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With accelerating exhaust gas regulations in recent years, not only CO / HC / NOx but also PN regulation represented by Euro 6 d, China 6 are getting stricter. PN reduction by engine combustion technology development also progresses, but considering RDE, PN reduction by after treatment technology is also indispensable. To reduce PN exhausted from the gasoline engine, it is effective to equip GPF with a filter structure. Considering the installation of GPF in limited space, we developed a system that so far replaces the second TWC with GPF for the TWC 2 bed system. In order to replace the second TWC with GPF, we chose the coated GPF with filtering and TWC functions. Since the initial pressure drop and the catalyst amount (purification performance) of coated GPF have a conflicting relationship, we developed the coated GPF that can achieve both the low initial pressure drop and high purification performance.

To evaluate the relationship between the exhaust gas purification performance and the catalyst pore properties related to gas diffusion, an elementary reaction model was combined with gas diffusion into catalyst pores, referred to as the pseudo-2D gas diffusion/reaction model. It was constructed for Pt/Al2O3 + CeO2 catalyst as lean NOx catalyst. The gas diffusion was described as macro pore diffusion between the catalyst particles and meso pore diffusion within the particle. The kinetic model was composed of 26 reactions of NO/CO/O2 chemistry including 17 Pt/Al2O3 catalyst reactions and 9 CeO2 reactions. Arrhenius parameters were optimized using activity measurement results from various catalysts with various pore properties, meso pore volume and diameter, macro pore volume and diameter, particle size, and washcoat thickness. Good agreement was achieved between the measured and calculated values.

Lean-burn is an effective means of reducing CO2 emissions. To date, Homogenous Lean Charge Spark Ignition (HLSI) combustion, which lowers emissions of both CO2 and NOx, has been studied. Although HLSI realizes lower emission, it is a major challenge for lean-burn engines to meet SULEV regulations, so we have developed a new aftertreatment system for HLSI engines. It consists of three types of catalysts that have different functions, as well as special engine control methods. As the first stage in achieving SULEV emissions, this study focused on enhancing performance under lean conditions. HLSI engine exhaust gases contain high concentrations of hydrocarbons, including a large amount of paraffin, which are difficult to purify, rather than low concentrations of NOx. Therefore, the key point in low emissions is to purify not only NOx, but also high concentrations of paraffin at the same time.

The aim of this study is to clarify the mixture formation in the combustion chamber of our developed natural gas engine incorporating the sub-chamber injection system, in which natural gas is directly injected into a combustion sub-chamber in order to completely separate rich mixture in the sub-chamber, suitable for ignition, from ultra-lean mixture in the main chamber. Mixture distributions in chambers with and without sub-chamber were numerically simulated at a variety of operating conditions. The commercial software of Fluent 16.0 was used to conduct simulations based on Reynolds averaged Navier-Stokes equations in an axial 2 dimensional numerical domain considering movements of piston. Non-reactive flow in the combustion chamber was simulated before the ignition timing at an engine speed of 2000 rpm. The turbulence model employed here is standard k-ε model. Air-fuel ratio is set with a lean condition of 30.

Compression ignition combustion with a lean mixture has high potential in terms of high theoretical thermal efficiency and low NOx emission characteristics due to low combustion temperatures. In particular, a Dual-Fuel concept is proposed to achieve high ignition timing controllability and an extended operation range. This concept controls ignition timing by adjusting the fraction of two fuels with different ignition characteristics. However, a rapid combustion process after initial ignition cannot be avoided due to the homogenous nature of the fuel mixture, because the combustion process depends entirely on the high reaction rate of thermal ignition. In this study, the effect of mixture stratification in the cylinder on the combustion process after ignition based on the Dual-Fuel concept was investigated. Port injection of one fuel creates the homogeneous mixture, while direct injection of the other fuel prepares a stratified mixture in the cylinder at the compression stroke.

A new concept for trapping NOx and HC during cold start, the NOx Trap Three-Way Catalyst (N-TWC), is proposed. N-TWC adsorbs NOx at room temperature, and upon reaching activation temperature under suitable air-fuel ratio conditions, it reduces the adsorbed NOx. This allows a reduction in NOx emissions during cold start. N-TWC's reduction mechanism relies on NOx adsorption sites which are shown to be highly dispersed palladium on acid sites in the zeolite. Testing on an actual vehicle equipped with N-TWC confirmed that N-TWC is able to reduce emissions of NOx and HC during cold start, which is a challenge for conventional TWCs.

Catalyst simulation, which can analyze the complicated reaction pathway of exhaust gas purifications and identify the rate-determining step, is an essential tool in the development of catalyst materials. This requires an elementary reaction model which describes the detailed processes, i.e. adsorption, decomposition, and others. In our previous work, the elementary reaction model on Pt/CeO2 catalyst was constructed. In this study, we focused on extending the Zeolite catalyst and including the gas diffusivity through the catalyst layer. The reaction rate of a Zeolite catalyst was expressed by an Arrhenius equation, and the elementary reaction model was composed of 17 reactions. Each Arrhenius parameter was optimized by the catalytic activity measurements. The constructed model was validated with NOx conversion in cyclic experiments which were repeated with Lean phase (NOx adsorption) and Rich phase (NOx reduction).

This research is aimed at development of the catalyst for gasoline automobiles which uses only palladium (Pd) among platinum group metals (PGMs). And the conformity emission category aimed at LEV III-SULEV30. For evaluation, the improvement effect was verified for 2013 model year (MY) ACCORD (LEV II-SULEV) as the reference. As compared with Pd-rhodium (Rh) catalyst, a Pd-only catalyst had the low purification performance of nitrogen oxides (NOx), and there was a problem in the drop in dispersion of Pd by sintering, and phosphorus (P) poisoning.

In practical lean burn engines used to date, the use of a stratified air-fuel configuration, with a comparatively rich mixture in the vicinity of the spark plugs, has resulted in the stable combustion of an overall lean mixture. However, because a comparatively rich mixture is burned during the first half of combustion, NOx emissions are not reduced sufficiently. This research focused on a form of lean burn with homogeneous premixture that would be able to balance low NOx emissions with combustion controllability. It is widely known that homogeneous lean premixed gas has poor flame propagation characteristics. To determine the dominant cause of this, this study investigated the combustion properties of a single-cylinder engine while changing the compression ratio and intake temperature. As a result, the primary cause of combustion fluctuation, the abnormal cycle has a low TDC temperature compared to that of other cycles.

The reduction of NOx in exhaust gas has been a major challenge in diesel engine development. For the NOx reduction issues, a new Lean NOx Catalyst (LNC) aftertreatment system has been developed by Honda. A feature of the LNC system is the method that is used to reduce NOx through an NH₃-Selective Catalytic Reduction (NH₃-SCR). In an LNC system NOx is adsorbed at lean conditions, then converted to NH₃ at rich conditions and subsequently reduced in the next lean phase. In recent years, as the efficiency of the diesel engine has improved, the exhaust gas temperatures have been reduced gradually. Therefore, the aftertreatment system needs to be able to purify NOx at lower temperatures. The development of a new LNC which has a high activity at low temperature has been carried out. For the improvement of the LNC three material improvements were developed. The first of these was the development of a NOx adsorbent which is matching the targeted exhaust gas temperatures.

The field of diesel combustion research is producing numerous reports on studies of premixed combustion, which promises simultaneous reduction of both NOx and soot, in order to meet increasingly stringent regulations on harmful emissions from automobiles. However, although premixed combustion can simultaneously reduce both NOx and soot, certain issues have been pointed out, including the fact that it emits greater quantities of unburned HC and CO gases and the fact that it limits the operating range. Furthermore, this combustion method sets the ignition delay longer with the aim of promoting the mixing of fuel and air. This raises issues with the product due to the combustion instability and sensitivity to the uneven fuel properties that are found on the market, the capability of the engine response under transient conditions, the deterioration in combustion noise, and so on.

For reduction of NOx and soot emission with conventional diesel diffusion combustion, the authors focused on enhancement of the rate of injection (hereafter referred to as RoI) to improve air availability, thus enhancing the fuel distribution and atomization. In order to increase opening ramp of the RoI (hereafter referred to as fast injection rate), a hydraulic circuit was improved and nozzle geometries were optimized to make the greatest use of the advantages of the hydraulic circuit. Two different common rail injectors were prepared for this research. One is a mass production-type injector with piezo actuator that achieved the EURO-V exhaust gas emission standards, and the other is a prototype injector equipped with the new hydraulic circuit. The nozzle needle of the prototype injector is directly actuated by high-pressure fuel from common rail to improve the RoI.

Diesel engines offer better fuel economy compared to their gasoline counterpart, but simultaneous control of NOx and particulates is very challenging. The blended 2-way SCR/DPF is recently emerging as a compact and cost-effective technology to reduce NOx and particulates from diesel exhaust using a single aftertreatment device. By coating SCR catalysts on and inside the walls of the conventional wall-flow filter, the 2-way SCR/DPF eliminates the volume and mass of the conventional SCR device. Compared with the conventional diesel aftertreatment system with a SCR and a DPF, the 2-way SCR/DPF technology offers the potential of significant cost saving and packaging flexibility. In this study, an engine dynamometer test cell was set up to repeatedly load and regenerate the SCR/DPF devices to mimic catalyst aging experienced during periodic high-temperature soot regenerations in the real world.

A fully flexible valve actuation (FFVA) system was developed for a single cylinder research engine to investigate high efficiency clean combustion (HECC) in a diesel engine. The main objectives of the study were to examine the emissions, performance, and combustion characteristics of the engine using late intake valve closing (LIVC) to determine the benefits and limitations of this strategy to meet Tier 2 Bin 5 NOx requirements without after-treatment. The most significant benefit of LIVC is a reduction in particulates due to the longer ignition delay time and a subsequent reduction in local fuel rich combustion zones. More than a 95% reduction in particulates was observed at some operating conditions. Combustion noise was also reduced at low and medium loads due to slower heat release. Although it is difficult to assess the fuel economy benefits of LIVC using a single cylinder engine, LIVC shows the potential to improve the fuel economy through several approaches.

This paper presents a new substrate for Lean NOx Traps (LNT) which enables high NOx conversion efficiency, even after long-term aging, when using alkali metals as the NOx adsorber. When a conventional metal honeycomb is used as the LNT substrate, the chromium in the metal substrate migrates into the washcoat and reacts with the alkali metals after thermal aging. In order to help prevent this migration, we have developed a new substrate where a fine -alumina barrier is precipitated to the surface of the metal substrate. The new substrate is highly capable of preventing migration of chromium into the washcoat and greatly enhances the NOx conversion. The durability of the new substrate and emission test using a test vehicle are also examined.

In recent years, emission regulations have become more stringent as a result of increased environmental awareness in each region of the world. For diesel engines, reducing NOX emissions is a difficult technical challenge.[1],[2],[3],[4]. To respond to these strict regulations, an exhaust gas aftertreatment system was developed, featuring a lean NOX catalyst (LNC) that uses a new chemical reaction mechanism to reduce NOX. The feature of the new LNC is the way it reduces NOX through an NH3-selective catalytic reduction (SCR), in which NOX adsorbed in the lean mixture condition is converted to NH3 in the rich mixture condition and reduced in the following lean mixture condition. Thus, the new system allows the effective reduction of NOX. However, in order to realize cleaner emission gases, precise engine control in response to the state of the exhaust aftertreatment system is essential.

In recent years, emission regulations have become more stringent as a result of increased environmental awareness in each region of the world. For lean-burn diesel engines, since it is not possible to use three-way catalytic converters, reducing NOX emissions is a difficult technical challenge. To respond to these strict regulations, an exhaust gas aftertreatment system was developed, featuring a lean NOX catalyst (LNC) that uses a new chemical reaction mechanism to reduce NOX. The feature of the new LNC is the way it reduces NOX through an NH3-selective catalytic reduction (SCR), in which NOX adsorbed in the lean mixture condition is converted to NH3 in the rich mixture condition and reduced in the following lean mixture condition. Thus, the new system allows more efficient reduction of NOX than its conventional counterparts. However, an appropriate switching control between lean and rich mixture conditions along with compensation for catalyst deterioration was necessary.

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.

As technologies for simultaneously maintaining the current high thermal efficiency of diesel engines and reducing particulate matter (PM) and nitrogen oxide (NOX) emissions, many new combustion concepts have been proposed, including premixed charge compression ignition (PCCI) and low-temperature combustion[1]. However, it is well known that since such new combustion techniques precisely control combustion temperatures and local air-fuel ratios by varying the amount of air, the exhaust gas recirculation (EGR) ratio and the fuel injection timing, they have the issues of being less stable than conventional combustion techniques and of performance that is subject to variance in the fuel and driving conditions. This study concerns a system that addresses these issues by detecting the ignition timing with in-cylinder pressure sensors and by controlling the fuel injection timing and the amount of EGR for optimum combustion onboard.

This emission reduction technique has been researched on motorcycles equipped with a four-cylinder, liquid-cooled engine of 1100cm3 displacement in order to comply with the EURO-3 emission regulation. The EURO-3 emission regulation will be enforced in Europe beginning in year 2006. Compared to the EURO-2 regulation, reduction of cold-start HC and reduction of NOx from the extra-urban driving cycle are the main issues for EURO-3 compliance. The hydrocarbon reduction during cold-starting was achieved by the method of early catalyst activation using a combination of an Idle Air Control Valve system (IACV), ignition-retard, and atomization of fuel spray. In the extra-urban driving cycle, the fine controlled air-fuel ratio reduced. In addition, optimization of the number of three-way catalyst cells and their capacity also reduced NOx. Moreover, power loss decline caused by increased exhaust resistance due to increasing the catalyst size was avoided by optimizing the catalyst location.