Welcome to number one hundred big fat Carry a hoe, as Car enthusiasts today to tell you a little about the basics of Car maintenance electrician. Today to introduce the basics of Car maintenance electrician!
5. The Automotive electrical equipment characterIstics
(1) low voltage power supply. Rated voltage Automotive electrical equipment system has 12V and 24V constant. At present gasoline engines commonly used in 12V, while the diesel engine Is to use more 24V. (2) a DC power supply. One of the power supply Is on the Car battery, a DC power supply, a DC series motor, must be powered by a battery, it must be charged with the direct current and the battery dIscharge. While DC Is easy to store, so the use of direct current on the Car. (3) one-way system. Electrical equipment connected to the power supply circuit needs to be formed by two wires in order, to a phase line, a neutral line of the other. All electrical equipment on the vehicle are parallel, in theory there Is a need for a common phase and a common neutral line.
to the Car chassIs and engines are made of a metal having good conductivity, which may be used as a common neutral line. Power to electrical equipment can just use a wire connection, it Is called one-way system. Since the single-wire line with less guidance and clear lines, easy installation, and therefore widely used in modern Cars. (4) negative grounding. When the single-wire system, a battery must be connected to the electrodes on the frame, called Ground. If the battery Is connected to the negative electrode, said negative electrode on the grounding frame, otherwIse known as the positive electrode to ground. Ground frame or body of the negative electrode of a lighter chemical corruption, one thousand radio interference Is small.
6-bIs battery Automotive electrical system
with double batteries (starting type battery and powered battery) of in the form of Automotive electrical system batteries it Is to function, i.e., the starting process provides a high power and a separate electric power supply to the Automotive two functions, to avoid starting the process of polymerization Automotive electrical system voltage drop of the battery power supply and ensure that even in a low state of charge under cold start can be safely. At present, some high-class Cars, the use of dual-battery vehicle electrical system. Volkswagen Phaeton Car battery Car electric system using double the original workLi, shown in Figure 1-3. Under normal circumstances, the battery provides power for starting an engine starting circuit. On-board electrical system battery voltage of 12V to provide onboard power supply. During a cold start, the auxiliary starter batteries. And a switching control circuit of the starter circuit of the vehicle electrical system Is done by the battery monitor system control unit (J367). It controls the start and reliably guarantee the charging of the battery associated with the normal use of electrical equipment start.
7 starter-type battery
starting type battery must supply a large current for a limited time starting process. Because of the small volume of starting type battery, it can be close to the starter, and connected by a short cable to the starter. Starting type battery capacity also be small.
8. The battery-powered
Is a battery-powered starter other except Automotive electrical power supply system power device. It only provides a small current (such as the engine management system, about 2OA), but using very long period, that Is able to provide a large electric power energy storage and again at a certain depth of dIscharge capacity and reliability. Power supply type of battery parameters depends mainly on the capacity of electrical equipment access (such as parking lights, lights), the quiescent current and electrical equipment may be allowable depth of dIscharge (1) 14 / 42V dual voltage electrical system. The first step uses a high voltage vehicle electrical system Is to use a dual voltage 14V and 42V electrical systems of Automobiles. The advantage Is that the exIsting low-cost device can continue to use the electric 14V. The generator power directly to the electrical equipment of power 42V.
The rest of the electrical equipment by DC to DC (DC / DC) converter to a 14V electrical system. Selecting two parameters of the two-part battery electrical system enables them combined together well, the joint Will not harder than two battery currently in use work. When the generator Is designed as a single voltage (42V) output, and a power supply system using 14 / 42V dual voltage between high and low power supply between the low-pressure and high-power load must install DC / DC converter, power may be points systemCut two subsystems having different power supply voltages, shown in Figure 1-4. It uses a set of insulating widely] bipolar transIstor to operate in pulse width modulation to change the average of the output voltage by adjusting the duty cycle of the square wave voltage, to be the ideal voltage.
(2) 42V single-voltage electrical system. Single 42V electrical system voltage with high efficiency, relatively simple control system with a set of batteries with the same battery voltage and other characterIstics, the core Is an integrated starter – alternator system, referred to as the ISA. The system combines the power generated by the alternator and starter supply of two-in-one, you can achieve a more robust power supply and has a good start – stop characterIstics, and therefore has better fuel economy and lower emIssions. The system may also be effective at low engine speed in speed, and the torque ripple can be significantly buffered engine.
the next Issue we Will continue to analyze teach the fundamentals of vehicle maintenance electrician!
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