Energy saving remains to the prime objective for every commercial vehicle makers. In this regard, Daimler has proposed an advanced and energy-efficient electrohydraulic power steering system (EHPS) for its buses with a gross weight of over 7.5 tonne. The new technology will replace the conventional Hydraulic power steering (HPS) systems used extensively in trucks and buses.
It is said that over 70% of the energy consumed by conventional HPS systems in CVs go waste and can be avoided. The EHPS systems, used widely in passenger cars, are effective and offer greater advantages – ECU programmed pressure-flow management, low fuel consumption, and an improved steering feel and response. But it poses serious challenges to its applications in heavy-duty vehicles. For instance, the electric power limitations of the 24-V electrical systems to handle heavier steering loads. Higher costs and reliability is an another issue.
In the Daimler’s EHPS system, the hydraulic steering-pump is no more powered by the engine, thus actuates on demand basis regardless of the engine speed. Packed in a single housing along with a 3-phase synchronous motor, ECU unit, and a high-performance electrical system, the 24 V pump provides required amount of steering assistance depending on the driving situation analysed by the ECU based on vehicle data. The system-based frictional loses within the hydraulic circuit is also greatly reduced, thanks to short hydraulic pipes and compact design.
The German CV major is planning to introduce the energy-saving EHPS system in the upcoming Mercedes-Citaro range of city buses as an optional equipment starting from mid next year. Increased application of the technology in heavy-duty commercial vehicles will bring down costs in future.Also Read: Mercedes-Benz Future Bus With CityPilot: Ingenious Self-Driving City Bus