JPH02239825A - Controller for electric hot plate - Google Patents

Abstract

PURPOSE:To sharply reduce overshoot by reducing the power of the heater when the plate temperature reaches a temperature lower than the control temperature by a definite temperature difference. CONSTITUTION:A temperature control means 7 starts an action, and when the fact that the temperature reaches the temperature lower by one rank than the control temperature selected by a control temperature selecting switch 6 is detected by a temperature detecting means 5 at such a time, by changingly reducing a relay current flowing rate executed with the temperature control means 7, the power of the heater is reduced. A time from a time when the relay current flowing rate is changingly reduced by a heater power reducing means 8 is counted by a time counting means 9, and after a prescribed value, the heater power reducing means 8 is operated at the relay energizing rate before the reduction again.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for an electric hot plate used in general households.

Conventional technology Conventional electric hot plate control devices use a temperature sensor to detect the temperature at the bottom of the plate, and when the temperature rises to the set temperature, the heater continues to be energized until the set temperature is reached, and when the set temperature is reached, the heater is turned off. The power supply had been stopped. (For example, Japanese Unexamined Patent Publication No. 63-166188) Problems to be Solved by the Invention In the 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 may significantly exceed the set temperature. A so-called large overshoot phenomenon occurred, in which the temperature rose to above . For this reason, the higher the set temperature, the greater the overshoot and the easier it is to deteriorate the fluorine layer treated on the plate surface, so the maximum temperature that can be set must be set lower by the amount of overshoot. Even though some cooking requires cooking at as high a temperature as possible, there is a drawback that the maximum temperature that can be set must be lowered, and in the case of foods with a small thermal load, the overshoe 1 ~ is large, resulting in excessive burntness. There were some drawbacks as well.

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and an electric hot spring plate I-1 includes a temperature detection means for detecting the temperature of the electric hot spring 1, and a temperature detection means for detecting the temperature of the electric hot spring I. a temperature control means for controlling the temperature, a relay connected in series to the heater which is controlled by the humidity control means;
It consists of a heater power reduction means based on the energization rate and a time counter 1 means, thereby eliminating excessive overshoeing of the temperature in plays 1 to 1.

Operation With the above configuration, the control operation by the temperature control means is started, and the temperature detection means detects that the temperature has reached a certain temperature lower than the control temperature until the play 1 temperature reaches the control temperature. When detected, the heater power reduction means lowers the relay energization rate, and at the same time, the time counter I means maintains this state until the elapsed time to star 1 reaches a predetermined time.

EXAMPLES Below, examples of the present invention will be explained with reference to FIGS. 1 to 3.

Fig. 11 shows an electric hot spring 11 brake according to an embodiment of the present invention.
In the circuit block diagram of the control device 1., 1 is an AC power supply, and the control device 1.
Electricity is applied to a heater 3 provided near (not shown). A relay contact 4a is inserted into the energizing circuit of the heater 3 to turn on/off the energization, and this relay contact 4a is moved by a relay coil 4b. The temperature of the play 1 is detected by a temperature detection means 5 provided near the play 1, and is controlled by a temperature control means 7 which receives input from the temperature detection means 5. ing. Also, this temperature control means 7 controls the play 1 desired by the user.
- The temperature is controlled based on the input from the control temperature selection switch 6 which selects the temperature.
, T4 can be selected. In other words, the temperature control means 7 receives the output of the temperature detection means 5 as an input, adjusts the temperature based on the control temperature Tn selected by the control temperature selection switch 6, and adjusts the heater power by controlling the energization rate of the relay 4. The operation starts when the control temperature selection switch 6 is pressed. 8 is a heater power reduction means, which detects when the temperature control means 7 starts operating and reaches a temperature Tn-1 which is one rank lower than the control temperature Tn selected by the control temperature selection switch 6 at that time. 5, the temperature control means 7
The heater power is reduced by changing and reducing the relay energization rate. 9 is a time counting means, which counts the time from the time when the heater power reduction means 8 changed and reduced the relay energization rate to a predetermined value t.
After n, the heater power reduction means 8 is operated again to the relay energization rate before reduction.

Electric hot plate 1 of this embodiment configured as described above
The operation of the control device will be explained below with reference to flowchart 1 in FIG. 3.

First, in step 101, operate the control temperature selection switch 6 to select the desired control temperature (T4 is selected in this figure), T3 becomes the starting point of the heater power reduction means, and at the same time the temperature control operation starts. Step 10
In step 2, the time counter 1/means 9 is initialized, that is, the star 1 hour is set to 0, and the process proceeds to the next step 103. If the temperature T at the start point is T≧T4, the plate temperature is higher than the control temperature. The process proceeds to step 104, where the timer is initialized (20 seconds), and then the process proceeds to step 105, where the on/off cycle of the relay is set to 16 seconds, and the relay energization rate is maintained at 0716, that is, the non-energized state. When T<T4, the process advances to step 106 and the relay energization rate is set to 1. 6
/ 16, and in step 107 it is determined whether the plate temperature T is a temperature at which the heater power reduction means 8 is started. If T<T3, the process returns to step 103, and if T≧
In the case of T3, the process advances to step 108. Step 108
Then, time counter l・means 9 calculates the passing time t by count 1・
In the next step 109, if the elapsed time t is t<tn (predetermined set time), the process proceeds to step 110, where the relay energization rate is reduced to 10/16, and heating is continued to suppress overshoot in the next step 111. Plate temperature T<
In the case of T4, return to step 108 and set the energization rate to 10/16.
is maintained, and if T≧T4, the process returns to step 103. In steps 104 and 105, the current is not applied for a while to cool the plate temperature T, and if T<T4, the process returns to step 1.
Proceed to 06, and repeat this routine thereafter to set the control temperature T.
Maintain 4. On the other hand, if the elapsed time t is t≧tn with respect to the set time tn in step 109, step 10
After returning to step 3 and cooling for a while in steps 104 and 105, when T<T4, the process proceeds to step 106, and thereafter this routine is repeated to maintain the control temperature T4.

Similarly, the control temperature selected by the temperature control means 7 is T.
3, T2 becomes the starting temperature for heater power reduction, and when the control temperature is T2, T1 becomes the starting temperature for heater power reduction.The above operation suppresses overshoot, while reducing power In order to avoid a situation where the temperature does not rise to the control temperature easily due to the influence of the temperature and load, or conversely the temperature decreases, consideration is given so that the process returns to steps 103 and 106 after a certain period of time tn and heating is performed at the maximum output. There is.

The heater 3 performs an on-off operation to maintain the control temperature T4 by adding a load (cooked food), but if the load is large, the plate temperature T decreases significantly (T<T3), so it reaches the maximum in steps 103 and 106. When the load is small, the plate temperature T is T≧T3 and the amount of decrease is small, so the heating output is suppressed in steps 108, 109, 110, and 111, and the heating amount is adjusted to the load, resulting in insufficient heating or There are no problems such as burning food due to overheating.

Effects of the Invention According to the present invention, the power of the heater is reduced when the plate temperature reaches a certain temperature lower than the control temperature, which greatly reduces and solves the overshoot, which is a drawback of conventional models. It has the following effects.

171■ The situation in which the temperature does not rise to the control temperature due to the influence of the ambient temperature and load due to power reduction, or on the contrary, the temperature drops, is solved by providing a time counting means.

■If microcomputer control is used as the time counting means, the built-in timer function can be used, so no special parts are required.

■Since the setting time of the time counting means can be set and changed in seconds, it is possible to precisely respond to the thermal mass and heating output of plates and food items, and it is also possible to easily respond to changes in the control program.

■When the plate temperature becomes higher than the control temperature and the non-energized state is repeated, the time of the time counting means is initialized. From then on, even if the temperature becomes lower than the control temperature and high energization rate heating control is performed, the passing time of the time counting means will be Normal operation from 0 to star 1 is guaranteed.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram of an electric hot plate showing an embodiment of the present invention, Fig. 2 is a chart of plate temperature rise characteristics during temperature control, and Fig. 3 is a diagram showing the temperature rise characteristic of the electric hot plate programmed into the temperature control means. It is a flowchart of a sequence. 3... Heater, 4... Relay 5... Temperature detection means, 7... Temperature control means, 8... Heater power reduction means, 9... Time counting means.

Claims (1)

[Claims] A plate mounted on the main body, a temperature detection means (5) for detecting the plate temperature, a temperature control means (7) for controlling the plate temperature, and a heater (3) driven by the temperature control means (7) are connected in series. , a heater power reduction means (8) according to the on/off energization rate of the relay (4), and a time count means (9), When the plate temperature is a certain temperature lower than the predetermined control temperature, the heater power reducing means (8) lowers the energization rate to the relay (4) to reduce the heater power, and the time counting means (9) A control device for an electric hot plate characterized by having a circuit configuration that counts the elapsed time after power reduction and performs a heater power reduction operation until a predetermined time is reached.