JP2010081420A - Failure mode specifying apparatus for on-vehicle communication line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a failure mode specifying apparatus capable of specifying a short-circuiting occurrence mode that is generated on a two-wire type CAN communication line constituted of a High line and a Low line. <P>SOLUTION: A failure mode specification apparatus includes: a High line and a Low line for inspection are connector-connected to a High line and a Low line of a two-wire type CAN communication line; a resistor circuit for inspection to which other terminals of the High line and the Low line for inspection are connected is connected; a potential measuring section connected to one part of the resistor circuit for inspection is connected; and a failure mode determining section connected to the potential measuring section for specifying a short-circuiting occurrence mode of the High line and the Low line, on the basis of a potential measured by the potential measuring section are provided. In the resistor circuit for inspection, a plurality of resistors for inspection are connected, in series, to a circuit connecting a power supply section and a ground, the other terminals of the High line and the Low line for inspection are connected between the resistors for inspection, respectively, and the potential measurement section is connected to one part of the resistor circuit for inspection, and is held in between the resistors for inspection connected to the High line and the Low line. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a failure mode identification device for an in-vehicle communication line, and more specifically, when a short abnormality occurs in a CAN communication circuit mounted on an automobile, the short occurrence mode can be identified.

  2. Description of the Related Art A two-wire multiplex communication line whose protocol is CAN is widely used as a communication line mounted on an automobile. The CAN communication line is composed of a twisted pair electric wire obtained by twisting and combining a high line (hereinafter abbreviated as H line) and a low line (hereinafter abbreviated as L line). Are connected to electronic components such as a communication network inside the automobile.

  Conventionally, failure diagnosis of a CAN communication line is performed by connecting a diagnosis connector to a branch line branched from a trunk line of the CAN communication line, connecting the diagnosis connector to a diagnosis apparatus of an external tool, and connecting each of the diagnosis apparatus and the CAN communication line. By communicating with the node device, the node device in which an abnormality has occurred or the disconnected communication line is identified.

However, when an abnormality occurs due to a short in the CAN communication line, a communication abnormality occurs in the entire CAN communication circuit. Therefore, in the failure diagnosis by the diagnosis apparatus, the abnormality occurs in the node or the communication line. Cannot identify the location of the abnormality. In addition, the short occurrence mode cannot be specified. That is, it cannot be specified whether the short circuit is a short circuit to the power supply line, a short circuit to the ground, or a short circuit between the H line and the L line.
Therefore, it is necessary to inspect each communication line one by one using a tester or the like in order to specify a failure location and a failure mode, and there is a problem that workability is poor and work takes time.

JP-A-2004-252963 (Patent Document 1) has been proposed as a failure diagnosis method for this type of CAN communication line. In Patent Document 1, a resistance value between an H line and an L line of a CAN communication line is measured, and an abnormal part is specified by a combination of the measurement result and an abnormal code stored in advance.
In the failure diagnosis method of Patent Document 1, it is possible to detect a case where a CAN communication line is disconnected, a branch line is disconnected with a connector connected to a diagnosis device, and a short circuit occurs between the H line and the L line. It is impossible to detect a short circuit to the battery power line or a short circuit to the ground.

Moreover, in the failure detection method of Unexamined-Japanese-Patent No. 2006-191404 (patent document 2), each potential of the H line and the L line of the CAN communication line is measured, and whether or not a short has occurred based on the measurement result. Is detected.
In Patent Document 2, it is necessary to measure potentials at two locations of the H line and the L line. In addition, a short circuit to the battery power supply and a short circuit to the ground that could not be detected in Patent Document 1 can be detected. However, there is a problem that a short circuit cannot be detected when a short circuit occurs between the H line and the L line. .

JP 2004-252963 A JP 2006-191404 A

  As described above, in the conventionally proposed CAN communication line failure detection method, the shorts that can be detected are limited. Therefore, even if an abnormality due to the short occurs, the short occurrence mode cannot be specified.

  The present invention is intended to solve the above-described problem. When a short circuit occurs in a two-wire CAN communication line having an H line and an L line, it can be easily performed on either the H line or the L line. It is an object of the present invention to be able to specify whether a short-circuit to a wire or a short to ground, a short-circuit between the H line and the L-line, or a short-circuit occurrence mode.

In order to solve the above-described problem, the present invention is a failure mode identifying device that identifies a short-circuit occurrence mode when a short-circuit occurs in a two-wire CAN communication line connected to a node,
High line and Low line for inspection connected to the High line and Low line of the two-wire CAN communication line,
An inspection resistance circuit to which the other ends of the inspection High line and the Low line are connected;
A potential measurement unit connected to one location of the inspection resistance circuit;
A failure mode determination unit that is connected to the potential measurement unit and identifies a short line occurrence mode of the High line and the Low line based on the potential measured by the potential measurement unit;
The inspection resistance circuit has a plurality of inspection resistors connected to a circuit connecting a power supply unit and a ground, and the other ends of the inspection High line and the Low line are respectively between the inspection resistors. A failure of an in-vehicle communication line, characterized in that the potential measuring unit is connected to one place of the inspection resistance circuit that is connected and sandwiched between inspection resistances connected to the High line and the Low line A mode identification device is provided.

In the present invention, with the above-described configuration, when a short-circuit abnormality occurs in a two-wire CAN communication line composed of an H line and an L line connected to a node, the short-circuit occurrence mode is defined as an H line and an L line. Or a short circuit to the power line on the H line side or a short circuit to the ground, or a short circuit to the power line on the L line side or a short circuit to the ground.
That is, in the abnormality diagnosis apparatus of the present invention, the H line and the L line are respectively connected between the inspection resistors provided in the inspection resistor circuit connected to the power source and the ground. The potential at one place between the connected inspection resistors is measured, and the short-circuit occurrence mode is specified by the difference in the measured potential depending on the short-circuit occurrence mode.
In this way, the connector connected to the H line and L line of the CAN communication line is connected to the connector of the failure mode specifying device, and the short-circuit occurrence mode can be specified simply by measuring the potential of one point of the resistance circuit for inspection. can do.

  The failure mode determination unit connected to the potential measuring unit includes a short circuit between the H line and the L line, a short circuit to the power line of the H line, a short circuit to the ground of the H line, a short circuit to the power line of the L line, L A potential range in which a short circuit to the ground of each line can be specified is stored, and a short-circuit occurrence mode is specified by referring to the stored potential range from the potential measured by the potential measuring unit.

The inspection resistor circuit includes four or more inspection resistors connected in series between the DC power supply unit and the ground, and both the inspection H line 22 and the L line 23 are adjacent inspection resistors. It is preferable to connect between them.
Specifically, as the inspection resistor, a first resistor to a fourth resistor are connected in series, an H line is connected between the first resistor and the second resistor, and an L between the third resistor and the fourth resistor is connected. Lines are connected, and one point between the second resistor and the third resistor is connected to the potential measuring unit.

Further, it is preferable that the resistance values of the first resistor and the second resistor sandwiching the connection portion with the H line are made different, and the resistance values of the third resistor and the fourth resistor sandwiching the connection portion with the L line are made different.
For example, when the voltage supplied from the DC power supply unit is 12V, the resistance values of the first resistor and the third resistor are 70Ω, and the resistance values of the second resistor and the fourth resistor are 23Ω.
Thus, by making the resistance values of the test resistors different, a significant difference can be generated in the potential measured according to the short-circuit occurrence mode.

  In addition, a display unit that displays the determination result of the failure mode determination unit is provided, or a determination result output unit that is connected to the display unit is provided.

  As described above, in the failure mode identification device of the present invention, the short-circuit occurrence mode can be easily identified simply by connecting the two-wire CAN communication line in which the short abnormality has occurred. In addition, the failure mode specifying device can specify the short-circuit occurrence mode only by measuring the potential of one point of the inspection resistance circuit connecting the H line and the L line, and the device itself has a simple configuration. In addition, it is possible to quickly specify the short occurrence mode.

Embodiments of a failure mode measuring apparatus according to the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the H line (High line) 2 and the L line (Low line) 3 of the CAN communication line 1 forming the two-wire multiplex communication circuit wired to the automobile are connected to the main connector L1 with the joint connector 5. The circuit board 6 accommodated in the joint connector 5 is branched and connected, and the trunk line L1 is branched and connected to the branch lines L2 to L4. Specifically, the terminals (not shown) in the connector 10 connected to the terminals of the trunk line L1 and branch lines L2 to L4 connected to the node 9 are fitted into the H line terminal 7 and the L line terminal 8 of the joint connector 5, respectively. Match.

  When a short circuit abnormality occurs in any of the nodes 9 to be inspected connected to the trunk line L1 and the branch lines L2 to L4, the connector 10 of the CAN communication line 1 connected to the node 9 in which the short circuit abnormality has occurred is separated from the joint connector 5. 2 is connected to the connector 21 of the failure mode identification device 20 shown in FIG. 2, and the location where the short circuit occurs, that is, the short generation mode is identified.

The failure mode specifying device 20 shown in FIG. 2 includes the inspection H line 22 and the inspection L line 23 that are connected to the connector 21 at one end, and in addition to the inspection H line 22 and L line 23. The end is connected to the inspection resistance circuit 24.
The test resistance circuit 24 includes a first resistor 27, a second resistor 28, a second resistor 28, a circuit connecting a DC power supply unit 25 connected to a battery and a ground 26, from the DC power supply unit 25 side to the ground 26 side. Three resistors 29 and a fourth resistor 30 are sequentially provided in series.
The inspection H line 22 is connected between the first resistor 27 and the second resistor 28, and the inspection L line 23 is connected between the third resistor 29 and the fourth resistor 30.
In the present embodiment, the voltage of the DC power supply unit 25 is 12 V, the resistance values of the first resistor 27 and the third resistor 29 are 70Ω, and the resistance values of the second resistor 28 and the fourth resistor 30 are 23Ω.
The resistance value is changed in this way in order to provide a large difference in the potential measured by the potential measuring device 32 described later according to the short-circuit occurrence mode.

  A potential is measured by connecting one point between the second resistor 28 and the third resistor 29 to the potential measuring device 32. The potential measured by the potential measuring device 32 is output to the failure mode determination unit 34, and the failure mode determination unit 34 identifies the short-circuit occurrence mode. The short-circuit occurrence mode specified by the failure mode determination unit 34 is displayed on the failure determination result display unit 35.

  In the failure mode determination unit 34, the H line and the L line are shorted, the H line is shorted to the power line, the H line is shorted to the ground, the L line is shorted to the power line, and the L line is shorted to the ground. Is stored, and the short-circuit occurrence mode is specified by referring to the stored potential range from the potential measured by the potential measuring device 32.

As shown in the table of FIG. 3, the stored potential range and failure mode are composed of a table in which the failure mode and the potential determination range (V) are associated with each other. The failure mode is specified depending on which potential determination range the potential measured by the potential measuring device 32 falls into.
As shown in the table of FIG. 3, if the measured potential is 6 V, it is determined that no short circuit has occurred in the CAN communication line, and it is determined that the short circuit has occurred in the inspected node 9.
On the other hand, if the measured potential is 2.97 V, it is within the range of 1.5 to 4.0 of the potential determination range, so it is determined that the H line 2 and the L line 3 are short-circuited. If the measured potential is 9.62 V, the potential is within the range of 8.0 to 11.0 in the potential determination range, and thus it is determined that the H line is a short circuit to the power supply line.

  As described above, in the failure mode specifying device 20, the H line and the L line are shorted, the H line is shorted to the power line, the H line is shorted to the ground, the L line is shorted to the power line, and the L line is grounded. When the short circuit occurs, the inspection H line 22 and the L line 23 are connected to the first to fourth resistances 27 to 27 of the inspection resistance circuit 24 so that the potential measured by the potential measuring device 32 is different. 30 is connected. Therefore, the short occurrence mode can be specified by the potential measured by the potential measuring device 32.

  The short-circuit occurrence mode specified by the failure mode determination unit 34 is displayed on the failure determination result display unit 35 so that the short-circuit occurrence mode can be recognized at a glance.

  The present invention is not limited to the above-described embodiment. For example, the resistance values of the first to fourth resistors 27 to 30 are not limited to the above, and a difference may be generated in the potential measured for each short-circuit occurrence mode. If possible, the resistance value can be set arbitrarily.

It is a perspective view which shows the connection form of the 2-wire type CAN communication circuit wired to a motor vehicle. It is a block diagram of the failure mode specific device of this invention. It is a table | surface which shows the relationship between the failure mode memorize | stored in the failure mode determination part, and an electric potential determination range.

Explanation of symbols

1 CAN communication line 2 H line (High line)
3 L line (Low line)
9 Node 10 Connector 20 Failure Mode Identification Device 21 Connector 22 Inspection H Line 23 Inspection L Line 24 Inspection Resistance Circuit 25 DC Power Supply Unit 26 Ground 27-30 First Resistance to Fourth Resistance 32 Potential Measuring Device 34 Failure mode judgment part 35 Failure judgment result display part

Claims (5)

A failure mode identifying device that identifies a short-circuit occurrence mode when a short-circuit occurs in a two-wire CAN communication line connected to a node,
High line and Low line for inspection connected to the High line and Low line of the two-wire CAN communication line,
An inspection resistance circuit to which the other ends of the inspection High line and the Low line are connected;
A potential measurement unit connected to one location of the inspection resistance circuit;
A failure mode determination unit that is connected to the potential measurement unit and identifies a short line occurrence mode of the High line and the Low line based on the potential measured by the potential measurement unit;
The inspection resistance circuit has a plurality of inspection resistors connected to a circuit connecting a power supply unit and a ground, and the other ends of the inspection High line and the Low line are respectively between the inspection resistors. A failure of an in-vehicle communication line, characterized in that the potential measuring unit is connected to one place of the inspection resistance circuit that is connected and sandwiched between inspection resistances connected to the High line and the Low line Mode specific device.   The failure mode determination unit connected to the potential measuring unit includes a short circuit between the High line and the Low line, a short circuit to the power line of the High line, a short circuit to the ground of the High line, a short circuit to the power line of the Low line, Low 2. A potential range in which a short circuit to the ground of each line can be specified is stored, and a short-circuit occurrence mode is specified by referring to the stored potential range from the potential measured by the potential measuring unit. The failure mode specifying device for the in-vehicle communication line described in 1.   The inspection resistor circuit has four or more inspection resistors connected in series between the DC power supply unit and the ground, and the High line and the Low line are both connected between adjacent inspection resistors. The in-vehicle communication line failure mode specifying device according to claim 1 or 2.   The resistance values of the pair of inspection resistors sandwiching the connection portion with the High line are made different from each other, and the resistance values of the pair of inspection resistors sandwiching the connection portion with the Low line are made different from each other. Item 4. The failure mode identifying device for a vehicle-mounted communication line according to any one of items 3 to 4.   The vehicle-mounted communication line according to any one of claims 1 to 4, further comprising a display unit that displays a determination result of the failure mode determination unit, or a determination result output unit that is connected to the display unit. Abnormality diagnosis device.

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