JPS62108490A - Induction heating cooker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an induction heating cooker.

2. Description of the Related Art In general, this type of induction heating cooker has a structure as shown in FIG. That is, the main components are a heating coil 1 that generates high-frequency electromagnetic waves, a control circuit 2 that controls it, and a plate 4 on which a pot 3 to be heated is placed, and as shown in FIG. A coil 1 is connected in series with a transistor 5 and in parallel with a resonance capacitor 6.
The control circuit 2 turns the transistor 5 ON and OFF, causes a high-frequency current to flow through the heating coil 1 to generate electromagnetic waves, and generates an eddy current in the pot 3 to heat the pot 3 directly. Furthermore, a temperature detection element 7 such as a thermistor for detecting the temperature of the pot 3 is provided on the lower surface of the plate 4. By the way, a conventional detection device for detecting an excessive temperature rise in the pot 3, that is, an abnormality in the body, etc., has a temperature detection element 7 at a certain temperature (T2 in the figure), as shown in the graph of FIG. When detected, high-frequency oscillation is stopped, and heating of the object to be heated, such as the pot 3, is stopped.

Problems to be Solved by the Invention However, the temperature T2 that prevents excessive temperature rise in conventional temperature detection devices is the maximum temperature T2 required for actual cooking such as cooking with oil.
Since it is set higher than 1, if you leave it in a state where the amount of oil is small when cooking with oil, the temperature of the oil will rise very quickly, but the reaction of the temperature detection element will be slow, so it will not be detected. The temperature of the oil reaches the ignition temperature before the element reaches T2, causing the oil to catch fire, which is dangerous.

This is due to the fact that the temperature sensing element is located under a ceramic plate that does not conduct heat well, resulting in a slow response. It is undesirable to bring out the element to improve the reaction, as it would eliminate one of the features of the electromagnetic cooker, and conventionally, T2 was used to suppress oil ignition as much as possible.
Therefore, it is necessary to set the cooking temperature T1 lower than T2, resulting in the inconvenience that the temperature necessary for cooking cannot be obtained.

Therefore, the present invention takes into account the above-mentioned conventional problems and aims to prevent oil from igniting even if the temperature sensing element does not come into direct contact with a pot or the like.

Means for solving the problems and technical means of the present invention for solving the above problems are such that heating is stopped only when the temperature of the object to be heated rises within a certain period of time.

For production The effect of this technical means is as follows.

In other words, when cooking with oil and the amount of oil is small, if you leave it without cooking, the temperature of the oil will rise rapidly.
The temperature detection element also detects the temperature rise, and if only the rise in temperature is determined within a certain period of time and heating is stopped, the oil will not ignite. However, during cooking, the temperature fluctuates up and down, so you can cook without any problems without having to stop heating.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

The structure is the same as that described in the conventional example, but the configuration of the control circuit 2 functions as shown in the flowchart shown in FIG. That is, when the power of the electromagnetic cooker is turned on, a high-frequency current flows through the heating coil due to the action of the control circuit 2, generating electromagnetic waves and heating the pot 3. At this time, a timer built in the control circuit 2 is activated, and the signal from the temperature detection element 7 does not enter the control circuit 2 for a time t1 after the power is turned on. After the time t1 has elapsed, the timer stops, a signal from the temperature detection element 7 is input to the control circuit 2, and the temperature detection state is known. In this state, the control circuit 2 controls the temperature sensing element 7 during the period tS.
It is determined whether the signal from is only a rising value, and if there is only a rising value, heating is stopped. If there is not only a rising value, that is, if there is an upward or downward fluctuation in the signal, heating is continued. The relationship between temperature and time for this temperature detection is shown in FIG.

Effects of the Invention The present invention stops heating when the temperature rises during a certain period of time t2, and there is no risk of oil ignition due to abnormal heating, and the cooking temperature is also irrelevant. Therefore, unlike conventional methods, the original function of the cooker, which is to lower the cooking temperature to ensure safety, will not be inhibited. In addition, since it detects a rise in temperature, even if the temperature detection reaction is slow, it is easy to detect a rise just by changing the fluctuation curve. Temperature detection under a ceramic plate can also be detected sufficiently, making it easy to clean. Ease of use and good appearance can be ensured.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between temperature and time for temperature detection in an electromagnetic cooker according to an embodiment of the present invention, FIG. 2 is a flowchart showing the function of the same control circuit, and FIG. Fig. 4 is a longitudinal sectional view showing the structure of the cooker, Fig. 4 is a circuit diagram of the same, and Fig. 5 is a graph showing the relationship between temperature and time for temperature detection in a conventional electromagnetic cooker.・Heating coil, 2... Control circuit (
control device), 3... object to be heated, 4...
Plate, 7...Temperature sensing element. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 Figure 3 Figure 45! J

Claims (1)

[Claims] A heating coil, a plate on which the object to be heated is placed, a detection element disposed within this plate or at the bottom of the plate to detect the temperature of the object to be heated on the plate, and a signal from this detection element that generates oscillation. The control device includes a timer means for continuing oscillation to the heating coil for a predetermined period of time at the time of initial energization, and a timer means for detecting a signal from the temperature sensing element after a predetermined period of time in the control device. An induction heating cooker comprising a stop means for stopping oscillation when the temperature of a heated object rises within a certain period of time.