JP2765501B2 - 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 configured to be able to heat an inner pot by high-frequency electromagnetic induction by a work coil, and more particularly to a control for generating heat for controlling energization in such an electromagnetic rice cooker. The present invention relates to a cooling structure of an element (for example, a power transistor and a rectifying diode bridge).

[0002]

2. Description of the Related Art In recent years, an electromagnetic rice cooker employing an electromagnetic induction heating device as a heating means for heating an inner pot has been developed. In the case of the electromagnetic rice cooker, Joule heat generated by eddy current generated in the inner pot by high-frequency electromagnetic induction by a work coil is intended to be used for heating the inner pot.

Incidentally, the high-frequency electromagnetic induction by the work coil requires control elements (for example, a power transistor and a rectifying diode bridge) for controlling energization of the work coil, and these control elements operate. Since heat is sometimes generated, a means for cooling them is indispensable.

A conventionally known cooling means is a cooling fan. In this case, the control element and the cooling fan are arranged in a bottom space of the container body, and the control element is cooled by cooling air sent from the cooling fan. It is to be cooled.

[0005]

However, in the case of a conventionally known electromagnetic rice cooker, the cooling fan is operated from the start of rice cooking to the end of rice cooking. There is a drawback that a wind noise is generated and rice cooking cannot be performed quietly (especially when the rice cooking is reserved early in the morning). Further, since the operation time of the cooling fan becomes longer, a large-sized cooling fan having a long service life is required, so that the cost is increased, and a large storage space is required and the weight is increased.

The present invention has been made in view of the above points, and generates heat for controlling energization of a work coil by shortening an operation time of a cooling unit for cooling an element during rice cooking as much as possible. It is an object of the present invention to reduce operating noise while efficiently cooling a control element.

[0007]

According to the basic structure of the present invention, as a means for solving the above-mentioned problems, a container body configured to accommodate an inner pan heated by high-frequency electromagnetic induction by a work coil is provided. An electromagnetic rice cooker comprising: an inner pot temperature detecting means for detecting the temperature of the inner pot; a control element for controlling energization of the work coil; and a cooling means for cooling the control element. Element temperature detection means for detecting the temperature of the control element, operation start control means for starting the operation of the cooling means when the element temperature detected by the element temperature detection means reaches a set temperature, and the inner pot temperature Operation stop control means for stopping the operation of the cooling means when the temperature of the inner pot detected by the detection means reaches a predetermined temperature.

In the basic configuration of the present invention, a second operation stop control means for stopping the operation of the cooling means when the element temperature detected by the element temperature detecting means has decreased by a predetermined temperature due to the start of the operation of the cooling means. Is preferable in that the cooling means can be operated in response to the temperature decrease of the control element due to the operation of the cooling means.

In addition, a plurality of types of step-by-step setting of the operation start set temperature of the cooling means by the operation start control means are set, and a plurality of step-by-step temperature increase corresponding to the operation start set temperature are set as the cooling means. It is preferable to employ the one having the cooling capacity in that the capacity of the cooling means can be adjusted according to the temperature rise of the control element (in other words, the operation with a large operation noise can be reduced as much as possible).

In addition, the control element is mounted on a heat radiating plate made of a good heat conductor, and the heat radiating plate is disposed in a side peripheral portion in a space of the container body and has a large number of heat radiating fins extending in a vertical direction. This is preferable in that the temperature rise of the control element that generates heat can be suppressed (in other words, the operation time of the cooling unit can be reduced). In this case, if a black film is formed on the surface of the heat sink, heat is radiated. The amount of radiation and heat radiation from the plate can be increased, which is more preferable.

It is preferable to dispose a heat shield plate on the inner side of the heat radiator plate in order to prevent the influence of heat from the inner pan on the heat radiator plate. It is preferable to provide a heat insulating material in the point that heat influence from the inner pan to the heat sink can be more effectively prevented.

[0012]

According to the basic structure of the present invention, the following effects can be obtained by the above means.

That is, the control element (for example, a power transistor, a rectifying diode bridge, etc.) generates heat and rises in temperature by controlling the energization of the work coil, but when the temperature detected by the element temperature detecting means becomes higher than the set temperature. The operation of the cooling means is started from and the operation of the cooling means is stopped when the inner pot temperature detected by the inner pot temperature detecting means reaches a predetermined temperature. Therefore, the operation time of the cooling means is from the time when the element temperature rises to the set temperature to the time when the inner pot temperature reaches the predetermined temperature.

In the basic configuration of the present invention, a second operation stop control means for stopping the operation of the cooling means when the temperature detected by the element temperature detecting means has decreased by a predetermined temperature due to the start of the operation of the cooling means. When the control unit is provided, the control element is cooled by the operation of the cooling means, and when the temperature of the control element decreases by a predetermined temperature, the operation of the cooling means is stopped, so that noise can be reduced.

In addition, a plurality of types of step-by-step setting of the operation start set temperature of the cooling means by the operation start control means are set, and a plurality of step-by-step temperature increase corresponding to the operation start set temperature are set as the cooling means. When a device having a cooling capacity of is adopted, the capacity of the cooling means can be adjusted in response to a rise in the temperature of the control element (in other words, operation with a large operating noise can be reduced as much as possible). The noise can be further reduced.

Further, the control element is attached to a heat radiating plate made of a good heat conductor, and the heat radiating plate is arranged at a side peripheral portion in a space of the container body and has a large number of heat radiating fins extending in a vertical direction. In this case, even when the cooling means is not operating, the control element and the heat radiating plate are exposed to the airflow flowing from the lower part to the upper part in the space of the container main body, and the temperature rise of the control element that generates heat can be suppressed ( In other words, the operation time of the cooling means can be shortened). At this time, since the radiation fins extend in the vertical direction, the contact area between the radiation fins and the air flow is increased, and the effect of suppressing the temperature rise of the control element is obtained.

Further, when a black film is formed on the surface of the heat radiating plate, the amount of radiation radiated from the heat radiating plate increases, and heat transfer from the control element that generates heat to the heat radiating plate is promoted.

Further, when a heat shield plate is provided on the inner side of the heat radiating plate, the heat influence from the inner pan and the heat retaining heater to the heat radiating plate is prevented, and the cooling effect of the control element and the heat radiating plate is prevented. In this case, if a heat insulating material is provided on the inner side of the radiator plate, the heat influence on the radiator plate from the inner pan and the heat retaining heater can be more effectively prevented.

[0019]

According to the present invention, there is provided an inner pot temperature detecting means for detecting the temperature of the inner pot, comprising a container main body configured to accommodate an inner pot heated by high-frequency electromagnetic induction by a work coil. An electromagnetic rice cooker comprising: a control element for controlling energization of the work coil; and cooling means for cooling the control element, wherein an element temperature detecting means for detecting a temperature of the control element; Operation start control means for starting the operation of the cooling means when the temperature detected by the temperature detection means reaches a set temperature, and when the inner pot temperature detected by the inner pot temperature detection means reaches a predetermined temperature. Operation stop control means for stopping the operation of the cooling means is provided, and the cooling means is operated from a time when the control element generates heat and rises to a set temperature to a time when the inner pot temperature reaches a predetermined temperature. Having to, it will be able to reduce the operation time of the cooling means while suppressing the temperature rise of the control element, the reduction of operating noise in the cooking there is excellent effect that can be achieved.

Further, since the operation time of the cooling means is short, it is not necessary to employ an expensive cooling means having a long service life, and a small and inexpensive cooling means can sufficiently achieve the object. That is, there is an effect that the cost can be reduced and the space occupied by the cooling means can be reduced.

[0021]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

First Embodiment FIGS. 1 and 2 show a longitudinal sectional view of an electromagnetic rice cooker according to a first embodiment of the present invention and connection diagrams of electric elements in the electromagnetic rice cooker.

The electromagnetic rice cooker of this embodiment is designed to serve both for cooking rice and for keeping warm. As shown in FIG. 1, the electromagnetic rice cooker has a space 4 in which the inner pot 3 can be set. It has a container main body 1 having a double structure 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 main 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. The inner pot 3 is set so as to be removable therefrom.

The inner case 6 has a cylindrical case 6a made of a thin metal plate having an upper end engaged with the shoulder member 7 and having a heater 8 at the upper and lower central portions of the outer peripheral surface. 6a, a dish-shaped case 6b made of synthetic resin engaging with the lower end of the dish 6a. At the center of the bottom of the dish-shaped case 6b, there is provided a center sensor 9 which is in contact with the bottom of the inner pan 3. ing.

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 at 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 pan 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 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 pot 3 to the lower curved portion. The work coil 18 functions as a magnet generating means in the high-frequency electromagnetic induction heating device. Reference numeral 19 denotes a ferrite core that holds the work coil 18 at a predetermined position and shields the magnet so that the magnetic force of the work coil 18 does not affect the underlying devices.

In this embodiment, a radiator plate 20 is provided below the ferrite core 19, and the radiator plate 20 is provided with a control element for controlling the energization of the work coil 18. A certain power transistor 21 and a rectifying diode bridge 22 and an element temperature sensor 23 acting as element temperature detecting means for detecting the temperatures of these control elements are mounted. Since the control element generates heat during operation, a cooling fan 24 as cooling means for cooling the power transistor 21 and the rectifying diode bridge 22 is provided below the heat sink 20. The cooling fan 24 is composed of a fan motor 25 supported in a suspended state with respect to the heat sink 20 and an axial-flow type impeller 26 pivotally supported on a rotation shaft 25a of the fan motor 25. I have. Reference numeral 27 denotes an air inlet formed at the bottom of the outer case 5, and reference numeral 28 denotes an air outlet formed at the front side peripheral portion of the outer case 5.

The lid 2 includes an upper plate 29 made of synthetic resin forming the upper surface, a lower plate 30 made of synthetic resin forming the outer peripheral annular portion on the lower surface, and a heat radiating cover for opening the opening in the lower plate 30. The disk 31 has a hollow structure.
The lid 2 is rotatably attached to one side of the shoulder member 7 via a hinge mechanism 32, and has an open end engaged with a predetermined position of the lid 2. A lock mechanism 33 for maintaining the lid 2 closed is provided.
Reference numeral 34 denotes a steam discharge port, 35 denotes a lid heater, 36 denotes a mounting member provided on the front side peripheral portion 4a of the space 4, and 37 denotes a microcomputer board supported by the mounting member 36.

An annular heat insulating material 38 is disposed outside the cylindrical case 6a of the inner case 6, and an annular heat shield plate 39 is disposed outside the heat insulating material 38.

Next, an example of a power supply circuit and a control circuit in the electromagnetic rice cooker of this embodiment will be described with reference to FIG.

The power supply circuit in this electromagnetic rice cooker is as follows:
The rectifying diode bridge 22 includes a filter coil 40 and an inverter circuit 41. After the AC current supplied from the commercial AC power supply 42 is rectified by the rectifying diode bridge 22 and converted into a DC current. Through a filter coil 40 for absorbing surge current and the like.

The inverter circuit 41 includes a power transistor 21 connected in series to the work coil 18, a control circuit 43 for controlling a switching operation of the power transistor 21, and a flywheel diode connected in parallel to the power transistor 21. 44, a resonance capacitor 45 connected in parallel with the work coil 18, and a filter capacitor 46.

The operation of the inverter circuit 41 is as follows. O from the control circuit 43 to the power transistor 21
When the N signal is given, the power transistor 21 is turned on
Then, a current flows in the direction of the filter capacitor 46 → the work coil 18 → the power transistor 21. Next, an OFF signal is supplied from the control circuit 43 to the power transistor 21, and the power transistor 21 is turned off. When the power transistor 21 is turned off, the work coil 18
The electromagnetic energy stored in the work coil is discharged, and the work coil 1
A current flows through a closed loop circuit including the capacitor 8 and the resonance capacitor 45, and the resonance capacitor 45 is charged. Until the resonance capacitor 45 is charged, a current flows through the work coil 18 in the same direction as when the power transistor 21 was ON.

When the charging of the resonance capacitor 45 is completed, the charge charged in the resonance capacitor 45 is discharged, and a current flows in the work coil 18 in the opposite direction. And, even if the discharge of the resonance capacitor 45 is completed,
The electromagnetic energy accumulated in the work coil 18 is discharged by the discharge current 5 and a current flows in the direction of the work coil 18 → the filter capacitor 46 → the flywheel diode 44 by the electromagnetic energy. When the stored electromagnetic energy of the work coil 18 has been discharged, one cycle ends. Then, the control circuit 43 supplies an ON signal to the power transistor 21 again.

The control circuit 43 outputs an ON / OFF signal so that the above one cycle is repeated, for example, 30,000 times per second. As a result, high-frequency electromagnetic induction heating by the work coil 18 is performed.

The power supply circuit for the work coil 18 generates heat during its operation. In particular, since the power transistor 21 and the rectifying diode bridge 22 are operated with a relatively large current, their heat generation is large. Therefore, in this embodiment, at least the power transistor 21
The rectifying diode bridge 22 is attached to the heat radiating plate 20 as described above, and the cooling is performed by the forced air flow from the cooling fan 24. As in this embodiment, not only the power transistor 21 and the rectifying diode bridge 22 are attached to the radiator plate 20, but also control elements that generate heat, such as the flywheel diode 44, the resonance capacitor 46, and the filter capacitor 46, are radiator plates. 20.

The power supply circuit includes temperature information from the element temperature sensor 23 (that is, the power transistor 21 as a control element or the rectifier diode bridge 2).
2 and the cooling fan 24 (specifically,
A cooling fan control circuit 47 for controlling start / stop of the fan motor 25) is additionally provided.

As shown in FIG. 3, the cooling fan control circuit 47 starts the cooling fan 24 from when the element temperature T ₁ detected by the element temperature sensor 23 reaches a set temperature Ts (for example, 125 ° C.). The operation start control means 48 for starting the operation of the cooling fan and the cooling fan at the point in time when the element temperature T ₁ detected by the element temperature sensor 23 decreases by a predetermined temperature ΔT (for example, 10 ° C.) by the start of the operation of the cooling fan 24. Operation stop control means 49 for stopping the operation of 24
It is comprised including.

Next, with reference to a flowchart shown in FIG. 4 and a time chart shown in FIG. 5, an operation control of the cooling fan 24 in the electromagnetic rice cooker according to the present embodiment at the time of cooking rice will be described. In FIG. 5, a dotted line T ₁ indicates a detected temperature curve of the element temperature sensor 23, and a solid line T ₂
Indicates a detection temperature curve of the center sensor 9 (in other words, a rice cooking curve).

[0043] is a standby mode in step S ₁ (i.e., cooking start is enabled mode), step S
When the ON operation of the cooking switch (not shown) is confirmed in _2, heated by work coil 18 is started in step S _3, enters the water absorption step, steps are performed up cooking in step S _4. Then, step S ₅
In, the detected temperature T ₁ detected by the element temperature sensor 23 is compared with a set temperature Ts (for example, 125 ° C.). The detected temperature T ₁ is the temperature of a control element (for example, the power transistor 21 and the rectifying diode bridge 22) that generates heat by controlling the energization of the work coil 18 during rice cooking, and rises with the progress of rice cooking (FIG. 5).

[0044] and, T ₁ ≧ Ts in step S ₅
(= 125 ° C.) and becomes, operation of the cooling fan 24 is started in step S _6. The operation start is executed by operation start control means 48 in the control circuit 47.

By starting the operation of the cooling fan 24, the radiator plate 20 and the control elements (for example, the power transistor 21 and the rectifier diode bridge 22) are cooled and the temperature is lowered. because performs determined whether the cooking is completed at step S _7, in the case of affirmative determination, the process proceeds to step S ₈ stops operation of the cooling fan 24, then the process proceeds to step S _9, incubating process Move to. On the other hand, if a negative determination is made in step S _7, the step S ₁₀
In T ₁ ≦ Ts-ΔT of whether it (= 10 ° C.) and the determination is made, if it is determined that T ₁ ≦ Ts-ΔT is the operation of the cooling fan 24 is stopped in step S _11, and then returns to the step S _4. The operation stop is executed by operation stop control means 49 in the control circuit 47. In the case where a negative determination is made in step S _10, and then returns to step S _6. Here, ΔT is the hysteresis of the element temperature sensor 23, which prevents the cooling fan 24 from repeating starting and stopping. In the case where a negative determination is made in step S _2, the ON operation of the insulation / cancel switch (not shown) is confirmed in step S _12, in the case of affirmative determination, moves to incubating process proceeds to step S ₉ and, the process returns to step S ₁ when a negative determination is made.

That is, the operation of the cooling fan 24 is performed while the temperature T ₁ detected by the element temperature sensor 23 is Ts ≦ T ₁ ≦ Ts−ΔT (that is, the time indicated by B ₁ and B ₂ in FIG. 5). The control element that generates heat (for example, the power transistor 21 and the rectifying diode bridge 2)
2) The breakage due to the temperature rise and the like are prevented, and the required minimum operation of the cooling fan 24 is sufficient as compared with the conventional example (that is, the cooling fan 24 is continuously operated during the rice cooking). The operation time of the cooling fan 24 can be reduced while suppressing the temperature rise of the control element. Accordingly, it is possible to achieve a reduction in the operating noise during the cooking of rice,
It is not necessary to employ an expensive one having a long service life, and a small and inexpensive cooling fan 24 can sufficiently achieve its purpose. Therefore, cost reduction can be achieved, the space occupied by the cooling fan 24 can be reduced, and power consumption can be reduced. Reduction can also be achieved.

In this embodiment, the element temperature sensor 2
3 detected temperatures T ₁ by the, but there is a possible to perform only the operation of the cooling fan 24 period has become _{Ts ≦ T 1 ≦ Ts-ΔT} , detected from the time when the detected temperature T ₁ is exceeded the set temperature Ts it may continue the operation of the cooling fan 24 until the cooking completion regardless decreasing temperature T _1.

Second Embodiment FIGS. 6 and 7 show the contents of a power supply circuit and a control circuit for a cooling fan in an electromagnetic rice cooker according to a second embodiment of the present invention.

In this embodiment, the cooling fan control circuit 4
As shown in FIG. 6, temperatures T ₁ and T ₂ detected by the element temperature sensor 23 and the center sensor 9 are input to 7, which are different from the first embodiment in that
In addition to the operation stop control means 49, the center sensor 9
The inner pot temperature T ₂ is only in a predetermined temperature (for example, the temperature is increased cooked) operation stop control means 50 for stopping the operation of the cooling fan 24 when it reaches T ₀ is attached to be detected (Fig. 7).

[0050] Therefore, as shown in the flow chart of FIG. 8, step if to compare between the detection temperature T ₂ and the temperature T ₀ up cooking of the center sensor 9 at step S _7, was the T ₂ ≧ T ₀ operation of the cooling fan 24 in S ₈ is stopped, then step steaming in step S ₉ and step S _10, the process proceeds to incubating process. On the other hand, T ₂ <
While a T ₀ (i.e., before the end up cooked) is compared with the detected temperature T ₁ of the set temperature Ts-[Delta] T of the element temperature sensor 23 is made the routine proceeds to step _{S 11, T 1 ≦ Ts-} Δ
If it is determined as T, the cooling in step S ₁₂ fan 2
Operation of the 4 is stopped, and then returns to step S _4. In the case where a negative determination is made in step S _2, the ON operation of the insulation / cancel switch (not shown) is confirmed in step S _13, in the case of affirmative determination, moves to incubating process proceeds to step S ₁₀ and, the process returns to step S ₁ when a negative determination is made. That is, in the case of the present embodiment, the operation of the cooling fan 24 is performed only for the time indicated by reference numerals B ₁ and B ₂ ′ in FIG. 5, and the operation time can be further reduced. Other functions and effects are the same as those in the first embodiment.

Third Embodiment FIG. 9 shows the contents of a control circuit for a cooling fan in an electromagnetic rice cooker according to a third embodiment of the present invention.

In the case of this embodiment, the cooling fan control circuit 4
7 includes an element temperature sensor 23 and a center sensor 9.
Has become the temperature T _1, T ₂ is input sensed by, the point where the differences with embodiment 1, the operation stop control means 4
In place of 9, operation stop control means 50 for stopping the operation of the cooling fan 24 when the inner pot temperature T ₂ detected by the center sensor 9 reaches a predetermined temperature (for example, the cooking temperature) T ₀ is additionally provided. The only thing that has been done.

Next, the operation control of the cooling fan 24 in the electromagnetic rice cooker according to the present embodiment will be described with reference to the flowchart shown in FIG. 10 and the time chart shown in FIG.

[0054] is a standby mode in step S ₁ (i.e., cooking start is enabled mode), step S
When the ON operation of the cooking switch (not shown) is confirmed in _2, heated by work coil 18 is started in step S _3, enters the water absorption step, steps are performed up cooking in step S _4. Then, step S ₅
Whether or not it is a cooling memory (in other words,
It is determined whether or not the cooling fan 24 has been operated in the past), but the control element temperature T ₁ has not risen to the set temperature Ts for starting the operation of the cooling fan 24 during the cooking process. so will be negative, sets the detection temperatures T ₁ detected by the element temperature sensor 23 proceeds to step S ₆ temperature Ts (for example, 1
25 ° C.). The detected temperature T ₁ is the temperature of a control element (for example, the power transistor 21 and the rectifying diode bridge 22) that generates heat by controlling the energization of the work coil 18 during rice cooking, and rises with the progress of rice cooking (FIG. 11).

[0055] Then, in a case where it is determined that T ₁ <Ts in step S _6, T ₂ ≧ T in step S _{7
When the} temperature is determined to be ₀ (that is, before the temperature of the control element rises to the set temperature Ts, the detection temperature T _{2 of the} center sensor 9)
When the temperature reaches the cooking temperature T ₀ ), the cooling fan 2
4 without starting driving, the process proceeds to step steaming in step S _8, and then proceeds to incubating process in step S _9.

Meanwhile, when it is determined that T ₁ ≧ Ts in step S _6, set the cooled memory in step S _10, the operation of the cooling fan 24 is started in step S _11. The start of the operation is executed by the operation start control means 48 in the control circuit 47 for the cooling fan.

When the cooling fan 24 starts to operate, the radiator plate 20 and the control elements (for example, the power transistor 21 and the rectifier diode bridge 22) are cooled to lower the temperature. However, the temperature T ₂ detected by the center sensor 9 decreases. until it reaches a temperature T ₀ up cook the operation of the cooling fan 24 is continued. That is, if it is determined that T ₂ <T ₀ in step S _12, it returns to step S _4, an affirmative determination is made in that case the step S ₅ (i.e., cooling the memory is determined to be set)
Therefore, than is the operation of the cooling fan 24 is continued proceeds to step S _11.

[0058] If it is determined that T ₂ ≧ T ₀ in step S ₁₂ (i.e., the raised cooking is finished), and resets the cooled memory in step S _13, step S ₁₄
Stop operation of the cooling fan 24 in, then proceeds to step S _8. The operation stop is performed by the control circuit 4 for the cooling fan.
7 is executed by the operation stop control means 50.

[0059] Incidentally, when negative determination is made in step S _2, the ON operation of the insulation / cancel switch (not shown) is confirmed in step S _15, when the affirmative determination is kept proceeds to step S ₉ proceeds to step returns to step S ₁ when a negative determination is made.

That is, when the temperature T ₁ detected by the element temperature sensor 23 becomes T ₁ ≧ Ts, the center sensor 9
Until the detected temperature T ₂ becomes T ₂ ≧ T ₀ (ie,
The cooling fan 24 is operated only for the time indicated by C in FIG. 11 to prevent the control elements (for example, the power transistor 21 and the rectifying diode bridge 22) from being damaged due to an increase in temperature, and to prevent the control element (for example, the power transistor 21 and the rectifying diode bridge 22) from being damaged. , The cooling fan 24 was operated continuously during the cooking of rice.)
It is only necessary to operate the cooling fan 24 with a minimum required in comparison with the cooling fan 2 while suppressing the temperature rise of the control element.
4 can reduce the operation time. Therefore, it is possible to achieve a reduction in operating noise during rice cooking, and it is not necessary to employ an expensive cooling fan 24 having a long service life, so that a small and inexpensive cooling fan 24 can sufficiently achieve its purpose. As a result, the space occupied by the cooling fan 24 can be reduced, and power consumption can be reduced. In addition, in the case of the present embodiment, after the cooling fan 24 is started to operate, the operation is continued until the cooking is completed, so that the annoying sound due to the repeated start and stop of the cooling fan 24 is eliminated.

Fourth Embodiment FIG. 12 shows the contents of a control circuit for a cooling fan in an electromagnetic rice cooker according to a fourth embodiment of the present invention.

In the case of the present embodiment, the cooling fan 24 is of a variable air flow type (in other words, a variable cooling capacity type) (that is, one that can be operated in three types of air flow modes of weak, medium and strong). And three types of operation start control means 48A, 48B, 48C are provided. Then, the operation start control unit 48A determines that the temperature T ₁ detected by the element temperature sensor 23 is the first set temperature Ts ₁ (for example, 10
0 °), the operation of the cooling fan 24 is started, and the operation start setting means 48B determines that the temperature T ₁ detected by the element temperature sensor 23 is equal to the second set temperature Ts.
₂ (for example, 115 ° C.), the operation of the cooling fan 24 is started, and the operation start setting means 48C
Operates to start the operation of the cooling fan 24 when the temperature T ₁ detected by the element temperature sensor 23 reaches the third set temperature Ts ₃ (for example, 125 ° C.). The operation stop of the cooling fan 24 is performed by the operation stop control means 50 when the inner pot temperature T ₂ detected by the center sensor 9 reaches a predetermined temperature (for example, a cooking temperature) T ₀ . Other configurations are the same as in the first embodiment.

Next, the operation control of the cooling fan 24 in the electromagnetic rice cooker according to the present embodiment will be described with reference to the flowchart shown in FIG. 13 and the time chart shown in FIG.

In step S ₁ , a standby mode is set (that is, a mode in which rice cooking can be started).
When the ON operation of the cooking switch (not shown) is confirmed in _2, heated by work coil 18 is started in step S _3, enters the water absorption step, steps are performed up cooking in step S _4. Then, step S ₅
Comparison between the detection temperature T ₁ of the first set temperature Ts ₁ by the element temperature sensor 23 is made at. The detected temperature T
₁ is a control element (for example, a power transistor 2) that generates heat by controlling the energization of the work coil 18 during rice cooking.
1 and the temperature of the rectifying diode bridge 22), which rises with the progress of rice cooking (see FIG. 14). Here, if it is determined that T ₁ <Ts ₁ , the temperature T ₂ detected by the center sensor 9 is compared with the cooking temperature T ₀ in step S ₆ , and if T ₂ ≧ T ₀ (that is,
In this case) have ended up cooked, the operation of the cooling fan 24 in step S ₇ without started, then proceeds to steaming step and incubating process proceeds to step S ₈ and step S _9. The operation stop is executed by the operation stop control means 50 in the cooling fan control circuit 47. Incidentally, if the determination is in the negative in step S ₇ A (i.e., if it is determined not to reach the temperature raised cooking), the process returns to step S _4.

[0065] On the other hand, when it is determined that T ₁ ≧ Ts in step S _5, the element temperature sensor 2 in step S ₁₀
3 the detection temperatures T ₁ by comparison with the second set temperature Ts ₂ is made, T ₁ <Ts ₂ (In other _{words, Ts 1 ≦ T 1 <Ts} 2)
And when it is determined, the weak mode operation of the cooling fan 24 is started in step S _11, then step S ₇
Proceed to. The operation start is executed by the operation start control means 48A in the cooling fan control circuit 47.

[0066] radiating plate 20 and a control element (e.g., a power transistor 21 and the rectifier diode bridge 22) by the weak mode operation of the cooling fan 24 described above, but is cooled by lowering the temperature, T ₂ ≧ In step S ₇
(In other words, until the completion of raising cooked) until it is determined that T ₀ is the weak mode operation of the cooling fan 24 is continued.

[0067] The determination despite the weak mode operation of the cooling fan 24, the control element (e.g., a power transistor 21 and the rectifier diode bridge 22) temperature does not drop in a T ₁ ≧ Ts ₂ in step S ₁₀ Once, the process proceeds to step S _12, compared with the detected temperatures T ₁ and the third set temperature Ts ₃ by the element temperature sensor 23 is made, T
(In other _{words, Ts 2 ≦ T 1 <Ts} 3) 1 <Ts 3 when it is determined that in step S ₁₃ is started mode operation in the cooling fan 24, then proceeds to step S _7.
The operation start is executed by the operation start control means 48B in the cooling fan control circuit 47.

[0068] the above-mentioned heat radiating plate 20 and the control element by mode operation in the cooling fan 24 (e.g., a power transistor 21 and the rectifier diode bridge 22), but is cooled by lowering the temperature, T ₂ ≧ In step S ₇
Until it is determined as T ₀ (in other words, until the cooking is completed), the middle mode operation of the cooling fan 24 is continued.

[0069] Then, despite the mode operation in the cooling fan 24, the control element (e.g., a power transistor 21 and the rectifier diode bridge 22) without lowering the temperature of, determines that T ₁ ≧ Ts ₃ in step S ₁₂ Once, the process proceeds to step S _14, started strong mode operation of the cooling fan 24, then proceeds to step S _7. The start of the operation is executed by the operation start control means 48C in the control circuit 47 for the cooling fan.

[0070] the above-mentioned heat radiating plate 20 and the control element by strong mode operation of the cooling fan 24 (e.g., a power transistor 21 and the rectifier diode bridge 22), but is cooled by lowering the temperature, T ₂ ≧ In step S ₇
Until T ₀ is determined (in other words, until the end of cooking), the strong mode operation of the cooling fan 24 is continued.

If a negative determination is made in step S ₂ , the ON operation of the heat retention / cancel switch (not shown) is confirmed in step S ₁₅ , and if an affirmative determination is made, the process proceeds to step S ₉ to keep the temperature. proceeds to step returns to step S ₁ when a negative determination is made.

That is, the temperature T ₁ detected by the element temperature sensor 23 is the first, second and third set temperatures Ts ₁ , Ts
When the cooling fan 24 reaches s ₂ and Ts ₃ , the cooling fan 24 is operated in the weak mode, the medium mode and the strong mode (see FIG. 14) corresponding to the respective set temperatures, and the element temperature T ₁
Of the control element (for example, the power transistor 2) that generates heat.
Thus, further noise reduction can be achieved while preventing breakage of the rectifier diode bridge 22) due to a rise in temperature.

Fifth Embodiment FIGS. 15 to 17 show an electromagnetic rice cooker according to a fifth embodiment of the present invention.

In the case of the present embodiment, the heat radiating plate 20 supporting the control element that generates heat (that is, the power transistor 21 and the rectifying diode bridge 22) is connected to the container main body 1.
A plate-shaped main body 20a having a shape along the inner surface of the side wall (in other words, the inner surface of the outer case 5) and made of a good thermal conductor (for example, aluminum material), Fins 20b, 20b extending in the direction
, And is attached to a mounting boss 19a integrally projecting from the ferrite core 19 at a rear side peripheral portion 4b in the space portion 4 of the container main body 1 with a screw 50. Since the rear side peripheral portion 4b of the space portion 4 has a relatively large surplus space, it is suitable for disposing the heat radiating plate 20. By effectively using this surplus space, the container The outer diameter of the main body 1 does not need to be increased. Further, the power transistor 21 and the rectifying diode bridge 22 are directly attached to both the inner and outer surfaces of the lower end portion of the heat sink main body 20a by bolts 51 in a co-tightened state. In the case of this embodiment, the element temperature sensor 23 is also fastened by the bolt 51.

With such a configuration, the power transistor 21, the rectifying diode bridge 22, and the radiating plate 20 are exposed to an airflow that naturally convects from below to above in the space 4 of the container body 1. The equipment will be naturally cooled by the convection airflow.
At this time, the radiation fins 20b, 20b on the radiation plate 20
.. the heat radiation fins 2
.. And the convection airflow are increased.

Further, a cooling fan 24 is provided below the mounting position of the heat radiating plate 20 while being supported by a supporting plate 52. The air inlet 27 is formed directly below the cooling fan 24 and formed at the bottom of the outer case 5, while the air outlet 28 is formed at a position above the heat radiation plate 20 on the peripheral wall of the outer case 5. Air outlet 2
Even if a metal pin or the like is mistakenly inserted from step 8, there is no risk of electric shock.

Further, in this embodiment, a black coating 53 made of a black paint or a black oxide coating is formed on the surface of the heat sink 20 as shown in FIG. Due to the formation of the black film 53, the amount of radiated heat radiation from the heat radiating plate 20 increases, and the cooling of the power transistor 21 and the rectifying diode bridge 22 can be more effectively obtained.

With the above configuration, in this embodiment, the temperature T ₁ detected by the element temperature sensor 23 does not easily rise to the operation start temperature Ts of the cooling fan 24 due to the heat radiation effect of the heat radiation plate 20. Since the operation start of the cooling fan 24 can be delayed as much as possible and a rapid temperature decrease can be obtained after the operation of the cooling fan 24 is started, the embodiment 1 or the embodiment 2 so that the earlier even shutdown time of the cooling fan 24 in which to stop the operation of the cooled fan 24 by the temperature decrease of the element temperature T ₁ of, as in.
That is, the operation time of the cooling fan 24 can be reduced as much as possible.

Other structures, functions and effects are the same as those of the first to third embodiments.
Since it is the same as the fourth embodiment, the description is omitted to avoid duplication.

Sixth Embodiment FIG. 18 shows an electromagnetic rice cooker according to a sixth embodiment of the present invention.

In the case of this embodiment, the air suction port 27 is formed on the side wall of the outer case 5 below the air outlet 28 and below the heat radiating plate 20. With such a configuration, it is possible to prevent electric shock when a pin or the like is inserted from the air inlet 27 or the air outlet 28. Other configurations and operational effects are the same as those described in the first to fifth embodiments.

Seventh Embodiment FIG. 19 shows an electromagnetic rice cooker according to a seventh embodiment of the present invention.

In the case of the present embodiment, the heat radiating plate 20 is disposed at the rear corner 4 c in the space 4 of the container body 1. Since the rear corner portion 4c also has a relatively large excess space, it is suitable for arranging the heat radiating plate 20, and by effectively utilizing the excess space, the outer diameter of the container body 1 is reduced. Need not be increased. Other configurations and operational effects are the same as those described in the first to fifth embodiments.

Eighth Embodiment FIG. 20 shows an electromagnetic rice cooker according to an eighth embodiment of the present invention.

In the case of this embodiment, the heat radiating plate 20 is disposed at the front corner 4 d in the space 4 of the container body 1. Therefore, in this embodiment, the mounting member 36 for mounting the microcomputer board 37 is half the size of the first embodiment. The power transistor 21 and the rectifying diode bridge 22 are connected to separate volts 51,
The temperature sensor 23 is fixed together with the power transistor 21. This front corner 4d
Also, since it has a relatively large excess space, it is suitable for arranging the heat sink 20. By effectively using this excess space, it is possible to increase the outer diameter of the container body 1 without increasing the outer diameter. Get better. Other configurations and operational effects are the same as those described in the first to fifth embodiments.

In the above embodiment, the power transistor 21 and the rectifying diode bridge 22 are attached to the heat sink 20. However, the heat sink 20 may be attached only to the power transistor 21 that generates the most heat. The power transistors are IGBT, FE
A switching element such as T or triac may be used.

The present invention is not limited to the configuration of each of the above embodiments, and it is needless to say that the design can be changed as appropriate without departing from the gist of the invention.

[Brief description of the drawings]

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

FIG. 2 is a circuit configuration diagram showing a power supply circuit in the electromagnetic rice cooker according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing the contents of a control circuit for a cooling fan in the electromagnetic rice cooker according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating an operation of a control circuit for a cooling fan in the electromagnetic rice cooker according to the first embodiment of the present invention.

FIG. 5 is a time chart for explaining the operation of the control circuit for the cooling fan in the electromagnetic rice cooker according to the first embodiment of the present invention.

FIG. 6 is a circuit diagram showing a power supply circuit in the electromagnetic rice cooker according to the second embodiment of the present invention.

FIG. 7 is a block diagram showing the contents of a control circuit for a cooling fan in the electromagnetic rice cooker according to the second embodiment of the present invention.

FIG. 8 is a flowchart illustrating an operation of a control circuit for a cooling fan in the electromagnetic rice cooker according to the second embodiment of the present invention.

FIG. 9 is a block diagram illustrating a cooling fan control circuit in the electromagnetic rice cooker according to the third embodiment of the present invention.

FIG. 10 is a flowchart illustrating an operation of a control circuit for a cooling fan in the electromagnetic rice cooker according to the third embodiment of the present invention.

FIG. 11 is a time chart for explaining the operation of the control circuit for the cooling fan in the electromagnetic rice cooker according to the third embodiment of the present invention.

FIG. 12 is a block diagram showing the contents of a control circuit for a cooling fan in an electromagnetic rice cooker according to a fourth embodiment of the present invention.

FIG. 13 is a flowchart illustrating an operation of a control circuit for a cooling fan in the electromagnetic rice cooker according to the fourth embodiment of the present invention.

FIG. 14 is a time chart illustrating the operation of the control circuit for the cooling fan in the electromagnetic rice cooker according to the fourth embodiment of the present invention.

FIG. 15 is a longitudinal sectional view of an electromagnetic rice cooker according to a fifth embodiment of the present invention.

16 is a sectional view taken along the line XVI-XVI in FIG.

FIG. 17 is a partially enlarged cross-sectional view of a heat sink in an electromagnetic rice cooker according to a fifth embodiment of the present invention.

FIG. 18 is a longitudinal sectional view of an electromagnetic rice cooker according to a sixth embodiment of the present invention.

FIG. 19 is a cross-sectional view (corresponding to FIG. 15) of the electromagnetic rice cooker according to the seventh embodiment of the present invention.

FIG. 20 is a cross-sectional view (corresponding to FIG. 15) of the electromagnetic rice cooker according to the eighth embodiment of the present invention.

[Explanation of symbols]

1 is a container body, 3 is an inner pan, 4 is a space portion, 4a is a front side peripheral portion, 4b is a rear side peripheral portion, 4c is a rear side corner portion,
d is the front corner, 5 is the outer case, 6 is the inner case, 6
a is a cylindrical case, 6b is a dish-shaped case, 8 is a heat retention heater,
9 is an inner pot temperature detecting means (center sensor), 18 is a work coil, 19 is a ferrite core, 19a is a mounting boss,
Reference numeral 20 denotes a radiator plate, 20a denotes a radiator plate, 20b denotes a radiator fin, 21 denotes a control element (power transistor), 22 denotes a control element (rectifier diode bridge), 23 denotes element temperature detecting means (element temperature sensor), and 24 denotes Cooling means (cooling fan), 27 is an air inlet, 28 is an air outlet, 38
Is a heat insulating material, 39 is a heat shield plate, 47 is a control circuit for a cooling fan, 48, 48A to 48B are operation start control means, 49,
50 is operation stop control means.

Continuation of the front page (56) References JP-A-7-289419 (JP, A) JP-A-7-289421 (JP, A) JP-A-62-269479 (JP, A) JP-A-3-114188 (JP) , A) Japanese Utility Model Application No. 3-58219 (JP, U) Japanese Utility Model Application No. 4-35396 (JP, U) Japanese Utility Model Application No. Sho 61-145492 (JP, U) Japanese Utility Model Application No. Sho 62-139096 (JP, U) (58) Surveyed field (Int. Cl. ⁶ , DB name) A47J 27/00 103 A47J 27/00 109

Claims (7)

(57) [Claims] 1. An inner pot temperature detecting means for detecting a temperature of the inner pot, comprising: a container body configured to accommodate an inner pot heated by high-frequency electromagnetic induction by a work coil; a control element for controlling the energization of the control device an electromagnetic cooker provided with the cooling means for cooling, and the element temperature detection means for detecting the temperature of the control element, the element temperature detection Detected by means
And operation start control means for starting the operation of the time or we said cooling means element temperature has reached the set temperature, the inner bowl temperature detecting means
When the inner pot temperature detected by the
An electromagnetic rice cooker provided with operation stop control means for stopping operation of the cooling means . 2. An element temperature is detected by said element temperature detecting means.
2. The control device according to claim 1, further comprising a second operation stop control unit for stopping the operation of the cooling unit when the element temperature decreases by a predetermined temperature by the start of the operation of the cooling unit. Electromagnetic rice cooker. Wherein it sets more operation start becomes the set temperature stepwise increase of the cooling unit by the operation start control means increases said to correspond to the operation start set temperature stepwise as cooling means more claim 1 and an electromagnetic cooker of any one of claims 2, characterized in that the employed having a cooling capacity. 4. The control element is attached to a heat radiating plate made of a good heat conductor, and the heat radiating plate is arranged in a side peripheral portion in a space of the container body and has a large number of heat radiating fins extending in a vertical direction. The electromagnetic rice cooker according to any one of claims 1 to 3 , wherein: 5. The electromagnetic rice cooker according to claim 4, wherein a black film is formed on a surface of the heat sink. 6. The electromagnetic cooker according to any one claim of the claims 4 and 5, characterized in that arranged heat shield plate on the inner side of the radiator. 7. The electromagnetic rice cooker according to claim 6, wherein a heat insulating material is provided inside the heat shield plate.