Subaru celebrates 40th anniversary of its all-wheel drive vehicles
Fuji Heavy Industries Ltd. (FHI), the manufacturer of Subaru vehicles, announced that 2012 marks the 40th anniversary of the debut of Subaru all-wheel drive vehicles, the first of which, the Subaru Leone Estate Van 4WD, was introduced in Japan in 1972.
To this day, FHI remains a pioneer in the field of all-wheel drive passenger cars. The total number of Subaru all-wheel drive vehicles *1 produced reached 11,782,812 units (as of January 31, 2012), representing approximately 55.7% of the brand's total sales.
Complete system Subaru drive ensures efficient distribution of traction force over all four wheels. Thanks to the combination of symmetrical all-wheel drive (SAWD) and horizontal boxer engine Subaru Boxer, power unit is located symmetrically relative to the longitudinal axis of the car, and the transmission is shifted back, within the wheelbase. This arrangement optimizes the longitudinal-transverse mass balance and ensures stable traction on any surface. different conditions movements. In addition, excellent stability is achieved high speeds And excellent characteristics cornering and steering response, making SAWD the core technology that underpins Subaru's philosophy of safety combined with driving enjoyment.
Through continuous research, tailoring Subaru's all-wheel drive system to each model, FHI has perfected its technology in this area - from technology capable of providing handling on rough roads to unique technology, which guarantees high stability in rain, snow or high-speed driving conditions. Latest developments include four-wheel traction control, which creates constant reliable grip all four wheels with the road.
Additional Information
Subaru Symmetrical All-Wheel Drive Systems
- VTD all-wheel drive system *2: Sports version all-wheel drive with electronically controlled, improving turning characteristics. The compact all-wheel drive system includes a center planetary differential and an electronically controlled multi-plate hydraulic lock-up clutch *3. Torque distribution between front and rear wheels 45:55 ratio is continuously adjusted by differential locking using a multi-plate clutch. Torque distribution is controlled automatically, up to a 50:50 ratio between the front and rear wheels, taking into account road surface conditions. This provides excellent stability, and due to the distribution of torque with an emphasis on rear wheels Steering characteristics are improved, resulting in aggressive, sporty driving.
Current models (Russian specification)]
On Russian market Subaru Legacy GT, Forester S-Edition, Outback 3.6, Tribeca, WRX STI with automatic transmission - All-wheel drive system with Active Torque Vectoring (ACT): Electronically controlled all-wheel drive system improves efficiency and stability. Original multi-plate torque transmission clutch moment Subaru Electronically controlled, it adjusts the torque distribution between the front and rear wheels in real time according to driving conditions. In normal modes, the system distributes torque between the front and rear wheels in a ratio of 60:40. It makes the most of all-wheel drive, providing stable and safe handling in any situation. traffic situation, regardless of the driver’s level of training.
On the Russian market Subaru Legacy/Outback 2.5 with Lineartronic transmission, Forester (with automatic transmission), Impreza and XV with Lineartronic transmission. - All-wheel drive system with center limited-slip differential with viscous coupling (CDG): Mechanical all-wheel drive system for manual transmissions. The system is a combination center differential with bevel gears and viscous coupling-based locking. Under normal conditions, torque is distributed between the front and rear wheels in a ratio of 50:50. The system ensures safe, sporty driving, always making the most of the available traction.
[Current models (Russian specification)]
Subaru Legacy, Forester, Impreza and XV with manual transmission. - All-wheel drive system with multi-mode center differential (DCCD *4): All-wheel drive system designed to provide maximum performance driving characteristics, for serious sports competitions. The all-wheel drive system with electronically controlled active limited slip center differential uses a combination of mechanical and electronic locks differential when changing torque. Torque is distributed between the front and rear wheels in a ratio of 41:59, with an emphasis on maximum driving performance and optimal control dynamic stabilization car. Mechanical locking has a faster response and operates before electronic locking. Operating with high torque, the system demonstrates the best balance between control acuity and stability. There are preset differential lock control modes, as well as a manual control, which the driver can use according to the traffic situation.
[Current models (Russian specification)]
Subaru WRX STI with manual transmission.
*1 including production of vehicles with all-wheel drive
*2 VTD: Variable torque distribution
*3 Controlled limited slip differential
*4 DCCD: Active center differential
Symmetrical AWD
Symmetrical all-wheel drive
Since its introduction in 1972, Symmetrical AWD technology ( All- Wheel Drive) has been continuously improved. Complemented by horizontally opposed Subaru engine BOXER, it ensures a perfectly symmetrical design. This ensures maximum efficiency of engine power delivery, high level road grip and vehicle stability, as well as ideal weight distribution. Absolute control above the car is maintained in almost any driving conditions, turning every kilometer of the road traveled into a pleasure.
The engine's torque is constantly transmitted to all four wheels and provides maximum traction and, consequently, maximum vehicle controllability, therefore, the better the traction of the wheels, the more confident you feel behind the wheel of your car. This advantage- Your key to success in extreme conditions, be it bad weather or emergency situation, when the count goes down to a fraction of a second.
Advantages
Better balance
When you turn, centrifugal force pushes the car toward the edge of the road. How far a car skids depends on its center of gravity. If it is positioned high, it takes longer to regain balance and control of the vehicle. When low - like the Subaru - there is less body roll and less yaw, giving the car more stability.
Improved grip strength
Constant four-wheel drive has special advantages over 2-wheel drive (2WD) - especially when cornering. By transmitting power through all four wheels, the vehicle steers naturally and neutrally when cornering, avoiding the sluggishness or oversteer that can lead to instability and accidents.
Although all all-wheel drive systems of Subaru vehicles have the same designation and name, today there are several different versions of the Subaru AWD all-wheel drive implementation.
All Subaru models, excluding the rear-wheel drive Subaru BRZ coupe, are equipped with standard Subaru AWD symmetrical all-wheel drive. But despite the common name, there are at least four different all-wheel drive systems in use today.
Standard all-wheel drive system based on a center self-locking differential and viscous coupling (CDG)
This is the system that most people associate with all-wheel drive. Found in most Subaru vehicles with manual transmission. It is the most symmetrical of all four-wheel drive configurations, with torque split between the front and rear in normal driving conditions. rear axle 50:50.
Subaru cars like Subaru WRX 2011 with manual box gears have an all-wheel drive system based on an interaxle self-locking differential and viscous coupling
When front or rear wheel slip is detected, the center differential can send up to 80 percent of the torque to the axle that has the best traction. The center differential uses a viscous coupling that operates without computer control and responds to mechanical differences in wheel grip.
This type of AWD system has been around for a very long time, and its appearance on the 2015 Subaru WRX means it's probably here to stay. soon. This one is simple reliable system is the workhorse of Subaru's AWD system. The system ensures safe, sporty driving, always making the most of the available traction.
An all-wheel drive system based on an interaxle self-locking differential and viscous coupling can be found on Subaru Impreza 2014 2.0i trim, on 2014 XV Crosstrek with 5-speed manual transmission gears; on Subaru Outback 2014, Subaru Forester with a 6-speed manual transmission and the 2015 WRX with a 6-speed manual transmission.
All-wheel drive system withvariable torque distribution for vehicles with automatic transmission (VTD)
Subaru recently began converting most of its vehicles from standard torque-converting automatic transmissions to continuously variable transmissions (CVT).
Legacy, Outback, and Tribeca with the powerful 3.6-liter engine use the vehicle's Variable Torque Distribution All-Wheel Drive system
but there are still cars using this system.
A version of symmetrical all-wheel drive using variable torque distribution (VTD) is used on Legacy, Outback, Tribeca with six-cylinder engine volume of 3.6 liters and five-speed automatic transmission transmission In this case, the default torque distribution is 45:55 with a shift to the side rear axle, and instead of a center differential with a viscous coupling, a hydraulic multi-disc clutch is used in combination with a planetary type center differential.
When slippage is detected, based on signals received from sensors measuring wheel slip, the position throttle valve and braking force, the electronically controlled clutch can lock a 50:50 split (of torque) between the front and rear axles where maximum traction is required.
While a purely mechanical viscous coupling is simpler and perhaps more flexible, an electronically controlled VTD system has the advantage of being active rather than reactive, moving torque between axles faster than otherwise possible mechanical system.
All-wheel drive system with Active Torque Vectoring (ACT)
With the transition to CVT, Subaru models such as the XV Crosstrek also switch to AWD systems with a slight bias towards the front axle
Newer Subs equipped with a CVT system now use a third version of the all-wheel drive (AWD) system. This all-wheel drive system is similar to the VTD system described above - both use an electronically controlled multi-plate clutch to control torque, but CVT systems distribute torque 60:40, biased towards the front axle.
This all-wheel drive system is also called AWD with Active Torque Vectoring (ACT). Subaru's original electronically controlled multi-plate torque clutch adjusts the torque distribution between the front and rear wheels in real time according to driving conditions.
The use of this system improves the efficiency and stability of the vehicle. You can find this system on XV Crosstrek models, new Forester 2014, new WRX and WRX STI 2015, and older models such as Legacy 2014, Outback 2014.
All-wheel drive system with multi-mode center differential (DCCD)
In addition to the all-wheel drive systems described above, Subaru cars Other variants of symmetrical all-wheel drive were also used, which are no longer used. But latest system The one we'll be mentioning today is the system found on the WRX STI.
Directly below the SI-Drive knob is a switch that allows WRX STI drivers to change the balance between the two center differentials
This system uses two center differentials. One is electronically controlled and provides on-board computer Subaru good control over the distribution of torque between the axles. The other one is mechanical device, which can respond more quickly to external influences than its electronic “colleague”. The driver's benefit here, ideally, is to have the best of the electronically proactive and mechanically responsive 'world'.
Generally speaking, these differentials naturally exploit their differences - being harmoniously united by a planetary gear - but the driver can bias the system towards either of the center differentials using electronic system Driver Controlled Center Differential (DCCD) - Driver Controlled Center Differential.
DCCD torque distribution is 41:59, biased towards the rear axle. This is a performance-oriented all-wheel drive system for serious sports competitions.
Lateral torque distribution
So far we have figured out how modern Subaru distribute torque between the front and rear axles, but what about the distribution of torque between the wheels, between the left and right side? On both the front and rear axles you will typically find a standard differential open type(i.e. non-blocking), but more powerful models(such as WRX and Legacy 3.6R models) are often equipped with a limited-slip differential on the rear axle to improve traction on the rear axle during cornering.
WRX STIs also feature a limited-slip differential on the front axle to maximize all-wheel traction, and the latest 2015 WRX and 2015 WRX STI also feature brake-based torque vectoring systems that apply brakes to the inside wheel when cornering to transfer power to the outside wheels. side when turning and reduce the turning radius.
Today there are many known all-wheel drive systems for cars. Let's look at the two most common versions using Subaru cars as an example, because some of them have a common name and designation. There are several different versions implementation of all-wheel drive Subaru AWD.
All similar models (except rear-wheel drive Subaru BRZ coupes) have a standard symmetrical all-wheel drive AWD drive. The name is common, but four of its modifications of all-wheel drive systems are used.
Standard all-wheel drive system based on center limited slip differential and viscous coupling (CDG)
Most people assume that this category of systems is associated with all-wheel drive. It is very common in cars of a similar brand that have a manual transmission. This model is a symmetrical all-wheel drive configuration, under normal conditions the torque is in a 50/50 front/rear ratio.
When the car slips, the differential, which is located between the axles, is capable of sending up to 80% of the torque to the front axle; this function ensures good traction between the tires and the road surface. Viscous coupling is used by such a differential so that it can respond to mechanical differences in tire grip without computer intervention.
You can see the cdg all-wheel drive type on a Subaru Forester with six-speed gearbox transmission
This type of drive has been in use for a long time, and the emergence new version V next year It only means that he won’t disappear anytime soon. The model is reliable and simple system all-wheel drive, which can provide very safe driving when using available traction.
It should be noted that you can see the cdg type of all-wheel drive on the 2014 Subaru Impreza with a two-liter engine, as well as on the XV Crosstrek, which has a five-speed manual transmission, and on the Ouback and Forester, which have a six-speed gearbox.
All-wheel drive system with variable torque distribution for vehicles with automatic transmission (VTD)
It is very important to note that the Subaru concern has begun to transfer most of its Vehicle from standard automatic to continuously variable transmission (CVT). At the same time, now you can still find cars with such a system.
Symmetrical all-wheel drive, which involves the use of variable torque distribution, can be found on the Tribeca (with a 3.6i engine and 6 cylinders, as well as a 5-speed transmission), Outback and Legacy. Here there is a shift in torque towards the rear axle in a proportion of 45 to 55. Instead of a center differential with a viscous coupling, a multi-disc differential will be used here hydraulic clutch, which will be combined with the differential of the planetary version.
When slippage is detected, signals will be sent from sensors that are installed to measure wheel slip, as well as braking force and the position of the valve located near the throttle. In this case, the torque will be distributed evenly along the axles (50 to 50) to ensure maximum adhesion of the wheels to the asphalt surface.
A fully mechanical viscous coupling is much simpler and more flexible. The VTD system has the advantage that it has an active rather than reactive component, this achieves a high speed of torque movement between the axles, a mechanical system cannot boast of this.
All-wheel drive system with Active Torque Vectoring (ACT)
New Subaru models already use a third version of all-wheel drive systems. In particular, it has many similarities with the previous version - it also involves the use of an electronically controlled multi-disc system in a 60 to 40 ratio with a torque shift to the front axle.
The act all-wheel drive type is used on Subaru Legacy 2014 models
This AWD also has active torque distribution, called ACT. Thanks to the original multi-plate clutch transmitting such torque with electronic control, the distribution of torque between the axles in real time corresponds to the conditions of movement of the vehicle.
This all-wheel drive system allows you to increase both the stability and efficiency of the machine. The act all-wheel drive type is used on the Subaru XV Crosstrek, Legacy 2014, Outback 2014, WRX and WRX STI 2015 models.
All-wheel drive system with multi-mode center differential (DCCD)
In addition to the all-wheel drive systems described above, Subaru vehicles also used other symmetrical all-wheel drive options that are no longer used. But the last system we'll mention today is the one found on the WRX STI.
This system uses two center differentials. One is controlled electronically and provides the on-board computer Subaru is good control over the distribution of torque between axles. The other is a mechanical device that can respond more quickly to external influences than its electronic counterpart. The driver's benefit here, ideally, is to have the best of the electronically proactive and mechanically responsive 'world'.
Generally speaking, these differentials naturally exploit their differences - being harmoniously combined by a planetary gearset - but the driver can bias the system towards either center differential using the electronic Driver Controlled Center Differential (DCCD) system.
The torque distribution for DCCD systems is 41:59 with a bias towards the rear axle. This all-wheel drive system is designed to provide maximum performance for serious sports competitions.
Lateral torque distribution
So far we've figured out how modern Subarus distribute torque between the front and rear axles, but what about the distribution of torque between the wheels, between the left and right sides? On both the front and rear axles, you will typically find a standard open-type (i.e. non-locking) differential. More powerful models (such as the WRX and Legacy 3.6R models) are often equipped with a limited-slip differential on the rear axle to improve rear traction when cornering.
WRX STIs also feature a limited-slip differential on the front axle for maximum all-wheel traction. Newest WRX The 2015 and 2015 WRX STI also use brake-based torque vectoring systems that apply brakes to the inside wheel during a turn to help transfer power to the outside when cornering and reduce the turning radius.
At the very beginning of its history, Subaru relied on all-wheel drive versions models produced - technology that at that time was available mainly on special vehicles. In 1972, Subaru introduced its first all-wheel drive model Leone Estate Van 4WD, and since then more than half of the company's sales have been 4WD vehicles. It is also important that Subaru's symmetrical all-wheel drive was not adapted to cars with single-axle drive, but was immediately created for use on cars with four drive wheels. As for the all-wheel drive Subaru Symmetrical All Wheel Drive with axle shafts of the same length, coupled with a longitudinally located opposed Subaru Boxer engine and a transmission shifted within the wheelbase, this arrangement allows, in addition to close to ideal weight distribution along the axles, to ensure efficient implementation of engine power and good clutch balance wheels with the road on any type of surface. That is, optimal distribution of torque between all wheels, which means a high level of controllability.
Torque is optimally distributed to all wheels, resulting in close to neutral steering
Symmetrical all-wheel drive confidently counteracts both the drift of the front axle and the skidding of the rear
Types of complete Symmetrical drive AWD four. The first of them, VTD, is not presented on the Russian market today, but was previously used on the Legacy GT 2010–2013, Forester S-Edition of the same period, Outback with a 3.6-liter engine 2010–2014, Tribeca, 2011–212 WRX and WRX STI This system uses a planetary-type center differential, which is locked by a multi-disc hydraulic coupling with electronic control.
The original 45:55 torque distribution is constantly monitored by Vehicle Dynamic Control and automatically changes depending on the road surface, profile and topography. The second system is ACT with active torque distribution. Here, through a multi-plate electronically controlled clutch, the torque, depending on the road condition, is dosed to the front and rear wheels up to a ratio of 60:40 in real time. The Russian market with this type of all-wheel drive includes Forester, Outback and XV models with Lineatronic transmission.
For manual transmissions, the CDG all-wheel drive system with a self-locking differential is designed. Its design uses a center differential with bevel gears, locked by a viscous coupling. Moreover, under normal driving conditions, the distribution of traction between the front and rear wheels occurs in a ratio of 50:50. This system is very well suited for sporty driving, so it is not surprising that it was previously used on the WRX model with a manual transmission, and today the Forester and XV models with manual transmission are presented on the Russian market. The fourth type of all-wheel drive Subaru - DCCD has an electronically controlled active limited slip differential in its arsenal, and it is completely aimed at fans of sports driving, those who love the Subaru brand for its cars with a racing character.
It is with this type of drive that we present the Subaru WRX STI. This design is a symbiosis of electronic and mechanical center differential locks that respond to changes in torque. The faster one fires first mechanical locking, then the electronic locking is activated. Torque is distributed between the front and rear wheels in a ratio of 41:59, and the operation of the entire system is focused on optimal use of maximum driving characteristics. The design of the differential provides for the possibility of “preload”, that is, a mode for pre-setting its characteristics. By quickly delivering high torque, this system provides a good balance between sharp and precise handling and vehicle stability. Of course, this type of drive also provides manual mode transmission control.
The low center of gravity of the compact boxer engine, symmetrical all-wheel drive with drives of the same length and transmission variations... All this ensures excellent handling on any type of surface.
And in conclusion, a few well-known postulates about the advantages of all-wheel drive. IN in this case symmetrical all-wheel drive Subaru Symmetrical AWD. Thanks to the fact that the torque is distributed to all four wheels, the car demonstrates stable behavior both in the turning arc on an asphalt surface and when driving on a road with an uneven surface. The advantage of an all-wheel drive vehicle is especially noticeable when driving along winter roads. Secondly, four wheel drive vehicle more prone to neutral steering than its mono-wheel drive counterparts. Thus, its driver is much less likely to miss the turn. And, of course, an all-wheel drive car, as a rule, has good acceleration dynamics: the torque transmitted to all four wheels makes it possible to better realize the capabilities of high-power engines.
I wanted to add useful information about symmetrical drive Subaru and specifically my Legacy. Maybe for someone who still doubts whether to take this car or not, this information will be useful and important for making the right decision.
In those. In the characteristics, I indicated that the drive is permanent all-wheel drive and this is true, but it is also symmetrical. What does it mean?
The entire system is perfectly symmetrical relative to the longitudinal axis of the car. The load is evenly distributed on all four wheels providing exceptional stability while driving and maneuvering.
Any road, especially in Russia, has an uneven surface. Potholes, slippery areas, and even just puddles found on the asphalt when driving on high speed may cause loss of vehicle control. AWD all-wheel drive allows you to avoid loss of control by controlling the traction of each wheel at every moment. When one of the wheels slips, the car reacts to prevent skidding. Directional stability increases when driving at high speeds; the car does not “yaw” on uneven surfaces or rutted roads.
In difficult weather conditions The grip of the tires on the road is noticeably deteriorated. Slippery road covered with freshly fallen snow, this is an almost insurmountable obstacle for a car with two-wheel drive. If any of them gets stuck, the driver is practically doomed to seek outside help. All-wheel drive system AWD, installed in Subaru cars, gives even exclusively city cars the power and cross-country ability of SUVs. If any of the wheels loses traction, the load is redistributed to the others and the car continues to move.
On a high-speed highway, negotiating even turns that are not very sharp at first glance, a car with two-wheel drive can unexpectedly slip into a skid. This occurs due to a gradually and imperceptibly increasing centrifugal force, affecting him during the maneuver. The excellent balance of all the designs of the Subaru all-wheel drive system and the force that is transmitted to each wheel allow you to perfectly follow the chosen trajectory. For the first time, a city car gains dynamics and handling racing car. It was after Subaru that many other auto manufacturers began to equip their cars with all-wheel drive systems, but this company remains a leader in the quality of its developments.
The system combines a fairly low center of gravity, which is inherent in Subaru boxer cars, and complete lateral symmetry of the transmission. This solution combines excellent vehicle weight distribution and perfect balancing, thanks to which AWD (All Wheel Drive) provides excellent stability and excellent wheel grip. road surface in absolutely any conditions. A big plus This system is to place all components on one line: engine, transmission, rear differential and cardan, forming a symmetrical structure in the horizontal plane. This solution is very important for the ideal distribution of the vehicle's weight along the length and width, which gives a neutral balance that ensures a more comfortable and safe driving experience.
To confirm all this, I suggest watching the video at the link below. The topic of ice in Russia is more relevant than ever. Personally, when buying a car, I made a big bet on safety, because... the life of my family is important. And since we have winter for six months at a time, the choice was obvious in favor of all-wheel drive. Only on Subaris it really is the best. WHAT CAR DO YOU THINK CLIMBED THIS HILL? The question will be answered at the end of the video!
https://rutube.ru/tracks/3786687.html?v=aaf61c7931770df4820410f172d4b397.
