JPH0640514B2 - Boiling detector - Google Patents

Description

The present invention relates to a boiling detection device for a heating cooker such as an electromagnetic cooker.

[Prior art]

In a conventional electromagnetic cooker, an induction heating coil 3 is arranged below a top plate 2 on which a cooking pot 1 is removably placed, as shown in FIG. 5, and at the center of the induction heating coil 3. A temperature sensor 6 that is positioned and supported by the heat sensitive plate 4 and the support 5 is arranged.

Then, the cooking pot 1 placed on the top plate 2
Is heated by the eddy current generated by the magnetic field generated from the induction heating coil 3, and the temperature sensor 6 indirectly detects the temperature of the cooking pot 1 via the top plate 2 to control the heating amount. It is supposed to do.

In recent electromagnetic cookers, a control circuit detects a gradient change in the detection signal from the temperature sensor 6, and the boiling of the load is detected by the gradient change.

[Problems to be solved by the invention]

However, in the case of detecting the boiling of the load by catching the temperature gradient change of the temperature sensor as in the above structure, it is necessary to accurately convey the temperature of the cooking pot 1 to the temperature sensor 6 because of the temperature control. Therefore, there is a drawback that the user must limit the warp of the pan bottom, the range of the water amount, the initial water temperature, etc., and the limitation of the initial temperature of the sensor, that is, the boiling detection directly and repeatedly. There was a drawback that you couldn't.

[Means for solving problems]

The present invention, a vibration detection means for detecting the vibration of the load, and a level determination means for outputting a signal to that effect when the vibration level detected by the vibration detection means is equal to or higher than a predetermined level,
The level determining means counts the number of output signals and determines that the load is boiling when the output number of the counted signals is equal to or more than a predetermined number within a predetermined time.

[Work]

According to the present invention, when the load reaches the boiling temperature, the vibration (hammer shock) due to the boiling of the load is detected by the vibration detecting means. Therefore, the boiling is detected by the conventional temperature control. It does not require various restrictions like the ones and can repeatedly perform boiling detection.

The discriminating means is for detecting whether the vibration is a one-time vibration or a vibration caused by boiling of the load.

〔Example〕

11 is a rectifying stack, 12 is a choke coil, 13 is a smoothing capacitor, 14 is an induction heating coil, 15 is a resonance capacitor, 16 is a switching element for flowing a high frequency current in the induction heating coil 14, 17 is a damper diode, 18 is a drive circuit for driving the switching element 16, 19 is a power supply circuit, 20 is a control circuit for controlling energization of the switching element 16, 21 is a display circuit, 2
Reference numeral 2 is an adjusting volume for adjusting the heating output, and 23 is a top plate for detachably mounting the cooking pot 24.

To describe a general heating operation, a control signal having a drive pulse width corresponding to the control potentiometer 22 is generated in the control circuit 20, and the switching element 16 is operated via the drive circuit 18 according to the drive pulse width control signal. O
Repeat N and OFF. Therefore, the induction heating coil 14
A high-frequency alternating current flows through this, an alternating magnetic field is generated thereby, and the cooking pot 24 is heated by the eddy current at this time. The amount of heating is adjusted by adjusting the adjusting volume 22.

Reference numeral 25 denotes a temperature sensor such as a thermistor attached in close contact with a heat sensitive plate 26 attached to the central portion of the lower surface of the top plate 23, which is supported by a support tool 27, and the cooking pot 24 of the cooking pot 24 is inserted via the top plate 23. It is designed to detect temperature. The detection signal detected by the temperature sensor 25 is input to the control circuit 20 and is controlled in the control circuit 20 so that the temperature of the cooking pot 24 becomes a preset predetermined temperature.

Reference numeral 28 denotes a vibration detecting means composed of a piezoelectric element or a semiconductor strain resistance type sensor which is attached in close contact with the heat sensitive plate 26, and detects vibration (hammer shock) of the cooking pot 24 through the top plate 23. That is, paying attention to the fact that the cooking pot 24 vibrates when the water or the like in the cooking pot 24 boils and boiled up, and whether or not the load is in a boiling state by detecting this vibration by the vibration detecting means 28. This is to detect whether or not (see FIG. 4).

The detection signal of the vibration detecting means 28 is converted into an electric signal and input to the control circuit 20, and the operation inside the control circuit 20 is performed as shown in the flowchart of FIG.

That is, after the initial setting, the vibration is measured, and it is determined whether or not the vibration is higher than a predetermined vibration level. When the vibration is higher than the predetermined vibration level, the counter is incremented by +1 and the vibration level is higher than the predetermined vibration level. Or not.

And, normally seen whether a predetermined time has passed T ₁ because it is "N", if "N" back at the first vibration level measurement, if "Y" counter count value N And the constant K are compared.

Then, in this step, "Y" is determined to be vibration due to boiling of the load, and normal output control, that is, output control using a temperature sensor or the like is performed.

If "N" in the above step, the process returns to the initial setting step, the count number N of the counter becomes 0, and the process returns to the first operation.

Further, if "Y" in the step of determining whether the second vibration level is large or small on the flowchart, the count value N of the counter is compared with the constant K, and if "N", the first vibration level is measured. Return to step. If "Y" is determined in the above step, it is determined that the vibration is caused by boiling of the load, and the normal output control is performed.

The above is the operation of the boiling detection device of the present invention, and by pressing a boiling detection button (not shown) provided on the cooker main body side, it is switched to the boiling detection mode (flow chart in FIG. 3). There is.

Therefore, according to the present invention, not the temperature control but the vibration at the time of load boiling is detected to detect whether or not it is boiling, so that the user is limited to the warp of the pan bottom, the range of the amount of water, or the initial water temperature as in the conventional case. It is not necessary to impose restrictions such as the limitation of the above, and since it is not related to the initial temperature of the sensor part, repeated boiling detection can be performed.

Although the embodiment of the boiling detection device of the present invention has been described based on the electromagnetic cooker, it goes without saying that it can be applied to other heating devices.

[Effect]

Since the present invention is configured as described above, the boiling detection function is not restricted by the conditions for detecting the temperature, there is no need to cool the main body, and continuous boiling detection is also possible. It is possible to exert a remarkable effect that it leads to improvement of usability and power saving performance.

Moreover, when the vibration level detected by the vibration detecting means is equal to or higher than the predetermined level, the level judging means outputs a signal to that effect, and the number of signals output from the level judging means is counted by the judging means. Since it is judged that the load is boiling when the output number of the signal that is output is equal to or greater than the predetermined number within the predetermined time, it is possible to reliably prevent erroneous detection due to vibration other than when the load is boiling. The boiling of can be detected.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of an electromagnetic cooker equipped with the device of the present invention,
FIG. 2 is an enlarged view of a main part of the same electromagnetic cooker, FIG. 3 is a flow chart of the device of the present invention, FIG. 4 is a sensor output of the device of the present invention and a detection waveform diagram corresponding thereto, and FIG. 5 is a conventional electromagnetic cooker. FIG. 20: control circuit, 28: vibration detection means.

Claims (1)

[Claims] 1. A vibration detecting means for detecting a vibration of a load, a level judging means for outputting a signal to that effect when the vibration level detected by the vibration detecting means is above a predetermined level, and the level judging means. A boiling detection device, comprising: a counting unit that counts the number of output signals from the device and determines that the load is boiling when the output number of the counted signals is a predetermined number or more within a predetermined time. .