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CFD (Computational Fluid Dynamics) has been used to analyze vehicle air flow. In cross wind conditions an asymmetrical flow field around the vehicle is present. Under these circumstances, in addition to the forces present with symmetric air flow (drag and lift forces and pitching moment), side forces and moments (rolling and yawing) occur. Issues related to fuel economy, driveability, sealing effects (caused by suction exerted on the door), structural integrity (sun roof, spoiler), water management (rain deposit), and dirt deposit (shear stress) have been investigated. Due to the software developments and computer hardware improvements, results can be obtained within a reasonable time frame with excellent accuracy (both geometry and analytical solution). The flow velocity, streamlines, pressure field, and component forces can be extracted from the analysis results through visualization to identify potential improvement areas.

THIS paper describes what the authors consider to be a simplified method of determining the vapor-locking tendencies of gasolines. The study of vapor lock was undertaken after they found the Reid vapor pressure method to be inadequate. The result of their work was the development of the General Motors vapor pressure, a single number which predicts vapor-locking tendency. The authors point out the following advantages of the new method: It allows direct comparisons of vapor-lock test results of different reference fuel systems; establishes distribution curves of volatility requirements of cars for vapor-lock free operation and of vapor-locking tendencies of gasolines; is a common reference value for both petroleum and automotive engineers. Finally, it more realistically evaluates the effects of small weathering losses on vapor-locking tendency than does Rvp.

Today trucks account for close to half of the US passenger vehicle market. And customers expect more and more from their trucks in terms of comfort and convenience features. The key to developing Best-in-Class comfort and convenience attributes lies in applying Ergonomic principles to the vehicle interior design. Lear Corporation has recently studied 4 truck interiors in the Sport Utility Market Segment focusing on Ergonomic design issues. This paper will review the Sport Utility study results and make interior design recommendations. In this market, functionality is of primary importance to customers. Using random samples of truck owners, we have examined the functionality of door panels, consoles, controls, cupholders, cargo covers and the rear cargo area. Several factors ranging from reach criteria, tactile feel and usability through operating efforts and the motion required to operate the various features were examined.

The purpose of this paper is to illustrate the use of Taguchi experimental methods as a development tool for designing a manufacturing process for inner door panels. Through analysis of experimental results, it was possible to identify critical manufacturing variables, as well as demonstrate inherent process capability.

Extending engine-oil-change intervals is of interest from the standpoint of reducing used oil disposal and reducing time and expense of maintenance. However, the oil must be changed before serious oil degradation and engine damage occur. Three variables which influence oil degradation were chosen for investigation: base oil composition (synthetic oil versus mineral oil), trip length (short trips versus long trips), and driving schedule (degrading an oil during a given type of service, then changing to another type of service without an intervening oil change). Analysis of oil samples taken throughout the testing program indicated that type of service (freeway compared to short trip) influenced oil degradation to a greater extent than oil type. That is, API SG-quality synthetic oil in short-trip service degraded faster than borderline SG-quality mineral oil in long-trip service.

In recent years, the perceived quality of powered seat adjusters based on their sound during operation has become a primary concern for vehicle and seat manufacturers. Historical noise targets based on overall dB(A) at the occupant's ear have consistently proved inadequate as a measure of the sound quality of a seat adjuster. Significant effort has been devoted to develop alternative sound quality metrics that can truly discriminate between “good” and “bad” seat adjusters. These new metrics have been successfully applied for some years by product development engineers in test labs. However, in the assembly plant the sound quality of the seat adjuster is still assessed subjectively by an operator at the end of the assembly line. The main problem with this approach is not only the lack of consistency and repeatability across large samples of seat tracks, but also the fact that the only feedback provided from the end-of-line to the product development team is of subjective nature.

Aqua-ammonia absorption refrigeration cycle and R-134a Vapor jet-ejector refrigeration cycle for automotive air-conditioning were studied and analyzed. Thermally activated refrigeration cycles would utilize combustion engine exhaust gas or engine coolant to supply heat to the generator. For the absorption system, the thermodynamic cycle was analyzed and pressures, temperatures, concentrations, enthalpies, and mass flow rates at every point were computed based on input parameters simulate practical operating conditions of vehicles. Then, heat addition to the generator, heat removal rates from absorber, condenser, and rectifying unit, and total rejection heat transfer area were all calculated. For the jet-ejector system, the optimum ejector vapor mass ratio based on similar input parameters was found by solving diffuser's conservation equations of continuity, momentum, energy, and flow through primary ejector nozzle simultaneously.

THIS paper describes the springs, control system, and ride of the air suspension system on the 1958 Buick. The system is a semiclosed one, providing a variable-rate suspension, automatic leveling and trim control, and manual lift. The latter feature is a knob below the instrument panel which can be operated when necessary to cope with unusual clearance conditions. The car remains at the same height with loads of up to five passengers and 500 lb in the trunk. The authors describe the road-holding ability of a car with this suspension system as excellent.

In this paper the application of Statistical Energy Analysis (SEA) to the sound package design for a fuel cell powered sedan is presented. Fuel cell vehicles represent a different challenge to a vehicle with a conventional powertrain. With the replacement of the internal combustion engine (ICE), a principal source of airborne and structure-borne powertrain noise, the expectation is that the cabin noise levels would be significantly reduced as the main noise sources would be road and wind noise. A fuel cell powertrain, however, has a number of mechanical sources on the body structure that will radiate airborne noise and may transmit significant structure-borne noise to the vehicle interior. With this alternative power train, much of the conventional wisdom on vehicle sound package developed from experience with ICE's must be reconsidered.

This paper describes the application of Statistical Energy Analysis (SEA) and Experimental SEA (ESEA) to calculating the transmission of air-borne and structure-borne noise in a mid-sized sedan. SEA can be applied rapidly in the early stages of vehicle design where the degree of geometric detail is relatively low. It is well suited to the analysis of multiple paths of vibrational energy flow from multiple sources into the passenger compartment at mid to high frequencies. However, the application of SEA is made difficult by the geometry of the vehicle's subsystems and joints. Experience with current unibody vehicles leads to distinct modeling strategies for the various frequency ranges in which airborne or structure-borne noise predominates. The theory and application of ESEA to structure-borne noise is discussed. ESEA yields loss factors and input powers which are combined with an analytical SEA model to yield a single hybrid model.

Seats and carpets were evaluated for generating static charges on vehicle occupants. Active measures that eliminate or reduce static accumulation, and passive measures that dissipate static charge in a controlled manner were investigated. The active measures include using durable anti-static finishes or conductive filaments in seating fabrics. The passive measures include adopting conductive plastics in a steering wheel, seat belt buckle release button, or door opening handle. The effectiveness of these measures was tested in a low humidity environment.

Misfire diagnostics are required to detect missed combustion events which may cause an increase in emissions and a reduction in performance and fuel economy. If the misfire detection system is based on crankshaft speed measurement, driveline torque variations due to rough road can hinder the diagnosis of misfire. A common method of rough road detection uses the ABS (Anti-Lock Braking System) module to process wheel speed sensor data. This leads to multiple integration issues including complexities in interacting with multiple suppliers, inapplicability in certain markets and lower reliability of wheel speed sensors. This paper describes novel rough road detection concepts based on signal processing and statistical analysis without using wheel speed sensors. These include engine crankshaft and Transmission Output Speed (TOS) sensing information. Algorithms that combine adaptive signal processing and specific statistical analysis of this information are presented.

To demonstrate that quantitative design criteria combined with computer analysis methods can facilitate the structural design of an automotive vehicle, two examples of computer aided preliminary design are given. The examples demonstrate analytical techniques applied at two different stages in the design process for a compact size (non-production) automobile. In the first example, analysis is applied to ensure that the front-end structure of the project vehicle is designed to withstand anticipated in-service loads. In the second example, structural dynamic analysis of the total vehicle system is performed to determine vibration response quantities in the passenger compartment. These quantities are compared with whole-body vibration criteria to assess passenger ride quality.

With parts consolidation and increasing systems performance requirements, instrument panel systems have become increasingly complex. For these systems, the use of predictive engineering tools can often reduce development time and cost. This paper outlines the use of such tools to support the design and development of an instrument panel (IP) system. Full-scale test results (NVH, head impact, etc.) of this recently introduced IP system were compared with predicted values. Additionally, results from moldfilling analysis and manufacturing simulation are also provided.

The development of a plasma jet ignition system is described on a 4-cyl, 140 in3 engine. Performance was evaluated on the basis of combustion flame photographs in a single-cylinder engine at 20/1 A/F dynamometer tests on a modified 4-cyl engine, and cold start emissions, fuel economy, and drivability in a vehicle at 19/1 air fuel ratio. In addition to adjustable engine variables such as air-fuel ratio and spark advance, system electrical and mechanical parameters were varied to improve combustion of lean mixtures. As examples, the air-fuel ratio range was 16-22/1, secondary ignition current was varied from 40 to 6000 mA, and plasma jet cavity and electrode geometry were optimized. It is shown that the plasma jet produces on ignition source which penetrates the mixture ahead of the initial flame front and reduces oxides of nitrogen emission, in comparison to a conventional production combustion chamber.

Lear Corporation has developed a new OneStep™ Liftgate trim module. The panel consists of all mechanical components and a trim cover assembled into one module. This structural liftgate uses the trim substrate and a “beam” as the common attachment point for all liftgate hardware. The assembly includes all of the liftgate components mounted to the back of the interior trim panel.

Seat covers made from textiles, leather and vinyl were evaluated for noise absorption. The textiles included woven velours, pile knits and flat wovens. The noise absorption of the covers and the corresponding seat assemblies was tested by the reverberation room method per ASTM C423. The effect of different foams was also tested. For the leather and vinyl covers, the effect of perforation was evaluated. Test results showed distinctive differences between textiles and leather/vinyl with cloth seats having superior noise absorption. Even among the textiles, there are significant differences. Core foam densities affect the characteristics as well. For pile fabrics (woven velours and pile knits), the size of the pile fiber does not affect the acoustic characteristics of the seat. Also, no significant difference was observed between a bonded seat and a conventional (cut and sew) seat.

By design, frontal New Car Assessment Program (NCAP) tests focus on a narrow portion of the spectrum of field crash events. A simple, high level parsing of towaway crashes from NHTSA's National Automotive Sampling System - Crashworthiness Data System (NASS-CDS) files shows that only a small fraction of occupants (but a somewhat larger portion of their harm as measured by ISS) find themselves in crash circumstances remotely similar to NCAP crash conditions. Looking only at seat location, area of damage, direction of force, distribution of damage, and estimated delta-V filters significantly restricts the relevance of NCAP even before critical factors like belt use and vehicle crash partner are considered. Given the limited scope of frontal NCAP it should not be surprising that it has limited usefulness in discriminating among various vehicles' overall performance in the field.

An assessment of automobile painting at General Motor's Lake Orion, Michigan, USA assembly facility from a life cycle perspective was conducted. The Orion Facility produces the new Oldsmobile Aurora and Buick Riviera models. Improvements in on-site pollution prevention, energy conservation and regulatory barriers to technology innovation were identified. The environmental implications of auto body substrate material choice were analyzed. A life cycle inventory framework was developed for paint suppliers and other parts of the auto painting life cycle. An Alternative Regulatory System was proposed for the entire U.S. auto industry that will, if implemented, facilitate the integration of environmental management into core business strategies and planning.

The goal of this study is to assess the total Life Cycle Global Warming Impact of the current HFC-134a (R134a) refrigeration system and compare it with the effect of proposed alternatives, HFC-134a Enhanced, HFC-152 (R152a), R744, R744 Enhanced and R290, based on life cycle analysis (LCA). The enhanced systems include control strategies to elevate the compressor suction pressure as the evaporator load is reduced. The hydrofluorocarbons HFC-134a and HFC-152a are greenhouse gases (GHGs) and are subject to the Kyoto Protocol timetables, which when the treaty takes effect will require participating developed countries to reduce their overall CO2 equivalent emissions of six GHGs by at least 5% by 2012 from 1990 levels.