Automatic gearbox - all you need to know about automatic transmission. Automatic transmission What is an automatic box

Automatic box The gears of the car is designed to transmit the power of the engine on the wheels. It sets exactly the transmission that is best suited for the current speed of movement. Automatic transmission eliminates the driver from the need to switch the velocity manually. The computer of the car using the sensors determines which moment the speed must be switched and sends a signal to in electronic format on switching on or off transmission.

The main elements of the automatic transmission

The mechanism of the automatic transmission of the car is a system of levers and gear transmitting power to drive wheels, allowing the engine to work most effectively.

A box in an aluminum casing, called the crankcase. It contains the main components. automatic transmission:

1. The hydrotransformer performing the role of clutch, but not requiring direct control from the driver.
2. Planetary series, changing gear ratio when switching.
3. Rear, front friction, brake tape, directly carrying out shifting.
4. Control device.

How does the hydrotransformer work?

The torque converter consists of the following main elements:

• pump or pumping wheel;
• turbine wheel;
• lock plates;
• stator;
• overrogging coupling.

To understand how the automatic transmission works, it is generally necessary to represent its device. So, the pump mechanical connection is associated with the engine. The turbine wheel is connected to the PPC shaft using the slots. When the pump wheel is rotated when the engine is running, an oil flow is created, which rotates the turbine wheel of the torque converter.

In this case, the torque converter performs the role of ordinary hydromeflip, by means of a liquid only passing the torque from the engine to the shaft. With an increase in the engine speed, there is no significant increase in torque.

To convert torque, the circuit of the automatic box includes a stator. The principle of work is that it redirects the oil flow back to the impeller's impeller, causing it to quickly rotate, increasing the torque. The speed of rotation of the turbine wheel with respect to the pump is less, the greater the residual energy is transmitted by the stator by returning the oil to the pump. Accordingly, the torque increases.

Basics of the work of the turbine and pump automatic transmission

Turbine always rotates slower than the pump. The maximum ratio of the speed of rotation of the pump and the turbine is achieved with a fixed car, decreasing with increasing speed vehicle (TC). The connection of the stator with the hydrotransformer is carried out through the overtook coupling that can rotate only in one direction.

The turbines and stator blades are of particular shape, due to which the flow of oil is redirected to the opposite side of the stator blades. At the same time, the stator jars and, remaining still, it transmits the highest energy of oil to the pump inlet.

Due to this mode of operation of the hydrotransformer, the maximum torque transmission is ensured. It increases almost three times when driving a car from the spot.

When accelerating the vehicle, the turbine relative to the pump slippers less than the occurrence of the moment when the stator wheel is picked up by the flow of oil, starting to rotate in the direction of the free move of the overtook coupling. The device at the same time starts to work as an ordinary hydromefta, does not increase the torque. In this mode, the CPD of the hydrotransformer does not exceed 85%. Such a mode of operation is accompanied by the release of excess heat and an increase in fuel consumption.

Purpose of the blocking plate

This disadvantage is eliminated using a special device - blocking plates. Despite the mechanical connection with the turbine, it is structurally performed so that it can move to the right and left. This device is turned on to work when the high speed car is reached. By command, the control unit of the oil flow changes in such a way that it presses the locking plate to the torque converter body on the right.

In this case, the turbine and pump are connected to each other mechanically. To increase clutch on inner side The housing of the hydrotransformer is applied a special friction layer. Thus, the engine is associated with the output shaft of the automatic box. Naturally, such a blocking immediately turns off even with a slight braking of the car.

Above, only one of the methods of blocking the torque converter was described. However, any other way pursues the same goal - to prevent the turbine slipping towards the pump wheel. Usually the described action mode in various sources is called Lock-Up.

The operation of the hydrotransformer for dummies will be easier to understand if instead of a turbine and pump present two simple fans, one of which is running from the network, and the other rotates due to the air flow fan being created by the first fan. Only instead of air there is oil here, and the blades of the first fan (pump in the case of automatic transmission) are driven out of electricity, but due to the mechanical connection with the engine of the car engine.

Planetary rows

The torque converter can increase the torque, but only to a certain limit. The device of the automatic gearbox for a more significant increase in torque, for example, when overcoming lifting, as well as for movement, planetary rows provide for the movement. The planetary transmission also provides even switching speeds when moving without loss of motor power. Thanks to her, switching occurs without jolts, which occurs when working in the usual transmission.

The planetary series includes the following elements:

• sunny gear;
• satellites;
• epicycle;
• drove.

The planetary row is called due to the fact that friction wheels rotating simultaneously around their axes and moving along with these axes are very similar to the planets of the solar system. It depends on their mutual position, what is currently being turned on.

How to switch transmissions to automatic transmission?

Switching gear or change in the planetary gearbox of the gear ratio is carried out by blocking and unlocking the elements of the planetary row through brake tapes and friction. In the hydraulic system of the automatic transmission of the car directly shifting the gear is carried out by valve. The three-speed box has two such valves, one of which switches from the first transmission to the second, the other - from the second to the third. The four-speed box has three valves.

Other types of automatic transmission

In addition to the considered hydraulic transmission, other types of automatic boxes are widespread today:

1. Variator automatic transmission. In this type of transmission of a fixed gear ratio for transmissions does not exist. Therefore, such automatic transmission is called a stepless. The principle of operation is that, unlike other "automata", it uses the engine power more effectively. As a consequence, cars equipped with this type of transmission are more economical and comfortable.
2. Robotic checkpoint. Automatic such a box can be called conditionally, since it is essentially the usual "mechanics", where the function of the clutch pedal is assigned to the electronic unit. Cars with what boxes are also rather economical, but less comfortable, since often switching gears in automatic mode is accompanied by jerks.

Thus, in addition to the most common hydraulic automatic transmission, there are several more types of automatic boxes that differ in their design. They are distinguished by price, efficiency, comfort of car management. The general is that the driver is dispossed from the need. independent choice and switching gear.

Oddly enough, but currently automatic transmission ( automatic gearbox) Increases popularity from motorists and future car owners. (Your humble servant belongs to opponents of this type of boxes). But about it below.

So, automatic trans ...

The main purpose of the automatic transmission is the same as the mechanics - the reception, transformation, transmission and changes in the direction of torque. Available automata in the number of transmissions, according to the method of switching, software and by the type of actuators used.

The operation of the automatic transmission is better to consider on a specific example, namely on a classic three-stage gearbox with hydraulic actuators (drives) and a torque converter. It should be noted that there are preselative automatic transmission.

The automatic transmission device includes:

1. Hydrotransformer - Mechanism providing transformation, torque transmission using working fluid. Working fluid for Automatic Usually, ready transmission oil For automatic transmissions. But many motorists use liquid for hydraulic drives heavy equipment (spindle), although it is wrong. The spindle is not intended to work in the conditions of high speed of the gear movement.
2. Planetary reductor - A node consisting of "solar gears", satellites, and a planetary driving and the crown gear. Planetaryka is the main node of the automatic box.
3. Hydraulic control system - A complex of mechanisms intended to manage the planetary gearbox.

In order to more fully explain the principle of operation of the automatic transmission to begin with a torque converter.

Hydrotransformer

The torque converter serves at the same time clutch and hydromefta To transfer torque to the planetary mechanism.

Imagine two impellers with blades, located opposite each other at a minimum distance and enclosed in one case. In our case, one impeller is called a pumping wheel, which is connected hard with the flywheel, the second impeller is called turbine wheel and connected by means of a shaft with a planetary mechanism. Between blade impeller is a working fluid.

Principle of operation of the hydrotransformer

During, when the flywheel rotates, the pumping wheel rotates, its blades pick up the working fluid and direct it on the blades of the turbine wheel, under the action of centrifugal force. Accordingly, the turbine wheel blades come into motion, but the working fluid after performing the work departs from the surface of the blades and is sent back to the pumping wheel, thereby braking it. But it was not there! To change the direction of departing working fluid There is a reactor between the wheels, which also have blades and they are located at a certain angle. The following is the following - the fluid from the turbine wheel returning through the blades of the reactor hits the spacing of the pumping wheel, thereby increasing the torque, because there are two forces - engine and liquids. It should be noted that when the pumping wheel is started, the reactor is motionless. It continues until the pump turnover does not compare with the turns of the turbine wheel and standing still, the reactor will only interfere with its blades - to slow down the opposite movement of the working fluid. To exclude this process in the reactor is coupling free travelwhich allows the reactor to spin with the speed of impellers, this moment is called clutch point.

It turns out that when the nominal engine speed is reached, the engine power is transmitted to the planetary mechanism through ... Liquid. In other words hydrotransformer The automatic transmission turns into a hydromeft. So, the torque has already passed on - on the planetary mechanism?

Not! In order to transfer power from the engine, it is necessary that the drive clutch from the drive shaft has worked. But all in order ...

Planetary reductor

The planetary gearbox consists of:

1. planetary elements
2. clutch and brake couplings
3. tape brakes

Planetary element It is a node from the solar gear, around which satellites are located, which in turn are attached to the planetary drove. Around the satellites is the crown gear. Rotating, the planetary element transmits torque to the driven gear.

Clutch coupling is a set of discs and plates alternating with each other. Something Cuppet Cup is a motorcycle clutch. The clutch plates rotate simultaneously with the leading shaft, but the discs are connected to the element of the planetary row. For a three-step box of planetary series two - the first second transmission and the second third. The drive into action of the coupling is ensured by the compression of the disks and plates, this operation performs the piston. But the piston cannot move itself, it is driven by hydraulic pressure.

Ribbon brake Made in the form of a clamping plate of one of the elements of the planetary row and is driven by a hydraulic actuator.

For the concept of work of the entire box we will analyze the work of one planetary series. Imagine that the solar gear (center) slowed down (in the center), it means that the crown and satellites on the planetary drove remained. In this case, the speed of rotation will be less than the speed of the crown gear. If you allow the sun gear to rotate with satellites, and drove drove, then the crown gear will change the direction of rotation ( reverse ). If the speed of rotation of the crown gear, drove and the solar gear will be the same, the planetary row will rotate as a whole, that is, without transforming torque (direct transmission). After all the transformations, the torque is transmitted to the driven gear and then on the shank box. It should be noted that we are considering the principle of operation of an automatic transmission in which the steps are located on the same axis, such a box is designed for cars with rear wheel drive and the front engine location. For front-wheel drive cars, the size of the box must be reduced, therefore, as a few slave shafts are entered.

Thus, the braking and releasing one or several rotation elements can be achieved changes to the speed of rotation and changes in the direction. All this process controls the hydraulic control system.

Hydraulic control system

Hydraulic control system It consists of an oil pump, a centrifugal regulator, valve systems, executing devices and oil channels. The entire control process depends on the speed of rotation of the engine and the load on the wheels. When moving from a place, the oil pump creates such a pressure at which the algorithm for fixing the elements of the planetary series is ensured so that the torque at the output was minimal, this is the first transmission (as mentioned above - the solar gear is slowed down in two steps). Further, when turning turns, the pressure increases and the operation includes the second stage on reduced turns, the first stage operates in direct transmission mode. Increasing the engine speed - starts working everything in direct transmission mode.

As soon as the load on the wheels increase, the centrifugal regulator will begin to reduce the pressure from the oil pump and the entire switching process will repeat up to the opposite.

When the reduced gear on the switch lever is turned on, such a combination of the oil pump valves is selected, in which the inclusion of increased gear is not possible.

Advantages and disadvantages of automatic transmission

Chief advantage automatic transmissionOf course, serves comfort when driving - the ladies are just delighted! And, undoubtedly, the engine does not work with an automatic operation in high load mode.

Disadvantages (and they are obvious) - Low efficiency, the complete lack of "drive" when starting from the place, a large price, and most importantly - the car with a machine cannot be taken from "Tolkach"!

Summing up, let's say that the choice of box is a matter of taste and ... driving style!

Article Video How does the gearbox work automat? What are all the advantages and charms of controlling a car with an automatic box, how reliable and durable automation, which is possible and what can not be done if you have a machine gun, and whether the automatic transmission is really "stupid" as they say or can "make it »A car on the mechanics and leave it far behind? Read in this article!

Device automatic

The gearbox automat consists of several main nodes:

The location of the elements in the automatic box:

Planetary system of gears

The heart of the automatic box is the planetary mechanism.

Planetary mechanisms Have 3 degrees of freedom. This denotes that one of the 3-elements (satellites does not count) must be stopped for transmitting rotation.

If you do not stop any of the items, then everyone can perform free trafficAnd in this case there will be no rotation transmission.

You can slow down and other elements, as well as change the entry and output points, getting different gear ratios and reverse direction of rotation.

Wherein external dimensions Designs will change insignificantly. Such properties and determined the use planetary mechanisms In a box automatic.

Gearbox automatic, small video on the topic of the device:

Hydrotransformer

To transmit torque from the gearbox, the automatic machine for the engine is a torque converter. In essence, it performs almost the same functions as the grip in the mechanics.

In addition, it can increase torque due to a decrease in fluid flow rate reactor.

Principle of operation of the hydrotransformer:

The torque converter consists of three main elements.

These are two blades, one side of the box, the other from the engine side. Between them is the so-called reactor. All of these three parts are not connected mechanically, they are in a special fluid.

When rotating blades connected to the engine, the torque with a liquid is transmitted to the blades connected to the box, and the box starts working.

The geometrical characteristics of the blades of the hydrotransformer and the cross sections are selected in such a way that on the revolutions idle move The torque transmitted from the engine is very small and it can be parried even with a slight press on the brake pedal.

However, a small press on the gas pedal, and a slight increase in revolutions, causes a significant increase in the transmitted torque.

It happens because, with an increase in the engine speed, the direction of the fluid current is changed to the increase in pressure on the turbine blades

Modern automatic transformers can increase the torque transmitted from the engine from two to three times. This effect takes place only when the crankshaft rotates much faster than the input shaft of the automatic transmission.

As the speed dialing is set, this difference decreases and the moment comes when the input shaft rotates, almost at the same speed as the crankshaft, but not exactly, since the transmission of the torque from the engine on the automatic transmission is carried out through the liquid, i.e. With slippage.

This is part of the explanation why cars with automatic transmission are less economical and dynamic rather than the same with the MCPP.

To minimize these losses, the torque converters are equipped with locks. When the angular velocities of the blade wheel and the turbine are aligned, the blocking connects them into a single integer, excluding slippage.

To connect the elements of the planetary mechanism to the input shaft of the box automatize the coupling, and for stopping relative to the body of the brake. And those and others most often represent multi-disc clutches.

Hydraulic system

Working fluid in gearbox hydraulic system - aTF oil, Provides lubricant, cooling, gear shift and a transmission connection with an engine. As a rule, oil in the box is in the crankcase.

Because The volume of oil during operation is changed, it is connected to atmospheric air through the dipstick.

As Pressure source in automatic transmissionthe gear pumps with internal engagement are used. The advantage of gear pumps with internal engagement lies in high power pump, especially at low speed.

AutomaticAlso, referred to as a machine or chippet, represents a variation of the transmission of the car, which allows to reduce the load on the driver when driving as the gear selection occurs automatically, without the driver's participation. This fact has an impact on all the characteristics that cars with a box automaton possess.

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Advantages of automatic transmission

• an increase in comfort when moving cars and the release of the chauffeur from controlling third-party functions;
• smooth gear shifting and coordination of the load on the motor at the speed and power of pressing the pedal;
• motor protection from any overload;
• admission to partial or complete manual transmission control.

Types of automatic transmission

Automatic boxes modern cars You can share several types that differ in the control system and control over the operation of the automatic gearbox. The first transmission type is controlled by a hydraulic device, and the second - electronic distributor.

Types of automatic gearbox

"Inside" in both transmissions are identical, however, there are several differences in the layouts that each automatic box possesses.

All 3 types of automatic boxes briefly consider in more detail to understand their difference between themselves and the principle of operation.

Types of automatic transmission - briefly about the main thing.

Hydroavatomatom - classical automatic transmission

Hydraulic type of automatic transmission is the simplest automatic transmission. Such a box eliminates the direct connection with the engine and wheels. The torque in it is transmitted by two turbines and working fluid. Due to the improvement of the mechanism, a specialized electronic device appeared in such a box, which was also able to add such operating modes as: "Winter", "Sport", economical ride.

One of the main deficiencies, in comparison with - it is a bit more fuel consumption and time for acceleration.

Robotic automatic transmission

MTA in the people sounds like a robot DSG, structurally most similar to mechanical gearbox, but in terms of management - typical automatic transmissionwhich, as a result of evolution, not only reduce fuel consumption, but also a number of other benefits naturally with their nuances.

Variator transmission

Although it is considered an automatic box, fundamentally different and on the device and on the principle of operation. In such a gearbox, there are no steps as there is no fixed gear ratio. Drivers accustomed to listen to the motor of their car can not track her work, because the torque in the carton variator changes smoothly and the engine tonality does not change.

Components of automatic transmission

• hydrotransformerwhich replaces the clutch, and will not require the participation and management of the chauffeur.
• instead of the gear unit in automatic transmission planetary series. This part helps change the attitude to the automatic transmission when switching the transmission.
• front and rear frictionAs well as brake tape, thanks to which the gear shift is directly.
• last and most important detail - control devicewhich is a node from the gearbox pallet, pump and valve box that performs the control function. This component transmits motion data by means of signs that transmit a signal to the action of the automatic transmission.

Device and operation of an automatic transmission.

Of all the main components, we will pay the highest focus of the box of the box.

The structure of the hydrotransformer includes:

1. centrifugal pump;
2. stator;
3. centripetal turbine;
4. pumping wheel;
5. turbine wheel;

The stator is a guide device that is located between the details data. FROM crankshaft The engine is associated with a pumping wheel, and with a transmission shaft - turbine. At the reactor 2 functions. It can rotate or blocked by overtook coupling.

The main task of the hydrotransformer is the quenching of strong jokes, which are transmitted to the transmission to the engine and in the opposite direction. This unit increases the period operation of the details. With liquid oil, the torque is transmitted from the engine to the automatic transmission.

In order for the automatic transmission to work for a long time and properly, it is necessary to regularly undergo diagnostics at the maintenance station.

Pay attention to the following details:

• transmissions must switch in 1 second, the maximum time is 1.5 seconds;
• switching switching is carried out by light shocks;
• transmission should be silent.

How the automatic transmission works

In the hydromechanical automatic transmission in the classical execution, shifting gear occurs due to the interaction of planetary mechanisms and a hydromechanical drive using electronic devices.

How to use classical automatic transmission?

Features of operation of automatic transmission

• Automatic transmission it is necessary to warm wellBefore starting movement (in winter it is especially true).
• When controlling the automatic transmission to translate sleep selector lever in position P and R while drivingurgently not recommended.
• Unnecessary inclusion neutral transmission in time descent from the mountain, allegedly fuel economy- It will not all be it, but there may be problems with braking, may arise.
• You can slow down the engine not at all gearbox modes. This item must be learned in detail in the manual of a particular car, neglect of such a feature can cost expensive repair.

ACP problems and elimination methods

The most common problems of the automatic transmission are taken:

• explicitly expressed jerks when switching transmission, as well as noise when translating the selector lever to another position;
• quite often in the automatic boxes, the front and rear friction brake tape breaks;
• the output of the electrical or hydraulic unit.

It should be noted that the torque converter is a substitute for the usual clutch with a manual transmission. That is why in a car with a "machine" instead of the usual three pedals there are only pedals of brakes and gas. To move, it is enough to fix the switching lever to "Drive" and press the gas pedal.

What is the most important difference between the automatic transmission from the manual transmission?

In the previous article we considered how it was arranged mechanical box Shift shifts and found out that the transfer switching occurs when a certain gear is connected, and there are several sets. The automatic box will use only one set of gears for switching gears in its work, and allows this to make a planetary transmission.

The planetary transmission according to its size is small - as a middle melon, but it is responsible for the transfer of all possible gear ratios, and all other parts in the automatic machine only help her successfully cope with this complex task. Structurally, it includes in its composition the sun gears, followed by satellites and the corona gear. They can be fixed in a certain position, working on the input or output - thereby determined by the gear ratio.

The planetary transmission uses the blocking of some elements and unlocking others to switch gear and consists of only one central shaft, while the manual transmission of the gears and parallel shafts are engaged for this - in this advantage of the planetary transmission and automatic transmission as a whole.

Brake tape and friction

Due to the brake ribbon and climbing, blocking of certain elements of the planetary row can be performed - and this makes it possible to switch different transmissions. The braking tape blocks the elements of the planetary transmission to the ACP body (it is attached to the body), and the friction glasses allow you to block the components of the planetary row among themselves, preventing the rotation of the blocked elements counterclockwise. The braking tape has a rather high holding ability and blocks the elements of the planetary row due to the self-compliance effect.

Hydrotransformer: Durable vibration damper, which devastates severe shoes

The hydrotransformer has a turbine and pump in its design. There is a reactor between these blade machines (it looks like a wheel with shovels), which is the guide device. It can be easily blocked by the overtook clutch or simply rotate, it all depends on the conditions of movement.

The blades of the centrifugal pump are discarded on a turbine wheel, the streams of which, in fact, and transmit the torque from the engine to the automatic transmission. In order for the oil to circulate continuously, special gaps between the turbine and the pump are provided, and their blades are still given a certain geometry. It is exactly the fact that the torque is transmitted by oil streams, explains the absence of a tight touch between the checkpoint itself and the engine (in the mechanics the primary shaft is connected directly to the engine). Thanks to this scheme, it is possible to stop the car without turning off the engine.

However, we said earlier that it is not enough to pass the torque to the drive wheels, it is necessary to change it and qualitatively - a reactor copes with this task. Since it is located between the turbine and pump, its blades are located on the way to return the oil from the turbine into the pump. If the rector is fixed, the oil rate circulating between the wheels increases. And the greater the speed of the circulating oil, the greater the impact it has a turbine on the wheel. The reactor begins to rotate at the moment when the speed of the pump and the turbine turnover is beginning to be compared, thereby reducing the kinetic energy of the working fluid. This mode of operation of the reactor is customary called "hydromefta mode".

Sometimes the speed and torque is simply not needed (let's say you drive in a straight line at a constant speed), then the torque converter is blocked by friction. But as soon as the conditions of movement change (switched from constant speed in a straight line to rise to the mountain), the torque converter immediately turns on to work. With a decrease in the frequency of rotation of the turbine, the reactor will begin to be braked, as a result of which the circulating oil types the speed and automatically increase the torque indicator that is transmitted to the wheels (that is, on the shaft from the turbine). This zoom range is enough to overcome the lift without the need to switch to a lower gear.

How does the transmission turn on?

The gear shift occurs without a power break - one turned off, another turns on the other. The hydraulic pusher is driven by the oil pressure used in the hydrotransformer, after which it presses on the friction. Pressure indicator is controlled by electronics. At this moment, the clutch elements (connected hard with the shaft) are flooded. The shaft stops and the transmission turns on.

When switching the automatic transmission lever to "Drive" mode, the center torque is transmitted to the central shaft. The shaft is connected to the solar gear, while the crown gear is blocked by friction. As soon as the crown gear is unlocked, it will drop its power during rotation, and the transmission will increase. If electronic device The team came to lower the transfer, the shaft is fixed by friction, while the engine rotates the planning series solar gear. At this moment, the crown gear loses its power and the transfer drops.

For a visual demonstration of an automatic transmission device, also offer to watch Toyota video.