JPS6311009B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heating control device for electric water heaters used in general households.

Conventional structure and its problems Conventionally, in this type of water heater, a heat-sensitive element such as a thermostat that senses the water temperature is operated at a temperature below the boiling point of water (for example, 93 degrees Celsius) to heat the water. Since the power supply to the heater that raises the temperature was stopped, the water could not be boiled and sufficient water sterilization and descaling effects could not be obtained.

In other words, since there are always variations in the operating temperature of the thermosensor, even if the operating temperature is set close to the boiling point of water, the thermosensor will not operate even though the water is boiling, resulting in continuous As some water heaters can cause a dangerous situation called boiling, as mentioned above, in current water heaters, the operating temperature of the heat-sensitive element must be set to operate when the water temperature reaches approximately 93°C. This avoided the above-mentioned danger.

Therefore, such water heaters have the disadvantage that they cannot sufficiently sterilize or descal water.

Therefore, as a method to eliminate these drawbacks, the first method is
There is a boiling type electric water heater as shown in the block diagram in the figure.

To explain its configuration, it includes a heat-sensitive element 1 that operates at a temperature below the boiling point of water, and a delay device 2 that stops energizing the heater 3 after a predetermined time has elapsed from the operation of this heat-sensitive element 1. , it becomes possible to stop energizing the heater 3 without fail after boiling the water.

However, in this boiling type water heater, once the power supply to the heater 3 is stopped, if you want to boil it again after a while, you do not have to add water to lower the temperature of the heat-sensitive element 1 to a predetermined temperature. Since the heater 3 is not energized, this method is complicated, and also has the disadvantage that additional power is consumed because the added water must also be heated.

Purpose of the Invention The present invention solves these conventional problems, and even after the water has boiled and the water heating has been completed and the power supply to the heater has been stopped, it is possible to continue the process by simply turning on the switch. An object of the present invention is to provide a heating control device for an electric water heater that can re-boil water by energizing the heater again for a predetermined period of time.

Composition of the Invention In order to achieve the above object, the heating control device for an electric water heater of the present invention provides a detection device that outputs a detection signal when the temperature of a temperature sensing element that detects the temperature of liquid (water) reaches a predetermined temperature. a charging/discharging device that starts charging based on a detection signal from the detection device; and an energizing device that stops energizing the heating element for heating the liquid when the charging/discharging device determines that a predetermined level has been reached. , a timer device for driving this energizing device for a predetermined period of time, an energizing switch for starting the operation of the timer device, and a stop switch for stopping the operation of the timer device. According to this configuration, once the liquid ( Even after the water (water) has boiled and has finished boiling, by turning on the energizing switch, the timer device can drive the energizing device for a predetermined period of time to energize the heating element, allowing the liquid to re-boil. Furthermore, by turning on the stop switch, the electricity supply to the heating element can be stopped immediately.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 2 and 3, reference numeral 11 denotes a temperature sensing element made of a thermistor having a negative temperature coefficient, and this temperature sensing element 11 is attached to the bottom of a container (not shown) containing liquid (water). ing. Reference numeral 12 denotes a detection device, and this detection device 12 is composed of resistors 19 to 21 and an open collector output type comparator 22 _.
A voltage _V It is input by dividing _Vcc .

13 is a charging/discharging device, and this charging/discharging device 13 is composed of a capacitor 23 for charging/discharging, a resistor 24 for charging, and a resistor 25 for charging/discharging.
The positive pole of the capacitor 23 and the other end of the charging/discharging resistor 25 are connected to _Vcc , and one terminal of the capacitor 23 and the other end of the charging/discharging resistor 25 are connected to one end of the charging resistor 24. The resulting output voltage _V1 of the charging/discharging device 13 is input to the - input terminal of a comparator 30 of the energizing device 14, which will be described next. Further, the other end of the charging resistor 24 is connected to the output of the comparator 22 of the detection device 12.

14 is an energizing device, and this energizing device 14 is connected to a resistor 2.
6 to 29, open collector output type comparator 3
0, PNP type transistor 31 and relay 32
As mentioned above, the output voltage V ₁ of the charging/discharging device 13 is input to the - input terminal of the comparator 30, while the + input terminal of the comparator 30 is determined by the resistors 26 and 27. A voltage V ₂ is given.
Also, one end of the resistor 28 is connected to _Vcc , and the other end is connected to the resistor 2.
9, and the other end of the resistor 29 is connected to the output of a comparator 30, and this connection point is designated as point A. In addition, the resistors 28 and 29
The connection point of is connected to the base of the transistor 31, and the emitter of this transistor 31 is connected to _Vcc ,
And the collector is connected to one end of the coil 32a of the relay 32, and the other end of the coil 32a is connected to GND.
It is connected to the. Also, the relay 32
The make contact 32b is connected in series with the heating element 15, and this series connection is connected to the AC power source 33.

17 is a timer device, and this timer device 17 is a low resistance 34 to 44, N gate thyristor (hereinafter referred to as
PUT) 45, 46, a charging/discharging capacitor 47, a PNP type transistor 48, an NPN type transistor 49, and an open collector output type comparator 50, and resistors 34 to 3.
The connection point (referred to as point B) of the resistors 34 and 35 of the series connection body of 6 is connected to the gate of PUT45, and the resistors 35 and 3
The connection points of 6 are connected to the bases of transistors 49, and the cathode of PUT 45 is connected to GND.
In addition, the anode of the PUT 45 is connected to the discharge resistor 37.
are connected to one end of each. The other end of the discharging resistor 37 is connected to the + pole of the capacitor 47 and one end of the charging resistor 38, and this connection point is referred to as point C. One pole of the capacitor 47 is connected to GND, and the other end of the resistor 38 is connected to the transistor 48.
The voltage V _B at the point B, the resistor 38, and the capacitor 48 set a predetermined timer time. In addition, the resistor 3
One end of 9 is connected to _Vcc , and the other end is connected to one end of resistor 40, and the connection point of these 39 and 40 is connected to the base of transistor 48, while the other end of resistor 40 is connected to one end of PUT 46. It is connected to GND via the gate and the energization switch 16.

The cathode of the PUT 46 is a transistor 49
The emitter of the same transistor 49 is connected to the collector of
Each is connected to GND. Also resistance 41
One end is connected to _Vcc , and the other end is connected to one end of resistor 42, the anode of PUT 46, and the + of comparator 50.
Connect to the input terminal (the voltage generated at this connection point is V ₃
), and the other end of the resistor 42 is connected to GND.
It is connected to the. The voltage V ₄ obtained by dividing V _cc by the resistors 43 and 44 is input to the - input terminal of the comparator 50, and this voltage V ₄ is higher than the voltage of V ₃ when the PUT 46 is OFF (non-conducting). is also set to a low value. The outputs of the comparators 50 are respectively connected to point A of the energizing device 14.

18 is a stop switch; this stop switch 18
is inserted between the base of the transistor 49 and GND, and by turning on this stop switch 18, the transistor 49 is turned off, and as a result, the
PUT 46 can be placed in an OFF (non-conducting) state.

Reference numerals 51 and 52 denote an auxiliary heating element and a temperature-sensitive reed switch, which is a heat-retaining circuit that keeps the liquid temperature at about 92 to 95°C after the liquid is heated by the heating element 15 and boils. The amount of heat generated by the heating element 15 is considerably smaller than that of the heating element 15. Furthermore, during heat retention, the temperature of the temperature sensing element 11 is set so as not to fall below Tr.

The operation of the above configuration will be explained with reference to FIGS. 3 and 4.

First, when water is placed in a container and the power supply 33 is turned on, the temperature of the water is initially low, so the resistance value of the temperature sensing element 11 is large, and therefore V _X > V _r , so the comparator 2
The output of the sensor 2 becomes "H", and the detection device 13 does nothing. Therefore, the comparator 30 of the energizing device 14
The input voltage of - input voltage V ₁ is greater than + input voltage V ₂
(= _Vcc ) becomes high, so the output of comparator 30=A
The potential at the point becomes O, and the transistor 31 turns on.
As a result, the relay 32 is turned on, the make contact 32b of the relay 32 is closed, the heating element 15 is energized, and the water is heated and heated.

The temperature of the temperature sensing element 11 also rises as the temperature of the water rises, and when it reaches a predetermined temperature Tr°C (at this time, the water temperature is T _W °C), V _X <V _r , so the output of the comparator 22 becomes "L" Therefore, the detection device 13 detects that a current flows from V _cc to the capacitor 23 and the resistors 24 and 25, the capacitor 23 is charged, and the output voltage V ₁ gradually increases with a time constant determined by the resistors 24 and 25 and the capacitor 23. and after the water boils,
When V ₁ becomes less than V ₂ , the output of comparator 30 becomes "H"
, transistor 31 turns off and relay 3
The make contact 32b of No. 2 is opened, and the power supply to the heating element 15 is stopped. After that, the temperature is maintained at 92 to 95° C. using the auxiliary heating element 51 and the temperature-sensitive reed switch 52.

Next, the operation of the timer device 17 will be explained. The timer device 17 remains active until the energization switch 16 is turned on.
is not doing anything, so the voltage at point C is V _C
is O, the PUT 45 is in the OFF state, and the PUT 46 is also in the OFF state with its gate potential being _Vcc , so V ₃ > V ₄ and the output of the comparator 50 is "H".
state, and the energizing device 14 is not driven.

When the energization switch 16 is turned on in such a state, the gate potential of the PUT 46 becomes O, the transistor 48 is turned on, and the PUT 46 and the transistor 49 are also turned on. When PUT 46 turns ON, V ₃ < V ₄ , so the output of comparator 50 =
The voltage at point A becomes O, and energization to the heating element 15 is started in the same manner as described above.

While the PUT 46 is on, its gate potential is O, so the transistor 48 is
The ON state is maintained, and current flows through the resistor 38 to the capacitor 47 to charge the V _C
gradually rises and after the water boils again, V _C becomes V _B
When the voltage exceeds PUT45, the gate voltage becomes O, so the transistor 49 turns off.
In order to cut off the anode current of PUT46, PUT46
and transistor 48 are turned off, resulting in V ₃
> _V4 , the output of the comparator 50 becomes "H" and the power supply to the heating element 15 is stopped.

That is, by simply turning on the energization switch 16, water that has been kept warm (92 to 95°C) can be brought to a boil again.

Next, to explain the special features of the timer device 17, the charge stored in the capacitor 47 is transferred to the resistor 37.
and discharges through PUT45, so PUT45
remains on for a while, but when the gradually decreasing discharge current becomes less than the holding current (trough current) value of the PUT 45, the PUT 45 turns off, and the timer device 17 returns to the state before the energization switch 16 was turned on.

On the other hand, turn on the power switch 16 and turn on the heating element 15.
When the stop switch 18 is turned on in the state of V _C < V _B while the water is being re-boiled by energizing, the transistor 49 is turned off, so it is easy to energize the heating element 15 in the same manner as described above. can be stopped.

Effects of the Invention As is clear from the above explanation, the heating control device for an electric water heater of the present invention is equipped with an energization switch and a timer device to enable energization of the heating element at will, so It is possible to easily re-boil even from a warm state, and since the timer device stops energizing the heating element after a predetermined period of time, there is no danger of continuous boiling, making it safe and energy-saving.

Further, since a stop switch is provided to stop the operation of the timer device, the power supply to the heating element can be stopped at will, and as a result, the device is very easy to use.

[Brief explanation of the drawing]

Fig. 1 is a system block diagram showing a conventional boiling type electric water heater, Fig. 2 is a system block diagram showing a heating control device for an electric water boiler according to an embodiment of the present invention, and Fig. 3 is a system block diagram showing a heating control device of an electric water heater according to an embodiment of the present invention. FIG. 4 is an electric circuit diagram of the heating control device showing one embodiment of the present invention, and FIG. 4 is a time chart showing the operation of the electric circuit diagram. 11... Temperature sensing element, 12... Detection device, 13...
...charging/discharging device, 14... energizing device, 15... heating element, 16... energizing switch, 17... stop switch, 18... timer device.

Claims (1)

[Claims] 1. A heating element that heats a liquid (water), a temperature sensing element that detects the temperature of the liquid, a detection device that outputs a detection signal when the temperature of the temperature sensing element reaches a predetermined temperature, and a detection device that outputs a detection signal when the temperature of the temperature sensing element reaches a predetermined temperature. A charging/discharging device that starts charging based on a detection signal, an energizing device that stops energizing the heating element when the charging/discharging device determines that a predetermined level has been reached, and a timer that drives the energizing device for a predetermined period of time. 1. A heating control device for an electric water heater, comprising: a power supply switch for starting the timer device; and a stop switch for stopping the timer device.