Major Project Report on Design and Control of an Electromechanical Actuator for Variable Valve Timing for Partial fulfilment to award of Bachelor of Technology in Automobile Engineering Submitted by Aditya Jindal (2K10/AE/25) Pankaj Kandpal (2k10/AE/40) Mohit Yadav (2K10/AE/37) Rahul Khurana (2K10/AE/48) Under the supervision of Dr. R.C. Singh DEPARTMENT OF AUTOMOBILE ENGINEERING DELHI TECHNOLOGICAL UNIVERSITY DELHI-110042 2014 Major Project Report on Design and Control of an Electromechanical Actuator for Variable Valve Timing for Partial fulfilment to award of Bachelor of Technology in Automobile Engineering Submitted by Aditya Jindal (2K10/AE/25) Pankaj Kandpal (2k10/AE/40) Mohit Yadav (2K10/AE/37) Rahul Khurana(2K10/AE/48) Under the supervision of Dr. R.C. Singh DEPARTMENT OF AUTOMOBILE ENGINEERING DELHI TECHNOLOGICAL UNIVERSITY DELHI-110042 2014

DECLARATION We hereby declare that the major project report entitled “Design and Control of an Electromechanical Actuator for Variable Valve Timing” submitted to Delhi Technological University is a record of original work done by us under the guidance of Dr. R.C. Singh, Department of Mechanical Engineering. It is further declared that this project work has not been submitted for the award of any other degree or diploma.

Aditya Jindal (2K10/AE/25) Mohit Yadav (2K10/AE/37) Pankaj Kandpal (2K10/AE/40) Rahul Khurana (2K10/AE/48)

CERTIFICATE BY SUPERVISOR

This is to certify that the major project report entitled “Design and Control of an Electromechanical Actuator for Variable Valve Timing” is authentic work performed by Aditya Jindal, Mohit Yadav, Pankaj Kandpal and Rahul Khurana for the requirement to the partial fulfilment of Bachelor of Technology (Automobile Engineering) at Delhi Technological University. This work has been completed under my supervision and guidance and has not been submitted for the award of diploma or degree from any other institute or university. Dr. R. C. Singh Department of Mechanical Engineering

ACKNOWLEDGEMENT

I owe a great many thanks to a great many people who helped and guided me during this project. I owe my profound gratitude to our project guide, professor, Dr. R.C. Singh , who took keen interest on our project work and guided us all along till the completion by providing all the necessary information for the development of a good system. I have immense pleasure in expressing my thanks and gratitude to Prof. Naveen Kumar, Head of the Department, Delhi Technological University for his guidance and encouragement. I am thankful and fortunate enough to get constant encouragement and timely support and guidance from all teaching and non-teaching staff which helped us to successfully complete our project. ABSTRACT Camless engine provide various advantages over the conventional internal combustion engine but realisation of it has been a problem for the industry. Variable valve timing achieved through it improves the efficiency, fuel economy and lessens the emissions of car. Many efforts have been put to realise it through various methods like mechanical, hydraulic, electromechanical and electrical actuators. Below is such an effort to control the timing of the valve by using electro mechanical principles. The model presented uses mechanical links along with an electronic circuit. The objective is to make the motion as flexible as possible.

List of figures

Sno. Figures Page No. 1. Electromechanical actuator…….……………….....7 2. Block diagram……………………….………….....9 3. Solenoid coil……………………….........….….....11 4. Valve opening and closing……………….……....14 5. Cad drawing of model..…………….…….............15 6. Model 2………………………………..….……...17 7. Cylinder head………………………………….…22 8. Solenoid and connecting linkage………….….…..23 9. Batteries…..……………………………................24 10. Connecting link…………..……………….............25 11. Model.………….………………..……………….29

CONTENT : 1. Declaration………………………………….…………….II 2. Certificate…………………………………………………..III 3. Acknowledgement……………………………..…………IV 4. Abstract…………………………….………………………..V 5. List of figures……………………………….……………………..VI 6. Chapter 1: Introduction 7.1 Introduction………………..……………………………….8 7.2 History of camless engine…………………………….…………………………9 7.3 Camless mechanism………………………………..….....................11 7.4 Literature review…………………………………………………..….13 7. Chapter 2: Modelling and Analysis 8.5 Initial concept…………………………………………………..…15 8.6 Calculation………………………………….........................17 8. Chapter 3 : Experimental setup 9.7 Components……………………………………………...19 9.8 Fabrication ………………………………………………………………………..20 9.9 Previous model …………………………………………………………………26 9.10 Current model…………………………………………………………………..27 9. Chapter 4: Conclusion ……………………………………………………….28 10. References…………………………………………………………….............29

Chapter 1 INTRODUCTION

1.1 CONVENTIONAL VALVETRAIN CONTROLLED BY CAMSHAFT Since the invention of internal combustion engine, the control of motion of valves is done through cams. Internal combustion engines have been using camshaft and poppet valve for intake and exhaust. The cam has been an integral part of the IC engine since its invention. The cam controls the “breathing channels” of the IC engines, that is, the valves through which the fuel air mixture (in SI engines) or air (in CI engines) is supplied and exhaust driven out. Besieged by demands for better fuel economy, more power, and less pollution, motor engineers around the world are pursuing a radical “camless” design that promises to deliver the internal combustion engine’s biggest efficiency improvement in years. In the conventional cam mechanism, the lift and closing of valves is fixed by the profile of the cam lobe in the engine. Hence, less air is taken in during intake and less exhaust is thrown out during the exhaust process. The cam is linked to camshaft through various mechanical linkages. This restrains the flexibility of the cam to shift according to the different speed. This has lead to low torque output, more engine emission due to incomplete combustion which eventually leads to the lower fuel economy. Human desire for perfectionism has led to improvement in the efficiency of engine but there is not much scope left. Mechanical engineers have constantly researched changes in design and other mechanisms in order to propose various methods in order to attain maximum efficiency. Various methods and designs proposed in the past like SOHC (single overhead camshaft), DOHC (double overhead camshaft), spring less valve, air valve and many more. Among these, the VTEC technology gained immense popularity through the Honda engines and hence prompted researchers to plunge into the field of Variable Valve Timing (VVT). 1.2 BASIC CONCEPT OF VARIABLE VALVE TIMING

Variable Valve Timing (VVT) is basically a process of altering the timing of the valve lift and valve closing events and is often used to improve performance fuel economy and efficiency. Due to difference between engine conditions at lower and higher RPMs, there are different optimum valve timings for different RPMs. Variable valve timing is aimed at optimizing the valve timing with respect to conditions at a particular range of RPM in order to achieve higher fuel efficiency, higher power output and lower emissions as opposed to the conventional use of constant valve timing at all RPMs. There are many ways in which this can be achieved. Hydraulic and electro-mechanical systems have been used to develop different versions of VVT. Moreover, introduction of VVT has been an added advantage to the automotive manufacturers as emission regulation has become stricter these days. During initial steps of variable valve timing, either discrete form or continuous form was used. In discrete form, the division was done on basis of an rpm above or below which the timing was made variable. In the continuous the RPM was varied continuously over time. VVT offers change in cam profile during the engine operation eventually leading to higher power, less emissions and higher fuel efficiency. Valve events are controlled separately and are independent of the crankshaft rotations. As a result of this fuel consumption is reduced to 15 % and CO2 emission reduced to 15% on an average. The first few players to introduce VVT technology in market were Japanese automakers like Mazda and Honda. Honda improved their fuel efficiency by up to 10% through use of their VTEC (variable timing electronic control) technology. The principle of operation was that there were two cam lobes one for low rpm and fuel efficiency and other for high rpm rate output. The switching operation between these was controlled by an electronic control unit (ECU). This type of system leads to complexity and there was less space for improvement in torque. Although most of the problem was solved yet there was room to make this timing variable infinitely. So the concept of controlling valve motion by mechanical, hydraulic and electromechanical actuator came into the existence during 20th century. 1.3 INTRODUCTION TO CAMLESS MECHANISMS FOR VALVE ACTUATION To eliminate the cam, various mechanisms have been proposed which are given as follows: 1. Hydraulic: In this hydraulic force is used in order to push the valve stem and this can be varied flexibly according to the need of user the mechanism use piezoelectric stack as an important component. This was proposed by university of South Carolina. 2. Electrical: In this the electrical forces and magnetic forces are used in order to bring the required flexibility in the mechanism. This is the most common mechanism in the Camless engine.

The mechanism used by us is not electrical and hydraulic but an amalgamation of mechanical and electronic principles. Hence it is an electro-mechanical mechanism

In camless valve actuation mechanism the vital components are sensors and electronic control unit. The sensor will send signal to the electronic control unit which comprises of the microprocessor. The microprocessor is programmed accordingly with a software algorithm. This sends the required signal to the actuator. The current is sent to the actuator in form of this signal.

Engineers have developed different mechanisms for camless valve actuation. These can be broadly divided into electro-hydraulic and electro-mechanical mechanisms. The electro-hydraulic actuation system is the most reputable and durable one. The electro-hydraulic system was developed by the Ford motor company in year 1994 and was later improved and redesigned by the Lotus Company. The basic electro hydraulic system contains two pressure sources, one spring return single acting actuator and two solenoid valves. The first solenoid actuated spool valve (HPSV) is located between the high pressure hydraulic source and the engine valve actuator and is responsible for controlling the submission of the high pressure oil into the actuator during engine valve opening interval. The second solenoid valve (LPSV) is located between the engine valve actuator and the low-pressure hydraulic source and is responsible for evacuating the actuator during engine valve closing stage. In this type of camless valve train, the engine valve timings and duration can be adjusted by Controlling the opening and closing timings of the two hydraulic solenoid valves. But the second mechanism which employs an electro-mechanical actuator has been found to have maximum efficiency (Figure 1). Principally, it is a mass spring oscillating system along with a magnetic subsystem causing variable valve timing through use of voltage and coils (Wang et al 2000). It consists of coils, a clapper and a spring. The duration of intake and exhaust can be made very flexible and independent through use of this mechanism (sugimoto et al 2004). This also suffered high energy consumption due to fact that when the turnkey is switched off the clapper was left in neutral position so whenever engine is started the first catching by upper coil had to be energised. Also the problem due to the seating velocity was quite prominent in this. Other studies were done in order to improve this mechanism (okada et al 2004, kim et al 2005; kim 2005; tsu chai 2003).

Figure 1.1: Electromechanical Actuator[ref no.]
In the electro-mechanical actuator, a magnetic field is generated by a magnetic field generator and is directed across the fixed air gap. An armature having a current-carrying armature coil is exposed to the magnetic field in the air gap. When current is passed through the armature coil and that current is perpendicular to the magnetic field, a force is exerted on the armature. When a current runs through the armature coil, perpendicular to the magnetic field, an electromagnetic vector force, known as Lorentz force, is exerted on the armature coil. The force generated on the armature coil drives the armature coil linearly in the air gap in a direction parallel with the valve stem. Depending on the direction of the current supplied to the armature coil, the valve will be driven toward an open or closed position. These latest electromechanical valve actuators develop higher and better-controlled forces than those designs mentioned previously. These forces are constant along the distance of travel of the armature because the size of the air gap does not change.
In this project we have used a solenoid coil to perform the function of armature coil. Solenoid is the generic term for a coil of wire used as an electromagnet. It also refers to any device that converts electrical energy to magnetic energy using a coil. The device creates a magnetic field from electric current and uses the magnetic field to create linear motion. Common applications of solenoids are to power a switch, like the starter in an automobile, or a valve, such as in a sprinkler system.

A solenoid is a coil of wire in a corkscrew shape wrapped around a piston, often made of iron. As in all electromagnets, a magnetic field is created when an electric current passes through the wire. Electromagnets have an advantage over permanent magnets in that they can be switched on and off by the application or removal of the electric current, which is what makes them useful as switches and valves and allows them to be entirely automated.

Like all magnets, the magnetic field of an activated solenoid has positive and negative poles that will attract or repel material sensitive to magnets. In a solenoid, the electromagnetic field causes the armature to either move backward or forward, which is how motion is created by a solenoid coil. In a direct-acting valve, electric current activates the solenoid, which in turn pulls a piston or plunger that would otherwise block air or fluid from flowing. In some solenoid valves, the electromagnetic field does not act directly to open the conduit. In pilot-operated valves, a solenoid moves the plunger, which creates a small opening, and pressure through the opening is what operates the valve seal. In both types, solenoid valves require a constant flow of electrical current to remain open because once the current is stopped, the electromagnetic field disperses and the valve returns to its original closed position.

1.4 OBJECTIVE OF THE PROJECT: The main objective of this project is to “design and control a electromechanical actuator in order to obtain variable valve timing”. The problems encountered during this vary from the control problems to the seating and vibration problems due to turdy nature of the electromechanical actuator. The problem of the camless valve trains have been discussed as earlier. The project was divided into many segments so that the objective could be achieved in minimum time. The segments were divided as: 1. Selection and construction of proper mechanism 2. Literature survey 3. Design and fabrication of components 4. Electromechanical actuator development 5. Electronic integration

Chapter 2 LITERATURE REVIEW

2.1 RECENT RESEARCH & DEVELOPMENT IN CAMLESS ENGINES

History shows that the idea of a camless internal combustion engine has its origins as early as 1899, when designs of variable valve timing surfaced. It was suggested that independent control of valve actuation could result in increased engine power. More recently, however, the focus of increased power has broadened to include energy savings, pollution reduction, and reliability.

To provide the benefits listed above, researchers throughout the previous decade have been proposing, prototyping, and testing new versions of valve actuation for the internal combustion engine. Their designs have taken on a variety of forms, from electro-pneumatic (1) to electro-hydraulic (2), (3). These designs are based on electric solenoids opening and closing either pneumatic or hydraulic valves. The controlled fluid then actuates the engine valves.

A comprehensive project using solenoid control of pneumatic actuators was completed in 1991 (1). This research included the development of the actuators, a 16 bit microprocessor for control, and comparative testing between a standard Ford 1.9 litre, spark ignition, port fuel injected four cylinder engine and the same engine modified for camless actuation. Testing compared the mechanism of unmodified engine to that of the same engine, altered to include eight pneumatic actuators in place of the standard camshaft. As Gould et al states, their work cannot be considered feasible for implementation due to the high power requirements of the actuator. Furthermore, concerns related to the lack of research for the gas flow dynamics in variable valve timing designs were raised by the authors. The altered flow dynamics may have contributed to inconsistently favourable results.

Research has been done by University of South Carolina on this using hydraulic actuator and piezoelectric stack which is the latest progress in this field.

One Electromechanical Valve Train (EMVT), developed by Siemens Automotive Systems has already been demonstrated at full load in a 16-valve four-cylinder engine. Jacobs Vehicle Equipment Co is another company involved in this field of research, but in diesel truck engines. Their direction is towards the Electrohydraulic Valve Actuation Technology (EHVT). International Truck and Engine Corp is another engine manufacturer poised to take a huge step forward in diesel engine design, announcing that it will eliminate camshafts from its diesel engines and replace them with camless electronic-valve timing systems. Camless engine technology is soon to be a reality for commercial vehicles. In the camless valve train, the valve motion is controlled directly by a valve actuator – there is no camshaft or other connecting mechanisms. Precise electro-hydraulic camless valve train controls the valve operations (opening, closing etc). 2.2In recent years camless engine has caught much attention in the automotive industry. Camless valve train offers programmable valve motion control capability. However, it also introduces valve train control issues. There are mainly two types of camless actuators: electro-hydraulic valve (EHV) and electromechanical valve (EMV) actuators. This report deals with the EMV type of actuator. The EMV system discussed in this paper is slightly different from the previous experimental system that the authors had worked on. First of all, stronger springs are used in current system setup in order to get faster closing. Secondly, there is no physical lash spring between the engine valve and armature in the new system. The engine valve stem is directly in contact with the armature of the electromagnet. A lash, the clearance between the valve step and the armature when each is seated to its own mechanical stops (valve seat and electromagnet) respectively, of 0.15-0.25 mm is maintained to allow for the valve stem thermal expansion. Thirdly, the position measurement of armature is used for feedback control. The engine valve position is still being monitored, but only for the purpose of modelling and performance evaluation.
For an EMV system, the control of engine valve seating velocity has been identified to be a critical problem. The motion of an engine valve on a conventional engine is driven by a camshaft and constrained by a spring to follow the cam profile. Therefore, small seating velocity is not difficult to achieve. For a camless valve train, however, a control system is required to maintain the seating velocity below a given level. Variable valve timing was introduced in the late 20th century in order to improve to improve power output and now the aim has almost completely shifted to improvement in fuel economy. Variable valve timing developed in the time being and has come into the market as camless engine which use electro-mechanical actuator system. This type of system uses an armature attached to the valve stem. The outside casing contains a magnetic coil of some sort that can be used to either attract or repel the armature, hence opening or closing the valve. The benefits of camless valve actuator systems are numerous. The most obvious one - infinitely variable valve timing. More torque is made available throughout the rev-range due to the valve timing changes enabling optimal volumetric efficiency (hamazaki et al 1991). This increases engine performance and decreases fuel consumption, also decreasing harmful emissions, increasing durability and engine life. The amount of engine oil required would also be dramatically reduced because no lubrication would be required for the traditional complex camshaft valve system. Cold start wear would also be minimal of the valve train hardware. There is also a general consensus that electromechanical valve actuation will increase overall valve train efficiency by eliminating the frictional losses of the camshaft mechanism, the weight of the mechanism and the cam mechanism's drain of power from the crankshaft. Control of an electromechanical actuator from camless engine
Chun Tai, Tsu-Chin Tsao
Department of Mechanical and Aerospace Engineering
University of California at Los Angeles

The cycle of opening and closing of a valve driven by a mechanical camshaft will display a shape similar to a sine curve ( tsui chao et al 2000). The opening period (as measured in crankshaft degrees) remains constant for any engine load or rpm. However, the cycle of opening and closing of valves driven by the electromechanical valve actuators operates much faster. Designed to match valve-opening rates at the maximum engine rpm, the electromechanical valve actuators open the valve at this same rate regardless of engine operating conditions.

Figure 2.1 valve opening and closing

An EMCV actuator works according to the spring-mass pendulum principle, which means that the system follows its own natural oscillation frequency, and external electromagnetic force is only needed for overcoming the friction loss.

Electromechanical Camless Valve train (EMCV) offers potential for making a high-performance engine. However, the quite-seating issue must be resolved before commercializing this product. This means that a control system is required to maintain the seating speed below a given level. In the EMCV seating control, the nominal electromagnetic force for seating control is less than the spring force when the valve lift is relatively large. However, as the valve lift gets smaller and smaller, the electromagnetic force will get closer and closer to the spring force, and eventually totally balance the spring force and hold the valve at the seating position. Since almost-zero valve velocity at seating position is our control target, the system should be linearized around seating position, zero velocity and with holding current.

Modelling and sensor-less control of electromagnetic valve actuator P Eyabi - ‎2006

Electromechanical actuator became the prime choice in order to achieve. Due to their low cost , high productivity , ruggedness and high force density. EMV configuration examined was using two solenoid with a common plunger and a opposing spring. This gives flexible valve actuation system and gives us the direct control of intake and exhaust dynamics thus improving the overall efficiency of the system. The problem in this arises with the plunger seating velocity and the control of the actuation system. The plunger seating velocity can be lowered by various methods. Hoffman and stefanpolou (2001) used a lqr based model in order to lessen the seating velocity and the sensorless control of EMV. Tai (2002) based on a linear magnetic model in order to lessen the seating velocity and on basis of linear magnetic model develop a sensorless control over EMV. Peter etayabi et al. (2005) used almos a similar model we are developing the model consist of two solenoid valve and a plunger in between them . The solenoid are energised by a battery of 100v due to which a intensity magneticl field is generated. This magnetic field attracts the lunger towards it resulting in the opening and closing of the valve. An observer based sensorless control strategy is used in the model.

Fig.2.2 model used by Peter Et.al. 2005

A control system is always needed in order to maintain the seating speed of the valve actuator in the electromechanical actuator. The unstable nature of the electromechanical valve actuator remains regardless of the actuator design parameter. This has led to the sensitivity in the seating speed thus a closed loop control approach has to be used while designing the system rather than the open loop control. There is feedback in the closed loop control approach which helps in better performance factor [5]. Also the pulse width modulated wave is preferred as the signal as it quiet discreet in nature, hence providing the most appropriate signal for the electromechanical valve actuator.

Chapter 3

CAMLESS ENGINE

3.1 CAMLESS ENGINES AND RECENT DEVOLOPMENT
History shows that the idea of a camless internal combustion engine has its origins as early as 1899, when designs of variable valve timing surfaced. It was suggested that independent control of valve actuation could result in increased engine power. More recently, however, the focus of increased power has broadened to include energy savings, pollution reduction, and reliability. To provide the benefits listed above, researchers throughout the previous decade have been proposing, prototyping, and testing new versions of valve actuation for the internal combustion engine. Their designs have taken on a variety of forms, from electro-pneumatic[1] to electro-hydraulic[2], [3]. These designs are based on electric solenoids opening and closing either pneumatic or hydraulic valves. The controlled fluid then actuates the engine valves A comprehensive project using solenoid control of pneumatic actuators was completed in 1991[1]. This research included the development of the actuators, a 16 bit microprocessor for control, and comparative testing between a standard Ford 1.9 liter, spark ignition, port fuel injected four cylinder engine and the same engine modified for camless actuation. Testing compared the unmodified engine to that of the same engine, altered to include eight pneumatic actuators in place of the standard camshaft. As Gould et al states, their work cannot be considered feasible for implementation due to the high power requirements of the actuator. Furthermore, concerns related to the lack of research for the gas flow dynamics in variable valve timing designs were raised by the authors. The altered flow dynamics may have contributed to inconsistently favourable results.
Research carried by university of South Carolina has been done on this using hydraulic actuator and piezoelectric stack which is the latest progress in this field.
One Electromechanical Valve Train (EMVT), developed by Siemens Automotive Systems has already been demonstrated at full load in a 16-valve four-cylinder engine. Jacobs Vehicle Equipment Co is another company involved in this field of research, but in diesel truck engines. Their direction is towards the Electrohydraulic Valve Actuation Technology (EHVT). International Truck and Engine Corp is another engine manufacturer poised to take a huge step forward in diesel engine design, announcing that it will eliminate camshafts from its diesel engines and replace them with electronic-valve timing systems by the year 2007. Camless engine technology is soon to be a reality for commercial vehicles. In the camless valve train, the valve motion is controlled directly by a valve actuator – there’s no camshaft or connecting mechanisms .Precise electrohydraulic camless valve train controls the valve operations, opening, closing etc. In recent years camless engine has caught much attention in the automotive industry. Camless valve train offers programmable valve motion control capability. However, it also introduces valve train control issues. There are mainly two types of camless actuators, electrohydraulic valve (EHV) and electromechanical valve (EMV) actuators. This report deals with the EMV type of actuator. The EMV system discussed in this paper is slightly different from the previous experimental system that the authors had worked on First of all, stronger springs are used in current system setup in order to get faster closing. Secondly, there is no physical lash spring between the engine valve and armature in the new system. The engine valve stem is directly in contact with the armature of the electromagnet. A lash, the clearance between the valve step and the armature when each is seated to its own mechanical stops (valve seat and electromagnet) respectively, of 0.15-0.25 mm is maintained to allow for the valve stem thermal expansion. Thirdly, the position measurement of armature is used for feedback control. The engine valve position is still being monitored, but only for the purpose of modelling and performance evaluation.

For an EMV system, the control of engine valve seating velocity has been identified to be a critical problem. The motion of an engine valve on a conventional engine is driven by a camshaft and constrained by a spring to follow the cam profile. Therefore, small seating velocity is not difficult to achieve. For a camless valve train, however, a control system is required to maintain the seating velocity below a given level.

3.2 PROBLEMS IN CAMLESS VALVETRAINS

Automotive engines equipped with camless valvetrains of the electro-hydraulic and electro-mechanical type have been studied for over twenty years, but production of vehicles with such engines is still not available. The issues that have had to be addressed in the actuator design include: * Reliable valve performance * Cost * Packaging * Power consumption * Noise and vibration

The adoption of an electromagnetic actuator for valve movement poses challenging control problems . The main goal is the achievement of the so called ”soft-touch”: valve should come to the full open and full close positions against mechanical hard stops with very limited speed, comparable to what is achievable with a mechanical cam, in order to reduce acoustical noise and wear of the valve itself. To realize the soft touch functionality, feedback position control is mandatory because system is unstable in positions near to mechanical stop. Given a position trajectory, the feedback controller have to stabilize the plant and achieve reference position tracking.

Noise has been identified as the main problem with the electromechanical actuator technology, arising from high contact velocities of the actuator's moving parts. For this noise to be reduced, a so-called soft-landing of the valves has to be achieved. In a conventional valve train, the soft-landing is mechanically embedded into the shape of the camshaft lobe.

3.3 CAMLESS MECHANISM

To eliminate the cam various mechanisms have been proposed which are given as follows: 1. Hydraulic: In this hydraulic force is used in order to push the valve stem and this can be varied flexibly according to the need of user the mechanism use piezoelectric stack as an important component. This was proposed by university of South Carolina.

2. Electrical: In this the electrical forces and magnetic forces are used in order to bring the flexibility in the mechanism. This is the most common mechanism in the Camless engine.

The mechanism used by us is not electrical and hydraulic but an amalgamation of mechanical and electronics principles. Hence it can be called an electro-mechanical mechanism. .

In this mechanism the the vital component are sensors and electronic control unit. The sensor will send signal to the electronic control unit which comprises of the microprocessor. The microprocessor is programmed accordingly with a software algorithm. This sends the required signal to the actuator. The current is send to the actuator in form of this signal.

A magnetic field is generated by a magnetic field generator and is directed across the fixed air gap. An armature having a current-carrying armature coil is exposed to the magnetic field in the air gap.

When a current is passed through the armature coil and that current is perpendicular to the magnetic field, a force is exerted on the armature. When a current runs through the armature coil and perpendicular to the magnetic field, an electromagnetic vector force, known as a Lorentz force, is exerted on the armature coil. The force generated on the armature coil drives the armature coil linearly in the air gap in a direction parallel with the valve stem. Depending on the direction of the current supplied to the armature coil, the valve will be driven toward an open or closed position. These latest electromechanical valve actuators develop higher and better-controlled forces than those designs mentioned previously. These forces are constant along the distance of travel of the armature because the size of the air gap does not change.

Solenoid is the generic term for a coil of wire used as an electromagnet. It also refers to any device that converts electrical energy to mechanical energy using a solenoid. The device creates a magnetic field from electric current and uses the magnetic field to create linear motion. Common applications of solenoids are to power a switch, like the starter in an automobile, or a valve, such as in a sprinkler system.

Figure 3.1 Shows the working of solenoid
.

A solenoid is a coil of wire in a corkscrew shape wrapped around a piston, often made of iron. As in all electromagnets, a magnetic field is created when an electric current passes through the wire. Electromagnets have an advantage over permanent magnets in that they can be switched on and off by the application or removal of the electric current, which is what makes them useful as switches and valves and allows them to be entirely automated.
Like all magnets, the magnetic field of an activated solenoid has positive and negative poles that will attract or repel material sensitive to magnets. In a solenoid, the electromagnetic field causes the piston to either move backward or forward, which is how motion is created by a solenoid coil. In a direct-acting valve, electric current activates the solenoid, which in turn pulls a piston or plunger that would otherwise block air or fluid from flowing. In some solenoid valves, the electromagnetic field does not act directly to open the conduit. In pilot-operated valves, a solenoid moves the plunger, which creates a small opening, and pressure through the opening is what operates the valve seal. In both types, solenoid valves require a constant flow of electrical current to remain open because once the current is stopped, the electromagnetic field disperses and the valve returns to its original closed position

Chapter 4 MODELLING

4.1 Stage I (Initial Concept & Design): The initial concept of our electromechanical valve actuator involved the motion of a magnetic armature. An extension of the armature was welded to the valve stem. Magnetic force was induced in the armature on passage due to the magnetic field produced by the electromagnet fitted on top of it, when current was passed. The return mechanism comprised of a simple compression spring system which push the armature back to its original position (valve closed position) as soon as current flow to the electromagnets is terminated. It was planned that rhythmic electrical impulses from a microcontroller programmed to govern current flow with respect to variations in rpm. It was further planned to programme the microcontroller to allow for continuous variable valve timing. This model was transformed due to certain mechanical and electrical constraints and practical niggles faced during the working and construction of the actual model. One of the major problems encountered was the difficulty in achieving valve frequencies beyond 25 Hz as described in one of the research papers we referred to and which formed the base of this design.

Fig 4.1 CAD drawing of 1st model

4.2 Stage II (Change in design & Development of prototype) The mechanical and financial constraints and complications of the initial design led to a change in basic design of the electromechanical actuator. The two electromagnet design was replaced by a simpler single solenoid coil design in stage II of development. In this mechanism, electrical impulses were used to induce a magnetic field in the solenoid coil which in turn induced magnetic force in an a iron core (armature). An extension of the armature was welded to the rocker arm. The other end of the rocker arm was welded to the valve stem. Rhythmic electrical impulses were used to induce motion in the armature which led to valve lift which was directly proportional to the magnitude of the current passed through the solenoid. The valve return motion was achieved using compression springs, which was same as that in initial design of stage I. A prototype was developed to analyse the valve conditions, frequency limitations, energy losses and to assess the success of the model in a real scenario.

Fig 4.2.1. Stage II Prototype 4.3 Stage III (Programming of Microcontroller) MICROCONTROLLER is a small and low-cost computer built for the purpose of dealing with specific tasks, such as displaying information in a microwave LED or receiving information from a television’s remote control. Microcontrollers are mainly used in products that require a degree of control to be exerted by the user.. The AVR is a modified Harvard architecture 8-bit RISC single chip microcontroller which was developed by Atmel in 1996. The AVR was one of the first microcontroller families to use on-chip flash memory for program storage, as opposed to one-time programmable ROM,EPROM, or EEPROM used by other microcontrollers at the time.
Flash, EEPROM, and SRAM are all integrated onto a single chip, removing the need for external memory in most applications. Some devices have a parallel external bus option to allow adding additional data memory or memory-mapped devices. Almost all devices (except the smallest TinyAVR chips) have serial interfaces, which can be used to connect larger serial EEPROMs or flash chips.
Program instructions are stored in non-volatile flash memory. Although the MCUs are 8-bit, each instruction takes one or two 16-bit words.
The size of the program memory is usually indicated in the naming of the device itself (e.g., the ATmega64x line has 64 kB of flash while the ATmega32x line has 32 kB).
There is no provision for off-chip program memory; all code executed by the AVR core must reside in the on-chip flash. However, this limitation does not apply to the AT94 FPSLIC AVR/FPGA chips.

Chapter 5

EXPERIMENTATIONS &
INVESTIGATIONS

5.1 COMPONENTS OF THE MECHANISM The various parts required in the fabrication of the model we used are given as follow: 1. Cylinder head 2. Solenoid 3. 12V Battery 4. Microcontroller 5. Circuit Board

Most of the parts had to be machined, welded to give it the desired shape in accordance with the final design. Such parts included: Cylinder head Connecting link Plunger

5.1.1 CYLINDER HEAD The cylinder head sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket. In most engines, the head also provides space for the passages that feed air and fuel to the cylinder, and that allow the exhaust to escape. The head can also be a place to mount the valves, spark plugs, and el injectors. Material: Cast Iron Cylinder head is purchased and machined using lathe machine. The cylinder head machined along its upper surface to accommodate the required setup.

Figure 5.1.1(a) Cylinder Head

Figure 5.1.1(b) Machined Cylinder Head

5.1.2 SOLENOID Material: Copper wire Rated voltage: 24 Volt DC supply Iron core plunger Solenoid is purchased and mechanically joined with connecting link, which in turn provides required motion to rocker arm. Solenoid is the generic term for a coil of wire used as an electromagnet. It also refers to any device that converts electrical energy to mechanical energy using a solenoid. The device creates a magnetic field from electric current and uses the magnetic field to create linear motion. Common applications of solenoids are to power a switch, like the starter in an automobile, or a valve, such as in a sprinkler system.

Figure 5.1.2 Solenoid

5.1.3 BATTERY Adaptor and Battery are used in series connection to provide the required voltage of solenoid: Specifications of battery: 12 Volt, 7.5AH An electric battery is a device consisting of one or more electrochemical cells that convert stored chemical energy into electrical energy. Each cell contains a positive terminal, or cathode, and a negative terminal, or anode. Electrolytes allow ions to move between the electrodes and terminals, which allows current to flow out of the battery to perform work. Figure 5.1.3 Battery Adaptor is connected in series with the battery, together they are forming a 24V, 10 AH supply.

6.1.4 MICROCONTROLLER (Pankaj) 5.1.5 COMPONENTS OF CIRCUIT BOARD: (Pankaj) 5.1.5(a) DIODE

The simplest semiconductor device is made up of a sandwich of P-type semiconducting material, with contacts provided to connect the p-and n-type layers to an external circuit. This is a junction Diode. If the positive terminal of the battery is connected to the p-type material (cathode) and the negative terminal to the N-type material (Anode), a large current will flow. This is called forward current or forward biased.
The fundamental property of a diode is its tendency to conduct electric current in only one direction. When the cathode is negatively charged relative to the anode at a voltage greater than a certain minimum called forward breakover, then current flows through the diode. If the cathode is positive with respect to the anode, is at the same voltage as the anode, or is negative by an amount less than the forward breakover voltage, then the diode does not conduct current. This is a simplistic view, but is true for diodes operating as rectifiers, switches, and limiters. The forward breakover voltage is approximately six tenths of a volt (0.6 V) for silicon devices, 0.3 V for germanium devices, and 1 V for selenium devices.

5.1.5(b) TRANSFORMER

A transformer is an electrical device that takes electricity of one voltage and changes it into another voltage. You'll see transformers at the top of utility poles and even changing the voltage in a toy train set.
Basically, a transformer changes electricity from high to low voltage using two properties of electricity. In an electric circuit, there is magnetism around it. Second, whenever a magnetic field changes (by moving or by changing strength) a voltage is made. Voltage is the measure of the electric force or "pressure" that "pushes" electrons around a circuit.
If there's another wire close to an electric current that is changing strength, the current of electricity will also flow into that other wire as the magnetism changes.
A transformer takes in electricity at a higher voltage and lets it run through lots of coils wound around an iron core. Because the current is alternating, the magnetism in the core is also alternating. Also around the core is an output wire with fewer coils. The magnetism changing back and forth makes a current in the wire. Having fewer coils means less voltage. So the voltage is "stepped-down."
In a Transformer, an iron core is used. The coupling between the coils is source of making a path for the magnetic flux to link both the coils. A core as in fig.2 is used and the coils are wound on the limbs of the core. Because of high permeability of iron, the flux path for the flux is only in the iron and hence the flux links both windings.

5.1.5(c) CAPACITOR A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store energy electrostatically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator). A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store energy electrostatically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e., insulator). The conductors can be thin films of metal, aluminium foil or disks, etc. The 'non conducting' dielectric acts to increase the capacitor's charge capacity. A dielectric can be glass, ceramic, plastic film, air, paper, mica, etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, a capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.
When there is a potential difference across the conductors (e.g., when a capacitor is attached across a battery), an electric field develops across the dielectric, causing positive charge (+Q) to collect on one plate and negative charge (-Q) to collect on the other plate. If a battery has been attached to a capacitor for a sufficient amount of time, no current can flow through the capacitor. However, if an accelerating or alternating voltage is applied across the leads of the capacitor, a displacement current can flow.

5.1.5(d) INTEGRATED CIRCUIT Integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small plate ("chip") of semiconductor material, normally silicon. This can be made much smaller than a discrete circuit made from independent components.

Figure 5.1.5(d) Integrated Circuit

5.1.5(e) CONNECTING LINK Material: Cast Iron Connecting link is welded to the rocker arm at the bottom and is joined to the plunger of the solenoid at the top, to transmit horizontal oscillatory motion of the plunger to the rocker arm.

Figure 5.1.5(e) Connecting Link

5.2 INITIAL STAGE PROTOTYPE

Figure 5.2 Initial Stage Prototype In the previous model the main motive was to minimise the mechanical link and create a mechanism without being dependent on the camshaft for the valve motions. The design was achieved with use of solenoid relay and a connecting link as shown in the figure. This design although fulfilling the project criteria lacked characteristic. The design was not appropriate as it some lost in thrust was there moreover the motion was limited to a single specification hence restraining us to single variation in the project. This lacuna was overcome in the subsequent model which is shown as below.

5.3 FINAL STAGE PROTOTYPE In the previous model we provided the thrust to solenoid through direct current supply which only gave a constant speed reciprocating motion to the coil. According to the RPM of engine, frequency of valve motion needs to be changed. So, we designed a circuit which will provide a variable frequency for the motion of valve. This variation is controlled by a regulator which is none other than a variable resistance. The amount of current supplied is varied with the help of a regulator. The regulator adjusts the magnitude of the current in the circuit by varying the resistance in the circuit board. As the regulator is rotated in the clockwise direction, the current supplied is increased the circuit. With the increase in current, the frequency with which the rocker arm rotates, increases. Thus, with rising current magnitudes the motion and frequency of the valve correspondingly increases. Figure 5.3 Intermediate Stage Prototype

Chapter 4 CONCLUSIONS

The development of the model has proven the concept that the conventional camshaft mechanism can be replaced by incorporating an electromechanical actuator with a variable timing by manipulating it’s actuation through the use of microcontroller and integrated circuits. An electro mechanical valve actuator was designed for a single cylinder 100cc engine. The actuator incorporates the electromechanical principle in which the solenoid when energised pushes the actuator to open the valve and the return action is performed by the spring. The timing of the actuator’s motion is varied using a circuit which incorporates principle of time delay using resistor, capacitor and IC. The voltage required for running the circuit is 24V which is quite nominal to achieve in an automobile. This type of arrangement leads to the flexibility in the opening and closing of the valve. It offers a wider span and range for the opening and closing of the valve which is a step towards engine optimisation. The system employs the consumption of electrical energy which is quite low. The model made has advantage in many terms like the air efficiency of the model is increased which leads to more air intake in the engine cylinder. This has led to the increased efficiency of the engine plus lesser emission. Development in this field has led to increase in efficiency by 3-4%. Also the air dynamics of the engine can be improved thus proper amalgamation of petrol and air can be made by opening the valve for more time and exhaust for more yielding similar results. The model also comes with lesser link which reduces the amount of frictional losses drastically as there are lesser surface contact, moreover the reaction time for the mechanism has improved by leaps and bound.

References( Pankaj) Journals 1. Pischinger M Salber, W.Staay,,” Benefits of electromechanical valve train in vehicle operation sae technical paper 2001-02-2541. 2. T. Hosaka and M. Hamazaki, “Development of the variable valve timing and lift (VTEC) engine for the Honda NSX,” SAE Tech. Paper 910008, 1991 3. Andrew Stubbs,2000,”Modelling and Controller Design of an Electromagnetic Engine Valve,” Masters Thesis in University of Illinois at Urbana 4.Sugimoto G. Sakai, H, Umemto, A., Sihmizu Y,.Ozawa, H, 2004, “Study on Variable Valve Timing System Using Electromagnetic Mechanism,” SAE Tchnical Paper Series, Paper 2004-01-1869 5. Tsui chao, Chun tsang,” Design and control of electromechanical actuator with high seating velocity.,” SAE technical paper series 2003-01-1345 6. Kim.j,”Design and analysis of a new response, latching electromagnetic linear actuator” PHD dissertation in university of California Berekely,USA.