JPH0444712A - Operation control method for electric water heating appliance - Google Patents

Abstract

PURPOSE:To prevent the temperature of a heater from being increased even when no load-boiling operation is made on a very small amount of water and to improve completeness by deciding an abnormal state, e.g. a very small amount of water, no-load boiling at a time when a detecting temperature from a temperature sensor attains a value exceeding a given value and fby turning OFF a heater. CONSTITUTION:A control device 11 compares the temperatures of the upper and lower parts of a tank 2, inputted from an A/D converter 19, with each other at intervals of a specified time. When a temperature difference is below a given value, after temperature attains a preset value, ON and OFF of a heater 7 are controlled to perform normal heating operation. When the heater 7 is energized without controlling ON and OFF of the heater 7, in a case the speed of the increase of the upper part of the tank 2 is very lower than that of the bottom part of the tank 2, it is decided that an amount of water in the tank 2 is very low or empty. When a temperature difference DELTAt between the bottom part and the upper part of the tank 2 attains a given value, energization to the heater 7 is immediately stopped. Thus, the heater 7 can be prevented from overheating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the operation of a tabletop electric water heater.

[Conventional technology]

As shown in FIGS. 2 and 5, such an electric water heater has a tank (2
) and close the top opening of the tank (2) with the lid (3).
The lower part of the tank (2) is formed into a narrow diameter part, and a tank fixing plate ( 15) will be erected,
The upper part of this tank fixing plate (15) supports the upper part of the tank (2) from below.

A heater (7) is attached to the outer wall of the bottom of the tank (2), a heat insulating material (16) is placed around the narrow diameter part at the bottom of the tank (2), and a water injection pipe is connected to the bottom of the tank (2). (5) was led out of the exterior (1), and a water injection valve (12) having an operating lever (13) was connected to its tip.

The water inlet (12a) provided on the bottom of this water inlet valve (12)
) and the front of the exterior (1).
14), and one microphone for controlling the heater (7) etc. inside the front panel (10) within the protruding portion of the upper half of the exterior (1) to the front side.Control using a computer, etc. A device (11) is installed.

In the figure, (4) shows a cooler for cooling the water in the tank (2) when such a water heater is used as a water cooler.

In such water heaters, as a means for maintaining the temperature inside the tank (2) at a predetermined set temperature, the tank (2) has conventionally been used as a means for maintaining the temperature inside the tank (2) at a predetermined set temperature.
) A temperature controller using a thermostat (17) is provided on the bottom outer wall of the heater (17), and the output from the thermostat (17) is used to control the heater (7) on and off through the action of the control device (11).

In this way, the heater (7) is energized and the tank (2) is
The water in the tank (2) is heated and the water inlet (12) is opened by operating the control lever (13), and the hot water in the tank (2) is passed through the water inlet vibrator (5) and into the inlet (12a) of the water inlet valve (12).
) and used for drinks, etc.

[Problems to be solved by the invention] Temperature control using a thermostat installed at the bottom of the tank only detects the temperature at the bottom of the tank, and when the amount of water in the tank is extremely low or the tank is operated empty. , 4th
As shown in the figure, there is a time delay before the heat from the heater is transferred to the thermostat.

Therefore, when it is detected that the bottom temperature part of the thermostat has reached the set temperature and the power to the heater is cut off,
The heater has already reached a fairly high temperature, which not only risks deforming the tank, but also requires the use of an extremely expensive heater to protect it. Additionally, the tank and even the water heater itself may become hot, which may pose a danger to the surrounding area.

The purpose of the present invention is to provide an operation control for an electric water heater that can eliminate the disadvantages of the conventional example, prevent the heater from becoming high temperature even when running with a very small amount of water, and improve the integrity of the heater. The purpose is to provide methods.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an electric water heater in which a heater is provided at the bottom of a tank disposed inside the exterior, and a water injection valve is connected to the water injection pipe from the tank outside the exterior. A lower temperature sensor and a -L hot water temperature sensor are installed near the heater and on the outer wall of the upper part of the tank, and if the detected temperature from both temperature sensors is within a predetermined value, the control is activated. The gist of this system is to operate the heater by on/off control using device B, and when the water level reaches a predetermined value or higher, it is determined that there is an abnormal state such as extremely low water flow or dry operation, and the heater is turned off.

[Effect]

According to the present invention, the temperature at the bottom of the tank is detected by the bottom temperature sensor, and the temperature at the top of the tank is detected by the bottom temperature sensor, and if the difference between the temperatures detected by both temperature sensors is within a predetermined value, the temperature inside the tank is detected. Assuming that there is an appropriate amount of water, the control device turns on and off the heater and performs normal operation.

If the amount of water in the tank is extremely small or empty, the temperature rise at the top of the tank will be extremely slow compared to the rise in temperature at the bottom of the tank, so if the difference in temperature detected by the upper and lower temperature sensors exceeds a specified value. is considered to be an abnormal condition and the power to the heater is immediately stopped.

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a longitudinal sectional side view of an electric water heater in which the operation control method of the present invention is implemented, and FIG. 2 is a perspective view of the entire F. The same components as the conventional example shown in FIG. Reference signs are attached.

The overall configuration of the electric water heater is the same as that of the conventional example shown in FIG. ), the lower part of the tank (2) has a narrow diameter part, a heater (7) is attached to the outer wall of the bottom, and the heater (7) is attached to the projecting part of the upper half of the outer casing (1) to the front side. (7) etc. Control device (11) using a microcomputer etc.
) was installed.

In the water heater having such a configuration, the present invention further includes a tank (2) near the heater (7) on the bottom outer wall of the tank (2).
) A lower temperature sensor (8a) was provided to detect the temperature at the bottom, and an upper temperature sensor (8b) was provided at the upper part of the narrow diameter part of the tank (2) to detect the temperature at the upper part of the tank (2).

Figure 3 shows a block diagram of temperature control, and shows the control device (11
) is connected to the input side of the power supply circuit (20), an input device (21) such as a switch for changing set values such as temperature, and a sensor circuit for a lower temperature sensor (8a) and an upper temperature sensor (8b). (8c) is connected via an A/D converter (19), and a display device (22) such as a lamp, and a drive circuit (23) are connected to the output side of the control device (11).
) to connect the heater (7).

The control device (11) includes a lower temperature sensor =(
When the difference Δt between the temperatures detected by 8a) and the upper temperature sensor (8b) exceeds a predetermined value, the heater (7)
The temperature difference Δ is set so as to output an off signal to the drive circuit (23)
A predetermined value of t is set in advance.

Next, the effect will be explained.

During hot water operation, the drive circuit (23) is connected from the control device (11).
) and energizes the heater (7), which heats the water in the tank (2).

At this time, the lower temperature sensor (8a) detects the temperature at the bottom of the tank (2), the upper temperature sensor (8b) detects the temperature at the upper part of the tank (2), and the sensor circuit (8a) detects the temperature at the top of the tank (2).
C) is output to the A/D converter (19), where it is converted into a digital signal and output to the control device (11).

The control device (11) compares the lower and upper temperatures of the tank (2) input from the A/D converter (19) at regular intervals, and if this temperature difference Δt is less than a predetermined value, In other words, as shown in Figure 4, if the temperature rise at the bottom of tank (2) and the temperature at the top of the narrow diameter part of tank (2) are almost the same (A), there is a large amount of water in tank (2). After reaching the preset temperature, the heater (7) is controlled on and off to perform normal heating operation.

On the other hand, as shown in FIG. 4, when the heater (7) is energized without on/off control, the temperature (B) at the bottom of the tank (2) increases compared to the increase in the temperature (B) at the bottom of the tank (2).
If the temperature (C) at the top of tank (2) rises extremely slowly, it is determined that the amount of water in tank (2) is extremely small or empty, and the temperature at the bottom of tank (2) and the temperature at the top of tank (2) are adjusted. When the difference Δt reaches a predetermined value, the controller (11) outputs an off signal to the drive circuit (23) to immediately stop energizing the heater (7). This allows the heater (7) to be turned off at a low point before the temperature (D) of the heater (7) reaches a very high temperature.

[Effects of the Invention] As described above, the electric water heater operation control method of the present invention detects immediately at the initial stage of operation when heating operation is performed when the amount of water in the tank is extremely small or empty, and controls the operation of the heater.
1%t can be stopped, the heater can be prevented from rapidly rising to high temperature, the tank will not be deformed, and safety to the surroundings can be sufficiently ensured.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional side view showing an electric water heater in which the operation control method of the present invention is implemented, Fig. 2 is an overall perspective view of the same, Fig. 3 is a block diagram of the same control, and Fig. 4 shows the operation control operation. FIG. 5 is a longitudinal sectional side view showing a conventional example of a water heater. (1)...Exterior (2)...Tank (
3)... Lid (4)... Cooler (5
)...Water injection pipe (6)...Tank holding plate (
7)...Heater (8a)...Lower temperature sensor (8b)...Upper temperature sensor (8c)...Sensor circuit (lO)...Front panel (11)...Control device (12) )...Water inlet valve (12a)...Water inlet (13)...Operation lever (14)...Drain case (15)...
・Tank fixing plate (16)...insulation material (17)
... Thermostat (19) ... A/D converter (
20)...Power supply circuit (21)...Input device (
22)...Display device (23)...Drive circuit agent Patent attorney Masuo Daikun Figure 2 Figure 11 Figure 4 Figure FF Figure 5

Claims (1)

[Claims] In an electric water heater in which a heater is provided at the bottom of a tank disposed inside the exterior, and a water injection valve is connected to a water injection pipe from the tank outside the exterior, the heater is installed on the outer wall of the bottom of the tank and on the outer wall of the upper part of the tank, respectively. A lower temperature sensor and an upper temperature sensor are installed, and when the detected temperature from both temperature sensors is within a predetermined value, the control device operates by controlling the heater on and off, and when it reaches a predetermined value or more, the water flow is extremely low and the operation is performed dry. A method for controlling the operation of an electric water heater, which is characterized in that the heater is turned off when an abnormal state is determined.