2023 Author: Erin Ralphs | [email protected]. Last modified: 2023-05-20 18:31
What is a VAZ 2108 generator and where is it installed, every owner of this car knows. But it is unlikely that everyone will be able to say on what principles it works, as well as list all the main elements of which it consists. It is worth noting that a generator and a simple DC motor are very similar in design. They are not even just similar, but are identical devices. The only difference is that one generates electricity, and the other consumes. But the differences don't end there, you need to look in more detail at the generator system to find them all.
Rotor and its winding
It can be said that the basis of the generator is its rotor. It has a copper wire winding. The rotor winding is supplied with a constant voltage from the battery. The principle of operation of any generator set is that it is necessary to have two main components - movement and a constant magnetic field. How can the latter be created? Either by installing powerful magnets, or by winding a wire on a magnetic circuit. The first option disappears immediately, since the cost, for example, of neodymiummagnets, which are ideal for this purpose, are too high. The VAZ 2108 generator circuit includes a winding on the rotor.
It turns out to be much cheaper and easier to wind a copper cable on the magnetic core. The thing is that when voltage is applied to such a winding, a magnetic field is generated. And it is the greater, the higher the field strength. Consequently, with an increase in the characteristics of the supply voltage, the field also increases. It is worth noting that copper wire is many times cheaper than neodymium magnets, and its service life is very high. It is almost impossible to cause electrical damage to it, as well as mechanical ones. The latter - except for careless handling during repairs.
The VAZ 2108 generator has a rather massive stator winding, as it uses a large cross-section wire. It is with its help that electricity is generated. The wire is wound evenly over the entire inner surface of the stator into recesses in the magnetic circuit specially provided for this purpose. Separately, it is worth talking about the latter. The middle part, the generator stator, consists of a set of thin metal plates pressed tightly against each other. Often, they are boiled on the outside so that delamination does not occur.
In fact, of course, the stator winding of a car generator consists of three absolutely equal parts. The reason is a special way of generating electricity - it requires a three-phase alternating voltage, which subsequentlywill straighten up. But this process will be discussed below. In other words, the stator of a car generator is very similar to a similar element of an induction motor. Even the connection of the windings is made according to such an exact scheme. The connection of the VAZ 2108 generator, or more precisely, its windings, is made according to the “star” scheme.
Caps and bearings
There are bearings in the front and back covers, which are attached to the stator housing. They are necessary to ensure the normal functioning of the generator. With their help, the rotor rotates more freely, but most importantly, it is centered strictly along the axis of rotation. Therefore, the rotor magnetic circuit does not touch the stator winding during operation. Lids are made of light metal - aluminum, which performs several functions at once.
First of all, aluminum absorbs and releases heat very well. And the VAZ 2108 generator heats up very much during operation. Secondly, aluminum is lightweight, which makes the entire structure lighter. In addition, an impeller is mounted on the generator, in front of it. During the rotation of the rotor, it generates a stream of air that enters the body of the mechanism. This results in additional cooling.
A VAZ 2108 alternator belt is used to drive. It is worth noting that this car model was produced only with a carburetor injection system, so a wedge-shaped belt was installed on it. On newercars of the ninth and tenth families, which have an injection type fuel system, put a slightly different belt. It looks more like the one that drives the timing mechanism, only instead of teeth on the inside it has streams.
It is with the help of this device that the AC voltage is converted to DC. After all, you know that there is a plus and a minus in the on-board network of a car. And some may even say that the VAZ 2108 generator produces 12 volts. True, there will immediately be someone who can clarify a little, mentioning that on some cars there are 24 volts in the on-board network. But on eights, of course, only 12, this is quite enough. So, there are plus and minus in the on-board network, and there are three phases at the output of the generator winding. What to do?
For this purpose, a rectifier unit is used. It consists of three pairs of semiconductor diodes. It turns out that two diodes rectify each phase coming from the stator winding. And at the output of this device, after the conversion, a constant voltage is obtained. Also, the VAZ 2108 generator circuit includes a capacitor that cuts off all alternating current remaining after the rectifier unit. But the trouble is different - depending on the rotational speed of the rotor, the output voltage also changes. How to get rid of it?
The problem has been set, it needs to be solved. And this is not difficult to do if you simply stabilize the voltage that feeds the generator rotor winding. The thing is that now, no matter what voltage will be at the output of a pair of power sources - a generator and a battery, only stable voltage is supplied to the excitation winding (rotor). On VAZ 2108 cars, the generator voltage is about 12.5-13.8 Volts. Therefore, the magnetic field will always be the same, regardless of the speed of the rotor. And if so, then the voltage on the stator winding will also be stable.
How to dismantle the generator
To replace the VAZ 2108 generator as quickly as possible, you will need a penetrating lubricant. The reason for its need lies in the lowest mount. The bolt is located at the level of the engine sump. Unfortunately, the machine does not always have a mudguard. And even if it is, then moisture and dust get on the threaded connection. Therefore, it must be plentifully treated with a penetrating lubricant, and then allowed to stand for at least half an hour. This time is enough to soak all the rust and dirt on the threads.
If the generator has not been removed for a long time, then it is better to process the upper nut with the same lubricant. After such a small preparation, unscrew the nut from the top stud completely. Unscrew the bottom bolt using a ring and socket wrench. It is advisable to carry out this work from the bottom of the car, it will be much more convenient. It is possible that the bolt will start to come out tight. In order to pull it out, you will need to use a bolt or stud a littlesmaller diameter. Note that all this work must be carried out with the battery disconnected. All wires that connected the VAZ 2108 generator also need to be disconnected.
How to install a new generator
Installing a new generator is done in reverse order. Take a close look at the condition of the bottom bolt. If it has thread damage, it is better to replace it. It will also be easier for you to repair the generator later. Pay special attention to belt tension during installation. If it is not tight enough, then your battery will not charge well. And if you tighten the belt too much, then the bearing in the front cover will be destroyed. As a result, you will get an unpleasant whistle when the engine is running. And the reason for this is the appearance of backlash in the bearing. The installation of the generator on the VAZ 2108 should be done in such a way that even the slightest distortion does not occur.
In conclusion, I would like to note that only timely maintenance will ensure the normal and stable operation of the generator set. It is necessary to replace the voltage regulator, which is combined into one unit with brushes on eights, on time. You should not wait for the moment when the power to the rotor winding is lost due to the complete destruction of the brushes. Only under these conditions, the VAZ 2108 generator will not fail and will always give a normal charge for the battery.