JPH01690A - Heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a heating device that requires balancing the calorific value of the heating heat sources when heating using multiple heating heat sources at the same time, such as an electric open oven or an open microwave oven. be.

Conventional technology In the case of a heating chamber, such as a toaster oven, bread is placed in the heating chamber and the bread is toasted by energizing heaters provided above and below the heating chamber.

In conventional toaster ovens of this type, the energization ratio between the upper heater and the lower heater was kept constant. Further, for this reason, it is necessary to set the heat storage amount 9 heat generation rise 9 distance to the food, etc. of the upper heater and the lower heater to be the same, respectively.

If this is not done, there will be problems such as the front side of the bread being toasted well but the back side being barely cooked.

Problems to be Solved by the Invention However, when the characteristics of the upper and lower heaters are different, or when the distance between the food and the heater (heat source) is different, it is possible to control the output of each heat source to control the front and back of the food. When firing, it becomes necessary to equalize the process. It is possible to control this by using a temperature sensing element such as a thermistor, but
This has disadvantages such as increased cost and the need for an element for each heat source.

Means for Solving the Problems The output of at least one of a plurality of heat sources, for example, an upper heater and a lower heater, is varied to at least two outputs, and while operating at the first higher output, a predetermined A control unit having an energy calculation means and an output determination means is provided so that a certain calculation value is obtained using the calculation formula and the output is changed to a second output when this value reaches a predetermined value. It is.

Further, 1. The energy calculation means is configured to calculate a calculation value using another calculation formula when the heat source is not performing a heating operation.

Function: Since the predetermined calculated value can roughly approximate the amount of heat given to the food, it is possible to balance the amount of heat supplied by the upper and lower heaters.

Example Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a sectional view of essential parts of an embodiment of a domestic open range using the present invention. In the figure, 1 is a heating chamber.

An upper heater 2 is provided at the upper part of the heating chamber, and is composed of a heating wire covered with quartz glass. 3 is a planar heater attached closely to the lower surface of the heating chamber, and is called the lower heater.

4 is a magnetron that can heat food by emitting radio waves into the heating chamber. Reference numeral 6 denotes a food placing table, which can be rotated by engaging with the shaft 7 of the turntable motor 6, which passes through the lower surface of the heating chamber and the center of the surface heater. Reference numeral 8 denotes a cooling fan, which cools the magnetron and other components (not shown) such as a high-voltage transformer and a control circuit.

With these configurations, the food 9 placed in the heating chamber can be heated in the oven by heating it using radio waves or by increasing the temperature inside the heating chamber using the upper heater 2 and the lower heater 3. can.

FIG. 4 shows an embodiment of the electronic circuit and control circuit of the home open range according to the embodiment of the present invention shown in FIG. In the same figure, 10 is an outlet for commercial power supply,
11 is a door switch that opens and closes in conjunction with the door of the heating chamber; one of them 12 is a microcomputer 13;
has been entered.

2 and 3 are the above-mentioned upper and lower heaters, respectively. 8 is a cooling fan, 1.4 is a high voltage power supply section,
Supply power to magnetron 4.

R-A1 to R-Aro are each relays, and their contacts are opened and closed by a control circuit. 16 is a control circuit and RA1
~R This is a low voltage power supply that supplies the operating power for Allo. The microcomputer 13 stores a program that executes an embodiment of a control sequence according to the present invention, which will be described later. Further, as an input, a clock signal for generating a timing signal synchronized with the commercial power supply indicated by the square is input. Also, if you input the type of heating sequence, such as "toaster", "pizza", "microwave heating", etc., it will resonate with "heating time" and so on.

A setting means 17 consisting of an operation switch for instructing to start and stop heating is connected. -18 is a display means that displays the type of heating sequence that has been set, the heating time or remaining heating time, and the time. 19 is the relay RA1~
This is a driving IC that drives the R-A5. , in addition to these,
- It consists of a buzzer (not shown) that sounds in response to the operation of the set child plant.

FIG. 1 shows an embodiment of a block diagram of a control section in an embodiment of the present invention. This is configured as a program in the microcomputer 13 shown in FIG. 3 mentioned above.

First, the setting section 28 gives the heating sequence and heating time set by the setting means to the operation command section 20, and the operation command section 2o starts the heating operation based on the door signal, the setting contents, heating start input, etc.

Instructs to suspend, terminate, etc.

The time measuring means 21 receives the clock signal 1 shown in FIG.
6 is used as a reference pulse generator 22, a clock pulse is inputted, and a certain period of time, for example, 1 second or 1 minute, is measured and a time signal is given to each block. The energy calculation means 23 is a means for constantly calculating and storing the amount of energy supplied to the heater according to a procedure to be explained in detail later, and is constituted by a memory and a program in a microcomputer. Furthermore, the end point energy storage means 24 calculates the energy calculated by the energy calculation means 23 at the end of the heating time, such as when the heating time ends, when the user cancels the operation, or when the user opens the door during heating. This is a memory for storing the amount of energy.

The output determining means 26 combines signals from the heating sequence, the current energy amount from the energy calculation means 23, the end point energy storage means, the time measuring means, etc., and determines the heat source ( This is a means for determining the output of the heater. The output of this is passed through a drive means 26, such as the drive IC 19 shown in FIG. 3, to a heat source 27, such as a heater.

The first feature of the configuration of the present invention is that there is no temperature measuring means such as a thermistor. Therefore, the control system does not include feedback from the heat source 27 or the heating chamber.

The second feature is the calculation means 2 that constantly calculates the amount of energy.
Third, it has an output determining means for finally determining the output of the heat source.

Now, in order to explain in detail the operation of each of the blocks mentioned above, one embodiment of the heating sequence according to the present invention will be explained using FIG. 2.

FIG. 2) is a diagram showing an example of the relationship between the temperature of a predetermined portion of the heating chamber heated by the heater and time, as well as the calculation of the amount of energy according to the present invention.

Heater (heat source output) at a constant maximum output, e.g. 1k
When heating starts at w, until time t.

As shown by curve a, the temperature rises exponentially with a delay element, and after that, the temperature continues to rise as shown by the dotted line until the equilibrium temperature is reached. It can be easily verified through experiments that this curve has a nearly fixed rise depending on the amount and temperature of the heat capacity 9 food in the heating chamber. In actual temperature control, it is necessary to maintain a constant temperature at a predetermined set temperature, so in the present invention, the heat source output is changed from Pl to P
Reduce to 2. This makes the temperature Y like C.

It can be balanced and kept constant.

How much these outputs should be selected can be determined through experimentation. When the heating ends at time t2, the temperature decreases exponentially as d.

The advantage of the present invention is that by simulating such physical phenomena using theoretical analytical formulas, it is possible to perform the necessary temperature control without configuring a feedback loop using a temperature sensor. This is the basic idea.

In other words, for simplicity, the rising curve a from the start of heating is expressed as y = (YMt −Y□)・t/11+Y0...
...(1) Assuming that the straight line e is an approximate curve, when the set temperature is yn, the time t8 for switching the heat source from the highest output P1 to the next low output P2 is calculated using the above approximate formula. It can be obtained from t,=(yn-Yo)・t1/(YM-Yo).

As described above, the present invention has the advantage that the time for switching the output of the heat source can be immediately determined using the arithmetic expression shown in 1 above as an example. This eliminates the need for elements such as thermistors.

As described above, if the lower heater is controlled, the amount of heat supplied to the food can be controlled because the food is closer to the lower heater. Of course, it is obvious that more fine control can be achieved if the upper heater and lower heater are each independently calculated and controlled.

There are two problems here.

One problem is that when residual heat remains in the heating chamber, such as during the first, second, etc., it is necessary to change the heating time of the heat source depending on the downtime.

For this reason, one embodiment of the present invention has the feature of calculating and storing the decrease in temperature even when the heat source is not in operation.

FIG. 2(B) shows an example of such a case.

This is an example in which heating is performed by the heat source P until time t3, heating is stopped for a period from time t3 to t4, and heating is performed again at 161 after t4. In each case, the temperature rises along the curve f, and when it reaches Y3, it then decreases according to the curve q, and when it decreases at Y41, it rises according to the curve. By applying an experimentally determined approximate curve to each curve, it is possible to reliably control the temperature to a predetermined temperature.

The second problem is that if the type or amount of food changes, the above-mentioned approximation formula must be changed.

Therefore, in one embodiment of the present invention, such a problem is solved by dividing the heating sequences into groups in which such differences do not appear much when selecting heating sequences. For example, a toaster.

If you classify food into categories like pizza, you won't need to think about the differences in the amount of food.

In the above explanation, the explanation focused on temperature change, but since temperature is not always the only factor, the following explanation uses the word energy.

FIG. 5 shows yet another embodiment. In FIG. 5, the word "temperature" used in the above explanation has been replaced with the word "energy", and what was shown as various curves has been approximated with straight lines.

First, until time t1, heating is performed at the maximum output of the heat source P. At this time, the energy calculation means uses the calculation formula Y==A-t+Y0mif1(t) as the current energy calculation amount Y, and calculates (
(t is time, A and B are predetermined constants), and at time t1 when Y reaches a predetermined maximum value YM, the heat source output is reduced to P2.

Then, at t2, the time set for heating has ended, so heating is ended. When the energy calculation amount Y reaches YM, the heating output is reduced, so the calculation amount Y also decreases to Y.
, is maintained. Then, after heating is completed, a certain period of time T
Up to 1, the energy calculation amount Y remains YM, but
From then on until T2, the first subtraction formula (il(T) is used, and after T2, the energy calculation amount is calculated using the second subtraction formula q2 (T).

These approximate expressions can approximate the temperature change explained using FIG.

FIG. 6 shows another more advanced embodiment.

FIG. 6 shows that the first heating was started in the same manner as in FIG. 6 and ended at time t3.

At this time, it is assumed that the energy calculation amount y is calculated by the calculation formula y=f1(t), and the value is, for example, Yl. After that, it was left as it was until time t4, so as shown in FIG. 6, the energy calculation amount Y was reduced to Y2. If a heating command is given at this point, heating is performed at the heating output P1, as in the beginning. Similarly, the energy calculation amount y is y =
It is calculated by the function of fl(t) and increases, but after this value becomes equal to the energy calculation amount Y1 at the end point, the second increasing function y = f2(t) is used. The device is characterized in that it calculates the amount of energy calculation and operates with the same heating output until the value reaches a certain predetermined value YM.

The reason for introducing the second increasing function f2 is that, as explained in the principle of FIG. 2, actual physical phenomena change exponentially with a delay element, whereas in this example Since formulas are used, errors occur. A second increasing function is introduced to correct this error.

Effect of the invention As mentioned above, the following effects are achieved by the above configuration.

(1) Since no temperature sensing element such as a thermistor is used, the structure is simple and inexpensive.

(Kon) Since the amount of energy stored through past heating is estimated, accurate control can be performed. (2) It can be performed using only time measurement and a simple calculation formula.

(4) If there are multiple heaters such as an upper heater and a lower heater, the heat distribution can be made uniform by individually controlling the output of each heater.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the control section of a heater in an embodiment of the present invention, Figs. 2 (A) and (B) are explanatory diagrams showing the relationship between temperature and output, respectively, and Fig. 3 is the main part of the same. A sectional view, FIG. 4, and a control circuit diagram of the same device, FIG. 6. FIG. 6 is an explanatory diagram showing the calculation amount calculated by the energy calculation means of the device. Pl, P2...Output of heat source (for example, lower heater), 2...Upper heater, 3...Lower heater, 13...Microcomputer , Y.M.
......A predetermined constant value that indicates the upper limit of the calculated value. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 111 Upper C-tater 3--T heater 10--Z,-! N! 4-line pressure t31 t6--20・day+st

Claims (2)

[Claims] (1) A heating chamber, a first heat source provided in the heating chamber, a second heat source that also heats the heating chamber, a setting unit that sets the heating operation of the heater, and a time that measures the reference time. a measuring means; an operation command section that determines the start and end of a heating operation based on a signal from the setting section; and at least one of the first and second heat sources during the heating operation and during the heating stop. energy calculation means for calculating a predetermined calculation value for one heat source according to a predetermined calculation formula, and when the calculation value reaches a predetermined value during heating operation, the first or second 1. A heater comprising output determining means for reducing or cutting off the output of any one of the heat sources. (2) End-time energy storage means is provided to store the calculated value calculated by the energy calculation means at the end of heating, and the energy calculation means stores at least two calculation formulas f_1(t) during heating. f_2(t)
and compares it with the value stored in the end point energy storage means. While the calculated value is small, f_1(t) of the calculation formula is used, and after the calculated value becomes large, f_1(t) is used. The heater according to claim 1, characterized in that the arithmetic expression f_2(t) of 2 is used.