5.1.1. Principle of action of EPS
The electrohydraulic steering with the amplifier reduces effort to the steering mechanism. The hydrosystem operates also as well as steering system with the amplifier, used on other models, however its structure includes the hydraulic pump with the electric drive, independent of the car engine. The control unit and the pump of hydrosystem make the uniform module and can be replaced only assembled.
The effort from EPS is regulated by the control unit, as function of frequency of rotation of the engine and according to the three-dimensional adjusting characteristic of the engine.
On the car two various systems EPS are used.
EPS of production TRW is used on versions with petrol engines of small capacity and Z 17 DTL and does not join in tire CAN system. For diagnostics, this system has own line of diagnostics (a conclusion of diagnostics 7). EPS of production TRW provides two-level, depending on loading, regulation of speed of rotation of the pump (2 speeds). The size of loading is determined by a current, which electric motor consumes from electric system of the car.
EPS of production ZF is used on petrol engines of big capacity and Z 17 DTH and is connected with the tire HS CAN. EPS of production ZF works depending on speed and loading and uses two various adjusting cards. The corresponding traffic conditions are determined by speed of the car as function of shift of a steering wheel, and servousily a steering decreases at increase in speed of movement. On cars with the sports chassis, the second adjusting card can be made active by the button of inclusion of a sports mode.