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A detailed description of flow rate measurement technique for automotive exhaust is presented. The system consists of a sector field mass spectrometer for continuous analysis of helium concentration in the exhaust gas and a mass flow controller which injects pure helium at a constant rate into the intake manifold of an engine. The exhaust flow rate can be calculated by helium injection flow rate dividing by the concentration since the concentration value is a measure of the ratio of helium dilution taking place in the engine. The advantages of the technique consist of (1) no disturbance from strong pulsed flow present when an engine is idling, (2) easy time alignment with gas analyzers, and (3) measurement of dry based flow rate that can be directly multiplied by dry based gas concentration to obtain mass emission rate.

This paper presents the vibration control of a thin plate by multiple piezoelectric actuators and sensors which are co-located. To use piezoelectric materials efficiently, the Linear Quadratic Gaussian (LQG) controller is designed on the basis of a Multi-Input Multi-Output system so that each sensor monitors all the modes to be controlled and each actuator excites all the modes to be controlled. The robust LQG controller is then applied for attenuating vibration of a plate that is clamped along its edges and disturbed by a band-limited pseudo-random noise. This controller uses two sensor signal filters in order to control the first three natural modes of the plates. The results of the experiment show that the vibration of controlled modes are attenuated by 10 to 20 dB without destabilizing the other modes.

In the preceding paper the specific heat capacity, substrate heat capacity, and energy requirements of two types of substrates were discussed in detail both from the standpoint of predictions from measured material property values as well as actual energy measurements on ceramic and metal products. This information is valuable for the catalyst designer because of the light-off impact of this energy requirement. Some material was also presented regarding the change in this energy requirement with washcoat loading. Other aspects of the substrate which could reasonably come into play to enhance the light-off characteristics of a catalyst are the rates of heat and mass transfer. The latter of these could reasonably be expected to drive the catalyst activity. In addition, the pressure drop which results from the substrate structure could influence and limit the choice of cell configurations and product shapes and sizes, thereby constraining the list of possible options.

Reducing light-off time by using low thermal mass preconverters and increasing catalyst conversion efficiencies is one way of reducing cold start emissions and attaining mandated emission standards. Additionally, it is desirable to attain these features in a small, flexible package helping to overcome close coupling design constraints. Such a preconverter with an atypical Microlith™ metal catalyst substrate geometry and capable of withstanding high operating temperatures using a proprietary catalyst coating technique was tested with a conventional downstream ceramic main brick. This paper explains the physical characteristics and the flow dynamics of this substrate. Development and testing of prototypes were done on a bench scale apparatus and in automobiles. Bench scale catalyst performance and automotive FTP data before and after aging are presented. Automotive tests were done with and without secondary air and with calibrated Air/Fuel bias.

A theoretical and experimental study of three-dimensional steady and unsteady compressible non-reacting flow inside double flow of monolith catalytic converter system attatched to 6-cylinder engine with two Y type junctions at inlet exhaust pipes was performed for the achievement of performance improvements, reduction of light-off time, and longer service life by improving the flow distribution of pulsating exhaust gases. To obtain the boundary conditions to CFD analysis, one dimensional non-steady gas dynamic calculation was also performed by using the method of characteristics in intake and exhaust system. Studies indicate that unsteady representation is necessary because pulsation of gas velocity may affect gas flow uniformity in the monolith. Also simulation results show that the level of flow maldistribution in the monolith heavily depends on curvature and angle of separation streamline of mixing pipe which homogenise the exhaust gas from individual cylinders.

The recent progress of electronic control systems in vehicles is remarkable as evidenced by the development of electronic fuel injection systems,(EFI), automatic transmission control systems, and anti-lock brake systems,(ABS). The number of actuators for the systems has been increasing. Consequently, a need has been identified for a reduction in volume and number of the system actuators for control purposes. A composite magnetic material has been developed with the aim of miniaturizing magnetic solenoid valves for actuator applications. A composite magnetic material is such that both ferromagnetic and paramagnetic sections coexist within a single material, and can contribute to optimization of the magnetic circuit of a solenoid valve. This paper describes the development of a composite magnetic material, and its resultant characteristics.

The wear patterns of the rings and grooves of a diesel engine were analyzed by using a ring dynamics/gas flow model and a ring-pack oil film thickness model. The analysis focused primarily on the contact pressure distribution on the ring sides and grooves as well as on the contact location on the ring running surfaces. Analysis was performed for both new and worn ring/groove profiles. Calculated results are consistent with the measured wear patterns. The effects of groove tilt and static twist on the development of wear patterns on the ring sides, grooves, and ring running surfaces were studied. Ring flutter was observed from the calculation and its effect on oil transport was discussed. Up-scraping of the top ring was studied by considering ring dynamic twist and piston tilt. This work shows that the models used have potential for providing practical guidance to optimizing the ring pack and ring grooves to control wear and reduce oil consumption.

Manufacturers of automotive catalytic converters are constrained to design more effective and reliable systems to meet the stringent emission limits anticipated for the end of the decade. Reactor models and computer simulations may offer new possibilities for optimal catalytic converter design. For this reason, transient models have been developed using the commercial CFD (Computer Fluid Dynamics) code PHOENICS. In this work the effects of catalyst design parameters are studied using the one-dimensional transient model for a single catalyst channel. The results indicate that the catalyst precious metal loading has a great influence on the catalyst light-off, and the geometric area (catalyst length and cell density) and the hydraulic radius (catalyst cell density) on the steady state conversion efficiency. The ceramic catalyst seems to have a higher tendency towards thermal shock than the metallic.

VPT (Variable Piston Timing) utilizes a lightweight piston design that varies the piston displacements and the periods of the 4 strokes, produces a power stroke in every revolution, and more. VPT can incorporate electronic devices by on board computer to change the stroke ratios and the timing during engine operation. This article discusses VPT retrofit of a slow speed engine without electronics. Substantial horsepower, torque and some efficiency gains are achieved. The hardware changes are kept to a minimum. The first engine is scheduled to be tested in the third quarter of 1997. Electronic VPT will be included in the next generation engine.

In this paper, a numerical model is used to study the influence of several relevant parameters on the behaviour of a turbocharged Diesel engine as an exhaust noise source, with two main objectives: first, determine if it is possible to reduce exhaust noise at the source itself, thus simplifying the task of exhaust system design; and secondly, to asses up to which extent simple linear source models may be used to predict exhaust noise in these engines. The results obtained indicate that, on the one hand, exhaust noise is sensitive to the variation of certain engine design parameters and, on the other hand, that for certain running conditions simple source models may give an acceptable estimation of the actual engine behaviour as a noise source.

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.

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.

This study has been aimed at the reduction of the intense piston skirt friction force that appears in the expansion stroke out of all piston friction forces generated in gasoline engines. The friction characteristics at the piston skirt have been analyzed according to the measured results at piston friction forces and the shapes of wears at the piston skirt in actual engine operations. It is found from the above that the majority of the side force working on each piston is supported by the oil film on the skirt, while only some of the side force is supported by the portion in metallic contact with the cylinder. It is also found through experiments that the metallic contact portion has a great effect on the friction force at the skirt. The effect of piston posture in expansion stroke on the friction force has been also analyzed based on the measured results of piston slap motions.

The demand for fuel-efficient, low-displacement engines for future passenger car applications led to investigations with small DI diesel engines in the advanced engineering department at Mercedes-Benz. Single-cylinder tests were carried out to compare a 2-valve concept with 241 cm3 displacement with a 422 cm3 4-valve design, both operated with a common rail injection system. Mean effective pressures at full load were about 10 % lower with the smaller displacement. With such engines a specific power of 40 kW/I and a specific torque of about 140 Nm/I should be possible. In the current stage of optimization, penalties in fuel economy could be reduced down to values below 3 %. The “4-cylinder DI diesel engine with 1 liter displacement” is an interesting alternative to small 3 cylinder concepts with higher displacement per cylinder. An introduction into series production will not only depend on the potential for further improvement in fuel economy of such small cylinder units.

This paper presents a Computational Fluid Dynamic(CFD) model for the oil pump simulations aimed at better understanding the flow characteristics for improving their designs and reducing product development cycles. Several advanced numerical technologies have been developed to handle the complex geometries of oil pumps and the moving interfaces between the rotating and stationary parts. Two basic oil pump configurations, a vane oil pump and a gerotor oil pump, have been studied with the present method. The numerical results are compared with the existing experimental data.

Into the early-part of the next century, automotive emission standards are becoming stricter around the world. The electrically-heated catalyst (EHC) is well known as an effective technology for the reduction of cold-start hydrocarbon emissions without a significant increase in back pressure. Our extruded, alternator powered EHC (APEHC) manufactured with a unique canning method and equipped with a reliable, water proof electrode has demonstrated excellent durability and reliability, as stated in our previous SAE paper (#960340). The APEHC system discussed in this paper has achieved the Ultra-Low-Emission Vehicle (ULEV) standards, after 100,000 miles of fleet testing, without any failure. This is the final milestone in addressing the EHC as a realistic-production technology for ULEV. With the ability to meet ULEV/Stage III emission targets without a significant increase in back pressure, the EHC will be applied to an especially high performance vehicle with a large displacement engine.

The performance of a low density, ferritic stainless steel foam as a support structure for automotive emission control catalyst was evaluated, using ceramic and ferritic stainless steel foil monoliths for comparison. Results for the pressure drop, light-off time, light-off temperature, air/fuel ratio sweep, and vibration tests (at the room temperature and 1000°C) are presented. These tests were conducted at the Southwest Research Institute (SwRI), San Antonio, TX. Test configurations and procedures that are standardized for testing the ceramic and metal foil monoliths were used. Test results indicated that metallic foams are a viable support structure for automotive catalysts. With the foam-supported catalyst (0.36 L), the conversion of HC, CO and NOx was 90% as efficient as that achieved with catalysts supported on a ceramic monolith (0.62 L) or a metal foil monolith (0.73 L). A need for the optimization of the foam structure and the catalyst formulation was identified.

Air flow through the passages of a Chrysler LH platform ventilated brake rotor is measured. Modifications to the production rotor's vent inlet geometry are prototyped and measured in addition to the production rotor. Vent passage air flow is compared to existing correlations. The inlet modifications show significantly improved vent air flow, over the production rotor. The result improvement in heat transfer and rotor cooling is reported. These benefits in performance should be attainable at very low increases in production cost.