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Vehicle designers make use of vehicle performance programs such as RAPTOR™ to predict the performance of concept vehicles over ranges of industry standard drive cycles. However, the accuracy of such predictions may be greatly influenced by factors requiring more specialist simulation capabilities. For example, fuel economy prediction will be heavily influenced by the performance of the engine cooling system and its impact on the vehicle's aerodynamic drag, and the load from the air-conditioning system. To improve the predictions, specialist simulation capabilities need to be applied to these aspects, and brought together with the vehicle performance calculations through co-simulation. This paper describes the approach used to enable this cosimulation and the benefits achieved by the vehicle designer.

Life prediction and reliability analysis of a cam roller system were investigated. From the tribological analysis, the cam roller system was found to operate under low film parameter conditions and components were subjected to the risk of contact fatigue. Surface analysis performed on the failed rollers indicated that the surface distress was the primary cause for failure. Then, numerical analyses were performed to evaluate the cam roller life and its related reliability. The adopted approach combined a contact fatigue crack growth calculations with a probabilistic model for controlling the design uncertainty. The computation-efficient Fast Probabilistic Integration (FPI™) code was used to solve the problem. With appropriate descriptions for uncertainty distributions, the surface fatigue life of the specified cam roller system can be predicted along with a confident reliability level.

To aid in the catalytic converter design and development process, a test apparatus was designed and built which will allow comparative evaluation of the durability of candidate mat materials under highly controlled thermal and vibration environments. The apparatus directly controls relative shear deflection between the substrate and can to impose known levels of mat material strain while recording the transmitted shear force across the mat material. Substrate and can temperatures are controlled at constant levels using a resistive thermal exposure (RTE) technique. Mat material fatigue after several million cycles is evident by a substantial decrease in the transmitted force. A fragility test was found to be an excellent method to quickly compare candidate materials to be used for a specific application. Examples of test results from several materials are given to show the utility of the mat material evaluation technique.

Alternative fuels are being evaluated in automotive applications in both commercial and government fleets in an effort to reduce emissions and United States dependence on diesel fuel. Vehicles and equipment have been operated using 100 percent biodiesel and various blends of biodiesel and diesel fuel in a variety of applications, including farming equipment and transit buses. This government study investigates the compatibility of four base fuels and six blends with elastomer and metallic components commonly found in fuel systems. The physical properties of the elastomers were measured according to American Society of Testing and Materials (ASTM) D 471, “Standard Test Method for Rubber Property-Effect of Liquids,” and ASTM D 412, “Standard Test Methods for Rubber Properties in Tension.” These evaluations were performed at 51.7°C for 0, 22, 70, and 694 hours. Tensile strength, hardness, swell, and elongation were determined for all specimens.

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.

Aftertreatment durability demonstration is a required validation exercise for on-road medium and heavy-duty diesel engine certification. The demonstration is meant to validate emissions compliance for the engine and aftertreatment system at full useful life or FUL. Current certification practices allow engine manufacturers to complete partial aging and then extrapolate emissions performance results to FUL. While this process reduces the amount of service accumulation time, it does not consider changes in the aftertreatment deterioration rate. Rather, deterioration is assumed to occur at a linear rate, which may lead to false conclusions relating to emissions compliance. With CARB and EPA’s commitment to the reduction of criteria emissions, emphasis has also been placed on revising the existing certification practices. The updated practices would require engine manufacturers to certify with an aftertreatment system aged to FUL.

An Automatic Tire Inflation System (ATIS), specifically designed for use on commercial long haul trailers underwent complete testing and evaluation in 1993/1994.1 Testing and evaluation included a field test of a prototype system and a controlled laboratory evaluation of the Rotary Union which is the only component subject to wear. The testing of the prototype system indicated that design improvements were necessary before the system could be installed in fleet operations. The design improvements were completed and field installation of production ATIS began. The design improvements were intended to improve overall system durability, decrease installation time, to have less effect on the axle structure than the original design, implement the use of SAE or DOT Approved pressure components and increase overall dependability of the system. ATIS systems have now been developed and tested for most domestic trailer axle configurations.

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.

The introduction of the continuously variable transmission (CVT) by General Motors required the introduction of a test to evaluate fluid for the ECOTEC VTi transmission. With assistance from Van Doorne's Transmissie (VDT), the belt and sheave supplier for the transmission, a rig was constructed to test fluids in a transmission-like environment without the variability of in-vehicle testing. The test schedule includes testing for fluid friction coefficient, shear stability, and wear rating and is currently subject to further work aimed at confirming repeatability and discrimination. Once confirmed, the new procedure will become part of the DEX-CVT® specification for the new service fluids for the VT20/25E transmissions.

The study described in this paper covers the development of the Sequence IVB low-temperature valvetrain wear test as a replacement test platform for the existing ASTM D6891 Sequence IVA for the new engine oil category, ILSAC GF-6. The Sequence IVB Test uses a Toyota engine with dual overhead camshafts, direct-acting mechanical lifter valvetrain system. The original intent for the new test was to be a direct replacement for the Sequence IVA. Due to inherent differences in valvetrain system design between the Sequence IVA and IVB engines, it was necessary to alter existing test conditions to ensure adequate wear was produced on the valvetrain components to allow discrimination among the different lubricant formulations. A variety of test conditions and wear parameters were evaluated in the test development. Radioactive tracer technique (RATT) was used to determine the wear response of the test platform to various test conditions.

American Society for Testing and Materials (ASTM) Sequence III Engine Oil Certification Tests have been used for the past forty-five years to evaluate lubricant performance characteristics for valvetrain wear, viscosity increase, and piston deposit formation. Minimum performance standards for passenger car light duty gasoline engine oil categories are set by the International Lubricants Standardization and Approval Committee (ILSAC) (1) and the American Petroleum Institute (API) (2). This paper describes the development of the new ASTM Sequence IIIG Engine Oil Certification Test for use in evaluating the performance characteristics of engine oils meeting the next generation, low sulfur, low phosphorus, ILSAC GF-4 and API licensing requirements.

The ASTM Sequence VE test evaluates lubricant performance for controlling sludge deposits and minimizing overhead camshaft lobe wear. ILSAC asked JAMA to develop a new valve train wear replacement test since the Sequence VE test engine hardware will become obsolete in the year 2000. JAMA submitted the JASO specification M 328-951) KA24E valve train wear test. This first report presents the results of technical studies conducted when JASO M 328-95 was reviewed and the ASTM standardized version of the KA24E test (the Sequence IVA) was proposed. The cam wear mechanism was studied with the goal of improving reproducibility and repeatability. Engine torque was specified to stabilize the NOx concentration in blow-by, which improved test precision. Additionally, the specifications for induction air humidity and temperature, oil temperature control, and test fuel composition were modified when the ASTM version of the KA24E test was proposed.

The United States and Europe are mandating increasingly severe diesel fuel specifications, particularly with respect to sulfur content, and in some areas, aromatics content. This trend is directed towards reducing vehicle exhaust emissions and is generally beneficial to fuel quality, ignition ratings, and stability. However, laboratory studies, as well as recent field experience in Sweden and the United States, indicate a possible reduction in the ability of fuels to lubricate sliding components within the fuel injection system. These factors, combined with the trend toward increasing injection pressure in modern engine design, are likely to result in reduced durability and failure of the equipment to meet long-term emissions compliance. The U.S. Army Belvoir Fuels and Lubricants Research Facility (BFLRF) located at Southwest Research Institute (SwRI) developed an accelerated wear test that predicts the effects of fuel lubricity on injection system durability.

Emission performance of a late model vehicle equipped with an electrically-heated catalytic converter (EHC) system was evaluated after extended vehicle soak periods that ranged from 30 to 180 minutes. As soak periods lengthened, NMHC and CO emissions measured in hot transient driving cycles increased by 125 percent and 345 percent, respectively. These tests were baseline operations which had no resistance heating or secondary air injection to the converter system. Sources of increased NMHC and CO emissions as a function of vehicle soak time were both the converter system cool-down characteristics and engine restart calibration strategy. For soak periods of 30 and 60 minutes, EHC resistance heating without secondary air injection resulted in large improvements in NMHC and CO emission performance (i.e., 74 percent and 54 percent lower NMHC emissions versus no heat, no air operation after a 30- and 60-minute period, respectively).

Excessive wear and malfunctions in fluid power handling systems are often caused by contaminants or small particles that may be built-in, self-generated, or ingested from the environment. Filtration subsystems in such systems are designed to prevent these problems from happening. However, machine performance degradation, shortened service life, and even catastrophic failures are occasionally encountered in the real world. Then, what is the missing linkage? This paper tries to address the issue using a multi-disciplinary approach that employs failure analyses, laboratory experimentation, predictive correlation, and concurrent engineering with an emphasis on contaminant characterization and filtration strategies. Practical contamination analysis methodologies are discussed via examples and case studies.

The composition of natural gas delivered through the pipeline varies with time and location around the USA. These variations are known to affect engine performance and emissions through changes in fuel metering characteristics and knock resistance of the fuel. High output, low emissions natural gas engines are being developed that take advantage of the high knock resistance of natural gas. These optimized engines are operated close to knock-limited power where changes in fuel knock resistance can cause operational problems. Octane tests were conducted on natural gas blend fuels using a CFR octane rating engine. Two relationships between motor octane number and fuel composition were established. A correlation for motor octane number versus the reactive hydrogen-carbon ratio was developed, and octane weighting factors, which used the molar composition of the fuel to predict motor octane number, were also found.

This paper is the second of two that describe the effects of low-lubricity fuels on diesel injection pump performance. The first paper describes the primary failure mechanisms and wear processes in a number of failed pumps removed from both military and civilian vehicles that had been operated on Jet A-1 and diesel fuels. However, the multitude of unregulated parameters in practical operation renders quantitative comparison between different fuels and pump combinations impractical. This paper describes the degradation in pump performance and the wear processes associated with fuels of varying lubricity in the well-defined environment of a pump test stand. The test methodology concentrates on those areas previously demonstrated to be most susceptible to wear. The results indicate that pump durability is reduced by highly refined low-viscosity fuels, but may be successfully counteracted by either improved metallurgy or lubricity additives.

While standardized laboratory-scale wear tests are available to predict the lubricity of liquid fuels under ambient conditions, the reality is that many injection systems operate at elevated temperatures where fuel vaporization is too excessive to perform the measure satisfactorily. The present paper describes a High Pressure High Frequency Reciprocating Rig (HPHFRR) purposely designed to evaluate fuel lubricity in a pressurized environment at temperatures of up to 300°C. The remaining test parameters are identical to those of the widely standardized High Frequency Reciprocating Rig (HFRR). Results obtained using the HPHFRR indicate that wear rate with poor lubricity fuels is strongly sensitive to both temperature and oxygen partial pressure and may be orders of magnitude higher than at ambient conditions. Surprisingly however, wear rate was found to decrease dramatically at temperatures above 100°C, possibly due to evaporation of dissolved moisture.

Current industry trends in both powertrain electrification and vehicle drag reduction point towards reduced peak and average power demands from the internal combustion engine in future long-haul class 8 vehicles. Downsizing the engine displacement to match these new performance requirements can yield a benefit in drive cycle efficiency through reduced friction and improved cruise load efficiency. Downsizing by reducing cylinder count avoids the heat loss and friction penalties from reduced per-cylinder displacement and could allow a manufacturer to continue to leverage the highly optimized combustion system from existing heavy-duty engines in the new downsized offering. The concept of this study is to leverage powertrain electrification and the improvement trends in vehicle aerodynamics and rolling resistance to develop a fuel economy focused, downsized heavy duty diesel powertrain for future long-haul vehicles utilizing a reduced cylinder count.

The use of fuel additives is one possible approach to reduce wear and corrosion in methanol fueled automobile engines. One hundred and six compounds added to M100 fuel in modest concentrations (1%) were tested in a Ball on Cylinder Machine (BOCM) for their ability to improve lubricity. The most promising candidates were then tested in an engine using a modified ASTM Sequence V-D wear screening test. Additive performance was measured by comparing the buildup of wear metals in the oil to that obtained from an engine fueled with neat M100. The BOCM method of evaluating the additive candidates proved inadequate in predicting abrasive engine wear under the test conditions utilized for this research program.