JPS6350933B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an opening/closing control circuit for a load power supply line that protects the load by urgently shutting off the power supply line in a situation such as abnormal overheating of a load such as a hot water supply circuit of a combustion device. It is related to.

Conventionally, to protect combustion equipment from abnormal overheating, a temperature fuse or a manually-reset normally closed thermoswitch is inserted in the power supply line connected between the power source and the combustion equipment. A simple and safe protection circuit configuration was adopted in which the power supply for combustion was stopped by these cut-off operations.

However, in such a circuit configuration, it is customary to install the temperature fuse or manual reset type thermoswitch inside the appliance so that it cannot be touched except when necessary. Maintenance work such as pressing to reset the thermoswitch is time-consuming.
From a maintenance standpoint, it has the disadvantage of being inconvenient to use.

Therefore, it is an object of the present invention to simplify maintenance work without the need for troublesome operations such as replacing temperature fuses installed in the appliance or pressing manual reset buttons located inside the appliance. It is an object of the present invention to provide a load power supply circuit opening/closing control circuit that can perform the following operations.

A first embodiment of this invention is shown in FIG. That is, this load power supply line opening/closing control circuit 1 is an opening/closing control circuit for a power supply line that connects a combustion control circuit 2 of a combustion device including a burner load or a relay for controlling the burner load and a power supply 3. An operation switch 4 is connected to the power supply line and is driven on and off by manual operation to open and close the power supply line, and an operation switch 4 is connected in the middle of the power supply line closer to the power supply side than the operation switch 4 and detects abnormal overheating of the combustion device. The automatic reset type normally closed switch 5 is an example of an automatic reset type normally closed thermoswitch that shuts off the power supply path when A keep relay 6 that is connected opens the power supply path by inputting a set signal and closes the power supply path by inputting a reset signal, and inputs a set signal to the keep relay 6 in response to the off operation of the automatic return type normally closed switch 5. A keep relay reset control circuit sets the keep relay 6 so that the contact 6b is turned off, and a reset signal is input to the keep relay 6 in response to the off operation of the operation switch 4, so that the contact 6b is turned on. A keep relay reset control circuit for resetting the keep relay 6 as shown in FIG.
By maintaining the OFF state of b, the power supply path is maintained in the cutoff state even after the automatic return type normally closed switch 5 returns, preventing the combustion control circuit 2 from restarting, and the keep relay is turned off only after the operation switch 4 turns OFF. The contact point 6b of No. 6 can be reset.

The keep reset control circuit inputs a set signal to the keep relay 6 in response to the off operation of the automatic reset type normally closed switch 5, and includes transistors 7 and 8, a capacitor 9 connected in series with the keep relay 6, and the like. The transistor 7 is for operating the keep relay 6 to the set state when the automatic return type normally closed switch 5 is turned off, and the transistor 8 is for operating the keep relay 6 to the set state when the automatic return type normally closed switch 5 is turned off.
This is to prevent the transistor 7 from being turned on when the transistor 7 is in the recovery state. Bias for transistor 7 is provided by resistors R ₁ , R ₂ , and R ₃ , and bias for transistor 8 is provided by resistors R ₄ and R ₅ .

The keep relay reset control circuit that inputs a reset signal to the keep relay 6 in response to the off operation of the operation switch 4 includes transistors 10 and 1.
1, 12, etc., the transistor 10 allows the charging current to pass through the capacitor 9 to reset and drive the keep relay 6, and the transistor 11
The transistor 10 is turned on only when the automatic reset type normally closed switch 5 is in the reset state and the operation switch 4 is turned off in a reset operation, and the transistor 12 is turned on when the operation switch 4 is turned on. 10 and 11, that is, to prevent the return signal from entering the keep relay 6, and the capacitor 13
is for preventing the return of the keep relay to prevent the transistor 11 from being turned on earlier than the transistor 12 when the automatic return type normally closed switch 5 returns.
The bias of the transistor 10 is resistors R ₆ and R ₇ ,
The bias of transistor 11 is resistors R ₈ , R ₉ , R ₁₀
The bias of transistor 12 is resistor R ₁₁ ,
R ₁₂ each.

The diode 14 is used to prevent the capacitor 9 from discharging when the automatic reset type normally closed switch 5 is turned off, the resistor _R13 is used to limit the reset current, and the diode 15 is used when the operation switch 4 is turned off and the automatic reset type normally closed switch is turned off. During the off operation of 5, the diode 1
Similarly to 4, the resistor _R14 is used to prevent the capacitor 9 from discharging, and is used to limit the current in the charging path to replenish the discharged charge due to the leakage current of the capacitor 9 during operation.

The opening/closing control circuit for this load power supply path operates as follows.

When the operation switch 4 is turned on in the normal case, that is, when the automatic reset type normally closed switch 5 is in the reset state and the contact 6b of the keep relay 6 is also in the reset state, the combustion control circuit section 2 and the power source 3 are connected and the combustion operation starts. However, due to the on operation of transistors 8 and 12, transistor 7 and transistor 1 are turned on, respectively.
Keep relay 6 because 1 and 10 are off
is in an inoperative (reset) state, but the capacitor 9 is always kept charged through the resistor _R14 and the diode 15.

Next, when the automatic return type normally closed switch 5 turns off due to abnormal overheating during operation, the combustion control circuit 2
is cut off from the power supply 3, transistor 8 is turned off, and transistor 7 is turned on, so that the charge accumulated in the capacitor 9 is transferred to the keep relay 6.
This discharge current operates the keep relay 6, and the contact 6b of the keep relay 6 is magnetically held in the OFF operating state, and the automatic return type normally closed switch 5 automatically returns while the operation switch 4 remains on. However, the combustion control circuit 2 is kept cut off from the power supply 3 by the contact 6b of the keep relay 6, so that it does not restart.

The return or reset of the keep relay 6 is achieved by turning off the operation switch 4. At this time, the transistor 12 is turned off, so the transistor 11 is turned on, and the transistor 10 is turned on, and the resistor R ₁₃ , the diode 14 and the keep relay 6 are turned off. A charging current flows into the capacitor 9 through the capacitor 6, and the keep relay 6 is reset by this charging current.

With this configuration, the automatic reset type normally closed switch 5 is used as a switch that turns off when abnormal overheating is detected, making it easier to perform maintenance than in the conventional case using a temperature fuse or manual reset type thermoswitch. This eliminates the troublesome work of replacing the temperature fuse installed in the device or pressing the manual reset button, and the addition of a keep relay 6 allows the device to be restarted only by turning off the operation switch 4. By providing this function, it is possible to avoid the risk of automatic restart accompanying the return operation in the case of an automatic return type normally closed switch, and it is also possible to improve safety. Note that even if the operation switch 4 is turned on or off when the automatic return type normally closed switch 5 is activated, the contact 6b of the keep relay 6
doesn't work. Therefore, safety can be further improved.

A second embodiment of the invention is shown in FIG. That is, this opening/closing control circuit for the load power supply path is an example of controlling the power supply to a load in which a starting circuit 16 such as another thermo circuit for starting the combustion control circuit 2 is connected to the combustion control circuit 2. Starting circuit 1
6 and contact 6 of keep relay 6 of opening/closing control circuit 1
b, and even if the automatic return type normally closed switch 5 of the opening/closing control circuit 1 once turns off and then automatically returns, the starting circuit 16 is controlled by keeping the contact 6b of the keep relay 6 in the off state. The transistor 17 is designed to prevent restarting, and the transistor 17 is for driving the starting relay 18. 1
8a is a contact point of the starting relay 18. Other than that, the configuration and operation of the opening/closing control circuit 1 are the same as those in the first embodiment.

With this configuration, even when power is supplied to a load having a separate starting circuit 16 such as a thermo circuit, restarting after the automatic reset normally closed switch 5 returns is reliably avoided, as in the first embodiment. be able to.

A third embodiment of the invention is shown in FIG. In other words, this load power supply line opening/closing control circuit is an example applied when the combustion control circuit 2 is equipped with a safety circuit 19 that detects situations such as a false flame, misfire, or non-ignition and outputs an abnormality detection signal. In addition to the input of the set signal accompanying the off operation of the automatic return type normally closed switch 5 to the keep relay 6 of the opening/closing control circuit 1, the abnormality detection signal of the safety circuit 19 is input to the keep relay 6. Set drive is performed, and power supply to the combustion limiting circuit 2 is stopped by turning off the contact 6b of the keep relay 6, and another alarm circuit 20 consisting of a buzzer or the like is connected to the operating side of the contact 6a of the keep relay 6. Then, the automatic return type normally closed switch 5 turns off, detects an abnormality, and notifies the alarm circuit 20 that the switch has automatically returned. Reference numeral 21 denotes a driving transistor that inputs a set signal to the keep relay 6 to operate it when the safety circuit 19 is operated. others,
The configuration and operation of the opening/closing control circuit 1 are as described in the first
This is similar to the embodiment.

With this configuration, the keep relay 6 of the opening/closing control circuit 1 can also be used as a driving relay for the alarm circuit 20 based on the abnormality detection signal of the safety circuit 19, and the circuit configuration can be simplified.

As described above, the load power supply path opening/closing control circuit of the present invention includes an operation switch that opens and closes the power supply path to the load, and a circuit that is connected in the middle of the power supply path closer to the power supply side than the operation switch to detect abnormalities in the load. An automatic reset type normally closed switch that shuts off the power supply line when the switch is turned off, and a contact of its own that is connected in the middle of the power supply line closer to the load side than the operation switch, opens the power supply line when a set signal is input, and closes the power supply line when a reset signal is input. a keep relay that closes the switch, and a keep relay reset control circuit that inputs a set signal to the keep relay in response to the off operation of the automatic return type normally closed switch and sets the keep relay so that the contact turns off;
and a keep relay reset control circuit for resetting a keep relay so that a contact is reset in response to an OFF operation of the operation switch when the automatic return type normally closed switch is in a closed state, the automatic return type normally closed switch By keeping the contacts of the keep relay in the OFF state with the OFF operation of the operation switch, the power supply path is maintained in the cut-off state even after the automatic return type normally closed switch returns, thereby preventing the load from restarting. Since the keep relay contacts are designed to return, the restart during automatic return operation, which is a disadvantage of automatic return type normally closed switches, can be avoided by adding the keep relay, and automatic return type normally closed switches can be used. A reset function can be added that allows restarting by turning off the operation switch using a normally closed switch, and can be restarted by replacing the temperature fuse installed in the equipment or by pressing a manual reset button. This has the advantage that troublesome work for maintenance can be omitted and maintenance can be performed easily. Furthermore, with the above configuration, the power supply path to the load can be reliably interrupted in the event of an abnormality at two locations: the automatically reset type normally closed switch and the contact point of the keep relay. Furthermore, even if the operation switch is opened or closed while the automatic reset type normally closed switch is open (in the event of an abnormality), the keep relay contacts will remain open, so the power supply to the load can be cut off reliably. Safety can be improved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the invention, FIG. 2 is a schematic circuit diagram showing a second embodiment, and FIG. 3 is a schematic circuit diagram showing a third embodiment. . 1...Opening/closing control circuit, 2...Combustion control circuit (load), 3...Power source, 4...Operation switch, 5...
Automatic return type normally closed switch, 6...Keep relay,
6b... Contact, 7, 8, 10, 11, 12, 1
7, 21... Transistor, 9, 13... Capacitor, 14, 15... Diode, 16... Starting circuit, 18... Starting relay, 18a... Contact,
19...safety circuit, 20...alarm circuit.

Claims (1)

[Claims] 1. An operation switch that opens and closes a power supply path to a load;
An automatic reset type normally closed switch is connected in the middle of the power supply path closer to the power supply side than the operation switch, and detects an abnormality in the load and shuts off the power supply path. A keep relay to which the contacts of the switch are connected opens the power supply path upon input of a set signal and closes the power supply path upon input of a reset signal, and a set signal is input to the keep relay in response to the off operation of the automatic reset type normally closed switch. A keep relay reset control circuit that sets the keep relay so that the contact turns off; and a keep relay reset control circuit that inputs a reset signal to the keep relay in response to the off operation of the operation switch when the automatic return type normally closed switch is in the closed state. and a keep relay reset control circuit that resets the keep relay so that the contact returns to its original state, and maintains the contact of the keep relay in the OFF state when the automatic return type normally closed switch is turned off, thereby causing the automatic return type normally closed switch to operate. The opening/closing control circuit for the load power supply path maintains the power supply path cutoff state even after the return operation to prevent restarting of the load, and restores the contact point of the keep relay by turning off the operation switch. 2. The load according to claim 1, wherein the load includes a starting circuit that controls its own starting, and the keep relay is configured to turn off the starting circuit by turning off its own contacts. Opening/closing control circuit for load power supply path. 3. The keep relay is maintained in a set state in which the contact is turned off even by an output signal of an abnormality detection circuit other than the automatic return type normally closed switch,
2. The opening/closing control circuit for a load power supply path according to claim 1, wherein an alarm circuit is driven in accordance with the set state.