1,721,379 research outputs found
ADVANCES IN THE AUTOMOTIVE SYSTEMS: AN OVERVIEW OF DUAL-CLUTCH TRANSMISSIONS
No full textAfter a brief description of the most important “automatic” solutions, this paper explores the advantages of
automated manual ones, particularly in the dual-clutch transmission (DCT) configuration. This mechanical architecture
offers gear shifts without interruption of power (the so-called “torque gap”), by applying the engine torque to one clutch
just as the engine torque is being disconnected from the other one. The result is jerk-free gear change with the same
driving style found in a conventional automatic combined with the efficiency of a manual transmission. It is as smooth as
the most automatics, but more economical; it is as easy to drive as a standard auto, faster and more responsive than even
the sportiest manual gearbox. The two clutches are engaged alternatively in different speeds and power transmission
continues during a shift through the control of clutch slippage. This outstanding design allows automakers to achieve what
previously had seemed impossible: to improve both comfort and sportiness, whilst at the same time fulfilling the essential
requirement of reducing fuel consumption. Historical evolution, future market forecast and recent patents complete the
paper, while recent modelling approaches and proposed control strategies are referenced
Meet the editorial board member
No full textEditorial board member profile: Ph.D. in Tribology, University of Pisa (I), March 2002. Graduated (M.Sc. Degree) in Mechanical
Engineering “summa cum laude”, University of Salerno (I), March 1998. Since 2002, he has been
serving as a teacher of Mechanical/Industrial Measurements and (since 2004) Mechatronics.
Associate Professor at the Department of Industrial Engineering, University of Salerno.
Research fields: Lubrication modelling, lubrication in the internal combustion engines: hydrodynamic
and mixed lubrication for piston rings, piston lateral dynamics, models for friction power loss
assessment, piston slap prediction. Effects of nanoparticles as friction reducer additives. Friction interaction
modelling, frictional torque transmission of automated dry clutch and dual-clutch transmissions.
Model based control for automatic transmissions. Rotordynamics: hydrodynamic lubrication in journal
bearings, couple stress fluids effects; rotor stability. Vibration measurement methods: effects of rotation on disk and beam vibrations
EFFECTS OF PISTON LATERAL DYNAMICS ON THE TOP RING NON-AXISIMMETRY HYDRODYNAMIC LUBRICATION
No full textDRIVETRAIN VIBRATIONS EXCITED BY DRY CLUTCH IN AUTOMATED MANUAL TRANSMISSIONS
No full textThe synergy between engine and clutch control in modern mechatronic transmissions as Automated Manual Transmission (AMT) and Dual Clutch Transmission (DCT) in passenger car aims at delivering power to the road during launch and gearshift transients in a way able to provide high riding quality. Engine and transmission control systems could provide ideal control of the three discontinuities of speed, torque and inertia variables during shifting of clutch only through the knowledge of the drivetrain dynamics and the frictional conjunction between its subparts. The simulations carried out in this paper aim at studying the excitation of drivetrain torsional vibration caused by frictional actions during the slip phase of the clutch engagement in automated manual transmissions. The results of this work substantiate the excitation of torsional motion in gear shifting operations in the characteristic frequency range of the "eek noise". Such outcomes underline the need to include the clutch cushion spring behavior in the simulation of all the phenomena induced by vibration originated at clutch level
MEASURING THE NATURAL FREQUENCIES OF CENTRIFUGALLY TENSIONED BEAM WITH LASER DOPPLER VIBROMETER
No full textThis paper describes the experimental investigation on lateral vibrations of a rotating uniform Euler–Bernoulli beam
that is doubly symmetric in cross-section. Several theoretical studies have been directed to the evaluation of natural frequencies
of rotating structural elements such as space frames, windmill rotors, aircraft propeller, etc. In this paperwork,
a technique to simulate the presence of centrifugal force acting on the uniform beam is presented while the data about the
tested material and the measurement facilities are provided. The results are in excellent agreement with the theoretical predictions
about the second and third natural frequencies
MEASUREMENT OF THE NATURAL FREQUENCIES OF A UNIFORM ROD LOADED WITH CENTRIFUGAL FORCES USING A LASER DOPPLER VIBROMETER
No full textAn experimental investigation of transverse vibrations in a rotating uniform plate, possessing double symmetry in the transverse cross section, is described. A method of modeling the centrifugal force acting on a uniform plate (under static conditions) and measurement details are presented. Test data are given.
The results obtained agree well with calculations of the natural frequencies for the second and third harmonics of natural oscillations
VIBRATIONS INDUCED BY ELECTRO-ACTUATED DRY CLUTCH IN THE EEK FREQUENCY: EXCITATION IN GEAR-SHIFTING OPERATIONS
No full textIn Automated Manual Transmissions (AMTs) the clutch control strategies to manage the engagement operation and clutch vibrational behaviour are mutual interdependent and only an optimized mechatronic design could lead to an effective target from several points of view: passengers' comfort, fuel economy, system reliability, performance, driving feeling, etc.
In fact, noise, vibration and harshness (NVH) phenomena are crucial subjects in the modern automotive industry. In passenger car equipped with automatic transmissions the electronic management of the coupling between engine and transmission couldn’t provide sensible improvement of comfort and overall vehicle performance during gearshifts without the availability of dependable models of the flywheel, clutch and driveline as powerful tools for vehicle design engineers.
In this paper, simulations of driveline vibrational behaviour have been performed by implementing a high-order multi-body model for the dry clutch mechanism with the purpose of studying the excitation of torsional vibration caused by frictional actions during the slip phase of the clutch engagement in manual or automated manual transmissions. The analysis aims at deepen about the coupling between pressure plate wobbling and torsional motions in order to improve the current understanding of the
excitation mechanisms in the frequency region of the so-called “eek noise”, 250-500 Hz.
The results of this work substantiate that enhancing of torsional motion in the characteristic frequency range of the eek effect occurs in vehicle launch and gear shifting operations regardless of the rigid wobbling motion of the pressure plate. Such outcomes underline the need to include the non-linear characteristic of the clutch cushion spring in the simulation frictional induced vibration originated at clutch level.
Simulations of gear-shifting operations have been carried out by applying ramp profiles to the clutch throwout bearing according to the requirements of typical manoeuvres in passenger cars
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