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This paper describes a newly developed steel composition and surface modification methods for improving the rolling contact fatigue strength of parts used in transmission systems, especially continuously variable transmissions (CVTs) to increase their torque capacity. The mechanisms of two types of typical rolling contact fatigue phenomenon in case hardening steel were examined with the aim of improving rolling contact fatigue strength. One concerned white etching constituents (WEC) and the other one concerned peculiar microstructural changes caused by hydrogen originating from decomposition of the lubrication oil as a result of repeated rolling contact stress cycles. The rolling contact fatigue strength limit due to WEC has been improved markedly by dispersing fine M23C6 alloy carbides in the martensite matrix at the subsurface layer of parts.

In automotive engines, the cylinder head and cylinder block are geometrically complex in that they have a large number of three-dimensional blends and fillets. In operation these components will experience a large number of stress concentrations with inherently large stress gradients. In an effort to provide a more accurate prediction of the propensity of a stress concentration in a cylinder head or cylinder block to develop a fatigue crack, herein a methodology is presented for adjusting the fatigue strength of the given material based upon the relative ‘size’ of the stress concentration. For a given linear-elastic stress history, a normal-stress based critical-plane method is used to first determine the predicted plane for crack initiation and growth. On this plane, the χ% stressed-area is defined as the material area that experiences χ% of the peak normal stress.

A new method for improving the fatigue lives of holes in metal structures has been developed. The StressWave® process provides compressive residual stresses and fatigue life improvement factors that are similar to or exceed those produced by legacy mandrel cold working processes. StressWave creates the stresses prior to machining the hole, without any pre- or extra post-processing operations. The process has been applied in a variety of alloys (aluminum, steel, titanium and cast iron) and section thickness (0.8 to 25 mm). Fatigue testing has shown life improvement factors typically five to twenty times greater than untreated open-hole specimens. Residual stress distributions have been measured by neutron diffraction and photo-elastic techniques and compared with FEA analysis to verify process parameters. Crack growth measurements and fractography have revealed the beneficial compressive residual stresses extend fatigue crack growth life.

In order to simulate the crack connection between cords and the inter-ply crack growth in the belt-layer of a real TBR (Truck and Bus Radial) tire, we tested two-ply rubber-cord laminate specimens with exposed edges in constant displacement control. We evaluated measurement of the crack connection when crack reaches the half of the length between 45° aligned cords, and measured the amount of the crack growth by the steel probe method. We then performed a two-dimensional analysis of the crack connection between cords at the exposed edges. The theoretical life of the specimens from the crack connection life between cords (the critical value) and from this critical value to the final failure can thus be calculated by the used of tearing energy. The theoretical life was compared with those of the experimental life. The life prediction up to the critical value has an error of 20% compared to experimental life, and up to the final failure about 65% error.

The paper reports the research activity related to the development of a twin-spark SI engine equipped with a variable valve timing (VVT) device. Improvements on the fuel consumption at part load are expected when an high internal exhaust gas recirculation (internal EGR) level is realized with a proper phasing of the VVT device. The twin-spark solution is implemented to improve the burning speed at low load, and to increase the EGR tolerance levels. Both experimental and theoretical analyses are carried out to investigate the real advantages of the proposed engine architecture. In particular an original quasi-dimensional model for the simulation of the burning process in a twin-spark engine is presented. The model is mainly utilized to find the proper combination of VVT device position (and hence EGR level) and spark advance for different engine operating conditions. A comparison with the single-spark solution is also provided.

A transient knock prediction technique has been developed by coupling a zero-dimensional knocking simulation with chemical kinetics and a one-dimensional gas exchange engine model to study the occurrence of transient knock in SI engines. A mixed chemical reaction mechanism of the primary reference fuels was implemented in the two-zone combustion chamber model as the auto-ignition model of the end-gas. An empirical correlation between end-gas auto-ignition and knock intensity obtained through intensive analysis of experimental data has been applied to the knocking simulation with the aim of obtaining better prediction accuracy. The results of calculations made under various engine operating parameters show good agreement with experimental data for trace knock sensitivity to spark advance.

When the exhaust valve of a conventional spark ignition engine opens at the end of the expansion stroke, a large quantity of high pressure exhaust gas is freed to the atmosphere, without using its availability. An engine that could use this lost energy should have a better efficiency. The equations for an over-expanded cycle (Miller cycle) are developed in this paper, together with equations for the Otto cycle, diesel cycle and dual cycle, all at part load, so they can be compared. Furthermore, indicated cycle thermodynamical comparisons of a S.I. engine at part load (Otto cycle at half load), a S.I. engine at WOT (with half displacement) and two over-expanded S.I. engines (with different compression strokes) are examined and compared, with the aim of extending the referred theoretical cycle comparisons.

Results are presented from a brief validation study on software which was written to simulate one-dimensional unsteady state transport of gaseous fuel mixtures through the intake manifold of a multi-cylinder, homogeneous charge spark ignition engine, and which also models in-cylinder thermodynamic and fluid flow processes, flame propagation, combustion and emissions formation. The focus of this paper is on the transport of pure hydrogen through the intake manifold of a 1.6 liter engine during the transition from steady state motoring to fired operation, at excess air ratios of 1.8 and 2.35. Indirect verification of hydrogen transport characteristics was determined by comparing measured and predicted IMEP's for different cylinders during the period immediately after hydrogen fuelling commenced.

Fatigue life regression models with constant and non-constant variance are evaluated and compared with a Random Fatigue Limit Model and a Probit model to estimate the fatigue strength and S-N relationship from fatigue test data. The Maximum Likelihood method is used to estimate parameters of the above models. Emphasis also is given to assessing the variation in fatigue strength and S-N relationships estimated from different models. Two different test data sets are selected for the evaluations: (1) a full S-N test data set with a large range of stresses and (2) a staircase test data set with a characteristically more narrow range of stresses. Model adequacies are evaluated from residuals and Anderson Darling measures of their fits. The Random Fatigue Limit Model is observed to best fit the test data, but its large number of parameters are under constrained with staircase test data and require care to get good results.

Temperature fluctuations in the turbulent flow-field inside an engine's cylinder are important because they enhance the rates of the NO forming reactions. This work presents a zero-dimensional model for the root mean square (r.m.s) temperature fluctuations in a spark ignition engine. A thermodynamic combustion model is used to compute the NO formation rates after accounting for the effect of temperature fluctuations on the reaction rates. The computed tailpipe Zeldovich NO emissions may be up to 25 % higher because of the inclusion of the effect of the temperature fluctuations. It may also be necessary to add the contribution of prompt NO and the turbulent N2O mechanism to the turbulent Zeldovich NO so as to match the experimentally observed values under lean conditions.

During last four years the authors were involved in the simulation and investigation of combustion and ionization in the cylinder of gasoline and natural gas Spark Ignition (SI) engine. Two-zone model of combustion and chemical non-equilibrium ionization and results of the numerous numerical investigation were presented by the authors at SAE 2002 and SAE 2003 World Congresses. This model and numerical results provided an important insight into combustion products behavior and gave the chance to find correlation between chemical and thermal ionization of combustion products and SI engine performances. In order to provide better correspondence of the numerical data to the experimental results in the wide range of operational parameters for different geometry of engines a new three-zone model was developed and successfully tested.

The increase in number of automobiles due to its convenience brought serious increases in environmental load. The rate of attainment of environmental standards for nitrogen dioxide (NO2) and suspended particulate matter (SPM) in urban areas is still low in Japan. Diesel vehicles emit the vast majority of air pollutants from exhaust. Therefore, developing emission measures, particularly for diesel vehicles, is an urgent task for addressing air pollution. Furthermore, at the Third Conference of the Parties to the UN Framework Convention on Climate Change (COP 3) held in Kyoto in December 1997, Japan pledged to reduce greenhouse gas emissions to 6 percent below 1990 levels for the first commitment period of 2008 to 2012. To address vehicle emissions, Japan is gradually introducing increasingly strict NOx and particulate matter regulations.

Natural gas (methane) fueled engines are a new technology which can produce power as well as synthesis gas. The power from the engine is useful in a variety of direct drive systems, i.e. HVAC or stationary generators. However, its application should be limited to non-mobile applications because of the extra systems necessary to capture and separate the hydrogen. The hydrogen obtained from the system can then be used to power fuel cells for a direct electro-chemical process, or to enrich other fuels in other internal combustion engines. In this report, the operating conditions of the methane fueled modified compression ignition engine are subjected to some narrow band parametric investigation. The temperature and pressure distributions and species concentrations are reported. Engine performance data including air-fuel ratio, thermal efficiency, indicated specific fuel consumption and gross indicated power are calculated.

The goal of the Clean Engine Vehicle project (CEV) was the conversion of a gasoline engine to dedicated natural gas operation in order to achieve a significant reduction in CO2 emissions. The targeted reduction was 30% compared with a gasoline vehicle with similar performance. Along with the reduction in emissions, the second major requirement of the project, however, was compliance of the results with Euro-4 and SULEV emission limits. The project entailed modifications to the engine and the pre-existing model-based engine control system, the introduction of an enhanced catalytic converter and downsizing and turbocharging of the engine. As required by the initiators of the project, all components used were commonly available, some of them just being optimized or modified for natural gas operation.

While most reductions in diesel particulate matter (PM) have been implemented through internal engine improvements and aftertreatment systems, additional reductions may be found by controlling intake contaminants. Under the ideal conditions of operating with ultra low sulfur diesel fuel and filtered and conditioned intake air, a diesel engine produces a certain amount of PM. The PM emission levels may increase when intake air is polluted during harsh on- or off-road conditions. In this study, contaminants were allowed to enter the intake tract of the engine to determine whether or not increased particle ingestion leads to increased particulate matter expulsion. Diesel and test dust contaminants dispersed in intake air were filtered using both a conventional filtering medium and a nano-medium to determine their effects on diesel engine-out PM emissions. The paper characterizes the two media by microstructure, permeability, porosity, and fractional efficiency.

As the interest in global environmental protection increases, so do the worldwide social requirements of annually decreasing fuel consumption and producing cleaner exhaust gas. In California, a new special category of emissions standard, PZEV was implemented, as the most stringent emissions standard in the world. To meet this standard, it is crucial to decrease exhaust gas unburned hydrocarbon emissions, especially in cold start conditions. Toyota has sought a new approach to decrease these emissions and developed the Toyota Coolant Heat Storage System (CHSS). This system recovers hot engine coolant, in a heat-insulated reservoir, used for the next cold start, during and / or after engine operation and stores it in a reservoir during the engine-off soak period.

In September 2003, the Mercedes Car Group set another milestone by introducing the fifth generation of automatic transmissions developed and manufactured in-house since 1960. The world's first 7-speed automatic transmission 7G-TRONIC is featured in the Mercedes-Benz S, SL, CL and E-Classes with V8 gasoline engines. Deduced from the demands of the requirement specifications, the 5-speed automatic transmission was decisively improved; the result is a clear increase in spontaneity, agility, fuel economy, and driving comfort for the customer. And because of the harmony between the vehicle and its powertrain, excellent results in the areas of performance, reduced emissions, comfort, and acoustics are obtained.

Compressed Natural Gas (CNG)/diesel Dual Fuel Engine(DFE) was one of the best choices for solving energy crisis and environment pollution. In order to study and improve the emission performance of the CNG/diesel DFE, an emission model by means of Radial Basis Function neural network was established. The model identified as a black box model with input-output training data didn't require priori knowledge. There were 100 group experimental data over the operation conditions from low load and low rotate speed to heavy load and high rotate speed using for training the neural network, and 20 group test data using for verifying the model. The study results showed that the predicted results were good agreement with the experimental data. This proves that the developed emission model can be used to successfully predict and optimize the emission performance of DFE.

Spiraling manufacturing costs for exhaust-gas treatment and tougher legislative requirements are good reasons for seeking new approaches to reach the ever-increasing emission-targets. Because of the strong correlation between technical feasibility and related costs, it is necessary not only to reach engineering targets but also achieve them at an acceptable cost. One decisive step in this regard is the so-called ‘Exhaust-Gas Management (EGM)’ strategy. The basic idea of EGM is an integrated optimization process of the complete engine periphery by evaluating the technical benefit and its cost. In the past the OEM has carried out this job as a rule, but a new form of EGM has since been defined through direct collaboration between engine periphery suppliers. In this paper the details of the new form of EGM and its benefits will be presented. This includes the steps involved in modifying the exhaust system and catalytic converter design, new ECU functions and calibration strategies.

The present work investigated the real-world emission performance of a typical light-duty gasoline vehicle to identify the most significant vehicle operating parameter responsible for excessive real-world emission levels. Based upon tailpipe-out emission levels two distinct portions in the engine maps could be identified; a clean portion of the map, which covers the engine operating points within the European the legislative drive cycle, and an unclean portion of the map that is outside the legislative testing. A systematic investigation of the tailpipe-out emission levels for the real-world drive cycle showed that the levels of vehicle speed and acceleration are immaterial if the vehicle operating points remain within the cleaner zone of the engine map. The methodical approach followed to identify the most significant vehicle operating parameter responsible for the real-world emission levels is given in this paper.