JPS6053256B2 - Oven temperature control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention provides an output from a temperature setting circuit including a variable resistor for setting indoor temperature and an output from a temperature detecting circuit including a temperature sensitive resistance element for detecting indoor temperature. In comparison, with respect to an open temperature control circuit controlling a heat source for indoor temperature control, in particular about 12 (f
It pertains to normal cooking at a high temperature of C to 25Crc and yeast cooking at about 3σC.

Same Prior Art In this type of temperature control circuit, when the configuration of the temperature detection circuit 1' is as shown in FIG. 5, the temperature vs. potential output characteristic is As shown in Figure 4, approximately 12 (auto) ~ 3
At 00'C, the slope is steep and there is little change in indoor temperature with respect to potential changes, so accurate temperature control is possible; As a result, accurate temperature control has become difficult due to errors in circuit constants, errors in temperature characteristics, etc.

In order to deal with this deficiency, the inventors of the present application have developed a first circuit that has a steep slope portion corresponding to the normal cooking temperature so that the output characteristics of the temperature detection circuit are changed between the normal cooking setting and the yeast cooking setting of the room temperature.
By switching between the temperature versus potential output characteristic and the second temperature versus potential output characteristic having a steep slope corresponding to the yeast cooking temperature using a switching means, accurate cooking can be achieved not only during normal cooking settings but also during yeast cooking settings. Invented a technology that allows temperature control.

However, in a configuration that simply switches the output characteristics of the temperature detection circuit, if the temperature setting circuit is set to the yeast cooking temperature, but the output characteristics switching means does not operate normally and the output characteristics do not change, the indoor There is a problem in that the temperature becomes unsuitable for yeast cooking and the yeast bacteria die.

Object of the Invention In view of the above-mentioned problems, the present invention enables accurate temperature control not only during the normal cooking setting but also during the yeast cooking setting, and also provides a method in the event that the output characteristic switching means of the temperature detection circuit fails. But the purpose is to not kill the yeast.

Country Structure of the Invention The structure of the present invention compares the output of a temperature setting circuit including a variable resistor for indoor temperature setting with the output of a temperature detection circuit including a temperature sensitive resistance element for detecting indoor temperature. In a device that controls a heat source, the output characteristic of the temperature detection circuit is changed to a first temperature-to-potential output characteristic having a steep slope portion corresponding to the normal cooking temperature when the room temperature is set to normal cooking temperature and when the yeast temperature setting is set. a first switching means for switching to a second temperature-to-potential output characteristic having a steep slope portion in accordance with the yeast cooking temperature; and a second switching means for changing the output of the temperature setting circuit stepwise toward a lower temperature side when setting the yeast preparation. The present invention is characterized by comprising a switching means.

According to such a configuration, when yeast adjustment is set, the output characteristic of the temperature detection circuit is switched to the second temperature vs. potential output characteristic by the first switching means, and the temperature is controlled using the steep portion of the potential/temperature gradient, thereby achieving accurate temperature control. Since temperature control is possible and the output of the temperature setting circuit is changed stepwise at the same time, the first
Even if the switching means fails and the output characteristics of the temperature detection circuit are not switched, the room temperature does not become high, and the yeast can be prevented from dying. (E) Example An example of the present invention will be explained regarding gas opening.

In Figures 1 to 4, 1 indicates a vertical opening door 2 at the front opening.
A cooking chamber 3 is partitioned at the rear of the cooking chamber 1 by a partition plate 6 having an inlet 4 and an outlet 5, and is equipped with a centrifugal fan 8 which is rotationally driven by a motor 7. The chamber 9 has a gas burner 13 as a heating means that communicates with the cooking chamber 1 through a hot air passage 10 and an induction port 11 defined below the cooking chamber 1 and whose fuel supply is controlled by a solenoid valve 12. In the combustion chamber, as the fan 8 rotates, air in the chamber 1 is sucked into the compartment 3 through the suction port 4 and then blown out into the chamber 1 through the blowout port 5, forced to circulate inside the chamber 1, and then Due to the attraction effect of the airflow from the The hot combustion air from the gas burner 13 is introduced into the chamber 1 through the combustion chamber 9, the hot air passage 10, and the induction port 11, and as this hot air circulates within the chamber, the food to be cooked in the cooking chamber 1 is heated and cooked. . Note that a part of the air in the chamber 1 is continuously exhausted from an exhaust port 14 provided above the compartment 3. The temperature inside the cooking chamber 1 is set by operating the temperature setting variable resistance knob 16 provided on the front surface 15 of the main body, and by detecting this set temperature and the exhaust temperature of the exhaust port 14, the temperature inside the cooking chamber 1 is set. The temperature detected by the temperature-sensitive resistance element Rt that detects the internal temperature is compared with the temperature detected by the temperature-sensitive resistance element Rt in the control circuit shown in FIG. 3, and is maintained at a constant value by controlling the solenoid valve 12 ON-OFF.

The control circuit shown in FIG. 3 will be explained in detail below. A is a temperature detection circuit that includes a temperature-sensitive resistance element Rt made of the above-mentioned negative characteristic thermistor, and whose output terminal A1 is connected to the negative input terminal of the first comparator CPl via a resistor R9, and a changeover switch as a first switching means. - By switching the SW, the output characteristic from the output terminal A1 is switched to the first temperature versus potential characteristic (hereinafter referred to as the first characteristic) P1 and the second temperature versus potential characteristic (hereinafter referred to as the second characteristic) P2 shown in FIG. .

Its specific configuration is fixed resistors Rl, R2, R4, semi-fixed resistor R5, temperature sensitive resistance element Rtl single pole double throw changeover switch SW
By switching switch SW to high temperature side contact h, resistor R2 is connected in parallel to element Rt, resistor R1 and resistor R4 are connected in series to this parallel circuit, and conversely switching to low temperature side contact 1. A resistor R5 is connected in series to the element Rt, and a resistor R2 and a resistor R4 are connected to this series circuit.
series circuits are connected in parallel, and a resistor R1 is connected in series to this parallel circuit. And these resistance values are R1=330
Ω, R2=39KΩ, R4=Si? Ω, R5=109KΩ
And the resistance value of 1-1 element Rt is Ra-Exp(B×(--))
TTaRa=葎Ω, Ta=200℃,
The first characteristic P1 and the second characteristic P2 are obtained by setting B=5000 and the power supply voltage to 12.times.1.

To set these resistance values, first determine the values of the resistors R2 and R4 so as to obtain the first characteristic P1, and set the detected temperature 120C or higher of the rth characteristic P1 as the steep slope part Pla, and set the detected temperature 100C or higher as the steep slope part Pla.
℃ or below is defined as a gentle slope part Plb, this steep slope part Pl
The second characteristic P2 is a characteristic in which a is moved to the low temperature side.
This is done by determining the resistor R5 so as to obtain .
Note that the resistor R1 is provided to prevent the input voltage of the comparator CPl from exceeding an upper limit value determined by the characteristics of the comparator, and its value is set low. Also, by making the resistor R5 a semi-fixed resistor, the temperature at 200℃? It is possible to absorb variations in the characteristics of the high-temperature temperature-sensitive resistance element Rt manufactured with a target of Ω at around 25°C. B is a temperature setting circuit made up of a fixed resistor R6, a variable resistor RV for temperature setting, fixed resistors R8l and R82 connected in series, and a sliding terminal 17 provided on the knob 16 of the variable resistor RV is used as an output terminal via a resistor RlO. is connected to the positive input terminal of the comparator CPl, and the knob 1 is connected to the positive input terminal of the comparator CPl.
A second resistor R8l is short-circuited when R6 is slid to a position away from the low-temperature end of the normal cooking temperature range of 120C to 250C.
By providing the variable resistor RV with a shorting piece 18 as a switching means, it is possible to obtain the set output characteristic Q shown in FIG. 4 in which the output decreases in a stepwise manner when setting the yeast adjustment.

This set output characteristic Q has a differential characteristic due to the feedback resistor Rll connecting the output terminal and the positive input terminal of the comparator CPl. Further, the shorting of the resistor R8l and the switching of the changeover switch SW to the low temperature side are mechanically linked. The values of these resistors constituting the temperature setting circuit B are the continuous change outputs Qla and Qlb that enable the indoor temperature setting of 120°C to 250°C at the volume change position X1 of 0.0 to 1.0.
is obtained, and the step outputs Q2a and Q2b are set so as to obtain step outputs Q2a and Q2b that enable setting of the indoor temperature of 3(1)C at the east point E which deviates to the left from 0.0 of the volume change position X1.

Specifically, R6=2.2KΩ, R8l+R82=1.8
65KΩ, Rll=27KΩ, R■=0~? Ω, R
The value of 8l is the second characteristic P2 and the step outputs Q2a, Q2b.
The intersection point with the yeast cooking temperature is set to approximately 30C. In particular, the OFF step output Q2b is the first characteristic P
The resistor R8l should be set so that it does not intersect with 1, or even if it does, it intersects at a temperature sufficiently lower than the detection temperature of 30C.
The resistance value and the second characteristic P2 are set, and at least 0F
The potential of the F-step output Q2b needs to be set to be equal to or lower than the intersection J potential between the first characteristic P1 and the second characteristic P2. Cl and C2 are capacitors, and Rl2 is a resistor. X2
is a set temperature scale determined by the relationship with the first characteristic P1 and the set output characteristic Q, and the east point is displayed to the left of the 120C scale, and as shown in FIG. The knob 16 is provided in a manner corresponding to the sliding range of the knob 16.

CP2 is a second comparator, the potential set by resistors Rl5 and Rl4 is input to the negative input terminal, and the low temperature side terminal 1 potential of the changeover switch SW is input to the positive input terminal by the resistor Rl5.
When the changeover switch SW is on the low temperature side, an H output is output, and when the changeover switch SW is on the high temperature side, an L output is output, and the switching state of the changeover switch SW is detected.

C3 is a capacitor, and Rl6 is a resistor. D is a main control circuit including a microcomputer etc. which inputs the outputs of the first comparator CPl and the second comparator CP2 and outputs control signals for the burner 13 and the fan motor 7;
When the Pl output is H, the solenoid valve 12 is opened and the burner 13 is combusted, and when the Pl output is L, the solenoid valve 12 is closed and the burner 13 is stopped from burning.When the second comparator CP2 output is L, the fan 8 It outputs a fan control signal that rotates the fan 8 at high speed and rotates the fan 8 at low speed when it is H.

In the above configuration, when performing normal cooking at 120C to 250C, for example, when setting the cooking temperature to 20C) 0C, slide the knob 16 to 2 on the first set temperature scale.
Start cooking according to 0 (generation). In this position of the knob 16, the selector switch SW is on the high temperature side, and the temperature detection circuit A
The output has a first characteristic P1. At the beginning of cooking, the temperature in the cooking chamber is low and the detection circuit A output is sufficiently smaller than the setting circuit B output a, and the burner 13 burns with the comparator CPl output H.
The temperature inside room 1 rises. When the comparator CPl output is inverted to H, the setting circuit B output becomes b, and when the room temperature rises and the detection circuit A output reaches b'' corresponding to b in the first characteristic P1, the comparator CPl is inverted to L, and the burner 13 Combustion stops. Due to this stop, the room temperature decreases, and when the output of the detection circuit A decreases to the output a'' corresponding to the set circuit output a, which has decreased due to the L reversal of the comparator CPl, the comparator CPl is reversed to the H level again. ,
Thereafter, by repeating this process, the indoor temperature is maintained at around 200C. At this time, the output of the second comparator CP2 is L, and the fan 8 rotates at high speed, making the rotation suitable for high-temperature cooking. Also, 3
To perform CfC yeast fermentation cooking, variable resistance is required.
When the knob 16 is slid to the left to match the east point E, the set output becomes the step output Q2a2:Q2b, and at the same time the detection output switches to the second characteristic P2, temperature control is performed, and the room temperature becomes about 3CfC. The yeast is retained and fermented. At this time, since the output of the second comparator CP2 is inverted to H, the fan 8 rotates at a low speed suitable for low temperature cooking. As described above, knob 16 of variable resistor R■
By switching the changeover switch SW in accordance with the displacement of , temperature control is performed using the steep slope section Pla of the first characteristic P1 for high temperature cooking and the steep slope section P2a of the second characteristic P2 for yeast cooking. Accurate temperature control can be achieved by reducing the temperature change in the room due to the change in the output of the setting circuit B over the temperature range.

Also, if the selector switch SW does not switch to the low temperature side due to a failure when setting the yeast preparation, the detection output will be the first characteristic P1, but the set output will be the step output Q2a, Q2b.
Therefore, the OFF setting value Q2b does not intersect with the first characteristic P1, and the combustion signal of the burner 13 is not output from the comparator CPl. Therefore, the temperature inside the chamber 1 does not reach a temperature that would kill the yeast. Furthermore,
It is designed so that the intersection point between the second characteristic P2 and the step outputs Q2a and Q2b is approximately 30° C., and this design can be easily performed by first determining the characteristic P2 and then determining the value of the resistor R8l.

Note that the present invention is not limited to the above embodiment, and when the changeover switch SW is switched to the low temperature side, this switch S
A switch (not shown) may be provided to open the series circuit of resistors R2 and R4 in conjunction with W. Further, the circuit constants of the temperature detection circuit A and the temperature setting circuit B can be changed as appropriate. (F) Effects of the Invention According to the present invention configured as described above, accurate room temperature control can be performed not only in normal cooking but also in yeast cooking, and even if the temperature detection circuit output is not switched normally. There is no cooking failure because the yeast is not killed.

Further, by changing the setting circuit output stepwise, the yeast cooking temperature can be easily set by adjusting the range of change, which has great effects.

[Brief explanation of the drawing]

Fig. 1 is a partially removed perspective view of an open exterior case equipped with an embodiment of the present invention, Fig. 2 is a cross-sectional view of the open case, Fig. 3 is an electric circuit diagram of the embodiment, and Fig. 4 is a cross-sectional view of the open case. The figure is an output characteristic diagram of the same embodiment, Figure 5 is a temperature detection circuit diagram of the conventional example, and Figure 6 is a diagram of the temperature detection circuit of the conventional example.
The figure is an output characteristic diagram of the conventional example. A...Temperature detection circuit, B...Temperature setting circuit, Rt...Temperature sensitive resistance element, Rv...
・Variable resistance.

Claims (1)

[Claims] 1 In a device that controls a heat source for indoor temperature control by comparing the output of a temperature setting circuit including a variable resistor for indoor temperature setting and the output of a temperature detection circuit including a temperature sensitive resistance element for detecting indoor temperature, When the temperature is set to normal cooking and when the temperature is set to yeast cooking, the output characteristics of the temperature detection circuit are changed to a first temperature-to-potential output characteristic with a steep slope corresponding to the normal cooking temperature and a steep slope corresponding to the yeast cooking temperature. A temperature of an oven comprising a first switching means for switching to a second temperature versus potential output characteristic having a gradient portion, and a second switching means for changing the output of the temperature setting circuit in a stepwise manner to a lower temperature side when yeast cooking is set. control circuit.