JPH0445950B2 - - 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 configuration was such that the heater was de-energized.

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 may rise to a temperature higher than the set temperature. The higher the set temperature, the more likely the fluorine on the plate surface will be thermally degraded due to the temperature overshoot mentioned above, and for this reason, the maximum temperature that can be set is the highest temperature that the vessel can withstand The problem is that the maximum temperature that can be set must be lowered even though there are foods that must be cooked at the highest temperature possible. was.

In view of the above-mentioned problems, an object of the present invention is to eliminate the excessive temperature overshoot that occurs when the plate temperature rises, improve the durability of the bare surface, and increase the maximum settable temperature.

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, and a temperature control means for controlling the temperature at a plurality of temperature points. and a control temperature setting means for setting the temperature controlled by the temperature control means, a heater power reduction means for reducing the heater power, and a relay energization rate determining means for determining the relay energization rate in the heater power reduction means. ing.

Effect With this configuration, the temperature controlled by the temperature control means is first set by the control temperature setting means, the temperature control operation is started, and the temperature detection means is controlled until the plate temperature reaches the control temperature. When it is detected that the temperature has reached a certain temperature lower than the temperature, the relay energization rate in the heater power reduction means is determined to be the energization rate according to the control temperature set by the control temperature setting means, and this energization rate is turned on or off. It is repeated a certain number of times. As a result, overshoot of the plate temperature with respect to the control temperature can be suppressed to just the right amount, compared to when electricity 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, in which 1 is an AC power supply, power switch 2,
A series circuit of a heater 3 and a relay contact 4a for turning on and off electricity to the heater is connected. Further, the relay contact 4a is driven by a relay coil 4b, and the relay 4 is constituted by the relay contact 4a and the relay coil 4b. Outputs from a temperature detection means 5 for detecting the plate temperature and a control temperature setting means 6 for selecting and setting a desired plate temperature by a user using a control temperature selection switch 7 are input to a temperature control means 8. This control temperature setting means 6 is
Three types of control temperatures, θ ₄ , θ _{3 , and} θ ₂ shown in the figure, can be selected.

Further, the temperature control means 8 controls the energization rate of the relay 4 to adjust the heater power in order to adjust the temperature at the control temperature set by the control temperature setting means 6. Further, the operation is started by pressing the control temperature selection switch 7. The relay energization rate is determined according to the control temperature set by the control temperature setting means 6. The relay energization rate determination means 9 is connected to the heater power reduction means 10. When the temperature control means 8 starts operating and the temperature detection means 5 detects that the temperature has reached a temperature lower than the control temperature set at that time, the heater power reduction means 10 is connected to a relay determined by the relay energization rate determination means 9. Even with an on/off energization rate of , the heater power is reduced by turning the relay on and off twice, once once.

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. 3 and the diagram showing relay energization rate setting shown in FIG. 4.

First, in step 101, the control temperature selection switch 7 is operated to select and set a desired control temperature _θS . Here, if the control temperature θ _S is selected and set to θ ₄ shown in FIG. 2, θ ₄ is the control temperature and θ ₃ is the starting point of the heater power reduction means. At the same time, the temperature control operation is started, and in step 102, the temperature θ at the start point is θ≧ _θ4.
If so, the plate temperature is higher than the control temperature, so proceed to step 103, set the relay on/off period to 16 seconds according to the relay energization rate in Figure 4, and set the relay energization rate to 0/16, that is, the relay energization rate is 0/16. remains off and repeats until θ<θ ₄ . If θ<θ ₄ , proceed to step 104 and similarly set the relay energization rate to 16/16 according to FIG.
If the plate temperature has not reached the control temperature even once since the start of the temperature control operation in step 105, and the heater power reduction means has not performed the power reduction operation even once, the process proceeds to the next step 106. If not, return 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. If θ<θ ₃ , the process returns to step 102; if θ≧θ ₃ , the process proceeds to the next step 107. move on. In step 107, the relay energization rate is determined based on the set control temperature θ _S. If θ _S = θ ₄ , the process goes to step 108, and if θ _S = θ ₃ , the process goes to step 108.
Step 109; if θ _S =θ ₂ , step 110 is reached.

In this embodiment, the explanation is given as θ _S =θ ₄ , so in this case, the process goes to step 108 and the relay energization rate is set to 4.
According to the figure, it is 12/16. In the next step 111, it is checked whether the plate temperature θ has reached the control temperature θ _S , that is, θ _4. If it has not reached the control temperature θ S, the process proceeds to the next step 112, where the relay is turned on and off once, and the number of on and off times is N. is repeated until N≧2.
When the plate temperature θ reaches _θ4 or N becomes N≧2, the process returns to step 102, and since θ is higher than the control temperature _θ4 , the process proceeds to step 103, and the relay energization rate becomes 0/16 from FIG. , power supply to the heater is stopped. If θ < θ ₄ in step 102, the process proceeds to steps 104 and 105, but since the set temperature has been reached by 1 degree in step 105, the process does not proceed to step 106 but returns to step 102, and after that, steps 102 to 105 are repeated. It will be done.

Similarly, when the control temperature θ _S is set to θ ₃ , θ ₂ becomes the start temperature of the heater power reduction operation, the relay energization rate is reduced by 10/16, and the control temperature θ _S is set to θ ₂ .
If θ ₁ is the starting temperature of heater power reduction operation,
The relay energization rate is 8/16, reducing the amount of current to the heater. By performing the above-mentioned operations, overshoot when the plate temperature rises is prevented, and power reduction operation can be performed with just the right amount of electricity because the energization rate to the heater is reduced at the optimum energization rate for each control temperature. It is. Furthermore, since another control temperature point is used as the starting temperature for the heater power reduction operation, the number of temperature points to be detected can be reduced.

Effects of the Invention As described above, the present invention is driven by a temperature detection means for detecting the temperature of a plate, a temperature control means for controlling the temperature at a plurality of temperature points, a control temperature setting means, and a temperature control means. control set by a relay contact connected in series to the motor, a heater power reduction means that reduces the heater power by turning the relay contact on and off at a certain period and repeating this a certain number of times, and a control temperature setting means. By providing a relay energization rate determining means that sets the relay on/off period according to the temperature, excessive overshoot when the plate temperature rises can be prevented. This improves the durability of the system, and also makes it possible to raise the maximum temperature that can be set. In addition, even if the plate temperature decreases due to the presence or absence of a lid on the plate, the high or low temperature, or the magnitude of the power supply voltage, the power reduction rate according to each control temperature and the power reduction operation only a certain number of times can be used. , after a certain number of times, it returns to the maximum power and can raise 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 flowchart of a microcomputer used in the control device. FIG. 4 is a diagram showing relay energization rate setting. 3... Heater, 4... Relay, 5... Temperature detection means, 6... Control temperature setting means, 8... Temperature control means, 9... Relay energization rate determining means, 10...
Heater power reduction means.

Claims (1)

[Claims] 1. A plate having a heater, a temperature detection means for detecting the temperature of the plate, a temperature control means for controlling the temperature at a plurality of temperature points, a control temperature setting means for setting the control temperature controlled by the temperature control means, A relay contact connected in series to a heater driven by a temperature control means and a constant temperature lower than the control temperature when the temperature rises from the start of the temperature control operation until the plate temperature reaches the control temperature. Heater power reduction means for reducing heater power by turning on and off a relay contact at a constant cycle and repeating this a certain number of times until the temperature reaches the control temperature; and a relay on/off cycle in the heater power reduction means. A control device for an electric hot plate, comprising: a relay energization rate determining means for determining a relay on/off period according to a control temperature set by the control temperature setting means.