Search Results

A computer submodel, predicting the twin-turbine discharge coefficients is presented. Gas flow through axial separated spiral volute casing into the interspace is solved with divided expansion in two convergent nozzles. Mixing taking place in the interspace is assumed to be isobaric and the gas expansion through the rotor is simulated with rotor characteristics derived from conventional turbine characteristics. The results of computation are turbine discharge coefficients and efficiency map, determining the twin-turbine boundary conditions under partial admission. The method has been validated using experimental data of 6- and 12-cylinder turbocharged diesel engines and the predictions are in good agreement.

This paper describes the principle of operation of a novel capacitance based transducer which is employed in a bench mounted turbocharger to identify oil leakage from the “piston-ring” seal at the turbine end of the shaft. Some preliminary data relating to “vacuum-to-leak” conditions are presented along with graphs which illustrate the filling of the transducer. Finally, the design modifications which will be required if the transducer is to be used for leak detection in a turbocharger mounted on a firing engine, are briefly outlined.

A method for selecting the optimum principal dimensions of a centrifugal impeller (under a specified set of constraints) is described. The proposed procedure is based on maximizing the overall isentropic efficiency for a given set of design requirements (mass flow rate and pressure ratio). Numerical optimization technique, for solving non-linear programming problems, has been used to solve a design objective function. The results have shown that a quicker and more accurate estimation of impeller overall dimensions is achieved. Furthermore, it should not be difficult to re-structure the proposed program so that the preliminary optimization of the complete stage might be carried out.

This paper describes an entry system that could be used to convey uncured sheet molding composite (SMC) into a pyrolysis system. This entry system consists of: a compression chamber, a cutting chamber, and a final temperature control chamber. This research was accomplished through a joint effort of the Eagle Picher Plastic Division and the Thayer School of Engineering, Dartmouth College on behalf of the SMCAA. Motivation for this research is the total recycling goal of all thermoset composites by the SMCAA.

Containing a mix of analog electronic, digital switching and mechanical elements, an ignition system can be considered an automotive “acid test” of simulator performance. Over the years, simulation technology has advanced to the point where various technology combinations can be accurately simulated, and interplay between the elements can be studied prior to prototype fabrication. This paper discusses the various aspects of modeling as applied to the simulation of ignition systems and offers suggestions for simulating other automotive applications.

One U.S. automotive OEM has approved use of a composite filler produced from recycled SMC parts for the current 1993 model year molded SMC production components. Two other U.S. OEMs have approval programs under way for use of composite filler in production parts. The reground and milled SMC (composite filler) is produced using techniques developed over the past two years by several molders and supplier member companies of the SMC Automotive Alliance (SMCAA). A program was developed in cooperation with automotive OEMs for evaluation and approval of the SMC composite filler for replacement of up to 20% by volume of the CaCO3 (calcium carbonate) filler (10% of total formula weight) in virgin SMC for molding of automotive production parts. Factors limiting user-levels include paste viscosity which, if too high, prevents adequate wet out of chopped glass reinforcement and void-free processing.

Hardware-in-the-loop simulation may become a standard tool for the development of electronic or mechanical automotive components. A single component or even a whole vehicle can be replaced by mathematical models simulated in real time on small and cost-effective hardware systems, while other components which need testing or are just part of the test setup, are connected to the simulation in a closed-loop configuration. Increased experience and advances in software and hardware make this technology very attractive. Typical examples demonstrate how it can not only reduce field tests, but also make formerly unfeasible experiments practical. Some of the software and hardware issues are also discussed.

This paper describes a real-time engine simulation with an engine controller in the loop. The extremely high update rates needed to interface to the controller and the many types of signals required by the controller place great demands on the interface between the engine control unit and the digital simulation of the engine. The interface used to meet these demands is a distributed processor simulation system, the Applied Dynamics Real-Time Station. The interface system and the method used to schedule the processors to execute the engine hardware-in-the-loop simulation are described in this paper.

There is a need for simulation to provide verification of an overall automotive system, with interacting components. Numerical methods for simulation in specific disciplines need to be understood and incorporated in the system-level framework. The paper surveys the state of the art for automotive subsystem simulation with emphasis on control applications.

Increasingly severe noise legislation and customer expectations for improved vehicle refinement continue to require fuel injection equipment manufacturers to reduce the noise generated by injection pumps. The measurement of injection pump noise or, more recently, sound power level has hitherto been carried out in anechoic or semi-anechoic chambers using purpose built quiet drive rigs which have themselves required continual quietening in order to allow accurate measurements to be made. The accuracy and speed of the measurements were improved some years ago with the development of the microcomputer based Lucas-CEL sound power analysis system. However, recent advances in acoustic intensity technology due to the ready availability of low-cost processing power has led to a re-evaluation of the measurement of pump sound power.

Electronics technology has made remarkable progress in recent years, and in the field of automobile noise and vibration control, it has attracted the interest of engineers due to its potential for use in the active control of vibration isolators. This report describes an investigation on reducing automobile vibration caused by engine explosion using a piezo actuator(PA) engine mount. Piezo actuator has a very high speed response but the displacement is generally very small. Therefore PA mount requires an amplitude enlargement mechanism. Here, an active mount with an enlargement mechanism incorporated was developed. For the control system, the adaptive control algorithm proposed by S. J. Elliott et al. was employed as a base, and a control rule against limitation in the power of the actuator was used in combination with it. A significant attenuation of the vibration of the dominant harmonic order in idling was achieved. The results are reported in the following pages.

A general approach for minimizing radiated acoustic power of a baffled plate excited by broad band harmonic excitation is given. The steps involve a finite element discretization for expressing acoustic power and vibration analysis, analytical design sensitivity analysis, and use of gradient-based optimization algorithms. Applications to rectangular plates and an engine cover plate are presented. Thicknesses are chosen as design variables.

This paper describes a feasibility study of the acoustic holographic method to identify a noise source on an operating vehicle. A new acoustical holography method applicable to identification of a nonstationary noise source was assessed and developed. Based on the new method, a measurement system was made and applied to quantification of the noise source in the vehicle. The method was evaluated first for source identification capablity and confirmed by loudspeakers. The experimental approach was then applied to identify the location of vehicle tire noise under various steady state conditions. In this paper, an identification method of noise sources with relatively high power level is presented and the relationship between locations of tire noise sources under various operating conditions investigated.

Relationships between radiant emissions, as measured by an in-cylinder optical sensor, and spark-ignition engine combustion parameters are presented for possible use in engine combustion diagnostics and future engine control strategies. A monochromatic gas radiation model, developed in a previous study, was used to derive a series of relationships between the measured radiant emission characteristics and several spark-ignition engine combustion parameters, such as the amplitude and phasing of the peak heat-release rate, combustion duration, IMEP, NOx emission, pressure, trapped mass and exhaust-gas temperature. In addition, many engine parameters of interest can be estimated indirectly from the radiation signal using empirical models. Correlations of air-fuel ratio and exhaust emissions are presented which contain a combination of radiant emission parameters and known base-engine operating parameters, such as intake manifold pressure, etc.

Cylinder head combustion chamber and piston temperatures and heat fluxes were measured in a 2.2 L 4 cylinder spark ignition engine. Measurements for the combustion chamber were made at wide open throttle conditions, 1400 rpm to 5000 rpm at 600 rpm increments, additional measurements were made on the combustion chamber at part throttle conditions at 3200 RPM. Piston temperature and heat flux measurements were made at WOT conditions from 1400 to 3200 RPM in 600 RPM increments. Average combustion chamber surface temperatures ranged from 130 deg. C to 248 deg. C, while peak combustion chamber surface temperatures ranged from 142 deg. C to 258 deg. C for WOT conditions. Peak heat flus at the surface for WOT conditions in the combustion chamber ranged from 1.2 MW/m2to 5.0 MW/m2. Central region heat fluxes were 2.3 to 2.8 times greater than those in the end gas regions of the combustion chamber.

Much of the design and development of the modern automobile is dedicated to protecting occupants or reducing vehicle damage during and after a crash. Although the primary function of the vehicle body structure in this respect is to dissipate the kinetic energy of the vehicle, effective protection depends upon careful management of this energy in order to achieve the optimum collapse mechanism. For conventional metal components, the art of creating such “crashworthy” performance is now well understood. However, more and more vehicles are turning to polymer-based composite materials in their structures and these exhibit a totally different type of behaviour in the way that they dissipate energy to the metals which they replace. This paper reviews the fracture mechanisms of these materials, in relation to different impact speeds, as they affect the vehicle designer.

The relationships between air flow metering and combustion control for spark ignition engines, such as engines with three way catalysts, lean NOx catalysts, two stroke engines and direct fuel injection engines were investigated. The effects of control parameters on combustion were analysed and the relationships between control parameters and air flow metering and roles of the meters in combustion control were clarified. The control strategies adaptable to many types of engines which have a wide control range of the air/fuel mass ratio are classified as (1) air quantity control,(2) fuel quantity control, and (3) exhaust gas recycle quantity control. The control parameters for the three strategies are fuel quantity, air quantity, exhaust gas recycle quantity, exhaust gas temperature, knocking, excess air factor, and mixture quality with additional parameters of swirl ratio, and spark timing for conventional spark ignition engines, two stroke engines and direct injection engines.

Postcrash fires are a frequent cause of death in otherwise survivable automobile and aircraft accidents. The idea of the ICED (Internal Circuit Emergency Disconnect) battery [1] is to eliminate electrically ignited postcrash fires by means of an inertial interrupt device that will disconnect the active circuit at the battery if an accident should happen. The design of the prototypes that were tested and the analysis of the disengagement performance will be discussed. A ballistic pendulum impact test rig was designed and used to test the prototypes. The test results and analytical values were shown to be satisfactorily close to each other.

Automotive vehicle crash safety requirements have steadily become more stringent over the last decade. Automobiles of tomorrow have to comply with a host of requirements in various crash modes in order to be considered roadworthy. In the first section of the paper, the current major requirements, some important requirements that are imminent, and desirable requirements in the near future are briefly discussed. Until recently, crash requirements have been focused mostly on the vehicle structure rather than the occupant protection, with the exception of frontal crash. Scarcity of in-depth interpretation of accident data, lack of biofidelic injury assessment devices (“crash dummies”) and the necessity for test repeatability had kept the testing procedures simple. Often, crash testing involved statically loading the vehicle to measure the structural strength, without consideration of the dynamic behavior of the structure or the structure/occupant interaction.

Demonstration projects of many Diesel Particulate Traps have been and continue to be performed. Many experimental trap systems require software customization to an individual vehicle to account for duty cycle and component variations. This level of customization is not practical in a production environment and in a marketplace where a trap system needs to function on many types of engines and duty cycles. This paper describes the production experience of the Donaldson Dual Ceramic Wall Flow Electric Regeneration Diesel Particulate Trap which has overcome specific production and durability obstacles.