International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 7, July 2014)
Improvement of Stiffness Coefficient of a Passenger Car PreDamper Clutch’s Spring by Utilizing Multi-Body Dynamic
Method
Hamid-Reza Khodami1, Alireza Arghavan2, Kazem Reza Kashyzadeh3
Department of Mechanical Engineering, Semnan branch, Islamic Azad University, Semnan-Iran
As a simple viewpoint of clutch and its performance can
be expressed: it’s a tool for transferring rotary motion from
a shaft to other parts which can be used in driveline
systems.
Firstly in driveline systems, to use generated powers and
forces of engine in the other shapes or places is needed to
be transferred, so, one of the simplest ways is use of a
clutch to control this force transfer which can stop anytime
that is needed. Therefore, clutch plays an important role in
damping or transferring the noise or vibration of gearbox or
engine, hence, the study of clutch performance under
different conditions is necessary.
During Years, So Many researchers have studied
vibrations and noises of engine, gearbox and force transfer
by clutch. Also millions of dollars spent to experiment and
research to find out how to reduce this kind of vibrations,
noises and its damping or transforming by clutch and so
many improvements is applied from the beginning up to
now.
In the present paper, there’s a special attention to
vibrational application of the clutch and initial impacts of
engine at starting up. For better understanding of top issue
is presented a brief description about evolutional steps of
clutch’s improvements by other scholars.
C. L. Gaillard and his cooperators accomplished
dynamical analysis of vehicle’s clutch damper and the
dependence of dynamical parameters to frequency and
excitation amplitude that a 4 DOF model has been
suggested for clutch, gearbox and flywheel. Also
introduced different friction models such as: coulomb,
Maxwell, and Voight and finally presented some ideas for
improving them [1].
N. TSUJIUCHI and his cooperators in mechanical
department of Doshisha University and Exedy Corporation
studied about the effect of clutch dampers on driveline’s
rattle in idle state. Also made a useful analytical model to
show actual application of a clutch damper and at last
noticed that despite conditions with a high damping
performance, analysis confirms the domain of the
hysteresis torque that generates the gearbox rattle noise [2].
Abstract— in the present paper, main purpose is to
improve passenger car pre damper clutch spring’s stiffness
coefficient in order to gain more performance under
dynamical and vibrational analysis in engine at idle working.
So, to achieve this purpose, an angular velocity that is related
to the engine idle working which estimated 850 rpm and
completely sinusoidal as input to clutch system and output
angular velocity of input shaft to gearbox is assumed as
output of MSC.ADAMS software to analyze system with
various parameters. For this order, results as angular velocity
and acceleration versus time for input shaft to gearbox
reported, which investigated in initial turbulences that was
from initial impacts of engine start up process and so
converge of engine vibrations observed. Furthermore,
investigated pre damper spring’s stiffness constant as an
efficient parameter in clutch operations, angular velocity and
acceleration of gearbox input shaft’s feedback, one of the
main effective parameters of driveline’s noise and vibration
studied. Finally, results have been compared to establish best
pre damper spring’s stiffness constant equal to 25 n/mm in
mounted spring under real work and environmental
conditions. Therefore, Sensitivity analysis is performed to
validation of obtained results.
Keywords— Vehicle Clutch, Pre damper clutch, Pre
damper spring’s stiffness, Dynamical and vibrational analyze,
MSC.ADAMS Software.
I. INTRODUCTION
In the recent years lots of changes was made to
automotive industry in the world which developed this
industry and one of the most important of them is clutch
industry.
Clutch system is one of the most important systems and
its proper performance got a direct effect on vehicle
performance in driveline section at automotive industry,
like: power generator (engine) and driveline system
(transmission, differential and …). So, the efficiency of the
vehicle will be reduced in case of any problem even in
minor details.
44
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 7, July 2014)
L. Li and his cooperators examined speed-dependent
amplification in ground vehicle’s drivelines during start-up
process. First a new nonlinear model of a multi-staged
clutch damper is developed and is successfully validated by
a transient experiment, then a SDOF is developed by
incorporating a multi-staged clutch damper model, and it is
used to examine the speed-dependent amplification process
during the engine start-up [3].
In the present clutch model, to prevent fault due to use of
multiple joints, some simplifies like divide clutch into five
parts which is engine, shaft, hub flange (plate2), Inertia and
pre-damper was done. This divide includes connected parts
to flywheel inclusive cover, diaphragm spring, wire rings,
pressure plate, strap plates, disc’s facings and cushions,
disc and sub plate which they are all in engine package.
The types of connections between these parts in real
clutch which is rigid, bolts and rivets that makes the
assumption of this merging and simplifying valid and close
to reality is that the reason of this simplifying and merging.
On the other sides the shaft includes: output shaft from the
disc and spline hub. Also the hub flange includes only hub
flange (plate2, hub plate). The pre-damper includes only
spline hub friction plate and finally the inertia part was
added to simulate the mass moment of inertia for all gears
and shafts of the gearbox. So, in order to measure
acceleration and deceleration, calculated their mass and
inertia [7-8].
II. MODELING AND SIMULATION
At the first step, has been provided clutch of the certain
vehicle with all its parts such as clutch’s disc, strap plates,
springs and etc. in the next step, extracted all points of
outside surfaces of different clutch parts by using CMM 3D
scanner and imported to the CATIA as a optic files, so
modeled 3D geometry of each parts in the software. Then
all geometrical parameters of clutch in SOLIDWORKS
assembled like Figure.1.
A. Loads and Constraints
In the proposed model, a quasi-sinusoidal rotational
motion similar to the motion of an eight-valve inline fourcylinder in an idle state (Figure.2) applied as input data to
software [4].
In the following, described the used constrains to
simulate proposed model that:
- Engine: Because of the constraints that are bolts, rivets
and rigid constraints between pressure plate and facings
(Considering the idle state of the engine and a full healthy
clutch), all parts in this package merged together and
considered as a part, so that whole package of engine got
1DOF and it’s a rotation around its center axis.
-Hub flange: This plate which also called plate2 or hub
plate is one that connects the engine package to the predamper and shaft packages with constraints and forces. At
the first step, it connects to the engine by a revolute joint
which has got 1DOF that is a rotation around the center
axis of the engine. The next step, it connects to helical
springs and pre-damper springs which assumed as forces in
MSC.ADAMS software. The other side of spring forces is
spline hub friction plate for pre-damper springs and engine
for helical springs.
-Shaft: This part inclusive output shaft from the clutch
disc and spline hub that merged together.
Constraint which used for this package is a revolute joint
that has been explained above and fixed joint that removes
completely all DOF(s) and bind the body up to another
body which attached there.
Fig.1 Geometrical model and assemble of clutch
Some simplifying on model has done to clutch modeling
process such as necessary changes and merges (a little
deformation which made to cushions in the process of
assembly that transform their shape from sinusoidal to
almost flat shape at last). The spring of the clutch disc was
not available to model at the modeling software because
occurs their deformation in the assembly process, so, this
parts are so effective on analysis results. Therefore, use of
spring parameters is necessary.
45
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 7, July 2014)
Table-2
Characteristic of the used material in the present clutch’s model [9]
So, this package is fixed to spline hub friction plate. The
Revolute joint is with engine that let shaft package rotates
freely into the engine. Another limitation which applied to
this package is contact force that applied between this
package and Hub flange to prevent geometrical interference
during simulation and if any contact occurred between two
bodies there, the force of the contact can be measured and
also the reaction of this contact is adjustable due to
requested parameters.
-Spline hub friction plate: This package is the seat of
pre-damper springs. It’s fixed to shaft package, therefore
has got same action of shaft package.
-Inertia: As explained above, this package brought up in
proposed model to accurately effect the mass moments of
inertia and the mass of the gearbox. And its shaft while
engine working in idle state in the vibration of the clutch
[5-6].
Part name
Used materials
Clutch cover
St12,St13,Stw22,Stw24
Wire rings
CK30-60
Diaphragm spring
50CrV4
Strap plates
CK75,Ck85
Pressure plate
CG25,CG30
Facings
Ray Bestos: B8805, B1675
Cushions
CK75,CK85
Plates of disc
St12,St13
Clutch springs
TDSiCr,67SiCr5
Friction plates
PA6.6
Spline hub
Powder Metallurgy
Fig.2 a quasi-sinusoidal rotational motion of an eight-valve inline
four-cylinder [4]
Table.1
information of used springs in the present clutch’s model [9]
Type of
Spring
Pre
Load
(N)
Initial
Length
(mm)
Damping
Coefficient
(N.S/mm)
Stiffness
Coefficient
(N/mm)
Length
at pre
Load
(mm)
III. DISCUSSION AND RESULTS
Helical
Springs
900
40.5
0.1
205
36.4
Pre
Damper
Springs
70
14
0.1
14.11
9.3
In this section the reactions of clutch’s springs and
dampers to the applied harmonic vibration has been
studied. As mentioned above, the applied excitation to the
clutch system is quasi-sinusoidal and has been loaded on
engine package. The reaction that is mentioned derives
from the performance and characteristics of pre damper
springs and helical springs, But in the present research
focused on the performance and characteristics of pre
damper springs.
46
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 7, July 2014)
The applied excitation that comes from engine transfers
to shaft, hub flange, and inertia and spline hub by helical
and pre damper springs. It means that all these parts are
rotating by the engine package. Thus, the engine forces and
vibrations are transferred to the hub flange by helical
springs, and the hub flange’s forces and vibrations also
transferred to the output shaft by pre damper springs.
Therefore, the shaft, spline hub and inertia packages have
approximately similar vibrations because of the constraints
used between them.
At first, deformations of pre damper springs has been
measured and shown below (Figure.3 and 4). Because of
the impact of the engine startup these vibrations have got a
difference at startup that called here initial turbulences.
Also it has been observed that the vibrations are regular at
the rest after initial turbulences. It’s noticeable that the step
of the solver has been set to 10000 times during 5seconds
which was acquired with several tests to achieve the best,
accurate and safe answer.
For all of the vibration diagrams are regular as shown in
Figure.4 after initial turbulences, so now, discussed about it
in all part of this research.
You can see (Figure.5) deformation diagram of the pre
damper spring in term of a time and its reaction to the
engine vibration.
Fig.5 Compared diagram of the deformation of the pre damper
springs at initial turbulences
In order to study the effect of existence or nonexistence
of the pre damper springs on the clutch’s first vibration at
initial turbulences, analyzed at software and obtained
results shown in Figure.6
Fig.3 Compared diagram of the applied force to pre damper springs
at initial turbulences
Fig.6 Effect of the existence or nonexistence of the pre damper springs
at inital turbulences on clutch’s vibraion by output shaft's angular
velocity
The output shaft angular velocity fluctuation for a clutch
with pre damper is much better than a clutch without pre
damper and the diagram shape is smoother also. Therefore,
the clutch’s vibration for the one that has pre damper spring
is much better.
One of the most important effective parameters in
angular velocity fluctuation and vibrations of the clutch
system are stiffness coefficient of pre damper that studied
it. So, in the following, the sensitivity analysis of the
variation of stiffness coefficient brought up in Figure.7.
Fig.4 Compared diagram of the applied force to pre damper springs
after initial turbulences
As it’s seen above, the diagram of the applied force to
the pre damper springs for both of these springs are almost
similar together. And has been observed that in initial
turbulences of the engine rotation start up, the impact
damped well by pre damper springs and just after a few
seconds the vibrational behavior of the clutch returned to
the normal and regular mode.
47
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 7, July 2014)
3. By optimal increasing of pre damper springs stiffness
coefficient better results has been gained in the area of
25 n/mm for this parameter. Therefore it’s possible to
increasing the stiffness coefficient of the pre damper
springs up to an optimal value in order to decrease
initial impacts and turbulences during engine start up
process or another accelerate or decelerate of the
engine, and finally improve the transfer to the
gearbox.
4. With increasing the frequency of the engine
vibrations, it has been observed that the frequency of
the vibrations of the output parts like output shaft has
been increased either, therefore the angular
acceleration peaks has been changed and increased
which is not desirable for driveline system that
connected to the continue of this kinematic and
kinetic chain. So by decreasing the frequency and
amplitude of the engine vibrations, improvements of
the gearbox and driveline are reachable.
Fig.7 Sensitivity analysis of the output shaft's angular velocity to
stiffness coefficient of pre damper springs at initial turbulences
IV. CONCLUSION
Provide real test and doing dynamic and vibration tests
of Automobile’s clutch are very costly. Hence, Using
virtual environments and test simulations to decrease
results time is most important in industrial design. So,
several different stiffness coefficients has been analyzed
and tested. Finally, reported optimum and best amount of
pre damper spring’s coefficient in according to angular
velocity fluctuations and vibrations of the clutch system
which is 25 Newton per millimeter. And some result of this
research listed such as:
1. Improvements of vibration conditions, including the
value of angular velocity changes at sudden impacts
and changes and as a result smother transform of this
impacts to the gearbox for pre damper clutches and
converging vibrations after initial turbulences.
Therefore after impacts and initial turbulences, which
is the results of engine start up or another
accelerations, pre damper springs completely
transform regular vibrations of the engine and don’t
make observable changes after initial turbulences.
2. Improvement of conditions in angular velocity and
acceleration peaks (at impacts of initial turbulences)
with optimal increase of damping coefficient of pre
damper springs. Although this changes has been
measured in very small area, but the sensitivity of
angular velocity of output shaft to this parameter has
been observed.
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
48
C. L. Gaillard, R. Singh, “Dynamic analysis of automotive
clutch dampers”, Applied Acoustics, Vol60, 2000.
N. Tsujiuchi, T. Koizumi, N. Hara, Y. Yamakaji, K.
Yamashita,“The effects of clutch damper in idling driveline
rattle”, EXEDY Corporation, Department of Mechanical
Engineering, Doshisha University, 2012.
L. Li, R. Singh, “Analysis of speed dependent vibration
amplification in a nonlinear driveline system using Hilbert
transform”, SAE, 2013.
R. Shaver, “Manual transmission clutch systems-AE17, SAE,
1997.
R. N. Jazar, “Vehicle Dynamics: Theory and Application”,
springer, 2008.
T. D. Gillespie, “Fundamentals of vehicle dynamics”, SAE,
2002.
Getting Started Using ADAMS/View, MSC software
publication, 2008.
Building Models in ADAMS/View, Mechanical Dynamics,
Incorporated, Printed in the United States of America, 2000.
Clutch information notebook, Shayan Sanat Company, Clutch
and Automotive Industry, Tehran, Iran, 2009.