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The Mobile Tire Traction Dynamometer measures the braking and cornering traction of passenger car tires on outdoor pavements at highway speeds. Its hydrostatic wheel speed control system, wheel loading and positioning system, pavement wetting system, transducers and instrumentation are described in detail. The data processing methods for its several test modes are explained. Results of experiments (1) to determine the effect of the rate of change of slip on the peak braking coefficient, (2) to identify filters suitable for peak braking coefficient measurement, (3) to determine the effect of the rate of change of slip angle on the lateral force coefficient, and (4) to explore various pavement friction testing methods are included as examples of the use of this testing device.

New Federal safety legislation requires school bus body manufacturers to increase the strength of all joints between sheet steel body panels and between panels and support beams. This paper describes two new epoxy structural adhesives, and a new assembly process called “rivet bonding”, which is now used for about 98% of all school buses produced for sale in the U.S. Advantages include noise reduction plus substantial savings in labor and other costs when compared to the riveting or other mechanical fastening methods which would be required to provide equivalent joint strengths.

EEC Braking Directives mandate several system functions that require special equipment, in order to gain Type Approval. Industry, generally, exerts pressure to ensure that legislation is not design restrictive and, since the major manufacturers of air brake equipment are based in Britain and Germany, where the brake systems prior to 1971 were quite different, there are some interesting contrasts in the valves and system principles employed to meet the same requirements. Interpretation of the Directives and establishment of uniform test methods have given rise to several problems and this continues to be a field in which much work is required. Consequently, a period of stability is sought before further changes are introduced.

The rationale for the increasing use of automotive adhesives is discussed as are the basic principles of adhesive and process selection. The paper concludes with a brief summary of why adhesives are used in thirteen different automotive applications.

Exhaust gas recirculation is an effective means to reduce NOx-emissions of Diesel engines. Unfortunately too high EGR rates increase the emissions of hydrocarbons, carbon monoxide and soot. So EGR has to be controlled precisely. The paper describes an EGR-system for Diesel engines which senses the air-flow and the fuel-flow of the engine and limits the EGR-rate so, that the air-fuel-ratio is lean enough for a clean combustion. Furthermore the paper shows the emission results which have been obtained with the described EGR-system on different Diesel passenger cars.

The potential and current distribution over the grid of a lead-acid battery can be calculated by applying Kirchoff's Law to a three-dimensional resistance network analog. Such a model was used to simulate the highrate discharge of a typical grid having a conventional, uniform pattern of grid members. The potential and current density were found to vary widely over the grid surface. Modifications to the design of the grid make the potential and current density distribution more uniform, which would lead to more efficient utilization of the battery active materials, and an improved battery performance.

The interdependence between gross vehicle weight, curb weight, payload and drive weight is established in general for electric vehicles. Based upon the FAKRA Driving cycle, the range is expressed as a function of gross vehicle weight for electric vehicles equipped with different types of storage devices. The cost for operating these vehicles is calculated and compared.

Tests of seventeen electric vehicles were analyzed to estimate tire friction, aerodynamic drag-area product, and average motor-driveline efficiency. The tests included coastdown runs, range over the SAE J227a driving schedules (B, C, and constant speed), and constant-current battery discharges. Analysis indicates that winds during coastdown tests resulted in average standard deviations of seven percent for tire friction, and fifteen percent for drag-area product. Motor-driveline efficiency estimates ranged from 40 percent to 93 percent (fifteen vehicles, J227a/B schedule), and from 61 percent to 93 percent (eleven vehicles, J227a/C schedule).

To find the minimum range, speed, and capacity required to meet most needs of urban drivers, origin-destination surveys from Los Angeles and Washington were processed to determine driving patterns for a typical day. The survey data indicates that ranges sufficient for 95% of driving days would be 75 km for secondary drivers, 150 km for only drivers, and 225 km for primary drivers at urban households. Similarly, speed adequate for freeway use is required to satisfy driver needs on 95% of driving days, with seating for at least two and generally three passengers in addition to the driver.

The advanced hybrid electric-powered vehicle features a regenerative power system that uses a flywheel that supplements lead-acid battery power during peak power demands for current leveling, and that converts vehicle kinetic energy to retrievable flywheel energy by means of regenerative braking. The process of energy storage and conversion to propulsion power is accomplished by a unique arrangement of the flywheel, generator, motor, and final power drive shaft connected by a differential planetary gear set.

A digital computer program has been developed that simulates dc and ac electric vehicle operation. Included in the program are battery, controller and motor models which are designed to be easily modified as new drive systems are developed. The simulation technique used accurately models the time response of the vehicle and has proven useful in the design and stability analysis of vehicle control systems.

A method for modeling electric vehicles has been developed and applied in the prediction of electric vehicle performance and range over variable driving cycles. This model is also applicable for studies of the size, power rating, and costs of electrical drivetrain components. The details of the battery and motor simulation used in the model are described. The battery simulation characteristics are compared with the results of life-cycle tests performed on lead-acid batteries. A method for sizing and rating a battery for electric vehicle applications is suggested.

A new type of pressure sensor has been introduced into the 1978 production automobile. This design, consisting of a unique capacitive approach, requires the use of only one moving part to produce a voltage output which is proportional to the input pressure signal. The simple construction combined with field and bench performance tests has demonstrated a sensor which possesses high durability and repeatability at a modest product cost.

The crankshaft position sensor (CPS) is a variable reluctance magnetic sensor which accurately senses the position of four teeth equally spaced 90° apart on a toothed ring attached to the crankshaft. The electronic engine control (EEC) calculates RPM using two adjacent pulses, and with other processed information, calculates spark advance. Actual spark initiation again uses the CPS as a reference position. The properties and environment of the sensor which determine accuracy, noise, and other characteristics important in its interface with the system is discussed.

An experimental sensor has been developed to indicate the air-fuel ratio of an engine operating on lean mixtures. Stabilized zirconia doped with iron was used as the sensor electrolyte. These sensors are internally temperature compensated, eliminating the need for additional temperature sensing or electronics. Sensor output is responsive to exhaust oxygen content, but is independent of exhaust temperatures above 450°C at 18:1. Addition of iron increased uniformity of output among sensors.

WITH THE DEVELOPMENT of the Ford Electronic Engine Control System to meet increasing emission and fuel economy requirements, the need arose to accurately assess engine coolant and inlet air temperatures in order to properly control exhaust gas recirculation flow and spark timing. This paper will discuss the design of the temperature sensors developed for that purpose. The sensors meet the functional requirements of the control system and are durable and reliable. The basic design is also readily adaptable to many other temperature sensing applications.

This paper describes the application of automotive sensors to electronic control of the internal-combustion engine, with emphasis on sensor-signal characteristics and utilization. Manifold absolute pressure, crankshaft position, throttle position, temperature, and exhaust-gas recirculation are among the parameters monitored to electronically regulate engine inputs. Also presented are a number of control concepts realized with these sensors.

The use of microprocessors in automotive electronics systems such as Electronic Fuel Injection (EFI) and Electronic Fuel Management (EFM) has created a need for a variety of precision position-sensors capable of reliable performance in underhood environments. This paper describes the basics of precision potentiometers and switches which have been adapted for these and other specialized engine applications. A brief description introduces the precision potentiometer as a position-sensor, and details the differences among the more common types of potentiometers. The fundamental low cost position-sensor concept is elaborated upon with a discussion of some of the special materials and techniques used to develop units for automotive applications. Among the special problems discussed are requirements of long life at high temperature, high vibration environment, and stringent performance accuracy.

The Wiegand Effect is a new magnetic phenomenon occurring in a specially work-hardened small diameter ferro-magnetic wire. When subjected to an appropriate magnetic field, a sudden, very rapid flux change occurs. A substantial voltage pulse may be induced in a sensing coil wound around the Wiegand wire, or in its proximity. No electrical input is required, and with the appropriate excitation the pulse is essentially independent of the rate of flux change of the externally applied field. The characteristics of the Wiegand Effect are of interest in a number of automotive applications.

The paper presents an overview of developments on the principal sensors applicable to automotive engine control through brief descriptions of the more important sensor concepts for the various parameters, and an indication of sensor status. The parameters covered are manifold absolute pressure (MAP), manifold vacuum (MV), ambient absolute pressure (AAP), crankshaft position (speed), mass air flow, fuel flow, coolant temperature, air temperature, oxygen partial pressure, and throttle position. Special sections are included covering sensor developments overseas, and describing noteworthy efforts of the SAE and the International Standards Organization (ISO) with respect to engine sensor standards.