CONTENTS1 INTRODUCTION2 DTS-I ENGINE3 DTS-SI ENGINE4 THE TECHNOLOGY5 SWIRL INDUCTION6 PORT CONFIGURATION7 IMPLIMENTATION OF DTS-SI

INTRODUCTIONBajaj Auto and Hero Honda have been trading punches for the last few months. Not literally, of course, but more on a figurative sense, contesting whether the demand for bikes in the 100cc segment is declining and whether the 100cc+ segment, including the 125cc category, will be the new choice for entry-level bike buyers.

Hero Honda thinks that the 100cc segment is not headed southward and Bajaj opines that the segment will stagnate and eventually decline since bike buyers will graduate to the bigger-engined category just above the entry-level.

But with a 100cc bike in its portfolio, Bajajs proclamation that it will exit the current entry-level segment was rather bold and must have been backed by a breakthrough that it must have managed and which it is focusing on for its future bikes. That in-house technological research and development effort that was being widely speculated about was finally unveiled late last week.In a conventional single spark plug equipped combustion chamber, the rate of combustion is slow. The spark plug situated at one end of the combustion chamber, ignites the air-fuel mixture and the ensuing flame front spreads like a slowly inflating balloon. There is an inevitable delay for this inflating balloon to reach the furthest part of the combustion chamber. Thus, the combustion is slow and inefficient.

DIGITAL TWIN SPARK IGNITION( DTS-I)Well, to start with, DTS-i, although a new concept, is well utilized and advertised by bajaj in 2-wheelers, and honda in 4-wheelers. Put in simple terms, two spark plugs provided at diff points facilitates better ignition and combustion. Thats DTS-iLETS ROLL ON THE ROAD- this is the main mool mantra of Delhi bikers now specially in India every body is getting attracted towards the increasing market of the two-wheelers not the scooters but the BIKES .the companies like Bajaj, Suzuki, Honda etc are giving the teenager generation what they are demanding in bikes.

Like the new XCD DTS-SI 125cc Bajaj bike which is being recently launched in the market. According to Bajaj this bike will be the major reason for the extinction of the 100cc bikes in the market. After the introduction of pulsar dts-si in India it had been worked out for the new technology. It had given a boost in the market of the DTS-SI technology in India. The tagline DEFINITELY MALE got its hand on the Indian market and now they are trying for something new to catch the breathes of the teenagers who are crazy for bikes

Which they had started with the launch of new XCD DTS-SI in the market. The DTS-SI technology means DIGITAL TWIN SPARK-SWIRL. In the combustion chamber of the DTS-SI bikes of the engine there are two spark plugs which enables the faster combustion and also results in better fuel efficiency as compared to the four stroke engines.

The Digital Twin Spark ignition, equipped combustion chamber takes care of the slow rate of combustion in a simple but novel way. The cylinder head is equipped with two spark plugs, instead of the conventional single spark plug. By generating two sparks at either ends of the combustion chamber, (approximately 90( to the valve axis) the Air-Fuel mixture gets ignited such that, there are 2 flame fronts created and therefore a reduction in flame travel of the order of 40% is achieved. A fast rate of combustion is achieved leading to a fast rate of pressure rise. The obvious outcome of this is more torque, better fuel efficiency and lower emissions.WHAT IS DTS-I ?

Figure 1The DTSi (Digital Twin Spark ignition) technology from Bajaj could potentially revolutionise motorcycling in the country. The company may well want to replicate the technology in its other engines as well. This technology, which is also being patented by Bajaj Auto, boosts the performance of the engine, while simultaneously cutting emissions.

The DTSi technology incorporates twin sparkplugs at either ends of the combustion chamber for faster and better combustion. Single sparkplug meant slower burning of the air-fuel mixture and sub-optimal combustion chamber characteristics. This is the heart of the new technology from Bajaj. But, its benefits are fully realised only after it is combined with a computerised direct ignition (CDI) system and new generation throttle response system.

The digital CDI in the new Pulsar, which features an advanced eight-bit microprocessor handles the spark delivery. The programmed chip's memory contains the optimum ignition timing for any given engine rpm, thereby squeezing out the best performance characteristics from the combustion chamber. Working together with the Throttle Responsive Ignition Control System (TRICS III) supposedly also delivers the optimum ignition timing for varying load conditions.

Bajaj has also developed a new third generation TRICS III to complement the new ignition system. The TRICS system controls the ignition based on throttle use. Depending on the needs of the motorcycle rider, whether for cruising or a burst of acceleration (such as for overtaking), the ignition requirements changes; especially useful in city riding conditions.

Based on the level of throttle opened, a magnetic field opens or closes the reed switch, which, in turn, is connected to the Digital CDI. The CDI then switches to the desired Ignition Advance Timing Maps (pre-programmed timing from the eight-bit processor). This helps the engine achieve an ideal ignition spark advance for every throttle opening and engine rpm level.

THE DIGITAL TWISTWith a host of new technologies, the new versions have raised the bar for "digital biking" in India. Bajaj's introduction for the new Pulsar says that the new features include DTSi, TRICS III and digital CDI. Lots of abbreviations that sure must sound intimidating.

Let us try unravelling one acronym at a time.

Current motorcycle and scooter engines have a single spark plug that ignites the air and fuel mixture inside the combustion chamber. As a result, the rectangular combustion chambers in most motorcycle engines have a certain degree of unburnt air-fuel mix, since the flame front arising from the sparkplug does not reach all the corners of the combustion chamber.

This loss of unburnt air-fuel mix leads to lower power and fuel efficiency. After Bajaj Auto perfected the technology for adding a second spark plug to the engine and the engine management systems to go with it, it decided to first put the new technology to work on the Pulsar.DIGITAL TWIN SPARK- SWIRL INDUCTION (DTS-SI SYSTEM)

Figure 2

The Digital Twin Spark - ignition or DTS- i is the mother technology for the latest Digital Twin Spark Swirl induction or DTS-Si technology.

Thanks to DTS- i, a fast rate of combustion and therefore the resulting fast rate of pressure rise is harnessed, by optimally positioning this pressure, to deliver maximum possible work and hence obtain more torque, better fuel efficiency and lower emissions.

When burning lean Air-Fuel mixtures, the two plugs provide rapid combustion, but at light loads, opportunity exists to improve the combustion further.

Figure 3

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.

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 optimised 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 Pulsar. A combination of DTS-i and Swirl induction thus provides extremely rapid combustion, resulting in high efficiency.

The latest technology that Bajaj is showcasing is a 125cc engine that has the newly developed DTS-Si (Digital Twin Spark-Swirl induction) technology. The new engine with swirl induction is expected to give an amazing mileage of 109 km per litre under ideal (standard) test conditions, which is higher than the mileage the current 100cc motorcycles offer.

The swirl is caused inside the cylinder by the valve angle. It improves the air fuel mixture allowing the engine to run in leaner mixture. Induction is the process of getting air into the engine. Every engine has to have small amount of swirl atleast, otherwise the combustion spark will not spread enough. A lot of fuel will remain unburnt when the piston reaches the BDC. So naturally increasing the swirl will increase the amount of fuel burnt. Honda engines are known to have the highest swirl and that is why they are very efficient. So swirl induction does not really mean any thing new or any change in the engine. They will probably increase the fuel efficiency only by tuning it for efficiency.Iducction swirl is a very old idea- u can find it in text books 30 years old. basically its about promoting a turbulence while inducting the A/F mix into the combustion chamber, so that the mix is homogenous and uniform-ensuring uniform flame propagation. Now all petrol engines make use of some kind of mechanism (contours) for induction swirlBajaj feels that with this breakthrough technology, it has the potential and opportunity to offer an upgrade to the 100cc bike customer, a two-wheeler with an engine which offers the best of both worlds 100cc type mileage and 125cc-class performance.

The technology has been designed and developed completely by **Ahead, Bajaj Autos in-house R&D. Can it revolutionise the industry by turning out to be Indias most fuel-efficient two-wheeler engine.THE TECHNOLOGYBajaj Auto, has achieved another breakthrough with the launch of new Digital Twin Spark - Swirl induction (DTS-Si) engine. The new 125cc engine with DTS-Si technology will give an amazing mileage of 109 kilometers per liter under ideal test conditions surpassing the mileage of all current 100cc motorcycles. With this breakthrough there is a huge potential and opportunity to upgrade the 100cc customer with a engine which offers the best of both worlds 100cc mileage and 125cc performance.Bajaj had first dramatically improved on existing engine technology in 2003 when it launched the DTS-i (Digital Twin Spark-ignition) engine with two Spark plugs located at opposite ends of the combustion chamber (as compared to a single spark plug in conventional 4-stroke engines) to achieve faster and more efficient combustion. The DTS-i technology offered better performance, improved fuel efficiency with lower emissions and helped establish the Bajaj Pulsar and then the Bajaj Discover as leaders in their respective segments.

The DTS-i Engine can be further engineered to deliver either exceptional performance or exceptional mileage. Bajaj Auto worked on the mother DTS-i technology to design the DTS-Si engine to deliver outstanding mileage. The DTS-Si technology gives the highest possible fuel efficiency by introducing Swirl induction to the DTS-i engine to create turbulence in order to achieve extremely efficient combustion.

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.In a conventional single-spark-plug-equipped combustion chamber, and the rate of combustion is relatively slow. 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. The Digital Twin Sparkignition (DTS-i) technology that Bajaj developed a few years ago and has incorporated in many of its current engines, takes care of the slow rate of combustion in a simple but 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.

While that sounds logical and simplistic, TVS Motor claims that the same effect is achieved by employing a single spark plug with differential sparking cycles.

There would be a depression on the piston dome which will make the air-fuel mixture 'swirl' (This swirl is actually turbulence created in the fuel+air charge and has been achieved by altering the shape / size / dimensions of the port, and it is a fact that turbulence leads to better combustion.) when it charges into the cylinder over the piston due to physical restrictions, this design is common in bigger engines (Diesel Engines). Basic books on engines printed (in as early as 1940's) have this design clearly mentioned. The intake 'pipe' may look different to cause good 'swirl' before getting ignited. This designs were used for diesel engines to mix air and fuel efficiently as the fuel was directly injected into the combustion chamber. Bajaj feels the mixing efficiency of air n fuel in carburettor is not enough, it feels by further swirling the engine becomes very fuel efficient to classify it as a "New Platform". This is utter non-sense, it's just figment of imagination. The business model of Bajaj goes like this "New Models-New Hype-Increased sales".SWIRL INDUCTIONThanks to DTS-i, a fast rate of combustion and, therefore, the resulting fast rate of pressure rise, is harnessed by optimally positioning this pressure. Bajaj R&D observed that when burning lean air-fuel mixtures, the two plugs provide rapid combustion, but at light loads, opportunity exists to further improve the combustion quality. Usually under such conditions, the quality and concentration of the air-fuel mixture will vary from one area to another within the combustion chamber. However, combustion efficiency in lean air-fuel mixture conditions can be further improved by generating swirl (This swirl is actually turbulence created in the fuel+air charge and has been achieved by altering the shape / size / dimensions of the port, and it is a fact that turbulence leads to better combustion ) in the combustion chamber.

In swirl induction the air fuel mixture intake is caused to swirl and hence resulting in optimum combustion at low rpm. This may be done with the engine having only one valve opening up at low rpm, thereby resulting in a swirling effect for the air fuel mixture. it may also be done by having a valve with optimised geometry to create a swirl effect in the flow and hence enhance the particulate distribution and thus reduce the wear and tear on the machinery.

It can also be described as an intake control device which will generate a strong swirl within the bike' cylinder during low rpm without any substantial drop in power output.

When high turbulence is generated and combustion takes place, the surface of the ballooning flame front fragments itself, with projection like fingers, and this increases its surface area, thereby improving combustion further.Pulsar 180 DTSiwith XCD 125 DTS-Si

Figure 4Table 1

Pulsar 180 DTSiXCD 125 DTS-Si

ManufacturerBajaj Auto LtdBajaj Auto Ltd

ModelPulsar 180 DTSiXCD 125 DTS-Si

Engine Type-180cc, 4 Stroke,Digital Twin Spark- Ignition 125 cc, 4 Stroke, Digital Twin Spark - Swirl induc

Displacement-180cc125 cc

Max Power16.5bhp(12.28kw)@8000rpm9.53 Ps @ 7000 rpm

Max Torque15.22Nm@6000rpm10.85 Nm @ 5000 rmp

Overall Length-1980 mm

Overall Width-760 mm

Overall Height-1200 mm

Wheelbase1320mm1275 mm

Kerb Weight-113 kg

Ground Clearence-170 mm

Suspension FrontTelescopic Forks 135 mm store with anti-stiction bushesTelescopic (125 mm travel)

Suspension RearTriple rate spring ,5-way adjustable , gas assisted Nitrox shock absorbers with vertical travel of 100mmSwing arm with 5 - step adjustable, shock absorbers with Dual 'SNS' type Spring

Break Front-Mechanically expanding shoes, Drum type,130 mm

Break Rear-Mechanically expanding shoes, Drum type, 130 mm

System Voltage-12 volts 5Ah MF type

Other45-50 kmpl90 Kmph

PORT CONFIGURATIONHowever, the straight ports used in conventional engines have limitations in generating high swirl values due to their geometry. One of the ways of generating more turbulence or swirl is to have a port configuration that promotes this phenomena. To generate the required level of swirl, an offset port configuration was arrived upon and optimised by Bajaj engineers. 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 quick combustion. The values of turbulence achieved now, are substantially higher than that of a straight port cylinder head, such as in the Pulsar. A combination of DTS-i and Swirl induction thus provides extremely rapid combustion, resulting in higher efficiency.

Swirl induction has been used in passenger cars with great success. This is the first time that a similar technology has been adopted in a two-wheeler engine in India. How efficient and successful it is at improving the on-road performance of a two-wheeler is something that we can check out next month when Bajaj launches its first bike on the new technology platform.

IMPLIMENTATION OF DTS-SI

INCLUDEPICTURE "D:\\gaurav\\Bajaj XCD 125 DTS-Si GadgetGyan_com_files\\xcd_2.jpg" \* MERGEFORMATINET

INCLUDEPICTURE "D:\\gaurav\\Bajaj XCD 125 DTS-Si GadgetGyan_com_files\\xcd_3.jpg" \* MERGEFORMATINET Bajaj XCD 125 DTS-Si Figure 5FOR PEOPLE WHO WANT SPEED, ECONOMY , AND PASSION OF RIDING 125C.C BIKE WITH POWER & LOOK OF 150C.C. AND MILAGE OF 100C.C.

XCD is short for eXCeeD, while Si stands for Swirl induction. Bajaj is claiming that this 125 cc bike will exceed the mileage of all other bikes including the 100 cc bikes,The 124.58 cc mill having bore x stroke of 54 x 54.4 mm has swirl induction, which is supposed to be the magic behind this bike. This swirl is actually turbulence created in the fuel+air charge and has been achieved by altering the shape / size / dimensions of the port, and it is a fact that turbulence leads to better combustionAccording to the September 2007 issue of Overdrive Magazine the initial Fuel Efficiency of the XCD has been found to be around 70 plus Km/l in real city conditions. Which according to Over drive, puts the XCD among the most fuel efficient motorcycles in India along with the Fuel Injected Glamour Fi.WHAT IT CAN NOT DO

Can we make a super-frugal scooter with DTS-Si?Given that DTS-Si is a tech-idea that works primarily on the engine head, there's no reason why this would not be possible. However, a 'wasteful' variomatic transmission would more or less put paid to all the efficiency benefits gained from the technology and render the application pretty much without major benefits.

Could there be a DTS-Fi-Si?

Well, no. You see, a powerful, high-revving engine is usually optimised to produce big power and big revs. At high revs, you need each cycle to get over quickly so the next one can begin. Which means the engine head is designed for flow lots of mixture (greater volumetric efficiency), rather than produce a super-clean burn on a lean mixture at low flow speeds (greater combustion efficiency). That's why the next DTS-Fi evolution has more chance of being a four-valve head (two intake valves flow more air-fuel mix than one) than a DTS-Fi-Si.

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SEMINAR REPORT

ON

DIGITAL TWIN SPARK SWIRL INDUCTION (DTS-SI SYSTEM)

SUBMITTED TO: SUBMITTED BY:

Mr Aman Panjeta Gaurav kumar

Lect. Mechanical Engg. Deptt. Roll no : 1204416

JMIT, Radaur Branch : Mechanical

(final yr)

SETH JAI PARKASH MUKAND LAL INSTITUTE OF ENGINEERING AND TECHNOLOGY,

RADUR (YAMUNANAGAR)

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