Automotive generator. Types and device. Work and features. Car generator: types, device, principle of operation and features of the device What does a generator look like in a car

If we compare a car with a living organism, then its engine plays the role of a heart, and as nervous system generator is acting. 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. Electrical voltage is generated due to the action 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). back paw usually has a hole in which the spacer sleeve 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.

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It would seem that what is common between a microwave, cutting-edge laser surgery and a video surveillance system? At first glance, incompatible things are united by electrical energy - in its absence, none of this can be used.

In modern society, all the necessary conditions have been created for connecting to a constant source of electricity. But still, from time to time there are situations when you have to take care of uninterrupted power supply on your own. In cases of failures, malfunctions or outages on power lines, an autonomous power generator will become a real find.

It is clear that you can do without a hair dryer and an electric coffee maker for some time, but what about the heating system of a private house or refrigeration units that cool some vaccines, for which even a short-term power outage is dangerous, or how to provide electricity to a construction site - having your own electric generator will be ideal solution to all of the above problems. Fortunately, modern industry can satisfy any need.

Among the wealth of types of generators, the most popular today are gasoline and diesel. Such popularity is due to small size, economy, mobility and relatively low cost.

The choice of generator type determines the purpose of its operation. In cases where the generator is considered as an emergency power source, it is better to opt for the gasoline version. At a lower cost, it is also much lighter, which is not unimportant when transporting and moving. It is also good for a picnic or fishing trip.

Diesel generators are the choice of those who need an alternative main power source. The peculiarity of diesel engines allows you to create powerful power plants on their basis that can provide power to small businesses, hospitals and other social facilities. Household diesel generators will fully provide electricity to a house or cottage. Of course, they are more expensive and bulky.

Generators are used in different ways: in conditions when electricity is periodically turned off or when there is not enough voltage in the network (overload of current transmission lines, regular and unforeseen shutdowns), and in places where it is constantly absent (garages, construction sites, greenhouses, trading platforms). In addition, there are special-purpose power generators, for example, three-phase or 12-volt ones specifically for charging car batteries.

Whatever option you choose, with proper care and proper operation, it will become an indispensable assistant and will be able to bring warmth and comfort to the house, and enterprises and offices - the opportunity to fully work.

The generator is the main source of electricity for the machine. We will tell you how it works, what its device consists of.

How does he work?

The generator is a source of constant recharging of the battery while the engine is running. If it does not work, the battery will quickly run out. It provides the required current to charge the battery and operate electrical appliances. After recharging the battery, the generator reduces the charging current and operates normally.

When powerful consumers are turned on (for example, a rear window defroster, headlights) and low engine speeds, the total current consumed may be greater than the generator is capable of delivering. In this case, the load will fall on the battery and it will begin to discharge.

Drive and mount

On modern machines, the drive is carried out by a V-ribbed belt. Due to its greater flexibility, it allows the generator to be fitted with a small diameter pulley and thus obtain high gear ratios. V-ribbed belt tension carried out by tension rollers with a stationary generator.

The device and what does it consist of?

The covers, cast from aluminum alloys, have ventilation windows through which air is blown by a fan. Generators of traditional design are equipped with ventilation windows only in the end part, and "compact" design - on the cylindrical part above the front sides of the stator winding.

On the cover from the side of the slip rings, a brush assembly is attached, which is combined with a voltage regulator, and a rectifier assembly. The covers are usually pulled together by three or four screws, and the stator is sandwiched between the covers, the seating surfaces of which cover the stator along the outer surface.

Generator stator: 1 - core, 2 - winding, 3 - grooved wedge, 4 - groove, 5 - output for connection with a rectifier

The stator is made of steel sheets with a thickness of 0.8 ... 1 mm, but more often it is wound "on edge". When the stator package is made by winding, the stator yoke usually has protrusions above the grooves, along which the position of the layers relative to each other is fixed during winding. These projections improve the cooling of the stator due to the more developed outer surface.

The need to save metal led to the creation of the design of the stator package, recruited from separate horseshoe-shaped segments. The fastening between the individual sheets of the stator package into a monolithic structure is carried out by welding or rivets. Almost all mass-produced car generators have 36 slots in which the stator winding is located. The grooves are insulated with film insulation or sprayed with epoxy compound.

Automotive Alternator Rotor: a - assembled; b - disassembled pole system; 1.3-pole halves; 2 - excitation winding; 4 - contact rings; 5 - shaft

A feature of automotive generators is the type of rotor pole system. It contains two pole halves with protrusions - beak-shaped poles, six on each half. The pole halves are stamped and may have projections. In the absence of protrusions, when pressing onto the shaft, a bushing with an excitation winding wound on the frame is installed between the pole halves, while winding is carried out after the bushing is installed inside the frame.

Rotor shafts are made of mild free-cutting steel. But when using a roller bearing, the rollers of which run directly along the end of the shaft from the side of the slip rings, the shaft is made of alloy steel, and the shaft pin is hardened. At the threaded end of the shaft, a groove is cut for the key for attaching the pulley.

In many modern designs, the key is missing. In this case, the end part of the shaft has a recess or a turnkey protrusion in the form of a hexagon. This allows you to keep the shaft from turning when tightening the pulley mounting nut, or when disassembling the generator, when you need to remove the pulley and fan.

brush knot- this is a structure in which brushes are placed i.e. sliding contacts. Two types of brushes are used in automotive alternators - copper graphite and electrographite. The latter have an increased voltage drop in contact with the ring compared to copper-graphite ones. They provide significantly less wear on the slip rings. The brushes are pressed against the rings by the force of the springs.

Rectifier nodes two types are used. These are either heat sink plates into which power rectifier diodes are pressed, or structures with highly developed fins and diodes are soldered to heat sinks. The diodes of the additional rectifier usually have a plastic case of a cylindrical shape or in the form of a pea, or they are made in the form of a separate sealed unit, the inclusion in the circuit of which is carried out by busbars.

The most dangerous is the closure of the heat sink plates connected to the "mass" and the "+" terminal of the generator with metal objects accidentally caught between them or conductive bridges formed by pollution, tk. this causes a short circuit in the battery circuit and a fire is possible. To avoid this, the plates and other parts of the generator rectifier are partially or completely covered with an insulating layer. In a monolithic design of the rectifier unit, heat sinks are mainly combined with mounting plates made of insulating material, reinforced with connecting bars.

The generator is cooled by one or two fans mounted on its shaft. At the same time, in the traditional design of generators, air is sucked in by a centrifugal fan into the cover from the side of the slip rings. For generators with a brush assembly, a voltage regulator and a rectifier outside the internal cavity and protected by a casing, air is sucked in through the slots in this casing, directing air to the most heated places - to the rectifier and voltage regulator.


Cooling system: a - devices of conventional design; b - for elevated temperature in the engine compartment; c - compact design devices. The arrows show the direction of air flow
On cars with a dense layout of the engine compartment, generators with a special casing are used, through which cold outside air enters it. For "compact" generators, cooling air is taken from both the rear and front covers.

What is a voltage regulator for?

Voltage regulators have the property of thermal compensation - changing the voltage supplied to the battery, depending on the air temperature in the engine compartment for optimal battery charging. The lower the air temperature, the more voltage must be supplied to the battery and vice versa. The value of thermal compensation reaches up to 0.01 V per 1°C. Some models of remote regulators have manual voltage level switches (winter/summer).

Since the operation of any internal combustion engine requires electrical energy, and the possibilities of the battery are not unlimited, and the battery is only enough to start, the car generator is engaged in the generation of electricity. In addition to the fact that this device provides all consumers with electricity, part of the generated current is spent on charging the battery and self-exciting the rotor. Let's see how the generator works and how it works.

Purpose

In addition to supplying electricity to the on-board network, the car generator is also necessary to restore the supply of electricity that the battery lost during engine start. Initially, the winding is excited by direct current to the battery. The generator then generates electricity on its own. The rotation of the generator is transmitted from the crankshaft through a pulley and a belt drive.

Without a properly functioning alternator, the car will be able to start. But he won't get far. Starting the car next time may not work - the battery is not recharged, and it simply does not have enough opportunities for the next engine start.

Operating principle

The operation of a car generator is completely based on the physical laws of electromagnetic induction. With the help of this phenomenon, mechanical energy can be transformed into electrical energy. A similar effect will appear if a coil of copper wires is placed in the area of ​​influence of an alternating magnetic field.

This will promote the formation of an electrical force in the coil and wires, which will make the electrons move. Then, through this movement, a current will appear at the terminals of the coil. Voltage will appear on the wire contacts. But its level depends on how quickly the magnetic field changes. The resulting voltage as a result of the operation of the generator is variable, and it will be supplied to external consumers.

Specifications

The current-speed characteristics of automobile generators are responsible for the process of providing all consumers with electrical energy in the generator. This is the dependence of the maximum current on the frequency of rotation of the armature. In this case, you need to know how much current in amperes the installation is capable of delivering. The possibilities are in the range of 55-120 amperes. If, during operation, the device does not produce a sufficient amount of current, then it is faulty.

There are also external, adjustment, load characteristics and idle speed indicators.

Device

The device of a car generator is actually simple. To create a magnetic field, a special element is used in it - a stator. This element is a winding. In the magnetic field created by the stator, the rotor or generator armature rotates. The rotor is a specially designed shaft. It is also equipped with windings. The latter are connected to the rings - they are necessary to supply voltage to the rotor.

Fastening

Even a beginner can easily find a car generator in the engine compartment. It is attached to the engine with bolted connections. Mounting paws and a special tension eye are provided on the body, which serves to tighten the drive belt.

Frame

Almost all blocks and nodes of such a device are located in the case. Housings for generators are made of alloys, one of the properties of which is low weight. Often the main component of such alloys is aluminum. It is excellent for these tasks - aluminum copes well and effectively with heat transfer to the atmosphere. The body consists of two parts. This is a cover and end cap.

A brush assembly and a diode bridge serving as a rectifier are fixed on the front part. Each of the covers forms an integral structure with each other by means of a bolted connection with special bolts. Both covers from the inside securely hold the outer part of the rotor shaft.

The building also has two more important details are bearings. Most generators use two bearings: one is rear, the other is front. Both bearings provide the rotor shaft with the ability to rotate.

How is the rotor arranged?

The rotor assembly is a construction of electromagnets and an excitation coil. These two elements are mounted on the same shaft. The latter is made mainly of alloy steels with a low content of additives in the form of lead.

On the rotor shaft there are also rings and current-collecting brushes with spring-loaded contacts. Slip rings are needed to supply current to the rotor.

stator

We continue to study the device of a car generator. The stator is a node, which is a core with a large number of grooves. In most models, there are 36 such grooves. Wire turns of three windings are embedded in them. The windings are connected to each other according to the "star" or "triangle" scheme. The core or magnetic circuit is made in the form of a circle. It is set with metal plates. The plates are connected to each other by means of rivets or welding. The core is a monolithic assembly.

To increase the level of tension, special transformer iron is used on the stator windings in the production of plates. It has enhanced magnetic characteristics, unlike ordinary.

Voltage regulator

Automotive alternator voltage regulators are used to compensate for instability during rotation of the rotor, which is connected to the engine crankshaft via a drive belt. The crankshaft operates in a wide range of revolutions. The regulator is connected to graphite brushes and is designed to stabilize the constant output voltage, which enters the electrical network of the car.

Without a regulator, it will be impossible to start the generator. In addition, even if the start succeeds, it will not be possible to control the current supply. Regulators can hold the current in certain intervals.

The principle of operation of the relay-regulator

If you connect a winding without a relay-regulator to a source of electricity, then the level of direct current will be high. With the help of a relay in the circuit, this parameter is aligned so that the electrical equipment in the car does not fail. In fact, the relay-regulator of a car generator is something like a switch. If the voltage rises to 13-14 volts, the device automatically turns off the winding and turns it on when the current is lower. As a result, regular wiring connections/disconnections allow the generator to produce higher voltage.

How much such a device should produce is not important. Once the energy has been generated, it must be rectified. For these purposes, the generator is equipped with a diode bridge. Since the voltages are large, the regulator is switched on, the element instantly responds to changes in current strength. This information is then sent to the comparator. It is needed to analyze the testimony and compare with those that have just arrived. If the voltage of the car alternator is low, then the regulator will increase the DC current in the circuit, thereby increasing it to the required level.

Types of regulators

Various generators use different types relay regulators. These are two-level devices, electronic devices, three-level, multi-level.

The first two-level relays are considered obsolete today. But motorists, despite this, continue to actively use them in car generator connection diagrams. At the heart of such a two-level regulator is an electric magnet connected to a sensor on the winding. Springs act as a master element - there are several of them. A movable lever acts as a comparing component - it also switches the wiring. The main drawback of this type of regulators is a small resource.

Electronic models of regulators with a limiting current of a car generator up to 40 A are semiconductor. They have a great resource. As for their malfunctions, compared to their two-level counterparts, breakdowns are less common here.

Three-level solutions practically do not differ from the above-considered regulators. The only difference here is that these devices also have additional resistance.

Multilevel solutions are another type of relay-regulators. They have three or even five resistances. In addition, models with a tracking mode of operation are on sale.

Diode bridge or alternator rectifier

Since a direct current is needed for the normal operation of the electrical equipment of cars, the output of the car generator feeds the power grid through a special assembly assembled on rectifier diodes.

The design is a three-phase rectifier. It has six diodes - three are connected to ground, and three more - to the positive contact of the unit. They are designed to convert AC voltage to DC.

Generator brush assembly

This item is a plastic construction. It is necessary to transmit voltage to the slip rings on the rotor. There are several details inside. However, the main ones among them are spring-loaded brushes. They can be electrographite or more resistant to wear - copper graphite.

Structurally, in modern generators, the brush assembly is a single unit with a relay-regulator.

Cooling

During operation, the generator may heat up significantly. Excess heat is removed by a fan mounted on the rotor shaft. Generators with brushes, a regulator and a rectifier are placed outside the housing with a protective cover. Devices take cold air through slots.

Operating modes

To understand how the oscillator works, you need to have a little idea in what modes it is operated. There are only two such modes First stage at the time of starting the engine and operating mode.

At the time of starting the power unit, the main device that consumes electricity is the starter. The generator has not yet been started and is not producing electricity. Due to the fact that the starter consumes current, the battery has to spend energy intensively.

After the motor enters its main operating mode, the generator will begin to provide all consumers with electricity. It will generate the current that is needed for the operation of the main consumers. Along with this, the power of the car generator is also enough to recharge the battery. As more powerful consumers are included in the work, the generator may not be enough. Then the energy comes from the battery as well. In this case, the battery charge is consumed very quickly.

Generator repair

Generator breakdowns can be very different. In one case, it is enough to replace the diode bridge for repair, in the other, it is enough to replace more significant parts.

So, among the main malfunctions is the failure of the circuit. It can be breaks, short circuits, any other violations. In this case, the repair of a car generator is to check what current and what voltage the generator produces. Then a solution is chosen. Also, one of the breakdowns is the wear of graphite brushes or diodes in the rectifier bridge. All these malfunctions are easily fixed by hand.

Noise during generator operation indicates defects in bearing assemblies, as well as insufficient lubrication. Wear of separators, turning of rings is also possible. With howling sounds, you can notice such breakdowns as the interturn circuit of the stator windings. In such cases, it is better to entrust the repair of the unit to professionals.

Conclusion

So, we found out what a generator is. As you can see, this is quite a significant and necessary element in any car.

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’ll immediately make a reservation that we will be talking about a car generator alternating current, 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 that the voltage of the on-board network of the machine is always within the specified limits, regardless of the load, temperature environment and rotor performance.

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 starts to rotate, as you remember, thanks to the pulley, the generator rotor also starts 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 the speed of its rotation, then in this system the voltage regulator is turned on. 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: