JPH1118279A - Short circuit protection device for onboard electric circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide protection against short circuits between an onboard electric circuit and a body frame through simple constitution. SOLUTION: The positive-pole terminal B1 of a battery B is connected with one end L1 of a lamp L via a power line 3. One end of a first ground wire W1 is connected with the other end L2 of the lamp L, and the other end is connected with a negative-pole wire 2 connected with the negative-pole terminal B2 of the battery B at a connecting point A. One end of a second ground wire W2 is connected with the negative-pole wire 2 at the connecting point A, and the other end is connected with a body frame 4. A fuse F is placed in the second earth wire W2. If the power line 3 is short-circuited to the body frame 4, the fuse F blows out so as to interrupt the line between the connecting point A and the body frame 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short-circuit protection device for a vehicle-mounted electric circuit for protecting a circuit from being short-circuited in a vehicle-mounted electric circuit for supplying power from a vehicle battery to a load.

[0002]

2. Description of the Related Art Conventionally, in an electric circuit mounted on an automobile, as shown in FIG. 3, a negative terminal of a battery 11 is connected to a body frame 12 and a ground side of a load 13 is connected to the body frame 12. By using the body ground, the body frame 12 is diverted as a circuit constituting part of the electric circuit, thereby improving the noise resistance performance of the electric circuit.

[0003]

However, when an electric circuit is formed by using the body frame as a ground, when the electric wire constituting the electric circuit is in contact with the electric wire and the electric wire is broken due to vibration of the vehicle body. Also, when an automobile collides, the conductors of the electric wires come into contact with the body frame to short-circuit the circuit, causing a malfunction in the load function, causing the load to fail due to the fusing of the fuse, or a large current There is a possibility that the problem that the discharge of the battery progresses due to the consumption of the battery.

An object of the present invention is to solve the above-mentioned problem and to provide a short-circuit protection device for a vehicle-mounted electric circuit which can protect a short-circuit between a vehicle-mounted electric circuit and a vehicle body frame with a simple configuration.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an on-vehicle electric vehicle having a power supply line connecting a positive terminal of a battery and one end of a load, and an earth line connecting a negative terminal of the battery and the other end of the load. In the circuit, the ground line is formed by a ground wire connecting the other end of the load and the negative terminal of the battery (claim 1).

According to this configuration, since the ground line is formed of the ground wire connecting the other end of the load and the negative terminal of the battery, even if the power line comes into contact with the vehicle body frame, the ground line is connected to the electric circuit. There is no adverse effect.

Further, in the short-circuit protection device for a vehicle-mounted electric circuit according to the first aspect, a second ground wire connecting the negative terminal of the battery and the vehicle body frame, and a current flowing through the second ground wire is equal to or higher than a predetermined level. In this case, there is provided an opening means for interrupting the second ground wire (claim 2).

[0008] According to this configuration, since the negative electrode terminal of the battery is connected to the vehicle body frame, the noise resistance of the electric circuit is improved. Further, when the current flowing through the second ground wire connecting the negative terminal of the battery and the vehicle body frame exceeds a predetermined level, the second ground wire is cut off, so that the power line comes into contact with the vehicle body frame and is short-circuited. This prevents the electric circuit from being adversely affected.

Further, in the short-circuit protection device for a vehicle-mounted electric circuit according to claim 2, the opening means is provided on the second ground wire so that a current flowing through the second ground wire is higher than a predetermined level. In this case, the fuse comprises a fuse that blows.

With this configuration, when the current flowing through the second ground wire connecting the negative terminal of the battery and the vehicle body frame exceeds a predetermined level, the fuse is blown and the second ground wire is cut off. Thus, even if the power supply line comes into contact with the vehicle body frame to cause a short circuit, the electric circuit is prevented from being adversely affected.

Further, in the short-circuit protection device for a vehicle-mounted electric circuit according to claim 2, the opening means includes a detecting means for detecting a current flowing through the second ground wire, and an interposing means provided on the second ground wire. And a switch control means for opening the switch means when the detected current exceeds a predetermined level (claim 4).

According to this configuration, the current flowing in the second ground wire is detected, and when the detected current exceeds a predetermined level, the switch is opened to cut off the second ground wire. Even if the power supply line comes into contact with the vehicle body frame to cause a short circuit, adverse effects on the electric circuit are prevented.

[0013]

FIG. 1 is a circuit diagram showing a first embodiment of a vehicle-mounted electric circuit to which a short-circuit protection device for a vehicle-mounted electric circuit according to the present invention is applied. This on-vehicle electric circuit includes a battery B, a lamp (load) L, a switch 1, a fusible link FL, a fuse F, a negative wire 2,
, And a second ground wire W2.

One end of a fusible link FL is connected to the positive terminal B1 of the battery B, and the other end of the fusible link FL is connected to one end L1 of a lamp L via a power supply line 3 having a switch 1. . One end of the first ground wire W1 is connected to the other end L2 of the lamp L,
The other end is connected to a negative wire 2 connected to a negative terminal B2 of the battery B at a connection point A.

One end of the second ground wire W2 is connected to the negative wire 2 at a connection point A, the other end is connected to the vehicle body frame 4, and a fuse F is provided on the second ground wire W2. ing.

The switch 1 is a switch for turning on and off the lamp L. The fusible link FL cuts off when an abnormality such as a short circuit occurs when the power supply line 3 comes into contact with the first ground wire W1 to cut off the power supply from the battery B to protect the circuit. belongs to.

The fuse F is cut off when an abnormality such as a short circuit of the positive terminal B1 of the battery B to the power supply line 3 to the vehicle body frame 4 occurs, thereby cutting off the connection point A to the vehicle body frame 4. belongs to.

The operation in this configuration will be described.
In a normal state, the vehicle body frame 4 is connected to the second ground wire W2.
, And the vehicle body frame 4 forms a part of a vehicle-mounted electric circuit.

On the other hand, when the power supply line 3 and the vehicle body frame 4 are short-circuited due to a break in the electric wire coating due to the vibration of the vehicle body, a collision of the vehicle, or the like, the current flowing through the second ground wire W2 increases. Fuse F blows,
The first ground wire W1 and the vehicle body frame 4 are cut off.

As described above, according to the first embodiment, the first ground wire W1 for connecting the other end L2 of the lamp L to the negative terminal B2 of the battery B is provided, and the negative terminal B2 of the battery B is connected to the vehicle body. Second connecting frame 4
, The noise resistance of the vehicle-mounted electric circuit can be improved.

A fuse F is connected to the second ground wire W2.
In this case, when the power supply line 3 and the vehicle body frame 4 are short-circuited, it is possible to cut off the connection between the vehicle body frame 4 and the first ground wire W1.
It is possible to prevent the adverse effect of the short circuit from being exerted on the vehicle-mounted electric circuit without interrupting the power supply to the lamp L.

Further, since the short circuit between the power supply line 3 and the vehicle body frame 4 can be determined based on the current flowing through the second ground wire W2, the configuration of the vehicle-mounted electric circuit can be simplified.

As shown in FIG. 1, a warning lamp WL may be connected in parallel with the fuse F, and the warning lamp WL may be arranged on the instrument panel of the vehicle. According to this configuration, when the fuse F is blown, a current flows through the warning lamp WL. Therefore, with a simple configuration, the power line 3 and the vehicle body frame 4
To the vehicle occupant.

FIG. 2 is a circuit diagram showing a second embodiment of a vehicle-mounted electric circuit to which the short-circuit protection device for a vehicle-mounted electric circuit according to the present invention is applied. The vehicle-mounted electric circuit according to the second embodiment includes an electromagnetic relay 5, a current detection resistor R, a switch 6, and a control unit 7 instead of the fuse F according to the first embodiment.

The electromagnetic relay 5 has an exciting coil 51 and a normally closed relay contact 52. The second ground wire W2 is
It has a series circuit consisting of a current detection resistor R and a relay contact 52. One end of the exciting coil 51 is connected to the power supply line 3 between the fusible link FL and the switch 1,
The other end is connected to the second ground wire W2 via the switch 6.

The control section 7 detects the voltage across the current detection resistor R, and when the detected voltage exceeds a predetermined level, determines that a short circuit has occurred between the power supply line 3 and the vehicle body frame 4 and switches 6 is turned on.

The operation in this configuration will be described.
In the normal state, since the relay contact 52 is conducting, the vehicle body frame 4 is connected to the first ground wire W1 via the second ground wire W2 as in the first embodiment.

On the other hand, when the power supply line 3 and the vehicle body frame 4 are short-circuited due to a break in the covering of the electric wire due to the vibration of the vehicle body, a collision of the vehicle, or the like, the current flowing through the current detecting resistor R increases. When the voltage across the current detection resistor R exceeds a predetermined level, the switch 6 is turned on, and the first ground wire W1 and the vehicle body frame 4 are cut off, as in the first embodiment.

As described above, according to the second embodiment, the first
By providing the electromagnetic relay 5, the current detection resistor R, the switch 6, and the control unit 7 instead of the fuse F of the embodiment, the same effects as those of the first embodiment can be obtained.

In the second embodiment, in place of the electromagnetic relay 5, a MOS-FET, IGBT (Insulate
d Gate Bipolar mode Transistor) Other semiconductor switching elements may be used.

[0031]

As described above, according to the present invention,
The ground line is made up of a ground wire that connects the other end of the load and the negative terminal of the battery, so that even if the power line contacts the vehicle body frame, it is possible to prevent the electric circuit from being adversely affected. it can.

Also, a second ground wire for connecting the negative electrode terminal of the battery and the vehicle body frame is provided, and when the current flowing through the second ground wire exceeds a predetermined level, the second ground wire is cut off. Even if the power supply line contacts the vehicle body frame to cause a short circuit, it is possible to prevent the electric circuit from being adversely affected without interrupting the power supply to the load.

Further, by providing a fuse on the second grounding wire that blows when the current flowing through the second grounding wire becomes a predetermined level or more, even if the power supply line comes into contact with the vehicle body frame and a short circuit occurs. Therefore, it is possible to prevent the electric circuit from being adversely affected without interrupting the power supply to the load.

Further, by detecting a current flowing through the second ground wire, and opening the normally closed switch means provided on the second ground wire when the detected current exceeds a predetermined level, a power supply is provided. Even if the line comes into contact with the body frame and a short circuit occurs, without interrupting the power supply to the load,
An adverse effect on the electric circuit can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a vehicle-mounted electric circuit to which a short-circuit protection device for a vehicle-mounted electric circuit according to the present invention is applied.

FIG. 2 is a circuit diagram showing a second embodiment of a vehicle-mounted electric circuit to which the short-circuit protection device for a vehicle-mounted electric circuit according to the present invention is applied.

FIG. 3 is a circuit diagram showing a conventional vehicle-mounted electric circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Switch 2 Negative wire 3 Power line 4 Body frame 5 Electromagnetic relay 51 Excitation coil 52 Relay contact 6 Switch 7 Control part B Battery B1 Positive terminal B2 Negative terminal L Lamp (load) L1 One end L2 Other end F Fuse W1 First ground Wire W2 Second ground wire

Continuation of front page (72) Inventor Hiroshi Sudo 1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi Harness Research Institute, Ltd.

Claims (4)

[Claims] 1. An in-vehicle electric circuit comprising: a power supply line connecting a positive terminal of a battery and one end of a load; and an earth line connecting a negative terminal of the battery and the other end of the load. A short-circuit protection device for a vehicle-mounted electric circuit, comprising a ground wire connecting the other end of the load and a negative terminal of the battery. 2. A short-circuit protection device for an in-vehicle electric circuit according to claim 1, wherein a second ground wire connecting the negative terminal of the battery and the vehicle body frame, and a current flowing through the second ground wire is equal to or higher than a predetermined level. A short-circuit protection device for an in-vehicle electric circuit, characterized by comprising an opening means for interrupting the second ground wire. 3. The short-circuit protection device for an in-vehicle electric circuit according to claim 2, wherein the opening means is provided on the second ground wire, and a current flowing through the second ground wire is higher than a predetermined level. A short-circuit protection device for an in-vehicle electric circuit, wherein the short-circuit protection device comprises a fuse that blows when the fuse is blown. 4. The short-circuit protection device for an in-vehicle electric circuit according to claim 2, wherein said opening means includes a detecting means for detecting a current flowing through said second ground wire, and an interposing means provided on said second ground wire. A short-circuit protection device for an in-vehicle electric circuit, comprising: a normally closed switch means; and an open control means for opening the switch means when a detected current exceeds a predetermined level.