ディーゼル排気中のPMを捕集する（DPF）は、目詰まり防止にPMを燃焼し除去する再生処理が必要となる。このとき、燃料増量によりDPFを高温状態にするため、燃費の悪化や後段SCR触媒の熱劣化が懸念される。本研究では、実路走行時の再生頻度、再生時の排出ガス挙動等を調査した。

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運送事業用の重量貨物車に、NOxセンサ等を用いた計測システム（SEMS）を装着し、長期間に渡り運送業務走行でのデータを取得した。これらのデータを基に、一般道走行、高速道路走行、アイドリング等の走行条件やDPF自動再生の頻度等を調査し、DPF自動再生の頻度とPM捕集性能の低下との関係について考察した。

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アッシュ堆積時の触媒付DPF上のPM酸化挙動を活性試験と可視化試験により解析した．アッシュ堆積がない場合，銀-セリア触媒付DPFは，白金/アルミナ触媒付DPFより約100℃低温でPMを酸化した．アッシュが堆積すると，後者はすぐに活性消失したが，前者はアッシュ堆積量40g/L，堆積厚さ100μm程度まで活性を発現した．

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一般財団法人日本自動車研究所（JARI）環境研究部が取り組んでいる研究領域の中から，カーボンニュートラルなモビリティ社会の実現に貢献すべく，環境負荷ゼロを目指した取り組み概要を紹介する．

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We propose a simple method of retrofitting common rail system to old diesel engine. Produce a boss connecting the injector and solenoid injector of 1DZ made by TOYOTA INDUSTRIES CORPORATION which is the testing institution of DENSO DCA - 25SPTH generator Process information from various sensors and send output signals to injector and tap supply pump to control injection quantity, injection time, injection rate and injection pressure. If changing from normal to common rail, NOx concentration decreased by about 51.3%. In addition, the NOx concentration was reduced by about 68.4% by multistage injection. Fuel efficiency improved by about 7.4% for single stage injection and about 8.4% for multistage injection. As experimental results, it was confirmed that the condition with the common rail system fitted reduced the NOx concentration. This is because the fuel is sprayed in the form of finer atomized fuel, it is inferred that this is a result that the common rail system was successfully retrofitted to the diesel engine of the generator. Because of the improved fuel economy, the technology of reducing the environmental load other than the common rail system. It is expected that environmental regulation can be cleared by using it.

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Factors which forms a flow field in an electrostatic precipitator (ESP) is a shape of ESP, a gas flow velocity and an ionic wind. Ionic wind is a flow that occurs ions generated by corona discharge collide with air molecules. About the influence on the particles of the ion wind, it is not clarified enough. It is important for the clarification of a particle collecting process, and improvement in particle collecting efficiency to clarify the interaction in ESP including an ion wind. In this study, it analyzed the particle behavior of ESP by using PIV (particle image velocimetry) analysis. The Particle Image Velocimetry method which can perform non-contact measurement and multi-point coincidence measurement was used for the analysis of a particle behavior. This paper reports a PIV analysis result about an ion wind and the particle movement velocity.

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In this study, formation process of deposit surface adhering on an EGR-simulated sample line was investigated using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Exhaust gas of a diesel engine passing through diesel particulate filter (DPF) was introduced into the sample line. Time-resolved infrared absorption spectra of the deposit were obtained for 6 hours from the beginning of the experiment including water condensation and evaporation process. Absorption peaks of C=O, C-H, and C=C caused by the hydrocarbon species on the surface of the deposit increase with increasing the deposition time. The change of the peak position in the DRIFTS spectra was not observed in formation process of the deposit. These findings suggest that EGR deposit were simply formed by condensation or adsorption of hydrocarbons having functional groups such as C=O, C-H, and C=C in exhaust gas.

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In this study, formation process of deposit adhering on an EGR simulated sample line was investigated using attenuated total reflection-Fourier transform infrared spectrometry (ATR-FTIR). Exhaust gas of a diesel engine passing through diesel particulate filter (DPF) was introduced into the sample line. Time-resolved infrared absorption spectra of the deposit were obtained for 6 hours from the beginning of the experiment including water condensation and evaporation process. Absorption peaks of C=O, C-H, and C=C were observed after condensed water has disappeared, and those absorption peaks increase with increasing the deposition time. The change of the ATR-FTIR spectra was not observed in formation process of the deposit. These findings suggest that EGR deposit were simply formed by condensation or adsorption of hydrocarbons having functional groups such as C=O, C-H, and C=C in exhaust gas.

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Emission standards for diesel engines have been tightened all over the world since diesel engine exhaust emissions contribute significantly to urban and global pollution. The use of fuel additive has been proposed as a cost-effective strategy for reducing pollutant emissions from diesel-powered engines. This paper introduces a possible mechanism of the catalytic reactions in the combination of platinum and cerium in diesel engine, and also shows an example of the actual use of a platinum-cerium bimetallic fuel additive for a diesel engine. Possible mechanism is suggested as follows; the soot oxidation occurs on Pt utilizing oxygen, and also occurs on Ce consuming nitrogen dioxide. A previous study showed that 54% of elemental carbon, 23% of organic carbon, and 34% of PM_2.5 were reduced when 0.13 ppm Pt and 7.5ppm Ce of the additive were used. The investigation of long-term effect for the diesel emission characteristics associated with the use of the fuel additive and other pollution control technologies is needed for further study.

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Nitrous oxide (N₂O) is a greenhouse gas and contributes to ozone depletion, and ammonia (NH₃) contributes to the formation of secondary particulate matter. To reduce global warming and particulate matter, the real-world levels of N₂O and NH₃ emitted from automobiles is required to be examined. However, there are a few studies on the measurements of N₂O and NH₃ in automobile exhaust under the real-world conditions. In this study, we have measured the real-world emissions of N₂O and NH₃ from the latest diesel vehicle equipped with an urea-SCR system. N₂O was measured by an on-board system using mid-IR laser spectroscopy and NH₃ was measured using a sensor-based measurement technique. As a result, NH₃ was not emitted, while N₂O was emitted intermittently when vehicle was running.

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DPF前後の圧力損失を予測するため，流入するAshの量，性状を予測することが必要である．そのため，実機エンジン試験によりPMを採取し，SEM，ICP等によりPM中Ashの成分，形状を分析した．その結果，Ash生成凝集過程を明らかにするとともに，排出されるAshの成分，粒子径，量等を予測した．

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This paper describes an online (real-time) optimization for control target values of NOx emission in diesel engine. Diesel engines are required to realize high efficiency and low fuel consumption while achieving exhaust emissions regulations which will become even more severe in the future. For that purpose, it is necessary to manage together the NOx reduction rate on the engine side and the aftertreatment system side. The target value manager performs online optimization based on the actual operating state of the engine and aftertreatment system. Online optimization uses a gradient method. By this method, the control target value that minimizes the operation cost (fuel and urea water) is calculated while suppressing the NOx emission to the regulated value or less. In addition, multi-objective particle swarm optimization is used to calibrate Lagrange multiplier parameters that affect NOx emissions and total operation cost, and Pareto optimal solutions for the two evaluation functions are obtained. This optimization improves the performance of the target value manager and visualizes tradeoffs between NOx emissions and total operating costs. The effectiveness of this approach is evaluated by simulation using data measured with a diesel engine test bench.

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石川県金沢市藤江の幹線道路脇において12年間（1999～2010年）の夏と冬の大気粉塵を捕集し、多環芳香族炭化水素（PAH）6種類（pyrene、benz[a]anthracene、chrysene、benzo[b]fluoranthene、benzo[k]fluoranthene、benzo[a]pyrene）およびニトロ多環芳香族炭化水素（NPAH）7種類（1,3-、1,6-、1,8-dinitropyrenes、1-nitropyrene、6-nitrochrysene、7-nitrobenz[a]anthracene、6-nitrobenzo[a]pyrene）をそれぞれHPLC-蛍光検出法、HPLC-化学発光検出法で測定し、その変遷を明らかにした。この間に、PAH濃度は冬63.9％、夏75.6％減少、NPAH濃度は冬88.0％、夏89.2％減少した。また[1-NP]/[Pyr]値は冬と夏ともに著しく減少した。自動車排ガス規制の強化によって排出源としての自動車の寄与率が低下したことが、大気中PAH、NPAH濃度および[1-NP]/[Pyr]値が顕著に減少した主要因と考えられた。

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From the viewpoint of hearing protection, many agricultural vehicles exceed the recommended value of acceptable noise level at noise exposure of 8 hours per day, suggesting the need to reduce noise. There is a shielding in the engine room as a measure against airborne sound due to surface vibration of the internal combustion engine. Particularly, in order to efficiently reduce noise, it is necessary to identify a highly contributing route in the sound transmission path from the noise source to the evaluation position represented by the operator's ear position and to shield the part in a part. As a method of identifying this sound transmission path, there is visualization of acoustic intensity indicating sound magnitude and directionality. As a visualization method, in this study, a sound source model that identifies the surface vibration velocity of the internal combustion engine is constructed, and the sound transmission path is predicted by calculating the acoustic intensity with the surface vibration velocity as an input. The sound source model is constructed by an acoustic transfer function calculated by the boundary element method and Inverse-Numerical Acoustic analysis which calculates the surface vibration velocity using the actual sound pressure measured at the field point near the sound source. Furthermore, the effectiveness of this method was confirmed by verifying the shielding method based on the sound transmission path and its effect both on the actual machine and numerical simulation. As a result, both the actual machine and the simulation showed the same value for the noise reduction amount at the operator's ear position. Therefore, the effectiveness of this method was shown.

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