JP4013373B2 - Induction heating rice cooker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction heating type rice cooker.
[0002]
[Prior art]
Hereinafter, a conventional induction heating rice cooker will be described with reference to FIG. The rice cooker body 1 is provided with an inner pot 2 for storing rice and water. By energizing the heating coil 4 with a high-frequency current supplied by the inverter 3 to generate a high-frequency magnetic field, the inner pot is induction-heated to cook rice.
[0003]
[Problems to be solved by the invention]
Induction heating rice cooker with the above-mentioned conventional configuration is unnecessary because the inverter continues to operate when the inner pot is removed from the rice cooker body during inverter operation after installing the inner pot in the rice cooker body and turning on the rice cooking switch A high-frequency magnetic field may be generated.
[0004]
An object of the present invention is to stop the inverter and prevent unnecessary high-frequency magnetic fields from being generated when the inner pot is removed from the rice cooker body during inverter operation during rice cooking.
[0005]
[Means for Solving the Problems]
The present invention is intended to solve the conventional problems above, the input current detecting means for detecting a current supplied to the inverter, the on-time control means for controlling the ON time of the switching elements constituting the inverter, the at cooking When the inner pot is installed at the time of heat retention and the first threshold value that is less than the input current when the inner pot is installed with the ON time of the switching element as the control upper limit value and more than the input current when it is removed A second threshold value that is less than or equal to the input current at the operating point of the on-time of the switching element and greater than or equal to the input current at the on-time at the operating point when removed. detecting that the input current with reaching the upper control limit is detected by the input current detecting means at the time of cooking is less than the first threshold value If, also at least once the inverter when it is detected that during insulation is less year second threshold is made to stop.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The invention described in claim 1 can effectively suppress the generation of an unnecessary high-frequency magnetic field by comparing the input current of the inverter in a state where the pan is disposed and in a state where the pan is not disposed.
[0007]
【Example】
Examples of the present invention will be described below. FIG. 1 is a block diagram of the induction heating rice cooker of the present embodiment. The current supplied from the commercial power source 5 to the inverter 3 is detected by the input current detection means 6. In this embodiment, the input current detection means 6 is constituted by a circuit using a current transformer. It is converted into a high frequency current by the inverter 3 and supplied to the heating coil 4 to generate a high frequency magnetic field, and the inner pot 2 is induction heated to cook rice. In this embodiment, the inverter 3 has the circuit configuration shown in FIG. That is, the inverter is a one-stone voltage resonance type inverter composed of a rectifier 21, a filter 22, a resonance capacitor 23 and a switching element 24. The on-time of the switching element can be controlled to an arbitrary input power by controlling the on-time control means 7 by an input power control means (not shown). Here, the on-time is controlled so that the input current becomes a certain value to obtain a desired input current during cooking. Here, the relationship between the switching element ON time and the input current is shown in FIG. The pan removal detecting means 8 is realized by a microcomputer program (not shown). A flowchart of the pan removal detecting means is shown in FIG.
[0008]
Hereinafter, the operation of this embodiment will be described with reference to FIG. When the inner pot is installed in the rice cooker body, the point on the operation line when the inner pot is installed becomes the operating point, and the switching element ON time is changed to control the input current during cooking. When the inner pot is removed from the rice cooker body, it is considered that the inverter operates at the operating point on the operation line when the inner pot is removed. Between the operation line at the time of installing the inner pot and the operation line at the time of removing the inner pot, the operation line in the intermediate state (not shown), that is, the operation line in the state of removing the inner pot from the rice cooker body is between the rice cooker body and the inner pot. There are countless numbers depending on the distance. The first threshold value is equal to or less than the operating point at the time of installing the inner pot when the switching element ON time is set as the control upper limit value, that is, the input current at point D, and the inner pot when the ON time is set as the control upper limit value. Is set to be equal to or higher than the input current at the operating point when E is removed, that is, point E.
[0009]
At the time of rice cooking, an inner pan is installed in the rice cooker body and control is performed to obtain a desired rice cooking input current, so the inverter operates at the operating point A in the figure. Therefore, when the inner pot is removed, the operating point moves to point B as the inner pot is removed while controlling the input current during cooking. Since the point B is a control upper limit value of the switching element on-time, the on-time does not become longer than the point B, and the operating point is moved from the point B to the point C as the inner pan is removed. When point C is reached, the switching element ON time becomes the control upper limit value and becomes the first threshold value, so that the pan removal detecting means detects that the pan has been removed, and the inverter stops because the inverter stopping means is driven. . Therefore, when the induction heating type rice cooker of the present embodiment is used, if the pan is removed during the operation of the inverter, the inverter stops, and thus an unnecessary high frequency magnetic field is not generated.
[0010]
Further, a block configuration as shown in FIG. 5 is also conceivable. In other words, in addition to the above-described embodiment, the intermittent oscillation means 10, the soft start means 11, and the accessory detection means 12 are provided. The accessory detection means is realized by a microcomputer program (not shown). A flowchart of the accessory detection means is shown in FIG. When the inner pan is removed during the operation of the inverter during rice cooking, the same configuration and effect as in the previous embodiment are obtained. The input power can be reduced by driving the intermittent oscillation means to operate the inverter for 4 seconds out of 16 seconds and stopping it for 12 seconds in order to obtain the average input power required for heat retention during the heat insulation. Further, by driving the soft start means at the start of the inverter operation and gradually increasing the ON time of the switching element of the inverter from the control lower limit value, the switching element can be protected at the time of starting the inverter.
[0011]
The operation of this embodiment will be described with reference to FIG. When the inner pan is installed, if the inverter is operated during the heat insulation, the operating point is on the operating line when the inner pan is installed, and the operation starts from the point F by the operation of the soft start means. Since the operation point is moved to point G and control is performed to obtain a desired heat input current, the inverter operates at the point G in the figure. Eventually, the inverter is stopped by the operation of the intermittent oscillation means, and the operation from point F is repeated. If the inner pan is removed while the inverter is operating, that is, the point G is the operating point, the operating point shifts to the H point as the inner pan is removed while controlling the input current during the heat retention. When the inner pan is completely removed, the operation continues at the point H. After the inverter stops due to the operation of the intermittent oscillation means, the switching element on time operates the inverter again from the control lower limit value, but the inner pan is removed. Therefore, start from point I with the operating line on the operating line when removing the inner pan. The switching element ON time is lengthened from point I to point J on the inner pan removal operation line. When the point J is reached, the switching element ON time becomes a certain threshold value, and the input current is equal to or smaller than the second threshold value, so that the small object is detected by the small object detecting means and the inverter operation is stopped.
[0012]
Therefore, it is possible to stop the inverter when the inner pan is removed during the operation of the inverter, whether cooking rice or keeping warm, and an unnecessary high-frequency magnetic field is not generated.
[0013]
【The invention's effect】
As described above, according to the first aspect of the present invention, the inverter can be stopped when the pan is removed during the inverter operation . Moreover, even if it is not only during rice cooking but also during heat retention, when the pan is removed during the operation of the inverter, the inverter can be stopped and an induction heating rice cooker that does not generate an unnecessary high-frequency magnetic field can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of an induction heating rice cooker according to a first embodiment of the present invention. FIG. 2 is a circuit diagram of main components of the induction heating rice cooker. FIG. 3 is a circuit diagram of an induction heating rice cooker. (B) Relationship diagram between ON time of switching element and input current of induction heating type rice cooker of second embodiment of the present invention [FIG. 4] (a) Present invention FIG. 5 is a flowchart of the accessory detection means of the induction heating rice cooker of the second embodiment of the present invention. FIG. 5 is a flowchart of the accessory detection means of the induction heating rice cooker of the second embodiment of the present invention. Block diagram of an example induction heating rice cooker [Fig. 6] Block diagram of a conventional induction heating rice cooker [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rice cooker body 2 Inner pan 3 Inverter 4 Heating coil 6 Input current detection means 7 On-time control means 8 Pan removal detection means 9 Inverter stop means 10 Intermittent oscillation means 11 Soft start means 12 Small article detection means 24 Switching element

Claims (1)

Input current detection means for detecting the current supplied to the inverter, on-time control means for controlling the on-time of the switching elements constituting the inverter, and the on-time of the switching elements at the time of rice cooking as the control upper limit value A first threshold value that is less than or equal to the input current when the inner pan is installed and greater than the input current when the inner pan is removed, and the input current at the operating point of the on-time of the switching element when the inner pan is installed during heat insulation And a second threshold value that is equal to or higher than the input current during the on-time at the operating point when removed, and the on-time of the switching element reaches the control upper limit value and is detected by the input current detecting means it is the case where the input current is detected that the time rice is less than the first threshold value, and the second threshold year during insulation Induction heating cooker that at least once the inverter composed stopped when it is detected that is below.

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