TABLE OF CONTENTSNO. TITLEPAGE NO. ABSTRACT iii LIST OF FIGURES.....................................................................................iv

1.INTRODUCTION1.1 GENERAL...............21.2 MAIN CHARACTERISTICS..................................5

2.CONSTRUCTION2.1 ENGINE CONSTRUCTION....................................................................72.2 CONSTRUCTIONAL DETAILS.............................................................72.3 VALVE DESIGN......................................................................................82.4 FUEL FEED.............................................................................................113.WORKING3.1 PROBLEM WITH HIGH CAPACITY BIKES.......................................133.2 COMBUSTION BEFORE DTS-I TECHNOLOGY................................143.3 HOW DTS-I SOLVES THE PROBLEM................................................14 3.3.1 TRICS III..................................................................................16 3.3.2 C.D.I..........................................................................................17 3.3.3 BASIC PRINCIPLES................................................................18 3.3.4 IGNITION.................................................................................203.4 MATHEMATICAL MODEL.................................................................23

4. ADVANCEMENTS4.1 TECHNICAL IMPROVISATIONS......................................................26 4.1.1 DTS-SI TECHNOLOGY...............................................................27 4.1.2 DTS-FI TECHNOLOGY...............................................................294.2 STATISTICS...........................................................................................324.3 ADVANTAGES &DISADVANTAGES................................................33

5. CONCLUSIONREFERENCES

30

CHAPTER:1

INTRODUCTION

1.1 GENERALA conventional 4 Stroke engine has a Single Spark Plug located at one end of the combustion chamber and hence the combustion is inefficient leading to sub optimal mileage and sub optimal performance & can even have problems with oil flow. Hence forth there was a requirementto change engines' design, fuelling, ignition, production and quality toachieve the following objectives. Uniform power delivery in alloperating conditions:- A high degree of drivability First rate standards of reliability Long service life.With a view to overcome the above limitations a new patent wasintroduced that is known as DTS-I technology & its use is increasingday by days. DIGITAL TWIN SPARK ignition engine has two Sparkplugs located at opposite ends of the combustion chamber andhence fast and efficient combustion is obtained. The benefits of this efficient combustion process can be felt in terms of better fuel efficiency and lower emissions. The ignition system on the Twin spark is a digital system with static spark advance and no moving parts subject to wear. It is mapped by the integrated digital electronic control box which also handles fuel injection and valve timing. It features two plugs per cylinder

DIFFERENCE BETWEEN CONVENTIONAL 4-STROKE AND DTS-i ENGINE

This innovative solution, also entailing a special configuration of thehemispherical combustion chambers and piston heads, ensures a fast,wide flame front when the air-fuel mixture is ignited, and therefore lessignition advance, enabling, moreover, relatively lean mixtures to beused. This technology provides a combination of the light weight andtwice the power offered by two-stroke engines with a significant powerboost, i.e. a considerable "power-to-weight ratio" compared to quite afew four-stroke engines. The actual picture of Bajaj Pulsar Bike is

Moreover, such a system can adjust idling speed & even cuts off fuel feed when the accelerator pedal is released, and meters the enrichment of the air-fuel mixture for cold starting and accelerating purposes; if necessary, it also prevents the upper rev limit from being exceeded. At low revs, the over boost is mostly used when overtaking, and this is why it cuts out automatically. At higher speeds the over boost will enhance full power delivery and will stay on as long as the driver exercises maximum pressure on the accelerator.

1.2 MAIN CHARACTERISTICS

Digital electronic ignition with two plugs per cylinder and two ignition distributors; Twin overhead cams with camshaft timing variation; Injection fuel feed with integrated electronic twin spark ignition; A high specific power; Compact design and Superior balance;This power unit, equipping the naturally aspirated 2-litre used on the Alfa 164, is a direct dilative of the engine fitted on the 2.0 Twin Spark version of the Alfa 75, a recent addition to the Alfa car range. It includes a number of exclusive engineering solutions resulting in superior power output and exceptional peak torque for this cylinder capacity. Its main characteristics are:

Digital electronic ignition with two plugs per cylinder and two ignition distributors Twin overhead cams with camshaft timing variation Injection fuel feed with integrated electronic twin spark ignitionCylinder capacity amounts to 1,962 cc thanks to an 84 mm bore and 88.5 mm stroke with the Compression ratio 10: 1.Maximum power output at 5,800 rpm is a remarkable 148 BHP DIN, while maximum torque, of 19 mkg DIN, is reached at 4,000 rpm. The shape of the torque curve has been perfected to make available fully 16 mkg when revving speed reaches 2,000 rpm and 18 mkg as early as 3,000 rpm, thus making the engine's performance much more responsive.

CHAPTER:2

CONSTRUCTION

2.1ENGINE CONSTRUCTIONThe engine used on the Alfa 164 T. Spark is a four-in-line cylinder unit whose weight has been considerably reduced with all aluminium-alloy engine block, cylinder head, oil sump and tappet covers. Eight counterweights ensure optimal balancing of the high strength nitride steel crankshaft. The pressed-in cast iron cylinder liners feature wet mounting for more effective heat dissipation.

2.2 CONSTRUTIONAL DETAILS

The construction of DTS-i engine is same as that of the conventional 4-Stroke engine. It consists of following parts: Piston Cylinder Crankshaft Connecting rod Fly wheel Carburettor 2-sparkplug 2-ports 2-valvesHere the only change made is that the 2 sparkplug placed at the two opposite end of the combustion chamber At 90 degree to each other.

2.3 VALVE DRIVEThe twin overhead cams, driven by a double chain, act directly on theValves set in a tight Vee configuration (46o). The timing of the valve

TIGHT VEE CONFIGURATION OF VALVES

train is not fixed as in most present day engines, but can be adjusted by a patented device conceived and produced by Alfa Romeo,the timing variation. This is an electro-hydraulic actuator keyed onto the gear that drives the camshaft acting on the intake valves. This actuator enables the camshaft to be shifted into two different angular positions and to modify the intake valve opening durations. Its operation is controlled by the electronic control box of the integrated ignition and fuel injection system.Valve timing actuator logic is predetermined so that overlap - i.e. that fraction of the engines operating cycle when both the exhaust and the intake valves are open simultaneously is shorter at low revs and with lighter loads and longer at higher engine speeds when extra power is required

At high and medium-high engine speeds or whenever additional power has to be provided (normal timing) cylinder filling is optimal, maximizing power output and torque At low and medium-low revs and lighter loads (delayed timing), fluctuation-free operation is ensured combined with a reduction in specific consumption At all engine speeds, noxious emissions are minimized.

PICTURE SHOWING INTAKE AND EXHAUST VALVES

2.4 FUEL FEEDThe Alfa 164 T. Spark power plant is equipped with the ML 4.1 Bosch Motronic multi-point injection system, controlled by the same microprocessor which governs the twin spark ignition and variable valve timing Systems.The excellent volumetric efficiency of the Twin Spark engine is also enhanced by the special straight section individual intake man folding that cuts down losses and fully exploits intake resonance for better mid-range torque.Having all thermodynamic cycle components under the wings of a single electronic control unit means that the power plant used on the Alfa 1 64 T. Spark can guarantee-in addition to outstanding torque and power figures-regular, smooth running at all speeds regardless of load. Moreover, this engine features particularly attractive specific fuel economy compared with rival naturally aspirated units in the same displacement class (with savings of up to 20- 25%).

CHAPTER:3

WORKING

3.1THE ACTUAL PROBLEM WITH HIGHER CAPACITY BIKES:The central problem in the higher capacity bikes is its higher capacity(i.e. larger bore) it self. As the capacity is higher its intake of fresh charge (air fuel mixture) will usually gets increases which in turn increases the fuel consumption. And also the complete combustion of the fresh charge that entered the combustion chamber is not assured, because initially the capacity is higher, therefore the flame front of the spark ignited by the spark plug has to travel the additional distance of increased bore in order to fire the charge at the farthest corners of the cylinder thereby slackening the combustion process. There must be some modifications in the engine design to eliminate these problems in higher capacity bikes. The application of Digital twin spark ignition technology can eliminate this problem up to maximum extent

3.2 COMBUSTION PROCESS BEFORE USING DTS-I TECHNOLOGY

The orthodox single cylinder, four-stroke, spark ignition engine isgenerally equipped with a single spark plug. The fresh charge (air fuel mixture) that entered the cylinder during the suction stroke is compressed during the compression stroke resulting the increase of pressure and temperature of the charge. The spark plug, usually situated at one end of the combustion chamber, ignites the air-fuel mixture and the ensuing flame spreads like a slowly inflating balloon. There is an inevitable delay for this inflating balloon to reach the furthest part of the combustion chamber. So there are pockets of poor combustion within the chamber and, overall, the combustion is slow and inefficient.When it comes to higher capacity engines the distance to be travelled by the flame front is further increased resulting the still slower combustion.

3.3 HOW DTS-i ENGINE SOLVES THE PROBLEM?

The Digital Twin Spark Ignition technology takes care of this slower combustion problem in a simple but a novel way. The cylinder head is equipped with two spark plugs, instead of the usual one. By generating two sparks at either ends of the combustion chamber, (approximately 90 to the valve axis) the air-fuel mixture gets ignited in a way that creates two flame fronts and, therefore, a reduction in flame travel of the order of 40 per cent is achieved. A fast rate of combustion is achieved leading to faster rise in pressure. The obvious outcome of this is more torque, better fuel efficiency and lower emissions. An electronic device (microprocessor) controls the firing order of these twin spark plugs.The fresh charge that entered the cylinder during the suction stroke is compressed during the compression stroke. Then a spark will be ignited by one of the twin spark plugs and the flame front begins to expand like an inflating balloon. In the mean while another spark will be ignited by another spark plug as per controls of the microprocessor. The flame front also begins to expand like an inflating balloon. Therefore the areas that are not covered by the first flame front will be covered by second flame front resulting in the complete & rapid combustion of the fuel.However, this technology even though proved as a successful one all bike-manufacturing companies are not incorporating this technology in their models. Their idea is this faster rate of combustion can be achieved by employing a single spark plug with differential sparking cycles.There are some advance technology used in DTS-i engine which makes it more powerful than the conventional single sparkplug 4-stroke engine like1. Tricks III technology2. CDI technology

3.3.1 TRICS IIIThrottle Responsive Ignition Control System 3rd generation. It is a means of controlling the Ignition by operating the Throttle. Depending on the needs of the Rider whether it be cruising, acceleration or max speed, the ignition requirements constantly change. Based on a particular amount of Throttle opening, the Magnetic field generated by the Magnet opens or closes the Reed switch. The Reed switch is connected to the Digital CDI, which signals the CDI to change/switch, the desired Ignition Advance Timing Maps. This helps in achieving a good balance between driveability and Optimum Ignition Spark advance, resulting in an almost perfect Ignition Spark advance for every Throttle opening and Engine rpm.

3.3.2 C.D.ICapacitor discharge ignition (CDI) or thyristor ignition is a type of automotive electronic ignition system which is widely used in outboard motors, motorcycles, lawn mowers, chainsaws, small engines, turbine-powered aircraft, and some cars. It was originally developed to overcome the long charging times associated with high inductance coils used in inductive discharge ignition (IDI) systems, making the ignition system more suitable for high engine speeds (for small engines, racing engines and rotary engines). The capacitive-discharge ignition uses capacitor discharge current output to fire the spark plugs.

Capacitor discharge ignition3.3.3 BASIC PRINCIPLESMost ignition systems used in cars are inductive discharge ignition (IDI) systems, which are solely relying on the electric inductance at the coil to produce high-voltage electricity to the spark plugs as the magnetic field collapses when the current to the primary coil winding is disconnected (disruptive discharge). In a CDI system, a charging circuit charges a high voltage capacitor, and at the instant of ignition the system stops charging the capacitor, allowing the capacitor to discharge its output to the ignition coil before reaching the spark plug.A typical CDI module consists of a small transformer, a charging circuit, a triggering circuit and a main capacitor. First, the system voltage is raised up to 250 to 600 volts by a power supply inside the CDI module. Then, the electric current flows to the charging circuit and charges the capacitor. The rectifier inside the charging circuit prevents capacitor discharge before the moment of ignition. When the triggering circuit receives triggering signals, the triggering circuit stops the operation of the charging circuit, allowing the capacitor to discharge its output rapidly to the low inductance ignition coil. In a CD ignition, the ignition coil acts as a pulse transformer rather than an energy storage medium as it does in an inductive system. The voltage output to the spark plugs is purely dependent on the design of the CD ignition. Voltages exceeding the insulation capabilities of existing ignition components can lead to early failure of those components. Most CD ignitions are made to give very high output voltages, but this is not always beneficial. When there's no triggering signal, the charging circuit is re-connected to charge the capacitor.The amount of energy the CDI system can store for the generation of a spark is dependent on the voltage and capacitance of the capacitors used, but usually it's around 50 mJ, or more. The standard points/coil/distributor ignition, more properly called the inductive discharge ignition system or Kettering ignition system, produces 25mJ at low speed and drops off quickly as speed increases.Most CDI modules are generally of two types:AC-CDI - The AC-CDI module obtains its electricity source solely from the alternating current produced by the alternator. The AC-CDI system is the most basic CDI system which is widely used in small engines.Note that not all small engine ignition systems are CDI. Some older engines, and engines like older Briggs and Stratton use magneto ignition. The entire ignition system, coil and points, are under the magnetized flywheel.Another sort of ignition system commonly used on small off-road motorcycles in the 1960s and 1970s was called Energy Transfer. A coil under the flywheel generated a strong DC current pulse as the flywheel magnet moved over it. This DC current flowed through a wire to an ignition coil mounted outside of the engine. The points sometimes were under the flywheel for two-stroke engines, and commonly on the camshaft for four-stroke engines. This system worked like all Kettering (points/coil) ignition systems... the opening points trigger the collapse of the magnetic field in the ignition coil, producing a high voltage pulse which flows through the spark plug wire to the spark plug.If the engine was rotated while examining the wave-form output of the coil with an oscilloscope, it would appear to be AC. Since the charge-time of the coil corresponds to much less than a full revolution of the crank, the coil really 'sees' only DC current for charging the external ignition coil.Some electronic ignition systems exist that are not CDI. These systems use a transistor to switch the charging current to the coil off and on at the appropriate times. This eliminated the problem of burned and worn points, and provided a hotter spark because of the faster voltage rise and collapse time in the ignition coil.DC-CDI - The DC-CDI module is powered by the battery, and therefore an additional DC/AC inverter circuit is included in the CDI module to raise the 12 V DC to 400-600 V DC, making the CDI module slightly larger. However, vehicles that use DC-CDI systems have more precise ignition timing and the engine can be started more easily when cold.

3.3.4 IGNITION WITH C.D.I

A Digital CDI with an 8 bit microprocessor chip handles the spark delivery. The programmed chips memory contains an optimum Ignition timing for any given engine rpm, thereby obtaining the best performance characteristics from the combustion chamber. Working together with the TRICSIII system, it delivers Optimum Ignition Timing for varying load conditions. The ignition system on the Twin spark is a digital system with static spark advance and no moving parts subject to wear. It is mapped by the integrated digital electronic control box which also handles fuel injection and valve timing. It features two plugs per cylinder.

This innovative solution, also entailing a special configuration of the hemispherical combustion chambers and piston heads, ensures a fast, wide flame front when the air-fuel mixture is ignited, and therefore less ignition advance, enabling, moreover, relatively lean mixtures to be used. As a result, the adoption of twin spark ignition yields:

A remarkable improvement in thermodynamic efficiency andhence a considerable increase in the amount of poweravailable; more effective combustion at low load and at idling speed; A sizeable reduction in specific fuel consumption; A reduced exhaust emission; Less chance of ignition system failure...(Failure of either circuit will not stop the engine, which can still workwith single spark ignition).

STARTING OF PULSAR DTS-i ENGINE

3.4 MATHEMATICAL MODEL

Governing equations of the cycle model: The energy equation in crank angle basis is written as:==/+/=// To determine instantaneous cylinder volume, pressure, and burned and unburned gas temperatures, the following governing equations have been used()={+/[+[(-r2crsin2).]]} Equations to determine the burnt mass fraction

CHAPTER:4

ADVANCEMENTS IN DTS-i TECHNOLOGY

4.1 TWO NEW TECHNICAL IMPROVISATIONSDTS-i.e. Engine can be further tuned to deliver exhilarating performance or exceptional mileage. The further advances of DTS-I technology are: Digital Twin Spark Swirl Induction (DTS - Si) Digital Twin Spark Fuel Injection (DTS - Fi)

4.1.1 DIGITAL TWIN SPARK SWIRL INDUCTIONNeed for Swirl Induction:The DTS-I technology is the parent technology for this latest DTS-Si technology. Even though a faster rate of combustion is achieved by incorporating the DTS-I technology, there is a chance for further of improvement of rapid combustion process at lighter loads. When there is a sufficient or heavy load on the engine, the 4 stroke cycle completes at a faster rate resulting in the faster combustion because of the twin sparks produced by the twin plugs. But when there exists a lighter load on the engine, the 4 stroke cycle will not complete at a faster rate. Therefore even the incorporation of twin spark plugs cannot aid the faster combustion i.e. still a better rate of combustion can be achieved at lighter loads.Combustion efficiency in lean Air-Fuel mixture conditions can be further improved by generating high turbulence in the combustion chamber. Combustion chambers having low turbulence give rise to propagation of a flame front, which is akin to that of a gradually expanding balloon. This results in a slower rate of combustion and thus slower rate of pressure rise.End result is lower efficiency. When high turbulence is generated and combustion takes place, the surface of the ballooning flame front fragments itself, with projection like fingers, which increases its surface area, thereby improving combustion further.

Here comes the Swirl Induction concept, which is meant for producing higher turbulence in the combustion chamber. Swirl Induction is nothing but imparting a swirling motion to the fresh charge that enters the combustion chamber. This can be done by making slight modifications in the ports positioning of engine.

The picture on this page shows how swirl induction works:-

Actual DTS-i ENGINE

The DTS-Si engine will have two spark plugs but it differs from the parent DTS-I engine in the design of position of the ports. The straight ports used in conventional engines have limitations in generating high swirl values due to their geometry. One of the ways to generate more swirl is to have a port configuration that promotes this phenomena. An offset port configuration was arrived upon and optimized to generate the required swirl numbers. Incorporated in the new engine, this results in a swirling motion of the incoming charge, which decays itself into turbulence as the piston moves in the Induction and Compression strokes.This results in the Air-Fuel mixture being more thoroughly mixed and spread around the combustion chamber. Sparks provided by the twin spark plugs ignite this highly turbulent and compressed Air-Fuel mixture, leading to a flame front with high surface area, resulting in a rapid rise of pressure due to rapid combustion. The values of turbulence achieved now, are substantially higher than that of a straight port cylinder head, such as in DTS-i. A combination of DTS-i and Swirl induction thus provides extremely rapid combustion, resulting in high efficiency.

This technology is applied by Bajaj Auto Ltd in its latest model XCD-125 that delivers an outstanding mileage of 109 kmpl under ideal conditions, which is the best of Indian motorbikes. The DTS-Si engine is far superior to the conventional 4-stroke engines, which dominate the 100cc segment at present. With the new DTS-Si engine the consumer now would not have to compromise between power and mileage - he gets the best of both.

4.1.2DIGITAL TWIN SPARK FUEL INJECTION (DTS - Fi):DTS Fi is another advancement of the parent DTS i technology. Thistechnology is the combination of both DTS i and fuel injection. Thistechnology is meant for increasing the fuel efficiency in power bikes.Generally in conventional 4-stroke engines, which uses petrol as fuel, makes use of carburettor , which mixes the fuel and fresh air in required ratio and supplies the same to the combustion chamber. The process is similar for all loads. But the fuel consumption will be more when there is a heavy load on the engine and it is less when there is a light load on the engine. It is impossible for a conventional carburettor to take care of the fuel supply for these varying loads. Therefore there is a need for some intelligent device that controls the fuel supply according to the varying loads.That so wanted intelligent device is nothing but the Electronic Control Unit (ECU). The Electronic Control Unit is a microprocessor based system and can be regarded as the brain of the fuel injection system.

Fig. showing sectional view of DTS-Fi engine

4.1.3 WORKING OF ECU

Control of Air/Fuel ratioFor an engine with fuel injection, an engine control unit (ECU) will determine the quantity of fuel to inject based on a number of parameters. If the throttle position sensor is showing the throttle pedal is pressed further down, the mass flow sensor will measure the amount of additional air being sucked into the engine and the ECU will inject fixed quantity of fuel into the engine ( most of the engine fuel inlet quantity is fixed). If the engine coolant temperature sensor is showing the engine has not warmed up yet, more fuel will be injected (causing the engine to run slightly 'rich' until the engine warms up). Mixture control on computer controlled carburettors works similarly but with a mixture control solenoid or stepper motor incorporated in the float bowl of the carburettor.Control of ignition timingA spark ignition engine requires a spark to initiate combustion in the combustion chamber. An ECU can adjust the exact timing of the spark (called ignition timing) to provide better power and economy. If the ECU detects knock, a condition which is potentially destructive to engines, and determines it to be the result of the ignition timing occurring too early in the compression stroke, it will delay (retard) the timing of the spark to prevent this. Since knock tends to occur more easily at lower rpm, the ECU may send a signal for the automatic transmission to downshift as a first attempt to alleviate knock.

A full authority throttle control system may be used to control idle speed, provide cruise control functions and top speed limitation.

Control of variable valve timingSome engines have Variable Valve Timing. In such an engine, the ECU controls the time in the engine cycle at which the valves open. The valves are usually opened sooner at higher speed than at lower speed. This can optimize the flow of air into the cylinder, increasing power and economy.

4.2 STATISTICS

The following are the various statistics showing the advantages ofapplication of DTS i & its derived technologies:

4.3 ADVANTAGES AND DISADVANTAGES

4.3.1 ADVANTAGES

Less vibrations and noise Long life of the engine parts such as piston rings and valve stem. Decrease in the specific fuel consumption No over heating Increase the Thermal Efficiency of the Engine & even bear high loads on it. Better starting of engine even in winter season & cold climatic conditions or at very low temperatures because of increased Compression ratio. Because of twin Sparks the diameter of the flame increases rapidly that would result in instantaneous burning of fuels. Thus force exerted on the piston would increase leading to better work output.

4.3.2 DISADVANTAGES

There is high NOx emission If one spark plug get damaged then we have to replace both The cost is relatively more You spend double the amount on spark plugs when it is time to replace them. The engine tends to overheat and loose power at higher speeds as compared to a single plug engine. In case the Engine is kept unused for a long time soiling of spark plugs occur. Twin Spark system helps to reduce this problem.

CHAPTER:5

CONCLUSION

Hence it can be concluded that the application of these technologies the present day automobiles will give the present generation what they want i.e. power bikes with fuel efficiency. Since these technologies also minimize the fuel consumption and harmful emission levels, they can also be considered as one of the solutions for increasing fuel costs and increasing effect of global warming. From this paper I have concluded that perfect Combustion in Internal Combustion engine is not possible. So for the instantaneous burning of fuels in I.C. engine twin spark system can be used which producing twin sparks at regular interval can help to complete the combustion.

REFERENCES

1. Alabastri E., L. Magni, S. Ozioso, R. Scattolini, C. Siviero, and A. Zambelli. Modeling, analysis and simulation of a digital twin spark injection system. In Proceedings of the IFirst IFAC Symposium on Advances in Automotive Control, 2004.2. Baker P. and Watson H. Mpi air/fuel mixing gaseous and liquid plg. SAE Technical Papers, 01(246), 2005.3. Bajaj Auto.com4. Kouremenos D. A. and Hountalas D. T. Development and validation of a detailed fuel injection system simulation model for dtsi engines. SAE Technical Papers, 01(0527), 1999.5. Official Journal L 044, 16/02/2000. Directive 1999/96/EC of the European Parliament and of the Council.6. Wikipedia.org