refers to a form of four-wheel drive vehicle has been maintained throughout the process of moving the form of four-wheel drive, a fixed engine output torque distribution ratio to front and rear wheel, this drive mode can always have a good off-road performance and handling, but it can not be made to adjust the torque distribution according to road conditions, and the higher fuel consumption.
1. The four-wheel drive in the form of noun
in the form of four-wheel drive vehicle refers to the entire process of moving the form of four-wheel drive has been maintained, the engine output torque at a fixed ratio to the front and rear distribution wheel, this drive mode can always have better off-road performance and handling, but not able to make adjustments torque distribution according to road conditions and high fuel consumption.
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2-wheel-drive form classification
The most common form of four-wheel drive can be divided into three categories: four-wheel drive, four-wheel drive timely, full-time four-wheel drive.
3. The four-wheel drive substantially description
good reliability, but not for a long time on a paved road. Time-history of the oldest four-wheel drive. The so-called four-wheel drive can be simply understood that the driver can manually switch the four-wheel drive or two-wheel drive mode depending on road conditions, some lever of the transfer case, and some electronic buttons or knobs. Features of this system is the four-wheel drive, the driver needs to switch between two drive and four-wheel drive by the manual operation splitter, and four-wheel drive is not used for a long time in a paved road.
FIG simplified structure with sheets to illustrate the principle of four-wheel drive.
● sharing principle
can be seen, the power output of the engine can be transmitted to the front and rear axles via a power splitter in order to achieve four-wheel drive. Four-wheel drive system using SUV models, in general, 2H, 4H, 4L these stalls, mainly achieved by two drive splitter, the high-speed switching between four-wheel drive, low-speed four-wheel drive.
Since splitter four-wheel drive system where there is no center differential, andUpon turning on the four-wheel drive, front and rear axle is rigidly connected, for a fixed power distribution ratio. As paved road when turning due to the large front wheel turning radius than the rear wheels on the same side, so the front wheel speed is faster than necessary, so that the rotational speed around the axis is not the same, there will be “cornering brake “The phenomenon. This situation splitter, differential, drive shaft, tires and other components are damaged, so that four-wheel drive mode is only suitable for off-road use or in some snow, slippery road, paved road with two exchange should drive mode.
● timeshare
This four-wheel drive system is simple, with high stability, to emphasize the common four-wheel off-road hardcore, such as Pajero, Jim , Cherokee and so on. Some hardcore SUV models also use this system, such as the Great Wall Haval H5, Landwind X8, Roewe W5 and so on. .
● sharing models
4-wheel drive substantially timely description
timely four-wheel drive features: simple and cheap but the weakest performance
is a so-called four-wheel drive vehicle according to timely traveling road, the system automatically switched depending on the driving situation to two or four-wheel drive mode, the process does not require human operation. This four-wheel drive system with respect to the four-wheel drive system, eliminating the tedious manual operation, nothing to worry about because the switching system damage resulting from improper four-wheel drive, four-wheel drive system and even a lot of time to cut too notice it.
● timely principle
Koleos timelyFour-wheel drive system, uses a multi-plate clutch type limited slip differential. Multi-plate clutch differentials differential torque produced mainly by a wet clutch plate, while pressing the separation clutch is controlled by an electronic system. During normal driving of the vehicle, the drive in the form of a precursor, such as when the system detects wheel slip, the clutch is pressed by the electronic control system, in turn part of the power to the rear wheel, and in theory, the computer based on the vehicle speed in road 100: 0 torque between the front and rear axles are automatically assigned 50:50 to achieve grip performance optimization. After
However, this four-wheel drive system is usually the main driving wheels lose traction (slip), the other wheel will be passive intervention, so it’s slow to respond. Relatively speaking, timely four-wheel active safety as good as full-time drive the vehicle height. Further, front and rear axles timely four-wheel drive system basically an open differential, as in some complex sections, when one-side two wheel slip, is not turning around. Therefore, this four-wheel drive system that running a general bad roads okay, once the strength of the large number of off-road sections encountered on the powerless.
● timely four-wheel drive operation
Equipment timely four-wheel drive car is easy to use, it is widely used in urban SUV or cars such as the Honda CR-V, modern IX35, Toyota RAV4, X-Trail, koleos and so on. .
5 AWD substantially description
AWD characteristics: good performance generally complex and expensive wire catch Cock
AW often see at the end of some SUV modelsD word, in fact, this is the abbreviation for full-time all-wheel drive system (All Wheel Drive) is. The so-called full-time four-wheel drive means is always four wheel vehicle drive force can be provided separately, kept during running-wheel drive in the form of engine output torque at a constant rate assigned to the front and rear wheel, having good off-road and handling.
The center differential ●
AWD automobile transmission, a center differential is provided, the power distribution to the front and rear drive axles. And four-wheel drive, four-wheel drive is different is timely, full-time four-wheel drive vehicle traveling in four-wheel drive remains will be depending on the road conditions, the center differential engine power to allocate a certain percentage to the front and rear wheels.
because it is “always” four-wheel drive, four-wheel drive system with respect to the other two is not the time to switch between drive and four-wheel drive in response, superior active safety. Principle will also be appreciated from the structure, with respect to the two drive type, four-wheel drive is the drive train through the power output of the engine distributed to the four wheels, it is possible to obtain more stable traction. Even when the limit is hit the road (muddy wetlands, mountain) or intense driving, full-time four-wheel drive has a high pass and stability. However, with respect to timely four-wheel drive, a higher fuel consumption.
AWD system is used for the high-end models, such as Benz 4MATTC, BMW xDrive, Audi quarrtro, SH-AWD Acura and the like.
● a full-time four-wheel type
Summary: time-wheel drive configuration is simple, high reliability, but the need to manually switch the four-wheel drive, the current multi-biased hardcore off-road vehicle use. Timely and convenient four-wheel drive vehicles, widely used in urban SUV models, but four-wheel drive performance is the weakest. AWD and more used in high-end SUV models, with excellent road performance, but complex and expensive structure, high reliability and no four-wheel drive.