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Technical Paper

Optimization of Heavy Duty Diesel Engine Lubricant and Coolant Pumps for Parasitic Loss Reduction

As fuel economy becomes increasingly important in all markets, complete engine system optimization is required to meet future standards. In many applications, it is difficult to realize the optimum coolant or lubricant pump without first evaluating different sets of engine hardware and iterating on the flow and pressure requirements. For this study, a Heavy Duty Diesel (HDD) engine was run in a dynamometer test cell with full variability of the production coolant and lubricant pumps. Two test stands were developed to allow the engine coolant and lubricant pumps to be fully mapped during engine operation. The pumps were removed from the engine and powered by electric motors with inline torque meters. Each fluid circuit was instrumented with volume flow meters and pressure measurements at multiple locations. After development of the pump stands, research efforts were focused on hardware changes to reduce coolant and lubricant flow requirements of the HDD engine.
Journal Article

Design and Implementation of a D-EGR® Mixer for Improved Dilution and Reformate Distribution

The Dedicated EGR (D-EGR®) engine has shown improved efficiency and emissions while minimizing the challenges of traditional cooled EGR. The concept combines the benefits of cooled EGR with additional improvements resulting from in-cylinder fuel reformation. The fuel reformation takes place in the dedicated cylinder, which is also responsible for producing the diluents for the engine (EGR). The D-EGR system does present its own set of challenges. Because only one out of four cylinders is providing all of the dilution and reformate for the engine, there are three “missing” EGR pulses and problems with EGR distribution to all 4 cylinders exist. In testing, distribution problems were realized which led to poor engine operation. To address these spatial and temporal mixing challenges, a distribution mixer was developed and tested which improved cylinder-to-cylinder and cycle-to-cycle variation of EGR rate through improved EGR distribution.
Journal Article

Automated Driving Impediments

Since the turn of the millennium, automated vehicle technology has matured at an exponential rate, evolving from research largely funded and motivated by military and agricultural needs to a near-production market focused on everyday driving on public roads. Research and development has been conducted by a variety of entities ranging from universities to automotive manufacturers to technology firms demonstrating capabilities in both highway and urban environments. While this technology continues to show promise, corner cases, or situations outside the average driving environment, have emerged highlighting scenarios that impede the realization of full automation anywhere, anytime. This paper will review several of these corner cases and research deficiencies that need to be addressed for automated driving systems to be broadly deployed and trusted.
Technical Paper

Numerical and Experimental Characterization of the Dual-Fuel Combustion Process in an Optically Accessible Engine

The dual-fuel combustion process of ethanol and n-heptane was characterized experimentally in an optically accessible engine and numerically through a chemical kinetic 3D-CFD investigation. Previously reported formaldehyde PLIF distributions were used as a tracer of low-temperature oxidation of straight-chained hydrocarbons and the numerical results were observed to be in agreement with the experimental data. The numerical and experimental evidence suggests that a change in the speed of flame propagation is responsible for the observed behavior of the dual-fuel combustion, where the energy release duration is increased and the maximum rate of pressure rise is decreased. Further, an explanation is provided for the asymmetrical energy release profile reported in literature which has been previously attributed to an increase in the diffusion-controlled combustion phase.
Technical Paper

Evaluation of Hydraulic Efficiency Using High-Shear Viscosity Fluids

Fossil fuel consumption is a significant factor in terms of both economic and environ-mental impact of on- and off-highway systems. Because fuel consumption can be directly tied to equipment efficiency, gains in efficiency can lead to reduction in operating costs as well as conservation of nonrenewable resources. Fluid performance has a direct effect on the efficiency of a hydraulic system. A procedure has been developed for measuring a fluid's effect on the degree to which mechanical power is efficiently converted to hydraulic power in pumps typical of off-highway applications.
Journal Article

Multi-Vehicle Evaluation of Gasoline Additive Packages: A Fourth Generation Protocol for the Assessment of Intake System Deposit Removal

Building on two decades of expertise, a fourth generation fleet test protocol is presented for assessing the response of engine performance to gasoline additive treatment. In this case, the ability of additives to remove pre-existing deposit from the intake systems of port fuel injected vehicles has been examined. The protocol is capable of identifying real benefits under realistic market conditions, isolating fuel performance from other effects thereby allowing a direct comparison between different fuels. It is cost efficient and robust to unplanned incidents. The new protocol has been applied to the development of a candidate fuel additive package for the North American market. A vehicle fleet of 5 quadruplets (5 sets of 4 matched vehicles, each set of a different model) was tested twice, assessing the intake valve clean-up performance of 3 test fuels relative to a control fuel.
Technical Paper

Roadmap for Hybridization of Military Tactical Vehicles: How Can We Get There?

The U.S. Army's National Automotive Center has contracted with Illinois Institute of Technology Research Institute (IITRI), Southwest Research Institute (SwRI), and Advanced Propulsion, LLC, to evaluate the effects on fuel consumption and logistics that would result from hybridizing the powertrains of the Army's tactical wheeled vehicle fleet. This paper will outline the approach taken to perform that evaluation and present a synopsis of results achieved to date.
Technical Paper

Operability and Compatibility Characteristics of Advanced Technology Diesel Fuels: Pump Evaluations

Two different laboratory fuel-injection-pump durability-tests were conducted with four advanced technology test fuels. The first test used a relatively low pressure rotary, opposed piston fuel injection pump similar to those used on some current North American engines. The second test used a relatively high pressure common rail injection pump such as those used currently on some European engines. The tests were scheduled to operate for 500 hours under severe load conditions. It can be concluded that the common-rail, high-pressure fuel pump is more sensitive to the advanced fuels than is the rotary pump in this severe duty-cycle test. Although the laboratory high frequency reciprocating rig (HFRR) tests were able to distinguish between those fuels that contained lubricity additives and those that did not, there was little correlation with pump durability results.
Technical Paper

CO2 Pump for the Space Station Advanced Atmosphere Revitalization Subsystem

The current operation of the International Space Station (ISS) calls for the oxygen used by the occupants to be vented overboard in the form of CO2, after the CO2 is scrubbed from the cabin air. Likewise, H2 produced via electrolysis in the oxygen generator is also vented. NASA is investigating the use of the Sabatier process to combine these two product streams to form water and methane. The water is then used in the oxygen generator, thereby conserving this valuable resource. One of the technical challenges to developing the Sabatier reactor is transferring CO2 from the Carbon Dioxide Removal Assembly (CDRA) to the Sabatier reactor at the required rate, even though the CDRA and the Sabatier reactor operate on different schedules. One possible way to transfer and store CO2 is to use a mechanical compressor and a storage tank.
Technical Paper

Characterization of Particle Size Distribution of a Heavy-Duty Diesel Engine During FTP Transient Cycle Using ELPI

Particle number concentrations and size distributions were measured for the diluted exhaust of a 1991 diesel engine during the US FTP transient cycle for heavy-duty diesel engines. The engine was operated on US 2-D on-highway diesel fuel. The particle measurement system consisted of a full flow dilution tunnel as the primary dilution stage, an air ejector pump as the secondary dilution stage, and an electrical low pressure impactor (ELPI) for particle size distribution measurements. Particle number emission rate was the highest during the Los Angeles Non Freeway (LANF) and the Los Angeles Freeway (LAF) segments of the transient cycle. However, on brake specific number basis the LAF had the lowest emission level. The particle size distribution was monomodal in shape with a mode between 0.084 μm and 0.14 μm. The shape of the size distribution suggested no presence of nanoparticles below the lower detection limit of the instrument (0.032 μm), except during engine idle.
Technical Paper

Fuel Lubricity: Statistical Analysis of Literature Data

A number of laboratory-scale test methods are available to predict the effects of fuel lubricity on injection system wear. Anecdotal evidence exists to indicate that these methods produce poor correlation with pump wear, particularly for fuels that contain lubricity additives. The issue is further complicated by variations in the lubricity requirements of full-scale equipment and the test methodologies used to evaluate the pumps. However, the cost of performing full-scale equipment testing severely limits the quantity of data available for validation of the laboratory procedures at any single location. In the present study, the technical literature was reviewed and all previously published data was combined to form a single database of 175 pump stand results. This volume of data allows far more accurate statistical analysis than is possible with tests performed at a single location. The results indicate differences in the effectiveness of the standardized laboratory-scale methods.
Technical Paper

An Overview of Current Automatic, Manual and Continuously Variable Transmission Efficiencies and Their Projected Future Improvements

This paper will overview current production manual, automatic, and continuously variable transmission (CVT) efficiencies and efficiency variations across the industry. For automatic transmissions, efficiencies associated with the pump and the gearbox components will be highlighted along with areas for improvements. Efficiencies associated with various types of pumps such as internal-external, gerotor, hypocycloidal, and variable displacement will be compared. For CVT's a comparison of efficiencies for belt type and toroidal types will be provided, along with an examination of external-external and variable displacement type ball pumps.
Technical Paper

Determination of Wear Index to Predict Fuel Filtration Performance

The Beta ratio and filtration ratio are two common rating systems used to designate the abrasive filtration efficiency of fuel filters. Previous research developed a series of wear curves to predict the effects of abrasive particles of varying sizes on fuel injector performance. Based on this data, a formula was generated to predict injector wear based on the number of 5-, 10-, and 15-μm particles in the effluent. This value is called the wear index. (1,2)1 Various fuel filters with the same manufacturer rating were evaluated on a test engine to determine the wear index for each of these fuel filters. The results demonstrate the differences between these “similar” fuel filters and how the wear index provides additional information as compared to Beta and filtration ratios.
Technical Paper

Filtration Requirements and Evaluation Procedure for a Rotary Injection Fuel Pump

A cooperative research and development program was organized to determine the critical particle size of abrasive debris that will cause significant wear in rotary injection fuel pumps. Various double-cut test dusts ranging from 0-5 to 10-20 μm were evaluated to determine which caused the pumps to fail. With the exception of the 0-5-μm test dust, all other test dust ranges evaluated caused failure in the rotary injection pumps. After preliminary testing, it was agreed that the 4-8-μm test dust would be used for further testing. Analysis revealed that the critical particle size causing significant wear is 6-7 μm. This is a smaller abrasive particle size than reported in previously published literature. A rotary injection pump evaluation methodology was developed. During actual operation, the fuel injection process creates a shock wave that propagates back up the fuel line to the fuel filter.
Technical Paper

Contamination Sensitivity of Automotive Components

System contamination caused by contaminates or small particles built-in, self-generated, or inhaled from environment presents severe problems. The problems include but are not limited to the malfunctioning of valves, pumps, seals and injectors or lock-up of these components; increased wear of bearings, piston rings, and other friction components; and degradated machine performance. In general, system contamination changes a deterministic system into a stochastic system and shortens machinery service life. In this paper, these contamination problems are discussed in categories and associated analysis, testing and computer modeling methodologies are also discussed.
Technical Paper

A Performance Comparison of Various Automatic Transmission Pumping Systems

The pumping system used in a step ratio automatic transmission can consume up to 20% of the total power required to operate a typical automotive transmission through the EPA city cycle. As such, it represents an area manufacturers have focused their efforts towards in their quest to obtain improved transmission efficiency. This paper will discuss the history of automatic transmission pumps that develop up to 300 psi along with a description of the factors used to size pumps and establish pump flow requirements. The various types of pumps used in current automatic transmissions will be described with a discussion of their characteristics including a comparison based upon observations of their performance. Specific attention will be focused on comparing the volumetric efficiency, mechanical efficiency, overall efficiency, pumping torque and discharge flow.
Technical Paper

Proposed Efficiency Rating for an Optimized Automatic Transmission

Increased concern for improving fuel mileage in today's vehicles has focused attention on powertrain component efficiencies. Currently, no efficiency standards exist for automatic transmissions but, uniform testing procedures do exist. Consequently, vehicle and transmission manufacturers have no basis for comparing transmission-to-transmission performance. In addition, manufacturers have no design targets from which to critique their product. This paper addresses this issue by developing an overall transmission efficiency rating. This rating is based upon average transmission operational torques and speeds, the percent time of operation in each gear for a representative duty cycle, and representative efficiencies at these conditions based on test data obtained from a cross section of current production transmissions.
Technical Paper

Investigation of Diesel Spray Structure and Spray/Wall Interactions in a Constant Volume Pressure Vessel

High-speed movie films, and laser-diffraction drop sizing were used to evaluate the structure, penetration rate, cone angle, and drop size distribution of diesel sprays in a constant volume pressure vessel. As further means of evaluating the data, comparisons are made between the film measurements, and calculations from a dense gas jet model. In addition to the high-speed film data that describes the overall structure of the spray as a function of time, a laser diffraction instrument was used to measure drop size distribution through a cross-section of the spray. In terms of the growth of the total spray volume (a rough measure of the amount of air entrained in the spray), spray impingement causes an initial delay, but generally the same overall growth rate as an equivalent unimpeded spray. Agreement between measurements and calculations is excellent for a diesel spray with a 0.15 mm D orifice and relatively high injection pressures.
Technical Paper

Comparison Between Real-Life Dust Samples and Standardized Test Dusts

Soil samples were collected from various geographical areas in the United States and Saudi Arabia. The samples were obtained from U.S. military installations at which off-road maneuvers are conducted. Saudi Arabia samples were obtained from the deserts surrounding Riyadh. The samples were characterized using particle size distributions, elemental analysis, mineral composition and particle angularity. Particle size distributions were determined for simulated fuel cells with intermittent and continual mixing. The results obtained from the world-wide soil sample analyses were compared against AC and PTI SAE fine and coarse test dust results.
Technical Paper

Regenerative Active Suspension on Rough Terrain Vehicles

Progress on the development of active suspension for improving mobility of rough terrain vehicles is being hindered by the potentially high energy requirements. A unique regenerative active suspension system has been conceived and is being developed to provide active suspension with very low energy requirements. Regenerative active suspension consists of multiple variable displacement pumps, each controlling flow to and from hydro-pneumatic struts to control a vehicle's low frequency body motions. When fluid is returned from a strut to a pump, energy is recovered or “regenerated” so that the total energy requirement is very low. This paper presents the results of a study showing the potential of the regenerative active suspension system to improve vehicle control and ride comfort of rough terrain vehicles enhancing mobility while requiring very little additional energy.