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1 DOHC A Study on the Nonlinear Dynamic Characteristics of DOHC Engine Valve Train System 2000

2 DOHC (A Study on the Nonlinear Dynamic Characteristics of DOHC Engine Valve Train System)

4 ..... i Nomenclature..... iv List of figures.....vi List of tables......viii I Surging Quarter Bridge i

5 References Abstract... ii

6 DOHC(Double Over Head Camshaft) (surging) (strain gage) (preload). (washer) (accelerometer) (LVDT) (node) rpm (cam) (tappet) (valve) spring) (component) (ValDyn) (cam profile) iii

7 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

8 ξ : viscous damping factor ε : strain ω 1 : first natural frequency, Hz v

9 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 Schematic of accelerometer attachment position Fig Schematic of encoder experimental device Fig Schematic of LVDT attachment position Fig Labview program (front panel) Fig 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

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.

10 Fig. 4.8 Spring force at preload 300 N Fig. 4.9 Spring force at preload 340 N Fig Intake valve acceleration Fig Exhaust valve acceleration Fig Cam lift and valve acceleration at 2000 rpm Fig Cam lift and valve acceleration at valve opening range (2000 rpm ) Fig Cam lift and valve acceleration at valve closing range (2000 rpm ) Fig Signals of encoder, valve acceleration at 800 rpm Fig Valve lift Fig Valve lift at cam maximum lift range Fig Valve lift at valve opening range Fig Valve lift at valve closing range Fig Valve spring force at 2000 rpm Fig Valve spring force at 4000 rpm Fig Valve spring force at 6000 rpm Fig Valve spring force at viscous damping Fig Valve spring force Fig Cam & tappet contact force Fig Valve seat force Fig Valve lift Fig Valve acceleration Fig Valve velocity Fig Valve velocity at valve closing range Fig Valve acceleration(ricardo software & experiment) Fig Valve lift(ricardo software & experiment) Fig Valve spring force(ricardo software & numerical method vii

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.

11 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 Experimental device specification Table 3.2 The role of experimental device Table 3.

12 1 (surging) (dynamic) (component)

13 2 DOHC (push rod) (OHC) (ValDyn) (valve timing) (volumetric flow) (component) (motion) (displacement)

14 (coulomb) (viscous) m Q (inertia force) df a = 2 2 γ πd y ds 2 g 4 t Fig. 2.1 Valve spring 3

15 (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 γ πd y ' y y + c = kπdn 2 2 g 4 t t a s 2 y t + c y = α t 2 eq y s 4

(damping force) y t = c ' ds df d df = df df a b d 2 2 2 γ πd y

16 5 (start motion) Fig (contact motion) Fig (jump motion) Fig (linkage) (bounce motion) Fig

17 start motion contact jump motion bounce Fig. 2.2 Schematic of valve train motions 6

18 7 (surging) (wire) (residual stress) (steel) (spring stiffness)

19 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

20 (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

21 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 Cam Profile 6 mm Cam angle (degree) Fig. 2.4 Input cam profile 10

22 Table 2.1 Input cam profile Lift(m) Lift(m) Lift(m) Lift(m) Lift(m) Lift(m)

23 (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

24 Table 2.2 Ricardo input data for each parameters Parameter Data cam stiffness ( N / mm ) cam damping ( 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 ( N / mm ) seat damping 532( N s / mm ) tappet mass(retainer ) g valve spring mass valve mass preload spring material shear modules 38.8 g g 260 N MPa fraction of critical damping( ξ ) material density ( kg / m ) wire diameter ( mm ) mean coil diameter ( mm ) number of nodes per spring coil 4 13

25 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

26 Fig. 3.2 Data acquisition device (amplification) (filter) SCXI 1211 DAQ Labview Oil Inlet Path Oil Drain Path 15

27 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

28 Fig. 3.4 Cylinder head (DOHC) Fig. 3.5 Tappet, Retainer, Valve spring, Split key, Valve guide, Intake valve, Exhaust valve 17

29 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 khz AUTONICS NI board ATMIO-16E khz NI module SCXI 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

30 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

31 (force) PCLabview Table 3.3 Valve spring dimension Valve spring Dimension outer diameter (m ) inner deameter (m ) mean diameter (m ) height (m ) total length ( m ) active coil 5 K ( N / m ) wire long diameter (m ) wire short diameter (m ) wire mean diameter (m )

32 Table 3.4 Valve, Tappet, Retainer mass Component Mass( g ) intake valve exhaust valve tappet retainer Fig. 3.6 Schematic of valve spring tester 21

33 K Table 3.5 Valve spring height Load( kgf ) Load( N ) Displacement(mm ) Height(mm ) kgf (height) kgf N N / m (curve fitting) 22

34 spring constant 400 N curve fit x mm Fig. 3.7 Spring constant K=35854( N / m ) N mm kgf N SCXI

35 Table 3.6 Top (pitch) TopBottom Bottom (hole) (motor controller) Fig. 3.8 Schematic of strain gage attachment position 24

36 Table 3.6 Strain gage attachment position on valve spring(static state) Case Front Plane Side mm mm 25

37 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

38 27 (accelerometer) Labview Fig Schematic of accelerometer attachment position

39 Fig PC Labview V = ( m / s ) 28

40 29 Fig (encoder) Z Labview Fig Schematic of encoder experimental device

41 (Linear Variable Differential Transformer) Fig Fig Schematic of LVDT attachment position 30

42 SCXI DAQ (display) 31

43 Labview Labview (Version) Labview (front panel) (block diagram) Fig (scan rate) (buffer size), (gage factor) (voltage) (bridge type) (filter) Fig Labview program (front panel) 32

44 Fig Labview program(block diagram) Fig Labview Labview VI ForCase AI MULTPT ±V AI MULTPT For (build array) STRAIN CONV 33

45 34 Labview rpm 600 rpm )/ 360 ( rpm labview (low pass filter)

46 case 1 case 2 case 3 case 4 Strain (kgf) Fig. 4.1 Spring strain at static loading(1) case 5 case 6 case 7 case 8 Strain (kgf) Fig. 4.2 Spring strain at static loading(2) 35

47 case 9 case 10 case 11 case 12 Strain (kgf) Fig. 4.3 Spring strain at static loading(3) kgf Fig. 4.4 ~ Fig

48 preload260n preload300n preload340n strain cam angle (degree) Fig. 4.4 Spring force at 600rpm preload260n preload300n preload340n strain cam angle (degree) Fig. 4.5 Spring force at 800 rpm 37

49 preload260n preload300n preload340n strain cam angle (degree) Fig. 4.6 Spring force at 1000 rpm rpm 800rpm 1000rpm strain cam angle (degree) Fig. 4.7 Spring force at preload 260 N 38

50 rpm 800rpm 1000rpm strain cam angle (degree) Fig. 4.8 Spring force at preload 300 N rpm 800rpm 1000rpm strain cam angle (degree) Fig. 4.9 Spring force at preload 340 N 39

51 40

52 1200rpm 2000rpm 2800rpm Fig. 4.10Fig acceleration (m/s^2) rpm 2000rpm 2800rpm cam angle (degree) Fig Intake valve acceleration acceleration (m/s^2) rpm 2000rpm 2800rpm cam angle (degree) Fig Exhaust valve acceleration 41

53 rpm Fig (valve seat)., cam profile (m) cam profile exhaust intake valve acceleration (m/s^2) cam angle (degree) Fig Cam lift and valve acceleration at 2000 rpm 42

54 cam profile (m) cam profile exhaust intake cam angle (degree) 0 valve acceleration (m/s^2) Fig Cam lift and valve acceleration at valve opening range (2000 rpm ) cam profile (m) cam profile cam angle (degree) exhaust intake 0 valve acceleration (m/s^2) Fig Cam lift and valve acceleration at valve closing range (2000 rpm ) 43

55 Fig (cam) (start point) encoder acceleration Voltage Time Fig Signals of encoder, valve acceleration at 800 rpm 44

56 ,. Fig Fig ~ Fig.4.19,,... (flexibility) DOHC. 10 valve lift(mm) rpm 1600rpm 2400rpm cam angle (degree) Fig Valve lift 45

57 8.8 valve lift(mm) rpm 1600rpm 2400rpm cam angle (degree) Fig Valve lift at cam maximum lift range 0.8 valve lift(mm) rpm 1600rpm 2400rpm cam angle (degree) Fig Valve lift at valve opening range 46

58 3 valve lift(mm) rpm 1600rpm 2400rpm cam angle (degree) Fig Valve lift at valve closing range.,... 47

59 Fig ~ Fig undamped viscous damping spring force(n) cam angle(degree) 700 Fig Valve spring force at 2000 rpm spring force(n) undamped viscous damping cam angle(degree) Fig Valve spring force at 4000 rpm 48

60 undamped viscous damping spring force(n) cam angle(degree) Fig Valve spring force at 6000 rpm spring force (N) rpm 4000rpm 6000rpm cam angle (degree) Fig Valve spring force at viscous damping,... 49

61 (ValDyn) (seat force) (cam & tappet contact force) DOHC Fig ~ Fig spring force (N) rpm 6000rpm cam angle (degree) Fig Valve spring force 50

62 cam & tappet contact force (N) rpm 6000rpm cam angle (degree) Fig Cam & tappet contact force 350 seat force (N) rpm 6000rpm cam angle (degree) Fig Valve seat force 51

63 valve lift (mm) rpm 6000rpm cam angle (degree) Fig Valve lift acceleration (m/s^2) rpm 6000rpm cam angle (degree) Fig Valve acceleration 52

64 5 valve velocity (m/s) rpm 6000rpm cam angle (degree) Fig Valve velocity 1 valve velocity (m/s) rpm 6000rpm cam angle (degree) Fig Valve velocity at valve closing range 53

65 2500 acceleration(m/s^2) ricardo(2800rpm) experiment(2800rpm) cam angle(degree) Fig Valve acceleration (Ricardo software & experiment) 10 8 ricardo (2800rpm) experiment (2800rpm) valve lift (mm) cam angle (degree) Fig Valve lift (Ricardo software & experiment) 54

66 Numeric (4000rpm) Ricardo (4000rpm) spring force (N) cam angle (degree) Fig Valve spring force(ricardo software & numerical method) Fig Fig Fig

67 56 (engine oil) (flexibility) DOHC

68 References 1. R. S. Paranjpe, Dynamic Analysis of a Valve Spring With a Coulomb Friction Damper, Journal of Mechanical Design, Vol. 112, pp , December 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, pp , December A. P. Pisano, Coulomb Friction in High Speed Cam systems, Transaction of the ASME, Vol. 106, pp , December 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, pp , December 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 Harold A. Rothbart, Cams Design, Dynamics, and Accuracy, NEWYORK JOHN WILEY & SONS, Inc., LONDON-CHAPMAN & HALL, LIMITED., In-Soo Suh, An Investigation of Sound Quality of I.C. Engines, MASSACHUSETTS INSTITUTE OF TECHNOLOGY, Doctor of Philosophy, February

69 8. Whal, A. M., Mechanical Springs, Penton Publishing Company, Cleveland, Ohio, 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, pp , June Ricardo Manual, VALDYN VERSION 2.1, pp B-93, J. P. Holman, Experimental Methods for Engineers, McGRAW-HILL INTERMATIONAL EDITIONS, DAQ Getting Started with SCXI, NATIONAL INSTRUMENTS, June 1996 Vol No pp 58

70 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

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