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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.

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).

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.

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.

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.

The mechanical seal in automotive water pumps is critical to the performance and reliability of the engine, requiring consistent, effective sealing performance and long operating life. In recent years, the advent of maintenance free performance requirements and increasingly severe operating conditions have resulted in significant changes to the variety and concentration of additives in cooling systems. As a consequence of these changes to the additives, various types of premature seal leakage failures have occurred during service operation. These have been categorized into four types of failure modes and compared with seals providing normal service in order to establish simulated test conditions for engine coolants containing various additives. This paper reports on the various types of failure mechanisms that were found to occur during simulated performance testing and the corrective measures that will eliminate their occurrence

End-face type seals have been applied as sealing devices for the water pumps in the cooling systems of automotive engines. However, many troublesome problems have occurred for many years and the countermeasures have been investigated as many times. For examples, the problem of excessive abrasion of seal faces caused by foreign particles in liquid to be sealed was solved by using the sliding materials which had a hither thermal conductivity and a lower coefficient of thermal expansion. Furthermore, the noise problem of the ringing phenomena caused by the stick-slip between sliding surfaces was prevented by changing the carbon material whose lubrication characteristics had a negative slope as weak as possible in the Torque-Speed curve. As a result of these investigations, end face seals of this type have obtained the satisfactory sealing performance for many users' requirements in the present Japanese market.

Recently, use of superchargers has been popularized as a means of improving output of passenger car engines. Supercharging is not a new problem. Gottlieb Daimler published an idea to supercharge a gasoline engine by a mechanically driven superchager in 1885 in DRP 34926 (Ref. 1)*. Two types of supercharging are used currently; turbo supercharging and mechanical supercharging. Turbo superchargers (exhaust gas turbine superchargers) are used in most case, however, have a weak point that the supercharging effect at a low speed is very small. For low speed operation, mechanical superchargers which can improve, this weak point greatly, are rather preferable to be used. However, they have several disadvantages, such as, with an increase in speed, power loss increases, delivery air temperature rises, delivery air density lowers, and so on. For automotive engine superchargers, it is necessary to overcome these problems.

There are various types of super chargers applied for mechanical charging system. Root system is the typical one of them, comprising some varieties such as vane type, spiral type, lysholm type, etc., each of which contains problems of consuming power, heat generation, wear- or other. It is now a big issue for the industry to overcome such problems and this paper refers to the effect of the vane type super charger (ESC-300) which could minimize such problems as less as possible.