Cars increased passibility Have various designs of the full drive systems. Each of them has its advantages and shortcomings. We will talk about the system of the plug-in full drive, or as it is also called part-time. What is her "trumps" and basic "minuses"?
PART-TIME full drive system
main feature drivepart -time. It is that when moving along ordinary roads with a solid coating, only one axis is involved. In fact, in this mode, the machine remains a monoprifer. The second axis can be connected if necessary, in case of need for overcoming off-road.
For connecting the second axis, the distribution box is served. As a result, when such a transmission operates in all-wheel drive mode, a rigid connection between the front and rear wheels is carried out, as well as the distribution of the moment between them in the 50:50 ratio. This is a scheme of classic SUVs. And it should be noted, such a type of transmission, if necessary, overcoming heavy off-road is very effective.
But there is u drivepart -time. and substantial "minus". The tough connection between the axis can be used only on the coatings that enable one of them to slip. This is gravel, ice, sand, dirt, etc.
The fact is that with a tight connection of bridges, there is such a phenomenon as a power circulation. Moreover, if the machine is moving through a solid asphalt coating, it can have very large values. This circulating capacity does not participate in overcoming the forces that impede the movement of the machine, thereby even more loading gears of transmission and tires.
(TYPOGRAPHY PRE_RED) and what as a result? (/ typoography)
As a result, the PART-TIME full drive system is suitable for either asphalt roads, or for frank off-road. It is absolutely not adapted for movement on roads with changing properties of the coating (asphalt with ice stains, solid primer with mud puddles, etc.).
Therefore, today the part-time drive has practically survived itself and does not apply in the automotive industry. It can only be found on old cargo all-wheel drive cars or classic all-terrain vessels.
Part-time drive
The all-wheel drive car has always been considered more powerful, it is enough to remember the SUVs of BMW, Mercedes and Toyota companies. But with time four-wheel drive Appeared and on ordinary machines. Volkswagen installed 4motion system.
What is 4motion
In the 4Motion drive, the torque is usually distributed from the car unit on the wheels of the wheels depending on the situation on the road. It often happens that the road goes passable, and a plot with a marsh or other obstacle comes across, then you need a four-wheel drive. Your history of the first installation on the Volkswagen cars of the 4Motion system begins since 1998. Such a system is installed on both Class cars Sedan, Hatchback and SUVs and crossovers.
Among these cars, Volkswagen should recall Golf IV, V generations, minibuses Volkswagen Transporter and crossover Volkswagen Tiguan.. Now we will look more about the 4motion full drive system.
What is the four-wheel drive 4motion
The name itself is a four-wheel drive 4motion, suggests that the system will not be simple. Each part performs the work allotted. The visual scheme of the 4Motion system shows that the full drive of Volkswagen cars consists of: car unit (1), distribution (2), cardan transfer (3), Cardan (4), inter-wheeled differential For the rear axle (5), the coupling of the rear axle (6), an inter-wheeled differential for the front axle (7) and a car gearbox (8).
Consider the principle of the device of individual components and the purpose in the 4motion system. The first on the list of work will go differential the front axle. Its assignment is the transmission of torque on the leading front wheels from the gearbox. The same housing is connected to a handout.
Further, the list is a handouting box, because of itself is a conical transmission. Thanks to it, the torque is transmitted at an angle of 90 °. The friction clutch and distribution are connected to the cardan transmission from the rear axle drive.
The cardan transmission is two shafts connected between hinges of equal angles of speeds. The trailers themselves are attached to the friction clutch and handout with the help of elastic couplings. As can be seen in the diagram above, the rear cardan shaft has an intermediate support.
In full drive company Volkswagen system 4motion is used multidisk friction clutch called Haldex. Due to it, the torque is transmitted from the front axle of the machine. The degree and magnitude of the transmission of the torque depends on the degree of closure. As a rule, in the 4Motion system, the coupling is built into the rear axle differential carket.
The 4Motion system uses a coupling fourth generation, most often it can be found on the Volkswagen Tiguan crossover. In comparison, C. previous generation couplings she has more simple design. Couplings of the first and second generation can be found on vOLKSWAGEN cars IV and V, as well as on the Volkswagen Transporter.
Construction itself haldex couplings consists of several friction discs, Pressure battery, pump and control systems. Package disk package consists of a set of steel and friction discs. Internal engagement with the hub have only friction discs, steel wheels have engaged with a drum. From the number of disks in the 4Motion system will depend on the value of the torque that is transmitted. As they say, the more drives, the greater the torque will be. In turn, discs are compressed by pistons.
Haldex Coupling Management 4Motion Systems is e-mail, the input sensors are included here, the electronics control unit and the actuators themselves are included. The oil temperature sensor is used as an input sensor.
The task of the 4Motion full drive control unit, as in other car systems, is the conversion of incoming information and transmitting signals to actuators. In addition to the information obtained from the oil temperature sensor, the control unit pulls information from the car unit control unit and aBS systems.
The 4Motion executive devices include the control valve, it is capable of adjusting the pressure of the compression of the friction discs ranging from 0 and to 100% of the possible magnitude. Due to the position of the valve, the pressure value is determined. As for the pressure accumulator and pump, they provide support for oil pressure throughout the 4Motion system at 3 MPa.
As we can see the 4Motion full drive system from Volkswagen is not quite complex in comparison with other manufacturers. The Volkswagen manufacturer began to install on various models His cars, thereby increasing comfort, handling and reliability.
How the 4Motion system mechanism works
The operation of the 4Motion full drive system depends on the algorithm of the control unit and Haldex couplings. As a rule, the following work algorithms are distinguished:
- start of movement;
- slobing at the beginning of the movement;
- movement at constant speed;
- movement with frequent slippers;
- sharp braking.
If the 4Motion algorithm is taken when the front wheels are started at the start, the control valve will immediately close, and the clutches friction discs will be freezed. In this case, the torque will be completely transmitted to the rear axle. Relative to the front wheels, then one of the wheels in the process will be connected or disconnected using electronic block Differentials of the 4Motion system.
Taking as the basis of the 4Motion operation, when the car moves at a constant speed, the valve will be open, and the discs will be compressed depending on the conditions of movement and road surface. Torque on the back axis will be transmitted only at the most necessary moments, and mostly the entire load will go to the front axle.
The following 4Motion slip algorithm, during the movement of the vehicle, is calculated based on the signals received from the ABS system control blocks. The valve will be discussed depending on the conditions of the car movement. The control unit will watch which axis and which wheels are buxes, on those and transmit torque.
The last version of the 4Motion work is when the car slows down. In this case, the control valve will be open, and the friction clutches are completely osculated. Not depending on the situation, torque when braking on the rear axle will not be transmitted.
Video Principle of Haldex Coupling on 4Motion:
Transmission design all-wheel drive car Provides the ability to transfer torque to all four wheels. Different schemes make it possible to realize the entire potential of power, manageability and active car safety, depending on its purpose. All-wheel drive transmission can be denoted by 4x4, 4WD or AWD abbreviation.
Advantages of a full drive
The advantages of a car equipped with a all-wheel drive transmission is easy to understand based on the disadvantages of a mono-drive car, which drives only on one axis (front or rear), i.e the drive wheels or front or rear.
All-wheel drive car on off-road
The use of free on the main mass budget cars In difficult road conditions, makes the leading actually one wheel, which has a worst clutch with the surface of the road. This feature of the work of differential. And even if both wheels have a sufficient adhesion with an expensive, excessive power supply often leads to their slip, loss of control or jams of the car. These are minuses of monolon, which are especially visible on slippery road covering and off-road. In order to eliminate these disadvantages, manufacturers use self-locking interstole differentials.
However, the optimal solution is to make all the wheels leading, improving and adding the transmission design with the necessary components. Full-wheel drive provides the car the following advantages:
- increased permeability;
- improved clutch with expensive when starting on slipping coating;
- course stability and predictable behavior on a slippery road.
Elements of all-wheel drive transmissions
All-wheel drive transmission All-wheel drive transmission of the car consists of the following main elements:
- mechanical or automatic transmission;
- handout or multid-wide coupling;
- inter-seed differential;
- cardan transmission;
- rear and front differentials;
- control elements.
Types of complete drive
Permanent full drive
Permanent four-wheel drive 4x4 is the type of actuator at which the torque is distributed from the engine at the same time on all the wheels. Such a drive can be used at different classes of vehicles with a longitudinal or transverse engine location scheme. For optimal torque distribution modern systems The full drive is equipped with self-locking differentials with the possibility of distributing power over the axes in different ratios.
Elements of constant full drive system Quattro Electronics coordinates system operation, receiving signals from wheel speed sensors, and instantly changes the power ratio depending on road Conditions and the nature of the movement. This type The full drive is the most progressive system that provides the best. active security and driving dynamics.
Disadvantages: increased flow Fuel and constant load on transmission elements.
The branded permanent four-wheel drive to all the wheels use in their cars manufacturers such as Audi (), BMW (), Mercedes () and others.
Forcibly connected
For high-pass vehicles, the optimal method of implementing the full drive is forcibly connected. It is arranged according to the standard scheme, there is only a central differential. The main axis is the rear, plug-in - front. The torque on the front axle is transmitted by means of a dispensing box, which is manually controlled.
Scheme and elements of the connected full drive The driver independently includes the drive of all the wheels by means of levers or control buttons before overcoming a complex area or, for example, off-road. The inclusion of a dispensing box provides a rigid connection between the axes and the distribution of the torque in an equal ratio. On the dashboard The full drive indicator lights up. Often, the design additionally provides for the possibility of tight blocking of inter-wheeled differentials, as well as the use of increased and reduced gears.
With the full drive enabled, the transmission elements are experiencing strong loads, car handling significantly deteriorates. In normal conditions, the movement is turned off, and the entire drive indicator goes out, the movement continues with the rear axle. Transmission is released, which provides the extension of its resource and reduce fuel consumption. Forcedly connected four-wheel drive applied, mainly on SUVs. For example, on Toyota Land Cruiser. and Land Rover. Defender.
Automatically connected
Diagram of automatically connected full driveThe circuit of the automatically connected full drive is designed to meet the possibility of instilling the second axis to the master. Main drive - rear or front. When fixing the difference in the rotation of the wheels, the friction clutch of the inter-axis differential closes over the electronics command, and the power begins to be transmitted to all the wheels. A number of models involves the disabled mode of 4x4, and the car becomes a monolayer. Automatically connected 4Motion full drive system is used on Volkswagen autocontracene models.
Application of various full drive systems
Depending on the class and destination of cars apply different kinds full drive most suitable on their working and performance characteristics.
For premium cars, where, first of all, comfort, handling and safety, optimal option - Permanent four-wheel drive under the control of control electronics. Suite SUVs combine the permanent four-wheel drive and forcibly connected four-wheel drive with the possibility of tight blocking of differentials. The operation of the full drive system monitors and regulates the electronics. If necessary, the driver includes hard lock if, for example, you need to leave dirt.
Many lovers active rest and frequent trips are chosen as vehicle Crossovers and SUVs, in the design of which is used four-wheel drive. Such cars are distinguished by increased clearance and all the leading wheels, which ensures good permeability.
But not always such cars are able to overcome even the middle off-road, not to mention serious mud. And it may turn out to be all the same four-wheel drive, more precisely. constructive features. Therefore, the presence of all leading wheels does not mean that the machine is capable of conquering strong dirt.
Major composite elements of transmission
Four-wheel drive implies torque transmission from power aggregate On the wheels of both axes, thanks to which the passability of dirt increases.
The main constructive feature of the actuator of this type in front of others (front, rear) is the presence in the transmission of an additional node - a dispensing box. It is this node that provides the distribution of rotation on two axes of the car, making all the wheels leading.
In general, this car transmission consists of:
- clutch;
- gearbox gearboxes;
- dispensing box;
- drive shafts;
- the main transfer of both bridges;
- differentials.
Embodiment of the all-wheel drive transmission (connected automatically)
Despite the use of the same components, variations and constructive performances Transmissions - set.
Constructive and operational features
It is worth noting that on many auto drive on all the wheels is not always carried out. That is, the leading is constantly only one axis, the second is connected only if necessary, and it can be done as in automatic modeand manually. But there are also transmission variations, which does not exit the axis.
Transmission with a design that transfers rotation to all wheels is used on a car both with a transverse installation of a power unit and with longitudinal. At the same time, the layout predetermines which of the driving axes constantly functions (the exception is a permanent four-wheel drive).
The system that provides the drive to all wheels can work both with the manual transmission and from any automatic box Transmissions.
The principle of operation of the system is simple enough: the rotation from the motor is transmitted to the checkpoint, which provides a change gear ratios. From the gearbox, rotation enters the distribution, which redistributes it into two axis. And then already cardanian Valam Rotation is transmitted to the main programs.
But above describes the overall concept of the full drive system. Structurally, the transmission may differ. So, as a rule, on a car with a transverse location in the design of the checkp and main gear front Bridge, and razdatka.
But in the car with the engine installed longitudinally, distribution and the main transmission of the front axle - individual elements, and the rotation of them comes through the drive shafts.
There are still a number of constructive features that directly affect the passability of the car. First of all it concerns a transfer box. In full-fledged SUVs, this node necessarily has a lower transmission, which is not always in crossovers.
Also on off-road qualities Differentials affect. The amount of them may be different. In some auto there is an interstitial differential, which is included in the dispensing device. Due to this element, it is possible to change the ratio of the distribution of rotation between the axes depending on the conditions of movement. In some cars, it also provides for the blocking of this differential, after the involvement of which the rotation distribution over bridges is made in strictly specified proportions (60/40 or 50/50).
But the inter-axis differential in the design of the system may not be. But the inter-wheeled differentials installed on the main gears are present on all cars, but not all of all their locks. This also affects the driving qualities.
Drive control mechanisms are also distinguished. In some cars, everything is done in automatic mode, others have the driver for this electronic systemsThirdly has a fully manual connection, mechanical.
In general, the four-wheel drive used on the car, the system is not so simple, as it originally seems, although the principle of its functioning on all cars is the same.
The most famous are systems:
- 4Matic from Mercedes;
- Quattro from Audi;
- xDrive from BMW;
- 4motion concern Volkswagen;
- Attesa Nissan;
- VTM-4 HONDA companies;
- ALL WHEEL CONTROL MITSUBISHI Development.
Types of drives used on cars
On cars, three types of total drive, differing from each other both constructively and on features of work:
- Permanent full drive
- With automatically connected bridge
- With manually connected
These are the main and most common options.
Types of complete drive
Permanent drive
Permanent four-wheel drive (international designation - " full Time."), Perhaps, the only system that is used not only on crossovers and SUVs, as well as universities, sedans and hatchbacks. It is used on a car with both types of layout layout.
The peculiarity of this type of transmission is reduced to the fact that the shutdown mechanism of one of the axes is not provided. In this case, the dispensing box may have a lower transmission, the inclusion of which is forced using an electronic drive (the driver simply selects the descriptor the required mode, and the servo drive performs switching).
Selector selection reduced transmission and traffic intensity depending on the area
It is used in its design with an inter-system differential with a locking mechanism. IN different types Transmission blocking can be carried out by an ussociation, a multi-disc clutch of friction-type or differential Torsen. Some of them perform blocking in automatic mode, others are forcibly, manually (using an electronic drive).
Inter-wheeled differentials in the system of permanent full drive are also equipped with locks, but not always (on sedans, universities and hatchbacks it is usually no). Also, it is not necessary to lock at once on two axes, often such a mechanism is installed only on one of the axes.
Drive with automatically connected axis
In a car with automatically plug-in bridge (designation - " ON DEMAND."), Four-wheel drive is included only under certain conditions - when the wheels of the permanent axis began slipping. During the rest of the time the car is anterior (with a transverse layout) or rear-wheel drive (in case the engine is located longitudinally).
Such a system has its own design features. Thus, the dispensing box has a simplified design and a lower transmission in it is not, but it provides a constant distribution of torque over the axes.
There is also no interstreen differential, but there is a mechanism for the automatic connection of the second axis. It is noteworthy that the design of the mechanism uses the same nodes as in the inter-axis differential - the Viscounts or a frictional coupling with electronically control.
The feature of the operation of the drive with an automatic connection is that the distribution of the torque over the axes is made with different ratios, which changes under different conditions of movement. That is, at one mode, rotation is distributed in proportion, for example, 60/40, and with a different - 50/50.
At the moment, the system with automatic connection of the full drive is promising and uses many automakers.
Manual transmission
Transmission with a plug-in manual mode (designation - " Part Time.") Now it is obsolete and used not often.
Its feature is that the connection of the second bridge is carried out in the dispensing box. And for this, it can be used as a mechanical drive (by means of a distribution control lever installed in the cabin), and the electronic (the driver uses the selector, and the servo is connected / disconnecting the bridge).
In such a transmission, there is no inter-axis differential, which ensures a constant ratio of the distribution of the torque (usually in the proportion of 50/50).
Almost always in the inter-wheeled differentials, blocking is used, and forced. These design features provide the largest auto traffic recordings.
Other options
It is worth indicating that there are combined transmissions that are inherent in constructive and operational features At the same time several types of systems. They received the designation " Selectable 4WD."Or multi-mode drive.
In such transmissions, it is possible to install the drive mode. Thus, the connection of the full drive can be carried out both in manual and automatic mode (and there is the possibility of disconnecting any of the bridges). The same applies to the distillations of differentials - inter-axes and inter-track. In general, variations of the operation of the transmission are many.
There are more interesting options, for example, an electromechanical four-wheel drive. In this case, the entire torque comes only on one axis. The second bridge is equipped with electric motors, which are activated in automatic mode. Recently, such a transmission is becoming increasingly popular, although a full-fledged system, in a classical understanding, cannot be called it. Such cars are hybrid systems.
Positive and negative sides
Four-wheel drive has a number of advantages over other types. The main ones can be allocated:
- Efficient use of power supply power;
- Ensuring the improved controllability of the car and its coursework on different types of coating;
- Increased cargo car.
Counterweight advantages are such negative qualities as:
- Increased fuel consumption;
- The complexity of the design of the drive;
- Large metal transmission.
Despite negative qualities, cars that have four-wheel drive are in demand and are very popular even among motorists, for the city almost never traveling.
AUTOLEEK."Honest four-wheel drive" is not quite clear, but a convincing term, sacred mantra of the Internet guru. However, today the overwhelming majority of manufacturers makes a bet on electronics and multi-disc clutches, automatically plugging the rear axle ...
Well have in case of assault snow-drift Machine with wheel formula 4x4, and the rest of the time is an economical monol. And when attaching from a place on a wet asphalt, it is useful to be fulfillment. But after a moment, when the speed is typed, the depriving axis is only the overrun of fuel.
This is a 100% crossover format, and in order to become possible quick or short-term inclusions of the second pair of leading wheels, a variety of multi-disc couplings of their connection appeared.
Metal and fuel economy
The inexpensive and compact multi-line clutch, which does not cause additional vibrations and is extremely responsive, outed today by 90% of all-wheel drive machines All other types of transmission, which reduces the formula of the current building of the mass crossover to a single principle: the transversely located in front of the motor constantly leads the front wheels, and the rear is connected to the coupling needs.
Four-wheel drive, thus implemented, much easier than real off-road structures. Dispensing box No, only an additional pair of power take-off gears remain near the front differential. Another plus: thanks to low weight and sizes it became possible to unload a clutch from the severity of the already heavy front of the car. Multidisk coupling settled right on the rear gearbox.
DIFFERENT
But the clutch couphe is dispersed. With the same principle of connecting a second construct bridge, significant differences may have significant differences.
Initially, it was decided to somehow force the coupling from slipping the front halves associated with the engine and front wheels, relative to the rear connected with the rear wheels. Slauxed before, the difference between the revolutions of halves, the coupling was blocked, the ass was connected. Logical?
The very first couplings used Volkswagen Golf. In its transmission syncro. The friction package in them was not compressed, but was flooded with silicone fluid, which was thick with large loads and the spin itself. It was impossible to manage such a visco-clutch, the characteristic of its work left much to be desired, and 100% of the torque on the rear wheels could not pass. In addition, when squinting in the mud, Silicon boiled, the clutch was quickly overheated and ... burned.
Another design hit early Ford Escape.. There, the coupling discs were already compressed, but it happened purely mechanically, with the help of balls and wedge-shaped slits, at the time of turning the front of the front. The coupling worked clearer, but sharp, causing unexpected strikes in the most responsible phase of slippery turn.
Imagine that in the prience, your car suddenly will turn out of the front-wheel drive to the "classic", and the clutch gas dumping will also suddenly turn off. The consequences can be fatal.
This problem and further pursued the couplings for quite a long time. To adequately adjust the power flow to the rear wheels, and at the same time protecting the discs of the coupling from overheating, an attempt was made to use hydraulics.
Coming Haldex
The latest version of the uncontrolled coupling was the first generation of Haldex 1998. Here the discs compressed the hydraulic cylinder, the oil pressure for which produced the pump. The pump was mounted on one half of the coupling, and the drive came from another. That is, now with the difference of turns of the front and rear wheels The compression pressure and the coupling was blocked. Haldex worked gently and turned out to be successful.
Two winters received at once: the oil, now circulating and through the hydraulic pump, was better cooled, and the hydraulic factory is clearer and, most importantly, it worked faster. But still remained unused part of the drive functional - the control of the connection rear bridge At the very beginning of the development of a dangerous situation, partial blocking of the coupling for turning. Electronics could have been able to cope with this.
So in 2004 there was a second generation of Haldex all with the same discs and pump, but with an electronic valve, and the machine stabilization system was introduced into the brains, headed by a full drive.
Compact. The entire set of Haldex coupling elements is assembled into a dense unit and in dimensions only a little more standard differential
The system has become managed, and the transmitted torque stopped directly dependent on the difference in the speeds of the front and rear wheels.
FOREWARNED IS FOREARMED
Everything is good, but remained "unaffected" situations in which it would be nice to get a full-wheel drive before slipping the front wheels. In other words, the pump, which operates from the difference between the turns of the coupling halves, was no longer suitable for transmission engineers. After all, its saving pressure in some motion modes was simply absent.
The decision was simple and in general features It is applied to this day in most of the airborne coupling.
The next is the fourth - the generation of Haldex received the electrical pump attached outside and already familiar to us adjustment valves in front of the hydraulic cylinders. Now at any time the coupling could be completely or partially closed only by the signal of the electronics.
This principle gave a lot positive effects. The start modes appeared from the place where the coupling for a short period of acceleration is completely blocked. Added modes of essential lock in turns when good grip On dry asphalt allows you to use four-wheel drive to the entire coil.
No matter how surprisingly, all-time qualities have increased. After all, it became possible to simply press the button to switch the clutch algorithm to the "asphalt" on-road or entrust this business automation.
Learn the three main modes of the transmission of your crossover? Of course, you exactly have such a coupling in the rear wheel drive!
Only a moment. Two components of the speed of the system - the electronic brain and the ultrafast electric valve, the opening time of which is less than 0.1 with
FURTHER MORE
Electronic coupling control has become conveniently combined with a stabilization system, and with the program of the frictional safety program. A small thermal sensor inside the coupling from now on watched the operating temperature and disconnected the drive if the frictional overheating was close. Of course, the car that became ten minutes can take out of equilibrium, but it is incomparably better smoke from the bottom and breakdowns of the transmission.
In addition, the more crossovers with electron-controlled couplings turned out to be in the hands of the owners, the wider and more accurately became the programs of the full drive systems. Today, the best of them are no longer afraid of overheating not only in loose snow, but also with frank mud bucks. And also chemists with materials did not sit back. New disks and lining materials allowed twice the temperature emergency shutdown, as well as increase the moment-transmitted torque to the values \u200b\u200bof knowingly large than the motor can give.
Modern friction materials, high-quality oils And advanced disk closing control programs make it possible to even keep the clutch partially connected without fear of its overheating. The car receives the distribution of torque over the axes in the proportion of 10:90, and then and 40:60, which for brands, with a rear-wheel drive layout, allows you to combine the classic habits on the road with a light all-wheel drive, sometimes almost imperceptible. And even continuously vary the degree of connection, improving the controllability of the machine and helping the stabilization system to do its job.
Given the flexibility of the work algorithms and the high degree of resolution of the construction of multi-disc couplings, today it is the most massive version of the organization of a full drive and is hardly in the foreseeable future we are waiting for something fundamentally new.
