Search Results

Cylinder air/fuel ratio distribution is an important factor affecting the economy, power, vibration, and emissions of an internal combustion engine. Currently, production automobiles utilize an exhaust gas sensor located in the main exhaust stream in order to regulate air/fuel mixtures. By measuring the oxygen content of the exhaust gas for each cylinder independently, the degree of air/fuel variation between cylinders can be determined. This information can be used to determine the mixture quality of specific cylinders. Knowing these variances can lead to design changes in the intake and exhaust manifolds as well as better control of fuel metering which will improve the output of the engine. This study was carried out using a 1991 3.8L Buick V-6 engine with customized exhaust manifolds utilizing exhaust gas oxygen sensors for each cylinder in addition to the sensor located in the main combined exhaust gas stream. Production level, ZrO2 sensors were used for this experimental study.

The placement and design of heat shields is a critical step in the design of todays vehicles. Computer modeling of heat shield configurations can help to optimize shielding performance while minimizing their size and cost. In this paper an attempt was made to determine the most effective shielding arrangement between the exhaust system and the fuel tank. It has been determined through numerical experimentation that vehicles equipped with plastic fuel tanks should have tank shields installed as a first preference over exhaust shielding in most practical applications.

Currently automobile companies are facing some major problems in the area of heat management. Many components experience excessive heat build-up which result in high waranty costs and bring up safety related concerns. Presently manufacturers shield high temperature exhaust components with thin metalic heat shields. A major concern is the close proximity of the exhaust system to a variety of critical components. Such components include gas lines, gas tanks, oil lines and the floor pan. Three forms of ceramic based insulation were applied to the vehicle exhaust system for testing and evaluation, namely a fibrous blanket, a brush-on coating, and a moldable putty. The exhaust system, as well as some critical components, were thermocoupled for the three different insulations as well as for a baseline test of an uninsulated but mechanically shielded exhaust.