A car generator is one of the key elements of the technical stuffing of a car, the very possibility of driving a car directly depends on the serviceability and accuracy of its operation. When moving, it recharges the battery, and also generates energy that feeds various electrical equipment. It is important for the car owner to understand the design features and the principle of operation of the autogenerator, its possible malfunctions, as well as ways to check it - otherwise there is a risk of being left without a car at the most inopportune moment.

First of all, let's take a closer look at the functions of the car generator. All modern cars are equipped with an extensive list of electrical equipment that requires a power source. It is also needed for models that do not have any additional peripherals, electricity is required, at a minimum, to start the engine with a starter, create a spark on candles to ignite the air-fuel mixture, etc. To provide all these consumers in the car, 2 sources are used - a battery and a generator.

The battery stores energy and can give it to consuming devices when needed. While the generator produces energy, powers the devices and recharges the battery. Thus, if the generator is removed from the design of the car, it will be able to start and even drive for some time, however, after the battery charge is exhausted, the car will stall. It will not be possible to re-start it without “lighting it up” from another car.

Thus, the main functions of a car generator are:

• battery recharging;
• power supply of electrical equipment installed in the car.

The principle of operation of a car generator

By the nature of the work, the autogenerator resembles an ordinary electric motor, but the principle of its operation is diametrically opposite: if an ordinary motor converts energy into mechanical movement, then the generator, receiving a rotational impulse from the internal combustion engine, converts it into electricity.

The principle of operation of a car generator is approximately as follows. After turning the key in the ignition lock, voltage is supplied to the rotor winding, it passes through the slip rings and the brush block. As a result, a magnetic field develops around the winding. This field constantly rotates with the motor rotor, while interacting with the stator windings. A current appears on the stator winding, which is supplied to the diode bridge. At the output of the diode bridge, the current already has a stable value. Next, the current is supplied to the voltage regulator, after which it is used to power consumers and the battery.

An important element in the operation of a car generator is a voltage regulator relay. It is necessary to maintain the required current values ​​supplied to the battery. Without the use of a regulator, when the engine speed was increased, the generator would create excessive voltage, which could damage the battery. Also, this relay provides thermal compensation - at low temperatures, an increased voltage is applied to the battery, with an increase in operating temperatures, the voltage will decrease.

Signs of a malfunctioning generator

During the operation of the car in the generator, various problems can occur - mechanical or electrical. The first group includes wear and tear of device components, the second group includes various problems with the winding, brushes, failure of the voltage rectifier, relay regulator, etc.

In a timely manner, it is possible to identify an impending or already occurring breakdown of the generator by the following symptoms:

1. Difficulty starting the engine. If the generator is not operating normally, then the efficiency of recharging the battery is often disrupted. As a result, it receives an insufficient or excess charge, as a result of which it becomes very problematic to start the engine.
2. Dim or flashing light. If, when driving at night, it becomes noticeable that the headlights do not shine brightly enough or the strength of the light they create varies depending on the level of revolutions in the engine, then this indicates that the generator cannot provide the required amount of energy and voltage.
3. The "Battery" indicator on the dashboard lit up. This icon is always illuminated before starting the engine, after which it should turn off. However, if it stays on even when the engine is running, this indicates that the battery is not charging properly.
4. Noisy alternator belt drive. Many motorists have heard an unpleasant whistle coming from the engine while it has not yet warmed up. It may indicate a weak tension in the drive belt, which transmits rotation from the engine to the generator rotor. Operating the vehicle in this mode may result in reduced generator efficiency.
5. Ringing or unpleasant whistling from the generator housing. Such extraneous sounds indicate bearing wear. As a result, the rotor may begin to wedge.

How to test a car alternator

If it is still better to trust the repair of the generator to professionals, then the check can be performed independently. The first diagnostic method is using a multimeter:

1. We measure the voltage at the battery terminals with the engine off - it should be approximately 12.7V;
2. We start the engine without giving gas, turn off all electrical appliances (air conditioning, audio system, etc.);
3. We measure the battery voltage again - with the engine running, it should be from 13.8 to 14.5 V (on some engines up to 14.8 V);
4. We give the load - headlights, air conditioning, audio system, fog lights, etc .;
5. Again we measure the voltage - it should drop to 13.7-14 V. If the multimeter reading is lower, then this indicates a non-working generator.

You can also check the "old-fashioned" method. To do this, we start the engine, turn on a small load (for example, headlights) - and, without turning off the ignition, remove the negative terminal from the battery. If the engine does not stall, the lights do not go out, then this means that the generator provides the engine with enough energy. If the machine stalls after removing the terminal, then this indicates a non-working generator.

Related video

When it comes to powering a car with electrical energy, many car owners, for some reason, only remember the battery (battery), here, we read - how to choose a battery. But after all, the main detail, due to which the transformation of the energy coming from the engine, from mechanical to electrical, is the generator. It is he who feeds all the electrical equipment in the car (when running) and charges the battery.

The device of the automobile generator.

Consider what it consists of, as well as how this automotive unit works. True, I will immediately make a reservation that we will be talking about a car alternator, since it is this type of them that is installed on modern vehicles.

What is a generator made of?

The car generator, as a rule, has the following components:

1. a pulley is a kind of entry point (using a belt) for mechanical energy into the generator;
2. the body of the generator, which is formed by two covers, front and rear, almost all other components of the part we are considering are actually attached to them;
3. rotor - is attached to the front cover of the generator housing and consists of a steel shaft with 2 steel bushings (they are beak-shaped) and an excitation winding between them, to which, as a rule, copper cylindrical slip rings are attached;
4. stator - responsible for the power of the generator and consists of a metal core with 36 grooves and a winding;
5. rectifier shield - with the help of 6 powerful diodes (3 positive and 3 negative) it converts the voltage that the stator creates into the DC voltage of the car's on-board network;
6. voltage regulator - monitors that, i.e. regulates so that the voltage of the on-board network of the machine is always within the specified limits, regardless of the load, ambient temperature and rotor operation.

Diagram of a car generator.

The principle of operation of the generator.

This means that when the driver turns the key in the ignition, voltage is supplied to the winding (there is a magnetic field in it) in the rotor from the battery through the brush assembly. And as soon as the engine crankshaft begins to rotate, as you remember, thanks to the pulley, the generator rotor also begins to rotate. The magnetic field that is created in the latter starts the stator windings, thereby creating an alternating voltage at their terminals. At a certain speed, the generator stops being powered by mechanical energy and begins to create the voltage it needs on its own (the excitation winding is powered inside the generator).

The resulting voltage is sent to the rectifier board, where it is converted into direct current, which charges the battery and powers the car's electrical appliances.

Moreover, if the crankshaft changes its speed of rotation, then a voltage regulator is also included in this system. Depending on the external load, it regulates the turn-on time of the field winding: with a decrease in load and / or an increase in the speed of rotation of the crankshaft, the turn-on time of the field winding is reduced, and with an increase in load and / or a decrease in crankshaft speed, it increases. That is the job of a car generator. In addition, I recommend that you read two articles:

If we compare a car with a living organism, then its engine acts as a heart, and a generator acts as a nervous system. Will the car be able to move without this unit? Yes, it can, but not for long, not yet. It is the car alternator that charges the battery, maintaining the overall voltage of the working network. We will tell you about the principle of operation of the generator and its main elements.

How the unit is arranged

Rotor

This part, in fact, is an electromagnet with one winding. It is located on the shaft. A special core is attached over the winding, the diameter of which is one and a half to two millimeters less than the diameter of the starter. The current supply is provided by copper rings. They are also located on the shaft and are connected to the winding with special brushes.

Winding

The starter winding is made of copper wire. It is attached to the grooves of the core. The latter is made in the form of a circle and is made of metal with enhanced magnetic properties. This material is called transformer iron. Since the generator is three-phase, the starter is equipped with three windings. They are connected to each other and together resemble a triangle.

A rectifier bridge is connected at the point of their connection. The wire from which the winding is made is provided with double heat-resistant insulation. In most cases, a special varnish is used for this.

Relay-regulator

Another important element is the relay-regulator. It is an electronic circuit and has an output to graphite brushes. The relay-regulator can be installed in the generator housing or separately from it. In the first case, it is located next to the graphite brushes, and in the second, the brushes are attached to.

Rectifier bridge

The part is formed from six diodes. The latter are located on a conductive base in pairs and are combined with each other. At the output, the AC voltage is converted to DC. The bridge is also called a "horseshoe" due to the fact that outwardly it resembles this product.

On the video - the generator device:

The principle of operation of the generator

The operation of a car generator is based on the principle of education. This happens in the stator windings. Electric voltage is generated due to the influence of a constant magnetic field formed around the core. The motor drives the generator rotor by means of a belt drive. A constant voltage is applied to the winding, which is sufficient to create a magnetic flux.

When the core rotates along the windings, an electromotive force arises in them. The relay-regulator adjusts the strength of the magnetic flux in accordance with the load that is removed from the generator terminal. At the output, a voltage is formed in the range of 13.6–14.2 (this depends on the time of year). This is enough to recharge and keep it constantly charged. The on-board network is also powered by the positive terminal and is connected in parallel with the battery. Regardless of which generator you bought, the device and principle of operation will be the same for all samples. All such units work the same way.

On the video - the principle of operation of the generator:

Not a single car generator can work without. This element ensures that the constant voltage is maintained, which the unit generates due to the change in current strength that occurs in the windings. If the rotor rotates at a high frequency without a regulator, the voltage can reach a couple of tens of volts. This will lead to burnout of lamps and breakage of windings, diodes and other devices.

Regulator types

According to their design, voltage regulators are divided into two main categories:

• hybrid;
• integral.

The first group includes regulators, in the electronic circuit of which radio elements and are simultaneously used. In modern car models, integral regulators are most often used. All components of such devices (with the exception of the output stage) are made on the basis of thin-film microelectronic technology.

Pilot lamp

In order to avoid problems with the regulator, keep an eye on the control lamp. It is located on the dashboard of the car. If the lamp is on when the generator is running, this indicates a malfunction of the voltage regulator or the unit itself.

Car alternator mount

The car generator is usually attached to the front of the engine with bolts and special brackets. Mounting paws and an eye of the device are located on the covers. If the generator is attached with two legs, they are located on two engine covers. If only one mounting foot is used, it is placed on only one cover (front). The rear leg usually has a hole in which the spacer is installed. It eliminates the gap formed between the motor bracket and the foot base.

Different operating modes of the generator set

In order to understand the car generator, you need to understand the modes of its operation. The first mode that we will consider is the operation of the car generator during engine start. When starting the engine, the starter is mainly consumed by electricity. In this mode, the current strength is very large, and this causes a significant decrease in the voltage at the battery terminal. Thus, consumers of electricity are powered only by the battery, which is intensively discharged.

Immediately after starting the engine, the generator becomes the main source of power. The device provides the current needed to charge the battery and operate various electrical appliances. After , the charging current level drops. The generator remains the source of electricity.

When powerful consumers of electricity, such as headlight heaters or stove fans, are turned on, the rotor begins to rotate slowly. Then the generator can not give as much current as required. In this mode, the load is transferred to the battery, which is quickly discharged.

You can replace the generator in the car, but for this you must follow some rules:

• the new unit must have the same current-speed characteristics as the standard one;
• the energy parameters of the generators must be the same;
• the dimensions of the new generator must be suitable so that it can be easily installed on the motor;
• the units must have the same gear ratios;
• the circuits of both generators must be completely identical.

Keep in mind that, in general, units installed on foreign cars are attached with only one paw. At the same time, domestic devices using two paws. Therefore, when changing a foreign unit to ours, you will have to replace the mounting bracket on the motor.

When installing the battery in a car, you need to make sure that the polarity is connected correctly. In the event of an error, the alternator rectifier will fail, and this may lead to a fire. The same danger is fraught with starting the motor with incorrect polarity determination.

During the operation of the machine, the following rules must be observed:

• control, monitor the cleanliness of the contacts and the reliability of their connection (if the wire contacts are bad, the on-board voltage is out of range);
• disconnect the wires from the car generator and battery during electric welding of structural elements;
• make sure that the alternator belt is correctly tensioned (if it is loosely tensioned, the generator will not be able to work efficiently, if it is too tight, its bearings will wear out quickly);
• in case of signaling by a control lamp - immediately find out the reason for this.

On the video - generator repair:

Under no circumstances should you do the following:

• leave the car with the battery connected if you suspect that the rectifier is defective (this will lead to battery discharge and wiring fire);
• check whether the generator is working by closing its outputs to each other or disconnecting the battery when the engine is running (due to this, the voltage regulator, on-board computer, electronic elements of the ignition system may break);
• to allow the ingress of residues of antifreeze or other liquid on the generator;
• leave the generator on if the battery terminals are removed (this leads to damage to the electrical equipment of the machine and the voltage regulator).

We told you about the main features of the generator. This knowledge will be useful to any driver who seeks to understand cars. Remember that the generator is a very complex device, so it is important to take good care of it. Constantly monitor the condition of all its parts, as well as the degree of tension of the drive belt. Then the car generator will be able to serve you as long as possible.

Please leave your comment about what you read! We are interested in your opinion.

Two current sources are provided to power the on-board network of the vehicle. And it is very important for the driver to understand the principles of operation of the car generator, which, along with the battery, is designed to provide energy to the electrical equipment of the car.

Strict requirements are imposed on the reliability and stability of devices of this kind.

In the Russian Federation, electrical equipment manufactured and used must comply with GOST R 52230-2004. The document establishes general technical conditions that apply to car starter batteries. The mentioned national standard fully complies with international standards, which allows the use of foreign-made components on domestic machines.

At the dawn of the automotive industry and up to the 60s of the last century, direct current generators were used in on-board networks - capricious and low-power. With the advent of semiconductor (selenium and silicon) rectifiers, AC units began to be installed on machines. They are three times smaller in weight and at the same load provide a higher stability of the output current.

Why does a car need a generator?

The generator is used to maintain a certain voltage and current in the on-board network. The main purpose of a car generator is to provide a stable power supply to electrical equipment when the engine is running - in particular, for:

• Battery charge.
• Supply of all consumers of electric current under normal conditions.
• Power supply of consumers together with the battery during extreme operation.

The use of a car generator allows you to restore the battery charge, which is spent on starting the engine using a starter. At the same time, the voltage in the on-board network remains within strictly established limits, exceeding the electrochemical potential of the battery plates.

Having understood the question of why a generator is needed in a car, it is necessary to understand that in the event of a failure of the unit, the engine will work for some more time due to the battery. You can extend this period by turning off all secondary consumers: heater fan, air conditioner, audio system. When the battery runs out, the engine will shut down.

The device and design of the automobile generator

Three-phase alternating current generating sets installed on modern machines can be of 2 types: standard and compact. The general arrangement of automobile generators of 2 types is the same - they consist of the following elements:

• Pulley with shaft and bearings.
• Rotor with slip rings.
• Stator winding.
• Generator housings.
• Voltage regulator.
• rectifying device.
• Brush knot.

The designs of automotive generators differ only in layout features. With the same electrical parameters, standard units are much larger than small ones. Compactness is ensured through the use of modern materials and technologies.

Here is what the generator consists of and what functions its components perform:

• The pulley transmits rotation from the crankshaft to the rotor using a belt.
• The generator housing has two covers (front, rear) and is needed to connect the elements into a single structure. Brackets are placed on the outer surface, with the help of which the device is mounted on the engine.
• The rotor is a shaft on which excitation windings and slip rings made of electrotechnical copper are installed.
• The stator includes a magnetic circuit from a package of steel plates, in which curly grooves are cut. They contain three-phase windings from a single-core copper wire, where the current is generated.
• The voltage regulator is made as a separate unit or combined with a brush assembly. The main purpose is to control the operation of the generator by changing the current in the field winding.
• The rectifier according to the Larionov scheme consists of two parts: aluminum heat sinks, each of which has three power diodes pressed into it. The valves provide the conversion of alternating voltage to direct voltage, which is used in the on-board network to power electrical equipment.
• The voltage is transmitted to the excitation winding through a special unit and cylindrical slip rings. The brushes are made from special grades of graphite and are mounted in a holder with dielectric guides. To ensure tight contact, they are spring-loaded, and voltage is applied to them through a wire pressed into the base.

Dealing with the device of the generator of a modern car, it is necessary to single out the mechanical and electrical parts in it. The first (which includes a pulley and two rotor bearings) ensures its rotation in the housing. The second part actually generates electric current to power the on-board network. The described scheme of an automobile generator was first used in the products of the American company Neuville in 1946. Such devices were equipped with military vehicles and buses.

Main parameters of the generator

The main nominal parameters are determined based on the technical requirements for the design of a particular vehicle model:

• Voltage. In accordance with GOST 52230-2004, it is selected from the range from 7.14 to 28 V.
• Recoil current.
• The frequency of excitation and self-excitation.

The current-speed characteristic determines the dependence of the rated current of the generator on the frequency of its rotation. The voltage in the on-board network of cars and commercial vehicles, as well as buses is 12 V, especially powerful and special vehicles - 24 V. The maximum output current is determined at a rotor speed of 6,000 min-1.

Another important characteristic of this unit is efficiency. For modern models, this figure is at the level of 50-60%.

How does a car generator work?

The device begins to function only after the engine is started by a starter, which is powered directly from the battery. The key principle of the car generator is to convert mechanical energy into electrical energy. A pulley is installed on the crankshaft of the power unit, which spins the rotor mounted on maintenance-free bearings through a belt drive.

The excitation winding located on the rotating armature is powered from the battery through the brush assembly and slip rings. To protect the battery from self-discharge, the connection is made through a special rectifier consisting of three diodes. The voltage value in this circuit is regulated by an electronic or electromechanical stabilizer, integrated or made as a separate device.

The rotating armature creates electromagnetic fields that induce an alternating current in the stator windings. It goes to the rectifier, which is a block of diodes. It includes six valves: three negative and three positive. They provide the conversion of phase voltage to linear. The connection of the generator windings is carried out according to the "triangle" or "star" scheme. In the first case, the current is 1.7 times lower than in the second. The triangle is used on high-power car models.

The described principle of operation of the automobile generator ensures that the voltage in the on-board network is maintained in the range from 13.9 to 14.5 V. The exact value depends on the crankshaft speed and load level. Consumers (for example, a battery) are connected to the generating set through the “B+” terminal.

What is the purpose of a voltage regulator in a generator?

When changing the speed of the crankshaft and, accordingly, the rotor, power surges can occur in the on-board network, which adversely affect the operation of consumers. Jumps are eliminated by limiting the excitation current transmitted through the brushes from the voltage regulator to the rotor. The control is carried out by changing the connection time of the armature winding depending on the load on the on-board network.

If there is a malfunction of the regulator or damage to the brush assembly and slip rings, the battery may be undercharged or overcharged. Long-term operation of the machine with such a defect will lead to battery failure.

A generator malfunction can be identified by an indicator on the instrument panel. The battery charge light on after starting indicates insufficient voltage in the network, and blinking indicates an excess.

Conclusion

Even the most general idea of ​​​​the device and principles of operation of a car generator can help to avoid electrical equipment malfunctions. The generator starts working after starting the engine and acts as the main source of current in the car.

During the operation of the car, it is necessary to carefully monitor the tension of the drive belt, which affects the position of the generator. On a number of modern cars, the unit is firmly fixed, and a worn V-belt or V-ribbed belt must be changed immediately. Maintaining the generator in good condition will avoid large expenses for the overhaul of the car.

This material is educational and informational, and is intended mainly for those who have not dealt with cars, or have just purchased their first car. Let's consider one of the important topics, or rather, we will answer the question of what a car starter and generator are, as well as why a generator and a starter are needed in a car, what function they perform. You will learn all this in this educational material.

So let's start with the generator. The main purpose of the generator is to provide power to the electrical consumers of the car and charge the battery (battery) while the engine is running.

Over the past years, the design of the generator has changed significantly, and DC generators, as well as vibration voltage regulators, have already become a thing of the past. Now modern generators have increased specific indicators, their output power has increased, weight and dimensions have been reduced, and reliable protection elements have appeared. Generators of past years had an output current of 45-60A, and now their power has increased significantly and reaches 90-140 Amperes and even higher. All this is due to the presence of additional devices and equipment in modern cars. This includes lighting, air conditioning, heating systems and entertainment of modern cars. All this requires additional energy resources.

For trucks and buses, as well as special equipment, high-power generators are installed, which have differences compared to cars. They have differences in their design, for example, two pole systems of the rotor are installed, mounted on one shaft, they also have 2 excitation windings, and so on. For car owners, we list below the main types of generator malfunction. I would like to note that do-it-yourself repair of a starter or generator requires certain knowledge and skills. If you do not have any, then it is recommended to contact specialists in this matter.

The main types of generator malfunction:

No battery charging - the control lamp on the dashboard lights up when the engine is running (the fuse in the generator excitation circuit is blown, the drive belt is loose or damaged, there is an open or short circuit in the wiring, the voltage regulator is faulty);
The battery is discharged during the operation of the car (there is no fuse contact in the sockets, the drive belt is loose, the voltage regulator is faulty);
The battery is recharged during the operation of the car (the voltage regulator is faulty, there is no additional “+” on the voltage regulator for some generator models);
A loud noise is heard during the operation of the generator (loosening of the pulley fastening nut, the rectifier unit is faulty, contamination of slip rings and brushes, lack of lubrication in the bearings or their wear, breakage of one of the stator windings);
and so on.

Some of the leading generator manufacturers are such brands as VALEO, BOSCH, NIPPON DENCO, MAGNETI MARELLI, MOTORCRAFT, HITACHI, DELCO REMY, MITSUBISHI.