DOHC A Study on the Nonlinear Dynamic Characteristics of DOHC Engine Valve Train System 2000
DOHC (A Study on the Nonlinear Dynamic Characteristics of DOHC Engine Valve Train System) 200012 2000
. 200012
..... i Nomenclature..... iv List of figures.....vi List of tables......viii I.......... 1 Surging Quarter Bridge i
3.1 14 3.2 18 3.3 References Abstract... ii
DOHC(Double Over Head Camshaft) (surging) (strain gage) (preload). (washer) (accelerometer) (LVDT) (node) rpm (cam) (tappet) (valve) spring) (component) (ValDyn) (cam profile) iii
Nomenclature y : the axial deflection for one complete turn, m n a : number of active coils ρ : density of spring material, 3 kg / m δ : total axial deflection, m α : wave velocity, 2 m / s C : equivalent damping coefficient of valve spring, N s / m eq E : Young s modulus of valve spring, Pa G. F : gage factor L : total helix length of spring, m V : ( V ) r [ V / ] [( V / V ) ] in ex strained in ex unstrained R : line resistance, Ω L R g : gage resistance, Ω R 3 : dummy resistance, Ω ' c : damping coefficient per unit length of wire, N s / mm iv
ξ : viscous damping factor ε : strain ω 1 : first natural frequency, Hz v
List of figures Fig. 2.1 Valve spring Fig. 2.2 Schematic of valve train motions Fig. 2.3 Quarter Bridge three wire connection method Fig. 2.4 Input cam lift Fig. 2.5 Schematic of Direct Attack Valve train Fig. 3.1 Schematic of Engine experimental device Fig. 3.2 Data acquisition device Fig. 3.3 Data acquisition path Fig. 3.4 Cylinder head (DOHC) Fig. 3.5 Tappet, Retainer, Valve spring, Split key, Valve guide, Intake valve, Exhaust valve Fig. 3.6 Schematic of valve spring tester Fig. 3.7 Spring constant K=35854( N / m ) Fig. 3.8 Schematic of strain gage attachment position Fig. 3.9 Schematic of washer position for preload Fig. 3.10 Schematic of accelerometer attachment position Fig. 3.11 Schematic of encoder experimental device Fig. 3.12 Schematic of LVDT attachment position Fig. 3.13 Labview program (front panel) Fig. 3.14 Labview program(block diagram) Fig. 4.1 Spring strain at static loading(1) Fig. 4.2 Spring strain at static loading(2) Fig. 4.3 Spring strain at static loading(3) Fig. 4.4 Fig. 4.5 Fig. 4.6 Spring force at 600 rpm Spring force at 800 rpm Spring force at 1000 rpm Fig. 4.7 Spring force at preload 260 N vi
Fig. 4.8 Spring force at preload 300 N Fig. 4.9 Spring force at preload 340 N Fig. 4.10 Intake valve acceleration Fig. 4.11 Exhaust valve acceleration Fig. 4.12 Cam lift and valve acceleration at 2000 rpm Fig. 4.13 Cam lift and valve acceleration at valve opening range (2000 rpm ) Fig. 4.14 Cam lift and valve acceleration at valve closing range (2000 rpm ) Fig. 4.15 Signals of encoder, valve acceleration at 800 rpm Fig. 4.16 Valve lift Fig. 4.17 Valve lift at cam maximum lift range Fig. 4.18 Valve lift at valve opening range Fig. 4.19 Valve lift at valve closing range Fig. 4.20 Valve spring force at 2000 rpm Fig. 4.21 Valve spring force at 4000 rpm Fig. 4.22 Valve spring force at 6000 rpm Fig. 4.23 Valve spring force at viscous damping Fig. 4.24 Valve spring force Fig. 4.25 Cam & tappet contact force Fig. 4.26 Valve seat force Fig. 4.27 Valve lift Fig. 4.28 Valve acceleration Fig. 4.29 Valve velocity Fig. 4.30 Valve velocity at valve closing range Fig. 4.31 Valve acceleration(ricardo software & experiment) Fig. 4.32 Valve lift(ricardo software & experiment) Fig. 4.33 Valve spring force(ricardo software & numerical method vii
List of tables Table 2.1 Input cam lift Table 2.2 Ricardo input data for each parameters Table 3.1 Experimental device specification Table 3.2 The role of experimental device Table 3.3 Valve spring dimension Table 3.4 Valve, Tappet, Retainer mass Table 3.5 Valve spring height Table 3.6 Strain gage attachment position on valve spring(static state) viii
1 (surging) (dynamic) (component)
2 DOHC (push rod) (OHC) (ValDyn) (valve timing) (volumetric flow) (component) (motion) (displacement)
(coulomb) (viscous) m Q (inertia force) df a = 2 2 γ πd y ds 2 g 4 t Fig. 2.1 Valve spring 3
(total axial deflection) δ = n y= πdn a a y s (total force) P = kδ = kπdn y s a (net force) df 2 P y = ds = kπdn a ds s s b 2 (damping force) y t = c ' ds df d df = df df a b d 2 2 2 γ πd y ' y y + c = kπdn 2 2 g 4 t t a s 2 y t + c y = α t 2 eq 2 2 2 y s 4
5 (start motion) Fig. 2.2.1 (contact motion) Fig. 2.2.2 (jump motion) Fig. 2.2.3 (linkage) (bounce motion) Fig. 2.2.4
start motion contact jump motion bounce Fig. 2.2 Schematic of valve train motions 6
7 (surging) (wire) (residual stress) (steel) (spring stiffness)
8 (Quarter Bridge) (space) (dummy) (lead) + + = g L r r R R V GF V 1 ) 2 (1 4 ) strain(ε Fig. 2.3 Quarter bridge three wire connection method
(undamped) (viscous damping) 2 y 2 t + c eq y t = α 2 2 y 2 s c eq (natural frequency) (first natural frequency) = απ 4kπ L = Ld ρ ω 1 2 c eq (critical damping) 4kπ c eq 2ξω1 = 2ξ 2 Ld ρ = ξ.[5] (finite difference scheme) y 2 2 i, j+ 1 = p ( yi+ 1, j 2yi, j + yi 1, j ) + 2yi, j yi, j 1 t ceq i = 0,1,..., M j = 0,1,..., N 9
x = 0 y( x, t) = 0 x = L y( x, t) = -y 0 ( t ) CFL (Courant, Friedrichs, Lewy) α t 0 < p = 1 x F s y = Fe = kl x= L t x= L (cam profile)fig. 2.4 10 8 Cam Profile 6 mm 4 2 0-2 0 60 120 180 240 300 360 Cam angle (degree) Fig. 2.4 Input cam profile 10
Table 2.1 Input cam profile Lift(m) Lift(m) Lift(m) Lift(m) Lift(m) Lift(m) 0 0 25 2.9075 50 7.6140 75 8.2775 100 4.8064 125 0.1552 1 0.0003 26 3.1569 51 7.7207 76 8.2185 101 4.3589 126 0.1450 2 0.0028 27 3.4043 52 7.8206 77 8.1526 102 4.5855 127 0.1350 3 0.0078 28 3.6489 53 7.9138 78 8.0799 103 4.1271 128 0.1250 4 0.0153 29 3.8900 54 8.0030 79 8.0030 104 3.8903 129 0.1150 5 0.0250 30 4.1238 55 8.0798 80 7.9139 105 3.6499 130 0.1050 6 0.0350 31 4.3588 56 8.1526 81 7.8207 106 3.4062 131 0.0950 7 0.0450 32 4.5854 57 8.2185 82 7.7207 107 3.1600 132 0.0850 8 0.0552 33 4.8063 58 8.2775 83 7.6140 108 2.9122 133 0.0750 9 0.0706 34 5.0213 59 8.3296 84 7.5006 109 2.6636 134 0.0650 10 0.0994 35 5.2303 60 8.3747 85 7.3805 110 2.4147 135 0.0550 11 0.1482 36 5.4333 61 8.4130 86 7.2538 111 2.1665 136 0.0450 12 0.2213 37 5.6303 62 8.4443 87 7.1205 112 1.9205 137 0.0350 13 0.3207 38 5.8211 63 8.4687 88 6.9805 113 1.6796 138 0.0250 14 0.4469 39 6.0057 64 8.4861 89 6.8342 114 1.4467 139 0.0153 15 0.5990 40 6.1842 65 8.4965 90 6.6813 115 1.2254 140 0.0078 16 0.7754 41 6.3561 66 8.5000 91 6.5219 116 1.0193 141 0.0028 17 0.9730 42 6.5219 67 8.5000 92 6.3562 117 0.8317 142 0.0003 18 1.1885 43 6.6812 68 8.4965 93 6.1841 118 0.6654 143 0 19 1.4180 44 6.8341 69 8.4861 94 6.0058 119 0.5231 144 0 20 1.6578 45 6.9805 70 8.4687 95 5.8212 120 0.4052 145 0 21 1.9093 46 7.1204 71 8.4443 96 5.6304 121 0.3122 146 0 22 2.1542 47 7.2538 72 8.4130 97 5.4334 122 0.2437 147 0 23 2.4055 48 7.3805 73 8.3747 98 5.2304 123 0.1977 148 0 24 2.6568 49 7.0060 74 8.3295 99 5.0214 124 0.1702 149 0 11
(ValDyn) (Ricardo Consultant Engineering, Inc.) (ValDyn) DOHC (cam) (tappet) (valve) seat) (valve spring) DOHC Table 2.2 Fig. 2.5 Fig. 2.5 Schematic of Direct Attack Valve train 12
Table 2.2 Ricardo input data for each parameters Parameter Data cam stiffness 107.700( N / mm ) cam damping 420.30 ( N s / mm ) cam & tappet stiffness 70000( N / mm ) cam & tappet damping 355.7( N s / mm ) tappet & valve stiffness 40000( N / mm ) tappet & valve damping 52( N s / mm ) seat stiffness 105000( N / mm ) seat damping 532( N s / mm ) tappet mass(retainer ) 49.34 g valve spring mass valve mass preload spring material shear modules 38.8 g 42.04 g 260 N 79290 MPa fraction of critical damping( ξ ) 0.025 material density 3 7850( kg / m ) wire diameter 3.7125( mm ) mean coil diameter 22.825( mm ) number of nodes per spring coil 4 13
DOHC(Double Over Head Cam) Fig. 3.1, Fig. 3.2 SCXI 1211 (signal)pc Labview Fig. 3.1 Schematic of Engine experimental device 14
Fig. 3.2 Data acquisition device (amplification) (filter) SCXI 1211 DAQ Labview Oil Inlet Path Oil Drain Path 15
Engine oil circulation Engine operation Motor DOHC ENGINE Accelerometer LVDT Encoder Strain gage Amplifier1 Amplifier2 SXCI 1211 MODULE Data acquisition DAQ Board Data storage Fig. 3.3 Data acquisition path 16
Fig. 3.4 Cylinder head (DOHC) Fig. 3.5 Tappet, Retainer, Valve spring, Split key, Valve guide, Intake valve, Exhaust valve 17
Table 3.1 Experimental device specification Sort Model Character Maker strain gage AE-11-S10S-120-EC gage factor : 2.0 resistance : 120Ω CAS accelerometer 8742A5 Mv/ g =1 100 khz KISTLER encoder ENB-360-3-1 100 khz AUTONICS NI board ATMIO-16E-10 10 khz NI module SCXI1121 10 khz NI spring tester VST-120B 0kgf ~ 120 kgf OKUDA KOKI LVDT Solartron AX/10/S voltage±10 Solartron motor three phase MOTOR 7.5KW Hyosung motor controller LG is3 220V LG 18
Table 3.2 The role of experimental device Sort strain Gage accelerometer encoder NI board SCXI 1121 module spring tester LVDT motor Mv/ g Role (quartz sensing element) (seismic) (flexible coupling) (pulse) SCXI1211 (module) DAQ (transfer) rpm motor controller P C Labview 19
(force) PCLabview Table 3.3 Valve spring dimension Valve spring Dimension outer diameter (m ) 0.02695 inner deameter (m ) 0.0187 mean diameter (m ) 0.022825 height (m ) 0.0405 total length ( m ) 0.4817 active coil 5 K ( N / m ) 35854 wire long diameter (m ) 0.004125 wire short diameter (m ) 0.0033 wire mean diameter (m ) 0.0037125 20
Table 3.4 Valve, Tappet, Retainer mass Component Mass( g ) intake valve 42.04 exhaust valve 36.52 tappet 49.34 retainer 12.84 Fig. 3.6 Schematic of valve spring tester 21
K Table 3.5 Valve spring height Load( kgf ) Load( N ) Displacement(mm ) Height(mm ) 0 0 0.00 40.50 5 49 2.00 38.50 10 98 4.00 36.50 15 147 6.00 34.50 20 196 7.00 33.50 25 245 8.00 32.50 30 294 9.00 31.50 35 343 11.00 29.50 40 392 12.00 28.50 45 441 12.50 27.00 50 490 15.00 25.50 55 539 15.50 25.00 60 588 17.00 23.50 kgf (height) kgf N N / m (curve fitting) 22
600 500 spring constant 400 N 300 200 100 curve fit 35.854x-34.206 0 0 5 10 15 20 mm Fig. 3.7 Spring constant K=35854( N / m ) N mm kgf N SCXI 1211 23
Table 3.6 Top (pitch) TopBottom Bottom (hole) (motor controller) Fig. 3.8 Schematic of strain gage attachment position 24
Table 3.6 Strain gage attachment position on valve spring(static state) Case Front Plane Side mm mm 25
mm mm kgf mm kgf kgf kgf N mm N mm N (cap) N mm N mm N rpm Fig. 3.9 Schematic of washer position for preload 26
27 (accelerometer) Labview Fig. 3.10 Schematic of accelerometer attachment position
Fig. 3.10 PC Labview 3 10 9.8 10 2 1V = ( m / s ) 28
29 Fig. 3.11 (encoder) Z Labview Fig. 3.11 Schematic of encoder experimental device
(Linear Variable Differential Transformer) Fig. 3.12 Fig. 3.12 Schematic of LVDT attachment position 30
SCXI DAQ (display) 31
Labview Labview (Version) Labview (front panel) (block diagram) Fig. 3.13 (scan rate) (buffer size), (gage factor) (voltage) (bridge type) (filter) Fig. 3.13 Labview program (front panel) 32
Fig. 3.14 Labview program(block diagram) Fig. 3.14 Labview Labview VI ForCase AI MULTPT ±V AI MULTPT For (build array) STRAIN CONV 33
34 Labview rpm 600 rpm 300 60 )/ 360 ( rpm labview (low pass filter)
5.0 10-3 4.0 10-3 3.0 10-3 case 1 case 2 case 3 case 4 Strain 2.0 10-3 1.0 10-3 0.0 10 0-1.0 10-3 0 10 20 30 40 50 60 70 (kgf) Fig. 4.1 Spring strain at static loading(1) 3.0 10-4 2.0 10-4 case 5 case 6 case 7 case 8 Strain 1.0 10-4 0.0 10 0-1.0 10-4 0 10 20 30 40 50 60 70 (kgf) Fig. 4.2 Spring strain at static loading(2) 35
1.0 10-2 8.0 10-3 6.0 10-3 case 9 case 10 case 11 case 12 Strain 4.0 10-3 2.0 10-3 0.0 10 0-2.0 10-3 0 10 20 30 40 50 60 70 (kgf) Fig. 4.3 Spring strain at static loading(3) kgf Fig. 4.4 ~ Fig. 4.9 36
2.5 10-5 2.0 10-5 1.5 10-5 preload260n preload300n preload340n strain 1.0 10-5 5.0 10-6 0.0 10 0-5.0 10-6 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.4 Spring force at 600rpm 2.5 10-5 2.0 10-5 1.5 10-5 preload260n preload300n preload340n strain 1.0 10-5 5.0 10-6 0.0 10 0-5.0 10-6 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.5 Spring force at 800 rpm 37
2.5 10-5 2.0 10-5 1.5 10-5 preload260n preload300n preload340n strain 1.0 10-5 5.0 10-6 0.0 10 0-5.0 10-6 -1.0 10-5 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.6 Spring force at 1000 rpm 2.5 10-5 2.0 10-5 1.5 10-5 600rpm 800rpm 1000rpm strain 1.0 10-5 5.0 10-6 0.0 10 0-5.0 10-6 -1.0 10-5 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.7 Spring force at preload 260 N 38
1.5 10-5 1.0 10-5 600rpm 800rpm 1000rpm strain 5.0 10-6 0.0 10 0-5.0 10-6 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.8 Spring force at preload 300 N 1.0 10-5 5.0 10-6 600rpm 800rpm 1000rpm strain 0.0 10 0-5.0 10-6 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.9 Spring force at preload 340 N 39
40
1200rpm 2000rpm 2800rpm Fig. 4.10Fig. 4.11 3.0 10 3 acceleration (m/s^2) 2.5 10 3 2.0 10 3 1.5 10 3 1.0 10 3 5.0 10 2 0.0 10 0-5.0 10 2-1.0 10 3 1200rpm 2000rpm 2800rpm 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.10 Intake valve acceleration 3.0 10 3 acceleration (m/s^2) 2.5 10 3 2.0 10 3 1.5 10 3 1.0 10 3 5.0 10 2 0.0 10 0-5.0 10 2-1.0 10 3 1200rpm 2000rpm 2800rpm 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.11 Exhaust valve acceleration 41
rpm Fig. 4.12 (valve seat).,. 0.015 1500 cam profile (m) 0.012 0.009 0.006 0.003 0-0.003 cam profile exhaust intake 1200 900 600 300 0-300 valve acceleration (m/s^2) -0.006-600 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.12 Cam lift and valve acceleration at 2000 rpm 42
0.015 1500 cam profile (m) 0.012 0.009 0.006 0.003 0-0.003 cam profile exhaust intake 1200 900 600 300-300 -0.006-600 0 12 24 36 48 60 cam angle (degree) 0 valve acceleration (m/s^2) Fig. 4.13 Cam lift and valve acceleration at valve opening range (2000 rpm ) cam profile (m) 0.015 0.012 0.009 0.006 0.003 0-0.003 cam profile 1500 1200 900 600 300-300 -0.006-600 90 100 110 120 130 140 150 160 cam angle (degree) exhaust intake 0 valve acceleration (m/s^2) Fig. 4.14 Cam lift and valve acceleration at valve closing range (2000 rpm ) 43
Fig. 4.15 (cam) (start point) 30 20 encoder acceleration Voltage 10 0-10 0 900 1800 2700 3600 4500 Time Fig. 4.15 Signals of encoder, valve acceleration at 800 rpm 44
,. Fig. 4.16. Fig. 4.17 ~ Fig.4.19,,... (flexibility) DOHC. 10 valve lift(mm) 8 6 4 2 800rpm 1600rpm 2400rpm 0-2 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.16 Valve lift 45
8.8 valve lift(mm) 8.7 8.6 8.5 8.4 800rpm 1600rpm 2400rpm 8.3 8.2 50 55 60 65 70 75 80 cam angle (degree) Fig. 4.17 Valve lift at cam maximum lift range 0.8 valve lift(mm) 0.6 0.4 0.2 800rpm 1600rpm 2400rpm 0-0.2 0 4 8 12 16 20 cam angle (degree) Fig. 4.18 Valve lift at valve opening range 46
3 valve lift(mm) 2 1 0 800rpm 1600rpm 2400rpm -1 110 115 120 125 130 135 140 cam angle (degree) Fig. 4.19 Valve lift at valve closing range.,... 47
Fig. 4.20 ~ Fig. 4.23 600 550 undamped viscous damping spring force(n) 500 450 400 350 300 250 0 60 120 180 240 300 360 cam angle(degree) 700 Fig. 4.20 Valve spring force at 2000 rpm spring force(n) 600 500 400 300 undamped viscous damping 200 100 0 60 120 180 240 300 360 cam angle(degree) Fig. 4.21 Valve spring force at 4000 rpm 48
700 600 undamped viscous damping spring force(n) 500 400 300 200 100 0 60 120 180 240 300 360 700 cam angle(degree) Fig. 4.22 Valve spring force at 6000 rpm spring force (N) 600 500 400 300 200 2000rpm 4000rpm 6000rpm 100 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.23 Valve spring force at viscous damping,... 49
(ValDyn) (seat force) (cam & tappet contact force) DOHC Fig. 4.24 ~ Fig. 4.30 700 spring force (N) 600 500 400 300 4000rpm 6000rpm 200 100 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.24 Valve spring force 50
cam & tappet contact force (N) 2000 1500 1000 500 0 4000rpm 6000rpm -500 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.25 Cam & tappet contact force 350 seat force (N) 300 250 200 150 100 50 4000rpm 6000rpm 0-50 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.26 Valve seat force 51
valve lift (mm) 10 8 6 4 2 0 4000rpm 6000rpm -2 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.27 Valve lift 15000 acceleration (m/s^2) 10000 5000 0 4000rpm 6000rpm -5000 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.28 Valve acceleration 52
5 valve velocity (m/s) 2.5 0-2.5 4000rpm 6000rpm -5 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.29 Valve velocity 1 valve velocity (m/s) 0.5 0-0.5-1 -1.5 4000rpm 6000rpm -2 120 125 130 135 140 cam angle (degree) Fig. 4.30 Valve velocity at valve closing range 53
2500 acceleration(m/s^2) 2000 1500 1000 500 0-500 ricardo(2800rpm) experiment(2800rpm) -1000-1500 0 60 120 180 240 cam angle(degree) 300 360 Fig. 4.31 Valve acceleration (Ricardo software & experiment) 10 8 ricardo (2800rpm) experiment (2800rpm) valve lift (mm) 6 4 2 0-2 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.32 Valve lift (Ricardo software & experiment) 54
700 600 Numeric (4000rpm) Ricardo (4000rpm) spring force (N) 500 400 300 200 100 0 60 120 180 240 300 360 cam angle (degree) Fig. 4.33 Valve spring force(ricardo software & numerical method) Fig. 4.31 Fig. 4.32 Fig. 4.33.. 55
56 (engine oil) (flexibility) DOHC
References 1. R. S. Paranjpe, Dynamic Analysis of a Valve Spring With a Coulomb Friction Damper, Journal of Mechanical Design, Vol. 112, pp509-513, December 1990 2. A. P. Pisano & Freudenstein, An Experimental and Analytical Investigation of the Dynamic Response of a High Speed Cam Follower System, Transaction of the ASME, Vol. 105, pp692-698, December 1983 3. A. P. Pisano, Coulomb Friction in High Speed Cam systems, Transaction of the ASME, Vol. 106, pp470-474, December 1984 4. Shervin Hanchi & Ferdinand Freudenstein, The Development of a Predictive Model for the Optimization of High Speed Cam Follower Systems with Coulomb Damping Internal Friction and Elastic and Fluidic Elements, Transaction of the ASME, Vol.108, pp506-515, December 1986 5. J. Lee & D.J.Patterson, Nonlinear Valve Train Dynamics Simulation With a Distributed Parameter Model of Valve Springs, Transaction of the ASME, Vol. 119, July 1997 6. Harold A. Rothbart, Cams Design, Dynamics, and Accuracy, NEWYORK JOHN WILEY & SONS, Inc., LONDON-CHAPMAN & HALL, LIMITED., 1987 7. In-Soo Suh, An Investigation of Sound Quality of I.C. Engines, MASSACHUSETTS INSTITUTE OF TECHNOLOGY, Doctor of Philosophy, February 1998 57
8. Whal, A. M., Mechanical Springs, Penton Publishing Company, Cleveland, Ohio, 1994 9. Ming Hsun Wu, Jing Yuan Ho, Wensyang Hsu, General Equations of a Helical Spring With a Cup Damper and Static Verification, Journal of Mechanical Design, Vol. 119, pp319-326, June 1997 10. Ricardo Manual, VALDYN VERSION 2.1, pp B-93, 1999 11. J. P. Holman, Experimental Methods for Engineers, McGRAW-HILL INTERMATIONAL EDITIONS, 1994 12. DAQ Getting Started with SCXI, NATIONAL INSTRUMENTS, June 1996 Vol No pp 58
Abstract A Study on the Nonlinear Dynamic Characteristics of DOHC Engine Valve Train system by Sangryang Cha The professional Graduate School of Automotive Engineering Kookmin University Seoul, Korea The dynamic characteristics of valve train system is very important for the optimization automobile engine design because the characteristics affect directly and significantly not only on engine efficiency but also on the generally noise. Since the valve train operates with varying engine speed and it consists of spring and lumped masses, the dynamic performance should be checked to analyze valve train system. Especially, valve spring brought out a nonlinear phenomena by surging. The objective of this study is to analyze the dynamic characteristics of valve train system through an experiment and simulation. we have analyzed the characteristics of valve train system including both the nonlinear characteristics of valve spring and cam profile. In order to find out the valve spring behavior, we develop the test rig of valve train system and numerical computing software. From the experimental results, it is found that valve spring is greatly effected by the magnitude of preload. The nonlinear dynamic characteristics such as surging phenomena is very related to cam profile and stiffness and damping of each components. In the numerical study, we find good coincidence of tendency to the experimental results with respects of the nonlinear behavior tendency. 59