JPH09149541A - Relay with circuit breaker function incorporated - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to add overcurrent interruption to ordinary relay operation without any additional overcurrent interrupting circuit and dispense with the replacement of parts by adding to the contact circuit of a relay a bimetal containing a movable contact spring as a self-resettable temperature detecting current interrupting element. SOLUTION: When a switch is turned on, a current is passed through the coil of a relay with a circuit breaker function incorporated, and a movable contract 1 supported on a movable contract spring 2' is brought into contact with a fixed contact 7, which allows the current to be passed through a motor (load). If a current exceeding a specified value is passed through the load, the temperature of the movable contact spring 2' is increased to a specified value or higher due to Joule heat. The movable contact spring 2' is made of bimetal; therefore, the movable contact 1 is moved away from the fixed contact 7, and the relay contact is turned off. Thus overcurrent is interrupted. It is more advantageous to provide the bimetal with an adjusting screw 8 so that the pressing force of the contract will be variable and the operating temperature at which the contact is opened will be adjustable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relay having a built-in current interruption function capable of interrupting a circuit in response to an overcurrent and also capable of interrupting an abnormal rise in ambient temperature. The present invention relates to a circuit breaker function built-in relay that is most suitable for use in a vehicle power supply circuit that uses a large current.

[0002]

2. Description of the Related Art A fuse has been used for a long time as a means for detecting heat generation due to overcurrent and breaking a circuit. However, although a circuit breaker that uses a fuse is inexpensive, it is necessary to replace the fuse to restore the circuit. Therefore, it is necessary to always prepare a fuse of the same standard, and it is necessary to replace the fuse. .

On the other hand, as an overcurrent interrupting device which does not require replacement of parts at the time of restoration operation, a device which electromagnetically detects an overcurrent to mechanically interrupt the circuit, or an electronic circuit detects an electric current to disconnect the circuit. There is something to block. However, they are expensive because they require special mechanical constructions and complex electronic circuits.

For example, the one shown in FIG. 4 is an example of a high power load circuit for a vehicle, in which the power from the + B power source is relayed (1
The electric power is supplied to the load such as the motor (12) via the circuit breaker (11) to protect the circuit.
Therefore, the system and the circuit are complicated, the number of parts is increased, the voltage is decreased due to the increase of the line length, and the cost is increased.

As another conventional example, a thermostat is used instead of a fuse in an electric circuit to automatically cut off and protect the circuit when an increase in current in the electric circuit or other abnormal state occurs. (Japanese Patent Laid-Open No. 4-280020) or, as shown in FIG. 5, between electrodes of a socket in which switches (SW1, SW2) including a bimetal are heated from an on-vehicle battery (26) when heat is generated by an overcurrent ( 8c, 9c, 10b and 8a, 9a, 10a) to form a short circuit, and the current monitoring circuit (22) detects the current increased by the formation of the short circuit by the potential across the shunt resistor (17) to conduct the current. For shutting off
208645). However, in these devices as well, it is necessary to provide an element for detecting an overcurrent in the circuit and perform wiring, and it is inevitable that the circuit is complicated and the number of parts is increased.

[0006]

As described above, in the conventional overcurrent interruption device, it is necessary to prepare and replace the replacement part, and the cost is increased due to the complicated circuit and the increase in the number of parts. There was a point.

[0007]

As a means for solving the above problems, according to the present invention, a temperature detection type current interruption element capable of self-restoration is added to a contact circuit of a relay. With this configuration, in addition to the normal relay operation, overcurrent interruption can be performed without providing a new overcurrent interruption circuit, and it is possible to obtain the one which does not require replacement of parts.

Further, as a temperature detection type current interruption element capable of self-restoration, according to the circuit breaker function built-in relay in which the movable contact spring is made of bimetal so that the contact is deformed in the direction of opening when the temperature rises. The circuit can be accurately cut off at the predetermined temperature or the predetermined current value, and the current cutoff temperature or the cutoff current can be set by the operating point adjusting member.

Further, if a relay with a circuit breaker function having a PTC element in the contact circuit inside the relay is used as the temperature detection type current interruption element capable of self-recovery, the interruption is not due to a mechanical contact. No arc is generated due to current interruption, and there is no concern about contact deterioration.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a first embodiment of the present invention, which is a temperature detection type current interruption element capable of self-recovering.
A bimetal is used for the movable contact spring of the relay. (1) shows the movable contact of the relay, (2 ') shows the movable contact spring made of bimetal, and (3) shows the bobbin around which the relay coil is wound. , (4) and (5) indicate terminals of the relay coil. Further, (7) is a fixed contact, and (6) is a power supply side terminal of the fixed contact.

A circuit using a relay having such a configuration is shown in FIG. The operation is as follows. When the switch (13) is turned on, a current flows through the coil of the relay (10) with a built-in circuit breaker function, and the movable contact (1) supported by the movable contact spring (2 ') contacts the fixed contact (7). Current flows through the motor (load) (12).

If, for some reason, a current more than a predetermined value flows through the load (12), the movable contact spring (2) becomes a temperature more than a predetermined value due to Joule heat. Since the movable contact spring (2 ') is made of bimetal, the movable contact moves in the direction away from the fixed contact (7) and the relay contact is turned off, so that the overcurrent is cut off. Further, even if the current is less than the predetermined current, the circuit is shut off when abnormal heat is generated. Therefore, by using the relay of the present invention, it is possible to obtain the same or more effective effects as those provided with the overcurrent interruption device.

The bimetal is provided with an adjusting screw 8 as shown in the figure, and the operating temperature at which the contact is opened can be adjusted by varying the pressing force of the contact. It is advantageous to leave it.

FIG. 2 shows a second embodiment of the present invention, in which a PTC is used as a temperature detection type current interruption element capable of self-recovery
(9) is used as a circuit element on the power supply side of the fixed contact of the relay. As in FIG. 1, (1) is the movable contact of the relay, (2) is the movable contact spring, and (3) is the relay contact. Coil bobbins, (4) and (5) are relay coil terminals, (6) is a power supply side terminal, and (7) is a fixed contact. Then, by using the PTC shown in (9) in the circuit from the power source side terminal (6) to the fixed contact (7) of the relay, the movable contact (1) and the fixed contact (7) come into contact with each other. When the relay contact circuit is on and a current exceeding the specified level flows, the power supply side terminal (6)
→ Fixed contact (7) → Movable contact (1) → PTC (9) provided between the power supply side terminal (6) and fixed contact (7) due to Joule heat generated in the current circuit of the movable contact spring (2) The resistance value of becomes large and shuts off the current flowing in the circuit.
The current is cut off even if abnormal heat is generated due to other causes.

FIG. 3 shows an example of a system configuration of a relay having a circuit breaker function according to the present invention. Since the current cut-off element is incorporated in the relay as described above, it is different from that shown in FIG. As compared with FIG. 3, it can be understood from FIG. 3 that a circuit breaker does not need to be additionally provided in the circuit, so that the circuit is simple and the number of wirings is reduced, so that the cost can be reduced.

[0016]

As described above, according to the present invention, since an element having an overcurrent interruption function that does not require component replacement is included inside the relay, component replacement is required for restoration as in the conventional case. There is no need to do so, there is no need to newly provide an overcurrent interruption circuit, circuit simplification and cost reduction, and overcurrent is prevented from flowing through the contact, so there is no burn-in of the relay contact. The relay is protected because the current is cut off even when the temperature is abnormal.

[Brief description of the drawings]

FIG. 1 is a perspective view of a circuit breaker function built-in relay using a bimetal for a movable contact spring according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a circuit breaker function built-in relay using a PTC according to a second embodiment of the present invention.

FIG. 3 is an example of a power supply circuit using the circuit breaker function built-in relay of the present invention.

FIG. 4 is an example of a power supply circuit using a conventional overcurrent interruption device and a relay.

FIG. 5 shows an example of a conventional overcurrent interruption device.

[Explanation of symbols]

 1 movable contact 2 movable contact spring 2'bimetal movable contact spring 3 bobbin 4 coil terminal 5 coil terminal 6 power supply side terminal 7 fixed contact 8 operating point adjusting member 9 PTC 10 relay 11 circuit breaker 12 motor (load) 13 switch 14 circuit Relay with built-in breaker function

Claims (5)

[Claims] 1. A relay with a built-in circuit breaker, wherein a temperature detection type current interruption element capable of self-restoration is added to a contact circuit of the relay. 2. The circuit breaker function built-in relay according to claim 1, wherein the current interruption element is a bimetal having a movable contact spring configured to be deformed in a direction in which the contact opens due to a temperature rise. The featured circuit breaker function built-in relay. 3. The circuit breaker function built-in relay according to claim 2, wherein the bimetal has an adjusting screw for adjusting an operating temperature at which a contact opens. 4. The circuit breaker function built-in relay according to claim 1, wherein the current interruption element is a PTC element provided in a contact circuit inside the relay. 5. The circuit breaker function built-in relay according to claim 4, wherein the PTC element is configured to change its resistance value so as to disconnect the circuit due to heat generation when the current flowing through the element is a predetermined value or more. It is a relay with a built-in circuit breaker feature.