JPH0632261B2 - Electric hot plate controller - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an electric hot plate used in general households.

2. Description of the Related Art Conventionally, in a control device for an electric hot plate, a temperature sensor detects the temperature at the bottom of the plate, and when the temperature rises to a set temperature, the heater continues to be energized until the set temperature is reached, and the set temperature is reached. At that point, the heater was not energized.

Problems to be Solved by the Invention However, in the temperature control method as described above, since the temperature continues to rise for a while even after the energization of the heater is stopped, the plate temperature rises to a temperature equal to or higher than the set temperature. I will end up. Then, as the set temperature becomes higher, the fluorine layer provided on the plate surface is more likely to be thermally deteriorated due to the temperature overshoot as described above. Therefore, the maximum temperature that can be set must be lower than the maximum temperature that the body can withstand by a temperature difference that overshoots. It had the disadvantage that the temperature had to be lowered.

In view of the above drawbacks, the present invention eliminates excessive temperature overshoot that occurs when the plate temperature rises, improves the durability of the fluorine surface coated on the plate, and raises the maximum settable temperature of an electric hot plate. A control device is provided.

Means for Solving the Problems In order to achieve the above object, the present invention provides a plate to be mounted on a main body, temperature detecting means for detecting the temperature of the plate, and temperature control for controlling the temperature of the plate to a predetermined temperature. Means, a heater power reduction means for reducing heater power controlled by the temperature control means, and a rise time measurement means for measuring a time required for temperature rise between predetermined temperatures when the plate temperature rises, The heater power reduction means sets the heater power from the temperature lower than a predetermined temperature lower than the control temperature to the control temperature at the temperature rising time from the start of energization until the plate temperature reaches the control temperature by the rising time. It is reduced by a duty equal to or greater than a certain value with a cycle of a predetermined time corresponding to the time measured by the measuring means, When the temperature of the heater reaches the control temperature and is higher than the temperature at which the rise time measurement is started, the heater power reduction operation is not performed.

Operation With this configuration, when the temperature rises from the start of energization until the plate temperature reaches the control temperature, the rise time measuring means measures the time required for temperature rise between constant temperatures, and the heater is adjusted according to this time. The power reduction means determines a date for reducing the heater power. As a result, when the plate temperature reaches a temperature lower than the control temperature by a certain temperature, the power supplied to the heater until the temperature reaches the control temperature is reduced by the duty determined by the heater power reduction means, and the rate of rise of the plate temperature is increased. Becomes smaller. Therefore, the temperature rises excessively with respect to the desired control temperature, the life of the fluorine layer is extended, and the maximum settable temperature can be raised. Further, when the temperature of the plate reaches the control temperature and is higher than the temperature at which the setting of the rising time is started, the heater power is controlled to 0 or full power to control the plate temperature. Therefore, when the food is put on the plate, the full power is immediately obtained and the temperature can be quickly restored.

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, in which 1 is an AC power supply, and a heater 3 is energized via a power switch 2. A relay contact 5a for connecting and disconnecting electricity is inserted in the energizing circuit of the heater 3, and the relay contact 5a is driven by a relay coil 5b. The temperature of the plate is detected by the temperature detecting means 6, and the temperature control means 8 is controlled. The temperature control means 8 is adapted to the user is controlled even controlled temperature selection switch 7 that selects the desired plate temperature, the control temperature selection switch 7, theta ₃ at a temperature characteristic diagram of Figure 3, Three types of control temperatures, θ ₄ and θ ₅ , can be selected. That is, the temperature control device 8 receives the output of the temperature detection means 6 and adjusts the temperature at the control temperature selected by the control temperature selection switch 7, and by pressing the control temperature selection switch 7. It is supposed to start working.

9 indicates that when the temperature control means 8 starts operating and the output of the temperature detection means 6 at that time is lower than Q ₁ shown in the temperature characteristic diagram of FIG. 3, the temperature rises from θ ₁ to θ ₂ Is a rise time measuring means for measuring the time during which the heater power is reduced. The heater power reduction means 10 has a plate temperature lower than the control temperature selected by the control temperature selection switch 7 by a constant temperature. In this embodiment, when the control temperature is θ ₅ in the temperature characteristic diagram of FIG. 3, θ ₄ , θ ₄ then θ ₃ , θ ₃
In the case of, the heater power is reduced with a duty whose cycle is a predetermined time corresponding to the time measured by the rise time measuring means 9 until the temperature reaches the control temperature from the temperature point of θ _2. The heater power is reduced by turning on / off the relay contact 5a via the temperature control means 8. Further, when the temperature of the plate reaches the control temperature and is higher than the temperature θ _{1 at} which the rise time measurement is started, the heater power reduction operation is not performed.

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

First, in step 101, the control temperature selection switch 7 is operated to select a desired control temperature. Here, assuming that the control temperature is selected as θ ₅ , the temperature control operation is started at the same time, and if the temperature θ at the start point is lower than θ _{5 in} step 102, the process proceeds to step 103, and if θ is θ ₅ or more, the plate is operated. Since the temperature is higher than the control temperature, the energization of the heater is stopped and the process is repeated until θ <θ ₅ . On the other hand, if the process proceeds to step 103, for example, the duty factor is set to 1
6/16 (16 is a predetermined time with a period of 16 seconds), and the process proceeds to step 104, and if the current temperature θ is higher than the temperature θ _{1 at} which the rise time is measured, the measurement cannot be performed, and the process returns to step 102. . If it is lower than θ ₁ , the process proceeds to step 105, and if the current temperature θ is not within the range of θ ₁ ≦ θ ≦ ₂ , the process proceeds to step 106 and if θ is not θ ≧ θ ₄ , the process returns to step 105 and θ ₁ ≦ θ ≦ ₂ . Repeat until
When the plate temperature rises and θ ₁ ≦ θ ≦ ₂ in step 105, the time is added every 1 second in step 107, and the time is repeatedly counted until it goes out of the range of θ ₁ ≦ θ ≦ ₂ , and the time is counted. .

When θ is out of the range of θ ₁ ≤ θ ≤ ₂ , the process proceeds to step 106,
Wait until θ ≧ θ _4, Step 1 becomes a theta ≧ theta ₄
In step 08, power is supplied at a duty ratio R corresponding to the time T shown in the table below according to the time T counted in step 107. The current is supplied at this duty ratio R until θ ≧ θ _{5 in} step 107, that is, until the control temperature is reached. When θ ≧ θ ₅ , the process returns to step 102 and the same operation is repeated thereafter.

As described above, according to the present embodiment, the plate placed on the main body, the temperature detecting means for detecting the temperature of the plate, and the relay connected in series to the heater are changed in temperature to reach a predetermined temperature. By providing the temperature control means for controlling, the heater power reducing means, and the rise time measuring means for measuring the time required for temperature rise between constant temperatures, excessive overshoot when the plate temperature rises is eliminated and rise By measuring the time, it is possible to detect the load state of the plate, and it is possible to reduce the power for preventing overshoot with an appropriate power that matches the load state. Also, when the temperature of the plate reaches the control temperature and is higher than the temperature at which the rise time measurement is started, the heater power reduction operation is disabled so that when the food is put on the plate, full power is immediately obtained. The return is quick and cooking performance can be improved.

As is apparent from the above-described embodiment, the controller of the electric hot plate according to the present invention is capable of measuring the time when the plate temperature rises, with or without the plate lid, high and low temperature, and power supply voltage. By this, it is possible to detect and always reduce the power with an appropriate power to prevent overshoot. In particular, by reducing the heater power with a duty that is equal to or greater than a certain value with a cycle of a predetermined time, the heater power will not be reduced too much even if the time is mistakenly shortened due to noise during temperature measurement. Since the heater is energized on and off in a predetermined time unit, it is possible to intermittently energize the heater using a relay. As a result, the comparison of the time required for the temperature rise becomes three steps of the comparison with the upper limit time and the lower limit time, so that only three programs are required and the program can be simplified. Further, the heater energization control means can be downsized, and malfunction due to noise can be eliminated. Also, when the plate temperature reaches the control temperature,
When the temperature is higher than the temperature at which the rise time is measured, the heater power reduction operation is disabled so that when the food is put on the plate, it immediately becomes full power.
The temperature can be restored quickly and cooking performance can be improved. Then, the durability of the fluororesin coated on the plate surface is improved, and the settable maximum temperature can be raised, which has a great practical effect.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of an electric hot plate controller according to an embodiment of the present invention, FIG. 2 is a flow chart of a microcomputer program used in the embodiment, and FIG. 3 is a plate temperature rise during temperature control. It is a characteristic diagram. 3 ... Heater, 6 ... Temperature detecting means, 8 ... Temperature controlling means, 9 ... Rise time measuring means, 10 ... Heater power reducing means.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuhiko Tanaka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-63-45782 (JP, A)

Claims (1)

[Claims] 1. A plate to be placed on a main body, temperature detecting means for detecting the temperature of the plate, temperature control means for controlling the temperature of the plate to a predetermined temperature, and heater power controlled by the temperature control means. The heater power reduction means for reducing the temperature, and the rise time measurement means for measuring the time required for the temperature rise between the predetermined temperatures when the plate temperature rises, wherein the heater power reduction means is the At the time of rising of the temperature until the plate temperature reaches the control temperature, a predetermined time corresponding to the time measured by the rising time measuring means from the temperature lower than the control temperature by a predetermined temperature to the control temperature is cycled. The temperature of the plate reaches the control temperature and the rise time is measured. Not to operate the heater power reduction is higher than the temperature to start the electric hotplate controller.