Now the car configuration is getting higher and higher, the use of electrical appliances is gradually increasing, and the output capacity of the generator is becoming stronger and stronger. Most of the generators with brush generation 4 regulators are used on the vehicle, and the loading market is basically occupied by Beijing’s petrai and OBO. Let’s introduce the causes of generator failure and solutions.
The common faults of generator include abnormal noise of bearing, falling off of carbon brush, easy burning of regulator, etc. The concept of truck drivers in China is still somewhat backward. Almost no truck driver has a spare motor and generator on the car.
In case the generator bearing makes a noise at high speed, the disposal method at this time is to close the accelerator immediately and swing to the repair department at the lowest speed as possible. At the same time, there is a means to extend the distance, that is, turn off those less important electrical appliances, such as CDs and cooking tools. Although the generator can generate electricity normally, the coil magnetic field of the generator should be strengthened for each additional watt of electric energy. The resistance of this magnetic field should be applied to the bearing, and the bearing load is greater.
Of course, if the configuration allows, The generator belt can be removed directly (it seems that the current car road is impassable). If you drive during the day and the high-speed exit is not far away, you can stop in the service area, turn up the front of the car, remove all the wires on the generator, and then ignite. Since there is no external power supply to help the generator establish an electromotive force, the load consumption is close to 0, and the wandering distance can be longer.
After the carbon brush is polished, the carbon brush of the generator will be polished generally at about 120000-180000 km. The symptom is that during driving, the voltmeter drops to the battery voltage, the ignition is off, the key is turned on, and the charging indicator light is not on. After the carbon brush is polished, the magnetic field of the rotor cannot be established, and the generator will not generate electricity.
The emergency method is to stop the rollover head, find a small hammer and gently tap the rear end cover of the generator. Sometimes the spring is ejected due to vibration and the carbon brush contacts again, but you can’t last long just by this. During the maintenance process, the engine speed should be as low as possible and the unnecessary electrical appliances on the vehicle should be turned off, This can reduce the degree of spark ablation of the collector ring.
The generation voltage is high. During driving, the voltmeter rises to within 29.8v. I believe most electricians and drivers think that the regulator is burned. In fact, it is not. It can be seen from the schematic diagram of the generator. This is the principle of Y-shaped winding. Most of the windings on the car are in this form. In the picture, there are 8 silicon rectifier diodes and 3 excitation diodes (3 in the middle to the right).
The reason why the generation voltage rises to less than 30V: one of the excitation diodes breaks down, the three output terminals of the stator winding are w on the generator, and the series 1N5408 diode becomes D +. If one breaks down, the voltage of the other two groups flows back to one of them, resulting in the increase of magnetic field strength and the natural rise of generation voltage, which is not the damage of the regulator.
The maintenance of this fault is also very simple. Dismantle the development motor and replace a diode with a soldering iron. The cost is between 1 Mao and 3 Mao. If the voltmeter explodes, the regulator may be damaged, but now the regulator of vehicle generator has developed to the fourth generation, which will stabilize the maximum voltage at 28.8v.
The regulator is often burned out, sometimes one in a few days. This is because one or more groups of stator coils are short circuited. The short circuit is that the current does not flow enough turns. After taking a shortcut, the magnetic field of one group becomes stronger than that of other windings, and it is difficult for the regulator to stabilize. Burning is inevitable. In fact, people who understand it can understand the mystery from the schematic diagram.
The transmission ratio of vehicle generator is generally required to be 2.5-3.1. When the idle speed is 600 rpm, the generator speed is about 1500. Because the vehicle generator is an excitation alternator, It must reach a certain speed to generate electricity (permanent magnet generator is not the case). Most models need 1250 rpm, and some models are higher. The output capacity, temperature and horsepower of the generator are the same as those of the truck. For example, the water temperature must be high when the truck is loaded with 30 tons. If the throttle is increased, the water temperature will be lower than the low speed. Why?
First: the heat dissipation of the generator depends entirely on the internal or front fan blade. The higher the speed, the higher the air flow in the generator and the lower the temperature.
Second: the current output of the generator changes with the speed. For example, 1500 rpm, 70A, petley or OBO can output 32A current, and the power is about 900W. That is the speed at which the generator can only provide so much energy. 460 HP idling at 600 rpm certainly can’t output 460 HP? If the power consumption at this time is greater than 900W and the generator runs for a long time, there is no doubt that the generator will burn, but the process is relatively long and you don’t feel it.
Now the car is slowly changing to low speed and high torque, and the transmission ratio is gradually changing from the previous 2.5 to 3. Xichai and heavy truck are close to 3, that is, let the generator turn faster. In a word, ultra-low speed is waiting for the generator to burn down or decline.
Many drivers and even electricians think that my car has high horsepower and my inertia is enough for you to generate electricity. What does it have to do with fuel consumption? Hearing this, I think I’m drunk.
1： Where does your machine inertia come from? Can it produce inertia without basic diesel? You run on a flat road, and then you can slide for a distance when you put it in neutral. Then I want to ask, you don’t want to ignite. You let the car slide for hundreds of meters on a flat road. If you don’t agree, you can don’t refuel, and then ignite. I’ll see where the inertia of your machine comes from? This theory can not stand deduction at all. To say that it is pure is to deceive yourself and others.
2： The law of conservation of energy. I have read little and don’t understand the meaning of this sentence, but I understand that the extra watt of electric energy consumed by the car must be supplemented by other energy. Does it make sense for a person to work without eating? At most, the conversion rate and utilization rate of energy are different, which is called (energy efficiency ratio) in the household appliance industry.
Let me give you a simple example. When you drive a car, the water temperature reaches a certain level, and the electronic fan starts to power on, you suddenly feel that the headlights are dimmed, the machine speed is also reduced a little, and the strength is also changed. Why? Because the electronic fan consumes electric energy, the generator needs to supplement the energy, increase the load to the machine, and finally evolve into oil consumption.
Careful drivers will find that when they follow the bus or bus, why does a belt start to slip when they step on the brake in the engine compartment? This is because the eddy current retarder works, the generator load increases sharply, and the belt can’t exert so much torque, resulting in slip. What if you have more horsepower? Does the bus have less horsepower than your truck?
Sometimes the cars in the same industry run out of electricity and the motor can’t rotate. Some drivers take a wire to connect the batteries of the two cars and start the car. Let another car without electricity ignite. After lighting the fire, I found that the car running in advance suddenly didn’t generate electricity? The reason is that the starting current of the motor is very large, and the heavy truck is about 600-1200a. Your generator can only provide 70A power at most, and it needs more than 4000 revolutions. As soon as there was ignition, the generator regulator detected a sudden increase in discharge, and applied a higher frequency current excitation to the rotor. As a result, it exceeded the output capacity of the regulator, generated a lot of heat and burned.
If the ignition time lasts a little longer, the stator will decline. Even if it is not burned, the generation voltage and current can not be compared with before. This process only takes 1-2 seconds. Unexpectedly, it is a little similar to CPU overclocking. I also found that some drivers in the South have modified the independent diesel engine air conditioner, and there is a generator on it to directly start the cart when generating power. I can only say that if you start the cart before taking measures, you are lucky that the generator does not burn, and it is reasonable to burn it.
The car is becoming more and more different from the past. In the past, the car basically started and left when it needed power. In recent years, with the progress of technology, the vehicle is equipped with more electrical equipment, and the small generator is becoming more and more important. If you don’t pay attention, the car will stop on the roadside, and learn emergency measures to reduce your troubles.
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