Search Results

A technique for evaluating high temperature oxidation and corrosion tendencies of automotive crankcase lubricants is described. The technique utilizes a versatile bench apparatus which, with a minimum of modification, can be used for either evaluating thermal oxidation stability of gear lubricants or oxidation-corrosion tendencies of automotive crankcase lubricants. The apparatus is relatively compact and requires a minimal lubricant sample. Design of the apparatus permits close control of all operating parameters and provides satisfactory test data repeatability. Retainable copper-lead test bearings are used as the indicator in predicting a pass or fail of fully formulated crankcase lubricants as in the case of the CRC L-38-559 (Federal Test Method 3405) technique. Engine and bench test data are compared to illustrate the capabilities of this new bench technique.

The growing usage of Unmanned Aerial Vehicles (UAVs) for aerial surveillance and reconnaissance in military applications calls for lightweight, reliable powerplants that burn heavy distillate fuels. While mass-produced engines exist that provide adequate power-to-weight ratio in the low power class needed for UAVs, they all use a spark-ignited combustion system that requires high octane fuels. Southwest Research Institute (SwRI) has embarked upon an internal research effort to design and demonstrate an engine that will meet the requirements of high power density, power output compatible with small unmanned aircraft, heavy-fuel combustion, reliable, durable construction, and producible design. This effort has culminated in the successful construction and operation of a demonstrator engine.

As on-highway, heavy-duty diesel engine designs have evolved to meet tighter emissions specifications and greater customer requirements, the crankcase environment for heavy-duty engine lubricants has changed. Engine lubricant quality is very important to help ensure engine durability, engine performance, and reduce maintenance downtime. Beginning in the late 1980's, a new Mack genuine oil specification and a new American Petroleum Institute (API) heavy-duty engine lubricant category have been introduced with each new U.S. heavy-duty, on-highway emissions specification. This paper documents the history and development of the Mack T-7, T-8, T-8A, T-8E, T-9, T-10, T-11, and T-12 engine lubricant tests.

More stringent emission legislation has been a driver for changes in the design of Heavy Duty Diesel engines since the 1980s. Optimization of the combustion processes has lead to significant reductions of exhaust emission levels over the years. However, in the year 2002, diesel engines in the USA will have to meet an even more stringent set of emission requirements. Expectations are that this will force most engine builders to incorporate Exhaust Gas Recirculation (EGR). Several studies of the impact of EGR on lubricant degradation have shown increased levels of contamination with soot particles and acidic components. Both of these could lead to changes in lubricant requirements. The industry is developing a new specification for diesel engine lubricants, PC-9, using test procedures incorporating engines with EGR.

This paper describes the design and functionality of an in-situ air entrainment measuring device for analysis of the air entrainment and air release properties of lubricating fluids. The apparatus allows for a variety of measurement techniques for the aeration and deaeration of the lubricating fluid at various temperatures, pressures, and agitation speeds. This test apparatus is patent pending because of its unique ability to allow for continuous, in-situ measurement of the fluid properties and the rates of change of these properties. Most other measurement techniques and apparatuses do not allow for uninterrupted measurement. This apparatus is also unique in that it is capable of detecting minor fluid density changes at a lower level and with more accuracy than all other current techniques or apparatuses.

Next generation vehicles are under environmental and economic pressure to reduce emissions and increase fuel economy, while maintaining the same ride and performance characteristics of present day combustion engine automobiles. This has prompted researchers to investigate hybrid vehicles as one possible solution to this challenge. At Southwest Research Institute (SwRI), a unique parallel hybrid drivetrain was designed and prototyped. This hybrid drivetrain alleviates the disadvantages of series hybrid drivetrains by directly coupling the driving wheels to two power sources, namely an engine and an electric motor. At the same time, the design allows the engine speed to be decoupled from the vehicle speed, allowing the engine to operate at its most efficient state. This paper describes the drivetrain, its components, and the test stand that was assembled to test the parallel hybrid drivetrain.

A Single Cylinder Medium Speed diesel engine research facility has been developed for investigating areas of current technical concern to the rail, marine and stationary power industries. The design and operation of this Single Cylinder Research Engine (SCRE) is described. The facility is centered around a Bombardier model 251-plus 11.0 L engine which is representative of four stroke multi-cylinder railroad, marine and small stationary powerplant engines. All engine support systems (air, cooling water, fuel oil and lubricating oil pumps) operate independent of the engine enabling a wide range of adjustments in flow, pressure and temperature. Current program areas for which this system is used include alternative fuels evaluation, combustion analyses, fuel injection system development, component wear and durability studies, engine friction analyses, lubricant testing and emissions evaluations.

A unique single cylinder engine was used to assess engine performance and combustion characteristics at three different strokes, with all other variables held constant. The engine utilized a production four-valve, pentroof cylinder head with an 86mm bore. The stock piston was used, and a variable deck height design allowed three crankshafts with strokes of 86, 98, and 115mm to be tested. The compression ratio was also held constant. The engine was run with a controlled boost-to-backpressure ratio to simulate turbocharged operation, and the valve events were optimized for each operating condition using intake and exhaust cam phasers. EGR rates were swept from zero to twenty percent under low and high speed conditions, at MBT and maximum retard ignition timings. The increased stroke engines demonstrated efficiency gains under all operating conditions, as well as measurably reduced 10-to-90 percent burn durations.

Sound absorption is one way to control noise in automotive passenger compartments. Fibrous or porous materials absorb sound in a cavity by dissipating energy associated with a propagating sound wave. The objective of this study was to evaluate the acoustic performance of a cotton fiber absorbing material in comparison to a new polypropylene fibrous material, called ECOSORB ®. The acoustical evaluation was done using measurements of material properties along with sound pressure level from road testing of a fully-assembled vehicle. The new polypropylene fibrous material showed significant advantages over the cotton fiber materials in material properties testing and also in-vehicle measurements. In addition to the performance benefits, the polypropylene absorber provided weight savings over the cotton fiber material.

With government mandates, original equipment manufacturers are increasingly focusing on fuel economy and finding efficiency gains throughout the vehicle. Lubricant companies have been asked to design fluids that aid in this effort. Demonstrating real gains becomes complex given the intricacies of these systems and methods range from bench top screen tests to component test stands to full vehicle testing. This paper addresses the variation that was encountered when testing automatic transmission fluid efficiency within a full vehicle test. While it is well known that variability in testing conditions such as engine load or vehicle speed will lead to variability in results, the magnitude of their impact on average throughout the test cycle suggests that repeat testing may not be sufficient to guard against improper conclusions.

It has been shown within the catalyst industry that the emission performance with higher cell density technology and therefore with higher specific geometric area is improved. The focus of this study was to compare the overall performance of high cell density catalysts, up to 1600cpsi, using a MY 2001 production vehicle with a 4.7ltr.V8 engine. The substrates were configured to be on the edge of the design capability. The goal was to develop cost optimized systems with similar emission and back pressure performance, which meet physical and production requirements. This paper will present the results of a preliminary computer simulation study and the final emission testing of a production vehicle. For the pre-evaluation a numerical simulation model was used to compare the light-off performance of different substrate designs in the cold start portion of the FTP test cycle.

Chassis dynamometer tests are often used to determine vehicle fuel economy (FE). Since the entire vehicle is used, these methods are generally accepted to be more representative of ‘real-world’ conditions than engine dynamometer tests or small-scale bench tests. Unfortunately, evaluating vehicle fuel economy via this means introduces significant variability that can readily be mitigated with engine dynamometer and bench tests. Recently, improvements to controls and procedures have led to drastically improved test precision in chassis dynamometer testing. Described herein are chassis dynamometer results from five fully formulated engine oils (utilizing improved testing protocols on the Federal Test Procedure (FTP-75) and Highway Fuel Economy Test (HwFET) cycles) which not only show statistically significant FE changes across viscosity grades but also meaningful FE differentiation within a viscosity grade where additive systems have been modified.

Noise due to the flow over an automobile A-pillar rain gutter in isolation was computed using a two step procedure. Initially the flow solution was obtained by solving the Reynolds Averaged Navier Stokes (RANS) equations. Acoustical Sources were extracted from the flow solution and propagated to the far-field using the Lighthill-Curle equation. Experiments were conducted to evaluate the computations. Compared results include steady pressures, time dependent pressures, and sound intensity levels. Computed results and experimental data were reduced in a similar way to ensure a one to one comparison. Computed results are in good agreement with the experimental values. A-weighted noise levels are predicted reasonably well.

Enhancement of fuel/air mixing is one path towards enabling future diesel engines to increase efficiency and control emissions. Air-assist fuel injections have shown potential for low pressure applications and the current work aims to extend air-assist feasibility understanding to high pressure environments. Analyses were completed and carried out for traditional high pressure fuel-only, internal air-assist, and external air-assist fuel/air mixing processes. A combination of analytical 0-D theory and 3D CFD were used to help understand the processes and guide the design of the air-assisted setup. The internal air-assisted setup was determined to have excellent liquid fuel vaporization, but poorer fuel dispersion than the traditional high-pressure fuel injections.

A turbocharged 2.0 L PFI engine was modified to operate in a low-pressure loop and Dedicated EGR (D-EGR®) engine configuration. Both engine architectures were operated with a low and high octane gasoline as well as three ethanol blends. The core of this study focused on examining combustion differences at part and high loads between the selected fuels and also the different engine configurations. Specifically, the impact of the fuels on combustion stability, burn rates, knock mitigation, required ignition energy, and efficiency were evaluated. The results showed that the knock resistance generally followed the octane rating of the fuel. At part loads, the burn rates, combustion stability, and EGR tolerance was marginally improved with the high ethanol blends. When combustion was not knock or stability limited, the efficiency differences between the fuels were negligible. The D-EGR engine was much less sensitive to fuel changes in terms of burn rates than the LPL EGR setup.

This work provides an effective engineering method of building a part-load engine simulation model from a wide-open throttle (WOT) engine model and available dynamometer data. It shows how to perform part-load engine simulation using optimizer for targeted manifold absolute air pressure (MAP) on a basic matrix of engine speed and MAP. Key combustion parameters were estimated to cover the entire part-load region based on affordable assumptions and limitations. Engine rubbing friction and pumping friction were combined to compare against the motoring torque. The emission data from GM dynamometer laboratory were used to compare against engine simulation results after attaching the RLT sensor to record emission data in the engine simulation model.

Through aggressive application of the Miller Cycle, using two-stage turbocharging, medium speed diesel marine and stationary power engines are demonstrating over 30 bar rated power BMEP, and over 50 percent brake thermal efficiency. The objective of this work was to use engine cycle simulation to assess the degree to which the aggressive application of the Miller Cycle could be scaled to displacements and speeds more typical of medium and heavy truck engines. A 9.2 liter six-cylinder diesel engine was modeled. Without increasing the peak cylinder pressure, improved efficiency and increased BMEP was demonstrated. The level of improvement was highly dependent on turbocharger efficiency - perhaps the most difficult parameter to scale from the larger engines. At 1600 rpm, and a combined turbocharger efficiency of 61 percent, the baseline BMEP of 24 bar was increased to over 26 bar, with a two percent fuel consumption improvement.

A unique two-stroke engine design is investigated in which fresh mixture is introduced into the cylinder through a valve in the piston crown, and exhausted through peripheral cylinder ports. The engine behaves as a free-piston engine through a portion of the cycle when the piston lifts off the valve seat. The fresh air jet rising along the cylinder centerline effectively displaces the burned gases with little mixing of the two streams. The concept was analyzed by a combination of dynamic cycle simulation and prediction of the in-cylinder flow characteristics by multidimensional modeling. The cycle simulation program considered the dynamics of the piston during its free motion as well as under the kinematic constraints of the crank system. A zero-dimensional thermodynamic model of the cylinder was used to predict cycle pressure and temperature, indicated power, fuel consumption, and flow in and out of the cylinder.

In recent years, the slip lock-up mechanism has been adopted widely, because of its fuel efficiency and its ability to improve NVH. This necessitates that the automatic transmission fluid (ATF) used in automatic transmissions with slip lock-up clutches requires anti-shudder performance characteristics. The test methods used to evaluate the anti-shudder performance of an ATF can be classified roughly into two types. One is specified to measure whether a μ-V slope of the ATF is positive or negative, the other is the evaluation of the shudder occurrence in the practical vehicle. The former are μ-V property tests from MERCON® V, ATF+4®, and JASO M349-98, the latter is the vehicle test from DEXRON®-III. Additionally, in the evaluation of the μ-V property, there are two tests using the modified SAE No.2 friction machine and the modified low velocity friction apparatus (LVFA).

The U.S. Army has long identified the need for rapid, reliable methods for analysis of fuels and lubricants on or near the battlefield. The analysis of fuels and lubricants under battlefield or near-battlefield conditions requires that the equipment be small, portable, rugged, quick, and easy to use. Over the past 15 to 20 years, several test kits and portable laboratories have been developed in response to this need. One instrumental technique that has been identified as a likely candidate to meet this need is near-infrared spectroscopy (NIR). To evaluate NIR as a candidate, a set of 280 fuel samples was used. This sample set contained samples of diesel fuel grades 1 and 2, Jet A-l, JP-5, and JP-8. Inspection data were collected on all the fuels as sample size permitted. Each sample was then scanned using a near-infrared spectrometer. Data analysis, model building, and calibration were conducted using a software package supplied with the instrument.