JPH0128570B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to household cooking appliances such as jiyar rice cookers, and in particular to a configuration that increases the reliability of the configuration of power control means of these cooking appliances. That is.

Conventional configuration and its problems In recent years, cookers such as jar rice cookers have been equipped with drive control circuits equipped with microcomputers to perform detailed power control according to a certain program, which improves cooking performance. Attempts are being made to improve.

Hereinafter, a conventional cooking device as described above will be explained with reference to the drawings.

FIG. 1 specifically shows a jar rice cooker equipped with a microcomputer as an example of a conventional cooker. In Figure 1, 1 is a power plug, 2 is a power switch, 3 is a temperature fuse, 4 is a line capacitor for noise reduction, 5 is a lower heater with a high power installed at the inner bottom of the main body, and 6 is an inner surface of the main body. 7 is a lid heater provided on the bottom surface of the lid, 8 is a side heater provided on the bottom of the lid;
9 is a relay contact, 9 is a relay coil, 10 is a heat retention triax that controls the lower heater 5 connected in series with a parallel circuit of a side heater 6 and a lid heater 7, and 11 is a microcomputer. This output turns transistors 12 and 13 on and off to drive the relay and triac 10. 14 is an output display section, 15 is a pot temperature input section consisting of a heat-sensitive element that contacts the pot, and 16 is a thermoswitch for detecting the completion of rice cooking. In addition, resistance 1
7, a diode 18, a resistor 19, a Zener diode 20, and electrolytic capacitors 21 and 22 constitute a power source for this drive control circuit.

Regarding the jiya rice cooker configured as above,
The operation will be explained below.

First, when cooking rice, when the thermoswitch 16 is turned on, the microcomputer 11 enters the rice cooking mode, and while turning on and off the relay contact 8 according to the signal from the pot temperature input section 15, the process of absorbing rice water and automatically determining the amount of rice to be cooked is performed. After the steps of , etc., the lower heater 5 is energized and rice is cooked. When the rice cooking is finished, the thermo switch 16 is shut off, and the microcomputer 11 detects the end of the rice cooking mode, turns off the relay contact 8, stops energizing the lower heater 5, and finishes the rice cooking. Thereafter, the heating mode is shifted to the heat retention mode through an additional heating and uneven heating process in which only the lower heater 5 is temporarily energized.

In the heat retention mode, the triack 10
It is turned on and off by the signal from the pan temperature input section 15, and the lower heater 5, side heater 6, and lid heater 7 are energized.
It performs a heat-retaining operation.

However, in the above configuration, since the on/off control of the lower heater 5 is performed by the contact 8 of the relay, it is necessary to increase the capacity of the contact 8 of the relay, and when the life of the contact 8 of the relay ends, the contact If it were welded, a large current would be continuously applied and the temperature fuse would be activated.

In addition, using power semiconductors for the relay will improve the above drawbacks, but cooling fins will be required, increasing costs and making the parts larger, making it difficult to incorporate them into the cooker. There were flaws.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks and provides a cooking appliance equipped with a control means that can control a large current, has high reliability, and can be realized at low cost.

Structure of the Invention In order to achieve the above object, the cooking appliance of the present invention comprises a power control means by a parallel circuit of a relay and a triax, the power control during heating operation is performed by the parallel circuit, and the power control means during heating operation is performed by the parallel circuit. The power control is performed only by the tri-attack of the parallel circuit.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be specifically described with reference to a jar rice cooker. A main body, a lid that can be opened and closed on the top of the main body, a pot that is removably housed in the main body, a lower heater provided on the inner bottom of the main body, a side heater provided on the inner surface of the main body, and a lid. A parallel circuit of the lid heater and side heater, a lower heater, and a parallel circuit of a relay and triax are connected in series to both ends of the power supply. , the common side of the thermo switch that detects the completion of rice cooking should be on the power line side between the connection point with the parallel circuit of the lid heater and side heater and a power line that is separate from the power line connected to the relay contact. In addition, the other contacts of the thermoswitch were connected to the input terminal of the drive circuit of the power control means equipped with a microcomputer, so the circuit was connected to the input terminal of the drive circuit of the power control means. It is structured as follows. In addition, the method of outputting the drive signal from the microcomputer to the power control means is as follows: When the drive signal is on, the triack on signal and the relay on signal are generated almost simultaneously, and when the drive signal is off, The off signal of the triack is slightly longer than the operating time of the relay, and is generated later than the off signal of the relay.

With this circuit configuration, when only the high-power heater is energized during rice cooking, power can be controlled using a parallel circuit of relays and triaxes, resulting in low-cost and highly reliable cooking. It serves as a vessel.

Fig. 2 shows the electric circuit of the jar rice cooker. 30 is a power plug, 31 is a power switch, 32 is a temperature fuse, 33 is a capacitor for noise reduction, 34 is a triac, 35 is a relay contact, 3
6 is a lower heater, 37 is a side heater, 38 is a lid heater, and 39 is a thermoswitch.

A contact 39b of the thermoswitch 39 is input to the base of a transistor 42 via a resistor 40 and a diode 41. 43 is a microcomputer, 44 is a pot temperature input section consisting of a heat-sensitive element on the side of the pot, 45 is an output display section, 46 is a relay coil,
47 and 48 are driving transistors, 49 is a Zener diode, 50 and 51 are diodes, and 5
2,53 is an electrolytic capacitor.

The operation of the electronic jar rice cooker configured as described above will be explained.

First, when cooking rice, turn on the thermo switch 39, and contact 39a of the thermo switch 39.
The power control means and the lower heater 36 are connected to a power source that connects the common side 39c and the common side 39c. Also, contact 3
9b is disconnected from the power supply line, the base current of the transistor 42 disappears, the input signal of the microcomputer 43 becomes low level, and the microcomputer enters the rice cooking mode. Based on the signal from the pot temperature input section 44, the microcomputer 43 turns on and off the transistors 47 and 48 according to the rice cooking program, and as a result, the relay 35 and the tryout 3 of the power control means are turned on and off.
4, the rice cooking progresses while performing steps such as turning on and off, energizing the lower heater 36 to absorb water from the rice, and automatically determining the amount of rice to be cooked.

The parallel circuit between the relay contact 35 of the power control means and the triax 34 operates as follows. Third
4 shows the operating waveforms. When the triac 34 and the relay contact 35 are simultaneously fired, the triac 34 first becomes conductive and current flows only to the triac 34. In FIG. 3, 60 is the voltage across the power control means, the triac is turned on from 61, and 62 is the ON voltage of the triac. On the other hand, since the relay coil 46 is also driven as shown in figure 66,
The relay contact 35 closes with a delay of msec. When the relay contact 35 closes, as shown from point 63, the voltage drop across the power control means is almost zero, and all current flows only through the relay contact 35, as shown at point 63. Then, the current is switched to the relay contact 35.

Next, when the power control means is turned off, as shown in figure 70 in FIG. 4, the relay coil 46 first stops driving, and then the contacts open after a delay of time (T2) shown in figure 72. Then, the current is switched to the triac 34 side, and an on-voltage 73 is generated across the triac 34. Then time T ₁
After the lapse of time, the gate current of the triac 34 is stopped as shown at 74 in FIG. 4, so that the power supply voltage 75 is restored across the power control means.

In this way, the relay contact 35 and the triax 34
By using a parallel circuit with the relay contact 35 as a power control means, a large current flows through the relay contact 35, but when turning on and off, the voltage is lower than the on-voltage of the triac 34 (approximately
1V), no arc occurs and the reliability of the relay contact 35 is greatly improved.

As described above, when the lower heater 36 is energized and rice cooking is completed, the thermo switch 39 switches to the contact 39b side, and the microcomputer 43 has the following information:
The rice cooking is completed through the transistor 42, and after that, the rice cooker goes through additional cooking and shading steps, and then shifts to the warming operation mode.

During heat retention, the lower heater 36, the parallel circuit of the side heater 37 and the lid heater 38 are connected in series, and the power can be controlled only by the triax 34.

Therefore, when energizing the lower heater 36 during the cooking operation, by using a power control means in which a relay and a triax are connected in parallel,
In addition to being a highly reliable cooking appliance, the relay contacts can be relatively small and the tri-axes can also be constructed at a low cost, since they can draw only a small current.

Effects of the Invention As described above, according to the present invention, since the relay and the triax are connected in parallel to prevent arcing at the relay contacts, it is possible to provide a high-reliability high-power control means at a low cost. This makes it possible to provide a highly reliable cooker with the following features.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram of a conventional jiya rice cooker, Fig. 2 is an electric circuit diagram of a jiya rice cooker according to an embodiment of the present invention, and Fig. 3 is an electric circuit diagram of a jiya rice cooker according to an embodiment of the present invention. The operating waveforms shown in FIG. 4 are the waveforms when the device is off. 34...Triack, 35...Relay contact,
46...Relay coil.

Claims (1)

[Claims] 1. A cooking device in which the power control means is constituted by a parallel circuit of a relay and a triax, power control during heating cooking operation is performed by the parallel circuit, and power control during warming operation is performed only by the triax of the parallel circuit. vessel.