Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

A Simulation System for Vehicle Dynamics Control

1991-02-01
910240
A simulation system has been developed to facilitate the analysis of vehicle dynamics control systems (e.g., ABS, 4WS, active suspension, etc.). This system can analyze the controllability of a vehicle model when combined with a controller. Its main features are: 1. The ability to simulate the various motions of a vehicle, utilizing a vehicle model that has been adjusted for the purpose. 2. All operations, from data preparation to final analysis, can be done easily and efficiently.
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

Real Time Vehicle Dynamics Simulation: Enabling Tool for Fundamental Human Factors Research

1991-02-01
910237
A summary is given of the enabling technologies for real time high fidelity vehicle dynamics simulation. Methods of utilizing this technology to increase realism in an operator in the loop simulation are then discussed. Finally some of the research that can be performed using a high fidelity, highly realistic operator in the loop simulator is presented. Automotive engineers have long used sophisticated, batch job computer simulations of the dynamics of vehicles and vehicle subsystems to aid them in improving vehicle performance and safety. Recent technological advances have brought high-fidelity vehicle dynamics simulation into a new realm; that of real time.
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

Characteristics Influencing Ground Vehicle Lateral/Directional Dynamic Stability

1991-02-01
910234
Lateral/directional dynamics involve vehicle yawing, rolling and lateral translation motions and dynamic stability concerns directional behavior (i.e. spinout) and rollover. Previous research has considered field test and computer simulation methods and results concerning lateral/directional stability. This paper summarizes measurements and simulation analysis of a wide range of vehicles regarding directional and rollover stability. Directional stability is noted to be strongly influenced by lateral load transfer distribution (LTD) between the front and rear axles LTD influences tire side force saturation properties, and should be set up so that side forces at the rear axle do not saturate before the front axle under hard maneuvering conditions in order to avoid limit oversteer and spinout.
Technical Paper

Simulation of Multibody Systems for the Computer-Aided Design of Vehicle Dynamic Controls

1991-02-01
910236
Simulation of mutlibody systems (MBS) that are suitable for the design of their controls require fast processing and access to advanced computational analysis tools. The approach that some MBS simulation programs take is to supply FORTRAN subroutines that represent simple transfer functions. The approach of other programs is to derive the state space description of the MBS and write it in a disc file that can be used by specialized control systems design programs. Both approaches limit the interactive process necessary for the efficient design of control systems. This paper describes a structured and modular multiport approach to the computer-aided simulation of multibody systems. The approach presented in this paper produces models of multibody systems that are not only suitable for the interactive design and evaluation of control strategies, but also suitable for processing on parallel computers.
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

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

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

The Role of Fatigue Analysis in the Vehicle Test Simulation Laboratory

1991-02-01
910166
Simulation technology for use in full or partial vehicle testing was developed in the 1970s. It requires meticulous multiaxial control coupled with the playback of frequency compensated realtime data. Simulation testing provides a virtual reproduction of actual service data, typically within 2% accuracy of load amplitudes. Use of this technology in automotive development became widespread in the 1980s. Recent advances have made simulation practical even on the component level, complementing more traditional testing techniques including simple playback, block loading and constant amplitude mechanical testing. As simulation technology has spread through the ground vehicle industry, so has the use of fatigue technology as a tool for data evaluation. This paper discusses the role of fatigue analysis in simulation testing, as well as its use for integrating simulation with more conventional forms of durability testing frequently used for evaluation of individual components.
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.
Technical Paper

Analysis and Development of A Real-Time Control Methodology in Resistance Spot Welding

1991-02-01
910191
The single-parameter, in-process monitor and automatic control systems for the resistance spot welding process have been studied by many investigators. Some of these have already been commercialized and used by sheet metal fabricators. These control systems operate primarily on one of the three process parameters: maximum voltage or voltage drop, dynamic resistance, or thermal expansion between electrodes during nugget formation. Control systems based on voltage or dynamic resistance have been successfully implemented for industrial applications. A great amount of experience on these two control methods has been accumulated through trial-and-error approaches. The expansion-based control system is not commonly utilized due to lack of experience and understanding of the process. Since the expansion displacement between electrodes during welding responds directly to the weld nugget formation, this control parameter provides a better means to produce more precise spot welds.
Technical Paper

Flow and Combustion in a Hydra Direct-Injection Diesel Engine

1991-02-01
910177
Measurements of flow, spray, combustion and performance characteristics are reported for a Hydra direct-injection diesel, based on the Ford 2.5 L, engine and equipped with a variable-swirl port, a unit fuel injector and optical access through the liner and piston. The results provide links between the pre-combustion and combustion flow and, at the same time, between purpose-built single-cylinder optical engines and multi-cylinder production engines of nearly identical combustion chamber geometry. In particular, the spray penetration was found to depend on engine speed, rather than load, with velocities up to around 260 m/s at atmospheric pressure and temperature which are reduced by a factor of 2.5 under operating conditions and seem to be unaffected by swirl. The duration of combustion was reduced with increasing swirl and ignition delay increased linearly with engine speed.
Technical Paper

A Study of Diesel Cold Starting using both Cycle Analysis and Multidimensional Calculations

1991-02-01
910180
The physical in-cylinder processes and ignition during cold starting have been studied using computational models, with particular attention to the influences of blowby, heat transfer during the compression stroke, spray development, vaporization and fuel/air mixture formation and ignition. Two different modeling approaches were used. A thermodynamic zero dimensional cycle analysis program in which the fuel injection effects were not modeled, was used to determine overall and gas exchange effects. The three-dimensional KIVA-II code was used to determine details of the closed cycle events, with modified atomization, blowby and spray/wall impingement models, and a simplified model for ignition. The calculations were used to obtain an understanding of the cold starting process and to identify practical methods for improving cold starting of direct injection diesel engines.
Technical Paper

Combined Air-Oil Cooling of the Cylinder with Oil Channel

1991-02-01
910201
The problem of a combined air-oil cooled cylinder in an air cooled motor is discussed in this paper. This method has been selected due to unequal Thermal load on the upper cylinder part. The data of previous research on oil cooling show that in spite of local overheating, oil is neither foaming nor aging. In spite of oil viscosity, heat transfer is sufficient. With encreased load - with higher temperature of cooled surfaces, the heat transfer is increasing due to two influences: increased temperature difference and better convective conditions at lower oil viscosity. The consequence is a satisfactory self-regulating effect on the cooling system; where there is locally increased heat load, the efficiency of cooling is increased too. The experimental system is described and the results of the experiments on air cooled cylinders with oil channel are given. It is characteristic of the oil flow in the channel that it is Within the range of forced laminar and forced turbulent flow.
Technical Paper

Applying Variation Simulation Analysis to 2-D Problems

1991-02-01
910210
Variation simulation analysis is a technology that has achieved broad popularity in the automobile, appliance, electrical machinery and other industries as a method of predicting and analyzing manufacturing variation due to tolerances of individual components and assembly operations. The technology is widely considered to be the only method to accurately analyze three dimensional variation problems. Recently, a substantial body of work has been developed which indicates that variation simulation analysis can provide major advantages over traditional methods even on two dimensional problems. Variation simulation analysis uses the Monte Carlo method to accurately simulate the effects of each individual tolerance distribution and complex relationships between individual tolerances can be defined.
Technical Paper

Advanced High-Temperature Test Methods for Gasket Materials, 1991

1991-02-01
910204
Equipment and techniques for evaluating the stability, creep, and sealability of gasket facing materials at high temperatures are presented. Mathematical models for predicting long-term failure of elastomer-bonded gaskets from short-term high-temperature tests were used. The value of differential thermal analyses and differential scanning calorimetry in the ranking of facing compositions and alternatives to engine testing to establish confidence in screening gasketing materials are the projects presented.
Technical Paper

Reduction of Vehicle Interior Noise Using Structural-Acoustic Sensitivity Analysis Methods

1991-02-01
910208
Since interior noise has a strong effect on vehicle salability, it is particularly important to be able to estimate noise levels accurately by means of simulation at the design stage. The use of sensitivity analysis makes it easy to determine how the analytical model should be modified or the structure optimized for the purpose of reducting vibration and noise of the structural-acoustic systems. The present work focused on a structural-acoustic coupling problem. As the coefficient matrices of a coupled structural-acoustic system are not symmetrical, the conventional orthogonality conditions obtained in structural dynamics generally do not hold true for the coupled system. To overcome this problem, the orthogonality and normalization conditions of a coupled system were derived by us. In this paper, our sensitivity analysis methods are applied to an interior noise problem of a cabin model.
Technical Paper

Physical Mechanisms for the Local Heat Transfer Enhancement Caused by Fin-Like Obstacles in Heat Exchanger Flow Passages

1991-02-01
910196
Experiments were performed to determine the physical mechanisms for the local heat transfer enhancement caused by short fins of square planform cross section, mounted on one wall of a rectangular water channel. Local heat transfer coefficients and pressure drops were measured in an array of thirty fins. Inline as well as staggered arrays were investigated. The geometry of the individual fins was held constant, while the spacing between fins, the height of the flow channel, and the Reynolds number of the flow were varied, and their effect on heat transfer enhancement determined. Flow visualization was performed using laser sheet-illuminated hydrogen bubbles, and velocity measurements were obtained using laser-Doppler velocimetry. The hydrodynamic mechanisms that enhance mixing in the flow, and hence heat transfer from the fins, were identified.
Technical Paper

A Mechanically Bonded AKG-ML 3-Aluminum Radiator as a Direct Replacement for Brazed Units

1991-02-01
910198
A new mechanically bonded aluminum automotive radiator, designated AKG-ML 3 featuring extruded extremely flat oval tubes has been developed that achieves performance levels comparable with those of ordinary brazed radiators but at a more favorable price. Also, when compared with the old mechanically assembled radiator with round tubes, the AKG-ML 3 has substantially higher heat transfer performance. The need for more efficient radiators means that the potential danger to the environment is increased substantially since the majority of more efficient radiators are of the brazed design. The low-cost mechanically bonded AKG-ML 3 certainly appears to be a way out of this dilemma.
X