JP2016113112A - Wiring harness and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring harness capable of achieving diameter reduction and weight reduction of communication wires.SOLUTION: A wiring harness including a trunk line 3 consisting of a pair of communication wires, and one or a plurality of branch lines 4a, 4b, and 4c, each of which consists of a pair of communication wires connected to each of the pair of communication wires of the trunk line 3, is configured so that each of two first communication devices 6a and 6b connected to the two end parts of the trunk line 3, and one or a plurality of second communication devices 1a, 1b, and 1c connected to the branch lines 4a, 4b, and 4c perform communication. A resistance value per unit length of the communication wires constituting the branch lines 4a, 4b, and 4c is larger than the resistance value per unit length of the communication wires constituting the trunk line 3.SELECTED DRAWING: Figure 1

Description

  The present invention includes a trunk line composed of a pair of communication lines and one or a plurality of branch lines each composed of a pair of communication lines connected to the pair of communication lines, and two first lines connected to both ends of the trunk line. The present invention relates to a communication device, a wire harness in which each of the second communication devices connected to a branch line performs communication, and a communication system including the wire harness.

  In a vehicle, a large number of mounted electronic devices are connected via a communication line and communicate with each other to perform cooperative operation, thereby realizing vehicle travel control, vehicle interior environmental control, and the like. In mounted electronic devices, CAN (Controller Area Network) is widely adopted as a communication protocol.

  In general, in a communication system that employs a CAN communication protocol, a twisted pair cable in which a pair of communication lines are combined is used, and a terminating resistor is interposed between the communication lines at both ends of the twisted pair cable. . Each electronic device detects a dominant when the potential difference between the pair of communication lines exceeds a threshold, and detects recessive when the potential difference is equal to or less than the threshold.

In general, a communication system adopting a CAN communication protocol adopts a bus type or star type network topology. In the bus type network topology, each electronic device is connected to each branch line branched from a different branch point on the trunk line used for communication in common with other electronic devices. In the star network topology, each electronic device is connected to each branch line branched from one branch point on the trunk line.
For example, each electronic device performs data transmission / reception with a dominant corresponding to data 0 and a recessive corresponding to data 1.

  Patent Document 1 discloses a data communication system in which transmission lines connected to individual subscriber terminal stations are connected to one passive network node in a star shape. The transmission line has a frequency dependent attenuating element, for example a ferrite bead. Good characteristic impedance matching of high-frequency noise signals is performed by simultaneous and free selection of system parameters set to a steady data symbol state.

JP 7-700463 Gazette

  In the communication system employing the CAN communication protocol as described above, the reception voltage is lowered due to the resistance of the communication line itself. Therefore, priority is given to reducing the resistance value of the communication line, and the communication line is made thinner and lighter. There is still a problem that there is still room for improvement.

This invention is made | formed in view of the above situations, and it aims at providing the wire harness which can aim at the diameter reduction and weight reduction of a communication wire.
Another object of the present invention is to provide a communication system including a wire harness capable of reducing the diameter and weight of a communication line.

  A wire harness according to the present invention includes a trunk line composed of a pair of communication lines, and one or a plurality of branch lines composed of a pair of communication lines connected to the pair of communication lines, and is connected to both ends of the trunk line. In the wire harness configured so that each of the two first communication devices and one or a plurality of second communication devices connected to the branch line communicate with each other, the communication line constituting the branch line is per unit length. The resistance value is larger than the resistance value per unit length of the communication line constituting the trunk line.

  In this wire harness, the trunk line is composed of a pair of communication lines, and one or more branch lines are composed of a pair of communication lines connected to the pair of communication lines of the trunk line. Two first communication devices connected to both ends of the main line and one or a plurality of second communication devices connected to the branch line each perform communication. The communication line constituting the branch line has a resistance value per unit length larger than the resistance value per unit length of the communication line constituting the trunk line.

  The wire harness according to the present invention is characterized in that a resistance value per unit length of the communication line constituting the branch line is greater than 70 mΩ / m and not greater than 400 mΩ / m.

  In the wire harness according to the present invention, the material of the communication line constituting the branch line is Cu-Fe (copper iron alloy), Cu-Sn (bronze), Cu-Ag (copper silver alloy), Al (aluminum), Al -It is either Cu (aluminum bronze) alloy or metal.

  A communication system according to the present invention includes a wire harness according to the present invention, two first communication devices connected to both ends of a trunk line included in the wire harness, and one or more connected to branch lines included in the wire harness. And a second communication device.

  In this communication system, the wire harness according to the present invention is provided, two first communication devices are connected to both ends of a main line provided in the wire harness, and one or a plurality of second communication devices are connected to a branch line provided in the wire harness. Is connected.

  According to the wire harness according to the present invention, a wire harness capable of reducing the diameter and weight of a communication line can be realized.

  According to the communication system according to the present invention, it is possible to reduce the diameter and weight of the communication wire of the wire harness.

It is a circuit diagram showing a schematic structure of an embodiment of a wire harness and a communication system according to the present invention. It is explanatory drawing for demonstrating the relationship between each resistance value per unit length of each communication line which comprises a trunk line and a branch line, and the voltage drop of a signal voltage. It is a circuit diagram which shows the other schematic structure of embodiment of the wire harness and communication system which concern on this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.

FIG. 1 is a circuit diagram showing a schematic configuration of an embodiment of a wire harness and a communication system according to the present invention.
This communication system includes ECUs (Electronic Control Units) 1a, 1b, and 1c that are mounted on a vehicle, and terminal ECUs 6a and 6b that are also mounted on the vehicle. The termination ECU 6a has a transmission / reception circuit 2a connected to one end of the trunk line 3 composed of a pair of communication lines via a termination circuit 5a, and the termination ECU 6b is connected to the other end of the trunk line 3 via a termination circuit 5b. The transmission / reception circuit 2b is provided. The terminal ECUs 6a and 6b correspond to the first communication device of the present invention, and the ECUs 1a, 1b and 1c correspond to the second communication device of the present invention.

  The ECU 1a is connected to a branch line 4a branched from a branch point A in the middle of the trunk line 3, the ECU 1b is connected to a branch line 4b branched from a branch point B in the middle of the trunk line 3, and the ECU 1c is connected to a branch point in the middle of the trunk line 3 It is connected to a branch line 4c branched from C. The branch point B is closer to the end ECU 6b than the branch point A, and the branch point C is closer to the end ECU 6b than the branch point B. The branch lines 4a, 4b, and 4c are each composed of a pair of communication lines that are branched by connecting to the pair of communication lines of the trunk line 3, respectively.

Here, the trunk line 3 and the branch lines 4a, 4b, and 4c are twisted pair cables having characteristic impedance that can operate as a CAN (Controller Area Network) bus.
Further, the communication lines constituting the branch lines 4a, 4b, 4c have a resistance value per unit length larger than that of the communication line constituting the main line 3, for example, the resistance value of the communication line constituting the main line 3 is 70 mΩ. The resistance value of the communication lines constituting the branch lines 4a, 4b, and 4c is greater than 70 mΩ / m and not greater than 400 mΩ / m.

Further, the cross-sectional area of the communication lines that constitute the branch lines 4a, 4b, and 4c is smaller than that of the communication line that constitutes the trunk line 3, for example, 0.13 sq (mm ² ). In this case, the branch lines 4a, 4b, The material of the communication line constituting 4c may be the same material as that constituting the trunk line 3, and the weight of the wire harness can be reduced.
The materials of the communication lines constituting the branch lines 4a, 4b, 4c are Cu-Fe (copper iron), Cu-Sn (bronze), Cu-Ag (copper silver alloy), Al (aluminum), Al-Cu (aluminum bronze). The diameter of the branch lines 4a, 4b, 4c and the weight of the wire harness can be reduced depending on the strength and weight of the material.

  FIG. 2 is an explanatory diagram for explaining the relationship between each resistance value per unit length of each communication line constituting the trunk line 3 and the branch lines 4a, 4b, and 4c, and the voltage drop of the signal voltage. Here, the resistors 7a and 7b distributed on the communication lines constituting the trunk line 3 and the resistors 8a and 8b distributed on the communication lines constituting the branch lines 4a, 4b and 4c are displayed as concentrated constants.

As shown in FIG. 2A, when communicating between the termination ECUs 6a and 6b, since the input resistances (for example, 40 kΩ) of the transmission / reception circuits 2a and 2b are very large, the termination resistances (for example, 120Ω) of the termination circuits 5a and 5b The resistances 7a and 7b of the communication lines constituting the trunk line 3 are connected in approximately series.
In this case, assuming that the termination ECU 6b is the reception side, the reception voltage V2b of the transmission / reception circuit 2b has a relatively small resistance value of each termination resistance of the termination circuits 5a and 5b. It is greatly affected. Therefore, the resistance values of the resistors 7a and 7b distributed on the communication lines constituting the trunk line 3 need to be low.

On the other hand, as shown in FIG. 2B, for example, when the ECU 1a receives, the very large input resistance (for example, 40 kΩ) of the ECU 1a and the resistances 8a and 8b of each communication line constituting the branch line 4a are connected in series. Will be.
In this case, the received voltage of the ECU 1a has a very large input resistance of the ECU 1a (the flowing current is substantially 0), so the influence of the voltage drop due to the resistances 8a and 8b of each communication line can be ignored. Therefore, the resistances 8a and 8b distributed in each communication line constituting the branch line 4a do not need to have a low resistance value as in each communication line constituting the trunk line 3. However, it is desirable to set it to 400 mΩ or less in order to prevent the connection portion with the terminal of the connector portion connecting the main line 3 and the branch line 4a from being disconnected.

  In the wire harness and the communication system of the present embodiment, the ECUs 1a, 1b, and 1c are connected to branch lines 4a, 4b, and 4c branched from different branch points A, B, and C, respectively, by a bus type (FIG. 1). As described above, as shown in FIG. 3, even if the ECUs 1a, 1b, and 1c are connected to the branch lines 4a, 4b, and 4c branched from one branch point D, similar effects can be obtained. Can do.

  The embodiments disclosed herein are illustrative in all respects and should not be considered as restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of claims for patent, and is intended to include all modifications within the scope and meaning equivalent to the scope of claims for patent.

1a, 1b, 1c ECU (second communication device)
2a, 2b Transmission / reception circuit 3 Trunk line 4a, 4b, 4c Branch line 5a, 5b Termination circuit 6a, 6b Termination ECU (first communication device)
7a, 7b, 8a, 8b resistance

Claims (4)

Two first communication devices comprising a trunk line composed of a pair of communication lines and one or a plurality of branch lines each composed of a pair of communication lines connected to the pair of communication lines, respectively, connected to both ends of the trunk line; And a wire harness configured such that each of the one or more second communication devices connected to the branch line performs communication,
The communication line constituting the branch line has a resistance value per unit length larger than a resistance value per unit length of the communication line constituting the trunk line.   The wire harness according to claim 1, wherein a resistance value per unit length of the communication line constituting the branch line is greater than 70 mΩ / m and equal to or less than 400 mΩ / m.   The wire harness according to claim 1 or 2, wherein a material of the communication line constituting the branch line is any one of an alloy or a metal of Cu-Fe, Cu-Sn, Cu-Ag, Al, Al-Cu.   A wire harness according to any one of claims 1 to 3, comprising two first communication devices connected to both ends of a trunk line provided in the wire harness, and one or more connected to branch lines provided in the wire harness A communication system comprising: a second communication device.

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