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Conventional power steering systems can be “tailored” to provide light steering efforts for parking and low speed, or high steering efforts for stability and “road feel” at high speed. In either case, the customer's preferred steering efforts are not provided at all times. Compromises are required. The need for a speed-sensitive steering effort system has prompted the introduction of several innovative variable-assist steering systems in the past few years, which are currently used in some European and Japanese vehicles. This paper describes a Ford-patented variable-assist system used on the 1988 Lincoln Continental, the first application of vehicle speed-sensitive steering to an American-designed and manufactured vehicle. The Ford Variable-Assist Power Steering System is a “rotary steering valve” system. It uses a modification of the current rotary valve to provide low steering efforts (low torsion bar twist) at low speed and higher efforts (more twist) as vehicle speed increases.

“There's nothing new under the sun,” the old proverb says. But you only have to read a magazine, scan a periodical, listen to the radio, watch television, or glance at the multitude of ads that promise that such and such product is the latest trend or has up-to-date, state-of-the-art technology, to seemingly prove the old proverb wrong. However, old proverbs become old because they withstand the test of time. In this case, a hasty judgement should be withheld. Currently, as in the past, the above holds true for car radios as well. Whether in the United States, Europe, Canada or Latin America, the public has always been susceptible to last minute technological advances. It is curious then, that as far as car radio styling is concerned, their appearance has been typically rather conservative, and that it is only recently that styling has begun to change to be more in tune with the times.

The cyclic behavior of single overlap aluminum joints joined through a number of different methods has been investigated using Alcan 5754-O, an alloy that potentially could be used in structural applications. Overlap shear tests of spot welded, clinched and riveted joints are compared on the basis of their fatigue performance. The fatigue response of the spot welded joint was the baseline to which the other fasteners were compared. Test results showed an improvement of approximately 25% for both the mechanical clinch joints and aluminum rivets in fatigue strength at 106 cycles. The most significant improvement in fatigue strength of 100% was found for the self piercing rivets at 106 cycles. The failure behavior of the various joining methods is discussed as well as the surface appearance.

A cycle counting algorithm that will reduce a complex history into a series of discrete cycles is presented. The cycles determined by this technique are defined as closed stress-strain hysteresis loops of the type obtained from constant amplitude tests. Using the computer cycle counting algorithm, life predictions were made and compared with experimental results. These predictions were found to be typically within a ±3 factor of error. Also, the computer counting method was found to yield more accurate life predictions when compared to the histogram and range counting methods.

Vehicle sound quality has become an important basic performance requirement. Traditionally, automobile noise studies were focused on quietness. It is now necessary for the automobile to be more than quiet. The sound must be pleasing. This paper describes a development process to improve both vehicle noise level and sound quality. Formal experimental design techniques were utilized to quantify various hardware effects. A-weighted sound pressure level, Speech Intelligibility, and Composite Rating of Preference were the three descriptors used to characterize the vehicle's sound quality. Engineering knowledge augmented with graphical and statistical techniques were utilized during data analysis. The individual component contributions to each of the sound quality descriptors were also quantified in this study.

Although there was a safety awareness from the earliest days of the automobile, systematic approaches to designing for safety became more widespread after 1950 when large numbers of vehicles came into use in both the United States and Europe, and governments in both continents undertook a widespread highway development. Industry response to safety objectives and also to government regulation has produced a large number of safety enhancing engineering developments, including radial tires, disc brakes, anti-lock brakes, improved vehicle lighting systems, better highway sign support poles, padded instrument panels, better windshield retention systems, collapsible hood structures, accident sensitive fuel pump shut-off valves, and other items. A significant development was the design of the energy absorbing front structures.

In this paper, a soft computing approach to a model-free vehicle stability control (VSC) algorithm is presented. The objective is to create a fuzzy inference system (FIS) that is robust enough to operate in a multitude of vehicle conditions (load, tire wear, alignment), and road conditions while at the same time providing optimal vehicle stability by detecting and minimizing loss of traction. In this approach, an adaptive neuro-fuzzy inference system (ANFIS) is generated using previously collected data to train and optimize the performance of the fuzzy logic VSC algorithm. This paper outlines the FIS detection algorithm and its benefits over a model-based approach. The performance of the FIS-based VSC is evaluated via a co-simulation of MATLAB/Simulink and CarSim model of the vehicle under various road and load conditions. The results showed that the proposed algorithm is capable of accurately indicating unstable vehicle behavior for two different types of vehicles (SUV and Sedan).

A four-stroke, spark-ignition engine is described that seeks to achieve high expansion ratio and low throttling losses at light load, whilst retaining good knock resistance at full load operation and without the need for expensive mechanical changes to the engine. The engine does, however, incorporate a second inlet (transfer) valve and associated transfer port linked to the intake port. The timing of the transfer valve is different from that of the main inlet valve. Load modulation is achieved by control of the gas outflow from the transfer port. A computer model of the engine is first validated against measured data from a conventional engine. Comparisons are made of incylinder pressure at part load conditions, total air flowrate through the engine and intake port air velocities as a function of crank angle position.

There have been many articles published in the last decade or so concerning the components of an electronic stability control (ESC) system, as well as numerous statistical studies that attempt to predict the effectiveness of such systems relative to crash involvement. The literature however is free from papers that discuss how engineers might develop such systems in order to achieve desired steering, handling, and stability performance. This task is complicated by the fact that stability control systems are very complex and their designs and what they can do have changed considerably over the years. These systems also differ from manufacturer to manufacturer and from vehicle to vehicle in a given maker of automobiles. In terms of ESC hardware, differences can include all the components as well as the addition or absence of roll rate sensors or active steering gears to name a few.

This paper presents the application of a proposed fuzzy inference system as part of a stability control design scheme implemented with active steering actuator sets. The fuzzy inference system is used to detect the level of overseer/understeer at the high level and a speed-adaptive activation module determines whether an active front steering, active rear steering, or active 4 wheel steering is suited to improve vehicle handling stability. The resulting model-free system is capable of minimizing the amount of model calibration during the vehicle stability control development process as well as improving vehicle performance and stability over a wide range of vehicle and road conditions. A simulation study will be presented that evaluates the proposed scheme and compares the effectiveness of active front steer (AFS) and active rear steer (ARS) in enhancing the vehicle performance. Both time and frequency domain results are presented.

This paper presents a new transient passenger thermal comfort model. The model uses as inputs the vehicle environmental variables: air temperature, air velocity, relative humidity and mean radiant temperature all of which can vary as a function of time and space. The model also uses as inputs the clothing level and the initial physiological state of the body. The model then predicts as a function of time the physiological state of the body and an effective human thermal sensation response (e.g. cold, comfort, hot, etc.). The advantage of this model is that it can accurately predict the human thermal sensation response during transient vehicle warm-up and cooldown conditions. It also allows design engineers the ability to conduct parametric studies of climate control systems before hardware is available. Here we present the basis of the new thermal comfort model and its predictions for transient warm-up and cooldown conditions.

The pumping system used in a step ratio automatic transmission can consume up to 20% of the total power required to operate a typical automotive transmission through the EPA city cycle. As such, it represents an area manufacturers have focused their efforts towards in their quest to obtain improved transmission efficiency. This paper will discuss the history of automatic transmission pumps that develop up to 300 psi along with a description of the factors used to size pumps and establish pump flow requirements. The various types of pumps used in current automatic transmissions will be described with a discussion of their characteristics including a comparison based upon observations of their performance. Specific attention will be focused on comparing the volumetric efficiency, mechanical efficiency, overall efficiency, pumping torque and discharge flow.

This paper provides an overview of the dual EGO sensor method for OBD-II catalyst efficiency monitoring. The processes governing the relationship between catalyst oxygen storage, HC conversion efficiency, and rear EGO sensor response are reviewed in detail. A simple physical model relating catalyst oxygen storage capacity and rear EGO sensor response is constructed and used in conjunction with experimental data to provide additional insight into the operation of the catalyst monitor. The effect that the catalyst washcoat formulation has in determining the relationship between catalyst oxygen storage capacity and HC conversion efficiency and its impact on the catalyst monitor is also investigated. Lastly, the effects of catalyst failure mode, fuel sulfur, and the fuel additive MMT on the catalyst monitor's ability to properly diagnose catalyst function are discussed.

This paper begins with a comparison of the automotive power supply and loads in the early 1950's (near the end of the six-volt era) to the modern counterpart in the early 1990's (possibly near the end of the 12-volt era). A typical power supply specification sheet is developed based on the in-vehicle performance characteristics. From this summary, two attributes are noted: first, the system voltage is not very stable and second, transient protection is limited. With this awareness and the knowledge that the power supply of the future will need architectural change, a review of the design assumptions using a total system view and a long term outlook is advanced. Using a rule based design process and employing available technology to enhance the power system architecture, a number of elements are proposed for consideration in new designs.

The present work discusses an objective test and analysis method developed to quickly quantify steering gear rattle noise heard in a vehicle. Utilizing envelope analysis on the time history data of the rattle signal, the resulting method is simple, fast, practical and yields a single-valued metric which correlates well to subjective measures of rattle noise. In contrast to many other rattle analysis methods, the approach discussed here is completed in the time domain. As applied to rattle noise produced by automotive electric steering systems, the metric produced with this analysis method correlates well with subjective appraisals of vehicle-level rattle noise performance. Lastly, this method can also be extended to rattle measurements at the component and subcomponent level.

Ribbed floor panels have been widely applied in vehicle body structures to reduce interior noise. The conventional approach to evaluate ribbed floor panel designs is to compare natural frequencies and local stiffness. However, this approach may not result in the desired outcome of the reduction in radiated noise. Designing a “quiet” floor panel requires minimizing the total radiated noise resulting from vibration of the floor panel. In this study, the objective of ribbed floor panel design is to reduce the total radiated sound power by optimizing the rib patterns. A parametric study was conducted first to understand the effects of rib design parameters such as rib height, width, orientation, and density. Next, a finite element model of a simplified body structure with ribbed floor panel was built and analyzed. The structural vibration profile was generated using MSCINastran, and integrated with the acoustic boundary element model.

In this paper we describe the application of optimization techniques to the design of valvetrains in high revving internal combustion engines. The methods presented are based on parameter optimization [1] and the minimum principle by Pontrjagin [2] and will be applied to cam lobe and valve spring optimization, aiming at reducing oscillation amplitudes and improving control of the valvetrain over a broad speed range. To put the task of optimization into context the engineering requirements for valvetrains and methods to allow their computer based analysis are described. Furthermore principle considerations for valve event curve generation and parametrization, and on optimization techniques are discussed. Based on these fundamentals, optimization aims and constraints are formulated. Furthermore different examples of the application of automated optimization are presented in the area of cam profile optimization and valve spring optimization.

The long term visual appearance of exterior chrome-plated parts is highly dependent on part design and supplier performance. The use of numerous complex designs coupled with the pressures of competition has caused a statistically high percentage of parts to be manufactured which do not fully meet customer expectations. A coordinated approach to improve supplier performance and simplification of part designs was required. A task force was established to address these issues in 1980 and desirable results were achieved.

The thermal comfort of passengers within a vehicle is often the main objective for the climate control engineer; however, the need to maintain adequate visibility through the front and side windows of a vehicle is a critical aspect of safe driving. This paper compares the performance of the side window defrosting and demisting mechanism of several current model vehicles. The study highlights the drawbacks of current designs and points the way to improved passive defrosting mechanisms. The investigation is experimental and computational. The experiments are carried out using full-scale current vehicle models. The computational study, which is validated by the experiments, is used to perform parametric investigation into the side window defrosters performance. The results show that the current designs of the side-defroster nozzles give maximum airflow rates in the vicinity of the lower part of the window, which yields unsatisfactory visibility.

This paper presents a Computational Fluid Dynamic(CFD) model for the oil pump simulations aimed at better understanding the flow characteristics for improving their designs and reducing product development cycles. Several advanced numerical technologies have been developed to handle the complex geometries of oil pumps and the moving interfaces between the rotating and stationary parts. Two basic oil pump configurations, a vane oil pump and a gerotor oil pump, have been studied with the present method. The numerical results are compared with the existing experimental data.