Metal Materials of Vehicle Wire Harness

The function of electric wire is expanded from ordinary signal transmission to data transmission. Due to the limitation of wire transmission signal, it is increasingly hindering the development of the whole vehicle. Therefore, the extensive use of optical fiber cable will usher in the third leap in automotive Wiring Harness's manufacturing technology. Optical fiber cable has the advantages of fast transmission speed, large capacity, small volume, strong confidentiality and good anti-interference, and will soon become an important preferred material for automobile data processing and exchange in the future, so that the power and signal distribution system will enter a new historical stage of development.

I. Metal Materials for automotive wiring harness Cable

Automotive wiring harness refers to a component which is formed by pressing the contact terminals (connectors) made of copper with wires and cables, and then molding an insulator or adding a metal shell on the outside, and binding them with wire harnesses to form a connecting circuit. Wire harnesses are widely used in automobiles, household appliances, computer and communication equipment, various electronic instruments and meters, etc.

Electric wires, also called low-voltage wires, are different from ordinary household wires. Ordinary household wires are copper single-core wires with a certain hardness. The automobile wires are all copper multi-core flexible wires, some of which are as thin as hair, and several or even dozens of soft copper wires are wrapped in plastic insulated tubes (PVC), which are soft but not easy to break.

The requirements of automotive wiring harness materials are very strict: including its electrical properties, material dispersion, temperature resistance, etc., which are higher than those of general wiring harnesses, especially those related to safety: wiring harnesses of important components such as direction control system and brakes are more stringent. The metal materials used for automotive wiring harness cables are as follows:

Copper: electrical conductivity is second only to silver, thermal conductivity is second only to gold and silver; Corrosion resistance, non-magnetism, good plasticity, easy welding and wide application. Copper alloy is mainly used to improve the wear resistance, corrosion resistance and mechanical and physical properties of copper.

Silver: Metal has the highest electrical and thermal conductivity, good corrosion resistance and oxidation resistance, and is easy to weld; Mainly used for coating and cladding; Mainly used as high-temperature resistant wire and (note: according to the principle of skin effect) as conductor of high-frequency communication cable.

Aluminum: conductivity is second only to silver, copper and gold; Good thermal conductivity, good corrosion resistance, average mechanical strength, good plasticity and small specific gravity. The disadvantage is low tensile strength and difficult welding. Aluminum alloy is mainly used to improve the mechanical strength, heat resistance and weldability of aluminum.

Gold and nickel: used as high-temperature resistant wires.

Iron (steel): It is often used as a reinforcing material for composite conductors, such as steel-reinforced aluminum stranded wire, copper-clad steel, aluminum-clad steel wire, etc.

Zinc: used as the coating of steel wire/steel strip/iron conductor to prevent corrosion.

Tin: used as the coating of steel wire/copper wire to prevent corrosion and facilitate the welding of copper wire.

II. Types, specifications and standards of cables and wires in automotive wiring harness

Automotive wiring harness cable is widely used in automobiles. What kind of conductor type to choose for automotive wiring harness cable plays an important role in the performance of automotive wiring harness. To design a good Wire Harness, we should not be careless in choosing the type of wire. Wires can be divided into electronic wires and cable wires according to their nature: electronic wires include unshielded wires and shielded wires (UL1571 wires will have shielded wires, while other electronic wires are generally unshielded wires); Cable also includes unshielded wire and shielded wire, such as UL2464, which can be divided into these two types. According to the standard points: UL/CSA (safety line), CCC (national standard line), VDE (German marking line), PSE (daily marking line), etc. Among them, UL/CSA, VDE and CCC are common lines, and UL/CSA lines are the most commonly used at present.

The common specifications of wires in automotive wiring harness are square millimeter wires with nominal cross-sectional areas of 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, 4.0, 6.0, etc. They all have allowable load current values, which are suitable for wires of different power electrical equipment. Take the whole vehicle harness as an example, the 0.5 gauge line is suitable for instrument lights, indicator lights, door lights, ceiling lights, etc. 0.75 specification line is applicable to license plate lights, front and rear small lights, brake lights, etc. 1.0 specification line is applicable to turn signals, fog lights, etc. 1.5 specification line is applicable to headlights, horns, etc. Main power lines, such as generator armature line and grounding line, require 2.5 ~ 4 mm wires. It's just that for ordinary cars, the key depends on the maximum current value of the load, such as the grounding wire of the battery, while the positive power cord is a special car wire used alone. Their wire diameters are relatively large, at least more than ten square millimeters, so these "Big Mac" wires will not be incorporated into the main wiring harness.

The types of conductors commonly used in automotive wiring harness are Japanese Standard (AVSS, etc.), National Standard (QVR), German Standard (FLRY), American Standard, etc. AVSS conductor is characterized by thin skin insulation and good flexibility; QVR is characterized by thick insulation, softness and good ductility; German standard conductor has thinner insulation and good flexibility; American standard wire insulation sheath is generally thermoplastic or thermosetting elastomer, and some are processed by irradiation process. According to the user's needs and different working environments, the appropriate type of conductor can be selected. The wires commonly used in automotive wiring harness usually use stranded copper wires with PVC insulation.

Wire harness should be heat-resistant, oil-resistant, wear-resistant, waterproof, anti-corrosive, anti-oxidation and flame retardant. When selecting wires for automotive wiring harness, the environment and functions of wiring harness should be fully considered. For example, the ambient temperature around the engine is high, and there are many corrosive gases and liquids. Therefore, be sure to use high temperature, oil, vibration and friction resistant wires; The wires on the luggage compartment cover should keep their elasticity at low temperature, so cold elastic wires should be selected to ensure their normal work; The wire on the automatic transmission must be resistant to high temperature and hydraulic oil, and its temperature stability is good; Weak signal sensors should use shielded wires, such as knock sensor, crankshaft position sensor, ABS wheel speed sensor, etc. The door inner line has high requirements for bending resistance.

III. Technical Requirements for Cross Section of Automobile Low-voltage Wire Harness

Automotive wiring harness is one of the products with fast development, the largest market demand and convenient installation in today's electronic and information age. The interior configuration of the car is complete, but the electrical circuit hidden inside the car body is complex, the size is too large, and it is not easy to replace. The reliability of wire harness is the key component that affects the performance of the whole vehicle, so it is necessary to control the quality of wire harness.

Crimping should be preferred to connect terminals with wires. The connection shall meet the following requirements: the terminal shall be pressed on the conductor and the insulation layer respectively, the conductor shall not be broken, the insulation layer shall not be pressed into the conductor crimping part, and the automotive wiring harness section of the wire conductor shall be visible, but it shall not hinder the plug-in. The cross-section of the terminal and wire crimped by crimping method shall meet the requirements of the specification. Connector metallographic analysis system.

According to the relevant national technical specifications, wires with different circuits, wires with different voltages, different AC wires and DC wires cannot be worn in the same protective tube. Because different lines have different uses and specifications, the electric loads are also different. If they are worn together, the lines with larger electric loads will interfere with and damage the lines with smaller electric charges. If the power cord is blown, it will cause short circuit, spark and fire. The weak signal line can't go together with the strong one, because the electromagnetic field generated by the strong one will affect the weak signal and affect the communication and video effects. The cross-sectional areas of lighting wires and socket wires are different, and the load power is not uniform. Frequent use of socket wires will cause electric shock and short circuit. Therefore, wires with different purposes and functions must not be worn in the same protective tube.

IV. Arrangement and processing of cables and wires in automotive wiring harness

Before arranging the wiring harness, draw the wiring harness diagram in advance, which is different from the circuit schematic diagram. The circuit diagram is an image that expresses the relationship between various electrical parts. It does not reflect how the electrical parts are connected to each other, and is not affected by the size and shape of each electrical component and the distance between them. The wiring diagram must take into account the size and shape of each electrical component and the distance between them, and also reflect how the electrical components are connected with each other. After we, Kable-X, made the wiring harness wiring board according to the wiring harness diagram, it cut off the wires and arranged them according to the regulations of the wiring board.

The main wiring harness of the whole vehicle is generally divided into engine (ignition, EFI, power generation, starting), instrument, lighting, air conditioning, auxiliary appliances and other parts, including main wiring harness and branch wiring harness. A vehicle main harness has multiple branch harnesses, just like tree poles and branches. The main wiring harness of the whole vehicle often takes the instrument panel as the core part and extends back and forth. Due to the length relationship or convenient assembly, some car harnesses are divided into front harness (including instrument, engine, front light assembly, air conditioner, battery), rear harness (tail light assembly, license plate light, trunk light), roof harness (door, dome light, sound horn), etc.

Each end of the wire harness will be marked with a logo number and letter to indicate the connection object of the wire. The operator can see that the logo can be correctly connected to the corresponding wires and electrical devices, which is especially useful when replacing the wire harness. At the same time, the color of the wire is divided into single-color wire and double-color wire, and the purpose of the color is also specified, which is generally the standard set by the factory. China's industry standards only stipulate the main color, for example, it is stipulated that single black is dedicated to the ground wire, and red monochrome is used for the power cord, which cannot be confused. Harness is wrapped with woven thread or plastic adhesive tape. For safety, processing and maintenance convenience, woven thread wrapping has been eliminated, and now it is wrapped with adhesive plastic tape.

Harness is wrapped with woven thread or plastic adhesive tape. For safety, processing and maintenance convenience, woven thread wrapping has been eliminated, and now it is wrapped with adhesive plastic tape. Connectors or lugs are used for the connection between the harness and the electrical parts. Plug-ins are made of plastic and have plugs and sockets. It is connected with the wiring harness by a connector, and the wiring harness is connected with electrical parts by a connector or lug. With the increase of automobile functions and the widespread application of electronic control technology, there are more and more electrical parts and wires, and the wiring harness becomes thicker and heavier. Therefore, advanced cars have introduced CAN bus configuration and adopted multiplex transmission system.

Compared with the traditional wiring harness, the multiplex transmission device greatly reduces the number of wires and connectors, making wiring easier.

The conductor of automobile wire is twisted by many copper wires, and the twisted conductor has good bending and flexibility. The copper wire of the stranding body is drawn by drawing a thick copper rod with a wire drawing machine. The size of copper wire is about 0.1~0.4mm, which is similar to the thickness of hair wire. The traditional wire drawing machine can only draw one copper wire at a time. The copper wire drawn by a single-head wire drawing machine is drawn at different times and different equipment, and its technological conditions are very different. It is difficult to keep consistent with various technological parameters such as mold, lubrication, drawing force, tempering temperature and time. When such copper wires are put together, their size, material, metallographic structure, mechanical elastic modulus and ultimate elongation at break are very different. At present, the advanced wire drawing machine is a multi-head wire drawing machine with continuous annealing, which can draw a bunch of copper wires at a time, and there are more than a dozen copper wires in this bunch. This kind of wire drawing machine occupies less land, has high production efficiency, remarkable energy saving, few employees and low labor intensity. Multi-head wire drawing technology is widely used by foreign automobile wire manufacturers, mainly because it ensures the high quality of automobile wires.

V. Selection of cables and wires in automotive wiring harness

Generally, automotive wiring harness uses copper-core PVC (QVR) and copper-core PVC-Ding Qing composite insulated low-voltage wire (QFR) as materials, while PVC (OVR-105) with copper-core heat resistance of 105℃ is applied to the electrical and instrument circuits in high-temperature areas of vehicles.

Color of harness: the bus harness is intricate. For the convenience of wiring and repair, the thread ends should be visually distinguished, and the lines with the same diameter in the same bundle should be distinguished in color as far as possible. The color of the harness can be divided into monochrome or bicolor: bicolor is composed of main color and auxiliary color, and the auxiliary color is two axial straight bars, which are distributed symmetrically. The arrangement method is that the main color is first followed by the auxiliary color, such as red-green line (RG); The colors and codes of the monochrome signs are red R, orange O, yellow Y, green G, brown N, blue U, purple P, black B, white W and gray S.

Cable is the main carrier of power transmission. When purchasing automotive wiring harness cable, pay attention to the following points: When purchasing wire and cable products, you should observe whether the relevant information such as product model, specification, rated voltage, core number, production date, implementation standard, license number, etc. are marked completely in the product certificate, and the product surface should be printed with the continuity mark of the factory name, product model and rated voltage, so as to verify whether the two related information are consistent. The outer plastic skin of the wire is bright in color and fine in texture, whether there are burrs or protrusions on the surface, and whether the appearance is smooth, round and uniform in color. Electrolytic copper is used as the conductor, and the outer layer is bright and slightly soft. Look at the section of the cable again. The copper (aluminum) core should be in the middle, and the thickness of the plastic layer should be uniform. There are length marks on the certificate. You can first estimate the length of a circle of the finished package, then count the number of circles of the coil to estimate the approximate length of the whole winding. In addition, you should pay attention to the diameter of the conductor, and look at the length and cross section of the cable. When selecting wire and cable products, it is best to consult experienced professional electricians, and choose cables with appropriate cross-section size and voltage grade according to their own electricity load.

VI. Concluding remarks

To sum up, with the increase of automobile functions and the widespread application of electronic control technology, there are more and more electrical parts, more and more wires, and the wiring harness becomes thicker and heavier. Modern cars have introduced CAN bus configuration and adopted multiplex transmission system. Compared with the traditional wiring harness, the multiplex transmission device greatly reduces the number of wires and connectors, making wiring easier.