Comparison of torsional vibration dampers in terms of the dissipated power amount

Reducing of frictional losses between moving parts of drivelines is a permanently current topic for both conventional internal combustion engines and modern hybrid or electric drives. The application of low viscosity oils leads to the reduction of friction losses of moving engine components and thus to low fuel consumption. Further measures to increase efficiency, such as reducing the oil flow rate, must also be taken into account in their effect on functional behavior. All in all, these measures place increased demands on the functionality and durability of engine components such as piston rings and plain bearings. The effects of low viscosity engine oils on piston rings and plain bearings can be evaluated using specific computational tools and newly developed test methods. Another option to reduce the power dissipation in drive units is to use a suitable torsional vibration damper type

Past and Future Practical Solutions for Torsional Vibration Damping in Vehicle Industry

In addition to material and production costs, consumption and emission limits, the requirements for performance, efficiency and space utilization must be met when it comes to the design of today's internal combustion engines for the automotive industry. As a result, three new design trends have been emerged (based on J. Pfleghaar and B. Lohmann's paper in 2013): 1. downsizing: reduction of engine size (number of pistons and stroke) for fuel and space-saving and CO2 emission reduction purposes, 2. downspeeding: reduction of engine speed to save fuel, which necessarily entails significantly higher torques being generated and transmitted in the engine, 3. turbo supercharging: increasing the pressure and compression ratio in the engine piston cylinder to cover the increased torque demand, which is accompanied by NOx gas emissions. Due to these new design trends, significant transverse, axial, and torsional oscillations can occur on the engine's crankshaft. To avoid power loss and fatigue due to the torsional oscillations, a torsional vibration damper is advised to be installed on the free end of the crankshaft or integrated into the flywheel. This review paper focuses on the possible reasons for torsional vibrations, the applied methods used to dampen them, and expected future trends

EXPERIMENTAL EVALUATION AND SIMULATION OF TORQUE TRANSMISSIBILITY FREQUENCY RESPONSE FUNCTIONS OF VIBRATION ISOLATORS AND ABSORBERS FOR DRIVETRAIN APPLICATIONS

Four studies involving torsional vibration isolation performance of automotive drivetrain components, make up this dissertation. One study features a prototype planetary torsional vibration absorber, a unique device that targets low frequency torsion modes in automotive drivetrains. Two studies feature experiments on several torque converters, clutch locked and open, to validate models of the hardware. The last study details experiments on a centrifugal pendulum absorber in a torque converter, to characterize the viscous friction while submerged in automatic transmission fluid (ATF). The enclosed studies improve the state of the art of drivetrain vibration absorbers and isolators, by introducing a new vibration absorber concept and increasing understanding of the underlying physics of torque converters, lock-up clutch dampers, and centrifugal pendulum absorbers. The design and test of the planetary torsional vibration absorber concept demonstrated the utility of a gear reduction in increasing the apparent inertia of the absorber. By increasing its apparent inertia, the device successfully attenuated a ~20 Hz mode of vibration, and used less packaging volume and mass than a traditional torsional vibration absorber of equivalent performance. Various lockup clutch designs were characterized with torque transmissibility frequency response function (TTFRF) measurements while spinning at simulated vehicle operating conditions. This in situ testing lent itself useful in characterizing the speed dependent friction in a lockup clutch damper, while also confirming other damper parameters—like stiffness and damping. The torque converters were also tested in open mode (lockup clutch not engaged). The open mode testing revealed that the hydrodynamic torque converter transmits enough torsional vibration to excite the damper mode for the turbine damper architectures. The open clutch testing contributes a complete data set—encompassing a wide range of speed ratios—to verify torque converter models with. When comparing the test TTFRFs to model TTFRFs, a discrepancy in the damper mode’s natural frequency was revealed, and it was hypothesized that this error resulted from a reflected inertia effect of the ATF undergoing toroidal flow. The locked clutch testing provoked some questions about the centrifugal pendulum absorber (CPA)—a component of one of the tested torque converter clutch dampers. To validate an existing CPA model, and to characterize the equivalent viscous damping of the CPA mechanism, TTFRFs of custom made torque converters were measured. The custom hardware included: pinned damper (CPA active), pinned CPA (damper active), and pinned straight spring (CPA and arc spring active). The torques due to friction and viscous damping of the damper were effectively eliminated from the CPA, and the equivalent viscous damping of the CPA characterized

Nonlinear model of rubber torsional vibration damper

Linear models of rubber torsional vibration dampers do not consider the non-linear properties of rubber, and most of those, which take this feature into account, are troublesome or even impossible to use in the design and optimization process. In this paper the authors propose a nonlinear model of damper, which can assist engineers in designing

Torsional vibration analysis of crank train with low friction losses

High level of mechanical efficiency is exacted from internal-combustion engines. The reduction of friction losses of crankshaft main bearings can significantly contribute to the enhancement of this efficiency. For this purpose, an innovative design of a crankshaft is developed. The potential of computational modelling during the development of this innovative crank train is described in the article. The dynamics of the whole crank train is solved by using a multi-body system software, where flexible finite-element bodies along with hydrodynamic bearings are incorporated. Regarding the simulation results, attention is paid to the torsional vibration and its analysis, including concept design of a torsional damper, because a reduction of friction losses is associated with the improvement of torsional vibration in this case

Feasibility of A Permanent Magnet Eddy Current Torsional Damper For Large Horsepower Reciprocating Compressors

This study examines a potential compressor package to determine whether a permanent magnet eddy current damper could feasibly address compressor crankshaft torsional vibration concerns. This is done by modeling the forced response over a range of operating speeds using lumped stiffness and inertia values, compressor torque curves, and varying approximated damper properties. The predicted forced response for the 23 degree of freedom system is found by resolving the equations of motion using MATLAB’s fourth-fifth order Runge-Kutta variable time step routine. Damper dimensions are estimated based on available space inside the compressor crankcase. Damper properties are approximated assuming a conducting disc connected to the crankshaft surrounded by two freely rotating annulus magnetic arrays. Solutions obtained indicate that for this compressor package a PMEC damper has the potential to reduce compressor crankshaft vibrations with the effectiveness primarily depending on the strength of the magnetic field and the area of the conducting disc that interacts with the magnetic field

PRELIMINARY SELECTION OF BASIC PARAMETERS OF DIFFERENT TORSIONAL VIBRATION DAMPERS INTENDED FOR USE IN MEDIUM-SPEED DIESEL ENGINES

In the development and application of highly dynamic mechanical systems, major problems can arise from usually unwanted accompanying processes, such as torsional vibrations. The internal combustion engine is a typical dynamic system with a high probability of fracture of a system part due to the effects of torsional vibrations. In engineering practice, the IC engine crankshaft fracture due to torsional vibrations is prevented by using additional devices that allow the transfer of critical vibration modes of the crankshaft out of the IC engine operating range, or devices damping the resulting twist angle amplitudes. This paper presents a possible approach to defining parameters of torsional oscillatory systems of IC engines needed for a preliminary selection of basic parameters of various types of torsional vibration dampers, such as the elastic damper, the balance weight damper and the dual mass flywheel. The proposed physical and mathematical models and methods of defining the input parameters were compared with experimental results

Investigation of torsional vibration of unconventional crank train

This article presents the potential of computational modelling during the development of an unconventional crank train. The computational model is assembled as well as numerically solved in a Multi-Body System incorporating the modally reduced bodies and hydrodynamic bearings. Regarding the simulation results, the attention is paid to the torsional vibration and its analysis, including concept design of a torsional damper

Dynamics of Torsional Vibration Damper (TVD) pulley, implementation of a rubber elastomeric behavior, simulations and experiments

International audienceIn this work, the Torsional Vibration Damper (TVD) rubber ring viscoelastic-material properties are determined based on Dynamical Mechanical Analysis (DMA) measurements and master curves reconstructions using thermo-simplicity principle. The elastomeric constitutive behavior is then implemented in the torsional vibration damper's equation of motion and the frequency response is simulated so that enhanced physical representation of the TVD dynamics can be achieved. Major differences in the TVD frequency response are highlighted and analyzed whether or not the viscoelastic material properties (elasticity modulus and damping) are considered constant or frequency and temperature dependent

Torsional vibration absorbers in heavy-duty truck powertrains

The heavy-duty vehicle manufacturers face large challenges when it comes to reducing CO2 emissions from vehicles. The ongoing development of more efficient combustion engines leads to an increase in torsional vibrations. Experience within the industry indicates that the conventional single mass flywheel (SMF) and clutch will not be enough to protect the gearbox and rear driveline from engine induced vibrations in the future; more advanced technology will be needed.The work presented in this thesis focuses on simulation and analysis of torsional vibration absorbers for heavy-duty truck applications. Different multiple-mass flywheels are analysed, including dual mass flywheels (DMFs), power split vibration absorbers (PSVAs) and DMFs combined with tuned vibration absorbers (TVAs). DMFs have been used in smaller vehicles for many years, but the use in heavy-duty commercial applications is to date very limited. The other two vibration absorbers studied in this work have not yet been industrialised.The vibrations absorbers are analysed by means of simulations. Methodologies for efficient simulations in time- and frequency-domain have been developed and are presented in the thesis. The frequency-domain methods used include the harmonic response and a harmonic balance method, combined with an arc-length continuation scheme. For models with many gap-activated springs, a time-domain approach is proposed, where the dynamics problem is reformulated as a linear complementary problem (LCP).A detailed DMF model, including internal parts, friction and clearances, is presented for time-domain studies requiring high accuracy. The model is correlated based on test rig measurements.The torsional vibrations in typical heavy-duty truck powertrains with the different multiple-mass flywheels are simulated in a large engine load and speed range. The results are analysed and compared to corresponding conventional powertrains. It is evaluated how different design parameters affect the torsional vibrations and the feasibility of the concepts for heavy-duty use is studied. The simulations show that the torsional vibration amplitudes are generally significantly lower with a DMF than with an SMF, but under some conditions significant resonance excitation can occur. The PSVA and DMF equipped with a TVA can reduce vibrations further than a corresponding DMF within limited speed ranges, but lead to higher vibration amplitudes outside these ranges