JPH02312178A - Heating cooker - Google Patents

Abstract

PURPOSE:To surely detect abnormal electricity transmission conditions without being affected by external factors so as to cut off the electricity transmission passage of an electric heater by interposing in the electricity transmission passage of an electric heater a current fuse for fusing by means of continuous electricity transmission of the electric heater. CONSTITUTION:The serial circuit of an electric heater 5 and a thylister (switching element) 18 is connected between power source lines 16, 17 to form the electricity transmission passage 19 of the electric heater 5. Also, the current fuse 15 is interposed in the electricity transmission passage 19 of the electric heater 5. In this case, the electric heater 5 is heated with a capacity of 1/3 of rated capacity during normal operation for extracting coffee, and, when electricity is continuously transmitted to the electric heater 5, the electric fuse 15 is immediately fused to cut off the electricity transmission passage 19 of the electric heater 5. Abnormal electricity transmission conditions of the electric heater 5 are thus immediately detected to cut off electricity transmission to the electric heater 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a cooking device that detects an abnormal energization state of an electric heater for cooking.

(Prior art) A heating cooker, such as a siphon coffee extractor, supplies water to a lower container, stores coffee powder in an upper container, and generates hot water by heating the lower container with an electric heater. The hot water is raised to the upper container by steam pressure based on boiling and mixed with coffee powder, and the temperature rise in the upper container due to the rising of the hot water to the upper container is detected by a temperature sensor and sent to the electric heater. It is configured to turn off the power. Thereafter, when the lower container is cooled by the electric heater stopping generating heat, the hot water mixed with the coffee powder in the upper container descends into the lower container, thereby extracting coffee liquid.

However, if a switching element such as a triac connected in series with the electric heater to turn it on or off remains on due to a short-circuit failure, or a control means such as a microcontroller that controls the switching element If the switching element fails and the switching element remains on, the electric heater is energized and continues to generate heat, creating a dangerous situation.

For this reason, conventionally, a temperature fuse is configured to detect an abnormal temperature rise in the lower container due to excessive heating of the electric heater and blow it out, thereby cutting off the energizing path of the electric heater.

(Problems to be Solved by the Invention) In the conventional configuration, when the set temperature for blowing the temperature fuse is set high, there is a problem that it takes time to blow the temperature fuse even if an abnormal temperature rise occurs due to abnormal energization of the electric heater. Conversely, if the set temperature for blowing the temperature fuse is lowered, a situation may occur in which the temperature fuse blows even though there is no abnormal temperature rise. Moreover, the temperature fuse is wind 1
Since it is easily affected by external factors such as ambient temperature, reliable operation cannot be expected.

The present invention has been made in view of the above circumstances, and its object is to provide heating that can reliably detect an abnormal energization state of an electric heater without being influenced by external factors and cut off the energization path of the electric heater. Cooking equipment is provided.

[Structure of the Invention] (Means for Solving the Problems) The cooking device of the present invention is provided with a control means for controlling a switching element so as to energize the electric heater for heating intermittently so that it generates heat below its rated capacity. , is characterized in that a current fuse that is blown by continuous energization of the electric heater is interposed in the energization path of the electric heater.

(Function) According to the heating cooker of the present invention, if the switching element or the control means fails and the switching element remains in the on state, the electric heater changes from the intermittent energization state to the continuous energization state. It begins to generate heat at its rated capacity, and the current fuse immediately blows, cutting off the energized path of the electric heater.

(Example) Hereinafter, an example in which the present invention is applied to a siphon-type coffee extractor will be described with reference to the drawings.

First, the overall configuration will be described according to FIG. The vessel body 1 is constructed in an abbreviated shape consisting of a base 2 and a support 3. A heating plate 4 is arranged on the upper part of the base 2, and an electric heater 5 is arranged on the lower part of this heating plate 4. The lower container 6 placed on the heating plate 4 has a flask shape, and the upper container 7 is placed in the upper opening thereof. The upper container 7 has a substantially spherical shape, and a substantially funnel-shaped water pipe 7 a is formed at its lower part, and the water pipe 7 a is inserted into the lower container 6 . A filter 8 is removably attached to the upper opening of the water pipe 7a in the upper container 7. A thermistor 9, which is a temperature sensor, is elastically supported in the upper part of the support column 3 in the form of a strip that projects laterally. in contact with the lower side of the Furthermore, an electronic circuit unit 10 is disposed within the support column 3. This electronic circuit unit 16 includes an electronic circuit shown in FIG. Further, the electronic circuit unit 10 is provided with a temperature fuse 11.
1 detects the temperature in the vicinity of the lower container 6 placed on the heating plate 4 and melts when the temperature becomes abnormal. And at the bottom of the pillar 3 there is an on/off switch 1
2 and a pilot lamp 13 are provided. The on/off switch 12 is a push button switch that is turned on only while the suppression operation is being performed.

Now, the configuration of the electronic circuit will be described according to FIG.

The power plug 14 is plugged into a power outlet (not shown), and one terminal thereof is connected to a power line 16 via a temperature fuse 11 and a current fuse 15 in series, and the other terminal is connected to a power line 17. ing. A series circuit of an electric heater 5 and a triac 18 serving as a switching element is connected between the power supply lines 16 and 17, thereby forming a current conduction path 19 for the electric heater 5. That is, the current fuse 15 is interposed in the energizing path 19 of the electric heater 5, and is designed to melt when the electric heater 5 is continuously energized and generates heat at its rated capacity.

The constant voltage enclosure 20 includes a step-down transformer 21 . The primary coil 21a of the step-down transformer 21 is connected to the power line 16.1.
The secondary coil 21b is connected between both AC input terminals of a full-wave rectifier circuit 22 formed by bridge-connecting diodes 22a to 22d. The positive (+) side output terminal of this full-wave rectifier circuit 22 is connected to the power supply line 17, the negative (=) side output terminal is connected to the power supply line 23, and an electrolytic capacitor 24 is connected between the power supply lines 17 and 23. is connected. In addition, in the PNP type transistor 25 that acts as a regulator, its collector is connected to the power line 23, its emitter is connected to the power line 26, and its base is connected to the power line 17 via a constant voltage diode 68. It is connected to the power supply line 23 via a resistor 27. And, there is an electrolytic capacitor 2 between the power lines 17 and 26.
8 and a capacitor 29 are connected.

A microcomputer 30 serving as a control means controls an electric heater 5
It controls the power supply/disconnection of the power supply boat vDD.
and VSS are connected to power lines 17 and 26, respectively. Further, in the microcomputer 30, the output port 01 is connected to the power line 17 via the pilot lamp 13 and the resistor 31 in series, and the input port 01 is connected to the power line 17 via the on/off switch 12. Connected to the power supply line 26 via the resistor 32, output capo)
02 is connected to the gate terminal of the triac 18 via a resistor 33.

The oscillation circuit 34 provides clock pulses to the microcomputer 30 and includes a crystal oscillator 35. One terminal of this crystal oscillator 35 is connected to the input port X1 of the microcomputer 30 and also to the power supply line 26 via a capacitor 36, and the other terminal is connected to the input port X1 of the microcomputer 30 via a resistor 37. Connected to output boat X2 and capacitor 38
It is connected to the power supply line 26 via. Then, the input port X and the output port X2 of the microcomputer 30
A resistor 39 is connected between them.

A series circuit of a thermistor 9 and a resistor 40 is connected between the power lines 17 and 26, and a common connection point of the thermistor 9 and the resistor 40 is connected to the input port VR of the microcomputer 30. A detection circuit 41 is configured.

The power-on reset circuit 42 is connected to the microcomputer 3
0. That is, a series circuit of a resistor 43, 44 and a constant voltage diode 45 is connected between the power supply lines 17, 23, and a common connection point of the resistors 43 and 44 is connected to the base of a PNP type transistor 46. In this transistor 46, the emitter is connected to the emitter of a PNP type transistor 47 and also connected to the power supply line 17 via a resistor 48, and the collector is connected to the base of the transistor 47 and the power supply line 17 via a resistor 49. It is connected to line 26. Also, the transistor 47
The collector of is connected to the power supply line 2 through resistors 50 and 51 in series.
6, and a common connection point of resistors 51 and 52 is connected to the base of an NPN transistor 52. The collector of the transistor 52 is connected to the reset port R of the microcomputer 30 and also to the power line 17 via a resistor 53, and the emitter is connected to the power line 26.

The zero cross circuit 54 includes a bias resistor 55a.

The transistor 55 has an NPN type transistor 55b. In this transistor 55, the collector is a resistor 5
6 to the power line 17, and the emitter is connected to the power line 2
6. There is a resistor 57 between the power lines 16 and 17.
．． 58 series circuits are connected, and a common connection point of resistors 57 and 58 is connected to the emitter of a PNP type transistor 59 and the base of a PNP type transistor 60.

Further, the base of the transistor 59 is connected to the emitter of the transistor 60 and then to the power supply line 17, and the collectors of both transistors 59 and 60 are connected in common and connected to the bias resistor 55a of the transistor 55. There is. Further, the collector of the transistor 55 is connected to the base of an NPN type transistor 61. and,
In the transistor 61, the emitter is connected to the power supply line 26, and the collector is connected to the input port 2 of the microcomputer 30 and also to the power supply line 17 via the resistor 62.

The notification circuit 63 includes a PNP type transistor 64 having bias resistors 64a and 64b. In this transistor 64, the emitter is connected to the power supply line 17, the collector is connected to the power supply line 26 via the resistor 65,
The bias resistor 64a is connected to the output port 03 of the microcomputer 30. A buzzer 66 serving as an alarm is connected in parallel to the resistor 65.
A diode 67 is connected in parallel with .

Next, the operation of this embodiment will be explained with reference to FIG. 3.

Now, when the power plug 14 is inserted into the power outlet and connected, as shown in FIG. 3(a), the commercial power supply voltage VI! is 100 volts! is applied to the primary coil 21a of the step-down transformer 21 in the constant voltage circuit 20, and the secondary coil 21b
A low-voltage AC voltage is induced in the full-wave rectifier circuit 2.
2, and is smoothed by a smoothing capacitor 24. The DC voltage, which is the voltage between the terminals of the smoothing capacitor 24, is turned on and off by the transistor 25, smoothed by the smoothing capacitors 28 and 29, and is applied between the power supply lines 17 and 26 as a constant DC voltage.

Here, when the power plug 14 is first inserted and connected to the power outlet, the DC voltage, which is the voltage between the terminals of the smoothing capacitor 24, has not yet reached a predetermined value, so that the voltage regulator diode 45 of the power-on reset circuit 42 is in a non-conducting state. As a result, the transistor 46 is off, the transistor 47 is on, and the transistor 52 is on, with its collector potential at a low level. Since the low level signal of this transistor 52 is applied to the reset port R of the microcomputer 30, the microcomputer 30 is placed in a reset state. Thereafter, when the DC voltage of the smoothing capacitor 24 of the constant voltage circuit 20 reaches a predetermined value, the constant voltage diode 45 of the power-on reset circuit 42 becomes conductive, so that the transistor 46 is on and the transistor 47 is off. As a result, the transistor 52 is turned off and its collector potential becomes high level.

As a result, the microcomputer 30 enters a set state, is initialized, and enters a standby state for starting operation. As a result, the microcomputer 30 sets the output port 01 to a low level, and the pilot lamp 13 is energized and lights up. On the other hand, since the commercial power supply voltage vE is also applied to the series circuit of the resistors 57 and 58 of the zero cross circuit 54, the transistor 55 is connected to the positive (+) of the commercial power supply voltage V.
and turns on near the negative (-) zero point (0 volts),
Therefore, transistor 61 is turned on near its zero point. As a result, the collector potential of the transistor 61 repeats high level (5 volts) and low level (0 volts) as shown in FIG. will be given to

After supplying water for the desired number of people into the lower container 6 and storing coffee powder for the desired number of people in the upper container 7, the lower container 6 is mounted on the heating plate 4. Then, when the on-off switch 12 is suppressed and turned on, the resistor 32
A voltage is generated between the terminals of the microcomputer 30, and this voltage is applied to the input port 11 of the microcomputer 30 as an on signal. Therefore, the microcomputer 30 counts the zero cross signal S54 given to the input port I2, and outputs the low level for 2 power counts and the high level for the next 4 power counts from the output port 02 as shown in FIG. 3(C). A repeating gate signal 33G is output. That is, the gate signal S3Q has a duty ratio of 1/3 with respect to the low level. As a result, the triac 18 is turned on during the low level period of the gate signal 830 and turned off during the high level period of the gate signal 830, and the applied voltage v5 to the electric heater 5 is reduced as shown in FIG.
), the IHz energization of the commercial power supply voltage V and the next 2Hz energization result in 1/3, and the electric heater 5 generates heat at less than the rated capacity, that is, 1/3 of the rated capacity.

In this case, it goes without saying that the rated capacity of the electric heater 5 is set to a capacity that can boil the water in the lower container 6 in the same time as the conventional one even if it generates heat at 1/3, for example, three times the capacity of the conventional one. It is.

Then, the water in the lower container 6 is heated by the heat generated by the electric heater 5, and then boils. When hot water is generated in the lower container 6 and boils, the steam pressure in the lower container 6 increases, and the hot water rises through the water pipe 7a and flows into the upper container 7.
and mixed with coffee powder. Here, when hot water is supplied into the upper container 7, the upper container 7
temperature starts to rise, the thermistor 9 detects this and decreases its resistance value. Therefore, the voltage between the terminals of the resistor 40 connected in series with the thermistor 9 becomes a predetermined value, and the microcomputer 3o detects this and outputs the output port 0.
The gate signal 83G from 2 is maintained at a high level. As a result, the thyristor 18 remains off, and the electric heater 5 is cut off and stops generating heat. After that, after 2 to 3 minutes, the lower container 6 is naturally cooled and the internal vapor pressure decreases, so that the hot water mixed with the coffee powder in the upper container 7 falls into the lower container 6 due to its own weight. Become. When the coffee powder falls, it is filtered by the filter 8, so that only the coffee liquid is extracted and stored in the lower container 6. At this point, the microcomputer 30 brings the output port 03 to a low level for a short period of time (several seconds), so that the transistor 64 turns on and causes the buzzer 66 to sound.

Furthermore, after the microcomputer 30 sets the output port O9 to a low level, the gate signal S30 of the output port 02 is output at a capacity that is even smaller than during the extraction operation in which the electric heater 5 generates heat at 1/3 of the rated capacity. The high-level and low-level green return signals that generate heat are used, and the heat-retaining operation is performed. Then, when the on/off switch 12 is suppressed again and turned on, the voltage between the terminals of the resistor 32 is now applied as a stop signal to the input port 11 of the microcomputer 30, and the microcomputer 3o returns to its initial state. It becomes like this.

By the way, if the thyristor 18 is short-circuited and remains on, or if the microcomputer 30 fails and the gate signal 830 is set to low level, the thyristor 1
8 remains in the on state, the commercial power supply voltage V8 is directly applied to the electric heater 5, and the electric heater 5 is continuously energized. In this case, the current fuse 15 is set to blow with the current generated when the electric heater 5 generates heat with a capacity slightly larger than 1/3 of its rated capacity. If an abnormal energization state occurs in which the power supply voltage VB is applied, the current fuse 15 immediately blows out, cutting off the energization path 19 of the electric heater 5.

As described above, according to this embodiment, under normal conditions, the electric heater 5 is made to generate heat at 1/3 of its rated capacity to perform coffee extraction, and the thyristor 18 is activated due to a short-circuit failure of the thyristor 18 or a failure of the microcomputer 30. When the electric heater 5 remains on and is continuously energized and generates heat at its rated capacity, the current fuse 15 immediately blows and cuts the energization path 19 of the electric heater 5, thereby preventing abnormal energization of the electric heater 5. When a condition occurs, it can be detected immediately and the electric heater 5 can be cut off.Moreover, unlike conventional temperature fuses, the current fuse 5 is immune to the influence of external factors such as wind 1 and ambient temperature. Since it does not receive any damage, the fusing operation can be performed reliably.

Incidentally, in the above embodiment, the electric heater 5 is made to generate heat at 1/3 of its rated capacity to perform the coffee extraction operation, but the point is that the electric heater 5 is not limited to this, but the point is that the electric heater 5 is made to generate heat at a capacity less than the rated capacity. What is necessary is to adopt a configuration in which power supply/disconnection control is performed to achieve this.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, but can be applied not only to siphon coffee extractors but also to general cooking devices that use electric heaters for heating. Of course, modifications may be made as appropriate without departing from the above.

[Effects of the Invention] As explained above, the cooking device of the present invention causes the electric heater for cooking to generate heat at less than the rated capacity under normal conditions, and when the electric heater generates heat at the rated capacity, melts the current fuse. Since the energizing path of the electric heater is cut off, if an abnormal energizing state of the electric heater occurs due to a failure of the switching element or control means, this can be reliably detected and the energizing path of the electric heater can be cut off. This has an excellent effect.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, with FIG. 1 being a wiring diagram of an electronic circuit, and FIG. 2 being a partially cutaway side view of the overall configuration.
FIG. 3 is a waveform diagram of each part for explaining the operation. In the drawing, 1 is a container body, 5 is an electric heater, 6 is a lower container, 7
is the upper container, 9 is the thermistor, 15 is the current fuse, 1
8 is Sirisk (switching element), 19 is a circuit,
30 indicates a microcomputer (control means). Applicant Toshiba Corporation Agent Patent Attorney Tsuyoshi Sato Figure 2

Claims (1)

[Claims] 1. An electric heater for cooking, a control means for controlling a switching element to energize intermittently so that the electric heater generates heat at less than its rated capacity, and a continuous energization of the electric heater that is interposed in the energization path of the electric heater. A heating cooker comprising a current fuse that is blown by a current fuse.