In the recent years Mazda developed a new technology In this technology we can obtain high fuel efficiency and low emission , this technology is called SKYACTIVE It consisted of Gasoline and diesel four cylinder engines ,these Engines squeeze more energy from the fuel by increasing the compression stroke as for GDI engines , which will lead to better fuel efficiency .

1. Made BY

2. Introduction
 In the recent years Mazda developed a new technology
 In this technology we can obtain high fuel efficiency
and low emission , this technology is called
SKYACTIVE
 It consisted of Gasoline and diesel four cylinder
engines ,these Engines squeeze more energy from the
fuel by increasing the compression stroke as for GDI
engines , which will lead to better fuel efficiency .

4. Gasoline engines:
 In SKYACTIVE-G engines the compression ratio
raised to 14:1 for premium fuel
 It obtain more power from the fuel because of the
larger expansion that occur when the fuel combust,
leading to higher fuel efficiency
 The 2012 Mazda3 with the SKYACTIV-G 2.0L carried
U.S. EPA fuel economy ratings of 40 mpg (5.88 L/100
km) highway, and 28 mpg city (8.4 L/100 km).

5.  A long 4-2-1 exhaust system for reducing the residual
gases.
 The extended pipes are to keep the hot exhaust pulses
form getting pulled by the intake stroke of the other
cylinders, therefore the temperature drops down at
combustion chamber.
 The main advantage of this exhaust is the amount of
residual gas is reduced from 8% to 4%, the
temperature at compression TDC is calculated to
remain the same even when the compression ratio is
increased from 11:1 to 14:1.

6. 4-2-1 Exhaust System

7. Effect of residual gas reduction

8. Residual gas reduction by 4-2-1
exhaust system

9.  The only problem from using the 4-2-1 exhaust system
is the exhaust gases cools down before reaching the
catalytic converter
 This also solved by creating a cavity at the top of the
dome shaped piston this will stabilize the combustion
during retarded ignition.

10. Dome Shaped Piston

11. •The dome shaped piston play a role in increasing
the combustion ratio by reducing of the combustion
chamber
•It will make the combustion faster those knock
which occur at slow flame propagation
•Other advantages of the Cavite is to prevent flame
kernel from beginning in contact with the piston
head therefore reducing the cooling lose

12. Diesel engines
 The SKYACTIV-D engine has the lowest diesel engine
compression ratio of 14.0:1
 It increases the fuel efficiency by 20% and reduces diesel
engine emissions, this is happened by optimizing the
ignition timing.
 In the conventional diesel engines the high compression
ratio leads to high temperature and pressure at the
combustion chamber during compression
 The fuel is injected directly to the high compressed air
 The volumetric combustion (ignition) occurs before
getting a good air-fuel mixture

13.  To avoid all that SKYACTIV-D uses a low compression
ratio, this will decrease the temperature and pressure
in the combustion chamber
 the fuel efficiency is improved because of optimizing
the combustion timing which will lead to higher
expansion ratio.

14. Fig.5: Compression ratio and
diesel combustion
Fig.6: Higher expansion ratio due to lower
compression ratio

15.  The high pressure of ultra high pressure piezo fuel
injectors, create a rich air-fuel mixture
 It is easy to ignite,
 The injector is a high-spec type capable of a maximum
of 9 injections per combustion And to avoid engine
misfiring
 At cold starts the hot exhaust gas back into the
cylinder to warm up the cold air entering the cylinder
during intake stroke

16. Two-stage turbocharger

17. •The engine torque at low speeds is increased by
using two stage turbocharger
•It is consisted of one small and one large turbo
are selectively operated according to driving
conditions
•it also provide sufficient amount of air that helps
to reduce the NOx and Pm emissions.

18. Variable valve lift

19. Friction reduction due to lower compression ratio

20. the mechanical friction was greatly reduced to
the same level as an average gasoline engine

21. SKYACTIV technology developed by Mazda has achieved many great goals by
delivering high fuel efficiency engines with the high torque performance and all
of that happened with the implementation of many methods the most
important one is compression ratio, which is increased up to 14:1 in GDI engines
and reduced to the lowest diesel engine compression ratio of 14.0:1, and this is
done without compromising global emission regulation for clean emissions. in
GDI engines the compression ratio increased by using a dome shaped piston to
reduce the volume of the combustion chamber, also the cavity on the top of the
domed shaped piston shorten the combustion time by giving the flame kernel
more room to burn thus increase the flame propagation and also the other
advantage for the cavity in top of the piston it keeps the flame kernel from been
in contact with the piston head thus reducing cooling loss, this technology
makes light weighted engines ,by using aluminum, more fuel efficient and great
driving performance , this technology will pave the way for many engineers to
develop the internal combustion engines much further in the coming years
Conclusion:

22. [1] Paul Weissler , ”2012 Mazda3 Skyactiv achieves 40
mpg without stop/start “SAE paper 10335
[2] Wikipedia, SkyActiv,
http://en.wikipedia.org/wiki/SkyActiv
[3] Mazda Global SKYACTIV TECHNOLOGY,
http://www.mazda.com/en/innovation/technology/skya
ctiv
[4] Mazda USA,
http://mazdausa.com/MusaWeb/microsite/skyactiv/#ho
me
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