FIELD OF INVENTION
The invention generally relates to internal combustion engine and more particularly to two-stroke internal combustion engine.
BACKGROUND
A two-stroke internal combustion engine takes in fresh air fuel charge and exhausts burned gas '
in every cycle as a part of producing power. This process of simultaneously purging exhaust
gas and filling the cylinder with fresh charge for a new cycle is referred to as scavenging. In
* . the conventional two-stroke internal combustion engine, the inner surface of-the cylinder is furnished with .an exhaust port -and a set of inlet ports, which are controlled with the
• reciprocating piston to open and close. After the power stroke of the two-stroke internal
1 combustion engine completes, the burnt gas in the cylinder is exhausted by means of gas
mixture entered into the.cylinder via the inlet ports. The scavenging process is characterized
by-two problems common to two-stroke engines in general: short-circuiting losses and mixing.
In short circuiting process, there is a mixing of fresh air fuel mixture with exhaust gases and
nearly 35% of fresh charges are lost through exhaust valve. Mixing consists on the fact that
there is a small amount of residual gases which remain trapped without being expelled, being
mixed with some of the new air charge. This leads to incomplete combustion emitting
significant amount of particulate matter, un-burnt hydrocarbons, carbon mono-oxide and Nitrous oxides. Conventional existing two stroke engines are well known to pollute badly and
their future will be limited due to excessive pollution.

Hence there is a need for a two-stroke engine design that can overcome one or more of the problems as set forth above.
SUMMARY OF THE INVENTION
According to an exemplary embodiment of the invention, a two-stroke internal combustion engine is disclosed. The two-stroke internal combustion engine includes a cylinder and a piston. - -The piston may be movable.axially inside the cylinder./fhe movement of the piston:maybe: ~ such that the piston reciprocates between an up-stroke to draw air into the cylinder and a down-stroke to compress anair-fuel mixture in the cylinder. The two-stroke-internal-combustion ■■ :engine furthers include at least one inlet valve provided on a bottom part of the cylinder. The • function.of the inlet valve-may be to allow air to flow into the cylinder. The two-stroke internal • - combustion engine further includes at least one exhaust port, provided on.a side wall of the cylinder in.proximity to a top part of the cylinder. The exhaust port may discharge the exhaust gas out of the cylinder.A fuel injector mounted in proximity to the bottom part of.the cylinder may be configured.to inject fuel into the cylinder. The fuel injector may be configured in such a way that the fuel is injected when the piston covers the exhaust port in the down-stroke.
BRIEF DESCRIPTION OF DRAWINGS
Other objects, features, and advantages of the invention will be apparent from the following description when read with reference to the accompanying drawings. In the drawings, wherein like reference numerals denote corresponding parts throughout the several views:

Figure 1 illustrates a twostroke internal combustion engine at the end of compression stroke according to an exemplary embodiment of the invention.
Figure 2 illustrates the. cylinder of figure 1 at near-end of expansion .stroke according to an exemplary embodiment of the invention.
Figure 3 illustrates the cylinder of figure 1 at the end. of expansion stroke according to an
exemplary-embodiment bf-theJnvention.: _
Figure 4 illustrates thecylinder of figure I at the start of compression stroke according to an
exemplary embodiment of the invention.
DETAILED DESCRIPTION OF DRAWINGS
The following description with reference to the accompanying drawings is provided to assist -in.a.comprehensive understanding of exemplary embodiments. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
According to an exemplary embodiment of the invention, a two-stroke internal combustion
OF Engine 100 is disclosed. The two-stroke internal combustion engine 100 includes a cylinder

102 and a.piston--104.arrangement. The cylinder 102 has a top part, a bottom part and a curved side wall.,The cylinder 102 and the piston 104 arrangement is such that the piston 104 is movable axially within the cylinder 102. This axial movement of the piston 104 includes reciprocating between an up-stroke to draw air into the cylinder 102 and a down-stroke to compress an air-fuel mixture in the cylinder 102.
The two-stroke internal combustion engine 100 further includes at least one inlet valve 106 opening provided on the bottom part of the.cyIinder-:|02. According4o^an-embodiment,the
two-stroke internal combustion engine 100 may include one inlet valve 106. According to -another embodiment; the number of inlet valves 106 provided on the cylinder 102 may depend
on the. dimensions of the inlet valves 106. The function ofthe inlet.valve 106 is to allow, air
without fuel into the cylinder 102.
The two-stroke internal combustion engine 100 further includes at least, one exhaust port 108 opening provided on the side wall ofthe cylinder 102 in proximity to the top part ofthe cylinder 102. According to an embodiment, the two-stroke internal combustion engine 100 may include one exhaust port 108. According to another embodiment, the number of exhaust ports 108 provided on the cylinder 102 may depend on the dimensions ofthe exhaust ports 108. The function ofthe exhaust port 108 in the two-stroke internal combustion engine 100 is to discharge an exhaust gas out ofthe cylinder 102 at the end of an expansion stroke.
The two-stroke internal combustion engine 100 further includes a fuel injector 110. The fuel injector 110 is mounted in proximity to the bottom part ofthe cylinder 102. The function ofthe
fuel injector 110 is to inject fuel 112 into the cylinder 102. The fuel injector 102 may be
"TfFP'IlTE CHENNAI IS -
configured in such a way that the fuel 112 is injected only when the piston 104 covers the

• exhaust.port'108 during the down stroke. The fuel injectoriUO.may: further be mounted in such a way that the fuel 112 is injected into the cylinder 102 in a direction against the gravity. The injection of fuel 112 against the gravity leads to a greater distribution inside the cylinder 102 and reduces deposition over the piston 104 head.
According to an embodiment, the two-stroke internal combustion engine 100 may include a
spark plug 1 l4;The spark plug 114 ignites the air-fuel mixture duringa compression stroke to
•--—generate power.-According-to an embodiment; the-spark plug-114-may be: used in a petrol - - --.-
•engine ora diesel engine to ignite the air-fuel mixture. According to another embodiment, the
air-fuel mixture.'in the diesel engine may ignite by.the.rise1 in> pressure and temperature ofthe
in the cylinder 102 during compression stroke.
According to an embodiment, the up-stroke in the two-stroke internal combustion engine 100 k is an expansion stroke and the down-stroke in the two-stroke internal combustion engine 100 is a'compression stroke.'The cylinder 102 and the piston 104 arrangement in the two-stroke internal combustion engine 100 is such that the piston 104 moves along gravity during the compression stroke and moves against gravity during the expansion stroke. The movement of the piston 104 within the cylinder 102 further controls the opening and closing ofthe exhaust port i08.
Figure I illustrates the two-stroke internal combustion engine 100 at. the end of compression stroke according to an exemplary embodiment of the invention. The piston 104 is in proximity to the bottom part ofthe cylinder 102. According to an embodiment, at this stage the spark plug ignites the air-fuel mixture for petrol and diesel engines. According to another embodiment, the air-fuel mixture ignites itself by the high pressure and temperature in diesel engines. The combustion of air-fuel mixture within the cylinder produces power along the expansion stroke.
Figure 2 illustrates the cylinder 104 of figure 1 at near-end of the expansion stroke according
to an exemplary embodiment of the invention. The piston 104 reciprocates from the bottom of
the cylinder 102 to the top of the cylinder 102 for the expansion stroke. As the piston 104
reciprocates to the top of the cylinder 102, the piston 104.uncovers the exhaust ports 108 provided1©-side;walls-in,proximity-to the top-part^of=the:cylinder:l04.^.The:exhaust gas-within
the cylinder 102 is on high pressure and so, move out of the cylinder 102 as the exhaust port
108 opens.1
Figure 3 illustrates the cylinder 102offigure I at the end of expansion stroke according to an
exemplary embodiment of the invention. The piston. 104. moves to top of the cylinder 102 by ..the end of the expansion stroke. When the piston 104 reaches thetop of the cylinder 102, the . .pressure inside the cylinder 102.drops below.the pressure at inlet. The pressure drop within the
cylinder 102.is.followed by opening of the inlet valves 106. The opening.of inlet valves 106 .
allows air without fuel into the cylinder 102 and the air pushes out the remaining exhaust gas
out of the cylinder 102 through the exhaust port 108.
Figure 4 illustrates the cylinder 102 of figure 1 at the start of the compression stroke according to an exemplary embodiment of the invention. The piston 104 moves from the top of the cylinder .102 to the bottom of the cylinder 102 for the compression stroke. As the piston 104 * moves to the bottom of the cylinder 102, the piston 104 covers the exhaust ports 108 and the
inlet valves 106 are closed due to pressure. At this stage, the fuel injector 1.10 is configured to inject fuel 112 within the cylinder.
It is understood that the above description is intended'to be illustrative, and not restrictive. It is intended to cover alt alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined in the appended claims. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description.
The scope of the invention should, therefore, be determined with reference to the appended
claims, along with the full scope of equivalents to-which such claims are entitled. In the
appended.-claims,, the-terms -'including" -and in-- which""are"used-as~the -plain-English .—--_equivalentsof the respective terms "comprising" and "wherein," respectively.

We claim:
1. A two-stroke internal combustion engine 100 comprising:
a cylinder 102;
a piston 104, movable axially within the cylinder 102, wherein the piston 104 reciprocates between an up-stroke to draw air into the cylinder 102 and a down-stroke to compress an air-fuel mixture in the cylinder 102;
at least one inlet valve 106 opening on a bottom part of the cylinder 104 to allow air without fuel into the cylinder 104;
.at least one exhaust port 108 opening out on a side wall of the cylinder 102 in proximity to a top part of the cylinder 102 to discharge an exhaust gas out of the cylinder 102; and
a fuel injector 110 mounted in proximity to the bottom part of the cylinder 104 and configured to inject fuel 112 into the cylinder 102, wherein the fuel 112 is injected when the piston 104 covers the exhaust port 108 in the down-stroke.
2. The two-stroke internal combustion engine 100 as claimed in claim 1, wherein the two-
stroke internal combustion engine 100 includes a spark plug to ignite the air-fuel
mixture in the cylinder 102.
- 3. The two-stroke internal combustion engine 100 as claimed in claim I, wherein the
0 F'FT'C E "T H E UN AI 2 7 f Cf 9 t 2 0 1 7 i 6 s 2 3 exhaust port 108 is opened and closed by the piston 102.

4. The two-stroke internal combustion engine 100 as claimed in claim 1, wherein the up¬stroke is the expansion stroke and the down-stroke is the compression stroke.
5. The two-stroke internal combustion engine 100 as claimed in claim 1, wherein the piston 104 moves along gravity during the compression stroke and against gravity during the expansion stroke.