JP2004275645A - Electric rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric rice cooker which is more safe by surely detecting the abnormality of a heating means and informing a user of the abnormality. <P>SOLUTION: When detected current detected by a current detection means when the heating means is turned on by a control circuit in a period until starting rice cooking after supplying power is not higher than a prescribed value (when caused by disconnection), abnormality is judged, and abnormality information is carried out based on the judgment. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric rice cooker, and more particularly to an electric rice cooker that automatically diagnoses an abnormality of a heating unit and notifies an abnormality.
[0002]
[Prior art]
Generally, in the case of an electric rice cooker, as a heating means for heating the rice cooker, there is a main heating means (for example, an IH coil or a hot plate heater) which operates at the time of rice cooking, and sometimes also operates at the time of rice cooking. Auxiliary heating means (for example, a warming heater, a shoulder heater, or a lid heater).
[0003]
By the way, if a failure (for example, destruction of the control element) occurs in the circuit of the heating means, it can be protected by fusing the thermal fuse or the like (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP 2001-245786 A.
[0005]
[Problems to be solved by the invention]
However, in the case of the main heating means, it can be protected by blowing the thermal fuse.However, in the case of the auxiliary heating means, since the power is smaller than that of the main heating means, the thermal fuse may not be blown. is there. In particular, when an electric heater is used as the auxiliary heating means, even if the control element is destroyed, the circuit impedance is large, so that the temperature fuse does not blow and the energized state may be maintained. The condition may be degraded, and in some cases, the temperature may rise abnormally and the resin portion may be melted.
[0006]
The present invention has been made in view of the above points, and aims to provide a safer electric rice cooker by reliably detecting an abnormality of a heating unit and notifying the user of the abnormality. is there.
[0007]
[Means for Solving the Problems]
In the present invention, as a first means for solving the above problems, a rice cooker for storing rice, a heating means for heating the rice cooker, a temperature detecting means for detecting a temperature of the rice cooker, In an electric rice cooker provided with a control circuit for controlling a heating means and the like, a current detection means for detecting an input current to the heating means, and a step in which the rice cooker is started after power is turned on, in which the control circuit causes When the detection current detected by the current detection means when the heating means is turned on is equal to or less than a predetermined value, or when the detection current detected by the current detection means when the heating means is turned off by the control circuit is a predetermined value. In the above case, a judging means for judging an abnormality is provided, and a notifying means for giving an error notification when the judging means judges an abnormality.
[0008]
With the above-described configuration, when the heating circuit is turned on by the control circuit before the start of rice cooking after the power is turned on, the detection current detected by the current detection unit is equal to or less than a predetermined value (due to disconnection or the like). Case), or when the detection current detected by the current detection means when the heating means is turned off by the control circuit is equal to or greater than a predetermined value (due to a control element abnormality), an abnormality is determined, and based on the determination, an abnormality notification is made. Will be done. Therefore, any abnormal state of the heating means can be accurately detected.
[0009]
According to the present invention, as a second means for solving the above problems, in the electric rice cooker provided with the first means, the current detection means performs limiter control of an input current to the control circuit. In this case, the existing input current detecting means can be used as a current detecting means for automatic diagnosis, which is advantageous in cost.
[0010]
According to the invention of the present application, as a third means for solving the above problem, in an electric rice cooker provided with the above first or second means, the control circuit turns on / off the heating means by power. In this case, the automatic diagnosis can be performed every time the power is turned on, and the occurrence of an abnormality can be detected more accurately.
[0011]
According to the present invention, as a fourth means for solving the above-mentioned problem, in the electric rice cooker provided with the first, second, or third means, when the determination means determines that there is an abnormality, In addition, it is possible to prohibit the rice cooking by the rice cooking start operation. In such a case, the rice cooking in the abnormal state is prohibited, and the safety can be further secured.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0013]
The electric rice cooker has a double-structured rice cooker main body 1 configured to accommodate a rice cooker 3 for rice cooking therein and having a space portion 4, and an upper opening of the rice cooker main body 1 can be opened and closed freely. And a cover 2 for covering.
[0014]
The rice cooker main body 1 has an outer case 5 made of an integrally molded synthetic resin having a body portion 5a serving as an outer wall and a bottom portion 5b serving as a bottom wall, and a bottomed cylindrical shape made of a synthetic resin serving as an inner peripheral wall. It is constituted by a protective frame 6 and a synthetic resin shoulder member 7 for joining the upper end of the protective frame 6 and the upper end of the outer case 5, and is surrounded by the outer case 5, the protective frame 6 and the shoulder member 7. Thus, the space 4 is formed. Note that the rice cooker 3 is housed in the protective frame 6 so as to be removable.
[0015]
At the center of the bottom of the protection frame 6, a sensor hole 9 for receiving a center sensor 8 serving as a temperature detecting means for detecting the temperature of the rice cooker is formed.
[0016]
An annular electromagnetic induction coil (hereinafter, referred to as an IH coil) 10 acting as a heating means at the time of cooking rice so as to surround the sensor hole 9 is a bottom surface of the protective frame 6 and a curved portion extending from the bottom surface to a side peripheral surface. It is arranged corresponding to. The IH coil 10 generates an alternating magnetic field (in other words, an electromagnetic wave), generates an induced eddy current in the rice cooker 3 by electromagnetic induction of the alternating magnetic field, and utilizes the resistance heat of the induced eddy current. And heat it. The rice cooker 3 is made of a material (for example, a magnetic material) that can generate an induced eddy current by the IH coil 10.
[0017]
The IH coil 10 is sandwiched between a coil die 11 fixed to the bottom surface of the protection frame 6 and the bottom surface of the protection frame 6. Reference numeral 12 denotes a ferrite core, which has a function of blocking so that the magnetism of the IH coil 10 does not affect the underlying devices.
[0018]
A center sensor 8 is provided in the sensor hole 9 so as to contact the bottom of the rice cooker 3. Further, on the side peripheral surface of the protective frame 6, a heat retaining heater 13 which acts as a heating means at the time of keeping the temperature is attached.
[0019]
On the bottom of the rice cooker main body 1 (that is, the bottom 5b of the outer case 5), cooling air is supplied to electronic components such as a power transistor and a rectifying diode bridge (not shown) for controlling the energization of the IH coil 10. An electronic component cooling fan 14 for pumping is provided. An air inlet 15 is formed on the bottom wall of the rice cooker main body 1 (specifically, on the bottom 5 b of the outer case 5) so as to face the electronic component cooling fan 14.
[0020]
On the other hand, the lid 2 is composed of a synthetic resin upper plate 16 forming an outer surface and a synthetic resin lower plate 17 forming an inner surface, and a space surrounded by the upper and lower plates 16, 17. The part 18 is provided with a heat insulating material 19.
[0021]
The lid 2 is rotatably and detachably attached to the rice cooker main body 1 via a hinge unit 20 formed on one side of the shoulder member 7.
[0022]
At the center of the lid 2, there is formed a tubular portion 21 vertically suspended from the upper plate 16, and inside the tubular portion 21, a steam for discharging steam generated during rice cooking to the outside is provided. A steam cap 23 having a steam discharge passage 22 is detachably attached. In the steam cap 23, a ball valve 24 acting as a pressure regulating valve is provided. At the lower end of the steam cap 23, a heat radiating plate 25 made of a good heat conductor (for example, aluminum alloy) for sealing the opening 3a of the rice cooker 3 when the lid 2 is closed is attached. Reference numeral 26 denotes a steam inlet to the steam cap 23, 27 denotes a steam outlet from the steam cap 24, 28 denotes a steam port formed on the heat sink 25, 29 denotes a portion between the periphery of the heat sink 25 and the opening 3 a of the rice cooker 3. A seal packing 30 seals the gap between the heat radiating plate 25 and the lid lower plate 17.
[0023]
The shoulder member 7 is provided with a shoulder heater 31. The outer peripheral edge of the heat radiating plate 25 is pressed against the shoulder heater 31 when the lid 2 is closed. Is to be heated by the heat conduction. The shoulder heater 31 includes a heater ring 32 having an inverted U-shaped cross section and a heating element 33 disposed inside the heater ring 32.
[0024]
The lid 2 is located inside the heat sink 25 and faces inward from the opening 3a of the rice cooker 3 with a space interposed between the heat sink 25 and the heat sink 25. In addition, an inner lid 34 made of a good thermal conductor is provided, the outer periphery of which is close to the inner peripheral surface of the rice cooker 3. The inner lid 34 is attached to a seal packing 36 which is removably fitted to a support shaft 35 projecting downward from the center of the steam cap 23.
[0025]
A blower fan 37 is arranged in a space 4 in a side part (for example, the hinge unit 20 side) in the rice cooker main body 1 in a state attached to the shoulder member 7. The blower fan 37 is a centrifugal fan having a scroll type fan casing.
[0026]
A duct 38 is connected to a discharge port 37 a of the blower fan 37, and an upper end of the duct 38 faces an inlet 39 a of an annular passage 39 formed in the shoulder member 7. The shoulder member 7 has a plurality of communication ports 40 communicating the annular passage 39 with an upper portion of an annular gap C formed between the rice cooker 3 and the protection frame 6. . That is, the air from the air blowing fan 37 is supplied to the upper part of the gap C through the duct 38, the annular passage 39, and the communication port 40. Reference numeral 41 denotes an air intake formed in the lower part of the body 5a of the outer case 5.
[0027]
In the space 4 on the side opposite to the hinge of the rice cooker main body 1 (that is, the side on which the lock mechanism 42 for locking the lid 2 is provided), power is supplied to the IH coil 10, the heat retention heater 13, the shoulder heater 31, and the like. While a control board 43 in which a control unit for controlling is incorporated is provided, on the other side of the shoulder member 7 on the side opposite to the hinge (that is, the side on which the lock mechanism 42 for locking the lid 2 is provided), An operation panel unit 44 including operation switches (eg, a rice cooker switch, a reservation switch, etc.) and a liquid crystal display device serving as a display device is provided.
[0028]
Although not shown, the operation panel section 44 is provided with various keys and a liquid crystal display device for executing rice cooking or heat retention.
[0029]
Next, an electric configuration of the electric rice cooker according to the present embodiment will be described based on an electric circuit diagram shown in FIG. Parts corresponding to the respective parts shown in FIG. 1 are denoted by the same reference numerals.
[0030]
Electric power from the commercial AC power supply 45 is supplied to the IH coil 10 via the rectifier circuit 46, and is also supplied to the heat retention heater 13 and the shoulder heater 31. Reference numeral 47 denotes a choke coil, reference numeral 48 denotes a smoothing capacitor, reference numeral 49 denotes a resonance capacitor, and reference numerals 50 and 51 denote phototriacs for driving the heater.
[0031]
The IH coil 10 is supplied with a control signal from a power transistor 54 that is ON / OFF controlled by a command through a IGBT drive circuit 53 from a microcomputer unit (hereinafter abbreviated as a microcomputer) 52 acting as a control circuit. It has become.
[0032]
The microcomputer 50 is supposed to be supplied with an input current input through a current transformer 55 via a current detector 56 acting as a current detecting means, and controls the power transistor 54 according to a predetermined program. This controls the energization of the IH coil 10 and outputs a control signal to the notification means 57 such as a buzzer. This energization control is performed based on an output signal from a thermistor incorporated in the center sensor 8 (see FIG. 1). Reference numeral 58 denotes a memory. The current detector 56 is constituted by existing input current detecting means provided for performing limiter control of the input current to the microcomputer 52. In this case, the existing input current detecting means can be used as the current detector 56 for automatic diagnosis, which is advantageous in cost.
[0033]
Next, automatic diagnosis control in the electric rice cooker according to the present embodiment will be described in detail with reference to flowcharts shown in FIGS.
(I) Automatic diagnostic control I
The automatic diagnosis control I will be described with reference to the flowchart shown in FIG.
[0034]
In step S1, the power is turned on. In step S2, the IH coil 10, which is the main heating means, is turned on by a command from the microcomputer 52. When the detected current I is input to the microcomputer 52 in step S3, the detected current I is detected in step S4. Is determined within a predetermined current range. When a negative determination is made here (that is, when it is determined that I <Is (Is; set value)), the process proceeds to step S5, and the IH coil 10 is abnormal (that is, a current normally flows through the IH coil 10). Is not determined), and in step S6, the notification unit 57 (for example, a buzzer) notifies the abnormality.
[0035]
On the other hand, if an affirmative determination is made in step S4 (that is, if it is determined that I ≧ Is), the process proceeds to step S7, where the IH coil 10 is turned off by a command from the microcomputer 52, and in step S8, the IH coil 10 is turned off. The shoulder heater 31, which is the auxiliary heating means, is turned on by the command of (1), and it is determined in step S9 whether or not the detected current I is within a predetermined current range.
[0036]
When a negative determination is made here (that is, when it is determined that I <Is (Is; set value)), the process proceeds to step S10, and the shoulder heater 31 is abnormal (that is, a current normally flows through the shoulder heater 31). Is not determined), and in step S11, the notification unit 57 (for example, a buzzer) notifies the abnormality.
[0037]
On the other hand, if an affirmative determination is made in step S9 (that is, if it is determined that I ≧ Is), the process proceeds to step S12, in which the shoulder heater 31 is turned off by a command from the microcomputer 52, and in step S13, the shoulder heater 31 is turned off. In response to this command, the heat retention heater 13 serving as the auxiliary heating means is turned on, and it is determined in step S14 whether the detected current I is within a predetermined current range.
[0038]
When a negative determination is made here (that is, when it is determined that I <Is (Is; set value)), the process proceeds to step S15, and the heat retention heater 13 is abnormal (that is, a current normally flows through the heat retention heater 13). Is not determined), and in step S16, the notification unit 57 (for example, a buzzer) notifies the abnormality.
[0039]
When the abnormality is notified in step S6, step S11, and step S16, the rice cooking by the rice cooking start operation is prohibited in step S17 (that is, even if the rice cooking key is turned on, the rice cooking is prohibited). Is terminated.
[0040]
On the other hand, if an affirmative determination is made in step S14 (that is, if it is determined that I ≧ Is), the process proceeds to step S18, where the heat retaining heater 13 is turned off by a command from the microcomputer 52, and a normal process is performed in step S19. (For example, rice cooking), and then the control ends.
[0041]
As described above, the microcomputer 52 sequentially turns on the IH coil 10, the shoulder heater 31, and the heat retaining heater 13 by the microcomputer 52 before the rice cooking starts after the power is turned on, and the current is detected by the current detector 54 at that time. If the detected current I is equal to or smaller than the predetermined value Is (due to a disconnection or the like), it is determined that there is an abnormality, and an abnormality is notified based on the determination. Therefore, any abnormal state of the heating means can be accurately detected. In addition, when the abnormality is notified, the rice cooking by the rice cooking start operation is prohibited (that is, even if the rice cooking key is turned on, the rice cooking is prohibited), so that the safety is further improved. Will be done.
[0042]
(II) Automatic diagnostic control II
The automatic diagnosis control II will be described with reference to the flowchart shown in FIG.
[0043]
In step S1, it is determined whether or not the IH coil 10, which is the main heating unit, the warming heater 13, and the shoulder heater 31, which are the auxiliary heating units, are turned off in accordance with a command from the microcomputer 52. In step S2, the detection current I from the current detector 54 is input to the microcomputer 52, and it is determined in step S3 whether the input current I is within the normal range.
[0044]
If a negative determination is made here (that is, if it is determined that Is ₁ ≦ I (Is ₁ ; lower limit set value)), it is determined in step S4 whether the power at that time is equal to or less than 100 W. If an affirmative determination is made, the process proceeds to step S5, in which the heat retention heater 13 and / or the shoulder heater 31 serving as the auxiliary heating means (ie, the auxiliary heater) is abnormal (that is, the phototriac controlling these heaters 13, 31). 50 and 51 are determined to be abnormal), and an abnormality notification I (for example, a long-period sound of a buzzer) is performed by the notification unit 57 in step S6.
[0045]
On the other hand, if a negative determination is made in step S4, it is determined in step S7 that the IH coil 10, which is the main heating means, is abnormal (that is, the power transistor 54 and the IGBT drive circuit 53 that control the IH coil 10 are abnormal). In step S8, the abnormality is notified by the notification means 57 (for example, a short-period sound of a buzzer).
[0046]
When the abnormality is notified in step S6 and step S8, rice cooking by the rice cooking start operation is prohibited (that is, even if the rice cooking key is turned on, rice cooking is prohibited), and then the control is terminated.
[0047]
If a negative determination is made in step S1 and an affirmative determination is made in step S3, a normal process (for example, rice cooking) is executed in step S10, and then the control ends.
[0048]
As described above, when the microcomputer 52 turns off the IH coil 10, the shoulder heater 31, and the heat retaining heater 13 which are the heating means by the microcomputer 52 before starting the rice cooking, the current is detected by the current detector 54. Although the detected current I is determined to be abnormal if the upper limit set value is ₁ or more, insulation heater 13 and shoulder heater 31 is an auxiliary heating means when the power at that time is considerable less 100W is determined to be abnormal, when the If the electric power exceeds 100 W, the IH coil 10, which is the main heating means, is determined to be abnormal, and two types of abnormality notification are made based on each determination. Therefore, any abnormal state of the heating means can be accurately detected. In addition, when the abnormality is notified, the rice cooking by the rice cooking start operation is prohibited (that is, even if the rice cooking key is turned on, the rice cooking is prohibited), so that the safety is further improved. Will be done.
[0049]
As the notification means, a voice, a character display, or the like may be employed in addition to the buzzer.
[0050]
The automatic diagnosis may be performed at a predetermined time during the warming process (for example, at the time of heating OFF, at the time of forcible OFF, or at the time of independent operation), may be performed at each operation of detecting the absence of a pot, and the rice cooker key may be turned on. It may be performed for each operation.
[0051]
In the above embodiment, the IH coil is used as the main heating means, but an electric heater or the like may be used as the main heating means.
[0052]
【The invention's effect】
According to the first means of the present invention, control of a rice cooker for storing rice, heating means for heating the rice cooker, temperature detecting means for detecting the temperature of the rice cooker, and the heating means and the like is provided. An electric rice cooker provided with a control circuit for performing the operation, when the heating means is turned on by the control circuit until the rice cooking is started after the power is turned on, and the detection current detected by the current detection means is equal to or less than a predetermined value ( If the detected current detected by the current detecting means when the heating means is turned off by the control circuit is greater than or equal to a predetermined value (due to a control element abnormality), it is determined to be abnormal, and based on the determination. Since the abnormality notification is performed, any abnormal state of the heating means can be accurately detected, and there is an effect that the safety is greatly improved.
[0053]
As in the second means of the present invention, in the electric rice cooker provided with the first means, the current detection means is provided with an existing input current provided to perform limiter control of the input current to the control circuit. It can also be constituted by a detecting means. In such a case, the existing input current detecting means can be used as a current detecting means for automatic diagnosis, which is advantageous in cost.
[0054]
As in the third means of the present invention, in the electric rice cooker provided with the first or second means, the control circuit may perform ON / OFF control of the heating means every time power is turned on. In such a case, automatic diagnosis can be performed each time the power is turned on, and the occurrence of an abnormality can be detected more accurately.
[0055]
As in the fourth means of the present invention, in the electric rice cooker provided with the first, second, or third means, when the determination means determines that there is an abnormality, the rice cooking by the rice cooking start operation is prohibited. In such a case, rice cooking in an abnormal state is prohibited, so that safety can be further secured.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an electric rice cooker according to an embodiment of the present invention.
FIG. 2 is a connection diagram of a control circuit unit in the electric rice cooker according to the embodiment of the present invention.
FIG. 3 is a flowchart of automatic diagnosis control I in the electric rice cooker according to the embodiment of the present invention.
FIG. 4 is a flowchart of automatic diagnosis control II in the electric rice cooker according to the embodiment of the present invention.
[Explanation of symbols]
3 is a rice cooker, 8 is a temperature detecting means (temperature sensor), 10 is a main heating means (IH coil), 13 is an auxiliary heating means (insulation heater), 31 is an auxiliary heating means (shoulder heater), 50 and 51 are photo Triac, 52 is a control circuit (microcomputer), 56 is current detection means (current detector), and 57 is notification means.

Claims (4)

A rice cooker for storing rice, a heating unit for heating the rice cooker, a temperature detection unit for detecting the temperature of the rice cooker, and an electric rice cooker including a control circuit for controlling the heating unit and the like. A current detecting means for detecting an input current to the heating means; and a current detection means for detecting that the heating means is turned on by the control circuit during a period from power-on until rice cooking is started. Determining means for determining an abnormality when the detected current is equal to or less than a predetermined value, or when the detected current detected by the current detecting means when the heating means is turned off by the control circuit is equal to or more than a predetermined value; An electric rice cooker further provided with a notifying means for notifying an abnormality when it is determined that the abnormality is abnormal. 2. The electric rice cooker according to claim 1, wherein said current detection means is constituted by an existing input current detection means provided for performing limiter control of an input current to said control circuit. The electric rice cooker according to any one of claims 1 and 2, wherein ON / OFF control of the heating means by the control circuit is performed every time power is turned on. The electric rice cooker according to any one of claims 1 to 3, wherein rice cooking by the rice cooking start operation is prohibited when the determination means determines that the rice cooker is abnormal.

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