The Volkswagen 4MOTION articles of the four-wheel drive technology

On a four-wheel drive technology, Xiao Bian was mentioned where the Audi TT and A3 is the mass of the four-wheel drive system, just a different name for it. Quatto and 4motion has a wide variety of online saying: some say its source the same clan, some say its unrelated ... what really Xiaobian after a lapse of a half months after the search parties information, decided to use their own language Road for everyone to understand.

Figure: The structure of the viscous coupling

Everything has a root cause in order to thoroughly understand the public's 4motion, you must first understand its history. In 1986, Volkswagen was the second-generation Golf is equipped with four-wheel drive system, and to make those the models named Xin Keluo (the Syncro), while the figure above the viscous coupling is four-wheel drive the core part of the system.

The figure is a viscous coupling power transmission line. This axle without speed difference, the silicone oil does not work, the front drive automobile showed characteristics, more than 95% of the torque output by the front wheels. Once the front axle slip, silicone oil temperature rose, the thermal expansion tends to zero, forcing the air within the volume occupied by the viscous coupling, dramatically increase the pressure within the casing, pushes the inner blades tightly pressed on the outer blades, the use of blade between the inside and outside metal friction, the viscous coupling at both ends directly fused viscous Coupling locked up a 50:50 torque distribution front and rear axles. This is a viscous coupling as inter-axial differential lock principle.

Viscous Coupling has a simple structure, low manufacturing costs, the torque transmission advantages of soft, but because of its slow response differential, Volkswagen introduced in 1998, the Swedish Haldex coupler replace Viscous Coupling as 4Motion core parts . As for small why it took great efforts to introduce seemingly has nothing to do with today's 4Motion viscous coupling, very simple, the the Haldex coupler transmission principle with viscous coupling is basically the same, except that: ① the degree of electronic by ECU control bonding time and bonding torque; ② a hydraulic mechanism driven annular piston blade engagement, The accumulator institutions so that the blade can be engaged in the fastest time, improve response speed slip. The left and right wheels slip, then rely on the the ECU calculation of the degree of slip and brake slipping wheels turning around.