JPH06241476A - Heating device - Google Patents

Abstract

PURPOSE:To heat quickly without uneven heating by a method wherein electric power is supplied mainly to a near infrared heat generating body on a ceiling in the first half of heating while the power is supplied to a far infrared heat generating body, arranged mainly around the near infrared heat generating body, in the second half of the heating CONSTITUTION:A command from a heating key 5 is read through a control unit 10. The control unit 10 drives a plurality of drivers 11 in accordance with the kind of a material to be heated, which is read by the control unit 10, to supply electric power with a predetermined conduction ratio to mainly a radiation type heat generating body 8, arranged on the ceiling of a heating chamber 3, and a surface type heat generating body 9 on the same as well as another surface type heat generating body 12 on the bottom surface. When a temperature sensor detects that the surface temperature of the material to be heated has arrived at a predetermined temperature or 100 deg.C, for example, the supply of power is switched to supply the power mainly to the surface type heat generating body 9 and the radiation type heat generating body 8 as well as the surface type heat generating body 12 with a predetermined conduction ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of energization of a heating element in a heating device.

[0002]

2. Description of the Related Art A heating cooker disclosed in Japanese Patent Publication No. 61-21331 is radiated by coating a plurality of heaters having different calorific values with a ceramic material and appropriately switching the heaters to control energization. The infrared wavelength is effectively selected and used.

According to the above-mentioned conventional example, there are a case where the inside of the food is mainly heated and a case where the surface is heated, that is, the case where the surface of the food is mainly browned. It is said that effective selective use is desirable. Therefore, a large-capacity heater and a small-capacity heater are arranged side by side, and a heating plate having an outer surface covered with a ceramic material and formed into a plate shape is provided, and which heater is energized is controlled by a changeover switch on the control panel. Then, the wavelength of infrared rays radiated from the heating plate is changed to change the degree of heat penetration into food. Since the heating value of each heater is different, infrared rays with different wavelengths are radiated from the ceramic material, and far infrared rays are radiated from the small-capacity heater due to the low temperature, and the heat penetrates into the inside of the food, such as chunk meat and cake. Suitable for cooking. On the contrary, the large-capacity heater emits near-infrared rays due to high temperature,
The surface of the food is browned so that it is suitable for grilled fish cooking.

[0004]

However, in the structure in which the heaters having different capacities are selectively switched depending on the food as described above, the large-capacity heater allows the area to be evenly burned, and the small meat or fish fillets are grilled. Even if I could do it, when I put many thin fish such as saury and gratin on one plate, the surroundings did not burn. On the other hand, a small-capacity heater generally has a long heater length and can easily heat a wide range without unevenness, but since the amount of radiation is small, baking sweets is not suitable for meat and fish.

The present invention solves the above-mentioned conventional problems, and its first object is to heat an object to be heated quickly and uniformly. Further, a second object is to automatically optimize the infrared wavelength and the radiation distribution of the heating element according to the object to be heated and automatically switch the heating.

[0006]

In order to achieve the above-mentioned first object, the heating device of the present invention comprises a first heating element and a second heating element and a control section, and also achieves the second object. In addition, the control unit for alternately switching the power supply to the heating element and the detection unit for directly or indirectly detecting the surface temperature of the object to be heated are provided.

[0007]

The heating device of the present invention has the above-described structure.
The infrared wavelength and the radiation distribution of the heating element can be optimized according to the type of the object to be heated and the heating can be speedily performed without uneven heating. Further, the temperature detecting means detects the surface temperature of the food, so that the control section can automatically switch the power supply to the plurality of heating elements.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A heating device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front perspective view of a heating apparatus according to an embodiment of the present invention. A door 2 is rotatably supported by a front surface of a main body 1 and a heating chamber 3 in which an object to be heated is stored. The opening is blocked. On the operation panel 4, a heating key 5 for instructing the type of object to be heated, heating category, etc. is arranged. Temperature sensor 6 that indirectly detects the food surface temperature on the inside of the refrigerator
Are arranged.

FIG. 2 is a plan view of an essential part of a heating device according to an embodiment of the present invention. A case is shown in which a small hole group 7 is bored in the central portion of the ceiling of the heating chamber, and a radiation type heating element 8 is installed as a first heating element facing the small hole group 7. The radiant heating element 8 is formed by a hollow protective tube having a circular or elliptical cross section, which is an insulating material having a good infrared transmittance, such as a quartz tube or a crystallized glass tube, and a heating wire surrounded by the protective tube. .

Further, a case is shown in which the planar heating element 9 is annularly arranged as the second heating element around the ceiling of the heating chamber. As the sheet heating element, for example, the sheet heater disclosed in Japanese Patent Publication No. 54138/1992 can be used. That is, the heating element is wound around a winding frame made of a heat-resistant insulating material such as mica, and the upper and lower sides thereof are also sandwiched by an insulating material such as mica and pressed against the ceiling of the heating chamber from the outside. No through hole is formed in the ceiling wall surface facing the sheet heater.

FIG. 3 is a diagram showing the wavelength and radiation intensity of infrared rays radiated by the heating element group according to the present invention. The horizontal axis represents the infrared wavelength and the vertical axis represents the radiation intensity, and the relationship between the two is shown using the heater temperature as a parameter. Group A shows the characteristics of the radiant heating element of FIG. 2, and group B shows the characteristics of the sheet heating element. The heater temperature is realized by intermittently supplying electric power to the heater and changing the duty ratio thereof.
That is, the maximum temperature is obtained by continuously energizing, and the heater temperature decreases as the off time is lengthened.

FIG. 4 is a diagram showing the heat distribution of the heating element group. FIG. 4A shows the heat distribution pattern of the radiation type heating element.
(B) shows the heat distribution pattern of the planar heating element. As shown in the figure, the radiant heating element has a structure in which strong radiation is concentrated in the center, and has a large difference from the surroundings. On the other hand, in the planar heating element, gentle radiation is uniformly radiated over the entire surface.

For comparison, how to raise the temperature of the mounting table when only one of the heating elements is energized is shown.

The numerical values in the figure indicate the radiation level, and the higher the numerical value, the higher the radiation level. That is, the level 5 has the highest radiation intensity.

FIG. 5 shows the temperature rise in the center of the mounting table, and FIG. 6 shows how the temperature around the mounting table rises. In FIG. 5 and FIG. 6, the solid line a indicates that only the radiation type heating element is continuously energized. What is represented by the broken line b is one in which only the planar heating element is continuously energized. From the solid lines a and b, it can be seen that the radiation type heating element rapidly rises in temperature and reaches a high temperature, but the planar heating element does not rise as quickly as a radiation type heating element.

FIG. 7 shows how the temperature of the heater rises when electricity is mainly applied to the radiant heating element in the first half of heating and electricity is switched mainly to the sheet heating element in the latter half. (A) represents the temperature of the radiant heating element, and (b) represents the temperature of the planar heating element. (C) represents the surface temperature of the object to be heated,
(D) represents the temperature inside the object to be heated. In the first half of heating, by heating with a radiant heating element with a good rising speed, the surface temperature of the object to be heated is quickly raised to give a brown color, then the electricity is switched to the planar heating element to slowly heat it from the inside. Heat up to. In the first half, when electricity is mainly applied to the radiant heating element, heat is also transmitted to the sheet heating elements arranged in the surroundings to be warmed up, so that the rising after the energization is switched to the sheet heating element having a slow rise is quickened. Since the radiant heating element carries over the object to be heated with the residual heat even after the energization is switched to the planar heating element, the timing of switching the energization is such that when the object to be heated begins to have a brown color, that is, the surface temperature is approximately 100 degrees Celsius. It's time to reach.

FIG. 8 is a block diagram showing an embodiment of the configuration of the present invention. The command input from the heating key 5 is decoded by the control unit 10. The control unit 10 can be composed of, for example, a microcomputer. Depending on the type of the object to be heated input from the heating key 5, the control unit 10 mainly uses the radiation type heating element 8 arranged on the ceiling of the heating chamber 3 via the plurality of drivers 11, and the sheet heating element 9. Further, the sheet heating element 12 arranged on the bottom surface of the heating chamber 3 is supplied with power at a predetermined energization ratio. The temperature sensor 6 indirectly detects the surface temperature of the object to be heated, and when the temperature reaches a predetermined temperature, the planar heating element 9 is mainly used and the radiation type heating element 8 and the planar heating element 12 are energized in a predetermined manner. Switch the power supply to the ratio.

FIG. 9 is a time chart showing the energization of these three kinds of heating elements. That is, (a) shows power supply to the radiant heating element 8, (b) shows power supply to the sheet heating element 9 on the ceiling, and (c) shows power supply to the sheet heating element 12 on the bottom surface. . A configuration for switching successively feeding to the heating element of each in this embodiment, the commanded energization ratio T _A / T _B, and one period length T _o of energization of the ceiling radiation heating elements and the planar heating element It changes according to the heating key. In the first half of heating, T _A / T _B is large, and in the second half, T _A '/ T _B ' is small. The energization ratio is changed depending on the type of heating key. It is of course possible to make the first half T _B zero and the second half T _A 'zero.

In this embodiment, the planar heating element on the bottom of the heating chamber is also configured to be energized alternately like the heating element on the ceiling. However, the watt density of the three heating elements is appropriately selected and the ceiling heating element on the ceiling is selected. It is also possible to alternately energize only two kinds of heating elements and continuously energize the planar heating element on the bottom surface. Further, the driver 11 is not a relay-like on / off control but a semiconductor switch capable of continuously controlling a current value, and
The same effect can be obtained by changing the duty ratio instead of changing the off time.

[0021]

As described above, the following effects can be obtained in the heating device of the present invention.

(1) A heating element that emits near-infrared rays mainly in the center of the heating chamber in the first half of heating in accordance with the type of the object to be heated, which is instructed by the heating key, and mainly in the surroundings of the heating chamber in the latter half of heating. By heating with a heating element that emits far-infrared rays, the infrared wavelength and radiation distribution of the heating element can be optimized and heating can be performed quickly without uneven heating.

(2) Since the temperature detecting means detects the surface temperature of the food, the control section can automatically switch the power supply to a plurality of heating elements, and the heating elements can be changed according to the kind of the object to be heated. It is possible to finish both the outside and the inside of the object to be heated in a good condition by optimizing the infrared wavelength and the radiation distribution of.

[Brief description of drawings]

FIG. 1 is a front perspective view of a heating device according to an embodiment of the present invention.

FIG. 2 is a plan view of a heating element of the heating device.

FIG. 3 is a diagram showing the infrared wavelength and radiation intensity of the heating element.

FIG. 4 is a diagram showing a heat distribution on a mounting surface of the heating device.

FIG. 5 is a diagram showing a temperature rise in a central portion on a mounting surface of the heating device.

FIG. 6 is a diagram showing a temperature rise around a mounting surface of the heating device.

FIG. 7 is a diagram showing a temperature rise of a heating element of the heating device and a temperature rise of an object to be heated.

FIG. 8 is a block diagram showing a configuration of a heating device.

FIG. 9 is a time chart showing power supply to a heating element of the heating device.

[Explanation of symbols]

 3 heating chamber 5 heating key 6 temperature detecting means 8 first heating element (radiant heating element) 9 second heating element (planar heating element) 10 control unit

Claims (2)

[Claims] 1. A heating chamber for accommodating an object to be heated, a heating key for instructing the type of the object to be heated, a first heating element for radiating near infrared rays to a central portion of the ceiling of the heating chamber, A second heating element that radiates far infrared rays around one heating element, and a control unit that alternately controls power supply to the heating element,
A heating device configured to supply power mainly to the first heating element in the first half of heating and mainly to the second heating element in the second half of heating. 2. A temperature detecting means is provided, and when the power supply from the first heating element to the second heating element is switched, the surface temperature of the object to be heated is detected directly or indirectly by the temperature detecting means. The heating device according to claim 1, which is a time point when the temperature reaches a certain degree.