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Technical Paper

Analysis and Prediction of Unburned HCs in a Lean-Burn Engine

2007-04-16
2007-01-0477
Three-dimensional combustion simulation tools together with the Universal Coherent Flamelet Model (UCFM), a flame propagation model, have been applied to SI lean-burn combustion to study the influence of the equivalence ratio on the amount of unburned hydrocarbons (HCs). Unburned HCs from piston-cylinder crevices were taken into the consideration by using a calculation grid incorporating the actual crevice volume and shape and by applying an autoignition model to post-flame phenomena. The calculation results show the general tendencies for the total amount of unburned HCs and their distribution in the combustion chamber.
Technical Paper

Summary report of Japan Clean Air Program diesel and diesel fuel activities

2007-07-23
2007-01-1952
Diesel emissions are significant issue worldwide, and emissions requirements have become so tough that. the application of after-treatment systems is now indispensable in many countries To meet even more stringent future emissions requirements, it has become apparent that the improvement of market fuel quality is essential as well as the development in engine and exhaust after-treatment technology. Japan Clean Air Program II (JCAP II) is being conducted to assess the direction of future technologies through the evaluation of current automobile and fuel technologies and consequently to realize near zero emissions and carbon dioxide (CO2) emission reduction. In this program, effects of fuel properties on the performance of diesel engines and a vehicle equipped with two types of diesel NOx emission after-treatment devices, a Urea-SCR system and a NOx storage reduction (NSR) catalyst system, were examined.
Technical Paper

Development of Thinnest Wall Catalyst Substrate

2002-03-04
2002-01-0358
The thinnest wall thickness of automotive catalyst substrates has previously been 30 μm for metal substrates and 50 μm for ceramic substrates. This paper describes a newly developed catalyst substrate that is the world's first to achieve 20-μm-thick cell walls. This catalyst substrate features low thermal capacity and low pressure loss. Generally, a thinner cell wall decreases substrate strength and heat shock resistance. However, the development of a “diffused junction method”, replacing the previous “wax bonding method”, and a small waved foil has overcome these problems. This diffused junction method made it possible to strengthen the contact points between the inner waved foil and the rolled foil compared with previous substrates. It was also found that heat shock resistance at high temperature can be much improved by applying a slight wave to the foil instead of using a plane foil.
Technical Paper

Development of Diesel Engine System with DPF for the European Market

2007-04-16
2007-01-1061
Nissan Motor has put on the European SUV market a 2.2-L direct-injection diesel engine with a diesel particulate filter (DPF) system that complies with the EURO IV emission regulations. This paper describes the DPF system, cooperative control of a variable geometry turbo (VGT) and exhaust gas recirculation (EGR), and a high-accuracy lambda control adopted for this engine. In order to achieve a compact DPF, the high-accuracy lambda control was developed to reduce variation in engine-out particulate matter (PM) emissions. Moreover, the accuracy of the technique for predicting the quantity of PM accumulation was improved for reliable detection of the DPF regeneration. Prediction error for PM accumulation increases during transient operation. Control logic was adopted to correct the PM prediction according to lambda fluctuation detected by an observer for lambda at cylinder under transient operating conditions. The observer is corrected lambda sensor output.
Technical Paper

Expansion of Premixed Compression Ignition Combustion Region by Supercharging Operation and Lower Compression Ratio Piston

2007-08-05
2007-01-3614
Various premixed diesel combustion concepts are suggested as the way of simultaneous reduction of NOx and PM emission from diesel engines. However, every combustion concept has common problems, such as difficulty of ignition timing control, a great deal of HC and CO emissions and limiting the operation region to low load operation. The purpose of this study is to expand the operation region of Premixed Compression Ignition (PCI) combustion, which is a premixed diesel combustion concept that realizes the fuel injection around the top dead center. As a result of examining it with EGR, supercharging operation and low compression ratio piston, PCI combustion region was expanded to cover higher load operation. And the high load region was limited by not only stoichiometric air fuel ratio but also permissible maximum in-cylinder pressure.
Technical Paper

Nano Particle Emission Evaluation of State of the Art Diesel Aftertreatment Technologies (DPF, urea-SCR and DOC), Gasoline Combustion Systems (Lean Burn / Stoichiometric DISI and MPI) and Fuel Qualities Effects (EtOH, ETBE, FAME, Aromatics and Distillation)

2007-10-29
2007-01-4083
Newly designed laboratory measurement system, which reproduces particle number size distributions of both nuclei and accumulation mode particles in exhaust emissions, was developed. It enables continuous measurement of nano particle emissions in the size range between 5 and 1000 nm. Evaluations of particle number size distributions were conducted for diesel vehicles with a variety of emission aftertreatment devices and for gasoline vehicles with different combustion systems. For diesel vehicles, Diesel Oxidation Catalyst (DOC), urea-Selective Catalytic Reduction (urea-SCR) system and catalyzed Diesel Particulate Filter (DPF) were evaluated. For gasoline vehicles, Lean-burn Direct Injection Spark Ignition (DISI), Stoichiometric DISI and Multi Point Injection (MPI) were evaluated. Japanese latest transient test cycles were used for the evaluation: JE05 mode driving cycle for heavy duty vehicles and JC08 mode driving cycle for light duty vehicles.
Technical Paper

Unregulated Emissions Evaluation of Gasoline Combustion Systems (Lean Burn / Stoichiometric DISI and MPI), State of the Art Diesel Aftertreatment Technologies (DPF, urea-SCR and DOC), and Fuel Qualities Effects (EtOH, ETBE, Aromatics and FAME)

2007-10-29
2007-01-4082
In order to clarify future automobile technologies and fuel qualities to improve air quality, second phase of Japan Clean Air Program (JCAPII) had been conducted from 2002 to 2007. Predicting improvement in air quality that might be attained by introducing new emission control technologies and determining fuel qualities required for the technologies is one of the main issues of this program. Unregulated material WG of JCAPII had studied unregulated emissions from gasoline and diesel engines. Eight gaseous hydrocarbons (HC), four Aldehydes and three polycyclic aromatic hydrocarbons (PAHs) were evaluated as unregulated emissions. Specifically, emissions of the following components were measured: 1,3-Butadiene, Benzene, Toluene, Xylene, Ethylbenzene, 1,3,5-Trimethyl-benzene, n-Hexane, Styrene as gaseous HCs, Formaldehyde, Acetaldehyde, Acrolein, Benzaldehyde as Aldehydes, and Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene as PAHs.
Technical Paper

The Effect of a Longer Stroke on Improving Fuel Economy of a Multiple-Link VCR Engine

2007-10-29
2007-01-4004
Some automakers have been studying variable compression ratio (VCR) technology as one possible way of improving fuel economy. In previous studies, we have developed a VCR mechanism of a unique multiple-link configuration that achieves a piston stroke characterized by semi-sinusoidal oscillation and lower piston acceleration at top dead center than on conventional mechanisms. By controlling compression ratio with this multiple-link VCR mechanism so that it optimally matches any operating condition, the mechanism has demonstrated that both lower fuel consumption and higher output power are simultaneously possible. However, it has also been observed that fuel consumption does not reduce further once the compression ratio reached a certain level. This study focused on the fact that the piston-stroke characteristic obtained with the multiple-link mechanism is suitable to a longer stroke.
Technical Paper

Parametric Study and Clarification of Determination Factors of Diesel Exhaust Emission Using a Single Cylinder Engine and Model Fuels - JCAP Combustion Analysis Working Group Report Part I

2002-10-21
2002-01-2824
Single cylinder engine testing was carried out to clearly understand the test results of multi-cylinder engines reported by the Diesel WG in JCAP (Japan Clean Air Program) (1), (2), (3) and (4). In this tests, engine specifications such as fuel injection pressure, nozzle hole diameter, turbo-charging pressure, EGR rate, and fuel properties such as 1-, 2-, 3-ring aromatics content, n-,i-paraffins content, and T90 were parametrically changed and their influence on the emissions were studied. PM emission generally increased in each engine condition with increased aromatic contents and T90. In particular, multi ring aromatics brought about large increases in PM regardless of the engine conditions. The influence of fuel properties on NOx emission is smaller than the influence on PM emission. Some other fuels that have various side chain structures of 1-ring aromatics, normal paraffins only and various naphthene contents were also investigated.
Technical Paper

Novel Analysis Approach for Better Understanding of Fuel and Engine Effects on Diesel Exhaust Emission - JCAP Combustion Analysis Working Group Report Part II

2002-10-21
2002-01-2825
1 A novel analysis approach called “Regression Density method” was developed for better understanding of fuel property effects on exhaust emission. The approach was applied to diesel emission data obtained in JCAP programs and emission models were conducted to analyze the effects of fuel properties and engine conditions on emissions. By introducing this analysis method, the relationship between density factor and aromatics factor (chemical composition factor) was identified, however, they have been reported previously as dominant factors in fuel properties. The effects of engine conditions and fuel properties on emissions were investigated quantitatively based on the statistically conducted emission models to clarify universal ways to emission reduction. The mechanism of emission formation of vehicles and engines with characteristic behavior was also examined.
Technical Paper

Study of an Integrated Diesel Engine-CVT Control Algorithm for Improving Drivability and Exhaust Emission Performance

2001-10-01
2001-01-3452
Diesel engines have attracted more attention in recent years as one means of reducing carbon dioxide (CO2) emissions from motor vehicles. One of the major issues for diesel engines is exhaust emissions performance. Diesel engines also face various difficulties in providing the driving force demanded by the driver because of their greater inertia than that of gasoline engines. Meanwhile, continuously variable transmissions (CVTs) have been popularized as gearboxes that execute ratio changes continuously without generating shift shock. The aim of this research is to achieve higher levels of drivability and exhaust emissions performance by mating a CVT to a diesel engine and making maximum use of the continuous ratio change capability. An integrated engine-CVT control algorithm that can freely set the driving force and also the engine operating conditions for generating that driving force has been developed through this study.
Technical Paper

Development of a Gasoline-Fueled Vehicle with Zero Evaporative Emissions

2000-10-16
2000-01-2926
…Technologies for reducing evaporative emissions generated from gasoline vapors have been developed. To reduce evaporative emissions, both permeation from fuel and vapor lines and breakthrough from the evaporative canister need to be diminished. Fewer fuel line connections are used and hose and valve materials have been modified to reduce permeation. Component test results confirm that permeation is substantially reduced from the level of previous parts. A new type of activated charcoal, which has a high specific heat characteristic and improves adsorption and desorption performance, has been applied to reduce canister breakthrough. Additionally, the amount of purge air has been increased by applying purge control using an air-fuel ratio sensor. The problem of canister breakthrough has thus been resolved by the new evaporative canister combined with increased purge flow to the engine.
Technical Paper

JamaS Study on the Location of In-Vehicle Displays

2000-11-01
2000-01-C010
JAMA (Japan Automobile Manufactures Association, Inc.)'s guideline for car navigation systems is being decided on displayed the amount of information while driving. The position of a display and the estimated equation, which could be applied from a passenger car to a heavy truck, was studied. The evaluation index was the distance which drivers could become aware of a preceding vehicle by their peripheral vision, because car accidents while drivers glance at an in- vehicle display are almost the rear end collisions. As the results, the lower limit of a position of an in-vehicle display for a passenger car was 30 degrees, and a heavy truck was 46 degrees.
Technical Paper

Ultra-Clean Combustion Technology Combining a Low-Temperature and Premixed Combustion Concept for Meeting Future Emission Standards

2001-03-05
2001-01-0200
Experimental investigations were conducted with a direct-injection diesel engine to improve exhaust emission, especially nitrogen oxide (NOx) and particulate matter (PM), without increasing fuel consumption. As a result of this work, a new combustion concept, called Modulated Kinetics (MK) combustion, has been developed that reduces NOx and smoke simultaneously through low-temperature combustion and premixed combustion, respectively. The characteristics of a new combustion concept were investigated using a single cylinder DI diesel engine and combustion photographs. The low compression ratio, EGR cooling and high injection pressure was applied with a multi-cylinder test engine to accomplish premixed combustion at high load region. Combustion chamber specifications have been optimized to avoid the increase of cold-start HC emissions due to a low compression ratio.
Technical Paper

Technique for Analyzing Swirl Injectors of Direct-Injection Gasoline Engines

2001-03-05
2001-01-0964
This paper describes the numerical and experimental approaches that were applied to study swirl injectors that are widely used in direct-injection gasoline engines. As the numerical approach, the fuel and air flow inside an injector was first analyzed by using a two-phase flow analysis method [VOF (Volume of Fluid) model]. A time-series analysis was made of the flow though the injector and also of the air cavity that forms at the nozzle and influences fuel atomization. The calculated results made clear the process from initial spray formation to liquid film formation. Spray droplet formation was then analyzed with the synthesized spheroid particle (SSP) method. As the experimental approach, in order to measure the cavity factor that represents the liquid film thickness, nozzle exit flow velocities were measured by particle image velocimetry (PIV).
Technical Paper

Impact of Oil-derived Sulfur and Phosphorus on Diesel NOx Storage Reduction Catalyst - JCAP II Oil WG Report

2006-10-16
2006-01-3312
Emission regulations for diesel-powered vehicles have been gradually tightening. Installation of after-treatment devices such as diesel particulate filters (DPF), NOx storage reduction (NSR) catalysts, and so on is indispensable to satisfy rigorous limits of particulate matter (PM) and nitrogen oxides (NOx). Japan Clean Air Program II Oil Working Group (JCAPII Oil WG) has been investigating the effect of engine oil on advanced diesel after-treatment devices. First of all, we researched the impact of oil-derived ash on continuous regeneration-type diesel particulate filter (CR-DPF), and already reported that the less sulfated ash in oil gave rise to lower pressure drop across CR-DPF [1]. In this paper, impact of oil-derived sulfur and phosphorus on NSR catalyst was investigated using a 4L direct injection common-rail diesel engine with turbo-intercooler. This engine equipped with NSR catalyst meets the Japanese new short-term emission regulations.
Technical Paper

Effects of Fuel Properties on the Performance of Advanced Diesel NOx Aftertreatment Devices

2006-10-16
2006-01-3443
In the Japan Clean Air Program II (JCAP II) Diesel WG, effects of fuel properties on the performance of two types of diesel NOx emission aftertreatment devices, a Urea-SCR system and a NOx storage reduction (NSR) catalyst system, were examined. For a Urea-SCR system, the NOx emission reduction performance with and without an oxidation catalyst installed in front of the SCR catalyst at low exhaust gas temperature operation was compared. For an NSR catalyst system, the effect of fuel sulfur on both emissions and fuel economy during 50,000 km driving was examined. Furthermore, effects of other fuel properties such as distillation on exhaust emissions were investigated. The results show that sulfur is the influential factor for both devices. Namely, high NOx emission reduction performance of the Urea-SCR system with the oxidation catalyst at low exhaust gas temperature operation is influenced by sulfur.
Technical Paper

Investigations of Compatibility of ETBE Gasoline with Current Gasoline Vehicles

2006-10-16
2006-01-3381
Clarifying the impact of ETBE 8% blended fuel on current Japanese gasoline vehicles, under the Japan Clean Air Program II (JCAPII) we conducted exhaust emission tests, evaporative emission tests, durability tests on the exhaust after-treatment system, cold starting tests, and material immersion tests. ETBE 17% blended fuel was also investigated as a reference. The regulated exhaust emissions (CO, HC, and NOx) didn't increase with any increase of ETBE content in the fuel. In durability tests, no noticeable increase of exhaust emission after 40,000km was observed. In evaporative emissions tests, HSL (Hot Soak Loss) and DBL (Diurnal Breathing Loss) didn't increase. In cold starting tests, duration of cranking using ETBE 8% fuel was similar to that of ETBE 0%. In the material immersion tests, no influence of ETBE on these material properties was observed.
Technical Paper

A Study of an Analysis Method for Trace Substances in Vehicle Exhaust Gas

2007-04-16
2007-01-0306
A new method for measuring unregulated substances in the exhaust gas is being investigated to clarify the influence of the vehicles' exhaust emissions into the environment. This paper explains our work on developing an analysis method for detecting and quantifying trace substances in the exhaust gas. A new analysis method was examined that uses thermal desorption to analyze trace amounts of polycyclic aromatic hydrocarbons (PAHs) in vehicle exhaust gas. This technique is faster than conventional methods and does not require any preconditioning of the samples before analysis. While lead and chloromethane were detected in the exhaust gas samples, it was made clear that these substances did not originate in the engine system. Accordingly, the results of this study indicate that careful attention must be paid to the test environment and the presence of measurement interfering substances in exhaust samples when measuring trace constituents in the exhaust gas from low-emission vehicles.
Technical Paper

R&D and Analysis of Energy Consumption Improvement Factor for Advanced Clean Energy HEVs

2005-10-24
2005-01-3828
Ultra-low energy consumption and ultra-low emission vehicle technologies have been developed by combining petroleum-alternative clean energy with a hybrid electric vehicle (HEV) system. Their component technologies cover a wide range of vehicle types, such as passenger cars, delivery trucks, and city buses, adsorbed natural gas (ANG), compressed natural gas (CNG), and dimethyl ether (DME) as fuels, series (S-HEV) and series/parallel (SP-HEV) for hybrid types, and as energy storage systems (ESSs), flywheel batteries (FWBs), capacitors, and lithium-ion (Li-ion) batteries. Evaluation tests confirmed that the energy consumption of the developed vehicles is 1/2 of that of conventional diesel vehicles, and the exhaust emission levels are comparable to Japan's ultra-low emission vehicle (J-ULEV) level.
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