FIELD OF INVENTION:
[001] The present subject matter described herein, relates to a piston for internal
combustion engine, and, in particular to, a piston bowl shape of the piston to
5 improve and maintain a tumble flow of intake air inside a cylinder.
BACKGROUND AND PRIOR ART:
[002] In internal combustion engines (hereinafter can be referred as “engines”)
an air-fuel mixture is combusted in a combustion chamber to generate power, a
tumble flow (vertical vortex flow) generated in a cylinder is effectively utilized to
10 increase the combustion efficiency of fuel, and thus improves the output, the
exhaust emission, the fuel consumption rate, and so forth. That is, the tumble flow
agitates inside the cylinder to promote evaporation and atomization of fuel,
achieving an excellent fuel property of fuel in the combustion chamber.
[003] In the past, various configurations have been purposed to improve the
15 tumble flow in the cylinder. Some configurations provide provisions in the air
intake manifold to improve the tumble flow. In another implementation, entry
angle of air fuel mixture in the cylinder, i.e., inlet angle and exit angle of air fuel
mixture in the cylinder, i.e., exit angle also plays important role in the tumble
flow.
20 [004] There is a need in the art to optimize other parameters of piston to obtain
improved tumble flow at center of the piston that is along bore axis of the
cylinder.
OBJECTS OF THE INVENTION:
[005] Some of the objects of the present disclosure, which at least one
25 embodiment herein satisfy, are listed hereinbelow.
[006] The principal object of the present invention is to provide a piston having
a piston bowl at piston crown to improve tumble flow to achieve improved flame
stability and combustion efficiency in internal combustion engine.
2
[007] Another object of the present invention is to provide a piston bowl with
optimized parameter to obtain the improved tumble flow along bore axis.
[008] Another object of the present invention is to provide a piston in the
internal combustion engine with port fuel injection to improve flame stability and
5 combustion efficiency.
[009] These and other objects and advantages will become more apparent when
reference is made to the following description and accompanying drawings.
SUMMARY OF THE INVENTION:
[0010] This summary is provided to introduce concepts related to piston of
10 internal combustion engine with port fuel injection. The concepts are further
described below in the detailed description. This summary is not intended to
identify key features or essential features of the claimed subject matter, nor is it
intended to be used to limit the scope of the claimed subject matter.
[0011] The present subject matter relates to a piston of an internal combustion
15 engine with port fuel injection to improve tumble flow in cylinder. The piston
comprises a body portion having a cylindrical shape and configured to reciprocate
within a cylinder bore having diameter (D) of the internal combustion engine. The
piston further comprises a crown portion coupled to the body portion. The crown
portion comprises a piston bowl having a substantial concave shape that is
20 contoured to be curved in a direction of a streamline of the vertical-vortex tumble
flow. The piston bowl having a flat portion at center where the piston bowl
defines a ratio (CD*) of a center flat diameter (107) of the piston bowl (102) to
the cylindrical bore diameter (D) is within a range 0.15 to 0.2 to maintain the
compression ratio in the cylinder.
25 [0012] In an aspect, a ratio (ROC*) of radius of curvature of the piston bowl to
the cylindrical bore diameter (D) is within a range 0.35 to 0.45 to sustain the
tumble for longer period of time in the piston bowl.
3
[0013] In an aspect, a ratio (PB*) of a piston blend of the piston bowl to the
cylindrical bore diameter (D) is within a range 0.35 to 0.45 to form diagonal
vortex near closing of the intake valve.
[0014] In an aspect, a ratio (PD*) of a piston depth of the piston bowl to the
5 cylindrical bore diameter (D) is within a range 0.05 to 0.15.
[0015] In an aspect, a ratio (PBD*) of a piston bowl diameter of the piston bowl
to the cylindrical bore diameter (D) is within a range 0.75 to 0.85.
[0016] In an aspect, a ratio (SL*) of a squish length of the piston bowl to the
cylindrical bore diameter (D) is within a range 0.15 to 0.25.
10 [0017] In an aspect, the squish length is flat portion in between the piston blend
and outer edge of the piston crown.
[0018] In an aspect, the internal combustion engine having port fuel injection.
[0019] To further understand the characteristics and technical contents of the
present subject matter, a description relating thereto will be made with reference
15 to the accompanying drawings. However, the drawings are illustrative only but
not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] It is to be noted, however, that the appended drawings illustrate only
typical embodiments of the present subject matter and are therefore not to be
20 considered for limiting of its scope, for the invention may admit to other equally
effective embodiments. The detailed description is described with reference to the
accompanying figures. In the figures, the left-most digit(s) of a reference number
identifies the figure in which the reference number first appears. The same
numbers are used throughout the figures to reference like features and
25 components. Some embodiments of system or methods in accordance with
embodiments of the present subject matter are now described, by way of example,
and with reference to the accompanying figures, in which:
4
[0021] Fig. 1 illustrates structure of piston crown or piston head of a piston
having piston bowl, in accordance with an embodiment of the present subject
matter;
[0022] Fig. 2 illustrates side view of piston crown of fig. 2, in accordance with an
5 embodiment of the present subject matter;
[0023] Fig. 3 illustrates relationship between tumble flow diameter and piston
bowl, in accordance with an embodiment of the present subject matter;
[0024] Fig. 4 illustrates continuous propagation of flame in all direction in all four
cycles, in accordance with an embodiment of the present subject matter;
10 [0025] Fig. 5a and 5b illustrate distance between the tumble center bore axis, in
accordance with an embodiment of the present subject matter; and
[0026] Fig. 6a and 6b illustrate comparison between base piston and the present
piston, in accordance with an embodiment of the present subject matter.
[0027] The figures depict embodiments of the present subject matter for the
15 purposes of illustration only. A person skilled in the art will easily recognize from
the following description that alternative embodiments of the structures and
methods illustrated herein may be employed without departing from the principles
of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
20 [0028] The detailed description of various exemplary embodiments of the
disclosure is described herein with reference to the accompanying drawings. It
should be noted that the embodiments are described herein in such details as to
clearly communicate the disclosure. However, the amount of details provided
herein is not intended to limit the anticipated variations of embodiments; on the
25 contrary, the intention is to cover all modifications, equivalents, and alternatives
falling within the scope of the present disclosure as defined by the appended
claims.
5
[0029] It is also to be understood that various arrangements may be devised that,
although not explicitly described or shown herein, embody the principles of the
present disclosure. Moreover, all statements herein reciting principles, aspects,
and embodiments of the present disclosure, as well as specific examples, are
5 intended to encompass equivalents thereof.
[0030] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of example embodiments. As
used herein, the singular forms “a",” “an” and “the” are intended to include the
plural forms as well, unless the context clearly indicates otherwise. It will be
10 further understood that the terms “comprises,” “comprising,” “includes” and/or
“including,” when used herein, specify the presence of stated features, integers,
steps, operations, elements and/or components, but do not preclude the presence
or addition of one or more other features, integers, steps, operations, elements,
components and/or groups thereof.
15 [0031] It should also be noted that in some alternative implementations, the
functions/acts noted may occur out of the order noted in the figures. For example,
two figures shown in succession may, in fact, be executed concurrently or may
sometimes be executed in the reverse order, depending upon the functionality/acts
involved.
20 [0032] Unless otherwise defined, all terms (including technical and scientific
terms) used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which example embodiments belong. It will be further
understood that terms, e.g., those defined in commonly used dictionaries, should
be interpreted as having a meaning that is consistent with their meaning in the
25 context of the relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0033] These and other advantages of the present subject matter would be
described in greater detail with reference to the following figures. It should be
noted that the description merely illustrates the principles of the present subject
30 matter. It will thus be appreciated that those skilled in the art will be able to devise
6
various arrangements that, although not explicitly described herein, embody the
principles of the present subject matter and are included within its scope.
[0034] Fig. 2 illustrates structure of piston of internal combustion engine with
optimized parameters to improve tumble flow in the internal combustion chamber
5 with port fuel injection, in accordance with an embodiment of the present subject
matter. As shown in figure 2, the piston 100 comprise a body portion having a
cylindrical shape and configured to reciprocate within a cylinder bore having
diameter (D) of the internal combustion engine. Further, the piston 100 comprise a
piston head portion 101 or a crown portion 101 coupled to the body portion. The
10 crown portion 101 further comprises a piston bowl 102 (or depression) having a
substantial concave shape that is contoured to be curved in a direction of a
streamline of the vertical-vortex tumble flow.
[0035] Referring to fig. 1 and 2, the present piston bowl 102 has a plurality of
optimized parameters to obtain a stable and improved tumble flow in the cylinder.
15 The piston bowl 102 defines a radius of curvature 103 in the concave shape
profile of the piston bowl. The radius of curvature 103 facilitates to sustain the
tumble flow for a longer period of time and be contained in the piston bowl 102
for vertical vortex. The piston bowl 102 is dimensioned so that a ratio (ROC*) of
radius of curvature 103 of the piston bowl 102 to the cylindrical bore diameter (D)
20 is within a range 0.35 to 0.45. Further, the ratio (ROC*) is large so that the tumble
can be sustained for longer period of time and be remained in the piston bowl 102.
[0036] The piston bowl 102 defines piston blend 104 that is immediately above
the radius of curvature 103 toward circumference of the crown portion 101. The
piston blend 104 helps in formation of diagonal vortex near the closing of intake
25 valve. The piston bowl 102 is dimensioned so that a ratio (PB*) of a piston blend
104 of the piston bowl 102 to the cylindrical bore diameter (D) is within a range
0.35 to 0.45. The piston blend is a curvature and Piston Blend is radius of
curvature of blend. To avoid ambiguity, Piston Blend Radius is written instead of
Piston blend alone.
7
[0037] The piston bowl 102 defines a piston depth 105 to sustain tumble flow as
well contain the tumble flow inside the piston bowl 102. The piston depth 105 is
kept maximum as it is constrained with material strength and durability. The
piston bowl 102 is dimensioned so that a ratio (PD*) of a piston depth (105) of the
5 piston bowl (102) to the cylindrical bore diameter (D) is within a range 0.05 to
0.15.
[0038] The piston bowl 102 has a piston bowl diameter 106 to create a larger
diameter tumble flow in the cylinder. As can be seen from the fig. 4, the tumble
flow diameter 200 directly depends on the diameter of the piston bowl. The piston
10 bowl 102 is dimensioned so that a ratio (PBD*) of a piston bowl diameter (106) of
the piston bowl (102) to the cylindrical bore diameter (D) within a range of 0.75
to 0.85.
[0039] The piston bowl 102 has a flat portion 107 at center of the piston crown
101. The flat portion 107 is provided to keep the required compression ratio (CR)
15 in the cylinder. The piston bowl 102 is dimensioned so that a ratio (CD*) of a
center flat diameter (107) of the piston bowl (102) to the cylindrical bore diameter
(D) is within a range of 0.15 to 0.2.
[0040] The piston bowl 102 has a squish portion 108 immediately after the piston
blend 104 and extends up to edge of the circumference of the crown portion 101.
20 Where length of the squish portion 108 depends on the cylinder head. The squish
portion 108 provided to increase squish velocity towards spark plug of the
cylinder (combustion chamber which is defined by cylinder head cylinder bore
and piston crown) enabling more fuel air mixture to take part in combustion in the
combustion chamber. The piston bowl 102 is dimensioned so that a ratio (SL*) of
25 a squish length of the squish portion (108) of the piston bowl (102) to the
cylindrical bore diameter (D) is within a range of 0.15 to 0.25.
[0041] Referring to fig. 3, the tumble flow diameter 200 depends on the
parameters as explained above in reference to fig. 1 and 2. More the optimized
parameters, more improved tumble flow will be achieved.
30 [0042] With the present optimized parameters of the piston bowl 102, center of
the tumble flow can be obtained closest to bore axis near the end of the
8
compression stroke. Referring to fig. 4, the present piston bowl with optimized
parameters enables the stability of flame and increases combustion efficiency.
Further, the present piston bowl enables the flame in the combustion chamber to
propagate continuously in all the four cycles as shown in fig. 4. The continuous
5 propagation of the flame leads to increased flame stability and combustion
efficiency.
[0043] As shown in the fig. 5a and 5b, in the present piston 100, the tumble
center/bore diameter is obtained 0.10 away from the bore axis near the end of
compression stroke as shown in fig. 5a which is much nearer to Base (0.22) as
10 shown in Fig. 5b.
[0044] Fig. 6a illustrates the comparison between the base piston and the present
piston in reference to tumble center/bore diameter from the bore axis as shown in
fig. 5a and 5b. With the present graph as shown in the fig. 6a, the tumble
center/bore diameter is nearer to the bore axis as compared the base piston. With
15 the nearer tumble center/bore diameter, as shown in fig. 6b, the combustion
chamber having the present piston has more flame stability as compared to the
combustion chamber having base piston.
[0045] It will be understood by those within the art that, in general, terms used
herein, and especially in the appended claims (e.g., bodies of the appended
20 claims) are generally intended as “open” terms (e.g., the term “including” should
be interpreted as “including but not limited to,” the term “having” should be
interpreted as “having at least,” the term “includes” should be interpreted as
“includes but is not limited to,” etc.). It will be further understood by those within
the art that if a specific number of an introduced claim recitation is intended, such
25 an intent will be explicitly recited in the claim, and in the absence of such
recitation no such intent is present. For example, as an aid to understanding, the
following appended claims may contain usage of the introductory phrases “at least
one” and “one or more” to introduce claim recitations. However, the use of such
phrases should not be construed to imply that the introduction of a claim recitation
30 by the indefinite articles “a” or “an” limits any particular claim containing such
introduced claim recitation to inventions containing only one such recitation, even
9
when the same claim includes the introductory phrases “one or more” or “at least
one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should
typically be interpreted to mean “at least one” or “one or more”); the same holds
true for the use of definite articles used to introduce claim recitations. In addition,
5 even if a specific number of an introduced claim recitation is explicitly recited,
those skilled in the art will recognize that such recitation should typically be
interpreted to mean at least the recited number (e.g., the bare recitation of “two
recitations,” without other modifiers, typically means at least two recitations, or
two or more recitations). Furthermore, in those instances where a convention
10 analogous to “at least one of A, B, and C, etc.” is used, in general such a
construction is intended in the sense one having skill in the art would understand
the convention (e.g., “a system having at least one of A, B, and C” would include
but not be limited to systems that have A alone, B alone, C alone, A and B
together, A and C together, B and C together, and/or A, B, and C together, etc.).
15 In those instances where a convention analogous to “at least one of A, B, or C,
etc.” is used, in general such a construction is intended in the sense one having
skill in the art would understand the convention (e.g., “a system having at least
one of A, B, or C” would include but not be limited to systems that have A alone,
B alone, C alone, A and B together, A and C together, B and C together, and/or A,
20 B, and C together, etc.). It will be further understood by those within the art that
virtually any disjunctive word and/or phrase presenting two or more alternative
terms, whether in the description, claims, or drawings, should be understood to
contemplate the possibilities of including one of the terms, either of the terms, or
both terms. For example, the phrase “A or B” will be understood to include the
25 possibilities of “A” or “B” or “A and B.”
[0046] While the foregoing describes various embodiments of the invention, other
and further embodiments of the invention may be devised without departing from
the basic scope thereof. The scope of the invention is determined by the claims
that follow. The invention is not limited to the described embodiments, versions
30 or examples, which are included to enable a person having ordinary skill in the art
10
to make and use the invention when combined with information and knowledge
available to the person having ordinary skill in the art.

We claim:
1. A piston (100) for use in an internal combustion engine, the piston (100)
comprising:
a body portion having a cylindrical shape and configured to
5 reciprocate within a cylinder bore having diameter (D) of the internal
combustion engine; and
a crown portion (101) coupled to the body portion, the crown
portion (101) comprises a piston bowl (102) having a substantial concave
shape that is contoured to be curved in a direction of a streamline of the
10 vertical-vortex tumble flow,
characterized in that
the piston bowl (102) defining a flat portion (107) at center;
a radius of curvature (103);
a piston blend (104);
15 a piston bowl diameter (106);
a piston depth (105); and
a squish portion (108).
2. The piston (100) as claimed in claim 1, wherein a ratio (CD*) of a center
20 flat diameter (CD) of the flat portion (107) of the piston bowl (102) to the
cylindrical bore diameter (D) is within a range of 0.15 to 0.2.
3. The piston (100) as claimed in claim 1, wherein a ratio (ROC*) of radius
of curvature (103) of the piston bowl (102) to the cylindrical bore diameter
(D) is within a range of 0.35 to 0.45.
25 4. The piston (100) as claimed in claim 1, wherein a ratio (PB*) of a piston
blend (104) of the piston bowl (102) to the cylindrical bore diameter (D) is
within a range of 0.35 to 0.45.
5. The piston (100) as claimed in claim 1, wherein a ratio (PD*) of a piston
depth (105) of the piston bowl (102) to the cylindrical bore diameter (D) is
30 within a range of 0.05 to 0.15.
12
6. The piston (100) as claimed in claim 1, wherein a ratio (PBD*) of a piston
bowl diameter (106) of the piston bowl (102) to the cylindrical bore
diameter (D) is within a range of 0.75 to 0.85.
7. The piston (100) as claimed in claim 1, wherein a ratio (SL*) of a squish
5 length of a squish portion (108) of the piston bowl (102) to the cylindrical
bore diameter (D) is within a range of 0.15 to 0.25.
8. The piston (100) as claimed in claim 1, wherein the squish length (108) is
flat portion in between the piston blend (104) and outer edge of the piston
crown (101).
10 9. The piston (100) as claimed in claim 1, wherein the internal combustion
engine having port fuel injection.