JP2015033161A - On-vehicle apparatus and vehicle fuse melting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle apparatus and vehicle fuse melting method, capable of timely protecting an internal circuit even when an overcurrent occurs to such a degree that a vehicle fuse does not melt.SOLUTION: In any of on-vehicle apparatuses 3-1 to 3-N connected with a battery power line 1a, when an overcurrent of the battery power line 1a is detected and any on-vehicle apparatus which has detected an overcurrent makes notification of the detection, control circuits 5-1 to 5-N operate a load circuit owned by each of the on-vehicle apparatuses to melt a vehicle fuse 2 by flowing an electric current of the load circuit owned by the self-apparatus together with an electric current of a load circuit of any other on-vehicle apparatus which has detected an overcurrent.

Description

  The present invention relates to an in-vehicle device having a function of detecting an overcurrent in a battery power line of a vehicle and protecting an internal circuit, and a vehicle fuse blowing method.

Conventionally, when an overcurrent is detected in an electronic device, the failure point is isolated from another circuit by cutting off from another circuit or by blowing a fuse.
For example, in Patent Document 1, a fuse that blows when an abnormal current flows in the middle of a wiring that supplies electric power to an electric load of a vehicle, and the fuse is arranged in series with the fuse so that the abnormal current flows. A protection device for a vehicle wiring system is disclosed that includes a PTC element that increases a resistance value to reduce a current before a fuse is blown.

JP 2001-327068 A

Vehicles installed on the battery power line of the vehicle when the control circuit that shuts down the failure circuit has failed due to factors such as foreign matter entering the in-vehicle equipment and the internal circuit has a short circuit (partial short circuit) Although not so great as to blow the fuse, an overcurrent larger than usual may flow. In this case, since the circuit is not interrupted and the vehicle fuse is not melted, the overcurrent continues to flow for a long time, and the in-vehicle device may ignite and smoke.
Such a problem cannot be dealt with by the conventional technique represented by Patent Document 1, and the internal circuit of the in-vehicle device cannot be protected accurately.

  The present invention has been made to solve the above-described problems, and is capable of accurately protecting an internal circuit and a vehicle fuse fusing method capable of accurately protecting an internal circuit even when an overcurrent is generated to such an extent that the vehicle fuse does not melt. The purpose is to obtain.

  The vehicle-mounted device according to the present invention is a vehicle-mounted device that has a function of protecting an internal circuit from an overcurrent generated in a battery power supply line that supplies power from a vehicle-mounted battery and is connected to one or more battery power supply lines. The overcurrent detection circuit that detects the overcurrent generated in the battery power supply line, the load circuit for flowing current through the battery power supply line, and the load circuit operates when an overcurrent is detected by the overcurrent detection circuit And a control circuit for increasing the current of the battery power supply line and fusing the vehicle fuse provided in the battery power supply line.

  According to the present invention, there is an effect that the internal circuit can be protected accurately even if an overcurrent is generated to such an extent that the vehicle fuse does not melt.

It is a block diagram which shows the structure of the vehicle-mounted system using the vehicle-mounted apparatus which concerns on Embodiment 1 of this invention. 3 is a flowchart showing a vehicle fuse fusing method according to the first embodiment.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of an in-vehicle system using an in-vehicle device according to Embodiment 1 of the present invention, and shows a system in which N in-vehicle devices are connected to a battery power line 1a. In FIG. 1, when an internal circuit (not shown) of the in-vehicle devices 3-1 to 3 -N is completely short-circuited (dead short), the vehicle fuse 2 is blown by a large current flowing through the battery power supply line 1 a.
However, when a so-called rare short circuit that has a short-circuit resistance to a certain extent and that is incompletely short-circuited occurs, an overcurrent larger than usual flows to the battery power supply line 1a, although not so much as to blow the vehicle fuse 2. . If this state of overcurrent continues for a long time, the location where the rare short-circuit has occurred locally generates heat and accumulates heat, which may cause the vehicle-mounted device to smoke or ignite.

  Therefore, the vehicle-mounted device according to the present invention blows the vehicle fuse 2 by actively passing a current through the battery power line 1a when an overcurrent due to a short circuit is detected in the battery power line 1a. As a result, the internal circuit can be accurately protected even if an overcurrent that does not blow the vehicle fuse 2 occurs.

In the in-vehicle system shown in FIG. 1, a vehicle fuse 2 is disposed in a battery power line 1 a that supplies electric power from the in-vehicle battery 1 to the in-vehicle devices 3-1 to 3 -N. The battery power supply line 1a is connected to the internal circuit of the in-vehicle devices 3-1 to 3 -N, and the in-vehicle devices 3-1 to 3 -N operate with power supplied from the battery 1.
The vehicle fuse 2 is blown by a large current flowing in the battery power supply line 1a due to a complete short circuit occurring in any of the internal circuits of the in-vehicle devices 3-1 to 3-N.
The in-vehicle devices 3-1 to 3-N are in-vehicle devices having a function of protecting the internal circuit from an overcurrent generated in the battery power supply line 1a. The overcurrent detection circuits 4-1 to 4-N and the control circuit 5 -1 to 5-N and load circuits 6-1 to 6-N.

The overcurrent detection circuits 4-1 to 4-N are overcurrent detection circuits that detect an overcurrent generated in the battery power supply line 1a. Here, the overcurrent detected by the overcurrent detection circuits 4-1 to 4-N is assumed to be a current that flows to the battery power supply line 1a due to a rare short circuit of the internal circuit, and the battery power supply line 1a due to a complete short circuit of the internal circuit. The current value is lower than the current value flowing through the current, but larger than the current value allowed in normal operation.
The detection of the overcurrent caused by the rare short may be determined, for example, by comparing the detected current with a preset current threshold value. However, an overcurrent that does not exceed a preset threshold value may also occur depending on a rare short state.
Therefore, even if an abnormal current (overcurrent) in the battery power supply line 1a is detected by measuring a change amount of the current flowing through the battery power supply line 1a per predetermined time and comparing the change amount with a predetermined threshold value. Good.

The control circuits 5-1 to 5-N are realized by microcomputers mounted on the in-vehicle devices 3-1 to 3-N, and when the overcurrent is detected by the overcurrent detection circuits 4-1 to 4-N, This is a control circuit that operates the load circuits 6-1 to 6-N to actively flow a current through the battery power supply line 1a to blow the vehicle fuse 2 disposed in the battery power supply line 1a.
The control circuits 5-1 to 5 -N are connected to each other for communication with an in-vehicle LAN (Local Area Network) 7. When an overcurrent is detected by the overcurrent detection circuit of its own device, the control circuit notifies the control circuit of another in-vehicle device of this overcurrent detection via the in-vehicle LAN 7.
Further, the control circuit 5-1 is connected to the overcurrent detection circuits 4-2 to 4 -N other than its own device by wires 8 serving as signal lines. Is also connected to an overcurrent detection circuit other than its own device by a wire 8. When the overcurrent detection circuits 4-1 to 4-N detect an overcurrent, the potential of the wire 8 is changed to a high level. When the potential of the wire 8 becomes high level, the control circuit determines that an overcurrent is detected by an overcurrent detection circuit of another in-vehicle device, and controls the load circuit of the own device to control the battery power line 1a. A predetermined current is passed through

  The load circuits 6-1 to 6-N are load circuits that increase the current flowing through the battery power supply line 1a by the control circuits 5-1 to 5-N. For example, the load circuits 6-1 to 6-N are realized by resistors arranged between the power supply line 1a and the ground GND, and a predetermined voltage is applied from the control circuits 5-1 to 5-N to the load circuit. Thus, a predetermined value of current can be passed through the battery power line 1a.

Next, the operation will be described.
FIG. 2 is a flowchart showing the vehicle fuse blowing method according to the first embodiment, and shows the blow processing of the vehicle fuse 2 when overcurrent is detected by the in-vehicle devices 3-1 to 3-N.
While the in-vehicle devices 3-1 to 3-N are operating, the overcurrent detection circuits 4-1 to 4-N detect overcurrent in the battery power supply line 1a (step ST1).
When none of the overcurrent detection circuits 4-1 to 4-N detects an overcurrent (step ST2; NO), the process returns to step ST1, and the overcurrent detection process is repeated.

For example, when the overcurrent detection circuit 4-1 detects an overcurrent of the battery power supply line 1a (step ST2; YES), it notifies the control circuit 5-1 that the overcurrent has been detected.
When notified that the overcurrent is detected from the overcurrent detection circuit 4-1, the control circuit 5-1 turns on the load circuit 6-1 (voltage application), and a current of a predetermined value (for example, 3 A). Through the battery power line 1a (step ST3).

Subsequently or simultaneously with this, the control circuit 5-1 notifies the other in-vehicle devices 3-2 to 3 -N via the in-vehicle LAN 7 (step ST <b> 4). For example, when there is a malfunction such as failure (cutting) of the wire 8, it is conceivable to notify the detection of overcurrent between the control circuits via the in-vehicle LAN 7.
When the control circuits 5-2 to 5-N of the in-vehicle devices 3-2 to 3-N are notified of the overcurrent detection via the in-vehicle LAN 7, they turn on the load circuits 6-2 to 6-N, respectively (voltage And a predetermined value (for example, 3A) of current is passed through the battery power supply line 1a (step ST5).
As a result, the vehicle fuse 2 disposed in the battery power supply line 1a is blown by flowing the currents of the load circuits 6-1 to 6-N together (step ST6).

For example, if three in-vehicle devices 3-1 to 3-3 are connected to the battery power line 1a and the vehicle fuse 2 is blown at 5A, the load circuit 6 of the in-vehicle device 3-1 is used. -1 flows, 3A flows through the load circuit 6-2 of the in-vehicle device 3-2, and 3A flows through the load circuit 6-3 of the in-vehicle device 3-3. As a result, the vehicle fuse 2 is blown.
As described above, by distributing the current of the load circuit in a plurality of in-vehicle devices, the burden on one in-vehicle device for fusing the vehicle fuse 2 can be reduced, and a fuse is arranged in each in-vehicle device. It does not have to be.

The control circuits 5-1 to 5-N may recognize the overcurrent detection by the overcurrent detection circuits 4-1 to 4-N by the wire 8. In this case, even if any one of the control circuits 5-1 to 5-N or the in-vehicle LAN 7 fails due to some factor, the control circuit that has not failed is detected from any of the overcurrent detection circuits 4-1 to 4-N. The detection of the overcurrent is notified, the load circuits of the own device are turned on, and the vehicle fuse 2 is blown by flowing the currents of these load circuits together.
If load circuits that output a current value at which the vehicle fuse 2 is blown are prepared as the load circuits 6-1 to 6-N, all but one of the control circuits 5-1 to 5-N are prepared. Even if the vehicle breaks down, the vehicle fuse 2 can be blown.
In this way, even if any of the control circuit, the in-vehicle LAN 7 and the wire 8 breaks down, the vehicle fuse 2 can be accurately blown.

  As described above, according to the first embodiment, the in-vehicle devices 3-1 to 3-N detect the overcurrent of the battery power supply line 1a, and the battery power supply. In-vehicle device that detects an overcurrent when an overcurrent is detected by any of the load circuits 6-1 to 6-N and the overcurrent detection circuits 4-1 to 4-N for causing a current to flow through the line 1a And control circuits 5-1 to 5-N for increasing the current of the battery power supply line 1a to blow the vehicle fuse 2 disposed in the battery power supply line 1a. With this configuration, the internal circuit can be accurately protected even if an overcurrent that does not cause the vehicle fuse 2 to melt is generated.

Further, according to the first embodiment, the control circuits 5-1 to 5-N are connected to the battery power supply line 1a in any of the in-vehicle devices 3-1 to 3-N. When an overcurrent is detected from an on-vehicle device that has detected an overcurrent, the load circuit included in each device is operated to detect the current and overcurrent of the load circuit included in the device. The vehicle fuse 2 is blown by flowing together with the current of the load circuit of another on-vehicle device.
By doing in this way, the burden concerning one vehicle equipment can be reduced in order to blow out vehicle fuse 2, and arrangement of the fuse in each vehicle equipment can be omitted.

  Further, according to the first embodiment, the control circuits 5-1 to 5-N are connected to the control circuit of other in-vehicle devices connected to the battery power line via the in-vehicle LAN 7. And the detection of the overcurrent by the overcurrent detection circuit of the other in-vehicle device is notified via the in-vehicle LAN. By comprising in this way, the electric current of a load circuit can be distribute | distributed and distributed by several vehicle equipment.

  Furthermore, according to the first embodiment, the overcurrent detection circuits 4-1 to 4-N are connected to the control circuits 5-1 to 5-N of other in-vehicle devices connected to the battery power supply line. The control circuits 5-1 to 5 -N are connected via the wire 8, and the detection of the overcurrent by the overcurrent detection circuit of another in-vehicle device is notified via the wire 8. With this configuration, even if the control circuit or the in-vehicle LAN 7 breaks down, the vehicle fuse 2 can be accurately blown.

  In the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted within the scope of the invention.

  DESCRIPTION OF SYMBOLS 1 Battery, 1a Battery power line, 2 vehicle fuse, 3-1 to 3-N vehicle equipment, 4-1 to 4-N overcurrent detection circuit, 5-1 to 5-N control circuit, 6-1 to 6- N Load circuit, 7 in-car LAN, 8 wires.

Claims (5)

One or a plurality of in-vehicle devices connected to a battery power line for supplying power from the in-vehicle battery,
An overcurrent detection circuit for detecting an overcurrent of the battery power line;
A load circuit for passing a current through the battery power line;
A control circuit that operates the load circuit to increase a current flowing through the battery power line when the overcurrent is detected by the overcurrent detection circuit, and blows a vehicle fuse disposed in the battery power line; In-vehicle equipment equipped with.   The control circuit detects an overcurrent of the battery power supply line in any of the in-vehicle devices connected to the battery power supply line, and is notified of the detection of the overcurrent from another in-vehicle device that has detected the overcurrent. In this case, by operating a load circuit included in each device, the current of the load circuit included in the device itself and the current of the load circuit of the other in-vehicle device that has detected the overcurrent are caused to flow together and the vehicle fuse The vehicle-mounted device according to claim 1, wherein fusing is performed.   The control circuit is connected to a control circuit of another in-vehicle device connected to the battery power line via an in-vehicle network, and an overcurrent detected by an overcurrent detection circuit of the other in-vehicle device is detected. The in-vehicle device according to claim 2, wherein the detection is notified through the in-vehicle network. The overcurrent detection circuit is connected to a control circuit of another in-vehicle device connected to the battery power line via a signal line,
The in-vehicle device according to claim 2 or 3, wherein the control circuit is notified via the signal line that an overcurrent is detected by an overcurrent detection circuit of the other in-vehicle device. A vehicle fuse fusing method for fusing a vehicle fuse disposed in a battery power supply line for supplying electric power from an in-vehicle battery,
Detecting an overcurrent of the battery power supply line by an overcurrent detection circuit of the in-vehicle device according to claim 1 connected to the battery power supply line;
When an overcurrent of the battery power line is detected in any of the plurality of in-vehicle devices, the overcurrent is detected from the in-vehicle device that has detected the overcurrent to another in-vehicle device connected to the battery power line. A step of notifying detection;
A vehicle equipped with a step of fusing the vehicle fuse by causing the control circuit of the in-vehicle device that has detected the overcurrent and the control circuit of the in-vehicle device that has been notified of the detection of the overcurrent to flow the currents of the respective load circuits together. Fuse blowing method.

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