The wire harness is a thing with a multi-core connector that can connect multiple electric wires at the same time by putting together a plurality of electric wires by a binding band, a tube, an adhesive tape and the like, even in the case of having a hook or the like fixed to a machine to be incorporated. Compared to a bundle of wires not compiled, not only can the assembly process of the machine be simplified, but also the space occupied by the bundle of electric wires can be reduced, and rubbing due to vibration can be reduced. By using flame-retardant materials for wire covering and protective equipment, the risk of fire spreading in case of fire can be reduced.

wire harness component parts

Electric wire

The electric wires to be used are required to have necessary electrical characteristics such as current and frequency characteristics, and it is necessary to minimize the risk of electromagnetic leakage to the surroundings and short-circuiting to the wires and the surroundings. Generally, a plurality of strands made of a copper alloy is covered with an insulator having high wear resistance. Polyvinyl chloride has been used for such wire coating material for a long time but in recent years it has become more environmentally friendly to use halogen-free coatings.

The thickness of the electric wire is determined with respect to the energizing current and the applied voltage. Besides the structure of the general structure, the element wire configuration has a configuration that is excellent in bending durability performance. For high-temperature parts such as engine room, use a coating excellent in heat resistance. Shields are generally applied to lines that are susceptible to external noise such as weak current circuits. Wire color is often determined mainly by the productivity of the manufacturer. In grounded circuits, black stripes are mainstream on white background.

In addition, as the number of necessary signal lines increases in accordance with an increase in mounted electronic devices such as automobiles and aircraft if multiplexed signals based on digital signals are sent by a small number of optical fiber lines, Of the electric wire tends to be less. Fiber optic wires may be wired separately from wires or fiber optic wires as well as electric wires may be included in the wire harness.


It is a connecting part at both ends of each electric wire to transmit electricity to an appropriate circuit and fix it at the same time. Like electrical wires, appropriate electrical characteristics and safety can be obtained. The connector has a connecting terminal inside the housing and has a shape that does not erroneously connect signals and electric power at the time of assembly and can be easily connected and can not easily be disconnected by vibrations etc. after connection and can be connected stably for a long time It is maintained and it is required to be easily removed as necessary for repair etc. In the connector, the connection terminal is first attached to the electric wire, and then the connection terminal is generally housed in the housing.

Forming / Protective Equipment

Bundle the trunk wire which is the bundle of main wires by a corrugated tube, resin tape or the like, and protect it with a protector etc. In the branch where the individual electric wires branch off from the mains electric wire, it is fixed with a thermoplastic resin or the like in order to keep the bundle.


Fasteners such as grommets, clamps, and clips are often incorporated to fix them to the housing. Fixtures and protective equipment may double as each other.


In addition to wires that make only one-to-one connections, there are cases in which it is desirable to connect terminals of three or more devices with electric wires. In a wire harness that bundles a large number of electric wires, an intermediate connection portion is provided in the wire harness, and a plurality of electric wires There is a junction box (JB) that connects each other with a junction box. In order to connect electric wires to each other, the junction box houses electric wires, printed boards, bus bars and the like in the connection terminals inside, and some of them contain fuses, relays and circuit breakers. Those including electronic circuits such as semiconductor elements are called A-JB (Active Junction Box).