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Journal Article

Development of a High Performance Natural Gas Engine with Direct Gas Injection and Variable Valve Actuation

2017-09-04
2017-24-0152
Natural gas is a promising alternative fuel for internal combustion engine application due to its low carbon content and high knock resistance. Performance of natural gas engines is further improved if direct injection, high turbocharger boost level, and variable valve actuation (VVA) are adopted. Also, relevant efficiency benefits can be obtained through downsizing. However, mixture quality resulting from direct gas injection has proven to be problematic. This work aims at developing a mono-fuel small-displacement turbocharged compressed natural gas engine with side-mounted direct injector and advanced VVA system. An injector configuration was designed in order to enhance the overall engine tumble and thus overcome low penetration.
Technical Paper

ECOCOST: A Software Tool That Makes Life Cycle Assessment Evaluations Available for the Business Decision Makers

1998-11-30
982164
The complexity of environmental problem is characterised by the typical difficulty to find an unique quantitative measure for “being green”. Environmental damage cannot easily be compared with parameters such as cost or time that are “hard” metrics. However, techniques like Life Cycle Assessment should make it possible comparing products based on the basis of their environmental profile. In this study a modelled approach that allows to integrate Life Cycle Assessment considerations within multi-criteria analysis methodology is described: this integration is clearly exemplified by a simple software tool called ECOCOST. ECOCOST represents an effort to join different field of evaluation, other than environmental, to the Life Cycle Assessment: then environmental results emerged from LCA can be matched with other kind of evaluation, economical and technical in particular.
Technical Paper

A New Methodology for Improving Accuracy of Structural Analysis of Car Body Parts

1998-09-29
982336
The Finite Element Analysis (FEA) is widely used in automotive industry for many applications, such as structural analysis, computational fluid dynamics (CFD), vibration behavior and acoustic properties, crashworthiness and, more recently, manufacturing process simulation. For all these FEA applications, accuracy is always a key issue. The analysis accuracy depends mainly on two factors: on one hand the FEA codes and on the other hand the definition of boundary conditions and material properties. Over the years, most FEA codes are well tested for accuracy through numerous benchmarks: therefore breakthroughs in further accuracy improvement from the aspect of FEA codes are difficult to achieve. On the other aspect, there is some room for FEA improvement by means of more accurate definition of material properties. In this paper, a new methodology for improving analysis accuracy by considering thickness variations of the component is proposed and validated using a structural body part.
Technical Paper

Permanent Mold Gravity Casting Cylinder Block with Hypereutectic Aluminum Liners

2001-03-05
2001-01-0402
A new category of hypereutectic aluminum liners, made by PM route is now available on the market (SILITEC) and it is successfully applied to high-pressure die casting process to produce open deck cylinder blocks. The claimed achievable engine performances over cast-iron liners (weight saving, reduction of oil consumption, optimal heat transfer, wear and friction losses reduction) justify the interest of automotive industry in developing such a technology. The paper will present the experience and the achieved results in permanent mold gravity casting with Silitec liners, where metal flow definition and temperature distribution control make the casting technique more challenging for the manufacturing of closed deck cylinder blocks.
Technical Paper

Automotive Evaporator Performances Under Different Humidity Conditions

2004-03-08
2004-01-1381
Environment and A/C loop conditions strongly affect automotive evaporator performance. The aim of the activity is to identify the parameters it depends on and its functional dependence. Several evaporators, differing in size and technology, are tested on a bench, simulating a wide range of working conditions. The evaporator efficiency is introduced in order to correctly evaluate performances. The functional dependences from air velocity and humidity (key parameters) are shown, and a methodology to characterise automotive evaporators is proposed.
Technical Paper

Stationary Model to Predict Performance of the Car Air Conditioning System Using Only Standard Components Data

2001-03-05
2001-01-0589
A stationary model of a car air conditioning system was developed to evaluate refrigerant, mechanical power and all the fluid properties along the circuit. The model requires only the characteristics of the constituents, which are normally available from suppliers. This approach enables estimation of system performance with satisfactory accuracy, already during the design approach, and allows to determine the most appropriate components in order to meet target requirements with a satisfactory balance of the refrigerant circuit.
Technical Paper

Evaluation Criteria for AWD Vehicles System Analysis

2004-05-04
2004-01-2086
Handling behaviour is a very important aspect of modern cars, which need to reach high levels of lateral acceleration maintaining good stability and driveability. The presence of an AWD powertrain changes the response of the vehicle and then it is very important to qualify the car behavior in terms of perceived performances through objective indexes. The paper presents the development of evaluation criteria for AWD vehicles objective assessment; simulation tools and SW standard procedure has been optimised for AWD performances virtual evaluation and different architectures (locking, self-locking, visco-coupling, active differentials) are compared in terms of longitudinal, lateral and cross-coupling dynamics performances. Through the proposed methods it is possible to make vehicle system analysis using simulation model and standard procedures to classify different AWD architectures.
Technical Paper

Simulation Tools and Evaluation Criteria for Steering Wheel Feel Improvement of an Electric Power Steering System

2002-05-07
2002-01-1593
Centro Ricerche Fiat in collaboration with Fiat Auto vehicle test department has developed a numerical-experimental procedure in order to support on-road development and fine tuning of a new car with electric power steering. The integration of an electric power steering model, given by the supplier, in a full vehicle model, in order to evaluate steering feel objective quality indices, has allowed to improve vehicle performance in term of steering feel and reduce on-road development time.
Technical Paper

Customer Orientation in Advanced Vehicle Design

2002-05-07
2002-01-1576
The attention to the perceived quality, e.g. the quality as it is evaluated by the final customer, is becoming more and more important for the car makers. The paper will describe how such aspects of handling and steering system feel may become manageable by an engineering process, through some fundamental steps: definition of measurable performance for the subjective aspects; identification of the target values for such aspects coherent with product positioning; deployment of such overall values generally fixed at vehicle level into functional requirements for the different subsystems and design specifications (sub targets level quantities). This new approach at car advanced design represents an evolution of the traditional one based on some general criteria and experienced designers; it has the aims of reducing time to market and guaranteeing a “customer oriented handwriting” in handling behaviour and steering feel.
Technical Paper

The Seat Thermal-Hygrometric Performance Measurement and Its Correlation With Perceived Comfort

2001-10-01
2001-01-3432
The air conditioning system is becoming more and more a competitive issue, moving from optional to standard vehicle equipment. Therefore, also thermal comfort level is moving from simple air temperature measurement to a more systemic approach, where the contribution of every element of the car cabin has to be taken in account. Improving contact thermal sensation with the seat is one of the main issues to improve overall thermal comfort in transportation. A method has been defined to assess the perceived thermal quality of seats taking into account the sweating human thermoregulatory process. The method is based on a thermal manikin representing a torso able to simulate in a portion of the back the sweating phenomena. The first part of the paper is focused on the instrument and developed measuring method description. The second part is dedicated to detail the correlation between experimental measurements and subjective quality index obtained during an extensive on-road panel test.
Technical Paper

Soft Air Diffusion to Improve the Thermal Comfort - a Design Approach Based on CFD Tool and Virtual Thermal Manikin

2001-10-01
2001-01-3439
The cabin comfort is one of the most competitive issues in the automotive area of business. The thermal comfort and the environmental well-being are fundamental performances that contribute to generate the more general idea of perceived quality. The CRF developed in the past the concept so-called “healthy bubble” that was implemented in the Lancia Dialogos concept car. The passengers are surrounded by an air bubble, created by generating low velocity air flows, that are diffused through the interior panels and components (e.g. dashboard, roof, back of the seats, etc.), and by surfaces temperature control (e.g. carpet, seats, etc.). At present the original idea has generally been accepted, and different solutions to diffuse air and to control surface temperature of vehicle interiors have been proposed by some automotive supplier.
Technical Paper

The ATENA Project: An integrated solution of advanced vehicle technology and telematics to environmental impact

2001-09-23
2001-24-0084
The Public Administrations all over the world are looking for new methodologies and tools to face traffic congestion and pollution problems in order to obtain an efficient and environmentally sustainable city. Looking at the new technologies, the City Council of Naples promoted an advanced telematic system to manage the urban traffic and a pilot study on a fleet of low emission vehicles using different fuel sources. The pilot project was called ""ATENA"" (Ambiente Traffico Telematica Napoli) and was developed in the City of Naples in a period from 1999 to beginning of 2001. The research project, devised by Fiat Research Center, CSST and other Fiat group companies was financed by the Italian government body MURST (Ministero dell'Università e della Ricerca Scientifica e Tecnologica) as well as the European Community.
Technical Paper

Preliminary results on emissions and driving behavior of ATENA fleet test project in Naples

2001-09-23
2001-24-0083
One of the objectives of the Atena project was the definition of methods for the predictive evaluation of the environmental impact of different types of vehicles used in an urban scenario. The target is to obtain a methodology that allows the decision maker to verify in simulation the effects of possible measures like the law enforcement to the access restrictions or vehicle fleet composition. The main obstacle is the realization and managing of real driving cycles in order to overtake the limits derived from the utilization of typical cycles (i.e., ECE + EUDC) or the simple consideration of average speed. The starting point is a digital representation of the urban network where all the roads are represented with one or more arcs and for all these arcs are available an estimation of the traffic variables like the vehicle flow (vehicles per hour) or the average speed (kph). Every arc is described in terms of traffic parameters like the type of road (i.e., highway, district road).
Technical Paper

Hybrid pollutants emissions and driving experimental results

2001-09-23
2001-24-0036
One of the way for improving environmental performances of car propulsion system is the adoption of hybrid systems where the internal combustion engine (ICE) is coupled or temporary overtaken by an electric motor. The reference prototype of this article is the FIAT Multipla Hybrid where are possible three functional modes: Pure Electric mode, Serial Hybrid and Parallel Hybrid. Particularly it was approached the torque splitting algorithm applied to the parallel hybrid one; the work was first tested in simulation, after implemented in the electronic control units and finally tested on the field using the test bench of the 10 hybrid vehicles that belongs to the Atena Project [1].
Technical Paper

On Board Diagnosis of A/C System Refrigerant Charge Level

2002-03-04
2002-01-0231
The air conditioning system of a car uses the reverse Carnot thermodynamic cycle of a refrigerant gas. The fluids normally used have at least a direct impact on global warming, so their losses have to be avoided. A very simple method to detect refrigerant charge level was developed, using few standard sensors. Results show that it is possible to have an estimation of system charge level with satisfactory accuracy, and seems able to avoid complete loss of refrigerant.
Technical Paper

A Rapid Prototyping Methodology for the Decision Making Algorithms in Automotive Electronic Systems

2002-03-04
2002-01-0754
The importance of the numerical simulation and testing techniques for the software specifications development of on-board automotive systems design is the paper main issue. In order to promote flexible and rapid procedures improving software specifications, new methodologies are necessary. The proposed procedure is based on the design, simulation, validation, software compiling and rapid prototyping algorithms concerning management strategies of automotive electronic systems. The new feature of this methodology is provided by the comparison between two prototyping environment outputs: rapid prototyping tool outputs represented by strategies running in DSpace® using powerful microprocessors and CPU outputs characterized by limited calculation resources of an almost real one.
Technical Paper

Experimental Investigation of Fuel Consumption, Exhaust Emissions and Heat Release of a Small-Displacement Turbocharged CNG Engine

2006-04-03
2006-01-0049
An experimental investigation of fuel consumption, exhaust emissions and heat release was performed on a prototype 1.2 liter 4 cylinder turbocharged CNG engine, which has been specifically developed and optimized in order to fully exploit natural gas potential. More specifically, the combination of a high CR of 10.1:1 and a Garrett high-performance turbocharger featuring selectable levels of boost produced a favorable efficiency map, with peak values exceeding 35%. The experimental tests were carried out in order to assess the engine performance improvement attainable through turbocharging and to define the best control strategies for this latter. The investigation included ample variations of engine speed and load, RAFR as well as trade-offs between boost level and throttle position. At each test point, in-cylinder pressure, fuel consumption and ‘engine-out’ pollutant emissions, including methane unburned hydrocarbons concentration, were measured.
Technical Paper

A Metal Hydride Mobile Air Conditioning System

2006-04-03
2006-01-1235
This paper describes the development of an electrical compressor-driven air conditioning system for automotive applications. The system uses the thermal properties of reversible metal hydride alloys, which are retained within advanced-design hydride heat exchangers. Calculations on system performance predict high energy efficiency in a package of competitive size and cost. A proof-of-principle prototype has been constructed and bench tested. Measurements from initial tests confirm the excellent performance potential of this system. A study about on-board integration concludes that the system can be installed on a car and can provide all HVAC traditional functions.
Technical Paper

Idle Speed Control with H-Infinity Technique

1993-03-01
930770
This paper describes an application of the H-infinity optimal control theory to the design of an engine idle speed electronic regulator. This technique, working directly on multi-input multi-output systems, allows to achieve optimal performances, good disturbances rejection and robustness to parametric variation of the plant. Compared to the current heuristic techniques for the tuning of the control parameters, the following procedure offers the opportunities to become completely automatic, reducing in this way time and efforts. The experimental results, finally, are better than those obtained by conventional P.I.D. regulators and equivalent of an optimal L.Q.I, ones.
Technical Paper

Integrating Fluid-Acoustic Unidimensional Models in the Time and Frequency Domains

1993-05-01
931296
In order to describe simultaneously the thermo-fluid dynamics and the acoustics of an Internal Combustion engine, a mathematical model and a computer program has been developed which integrate the Method of the Characteristics with the Acoustic. Transfer Matrix Method. The former method is currently used to model the fluid dynamics of Internal Combustion engines, whilst the latter allows the description of the acoustical behaviour of the intake and exhaust systems. The theory presented in the article integrates the two approaches, allowing the fluid-acoustics of the global system engine-silencers to be described, taking into account the mutual interactions. Preliminary investigations on a simplified system, constituted of a constant section duct, have demonstrated the consistency and validity of the model.
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