Engines, Fuels, Lubricants, and Vehicle Systems

The Institute offers innovative design and development services centered on engines, engine components, special vehicles, and improved emissions controls. It also performs a full range of fuel and lubricant test services for government and commercial clients around the world. SwRI engineers continue to meet clients' performance standards, while also adhering to current and anticipated environmental standards in emissions control as well as vehicle and engine design.

Engine Design and Development

Significant progress has been made in developing and applying contamination analysis, testing, modeling, and simulation methodologies to learn how contaminants affect the performance and longevity of automotive components and systems. SwRI engineers are developing simulations and test protocols that replicate real-world conditions and are helping manufacturers design and build components that will achieve targeted service life under a variety of operating conditions. Contamination-control and equipment protection programs involve air and liquid filter testing, evaluation, and integration, including specification development and systems design.

SwRI engineers successfully adapted synthesis gas technology to improve natural gas engine emissions and efficiency. Synthesis gas is formed on-line prior to reaching the engine as a portion of the natural gas travels through a partial methane oxidation catalyst, thereby increasing the fuel's hydrogen content. The resulting hydrogen-enriched fuel can then be used to increase the flame speed and lean limit of a lean-burn engine or to increase the flame speed in an engine where excess oxygen is replaced by recirculated exhaust gases. This process results in a gas engine with high efficiency and extremely low oxides of nitrogen (NOx) emissions.

SwRI engineers have developed an integrated engine cycle simulation program to help predict engine performance and oxides of nitrogen (NOx) emissions. The simulation code, known as Virtual Indicated Performance of Reciprocating Engines, or VIPRE™, combines solution of the gas dynamics in the intake and exhaust pipe networks with solution of the laws of thermodynamics for cylinders and manifolds. VIPRE™ provides a dynamic model of the air cycle and predicts gas temperatures and pressures throughout the engine. The software has been used to simulate and optimize performance in engines ranging from small single-cylinder, spark-ignited engines to large medium-speed diesel power plants. VIPRE™ offers comprehensive simulations of turbochargers, heat exchangers, mufflers, filters, and other flow network elements. Transient response, timing, noise, emissions predictions, and other parameters can also be explored.

The SwRI-developed Rapid Prototyping Electronic Control System (RPECS), a computer-based tool for real-time powertrain control development, has been used to develop gasoline, diesel, ethanol, methanol, and natural gas engines, as well as a number of hybrid vehicle powertrain configurations. The system provides for engine, transmission, and test cell control, and can be run on a vehicle or a test cell unit. More than 20 RPECS systems have been developed for clients. Refinements continue in signal conditioning, user interface, miniaturization, flexible wiring harness design, and ease of adaptation to new engines.

With deregulation, the electric utility industry is seeing increased market applications for distributed generation. Reciprocating engines, microturbines, and fuel cells are among technologies that provide power at client facilities. SwRI is working with industry and government agencies in developing this technology, primarily in stationary high-efficiency, low-emission, natural gas-powered reciprocating engines. One promising technology uses a diesel pilot to ignite lean-burn natural gas engines. In cooperation with the Gas Research Institute and Cooper Energy Services (CES), SwRI engineers have demonstrated NOx emission levels less than 0.7 grams per brake horsepower-hour, at greater than 38 percent thermal efficiency. Development of this CES-patented micropilot technology continues.

SwRI engineers use radioactive tracer technology (RAT) to study and measure real-time wear in engines as they operate in response to lubricant formulation, internal and external contamination, and engine operating conditions. Recent work extended the use of this technology to investigate erosion, corrosion, and cavitation events in oil- and water-based systems and to develop instrumentation for evaluating material response to fluid chemistries and dynamics. RAT is also used in the real-time measurement of oil consumption and for quantifying the effects on engine emissions of oil consumption and composition.

SwRI is continuing development of homogeneous charge compression ignition (HCCI). The objective is to convert a multi-cylinder, compression-ignition engine to operate in HCCI mode, which significantly decreases emissions of particulates and NOx compared to conventional combustion methods. A NOx reduction of more than 98 percent has been achieved in a single-cylinder research engine, compared to a direct-injection diesel configuration of the same engine, without producing soot. Current efforts focus on implementing HCCI on a multi-cylinder engine. The past year has brought increased control of the HCCI process, better understanding of the effects of different fuels on HCCI, and better characterization of the combustion process. Engineers have also increased the operational speed and load range of HCCI.

SwRI organized a Clean Heavy-Duty Diesel Engine-II (CHDDE-II) cooperative research program to develop emission control technologies to meet NOx and particulate matter goals of 2.0 and 0.070 grams per horsepower-hour (g/hp-hr) in 1997 and 1.0 and 0.035 g/hp-hr in 1999. Several technical solutions for the 1997 emissions goals were identified. Current research concentrates on developing technical solutions for 1999 goals while maintaining diesel engine efficiency and durability. The program is in its third year.

SwRI engineers assess emissions from a 2,500-horsepower diesel engine to help Clean Cam Technology Systems develop a low-emission retrofit kit. Such developments are necessary to help older engines meet stringent California air standards.

Emissions Control

For more than 15 years, the Environmental Protection Agency (EPA) has regulated emissions of particulate matter from cars and trucks. Recent studies have associated fine particulate matter with increases in health risks. In response to these concerns, the EPA has revised ambient air quality standards to control the amount of fine particles smaller than 2.5 micro-meters in diameter. Current research is focusing on the health effects of ultrafine particles smaller than 0.1 micrometers in diameter. As part of this research, SwRI is characterizing particulate emissions from vehicles operating on a variety of fuels. A study for the Coordinating Research Council characterized particle emissions from cars and trucks by size and number. Another study, for the Department of Energy, evaluated a variety of alternative diesel fuels to determine their ability to decrease ultrafine particle emissions in diesel engines. Both projects used a micro-orifice uniform deposit impactor (MOUDI) to characterize the size distribution of particle emissions, and a condensation particle counter (CPC) to determine the number of ultrafine particles emitted. For the EPA, SwRI is also working with the Particle Technology Laboratory of the University of Minnesota to develop an improved means of monitoring the number and mass of ultrafine particles emitted from engines during real-time operation. In addition to the MOUDI and multiple CPCs, an electrical low- pressure impactor and a variety of other particle size discriminators are being used in this study.

Proposals for future emissions regulations indicate more stringent future standards for NOx from all engines. Exhaust gas recirculation (EGR) shows promise for heavy-duty diesels, as well as other engines. Conventional EGR systems generally use a single metering valve, located a considerable distance from the intake manifold, and often use an EGR cooler in between. A problem with this approach is its slow response to rapidly changing engine operating conditions. To overcome this limitation, SwRI researchers introduced cooled EGR at the intake port, reducing the distance between the EGR control valve and the point of EGR injection. The system incorporates a belt-driven pump to transfer pre-turbine exhaust to a storage tank where exhaust gas is cooled and kept at a prescribed pressure. Individual tubes then carry the exhaust to each intake port through individual control valves to assure proper EGR distribution and faster responses to changing engine conditions.

An SwRI technician adjusts an automotive diesel engine used in a program to compare alternative diesel fuel formulations. Emissions tests were conducted for six alternative diesel fuels in a program sponsored by the U.S. Department of Energy Office of Transportation Technologies, in support of the joint industry and government Partnership for a New Generation of Vehicles.

Aftertreatment component suppliers are being called on to develop more efficient emissions reduction systems. In order to obtain optimum performance, these systems need to be integrated into the vehicle's engine and powertrain controls. In the past, the integration process has involved such techniques as elementary biasing of selected sensors and laborious trial-and-error efforts that use experimental circuits in the vehicle's electronic control unit, requiring time and expense from both supplier and original equipment manufacturer. Because the addition of improved catalysts usually requires the modification of emissions in "problem" modes of operation, rather than in the entire engine operating range, SwRI developed a system to achieve selected calibration changes. The emission reduction intercept and control system can be used after problem modes have been identified through the use of a test cycle. After optimum emission benefits have been achieved, modifications can then be made to the control program.

To meet new state goals, the California Air Resources Board (CARB) is proposing new emissions standards for off-road, spark-ignited engines of 25 horsepower or above. Gasoline, liquefied petroleum gas, and natural gas typically fuel such engines. SwRI is supporting CARB with a study of emission reduction technologies that could be applied to category equipment. An emissions baseline was determined for both liquid-cooled and air-cooled engines. Recommended technologies, including closed-loop air and fuel control, three-way catalysts, and air injection, were applied to the engines. Emissions from each engine were substantially reduced, enabling researchers to meet proposed standards.

Since late 1997, SwRI engineers have worked on an internal research program to reduce NOx and particulate matter from diesel engines. Researchers in plasma physics, engine technology, and catalyst technology are combining several novel formulations of lean NOx catalysts with unique pulsed-corona reactor technology to produce impressive reductions in NOx emissions. Early indications are that a synergistic effect is occurring between some catalytic formulations and the plasma, with good success in initial experiments on actual diesel exhaust.

SwRI engineers are evaluating the exhaust emission effects of California reformulated diesel fuel in locomotive engines. Use of "CARB diesel" is required for on-highway trucks in California, where emissions testing has shown reductions of NOx and particulate matter emissions. CARB has considered requiring railroads operating in California to use this type of fuel. The program at SwRI involves emissions testing of three fuels, including CARB diesel, in eight revenue service locomotives. Results will help the state of California and railroads determine if CARB diesel is a cost-effective means of emissions reduction in locomotives.

The Institute evaluates the effects of newly formulated tractor hydraulic fluids using SwRI's tractor dynamometer.

Fuels and Lubricants Research

SwRI engineers have developed an axle efficiency test stand to rank and quantify gear lubricants with respect to hypoid axle performance. By accurately measuring the input and output axle speeds and torques, axle efficiency can be calculated. The test stand uses either Dana models 44 or 60 hypoid axle assemblies and is driven by a variable speed 200 horsepower electric motor capable of pinion input speeds ranging from 0-3,000 revolutions per minute. Input torque, which is controlled by axle loading, is set by adjusting the operating pressure of the hydraulic pump driven by the axle. The computer-controlled system also enables the recording of input and output speeds and torques, as well as oil temperature recorded at an adjustable data collection rate. Specially selected components allow the measurement of small differences between lubricants. Enhanced performance torque meters, along with stable speed control, allow for precise efficiency measurements. A broad range of operating conditions is also possible.

A laboratory-scale test apparatus was developed to evaluate the wear characteristics of fuels and lubricants under high temperature and pressure conditions. The apparatus allows tests to be performed with fluids that are gaseous under ambient conditions and to form a lubricating liquid only under high pressure, such as those seen in the fuel delivery system. The apparatus is also useful for volatile liquids, such as gasoline and diesel fuel, to minimize wear and provide acceptable durability. The new apparatus may perform tests at pressures up to 200 pounds per square inch and 200°C, which is sufficient to simulate most automotive and aviation applications. Aside from temperature and pressure, the apparatus was designed to precisely duplicate the conditions specified in the CEC F-06-T-96, ISO/DIS 12156-1.3, SAE J2265, and ASTM D 6079 standard test procedures.

Over the last few years, SwRI has been developing and standardizing procedures to measure the propensity of a fuel to produce thermal deposits. Such deposits typically form at critical locations within the engine - at the intake valve or within the passageways of fuel injectors. A port fuel injector procedure was developed and is currently undergoing ASTM review for eventual standardization. An SwRI-developed intake valve deposit apparatus is also available, while a purpose-designed apparatus is currently being designed to simulate the L-10 diesel fuel injector deposit test.

Seal compatibility testing at SwRI determines the degree of compatibility of lubricating oils and cured elastomers used in the automotive industry.

SwRI has developed several laboratory-scale procedures to simulate the load-carrying capacity of gear oil lubricants. In the past, these oils were commonly evaluated using complex, time-consuming, full-scale gear tests. Some of the required test procedures are no longer commercially available. SwRI developed a Gear Oil Scuff Test (GOST) to accurately predict lubricant load-carrying capacity and give good correlation with real-world gear scuffing. The GOST procedure has been accepted as an SAE AIR 4978 standard and is currently being reviewed for standardization by ASTM.

The Institute's mileage accumulation dynamometer facility has logged more than 3.3 million miles since 1995. It can accommodate most cars and light trucks and can provide around-the-clock testing. Road-grade simulation was recently incorporated to duplicate routes over elevated terrain. A constant-speed electric motor and clutch provide motoring capability and inertia simulation, while a dynamometer provides braking and speed control. The vehicle's driven wheels transmit power to the unit through 48-inch rolls. Some of this power is used to generate wind speed proportional to the roll speed by means of a 61,000 cubic-feet-per-minute blower. This accurately reproduces the under-hood and under-body temperatures experienced by the engine, drivetrain, and exhaust emission systems during normal driving conditions.

U.S. Army TARDEC Fuels and Lubricants Research Facility

The U.S. Army Tank-Automotive Research, Development, and Engineering Center (TARDEC) Fuels and Lubricants Research Facility (TFLRF) is a government-owned laboratory located on the SwRI grounds and staffed and operated by Institute personnel. The laboratory functions as a dedicated, in-house component of TARDEC, the Department of Defense organization responsible for military ground vehicle fleets. TFLRF assists the military and other federal agencies in investigating and solving problems in fuels, lubricants, and functional fluids technology.

The U.S. military stores vehicles and other combat equipment in strategically located warehouses and aboard pre-positioned ships throughout the world. This equipment is a vital part of the national rapid response force. A persistent problem has been ensuring adequate corrosion protection for the vehicle fleet. To date, the problem has been handled through frequent, possibly unnecessary, engine oil changes to ensure that important preservative additives are functioning properly. As a result of a year-long series of engine, bench-scale, and field evaluations, TARDEC staff demonstrated that key preservation properties in U.S. Army preservative engine oil are retained over at least 150 hours of active field service. These results will allow the Army to revise its maintenance procedures for stored equipment, eliminate unnecessary oil changes, and reduce oil procurement and disposal costs.

Under contract to the Army, the Institute has developed an Integrated Petroleum, Oils, and Lubricants Data System (IPOLDS) for lubricants packaged in containers. The computer-based IPOLDS improves the speed and accuracy of logistics planning. In the past, the quantity of packaged lubricants shipped with a combat unit was based on the number of soldiers deployed. IPOLDS provides a lubricant list based on equipment to be deployed, length of time until a resupply system is in place, and climatic conditions to be encountered. The system also provides lubrication information that was previously only found in lubrication orders and technical manuals.

The White House Commission on Aviation Safety and Security has announced a goal of providing technology to reduce aircraft accident rates by a factor of five within 10 years. Institute engineers contributed to a 1998 report published by the Federal Aviation Administration on the flammability hazard of jet-A fuel vapor in civil transport aircraft fuel tanks.

NASA has committed up to $500 million for a seven-year program that began in fiscal year 1998. SwRI staff have been selected to assist the NASA Lewis Research Center in developing the program plan to address necessary research for a fire-safe aviation fuel.

In 1998, the Institute provided technical assistance to a South African company to develop industry acceptance of synthetic hydrocarbons, derived from coal gasification using the Fischer-Tropsch process, as blending materials in aviation jet fuels. An important part of the project was consultation with engine and airframe manufacturers to determine industry concerns. SwRI scientists subsequently assisted in testing and developing data to satisfy the manufacturers as well as the international organizations responsible for aviation fuel specifications. This successful project represents the first known use of synthetic hydrocarbons in commercial aviation fuel.

Continuously variable transmissions are configured with parts not normally found in conventional transmissions and must deliver consistent and reliable performance through varied environmental conditions. SwRI engineers conduct a series of efficiency, performance, endurance, and environmental tests to bring novel transmissions to production.

Vehicle Systems Design and Development

Hybrid electronic powertrains promise significant improvements in fuel economy. SwRI engineers recently modeled such a powertrain, developed the control hardware and software, designed the mechanical transmission hardware, and prototyped the transmission. Laboratory and engine-driven dynamometer, environmental, and emissions testing followed. Comparative testing between a current production passenger car and the SwRI-developed system indicated a significant fuel economy improvement with the hybrid powertrain.

SwRI is completing an internal research program that has developed the PECOS (Parallel Hybrid Electric Combination of Speeds) powertrain, a set of capabilities that allows development of powertrain systems from simulation and design through fabrication and testing. Powertrain control strategies were simulated with several configurations before the hardware was commissioned. After components were selected and controls were defined, a "virtual" powertrain was designed to test for strength, tolerance, fit, and assembly. After fabrication, the control system was implemented using RPECS, which allowed engineers to adjust the control strategy during testing.

SwRI completed a third year of software development to model advanced powertrains that support the Partnership for a New Generation of Vehicles and its goal to develop a passenger vehicle that achieves up to 80 miles per gallon. Control strategies have been developed, and acceptance testing by major automobile manufacturers has been completed. The software will be distributed within the car companies, the U.S. Army National Automotive Center, NASA, Oakland University, the University of Michigan, and the Department of Energy.

The advent of fast gate, turn-off electronic power semiconductors has brought new and innovative applications of power conversions in telecommunications, industrial electric drives, electric power generation and distribution, and electric and hybrid vehicles. As ultracapacitors and other advanced energy storage devices have become viable sources of storage for auxiliary power requirements, the need has grown for a bi-directional DC/DC power converter with step-up and step-down capabilities. SwRI engineers recently began an internal research program to design and simulate an advanced electronic power conversion topology and its controller, targeted initially for an ultracapacitor interface for hybrid electric vehicles.

Vehicle manufacturers are constantly challenged to determine if new technologies can be applied to their products and if the risks justify development. To assist a client in determining transmission configurations 10 years into the future, engineers wrote 13 articles, covering technologies ranging from ceramics and instrumentation to hydraulic fluids and electronic controls. Based on this research, 10 mechanical, hydraulic, and electrical transmissions were developed, from which a novel transmission was selected that provided the manufacturer with a competitive edge over producers of similar vehicles. As part of this effort, 11 invention disclosures were generated and their rights transferred to the client.

1998 Annual Report SwRI Home