JP2563526B2 - Electric water heater - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric water heater that heats and keeps a liquid contained in a container heated.

2. Description of the Related Art A conventional electric water heater of this type has a structure as shown in FIGS. 4 and 5, for example. That is, container 1
As shown in Fig. 5, "2" is displayed at the full water display position of the mounting frame 4 attached to the outer case 3 to mark the water level inside the container or to see the water level in the container. Was there.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described conventional configuration, it is difficult to understand whether or not the water is full, because it is indicated only by the marking 2, and the water in the container 1 is heated even if water is poured above the full water position. As a result, there is a risk that hot water will spill over from the discharge port due to thermal expansion of water during boiling.

The present invention solves such a problem. When the temperature inside the container is lower than the predetermined temperature, heating does not start when water enters the first detection position or higher, and when the temperature is higher than the predetermined temperature. An object of the present invention is to provide an electric water heater because it is possible to reliably detect an abnormality when water is added above the second detection position, stop heating of the heating element, and perform a notification to notify a danger. To do.

Means for Solving the Problems In order to solve the above problems, the electric water heater of the present invention,
A heating element that heats the liquid in the container, a control element that controls energization of the heating element, a water level tube that is connected to the container and indicates the water level in the container, and detects the temperature of the liquid in the container. A temperature detecting means, a first water level detecting means provided at a first detection position above the water level pipe, and a second water level detecting means provided at a second detection position above the first water level detecting means. If the temperature detected by the water level detection means, the notification means for making a notification by sound or light, and the temperature detection means is lower than a predetermined temperature only when the heating of the heating element is started, the first
The water level is detected by the water level detecting means, and at other times, the water level is detected by the second water level detecting means, and if the detected water level reaches the detection position of each water level detecting means, it is lower than the detection position. Until then, the control element is turned off, and the control means is operated.

Operation According to the above configuration, when heating is started, if the water level is higher than the first detection position (full water position), the first water level detection means detects and notifies the full water. Further, during heating, the second water level detecting means installed in consideration of thermal expansion of water detects full water, so that the amount of water is safe when detected by the first water level detecting means. Nonetheless, it is not judged that the water level rises due to the thermal expansion of water due to heating, and it is judged that the water level is higher than the thermal expansion amount of water due to the addition of water during heating. Will be detected. Further, when the reboil switch is pressed for heating while keeping the temperature warm, the second water level detecting means can detect full water, and when the temperature is lowered and automatic boiling occurs, water is added. Since it is possible to detect full water by the first water level detecting means, it is possible to reliably prevent malfunction, and at the time of boiling, which is a problem when heating with too much water as in the past. It is also possible to prevent the hot water from spilling out from the discharge port, and thus prevent problems such as burns and soiling of the table.

Example Hereinafter, one example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows the structure of the main part of an electric water heater according to an embodiment of the present invention. In FIG.
Is a container for containing the liquid, and the container 5 is provided on the side of the container 5.
A water level pipe 6 indicating the water level inside is connected. Reference numeral 7 denotes a first water level detecting means which is provided above the water level tube 6 and which is installed at a heating start position (referred to as a first detection position) which does not spill out from the discharge port during boiling due to thermal expansion of water, The first water level detecting means 7 is composed of a photodiode 7a and a phototransistor 7b. Reference numeral 8 is a second water level detecting means installed at a position above the first water level detecting means 7 that does not spill from the discharge port even during boiling (second detection position). The means 8 is composed of a photo diode 8a and a photo transistor 8b. Reference numeral 9 is a float which is in the water level tube 6 and which floats and sinks depending on the amount of liquid in the container 5. Reference numeral 10 is a heating element for heating the container 5 containing the liquid, and 11 is a control element for energizing the heating element 10. Reference numeral 12 is a notification means for notifying the outside that the position is above the detection position. 13 is a temperature detecting means for detecting the temperature in the container 5, 14 is a controlling means for driving the control element 11 and the notifying means 12, and the controlling means 14 outputs the first water level according to the output of the temperature detecting means 13. The phototransistors 7b and 8b of the detection means 7 and the second water level detection means 8 are turned on and off to determine whether or not the water level in the container 5 is at or above the detection position.

FIG. 2 shows a concrete route diagram of the electric water heater in one embodiment of the present invention. In FIG.
Is an AC power supply and 16 is a DC power supply. Reference numeral 17 denotes a microcomputer (hereinafter referred to as a microcomputer), which receives the outputs of the first water level detecting means 7, the second water level detecting means 8 and the temperature detecting means 13 as an input, and the control element 10,
The information is output to the notification means 11. In the first water level detection means 7 and the second water level detection means 8, when the floats 9 reach their detection positions, the floats 9 block the light from the photodiodes 7a, 8a, and the phototransistors 7 are detected.
Since b and 8b are turned off, "H" is input to the microcomputer 17. On the other hand, if the float 9 has not reached the respective detection positions, the phototransistors 7b and 8b receive the light of the photodiodes 7a and 8a and turn on, so that "L" is input to the microcomputer 17.

The control element 11 is a relay contact 11a, a relay coil 11b,
It is composed of a transistor 11c, and when "H" is output from the microcomputer 17 to the transistor 11c via the resistor 11d, a current flows through the relay coil 11b. As a result, the relay contact 11a is closed and the heating element 10 is energized.
Further, the notification means 12 is an LED 12a for displaying when the water is full and a buzzer 12
It is constituted by b and is driven by a command of the microcomputer 17 when full water is detected. The temperature detecting means 13
Is a thermistor 13d that connects resistors 13b and 13c that create a reference potential to the + side input terminal of the comparator 13a, and detects the temperature inside the container 5 at one side input terminal, and this thermistor 13d detects a temperature above a predetermined temperature. It is configured by connecting a resistor 13e having a value such that the output of the comparator 13a becomes "L" at this time.

FIG. 3 shows a flowchart of the main part of the microcomputer, and the operation will be described based on this flowchart. First, in step 1, the output of the temperature detection means 13 is input, and in step 2, it is determined whether or not the temperature information is equal to or higher than a predetermined temperature (here, 90 degrees),
If the temperature is equal to or higher than the predetermined temperature, the output of the second water level detection means 8 is input in step 3, and if the temperature is equal to or lower than the predetermined temperature,
Go to step 8. In step 8, it is judged whether or not the heating is started. If the heating is started, the output of the first water level detecting means 7 is input in step 9, and if the heating is in progress,
Go to step 3. Based on the results of these Steps 3 and 9, it is judged whether or not the water is full in Step 4. If the water is not full, in Step 10, if heating is in progress, the control element 11 is turned on, while while heating is in progress. If not,
The control element 11 is turned off and the process proceeds to step 7. On the other hand, if the water is full, the control element 11 is turned off even when the heating element 10 is energized as shown in step 5, the notification means 11 is turned on in step 5, and the process proceeds to the next step shown in step 6.

According to the present embodiment as described above, it is possible to easily prevent heating when there is a water level above the full water position.

EFFECTS OF THE INVENTION According to the present invention as is clear from the description of the above examples, if the water level exceeds the full water position when heating is started, heating is not started, and spills at the time of boiling during heating or heat retention. When water reaches a position where there is a risk, the control element that controls the energization of the heating element is turned off to stop heating, so it is possible to ensure that hot water spills from the discharge port due to thermal expansion of water. Further, at this time, since the notification means notifies the danger by the notification means, it is possible to provide a safer electric water heater.

[Brief description of drawings]

FIG. 1 is a block diagram showing the construction of the main part of an electric water heater showing an embodiment of the present invention, FIG. 2 is a specific circuit diagram of the electric water heater, and FIG. FIG. 4 is a flowchart showing a program, FIG. 4 is a partially cutaway perspective view of a conventional electric water heater, and FIG. 5 is an enlarged view of a portion A in FIG. 5 ... Container, 6 ... Water level tube, 7 ... First water level detecting means, 8 ... Second water level detecting means, 10 ... Heating element, 11 ...
Control element for heating element, 12 ... Informing means, 13 ... Temperature detecting means, 14 ... Control means, 17 ... Microcomputer.

Claims (1)

(57) [Claims] 1. A heating element for heating a liquid in a container, a control element for controlling energization of the heating element, a water level tube connected to the container for indicating a water level in the container, and a liquid in the container. A temperature detecting means for detecting the temperature of the water, and a first water level detecting means provided at a first detection position above the water level pipe,
A second water level detecting means provided at a second detection position above the first water level detecting means, an informing means for informing by sound or light, and the temperature only when heating of the heating element is started. If the temperature detected by the detecting means is lower than a predetermined temperature, the water level is detected by the first water level detecting means, otherwise the water level is detected by the second water level detecting means,
An electric water heater comprising: a control means for turning off the control element and operating the notification means until the detected water level reaches the detection position of each water level detection means until it becomes lower than the detection position.