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An estimate of the rate of attrition of passenger cars, needed to establish the service life expectancy of passenger cars, is of major interest whenever long range production plans are made, marketing strategies are developed, the total needs of vehicles on the roads are estimated, etc. Estimation of vehicle attrition is very complex, however, due to the lack of accurate data and the interaction of the parameters affecting attrition. In 1980 and 1985, similar studies of attrition [1,2] utilized vehicle registration data available as of July, 1979 and as of July, 1984. The object of this paper is to update the results of these papers, using the 1991 July registration data, available in May 1992. Within the scope of this paper the attrition rates of various passenger cars are compared and the effect of geographical location on the attrition rates and the change in attrition rates during the past twenty years are discussed.

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.

This paper contains a technical description of the Ford Motor Co.'s ACT system which has been designed to meet transportation needs in a wide variety of urban applications. The discussion covers the systems design features and operation of the driverless rubber-tired vehicles, the guideway, and the system's ability to meet expanding needs by a modular approach to the command and control design. Descriptions of Ford's new Cherry Hill Test Track and the first installations at the Fairlane Town Center in Dearborn, Mich., and the Bradley International Airport, Hartford, Conn., are also presented.

Powertrain mounts are one of the important design characteristics of a vehicle. Powertrain is mostly mounted to the front subframe and once installed in a vehicle, powertrain mounting has an important role in determining the vehicle vibration characteristics. A good mounting system isolates engine input vibration from the vehicle body and minimizes the effect of road inputs to the customer. This paper discusses results of several dynamic models as they relate to noise, vibration and harshness (NVH) and compares the accuracy of these models. Various powertrain models are studied and their accuracy in comparison with full a vehicle model is discussed.

This paper outlines an approach to highway transportation research which considers the interrelationship of the major subsystems. It describes the framework, the variables, surveillance techniques, and new vehicle instrumentation. A model is described which serves as the basis for field testing and subsequent mathematical analyses. Surveillance systems including instrumented vehicles, ground, aerial, and space platforms are required as components of a real-time system. A research project, designed to evaluate driver stress, is discussed and sample computer data are shown.

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.

The design requirements for the frame as a load carrying member are discussed in relationship to a highway truck and its basic vehicle package. The theoretical and experimental procedures are given in detail to demonstrate the techniques for frame design. The features of a method to laboratory test a frame with correlation to service miles is discussed.

The object of this paper is to develop a random vibration laboratory test specification for automotive subsystems using the Power Spectral Density (PSD) method. This development is based on the 150k mile field data collected from vehicle proving grounds. The simulated vibration bench test will be used to simulate the energy of the 150k mile field data. The developed specification will include 3 axis random vibration profiles of appropriate duration. The Power Spectral Density method converts the time-domain field data into the frequency-domain data. The Enveloped Energy method groups the similar road PSD profiles to produce a generic PSD profile. The Inverse Law allocates an adjusted duration to the desired PSD energy level. The Road Test Specification provides the duration time for the developed bench test. The n-Soft tool [1] is utilized for data reduction analysis. The Bench Test Specification of the Fuel subsystem is a pilot for this development.

THE study of engine life, carried out by investigating engine wear in typical service, and by then striving to find the most effective ways of controlling it, forms the basis of this paper on contaminants in lubricants. The investigation involved a study of engine wear in 20,000 miles of operation typical of the average driver. The average driver was selected by using test cars from an employee transportation car pool. At the conclusion of the tests it was found that the use of the full-flow oil filter proved to be the best method for restricting engine wear caused by contaminants that get inside the engine. It was also shown that after successfully eliminating large, solid particles, further restriction of engine wear would depend upon the ability of the oil to lubricate, and upon the engine design to provide the oil supply in a manner suitable for lubrication of each part of the engine.

This paper describes experimental methods for simulating and analyzing road noise using an artificial road surface mounted to a chassis dynamometer. The nature of the relationship of road noise to road surface is discussed, including the nature of sound produced by the artificial surface mounted to the dynamometer. A method is described for converting the harmonics usually produced in a chassis rolls test into a continuous spectrum. This method also smoothes statistical fluctuations which arise due to the short length of road simulated. Dynamometer techniques are shown to be particularly effective in separating sound contributions from the front and rear suspension, and in separating contributions due to road surface and the tire tread.

The safety and comfort aspects of passenger cars are significant sales argument and have become a topic of rising importance during the development process of a new car. The objective of this study is to compare the performance of several current model vehicles, highlight the drawbacks of current defrosting/demisting systems and point the way to improved passive mechanisms. The investigation is experimental. The experiments are carried out using full-scale current vehicle models. The results show that the current designs of the defroster nozzle give maximum airflow rates in the vicinity of the lower part of the windshield, which decrease gradually towards the upper parts of the windshield. This hinders and limits the vision of the driver, particularly at the top of the windshield, which can be uncomfortable and indeed dangerous.

Vehicle operation noise, even in the quietest cars, produces high sound pressure levels (SPL) at very low frequencies. This noise masks desired signals in and above this frequency range. A blind subjective test, using ten listeners, was undertaken to determine a frequency response equalization curve that would compensate for this noise under specific but realistic conditions. Starting with a 4 dB full-band level increase, an average of 40 listener responses showed a gentle rise in bass reaching an additional 4 dB at 50 Hz.

The increasing competitiveness in the automobile market has resulted in the incorporation by the manufacturers of certain features in newer cars that are deemed highly desirable by the customer. Among such features that require improvement is the thermal comfort of passengers' within the cabin. Thermal comfort is in increasing demand from motorists bound to cover more mileage driving cars than ever before. As a result, car makers are striving for improved climate conditions inside the car to meet passenger demand for more comfortable trips. The need to improve the climatic comfort within the vehicle is critical not only to passengers' comfort but also to their safety. However, to make progress in this area, a good understanding of the airflow behaviour within the vehicle interior is required. This paper, reports on a novel idea of control the air movement within the cabin by forcibly removing the air from strategically positioned vents.

Downhill tests are widely used as a method of evaluation, development and validation of braking efficiency, friction pair durability, braking balance, as well as fade characteristics and recovery of friction material properties. This test procedure is used for both: passenger vehicles and light & heavy commercial vehicles. The energy levels in the brake system are higher on commercial vehicles and the thermal characteristics much more critical. Added to the fact that such tests are conducted on public highways, it has an intrinsic security risk for both the vehicle tested and all others around. Until a few years ago, it was still feasible to conduct tests downhill on different routes keeping a high security level. Given an increasing traffic on highways, where the test is currently carried out, a need to create a similar downhill procedure (called Guaporé Mountain Test) within a Proving Ground under controlled conditions has been noticed.

This paper proposes to utilize the Automobiles Entertainment Audio and Cellular Phone Systems as an information terminal to access the Information Super Highway better known as the WorldWide Web. As society moves to an ever increasing information based technology, there will be an ever expanding need to provide new ways and means of allowing access to the data on the WorldWide Web and Internet from many various locations and at a variety of different times. The authors recognize that rather large amounts of data and research have conducted and presented relative to obtaining information from and across the WorldWide Web. Additionally much work has been expended in the development of enhanced Driver Information Systems within the Automotive Industry.

TWENTY-FIVE-YEAR statistics, detailed in this paper, show declining accident and fatality rates despite radical increase in vehicle registrations and annual vehicle miles. The author shows how the passenger-car industry has built safety into vehicles to the point where-as an example-only 14% of accidents on the Pennsylvania Turnpike over its 13-year history were attributed to vehicle failures. Paralleling these efforts and the increasing emphasis on safer highways, better traffic management and driver education, are extensive studies aimed at bypassing the human factor and increasing human safety in automotive vehicles. Among those described here are crash investigations, laboratory tests of safety devices, and establishment through various other means of design criteria for human impact tolerance.

The evaluation of the performance benefits of solar load reducing glazings using production vehicles is key to the establishment of the product cost/benefit ratio. Climatic windtunnels normally used to evaluate heat gain and vehicle cooldown can not provide true solar simulation. Comparative testing using a test car and a control vehicle must therefore be conducted outside in uncontrollable ambient conditions. The subject paper deals with the development of a testing methodology capable of quantifying thermal performance differences, as low as 5%, resulting from component differences, including glazings. The procedure described includes the use of B & K Thermal Comfort Meters to standardize the refrigeration system performance and to evaluate the rate of vehicle interior cooldown. Data taken during summer test programs in the Southwest for evaluation of heat absorbing glazings will be reviewed.

Ford’s use of digital mockups in vehicle design has improved the package and fit of components and systems within the vehicle. However, to fully meet and exceed the consumer’s expectations of a vehicle it is crucial to make subjective evaluations of a vehicle’s comfort, convenience, visibility, and accessibility early in the design process. Efficient and nimble design requires an understanding of the subjective qualities of the vehicle before any physical prototypes exist. The Digital Occupant personally immerses an individual (e.g. member of the design team, market researcher or consumer) within the digital mockup earlier to facilitate these subjective evaluations. This paper describes the technologies and emerging methodologies integrated to produce the Digital Occupant. This personally immersive simulation includes a full body real-time dynamic digital representation of the individual being immersed.

The approximate population of passenger cars in service and the rate of attrition of that population must be known when long range production plans are made, marketing strategies are developed, the total fuel need of the vehicles on U.S. roads is estimated, etc. Estimation of population is complex due to the lack of accurate data and the interactions between the parameters affecting attrition. Various methods are available to estimate the present and future population levels of passenger cars in service. Within the scope of this paper the projected populations of various passenger cars are compared and various attrition projection methods are discussed.

Since the door glass windows are used regularly, they have a great influence on the vehicle owner's perception of vehicle quality. Today's customers demand that moveable door window glass operates smoothly. Experimental methods have been developed to evaluate window glass smoothness and positional stability. This paper presents experimental results that quantify the chattering and positional stability of the window glass. For window glass smooth operation and tracking, the measurements were taken on glass chatter, glass velocity, motor current, motor voltage, and glass stall force. The change in glass position was measured on the vehicle during several stages of four poster durability testing to evaluate window glass positional stability during road induced vibrations. Using these experimental methods, the designers should be able to evaluate several window glass functional requirements and achieve cost/time savings.