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TRW Automotive to supply electrically powered hydraulic steering for a range of light commercial vans

Trweps
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

Comments

HarveyD

This is another electro-hydraulic steering where the hydraulic belt driven pump has been replaced with an electric motor driven one.

Many pure electric power steering exist and have been used in many cars since 1990.

Why retain the hydraulic pump when pure electric units can do the same job?

Account Deleted

This systems doesn't only offers comparable fuel economy and CO2 reduction benefits to full electric steering, but also less maintenance for owner and also reduce any leaks possibility on hydraulic system. mobil bekas

Engineer-Poet
Why retain the hydraulic pump when pure electric units can do the same job?
FTA:
TRW’s EPHS offers comparable fuel economy and CO2 reduction benefits to full electric steering, but EPHS also accommodates higher rack load applications
RFTA next time.
HarveyD

Electric steering can easily be designed with various rack loads. One of the good side of electric steering is that it can be modulated for various speed and loads.

George Furey

Electric power steering poses several problems of its own. Even in small applications heat buildup is an issue due to the fact that the motor is sealed and not continuously spinning to allow a cooling fan. I would assume they are going with an electro-hydraulic system for larger applications to prevent motor burnout

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