Investigation of Control System Strategies for Hydraulic Valve Actuation in an IC Engine

Transcription

1 MEM47 Automotive Project Investigation of Control System Strategies for Hydraulic Valve Actuation in an IC Engine Adil Karakayis 1 st September 2014 Supervisor: Dr Steven Begg University of Brighton School of Computing, Engineering and Mathematics, Division of Engineering & Product Design Word Count: 13259

2 Disclaimer I certify that the attached dissertation is my own work except where otherwise indicated. I have referenced my sources of information; in particular I have placed quotation marks before and after any passages that have been quoted word-for-word, and identified their origins. I give my consent that hard-copy and soft-copy of this dissertation can be made available in full for subsequent students taking this module. SIGN DATE MSc Automotive Engineering Page 1 of 93 Adil Karakayis

3 Abstract Flexible control of valve lifting, timing and duration makes possible to do significant reduction of fuel consumption and exhaust emission. Although it is possible to change valve lifting, timing and duration with camshaft based variable valve actuation systems, they have restriction of camshaft profile and no valve independency. Electro hydraulic valve actuation systems aim to optimize the restrictive camshaft profile and give independency of each valve to render possible advance internal combustion engine strategies. In this project, single electro hydraulic valve actuation system is used to investigate MATLAB based feed-forward control system. MATLAB/Simulink Simscape library components which are SimMechanics and SimHydraulics are used to simulate whole test rig because pre-calculations are necessary for the feed-forward control system. Therefore, simulation model is used to calculate a signal form for servovalve of hydraulic actuator according to engine speed and valve lift profile. At the beginning camshaft profile is followed by electro hydraulic actuator system to prove that this system has capable of existing mechanical systems. After that this camshaft profile is optimized by using basic equations of volumetric efficiency and considering air choking conditions according to piston speed. Experiments were repeated with the optimized valve lift profile. Experiments were done from 800 rpm to 6000rpm at 70bar oil pressure. Even though the experiment results are promising, if the simulation model and signal generation system is going to be improved, results might be better for feed-forward control system. MSc Automotive Engineering Page 2 of 93 Adil Karakayis

4 Table of Contents Acknowledgement... 9 Abbreviations Introduction Valve Actuation Systems Mechanical Valve Actuation System Design of Camshaft Cam Changing and Cam Phasing Systems Continuously Variable Valve Lifting Systems Electro Hydraulic Valve Actuation Systems Summary of Existing Systems Structure of Test Rig Modification of Test Rig Test Rig Equipment Oil Tank Hydraulic Pump and Electrical Motor Accumulator Oil Filter Pressure Switch Moog Servovalve Hydraulic Valve Actuator Assembly Pressure Transducer Flange Poppet Valve Control Box Main Electrical Box Oil Properties Signal Generation System Arduino Mega Function Generator Signal Amplifier Data Logging System Pressure Transducers and Charge Amplifiers Linear Variable Differential Transformer and Signal Conditioner Oscilloscope and Picoscope Test Rig Restrictions MSc Automotive Engineering Page 3 of 93 Adil Karakayis

5 3- MATLAB/Simulink Simulation Model SimMechanics SimHydraulics Hydraulic Fluid Hydraulic Pump Accumulator Way Directional Valve Optimization Tool for 4-Way Directional Valve Double-Acting Hydraulic Cylinder Control System Method of Experiments V-tec Camshaft Profile Desired Valve Lift Profile Experiment Results and Analysis Discussion of Experiment Results Future Work Conclusion References Appendix A Appendix B Appendix C MSc Automotive Engineering Page 4 of 93 Adil Karakayis

6 MSc Automotive Engineering Page 5 of 93 Adil Karakayis

7 MSc Automotive Engineering Page 6 of 93 Adil Karakayis

8 MSc Automotive Engineering Page 7 of 93 Adil Karakayis

9 MSc Automotive Engineering Page 8 of 93 Adil Karakayis

10 Acknowledgement I want to express my sincere gratitude to Dr Steven Begg who gave me that opportunity to do investigation of control system strategies for hydraulic valve actuation in an internal combustion engine. I would like to thank Mr Peter Rayner, Mr Mario Palermo and Mr Jon Armory who are SHRL technicians for their assistance to finish test rig as fast as possible. I am truly grateful to Dr Chris Garrett, Dr Daniel Coren and Dr Guillaume de Sercey for their support on this project. Finally, I thank my family for their encouragements. MSc Automotive Engineering Page 9 of 93 Adil Karakayis

11 LVDT: Linear variable differential transformer PWM: Pulse Width Modulation DAHC: Double-acting hydraulic cylinder 4WDV: 4-way directional valve IC: Internal combustion EHVA: Electro hydraulic actuation VVT: Variable valve timing Abbreviations VVTL-i: Variable Valve Timing and Lifting with Intelligence i-vtec: Intelligent Variable Valve Timing and Electronic Lift Control IVLC: Intake Valve Lift Control VVEL: Variable Valve Event and Lift MAEHV: Multi-Air Electro Hydraulic Valve Timing PID: Proportional-Integral-Derivative A : E Average effective intake flow area θ ic : Intake valve closing angle (rad) θ io : Intake valve opening angle (rad) C D: Discharger coefficient which is assumed 0.6 Z: Mean Mach number at inlet throat A p : Piston area S p: Piston mean speed c i : sound speed at inlet e v : Volumetric efficiency m i : Mass induced during valve open time ρ i : Density of air at inlet manifold V d : Displacement volume of engine ω: Engine speed (rpm) A C : Valve curtain area D v : Valve diameter L v : Lift of valve ᵧ: Heat capacity ratio which is assumed 1.4 MSc Automotive Engineering Page 10 of 93 Adil Karakayis

12 R: Ideal gas constant (287 j kgk ) T o : Air temperature at inlet manifold 300K N: Engine speed (rps) D: Displacement of the poppet valve (mm) M: Slope of LVDT sensor (mm/v) X: Sensor output voltage (V) d: Diameter of the c ylinder l: Actuator rod piston length δ: Reciprocal b: Viscous damping coefficient of hydraulic cylinder ρ: Density of hydraulic fluid v: kinematic viscosity of hydraulic fluid q: Flow rate through the orifice C d : Flow discharge coefficient A: Orifice area A max : Maximum orifice area h: Orifice opening h 0 : Initial opening of the spool h max : Maximum orifice opening x: Control member displacement (spool) P: Pressure θ C : Crankshaft angle s:piston stroke a: Crankshaft radius l:connecting rod length MSc Automotive Engineering Page 11 of 93 Adil Karakayis

13 Introduction Efficiency of conventional four-stroke IC engines are getting better while researches continuous. As new research techniques arise such as optical diagnostic techniques, it becomes possible to look at inside the combustion chamber which allows researchers to visualize swirl ratio and tumble ratio to create better air-fuel mixture. These researches illustrates and proves the importance of inlet valve operations for volumetric efficiency and exhaust valve operations for exhaust scavenging of the IC engine. As a result of increasing of emission regulations, limits of the engine efficiencies are forced. IC engines require more complex valve operation systems for better fuel economy and lower exhaust emission with the improvement of new fuel injection systems such as gasoline direct injection after port injection system. As a result of mechanically certain design of cam lobe, valve is restricted to follow that camshaft profile. Although it is possible to improve the restrictive cam profile with cam phasing and valve lifting which are integrated onto mechanical valve actuation systems, it still has restriction of the camshaft profile design. Moreover, it is required to have independence for each valve to move one step further the engine efficiencies. Freedom of valves will allow researchers to control swirl ratio better for creating homogenous mixture with highly atomized fuel. Even volumetric efficiency of IC engines can be increased by using forced induction systems such as turbocharger and supercharger, independence of valve is still required to control swirl ratio. With EHVA system, inlet and exhaust valves can be controlled by engineers with wide variety of control strategies to optimise IC engines volumetric efficiency and exhaust scavenging. It makes possible to do any kind of profile shape in the inlet and exhaust strokes. EHVA system is removed restrictions of mechanical actuation systems until the formed their own restrictions. Limitations of this system is clearly explained below. In this project, all experiments are done for the inlet valve profile which is the most important valve for IC engines. First of all, existing Vtec full lift camshaft profile for B15C7 engine is followed. Secondly, this profile is optimised for that specific engine and all experiments are done for that optimised profile also. MATLAB/Simulink is used to create a simulation model of complete system which generates a feed-forward signal for servovalve at each determined engine speed. Experiments were done for 800, 1000, 1500, 2000, 2500, 3000, 4000, 5000, 6000rpm engine MSc Automotive Engineering Page 12 of 93 Adil Karakayis

14 speeds in the pressure range of 68 to 72bar. As a result of experiments, this system has been successful up to 2500rpm at that pressure range. 1- Valve Actuation Systems Conventional IC engines have mechanically actuated valves which are controlled by a camshaft since they are designed. Even though they work very well, they have limitations for camshaft profiles which effects volumetric efficiency. This limitation is result of cam lobe design because it actuates valves in linear motion but camshaft is a rotational part. Therefore, cam lobe should have eccentric shape. Although camshaft restrictions can be improved by using cam phasing for valve overlapping and valve lifting systems, valve opening profile is still constraint by cam lobe profile. A lot of research is continuing on electromagnetic and electrohydraulic valve actuation systems which removes limitations of mechanically actuated valve systems. These systems eliminate dependency of camshaft profile and gives freedom for each valve. Therefore, they enable infinitely flexible control for valve lifting, duration and variable timing Mechanical Valve Actuation System Working principle of mechanical valve actuation system on four-stroke engine is that turning camshaft pulley by using timing belt or gear mechanism which is attached to the crankshaft pulley or gear. As the piston moves downwards in the intake stroke, crankshaft rotates, hence camshaft rotates which is attached to the crankshaft. Therefore, cam lobes pushes valves to open. While piton moves downwards, it sucks the air trough intake ports and opened intake valves. When the piston moves upwards at exhaust stroke same event happens to open exhaust valve [1]. Valves control the air/fuel or just air flow and exhaust scavenging so timing of this process has critical importance to fill the cylinder with fresh air without choking and remove the exhaust gasses efficiently. Basic mechanical valve actuation system is illustrated in the figure.1. MSc Automotive Engineering Page 13 of 93 Adil Karakayis

15 Figure.1 Mechanical valve actuation system [3] Design of Camshaft Camshaft design should be considered early design of IC engines to get optimized engine performance, fuel consumption and exhaust emission. Unique timing characteristics is necessary to have maximum engine performance with high efficiency. However, it is hard to optimise both which means while performance is at maximum, fuel consumption is high. Otherwise, when the fuel consumption is reduced, performance also reduces. When costumers purchase an automobile, they want both of them are optimised which is not possible with fixed design camshafts. In response to this problem, manufacturers have been attempting to produce variable valve timing systems such as cam phasing and valve lifting systems [2]. Typical camshaft profile is given in the figure.2. Cam lobe opening and closing ramps are designed smoothly so the valve opening and landing becomes gently. Relation of the cam lobe and valve opening profile can be seen in the figures 2 and 3. MSc Automotive Engineering Page 14 of 93 Adil Karakayis

16 Figure.2 Typical cam lobe profile [4] Figure.3 Typical camshaft profile [5] MSc Automotive Engineering Page 15 of 93 Adil Karakayis

17 Cam Changing and Cam Phasing Systems There are two types VVT systems which are valve lifting and cam phasing systems. They can be categorized to discrete and continuously systems. Cam changing and some cam phasing systems are in discrete systems. VVT systems are mostly mechanical designs. Therefore, although these systems remove the fixed valve timing and duration limitation, they have limited range to change them. Volumetric efficiency equations illustrates that VVT systems are necessarily to change valve lifting and cam phasing during engine speed increases [14]. Figure.4 Poppet valve geometry [15] θ ic A E = 1 A θ ic θ E dθ = C DA C 1 io θ io e v = A C = πd v L v 2 A p = 2πr 2 3 Z = A ps p A E c i 4 S p = 2sN 5 c i = ᵧRT 0 6 m i = 1 ρ i V d θ ic m dθ ωρ i V d θ io 7 e v = A Ec i ωv d (θ ic θ io ) ( 2 ᵧ+1 )(ᵧ+1)/2(ᵧ 1) 8 e v = 0.58 ( θ ic θ io ) 1 π z 9 MSc Automotive Engineering Page 16 of 93 Adil Karakayis

18 There is always a limiting case which flow chokes if valve lift and timing does not synchronised very well with piston speed. According to that if choked flow is the top level for the flow, volumetric efficiency can be calculated by using equation.8. These equations were used to calculate optimized profiles according to engine speed in section 4.2 for EHVA system also. With respect to equation.8, opening angle, duration time and valve lifting is affected by piston speed for the volumetric efficiency. In response to this situation, each manufacturer has VVT systems with different names and small changes. Even though they have different names, working principle is same for all of them. VVTL-i and i-vtec are examples for continuously variable cam phasing systems. All cam changing systems are discrete valve lifting systems. VarioCam and next generation VarioCam Plus are produced by Porsche Company. Volkswagen group cars are also used this system on 1.8t engines. VarioCam system does cam phasing by changing the position of tensioners with the help of hydraulic cylinder (figure.5) [6]. Figure.5 VarioCam cam phasing system [6] VarioCam Plus does cam phasing by changing cam pulley and camshaft phase angle. This event happens by forcing helical gear to move in liner motion with hydraulic pressure which changes phase angle (figure.6). VarioCam Plus has cam changing system also which enables to change valve lifting. MSc Automotive Engineering Page 17 of 93 Adil Karakayis

19 In this system, camshaft has two different cam lobe profile. One of them is for low lifting profile and the other one is for high lifting profile [7]. Figure.6 VarioCam Plus and Vanos cam phasing system [6] In the VarioCam Plus system, by changing cam lobe, two different valve profile can be followed according to engine speed (figure.7). Changing cam makes possible to switch two different cam lobes discretely which have different opening duration and valve lift. Variable hydraulic tappets are used to change these two lobes. Transition can be provided by changing the contact of lobes from inner tappet to outer tappet which can be done by locking a hydraulically actuated pin. In addition to VarioCam Plus, Vanos cam phasing system which has same working principle is used by BMW car manufacturer (figure.6). Hydraulic pressure on the piston changes the phase angle in between the cam pulley and camshaft by rotating the helical gear, when it is actuated by a solenoid valve [7]. Figure.7 VarioCam Plus cam phasing system and valve lifting mechanism [7] MSc Automotive Engineering Page 18 of 93 Adil Karakayis

20 Moreover, Toyota uses VVTL-i which is sophisticate variable valve timing system. This system is the combination of VVT-i and V-TEC. The difference of VVTL-i is just lifting mechanism. Shifting the whole camshaft phase angle is possible with VVT-i system. In this system, cam phasing mechanism is placed into the camshaft pulley which changes cam pulley and stator phase angle by just controlling hydraulic pressure. Engine oil fills into the stator oil channels and changes the phase angle with cam pulley. Honda uses i-vtec which is similar to VVTL-i system (figure.8). These two systems enable continuously cam phasing which gives flexibility to control cam phasing from low to high engine speeds [7]. Figure.8 i-vtec cam phasing system [9] Figure.9 VVTL-i valve lifting mechanism [7] MSc Automotive Engineering Page 19 of 93 Adil Karakayis

21 VVTL-i uses single rocker system similar to V-TEC mechanism with some design differences (figure.9). There are two different cam lobes as VarioCam Plus system. Difference of this system is that rocker follows lower profile at low engine speed and other lobe rotates freely. While engine speed increases hydraulically actuated pin locks the rocker arm to follow higher cam lobe. Rocker arm activation/de-activation is used by many other manufacturer also. For instance, V-TEC and GM IVLC. Although i-vtec has similar system, it has three stages cam lobes which are low, medium and high lift cam lobe profiles. Audi valve lifting system is another design for valve lifting which has two stages with three different cam lobes. Transition occurs by sliding camshaft with actuator rod and grove on the camshaft (figure.10). Mercedes Camtronic system is similar to the Audi valve lifting system [7]. Figure.10 Audi valvelift mechanism [11] Continuously Variable Valve Lifting Systems With the improvement of the VVT technology, continuously valve lifting systems have been developed such as BMW Valvetronic, Toyota Valvematic and Nissan VVEL systems. Valvetronic system is the first continuous variable valve lifting system in the world. Working principle of this system is that additional electric motor rotates eccentric shaft to push the secondary rocker arm which MSc Automotive Engineering Page 20 of 93 Adil Karakayis

22 opens valve more variably (figure.11). Therefore, valve lift displacement can be controlled continuously by just rotating eccentric shaft [7]. Figure.11 BMW Valvetronic system [7] In Toyota Valvematic system, although the design is different from BMW Valvetronic system, working principle is same. While intermediate shaft rotates to have wide angle, valve lift becomes high lift (figure.12) [7]. Figure.12 Toyota Valvematic system [7] MSc Automotive Engineering Page 21 of 93 Adil Karakayis

23 VVEL system is another design by Nissan which does same job with other continuous valve lifting systems. When control shaft rotates by electric motor because of it has eccentric shape, it pushes output cam to change the lift of valve (figure.13) [7]. Figure.13 Toyota Valvematic system [7] 1.2- Electro Hydraulic Valve Actuation Systems There are camless engines and hybrid systems which combines both systems. In the nutshell, camless engines have electrohydraulic or electromagnetic systems which have capable of all camshaft systems and more to do valve lifting and cam phasing. Although hybrid systems have semiindependence for the valves, they still have restrictions of the camshaft profile. Thus, fully EHVA systems are developed for full independency of each valve. It enables to control each valve with different profiles if it is necessary. Even though there are lots of researches on the fully EHVA systems, they are not on the production line yet. However, hybrid system such as MAEHV system which is developed by Fiat is on production cars. As it can be seen in the figure.14, this system can achieve five different strategies which are full lift, late intake valve opening, early valve closing, partial load and even multi lift. Firstly, full lift is conventional cam control which follows rigid cam profile. It is suitable for high engine speed. In second strategy, late intake valve opening is obtained MSc Automotive Engineering Page 22 of 93 Adil Karakayis

24 by electronic hydraulic solenoid valve which respects to the cam profile. This strategy is suitable for low load conditions. Early valve closing allows to anticipate the intake valve closing time which is suitable for part load operations. Fourth strategy gives possibility of closing intake valve earlier to prevent air escape to intake manifold. This strategy is done to improve acceleration at low engine speed. Final mode enables the possibility of multi valve lift in the intake stroke. This strategy is the combination of second and third strategies to regulate consumption while increase the performance at low engine speed [7]. Figure.14 Fiat Multi-Air system [7] Cam-Camless Eaton design is also hybrid system which allows to do different valve profile strategies for camless system. Possible strategies of this system are given in the figure.16 where can be seen wide variety of strategies are possible to be generated with camless system in addition to mechanical system benefits [11]. MSc Automotive Engineering Page 23 of 93 Adil Karakayis

25 Figure.15 Eaton cam-camless hybrid system [11] Figure.16 Eaton cam-camless hybrid system strategies [11] Furthermore, Ricardo Company has been developed camless HYDRA single cylinder research engine with electro-hydraulic valvetrain system which enables flexibility of continuously variable valve timing and lifting, variable opening and closing rate, multiple events, port deactivation and MSc Automotive Engineering Page 24 of 93 Adil Karakayis

26 variable valve profile [12]. Additionaly, in 2009, with the cooperation of Lotus and Eaton, active valve train system is produced which is fully VVT system with AVT actuator. Similarly, Ricardo uses this type actuator with servovalve. This system is controlled by a closed loop system. Currently, the system makes possible advance engine strategies such as homogenous charge compression ignition, without throttle operations to eliminate throttling losses, variable firing order, possible fast start, ultimately air hybridisation and differential cylinder loading [13]. Figure.17 Valve Block of Research AVT Actuator [13] 1.3- Summary of Existing Systems All mechanical systems can be applied on both inlet and exhaust camshaft. However, as it can be seen in the figure.3, although Valvetronic, Valvematic and VVEL have ability to alter valve lift infinitely according to the requirements of engine in addition to continuously variable cam phasing, valves are still restricted to follow the cam lobe profile. Unlimited flexibility is not possible for different valve strategies in mechanical systems. However, EHVA systems offer infinite variations of continuously variable and independent valve control. Which enables different strategies of valve openings, timings and profiles. With the improvement of all these variations, as it explained above, it allows engineers to develop advanced engine strategies. In next chapters, EHVA system MATLAB/Simulink based feed-forward control strategy is tested to enable all these advance engine strategies. MSc Automotive Engineering Page 25 of 93 Adil Karakayis

27 2- Structure of Test Rig Figure.18 Diagram of the complete setup MSc Automotive Engineering Page 26 of 93 Adil Karakayis

28 Electro hydraulic valve actuation test rig was designed to do all determined experiments for generating desired valve profile. In this test rig, hydraulic pump is controlled by a control box for oil pressure supply. This oil pressure is kept constant by an on/off closed loop control system which is controlled by a pressure switch. Moreover, all data are saved by a picoscope. Furthermore, complete test rig is simulated into a MATLAB/Simulink model to create signal form for a servovalve. This simulated signal form for the servovalve is generated by a function generator when it is triggered by a triggering button to control the poppet valve. In brief, the simulation model enables feed-forward control system for the EHVA system. Because of the simulation is used, all specifications about the test rig equipment should be known to enter all necessarily parameters for simulation model. Required equipment and their specifications are explained below Modification of Test Rig EHVA test rig was already existing but it was modified according to needs for new experiments. First of all, test rig was designed to be more rigid. EHVA assembly and oil filter bracket was designed to be more robust. This bracket allows to change oil filter easily, if it is necessary. Protective clear polycarbonate sheet and its frame was designed to protect the operator from any leakage or frangible parts. All leakages were fixed and sink was designed to catch oil leakage of the hydraulic actuator which is completely normal. This leakage keeps away dust particle from the actuator. Test rig was designed to become all connections with solid pipes. However, although pipes are ordered, they did not arrive at the expected time. Therefore, flexible pipes are used which were already available. Detailed Solidworks drawings for new designed parts are given in the appendix A. Desired designed test rig appearance is like that; MSc Automotive Engineering Page 27 of 93 Adil Karakayis

29 Figure.19 Back view of the test rig design [24] Figure.20 Front view of the test rig design [24] MSc Automotive Engineering Page 28 of 93 Adil Karakayis

30 Figure.21 Front view of the test rig design [24] 2.2- Test Rig Equipment These equipment which are listed below are all required for actuation of a poppet valve and data logging system. All necessarily specifications are given for the simulation model. Figure.22 Equipment of test rig control system MSc Automotive Engineering Page 29 of 93 Adil Karakayis

31 Figure.23 Back view of test rig equipment Figure.24 Top view of test rig equipment MSc Automotive Engineering Page 30 of 93 Adil Karakayis

32 Item Description Quantity 1 Oil tank x1 2 Hydra micro pack hydraulic pump x1 3 Electrical motor x1 4 Parker Olaer accumulator x1 5 Fox pressure switch x1 6 Parker high pressure oil filter x1 7 Moog servovalve x1 8 Kistler pressure transducer x1 9 Pressure transducer flange x1 10 Helipebs hydraulic valve actuator x1 11 Poppet valve x1 12 Control box x1 13 Main electrical box x1 14 Fuse box x1 15 TTi TG1010A function generator x1 16 Custom signal amplifier x1 17 Linear variable differential transformer x1 18 Microstrain signal conditioner x1 19 Kistler pressure charge amplifier x2 20 Tektronix TDS 220 oscilloscope x1 21 National instrument picoscope x1 22 Computer x1 23 Protective clear polycarbonate and frame x1 24 Oil filter & EHVA assembly bracket x1 25 High pressure flexible hydraulic pipes x1 26 Ball valve x1 27 Pressure gauge x1 Table.1 List of test rig equipment Oil Tank 4.5 litre aluminium oil tank is used such as a secondary tank. When oil decreases in actual oil reservoir of the hydraulic pump because of the leakage at hydraulic actuator, ball valve is opened to fill it Hydraulic Pump and Electrical Motor Hydraulic oil pressure source of the test rig is Hydra Products micro pack hydraulic pump. This micro pack includes XV-0P/0.25 group fixed displacement gear pump. Mounting of the hydraulic pump assembly should be horizontal because gear pump type is in tank and the filler position is at the side of the pimp. Moreover, air breather position is at top. Additionally, it has pressure relief MSc Automotive Engineering Page 31 of 93 Adil Karakayis

33 valve. When this valve is activated, it relieves all pressure in the system. Assembly includes 0.5 litre plastic oil tank which can be filled by secondary oil tank. After it is filled ball valve should be closed. Otherwise, all oil in the secondary tank comes out from the air breather. This pump which has 0.24cm 3 /rev size has the capable of 260bar maximum pressure in the speed range of 700 to 9000rpm. According to the selection of the electric motor which is AC motor 250 Watt 240V 50Hz S2 duty in this project, moto-pump performance is given in the graph.17 in appendix A. The pressure range is in between 10 to maximum 120 bar. Volumetric efficiency is in the range of 0.91 to 0.96, mechanical efficiency is 0.85 to 0.90, recommended oil is mineral oil and working temperature range is in between -15 to 70 C [16] [17] Accumulator Parker Olaer diaphragm accumulator which has the capacity of 0.16litre is used on the test rig to stabilize the oil pressure in the system. It is pre-charged with nitrogen which gives maximum 130bar pressure load [18] Oil Filter Any tiny dust particles can block servovalve or may affect the performance. Therefore, Parker hydraulic filter is used on the test rig to filter out these particles. Although the size of the filter elements are 10µm, pressure is not affected a lot. Pressure differential is 0.2 bar at l/min flow rate which is maximum flow rate of the servovalve. Therefore, it is not considered into the simulation model. It can be seen in the graph.18 in appendix A. [20] Pressure Switch Fox F4 adjustable pressure switch is used on the test rig to control pressure in the system. Switch is set to remain the system at determined pressure. It can be adjusted by rotating the screw with 2 mm hexagonal key manually. This pressure switch is used for closed loop on/off control system. Working principle is that when the oil pressure force is more than spring force which is adjusted by the screw, needle opens the electric circuit. For this reason, main electric box cannot send any electric signal to MSc Automotive Engineering Page 32 of 93 Adil Karakayis

34 the electric motor until pressure drop. While pressure drops, pressure switch closes electric circuit and send electric signal back to the electric motor to increase the oil pressure [19]. Figure.25 Diagram of Pressure switch [19] Moog Servovalve Servovalve controls the flow rate for the hydraulic actuator according to electrical current signal. It can be divided to three main parts which are torque motor, hydraulic amplifier and valve spool. Operation procedure is such that electrical current signal creates magnetic forces on the armature which creates torque according to the current value in the range of +/- 50 ma. This torque rotates the flapper to close or reduce the opening area of the one end of the nozzle while opens or increases the opening area of the other end. It changes the flow balance in the hydraulic amplifier. Changed flow goes to return line through drain orifice which creates imbalance hydraulic force on the spool. Because of that, the spool moves to one direction. When the spool moves one direction, it opens pressure port on that direction which allows main oil flow to the hydraulic actuator. On the other hand, it opens return port for the other end of the hydraulic actuator at the same time. Additionally, MSc Automotive Engineering Page 33 of 93 Adil Karakayis

35 spool movement generates some force on the feedback spring which helps torque armature and flapper to return its original position immediately after current signal becomes 0 value [23]. Moog series 31 servovalve specifications are given in the table.2 Flow datasheet characteristics are given in the graph.19 in appendix A. Figure.26 Diagram of the servovalve [23] System Pressure 280 bar (4000 Psi) Rated Flow 15.0 l/min +/- 10% at 70 bar Maximum Leakage 1.95 l/min Rated Signal +/ ma Response Type High Fluid Mineral oil Seals N90D Body Type 31 Series Connector Type Bendix Screws Std Additional Comments 10% P-C2 Table.2 Moog servovalve specifications [22] Hydraulic Valve Actuator Assembly Helipebs hydraulic valve actuator is the main part of the test rig which provides movement of the poppet valve according to the controlled oil flow. Working principle is very basic which oil fills the MSc Automotive Engineering Page 34 of 93 Adil Karakayis

36 piston area in order to provide linear movement of the poppet valve. Poppet valve is attached on the one end of actuator rod. Other end is used for LVDT sensor. There is no piston ring for sealing but piston has four groves which are for lubrication of the piston to reduce the friction of the rod. However, it creates small damping force. Therefore, viscous damping coefficient should be calculated for the simulation by these equations; k δ = d δ k l = l d b = π. ρ. v. k δ. k l. d 12 Figure.27 Sectional view of the actuator rod piston and cylinder [35] According to the equations, damping coefficient is equal to 1.6N.s/m. Where; ρ: kg/m 3 at 27C v: cst ( m 2 /s) at 27C d: 11.00mm δ: 0.50mm l: 22.00mm MSc Automotive Engineering Page 35 of 93 Adil Karakayis

37 Because of there is no sealing on the piston and heads, leakage occurs. In order to prevent leakage at ports of servovalve and flange, O-rings are used in between pressure transducer flange and servovalve. Ports should be exactly matched to avoid any dislocation of ports, when parts are assembled. Therefore, dowels are used for each parts. Exploded view of the hydraulic actuator assembly is illustrated in the figure.28 Figure.28 Exploded view of hydraulic valve assembly [24] # Description 1 LVDT sensor 2 Top head of actuator 3 Pressure inlet for actuator 4 Return 5 Pressure line for servovalve 6 Return line 7 Kistler pressure transducers 8 Bolt for transducer 9 Pressure transducer flange 10 Moog type31 servovalve 11 Hydraulic actuator rod 12 Bottom head 13 Poppet valve Table.3 Hydraulic valve assembly parts Hydraulic actuator has complex geometry at two ends which improves end damping of actuator rod. It is showed in the figure.29. MSc Automotive Engineering Page 36 of 93 Adil Karakayis

38 Figure.29 Sectional view of hydraulic valve assembly [24] Heads have some tolerance in between the cylinder. Head diameter is mm and cylinder diameter is 11.0 mm. In theory, oil passes through this tolerance to reach cavity for improving end damping. Moreover, heads have groove to allow oil flow when the rod is at very end. For end damping, V 1 and V 2 should be considered into the SimHydraulics double-acting hydraulic cylinder block so they were calculated by using Solidworks drawings. V 1 is 20.25mm 3 and V 2 is mm Pressure Transducer Flange Pressure transducer flange is assembled in between servovalve and actuator for measuring the pressure differential of two pressure lines. This location is selected for pressure transducers because of technical issues such as hardness of actuator body material. Although it is possible to drill with carbide drill bit, it is too hard for tapping. Therefore, flange is made which is the easiest way to attach pressure transducers on the pressure lines. By this method, dynamic of the fluid is affected as little as possible. MSc Automotive Engineering Page 37 of 93 Adil Karakayis

39 Figure.30 Hydraulic valve actuator and pressure transducer flange body [24] Poppet Valve # Description 1 Top pressure line 2 Bottom pressure line 3 Kistler bottom pressure transducer 4 Pressure transducer bolt 5 Pressure inlet for actuator 6 Pressure line for servovalve 7 Top pressure line 8 Bottom pressure line Table.4 Pressure lines and measurement equipment Conventional poppet valve is used for this project which has 36 mm diameter and 45 mm length Control Box Control box has three functions which are data logging, communication to main electrical box and signal triggering. Control box has high quality 0.1 microfarad capacitor for triggering cable ground connection to avoid triggering the function generator without trigger signal because of electric motor high current jump. Additionally, it has emergency button if anything goes wrong which activates the pressure relief valve of hydraulic pump to relieve pressure in the system. Schematic drawing of the control box is given in the figure.52 in appendix. A. MSc Automotive Engineering Page 38 of 93 Adil Karakayis

40 Main Electrical Box Main electrical box controls hydraulic pump according to signal of control box. Feedback control system with on/off controller is used to control oil pressure into the system. Pressure switch is used as an on/off switch. The main electrical box schematic drawing is given in figure.53 in appendix. A. Figure.31 Block diagram of pressure control system 2.3- Oil Properties Mobil Super W 40 fully synthetic engine oil is used in this project because IC engines already use this oil. Although this system can work with hydraulic oil which will give better performance. It is important to know the performance of the EHVA system with standard engine oil to reduce the cost of complete system on IC engines. Less components mean low cost. Typical properties of 10W 40 Mobil Super 2000 oil is given in the table.5 SAE Grade 10W 40 Viscosity ASTM D44S CSt at 40 C 70 CSt at 100 C 10.8 Sulfated Ash, ASTM D874 (wt%) 0.96 Pour Point, ASTM D97 (C ) -30 Flash Point, ASTM D92 (C ) 226 Density at 15.6 C, ASTM D4052 (g/ml) 0.87 Table.5 Mobil Super T oil properties [28] 2.4- Signal Generation System Although the signal is calculated by the MATLAB/Simulink model, computer requires an interface to generate analog signal for the servovalve. Firstly, Arduino Mega 2560 electronic board is used to generate that signal. Even though it generates the signal successfully, modulation frequency which MSc Automotive Engineering Page 39 of 93 Adil Karakayis

41 is 488 Hz is not enough to generate same signal form in valve opening time interval above 500 rpm. Therefore, TTi TG1010A function generator is used which has higher frequency Arduino Mega 2560 As it is explained, MATLAB/Simulink model is used in this project to generate feed-forward signal so interface should be able to communicate with MATLAB software. Arduino has able to do this communication but it can generate just digital or PWM signal output. However, analog output is required for signal amplifier to convert it current signal. Therefore, PWM signal is converted to the analog signal by using low-pass filter which increases clock timing. Specifications of Arduino Mega 2560 is given in the table.6 [29]. Operation Voltage 5V Input Voltage 7-12V Input Voltage Limits 6-20V Digital I/O Pins 54 (14 of them PWM) Analog Input Pins 16 DC Current per I/O Pin 40mA DC Current for 3.3V Pin 50mA SRAM 8KB EEPROM 4KB Flash Memory 256KB (8KB used for Bootloader) Clock Speed 16MHz Table.6 Mobil Super T oil properties [29] PWM signal can be explained such as a duty cycle in the figure.32. The Arduino can generate 0-5v which is equal to in PWM. Therefore, Arduino generates 0 voltage when the signal is 0 and constant 5 volt when the signal value is 255. However, any value in between these two values creates duty cycle percentages in the PWM signal form. Therefore, by using low-pass filter, average of this duty cycle can be converted to analog voltage output. Low-pass filter schematic drawing is given in the figure.33. By changing the resistor or capacitor value response time which means frequency of each period for the PWM signal can be changed. Response time is equal to multiplication of resistor and capacitor value. Firstly, 10kohm resistor is tried. After that 4.7kohm and then 1kohm resistors with 1microfarad capacitor. Which gives us respectively 0.01s, s and s for the period time interval [30]. Additionally, sample rate of simulated signal into the MATLAB/Simulink model MSc Automotive Engineering Page 40 of 93 Adil Karakayis

42 should be above this period time interval to be able to download it into the Arduino. These signals which are just example are given in the graph.1 Figure.32 Pulse Width Modulation [30] Figure.33 Schematic drawing of the low-pass filter [30] First of all, signal into the MATLAB/Simulink model should have offset value because PWM cannot generate negative values. Therefore, signal which is calculated into the model should be multiplied by and summed with offset value to generate the signal in the range of The plan was generating the signal in the range of 0-5v. When the signal became below the offset value which is 2.75v, negative value would be generated by custom designed signal amplifier. In other case, signal would be positive. MSc Automotive Engineering Page 41 of 93 Adil Karakayis

43 Figure.34 PWM form of MATLAB/Simulink servovalve signal [31] Because of the limited memory of Arduino (256 KB) all model cannot be downloaded into the Arduino so signal is saved to workspace of MATLAB for exporting it excel file. After that, it is imported to signal builder into another model which is created for Arduino to download it into the Arduino. Figure.35 PWM conversion of MATLAB/Simulink servovalve signal for Arduino [31] Graph.1 Comparison of response times a:1, b:4.7 and c:10kohm [32] MSc Automotive Engineering Page 42 of 93 Adil Karakayis

44 Although, the signal form could be catch with 1kohm resistor and 1 microfarad capacitor low-pass filter, it cannot be used to be connected to signal amplifier because there is too much noise. As a solution of this problem function generator is used Function Generator TTi TG1010A function generator is used to generate analog voltage for the simulated signal. Simulated signal is saved in comma separated value form to be able to download it into the function generator. RS-232 to USB adaptor is required for the connection of the function generator and computer. Schematic drawing is given in the figure.36. Although the function generator can generate downloaded signal form with high resolution (1023x1023), every time, frequency of function generator should be adjusted very carefully to get same time interval of the signal with simulated signal into the model. Signal can be controlled by an oscilloscope while frequency is adjusted. Because of that, problem occurs. It is not easy to generate exactly same signal with the model. Thus, some error occurs for the duration of valve opening. Figure.36 Diagram of the RS-232 to USB adaptor [33] MSc Automotive Engineering Page 43 of 93 Adil Karakayis

45 Repetition for signal form can be set to repeat signal as much as wanted. However, according to the setup of test rig, triggering signal which comes from picoscope is required to activate triggering mode of the function generator to do desired repetition. That triggering signal controls beginning of data saving for picoscope also. Therefore, signal for servovalve and data saving is triggered at the same time Signal Amplifier Generated signal by the function generator is sent to signal amplifier to convert the voltage signal to current signal form for the servovalve. There is a scale factor for current monitoring because signal amplifier has10k ohm resistance in between the current monitoring and actual current signal which goes to servovalve. Moreover, 1V is equal to 1A for current monitoring of signal amplifier for saved data. Therefore, when measurements are illustrated in voltage such as 500 mv means 50 ma for current monitoring in data analysis section. Schematic drawings of the custom designed signal amplifier is given in the appendix. A Data Logging System National instruments NI USB-6008 picoscope is used to save data in numerical form and Tektronix TDS220 oscilloscope is used to illustrate real-time data for data logging of the test rig. Pressure transducer s signals are saved by the picoscope to determine the pressure differential of both inlet of hydraulic actuator. For determining the displacement of the poppet valve, LVDT sensor signal is saved. Finally, both function generator voltage and signal amplifier current signal monitoring are saved by the picoscope to determine signal amplifier performance and signal which goes to servovalve Pressure Transducers and Charge Amplifiers Kistler piezoelectric sensors and charge amplifiers are used to measure pressure as it explained in the section of These pressure sensors are generally used to measure brake mean effective pressure of IC engines but it works onto this system very well. Scale factor is 20 bar/v for both charge amplifiers [34]. MSc Automotive Engineering Page 44 of 93 Adil Karakayis

46 LVDT Sensore (V) Linear Variable Differential Transformer and Signal Conditioner 2 LVDT Sensor Calibration Valve Displacement (mm) Graph.2 Calibration of the LVDT sensor Microstrain LVDT sensor is used to measure the poppet valve displacement. LVDT sensor is connected to the microstrain signal conditioner. Additionally, the signal conditioner is connected to the picoscope to save the movement of the valve. This sensor is frictionless which means that it does not affect the movement of the poppet valve. It is required to do calibration to know the values in each mm movement. However, these values are reliable if the LVDT sensor does not remove or replace. Slope is mm/v. Therefore, according to voltage output of the LVDT sensor, displacement can be calculated by equation.13. D = M x X Oscilloscope and Picoscope Tektronix TDS220 oscilloscope is used to demonstrate real-time data for adjusting function generator signal frequency. Additionally, LabVIEW Signal Express software is used to save data in numerical form with picoscope. Configuration of the software is set to save data when it is triggered. Trigger MSc Automotive Engineering Page 45 of 93 Adil Karakayis

47 source is on the picoscope channels where triggering switch is connected to PFIO to +5v channel with an on/off switch. In the configuration, digital rising edge is selected to begin data saving. Moreover, this triggering signal triggers the function generator also. All data is saved in voltage form and scale factors are used to convert them in pressure, displacement and current form during analysing. 5 analog channels are used on the 8 channel (10kHz) picoscope which are signal input voltage after function generator, signal current monitoring after signal amplifier, two pressure transducers and LVDT sensor output. Therefore, sampling rate for 5 channels becomes 2 khz (0.0005s). The voltage range of measurements is +/- 10v [26] Test Rig Restrictions Test rig has some restrictions because of high pressure oil so pressure endurances of each equipment are given in the table.7. Equipment Maximum Pressure (bar) Parker oil Filter 414 Parker Olaer accumulator 210 Fox F4 Pressure switch 70 Hydra Products Hydraulic Pump 120 Moog servovalve 280 Flexible hydraulic hoses 220 Table.7 Test rig pressure restrictions [17] [18] [19] [20] [21] MSc Automotive Engineering Page 46 of 93 Adil Karakayis

48 3- MATLAB/Simulink Simulation Model Figure.37 MATLAB/Simulink model [31] MSc Automotive Engineering Page 47 of 93 Adil Karakayis

49 Whole test rig is simulated by created MATLAB/Simulink model according to the real parameters of the hydraulic components. Some realistic assumptions were done which are explained below. Physical modelling components of Simscape such as SimMechanics and SimHydaulics were used to create the simulation model of EHVA system. SimMechanics and SimHydraulics uses physical connections so actual EHVA system matches with the simulation model as much as possible. Subsystems for SimHydraulics and SimMechanics were used to make the model more tidy [36] [37]. Figure.38 Simulation model [45] 3.1- SimMechanics SimMechanics are used to simulate physical properties of the poppet valve and hydraulic actuator such as mass of the poppet valve and actuator rod. In addition to mass, viscous damping coefficient of hydraulic piston which is calculated in the hydraulic valve actuator section is considered in the model also. It can be entered by using the function of internal mechanics. Blocks are representing bodies, joints, constraints and force elements. For example, Hydraulic_Valve_Assembly_1_RIGID represents the constraints. Poppet_valve_with_hydraulic_rod_1_RIGID represents the moving part in linear motion and cylindrical block represents cylindrical joint [38]. Figure.39 illustrates the SimMechanics components of hydraulic actuator. MSc Automotive Engineering Page 48 of 93 Adil Karakayis

50 Figure.39 SimMechanics simulation model [31] Cylindrical joint is the most important part in the SimMechanics because it determines displacement, velocity and acceleration of the poppet valve. In addition to them, physical connection of the poppet valve actuation is provided by this block. As it can be seen in the figure.39 ideal force sensor is connected to that physical line to calculate the force which acts on the poppet valve by hydraulic cylinder. Moreover, ideal transitional velocity source is used to do the connection in between SimMechanics and SimHydraulics. The reason of using this sensor is that sensing the movement of the double acting hydraulic cylinder and converting it to force. After that, this force is applied to the cylindrical joint to calculate the poppet valve velocity according to its weight and internal mechanics. Finally, determined velocity is connected to the ideal transitional velocity source again for relative velocity [41]. These sensors do not affect the connected physical line such as inertia, friction, delays and energy consumption so they are called ideal sensors [39]. PS-Simulink Converters are used to convert Simulink input signal to physical signal. Units of the output can be changed by using these blocks [40]. These blocks were attached to scopes for illustrating solutions. The easiest way to implement hydraulic valve actuator, actuator rod and poppet valve into the SimMechanics which was drawn into the Solidworks is SimMechanics Link into the Solidworks. There are two generations for MSc Automotive Engineering Page 49 of 93 Adil Karakayis

51 SimMechanics but second generation SimMechanics is used into this modelling which has less blocks and more functions [38]. Additionally, SimMechanics can illustrate the movement of these parts in 3D environment. Figure.40 SimMechanics [31] [38] 3.2- SimHydraulics SimHydraulics are used to simulate electric motor, hydraulic pump, accumulator, servovalve and hydraulic actuator. Ideal angular velocity source, fixed-displacement hydraulic pump, gas-charged accumulator, 4-way directional valve and double acting hydraulic cylinder components of SimHydraulics are used to represent them respectively. PS-Simulink Converters are used for same purpose. Hydraulic flow rate sensors were connected in between the DAHC and 4WDV to calculate the flow rate according to opening signal of 4WDV [43] [46]. MSc Automotive Engineering Page 50 of 93 Adil Karakayis

52 Figure.41 SimHydraulics simulation model flow control [31] Figure.42 SimHydraulics simulation model of power unit [31] In the actual test rig, pump is rotated by the electric motor but in the simulation, pump is controlled by an ideal angular velocity source. Therefore, pressure can be easily controlled by increasing or decreasing the angular velocity of the pump [42]. There is a difference between actual test rig and simulation model in this situation but it does not affect the signal which is simulated for the MSc Automotive Engineering Page 51 of 93 Adil Karakayis

53 servovalve. The difference is that pump is not rotated continuously in the actual test rig because it has control system to stop electric motor when it reaches the expected pressure. However, pump rotates incessantly in the simulation to keep the pressure constant. Finally, hydraulic pressure sensor is used to calculate the pressure in the simulation Hydraulic Fluid Hydraulic fluid block was used to set oil properties which are explained in the chapter.2. Because 10W 40 oil is used hydraulic fluid was selected 10W in the block parameters. Relative amount of trapped air was entered which is an assumption. System temperature was selected 27C which is the room temperature because there is no heat source to heat the oil except pressurized oil itself and electric motor. Therefore, experiments were repeated while the electric motor and oil cool down to room temperature. Viscosity derating factor was entered As a result of these values, hydraulic fluid block calculated the density, viscosity and bult modulus respectively kg/m 3, cst and e 9. These calculations are matched with real parameters Hydraulic Pump All hydraulic pump parameters which are explained in the chapter.2 are required for the fixeddisplacement hydraulic pump block. Pump displacement was entered 24e 7 m 3 /rev. Volumetric and mechanical efficiencies were entered 0.92 and Finally, nominal pressure, angular velocity and kinematic viscosity were entered respectively 120bar, 314rad/s and m 2 /s Accumulator Accumulator parameters are such that capacity is 0.16litre, pre-load pressure is 130bar, initial volume 0m 3, specific heat ratio is 1.4 and structural compliance is 1e 13 m 3 /Pa. Last two parameters are assumptions Way Directional Valve This component simulates the most important part of whole system which is Moog servovalve. Normally, the servovalve system is more complex than a 4WDV but all required parameters have not been known so it is simplified by using 4WDV. Although it is simplified, it does its job as good MSc Automotive Engineering Page 52 of 93 Adil Karakayis

54 as possible. The principle of 4WDV is that the signal is connected to the signal port which controls the spool movement. Movement of the spool is scaled in the range of 0-100% for one direction which means for fully opening, it will be 100% and for fully closing, it will be 0%. Spool can move both direction so the range becomes -100 to 100%. According to rated input signal, spool opens port A or B as determined area [47]. Opening areas are given in the table.8 Figure.43 4-way directional valve block [44] The spool opening areas which is given in the table.8 are calculated by optimization tool for 4-way directional valve according to Moog series 31 servovalve flow datasheet characteristics. Flow data sheet is given in the appendix A. In the MATLAB/Simulink model, 4WDV has 100% efficiency for spool movement so it can open instantaneously. However, actual servovalve cannot do this because it has torque motor delay, hydraulic amplifier delay and spool inertia. Therefore, if rapid opening is required which is showed in the figure.44, transfer function should be applied into the model just before 4WDV signal to simulate phase lag. Generally, it is required for exact square valve profile. For other cases, simulation model is good enough. Signal change can be seen in the figure.44 by using transfer function. MSc Automotive Engineering Page 53 of 93 Adil Karakayis

55 Figure.44 Moog servovalve transfer function effect [31] Moog servovalve transfer function is given by the manufacturer such that; Figure.45 Moog servovalve transfer function [49] MSc Automotive Engineering Page 54 of 93 Adil Karakayis

56 During the calculation of Moog series 31 servovalve phase lag, sine wave was used so frequency is from peak to peak [49]. Therefore, period interval should be calculated in between opening and closing signals. First order transfer function is good enough up to 1500rpm. Above that engine speed, second order transfer function should be used up to 300Hz. However, transfer function was not use in the simulation model because of the factors which are explained with more details in the optimized valve lift profile section. For valve lifting profile, there is not any square shape Optimization Tool for 4-Way Directional Valve This optimization tool is created by Mathwork engineers to tune the 4WDV opening areas according to Moog series 31 servovalve flow datasheet characteristics by using optimization algorithms. Figure.46 Optimization Tool for 4-Way Directional Valve [48] This MATLAB optimization tool uses these equations with iteration system to calculate valve opening areas for required flow rate. q = C d. A 2 P sign(p) 14 P A = A max h max h 15 h PA = h PA,0 + x 16 MSc Automotive Engineering Page 55 of 93 Adil Karakayis

57 h PB = h PB,0 + x 17 h AT = h AT,0 + x 18 h BT = h BT,0 + x 19 There is an assumption which is h PA = h PB = h AT = h BT = 0 because it is not known if the servovalve spool has initial opening. There are another assumptions which are 1x10 9 mm 2 leakage area and 0.2mm 2 maximum spool opening area for the optimization tool. By entering flow rate parameters of Moog servovalve and pressure drop in bar, opening areas can be calculated. In table.8 flow rates are given according to rated movement of the spool. Breakpoints Actual Servovalve current (ma) Vector Output Values (mm) Flow Rate (lpm) Opening Areas (mm 2 ) Table.8 Flow datasheet characteristics of series 31 Moog servovalve [23] Double-Acting Hydraulic Cylinder Double-acting hydraulic cylinder component is used for simulating the hydraulic actuator. As it mentioned in chapter.2 and as it can be seen in the figure.27, viscous damping coefficient parameters were entered via SimMechanics cylindrical joint internal mechanics so the model does not have additional dumping component. The block parameters are given in table.9. Piston Area A (m 2 ) Piston Area B (m 2 ) Piston Stroke (m) Dead Volume A (m 3 ) Dead Volume B (m 3 ) Specific Heat ratio 1.4 Contact Stiffness (N/m) 100 Contact Damping (N.s/m) 1.5 MSc Automotive Engineering Page 56 of 93 Adil Karakayis

58 Chamber A Initial Pressure (bar) 70 Chamber B Initial Pressure (bar) 70 Table.9 Double-acting hydraulic cylinder block parameters 3.3- Control System Feed-forward control system is used for the test rig which has some benefits such as LVDT sensor does not required which means less cost. For this project, LVDT sensor was assembled to illustrate actual movement of the poppet valve. Although feed-forward control systems is used for actual servovalve signal (figure.18), feedback control system is used to simulate the signal in the simulation model for the feed-forward control system. As it explained in chapter.2, simulation is used to simulate the movement of the poppet valve according to desired profile. Accordingly, required flow rate is calculated for the movement to open valve (spool) of 4WDV. In summary, Feedback control system is used to calculate the signal for opening of the spool according to required flow rate. After that, simulated signal is used such as feed-forward signal for actual servovalve. Figure.47 Block diagram of the simulation feedback control system Figure.48 Block diagram of feed-forward control system of the test rig MSc Automotive Engineering Page 57 of 93 Adil Karakayis

59 Error occurs in between desired position and actual position of the poppet valve in the simulation. Therefore, all parameters were entered as real as possible to simulate the actual EHVA system error for generating realistic feed-forward signal. PID controller is used to fix that error. Even though just proportional part was used for experiments, integral and derivative parts also can be used to improve correction of the error. Working principle is such that desired profile is sent to 4WDV by using signal builder, this signal is subtracted from actual position of the poppet valve which is 0 at the beginning. Therefore, error becomes highest value at that point which is multiplied by determined proportional value. This value becomes 4WDV opening signal. According to that signal, it sends calculated amount of oil flow to DAHC. Poppet valve moves up to the amount of DAHC movement and this position is sent back to be subtracted from desired profile signal. While error reduces, opening signal of the 4WDV changes. This signal is saved to download into the function generator to become feedforward signal for the desired profile. However, signal should be inverted while it is downloaded into the function generator because of the signal amplifier terminal connections. 4- Method of Experiments Experiments were done for 800, 1000, 1500, 2000, 2500, 3000, 4000, 5000 and 6000rpm engine speeds for both valve lift profiles. First of all, V-tec camshaft profile which is for B15C2 Honda engine was tried to be followed. After that, this profile was improved for that specific engine by using the flexibility of EHVA system. These profiles were imported into the simulation model by using signal builder block of MATLAB/Simulink. Afterwards, 4WDV input signals which are saved by Simout block were downloaded into the function generator after they were inverted. Frequencies of these signals were adjusted to have same time interval with the simulated signals. Offset values were adjusted to close the valve fully and balance the hydraulic amplifier of the servovalve. Downloaded signals were sent to the signal amplifier by triggering to allow the signal amplifier changes them from voltage to current form. Subsequently, current signal was sent to the Moog servovalve in order to provide movement of the actual poppet valve. The movement was saved by picoscope via LVDT sensor. During these processes, pressure on both inlets of hydraulic actuator were saved by picoscope via pressure transducers to analyse dynamics of hydraulic actuator MSc Automotive Engineering Page 58 of 93 Adil Karakayis

60 behaviour. All these processes are explained with more details in chapter.2. Operation procedure is given in the table.10 # Description 1 Run simulation in MATLAB/Simulink model 2 Save signal data in Sigdata.csv file format 3 Download it into TTi TG1010A function generator 4 Check all sensors and actuator connections 5 Check all pipe connections 6 Turn on main switch on main electrical switch 7 Press on button to run hydraulic pump which is on control box 8 Adjust pressure switch to 70bar 9 Adjust offset value for servovalve 10 Run picoscope software 11 Press triggering button which is on control box 12 Collect data and save them 13 Press off button to stop hydraulic pump which is on control box. It will release all pressure in the system 14 Press emergency button to relief all pressure into the system if anything goes wrong Table.10 Operation procedure of the test rig Experiment Engine Speed (rpm) Proportional Gain Frequency (Hz) DC Offset (mv) Amplitude (Vpp) (Peak-Peak) Table.11 Function generator and Simulink model parameters for V-tec camshaft profile Experiment Engine Speed (rpm) Proportional Gain Frequency (Hz) DC Offset (mv) Amplitude (Vpp) (Peak-Peak) Table.12 Function generator and Simulink model parameters for optimized profile MSc Automotive Engineering Page 59 of 93 Adil Karakayis

61 Valve Lift [mm] Valve Velocity [mm/degree] 4.1- V-tec Camshaft Profile V-tec full lift camshaft profile was used to be followed to prove that the EHVA system have ability to produce existing profiles. Camshaft profile is given in the graph Cam Angle [degrees] Exhaust Valve Lift Primary Valve Lift Secondary Valve Lift VTEC Valve Lift Exhaust Valve Velocity Primary Valve Velocity Graph.3 V-tec camshaft profile [51] As it can be seen in the graph.3, camshaft profile is given in crankshaft angles but signal builder into the simulation model cannot accept degrees so these equations are used to calculate time interval per one crankshaft angle. θ C. ( 1 rpm/60 ) / Opening durations of valve profiles for 210CA V-tec camshaft and desired valve lift according to engine speeds are given in the table.13. Engine Speed (rpm) V-tec Profile Opening Duration (ms) Optimized Profile Opening Duration (ms) Table.13 Opening duration of 210CA camshaft and 180CA desired profiles MSc Automotive Engineering Page 60 of 93 Adil Karakayis

62 4.2- Desired Valve Lift Profile EHVA systems which eliminate dependency of the restrictive camshaft profile and give freedom for each valves allow infinitely controls for valve lifting, duration and variable timing. Therefore, V-tec camshaft profile was optimized with the flexibility of EHVA system. Although this system has ability to provide almost square valve profile. There are some limitations for IC engine volumetric efficiency in addition to mechanical limitations such as valve failure under high speed opening and closing conditions [14] [52] [53]. For this reason, during the optimization of valve opening profile for B15C2 engine volumetric efficiency and valve opening and closing velocities are considered too. B15C2 engine required parameters are given in the table.14 to calculate valve opening profile without air choking condition. Moreover, valve full lifting should be at maximum piston speed. Accordingly, volumetric efficiency was calculated as high as possible by considering piston speed and air choking during the calculation of valve lifting profiles. Although it is required to do more complex calculations and experiments to determine the best profile for an engine, equation.1, 2, 3, 4, 5, 6, 7 and 8 are used for calculation of valve lifting profiles for opening. Unlike opening profiles, just valve speed was considered for closing profiles because opening duration time should be as much as possible for letting air breathing more. However, it cannot have square profile because of the speed factor so it is calculated to limit speed of the valve as little as possible without losing area. Finally, the equation for 180CA opening profile becomes such that; s = a. sin(θ C ) + (l 2 a 2 sin 2 (θ C )) 1/2 21 L v = S p = ds dt A p.s p (0.676.C i.π.c D D v )x Where; A p : m 2 S p : Changes with the engine speed C i : m/s MSc Automotive Engineering Page 61 of 93 Adil Karakayis

63 C D : It is assumed 0.6 D v : 0.036m Bore B (mm) Figure.49 IC engine geometry for piston speed calculation [54] Connecting Rod Length l (mm) Table.14 Honda B15C2 engine specifications [55] Crankshaft Radius a (mm) Although all profiles are given in the experiment result section, an opening profile is given in the graph.4 to illustrate one of the desired profile shape. The difference in between opening profile and closing profile can be seen in the graph.4. Moreover, while engine speed increases, opening profile changes because of the relation of piston speed and valve lifting profile. After 2500rpm, due to speed MSc Automotive Engineering Page 62 of 93 Adil Karakayis

64 Lift (mm) Velocity (m/s) factor, same opening profile with 2500rpm was used for above engine speeds. On the other hand, closing profile is fixed for every engine speeds. Desired Profile (1000rpm) Time (s) Desired Lift (mm) Desired Velocity (m/s) Graph.4 Desired valve profile for 1000rpm 5- Experiment Results and Analysis 18 experiments were done for each engine speed and both profiles. Therefore, it is not possible to illustrate every experiment results in this report. Thus, major points are explained in this section. Other experiment results and analysis are given in the attached CD at the back of the dissertation. Although experiment s target pressure is 70bar, all experiments were done in the pressure range of 68 to 72bar for both V-tec and optimized valve profiles. Because of the pressure switch low response, control system is unable to maintain the constant pressure. Minimum error was caught at 800 and 1000rpm so every explanations of analysis will be at these engine speeds. Moreover, explanation of reasons for increasing error of the other engine speeds are given in this section also. Additionally, time interval in each 5 crank angle becomes approximately but picoscope can record with dt: (2kHz). Therefore, some points are missed in data logging after 2000rpm. For example, it can MSc Automotive Engineering Page 63 of 93 Adil Karakayis

65 Lift (mm) - Engine speed x1000(rpm) be seen clearly for optimized profile input signal at 5000 and 6000rpm. First of all, V-tec camshaft profile comparison is given to illustrate the error of the actual valve lift according to varying engine speed from 800 to 6000rpm. Although EHVA system has the capable of lifting profile repetitions, each experiment is done separately because just one signal form can be downloaded into the function generator. However, they are combined to show them together in a graph. Repetition experiments analysis are given in the CD. 12 Valve Lift Time (s) Desired Lift (mm) Engine Speed x1000 (rpm) LVDT(mm) Simulation Lift (mm) Graph.5 Comparison of desired, simulation and actual valve lift for V-tec lift profile Duration of the signal is adjusted by adjusting function generator frequency. It is explained in chapter.2 with more details. Therefore, one of the reason of these errors for valve opening durations are because of human error in addition to simulation error. Errors are acceptable up to 2000rpm but after that engine speed valve lifting begins to lose which is directly related about pressure. By increasing the pressure, it can be solved but leakage of the actuator will also increase so without doing experiment with higher pressure it is hard to predict that. Valve speed comparisons are given in the graph.6. MSc Automotive Engineering Page 64 of 93 Adil Karakayis

66 Engine Speed (x1000rpm) Amplitude (V) Engine Speed (x1000rpm) Velocity (m/s) 7 6 Valve Speed Time (s) Engine Speed x1000 (rpm) Desired Velocity (m/s) Actual Velocity (m/s) Graph.6 Comparison of desired and actual valve speeds for V-tec lift profile Even though speed of the valve is almost matched with desired speed up to 1000rpm after that engine speed, valve could not move fast enough to catch desired profile so speed of the actual valve movement is less than desired valve speed. Signal of function generator and after signal amplifier which is called current monitoring is given in the graph Input Signal Time (s) Engine Speed x1000 (rpm) Current Monitoring (A) Input Signal (v) Graph.7 Input signals for V-tec lift profile (500mV=50mA) MSc Automotive Engineering Page 65 of 93 Adil Karakayis

67 Lift (mm) Signal (x0.1a) As it can be seen in the signal analysing, oil flow rate is related by time and servovalve spool opening. Therefore, the spool should be opened more to get same oil flow rate in shorter time interval to supply more oil into the hydraulic cylinder. Furthermore, there is an offset value for the moog servovalve. While amplitude increases offset value changes also in the function generator but output voltage is almost same. DC offset value of the function generator is very important because servovalve spool does not close ports at the beginning. In theory, it might happen because servovalve spool has initial openings with ports or internal leakages of the spool. The other reason might be that the spool does not stop, it always moves one direction excessive slowly while DC offset is given. Therefore, DC offset should be adjusted very carefully to close ports. Otherwise, offset value may affect by ignoring or reducing opening or closing signal. It depends which way is selected. As it explained above, it is assumed to move very slowly to one direction. Therefore, in these experiments, DC offset value is selected to close valve fully which means spool direction is selected to move one direction excessive slowly to open one port to allow oil flow for pushing valve to be fully close. After that, signal is sent to servovalve. Value of DC offset is selected very low to do not affect the signal and can be different a little bit for function generator when same experiment is repeated. However, it is same for output of function generator according to the graph.7. For example, DC offset value may change + and - 5 mv. Table of function generator parameters are given in chapter V-tec Camshaft Profile vs Signal (at 1000rpm) Time (s) LVDT(mm) Desired Lift (mm) LVDT(mm) Simulation (mm) Current Monitoring (A) Graph.8 Comparison of the valve lifting for V-tec lift profile at 1000rpm MSc Automotive Engineering Page 66 of 93 Adil Karakayis

68 Lift (mm) Pressure (Bar) Lift (mm) Velocity (m/s) 12 Valve Speed (at 1000rpm) Time (s) LVDT(mm) Desired Lift (mm) Actual Velocity (m/s) Desired Velocity (m/s) Graph.9 Valve speed for V-tec lift profile at 1000rpm Pressure (at 1000rpm) Time (s) LVDT(mm) Bottom Pressure (bar) Top Pressure (bar) Graph.10 Pressure of the hydraulic actuator inlets according to V-tec lift profile at 1000rpm Although actual valve lifting error is low at 1000rpm which is the lowest error for V-tec profile, valve closes too fast. It should be improved to avoid valve failure. Hydraulic actuator both sides pressure are given in the graph.10. Dynamic behaviour can be understood from these pressure measurements. They are used to improve simulation model by comparing them with the calculated pressure into the simulation model. For instance, because of the Moog servovalve spool internal geometry is not known, opening areas of the 4WDV were assumed according to optimized tool of MSc Automotive Engineering Page 67 of 93 Adil Karakayis

69 Lift (mm) - Engine Speed (x1000rpm) MATLAB. However, these areas are modified to get similar pressure graph into the simulation model. Pressure measurements demonstrate pressure differential of both inlets. Pressure drop can be seen for both inlets at valve opening and closing times. Pressure graphs are very similar because the profile is same for valve opening and closing. However, they are not same for optimized profile which is illustrated in the graph.16. Secondly, Optimized valve lifting profile comparison is given to show actual valve lifting error for varying engine speed from 800 to 6000rpm. Lowest error is at 800rpm for optimized profile experiments. Although displacement of the hydraulic actuation is 11.8mm, desired poppet valve lift is maximum 10mm to prove that valve does not fluctuate at full lift opening duration. Similar to camshaft profile experiments, valve lifting begins to lose after 1000rpm. 12 Valve Lift Time (s) Desired Lift (mm) Simulation Lift (mm) LVDT(mm) Engine Speed x1000 (rpm) Graph.11 Comparison of desired, simulation and actual valve lift for optimized lift profile Valve speed is given in the graph.12 which demonstrates error increases as engine speed increase because valve lift profile does not follow desired lift profile as expected. MSc Automotive Engineering Page 68 of 93 Adil Karakayis

70 Engine Speed (x1000rpm) Amplitude (V) Engine Speed (x100rpm) Velocity (m/s) Valve Speed Time (s) Engine Speed x1000 (rpm) Desired Velocity (m/s) Actual Velocity (m/s) Graph.12 Comparison of desired and actual valve speeds for optimized lift profile Input Signal Time (s) Engine Speed x1000 (rpm) Current Monitoring (A) Input Signal (v) Graph.13 Input signals for optimized lift profile (500mV=50mA) Valve opening and closing profiles have differences as it mentioned before. Therefore, signals for opening and closing are different also as demonstrated in graph.13. When engine speed increases, both profiles becomes similar so signal also becomes similar. However, after 2000rpm data logging MSc Automotive Engineering Page 69 of 93 Adil Karakayis

71 Lift (mm) Velocity (m/s) Lift (mm) Signal (x0.1a) system sample rate does not enough to save each 5CA. It can be seen easily on 5000 and 6000rpm input signals. 10 Optimized Profile vs Signal ( at 800rpm) Time (s) -0.4 Simulation (mm) LVDT(mm) Desired Lift (mm) Current Monitoring (A) Graph.14 Comparison of the valve lifting for optimized lift profile at 800rpm Valve Speed (at 800rpm) Time (s) Desired Lift (mm) LVDT(mm) Desired Velocity (m/s) Actual Velocity (m/s) Graph.15 Valve speed for V-tec lift profile at 1000rpm MSc Automotive Engineering Page 70 of 93 Adil Karakayis

72 Lift (mm) Pressure (Bar) 10 9 Pressure (at 800rpm) Time (s) LVDT(mm) Bottom Pressure (bar) Top Pressure (bar) -40 Graph.16 Pressure of the hydraulic actuator inlets according to optimized lift profile at 800rpm Same problem with V-tec lift profile occurs in this profile also. Valve closes very quickly which might cause valve failure. Pressure graph of the optimized valve lift profile is used to modify MATLAB/Simulink model to adopt it actual test rig Discussion of Experiment Results Although simulation model is used to create signal form of the desired valve lift profile, signal form is distorted partially while it is downloaded into the function generator. Moreover, signal is changed partly by signal amplifier also. Furthermore, it changes a little when the frequency is adjusted because of human error. For these reasons, error becomes more than it should be. Thus, besides simulation model, signal generation system is also required to improve. As it expected, valve lifting profile error increased while engine speed increased. The pressure should be increased to fix that error because flow rate does not enough to fill hydraulic actuator instantaneously in 2500rpm and above engine speed's time intervals. If pressure switch is replaced, test rig pressure endurance changes which means EHVA system pressure can be increased up to 120bar. This increment may reduce that error. MSc Automotive Engineering Page 71 of 93 Adil Karakayis

73 6- Future Work This setup which was created to do experiments works quite well but transitions of signals for different engine speeds takes time. Therefore, although this system can be applied for real engine, it is not possible to do experiments for different engine speeds at once. Which means that if the setup is configured for 1000rpm, engine speed should be exactly 1000rpm. It can be done by making a one tooth trigger wheel which is connected to the cranks shaft. This system will enables to know piston position to triggering the function generator for the signal and picoscope at the same time instead of manually triggering. This experiment can be repeated for different engine speeds. However, there is a solution for that problem which is XPC target or similar interfaces. By using XPC target, it is possible to change the setup to do experiments with real-time controls. This is called hardware in the loop system [56]. Additionally, this system enables to measure the pressure into the EHVA system to change the parameters into the simulation model. Because of the simulation model is sensitive to pressure changes, it will change the 4WDV control signal. Possible pressure sensing model is demonstrated in the figure.50 Figure.50 SimHydraulics actual pressure measurement for power unit [31] Moreover, it will enable to change the controller parameters in real-time. Besides all these improvements, it is required to change the 100% 4WDV block by advanced servovalve model which MSc Automotive Engineering Page 72 of 93 Adil Karakayis

74 is provided by MATLAB/Simulink [8]. This replacement will be improved the simulation model to generate more realistic signal to become more compatible with the real test rig. However, it is necessary to know all internal dimensions and specifications to enter them into the advanced servovalve model. This model has simulations blocks of flapper/armature for torque motor, flapper/nozzle for hydraulic amplifier and main valve for the spool. Figure.51 SimHydraulics advance servovalve model [31] Finally, in addition to these improvements feedback control system might be added to feed-forward control system to reduce the error. It might work better than just feedback or feed-forward control system because feed-forward will reduce the huge error for feed-back control system. Therefore, possible collision of the poppet valve and piston wil be avoided. MSc Automotive Engineering Page 73 of 93 Adil Karakayis

75 Conclusion This project is about the investigation of control system strategies for hydraulic valve actuation in an IC engine. This investigation makes possible to increase flexibility of control of valve lifting profile, timing, and duration. Which might reduce significant amount of fuel consumption and exhaust emission by using advanced engine strategies. In this project, feed-forward control system is used to control EHVA system which is required pre-calculation to determine the signal form of servovalve to manage hydraulic actuator. Therefore, MATLAB/Simulink Simscape physical modelling components are used such as SimMechanics and SimHydaulics to simulate required signal form for EHVA system. First of all, existing camshaft profile was followed to prove that the EHVA systems have capable of existing technologies. Secondly, this profile is optimized to illustrate that this systems can remove the restrictions of camshaft profiles and VVA systems. Although experiments were done from 800 to 6000rpm, utilizable profile forms are just up to However, in my opinion, this engine speed is good enough to do experiments of advance engine strategies on research engines. Even though 18 experiments were done, it does not possible to insert each experiment analysis in this report. Therefore, major points are explained in this report and other analysis of experiment are insert into the CD which is attached at the back of the report. MATLAB/Simulink model files, solidworks drawings, valve lift profiles, function generator signals, test rig equipment specifications and interim report are inserted into the CD also. MSc Automotive Engineering Page 74 of 93 Adil Karakayis

76 References [1] Grey, J. A., Electronic-Valve-Actuation-in-Combustion-Engine-libre. BSc. University of Queensland. Available at: < [Accessed on 12 August 2014] [2] Brader, S. J., Development of a Piezoelectric Controlled Hydraulic Actuator for a Camless Engine. BSc. University of Boston. Available at: < [Accessed on 10 July 2014] [3] Cam belt, The engine how the valves open and close. [Image online] Available at: < [Accessed on 12 August 2014] [4] Cam lobe, Cam lobe design. [Image online] Available at: < [Accessed on 12 August 2014] [5] Camshaft profile, Compcams overlap. [Image online] Available at: < [Accessed on 12 August 2014] [6] VarioCam, VarioCam cam phasing system. [Image online] Available at: < [Accessed on 13 August 2014] [7] Cam-changing and Cam-phasing, Variable Valve Timing. [Image online] Available at: < [Accessed on 13 August 2014] [8] MathWorks, Inc Hydraulic System with Servo-Valve. [Online] Available at: < > [Accessed on 07 June 2014] [9] Cam phasing system, Intelligent -Variable Valve Timing and Lift Electronic Control. [Image online] Available at: < [Accessed on 13 August 2014] [10] Audi valvelift, Audi Variable Valvelift System in Detail [Image online] Available at: < [Accessed on 13 August 2014] [11] McCharty, J. and Stretch, D Compact, electro-hydraulic, variable valve actuation system providing variable lift, timing and duration to enable high efficiency engine combustion control. In: US Department of Energy, High-Efficiency Engine Technologies. Dearborn, 18 October US: Eaton Corporation. MSc Automotive Engineering Page 75 of 93 Adil Karakayis

77 [12] Hall, G., n.d. Ricardo Advanced Research Engines Single cylinders. [Online pdf] Shorehamby-Sea: Ricardo UK Ltd. Available at: < [Accessed on 10 July 2014] [13] J.W.G. Turner and S.A. Kenchington Lotus Engineering, Production AVT Development: Lotus and Eaton's Electrohydraulic Closed-Loop Fully Variable Valve Train System. [Online pdf]. USA: Eaton Automotive. Available at: < [Accessed on 12 August 2014] [14] Haq, M.Z., Volumetric Efficiency of Engines, ME 401: Internal Combustion Engine. [Online] Bangladesh University of Engineering & Technology. Available at: < [Accessed on on 27 July 2014] [15] RGM Racing, n.d. Flow through valves, valve geometry. [Image online] Available at: < [Accessed on 26 July 2014] [16] Vivolo, Vivolo introduction datasheet [Online pdf] Italy: Sole Shareholder Company. Available through: Vivoil company website: [Accessed on 28 May 2014] [17] Hydra Products, n.d. Hydra Products micro pack hydraulic pump [Online pdf] UK: Hydra Products Company. Available through: Hydra products company website: < [Accessed on 20 June 2014] [18] Parker Hanifin, Parker Oaler diaphragm accumulator [Online pdf] UK: Parker Hanifin Corporation. Available through: Parker company website: < %20Europe/Accumulators_Paris_English/Diaphragm%20Accumulators,%20ELM%20from%2014 0%20to%20350%20bar,%20EMDC.%20HY UK.pdf> [Accessed on 27 June 2014] [19] Sor Inc., Pressure switch operating principles [Video online] Available at: < [Accessed on 11 June 2014] [20] RS, n.d. Parker hydraulic filter specifications [Online] UK: RS Component Ltd. Available at: < _source=applegate.co.uk> [Accessed on 27 June 2014] [21] SSFlex, Flexible hydraulic hoses [Online] China: Huaxing Rubber Hose Co Ltd. Available at: < [Accessed on 15 August 2014] [22] Moog servovalve, Using the Ricardo laboratories. [Moog valve specification] May Brighton: University of Brighton MSc Automotive Engineering Page 76 of 93 Adil Karakayis

78 [23] Moog, n.d. Type 30 nozzle-flapper flow control servovalves [Online pdf] USA: Corporate Headquarters - Moog Inc. Available at: < [Accessed on 28 May 2014] [24] Solid solutions supporting excellence, Solidworks(x64) [Computer program] Solid solutions management ltd. Available at: < Price.aspx> [Accessed on 30 May 2014] [25] Informer technologies, Proteus 7 [Computer program] Labcenter electronics. Available at: < [17 August 2014] [26] National Instrument, NI USB-6008 picoscope [Online] UK: National Instruments Corporation Ltd. Available at: < [Accessed on 18 August 2014] [27] Papathanasiou, D Investigation of the performance characteristics of an Electrohydraulic valve for automotive applications. BEng. University of Brighton. [28] Mobil, High performance four-stroke motorcycle engine oil product description [Online] Australia: Exxon Mobil Corporation. Available at: < English/Lubes/PDS/GLXXENPVLMOMobil_Super_4T.aspx> [Accessed on 30 May 2014] [29] Ebay Inc ATmega2560 Mega AU Board (Arduino-compatible) [online] Available at: < 497.l2649> [Accessed on 13 June 2014] [30] Daniels, S Arduino s AnalogWrite Converting PWM to a Voltage [Online] Available at: < [Accessed on 18 June 2014] [31] MathWorks, Inc MATLAB 2013a. [Computer program] Available at: < [Accessed on 19 May 2014] [32] National Instruments Corporation, LabVIEW [Computer program] Available at: < [Accessed on 30 June 2014] [33] Thurlby Thandar Instruments, TTi TG1010A manual [Online] UK: Thurlby Thandar Instruments Ltd. Available at: < enerator_instruction_manual.pdf> [Accessed on 30 June 2014] [34] KISTLER, &6123 pressure transducer specifications [Online] USA: Kistler Holding AG. Available at: < [Accessed on 18 August 2014] [35] Koreisová, G., Identification of viscous damping coefficient of hydraulic motors [online pdf] Scientific Papers of the University of Pardubice. Available at: MSc Automotive Engineering Page 77 of 93 Adil Karakayis

79 < scous_sp%20dfjp_2006.pdf> [Accessed on 14 July 2014] [36] MathWorks, Inc MATLAB 2013a SimMechanics Link. [Computer program] Available at: < irmation_page&wfsid= > [Accessed on 22 May 2014] [37] Patel, C Creating and Masking Subsystems, Simulink. [Video online] Availible at: < [Accessed on 20 May 2014] [38] MathWorks, Inc MATLAB 2013a SimMechanics. [Computer program] Available at: < [Accessed on 20 May 2014] [39] MathWorks, Inc Ideal Force Sensor. [Online] Available at: < [Accessed on 22 May 2014] [40] MathWorks, Inc Simulink-PS Converter. [Online] Available at: < [Accessed on 22 May 2014] [41] MathWorks, Inc Ideal Translational Velocity Source. [Online] Available at: < [Accessed on 22 May 2014] [42] MathWorks, Inc Ideal Angular Velocity Source. [Online] Available at: < [Accessed on 22 May 2014] [43] MathWorks, Inc MATLAB 2013a SimHydraulics. [Computer program] Available at: < [Accessed on 27 May 2014] [44] Miller, S Modeling a Custom Hydraulic Valve, Simulink. [Video online] Availible at: < [Accessed on 27 May 2014] [45] Miller, S Modeling a Hydraulic Actuation System, Simulink. [Video online] Availible at: < [Accessed on 27 May 2014] [46] MathWorks, Inc Creating and Simulating a Simple Hydraulic Model. [Online] Available at: < [Accessed on 27 May 2014] [47] MathWorks, Inc Way Directional Valve. [Online] Available at: < [Accessed on 27 May 2014] MSc Automotive Engineering Page 78 of 93 Adil Karakayis

80 [48] Miller, S Hydraulic Valve Parameters from Data Sheets and Measured Data, Simulink. [Video online] Availible at: < from-data-sheets-and-measured-data html?form_seq=conf966&confirmation_page&wfsid= > [Accessed on 28 May 2014] [49] Thayer, W.J., n.d. Transfer Functions for MOOG Servovalves [Online pdf] EU: Moog Inc. Available at: < [Accessed on 16 July 2014] [50] Douglas, B., PID Control System. [Video online] Available at: < [Accessed 9 May 2014] [51] B15C2 Camshaft Profile, n.d. [Image online] Available at: < [Accessed on 21 July 2014] [52] Kumar, G.U. and Namilla, V.R Failure Analysis of Internal Combustion Engine Valves by Using ANSYS. [Online pdf] India: AIJRSTEM. Available at: < [Accessed on 29 June 2014] [53] Azadi, M., Roozban, M. and Mafi, A Failure Analysis of an Intake Valve in a Gasoline Engine. [Online pdf] Iran: Iran Society of Engine. Available at: < [Accessed on 29 June 2014] [54] Ciccarelli, G Engine Performance, MECH 435: Internal Combustion Engines. Queen s University. Available at: < [Accessed on 27 July 2014] [55] Tripod. n.d. Honda Engine Specs. [Online] Available at: < [Accessed on 27 July 2014] [56] Denery, T. and Mirsky, S Hardware-in-the-Loop (HIL) Testing of a Position Control System, Simulink. [Video online] Available at: < [Accessed on 27 May 2014] MSc Automotive Engineering Page 79 of 93 Adil Karakayis

81 Appendix A Graph.17 Motor-pump performance [17] Graph.18 Parker 10µm oil filter pressure-flow characteristics [20] MSc Automotive Engineering Page 80 of 93 Adil Karakayis

82 Graph.19 Moog series 31 servovalve flow datasheet characteristics [23] MSc Automotive Engineering Page 81 of 93 Adil Karakayis

83 Figure.52 Schematic of Control box [25] [27] MSc Automotive Engineering Page 82 of 93 Adil Karakayis

84 Figure.53 Schematic of main electrical box [25] [27] MSc Automotive Engineering Page 83 of 93 Adil Karakayis

85 Figure.54 Schematic of signal amplifier [25] [27] MSc Automotive Engineering Page 84 of 93 Adil Karakayis

86 All drawings are in mm. Figure.55 Solidworks drawing of pipes t-connection bracket [24] MSc Automotive Engineering Page 85 of 93 Adil Karakayis

87 Figure.56 Solidworks drawing of HVA and oil filter bracket.a [24] MSc Automotive Engineering Page 86 of 93 Adil Karakayis

88 Figure.57 Solidworks drawing of HVA and oil filter bracket.b [24] MSc Automotive Engineering Page 87 of 93 Adil Karakayis

89 Figure.58 Solidworks drawing of Pprotective glass frame [24] MSc Automotive Engineering Page 88 of 93 Adil Karakayis

90 Figure.59 Solidworks drawing of sink [24] MSc Automotive Engineering Page 89 of 93 Adil Karakayis

91 Figure.60 Solidworks drawing of pressure transducer flange [24] MSc Automotive Engineering Page 90 of 93 Adil Karakayis

92 Appendix B MSc Automotive Engineering Page 91 of 93 Adil Karakayis

93 Appendix C Figure.61 Plan of the project MSc Automotive Engineering Page 92 of 93 Adil Karakayis