Automotive Interior Injection Molded Parts Using Microcellular Foaming Technology

<div class="section abstract"><div class="htmlview paragraph">The microcellular foam injection molding process is being widely applied by the thermoplastics industry. This process consists in a melted polymer injection mixed with a processing solvent, that is an inert gas in the supercritical state, usually CO<sub>2</sub> or N<sub>2</sub> producing a microcellular foam. This technique offers many advantages such as weight reduction, dimensional uniformization and less warpage. Besides that, it offers a satisfactory property like acoustic and thermal insulation. On the other hand, the parts from this process have an inferior mechanical property like ductility and toughness if compared with solid injection molded parts. Nevertheless, the main issue for this process is the poor appearance quality. This paper presents a review of some existing methods for surface quality improvement as Co-injection process, where a skin is injected over the microcellular part, and Heat & Cool that consists in a control of mold temperature. All the processes addressed were effective in the surface quality improvement. However, the produced parts through this method have a higher added value due some modifications done in the equipment.</div></div>

<div class="section abstract"><div class="htmlview paragraph">To explore the production and oxidation characteristics of soot in the flame of diesel jet under the condition equivalent to the direct injection diesel engine condition, the effect of three different important parameters (including injection pressure, injection duration, and oxygen concentration) are experimentally examined. For these purposes, a small CVCC (constant volume combustion chamber) with the volume of 60cc equivalent to the volume of combustion chamber of automotive diesel engine is used.</div><div class="htmlview paragraph">To obtain the experimental data of soot production and oxidation, in experiments, the ambient condition of temperature, pressure and oxygen concentration before injection timing are prepared by the combustion of lean hydrogen mixture (with help of 8 spark plugs) at a high temperature and pressure condition around 1000K and 4.5MPa. The common rail type injector with 8 injection holes for modern diesel engine is attached to this vessel. Injection pressures are set up at 80, 100, and 120 MPa. The effects of three important factors are analyzed including: (1) different injection pressures with constant injection mass; (2) different injection pressures with constant injection duration; (3) oxygen concentrations of 21% and 17% in volume. The optical window is attached on one side of this vessel and the full image of the spray flames can be visualized and recorded through this window by a high-speed color video camera. From the visualized color image of diesel flame, the flame temperature and the amount of soot inside the flame can be quantified by the two color method. This method is based on the theoretical principle that the light emission from the soot cloud is a thermal radiation of gray body which is a function of soot temperature and the KL factor, an index of the amount of soot.</div><div class="htmlview paragraph">The obtained results show that the injection duration and the injection rate are the dominant factors for heat release rate (HRR). On the contrary, within the experimental condition, the heat release rate is affected by both of the injection pressure and the oxygen concentration of ambient mainly at late combustion phase. The injection pressure and the injection duration give small effect on the level of flame temperature; however, the ambient oxygen concentration gives a large effect on the flame temperature.</div><div class="htmlview paragraph">Concerning the soot production and oxidation, all of the considered parameters have large effect. The interesting result is that the effect of injection pressure and ambient oxygen concentration on the maximum value of total KL factor is not so large. However, the soot production rate becomes lower as the decrease of injection pressure and as the decrease of ambient oxygen concentration, and results in the delayed arrival of the maximum total KL factor. Comparing with the HRR curve, it is revealed that the soot oxidation reaction is occurred under the very low HRR combustion in the case of low injection pressure and oxygen concentration condition.</div></div>

<div class="section abstract"><div class="htmlview paragraph">There is an ever growing demand for blind fastener in the aerospace industry. This demand is driven not only by the advantages of single sided installation, but also by the potential to fully automate their installation process.</div><div class="htmlview paragraph">Blind fasteners can easily be integrated with innovative end-effectors that combine drilling, installation and inspection systems, enabling the reduction of process cycle times and their associated cost savings.</div><div class="htmlview paragraph">Clearly the advantages of single sided installation are a key benefit, but it cannot be forgotten that currently the mechanical performance of these systems is reduced compared with conventional threaded or swaged parallel shank fasteners. There are other important drawbacks existing around them which could penalise significantly the optimised design and performance of the structures.</div><div class="htmlview paragraph">Specific key characteristics that take into account some of these drawbacks have been established by Airbus which will be referenced in this paper.</div><div class="htmlview paragraph">Recently some improvements in new system concepts based on the typical pull and threaded type versions have been achieved by the main aerospace fastener suppliers, based on better mechanical performance, improved cosmetic appearance of the fastener head, etc.</div><div class="htmlview paragraph">This paper will give a global view of the characteristics that are considered more important for evaluation of the next generation of blind systems to allow their optimised implementation on new applications as well as a chance to view some new systems developed by the Suppliers.</div></div>

<div class="htmlview paragraph">The application of Computer-Aided Engineering is accelerating product design, process design, and prototype development for conversion of suspension steel fabrications to aluminum castings. Development cycle-time reduction is achieved by sharing a consistent CAE model among the system designers, component designers, and process development engineers.</div> <div class="htmlview paragraph">The CAE tools being utilized include Solid Modeling tools for geometry definition and manipulation, linear FEA for evaluating strength and stiffness, and non-linear heat-transfer for modeling the casting solidification. One of the major breakthroughs in cycle-time reduction for the CAE efforts is the utilization of automatic mesh-generation technology.</div> <div class="htmlview paragraph">The component geometry is simultaneously developed by product and casting engineers, so that the manufacturability issues are addressed up-front. Preliminary stress and solidification FEA are conducted in parallel to generate a more optimal geometry. This same geometric model is later used to create Laminated Object Model (LOM) Rapid prototypes. The tooling for the prototype sand-castings is produced from the LOM.</div> <div class="htmlview paragraph">Early prototypes are produced as sand-castings, allowing shortest possible lead-times, and permitting the maximum possible time for design optimization through Finite Element Analysis.</div> <div class="htmlview paragraph">Examples of successful aluminum conversions, and the tools and technologies enabling these successes, as well as lessons learned are presented.</div>

<div class="section abstract"><div class="htmlview paragraph">An experimental study on effects of high-pressure injections in conjunction with split fuel injections were conducted on an AVL single cylinder DI diesel engine. Various injection schemes were studied through the use of an electronically controlled, common rail injection system capable of injection pressures up to 200 MPa and a maximum of six injections per combustion event.</div><div class="htmlview paragraph">Up to 100 MPa of the fuel injection pressure, the higher injection pressures create faster combustion rates that result in the higher in-cylinder gas temperatures as compared to conventional low-pressure fuel injection systems. When applying high-pressure injections, particulate emission reductions of up to 50% were observed with no change in hydrocarbon emissions, reductions of CO emissions and only slightly higher NOx emissions.</div><div class="htmlview paragraph">Over 100 MPa, on the other hand, the higher injection pressures still reduced up to almost zero-level of particulate emission, at the same time that the NO emission is reduced greatly. Under these high-pressure injection conditions, strong correlations between soot and CO emissions were observed, which compete for the oxidizing OH species.</div><div class="htmlview paragraph">Multiple or split high-pressure injections also investigated as a means to decrease particulate emissions. As a result, a four-split injection strategy resulted in a 55% reduction in particulates and with little or no penalty on NOx emissions. The high pressure split injection strategy with EGR was more effective in reducing particulate and CO emissions simultaneously.</div></div>

<div class="section abstract"><div class="htmlview paragraph">A gasoline compression-ignition combustion system is being developed for full-time operation over the speed-load map. Low-temperature combustion was achieved using multiple late injection (MLI), intake boost, and moderate EGR for high efficiency, low NOx, and low particulate emissions. The relatively long ignition delay and high volatility of RON 91 pump gasoline combined with an advanced injection system and variable valve actuation provided controlled mixture stratification for low combustion noise.</div><div class="htmlview paragraph">Tests were conducted on a single-cylinder research engine. Design of Experiments and response surface models were used to evaluate injection strategies, injector designs, and various valve lift profiles across the speed-load operating range. At light loads, an exhaust rebreathing strategy was used to promote autoignition and maintain exhaust temperatures. At medium loads, a triple injection strategy produced the best results with high thermal efficiency. Detailed heat release analysis indicated that heat losses were significantly reduced. At higher loads, a late-intake-valve-closing strategy was used to reduce the effective compression ratio. For all tests, intake air temperature was 50 C.</div><div class="htmlview paragraph">3D CFD simulations of fuel injection, mixing, and combustion were important to understand the emissions formation processes. With multiple late injections and low-to-moderate fuel pressure, spray penetration was low, mixing was fast, and wall wetting could be avoided. Fuel sprays were characterized in a spray chamber. Injection rate was measured using a rate tube.</div><div class="htmlview paragraph">Results showed that ISFC was very low. Minimum ISFC of 181 g/kWh was measured at 2000 rpm-11 bar IMEP. For IMEP from 2 to 18 bar, engine-out NOx and PM emissions were below targets of 0.2 g/kWh and 0.1 FSN, respectively, indicating that aftertreatment for these species may be reduced or eliminated. It was found that combustion noise levels, characterized by several noise metrics, could be effectively controlled by the injection process. Measurements of exhaust particulate size distribution indicated very low particle count, especially for a preferred injector with low levels of in-cylinder swirl.</div><div class="htmlview paragraph">Collectively, these results demonstrate the potential feasibility of full-time GDCI using RON 91 gasoline at low-to-moderate injection pressures with high fuel efficiency. While more development work is needed, there is good potential for a practical GDCI powertrain system based on these concepts.</div></div>

<div class="htmlview paragraph">One of the most vital factors in combustion control is Air-to-Fuel Ratio (AFR) control and estimation. Various parameters such as intake air mass flow rate, fuel injection quantity and (Exhaust Gas Recirculation) EGR flow rate are affecting the AFR magnitude. In this study a detailed mathematical, nonlinear and control oriented model of dynamic processes of turbocharged diesel engines is presented for the purpose of AFR control. It is an attempt to describe the two main subsystems of compression ignition engines called intake manifold and fuel injection systems.</div> <div class="htmlview paragraph">The intake model itself consists of compressor, intercooler, intake manifold, EGR circuit, valve section and cylinder subsystems. This model has been developed for study of the air intake system in a turbocharged diesel engine, using physical equations. Experimental data has also been used to adjust the model. The output variable of this submodel (air mass flow) is a significant parameter in calculations of engine power, emission and AFR control. Of the methods of assisted aspiration, the exhaust gas driven turbocharger is by far the most widely used. Varying the rate of gas flow through the turbine by means of Variable Geometry Turbine (VGT) is a method by which the exhaust gas flow through turbine can be limited at high engine speeds. Therefore, turbocompound in this model is considered to have VGT.</div> <div class="htmlview paragraph">Common Rail Injection (CRI) that is a fully flexible fuel injection system in which quantity, timing and pressure of injection are controllable (based on electronic control) separately is chosen in this study. Fuel injection system is comprised of solenoid, working chamber and needle subsystems. A one-dimensional, transient and compressible flow model of CRI, based on Kirchhoff's law, mass and momentum conservation equations and the equilibrium of forces is derived.</div> <div class="htmlview paragraph">AFR control of diesel engine is performed make use of fuzzy logic methodology. Fuzzy logic is a control structure which emulates the way humans arrive at decisions, given a certain set of circumstances. This method improves the control and simplifies the development process. The fuzzy logic controller achieves this by considerably reduced complexity and lack of tedious mathematical derivation associated with modern control theory methods.</div> <div class="htmlview paragraph">All above-mentioned models are programmed in Matlab/Simulink software environment. The simulation results are then compared with available data to check the accuracy of the model.</div>

The results of computer modelling of an injection moulding process with microcellular foaming (MuCell®) were presented in this work. The process is based on the dissolving nitrogen in a liquid polymer which is possible when nitrogen is in supercritical fluid state (SCF). After pressure drop of the melt in the injection mould the intensive nucleation of pores occurs and, as the result, the material with high concentration of small pores is created. The pores obtained in this way are of much smaller size than in a conventional foaming process. The pore size in the cross-section of an exemplary injection moulded part was calculated in the computer modelling and compared to the results of microscopical investigation made on the real injection moulded part. It was found that the size of the pores depends on the flow length inside the injection mould and on the position in the part’s cross-section.

<div class="section abstract"><div class="htmlview paragraph">Natural luminosity (NL) and chemiluminescence (CL) imaging diagnostics are employed to investigate fuel-property effects on mixing-controlled combustion, using select research fuels-a #2 ultra-low sulfur emissions-certification diesel fuel (CF) and four of the Fuels for Advanced Combustion Engines (FACE) diesel fuels (F1, F2, F6, and F8)-that varied in cetane number (CN), distillation characteristics, and aromatic content. The experiments were performed in a single-cylinder heavy-duty optical compression-ignition (CI) engine at two injection pressures, three dilution levels, and constant start-of-combustion timing.</div><div class="htmlview paragraph">If the experimental results are analyzed only in the context of the FACE fuel design parameters, CN had the largest effect on emissions and efficiency. Low-CN fuels had higher indicated specific nitrogen oxides (ISNO<sub>x</sub>) emissions, but up to 9 and 33 times lower smoke emissions, ∼ 0.01 filter smoke number (FSN), at 80 MPa and 180 MPa injection pressure, respectively, independent of intake oxygen concentration, relative to the high-CN fuels. Low-CN fuels had lower combustion efficiency due to their higher hydrocarbon and carbon monoxide emissions, but there was no clear trend regarding fuel effects on fuel-conversion efficiency. Higher aromatic content appeared to have a secondary effect on NO<sub>x</sub> and smoke emissions. There was no clear effect of 90% distillation temperature (T90) on emissions or efficiency at the operating conditions investigated in this work.</div><div class="htmlview paragraph">The results of the study indicate that neither emissions, efficiency nor operational parameters directly correlated with CN, aromatic content, or T90, independently at all operating conditions. On the other hand, the experimental results were better explained by the ignition delay differences between the fuels. The ignition delay correlated well with the lift-off length, H, at a constant injection pressure independent of the charge dilution. The corresponding equivalence ratio at the lift-off length, ϕ(H), affected the chemical reactions downstream of H and production of the fuel-rich partially reacted mixture inside the fuel jet. Additionally, the smoke emissions of the long-ignition-delay fuels provided further evidence that ϕ(H) below ∼ 2 results in mixing-controlled combustion that does not produce soot.</div></div>

<div class="htmlview paragraph">Visualization of in-cylinder reaction processes and performance analysis of a direct-injection Diesel engine equipped with a high injection pressure (HIP) unit were conducted. The study was directed towards evaluation of high-power-density (HPD) engine design strategies, which utilize more intake air operating at rich overall fuel-air ratios.</div> <div class="htmlview paragraph">Two separate engine apparatus were used in this study: a Cummins 903 engine and a single-cylinder optical engine equipped with the same family engine components including the cylinder head. The engines were mated with an intensifier-type HIP fuel system fabricated at Rutgers which can deliver fuel injection pressure of over 200 MPa (30,000psi).</div> <div class="htmlview paragraph">The one-of-a-kind high-speed four-band infrared (IR) imaging system was used to obtain over fifteen hundred sets of spectral digital movies under varied engine design and operating conditions for the present analysis. In order to analyze and present this large amount of results, a new data analysis and presentation method was developed (called Rutgers Animation Program, RAP for short). RAP is a computer program permitting simultaneous display of as many as twenty-eight (28) sets of digital movies over a single PC screen for mutual comparison in a controlled manner.</div> <div class="htmlview paragraph">Among the findings from the study is that the in-cylinder imaging performed within the first several cycles may not represent what is happening in a typical warm engine. In addition, the spray development and subsequent reactions of the HIP unit may not be comparable to those of low-pressure conventional injector units. In-cylinder processes and engine performance of an HPD engine affected by various factors are also described in the paper which include: the injection pressure, intake air temperature, and overall air-fuel ratio.</div>

<div class="htmlview paragraph">In-cylinder reactions of several internal combustion engine configurations were investigated using a highspeed four-spectral infrared (IR) digital imaging device. The study was conducted with a greater emphasis on the preflame processes by mutually comparing results from different engine-fuel systems.</div> <div class="htmlview paragraph">The main features of the methods employed in the study include that the present multi-spectral IR imaging system permits us to capture progressively changing radiation emitted by new species produced in-cylinder fuel-air mixtures prior to being consumed by the heat-releasing reaction fronts.</div> <div class="htmlview paragraph">The study of the Diesel or compression-ignition (CI) engine reactions was performed by varying several parameters, e.g. injection pressures, intake air temperature, fuel air ratio, and the start of injection. They were investigated also for the following mixture preparation-ignition methods: (1) direct-injection of Diesel fuel; (2) homogenous charge (fumigation) ignited by pilot injection and (3) homogeneous charge self-ignition.</div> <div class="htmlview paragraph">For the spark-ignition (SI) engine processes, the reactions were investigated using different fuels including gasoline and propane, which were introduced by either the port-fuel-injection unit or carburetor.</div> <div class="htmlview paragraph">The sequential images captured of in-cylinder preflame reactions were compared with those of the subsequent combustion reactions. In particular, they are expected to serve as an overall survey of visualizing the preflame processes in the cylinder.</div>

<div class="htmlview paragraph">This paper describes the optimization process of a small single-cylinder research HSDI diesel engine, starting from a conventional combustion towards split-injection low-temperature combustion.</div> <div class="htmlview paragraph">Targets for emissions, fuel consumption and combustion noise are defined with the characteristics of low temperature combustion in mind, in other words, high CO, HC and combustion noise but low soot and NO<sub>X</sub>.</div> <div class="htmlview paragraph">In this investigation the targets are defined for a medium-load working modes of a typical small four-cylinder turbo-charged diesel engine, equipped with a particulate trap and oxidation catalyst. They are introduced into an objective target function which is a guide for the optimization process.</div> <div class="htmlview paragraph">The statistical optimization procedure used is the method of consecutive screenings. With this methodology, six factors are optimized: mass distribution of the fuel injection pattern, injection pressure, combustion phasing, EGR rate, boost pressure and dwell time between injection events.</div> <div class="htmlview paragraph">For each consecutive screening round, a response surface of the objective target function is built which is optimized with a steepest ascent method. The optimum serves to define the next screening round. The final optimum settings are characterized by a late split-injection and a high EGR rate. The two injection events lead to two auto-ignition delay events, resulting in a highly premixed combustion. This combustion mode is characterized by very low levels of nitrogen oxides (10∼15 ppm) and low combustion noise at reasonable fuel consumption, soot, HC, and CO emission.</div>

<div class="section abstract"><div class="htmlview paragraph">The paper reports the results of an experimental investigation carried out in a prototype optically accessible compression ignition engine fuelled with different blends of commercial diesel and n-butanol. Thermodynamic analysis and exhaust gas measurements were supported by optical investigations performed through a wide optical access to the combustion chamber. UV-visible digital imaging and 2D chemiluminescence were applied to characterize the combustion process in terms of spatial and temporal occurrence of auto-ignition, flame propagation, soot and OH evolution.</div><div class="htmlview paragraph">The paper illustrates the results of the spray combustion for diesel and n-butanol-diesel blends at 20% and 40% volume fraction, exploring a single and double injection strategy (pilot+main) from a common rail multi-jet injection system. Tests were performed setting a pilot+main strategy with a fixed dwell time and different starts of injection. For the diesel case, the whole amount of injected fuel and injection pressure were set at 22 mg/str and 80 MPa corresponding to a medium load regime for an automotive light duty diesel engine. The fuel amount for the butanol-diesel blends was changed to get the same chemical energy of the delivered fuel as the reference diesel case (935J/str). The investigation was carried out at two EGR rates, 0% and 50%, corresponding to a concentration of O<sub>2</sub> at intake of 21 and 17%, respectively.</div><div class="htmlview paragraph">Taking advantages of the higher resistance to auto ignition of the butanol-diesel blends, the results showed a transition from the conventional to a partial premixed combustion for the BU40 in the single injection case. The combined effect of two-stage injection and EGR increased the ignition delay and the switch to the partial premixed combustion was enhanced. Improvement in NOx-soot trade-off was obtained activating the double injection strategy particularly with the butanol blends.</div><div class="htmlview paragraph">Optical diagnostics allowed to detect and feature the spatial distributions due to the flame luminosity and OH emission at autoignition and to estimate of the lift-off length. A high concentration of OH radicals was detected for all the test cases without EGR that corresponded to an enhanced oxidation phase and a fast soot reduction. Further, the soot oxidation phase resulted more significant for the higher butanol volume fraction in the blends.</div></div>

<div class="section abstract"><div class="htmlview paragraph">The objective of the present research was to analyze the effects of using oxygenated fuels (FAMEs or biodiesel fuels) on injected fuel spray and soot formation.</div><div class="htmlview paragraph">A 3-D numerical study which using the KIVA-3V code with modified chemical and physical models was conducted. The large-eddy simulation (LES) model and KH-RT model were used to simulate fuel spray characteristics. To predict soot formation processes, a model for predicting gas-phase polycyclic aromatic hydrocarbons (PAHs) precursor formation was coupled with a detailed phenomenological particle formation model that included soot nucleation from the precursors, surface growth/oxidation and particle coagulation.</div><div class="htmlview paragraph">The calculated liquid spray penetration results for all fuels agreed well with the measured data. The spray measurements were conducted using a constant volume chamber (CVC), which can simulate the ambient temperature and density under real engine conditions. The numerical results suggest that the liquid penetration length with methyl oleate (MO) tested as a representative of FAMEs, is longer than with diesel fuel, D100 and tends to decrease as the injection pressure is increased for all fuels.</div><div class="htmlview paragraph">In addition, the results show that the ignition delay is shorter while flame temperatures are lower with MO than with D100. With D100, a soot formation phase was observed near the injection nozzle, and soot formation was observed along the contour of the flame. In contrast, early phase soot formation was not observed with MO because oxygen in the fuel plays an important role in reducing the associated reactions and combustion temperatures.</div></div>

<div class="htmlview paragraph">To reduce the weight of the front windshield system, a fiber reinforced plastic design for the wiper arm and blade is being investigated.</div> <div class="htmlview paragraph">The use of suitable thermoplastics reinforced with short fiberglass allows the elaboration of good stiffness parts by injection moulding. Tests were carried out to show that stiffness depends on the fiberglass concentration and orientation. Likewise the temperature leads a decreasing of mechanical properties.</div> <div class="htmlview paragraph">Processing conditions of plastics have significant influence and aim to increase their performances, effectively a distribution in the orientation of fiberglass can be observed in the thermoplastic matrix. Various experimental means are used to characterise the plastic materials.</div>