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Development of an Electrical Power Steering (EPS) system for Emergent Markets, with emphasis on improved fuel economy and cost advantages to the customer. The EPS for Emergent Markets provides high steering wheel assistance on parking maneuvers and appropriate assistance on driving conditions similar to conventional EPS systems. The assistance levels decreases while vehicle speed increases providing better steering feel at high speed conditions (highway tracks). It also provides good tuning capability balanced with piece cost. In addition, this EPS enables an aftermarket bolt-on system for non-assisted steering vehicles (i.e., manual steering vehicles).

Due to lower tax rates there are in Brazil many vehicles equipped with 1.0L engines. Nevertheless, consumers still want in these cars air conditioning, steering assistance and embedded electronic devices. The low power developed by such engines can, in some cases, compromise the quality of the electrical power supply in the vehicle, leading to voltage fluctuations, which could interfere with the dynamic behavior of Electric Power Steering (EPS) systems. In the worst case, voltage dips could induce undesired torque pulses on the steering wheel, causing an unpleasant feeling for the driver. The present work demonstrates a power supply fluctuation compensation strategy that electronically minimizes the consequences of sudden voltage dips in vehicles equipped with 1.0L engines. Simulations and experimental results are also included.

This paper presents an objective evaluation using order analysis to quantify the noise levels generated by the pumps of the power steering system mounted on a test stand and operating under two pressure load conditions (5 and 50 bar) in the working range between 500 and 5.000 rpm. Also, under these conditions experimental tests are carried out to verify the influence of the output pulsating pressure of the pump on the noise and vibration measurements.

In this study the moan and whine noises of the pumps of the Hydraulic Power Steering systems are investigated experimentally through the measurements of the dynamic hydraulic pressure in the pump outlet installed in a test stand. The vibro-acoustic performance of the pumps is evaluated applying two objective metrics. One of them consisted of the pressure amplitude sum and the other identified the maximum amplitude, in the frequencies of interest (fundamental frequency and harmonics). The results of the dynamic pressure measurements of pumps installed in a test stand are compared with the subjective qualification of the same pumps installed in an actual vehicle by the grades given by trained listeners.

This work presents a numerical model to simulate oil flow in power steering pumps. A detailed three-dimensional geometry was used, considering rotor, inlets and outlets. Moving mesh capability was used because of the variations of the domain geometry with the pump rotation. Two operating conditions were simulated: 3000 rpm and 8000 rpm. The results investigated low pressure regions which could give place to cavitation problems and recirculation zones, as well as geometric details used to improve performance and reduce of pressure fluctuations and noise levels.

The application of sound quality tools in the design process of electro-hydraulic power steering (EHPS) is investigated in this paper. The EHPS acoustics performance is investigated by studying the correlation between objective measurements and subjective evaluation of the noise from the EHPS.