Design of power supply for automobile wiring harness

The car harness is the main body of the network of the car electric advance, and there is a car circuit without the harness. With the progress of people's requirements for safety, comfort, economy and emission of cars, the car harness becomes more and more complex, but the space for the harness is getting smaller and smaller. Therefore, how to improve the comprehensive performance planning of car harness becomes the focus of attention, and the manufacturers of car harness no longer simply do the later planning and production of the harness, and it is inevitable to develop the harness in the early stage with the car main engine manufacturers. Based on the experience of wiring harness planning and production in recent years, the author discusses the general planning process and planning principles of the harness.

Vehicle circuit planning

1.1 power distribution plan

Whether the power supply system planning of a car is reasonable or not is directly related to the normal operation of the electric equipment and the safety of the whole vehicle. Therefore, the starting point of the car harness planning in all countries is safety. The whole vehicle electrical system is basically composed of three parts.

a。 The load of the power supply of the battery direct power supply system (usually referred to as regular or 30 electricity) is generally the safety part or important part of the car. The primary purpose is to operate the parts as little as possible when providing power for these parts, so as to ensure that these parts can operate short and normal even if the car can not be started, so as to facilitate the repair at the station. For example: the working power supply of engine ECU and engine sensor, operation power supply of fuel pump, power supply of ABS controller, power supply of diagnosis interface, etc.

b。 The power supply system operated by the ignition switch (generally referred to as Ig gear or 15 power). This part of electrical equipment is basically used in the condition of engine operation. The power supply from generator avoids the possibility of competing for power supply when charging the battery. For example: instrument power, brake lamp power supply, airbag power supply, etc.

c. Remove the load power supply (generally referred to as ACC power supply) when the engine starts. This part of electrical equipment generally carries a large load, and does not need to work when the car starts. Generally there are cigarette lighter power, air conditioning power, power supply for the retractor, wiper power supply, etc.

12 line maintenance planning

The maintenance of the line is to maintain the conductor and to take into account the maintenance of the circuit electrical equipment. The maintenance device is mainly composed of fuse, circuit breaker and fusible wire.

12.1 selection principle of fuse

a。 ECU and ABS of engine have great influence on performance and safety of the device. For other electrical materials which are easy to be interfered by other electrical equipment, it is necessary to set fuse alone.

b。 The engine sensors, various alarm signal lamps, external lights, horns and other electrical equipment have a great impact on the performance and safety of the vehicle, but the electrical load is not sensitive to the interference wells between each other. So, this

The class electric load can be combined with each other according to the condition, and a fuse can be used together

c。 The electric load of general electrical materials set for adding comfort can be combined with each other according to the condition, and a fuse can be used together.

d。 Fuse is divided into fast melting type and slow melting type. The primary component of the fast-melt fuse is fine tin wire, among which the chip fuse is simple in structure, reliable and vibration resistant and easy to detect, so it is widely used; slow melting type

Fuse is actually tin alloy. Fuse of this structure is usually connected to inductive load circuit, such as motor circuit.

e。 The load of resistance type and inductive type shall avoid the same fuse as possible.

f。 Generally, it is calculated and calculated according to the maximum connected current of electrical equipment

Confirm the fuse pit quantity, according to the experience formula: additional cellar quantity of fuse = maximum operating current of circuit ÷ 80% (or 70%)

122 circuit breaker

The most important feature of circuit breaker is the recoverability, but its cost is higher and less used. Circuit breakers are generally thermal mechanical devices, which make contact open and close or self-closing by using different thermal deformation of two metals. The new circuit breaker, which uses PTC solid data as the over-current maintenance element, is a kind of resistance with positive temperature coefficient, which is disconnected or connected according to the current or temperature. The greatest advantage of this maintenance element

It can be automatically connected after troubleshooting, and it does not need manual adjustment and replacement.

1.23 fusible wire

The characteristics of fusible wire are that when the line passes through a great overload current, the fusible line can fuse in a certain time (generally ≤ 5S), thus cutting off the power supply and avoiding the occurrence of malignant accidents. Fusible wires are also made of conductors

And the green layer, the insulation layer is generally ar sulfonated polyethylene data because the insulation layer is thick, so it looks like the same specification of the wire is generally connected to the battery directly led out of the circuit. easy

The common common sections of the melting line are 0.3mm2, 0.5mm2, 0.75mm21.0mm2, 1.5mm2, and even larger fusible lines with 8mm2. The length of the wire segment of fusible wire is divided into (50 ± 5)

Mm, (100 ± 10) mm, (150 ± 15) mm3.

The fusible wire shall have obvious marks, and when it is blown, its mark shall still exist for replacement. The fusible characteristics of fusible wires are shown in Table 1.

Mall development

The global demand for distribution transformer Market in 2018 is about US $12.81 billion. With the continuous increase of power demand, it is estimated that by 2021, this data will increase to US $17.61 billion, with a compound annual growth rate of about 6.57%.

From the heat insulation type, the liquid immersed transformer in 2018 will be the most demanding distribution transformer. It is widely used in the fields of power, industry and Commerce due to its high energy efficiency, low noise and long life. Together, this type of transformer is manufactured according to the most stringent industrial standards and international standards, and can be used in indoor and outdoor environment.

From the type of device, box transformer is expected to be the most demanding distribution transformer. The continuous development of renewable energy will greatly promote the addition of box transformer demand.

From the regional perspective, Asia Pacific region will become the largest regional shopping mall for distribution transformers in the world, mainly due to the regional transmission and distribution infrastructure, increased industrial investment and aging distribution equipment replacement.

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