JPH03231618A - Water boiling apparatus - Google Patents

Abstract

PURPOSE:To prevent the title apparatus from being heated without water at the time when an electric current is continuously applied to a heater because of a thermal detector trouble or the like by providing a temperature rise- protecting means whereby the heater is forcibly turned off when a boiling signal from a boiling detector is continued beyond a definite time. CONSTITUTION:A thermal detector 12 is fixed in a hot water tank 2, and a boiling detector 13 is closely fixed on the outer wall of an overflow pipe 15, of which the one end is open at the upper part of the side face of the tank 2 and the other end is open at a drain tank 14. A control device 16 has a temperature-retaining control means 20 whereby a thermal signal from the thermal detector 12 is compared with a first criterion for the thermal signal and when the thermal signal is higher than the criterion, a heater is turned off, and a boiling control means 21 whereby when a boiling signal is inputted from a boiling detector 13, the heater is turned off in a time of A, and a temperature rise-protecting control means 22 whereby when the boiling signal is continued for a time of B longer than the time of A, the heater is turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a water heating device used in a tea dispenser that supplies tea.

2. Description of the Related Art In recent years, tea dispensers that store hot water in a tank and supply a predetermined amount of hot water to sweets to brew tea have become widely used in offices, restaurants, and the like. For example, this is
It is shown in Publication No. 90.

The hot water stored in the tank of this tea dispenser is kept at a temperature of 85 to 90C by detecting the temperature of the water in the tank with a thermistor and controlling the heater so that tea is always ready for drinking.

A conventional tea dispenser will be described below with reference to FIG.

1' is a tea dispenser, 2'' is a hot water tank covered with an insulating material such as glass wool, and a heater 3' is installed on the bottom. 4' is a hot water supply vibrator, which controls hot water supply in the dark. A hot water supply valve 5' is provided. 6" is a hot water supply pipe 4.
It is a hot water supply port installed at the tip of . 7' is a tea strainer located directly below the hot water supply spout for storing tea and sweets, and 8' is a teacup. 9′
10' is a hopper for supplying new confectionery, and 10' is a confectionery exchange device which incorporates a geared motor 11'. 12'
is a temperature sensor installed in the tank 2'. 18' is a control device 14 that controls the temperature of the hot water based on the signal from the temperature sensor 12' and also controls the entire tea dispenser 1';
′ is a fan for exhaust heat and steam.

The operation of the conventional tea dispenser configured as described above will be explained. The hot water in the tank 2' is kept at a temperature of 85 to 90°C by detecting the temperature with a temperature sensor 12'' and controlling a heater 3''. When the user turns on the tea switch (not shown), the hot water supply valve 5' operates and the hot water in the tank 2' is poured into the tea strainer 7' from the hot water supply port 6', and the tea confectionery stored in the tea strainer 7' is poured. Through it, tea is supplied to teacup 8''.

Problems to be Solved by the Invention However, with the above configuration, if the temperature sensor malfunctions due to aging or there is a poor connection in the electrical wiring connecting the temperature sensor and the control device, the heater cannot be controlled. , the heater will turn off even if the water temperature exceeds 90°C.
The problem was that the electricity would be turned on continuously, causing all the hot water to evaporate and resulting in dry cooking.

In view of the above problems, the present invention provides safe control of a heater.

Means for Solving the Problems To achieve this object, the water heating device of the present invention comprises a temperature rise protection means that forcibly turns off the heater when a boiling signal from a boiling detector continues for a predetermined period of time or more.

Effect: With this configuration, if the heater is continuously energized due to a malfunction of the temperature sensor or the like, the heater is forcibly turned off after a predetermined period of time to prevent dry cooking.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a water heating device in an embodiment of the present invention. This example shows a case where the device is used in a tea dispenser. 1 is a tea dispenser, 2 is a hot water tank covered with a heat insulating material such as glass wool, and a heater 3 is provided on the bottom surface. 4 is a hot water supply vibrator, between which a hot water supply valve 5 for controlling hot water supply is provided. 6 is a hot water supply port provided at the tip of the hot water supply vibrator 4. 7 is a tea strainer located directly below the hot water supply spout for storing tea and sweets, and 8 is a teacup. Reference numeral 9 denotes a hopper for supplying new confectionery, and 10 denotes a confectionery exchange device, which incorporates a geared motor 11. 12 is a temperature sensor provided in the hot water tank 2. A boil detector 13 is disposed in close contact with the outer wall of an overflow pipe 15 which has one end opened at the upper side of the tank 2 and the other end opened into the drain tank 14, and detects steam caused by boiling. 16 is a control device that controls the entire tea dispenser, and 17 is a fan for exhaust heat and steam.

The control device 16 includes a first temperature determination means 18 that compares the temperature signal from the temperature sensor 12 with a first reference temperature signal;
A second temperature determination means 19 compares the temperature signal with a second reference temperature signal lower than the first love temperature signal, and when the temperature signal is lower in the first temperature determination means, the heater is turned on and the temperature signal is Turns off the heater when the
and boiling control means that turns on the heater when the temperature signal is lower in the second temperature determination means and turns off the heater after A time after inputting the boiling signal from the boiling detector 13. 21, and a temperature rise protection control means 22 which turns off the heater when the boiling signal from the boiling detector continues for 8 hours, which is longer than time A.

Next, the electric circuit shown in FIG. 2 will be explained.

23 is a power switch, the heater 8 and the temperature fuse 26 are connected in series via the normally open contact 25 of the first relay 24, the hot water supply valve 5 is connected via the tea switch 27, and the second relay 28 is normally open. The gear motor 11 of the tea and snack exchanging device 10 is connected via the contact point 29, and the control device 16
The primary side of the power transformer 30 inside is connected. A lightning source 31 is connected to '2*m of the power transformer 30. The control device 16 has the temperature detector 12 and the boiling detector 13 as inputs.

The temperature sensor 12 is an NTC thermistor, and has a negative temperature characteristic in which the electrical resistance decreases as the temperature of the object to be detected increases and the electrical resistance increases as the temperature decreases.

One end of the temperature sensor 12 is connected to a DC power supply Vcc, and the other end is grounded via a resistor R1. A connection point A between the temperature sensor 12 and the resistor R1 is branched into two branches, and is connected to an inverting input terminal of a comparator 32 and an inverting input terminal of a comparator 33, respectively. A resistor R2 and a resistor R3 are connected to the non-inverting input terminal of the comparator 32, the other end of the resistor R2 is connected to the DC power supply Vcc, and the other end of the resistor R3 is grounded. First reference voltage for control (first reference temperature signal)
is making. The first reference voltage has hysteresis and maintains the water temperature at 87-93°C. Similarly, a resistor R4 and a resistor R5 are connected to the non-inverting input terminal of the comparator 33, the other end of the resistor R4 is connected to the DC power supply Vcc, and the other end of the resistor R5 is grounded. , generates a second reference voltage (second reference temperature signal) for boiling control. Note that the second reference voltage is lower than the first reference voltage, and is set so that it can be determined that the water temperature in the tank 2 is 80°C. The output terminal of the comparator 32 is connected to the input terminal a of the microcomputer 34, and the output terminal of the comparator 33 is connected to the input terminal a of the microcomputer 84.

One end of the boiling detector 13 is connected to the DC power supply Vcc, and the other end is grounded via a resistor R6 and connected to the input terminal C of the microcomputer 34. Output terminals d and e of the microcomputer 34 are connected to the buffer 3.
A first relay 2 with normally open contacts 25 via 5 and 36
4 and a second relay 28 having normally open contacts 29 .

The water heating device configured as described above will be explained using the flowchart of FIG. 3 and the timing chart of FIG. 4.

First, when the power is turned on, the water in the tank 2 is at room temperature, the electrical resistance of the temperature detector is 25Ω, and the potential at point A is 25V. Therefore, in step 37, since the potential at point A is lower than the second reference voltage 80V for boiling control, the comparator 3
3 becomes H, and H is input to the input terminal of the microcomputer 34. Here, since the potential at point A is lower than the first reference voltage 90V for heat retention control, the comparator 32
The output of the microcomputer 34 also becomes H, and H is also input to the input terminal a of the microcomputer 34.
Since boiling control is given priority over heat retention control according to the preset program, boiling control is entered and the process proceeds to step 38. In step 38, H is output to the output terminal d,
The first relay 24 is turned on via the buffer 35, the normally open contact 25 is closed, and the heater 3'#: is turned on. tank 2
The water inside is heated by the heater 3 and its temperature rises. When boiling occurs, steam is generated violently, and the boiling detector 13 installed on the outer wall of the overflow pipe 15 is 0F due to the heat of the steam.
F, and in step 39 the microcomputer 34
L is input to input terminal C of.

In step 40, L is input to input terminal C and 3
After a minute, L is output to the output terminal d, and in step 41, the first relay 24 is turned OFF via the buffer 35, the normally open contact 25 is opened, and the heater 3 is turned OFF to end the FFL/boiling control. The generation of steam stops, the boiling detector 13 is turned on again, and the process returns from step 41 to step 37 again. At this time, the hot water in the tank 2 is approximately 100C', the electrical resistance of the temperature sensor 12 is 100Ω, and the potential at point A is 1
It is 00V. Therefore, since the potential at point A is higher than the second reference voltage 80V for boiling control, the process proceeds to step 43 and heat retention control is performed. The temperature of the water in tank 2 decreased due to heat radiation, causing 87.
When the temperature is below C°, the electrical resistance of the temperature sensor 12 is 87Ω.
, and the potential at point A becomes lower than the first reference voltage 87V, so the output of the comparator 32 becomes H,
H is input to input terminal a of the microcomputer 34. Then, in step 44, H is output to the output terminal d of the microcomputer 34, the first relay 24 is turned on via the buffer 35, the normally open contact 25 is closed, and the heater 3 is turned on. Since the water temperature has not reached boiling and the boiling detector 13 is ON, the input terminal C of the microcomputer 34 is H, and the process returns from step 45 to step 43. When the temperature of the water in the tank 2 further increases to 93C or higher, the electrical resistance of the temperature sensor 12 increases to 93C.
Ω, and in step 43, the potential at point A becomes higher than the first reference voltage of 93V, so the 8-power of the comparator 32 becomes L. The microcomputer 34 outputs L to the output terminal d, turns the first relay 24 to 0FFL/ through the buffer 35 to open the normally open contact 25, and at step 46 turns the heater 3 to 0FFL/ to return to step 37.

When the user turns on the tea switch 27, the hot water supply valve 5 operates, and the hot water in the hot water tank 2 is poured from the hot water supply port 6 into the tea strainer 7, passes through the tea confectionery stored in the tea strainer 7, and makes tea. is poured into a container such as a teacup. Here, since the tea confectionery in the tea strainer 7 becomes waste when an appropriate amount of tea is supplied, the microcomputer 34 is programmed in advance so that the confectionery is automatically supplied from the hopper 9 after a certain amount of tea is supplied. It is something that exists.

If the temperature sensor becomes disconnected or malfunctions due to age-related deterioration, or if the electrical wiring connecting the temperature sensor and the control device becomes disconnected or has a poor connection, the electrical resistance of the temperature sensor will increase significantly. Therefore, the potential at point A becomes close to 0■ and lower than the first reference voltage 80V and the second reference voltage 87V.

Therefore, the process proceeds from step 43, which is the normal heat-retaining state, to step 44, and the heater 8 continues to be turned on. Eventually, the boiling occurs and the boiling detector 18 is turned off due to the heat of the steam, and in step 45 L is input to the input terminal C of the microcomputer 34. The voltage at point A is O■, the heater 3 continues to be turned on, boiling continues, and L is input to input terminal C to control the boiling. However, after a predetermined time (30 minutes), the heater 8 is forcibly turned off.

As described above, according to this embodiment, by providing a temperature rise protection control means that turns off the heater when the boiling signal from the boiling detector continues for a predetermined period of time, it is possible to prevent disconnection and failure of the temperature detector due to aging deterioration, If a disconnection or poor connection occurs in the electrical wiring connecting the detector and the control device, this will be reliably detected and the heater will be forcibly turned off.
Continuous energization of the heater will not cause all of the hot water to evaporate and result in dry cooking. In addition, by controlling boiling, it is possible to reliably remove chlorine from tap water and provide odor-free hot water that is perfect for tea, and can also be used as a boiling detector for boiling control and temperature rise protection control. By doing so, costs can also be rationalized. .

Effects of the Invention As described above, the present invention includes a tank for storing hot water, a heater provided in the tank, a temperature detector for detecting the temperature of the water in the tank, a boiling detector for detecting boiling, and a temperature sensor for detecting boiling water. a first temperature determination means for comparing a temperature signal from the detector with a first reference temperature signal; a second temperature determination means for comparing the temperature signal with a second reference temperature signal lower than the first reference temperature signal; a heat retention control means that turns on the heater when the temperature signal is lower in the first temperature determination means and turns off the heater when the temperature signal is higher; Heater 70N
and boiling control means that turns off the heater after A time after inputting the boiling signal from the boiling detector, and temperature rise protection that turns off the heater when the boiling signal from the boiling detector continues for 8 hours longer than A time. By providing a temperature rise protection control means that turns off the heater when the boiling signal from the boiling detector continues for a predetermined period of time, the temperature detector can be prevented from disconnecting or malfunctioning due to aging deterioration. If there is a disconnection or poor connection in the electrical wiring connecting the controller and the control device, this will be reliably detected and the heater will be forcibly turned off. It is something that will never happen, and its practical effects are great.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a water heating device according to an embodiment of the present invention;
3 is a flowchart showing the operation of the device, FIG. 4 is a timing chart showing the operation of the device, and FIG. 5 is a configuration diagram of a conventional water boiling device. 2. Tank, 3. Heater 12. Temperature detector,
13... Boiling detector, 18... First temperature determination means, 19
・Second temperature determination means, 20・Heat retention control means, 21.
Boiling control means, 22. Temperature rise protection means.

Claims (1)

[Claims] a tank for storing hot water; a heater provided in the tank;
a temperature detector for detecting the temperature of water in the tank; a boiling detector for detecting boiling; a first temperature determination means for comparing a temperature signal from the temperature sensor with a first reference temperature signal; a second temperature determination means that compares a second reference temperature signal that is lower than the first reference temperature signal; and a heater is turned on when the temperature signal is lower in the first temperature determination means; and when the temperature signal is higher, the heater is turned on; a heat retention control means for turning off the heater when the second temperature determination means turns on the heater when the temperature signal is lower than the second temperature determination means, and turning off the heater after A time after inputting the boiling signal from the boiling detector;
and a temperature rise protection control means that turns off the heater when a boiling signal from a boil detector continues for time B, which is longer than time A.