Search Results

The paper describes the setup of a 4-cylinder 1.4-liter prototype Spark Ignited (SI)-engine, which is highly boosted, extremely downsized and port fuel injected. During experimental data gathering with the engine it was discovered that the originally mounted fuel injectors were non-optimized an unable to produce an expected low fuel consumption performance at low speed, low load engine working conditions. To solve this problem by finding an optimized alternative solution for the mixture preparation process it was decided to use a high-performance numerical simulation tool. The paper presents the overall layout of the prototype engine as well as the structure of the 3-D dynamic optimization tool used to address the mixture preparation problem. The paper continues with a detailed description of the different steps used to reach the complete optimization of the mixture preparation system (both the fuel injectors and the intake manifold).

The paper gives a short introduction to the bio-diesel mixture approach for diesel engines. The paper continues with a description of the design of a strategy for recognition of a random bio-diesel fraction, Bx, by a purely software-based sensing technique, which creates an image of the temporal combustion behavior and uses only sensors already in service for current common rail mixture preparation systems. A short description is made of a baseline approach of sensing technique based on the presence of a crank angle speed sensor. Hereafter the paper presents the introduction of several integral or Upper Level (UL) key-parameters used to enhance the precision of the Bx-detection or completely replace the original lower level combustion key-parameter set, which relates the instantaneous fraction of bio-diesel, Bx, to the engine torque.

The paper gives a short introduction to the notion of flex fuel approach for diesel engines. The paper continues with a description of a basic study of the diesel combustion process to allow the design of a strategy for recognition of a random bio-diesel fraction, Bx, by a purely software-based sensing technique, which creates an image of the temporal combustion behavior and uses only sensors already in service for current CR-mixture preparation systems. The paper concludes presenting a series of experimental verification data obtained on a large-scale series produced 1.3 liter Turbo-charged CR-rail passenger car engine.

The paper presents the background research on the physics of the droplet coalescence phenomena carried out by an interactive usage of high-level 3-D numerical simulation tools and high-level optical visualization and measurement techniques. The presentation continues with the description of a new injector atomizer plate layout, which enables a physical coalescence control of the droplet population within the entire fuel spray. Finally are presented examples of the impact on exhaust emissions of the introduction the new atomizer plate with coalescence control by engine test bed experiments (steady state low load conditions) and vehicle tests (first cold part of the FTP-cycle).

The success obtained by use of Virtual Engine Modeling (VEM) in the design and development areas of fuel injectors generated a lot of interest from production and quality engineers to dispose of a similar tool related to spray vessel measurements. To respond to stringent PL6/EURO5 requirements it was decided to develop a Virtual Spray Vessel (VSV) tool capable of predicting spray patters and perform droplet diameter analysis comparable to Phase Doppler Analysis (PDA) results. The paper describes the analogies between VEM and VSV modeling, the specific new numerical approaches to obtain spatial spray data comparable to conventional mechanical measurement techniques and to perform droplet diameter analysis comparable to PDA data. The paper concludes with a series of comparisons of simulated and experimental data.

The paper presents a short introduction on the evolution from the first generation of software based flex fuel sensor systems over the second system generation including new gasoline/ethanol optimized fuel injectors to the 3rd generation, which combines all available optimized mechanical components. It demonstrates that to meet the new emission regulations and On Board Diagnostic requirements a new highly flexible Electronic Control Unit (ECU) is needed. A detailed description of the new powerful, layered-structure ECU-family is given. The paper concludes with some illustrative experimental results obtained by combining the new ECU-family with engine-layout optimized mechanical components.

The paper presents the basic scientific analytical approach to identify the main physical parameters, which enable an optimization of several layouts for an Ethanol Cold Start (ECS) device. The main optimization criteria for the system layout are a single mixture preparation system for both cold start and hot engine handling, a short energy release time, a short start time and a possible high-precision ethanol metering system capability after start. The paper describes 3 suggested solutions. Two of the solutions are prototyped and tested on several vehicles. The paper concludes with a series of experimental data obtained on different flex engines with the new ECS-system variants. The obtained test results show good pure ethanol cold start capability for temperatures above 263 K and an excellent system temperature control of the fuel in the fuel-rail and in the injectors, which prevents the occurrence of any cavitations phenomenon.

The paper presents the main reasons for the increasing market share of vehicles with the capacity to run on random bio fuel blends. It explains the reason for which a single fuel supply system is mandatory in modern flex vehicles, even for cold start by pure ethanol fuelling The paper continues with an analytic research for the most appropriate device location and a detailed description of 3 suggested device layouts. The paper concludes by a presentation of a series of data obtained by real-time vehicle experiments at low ambient temperature conditions.

The paper presents the main reasons for the increasing market share of vehicles with the capacity to run on random bio fuel blends. It describes the philosophy and basic layout of current integral flex mixture preparation systems. The paper demonstrates the necessity to introduce a series of new high-performance analysis tools for further improvement of the mixture preparation system and in particular the fuel injector performance. The paper continues with a discussion of the basic structure of the interactive Virtual Engine Model approach applied to fuel injector atomizer optimization. Test results obtained by application of the new tools to two different series production flex engines are presented. The impact of the improved spray formation capability of the optimized fuel injector atomizers is explained and experimental vehicle FTP-cycle data are reported and discussed.

The paper presents a description of the development phases of the new third generation of “green” fuel injectors. The development objective for the new PICO-ECOlogical injector was to define a layout, which enables an optimal parameter configuration for both the mixture preparation (high flexibility to adapt different atomizer plate structures) and the manufacturing processes. It is demonstrated in which way the use of high-level numerical simulation and visualization techniques have become an integrated part of the development process. A detailed description is given of the new layout with respect to earlier versions and the advantageous new features obtained are discussed. Test results obtained by the new 3rd-generation injector layout are presented. The impact of the improved dynamic response capability is explained and experimental data at both engine test rig and vehicle FTP-cycle conditions are reported and discussed.

On the basis of the large amount of know-how accumulated in the field of automotive ethanol SI-engine fuelling in Brazil, it seemed appropriate to continue and set a new milestone in the usage of ethanol fuel. The paper presents the preliminary study made to enable the transfer of the ethanol technology to a 5.9-liter 4-cylinder boxer aircraft engine. The study describes the steps made to define the optimal parameter configuration for the transfer of the fuel system packaging, the fuel injector layout, the engine control unit (ECU) and the legislative redundancy requirements for aviation applications. The paper illustrates the use of numerical simulation techniques and special visualization approaches necessary to understand the physical phenomena of mixture preparation (spray atomization and momentum). Two different layouts are presented and discussed and a certain number of experimental results obtained with the retained solution are presented and discussed.

The present paper describes a study, which can enable a small displacement (1.3 liter) turbocharged European CR-diesel engine to tolerate an important increase in EGR-level. The analysis is performed by use of a 3D virtual numerical engine model, which isolates the main parameters that must be optimized within the perimeter of the combustion chamber. The paper gives a short introduction to the physical background for NOx and soot-formation as well as a recall of the main issues related to the simulation models used in the virtual engine simulation. The analysis is performed in a 9 points load/speed test matrix. Several EGR-rates are studied as well as the impact of a precise temperature control of the exhaust gas re-introduced in the intake manifold. The paper concludes by an analysis of the cumulated impact on the EGR-level tolerated by the engine after the introduction of the suggested optimization measures.

The present paper is a contribution in which is used a numerical simulation approach, the Virtual Engine Model, to study the combination of the Compression Ignition process with a Gasoline Direct Injection mixture preparation in a limited number of load-points. The first part of the paper describes the reasons for which current Gasoline Direct Injection engine technology must be combined with other technologies related to the in-cylinder mixture preparation control to further increase their potential for decreased fuel consumption. The paper continues with a description of the physics of spark and compression ignited processes as well as of the involved mixture preparation hardware components. The setup and the practical use of the Virtual Engine Model are discussed for both spark and compression ignited approaches.

The present paper describes a study of the basic parameters, which govern particulate (soot) formation within the combustion chamber of a small displacement (1.3 liter) turbocharged European CR-diesel engine. The main tools used for the study are a real fired engine, a numerical virtual engine and a special high ambient pressure vessel for injector spray visualization. The paper describes an improved soot formation model implemented in the virtual engine setup. A comparison is presented between measured and computed combustion data at 8 different load points. The paper concludes with a discussion of the means, which can be used to minimize the particulate matter formation in the design phase of both the combustion layout and the fuel injector atomizer as well as in the design of the injection control strategies.

The first part of the present paper describes the means by which the spray momentum can be decreased. The objective can be obtained either by injector-internal geometrical design changes, which very often lead to a highly non-uniform spray density/droplet distribution or by a new injector-external process, called the colliding jet (CJ) approach. The paper continues with a detailed description of the physics of the controlled secondary breakup process provided by the CJ-approach, which enables a very uniform density/droplet distribution on the downstream side of the collision zone as well as an approximately 40 % decrease in spray penetration depth. The knowledge of the physics of the CJ-approach enables the introduction of a new spray model in the 3-D numerical simulation code NCF-3D.

The paper describes the optimization to match the Brazilian market requirements for a Flex-Vehicle of the intake system and in particular the fuel injectors of a small displacement (1.6 l) 8 valves passenger car engine. The imposed target was to find a compromise for the hardware components related to the mixture preparation process, which optimize their performance with respect to a gasoline with a random content (from 0 to 100 %) of ethanol. The analytical optimization process is performed by use of a 3-D numerical virtual engine in which can be studied the physical phenomena of spray atomization, vaporization and momentum fluctuations from different injector atomizer layouts. The different atomizer layouts as well as several vaporization enhancement approaches are rated with respect to a baseline configuration on the virtual engine. The paper presents the results obtained by highest rated solutions, which were manufactured as prototypes and tested on the real engine.

The paper presents the today’s power train systems, which largely reflect a one to one mapping of physical units into a dedicated electronic control system. A new approach is suggested for a breakdown strategy with an ECU centered structure linked to a surrounding harness of sensors and actuators. Like body electronics did first, automotive graded combination of semiconductor and packaging technologies are used to develop a network of mechatronic components. This allows an easy and effective separation between the SW development at the vehicle level and an off-line optimization and calibration of components. A development project is shown for a gasoline direct injected engine, where mechatronic components (e.g. cylinder, fuel pump and injectors, valve train) are networked and controlled by a master digital core, which is the application SW restricted area of the car manufacturer.

The paper presents a study of the influence of fuel pressure supply fluctuations on the upstream side of the fuel injector atomizer. The study is performed over a wide range of pressures (70 to 130 Mpa) with two different common-rail (CR) high-pressure fuel injectors. The common atomizer is a VCO-type equipped with conically shaped atomizer bores. With the injector tip (nozzle) mounted in a counter-pressure vessel the pressure fluctuations in the fuel-rail and in the injector body are recorded simultaneously with stroboscopic Schlieren-visualization of the time-resolved spray behavior. It is demonstrated that not only the instantaneous mass flow is affected. As a function of rail-pressure, pulse-width and injection strategy the pressure fluctuations change the spray hard-core structure and its break-up behavior.

The main objective of the paper is to describe the optimization work performed to adjust direct injection (DI)-technology to SI-engines running at high (8000 to 10000 rpm.) and extremely high speeds (more than 18000 rpm). In the first category are located a certain number of small and middle displacement two-stroke series produced engines. In the second category are the typical high power racing engines used for competitions like the formula 1. The first part of the paper describes the particular requirements that an in-cylinder fuelling and mixture preparation will have to fulfill with the extremely short period available for introduction and vaporization of the fuel. The paper continues with a description of the different spray shapes, spray penetration velocities and atomization capabilities, which are optimal for the different combustion chamber architectures.

The paper presents a study of a key-element in the mixture preparation process. A typical common-rail (CR) high-pressure fuel injector was fitted with a prototype injector nozzle with atomizer bores of a particular conical layout. It is demonstrated within certain layout limits, that a considerable enhancement can be obtained for the secondary break-up of the hard-core fluid sprays produced by the nozzle. The impact on the combustion process is examined in terms of pressure and heat release as well as of the engine-out pollutant emission. The results are compared to those of an earlier developed CR high-pressure injector nozzle. The atomization behavior of the prototype nozzle is illustrated through experimental results in terms of engine-out emissions from a 1.3-liter turbo-charged passenger car diesel engine. The detailed spray behavior is visualized on a component test rig by use of specially developed optical visualization techniques.