This paper is concerned with power consumption analysis for conventional steering system, the importance of duty cycle before choose appropriate pump drive system, and the energy saving potential of the proposed systems. After reviewing the recent efforts in developing energy-efficient steering system, two new on-demand pump drive systems are proposed to provide varying flow according to vehicle engine speed. One is the combination of a sized pump without flow control valve and an Electrical Power Hydraulic Steering (EPHS) unit. The other is the combination of multiple EPHS units. The energy saving advantage of the combinations will be emphasized for different duty cycles. The inherent low efficiency of the conventional steering system was analyzed. Both the feature of coupled metering-in and metering-out lying in the steering gear and that of fixed displacement lying in the pump contribute to the energy wasting. Without modifying the coupled meter-in and meter-out, two new on-demand pump drive systems can still save energy considerably. Under some assumptions, the mechanical power consumptions from engine by different systems have been quantified. For low duty cycle application, neither the sized pump system nor multiple EPHS combination is a good choice. If the duty cycle is relatively high, the sized pump system has great margin of energy saving. If the duty cycle is high enough, multiple EPHS combination may be chosen. Additionally, power requirement shall be taken into account in choosing which one of them. In order to simplify the analysis, the power consumption for steering is ignored. This approximation is good enough for highway vehicles. The separating of idling engine and cruising engine may apply to highway vehicles pretty well because the intermediate status occupies little time. However, this separating may not apply to city suburban transit vehicle.
Energy saving analysis of power steering system by varying flow design
2007
6 Seiten, 7 Bilder, 9 Quellen
Conference paper
English
Energy Saving Analysis of Power Steering System by Varying Flow Design
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