Improved Fuel Consumption through Steering Assist with Power on Demand 2008-21-0046
The paper compares hydraulic, electro-hydraulic, and electric power steering in terms of power consumption and possible innovative features:
Conventional hydraulic assisted power steering:
Good steering performance. High energy consumption because hydraulic pump is constantly driven by combustion engine. Innovative steering functions are not possible with this technology.
Electro-hydraulic power steering:
Good steering performance. Reduced energy consumption because hydraulic pump is driven by continuously operating electric motor. Rpm of motor is depending on requested steering assist: partial power on demand. Innovative steering functions are not possible with this technology.
Electric power steering:
Minimal energy consumption due to power on demand: electric motor runs only when steering assist is required by driver. Enabling technology for advanced vehicle control functions.
Besides the obvious advantages in power consumption this paper will also address the challenges regarding system performance which need to be considered before bringing the EPAS on the road, such as steering feel, safety according to SIL3, power density, requirement for new features, and last not least cost.