JP7483209B2 - Electric water heater system - Google Patents

Description

This invention relates to an electric water heater system.

Conventionally, in a water faucet device using an electric hot water heater, if electricity is turned on to the heating unit when there is no water in the water tank, the so-called "dry-burning" state occurs, causing the temperature of the heating unit to rise, putting a strain on the system and possibly causing it to break down.

JP 2005-283024 A

In an electric water heater system that uses multiple electric water heaters as described above, when multiple electric water heaters do not contain water because the water supply valve was forgotten to be opened due to an event such as maintenance or handover, when the system administrator turns on the heating section of the electric water heater, dry-boil occurs for multiple electric water heaters, which places a burden on the system for multiple electric water heaters. In addition, to forcibly cut off the power to the heating section when dry-boil occurs, electric water heaters are equipped with software that stops the power supply when dry-boil is detected, a bimetal that physically cuts off the power supply, and a thermal fuse that melts due to the heat of dry-boil to cut off the power to the heating section. To use the electric water heater again, if the power is stopped by the software, the tank fill button must be pressed to fill the tank with water, if the bimetal is activated, the bimetal must be deactivated, and if the thermal fuse is activated, the thermal fuse must be replaced (hereinafter, pressing the tank fill button, deactivating the bimetal, and replacing the thermal fuse will be referred to as the dry-burn cancel operation.) If dry-burn occurs on multiple electric water heaters, the dry-burn cancel operation can place a heavy burden on the system administrator.

The present invention was made to solve the above problems, and aims to provide a practical electric water heater system that controls other electric water heaters to run in tandem with one electric water heater based on whether the other electric water heater runs dry, so that at least one electric water heater runs dry and the other many electric water heaters do not run dry, reducing the burden on the electric water heater system and reducing the burden on the system administrator due to the dry-burn cancellation operation.

To achieve the above object, the present invention provides a system that includes a plurality of electric water heaters and a server that manages the operation of the plurality of electric water heaters, each of which has a water storage tank for storing water, a heating unit for heating the water in the water storage tank, a detection unit for detecting whether the electric water heater is dry-burning, and dry-burning prevention means for stopping the flow of electricity to the heating unit when the detection unit detects dry-burning, and the server controls the other electric water heaters to work in conjunction with one of the electric water heaters based on the presence or absence of dry-burning detected by the detection unit of the electric water heater.

Conventional electric water heaters have the problem that if the water supply valve is forgotten to be opened, and there is no water in the water tank that stores water for multiple electric water heaters on a floor or in an entire building that shares the same water supply valve, when the system administrator turns on the electric water heater, all of the electric water heaters will run dry, placing a strain on the heating units, etc. of the electric water heaters. As a countermeasure to this, there are systems that stop the flow of electricity to the heating units as soon as they detect dry-burning using a dry-burn detection unit, which makes it possible to prevent fatal strain on the heating units, etc. This invention allows other electric water heaters to operate in conjunction with one another based on whether one electric water heater is dry-burning, in other words, by adjusting the operation of the heating section of the electric water heater that detected whether dry-burning is occurring to follow the operation of the heating section of the electric water heater that detected whether dry-burning is occurring. This allows at least one electric water heater to dry-burn, and not the other many electric water heaters, reducing the burden on the system caused by dry-burning, and reducing the burden on the system administrator because only one electric water heater needs to perform the dry-burn cancellation operation. This has a practical and excellent effect.

Preferably, the detection function has a transmission unit that transmits dry-burn detection information or a status signal used for dry-burn detection to the server, and a reception unit that receives an operation signal from the server, and the server controls the transmission unit to transmit an operation instruction signal to a group of a plurality of electric water heaters so that the group operates in accordance with the dry-burn result of at least one of the electric water heaters.

With this configuration, it is possible to coordinate the operation of the heating units of all electric water heaters in a group that shares a water supply main valve based on the result of dry-burning of at least one electric water heater. Conventionally, if dry-burning occurs in one electric water heater, all electric water heaters in the group, such as a building, floor, or booth, that shares the water supply main valve will dry-burn. However, this can be prevented in advance, and if no dry-burning is detected, it is suggested that the water supply main valve is open, so dry-burning caused by the water supply main valve will not occur, and many other electric water heaters can be safely started. As a result, many other electric water heaters will not dry-burn, reducing the burden on the system due to dry-burning, and since only one electric water heater needs to perform the dry-burn cancellation operation, the burden on the system administrator can also be reduced. In addition, it is possible to achieve the practically excellent effect of allowing electric water heaters to be used normally in groups where dry-burning is not occurring.

Preferably, the server controls the electric water heater to operate the heating unit or to instruct the administrator to operate the heating unit when it detects that at least one of the electric water heaters is not running dry.

This configuration consolidates the number of electric water heaters that would run dry if the main water valve was forgotten to be opened into one, and prevents dry-burning from occurring in many other electric water heaters. This reduces the burden on the system caused by dry-burning, and also reduces the burden on the system administrator because only one electric water heater is required to cancel dry-burning, providing an excellent practical effect.

Preferably, the server controls the electric water heater to stop the heating unit or to instruct the administrator to stop the heating unit when at least one of the electric water heaters detects dry-heating.

With this configuration, electric water heaters that would run dry due to forgetting to open the water supply valve can be consolidated into one, and many other electric water heaters do not run dry, reducing the burden on the system caused by dry-burning. In addition, since only one electric water heater needs to be operated to cancel dry-burning, the burden on the system administrator can be reduced. Furthermore, when all electric water heaters contain water and the heating sections of multiple electric water heaters are operated, compared to a method in which only one electric water heater is operated as a test to check whether the water supply valve is open, all electric water heaters are operated quickly from the time they are operated until they are ready to use, which provides an excellent practical effect of improving usability.

Preferably, the detection unit is characterized in that it determines that the heater is running dry if the amount of change per unit time in the temperature rise of the heater is equal to or greater than a predetermined value.

With this configuration, air has a smaller heat transfer coefficient than heat media such as water, so when the heater is in an empty-heating state, the amount of temperature rise during a specified period of time that the heater is heating is greater than when the heater is filled with heat media and the heat media is heated normally. Therefore, when the amount of change per unit time is equal to or greater than a specified value, it can be determined that the heater is in an empty-heating state.

Preferably, the dry-heat prevention means uses a bimetal made of two or more metal plates with different thermal expansion coefficients bonded together, and when the temperature of the heating section reaches a predetermined level or higher, the bimetal bends to cut off current to the heating section.

With this configuration, if the electric water heater runs dry and the heating unit fails to receive an instruction to stop operation for some reason, it is possible to reliably cut off power to the heating unit before the burden on the electric water heater increases.

Preferably, the dry-heat prevention means is characterized by using a temperature fuse that melts when the temperature of the heating section reaches or exceeds a predetermined temperature, cutting off the flow of electricity to the heating section.

With this configuration, if the electric water heater runs dry and the heating unit fails to receive an instruction to stop operation for some reason, it is possible to reliably cut off power to the heating unit before the burden on the electric water heater increases.

The present invention provides a control system for an electric water heater that reduces the burden on the system caused by dry-heating and also reduces the burden on the system administrator of canceling dry-heating.

1 is a sectional view of an electric water heater main body according to an embodiment of the present invention as viewed from above. 1 is a front view of an electric water heater according to an embodiment of the present invention; 1 is a cross-sectional front view of an electric water heater according to an embodiment of the present invention; FIG. 2 is a process diagram of an electric hot water heater system according to an embodiment of the present invention. 4 is a time chart showing the operation of each system in the electric hot water heater system according to the first embodiment of the present invention when dry-heating is not detected. 4 is a time chart showing the operation of each system when dry-heating is detected in the electric hot water heater system according to the first embodiment of the present invention. 6 is a time chart showing the operation of each system in the electric hot water heater system according to the second embodiment of the present invention when dry-heating is not detected. 10 is a time chart showing the operation of each system when dry-heating is detected in the electric hot water heater system according to the second embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
To facilitate understanding, the same components in each drawing are denoted by the same reference numerals whenever possible, and duplicate explanations are omitted.

As shown in Figures 1 to 3, an electric water heater 1 according to one embodiment of the present invention has a water storage tank 2 for storing water, and a heating unit 3 is provided inside the water storage tank 2, which can heat the water stored in the water storage tank 2. The electric water heater 1 also has a detection unit 4 that detects dry-burning, in which the heating unit 3 operates when there is no water in the water storage tank, and a tank water supply button 5 that supplies water to the water storage tank 2 after the detection unit 4 detects dry-burning.

The detection unit 4 is characterized by determining that the device is in dry-heating mode when the amount of change per unit time in the temperature rise of the heating unit 3 is equal to or greater than a predetermined value. Because air has a smaller thermal conductivity than heat media such as water, when the device is in dry-heating mode, the amount of temperature rise during a predetermined period of time during which heating is performed by the heating device is greater than when the heating device is filled with heat media and normally heats the heat media. Therefore, when the amount of temperature rise during a predetermined period of time is equal to or greater than a predetermined value, it can be determined that the device is in dry-heating mode.

Next, the start-up process of each system in the first embodiment will be described with reference to Figures 4 to 6. In the first embodiment, a large server such as that in a centralized control room is used. First, the power-on process of the electric water heater will be described. The purpose is to turn on the power of the electric water heater No. 1 10 to the electric water heater No. 3 34. It is assumed that the electric water heater No. 1 10 to the electric water heater No. 3 34 are in the same building, on the same floor, or in the same booth, and share the water supply valve 48. This makes it possible to coordinate the operation of the electric water heaters, such as the operation and stop of the heating parts of the electric water heater No. 1 10 to the electric water heater No. 3 34. This makes it possible to prevent dry-burning in the event that one electric water heater runs dry in all electric water heaters in a group such as a building, floor, or booth that shares the water supply valve. Furthermore, if no dry-burn is detected, this indicates that the water supply valve is open, so dry-burn caused by the water supply valve will not occur, and many other electric water heaters can be started safely. This prevents many other electric water heaters from dry-burning, reducing the burden on the system due to dry-burning, and also reducing the burden on the system administrator, as only one electric water heater needs to perform the dry-burn cancellation operation. Furthermore, electric water heaters can be used normally in groups where dry-burning is not occurring.

The administrator uses the administrator terminal 6 to send to the server 8 an instruction to power on the electric water heater No. 1 10 through electric water heater No. 3 34, which share the drainage pipe 46 and the water supply valve 48 that controls the water to the drainage pipe 46. The server 8 receives the power-on instruction and issues an instruction to power on the electric water heater No. 1 10 through electric water heater No. 3 34.

Next, the system start of electric water heater No. 1 10 will be explained. The purpose is to check whether the water supply valve 48 is open or closed. The server 8 transmits operation instructions for the heating unit 18 of electric water heater No. 1 10 to the receiving unit 12. If dry-boiling does not occur in the water storage tank 16 of electric water heater No. 1 10 for a specified period of time and water boiling is performed normally, the transmitting unit 14 transmits a message to the server 8 indicating that water boiling has been completed normally, and the server 8 determines that the water supply valve 48 is open.

When there is no water in the water storage tank 16 and dry-burning occurs, the transmitting unit 14 transmits a message indicating that dry-burning has occurred to the server 8, and the server 8 notifies the administrator terminal, while at the same time transmitting an instruction to stop operation of the heating unit to the receiving unit 12. The contents of the notification include the occurrence of dry-burning, an instruction to turn off the power to electric water heater No. 1 10, confirmation of the open/close status of the water supply valve 48, and an instruction to operate the tank water supply button 5. As shown in FIG. 6, when dry-burning occurs in electric water heater No. 1 10, not only does the heating unit 18 stop operation, but the system does not operate with only the power of electric water heater No. 2 22 and electric water heater No. 3 34 on.

In addition, in case the heating unit 18 does not receive the instruction to stop operation for some reason, a bimetal made of two or more types of metal plates with different thermal expansion coefficients bonded together is used to ensure that electricity to the heating unit 18 is cut off before the burden on the first electric water heater unit 10 increases, and when the temperature of the heating unit 18 reaches a predetermined temperature or higher, approximately 90 degrees or higher, the bimetal bends to cut off electricity to the heating unit 18. Alternatively, electricity to the heating unit 18 is cut off by using a temperature fuse that melts when the temperature of the heating unit 18 reaches a predetermined temperature or higher, for example 87 degrees or higher, to cut off electricity to the heating unit 18.

Next, the system start of the electric water heater No. 2 22 and the electric water heater No. 3 34 will be described. If the system start of the electric water heater No. 1 10 has determined that the water supply valve 48 is open, the server 8 transmits operation instructions for the heating unit 30 of the electric water heater No. 2 22 and the heating unit 42 of the electric water heater No. 3 34 to the receiving unit 24 and the receiving unit 36, and the heating unit 30 and the heating unit 42 start operating. Alternatively, an external terminal is notified that the heating unit 30 of the electric water heater No. 2 22 and the heating unit 42 of the electric water heater No. 3 34 are capable of heating. As shown in FIG. 5, it can be seen that the electric water heater No. 2 22 and the electric water heater No. 3 34 are linked together along with the electric water heater No. 1 10, triggered by the normal boiling of the electric water heater No. 1 10. Linking means, for example, that other electric water heaters follow suit and perform the same operation as one electric water heater.

Next, the operation monitoring of each system will be explained. In order to monitor the operation when there is an abnormality due to a water leak or a clogged pipe, dry-fire detection is performed following the previous process. This concludes the explanation of the start-up process of each system in the first embodiment.
By following these steps, at least one electric water heater No. 1 10 will be in dry-burn mode, and electric water heater No. 2 22 and electric water heater No. 3 34 will not be in dry-burn mode, and the time until dry-burn detection is shortened or eliminated, not only reducing the system burden on the heating section 30 of electric water heater No. 2 22 and the heating section 42 of electric water heater No. 3 34, but also significantly reducing the burden on the system administrator, as only one electric water heater 1 is required to perform the dry-burn cancellation operation.
For convenience of explanation, it is assumed that there are three electric water heaters 1, but there is no limit to the number of electric water heaters.

Next, the start-up of each system in the second embodiment will be described with reference to Figures 7 and 8. In the second embodiment, the server 8 does not monitor the operation of each electric water heater. The server 8 provided in the electric water heater No. 1 10 notifies the system administrator of the system information of each floor obtained by wired or shortwave communication. In addition, the server 8 has the role of, for example, sending an instruction to stop the operation of the heating unit 18 of the electric water heater No. 1 10 and stop the operation of the heating unit 30 of the electric water heater 2 when the electric water heater No. 3 detects dry-burning. Alternatively, the server 8 has the role of notifying an external terminal to stop heating the heating unit 18 of the electric water heater No. 1 10 and the heating unit 30 of the electric water heater No. 2 when the electric water heater No. 3 detects dry-burning. The system process will be described in detail below.

First, the power-on process for the electric water heater will be explained. The purpose is to power on electric water heater No. 1 10 through electric water heater No. 3 34. Using the administrator terminal, the system administrator sends an instruction to server 8 provided in electric water heater No. 1 10 to power on electric water heater No. 1 10 through electric water heater No. 3 34, which share a common drainage pipe 46 and a water supply valve 48 that controls the water to the drainage pipe 46. Server 8 powers on electric water heater No. 1 10, and then performs inter-system communication between electric water heater No. 1 10 through electric water heater No. 3 34, and issues a power-on instruction to electric water heater No. 2 22 and electric water heater No. 3 34.

Next, the system start of electric water heater No. 1 10 through electric water heater No. 3 34 will be explained. The server 8 provided in electric water heater No. 1 10 issues an instruction to start operation of the heating section 18 of electric water heater No. 1. After that, inter-system communication is performed between electric water heater No. 1 10 and the electric water heater through electric water heater No. 3 34, and an instruction to start operation is issued to the heating section 30 of electric water heater No. 2 22 and the heating section 42 of electric water heater No. 3 34. At this time, the instruction to start operation to each heating section is issued with an interval between them so that dry heating does not occur simultaneously in electric water heater No. 1 10 through electric water heater No. 3 34.

By following these steps, the number of electric water heaters that run on dry heat due to forgetting to open the main water supply valve can be limited to one, thereby reducing the burden on the system. Not only is it necessary to have only one electric water heater 1 perform the dry-heat cancellation operation, but the burden on the system administrator is also greatly reduced. Furthermore, compared to the first embodiment of the invention, all electric water heaters are quick to start up and ready for use by the user, making them easier to use.
For convenience of explanation, it is assumed that there are three electric water heaters 1, but there is no limit to the number of electric water heaters.

1 Electric water heater 2 Water tank 3 Heating unit 4 Detection unit 5 Tank water supply button
6 Administrator terminal 7 Bimetal 8 Server 9 Temperature fuse 10 Electric water heater No. 1 12 Receiving unit of electric water heater No. 1 13 Detection unit of electric water heater No. 1 14 Transmitter unit of electric water heater No. 1 15 Tank water supply button of electric water heater No. 1 16 Water storage tank of electric water heater No. 1 17 Stop valve of electric water heater No. 1 18 Heating unit of electric water heater No. 1 20 Water discharge device of electric water heater No. 1 22 Electric water heater No. 2 24 Receiving unit of electric water heater No. 2 25 Detection unit of electric water heater No. 2 26 Transmitter unit of electric water heater No. 2 27 Tank water supply button of electric water heater No. 2 28 Water storage tank of electric water heater No. 2 29 Stop valve of electric water heater No. 2 30 Heating unit of electric water heater No. 2 32 Water discharge device of electric water heater No. 2 34 Electric water heater No. 3 36 Receiving unit 37 of electric water heater No. 3 Detecting unit 38 of electric water heater No. 3 Transmitting unit 39 of electric water heater No. 3 Tank water supply button 40 of electric water heater No. 3 Water storage tank 41 of electric water heater No. 3 Stop valve 42 of electric water heater No. 3 Heating unit 44 of electric water heater No. 3 Water discharge device 46 of electric water heater No. 3 Drainage pipe 48 Water supply main valve

Claims (7)

A plurality of electric water heaters;
A server that manages the operation of the plurality of electric water heaters,
The electric water heater is
A water tank for storing water,
A heating unit that heats the water in the water storage tank;
A detection unit that detects whether the electric water heater is running dry;
and dry-heating prevention means for stopping the supply of electricity to the heating unit when the detection unit detects dry-heating of the electric water heater.
The electric water heater system is characterized in that the server controls the other electric water heaters to work in conjunction with one of the electric water heaters based on whether or not the one electric water heater is running dry, as detected by the detection unit of the one electric water heater. The detection function is
A transmission unit that transmits dry-burn detection information or a status signal used for dry-burn detection to the server;
A receiving unit that receives an operation signal from the server;
having
The electric water heater system according to claim 1, characterized in that the server controls the transmitting unit to transmit an operation instruction signal to a group of a plurality of the electric water heaters so as to perform operation corresponding to the result of dry-heating of at least one of the electric water heaters. When the server does not detect dry heating of one of the electric water heaters within a predetermined time,
The electric water heater system according to claim 1 or 2, characterized in that the heating section of the other electric water heater is controlled to start heating, or an external terminal is controlled to be notified that heating of the heating section is possible. When at least one of the electric water heaters detects dry-heating,
The electric water heater system according to claim 1 or 2, characterized in that the heating section of the other electric water heater is stopped from heating, or an external terminal is informed to stop heating the heating section. The electric hot water heater system according to any one of claims 1 to 4, characterized in that the detection unit determines that the heater is running dry if the amount of change in temperature rise per unit time of the heater is equal to or greater than a predetermined value. The electric hot water heater system according to any one of claims 1 to 4, characterized in that the dry-heating prevention means uses a bimetal made of two types of metal plates with different thermal expansion coefficients bonded together, and when the temperature of the heating section reaches a predetermined level or higher, the bimetal bends to cut off the flow of electricity to the heating section. The electric hot water heater system according to any one of claims 1 to 4, characterized in that the dry-heating prevention means uses a temperature fuse that melts when the temperature of the heating section reaches or exceeds a predetermined temperature, cutting off the flow of electricity to the heating section.

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