JP3225209B2 - rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rice cooker in which a lid is detachably attached to a rice cooker main body.

[0002]

2. Description of the Related Art As shown in FIG. 4, a rice cooker 1 of this type includes a lid 3 with respect to a rice cooker body 2 in which an inner pot 8 is arranged.
Are provided so that the cover 3 is detachably attached to the cover 3 to improve the convenience of handling when cleaning the cover 3 and the like. In such a rice cooker 1, the wiring between the rice cooker main body 2 and the lid 3 cannot be performed, so that the primary coil 4 is attached to the shoulder 2 a of the rice cooker main body 2.
At the same time, the secondary coil 5 is attached to the edge 3a on the side of the lid 3 facing the shoulder 2a, and when the primary coil 4 is energized, the secondary coil 5 is generated by the mutual induction action. The heater 6 as a load component attached to the lid 3 is heated and uneven by electric power so that the functions of keeping heat and skipping the soup are operated.

[0003]

However, in the rice cooker 1, with the rice cooker body 2 and the lid 3 attached, a metal such as aluminum foil is placed between the shoulder 2a and the edge 3a. When the piece 7 enters, there is a disadvantage that the electromagnetic induction between the primary coil 4 and the secondary coil 5 cannot be sufficiently performed, and the generated electromotive force is insufficient. Further, when the metal piece 7 generates heat by induction heating, there is a possibility that the peripheral shoulder 2a and the edge 3a made of resin may be deformed. In addition,
Even when the lid 3 is not attached to the rice cooker main body 2 in a predetermined attachment state, the generated electromotive force may be insufficient as described above.

Therefore, in the present invention, it is detected whether or not a metal piece has entered between the rice cooker main body and the lid, and if the metal piece has entered, at least the supply of power to the lid is stopped. Another object of the present invention is to make it possible to detect whether the lid is attached to the rice cooker main body in a predetermined attachment state.

[0005]

In order to solve the above problems, a first aspect of the present invention is a rice cooker, in which a lid is detachably attached to a rice cooker main body, and the rice cooker main body is connected to an AC power supply. A DC power supply circuit comprising a rectifier circuit and a smoothing capacitor connected to the output side of the rectifier circuit; and an electromagnetic induction circuit having a primary coil and switching means connected to the DC power supply circuit. A rice cooker in which a lid-side load control circuit including a secondary coil and a load component is disposed on a body, and an electromotive force generated in the secondary coil by electromagnetic induction from the primary coil is supplied to the load component. A voltage detecting circuit for detecting a voltage at both ends of the smoothing capacitor; and abnormality determining means for determining an abnormality in the mounting state of the lid based on the voltage detected by the voltage detecting circuit.

A rice cooker as a second means is characterized in that a lid is detachably attached to the rice cooker main body, and a rectifier circuit connected to an AC power supply and a smoother connected to an output side of the rectifier circuit. A DC power supply circuit comprising a capacitor and an electromagnetic induction circuit having a primary coil and switching means connected to the DC power supply circuit, while a lid-side load comprising a secondary coil and a load component is provided on the lid. In a rice cooker provided with a control circuit and supplying an electromotive force generated in the secondary coil by electromagnetic induction from the primary coil to the load component, a voltage detection circuit for detecting a voltage at both ends of the primary coil And abnormality determination means for determining an abnormality in the mounting state of the lid based on the voltage detected by the voltage detection circuit.

According to the rice cooker, since the voltage detecting circuit is connected to the smoothing capacitor or the primary coil, a case where a metal piece enters between the primary coil and the secondary coil, When the cover is not attached to the main body in a predetermined attachment state, the voltage detected by the voltage detection circuit fluctuates, so that abnormality in the attachment state of the lid can be determined by the abnormality determination unit. Therefore, it is possible to prevent the lid from operating in a state of insufficient power.

[0008] In the rice cooker according to the second means, the primary coil comprises two induction coils, and the voltage detection circuit comprises a first and a second induction coil forming a bridge circuit together with the first and second induction coils. A second resistor, and an oscillation circuit for supplying a high-frequency current to the bridge circuit;
It is preferable to detect a voltage between the first induction coil and the first resistor and a voltage between the second induction coil and the second resistor.

A two-contact type first relay is disposed between a first induction coil and a second induction coil of the primary coil, and the electromagnetic induction circuit is connected to a first contact of the first relay. While connecting the oscillator circuit to the second contact portion,
It is preferable to connect the primary coil to the electromagnetic induction circuit after detecting the voltage by the voltage detection circuit and determining that there is no abnormality by the abnormality determination means.

Further, a two-contact type second relay and a third relay are disposed on the output side of the first induction coil and the second induction coil of the primary coil, respectively, and the first and second relays of the second and third relays are provided. Connecting the electromagnetic induction circuit to a contact portion, connecting the first and second resistors to a second contact portion,
It is more preferable that no voltage is applied to the voltage detection circuit side while connected to the electromagnetic induction circuit.

In each of the rice cookers, the abnormality determination means is a microcomputer, and the microcomputer compares a voltage detected by the voltage detection circuit with a threshold to supply power to a load component of the lid. Is preferably controlled. Alternatively, the abnormality determination means includes a comparator and a microcomputer, compares the voltage detected by the comparator with the voltage detection circuit with a preset threshold, and inputs a comparison signal to the microcomputer, The microcomputer may control the supply of power to the load components of the lid. In this way, when a metal piece enters between the primary coil and the secondary coil, the disadvantage that the metal piece is induction-heated and the resin around the metal piece is deformed can be avoided.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an electric circuit 10 of a rice cooker according to a first embodiment of the present invention. The structure of the rice cooker is shown in FIG.
Therefore, FIG. 4 will be referred to in the following description.

The electric circuit 10 includes an electromagnetic induction circuit 11 having a primary coil 4 for supplying power to the lid 3 side.
A lid-side load circuit 12 that supplies the electromotive force generated in the secondary coil 5 by the electromagnetic induction circuit 11 to the heater 6 as a load component; a voltage detection circuit 13; Abbreviated as microcomputer.)
14. In addition, the rice cooker main body 2 includes an induction heating circuit (not shown) for induction heating the inner pot 8.

The electromagnetic induction circuit 11 is a DC power supply comprising a rectifier circuit 17 connected to an AC power supply 15 via a relay 16, and a smoothing capacitor 18 and a choke coil 19 connected to the output side of the rectifier circuit 17. Circuit.

Minus (-) of the choke coil 19
The side is branched into two, and one is a shoulder 2 of the rice cooker main body 2.
a is connected to the primary coil 4 and the other is connected to the resistor 21. The primary coil 4 includes two induction coils 20A and 20B, and the choke coil 19 is connected to a connection between these coils.

The negative (-) side of the first induction coil 20A is connected to the collector pole c of the first transistor 23 which is a switching element. Similarly, the negative (-) side of the second induction coil 20B is connected to the collector pole c of the second transistor 24, which is a switching element. The first and second transistors 23,
A resonance capacitor 22 is connected between the 24 collector poles c. The emitter poles e are each grounded.

The negative (-) side of the resistor 21 is connected to a capacitor 27, and the negative (-) side of the capacitor 27 is grounded. The negative (−) side of the resistor 21 is connected to the base pole b of the first transistor 23 via a resistor 25 and to the base pole b of the second transistor via a resistor 26. Have been. These first and second transistors 23, 2
A coil 28 is connected to the four base poles b so that they do not have the same potential. A first and a second transistor 2 are provided at both ends of the capacitor 27.
A diode 30 for preventing the base poles b of the 3 and 24 from becoming negative, and a coil 29 connected in series to the diode 30 are connected.

The cover-side load circuit 12 includes a secondary coil 5 disposed on an edge 3a of the cover 3 so as to face the primary coil 4, and a load component connected to the secondary coil. And a heater 6.

The voltage detection circuit 13 is connected in parallel to both ends of the smoothing capacitor 18, and the output side thereof is connected to the microcomputer 14. That is, when the metal piece 7 enters between the primary coil 4 and the secondary coil 5 or when the lid 3 is not attached to the rice cooker main body 2 in a predetermined attachment state, the smoothing capacitor 18 Abnormality is detected using the fluctuation of the voltage between both ends.

The microcomputer 14 includes the voltage detection circuit 1
3 to determine whether or not the initial waveform of the voltage detected is within the set range of the set threshold value, and sends a signal to the relay 16 of the electromagnetic induction circuit 11 to supply power to the lid 3. To control. In the present embodiment, the voltage waveform when the rice cooker 1 is operated in a state where the metal piece 7 does not enter between the primary coil 4 and the secondary coil 5 at the time of manufacturing the rice cooker 1 (shown by a solid line A in FIG. 2). And a value slightly lower than the lower limit of the voltage waveform (indicated by the solid line C in FIG. 2) when the lid 3 is not mounted is set in the microcomputer 14 as a threshold. An abnormality is determined based on whether the lower limit value of the waveform is within the threshold value.

Next, the operation of the rice cooker 1 equipped with the electric circuit 10 will be described. First, the microcomputer 14 turns on the relay 16 during the rice cooking and warming operation. As a result, AC power flows through the rectifier circuit 17 and the rectifier circuit 17
As a result, AC power is converted to DC power.

Then, the output from the rectifier circuit 17 is smoothed by the smoothing capacitor 18 and the coil 19, and the first and second transistors 23 and 24 are alternately switched by the action of the coils 28 and 29. A high-frequency current flows through the primary coil 4. Thus, an AC electromotive force is generated in the secondary coil 5 by an electromagnetic induction action, and the heater 6 is heated by the electromotive force.

When the heater 6 operates, an initial voltage of the smoothing capacitor 18 is measured by the voltage detection circuit 13, and the voltage is input to the microcomputer 14.
Then, the microcomputer 14 detects an abnormality by comparing the input voltage with a set threshold value. That is, the metal piece 7 such as an aluminum foil does not enter between the primary coil 4 of the rice cooker main body 2 and the secondary coil 5 of the lid 3, and the lid 3 is securely attached to the rice cooker main body 2. In the case of the attached normal state, the voltage across the smoothing capacitor 18 measured by the voltage detection circuit 13 shows a voltage waveform that does not exceed the threshold as shown by a solid line A in FIG. Therefore, microcomputer 1
An off signal is not transmitted to the relay 16 via 4 and the electromagnetic induction circuit 11 is energized, so that the electromagnetic induction to the secondary coil 5 is continued.

On the other hand, when the metal piece 7 is inserted between the primary coil 4 of the rice cooker main body 2 and the secondary coil 5 of the lid 3, the voltage across the smoothing capacitor 18 becomes FIG. 2 shows a voltage waveform whose lower limit exceeds the lower limit of the threshold, as indicated by a dashed line B. in this way,
When the threshold value set in the microcomputer 14 is exceeded, an off signal is transmitted from the microcomputer 14 to the relay 16, and the power supply to the electromagnetic induction circuit 11 of the rice cooker main body 2 is stopped so that the power to the lid 3 is reduced. Stop supplying.

When the lid 3 is not attached to the rice cooker main body 2, the voltage at both ends of the smoothing capacitor 18 is in a normal state as shown by a broken line C in FIG. A voltage waveform having a lower limit higher than the lower limit exceeds the upper limit of the threshold. As a result, an off signal is transmitted from the microcomputer 14 to the relay 16 as described above, and the supply of power to the lid 3 is stopped.

As described above, in the rice cooker 1 equipped with the electric circuit 10, when the metal piece 7 enters between the primary coil 4 of the rice cooker main body 2 and the secondary coil 5 of the lid 3. Since the supply of power to the lid 3 is stopped, it is possible to prevent a problem that the metal piece 7 generates heat due to electromagnetic induction and deforms the surrounding resin material. In addition, since it is possible to detect a case where the lid 3 is not securely attached to the rice cooker main body 2, the rice cooker 1 can always be operated in a normal state.

FIG. 3 shows an electric circuit 35 of the rice cooker 1 of the second embodiment. The electric circuit 35 includes an electromagnetic induction circuit 36,
It comprises a lid-side load circuit 12, a voltage detection circuit 37, comparators 46 and 47 and a microcomputer 14 which constitute abnormality determination means. The electric circuit 35 includes a primary coil 4
For example, when the metal piece 7 is inserted between the primary coil 4 and the secondary coil 5, it is possible to detect an abnormality in the mounting state of the lid 3 by using the change in the high-frequency resistance of the primary coil 4. This is particularly different from the first embodiment.

The electromagnetic induction circuit 36 is the same as the electromagnetic induction circuit 11 of the first embodiment, except for the first and second electromagnetic induction circuits.
The primary coil 4 composed of the induction coils 20A and 20B has 2
A contact type first relay 38, a second relay 39, and a third relay 40 are provided, and the primary coil 4 can be switched between the electromagnetic induction circuit 36 side and the voltage detection circuit 37 side by these relays 38, 39, 40. The only difference is that you can connect to

That is, the minus (-) side of the choke coil 19 is connected to the first induction coil 20A and the second induction coil 2A.
0B, the first contact portion 3 of the first relay 38 disposed at the connection portion
8a. The collector pole c of the first transistor 23 is connected to the first contact 39a of the second relay 39, and the collector c of the second transistor 24 is connected to the first contact 40a of the third relay 40.

The voltage detection circuit 37 generally comprises an oscillation circuit 42, an amplification circuit 43, and first and second resistors 44 and 45. Specifically, the oscillating circuit 42 supplies a high frequency of about 900 kHz to the primary coil 4 together with the amplifying circuit 43, and its output section is connected to the first relay 38.
Of the second contact portion 38b.

The first resistor 44 is connected to the second relay 3
9 is connected to the second contact portion 39b, and its negative (-) side is grounded. Similarly, the second resistor 45 is connected to the second contact portion 40b of the third relay 40, and the minus (-) side is grounded. In the present embodiment, the first and second resistors 44 and 45 form a bridge circuit together with the induction coils 20A and 20B.

The comparator 46 constituting the abnormality determination means,
47 is an operational amplifier. The negative electrode side of the comparator 46 is connected between the first induction coil 20A and the first resistor 44. Further, the voltage division of the resistors 48 and 49 connected to the reference voltage supply circuit is input to the positive electrode side of the comparator 46 as a threshold value. Similarly, the comparator 47
Is connected to the second induction coil 20B and the second resistor 4B.
5 is connected. Resistors 50 and 51 connected to a reference voltage supply circuit are provided on the positive side of the comparator 47.
Is input as a threshold value.

The output terminals of the comparators 46 and 47 are connected to the microcomputer 14 after being connected to one line.
It is connected to a reference voltage supply circuit serving as a threshold via a resistor 54 and is grounded via a capacitor 55.

Next, the operation of the rice cooker 1 equipped with the electric circuit 35 having the voltage detection circuit 37 will be described.
First, the microcomputer 14 operates the relay 16 during the cooking and warming operation.
Before turning ON the first relay 38, the second relay 39 and the third relay 40 are connected to the second contact portions 38b, 39b and 40b by the microcomputer 14, respectively, and the oscillation circuit 42 is connected via the amplification circuit 43. As a result, a high-frequency current flows through the first induction coil 20A and the second induction coil 20B of the primary coil 4.

The primary coil 4 and the secondary coil 5
When the metal piece 7 does not enter between them, the high-frequency resistance of the induction coils 20A, 20B does not fluctuate, so that these induction coils 20A, 20B and the resistors 44, 4
5 is maintained in a balanced state, and a voltage smaller than the threshold value of each positive electrode is input to the negative electrodes of the comparators 46 and 47.

As a result, the comparators 46 and 47 output the H signal from the output terminals, and the microcomputer 14 receives the H signal. Then, the microcomputer 14 determines that the metal piece 7 has not entered based on the input H signal, and transmits a signal to each of the relays 38, 39, 40 to connect to the first contact portions 38a, 39a, 40a, respectively. And the primary coil 4 is connected to the electromagnetic induction circuit 36 side. The operation of the electromagnetic induction circuit 36 is the same as that of the first embodiment.

On the other hand, between the primary coil 4 and the secondary coil 5, the first induction coil 20A of the primary coil 4 and the second
When the metal piece 7 enters one or both of the induction coils 20B, these induction coils 20B
The high-frequency resistance of A and 20B fluctuates, and the balance of the bridge circuit is broken. That is, the voltage input to one or both of the negative electrodes of the comparators 46 and 47 changes, and a voltage higher than the threshold value is input.
An L signal is output from 47, and the L signal is input to the microcomputer 14.

As a result, the microcomputer 14 receives the input L
It is determined by the signal that the metal piece 7 has entered, and an off signal is transmitted to the relay 16 to stop energizing the electromagnetic induction circuit 36. In addition, even when the lid 3 is not attached to the rice cooker main body 2 in a predetermined state, the high-frequency resistance fluctuates similarly to the case where the metal piece 7 enters, and an abnormality can be detected.

As described above, the electric circuit 35 of the second embodiment
In the same manner as in the first embodiment, it is possible to detect an abnormality such as when the metal piece 7 has entered or when the lid 3 is not attached in a predetermined state. Further, in the second embodiment, the relays 38, 39, and 40 are connected to the first induction coil 20A and the second induction coil 20B constituting the primary coil 4.
40 is attached so as to be switchably connected to the electromagnetic induction circuit 36 side and the voltage detection circuit 37 side. It is possible to prevent the voltage detection circuit 37 from being damaged due to the application of a voltage.

The rice cooker according to the present invention is not limited to the above-described configuration. For example, in each of the above embodiments, only the supply of power to the lid 3 is stopped by the relay 16, but the supply of power to the entire rice cooker 1 may be stopped.

[0041]

As is apparent from the above description, in the rice cooker of the present invention, the supply of power to the lid is detected by detecting an abnormality in the state of attachment of the lid to the rice cooker main body by the voltage detection circuit. Since the operation of the rice cooker is stopped, it is possible to prevent a failure in energization and prevent the primary coil and the secondary coil from generating heat and deforming peripheral components, thereby improving the reliability of the rice cooker itself.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram mounted on a rice cooker according to a first embodiment of the present invention.

FIG. 2 is a graph showing a voltage waveform at a smoothing capacitor of the electric circuit of FIG.

FIG. 3 is an electric circuit diagram mounted on a rice cooker according to a second embodiment.

FIG. 4 is a cross-sectional view of a rice cooker in which a lid is detachably attached to a rice cooker main body.

[Explanation of symbols]

1 ... rice cooker, 2 ... rice cooker body, 2a ... shoulder, 3 ... lid,
3a: Edge, 4: Primary coil, 5: Secondary coil, 6: Heater, 7: Metal piece, 10, 35: Electric circuit, 11, 36
... Electromagnetic induction circuit, 12 ... Lid side load circuit, 13,37 ...
Voltage detection circuit, 14: microcomputer, 15: AC power supply, 17
... Rectifier circuit, 18 ... Smoothing capacitor, 20A, 20B ...
Induction coils, 23, 24 ... transistors, 38, 39,
40 relay, 42 oscillator circuit, 43 amplifier circuit, 4
6, 47 ... Comparator.

Continuation of the front page (72) Inventor Minoru Sasaki 1-20-5 Tenma, Kita-ku, Osaka-shi, Osaka Zojirushi-Mahobin Co., Ltd. (56) References JP-A-5-68634 (JP, A) JP-A-8 −154814 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A47J 27/00 103 A47J 27/00 109 H05B 6/12

Claims (7)

(57) [Claims] A DC power supply circuit comprising a rectifier circuit connected to an AC power supply and a smoothing capacitor connected to an output side of the rectifier circuit, the lid body being detachably attached to the rice cooker main body, An electromagnetic induction circuit having a primary coil connected to a DC power supply circuit and switching means is provided, while a lid-side load control circuit comprising a secondary coil and a load component is provided on the lid, and In a rice cooker supplying an electromotive force generated in the secondary coil to the load component by electromagnetic induction from a coil, a voltage detection circuit for detecting a voltage across the smoothing capacitor, and a voltage detected by the voltage detection circuit. A rice cooker comprising: an abnormality determination unit configured to determine abnormality in an attached state of the lid based on the abnormality. 2. A DC power supply circuit comprising a rectifier circuit connected to an AC power supply and a smoothing capacitor connected to an output side of the rectifier circuit. An electromagnetic induction circuit having a primary coil connected to a DC power supply circuit and switching means is provided, while a lid-side load control circuit comprising a secondary coil and a load component is provided on the lid, and In a rice cooker for supplying an electromotive force generated in the secondary coil to the load component by electromagnetic induction from a coil, a voltage detection circuit for detecting a voltage at both ends of the primary coil, and a voltage detected by the voltage detection circuit A rice cooker provided with abnormality determination means for determining an abnormality in the state of attachment of the lid based on the condition. 3. The primary coil includes two induction coils, and the voltage detection circuit includes a first induction coil and a second induction coil.
A first and a second resistor forming a bridge circuit together with an induction coil; and an oscillating circuit for supplying a high-frequency current to the bridge circuit, wherein the first and second resistors are arranged between the first induction coil and the first resistor. The rice cooker according to claim 2, wherein a voltage between the induction coil and the second resistor is detected. 4. A first induction coil and a second induction coil of the primary coil.
A two-contact type first relay is provided between the first relay and the induction coil, and the electromagnetic induction circuit is connected to the first contact of the first relay, and the oscillation circuit is connected to the second contact. The rice cooker according to claim 3, characterized in that: 5. A first induction coil of the primary coil and a second induction coil.
A two-contact type second relay and a third relay are respectively provided on the output side of the induction coil, and the electromagnetic induction circuit is connected to the first contact portions of the second and third relays.
The rice cooker according to claim 3 or 4, wherein the first and second resistors are connected to a contact portion. 6. The abnormality determination means is a microcomputer, and controls supply of power to a load component of the lid by comparing a voltage detected by the voltage detection circuit with a threshold value by the microcomputer. Claim 1
The rice cooker according to claim 5. 7. The abnormality judging means comprises a comparator and a microcomputer. The comparator compares a voltage detected by the voltage detection circuit with a preset threshold value and sends a comparison signal to the microcomputer. type in,
The rice cooker according to any one of claims 1 to 5, wherein supply of electric power to a load component of the lid is controlled by the microcomputer.