Abstract
Abstract
Nowadays, for cost and pollution reasons, the development of new vehicles is strongly driven by a research of fuel consumption reduction. One interesting way for such fuel economies is the replacement of actual hydraulic power steering by Electric Power Steering using high power Brushless DC motors. The typical fuel economy realized by shifting from a hydraulic to an Electric Power steering is about 5 percent. With the improvement of the Brushless DC motor structures and the increase of the electric power available with actual batteries, the market shares of Electric Power Steering should grow quickly in the next few years. In order to drive efficiently the BLDC motor, the ECU requires accurate information on the torque applied by the driver to the steering wheel. These torque information usually come from the shift measurement between two shafts linked by a linear torsion bar. The main concern in this measurement is due to the fact that these shafts are also rotating with the steering wheel and the integration of electronic on rotating parts is definitely a blocking point. MMT has developed an innovative low cost structure answering all the requirements of torque sensing for Electric Power Steering. This torque sensor is based on a contactless Hall effect principle and uses standard programmable Hall ASIC available on the market. This presentation will explain in detail the MMT patented torque sensor structure (designs, measurement results, …), and possible integration on the steering column.