Browse Topic: Timing belts

Items (156)
Optimum Positioning of FIP Drive System for Type-II BSVI Engine Based on Coupled 1D “Valve-Train - Chain Drive Dynamic Analysis2020-01-10204/14/2020
The automotive industry is gearing up to meet the accelerated emission compliance changes posed by the government. This transition to eco-friendly system would also necessitate an automotive engineer to retain the engine packaging as compact and simple as possible. The packaging layout considered should not be at the expense of deteriorating engine performance. The work started with concept level layout development, with the aim of having simplified system with minimum number of components. The engine on which the work was carried out was 4cylinder 3Liter with OHC configuration A number of layouts were developed which included gear type, belt drive and integrated shaft arrangement for driving FIP. Each of these concepts were brainstormed with its advantages and disadvantages, based on which two concepts were initially proposed for driving FIP system (i) Front Driven FIP (ii) Rear Driven FIP. The difference between the two layouts was that in the latter case the FIP system was directly driven through exhaust camshaft with gear type arrangement. For the above two proposed layouts, dynamic evaluation was done up-to max intermittent speed of engine by modeling complete valve-train system along with chain drive in AVL Excite timing drive. The Excite timing drive model dynamic results showed that with the rear layout FIP system, the valve-train along with chain drive system was getting heavily loaded demanding more robust design leading to an unintentional increase in system mass. For further visualization of the two layouts, engine level testing was done by developing proto parts for both the concepts and the conclusive results were found to be in-line with the simulation results.
Kaundabalaraman, KaarthicRathi, HemantkumarBisht, Jasvir Singh
Study of Adjustable Discontinuous Pulse Width Modulation (ADPWM) Based on Switching Transient Inverter Loss Algorithm2019-01-06024/2/2019
In order to improve the electric vehicle endurance mileage and output characteristics of motor, the optimization of inverter loss and motor current ripple reduction are considered. Aiming at high inverter loss of traditional SVPWM and high current ripple of DPWM, an adjustable discontinuous pulse width modulation(ADPWM) is proposed, whose clamping angle α and clamping phase angle θ are variable. In order to accurately calculate the inverter loss, a switching instantaneous inverter loss model is proposed, and the ADPWM inverter loss and current total harmonic distortion(THD) was studied based on Simulink modeling and simulation. The simulation and experiment results show that the experiment can be accurately reflected by Simulink model; The inverter loss can be reduced by 15%-25% by introducing ADPWM while the current distortion rate is low. With the clamping angle α increasing, the inverter loss decreased significantly. The inverter loss and motor output characteristics are effectively balanced, with setting α ranging from 40° to 55° in high speed and low load condition or setting α =55° in high speed full load condition. When α is a constant, the motor current characteristics are improved and inverter loss is reduced by the appropriate advanced clamping phase angle(-15°<θ<-5°). The continuous variable seamless conversion between different PWM methods can be realized by ADPWM.
Xu, XiaoChuanWang, JinZheng, DongkaiZhang, Jian
Noise Problem Resolution and Sound Quality Improvement of Valve Timing Belt in 4 Cylinders PFI Gasoline Engine2019-01-07834/2/2019
IC Engine Timing belt is a major noise prone area and it takes time during development to achieve acceptable NVH characteristics. In an existing engine under series production noise problem observed due to excitation of timing belt span by crank timing sprocket tooth. From vehicle perspective noise was heard in vehicle cabin at around idling RPM and a second peak observed around twice the initial RPM. This paper includes a methodology for use of computer based analytical simulation methods to predict timing belt dynamic behavior and NVH characteristics. Along with development of computer based multi body dynamic model for timing belt, validation of simulation model with actual testing was done and after correlation of testing and simulated results countermeasure were finalized based on iterations in multi body simulation model. Multi body dynamics model of timing drive indicated resonance in one belt span when belt transverse vibration amplitude was converted from time domain to frequency domain using FFT. In an existing engine layout change to modify belt span length was not feasible to avoid resonance, other alternatives like reduction of belt natural frequency (by increasing belt mass density, tension reduction etc.) were explored using parametric simulation model. Final solution to avoid belt resonance in engine working RPM range was proposed as reduction of belt natural frequency by modifying the belt tension. Above proposal was checked on engine bench and anechoic vehicle test showed noise reduction of 5 and 11 dB at first and second harmonic respectively due to avoidance of resonance in engine working RPM range. Multi body dynamic simulation model helped to drastically reducing the number of testing trials/combination used to resolve the NVH issue of timing belt.
Poonia, SanjaySingh, AmandeepSingh, JaspreetSharma, ShailenderKumar, Narinder
An Innovative Electric Motor Cooling System for Hybrid Vehicles - Model and Test2019-01-10764/2/2019
Enhanced electric motor performance in transportation vehicles can improve system reliability and durability over rigorous operating cycles. The design of innovative heat rejection strategies in electric motors can minimize cooling power consumption and associated noise generation while offering configuration flexibility. This study investigates an innovative electric motor cooling strategy through bench top thermal testing on an emulated electric motor. The system design includes passive (e.g., heat pipes) cooling as the primary heat rejection pathway with supplemental conventional cooling using a variable speed coolant pump and radiator fan(s). The integrated thermal structure, “cradle”, transfers heat from the motor shell towards an end plate for heat dissipation to the ambient surroundings or transmission to an external thermal bus to remote heat exchanger. A complete lumped parameter numerical modelling was implemented to estimate the thermal behavior of the corresponding electric motor cooling system. Experimental and numerical results compare the temperature, heat flux, and cooling power measurements. For 250VA thermal load applied, the hybrid heat rejection strategy could save up to 33% of the power consumption while the operating condition is secured. Higher thermal loads can be handled through the combined passive and active pathways with minimum power consumption. Based on these findings, integrated electric motor cooling merits attention for further investigation through field testing, scaling, and utilization in other applications.
Shoai Naini, ShervinHuang, Junkui (Allen)Miller, RichardWagner, John R.Rizzo, DeniseSebeck, KatherineShurin, Scott
Development, Performance Analysis and Optimization of Parallel Hydraulic Hybrid System for City Bus Application2018-01-04194/3/2018
One of the key requisites for a sustained mobility development is to have an efficient public transport system. Fuel efficiency and emission control are extremely important in this respect. By the very nature of city driving, it is obvious that city traffic results in frequent vehicle start and stops; which involves huge waste of vehicle kinetic energy. Every time vehicle moving from idle, needs a bigger input of power and every time the brakes are applied, all energy built up disappears again, wasted in the brake pads as heat. An effort has been taken to recuperate vehicle kinetic energy, hydraulically during braking events and utilize it to assist the vehicle during acceleration. Hydraulic based hybrid vehicle working on the principle of regenerative braking is one of the most fuel-efficient technologies for city application. Parallel hydraulic hybrid vehicle has been developed and optimized for fuel efficiency gain at vehicle level. Objective of this paper is to study behavior, performance and optimization of hydraulic hybrid vehicle in city application. This paper deals with evaluation of simulation, integration, calibration and performance tests carried out at real world usage conditions. As a final proof of concept and performance, the hydraulic hybrid bus was tested back to back with conventional city bus of same configuration and results were analyzed and compared. This paper also deals on the scope of engine downsizing and major challenges faced in developing hydraulic hybrid system for extremely hot weather conditions such as South Asian countries.
Yaser, K U Syed TajBakatwar, RupeshBhargava, AashishTiwari, Sanjay
New 1.0L I3 Turbocharged Gasoline Direct Injection Engine2017-01-10293/28/2017
To comply with the environmental demands for CO2 reduction without compromising driving performance, a new 1.0 liter I3 turbocharged gasoline direct injection engine has been developed. This engine is the smallest product in the new Honda VTEC TURBO engine series (1), and it is intended to be used in small to medium-sized passenger car category vehicles, enhancing both fuel economy through downsizing, state-of-the-art friction reduction technologies such as electrically controlled variable displacement oil pump and timing belt in oil system, and also driving performance through turbocharging with an electrically controlled waste gate. This developed engine has many features in common with other VTEC TURBO engines such as the 1.5 liter I4 turbocharged engine (2) (3), which has been introduced already into the market. Some of these are the rapid combustion concept realized by high tumble intake port design and the optimized combustion chamber configuration combined with a side mounted multi-hole direct injection system. In addition to VTC (valve timing control system), the VTEC (Variable valve timing and lift electronic control system) has been used in the intake valve system in order to realize an Atkinson cycle to reduce fuel consumption in low valve lift mode. Investigation results show that side-mounted direct injection has potential comparable to that of central-mounted direct injection in terms of mixture homogeneity and combustion chamber wall wetting, while no disadvantage in combustion performance was observed. Through such technologies, this developed engine achieved top level of fuel consumption characteristics in this class, contributing to improve the fuel economy by 26% from the previous engine in NEDC (new European driving cycle) mode.
Shibata, Mitsuhirokawamata, MasashiKomatsu, HirotakaMaeyama, KazukiAsari, MasaruHotta, NaokiNakada, KazutakaDaicho, Hisashi
Matching Design and Parameter Sensitivity Analysis of Micro Electric Vehicle Drive-motor’s Power2017-01-15943/28/2017
Micro electric vehicle has gained increasingly popularity among the public due to its compact size and reasonable price in China in recent years. Since design factors that influence the power of electric vehicle drive-motor like maximum speed, acceleration time and so on are not fixed but varies in certain scopes. Therefore, to optimize the process of matching drive-motor’s power, qualitatively and quantitatively studies should be done to determine the optimal parameter combination and improve the design efficiency. In this paper, three basic operating conditions including driving at top speed, ascending and acceleration are considered in the matching process. And the Sobol’ method of global sensitivity analysis (GSA) is applied to evaluate the importance of design factors to the drive-motor’s power in each working mode. Then the most influential factors in determining the peak power are identified with Sobol’ method and an improved algorithm proposed in the paper by regarding the design process as a black-box model since the power of drive-motor must meet the three performance requirements of micro electric vehicle after all. Finally, local sensitivity analysis (LSA) based on the perturbation method is adopted to evaluate the impact of parameters variation on the power of drive-motor in a small range. In conclusion, the sensitivity analysis results reveal that acceleration time, vehicle’s maximum speed and the speed ratio of the drive-motor are the most crucial factors in the matching process while the others can be neglected under given conditions thus providing a reference to the enhancement of micro electric vehicle’s design efficiency.
Zhuo, GuirongXiong, KunZhang, Subin
An often asked question from industrial machine builders or integrators is how they can effectively design or implement the conversion of a machine with servo technology to meet performance expectations. This is a specialized task filled with layers of complexity that can prove difficult to execute, even when the scope of work is fully understood.
Design Methodology and Development of an Economical 3D Printer2016-01-03254/5/2016
Additive manufacturing has experienced rapid growth over a span of 25 years. Additive manufacturing involves the development of a three-dimensional (3D) object by stacking layer upon layer. Conventional machining techniques involve the removal of material. However, this technique differentiates itself from other techniques by means of addition of the material. The integration of CAD with additive manufacturing has offered the ability to create complex structures. Despite its clear benefits, additive manufacturing suffers from a high initial investment. An average cost of an entry level commercial 3D printer is 600$. A low-cost 3D printer has been designed and built for experimental investigation within a budget of 300$. The paramount process of 3D printing involves a combination of interpreting data from CAD files and controlling the motors using this data. The various design considerations while developing the 3D printer have been discussed. The 3D printer developed, provides the user with a build volume of 140*280*100 mm3. This is comparable to an entry level commercial 3D printer. The fabricated printer frame serves to absorb the vibrations and ensures optimum quality prints. The choice of motors to provide the necessary torque, the dependence of layer height on lead screw pitch and belt selection is crucial. The components involved in the construction of 3D printer will be presented and accompanied by brief commentary on the underlying principle of each component. The necessary steps involved in the calibration of the 3D printer are presented before the readers. Through this study, an insight is provided into the basic problems involved while 3D printing and their solutions.
Javed, FarhanJaved, Salman
Study of Optimization of Reciprocating Parts for General-Purpose Engine with Aluminum-Alloy Connecting Rods2015-32-080511/17/2015
The connecting rods employed in most of general-purpose engines with a power from 1.5 kW to 10 kW are manufactured from aluminum alloy in order to increase productivity and reduce weight, and therefore display lower material strength than steel connecting rods. In terms of operating conditions, general-purpose engines are frequently operated under high load while being held at a comparatively low engine speed, necessitating strength and durability in relation to combustion pressure. Realizing a balance between the rigidity of each part is an important factor in reconciling the achievement of weight reduction in the reciprocating parts while also keeping strength. The research discussed in this paper developed a structure optimization system to examine shape parameters for reciprocating parts targeting 4 kW class engines, and studied shapes that would balance the reduction of weight with the keeping of strength. These realizes design shapes of 4 kW class engines in which the stress generated on each part is equivalent to or lower than the stress generated on the mass-production shape, while reducing the mass of reciprocating parts by approximately 6% (compared to the initial shape). Investigation using reciprocating shapes of general-purpose engines with different power showed that shapes of reciprocating parts with the smallest weight had the same dimension pattern as discussed above irrespective of the cylinder bore size.
Okubo, MasamiSuzuki, Masato
An Innovative Vehicle Behaviour Modeling Methodology for Model-Based Development2015-01-01654/14/2015
Vehicle simulation models are essential throughout the development process in the automotive industry. The benefit starts when benchmarking, continues when target setting and component selection and permits model-based development of controllers and strategies to ease the calibration of the vehicle. This paper studies the suitability of different vehicle performance and consumption simulation methodologies based on longitudinal dynamics for the variety of applications on vehicle development. These methodologies can be applied to architectures ranging from quadricycles to trucks and from combustion to hybrid. The main difference between methodologies is the solver, which influences the results and the area of application. The two main trends, namely forward and backward simulation, have features that make them not suitable for all the applications. Consequently, simulation methods that combine the virtues of both for a specific objective or to a wider field of application appear in literature. This paper demonstrates that the combined methodology developed by IDIADA for the software vemSim (Vehicle Energy Management SIMulator) in Matlab/Simulink environment performs properly in all the applications during the development process. The base of the method is a solver that combines the advantages of backward and forward methods to cover the different application cases (correlation, calibration, target setting, controllers development…) with a single method. The advantage over forward is that the solver itself does not require a driver model that affects results, but it can also work together with driver models. The paper compares the different methods based on the ability to describe a target velocity profile and simulate dynamic phenomena in a reference model.
Roche, MarinaMammetti, Marco
Development of Indigenous Methodology for Design and Dynamic Analysis of Engine Valve Train System with Timing Chain Drive for High Speed Applications2015-26-00221/14/2015
In the pursuit of design and development of efficient, reliable and durable system and components for modern engines, there is a need to understand complications involved in building mathematical models for simulation. Valve train and timing drive systems are having higher rankings for addressing these attributes. Hence, a new comprehensive multi body dynamics model is built and equations are solved by state-variable approach. Model developed is validated and in order to probe into details of Hydraulic Lash Adjuster (HLA) behavior and coupled analysis of timing chain drive systems for valve train system, simulation is carried out to freeze design options. Engine timing drives used in engines are one of the most critical systems. Timing chains are preferred widely in modern high speed engines as compared to timing belts and gear drives. In spite of advantages of chain drive systems, their complex dynamic behavior is not well researched. The major objective of the current work is to design & develop timing chain drive and valve train system for a high speed three cylinder diesel engine and investigate about its durability. In this research work, dynamic model of type-2 valve train with HLA and chain drive with hydraulically operated tensioners is built in GT valve train software. The final goal is to optimize the valve train and timing system performance by simulation. The results related to timing chain analysis are expressed in terms of parameters such as contact forces, normal forces between different components and link tension etc. The effectiveness of this model calibration technique was confirmed through comparison of unit dynamic characteristics in an excitation test and a calibrated simulation. The proposed simulation process is validated experimentally and has shown considerable reduction in development time with improved robustness.
Mulik, RakeshRamdasi, Sushil S
Analysis of the Friction Losses in an Internal Combustion Engine2012-36-030310/2/2012
This work presents the results of the study of the forces involved in the rubbing friction between the moving parts of the Otto cycle internal combustion engine. In order to study the friction force, a Honda GX 35 engine was modified and a load cell was attached to its chassis. The friction forces among the internal parts of the engine were transferred to the engine chassis, and, by means of a support, to the load cell. Those forces were measured in several situations of the engine, making possible to identify the amount of friction related to each component. The total measured friction power was equal to 112W, representing about 10% of the developed power of the engine. The results obtained by the tests showed the contribution of each individual part of the engine on the friction losses. By the results, it was possible to propose modifications to reduce the total internal friction of the engine, in order to increase its efficiency. After the measurements of the friction force related to different components of the engine, new measurements were carried out in order to analyze the influence of the geometry of the pistons on the friction. During the tests, they were employed pistons with different geometries in relation to the original one. When a modified piston was employed, a reduction of up to 24% could be obtained on the values of friction when compared to those ones produced by original crankshaft - rod - piston assembly. Most of the friction energy is dissipated as heat through the coolant and lubricant. This heat is removed from the system by the water and oil radiators, so the friction losses also have great influence in the cooling system design.
Da Silveira, Marilia AmaralGertz, Luiz CarlosCervieri, AndreRodrigues, Antonio Flavio AiresSenger, Marcio
Improvements in Fuel Efficiency through Improvements in Cord Reinforcements for Timing Belts2012-01-17509/10/2012
The overhead camshaft engine efficiency can be improved by control of the rotation and phase of the cam shaft rotation. The aim of this paper is to show the improvements that have been made to the cam shaft rotation through the improvements in the timing belt, and in particular the reinforcing cords within the timing belt. The current state of the art of timing belt reinforcement is presented, and an independent study of the fuel efficiency of a modern timing belt compared to the efficiency of a fully optimised gasoline engine with a timing chain. This considers the power losses due to friction as the timing belt (or chain) transmits power from crank to cam, the power losses expressed as vibrations and noise, the variations in speed of cam rotation for different designs of timing belt, and also consistency of cam rotation through the life of the timing belt (or chain). The improvements have been quantified from engine studies of engine efficiency, engine dynamics, engine friction measurements, accelerometer studies for NVH behaviour and from these the benefits in fuel economy and CO2 emissions were quantified. Novel systems that use a timing belt running within the engine immersed in oil are discussed. These have been adopted on two engines to date, with significant interest and development projects under way. Of concern to the motorist are not only fuel efficiency but also the cost and frequency of changing a timing belt. The historical mechanisms will be discussed of the changes in timing belts that control the belt durability. The improvements in reinforcing cord design and performance that contribute to life-of-engine belts will be presented, together with cord and belt developments that increase the durability and reliability of the timing belt even further.
Stevens, Chris A.Hayes, Craig H.
A Method to Calculate the Natural Frequency of the Timing Belt Drive2011-28-014010/6/2011
A method to calculate the Natural frequency of the Timing belt drive is developed and validated. Timing belt drives are widely used in the automotive engines for valve actuation drives where accurate motion and force transmission is utmost necessary. Natural frequency is an important parameter to understand the vibration behavior of a system. Previous studies have found the Natural frequency and frequency response of the timing belt with experimental method and with FEA/ MBD software. In this study attempt has been made to develop a tool which will require basic material properties to calculate the natural frequency. Complete timing belt drive system is divided into set of standard components/elements. The belt tooth is divided in four layers and stiffness calculation is based on apparent modulus of elasticity derived from form factor. For belt pulley tooth analogy with cantilever beam is used. The model can be used for trapezoidal shaped timing belt as well as for other forms of the tooth. The belt drive level mathematical model is developed by calculating the equivalent system properties from the individual element properties. In order to reduce computational efforts a MATLAB based tool is developed. The validation is done by comparing the mathematical model with the experimental data. The predicted value from the mathematical model and experimental values are in close agreement.
Kulkarni, ChaitanyaAher, V. S.
System Automated for the Lifting Curves Camshaft2011-36-007310/4/2011
In internal combustion engines, gas exchange in the combustion chamber through the intake and exhaust are directly related to engine efficiency. The mechanical element responsible for handling and synchronization of the valves during cycles of intake, compression, combustion and exhaust, in Otto cycle engines and diesel cycle is the camshaft. Soon to know the characteristics of lift, duration, crossing, and the characteristics of velocity and acceleration of the valve assembly is very important to assess the performance of internal combustion engines. However, the engine manufacturers do not provide such features accurately, in order to avoid being easily modified or acquired by other manufacturers. And subtle changes between camshafts fitted the same engine family may promote different torque characteristics and power consumption as well as without, however, characterize a new engine. So that the lifting of curves camshafts is currently done manually, through a process and time-consuming labors, which, besides being inefficient and is prone to failure. The camshaft is positioned to be measured between two points, and this is mounted an encoder scale. A linear sensor is mounted on the lobe of the command to be lifted and the reading is taken linear displacement associated with the reading of the angular spin of the command, in order to get an admission to the curve and a curve for the leakage. Therefore generating an automated madder and fast curves of camshafts in the study, with appropriate precision.
Pereira, Thiago AntonioFontana, FilipeVandresen, MarceloCardoso, Pedro OliveiraPereira, MiltonCampos, Bruno Abdias
Increasing of Crankshaft Structural Strength by means of using non-straight bearings so called U-Shape Bearing2009-36-018810/6/2009
Nowadays, there is a demand for ICE (Internal Combustion Engines) with higher PCP (Peak Cylinder Pressure) in order to improve the engine performance and decrease the level of emissions. Due to this PCP increasing, the engine components must have higher structural strength. This work aims to perform a structural investigation of an innovative and revolutionary non-straight bearing applied to the pin journal of a crankshaft for a mid-range application (called U-Shape bearing). By using of structural optimization tools applied to this non-conventional bearing it was achieved substantial reduction of the stress concentration in the pin fillet and also substantial improvement in the crankshaft torsion stiffness, which results in a better dynamic performance regarding torsional vibration and potential for better NVH behavior. Compared with the conventional straight bearing the so called U-Shape bearing for this specific mid-range diesel application achieved an increasing in bending and torsion resistance compatible with 2015 combustion pressure levels. This mentioned non-straight bearing combined with structural optimization tools also enabled other initiatives such as crankshaft downsizing, mass reduction and consequently lower fuel consumption.
de Souza Rodrigues, AlexVillalva, Sergio GradellaGalli, Luis Antonio Fonseca
Simulation of a Valve Train Using Non-Smooth Mechanics2008-01-02914/14/2008
Nowadays, multi-body systems theory including bilateral and unilateral constraints is comparatively well established by means of set-valued force laws. Although methods of non-smooth mechanics enable a highly efficient modeling, they are not conventionally used in industrial practice. Therefore in the present paper a valve train including hydraulic elements like a hydraulic lash adjuster is modeled using above mentioned methods. A main focus is laid upon the treatment of contact problems and two different models are investigated. Contacts in multi-body dynamics are classically described using spring and damper elements minimizing penetration. This approach results in stiff differential equations with unintentional high eigenfrequencies and long computing times as well as uncertainties in the parameters for contact stiffness and damping. Whereas in rigid contact models the contact is supposed to be completely stiff leading to non-smooth systems. The contact forces are subject to set-valued force laws describing the physical properties of the contact, namely the condition of non-penetration. Thus, stiff differential equations can be avoided and efficient models of these systems are obtained. For the rigid model discussed herein, only one interpretable physical parameter describing the dissipation of energy has to be adjusted. The dynamics of the system are described in terms of a measure differential equation augmented by projection functions representing set-valued force laws. Integration is done by a half-explicit time-stepping scheme. The set-valued laws are solved by methods of convex analysis. The concepts of non-smooth mechanics are adopted to hydraulic components. Using these methods a hydraulic lash adjuster is modeled and the simulation is compared to experimental results. Finally a non-smooth model of a valve train is investigated briefly and the different contact models are compared.
Huber, RobertUlbrich, Heinz
Dynamic Modeling of Timing Belt Frictional Contact using an Explicit Finite Element Formulation2005-01-05034/11/2005
In this study, an efficient dynamic finite element model is developed for timing (also known as synchronous) belt drive systems capable of determining the transient and steady-state response of systems consisting of any number of driver and driven sprockets. For validation purposes, a two-sprocket drive is studied in detail and a comparison is made between tooth loads predicted by the finite element model and experimental data available from the literature. The drive belt is modeled using truss or beam finite elements, while the sprockets are modeled using rigid constraints. Two types of belt contact nodes are identified: tooth nodes and groove nodes. Tooth nodes experience frictionless penalty contact forces associated with radial sprocket penetration, as well as penalty contact forces associated with trapezoidal sprocket tooth interaction. Groove nodes interact frictionally with the sprocket pitch circles in regions away from the trapezoidal teeth. The resulting contact algorithms are a natural extension of previously published and validated algorithms developed for non-toothed belt-pulley contact (Leamy and Wasfy, 2002) and therefore inherit much of the previous models' accuracy and efficiency. A complete simulation tool is achieved by incorporating the model into an in-house explicit finite element code, which can maintain time-accuracy for large rotations and for long simulation times. Simulation results of the validation drive's tooth loads are shown to compare favorably with available experimental data.
Leamy, Michael J.Wasfy, Tamer M.
The Effect of Unconventional Piston Movement on SI Engine Combustion and Emissions2005-01-11704/11/2005
A major trend in current automotive research is hybridization of the power supply. This combination of electrical machine and combustion engine results, in some hybridization topologies, in a total decoupling of the combustion engine from the transmission. When the engine is decoupled from the transmission a new degree of freedom arises in engine design. The piston movement does not have to follow an evenly rotating shaft any more. It can be altered by the generator to achieve a movement found to be better from the point of efficiency or environmental concerns. Modelling work showed a potential of lowered NO emissions if the expansion could be delayed. The experimental study, conducted in a two piston Alvar engine, showed that the state of the art electrical machine (EM) propelling one of the crankshafts was too weak to change the crankshaft speed in an extent to give the fast volume changes required to change the emissions of the internal combustion engine (ICE). By running the EM at four times the speed of the dynamometer coupled to the other piston, more unorthodox volume traces were generated and differences in the emissions of the engine were found. None of the possible changed volume traces generated pressure traces showing major changes in the 10-90% heat release rate of the engine. The experiments were conducted at the limit of what the EM was able to achieve at all times.
Stenlåås, O.Erlandsson, O.Egnell, R.Johansson, B.Alm, E.Alaküla, M.Mauss, F.
Understanding of Intake Cam Phasing Effects on the Induction and Fuel-Air Mixing in a DISI Engine2004-01-19476/8/2004
Variable Cam Timing (VCT) has been proven to be a very effective method in PFI (Port Fuel Injection) engines for improved fuel economy and combustion stability, and reduced emissions. In DISI (Direct Injection Spark Ignition) engines, VCT is applied in both stratified-charge and homogeneous charge operating modes. In stratified-charge mode, VCT is used to reduce NOx emission and improve combustion stability. In homogeneous charge mode, the function of VCT is similar to that in PFI engines. In DISI engine, however, the VCT also affects the available fuel-air mixing time. This paper focuses on VCT effects on the induction process and the fuel-air mixing homogeneity in a DISI engine. The detailed induction process with large exhaust-intake valve overlap has been investigated with CFD modeling. Seven characteristic sub-processes during the induction have been identified. The associated mechanism for each sub-process is also investigated. Based on the physics of the induction process, the experimentally observed effect of cam phasing on engine manifold pressure is well understood. Both optical engine experiments and CFD modeling showed that retarding the intake cam improves the fuel-air mixing homogeneity over a wide VCT range. Dynamometer engine testing confirms the improved mixing as the CO emission decreases as the intake cam retards. Modeling revealed that the mixing improvement is not due to the overall large-scale in-cylinder flow structure, but due to the local small flow structures.
Yi, JianwenWooldridge, SteveMcGee, JeffHan, Zhiyu
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