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All around the world, steps are being taken to improve the quality of our environment. Prominent among these are the definition, implementation, and attainment of increasingly stringent emissions regulations for all types of engines, including off-highway diesels. These rigorous regulations have driven use of technologies like after-treatment, advanced air systems, and advanced fuel systems. Fuel dispensed off-highway is routinely and significantly dirtier than fuel from on-highway outlets. Furthermore, fuels used in developing countries can be up to 30 times dirtier than the average fuels in North America. Poor fuel cleanliness, coupled with the higher pressures and performance demands of modern fuel systems, create life challenges greater than encountered with cleaner fuels. This can result in costly disruption of operations, loss of productivity, and customer dissatisfaction in the off-highway market.

In recent years, Nearfield Acoustical Holography (NAH) has been used to identify stationary vehicle exterior noise sources. However that application has usually been limited to individual components. Since powertrain noise sources are hidden within the engine compartment, it is difficult to use NAH to identify those sources and the associated partial field that combine to create the complete exterior noise field of a motor vehicle. Integrated Nearfield Acoustical Holography (INAH) has been developed to address these concerns: it is described here. The procedure entails sensing the sources inside the engine compartment by using an array of reference microphones, and then calculating the associated partial radiation fields by using NAH. In the second part of this paper, the use of farfield arrays is considered. Several array techniques have previously been applied to identify noise sources on moving vehicles.

This paper describes the capabilities and use of in-vehicle data acquisition and analysis tools that are being developed to help calibration engineers develop and refine vehicle calibrations for good driveability performance. The paper describes the functionality of the tools and gives examples of their use.

Vehicle driveability is now one of the keystones of product quality, and is refined aggressively to achieve product differentiation and market position. The work reported here gives the status of activities aimed at the development of metrics for driveability, and the use of automated analysis tools to help correlate subjective ratings with characteristics derived from measurement.

This paper presents engine performance and emission results that demonstrate a high degree of correlation between tests performed on a transient engine dynamometer with simulated vehicle characteristics, and test performed on a chassis rolls with a vehicle. The transient testing methodology that has been developed is being used to underpin the transfer of vehicle calibration activity to the testbed.

A full calibration exercise of a diesel engine air path can take months to complete (depending on the number of variables). Model-based calibration approach can speed up the calibration process significantly. This paper discusses the overall calibration process of the air-path of the Cat® C7.1 engine using statistical machine learning tool. The standard Cat® C7.1 engine's twin-stage turbocharger was replaced by a VTG (Variable Turbine Geometry) as part of an evaluation of a novel air system. The changes made to the air-path system required a recalculation of the air path's boost set point and desired EGR set point maps. Statistical learning processes provided a firm basis to model and optimize the air path set point maps and allowed a healthy balance to be struck between the resources required for the exercise and the resulting data quality.

Previous research has shown that the homogeneous charge compression ignition (HCCI) combustion concept holds promise for reducing pollutants (i.e. NOx, soot) while maintaining high thermal efficiency. However, it can be difficult to control the operation of the HCCI engines even under steady state running conditions. Power density may also be limited if high inlet air temperatures are used for achieving ignition. A methodology using a small pilot quantity of diesel fuel injected during the compression stroke to improve the power density and operation control is considered in this paper. Multidimensional computations were carried out for an HCCI engine based on a CAT3401 engine. The computations show that the required initial temperature for ignition is reduced by about 70 K for the cases of the diesel pilot charge and a 25∼35% percent increase in power density was found for those cases without adversely impacting the NOx emissions.

Fundamental understanding of the sources of fuel-derived Unburned Hydrocarbon (UHC) emissions in heavy duty diesel engines is a key piece of knowledge that impacts engine combustion system development. Current emissions regulations for hydrocarbons can be difficult to meet in-cylinder and thus after treatment technologies such as oxidation catalysts are typically used, which can be costly. In this work, Computational Fluid Dynamics (CFD) simulations are combined with engine experiments in an effort to build an understanding of hydrocarbon sources. In the experiments, the combustion system design was varied through injector style, injector rate shape, combustion chamber geometry, and calibration, to study the impact on UHC emissions from mixing-controlled diesel combustion.

This paper describes a practical approach used within the UK contribution to the UNECE PMP study in adopting some of the recommendations stated in the draft 2007 regulations for the measurement of particulate mass emissions from heavy-duty diesel engines in the US. This approach was named “2007PM” but the intention was to align rather than fully comply with the draft requirements for the US. In the PMP test work, four main changes were made to the standard European method of particulate emissions measurement (SPM). These were adopted as the 2007PM method. These were the application of a cyclone pre-classifier to 2007PM - with a 50% cut-size at 2.5μm, the use of a single 47mm filter rather than primary and back-up filters, close control of the filter face temperature to 47°C +/-5°C by heating of the dilution air and an increased filter face velocity. Measurements were predominantly made from aerosols generated by engines equipped with Diesel Particulate Filters (DPFs).

A two-color Particle Image Velocimetry (PIV) technique has been applied to a single cylinder, cup-in-head two-stroke research engine. In the two-color PIV, two wavelengths are used to successively record, at a known time separation, the positions of the particulate seeds in the flowfield. By separately interrogating the two images of different color and cross-correlating them, a two-dimensional velocity field is obtained. Since the sequence of the images is known, directional ambiguity is eliminated and two-color PIV can be used to study complex flows. The technique is here applied for the first time to an engine in the presence of combustion. The presence of combustion light complicates the application of two-color PIV because narrow band-pass laser line filters can not be used to reject it, however a suitable combination of laser power, colored glass filters and thresholding during interrogation allowed sufficiently high quality images to be obtained.

A two-color Particle Image Velocimetry (PIV) technique has been applied to a motored single cylinder two-stroke motored research engine. In two-color PIV, two light sheets of different wavelengths are used to successively record, at a known time separation, the positions of the particulate seeds in the flowfield. By separately interrogating the two images of different color and cross-correlating them, a two-dimensional velocity field is obtained. Since the sequence of the images is known, directional ambiguity is eliminated and two-color PIV can be used to study complex, recirculating flows such as those found in an internal combustion engine. The technique is used here to measure the flow in the cup of a motored, single cylinder, cup-in-head, research engine operating with high swirl. Velocity fields were measured at several planes parallel to the piston crown. Multiple images were obtained at each plane, and ensemble averaged velocity and velocity fluctuation were determined.

Clutches are commonly utilised in passenger type and off-road heavy-duty vehicles to disconnect the engine from the driveline and other parasitic loads. In off-road heavy-duty vehicles, along with fuel efficiency start-up functionality at extended ambient conditions, such as low temperature and intake absolute pressure are crucial. Off-road vehicle manufacturers can overcome the parasitic loads in these conditions by oversizing the engine. Caterpillar Inc. as the pioneer in off-road technology has developed a novel clutch design to allow for engine downsizing while vehicle’s performance is not affected. The tribological behaviour of the clutch will be crucial to start engagement promptly and reach the maximum clutch capacity in the shortest possible time and smoothest way in terms of dynamics. A multi-body dynamics model of the clutch system is developed in MSC ADAMS. The flywheel is introducing the same speed and torque as the engine (represents the engine input to the clutch).

A new “Traveling Spark Ignition” (TSI) system which, aided by a Lorentz force, propels a large plasma into the chamber of internal combustion engines, has been developed and tested on a single cylinder 4-stroke engine run on natural gas. Engine test scenarios included: conventional spark plugs with high energy CDI (1ms duration) as well as the new TSI electronics, and specially designed TSI spark plugs with TSI electronics. The TSI system was well suited for conditions where there is poor mixing of air and fuel, greatly reducing misfires. The lean limit was improved by between 6 and 23%. Improvements of nitrogen oxide (NO) emissions when the engine was running at the lean operating limit were up to 80%. One of the TSI plugs was successfully run in an engine at 2100rpm for 50 hours.

This paper presents a response to the question: Simulation - mathematical manipulation or useful design tool? A mathematical model of a modulating valve in a transmission control system was developed to predict clutch pressure modulation characteristics. The transmission control system was previously reported in SAE Paper 850783 - “Electronic/Hydraulic Transmission Control System for Off-Highway Vehicles”. The comparison of simulation predictions with test data illustrates the effectiveness of simulation as a design tool. THE EVOLUTION OF COMPUTER hardware and simulation software has resulted in increased interest and usage of simulation for dynamic analysis of hydraulic systems. Most commercially available software is relatively easy to learn to use. The application of such software and the modeling techniques involved require a longer learning curve.

This paper reports on a comprehensive, crank-angle transient, three dimensional, computational fluid dynamics (CFD) model of the complete lubrication system of a multi-cylinder engine using the CFD software Simerics-Sys / PumpLinx. This work represents an advance in system-level modeling of the engine lubrication system over the current state of the art of one-dimensional models. The model was applied to a 16 cylinder, reciprocating internal combustion engine lubrication system. The computational domain includes the positive displacement gear pump, the pressure regulation valve, bearings, piston pins, piston cooling jets, the oil cooler, the oil filter etc… The motion of the regulation valve was predicted by strongly coupling a rigorous force balance on the valve to the flow.

This paper describes the development of a transient engine test facility for drive cycle simulation and emissions and performance testing. Results are presented to demonstrate correlation with vehicle tests performed on chassis rolls. The tools and techniques developed in the work are discussed.

The effects of thermal and chemical aging on the performance of cordierite-based and high-porosity mullite-based diesel particulate filters (DPFs), were quantified, particularly their filtration efficiency, pressure drop, and regeneration capability. Both catalyzed and uncatalyzed core-size samples were tested in the lab using a diesel fuel burner and a chemical reactor. The diesel fuel burner generated carbonaceous particulate matter with a pre-specified particle-size distribution, which was loaded in the DPF cores. As the particulate loading evolved, measurements were made for the filtration efficiency and pressure drop across the filter using, respectively, a Scanning Mobility Particle Sizer (SMPS) and a pressure transducer. In a subsequent process and on a different bench system, the regeneration capability was tested by measuring the concentration of CO plus CO2 evolved during the controlled oxidation of the carbonaceous species previously deposited on the DPF samples.

Thermal efficiencies of 54% have been demonstrated by single cylinder engine testing of advanced diesel engine concepts developed under Department of Energy funding. In order for these concept engines to be commercially viable, cost effective and durable systems for insulating the piston, head, ports and exhaust manifolds will be required. The application and development of new materials such as thick thermal barrier coating systems will be key to insulating these components. Development of test methods to rapidly evaluate the durability of coating systems without expensive engine testing is a major objective of current work. In addition, a novel, low cost method for producing thermal barrier coated pistons without final machining of the coating has been developed.

Although soot-formation processes in diesel engines have been well characterized during the mixing-controlled burn, little is known about the distribution of soot throughout the combustion chamber after the end of appreciable heat release during the expansion and exhaust strokes. Hence, the laser-induced incandescence (LII) diagnostic was developed to visualize the distribution of soot within an optically accessible single-cylinder direct-injection diesel engine during this period. The developed LII diagnostic is semi-quantitative; i.e., if certain conditions (listed in the Appendix) are true, it accurately captures spatial and temporal trends in the in-cylinder soot field. The diagnostic features a vertically oriented and vertically propagating laser sheet that can be translated across the combustion chamber, where “vertical” refers to a direction parallel to the axis of the cylinder bore.

The development of a simple CVS particulate test and its application to various engine types is shown to quantify a number of problem areas. Research into the reduction of particulates in exhaust gases can be carried out more effectively by this technique than by the older optical methods. These investigations however lag far behind those into the better known gaseous emissions.