Trunk line structure in in-vehicle network and connector for in-vehicle network

It is aimed to build a trunk line of an in-vehicle network having low connection resistance. The in-vehicle network is composed of a trunk line (1) and branch lines (2) branched from branch points (3) arranged at a plurality of intermediate positions of the trunk line (19 via connectors (CO) and to be connected to electronic control units (U). A bypass bypassed toward the connector (CO) from the trunk line (1) is formed at each branch point (3) of the branch line (1), and an exposed part of a core (7) is formed in this bypass and connected to a trunk line terminal (6). A branch line terminal (8) connected to an end of the branch line (2) and the trunk line terminal (6) are connected inside the connector (CO).

BACKGROUND

1. Field of the Invention

The present invention relates to a trunk line structure in an in-vehicle network and a connector for in-vehicle network.

2. Description of the Related Art

Conventionally, an in-vehicle network called CAN is installed in an automotive vehicle and communication is conducted through a wiring harness in which a plurality of nodes (electronic control units) constitute communication transmission paths. Such a conventional in-vehicle network is known from Japanese Unexamined Patent Publication No. 2009-176688.

Generally, in the case of connecting a plurality of nodes, a connection method called a line-type (bus-type) connection method is known in CAN communication. The line type connection method connects each node via a plurality of branch lines branched from a trunk line.

In Japanese Unexamined Patent Publication No. 2009-176688, relay joint connectors are disposed at branch points where the respective branch lines are branched from the trunk line. A housing of the relay joint connector is formed with first and second fitting portions open in opposite directions, and busbars are arranged in two upper and lower stages inside. A plurality of tab-like terminals are formed to project side by side on each busbar.

On the other hand, each of the trunk line and the branch lines is formed of a twisted pair cable formed by twisting and combining two wires. The trunk line and the branch lines have a wire end at each branch point. A female terminal is connected to an end of each wire and connected to the corresponding tab-like terminal. In this way, it has been made possible to relay the trunk line and branch the branch lines.

In the case of the above structure, the trunk line is relayed at each connection point by way of the following many connected parts.

(i) Connected part of an end of the trunk line and the female terminal

(ii) Connected part of the female terminal and the tab-like terminal

(iii) Connected part of another tab-like terminal in the same busbar and another female terminal connected to another end of the trunk line

(iv) Connected part of the other female terminal and the other end of the trunk line

As just described, since many connection components are required and connection is made by way of many connected parts in the conventional structure, connection resistance may increase.

The present invention was completed based on the above situation and aims to provide a trunk line structure in an in-vehicle network capable of simplifying a structure for connecting trunk lines and reducing connection resistance and a connector suitably usable in an in-vehicle network.

SUMMARY

The invention is directed to a trunk line structure in an in-vehicle network in which plural electronic control units communicate with each other via a wiring harness. The wiring harness is composed of a trunk line and branch lines branched via connectors from branch points arranged at intermediate positions of the trunk line to be connected to the electronic control units. A part of the wiring harness constituting the trunk line is formed with bypasses bypassed toward the connectors from the trunk line at the branch points. A core of the wiring harness is exposed at the bypass and a trunk line terminal is connected to an exposed part of the core. A branch line terminal connected to an end of the branch line and the trunk line terminal are connectable inside the connector.

The invention also is directed to a connector for in-vehicle network to be interposed between a trunk line and a branch line in an in-vehicle network in which plural electronic control units communicate with each other via a wiring harness composed of the trunk line and the branch lines branched from branch points arranged intermediate positions of the trunk line. The wiring harness constituting the trunk line is formed with bypasses bypassed toward the connectors from the trunk line at the branch points. A core of the wiring harness is exposed at the bypass and a trunk line terminal is connected to an exposed part of the core. A branch line terminal is connected to an end of the branch line. A first accommodating portion for accommodating the trunk line terminal is formed to be open on one surface of a housing of the connector. A second accommodating portion for accommodating the branch line terminal is formed to be open on an opposite surface such that the both accommodating portions substantially coaxially face each other. First and second retainer mounting holes are open on the housing to communicate with the first and second accommodating portions. The trunk line terminal and the branch line terminal are retained and held in the housing only by the retainers mounted into the retainer mounting holes that lock the terminals.

Conventionally, a trunk line is cut between branch points and the branch points are connected using terminals. However, according to the trunk line structure of the present invention, the branch points in the trunk line can be connected without using terminals. Thus, terminal connected parts are reduced by that much, a trunk line connection structure can be simplified and connection resistance can also be reduced.

According to the connector for in-vehicle network of the present invention, the trunk line connection structure can be simplified, which can also contribute to a reduction of connection resistance. In addition, the trunk line terminal and the branch line terminal are locked only by the retainers in the connector of the present invention. That is, since the connector has no lance structure for locking the terminals, internal structures of the first and second accommodating portions can be simplified and, eventually, manufacturing cost can also be reduced due to the simplification of a mold structure.

The wiring harness of the trunk line structure in the in-vehicle network of the present invention may be formed of twisted pair cables. This configuration is effective in noise reduction.

The bypass may be folded continuously without interruption from the trunk line while forming a substantially U shape, and the exposed part of the core may be formed in a folded part and connected to the trunk line terminal. According to this configuration, the wiring harness is connected to the trunk line terminal while being kept continuous without cutting the wiring harness at the branch point of the trunk line. Thus, connection reliability can be enhanced.

The bypass may be folded from the trunk line while forming a substantially U shape and cut in a folded part. Additionally, the exposed part of the core may be formed at each of both cut end parts, and the exposed parts may be fastened and connected to the trunk line terminal. If no cut is made in the bypass, it is difficult to bend the wiring harness in connecting the wiring harness to the trunk line terminal. However, by cutting the folded part and fastening the cut end parts to the trunk line terminal as described above, a connecting operation to the trunk line terminal can be easily performed.

The exposed parts may be welded and connected to the trunk line terminal. According to this configuration, connection to the trunk line terminal is easy and connection reliability can be further enhanced.

Next, first and second specific embodiments of the present invention are described with reference to the drawings.

DETAILED DESCRIPTION

FIG. 1shows a part of an in-vehicle network called CAN (Control Area Network), in which a plurality of electronic control units U can communicate with each other via a wiring harness WH.

The wiring harness WH is composed of a trunk line1and branch lines2branched from this trunk line1at a plurality of branch points3and connected to electronic control units U at branch destinations thereof. Further, the trunk line1and the respective branch lines2are each formed by a twisted pair cable formed by twisting two wires W (communication wires).

The trunk line1is formed with a bypass4toward a connector CO at each branch point3, and the bypass4returns to the trunk line1again by way of a trunk line terminal6to be accommodated into a housing5of the connector CO. In the first embodiment, as shown inFIG. 6(A), a coating of the wire W is removed at a folded part of the bypass4to expose a core7.

The trunk line terminal6is a female terminal as shown inFIGS. 2 and 6(A) and composed of a terminal connecting portion6A to be connected to a branch line terminal8and a wire connecting portion6B arranged behind terminal connecting portion6A. The wire connecting portion6B is composed of a wire barrel6B-1folded into a U-shape and to be collectively crimped and connected to the exposed core7and an insulation barrel6B-2to be collectively crimped and connected to a coating part of the folded wire W (seeFIGS. 2 and 6(B)).

As described above, one end side of each wire W of the twisted pair cable constituting each branch line2is connected to the electronic control unit U and the other end side is connected to the branch line terminal8. The branch line terminal8is a male terminal and composed of a terminal connecting portion8A including a tab portion8C connectable to the terminal connecting portion6A of the trunk line terminal6and a wire connecting portion8B arranged behind the terminal connecting portion8A as shown inFIG. 2. Although not shown in detail, the wire connecting portion8B is composed of a wire barrel8B-1to be crimped and connected to the core7exposed at an end part of each wire W of the twisted pair cable and an insulation barrel8B-2to be crimped and connected to a coating part of each wire W.

Next, the configuration of the connector CO is described with reference toFIGS. 2 to 5. The housing5of the connector CO is made of synthetic resin and shaped to be longer in a horizontal direction than in a vertical direction as shown inFIGS. 2 and 3. Further, two first accommodating portions9and two second accommodating portions10are provided laterally side by side in the housing5(seeFIGS. 4 and 5). The first accommodating portion9is for accommodating the trunk line terminal6and the second accommodating portion10is for accommodating the branch line terminal8.

As shown inFIG. 2, a partition wall11is provided between the first and second accommodating portions9,10in a central part of the housing5in a longitudinal direction (horizontal direction). The first and second accommodating portions9,10are substantially coaxially arranged across this partition wall11. Surfaces of the partition wall11facing the first accommodating portions9and the second accommodating portions10respectively serve as front-stop surfaces configured to come into contact with the trunk line terminals6or the branch line terminals8to prevent any forward movements. Further, the partition wall11is formed with a pair of through holes12for allowing the tab portions8C of the branch line terminals8to pass therethrough, thereby allowing the both first and second accommodating portions9,10to communicate with each other.

Further, since the housing5cannot be formed with locking lances normally provided in the connector CO since the pairs of first and second accommodating portions9,10are coaxially formed by removing molds in opposite directions. Any of the trunk line terminals6and the branch line terminals8is retained only by a retainer13,14. Specifically, as shown inFIG. 3, first and second retainer mounting holes15,16are open on the lower surface of the housing5. The both retainer mounting holes15,16are respectively formed to collectively communicate with the pair of first accommodating portions9and the pair of second accommodating portions10.

The first and second retainers13,14are mounted into the both retainer mounting holes15,16. As shown inFIG. 2, the both retainers13,14are formed with locking projections13A,14A capable of locking the respective terminal connecting portions6A,8A of the both trunk line terminals6and the both branch line terminals8. Further, although not shown in detail, the both retainers13,14are held at two positions, i.e. a partial locking position and a full locking position, with respect to the housing5. When the both retainers13,14are at the partial locking position, the respective locking projections13A,14A are located outside insertion areas for the trunk line terminals6and the branch line terminals8to permit the insertion and withdrawal of the respective terminals6,8. However, when the both retainers13,14are at the full locking position (state shown inFIG. 2), the respective locking projections13A,14A are located in the insertion areas for the trunk line terminals6and the branch line terminals8and respectively lock the rear ends of the terminal connecting portions6A of the trunk line terminals6or the terminal connecting portions8A of the branch line terminals8to retain and hole these terminals6,8.

Next, functions and effects of the first embodiment are described. In the first embodiment, the bypass4is formed at each branch point3of the trunk line1and the core7is exposed in the folded part of the bypass4in configuring the trunk line1. Then the wire barrel6B-1of the trunk line terminal6is crimped to this exposed part of the core7. If the above operation is repeated at each branch point3, the trunk line1can be configured.

As just described, the trunk line1can be continuous without interruption at each branch point3of the branch line1according to the first embodiment. Thus, terminals are not required unlike before, wherefore the structure of the trunk line1can be simplified and high connection reliability can be also realized.

Further, in the case of connecting each electronic control unit U branched from the trunk line1via the branch line2, the aforementioned trunk line terminals6are respectively accommodated into the both first accommodating portions9of the connector CO with the first retainer13held at the partial locking position. If the first retainer13is moved to the full locking position thereafter, the locking projections13A of the first retainer13lock the rear ends of the terminal connecting portions6A of the trunk line terminals6. Thus, the trunk line terminals6are retained and locked in the connector CO.

On the other hand, after being respectively connected to the end parts of the both wires W constituting the branch line2, the branch line terminals8are accommodated into the second accommodating portions10of the connector CO. Also in this case, the second retainer14is held at the partial locking position. When the branch line terminals8are inserted to a proper depth position into the second accommodating portions10, the tab portions8C pass through the through holes12of the partition wall11and are inserted into the terminal connecting portions6A of the trunk line terminals6to be electrically connected. If the second retainer14is moved to the full locking position thereafter, the locking projections14A of the second retainer14lock the rear ends of the terminal connecting portions8A of the branch line terminals8. Thus, the branch line terminals8are retained and locked in the connector CO.

Since the housing5of the connector CO of the first embodiment is provided with the first and second accommodating portions9,10coaxially facing each other as described above, no locking lance is formed in the housing5. Since a locking lance is generally complicated in shape in many cases, having no such locking lance contributes to the simplification of the internal structure of the housing5as a result.

FIGS. 7(A) and 7(B)show a second embodiment of the present invention. In the first embodiment, the folded part of each bypass4of the trunk line1is continuously folded without interruption. However, the second embodiment is the same as the first embodiment in that a coating of a wire W is stripped over a predetermined range of a folded part, but differs from the first embodiment in that a core7is cut in the folded part. In this second embodiment, cut end parts of the core7are connected by welding after cutting. Thereafter, a wire barrel6B-1of a trunk line terminal6is crimped to a welded part Y.

In the second embodiment configured as described above, the following effects are obtained. Since the folded part of the bypass4is continuous in the first embodiment, a reaction force upon bending is large, it is not easy to fold the wire W in a close contact state and connection to the wire barrel6B-1tends to be difficult. In that respect, if the wire is cut in the folded part and, thereafter, the cut end parts are welded as in this embodiment, the wire W can be easily folded in a close contact state as shown inFIGS. 7(A) and 7(B). Thus, connection to the wire barrel6B-1also becomes easier. Further, since the cut end parts are connected by welding, high contact reliability is also obtained.

The other configuration is as in the first embodiment and, hence, similar functions and effects can be exhibited.

The present invention is not limited to the above described and illustrated embodiments. For example, the following embodiments are also included in the technical scope of the present invention.

Although both the trunk line1and the branch lines2are formed of the twisted pair cables in the above embodiments, there is no limitation to this.

Although both the trunk line terminals6and the branch line terminals8are present in one connector CO in the above embodiments, these terminals may be accommodated in different connectors CO and connected as the both connectors CO are connected.

Although the folded part of the wire W is cut in the bypass4of the trunk line1and, thereafter, the cut end parts are welded in the above second embodiment, two cut end parts may be both directly fastened to the wire barrel6B-1of the trunk line terminal6without being welded.

LIST OF REFERENCE SIGNS