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The paper presents a 2-dimensional model for the calculation of the regeneration process in a wall flow diesel particulate filter. The model includes heat transfer by conduction and convection, a model for particle combustion based on diffusive burning of individual particles, and flow through the channels and across the filter walls. It was found that only the pressure drop across the walls need be considered for normal regeneration conditions. Comparisons between model predictions and experimental results for spatial dependent temperature time histories, and integrated degree of regeneration are used to validate the model. The validations were carried out for a series of severe regenerations, where there are large changes in flow and temperature throughout the process. Relative magnitudes of energy flows due to combustion, convection, and conduction are presented, as well as parametric studies of the effects of temperature, oxygen concentration and soot loading.

In the last years the development of diesel particulate traps and trap regeneration systems has led to some very promising concepts. In parallel the development of diesel engine technology for passenger cars, as well as for light and heavy duty vehicles, has resulted in remarkable improvements especially regarding particulate and NOx emissions, engine performance and fuel economy. Unfortunately, for some aspects the development and application of particulate trap systems on the one hand and diesel engine technology on the other have led to conflicting solutions. For example, exhaust gas temperatures of at least 500 °C to 600 °C are necessary to burn off the soot that has been emitted by the engine and collected in a particulate trap. However, the increased fuel efficiency of modern TDI diesel engines and the trend to reduced average traffic speed very often cause exhaust temperatures below 200 °C at urban driving conditions.

A ceria stabilised zirconia supported Pd/Zn catalyst (Pd/Zn ratio=1:2) has demonstrated its ability to perform as a three-way catalyst (TWC) and to give conversions of up to 99% of a stoichiometric mixture of carbon monoxide/npropane/nitric oxide/dioxygen in dinitrogen carrier at a WHSV of 44,000 h-1. The catalyst also exhibits excellent thermal stability inoxidising conditions. Characterisation of the catalyst has been performed using XRD, XPS, BET,and DSC. From this it has emerged that the palladium is in a highly dispersed state, closely associated with the zinc phase. In situ kinetic studies have also been conducted under continuous flow conditions.

Diesel engines are coming under stricter requirements to reduce emissions. particularly those of particulates and nitrogen oxides (NOx). Recently, the U. S. EPA put into place staged requirements for heavy duty diesel engines in urban bus applications which are aimed at ultimately bringing pre-1994 engines into particulate emissions compliance with 1994 heavy duty on-road truck standards (0. 1 g/bhp-hr TPM). This reflects the need to control emissions in crowded urban environments. Zirconia based ceramic combustion management coatings, although originally developed for adiabatic or low heat rejection engines to boost thermal efficiency, have also been shown to contribute to the reduction in diesel emissions. Heavy duty transient testing of rebuilt 2-stroke MUI diesel bus engines equipped with stabilized zirconia based coatings applied by thermal spray process have shown significant reduction in exhaust opacity relative to a baseline, uncoated engine.

Three-way conversion (TWC) catalyst supports were prepared having CeO2-ZrO2 solid solution particles uniformly dispersed on γ-Al2O3 as discrete crystallites. The support morphology was characterized using STEM and TEM analysis. TPR and XRD analyses were also carried out on precious metal (PM) containing and PM-free samples before and after aging. These studies were combined with performance measurements which demonstrated the beneficial effects of solid solution formation on TWC catalyst activity. STEM and TEM analysis showed that well-dispersed CeO2-ZrO2 solid solution particles could be formed and simultaneously supported on a high surface area γ-Al2O3 support. For samples calcined up to 600°C, crystallite sizes of ≤50Å were formed as compared to sizes of over 200Å in the aged samples. The TPR studies suggested that for supports calcined up to 600°C most of the CeO2 present was reduced from the Ce4+ to the Ce3+ state in the temperature range 250 - 700°C.

Current major concerns m auto exhaust three-way conversion (TWC) catalyst are: 1) improved thermal stability for high temperature applications, such as low emission vehicles (LEV), and 2) high O2 storage capacity for on-board diagnostic (OBD) systems to meet OBD-2 regulations. These are challenges to catalyst technologies posed by the regulations. Of the many possible approaches, stabilization of Rh and CeO2 by ZrO2 shows promise in TWC formulations. This paper summarizes our investigations of thermally stabilized Zr containing TWC catalysts, including the chemistry of CeO2 stabilization with ZrO2, and their OBD-2 characteristics.

Zirconium dioxide (zirconia) is a well-known material often being a major component in the washcoat systems of three-way catalysts (TWC) and diesel oxidation catalysts. One important characteristic of zirconia containing washcoats is an improved aging stability which is required to meet the more and more stringent emission standards. In the last few years the utilization of zirconia became even more important - especially for high sophisticated three-way washcoat systems. This was due to the development of high temperature stable oxygen storage components, containing cerium dioxide (ceria) in combination with different other oxides - one very promising candidate being zirconia. In the present work the results of a research program are discussed, focusing on the influence of zirconia in combination with ceria and additional rare earth promoters on the stability of the oxygen storage characteristics.

Vibration and noise are generally considered to be the major problems in power transmission chains. This paper presents an adaptive, active control strategy for the reduction of vibration in automotive timing chain drives and examines the effects of the active control on noise reduction. Experimental results show that the average vibration amplitude is diminished by as much as 90% under low to moderate tension conditions, and the chain noise is reduced by about 3 dB. The experimental apparatus has low cost and is readily applicable to an industrial environment.

Compression in the head-neck complex often causes fractures of the first cervical vertebra (C1). The type of fracture often determines whether the injury is stable or unstable, which significantly affects the ultimate injury severity. The often unstable bursting fracture of C1 is thought to be caused by a transformation of axial compressive forces into lateral bursting forces by the wedge-shaped lateral masses. The purpose of this study was to measure the orientation of the joint surfaces of C1 to determine whether this symmetry exists. An additional goal was to determine whether the orientation of the joint surfaces varied significantly with location on the surface. Direct measurements of surface coordinates were taken from 40 dried vertebrae. The angles of two areas on each of the four joint surfaces of the lateral masses of C1 were then calculated. The resulting angles agreed with previous investigations of upper cervical vertebral anatomy.

In a review of 540 crashes in which the steering-wheel airbag deployed, 38% of the drivers sustained some level of upper extremity injury. The majority of these were AIS-1 injuries including abrasions, contusions and small lacerations. In 18 crashes the drivers sustained AIS-2 or-3 level upper extremity injuries, including fractures of the radius and/or ulna, or of the metacarpal bones, all related to airbag deployments. It was determined that six drivers sustained the fracture(s) directly from the deploying airbag or the airbag module cover. The remaining 12 drivers had fractures from the extremity being flung into interior vehicle structures, usually the instrument panel. Most drivers were taller than 170 cm and, of the 18 drivers, 10 were males.

Automobile insurance claims of two popular midsize cars with different air bag deployment frequencies -- the Dodge/Plymouth Neon and Honda Civic -- were examined to determine performance in higher severity crashes (the upper 30 percent of crashes ranked by adjusted repair cost). Previously, it was found that drivers sustained more, mainly minor, injuries in the Neon which had a higher deployment frequency in low speed crashes. This study examined, for these two cars, whether there was any trade-off associated with a higher deployment threshold. It was found that even at higher speeds, the Neon had a greater frequency of air bag deployments, which in turn resulted in a greater likelihood of driver injury. Once again upper extremity injuries were most prevalent for Neon drivers and were highest for female drivers. At the same time, there was little evidence that driver protection was compromised in the Civic in the more important high speed crashes.

This paper reviews the literature regarding injuries and fatalities in frontal accidents in vehicles equipped with air bag systems. An analysis is presented of the nature of fatal injuries attributable to airbag deployment, which accounts for the age, sex, and accident modality. Injury analysis is reviewed in the same fashion. Airbag-induced injuries appear to relate to the proximity of the motorist to the unit when it inflates. Suggestions have been made to modify seat belt systems, the ergonomics of the driver's position and the design of the airbag units to minimize deployment injury.

The body or chassis of the modern motor vehicle is still fundamentally and commonly designed on the horse and cart concept. This solid chassis, upon which the cart was built, offers little or no crushing zone effect in the event the motor vehicle and its occupants are subject to an impact due to a collision. Although we see an array of modern motor vehicle safety devices, injury and fatalities are still appearing at an alarming rate, some directly due to these safety devices. This paper attempts to present a synergistic approach to motor vehicle safety. One of the most important safety features that has been overlooked by most automobile manufacturers is a uniform crushing zone on bumper areas. It appears at present and possibly in the future that crushing zones on bumper areas have been and will be neglected. Thus a fundamental safety principle that could be used to prevent injury and fatalities in automobile accidents will be neglected.

A new front bumper, blow molded from an engineering thermoplastic, is being used to provide full 8 km/h federal pendulum and flat-barrier impact protection, as well as angled barrier protection on a small passenger car. The low intrusion bumper is compatible with the vehicle's single-sensor airbag system and offers a 5.8 kg mass savings compared with competitive steel/foam systems. This paper will describe the design and development of the bumper system and the results achieved during testing.

The stiffness of randomly oriented, thermoplastic bulk molding compound (TP-BMC) composites can be increased in a 3-point loading test through the use of commingled thermoplastic materials. Bumper beams for a typical midsize vehicle produced from combinations of these 2 materials were molded and tested using a static bumper test setup that measures the applied load and resulting deflection. A design of experiments investigation based on the Taguchi methods [1] were used to compare the effects of 4 material and processing variables on static load. The optimum levels for each variable were found to achieve maximum load at 25 mm deflection, which led to a manufacturing strategy for selectively increasing the stiffness of TP-BMC composites for bumper beams. This paper details the development work.

The stiffness of randomly oriented, glass-mat thermoplastic (GMT) composites with a polypropylene matrix can be increased in a 3-point loading test through the selective use of a co-mingled E-glass and polypropylene filament thermoplastic prepreg. Bumper beams for a typical midsize vehicle made from combinations of these 2 materials were molded and tested using a static bumper test setup, with load being measured as a function of deflection. A design of experiments investigation based on the Taguchi methods [1, 2] was used to compare the effects of 4 glass-mat orientation variables on the measured static load response of the molded bumper beams. This led to follow-up tests of materials and design strategies for selectively increasing the stiffness of the GMT composites at select locations in the bumper beam. The details of the investigation and results will be discussed in this paper.

A conceptual step-pad bumper system has been designed for a sport utility vehicle. This bumper incorporates an all-thermoplastic solitary beam/fascia with a Class A finish and a replaceable, grained thermoplastic olefin (TPO) or urethane step pad. The rear beam is injection molded and the cover plate features integrated through-towing capabilities and electrical connections. The bumper is designed to pass FMVSS Part 581, 8 km/h impacts. The system can potentially offer a 5.0-13.6 kg weight savings at comparable costs to conventional step-pad bumper systems. This paper will detail the design and development of the concept and finite-element analysis (FEA) validation.

The instrument panel (IP) is one of the largest, most complex, and visible components of the vehicle interior, and like most other major systems in passenger cars and light trucks, it has undergone considerable aesthetic and functional changes over the past decade. This is because a number of design, engineering, and manufacturing trends have been driving modifications in both the role of these systems and the materials used to construct them since the mid- '80s. This paper will trace the recent evolution of IP systems in terms of the trends affecting both design and materials usage. Specific commercial examples will be used to illustrate these changes.

One of the methods used to mechanically fasten a component such as a radio, cluster or finish panel to a plastic instrument panel substrate involves driving a screw through a metal push-nut which has been inserted into an opening in the plastic instrument panel substrate. A primary failure mode which has been observed for this type of joint is cracking of the plastic substrate surrounding the metal push-nut. Finite Element Analysis (FEA) has been employed to optimize the design of the push-nut opening in a polycarbonate substrate and minimize the potential for cracking of the plastic. For the FEA, the implicit version of the ABAQUS program was used. It was determined that the induced stress in the plastic instrument panel substrate from the fastening process can be minimized by controlling the dimensions of the push-nut opening such that push-nut recess is minimized and the thickness of the substrate in the region whether the push-nut engages is optimized.

The instrument panel is one of the most difficult components of the automobile to recycle. It is difficult to remove and contains a variety of different plastic materials. Through improved design and coordination, the instrument panel may be made more recyclable and environmentally friendly. The proper selection of materials to minimize material count and maximize separability is critical. Proper selection of assembly and disassembly techniques is also needed.