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Technical Paper

Electrically Propelled Vehicles at BMW - Experience to Date and Development Trends

1991-02-01
910245
Back in the first two decades of automobile development, electric propulsion was a serious competitor for the internal combustion engine. Electrically-propelled vehicles, however, soon proved unable to satisfy users' increasing performance demands in terms of range, acceleration, top speed and hill-climbing, together with such factors as operating life, initial purchase price, running costs and reliability. Engineers investigating electric propulsion today face precisely the same unwelcome legacy as their predecessors, despite many and varied attempts in the meantime to improve the components of the electric vehicle's drive system (energy storage device, motors, controller). Progress in battery development, particularly in the case of the NaS system, has nevertheless enabled us at least partly to overcome the previous problems associated with electric drive systems, though it cannot be claimed that all obstacles to its commercial application have been eliminated as yet.
Technical Paper

Natural Gas Hybrid Electric Bus

1991-02-01
910248
The design and predicted performance of a hybrid electric powered transit bus is described. The bus is a 7.6 meter (25 ft), 24 passenger vehicle that incorporates a low floor design and rear door accessible to handicap passengers. The low floor and rear door are made possible by the use of individual high power density permanent magnet motors driving the rear wheels. The hybrid electric drive system consists of a compressed natural gas fueled internal combustion engine that drives a generator which in conjunction with storage batteries supply power to the two traction motors.
Technical Paper

An Examination of the Maneuverability of an All Wheel Steer Vehicle at Low Speed

1991-02-01
910241
With the goal of improving the driver's steering performance, the four(all) wheel steering(4WS) system was designed, and theoretical and experimental analysis of the 4WS system was investigated. In the 4WS system the low speed maneuverability is better due to a smaller turning radius. In reality, however, the opposite steering of the rear wheels could be counter-productive for certain maneuvers as shown in the Fig.1. In this paper, this counter-productivity is called the parking problem. The objective of this study is to prevent the parking problem and to maintain the maneuverability of the 4WS vehicle. To accomplish this goal, a new concept of the 4WS system for the low speed range has been introduced.
Technical Paper

Electric Vehicle Development in Fiat

1991-02-01
910244
Within the strategical scope of energy conservation and improvement of human quality of life FIAT is since long time performing activities aimed at the technologies for electrically propelled vehicles for diversified applications. The electricity as energy vector allows an application flexibility to different types of vehicles, full electrics hybrid and multimode vehicles which have been developed at prototypes level or small scale production. The tactical process which has been followed is based on the three phases of: technology research and development demonstration programs and field trials production. The experience achieved within several extensively tested prototypes and pilot service allowed to put in small series production light and medium delivery vans as well as minibuses, which are now in service in Rome and other italian cities.
Technical Paper

Performance Testing of the Vehma G Van Electric Vehicle

1991-02-01
910242
This paper presents the results of performance characterization testing of two prototype Vehma G Van electric vehicles (EVs). Testing was performed at the Electrotek Electric Vehicle Test Facility (EVTF) as part of the Electric Power Research Institute (EPRI)/Electrotek EV Program. The G Van is a GMC full-sized van converted to electric propulsion by Vehma International of Toronto, Ontario. One of the vans tested at the EVTF was a five-passenger model, the other was a two-seat cargo van. These vehicles utilize tubular-plate lead-acid batteries and dc powertrain system components produced by Chloride EV Systems of Redditch, England. Performance testing was conducted according to the EPRI/Electrotek EV Test Plan and included measurement of driving range at 56 km/h, on the SAE J227a C cycle, and on the Electrotek-defined Urban route. Vehicle top speed, maximum acceleration, dc and ac energy consumption, hill climbing, and braking capabilities also were measured.
Technical Paper

Effect of Lateral Tire Flexibility on the Steering System Dynamic Behavior

1991-02-01
910239
The purpose of this paper is to investigate the influence of tire lateral flexibility on the steering system dynamic behavior. Individually, the steering models and the lateral flexible models have been investigated for a long time. However, the combination of both hasn't yet drawn much attention. The inclusion of the lateral (rigid) tire model has shown to be of great importance. This study attempts to scrutinize the influence of a more practical tire model on the steering dynamic performance. Included in the study, Transient response as well as frequency response are illustrated by tables and figures.
Technical Paper

The Importance of Tire Lag on Simulated Transient Vehicle Response

1991-02-01
910235
This paper discusses the importance of having an adequate model for the dynamic response characteristics of tire lateral force to steering inputs. Computer simulation and comparison with experimental results are used to show the importance of including appropriate tire dynamics in simulation tire models to produce accurate predictions of vehicle dynamics. Improvements made to the tire dynamics model of an existing vehicle stability and control simulation, the Vehicle Dynamics Analysis, Non-Linear (VDANL) simulation, are presented. Specifically, the improvements include changing the simulation's tire dynamics from first-order system tire side force lag dynamics to second-order system tire slip angle dynamics. A second-order system representation is necessary to model underdamped characteristics of tires at high speeds. Lagging slip angle (an input to the tire model) causes all slip angle dependent tire force and moment outputs to be lagged.
Technical Paper

An Experimental Investigation of Passenger Car Tire Properties at High Slip and Camber Angles

1991-02-01
910233
A newly designed and built Mobile Tire Testing Machine (MTTM) is described that has features for large and continuously variable camber and steering angles with minimum tire scrub. This equipment was used to examine tire properties for six passenger car tires. Of special interest were the tire characteristics at combinations of high slip and camber angle. It was found that camber stiffness decreases with increasing slip angle when the slip and camber angles are both positive, and at limit conditions in slip angle, cambering a tire has little effect on the lateral side force produced. When the slip angle is negative, and the camber angle is positive, preliminary data shows that a greater lateral force is produced when compared to operating at limit conditions in slip angle alone.
Technical Paper

Zinc-Air Powered Electric Vehicle Systems Integration Issues

1991-02-01
910249
Dreisbach ElectroMotive, Inc. (DEMI) is developing and testing a maintenance-free wall-plug rechargeable Zinc-Air Battery to power Electric Vehicles. This new battery technology offers over 200 mile vehicle range capability from very low cost, commonly available raw materials. This paper will focus on the preliminary systems integration needed by an electric Vehicle to operate these air breathing batteries in various common environments. Air cooling and reaction air requirements will be covered as well as the actual systems used to implement these requirements in a Chrysler minivan* which is sponsored by Southern California Edison (SCE). In addition, the projected system implementations of Zinc-Air batteries in automobiles and multi-use vans will be presented.
Technical Paper

Climate Control for Electric Vehicles

1991-02-01
910250
The vast majority of cars and small trucks are sold with factory installed air conditioning (approximately 80% in 1989). For electric vehicles to succeed in the marketplace, air conditioning will need to be offered as optional equipment, along with adequate heating and defrosting systems. While providing the level of cooling performance expected by vehicle operators, it is important that the power consumption of the air conditioning systems used in electric vehicles be minimized, to minimize penalties to vehicle range and performance. This paper summarizes the design and performance of several air conditioning systems that have been developed for electric vans over the past two years, including systems based largely on standard automobile air conditioning components and more advanced systems using high performance heat transfer components and a variable speed refrigerant compressor.
Technical Paper

A High Torque, High Efficiency CVT for Electric Vehicles

1991-02-01
910251
Epilogics, a young engineering firm in Los Gatos, CA, has developed the first fully geared, high torque, high efficiency, infinitely variable transmission suitable for automotive applications. The IVT has particular significance to electric vehicles because it can provide a highly efficient, yet exceptionally controllable means to regenerate power throughout the normal braking cycle (allowing regeneration even at near-zero vehicle speeds). Under normal operating conditions, the efficiency of the Epilogics transmission exceeds 90% as derived mathematically and corroborated experimentally. The device does not rely on traction to transmit torque and can therefore match the torque capacity of any typical gear drive. The size, weight, and cost of the device closely approximates that of a four-speed transmission suitable for the application.
Technical Paper

The Modelling and Calculation of a Turbulent Premixed Flame Propagation in a Closed Vessel: Comparisons of Three Models With Experiments

1991-02-01
910265
The modelling of a turbulent premixed flame propagating in a constant volume vessel has been studied and compared with experiments. Three models including step by step the turbulent mixing, the flamelets propagation for wrinkled flames, and the flamelets stretching, interactions and thickening when the chemistry is not very fast, have been tested. The experiment considered here allows the knowledge of the turbulent kinetic energy and the turbulence scale at the time of the spark, and avoid any problem of spark fluctuations and residual gases, but displays again “cyclic variations” and the comparison concerns ensemble averages. The results of comparisons is that the agreement concerning the flame brush propagation is improved from the simplest to the largest model, when considering a domain in which in which varies from 2. to .75 and from 2. to 0.4 .
Technical Paper

Estimation Method of Tire Treadwear on a Vehicle

1991-02-01
910168
Tire treadwear is a very complicated phenomenon that is influenced by various factors. Any quantitative treadwear estimating method applicable to tires on a vehicle has not yet been established. In this study the effects of acting force to the tire and tire attitude (dynamic wheel alignment) upon treadwear were made clear experimentally by taking notice of the fact that they are only the factors directly influencing tire treadwear provided that a tire and a road surface are determined. Furthermore, on the assumption that treadwear will increase linearly, an examination was made to find a method of estimating treadwear of tires on any vehicle in any running condition by using above-mentioned effects for the values of tire-acting force and dynamic wheel alignment calculated from the vehicle particular and running condition.
Technical Paper

Reinforcing Materials for More Fuel Efficient Tires

1991-02-01
910169
Both the current legislative trend proposing to mandate more fuel efficient automobiles and responsible corporate environmentalism require suppliers to develop materials that will enable both vehicle and component manufacturers to engineer lighter and/or more fuel efficient systems for all vehicles. One such system is the tire, where the reinforcing materials for the elastomer can have a significant effect on tire weight and rolling resistance. This paper reviews some of the materials now available for reinforcing tires and what impact these may have on the ability to design tires with potential to improve fuel efficiency. In particular, it discusses aramid yarns and nylon monofilaments for tire reinforcement and their effect on tire weight and rolling resistance. Additionally, the use of short fiber aramids for blending with elastomers to directly modify bulk physical properties and increase design freedom while maintaining critical properties is covered.
Technical Paper

Emergency Braking Test of the Ice and Snow Tires on Iced Drum Tester

1991-02-01
910167
This paper describes a test method that evaluates the emergency braking capability of a tire on ice using an ice-covered drum tester. The value of the braking force is affected by the amount of crushed ice stuck to the tire. With a low rotation speed for the tire, this effect can be reduced. Utilizing this technique, braking force - velocity characteristics on ice at various temperature are obtained.
Technical Paper

Fuel Injectors in Diesels With Large Needle-Barrel Clearance

1991-02-01
910183
An attempt to operate a diesel engine using the so-called hydraulic fuel injector with large clearance between the needle and its barrel was carried out experimentally. In this type of injectors, the spring force was substituted by a pressurized hydraulic oil to control the needle motion. Various factors affecting the injection system, for both hydraulically and spring loaded injectors, were also theoretically simulated and tested. The present study confirmed. according to both the experimental and theoretical results, that the use of hydraulic closer of needles is a promising technique to overcome the problem of diesel engine operation with large needle clearance (7 times the standard). To maintain the best specific fuel consumption by the engine, the injection timing has to be readjusted in accordance with the increase in the needle clearance.
Technical Paper

Environmental Monitoring Technologies

1991-02-01
910190
Six defense-related technologies that appear to have application to environmental monitoring are reviewed. Thermal imaging of the sort used in heat seeking missiles provides a means of rapidly surveying an area for possible presence of pollutants. A compact wedge filter spectrometer can be used to remotely determine the spatial distribution of classes of pollutants, while a Fourier transform infrared (FTIR) spectrometer has been shown to identify specific pollutants at distances of seven kilometers. A remote active spectrometer using tunable carbon dioxide (CO2) lasers has been shown to give accurate results at 3.5 kilometers; this capability can be extended to the near IR region by using upconversion lasers. A fiber optic evanescent wave liquid level sensor is described that may find application as a leak detector for underground storage tanks.
Technical Paper

New Approaches to Electronic Throttle Control

1991-02-01
910085
An electronic control of throttle angle is required for safety systems like traction control (ASR) and for advanced engine management systems with regard to further improvements of driving comfort and fuel economy. For applications, in which only ASR is required, two versions of a new traction control actuator (TCA) have been developed. Their function is based on controlling the effective length of the bowden cable between the accelerator pedal and the throttle. Besides retaining the mechanical linkage to the throttle, the concept has no need for a pedal position sensor, which is necessary for a drive-by-wire system. Design and performance of both actuators are described and their individual advantages are compared. Moreover, the communication of the system with ASR and its behaviour with regard to vehicle dynamics are illustrated.
Technical Paper

Controller for Experimental Vehicle Using Multi-Processor System

1991-02-01
910086
Recently, active control technology of vehicles has extensively been developed. An experimental vehicle with independent hydro-pneumatic suspensions was constructed in our laboratory for the improvements in vehicle dynamics and ride-comfort. The vehicle includes a controller, mainly consisting of a multi-processor system with 5 CPUs. By combining this new system with a common bus, all CPUs can immediately access peripherals impartially without particular software. The CPUs can also acquire the data of sensors from the memory in the A/D module at any time without special software. The CPUs are shared to synthetically control the attitude and vibration of each vehicle wheel. Therefore, high capacity is exhibited by a simple system at low cost. The performance of the controller was examined by actual running tests using the experimental vehicle, confirming the improvements in vehicle dynamics and ride-comfort, such as reduction in roll angle and vibration.
Technical Paper

The Driving Simulator with Large Amplitude Motion System

1991-02-01
910113
An Advanced driving simulator has been developed at Mazda Yokohama Research Center. The primary use of this simulator is to research future driver-vehicle systems. In an emergency situation, a driver must respond rapidly to perceived motion and visual stimulus to avoid an accident. In such cases, because the time delay associated with the perception of motion cues is shorter than visual and auditory cues, the driver will strongly rely upon perceived motion to control the vehicle. Hence, a driving simulator to be used in the research of driver-vehicle interactions in emergency driving must include a high performance motion system capable of large amplitude lateral motion. The Mazda simulator produces motion cues in four degrees of freedom, provides visual and auditory cues, and generates control feel on the steering wheel. This paper describes the merit of the large amplitude motion system and the features of this newly developed driving simulator.
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