U.S. patent application number 15/784095 was filed with the patent office on 2018-02-08 for two-stage precombustion chamber for large bore gas engines.
The applicant listed for this patent is Prometheus Applied Technologies, LLC. Invention is credited to David Thomas Lepley, Maria-Emmanuella Sotiropoulou, Luigi P. Tozzi.
Application Number | 20180038270 15/784095 |
Document ID | / |
Family ID | 50185681 |
Filed Date | 2018-02-08 |
United States Patent
Application |
20180038270 |
Kind Code |
A1 |
Tozzi; Luigi P. ; et
al. |
February 8, 2018 |
TWO-STAGE PRECOMBUSTION CHAMBER FOR LARGE BORE GAS ENGINES
Abstract
In certain embodiments, a two-stage precombustion chamber may be
used to reduce engine NOx levels, with fueled precombustion
chambers, while maintaining comparable engine power output and
thermal efficiency. One or more fuel admission points may be
located in either the first prechamber stage or the second
prechamber stage. A more efficient overall combustion characterized
by low levels of NOx formation may be achieved by a two-stage
precombustion chamber system while generating very high energy
flame jets emerging from the second prechamber stage into the main
combustion chamber. A first prechamber stage may be substantially
smaller than a second prechamber stage. The volumes and aspect
ratios of the two prechamber stages, along with the location of the
electrodes within the first stage prechamber, the hole patterns,
angles and the separate fueling, may be selected to create a
distribution of fuel concentration that is substantially higher in
the first stage prechamber compared to the second prechamber
stage.
Inventors: |
Tozzi; Luigi P.; (Fort
Collins, CO) ; Sotiropoulou; Maria-Emmanuella; (Fort
Collins, CO) ; Lepley; David Thomas; (Girard,
OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Prometheus Applied Technologies, LLC |
Fort Collins |
CO |
US |
|
|
Family ID: |
50185681 |
Appl. No.: |
15/784095 |
Filed: |
October 14, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14020770 |
Sep 6, 2013 |
|
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15784095 |
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61697628 |
Sep 6, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02B 23/0675 20130101;
F02B 23/04 20130101; F02B 17/005 20130101; F02B 19/108 20130101;
F02B 19/1014 20130101; H01T 13/54 20130101; F02B 19/1095 20130101;
Y02T 10/125 20130101; Y02T 10/12 20130101; F02B 1/04 20130101; F02B
19/16 20130101; F02B 19/12 20130101; F02B 23/0672 20130101; F02B
19/1009 20130101 |
International
Class: |
F02B 19/12 20060101
F02B019/12; F02B 19/16 20060101 F02B019/16; H01T 13/54 20060101
H01T013/54; F02B 19/10 20060101 F02B019/10 |
Claims
1. A two-stage precombustion chamber comprising: a first prechamber
stage enclosing a first prechamber volume, the first prechamber
stage comprising: one or more first stage holes communicating
between the first prechamber volume and a second prechamber volume;
a primary electrode disposed within the first prechamber volume;
and one or more ground electrodes disposed within the first
prechamber volume and offset from the primary electrode to form one
or more electrode gaps; and a second prechamber stage enclosing the
second prechamber volume, the second prechamber stage comprising:
one or more second stage holes communicating between the second
prechamber volume and a combustion chamber volume; wherein the
two-stage precombustion chamber further comprises at least one fuel
admission point configured to admit fuel to the second prechamber
volume; and wherein the first prechamber volume is smaller than the
second prechamber volume and the first prechamber stage and the
second prechamber stage are arranged in a selected relationship
with respect to each other, such as to generate a first fuel
concentration in the first prechamber volume that is higher than a
second fuel concentration in the second prechamber volume.
2. The two-stage precombustion chamber of claim 1, wherein each of
the one or more first stage holes comprise a penetration angle and
a rotational offset and each of the one or more second stage holes
comprise a hole angle that maintains proportionality of flow
direction and flow momentum in each of the two stages.
3. The two-stage precombustion chamber of claim 1, wherein the one
or more first stage holes and the one or more second stage holes
are arranged to maintain proportionality of flow direction and flow
momentum in each of the two stages.
4. The two-stage precombustion chamber of claim 1, wherein the
first prechamber stage has a first shape and the second prechamber
stage has a second shape and the first and second shapes are
arranged to maintain proportionality of flow direction and flow
momentum in each of the two stages.
5. The two-stage precombustion chamber of claim 1, wherein the
first prechamber stage is positioned relative to the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages.
6. The two-stage precombustion chamber of claim 1, wherein the
first prechamber stage is positioned symmetrically on a center hole
axis of the second prechamber stage to maintain proportionality of
flow direction and flow momentum in each of the two stages.
7. The two-stage precombustion chamber of claim 1, wherein the
first fuel concentration is at least about 5% higher than the
second fuel concentration.
8. The two-stage precombustion chamber of claim 1, wherein the
first prechamber volume is smaller than the second prechamber
volume.
9. The two-stage precombustion chamber of claim 1, wherein the
first prechamber volume is less than about 50% of the second
prechamber volume.
10. The two-stage precombustion chamber of claim 1, wherein each of
the one or more first stage holes defines a first stage hole axis
and each of the one or more second stage holes defines a second
stage hole axis and wherein each first stage hole axis and each
second stage hole axis defines an index angle, a penetration angle
and a rotational offset.
11. The two-stage precombustion chamber of claim 10, wherein the
index angle, the penetration angle and the rotational offset of the
first stage holes and the second stage holes are selected to
generate a first fuel concentration in the first prechamber volume
that is higher than a second fuel concentration in the second
prechamber volume.
12. The two-stage precombustion chamber of claim 1, wherein the
first stage prechamber comprises a passive prechamber spark plug
with a heat range selected to maintain all surface temperatures of
the passive prechamber spark plug below a thermal runaway point
dictated by the air-fuel mixture composition and by the level of
combustion mean effective pressure at which the engine
operates.
13. A two-stage precombustion chamber comprising: a first
prechamber stage enclosing a first prechamber volume, the first
prechamber stage comprising: one or more first stage holes
communicating between the first prechamber volume and a second
prechamber volume; a primary electrode disposed within the first
prechamber volume; and one or more ground electrodes disposed
within the first prechamber volume and offset from the primary
electrode to form one or more electrode gaps; and a second
prechamber stage comprising: an external surface and an internal
surface enclosing the second prechamber volume; one or more second
stage holes communicating between the internal surface and the
external surface; and a fuel admission point configured to admit
fuel into the second prechamber volume wherein the first prechamber
stage and the second prechamber stage are flow-dynamically
matched.
14. The two-stage precombustion chamber of claim 13, wherein each
of the one or more first stage holes comprise a penetration angle
and a rotational offset and each of the one or more second stage
holes comprise a hole angle that maintains proportionality of flow
direction and flow momentum in each of the two stages.
15. The two-stage precombustion chamber of claim 13, wherein the
one or more first stage holes and the one or more second stage
holes are arranged to maintain proportionality of flow direction
and flow momentum in each of the two stages.
16. The two-stage precombustion chamber of claim 13, wherein the
first prechamber stage has a first shape and the second prechamber
stage has a second shape and the first and second shapes are
arranged to maintain proportionality of flow direction and flow
momentum in each of the two stages.
17. The two-stage precombustion chamber of claim 13, wherein the
first prechamber stage is positioned relative to the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages.
18. The two-stage precombustion chamber of claim 13, wherein the
first prechamber stage is positioned symmetrically on a center hole
axis of the second prechamber stage to maintain proportionality of
flow direction and flow momentum in each of the two stages.
19. The two-stage precombustion chamber of claim 13, wherein a
first fuel concentration in the first prechamber volume is higher
than a second fuel concentration in the second prechamber
volume.
20. The two-stage precombustion chamber of claim 19, wherein the
first fuel concentration is higher than the second fuel
concentration before a spark is introduced.
21. The two-stage precombustion chamber of claim 19, wherein the
first fuel concentration is at least about 5% higher than the
second fuel concentration.
22. The two-stage precombustion chamber of claim 13, wherein the
first prechamber volume is smaller than the second prechamber
volume.
23. The two-stage precombustion chamber of claim 13, wherein the
first prechamber volume is less than about 50% of the second
prechamber volume.
24. The two-stage precombustion chamber of claim 13, wherein each
of the one or more first stage holes defines a first stage hole
axis and each of the one or more second stage holes defines a
second stage hole axis and wherein each first stage hole axis and
each second stage hole axis defines an index angle, a penetration
angle and a rotational offset.
25. The two-stage precombustion chamber of claim 24, wherein the
index angle, the penetration angle and the rotational offset of the
first stage holes and the second stage holes are selected to
generate a first fuel concentration in the first prechamber volume
that is higher than a second fuel concentration in the second
prechamber volume.
26. A method of reducing NOx levels in gas engines, comprising:
providing a two-stage precombustion chamber comprising: a first
prechamber stage enclosing a first prechamber volume, the first
prechamber stage comprising: one or more first stage holes
communicating between the first prechamber volume and a second
prechamber volume; a primary electrode disposed within the first
prechamber volume; one or more ground electrodes disposed within
the first prechamber volume and offset from the primary electrode
to form one or more electrode gaps; and a second prechamber stage
enclosing the second prechamber volume, the second prechamber stage
comprising: one or more second stage holes communicating between
the second prechamber volume and a combustion chamber volume;
wherein the first prechamber stage and the second prechamber stage
are flow-dynamically matched; introducing one or more fuel
admission points to the second prechamber volume; and generating a
spark across at least one of the one or more electrode gaps to
ignite a fuel-air mixture in the first prechamber volume.
27. The method of claim 26, wherein each of the one or more first
stage holes comprise a penetration angle and a rotational offset
and each of the one or more second stage holes comprise a hole
angle that maintain proportionality of flow direction and flow
momentum in each of the two stages.
28. The method of claim 26, wherein the one or more first stage
holes and the one or more second stage holes are arranged to
maintain proportionality of flow direction and flow momentum in
each of the two stages.
29. The method of claim 26, wherein the first prechamber stage has
a first shape and the second prechamber stage has a second shape
and the first and second shapes are arranged to maintain
proportionality of flow direction and flow momentum in each of the
two stages.
30. The method of claim 26, wherein the first prechamber stage is
positioned relative to the second prechamber stage to maintain
proportionality of flow direction and flow momentum in each of the
two stages.
31. The method of claim 26, wherein the first prechamber stage is
positioned symmetrically on a center hole axis of the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages.
32. The method of claim 26, wherein the first prechamber volume is
smaller than the second prechamber volume.
33. The method of claim 26, wherein the first prechamber volume is
less than about 50% of the second prechamber volume.
34. The method of claim 26, wherein the first prechamber volume
contains a first fuel-air mixture with a first fuel concentration
and the second prechamber volume contains a second fuel-air mixture
with a second fuel concentration and wherein the first fuel
concentration is higher than the second fuel concentration.
35. The method of claim 34, wherein the first fuel concentration is
higher than the second fuel concentration before the spark is
generated.
36. The method of claim 34, wherein the first fuel concentration is
at least about 5% higher than the second fuel concentration.
37. The method of claim 26, wherein each of the one or more first
stage holes defines a first stage hole axis and each of the one or
more second stage holes defines a second stage hole axis and
wherein each first stage hole axis and each second stage hole axis
defines an index angle, a penetration angle and a rotational
offset.
38. The method of claim 37, wherein the index angle, the
penetration angle and the rotational offset of the first stage
holes and the second stage holes are selected to generate a first
fuel-air mixture in the first prechamber volume with a higher fuel
concentration than a second fuel-air mixture in the second
prechamber volume.
39. The method of claim 26, further comprising: providing cooling
to the first stage prechamber to maintain all surface temperatures
of the first prechamber below a thermal runaway point dictated by
the air-fuel mixture composition and by the level of combustion
mean effective pressure at which the engine operates.
40. The method of claim 26, further comprising: providing cooling
to the second stage prechamber to maintain all surface temperatures
of the second prechamber to prevent flame quenching and to promote
flame propagation speed as dictated by the air-fuel mixture
composition and flow dynamic.
41. A method of reducing NOx levels in gas engines, comprising:
providing a two-stage precombustion chamber comprising: a first
prechamber stage enclosing a first prechamber volume, the first
prechamber stage comprising: one or more first stage holes
communicating between the first prechamber volume and a second
prechamber volume; a primary electrode disposed within the first
prechamber volume; one or more ground electrodes disposed within
the first prechamber volume and offset from the primary electrode
to form one or more electrode gaps; and a second prechamber stage
comprising: an external surface and an internal surface enclosing
the second prechamber volume; and one or more second stage holes
communicating between the internal surface and the external
surface; wherein the first prechamber stage and the second
prechamber stage are flow-dynamically matched; introducing one or
more fuel in-filling streams to the second prechamber volume; and
generating a spark across at least one of the one or more
electrodes gaps to ignite a fuel-air mixture in the first
prechamber volume.
42. The method of claim 41, wherein each of the one or more first
stage holes comprise a penetration angle and a rotational offset
and each of the one or more second stage holes comprise a hole
angle that maintains proportionality of flow direction and flow
momentum in each of the two stages.
43. The method of claim 41, wherein the one or more first stage
holes and the one or more second stage holes are arranged to
maintain proportionality of flow direction and flow momentum in
each of the two stages.
44. The method of claim 41, wherein the first prechamber stage has
a first shape and the second prechamber stage has a second shape
and the first and second shapes are arranged to maintain
proportionality of flow direction and flow momentum in each of the
two stages.
45. The method of claim 41, wherein the first prechamber stage is
positioned relative to the second prechamber stage to maintain
proportionality of flow direction and flow momentum in each of the
two stages.
46. The method of claim 41, wherein the first prechamber stage is
positioned symmetrically on a center hole axis of the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages.
47. The method of claim 41, wherein the first prechamber volume is
smaller than the second prechamber volume.
48. The method of claim 41, wherein the first prechamber volume is
less than about 50% of the second prechamber volume.
49. The method of claim 41, wherein the first prechamber volume
contains a first fuel-air mixture with a first fuel concentration
and the second prechamber volume contains a second fuel-air mixture
with a second fuel concentration and wherein the first fuel
concentration is higher than the second fuel concentration.
50. The method of claim 49, wherein the first fuel concentration is
higher than the second fuel concentration before the spark is
generated.
51. The method of claim 49, wherein the first fuel concentration is
at least about 5% higher than the second fuel concentration.
52. The method of claim 41, wherein each of the one or more first
stage holes defines a first stage hole axis and each of the one or
more second stage holes defines a second stage hole axis and
wherein each first stage hole axis and each second stage hole axis
defines an index angle, a penetration angle and a rotational
offset.
53. The method of claim 52, wherein the index angle, the
penetration angle and the rotational offset of the first stage
holes and the second stage holes are selected to generate a first
fuel-air mixture in the first prechamber volume with a higher fuel
concentration than a second fuel-air mixture in the second
prechamber volume.
54. A method for controlling the admission of fuel to a two-stage
precombustion chamber utilizing an electrically actuated valve,
comprising adjusting a quantity of fuel admitted and timing of
admitting the quantity of fuel relative to engine position to
achieve a desired fuel distribution in the two-stage precombustion
chamber; wherein the two stages are flow-dynamically matched.
55. The method of claim 54, wherein at least one of the quantity of
fuel and the timing of admitting the fuel is adjusted utilizing a
closed feedback loop based on one or more previous operating cycles
and wherein the feedback loop includes feedback generated from the
two-stage precombustion chamber or the main combustion chamber.
56. A method for controlling and adjusting the characteristics of a
spark discharge event within a two-stage precombustion chamber,
comprising utilizing an electronically controlled ignition system
to adjust the characteristics of a spark discharge event based on
the fuel distribution present in a two-stage precombustion chamber;
wherein the two stages are flow-dynamically matched.
57. The method of claim 56, wherein the characteristics of the
spark discharge are adjusted utilizing a closed feedback loop based
on one or more previous operating cycles and wherein the feedback
loop includes feedback generated from the two-stage precombustion
chamber or the main combustion chamber.
Description
I. CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/020,770, entitled "Two-Stage Precombustion
Chamber For Large Bore Gas Engines," and filed Sep. 6, 2013, which
claims priority of U.S. Patent Application No. 61/697,628, entitled
"Two-Stage Precombustion Chamber For Large Bore Gas Engines," and
filed Sep. 6, 2012; which is related to U.S. patent application
Ser. No. 13/602,148, entitled "Method and apparatus for achieving
high power flame jets while reducing quenching and autoignition in
prechamber spark plugs for gas engines," and filed on Sep. 1, 2012
and International Patent Application Number PCT/US2012/53568,
entitled "Method and apparatus for achieving high power flame jets
while reducing quenching and autoignition in prechamber spark plugs
for gas engines," and filed on Sep. 1, 2012, both of which claim
priority to U.S. Patent Application No. 61/573,290, entitled
"Method and apparatus for achieving high power flame jets while
reducing quenching and autoignition in prechamber spark plugs for
gas engines," and filed on Sep. 3, 2011. This application is also
related to International Patent Application Number
PCT/US2011/002012, entitled "Prechamber Ignition System," and filed
on Dec. 30, 2011, which claims priority to U.S. Patent Application
No. 61/460,337, entitled "High efficiency ricochet effect passive
chamber spark plug," and filed on Dec. 31, 2010. The entirety of
each of the foregoing patent applications is incorporated by
reference herein in their entirety.
II. FIELD OF THE INVENTION
[0002] The disclosure generally relates to systems and methods for
a two-stage precombustion chamber, and more particularly to a
two-stage precombustion chamber that reduces NOx emissions in
fueled, precombustion chamber gas engines. The two-stage
precombustion chamber can be also achieved by simply replacing a
conventional spark plug, used with conventional fueled prechamber,
with a passive prechamber spark plug.
III. BACKGROUND OF THE INVENTION
[0003] Large gas engines with cylinder bore diameter greater than
200 mm typically use fuel-fed, rich precombustion chambers to
enhance flame propagation rate with lean air/fuel mixtures in the
main combustion chamber. A drawback of this type of system is that
a fuel rich prechamber generates very high NOx and even though the
main chamber generates very low NOx the combined amount remains
higher than the legislated amount.
[0004] There is a need to address the foregoing deficiencies in the
art.
IV. SUMMARY OF THE INVENTION
[0005] In certain embodiments, a two-stage precombustion chamber is
disclosed comprising: a first prechamber stage enclosing a first
prechamber volume, the first prechamber stage comprising: one or
more first stage holes communicating between the first prechamber
volume and a second prechamber volume; a primary electrode disposed
within the first prechamber volume; and one or more ground
electrodes disposed within the first prechamber volume and offset
from the primary electrode to form one or more electrode gaps; and
a second prechamber stage enclosing the second prechamber volume,
the second prechamber stage comprising: one or more second stage
holes communicating between the second prechamber volume and a
combustion chamber volume; wherein the two-stage precombustion
chamber further comprises at least one fuel admission point
configured to admit fuel to the second prechamber volume; and
wherein the first prechamber volume is smaller than the second
prechamber volume and the first prechamber stage and the second
prechamber stage are arranged in a selected relationship with
respect to each other, such as to generate a first fuel
concentration in the first prechamber volume that is higher than a
second fuel concentration in the second prechamber volume. Each of
the one or more first stage holes may comprise a penetration angle
and a rotational offset and each of the one or more second stage
holes comprise a hole angle that maintains proportionality of flow
direction and flow momentum in each of the two stages. The one or
more first stage holes and the one or more second stage holes may
be arranged to maintain proportionality of flow direction and flow
momentum in each of the two stages. The first prechamber stage may
have a first shape and the second prechamber stage may have a
second shape and the first and second shapes may be arranged to
maintain proportionality of flow direction and flow momentum in
each of the two stages. The first prechamber stage may be
positioned relative to the second prechamber stage to maintain
proportionality of flow direction and flow momentum in each of the
two stages. The first prechamber stage may be positioned
symmetrically on a center hole axis of the second prechamber stage
to maintain proportionality of flow direction and flow momentum in
each of the two stages. The first fuel concentration may be at
least about 5% higher than the second fuel concentration. The first
prechamber volume may be smaller than the second prechamber volume.
The first prechamber volume may be less than about 50% of the
second prechamber volume. Each of the one or more first stage holes
may define a first stage hole axis and each of the one or more
second stage holes may define a second stage hole axis and each
first stage hole axis and each second stage hole axis may define an
index angle, a penetration angle and a rotational offset. The index
angle, the penetration angle and the rotational offset of the first
stage holes and the second stage holes may be selected to generate
a first fuel concentration in the first prechamber volume that is
higher than a second fuel concentration in the second prechamber
volume. The first stage prechamber may comprise a passive
prechamber spark plug with a heat range selected to maintain all
surface temperatures of the passive prechamber spark plug below a
thermal runaway point dictated by the air-fuel mixture composition
and by the level of combustion mean effective pressure at which the
engine operates.
[0006] In certain embodiments, a two-stage precombustion chamber is
disclosed comprising: a first prechamber stage enclosing a first
prechamber volume, the first prechamber stage comprising: one or
more first stage holes communicating between the first prechamber
volume and a second prechamber volume; a primary electrode disposed
within the first prechamber volume; and one or more ground
electrodes disposed within the first prechamber volume and offset
from the primary electrode to form one or more electrode gaps; and
a second prechamber stage comprising: an external surface and an
internal surface enclosing the second prechamber volume; one or
more second stage holes communicating between the internal surface
and the external surface; and a fuel admission point configured to
admit fuel into the second prechamber volume wherein the first
prechamber stage and the second prechamber stage are
flow-dynamically matched. Each of the one or more first stage holes
may comprise a penetration angle and a rotational offset and each
of the one or more second stage holes may comprise a hole angle
that maintains proportionality of flow direction and flow momentum
in each of the two stages. The one or more first stage holes and
the one or more second stage holes may be arranged to maintain
proportionality of flow direction and flow momentum in each of the
two stages. The first prechamber stage may have a first shape and
the second prechamber stage may have a second shape and the first
and second shapes may be arranged to maintain proportionality of
flow direction and flow momentum in each of the two stages. The
first prechamber stage may be positioned relative to the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages. The first prechamber stage
may be positioned symmetrically on a center hole axis of the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages. A first fuel concentration
in the first prechamber volume may be higher than a second fuel
concentration in the second prechamber volume. The first fuel
concentration may be higher than the second fuel concentration
before a spark is introduced. The first fuel concentration may be
at least about 5% higher than the second fuel concentration. The
first prechamber volume may be smaller than the second prechamber
volume. The first prechamber volume may be less than about 50% of
the second prechamber volume. Each of the one or more first stage
holes may define a first stage hole axis and each of the one or
more second stage holes may define a second stage hole axis and
wherein each first stage hole axis and each second stage hole axis
may define an index angle, a penetration angle and a rotational
offset. The index angle, the penetration angle and the rotational
offset of the first stage holes and the second stage holes may be
selected to generate a first fuel concentration in the first
prechamber volume that is higher than a second fuel concentration
in the second prechamber volume.
[0007] In certain embodiments, a method of reducing NOx levels in
gas engines is disclosed, comprising: providing a two-stage
precombustion chamber comprising: a first prechamber stage
enclosing a first prechamber volume, the first prechamber stage
comprising: one or more first stage holes communicating between the
first prechamber volume and a second prechamber volume; a primary
electrode disposed within the first prechamber volume; one or more
ground electrodes disposed within the first prechamber volume and
offset from the primary electrode to form one or more electrode
gaps; and a second prechamber stage enclosing the second prechamber
volume, the second prechamber stage comprising: one or more second
stage holes communicating between the second prechamber volume and
a combustion chamber volume; wherein the first prechamber stage and
the second prechamber stage are flow-dynamically matched;
introducing one or more fuel admission points to the second
prechamber volume; and generating a spark across at least one of
the one or more electrode gaps to ignite a fuel-air mixture in the
first prechamber volume. Each of the one or more first stage holes
may comprise a penetration angle and a rotational offset and each
of the one or more second stage holes may comprise a hole angle
that maintain proportionality of flow direction and flow momentum
in each of the two stages. The one or more first stage holes and
the one or more second stage holes may be arranged to maintain
proportionality of flow direction and flow momentum in each of the
two stages. The first prechamber stage may have a first shape and
the second prechamber stage may have a second shape and the first
and second shapes may be arranged to maintain proportionality of
flow direction and flow momentum in each of the two stages. The
first prechamber stage may be positioned relative to the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages. The first prechamber stage
may be positioned symmetrically on a center hole axis of the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages. The first prechamber
volume may be smaller than the second prechamber volume. The first
prechamber volume may be less than about 50% of the second
prechamber volume. The first prechamber volume may contain a first
fuel-air mixture with a first fuel concentration and the second
prechamber volume may contain a second fuel-air mixture with a
second fuel concentration and the first fuel concentration may be
higher than the second fuel concentration. The first fuel
concentration may be higher than the second fuel concentration
before the spark is generated. The first fuel concentration may be
at least about 5% higher than the second fuel concentration. Each
of the one or more first stage holes may define a first stage hole
axis and each of the one or more second stage holes may define a
second stage hole axis and each first stage hole axis and each
second stage hole axis may define an index angle, a penetration
angle and a rotational offset. The index angle, the penetration
angle and the rotational offset of the first stage holes and the
second stage holes may be selected to generate a first fuel-air
mixture in the first prechamber volume with a higher fuel
concentration than a second fuel-air mixture in the second
prechamber volume. The method may further comprise providing
cooling to the first stage prechamber to maintain all surface
temperatures of the first prechamber below a thermal runaway point
dictated by the air-fuel mixture composition and by the level of
combustion mean effective pressure at which the engine operates.
The method may further comprise providing cooling to the second
stage prechamber to maintain all surface temperatures of the second
prechamber to prevent flame quenching and to promote flame
propagation speed as dictated by the air-fuel mixture composition
and flow dynamic.
[0008] In certain embodiments, a method of reducing NOx levels in
gas engines is disclosed, comprising: providing a two-stage
precombustion chamber comprising: a first prechamber stage
enclosing a first prechamber volume, the first prechamber stage
comprising: one or more first stage holes communicating between the
first prechamber volume and a second prechamber volume; a primary
electrode disposed within the first prechamber volume; one or more
ground electrodes disposed within the first prechamber volume and
offset from the primary electrode to form one or more electrode
gaps; and a second prechamber stage comprising: an external surface
and an internal surface enclosing the second prechamber volume; and
one or more second stage holes communicating between the internal
surface and the external surface; wherein the first prechamber
stage and the second prechamber stage are flow-dynamically matched;
introducing one or more fuel in-filling streams to the second
prechamber volume; and generating a spark across at least one of
the one or more electrodes gaps to ignite a fuel-air mixture in the
first prechamber volume. Each of the one or more first stage holes
may comprise a penetration angle and a rotational offset and each
of the one or more second stage holes may comprise a hole angle
that maintains proportionality of flow direction and flow momentum
in each of the two stages. The one or more first stage holes and
the one or more second stage holes may be arranged to maintain
proportionality of flow direction and flow momentum in each of the
two stages. The first prechamber stage may have a first shape and
the second prechamber stage may have a second shape and the first
and second shapes may be arranged to maintain proportionality of
flow direction and flow momentum in each of the two stages. The
first prechamber stage may be positioned relative to the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages. The first prechamber stage
may be positioned symmetrically on a center hole axis of the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages. The first prechamber
volume may be smaller than the second prechamber volume. The first
prechamber volume may be less than about 50% of the second
prechamber volume. The first prechamber volume may contain a first
fuel-air mixture with a first fuel concentration and the second
prechamber volume may contain a second fuel-air mixture with a
second fuel concentration and the first fuel concentration may be
higher than the second fuel concentration. The first fuel
concentration may be higher than the second fuel concentration
before the spark is generated. The first fuel concentration may be
at least about 5% higher than the second fuel concentration. Each
of the one or more first stage holes may define a first stage hole
axis and each of the one or more second stage holes may define a
second stage hole axis and each first stage hole axis and each
second stage hole axis may define an index angle, a penetration
angle and a rotational offset. The index angle, the penetration
angle and the rotational offset of the first stage holes and the
second stage holes may be selected to generate a first fuel-air
mixture in the first prechamber volume with a higher fuel
concentration than a second fuel-air mixture in the second
prechamber volume.
[0009] In certain embodiments, a method for controlling the
admission of fuel to a two-stage precombustion chamber utilizing an
electrically actuated valve is disclosed, comprising adjusting a
quantity of fuel admitted and timing of admitting the quantity of
fuel relative to engine position to achieve a desired fuel
distribution in the two-stage precombustion chamber; wherein the
two stages are flow-dynamically matched. At least one of the
quantity of fuel and the timing of admitting the fuel may be
adjusted utilizing a closed feedback loop based on one or more
previous operating cycles and the feedback loop may include
feedback generated from the two-stage precombustion chamber or the
main combustion chamber.
[0010] In certain embodiments, a method for controlling and
adjusting the characteristics of a spark discharge event within a
two-stage precombustion chamber is disclosed, comprising utilizing
an electronically controlled ignition stem to adjust the
characteristics of a spark discharge event based on the fuel
distribution present in a two-stage precombustion chamber; wherein
the two stages are flow-dynamically matched. The characteristics of
the spark discharge may be adjusted utilizing a closed feedback
loop based on one or more previous operating cycles and the
feedback loop may include feedback generated from the two-stage
precombustion chamber or the main combustion chamber.
[0011] In certain embodiments, a two-stage precombustion chamber is
disclosed comprising: a first prechamber stage enclosing a first
prechamber volume, the first prechamber stage comprising: one or
more first stage holes communicating between the first prechamber
volume and a second prechamber volume; a primary electrode disposed
within the first prechamber volume; and one or more ground
electrodes disposed within the first prechamber volume and offset
from the primary electrode to form one or more electrode gaps; and
a second prechamber stage enclosing the second prechamber volume,
the second prechamber stage comprising: one or more second stage
holes communicating between the second prechamber volume and a
combustion chamber volume; wherein the first prechamber stage and
the second prechamber stage are flow-dynamically matched. Each of
the one or more first stage holes may comprise a penetration angle
and a rotational offset and each of the one or more second stage
holes comprise a hole angle that maintain proportionality of flow
direction and flow momentum in each of the two stages. The one or
more first stage holes and the one or more second stage holes may
be arranged to maintain proportionality of flow direction and flow
momentum in each of the two stages. The first prechamber stage has
a first shape and the second prechamber stage may have a second
shape and the first and second shapes may be arranged to maintain
proportionality of flow direction and flow momentum in each of the
two stages. The first shape may be a first bullet shape and the
second shape may be a second bullet shape. The first prechamber
stage may be positioned relative to the second prechamber stage to
maintain proportionality of flow direction and flow momentum in
each of the two stages. The first prechamber stage may be
positioned symmetrically on a center hole axis of the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages. A first fuel concentration
in the first prechamber volume may be higher than a second fuel
concentration in the second prechamber volume. The first fuel
concentration may be higher than the second fuel concentration
before a spark is introduced. The first fuel concentration may be
at least about 5% higher than the second fuel concentration. The
first prechamber volume may be smaller than the second prechamber
volume. The first prechamber volume may be less than about 50% of
the second prechamber volume. The two-stage precombustion chamber
may further comprise a fuel admission point configured to admit
fuel into the first prechamber volume. The two-stage precombustion
chamber may further comprise a fuel admission point configured to
admit fuel into the second prechamber volume. Each of the one or
more first stage holes may define a first stage hole axis and each
of the one or more second stage holes may define a second stage
hole axis and each first stage hole axis and each second stage hole
axis may define an index angle, a penetration angle and a
rotational offset. The index angle, the penetration angle and the
rotational offset of the first stage holes and the second stage
holes may be selected to generate a first fuel concentration in the
first prechamber volume that is higher than a second fuel
concentration in the second prechamber volume. The first stage
prechamber may comprise a passive prechamber spark plug with a heat
range selected to maintain all surface temperatures of the passive
prechamber spark plug below a thermal runaway point dictated by the
air-fuel mixture composition and by the level of combustion mean
effective pressure at which the engine operates.
[0012] In certain embodiments, a two-stage precombustion chamber is
disclosed comprising: a first prechamber stage enclosing a first
prechamber volume, the first prechamber stage comprising: one or
more first stage holes communicating between the first prechamber
volume and a second prechamber volume; a primary electrode disposed
within the first prechamber volume; and one or more ground
electrodes disposed within the first prechamber volume and offset
from the primary electrode to form one or more electrode gaps; and
a second prechamber stage comprising: an external surface and an
internal surface enclosing the second prechamber volume; and one or
more second stage holes communicating between the internal surface
and the external surface; wherein the first prechamber stage and
the second prechamber stage are flow-dynamically matched. Each of
the one or more first stage holes may comprise a penetration angle
and a rotational offset and each of the one or more second stage
holes may comprise a hole angle that maintain proportionality of
flow direction and flow momentum in each of the two stages. The one
or more first stage holes and the one or more second stage holes
may be arranged to maintain proportionality of flow direction and
flow momentum in each of the two stages. The first prechamber stage
may have a first shape and the second prechamber stage may have a
second shape and the first and second shapes may be arranged to
maintain proportionality of flow direction and flow momentum in
each of the two stages. The first shape may be a first bullet shape
and the second shape may be a second bullet shape. The first
prechamber stage may be positioned relative to the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages. The first prechamber stage
may be positioned symmetrically on a center hole axis of the second
prechamber stage to maintain proportionality of flow direction and
flow momentum in each of the two stages. A first fuel concentration
in the first prechamber volume may be higher than a second fuel
concentration in the second prechamber volume. The first fuel
concentration may be higher than the second fuel concentration
before a spark is introduced. The first fuel concentration may be
at least about 5% higher than the second fuel concentration. The
first prechamber volume may be smaller than the second prechamber
volume. The first prechamber volume may be less than about 50% of
the second prechamber volume. The two-stage precombustion chamber
may further comprise a fuel admission point configured to admit
fuel into the first prechamber volume. The two-stage precombustion
chamber may further comprise a fuel admission point configured to
admit fuel into the second prechamber volume. Each of the one or
more first stage holes may define a first stage hole axis and each
of the one or more second stage holes may define a second stage
hole axis and each first stage hole axis and each second stage hole
axis may define an index angle, a penetration angle and a
rotational offset. The index angle, the penetration angle and the
rotational offset of the first stage holes and the second stage
holes may be selected to generate a first fuel concentration in the
first prechamber volume that is higher than a second fuel
concentration in the second prechamber volume.
[0013] In certain embodiments, a method of reducing NOx levels in
gas engines is disclosed, comprising: providing a two-stage
precombustion chamber comprising: a first prechamber stage
enclosing a first prechamber volume, the first prechamber stage
comprising: one or more first stage holes communicating between the
first prechamber volume and a second prechamber volume; a primary
electrode disposed within the first prechamber volume; one or more
ground electrodes disposed within the first prechamber volume and
offset from the primary electrode to form one or more electrode
gaps; and a second prechamber stage enclosing the second prechamber
volume, the second prechamber stage comprising: one or more second
stage holes communicating between the second prechamber volume and
a combustion chamber volume; wherein the first prechamber stage and
the second prechamber stage are flow-dynamically matched;
introducing one or more fuel admission points to a selected one of
the first prechamber volume and the second prechamber volume; and
generating a spark across at least one of the one or more electrode
gaps to ignite a fuel-air mixture in the first prechamber volume.
Each of the one or more first stage holes may comprise a
penetration angle and a rotational offset and each of the one or
more second stage holes may comprise a hole angle that maintain
proportionality of flow direction and flow momentum in each of the
two stages. The one or more first stage holes and the one or more
second stage holes may be arranged to maintain proportionality of
flow direction and flow momentum in each of the two stages. The
first prechamber stage may have a first shape and the second
prechamber stage may have a second shape and the first and second
shapes may be arranged to maintain proportionality of flow
direction and flow momentum in each of the two stages. The first
shape may be a first bullet shape and the second shape may be a
second bullet shape. The first prechamber stage may be positioned
relative to the second prechamber stage to maintain proportionality
of flow direction and flow momentum in each of the two stages. The
first prechamber stage may be positioned symmetrically on a center
hole axis of the second prechamber stage to maintain
proportionality of flow direction and flow momentum in each of the
two stages. The first prechamber volume may be smaller than the
second prechamber volume. The first prechamber volume may be less
than about 50% of the second prechamber volume. The one or more
fuel admission points may be introduced into the first prechamber
volume. The one or more fuel admission points may be introduced
into the second prechamber volume. The first prechamber volume may
contain a first fuel-air mixture with a first fuel concentration
and the second prechamber volume may contain a second fuel-air
mixture with a second fuel concentration and the first fuel
concentration may be higher than the second fuel concentration. The
first fuel concentration may be higher than the second fuel
concentration before the spark is generated. The first fuel
concentration may be at least about 5% higher than the second fuel
concentration. Each of the one or more first stage holes may define
a first stage hole axis and each of the one or more second stage
holes may define a second stage hole axis and each first stage hole
axis and each second stage hole axis may define an index angle, a
penetration angle and a rotational offset. The index angle, the
penetration angle and the rotational offset of the first stage
holes and the second stage holes may be selected to generate a
first fuel-air mixture in the first prechamber volume with a higher
fuel concentration than a second fuel-air mixture in the second
prechamber volume. The method may further comprise: providing
cooling to the first stage prechamber to maintain all surface
temperatures of the first prechamber below a thermal runaway point
dictated by the air-fuel mixture composition and by the level of
combustion mean effective pressure at which the engine operates.
The method may further comprise: providing cooling to the second
stage prechamber to maintain all surface temperatures of the second
prechamber to prevent flame quenching and to promote flame
propagation speed as dictated by the air-fuel mixture composition
and flow dynamic.
[0014] In certain embodiments, a method of reducing NOx levels in
gas engines is disclosed, comprising: providing a two-stage
precombustion chamber comprising: a first prechamber stage
enclosing a first prechamber volume, the first prechamber stage
comprising: one or more first stage holes communicating between the
first prechamber volume and a second prechamber volume; a primary
electrode disposed within the first prechamber volume; one or more
ground electrodes disposed within the first prechamber volume and
offset from the primary electrode to form one or more electrode
gaps; and a second prechamber stage comprising: an external surface
and an internal surface enclosing the second prechamber volume; and
one or more second stage holes communicating between the internal
surface and the external surface; wherein the first prechamber
stage and the second prechamber stage are flow-dynamically matched;
introducing one or more fuel in-filling streams to a selected one
of the first prechamber volume and the second prechamber volume;
and generating a spark across at least one of the one or more
electrode gaps to ignite a fuel-air mixture in the first prechamber
volume. Each of the one or more first stage holes may comprise a
penetration angle and a rotational offset and each of the one or
more second stage holes may comprise a hole angle that maintains
proportionality of flow direction and flow momentum in each of the
two stages. The one or more first stage holes and the one or more
second stage holes may be arranged to maintain proportionality of
flow direction and flow momentum in each of the two stages. The
first prechamber stage may have a first shape and the second
prechamber stage may have a second shape and the first and second
shapes may be arranged to maintain proportionality of flow
direction and flow momentum in each of the two stages. The first
shape may be a first bullet shape and the second shape may be a
second bullet shape. The first prechamber stage may be positioned
relative to the second prechamber stage to maintain proportionality
of flow direction and flow momentum in each of the two stages. The
first prechamber stage may be positioned symmetrically on a center
hole axis of the second prechamber stage to maintain
proportionality of flow direction and flow momentum in each of the
two stages. The first prechamber volume may be smaller than the
second prechamber volume. The first prechamber volume may be less
than about 50% of the second prechamber volume. The one or more
fuel admission points may be introduced into the first prechamber
volume. The one or more fuel admission points may be introduced
into the second prechamber volume. The first prechamber volume may
contain a first fuel-air mixture with a first fuel concentration
and the second prechamber volume may contain a second fuel-air
mixture with a second fuel concentration and the first fuel
concentration may be higher than the second fuel concentration. The
first fuel concentration may be higher than the second fuel
concentration before the spark is generated. The first fuel
concentration may be at least about 5% higher than the second fuel
concentration. Each of the one or more first stage holes may define
a first stage hole axis and each of the one or more second stage
holes may define a second stage hole axis and each first stage hole
axis and each second stage hole axis may define an index angle, a
penetration angle and a rotational offset. The index angle, the
penetration angle and the rotational offset of the first stage
holes and the second stage holes may be selected to generate a
first fuel-air mixture in the first prechamber volume with a higher
fuel concentration than a second fuel-air mixture in the second
prechamber volume.
[0015] In certain embodiments, a method for controlling the
admission of fuel to a two-stage precombustion chamber utilizing an
electrically actuated valve is disclosed, comprising adjusting a
quantity of fuel admitted and timing of admitting the quantity of
fuel relative to engine position to achieve a desired fuel
distribution in the two-stage precombustion chamber; wherein the
two stages are flow-dynamically matched. At least one of the
quantity of fuel and the timing of admitting the fuel may be
adjusted utilizing a closed feedback loop based on one or more
previous operating cycles and wherein the feedback loop includes
feedback generated from the two-stage precombustion chamber or the
main combustion chamber.
[0016] In certain embodiments, a method for controlling and
adjusting the characteristics of a spark discharge event within a
two-stage precombustion chamber is disclosed, comprising utilizing
an electronically controlled ignition system to adjust the
characteristics of a spark discharge event based on the fuel
distribution present in a two-stage precombustion chamber; wherein
the two stages are flow-dynamically matched. The characteristics of
the spark discharge may be adjusted utilizing a closed feedback
loop based on one or more previous operating cycles and wherein the
feedback loop may include feedback generated from the two-stage
precombustion chamber or the main combustion chamber.
V. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 depicts two variations of a two-stage precombustion
chamber in accordance with certain embodiments.
[0018] FIG. 2 depicts an exemplary comparison of NOx output between
a conventional precombustion chamber with a conventional spark plug
and a two-stage precombustion chamber with a passive prechamber
spark plug in accordance with certain embodiments.
[0019] FIG. 3 depicts the total volume of certain embodiments of a
passive prechamber spark plug, which may be used as the first stage
in a two-stage precombustion chamber in accordance with certain
embodiments.
[0020] FIG. 4 depicts the volume ahead of the gap of certain
embodiments of a passive prechamber spark plug, which may be used
as the first stage in a two-stage precombustion chamber in
accordance with certain embodiments.
[0021] FIG. 5 depicts the volume behind the gap of certain
embodiments of a passive prechamber spark plug, which may be used
as the first stage in a two-stage precombustion chamber in
accordance with certain embodiments.
[0022] FIG. 6 depicts an exemplary penetration angle of a passive
prechamber spark plug which may be used as the first stage in a
two-stage precombustion chamber in accordance with certain
embodiments.
[0023] FIG. 7 depicts an exemplary index angle of a passive
prechamber spark plug, which may be used as the first stage in a
two-stage precombustion chamber in accordance with certain
embodiments.
[0024] FIG. 8 depicts an exemplary rotational offset of a passive
prechamber spark plug, which may be used as the first stage in a
two-stage precombustion chamber in accordance with certain
embodiments.
[0025] FIG. 9 depicts an exemplary pattern radius of a passive
prechamber spark plug, which may be used as the first stage in a
two-stage precombustion chamber in accordance with certain
embodiments.
[0026] FIG. 10 depicts an exemplary prechamber ceiling distance
from center electrode of a passive prechamber spark plug, which may
be used as the first stage in a two-stage precombustion chamber in
accordance with certain embodiments.
[0027] FIG. 11 depicts an exemplary port length of a passive
prechamber spark plug, which may be used as the first stage in a
two-stage precombustion chamber in accordance with certain
embodiments.
[0028] FIG. 12 depicts an exemplary port diameter of a passive
prechamber spark plug, which may be used as the first stage in a
two-stage precombustion chamber in accordance with certain
embodiments.
[0029] FIG. 13 depicts an exemplary precombustion chamber insertion
depth of a passive prechamber spark plug, which may be used as the
first stage in a two-stage precombustion chamber in accordance with
certain embodiments.
VI. DETAILED DESCRIPTION
[0030] In certain embodiments, the two-stage precombustion chamber
100 concept disclosed herein, may be used to reduce engine NOx
levels, with fueled precombustion chambers, while maintaining
comparable engine power output and thermal efficiency.
[0031] Certain embodiments provide a method and a structure to
achieve more effective combustion with leaner mixtures resulting in
lower NOx. In certain embodiments as shown in FIG. 1, conventional
precombustion chambers may be modified so that a first stage of
combustion 110 occurs in a relatively small volume, with a
relatively fuel rich mixture 170, and a second stage of combustion
120 occurs in a relatively larger volume with a relatively fuel
lean mixture 150. In certain embodiments, a more efficient overall
combustion characterized by low levels of NOx formation can be
achieved by the two-stage precombustion chamber 100 system while
generating very high energy flame jets 140 emerging from the second
prechamber stage 120 into the main combustion chamber.
[0032] In certain embodiments, the two-stage prechamber 100 system
can be achieved by simply replacing a conventional spark plug, used
in fueled prechamber, with a passive prechamber spark plug to
provide for the first stage prechamber 110 in the two-stage
precombustion chamber 100 system.
[0033] The amount of NOx produced in a prechamber may be mainly
dictated by the air-fuel ratio and by the volume of reactants. As
the volume of reactants at the lower air-fuel ratio is decreased,
the amount of NOx formed may be proportionally reduced. In certain
embodiments, with the 2-stage precombustion, the volume of the fuel
rich 170 stage can be reduced by at least a factor of 2, thereby
reducing NOx production by approximately a factor of 2. In certain
embodiments, the flame jet energy also may be dictated by the
air-fuel ratio and by the volume of reactants. As the volume of
reactants at the lower air-fuel ratio is decreased, the flame jet
energy also may be reduced. In certain embodiments with the
two-stage precombustion 100, the second prechamber stage 120,
characterized by a relatively leaner mixture 150, is ignited by
powerful flame jets 140 emerging from the relatively fuel rich 170
first prechamber 110 stage. The ignition by powerful flame jets 140
may result in a fast combustion of the leaner mixture 150 in the
second prechamber stage 120, which may generate high energy flame
jets 140 from the second prechamber stage 120. These high energy
flame jets 140 may ignite the lean air fuel mixture 150 in the
engine main combustion chamber 120 and achieve low overall NOx
emissions, while maintaining comparable engine power output and
thermal efficiency to a system employing a conventional
precombustion chamber.
[0034] In certain embodiments as shown in FIG. 1, the volume of the
first prechamber stage 110 may be substantially smaller than the
volume of the second prechamber stage 120. The volume of the first
prechamber stage 110 may be less than about 50% of the volume of
the second prechamber stage 120.
[0035] In certain embodiments, either the first prechamber stage
110 or the second prechamber stage 120 can be fueled directly by a
separate fuel line. In certain embodiments, if the first prechamber
stage 110 is fueled directly by a separate fuel admission point 130
as shown in the top two figures of FIG. 1, a richer first fuel
concentration in the first prechamber 110 stage may result than if
the second prechamber 120 stage is fueled directly by a separate
fuel admission point 130 as shown in the bottom two figures of FIG.
1. Conversely, a second fuel concentration in the second prechamber
120 stage may be leaner if the first prechamber 110 stage is fuel
directly by a separate fuel admission point 130 as shown in the top
two figures of FIG. 1 than if the second prechamber 120 stage is
fueled directly by a separate fuel admission point 130 than as
shown in the bottom two figures of FIG. 1. Performance may be
improved in comparison to conventional single stage precombustion
chambers by either fueling the first prechamber 110 stage or the
second prechamber 120 stage directly. In certain embodiments, a
passive prechamber (PPC) spark plug may be used as the first
prechamber 110 stage. In certain embodiments, a fuel-fed second
prechamber 120 stage may be used in conjunction with a PPC spark
plug as the first prechamber stage 110. Exemplary non-limiting
examples of PPC spark plugs are disclosed in related U.S. patent
application Ser. No. 13/602,148 and International Patent
Application Numbers PCT/US2012/53568 and PCT/US2011/002012, which
are incorporated by reference herein.
[0036] In certain embodiments, the communication between the first
prechamber 110 stage, the second prechamber 120 stage and the main
combustion chamber may occur through one or more holes with a
predetermined relative pattern and angles. In certain embodiments,
the one or more holes may include one or more first stage holes 115
for communicating between the first prechamber 110 stage and the
second prechamber 120 stage and one or more second stage holes 125
for communicating between the second prechamber 120 stage and the
main combustion chamber. In certain embodiments, each of the one or
more first stage holes 115 may define a first stage hole axis 160
and each of the one or more second stage holes 125 may define a
second stage hole axis 160. Each first stage hole axis 160 and each
second stage hole axis 160 may define an index angle 610, a
penetration angle 600 and a rotational offset 620. The index angle
610, the penetration angle 600 and the rotational offset 620 of the
first stage holes 115 and the second stage holes 125 may be
selected to generate a first fuel concentration in the first
prechamber 110 stage that is higher than a second fuel
concentration in the second prechamber stage 120. In certain
embodiments, the volumes and aspect ratios of the two prechamber
stages, along with the location of the electrodes within the first
stage prechamber 110, the hole patterns, angles and the separate
fueling, may be selected to create a first fuel concentration in
the first prechamber 110 stage that is substantially higher than a
second fuel concentration in the second prechamber 120 stage.
[0037] FIG. 2 shows exemplary results for reduction of NOx output
achieved with a two-stage precombustion chamber system 100 with a
PPC spark plug as compared to a conventional precombustion chamber
with a conventional spark plug. The results shown in the FIG. 2
demonstrate that lower NOx emissions were achieved without penalty
in engine thermal efficiency with this non-optimized system.
Therefore, there is a great potential for an optimized two-stage
precombustion chamber system 100 with a PPC spark plug, to achieve
stable operation with leaner mixtures in the precombustion chamber
resulting in very low NOx emissions, much below the 0.5 g/bhp-hr
level.
[0038] In certain embodiments, the physical parameters shown in
FIGS. 3-13 may be varied alone or in combination to vary the first
fuel concentration in the first prechamber 110 stage and the second
fuel concentration in the second prechamber 120 stage to result in
a higher first fuel concentration than the second fuel
concentration.
[0039] As shown in FIG. 3, Total Volume 300 may be defined as the
volume of air inside the prechamber spark plug not including the
volume of the ports/holes.
[0040] As shown in FIG. 4, Volume Ahead of the Gap 400 may be
defined as the volume of air inside the prechamber spark plug from
the center of the gap to the endcap not including the volume of the
ports/holes.
[0041] As shown in FIG. 5, Volume Behind the Gap 500 may be defined
as the volume of air inside the prechamber spark plug between the
center of the gap and the rear of the prechamber not including the
volume of any ports/holes that may be at the rear of the
prechamber.
[0042] As shown in FIG. 6, the Penetration Angle 600 may be defined
as the angle between the plane perpendicular to the axis 160 of the
prechamber spark plug and the centerline of the port/hole.
[0043] As shown in FIG. 7, the Index Angle 610 may be defined as
the angle of rotation about the axis 160 of the prechamber spark
plug and the location on the port where the centerline of the port
meets the front plane of the prechamber spark plug.
[0044] As shown in FIG. 8, Rotational Offset 620 may be defined as
the perpendicular distance between the axis 160 of the prechamber
spark plug and the centerline of the port/hole (measured on the
plane at the front of the prechamber spark plug).
[0045] As shown in FIG. 9, the Pattern Radius 630 may be defined as
the perpendicular distance from the axis 160 of the prechamber
spark plug to the centerline of the port/hole, measured at the
front plane of the endcap.
[0046] As shown in FIG. 10, the Prechamber Ceiling Distance 640
from the Center Electrode may be defined as the distance along the
axis 160 of the prechamber spark plug from the top of the center
electrode to the inside of the endcap.
[0047] As shown in FIG. 11, the Port Length 650 may be defined as
the length of the port/hole, measured along the centerline of the
port/hole, from the inside of the endcap to the outside of the
endcap.
[0048] As shown in FIG. 12, the Port Diameter 660 may be defined as
the diameter of the port/hole.
[0049] As shown in FIG. 13, the Precombustion Chamber Insertion
Depth 670 may be defined as the distance from the firing deck to
the end of the prechamber spark plug. As shown, FIG. 9 assumes that
the firing deck is located at the end of the threads.
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