JPS60227722A - Temperature controller of pot - 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 (a) Field of Industrial Application The present invention relates to a temperature control device for a water heater that heats and maintains the temperature of liquid in a container using a main heater and an auxiliary heater.

(b) Prior Art A conventional control device of this type is disclosed in Japanese Utility Model Publication No. 58-27708. In such devices, in order to set the temperature, in the case of a bimetal type thermostat, the distance between the bimetals must be changed, resulting in low accuracy.Also, only the auxiliary heater is energized when transitioning from the heating state to the keeping temperature state, so it is difficult to set the temperature of the container. Since the heat capacity of the heater is constant regardless of the amount of hot water inside, there is a drawback that the temperature cannot be maintained at a constant temperature. Furthermore, it has the disadvantage that if the amount of hot water in the container decreases, it will continue to boil.

(c) Purpose of the Invention In view of the above points, an object of the present invention is to maintain a substantially constant temperature regardless of the amount of liquid in a container and to prevent it from continuing to boil.

B) Structure of the Invention For this purpose, the present invention provides a thermistor for detecting the temperature of the liquid in the container, and a thermistor for detecting the temperature of the liquid in the container, in a water heater that heats and keeps the liquid in the container warm by a main heater and an auxiliary heater. The output is compared with a first set output that is variable by external operation, and a first set output having a first differential is
a second comparator that compares the detection output of the thermistor with a second set output that is variable by the external operation but does not exceed a predetermined value by a constant voltage means, and has a second differential; , a first control circuit that controls energization/de-energization of the main heater based on the comparison output of the first comparator; and a first control circuit that controls energization/de-energization of the auxiliary heater based on the comparison output of the second comparator. The second control circuit is configured to control the second control circuit.

(e) Examples An embodiment of the present invention will be described in detail below with reference to the drawings.

First, the structure of the water heater (1) will be described based on FIG. 1. (2) is a bottomed cylindrical exterior body with an open top.
The inner lid (3) has a top opening (4) on the top surface of the exterior body (2).
It is attached to occlude the An outer cover (5) is provided on the inner cover (3) so as to be openable and closable. (6) is a cylindrical container with a bottom, and a lower conduit (7) is vertically provided in the container (6), and the pressure at the upper end of the lower conduit (7) is determined by the pouring port (8).
An upper conduit (9) having a diameter is connected.

Then, when the operating body (10) is pressed, the pump mechanism aυ flows from the pouring port (8) through the conduit (71 (9)) to the container (
6) The liquid inside can be poured out.

α is 700W wrapped around the lower part of the outer periphery of the container (6).
(13I is a 50W auxiliary heater attached to the bottom of the container (6). (14) is a temperature adjustment device, and when the knob α9 is moved from side to side, the temperature inside the container (6) is The set temperature of the liquid can be changed. tm is a thermistor that detects the temperature of the liquid in the container (6), and aη is a power plug connected to a commercial power source.

Next, the control circuit will be explained based on FIG.

First, when the power plug surface is connected to a commercial power source, a DC constant voltage generating circuit generates DC power (VDD). R9 is a temperature detection circuit, and the thermistor (16) constituting this circuit has a characteristic that its resistance value decreases as the temperature rises, and is connected to a DC power source (VDD) via a resistor (R7). One end of the resistor (R2) is connected to ground, and the other end is connected to the thermistor (IIEI) and the resistor (R4).The connecting point is connected to the inverting input terminal of the first comparator end, and also to the inverting input terminal of the first comparator end. It is connected to the inverting input terminal of the comparator (21) of No. 2. Also, one end is connected to ground, and the resistor (R4) is a variable resistor ffR).
, are connected to a DC power supply (VDD) via a resistor (R8). Further, a variable resistor (VR) whose resistance value can be changed by the temperature control device I is connected to the non-inverting input terminal of the comparator end which constitutes the main heater control circuit (2 hot water) via (R3), and The comparator eυ that constitutes the auxiliary heater control circuit (c) via (c)
is connected to the non-inverting input terminal of

Further, the output terminal of the comparator (A) is connected to the transistor CI! via a resistor (R7). 4), and is connected to the DC power supply (VD) via resistors (R1) and (R8).
D). The emitter of the transistor is connected to the droplet power supply (VDD), the collector to the grounded diode (D,) and to the main heater control relay Q image.

On the other hand, the output terminal of the comparator Qυ is connected to the gate of the transistor (C) via a resistor (Ro), and is also connected to a DC power supply (VDD) via a resistor (RO) (RIJ). The emitter of the transistor (a) is connected to a DC power supply (VDD), the collector is connected to a diode ( ) and the auxiliary heater control relay @ which is connected to ground.

When the transistor (2) becomes conductive, the relay (c) is energized and its switch (25A) is closed, so that the main heaters a are energized. On the other hand, when the transistor (a) becomes conductive, the relay (5) is excited, its switch (27A) is closed, and the auxiliary heater (13) is energized.

The temperature at which the auxiliary heater (1, 1) stops energizing is lower than the temperature at which the main heater (I) stops energizing.
In order to determine the input potential of the comparator (to) and 121), the voltage applied to the resistor (L) is made larger than the voltage applied to the resistor (R6).

Further, the hysteresis of the first comparator (A) and the second comparator Qυ is determined by the feedback resistance (Rst), the resistance (R6), the feedback resistance (Rω), and the resistance (Ro), respectively.

Therefore, the hysteresis of the first comparator (a) is set to a temperature lower than the temperature at which the output of the second comparator C'l) changes from high level to low level.

Furthermore, the variable resistor (VR) can be operated externally, that is, by the temperature control device Q.
4) The resistance value of the knob a changes as the paddy moves, and the temperature can be set arbitrarily, so if the set temperature is set to a relatively high temperature, it will continue to boil, so this is partly to prevent this. is a Zuner diode as a constant voltage means connected to the DC power supply (VDD) (connection point 03 between the non-inverting input terminal of the second comparator υ and the resistor (Ro))
Connect to. That is, the input level to the non-inverting input terminal of the second comparator (2+) is prevented from rising above a predetermined voltage by the diode, and the temperature at which the auxiliary heater 0 stops being energized is, for example, 95° C. or lower. Can be set.

In this way, from the lowest temperature to the main heater steep collar energization start temperature, auxiliary heater 0 energization start temperature, auxiliary heater (1
The operation will be described below assuming that the energization termination temperature of the main heater (2) is set to be the energization termination temperature of the heater (31) and the energization termination temperature of the auxiliary heater (2) does not exceed 95°C.

First, it is assumed that the water heater (1) is sufficiently filled with water in the container (6) and the power plug is connected to the commercial power source.

At this time, when the temperature is set to 92°C by the temperature controller I,
The operating temperatures of both comparators (He1l) when the variable resistor (VR) shifts from the low level output state to the high level output state are 95°C and 93.5°C, respectively.
The following description will be made assuming that the operating temperature of the first comparator when it transitions from the I/REPEL output state to the low level output state is 89.5°C, and that of the second comparator Qυ is 91°C.

A DC power supply (VDD) is generated by a DC constant voltage generation circuit a8 using a commercial power supply. And as mentioned above, the container (6)
Since the temperature of the water inside is low, the thermistor ← e detects the low temperature and the resistance value is large and both comparators c! In both cases, the potential of the inverting input terminal is higher than that of the non-inverting input terminal, and a low level is output. Therefore, both transistors c24@ become conductive, the main heater control relay (c) and the auxiliary heater control relay (2) are energized, and their own switches (25A) (27A) are closed, so the main heater Q2 and the auxiliary heater 0 □□□ is energized, and the water in the container (6) is heated.

Eventually, when the water temperature in the container (6) rises and reaches 93.5℃, the second comparator (2υ) outputs a high level, the transistor 2 becomes non-conducting, and the auxiliary heater control relay (2υ is demagnetized). Then, the switch (27A) is opened and the auxiliary heater (1
3) is de-energized. However, the main heater 02 is energized and continues heating. When the temperature reaches 95°C, the first comparator (A) outputs a high level and similarly opens the switch (25A) to stop energizing the main heater (I).As a result, the water temperature gradually decreases. It turns out.

When the temperature of the hot water drops to 91° C., the resistance value of the thermistor (14) increases, and the potential at the inverting input terminal of the second comparator aυ becomes higher than the potential at the non-inverting input terminal.

Therefore, the comparator 121) outputs a low level, the transistor (A) becomes conductive, the relay (27) is energized, the switch (27A) is closed, and only the auxiliary heater a3 is energized. In this way, the temperature is controlled by energizing or de-energizing the auxiliary heater 0. Therefore, the temperature can be maintained at approximately 92°C. Of course, at this time, if the amount of hot water in the container (6) is small, the auxiliary heater (130) will be energized for a short time, and if it is large, the energization time will be longer. will not be consumed.

Then, when the amount of hot water decreases, the outer lid (5) and inner lid (3)
If you open it and refill water from the top opening (4),
As the water temperature decreases, it becomes heated and the thermistor (1
Since both comparators (21 (2υ) output low level by e, the main heater (1) and the auxiliary heater are energized, and are controlled again as described above.

Hereinafter, a case will be described in which the set temperature is set to 94° C. by operating the knob a9 of the temperature control device a4 in order to change the set temperature. In this case, the output of the second comparator Ca1) changes from high level to low level at 93°C, and conversely changes from low level to high level at 95.5°C. However, as mentioned above, the Zuner diode (c) is connected to the non-inverting input terminal of the second comparator Qυ, and the comparator eυ is held at a constant voltage, and the above-mentioned knob Q5
Despite one operation, the voltage is maintained at 5 so that it does not rise above a predetermined voltage. Therefore, it is possible to prevent the temperature from rising above 95°C.

(F) Effects of the Invention As described above, the present invention enables the main heater and the auxiliary heater to be controlled by a thermistor serving as a single temperature sensor, and the set temperatures of the main heater and the auxiliary heater can be set simultaneously with a single operation. It is easy to adjust the temperature. In addition, since the set voltage of the second comparator for controlling the auxiliary heater is prevented from exceeding a predetermined voltage, it is possible to control the temperature so that it does not rise above the predetermined temperature despite the temperature adjustment.
Since the water does not continue to boil, the amount of water does not decrease.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a water heater to which the control device of the present invention is applied, Fig. 2 is a front view of a temperature control device, and Fig. 3 is an electric circuit diagram showing one embodiment of the control device of the present invention. . (121...main heater, a3...auxiliary heater,
(16)...Thermistor, (A)...First comparator, (21)...Second comparator, Qa@...Transistor, (C)...Main heater control relay, Han... Auxiliary heater control relay, (R11) (R1's...
...Feedback resistor, (c)...Zuner diode. Applicant Sanyo Electric Co., Ltd. and 1 other agent Patent attorney Shizuo Sano 6 2nd rA-n

Claims (1)

[Claims] 1. Heat the liquid in the container using the main heater and auxiliary heater.
In the water heater for keeping warm, the thermistor detects the temperature of the liquid in the container, and the thermistor's detection output is compared with a first set output that is variable by external operation, and the first differential has a first differential. a second comparator that compares the detection output of the thermistor with a second set output that is variable by the external operation but does not exceed a predetermined value by a constant voltage means, and has a second differential; a first control circuit that controls energization/de-energization of the main heater based on the comparison output of the first comparator; and a first control circuit that controls energization/de-energization of the auxiliary heater based on the comparison output of the second comparator. A temperature control device for a water heater, comprising: a second control circuit for controlling the temperature of a water heater;