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This paper proposes a high temperature manifold converter with a thin wall ceramic substrate, such as; 4mil/400cpsi and 4mil/600cpsi. Double-wall cone insulation design was proposed for close-coupled converters to protect the conventional intumescent mat from high temperature. However, the double wall cone insulation is not applicable when the converter is directly mounted to the exhaust manifold without an inlet cone. The prototype manifold converter was tested under hot vibration test with a non-intumescent ceramic fiber mat and retainer rings as a supplemental support. The converter demonstrated durability for 10 hours under 80G acceleration and 100 hours under 60G acceleration with 1,050 °C catalyst bed temperature. The skin temperature of the heat shield was kept below 400 °C.

In order to meet the strict automobile emission regulations in the U.S.A. and Europe, new aftertreatment technologies such as the EHC and HC Adsorber have been developed to reduce the cold start emissions. The EHC is obviously effective in reducing emissions, but has the demerits of a large electric power demand and a complicated power control system to support it (13). A by-pass type HC adsorber system has the concerns of unreliable by-pass valves and complicated plumbing (10). A major technical challenge of the in-line type HC adsorber was the difference between the HC desorption temperature and the light-off temperature of the burn-off catalyst. This paper describes the evaluation results of a completely passive “In-line HC Adsorber System” which can reduce the cold start emissions without the application of any type of mechanical or pneumatic control valve in the exhaust system.

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.

Thermal shock failures have been considered as one of the most significant issues for wall flow type ceramic diesel particulate filters during their regeneration. This paper describes the experiments which were conducted in order to study effects of heating rates of the accumulated diesel particulate on the thermal shock failure of the filters using an NGK soot generator. The results showed favorable heating rates of the particulate in terms of the amounts of the accumulated particulate up to which the filters are safely regenerated.

The effect on engine performance of insulating combustion chambers was simulated for a turbocharged direct injection diesel engine. We developed a low heat rejection (LHR) diesel cycle simulation. It includes a gas flow model, a heat transfer model, and a two zone combustion model. In the heat transfer model, convective and radiation heat transfer between the gas and walls was computed, taking into account the combustion chamber surface temperature swings. In the combustion model's combustion zone, the temperature and the chemical equilibrium compositions were determined. They were used to calculate the NO formation rate by assuming a modified Zeldvich mechanism. The combustion zone temperature was also used to estimate the radiation heat transfer. Simulations were performed of various combustion chamber surface materials and various LHR levels. The factors which affect thermal efficiency and exhaust emissions were deduced and their influences discussed.

The application of Diesel Particulate Filters (DPF's) is expanding in the European, Japanese and US markets to comply with the tighter PM regulations. SiC DPF's, featuring greater robustness, have been applied extensively to passenger cars and are expanding into larger sizes for Light Duty Trucks applications. The SiC-DPF has higher mechanical strength when compared to other materials, such as Cordierite. However, SiC's thermal expansion ratio is greater. Therefore, the SiC-DPF is designed with 35 X 35mm segments and cement bonded construction, both of which function to relieve thermal stress. The appearance of the SiC-DPF with the segment design is shown in Figure 1. In this paper, the thermal stress mechanism of the segmented joint during soot regeneration and the influence of the cement properties on the thermal shock resistance was investigated by using the soot regeneration model and thermal stress analysis in addition to the engine test.

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.

Although air pollution has mitigated since the introduction of exhaust emission regulations, further reduction of it especially in the metropolitan areas is anticipated. An effective way to resolve this issue is to improve the catalyst performance. Of many approaches, improving substrate is one promising way to achieve this goal. Results of applying high cell density and light- weight substrates, coupled with high precious metal content, are discussed theoretically and verified experimentally here. The significant improvements made in the low temperature activity and warmed-up conversions by increasing geometrical surface areas and lowering thermal mass of high cell density substrates are described.

This paper describes improvements achieved with regard to the long term stability and the system integrability of a previously described thick film NOx sensor for gasoline lean burn and diesel applications. (1, 2, 3) Durability test up to 1000 hours consisting of a temperature cycle have been carried out by a stoichiometric operating gasoline engine test bench. The NOx sensor demonstrates the NOx output shift in terms of the NOx sensitivity less than 5 % on a model gas apparatus and ± 7 % measuring accuracy in practical operating condition on a diesel engine after 1000 hours that is equivalent to approximately 60K miles driving. The integration of the control electronics for the sensor in its connector is achieved for the sensitive measuring current in the μA-range or less on vehicle applications. The developed electronics functions closed-loop controls for a tip temperature and oxygen pumps as well as a diagnosis of sensor malfunctions.

New ultra-low vehicle emission legislation requires advanced catalyst systems to achieve high conversion requirements. Manufacturers have to improve both the washcoat formulations and the catalyst substrate technology to meet these new regulations. This paper will present the results of a computer modeling study on the effects of ultra-thinwall catalysts on hydrocarbon and carbon monoxide light-off performance improvement. The experimental data from catalyst light-off testing on an engine dynamometer are compared with theoretical results of advanced substrate modeling for ultra-thin wall ceramic substrates. Results show that thermal mass has the greatest effect on light-off performance. Decreases in wall thickness offer the greatest benefit to light-off performance by lowering the thermal mass of the substrate, thus allowing it to reach light-off temperature faster.

In order to meet the challenging CO2 targets beyond 2020 without sacrificing performance, Gasoline Direct Injection (GDI) technology, in combination with turbo charging technology, is expanding in the automotive industry. However, while this technology does provide a significant CO2 reduction, one side effect is increased Particle Number (PN) emission. As a result, from September 2017, GDI vehicles in Europe are required to meet the stringent PN emission limits of 6x1011 #/km under the Worldwide harmonized Light vehicles Test Procedure (WLTP). In addition, it is required to meet PN emission of 9x1011 #/km under Real Driving Emission (RDE) testing, which includes a Conformity Factor (CF) of 1.5 to account for current measurement inaccuracies on the road. This introduction of RDE testing in Europe and China will especially provide a unique challenge for the design of exhaust after-treatment systems due to its wide boundary conditions.

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.

Selective catalyst reduction (SCR) using cordierite honeycomb substrate is generally used as a DeNOx catalyst for diesel engines exhaust in both on-road and commercial off-highway vehicles to meet today’s worldwide emission regulations. Worldwide NOx emission regulations will become stricter, as represented by CARB2027 and EuroVII. Technologies which can achieve further lower NOx emissions are required. Recently, several technologies, like increased SCR catalyst loading amount on honeycomb substrates, and additional SCR catalyst volume in positions closer to the engine are being considered to achieve ultra-low NOx emissions. However, undesirable pressure drop increase and enlarging after treatment systems will be caused by adopting these technologies. Therefore, optimization of the material and honeycomb cell structure for SCR is inevitable to achieve ultra-low NOx emissions, while minimizing any system drawbacks.

The LDV gasoline emission regulation is set to be tightened for Euro7. In particular, the particulate number (PN) requirement has been significantly tightened requiring a GPF with extra - high filtration efficiency to meet the target requirement. In order to meet the stricter PN requirements, GPF substrate material improvement is necessary. However, conventional GPF material improvement for high filtration efficiency will increase the filter backpressure significantly. The relationship between pressure drop and CO2 emission is difficult to quantify but high pressure drop can potentially increase the CO2 emission. Therefore, Membrane Technology (MT) is the key to break through the trade-off between filtration performance and pressure drop. MT is thin and dense layer of small grains applied on the GPF surface. MT application can increase particulate filtration efficiency significantly with minimal pressure drop increase.

This paper, written in collaboration with Ford, evaluates the effectiveness of higher cell density combined with higher porosity, lower thermal mass substrates for emission control capability on a customized, RDE (Real Driving Emissions)-type of test cycle run on a chassis dynamometer using a gasoline passenger car fitted with a three-way catalyst (TWC) system. Cold-start emissions contribute most of the emissions control challenge, especially in the case of a very rigorous cold-start. The majority of tailpipe emissions occur during the first 30 seconds of the drive cycle. For the early engine startup phase, higher porosity substrates are developed as one part of the solution. In addition, further emission improvement is expected by increasing the specific surface area (GSA) of the substrate. This test was designed specifically to stress the cold start performance of the catalyst by using a short, 5 second idle time preceding an aggressive, high exhaust mass flowrate drive cycle.

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.

This paper reports on the desired performances for Catalyzed Soot Filters (Hereinafter referred as “CSF”), which is composed of a Diesel Particulate Filter (DPF) coated with an Oxidation Catalyst, its design factors and their influence on DPF performance, and on the lifetime prediction method to effectively design a DPF for durability. Performance means pressure drop, Particulate Matter (PM) regeneration limit, time for light-off, and canning strength. Design factors include cell structure, overall DPF size and material porosity. Knowing the relationships between performance and design factors assist the engineer in optimizing the selection of material, cell structure and size of the DPF.

Diesel Particulate Filters (DPF) made of cordierite are generally used for diesel engine aftertreatment systems in both on-road and commercial off-highway vehicles to meet today’s worldwide emission regulations. PM/PN and NOx emission regulations will become more stringent worldwide, as represented by CARB2027 and Euro7. Technologies that can meet these strict regulations are required. As a result, aftertreatment systems have become more complex with limited space. Recently, off-highway OEMs have been interested in downsizing the aftertreatment system using concepts such as DOConFilter in an effort to reduce the size of the exhaust system. DOConFilter can effectively replace DOC + CSF or DOC + bare DPF systems with a single zone coated particulate filter. DOConFilter systems have an increased amount of coating compared to CSF as higher-filtration filters will become the norm. An undesirable increase in pressure drop is expected by adopting this new technology.

Diesel Particulate Filters (DPF) are becoming mandatory for many Heavy Duty Vehicle (HDV) and Non Road Mobile Machinery (NRMM) applications as the requirement for particulate filtration performance has increased over this past decade. In a previous study, a new generation of cordierite DPF was developed to meet the latest major emission regulations; PN-PEMS requirement for EuroVI StepE, while maintaining a lower pressure drop and high ash capacity. Despite the improvements made in the latest generation DPF material, the introduction of tighter particulate regulations demands further improvement in DPF technology. More specifically, PN emission limits for Euro7 under wide operation conditions in conjunction with PN down to 10nm, as described in the proposal from Consortium for Ultra Low Vehicle Emission (CLOVE), requires further improvement in PN filtration performance. Pressure drop, which may negatively influence the CO2 emissions, remains a key performance criteria.