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:
- Hydrotransformer - Mechanism providing transformation, torque transmission using working fluid. Working fluid for Automatic Usually, ready-made transmission oil for automatic gearboxes. 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.
- 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.
- 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 travel which 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:
- planetary elements
- clutch and brake couplings
- 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 drilled, 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!
Vehicles with an automatic transmission switch every year becomes more and more. And, if we have - in Russia and the CIS - "Mechanics" still continues to prevail in front of the "automatic", then in the west of cars with automatic transmission, now the overwhelming majority. It is not surprising if you take into account the indisputable advantages of automatic boxes: simplifying the car management, stable smooth transitions from one transmission to another, engine protection from overloads, etc. Adverse mode of operation, improving the driver's comfort while driving. As for the shortcomings of this transmission option, modern automatic transmission as it improves gradually get rid of them, make them insignificant. In this publication, about the device of the "automaton" box and all its advantages / minuses in work.
An automatic transmission is called such a type of transmission, which provides automatic, without direct exposure to the driver, select a gear ratio, most of all relevant relevant conditions vehicle movement. The variator does not apply to the automatic transmission and stands out in a separate (infinitely) transmission class. Because the variator produces changes gear ratios Smoothly, in general without any fixed steps-gears.
The idea to automate gear shifting, having robbing the driver from the need to often squeeze the clutch pedal and "work" the switching lever, not Nova. She began to introduce and hurry at the dawn of the automotive era: at the beginning of the twentieth century. Moreover, it is impossible to call any definite man or the company the only creator of the automatic transmission: to the appearance of a classic, which now obtained the universal spread of the hydromechanical automatic transmission has led three initially independent developments lines, which ultimately united in a single design.
One of the main mechanisms of the box-machine is a planetary series. The first serial car equipped with a planetary transmission was released back in 1908, and it was Ford T. Although, in general, the transmission box was not yet fully automatic (from the Ford T driver it was necessary to press two foot pedals, the first of which translated from the lowest to the highest transmission, and the second turned on the reverse), it already allowed much to simplify control, Compared with conventional gearbox for those years, without synchronizers.
Second important moment In the formation of future automatic transmission technology, this is the transfer of a clutch management from the driver to servo drive, embodied in the 1930s of the twentieth century by General Motors. These gear shift boxes were semi-automatic. The first fully automatic gearbox was introduced into production in the 30s of the twentieth century, the Planetary Electromechanical Box "Kotal". She was installed on French cars forgotten brands "Delazh" and "Delea" (existed until 1953 and 1954, respectively).
The car "Delling D8" is a premium class of a pre-war era.
Other auto industrymen in Europe also developed similar system of friction and brake ribbons. Soon, similar automatic transmission was implemented in cars of several more German and British brands, the well-known healthy helicate of which is "Maybach".
Specialists are other famous firm - American Chrysler advanced further than other automakers, introducing hydraulic elements into the design of the CAT, which replaced servo drives and electromechanical controls. Engineers "Chrysler" have developed the first hydrotransformer and hydromefluoride in history, which are now in the design of each automatic gearbox. And the first in the history of the hydromechanical box - automatic, similar to design on modern, on serial cars was introduced by General Motors Corporation.
Automatic transmissions of those years were very expensive and technically complex mechanisms. In addition, not always distinguished reliable and durable work. They could win only in the era of non-chronic mechanical boxes Transmissions, controlled by a car with which was enough difficulty, requiring the driver of a well-worked skill. When widely spread mechanical PPC With synchronizers, then on the convenience and comfort of the automatic transmission of the level were not very better than them. While the MCPP with synchronizers possessed much less complexity and high cost.
In the late 1980 / 1990s, all major automakers had a computerization of the engine control systems. Similar systems began to apply both speed switching. If the previous solutions were used only hydraulics and mechanical valves, now the fluid flows control the solenoids controlled by a computer. It made the switching smooth and more comfortable, improved efficiency and increased the efficiency of the transmission.
In addition, some cars were introduced "sports" and other additional modes of operation, the ability to manually control the gearbox ("Tiptronic", etc. Systems). The first five- and more stepped automatic transmission appeared. Perfection supplies allowed many box machines to cancel the oil replacement procedure during the operation of the car, since the resource of the oil is filled into its crankcase in the oil plant has become comparable to the resource of the gearbox itself.
Construction of an automatic transmission
Modern box-machine, or "Hydromechanical transmission", consists of:
- torque torque converter (hydrodynamic transformer, GDT);
- planetary mechanism automatic switching gears; brake tape, rear and front friction - devices that directly switch transmissions;
- control devices (node \u200b\u200bconsisting of a pump, valve box and oil separator).
The torque converter is needed to transmit torque from power aggregate To the elements of the automatic transmission. It is located between the box and the engine, and thus performs the clutch function. The torque converter is filled with the working fluid, which catches and transmits the engine energy into the oil pump itself in the box.
A hydrotransformer consists of large wheels with blades immersed in special oil. Torque transmission is not carried out mechanical device, and with the help of oil flows and their pressure. Inside the torque converter, a pair of paddle machines are located - a centripetry turbine and a centrifugal pump, and between them - the reactor, which is responsible for smooth and stable changes in torque on the drives to the vehicle wheels. So, the hydrotransformer does not contact the driver or with the clutch (it "itself is" the grip).
The pumping wheel is connected to the engine crankshaft, and turbine, with transmission. When the pumping wheel is rotated, the oil threads are spinning the turbine wheel. So that the torque can be changed in wide ranges, a reactor wheel is provided between the pumping and turbine wheels. Which, depending on the car mode, can be either fixed or rotated. When the reactor is fixed, it increases the flow rate of the working fluid circulating between the wheels. The higher the speed of the oil, the greater the impact it has a turbine wheel. Thus, the moment on the turbine wheel increases, i.e. The device "transforms".
But the torque converter cannot convert the rotation speed and the transmitted torque in all the required limits. Yes, and ensure movement reverse It is also not in force. To expand these capabilities to it and attaches a set of separate planetary gears with a different gear ratio. As if several single-stage gearbox collected in one case.
Planetary transmission is mechanical systemconsisting of several satellite gear, which rotate around the central gear. Satellites are fixed together with a circle-drove. The outer ring gear has an internal gearing with planetary gears. Satellites, fixed on the driver, rotate around the central gear, like planets around the sun (from here and the name of the mechanism - "Planetary Transfer"), the outer gear rotates around satellites. Various gear ratios are achieved by fixing different parts relative to each other.
Brake tape, rear and front friction - directly produce shift gears from one to another. The brake is a mechanism that locks the elements of the planetary row to the fixed body of the automaton. The cluster blocks the moving elements of the planetary row among themselves.
Automatic CAT control systems are 2 types: hydraulic and electronic. Hydraulic systems are used on outdated or budget models, and are gradually derived from use. And all modern boxes are "automata" are controlled by electronics.
Life support device for any control system can be called an oil pump. Its drive is carried out directly from crankshaft Engine. Oil pump creates and supports hydraulic system Permanent pressure, regardless of the rotation frequency of the crankshaft and loads on the engine. In the case of a pressure deviation from the nominal operation of the automatic transmission, it is violated by the fact that executive mechanisms Transmission are controlled by pressure.
The gearbox is determined by the velocity of the vehicle and the load on the engine. To do this, the hydraulic control system provides a pair of sensors: a high-speed controller and a throttle valve, or a modulator. The high-speed pressure regulator or hydraulic speed sensor is installed on the output shaft of the automatic box.
The faster the vehicle is going, the more the valve opens, and the greater the pressure passing through this valve transmission fluid. Intended to determine the load on the engine valve-throttle is connected by the cable or with throttle valve (if we are talking about gasoline engine) or with a lever fuel pump high pressure (in a diesel engine).
In some cars for supplying pressure on the throttle valve, it is not used, but a vacuum modulator, which is driven by discharge in the intake manifold (with an increase in the load on the engine, the discharge drops). Thus, these valves create such pressure, which will be proportional to the velocity of the vehicle and the engine loading. The ratio of these pressures and allows you to determine the moments of gear shift and blocking the torque converter.
In the "Fishing Moment" of switching the transmission takes part and the valve of the range selection that is connected to the ACP selector lever and, depending on its position, it permits either prohibits the inclusion of certain gears. The resulting pressure that the throttle valve and the high-speed controller creates the corresponding switching valve. Moreover, if the machine accelerates quickly, the control system will turn on the increased transmission later than when overclocking is calmly uniform.
How it's done? The switching valve is under the pressure of the oil from the high-speed pressure regulator on the one hand, and from the throttle valve - on the other. If the machine accelerates slowly, the pressure from the hydraulic velocity valve goes on the increasing, which leads to the opening of the switching valve. Since the accelerator pedal is not completely pressed, the throttle valve does not create a large pressure on the switch valve. If the car accelerates quickly, the throttle valve creates greater pressure on the switch valve, and prevents it from opening. To overcome this opposition, the pressure from the high-speed pressure regulator should exceed the pressure from the throttle valve. But this will happen when a high speed car is achieved than it happens during slow acceleration.
Each switch valve corresponds to a specific level of pressure: the faster the car moves, the more higher transmission turns on. The valve block is a system of channels with valves and plungers located in them. Switching valves are fed by hydraulic pressure on actuators: friction clutches and brake tapes, by means of which the various elements of the planetary row are blocked and, therefore, turning on (off) of various gears.
Electronic control system Just like the hydraulic, uses 2 basic parameters for operation. This is the speed of the vehicle and the load on its engine. But to determine these parameters, not mechanical, but electronic sensors are used. The main ones are working sensors: rotational speed at the input of the gearbox; Rotation frequency at the output of the gearbox; Temperatures of the working fluid; position of the lever of the selector; The positions of the accelerator pedal. In addition, the control unit of the "automat" receives additional information from the engine control unit, and from others electronic systems Car (in particular, from ABS - anti-lock system).
This allows you to more precisely than in the usual automatic transmission, to determine the moments of the need for switching or in the torque of the torque converter. The electronic gear shift program by the character of a speed change at a given load on the engine can easily and instantly calculate the power of resistance to the movement of the car and, if necessary, adjust: enter the appropriate corrections in the switch algorithm. For example, further include increased transmissions on a fully loaded vehicle.
Otherwise automatic transmission with electronically control Just as the usual, "not burdened by electronics" hydromechanical boxes, use hydraulics to turn on the couplings and brake ribbons. However, they have each hydraulic circuit is controlled by an electromagnetic, not a hydraulic valve.
Before starting the movement, the pump wheel rotates, the reactor and turbine remain in a stationary state. The reactor wheel is fixed on the shaft by means of an overtaking coupling, in connection with which it can only rotate in one direction. When the driver turns on the gear, presses the gas pedal - the engine turns grow, the pump wheel is gaining momentum and oil fluxes the turbine wheel.
The oil dropped back into the turbine wheel falls on fixed reactor blades that additionally "twisted" the flow of this fluid, increasing its kinetic energy, and direct on the blades of the pumping wheel. Thus, with the help of the reactor, the torque increases, which is required by the vehicle, gaining acceleration. When the car accelerates, and started moving at a constant speed, then the pumping and turbine wheels rotate approximately with the same turnover. Moreover, the flow of oil from the turbine wheel falls on the reactor blades already on the other hand, thanks to which the reactor begins to rotate. The increase in torque does not occur, and the torque converter enters the uniform hydromeflua mode. If the resistance of the car's movement began to increase (for example, the car began to ride on the rise, uphill), then the speed of rotation of the leading wheels, and, accordingly, the turbine wheel, falls. In this case, oil streams again slow down the reactor - and the torque increases. Thus, automatic torque control is performed, depending on changes in the mode of motion of the vehicle.
The absence of a rigid connection in the hydrotransformer has both advantages and disadvantages. Pluses are that the torque varies smoothly and steplessly, the tweaks are damped and jerks, transmissions transmitted from the engine. The minuses consist primarily in the low efficiency, since a portion of the useful energy is simply lost with the "shocking" of the oil fluid and is consumed to the automatic transmission pump, which ultimately leads to an increase in fuel consumption.
But to smooth this shortage in the hydrotransformators of modern automatic transfers, the lock mode is used. With the steady mode of movement on higher transmissions, the mechanical locking of the hollows of the torque converter automatically turns on, that is, it begins to perform the function of the usual classic clutch mechanism. It provides a hard direct connection of the engine with leading wheels, as in mechanical transmission. On some automatic transmission, the inclusion of the blocking mode is also provided on the lower gears too. The motion with blocking is the most economical mode of the "automatic" box. And when loading the load on the drive wheels, the lock is automatically turned off.
During the operation of the hydrotransformer, there is a significant heating of the working fluid, which is why the automatic box design provides a cooling system with a radiator, which is either embedded in the engine radiator, or is installed separately.
Any modern box "Automatic" has the following mandatory provisions on the cockpit-selector:
- P - Parking, or Parking Lock: Locking leading wheels (does not interact with parking brake). Similarly, as on the "mechanics", the car leaves "at speed" when setting for parking;
- R is a reverse, reverse transmission (it has always been forbidden to be activated at the time of the vehicle movement, and then in the design there were appropriate blocking);
- N - neutral mode, mode neutral transmission (activated with a short parking lot or towed);
- D - Drive, movement in front of the front (in this mode, the entire transmission row of the box will be involved, sometimes two higher transmissions are cut off).
And may also have some additional, auxiliary or extended modes. In particular:
- L - "Redeyaka", activation of the reduced transmission mode (small stroke) in order to move in complex roads or in off-road conditions;
- O / D - Overdrive. Saving mode and measured movement (with any possibility, the "automatic" switches to the top);
- D3 (O / D OFF) - the deactivation of the highest level for the active ride. Involved in braking by a power unit;
- S - transfers are spinning to maximum revolutions. It may be possible manual control Box.
- A special button may be present at the automatic transmission to a higher transmission during overtaking.
Advantages and disadvantages boxes "automaton"
As already noted, weighing the advantages of automatic gearboxes, compared to mechanical, are: simplicity and comfort of controlling the driver for the driver: the clutch is not necessary to squeeze, "work" the gear shift lever is also. This is especially true on trips around the city, which make up, ultimately, the lion's share of the car run.
Transmission on the "Automat" are obtained more smooth and uniform, which contributes to the protection of the engine and the leading vendors of the car from overloads. Consumables (for example, a clutch or cable disc) are absent, therefore, it is more complicated in this sense. In general, the resource of many modern automatic transmission exceeds the resource of mechanical gearboxes.
The disadvantages of automatic transmissions are more expensive and complicated than that of the MCPP, the design; The complexity of repair and its high cost, lower efficiency, worse dynamics and elevated, compared with the MCPP, fuel consumption. Although, the improved electronics of the "automata" of the XXI century copes with right choices torque is no longer worse than an experienced driver. Modern automatic transmission gearboxes are often equipped with additional modes that allow you to adapt to a certain style of driving - a calm up to "frisky".
A serious disadvantage of automatic gearboxes are the impossibility of the most accurate and safe gear shift in extreme conditions - for example, on complex overtaking; On the road from a snowdrift or serious mud to quickly switching the rear and first gear ("in a split"), if you need to start the engine "from the Tolkach". It must be recognized that the automatic transmission is ideal, mainly for ordinary trips without freelance situations. First of all, in city roads. The "automata" and for "sports driving" are not very adapted (the dynamics of overclocking is slightly behind the "mechanics" in a bundle with a "advanced" driver ", and for a rally on a bomadroziness (it does not always be perfectly adapted to change the conditions of movement).
As for the fuel consumption, the automatic box can in any case be more than that of mechanical. However, if earlier this indicator was 10-15%, then modern cars It fell to at least significant marks.
In general, the use of electronics has significantly expanded the possibilities of automatic gearboxes. They received various additional modes of operation: such as - economical, sports, winter.
A sharp increase in the prevalence of boxes "automata" was caused by the appearance of the "AutoStick" mode, which allows the driver, if desired, to choose the necessary transmission independently. Each manufacturer has given such a type of automatic transmission of its name: "Audi" - "Tiptronic", "BMW" - "Steptronic", and the like.
Due to advanced electronics in modern automatic transmission, the possibility of "self-improvement" has become available and the possibility of "self-improvement". That is, changes in the switching algorithm, depending on the specific style of driving the "host". Electronics provided advanced capabilities as well for self-diagnosis of automatic transmission. And we are not only about memorizing fault codes. The management program, controlling the wear of friction discs, oil temperature, promptly makes the necessary adjustments to the operation of the automatic transmission.
Automatic box Speed \u200b\u200bswitching is a type of gearbox, which provides an automated selection of speed, according to driving conditions. We offer you to find out in detail what the automatic box is from which components it consists and what principle of operation of the automatic transmission.
The development of the automotive industry does not stand still, and many new items make driving for a motorist not only more convenient, but also more pleasant. If we talk about automobile comfort, then the automatic transmission is immediately comes to the mind - an automatic transmission, which has eased the life of motorists more than other innovations. This is especially true of those drivers who do not want to drive on the "mechanics".
"Automatic" tried to adapt in the domestic market for a very long time. And, nevertheless, before that time, when these aggregates are used for most of our roads, it is still very far away. But in the last few decades with traditional automatic transmission manufacturers vehicle Other options for automatic ("robotic") transmissions are offered.
Against the background of mass technology, this type of gearbox has something in common with the usual "automaton" only in part. Most popular and reliable sample robotic gearboxes are boxes DSG. From the producer of Volkswagen.
[Hide]
Structure of ACP
Automatic transmission differs from mechanical automated switching of speeds and other principle of action of the entire mechanical part. Here we are talking about the use of planetary devices and a hydromechanical mechanism instead of the usual mechanical in the standard checkpoint.
As for the usual "automata", in their structure they consist of:
- hydrotransformer;
- devices - planetary gearboxes;
- moving and overtaking couplings;
- various pulleys and drums connecting between themselves;
- a brake belt intended for braking one of the drums relative to the body of the automatic gearbox, during the speed of speed.
Such a structure is almost all automatic transmissions. The exception is only a Honda car box - in such gearbox, the planetary device was decided to replace the pulleys with gears.
The hydrotransformer in "automata" is set in the same way as the grip in the "mechanics". The housing itself of this unit with the leading turbine is installed on the motor flywheel as well as the clutch basket. Main destination this device It is to transfer torque with slipping when touching from the spot. If the vehicle moves to increased turns Motor - on the 3rd or 4th speed - the device performs lock, thanks to the moving coupling, which makes the slipping is actually impossible. Thus, in automatic gearboxes, excess energy costs and gasoline consumption for friction of transmission fluid in turbines are disappeared.
The principle of functioning of the "Automatic" box
Now consider how the automatic transmission works. If you try to disassemble the "automatic" and look inside, you will see a wide variety of various mechanisms and devices in a relatively small space.
The principle of operation of a planetary series with gearboxes is to create gear ratios. In essence, all other components of the transmission system are designed to help the planetary row to perform this function.
The hydrotransformer itself includes several components:
- entrance turbine;
- output turbines;
- stator.
Often the stator is inhibited on the unit of the unit, but sometimes the slowing down of this turbine is activated by a moving clutch for the maximum efficient operation of the hydrotransformer in any engine revolutions.
The moving clutches themselves during the movement of the vehicle move the speeds using the connection or disconnection of the components of the "automatic". In particular, here we are talking about the entrance and output shafts and components of the planetary row. Visually, the coupling is something mean between the clutch and the synchronizer in the traditional "mechanics".
This element consists of a drum and a hub, between which the package of ring-shaped moving disks is located. The part of the discs that connects with the drum is made of metal, and the one that connects to the toothbuins of the hub, is made of plastic.
The principle of the coupling is to compress the package of these ring-shaped disks by a hydraulic piston, which is located directly in the drum. The transmission fluid is suitable for the cylinder on the pipes located in the drum, shafts and the "automatic" housing.
In turn, the principle of operation of the overtaking clutch is to slip in one direction and in the encins with the transmission of torque in the other. As a rule, such a coupling consists of several rings - external and internal, as well as the devices between them with rollers. Overpric mechanisms are used to reduce the level of blows in moving clutches at the moment of switching speeds.
The transmission of the torque is carried out by increasing the rotor of the motor after switching, as a result of which one of the parts of the planetary row rotates in reverse side. Accordingly, it encloses in the overtook coupling.
The speed box control unit consists of devices that guide the streams of transmission fluid on the pistons of the brake tapes and moving couplings. The provisions of these devices can be set both manually, with the PPC lever and automatic mode. The same automation in such checkpoints can be both electronic and hydraulic:
- hydraulic automation. The principle of its action lies in the use of the pressure ATF ( transmission Oil) From the central regulator, which is connected to the output pulley of the box. Also, this type of control uses the ATF pressure from the gas pedal, which gives it information about the vehicle speed and the position of the gas pedal;
- electronic automation. Such a type of management uses solenoids, the principle of operation is to switch spools. Wires from solenoids are connected to the control device. Thanks to the "brains", there is a move on the basis of data on the position of the gas pedal and the total velocity of the machine.
Modes "Automat"
Automatic gearbox does not have actual speeds to switch, but its device provides operating modes that we will look at:
- "N" - neutral speed. It is usually operated by the owners of vehicles during towing or when stopped not for a long time;
- "D" - the position of movement forward. At this point, all steps are used in the automatic transmission;
- "R" - reversible movement. This transmission is needed to move the auto rear. This provision cannot be included if the car has not completely stopped;
- "L" - the position of reduced speed is often used to move rolling;
- "P" is the position included on the automatic transmission during the parking for blocking the drive wheels. Here it should be noted that this position of the "automaton" is not connected with the manual brake.
These were the main automatic transmission regimes. There are also additional, which are found on many cars:
- O / D is the position of movement that provides for the possibility of switching to a more enhanced transmission automatically. Such a regime is usually included while driving at high speed;
- "D3" - the position of the box, in which the automatic transmission can use only one of the first three transmissions or disable elevated speed. In this position it is convenient to ride in urban environments and in traffic conditions;
- "S" - the position of automatic transmission when driving at low speeds;
- "L" - automatic transmission mode in which only the first transmission works.
Video "Automatic CAT repair"
This video describes the automatic transmission repair process at the maintenance station.
Did you use this video? Maybe you have something to add an automatic box? Leave your comment!
Article Video How does the gearbox work automat? What are all the advantages and charming management of a car with an automatic box, how reliable and durable automatics, what can I do and what you can not do if you have a box automatic, and is it really automatic transmission Such "stupid" as they say about it or will it be able to "make" a car on the mechanics and leave him 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 elements, then everyone can perform free movement, and 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.
In this case, the external dimensions of the design will change insignificantly. Such properties and determined the use of planetary mechanisms in the automatic box.
Gearbox automatic, small video on the subject 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
The working fluid in the gearbox hydraulic system automatic - ATF oil provides lubrication, cooling, gear shift and a transmission connection with the engine. As a rule, oil in the box is in the crankcase.
Because Oil volume during operation ACPs changes, it is connected to atmospheric air through probe.
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.
And B. real lifeAnd in the virtual space there is an eternal argument between owners of cars with automata and manual gearbox. This dispute is also infinite as the one that is primary: an egg or chicken. Without joining it, we will try simply to simply fill certain gaps in the knowledge of those beginners of car owners who have an automatic transmission.
What is she, "Automatic" box?
We have such types of automatic transmission as Tittronic and Stratonic. A few words about these generally accepted names.
Tiptronic - This is an automatic transmission with the possibility of manual gear shift. In the manual control mode, the driver is handdated by a manual transmission selection by pushing the selector lever towards "+" or "-".
Steptronic -Automatic transmission used in BMW. It also has the possibility of manual gear shift, but the switching speed is increased, and comparable to the manual transmission. In the Startonik, the lever moves along the positions P, R, N, and D. In addition, there is a "m / s" position here, which in the Sport mode holds the transfer until the maximum speed is reached, then the transfer occurs .
How does an automatic transmission work?
The automatic hydromechanical gearbox in the classic version consists of planetary gearboxes, a hydro-industry, overtaking and friction clutches, connecting drums and shafts.
Without going into the debres, it is strongly not recommended to do it, the principle of operation of the automatic transmission is different in that the gear shift occurs due to the interaction of planetary mechanisms and a hydromechanical drive using electronic actuating devices.
Features of operation of the automatic transmission has already been covered on the pages of the site. But we will repeat.
- Box - automatic before starting the movement requires careful warm-up, especially in winter.
- It is not recommended to translate the selector lever on the go to the position P and R.
- There is no need to include neutral when descending from the mountain, saving fuel (as it is considered) will not, but braking problems may arise.
- Motor braking is not carried out in all modes. In more detail about the operation in various modes, the manufacturer gives instructions in the manual. With all our disadvantages, it is advisable to stick to these instructions. First of all, this is, and in the second, not the last - this is the cost of repair or full replacement gentle and sensitive aggregate - automatic transmission
Well, in fact, you can start, warming and start moving.
Good luck to you, lovers of their car.
