JPH045900B2 - - 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. .

[Conventional technology]

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; and 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; energization start time H _s ;
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, confirmation of whether time switch 4 is ON or OFF starts in step 10. 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
Now, the energization start time H _s for moving the energization to the heating element 2 to the later part of the late night power supply time period is calculated.

Next, in step 17, it is determined by the timer in step 11 whether H _s has elapsed since the time switch 4 was turned on, and H _{s is} determined.
When the 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 seeks 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.

Detection of the ON contact of the time switch 4 was performed by a detection circuit that flows a very small current, so if foreign matter adheres to the contact of the time switch 4 or the contact surface corrodes, the contact resistance increases. , which can range from a few kiloohms to several tens of kiloohms.

Therefore, there were cases where continuity of the contacts of the time switch 4 could not be detected and boiling control was not performed.

In addition, the late-night power supply period is usually 8 hours, and the remaining time is off, but the time setting of time switch 4 is set visually on a rough scale, and errors may occur due to the setting. there is a possibility.

Therefore, even if boiling control was attempted using a separate timer, there would be a deviation due to setting errors in the time switch 4, resulting in problems such as control not being synchronized with the time switch 4.

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 time switch that limits the time period during which power is supplied to a heating element, a power source detection means that detects the operation of this time switch, a timer means that counts elapsed time, and An abnormality determination means for determining an abnormality of the time switch based on the results of the timer means and the power supply detection means, and a heating element control means for forcibly connecting the heating element based on the abnormality determination output of the abnormality determination means. It is.

[Effect]

The electric water heater control device in this invention detects an abnormality in the time switch contact and turns the contact ON.
After a certain period of time has elapsed, a load is forcibly connected to the contact, and the arc discharge at the contact destroys any foreign objects on the contact, and the specified boiling is carried out. From next time onwards, regular boiling control will be performed. be able to do so.

〔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 normal control such as computation necessary for forced boiling is performed.

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.
7. It has a timer circuit 28.

Reference numeral 29 denotes a heating element control circuit, which is formed from resistors 36 and 31, a transistor 32, and a relay 33. The coil 33a of the relay 33 is connected between the positive terminal +V and the GND terminal via the transistor 32, and the transistor 32 is connected to the resistor 30.
It is connected to the output circuit 27 via. The normally open contact 33 of the relay 33 is connected to the electrical circuit between the AC 200V 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 detection outputs of the variable resistor 36 and the temperature sensor 34 are input;
39 is an A/D that converts the output into a digital value.
The signal of 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 attached, and this signal is inputted as a contact ON signal of the time switch 4 to the input circuit 26 of the microcomputer 23 via an analog multiplexer 38 and an AD converter 39. Ru.

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 of the switch 46 shown in FIG. 3 is ON or OFF. If the swim 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, the energization time H required to obtain the boiling water temperature T calculated in step 51 is calculated.

Next, in step 52, an energization start time _Hs for moving the energization time to the heating element 2 to the latter part of the late night power supply time period is calculated. Here, 8 indicates the net power supply time during 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 H _s
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, and 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 17 hours have passed, and when 17 hours have passed, the abnormality detection timer is stopped in step 62.

Next, in step 63, the hot water amount setting is automatically set to the "maximum" capacity, and the process is executed again from step 55.

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. Electrical discharge is generated to destroy corrosion and attached foreign matter on the contact surface, and boiling is performed, and normal boiling control is possible from the next time onwards.

If 17 hours have not elapsed in step 61, it is determined in step 64 whether the time switch 4 is ON or OFF, and if it is ON, step 47 is executed, and if it is OFF, step 61 is executed.

〔Effect of the invention〕

As described above, according to the present invention, if power cannot be detected due to an abnormality in the contacts of the time switch even after entering the midnight power supply period, the heating element is forcibly connected to the contacts of the time switch after a certain period of time has elapsed. With this configuration, even if the ON operation of the time switch setting cannot be detected correctly due to foreign matter adhering to the contacts or corrosion on the contact surfaces, daily boiling can be performed reliably.

In addition, even if there is a slight error in the time contact of the time switch, the timer is linked to the operation of the time switch, so there is no difference in boiling, and control is possible in synchronization with the time switch. be.

[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)

[Scope of Claims] 1. In an electric water heater in which the power supply to the heating element is moved to the later part of the late night power supply time period, a time switch that limits the power supply time period to the heating element, and an ON contact point of the time switch. , OFF
a timer means for counting elapsed time; an abnormality determining means for determining whether there is an abnormality in the contact of the time switch from the detected values of the timer means and the power supply detecting means; heating element control means for forcibly connecting the heating element when the determination is made;
At the same time as OFF, the elapsed time is counted and the contact is turned off.
Even when it is time to turn on, the power detection means is a contact point 2.
A control device for an electric water heater, characterized in that the control device for an electric water heater is configured to forcibly connect a heating element in a state where the supply of late-night electricity to the next side cannot be detected. 2. The control device for an electric water heater according to claim 1, wherein the power source detection means is configured to be detected by a load circuit on the secondary side of the contact of the time switch. . 3. The control device for an electric water heater according to claim 1, wherein the timer means and abnormality determination means are constituted by a microcomputer.