Post on 11-Sep-2014
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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.
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Digital Triple Spark Ignition
Fig 1.1 Otto Cycle.
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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.
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Digital Triple Spark Ignition
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.
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Digital Triple Spark Ignition
Fig 2.2 DTS-I Engine
Fig 2.3 Bike with DTS-I engine
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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.
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Digital Triple Spark Ignition
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.
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Digital Triple Spark Ignition
Fig 2.5 DTS-I Engine
Fig 2.6 DTS – SI Engine.
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Digital Triple Spark Ignition
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.
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Digital Triple Spark Ignition
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
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Digital Triple Spark Ignition
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
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Digital Triple Spark Ignition
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.
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Digital Triple Spark Ignition
Fig 3.1 Digital triple spark ignition.
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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.
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Digital Triple Spark Ignition
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.
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Digital Triple Spark Ignition
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.
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Digital Triple Spark Ignition
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
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Digital Triple Spark Ignition
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.
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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.
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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.
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Digital Triple Spark Ignition
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