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The traction motor is key to the �synergy of the electric powertrain�, the overall functionality of the battery, e-motor, power control electronics, and charging system. Therefore some automakers have decided to design, develop, and produce their traction motors in house while some others are working with suppliers for their electric power train motors. Off-the-shelf motors, no matter how extensively they are adapted for a specific application, can compromise the efficiencies of the propulsion system. Presenter Marc Winterhoff, Roland Berger Strategy Consultants

Who are the people who know the most about the buses in your fleet? They are most likely the operators and the servicing technicians. They are also the key people whose knowledge, level of training and attitude can determine the success or failure of new powertrain technologies. Training and recruitment of both need to be held to a higher standard than we have seen in the past. I will argue that even the culture of those involved in fleet operations needs to be changed. The bar for technical competence and product knowledge needs to be raised for operators and technicians. In return managers should find ways to include them as stakeholders, investing them with both additional responsibility and accountability. This will require greater access to training and recognition of achievement. Where are the busses stored and serviced? Most likely in an all-purpose state/county/municipal service facility servicing a variety of equipment.

In order to extend the CAI operation range in 4-stroke mode and maximize the benefit of low fuel consumption and emissions in CAI mode, 2-stroke CAI combustion is revived operating in a GDI engine with poppet valves, where the conventional crankcase scavenging is replaced by boosted scavenging. The CAI combustion is achieved through the inherence of the 2-Stroke operation, which is retaining residual gas. A set of flexible hydraulic valve train was installed on the engine to vary the residual gas fraction under the boosting condition. The effects of spark timing, intake pressure and short-circuiting on 2-stroke CAI combustion and its emissions are investigated and discussed in this paper. Results show the engine could be controlled to achieve CAI operation over a wide range of engine speed and load in the 2-stroke mode because of the flexibility of the electro-hydraulic valvetrain system. Presenter Yan Zhang, Brunel University

Abstract The high-frequency noise issue is one of the most significant noise, vibration, and harshness problems, particularly in battery electric vehicles (BEVs). The sound package treatment is one of the most important approaches toward solving this problem. Owing to the limitations imposed by manufacturing error, assembly error, and the operating conditions, there is often a big difference between the actual values and the design values of the sound package components. Therefore, the sound package parameters include greater uncertainties. In this article, an uncertainty analysis method for BEV interior noise was developed based on an interval model to investigate the effect of sound package uncertainty on the interior noise of a BEV. An interval perturbation method was formulated to compute the uncertainty of the BEV’s interior noise.

Abstract To gain a better understanding of the characteristics of corrugation, including the development and propagation of corrugation, and impact of vehicle and track dynamics, a computational model was established, taking into account the nonlinearity of vehicle-track coupling. The model assumes a fixed train speed of 300 km/h and accounts for vertical interaction force components and rail wear effect. Site measurements were used to validate the numerical model. Computational results show that (1) Wheel polygonalisation corresponding to excitation frequency of 545-572 Hz was mainly attributed to track irregularity and uneven stiffness of under-rail supports, which in turn leads to vibration modes of the bogie and axle system in the frequency range of 500-600 Hz, aggregating wheel wear. (2) The peak response frequency of rail of the non-ballasted track coincides with the excitation frequency of wheel-rail coupling; the resonance results in larger wear amplitude of the rail.

Over 30 years ago, A. H. Vincent of Westland Helicopters demonstrated that if a structure is excited harmonically, the response at another position (at a fixed frequency) will trace a circle in the complex plane as a result of a dynamic stiffness modification between two points. As either the real or imaginary part of an introduced dynamic stiffness is varied from minus infinity to plus infinity, the structural or acoustic response on any position will map a circle in the complex plane. This paper reviews the basis for this little known principle for vibro-acoustics problems and illustrates the viability for a cantilevered plate example. The applicability of the method is then considered for strictly acoustic systems like intake and exhaust systems. Specifically, it is shown that the response traces a circle in the complex plane if either the real or imaginary parts of the source or termination impedance are varied from minus to plus infinity.

The acoustic impedance of a circular, confined, side branch orifice subjected to grazing flow is studied. Two geometries are tested. In both geometries, the side branch dimension is of the same order as that of the main duct. The system is viewed as an acoustic three-port, whose passive properties are described by a system matrix. The impedance is studied with the acoustic field incident at different ports, which is shown to influence the results significantly. When excited from the leading edge or from the side branch, an interaction of the hydrodynamic and acoustic fields is triggered, while excitation from the trailing edge does not trigger such an interaction. For both the resistance and the reactance (here expressed as an end correction) the results vary in the three possible excitation cases. In the quasi-stationary limit the resistance is given by a loss coefficient times the Mach number, and the end correction collapses to a single value.

The International Space Station (ISS) United States Operational Segment (USOS) received the first two permanent ISS Crew Quarters (CQ) on Utility Logistics Flight Two (ULF2) in November 2008. As many as four CQs can be installed in the Node 2 element to increase the ISS crew member size to six. The CQs provide crew members with private space that has enhanced acoustic noise mitigation, integrated radiation-reduction material, communication equipment, redundant electrical systems, and redundant caution and warning systems. The rack-sized CQ system has multiple crew member restraints, adjustable lighting, controllable ventilation, and interfaces that allow each crew member to personalize his or her CQ workspace. The deployment and initial operational checkout during integration of the ISS CQ to Node 2 is described in this paper.

This study is based on a project which addresses the reduction of CO2 and pollutant emissions of off-road vehicles. For this purpose the use of CNG drive trains in high alpine areas is an interesting alternative to the standard diesel technology. The same SUV with CNG and diesel powertrain has been measured and methodically compared with regard to fuel consumption and exhaust emission performance. These real-world measurements have shown the potential when applying a CNG concept for this utilization. Subsequently, the real-world on-board measurements were compared with the results of a simulation program for SUV off-road performance.

Research has been conducted on an extended expansion engine, using a multiple linkage system to increase the thermal efficiency of general-purpose engines. In this research, first, the test engine was subjected to an engine acoustics measurement to clarify its noise characteristics. Then, based on the analysis results of the noise characteristics, we propose the direction to reduce the noise of the multiple linkage system engine. When the test engine was operated under a no-load firing condition, rattle noise was observed. Also it was found that the timing of the occurrence of the rattle noise was near after top dead center (ATDC) 90 degrees in crank angle (degCA). Focusing on the gear for linkage drive as a cause of the rattle noise, the authors formulated the torque acting on the gear.

The valve train plays a huge role in the performance of internal combustion engines by controlling the combustion process and is therefore one starting point to increase the efficiency of combustion engines. Considering the dynamics, the valve spring is the component with the lowest natural frequency in the motor and therefore plays a crucial role in the overall dynamics of the valve train. The spring force must be high enough to close the valve reliably and prevent the valves from bouncing of the seating due to surge modes after they have closed. Conversely, the spring force affect the friction level in the engine and therefore fuel consumption. For this reason the spring forces should be kept as low as possible. Modelling valve springs it has to be taken into account, that the dynamic response of the spring is substantially different from the static response.

A turbocharged 2.0L 4-cylinder direct injection spark ignition (DISI) engine designed for use with gasoline is simulated using one dimensional engine simulation. Engine design modifications - increased compression ratio, 2-step valve train with dual independent cam phasing and fuel injection timing - are considered in an effort to improve fuel economy with gasoline and take advantage of properties of ethanol fuel blends (up to E85). This paper discusses a methodology to use the simulation to quantitatively evaluate the design modification effects on fuel economy. Fuel consumption predictions from the simulation for each design are evaluated. The goal is to identify the best design with the constraints of hardware physical limitations, engine residual tolerance and knock tolerance. The result yields a specification for a 2-step valve train design and phasing requirements that can improve fuel economy for each compression ratio design.

A 2.0 l turbocharged gasoline engine with port injection and a comparable turbocharged gasoline engine with direct injection have been investigated on a test bench at Kaiserslautern Technical University. Both engines were driven with throttle-free load control by fully mechanically variable valve actuation (CVVL). The basic series-production turbocharged engine in this comparison is the version with direct injection without the fully variable valve train. The focuses of the fired tests were investigation of the fuel consumption at part load and of maximum torque behavior at low engine speeds at full load. In both engine modes, use of fully variable valve actuation shows improvements compared with the turbocharged engine versions without CVVL. Better turbocharger response enabled the torque behavior to be optimized.

Fully variable valve trains provide comprehensive means of adjustment in terms of variable valve timing and valve lift. The efficiency of the engine is improved in the operating range and in return, an increasing complexness of the mechanical design and control engineering must be handled. For optimization and design of these kinds of complex systems, detailed simulation models covering different physical domains, i.e. mechanics, hydraulics, electrodynamics and control are needed. Topic of this work is the variable valve train named Audi valvelift system (AVS) e.g. used in the Audi 2.8l V6 FSI engine. The idea of AVS is to use different cam lobes at different operating points. Each intake valve can be actuated by a large and a small cam. For full load, the two inlet valves are opened by the large cam profile - ideal for high charge volumes and flow speeds in the combustion chamber. Under partial load, the small cam profiles are used.

In recent years, computer simulations gained an increased role in the design, development, optimization, and calibration of the valve train systems. With the development of non-conventional systems and actuation mechanisms, computer modeling became even more important. Part I of this article presents an overview of the current modeling and simulation methods of conventional valve trains at component and system level. First, the modeling of the valve train kinematics, including cam shape design and optimization, is summarized. Mathematical modeling of the valve spring, hydraulic lash adjuster, oil aeration, bulk modulus, contact stiffness and contact damping in multibody systems are discussed. The benefits and limitations of the different modeling approaches of the valve train dynamics are pointed out. Another important aspect is the valve train tribology.

Intensive R&D is currently performed worldwide on hybrid and electric vehicles. For full electric vehicles the driving range is limited by the capacity of currently available batteries. If such a vehicle shall increase its driving range some range extending backup system should be available. Such a Range Extender is a small system of combustion engine and electric generator which produces the required electricity for charging the batteries in time. Since the acoustic response of an electric motor driving the vehicle and of a combustion engine as part of a Range Extender is very different by nature an extensive acoustic tuning of the Range Extender is necessary to meet the requirements of exterior vehicle noise and passenger comfort. This paper describes the NVH (noise, vibration & harshness) development work of a range extender within the AVL approach of an electrically driven passenger car with range extender.

The target of the investigation is the particular influence of a fuel injection system and its components as a noise source in automotive engines. The applied methodology is demonstrated on an automotive Inline 4-cylinder Diesel engine using a common rail system. This methodology is targeted as an extension of a typical standard acoustic simulation approach for combustion engines. Such approaches basically use multi-body dynamic simulation with interacting FEM based flexible structures, where the main excitation crank train, timing drive, valve train system and piston secondary motion are considered. Within the extended approach the noise excitation of the hydraulic and mechanical parts of the entire fuel system is calculated and subsequently considered within the multi-body dynamic simulation for acoustic evaluation of structural vibrations.

Inverse numerical acoustics is a method which reconstructs the source surface normal velocity from the sound measured in the near-field around the source. This is of particular interest when the source is rotating or moving, too light or too hot to be instrumented by accelerometers. The use of laser vibrometers is often of no remedy due to the complex shape of the source. The Inverse Numerical Acoustics technique is based on the inversion of transfer relations (Acoustic Transfer Vectors) using truncated Singular Value Decomposition (SVD). Most of the time the system is underdetermined which results in a non unique solution. The solution obtained by the truncated SVD is the minimal solution in the RMS sense. This paper is investigating the impact of non homogeneities in the mesh density (local mesh refinement) on the retrieved solution for underdetermined systems. It will be shown that if transfer quantities are inverted as such, big elements get a higher weight in the inversion.

Airflow resistivity is one of the most important parameters in the study of the physical properties of porous acoustic materials. This parameter is fundamental for the correct evaluation of sound absorption of acoustic materials and is needed in all the theoretical models. In the present work, airflow resistivity of porous materials is determined under effective operating conditions inside a vehicle (temperature, compression of the panels). Starting from the discussion on the measurement uncertainty, experimental data of airflow resistivity, measured as a function of temperature and applied static loads, are presented. By introducing the measured values in a SEA model of a typical vehicle panel, the foreseen values of acoustic absorption due to variation of temperature and static load are determined and presented.

Engine efficiency is one of the key aspects to reduce CO₂ emissions. Lamborghini S.p.A. has focused attention on the engine friction modeling, analysis and measurement to understand and control the phenomena. To reduce friction it is necessary to improve understanding of the behavior of the engine components and to pay attention to detail at every tribological contact. The valve train can make a significant contribution to whole engine friction especially at low engine speed and this is particularly true for a high speed sports car engine. Direct acting valve trains are often used for this type of engine to minimize the moved mass and so enable high speed operation. However the sliding contact between the cam and tappet results in higher friction loss than the roller finger follower valve train used on many modern passenger car engines. In addition, the high maximum engine speed demands a large valve spring force to maintain contact between cam and tappet.