JP2675237B2 - Relay drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relay drive circuit, and more particularly to a relay drive circuit which has a simple circuit structure and can be manufactured at low cost.

[0002]

2. Description of the Related Art FIG. 3 is an electric circuit diagram showing a configuration of a conventional relay drive circuit used in, for example, a combustion safety device for a boiler.

In the figure, a relay control circuit 48
Is a circuit for identifying whether or not the ignition sequence for igniting the boiler has been normally executed. The relay control circuit 48 outputs the relay drive signal DS to the relay drive circuit 52 only when it determines that the ignition sequence is normally executed. In addition, the relay control circuit 4
When determining that the ignition sequence has not been normally executed, 8 outputs an alarm signal AS to the alarm drive circuit 49.

The alarm drive circuit 49 receives the alarm signal AS from the relay control circuit 48, and then the inverter 5
The signal of'H 'level is output to 0.

Further, the alarm drive circuit 49 is provided with a disconnection check circuit 51.

The disconnection check circuit 51 is a bimetal SS.
It is connected to the plus side power source Vcc through H and the first switch contact SSW1b.

On the other hand, the relay drive circuit 52 outputs a pulse signal of a predetermined repetition frequency to the inverter 5 based on the relay drive signal DS supplied from the relay control circuit 48.
Output to 3. The output terminal of the inverter 53 is connected to one end of the load drive relay coil RK.

A series circuit of a diode D1 and a diode D2 is connected in parallel to the load driving relay coil RK. Further, a series circuit of a capacitor 54 and a resistor 55 is connected in parallel to the load driving relay coil RK.

The positive electrode of the capacitor 56 is connected to the connection point between the diode D1 and the diode D2 connected in series. The negative electrode of the capacitor 56 is connected to the ground.

A voltage is applied to the output terminal of the inverter 53 from the positive power source Vcc through the series circuit of the first switch contact SSW1b and the resistor 57.

FIG. 4 is an electric circuit diagram showing the configurations of the load circuit and the alarm circuit.

In the figure, K is a contact which is turned on / off by the load driving relay coil RK, and SSW.
Reference numeral 2a is a second switch contact which is turned on / off by the bimetal SSH. An electromagnetic valve 58 for fuel supply is connected to the contact K, and the second switch contact SSW2 is connected.
An alarm circuit 59 is connected to a. When the contact K or the second switch contact SSW2a is closed,
An AC voltage is applied from an AC power supply 60 to the electromagnetic valve 58 or the alarm circuit 59.

Next, the operation will be described.

First, when the power is turned on, the plus side power source V
The charging current i0 flows from cc through the first switch contact SSW1b and the resistor 57, and energy is stored in the capacitor 56.

When the ignition sequence is executed normally, the relay drive signal D is output from the relay control circuit 48.
S is output to the relay drive circuit 52, which causes the inverter 53 to output a pulse signal having a predetermined repetition frequency.

As a result, the output of the inverter 53 is'L '.
During the level period, the energy stored in the capacitor 56 is released, and a part of this energy moves to the capacitor 54 via the diode D1 and flows into the inverter 53 as a current i1 to load the load drive relay coil RK. Get excited. The energy stored in the capacitor 56 becomes zero by being released.

Next, while the output of the inverter 53 is at the'H 'level, the energy stored in the capacitor 54 causes the current i3 to flow through the load drive relay coil RK, thereby maintaining the excitation of the load drive relay coil RK. .

On the other hand, the output current of the inverter 53 and the charging current i0 flow into the capacitor 56 to accumulate energy.

Since the relay drive signal DS is a pulse signal having a predetermined repetition frequency, energy storage in the capacitor 56 and energy release from the capacitor 56 are repeated, and as a result, the load drive relay coil R
The load driving relay is operated by the current i1 flowing through K.

As described above, when the ignition sequence is normally executed, the excitation of the load driving relay coil RK is maintained, the contact K is closed, and the AC voltage is applied to the electromagnetic pulse 58.

On the other hand, when an abnormality occurs in which the ignition sequence is not normally executed, the relay control circuit 48 outputs the alarm signal AS to the alarm drive circuit 49, which causes the inverter 50 to output the signal of the "L" level. , The positive side power supply Vcc to the first switch contact SSW1
A current i4 flows to the bimetal SSH via b, and the bimetal SSH is heated by this current, and after a lapse of a predetermined time, the first switch contact SSW1b is opened and the second switch contact SSW1b is opened.
The switch contact SSW2a is closed.

When the first switch contact SSW1b is opened, sufficient energy is not stored in the capacitor 56 from the positive power supply Vcc, so that the load drive relay coil RK cannot be excited and the second switch contact SSW2a is closed. The alarm circuit 59 operates and an alarm is issued.

Note that the alarm signal AS needs to be manually released by the operator, and when the alarm signal AS is released, the alarm drive circuit 49 sends an "L" level signal to the input of the inverter 50. To output the current i4 to zero,
After a while, the first switch contact SSW1a and the second switch contact SSW2a are returned to their original states.

In addition, at the time of this releasing operation, the alarm drive circuit 49 outputs an'H 'level disconnection check signal to the inverter 50, and this signal is disconnected.
A disconnection check in the vicinity of the bimetal SSH is performed depending on whether or not the wire returns via 1.

[0025]

As described above, in the conventional relay drive circuit, a circuit for driving and controlling the load drive relay coil RK and a circuit for operating the alarm circuit are separately provided. In order to further enhance safety, the load drive relay coil RK is excited by a pulse signal to turn on / off the contact K, so that the circuit configuration becomes complicated and the cost is high. However, there is a problem in that the size of the circuit itself becomes large.

Therefore, an object of the present invention is to provide a relay drive circuit which, while ensuring safety, simplifies the circuit structure, has a compact structure which can be housed in a narrow space, and further can reduce the cost.

[0027]

A relay drive circuit according to the present invention is supplied from a power supply via a relay drive signal control means for outputting a relay drive signal which is an ON / OFF signal, a load drive relay and an alarm relay. Energy storage means for accumulating energy, load drive relay trigger means for operating the load drive relay using the energy accumulated by the energy storage means by using a relay drive signal as a trigger, and the load drive relay trigger means. By the load drive relay holding means for holding the operated load drive relay by the energy supplied from the power source, the alarm relay drive means for driving the alarm relay when the relay drive signal is off, and the load drive relay holding means. By driving the retained load drive relay to drive the above alarm relay. Is obtained by a reset load drive relay reset means.

The relay drive circuit according to the present invention includes a relay drive signal control means for outputting a relay drive signal which is an on / off signal, a flame detection means for outputting a flame detection signal, a load drive relay and an alarm relay. Energy storage means for storing energy supplied from a power source via a load drive relay trigger means for operating the load drive relay with the energy stored by the energy storage means triggered by the relay drive signal. Load drive relay holding means for holding the load drive relay by the energy supplied from the power source, and an alarm relay for driving the alarm relay when the relay drive signal is off and no flame detection signal is output from the flame detection means. The load is shielded from the power supply by driving the driving means and the alarm relay. A load shedding unit for, in which a relay reset means for resetting the alarm relay which is driven by a retained load driving relay and the alarm relay driving means by the load drive relay holding means.

[0029]

In the relay drive circuit according to the present invention, the energy supplied from the power supply via the load drive relay and the alarm relay is stored in the capacitor, and the relay drive signal which is the ON / OFF signal output by the relay drive signal control means is output. Using the energy stored in the capacitor as a trigger, the load drive relay is operated, and then the load drive relay is held by the energy supplied from the power supply. Further, when an abnormality occurs, the relay drive signal control means turns off the relay drive signal, and the alarm relay driven as a result releases the holding of the load drive relay.

In the relay drive circuit according to the present invention, the energy supplied from the power source via the load drive relay and the alarm relay is stored in the capacitor, and the relay drive signal is used as a trigger to drive the load with the energy stored in the capacitor. The relay is activated, so that the load drive relay is now held by the energy supplied by the power supply. When the relay drive signal is off and the flame detection signal is not output from the flame detection means, the alarm relay is driven to disconnect the load from the power supply. Further, the alarm relay driven by the alarm relay drive means is reset by the relay reset means to return to the initial state.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the relay drive circuit of the present invention will be described below with reference to the drawings.

FIG. 1 is an electric circuit diagram showing the structure of a relay drive circuit used in a combustion safety device such as a boiler.

In the figure, the AC power supply 1 is connected to one terminal of a contact K2b.

The other terminal of the contact K2b is connected to the common terminal of the contact K1c. The contact K2b is a contact that opens when the second relay coil K2 is excited. The contact K1c is a contact that operates when the first relay coil K1 is excited.

The load 2 is an electromagnetic valve for supplying combustion and is connected between the normally open terminal of the contact K1c and the common line COM.

The normally closed terminal of the contact K1c is a diode D1.
And a resistor R1 connected in series to a series circuit of the first relay coil K1, the second relay coil K2, and the capacitor C2.

A series circuit of a resistor R2 and a capacitor C3 is connected in parallel to the first relay coil K1. First
A discharge circuit 3 including a diode D2 and a diode D3 is connected to the relay coil K1 and the second relay coil K2.

A diode D4 is connected between the connection point of the diodes D2 and D3 of the discharge circuit 3 and the common line COM. In addition, diode D2 and diode D3
A capacitor C1 is connected between the connection point of and the normally open contact of the contact K1c.

On the other hand, the relay control circuit 4 is a circuit for identifying whether or not the ignition sequence for igniting the boiler has been normally executed. The relay control circuit 4 is a circuit that outputs the relay drive signal DS of the “H” level to the inverter Q1 only when it is determined that the ignition sequence is normally executed.

The inverter Q1 is a circuit which inverts the relay drive signal DS and supplies it to the connection point between the first relay coil K1 and the second relay coil K2.

Next, the operation will be described.

First, when the power source is turned on, the half-wave rectified charging current i0 is supplied from the AC power source 1 to the contact K2b → contact K1.
The normally closed terminal of c → diode D1 → resistor R1 → first relay coil K1 → second relay coil K2 → capacitor C2 flows through the path, and energy is stored in the capacitor C2. The charging current i0 is suppressed by the resistor R1, and the contact K1c of the first relay coil K1 and the contact K2b of the second relay coil K2 are not switched by the charging current i0.

When the ignition sequence is normally executed when the capacitor C2 is sufficiently charged, the relay control circuit 4 outputs the relay drive signal DS. The relay drive signal DS is an ON / OFF signal, is inverted by the inverter Q1, and is supplied to the connection point between the first relay coil K1 and the second relay coil K2.

As a result, the energy stored in the capacitor C2 is discharged through the path of the capacitor C2 → diode D3 → diode D2 → first relay coil K1 → inverter Q1 and the discharge current i1 flows into the inverter Q1.

The first relay coil K1 is excited by the discharge current i1 flowing into the inverter Q1. As a result, the normally open terminal of the contact K1c is closed, AC power is supplied from the AC power supply 1 to the load 2, the valve of the electromagnetic valve is opened, and fuel is supplied to the boiler.

Further, the energy stored in the capacitor C2 is discharged within a short time, and the discharge current i0 also becomes zero.
When the normally open terminal of c is closed, this time the normally open terminal of the contact K1c → capacitor C1 → diode D2 → first relay coil K1 → inverter Q1 from AC power supply 1 to first
Since the excitation current of the relay coil K1 is supplied and the excitation of the first relay coil K1 is maintained, the normally open terminal of the contact K1c remains closed, and AC power is supplied from the AC power supply 1 to the load 2. The valve of the electromagnetic valve is opened and the state where the fuel is supplied to the boiler is maintained.

When the power supply is cut off, the AC power supply 1
Since the exciting current is not supplied to the relay coil K1,
The contact K1c returns to the original state, the AC power supplied to the load 2 is cut off, and the contact K1c stops normally.

Next, the operation when an abnormality occurs will be described.

A case where an abnormality occurs while the first relay coil K1 is excited and a case where a wire break occurs in the second relay coil K2 will be described respectively.

"When an abnormality occurs while the first relay coil K1 is excited" The operation from when the power is turned on until the excitation of the first relay coil K1 is maintained has already been described. The description is omitted.

The contact K2b is closed and the contact K2b is closed.
1c is switched so that the normally open contact is closed and the normally closed contact is open.

When an abnormality occurs, the relay control circuit 4 detects the occurrence of the abnormality and turns off the relay drive signal DS that has been output until then. As a result, contact K2b → normally open contact of contact K1c → capacitor C1 → diode D2
→ First relay coil K1 → Exciting current of the first relay coil K1 supplied from the AC power supply 1 through the path of the inverter Q1 disappears and flows into the capacitor C2 through the second relay coil K2.

By this exciting current, the second relay coil K2
Is excited and the contact K2b opens. Then, the exciting current that has excited the first relay coil K1 and the second relay coil K2 is cut off by the contact K2b, and thus becomes zero.
The excitation of the first relay coil K1 and the second relay coil K2 is released, and the contacts K1c and K2b that have been switched until then are restored to the original state. As a result, the load 2 is disconnected from the AC power supply 1.

"When the second relay coil K2 is broken"

In this case, since the second relay coil K2 is disconnected, the charging current does not flow in the capacitor C2 even when the power is turned on, and energy is not stored in the capacitor C2. Therefore, even when the relay drive signal DS is output from the relay control circuit 4, the first relay coil K1 is not excited and the load 2 is also cut off from the AC power supply.

Next, another embodiment of the relay drive circuit of the present invention will be described with reference to the drawings.

FIG. 2 is an electric circuit diagram showing the configuration of a relay drive circuit used in a combustion safety device such as a boiler. In FIG. 2, the same or corresponding parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In this relay drive circuit, the contact K2b is composed of a normally open terminal and a normally closed terminal.

Further, a thermostat contact SS is connected to the normally closed terminal of the contact K2b, and the fan motor 5 is connected via this thermostat contact SS. Opening and closing of the thermostat contact SS is controlled by a thermostat (not shown).

Further, the normally closed terminal of the contact K2b is connected to the common terminal of the contact K1c via the thermostat contact SS. The alarm circuit 6 is connected to the normally open terminal of the contact K2b. The normally open terminal of the contact K2b is the diode 11
And a first relay coil K1 via a series circuit of a resistor R11
It is connected to the.

The reset switch SW1 is connected between one end of the first relay coil K1 and the ground. The timer circuit 7 outputs the relay drive signal DS after a lapse of a fixed time after the thermostat contact SS is closed, and turns off the relay drive signal DS after the ignition trial timing.

The flame detection circuit 8 includes the first relay coil K1.
It is a circuit for holding the
The holding signal HS of the relay coil K1 is output.

Next, the operation will be described.

First, the power is turned on. When the thermostat contact SS is closed, the normally closed contact of the contact K2b → the thermostat contact SS → the normally closed terminal of the contact K1c → the diode D1 → the resistor R1 → the first relay coil K1 → the second relay coil K2 → the capacitor C2. A current i0 flows and energy is stored in the capacitor C2.

When the capacitor C2 is fully charged,
When the ignition sequence is normally executed, the timer circuit 7 outputs the relay drive signal DS. This relay drive signal D
S is inverted by the inverter Q1 and the first relay coil K1
Is supplied to the connection point of the second relay coil K2.

As a result, the energy stored in the capacitor C2 is diode D3 → diode D2 → resistor R
The discharge current i1 is discharged through the path of 12 → first relay coil K1 → inverter Q1 and flows into the inverter Q1.

The first relay coil K1 is excited by the discharge current i1 flowing into the inverter Q1, the normally open terminal of the contact K1c is closed, the ignition trial timing is entered, and the AC power is supplied from the AC power supply 1 to the load 2.
The electromagnetic valve opens and fuel is supplied to the boiler.

Thereafter, the normally closed terminal of the contact K2b → the thermostat contact SS → the normally open terminal of the contact K1c → the capacitor C
1 → resistor R3 → diode D2 → resistor R12 → first relay coil K1 → inverter Q1 the exciting current of the first relay coil K1 is supplied from the AC power supply 1, the excitation of the first relay coil K1 is maintained, The normally open terminal of the contact K1c remains closed.

Further, the timer circuit 7 causes the relay drive signal DS
If the flame detection circuit 8 outputs the flame detection signal HS after turning off, the exciting current of the first relay coil K1 flows into the inverter Q2, so that the excitation of the first relay coil K1 is maintained.

When the power supply is cut off, the AC power supply 1
Since the exciting current is not supplied to the relay coil K1,
The contact K1c returns to the original state, the AC power supplied to the load 2 is cut off, and the contact K1c stops normally.

If the timer circuit 7 turns off the relay drive signal DS after the ignition trial timing and the flame detection circuit 7 does not output the holding signal HS of the first relay coil K1 at this time, the contact K2b is normally turned on. Closed contact → thermostat contact SS → normally open contact of contact K1c → capacitor C1 → resistor R13 → diode D2 → resistor R1
2 → first relay coil K1 → excitation current flowing only in the first relay coil K1 along the path of the inverter Q1
It flows into the capacitor C2 through the relay coil K2.

At this time, since the outputs of the inverter Q1 and the inverter Q2 are both at the "H" level, the output currents of the inverters Q1 and Q2 also flow into the capacitor C2 through the second relay coil K2.

As a result, the second relay coil K2 is excited by these currents, the contact K2b is switched, the normally closed terminal of the contact K2b is opened, and the normally open terminal is closed. Therefore, contact K2b → diode D11 → resistor R11 → first relay coil K1 → second relay coil K
The current i2 flows through the route of 2 and the first relay coil K1 and the second relay coil K1.
Energize the relay coil K2.

In this state, the fan motor 5 and the load 2 do not operate because they are not connected to the AC power supply 1 by the contact K2b, while the alarm device 6 is connected to the AC power supply 1 and issues an alarm. Further, when the reset switch SW1 is closed in this state, the current i2 flows into the ground and the current i2 flowing through the first relay coil K1 and the second relay coil K2 becomes zero, so that the contact K2b and the contact K1c are the original. The state returns to the state of waiting for the output of the relay drive signal DS of the timer circuit 7, that is, the reset state.

As described above, in this embodiment, when the relay drive signal DS is applied from the timer circuit 7 after the sufficient energy is stored in the capacitor C2, the load 2 is driven by the energy stored in the capacitor C2. Therefore, the first relay coil K1 and the second relay coil K
The disconnection check of No. 2 will be automatically performed when the power is turned on, the relay coil will not operate from the beginning for disconnection, and if an abnormality occurs during operation, the AC supplied to the load 2 The power is cut off.

Further, when the flame is not detected with the relay drive signal DS turned off after the ignition trial timing, the AC power supplied to the load 2 is cut off, and at the same time, the alarm circuit is activated and an alarm is issued. .

[0077]

As described above, according to the present invention, it is not necessary to separately provide a circuit for driving a load and a circuit for driving an alarm circuit, and the relay drive signal is not a pulse signal but an ON / OFF signal. Since an off signal is sufficient, the circuit structure can be simplified and a compact structure can be accommodated in a narrow space while ensuring safety, and further, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing a configuration of an embodiment of a relay drive circuit used in a combustion safety device such as a boiler.

FIG. 2 is an electric circuit diagram showing a configuration of another embodiment of a relay drive circuit used in a combustion safety device such as a boiler.

FIG. 3 is an electric circuit diagram showing a configuration of a conventional relay drive circuit used for a combustion safety device of a boiler.

FIG. 4 is an electric circuit diagram showing a configuration of a load circuit and an alarm circuit.

[Explanation of symbols]

C2 Capacitor (energy storage means) Q1 Inverter (load drive relay trigger means, alarm relay drive means when an error occurs) K1c contact (load drive relay holding means) K2b contact (load drive relay reset means, load cutoff means) Q2 inverter (alarm) Relay drive means) SW1 Reset switch (relay reset means) 4 Relay control circuit (relay drive signal control means) 7 Timer circuit (relay drive signal control means) 8 Flame detection circuit (flame detection means)

Claims (2)

(57) [Claims] 1. An ignition sequence performed after the power is turned on is discriminated whether it is normal or abnormal, and when normal, a relay drive signal is output after a predetermined time has elapsed, and when abnormal, the relay drive signal is turned off. Energy storage means for storing energy supplied from a power source through a relay drive signal control means, a load drive relay for driving a load, and an alarm relay for generating an alarm signal or operating an alarm circuit; The load drive relay trigger means for operating the load drive relay with the energy stored by the energy storage means by using the relay drive signal as a trigger, and the load drive relay operated by the load drive relay trigger means are supplied from a power source. Load drive relay holding means to hold by the energy to A relay drive circuit comprising alarm relay drive means for driving the alarm relay, and load drive relay reset means for resetting the load drive relay held by the load drive relay holding means by driving the alarm relay. 2. An ignition sequence performed after the power is turned on is discriminated as to whether it is normal or abnormal. When the ignition sequence is normal, a relay drive signal is output after a lapse of a predetermined time, and when abnormal, the relay drive signal is turned off. Relay drive signal control means,
Power is supplied from the power supply through a flame detection means that outputs a flame detection signal when a flame is detected, a load drive relay for driving a load, and an alarm relay for generating an alarm signal or operating an alarm circuit. Energy storage means for storing energy, load drive relay trigger means for operating the load drive relay with the energy accumulated by the energy storage means triggered by the relay drive signal, and the load drive relay trigger means for operating Load drive relay holding means for holding the load drive relay by the energy supplied from the power source, and an alarm relay for driving the alarm relay when the relay drive signal is off and no flame detection signal is output from the flame detection means. The load is powered by driving the driving means and the alarm relay. Relay driving circuit comprising a load shedding unit for al blocking, a relay reset means for resetting the alarm relay which is driven by a retained load driving relay and the alarm relay driving means by the load drive relay holding means.