JPH03226934A - Switch controlling circuit - Google Patents

Abstract

PURPOSE:To extend the total service life of a switch controlling circuit by installing a plurality of relay coils and on-off controlling one of the relay coils, and switching to another relay coils when the number of on-off cycle reaches a prescribed value. CONSTITUTION:A plurality of relay R1, R2 are connected to a load 2 in series and a counting part 4 which counts the contact switching signals and sends out a count up signal when the counted value reaches a prescribed value is installed. On of a plurality of relays R1, R2 is turned on and off based on the contact switching signals and the remaining relay is controlled to be continuous on state and a contact switching controlling part 5 to switch the relay which is controlled to be turned on and off to another relay based on the input of the count up signal is installed. In this way, the relays are cyclically changed on the input of each count up signal. Consequently, a switch controlling circuit having high durability is obtained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to power supply and application to loads that require large currents, such as heaters for electrically heated steam generators in steam saunas, steam heaters, etc. The present invention relates to a switch control circuit that repeatedly shuts off, and particularly relates to a switch control circuit that uses a relay as a switch element.

<Prior art> A switch control circuit using a relay generally includes a relay contact connected between a load and a power source, a relay coil that opens and closes the relay contact by excitation and demagnetization, and a contact switching signal input. and a contact switching control section that controls on/off of the relay coil based on the relay coil.

<Problems to be Solved by the Invention> In relay contacts that open and close very frequently and carry large currents, the contacts tend to weld relatively early due to discharge phenomena caused by bouncing and chattering that occur each time they open and close. This may cause contact failures such as poor contact or poor contact.

For example, in the case of a large-capacity heater with a load of 3KW, if the power source is 200V, the relay contact will be opened and closed using a large current of 15A. There are only a few dozen directions at most. Assuming that the number of openings and closings per day is 1000, the lifespan is only a few hundred milliseconds, and the maintenance cycle is quite short.

The present invention was devised in view of the above circumstances, and an object of the present invention is to provide a switch control circuit with excellent durability.

<Means for Solving the Problems> In order to achieve the above object, the present invention has the following configuration.

The switch control circuit of the present invention is a switch control circuit having a relay coil, a relay contact, a contact switching control section, and a counting section, and a plurality of the relay contacts are connected in series to a load. Yes, the relay coil opens and closes each of the multiple relay contacts individually, and the counter counts the contact switching signals and outputs a count amplifier signal when the count value reaches the set value. The contact switching control unit controls on/off of any one of the plurality of relay coils based on the input of the contact switching signal, and controls the remaining relay coils to be continuously on. , and the relay coil that is controlled on and off is switched to another relay coil based on the human power of the count-up signal, and all the relay coils that are controlled on and off in this way are switched every time the count-up signal is input. The relay coils are cyclically replaced.

<Effect> one The effects of the above configuration of the present invention are as follows.

Since all of the relay coils except for one relay coil are controlled to be in a continuous ON state, all of the remaining relay contacts except for one relay contact are closed.

Therefore, when the one relay coil is turned on, the corresponding one relay contact is also closed. Since all the relay contacts are connected in series, closing one of the relay contacts supplies current to the load, and opening cuts off the current. That is, only one relay contact opens and closes in response to the input of the contact switching signal.

When the contact switching signal reaches the set value and a count-up signal is output, the relay contact that was previously open and closed becomes continuously closed, and another relay contact opens and closes in its place. Become. When the next count amplifier signal is input while that relay contact is in the open/closed state, that relay contact becomes continuously closed, and another relay contact opens/closes.

Since the above operation is repeated cyclically every time the count amplifier signal is input, when looking at one relay contact, in addition to the period of opening and closing operation, there is a period of continuous closing, that is, a period of non-operation. During the rest period of one relay contact, one or more other relay contacts will control the opening/closing operation. In other words, by the time the total number of opening and closing times of one relay contact reaches its lifespan, the operation of supplying and cutting off power to the load is covered by one or more other relay contacts, so the overall lifespan is approximately The lifespan of one relay contact is multiplied by the number of relay contacts connected in series.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

Figure 1 is a block circuit diagram of a switch control circuit according to a first embodiment.

As shown in FIG. 1, j1 and load 2 are connected in series to the AC power source 1. Second two relay contacts rl+
Connected via r2. first relay contact r
A first relay coil R1 is provided to control the opening and closing of the second relay contact r2, and a second relay coil R2 is provided to control the opening and closing of the second relay contact r2.

A state determining section 3 is provided that determines the state of the load 2 and outputs a contact switching signal S, and is configured so that the contact switching signal S1 is guided to a counting section 4 and a contact switching control section 5.

The counting unit 4 has first and second relay contacts r, ,
A common setting value N regarding the number of times r2 is opened and closed is preset. The set value N is sufficiently smaller than the service life of the relay contacts rI+r2, which corresponds to the number of switching cycles E (
For example, it is set to about 1/100 to 1/1000.

This counting section 4 is configured to output a count amplifier signal S2 to the contact switching control section 5 when the count value of the contact switching signal S reaches a set value N.

When the first relay coil R=7 is controlled to be on/off (switched between excitation and demagnetization), the contact switching control unit 5 controls the second relay coil R7 to be in a continuous on state, while controlling the second relay coil R7 to be continuously on. When the first relay coil R2 is on/off controlled, the first relay coil R3 is controlled to be continuously on.

The on/off control for the first or second relay coils R, , R2 is such that, for example, the ON/OFF control is performed when the contact switching signal S1 is at the "H" level, and the ON/OFF control is performed when the contact switching signal S1 is at the "L" level.

Further, each time the contact switching control unit 5 receives the count-up signal S2 from the counting unit 4, the contact switching control unit 5 changes the target of on/off control from the first relay coil R1 to the second relay coil R2.
Further, the relay coil R2 is configured to alternate cyclically from the second relay coil R2 to the first relay coil R1.

Next, the operation of this first embodiment will be explained based on the time chart of FIG.

First, in the first stage, the contact switching control section 5 continuously turns on the No. 1 relay coil R1, and turns on the second relay coil R1.
2 is in a state of on/off control. The contact switching control section 5 excites the second relay coil R2 to close the second relay contact r2 every time the contact switching signal Sl from the state determining section 3 becomes "H" level, and outputs the contact switching signal S.
1 goes to "L" level, the second relay coil R2
is demagnetized to open the second relay contact r2.

On the other hand, the counting section 4 counts the rising of the contact switching signal S1 to the "H" level. When the count value reaches the set value N, the counting section 4 outputs the count amplifier signal S2 to the contact switching control section 5, and then is reset.

The contact switching control section 5 receives a count amplifier signal S.

When inputting , the first relay coil R is input.

is switched on and off, and the second relay coil R2 is switched to a state where it is continuously on-controlled. Then, each time the contact switching signal S becomes "H" level, the contact switching control unit 5 excites the first relay coil R, so that the first relay contact r,
is closed, and each time the contact switching signal S1 becomes "L" level, the first relay coil R5 is demagnetized and the first relay contact r1 is opened. The count value of counter 4 returns to the set value N.
When reaching this point and outputting the count-up signal S2, the contact switching control section 5 again switches to a state in which the first relay coil R is continuously turned on and the second relay coil R2 is controlled to be turned on and off.

Up to this point, the number of contact switching signals SlO output from the state determining section 3 is 2XN, whereas the number of opening and closing times of the first and second relay contacts rI+'Z is each half N.

As described above, the period in which the first relay contact r remains continuously closed and the second relay contact r2 operates to open and close, and
The relay contact r, opens and closes, and the second relay contact r2
The period during which the count amplifier signal S2 remains continuously closed is the period when the count amplifier signal S2 remains closed.
is repeated cyclically for each input. And contact switching signal S.

When the number of relay contacts rl+r2 reaches the number of times E can be opened and closed (however, E is an even number), the first and second
The number of times the relay contacts rI+r2 are opened and closed are both E/2, which is half the number of times E that the relay contacts can be used.

Further, when the above cyclic operation is continued and the number of contact switching signals S1 becomes 2XE, the number of opening/closing times of both the first and second relay contacts rI+rZ becomes E. Up to this stage, the number of times power is supplied/cut off to the load 2 is the same as the number of contact switching signals SI, which is 2XE. That is, while the number of times each relay contact rI+rZ can withstand switching is E, the switching operation for the load 2 is twice as many as 2xE times.

As shown in the waveform shown in the time chart, a time lag is provided to prevent both the first relay contact r and the second relay contact r2 from closing at the same time from the open state. This is because if both relay contacts rl+r2 are closed at the same time, there is a risk that an inrush current will flow through both relay contacts rl+r2 and cause both relay contacts 'l+rZ to deteriorate. By providing a time lag, inrush current waves will not flow to the relay contacts that are closed first, and deterioration can be suppressed. Control related to this 1-time lag is performed by the contact switching control section 5.

Figure 3 is a block circuit diagram of the switch control circuit according to the second embodiment.

This is the same as the first example in the first embodiment. For the series circuit of the second relay contact rl+rZ and the load 2, the third relay contact r, the fourth relay contact r4 and another load 2a
A third relay coil R1 and a fourth relay coil R4 are provided, which connect the series circuits in parallel with each other, and control the third and fourth relay contacts '3+r4 individually. is also controlled by the contact switching control section 5.

The operation of the switch control circuit of this second embodiment is as shown in the time chart shown in FIG. That is, 1st.
The second relay contact "I+rZ" operates in the same manner as in the first embodiment, and the third and fourth relay contacts r'l+r4 also operate in the same manner.

FIG. 5 is a block circuit diagram of a switch control circuit according to a third embodiment.

A series circuit of a first relay contact r, a second relay contact r2, and a first heater 2A is connected to the AC power supply 1, and a third relay contact r.

A series circuit of the fourth relay contact r4 and the second heater 2B is connected, and the primary winding 6a of the transformer 6 is further connected. A full-wave rectifier circuit 7 consisting of a diode bridge is connected to the secondary winding 6b of the transformer 6, and a smoothing capacitor 8, a thermistor 9, a thermocircuit 10, a counter 4, and a contact are connected between both ends of the full-wave rectifier circuit 7. A switching control section 5 and first to fourth relay coils R1 to R4 are connected.

The first and second heaters 2A and 2B are loads, and the thermistor 9 and thermocircuit 10 correspond to the state determining section 3.

FIG. 6 shows a heating system of an electrically heated steam generator used in a steam sauna.

A first heater 2A is provided across the bottom wall surface and peripheral wall surface of the evaporation tank 1), and a second heater 2B is similarly provided across the bottom wall surface and peripheral wall surface.

A thermistor 9 is provided in the steam chamber into which the steam from the evaporator tank 1) is guided. The reason why the first heater 2A and the second heater 2B are both provided on both the bottom wall surface and the peripheral wall surface of the evaporation tank 1) is to prevent scales adhering to the inside of the bottom wall surface and the inside of the peripheral wall surface of the evaporation tank 1). This is because the evaporation tank 1) is expanded and contracted by repeating power supply and cutoff to the heaters 2A and 2B, thereby peeling off the evaporation tank 1).

Next, the operation of the third embodiment will be explained.

When the power is turned on, the contact switching control unit 5 first starts continuous ON control of the first and third relay coils R, , R3, and after a time lag, turns on the second and fourth relay coils Rz, R4. Starts on/off control. As a result, the first to fourth relay coils R1 to R4 are closed, and power is supplied to the first and second heaters 2A and 2B.
The water stored in the evaporation tank 1) is heated and steam is supplied to the steam chamber.

As shown in FIG. 7, the thermistor 9 installed in the steam chamber
When the detected temperature reaches the lower limit temperature T of the dead zone, the thermo circuit 10 outputs a contact switching signal S1 of "H" level. The contact switching control unit 5 demagnetizes the fourth relay coil R4 and opens the fourth relay contact r4 based on the contact switching signal S1. As a result, the evaporation tank 1) is heated only by the first heater 2A.

When the temperature detected by the thermistor 9 reaches the upper limit temperature T2 of the dead zone, the thermo circuit 10 outputs the contact switching signal S at the °H'' level.
, and the contact switching control unit 5 demagnetizes the second relay coil R2 to open the second relay contact r2. The heating of the evaporator tank 1) is thereby interrupted. Thermistor 9
The detected temperature gradually decreases and reaches the lower limit temperature T1. Then, the second relay contact r2 is closed again, and the first
Heating is performed by the heater 2A, and the detected temperature rises.

However, when there are many bathers coming and going in the steam sauna room, the detected temperature may drop considerably even by the heating of the first heater 2A. When the detected temperature drops to the critical temperature T3, the thermo circuit 10 again outputs the contact switching signal S at "H" level, and the contact switching control section 5 excites the fourth relay coil R4 to switch the fourth relay. Close contact r4. Heating is thereby performed by the first and second heaters 2A2B.

As described above, when the power is turned on, the detected temperature is lower limit temperature T1.
Each time the upper limit temperature Tx and the critical temperature T are reached, the thermo circuit 10 outputs a contact switching signal S1 of "H" level. The counting unit 4 counts the contact switching signal S1 when the power is turned on and when the detected temperature reaches the lower limit temperature T1 as a count value regarding the second relay coil R2, and counts the contact switching signal S1 regarding the fourth relay coil R4. As a count value, the contact switching signal S when the detected temperature reaches the critical temperature T3 downward is counted. Therefore, the second
The count value for the fourth relay coil R2 advances quickly, and the count value for the fourth relay coil R4 advances slowly.

6 Figure 7 is a time chart over a relatively short period.
FIG. 8 is a time chart over a relatively long period. As shown in FIG. 8, when the count value of the second relay coil R2 by the counting section 4 reaches the set value N, the counting section 4 outputs the count-up signal St, and the contact switching control section 5 outputs the count-up signal St. The first relay contact r1 is opened and closed, and the second relay contact r2 is continuously turned on. Then, the count value regarding the first relay coil R3 becomes the set value N again.
When the count-up signal S2 is outputted when the count-up signal S2 is output, the contact switching control section 5 keeps the first relay contact r1 in a continuous ON state and opens and closes the second relay contact r2.

While the first and second relay contacts rr2 are cyclically switched, the third and fourth relay contacts r3+r4 are not switched. However, when the count value related to the fourth relay coil R4 eventually reaches the set value N2, the contact switching control section 5 opens and closes the third relay contact r, and keeps the fourth relay contact r4 in a continuous ON state. shall be. Then, the count value regarding the third relay coil R8 becomes the set value N2 again.
When the count-up signal S2 is outputted when the count-up signal S2 is output, the contact switching control section 5 keeps the third relay contact r3 in a continuous ON state and opens and closes the fourth relay contact r4.

While the third and fourth relay contacts r3r4 are cyclically switched, the first and second relay contacts rl+r2 are not switched. But again, the second relay coil R2
When the count value for the first relay reaches the set value N1, the contact switching control section 5 switches the first relay contact r1 to the opening/closing operation state.
The second relay contact r2 is turned on continuously.

Also in the third embodiment that performs such an operation, the set value N
+ By setting N2 relatively small,
The overall lifespan of the first and second relay contacts rl+r2 and the third and fourth relay contacts r'l+r4 is:
This is approximately twice as large as in the case of only the first relay contact r and the case of only the third relay contact r.

In each of the above embodiments, the number of relay contacts connected in series to one load (heater) was 2, but this number is 3.
It may be more than that.

<Effect of the invention> According to the present invention, the following effects are achieved.

One relay contact is in a non-operating state during the period when one or more other relay contacts are performing opening/closing operations, and such a non-operating period is repeated, so the total lifespan of multiple relay contacts is: Generally speaking, the lifespan of one relay contact multiplied by the number of relay contacts connected in series is the total length, and the end of the lifespan of each individual relay contact is essentially the same as the end of the total lifespan. Since they match, the total life of the switch control circuit can be greatly extended, especially when a large current is supplied. Therefore, the maintenance cycle also has a sufficiently large time span.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of a switch control circuit according to a first embodiment of the present invention, FIG. 2 is a time chart of the first embodiment, and FIG. 3 is a block circuit diagram of a switch control circuit according to a second embodiment of the present invention. A block circuit diagram, FIG. 4 is a time chart of the second embodiment, FIG. 5 is a block circuit diagram of a switch control circuit according to a third embodiment of the present invention, and FIG. 6 is a schematic configuration of an electrically heated steam generator. 7 and 8 are time charts of the third embodiment. 2.2a...Load 2A, 2B...Heater 4...Counting section 5...Contact switching control section R1, Rz...Relay coil rI+ r! ...Relay contact

Claims (1)

[Claims] (1) A switch control circuit including a relay coil (R_1, R_2), a relay contact (r_1, r_2), a contact switching control section (5), and a counting section (4), the relay contact (r_1, r_2) is a load (
2), the relay coils (R_1, R_2) open and close each of the plurality of relay contacts (r_1, r_2) individually, and the counter (4) receives a contact switching signal. , and outputs a count-up signal when the count value reaches a set value.The contact switching control section (5) controls multiple relay coils (R_1
, R_2) is controlled on/off based on the input of the contact switching signal, and the remaining relay coils are controlled to be continuously on, and based on the input of the count-up signal. The relay coil to be controlled on and off is switched to another relay coil, and the relay coil to be controlled on and off is switched in size for all relay coils (R_1, R_2) each time a count-up signal is input. A switch control circuit characterized in that the switch is switched to a click.