TRW Automotive to supply electrically powered hydraulic steering for a range of light commercial vans
|TRW’s EPHS system features its own motor pump unit that supplies power on demand to enable steering assist independent of the engine, saving fuel and reducing emissions. Click to enlarge.|
TRW Automotive Holdings Corp. says it has landed a major contract win to supply a range of vehicle manufacturers with Electrically Powered Hydraulic Steering (EPHS)—a system that allows a conventional hydraulic steering system to run without an engine-driven hydraulic pump (earlier post)—for light commercial vehicle (LCV) van platforms that will launch in 2013.
EPHS is a hydraulic steering system powered by an electric Motor Pump Unit (MPU) independent of the engine; the system comprises a conventional rack and pinion power gear and a compact MPU. The MPU combines an electronically commutated brushless motor, a gear pump with a resonator, a tank for the hydraulic fluid and an electronic control unit (ECU) with the control electronics and power electronics in one housing.
TRW’s EPHS offers comparable fuel economy and CO2 reduction benefits to full electric steering, but EPHS also accommodates higher rack load applications, the company says. Its latest generation EPHS system, Gen-C, is a market leader in terms of output power derived from 12 volt systems.
This mature technology supports light commercial or panel vans, as they're called. These panel vans often drive more than 100,000 km per year per vehicle. With fuel efficiency of up to 0.3lg per 100km and related CO2 reduction of approximately 7g/km, fleet operators and individual businesses can really quantify the benefit. With more than 20 million systems in the field, EPHS is a proven solution and fleet operators can be confident of its reliability and performance.—Charlie Cregeur, global steering product planning director for TRW
TRW’s EPHS system also benefits from its advanced speed proportional steering technology. This flexible tuning capability allows TRW’s EPHS system to adapt to different driving conditions, providing a comfortable setting for parking and city driving, while delivering a safe and robust feel at higher speeds. There is also the option for EPHS to vary assist levels depending on the vehicle loading information provided by other vehicle subsystems.
Looking at LCVs we see tremendous growth potential whenever tighter CO2 regulations are introduced and full electric steering cannot support the rack loads. Our Gen-C motor pump unit delivers up to 1kW power and supports rack loads of up to 18 kN for vehicles of up to 7 tons in weight.—Frank Lubischer, vice president, steering engineering