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The regeneration characteristics of a membrane containing ceramic foam diesel particulate filter are discussed. Two regeneration methods were employed to evaluate four different trap systems. A manually operated burner system was used to determine thermal durability while an exhaust throttling system was used to evaluate a complete system. With the exhaust throttling system, two non-catalyzed traps, a non-catalyzed trap with the engine operating on a copper fuel additive, and a base metal catalyzed trap were evaluated. The goal of the catalyst system evaluated was the simultaneous reduction of both particulates and NOx emissions. Diesel particulate emissions were monitored and collected for this study in a test cell at the Southwest Research Institute using repetitive EPA heavy duty transient cycles. A 1989 Caterpillar 3406B PEEC engine was used in the majority of the tests conducted.

To obtain low friction engine through piston ring design, a set of two piston rings (two-ring set), one compression ring and one oil ring, has been recently developed. To reduce the number of compression rings from two to one, double angle step joint was employed for the shape of top ring gap, and taper face was introduced to O.D. surface shape. Major subjects of two-ring set were to reduce the oil consumption, to increase the durability, and to get the reliability of double angle step joint. The authors obtained the two piston ring design and the reliability of double angle step joint by rig tests and engine tests.

New types of potentiometric NOx sensors suitable for use on automobiles were developed by using stabilized zirconia as a base solid electrolyte. It was found that the sensor with sensing electrodes of metal oxides (CdMn2O4 or NiCr2O4) showed excellent response to NOx in the concentrations between 20 and 4000 ppm at temperatures higher than 600 °C. The electromotive force of the sensors was almost linear to the logarithm of the NOx concentrations with positive slope for NO2 and negative slope for NO. Especially, the sensor fitted with CdMn2Os gave excellent responses to NO at 600 °C, while the sensor fitted with NiCr2O4 showed high sensitive to NO2 at 650 °C. The sensors were insensitive to CO, CO2, CH4, C3H6, O2 and water vapor. The sensors were fabricated as planar types with the reference electrode exposed to the sample gas, so that the sensors were simple in structure and easy to manufacture.

To reduce the oil consumption in diesel engines, the combination of top ring gap clearance (C1) and second ring gap clearance (C2) (ring gap balance) was applied. The effect of the ring gap balance on piston ring axial motion and second land pressure was observed and factors to control oil consumption were analyzed. The authors obtained a technique to reduce oil consumption by decreasing second land pressure and thus making second ring liable to lift off. Blow up gas was significantly concerned about oil consumption of blow-by gas.

Today preservation of the global environment is an international challenge, and air pollution has attracted more concern than ever. Especially, pollution due to exhaust emission from automobiles is a serious matter, and among others, the improvement of exhaust emission is urgent. For this purpose, regulations have been tightened on exhaust emission such as particulate control and NOx control. Thus, it is essential for oil consumption of diesel engines to reduce oil consumption and employ Exhaust Gas Recirculation (EGR), and piston rings are the important key to solve these problems. This paper clarifies the effect of top rings, among piston rings, on oil consumption through engine tests and theoretical calculation of oil film thickness, and suggests techniques to reduce oil consumption.

Catalytic reduction of NOx from diesel engine exhaust by the addition of saturated hydrocarbons, or diesel fuel has been demonstrated using a newly developed copper containing catalyst system. Fundamental interactions between NOx, oxygen and hydrocarbons over the copper based catalysts have been studied in relation to NOx reduction by hydrocarbon additions and in relation to hydrocarbon oxidation. The different NOx reduction characteristics of the various hydrocarbons, were revealed. Based on this work, the catalyst system and the hydrocarbon spray system have been designed to effectively reduce NOx over a wide exhaust temperature range. In laboratory experiments, the newly developed catalyst system combined with a diesel fuel or heavy saturated hydrocarbon spray system effectively reduces NOx by 20%-30% over an exhaust temperature range of 350°C - 550°C.

Using a supplemental fuel spray system, the catalytic reduction of NOx from the exhaust of a diesel engine has been demonstrated. The mechanism for NOx reduction will be discussed by reviewing the preliminary work conducted to evaluate the fundamental interaction between NO, oxygen and hydrocarbons using a fixed-bed flow system and IR spectroscopy. Based on this preliminary work, the incorporation of a copper containing catalyst system coupled with a diesel fuel spray system, has been shown to reduce NOx by 30% at exhaust temperatures around 450°C. Using this technology, a total system for the “simultaneous” reduction of both particulates and NOx, based on engine operating conditions, is proposed.