JPS63161916A - Safety apparatus of electric cooker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION This invention relates to a safety device for cooking appliances such as electric ranges having electric heating elements.

Conventional technology Conventional electric ranges mainly consisted of an electric heating element such as a sheathed heater and a wattage controller to adjust the heating power, but in recent years electronic circuits have been used to adjust the temperature of the heated object. Devices are beginning to appear that can shut off the power and stop heating if the temperature rises abnormally. An example of such an electric range is shown in FIG. In FIG. 5, 1 is an electric heating element such as a sheathed heater, and a relay contact 2 is inserted into its energizing circuit. The relay contact 2 is controlled by a drive circuit 3 including a relay coil and a coil, and the drive circuit 3 is controlled by a temperature detection circuit 4. Note that 6 is a temperature detection element such as a negative characteristic thermistor. The operation of this configuration is as follows.

Now, when the electric heating element 1 is energized, the relay contact 2 is in a closed state. This state continues if the temperature of the heated object is the temperature under normal usage conditions.

Next, when the temperature of the object to be heated becomes abnormal, the temperature detection circuit 4 is activated due to a change in the resistance value of the temperature detection element 5 provided in contact with the object to be heated, and the drive of the relay coil 3 is stopped. , contact 2 is opened to stop heating.

Problems to be Solved by the Invention However, the configuration of the electric range described above has the disadvantage that when the power switch is turned on, electricity is applied even though there is no object to be heated, and the electric heating element 1 becomes high temperature. was. Since the temperature detection element 6 is provided so as to be in contact with the object to be heated, the temperature detection element 5 cannot detect this dry firing state either. Further, when the electric heating element 1 reaches a high temperature, its lifespan is shortened, and various parts of the main body are adversely affected by the heat.

In order to solve the above problems, the present invention is an electric cooking device having an electric heating element, which compares and outputs the detected voltage with a temperature detecting element such as a negative characteristic thermistor. a control system consisting of a temperature detection circuit including a voltage comparator, etc., a drive circuit controlled by the temperature detection circuit, a power control means for the electric heating element controlled by the drive circuit, and The safety device is equipped with a safety switch that is activated by a heated object placed thereon, and a contact point of the safety switch is provided in a control system circuit.

Operation With the above configuration, when the object to be heated is placed on the electric heating element, the contacts of the safety switch close the circuit of the control system.

Therefore, an output is generated from the temperature detection circuit, which drives the relay and closes the contacts, thereby energizing the electric heating element and heating it.

Next, when the object to be heated is removed, the control system is cut off, the contacts of the safety switch are opened, and the relay contacts are opened, stopping power supply to the electric heating element.

As described above, with this configuration, if there is an object to be heated, electricity is applied to heat it, and if there is not, electricity is stopped.

Example Embodiments of the present invention are shown from FIG. 1 to FIG. 4.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which 1 is an electric heating element, 2 is a relay contact, 3 is a relay coil and its driving circuit, 4 is a temperature detection circuit consisting of a voltage comparator, etc.; is a temperature detection element, which has the same structure as the conventional example, so a description thereof will be omitted. 6 and 6'
is a contact point of a safety switch that is driven by placing an object to be heated, and is connected to the temperature detection element 6 in series or in parallel as shown by the dotted line in the figure.

Now, if contact 6 is closed and the temperature is normal, relay contact 2 is closed.
is closed and the main switch is on, the electric heating element 1 is energized.

FIG. 2 is a sectional view showing the configuration of the safety switch 6 that is activated by the object to be heated. 1 is an electric heating element, and 5 is a temperature detection element. A case 7 of the temperature detection element 6 is heated upward by a spring 8.

The safety switch 6 is connected to the case 7 by a lever 9°1o. Therefore, when the case 7 is pushed down by the pot 11 which is the object to be heated, the contact point of the safety switch 6 is closed by the lever 10.

FIGS. 3 and 4 show examples of the temperature detection circuit 4 using a voltage comparator, and show two cases in which the safety switch contact 6 is connected in parallel to the temperature detection element 6 and one in which it is connected in series. .

In Fig. 3, 6 is a temperature detection element, 6 is a contact of a safety switch activated by the object to be heated, 12 is a voltage comparator that receives the signal from the temperature detection element 6 and compares and outputs it, 13 is a relay coil, and 14 is a transistor. These constitute the drive circuit.

In this circuit, when the resistance value of the temperature detection element 6 drops below a predetermined value due to abnormal temperature, or when the contact 6 of the safety switch is closed, the transistor 14 is turned off.
Relay contact 2 is opened to stop energizing the electric heating element.

In FIG. 4, a voltage comparator 15 is separately provided,
The detected temperature of this voltage comparator is set to operate at a value lower than the normal operating temperature range. (-6℃～-
20°C) Therefore, in this circuit, the transistor 14 is turned off when the temperature detection element 5 has a disconnection failure, when the contact e of the safety switch is opened, and when the voltage comparator 12 indicates an abnormal temperature. Relay contact 2 is opened to stop energizing the electric heating element.

Effects of the Invention As described in the above embodiments, when the safety device of the present invention is used, the electricity to the electric heating element is stopped when there is no object to be heated, which reduces the operating temperature of the electric heating element and shortens its life. Not only can it be extended, but also the adverse effects of temperature on the main body can be eliminated.

In particular, the control system is equipped with a safety switch, so if there is a failure in the control system circuit, the power will be turned on even if there is no object to be heated, so you can know in advance that the safety device will not operate. , more secure.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a safety device for an electric cooker showing an embodiment of the present invention, Figure 2 is a sectional view of the safety switch section, Figures 3 and 4 are circuit diagrams, and Figure 6 is It is a block diagram of an electric range showing a conventional example. 1... Electric heating element, 2... Relay contact (power control means), 3... Drive circuit, 4...
... Temperature detection circuit, 5 ... Temperature detection element, 6
・・・・・・Safety switch contact. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A cooking appliance such as an electric range having an electric heating element, which includes a control means consisting of a temperature detection element, a temperature detection circuit, and a drive circuit, a power control means connected in series to the electric heating element, and an electric heating element. A safety device for an electric cooker, comprising a safety switch activated by an object to be heated placed on the upper part of the body, and the safety switch is provided in a circuit of the control means. (2) The safety device for an electric cooker according to claim 1, wherein the contact of the switch is connected in series or in parallel with the temperature detection element.