JPS6314747Y2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) This invention relates to an electric water heater that automatically stops heating operation after heating water to boiling water, and is particularly configured to release steam generated during boiling to the outside. This relates to electric water heaters.

(Prior art) In general, this type of electric water heater is designed to stop the heating operation immediately after boiling, but in reality, the heating operation is stopped at the same time as the boiling starts. There is no such thing as boiling, and the boiling is stopped only after a certain amount of time has elapsed since the start of boiling. On the other hand, the amount of steam released to the outside is small at the beginning of boiling, and increases rapidly over time.

In such a situation, if a user is in the vicinity of the steam outlet without knowing that boiling has started, the user may suffer burns from the steam when the steam enters a state where it is violently ejected from the steam outlet. There was a risk of

(Purpose of this proposal) This proposal was made in view of this point.By installing a boil alarm that operates before the heater stops heating, it will notify you of boiling before a large amount of steam is spewed out, thereby ensuring safety. It was designed to be measured.

(Example) An example of the present invention shown in the drawings will be described in detail below.

First, in the electrical circuit diagram shown in Figure 1, 1 is an AC power supply, 2 is a main heater for heating and boiling, 3 is a heat retention heater, and 4 is ON when power is applied to the relay coil described later.
The relay switch 5 is a temperature fuse, and the main heater 2 is connected between both terminals of the AC power supply 1.
The parallel circuit between
and a relay switch 4 is connected in series to the main heater 2. Both the main and heat-retaining heaters 2 and 3 constitute heating means for heating the hot water in the container. Furthermore, the amount of heat generated by the heat retaining heater 3 is smaller than that of the main heater 2, and is set to balance the amount of heat radiated to the outside when the temperature of hot water is 90°C, for example, so that the temperature of hot water can be maintained at 90°C. .

6 is a DC smoothing circuit consisting of a low resistor 7, a diode 8 and a capacitor 9, which is connected between both terminals of the AC power supply 1 via a temperature fuse 5. 10 manually
A reboiling switch is turned on and off, 11 is a heat-sensitive element such as a negative characteristic thermistor that detects the boiling of water based on the steam temperature, and 12 is a boiling alarm such as a light emitting diode which, when turned on, indicates that boiling has started.

13 is a heating switching control circuit connected to the DC smoothing circuit 6 via a reboiling switch 10, which controls the heating means, particularly the main heater 2; In this control circuit 13, 14 is a switching element such as an SCR;
5 is a relay coil, 16 is a diode, 17 is a
Switching elements such as SCR, 18, 19, 20,
21 is a resistor, 22 is a capacitor, a parallel circuit of a relay coil 15 and a diode 16 is connected to the anode side of the switching element 14, and a resistor 18 is connected to the anode side of the switching element 17. A capacitor 22 is inserted between the anodes of the switching elements 14 and 17. Furthermore, the switching element 17 has a series circuit consisting of a resistor 18 and a negative characteristic thermistor 11 between the anode and the gate, and resistors 19 and 2 between the anode and the cathode.
0, a resistor 21 is inserted between the cathode and the gate, and the connection point between the resistors 19 and 20 is connected to the gate of the switching element 14. The light emitting diode 12 forms a series circuit with a resistor 23 and is connected in parallel to the resistor 21.
Note that the negative characteristic thermistor 11 activates the switching element 17 when sensing the steam temperature due to its relationship with the resistor 21.
Use a device with characteristics that allows it to turn ON and maintain the ON state even if the temperature drops.

Next, in FIG. 2, 24 is a container for storing hot water, 24' is an outer case that houses the container 24, and 2
Reference numeral 5 denotes an inner plug detachably fitted into the opening of the container 24, forming a steam passage 25'. 26 is the container 24
A lid body that opens and closes the opening of the steam passage 2 when it is closed.
A steam outlet 27 is formed which is continuous with 5', and a negative characteristic thermistor 11 is disposed in this outlet 27. 2
Reference numeral 8 denotes a band-shaped heating body wrapped around the lower outer periphery of the container 24, which is composed of a main heater 2 and a heat-retaining heater 3.
29 is a spout, and 30 is a handle. A temperature fuse 5 is disposed on the outer bottom surface of the container 24.

(Operation of Example) First, a case will be described in which hot water is once boiled and then kept at a predetermined temperature.

Now, when a predetermined amount of tap water is placed in the container 24 and the power is turned on, the negative characteristic thermistor 11 is in a high resistance state and the switching element 17 is turned off.
A gate current flows due to the resistance ratios 8, 19, and 20, and the switching element 14 is turned on, energizing the relay coil 15 and turning on the relay switch 4. Then, the hot water in the container 24 is heated by the main heater 2 and the heat retention heater 3, and the temperature gradually rises as shown by line A in FIG.
t After ₁ hour, it reaches the boiling point and starts boiling. When hot water starts boiling in this way, steam is generated and the steam begins to flow out from the steam outlet 27 of the lid body 26 through the steam passage 25' of the inner stopper 25, and this steam The resistance value of the negative temperature thermistor 11 that senses temperature decreases as shown by line B in FIG. 3, and the voltage at point D in FIG. 1 increases. Then, the resistance value of the negative characteristic thermistor 11 is
When the temperature drops to _R1 , the light emitting diode 12 lights up to notify that boiling has started. This type of notification is performed at the beginning of boiling, and since the amount of steam is still small at this time, it is possible to warn the user before the period shifts to the period when a large amount of steam is spouted out, and to encourage caution. Become.

When time t ₂ is reached, the voltage at point D rises to a value that turns on the switching element 17, turning the element 17 on. As a result, the gate current no longer flows through the switching element 14, and the switching element 14 is turned off, cutting off the current supply to the relay coil 15 and turning off the relay switch 4.

As a result, the heating means is switched from a heating and boiling state (position) caused by heating by the main heater 2 and the heat-retaining heater 3 to a heating-warming state (position) by heating only by the heat-retaining heater 3. At the beginning of this switching, the amount of heat radiated to the outside exceeds the amount of heat generated by the heat retention heater 3, so the temperature of the hot water gradually decreases, and when it eventually drops to about 90 degrees Celsius, the amount of heat radiated and the amount of generated heat are balanced.
From then on, the same temperature will be maintained. In this way, once the hot water in the container 23 is boiled, it can be kept at a predetermined temperature.

In addition, since no steam comes out from the steam outlet 27 in the heating and heat retention state, the temperature of the negative characteristic thermistor 11 decreases and the resistance value increases, but a gate holding current flows due to the relationship with the resistance value of the resistor 21, and the switching element 17 is maintained in the ON state, and accordingly, the switching element 14 and the relay switch 4 are also maintained in the OFF state.

In FIG. 3, line C is the negative characteristic thermistor 11.
This is a curve showing the relationship between temperature and time.

(Effects of the present invention) As described above, according to the structure of the present invention, by notifying the boiler before a large amount of steam is spouted out, it is possible to urge caution against steam and to ensure safety.

Furthermore, the present invention is not limited to the embodiments described above and shown in the drawings, but can of course be modified as appropriate within the scope of the invention, for example, a buzzer can be used as the boiling alarm, and the means for automatically stopping the heating operation after boiling and the means for operating the boiling alarm can be any means capable of achieving the intended purpose.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of the water heater of the present invention, FIG. 2 is a schematic explanatory diagram of the same configuration, and FIG. 3 is a diagram showing changes in hot water temperature and characteristics of the heat-sensitive element. 2: Main heater (for heating and boiling), 4: Relay switch, 11: Negative characteristic thermistor, 12: Light emitting diode (boiling alarm), 24: Container.

Claims (1)

[Scope of utility model registration request] a heating means for heating and boiling hot water in the container;
A steam venting passage that releases steam to the outside when hot water in the container boils; a temperature sensing element that detects the ambient temperature in the steam venting passage; and heating of the heating means by a change in the resistance value of the temperature sensing element. or in an electric water heater equipped with a control circuit for stopping the water heater,
An electric water heater characterized by being provided with a boil alarm that operates at an operating temperature lower than the operating temperature at which the heating means stops heating.