New generation of automotive sensors to fulfil the requirements of fuel economy and emission control

Abstract

The new passenger car regulations for future emission levels and the increasing demands for fuel economy have led to strong efforts to develop new engine-management systems, exhaust-treatment technologies and new automotive sensors. In this paper a new generation of automotive sensors that help to fuffil the requirements for fuel economy and emission control is presented. The demands on these new sensors include the following improvements: (i) better resolution, higher accuracy and better long-term stability, especially under severe environmental conditions; (ii) good performance at high temperature (e.g., up to 150 °C for rotational speed sensors and 1100 °C for exhaust gas sensors); (iii) short response times for dynamic cylinder-selective measurements; (iv) more efficient compensation methods by measuring different physical parameters. This talk gives an overview on the physical principle, the design, the technology and the application of a new generation of automotive sensors. Representing a potential 'high-volume' sensor, we report on an active rotational speed sensor to measure the angular position of the crankshaft. This sensor is based on a newly developed differential Hall IC. The high angular resolution allows more accurate ignition timing as well as 'misfiring' detection to be achieved. For the precise control of combustion in future engine-management systems, an 'air flow sensor' for cylinder-specific carburation, a 'combustion pressure sensor' for thermodynamic calculation of the combustion and a 'fast exhaust gas sensor' for cylinderselective exhaust-gas analysis can be used. This report will focus on the development of a fast oxygen sensor to measure the oxygen partial pressure of the exhaust gas. As an example of a smart sensor, an 'alcohol fuel sensor' for alternative fuel concepts is introduced. This sensor is a key component of a flexible fuel system which can be run on arbitrary mixtures of gasoline and methanol. This sensor measures three physical parameters: the capacitance, the conductivity and the temperature, in order to determine the methanol/gasoline ratio in the fuel rail with high accuracy. © 1992.