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Technical Paper

A Layer Structured Model Based Diagnosis: Application to a Gear Box System

OBD (On Board Diagnosis) has been applied to detect malfunctions in powertrains. OBD requirements have been extended to detect various failures for ensuring the vehicle emission control system being normal. That causes further costs for additional sensors and software works. Two layers diagnosis system is proposed for a passenger car gearbox system to detect changes from normal behavior. Conventional physical constraints based diagnosis is placed on the base layer. Model based diagnosis and specific symptom finding diagnosis are built on the second layer. Conventional physical constraints based diagnosis is direct and effective way to detect the failure of system if the detected signals exceed their normal ranges. However under the case of system failure with related signals still remain in normal ranges, the conventional detection measures can not work normally. Under this case, Model based diagnosis is proposed to enhance the functionality of diagnosis system.
Technical Paper

NOx Trap Catalyst Technologies to Attain 99.5% NOx Reduction Efficiency for Lean Burn Gasoline Engine Application

For fuel economy improvement by lean-burn gasoline engines, extension of their lean operation range to higher loads is desirable as more fuel is consumed during acceleration. Urgently needed therefore is development of emission control systems having as high NOx conversion efficiency as three-way catalysts (TWC) even with more frequent lean operation. The authors conducted a study using catalysts loaded with potassium (K) as the only NOx trapping agent in an emission control system of a lean-burn gasoline engine.
Technical Paper

New DOC for Light Duty Diesel DPF System

A new state of the art DOC (Diesel Oxidation Catalyst) having superior light-off and exothermic activity for forced regeneration compared to conventional Pt base passive DOC, was investigated for LDD application. The DOC uses the latest Pt/Pd technology resulting cost effective DPF system. The newly developed DOC demonstrated improved catalytic activities from Pt only DOC in model gas or engine bench tests. In this study, DOC at early development stage showed excellent light-off activity in model gas and engine bench test compared to conventional Pt only DOC, however, it showed “extinction” phenomenon which is one of the deactivation mode while the post injection and it was observed when post injection operation was done at lower DOC inlet temperatures, e.g. below 250 C. Temperature profiles along diameter and length into DOC bed while active regeneration suggested extinction would be caused by fouling of supplied hydrocarbons derived from diesel fuel.
Technical Paper

Analysis and Design Requirements for Tandem TWC Systems

Two-brick (tandem) three-way underfloor catalyst systems provide greater emission reduction performance compared to comparable single brick TWC systems, which contain the same amount of platinum group metal (PGM) for the same catalyst volume. This superior emission reduction performance is speculated to be due to front catalyst activity promoted by heat transfer from reverse exhaust gas flow in the gap between the front and the rear catalyst of tandem TWC system (hereinafter, tandem gap). Furthermore, the following findings were obtained by conducting experiments with model catalysts. 1) During catalyst light-off phase, conversion efficiency strongly depends on activity of the front portion of catalyst where temperature rises rapidly.
Technical Paper

NOx-Trap Catalyst Development for Mitsubishi 1.8L GDI™ Application

A new single-brick Ba + alkali metals NOx-Trap catalyst has been developed to replace a two-brick NOx-Trap system containing a downstream three-way catalyst. Major development efforts include: 1) platinum group metals selection for higher HC oxidation with potassium-containing washcoat, 2) alumina and ceria selection, and Rh architecture design for more efficient NOx reduction and 3) NiO to suppress H2S odor. Mitsubishi Motors' 1.8L GDI™ with this Delphi new NOx-Trap catalyst with H2S control achieves J-LEV standard with less cost and lower backpressure compared to the previous model. It is further discovered that incorporation of NiO into the NOx-Trap washcoat is effective for H2S control during sulfur purge but has a negative impact on thermal durability and sulfur resistance. Further study to improve this trade-off has been made and preliminary results of an advanced washcoat design are presented in this paper. Details will be reported in a future publication.
Technical Paper

Optimization of Heavy Duty Diesel Engine Parameters for Low Exhaust Emissions Using The Design of Experiments

For compliance with stringent exhaust emissions regulation, a lot of the world's Heavy Duty Diesel Engines (HDDE) have been recently equipped with electronically controlled components, such as the Fuel Injection Equipment (FIE), Exhaust Gas Recirculation (EGR) system, Variable Geometry Turbocharger (VG). Flexibility of engine control has been increasing more and more with electronic control for low exhaust emissions and good performance. However, determination of the optimum combination of engine control parameters is extremely tedious, because an engine has so many parameters to be optimized and their interactions are complicated. Therefore, a Design of Experiments (DOE) method was used to optimize the engine control parameters, which effect emissions and performance, in a shorter time. After using this method, it was recognized that it was an effective method to optimize various engine parameters, and was very convenient for engine development.
Technical Paper

Emission Reduction Technologies Applied to High-Speed Direct Injection Diesel Engine

In this paper, emissions reduction technologies applied to high-speed direct injection (HSDI) diesel passenger car engines to meet the stricter exhaust emission legislation are described. To reduce smoke, the F.I.E. has been improved by using a radial-piston distributor pump which delivers fuel-injection-pressure up to 120MPa. Cooled exhaust gas re-circulation (EGR) system and increase in volume ratio of the combustion chamber has made it possible to increase EGR ratio and reduced nitrogen oxides (NOx) and smoke simultaneously. Furthermore, improvements in the oxidation catalyst activating temperature reduces PM at lower exhaust gas temperatures. As a result of applying these technologies, a clean and economical HSDI diesel engine for passenger cars, which complies with Japanese '98 exhaust emissions legislation and has better fuel economy than indirect injection (IDI) diesel engines (above 15%), has been developed.
Technical Paper

Effect of Air-Fuel Ratio Modulation on Conversion Efficiency of Three-Way Catalysts

The widening of the selectivity windows of a three-way catalyst under A/F ratio modulation was shown to result from retention of adsorbed species on catalyst surfaces and their subsequent reaction with gas-phase reactants. A reaction model was developed based on adsorption properties of CO, HC and NOx and by computer simulation, the conversion efficiencies of CO, HC and NOx under A/F ratio modulation were calculated. The calculated and experimental results were in good agreement.
Technical Paper


This paper describes the results of studies on the behavior of air-fuel ratios under feedback control, the effect of air-fuel ratio modulation on three-way catalyst conversion efficiency and emission test results with and without feed back control. As a further measure for decreasing automobile exhaust emissions, the three-way catalyst activity for reduction of CO, HC and NOx emissions is most effectively utilized when the normal engine air-fuel ratio perturbations are controlled and limited. In order to attain such an objective, this report describes the governing characteristics of an air-fuel ratio control system using an EFl engine coupled to a ZrO2 type O2 sensor and feed back loop. The conversion efficiency characteristics of a conventional three-way catalyst, using systematically modulated air-fuel ratios, and the resultant reduction of exhaust emissions with these systematic fluctuations and limited perturbations are also defined.
Technical Paper

The Effects of Exhaust Gas Recirculation and Residual Gas on Engine Emissions and Fuel Economy

Three exhaust emissions, hydrocarbons, carbon monoxide and oxides of nitrogen, from the automotive spark-ignition engines are presently subject to regulatory control. Of these harmful pollutants, NOx emissions are the hardest to control under current status of emission control technology. Accordingly, exhaust gas recirculation (EGR) has been receiving continued efforts as one of promising NOx control. This paper reports the effects of EGR on the mechanism of NOx reduction and engine fuel economy, on the basis of research made in the following areas: (1). NOx formation in a combustion vessel. (2). Studies on EGR effects in a single-cylinder engine. (3). Effects of EGR on NOx and HC emissions and fuel economy.