JPH02197722A - Electric cooking apparatus - Google Patents

Abstract

PURPOSE:To minimize the number of times of feeding and cutting off a current flowing to a lamp heater or the number of times of a great change in a current, and to prolong the life of the lamp heater by gradually reducing the output from the lamp heater each time a temperature detecting means for detecting the atmospheric temperature of the lamp heater detects a predetermined temperature and higher in and after a predetermined period of time. CONSTITUTION:In the title cooking apparatus, a temperature in a closed heating unit 2, namely, the atmospheric temperature of halogen lamps 3 is detected by a thermostat 8. Furthermore, a controller is programmed so as to gradually reduce the output from the halogen lamps 3 by 5% of their maximum output at each step during an ON period subsequent to each occasion that the thermostat 8 detects a predetermined temperature or higher to be turned OFF in and after a predetermined period of time. According to this constitution, the output from the lamps 3, namely, the heating rate of the same is automatically regulated so as to be balanced at a final stage with the amount of heat which is absorbed to a pan and the like and, thereafter, a current is continuously fed to the lamps 3. Moreover, since the output from the lamps 3 gradually approaches to the amount of heat which is absorbed to a pan and the like, the period of feeding and cutting off a current flowing to the lamps 3 gradually becomes longer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electric cooker using a lamp heater as a heat source.

(Prior Art) In this type of electric and thermal equipment that has been considered in the past, a halogen lamp is generally used as a lamp heater, and the object to be heated is heated by the heat generated by this halogen lamp. ing.

Specifically, the heating unit is constructed by covering the periphery and bottom of a group of multiple halogen lamps with a heat insulator, and further covers the upper surface of the heat insulator with a light-transmitting top plate made of heat-resistant glass or the like. Then, a cooking container such as a pot is placed on the top plate, and the object placed in the pot is cooked using the heat emitted by the halogen lamp.

In such an electric cooker, heat emitted from a halogen lamp is transmitted to a pot (an object to be heated) by radiation or conduction via a top plate. The heat capacity of this top plate is relatively large, and the temperature of the top plate does not rise easily at the start of heating, resulting in poor heat conduction through the top plate and poor rise in temperature of the cooking container. Therefore, high output (2KW) halogen lamps have been used conventionally.

On the other hand, in this electric cooker, in order to increase thermal efficiency, the heat insulator and the top plate are brought into close contact with each other to form a closed space inside the heating unit. Therefore, when a halogen lamp is continuously energized, the ambient temperature of the halogen lamp, that is, the air temperature inside the heating unit, gradually rises, and the heat resistance limit temperature (
, 850°C).

(Problem to be Solved by the Invention) Therefore, in the conventional electric cooker, a thermostat is provided as a temperature detection means for detecting the temperature inside the heating unit throat, and when the inside of the heating unit reaches a predetermined temperature, I tried to cut off the power to Genlanbu. However, in this one, when the /%logen lamp is re-energized,
The temperature inside the heating unit immediately rises and the /% halogen lamp is cut off again, which is repeated in short cycles, resulting in a problem that the life of the halogen lamp is shortened. In other words, a pot with poor heat absorption, such as a pot with good light reflectivity, will reflect radiant heat, which will trap heat inside the heating unit, causing the thermostat to turn off immediately when the halogen lamp is turned on. As a result, the halogen lamp is frequently turned on and off (see Figure 10). In addition, even in a pan with a darkened bottom and good heat absorption, as shown in FIG. 9, electricity is repeatedly turned on and off in a fairly short period, although not as frequently as in a pot with poor heat absorption. In addition, Figures 9 and 10
The figure shows the on/off operation mode of the thermostat, the surface temperature of the outer tube of the heat-sensitive part of the thermostat (which will become clear from the explanation of the example later), and the temperature of the halogen lamp when heating 2 g of water at a room temperature of 23 to 25 °C. The relationship with changes in the surface temperature of the bulb is shown.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to reduce the number of times the lamp heater is turned on and off, or the number of times the current of the lamp heater changes greatly.
An object of the present invention is to provide an electric cooker capable of extending the life of a lamp heater.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the electric cooker of the present invention is provided with temperature detection means for detecting the ambient temperature of the lamp heater, and this temperature detection means The lamp heater is provided with an output control means that gradually reduces the output of the lamp heater each time a predetermined temperature or higher is detected after the specified time.

(Function) When the lamp heater is energized to start heating, the ambient temperature of the lamp heater gradually rises. Then, when the temperature detection means detects a temperature equal to or higher than a predetermined temperature after a predetermined time, the output of the lamp heater is reduced each time the temperature is detected. This means that the output (calorific value) of the lamp heater is automatically adjusted to be in balance with the amount of heat taken by the object to be heated (such as a pot containing the object to be cooked). Therefore, irrespective of the difference in the heat absorption rate of the object to be heated, the number of times the lamp heater is turned on and off, or the number of times the current of the lamp heater increases or decreases significantly becomes longer, resulting in a longer life.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

First, as shown in FIG. 3, the outer frame 1 of the electric cooking appliance is formed into a flat rectangular box shape, and heating units 2 are disposed at, for example, three locations inside the outer frame 1. As shown in FIGS. 4 and 5, these heating units 2 are constructed by sandwiching a plurality of halogen lamps 3 as lamp heaters, for example four each, between upper and lower oblong insulators 4.5. Lower insulation 5
is fixed to the inner bottom surface of the outer frame 1 by a saucer 6.

The upper surface of the heating element 4 of each heating unit 2 is covered with a translucent top plate 7 made of heat-resistant glass or the like, and the top plate 7 is in close contact with the heating element 4. The inside of the heating unit 2 is sealed. The temperature inside this sealed heating unit 2, and therefore the ambient temperature of the halogen lamp 3, is detected by a thermostat 8 as temperature detection means. This thermostat 8 includes a heat sensitive part 9 which is formed by disposing a metal rod (not shown) that expands and contracts according to temperature changes in a metal outer tube 9a, and a switch that is turned on and off by the expansion and contraction of the metal rod of this heat sensitive part 9. The heat sensitive part 9 is arranged in the heating unit 2,
The switch section 10 is arranged outside the heating unit 2.

Note that this thermostat 8 is designed to turn off at temperatures above 750°C. Further, an operation panel 11 is provided on the outer frame 1 in parallel with the top plate 7. This JAY panel 11 has "on" and "off" buttons for starting and stopping heating, as shown in FIG.
"input upJ" and "input down" for each switch 12 and 13, halogen lamp 3 heat generation (input amount) one week adjustment
J] 4 and 15 are provided, and
A plurality of light emitting diodes 16 are provided for displaying the magnitude of input to the halogen lamp 3. Although the various switches 12 to 15 and the light emitting diodes 16 described above are provided in a one-to-one relationship in each heating unit 2, only those corresponding to one heating unit are shown in the drawing for convenience.

The electric circuit configuration of this electric cooker is as shown in FIG. 7 (only one heating unit is shown).Heating unit 2
The four halogen lamps 3 are connected in parallel to a power source 17, and the halogen lamps 3g are controlled to be turned on and off by a microcomputer 18.

The microcomputer 18 controls various electrical components included in the electric cooker, and receives signals from the thermostat 8 and various switches 12 to 15, and switches the light emitting diode 16 on and off according to the input signal. At the same time, one triac connected in series with three groups of halogen lamps is turned on and off via the drive circuit 20, thereby controlling the halogen lamps 3771 to be turned on and off. In this case, the microcomputer 18
operates to energize the halogen lamp 3 while the thermostat 8 is on, and the output (heat amount) of the halogen lamp 3 during the energization period is controlled by so-called phase control that controls the duty ratio of the triac 19. It has become. The output of this halogen lamp 3 is
Both switches 14 and 1 of pJ and input douvn J
5, and the set output can be switched by a signal from a thermostat 8. That is, after a predetermined time, in this embodiment, after the start of cooking, the microcomputer 18 changes the output of the halogen lamp 3 to its maximum output in the next on period, every time the thermostat 8 detects a predetermined temperature or higher and turns off. (2KW) of 596 (0,IKW)
It is programmed to gradually decrease. Therefore, the microcomputer 18 functions as an output control means for controlling the output of the halogen lamp 3.

Next, the operation of the above structure will be explained with reference to the time charts of FIGS. 1 and 2. The time charts in Figures 1 and 2 are based on the results of an experiment in which 2g of water was placed in a pot with good heat absorption and a pot with poor heat absorption. The surface temperature of the thermostat is the surface temperature of the outer tube 9a of the heat sensitive section 9.

First, to explain the case of a pot with good heat absorption rate in FIG.
vn Operate the J switch 15 to set the output of l\logen lamp 3.

Now, set the output of halogen lamp 3 to its maximum output (2KW)
Suppose you set it to . Then, the heat emitted from the halogen lamp 3 is transferred directly to the pot placed on the top plate 7 by radiation or by conduction via the top plate 7, heating the pot while increasing the temperature inside the heating unit 2. It also affects people rapidly. When the temperature inside the heating unit 2 reaches a predetermined temperature or higher, the thermostat 8 is turned off (at time T1 in FIG. 1), and the microcomputer 18 receives this off signal and operates to cut off the power to the halogen lamp 3. When the temperature inside the heating unit 2 drops to a certain temperature due to the power cut off of the halogen lamp 3, the thermostat 8 turns on (at time T2 in FIG. 1), and upon receiving this on signal, the microcomputer 18 turns on the halogen lamp 3. works. At this time, microcomputer 1
8 is the halogen lamp 3 whose output is 0°IK compared to the previous time.
By controlling the phase via the triac 19 so that WM is 1.9KW, the halogen lamp 3 is 2
It generates heat when the power is reduced from KW to 1.9KW. Although the temperature inside the heating unit 2 starts to rise again due to the re-energization of the halogen lamp 3, the output of the halogen lamp 3 is reduced by one step, so in the example of FIG. is almost in balance with the amount of heat absorbed by the pot etc. Therefore, after that, heating unit 2
The temperature inside the lamp no longer rises to the temperature at which the thermostat 8 turns off, and the halogen lamp 3 is continuously energized with an output of 1.9 KW. Then, after heating the cooking container for a desired time, the user operates the "off" switch 13, thereby finishing the cooking.

Next, the case of a pot with poor heat absorption rate will be explained with reference to FIG. 2. Assume that the output of the halogen lamp 3 is set to 2 KW and cooking is started in the same manner as described above. Then, the pot on the top plate 7 is heated, and the temperature inside the heating unit 2 also rises rapidly. When the temperature inside the heating unit 2 reaches a predetermined temperature, the thermostat 8 is turned off and the halogen lamp 3 is turned off. (at time T1 in Figure 2).

As a result, when the temperature inside the heating unit 2 drops to the desired level,
Since the thermostat 8 is turned on, the halogen lamp 3 is 0. Electricity is applied to generate heat at an output of 1.9 KW, which is a decrease in IKW (time T2 in FIG. 1). However, in the case of Fig. 2, since the heat absorption rate of the pot is poor, even if the output of the halogen lamp 3 is reduced to 1.9KW, the calorific value of the halogen lamp 3 is still absorbed by the pot, etc. Therefore, the humidity inside the heating unit 2 rises to the predetermined temperature again, and the thermostat 8 turns off by +Ij degrees (at T1 in FIG. 2), causing the halogen lamp 3 to turn off.
is cut off. As a result, the temperature inside the heating unit 2 decreases, and when the thermostat 8 is turned on again, the halogen lamp 3 is energized to generate heat at an output of 1.8 KW, which is 0° IKW lower than the previous time (at time T4 in Figure 2). .

In this way, each time the thermostat 8 is turned off, the output of the halogen lamp 3 is reduced to 0. The output of the halogen lamp 3 is gradually reduced by IKW, and finally the output of the halogen lamp 3 comes to be in balance with the amount of heat taken by the pot or the like. FIG. 2 shows an example in which when the output of the halogen lamp 3 is 1.6 KW, its calorific value is balanced with the calorific value of a pot or the like. When the output of the halogen lamp 3 becomes balanced with the amount of heat absorbed by the pot or the like, the thermostat 8 will no longer be turned off and the halogen lamp 3 will continue to be energized. Note that the output of the halogen lamp 3 is 1. ．． 6KW
However, if the calorific value exceeds the heat absorbed by the pot hat, the output of the halogen lamp 3 will further decrease to 0. It is reduced by IKW.

As described above, while the temperature inside the heating unit 2 is controlled by the thermostat 8 so as not to exceed the heat resistance limit of the halogen lamp 3, the output of the halogen lamp 3 is adjusted and cooking is performed. Then, after heating the cooking container for a desired time, the user operates the "off" switch 13, thereby finishing the cooking.

As described above, according to this embodiment, each time the thermostat 8 detects a predetermined temperature (turns off), the output of the halogen lamp 3 is decreased one step at a time, so that the output of the halogen lamp 3, that is, the amount of heat generated, ultimately decreases. The amount of heat is automatically adjusted so as to be in balance with the amount of heat absorbed by the pot etc., and thereafter the halogen lamp 3 is continuously energized. Moreover, until the output (calorific value) of the halogen lamp 3 becomes balanced with the amount of heat absorbed by the pot, etc., the halogen lamp 3 is turned on and off as the thermostat 8 turns on and off; The cycle becomes gradually longer because the output of the halogen lamp 3 gradually approaches the amount of heat absorbed by a pot or the like. As a result of the above, the number of times the halogen lamp 3 is turned on and off is much smaller than in the past, and the life of the halogen lamp 3 can be extended. Furthermore, since the time during which the halogen lamp 3 is continuously energized becomes longer, for example, the time required to heat water to 95° C. in FIGS. 1 and 2 and FIGS. 9 and 10 is In comparison, in the case of a pot with good heat absorption rate, it takes R11 compared to 593 seconds in the conventional case, and in this example it takes 585 seconds, and in the case of a pot with poor heat absorption rate, it takes 653 seconds in the conventional case. In this embodiment, the time is 647 seconds, and the output of the halogen lamp 3 is 0. Even if there is a situation where the IKW is reduced in increments, the pot can be heated well.

In the above embodiment, each time the thermostat 8 is turned off after the start of cooking, the output of the halogen lamp 3 is reduced one step at a time when electricity is turned on. The output of the halogen lamp may be kept constant regardless of whether the thermostat 8 is turned off, and the output of the halogen lamp 3 may be lowered by one step each time the thermostat 8 is turned off after 5 minutes of irradiation.

Furthermore, in the above embodiment, the halogen lamp 3 is cut off when the thermostat 8 is turned off.
As shown in Figure 8, the off JOJ of thermostat 8
During l1jJ, the output of the halogen lamp 3 may be reduced to approximately IKW. Even in this case, the number of times that the current value flowing through the halogen lamp 3 changes greatly can be reduced, and the life of the halogen lamp 3 can be extended.

[Effects of the Invention] As is clear from the above description, according to the electric cooker of the present invention, after a predetermined time, each time the temperature detection means detects that the ambient temperature of the lamp heater has become equal to or higher than a predetermined 1H degree. By gradually reducing the output of the lamp heater, the output of the lamp heater can be brought close to the amount of heat absorbed by the object to be heated, while preventing the ambient temperature of the lamp heater from exceeding the heat-resistant limit temperature of the lamp heater. This has the excellent effect of extending the life of the lamp heater by reducing the number of times the lamp heater is turned on and off or the number of large increases and decreases in the current of the lamp heater.

[Brief explanation of the drawing]

1 to 7 show an embodiment of the present invention,
Figure 1 is a time chart showing the temperature changes of each part in the case of a pot with good heat absorption rate, Figure 2 is a time chart showing the temperature changes of each part in the case of a pot with poor heat absorption rate, and Figure 3 is a time chart showing the temperature changes of each part in the case of a pot with poor heat absorption rate. 4 is an enlarged vertical sectional view of the heating unit; FIG. 5 is an enlarged perspective view of the heating unit with the top plate removed; FIG. 6 is a partially enlarged front view of the operation panel; The figure is an electric circuit configuration diagram, and FIG. 8 is a diagram corresponding to FIG. 2 showing another embodiment of the present invention, FIG. 9, and FIG.
FIG. 0 is a diagram corresponding to FIGS. 1 and 2 of a conventional electric cooking device. In the figure, 2 is a heating unit, 3 is a halogen lamp (lamp heater), 4 and 5 are upper and lower insulators, 7 is a top plate, 8 is a thermostat (temperature detection means), ] 8 is a microcomputer (output control means). Applicant Toshiba Corporation Toshiba Audio/Video Engineering Co., Ltd. Time - Figure 1 Time - Figure Figure Figure Figure Figure Figure

Claims (1)

[Claims] 1. A lamp heater is used as a heat source, the upper part of which is covered with a translucent top plate, and an object to be heated placed on the top plate is heated and cooked, and the ambient temperature of the lamp heater is An electric cooking device characterized in that it is provided with a temperature detection means for detecting the temperature, and an output control means for gradually decreasing the output of the lamp heater each time the temperature detection means detects a predetermined temperature or more after a predetermined time. vessel.