JPS63161915A - 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. 6, 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 relay coil and a coil drive circuit 3, and the drive circuit 3 is controlled by a temperature detection circuit 4. Note that 5 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 6 provided in contact with the object to be heated, and the drive of the relay coil 3 is stopped. Then, contact 2 is opened and heating is stopped.

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 5 is provided so as to be in contact with the object to be heated, the temperature detection element 6 cannot detect this dry firing state either. Furthermore, 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.

Means for Solving All Problems In order to solve the above problems, the present invention provides an electric heating element k.
A temperature detection circuit comprising a temperature detection element such as a negative characteristic thermistor, a voltage comparator for comparing and outputting the detected voltage, a drive circuit controlled by the temperature detection circuit, and a drive circuit. It is equipped with a power control means connected in series to the electric heating element, and a safety switch operated by the object to be heated placed on the electric heating element, and the contacts of the safety switch are connected to the reference circuit of the temperature detection circuit. Connect in parallel or in series to form a safety device.

Operation With the above-described configuration, when the object to be heated is placed on the electric heating element, the contacts of the safety switch are closed if they are connected in series with the reference circuit of the temperature detection circuit, and are opened if they are connected in parallel.

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.

When the object to be heated is then removed, the contacts of the safety switch will open if in series with the temperature detection circuit and close if in parallel.

Each of these corresponds to a case where the temperature detection circuit detects a high temperature, so the output of the temperature detection circuit is stopped, the relay contact is opened, and the power supply to the electric heating element is stopped.

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.

Embodiment FIG. 1 to FIG. 4 show an embodiment of the present invention. 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, and since these are similar in configuration to the conventional array, their explanation will be omitted. 6 and 6' are contacts of a safety switch that is driven by placing an object to be heated, and are connected in series or in parallel to the reference circuit 7 of the temperature detection circuit 4.

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. The case T of the temperature detection element 6 is heated upward by a spring 8. The switch 6 is connected to the case 7 by levers 9 and 1o. Therefore, assuming that the case 7 is pushed down by the pot 11 which is the object to be heated, the contact of the safety switch 6 is closed by /<-10.

FIGS. 3 and 4 show embodiments of the temperature detection circuit 4 using a voltage comparator, and show a case where the switch contacts 6 are connected in series and a case where the switch contacts 6 are connected in parallel, respectively.

In FIG. 3, 6 is a temperature detection element, 6 is a contact of a safety switch activated by the heated object, 12 is a voltage comparator that compares and outputs the voltage of the temperature detection element 5, 13 is a relay coil, and 14 is a transistor. It constitutes a drive circuit. Note that when there is an object to be heated, the contact 6 is closed.

In this circuit, when the resistance value of the temperature detection element 5 drops below a predetermined value due to abnormal temperature, or when the object to be heated is removed and the safety switch contact 6 opens, the transistor 14 turns off and the relay Open contact 2 and turn on electric heating element 1
Stop energizing.

FIG. 4 shows a configuration in which safety switches are connected in parallel to the reference circuit, and when there is an object to be heated, the contacts e of the safety switches are connected to open.

Similarly in this circuit, when the heated object 12 is removed and the contact 6 is closed, the output of the voltage comparator 12 becomes low level, the transistor 14 is turned off, the relay contact 2 is opened, and the electric heating element 1 is energization is stopped.

Effects of the Invention As is clear from the description of the embodiments above, 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, so the operating temperature of the electric heating element decreases. Not only can the lifespan be extended, but also the adverse effects of temperature on the main body can be eliminated.

In particular, there is a switch in the temperature detection circuit, so if there is a malfunction in the circuit, it will turn on even if there is no object to be heated, so you can know in advance that the safety device will not operate. Greater safety.

[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), 4... Temperature detection circuit, 6...
... Temperature detection element, 6 ... Safety switch contact, 7 ... Reference circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
figure

Claims (1)

[Claims] A cooking device such as an electric range having an electric heating element,
A temperature detection element, a temperature detection circuit that compares and outputs the detected voltage, a drive circuit driven by the output, a power control means connected in series to the electric heating element, and a temperature detection circuit placed on the top of the electric heating element. A safety device for an electric cooker has a safety switch that is activated by an object to be heated, and a contact point of the safety switch is connected in parallel or in series to a reference circuit of a temperature detection circuit.