Sonchal, C., gajankush, J., Kulkarni, A., and pawar, S., "Energy Efficient Hydraulic Power Assisted Steering System (E2HPAS)," SAE Technical Paper 2012-01-0976, 2012, doi:10.4271/2012-01-0976.
A hydraulic-assisted power steering system on a vehicle has a steering pump which is directly driven from the engine continuously. In real world, the assistance from the steering pump is useful only while maneuvering. During a typical highway drive, assistance from this power steering pump remains unused for majority (76%) of the time; although the continuously rotating power steering pump keeps consuming energy from the engine. An electronic controller has been provided for the electro-magnetic pairing device of the power steering pump in order to provide assistance for steering based on driver demand only. The electromagnetic pairing device integrated on the steering pump can be made to engage/disengage based on the driver demand through the electronic controller. The benefit with such a system includes reduced energy consumption from the engine (lower CO₂ emission) & consequent improvement in fuel economy (4 to 6% improvement in highway fuel efficiency) coupled with on-demand power assistance to steering.