Fig. 8 is a perspective view of a heating unit 10E according to embodiment 6 as seen from above. As shown in Fig. 8, heating unit 10E according to embodiment 6 differs from embodiment 2 in that it includes substrate blower 16. The following description will focus on the differences from embodiment 2, and components having the same functions will be designated by the same reference numerals, and the same description will be omitted.

[0073] The heating unit 10E of the sixth embodiment has a board fan 16 instead of the fan 3. The board fan 16 is, for example, a sirocco fan. The board fan 16 is directly attached to the coil board 14. The board fan 16 is provided on each of the coil boards 14 of the multiple heating units 10E.

[0074] A specific method for attaching the board blower 16 will now be described. An insertion hole 18 is formed in the coil board 14. The insertion hole 18 is an opening formed by penetrating the coil board 14. The insertion holes 18 are formed at least in a portion of the coil board 14 outside the outer periphery of the coil portion 11, specifically, two insertion holes 18 are formed on the edge of the coil board 14.

[0075] FIG. 9 is a top view showing board blower 16 and coil substrate 14 according to embodiment 6. FIG. 10 is a side view showing board blower 16 and coil substrate 14 according to embodiment 6. FIG. 10 corresponds to a cross-sectional view taken along line AA in FIG. 9. As shown in FIGS. 9 and 10, board blower 16 has front-side outlet 161 and rear-side outlet 162 for blowing out air, arm portions 163 formed on both sides of front-side outlet 161 and rear-side outlet 162, and insertion portions 164 protruding upward from each arm portion 163. Board blower 16 is fixed to coil substrate 14 by inserting two insertion portions 164 into two insertion holes 18.

[0076] The thickness of arm portion 163 is set so that when insertion portion 164 is inserted into insertion hole 18 until back surface 142 of coil substrate 14 contacts the upper surface of arm portion 163, the lower end of front-side air outlet 161 is positioned above front surface 141 of coil substrate 14 and the upper end of back-side air outlet 162 is positioned below back surface 142 of coil substrate 14. As a result, air blown out from front-side air outlet 161 of board blower 16 flows onto front surface 141 of coil substrate 14, and air blown out from back-side air outlet 162 flows onto back surface 142 of coil substrate 14.

[0077] According to the sixth embodiment, air can be directly supplied to both sides of the coil substrate 14. This makes it possible to suppress a rise in the temperature of the heating unit 10E.

[0078] Furthermore, according to the sixth embodiment, there is no air passage structure for directly guiding cooling air from the blower 3 to each heating unit 10E, so it is possible to suppress an increase in the cost of components for constructing the air passage. In addition, when an air passage structure is provided, pressure loss occurs, and some of the generated air may not be effectively utilized, but this can be suppressed.

[0079] Furthermore, according to the sixth embodiment, air can be directly supplied to the coil substrate 14 of each heating section 10E, so there is no need to increase the amount of air blown, and noise generation can be suppressed.

[0080] Furthermore, according to the sixth embodiment, simply by inserting the insertion portion 164 into the insertion hole 18, the board blower 16 can be fixed in a position where it can blow air to both sides of the coil board 14, and therefore no frame is required to position the board blower 16 on the coil board 14. This prevents the number of structural parts from increasing and the size of the heating unit 10E from becoming larger.

[0081] The structure of board blower 16 is not particularly limited as long as it can blow air to both sides of coil board 14. For example, board blower 16 may have a single air outlet, and be provided so that coil board 14 is located between the upper and lower ends of the outlet.

[0082] Embodiment 7 Fig. 11 is a perspective view of a heating unit 10F according to embodiment 7 when viewed from above. As shown in Fig. 11, the heating unit 10F according to embodiment 7 differs from embodiment 1 in that it has a fourth through hole 174 instead of the first through hole 171 and the second through hole 172. The following description will focus on the differences from embodiment 1, and components having the same functions will be designated by the same reference numerals, and the same description will be omitted.

[0083] A plurality of fourth through holes 174 are formed in a portion of coil substrate 14 that is at least outside the outer periphery of coil portion 11, specifically on the edge of coil substrate 14. Fourth through holes 174 are rectangular openings that penetrate coil substrate 14. Fourth through holes 174 allow cooling air to circulate between coil substrate 14 and top plate 2. The long side direction of fourth through hole 174's rectangular shape coincides with the flow direction of cooling air sent from blower 3.

[0084] According to the seventh embodiment, by forming the fourth through holes 174, the amount of air sent to the surface 141 of the coil substrate 14 is increased, thereby suppressing an excessive rise in the temperature of the coil portion 11 and the coil substrate 14. In particular, because the fourth through holes 174 are formed upstream of the coil portion 11 in the direction of the cooling air, the cooling air sent to the surface 141 of the coil substrate 14 can come into contact with the entire coil portion 11. Therefore, the rise in the temperature of the heating unit 10F can be efficiently suppressed.

[0085] Furthermore, according to the seventh embodiment, by aligning the long side direction of the fourth through-hole 174 with the direction in which the cooling air flows, it is possible to suppress pressure loss to the cooling air and to suppress turbulence of the cooling air. Therefore, a decrease in the flow rate of the cooling air is suppressed, and an excessive rise in the temperature of the heating unit 10F can be further reduced.

[0086] Furthermore, when the first through holes 171 are provided in the peripheral portion 143 of the coil substrate 14, the size or pattern width of the first through holes 171 is limited. For example, by increasing the diameter of the first through holes 171, it is possible to reduce pressure loss to the cooling air and improve heat dissipation of the heating unit 10F, but depending on the size of the first through holes 171, it may be necessary to narrow the pattern width of the coil portion 11. The narrower the pattern width of the coil portion 11, the greater the copper loss.

[0087] In contrast to this, by forming the fourth through holes 174 outside the outermost periphery of the coil portion 11, it is possible to set the size of the fourth through holes 174 regardless of the width of the pattern. Therefore, by ensuring that the fourth through holes 174 are large, it is possible to improve heat dissipation from the heating portion 10F and suppress an increase in copper loss due to a thinner pattern.

[0088] (Modification of the seventh embodiment) FIG. 12 is a perspective view of a heating unit 10G according to a modification of the seventh embodiment, viewed from above. As shown in FIG. 12, slits 19 may be formed in a portion of the coil substrate 14 that is at least outside the outer periphery of the coil portion 11, specifically, in the edge portion of the coil substrate 14 on the downstream side of the cooling air. Multiple slits 19 are formed in the coil substrate 14. The slits 19 are not surrounded by the coil substrate 14, but are open at the end on the downstream side of the cooling air. In other words, the coil substrate 14 has a shape in which multiple projections and recesses are formed on the edge portion on the downstream side. Note that FIG. 12 omits the fourth through hole 174.

[0089] Generally, when an induction cooking device 100 uses a heating unit in which a coil portion 11 is formed by a pattern on a coil substrate 14, wind noise may be generated when cooling air passes over the end of the coil substrate 14. The wind noise may be heard as noise by the user during cooking and may cause discomfort. While the wind noise can be suppressed by reducing the airflow rate of the blower 3, this reduces the heat dissipation performance of the heating unit, making it necessary to limit the input heat power to suppress heat generation in the heating unit. For this reason, generally, when an induction cooking device 100 uses a heating unit 10G in which a coil portion 11 is formed by a pattern on a coil substrate 14, there is a trade-off between heating performance and noise.

[0090] In the modified example of the seventh embodiment, slits 19 are formed in coil substrate 14, thereby generating turbulence in the cooling air after it has passed through coil portion 11. This reduces the wind noise that occurs when the cooling air passes through coil substrate 14. Therefore, by allowing the required amount of cooling air to flow through heating portion 10G and dissipating heat, it is possible to maintain heating performance and reduce noise, thereby improving usability in cooking.

[0091] Embodiment 8 Fig. 13 is a perspective view of a heating unit 10H according to embodiment 8 when viewed from above. Fig. 14 is a side view of the heating unit 10H according to embodiment 8. As shown in Figs. 13 and 14, the heating unit 10H according to embodiment 8 differs from embodiment 1 in that it has fifth through holes 175 and sixth through holes 176 instead of the first through holes 171 and second through holes 172, and also has first air guide sections 71 and second air guide sections 72. The following description will focus on the differences from embodiment 1, and components having the same functions will be designated by the same reference numerals, and the same descriptions will be omitted.

[0092] The fifth through hole 175 is formed inside the innermost periphery of the coil portion 11. The fifth through hole 175 is a circular opening that penetrates the coil substrate 14, and allows cooling air to pass through. The fifth through hole 175 is formed by punching the coil substrate 14. The diameter of the fifth through hole 175 is larger than that of the second through hole 172 described in the first embodiment.

[0093] The sixth through hole 176 is formed outside the outermost periphery of the coil portion 11. The sixth through hole 176 is an opening that penetrates the coil substrate 14 and allows cooling air to pass through. The sixth through hole 176 is formed in an arc shape so as to follow the outer periphery of the coil portion 11.

[0094] The first airflow guide section 71 is disposed directly below the fifth through-hole 175. The first airflow guide section 71 has an overall arc-like shape and is disposed so that the bulge of the arc faces the fan 3. The first airflow guide section 71 has a slanted side 71a formed on the surface facing the fan 3. The slanted side 71a is formed so as to be oblique with respect to the direction of airflow from the fan 3. Specifically, the slanted side 71a is formed so that the length of the upper arc is shorter than the length of the lower arc. The arc shape of the lower end of the first airflow guide section 71 roughly corresponds to a portion of the circumference of the fifth through-hole 175 being cut away. The cooling air sent from the fan 3 hits the slanted side 71a of the first airflow guide section 71 and flows upward, thereby guiding the air to the fifth through-hole 175. The position at which the first airflow guide section 71 is fixed is not particularly limited. For example, the first airflow guide section 71 may be provided on a frame that fixes the heating section 10H to the housing 1.

[0095] The second air guide section 72 is disposed directly below the sixth through hole 176. The second air guide section 72 has an overall arc-like shape, with the bulge of the arc facing the fan 3. The second air guide section 72 has a slant side 72a formed on the surface facing the fan 3. The slant side 72a is formed obliquely with respect to the direction of air blown from the fan 3. Specifically, the slant side 72a is formed so that the length of the upper arc is shorter than the length of the lower arc. The arc shape of the lower end of the second air guide section 72 roughly corresponds to a portion of the circumference of the sixth through hole 176 being cut away. The cooling air sent from the fan 3 hits the slant side 72a of the second air guide section 72 and flows upward, thereby guiding the air to the sixth through hole 176. The position at which the second air guide section 72 is fixed is not particularly limited. For example, the second air guide section 72 may be provided on a frame that fixes the heating section 10H to the housing 1.

[0096] According to the eighth embodiment, the fifth through hole 175 and the sixth through hole 176 are formed. As a result, the space between the top plate 2 and the front surface 141 of the coil substrate 14 communicates with the space on the back surface 142 side of the coil substrate 14 via the fifth through hole 175 and the sixth through hole 176. This increases the area of ​​the airflow path to the space between the top plate 2 and the front surface 141 of the coil substrate 14, reducing pressure loss of the cooling air. This increases the amount of air flowing through the space between the top plate 2 and the front surface 141 of the coil substrate 14, making it possible to suppress an excessive rise in the temperature of the heating unit 10.

[0097] It is generally known that, among the losses occurring in the coil portion 11, the magnitude of the loss due to eddy currents varies depending on the surrounding magnetic flux density. In particular, in the middle of the coil portion 11, current flows in a direction that cancels out the magnetic flux of adjacent windings. Therefore, the magnetic flux density in the middle of the coil portion 11 is lower than that in the inner and outer peripheral portions of the coil portion 11. For this reason, the loss due to eddy currents is relatively large near the inner and outer peripheral portions of the coil portion 11, and the temperature tends to rise.

[0098] According to the eighth embodiment, the fifth through hole 175 is formed inside the innermost periphery of the coil portion 11, and the sixth through hole 176 is formed outside the outermost periphery of the coil portion 11. This makes it possible to more effectively dissipate heat near the inner and outer peripheries of the coil portion 11, where loss is large and temperature tends to rise.

[0099] Furthermore, when the first through holes 171 are provided in the peripheral portion 143 of the coil substrate 14, the size or pattern width of the first through holes 171 is limited. For example, by increasing the diameter of the first through holes 171, it is possible to reduce pressure loss in the cooling air and improve heat dissipation of the heating unit 10H, but depending on the size of the first through holes 171, it may be necessary to narrow the pattern width of the coil portion 11. The narrower the pattern width of the coil portion 11, the greater the copper loss.

[0100] In contrast to this, by forming the sixth through holes 176 outside the outermost periphery of the coil portion 11, it is possible to set the size of the sixth through holes 176 regardless of the width of the pattern. Therefore, by ensuring that the sixth through holes 176 are large, it is possible to improve heat dissipation from the heating portion 10H and suppress an increase in copper loss due to a thinner pattern.

[0101] (Modification of the eighth embodiment) 15 is a perspective view of a heating unit 10I according to a modification of the eighth embodiment, as viewed from above. As shown in FIG. 15, when the coil unit 11 has a first coil unit 111 and a second coil unit 112 provided on the outer periphery of the first coil unit 111, a seventh through hole 177 may be formed between the first coil unit 111 and the second coil unit 112. The seventh through hole 177 is an opening that penetrates the coil substrate 14, and allows cooling air to pass through. The seventh through hole 177 is formed in an arc shape so as to follow the outer periphery of the first coil unit 111 and the inner periphery of the second coil unit 112.

[0102] The first coil portion 111 and the second coil portion 112 are configured to receive high-frequency power from separate inverters and be individually controlled. The first coil portion 111 and the second coil portion 112 may be connected in series or parallel to a single inverter. The first coil portion 111 and the second coil portion 112 have opposite current flow directions. For example, if current flows from the outside to the inside of the first coil portion 111, current flows from the inside to the outside of the second coil portion 112. It is generally known that magnetic flux concentrates in the inner periphery of the coil portion 11, causing uneven heating. However, by dividing the coil portion 11 into the first coil portion 111 and the second coil portion 112 and reversing the current direction, magnetic flux also concentrates between the first coil portion 111 and the second coil portion 112, thereby reducing uneven heating.

[0103] In the configuration of the modified example of the eighth embodiment, the magnetic flux density is high on the inner periphery of the first coil portion 111, on the outer periphery of the second coil portion 112, and between the first coil portion 111 and the second coil portion 112, causing relatively large losses due to eddy currents and facilitating a temperature rise. Here, in the modified example of the eighth embodiment, in addition to the fifth through hole 175 and the sixth through hole 176, a seventh through hole 177 is formed between the first coil portion 111 and the second coil portion 112. This allows for efficient heat dissipation in the inner periphery of the first coil portion 111, the outer periphery of the second coil portion 112, and the vicinity between the first coil portion 111 and the second coil portion 112, where losses are large and temperatures tend to rise.

[0104] Embodiment 9 FIG. 16 is a perspective view of the heating unit 10J according to the ninth embodiment as viewed from above. FIG. 17 is an enlarged view showing the main parts of the heating unit 10J according to the ninth embodiment. FIG. 17 shows an enlarged view of the end part on the center side of the heating unit 10J. As shown in FIGS. 16 and 17, the heating unit 10J according to the ninth embodiment differs from the first embodiment in that the coil part 90 is branched. The following description will focus on the differences from the first embodiment, and the same reference numerals will be used for components having the same functions, and the same description will be omitted.

[0105] The coil portion 90 has a first branch portion 91 and a second branch portion 92 formed by radially branching the winding portion 80. Specifically, the innermost winding portion 80 and the outermost winding portion 80 of the coil portion 90 branch radially, and the innermost of the two branch ends of the innermost winding portion 80 is connected to the innermost of the two branch ends of the outermost winding portion 80 by the first branch portion 91 extending in a spiral shape. Similarly, the outermost of the two branch ends of the innermost winding portion 80 is connected to the outermost of the two branch ends of the outermost winding portion 80 by the second branch portion 92 extending in a spiral shape. The first branch portion 91 and the second branch portion 92 extend parallel to each other. The eighth through hole 178 is formed between the first branch portion 91 and the second branch portion 92. It is generally known that increasing the cross-sectional area of ​​a pattern can reduce copper loss, while increasing the pattern width increases loss due to eddy currents. In contrast, by dividing the pattern in parallel, it is possible to increase the cross-sectional area while suppressing the increase in the pattern width itself. As a result, it is possible to reduce copper loss while suppressing the increase in eddy currents.

[0106] According to the ninth embodiment, by forming eighth through hole 178 in coil substrate 14 between first branch portion 91 and second branch portion 92, the space between front surface 141 of coil substrate 14 and top plate 2 and the space on the back surface 142 side of coil substrate 14 are connected via eighth through hole 178. This increases the area of ​​the airflow path to the space between front surface 141 of coil substrate 14 and top plate 2, reducing pressure loss of the cooling air. This increases the amount of air flowing through the space between front surface 141 of coil substrate 14 and top plate 2, making it possible to suppress an excessive rise in the temperature of heating unit 10.

[0107] The above is a description of the embodiments of the present disclosure, but the present disclosure is not limited to the configurations of the above embodiments and various modifications are possible within the scope of the technical concept. For example, the first through hole 171 to the eighth through hole 178 may be formed in combinations other than those described in each embodiment, as long as the condition that the formation locations do not overlap is satisfied. As an example, the fourth through hole 174 described in embodiment 7 may also be formed in the heating units of embodiments 1 to 6. Furthermore, the slit 19 described in the modified example of embodiment 7 may be formed in heating units other than those of embodiment 7.

[0108] Furthermore, in the first to sixth embodiments, the first through holes 171 are described as being arranged in a straight line, but the first through holes 171 do not have to be arranged in a straight line. The strength of the coil substrate 14 is increased when the first through holes 171 are arranged circumferentially offset rather than arranged in a straight line. Furthermore, in the first to sixth embodiments, when there are multiple pairs of first through holes 171 formed in a certain peripheral portion 143 and first through holes 171 formed in a peripheral portion 143 adjacent to that peripheral portion 143, the angles between the first through holes 171 in each pair may not be uniform across all pairs, but may be narrower in a region of the coil substrate 14 upstream of the air blown from the fan 3 than in a region of the coil substrate 14 downstream of the air blown from the fan 3. In other words, the more adjacent first through holes 171 are formed upstream of the air flow, the more adjacent first through holes 171 may be formed. This allows cooler cooling air to flow through the space between the top plate 2 and the surface 141 of the coil substrate 14. Of the four through-hole groups 171X shown in the first to sixth embodiments, the first through-holes 171 may be arranged in a non-linear manner in any one to three of them (i.e., no through-hole group 171X is formed), or the first through-holes 171 may be arranged in a non-linear manner in all of the four through-hole groups 171X.

[0109] Furthermore, in the fifth embodiment, the object temperature sensor 63 is described as being provided inside the coil portion 11, but it may be provided between the two winding portions 80 of the coil portion 11. Furthermore, in a configuration in which the coil portion 11 has a first coil portion 111 and a second coil portion 112 provided on the outer periphery of the first coil portion 111, as in the modified example of the eighth embodiment, when the object temperature sensor 63 is provided, it may be provided between the first coil portion 111 and the second coil portion 112.

[0110] The first through hole 171 to the eighth through hole 178 are formed in the area of ​​the coil substrate 14 excluding the area where the coil portion 11 is formed, and correspond to the "through hole" in the present disclosure.

[0111] Various aspects of the present disclosure are summarized below as appendices.

[0112] (Appendix 1) The housing and A top plate provided on the upper part of the housing and on which an object to be heated is placed; a heating unit including a coil substrate housed inside the housing and a coil portion formed as a metal pattern on the coil substrate and configured to heat the object to be heated; a blower that sends air to the heating unit, In the area of ​​the coil substrate excluding the area where the coil portion is formed, through holes are formed to allow the air sent from the blower to pass through. Induction heating cooker. (Appendix 2) The coil portion is made up of a plurality of winding portions, The winding portion is formed by winding the pattern once so that the start and end of the pattern are offset in the radial direction, The coil substrate has a first through hole formed therein, the first through hole being located between the two winding portions. 10. An induction cooker according to claim 1. (Appendix 3) The coil substrate has a second through hole formed therein that is positioned inside the coil portion. 1. An induction cooker according to claim 2. (Appendix 4) The number of the first through holes formed in the region on the inner periphery side of the coil portion is greater than the number of the first through holes formed in the region on the outer periphery side of the coil portion. 4. An induction heating cooker according to claim 2 or 3. (Appendix 5) The coil portion An inner periphery; an intermediate portion located on the outer circumferential side of the inner circumferential portion and including the centrally located winding portion among the plurality of winding portions; and an outer peripheral portion located on the outer peripheral side of the intermediate portion, the number of the first through holes formed in the region corresponding to the inner circumferential portion is greater than the number of the first through holes formed in the region corresponding to the intermediate portion, The number of the first through holes formed in the region corresponding to the outer periphery side is greater than the number of the first through holes formed in the region corresponding to the intermediate portion. 4. An induction heating cooker according to claim 2 or 3. (Appendix 6) The number of the first through holes formed on the windward side of the air sent from the blower is greater than the number of the first through holes formed on the leeward side of the air sent from the blower. An induction heating cooker according to any one of appendices 2 to 5. (Appendix 7) the heating unit has a magnetic body extending in a radial direction, The first through hole is formed along the magnetic body. 7. An induction heating cooker according to any one of appendices 2 to 6. (Appendix 8) a temperature sensor for detecting the temperature of the object to be heated; The coil substrate has a third through hole formed therein, the third through hole being located between the temperature sensor for the object to be heated and the coil portion. An induction heating cooker according to any one of appendices 1 to 7. (Appendix 9) The fan is a substrate fan provided on the coil substrate. An induction heating cooker according to any one of appendices 1 to 8. (Appendix 10) The coil substrate has a fourth through hole formed therein as the through hole, the fourth through hole being located outside the coil portion and having a rectangular shape with its long side aligned along the air blowing direction of the fan. 10. An induction heating cooker according to any one of appendices 1 to 9. (Appendix 11) A slit is formed on the edge of the coil substrate on the leeward side of the air sent from the blower. An induction heating cooker according to any one of appendices 1 to 10. (Appendix 12) The coil substrate has a fifth through hole formed therein as the through hole, the fifth through hole being located outside the coil portion and having an arc shape along the outer periphery of the coil portion. 12. An induction heating cooker according to any one of appendices 1 to 11. (Appendix 13) a sixth through hole located inside the coil portion is formed in the coil substrate as the through hole; The induction cooker is a first air guide section that guides air to the fifth through hole; a second air guide section that guides air to the sixth through hole, The first airflow guide section and the second airflow guide section have oblique sides formed obliquely with respect to the airflow direction of the blower. 13. The induction cooker according to claim 12. (Appendix 14) the coil portion has a first coil portion and a second coil portion provided on the outer circumferential side of the first coil portion, The coil substrate has a seventh through hole located between the first coil portion and the second coil portion. 14. The induction heating cooker according to claim 12 or 13. (Appendix 15) The coil portion is made up of a plurality of winding portions, The winding portion is formed by winding the pattern once so that the start and end of the pattern are offset in the radial direction, the coil portion has a first branch portion and a second branch portion branched in a radial direction from the winding portion, The coil substrate has an eighth through hole located between the first branch portion and the second branch portion. An induction heating cooker according to any one of appendices 1 to 14. [Explanation of symbols]

[0113] REFERENCE SIGNS LIST 1 Housing, 2 Top plate, 3 Fan, 10, 10A to 10J Heating section, 10a First heating section, 10b Second heating section, 10c Third heating section, 11 Coil section, 12 Connection terminal, 13 Connection terminal, 14 Coil board, 15 Magnetic material, 16 Board fan, 18 Insertion hole, 19 Slit, 20 Grill chamber, 21 Heating port, 21a First heating port, 21b Second heating port, 21c Third heating port, 22 Operation section, 22a First operation section, 22b Second operation section, 22c Third operation section, 23 Display section, 23a First display section, 23b Second display section, 23c Third display section, 30 DC power supply circuit section, 31 Diode bridge, 32 Reactor, 33 Smoothing capacitor, 40 Inverter circuit section, 41 Switching element, 42 Switching element, 43 flywheel diode, 44 flywheel diode, 50 control circuit section, 51 calculation section, 52 inverter control section, 53 display operation section, 60 resonance capacitor, 61 input current sensor, 62 output current sensor, 63 heated object temperature sensor, 71 first air guide section, 71a oblique side section, 72 second air guide section, 72a oblique side section, 80 winding section, 81 inner periphery section, 82 outer periphery section, 83 inner periphery section, 84 outer periphery section, 85 middle section, 90 coil section, 91 first branch section, 92 second branch section, 100 induction heating cooker, 111 first coil section, 112 second coil section, 141 front surface, 142 back surface, 143 peripheral section, 161 front air outlet, 162 back air outlet, 163 arm section, 164 insertion section, 171 First through hole, 171X through hole group, 172 second through hole, 173 third through hole, 174 fourth through hole, 175 fifth through hole, 176 sixth through hole, 177 seventh through hole, 178 eighth through hole, 631 sensor element, 632 load temperature detection circuit, 700 induction heating circuit section, 800 AC power supply.

Claims

1. The housing and A top plate provided on the upper part of the housing on which an object to be heated is placed; a heating unit including a coil substrate housed inside the housing and a coil portion formed as a metal pattern on the coil substrate and configured to heat the object to be heated; a blower that sends air to the heating unit, In the area of ​​the coil substrate excluding the area where the coil portion is formed, through holes are formed to allow the air sent from the blower to pass through. Induction heating cooker.

2. The coil portion is made up of a plurality of winding portions, The winding portion is formed by winding the pattern once so that a starting end and an ending end are shifted in a radial direction, The coil substrate has a first through hole formed therein, the first through hole being located between the two winding portions. The induction heating cooker according to claim 1 .

3. The coil substrate has a second through hole formed therein that is positioned inside the coil portion. The induction heating cooker according to claim 2.

4. The number of the first through holes formed in the inner peripheral region of the coil portion is greater than the number of the first through holes formed in the outer peripheral region of the coil portion.

4. The induction heating cooker according to claim 2 or 3.

5. The coil portion An inner periphery; an intermediate portion located on the outer circumferential side of the inner circumferential portion and including the centrally located winding portion among the plurality of winding portions; and an outer peripheral portion located on the outer peripheral side of the intermediate portion, the number of the first through holes formed in the region corresponding to the inner periphery is greater than the number of the first through holes formed in the region corresponding to the intermediate portion, The number of the first through holes formed in the region corresponding to the outer periphery side is greater than the number of the first through holes formed in the region corresponding to the intermediate portion.

4. The induction heating cooker according to claim 2 or 3.

6. The number of the first through holes formed on the windward side of the air sent from the blower is greater than the number of the first through holes formed on the leeward side of the air sent from the blower.

4. The induction heating cooker according to claim 2 or 3.

7. the heating unit has a magnetic body extending in a radial direction, The first through hole is formed along the magnetic body.

4. The induction heating cooker according to claim 2 or 3.

8. a temperature sensor for detecting the temperature of the object to be heated; The coil substrate has a third through hole formed therein, the third through hole being located between the temperature sensor for the heated object and the coil portion. The induction heating cooker according to any one of claims 1 to 3.

9. The fan is a substrate fan provided on the coil substrate. The induction heating cooker according to any one of claims 1 to 3.

10. The coil substrate has a fourth through hole formed therein as the through hole, the fourth through hole being located outside the coil portion and having a rectangular shape with its long side aligned along the air blowing direction of the fan. The induction heating cooker according to any one of claims 1 to 3.

11. A slit is formed on the edge of the coil substrate on the leeward side of the air sent from the blower. The induction heating cooker according to claim 10.

12. The coil substrate has a fifth through hole formed therein as the through hole, the fifth through hole being located outside the coil portion and having an arc shape along the outer periphery of the coil portion. The induction heating cooker according to claim 1 .

13. a sixth through hole located inside the coil portion is formed in the coil substrate as the through hole, The induction cooker is a first air guide section that guides air to the fifth through hole; a second air guide section that guides air to the sixth through hole, The first airflow guide section and the second airflow guide section have oblique sides formed obliquely with respect to the airflow direction of the blower. The induction heating cooker according to claim 12.

14. the coil portion includes a first coil portion and a second coil portion provided on an outer circumferential side of the first coil portion, The coil substrate has a seventh through hole formed therein, the seventh through hole being located between the first coil portion and the second coil portion. The induction heating cooker according to claim 12 or 13.

15. The coil portion is made up of a plurality of winding portions, The winding portion is formed by winding the pattern once so that a starting end and an ending end are shifted in a radial direction, the coil portion has a first branch portion and a second branch portion, the first branch portion being branched in a radial direction from the winding portion, The coil substrate has an eighth through hole formed therein, the through hole being located between the first branch portion and the second branch portion. The induction heating cooker according to claim 1 .

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