JPH07180912A - Electric warm water apparatus - Google Patents

Abstract

PURPOSE:To provide an electric warm water apparatus in which, even if a circuit system of a microcomputer of a controller has run into trouble, its remedy is easy and an operation can be effectively started and a structure for backing-up it is simple and inexpensive. CONSTITUTION:The electric warm water machine comprises a switch 4 for cutting OFF a connection of a microcomputer 3a to a small-sized relay 21 and a temperature operated switch 5 which can be connected to an operating circuit 30 of the relay 21. The switch 5 is disposed at a position where a temperature of a hot water storage tank 1 can be sensed and so formed as to connect or cut OFF an operating power source 23 of the relay 21 in response to temperature changes of the tank.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water storage type electric water heater provided in a general house or the like.

[0002]

2. Description of the Related Art As an electric water heater installed in a general house, a hot water storage tank having a water supply port at the bottom and a hot water outlet at the top, and an electric heater attached to the bottom of the tank are provided. Generally, the structure is such that the water stored in the hot water storage tank is heated by a heater, and the convection of the water caused by this heating raises the entire water in the tank to the boiling temperature. And the above-mentioned boiling operation is usually configured to be performed in the midnight power energization time zone (11:00 pm to 7:00 am).

Further, in such an electric water heater using late-night electric power, peak shift calculation is performed using the feed water temperature of the hot water storage tank and the like based on the calculation result in order to smooth the electric power load. An energization control system is adopted in which the start of energization is shifted to the start of the energization time of midnight power (11:00 pm). Further, a control device incorporating a microcomputer is conventionally used for controlling the energization of this kind of electric water heater.

[0004]

According to the energization control type electric water heater described above, when the circuit system of the microcomputer of the control device fails, the boiling operation cannot be performed unless the circuit system is repaired. Becomes Therefore, it is necessary to take measures when the microcomputer fails.

As a countermeasure against the failure, conventionally, when a failure occurs, an operation circuit system of a small relay operated by a control signal of a microcomputer is disconnected by a switch operation, and a power relay on a main power supply circuit side is directly operated. A technique has been proposed (JP-A-2-106655). However, in the circuit configuration described in this publication, since the power relay is for direct current, a diode is required in the main power supply circuit system, and an expensive three-pole changeover switch is required as a changeover switch at the time of failure. However, there is a problem that the cost is high.

As another measure, a manual switch is connected to the circuit system of a small relay that operates in response to a control signal from a microcomputer in parallel with the small relay and in series with an overheat protector. Then, there has been proposed a technique for controlling ON / OFF of a power relay of a main power supply circuit by operating the manual switch (Japanese Patent Laid-Open No. 4-93554). However, according to the technology described in this publication, there are two possible failure modes when the microcomputer fails: a mode in which a small relay is operated (relay ON) and a mode in which it is reversed (relay OFF). The
There is no problem in the relay OFF state among these modes, but if a failure occurs in the relay ON state,
The disadvantage of manual switches is that they are useless.

The present invention has been made in view of such circumstances, and even if a failure occurs in the circuit system of the microcomputer of the control device, it is easy to take measures against it, and the operation can be surely started. An object of the present invention is to provide an electric water heater that is simple and inexpensive in configuration for such backup.

[0008]

A structure for achieving the above object will be described with reference to FIGS. 1 and 2 corresponding to an embodiment. An electric heater 2 for heating water and a control device 3 for controlling the energization of the electric heater 2 are provided, and the control device 3 drives a small relay 21 for connecting / disconnecting the electric heater 2 to / from a power source 12 and a drive of the relay 21. In a water heater having a structure in which a microcomputer 3a that supplies a control signal is incorporated, a switch 4 for disconnecting the connection between the microcomputer 3a and the small relay 21 and a connection of the small relay 21 to the operation circuit 20 are possible. A temperature operation switch (for example, a bimetal type switch) 5 is provided. The temperature operation switch 5 is arranged at a position where the temperature of the hot water storage tank 1 can be sensed, and is connected to the drive circuit 23 of the small relay 21 in accordance with the temperature change of the tank 1 in the connected state to the operation circuit 20. Alternatively, it is characterized by being configured to provide a cutoff.

[0009]

When a failure occurs in the circuit system of the microcomputer 3a, the switch 4 is opened and the temperature operation switch 5 is connected to the operation circuit 20 of the small relay 21.
As a result, the signal from the microcomputer 3a is cut off, and the operation of the electric heater 2 is switched to the control by the opening / closing operation of the temperature operation switch 5.

Then, in the circuit connection after this switching,
Regardless of the failure mode of the microcomputer 3a, the small relay 21 operates reliably according to the opening and closing of the temperature operation switch 5.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a schematic configuration of an embodiment of the present invention.

The hot water storage tank 1 is provided with a water supply port 1a at the bottom and a hot water outlet 1b at the top. An electric heater 2 is mounted below the hot water storage tank 1. Further, a control sensor (temperature sensor) TH _C is arranged below the hot water storage tank 1, and the detection output of this sensor TH _C is input to the control device 3.

The controller 3 controls the start and stop of energization of the electric heater 2 based on the detection output of the control sensor TH _{C. As} shown in FIG.
a and the energization control unit 3b are provided.

The microcomputer 3a stores the boiling temperature setting value set by the operation of a remote controller (not shown), and the temperature information such as the stored setting value and the water temperature detection value by the control sensor TH _C. Is used to calculate the peak shift, and based on the calculation result, a control signal such as a signal to start energizing the electric heater 2 is supplied to the energization controller 3b.

The energization control unit 3b includes a power relay 11 connected in series to a main power supply circuit 10 which is an energization circuit for the electric heater 2 and a small relay 2 connected to an operation circuit 20.
1 is provided, and its small relay 21 is turned on / off in accordance with a supply signal from the microcomputer 3a, and the power relay 11 is turned on / off in accordance with this, thereby energizing and stopping the electric heater 2. Is configured.

The AC power supplies 12 and 22 connected to the above circuit system are 200V late-night power, and the power supply 23 is a DC power supply for driving the small relay 21. Further, the main power supply circuit 10 is connected with an overheat preventive device (bimetal type switch) 13 for preventing the temperature of the hot water in the hot water storage tank 1 from rising too high.

What should be noted in the embodiment of the present invention is that the switch (normally closed) 4 is connected in series to the signal supply line between the microcomputer 3a and the small relay 21, and the temperature operation switch 5 is used. Is located on the wall of the hot water storage tank 1 in the vicinity of the above-mentioned overheat preventive device 13.

The temperature operation switch 5 is, for example, a bimetal type switch and is opened / closed according to the temperature of the wall of the hot water storage tank 1, that is, the water temperature in the tank. The temperature used as the reference for the opening / closing operation is set to the boiling temperature (for example, 85 ° C.). Further, the temperature operation switch 5 is connected in series to the operation circuit 20 of the small relay 21 via the connector 6, but normally the connection is cut off.

Next, the operation of the embodiment of the present invention will be described. First, in the normal state, the switch 4 is closed, and
The connector 6 of the temperature operation switch 5 is removed and the operation circuit 2
Therefore, the small relay 21 operates in response to a signal from the microcomputer 3a, and the power relay 11 operates in response to the signal to control the energization of the electric heater 2.

When a failure occurs in the circuit system of the microcomputer 3a, the switch 4 is closed to cut off the connection between the microcomputer 3a and the small relay 21, and the connector 6 is connected to the temperature operation switch 5.
Is connected to the operation circuit 20. As a result, the electric heater 2
The operation of is switched to the control by opening / closing operation of the temperature operation switch 5, and the water temperature in the hot water storage tank 1 is heated to the boiling temperature: 85
When the temperature is below ℃, the temperature operation switch 5 is ON and the relay 2
Each of 1 and 11 is turned on, and the electric heater 2 is energized. When the temperature of the water in the hot water storage tank 1 rises to the boiling temperature due to heating by the heater, the temperature operation switch 5 is turned off, and the relays 21 and 11 are turned off.
It becomes FF and the electric power supply to the electric heater 2 is stopped.

[0021]

As described above, according to the electric water heater (energization control type) of the present invention, when the circuit system of the microcomputer fails, the switch is operated to switch between the microcomputer and the small relay. It is possible to switch the operation of the electric heater to control by opening and closing the temperature operation switch simply by disconnecting the connection and connecting the temperature operation switch (located in the hot water storage tank) to the operation circuit of the small relay. Even if a failure occurs, the operation can be restarted easily.

Moreover, the small relay operates reliably in accordance with the opening / closing operation of the temperature operation switch regardless of the failure mode of the microcomputer, so that the reliability of backup is high. Furthermore, since it can be implemented by adding about 2 to 3 parts such as a switch and a temperature operation switch, it is inexpensive at the time of practical use.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration of a control device 3 according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an embodiment of the present invention.

[Explanation of symbols]

1 Hot Water Storage Tank 2 Electric Heater 3 Control Device 3a Microcomputer 3b Energization Control Unit 10 Main Power Supply Circuit 11 Power Relay 12 Power Supply 20 Operation Circuit 21 Small Relay 23 Power Supply 4 Switch 5 Temperature Operation Switch 6 Connector TH _C Control Sensor

Claims (1)

[Claims] 1. A hot water storage tank (1), an electric heater (2) for heating water in the tank (1), and a control device (3) for controlling the energization of the hot water storage tank (1), the control device (3) comprising: , A small relay (21) for connecting and disconnecting the electric heater (2) to the power supply (12)
And a water heater having a structure in which a microcomputer (3a) for supplying a signal for controlling the drive of this relay (21) is incorporated, the connection between the microcomputer (3a) and the small relay (21) is cut off. Switch (4) and a temperature operation switch (5) that can be connected to the operation circuit (20) of the small relay (21) are provided, and the temperature operation switch (5) is used for the hot water storage The small relay (21) is arranged at a position where the temperature of the tank (1) can be sensed, and in accordance with the temperature change of the tank (1) in the connected state to the operation circuit (20).
An electric water heater configured to connect to or disconnect from the driving power source (23) of the electric water heater.