JPH0675427B2 - Induction heating cooker - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an induction heating cooker that automatically performs appropriate heating control according to the amount of water in the object to be heated and the temperature at the start of heating and also detects boiling.

[Prior art]

FIG. 7 is a block diagram showing a conventional induction heating cooker disclosed in, for example, Japanese Patent Application Laid-Open No. 61-233988, in which reference numeral 1 is a top plate made of a non-conductive material. The pot 2 is placed on the top plate 1. 3 is water as an object to be heated housed in the pan 2 and 4 is a heating coil arranged in the lower part of the top plate 1. By generating a high frequency magnetic field,
Induction heat pan 2. 27 is a high-frequency power supply unit that supplies a high-frequency power supply to the heating coil 4, 28 is a vibration detection unit that detects the vibration of the top plate 1, 29 is a vibration detection unit that detects the vibration of the housing 32 that houses the heating coil 1, 30 Is a control circuit that controls the high-frequency power supply 27 in accordance with the vibration detection signals of the vibration detection units 28 and 29, and 31 is a display / notification unit that displays the control state by the control circuit 30 and issues various alarms. Next, the operation will be described. When a power switch (not shown) is turned on, the high-frequency power supply unit 27 starts a transmission operation to generate a high-frequency power supply and supply it to the heating coil 1. When a high frequency current flows through the heating coil 1, a high frequency magnetic field is generated. Here, since the pan 2 made of a conductive material is placed on the top plate 1 made of a non-conductive material, the pan 2 is a high frequency magnetic field generated from the heating coil 1. Will be fully and efficiently received. When the pan 2 receives a high frequency magnetic field, an eddy current flows in the pan 2 due to the inductive action. When the eddy current flows, a heat generating action occurs, so that the heat generated heats the pot 2 to heat the water 3 contained therein, which is the object to be heated, to boil. On the other hand, the vibration detectors 28 and 29 detect the vibration of the frame 32 housing the top plate 1 and the heating coil 1, and supply the vibration detection signal to the control circuit 30. The control circuit 30 analyzes the content of the vibration detection signal supplied from each vibration detection unit 28, 29,
A component below the transmission frequency in the high frequency power supply 27 is taken out, and when this component exceeds a preset reference value, it is determined that the water 3 contained in the pan 2 has boiled and the high frequency power supply 27 The output is reduced and the display / notification unit 31 is caused to perform the boiling display.

[Problems to be Solved by the Invention]

As described above, the conventional induction heating cooker may malfunction when vibration is applied from the outside, because it is judged as boiling when the vibration component level below the oscillation frequency in the high frequency power supply exceeds the set value. . In addition, in the above-mentioned configuration for detecting boiling by vibration detection, it is necessary to provide vibration detection units at two places, the top plate and the housing, and the vibration component level below the transmission frequency in the high frequency power source exceeds the set value. There have been various problems such as the control circuit for making the judgment becomes complicated. The present invention has been made to solve the above problems, and an object thereof is to obtain an induction heating cooker capable of accurately detecting boiling at low cost.

[Means for Solving the Problems]

The induction heating cooker according to the present invention includes a temperature detector for detecting a lower temperature of a top plate, a temperature rise rate measuring means for measuring a temperature rise rate, and an object to be heated according to a measurement result of the temperature rise rate measuring means. Water amount determining means for determining the amount of water, extension temperature determining means for determining the extension temperature based on the water amount determined by the water amount determining means, and controlling the heating amount of the heating element based on the output of the extension temperature determining means The heating control means and the temperature-based control means for selecting constant heating control or extended heating control by a signal from the temperature detector immediately after the start of control.

[Action]

The induction heating cooker in the present invention, depending on the temperature immediately after the start of control, selects constant heating control or extended heating control, and performs heating control until boiling detection is performed, therefore, while having a simple configuration, As a result, reliable control can be performed.

Examples of the invention

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, reference numeral 1 is a top plate made of a non-conductive material, and a pan 2 is placed on the top plate 1. Reference numeral 3 denotes water as an object to be heated which is accommodated in the pan 2, and 4 denotes a heating coil arranged at a lower portion of the top plate 1, which induction-heats the pan 2 by generating a high frequency magnetic field. Reference numeral 5 is a temperature detector for detecting the temperature of the top plate 1, and 6 is an input of the temperature detection signal supplied from the temperature detector 5, and the extension heating control and the constant heating control are performed depending on the temperature immediately after the start of the control. The temperature control selecting means for selecting either one is a temperature for measuring the temperature rise rate by inputting the temperature detection signal generated from the temperature detector 5 when the temperature-specific control selecting means 6 selects the extension heating control. Rise rate measuring means, 8 is the temperature rise rate measuring means 7
Water amount determining means for determining the amount of water contained in the pan 2 according to the output signal of the heating element, reference numeral 9 for heating extension temperature determining means for determining the heating extension temperature by the output of the water amount determination means 8, 10
Is heating control means for controlling the control circuit 33 for controlling the heating coil 4 according to the output of the heating extension temperature determining means 9. And the temperature-dependent control selection means in this case
6, the temperature rise rate measuring means 7, the water amount determining means 8, the heating extension temperature determining means 9, and the heating control means 10 are configured by a microcomputer 11. The operation of the induction heating cooker having the above configuration will be described below with reference to the flowchart showing the boiling detection program shown in FIG. First, when the boiling detection program is started after turning on a power switch (not shown), in step 14, the control circuit 33 controls the heating means 10 to supply the heating coil 4 with high-frequency power of, for example, 1300 W as the maximum heating amount.
Is controlled. Next, at step 15, the temperature detector 5 determines whether or not the present temperature is a predetermined temperature, which is, for example, 70 ° C. or higher. If the result of this determination is YES, the constant heating control A is selected, and if it is less than 70 ° C., it becomes NO and the extended heating control B is selected. Here, when the extension heating control B is selected, the temperature rise rate measuring means 7 measures the temperature rise rate. The first step in measuring the temperature rise rate
In step 16, it is judged whether or not it is the judgment start temperature (for example, 89 ° C. or higher), and if it is below the judgment start temperature, the judgment is NO and the operation returning to step 16 is repeated and waits. When the temperature rises above the judgment start temperature,
The result of the determination made in step 16 is YES, and the process proceeds to step 17. In step 17, measurement at time t ₀ is started, and the process proceeds to step 18. In step 18, a predetermined judgment end temperature (for example, 109 ° C. or higher)
It is determined whether or not Here, if the determination result in step 18 is NO, the control returns to step 18 to repeat the control to enter the standby state. Further, when the temperature rises to, for example, 109 ° C. or higher as a predetermined determination end temperature, the determination result in step 18 becomes YES and the process proceeds to step 19, whereby the measurement at time t ₀ is completed. Then, the process proceeds to step 20 in the water amount determination means 8. In step 20, the amount of water is determined based on the time t ₀ determined by the temperature rise rate measuring means 7. Here, the determination of the water amount will be described with reference to FIGS. 3 to 6. When the control start temperature of the temperature detector 5 is started from the same temperature in each of FIGS. 3 to 6, the water amount determination starts. It is represented by the time t ₀ from the temperature to the determination end temperature. In other words, when the amount of water as the object to be heated is small,
When the temperature rise rate becomes large and the time t ₀ becomes a small value, and conversely when the water amount is large, the temperature rise rate becomes small and the time
It is apparent from FIGS. 3 to 6 that t ₀ has a large value. Here, the rate of increase is branched into four patterns of steps 21 to 24 shown in the heating extension temperature determining means 9, and heating extension temperatures T ₀ , T ₁ , T ₂ and T ₃ are set. However, the heating extension temperature T ₀ ,
The relationship between T ₁ , T ₂ and T ₃ is T ₀ <T ₁ <T ₂ <T ₃ , for example T ₀ is 109 ° C, T ₁ is 115 ° C, T ₂ is 125 ° C and T ₃ is It has reached 130 ° C. Then, when the heating extension temperature is set by any of the corresponding steps 21 to 24, the process proceeds to step 25, and the comparison processing of the current temperature detected by the temperature detector 5 and the heating extension temperature is executed. . Here, if the present temperature> the heating extension temperature, it is determined that the boiling state has not been reached yet, and the process returns to step 25 to repeat the process to enter the standby state. If the current temperature is less than the heating extension temperature, it is determined that the boiling state has been detected, the process proceeds to step 26, the termination process is executed, and the execution of the boiling detection program is stopped. Next, when the constant heating control A is selected, the processing of step 24 in the heating extension temperature determining means 9 is executed,
The heating extension temperature T ₃ is set. In this way, if the heating extension temperature is set, the present temperature is detected by the temperature detector 5, and by comparing the present temperature with the heating extension temperature, if the present temperature> the heating extension temperature, the boiling state is detected. As a matter of course, the ending process shown in step 26 is executed to stop the execution of the boiling detection program.

【The invention's effect】

As described above, according to the present invention, since the boiling detection of the induction heating cooker is performed by using the conventional hardware, the function required by the software is obtained, so that the apparatus is inexpensive. In addition, various advantageous effects such as highly accurate temperature detection can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an induction heating cooker according to an embodiment of the present invention, FIG. 2 is a flow chart showing a boiling detection program used in FIG. 1, and FIGS. FIG. 7 is a temperature rise characteristic diagram for explaining the operation of detecting the amount of water from the rate, and FIG. 7 is a configuration diagram showing a conventional induction heating cooker. 1 is a top plate, 2 is a pan, 3 is water, 4 is a heating coil, 5 is a temperature detector, 6 is temperature-dependent control selection means, 7 is a temperature rise rate measuring means, 8 is a water amount judging means, and 9 is heating extension. Temperature determination means,
10 is heating control means, 11 is a microcomputer. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A temperature detector for detecting a lower temperature of a top plate,
Temperature rise rate measuring means for measuring the rate of temperature rise, water quantity judging means for judging the water quantity of the object to be heated according to the measurement result of the temperature rising rate measuring means, and extension temperature based on the water quantity judged by the water quantity judging means Heating extension temperature determining means, heating control means for controlling the heating amount of the heating body based on the output of the heating extension temperature determining means, and constant heating control and extension heating by the signal of the temperature detector immediately after the start of control. An induction heating cooker comprising: a temperature-dependent control selection unit that selects control.