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To reduce NOx and PM emissions in exhaust gas, after-treatment systems for low NOx emissions are being developed in combination with improvements of engine combustion. In recent years, the exhaust gas temperature has been dropping because of enhanced low-fuel consumption of the engine. Therefore, it is urgent to develop NOx reduction technologies that work at a low temperature under 200degC. Since NOx is reduced by reacting with ammonia supplied to the SCR catalyst, it is necessary to make the urea solution decompose into ammonia using the heat of the exhaust gas to supply sufficient ammonia to the SCR catalyst. However, both the decomposition reaction and hydrolysis reaction of the urea have insufficient exhaust heat, thus making it difficult for urea to decompose and hydrolyze to ammonia at a low temperature. To solve this problem, it focuses on forcibly decomposing the urea solution without depending on the exhaust gas temperature.

Achieving cleaner air throughout the world requires reducing diesel emissions. Therefore, after-treatment system without using a urea solution (DEF) called DPR-II has been developed in-house. It uses diesel fuel as a reducing agent (HC-SCR) to reduce NOx emission in diesel exhaust. The development of the fundamental technology could result in high NOx reduction performance at low to high temperature ranges, to meet the Japan 2016 emission regulation.

Urea-SCR(selective catalytic reduction) system is widely used as a technology of NOx(Nitrogen Oxides) reduction from diesel engine exhaust gases. Emission regulations have becoming stricter all over the world, and high NOx reduction performance is necessary to meet the emission regulations. To get higher NOx reduction performance of the Urea-SCR system, it is important to understand detailed chemical reaction mechanisms of Urea-SCR catalysts. In this study, we focused on elucidation of the reaction mechanism of the Urea-SCR catalyst by numerical simulation approach. The chemical reaction models with detail chemical reactions were built for both Fe-catalyst and Cu-catalyst. Both of the catalytic reaction models can predict difference of the catalytic reaction performance between the Fe-catalyst and the Cu-catalyst. In addition, rate-determining reaction step of the Cu-catalyst was successfully identified by the numerical simulation results.

Urea selective catalyst reduction (SCR) systems have a high NOx conversion rate because the ammonia formed by the hydrolyzing urea solution reacts with NOx efficiently as a reducing agent. Systems combining urea-SCR and a diesel particulate filter (DPF) have been adopted in heavy duty vehicles to meet the post new long term emissions regulations in Japan. This study examined the emissions reduction performance of these systems after 160,000 km. The emissions that were examined included both regulated emissions (NOx, PM, HC, and CO) and unregulated emissions. As a result, the cleanness of diesel emissions from a urea-SCR and DPF system was confirmed.

1 To meet the Japan Post New-Long-Term (Japan 2009) emissions regulation introduced in 2009, The Hydrocarbon Selective Catalytic Reduction (HC-SCR) system for the NOx emission with a diesel fuel was chosen among various deNOx after-treatment systems (the Urea-SCR, the NOx storage-Reduction Catalyst and so on). The HC-SCR was adopted, in addition to combustion modification of diesel engine (mainly cooled EGR) as the New DPR system. The New DPR system for medium and light duty vehicles was developed as a world's first technology by Hino Motors. Advantages of the New DPR are compact to easy-to-install catalyst converter and no urea solution (DEF) injection (regardless urea infrastructure) as compared the Urea-SCR system.

Diesel Particulate Filter (DPF) has become a standard after treatment device to remove particulate matter (PM) exhausted from diesel engines. Cordierite and Silicon Carbide are commonly used materials for construction of DPF. Customers, however, require further improvement concerning the performance of DPF. Cordierite has low limitation of PM loading capacity due to its lower thermal shock resistance, while silicon carbide has higher back-pressure due to its larger grain size. Generally, silicon nitride which is one of the typical thermal resistant ceramics has high mechanical strength and thermal shock resistance. Kubota's development of porous silicon nitride is structured with controlled small grain crystals of elongated hexagonal systems. This enables high PM filtration efficiency with low back pressure increase and higher filtering efficiencies for smaller PM.

The new Diesel Particulate active Reduction (DPR) system was developed for a medium-duty commercial vehicle as a deNOx catalyst combined with the conventional DPR system to achieve the Japan Post New-Long-Term (JPNLT) emissions regulations. It consists of a catalyst converter named as the new DPR cleaner, a fuel dosing injector, NOx sensors, temperatures and pressure sensors. The new DPR cleaner was constructed from a Front Diesel Oxidation Catalyst (F-DOC), a catalyzed particulate Filter (Filter), and a Rear Diesel Oxidation Catalyst (R-DOC). A newly developed Hydrocarbon Selective Catalyst Reduction (HC-SCR) catalyst was employed for each catalyst aiming to reduce NOx emissions with diesel fuel supplied from the fuel dosing injector. While the total volume of the catalyst was increased, the compact and easy-to-install catalyst converter was realized through the optimization of the flow vector and flow distribution in it by means of Computational Fluid Dynamics (CFD) analysis.

The emissions reduction potential of neat GTL (Gas to Liquids: Fischer-Tropsch synthetic gas-oil derived from natural gas) fuels has been preliminarily evaluated by three different latest-generation diesel engines with different displacements. In addition, differences in combustion phenomena between the GTL fuels and baseline diesel fuel have been observed by means of a single cylinder engine with optical access. From these findings, one of the engines has been modified to improve both exhaust emissions and fuel consumption simultaneously, assuming the use of neat GTL fuels. The conversion efficiency of the NOx (oxides of nitrogen) reduction catalyst has also been improved.

A 2-LEG NOx Storage-Reduction (NSR) catalyst system is one of potential after-treatment technology to meet stringent NOx and PM emissions standards as Post New Long Term (Japanese 2009 regulation) and US'10. Concerning NOx reduction using NSR catalyst, a secondary fuel injection is necessary to make fuel-rich exhaust condition during the NOx reduction, and causes its fuel penalty. Since fuel injected in the high-temperature (∼250 degrees Celsius) exhaust instantly reacts with oxygen in common diesel exhaust, the proportion of fuel consumption to reduce the NOx stored on NSR catalyst is relatively small. A 2-LEG NSR catalyst system has the decreasing exhaust flow mechanism during NOx reduction, and the potential to improve the NOx reduction and fuel penalty. Therefore, this paper studies the 2-LEG NSR catalyst system. The after-treatment system consists of NSR catalysts, a secondary fuel injection system, flow controlled valves and a Catalyzed Diesel Particulate Filter (CDPF).

Reducing the oxides of nitrogen (NOx) and particulate matter (PM) from Diesel engine exhaust gas has become very important problem in view of the protection of environment and the saying energy. But it is difficult to reduce both emissions significantly at the same time by engine modifications and operating condition control. Because, their characteristics have a trade off relation. Therefore many investigators are studying the aftertreatment technique of Diesel engine emissions such as a PM trap filter, EGR, etc. The aftertreatment technique is expected that engine operating condition limits will be loose and engine efficiency will be improved. A few years ago, Iwamoto showed that Zeolite catalyst could reduce the NOx with hydrocarbon reducing agents under oxygen rich condition[1]*. After that, many researchers have been investigating Zeolite catalysts[2]-[4].

Mechanical seals have been applied as sealing devices for water pumps of automotive engines. The mechanical seal plays an important state. Therefore, there are many kinds of constructions. This paper is concerned with the FEM (Finite Element Method) analytical results for various water pump seal construction. It becomes clear that the property of heat transfer is closely related to the sealing durability.

Many kinds of turbochargers have been mounted to engines for automotive use. Now, conventional, wastegated, variable geometry turbocharger and many systems are available. These turbocharged engines have many advantages, such as a high specific output power and good efficiency. Diesel engines are more suitable to turbocharging than spark ignition engines. But recently for a growing interest in acid rain and green house effect problems, regulations of engine exhaust gas emission have been tightened in Japan, USA and Europe. NOx and particulate matter from automotive engines must be reduced. In the USA, transient response of boost pressure has been important also for the EPA transient test mode. To cope with these regulations, diesel engine manufacturers demand turbocharger makers to provide far higher boost pressure than ever to supply more air to engines to improve combustion process.

A C-shaped seals is used under severe conditions in which rubber gasket and o-ring can not be used. Furthermore, C-seals exhibit various advantage such as small fitting space and light weight, therefore widely used as sealing elements for rocket engines and automotive engines. And also particular advantage offered by C-seals is good springback, high level of sealing performance under high pressure condition, stretching of the flange bolts. This paper is concerned of the sealing mechanism of C-seal by experimental work and finite element stress analysis. As a result, the lead coated layer on a C-seal has an important function on the sealing performance. In the present paper we describe on an interesting results reached by experiments regarding correlation of helium leakage late and contact pressure.

Mechanical seals have been applied as a sealing device for an automotive air conditioning compressor. Sometimes, the leaking trouble occurs under the conditions such as excessive wear, blistering formation and cracking phenomena on the carbon-ring. This paper is concerned with the analysis of cracking phenomena based upon Finite Element Method (FEM) calculation and experimental investigation.

Instead of end-face type seals, lip-type seals have recently been widely applied as sealing devices for automotive air conditioning compressors, and have shown good sealing performance in practical applications. This paper is concerned with the sealing phenomena of lip-type seals, which run under hydrodynamic lubrication between the lip/shaft surfaces.

C-shaped metal seals (C-seal) are used as static seals under the conditions such as high vacuum, high pressure, high temperature and cryogenic states. The correlation between the sealing performance and design parameters as loading force, deformation, and the surface roughness of ontacting faces have been investigated. This paper is concerned with the relationship between the surface condition of the coated-lead layer of C-seals and the surface roughness of mating flange. The effects of surface condition on leakage are examined fundamentally. Annular coated-lead layer on the surface of a C-seal prevents leakage, though there exist the fine defects or surface irregularities on the flange. It becomes clear from the test results that the surface conditions of the flange and loading force closely relate to the leakage rates with the deflection of C-seal under the. load and the behavior of the contact condition of flange surface.

Mechanical seals have been applied as a sealing device for an automotive air conditioning compressor. However, the leaking trouble occurs under the conditions such as excessive wear, blistering formation and cracking phenomena on the carbon-rings. This paper is concerned with a study of carbon-cracking phenomena.

The turbo-charger of an automotive engine is commonly used for increasing its power characteristics. In this equipment, both sealing and lubricating conditions are important factors and face to difficult technical problems. This paper is concerned with sealing problem for the turbo-charger, and development of low frictional type mechanical seals with good performance and excellent reliability.

The adoption of the newly developed self-standing grid construction allows a more flexible layout of the electrodes and location of the grids, while reducing the number of grid leads. These improvements make it possible to minimize the lead pitch and to increase the flexibility of the lead out position. For example, the leads of the new clip-on type displays will allow them to be condensed on one side of the display, while in the case of the ordinary Vacuum Fluorescent Displays (VFDs) the leads are located on both the top and the bottom. By connecting flat cables to the minimized leads, a clip-on VFD was successfully developed, which is excellent in terms of mounting flexibility, circuit maintenance, system cost and function. The manufacturing process and features of the clip-on VFD will be described later.

A lip seal for use in high-pressure automotive air conditioning compressors has been developed. This paper describes the design and the sealing performance of this new lip seal.