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Technical Paper

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

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

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

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

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

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)

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)

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

Direct Heat Loss to Combustion Chamber Walls in a D.I. Diesel Engine-Development of Measurement Technique and Evaluation of Direct Heat Loss to Cylinder Liner Wall

The purpose of this study is to clarify the state of heat loss to the cylinder liner of the tested engine of which piston and cylinder head were previously measured. The authors' group developed an original measurement technique of instantaneous surface temperature at the cylinder liner wall using thin-film thermocouples. The temperature was measured at 36 points in total. The instantaneous heat flux was calculated by heat transfer analysis using measurement results of the temperature at the wall. As a result, the heat loss ratio to all combustion chamber walls is evaluated except the intake and exhaust valves.
Technical Paper

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

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

…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

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

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

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

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

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

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

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

A Study for Understanding Carsickness Based on the Sensory Conflict Theory

Two hypotheses based on the sensory conflict theory were postulated as possible means for reducing carsickness: (1) Reducing signals from the vestibular and vision systems through a reduction of low-frequency motion would mitigate carsickness and (2) Controlling stimulation of visual organs so as to reduce the amount of sensory conflict would mitigate carsickness. For hypothesis (1), the relations between subjective carsickness ratings and motions of the vehicle and passengers' body were investigated. Greater correlation was found between carsickness ratings and motions of the passengers' head, where the organs of the vestibular and vision systems are located, than between carsickness ratings and vehicle motions. For hypothesis (2), the incidence of carsickness in passengers who gazed at an in-vehicle display was investigated because there seemed to be large conflict between the vestibular system and the vision system.
Technical Paper

Development of a New 5.6L Nissan V8 Gasoline Engine

This paper describes a new 5.6-liter DOHC V8 engine, VK56DE, which was developed for use on a new full-size sport utility vehicle and a full-size pickup truck. To meet the demands for acceleration performance when merging into freeway traffic, passing or re-acceleration performance from low speed in city driving and hill-climbing or passing performance when towing, the VK56DE engine produces high output power at top speed and also generates ample torque at low and middle engine speeds (90% of its maximum torque is available at speeds as low as 2500 rpm). Furthermore, this engine achieves top-level driving comfort in its class as a result of being derived from the VK45DE engine that was developed for use on a sporty luxury sedan. Development efforts were focused on how to balance the required performance with the need for quietness and smoothness.
Technical Paper

Impact of Oil-derived Ash on Continuous Regeneration-type Diesel Particulate Filter - JCAPII Oil WG Report

Impact of oil-derived ash on the pressure drop of continuous regeneration-type diesel particulate filter (CR-DPF) was investigated through 600hrs running test at maximum power point on a 6.9L diesel engine, which meets the Japanese long-term emission regulations enacted in 1998, using approximately 50ppm sulfur content fuel. Sulfated ash content of test oils were varied as 0.96, 1.31, and 1.70 mass%, respectively. During the running test, the exhaust pressure drop through CR-DPF was measured. And after the test, the ventilation resistance through CR-DPF was also evaluated before and after the baking process, which was applied to eliminate the effect of soot accumulated in CR-DPF. The results revealed that the less sulfated ash in oil gave rise to lower pressure drop across CR-DPF. According to microscope examination of the baked DPF, ash was mainly accumulated on the wall surface of CR-DPF, and that seemed to be related to the magnitude of pressure drop caused by ash.
Technical Paper

HCCI Combustion on a Diesel VCR Engine

A variable compression ratio (VCR) technology, that has a new piston-crankshaft mechanism with multi links, has been patented and developed by Nissan for some years (This technology has been detailed in previous SAE paper 2003-01-0921 and 2005-01-1134). This paper will present the use of this VCR technology for Diesel engine. The objective set with the use of VCR for Diesel engine is mainly to reduce as much as possible engine out emission to prepare for long-term, more strict emission standards. Results presented will include the description of the 2l Diesel VCR engine and its VCR mechanism adapted to Diesel constraints. Combustion tests have been performed with the use of HCCI (Homogeneous Charge Compression Ignition) combustion. This technology is still in a research phase in Renault: the adaptation of VCR technology to a Diesel engine consists in the modification of several parts with the addition of lower links, control links and control shaft.