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With more stringent CO2 emission regulation in the world, Plug-in Hybrid Electric Vehicle (PHEV, also known as off-vehicle charging hybrid electric vehicle, OVC-HEV) plays a more important role in the current modern market, such as in China. At the same time, Real Driving Emission (RDE) was introduced in both Euro 6d and China 6b regulation, which covers more factors in the real driving practice including altitude, environment temperature, fuel quality, driving behaviors, and so on, which could potentially impact the pollutant emissions. Besides above mentioned, for PHEV, the state of charge (SOC) of the battery is also considered as one important factor, which could impact the engine load and emissions.

Gasoline particulate filters (GPF) have become a standard aftertreatment component in Europe, China, and since recently, India, where particulate emissions are based on a particle number (PN) standard. The anticipated evolution of regulations in these regions towards future EU7, CN7, and BS7 standards further enhances the needs with respect to the filtration capabilities of the GPFs used. Emission performance has to be met over a broader range in particle size, counting particles down to 10nm, and over a broader range of boundary conditions. The requirements with respect to pressure drop, aiming for as low as possible, and durability remain similar or are also enhanced further. To address these future needs new filter technologies have been developed. New technologies for uncatalyzed GPF applications have been introduced in our previous publications.

The gasoline particulate filter (GPF) represents a practical solution for particulate emissions control in light-duty gasoline-fueled vehicles. It is also seen as an essential technology in North America to meet the upcoming US EPA tailpipe emission regulation, as proposed in the “Multi-pollutant Rule for Model Year 2027”. The goal of this study was to introduce advanced, uncoated GPF products and measure their particulate mass (PM) reduction performance within the existing US EPA FTP vehicle testing procedures, as detailed in Code of Federal Regulations (CFR) part 1066. Various state-of-the-art GPF products were characterized for their microstructure properties with lab-bench checks for pressure drop and filtration efficiency, then pre-conditioned with an EPA-recommended 1500 mile on-road break-in, and finally were tested on an AWD vehicle chassis-dyno emissions test cell at both 25°C and -7°C ambient conditions.

As the official proposal for emission regulation Euro 7 has been released by European Commission, PN above 10nm is taken into consideration for the ultrafine particulate emissions control. The challenges of GPF filtration efficiency emerge for the light-duty manufactures to meet the future emission standards. In the present study, a China 6 compliant vehicle was tested to reveal its performance over the China 6 standards and potential to meet the upcoming Euro 7. Three GPF product types (Gen 1, Gen 2, and concept Gen 3) were mounted to the tested vehicle. WLTC tests were conducted on chassis dynamometer in laboratory as well as a self-designed aggressive cycle (“Base Cycle”) tests. To explore the GPFs performance for PN emissions above 10nm against the proposed limit 6.0E11 #/km, PN emission above 10nm were measured in our laboratory tests for both engine out and tailpipe as well as the PN emission above 23nm.

As in the past several years, we provide here an overview of recent major regulatory and technological changes for reducing emissions from the transport and off-road sector. In the past, this review was focused mostly on improvement in engine efficiency and tailpipe emissions of criteria pollutants. However, starting last year [1] we have increased the scope to broadly address the increased focus on greenhouse gas emissions and the emergence of various non-conventional fuel pathways to achieve the various decarbonization goals. There are two broad themes that are emerging, and which we describe here. Firstly, that we are approaching the implementation of the last of the major regulations on criteria pollutant emissions from cars and trucks, led by Europe, through Euro 7 standards and US, through multi-pollutant standards for light- and heavy-duty vehicles.

RDE test has been introduced to the light-duty vehicle certification process in both China 6 and Euro 6d standards. The RDE test shall be performed on-road with PEMS, which is developed to complement the current laboratory certification of vehicles and ensure cars to deliver low emissions under more realistic on-road driving conditions. Particulate matter has been highly perceived as a significant contributor to human health risks and thus strictly regulated globally. For the RDE evaluation, the MAW method used by the China 6 standard is usually found less stringent than the RMA method used by the Euro 6d standard. In the present study, both of the MAW and RMA methods were applied to different driving cycles and operating conditions, which met the general RDE test requirements, yet resulted in different evaluated PN results.

This review covers advances in regulations and technologies in the past year in the field of vehicular emissions. We cover major developments towards reducing criteria pollutants and greenhouse gas emissions from both light- and heavy-duty vehicles and off-road machinery. To suggest that the transportation is transforming rapidly is an understatement, and many changes have happened already since our review last year [1]. Notably, the US and Europe revised the CO2 standards for light-duty vehicles and electrification mandates were introduced in various regions of the world. These have accelerated plans to introduce electrified powertrains, which include hybrids and pure electric vehicles. However, a full transformation to electric vehicles and the required grid decarbonization will take time, and policy makers are accordingly also tightening criteria pollutant standards for internal combustion engines.

Examination of field-fractured windshields was conducted for purposes of determining the principle fracture mechanisms experienced in-use. Samples for the study were gathered both in the United States (New York) and in Europe (France) to explore whether the primary causes of failure were similar for the different geographic regions. In total, over two hundred individual field-fractures were obtained and examined for the study. Detailed fracture analysis of the parts was performed, and multiple fracture mechanisms were identified and quantified. It was found that the two most frequently observed failure modes were common for both regions with the most frequent cause (~70%) of fractures being due to sharp contact of the exterior ply, while Hertzian cone cracking of the outer ply was the second leading cause (~20%). Several other modes were also identified. Given that sharp impact fracture was the dominant observed failure mode, a high-speed, sharp impact test method was developed.

Gasoline particulate filter (GPF) is considered a suitable solution to meet the increasingly stringent particle number (PN) regulations for both gasoline direct injection (GDI) and multi-port fuel injection (MPI) engines. Generally, GDI engines emit more particulate matter (PM) and PN. In recent years, GDI engines have gained significant market penetration in the automobile industry owing to better fuel economy and drivability. In this study, an accelerated ash loading method was tested by doping lubricating oil into the fuel for a GDI engine. Emission tests were performed at different ash loads with different driving cycles and GPF combinations. The results showed that the GPF could significantly reduce particle emissions to meet the China 6 regulation. With further ash loading, the filtration efficiency increased above 99% and the effects on fuel consumption and backpressure were found to be limited, even with an ash loading of up to 50 g/l.

The automotive industry continues to develop technologies for reducing vehicle fuel consumption. Specifically, vehicle lightweighting is expected to be a key enabler for achieving fleet CO2 reduction targets for 2025 and beyond. Hybrid glass laminates that incorporate fusion draw and ion exchange innovations are thinner and thereby, offer more than 30% weight reduction compared to conventional automotive laminates. These lightweight hybrid laminates provide additional benefits, including improved toughness and superior optics. However, glazing weight reduction leads to an increase in transmission of sound through the laminates for certain frequencies. This paper documents a study that uses a systematic test-based approach to understand the sensitivity of interior vehicle noise behavior to changes in acoustic attenuation driven by installation of lightweight glass.

The use of lightweight materials to produce automotive glazing is being pursued by vehicle manufacturers in an effort to improve fuel economy. As glazing’s become thinner, reduced rigidity means that the critical flaw size needed to create fracture becomes much smaller due to increased strain under load or impact. This paper documents experiments focused on the impact performance of several alternative thin laminate constructions under consideration for windshield applications (including conventional annealed soda-lime glass as well as laminates utilizing chemically strengthened glass), for the purpose of identifying new and unique failure modes that result from thickness reduction. Regulatory impact tests and experiments that focused on functional performance of laminates were conducted. Given the increased sensitivity to flaw size for thin laminates, controlled surface damage was introduced to parts prior to conducting the functional performance tests.

Regulations that limit emissions of pollutants from gasoline-powered cars and trucks continue to tighten. More than 75% of emissions through an FTP-75 regulatory test are released in the first few seconds after cold-start. A factor that controls the time to catalytic light-off is the heat capacity of the catalytic converter substrate. Historically, substrates with thinner walls and lower heat capacity have been developed to improve cold-start performance. Another approach is to increase porosity of the substrate. A new material and process technology has been developed to significantly raise the porosity of thin wall substrates (2-3 mil) from 27-35% to 55% while maintaining strength. The heat capacity of the material is 30-38% lower than existing substrates. The reduction in substrate heat capacity enables faster thermal response and lower tailpipe emissions. The reliance on costly precious metals in the washcoat is demonstrated to be lessened.

This paper compares the emissions performance of four ultra thin wall ceramic substrates with standard wall thickness product on a chassis dynamometer for two different substrate volumes. This comparison helps establish performance trends and provides useful information for selection of substrates in designing catalytic converter systems. This experimental study tests and compares four ultra thin wall products (400/4, 600/3, 600/4, and 900/2) with a standard wall product (400/6.5) at two different substrate volumes. Engine bench aging is used to simulate typical aged conditions. Temperature data as well as second by second and bag emissions data for hydrocarbons, carbon monoxide and oxides of nitrogen were used to evaluate the relative performances of the substrates. The US FTP and US06 driving cycles were used as protocols for the comparison. Results suggest that lower bulk density and higher geometric surface area interact to lead to lower emissions.

In urban areas, particulate emission from diesel engines is one of the pollutants of most concern. As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US. A project entitled, “Clean Diesel Vehicle Air Quality Project” has been initiated by NY City Transit under the supervision of NYSDEC and with active participation from several industry partners. Under this program, 25 NY City transit buses with DDC Series 50 engines have been equipped with continuously regenerating diesel particulate filter systems and have been operating with ultra low sulfur diesel (< 30 ppm S) in transit service in Manhattan since February 2000. These buses were evaluated over a 9 month period for operations, maintainability and durability of the particulate filter.

Mat material durability data in the form of fragility curves were generated in a critical temperature region for three intumescent mat materials considered for low temperature converter applications. The mat materials were tested in a tourniquet wrap converter configuration employing a cylindrical ceramic substrate. Prior to developing durability data for these mat materials, the test items were subjected to various environmental thermal and/or vibration aging conditions. Mat material fragility data were generated in terms of the dynamic force required to impose prescribed differential motion between the can and substrate, thereby, subjecting the mat material to a dynamic shearing like that expected during resonant excitation. As expected, it was found that the mat material capacity to resist shearing deformation decreased when the test samples were subjected to 36 hours of low temperature thermal cyclic aging.

Particulate emission from diesel engines is one of the most important pollutants in urban areas. As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US. A project entitled “Clean Diesel Demonstration Program” has been initiated by NY City Transit under the supervision of NY State DEC and with active participation from several industrial partners. Under this program, several NY City transit buses with DDC Series 50 engines have been equipped with continuously regenerating diesel particulate filter system and are operating with ultra low sulfur diesel (< 30 ppm S) in transit service in Manhattan since February 2000. These buses are being evaluated over a 8-9 month period for operations, maintainability and durability of the particulate filter.

To aid in the catalytic converter design and development process, a test apparatus was designed and built which will allow comparative evaluation of the durability of candidate mat materials under highly controlled thermal and vibration environments. The apparatus directly controls relative shear deflection between the substrate and can to impose known levels of mat material strain while recording the transmitted shear force across the mat material. Substrate and can temperatures are controlled at constant levels using a resistive thermal exposure (RTE) technique. Mat material fatigue after several million cycles is evident by a substantial decrease in the transmitted force. A fragility test was found to be an excellent method to quickly compare candidate materials to be used for a specific application. Examples of test results from several materials are given to show the utility of the mat material evaluation technique.

Governing bodies world-wide are setting increasingly tighter emission standards to help improve air quality. US and Californian LEV/ULEV standards are pace setting, European Stage II legislation has just become effective. In Brazil, the upcoming 1997 standards are also demanding for tighter emission control. The monolithic ceramic honeycomb catalytic converter -for more than the past 20 years- has been a reliable key element in the automotive emission control systems. In order to help meet tightened emission regulation as well to satisfy even more stringent durability requirement, an advanced thinwall ceramic Celcor XT has been developed for increased geometric surface area and reduced backpressure. The product properties as well as FTP and ECE emission and durability test results are being described in this paper. Converter system durability is also determined by robust canning and mounting systems. A durable mounting concept, especially for preconverters, is being described.

Extruded metal honeycombs are used as electrically heated catalysts (EHCs). The durability requirements of this application make demands on high surface area, thin cross-section metal honeycombs. Significant durability improvements over previous extruded metal honeycomb EHCs have been achieved by material and package design changes. The product redesign was supported by finite element models and extensive testing. The redesigned EHC has passed severe laboratory and field testing. The tests include electrical cycling to 1000°C/1600 cycles, hot vibration to 60g/900°C and demanding on-vehicle exposure. Excellent durability of the extruded metal honeycomb has been demonstrated.

The preconverter is an essential element of exhaust gas treatment to help meet the tighter emission standards of TLEV and LEV levels. Its design must be chosen so as to meet the simultaneous requirements of compactness, faster light-off, low back pressure, high temperature durability and low cost. This paper presents design options for a ceramic substrate and durable package which lead to an optimum and cost-effective preconverter system. Preliminary data for high temperature physical durability of selected converter systems are presented. Performance parameters for light-off activity and back pressure are also computed and compared with those of standard substrates used in underbody application. Laboratory tests comprising of axial push-out test, high temperature vibration test, exhaust gas simulation test and the engine dynamometer test demonstrate the viability of ceramic preconverters for automotive application.