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A new numerical simulation system has been developed which predicts flow behavior of fuel film formed on intake port and combustion chamber walls of gasoline engines. The system consists of a film flow model employing film thickness as a dependent variable, an air flow model, and a fuel spray model. The system can analyze fuel film flow formed on any arbitrary three-dimensional configuration. Fuel film flow formed under a condition of continuous intermittent fuel injection and steady-state air flow was calculated, and comparison with experimental data showed the system possessing ability of qualitative prediction.

The electronically-governed diesel distributor injection pump, with the proven sleeve control of injection quantity, has been in production at Bosch since 1987. Long-term development resulted in a solenoid-valve controlled injection pump. The function and component assemblies, consisting of the injection pump, solenoid valve and control unit, provide an even more flexible injection system. Of particular advantage with this type of system are the high dynamics of the fuel quantity, matching of each individual injection and the exact pump-specific fuel quantity compensation at numerous map points. Further advantages are the selection of timing and fuel injection rate independent of each other, as well as the ability to provide the correct timing even at cranking speeds. The entire system, with emphasis on the injection pump and the solenoid valve, are described for IDI engines in this paper.

A simple analytic relationship between fuel economy, vehicle parameters and driving cycle characteristics is established. Using publically available information on vehicle characteristics, the model can be used to predict fuel economy with an accuracy of about 5% (standard deviation). The model is based on two approximations: 1) an engine map approximation, and 2) an approximation for tractive energy. This paper emphasizes the second approximation, especially the energy consumed by the brakes. The model reveals the structure of fuel use in a way difficult to achieve with case-by-case numerical results and it enables study of fuel use in modified driving cycles.

The characteristics of a thermal mass airflow sensor are typically reported as response time, or the time delay measured when responding to a step change in airflow rate. However, these measurements do not provide an accurate description of the dynamics that are used to predict system performance. Experimental time response is also difficult to measure and interpret. A number of problems arise in this including difficulty in creating a controlled step change in airflow, effects of flow rate on response time, and non-linear response to mass flow. In order to better explain the dynamic response of the air meter, a frequency domain approach proves useful. A simple model of the meter is a low pass filter with a cut-off frequency determined by the mass airflow rate and the frequency response. When this is combined with a normal static transfer function of mass flow to voltage, the mass airflow sensor is completely characterized.

A prototype multipoint fuel injection system which utilises fluidic injection devices as fuel injectors for spark ignition engines is described in this paper. The unique fluidic injector unit combines four no-moving-part, monostable fluidic devices controlled by a solenoid valve interface and air-fuel mixing nozzles for well atomised air-fuel mixture. The design philosophy and operating characteristics of the novel integrated fluidic injector unit for engine applications are discussed in details in this paper. The initial engine tests on this fluidic injection system show that it provides an extended lean limit of the air/fuel mixture (by 2.2 air/fuel ratio), 7% improvement in fuel economy and 10% reduction in HC emissions compared with a base line carburetted system. These results confirmed that the use of the fluidic fuel injection system resulted in improved fuel distribution, better air/fuel mixture preparation and faster flame propagation speed.

The effect of fuel injection atomization on engine performance has been known to improve fuel economy and to reduce emissions. Hitachi America, Ltd. Research and Development along with Hitachi Research Laboratory in Japan have studied the effects and the operation of the air assist injection system which was developed and studied to help meet future Low Emission Vehicles (LEV) regulations and also Ultra Low Emission Vehicles (ULEV) regulations. The system consisted of newly designed air assist injectors having a spray angle of 15° at 170 kPa (absolute air pressure) with 370 kPa (absolute fuel pressure). The air assist injector generates highly atomized fuel droplets by swirling the fuel clockwise and the air counterclockwise. The fuel and air flowing in opposite directions collide, thereby producing particles around 30 μm in size at 274 kPa air pressure. These characteristics improve cold start, cold coolant conditions and fully warm engine conditions.

In order to improve the atomization capability of a standard port fuel injector, an optimized suggestion for an air shrouded injector is presented. The fluid dynamic part of the retained solution is composed of a special flat seat design for the fuel metering function combined with a post atomization adapter enabling both mono- and multi-spray modes. The concept works equally well in natural manifold gradient mode and with an external pressure pump. The realized concept is tested in both free jet experiments and on two different 2 litre engines, one operated in stoechiometric conditions the other in lean-burn conditions. The experimental work confirms a potential of the concept to increase torque stability and thereby lean-burn limits, decrease required spark advance and enable open inlet valve injection and consequently decrease wall wetting phenomena.

Designers are under increasing pressure to provide powertrain systems which meet tougher market and legislative requirements for:- performance, emissions and economy reliability and durability noise and refinement To meet increasing competition, powertrain products need to be “fast to market and right first time”. This implies the evolution of existing technology, comprising multi cylinder reciprocating engines and gear transmissions, drawing on a database of decades of powerplant design experience. It is with this background that CAE has proven engineering value supporting key areas of powertrain engineering to meet these technological challenges in a cost effective and timely manner. This paper follows the analytical engineering of a four cylinder engine crankshaft from concept to production design. Particular emphasis is placed on the integration of concept design software tools and the combination of finite element analysis and dynamic models with reduced degrees of freedom.

This paper presents a technique for the improvement of the idle stability on a spark ignition engine through the adaptive control of the individual cylinder ignition timing. In many causes that affect the idle stability, the difference in the torque production between cylinders has been a matter of concern. The engine speed has been sampled 220 times per a cycle and the average angular acceleration has been calculated from it. In this research, the average angular acceleration has been characterized by nonuniform torque production among cylinders. The control system has been designed to keep the average angular acceleration constant.

This paper reviews the progress made since the last SAE Congress in the development and testing of the Collins Scotch Yoke crankshaft technology and the demonstrator engine in which it is being proven. New packaging refinements are illustrated, and more detailed internal friction loss data are shown. New fuel consumption data are shown to confirm the low internal friction losses of the demonstrator engine. A study of the potential of supercharging illustrates the power increase that can be achieved with virtually no increase in engine packaging volume. A discussion is also provided of the unique, exact engine balancing that is possible with the scotch yoke technology, due to the pure sinusoidal motion of the pistons and con rods. Finally, a brief discussion is provided of the small crevice volumes that may be achieved with the Collins Scotch yoke technology.

A newly designed opposed free piston internal combustion hydraulic power generator is proposed in this paper. The pressure of the hydraulic power output of the proposed hydraulic power generator is substantially constant and the hydraulic flow rate is variable. The frequency of free piston changes from zero to maximum in response to the hydraulic flow rate and each gas cycle is always performed under an optimum working condition independent of the power output. If the proposed hydraulic power generator is combined with a variable displacement hydraulic motor, it will be possible to obtain excellent torque-speed characteristic, easy operation, and superior fuel economy. A fundamental test apparatus was constructed and tested in this work. The test apparatus uses an opposed free piston, two stroke cycle, direct fuel injection, and compression ignition engine.

Multidimensional computations were made of combustion of natural gas engine via the KIVA-II code to evaluate the combustion and emission characteristics. In the combustion submodel, a two-step kinetic reaction mechanism is employed to account for oxidation of methane. The first of the two global rate equations controls the disappearance of methane, and the second, the oxidation of carbon monoxide. Four types of combustion chamber and a two-spark-plug geometry are considered to achieve quick flame propagation of the lean air-methane mixture. The effect of spark plug locations on the combustion processes is discussed. The calculated results show that the more effective burning process with lower NOx emission could be achieved by proper design of the geometry of the piston bowl and the arrangement of the spark plug by matching of the flame front development with the in-cylinder gas flow.

The emission characteristics of a fleet of five dual fueled trucks are reported. Detailed emission data of CO, THC and NOx are presented at various modes of operation. In most cases, the CO and NOx concentrations are lower for engines using compressed natural gas. The THC emission is lower for engines fueled with gasoline. The concentration of all emitted species increases with truck mileage driven. The catalytic converter is less effective for natural gas operation.

Headliners are large parts that must be lightweight, sound absorbent and sturdy enough to carry a complement of other interior components as well. And as the dashboard becomes loaded with more and more technologies, there is a drive to spread some of that complexity over the rest of the interior of the car. Automotive headliners offer an opportunity for slashing vehicle production costs by integrating components and functions in a one-step operation. The headliner is the ideal candidate not only to accept sun visors, lighting systems and hand grips, but also garage door openers, cellular telephones and audio speakers. This paper will discuss the use of low pressure injection molding as a way to reduce headliner production costs while expanding functionality. It will also examine the equipment requirements and the implications of this process for designers and manufacturers of vehicle headliners.

Accurate, high-quality trimming is critical in the manufacture of automotive headliners. And as a wide variety of headliners are trimmed with various patterns, flexibility is essential. The method of cutting headliners with a high-velocity, ultrahigh-pressure stream of water attached to a robot offers not only flexibility, but also competitive process times, clean, non-compressed cuts and no harmful fumes. In the life of a headliner, it is not uncommon to have hundreds of engineering changes. Before water jet cutting, these changes were handled by retooling cutting dies, which requires weeks of work and costs thousands of dollars. Robotic waterjet cutting can accommodate these changes in a matter of hours by simply reprogramming the robot. When robotic waterjet cutting was introduced, it was typical for a system to cost as much as $350,000 to $500,000.

The advantages of ventilating the passenger space via a headliner are known and proven. This paper presents a practical solution for an air-condition-headliner for the VW T 4 minibus in two versions: an injection molded channel-version with additional heat insulation and a chamber-version, made using the headliner-PU sandwich material. In both cases the air channeling components are glued on the reverse side of the actual headliner; the reverse side of the headliner therefore acts as an air channelling component. The design principles, the air channelling concepts and the assembly of the two versions are discussed. The entire modular headliner is fastened to the body using clips. Since the headliner sandwich material must be adapted to provide the additional special properties of an air channelling component, the structure and production of the panel material is described for a continuous PU foam process.

The van-type truck is frequently equipped with an air deflector to reduce fuel consumption. When studying the shape of the air deflector, it is necessary to choose a shape that is less sensitive to yaw characteristics. Side wind induced yaw conditions are more typical of on-road usage. In this study, the basic characteristics for a shape with strong yaw sensitivity were first examined. Subsequently, an angle change test was carried out by replacing the space over the cab with a rectangular parallelopiped and letting the upper and side edges, just in front of the rear body be the reference lines. The yaw angle was varied between 0°, 5°, and 10°. From this result, the existence of the optimum upper and side incident angles was confirmed. Furthermore, the reduction in fuel consumption using the optimum shape as compared with the conventional shape was estimated by simulation.

The present paper reveals the design concept as well as results of experimental investigations, which were conducted in the early design stage of the planned AUDI Aero-Acoustic Wind Tunnel. This low-noise open-jet facility, featuring a nozzle exit area of 11 m2 and a top speed of approximately 60 m/s, enables aerodynamic as well as acoustic testing of both, full-scale and model-scale ground vehicles. Ground simulation is provided by means of a moving-belt rig. The surrounding plenum is designed as a semi-anechoic chamber to simulate acoustic free-field conditions around the vehicle. Fan noise will be attenuated below the noise level of the open jet. The work reported herein, comprises 1/8-scale pilot-tunnel experiments of aerodynamic and acoustic configurations which were carried out at the University of Darmstadt.