JPH09444A - Electric pot - Google Patents

Abstract

PURPOSE: To provide a prescribed heat insulation temperature even when a room temperature and a power supply voltage are low by providing a rectifying element, a heat insulation heater and a capacitor for smoothing serially connected to an AC power supply and a control element and a control circuit and respectively turning ON/OFF the control element corresponding to the both-terminal voltage of the smoothing capacitor. CONSTITUTION: When a temperature sensor 12 detects a water temperature lower than the heat insulation temperature, the control circuit 24 turns ON the control element 19 within a prescribed half wave. Thus, the energizing rate of the heat insulation heater 4 connected to the control element 19 becomes high, the water temperature rapidly rises and the prescribed heat insulation temperature is immediately obtained even when the room temperature or the power supply voltage is low. Also, when the temperature sensor 12 detects the water temperature higher than the heat insulation temperature, since the control element 19 is turned OFF when an AC power supply voltage is negative potential and both-terminal voltage of the heat insulation heater 4 is made small, the energizing rate becomes low and power consumption is suppressed. At the time of heat insulation, a stable voltage is supplied to respective circuits 27, 28 and 24 and the energizing rate to the heat insulation heater is changed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electric pot for boiling hot water.

[0002]

2. Description of the Related Art Conventionally, an electric pot of this type is disclosed in, for example, Japanese Patent Publication No. 6-85736. According to this publication, a relay and a water heater are connected in series to an AC power supply, and a control circuit is connected to the AC power supply via a power supply circuit. Then, in response to the input from the temperature sensor circuit, a control signal is output from the control circuit to the relay, and the boiling water heater and the warming heater are turned on. After that, when the hot water boils, the boiling water heater is turned off, and, for example, only the heat retaining heater with power consumption of 32 W is turned on.

[0003]

In such an electric pot, since a DC voltage having a relatively small voltage fluctuation and a low voltage is required for the control circuit, the power supply circuit described above is a transformer, a rectifying circuit and a smoothing circuit. And a constant voltage circuit, which has the first drawback that the cost becomes high.

Further, as described above, only the heat retention heater is continuously energized during heat retention, but when the room temperature or the power supply voltage decreases, the heat retention power becomes insufficient and the water temperature decreases, and a heat retention temperature (for example, 95 ° C.) is obtained. There is no second drawback. Further, when the water temperature further decreases and becomes equal to or lower than the automatic water boiling temperature (for example, 88 ° C.), the re-boiling operation is automatically repeated, and there is a disadvantage that wasteful power is consumed. Therefore, in consideration of such conventional drawbacks, the present invention provides an electric pot that has a low-cost power supply circuit and can immediately obtain a predetermined heat retention temperature even when the room temperature or the power supply voltage is low.

[0005]

In order to solve the above-mentioned problems, the present invention provides a rectifying element connected in series with an AC power source, a heat retaining heater, a smoothing capacitor, and a control element connected to the smoothing capacitor. And a control circuit connected in parallel to the smoothing capacitor, and the control circuit turns on the control element in accordance with the magnitude of the voltage across the smoothing capacitor,
It is something to turn off.

The present invention further desirably comprises a temperature sensor for detecting the temperature of the water in the electric pot and connected to the control circuit, wherein the temperature sensor detects a water temperature below or above the heat retention temperature. The control circuit turns the control element on and off within a predetermined half wave.

[0007]

As described above, in the present invention, the voltage from the AC power source is rectified by the rectifying element and lowered by the heat retaining heater, and the voltage across the smoothing capacitor rises. Thus, when the voltage across both ends becomes higher than the predetermined value, the control circuit turns on the control element, and the current flows through the control element, so that the charging current to the smoothing capacitor does not flow and the voltage across both ends drops. When the voltage between both ends becomes lower than the predetermined value, the control circuit turns off the control element, the smoothing capacitor is charged, and the voltage between both ends rises again. In this way, the control circuit turns on and off the control element so as to keep the voltage across the smoothing capacitor substantially constant, so that a substantially constant voltage can be supplied to the control circuit connected in parallel with the smoothing capacitor.

More preferably, the control circuit turns on the control element within a predetermined half wave when the water temperature sensor detects a water temperature below the heat retention temperature. Therefore, the energization rate of the warming heater connected to the control element becomes high, the water temperature rises rapidly,
Even if the room temperature or the power supply voltage is low, the predetermined heat retention temperature can be obtained immediately.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An electric pot according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of the electric pot, and FIG. 2 is a circuit diagram of the electric pot. In these drawings, the frame 1 has a cylindrical shape, and the container 2 has a bottomed cylindrical shape which is installed in the frame 1. The heater set 3 is composed of a warming heater 4 and a water heater 5 which are closely attached to the bottom of the container 2 for containing the content liquid (water or the like). The back cover 6 is fixed to the lower part of the frame 1, and a storage space 7 is provided between the back cover 6 and the bottom wall of the container 2.

The hot water supply pipe 8 has one end communicating with the container 2 and the other end led out of the frame 1. The hot water supply pump 9 is located in the path of the hot water supply pipe 8, is arranged and fixed in the storage space 7, and is driven by the DC motor 10. The storage box 11 stores control components for controlling the heat retention heater 4, the water heater 5, and the hot water supply pump 9.

The temperature sensor 12 is closely attached to the outer bottom surface of the container 2, the lid 13 is rotatably provided on the upper portion of the frame 1, and the hot water supply switch 14 is provided on the upper portion of the electric pot. The reboil switch 15 is provided at the bottom.

Next, the electric circuit will be described with reference to FIG. The surge absorber 16 and the condenser are connected in parallel to the AC power supply 17, and the relay contact 18 is a boiling water heater 5.
Are connected in series, and the series circuit is connected in parallel to the AC power supply 17.

The control element 19 is made of, for example, TRIAC, is connected in series with the heat retention heater 4, and the series circuit is connected in parallel with the AC power supply 17. The cathode of the Zener diode 20 is connected to the first lead wire 21 via the resistor 20a and the capacitor, and the anode thereof is the second lead wire 2
Connected to 2.

One of the intermediate points of the resistor and the capacitor is connected to the gate of the control element 19 and the other is connected to the emitter of the transistor 23. The collector of the transistor 23 is grounded via a resistor, and one of the bases of the transistor 23 is connected to the first lead wire 2 via a resistor.
The other end of the base is connected to a terminal P1 of a control circuit 24 including a microcomputer or the like via a resistor.

One end of the smoothing capacitor 25 is connected to one end of the control element 19, that is, the first lead wire 21, and the other end of the smoothing capacitor 25 is connected to the second lead wire 22. The rectifying element 26 is, for example, a diode,
Its anode is connected to the other end of the smoothing capacitor 25, that is, the second lead wire 22, and its cathode is connected to the other end of the control element 19. In this way, the AC power supply 17
, One end of the smoothing capacitor 25, the rectifying element 26, the heat retaining heater 4, and the other end of the AC power supply 17 are connected in series to form a closed circuit.

The hot water supply switch 14 and the motor circuit 27 are connected in series, and both ends of the series circuit are connected to the first lead wire 2 respectively.
1 and the second lead wire 22. Relay circuit 2
8 is a relay and a diode connected in parallel,
One end of the relay circuit 28 is connected to the collector of the transistor 29, and the other end is connected to the second lead wire 22.

The emitter of the transistor 29 is connected to the first lead wire 21, the base of the transistor 29 is connected to the first lead wire 21 via a resistor, and its base is connected to the terminal P2 of the control circuit 24 via a resistor. Has been done.

The voltage detection circuit 30 comprises a transistor 31, a Zener diode 32, etc.
The emitter of is connected to the first lead wire 21, and the collector is grounded via a resistor. The base of the transistor 31 is a Zener diode 32 via a resistor.
Of the Zener diode 32, and the anode of the Zener diode 32 is connected to the second lead wire 22. Further, the collector of the transistor 31 is connected to the control circuit 2 via a resistor.
4 is connected to the terminal P3.

As described above, the first power supply circuit 33 is composed of the heat retaining heater 4, the control element 19, the smoothing capacitor 25, the rectifying element 26 and the like. In addition, the second power supply circuit 34
Is composed of a Zener diode 35, a transistor 36, a capacitor 37, and the like. That is, the cathode of the Zener diode 35 is connected to the first lead wire 21, the anode is connected to the base of the transistor 36, and the anode thereof is connected to the second lead wire 22 via a resistor. The emitter of the transistor 36 is shared with one end of the capacitor 37 and is grounded. The other end of the capacitor 37 is connected to the first lead wire 21.

One end of the temperature sensor 12 is connected to the lead wire 38, and the other end of the temperature sensor 12 is connected to the terminal P4 of the control circuit 24 via the resistor 39. The other end of the temperature sensor 12 and the midpoint of the resistor 39 are grounded via the resistor 40.

The zero-cross detection circuit 41 comprises, for example, a diode 42, a resistor 44 and a transistor 45,
The anode of the diode 42 is connected to the AC power supply 17 via a resistor.
Is connected to the other end, and its cathode is connected to the lead wire 38 via the lead wire 43. The resistor 44 is connected in parallel to both ends of the diode 42, the emitter of the transistor 45 is connected to the lead wire 43, and the base thereof is connected to the anode of the diode 42. The collector of the transistor 45 is grounded via a resistor, and its collector is connected to the terminal P5 of the control circuit 24 via another resistor.

One end of the lead wire 38 is connected to the first lead wire 21, and the other end of the lead wire 38 is the terminal P of the control circuit 24.
6 and P7. Then, the first lead wire 21
Is connected to a terminal P8 via a heat retention lamp 46 and a resistor, to a terminal P9 via a water heating lamp 47, and to a terminal P10 via a reboil switch 15. These parts constitute the electric pot of this embodiment.

Next, the operation of this electric pot will be described with reference to FIGS. 3 is a flowchart of the control circuit 24, and FIG. 4 is a continuation of FIG. In these figures, first, water is put in the container 2 and the power plug of the electric pot is inserted into a power outlet (none of which is shown).

When the AC power supply 17 has a positive potential, a current flows from the AC power supply 17 to the AC power supply 17 through the first lead wire 21, the smoothing capacitor 25, the second lead wire 22, the rectifying element 26 and the heat retaining heater 4. As a result, the voltage across the smoothing capacitor 25 starts rising. However, when the voltage across the smoothing capacitor 25 is still low, the control element 19 remains off.

Next, when the voltage across the smoothing capacitor 25 rises to reach the Zener voltage of the Zener diode 20, for example, 15 V or more, a current flows through the path of the resistor 20a, the Zener diode 20 and the rectifying element 26, and the control element 19 Turns on.

As a result, a current mainly flows through the control element 19 and almost no current flows through the smoothing capacitor 25, so that the voltage across the smoothing capacitor 25 drops.
When the voltage across the smoothing capacitor 25 becomes equal to or lower than the Zener voltage of the Zener diode 20, the gate current to the control element 19 stops flowing, and the control element 19 moves to the next zero cross point (AC voltage of the AC power supply 17 changes from positive potential to zero potential). It turns off at the point of changing to.

In this way, the period (reset period) from when the power is turned on to when the control circuit 24 starts up is about 0.1 to 0.5 seconds, and the smoothing capacitor 25 and the rectifier are rectified during this period. The series circuit including the element 26 and the heat retention heater 4 and the series circuit including the control element 19 and the heat retention heater 4 are sequentially turned on. As a result, the voltage across the smoothing capacitor 25 is maintained substantially constant.

Next, when the above reset period ends,
The operation starts under the control of only the control circuit 24. When the temperature sensor 12 detects that the water temperature in the container 2 of the electric pot is "low temperature", the boiling water operation of the control circuit 24 starts in FIG.

First, the control circuit 24 determines "whether or not negative zero positive zero cross" (step S1). That is,
The zero-cross detection circuit 41 detects that the power supply voltage generated from the AC power supply 17 has changed from a negative potential to a zero potential, and outputs the signal to the terminal P5 of the control circuit 24.

When the above determination is YES (step S1), it is determined "P3 is Hi or not" in FIG. 3 (step S2). That is, the control circuit 24 reads the potential of the terminal P3 connected to the voltage detection circuit 30. That is, in FIG. 2, the voltage detection circuit 30 sets the Zener voltage of the Zener diode 32 to about 11 V, which is lower than the Zener voltage of the Zener diode 20.

As a result, when the voltage across the smoothing capacitor 25 is about 11 V or more, a current flows between the transistor 31 and the Zener diode 32, turning on the transistor 31. Then, the “Hi” signal is input to the terminal P3 of the control circuit 24, and when the voltage across the Zener diode 32 is less than about 11 V, the transistor 31 is turned off and the “Lo” signal is input to the terminal P3. .

In this way, when the control circuit 24 is released from the reset state, the voltage across the smoothing capacitor 25 is about 15V. Therefore, the terminal P3 is at "Hi" level, and the control circuit 24 determines that the voltage across the smoothing capacitor 25 is about 11V or higher.

Then, the control circuit 24 asks "Is P3 Hi?"
When it is determined to be ES (step S2), "the control element is turned on at a positive potential" (step S3). That is, in FIG. 2, the control circuit 2 indicates that the voltage across the Zener diode 32 is about 11 V or more and the "Hi" signal is input to the terminal P3.
4 determines, the control circuit 24 outputs a "Lo" signal (trigger pulse) to the terminal PI within the half wave in which the AC voltage is at a positive potential.

As a result, the transistor 23 turns on,
A gate current flows through the control element 19, and the control element 19 turns on. Therefore, no current flows to the smoothing capacitor 25 side, and the voltage across the smoothing capacitor 25 starts to decrease. Further, when the control circuit 24 determines “NO in P3 is Hi” (step S2), the control circuit 24 “turns off the control element at a positive potential” (step S4).

That is, in FIG. 2, the voltage across the Zener diode 32 becomes less than about 11 V, and the voltage at the terminal P3 becomes "L".
When the "o" signal is input, the trigger signal is not output to the terminal P1. As a result, the transistor 23 turns off and the control element 19 also turns off. Therefore, the smoothing condenser 2
The current flows to the 5 side, and the voltage across the smoothing capacitor 25 rises.

Next, the control circuit 24 "turns on the control element at a negative potential" in order to fully energize the heat retention heater 4 during boiling (step S5). That is, in FIG. 2, the control circuit 24 controls the terminal P within the half wave in which the AC voltage is at a negative potential.
The “Lo” signal (trigger pulse) is output to 1. As a result, the transistor 23 is turned on, the control element 19 is turned on, and the heat retention heater 4 is turned on (energized).

Then, "the water heater is turned on" (step S6). That is, in FIG. 2, the control circuit 24
The "Lo" signal is output from the terminal P2 of the transistor, the transistor 29 is turned on, the relay circuit 28 is turned on, and the relay contact 1
8 is turned on, and the water heater 5 is turned on.

Next, when it is determined that the water temperature detected by the temperature sensor 12 is "boiling" is NO (step S7), the process immediately returns to step S1 and the above steps S1 to S7 are repeated. Then, the control circuit 24 confirms "is it boiling?"
If it is determined, the process continues to A.

Then, as shown in FIG. 4, following "A", "the water heater is turned off" (step S8). With the above description, the water heating operation is completed. In this way, in the boiling water operation, the control circuit 24 turns on and off the control elements 19 in accordance with the magnitude of the voltage across the smoothing capacitor 25. That is, the control circuit 24 controls the control element 19 to be turned on or off at a positive potential of the alternating voltage depending on whether the P3 input corresponding to the voltage across the capacitor 25 is Hi or Lo.

Next, as in the case of the contents described with reference to FIG. 3, it is determined that "is negative zero positive zero crossing?" Is YES (step S
9), if "P3 is Hi" is determined to be YES (step S10), "the control element is turned on at a positive potential" (step S11). If "P3 is Hi" is determined to be NO (step S10), "the control element is turned off at a positive potential".
Yes (step S12).

Then, if it is judged YES whether "the temperature sensor is at or above the heat retention temperature" (step S13),
"The control element is turned off at a negative potential" (step S14).
That is, in FIG. 2, the control circuit 2 indicates that the water temperature detected by the temperature sensor 12 is equal to or higher than the heat retention temperature (for example, 95 ° C.).
4 determines that the AC voltage has a predetermined value (for example, a negative potential).
In the half wave, the control circuit 24 outputs a "Hi" signal to the terminal P1. As a result, the transistor 23 turns off,
The control element 19 is turned off and the heat retention heater 4 is turned off.

Next, "other processing" (step S15) is performed. That is, it is determined whether or not the reboil switch 15 has been pressed, lighting of the heat retention lamp 46, and determination of whether or not the cooking has been completed. Then, immediately before step S8,
Steps S8 to S15 are repeated.

In this way, when the temperature sensor 12 detects a water temperature equal to or higher than the heat retention temperature, the control circuit 24 turns off the control element 19 within a predetermined half wave. Therefore, the energization rate of the heat retention heater 4 connected to the control element 19 becomes low, and the water temperature gradually drops. Therefore, when the room temperature or the power supply voltage is relatively high, the predetermined heat retention temperature is maintained, and the power consumption of the heat retention heater 4 is suppressed.

Next, "whether the temperature sensor is warmer or higher" is NO.
If it is determined that (step S13), "control element is turned on at a negative potential" (step S16). That is, in FIG. 2, when the control circuit 24 determines that the water temperature detected by the temperature sensor 12 is lower than the heat retention temperature, the AC voltage is controlled within a predetermined half wave (for example, negative potential). The circuit 24 outputs a "Lo" signal (trigger pulse) to the terminal P1. As a result, the transistor 23 is turned on, the control element 19 is turned on, and the heat retention heater 4 is turned on. Next, another process (step S15) is performed, and steps S8 to S15 are repeated.

In this way, when the temperature sensor 12 detects a water temperature lower than the heat retention temperature, the control circuit 24 causes the control element 19 to move the control element 19 within a predetermined half wave (for example, within the period of the negative potential of the AC power supply).
Turn on. Therefore, the energization rate of the heat retention heater 4 connected to the control element 19 becomes high, the water temperature rises rapidly, and a predetermined heat retention temperature can be obtained immediately even if the room temperature or the power supply voltage is low.

When the temperature sensor 12 detects a water temperature higher than the heat retention temperature, when the AC power supply voltage has a negative potential,
Since the control element 19 is turned off and the voltage across the heat retention heater 4 is reduced, the energization rate is small and the power consumption is suppressed.

As described above, according to the structure of the electric pot of this embodiment, it is possible to supply a stable voltage to each of the circuits 27, 28 and 24 and to change the energization rate to the heat retention heater 4 during heat retention. It has the feature that it can.

[0048]

As described above, according to the present invention, the voltage from the AC power source is rectified by the rectifying element and stepped down by the heat retaining heater, and the voltage across the smoothing capacitor rises. When the voltage across both ends becomes higher than the predetermined value in this way, the control circuit turns on the control element, the current mainly flows through the control element, the charging current to the smoothing capacitor stops flowing, and the voltage across both ends drops.

When the voltage at both ends becomes lower than the predetermined value, the control circuit turns off the control element, the smoothing capacitor is charged, and the voltage at both ends rises again. In this way, the control circuit turns on and off the control element so as to keep the voltage across the smoothing capacitor substantially constant, so that a substantially constant voltage can be supplied to the control circuit connected in parallel with the smoothing capacitor.

More preferably, the control circuit turns on the control element within a predetermined half-wave when the water temperature sensor detects a water temperature below the heat retention temperature. Therefore, the energization rate of the warming heater connected to the control element becomes high, the water temperature rises rapidly,
Even if the room temperature or the power supply voltage is low, the predetermined heat retention temperature can be obtained immediately. As a result, the water temperature drops, and the automatic boiling temperature is lowered to prevent the automatic re-boiling operation from repeating,
Does not consume unnecessary power.

According to the present invention, when the temperature sensor detects a water temperature equal to or higher than the heat retention temperature, the control circuit turns off the control element within a predetermined half wave. Therefore, the energization rate of the heat retention heater connected to the control element becomes low, and the water temperature gradually decreases. Therefore, when the room temperature or the power supply voltage is high, the predetermined heat retention temperature is maintained and the power consumption of the heat retention heater is suppressed.

[Brief description of drawings]

FIG. 1 is a sectional view of an electric pot according to an embodiment of the present invention.

FIG. 2 is an electric circuit diagram of the electric pot.

FIG. 3 is a flow chart of the electric pot.

4 is a flow chart of the electric pot, FIG.
Is the continuation of.

[Explanation of symbols]

 4 Heat insulation heater 19 Control element 24 Control circuit 25 Smoothing condenser 26 Rectifying element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Arinaka 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A rectifying element, a warming heater, a smoothing capacitor connected in series to an AC power source, a control element connected to the smoothing capacitor, and a control circuit connected in parallel to the smoothing capacitor, The electric pot, wherein the control circuit turns on and off the control element according to the magnitude of the voltage across the smoothing capacitor. 2. A temperature sensor that detects the temperature of water in the electric pot and is connected to the control circuit is provided, and the control is performed in response to the temperature sensor detecting a water temperature that is lower than or higher than a heat retention temperature. The electric pot according to claim 1, wherein a circuit turns on and off the control element within a predetermined half wave, respectively.