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Beside the automotive industry, where 2-cylinder inline engines are catching attention again, twin-cylinder configurations are quite usual in the small engine world. From stationary engines and range-extender use to small motorcycles up to big cruisers and K-Cars this engine architecture is used in many types of applications. Because of very good overall packaging, performance characteristics and not least the possibility of parts-commonality with 4-cylinder engines nearly every motorcycle manufacturer provides an inline twin in its model range. Especially for motorcycle applications where generally the engine is a rigid member of the frame and vibrations can be transferred directly to the rider an appropriate balancing system is required.

Beside hard facts as performance, emissions and fuel consumption especially the brand specific attributes such as styling and sound are very emotional, unique selling prepositions. To develop these emotional characters, within the given boundary conditions of the future pass-by regulation, it is necessary to define them at the very beginning of the project and to follow a consequent development process. The following paper shows examples of motorcycle NVH development work on noise cleaning and sound engineering using a hybrid development process combining front loading, simulation and testing. One of the discussed solutions is the investigation of a piston pin offset in combination with a crankshaft offset for the reduction of friction. The optimization of piston slap noise as a result of the piston secondary motion was performed by simulation. As another example a simulation based development was performed for the exhaust system layout.

For noise quality and brand sound design of passenger cars a unique software tool is currently used by our clients world-wide to evaluate and optimise the interior noise quality and brand sound aspects of passenger cars on an objective basis. The software tools AVL-VOICE and AVL-COMFORT are designed for the objective analysis of interior noise quality, for benchmarking, for the definition of noise quality targets and most important for effective vehicle sound engineering. With this tool, the target orientated implementation of the required interior noise quality or brand sound by predictable hardware modifications into passenger cars - for tailor made joy of driving - becomes feasible. The use of this tools is drastically reducing vehicle evaluation time and sound engineering effort when compared with traditional jury subjective evaluation methods and standard acoustic NVH optimisation procedures.

To achieve future fleet CO2 emission targets, all powertrain types, including those with internal combustion engines, need to achieve higher efficiency. Next to others the reduction of friction is one contributor to increase powertrain efficiency. The piston bore interface (PBI) accounts for up to 50 % of the total engine friction losses [1]. Optimizations in this area combined with the use of low viscosity oil, which can reduce the friction of further engine sub-systems, will therefore have a high positive impact. To assess the friction of the PBI whilst considering cross effects of other relevant parameters for mechanical function (e.g. blow-by & wear) and emissions (e.g. oil consumption) AVL has established a holistic development method based around the AVL FRISC (FRIction Single Cylinder) engine with a floating liner measurement concept.

The effective identification and control of powertrain structure borne harmonic noise is one key for achieving the desired noise pattern in a vehicle. Much work is being done in this field to refine and develop transfer path analysis techniques suitable for application at each stage of a vehicle development program. For vehicle application, transfer path analysis and source identification techniques are in use today with varying degrees of success and application complexity. Investigation tools which are fast, do not require extensive vehicle dismantling and yet provide reliable answers, are of great value to NVH and sound quality engineers. A novel Active Path Tracking (APT) method has been developed which is fast to apply and offers immediate practical confirmation of the contributions of all identified chassis transmission paths to the vehicle interior.

DiMethyl Ether (DME) has been known to be an outstanding fuel for combustion in diesel cycle engines for nearly twenty years. DME has a vapour pressure of approximately 0.5MPa at ambient temperature (293K), thus it requires pressurized fuel systems to keep it in liquid state which are similar to those for Liquefied Petroleum Gas (mixtures of propane and butane). The high vapour pressure of DME permits the possibility to optimize the fuel injection characteristic of direct injection diesel engines in order to achieve a fast evaporation and mixing with the charged gas in the combustion chamber, even at moderate fuel injection pressures. To understand the interrelation between the fuel flow inside the nozzle spray holes tests were carried out using 2D optically accessed nozzles coupled with modelling approaches for the fuel flow, cavitation, evaporation and the gas dynamics of 2-phase (liquid and gas) flows.

For nearly twenty years, DiMethyl Ether has been known to be an outstanding fuel for combustion in diesel cycle engines. Not only does it have a high Cetane number, it burns absolutely soot free and produces lower NOx exhaust emissions than the equivalent diesel. However, the physical properties of DME such as its low viscosity, lubricity and bulk modulus have negative effects for the fuel injection system, which have both limited the achievable injection pressures to about 500 bar and DME's introduction into the market. To overcome some of these effects, a common rail fuel injection system was adapted to operate with DME and produce injection pressures of up to 1000 bar. To understand the effect of the high injection pressure, tests were carried out using 2D optically accessed nozzles. This allowed the impact of the high vapour pressure of DME on the onset of cavitation in the nozzle hole to be assessed and improve the flow characteristics.

The target of dynamic simulation is to investigate complex engine dynamic behavior in the whole speed range under different loading conditions in the most effective way during Engine Development Process (EDP). AVL has developed a method for transient run-up analysis by using the simulation tool AVL EXCITE. The main objective of this new method is the controlled speed increase by defining a speed ramp. Transient run-up analysis is of interest for different kind of analysis during the EDP, such as crankshaft dynamics and strength, low frequency vibration analysis, bracket strength and durability analysis, acoustic analysis, etc. By using this method the time required for simulations and thus the whole project duration is significantly reduced. Conventionally the speed range is divided in single speed steps and for each speed a separate transient simulation has to be performed. The number of these simulations depends on the required speed resolution.

In the automotive industry, various simulation-based analysis methods have been suggested and applied to reduce the time and cost required to develop the engine structure to improve the NVH performance of powertrain. This simulation is helpful to set the engine design concept in the initial phase of the powertrain development schedules. However, when using the conventional simulation method with a uniformed force, the simulation results sometimes show different results than the test results. Therefore, in this paper, we propose a method for predicting the radiated noise level of a diesel engine using actual combustion excitation force. Based on the analytical radiated noise development target, we identify the major components of the engine that are beyond this development target by in the frequency range. The components of the problem found in this way are reflected in the engine design of the early development stage to shorten the development time.

The internal combustion engine contains several actuators to control engine performance and emissions. These are controlled within the engine ECU and follow a specific operating strategy to achieve objectives such as NOx reduction and fuel economy. However, these two goals are conflicting and a compromise is required. The operating state depends on system constraints such as engine speed, load, temperature levels, and aftertreatment system efficiency. This results in constantly changing target values to stay within the defined limits, especially the legal emission limits. The conventional approach is to use multiple operating modes. Each mode represents a specific compromise and is activated accordingly. Multiple modes are required to meet emissions regulations under all required conditions, which increases the calibration effort. This new control approach uses an artificial neural network to replace the conventional multiple mode approach.

For a broad acceptance of electric vehicles, the trade-off between all electric range and battery cost respectively weight represents the most important challenge. The all electric range obtained under real world conditions most often deviates significantly from the nominal value which is measured under idealized conditions. Under extreme conditions - slow traffic and demanding requirements for cabin heating or cooling - the electrical range might become less a question of spatial distance but even more of total operation time. Whereas with conventional powertrain, high flexibility of the total driving range can be obtained without sacrificing cost, with a pure battery vehicle this results in extreme high cost and weight of the energy storage. Therefore the difference between the typical daily driving range (e.g. in Germany 80-90% is below 50 km) and the minimum total range requested by most customers for acceptance of battery vehicles (200- 250 km), becomes essential.

Today's powertrains are becoming more and more complex due to the increasing number of gear box types requiring gearshift patterns like conventional (equipped with GSI) and automatic-manual transmissions (AT, AMT), double clutch and continuous variable transmissions (DCT, CVT). This increasing variety of gear boxes requires a higher effort for the overall optimization of the powertrain. At the same time, it is necessary to assess the impact of different powertrains and control strategies on CO₂ emissions very early in the development process. The optimization of Gear Shift Patterns (G.S.P.) has to fulfill multiple constraints in terms of objective customers' requirements, like driveability, NVH, performance, emissions and fuel consumption. For these reasons, RENAULT and AVL entered an engineering collaboration in order to develop a dedicated simulation tool: CRUISE GSP.

In recent years, more attentions have been paid to stringent legislations on fuel consumption and emissions. Turbocharged downsized gasoline direct injection (DI) engines are playing an increasing important role in OEM’s powertrain strategies and engine product portfolio. Dongfeng Motor (DFM) has developed a new 1.0 liter 3-cylinder Turbocharged gasoline DI (TGDI) engine (hereinafter referred to as C10TD) to meet the requirements of China 4th stage fuel consumption regulations and the China 6 emission standards. In this paper, the concept of the C10TD engine is explained to meet the powerful performance (torque 190Nm/1500-4500rpm and power 95kW/5500rpm), excellent part-load BSFC and NVH targets to ensure the drivers could enjoy the powerful output in quiet and comfortable environment without concerns about the fuel cost and pollution.

For vibration and acoustics vehicle development, one of the main challenges is the identification and the analysis of the noise sources, which is required in order to increase the driving comfort and to meet the stringent legislative requirements for the vehicle noise emission. Transfer Path Analysis (TPA) is a fairly well established technique for estimating and ranking individual low-frequency noise or vibration contributions via the different transmission paths. This technique is commonly applied on test measurements, based on prototypes, at the end of the design process. In order to apply such methodology already within the design process, a contribution analysis method based on dynamic substructuring of a multibody system is proposed with the aim of improving the quality of the design process for vehicle NVH assessment and to shorten development time and cost.

With the increasing stringent emissions legislation on ICEs, alongside requirements for enhanced fuel efficiency as key driving factors for many OEMs, there are many research activities supported by the automotive industry that focus on the development of hybrid and pure EVs. This change in direction from engine downsizing to the use of electric motors presents many new challenges concerning NVH performance, durability and component life. This paper presents the development of experimental methodology into the measurement of NVH characteristics in these new powertrains, thus characterizing the structure borne noise transmissibility through the shaft and the bearing to the housing. A feasibility study and design of a new system level test rig have been conducted to allow for sinusoidal radial loading of the shaft, which is synchronized with the shaft’s rotary frequency under high-speed transient conditions in order to evaluate the phenomena in the system.

Fuel consumption is the most important contributor to the total cost of ownership for mass produced motorcycles. Therefore, best fuel economy is one main influencing criteria for a decision to purchase motorcycles. Furthermore, increasingly stringent emission legislations limit and additional OBD requirements must be fulfilled. A new combined test approach has been developed that minimizes accuracy losses in the development process which compensates for the variability of driving behavior in the chassis dyno environment. An engine testbed combined with a belt drive transmission enables operation in single engine or in Powerpack (i.e. internal combustion engine including transmission) configuration as well as under steady state or dynamic operating mode. Since the belt drive transmission is integrated in the test rig, realistic inertia situation for the single engine operating test configuration is ensured.

Cost- and time-efficient vehicle development is increasingly depending on the usage of adequate software tools to enhance effectiveness. The aim is a continuous integration of simulation tools and test environments within the vehicle development process in order to save time and costs. This paper introduces a procedure to reveal the cause of low-frequency powertrain vibrations and the influences on the dynamic behavior of a vehicle on a roller test bench. The affected longitudinal acceleration signal is an arbitrative criterion for the driveability assessment with AVL-DRIVE™, a well-known driveability analysis and development tool for the objective assessment concerning NVH and driveability aspects of full vehicles. These experimental studies are embedded into an approach, which describes the functional assembly of three applied test environments "road," "roller test bench" and "simulation" with according tools in order to facilitate an integrated driveability development process.

The next generation of automotive engines has to meet 2004 emission limits, ideally with improved fuel economy and with noise emission which is at least 3 dBA below the current status. Using both simulation and experimental analysis these challenging requirements can only be fulfilled by clearly defining all key steps in NVH development and by applying suitable technological methods. The development procedure discussed in this paper is characterised by several aspects: two stage prediction procedure fully integrated in the design process, combustion development with a definite focus on noise, a closed loop between simulation and test bed development and consideration of noise in the calibration of engine and drivetrain management systems. Apart from meeting target noise levels, noise quality is the reference parameter which is continuously evaluated by means of the AVL Annoyance Index.

This paper describes a numerical study of the effect of hollow crankshafts on crankshaft local strength and durability as well as slider bearing contact behavior. Crankshaft dynamic simulation for durability is still a challenging task, although numerical methods are already worldwide established and integrated part of nearly every standard engine development process. Such standard methods are based on flexible multi-body dynamic simulation, combined with Finite Element analysis and multi-axial fatigue evaluation. They use different levels of simplification and consider the most influencing phenomena relevant for durability. Lightweight design and downsizing require more and more detailed methods due to higher deformation of the crankshaft. This is especially true for hollow shafts, as present in motorsport design or aerospace applications, but also for standard engine having high potential for significant weight savings.

In the ongoing competition of powertrain concepts the Internal Combustion Engine (ICE) will also have to demonstrate its potential for increased efficiency [1]. Variable Compression Ratio (VCR) Systems for Internal Combustion Engines (ICE) can make an important contribution to meeting stringent global fuel economy and CO2 standards. Using such technology a CO2 reduction of between 5% and 9% in the World Harmonized Light-Duty Vehicle Test Cycle (WLTC) are achievable, depending on vehicle class, load profile and power rating [2]. This paper provides a detailed description of the measurement approaches that are used during development of the AVL Dual Mode VCSTM and other VCR systems in fired operation. Results obtained from these measurements are typically used to calibrate or verify simulation models, which themselves are an integral part of the development of these systems [3].