JPH0346787A - Induction heating cooker - Google Patents

Abstract

PURPOSE:To use a low heat-proof unit without guaranteeing the heat-proof property of parts composing a cooker up to an abnormal cooling condition, by stopping the oscillation of an inverter circuit and operating an abnormal alarm device by a control circuit, when the rotation frequency of a fan motor becomes out of a specific scope. CONSTITUTION:When a power source switch 11 is turned on, a fan motor 23 is rotated. In this case, the light receiving element 26 of a fan rotation frequency detecting device 24 repeats the light-receiving and the non-light-receiving periodically, because the light from a radiation element 25 is blocked by the fan 23. The detecting device 24 converts the light-receiving and the non-light-receiving of the light receiving element 26 into signals, and outputs them to a control circuit 21. The circuit 21 counts the repeating number of the light-receiving and the non-light-receiving signals, and when the number is out of a specific scope, it detects that the cooling condition is abnormal, prohibits the driving of the switching element 19, stops the oscillation of an inverter circuit 16, and outputs a signal to an alarm device 22 to operate the alarm device 22.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an induction heating cooker, and more particularly to a cooling state detection means.

2. Description of the Related Art As shown in FIG. 3, in a conventional induction heating cooker of this type, a cooling fan motor 1 is connected to a commercial power source 2, and when a power switch 3 is turned on, the fan motor 1 always rotates. , the inverter circuit 4, and other components are cooled. Furthermore, among the components constituting the inverter circuit 4, the switching element 6 has high self-heating due to switching loss and is susceptible to thermal stress. 6 supplies the temperature detection signal of the switching element 6 to a control circuit that controls the inverter circuit 4 . When the control circuit 7 determines that the temperature of the switching element 5 has exceeded a certain temperature based on the temperature detection signal from the temperature detection means 6, it prohibits the driving of the switching element 5, stops the oscillation of the inverter circuit 4, and removes the parts. was protected from heat stress.

Further, a disconnection detection means 8 is provided for detecting a disconnection of the fan motor 1, and when the fan motor 1 does not rotate due to the disconnection, the disconnection detection means 8 supplies a stop signal to the control circuit 7, and the inverter circuit 4 oscillation was prohibited and the components were protected from heat stress.

Problems to be Solved by the Invention In such a conventional configuration, the temperature detection means 6 detects the temperature of the switching element 6 and stops the oscillation of the inverter circuit 4 in the circuit components and mechanical components other than the switching element 5. Until now, it was necessary to determine the heat resistance grade and cooling conditions of each component so that it would stay within the guaranteed temperature.

Hey! ! , if the intake port through which the fan motor 1 sucks cooling air is blocked by a carpet or raised part of the carpet, resulting in a sealed state, or if a foreign object such as a toothpick or chopstick is inserted into the intake port and the fan becomes locked. Even in this case, the inno(-) circuit 4 will continue to oscillate until the switching element 6 reaches a certain temperature change or higher, and if the pot 9 is heated under the above conditions, the switching loss of the switching element 6 will be reduced. , the product is heated normally for about 10 to 20 minutes.The pot 9 is sufficiently warmed within that heating time, and the ambient temperature inside the product rises due to self-heating and radiant heat from the pot 9, while the circuit components are not sufficiently cooled. death,
The temperature of the parts themselves also rises.

The temperature rise at this time is higher than the normal cooling state, so there was a problem in that it was necessary to use components with high heat resistance, assuming the air intake port was sealed and the fan was locked.

The present invention solves these problems, and allows the use of low heat resistant parts without having to guarantee the heat resistance of the parts that make up the induction heating cooker even in abnormal cooling states such as the air intake port sealed state and fan lock state. It is intended to do so.

Means for Solving the Problems and Technical Means of the present invention for solving the above problems are: an inverter circuit connected to a commercial power source; a control circuit for controlling the inverter circuit; and a fan for cooling the inverter circuit, etc. a fan rotation speed detection means for detecting the rotation speed of the fan motor and outputting a signal to the control circuit; and an abnormality notification means controlled by the control circuit, and the control circuit detects the rotation speed of the fan motor and outputs a signal to the control circuit. When the rotational speed falls outside a predetermined range, the oscillation of the inverter circuit is stopped and the abnormality notification means is activated.

Function The induction heating cooker of the present invention has the above-mentioned configuration, so that foreign objects such as toothpicks or chopsticks may be inserted into the cooling air intake port, or metal chips may enter the shaft of the fan motor, causing the fan to malfunction. When the fan is in a locked state or when the fan does not rotate due to a disconnection of the motor, the control circuit can of course detect the locked state of the fan based on the detection signal from the fan rotation speed detection means and can stop the oscillation of the inverter circuit. In addition, if the cooling air intake port is sealed by a carpet or raised carpet, etc., the intake resistance applied to the fan motor will increase, and the fan rotation speed will be lower than normal. Based on the detection signal from the number detection means, it is possible to detect whether the intake air of the cooling air is closed or not, and the oscillation of the inverter circuit can be stopped. The control circuit stops the oscillation of the inverter circuit in the abnormal cooling state as described above, and operates the abnormality notification means, so that the user can be notified that the cooling state is abnormal. be.

As a result, it is no longer necessary to guarantee the heat resistance of the parts that make up the induction heating cooker in abnormal cooling conditions such as when the cooling fan motor is locked or when the cooling air intake port is sealed. All that is needed is a heat-resistant design.

Furthermore, if there is an abnormality in the cooling state, the user can recognize it at the start of cooking, so the user can always use the product in the normal cooling state and cook continuously.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

In FIG. 1, a commercial power source 1o includes a power switch 11.
A rectifier 12 is connected to the output terminal of the rectifier 12 via an input capacitor 13 and a tochitsuk coil 14.
and a series circuit of filter capacitor 16 are connected. An inverter circuit 16 is connected in parallel to the filter capacitor 15. Inverter circuit 1
Reference numeral 6 comprises a parallel circuit of a heating coil 17 and a commutating capacitor 18, and a flywheel diode 2o connected antiparallel to a switching element 19.

A control circuit 21 controls the on/off state of the switching element 19 and also controls the operation of the abnormality notification means 22. In addition, the cooling fan motor 23 is rectified by 'a1'.
The fan rotation speed detecting means 24 detects the rotation speed of the cooling fan motor 23 and supplies a detection signal to the control circuit 21. Second
The figure shows an embodiment of the fan rotation speed detecting means 24, in which a light emitting element 25 and a light receiving element 26 of a photosensor are installed with a cooling fan 23 in between.

In the above configuration, when the power switch 11 is turned on, the control circuit 21 drives the switching element 19 and causes the inverter circuit 16 to oscillate. When the inverter circuit 16 oscillates, a high frequency current is supplied to the heating coil 17 and the pot 27 is heated.

Also, when the power switch 11 is turned on, the fan motor 23
rotates. At this time, the light receiving element 26 of the fan rotation speed detecting means 24 periodically repeats receiving and not receiving light because the light from the light emitting element 26 is blocked by the fan 23.

The fan rotation speed detection means 23 converts light reception or non-reception of the light receiving element 26 into a signal, and outputs the signal to the control circuit 21 . Control circuit 2
1 counts the number of times the light reception/non-light reception signal is repeated from the fan rotation speed detection means 24, and if the number of times is outside a predetermined range, it is detected that the cooling state is abnormal, and the driving of the switching element 19 is prohibited; The oscillation of the inverter circuit 16 is stopped, a signal is output to the abnormality notification means 22, and the abnormality notification means 22 is operated.

As described above, according to the induction heating cooker of the embodiment of the present invention,
When the fan motor 23 is in a locked state or the cooling air intake port is sealed, the rotation speed of the fan motor 230 is different from that in the normal cooling state, so by detecting the rotation speed with the fan rotation speed detection means 24, The control circuit 21 can stop the oscillation of the inverter circuit 16 and notify of an abnormality in the cooling state.

As a result, it is only necessary to design the heat resistance of each component of the induction heating cooking IT in a cooling state in which the fan motor 23 rotates normally and the intake port is normal, and it is necessary to ensure component heat resistance in abnormal cooling states. will disappear.

In addition, the user can recognize from the operation of the abnormality notification means 22 that the oscillation of the inverter circuit 16 has stopped due to an abnormal cooling state, so the product can always be used in a normal cooling state. It is.

In addition to the effects of the invention, as is clear from the description of the embodiments, according to the present invention, the locked state of the cooling fan motor and the sealed state B'fc of the intake port are detected, and the oscillation of the inverter circuit is stopped.
In addition, since an abnormal state of cooling is notified, parts with low heat resistance can be used for the parts whose temperature is guaranteed in the abnormal cooling state.

Moreover, since the user can recognize that the cooling state is abnormal at the start of cooking, the inverter circuit is always cooled in a normal cooling state and cooking can be continued.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an induction heating cooker showing an embodiment of the present invention, Fig. 2 is a configuration diagram of the fan rotation speed detection means, and Fig. 3 is a circuit diagram of an induction heating cooker showing a conventional example. be. 1o... Commercial power supply, 16... Inverter circuit, 21... Control circuit, 22...
Abnormality notification means, 23...Fan motor, 24.
...Fan rotation speed detection means.

Claims (1)

[Claims] An inverter circuit connected to a commercial power source, a control circuit that controls the inverter circuit, a fan motor that cools the inverter circuit, etc., and a fan that detects the rotation speed of the fan motor and outputs a signal to the control circuit. and an abnormality notification means controlled by the control circuit, and the control circuit stops the oscillation of the inverter circuit when the rotation speed of the fan motor falls outside a predetermined range, and the abnormality notification means controls the abnormality notification means. An induction heating cooker made to work.