Model-Based Design, Modelling and Simulation of Digital Hydraulic Gas Admission Valve

155 Pages·2014·6.91 MB·English

by  Jussi Peurala

JUSSI PEURALA
MODEL-BASED DESIGN, MODELLING AND SIMULATION OF
DIGITAL HYDRAULIC GAS ADMISSION VALVE
Master of Science Thesis

Examiner: Adj. Prof. Matti Linjama

Examiner and topic were approved

by the Faculty Council of the Faculty

of Engineering sciences on 6th of

March 2014
ii

TIIVISTELMÄ

TAMPEREEN TEKNILLINEN YLIOPISTO
Konetekniikan koulutusohjelma
PEURALA, JUSSI: Model-Based Design, Modelling and Simulation of Digital
Hydraulic Gas Admission Valve
Diplomityö, 132 sivua, 12 liitesivua
Toukokuu 2014
Pääaine: Hydrauliikka ja automatiikka, hydraulitekniikka
Tarkastaja: Dosentti Matti Linjama
Avainsanat Digitaalihydrauliikka, pneumatiikka, pääkaasuventtiili, mallipohjainen
suunnittelu, CFD

Kaasumoottorin pääkaasuventtiili on strategisesti tärkeä komponentti. Hyvän venttiilin
ominaisuuksiin kuuluvat esimerkiksi pieni vasteaika, suuri läpäisy, mahdollisuus toimia
suurellakin paine-erolla ja vikasietoisuus. Nykyisen solenoidiohjatun pääkaasuventtiilin
vasteaika on pieni ja virtauskapasiteetti suuri, mutta suurin ongelma on se, ettei venttiili
avaudu jos paine-ero venttiilin yli on liian suuri.

Tämän työn tarkoituksena on suunnitella, mallintaa ja simuloida uudentyyppinen
pääkaasuventtiili, joka hyödyntää digitaalisuuden periaatetta. Työn sovelluksessa
imuventtiiliin on integroitu kaasu-urat, joiden kautta kaasu pääsee virtaamaan moottorin
sylinteriin. Imuventtiilin ohjaus toteutetaan digitaalihydrauliikalla.

Työn toisena sovelluksena esitellään digitaalipneumaattinen pääkaasuventtiili.
Digitaaliventtiili on toteutettu binäärikoodattuna digitaalisena
tilavuusvirransäätöyksikkönä.

Kuten työn tulokset osoittavat, digitaalihydraulinen imuventtiili kaasu-urilla on
realistinen konstruktio. Sekä virtaus- että simulointitulokset osoittavat, että konstruktio
on toimiva ja valmistuskelpoinen.

Tämä diplomityö on tehty osana FIMECC EFFIMA -Digihybrid –tutkimusprojektia.
FIMECCin tarkoituksena on lisätä ja syventää yhteistyötä yritysten, yliopistojen ja
tutkimusinstituuttien tutkimus- ja kehitysosastojen välillä. EFFIMAn tarkoituksena on
kehittää energiatehokkaita koneita ja laitteita ja energiatehokkuus on projektin
avainsana. Tässä työssä energiatehokkuus on toteutettu älykkäällä ohjaustavalla
säästäen energiaa.
iii

ABSTRACT

TAMPERE UNIVERSITY OF TECHNOLOGY
Master’s Degree Programme in Mechanical engineer
PEURALA, JUSSI: Model-Based Design, Modelling and Simulation of Digital
Hydraulic Gas Admission Valve
Master of Science Thesis, 132 pages, 12 Appendix pages
May 2014
Major: Hydraulics and automation, fluid power
Examiner: Adj. Prof. Matti Linjama
Keywords: Digital hydraulics, pneumatics, gas admission valve, model-based
design, CFD

Gas admission valve is strategically important component on gas engine. Short response
time, large flow rate capacity through the valve, ability to work at large pressure differ-
ence and fault tolerant are characteristics that a good valve should be fulfilled. The so-
lenoid based gas admission valve used at the moment has short response time and large
flow rate capacity but the main problem is that if pressure difference over the valve is
too large, the valve will not open.

The goal of this thesis is to design, model and simulate a new gas admission valve
which utilizes the principle of digitalization. The application of the thesis is an intake
valve which has been integrated gas flow edges. Through the flow edges the gas flows
into the engine’s cylinder. The control of the intake valve is realized by using digital
hydraulics.

The second application of the thesis is digital pneumatic gas admission valve. The valve
is realized by using binary coded digital flow control unit.

As the results show, digital hydraulic intake air valve with gas flow edges is a realistic
construction. Both flow and simulation results indicate that the construction is func-
tional and possible to manufacture.

This thesis has been done as a part of FIMECC EFFIMA Digihybrid research project.
The target of FIMECC is to increase and deepen the cooperation between companies,
universities and research institutes in R&D. The target of EFFIMA is to develop energy
efficient machines and devices and the key word of the project is energy efficient. In
this thesis energy efficient has been realized by using intelligent controller.
iv

PREFACE

This thesis was done for Wärtsilä Finland R&D Research & Innovation Management
under the program Intelligent Engine where the program manager is Jonatan Rösgren. I
want to thank my thesis supervisor Harry Särs for giving me this opportunity to work at
Wärtsilä. We both taught each other many new things. I hope that we can be friends also
in the future. I want also thank Håkan Nynäs. You gave me so many new ideas and you
taught me to think in a new way. Antonino Di Miceli and Lars Ola Liavåg deserve spe-
cial thanks about CFD results. Jari Hyvönen and Daniel Häggblom, thank you about the
initial idea of gas flow edges and conversations during the work. I would like to thank
also my examiner Matti Linjama for examine the thesis.

I would like to thank my friends and my sisters Hanna and Emma. You have always
helped me on good and bad times and gave me energy during the studying.

My deepest thanks belong to my parents, Tuula and Antti: Without you I could not ever
been graduated to Master of Science in Engineering. I dedicate this thesis to you!

In Vaasa, 14.4.2014

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Jussi Peurala
v

CONTENTS

Abstract ............................................................................................................................ iii
Symbols and abbreviations ............................................................................................ viii
1 Introduction ............................................................................................................... 1
2 Gas engine ................................................................................................................. 3
2.1 Gas engine types ............................................................................................... 4
2.1.1 Gas-Diesel engine ................................................................................ 4
2.1.2 Dual-fuel engine .................................................................................. 6
2.1.3 Spark-ignition gas engine .................................................................... 7
2.2 Miller cycle ....................................................................................................... 8
2.3 Methane burning equations ............................................................................. 10
2.4 Gas injection systems ...................................................................................... 12
2.4.1 Single-point injection ......................................................................... 13
2.4.2 Multi-point injection .......................................................................... 14
2.4.3 Constructions of single- and multi-point injection systems............... 15
2.5 Methane slip .................................................................................................... 16
2.5.1 Reduction of piston topland ............................................................... 17
2.5.2 Quenching distance ............................................................................ 17
2.5.3 Gas permeation membrane ................................................................ 18
2.6 Knocking on gas engine .................................................................................. 21
2.7 Gas admission valve ........................................................................................ 24
2.7.1 SOGAV 250 ....................................................................................... 24
2.7.2 Required features ............................................................................... 25
3 Digital fluid power .................................................................................................. 27
3.1 Flow control techniques .................................................................................. 29
3.1.1 PWM .................................................................................................. 29
3.1.2 PFM ................................................................................................... 30
3.1.3 PCM ................................................................................................... 30
3.1.4 PNM ................................................................................................... 31
3.2 Solenoid based valve ....................................................................................... 31
3.2.1 Theory of a solenoid .......................................................................... 32
3.2.2 Boosting a solenoid ............................................................................ 32
3.3 Miniaturization ................................................................................................ 35
3.3.1 Theory of miniaturization .................................................................. 35
3.4 Commercial and non-commercial digital valves............................................. 36
3.4.1 Bucher Hydraulics Series WS22GD/OD ........................................... 37
3.4.2 Sturman Industries SI-1000 ............................................................... 38
3.4.3 Bibus Matrix series 850 pneumatic valve .......................................... 40
4 Modelling equations ................................................................................................ 41
4.1 Proportional controller .................................................................................... 41
4.2 Controller equations using two DFCUs .......................................................... 41
vi

4.2.1 Steady-state flow rates ....................................................................... 41
4.2.2 Cost functions .................................................................................... 42
4.3 Controller equations using four DFCUs ......................................................... 42
4.3.1 Mode selection ................................................................................... 42
4.3.2 Steady-state solver ............................................................................. 47
4.3.3 Cost functions .................................................................................... 48
4.4 Hydraulic system equations ............................................................................ 49
4.4.1 Orifice ................................................................................................ 49
4.4.2 Hydraulic cylinder ............................................................................. 49
4.4.3 Load ................................................................................................... 50
4.4.4 Hyperbolic tangent friction function.................................................. 50
4.4.5 Damping............................................................................................. 50
4.4.6 Energy consumption .......................................................................... 50
4.5 Poppet valve .................................................................................................... 51
4.5.1 Poppet valve lift and area equations .................................................. 51
4.5.2 Gas flow edge area ............................................................................. 52
4.5.3 Gas flow equations............................................................................. 53
4.6 Pneumatic valve .............................................................................................. 53
5 Simulation models ................................................................................................... 55
5.1 Model-based control design ............................................................................ 56
5.2 Digital hydraulic system using two DFCUs.................................................... 56
5.2.1 Short-circuit flow controller .............................................................. 58
5.2.2 Position controller .............................................................................. 59
5.3 Digital hydraulic system using four DFCUs ................................................... 61
5.3.1 Model-based valve controller ............................................................ 62
5.3.2 Mode selection ................................................................................... 63
5.3.3 Steady-state solver ............................................................................. 65
5.3.4 Cost function and optimal control ..................................................... 66
5.4 Hydraulic system model .................................................................................. 67
5.4.1 Supply pressure model ....................................................................... 67
5.4.2 Model of valve dynamics ................................................................... 68
5.4.3 Orifice ................................................................................................ 71
5.4.4 Hydraulic cylinder model .................................................................. 71
5.4.5 Cylinder friction model ...................................................................... 72
5.4.6 Load model ........................................................................................ 72
5.4.7 Damping model.................................................................................. 73
5.5 Poppet valve .................................................................................................... 74
5.5.1 Poppet valve geometry....................................................................... 74
5.5.2 Gas flow equations............................................................................. 76
5.5.3 Area of gas flow edges....................................................................... 76
5.5.4 Simulation model of poppet valve ..................................................... 77
5.6 Solenoid based gas admission valve ............................................................... 79
vii

5.6.1 Modelling of solenoid based gas admission valve............................. 80
5.6.2 Simulation model, PCM –coded ........................................................ 81
5.6.3 Modelling of pneumatic equations .................................................... 81
6 Simulation results of the systems ............................................................................ 83
6.1 Digital hydraulic system using two DFCUs.................................................... 83
6.1.1 Simulation results using supply pressure 30 MPa ............................. 84
6.1.2 Simulation results using supply pressure 25 MPa ............................. 88
6.2 Digital hydraulic system using four DFCUs ................................................... 94
6.2.1 Simulation results using supply pressure 30 MPa ............................. 94
6.2.2 Simulation results with supply pressure 25 MPa ............................. 100
6.3 Simulation results using digital pneumatic valve system ............................. 106
6.4 Comparison of energy consumptions ............................................................ 108
6.4.1 Comparison to digital hydraulic valve train .................................... 108
6.4.2 Comparison to proportional valve train ........................................... 109
6.4.3 Comparison to mechanical valve train............................................. 110
6.4.4 Conclusion of energy comparison ................................................... 110
6.5 Comparison of velocity error using digital hydraulic systems ..................... 110
7 CFD results ........................................................................................................... 112
7.1 Defining the discharge coefficient ................................................................ 112
7.2 Different poppet valve lifts ........................................................................... 114
7.2.1 Valve lift 5 mm ................................................................................ 114
7.2.2 Valve lift 6 mm ................................................................................ 116
7.2.3 Valve lift 7.5 mm ............................................................................. 117
7.2.4 Valve lift 8.5 mm ............................................................................. 119
7.2.5 Valve lift 10 mm .............................................................................. 120
7.2.6 Valve lift 15 mm .............................................................................. 122
7.3 Comparing steady-state flow rates ................................................................ 123
8 Conclusions ........................................................................................................... 126
References ..................................................................................................................... 128
Appendix A: DFCU state matrix................................................................................... 133
Appendix B: Combination of vectors ........................................................................... 134
Appendix C: Finding minimum index .......................................................................... 135
Appendix D: Poppet valve forces and initial chamber pressures .................................. 136
Appendix E: Poppet valve gas edges and inlet valve parameters ................................. 137
Appendix F: Gas amount calculations .......................................................................... 138
Appendix G: Hydraulic simulation models, common parameters ................................ 139
Appendix H: Specific simulation parameters, 2 X DFCU, supply pressure 30 MPa ... 140
Appendix I: Specific simulation parameters, 2 X DFCU, supply pressure 25 MPa ..... 141
Appendix J: Specific simulation parameters, 4 X DFCU, supply pressure 30 MPa ..... 142
Appendix K: Specific simulation parameters, 4 X DFCU, supply pressure 25 MPa ... 143
Appendix L: Specific simulation parameters, pneumatic system ................................. 144
viii

SYMBOLS AND ABBREVIATIONS

Variables

a Acceleration m/s2
a Amount of gas flow edges -
e
A Outlet of cross sectional area m2
A A-chamber area m2
A
A B-chamber area m2
B
A Flow area of poppet valve m2
m
A Gas flow area m2
gas
A Real gas flow area m2
real
A Flow area for defining discharge coefficient m2
T
A Area of inner gas flow edge m2
1
A Area of outer gas flow edge m2
2
b Viscous friction coefficient Ns/m
b Critical pressure ratio of gas -
gas
B Bulk modulus of oil Pa
eff
Poppet valve seat angle °
C Discharge coefficient -
d
C Sonic conductance m3/(s*Pa)
ve
d Inner diameter of restriction m
D Inner seat diameter m
i
D Poppet valve mean seat diameter m
m
D Poppet valve port diameter m
p
D Poppet valve stem diameter m
s
D Diameter for defining flow area A m
T T
D Poppet valve head diameter m
v
ε Relative uncertainly of step size -
E Energy J
E Hydraulic energy consumption J
cons
E Input hydraulic energy J
in
E Output hydraulic energy J
out
F Force N
F Coulomb friction force N
c
F Damping force N
damping
F Estimated cylinder force N
est
F Friction force N
friction
F Static friction force N
s
F Maximum retracting force N
maxR
F Minimum mode -1 force N
min1R
F Minimum mode -2 force N
min2R
ix

F Minimum extending force N
minE
F Maximum mode 1 force N
max1E
F Maximum mode 2 force N
max2E
F Force tolerance of controller N
tol
G (s) First-order transfer function -
p
G (s) Zero-order hold transfer function -
0
G(z) Z-transformed transfer function -
γ Heat capacity ratio -
h Height of inner edge m
1
h Height of outer edge m
2
I Current A
I Inertia m2*kg
x
K Coefficient of tanh friction equation -
K Specific flow coefficient of valve
v
K Flow coefficient of DFCU-AT
vAT
K Flow coefficient of DFCU-BT
vBT
K Flow coefficient of DFCU-PA
vPA
K Flow coefficient of DFCU-PB
vPB
L Length of restriction m
L Poppet valve lift m
v
Uniformity index -
m Weight kg
Mass flow kg/s
Choked mass flow kg/s

Ideal mass flow kg/s

Laminar mass flow kg/s

Real mass flow kg/s

Subcritical mass flow kg/s

Subsonic mass flow kg/s

N Number of valves -
p Circuit of circle m
c
p Upstream pressure Pa
1
p Downstream pressure Pa
2
p A-chamber pressure Pa
A
p B-chamber pressure Pa
B
p Estimated chamber pressure Pa
est
p Estimated A-chamber pressure Pa
Aest
p Estimated B-chamber pressure Pa
Best
p A-chamber pressure reference Pa
Aref
p B-chamber pressure reference Pa
Bref
p Supply pressure Pa
p
x

p Tank pressure Pa
T
p Transition pressure Pa
tr
p Minimum pressure Pa
min
p Maximum pressure Pa
max
Δp minimum pressure difference Pa
ref
Δp Nominal pressure difference Pa
nom
Pressure change -
P Power W
P Input hydraulic power W
in
P Hydraulic power loss W
loss
P Output hydraulic power W
out
Q Flow rate (Q , Q , Q , Q ) m3/s
PA AT PB BT
Q Nominal flow rate m3/s
nom
r Radius m
rpm Revolutions per minute 1/s
R Ideal gas constant J/(K·mol)
Density kg/m3

s Length of gas flow edge m
e
t Time s
t Length of impulse s
p
T Temperature K
T Temperature of air K
air
T Time constant s
c
T Temperature of methane K
methane
T Sample time s
s
T Length of constant or variable frequency s
0
u Opening of valves (uPA, uAT, uPB, uBT) -
U Voltage V
v Velocity m/s
v Velocity threshold of controller m/s
tol
v Reference velocity m/s
ref
v Reference extending velocity m/s
ref ext
v Reference retracing velocity m/s
ref ret
v Velocity of minimum friction m/s
s
v Simulated velocity m/s
sim
V Volume m3
Change of chamber volume -
x Circle of edge m
c
x Distance of curve between gas flow edges m
d
w Seat width m
W Weight of pressure differences error -
p
W Weight of valve switching -
sw