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Technical Paper

An Elementary Simulation of Vibration Isolation Characteristics of Hydraulically Damped Rubber Mount of Car Engine

2001-04-30
2001-01-1453
Hydraulically damped rubber engine mounts (HDM) are an effective means of providing sufficient isolation from engine vibration while also providing significant damping to control the rigid body motions of the engine during normal driving conditions. This results in a system which exhibits a high degree of non-linearity in terms of both frequency and amplitude. The numerical simulation of vibration isolation characteristics of HDM is difficult due to the fluid-structure interaction between the main supporting rubber and fluid in chambers, the nonlinear material properties, the large deformation of rubber parts, structure contact problems among the inner parts, and the turbulent flow in the inertia track. In this paper an integrated numerical simulation analysis based on structural FEM and a lumped-parameter model of HDM is carried out.
Technical Paper

Performance and Durability Evaluation of Continuously Regenerating Particulate Filters on Diesel Powered Urban Buses at NY City Transit

2001-03-05
2001-01-0511
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.
Technical Paper

Diesel Emission Control in Review

2001-03-05
2001-01-0184
This paper gives a comprehensive overview of the current state-of-the-art in diesel emission control. The nature of diesel particulates is summarized. The variety of diesel particulate filter regeneration strategies that will become so important to filter application are reviewed. Filter retrofit and durability issues are addressed. DeNOx catalysts, SCR, NOx traps for diesel, and non-thermal plasma methods are summarized. Integrated NOx/PM systems are described. And reduction of exhaust toxics is discussed. The paper covers all major conferences in the year 2000 that occurred in the US and Europe. US and Europe.
Technical Paper

Validation of a Model and Development of a Simulator for Predicting the Pressure Drop of Diesel Particulate Filters

2001-03-05
2001-01-0911
As demand for wall-flow Diesel Particulate Filters (DPF) increases, accurate predictions of DPF behavior, and in particular their pressure drop, under a wide range of operating conditions bears significant engineering applications. In this work, validation of a model and development of a simulator for predicting the pressure drop of clean and particulate-loaded DPFs are presented. The model, based on a previously developed theory, has been validated extensively in this work. The validation range includes utilizing a large matrix of wall-flow filters varying in their size, cell density and wall thickness, each positioned downstream of light or heavy duty Diesel engines; it also covers a wide range of engine operating conditions such as engine load, flow rate, flow temperature and filter soot loading conditions. The validated model was then incorporated into a DPF pressure drop simulator.
Technical Paper

Inertial Contributions to the Pressure Drop of Diesel Particulate Filters

2001-03-05
2001-01-0909
Wall-flow Diesel particulate filters operating at low filtration velocities usually exhibit a linear dependence between the filter pressure drop and the flow rate, conveniently described by a generalized Darcy's law. It is advantageous to minimize filter pressure drop by sizing filters to operate within this linear range. However in practice, since there often exist serious constraints on the available vehicle underfloor space, a vehicle manufacturer is forced to choose an “undersized” filter resulting in high filtration velocities through the filter walls. Since secondary inertial contributions to the pressure drop become significant, Darcy's law can no longer accurately describe the filter pressure drop. In this paper, a systematic investigation of these secondary inertial flow effects is presented.
Technical Paper

Mathematical Modeling of Vehicle Fuel Cell Power System Thermal Management

2003-03-03
2003-01-1146
A mathematical model of vehicle fuel cell system thermal management has been developed to investigate the effects of various design and operating conditions on the thermal management and to understand the underlying mechanism. The fuel cell stack structure is represented by a lumped thermal mass model, which has the heat transfer and pressure loss characteristics of the fuel cell stack structure. The whole thermal management system is discretized into many volumes, where each flowspit is represented by a single volume, and every pipe is divided into one or more volumes. These volumes are connected by boundaries. The model is solved numerically to analyze thermal management system performance. The effects of coolant flow rates and air flow rates on the system thermal performance, the stack thermal capacity on the transient thermal performance have been investigated in detail.
Technical Paper

Low Back Pressure, High Efficiency Automotive Cabin Air Odor Filters

1996-02-01
960943
Preliminary back pressure and adsorption performance results are reported for two activated carbon honeycomb materials. The carbon impregnated honeycomb (CIH) material is porous ceramic honeycomb with a complete impregnation and coating of activated carbon on all ceramic surfaces. It offers the potential to be a permanent odor filter in that it can be in situ electrically regenerated. It has adsorption performance similar to commercially available layered filters, but has much lower back pressure. The second material is an activated carbon honeycomb (ACH) and is not ceramic-based as is CIH. As such, it has much more activated carbon and superior adsorption performance. The back pressure is low, as with CIH. It has significant potential as a high-performing disposable odor filter.
Technical Paper

High Temperature Compressive Strength of Extruded Cordierite Ceramic Substrates

1995-02-01
950787
High temperature modulus of rupture (MOR) data, published previously, show that the ceramic catalyst supports get stronger with temperature due to the absence of water vapor and closure of microcracks which would otherwise act as stress concentrators [1, 2 and 3]*. The increased MOR value is partially responsible for the excellent durability of ceramic catalyst supports at high temperature. In this paper, we will present the compressive strength data of ceramic substrates at high temperature, namely the crush strength along B-axis and biaxial compressive strength of the whole substrate. Since the honeycomb strength is directly related to that of the individual cell wall, the compressive strength should also increase with temperature similar to the modulus of rupture. Accordingly, the ceramic substrates are capable of supporting higher mounting pressures exerted by the intumescent mat at high temperature [4].
Technical Paper

Advances of Durability of Ceramic Converter Systems

1996-10-01
962372
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.
Technical Paper

Study of the Injection Control Valve in a New Electronic Diesel Fuel System

1998-02-23
980813
At first, the dynamic electromagnetic characteristics of a pulsed solenoid valve is analyzed by experiments. The fast valve response is obtained by material modifications. Then, the intelligent solenoid driving method is discussed. The new techniques of the “active” PWM and the “d2i/dt2” detection are developed for feedback control of the solenoid holding current and the valve closure timing. Finally, the control and diagnosis method for the valve closure duration is investigated. A sensing mechanism utilizing momentary camshaft speed fluctuations of fuel injection pump is presented, which provides the basis for feedback control and diagnosis of the valve closure duration and diesel fuel injection process.
Technical Paper

Development of a Diesel Particulate Filter Composition and Its Effect on Thermal Durability and Filtration Performance

1994-03-01
940235
This paper details the development of the EX-80 composition, a new cordierite material for use as a diesel particulate filter (DPF), that was developed based on the following objectives; (1) improved thermal durability, (2) high filtration efficiency and (3) low pressure drop. The achievement of these goals was demonstrated through engine testing, stress modeling, and other evaluations. EX-80 has a low coefficient of thermal expansion (CTE) averaging less than 4x10-7°C-1 (25°C-800°C), the Modulus of Rupture (MOR) averages greater than 350 psi and the Modulus of Elasticity (MOE) averages less than 0.8 x 106 psi. The improvement of these three properties has resulted in improved thermal durability for EX-80 as compared to the current Corning DPF compositions (EX-47, EX-54 and EX-66). The new cordierite composition has been designed to achieve a low pressure drop as a function of soot loading (0.30 inHg/gm of soot collected), coupled with high efficiency, averaging greater than 90%.
Technical Paper

Optimization of Extruded Electrically Heated Catalysts

1994-03-01
940468
Low mass extruded electrically heated catalysts (EHC) followed directly by light-off and main converters resulted in non-methane hydrocarbon emissions (NMHC) between .020 and .023 g/mi at power levels as low as 1 kw and energy levels as low as 4 whr. These results were achieved on a 1993, 2.2 liter vehicle. The success of this system is due to rapid heat up of the catalyzed surface areas of both the heater and light-off converter. The energy added to the exhaust from both the heater and the light-off is then efficiently transferred to the main converter. In addition, the impact of power and energy on NMHC levels was determined. The Ultra-Low Emissions Vehicle (ULEV) standard was also achieved with uncatalyzed heaters and on a 1990, 3.8 L vehicle. The new California Low Emission Vehicle (LEV) and Ultra Low Emission Vehicle (ULEV) standards require a significant reduction in tail pipe emissions compared to current standards.
Technical Paper

High Temperature Durability of Electrically Heated Extruded Metal Support

1994-03-01
940782
The design, performance and optimization of the extruded electrically heated metal converter have recently been published(1,2). The present paper focuses on the physical durability of extruded metal EHC support at high temperature representative of operating conditions. The mechanical, thermal, creep and fatigue properties of Fe-Cr-Al honeycomb structure over 25°-1000°C temperature range are reported. In addition, the stresses arising from mounting and thermal loads are computed via finite element analysis and compared with the high temperature strength of extruded metal EHC support. A safe design stress which predicts 192,000 kilometer durability is estimated from high temperature fatigue behavior of extruded Fe-Cr-Al honeycomb structure.
Technical Paper

Design Considerations for a Ceramic Preconverter System

1994-03-01
940744
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.
Technical Paper

Systems Design for Ceramic LFA Substrates for Diesel/Natural Gas Flow- Through Catalysts

1995-02-01
950150
The monolithic, large frontal area (LFA), extruded ceramic substrates for diesel flow-through catalysts offer unique advantages of design versatility, longterm durability, ease of packaging and low Cost [1, 2]*. This paper examines the effect of cell density and cell size on catalyst light-off performance, back pressure, mechanical and thermal durability, and the steady-state catalytic activity. The factors which affect these performance characteristics are discussed. Certain trade-offs in performance parameters, which are necessary for optimum systems design, are also discussed. Following a brief discussion of design methodology, substrate selection, substrate/washcoat interaction and packaging specifications, the durability data for ceramic flow-through catalysts are summarized. A total of over 18 million vehicle miles have been successfully demonstrated by ceramic LFA catalysts using the systems design approach.
Technical Paper

Fatigue and Performance Data for Advanced Thin Wall Ceramic Catalysts

1998-02-23
980670
With stricter emissions standards, low back pressure requirements, and 100,000 mile durability specifications, ceramic catalysts have undergone significant developments over the past few years. The thrust in the ceramics area has centered on thin-wall structures to minimize back pressure and on high cell density for rapid light-off in close-coupled applications. The thin-wall structures are extruded from low expansion cordierite ceramic with adequate strength and thermal shock resistance equivalent to those of standard cordierite substrate. Examples of thin-wall substrate include 350XT which is extruded from a very low expansion dense cordierite ceramic, and 400/4 and 600/4 cell structures extruded from a low expansion modified cordierite ceramic. This paper will focus on the high fatigue resistance, excellent conversion efficiency, and low back pressure of 350 XT substrates with advanced washcoat system.
Technical Paper

The Design of Automotive Catalyst Supports for Improved Pressure Drop and Conversion Efficiency

1991-02-01
910371
The current automotive catalytic converter is highly dependable and provides excellent emissions reduction while at the same time it offers little resistance to the flow of gasses through the exhaust system. As automobile performance requirements increase, and as the allowable tailpipe emissions are tightened, there is a need on the one hand to reduce the back pressure even further, and on the other, to increase the already excellent catalytic performance. This paper will analyze the substrate factors which influence the pressure drop and conversion efficiency of the catalyst system. The converter frontal area has the most significant influence on both pressure drop and conversion efficiency, followed in order by part length, cell density, and wall thickness.
Technical Paper

Durable Packaging Design for Cordierite Ceramic Catalysts for Motorcycle Application

1993-03-01
930161
The motorcycle emissions regulations for both two-stroke and four-stroke engines, which are receiving worldwide attention, will go into effect in the very near future. To meet these regulations, the motorcycles will require a catalyst in conjunction with the muffler due to space limitations. The combination of high engine speeds, high vibrational acceleration, high HC and CO emissions, high oxidation exotherms, and stringent durability requirements, points to cordierite ceramic substrate as an ideal catalyst support. However, as an integral unit within the muffler, its packaging design must be capable of withstanding isothermal operating conditions which may exceed the upper intumescent temperature limit of the ceramic mat. This paper describes a durable packaging design for the ceramic catalyst which employs a hybrid ceramic mat, special end rings and gaskets, and high strength stainless steel can.
Technical Paper

Size Effect on the Strength of Ceramic Catalyst Supports

1992-10-01
922333
The typical ceramic catalyst support for automotive application has a total volume of 1640 cm3. Approximately 10% of this volume is subjected to tensile thermal stresses due to a radial temperature gradient in service [1]*. These stresses are kept below 50% of the substrate strength to minimize fatigue degradation and to ensure long-term durability [2]. However, the tensile strength measurements are carried out in 4-point bending using 2.5 cm wide x 1.2 cm thick x 10 cm long modulus of rupture bars in which the specimen volume subjected to tensile stress is merely 3.2 cm3 or 0.2% of the total substrate volume [3]. Thus, a large specimen population is often necessary (50 specimens or more) to obtain the strength distribution representative of full substrate. This is particularly true for large frontal area substrates for diesel catalyst supports with an order of magnitude larger stressed volume. In this paper, the modulus of rupture data are obtained as function of specimen size.
Technical Paper

Measurement of Biaxial Compressive Strength of Cordierite Ceramic Honeycombs

1993-03-01
930165
The stringent durability requirements approaching 100,000 vehicle miles for automotive substrates and 290,000 vehicle miles for large frontal area diesel substrates for 1994+ model year vehicles call for advanced packaging designs with thick ceramic mats and high mount densities. The latter result in high mounting pressure on the substrate and enhance its mechanical integrity against engine vibrations, road shocks and back pressure forces. A novel measurement technique which applies a uniform biaxial compressive load on the lateral surface of ceramic substrates, thereby simulating canning loads, is described. The biaxial compressive strength data obtained in this manner help determine the maximum mounting pressure and mat density for a durable packaging design. The biaxial compressive strength data for both round and non round substrates with small and large frontal area are presented.
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