Digital Triple Spark Ignition

Digital Triple Spark Ignition

1. CHAPTER

INTRODUCTION

It is very interesting to know about complete combustion in automobile

engineering. Because in actual practice, perfect combustion is not at all possible due to

various losses in the combustion chamber as well as design of the internal combustion

engine. Moreover the process of burning of the fuel is also not instantaneous. However

an alternate solution to it is by making the combustion of fuel as fast as possible. This

can be done by using two spark plugs which spark alternatively at a certain time interval

so as increase the diameter of the flame & burn the fuel instantaneously. This system is

called DTSI (Digital Spark Ignition system). In this system, due to sparks, combustion

will be complete.

The spark-ignition engine refers to internal combustion engines, usually petrol

engines. The combustion process of the air-fuel mixture is ignited by a spark from

a spark plug.The working cycle of spark-ignition may be either two-stroke or four

stroke. The working of four-stroke spark-ignition engine is based on Otto cycle. And it

consists of following four strokes;

Suction stroke

Compression stroke

Expansion stroke

Exhaust stroke

Each of its stroke consists of 180 degree rotation of crankshaft rotation and

hence a four-stroke cycle is completed through 720 degree of crank rotation. Thus for

one complete cycle there is only one power stroke while the crankshaft turns by two

revolutions.

SNGIST ,North Paravur, Manjaly Dept of Mechanical Engineering1


Fig 1.1 Otto Cycle.



Fig 1.2 Four Stroke Engine

1.1. LIMITATIONS OF FOUR STROKE ENGINE.

Incomplete combustion.

Burning of fuel is not instantaneous.

Lower fuel efficiency.

Higher emissions.



2. CHAPTER

DIGITAL TWIN SPARK IGNITION

Bajaj was the first Indian manufacturer to pioneer twin spark plug engines way

back in 2003. Twin spark engines apparently have a benefit over single spark engines as

the “air+ fuel” mixture is burnt more efficiently. Branded as DTS-i (Digital Twin

Sparkplug Ignition), it certainly made a big impact. The proof of which is that a few

years later both TVS and Royal Enfield also came out with its own versions of the twin

spark technology. TVS put it in its 125 cc Flame model and currently all Royal Enfield

models come with twin spark plug engines.

Fig 2.1 Digital Two Spark Ignition.



Fig 2.2 DTS-I Engine

Fig 2.3 Bike with DTS-I engine


http://www.vivacity360.com/wp-content/uploads/2012/10/engine1-dtsi.jpg

http://www.vivacity360.com/wp-content/uploads/2012/10/bajaj-pulsar.jpg


This ignition engine has two Spark plugs located at opposite ends of the

combustion chamberand hence fast and efficient combustion is obtained. The benefits of

this efficient combustion process can be felt in terms ofbetter fuel efficiency and lower

emissions. The, ignition system on the Twin spark is a digital system with static

sparkadvance and no moving parts subject to wear. It is mapped by the integrated digital

electronic control box which alsohandles 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. This technology provides a combination

of the light weight and twice the power offeredby two-stroke engines with a significant

power boost, i.e. a considerable “power-to-weight ratio" compared to quite a fewfour-

stroke engines.

Fig 2.4DTS Engine.


http://www.vivacity360.com/wp-content/uploads/2012/10/200ns-triple-spark.jpg


2.1 MAIN CHARACTERISTICS OF DTS

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

Superior balance

2.2 DTS – SI ENGINE

DTS-SI stands for “Digital Twin Spark Swirl Ignition”. DTS-SI on the other

hand is an upgraded version of the present DTSI technology developed by research and

development team of Bajaj and they have patented it too. Under this technology, the

digital twin spark plugs are located at same place like in DTSI technology engines but in

an inclined or diagonal manner. This offset of things further expounds the process of

combustion and makes the ignition of fuel and air faster, resulting in enhanced power

and expanded fuel efficiency.



Fig 2.5 DTS-I Engine

Fig 2.6 DTS – SI Engine.


http://www.vivacity360.com/wp-content/uploads/2012/10/dtssi.jpg


2.3 DTS – FI ENGINE

DTS-FI stands for “Digital Twin Spark Fuel Injection”, a ‘Bajaj Patented

Technology’. In fuel injection the conventional carburetor has been replaced by injector

which injects fuel in to the engine in a spray form based on the instructions of the

Engine Control Unit (ECU) which is a part of the Engine Management System EMS.

The Electronic Control Unit (ECU) is microprocessor based and is the brain of the fuel

injection system. It processes information sent by various sensors and instantly

determines optimum fueling and spark timing for various engine operating conditions.

The ECU contains detailed information of the engine’s characteristics from which it

picks the necessary data for commanding both fueling & spark timing.



Fig 2.7 DTS-FI Engine.

2.4 ADVANTAGES OF FUEL INJECTION

Increased power output for same cc.

Better low end torque.

Lower fuel delivery & optimization of spark timing.

Improved cold start, quick warm-up and excellent response to sudden

acceleration.

Lower emission levels.

Self-detection and communication of fuel system malfunctioning if any.

Fig 2.8 DTS-FI Engine


http://www.vivacity360.com/wp-content/uploads/2012/10/dtsfi-2.jpg


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. 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.

2.5 ADVANTAGES OF DTS

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.

2.6 LIMITATIONS OF DTS

Complicated design compared to single spark system

Quickly heats up the Engine during idling

Costlier than single spark ignition system



3. CHAPTER

DIGITAL TRIPLE SPARK IGNITION

The “Digital Triple Spark Ignition” (DTS-I) is a three spark plugs provide

unprecedented performance and efficiency – Fast and optimal combustion at part load

conditions results in better fuel efficiency and ensures lower emissions. The high

performance triple spark engine controlled by an advanced Electronic Control Unit, is

the technology of the future. Combustion in a triple spark engine is 27% faster than a

twin spark and 50% faster than a single spark engine.



Fig 3.1 Digital triple spark ignition.


http://www.flickr.com/photos/motorbeam/7656779108


Fig 3.2 Digital triple spark ignition engine

To make use of 3 spark plugs, the pulsar engine houses a pent roof combustion

chamber which in turn allows to house 3 spark plugs in the engine chamber. Out of the

three plugs, the primary plug is the center one and is mounted in an angle and enters the

chamber at the top-center. The other two secondary plugs are mounted below, each

opposite each other and one of them being vertically underneath the primary plug.



The secondary plugs fires a bit after the primary one has fired and the timings

are controlled by the ECU depending on various parameters like throttle position, engine

revs,load on engine and many other stuffs.

1.2. FEATURES

Sequential firing of coils (no wasted spark)

Digital chip controlling all functions

Idle stabilization

Accurate advance curve in 50 RPM steps

Dwell control for low drain on the battery

Black box operation down to 7.5 volts

Timing fully advanced at 3800RPM

LED for static timing

Easy installation

Ignition Coil protection feature – coils are always “OFF” when the engine is

stopped.



1.3. HIGHEST SPARK ENERGY AND DURATION

Fig 3.3 Tri spark ignition system

If the Battery voltage is reduced even slightly the results will shift dramatically

in favor of the Tri-Spark system. The above charts show the spark current at the

electrode. The spike height indicates the spark current. The width indicates spark

duration. In each case the systems were tested with the same 12 volt supply (25 amp),

test equipment and settings. Lucas ignition coils were used for the Competitor A and B

test.



This Technology, for the first time in INDIA was implemented by BAJAJ on

their product Pulsar 200NS. According to Bajaj, these plugs gain an advantage in low-

rev riding condition where it extracts the best economy compared to KTM Duke 200 in

similar conditions it gives as much as 10-13kmpl more, however the difference vanishes

at higher revs and high speed.

Fig 3.4 Bajaj pulsar 200NS



1.4. ADVANTAGES

Easier starting

Superior running with min vibrations and noise

Less emissions

More output power and thermal efficiency

Less prone to plug fouling

Smooth working even at higher rpms

No issues on Cold air intake

No chances of knocking

1.5. LIMITATIONS

Costlier Technology.

Complications in its design.

Fault in ECU can lead to malfunctioning of engine.

Requires high cooling (liquid cooled).

Failure in cooling can cause severe damage to engine.

Heavier engine compared to twin spark and single spark engines.



4. CHAPTER

CONCLUSION

Hence it can be concluded that the application of these technologies in the

present day automobiles will give the 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.



5. CHAPTER

REFERENCES

Heywood JB. Combustion chamber design for optimum spark-ignition engine

performance. Int J Veh Des 1984;

Meyer RC, Meyers DP, King SR, Liss WE. Effects of spark plug number and

location in natural gas engines. J Eng Gas Turb Power1992;

Ramtilak A, Joseph A, Sivakumar G, Bhat SS. Digital twin spark ignition for

fuel economy and emissions on four stroke engines. SAE paper no. 2005-26-

008;2005.


