JP2523749B2 - Heating device - Google Patents

Description

TECHNICAL FIELD The present invention utilizes the level detected by a sensor for controlling the temperature inside the refrigerator, and turns on and off a heat source by a microcomputer, so that the temperature inside the refrigerator exceeds a predetermined temperature. The present invention relates to a heating cooker for heating objects to be heated at a predetermined temperature to finish the objects to be heated, especially cakes, cookies, and the like having difficult temperature control in more optimal states. .

2. Description of the Related Art In recent years, with the spread of cookers such as open ranges, making cakes using cookies, cookies, puffs and ovens is rapidly increasing at home. In addition, due to the recent trend toward gourmet foods, it has become important to improve the quality of food and speed up cooking time.

However, the cooking of these cakes, cookies, puffs, etc. is sensitive to the heating temperature, and when the temperature exceeds the predetermined temperature for baking (hereinafter referred to as overshoot), the quality of preparation tends to be extremely poor. . This is because if you overshoot, you would normally bake at a temperature higher than the optimum baking temperature of the food, so the surface of the food will be baked first and the moisture inside will not escape and it will be in a raw state. Because.

In order to prevent this overshoot, conventionally, before placing the object to be heated in the heating chamber, it was general to perform air-baking until the temperature inside the heating chamber reached the baking temperature (hereinafter, this is preheated). Say).

However, preheating is time consuming and wastes energy. Further, even if preheating is performed, if it takes time to put the workpiece in the heating chamber, there is a problem that the temperature in the heating chamber decreases and an overshoot occurs.

As a countermeasure against this, a method of eliminating overshoot without preheating has been proposed. This is in addition to the first sensor that detects the temperature inside the conventional chamber and controls the ON / OFF of the heater, and is installed near the Peter, and the second sensor that detects the temperature of the heater itself is installed. The overshoot is eliminated by covering the delay in the thermal response of the conventional sensor.

Problems to be Solved by the Invention However, this configuration has the following problems. First,
Since this second sensor must be installed in the vicinity of the heater, it must have excellent high temperature characteristics and is very expensive. Next, the second sensor must be in complete contact with the heater, which complicates the mounting structure and reduces workability. Further, it is easily affected by wind from the outside and heat of a lamp or the like for illuminating the inside of the refrigerator. Moreover, although this second thermistor has excellent high-temperature characteristics, it is not suitable for controlling the temperature inside the refrigerator, and it is necessary to use two thermistors together with the conventional one. ing.

The present invention solves such a conventional problem, and uses a sensor used in a conventional cooking device, and changes the resistance of the sensor depending on the temperature into a voltage level ( (Hereinafter referred to as the sensor level) and the level corresponding to the set temperature, that is, the level at which the heat source is turned on when the sensor level is below this level, and the heat source is turned off when it exceeds this level (hereinafter referred to as the temperature control level). With or without preheating, that is, at various starting temperatures, overshoot is eliminated and excellent cooking performance is achieved even under various use conditions such as opening the door during cooking and interrupting cooking during operation. The present invention provides a heating cooker that has and is inexpensive.

Means for Solving the Problems The heating cooker of the present invention has the following configuration. That is, an operation panel provided on the front surface of the main body for setting the type of heating, heating conditions, etc. and a display device for displaying these, a heating chamber for storing an object to be heated in the main body, and an inside of the heating chamber. A heat source for heating the object to be heated, a sensor for detecting the temperature inside the heating chamber, and a control unit for controlling the temperature inside the chamber according to the level detected by the sensor, the control unit after the start of cooking A value obtained by multiplying the lowest point level l ₀ detected by the sensor by a value K obtained by subtracting the level l ₀ from the temperature control level L corresponding to the set temperature of the sensor, and a food-specific coefficient K determined by the food. When the level 1 obtained by addition is reached, the heat source is paused for a certain period of time, and after the pause, the control before the pause is continued to perform control.

2. The heating device according to claim 1, wherein the control unit is configured to, after the heat source is stopped for a certain period of time when the level becomes l, forcibly turn on the heat source for a certain period of time.

In addition, the control unit turns off the heat source according to the coefficient (0 <Kn <1).
Is provided at least twice.

Further, the control unit is configured such that turning off of the heat source by the coefficient K is finished when the level of the sensor reaches the temperature control level, and then the temperature inside the refrigerator is controlled by the temperature control level L of the sensor.

Further, the control unit is configured to detect the level l ₀ again when the cooking is interrupted by opening and canceling the door after starting the cooking, or when the set temperature is changed and the cooking is restarted.

Further, when the detection level of the sensor is equal to or higher than the temperature control level L after the start of cooking, the control unit is configured to detect the level ₁₀ after the heat source is turned on.

Further, the control unit is configured to use the control in a certain range within the settable temperature range.

Action The heating cooker of the present invention utilizes the temperature control level L of the atmosphere thermistor and the lowest point level l ₀ after the start, and ln = l ₀ + Kn (L-l ₀ ). Is calculated and when it reaches that level, the heat source is turned off for a certain period of time
By carrying out the process until the temperature control level L is reached, it is possible to eliminate the overshoot of the central temperature in the refrigerator and to provide the optimum food quality.

Example Hereinafter, a heating cooker according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a main body of a heating device showing an embodiment of the present invention. A door 3 is provided in the opening 2 of the main body 1 so as to be openable and closable, and an operation panel 4 is provided. On the operation panel 4, as an input means, an oven key 5 for heating and cooking, a temperature setting key 6 for setting a heating temperature, a timer volume 7 for setting a heating time, a cooking start key 8,
A cancel key 8'for clearing the input data is provided. Reference numeral 9 denotes a display window for displaying the data set via the input means.

FIG. 2 is a block diagram showing the system configuration of the heating device. The operation panel 4 includes a control circuit 10 composed of a microcomputer or the like. 11 is a heating chamber, motor 12
A placing tray 14 is placed on a saucer table 13 which is rotationally driven by. A heat source, which is a flat heater 15, is attached to the upper and lower portions of the heating chamber 11 to heat an object to be heated 16.

Further, an atmosphere thermistor 17 serving as a sensor for detecting the temperature inside the chamber is arranged on the side surface of the heating chamber 11, and when the temperature inside the chamber changes, the resistance of the atmosphere thermistor 17 changes. When this change is transmitted to the control circuit 10 and reaches the set temperature input from the oven key 5 and the set temperature key 6 of the operation panel 4, the flat heater 15 is turned on and off to control the temperature inside the chamber to the set temperature. It The atmosphere thermistor 17 is covered with a cover 18 to protect it from dirt and damage.

First, how the calculation formula used in the present invention is derived will be described.

FIG. 3 is a block diagram of the heating device in which the experiment was conducted. An object 16 to be heated is placed in the heating chamber 11, and a thermocouple 19 is installed above the object 16 so that the temperature inside the refrigerator can be measured. The output control means 20 controls the flat heater 15 of the heat source according to the temperature measured by the thermocouple 19. Further, the thermistor 17 continuously displays the sensor level on the display means 21.

FIG. 4 is a chart diagram when a cake at 150 ° C. was cooked. (A) shows the time change of the internal temperature measured by the thermocouple 19. (B) shows the output state of the flat heater 15 of the heat source. (C) shows the time change of the sensor level read by the display means 21. A, B, and C in each drawing show the difference due to the difference in the starting temperature in the heating chamber 11. A corresponds to normal heating without preheating when the heating chamber 11 is cold, and the temperature inside the heating chamber 11 increases in the order of B and C.

As shown in FIG. 4 (a), since the thermocouple 19 measures and controls the vicinity of the object 16 to be heated, ideal control can be performed without overshooting at any starting temperature. It is a graph in which the sensor level at that time is shown by (C).
Although the control level L is not reached at the broken line portion, the flat heater 15 of the heat source is off.

On the contrary, before the sensor level reaches the temperature control level L, the flat heater 15 of the heat source is turned off in the same manner as (C).
If it is possible to perform such control, ideal control without overshoot as in (a) should be possible.
From the graph in (c), it can be seen that the sensor level ln (l ₁ , l ₂ , l ₃ ) that turns off the heat source has regularity. That is, the line connecting each of l ₁ , l ₂ and l ₃ when the starting temperature is changed like A, B and C is represented by a linear function. FIG. 4 is a characteristic diagram in the case of cake cooking, but similar results can be obtained with a menu such as cookies and puffs. Was derived from the graph is the equation _{ln = l 0 + Kn · (} L-l 0) (l 0: the lowest point level after cooking start, L: temperature control level, K: constant). For example, in the state of A, the levels of l ₁ , l ₂ and l ₃ obtained by calculating the above equation from the initial level l ₀ are values that can be approximated to ideal values, and the levels of l ₁ , l ₂ and l ₃ are When it reaches, the heat source is turned off for t ₁ , t ₂ , and t ₃ seconds, and a graph without overshoot is obtained as shown in (a). Similar experiments were performed on B and C, but overshoot did not occur as in A. In addition, at starting temperatures other than A, B and C, ln (l ₁ , l obtained by the above calculation formula ln = l ₀ + Kn · (L−l ₀ ).
₂ and l ₃ ) are all on the straight line of the linear function. That is, even if the starting temperatures are different, it becomes a straight line by connecting, for example, the level l ₁ corresponding to the respective temperatures. Therefore, the point where the power supply to the heating source is stopped first is a straight line (linear function)
The heating source may be controlled so as to be arranged at the position represented by. The slope of this straight line is set so that it becomes gentler as the turns overlap.

Here, if n is large, finer control is possible, but OF
Since the number of times of F increases, cooking time becomes longer. Although there was a difference depending on the type of heating cooker, the cooking time of about 3 to 5 times was not long and was in the best condition. The constant K is the heating chamber
Although it is a constant determined by the heated object 16 placed in 11,
For automatic cooking, it is better to have a constant K for each menu, such as cookies, cakes, and puffs, for more accurate control, but in a normal manual cooker, it is shared in each temperature range. Also gives good results.

FIG. 5 is a chart showing a control method in the case of setting 150 ° C. according to the present invention. A figure shows the time change of the atmosphere thermistor level, and B figure shows the output state of the heat source.
Fig. C shows the time variation of the temperature inside the refrigerator.

The control circuit 9 always reads the sensor level of the in-compartment temperature detected by the atmosphere thermistor 17 after the start of cooking. Then, the sensor level l ₀ at the time when the sensor level becomes the lowest point is stored, and ln = l ₀ + Kn · (L−
l ₀ ) is calculated (n = 1,2,3).

Where l ₀ : lowest sensor level after start L: temperature control level of atmosphere thermistor Kn: coefficient determined by food When the ln level obtained from the above formula is reached, t _n
Seconds Turn off the heat source. In this example, K _n is
Since three are set, K ₁ = 0.6, K ₂ = 0.84, K ₃ = 0.99, l
The flat heater 15 of the heat source is turned off for three times of ₁ , l ₂ , l ₃ respectively t ₁ = 90 seconds, t ₂ = 90 seconds, t ₃ = 90 seconds.

However, when the level of the atmosphere thermistor 17 reaches the temperature control level L, the control is immediately stopped and the control of the conventional atmosphere thermistor 17 is started.

However, when the cooking start temperature is high immediately after preheating or in continuous use, that is, when l ₀ is close to L within the range of l ₀ <L, l ₁ , l ₂ , obtained by the calculation formula l ₃ levels are close together. For example, L = 100, K ₁ = 0.7, K ₂ = 0.8, K ₃ = 0.9
In case of l ₀ = 90, l ₁ = 97, l ₂ = 98, l ₃ = 99 and l ₁
The level of l ₂ is reached during the OFF of t ₁ seconds, and the OFF is continuously applied for (t ₁ + t ₂ ) seconds, which causes an overshoot at l ₃ . In order to prevent this, the heat source is forcibly turned on for t ′ seconds after turning OFF.
I will let you N. According to experiments, this problem is solved by turning on for t '= 30 seconds.

In addition, in the case of continuous use, it is 2 more than the first cooking temperature.
When the cooking temperature for the second time is low, l ₀ ≧ L and the sensor level is already above the temperature control level, so the heat source has been off since the start. In such a case, if the control is stopped when the temperature control level is reached as shown in FIG. 4, an overshoot occurs as shown in FIG. 6, so if l ₀ ≧ L, then l ₀ <L The control is started from the point when. By doing so, overshoot does not occur as shown in FIG.

In addition, after the start of cooking, if the door 3 is canceled by opening or canceling it, the operation panel 4, the temperature setting key 6
When the set temperature is changed by, instead of continuing the control when starting cooking again, the same as the start when the temperature in the heating chamber 11 is high, so the lowest point level l ₀ is detected after restarting. Then, the above control is repeated.

By performing the control as described above, there is preheating, no preheating, continuous use, and even if the door 3 is opened halfway, the cancel key 8 is pressed, or the operation is interrupted due to a user's operation error It is possible to eliminate the occurrence of overshoot and to provide the optimum food product finish.

Next, regarding the temperature range in which the above-mentioned control is carried out, it should be performed in all temperature ranges of the heating cooker, but the control circuit 9
There is also a problem with the microcomputer's capacity, and there are also menus that do not affect the performance even if there is overshoot, so the temperature range of sweets cakes, cookies, puffs, etc. that are particularly affected by overshoot 150- If it is limited to 180 ℃, the capacity of the microcomputer will be reduced.

Further, in the embodiment of the present invention, the heat source which is the flat heater is used, but the present invention can be applied to any heating device such as one using a sheath heater and one using a hot air circulation system.

Next, the control method of the present invention will be described with reference to the flowchart shown in FIG. Oven key 5 on the operation panel 4,
Set time T by temperature setting key 6 and timer volume 7.
Input, the time t is reset when the set time T is input, the door 3 is closed, the cooking start key is input and cooking is started. If the set temperature is 150 ° C ≤ set temperature ≤ 180 ° C For example, the control of the present invention is started. Simultaneously with the start, the sensor level 1 of the thermistor is read every 1 second. If the sensor level 1 is higher than the temperature control level L, the heater does not turn on until 1 <L, the heater turns on when 1 <L. Then, the level one second after that time is compared with the previous level, and if the level one second later becomes large, the previous level is set to l _0. If l ₀ is detected, ln = l _{From 0} + Kn- (L-l ₀ ), l ₁
Calculate the level, when it reaches the l ₁ level, turn off the heater for t ₁ second, and after t ₁ second, forcibly turn on the heater for 30 seconds. Repeat this 3 times. When it comes, cooking is finished. When the temperature is not 150 ℃ ≤ set temperature ≤ 180 ℃, it always counts up during control and returns if the door is opened and the cancel key is pressed again. Also, if the thermistor level is l ≧
When it goes to L, the conventional control is performed. This is always done (however, if 1> L after the start of cooking, it will not be done).

Effects of the Invention From the above description, according to the present invention, the following effects can be obtained.

(1) The feature is that the heat source is turned on and off by the microcomputer by using the detection level of the sensor that controls the internal temperature, so not only the overshoot is eliminated but also the internal temperature can be controlled freely. You can For example, it is possible to control at a low temperature in the first half of cooking and control at a high temperature in the latter half. Therefore, not only the conventional microwave oven but also the automatic cooking device can be finely controlled, which is very effective.

(2) When the lowest level l ₀ is close to the temperature control level L by turning on the heat source for a certain period of time after stopping the heat source for a certain period of time at the level 1 Can prevent overshoot due to long OFF time.

(3) Since the coefficient K is provided twice or more, finer control can be performed.

(4) After the sensor level reaches the temperature control level, the internal temperature is controlled by the sensor temperature control level, so that the final heating can be accurately performed.

(5) Even if the cooking is restarted due to the interruption of the cooking or the change of the set temperature, the sensor level l ₀ is detected again, so that the overshoot does not occur.

(6) When the above detection level temperature control level of the cooking start time of the sensor, since the heat source is configured to detect a level l ₀ from ON, and does not overshoot.

(7) The capacity of the microcomputer can be reduced because the control unit controls the heating heat source only in the type or operating temperature range in which the overshoot affects cooking.

(8) Since the temperature can be detected and the heating source can be controlled only by the conventional atmosphere thermistor, the structure can be inexpensive and simple.

[Brief description of drawings]

FIG. 1 is a perspective view of a main body showing an embodiment of the present invention, FIG. 2 is a configuration diagram showing the system configuration, and FIG. 3 is a block diagram showing a system configuration of an experiment conducted to derive a calculation formula.
FIG. 4 is a time chart showing an output state of the sensor level internal temperature / heat source, and FIG. 5 is a time chart showing an output state of the sensor level internal temperature / heat source of the heating apparatus according to the embodiment of the present invention. 6 is a time chart showing the internal temperature of the apparatus, FIG. 7 is a time chart showing the internal temperature of the apparatus, and FIG. 8 is a flowchart of the apparatus. 1 ... Main body, 4 ... Operation panel, 5 ... Oven key,
6 ... Temperature setting key, 10 ... Control circuit, 11 ... Heating chamber,
16 …… Heating object, 17 …… Atmosphere thermistor.

Claims (7)

(57) [Claims] 1. An operation panel provided on a front surface of a main body, which has input means for setting types of heating, heating conditions and the like and a display device for displaying the input means, and a heating chamber for accommodating an object to be heated in the main body. A heat source for heating an object to be heated in the heating chamber, and a sensor for detecting the temperature inside the heating chamber,
A control unit for controlling the temperature inside the refrigerator according to the level detected by the sensor, and the control unit controls the temperature corresponding to the set temperature of the sensor to the lowest level l ₀ detected by the sensor after cooking is started. When the level 1 obtained by adding a value obtained by multiplying the value obtained by subtracting the level l ₀ from the control level L by a food-specific coefficient K determined by the food is stopped for a certain period of time, the heat source is stopped for a certain period of time, and after the stop, A heating device configured to continue the control before suspension. 2. The control unit forcibly turns on the heat source for a certain period of time after suspending the heat source for a certain period of time when the level becomes 1 level.
The heating device according to claim 1, wherein the heating device is configured to perform. 3. The control unit is configured to turn off the heat source by a coefficient K (0 <Kn <1) at least twice.
A heating device as described. 4. The control unit ends the turning off of the heat source by the coefficient K when the level of the sensor reaches the temperature control level L, and thereafter controls the temperature inside the refrigerator by the temperature control level L of the sensor. The heating device according to claim 1, which is configured. 5. The control unit is configured to detect the level l ₀ again when the cooking is interrupted by opening and canceling the door after starting the cooking, or when the set temperature is changed and the cooking is restarted. The heating device described. 6. The heating device according to claim 1, wherein the control unit is configured to detect the level l ₀ after the heat source is turned on when the detection level of the sensor is equal to or higher than the temperature control level L after the start of cooking. 7. The heating device according to claim 1, wherein the control unit is configured to use the control in a certain range within the settable temperature range.