JP2785344B2 - Induction heating cooker - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an induction heating cooker provided with a temperature sensor.

2. Description of the Related Art FIGS. 3 and 4 show a configuration of an induction heating cooker provided with a conventional temperature sensor. FIG. 3 is a sectional view of the main body,
FIG. 4 is an external perspective view of the main body. FIG. 3 and FIG.
This will be described with reference to the drawings.

A temperature sensor 4 is provided on the back surface of the top plate 2 to detect the temperature of the oil 8 in the pot 1 which is the object to be heated on the top plate 2 constituting the upper surface of the main body 3. As the temperature sensor 4, an inexpensive and easy-to-handle thermistor is often used. Then, the temperature of the thermistor is converted into a voltage, the change in the divided voltage due to the thermistor and the resistance is read, and the heating power to the pot is controlled by the energization ratio to the heating coil 5 so that the voltage is maintained at a predetermined voltage. Then, the temperature of the food in the pot is adjusted to a desired one. A high-frequency current is supplied to the heating coil 5 from an inverter circuit 6 driven by a control circuit 7, and the pot 1 is heated by electromagnetic induction at that time.

Problems to be Solved by the Invention However, in the conventional configuration, the temperature sensor 4 has the following problem because the temperature of the pot is detected by the heat conduction of the inclusion via the inclusion called the top plate 2.

 Hereinafter, description will be made with reference to FIGS. 5 and 6.

FIG. 5 shows a change state of the oil temperature Toil and the temperature sensor temperature Tth when heating the oil from the room temperature when cooking the tempura with the oil in the pot.

FIG. 6 is a partially enlarged view showing a configuration in which the temperature of the pan is detected by a temperature sensor. Since only the pot 1 is heated by the heating principle of the induction heating cooker, the heat generated there heats the oil in the pot by heat conduction and also heats the temperature sensor 4 by the heat conduction of the top plate 2. Then, as the oil temperature Toil increases, the temperature of the temperature sensor 4 also increases. On the other hand, the set temperature determined by the temperature setting means has a certain temperature range (TH-TL) hysteresis. When the temperature sensor temperature reaches the upper limit temperature TH, the power supply to the heating coil 5 is stopped, and when the temperature sensor temperature reaches the lower limit temperature TL, the power supply to the heating coil 5 is performed again. In this way, when the amount of heat dissipated into the atmosphere and the amount of heating from the heating coil 5 are in an equilibrium state, the operation of stopping power supply for Δt ₁ hour and repeating power supply for Δt ₂ hours is repeated.

In such a state, when the food is put into the oil, the amount of heat of the oil is absorbed by the food, so that the oil temperature decreases, and the temperature sensor temperature decreases later. Until now, the heat generated in the pan has heated only the oil in the pan, but the heat capacity of the object to be heated in the pan is increased because the cooking is added to the oil. Further, while the temperature of the temperature sensor 4 is also changing due to the heat conduction of the top plate 2, the influence of the temperature of the heated pot itself is larger than the temperature of the oil during the energizing operation of the heating coil 5, and This is due to heat conduction from the temperature of the pot exposed to the oil during the stop of energization, and the influence of the oil temperature is greater than during the energization operation.

Therefore, the temperature sensor temperature rise rate during the energization operation becomes slower by the increase in the heat capacity of the object to be heated as compared to before the food is poured into the oil, but as described above, the pot is heated as described above. The effect of heat conduction from the temperature itself (Tpan) is large, and the energization time Δt ₄ is not much different from Δt ₂ . Further, Δt ₃ becomes shorter than Δt ₁ due to the effect of the oil temperature drop in the temperature sensor temperature decrease rate during the stop of energization.
Therefore, the energization ratio before and after the food is put into the oil is Δt ₂ / Δt ₁ <Δt ₄ / Δt ₃ .

After the food is poured into the oil in this manner, the energization ratio increases and the temperature of the object to be heated is raised, but the amount of oil generally used for tempura cooking at home is determined by the amount of oil in the food. Since the heat capacity is not so large that it can be neglected, there is a problem that the load of the heat capacity of the heated object increases after the cooked product is put into the oil, and it takes time to return the temperature of the heated object. I do.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has an object to speed up the recovery of the temperature of a body to be heated even in an amount of oil generally used for cooking tempura at home.

Means for Solving the Problems In order to achieve the above object, the present invention provides a method for stopping the supply of electricity when the amount of heat dissipated into the atmosphere and the amount of heat from the heating coil are in a thermal equilibrium state before the food is put into oil. Storage means for storing a time ratio (Δt ₂ / Δt ₁ ) between the time Δt ₁ and the energization time Δt _2, and an energization ratio (Δt ₄ / Δt) after the contents of the storage means and the cooked food are put into oil ₃ ), and when the difference {(Δt ₄ / Δt ₃ ) − (Δt ₂ / Δt ₁ )} exceeds a certain value, the output value of the temperature setting means is set to the high temperature setting side. The correction means for correcting the error is provided.

Effect of the Invention With the above configuration, the present invention detects a decrease in the oil temperature by reading a change in the energization ratio when the food is put into the oil, and at this time, outputs the output value of the temperature setting means to the high temperature setting side. To greatly increase the energization ratio,
The lowered oil temperature can be quickly restored.

Embodiment Hereinafter, based on one embodiment of the present invention, FIG.
This will be described with reference to the drawings.

A temperature signal of the temperature sensor 4 attached to the back surface of the top plate by pressing is input to the control circuit 7, converted into an electric signal A by the temperature detecting means 11 and input to one of the first comparing means 13.

The temperature set by the cooker is set by the temperature setting means 12, and the electric signal B is sent through the adder 20 to the first comparison means 13.
To the other side.

The first comparing means 13 includes a temperature detecting means 11 and a temperature setting means.
Judgment of the magnitude relationship between the two inputs from 12 and temperature detection means
When the output A is higher than the temperature setting means 12 output B, a heating stop signal is sent to the thermal power control means 14 and the temperature detection means 11 output A
Is smaller than the output B of the temperature setting means 12, a heating operation signal is inputted to the heating power adjusting means 14.

The time ratio calculation means 16 calculates the time ratio between the heating stop signal and the heating operation signal from the first comparison means 13 as needed, and outputs the result value C to the storage means 17 and the second comparison means 18.

The storage means 17 stores the output (C = C ₀ = Δt ₂ / Δt ₁ ) of the time ratio calculation means 16 when the temperature of the oil 8 as the object to be heated reaches the temperature set by the temperature setting means 12. The timing is determined after the first comparing means 13 first outputs the heating stop signal and the temperature of the oil 8 and the temperature sensor 4.
This is performed after waiting for a certain time until the temperature difference from the temperature, that is, the so-called thermal resistance is stabilized. At this time, the value of the predetermined time for standby may be set to a unique value determined by the cooling condition having the cooker, the heat receiving structure of the temperature sensor 4, and the like.

Further, at this time, when the oil temperature has reached the set temperature, it is conceivable to notify the user with a buzzer sound or a lamp.

After the signal _C0 is transmitted from the time ratio calculating means 16 to the storage means 17 in this manner, the output (C = Δt ₄ / Δt ₃ ) of the time ratio calculating means 16 is stored in the second comparing means 18. The output of the means 17 (C = C ₀ = Δt ₂ / Δt ₁ ) is compared, and when the difference between the two outputs exceeds a certain value, the adder 19
The signal b is output to 20, and the value (B + b) added to the output of the temperature setting means 12 becomes the input value of the first comparing means 13.

In this manner, a decrease in the oil temperature due to the input of the food is detected by reading the value of {(Δt ₄ / Δt ₃ ) − (Δt ₂ / Δt ₁ )}, and the output of the temperature setting means 12 is corrected by the correction means. By adding the outputs of 19 and changing the set value to the high temperature side by the added amount, the oil temperature can be returned quickly.

It is also conceivable to set the output of the temperature setting means 12 higher than at the beginning of heating.However, if this is done, the overshoot at the time of oil temperature rising from room temperature or the oil temperature at the time of stabilization before the addition of food will be more than necessary. There are also problems such as high oil fumes and poor oil quality. However, according to the present invention, the above-mentioned problem can be prevented beforehand by maintaining an appropriate temperature and changing the output of the temperature setting means 12 to the high temperature side only when the oil temperature decreases.

Effects of the Invention As is apparent from the above embodiments, according to the present invention, means for detecting a decrease in oil temperature due to the introduction of food and automatically changing the temperature setting level to a higher temperature side than the initial level is provided. Thus, it is possible to provide a heating cooker that can quickly recover the temperature of oil and can cook tempura dishes well.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control circuit according to an embodiment of the present invention, FIG. 2 is a state change characteristic diagram of the oil temperature and the temperature sensor temperature, FIG. 3 is a sectional configuration view of the main body, and FIG. FIG. 5 is a perspective view showing a conventional state change characteristic between oil temperature and temperature sensor temperature, and FIG. 6 is an enlarged view of a temperature sensor mounting portion. 4 temperature sensor, 11 temperature detecting means, 12 temperature setting means, 13 first comparing means, 14 thermal power adjusting means, 16 time ratio calculating means, 17 storage means, 18 second comparing means, 19 correcting means.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-181092 (JP, A) JP-A-1-105492 (JP, A) JP-A-1-109686 (JP, A) JP-A-61-106 191322 (JP, A) JP-A-60-170182 (JP, A) JP-A-61-190889 (JP, A) JP-A-61-273890 (JP, A) JP-A-64-89277 (JP, A) Shokai Sho 62-153790 (JP, U) Shokai Hei 1-63094 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05B 6/12

Claims (1)

(57) [Claims] A temperature sensor provided in the main body for detecting a temperature of an object to be heated mounted on an upper surface of the main body; a temperature detecting means for converting a temperature detected by the temperature sensor into a signal; Temperature setting means for setting the temperature of an object; first comparing means for judging the magnitude of each output of the temperature detecting means and the temperature setting means; and a heating coil output determined by an output signal of the first comparing means. Heating power adjusting means, an output signal of the first comparing means, a time ratio calculating means for calculating a time ratio at which the temperature detecting means output is large, and a temperature of the object to be heated is determined by the temperature setting means. Storage means for storing the output of the time ratio calculation means when the temperature reaches the predetermined temperature, and second comparison means for comparing the output of the time ratio calculation means with the output of the storage means. Time ratio calculation by means Induction heating cooker difference between said storage means and output stage output is characterized by comprising a correction means for correcting the output value of the temperature setting means it becomes more than a certain value in the high temperature setting side.