JP3175670B2 - Electric 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 electric rice cooker, and more particularly to an electric rice cooker having a function of detecting the presence or absence of an inner pot.

[0002]

2. Description of the Related Art In general, in an electric rice cooker, an inner pot containing rice and water is housed in a rice cooker body, and the inner pot is heated by a heating means (for example, an electromagnetic induction coil) to cook rice. Is to run.

In the case of the electric rice cooker having the above-mentioned configuration, rice cannot be cooked even if the electromagnetic induction coil is operated in a state where the inner pot is not stored in the rice cooker main body. When the container is stored, if the stored container is a magnetic material, the container generates heat due to electromagnetic induction and the rice cooker body may be melted by the heat, so the presence or absence of the inner pot is detected, and the inner pot is detected. The heating means can be operated only when stored in the rice cooker main body.

As a method of detecting the inner pot, an inner pot detection switch (for example, a combination of a magnet and a reed switch) built in the center sensor is turned on / off.
A method of detecting the presence or absence of an inner pot by F has been conventionally used.

[0005]

However, in the case of the above prior art, an inner pot detection switch (for example, a combination of a magnet and a reed switch) is required, which has been a bottleneck in reducing costs. .

[0006] The present invention has been made in view of the above points, and an object of the present invention is to make it possible to reliably detect an inner pot at low cost.

[0007]

According to the basic structure of the present invention (the first aspect of the present invention), as means for solving the above-mentioned problems, electromagnetic induction for generating an induced current in an inner pot containing rice and water is provided. Detecting means for detecting a continuous energizing state of the electromagnetic induction coil in an electric rice cooker having a coil ;
Means detects that the electromagnetic induction coil is continuously energized.
Power supply to the electromagnetic induction coil was stopped for a predetermined time
Energization control means for re-energizing after , and
Voltage detection means for detecting a feedback voltage generated at the time of energization , and determination means for determining the presence or absence of the inner pot based on a change in the feedback voltage detected by the voltage detection means at the time of re-energization by the energization control means are additionally provided. ing.

[0008] With the above configuration, the electromagnetic induction coil is in a continuous energized state and is controlled by the energization control means.
If the inner pot is set in a normal state at the beginning of re-energization after the power supply is stopped for a predetermined time, the feedback voltage detected by the voltage detecting means is set to a set value (that is, the inner pot is set in a normal state). Is equal to the feedback voltage generated when the inner pot is set, that is, whether the feedback voltage is different from the set value (that is, the feedback voltage generated when the inner pot is normally set) (in other words, whether the feedback voltage is different from the set value).
Then, the presence or absence of the inner pot can be determined by detecting the change during re-energization . Therefore, the presence or absence of an inner pot can be detected at low cost without using a mechanical switch such as an inner pot detection switch.

[0009] When an alarming means is provided for generating an alarm when the judging means judges that there is no inner pot as in the second aspect of the present invention, the user can be informed of the absence of the inner pot by an alarm. In addition, accidents such as heating without the inner pan can be prevented.

[0010] As in the invention of claim 3, during the cooking of rice, when it is determined by the determination means that there is no inner pot , power is supplied.
When the initial state returning means for returning to the stop state is provided, when the inner pan is not stored, the state is returned to the power supply stop state, and an accident such as heating without the inner pan can be prevented.

[0011]

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

First Embodiment (Corresponding to Claims 1 to 3) FIGS. 1 to 4 show an electric rice cooker according to a first embodiment of the present invention.

As shown in FIG. 1, this electric rice cooker is constructed so that an inner pot 3 for rice cooking can be set therein, and has a double-structured container body 1 having a space portion 4; And a cover 2 for covering the upper opening of the cover 1 so as to be openable and closable.

The container body 1 has a body 5a serving as an outer wall.
And an outer case 5 made of a synthetic resin (e.g., polypropylene) having an upper wall and a shoulder 5b serving as an upper wall, and a synthetic resin (e.g., an upper end joined to the inner peripheral edge of the shoulder 5b). It is composed of a bottomed cylindrical inner case 6 made of polypropylene) and a dish-shaped bottom member 7 made of a synthetic resin (for example, made of polypropylene) whose upper end is coupled to the lower end of the body 5a of the outer case 5. The space 4 is surrounded by the outer case 5, the inner case 6, and the bottom member 7.
Are formed. Note that the inner pan 3 is set in the inner case 6 so as to be removable.

In the center of the bottom surface of the inner case 6, there is formed a sensor hole 9 for facing a center sensor 8 acting as a temperature detecting means. The sensor hole 9 acts as a heating means so as to surround the sensor hole 9. An annular electromagnetic induction coil (hereinafter referred to as a work coil) 10 is provided in the inner case 6.
And a curved portion between the bottom surface and the side peripheral surface. The work coil 10 generates an alternating magnetic field, and the inner pot 3 is generated by electromagnetic induction of the alternating magnetic field.
An eddy current, which is an induced current, is generated, and heating is performed using the resistance heat of the eddy current. In addition, inner pot 3
Is made of a material (for example, a magnetic material) capable of generating an eddy current by the work coil 10.

The work coil 10 is mounted on the inner case 6.
Between the work coil die 12 fixed to the bottom surface of the inner case 6 by screws 11 and the bottom surface of the inner case 6. Reference numeral 12a denotes a ferrite core, which acts to block so that the magnetism generated by the work coil 10 does not affect the underlying devices.

A center sensor 8 is provided in the sensor hole 9 so as to be in contact with the bottom of the inner pot 3. A heater 13 for keeping heat is attached to a side peripheral surface of the inner case 6. Further, a cylindrical partition wall 14 is suspended from the lower surface of the outer case shoulder 5b, and a heat insulating material 15 is disposed between the partition wall 14 and the inner case 6.

Below the work coil die 12, a substrate 16 is supported, and a cooling fan 17 is also provided.
The cooling fan 17 sends cooling air to a power transistor and a rectifying diode bridge (not shown) disposed on the substrate 16 in order to control the energization of the work coil 10. And an axial impeller 19 that is driven to rotate by the fan motor 18. The bottom wall of the container body 1 (specifically,
On the bottom surface of the bottom member 7), a cooling air inlet 20 is formed to face the cooling fan 17.

On the other hand, the lid 2 is composed of an upper plate 21 made of synthetic resin (for example, made of polypropylene) constituting the outer surface and an annular lower plate made of synthetic resin (made of, for example, polypropylene) constituting the inner peripheral surface. 22 and a metal radiator plate 23 attached to the inner peripheral edge of the lower plate 22. A space 25 surrounded by the upper and lower plates 21 and 22 and the radiator plate 23 includes a heat insulating material 24. Are arranged.

The lid 2 is provided with a shoulder 5b of the outer case 5.
Is rotatably and detachably attached to one side via a hinge pin 26.

At the center of the lid 2, there is formed a tubular portion 27 which is suspended from the upper plate 21, and the inside of the tubular portion 27 discharges steam generated during rice cooking to the outside. And a steam discharge passage 28. A pressure regulating cylinder 30 for adjusting the internal pressure of the inner pot 3 during rice cooking is attached to the lower end of the cylindrical portion 27 via a seal packing 29.

The radiator plate 23 is provided with the steam discharge passage 2.
8, a hole 31 corresponding to the lower end is formed.
Is connected to and supported by the seal packing 29. The outer peripheral edge of the heat radiating plate 23 is connected to the inner peripheral edge of the lower plate 22 via a seal packing 32. When the lid 2 is closed, the seal packing 32 is pressed against the upper rim of the inner pot 3 to maintain airtightness.

On the upper surface of the heat sink 23, the heat sink 23
A lid heater 33 for preventing dew formation and growth of oneva by heating the fin is provided.

In the space 4 on the front side of the container body 1 (ie, on the side where the lock mechanism 34 for locking the lid 2 is provided), the work coil 10, the heater 13 and the lid heater 33 are provided. A control board 36 in which a control unit for controlling power supply is incorporated is provided.
Are provided with various switches (for example, a rice cooker switch, a reservation switch, a heat insulation switch, etc.) and a liquid crystal display device 37. Reference numeral 35 denotes a board cover for fixing the control board 36 and shutting off heat from the heater 13, and 38 denotes an operation panel provided on the front face of the switch board 36 and the liquid crystal display device 37.

As shown in FIG. 2, the operation panel section 38 includes a rice cooker switch 39, a warming switch 40, a reservation switch 41, a menu switch 42, and a reheating switch 4.
3. A liquid crystal display window 44 and the like are provided.

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 those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

The electric power from the commercial AC power supply 45 is supplied to the work coil 10 via the temperature fuse 46 and the rectifying circuit 47 which detect and abnormally heat the inner pot 3 and blow it. Reference numeral 48 denotes a smoothing capacitor, and 49 denotes a resonance capacitor.

The work coil 10 is supplied with a control signal from a power transistor 52 that is turned on / off by a command from a microcomputer unit 50 via an IGBT drive circuit 51.

The microcomputer unit 50
Is a power transistor 51 according to a predetermined program.
, Thereby controlling the energization of the work coil 10. This energization control is performed by a thermistor 53 built in the center sensor 8 from the temperature sensor detection circuit 5.
4 based on the output signal output.

The microcomputer unit 50 receives an output signal from a voltage detection circuit 55 serving as voltage detection means for detecting a feedback voltage V when the work coil 10 is energized. ing.

Further, the microcomputer unit 50 functions as heating control means for controlling the work coil 10 with predetermined rice cooking characteristics based on the temperature detected by the center sensor 8 (specifically, the thermistor 53); A detection for detecting the continuous energization state of the work coil 10
The function as the informing means and the work co
When the continuous energization state of the file 10 is detected, the work coil
During a predetermined time the power supply to the Le 10 (e.g., 01-3 second) reenergize by the energization control means and functions as a current control means for re-energizing after stopping, the detected feedback voltage by the voltage detection circuit 55 and functions as a determination means for determining whether said pot by a change in time, the energization stop when it is determined that no inner bowl by said judging means during cooking
It has a function as an initial state return unit for returning to the stop state. Here, the energization and the stopped state, like in which the power is turned OFF
Means state . Reference numeral 56 denotes an alarm buzzer that operates as an alarm unit that operates when it is determined that the inner pot 3 is not present.

Next, the inner pot detection control in the electric rice cooker having the above configuration will be described in detail with reference to a flowchart shown in FIG.

The presence or absence of an output of the work coil 10 in step S ₁ (i.e., whether the power is turned on) is determined, wherein if the determination is positive, the presence or absence of the detection of the feedback voltage V in step S ₂ determined Is done. The detection of the feedback voltage V is performed based on the presence or absence of a signal from the voltage detection circuit 55. If a positive result in this case, the induced current is generated in the inner bowl 3 it indicates (i.e., the inner pot 3 is housed and rice cooker body 1), to step S ₁ The process returns, and the presence or absence of output to the work coil 10 is monitored. In the case where a negative determination is made in step S _1, the process returns to the start, to monitor the presence or absence of an output of the work coil 10.

When a negative determination is made in step S _2, whether the inner pot 3 is stored in the rice cooker main body 1 or not is determined.
Or the change of the feedback voltage V by the continuous energization of the work coil 10 is shown that can not be detected, the process proceeds to step S _3, the work coil 10 16/1
(In other words, continuously being energized) is energized by 6 the duty ratio of the whether is determined, wherein the determination is affirmative, the process proceeds to step S _4, the duty ratio of the energization of the work coil 10 1/16 (i.e., 1 second) after stopping only returns to step S _1. The reason for this is that the change in the feedback voltage V can be detected only at the beginning of energization of the work coil 10, and cannot be detected when the work coil 10 is in the continuous energization state.

On the other hand, if a negative determination is made in step S ₃ in (i.e., not a continuous energization, if the at least one second is determined to be de-energized), negative (i.e. in step S _2, the feedback It is determined that the voltage V has not been detected), indicating that the inner pot 3 is not housed in the rice cooker body 1,
It is determined that there is no inner pot.

[0036] Next, "the inner pot no" in the step S ₅
Is determined 16 times. This determination is performed to confirm that the determination of “no inner pot” is not an erroneous determination due to disturbance or the like.

[0037] When an affirmative determination is made in step S _5, the process proceeds to step S _6, the control is the initial state (i.e., through
(Power stop state) . Now an affirmative determination is made, the process proceeds to step S _7, the alarm buzzer 56
The actuates after warning "no inner bowl" to the user, the initial state (i.e., de-energized state) in step S ₈ are.

[0038] When a negative determination is made in step S _6, the process proceeds to step S _9, a determination is made of whether or not the thermal insulation, wherein the determination is affirmative, the process proceeds to step S _10, the count of the incubated elapsed time After resetting, step S
_Proceeding to ₈ , the initial state (that is, the power supply stop state) is set.

[0039] When a negative determination is made in step S _9, the process proceeds to step S _11, a determination is made of whether or not the cooking, wherein when an affirmative determination is made, the process proceeds to step S _8, the initial state ( That is, the power supply is stopped) . In addition,
When a negative determination is made in step S _11, the process proceeds to step S _12, after warning of "no inner bowl" to the user by actuating an alarm buzzer 56, the initial state in step S ₈ (i.e., de-energized state) It is said. Incidentally, also, "inner bowl without" the user by operating the warning buzzer 56 when the determination is positive at step S ₉ and step S ₁₁
May be warned.

As described above, according to the present embodiment,
At the beginning of re-energization after stopping the energization of the work coil 10,
Is present , a change occurs in the feedback voltage V. Therefore, the presence or absence of the inner pot 3 can be determined by detecting whether or not the feedback voltage V has changed . Therefore, the presence or absence of the inner pot 3 can be detected at low cost without using a mechanical switch such as an inner pot detection switch. In addition, the user can be notified by the alarm buzzer 56 that the inner pot 3 is not present, thereby preventing an accident such as heating without the inner pot. In addition, in a normal electric rice cooker, during the determination of the amount of cooked rice, 16/16
However, in the case of the present embodiment, the duty ratio is always 1/16: OFF,
Duty ratio 15/16: ON.

Second Embodiment (Corresponding to Claims 1 to 3) FIG. 5 shows a flowchart of inner pot detection control in an electric rice cooker according to a second embodiment of the present invention.

In this case, the feedback voltage V is detected, and the feedback voltage V is set to a predetermined set value V
₀ (for example, a feedback voltage generated when the inner pot 3 is normally set), and when the two are different from each other, objects other than the inner pot 3 are placed in the rice cooker main body 1. It is determined that either it is stored or the inner pot 3 is not set in a normal state (that is, a foreign object is present between the inner pot 3 and the rice cooker body 1: foreign rice cooking). It is supposed to.

Hereinafter, the inner pot detection control in the electric rice cooker according to the present embodiment will be described in detail with reference to a flowchart shown in FIG.

The presence or absence of an output of the work coil 10 in step S ₁ (i.e., whether the power is turned on) is determined, wherein if the determination is positive, the detection of the feedback voltage V is performed in step S _2, step S ₃ preset and the detected feedback voltage V in set value V ₀ (e.g., the feedback voltage generated when the normally Uchinabe 3 is set) compared with is made. The detection of the feedback voltage V is performed by the voltage detection circuit 5.
This is done by a change in the signal from 5. Here, when it is determined that V = V ₀ , it indicates that the inner pot 3 is housed in the rice cooker main body 1 in a normal state, and the process returns to step S ₁ and returns to the work coil 10. Monitor for the presence of output. In the case where a negative determination is made in step S _1, the process returns to the start, to monitor the presence or absence of an output of the work coil 10.

The negative determination is made in step S ₃ (ie, V
If it is determined to be ≠ V ₀ ), whether the inner pot 3 is stored, other equipment is stored, or the inner pot 3 is not stored in the rice cooker body 1 in a normal state. or it indicates that the sequential energization of the work coil 10 is either not able to detect the feedback voltage V changes, the process proceeds to step S _4, the work coil 10 is 16 /
(In other words, continuously it is energized) and has been energized by the 16 duty ratio of the whether is determined, wherein the determination is affirmative, the process proceeds to step S _5, the duty ratio energization of the work coil 10 1/16 (i.e., 1 second) after stopping only returns to step S _1. The reason for this is that the change in the feedback voltage V can be detected only at the beginning of energization of the work coil 10,
This cannot be performed when is in a continuous energized state.

On the other hand, if a negative determination is made in step S ₄ (that is, if it is determined that the energization has been stopped for at least one second instead of continuous energization), whether the inner pot 3 has been stored is determined. Since it indicates that other objects are stored or the inner pot 3 is not stored in the rice cooker body 1 in a normal state, it is determined that “the inner pot is not present” or “foreign rice cooking”. You.

Next, "without the inner pot" in the step S ₆
Alternatively, it is determined whether or not the determination of “foreign rice cooking” has been made 16 times. This determination is performed to confirm that the determination of “no inner pot” or “foreign rice cooking” is not an erroneous determination caused by disturbance or the like.

[0048] When a positive determination is made in step S _6, the process proceeds to step S _7, the control is the initial state (i.e., through
(Power stop state) . Now an affirmative determination is made, the process proceeds to step S _8, the alarm buzzer 56
The actuates after warning "no inner bowl" or "foreign substances cooking" to the user, the initial state (immediately in step S ₉
That is, the power supply is stopped) .

[0049] When a negative determination is made in step S _7, the process proceeds to step S _10, a determination is made of whether or not the thermal insulation, wherein the determination is affirmative, the process proceeds to step S _11, the count of the incubated elapsed time After resetting, step S
_Proceeding to ₉ , the initial state (that is, the power supply stop state) is set.

[0050] When a negative determination is made in step S _10, the process proceeds to step S _12, a determination is made of whether or not the cooking, wherein when an affirmative determination is made, the process proceeds to step S _9, the initial state ( That is, the power supply is stopped) . In addition,
When a negative determination is made in step S _12, the process proceeds to step S _13, after warning of "no inner bowl" or "foreign substances cooking" to the user by actuating an alarm buzzer 56, the initial state in step S ₉ (i.e. , The power supply is stopped) . Even when the determination is positive at step S ₁₀ and step S _12, may be to operate the warning buzzer 56 warns the "no inner bowl" or "foreign substances cooking" to the user.

As described above, according to the present embodiment,
At the beginning of re-energization after stopping the energization of the work coil 10,
Since the feedback voltage V is equal to the set value V ₀ is if it is set in a normal state, by comparing the set value V ₀ and the feedback voltage V, set the inner pot 3 is normal state It is possible to determine whether or not it has been performed. Therefore, the presence or absence of the inner pot 3 can be detected at low cost without using a mechanical switch such as an inner pot detection switch. In addition, the user can be notified by the alarm buzzer 56 that the inner pot 3 is not set in a normal state, and it is possible to prevent an accident such as heating without the inner pot or a state of cooking foreign objects. In addition, in a normal electric rice cooker, 16 /
It is energized at a duty ratio of 16,
In the case of the present embodiment, the duty ratio is always 1/16: OF
F, duty ratio 15/16: ON.

In each of the above embodiments, the power supply to the work coil is stopped for one second to detect the feedback voltage.
An appropriate number of seconds between 0.1 and 3 seconds can be used.

[0053]

According to the invention of the present application (the invention of claim 1),
In an electric rice cooker provided with an electromagnetic induction coil for generating an induction current in an inner pot containing rice and water, detection means for detecting a continuous energization state of the electromagnetic induction coil , and the detection means
The continuous conduction state of the electromagnetic induction coil was detected by
After stopping the power supply to the electromagnetic induction coil for a predetermined time,
Energizing control means for energizing, and energizing the electromagnetic induction coil
Voltage detecting means for detecting a feedback voltage during generated, by attaching a determination means for determining whether said pot by the change at the time of re-energized by the energization control means of the detected feedback voltage by said voltage detecting means When the electromagnetic induction coil is in the continuous energized state and the energization control means
If the inner pot is set in a normal state or the inner pot is set in a normal state at the initial stage of re-energization after the power supply is stopped for a predetermined time , the feedback voltage is set to a preset value (ie, And the feedback voltage generated when the inner pot is set in a normal state), and by detecting a change in the feedback voltage, the presence or absence of the inner pot is determined. There is an excellent effect that the presence or absence of an inner pot can be detected at low cost without using a mechanical switch such as an inner pot detection switch.

As in the second aspect of the present invention, when an alarm means is provided for generating an alarm when the determination means determines that there is no inner pot, the user can be notified of the absence of the inner pot by an alarm. In addition, accidents such as heating without the inner pan can be prevented.

As in the third aspect of the present invention, when the determination means determines that there is no inner pot during the cooking of rice, power is supplied.
When the initial state returning means for returning to the stop state is provided, when the inner pan is not stored, the state is returned to the power supply stop state, and an accident such as heating without the inner pan can be prevented.

[Brief description of the drawings]

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

FIG. 2 is an enlarged front view of an operation panel unit in the electric rice cooker according to the first embodiment of the present invention.

FIG. 3 is a connection diagram of a control circuit unit in the electric rice cooker according to the first embodiment of the present invention.

FIG. 4 is a flowchart of inner pot detection control in the electric rice cooker according to the first embodiment of the present invention.

FIG. 5 is a flowchart of inner pot detection control in the electric rice cooker according to the second embodiment of the present invention.

[Explanation of symbols]

1 is a rice cooker container, 2 is a lid, 3 is an inner pot, 10 is a rice heating means (work coil), 50 is a microcomputer unit, 55 is a voltage detection circuit (voltage detection means), 56 is an alarm means (alarm buzzer) ).

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-115364 (JP, A) JP-A-4-371108 (JP, A) JP-A-5-253057 (JP, A) 54753 (JP, A) JP-A-8-317857 (JP, A) JP-A-8-191751 (JP, A) JP-A-1-313880 (JP, A) JP-A-51-228749 (JP, A) Patent 2684771 (JP, B2) JP 7-93906 (JP, B2) JP 61-31503 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) A47J 27/00

Claims (3)

(57) [Claims] 1. An electric rice cooker having an electromagnetic induction coil for generating an induction current in an inner pot containing rice and water,
Detecting means for detecting a continuous energizing state of the electromagnetic induction coil
And the continuous conduction state of the electromagnetic induction coil by the detecting means.
When power is supplied to the electromagnetic induction coil when a condition is detected,
Energizing control means for re-energizing after stopping between a voltage detecting means for detecting a feedback voltage generated upon energization of the electromagnetic induction coil, re-energized by the energization control means of the detected feedback voltage by said voltage detecting means Time
And a determination means for determining the presence or absence of the inner pot based on a change in the electric pot. 2. The electric rice cooker according to claim 1, further comprising alarm means for generating an alarm when the judging means judges that there is no inner pot. 3. An apparatus according to claim 1 , further comprising an initial state return means for returning to a power-off state when the determination means determines that there is no inner pot during the rice cooking . An electric rice cooker according to claim 1.