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TRW Automotive to Supply Daimler with Enhanced Motor Pump Unit for Electrically Powered Hydraulic Steering

TRW Automotive Holdings Corp. will supply Daimler AG with a newly enhanced Motor Pump Unit as part of the Electrically Powered Hydraulic Steering system (EPHS) on selected new Mercedes-Benz models. The MPU delivers enhanced performance and environmental attributes when compared with conventional hydraulic solutions.

TRW’s motor pump unit. Click to enlarge.

With TRW’s motor pump unit, hydraulic assist is determined by the pump speed and controlled by a patented, brushless motor which provides assist only when it is needed. The system used on the various Mercedes models uses TRW’s newest high power motor pump assembly providing a hydraulic output power of up to 1,000 watts. Compared with traditional hydraulic power steering, the system also offers fuel savings of up to 0.29 L/100km and a reduction of carbon dioxide emissions of approximately 6 g/km.

TRW’s motor pump unit provides flexible tuning capability allowing the 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.


Henry Gibson

This is part of the the beginning of the no belt ICE automobiles and their greater efficiencies. Fans were first. The alternator should be part of the flywheel. ..HG..


Is there some reason they put hydraulics in the middle?


All ancillary units should be standardized and electrified ASAP.

ICE + HEV + PHEV + BEV could share the same mass produced electric ancillary units for greater efficiency at much lower cost.

Many e-ancillary units manufacturers in China, India and other lower labour cost countries will have a field day.

Lower cost will benefit e-vehicles buyers.


Anyone know if there's any life in the 42 Volt "Standard"?
Seems this would be ideal for running various ancillary units.



In HEV/PHEV/BEV configurations, all the energy required for the e-ancillary units could come from the main battery pack, via a small converter, to avoid a second battery system. The voltage may very well be 42 volts or any other adequate voltage required by the standardized e-ancillary units.

Alternatively, a stand alone 42-volt system for e-ancillary units may offer added safety, if it can be recharged effectively by, (roof top PVs, on-board mini wind turbine, earth magnetic field, breaking energy? etc)

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