Search Results

One of the key functions of lubricating oil additives in diesel engines is to control oil thickening caused by soot accumulation. Over the last several years, it has become apparent that the composition of the base oil used within the lubricant plays an extremely important role in the oil thickening phenomenon. In particular, oil thickening observed in the Mack T-8 test is significantly affected by the aromatic content of the base oil. We have found that the Mack T-8 thickening phenomenon is associated with high electrical activity, i.e., engine drain oils which exhibit high levels of viscosity increase show significantly higher conductivities. These findings suggest that electrical interactions are involved in soot-induced oil thickening.

A traction test machine, developed for evaluation of traction-CVT fluids for the automotive consortium, USCAR, provides precision traction measurements to stresses up to 4 GPa. The high stress machine, WAMhs, provides an elliptical contact between AISI 52100 steel roller and disc specimens. Machine stiffness and positioning technology offer precision control of linear slip, sideslip and spin. A USCAR traction test methodology includes entrainment velocities from 2 to 10 m/sec and temperatures from -20°C to 140°C. The purpose of the USCAR machine and test methodology is to encourage traction fluid development and to establish a common testing approach for fluid qualification. The machine utilizes custom software, which provides flexibility to conduct comprehensive traction fluid evaluations.

Historically, vehicle fluid condition has been monitored by measuring miles driven or hours operated. Many current vehicles have more sophisticated monitoring methods that use additional variables such as fuel consumption, engine temperature and engine revolutions to predict fluid condition. None of these monitoring means, however, actually measures a fluid property to determine condition, and that is about to change. New sensors and diagnostic systems are being developed that allow real time measurement of some lubricant physical and/or chemical properties and interpret the results in order to recommend oil change intervals and maximize performance. Many of these new sensors use electrochemical or acoustic wave technologies. This paper examines the use of these two technologies to determine engine oil condition and focuses on the effects of lubricant chemistry on interpreting the results.

The work presented here is the second of two papers investigating the KA24E engine test. The first paper characterized the KA24E engine in terms of the physical and chemical operating environment it presents to lubricants. The authors investigated oil degradation and wear mechanisms, and examined the differences between the KA24E and the Sequence VE engine tests. It was shown that while the KA24E does not degrade the lubricant to the extent that occurs in the Sequence VE, wear could be a serious problem if oils are poorly formulated. This second paper examines the wear response of the KA24E to formulation variables. A statistically designed matrix demonstrated that the KA24E is sensitive to levels of secondary zinc dialkyldithiophosphate (ZDP), dispersant and calcium sulfonate detergent. This matrix also showed that the KA24E appears to have good repeatability for well formulated oils and is a reasonable replacement for the wear component of the Sequence VE.

The Nissan KA24E engine test is designated to replace the Ford Sequence VE engine test as the low temperature valve train wear requirement for ILSAC (International Lubricant Standardization and Approval Committee) GF-3. The KA24E (recently designated the Sequence IV A) represents much of the current world-wide material and design technology while retaining the sliding cam/follower contact found in earlier engine designs. The work presented here is the first of two reports. In this first report, the physical and chemical environment the KA24E engine presents a lubricant is characterized and compared to those of the Sequence VE engine. Valve train materials and wear modes are investigated and described. Although chemical analysis of drain oils indicate the KA24E procedure does not degrade the lubricant to the extent seen in the Sequence VE test, valve train wear appears to proceed in a similar manner in both tests.

Throughout the evolution of the automobile, passenger car motor oils have been developed to address issues of wear, corrosion, deposit formation, friction, and viscosity stability. As a result, the internal combustion engines are now developed with the expectation that the lubricants to be used in them will deliver certain performance attributes. Metallurgies, clearances, and built-in stresses are all chosen with certain expectations from the lubricant. A family of chemicals that has been universally used in formulating passenger car motor oils is zinc dithiophosphates (ZDPs). ZDPs are extremely effective at protecting highly stressed valve train components against wear failure, especially in engine designs with a sliding contact between cams and followers. While ZDPs' benefits on wear control are universally accepted, ZDPs have been identified as the source of phosphorus, which deactivates noble metal aftertreatment systems.

The effects of port fuel injection (PFI) timing and targeting on air/fuel (A/F) control, exhaust emissions, and combustion stability at retarded spark timing were investigated on a 2.0L I-4 engine with production injectors (300-350 micron SMD droplet spray). Timings were fully closed valve injection (CVI) or fully open valve injection (OVI), and selected targetings were towards the valve or port floor. An “ideal” pre-vaporized, pre-mixed fuel system was also tested to provide a baseline with which to isolate PFI fuel preparation effects. The key findings were: Transient A/F excursions with PFI were minimized over the full temperature range with OVI timing and valve targeting. The X-tau modeled film mass for OVI/valve target was 50% less than CVI/valve target and 30% less than OVI/port target with a cold engine (20° C). When fully warm (90° C), the A/F response of CVI/valve target improved to near that of OVI.

Seated vertical vibration thresholds were tested using an adaptive Levitt algorithm. All such testing raises issues concerning potential shifting of thresholds during testing as subjects improve at the task. Additional testing was done at 4 and 16 Hz to quantify the adequacy of training within the algorithm. A 3-down 1-up algorithm starting at 8 mG descended in 3 dB steps until the first error, then switched to 1 dB steps and continued for 9 more reversals, with the last 6 averaged for threshold. Stimuli were paired with intervals containing no vibration in random order. Subjects closed their eyes and were presented with sounds in earphones to indicate the stimulus intervals, and chose the interval they thought contained the stimulus. A combination of eyes closed for concentration, gradual approach to the threshold, 4 reversals before data was used, and feedback on each trial provided built-in training to avoid threshold shift.

This study describes the use of Quantitative Structure Activity Relationships (QSAR) to develop predictive models for non-acidic Lubricity agents. The work demonstrates the importance of separating certain chemical families to give better and more robust equations rather than grouping a whole data set together. These models can then be used as important tools in further development work by predicting activities of new compounds before actual synthesis/testing.

Mechanical properties of as-rolled steels used in a vehicle vary with many parameters including gages, steel suppliers and manufacturing processes. The residual forming and strain rate effects of automotive components have been generally neglected in full vehicle crashworthiness analyses. Not having the above information has been considered as one of the reasons for the discrepancy between the results from computer simulation models and actual vehicle tests. The objective of this study is to choose the right material property for as-rolled steels for stamping and crash computer simulation, and investigate the effect of forming and strain rate on the results of full vehicle impact analyses. Major Body-in-White components which were in the crash load paths and whose material property would change in the forming process were selected in this study. The post-formed thickness and yield stress distributions on the components were estimated using One Step forming analyses.

In order to experience harmony among the various perceptual cues experienced by an automobile customer, the acoustic environment must be considered. Acoustic events generated by automotive systems can have a dramatic effect on a customer's impression of vehicle quality and reliability. Additionally, certain vehicle segments are partially defined by the vehicle's sound characteristic. For example, luxury segments are defined by quiet and smooth powertrain sound, whereas some sports car segments are defined by loud and rough powertrain sound. This paper is a discussion of the impact automotive acoustic events can have on the customer. Addressed will be the methods typically used in both data collection and subsequent jury evaluations. Two case studies will be discussed. Finally, there will be a brief discussion on the future role of psychoacoustics in the vehicle environment.

Thermally-sprayed, composite coatings have been developed and sprayed on aluminum engine heads to replace powdered metal valve seat inserts. The process uses a conventional two-wire arc (TWA) gun with nickel and iron-based wire feedstocks. A unique surface preparation technique was developed to assure excellent coating adhesion. A composite Fe/Fe3O4/Ni/NiO/CrO coating was dynamometer tested using a single-cylinder Rotax engine, and showed improved wear performance over a conventional powdered-metal insert. Details of surface preparation, coating development, tribological properties and engine testing are described in this work.

Mist generated from water-soluble fluids used in machining operations represents a potentially significant contribution to worker exposure to airborne particles. Part I of this study [1], discussed polymer additives as mist suppressants for straight mineral oil metalworking fluids (MWF), which have been successfully employed at several locations. This paper focuses on recent developments in polymer mist suppressants for water-based MWF, particularly in the production environment. The polymer developed and tested in this study functions on a similar basis to that for straight oil anti-mist additives. This water soluble polymer suppresses the formation of small mist droplets and results in a distribution of larger droplet sizes. These larger droplets tend to settle out near the point of machining, resulting in a significant decrease in the total airborne mist concentration.

Functioning as an introduction to modern mechanics principles and various applications that deal with the science, mathematics and technical aspects of sheet metal forming, Mechanics Modeling of Sheet Metal Forming details theoretically sound formulations based on principles of continuum mechanics for finite or large deformation, which can then be implemented into simulation codes. The forming processes of complex panels by computer codes, in addition to extensive practical examples, are recreated throughout the many chapters of this book in order to benefit practicing engineers by helping them better understand the output of simulation software.

The search for alternative energy sources, particularly renewable sources, has led to increased activity in the area of ethanol blended diesel fuel, or E diesel. E diesel offers potential benefits in reducing greenhouse gases, reducing dependence on crude oil and reducing engine out emissions of particulate matter. However, there are some concerns about the use of E diesel in the existing vehicle fleet. One of the chief concerns of the use of E diesel is the affect of the ethanol on the lubricating properties of the fuel and the potential for fuel system wear. Additive packages that are used to formulate E diesel fuels can improve fuel lubricity and prevent abnormal fuel system wear. This work studies the lubricity properties of several E diesel blends and the diesel fuels that are used to form them. In addition to a variety of bench scale lubricity tests, injector pump tests were performed as an indicator of long term durability in the field.

This paper is concerned with the use of solid elements in sheet metal forming simulation, particularly springback prediction for flanging when the flanging radii are comparable with the metal thickness. It is demonstrated that appropriate solid elements must be used instead of shell elements in order to obtain adequate results. Numerical difficulties associated with development of suitable solid elements are discussed in detail, with emphasis on the volumetric locking and transverse shear locking phenomena respectively. The transverse shear locking arises from the incompatible deformation modes when the element is used for thin structure bending analysis. A four point bending testing problem is used to study the performances of different solid elements. A locking-free solid element based on assumed strain formulation is developed in Ford in-house program MTLFRM for accurate springback prediction, and a flanging example is given to demonstrate its application.

The primary goal of the USAF JP-8+100 thermal stability additive (TSA) program is to increase the heat-sink capacity of JP-8 fuel by 50%. Current engine design is limited by a fuel nozzle temperature of 325°F (163°C); JP-8+100 has been designed to allow a 100°F increase in nozzle temperatures up to 425°F (218°C) without serious fuel degradation leading to excessive deposition. Previous studies have shown that TSA formulations increase the electrical conductivity of base jet fuel. In the present paper, further characterization of this phenomenon is described, as well as interactions of newer TSAs with combinations of SDA and other surface-active species in hydrocarbons, will be discussed.

The continued development of more powerful aviation turbine engines has demanded greater thermal stability of the fuel as a high temperature heat sink. This in turn requires better definition of the thermal stability of jet fuels. Thermal stability refers to the deposit-forming tendency of the fuel. It is generally accepted that dissolved oxygen initiates the deposition process in freshly refined fuels. While there are many tests that are designed to measure or assess thermal stability, many of these either do not display sufficient differentiation between fuels of average stability (JP-8) and intermediate stability (JP-8+100, JP-TS), or require large test equipment, large volumes of fuels and/or are costly. This paper will discuss the use of three laboratory tests as “concept thermal stability prediction” tools with aviation fuels, including Jet A-1 or JP-8, under JP8+100 test conditions.

The tightening legislation in the on-road heavy-duty diesel area means that pollution control systems will soon be widely introduced on such engines. A number of different aftertreatment systems are currently being considered to meet the incoming legislation, including Diesel Particulate Filters (DPF), Diesel Oxidation Catalysts (DOC) and Selective Catalytic Reduction (SCR) systems. Relatively little is known about the interactions between lubricant-derived species and such aftertreatment systems. This paper describes the results of an experimental program carried out to investigate these interactions within DPF, DOC and SCR systems on a state-of-the-art 9 litre engine. The influence of lubricant composition and lube oil ash level was investigated on the different catalyst systems. In order to reduce costs and to speed up testing, test oil was dosed into the fuel. Tests without dosing lubricant into the fuel were also run.

The present research is concerned with the quality of the shearing process, which is an integral part of automotive vehicle body stamping. Experiments were done to analyse the influence of the gap between the cutting edges and the geometry of the cutting blades, on the quality of the sheared surface. Experimental results are presented as microstructures of polished samples. To predict the quality of sheared surfaces, a numerical code based on solid mechanics equations, elastoplastic flow theory and cummulative theory of damages was created.