Dynamic Analysis of a Serpentine Belt Drive With a Decoupler/Isolator

2004 ◽  
Author(s):  
Raghavan Balaji ◽  
Eric M. Mockensturm
Keyword(s):  
Dynamic Tension ◽  
Automotive Engine ◽  
Belt Drives ◽  
Front End ◽  
Steady State Operation ◽  
Serpentine Belt ◽  
Excitation Dynamic ◽  
Linearized System ◽  
Angular Displacements ◽  
Rotational Response

Belt drives employing a single, flat serpentine belt tensioned by a passive tensioner are found in automotive engine Front End Accessory Drive (FEAD) where the crankshaft supplies power to accessories like alternators, air-conditioning compressors, pumps, etc. [1]. When the FEAD undergoes forced vibration due to crankshaft excitation, dynamic tension fluctuations can cause the belt to slip on the accessory pulleys [2]. The probability of belt slip increases with the peak drop in belt tension over the pulley during steady state operation [3]. In this paper, one possible solution is analyzed, using a decoupler to isolate/separate the accessory inertia (e.g. alternator) from the FEAD system. This is achieved by placing between the pulley and the accessory a combination of a one-way rigid clutch and an isolator spring. In this study, the rotational response of a typical FEAD is extended to include the clutch and isolator. An analytical solution is then obtained by considering it as a piecewise-linearized system moving about an equilibrium angular displacements. The performance of the ordinary FEAD with regard to tension fluctuation is then compared to that of the system equipped with a decoupler/isolator. The results obtained indicate that within the practical working range of engine speeds, use of either an isolator or a decoupler-isolator could significantly lower the dynamic tension drop across the accessory pulley.

Piece-wise linear dynamic analysis of serpentine belt drives with a one-way clutch

2008 ◽  
Vol 222 (7) ◽  
pp. 1165-1176 ◽  
Author(s):  
F Zhu ◽  
R G Parker
Keyword(s):  
Relative Velocity ◽  
Power Transmission ◽  
Design Guidelines ◽  
Computational Time ◽  
System Response ◽  
Dynamic Tension ◽  
Belt Drives ◽  
Serpentine Belt ◽  
The One ◽  
Clutch Torque

A prototypical three-pulley serpentine belt drive with belt bending stiffness is extended to include a one-way clutch in order to understand the non-linear dynamics of the system with the one-way clutch performance. The clutch is modelled based on the relative velocity of the driven pulley and its accessory. The clutch locks (engages) the pulley and accessory for zero relative velocity and produces a positive inner clutch torque. Zero clutch torque initiates clutch disengagement, allowing unequal velocities of the two components. This model leads to a piece-wise linear system. The transition matrix is used to evaluate the system response in discrete time series for the two linear configurations, saving significant computational time. The system dynamics including response and dynamic tension drop are examined for varying excitation frequencies, inertia ratio of the pulley and accessory, and external load. The investigation of vibration reduction because of the single-direction power transmission of the clutch provides design guidelines in practice.

Periodic Response of Front End Accessory Drives With Dry Friction

1997 ◽  
Author(s):  
Michael J. Leamy ◽  
Noel C. Perkins
Keyword(s):  
Dry Friction ◽  
Equations Of Motion ◽  
Harmonic Excitation ◽  
Stick Slip ◽  
Automotive Engine ◽  
Belt Drives ◽  
Wide Range ◽  
Serpentine Belt ◽  
Incremental Harmonic Balance ◽  
Nonlinear Equations Of Motion

Abstract Belt drives have long been utilized in engine applications to power accessories such as alternators, pumps, compressors and fans. Drives employing a single, flat, ‘serpentine belt’ tensioned by an ‘automatic tensioner’ are now common in automotive engine applications. The automatic tensioner helps maintain constant belt tension and to dissipate unwanted belt drive vibration through dry friction. The objective of this study is to predict the periodic rotational response of the entire drive to harmonic excitation from the crankshaft. To this end, a multi-degree of freedom incremental harmonic balance (IHB) method is utilized to compute periodic solutions to the nonlinear equations of motion over a wide range of engine speeds. Computed results illustrate primary and secondary resonances of accessories and tensioner stick-slip motions.

Dynamic Modeling of Belt Drive Systems: Effects of the Shear Deformations

2006 ◽  
Vol 128 (5) ◽  
pp. 555-567 ◽  
Author(s):  
Andrea Tonoli ◽  
Nicola Amati ◽  
Enrico Zenerino
Keyword(s):  
Belt Drive ◽  
Automotive Applications ◽  
Axial Deformation ◽  
Shear Deformations ◽  
Viscous Term ◽  
Rubber Layer ◽  
Belt Drives ◽  
Serpentine Belt ◽  
In Series ◽  
Drive Systems

Multiribbed serpentine belt drive systems are widely adopted in accessory drive automotive applications due to the better performances relative to the flat or V-belt drives. Nevertheless, they can generate unwanted noise and vibration which may affect the correct functionality and the fatigue life of the belt and of the other components of the transmission. The aim of the paper is to analyze the effect of the shear deflection in the rubber layer between the pulley and the belt fibers on the rotational dynamic behavior of the transmission. To this end the Firbank’s model has been extended to cover the case of small amplitude vibrations about mean rotational speeds. The model evidences that the shear deflection can be accounted for by an elastic term reacting to the torsional oscillations in series with a viscous term that dominates at constant speed. In addition, the axial deformation of the belt spans are taken into account. The numerical model has been validated by the comparison with the experimental results obtained on an accessory drive transmission including two pulleys and an automatic tensioner. The results show that the first rotational modes of the system are dominated by the shear deflection of the belt.

Complex modal analysis of serpentine belt drives based on beam coupling model

2017 ◽  
Vol 116 ◽  
pp. 162-177 ◽  
Author(s):  
Yue Pan ◽  
Xiandong Liu ◽  
Yingchun Shan ◽  
Gang(Sheng) Chen
Keyword(s):  
Modal Analysis ◽  
Coupling Model ◽  
Belt Drives ◽  
Beam Coupling ◽  
Serpentine Belt ◽  
Complex Modal Analysis ◽  
Complex Modal

Coupled Belt-Pulley Vibration in Serpentine Drives With Belt Bending Stiffness

2004 ◽  
Vol 71 (1) ◽  
pp. 109-119 ◽  
Author(s):  
Lingyuan Kong ◽  
Robert G. Parker
Keyword(s):  
Eigenvalue Problems ◽  
String Model ◽  
Bending Stiffness ◽  
Vibration Modes ◽  
Discrete Eigenvalue ◽  
Belt Drives ◽  
Design Variables ◽  
Moving Beam ◽  
Serpentine Belt ◽  
String Models

A method is developed to evaluate the natural frequencies and vibration modes of serpentine belt drives where the belt is modeled as a moving beam with bending stiffness. Inclusion of bending stiffness leads to belt-pulley coupling not captured in moving string models. New dynamic characteristics of the system induced by belt bending stiffness are investigated. The belt-pulley coupling is studied through the evolution of the vibration modes. When the belt-pulley coupling is strong, the dynamic behavior of the system is quite different from that of the string model where there is no such coupling. The effects of major design variables on the system are discussed. The spatial discretization can be used to solve other hybrid continuous/discrete eigenvalue problems.

Design and Analysis of Automotive Serpentine Belt Drive Systems for Steady State Performance

1997 ◽  
Vol 119 (2) ◽  
pp. 162-168 ◽  
Author(s):  
R. S. Beikmann ◽  
N. C. Perkins ◽  
A. G. Ulsoy
Keyword(s):  
Steady State ◽  
Closed Form ◽  
Closed Form Solution ◽  
Form Solution ◽  
Design Parameters ◽  
Belt Drive ◽  
Automotive Engine ◽  
Theoretical Predictions ◽  
Serpentine Belt ◽  
Drive Systems

Serpentine belt drive systems with spring-loaded tensioners are now widely used in automotive engine accessory drive design. The steady state tension in each belt span is a major factor affecting belt slip and vibration. These tensions are determined by the accessory loads, the accessory drive geometry, and the tensioner properties. This paper focuses on the design parameters that determine how effectively the tensioner maintains a constant tractive belt tension, despite belt stretch due to accessory loads and belt speed. A nonlinear model predicting the operating state of the belt/tensioner system is derived, and solved using (1) numerical, and (2) approximate, closed-form methods. Inspection of the closed-form solution reveals a single design parameter, referred to as the “tensioner constant,” that measures the effectiveness of the tensioner. Tension measurements on an experimental drive system confirm the theoretical predictions.

Experimental/Numerical Analysis of the Timing Belt Drive Behavior of a V6 Engine

2003 ◽  
Author(s):  
Lionel Manin ◽  
Didier Remond ◽  
Jean-Philippe Gaborel
Keyword(s):  
Rotation Speed ◽  
Transmission Error ◽  
Strain Gauges ◽  
Belt Drive ◽  
Automotive Engine ◽  
Transmission Errors ◽  
Belt Drives ◽  
Harmonic Content ◽  
Timing Belt ◽  
The Time Domain

The timing belts used for automotive engine are asked to last more and more, and to be less noisy. In this way, it is necessary to simulate the behavior of the engine timing belt drives for optimization, but also to understand it from experimental analysis. The first objective of the work was to analyze experimentally the behavior of a V6 engine timing belt drive in terms of: pulley speeds, belt span tensions, transmission error. The second objective was to compare the measurements with simulations. The engine has four overhead camshafts and 4 valves per cylinder. The timing belt drive is composed of six pulleys, three idlers and an automatic tensioner. The crankshaft and the two first camshaft speeds are measured with optical encoders. Spans tensions are measured by means of strain gauges glued on the idler mounting axes. All the data are simultaneously recorded. Tests have been run from 800 rpm to 6000 rpm. Measured data are first analyzed in the time domain. Some phenomena like, nil span tensions, speeds acyclism and transmission error amplitude, are observed. Then, analyses of the harmonic content of the span tensions, pulley speeds and transmission errors between the crankshaft and the camshafts, are performed versus engine rotation speed. Finally, the tests have been simulated and comparisons are made between numerical and experimental results.

Modeling and Validation of Rotational Vibration Responses for Accessory Drive System—Part II: Simulations and Analyses

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Wen-Bin Shangguan ◽  
Xiang-Kun Zeng
Keyword(s):  
Excitation Frequency ◽  
General Purpose ◽  
Drive System ◽  
Dynamic Tension ◽  
Serpentine Belt ◽  
Rotational Vibration ◽  
Vibration Responses ◽  
System Part ◽  
Stiffness And Damping ◽  
General Purpose Software

This is the second part of the paper for modeling and validation of the rotational vibration responses for an accessory drive system. The unified formulas for modeling the rotational vibration of an accessory drive system are presented. In the modeling of an accessory drive system, the damping and stiffness of a belt are regarded as the function of the excitation frequency of an engine and the amplitude of belt stretching. Additionally, the creeping effect of a belt on the pulley wrap arc is included in the model. A general purpose software for calculating the rotational vibration of an accessory drive system is developed, based on the presented unified formulas. One accessory drive system with seven pulleys, a tensioner, and a serpentine belt is used as a studying example to demonstrate the unified formulas and the procedure for obtaining the rotational vibration. In the simulation of the accessory drive system, the stiffness and damping of the belt, the friction coefficient between the belt and pulley, and the excitation torques with multifrequency components from the crankshaft torsional vibration are obtained from the experiment in the first part of this paper. The static tension and steady-state tension of each belt span, along with the natural frequency of the accessory drive system, rotational vibrations of the driven pulley and tensioner arm, and the dynamic tension of the belt span are calculated and compared well with the experimental data, which validate the presented unified formulas and the developed general purpose software. The modeling method and the procedure described in this paper are instructive for designing an accessory drive system.

Rotational Response and Slip Prediction of Serpentine Belt Drive Systems

1994 ◽  
Vol 116 (1) ◽  
pp. 71-78 ◽  
Author(s):  
S.-J. Hwang ◽  
N. C. Perkins ◽  
A. G. Ulsoy ◽  
R. J. Meckstroth
Keyword(s):  
Numerical Solutions ◽  
Equations Of Motion ◽  
Operating Conditions ◽  
Equilibrium Analysis ◽  
Belt Drive ◽  
Theoretical Predictions ◽  
Serpentine Belt ◽  
Drive Systems ◽  
Nonlinear Equations Of Motion ◽  
Rotational Response

A nonlinear model is developed which describes the rotational response of automotive serpentine belt drive systems. Serpentine drives utilize a single (long) belt to drive all engine accessories from the crankshaft. An equilibrium analysis leads to a closed-form procedure for determining steady-state tensions in each belt span. The equations of motion are linearized about the equilibrium state and rotational mode vibration characteristics are determined from the eigenvalue problem governing free response. Numerical solutions of the nonlinear equations of motion indicate that, under certain engine operating conditions, the dynamic tension fluctuations may be sufficient to cause the belt to slip on particular accessory pulleys. Experimental measurements of dynamic response are in good agreement with theoretical results and confirm theoretical predictions of system vibration, tension fluctuations, and slip.

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