JPH0481705B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a method for detecting an abnormality in a hot water storage type water heater that always supplies hot water at a constant temperature by controlling a heating element included in the hot water storage tank. It is related to.

[Conventional technology]

FIG. 5 is a configuration diagram showing a conventional water heater,
In the figure, 1 is a hot water tank that always stores a certain amount of hot water, 2 is a faucet that supplies water to this hot water tank 1,
3 is attached to this faucet 2, and the hot water tank 1
4 is an overflow pipe that discharges excess hot water to prevent the hot water tank 1 from overflowing if the water level cannot be maintained at a constant value due to an abnormality in the ball tap 3. , 5 is an electric heater as a heating element placed at the bottom of the hot water tank 1, 6 is a temperature fuse connected in series to the electric heater 5, and 7 is a heating element for directing the water from the faucet 2 into the hot water tank 1. A water conduit pipe leading to the vicinity of the electric heater 5; 8 is a temperature sensor that outputs an electric signal corresponding to the temperature of hot water in the hot water tank 1 using, for example, a thermistor whose resistance value changes depending on the temperature; 9 is a hot water tank 1, a water faucet for taking out hot water from the interior as needed; 10, a temperature control means for comparing the output signal of the temperature sensor 8 with a reference value to generate information for controlling the heat generation of the electric heater 5; 11; 12 is a relay circuit that operates according to the output information of the temperature control means 10 and controls on/off of the power supply 11 that is supplied to the electric heater 5.

Next, the operation will be explained. First, the faucet 2 is opened and the hot water tank 1 is filled with water.
In this case, when the water level in the hot water storage tank 1 rises and the ball tap 3 reaches a predetermined position, the water supply from the faucet 2 is stopped by its action. Even if the water supply is not stopped even if the water level exceeds a predetermined level for some reason, the excess water will be discharged from the overflow pipe 4 and will not overflow from the hot water storage tank 1. Here, when temperature control by the temperature control means 10 is started, since there is still water in the hot water storage tank 1, the electric signal from the temperature sensor 8 is much lower than the reference value.
The temperature control means 10 outputs information for turning on the relay of the relay circuit 12. Therefore, the power supply 11
is supplied to the electric heater 5 via this output circuit 12, and the electric heater boils the water in the hot water tank 1. When the temperature of the hot water in the hot water tank 1 rises, the level of the electrical signal output from the temperature sensor 8 also rises, and when the temperature of the hot water rises to a predetermined value, the level of the output signal from the temperature sensor 8 also reaches the reference value. When the temperature control means 10 detects that the output signal of the temperature sensor 8 has reached the reference value, it outputs information to the output circuit 12 to turn off the relay. Therefore, the power supply 11 supplied to the electric heater 5 via this output circuit 12 is cut off, and the electric heater 5 stops generating heat.

Here, when the tap of the hot water tap 9 is opened and hot water is used, the water level in the hot water tank 1 decreases and the ball tap 3 is lowered from a predetermined position, and water supply from the tap 2 is started by this action. Ru. Since this supplied water has a low temperature, it lowers the temperature of the hot water stored in the hot water storage tank 1, and therefore the level of the electrical signal output from the temperature sensor 8 also decreases. When detecting that the level of the output signal of the temperature sensor 8 has become lower than the reference value, the temperature control means 10 outputs information to turn on the relay, and the relay circuit 12 turns on the power to the electric heater 5 based on this output information. 11 supply will be resumed. At this time, the water from the faucet 2 is led to the vicinity of the electric heater 5 at the bottom of the hot water tank 1 through the water conduit 7, and is efficiently heated. As in the case described above, the supply of power 11 to electric heater 5 is interrupted until the temperature of hot water in hot water storage tank 1 reaches a predetermined value and the level of the output signal of temperature sensor 8 reaches a reference value.
In addition, even if the hot water in the hot water storage tank 1 is not used, the same process as in the above case will proceed even if the hot water cools down after a long period of time, and the temperature of the hot water in the hot water storage tank 1 will be maintained at a predetermined value. It will be done.

[Problem to be solved by the invention]

Conventional water heaters are configured as described above, so abnormalities such as relay welding in the output circuit that controls the energization of the heating element can be detected by using a current sensor to detect whether or not current is flowing directly to the heating element. This is done by making judgments.

However, in this configuration, the current sensor and the signal from the current sensor are processed by a microcomputer (hereinafter referred to as
A signal converter is required to convert the signal so that it can be processed by a microcomputer (referred to as a microcomputer), which poses problems of increasing costs and taking up space.

This invention was made to solve the above-mentioned problems, and by relying on software to detect abnormalities in the output circuit, it is possible to reduce costs and downsize the device. The purpose is to obtain a detection method.

[Means to solve the problem]

The abnormality detection method for a water heater according to the present invention is based on the condition that the hot water temperature does not decrease even after a certain period of time has elapsed despite the temperature control function unit outputting heat generation stop information of the heating element. This is considered abnormal.

[Effect]

The diagnostic function unit in this invention is dependent on hardware by determining that there is an abnormality if the water temperature does not drop even after a certain period of time has passed despite the output of heat generation stop information of the heating element. It is possible to detect abnormalities such as welding of relay contacts without having to do so, making it possible to reduce costs and downsize the device.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a water heater that implements the abnormality detection method of the present invention will be described below with reference to the drawings. In Figure 1, 1 is a hot water tank, 2 is a water tap, 3 is a ball tap, 4 is an overflow pipe, 5 is an electric heater, and 6 is a water tap.
is a temperature fuse, 7 is a water pipe, 8 is a temperature sensor,
Reference numeral 9 indicates a hot water tap, and reference numeral 12 indicates a relay circuit, which are the same as or equivalent to those of the conventional circuit with the same reference numerals in FIG.
Further, in FIG. 1, illustrations of ancillary circuits of the temperature sensor 8, a power source 11 for supplying the electric heater 5, etc. are also omitted.

14 is a drain pipe provided at the bottom of the hot water storage tank 1 to discharge all the stored hot water; 15 is a thermal valve attached to this drain pipe 14 to control draining/stopping; 16 is the aforementioned This is a thermal valve that is attached to the water faucet 2 in place of the tap to control the water supply/stop, and the relay circuit 12 not only controls the energization of the electric heater 5 but also controls these thermal valves 15 and 16. It is slightly different from the conventional method in the way it is carried out. Further, 17 is a temperature control function that generates information for controlling the heat generation of the electric heater 5 as a heating body based on the output signal of the temperature sensor 8;
8 is a calendar function that outputs information such as the current date, time, and day of the week while ticking; 19 is a first and second calendar function in which the usage mode of the water heater is preset as shown in Fig. 2; an operation control function that has two schedule tables 30 and 31, and controls operation/stop of the temperature control function 17 using information output from the calendar function 18 while referring to information set in both of these schedule tables; , 20 is a diagnostic function for diagnosing an abnormality in the electric heater 5 and the output circuit 12 based on the output information of the temperature control function 17 and the output signal from the temperature sensor 8, and 21 is the temperature control function 17 and a calendar function. 18, Operation control function 19, Diagnosis function 20
22 is an input circuit that converts the output signal of the temperature sensor 8 into information that can be processed by the microcomputer 21; 24 is an input circuit through which the user inputs information to the microcomputer 21; This is a man-machine interface using a console or the like for displaying output information from 21.

Next, the operation will be explained. Here, FIG. 3 is a flowchart showing the operating procedure of the operation control function 19. First, in step ST1, it is checked whether today is the designated day for drainage. That is, the operation control function 19 refers to the first schedule table 30 shown in FIG.
The day of the week information sent from Detect and step
Execute wastewater treatment in ST3. That is, step
In ST2, the time information sent from the calendar function 18 indicates that the start time of wastewater treatment set in the wastewater column of the second schedule table 31 shown in FIG. 2b has passed "4:30". When detected, in step ST3, the operation control function 19 outputs information to the relay circuit 12 to control the relay, open the thermal valve 15, and close the thermal valve 16. As a result, the hot water (water) remaining in the hot water tank 1 is discharged from the drain pipe 14, and since no water is supplied from the faucet 2, the hot water tank 1 becomes empty. Thereafter, when the end time "5:30" set in the drainage column of the second schedule table 31 arrives, the operation control function 19 finishes the drainage treatment in step ST3 and sends information to the relay circuit 12. The thermal valve 15 is closed and 16 is opened. Therefore, water supply from the faucet 2 is started, and the hot water tank 1 is filled with water to the level at which the ball tap 3 reaches a predetermined position.

Next, the day of the week information from the calendar function 18 is flagged as "1" in the clinical holiday column of the first schedule table 30. Steps to check whether the date falls on a day of temporary closure such as a public holiday.
Performed at ST4, and if it is a temporary holiday, step
At ST5, the corresponding flag in the temporary closure column of the first schedule table 31 is cleared to "0" and the operation for that day is ended. If it is not a temporary holiday, in step ST6, a check is made as to whether or not the timer to be used is a timer based on the day of the week information, with reference to the first schedule table 30, and the column for that timer is checked. Based on the flag “1” set in
If it is Friday, the timer is selected in step ST7 and the process proceeds to step ST10. In other cases, it is checked in step ST8 whether the timer used is a timer, and based on the flag "1" set in the timer column, if the day of the week information is Saturday, the timer is selected in step ST9. Then, the process proceeds to step ST10, and if it is Sunday, no timer selection is made and the operation for that day is ended. In step ST10, it is determined whether the time information sent from the calendar function 18 has reached the timer column of the second schedule table 31 or the start time "6:30" set in the timer column. If the operation control function 19 detects that the start time has passed, the operation control function 19 outputs information instructing the temperature control function 17 to start temperature control in step ST11, and starts the operation for that day.

At this point, there is still water in the hot water tank 1, so
The hot water temperature measured by the temperature sensor 8 is much lower than the set hot water temperature, the output information from the input circuit 22 does not reach the reference value, and the temperature control function 17
The information for turning on the relay 2 is output, and the electric heater 5 is driven to boil the water in the hot water tank 1. When the temperature of the hot water in the hot water storage tank 1 rises, the level of the electrical signal output by the temperature sensor 8 also rises, and when the output information of the input circuit 22 reaches the reference value, the temperature control function 17
outputs information to the relay circuit 12 to turn off the relay, and the electric heater 5 stops generating heat when the power supply is cut off.

Input circuit 2 that converted the output signal of temperature sensor 8
When the temperature control function 17 detects that the temperature of the hot water stored in the hot water storage tank 1 has decreased by more than the differential width from the set hot water temperature based on the information from the hot water storage tank 1, the temperature control function 17 outputs information to turn on the relay, and the temperature control function 17 outputs information to turn on the relay. circuit 1
2 restarts power supply to the electric heater 5 based on this output information.

When the water temperature in the hot water storage tank 1 reaches the set water temperature, the temperature control means 17 outputs information to the relay circuit 12 to supply power to the electric heater 5, as in the case described above. stop. For such temperature control, if the time information from the calendar function 18 is from Monday to Friday when the timer is selected, the end time "18:30" set in the timer column of the second schedule table 31 is used. ”, and on Saturday when the timer is selected, the end time “12:30” set in the timer column of the second schedule table 31 will continue.
This will continue until a decision is made in ST12.

Here, the contents of the first and second schedule tables 30 and 31 are set using the keyboard of the man-machine interface 24 or the like in accordance with the usage pattern of the water heater by the user.

Such temperature control is self-diagnosed by the diagnostic function section 20, and if an abnormality is detected, the user is notified by an alarm. FIG. 4 is a flowchart showing the operating procedure of this diagnostic function section 20. At the start of processing, initial settings are first made in step ST21, and the counter for relay welding detection is set.
Clear CNT to “0”. Next, step
In ST22, it is determined whether the temperature control function 17 is sending out information instructing to drive the electric heater 5 to the relay circuit 12.

As a result of the judgment in step ST22, temperature control function 1
7 has not outputted information instructing the driving of the electric heater 5 to the relay circuit 12, the process moves to step ST23 and enters a routine for self-diagnosing whether the relay contacts of the output circuit 12 are welded.

In the relay welding self-diagnosis routine, first, in step ST23, the counter CNT is incremented, and then, in step ST24, the current water temperature PV measured by the temperature sensor 8 and the set hot water temperature SP are incremented by 1.
Compare with the value after deducting ℃. As a result, the water temperature
If PV is larger, the process moves to step ST25, and in step ST25, it is confirmed that one hour has not elapsed since the time when the counter CNT started counting.
Return processing to step ST23. Thereafter, this process is repeated, and if the hot water temperature PV does not drop below (SP-1) even if it is detected in step ST25 that one hour has passed, the relay contacts of the relay circuit 12 are welded. Steps to process
Proceeding to ST26, the diagnostic function unit 20 sends an alarm suggesting welding of the relay contacts to the man-machine interface 24, and notifies the user by a buzzer, light-emitting display, etc.

Before step ST25 detects that one hour has passed, the water temperature PV is determined at step ST24 (SP-1).
If there is a fall, the process goes to step ST27.
The value obtained by subtracting the differential width Td from the hot water temperature PV and the reference hot water temperature SP, that is, the hot water temperature (SP - Td ), and the process returns to step ST23 and repeats the process until the measured hot water temperature PV is smaller. this is,
This is a process to eliminate the effect of a temporary drop in the temperature of hot water caused by water being supplied into the hot water tank 1 from the faucet 2.

Only when the hot water temperature PV becomes less than (SP-Td),
It is determined that the relay of the relay circuit 12 is normal,
The process advances from step ST27 to step ST28, where the counter CNT stops counting and the process proceeds to step ST28.
The count value is cleared to "0" in ST29, and the process returns to step ST22 via step ST30.

The above relay welding self-diagnosis routine continues until step ST30 detects the end of temperature control.
It is executed repeatedly as appropriate.

Although the above embodiment uses a thermal valve to prevent the water hammer phenomenon, other electromagnetic valves may be used instead.

In addition, the capacity of the heating element,
Determined by the size of the hot water tank, heat radiation coefficient, etc.
In the above embodiment, this fixed time is measured by counting up, but it can also be measured by counting down or by comparing the time when the routine is entered and the current time.

〔Effect of the invention〕

As described above, according to the present invention, the diagnostic function section included in the microcomputer determines that the hot water temperature does not decrease even after a certain period of time has elapsed despite the output of heat generation stop information of the heating element. By determining that the relay circuit is abnormal, it is possible to detect an abnormality in the relay circuit without depending on the hardware, which has the effect of reducing costs and downsizing the device.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing a water heater according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing a schedule table, Fig. 3 is a flowchart showing the operating procedure of the operation control function section, and Fig. 4 is a diagnostic diagram. FIG. 5 is a flowchart showing the operating procedure of the functional parts, and is a configuration diagram showing a conventional water heater. 1 is a hot water storage tank, 5 is a heating element (electric heater), 8 is a temperature sensor, 12 is a relay circuit, 17 is a temperature control function section, 20 is a diagnostic function section, and 22 is an input circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A hot water storage tank for storing hot water boiled by a heating element, a temperature sensor for measuring the temperature of the hot water in the hot water storage tank, and generating information for controlling heat generation of the heating element based on an output signal of the temperature sensor. a relay circuit that opens and closes the energizing path of the heating body according to output information of the temperature control function section; a calendar function that ticks time and outputs information such as date, time, day of the week, etc.; In a water heater having an operation control function that controls operation/stop of the temperature control function using information output from the function, a certain period of time after the temperature control function unit outputs information on stopping heat generation of the heating element. A method for detecting an abnormality in a hot water supply apparatus, characterized in that when the temperature of the hot water does not decrease over time, a diagnostic function section determines that an abnormality has occurred in the relay circuit.