Abstract
AWD drivetrain operation still suffers from the problem concerning functionality of the tire traction. Tire spin and/or slip due to continuously changeable operating conditions causes the directional instability of the vehicle and decreases the efficiency of the engine and braking system. Several improvements that incorporate electronic subsystems (e.g. ABS, ASR, and EDP) were made lately. However the essential property of such systems is their discrete mode of the operation, which can be rather annoying to the inexperienced driver. The driver has to be prepared to the new and extraordinary behavior of the vehicle that in our opinion represents the need for the additional training of the driver. Moreover the systems do not operate well in some operating conditions (e.g. snow on the road).
Therefore the new drivetrain concept that would operate uniformly through various changeable operating conditions was proposed. It would be composed of classic drivetrain elements, viscous devices and power branching devices. The essential part of the new drivetrain is the viscous device, which assures nonlinear but uniform transfer characteristic that is needed for the drivetrain to adapt to the varying traction conditions uniformly.
Characteristics of the main elements of the adapted drivetrain were measured and the drivetrain model was built. Several simulations of the drivetrain operation confirm the concept of the new drivetrain.
The modeling was done with the use of bond graphs. The technique was chosen due to its generality. To support the modeling the application with originally developed algorithms was designed and implemented into the software application. Simulation of various driving conditions was done.