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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.

Due to its better fuel efficiency and low CO2 emissions, the number of diesel engine vehicles is increasing worldwide. Since they have high Particulate Matter (PM) emissions, tighter emission regulations will be enforced in Europe, the US, and Japan over the coming years. The Diesel Particulate Filter (DPF) has made it possible to meet the tighter regulations and Silicon Carbide and Cordierite DPF's have been applied to various vehicles from passenger cars to heavy-duty trucks. However, it has been reported that nano-size PM has a harmful effect on human health. Therefore, it is desirable that PM regulations should be tightened. This paper will describe the influence of the DPF material characteristics on PM filtration efficiency and emissions levels, in addition to pressure drop.

Reducing the fuel consumption of powertrains in internal combustion engines is still a major objective from an environmental viewpoint. Internal combustion engines waste a huge part of the fuel energy as heat in the exhaust line. Currently, exhaust heat recovery (EHR) systems are attracting attention as an effective means of reducing fuel consumption by collecting heat from waste exhaust gas and using it for rapid warming up of the engine and cabin heating [1, 2, 3, 4]. The benefits of the EHR system are affected by a trade-off between the efficacy of the recovered useful thermal energy and the adverse effect of the additional weight (heat mass) of the system [5]. Conventional EHR systems have a complex heat exchanger structure and a structure in which a bypass pipe and heat exchanger are connected in parallel, giving them a large size and heavy weight. We have developed a new-concept silicon carbide (SiC) heat exchanger with a dense SiC honeycomb.

HC emission standards will be tightened during the 1990's in the US. A key issue in reducing HC emission is improving the warm-up characteristics of catalysts during the cold start of engines. For this purpose, studies are under way on reduction of heat mass of ceramic substrates. Reduction of cell walls in substrates to thickness smaller than the current thickness of 12mil or 6mil has resulted in reduced heat mass, and also reduced flow restriction of substrates. The warm-up characteristics of low bulk density catalysts are better than those of high bulk density, i.e., the warm-up characteristics of thinner wall or lower cell density catalysts are better than those of thicker wall or higher cell density catalysts. A relationship between geometric surface area and warm-up characteristics is observed.

In this study, to satisfy increasingly strict emission regulations, the conversion efficiency of a 0.11 mm (4 mil) thin-wall catalyst is discussed. The effects of catalyst bulk density on reducing heat mass to improve catalyst emission conversion in the early cold transient mode (Bag 1 in the FTP-75 mode) is quantitatively discussed. To analyze the effects of low heat mass, catalyst's bed temperatures were measured. Effects of the geometric surface area (GSA) and volume of the catalyst were also analyzed. An early feedback control system with an HEGO oxygen sensor and a secondary air injection control system with an original oxygen sensor were compared with an original control system on THC, CO, and NOx emission amounts.

Catalytic performance can be improved by increasing geometric surface area (GSA) and reducing bulk density (BD), namely heat capacity, using high cell-density / thinwall advanced ceramic substrates. The advanced substrates, such as 3 mil/600 cpsi and 2 mil/900 cpsi have improved the catalytic performance over the conventional substrates, and are expected to help in complying with future emission regulations, as well as catalyst downsizing. This paper describes the effects of GSA and BD using Pd-based catalysts. The reduction of hydrocarbons emissions was demonstrated significantly at close-coupled location, and dual bed design was proven effective. The effectiveness at under-floor location was not as significant as the close-coupled location.

Heavy Duty Vehicle (HDV) Diesel emission regulations are set to be tightened in the future. The introduction of PN PEMS testing for Euro VI-e, and the expected tightening of PM/NOx targets set to be introduced by CARB in the US beyond 2024 are expected to create challenging tailpipe PN conditions for OEMs. Additionally, warranty and the useful life period will be extended from current levels. Improved fuel efficiency (reduction of CO2) also remains an important performance criteria. Furthermore, future non-road diesel emission regulations may follow tighten HDV diesel emission regulations contents, and non-road cycles evaluation needs to be considered as well for future. In response to the above tightened regulation, for Diesel Particulate Filter (DPF) technologies will require higher PN filtration performance, lower pressure drop, higher ash capacity and better pressure drop hysteresis for improved soot detectability.

The engine performance and emissions characteristics of a single-cylinder DI diesel engine were experimentally investigated. The combustion chamber walls of the engine were thermally insulated with ceramic materials of SSN (Sintered Silicon Nitride) and PSZ (Partially Stabilized Zirconia). Fuel economy and emissions characteristics were improved by insulating selected locations of the combustion chamber walls. The selective insulation helped to create activated diffusion combustion and resulted in more efficient use of the intake air.

In applying ceramic honeycomb wall flow type filters to the after-treatment systems of diesel particulate from engines, the melting and thermal shock failures of ceramic diesel particulate filters (DPF) have been considered as one of the most significant issues during regeneration. This paper gives the results of experiments on the effects of cell structure i.e., wall thickness and cell density, on the melting and thermal shock regeneration failure of DPF and proposes an optimized cell structure for DPF in terms of the regeneration failure and the pressure drop which is also considered to be one of the especially important issues in fuel economy for heavy duty vehicle application.

Regulatory compliance measurements for vehicle emissions are generally performed in well equipped test facilities using chassis dynamometers that simulate on-road conditions. There is also a requirement for obtaining accurate information from vehicles as they operate on the road. An on-board system has been developed to measure real-time mass emission of NOx, fuel consumption, road load, and engine output. The system consists of a dedicated data recorder and a variety of sensors that measure air-to-fuel ratios, NOx concentrations, intake air flow rates, and ambient temperature, pressure and humidity. The system can be placed on the passenger seat and operate without external power. This paper describes in detail the configuration and signal processing techniques used by the on-board measurement system. The authors explain the methods and algorithms used to obtain (1) real-time mass emission of NOx, (2) real-time fuel consumption, (3) road load, and (4) engine output.

An exhaust heat recovery (EHR) system is an effective and attractive means of improving fuel economy and in-vehicle comfort, especially of hybrid cars in winter. However, many conventional bypass systems, which have a bypass pipe and bypass valve with a thermal actuator, are still large and heavy, and it is necessary not only to effectively improve the heat recovery but also to minimize the size and weight of EHR systems. Sakuma et al. reported new-concept heat exchangers and EHR systems using a highly heat-conductive SiC honeycomb, including a non-bypass system. However, since this non-bypass system always recovers heat from the exhaust gas, its heat recovery performance was set so as not to exceed the cooling capability of the radiator at a high engine load to prevent overheating of the vehicle.

The DPF(Diesel Particulate Filter) has been established as a key technology in reducing diesel PM emission. Also Catalyzed-DPF Systems are viewed as the next generation DPF System in the automotive sector, replacing the current Fuel Additive System. The performance requirements of the DPF-equipped vehicle are good fuel economy, good driving performance, high PM regeneration performance of accumulated soot and high durability. In this paper the effect of Catalyzed-DPF characteristics, such as porosity, pore size, cell structure and catalyst loading have been defined on pressure drop, filtration efficiency, regeneration efficiency and regeneration behavior.