JPH08233273A - Heat cooking appliance - Google Patents

Abstract

PURPOSE: To conduct cooking excellently irrespective of the amount of foodstuff, a supply voltage and a power supply frequency by a method wherein the number of square receivers placed in a heating chamber and the amount of the foodstuff put in the square receiver are recognized on the basis of information on the detected number of revolutions of a hot air circulating fan. CONSTITUTION: When square receivers 2 are put on two stages in a heating chamber 1 or the shape of foodstuff put in the receiver is large, a balance of circulation of hot air coming in from an intake port of the hot air and going out from an exhaust port thereof in the rear side of the heating chamber 1 is lost and the number of revolutions of a hot air circulating fan 4b is affected thereby and decreased. Based on information on the decreased number of revolutions of the hot air circulating fan 4b detected by a revolution number detecting means 6, in this state, a control part 8 detects indirectly the number of the square receivers 2 placed in the heating chamber 1 and the amount of the foodstuff put in the square receivers. Based on this detection, the number of revolutions is increased to about 1800RPM so as to make up for the insufficiency of torque, and a failure due to fluctuation of a voltage frequency is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating cooker for cooking food by utilizing hot air energy.

[0002]

2. Description of the Related Art Conventionally, a food heating device using a heating element has a sheathed heater, a flat heater, a quartz tube heater, etc. installed on the top and bottom of a heating chamber to heat food by natural convection from above and below. Was there. However, in recent years, it has been desired to heat a large amount of food at a time, and as a general method, a heating method is adopted so that a large amount of food can be cooked at a time by setting the food placing plate in the heating chamber in two stages. It is often seen that hot air circulation is used for efficient heating and cooking. There are two-stage cooking methods, one with two round plates and one with two square plates. In the former, the heating time according to the weight is set by the information from the weight sensor via the shaft supporting the round plate. And heat. Since the latter cannot directly detect the weight, methods such as detecting the rise of temperature in the heating chamber, estimating the amount of food by fuzzy reasoning, and determining the heating time are often used.

[0003]

In the case where hot air is circulated in the heating chamber during heating to heat food, the hot air circulating fan in the hot air generating unit provided outside the heating chamber rotates at the synchronous speed of the motor. However, if the speed of the motor itself is not controlled, the speed changes with the amount of food placed in the heating chamber, voltage fluctuations, and power supply frequency changes. Alternatively, depending on the place where one or a plurality of square plates are placed in the heating chamber, the balance between the intake and exhaust of the hot air circulation of the hot air generating unit may be disrupted and the rotation speed may be changed. Therefore, as the amount of load in cooking increases, the circulation of hot air deteriorates, causing uneven baking, and the motor overloads, causing a problem that the temperature of the winding of the motor rises. In the past, in order to eliminate uneven baking, the heating time was extended, the temperature inside the heating chamber was carefully controlled, the food was monitored to prevent burning, and the turntable was rotated during round plate cooking. In addition, it is necessary to provide a special heat exhausting means to prevent the temperature of the motor atmosphere from rising.

Particularly in cooking using a square plate, there is an example in which the weight is directly detected by a weight sensor or the like on a shelf portion supporting the square plate (Japanese Utility Model Laid-Open No. 60-86805), but the structure is complicated and it is difficult to realize. However, there were problems such as increase in cost and cost increase.

[0005]

In order to solve the above-mentioned problems, the present invention provides a heating chamber for storing foods, a square plate on which foods are placed, and a plurality of shelves for supporting the rectangular plates in the heating chambers. When,
In a heating cooker including a hot air generating unit having a hot air circulation fan that supplies hot air to a heating chamber and a rotation speed detection unit that detects the rotation speed of the hot air circulation fan, the hot air circulation fan detected by the rotation speed detection unit The control unit has means for recognizing the number of square plates placed in the heating chamber 1 and the amount of food items placed on the square plate based on the rotation speed information.

[0006]

If two square dishes are placed in the heating chamber or if food having a large shape is placed, the balance of the circulation of hot air into and out of the heating chamber is disturbed and the rotation speed of the hot air circulation fan 4b is affected.
The rotation speed decreases. In this state, the control unit determines the number of square plates placed in the heating chamber and the amount of food items placed on the square plate based on the reduced rotation number information of the hot air circulation fan detected by the rotation number detection means. It can be detected indirectly.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is a heating chamber for cooking food, 2 is a square plate on which food is placed, and 3 is a two-tiered shelf on which the square plate 2 is placed, which is provided in the heating chamber 1. Reference numeral 4 denotes a hot air generating unit, a heater 4a, a hot air circulating fan 4b and a case 4c.
And so on. Reference numeral 5 is a motor for driving the hot air circulation fan 4b, and 6 is a rotation speed detection means for detecting the rotation speed of the hot air circulation fan 4b. The rotation plate 9 mounted on the motor 5 and the rotation speed of the rotation plate 9 are detected by light. It is composed of a photocoupler 10. Reference numeral 7 is a triac for controlling the rotation speed of the hot air circulation fan 4b by a speed control means. Reference numeral 8 denotes a control unit composed of a microcomputer, which recognizes the number of square plates 2 placed in the heating chamber 1 and the amount of food placed on the square plate 2 based on the number of revolutions of the hot air circulation fan 4b from the number of revolutions detecting means 6. It has a means (for example, a data table, an arithmetic expression) to do.

Next, the operation of the thus constructed embodiment will be described.

Now, the cookie dough is put on the square plate 2, and the cookie dough is put on the shelves 3 and 3 in the heating chamber 1 one step each, for a total of two steps. At the same time as pressing the heating start button (not shown), hot air is blown from the hot air generating unit 4 onto the food. At this time, the motor 5 is supplied with an applied voltage that is controlled to be waved as shown in FIG. This is because the electric power can be further supplied to the motor 5 when the rotational speed of the hot air circulation fan 4b is lowered, and the phase is changed as the temperature of the winding of the motor 5 is increased by a simple method of changing the input phase. This is because the amount of power changes.

The speed control means 7 of the motor 5 is generally a method of controlling the current by using a DC motor, a method of controlling the frequency by an AC motor, or a method of fundamentally increasing the torque of the motor 5 to keep the rotation speed constant. Although it is known that it is difficult to install these complicated control systems in the recent low price competition of home appliances, it is necessary to change the voltage applied to the motor 5 by using a semiconductor power control element such as a triac. ing.

When the square plate 2 is cooked in one stage in the limited heating chamber 1, the hot air circulating in the heating chamber 1 is not disturbed and relatively smoothly circulates. Square plate 2
If the food is put in two stages or a large-sized food is put in, the balance of the amount of air coming in and out of the hot air intake hole (not shown) and the exhaust air hole (not shown) on the rear surface of the heating chamber 1 is lost, and the hot air circulation fan 4b. The engine speed is affected, and the engine speed also drops from 2000 RPM to 1500 RPM when there is no load. In this state, the control unit 8 compares the lowered rotation speed information of the hot air circulation fan 4b detected by the rotation speed detection unit 6 with a preset data table, and compares the number and the number of the square plates 2 placed in the heating chamber 1. The amount of food placed on the plate 2 can be indirectly detected. Further, when the number of rotations of the hot air circulation fan 4b is reduced, a sufficient amount of heat is not transmitted to the food and uneven baking occurs in the food, and the ambient temperature of a sensor unit (not shown) for controlling the temperature in the heating chamber 1 is also affected. Since the response also becomes slow, the wave application control of the voltage applied to the motor 5 is stopped as shown in FIG. 2 (B) and the rotation speed is increased to 1800 RPM to compensate for the torque shortage. Of course, at the product development stage, the normal rotation speed is set to around 1800 RPM, and a heating pattern that can be cooked at that rotation speed is established so that the rotation speed can be kept at 1800 RPM even if the load amount or power supply frequency changes. Leave. It is possible to obtain a uniform finish without uneven heating by always setting a constant rotation speed and air volume.
Further, it is possible to eliminate the influence on the temperature control.

Also, when a wide food having a diameter of 15 cm to 28 cm, such as a sponge cake, is placed on one square plate 2, the same phenomenon as described above occurs, and the same control should be performed. It is also possible to indirectly detect the weight and size of food.

[0014]

As described above, according to the present invention, the rotational speed of the hot air circulating fan is detected by the rotational speed detecting means during heating and is fed back to the control unit to indirectly control the number of square plates or the square plates. The amount of food placed on the can be detected, and the finished food can be cooked without failure due to fluctuations in power supply voltage and power supply frequency. Further, the weight detecting means such as a weight sensor can be removed, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view of a heating cooker showing an embodiment of the present invention.

FIG. 2 is a diagram showing a voltage applied to a motor of a hot air circulating fan of a heating cooker according to an embodiment of the present invention.

[Explanation of symbols]

 1 Heating Chamber 2 Square Plate 3 Shelf 4 Hot Air Generation Unit 4b Hot Air Circulation Fan 6 Rotation Speed Detection Means 8 Control Unit (Microcomputer)

Claims (1)

[Claims] 1. A heating chamber (1) for containing food, a square plate (2) for placing the food, and a plurality of shelves (3) for supporting the plate (2) in the heating chamber (1). A hot air generating unit (4) having a hot air circulation fan (4b) for supplying hot air to the heating chamber (1), and a rotation speed detection means (6) for detecting the rotation speed of the hot air circulation fan (4b). In the cooker
The number of the square plates (2) placed in the heating chamber (1) based on the rotation speed information of the hot air circulation fan (4b) detected by the rotation speed detecting means (6), and the square plate A heating cooker comprising a controller (8) having means for recognizing the amount of food placed on (2).