JPH0445951B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electric hot plate used in general households.

Conventional technology Conventionally, in the control device of an electric hot plate, a temperature sensor detects the temperature at the bottom of the plate, and when the temperature is raised to a set temperature, the heater is continuously energized until the set temperature is reached, and when the set temperature is reached. The power to the heater had been stopped.

Problems to be Solved by the Invention However, in the temperature control method described above, the temperature continues to rise for a while even after the power supply to the heater is stopped, so the plate temperature rises to a temperature higher than the set temperature. . The higher the set temperature is, the more likely the fluorine layer provided on the plate surface will be thermally degraded due to temperature overshoot as described above. Therefore, the maximum temperature that can be set must be lower than the maximum temperature that the container can withstand by the temperature difference that overshoots, and even though there are foods that must be cooked at the highest possible temperature, it is possible to set the maximum temperature. This had the disadvantage that the maximum temperature had to be lowered.

In view of the above drawbacks, the present invention aims to eliminate the excessive temperature overshoot that occurs when the plate temperature rises, improve the durability of the flat surface coated on the plate, and increase the maximum settable temperature. The present invention provides a control device for the following.

Means for Solving the Problems To achieve this object, the electric hot plate control device of the present invention includes a temperature detection means for detecting the temperature of the plate, a temperature control means for controlling the temperature of the plate, and a temperature control device for controlling the temperature of the plate. A relay connected in series to a heater driven by a heater, a heater power reduction means based on an on/off energization rate of the relay, and a counting means for counting the number of on/off times of the relay.

Effect With this configuration, the temperature control operation by the temperature control means is started, and until the plate temperature reaches the control temperature, when the temperature detection means detects that the temperature has reached a certain temperature lower than the control temperature, The heater power reduction means lowers the relay energization rate until the counting means counts the number of times the relay is turned on and off a certain number of times.

As a result, overshoot of the plate temperature with respect to the control temperature can be significantly suppressed compared to when the current is continued until the control temperature is reached.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram showing the configuration of an embodiment of the present invention. Reference numeral 1 designates an AC power source, which is connected to a heater 3 via a power switch 2. In FIG. A relay contact 4a is inserted into the energizing circuit of the heater 3 to cut off the energization.
a is driven by a relay coil 4b. The temperature of the plate is detected by a temperature detection means 5, and the temperature detection means 5 is adapted to control a temperature control means 7. The temperature control means 7 is also controlled by a control temperature selection switch 6 for selecting the plate temperature desired by the user _. , θ ₂ , and θ ₃ can be selected. That is, the temperature control means 7 inputs the output of the temperature detection means 5, adjusts the temperature at the control temperature selected by the control temperature selection switch 6, and controls the temperature at the control temperature selected by the control temperature selection switch 6.
The heater power is adjusted by the energization rate control in b. The operation starts when the control temperature selection switch 6 is pressed.

8, when the temperature control means starts operating and the temperature detection means 5 detects that the temperature has reached a temperature lower than the control temperature selected at that time, the relay energization rate carried out by the temperature control means 7 is changed and reduced. Heater power reduction means 9 reduces the power of the heater by counting the on/off signals sent to the relay 4 by the temperature control means from the time when the heater power reduction means 8 changes and reduces the relay energization rate, and
If one cycle of off is counted as one time and counted twice,
This is relay on/off count means for stopping the operation of the heater power reduction means 8.

The operation of the electric hot plate control device constructed as described above will be explained below with reference to the flowchart shown in FIG.

First, in step 101, control temperature selection switch 6
and select the desired control temperature. Here, if the control temperature is selected at θ ₄ shown in Figure 2, θ ₃
becomes the starting point of the heater power reduction means, and the temperature control operation is started at the same time.If the temperature θ at the start point is θ≧ _θ4 in step 102, the plate temperature is higher than the control temperature, so the process advances to step 103 and the relay is activated. The on/off cycle of is 16 seconds, the relay energization rate is 0/16, that is, the relay remains off,
Repeat until θ<θ ₄ If θ<θ ₄ , step
Proceed to step 104, set the relay energization rate to 16/16, and step
In step 105, if the plate temperature has not reached the control temperature at all and the power has not been reduced by the heater power reduction means, the process proceeds to the next step 106; otherwise, the process returns to step 102. . Proceeding to step 106, it is determined whether the plate temperature θ is a temperature at which the heater power reduction means is started, and if θ<θ ₃ , the process returns to step 102, and if θ≧θ ₃
If so, proceed to the next step 107. Step 107
Then, counting of the relay on/off circuit is started, and at the same time, the relay energization rate is set to 10/10 in step 108.
Reduced to 16. Next, in step 109, if the relay on/off count N is 2, the process returns to step 102.
The relay energization rate is adjusted in step 104 until θ≧ _θ4 .
16/16, and repeats the operation of returning to step 102 via step 105.

On the other hand, if N<2 in step 109, step
Unless θ≧θ ₄ in step 110, the heater power continues to be reduced at the energization rate in step 108. step
If θ≧θ ₄ at step 110, return to step 102,
Proceeding to step 103, the relay energization rate is set to 0/16 and energization to the heater is stopped, and in step 102, θ<
Repeat until θ ₄ is reached.

Similarly, when the control temperature selected by the control temperature setting switch 7 is θ ₃ , θ ₂ is the start temperature for heater power reduction, and when the control temperature is θ ₂ , θ ₁ is the start temperature for heater power reduction. By performing the above-mentioned operation, the overshoot when the plate temperature rises is suppressed, and even when the heat load on the plate increases, the power is reduced a certain number of times, so the plate temperature decreases due to the power reduction. You can avoid the worst case scenario of leaving.

Effects of the Invention As is clear from the description of the embodiments above, the present invention includes a temperature detection means for detecting the temperature of the plate;
By providing a temperature control means for controlling the temperature of the plate, a relay connected in series with the heater, a means for reducing the heater power by using the on/off relay energization rate, and a counting means for counting the number of times the relay is turned on and off, the plate temperature can be controlled. Excessive overshoot at startup can be prevented, the durability of the fluororesin coated on the plate surface is improved, and the maximum temperature that can be set can also be raised. In addition, depending on whether the plate has a lid or not, the temperature is high or low, and the power supply voltage is high or low, if the power is reduced when the plate temperature rises, even if the plate temperature stays the same or decreases, the power will be reduced by relaying a certain number of times. This has great practical effects, such as returning to the maximum power after a certain number of times and raising the plate temperature to the control temperature.

[Brief explanation of the drawing]

Fig. 1 is a circuit block diagram of a control device for an electric hot plate according to an embodiment of the present invention, Fig. 2 is a chart of plate temperature rise characteristics during temperature control, and Fig. 3 is a program of a microcomputer used in the same embodiment. It is a flowchart diagram. 3...Heater, 4...Relay, 5...Temperature detection means, 7...Temperature control means, 8...Heater power reduction means, 9...Relay on/off frequency counting means.

Claims (1)

[Claims] 1. A plate placed on the main body, a temperature detection means for detecting the temperature of the plate, a temperature control means for controlling the temperature of the plate, a relay connected in series to a heater driven by the temperature control means,
It has a heater power reduction means based on the energization rate of the on/off of the relay, and a counting means for counting the number of on/off times of the relay, and the plate temperature reaches a predetermined control temperature after starting the temperature control operation. When the temperature rises up to, the heater power reduction means lowers the energization rate to the relay from a certain temperature lower than the predetermined control temperature.
While reducing the heater power, the counting means counts the number of on/off times of the relay,
A control device for an electric hot plate characterized by performing a heater power reduction operation until a predetermined number of times is counted.