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Technical Paper

Electric Hybrid Drive Systems for Passenger Cars and Taxis

1991-02-01
910247
Various hybrid drive configurations are described and their advantages and disadvantages for application in passenger cars are discussed; specifically, these are the series hybrid, the parallel hybrid, hybrid drives with added torque and speed, single and two-shaft hybrids. The Volkswagen and AUDI group has developed different vehicles with hybrid drive for various applications. These vehicles are described and test results are presented on their energy consumption, emissions and driving performance. In conclusion, some considerations are pursued concerning their chances on the market in different scenarios.
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

Track and Dynamometer Testing of the Eaton DSEP Minivan and Comparisons with Other Electric Minivans

1991-02-01
910243
Track and dynamometer testing of the Eaton Dual Shaft Electric Propulsion (DSEP) minivan has been performed by the Idaho National Engineering Laboratory (INEL). The dynamometer testing included constant speed tests up to 88 km/h and driving cycle tests on the SAE J227a C and D cycles and the Federal Urban Driving Schedule (FUDS) as well as maximum effort acceleration tests. The dynamometer data were analyzed to determine the energy consumption (Wh/km) of the DSEP vehicle for the various driving modes and to project the range of the vehicle if the NiF170 nickel-iron battery had been at its rated capacity. Ranges of 90-125 miles at constant speeds and about 70 miles on the driving cycles were projected. Comparisons were made of the performance of the DSEP vehicle and the ETX-II and the TEVan minivans, which have been developed on other DOE and EPRI programs using lead-acid, nickel-iron, nickel-cadmium, and sodium-sulfur batteries.
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

The Use of Intake and Exhaust Measurements with Computer Simulations to Investigate the Evolution of the Internal Flow Field in a Ported Engine

1991-02-01
910262
Recent measurements by of gas intake flows and exhaust pressure in a motored, ported, single-cylinder engine with strong swirl and roll have been used as boundary conditions to a three-dimensional, transient computer simulation of the flow within the cylinder. For each condition, the calculation is continued over several engine cycles until the periodic solution is obtained. The computed TDC tangential velocity and turbulence intensity are then compared with measured ones. A technique is described to evaluate scavenging efficiency, the fraction of charge that remains in the cylinder over later cycles and the degree of mixedness of fresh and residual charge. For this motored ported engine, it is found that the scavenging efficiency is very low (19.4% at 1200 RPM) and the inflow from the exhaust ports is very significant. For practical ported engines with combustion, the scavenging efficiency is much higher but the inflows from exhaust ports are still expected to be significant.
Technical Paper

Study of Swirl Effects on Spray Formations in D.I. Engines by 3D Numerical Calculations

1991-02-01
910264
Spray formations of three injection directions against swirl have been investigated by means of 3D numerical calculation, in-cylinder measurement, and engine performances tests. A direct injection type engine which has a single hole nozzle and a spark plug, has been operated, and three injection directions; a forward (same) direction, a reverse one, and a right-angled (central) one against a swirl direction, have been selected. Three types of intake port, futhermore, have been selected owing to create three types of in-cylinder flow, low swirl, middle swirl, and high swirl. Spray formations in 3D cylinder flow have been investigated by using a ‘KIVA’ code. Initial conditions of in-cylinder flow are based on data which have been measured in three dimensional by a LDV system under a motoring operation. Analysis results of spray formations by numerical calculations can explain well data of engine performance tests qualitatively, and some interesting results have been obtained.
Technical Paper

Numerical Simulation of Swirling Port-Valve-Cylinder Flow in Diesel Engines

1991-02-01
910263
A CAD/CAE procedure has been used for the analysis of the flow in an intake port-valve-cylinder assembly of a DI Diesel engine. The flow was simulated for both, steady state conditions and transient motored situation during intake and compression strokes. The characteristics of the helical port are analyzed, for the steady state case, in terms flow rate, generation of angular momentum flux and induced in-cylinder flow motion. The results of the simulation were correlated with experimental results, consisting of oil film visualizations on valve and intake port surfaces, and of local velocity measurements in the cylinder. The transient flow simulation shows the different characteristics of the flow motion in cylinder and piston bowl during intake and compression strokes. It was observed that the swirl generating capacity of the valve is different between the valve opening and closing phases.
Technical Paper

SI Engine Controls and Mean Value Engine Modelling

1991-02-01
910258
Many existing classical electronic control systems (speed-throttle, speed-density, MAF (mass air flow)) are based on quasistatic engine models and static measured engine maps. They are thus time consuming to adapt to new engine types, are sensitive to dynamic sensor errors and in general have undesirable dynamic characteristics. One of the main reasons for the characteristics of these strategies has been the lack of a precise, systems oriented, equation based, dynamic engine model. Recently a compact dynamic mean value engine model (MVEM) has been presented by the authors which displays good global accuracy. A mean value model is one which predicts the mean value of the gross internal and external engine variables. This paper shows how the engine model can be applied to the systematic design and analysis of classical electronic engine control systems. One of the main aims of the paper is to eliminate the use of cut and try methods in designing dynamic engine controls.
Technical Paper

Stratification of Swirl Intensity in the Axial Direction for Control of Turbulence Generation During the Compression Stroke

1991-02-01
910261
Control of turbulence during the compression stroke is suggested by both theoretical calculations and experimental results obtained with an LDV measurement in a motored engine. The authors have found experimentally that when an axial distribution of swirl intensity exists, a large-scale annular vortex is formed inside the cylinder during the compression stroke and this vortex generates and transports turbulence energy. A numerical calculation is adopted to elucidate this phenomenon. Then, an axial stratification of swirl intensity is found to generate a large-scale annular vortex during the compression stroke by an interaction between the piston motion and the axial pressure gradient. The initial swirl profile is parametrically varied to assess its effect on the turbulence parameters. Among calculated results, turbulence energy is enhanced strongest when the swirl intensity is highest at the piston top surface and lowest at the bottom surface of the cylinder head.
Technical Paper

An Adaptive Engine Control Algorithm for Acceleration Response

1991-02-01
910256
Chassis back and forth oscillation caused by sudden engine torque increase tends to occur, according to the characteristic of vehicle dynamics. This oscillation is called an acceleration surge and gives a vehicle driver a feeling of discomfort. This paper provides two control methods which can change the characteristic of vehicle acceleration response in order to suppress acceleration surge and to macth with driver's preference. The first control method is an acceleration servo method which is composed of control reference model and ignition timing control. The second control method is a variable response characteristic control algorithm. We treat the controlled object as the second order model with time delay, and assign the characteristic roots of transfer function in order to obtain the desired response.
Technical Paper

Control System for a Low Emissions Natural Gas Engine for Urban Vehicles

1991-02-01
910255
Natural gas has been the subject of growing interest as a low emissions alternative to conventional automotive engine fuels. The development of a control system for a very low emissions heavy-duty natural gas engine is described. The engine is intended for city bus applications, with emissions targets set well within US 1994 levels. The engine uses a stoichiometric air-fuel mixture with exhaust gas recirculation and a three-way catalyst. The control system was implemented on a prototype hardware architecture designed to facilitate algorithm development. The control system software was constructed from a number of fundamental modules. Good steady-state and transient air-fuel ratio control was particularly important for maintaining optimum catalyst efficiency and hence minimum emissions. To achieve this, the air-fuel ratio control system used solenoid gas injectors and lambda feedback.
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

Unburnt Hydrocarbon Measurement by Means of a Surface Ionisation Detector

1991-02-01
910254
Recent studies in the USA have revealed that the catalysts (which are universally fitted to gasoline automobiles) are failing in service to an unacceptable extent. Although the reasons for the failures are not completely clear, it seems that misfiring, leading to highly exothermic reaction in the catalyst, may be responsible for the damage. Legislation is to be enacted later in this decade to address this problem by requiring on board diagnostic (OBD) systems which can measure misfire, as well as catalyst hydrocarbon (HC) conversion efficiency. Although some ideas have been suggested for the OBD requirements, no fully satisfactory sensor technology has yet appeared. This paper describes a novel hydrocarbon sensor based on a surface catalysis principle. The fundamental studies reported here have been made with the automobile application in mind. A catalytic chemi-ionisation model is proposed in order to enhance our understanding of this surface ionisation.
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

Applications of High Performance P/M Aluminum in Internal Combustion Engines

1991-02-01
910156
Powder Metallurgy (P/M) renders the possibilities to tailor material properties using rapid solidification or mechanical alloying processes totally different to the options of ingot metallurgy (I/M). For demanding applications in internal combustion engines new materials have become more important because of environmental and/or performance reasons. Weight reductions to improve the performance or reduce the consumptions and consequently the amount of exhaust gases and increase of temperatures at different locations of an engine need better aluminum materials. P/M solutions are described from the point of view of material's processing and general properties. The potential for automotive pistons is discussed with several examples.
Technical Paper

Cost Effective Finishing of Powder Forged Connecting Rods with the Fracture-Splitting-Method

1991-02-01
910157
The powder forging process closes the gap between conventional powder metallurgy and die forgings. Adequate shape of the preform and strict respect of its given volume avoids forging burrs and delivers closer tolerances. Powder Forging achieves higher density and therefore remarkably improved mechanical properties as compared to the conventional PM process. An example of application for a component with high dynamic stresses is the connecting rod. High precision and low weight tolerances already lead to less machining operations on sinterforged connecting rods than on classical forged or cast components. Using the patented KREBSÖGE fracture splitting procedure, subsequent costly machining operations become obsolete. This leads to remarkably lower investments for new machining lines and to cost savings for production.
Technical Paper

A Study of Oil Flow and Temperature in Journal Bearings

1991-02-01
910160
With the recent trend toward increased unit load in engine bearings, problems due to lack of lubrication frequently arise, especially in crankpin bearings. We have previously investigated the influence of shaft and bearing design on the oil flow using the connecting rod in actual use under alternating loads. In this paper, we investigate the critical value of oil flow at which the Fbearing temperature rises rapidly and the influence of connecting rod rigidity on the oil flow. As a result of these tests, it was discovered that the increase in bearing temperature (ΔTj) is in inverse proportion to oil flow (Qj),tests resulting in a single curve expressed by ΔTj = E1/Qj + E2, that the critical oil flow (Qc) varies according to Qc = Const. • E1, and that connecting rod rigidity greatly influences the oil flow (specifically, the greater the rigidity, the less oil).
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

Contribution of Optimum Nozzle Design to Injection Rate Control

1991-02-01
910185
The purpose of this paper is to discuss injection rate control of the nozzle for direct injection engines. This paper will focus on fuel flow analysis of the nozzle, a key component of Fuel Injection Systems (FIS). The optimum designed nozzle improves fuel flow efficiency and controls injection rate. To meet emission regulations in 1990's, FIS are required to produce higher injection pressure and injection rate control which creates better fuel spray atomization and higher utilization of air. But the higher injection pressure makes injection rate control difficult. In particular, injection rate control by needle lift traveling control is difficult because fuel flow characteristics in the nozzle change with injection pressure and needle lift. Furthermore, the forced control of needle lift results in poor fuel spray atomization.
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