JPH0114770B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid warmer with sterilization and disinfection functions.

[Prior Art] Figure 3 is an electrical circuit diagram of a conventional liquid warmer disclosed in, for example, Japanese Patent Publication No. 57-805.
A series circuit of a temperature switch 2 for setting a heat retention temperature and a relay 10 having a contact 11 is connected in parallel with a series circuit of a heat retention heater 9 and a contact 11 of the relay 10. In addition, there is a temperature switch 3 that detects the water temperature below the heat retention temperature, and a self-holding contact 5 of the relay 6.
are connected in parallel, and a relay 6 and a temperature switch 4 for detecting boiling temperature are connected in series. When relay 6 is ON, water heater 8 is activated.
is connected to the power source 1, and has a contact point 7 that connects the heat-retaining heater 9 to the power source 1 when turned off.

In the above circuit configuration, for example, temperature switches 2, 3, and 4 are turned off at 85℃, 60℃, and 100℃ or higher, respectively.
For example, when the container is filled with water and connected to power supply 1, temperature switches 2, 3, and 4 detect the water temperature and are all turned on, and the relay is activated by the conduction of temperature switches 3 and 4. 6 is energized, the self-holding contact 5 is turned on and self-holding, while the contact 7 is connected between b and c, and the water boiling heater 8 is energized. Since this water heater 8 consumes a large amount of power, the water temperature rises rapidly and when it reaches 100°C (point A in Figure 4), the temperature switch 4 detects this and turns off.

At this time, temperature switches 2 and 3 are already in the OFF state, and the relay 6 is connected to the temperature switch 4.
It turns OFF at the same time as the OFF operation, contact 5 turns OFF and self-holding is released, and contact 7 connects a and c. In this way, room-temperature water is rapidly heated to a temperature of 100°C and boiled, achieving a sterilizing effect.

After relay 6 turns OFF, temperature switch 2 remains OFF for a while, so relay 10 also turns OFF.
It is OFF, and even if the contacts 7 of the relay 6 connect between a and c, the heat-retaining heater 9 is not energized and is allowed to cool naturally. When the water temperature drops to 85℃ (point B in Figure 4), temperature switch 2 is turned on.
-The OFF operation controls the relay 10 to intermittently energize the heat-retaining heater 9, increasing the temperature of the water in the container to 85℃.
to hold.

Here, when about half of the hot water kept in the container is taken out and new room temperature water is added to fill the container, the change in hot water temperature will be as shown in Figure 4. In other words, take out about half of the 85℃ hot water at point C in Figure 4 and boil it to about 10℃.
When filling the container with water, the temperature of the water in the container is D.
The temperature drops to about 40℃ at the point, but it turns on at 65℃ or below.
The temperature switch 3 detects this temperature and operates, activating the relay 6 and turning on the water heater 8.
is energized, heated again to 100℃ and brought to a boil.
After that, repeat the above-mentioned warming operation.

In this way, the same sterilization effect can be obtained even when room temperature water is newly added, or when the water temperature drops below the set heat retention temperature due to a power outage or the like.

[Problem that the invention seeks to solve]

Conventional liquid heat insulators are constructed as described above, and although they can achieve sterilization and disinfection effects through reboiling, they require multiple temperature switches, which increases the number of parts and makes them expensive. The problem was that the reliability of the circuit was low because it was mechanically controlled by opening and closing.

The present invention was made to solve the above-mentioned problems, and it is possible to reduce the number of parts and provide it at a low cost, as well as to eliminate the opening and closing part of the contact by electrical control, and to provide a highly reliable liquid warmer. The purpose is to obtain.

[Means for solving problems]

The liquid warmer according to the present invention includes a water boiling heater connected to a power source via a first semiconductor switch, a warming heater connected to the power source via a second semiconductor switch, and a water heater that responds to changes in water temperature. A temperature sensing element whose resistance value changes by changing the resistance value of the temperature sensing element, a change in the resistance value of this temperature sensing element is programmed in advance, and the first and second
a microcomputer for controlling a semiconductor switch; a first means for heating water with the water heater as the control means; a second means for detecting a resistance value and turning off the first semiconductor switch to de-energize the water heater, the water temperature falling from the boiling point;
A third means for detecting the resistance value of the temperature sensing element that reaches the heat retention temperature and turning on the second semiconductor switch to energize the heat retention heater to maintain the temperature of the hot water at the heat retention temperature; After maintaining the temperature at the heat retention temperature, if the water temperature drops below the heat retention temperature, the resistance value of the temperature sensing element corresponding to the temperature drop is detected and the first semiconductor switch is turned on. It has a fourth means for energizing the water heater to bring the temperature of the water to the boiling point again.

[Effect]

In the liquid heat insulator of the present invention, the first control means heats water with a water heater to raise the temperature of the water, and when the temperature reaches the boiling point, the second control means controls the resistance of the temperature sensing element that reaches the boiling point. After detecting the value, the first semiconductor switch is turned off, the water heater is de-energized, and when the water temperature drops from the boiling point, the third control means detects the resistance value of the temperature sensing element that reaches the warming temperature. Then, the second semiconductor switch is turned on and the heat-retaining heater is energized to maintain the water temperature at the heat-retaining temperature. When the water temperature drops below the heat-retaining temperature, the fourth control means adjusts the sensitivity according to the temperature drop. By detecting the resistance value of the temperature sensing element, the first semiconductor switch is turned on to energize the water heater and bring the water temperature back to the boiling point. Even if the water temperature drops below the set heat retention temperature due to additional input or power outage, it will reliably and automatically reheat to boiling temperature.

〔Example〕

An embodiment of the present invention will be described below. FIG. 1 shows an electric circuit of a liquid warmer according to an embodiment of the present invention. In the figure, 1 is a power source, 8 is a heater for boiling water, and 9 is a heater for keeping warm. 10 is a temperature sensing element attached to the outer bottom or outer surface of the container, and 11 is a control unit in which a control circuit consisting of a microcomputer, transistors, capacitors, diodes, resistors, etc. is incorporated. Reference numeral 12 denotes a first semiconductor switch for controlling a heater for boiling water, which is ON-OFF controlled by the control unit 11, and is, for example, a triac. Reference numeral 13 designates a semiconductor switch for controlling the heat-retaining heater 9, which is also ON-OFF controlled by the control unit 11, and is, for example, a triac. Reference numeral 14 denotes a dry-burning detection sensor for preventing an abnormal temperature rise of the water heater 8.

Here, the microcomputer incorporated in the control unit 11 calculates the resistance changes of the temperature sensing element 10 and the dry-burn detection sensor 14, and turns the triaxes 12 and 13 ON and OFF to control the water boiling heater 8 and the heat retention heater 8. Controls the power of the heater 9.

Next, the operation of the above configuration will be explained with reference to FIG. 2.

When water is poured into the container and the power supply 1 is connected, the control unit 11 calculates the resistance of the temperature sensing element 10 and makes the triax 12 conductive, thereby turning on the heater 8 for boiling water.
energize (point a in Figure 2). Thereafter, when the water temperature in the container rises and reaches point b in FIG. Then, heating by the water boiling heater 8 is stopped. When the temperature of the water in the container drops to point C in FIG. 2, a signal is output from the microcomputer, causing the triax 13 to conduct and current to flow through the heat-retaining heater 9, maintaining the set temperature.

Here, for example, when hot water is kept warm in a container and cold water at room temperature is newly poured into the container and the temperature of the water drops to point d in FIG. 2, the resistance of the temperature sensing element 10 changes. In response to a signal from the microcomputer, the triator 12 is turned on again, and the water heater 8 is energized to perform the same operation as described above to raise the water temperature to point e in FIG. 2.
Shifts to heat retention control.

In the circuit of the above embodiment, the dry-burn detection sensor 14 is provided separately from the temperature sensing element 10, but the temperature sensing element 10 may also be used.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, the change in resistance due to temperature of the temperature sensing element is controlled by a pre-programmed microcomputer, so cold water can be reliably added with just one temperature sensing element. Sterilization is carried out by re-boiling during power outages, and the number of parts can be reduced and the product can be provided at low cost. Further, since the control means is electrically switched without mechanically switching contacts, the reliability of the circuit is improved.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram of a liquid warmer showing an embodiment of the present invention, Fig. 2 is a temperature characteristic diagram of the same heat insulator, Fig. 3 is an electric circuit diagram showing a conventional example, and Fig. 4 is the same temperature. It is a characteristic diagram. In the figure, 8 is a heater for boiling water, 9 is a heater for keeping warm, 10 is a temperature sensing element, 11 is a control unit, 12
13 is a first semiconductor switch, and 13 is a second semiconductor switch.

Claims (1)

[Claims] 1. A water boiling heater connected to a power source via a first semiconductor switch, a heat-retaining heater connected to the power source via a second semiconductor switch, and a temperature sensor whose resistance value changes according to changes in water temperature. and a microcomputer for programming a change in the resistance value of the temperature sensing element in advance and controlling the first and second semiconductor switches according to the change in the resistance value of the temperature sensing element, the control means As a first means for heating water with the water heater, as the water is heated, the temperature of the water rises, and the resistance value of the temperature sensing element that reaches the boiling point is detected, and the first semiconductor switch is turned off. and a second means for de-energizing the water heater, and turning on the second semiconductor switch by detecting the resistance value of the thermosensor when the water temperature drops from the boiling point and reaches a heat retention temperature. , a third means for energizing the heat-retaining heater to maintain the hot water temperature at the heat-retaining temperature; after maintaining the water temperature at the heat-retaining temperature, if the water temperature drops below the heat-retaining temperature, the drop; The method further includes fourth means for detecting a resistance value of the temperature sensing element according to the temperature, turning on the first semiconductor switch, energizing the water boiling heater, and bringing the temperature of the water to the boiling point again. Features a liquid warmer.