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Particle Number (PN) regulation was firstly introduced for European light-duty diesel vehicles back in 2011[1]. Since then, PN regulation has been and is being expanded to heavy-duty diesel vehicles and non-road diesel machineries. PN regulation will also be expanded to China and India around 2020 or later. Diesel Particulate Filter (DPF) is significant factor for the above-mentioned PN regulation. This filter technology is to be continuously evolved for the near future tighter PN regulation. Generally, PN filtration performance test for filter technology development is carried out with chassis dynamometer, engine dynamometer or simulator [2]. This paper describes a simplified and relatively quicker alternative PN filtration performance test method for accelerating filter technology development compared to the current test method.

Diesel engines are widely used to reduce CO2 emission due to its higher thermal efficiency over gasoline engines. Considering long term CO2 targets, as well as tighter gas emission, especially NOx, diesel engines must become cleaner and more efficient. However, there is a tradeoff between CO2 and NOx and, naturally, engine developers choose lower CO2 because NOx can be reduced by a catalytic converter, such as a SCR catalyst. Lower CO2 engine calibration, unfortunately, leads to lower exhaust gas temperatures, which delays the activation of the catalytic converter. In order to overcome both problems, higher engine out NOx emission and lower exhaust gas temperatures, close-coupled a diesel particulate filter (DPF) system with integration of SCR catalyst technology is preferred. For SCR catalyst activity, it is known that the catalyst loading amount has an influence on NOx performance, so a high SCR catalyst loading will be required.

Since the implementation of Euro 6 in September 2014, diesel engines are facing another drastic reduction of NOx emission limits from 180 to only 80 mg/km during NEDC and real driving emissions (RDE) are going to be monitored until limit values are enforced from September 2017. Considering also long term CO2 targets of 95 g/km beyond 2020, diesel engines must become cleaner and more efficient. However, there is a tradeoff between NOx and CO2 and, naturally, engine developers choose lower CO2 because NOx can be reduced by additional devices such as EGR or a catalytic converter. Lower CO2 engine calibration, unfortunately, leads to lower exhaust gas temperatures, which delays the activation of the catalytic converter. In order to overcome both problems, higher NOx engine out emission and lower exhaust gas temperatures, new aftertreatment systems will incorporate close-coupled DeNOx systems.

A Particle Number (PN) limit for Gasoline Direct Injection (GDI) vehicles was introduced in Europe from September 2014 (Euro 6b). In addition, further certification to Real Driving Emissions (RDE) is planned [1] [2], which requires low and stable emissions in a wide range of engine operation, which must be durable for at least 160,000 km. To achieve such stringent targets, a ceramic wall-flow Gasoline Particulate Filter (GPF) is one potential emission control device. This paper focuses on a catalyzed GPF, combining particle trapping and catalytic conversion into a single device. The main parameters to be considered when introducing this technology are filtration efficiency, pressure drop and catalytic conversion. This paper portrays a detailed study starting from the choice of material recipe, design optimization, engine bench evaluation, and final validation inside a standard vehicle from the market during an extensive field test up to 160,000 km on public roads.

The automotive industry is currently evaluating the gasoline particulate filter (GPF) as a potential technology to reduce particulate emissions from gasoline direct injection (GDI) engines. In this paper, several GPF design measures which were taken to obtain a filter with lower pressure drop when compared to our previous concept will be presented. Based on engine test bench and vehicle test results, it was determined some soot will accumulate on the GPF walls, resulting in an increase in pressure drop. However, the accumulated soot will be combusted under high temperature and high O₂ concentration conditions. In a typical vehicle application, passive regeneration will likely occur and a cycle of soot accumulation and combustion might be repeated in the actual driving conditions.

Diesel engines are more fuel efficient due to their high thermal efficiency, compared to gasoline engines and therefore, have a higher potential to reduce CO2 emissions. Since diesel engines emit higher amounts of Particulate Matter (PM), DPF systems have been introduced. Today, DPF systems have become a standard technology. Nevertheless, with more stringent NOx emission limits and CO2 targets, additional NOx emission control is needed. For high NOx conversion efficiency, SCR catalysts technology shows high potential. Due to higher temperature at the close coupled position and space restrictions, an integrated SCR concept on the DPFs is preferred. A high SCR catalyst loading will be required to have high conversion efficiency over a wide range of engine operations which causes high pressure for conventional DPF materials.

Ammonia Selective Catalytic Reduction (SCR) and Lean NOx Trap (LNT) systems are key technologies to reduce NOx emission for diesel on-highway vehicles to meet worldwide tighter emission regulations. In addition DeNOx catalysts have already been applied to several commercial off-road applications. Adding the DeNOx catalyst to existing Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) emission control system requires additional space and will result in an increase of emission system back pressure. Therefore it is necessary to address optimizing the DeNOx catalyst in regards to back pressure and downsizing. Recently, extruded zeolite for DeNOx application has been considered. This technology improves NOx conversion at low temperature due to the high catalyst amount. However, this technology has concerned about strength and robustness, because the honeycomb body is composed of catalyst.

The Inlet-Membrane DPF, which has a small pore size membrane formed on the inlet side of the body wall, has been developed as a next generation diesel particulate filter (DPF). It simultaneously achieves low pressure drop, small pressure drop hysteresis, high robustness, and high filtration efficiency. Low pressure drop improves fuel economy. Small pressure drop hysteresis has the potential to extend the regeneration interval since the linear relationship between pressure drop and accumulated soot mass improves the accuracy of soot mass detection by means of the pressure drop values. The Inlet-membrane DPF's high robustness also extends the regeneration interval resulting in improved fuel economy and a lower risk of oil dilution while its high filtration efficiency reduces PM emissions. The concept of the Inlet-Membrane DPF was confirmed using disc type filters in 2008 and its performance was evaluated using full block samples in 2009.

Gasoline Direct Injection (GDI) engines achieve better fuel economy but have the drawback of increased Particulate Matter (PM) emissions. As known from diesel engine applications particulate filters are an effective PM reduction device which is expected to be effective for reduction of particulates emitted by GDI engines as well. For this investigation new filter concepts especially designed for GDI applications are proposed. Filtration efficiency, pressure drop and regeneration performance were verified by cold flow bench and engine and chassis dynamometer testing. The experimental data were used to discuss the validity of these new filter design concepts.

Although diesel engines are superior to gasoline engines in terms of the demand to reduce CO2 emissions, diesel engines suffer from the problem of emitting Particulate Matter (PM). Therefore, a Diesel Particulate Filter (DPF) has to be fitted in the engine exhaust aftertreatment system. From the viewpoint of reducing CO2 emissions, there is a strong demand to reduce the exhaust system pressure drop and for DPF designs that are able to help reduce the pressure drop. A wall flow DPF having a novel wall pore structure design for reducing pressure drop, increasing robustness and increasing filtration efficiency is presented. The filter offers a linear relationship between PM loading and pressure drop, offering lower pressure drop and greater accuracy in estimating the accumulated PM amount from pressure drop. First, basic experiments were performed on small plate test samples having various pore structure designs.

A wall flow diesel particulate filter (DPF) having a novel wall pore structure design for reducing backpressure, increasing robustness, and increasing filtration efficiency is presented. The filter offers a linear relationship between soot loading and backpressure, offering greater accuracy in estimating the amount of soot loading from backpressure. Basic experiments were performed on small plate test pieces having various pore structure designs. Soot generated by a Cast-2F propane burner having a controlled size distribution was used. Cold flow test equipment that was carefully designed for flow distribution and soot/air mixing was used for precise measurement of backpressure during soot loading. The upstream and downstream PM numbers were counted by Scanning Mobility Particle Sizer (SMPS) to determine soot concentration in the gas flow and filtration efficiency of the test pieces. Microscope observations of the soot trapped in the wall were also carried out.

In this paper a method of DPF(Diesel Particulate Filter) lifetime estimation against the thermal stress is presented. In the method, experimentally measured material fatigue property and DPF temperature distributions under various conditions including regeneration mode were used to perform FEM stress analyses and the estimation of DPF lifetime and allowable stresses. From the viewpoint of the system design, to prevent DPF damages such as cracks created through thermal stress or melting, controlling the amount of PM accumulation is important. In this study, the pressure difference behavior under each of PM accumulation mode and regeneration mode was investigated experimentally. The experimental results showed different pressure drop behaviors in accumulation and regeneration. DPFs were observed in detail after PM accumulation and during regeneration to discuss mechanisms of the pressure difference behavior.