JP2003059633A - Induction cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction cooker in which the user can recognize that the support board is hot even after the power supply switch is switched off and the stand-by power can be made zero and, which is reliable. SOLUTION: The induction cooker comprises a power supply switch 2, an inverter circuit 4 that outputs high frequency from the service power supply 1, a heater coil 5, a temperature sensor 8 that detects the temperature of the support board 6, a display means 13 that makes warning when the temperature of the support board 6 is higher than the predetermined temperature, a cooling means 12 for cooling the support board 6, a control means 9 that controls the inverter circuit 4 and drives the display means 13 and the cooling means 12 when the support board 6 is hot, an auxiliary contact 3 that detects the open and close of the power supply switch 2, and a relay 14 connected in parallel with the power supply switch 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable induction heating cooker capable of displaying a warning even when the power switch is turned off and displaying a warning when the support after heating is hot.

[0002]

2. Description of the Related Art FIG. 7 is a circuit diagram of a conventional induction heating cooker. In the figure, 1 is a commercial power supply, 2 is a power switch, and 1
Reference numeral 0 is a control power supply circuit that is connected to the power supply switch 2 and generates control power from the commercial power supply 1. Reference numeral 4 is an inverter circuit that is connected to the power supply switch 2 and outputs a high frequency from the power supply supplied from the commercial power supply 1. The heating coil 4 is connected to the heating coil 4, and the pan 7 supported by the supporting plate 6 arranged above the heating coil 5 is heated. Reference numeral 8 is a temperature sensor for detecting the temperature of the support plate, 9 is a control power source supplied from the control power source circuit 10, and the inverter circuit 4
Is a control means for controlling.

A commercial power source 1 is supplied by a relay 11 which is turned on by a fan drive signal output from a control means 9 when the temperature of the support plate 6 is higher than a predetermined temperature by a temperature sensor 8. It is a cooling fan that is operated by being operated, and includes a support plate 6 and an apparatus body case (not shown).
Cool inside. 13 is a temperature sensor 8 when the temperature of the support plate 6 is higher than a predetermined temperature,
An LED or the like is used as a display light for displaying a warning such as "high temperature caution" by a display light drive drive signal output from the control means 9. When there are a plurality of heating coils, a corresponding indicator light is provided.

FIG. 8 shows a detailed circuit diagram of the control means 9,
Reference numeral 9a is a high temperature determination unit that determines whether the temperature detected by the temperature sensor 8 is equal to or higher than a predetermined temperature, and outputs a fan drive signal and an indicator light drive signal when the temperature is higher than this temperature. Tr1 is a base whose resistance is R1. Through the high temperature determination unit 9a
And the collector is connected to the exciting coil 11a of the relay 11.
Transistor with a grounded emitter, Tr2
Is a transistor whose base is connected to the high temperature determination unit 9a via the resistor R2, whose collector is connected to the indicator lamp 13 and whose emitter is grounded.

The operation of the conventional induction heating cooker configured as described above will be described below. First, when the power switch 2 is turned on, the commercial power source 1 is input to the control power circuit 10 and the inverter 4. The control power supply circuit 10 generates a control power supply and supplies it to the inverter circuit 4 and the control means 9. When a drive signal is input from the control means 9 to the inverter circuit 4,
Direct current obtained by rectifying the commercial power supply 1 is converted into high frequency, and high frequency magnetic flux is generated in the heating coil 5 to heat the container 7.

On the other hand, the high temperature judging section 9a of the control circuit 9 judges whether the temperature of the support plate 6 detected by the temperature sensor 8 is a predetermined temperature, for example, 70 ° C. or higher. The fan drive signal and the indicator light drive signal are output. With this fan drive signal, the transistor Tr1 is turned on, a current flows in the exciting coil of the relay 11, the relay contact 11b is turned on, and the cooling fan 1 is turned on.
2 drives. Similarly, the transistor Tr2 is turned on by the indicator light drive signal, and a warning of high temperature caution is displayed on the indicator light 13.

[0007]

However, in the above-described conventional induction heating cooker, when the support base 6 after heating is high in temperature, the indicator lamp 13 is used to inform the user that the control means 9 is high in temperature. However, when the power switch 2 is turned off, the input of the control power source of the control means 9 is cut off, so that the high temperature determination unit 9a detects that the temperature of the support plate 6 detected by the temperature sensor 8 is high. Since it is not possible to determine whether the temperature is higher than the predetermined temperature and neither the fan drive signal nor the indicator light drive signal is output, the cooling fan 1
2 is not driven, and the indicator lamp 13 is not displayed either, and the user cannot recognize that the support plate 6 is hot.

If the power switch 2 is left turned on after heating, the cooling fan 12 is driven and the warning light is displayed on the indicator lamp 13 when the temperature is high, but an unnecessary load is applied to the inverter, the heating coil and the like. There was a problem that current flows.

Further, the electric power consumption of the induction heating cooker is large (for example, 1.5 KW for 100 V and 4.8 for 200 V).
Therefore, if there is a contact of the power switch 2 or a load relay for a load, the contact has a short life unless the capacity is large.

The present invention has been made in order to solve the above problems. Even after the power switch is turned off, the cooling fan is driven and the warning light is displayed on the indicator lamp so that the user can support the support plate. It is possible to recognize that the temperature is high, and useless load current does not flow when the power supply is not needed, standby power can be set to 0, and the capacity of the power switch and load relay can be reduced and the contact An object is to provide a highly reliable induction heating cooker having a long life.

[0011]

An induction heating cooker according to the present invention includes a power switch for opening and closing a commercial power source, an inverter circuit for outputting a high frequency from the commercial power source, and a heating coil connected to the inverter circuit. A temperature sensor for detecting the temperature of the support plate supporting the cooking container, a display unit for displaying a warning when the temperature of the support plate is a high temperature equal to or higher than a predetermined temperature, and a cooling unit for cooling the support plate. In an induction heating cooker that controls the inverter circuit and that controls the display means and the cooling means when the support plate is at the high temperature, an opening / closing detection means for detecting opening / closing of the power switch And a power circuit opening / closing means that is connected in parallel with the power switch to open / close the commercial power source, and the control means includes:
When the open / close detection means detects that the power switch is off, the supply of the commercial power to the inverter circuit is stopped, and when the support base is at a high temperature, the power circuit open / close means is closed to continue the operation, The display means and the cooling means are kept driven.

Further, the opening / closing detecting means of the power switch is an auxiliary contact interlocking with the power switch section.

When there are a plurality of heating coils, the display means provides a display corresponding to the temperature of each heating coil in the vicinity of each heating coil.

A load opening / closing means is provided between the commercial power source and the inverter circuit, and the control means opens / closes the opening / closing means only when the inverter circuit is stopped.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a circuit diagram of an induction heating cooker showing a first embodiment of the present invention, FIG. 2 is a circuit diagram of a main part of FIG. 1, and FIG. 3 is a timing chart for explaining the operation. In FIG. 1, 1 is a commercial power supply, 2 is a power switch, and 3 is an auxiliary contact which is an opening / closing detection means for detecting opening / closing of the power switch 2, and is turned on / off in conjunction with the power switch 2. Reference numeral 21 is a power switch means composed of the power switch 2 and the auxiliary contact 3. Reference numeral 14 is a relay which is connected in parallel with the power switch 2 and is a power circuit opening / closing means for opening / closing a commercial power supply.

Reference numeral 10 is a control power supply circuit which is connected to the power supply switch 2 to generate control power from the commercial power supply 1 and 4 is an inverter circuit which is connected to the power supply switch and is an inverter which outputs a high frequency from the power supply supplied from the commercial power supply 1. 5,
Is a heating coil connected to the inverter circuit 4, and heats a pan 7 which is a cooking container supported by a support plate 6 arranged above the heating coil 5. Reference numeral 8 is a temperature sensor that detects the temperature of the support plate, and 9 is a control unit that operates by the control power supply supplied from the control power supply circuit 10 and controls the inverter circuit 4.

Reference numeral 12 denotes the relay 1 when the inverter circuit 4 is operating, or when the temperature of the support plate 6 by the temperature sensor 8 is higher than a predetermined temperature.
A cooling fan 1 operates to cool the support plate 6 and the inside of the apparatus main body case (not shown). The temperature sensor 8 indicates a temperature of the support plate 6 by the temperature sensor 8 when the temperature is higher than a predetermined temperature. The LED is used as a display lamp which is a display means for displaying a warning such as "."

FIG. 2 shows a detailed circuit diagram of the control means 9,
9a is a high temperature determination unit that determines whether the temperature detected by the temperature sensor 8 is higher than a predetermined temperature (for example, 70 ° C. or higher), and outputs a fan drive signal and a high temperature caution signal when the temperature is higher than this temperature. The base of Tr1 is resistance R
1 is connected to the high temperature determination unit 9a, the collector is connected to the exciting coil 11a of the relay 11, and the emitter is grounded. Tr2 has the base connected to the high temperature determination unit 9a via the resistor R2 and the collector is displayed. It is a transistor connected to the lamp 13 and having its emitter grounded. D1
And D2 are diodes connected in series between the output terminals of the fan drive signal and the indicator light drive signal of the high temperature determination unit 9a, and Tr.
Reference numeral 3 is a transistor whose base is connected via a resistor R2 and whose collector is connected to the exciting coil 14a of the relay 14. Reference numeral 9b is a power SW open / close determination unit that determines whether or not the power switch 2 is opened / closed by the auxiliary contact 3 and outputs a stop signal to the inverter circuit 4 when the power switch 2 is off. The high temperature determination unit 9a outputs the indicator light drive signal and displays the temperature on the indicator lamp 13 even if the temperature is not high.

The operation of the induction heating cooker according to the first embodiment of the present invention configured as described above will be described below with reference to FIGS. First, when the power switch 2 is turned on (see FIG.
(B)), the commercial power supply 1 is input to the control power supply circuit 10 and the inverter 4 (FIGS. 3C and 3D). Control power supply circuit 1
0 generates a control power supply, and the inverter circuit 4 and the control means 9
(Figs. 3 (e) and (f)). When a (driving, or control) signal is input from the control means 9 to the inverter circuit 4, the direct current obtained by rectifying the commercial power supply 1 is converted into a high frequency and a high frequency is output to generate a high frequency magnetic flux in the heating coil 5 (Fig. 3 (g)) The container 7 is heated. It should be noted that although not shown, setting such as cooking conditions and automatic on / off are performed by an operation panel connected to the control means 9, and the power switch 2 is a main switch manually performed.

On the other hand, the high temperature determination unit 9a of the control circuit 9 determines whether the temperature of the support plate 6 detected by the temperature sensor 8 is a predetermined temperature, for example, 70 ° C. or higher as shown in FIG. 3 (a). It is determined that the fan drive signal and the high temperature caution signal are output at the same time when the operation of the inverter circuit 4 is started.
With this fan drive signal, the transistor Tr1 is turned on, a current flows in the exciting coil of the relay 11, the relay contact 11b is turned on, and the cooling fan 12 is driven (FIG. 3 (h)). When heating is started, the transistor Tr2 is turned on by the indicator light drive signal, but a warning of high temperature is displayed on the indicator light 13 by the high temperature caution signal ((FIG. 3 (i)). By the high temperature caution signal, the transistor Tr3 is turned on, a current flows through the exciting coil 14a of the relay 14, and the relay contact 14b is turned on (FIG. 3 (k)).

Next, when the power switch 2 is turned off at t3 as shown in FIG. 3B after the heating is completed, the auxiliary switch 3 is turned off in conjunction with the power switch 2 (FIG. 3).
By (j)), the control means 9 detects that the power switch 1 is off, outputs a commercial power supply stop signal to the inverter circuit 4, and stops the inverter circuit 4. At this time,
When the temperature of the support base 6 is 70 ° C. or higher by the temperature sensor 8, the fan drive signal and the high temperature caution signal are continuously output from the high temperature determination unit 9a, so that the transistor Tr3 is turned on and the exciting coil 14a of the relay 14 is turned on. A current flows and the relay contact 14b continues to be in the ON state (see FIG.
(K)), the state in which the control power is supplied to the control means 9 continues (FIG. 3 (f)). Similarly, the transistor Tr1
Is turned on, current flows through the exciting coil of relay 11,
The relay contact 11b is turned on and the cooling fan 12 is driven (FIG. 3 (h)). Similarly, Tr2 is on, and the indicator lamp 13 keeps displaying the warning of high temperature caution (FIGS. 3 (h) and 3 (i)).

Then, as shown in FIG. 3A, 7 is set at t4.
When the temperature is lower than 0 ° C., the fan drive signal and the high temperature caution signal are not output from the high temperature determination unit 9a, so the transistor Tr3 is turned off and the relay 14 is turned off (see FIG. 3).
(K)), the supply of control power to the control means 9 is stopped (FIG. 3 (f)). Similarly, the transistors Tr1 and Tr2
Is turned off, the cooling fan 12 is stopped, and the warning display of the indicator lamp 13 disappears (FIGS. 3 (h) and 3 (i)).

As described above, even after the power switch 2 is turned off, the cooling fan is driven and the warning light is displayed on the indicator lamp so that the user can recognize that the support plate is at a high temperature. When no power supply is needed, useless load current does not flow, and standby power can be set to zero. Furthermore, the auxiliary switch 3 that is interlocked with the power switch 2 causes the power switch 2
Is turned off, the commercial power supply stop signal is output to the inverter circuit 4 to stop the inverter circuit 4, so that the capacity of the power switch 2 can be reduced and the life of the contacts of the power switch 2 can be extended.

Embodiment 2. Although the case where the number of the heating coils is one is shown in the first embodiment, the number of the heating coils is plural in the present embodiment. Second Embodiment FIG. 4 is a circuit diagram of an induction heating cooker showing a second embodiment of the present invention. In the figure, the same parts as those in FIG. 4a and 4b are inverter circuits, 5a and 5b are heating coils, 6a and 6b are support plates, 7a and 7b are pots, and 8a and 8
b is a temperature sensor.

In this structure, the operation is the same as that of the first embodiment, but there are a plurality of temperature sensors 8a and 8b for detecting the temperatures of the supporting plates 6a and 6b corresponding to the heating coils 5a and 5b, respectively. A warning display corresponding to the sensors 8a and 8b is displayed, and when the output of at least one of the temperature sensors 8a and 8b is equal to or higher than a predetermined temperature, the cooling fan 12 is driven to correspond to the temperature sensors 8a and 8b. A warning of high temperature is displayed on the display lamps 13a and 13b. Then, when the power switch 2 is turned off, the inverter circuit 4 is stopped, and when the output of at least one of the temperature sensors 8a and 8b is equal to or higher than a predetermined temperature, the cooling fan 12 continues to be driven and the display is performed. Light 1
The warning of high temperature continues to be displayed on 3a and 13b. When all the outputs of the temperature sensors 8a and 8b are lower than the predetermined temperature, the cooling fan 12 is stopped and the indicator light is turned off.

As described above, the plural indicator lights 13a, 13b
With the temperature sensors 8a and 8b corresponding to the plurality of heating coils 5a and 5b, a warning display corresponding to each temperature of the support plates 6a and 6b can be displayed, and which heating coil is hot can be clarified.

Embodiment 3. 5 is a circuit diagram of an induction heating cooker showing a third embodiment of the present invention, and FIG. 6 is a timing chart for explaining the operation. In the figure, the same parts as those of FIG. Reference numeral 15 is a load relay which is an opening / closing means provided between the commercial power source and the inverter circuit.

The operation of this configuration will be described with reference to FIGS. First, when the power switch 2 is turned on at time t1 (FIG. 6A), the commercial power supply 1 is input to the control power supply circuit 10. The control power supply circuit 10 generates the control power supply, and the inverter circuit 4 and the control means 9 are supplied. From the control means 9,
A heating output start signal is input to the load relay 15 at t2 (see FIG. 6).
(B)), the load relay 15 is turned on (Fig. 6).
(C)). Then, the inverter is driven at t3 (see FIG.
(D)), the direct current rectified from the commercial power supply 1 is converted into a high frequency and a high frequency is output, and a high frequency magnetic flux is generated in the heating coil 5 to heat the container 7.

Next, when the heating output stop signal is input from the control means 9 to the inverter circuit 4 at t4 (FIG. 6 (b)), the inverter stops at t4 (FIG. 6 (d)) and the load is applied at t5. The relay 15 is turned off (FIG. 6 (c)). The other operations are the same as those in the first embodiment, and the description thereof will be omitted.

As described above, the switching means is provided between the commercial power source and the inverter circuit 4, and the control means 9 turns the load relay 15 on and off only when the inverter circuit 4 is stopped. The life of the contacts of the relay 15 can be extended.

[0031]

As described above, according to the present invention, the power switch for opening and closing the commercial power source, the inverter circuit for outputting a high frequency from the commercial power source, and the heating coil connected to the inverter circuit are supported. A temperature sensor for detecting the temperature of the support plate, a display unit for displaying a warning when the temperature of the support plate is higher than a predetermined temperature, a cooling unit for cooling the support plate, and the inverter circuit. In an induction heating cooker having a control means for controlling and controlling the display means and the cooling means when the support plate is at the high temperature, an open / close detecting means for detecting open / close of the power switch, and the power switch And a power circuit opening / closing means connected in parallel with the commercial power source for opening / closing the commercial power supply, wherein the control means has the opening / closing detection means for turning off the power switch. When it is detected, the supply of the commercial power to the inverter circuit is stopped, and when the support base is at a high temperature, the power circuit opening / closing means is closed and the operation is continued to drive the display means and the cooling means. Since it is left as it is, even after turning off the power switch, the cooling fan is driven and the warning light is displayed on the indicator light, so that the user can recognize that the support plate is high temperature. The capacity can be reduced and the life of the contacts of the power switch can be extended.

Further, since the opening / closing detecting means of the power switch is an auxiliary contact interlocking with the power switch section, the opening / closing of the power switch can be detected with a simple structure.

Further, when there are a plurality of heating coils, the display means displays the indications corresponding to the temperatures of the respective heating coils in the vicinity of the respective heating coils, so that the high temperature portion can be made clear and a warning can be displayed. .

Further, the load switching means is provided between the commercial power source and the inverter circuit, and the control means opens and closes the switching means only when the inverter circuit is stopped, so that the capacity of the load relay is reduced. At the same time, the life of the contact can be extended.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an induction heating cooker showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a main part of the induction heating cooker according to the first embodiment of the present invention.

FIG. 3 is a timing chart explaining the operation of the induction heating cooker according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram of an induction heating cooker showing a second embodiment of the present invention.

FIG. 5 is a circuit diagram of an induction heating cooker showing a third embodiment of the present invention.

FIG. 6 is a timing chart explaining the operation of the induction heating cooker according to the third embodiment of the present invention.

FIG. 7 is a circuit diagram of a conventional induction heating cooker.

FIG. 8 is a circuit diagram of a main part of a conventional induction heating cooker.

[Explanation of symbols]

1 commercial power supply, 2 power switch, 3 auxiliary contacts, 4
Inverter circuit, 5 heating coils, 6 support plates, 7 pots,
8 temperature sensor, 9 control means, 9a high temperature judgment part, 9
b Power SW open / close detection determination unit, 10 control power circuit, 1
1, 14, 15 relays, 12 cooling fans, 13 indicator lights.

Claims (4)

[Claims] 1. A power switch that opens and closes a commercial power source, an inverter circuit that outputs a high frequency from the commercial power source, a heating coil that is connected to the inverter circuit, and a temperature sensor that detects the temperature of a support plate that supports a cooking container. A display unit for displaying a warning when the temperature of the support plate is higher than a predetermined temperature, a cooling unit for cooling the support plate, and controlling the inverter circuit,
In an induction heating cooker comprising a control means for driving the display means and the cooling means when the support plate is at the high temperature, an open / close detection means for detecting the open / close state of the power switch, and the parallel connection with the power switch And a power supply circuit opening / closing means for opening / closing the commercial power supply, wherein the control means stops the supply of the commercial power supply to the inverter circuit when the opening / closing detection means detects that the power switch is off, An induction heating cooker characterized in that, when the temperature of the support base is high, the power circuit opening / closing means is closed to continue the operation, and the display means and the cooling means are kept driven. 2. The induction heating cooker according to claim 1, wherein the opening / closing detecting means of the power switch is an auxiliary contact interlocking with the power switch section. 3. The heating means according to claim 1, wherein when there are a plurality of heating coils, the display means displays a display corresponding to the temperature of each heating coil in the vicinity of each heating coil. Induction heating cooker. 4. The load opening / closing means is provided between the commercial power source and the inverter circuit, and the control means opens / closes the opening / closing means only when the inverter circuit is stopped. The induction heating cooker according to any one of 3 above.