JPH0449918A - Water heater - Google Patents

Abstract

PURPOSE:To control a heater safely by providing a temperature uprise protecting means which turns OFF the heater compulsorily when a state in which temperature of hot water is higher than a set value continues longer than a prescribed time period. CONSTITUTION:A controller 16 consists of a warmth retaining control means 20 which turns OFF a heater when a temperature signal is higher, a boiling control means 21 which turns OFF the heater when a prescribed time elapses after input of boiling signal from a boiling detector 13, a priority control means 22 which puts warmth retaining control prior to boiling control, and a temperature uprise protection control means 23 which turns OFF compulsorily the heater when a state in which temperature signal is higher continues longer than a prescribed time period in a first temperature deciding means 18. In this constitution, if contact fusing due to aging of a boiling detector, bad transmission due to bad mounting of a boiling detector on an overflow pipe or the like occur, it can be detected without fail and a heater is turned OFF compulsorily. Accordingly, it never occurs that continuous power supply to a heater continues to heat the boiler though without water by vaporing out water in a boiler.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a water heating device used in a tea dispenser for dispensing 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. The hot water stored in the tank of this tea dispenser is controlled by a thermistor that detects the temperature of the water in the tank and controls the heater so that tea is always ready for drinking.
It is kept warm at -90C.

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 a heat 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 between. A hot water supply valve 5'' is provided. 6' is hot water pipe 4'
It is a hot water supply port installed at the tip of the 7' is a tea strainer located directly below the hot water supply spout for storing tea and sweets, and 8' is a tea cup. 9'
10' is a hopper for supplying new confectionery, and 10' is a confectionery exchange device which incorporates a geared motor 11'. 12
13' is a temperature sensor installed in the tank 2', and 13' has one end opened at the upper side of the tank 2' and the other end connected to the drain tank 14.
This is a boiling detector that is disposed in close contact with the outer wall of the overflow pipe 15'' that opens at 15'', and detects steam caused by boiling.

16' is a hot water temperature control that turns on the heater 3' when the temperature signal from the temperature sensor 12' is lower than the second set temperature, and turns off the heater 3' when it is higher; This control device performs boiling control by turning on the heater when the temperature is lower than the set temperature, inputting a boiling signal from the groove RA detector, and then turning off the heater, and also controls the entire tea dispenser 1'. 17' is a fan for exhaust heat and steam.

The operation of the conventional tea dispenser configured as described above will be explained. The temperature of the hot water in the tank 2' is kept at 85-90°C by detecting the temperature with a temperature sensor 12' and controlling the heater 3'. When the water temperature drops below the set temperature when the power is turned on or when water is supplied to the tank 2', boiling control is entered, the heater 3' is turned on at 70N, the water temperature rises, and the boil detector 18' detects steam heat due to boiling. When this is detected, the heater 8' is set to 0FFL/ and the boiling control is terminated. Then, when the user turns on the tea switch (not shown), the hot water supply valve 5' is activated, and the hot water in the tank 2' is poured into the tea strainer 7'' from the hot water supply port 6' and stored in the tea strainer 7'. Tea is supplied to the teacup 8' through the tea confectionery.

Problems to be Solved by the Invention However, with the above configuration, boiling a
#l If the detector malfunctions or the boiling detector is improperly installed, even though the boiling temperature is actually boiling during boiling control,
Since the boil detector does not give a boiling signal of 8, the heater cannot be controlled, and even when the water temperature reaches 100C, the heater does not turn off and continues to be energized, causing all the water to evaporate and resulting in dry cooking. there were.

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

Means for Solving the Problems In order to achieve this object, the water heating device of the present invention has temperature rise protection that forcibly turns off the heater if the water temperature remains higher than the set temperature for a predetermined period of time or more. It consists of means.

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

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

FIG. 1 is a block diagram of a water heater according to an embodiment of the present invention. In this embodiment, the water heater is used as 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 pipe, and a hot water supply valve 5 for controlling hot water supply is provided in the dark of the pipe. 6 is a hot water supply port provided at the tip of the hot water supply pipe 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. Reference numeral 13 designates a boiling detector which 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 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 that compares the temperature signal with a second reference temperature signal 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; If the temperature signal is higher, turn the heater on.
a heat retention control means 20 that performs heat retention control to turn off;
boiling control means 21 that performs boiling control that turns on the heater when the temperature signal is lower in the temperature determination means and turns off the heater after a predetermined time after inputting the boiling signal from the boiling a detector 13; a priority control means 22 that prioritizes boiling control over control; and the first temperature determination means 1
8, the temperature increase protection control means 23 forcibly turns off the heater when the state in which the temperature signal is higher continues for a predetermined period of time or more.

Next, the electric circuit shown in FIG. 2 will be explained. Reference numeral 624 is a power switch, in which the heater 3 and the temperature fuse 27 are connected in series through the normally open contact 26 of the first relay 25, and the temperature fuse 27 is connected in series through the power switch 28. The hot water supply valve 5 is connected, and the second
The geared motor 11 of the tea and snack exchanging device 10 is connected through the normally open contact 30 of the relay 29, and the 1* side of the power transformer 31 in the control device 16 is connected. A power supply circuit 32 is connected to the secondary side of the power transformer 31. The control device 16 has the temperature sensor 1 as an input.
2 and the boiling detector 13.

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 33 and an inverting input terminal of a comparator 34, respectively. A resistor R2 and a resistor R3 are connected to the non-inverting input terminal of the comparator 38, 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 is used to maintain the water temperature at 87-93C. Similarly, a resistor R4 and a resistor R5 are connected to the non-inverting input terminal of the comparator 34, and the resistor R4 The other end of the resistor R5 is connected to the DC power supply Vcc, and the other end of the resistor R5 is grounded to create a second reference voltage (second reference temperature signal) for boiling control. The reference voltage is lower than the first reference voltage, and the water temperature in tank 2 is 8.
It is set to be able to determine 0C°. The output terminal of the comparator 33 is connected to the input terminal a of the microcomputer 35, and the output terminal of the comparator 34 is connected to the input terminal A of the microcomputer 35. One end of the boiling m detector 18 is connected to a DC power supply Vcc,
The other end is grounded via a resistor R6 and connected to the input terminal C of the microcomputer 35. Output terminals d and e of the microcomputer 35 are connected to a buffer 36
and a first relay 25 having a normally open contact 26 via 87
and a second relay 29 having normally open contacts 30 .

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 tank 2 is at room temperature, the electrical resistance of the temperature sensor is R(25), and the potential at point A is V(
25). Therefore, in step 38, since the voltage at point A is lower than the second reference voltage V(80) for boiling control, the output of the comparator 34 becomes H, and H is input to the input terminal of the microcomputer 35. Here, since the potential at point A is lower than the first reference voltage V (90) for heat retention control, the output of the comparator 33 also becomes H, and H is also input to the input terminal a of the microcomputer 35; 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 39.

In step 89, H is output to the output terminal d, the first relay 25t-ONL and the normally open contact 26 are closed via the buffer 86, and the heater 3 is turned on.

The water in tank 2 is heated by heater 8 and its temperature rises to 1
When approaching 00C@, the voltage at point A becomes v(100) in step 40, and the first reference voltage for heat retention control V(9
3) Since it is higher, proceed to step 41. When the boiling occurs for more than ten minutes, steam is violently generated, and the boiling detector 13 installed on the outer wall of the overflow pipe 15 is turned off due to the heat of the steam, and in step 42, L is applied to the input terminal C of the microcomputer 35. is input. In step 43, three minutes after L is input to input terminal C, output terminal d
In step 44, the first relay 25 is turned OFF via the buffer 36, the normally open contact 26 is opened, and the heater 3 is turned OFF and the boiling control is ended. The generation of steam stops, the boiling detector 18 is turned on again, and the process returns from step 44 to step 38 again. At this time, the hot water in the tank 2 is approximately 1 ooc', the electrical resistance of the temperature sensor 12 is R (100), and the voltage at point A is V (100). Therefore, the voltage at point A is the second reference voltage V for boiling control.
(80), so proceed to step 45 and perform heat retention control.The water temperature in tank 2 will drop to 87℃ due to heat radiation.
Below, the electrical resistance of the temperature sensor 12 is R(87)
, and the potential at point A is the first reference voltage V (87)
, the output of the comparator 38 becomes H, and H is input to the input terminal a of the microcomputer 85. Then, in step 46, H is output to the output terminal d of the microcomputer 35, and the buffer 3
6, the first relay 25 is turned on to close the normally open contact 26, and the heater 3 is turned on.

When the temperature of the water in the tank 2 rises to 98C° or higher, the electrical resistance of the temperature sensor 12 becomes smaller than R(93),
In step 45, the potential at point A is set to the first reference voltage V (9
3) Since the output of the comparator 33 becomes L
become. The microcomputer-35 connects L to the output terminal d.
is output, and the first relay 25 is turned off via the buffer 86.
F to open the normally open contact 26, and in step 47, the heater 3 is turned to 0 FFL/, and the process returns to step 38.

When the user turns on the tea switch 28, 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 35 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.

Next, a case will be described in which the contacts of the boiling detector are welded due to deterioration over time, and heat transfer failure occurs due to improper attachment of the boiling detector to the overflow pipe. In this case, the boiling detector 18 does not output a boiling signal even though the water is sufficiently boiling, so the heater 3 is continuously energized. That is, in step 39 of the boiling control, H is output to the output terminal d, the first relay 25 is turned on via the buffer 36, the normally open contact 26t' 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 violently generated and the steam heat is transmitted to the boiling detector 13 provided on the outer wall of the overflow pipe 15. However, since the boiling detector 13 continues to be ON, the input terminal C of the microcomputer 35 remains at H level. At step 40, the voltage at point A is higher than the first reference voltage V (87), so at step 41, the 30-minute timer starts counting. When the input terminal C of the microcomputer 85 remains H for 80 minutes, temperature rise protection control is entered and the heater 3 is forcibly turned off in step 48.
do.

As described above, according to this embodiment, if the temperature signal from the temperature detector continues to be higher than the first reference temperature signal for 30 minutes or more during boiling control, the heater is forcibly turned off. A protective control means is provided, so if the contacts of the boiling detector are welded due to deterioration over time, or heat transfer is poor due to improper installation of the boiling detector to the overflow pipe, this will be reliably detected and the heater Forcibly turn off
do. Therefore, 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 temperature sensor for detecting the temperature of water in a tank, a boiling detector for detecting boiling, and a first reference temperature signal for comparing a temperature signal from the temperature sensor with a first reference temperature signal. a second temperature determination means that compares the temperature signal with a second reference temperature signal lower than the first reference temperature signal;
The first temperature determining means turns on the heater when the temperature signal is lower, and turns off the heater when the temperature signal is higher; and the second temperature determining means a boiling control means that performs boiling control that turns on the heater when the signal is lower and turns off the heater after a predetermined time after inputting the boiling signal from the boiling detector; and a boiling control means that gives priority to the boiling control over the previous heat retention control. By comprising a control means and a temperature rise protection control means that turns off the heater when the temperature signal in the first temperature determination means continues to be higher for a predetermined period of time or more, the contact point of the boiling detector due to aging deterioration can be prevented. If heat transfer failure occurs due to welding or improper attachment of the boiling detector to the overflow pipe, this will be reliably detected and the heater will be forcibly turned off, so all the hot water will evaporate by continuously energizing the heater. There is no possibility of dry cooking, 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. Priority control means, 23. Temperature rise protection means. Name of agent Patent attorney Shigetaka Awano and 1 other person Lit figure 2 - Tank 3 - Jinta 12 - Onjo Naji Tomb 13 - Takihato Achibutsu j --- M-ta! Figure 411115IIp HIIL lyrics

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 that performs heat retention control to turn off the heater when the temperature signal is lower than the second temperature determination means; boiling control means that performs boiling control to turn off the
priority control means for prioritizing boiling control over the heat retention control;
A water boiling device comprising temperature rise protection control means for turning off the heater when a state in which the temperature signal in the first temperature determination means is higher continues for a predetermined period of time or more.