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In the last years, the engineering in the automotive industry is revolutionized by the continuous research of solutions for the reduction of consumptions and pollutant emissions. On this topic maximum attention is paid by both the legislative bodies and the costumers. The more and more severe limitations in pollutant and CO2 emissions imposed by international standards and the increasing price of the fuel force the automotive research to more efficient and ecological engines. Commonly the standard approach for the definition of the engine parameters at the beginning of the design process is based on the wide-open throttle condition although, both in homologation cycles and in the daily usage of the scooters, the engines work mainly at partial load where the efficiency dramatically decreases. This aspect has recently become strongly relevant also for two wheeled vehicles especially for urban purpose.

The paper describes the components of an envisioned open source framework that supports several stages in the model-based development of two- and three-wheelers software controls. The proposed solution supports the runtime execution on an OSEK-compatible [8] real-time operating system for multicore platforms. The framework consists of a modeling and simulation tool (including hierarchical state machines) and a code generator for the development of the functional model of controls and the definition of their task implementation; an OSEK/AUTOSAR operating system and device driver stack; OS and I/O configuration tools. The platform has been released open-source under an industry-friendly license. Our framework is currently in use for the development of innovative two-three wheelers control systems at Piaggio. In this paper we describe the experience matured in the application development, the benefits and current limitations of the approach.

The small engine for two-wheel vehicles has generally high possibility to be optimized at low speeds and high loads. In these conditions fuel consumption and pollutants emission should be reduced maintaining the performance levels. This optimization can be realized only improving the basic knowledge of the thermo-fluid dynamic phenomena occurring during the combustion process. It is known that, during the fuel injection phase in PFI SI engines, thin films of liquid fuel can form on the valves surface and on the cylinder walls. Successively the fuel films interact with the intake manifold and the combustion chamber gas flow. During the normal combustion process, it is possible to achieve gas temperature and mixture strength conditions that lead to fuel film ignition. This phenomenon can create diffusion-controlled flames that can persist well after the normal combustion event. These flames induce the emission of soot and unburned hydrocarbons.

The match between the increasing performance demands and stringent requirements of emissions and fuel consumption reduction needs a strong evolution in the 2-wheel vehicle technology. In particular many steps forward should be taken for the optimization of modern small motorcycle and scooter at low engine speeds and low temperature start. To this aim, the detailed understandings of thermal and fluid-dynamic phenomena that occur in the combustion chamber are fundamental. In this work, experimental activities were realized in the combustion chamber of a single-cylinder 4-stroke optical engine. The engine was equipped with a four-valve head of a commercial scooter engine. High spatial resolution imaging was used to follow the flame kernel growth and flame front propagation. Moreover, the effects of an abnormal combustion due to firing of fuel deposition near the intake valves and on the piston surface were investigated.

The purpose of the study is to develop a flexible simulation tool that allows coupling the 1-D simulation of the engine with the dynamic simulation of the whole vehicle on which the engine is installed, in order to predict vehicle operating conditions and exhaust emissions during an imposed mission profile. In fact 1-D engine simulation can supply information on engine performance but not on vehicle performance, that strongly depends on the vehicle itself. Therefore vehicle performance simulation needs an integrated engine-vehicle approach. The dynamic model of the vehicle (a scooter with CVT transmission) is built up in Matlab-Simulink while the engine model is realized by means of a 1-D commercial code (WAVE, Ricardo Software). In particular, the Urban Driving Cycle (UDC) of the European Community ECE-40 homologation test (established by the EL) directive 2002/51/CE) for a scooter with CVT transmission and centrifugal clutch is the aim of the simulation activity.

This paper describes the development of a control-oriented model that allows the simulation of the Internal Combustion Engine (ICE) thermodynamics, including pressure wave effects. One of the objectives of this work is to study the effects of a Variable Valve Timing (VVT) system on the behavior of a single-cylinder, four-stroke engine installed on a motor scooter. For a single cylinder engine running at relatively high engine speeds, the amount of air trapped into the cylinder strongly depends on intake pressure wave effects: it is essential, therefore, the development of a model that has the ability to resolve the wave-action phenomena, if successful simulation of the VVT system effects is to be performed.

The match among the increasing performance demands and the stringent requirements of emissions and the fuel consumption reduction needs a strong evolution in the two-wheel vehicle technology. In particular, many steps forward should be taken for the optimization of modern small motorcycles and scooters at low engine speeds and high loads. To this aim, detailed understanding of thermo-fluid dynamic phenomena that occur in the combustion chamber is fundamental. In this work, low-cost solutions are proposed to optimize ported fuel injection spark ignition (PFI SI) engines for two-wheel vehicles. The solutions are based on the change of phasing and on the splitting of the fuel injection in the intake manifold. The experimental activities were carried out in the combustion chamber of a single-cylinder 4-stroke optical engine fuelled with European commercial gasoline. The engine was equipped with a four-valve head of a commercial scooter engine.

In this paper the feasibility of the application of a system conceived by Järvi to a 125 cm3, four strokes motorcycle engine built by Piaggio Company is investigated. This study was carried out using a one-dimensional model built with the well known CFD 1D code Wave and validated in a previous work. An analytical study was performed on the kinematic scheme of the mechanism in order to establish the relationship between control ramp and valve lift. The control ramp shape was then optimized accordingly with the results of the fluid dynamic analysis performed through the above mentioned Wave model.

The efficiency of engine operations, i.e. cold start, transient response and operating at idle, depends on the capability of the injection fuel system to promote a homogeneous mixture formation through an efficient interaction with engine fluid dynamics and geometry. The paper presents the development and the application of a methodology for running a CFD PFI engine simulation. A preliminary assessment of the wall-film and droplet-wall interaction sub models has been carried out in order to validate the methodology. Then a three-step numerical procedure has been adopted. The first two steps are aimed to properly initialize the secondary breakup model depending on the type of injector installed on board in order to achieve accurate predictions of spray characteristics.

A very stringent problem in most of European cities is the individual mobility. This problem is mainly caused by traffic jam and arising from this are two particularly interesting environmental issues: pollution and noise [1]. Use of two wheeler vehicles does not represent the final solution to these problems, nevertheless they can supply a useful aid to ease them. Recently, two stroke engines are being replaced with four stroke engines. For small capacity engines this means a true reduction in exhaust emissions, especially unburned hydrocarbons (HC), but, on the other hand it involves a performance reduction, particularly for sudden accelerations, which constitute an essential requirement for these vehicles [2, 3, 4, 5]. Hybridisation can help to fill the gap between two stroke engines and cleaner, but less performing four stroke engines [6]. At the same time, it can help to lower fuel consumption, by means of a reduction in the revolution speed [2, 5].

Exhaust emissions have been achieving a huge importance in the last years due to the introduction of more and more restricted environmental and legislation laws on pollutant emissions. The scavenging process of a two stroke engine has been analysed using the Computational Fluid Dynamics (CFD) technique in order to determine the emission of fresh charge in the conditions specified by ECE47 cycle. Different geometries of inlet ports and of combustion chambers have been simulated to obtain a good loop scavenged flow and a consequent reduction of hydrocarbon emissions.

The paper presents an innovative drive-train for a small scooter, taking advantage of an hybrid (mechanical-electrical) structure. The single parts of this drive train have been dimensioned and the resulting system has been introduced in a simulation program. According to the simulation results the hybridisation is able to enhance the maximum power of the scooter by 1 kW (over 30%), without changing the fuel consumption, and to allow a pure-electric operation with a range over 11 km. Moreover, when the propulsion power comes only from the onboard batteries, and they are recharged from the electric mains, the operation cost per km is less than one half the cost of corresponding fuel consumption of a vehicle without hybridisation.

In this work a lumped-parameter model, able to simulate the dynamic behavior of different types of valve train systems, was developed. Among the various aspects, the rocker arm flexibility, the valve lash, the possibility that the mechanical elements lose contact with each other and the possible impact of the valve in its seat were taken into account. The model includes two different descriptions of the valve spring, which can be schematized either by an ideal elastic reaction or by a multi-mass scheme, including the possibility of contact among adjacent masses.