An alternator is an element of a car designed to produce electrical energy by converting mechanical energy (rotation of the crankshaft) into electrical energy. Generators can generate direct or alternating current.
The car generator is used as a power source for the following electrical consumers: ignition system, lighting devices, on-board computer, diagnostic systems. The generator also recharges the battery while the vehicle is moving.
Today, the most commonly used are alternating current generators, which have proven themselves well.
The device of a simple generator
The simplest generator is an ordinary rectangular frame, which is placed between magnets with different poles. To relieve stress from the rotating frame, slip rings are used.
In the automotive industry, electromagnets are used - inductors or windings of copper wire. When electric current passes through the winding, the latter is saturated with electromagnetic properties. A battery is used to excite the winding.
What is a car generator? Principle of operation, how does it work and what is it for?
Today we will find out what is called a car generator, what is the operating principle of the unit, what main components does the device consist of and how does this part of the power supply system work?
WHAT IS A CAR ALTERNATOR? PRINCIPLE OF OPERATION, HOW IS IT DESIGNED AND WHAT IS IT NEEDED FOR?
Good afternoon, today we will learn what is called a car generator
, what is
the principle of operation
of the unit, what
are
components of the device and how is
this part
the vehicle’s
power supply system arranged In addition, we will tell you about the features
, main
technical characteristics
of a car
generator
and
how the devices differ
from each other.
In conclusion, we will talk about how to properly operate
a car
generator
, why you need
a voltage regulator
in
power supply
system of a particular car, and what is called
the cooling system
of the device.
So, what is a car generator? The generator or vehicle power supply device is the main source or supplier of electricity for any modern vehicle. To understand the principle of operation of the generator, you need to know what main components this unit consists of. For reference, we note that when starting the power plant, the main consumer of current is the starter; the current at this moment can reach hundreds of amperes, which often causes a significant drop in battery charge. When the engine is started, the generator immediately becomes the main source of power supply to the vehicle equipment.
SIGNS OF GENERATOR BELT WEAR AND ITS REPLACEMENT
REPLACING THE TIMING BELT. SERVICE INTERVALS
Thus, the generator is a source of constant recharging of the battery while the engine is running. If the generator stops working, the battery will quickly discharge and die. The generator's job is to supply the required current to charge the battery and therefore ensure optimal operation of the vehicle's electrical equipment. Note that when the battery is recharged, the voltage difference between the battery and the generator becomes insignificant, which in turn leads to a decrease in the charging current in the circuit.
To understand how a generator functions, it is necessary to understand its design and the elements that ensure its optimal and uninterrupted operation. The first thing you need to start with is the drive and mounting of the generator. As a rule, the generator is driven by a part such as a crankshaft pulley. It is believed that the larger the diameter of the pulley on the crankshaft, the smaller the diameter of the pulley of the generator itself, therefore this leads to higher operating speeds of the power supply device, that is, the generator. This nuance suggests that the generator in this case is capable of delivering more current to its consumers, that is, to the electrical equipment of the car.
On most modern vehicles, the drive in the generator system is performed by a consumable element called a serpentine belt, popularly known as a rivet belt. Thanks to the extreme flexibility of this consumable element, almost any size pulley can be easily installed on the generator. This, in turn, makes it possible to obtain high gear ratios at the output, which makes it possible to use high-speed devices to supply the car with current.
An important point in the optimal operation of the generator belt is its tension, which is fixed between the tension rollers when the unit is stationary, that is, when the machine engine is not running.
DEVICE AND STRUCTURE OF A CAR GENERATOR
So, what components does one of the most important elements of a car’s electrical supply system – the generator – include? A typical generator includes a stator with a winding, which is sandwiched between two special covers. The first cover is called the front cover, it comes from the side of the drive itself and the back cover, which is located on the side of the slip rings. In most cases, generators are mounted in the area of the front part of the vehicle's power plant using special bolts located on brackets. In addition to the above-described elements, there are also mounting feet and a tensioning eyelet for the device. These parts are located on the covers. The image below clearly shows a typical circuit and the main components of a car generator.
CASE COVERS, VENTILATION NOZZLES AND GENERATOR BRUSH ASSEMBLY
As a rule, generator housing covers are made of light aluminum alloys and have special ventilation nozzles through which air penetrates and creates ventilation of the device. Typical generators are equipped with ventilation nozzles only in the end part, and compact type devices, in addition to end ventilation windows, are also equipped with holes on the cylindrical part above the frontal sides of the stator winding.
The next element of the generator that is worth considering is the brush assembly. It is located on the cover, on the slip ring side. The brush assembly is combined with a voltage regulator and a special rectifier element.
GENERATOR STATOR
The aluminum generator covers are tightened together with 3 or 4 screws so that the stator is located between the 2 covers. As for the seating surfaces, they seem to grip the stator along the outer surface. As for the stator, it consists of a core, a winding, a slot wedge, a special slot and a lead for connection to the rectifier.
The generator stator itself is made of steel sheets with a thickness of 0.8 to 1 millimeter, but sometimes it is made in the form of winding on a plate, which resembles coiled wire into a ball. When a stator package is produced by winding, the yoke of the element above the grooves often has certain protrusions. Such protrusions indicate the position of the layers relative to each other. In addition, these protrusions improve stator cooling due to the developed outer surface.
Due to the fact that every year automakers are increasingly trying to save metal in the manufacture of components for vehicles, almost 90 percent of modern stators are made in the form of wound packages, which are assembled from individual horseshoe-shaped segments. Horseshoe-shaped segments, which are manufactured in the form of separate sheets of metal, are fastened together into a single monolithic structure by welding or rivets. Most machine generators have 36 slots in which the stator winding is located. The grooves themselves are insulated with special film insulation, sometimes by spraying with an epoxy compound.
GENERATOR ROTOR
The next important element of the generator is the rotor, which has a pole system that includes pole halves, an excitation winding, slip rings and a shaft. The pole halves have 6 beak-like protrusions on each half. Pole-type halves are made by stamping and often have projections. If there are no protrusions, when pressed onto the shaft, a special bushing with an excitation winding is installed between the pole halves, which is wound on the main frame. Winding is done only after installing the sleeve inside the frame.
Rotor parts such as shafts are often made of machine-cut steel and soft alloys. As for the bearing roller, which operates at the end of the shaft from the side of the slip rings, it is made of alloy steel, plus the tip, known as the journal, is also hardened. In addition, at the end of the shaft, which is equipped with a thread, a special groove is cut for the key so that the pulley can be secured.
However, on imported cars, the key is usually missing. In this case, the end part of the shaft has a certain recess or protrusion for a key, often a hexagon. These design features help keep the shaft from turning when the pulley nut is tightened. In addition, this ensures ease of work when disassembling the generator, in the event that it is necessary to remove the pulley and fan.
GENERATOR BRUSH UNIT
Any modern generator has a brush assembly, the design of which contains special brushes, that is, sliding contacts. As a rule, 2 main types of components are used in car generators: copper-graphite
and
electrographite
. Electrographite brushes have an increased ability to drop voltage in a circuit with a ring, compared to copper-graphite brushes. This nuance negatively affects the output parameters of the generator, but they are able to provide less wear on the slip rings, since the brushes are pressed against the slip rings with spring force.
GENERATOR RECTIFIER UNITS
Also, an important role in the operation of the generator is played by rectifier units, which again come in two types
: in the form
of heat sink plates
into which power rectifier diodes are pressed using the pressing method and in the form of, on the contrary, soldered and then sealed silicon diodes. For reference, we note that in designs with increased ribbing, diodes in most cases are of the tablet type. Elements such as diodes are specially soldered to heat sinks. The diodes of the additional rectifier often have a cylindrical plastic housing. Diodes are included in the electrical circuit using busbars.
GENERATOR BEARING ASSEMBLY
They are radial ball bearings with a one-time filling of special grease, which is designed for the entire service life of the part. In addition, the bearings are equipped with seals with 1 or 2 rings, which are built into the unit. As for roller bearings, they are used on the slip ring side. The fit of ball bearings is carried out on the shaft from the side of the slip rings and is very tight, and on the drive side, on the contrary, it is sliding. The insert into the cover seat, the bearing fit on the ring side is sliding, and on the drive side it is tight, as if pressed.
GENERATOR COOLING SYSTEM
The generator cooling process occurs with the help of 1 or 2 fans, which are mounted on the generator shaft. In classic forms of the generator, air is sucked by a centrifugal fan into the cover from the side of the slip rings, and in devices that have a brush assembly, the voltage regulator with a rectifier protected by a frame is located outside the internal cavity, the air enters through the protection nozzles. Thanks to the presence of nozzles, the air is clearly directed to the hottest places, usually to the voltage regulator and rectifier.
The image above shows 3 types of generators: classic design
(
A
),
for increased temperature in the engine compartment
(B) and
standard design
(
B
), and the arrows indicate the direction of the cooling air flows.
GENERATOR VOLTAGE REGULATOR
Why do we need a regulator that controls the voltage in the generator? Everything is very simple. The fact is that the regulator ensures that the generator voltage is maintained within certain ranges to ensure optimal operation of the device and electrical equipment that is connected to the vehicle’s electrical circuit. Often, generators are equipped with semiconductor electronic voltage regulators that are built into the device. As for the principle of their operation, it is the same for everyone, however, their execution patterns and design features may vary.
For reference, we note that voltage regulators often have certain thermal compensation properties, that is, the ability to change the voltage that is supplied to the battery.
This process is carried out depending on the temperature that develops in the engine compartment in order to optimally charge the battery. For example, the lower the given temperature in the engine compartment, the greater the voltage will be supplied to the battery and vice versa. The temperature compensation indicator can reach a value of 0.01 Volt
per
1 degree
Celsius.
FEATURES AND POSSIBLE PROBLEMS IN THE OPERATION OF THE GENERATOR
The most dangerous problem in the operation of a generator is its short circuit, or rather the heat sink plates, which are connected to ground and brought to a positive charge. In the case when such a situation occurs randomly between the plates in the device, a short circuit immediately occurs throughout the entire battery circuit. The most unpleasant consequence of this problem may be a fire, and then a fire. To prevent this, many automakers today partially or completely cover some parts of the alternator rectifier with an insulating layer. In addition, manufacturers combine heat sinks with the main circuit boards into a monolithic design of the rectifier unit using insulating material that is reinforced with special connecting busbars.
Video: “What is a car generator? The principle of operation, how it works and what is it for?”
In conclusion, we note that when switching on, as well as frequent use of energy-intensive current consumers, for example, a rear or windshield heater, headlights and the presence of low engine speeds during this period of time, the total current consumption in this case becomes greater than what the generator can provide . As a rule, in this case, almost the entire load falls on the battery and it will quickly begin to discharge.
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Rules for the operation of a harmful generator (according to Oster)
Rules for the operation of a harmful generator
Here are the key rules that, if followed, will easily shut down your generator as soon as possible:
- The principle of “reversal of polarity” - swap the battery cables, and in the generator you will create an unusual bright flash, as well as a light cloud coming out of it. At the same time, you will feel an unforgettable acoustic pleasure, listening to clicks and hissing, as well as the amazing smell of burning wires, and most importantly - smoking 1-3 degrees, depending on your ambitions. This “focusing” partially suppresses the diode bridge, stator and regulator; fortunately, the car’s ignition has a chance of 1: 1000. The combination of devices, on-board computer, tape recorder and other elements of the on-board network can be turned off “from the outside.” Advantage - mastered by beginners without long theories;
- Washing principle - wash the power unit as often as possible, using plenty of water and foam, especially on the generator and starter. The main thing is that the flow of water abundantly flushes the generator from the inside; it is strictly forbidden to dry it, immediately start the engine, turn on all energy consumers and observe the effects. If not, repeat the procedure. Advantage - the burned “gene” will be pure;
- old fashioned method - the main rule is to pull the wire out of the "+" clamp to check the load on the running engine! The probability of failure of all types of relays is 50:50, the main thing is to provide plenty of sparks for the effect, as well as turn on everything that is powered by electricity;
- “Flying” through puddles - many do not even realize that they are applying this principle in the rain. The most important thing is to always be sure that your car is not comparable to the water resistance of a submarine; the deeper the puddle, the brighter the effect. It is important to choose the rate at which more water enters the engine compartment, the main thing is to throw away all the plastic covers and protective covers! The main advantage is that the trick can be repeated anywhere there is water (even streams and rivers) without leaving the car;
- “Music lover” - you need to install the most expensive radio, but preferably two, the same number of speakers, a few dozen at least, amplifiers and several subwoofers, turn on your favorite music at full volume when the engine is running, if smoke does not come out from under the hood, and the air remains clean, which means that you bought too cheap equipment;
- “Old battery” - the method requires some knowledge of physics, at least Ohm’s law. We take the oldest battery, and the older it is, the more likely it is that it will be an unopened can. The battery may show signs of hard work, it will certainly consume a huge amount of energy, but the injector will be unstable and you can forget about the traffic light. The main thing is to use the old battery more - the effect will not last long.
Signs of a generator malfunction
During the operation of the vehicle, various problems may occur in the generator - mechanical or electrical. The first group includes wear and breakdown of device components, the second group consists of various problems with the winding, brushes, failure of the voltage rectifier, relay regulator, etc.
You can promptly identify an approaching or already occurring generator breakdown by the following symptoms:
- Difficulty starting the engine . If the generator does not operate in normal mode, the efficiency of battery charging is often impaired. As a result, it receives insufficient or excess charge, as a result of which starting the engine becomes very problematic.
- Dim or flashing light . If, when driving at night, it becomes noticeable that the headlights do not shine brightly enough or the intensity of the light they create changes depending on the level of engine speed, then this indicates that the generator cannot provide the required amount of energy and voltage.
- The "Battery" indicator on the dashboard came on . This icon is always illuminated before starting the engine, after which it should go out. However, if it remains on while the engine is running, it indicates that the battery is not charging properly.
- The generator belt drive is noisy . Many motorists have heard an unpleasant whistle coming from the engine while it has not yet warmed up. It may indicate low 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.
- Ringing or unpleasant whistling from the generator housing . Such extraneous sounds indicate wear of the bearings. As a result, the rotor may begin to jam.
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Terminals for connecting generators.
The terminals of generating sets may have the following designations: positive is designated: “+”, V, 30, V+, VAT; negative output: “-“, D-, 31, B-, M, E, GRD; excitation winding output: Ш, 67, DF, F, FLD; output of the generator circuit service indicator lamp: D, D+, 61, L, WL, IND; stator phase output:
, W, R, STA; zero terminal of the stator winding: 0, Mr; positive terminal of the voltage regulator for connection to the battery: B, 15, S; regulator output connected to the ignition switch: IG; regulator output for connection to the on-board computer: FR, F.
Repair
The first thing that comes to mind with such a problem is, of course, repairing the generator brush assembly. This is a rather complex car part; two methods can be used to repair it:
- Partial.
- Full.
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In the case of partial repair, this means partial disassembly of the generator. This method should be used if you need to replace one part.
The complete method is to remove the generator from the car and completely disassemble it for parts. Try to repair the generator brush assembly in a timely manner to prevent bad consequences for the car engine.
