Dual Mass Flywheel Research Articles

THE CHANCES FOR REDUCTION OF VIBRATIONS IN MECHANICAL SYSTEM WITH LOW-EMISSION SHIPS COMBUSTION ENGINES

Development of diesel engines is focused on reduction of exhaust gas emissions, increase of efficiency of the fuel mixture combustion and decrease of fuel consumption. Such engines are referred to as low-emission engines. Low- engines trends bring higher engine power outputs, torques and also increase of vibrations and noisiness level. In order to reduce these vibrations of diesel engines, it is necessary to apply different dynamical elements, which are able to increase an adverse impact of exciting amplitudes. One of the results is application of a pneumatic dual-mass flywheel. The pneumatic dual-mass flywheel is a dynamical element that consists of two masses (the primary and the secondary mass), which are jointed together by means of a flexible interconnection. This kind of the flywheel solution enables to change resonance areas of the mechanical system which consequently leads to reduction of vibrations.

Dual Mass Flywheel Parameter Identification

Abstract Reducing emissions brings changes in the design of internal combustion engines and thus new challenges for dual-mass flywheels (DMF) in terms of Noise Vibration and Harshness (NVH). The first part of the article describes a simple model of a centrifugal pendulum. Consequently, a more complicated DMF dynamic model involves friction between the spring components. The second part of the article deal with the multibody model of DMF using a CAD model. The dynamic model consists of a torsion spring and two bodies. The model is compared with the experimental method, which is also described in the paper.

Numerical Studies on the Stiffness of Arc Elliptical Cross-section Helical Spring Subjected to Circumference Force

Due to its excellent properties, elliptical cross-section helical spring has been widely used in automobile industry, such as valve spring, arc spring used in Dual Mass Flywheel and so on. Existing stiffness formulae of helical spring remain to be tested, and stiffness property of elliptical cross-section arc spring has been little studied. Hence, study on the stiffness of elliptical cross-section helical spring is significant in the development of elliptical cross-section helical spring. This paper proposes a method to study the stiffness property of elliptical cross-section helical spring that the experiment design method is adopted with finite element analysis. Firstly, the finite element analysis method was used to verify the cylindrical (circular cross-section and elliptical cross-section) springs. Then, the regression formula was designed and derived compared with the reference springs’ stiffness formulae by experimental design. Last, regression formula was verified with existing experiment data. The novelty in this paper is that simulation technology of arc spring was investigated and a stiffness regression equation of arc elliptical cross-section spring was obtained using orthogonal regression design, with significance in wide use of the arc elliptical cross-section helical spring promotion.

Dynamic Characteristics Analysis of a Circumferential Short Spring Dual Mass Flywheel with the Influence of Centrifugal Force and Friction

Multiple sets of spring, spring seat structures are uniformly arranged in circumferential short spring dual mass flywheel (DMF), which generally have a symmetrical structure. The internal springs and spring seats are constrained by the shape of the primary flywheel and the secondary flywheel. At different rotational speeds, the springs and spring seats have different centrifugal forces. To study the dynamic characteristics of the DMF including torque and stiffness with considering the influence of centrifugal force and friction, the discrete method is used to analyze the mechanical actions of the transmission parts in DMF. The torque action between the spring seat and the secondary flywheel is deduced. The dynamic characteristics of the DMF are obtained through analyzing and calculating. Due to the symmetry of the structure, the torque transmitted and the stiffness of the DMF also have specific symmetrical characteristics. Namely, at two relative rotational angles of the same magnitude and opposite direction, the magnitude of the transmitted torque is the same, the direction is opposite. The magnitude and direction of stiffness are the same. The influence of speed, friction coefficient, spring mass, and spring seat mass on the torque and stiffness characteristics are analyzed. Finally, the theoretical analysis is proved to be valid by the torque characteristics test of DMF.

Research on the torsional vibration performance of a CVT powertrain with a dual-mass flywheel damper system

Continuously variable transmissions (CVTs) can achieve continuous changes in speed ratio and can better improve the ride comfort of the car. However, the torque fluctuation of the engine will reduce its transmission efficiency, and the torsional damper is usually matched to improve transmission efficiency and reduce vibration noise. In this paper, the model of a complete vehicle power transmission system was established by using the bond graph method. The relationships between each state variable were obtained according to the system causality and the direction of the power flow, based on which the dynamic model of the entire vehicle power transmission system was derived. A simulation of the powertrain with dual-mass flywheel-continuously variable transmission (DMF-CVT) was carried out, and the torsional stiffness of the dual-mass flywheel (DMF) was optimized. Taking a certain sport-utility vehicle (SUV) as the test bench, the vehicle road testing of the DMF before and after improvement was carried out, and the test results before and after the improvement were compared to verify the correctness of the optimization direction, which provided a reference for the matching and optimization design of the DMF-CVT power transmission system.

Multi-objective optimization of a dual mass flywheel with centrifugal pendulum vibration absorbers in a single-shaft parallel hybrid electric vehicle powertrain for torsional vibration reduction

This research deals with an optimization of a dual mass flywheel (DMF) with centrifugal pendulum vibration absorbers (CPVAs) used in a single-shaft parallel hybrid electric vehicle (HEV) powertrain for the reduction of the torsional vibration at the rotor of the electric motor and the total moment of inertia of the DMF and CPVAs. Unlike the previous studies, this research considers the overall behavior of an entire powertrain with an in-line four-cylinder engine and a five-speed automatic transmission for the optimization of the DMF with CPVAs. For this purpose, the multibody dynamics model of the HEV powertrain is constructed and used to analyze the transient response of the system for a given gas pressure map and acceleration condition of the vehicle. Then, a multi-objective genetic algorithm is applied to determine the Pareto optimal front that yields the design parameter values of the DMF and CPVAs effective in the torsional vibration reduction and inertia minimization. The result of the optimization is compared with the HEV powertrain system with a flywheel only, and shows that the vibrations transmitted to the motor are significantly reduced in all the solutions of the Pareto front. By using the method proposed in this research, various parameter combinations of the DMF and CPVAs can be considered in the early design process.

Characterization of the torsional vibration behavior of circular and rectangular cross-sectional arc springs: Theory and experiments

Abstract This paper is about the theoretical and experimental characterizations of the torsional vibration behavior of circular and rectangular cross-sectional arc springs. Firstly, the dynamic behaviors of arc springs with different cross-sectional wire profiles designed for a dual mass flywheel are modeled by mathematical formulations. After that, experimental tests are performed to verify these models and it is observed that the stiffness characterizations are in good agreement with experimental results. Lastly, the masses of two different arc springs are compared by regarding the same vibration stiffness criteria and it is demonstrated that the rectangular wire provides an arc spring with a 9.44 vol.-% lighter structure. Thus, the outcomes of this paper can be good references for the manufacturer about the numerical and experimental characterization of dual mass flywheel springs, especially for rectangular wire arc springs.

An Improved Design of the Engine Bench Test Tool for the Dual Mass Flywheel (DMF)

At present, a lot of passenger cars and light trucks are equipped with the dual mass flywheel, which can decrease the non-uniformity of the indicated engine torque. In engine bench test, the secondary mass of the dual mass flywheel can’t be fixed because there is no transmission system on the test bench. As a result, the secondary mass of the dual mass flywheel will have radial and circumferential movements, which may lead to a damage to the dual mass flywheel. This paper presents an improved design of the crafting tool for the dual mass flywheel to protect the secondary mass during the engine bench test. For the improved design, the cylinder body is used for the positioning of the crafting tool, and a spline shaft and a ball bearing of centripetal adjustment are chosen to fix the secondary mass. Through this tool, the dual mass flywheel engine can be tested on the test bench without a starting shaft, and the disassembling of the engine flywheel bolts during the hot test can be avoided.

Dynamic Model and Dynamic Response of Automobile Dual‐Mass Flywheel with Bifilar‐Type Centrifugal Pendulum Vibration Absorber

Compared with dual‐mass flywheel (DMF) and DMF with simple‐type centrifugal pendulum vibration absorber (CPVA), DMF with bifilar‐type CPVA has a better damping performance in the whole speed range of engine. The related research mainly focused on local models, such as dynamic model of DMF and dynamic model of CPVA, and the effect of the curvature path of CPVA on the damping performance. The reported models and methods are not sufficient for the system of DMF coupled with bifilar CPVA. Aiming at the deficiency of local models and the limitation of bench test, an integral model for DMF with bifilar CPVA is proposed and the real vehicle test is carried out in this study. Involving the moment of inertia of the centrifugal pendulum, the model considers the nonlinearities of DMF and bifilar CPVA. Afterward, the dynamic model of the automobile power transmission system equipped with the DMF with bifilar‐type CPVA is built, and the dynamic responses of the system are investigated under idling and driving conditions. According to the simulation results, DMF with bifilar‐type CPVA shows better vibration reduction performance in full‐speed range. Moreover, the key structural parameters R and l influencing the damping performance of DMF with bifilar CPVA are discussed. The results show that the sum of R and l is directly proportional to the damping effect. Finally, real vehicle tests under idling and driving conditions (engine speed from 750 r/min to 3400 r/min) are carried out. The test results show that the 2nd order engine speed fluctuations are attenuated by more than 80% by DMF with bifilar CPVA with engine speed lower than 2000 r/min and are attenuated by more than 90% with engine speed higher than 2000 r/min. The experimental results are basically consistent with the simulation results, which verify the validity of the model.

Torsional vibrations in heavy-duty truck powertrains with dual mass flywheels

Many of the measures taken to improve combustion engine efficiency lead to higher torsional vibrations. For heavy-duty commercial vehicles it is foreseen that the conventional flywheel and clutch will not be able to sufficiently reduce those increased engine torsional vibrations to the driveline. In this paper, the steady-state torsional vibrations in a heavy-duty truck powertrain are studied. The focus is engine excited vibrations at high load within operating speed range. Vibration phenomena in a conventional heavy-duty powertrain and in powertrains equipped with dual mass flywheels are studied. It is shown how the use of a dual mass flywheel can enable down-speeding and increased engine torque with maintained or reduced levels of torsional vibrations.

Torsional vibrations in heavy-duty truck powertrains with dual mass flywheels

Torsional vibrations in heavy-duty truck powertrains with dual mass flywheels

Modeling of multistage nonlinear Dual Mass Flywheel torsional damper based on smoothing function fitting

The smoothing function is used to solve the problem of low simulation efficiency of multi-stage stiffness Dual Mass Flywheel (DMF) model, and the influence of different smoothing functions and fitting factor β on the fitting effect is studied. Firstly, based on the analysis of the working principle of multi-stage stiffness DMF, a mathematical model of DMF considering multi-stage stiffness and damping nonlinearity is established, and the accuracy of the model is verified by bench test. Then, tanh function, arctangent function, and sigmoid function are used to smooth the segment points in the DMF model, which solves the problem of inefficiency and not easy to converge in simulation. Finally, a 3-DOF model of the transmission system with DMF is established to simulate and analyze the smooth effect of the smoothing function and the performance difference between different smoothing functions. The results show that the smoothing function can effectively improve the stability of the simulation model. By comparing the three smoothing functions, it can be seen that the sigmoid function has the most obvious effect, which can shorten the simulation time by 52%.

Weight-Vibration Pareto Optimization of a Triple Mass Flywheel for Heavy-Duty Truck Powertrains

Enhanced efficiency of heavy-duty truck powertrains with constraints imposed on noise, vibration, and harshness requires novel solutions for torsion vibrations attenuation. In the paper, the weight-vibration Pareto optimization problem for a novel vibration absorber, a triple mass flywheel, for application in heavy-duty truck powertrains is considered. Global sensitivity analysis and Pareto optimization method are used to design a novel vibration absorber. The optimization method attempts to minimize oscillations of the torque at the transmission input shaft as well as to minimize total mass inertia of the absorber. It is shown that there exists a Pareto front between the measure of the attenuation of oscillations of the torque and the total mass inertia of a triple mass flywheel. The optimized design parameters for the absorber are obtained that provide the best attenuation of oscillations of the torque at the transmission input shaft for different mean values of the engine driving torque. The analysis shows real evidence of the feasibility of the application of this concept of vibration absorbers in heavy-duty truck powertrains. It is also shown that optimized design parameters of a triple mass flywheel put this concept in a superior position in comparison with a dual mass flywheel.

Research on dynamic behavior of torsional absorber in powertrain system considering nonlinear factors

The influence of nonlinear factors on the dynamic behavior of the powertrain torsional damper is studied by using the average method. First, the structure and working principle of dual mass flywheel are analyzed, and the nonlinear dynamic model of dual mass flywheel is established. Then the frequency response curve is obtained by the average method, and the accuracy of the solution is verified by the RK4 method. Finally, the effect of the parameters of dual mass flywheel on the amplitude–frequency characteristics is studied. The results show that the average method is suitable for the nonlinear vibration analysis of the dual mass flywheel, and the amplitude–frequency characteristic curve of the system has the characteristics of turning to the high frequency at the segment. Reducing the excitation amplitude, increasing the viscous damping, or increasing the Coulomb friction damping can effectively reduce the resonance peak value of the dual mass flywheel, and increasing the angular clearance is beneficial to further reduce the resonance frequency of the dual mass flywheel.

Influence of single and dual mass flywheel usage in IC engines on clutch dynamics

The dual mass flywheel especially used in diesel engines has a structure in which the single- mass flywheel is divided into two parts and these two parts are combined with a curved helical spring. The flywheel is a part that reduces the speed fluctuations in the crankshaft of the internal combustion engines. In addition to this function, the dual mass flywheel dampens the torsional vibrations better than the clutch disc springs thanks to the spring system found in its structure. There are no torsional springs in the disc of the clutch system where dual mass flywheel is used. The dual mass flywheel is used with a rigid clutch disc without torsion springs. From this point of view, it is thought that the clutch dynamics of both systems are different. For this purpose, mathematical models of both systems were formed. The obtained models were solved after the appropriate transformations. As a result, it was seen the clutch engagement times are almost same in both systems. However in the clutch system where the dual mass flywheel is used the clutching process is performed more smoothly.

Coordinated clutch slip control for the engine start of vehicles with P2-hybrid automatic transmissions

The disconnect clutch can be used to start the engine through slipping for vehicles having P2-hybrid automatic transmissions. However, the driver is easily disturbed by the starting process because of driveline vibration. We develop a multiphase control strategy for slip coordination between the disconnect clutch and shifting clutch to improve the driving comfort during engine start. A detailed dynamic model of the whole powertrain, including the engine (ICE), P2-hybrid automatic transmission, dual-mass flywheel (DMF), electric motor (EM), and driving resistance, is established to support the development of the control strategy and analyze the transient behavior of the engine starting process. Simulations are performed using a co-simulation platform based on “SimulationX” software for the dynamic model and “Simulink” software for the developed control strategy. Experiments are carried out on a plug-in hybrid vehicle. Both simulation and experiment results show that the driveline oscillation can be effectively reduced through slip coordination between the disconnect clutch and shifting clutch.

Analysis of power split vibration absorber performance in heavy-duty truck powertrains

The current development of more efficient combustion engines leads to an increase in engine torsional vibrations; therefore, new technology is needed for reducing the vibrations transmitted from the engine to the driveline. In this article, the concept of power split vibration absorber is evaluated. A mathematical model of the power split vibration absorber is presented, and an analytical study shows how different design parameters affect the power split vibration absorber performance. Numerical simulations with models representing typical heavy-duty truck powertrains are used in the evaluations. It is concluded that for a low level of damping, the power split vibration absorber can provide significantly lower vibration amplitudes than a corresponding dual mass flywheel within a limited speed range. If the power split vibration absorber is optimised for the critical low engine speeds, an overall decrease in the level of vibration can be obtained, but a larger installation space than with a conventional dual mass flywheel would probably be required.

Dual-mass flywheels with tuned vibration absorbers for application in heavy-duty truck powertrains

As the heavy-duty combustion engine development goes towards lower rotational speeds and higher cylinder pressures, the torsional vibrations increase. There is therefore a need to identify and study new types of vibration absorbers that can reduce the level of torsional vibrations transmitted from the engine to the gearbox. In this work, the concept of a dual-mass flywheel combined with a tuned vibration absorber is analysed. The tuned vibration absorber efficiently reduces the vibration amplitudes for engine load frequencies near the tuning frequency, but it also introduces an additional resonance into the system. By placing the tuned vibration absorber on an intermediate flange between the two dual-mass flywheels, the introduced resonance frequency will be lower than the tuning frequency and a resonance in operating engine speed range can be avoided. Numerical simulations are used to show how the torsional vibration amplitudes in a heavy-duty truck powertrain are affected by the tuned vibration absorber and how the different parameters of the tuned vibration absorber and the dual-mass flywheel affect the torsional vibrations and the resonance frequencies.

The requirements for the design of dual-mass flywheels

In the modern powertrains with new low emission combustion engines, the effort to reduce emissions and weight of the entire system increase the efficiency of vehicle drives but also make the drive much more sensitive to vibration. The new design concepts of dual-mass flywheels offer more options for eliminating vibration in vehicle drive systems. Every design of the dual-mass flywheel must ensure that it has the appropriate characteristics. A suitable characteristic then creates a prerequisite for application in a drive in which the resonance area can be moved to very low operating speed.

Research on Damping Performance of Dual Mass Flywheel Based on Vehicle Transmission System Modeling and Multi-Condition Simulation

In this paper, the reduction of vibration of dual mass flywheel (DMF) torsional damper under multiple working conditions is studied. Firstly, a 6DOF non-linear transmission system model including engine, DMF, gear pair of gearbox and clutch friction model is established. Secondly, a comprehensive multi-condition simulation strategy including ignition condition, idle condition, startup condition, drive condition, uniform speed condition and coast condition is designed to study the vibration reduction performance of DMF under different conditions. Then, the accuracy of the 6DOF non-linear transmission system model is verified. The simulation and test results showed that the accuracy of the model meets the engineering requirements. Finally, the effects of the performance parameters of the DMF on the torsional vibration of the transmission system under various operation conditions are studied. The results show that the performance of DMFs varies significantly under different conditions, and under drive condition the DMF has the best performance of vibration reduction. The free angle has less impact on the damping performance of the DMF, but other parameters have greater influence. The influence trend of the same parameter on the vibration reduction performance of DMF is different under different working conditions. Therefore, the parameter matching of the DMF cannot be based on one driving condition. It is necessary to comprehensively consider the vibration damping performance of the vehicle powertrain under multi-condition to match the parameters.