U.S. patent application number 10/060663 was filed with the patent office on 2003-07-31 for combustion chamber.
Invention is credited to Gui, Xinqun, Liu, Zhengbai.
Application Number | 20030140890 10/060663 |
Document ID | / |
Family ID | 27610062 |
Filed Date | 2003-07-31 |
United States Patent
Application |
20030140890 |
Kind Code |
A1 |
Liu, Zhengbai ; et
al. |
July 31, 2003 |
COMBUSTION CHAMBER
Abstract
A combustion chamber assembly for use in a diesel engine
includes a combustion chamber being defined in a crown of a piston,
the combustion chamber having a center portion, the center portion
being defined at least in part by a portion of a convex sphere to
define a post, the sphere having a radius and an origin, the origin
of the radius lying on a combustion chamber central axis and the
combustion chamber further having an outwardly radially disposed
bottom margin, the bottom margin being defined in part by a portion
of a sphere, the sphere being concave and having an origin and a
radius. The combustion chamber has more than two spherical surfaces
having smooth annular transitions between adjacent spherical
surfaces, the spherical surfaces including the spherical center
portion and the spherical bottom margin. A piston and a method of
forming a combustion chamber are further included.
Inventors: |
Liu, Zhengbai; (Lisle,
IL) ; Gui, Xinqun; (Lisle, IL) |
Correspondence
Address: |
INTERNATIONAL ENGINE INTELLECTUAL PROPERTY COMPANY
4201 WINFIELD ROAD
P.O. BOX 1488
WARRENVILLE
IL
60555
US
|
Family ID: |
27610062 |
Appl. No.: |
10/060663 |
Filed: |
January 30, 2002 |
Current U.S.
Class: |
123/279 |
Current CPC
Class: |
Y02T 10/12 20130101;
F02B 23/0672 20130101; Y02T 10/125 20130101; F02B 3/06
20130101 |
Class at
Publication: |
123/279 |
International
Class: |
F02F 003/26 |
Claims
What is claimed is:
1. A combustion chamber assembly for use in a diesel engine,
comprising: a combustion chamber being defined in a crown of a
piston, the combustion chamber having a center portion, the center
portion being defined at least in part by a portion of a convex
sphere to define a post, the sphere having a radius and an origin,
the origin of the radius lying on a combustion chamber central axis
and the combustion chamber further having an outwardly radially
disposed bottom margin, the bottom margin being defined in part by
a portion of a sphere, the sphere being concave and having an
origin and a radius; and the combustion chamber having more than
two spherical surfaces having smooth annular transitions between
adjacent spherical surfaces, the spherical surfaces including the
spherical center portion and the spherical bottom margin.
2. The combustion chamber assembly of claim 1 wherein the origins
of the post and the lower sidewall spherical surfaces are
co-centric and lie on the center axis of the combustion
chamber.
3. The combustion chamber assembly of claim 2 wherein the side wall
portion of the combustion chamber is substantially defined by two
spherical surfaces.
4. The combustion chamber assembly of claim 3 wherein the two
spherical surfaces substantially defining the side wall portion of
the combustion are joined by an annular surface.
5. The combustion chamber assembly of claim 3 wherein a one of the
two spherical surfaces substantially defining the higher side wall
portion of the combustion is transitioned by an annular surface to
a piston crown.
6. The combustion chamber assembly of claim 1 wherein the ratio of
the radius of the center portion convex spherical surface, RS1, of
the combustion chamber to the piston diameter, D1, is greater than
0.05 and less than 0.35.
7. The combustion chamber assembly of claim 6 wherein the ratio of
the radius of the center portion convex spherical surface, RS1, of
the combustion chamber to the piston diameter, D1, is substantially
0.18.
8. The combustion chamber assembly of claim 1 wherein the ratio of
the combustion chamber diameter D2 to the piston diameter D1 is
greater than 0.43 and less than 0.83.
9. The combustion chamber assembly of claim 8 wherein the ratio of
the combustion chamber diameter D2 to the piston diameter D1 is
preferably substantially 0.637.
10. The combustion chamber assembly of claim 1 wherein the ratio of
the diameter of the reentrancy D3 to the piston diameter D1 is
greater than 0.33 and less than 0.83.
11. The combustion chamber assembly of claim 10 wherein the ratio
of the diameter of the reentrancy D3 to the piston diameter D1 is
substantially 0.548.
12. The combustion chamber assembly of claim 1 wherein the ratio of
the radius of the center convex spherical surface RS1 to the
diameter of the piston D1 is greater than 0.05 and less than
0.35.
13. The combustion chamber assembly of claim 12 wherein the ratio
of the radius of the center convex spherical surface RS1 to the
diameter of the piston D1 is substantially 0.018.
14. The combustion chamber assembly of claim 1 wherein the ratio of
the spherical surface RS2 to the diameter of the piston D1 is
between 0.23 and 0.53.
15. The combustion chamber assembly of claim 14 wherein the ratio
of the spherical surface RS2 to the diameter of the piston D1 is
preferably substantially 0.334.
16. The combustion chamber assembly of claim 1 wherein the ratio of
the spherical surface RS3 to the diameter of the piston D1 is
between 1.18 and 4.18.
17. The combustion chamber assembly of claim 16 wherein the ratio
of the spherical surface RS3 to the diameter of the piston D1 is
preferably substantially 2.18.
18. The combustion chamber assembly of claim 1 wherein the ratio of
the spherical surface RS4 to the diameter of the piston D1 is
between 0.18 and 0.38.
19. The combustion chamber assembly of claim 18 wherein the ratio
of the spherical surface RS4 to the diameter of the piston D1 is
preferably substantially 0.28.
20. The combustion chamber assembly of claim 1 wherein the ratio of
the depth dimension of the combustion chamber H1 to the diameter D1
of the piston is greater than 0.1 and less than 0.4.
21. The combustion chamber assembly of claim 20 wherein the ratio
of the distance H1 to the diameter D1 of the piston is preferably
substantially 0.2.
22. The combustion chamber assembly of claim 1 wherein the ratio of
the certain distance H2, H2 being the post height distance from a
peak of the center portion convex spherical surface to the bottom
plane of the combustion chamber, to the diameter D1 of the piston
is greater than 0.04 and less than 0.24.
23. The combustion chamber assembly of claim 22 wherein the ratio
of the certain distance H2 to the diameter D1 is preferably
substantially 0.144.
24. The combustion chamber assembly of claim 1 wherein the radius
of the annular surface R1 is equal to the radius of the annular
surface R2.
25. The combustion chamber assembly of claim 1 wherein the ratio of
the annular surface radius R1 to the diameter of the piston D1 and
the annular surface R2 to the diameter D1 are each greater than
0.03 and less than 0.25.
26. The combustion chamber assembly of claim 25 wherein the ratio
of the annular sidewall surface radius R1 to the diameter of the
piston D1 and the annular surface R2 to the diameter D1 are each
preferably substantially 0.051.
27. The combustion chamber assembly of claim 1 wherein the ratio of
the annular surface radius R3 to the diameter of the piston D1 and
the ratio of the annular surface radius R4 to the diameter of the
piston D1 are each greater than 0.0 and less than 0.1.
28. The combustion chamber assembly of claim 1 wherein the distance
between the co-center of the spherical surfaces RS1, RS2 and the
point of intersection of a combustion chamber axis with a bottom
plane of the combustion chamber is less than 0.28 the piston
diameter D1.
29. The combustion chamber assembly of claim 28 wherein the
distance between the co-center of the spherical surfaces RS1, RS2
and the point of intersection of a combustion chamber axis with a
bottom plane of the combustion chamber is preferably 0.073 D1
30. The combustion chamber assembly of claim 1 wherein the origin
of a spherical surface RS3 is on a central axis of the combustion
chamber.
31. The combustion chamber assembly of claim 30 wherein the
distance between the origin of the spherical surface RS3 and a
point of intersection of the central axis of the combustion chamber
with a bottom plane of the combustion chamber is greater than 0.75
the piston diameter D1 and less than 3.0 D1.
32. The combustion chamber assembly of claim 31 wherein the
distance between the origin of the spherical surface RS3 and the
point of intersection of the central axis of the combustion chamber
with the bottom plane of the combustion chamber is preferably 2.178
D1.
33. The combustion chamber assembly of claim 1 wherein the origin
of a spherical surface RS4 is on a combustion chamber central axis
and the distance between the origin of the spherical surface RS4
and a point of intersection of the central axis of the combustion
chamber with a top plane of the combustion chamber is the height H3
greater than 0.02 the piston diameter D1 and less than 0.42 D1.
34. The combustion chamber assembly of claim 33 wherein the ratio
of the height H3 to the diameter of the piston D1 is greater than
0.02 and less than 0.42.
35. The combustion chamber assembly of claim 34 wherein the ratio
of the height H3 to the diameter of the piston D1 is preferably
substantially 0.051.
36. The combustion chamber assembly of claim 1 the combustion
chamber having a central axis, the combustion chamber central axis
being coincident with a piston central axis.
37. The combustion chamber assembly of claim 1 the combustion
chamber having a central axis, the combustion chamber central axis
being offset from a piston central axis.
38. The combustion chamber assembly of claim 37 the combustion
chamber having a central axis, the combustion chamber central axis
being offset from the piston central axis less than a distance
equal to 0.1 the piston diameter D1.
39. The combustion chamber assembly of claim 1 being formed free of
flat surfaces.
40. A piston for use in a diesel engine, the piston having a
central axis, comprising: a combustion chamber being defined in a
crown of the piston, the combustion chamber having a center
portion, the center portion being defined at least in part by a
portion of a convex sphere to define a post, the sphere having a
radius and an origin, the origin of the radius lying on a
combustion chamber central axis and the combustion chamber further
having an outwardly radially disposed bottom margin, the bottom
margin being defined in part by a portion of a sphere, the sphere
being concave and having an origin and a radius; and the combustion
chamber having more than two spherical surfaces having smooth
annular transitions between adjacent spherical surfaces, the
spherical surfaces including the spherical center portion and the
spherical bottom margin.
41. The piston of claim 40 wherein the origin of the post and the
lower sidewall spherical surfaces are co-centric and lie on the
center axis of the combustion chamber.
42. The piston of claim 41 wherein the side wall portion of the
combustion chamber is substantially defined by two spherical
surfaces.
43. The piston of claim 42 wherein the two spherical surfaces
substantially defining the side wall portion of the combustion
chamber are joined by an annular surface.
44. The piston of claim 42 wherein a one of the two spherical
surfaces substantially defining the higher side wall portion of the
combustion is transitioned by an annular surface to a piston
crown.
45. The piston of claim 40 wherein the ratio of the radius of the
center portion convex spherical surface, RS1, of the combustion
chamber to the piston diameter, D1, is greater than 0.05 and less
than 0.35.
46. The piston of claim 45 wherein the ratio of the radius of the
center portion convex spherical surface, RS1, of the combustion
chamber to the piston diameter, D1, is substantially 0.18.
47. The piston of claim 40 wherein the ratio of the combustion
chamber diameter D2 to the piston diameter D1 is greater than 0.43
and less than 0.83.
48. The piston of claim 47 wherein the ratio of the combustion
chamber diameter D2 to the piston diameter D1 is preferably
substantially 0.637.
49. The piston of claim 40 wherein the ratio of the diameter of the
reentrancy D3 to the piston diameter D1 is greater than 0.33 and
less than 0.83.
50. The piston of claim 49 wherein the ratio of the diameter of the
reentrancy D3 to the piston diameter D1 is substantially 0.548.
51. The piston of claim 40 wherein the ratio of the radius of the
center convex spherical surface RS1 to the diameter of the piston
D1 is greater than 0.05 and less than 0.35.
52. The piston of claim 51 wherein the ratio of the radius of the
center convex spherical surface RS1 to the diameter of the piston
D1 is substantially 0.018.
53. The piston of claim 40 wherein the ratio of the spherical
surface RS2 to the diameter of the piston D1 is between 0.23 and
0.53.
54. The piston of claim 53 wherein the ratio of the spherical
surface RS2 to the diameter of the piston D1 is preferably
substantially 0.334.
55. The piston of claim 40 wherein the ratio of the spherical
surface RS3 to the diameter of the piston D1 is between 1.18 and
4.18.
56. The piston of claim 55 wherein the ratio of the spherical
surface RS3 to the diameter of the piston D1 is preferably
substantially 2.18.
57. The piston of claim 40 wherein the ratio of the spherical
surface RS4 to the diameter of the piston D1 is between 0.18 and
0.38.
58. The piston of claim 57 wherein the ratio of the spherical
surface RS4 to the diameter of the piston D1 is preferably
substantially 0.28.
59. The piston of claim 40 wherein the ratio of the depth dimension
of the combustion chamber H1 to the diameter D1 of the piston is
greater than 0.1 and less than 0.4.
60. The piston of claim 59 wherein the ratio of the distance H1 to
the diameter D1 of the piston is preferably substantially 0.2.
61. The piston of claim 40 wherein the ratio of the certain
distance H2, H2 being the post height distance from a peak of the
center portion convex spherical surface to the bottom plane of the
combustion chamber, to the diameter D1 of the piston is greater
than 0.04 and less than 0.24.
62. The piston of claim 61 wherein the ratio of the certain
distance H2 to the diameter D1 is preferably substantially
0.144.
63. The piston of claim 40 wherein the radius of the annular
surface R1 is equal to the radius of the annular surface R2.
64. The piston of claim 40 wherein the ratio of the annular surface
radius R1 to the diameter of the piston D1 and the ratio of the
annular surface R2 to the diameter D1 are each greater than 0.03
and less than 0.25.
65. The piston of claim 64 wherein the ratio of the annular surface
radius R1 to the diameter of the piston D1 and the annular surface
R2 to the diameter D1 are each preferably substantially 0.051.
66. The piston of claim 40 wherein the ratio of the annular surface
radius R3 to the diameter of the piston D1 and the ratio of the
annular surface radius R4 to the diameter of the piston D1 are each
greater than 0.0 and less than 0.1.
67. The piston of claim 40 wherein the distance between the
co-center of the spherical surfaces RS1, RS2 and the point of
intersection of a combustion chamber axis with a bottom plane of
the combustion chamber is less than 0.28 the piston diameter
D1.
68. The piston of claim 67 wherein the distance between the
co-center of the spherical surfaces RS1, RS2 and the point of
intersection of a combustion chamber axis with the bottom plane of
the combustion chamber is preferably 0.073 D1
69. The piston of claim 40 wherein the origin of a spherical
surface RS3 is on a central axis of the combustion chamber.
70. The piston of claim 69 wherein the distance between the origin
of the spherical surface RS3 and a point of intersection of the
central axis of the combustion chamber with a bottom plane of the
combustion chamber is greater than 0.75 the piston diameter D1 and
less than 3.0 D1.
71. The piston of claim 70 wherein the distance between the origin
of the spherical surface RS3 and the point of intersection of the
central axis of the combustion chamber with the bottom plane of the
combustion chamber is preferably 2.178 D1.
72. The piston of claim 40 wherein the origin of a spherical
surface RS4 is on a combustion chamber central axis and the
distance between the origin of the spherical surface RS4 and a
point of intersection of the central axis of the combustion chamber
with a top plane of the combustion chamber is the height H3 greater
than 0.02 the piston diameter D1 and less than 0.42 D1.
73. The piston of claim 72 wherein the ratio of the height H3 to
the diameter of the piston D1 is greater than 0.02 and less than
0.42.
74. The piston of claim 73 wherein the ratio of the height H3 to
the diameter of the piston D1 is preferably substantially
0.051.
75. The piston of claim 40, the combustion chamber having a central
axis, the combustion chamber central axis being coincident with a
piston central axis.
76. The piston of claim 40, the combustion chamber having a central
axis, the combustion chamber central axis being offset from a
piston central axis.
77. The piston of claim 76, the combustion chamber having a central
axis, the combustion chamber central axis being offset from the
piston central axis less than a distance equal to 0.1 the piston
diameter D1.
78. The piston of claim 40, the combustion chamber being formed
free of flat surfaces.
79. A method of forming a combustion chamber for use in a piston of
a diesel engine, comprising: defining a combustion chamber in a
crown of a piston, the piston having a central axis, the combustion
chamber being formed by: defining a combustion chamber elevated
center portion; defining the center portion at least in part by a
portion of a convex sphere, the sphere having a radius, defining a
combustion chamber bottom margin in part by a concave spherical
surface, the concave spherical surface having a radius; and
defining a plurality of combustion chamber spherical surfaces
having smooth transitions between adjacent spherical surfaces, the
spherical surfaces including at least the convex spherical center
portion, the concave spherical bottom margin surface.
80. The method of claim 79 including defining the combustion
chamber by a plurality of spherical surfaces and a plurality of
annular surfaces.
81. The method of claim 80 including defining the combustion
chamber by four spherical surfaces and adjoining annular
surfaces.
82. The method of claim 79 including disposing the respective
origins of the convex spherical center portion and the spherical
lower sidewall surfaces co-centrically.
83. The method of claim 79 including forming the combustion chamber
free of flat surfaces.
84. The method of claim 79 including displacing a combustion
chamber central axis in a parallel relationship with a piston
central axis.
85. The method of claim 79 including disposing a combustion chamber
central axis co-linear with a piston central axis.
Description
TECHNICAL FIELD
[0001] The present invention relates to a piston designed for use
in a compression ignition (diesel) internal combustion engine. More
particularly, the present invention relates to a combustion chamber
defined in the crown of a piston.
BACKGROUND OF THE INVENTION
[0002] Many attempts have been made to produce an ideal flow
pattern for the charge of air and fuel within the combustion
chamber of an internal combustion engine. Considerations that must
be taken into effect include, but are not limited to, providing for
adequate power generation minimizing the NOx entrained in the
engine exhaust and minimizing the amount of soot particulate also
entrained in the engine exhaust. This should be accomplished
without hurting the fuel economy of the engine and without
adversely affecting the power output of the engine.
[0003] It is known that changes in any one of a variety of engine
design/operating variables, such as engine compression, combustion
chamber shape, fuel injection spray pattern, and other variables
can have an effect on both emissions and power generated.
[0004] The amount of soot that is expelled with the engine's
exhaust is unsightly and generates public pressure to clean up
diesel engines. Further, the amount of soot that is entrained in
the engine's lubrication oil can have a deleterious effect on
engine reliability. Soot is very abrasive and can cause high engine
wear.
[0005] There is additionally a great deal of pressure to reduce the
NOx emissions from the engine. Ever increasing regulatory demands
mandate reduced levels of NOx Typically, a combustion chamber
design that is effective at reducing NOx levels has been found to
increase the levels of soot and vice-versa. Additionally, doing
either of the aforementioned typically reduces engine torque and
power outputs.
[0006] There are numerous examples of combustion chambers formed in
the crown of piston. Notwithstanding all these prior art designs,
there remains a need for reduction both in NOx and entrained soot
while at the same time maintaining or enhancing engine torque and
power outputs without adversely affecting the fuel economy of the
engine.
SUMMARY OF THE INVENTION
[0007] The piston of the present invention substantially meets the
aforementioned needs of the industry. The combustion chamber of the
present invention defined in the crown of the piston has been shown
by substantiated simulation to both reduce soot entrainment and NOx
emissions while at the same time maintaining engine power output.
The piston has been shown to function effectively with cylinder
heads having two or more valves. A further advantage of the piston
of the present invention is that by being symmetrical with respect
to a piston central axis, the combustion chamber is relatively
easily formed in the crown of the piston. The piston and combustion
chamber of the present invention are preferably used in heavy-duty
and medium-duty diesel engines.
[0008] The present invention is a combustion chamber assembly for
use in a diesel engine and includes a combustion chamber being
defined in a crown of a piston, the combustion chamber having a
center portion, the center portion being defined at least in part
by a portion of a convex sphere to define a post, the sphere having
a radius and an origin, the origin of the radius lying on a
combustion chamber central axis and the combustion chamber further
having an outwardly radially disposed bottom margin, the bottom
margin being defined in part by a portion of a sphere, the sphere
being concave and having an origin and a radius. The combustion
chamber has more than two spherical surfaces having smooth annular
transitions between adjacent spherical surfaces, the spherical
surfaces including the spherical center portion and the spherical
bottom margin. A piston and a method of forming a combustion
chamber are further included. The present invention is further a
piston incorporating the aforementioned combustion chamber and a
method of forming the combustion chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a sectional view of the piston and combustion
chamber of the present invention;
[0010] FIG. 2 is a graphic representation of NOx generated with
respect to crank angle of empirical data of a prior art engine, B0,
a simulation, B0 of the same engine to substantiate the validity of
the simulation, substantially overlying the empirical data, and a
simulation of an engine with pistons and combustion chambers of the
present invention, B27; and
[0011] FIG. 3 is a graphic representation of the soot generated by
the prior art B0 piston and combustion chamber as compared to the
piston and combustion chamber of the present invention, B27.
DETAILED DESCRIPTION OF THE DRAWINGS
[0012] The piston of the present invention is shown generally at 10
in FIG. 1. Generally, the piston 10 has a centrally located
symmetrical upward directed cavity for forming a portion of a
combustion chamber 12 within a cylinder of a diesel engine. The
combustion chamber 12 is defined in the crown 14 of the piston 10.
The engine has a fuel injector for forming a fuel injection plume
relative to the combustion chamber 12. The piston 10 may be
utilized with two-valve or multiple-valve heads. The piston 10 is
effective at reducing diesel engine pollutant emissions, such as
NOx and soot, as depicted in the graphic representations of FIGS. 2
and 3. The piston 10 is preferably applicable to heavy-duty and
medium duty diesel engines.
[0013] The piston 10 has a symmetrical upwardly opening cavity for
forming a major part of a combustion chamber 12 within a cylinder
of a diesel engine having a fuel injector for forming a fuel
injection plume in order to reduce diesel engine pollutant
emissions such as NOx and soot without hurting the fuel economy and
power output.
[0014] The combustion chamber 12 located in the piston crown 14 of
diesel engines and mainly comprises a portfolio of spherical
surfaces, as shown in FIG. 1. Two spherical surfaces, RS1 and RS2,
with a co-center 16 lying on the chamber axis 18 form the major
part of the combustion chamber 12. The inner spherical surface RS1
is located at the central bottom of the combustion chamber 12 to
form a post 20 and has a radius of RS1. The outer spherical surface
RS2 forms the lower part of the sidewall of the combustion chamber
12 and has a radius of RS2. A third spherical surface RS3, having a
radius of RS3, forms the outer bottom margin of the combustion
chamber 12. A fourth spherical surface RS4 has a radius of RS4 and
forms the higher part of the sidewall of the combustion chamber
12.
[0015] Four small annular surfaces R1-R4 function as connection and
transition between adjacent spherical surfaces and with the crown
14. The inner spherical surface RS1 and the outer bottom spherical
surface RS3 are connected by an annular surface that has a radius
of R1. The lower sidewall spherical surface RS2 and the outer
bottom spherical surface RS3 are connected by an annular surface
that has a radius of R2. The lower sidewall spherical surface RS2
and the higher sidewall spherical surface RS4 are connected by an
annular surface that has a radius of R3. The higher sidewall
spherical surface RS4 transits to or reenters the piston crown 14
through a small annular surface R4 that has a radius of R4.
[0016] The origins of spherical surfaces RS1 and RS2 are in
coincidence with each other, that is, they have a co-center 16, and
the co-center 16 is located on the central axis 18 of the
combustion chamber 12. The distance between the co-center 16 of
spherical surfaces RS1 and RS2 and the point of intersection of the
combustion chamber axis 18 with the bottom plane 22 of the
combustion chamber is equal to or greater than zero and is less
than 0.28 D1, D1 being the piston diameter, and is preferably 0.073
D1. The origin of the spherical surface RS3 is on the central axis
18 of the combustion chamber, and the distance between the origin
of spherical surface RS3 and the point of intersection of the
combustion chamber axis 18 with the bottom of the plane 22 of the
combustion chamber 12 is greater than 0.75 D1 and less than 3.0 D1,
and is preferably 2.178 D1. The origin of the spherical surface RS4
is on the central axis 18 of the combustion chamber 12, and the
distance between the origin of spherical surface RS4 and the point
of intersection of the combustion chamber axis 18 with the crown 14
of the piston 10 is equal to H3. The ratio of H3/D1 is greater than
0.02 and is less than 0.42, and is preferably 0.051.
[0017] The central axis 18 of the combustion chamber 12 can
coincide with the central axis 24 of the piston 10 or has an
offset, that is the distance H4 between the central axis 18 of the
combustion chamber 12 and the central axis 24 of the piston 10 is
equal to or greater than zero and is less than 0.1 D1, and is
preferably zero. Preferably then, the axes 18 and 24 are
coincident.
[0018] The other relationship of parameters also controls the
combustion chamber geometry, and the combustion performance and
emissions in diesel engines, as are listed below:
[0019] 1. The ratio of D2/D1 is greater than 0.43 and is less than
0.83, and is preferably 0.637, D2 being the maximum diameter of the
combustion chamber.
[0020] 2. The ratio of D3/D1 is greater than 0.33 and is less than
0.83 and is preferably 0.548, D3 being the minimum diameter of the
combustion chamber.
[0021] 3. The ratio of RS1/D1 is greater than 0.05 and is less than
0.35, and is preferably 0.18.
[0022] 4. The ratio of RS2/D1 is greater than 0.23 and is less than
0.53, and is preferably 0.334.
[0023] 5. The ratio of RS3/D1 is greater than 1.18 and is less than
4.18, and is preferably 2.18.
[0024] 6. The ratio of RS4/D1 is greater than 0.18 and is less than
0.38, and is preferably 0.28.
[0025] 7. The ratio of H1/D1 is greater than 0.1 and is less than
0.4 and is preferably 0.2, H1 being the depth of the combustion
chamber.
[0026] 8. The ratio of H2/D1 is greater than 0.04 and is less than
0.24, and is preferably 0.144, H2 being the height of the post.
[0027] 9. The radius of the annular surface R1 is equal to the
radius of the annular surface R2. The ratio of R1/D1 and R2/D1 are
each greater than 0.03 and less than 0.25, and is preferably
0.051.
[0028] 10. The radii of the annular surfaces R3 and R4 are very
small. Therefore, ratio of R3/D1 and R4/D1 are each greater than
zero and less than 0.1.
[0029] The curves and smooth transitions of the combustion chamber
12 as previously described promote smooth flow in the combustion
chamber 12 and act to reduce the thermal loading in the combustion
chamber 12. Further, the combustion chamber 12 is preferably
symmetrical about the piston axis 24, but may be offset the
distance H4 as noted in FIG. 1. Accordingly, it is much easier to
turn (form) the combustion chamber 12 as compared to an
asymmetrical combustion chamber defined in a piston.
[0030] It should be noted in FIGS. 2 and 3 that the simulations for
prior art engine and the experimental results for the prior art
engine are in substantial agreement (the empirical and simulation
traces B0 and B0 are substantially coincident) as an indication of
the validity of the simulation. Combustion performance improvement
and pollutant emission reduction are depicted in FIGS. 2 and 3.
FIG. 2 depicts the NOx generation of a known combustion chamber as
depicted by line B0 and the simulated results of NOx generation of
the combustion chamber 12 of the present invention as depicted in
line B27. It is noted that the NOx generation by the combustion
chamber 12 of the present invention is significantly less than the
NOx of the known combustion chamber as depicted by line B0.
[0031] FIG. 3 depicts the simulated soot generation of a known
combustion chamber as depicted by line B0 in comparison with the
simulated soot generation of the combustion chamber 12 of the
present invention as depicted by line B27. It should be noted that
soot generation of the combustion chamber 12 (line B27) is
significantly less than the soot generation of the known combustion
chamber (line B0).
[0032] It will be obvious to those skilled in the art that other
embodiments in addition to the ones described herein are indicated
to be within the scope and breadth of the present application.
Accordingly, the applicant intends to be limited only by the claims
appended hereto.
* * * * *