JP5558295B2 - rice cooker - Google Patents

Description

  The present invention relates to a rice cooker provided with a fire spread prevention member for preventing damage expansion when a problem occurs in a power supply board.

  In the conventional rice cooker, there is one that covers a power supply board on which a semiconductor switching element or a diode bridge having a large calorific value is mounted with a fire spread prevention member, and cools it by sending cooling air into the fire spread prevention member with a cooling fan ( For example, see Patent Document 1).

JP 2008-55089 A (FIG. 1)

  In the conventional rice cooker described above, the cooling air is sent into the fire spread prevention member. Therefore, when a problem occurs in the power supply board, there is a risk that the cooling air may increase the damage.

  The present invention has been made to solve the above-described problems. Even if a problem occurs in the power supply board, it suppresses the expansion of the damage, and a semiconductor switching element or a diode bridge rectifier circuit that generates a large amount of heat. A rice cooker that can be cooled is provided.

The rice cooker according to the present invention has an intake port and an exhaust port, a main body in which the cooking container is detachably accommodated, and an induction heating that is disposed in the main body and heats the cooking container in which the object to be cooked is stored. And an inverter circuit that rectifies the AC power of the commercial power supply and converts the output of the rectifier circuit into AC power of a predetermined frequency and supplies it to the induction heating means by turning on / off at least one semiconductor switching element. A power supply board, a heat dissipating member attached to the power supply board and having a semiconductor switching element of a rectifier circuit and an inverter circuit attached to the surface facing the power supply board, and a box having an opening on one side, the opening being is closed by a heat radiating member from inside and a fire-preventing member is power board are housed, self between the inlet and outlet by the difference between the temperature and the outside temperature in the body during cooking The cooling air convection, the surface of the heat radiating member exposed from the opening of the fire prevention member is cooled.

  According to the present invention, since the fire spread prevention member having a heat dissipation function of the rectifier circuit and the semiconductor switching element mounted on the power supply substrate is provided, the rectifier circuit and the semiconductor switching element can be provided without supplying cooling air into the fire spread prevention member. Can be cooled. In addition, since it is not necessary to provide an inlet and an exhaust port in the fire spread prevention member, it is possible to prevent the damage from being expanded when a problem occurs in the power supply board, and to improve safety.

It is sectional drawing of the rice cooker in Embodiment 1. FIG. It is a block diagram which shows the circuit structure of the rice cooker in Embodiment 1. FIG. It is sectional drawing which expands and shows the fire spread prevention member shown in FIG. It is sectional drawing of the rice cooker in Embodiment 2. FIG. It is a block diagram which shows the circuit structure of the rice cooker in Embodiment 2.

Embodiment 1 FIG.
1 is a cross-sectional view of the rice cooker in the first embodiment, FIG. 2 is a block diagram showing a circuit configuration of the rice cooker in the first embodiment, and FIG. 3 is an enlarged cross-sectional view of the fire spread prevention member shown in FIG. is there.
The rice cooker of Embodiment 1 includes a rice cooker body 1 with an upper opening, an inner pot 2 of a cooking container that is detachably accommodated in the rice cooker body 1, and a hinge provided on the upper back side of the rice cooker body 1. The outer lid 4 is attached to the portion 3 so as to be freely opened and closed, and the inner lid 5 is detachably attached to the back surface of the outer lid 4 and seals the opening of the inner hook 2.

  The rice cooker main body 1 is provided with a substantially cylindrical metal side frame 6 with a body heater attached to the outer surface, and a heating coil 8 which is an induction heating means on the lower surface and the corner of the side frame 6. A substantially deep dish-shaped bottom frame 7 provided, a temperature sensor 9 provided at substantially the center of the bottom frame 7 for detecting the temperature of the inner pot 2 by contacting the bottom surface of the inner pot 2, and the rice cooker body 1 A cord reel 10 installed on the bottom plate 11 and a fire spread prevention member 20 provided in the rear part of the rice cooker body 1 and containing a power supply substrate 21 are provided.

  A first air inlet 13 is provided in a portion of the bottom plate 11 of the rice cooker body 1 that is substantially opposite to the lower part of the fire spread prevention member 20, and a second air inlet 14 is provided in the lower part of the front surface of the rice cooker body 1. Moreover, the exhaust port 15 is provided in the part located above the upper part of the fire spread prevention member 20 among the back surfaces of the rice cooker main body 1. FIG. The outer lid 4 and the inner lid 5 are detachably mounted with a cartridge 16 that discharges steam generated when the food in the inner pot 2 is heated to the outside.

  For example, an operation panel (not shown) is provided on the front surface of the outer lid 4, and a control board 40 is provided on the back surface thereof. As shown in FIG. 2, the control board 40 includes a control unit 41, an input unit 42 that outputs a signal to the control unit 41 in response to an operation from the operation panel, and a time and an operating state based on a signal from the control unit 41. Is mounted on the liquid crystal screen of the operation panel.

  The fire spread prevention member 20 described above is formed in a rectangular box shape by sheet metal, for example, as shown in FIG. On the substantially upper side and both side surfaces of the front surface of the fire spread prevention member 20 on the heating coil 8 side, irregularities 20a are formed that are arranged laterally in the longitudinal direction. The unevenness 20a is provided in order to reinforce the expansion and strength of the surface area of the fire spread prevention member 20. Further, a flat and rectangular opening 20b is provided in the lower part of the front surface of the fire spread prevention member 20. The opening 20b is a hole for exposing the top 31a of the heat dissipation member 31 from the inside. Thus, the fire spread prevention member 20 is configured with the top portion 31a of the heat dissipation member 31 as a part of the front surface.

  The power supply substrate 21 accommodated in the fire spread prevention member 20 is fixed to a resin substrate holder 30 having heat resistance. The power supply substrate 21 includes a rectifier circuit 22 composed of a diode bridge, a choke coil 23 and a smoothing capacitor 24 constituting a smoothing circuit, a resonant capacitor 25 connected in parallel to the heating coil 8, for example, a semiconductor switching element 26a composed of one IGBT. A diode 26b connected in parallel in the reverse direction to the semiconductor switching element 26a, a power supply circuit 27, a drive circuit 28 for turning on and off the semiconductor switching element 26a, and the like are mounted (see FIG. 2). Although the semiconductor switching element 26a is described as not including the diode 26b, a semiconductor switching element in which the semiconductor switching element 26a and the diode 26b are packaged may be used.

  The heat dissipation member 31 is formed in a gate shape when viewed from the longitudinal direction of the fire spread prevention member 20, and both sides thereof are fixed to the power supply substrate 21 by screws 32. The heat dissipating member 31 is fixed to the front surface of the fire spread prevention member 20 with screws 34 so that the top portion 31a is exposed from the opening 20b of the fire spread prevention member 20. That is, the opening 20 b is blocked by the heat radiating member 31. For example, the rectifier circuit 22 is directly attached to the recessed surface of the heat radiating member 31, that is, the surface opposite to the top portion 31 a of the heat radiating member 31 by screws 33, and the semiconductor switching element 26 a is made of silicon having high thermal conductivity. It attaches with the screw | thread 33 through the insulating sheet 35 of this.

  The rectifier circuit 22 and the semiconductor switching element 26 a are fixed by soldering to the power supply substrate 21 after the heat dissipation member 31 is fixed to the power supply substrate 21. Accordingly, when the rectifier circuit 22 and the semiconductor switching element 26a are fixed or when the power supply substrate 21 is handled, the soldered portions of the rectifier circuit 22 and the semiconductor switching element 26a are not stressed, and the connection reliability with the power supply substrate 21 is improved. Will improve.

  In the present embodiment, the rectifier circuit 22, the semiconductor switching element 26a, and the diode 26b are made of a wide band gap semiconductor made of silicon carbide, a gallium nitride material, or diamond. With the wide band gap semiconductor, it is possible to use the rectifier circuit 22 or the semiconductor switching element 26a that generates a small amount of heat, has a high heat-resistant temperature, and can reduce heat loss by 70% as compared with the prior art.

  In the rice cooker configured as described above, when the rice cooking operation is performed by the operation panel, the control unit 41 displays information on the rice cooking operation on the liquid crystal screen through the display unit 43 according to the operation, and a drive circuit. 28 is controlled to turn on and off the semiconductor switching element 26a of the inverter circuit 26. By turning on and off the semiconductor switching element 26a, the power converted into direct current by the rectifier circuit 22, the choke coil 23 and the smoothing capacitor 24 is converted into alternating current power of a predetermined frequency and supplied to the heating coil 8, and the inner pot 2 is Induction heating.

  When the temperature in the rice cooker body 1 increases due to the heating, the air in the rice cooker body 1 rises due to the difference from the outside air temperature, and is discharged to the outside through the exhaust port 15. At this time, the outside air is attracted as cooling air from the first air inlet 13 and the second air inlet 14 into the rice cooker body 1 by the air flow. The induced cooling air rises while cooling the surface of the fire spread prevention member 20 and the heating coil 8 as shown by the arrows in FIG. 1 and is discharged to the outside from the exhaust port 15. The flow of the air (cooling air) is continued until the difference between the temperature in the rice cooker body 1 and the outside air temperature becomes almost the same.

As described above, in the first embodiment, the following effects are obtained.
(1) The fire spread prevention member 20 is formed in a rectangular box shape, an opening 20b is provided on the lower side of the front surface thereof, and the top portion 31a of the heat dissipation member 31 is exposed from the opening 20b to form a part of the front surface of the fire spread prevention member 20. Furthermore, the radiating member 31 is attached with a rectifier circuit 22 and a semiconductor switching element 26a made of a wide band gap semiconductor. Thereby, the rectifier circuit 22 and the semiconductor switching element 26a can be cooled without supplying cooling air into the fire spread prevention member 20. In addition, since the fire spread prevention member 20 is not provided with an intake port and an exhaust port, it is possible to prevent an increase in damage when a problem occurs in the power supply substrate 21 and to improve safety.
(2) As described above, the heat loss can be reduced by 70% of the conventional rectifier circuit 22 and the semiconductor switching element 26a by using a wide band gap semiconductor with a small heat generation amount and a high heat-resistant temperature. The temperature rise of the semiconductor switching element 26a can be reduced, and a sufficient margin can be provided for the temperature limit. Moreover, since it is not necessary to use a large heat radiating fin for the heat radiating member 31 with the effect, the power supply substrate 21 can be made thin, and the fire spread preventing member 20 itself can be miniaturized.
(3) Since the rectifier circuit 22 and the semiconductor switching element 26a are arranged on the first intake port 13 side, the heat radiated from the heat radiating member 31 can be cooled by cooling air having a lower temperature. Further, since the cooling air flows upward together with the heat radiated from the fire spread prevention member 20, the temperature rise of other circuit elements can be reduced.
(4) By insulating the fire spread prevention member 20 from the semiconductor switching element 26a, the necessary insulation distance between the internal wiring and other live parts is reduced, and the configuration of the rice cooker body 1 can be facilitated. it can.
(5) Since the top part 31a of the heat radiating member 31 attached to the fire spread prevention member 20 is arranged on the heating coil 8 side, the heat radiating member 31 can be cooled by the cooling air having a fast flow due to high temperature.

  In the first embodiment, it has been described that the rectifier circuit 22 and the semiconductor switching element 26a are configured by a wide band gap semiconductor. However, either one may be configured by a wide band gap semiconductor.

  Further, the semiconductor switching element 26a is attached to the heat radiating member 31 via the insulating sheet 35 so as to be electrically insulated from the fire spread prevention member 20, but the rectifier circuit 22 is also attached to the heat radiating member 31 via the insulating sheet. May be. Thereby, a required insulation distance between internal wiring and other live parts can be further reduced, and the configuration of the rice cooker body 1 can be facilitated.

  In the first embodiment, it is described that the rectifier circuit 22 and the semiconductor switching element 26a are attached to the heat dissipation member 31, but the present invention is not limited to this. For example, the surface of the rectifier circuit 22 and the semiconductor switching element 26a opposite to the power supply substrate 21 may be attached in close contact with the inner surface of the fire spread prevention member 20. In that case, if the insulating sheet 35 is interposed between the fire spread prevention member 20 and electrically insulated, the semiconductor switching element 26a is interposed via liquid silicon (thermal diffusion compound) having better thermal conductivity than the insulating sheet 35. Therefore, the temperature increase of the semiconductor switching element 26a can be more efficiently suppressed.

Embodiment 2. FIG.
In the first embodiment, the fire spread prevention member 20 and the heating coil 8 are cooled by natural convection of cooling air, but in the second embodiment, the fire spread prevention member 20 and the heating coil 8 are cooled by a cooling fan. It is a thing.
FIG. 4 is a cross-sectional view of the rice cooker in the second embodiment, and FIG. 5 is a block diagram showing a circuit configuration of the rice cooker in the second embodiment. In addition, the same code | symbol is attached | subjected to the part similar to Embodiment 1. FIG.

  As shown in FIG. 4, the rice cooker in the second embodiment is provided with an intake port 13 at a portion of the bottom plate 11 of the rice cooker body 1 that is substantially opposite to the lower part of the fire spread prevention member 20, and the front surface of the rice cooker body 1. An exhaust port 15 is provided in the lower part of the. A cooling fan 51 is installed between the lower part of the fire spread prevention member 20 and the air inlet 13. As shown in FIG. 5, the cooling fan 51 is connected to a cooling fan drive circuit 50 controlled by the control unit 41.

  When the cooling fan 51 is driven by the cooling fan drive circuit 50, as shown by the arrows in FIG. 4, outside air flows from the intake port 13 as cooling air and is sent upward while cooling the surface of the fire spread prevention member 20. , Flows toward the exhaust port 15 side. Further, the cooling air flowing in from the intake port 13 is sent to the heating coil 8 side and is discharged from the exhaust port 15 while cooling the heating coil 8 and the cord reel 10.

As described above, in the second embodiment, the following effects are obtained.
(1) The top portion 31a of the heat dissipation member 31 attached to the rectifier circuit 22 and the semiconductor switching element 26a made of a wide band gap semiconductor is made a part of the front surface of the rectangular box-shaped fire spread prevention member 20, and the fire spread prevention member 20 The surface is cooled by a cooling fan 51. Thereby, the temperature rise of the rectifier circuit 22 and the semiconductor switching element 26a can be more efficiently suppressed without supplying cooling air into the fire spread prevention member 20. In addition, since the fire spread prevention member 20 is not provided with an intake port and an exhaust port, it is possible to prevent an increase in damage when a problem occurs in the power supply substrate 21 and to improve safety.
(2) As described above, the heat loss can be reduced by 70% of the conventional rectifier circuit 22 and the semiconductor switching element 26a by using a wide band gap semiconductor with a small heat generation amount and a high heat-resistant temperature. The temperature rise of the semiconductor switching element 26a can be reduced, and a sufficient margin can be provided for the temperature limit. Moreover, since it is not necessary to use a large heat radiating fin for the heat radiating member 31 with the effect, the power supply substrate 21 can be made thin, and the fire spread preventing member 20 itself can be miniaturized.
(3) Since the rectifier circuit 22 and the semiconductor switching element 26a are arranged on the cooling fan 51 side, the heat radiated from the heat radiating member 31 can be cooled more efficiently by the cooling air having a lower temperature.
(4) By insulating the fire spread prevention member 20 from the semiconductor switching element 26a, the necessary insulation distance between the internal wiring and other live parts is reduced, and the configuration of the rice cooker body 1 can be facilitated. it can.

  In the second embodiment, it has been described that the rectifier circuit 22 and the semiconductor switching element 26a are configured by a wide band gap semiconductor. However, either one may be configured by a wide band gap semiconductor.

  Further, the semiconductor switching element 26a is attached to the heat radiating member 31 via the insulating sheet 35 so as to be electrically insulated from the fire spread prevention member 20, but the rectifier circuit 22 is attached to the heat radiating member 31 via the insulating sheet. May be. Thereby, a required insulation distance between internal wiring and other live parts can be further reduced, and the configuration of the rice cooker body 1 can be facilitated.

  Since the heating coil 8 and the cord reel 10 are cooled after the surface of the fire spread prevention member 20 is cooled, the temperature rise of the circuit elements other than the rectifier circuit 22 and the semiconductor switching element 26a made of wide band gap semiconductors. Can be reduced.

  In the second embodiment, it has been described that the rectifier circuit 22 and the semiconductor switching element 26a are attached to the heat radiating member 31, but the surface of the rectifier circuit 22 and the semiconductor switching element 26a on the side opposite to the power supply substrate 21 is the fire spread prevention member. You may make it attach to the inner surface of 20 closely. In that case, if the insulating sheet 35 is interposed between the fire spread prevention member 20 and electrically insulated, the semiconductor switching element 26a is interposed via liquid silicon (thermal diffusion compound) having better thermal conductivity than the insulating sheet 35. Therefore, the temperature increase of the semiconductor switching element 26a can be more efficiently suppressed.

  DESCRIPTION OF SYMBOLS 1 Rice cooker main body, 2 Inner pot, 3 Hinge part, 4 Outer lid, 5 Inner lid, 6 Side frame, 7 Bottom frame, 8 Heating coil, 9 Temperature sensor, 10 Code reel, 11 Bottom plate of rice cooker body, 13th 1 intake port (intake port), 14 second intake port, 15 exhaust port, 16 cartridge, 20 fire spread prevention member, 20a unevenness, 20b opening, 21 power supply board, 22 rectifier circuit, 23 choke coil, 24 smoothing capacitor, 25 Resonant capacitor, 26 inverter circuit, 26a semiconductor switching element, 26b diode, 27 power supply circuit, 28 drive circuit, 30 substrate holder, 31 heat radiating member, 31a top of heat radiating member, 32 screws, 33 screws, 34 screws, 35 insulating sheet, 40 control board, 41 control unit, 42 input unit, 43 display unit, 50 cooling fan drive circuit, 1 cooling fan.

Claims (12)

A main body having an intake port and an exhaust port, in which a cooking container is detachably accommodated;
Induction heating means disposed in the body for heating a cooking container in which an object to be cooked is stored;
A rectifier circuit that rectifies AC power of a commercial power supply and an inverter circuit that converts the output of the rectifier circuit into AC power of a predetermined frequency by turning on / off at least one semiconductor switching element and supplies the AC power to the induction heating means are mounted. A power supply board;
A heat dissipating member attached to the power supply board, and a semiconductor switching element of the rectifier circuit and the inverter circuit attached to a surface facing the power supply board,
It is formed in a box shape having an opening on one surface, and the opening is covered with the heat radiating member from the inside and the fire spread prevention member in which the power supply substrate is stored ,
The cooling air natural convection between the exhaust port and the intake port by the difference between the temperature and the outside temperature of the body during cooking, the surface of the heat dissipation member exposed from the opening of the fire prevention member is cooled Rice cooker characterized by being made . A main body having an intake port and an exhaust port, in which a cooking container is detachably accommodated;
Induction heating means disposed in the body for heating a cooking container in which an object to be cooked is stored;
A rectifier circuit that rectifies AC power of a commercial power supply and an inverter circuit that converts the output of the rectifier circuit into AC power of a predetermined frequency by turning on / off at least one semiconductor switching element and supplies the AC power to the induction heating means are mounted. A power supply board;
A heat dissipating member attached to the power supply board, and a semiconductor switching element of the rectifier circuit and the inverter circuit attached to a surface facing the power supply board,
A fire spread preventing member that is formed in a box shape having an opening on one surface, the opening is closed with the heat radiating member from the inside, and the power supply substrate is stored ;
A cooling fan provided in the main body,
Cooker wherein the sucked by the driving of the cooling fan from the intake port to the cooling air exhausted from the exhaust port, the surface of the heat dissipation member exposed from the opening of the fire prevention member is characterized in that it is cooled . Before SL rectifier circuit and the semiconductor switching element, cooker according to claim 1 or 2, wherein the opposite surface of the power substrate is mounted in close contact with the inner surface of the fire prevention member . The rectifier circuit and the cooker according to any one of claims 1-3, characterized in that either the one or both configured in wide band gap semiconductor of the semiconductor switching element. The rice cooker according to claim 4, wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond. The intake port is composed of a first intake port provided in a portion of the bottom plate of the main body substantially facing the lower part of the fire spread prevention member, and a second intake port provided in a lower part of the front surface of the main body,
The said exhaust port is provided in the part located above the upper part of the said fire spread prevention member among the back surfaces of the said main body, The rice cooker of any one of Claims 1-5 characterized by the above-mentioned. . The intake port is provided in a portion of the bottom plate of the main body that substantially faces the lower portion of the fire spread prevention member,
The exhaust port is provided in a lower portion of the front surface of the main body,
The cooling fan is installed between the lower part of the fire spread prevention member and the intake port,
When the cooling fan is driven, outside air is sucked from the intake port as cooling air, and after cooling the surface of the fire spread prevention member, it is discharged from the exhaust port through the induction heating means side. The rice cooker of any one of Claims 2-5 characterized by the above-mentioned. The rectifying circuit and the semiconductor switching element, rice cooker according to any one of claims 1-7, characterized in that it is arranged on the lower side of the fire prevention member in the power supply substrate. The rectifying circuit and the semiconductor switching element, rice according to any one of claims 1 to 8, wherein the heat radiating member is characterized in that it is soldered to the power source substrate after being fixed to the power supply board vessel. The spread preventing member, rice cooker according to any one of claims 1-9, characterized in that the irregularities are constituted by a sheet metal provided on the surface. The spread preventing member, the rectifier circuit and the cooker according to any one of claims 1 to 10, characterized in that either are one or both electrically insulated from the semiconductor switching element. The rectifying circuit and the semiconductor switching element, rice cooker according to any one of claims 1 to 11, characterized in that it is arranged to be positioned in the induction heating means side with respect to the power supply board .

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