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Technical Paper

Advanced Planar Oxygen Sensors for Future Emission Control Strategies

This paper presents advanced planar ZrO2 oxygen sensors being developed at Robert Bosch using a modified tetragonal partially stabilized zirconia (TZP) with high ionic conductivity, high phase stability and high thermo-mechanical strength. Green tape technology combined with highly automated thickfilm techniques allows robust and cost effective manufacturing of those novel sensing elements. Standardization of assembling parts reduces the complexity of the assembly line even in the case of different sensing principles. The sensor family meets the new requirements of modern ULEV strategies like fast light off below 10 s and linear control capability as well as high quality assurance standards. High volume production will start in 1997 for European customers.
Technical Paper

A Study of Intake Air Pressure Sampling Position in a Throttle Body Module

In electric fuel injection (EFI) systems the intake air pressure is used as system load signal for calculating injection and ignition parameters together with engine speed. Part of an EFI system for motorcycles is a throttle body module with integrated pressure sensor. As motorcycle systems require smaller components than automotive applications the target for engineering is to minimize the component size and still fulfill other system requirements. Therefore the pressure sensor sampling point should be as close as possible to the throttle shaft to reduce the module size but with a sufficient distance to avoid signal distortion by unsteady flow. This paper describes how to find a suitable sampling position by combining static bench testing, dynamic vehicle testing and CFD analysis.
Technical Paper

A Study of Heated vs. Unheated Oxygen Sensor Applied on a Motorcycle EFI System

In the future more stringent emission regulations will enforce closed loop control of engine management systems for a large number of inexpensive low displacement motorcycles in markets like China and other Asian countries. Specific low cost Electronic Fuel Injection (EFI) systems have been developed or are under development to meet these requirements. This study presents a comparison of heated vs. unheated oxygen sensors in such a system. The exhaust gas temperature rise and variation during the emission test cycle in this class of motorcycles and its impact on the light-off time, the dynamic response behavior as well as other small engine specific parameters are investigated. Most experiments have been carried out on a 125cc motorcycle equipped with water cooled 4 stroke engine with 3 way catalyst.