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In this paper a design methodology for automotive heat exchangers has been applied which brings robustness into the design process and helps to optimize the design goals: as to maintain an optimal coolant temperature and to limit the vehicle underhood air temperature within a tolerable limit. The most influential design factors for the heat exchangers which affect the goals have been identified with that process. The paper summarizes the optimization steps necessary to meet the optimal functional goals for the vehicle as mentioned above. Taguchi's [1] Design for Six Sigma (DFSS) methods have been employed to conduct this analysis in a robust way.

Proposed LEV-III emission level will require improvements in NMOG, CO and NOx emissions as measured over FTP and US06 emission cycles. Incremental improvements in washcoat technologies, cold start calibration and catalyst system design are required to develop a cost effective solution set. New catalyst technologies demonstrated both lower HC and NOx emissions with 25% less platinum group metals (PGM). FTP and US06 emissions were measured on a 4-cylinder 2.4L application which compares a close-coupled converter and close-coupled + underfloor converter systems. A PGM placement study was performed with the close-coupled converter system employing these new catalyst technologies. Emissions results suggest that the placement of PGM is critical in minimizing emissions and PGM costs.

This paper studies the effects of various types of parking brake cable construction on parking brake system efficiency. Testing was conducted on a variety of common cable constructions from several industry sources. Cable construction variables include different types of conduit and wire strand. Input travel, input force, output travel, and output force were carefully measured under controlled conditions. Force, travel and hence work efficiencies were calculated and analyzed to identify any differences that might exist under the defined test conditions. Conclusions were drawn that might provide direction for improving parking brake system designs that have performance issues caused by poor cable efficiency.

The fuel air ratio imbalance between individual cylinders can result in poor fuel economy and severe exhaust emissions. Individual cylinder fuel air ratio control is one of the important techniques used to improve fuel economy and reduce exhaust emission. California Air Resources Board (CARB) also has required automotive manufacturers to equip with on-board diagnosis system for cylinder fuel air ratio imbalance detection starting in 2011. However, one of the most challenging tasks for the individual cylinder fuel air ratio control and cylinder imbalance diagnosis is how to retrieve the cylinder fuel air ratio information effectively at low cost. This paper presents a novel and practical signal processing based fuel air ratio estimation method for individual cylinder fuel air ratio balance control and on-board fuel air ratio imbalance diagnosis.

Due to the multitude of external design constraints, such as increasing fuel economy standards, and the increasing number of global vehicle programs, developers of automotive transmission controls have to cope with increasing levels of powertrain system complexity. Achieving these requirements while improving system quality, reducing development cost and improving time to market is a very challenging task. To achieve this goal, a rapid prototype controller was used to develop a new transmission clutch temperature model. This model is used to detect clutch surface overheating, improve design and enhance shift quality.

Time-temperature analysis methods are usually applied to predict the useful life of automotive components. Components life is affected by exposure to heat during vehicle service life. The extent of reduction in component life, which may be caused by material thermal degradation, depends on the component temperature and the time duration at that temperature. The rate of material thermal degradation of automotive components varies widely depending on material thermal stability, vehicle duty cycle, and the thermal environment that the component is exposed to. Thermodynamic properties such as the activation energy of each material are used to determine the rate of thermal degradation [1,2]. In this approach, material thermal degradation models are used to predict component life during the service life of a vehicle. As the rate of thermal degradation increases with increasing material temperature, the useful life of a component will be reduced as the material temperature increases.

In this paper, a transient thermal analysis model for Diesel fuel systems is presented. The purpose of this work is to determine the fuel temperature at various locations along the system, especially inside the tank and at the returned fuel inlet to the tank. Due to the fact that the fuel level is continuously changing during any driving condition, the fuel mass inside the tank is also continuously changing. Consequently, the fuel temperature will change even under steady driving or idle conditions, therefore, this problem should be analyzed using transient thermal analysis models. Effective thermal management requires controlling the surface temperature of the fuel tank, fuel lines and the fuel temperature at the fuel return line as well as inside the tank [1, 2]. Based on the thermal analysis results, it is possible to determine the major source of heat input at several locations of the fuel system.

Carburized parts often see use in powertrain components for the automotive industry. These parts are commonly quenched and tempered after the carburizing process. The present study compared the austempering heat treatment to the traditional quench-and-temper process for carburized parts. Samples were produced from SAE 8620, 4320, and 8822 steels and heat treated across a range of conditions for austempering and for quench-and-tempering. Distortion was examined through the use of Navy C-Ring samples. Microstructure, hardness, and Charpy toughness were also examined. X-ray diffraction was used to compare the residual stress found in the case of the components after the quench-and-temper and the austempering heat treatments. Austempering samples showed less distortion and higher compressive residual stresses, while maintaining comparable hardness values in both case and core. Toughness measurements were also comparable between both processes.

Two on-line algorithms have been developed to acquire driveline component loads in terms of revolutions at torque and rainflow cycle counting matrix. These algorithms have been implemented in real-time on a standard engine controller unit and have been optimized for fast run-time and low memory requirements. The revolutions at torque algorithm is intended to count the number of driveshaft revolutions in each torque level for each gear and store the number of counts in the engine controller memory. The rainflow cycle counting algorithm is intended to count driveshaft torque cycles and to store the number of counts in a two dimensional “from-to” matrix format in the engine controller memory. The revolutions at torque histogram data and the rainflow cycle counting matrix are then downloaded from the vehicle using the data collection device. Download occurs when the vehicle is serviced at a dealership.

In today's light-weight vehicles, the strength of spot welds plays an important role in overall product integrity, reliability and customer satisfaction. Naturally, there is a need for a quick and reliable technique to inspect the quality of the welds. In the past, the primary quality control tests for detecting weld defects are the destructive chisel test and peel test [1]. The non-destructive evaluation (NDE) method currently used in industry is based on ultrasonic inspection [2, 3, 4]. The technique is not always successful in evaluating the nugget size, nor is it effective in detecting the so-called “cold” or “stick” welds. Therefore, it is necessary to develop a precise and reliable noncontact NDE method for spot welds. There have been numerous studies in predicting the weld nugget size by considering the spot-weld process [5, 6].

During the vehicle development process, dimensional variation simulation modeling has been applied extensively to estimate the effects of build variation on the final product. Traditional variation simulation methods analyze the tolerance inputs of structural components, but do not account for any compliance effects due to stiffness variation in tuning components, such as bushings, springs, isolators, etc., since both product and process variation are simulated based on rigid-body assumptions. Vehicle performance objectives such as ride and handling (R&H) often involve these compliance metrics. The objective of this paper is to present a method to concurrently simulate the tolerance from the structural parts as well as the variability of compliance from the tuning components through an integration package. The combination of these two highly influential effects will allow for a more accurate prediction and assessment of vehicle performance.

Valve ticking noises within a cam actuated valve train can arise mysteriously. One valve train may produce valve ticking noises, while a second, geometrically similar valve train may perform more quietly. To better understand this phenomena, we examine in detail the prototypical motion of a valve driven by a rocker arm with cylindrical rocker pad. General features of a valve's motion through its guide, induced by a rocker arm with a cylindrical pad, are derived. From these general features of valve motion, guide contact points during lift events can be inferred, and as a result, detailed forces and moments acting on the valve may be derived. From this derivation of forces acting on the valve, a metric for assessing the propensity of a valve train to tick as a result of the valve stem impacting its guide is proposed. The proposed metric indicates how the likelihood of valve tick noise can be reduced through judicious choices for valve train geometries, clearances and surface finishes.

Physical modeling has been used by the industry to improve development time and produce a quality product. In this paper, we will describe two methods used in system control to take advantage of the physical model. One method describes a complete transmission physical model with a full system control utilizing co-simulation techniques. Data will be presented, and comparison to vehicle data will be conducted and verified. The second method will illustrate how to utilize the physical model to improve system design and modification. In this method, vehicle data will be used as inputs to the model, the model output will be verified against vehicle output data. The two methods are excellent tools for the Design For Six Sigma process (DFSS design).

Environmental concerns and government regulations are factors that have led to an increased focus on fuel economy in the automotive industry. This paper identifies a method used to improve the efficiency of a front-wheel-drive (FWD) automatic transmission. In order to create improvements in large complex systems, it is key to have a large scope, to include as much of the system as possible. The approach taken in this work was to use Design for Six Sigma (DFSS) methodology. This was done to optimize as many of the front-wheel-drive transmission components as possible to increase robustness and efficiency. A focus of robustness, or consistency in torque transformation, is as important as the value of efficiency itself, because of the huge range of usage conditions. Therefore, it was necessary to find a solution of the best transmission component settings that would not depend on specific usage conditions such as temperatures, system pressures, or gear ratio.

Meeting regulated tailpipe emission standards requires a full system approach by automotive engineers encompassing: engine design, combustion system metrics, exhaust heat management, aftertreatment design and exhaust system packaging. Engine and combustion system design targets define desired engine out exhaust constituents, exhaust gas temperatures and oil consumption rates. Protecting required catalytic converter volume in the engine bay for stricter tailpipe emission standards is becoming more difficult. Future fuel economy mandates are leading to vehicle downsizing which is affecting all aspects of vehicle component packaging. In this study, we set out to determine the potential palladium (Pd) cost penalty as a result of increased light-off time required as a catalyst is positioned further away from the engine. Two aged converter systems with different Pd loadings were considered, and EPA FTP-75 emission tested at six different catalyst positions.

Establishing data adjustments that will give an interference free result for bluff bodies in automotive wind tunnels has been pursued for at least the last 45 years. Recently, the Two-Measurement correction method that yields a wake distortion adjustment for open jet wind tunnels has shown promise of being able to adjust for many of the effects of non-ideal static pressure gradients on bluff automotive bodies. Utilization of this adjustment has shown that a consistent drag results when the vehicle is subjected to the various gradients generated in open jet wind tunnels. What has been lacking is whether this consistent result is independent of the other tunnel interference effects. The studies presented here are intended to fill that gap on the performance of the two-measurement technique. The subject CFD studies are designed to eliminate all wind tunnel interference effects except for the variation of the (linear) static pressure gradient.

This paper presents a process for the selection of spring rate and pre-load for an adaptively controlled pivoting vane oil pump. The pivoting vane pump has two modes: high and low speed. A spring within the pump is installed to induce a torque that causes an adaptive displacement mechanism within the pump to move toward maximum oil chamber size. In low speed mode, two feedback regions are pressurized that produce torques that counter the spring generated torque. Together, both regions being pressurized by main oil gallery pressure tend to reduce pump displacement more at lower speeds than if only a single chamber is pressurized. At higher speeds, a solenoid switch turns off pressure to one of the feedback pressure chambers, thereby reducing feedback torque that counters spring torque. This enables higher pressure calibrations in this speed mode. In this paper, we identify a process for choosing the spring rate and pre-load that calibrates the adaptive displacement mechanism.

To meet the 2010 diesel engine emission regulations, an aftertreatment system was developed to reduce HC, CO, NOx and soot. In NOx reduction, a baseline SCR module was designed to include urea injector, mixing decomposition tube and SCR catalysts. However, it was found that the baseline decomposition tube had unacceptable urea mixing performance and severe deposit issues largely because of poor hardware design. The purpose of this article is to describe necessary development work to improve the baseline system to achieve desired mixing targets. To this end, an emissions Flow Lab and computational fluid dynamics were used as the main tools to evaluate urea mixing solutions. Given the complicated urea spray transport and limited packaging space, intensive efforts were taken to develop pre-injector pipe geometry, post-injector cone geometry, single mixer design modifications, and dual mixer design options.

A set of reduced chemical mechanisms was developed for use in multi-dimensional engine simulations of premixed gasoline combustion. The detailed Primary Reference Fuel (PRF) mechanism (1034 species, 4236 reactions) from Lawrence Livermore National Laboratory (LLNL) was employed as the starting mechanism. The detailed mechanism, referred to here as LLNL-PRF, was reduced using a technique known as Parallel Direct Relation Graph with Error Propagation and Sensitivity Analysis. This technique allows for efficient mechanism reduction by parallelizing the ignition delay calculations used in the reduction process. The reduction was performed for a temperature range of 800 to 1500 K and equivalence ratios of 0.5 to 1.5. The pressure range of interest was 0.75 bar to 40 bar, as dictated by the wide range in spark timing cylinder pressures for the various cases. In order to keep the mechanisms relatively small, two reductions were performed.

Using gasoline and diesel simultaneously in a dual-fuel combustion system has shown effective benefits in terms of both brake thermal efficiency and exhaust emissions. In this study, the dual-fuel approach is applied to a light-duty spark ignition (SI) gasoline direct injection (GDI) engine. Three combustion modes are proposed based on the engine load, diesel micro-pilot (DMP) combustion at high load, SI combustion at low load, and diesel assisted spark-ignition (DASI) combustion in the transition zone. Major focus is put on the DMP mode, where the diesel fuel acts as an enhancer for ignition and combustion of the mixture of gasoline, air, and recirculated exhaust gas. Computational fluid dynamics (CFD) is used to simulate the dual-fuel combustion with the final goal of supporting the comprehensive optimization of the main engine parameters.