JPH0446337B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control device for an electric water heater that utilizes late-night power and moves the electricity to the heating element to the rear of the late-night power supply period. .

[Prior Art] A conventional energization control type electric water heater that utilizes late-night electricity will be explained with reference to FIG.

In FIG. 4, 1 is a hot water storage tank, and a heating element 2 is attached to the lower part of the tank.

3 is a temperature measuring means for measuring the water supply temperature and boiling temperature; 4 is a time switch that limits the time period of power supply to the heating element 2; 5 is a power source detector that detects whether the contact of the time switch 4 is ON or OFF. Means 6 is a hot water amount setting means for setting the amount of hot water required by the user; 7 is a necessary energization time H for the heating element 2 based on the output of the hot water amount setting means 6; an energization start time Hs;
A calculating means for calculating the boiling temperature T; 8 a timer means for counting the elapsed time based on the results of the calculating means 7; and 9 a heating element for controlling the heating element 2 based on the results of the calculating means 7 and the timer means 8. It is a means of body control.

Next, the operation will be explained with reference to the control flowchart shown in FIG.

First, as soon as the power is turned on, the confirmation of ON/OFF of time switch 4 in step 10 starts. At the same time as the time switch 4 is turned on, the timer means 8 clears the timer in step 11 and starts the timer operation.

Next, in step 12, the set amount of hot water in the hot water amount setting means 6 is confirmed. Next, in step 13, the temperature of the water supply is measured.

In steps 14 and 15, the boiling water temperature T and the required energization time H are calculated, respectively. Step 16
Then, the energization start time Hs (Hs = 8
-H) calculation is performed.

Next, in step 17, it is determined by the timer in step 11 whether or not the time Hs has elapsed since the time switch 4 was turned on.
When the Hs time has elapsed, the timer is stopped in step 18, and energization to the heating element 2 is started in step 19.

Next, in step 20, the temperature measuring means 3 measures the temperature of the water in the tank 1, and it is determined in step 21 whether or not this water temperature has reached the boiling water temperature T set in step 14. When the water temperature reaches the boiling temperature T, the power supply to the heating element 2 is stopped (step 22), and one boiling control is completed.

[Problem that the invention attempts to solve]

In this way, the conventional control device performs control to delay the energization of the heating element 2 after detecting that the contact of the time switch 4 is ON when moving the energization of the heating element 2 to the later part of the late-night power supply period. Was.

Since the ON detection of the contact of the time switch 4 was performed by a detection circuit that passed a very small current, for example, if foreign matter adhered to the contact of the time switch 4 or the contact surface corroded, the contact resistance would increase. , which can range from a few kiloohms to several tens of kiloohms.

As a result, there were problems in that the continuity of the contacts of the time switch 4 could not be detected and the boiling control could not be performed.

This invention was made to solve the above-mentioned problems.
The purpose of the present invention is to obtain a control device for an electric water heater that can control boiling even if ON operation cannot be detected normally.

[Means for solving problems]

A control device for an electric water heater according to the present invention includes a power supply detection means for detecting the operation of a time switch that limits the late-night power supply time zone, a timer means for counting time, and a result of the timer means and the power supply detection means. The present invention is provided with an abnormality determining means for determining an abnormality in the contacts of the time switch based on the above, and a heating element control means for controlling energization of the heating element.

[Effect]

The electric water heater control device according to the present invention forcibly connects the circuit so that the heating element control means can start energizing the heating element when the count value of the timer means reaches a value corresponding to a predetermined time. , the arc discharge at the time switch contacts destroys foreign matter adhering to the contacts, and the prescribed boiling is executed, and regular boiling control can be performed from the next time onwards.

〔Example〕

Hereinafter, a control device for an electric water heater according to the present invention will be explained.

FIG. 1 is an overall configuration diagram of an embodiment according to the present invention, and numerals 1 to 9 are completely the same as the conventional device described above.

Reference numeral 10 denotes an abnormality determination means for determining an abnormality in the contact of the time switch 4, and after detecting that the contact of the time switch 4 is OFF, it is determined for a certain period of time (for example, 16 hours).
If the ON operation cannot be detected even after the time has elapsed, the contact of the time switch 4 is determined to be abnormal, and a heating element is forcibly connected to the contact of the time switch to eliminate the abnormality in the contact.

FIG. 2 is a circuit diagram showing the electrical connections of the embodiment of FIG. 1.

In the figure, 23 is a microcomputer in the control circuit, including a CPU 24, a memory 25, and an input circuit 2.
6, an output circuit 27 and a timer circuit 28.

Reference numeral 29 denotes a heating element control circuit, which is composed of resistors 30 and 31, a transistor 32, and a relay 33. The coil 33a of the relay 33 is connected via a transistor 32 between the positive terminal +V and the GND terminal, and the transistor 32 is connected to the output circuit 27 via a resistor 30. The normally open contact 33b of the relay 33 is connected to the electrical circuit between the AC200V power source and the heating element 2 via the time switch 4.

34 is a temperature sensor that detects the temperature inside the hot water storage tank 1; 35 is a resistor connected in series with the temperature sensor 34 between the positive terminal +V and the GND terminal; these constitute the temperature measuring means 3.

36 is a variable resistor for setting the amount of hot water; 37 is a resistor connected in series with the variable resistor 36 between the positive terminal +V and the GND terminal; these constitute the hot water amount setting device 6.

38 is an analog multiplexer to which the variable resistor 36 and the detection output of the temperature sensor 34 are input;
Reference numeral 9 denotes an A/D converter that converts its output into a digital value, and a signal from this A/D converter 39 is sent to the input circuit 26 of the microcomputer 23.

40 is a power supply detection circuit, which includes resistors 41, 42,
It consists of a diode 43, a phototransistor 44, and a smoothing capacitor 45.

One end of the light receiving side 44b of the phototransistor 44 is connected to the resistor 42, and the other end is connected to the GND terminal. The other end of the resistor 42 is a positive terminal +
Connected to V.

The AC power on the secondary side of the time switch 4 is applied to this power supply detection circuit 40, and a half wave is passed through a diode 43 via a resistor 41. The opposite half wave is the light emitting side 44 of the phototransistor 44.
flows through a.

Therefore, when the time switch 4 is ON, a current flows through the light emitting side 44a of the phototransistor 44, and a current flows through the resistor 42 into the light receiving side 44b of the phototransistor 44.

In order to stabilize the voltage at this time, a smoothing capacitor 45 is provided, and this signal is sent to the input circuit 26 of the microcomputer 23 via an analog multiplexer 38 and an A/D converter 39 as a contact ON signal of the time switch 4. is input.

Conversely, when the time switch 4 is OFF, no current flows to the light emitting side 44a of the phototransistor 44, so the input signal to the input circuit 26 of the microcomputer 23 has the same voltage as the positive terminal +V at the contact of the time switch 4. Input as OFF signal.

Next, the operation of the above embodiment will be explained with reference to FIG.

Figure 3 shows the memory 2 of the microcomputer 23.
5 is a flowchart showing the heating element control stored in FIG.

First, when the power is turned on, it is determined whether the time switch 4 is ON or OFF in step 46 shown in FIG. If the time switch 4 is ON, then in step 47 the energization timer is cleared and at the same time a counting operation is started.

Next, in step 48, the user's setting of the required amount of hot water is confirmed. Next, in step 49, the temperature of the water supply is measured. Next, in step 50, the boiling water temperature T
Perform the calculation. Next, in step 51, the energization time H required to obtain the boiling water temperature T is calculated.

Next, in step 52, an energization start time Hs (Hs=8-H) for moving the energization time to the heating element 2 to the latter part of the midnight power supply time period is calculated. Here, 8 indicates the net power supply time period of the late night power supply time period.

In step 53, the time of the timer that started counting in step 47 is changed to the timer that started counting in step 47.
Comparing with the calculation result in step 2, the timer time is Hs
When the timer is reached, the timer is stopped in step 54, and energization to the heating element 2 is started in step 55.

Next, in step 56, the temperature of the water at the bottom of the tank 1 is measured, and in step 57, the temperature of the water is measured in step 5.
When the measured water temperature in step 56 reaches the calculated boiling water temperature T, the power supply to the heating element 2 is stopped in step 58.

During normal control, time switch 4 is ON
It turns off after 8 hours. Step 5
9 turns off time switch 4 after 8 hours have elapsed.
and step 6 at the same time as confirming OFF.
At 0, the anomaly detection timer for detecting an anomaly in the time switch 4 is reset and starts operation.

In normal time switch 4, after OFF
It should turn on again after 16 hours have passed. If it does not turn on after 16 hours, turn on time switch 4.
There is an abnormality.

In step 61, time switch 4 is turned OFF.
After that, it is determined that 16 hours have passed, and when 16 hours have passed, connect the heating element 2 to the contact of the time switch 4 in step 62, check whether the contact is ON or OFF (step 63), and if it is ON, in step 64 the heating element 2 is switched off. of
OFF and executes step 47, which is the start of control. If it is OFF in step 63, the heating element 2 is disconnected from the contact in step 65, and step 62 is executed again. Steps 62, 63, and so on until it is confirmed that the time switch is ON in step 63.
Step 65 is repeated, and when it is confirmed that the time switch is turned on, the heating element is turned off at step 64, and the boiling control operation from step 47 is performed. here,
Since the time required to repeat steps 62, 63, and 65 is several seconds, the net power supply time period in the midnight power supply time period in the calculation of step 52 may be approximately eight.

As a result, for example, even though the time switch 4 is ON, there may be foreign matter attached to its contacts or the contact surface may be corroded.
When the detection signal from the power supply detection circuit 40 is such that the OFF signal of the time switch 4 is input to the input circuit 26, the heating element 2 is forcibly connected as a load, causing an arc between the contacts. This generates an electric discharge, destroys corrosion on the contact surface and foreign matter adhering to it, and performs boiling, making it possible to perform normal boiling control from the next time onwards.

[Effects of the Invention] As described above, according to the present invention, when the count value of the timer means reaches a value corresponding to a predetermined time, the circuit is forcibly connected so that energization to the heating element can be started. However, since the power supply detection means is configured to detect the electrical ON state of the time switch contacts, the time switch contacts may become damaged due to foreign matter adhering to the contacts or corrosion on the contact surfaces.
Even if ON operation cannot be detected normally, daily boiling can be done reliably.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram showing one embodiment of the present invention, Fig. 2 is its main electric circuit diagram, Fig. 3 is a flowchart showing its operation, and Figs. 4 and 5 are conventional energization control. 1 is an overall configuration diagram showing an electric water heater and a flowchart showing its operation. In the figure, 1 is a hot water storage tank, 2 is a heating element, 4 is a time switch, 5 is a power supply detection means, 8 is a timer means, 9 is a heating element control means, and 10 is an abnormality determination means.

Claims (1)

[Claims] 1. In electric water heaters that move the electricity to the heating element to the rear of the late-night power supply period, the electrical contact of the time switch that limits the late-night power supply period
A power supply detection means for detecting ON and OFF, a timer means for counting time, an abnormality determination means for determining an abnormality in the contact of the time switch from the count value of the timer means and the detection value of the power supply detection means, and heating element control means for controlling electricity supply to the body, the timer means counts the elapsed time based on the detection of electrical OFF of the contact of the time switch by the power supply detection means, and the timer means When the count value reaches a value corresponding to a preset predetermined time, the circuit is forcibly connected so that the heating element control means can start energizing the heating element, and the power supply detection means contacts the time switch. 1. A control device for an electric water heater, characterized in that the control device is configured to detect an electrical ON state of the electric water heater.