August 23-26, 2010, Kyoto, Japan
Dynamic Simulation and Analysis of Automotive Engine’s
Timing Silent Chain System
Dong Chengguo
College of Mechanical Science and
Engineering Jilin University
Changchun, Jilin, 130025, China Email: dongcg07@mails.jlu.edu.cn
Meng Fanzhong
Institute of chain transmission
Jilin University
Changchun, Jilin, 130025, China
Email:fzm75@tom.com
Feng Zengming(Corresponding Author)
Cheng Yabing Zhang Lei
College of Mechanical Science and
Engineering Jilin University
Changchun, Jilin, 130025, China Email: fengzm@jlu.edu.cn
With the improvement of the speed and load of the automotive engine, and silent chain technology, as silent chain has a compact structure, high transmitting efficiency, high reliability and high wear resistance, its vibration and noise is low, and the silent chain have the advantage of life-long maintenance-free, it significant overcomes the gear drive and belt drive performance, therefore, the silent chain is increasingly widely used in automotive engine timing system.
Based on the analysis of the new silent chain with inner-outer compound meshing mechanism, and based on the combination of multi-body dynamics theory and modern contact dynamics theory, using the multi-body dynamics software RecurDyn, the paper establishes the timing silent chain system simulation model. Under the condition of variable speed and variable load at high speed, the multi-body dynamics model of engine timing silent chain system has been simulated. By analyzing the working path of the silent chain under the different speed and load operating conditions, the paper studied the dynamic response of the timing silent chain system and obtains the tensioning force curve of plate, pin, sprocket, damping plate, board and tensioner throughout the operating cycle of the timing silent chain system. After analysis and comparison of the calculated results, the multi-body dynamics model of the engine timing silent chain system is verified to be reasonable. The research result has important practical significance for reducing the development and production cycle of physical prototypes.
Copyright (c) 2010 by JSME
5th Asian Conference on Multibody Dynamics 2010
August 23-26, 2010, Kyoto, Japan
Dynamic Simulation and Analysis of Automotive Engine’s Timing Silent Chain System
Dong Chengguo
College of Mechanical Science and Engineering
Jilin University
Changchun, Jilin, 130025, China Email: dongcg07@mails.jlu.edu.cn
Feng Zengming (Corresponding Author)
Cheng Yabing Zhang Lei
College of Mechanical Science and Engineering
Jilin University
Changchun, Jilin, 130025, China Email: fengzm@jlu.edu.cn
ABSTRACT
With the improvement of the speed and load of the automotive engine, and silent chain technology, as silent chain has a compact structure, high transmitting efficiency, high reliability and high wear resistance, its vibration and noise is low, and the silent chain have the advantage of life-long maintenance-free, it significant overcomes the gear drive and belt drive performance, therefore, the silent chain is increasingly widely used in automotive engine timing system.
Based on the analysis of the new silent chain with inner-outer compound meshing mechanism, and based on the combination of multi-body dynamics theory and modern contact dynamics theory, using the multi-body dynamics software RecurDyn, the paper establishes the timing silent chain system simulation model. Under the condition of variable speed and variable load at high speed, the multi-body dynamics model of engine timing silent chain system has been simulated. By analyzing the working path of the silent chain under the different speed and load operating conditions, the paper studied the dynamic response of the timing silent chain system and obtains the tensioning force curve of plate, pin, sprocket, damping plate, board and tensioner throughout the operating cycle of the timing silent chain system. After analysis and comparison of the calculated results, the multi-body dynamics model of the engine timing silent chain system is verified to be reasonable. The research result has important practical significance for reducing the development and production cycle of physical prototypes.
1. Introduction
Due to the noise and life requirements, chain drive is more and more widely used in modern autos as timing
Meng Fanzhong
Institute of chain transmission
Jilin University
Changchun, Jilin, 130025, China
Email:fzm75@tom.com
drive system. Chain drive is non-conjugated meshing drive with a flexible part in the middle. The polygon effect makes the pitch line of the chain and the pitch circle of the sprocket intercrossing and tangent alternately. Position of the chain’s center line varies cyclically, which makes the linear velocity of the silent chain and the angular velocity of the sprocket varying cyclically, and then it seriously effects the accuracy of the valve drive (timing drive).
Nowadays, more studies of the timing drive system are roller chain and bushing chain. The study of the silent chain just centers on the meshing mechanism and analysis of the shock characteristic, but the study of the chain which works at a high speed is few. This text use multi-body dynamics theory and modern dynamics contact theory to research the dynamic characteristics of the automotive engine’s timing silent chain at different speeds.
2. Contact dynamic theory of automotive
silent chain
In the automotive timing drive, as the polygon effect and alternate load, the number of silent chain’s meshing factor is large, and the meshing impact force is complex. In the field of multi-body dynamics, one of the most popular approximations of the dynamic behavior of a contact pair has been that one body penetrates into the other body with a velocity on a contact point.
In the contact force model, the contact normal force can be defined as the function of the penetration of the node into the patch. When there is penetration on the contacted surface, the contact normal force is obtained by:
（1）
Where δ and are an amount of penetration and its
Copyright (c) 2010 by JSME
velocity, respectively. The k and c are the spring and damping coefficients, which are determined by an experimental method. The exponents m1, m2 and m3 are spring coefficient, damping coefficient and invading coefficient. The exponent m1 and m2 generates a non-linear contact force and the exponent m3 yields an indentation damping effect.
The friction force and the contact tangential force are obtained by:
（3） Where fn，ff，fmax, are contact force’s normal force,
tangential force and maximum force, respectively. μ(v) is
friction coefficient, and the friction coefficient is divided
into dynamic friction coefficient μd and static friction
coefficient μs.
When the relative speed between two contacted bodies
is below the static friction critical velocity, the friction
coefficient is obtained by:
(5)
When the relative speed between two contacted bodies
is above the dynamic friction critical velocity, the friction coefficient is μd.
The curve between the friction coefficient and the relative speed is shown in fig.1.
Fig.1 CURVE BETWEEN THE FRICTION COEFFICIENT AND THE RELATIVE SPEED
5th Asian Conference on Multibody Dynamics 2010
August 23-26, 2010, Kyoto, Japan
3. Building of dummy model of the auto
engine timing chain
The timing chain system in the research is based on the four-cylinder, 16-valve, and double-camshaft top set gasoline engine (DOHC). As is shown in fig.2, the timing chain system of the engine consist of a crankshaft sprocket (drive sprocket), two camshaft sprockets (intake camshaft sprocket and exhaust camshaft sprocket), guiding plates (damping plate), tension plates, tensioner, chain plates, guide plates and pins. In order to have a better understanding of the process of chain drive, this text divided a cycle of the chain into six steps: Crankshaft
Sprocket (CS), Slack Span (SSP), Exhaust Camshaft
Sprocket (ECS), Camshaft Span (CSP), Intake Camshaft Sprocket (ICS) and Tight Span (TCP). RD/Timing Chain Toolkit is a professional module based on RecurDyn for simulation of timing chain system; there are all the components, constraints and external loads of the timing chain system in this module. The finished automotive engine timing chain system model is shown in fig.2. In this model, there are hinge constraints between Crankshaft Sprocket and crankcase (Ground) and between Camshaft and crankcase. There is a driver on Crankshaft Sprocket’s hinge constraint. This model use a internal meshing silent chain with 8 mm pitch, teeth number of the crankshaft sprocket is z1=19, teeth of intake camshaft sprocket and exhaust camshaft sprocket are z2=z3=38, the length of the chain is 134 links. There are contact constraints between the chain plate and the sprocket,
guiding plate tension plate, and so as to the tensioner and
the tension plate. There is bushing hinge constraint between chain plate and pins. Fig.2 MODEL OF THE TIMING SILENT CHAIN SYSTEM
Copyright (c) 2010 by JSME
4. Simulation and result
Make a simulation of the built multi-body dynamics model which has contact meshing. The simulation is about the dynamic characteristics of the timing silent chain in six different conditions that the engine’s speed ranges from 1000rpm to 6500rpm. And the idle speed of the engine is 1000rpm; the speed when the engine has a maximum output torque is 4000rpm, the speed when the engine has a maximum output power is 6500rpm. The result is below.
4.1 Trace of the links
The traces in fig.3 are traces in a cycle when the speeds are 1000rpm, 4000rpm and 6500rpm, respectively. Trace of the links in x-y plane matches the due trace. In the SCP step, because of the low speed of the links, many undulant parts occur on the curve, they are caused by the polygon effect. While at a high speed, because of the high speed, undulant effect is relatively slight; but in the steps when the guiding plate connects the crankshaft sprocket and when the crankshaft sprocket connects the tension plate, because of the rapid shock vibration of the crankshaft sprocket and the polygon effect of the chain’s own, fluctuation in local area is serious.
a) 1000rpm b) 4000rpm c) 6500rpm
Fig.3 TRACE OF THE LINKS
4.2 Simulation of the tensile force of the links Chain drive is made up of links by hinge constraints, and it is non-conjugated meshing drive with a flexible part in the middle. The links are the main part to transfer the power in the chain drive. The tensile force and its changes reflect the force of the chain drive when working. The curves of the tensile force of the links reflect the chain’s start-up impact, change of the tensile forces of the slack span and the tight span, approach impact and the dynamic load caused by the polygon effect.
5th Asian Conference on Multibody Dynamics 2010
August 23-26, 2010, Kyoto, Japan
N)3000e(2500CSSSPECSCSPICSTSPcro2000F150010005000017595612251509173225393000a)1000rpm Crankshaft Angle(deg)3000N)e(2500CSSSPECSCSPICSTSPcro2000F150010005000017595612251509173225393000b)2000rpm Crankshaft Angle(deg)3000N)e(2500CSSSPECSCSPICSTSPcro2000F150010005000017595612251509173225393000c)3000rpm Crankshaft Angle(deg)
3000N)e(2500CSSSPECSCSPICSTSPcor2000F150010005000017595612251509173225393000d)4000rpm Crankshaft Angle(deg)3000N)(e2500CSSSPECSCSPICSTSPcro2000F150010005000017595612251509173225393000e)5000rpm Crankshaft Angle(deg)3000N)(2500CSSSPECSCSPICSTSPecro2000F150010005000017595612251509173225393000f)6500rpm Crankshaft Angle(deg)
Fig.4 CURVE OF THE FORCE OF LINKS
The forces of the links when the crankshaft sprocket is at different speeds range from 1000rpm to 6500rpm are shown in fig.4. At the step of CS, the forces at different speeds basically hold on 1400N, but at the steps of ECS and ICS, the forces hold on 1000N, this is because that the links are affected by the effective peripheral force of the drive sprocket at the localizing step. At the SSP step, the trend of the forces is that they descend after the links mesh out of the crankshaft sprocket until the links mesh in the exhaust camshaft sprocket; and the forces of the links increase slowly from meshing out of the intake camshaft
Copyright (c) 2010 by JSME
sprocket to meshing into the crankshaft sprocket, while the forces of the chain plate increase with the speed, and the fluctuation is serious. The frequency domain after FFT-change is shown in fig.5.
900800700600)N(e500croF4003002006500100400050003000Engine Speed010002000 (rpm)02468101930405060Engine Order(NO.)
Fig.5 FFT ANALYSIS OF THE FORCES OF LINKS
As is shown in fig.5, peaks of the tensile force of the links appear at low harmonic orders 2th, 4th, 6th, 8th and 10th. The tensile force increases from 100N when the speed is 1000rpm to 600N when the speed is 5000N, and then decreases to 500N when the speed is 6500rpm. The peak at harmonic order 1th is relatively high; this is caused by the inertial load of the timing system. It can be known from the harmonic order of the auto that the polygon order (19th) is not so evident, but it becomes evident at high speed.
4.3 Analysis of the transmission ratio of the
crankshaft sprocket and the camshaft sprocket
2 1.9991.9981.9971.9961.9951.994Intake CamsprocketExhaust Camsprocket1.9931.9921.9910 50010001500200025003000
Crankshaft Angle(deg)
a) 1000rpm
2oita1.9995R n1.999ois1.9985sim1.998sna1.9975rT1.9971.9965Intake CamsprocketExhaust Camsprocket1.9961.99550 50010001500200025003000Crankshaft Angle(deg)
b) 2000rpm
5th Asian Conference on Multibody Dynamics 2010
August 23-26, 2010, Kyoto, Japan
2 oi1.9995taR 1.999nois1.9985sim1.998snar1.9975TIntake Camsprocket1.997Exhaust Camsprocket1.99650 50010001500Crankshaft Angle 20002500(deg)
3000
c) 3000rpm
2 oitaR 1.9995noiss1.999imsna1.9985rT1.998Intake CamsprocketExhaust Camsproket1.99750 500100015002000Crankshaft Angle(deg)
25003000
d) 4000rpm
oitaR2.001 no2issim1.999sna1.998rT1.9971.996Intake CamsprocketExhaust Camsprocket1.9950 500100015002000Crankshaft Angle 2500(deg) 3000
e) 5000rpm
2.001 oita2.0005R no2issim1.9995sna1.999rT1.99851.998Intake CamsprocketExhaust Camsprocket1.99750 50010001500200025003000
f) 6500rpm
Crankshaft Angle (deg)
Fig.6 TRANSMISSION RATIO OF CRANKSHAFT SPROCKET
AND CAMSHAFT SPROCKET
The transmission ratios of the crankshaft sprocket and the camshaft sprocket under different speeds are shown in fig.6. When the speed is low, the transmission ratio of the intake camshaft sprocket is a little bigger than the exhaust camshaft sprocket, the fluctuation trend is alike. But with the increase of the speed, the margin between the transmission ratios of the intake and exhaust camshaft
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Transmission Ratio
sprockets, when the speed is higher than 5000rpm, the transmission ratios are the same.
4.4 Analysis of normal contact force between
the tensioner’s piston and the tension plate
)N1000( ecr800oF tca600tnoC4002000050010001500200025003000Crankshaft Angle (deg)
a) 1000rpm
)N1000( ecr800oF tca600tnoC4002000050010001500200025003000
b) 2000rpm
Crankshaft Angle(deg)
)N1200( ec1000roF 800tcatn600oC4002000050010001500Crankshaft Angle 20002500(deg)
3000
c) 3000rpm
)N1000 ecro800F tca600tnoC4002000050010001500Crankshaft Angle 20002500(deg)
3000 d) 4000rpm
5th Asian Conference on Multibody Dynamics 2010
August 23-26, 2010, Kyoto, Japan
)2000N( ecr1500oF tcatn1000oC5000050010001500200025003000
e) 5000rpm
Crankshaft Angle(deg)
2000)N( ecr1500oF tcat1000noC5000050010001500200025003000
f) 6500rpm
Crankshaft Angle(deg)
Fig.7 NORMAL CONTACT FORCE BETWEEN THE TENSIONER’S PISTON AND THE TENSION PLATE
The tensioner is an important part of the timing chain drive system. The normal contact force between the tensioner’s piston and the tension plate is a key target. As is shown in fig.7, the contact force ranges from 250N to 560N at the speed of 1000rpm, with the increase of speed, the fluctuation valuation and the fluctuation scope increase correspondingly similarly, at the speed of 5000rpm, the scope reach to 0~1100N, and at the speed of 6500rpm, when there is the maximum output power, the scope is 0~700N. Normal contact forces between the tensioner’s piston and the tension plate are shown in fig.7.
600)N(ecr500Fo40030020065001005000300040002000Engine Speed01000 (rpm)02468101519253035404550Engine Order(NO.)
Fig.8 FFT ANALYSIS OF THE CONTACT FORCE BETWEEN THE
TENSIONER’S PISTON AND THE TENSION PLATE
Peaks of the normal contact force appear at low harmonic orders 2th, 4th, 6th, 8th and 10th. Among which the 2th
harmonic order appears to be the same trend. The contact force increases from 140N when the speed is 1000rpm to 480N when
Copyright (c) 2010 by JSME
5th Asian Conference on Multibody Dynamics 2010
August 23-26, 2010, Kyoto, Japan
the speed is 500N, and then it decreases to 350N when the speed is 6500rpm. Peak of the normal contact force between the
tensioner’s piston and the tension plate is relatively low at low harmonic orders 2th, 4th, 6th, 8th 10th and polygon order (19th), while it turn out to be relatively high at a high speed.
5 CONCLUSION
1. Through the analysis of the trace of links ，the trace
C. Weber, W. Herrmann and J. Stadtmann. Experimental Investigation Into the Dynamic Engine Timing Chain Behaviour. SAE paper 980840
Pang Jian, Chen Gang, He Hua. Noise and Vibration of Auto - Principle and Application. Beijing Institute of Technology Press, 2006
Jesus Rodriguez, Rifat Keribar and Greg Fialek. A Comprehensive Drive Chain Model Applicable to Valvetrain Systems. SAE 2005-01-1650. of the simulation shows a good correlation with experimental data；
2. Tensile force of links at different speeds and normal
contact force between tensioner and tension plate are analyzed. We obtain the dynamic amplitude at different speeds and different engine order of tensile force and normal contact force through FFT change; 3. The following conclusion obtained through the
analysis of transmission ratio between crankshaft sprocket and camshaft at different speeds. At a low speed, the transmission ratio of intake camshaft is larger than the transmission ratio of exhaust camshaft, and there is a certain gap of transmission phase. At a high speed, the transmission ratio of intake camshaft and exhaust camshaft maintain at 1.997~2.001, driving accuracy, the gap is very small.
ACKNOWLEDGMENT
This work was supported by a grant from the National Natural Science Foundation of China (General Program, No.50275062).
REFERENCES
RecurDyn/Solver Theoretical Manual, 2009. Function Bay, Inc.
User’s Manual for Timing Chain, 2009. Function Bay, Inc.
Meng Fanzhong. Meshing mechanism of silent chain. Machinery Industry Press，2009
FENG Zengming. Meshing mechanism and dynamic analysis of new silent chain. Changchun: Jilin University, College of Mechanical Science and Engineering, 2006.
Chintien Huang ,Kuen-Chuan Lin, Leo Kosasih. Kinematic Analysis of Chordal Action and Transmission Errors of Silent Chains, SAE paper 2006-01-0619.
Hiroshi Takagishi, Kazuaki Shimoyama, Masaru Asari. Prediction of Camshaft Torque and Timing Chain Load for Turbo Direct Injection Diesel Engine. SAE paper 2004-01-0611.
Martin Sopouch, Wolfgang Hellinger, Hans H. Priebsch. Simulation of Engine’s Structure Borne Noise Excitation Due to the Timing Chain Drive. SAE paper 2002-01-0451
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