JPH07170653A - Power line protection device - Google Patents

Abstract

PURPOSE:To provide a protection device of a power line which does not require the replacement of a breaking member such as fuse. CONSTITUTION:In a power line protection device 10 which is inserted into a power line 3 connecting a power supply and a load 2, a heating body 11 generating heat when an eddy current flows to the power line 3, a breaking mechanism 12 for breaking the power line 3 in response to the heat of the heating body 11, and a retention mechanism 13 for retaining break state when the continuity of the power line 3 is broken and canceling the break state when a reset operation is performed are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power line protection device for protecting a power line used in an automobile or the like from a fire or melting damage.

[0002]

2. Description of the Related Art As shown in FIG. 5, an automobile power supply circuit connects a vehicle-mounted battery 1 as a power supply to a load 2 with a power supply line 3. If the power supply line 3 is short-circuited for some reason, There is a possibility that an overcurrent will flow in the wire 3 to cause ignition and smoke. Therefore, for example, as described in JP-A-62-247723,
A protective means such as a fusible link 4 and a fuse 5 is inserted on the way to protect the power supply line 3.

[0003]

By the way, the fusible link and the fuse have a fusible body for cutting off the circuit, and the fusible body is blown by the heat generated when an abnormal current flows to cut the circuit. Therefore, once it works, it must be replaced. Therefore, it is necessary to install these in a place that is easy to perform maintenance, and the installation place is limited.Fuses are concentrated in a specific place, which not only reduces space efficiency but also increases the length of wire handling. There was a problem such as becoming.

In consideration of the above circumstances, the present invention provides a power line protection device which is maintenance-free and can be installed at any place, and which can reduce the length of the electric wires to a necessary minimum. The purpose is to provide.

[0005]

According to another aspect of the present invention, there is provided a power supply line protection device, wherein a heating element generates heat when an overcurrent flows through the power supply line, and the power source is responsive to the heat of the heating element. A disconnection mechanism for disconnecting the continuity of the power line; and a holding mechanism for retaining the interrupted state once the continuity of the power supply line is interrupted and releasing the interrupted state when a reset operation is performed. .

The power line protection device according to the invention of claim 2 is characterized in that the heating element is a resistor inserted in series with the power line.

A power line protection device according to a third aspect of the present invention is characterized in that the heating element is a transistor inserted in series with the power line.

According to a fourth aspect of the present invention, there is provided a power line protection device in which the shut-off mechanism is a temperature-sensitive switch that is inserted in series with the power line and that opens a contact in response to the heat of the heating element.

The power line protection device according to a fifth aspect of the present invention is characterized in that the holding mechanism is a thyristor inserted in series with the power line.

According to a sixth aspect of the present invention, there is provided a power line protection device in which a shutoff mechanism and a holding mechanism are connected in series to a normally closed relay inserted in the power line and a drive coil of a relay connected in parallel to the power line. It is characterized in that it is composed of a connected thyristor and a temperature sensitive switch which gives a trigger signal to the gate of the thyristor by closing the contact in response to the heat of the heating element.

[0011]

In the device of the first aspect of the present invention, when an overcurrent flows in the power supply line due to a short circuit or the like, the heating element generates heat, and the heat causes the interruption mechanism to operate to interrupt the continuity of the power supply line. As a result, no current flows through the power line, and the power line is protected from fire or the like. This cutoff state is safe because it is held until the reset operation is performed by the holding mechanism. Then, after the cause of the short circuit or the like is removed, a reset operation can be performed to release the cutoff state.

In the device of the second aspect of the present invention, when an overcurrent flows through the power supply line due to a short circuit or the like, the resistance as a heating element generates heat, and the heat causes the interruption mechanism to operate.

In the device of the third aspect of the present invention, when an overcurrent flows through the power supply line due to a short circuit or the like, the transistor as the heating element generates heat, and the heat causes the cutoff mechanism to operate.

In the device of the fourth aspect of the present invention, when an overcurrent flows through the power supply line due to a short circuit or the like, the heating element generates heat, and the heat causes the contact of the temperature sensitive switch to open, thereby interrupting the continuity of the power supply line. It When the temperature of the heating element is lowered by shutting off the power supply line, the contact of the temperature sensitive switch is closed again, but regardless of this, the holding mechanism maintains the shutoff state until the reset operation of itself is performed, which is safe. Then, if the reset operation is performed after the cause of the overcurrent is removed,
The blocking state can be released.

In the device of the fifth aspect of the present invention, while the current flows through the power supply line, the self-holding function of the thyristor maintains the continuity of the power supply line. An overcurrent flows in the power supply line due to a short-circuit, etc., the heating element generates heat, and the heat shuts off the cutoff mechanism, interrupting the continuity of the power supply line, and the current stops flowing, causing the thyristor to turn off. Become. Since this state is maintained until a trigger signal (positive voltage) is input to the gate of the thyristor, even when the above-mentioned temperature sensitive switch is used for the shutoff mechanism, the shutoff state of the power supply line is maintained. That is, when using the temperature sensitive switch,
When the temperature of the heating element drops, the contacts close again to connect the power supply line, but the thyristor inserted in series with the power supply line remains in the OFF state until the trigger signal is input once it becomes OFF, The cutoff state of the power line is maintained. Therefore, it is safe. Then, after removing the cause of the overcurrent, if the trigger signal is applied to the gate of the thyristor, the thyristor can be turned on to release the cutoff state.

In the device of the sixth aspect of the present invention, in a normal state, the power supply line is held in the conductive state by the normally closed relay. At this time, the thyristor that does not apply the trigger signal to the gate is O
Since it is in the FF state, no current flows in the drive coil of the relay, and the relay contact remains closed. From this state,
When an overcurrent flows in the power supply line due to a short circuit or the like, the heating element generates heat, the heat closes the contact of the temperature sensitive switch, and a trigger signal is applied to the gate of the thyristor. Then, the thyristor is turned on, current flows through the drive coil of the relay, the contact of the relay is opened, and the continuity of the power supply line is cut off. When the power supply line is cut off, the temperature of the heating element drops and the contact of the temperature sensitive switch returns to the open position.However, once the trigger signal is applied to the gate of the thyristor and the current flows, the gate voltage becomes zero. Since the ON state is maintained by itself, the current continues to flow in the drive coil, the relay contact is maintained in the open state, and the cutoff state of the power supply line is maintained. Therefore, it is safe. Then, after removing the cause of the short circuit, etc., once the power is turned off, the thyristor is turned off, the energization of the drive coil is cut off, the relay contacts return to the closed position, and the power supply line is cut off. It will be canceled.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a protection device 10 according to a first embodiment of the present invention.
Is a circuit diagram in which is inserted in the middle of the power supply line 3. The protection device 10 includes a resistor 11 as a heating element inserted in series with the power supply line 3, a temperature-sensitive reed switch (temperature-sensitive switch) 12 as a cutoff mechanism, and a thyristor as a holding mechanism (here, "SCR" is used. 13). The temperature sensitive reed switch 12, the resistor 11, the thyristor 13,
From the positive terminal side of the battery 1 to the load 2 side,
They are arranged in this order. The thyristor 13 is the gate 13
a is connected to the ground side.

The resistor 11 is connected to the power line 3 due to a short circuit or the like.
It efficiently generates heat when an overcurrent flows through it, and is about several tens of mΩ. Temperature sensitive reed switch 12
Is a type that opens a contact in response to an increase in the temperature of the surrounding environment, and is arranged so as to be sufficiently affected by the heat generation of the resistor 11 (reference numeral 14 denotes the resistor 11 and the temperature-sensitive reed switch 12). It is in a state of "thermal bonding" like this).

FIG. 2 shows a resistor 11 and a temperature sensitive reed switch 1.
2 shows the substrate 15 on which the thyristor 13 is arranged. Board 1
5 has three terminals 15A, 15B, 15C, two of which are terminals for connecting to the power supply line 3 in series, and the rest are terminals for applying a trigger signal. On this board 15, the resistor 11 and the temperature-sensitive reed switch 12 are mounted very close to each other so that the temperature-sensitive reed switch 12 is easily affected by the heat of the resistor 11.

Next, the operation will be described.

When an overcurrent flows through the power supply line 3 due to a short circuit or the like, the resistor 11 generates heat, and the contact of the temperature-sensitive reed switch 12 is opened in response to the heat and the conduction of the power supply line 3 is cut off. When the temperature of the resistor 11 naturally radiates and drops due to the interruption of the power supply line 3, the contact of the temperature-sensitive reed switch 12 closes again, but since the thyristor 13 is inserted in the power supply line 3 in series, the continuity is once cut off. The cutoff state of the power line 3
It is held by this thyristor 13.

When the trigger signal (positive voltage) RSS as a reset operation is applied to the thyristor 13 after removing the cause of the overcurrent, the thyristor 13 is turned on and the cutoff state of the power supply line 3 is released. The trigger signal RSS may be output from a control unit such as a diagnosis, or may be output from a push switch or the like.

As described above, in order to release the cutoff state, it is only necessary to give the thyristor 13 a trigger signal. Therefore, if the signal path for giving the trigger signal is secured, the conduction state can be restored by remote control. it can. Therefore, there is no need to replace the fuse and the like, and maintenance-free operation can be achieved.

FIG. 3 shows a protection device 20 according to the second embodiment of the present invention.
3 is a circuit diagram in which is inserted into the power supply line 3 in the control unit 21. FIG. The control unit 22 is connected to the power line 3 in the control unit 21.
A drive transistor 23 that is turned on / off by a signal from is inserted, and the transistor 23 is turned on / off.
Is designed to drive the load 2. The transistor 23 is incorporated in the protection device 20 in place of the resistor 11 of the first embodiment. That is, the temperature-sensitive reed switch 1 is connected in series with the transistor 23.
2. The thyristor 13 is connected, and the protection device 20 is constituted by these, and the temperature-sensitive reed switch 12 operates in response to abnormal heat generation of the transistor 23. In this case, the control unit 22 outputs the trigger signal RSS to the thyristor 13. The operation of the second embodiment is the same as that of the first embodiment except that the transistor 23 replaces the resistor 11 as the heating element, and therefore the description thereof is omitted.

FIG. 4 shows a protection device 30 according to the third embodiment of the present invention.
Is a circuit diagram in which is inserted in the middle of the power supply line 3. This protection device 30 has a resistor 11 inserted in series with the power supply line 3 and a normally closed relay 31 in which relay contacts 31 a and 31 b are connected in series with the power supply line 3.

The drive coil 31c of the relay 31 has a power supply line 3
A thyristor 32 is arranged between the drive coil 31a and the ground. In addition, the point of the power line 3 on the front side of the relay 31 and the gate 32 of the thyristor 32.
a is connected via a temperature sensitive reed switch 33. The temperature sensitive switch 33 is of a type that closes its contacts in response to a rise in temperature of the surrounding environment, and is arranged so as to sufficiently receive the heat of the resistor 11 (reference numeral 34 denotes the resistor 11 and the temperature sensitive lead). Switch 33 is such a "thermal bond"
It shows that it is in the state of). In this embodiment, the breaking mechanism and the holding mechanism are the relay 31 and the thyristor 3.
2. The temperature sensitive reed switch 33.

Next, the operation will be described.

In the normal state, the power line 3 is held in the conductive state by the normally closed relay 31. At this time, the contact of the temperature-sensitive reed switch 33 is opened, and the trigger signal is not applied to the gate 32a, so the thyristor 33 is turned off.
In this state, no current flows through the drive coil 31c of the relay 31, and the relay contacts 31a and 31b remain closed.

From this state, the power supply line 3 is shorted or the like.
When an overcurrent flows through the resistor 11, the resistor 11 generates heat, and the heat causes the contact of the temperature-sensitive reed switch 33 to close.
The trigger signal RSS is applied to the gate 32a of the. Then, the thyristor 32 is turned on, a current flows through the drive coil 31c of the relay 31, and the contact 31 of the relay 31
The a and 31b are opened, and the continuity of the power supply line 3 is cut off.

When the power supply line 3 is cut off, the temperature of the resistor 11 is lowered by natural heat radiation and the contact of the temperature sensitive reed switch 33 is returned to the open position. However, the thyristor 32 once receives the trigger signal RSS to the gate 32a. Current flows,
Even if the voltage of the gate 32a becomes zero, the ON state is maintained by itself, so that the current continues to flow in the drive coil 31c, the contacts 31a and 31b of the relay 31 are maintained in the open state, and the cutoff state of the power supply line 3 is maintained. To be done.

Then, after removing the cause of the short circuit or the like, once the power is turned off (this is the "reset operation" in the third embodiment), no current flows in the thyristor 32, and the thyristor 32 is turned off. , The contact 3 of the relay 31 when the drive coil 31c is de-energized
1a and 31b return to the closed position, and the cutoff state of the power supply line 3 is released.

[0033]

As described above, according to the first aspect of the invention, when an overcurrent flows through the power line due to a short circuit or the like, the power cutoff mechanism automatically shuts off the power line to maintain the state. Therefore, the power supply line can be reliably protected from fire, melting damage, and the like. Also, to release the cutoff state,
Since it suffices to perform the reset operation of the holding mechanism, there is no need for the troublesome replacement of parts such as the fuse, remote operation is possible, and maintenance-free can be achieved.
Therefore, it is possible to install it at any place, and it is possible to obtain the effect that the length of the electric wire can be shortened to the minimum.

According to the invention of claim 2, in addition to the effect of claim 1, since a resistor is used as the heating element, the structure is simple and easy to realize.

According to the invention of claim 3, in addition to the effect of claim 1, since the transistor is used as the heating element, the drive transistor of the control unit or the like can be used as it is as the heating element.

According to the invention of claim 4, in addition to the effect of claim 1, a temperature-sensitive switch as a breaking mechanism is inserted in series with the power supply line, and when the heating element generates heat, the contact of the temperature-sensitive switch opens. Since the power supply line is cut off by the power supply line, the structure is simple and suitable for application to a low current power supply circuit.

According to the invention of claim 5, in addition to the effect of claim 1, since a thyristor is used as the holding mechanism, the structure is simple and easy to realize.

According to the invention of claim 6, in addition to the effect of claim 1, since the power supply line is opened and closed by the normally closed relay, it can be applied to a large current power supply circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a main part of the first embodiment of the present invention.

FIG. 3 is a circuit diagram of a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a third embodiment of the present invention.

FIG. 5 is a circuit diagram of a conventional example.

[Explanation of symbols]

 1 Battery (Power Supply) 2 Load 3 Power Supply Line 10, 20, 30 Protective Device 11 Resistance (Heating Body) 12 Temperature Reed Switch (Cutting Mechanism) 13 Thyristor (Holding Mechanism) 13a Gate RSS Trigger Signal 23 Transistor (Heating Body) 31 Normally closed relay 31c Drive coil 32 Thyristor 32a Gate 33 Temperature sensitive reed switch

Claims (6)

[Claims] 1. A power supply line protection device inserted in the middle of a power supply line connecting a power supply and a load, wherein a heating element generates heat when an overcurrent flows through the power supply line, and the heat generated by the heating element is sensed. And a holding mechanism for holding the cutoff state once the continuity of the power supply line is cut off and for canceling the cutoff state when a reset operation is performed. Power line protection device. 2. The power line protection device according to claim 1, wherein the heating element is a resistor inserted in series with the power line. 3. The power line protection device according to claim 1, wherein the heating element is a transistor inserted in series with the power line. 4. The power supply line protection according to claim 1, wherein the cutoff mechanism is a temperature-sensitive switch that is inserted in series with the power supply line and opens a contact in response to heat of the heating element. apparatus. 5. The power line protection device according to claim 1, wherein the holding mechanism is a thyristor inserted in series with the power line. 6. A normally-closed relay in which the breaking mechanism and the holding mechanism are inserted in series with a power line, a thyristor connected in series with a drive coil of the relay connected in parallel with the power line, and the heating element. The power supply line protection device according to any one of claims 1 to 3, further comprising a temperature-sensitive switch that applies a trigger signal to the gate of the thyristor by closing the contact in response to the heat of the.