JP2790081B2 - Electromagnetic rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic rice cooker for heating an inner pot using a heating means such as a work coil by high-frequency electromagnetic induction, and more particularly, to the above-mentioned heating means in this kind of electromagnetic rice cooker. The present invention relates to a configuration of a temperature control system of an element (for example, a switching transistor or a rectifying diode) that generates heat for operation.

[0002]

2. Description of the Related Art In recent years, an electromagnetic rice cooker employing an electromagnetic induction heating means such as a work coil as a heating means for heating an inner pot has been developed. The electromagnetic rice cooker has an advantage of very high thermal efficiency because an eddy current flows through the inner pot by high-frequency electromagnetic induction by an electromagnetic induction heating means such as a work coil to generate heat in the inner pot itself.

A high-frequency current is applied to the electromagnetic induction heating means such as the work coil from a power supply circuit having a rectifying element via a switching element such as a switching transistor driven by an oscillation output of a high-frequency oscillation circuit. Since the switching element or the rectifying element of the power supply circuit generates considerable heat during operation, a cooling means for cooling the switching element or the rectifying element of the power supply circuit is provided.

In general, a cooling fan is used as the cooling means. In this case, the cooling fan is disposed in the bottom space of the container body so as to correspond to the switching element or the rectifying element. It is configured such that the corresponding switching element or rectifying element is forcibly cooled by the cooling air being pumped.

[0005]

However, in the case of such a conventional electromagnetic rice cooker, the cooling fan is operated for a long time from the start of rice cooking to the end of rice cooking. There is a problem that noise such as a cooling fan rotation noise and a wind noise is generated and becomes annoying (especially when a rice cooking reservation is made in the early morning). In addition, since the operation time of the cooling fan becomes longer, a large-sized cooling fan having a long service life (lifetime) is required, so that the cost is increased and a large storage space is required in the container body. There are drawbacks such as the increase in size and weight, the need for a large installation space, and the inconvenience of carrying.

[0006] In addition, an outside air intake port and an exhaust port for ventilation are required, so that water and foreign substances easily enter the inside of the container body, the inside is poorly seen, the end of the carpet and paper, Difficulties such as sucking nylon also occur.

The present invention has been made in view of such a problem, and by enabling the temperature of the element itself, which generates heat, to be arbitrarily controlled, it is possible to reduce the required operation time of the conventional cooling fan. It is an object of the present invention to provide an electromagnetic rice cooker with a high noise level, which can be made as short as possible or in which the cooling fan itself can be omitted.

[0008]

Means for Solving the Problems Each of the present inventions is provided with the following means for solving the problems in order to solve the above-mentioned conventional problems and effectively achieve the object.

That is, the electromagnetic rice cooker according to the first aspect of the present invention includes an inner pot, a heating coil for electromagnetically heating the inner pot, a high-frequency oscillation circuit for driving the heating coil, and a rectifier. A power supply circuit, temperature detecting means for detecting the temperature of the rectifying element, and oscillation output control means for controlling an oscillation output of the high-frequency oscillation circuit in accordance with the temperature detected by the temperature detecting means. ing.

[0010] In the electromagnetic rice cooker according to the second aspect of the present invention, the oscillation output control means controls the oscillation output of the high-frequency oscillation circuit corresponding to the temperature of the rectifying element by the oscillation output control means.
When the temperature of the rectifier becomes equal to or higher than a predetermined temperature, the oscillation output of the high-frequency oscillation circuit is reduced.

An electromagnetic rice cooker according to a third aspect of the present invention includes an inner pot, a heating coil for electromagnetically heating the inner pot,
A switching element for flowing a high-frequency current through the heating coil;
A high-frequency oscillation circuit for driving the switching element, a power supply circuit including a rectifying element, a temperature detecting means for detecting a temperature of the switching element or the rectifying element, and an oscillation output control means for controlling an oscillation output of the high-frequency oscillation circuit And a total number determining means for determining a total number, wherein the oscillation output control means includes a temperature of the switching element or the rectifying element detected by the temperature detecting means and a total number determined by the total number determining means. Is controlled to a predetermined oscillation output corresponding to.

Further, the electromagnetic rice cooker according to the invention of claim 4 of the present application comprises an inner pot, a heating coil for electromagnetically heating the inner pot,
A switching element for flowing a high-frequency current through the heating coil;
A high-frequency oscillation circuit for driving the switching element, a power supply circuit including a rectifying element, temperature detecting means for detecting the temperature of the switching element or the rectifying element, and the switching element or the rectifying element detected by the temperature detecting means An oscillation output control means for lowering the oscillation output of the high-frequency oscillation circuit when the temperature of the high-frequency oscillation circuit becomes equal to or higher than a predetermined temperature; and a total number judgment means for judging the total number, wherein the oscillation output control means comprises: The oscillation output is controlled so as to correspond to the total number smaller than the total number determined by the number determination means by a predetermined amount.

According to a fifth aspect of the present invention, there is provided an electromagnetic rice cooker according to the first, second, third or fourth aspect of the present invention, further comprising a radiator, wherein the radiator includes a rectifier. Thermally bonded.

The electromagnetic rice cooker according to claim 6 of the present invention is the electromagnetic rice cooker according to claim 3 or 4,
A radiator is provided, and a switching element is thermally coupled to the radiator.

The electromagnetic rice cooker according to the invention of claim 7 of the present application is the electromagnetic rice cooker according to claim 3 or 4, wherein
It has a radiator, and a rectifier element and a switching element are thermally coupled to the radiator.

Further, the electromagnetic rice cooker according to the invention of claim 8 of the present application has a radiator, and the radiator is thermally coupled to a temperature detecting means.

[0017]

Therefore, the configuration of the electromagnetic rice cooker according to each invention of the present application exerts the following operation corresponding to each of the above configurations.

That is, first, in the configuration of the electromagnetic rice cooker according to the first aspect of the present invention, as described above, the inner pot, the heating coil for electromagnetically heating the inner pot, and the high-frequency oscillation circuit for driving the heating coil A power supply circuit having a rectifying element, a temperature detecting means for detecting a temperature of the rectifying element, and an oscillation output control for controlling an oscillation output of the high-frequency oscillation circuit in accordance with the temperature detected by the temperature detecting means. The temperature of the rectifying element is always detected and monitored by the temperature detecting means.

Then, in response to the detected temperature, the oscillation output control means causes the oscillation output of the high-frequency oscillation circuit for driving the heating coil to oscillate when the temperature of the rectifying element is higher than a steady temperature. On the other hand, while the output is lowered, the oscillation output is controlled to an appropriate oscillation output corresponding to normal rice cooking in a steady temperature state, so that an abnormal rise in the heat generation temperature is not caused.

As a result, the heat generation temperature of the rectifying element does not rise abnormally, and safe and reliable operation performance is ensured.

According to a second aspect of the present invention, there is provided the electromagnetic rice cooker according to the first aspect of the present invention, wherein the oscillation output of the high frequency oscillation circuit corresponding to the temperature of the rectifying element is controlled by the oscillation output control means. The control is specifically performed with a predetermined set temperature as a reference, and when the temperature of the rectifier becomes equal to or higher than the predetermined set temperature, the oscillation output of the high-frequency oscillation circuit is configured to be lowered by a predetermined amount, When the predetermined set temperature is set to an appropriate temperature corresponding to, for example, a heating temperature characteristic during rice cooking, it is possible to more appropriately control the rectifier element temperature without deteriorating the proper rice cooking performance. .

Further, in the electromagnetic rice cooker according to the invention of claim 3 of the present application, an inner pot, a heating coil for electromagnetically heating the inner pot,
A switching element for flowing a high-frequency current through the heating coil;
A high-frequency oscillation circuit for driving the switching element, a power supply circuit including a rectifying element, a temperature detecting means for detecting a temperature of the switching element or the rectifying element, and an oscillation output control means for controlling an oscillation output of the high-frequency oscillation circuit And a total number determining means for determining a total number, wherein the oscillation output control means includes a temperature of the switching element or the rectifying element detected by the temperature detecting means and a total number determined by the total number determining means. Is controlled to a predetermined oscillation output corresponding to.

As described above, the oscillation output of the high-frequency oscillation circuit is converted into a predetermined output in accordance with the temperature of the switching element or the rectifying element detected by the temperature detecting means and the total number determined by the total number determining means. By controlling, it is possible to more precisely control the heat generation temperature of the switching element or the rectifying element while minimizing the deterioration of the proper rice cooking performance.

Further, in the electromagnetic rice cooker according to the invention of claim 4 of the present application, an inner pot, a heating coil for electromagnetically heating the inner pot,
A switching element for flowing a high-frequency current through the heating coil;
A high-frequency oscillation circuit for driving the switching element, a power supply circuit including a rectifying element, temperature detecting means for detecting the temperature of the switching element or the rectifying element, and the switching element or the rectifying element detected by the temperature detecting means An oscillation output control means for lowering the oscillation output of the high-frequency oscillation circuit when the temperature of the high-frequency oscillation circuit becomes equal to or higher than a predetermined temperature; and a total number judgment means for judging the total number. The oscillation output is controlled so as to correspond to the total number smaller than the total number determined by the number determination means by a predetermined amount.

As described above, when the temperature of the switching element or the rectifying element detected by the temperature detecting means becomes equal to or higher than a predetermined temperature, the oscillation output of the high-frequency oscillation circuit is further judged by the number judgment means. If the output is controlled to a predetermined value corresponding to a number less than the determined number based on the number, the deterioration of the original proper rice cooking performance can be minimized, and the accuracy can be further improved. In addition, the control of the heat generation temperature of the switching element or the rectifying element can be realized.

The electromagnetic rice cooker according to a fifth aspect of the present invention is the electromagnetic rice cooker according to the first, second, third or fourth aspect of the present invention, further comprising a radiator, wherein the radiator has a rectifier element. Thermally bonded.

As described above, when a radiator such as a heat sink is provided, and the rectifier is thermally coupled to the radiator with good heat conductivity, the heat radiation performance of the rectifier itself is improved. In addition, when the oscillation output of the high-frequency oscillation circuit is appropriately controlled so as not to cause an abnormal rise in the heat generation temperature of the rectifying element, as described above, the oscillation in consideration of the heat generation amount from the rectification element is also considered. The output can be controlled, higher-precision and safe control can be realized, and a cooling fan can be eliminated.

Further, even if a cooling fan is provided in order to obtain higher cooling performance, the capacity can be reduced.

In the electromagnetic rice cooker according to the invention of claim 6 of the present application, the electromagnetic rice cooker according to claim 3 or 4 is
A radiator is provided, and a switching element is thermally coupled to the radiator.

As described above, when a radiator such as a heat sink is provided, and the switching element is thermally coupled to the radiator with good heat conductivity, the heat radiation performance of the switching element itself is improved. In addition, when the oscillation output of the high-frequency oscillation circuit is appropriately controlled so as not to cause an abnormal rise in the heat generation temperature of the switching element, the oscillation in consideration of the heat generation amount from the switching element is also considered. The output can be controlled, higher-precision and safe control can be realized, and a cooling fan can be eliminated.

Further, even if a cooling fan is provided in order to obtain higher cooling performance, the capacity can be reduced.

[0032] In the electromagnetic rice cooker according to the invention of claim 7 of the present application, the electromagnetic rice cooker according to the invention of claim 3 or 4 is characterized in that:
It has a radiator, and a rectifier element and a switching element are thermally coupled to the radiator.

As described above, when a radiator such as a heat sink is provided, and the rectifier element and the switching element are thermally coupled to the radiator with good heat conductivity, the heat radiation performance of the rectifier element and the switching element is improved. And
At the same time, as described above, when the oscillation output of the high-frequency oscillation circuit is appropriately controlled so as not to cause an abnormal increase in the heating temperature of each element, the oscillation taking into account the heat generation amount from the rectifying element or the switching element is considered. The output can be controlled, higher-precision and safe control can be realized, and a cooling fan can be eliminated.

Further, even if a cooling fan is provided in order to obtain higher cooling performance, the capacity can be reduced.

Further, the electromagnetic rice cooker according to the invention of claim 8 of the present application has a radiator, and the radiator is thermally coupled to a temperature detecting means.

As described above, when a radiator such as a heat sink is provided and the temperature detecting means is thermally coupled to the radiator with good heat conductivity, the temperature of the rectifying element or the switching element can be easily detected by the temperature detecting means. Becomes

[0037]

As described above, according to the electromagnetic rice cooker of the present invention, the amount of heat generated by an element that generates heat when a heating coil such as a rectifying element is driven is controlled. Abnormal heat generation of the element itself is prevented, and the life of the element is extended, the operating time of the cooling fan is shortened, the cooling fan capacity is reduced (reduction in rotation speed, downsizing), and the combination with a radiator It becomes possible to omit the cooling fan by improving the heat radiation performance. Therefore, the silent performance when cooking rice is improved.

Further, the rice cooker itself can be manufactured small, lightweight and at low cost.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(Embodiment 1) First, FIGS. 1 and 2 are a longitudinal sectional view and a horizontal sectional view of an electromagnetic rice cooker according to Embodiment 1 of the present invention, and FIG. 3 is a radiator in the electromagnetic rice cooker. The cross-sectional view of FIG.
Is an electric circuit diagram of an output control unit of the electromagnetic rice cooker, FIG. 5 is a waveform diagram of a main part of the output control unit of FIG. 4 of the electromagnetic rice cooker, and FIG. 4 is a flowchart showing the control contents of the output control unit of FIG.

The electromagnetic rice cooker according to the present embodiment is used for, for example, cooking rice and keeping heat. As shown in FIG.
Space part 4 configured so that inner pan 3 can be set inside
And a lid 2 for opening and closing the upper opening of the container main body 1 in an openable and closable manner.

The container body 1 has a cylindrical outer case 5 having a bottom and made of a synthetic resin forming a bottom wall and an outer wall, an inner case 6 forming an inner peripheral surface, and upper ends of both cases 5 and 6. And a shoulder member 7 made of a synthetic resin for connecting the inner pot 3, and the inner pot 3 is set so as to be removable therefrom.

The inner case 6 has a tubular case 6a made of a thin metal plate, the upper end of which is engaged with the shoulder member 7 and which is provided with a heater 8 at the center in the vertical direction of the outer peripheral surface. Dish-shaped case 6b made of synthetic resin engaged with the lower end of case 6a
A center sensor 9 is provided at the center of the bottom surface of the dish-shaped case 6b to be in contact with the bottom surface of the inner pot 3.

The center sensor 9 functions as an inner pot temperature detecting means for detecting the temperature of the inner pot 3, and detects whether the thermistor 10 serving as a temperature detecting section and the inner pot 3 are set. Inner pot set detection sensor 1
1 is built-in.

The center sensor 9 of this embodiment is a sensor which is disposed in a circular storage portion 12 formed in the center of the dish-shaped case 6b and is vertically movable and has the thermistor 10 built therein. It is provided with a holder 13 and a spring 14 for urging the sensor holder 13 upward (that is, in a direction of contacting the bottom surface of the inner pot 3). In the case of the present embodiment, the upper surface of the sensor holder 13 is a circular flat surface, and a sensor cap 15 that is in contact with the bottom surface of the inner pot 3 is provided.

The inner pot set detection sensor 11
The reed switch 16 and the magnet (not shown) provided at opposing positions on the outer periphery of the sensor holder 13 and the reed switch when the sensor holder 13 is moved downward (in other words, when the inner pot is set). Closure plate 17 inserted between 16 and magnet
And is constituted by.

An annular work coil (heating coil) 18 is arranged on the lower surface of the dish-shaped case 6b so as to surround the center sensor 9 and to correspond from the bottom surface of the inner pan 3 to the lower curved portion. I have. The work coil 18
The device acts as means for generating an induction magnetic field to the inner pot in the high-frequency electromagnetic induction heating device. Reference numeral FC denotes a ferrite core that closes so that the magnetism of the work coil 18 does not affect the underlying devices. Reference numeral 19 denotes a coil table, which holds the work coil 18 and a ferrite core F
C at the upper right position (in the case of this embodiment, the space 4 of the container body 1)
A mounting boss 19a serving as a mounting portion of the radiator 20, which will be described in detail later, is integrally formed on the rear side peripheral portion 4a side of FIG.

The lid 2 is composed of an upper plate 21 made of a synthetic resin constituting an upper surface, a lower plate 22 made of a synthetic resin constituting an outer peripheral annular portion on the lower surface, and a heat radiating cover for covering an opening in the lower plate 22. The plate 23 forms a hollow structure.
The lid 2 is rotatably attached to one side of the shoulder member 7 via a hinge mechanism 24, and has an open end engaged with a predetermined position of the lid 2. A lock mechanism 25 for keeping the lid 2 closed is provided.
Reference numeral 26 denotes a steam discharge port, and 27 denotes a lid heater.

In the rear peripheral portion 4 a of the space 4 of the container body 1, a rectifier of a switching transistor (switching element) 28 for controlling the energization of the work coil 18 and a rectifier diode bridge circuit 29 are provided. A radiator 20 having a heat sink structure for radiating heat generated in the element is provided. Since the rear side peripheral portion 4a of the space portion 4 has a relatively large extra space, it is suitable for arranging the radiator 20. By effectively using this extra space, The outer diameter of the container body 1 does not need to be increased. Moreover, since the radiator 20 is covered by the outer case 5 of the container body 1, there is no need to provide a special case.

The front side peripheral portion 4 in the space portion 4
A microcomputer board 45 is provided on c in a state supported by the mounting member 46. Note that the side peripheral portions 3d in the space portion 4 are narrow because the size of the container body 1 needs to be kept small, and it is generally difficult to obtain a space for installing the radiator 20.

The radiator 20 has a shape along the inner surface of the side wall of the container body 1 (in other words, the inner surface of the outer case 5) and is made of a plate made of a good heat conductor (for example, aluminum or aluminum alloy material). The radiator main body 20a and the radiator main body 2
A plurality of radiating fins 20b, 20b,... Extending in the vertical direction integrally protruding from the inner and outer surfaces of the radiator 20a. It is attached by being fixed by 30 (see FIG. 2). The switching transistor 28 and the rectifier diode bridge circuit 29 are directly attached to the radiator main body 20a, for example, on the inner and outer surfaces thereof with bolts 31 with good heat conductivity (thermal coupling). A temperature sensor (temperature detecting means) 60 for directly detecting the temperature of the radiator 20 which rises in response in response to the temperature (that is, the temperature of each rectifying element of the switching transistor 28 and the rectifying diode bridge circuit 29) is directly attached. (Thermal bonding).

With this configuration, the switching transistor 2 is connected to the air flow F (see the arrow in FIG. 1) that naturally convects upward from below in the space 4 of the container body 1.
8. Rectifier diode bridge circuit 29 and radiator 2
0 is exposed, and these devices are efficiently and naturally cooled by the convection air F. At this time, since the radiating fins 20b of the radiator 20 extend vertically, the radiating fins 20b
The contact area between the convection air F and the convection air F is increased.

The space 4 of the container body 1 is
Since it is not a closed space, the switching transistor 28 and the rectifier diode bridge circuit 2
A convection airflow F sufficient to cool the radiator 9 and the radiator 20 is obtained. In the present embodiment, the air inlet 33 is provided particularly at the bottom wall of the container body 1 (in other words, at a proper position on the bottom surface of the outer case 5). On the other hand, an air outlet 34 is formed in a portion of the side wall of the container body 1 (in other words, a side surface of the outer case 5) facing the radiator 20, and a convection airflow F flowing to the radiator 20 is formed. In order to improve the cooling efficiency.

Further, on the surface of the radiator 20, a black film 32 made of a black paint or a black oxide film is formed as shown in an enlarged view in FIG. This black film 3
By the formation of 2, the amount of radiated heat radiation from the radiator 20 increases, and the cooling of the switching transistor 28 and the rectifying diode bridge 29 can be more effectively achieved.

Further, in this embodiment, a heat insulating material 35 is provided inside the radiator 20. The heat insulating material 35 includes a cylindrical case 6a provided with the heat retaining heater 8 and the inner pot 3 and the heat retaining heater 8 on the outer peripheral side thereof.
It is interposed between the heat shield plate 36 and the heat shield plate 36 that blocks radiant heat. Due to the presence of the heat insulating material 35, the influence of radiant heat from the inner pot 3 and the heat retaining heater 8 does not affect the switching transistor 28, the rectifying diode bridge circuit 29, and the radiator 20.

Next, the configuration and operation of the output control circuit in the electromagnetic rice cooker of this embodiment will be described with reference to FIGS.

The output control circuit in this electromagnetic rice cooker is as follows:
It has a commercial AC power supply 39, the rectifier diode bridge circuit 29, a choke coil 37, an inverter circuit (broken line) 38, a transistor drive circuit 40, and a rice cooking control unit 50. Rectified by the rectifying diode bridge circuit 29 to be converted into a DC current, and then supplied to the inverter circuit 38 via the choke coil 37 and the smoothing capacitor 43.

The inverter circuit 38 includes, in addition to the choke coil 37, the work coil 18, and the smoothing capacitor 43, a switching transistor 28 connected in series to the work coil 18, and a flywheel connected in parallel to the switching transistor 28 with the opposite polarity. Diode 41
And a resonance capacitor 42 connected in parallel to the work coil 18. The switching transistor 28 of the inverter circuit 38 is turned on and off by an oscillation output from a transistor driving circuit 40 whose oscillation frequency is controlled by the rice cooking control unit 50.
The FF is driven. The transistor drive circuit 40 is formed by, for example, a high-frequency oscillation circuit having an oscillation frequency of about 25 KHz.

Now, when an ON signal is given from the transistor drive circuit 40 to the base of the switching transistor 28, the switching transistor 28 is turned ON (see point a in FIG. 5), and a current flows through the work coil 18 (FIG. 5). reference between the S ₁ of 5). Next, the transistor driving circuit 4
From 0 to the base of the switching transistor 28
When the F signal is supplied, the switching transistor 28
Is turned off (see point b in FIG. 5). When the switching transistor 28 is turned off, the work coil 18
Stored electromagnetic energy is discharged, a current flows through the closed loop circuit between the work coil 18 and resonant capacitor 42, resonant capacitor 42 is charged (see the segment S ₂ in FIG. 5). Until the resonance capacitor 42 is charged, a current flows through the work coil 18 in the same direction as when the switching transistor 28 was ON.

When the charging of the resonance capacitor 42 (discharging of the work coil 18) is completed (see point c in FIG. 5), the electric charge charged in the resonance capacitor 42 is discharged, and a current in the opposite direction is supplied to the work coil 18. flows (see the segment S ₃ in FIG. 5). Then, even after the discharge of the resonance capacitor 42 (charging of the work coil 18) is completed (see point d in FIG. 5), the electromagnetic energy accumulated in the work coil 18 is discharged by the discharge current of the resonance capacitor 42, and this electromagnetic energy is discharged. energy by a current flows in the direction of the work coil 18 → smoothing capacitor 43 → the flywheel diode 41 (see the segment S ₄ in FIG. 5).

When the stored electromagnetic energy of the work coil 18 is completely discharged (see point e in FIG. 5), one cycle is completed.

Subsequently, the transistor driving circuit 40
Supplies an ON signal to the switching transistor 28 again, and the next cycle starts.

The transistor driving circuit 40 as the high-frequency oscillation circuit is so arranged that the above one cycle is repeated, for example, 25,000 times per second (in the case of 25 KHZ).
ON / OF in response to an output control signal from the microcomputer of the rice cooking control unit 50 as the output control means.
Outputs F signal. Thus, the work coil 18
A high-frequency current of about 25 KHZ is passed through the
The electromagnetic induction heating control of the inner pot 3 is executed by the high-frequency current flowing through the work coil 18.

Incidentally, the work coil 18 as described above is used.
Output control circuit generates considerable heat during its operation. In particular, since each of the rectifying elements of the switching transistor 28 and the rectifying diode bridge circuit 29 is operated with a relatively large current, a large amount of heat is generated. Therefore, in this embodiment, at least the switching transistor 28 and the rectifier diode bridge circuit 29 are directly attached to the radiator 20 having the heat sink structure as described above, so that cooling is performed as effectively as possible by ventilation by natural convection. I have.

As is clear from FIG. 4, at the same time, the switching transistor 2
A temperature sensor 60 composed of a thermistor having a negative temperature characteristic is provided in the radiator 20 having the diode 8 and the diode bridge circuit 29, and the temperature T of the radiator 20 detected by the temperature sensor 60 is set to a predetermined set temperature (upper limit). Temperature) T ₁
C. or more, the rice cooking control unit 50 controls the transistor drive circuit 40, which is the high-frequency oscillation circuit.
The oscillation frequency (oscillation output) of the switching transistor 28 and the diode bridge circuit 29 is reduced by a predetermined value to reduce the amount of control current per unit time flowing through the switching transistor 28 and the diode bridge circuit 29. It is configured to lower the heat generation temperature.

Next, referring to the flowchart of FIG.
The transistor drive circuit 4 by the rice cooking control unit 50
The content of the oscillation frequency reduction control of 0 will be described.

That is, as shown in FIG. 6, the same control is started by turning on the rice cooker switch.

[0068] Then, enter the water absorption process in the step S _1,
Is turned ON in step S ₂ is set heating output of the work coil 18 to full power A (W). This allows
Water absorption heating is performed.

Next, the process proceeds to step S _3, the value of the detected value T of the temperature sensor 60 indicating the heating temperature, such as the switching transistor 28 in the heated state is a predetermined set temperature (upper limit temperature) T ₁ ° C. It is determined whether or not this is the case.

As a result, the temperature sensor 6 determined to be NO
When the detected value T 0 is set temperatures T ₁ lower than ℃, the step proceeds to S _5, further the center pot temperature t is given if the number of judgment reference temperature t among detected by the thermistor 10 of the sensor 9 Judge whether the temperature is ₁ ℃ or more.

[0071] On the other hand, the process proceeds to step S ₄ when it is determined YES, and by the heating output of the work coil 18 to control the oscillation frequency to reduce the rank low B (W) than the full power A (W) proceeds to a temperature judgment operation in the step S _4.

[0072] Results of the determination in step S _4, when the NO temperature t of the inner pot 3 is not in the above case number determination reference temperature t ₁ ° C. or more, the full power returns to below the step S ₂ A (W) or B (W) one rank lower
In while continuing the water heating after the heating, when it is determined YES, and the process proceeds to step S _6, if the number (rice weight) starts to determine control.

By the way, also at the start of該合number determination control, first detects the radiator temperature T by the temperature sensor 60 in step S ₇ First, the detection temperature T becomes the set temperature T ₁ ° C. or more Is always determined.

If the determination result is NO and the rectifying elements of the switching transistor 28 and the diode bridge circuit 29 do not generate heat when the temperature is equal to or higher than the above-mentioned set temperature T ₁ ° C, the process directly proceeds to step S ₈ and proceeds to step S _8. Is determined, and it is determined whether or not the detected temperature t is equal to or higher than the total number determination reference temperature t ₂ ° C. On the other hand, when the determination result is YES, without performing the calculation of the case the number of data proceeds to step S _9, large quantities if the number of data (full amount)
Proceeding in a small amount of the intermediate medium quantity determination operation medium- step S ₁₂ to be described later is set to the data. The medium amount data is used to set the heating output of the work coil 18 without causing an abnormal rise in the temperature of each of the rectifiers of the switching transistor 28 and the diode bridge circuit 29, and the heating output that can be cooked in a full or small amount. Is selected as the value corresponding to the setting.

[0075] On the other hand, the result of the determination in step S _8, N
If the total number determination reference temperature t ₂ ° C, which has been determined to be O, has not reached the temperature equal to or higher than t ₂ ° C, the above step S
Repeating the operation of ₆ ~S _8. On the other hand, when the result of the determination is YES and the total number determination reference temperature t ₂ ° C is reached,
The total number is determined based on the counting time from t ₁ ° C to t ₂ ° C.

Then, steps S ₁₀ , S ₁₁ ,
At S ₁₂ and S ₁₄ , it is determined whether the result of the total number is large, medium, or small, and one rank corresponding to the large, medium, or small of the total number determined in order. The heating output C (W), D (W),
E (W) is set and the inner pot 3 is heated.
In該判another setting operation, if it is set to medium amount in step S ₄ as described above is judged set corresponding to a medium amount of course. Then, after that, step S ₁₅ ,
The detected temperature T of the temperature sensor 60 again in S _16, S ₁₇ determines whether or not a said set temperature T ₁ ° C. or more.

If the result of each of the determinations in steps S ₁₅ , S ₁₆ , and S ₁₇ is NO, the flow advances to step S ₁₉ to determine whether the temperature t of the inner pot 3 has reached the cooking completion temperature of 130 ° C. , Then, if YES, step S
Moves to ₁₉ "steaming process" in and the "steaming process" is completed, further the control is terminated via the "incubating process" in step S _20.

On the other hand, if the result of each of the determinations in steps S ₁₅ , S ₁₆ , and S ₁₇ is equal to or higher than the set temperature T ₁ ° C of YES, the values are set in the preceding steps S ₁₁ , S ₁₃ , and S ₁₄ , respectively. The heating outputs C (W), D (W), and E (W), which become smaller for each rank sequentially according to the large, medium, and small judgment totals, are converted into heating outputs corresponding to the actual judgment totals. C (W), D
(W), heating power D one rank smaller than E (W)
(W), E (W), and 0 (W) are reset (reduced correction) to values that have been ranked down, and rice cooking is executed (oscillation output reduction). As a result, the heat generation temperature T of the switching transistor 28 and the rectifying element of the diode bridge circuit 29 quickly falls to a safe temperature value lower than T ₁ ° C.

[0079] Particularly, in the case of a small amount setting step S ₁₄ in the configuration (E (W) when), in step S ₂₁ 0
(W) = heating output is reset to zero,
On which the work coil 18 to OFF, to generate a warning alarm indicating an abnormal state by a method such as further sounding the buzzer 62 at step S _22, and so as to stop the cooking control in step S ₂₃ . Therefore, a fail-safe function at the time of abnormal temperature rise is also guaranteed.

Therefore, the configuration of the electromagnetic rice cooker according to the present embodiment has the following operation corresponding to the configuration.

That is, in the configuration of the electromagnetic rice cooker of this embodiment, as described above, the inner pot 3, the work coil 18 for electromagnetically heating the inner pot 3, and the heat source for supplying a high-frequency current to the work coil 18. The temperature of the radiator 20 to which the switching transistor 28 and the diode bridge circuit 29 are directly attached in an electromagnetic rice cooker including the conductive switching transistor 28 and the diode bridge circuit 29 and the transistor drive circuit 40 for driving the switching transistor 28 A temperature sensor 60 for detecting
A rice cooker control unit 50 is provided as output control means for controlling the oscillation output of the transistor drive circuit 40 in accordance with the temperature of the radiator 20 detected by the temperature sensor 60. The heating temperature T of the rectifying element of the transistor 28 and the diode bridge circuit 29 is detected and monitored.

The oscillation output of the transistor drive circuit 40 for driving the switching transistor 28 corresponding to the detected heating temperature T is, for example, the switching transistor 28 and the diode bridge circuit 2.
Heat generation temperature of the rectifying device 9 is appropriately controlled to lower the oscillation output when higher than the predetermined set temperature T _1.

As a result, switching transistor 28
In addition, an abnormal rise in the heat generation temperature of each rectifying element of the diode bridge circuit 29 is eliminated, and the temperature is maintained at an appropriate steady state.

The predetermined set temperature T ₁ for performing the control is set to an appropriate temperature in accordance with, for example, the heating temperature characteristic during rice cooking, so that the rice cooking performance is not deteriorated (the deterioration is minimized). Control) to prevent an abnormal increase in the heat generation temperature.

Further, in the above configuration, the radiator 20 having a heat sink structure having high heat radiation performance is provided.
The switching transistor 28 and the diode bridge circuit 29 are directly attached thereto, and the temperature sensor 60 is thermally coupled to the switching transistor 28 and the diode bridge circuit 29 with good heat conductivity. And temperature detection becomes accurate and easy. In this configuration, as described above, the oscillation output of the transistor drive circuit 40 is appropriately controlled so as not to cause an abnormal rise in the heat generation temperature, so that the cooling fan can be eliminated.

As described above, in the electromagnetic rice cooker according to the present embodiment, the amount of heat generated by each of the rectifying elements of the switching transistor 28 and the diode bridge circuit 29 is controlled. As a result, the life of each element can be prolonged, and the cooling fan can be omitted. Therefore, the silent performance when cooking rice is improved.

Further, the rice cooker itself can be reduced in size and weight,
Cost reduction can be achieved.

In the structure of the present embodiment, the radiator 20
And a rectifying element of a diode bridge circuit 29 provided in a normal power supply circuit, in addition to the switching transistor 28, is provided by being thermally coupled to the single radiator 20 in common. In this way, the heat dissipation performance of the rectifying element itself is improved, and the switching transistor 2 corresponds to the heat generation temperature determined by the total heat generation amount including the heat generation amount from the rectification element.
However, as another configuration, for example, two sets of the radiators 20 described above are separately provided, and the switching transistor 28 and the diode bridge circuit 29 are individually attached to each of the radiators 20. The two sets of temperature sensors 60 and 60 individually detect the heat generation temperature, and the same control as described above is performed when the heat generation temperature on one side becomes equal to or higher than a predetermined set temperature T ₁ ° C. You can also.

With such a configuration, the heat generation amounts of the respective elements which differ from each other and have different allowable upper limit temperatures are individually affected without being affected by the heat generation amount of the partner element. High responsiveness enables more precise control.

Further, in this case, the heat radiation capacity of the radiator 20 itself can be reduced, and the size can be reduced. Therefore, installation using a narrower surplus space becomes possible, and constraints on the space factor are relaxed.

The location of the radiator 20 in the above embodiment is not limited to the above-mentioned case, but may be provided at any location where natural cooling is possible.

Further, if the heat radiator 20 is provided to improve the heat radiation performance as in the above-described embodiment, the cooling fan can be omitted as described above. May be added. Also in that case, if the above configuration is adopted, the size of the cooling fan can be reduced as much as possible.

When such a cooling fan is provided, the element temperature is sufficiently lowered by turning on the fan, so that, for example, step S in the flowchart of FIG.
Instead of the work coil output 0 (W) set at ₂₁ put the fan ON process, subsequent alarm in step S _22, S _23, also (omitted) without performing the processing of rice discontinued, raising cook it It is also possible to use a control sequence.

On the other hand, the cooling fan may be turned on only when the element temperature does not decrease despite the lowered oscillation output as described above.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electromagnetic rice cooker according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG. 1;

FIG. 3 is an enlarged sectional view of a radiator portion in the electromagnetic rice cooker according to the embodiment of the present invention.

FIG. 4 is an electric circuit diagram showing a configuration of an output control circuit in the electromagnetic rice cooker according to the embodiment of the present invention.

FIG. 5 is a waveform chart showing a work coil control operation of the output control circuit of FIG. 4;

FIG. 6 is a flowchart showing output control contents by a rice cooking control unit of the output control circuit of FIG. 4;

[Explanation of symbols]

1 is a container body, 3 is an inner pan, 4 is a space portion, 4a is a rear side peripheral portion, 4b is a rear corner portion, 5 is an outer case, 6 is an inner case, 6a is a cylindrical case, and 6b is a dish-shaped case. , 8 is a heater, 9 is a center sensor, 10 is a thermistor, 18 is a work coil, 19 is a ferrite core, 19a is a mounting boss, 20 is a radiator, 20a is a radiator main body, 20b is a radiator fin, and 28 is a switching transistor. , 29 is a diode bridge circuit, 33 is an air inlet, 34 is an air outlet, 40 is a transistor drive circuit, 50 is a rice cooking control unit, and 60 is a temperature sensor.

Claims (8)

(57) [Claims] 1. An inner pot, a heating coil for electromagnetically heating the inner pot, a high-frequency oscillation circuit for driving the heating coil,
An electromagnetic rice cooker comprising a power supply circuit having a rectifying element, a temperature detecting means for detecting a temperature of the rectifying element, and an oscillation output of the high-frequency oscillating circuit corresponding to the temperature detected by the temperature detecting means. An electromagnetic rice cooker provided with oscillation output control means for controlling the temperature. 2. The oscillation output control means controls the oscillation output of the high-frequency oscillation circuit corresponding to the temperature of the rectifier element when the temperature of the rectifier element exceeds a predetermined temperature. The electromagnetic rice cooker according to claim 1, wherein the rice cooker is configured to perform the operation. 3. A power supply comprising an inner pot, a heating coil for electromagnetically heating the inner pot, a switching element for supplying a high-frequency current to the heating coil, a high-frequency oscillation circuit for driving the switching element, and a rectifying element. A circuit, a temperature detecting means for detecting a temperature of the switching element or the rectifying element, an oscillation output control means for controlling an oscillation output of the high-frequency oscillation circuit, and a total number judging means for judging a total number. The output control means is controlled to a predetermined oscillation output corresponding to the temperature of the switching element or the rectifying element detected by the temperature detection means and the combined number determined by the combined number determination means. An electromagnetic rice cooker, characterized in that: 4. A power supply including an inner pot, a heating coil for electromagnetically heating the inner pot, a switching element for supplying a high-frequency current to the heating coil, a high-frequency oscillation circuit for driving the switching element, and a rectifying element. A circuit, temperature detecting means for detecting the temperature of the switching element or the rectifying element, and when the temperature of the switching element or the rectifying element detected by the temperature detecting means becomes equal to or higher than a predetermined temperature, Oscillation output control means for lowering the oscillation output, and a total number determination means for determining the total number are provided, and the oscillation output control means reduces the total number to a total number smaller than the total number determined by the total number determination means. An electromagnetic rice cooker characterized by being controlled to a corresponding oscillation output. 5. A radiator, wherein a rectifying element is thermally coupled to the radiator.
Or the electromagnetic rice cooker according to 4. 6. A radiator, wherein a switching element is thermally coupled to the radiator.
Or the electromagnetic rice cooker according to 4. 7. The electromagnetic rice cooker according to claim 3, further comprising a radiator, wherein the rectifier and the switching element are thermally coupled to the radiator. 8. A radiator, wherein a temperature detecting means is thermally coupled to the radiator.
Electromagnetic rice cooker according to 2, 3, 4, 5, 6 or 7.