U.S. patent application number 14/160359 was filed with the patent office on 2014-05-15 for high-efficiency linear combustion engine.
This patent application is currently assigned to EtaGen, Inc.. The applicant listed for this patent is EtaGen, Inc.. Invention is credited to Shannon Miller, Adam Simpson, Matt Svrcek.
Application Number | 20140130771 14/160359 |
Document ID | / |
Family ID | 46063127 |
Filed Date | 2014-05-15 |
United States Patent
Application |
20140130771 |
Kind Code |
A1 |
Simpson; Adam ; et
al. |
May 15, 2014 |
HIGH-EFFICIENCY LINEAR COMBUSTION ENGINE
Abstract
Various embodiments of the present invention are directed toward
a linear combustion engine, comprising: a cylinder having a
cylinder wall and a pair of ends, the cylinder including a
combustion section disposed in a center portion of the cylinder; a
pair of opposed piston assemblies adapted to move linearly within
the cylinder, each piston assembly disposed on one side of the
combustion section opposite the other piston assembly, each piston
assembly including a spring rod and a piston comprising a solid
front section adjacent the combustion section and a gas section;
and a pair of linear electromagnetic machines adapted to directly
convert kinetic energy of the piston assembly into electrical
energy, and adapted to directly convert electrical energy into
kinetic energy of the piston assembly for providing compression
work during the compression stroke.
Inventors: |
Simpson; Adam; (San
Francisco, CA) ; Miller; Shannon; (Belmont, CA)
; Svrcek; Matt; (Redwood City, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EtaGen, Inc. |
Menlo Park |
CA |
US |
|
|
Assignee: |
EtaGen, Inc.
Menlo Park
CA
|
Family ID: |
46063127 |
Appl. No.: |
14/160359 |
Filed: |
January 21, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13298206 |
Nov 16, 2011 |
8662029 |
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14160359 |
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13102916 |
May 6, 2011 |
8453612 |
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13298206 |
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12953277 |
Nov 23, 2010 |
8413617 |
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13102916 |
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12953270 |
Nov 23, 2010 |
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12953277 |
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Current U.S.
Class: |
123/27R ;
123/46E |
Current CPC
Class: |
F02B 25/08 20130101;
F02B 71/00 20130101; F01B 7/02 20130101; F02B 1/12 20130101; F01B
11/001 20130101; H02K 35/02 20130101; F02B 63/041 20130101; F02B
71/04 20130101; F02B 75/282 20130101; F01B 11/007 20130101; H02K
7/1892 20130101 |
Class at
Publication: |
123/27.R ;
123/46.E |
International
Class: |
F02B 71/00 20060101
F02B071/00 |
Claims
1-45. (canceled)
46. A linear combustion engine, comprising: a cylinder comprising:
a combustion section, and a driver section comprising a compression
mechanism that is configured to provide at least some compression
work during a compression stroke of the engine; a piston assembly
disposed adjacent to the combustion section, the piston assembly
configured to move linearly; a linear electromagnetic machine
disposed outside of the cylinder, wherein the linear
electromagnetic machine is configured to directly convert kinetic
energy of the piston assembly into electrical energy, and
configured to directly convert electrical energy into kinetic
energy of the piston assembly; wherein the engine has a variable
expansion ratio greater than 50:1.
47. The linear combustion engine of claim 46, wherein the engine
has a variable compression ratio less than or equal to the variable
expansion ratio.
48. The linear combustion engine of claim 46, wherein a length of
the combustion section at top-dead-center is between 0.1 inches and
2 inches.
49. The linear combustion engine of claim 46, wherein the piston
assembly comprises: a piston; one or more piston seals coupled to
the piston; and a piston rod coupled to the piston, wherein the
piston rod is configured to move linearly inside and outside of the
cylinder.
50. The linear combustion engine of claim 49, wherein the piston
rod is further configured to move along bearings and is sealed by a
gas seal that is fixed to the cylinder.
51. The linear combustion engine of claim 46, wherein the piston
assembly comprises: two pistons; one or more piston seals coupled
to each of the two pistons; and a piston rod coupled to the two
pistons; wherein the piston assembly is encapsulated by the
cylinder and configured to move linearly within the cylinder.
52. The linear combustion engine of claim 46, wherein the linear
electromagnetic machine comprises: a stator; and a translator
attached to the piston assembly that moves linearly within the
stator.
53. The linear combustion engine of claim 46, wherein the linear
electromagnetic machine is selected from the group consisting of a
permanent magnet machine, an induction machine, a switched
reluctance machine, and a combination thereof.
54. The linear combustion engine of claim 46, wherein the
compression mechanism comprises a gas spring comprising a volume of
gas located in the driver section.
55. The linear combustion engine of claim 54, further comprising
one or more driver gas exchange ports configured to allow for an
exchange of gas in the driver section.
56. The linear combustion engine of claim 46, wherein the linear
electromagnetic machine is configured to apply an electromagnetic
force to the piston assembly for providing compression work during
the compression stroke.
57. The linear combustion engine of claim 46, further comprising an
injector configured to inject fuel.
58. The linear combustion engine of claim 57, wherein the injector
is configured to inject fuel directly into the combustion
section.
59. The linear combustion engine of claim 57, wherein the injector
is configured to inject fuel into an intake port.
60. The linear combustion engine of claim 46, further comprising
one or more exhaust ports configured to allow exhaust gases to
leave the cylinder.
61. The linear combustion engine of claim 46, wherein the engine
operates using a two-stroke piston cycle including a power stroke
and the compression stroke.
62. The linear combustion engine of claim 46, wherein during a
power stroke of the engine, a portion of the kinetic energy of the
piston assembly is converted into electrical energy by the linear
electromagnetic machine and another portion of the kinetic energy
does compression work on the driver section.
63. The linear combustion engine of claim 46, wherein the engine
operates using a four-stroke piston cycle including an intake
stroke, the compression stroke, a power stroke, and an exhaust
stroke.
64. The linear combustion engine of claim 46, wherein the
combustion section is configured to achieve compression
ignition.
65. The linear combustion engine of claim 46, wherein the
combustion section is configured to achieve spark ignition.
66. The linear combustion engine of claim 46, further comprising
one or more injector ports configured to allow fluids to enter the
cylinder.
67. The linear combustion engine of claim 1, further comprising one
or more intakes configured to allow an intake into the cylinder,
the intake comprising at least one of air, air and fuel mixtures,
and mixtures of air and at least one of fuel and combustion
products.
68. A linear combustion engine, comprising: a first cylinder
comprising a combustion section; a second cylinder comprising a
compression mechanism that is configured to provide at least some
compression work during a compression stroke of the engine; a
piston assembly disposed adjacent to the combustion section, the
piston assembly configured to move linearly; and a linear
electromagnetic machine disposed between the first cylinder and the
second cylinder, wherein the linear electromagnetic machine is
configured to directly convert kinetic energy of the piston
assembly into electrical energy, and configured to directly convert
electrical energy into kinetic energy of the piston assembly.
69. The linear combustion engine of claim 68, wherein the engine
has a variable compression ratio less than or equal to a variable
expansion ratio.
70. The linear combustion engine of claim 68, wherein a length of
the combustion section at top-dead-center is between 0.1 inches and
2 inches.
71. The linear combustion engine of claim 68, wherein the piston
assembly comprises: two pistons; two or more piston seals; and a
piston rod configured to move linearly between the first cylinder
and the second cylinder.
72. The linear combustion engine of claim 26, wherein the piston
rod is further configured to move along bearings and is sealed by a
gas seal that is fixed to the first cylinder.
73. The linear combustion engine of claim 68, wherein the linear
electromagnetic machine comprises: a stator; and a translator
attached to the piston assembly configured to move linearly within
the stator.
74. The linear combustion engine of claim 68, wherein the linear
electromagnetic machine is selected from the group consisting of a
permanent magnet machine, an induction machine, a switched
reluctance machine, and a combination thereof.
75. The linear combustion engine of claim 68, wherein the
compression mechanism comprises a gas spring comprising a volume of
gas located in a driver section of the second cylinder.
76. The linear combustion engine of claim 68, further comprising
one or more driver gas exchange ports configured to allow for an
exchange of gas in the driver section.
77. The linear combustion engine of claim 68, wherein the linear
electromagnetic machine is configured to apply an electromagnetic
force to the piston assembly for providing compression work during
the compression stroke.
78. The linear combustion engine of 1claim 68, further comprising
an injector configured to inject fuel.
79. The linear combustion engine of claim 78, wherein the injector
is configured to inject fuel directly into the combustion
section.
80. The linear combustion engine of claim 78, wherein the injector
is configured to inject fuel into an intake port.
81. The linear combustion engine of claim 68, further comprising
one or more exhaust ports configured to allow exhaust gases to
leave the first cylinder.
82. The linear combustion engine of claim 68, wherein during a
power stroke of the engine, a portion of the kinetic energy of the
piston assembly is converted into electrical energy by the linear
electromagnetic machine and another portion of the kinetic energy
does compression work on a driver section of the second
cylinder.
83. The linear combustion engine of claim 68, wherein the engine
operates using a four-stroke piston cycle including an intake
stroke, the compression stroke, a power stroke, and an exhaust
stroke.
84. The linear combustion engine of claim 68, wherein the
combustion section is configured to achieve compression
ignition.
85. The linear combustion engine of claim 68, wherein the
combustion section is configured to achieve spark ignition.
86. The linear combustion engine of claim 68, further comprising
one or more injector ports configured to allow a fluid to enter the
first cylinder.
87. The linear combustion engine of claim 68, further comprising
one or more intakes configured to allow an intake into the first
cylinder, the intake comprising at least one of air, air and fuel
mixtures, and mixtures of air and at least one of fuel and
combustion products.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 13/102,916 filed May 6, 2011, which is a
continuation-in-part of U.S. patent application Ser. Nos.
12/953,270 and 12/953,270 filed Nov. 23, 2010, the contents of
which are incorporated herein by reference in their entireties.
FIELD OF THE INVENTION
[0002] The present invention relates to high-efficiency linear
combustion engines and, more particularly, some embodiments relate
to high-efficiency linear combustion engines capable of reaching
high compression/expansion ratios by utilizing a free-piston engine
architecture in conjunction with a linear electromagnetic machine
for work extraction and an innovative combustion control
strategy.
DESCRIPTION OF THE RELATED ART
[0003] Engine power density and emission have improved over the
past 30 years; however overall efficiency has remained relatively
constant. It is well known in the engine community that increasing
the geometric compression ratio of an engine increases the engine's
theoretical efficiency limit. Additionally, increasing an engine's
geometric expansion ratio such that it is larger than its
compression ratio increases its theoretical efficiency limit even
further. For the sake of brevity, "compression ratio" and
"expansion ratio" is used to refer to "geometric compression ratio"
and "geometric expansion ratio," respectively.
[0004] FIG. 1 (prior art) shows the theoretical efficiency limits
of two cycles commonly used in internal combustion engines--Otto
and Atkinson. In particular, FIG. 1 is a comparison between the
ideal efficiencies of the Otto and Atkinson cycles as functions of
compression ratio. The model assumptions include: (i) the pressure
at bottom-dead-center ("BDC") is equal to one atmosphere; and (ii)
premixed, stoichiometric, ideal gas methane and air including
variable properties, dissociated products, and equilibrium during
expansion.
[0005] As shown in FIG. 1, the theoretical efficiency limits for
both cycles increase significantly with increasing compression
ratio. The ideal Otto cycle is broken down into three steps: 1)
isentropic compression, 2) adiabatic, constant volume combustion,
and 3) isentropic expansion to the original volume at BDC. The
expansion ratio for the Otto cycle is equal to its compression
ratio. The ideal Atkinson cycle is also broken down into three
steps: 1) isentropic compression, 2) adiabatic, constant volume
combustion, and 3) isentropic expansion to the original BDC
pressure (equal to one atmosphere in this example). The expansion
ratio for the Atkinson cycle is always greater than its compression
ratio, as shown in FIG. 1. Although the Atkinson cycle has a higher
theoretical efficiency limit than the Otto cycle for a given
compression ratio, it has a significantly lower energy density
(power per mass). In actual applications, there is a trade-off
between efficiency and energy density.
[0006] Well-designed/engineered engines in the market today
typically achieve brake efficiencies between 70-80% of their
theoretical efficiencies limits. The efficiencies of several
commercially available engines are shown in FIG. 2 (prior art).
Specifically, FIG. 2 is a comparison between the ideal Otto cycle
efficiency limit and several commercially available engines in the
market today. The model assumptions include premixed,
stoichiometric, ideal gas propane and air including variable
properties, dissociated products, and equilibrium during expansion.
The effective compression ratio is defined as the ratio of the
density of the gas at top-dead-center ("TDC") to the density of the
gas at BDC. The effective compression ratio provides a means to
compare boosted engines to naturally aspirated engines on a level
playing field. In order for a similarly well-designed engine to
have brake efficiencies above 50% (i.e., at least 70% of its
theoretical efficiency) an engine operating under the Otto cycle
must have a compression greater than 102 and an engine operating
under the Atkinson cycle must have a compression ratio greater than
14, which corresponds to an expansion ratio of 54, as illustrated
in FIG. 1.
[0007] It is difficult to reach high compression/expansion ratios
(above 30) in conventional, slider-crank, reciprocating engines
("conventional engines") because of the inherent architecture of
such engines. A diagram illustrating the architecture of
conventional engines and issues that limit them from going to high
compression ratios, is shown in FIG. 3 (prior art). Typical
internal combustion ("IC") engines have bore-to-stroke ratios
between 0.5-1.2 and compression ratios between 8-24. (Heywood, J.
(1988). Internal Combustion Engine Fundamentals. McGraw-Hill). As
an engine's compression ratio is increased while maintaining the
same bore-to-stroke ratio, the surface-to-volume ratio at
top-dead-center (TDC) increases, the temperature increases, and the
pressure increases. This has three major consequences: 1) heat
transfer from the combustion chamber increases, 2) combustion
phasing become difficult, and 3) friction and mechanical losses
increase. Heat transfer increases because the thermal boundary
layer becomes a larger fraction of the overall volume (i.e. the
aspect ratio at TDC gets smaller). The aspect ratio is defined as
the ratio of the bore diameter to the length of the combustion
chamber. Combustion phasing and achieving complete combustion is
difficult because of the small volume realized at TDC. Increased
combustion chamber pressure directly translates to increased
forces. These large forces can overload both the mechanical
linkages and piston rings.
[0008] While free-piston internal combustion engines are not new,
they have typically not been utilized or developed for achieving
compression/expansion ratios greater than 30:1, with the exception
of the work at Sandia National Laboratory. See, U.S. Pat. No.
6,199,519. There is a significant amount of literature and patents
around free piston engines. However, the literature is directed
toward free piston engines having short stroke lengths, and
therefore having similar issues to reciprocating engines when going
to high compression/expansion ratios--i.e., combustion control
issues and large heat transfer losses. Free-piston engine
configurations can be broken down into three categories: 1) two
opposed pistons, single combustion chamber, 2) single piston, dual
combustion chambers, and 3) single piston, single combustion
chamber. A diagram of the three common free-piston engine
configurations is shown in FIG. 4 (prior art). Single piston, dual
combustion chamber, free-piston engine configurations are limited
in compression ratio because the high forces experienced at high
compression ratios are not balanced, which can cause mechanical
instabilities.
[0009] As noted above, several free-piston engines have been
proposed in the research and patent literature. Of the many
proposed free-piston engines, there are only several that have been
physically implemented (to our knowledge). Research by Mikalsen and
Roskilly describes the free-piston engines at West Virginia
University, Sandia National Laboratory, and the Royal Institute of
Technology in Sweden. Mikalsen R. Roskilly A. P. A review of
free-piston engine history and applications. Applied Thermal
Engineering, 2007; 27:2339-2352. Other research efforts are
reportedly ongoing at the Czech Technical University
(http://www.lceproject.org/en/) INNAS BV in the Netherlands
(http://www.innas.com/) and Pempek Systems in Australia
(http://www.freepistonpower.com/). All of the known, physically
implemented free-piston engines have short stroke lengths, and
therefore have similar issues to reciprocating engines when going
to high compression/expansion ratios--i.e. combustion control
issues and large heat transfer losses. Additionally, all of the
engines except the prototype at Sandia National Laboratory
(Aichlmayr, H. T. Van Blarigan, P. Modeling and Experimental
Characterization of a Permanent Magnet Linear Alternator for
Free-Piston Engine Applications ASME Energy Sustainability
Conference San Francisco Calif., Jul. 19-23, 2009) and the
prototype developed by OPOC (International Patent Application WO
03/078835) have single piston, dual combustion chamber
configurations, and are therefore limited in compression ratio
because the high forces experienced at high compression ratios are
not balanced, which causes mechanical instabilities.
[0010] Given the inherent architecture limitations of conventional
engines described above, several manufacturers have attempted, and
are continuing attempts, to increase engine efficiency by going to
high effective compression ratios through the use of turbo- or
super-chargers. Boosting an engine via a turbo- or super-charger
provides a means to achieve a high effective compression ratio
while maintaining the same geometric compression ratio. Boosting an
engine does not avoid the issues caused by the higher-than-normal
pressures and forces experienced at and near TDC. Therefore, the
forces can overload both the mechanical linkages within the engine
(piston pin, piston rod, and crankshaft) causing mechanical failure
and the pressure-energized rings causing increased friction, wear,
or failure. Boosting an engine also typically leads to larger heat
transfer losses because the time spent at or near TDC (i.e., when
the temperatures are highest) is not reduced enough to account for
the higher-than-normal temperatures experienced at or near TDC.
BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION
[0011] Various embodiments of the present invention provide
high-efficiency linear combustion engines. Such embodiments remedy
the issues that prohibit conventional engines from reaching high
compression/expansion ratios by utilizing a free-piston engine
architecture in conjunction with a linear electromagnetic machine
for work extraction and an innovative combustion control strategy.
The invention disclosed herein provides a means to increase the
thermal efficiency of internal combustion engines to above 50% at
scales suitable for distributed generation and/or hybrid-electric
vehicles (5 kW-5 MW).
[0012] One embodiment of the invention is directed toward a linear
combustion engine, comprising: a cylinder having a cylinder wall
and a pair of ends, the cylinder including a combustion section
disposed in a center portion of the cylinder; a pair of opposed
piston assemblies adapted to move linearly within the cylinder,
each piston assembly disposed on one side of the combustion section
opposite the other piston assembly, each piston assembly including
a spring rod and a piston comprising a solid front section adjacent
the combustion section and a hollow back section comprising a gas
spring that directly provides at least some compression work during
a compression stroke of the engine; and a pair of linear
electromagnetic machines adapted to directly convert kinetic energy
of the piston assembly into electrical energy, and adapted to
directly convert electrical energy into kinetic energy of the
piston assembly for providing compression work during the
compression stroke; wherein the engine includes a variable
expansion ratio greater than 50:1.
[0013] Another embodiment of the invention is directed toward a
linear combustion engine, comprising: a cylinder having a cylinder
wall and a combustion section disposed at one end of the cylinder;
a piston assembly adapted to move linearly within the cylinder
including a spring rod and a piston comprising a solid front
section adjacent the combustion section and a hollow back section
comprising a gas spring that directly provides at least some
compression work during a compression stroke of the engine; and a
linear electromagnetic machine adapted to directly convert kinetic
energy of the piston assembly into electrical energy, and adapted
to directly convert electrical energy into kinetic energy of the
piston assembly for providing compression work during the
compression stroke; wherein the engine includes a variable
expansion ratio greater than 50:1.
[0014] Other features and aspects of the invention will become
apparent from the following detailed description, taken in
conjunction with the accompanying drawings, which illustrate, by
way of example, the features in accordance with embodiments of the
invention. The summary is not intended to limit the scope of the
invention, which is defined solely by the claims attached
hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention, in accordance with one or more
various embodiments, is described in detail with reference to the
following figures. The drawings are provided for purposes of
illustration only and merely depict typical or example embodiments
of the invention. These drawings are provided to facilitate the
reader's understanding of the invention and shall not be considered
limiting of the breadth, scope, or applicability of the invention.
It should be noted that for clarity and ease of illustration these
drawings are not necessarily made to scale.
[0016] FIG. 1 (prior art) is a chart illustrating the theoretical
efficiency limits of two cycles commonly used in internal
combustion engines.
[0017] FIG. 2 (prior art) is a chart comparing the ideal Otto cycle
efficiency limit and several commercially available engines in the
market today.
[0018] FIG. 3 (prior art) is a diagram illustrating the
architecture of conventional engines and issues that limit them
from going to high compression ratios.
[0019] FIG. 4 (prior art) is a diagram of the three common
free-piston engine configurations.
[0020] FIG. 5 is a chart illustrating a comparison between
experimental data from the prototype at Stanford University and the
ideal Otto cycle efficiency limit.
[0021] FIG. 6 is a cross-sectional drawing illustrating a
two-piston, two-stroke, integrated gas springs embodiment of an
internal combustion engine, in accordance with the principles of
the invention.
[0022] FIG. 7 is a diagram illustrating the two-stroke piston cycle
of the two-piston integrated gas springs engine of FIG. 6.
[0023] FIG. 8 is a cross-sectional drawing illustrating a
two-piston, four-stroke, integrated gas springs embodiment of an
internal combustion engine, in accordance with the principles of
the invention.
[0024] FIG. 9 is a diagram illustrating the four-stroke piston
cycle of the two-piston integrated gas springs engine of FIG. 8, in
accordance with the principles of the invention.
[0025] FIG. 10 is a cross-sectional drawing illustrating an
alternative two-piston, two-stroke, single-combustion section,
fully integrated gas springs and linear electromagnetic machine
engine, in accordance with the principles of the invention.
[0026] FIG. 11 is a cross-sectional drawing illustrating an
alternative two-piston, two-stroke, single-combustion section,
separated gas springs engine, in accordance with the principles of
the invention.
[0027] FIG. 12 is a cross-sectional drawing illustrating a
single-piston, two-stroke, integrated gas springs engine, in
accordance with the principles of the invention.
[0028] FIG. 13 is a diagram illustrating the two-stroke piston
cycle of the single-piston, two-stroke, integrated gas springs
engine of FIG. 12, in accordance with the principles of the
invention.
[0029] FIG. 14 is a cross-sectional drawing illustrating a
single-piston, four-stroke, integrated gas springs engine, in
accordance with the principles of the invention.
[0030] FIG. 15 is a diagram illustrating the four-stroke piston
cycle of the single-piston, two-stroke, integrated gas springs
engine of FIG. 14, in accordance with the principles of the
invention.
[0031] FIG. 16 is a cross-sectional drawing illustrating another
single-piston, two-stroke, single-combustion section, fully
integrated gas springs and linear electromagnetic machine engine,
in accordance with the principles of the invention.
[0032] FIG. 17 is a cross-sectional drawing illustrating another
single-piston, two-stroke, single-combustion section, separated gas
springs engine, in accordance with the principles of the
invention.
[0033] FIG. 18 is a cross-sectional view illustrating a
single-piston, two-stroke version of the IIGS architecture in
accordance with an embodiment of the invention.
[0034] FIG. 19 is a cross-sectional view illustrating an embodiment
of a gas spring rod in accordance with the principles of the
invention.
[0035] FIG. 20 is a cross-sectional view illustrating a two-piston,
two-stroke version of the IIGS engine in accordance with an
embodiment of the invention.
[0036] The figures are not intended to be exhaustive or to limit
the invention to the precise form disclosed. It should be
understood that the invention can be practiced with modification
and alteration, and that the invention be limited only by the
claims and the equivalents thereof.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
[0037] The present invention is generally directed toward
high-efficiency linear combustion engines capable of reaching high
compression/expansion ratios by utilizing a free-piston engine
architecture in conjunction with a linear electromagnetic machine
for work extraction and an innovative combustion control
strategy.
[0038] A single-shot, single-piston, prototype has been built and
operated at Stanford University. This prototype demonstrates
concept feasibility and achieves indicated-work efficiencies of
60%. A plot of certain experimental results is shown in FIG. 5. In
particular, FIG. 5 is a chart illustrating a comparison between
experimental data from the prototype at Stanford University and the
ideal Otto cycle efficiency limit. The model assumptions are as
follows: 0.3 equivalence ratio, diesel #2 and air including
variable properties, dissociated products, and equilibrium during
expansion.
[0039] Various embodiments of the invention are directed toward a
free-piston, linear combustion engine characterized by a thermal
efficiency greater than 50%. In at least one embodiment, the engine
comprises: (i) at least one cylinder, (ii) at least one piston
assembly per cylinder arranged for linear displacement within the
cylinder, (iii) at least one linear electromagnetic machine that
directly converts the kinetic energy of the piston assembly into
electrical energy, and (iv) at least one gas section that provides
at least some of the compression work during a compression stroke.
Additionally, in some configurations, the internal combustion
engine has the following physical characteristics: (i) a variable
expansion ratio greater than 50:1, (ii) a variable compression
ratio equal to or less than the expansion ratio, and (iii) a
combustion section length at TDC between 0.2 and 4 inches. It
should be noted, however, that further embodiments may include
various combinations of the above-identified features and physical
characteristics.
[0040] FIG. 6 is a cross-sectional drawing illustrating a
two-piston, two-stroke, integrated gas springs embodiment of an
internal combustion engine 100. This free-piston, internal
combustion engine 100 directly converts the chemical energy in a
fuel into electrical energy via a pair of linear electromagnetic
machines 200. As used herein, the term "fuel" refers to matter that
reacts with an oxidizer. Such fuels include, but are not limited
to: (i) hydrocarbon fuels such as natural gas, biogas, gasoline,
diesel, and biodiesel: (ii) alcohol fuels such as ethanol,
methanol, and butanol; and (iii) mixtures of any of the above. The
engines described herein are suitable for both stationary power
generation and portable power generation (e.g., for use in
vehicles).
[0041] FIG. 6 illustrates one embodiment of a two-piston,
two-stroke, integrated gas springs engine 100. In particular, the
engine 100 comprises one cylinder 105 with two opposed piston
assemblies 120 that meet at a combustion section 130 (or combustion
chamber) in the center of the cylinder 105. The placement of the
combustion section 130 in the center of the engine 100 balances the
combustion forces. Each piston assembly 120 comprises a piston 125,
piston seals 135, and a piston rod 145. The piston assemblies 120
are free to move linearly within the cylinder 105. The piston rods
145 move along bearings and are sealed by gas seals 150 that are
fixed to the cylinder 105. In the illustrated embodiment, the gas
seals 150 are piston rod seals. As used herein, the term "bearing"
refers to any part of a machine on which another part moves,
slides, or rotates, including but not limited to: slide bearings,
flexure bearings, ball bearings, roller bearings, gas bearings,
and/or magnetic bearings. Additionally, the term "surroundings"
refers to the area outside of the cylinder 105, including but not
limited to: the immediate environment, auxiliary piping, and/or
auxiliary equipment.
[0042] With further reference to FIG. 6, the volume between the
backside of the piston 125, piston rod 145, and the cylinder 105 is
referred to herein as the driver section 160. The driver section
160 may also be referred to herein as the "gas section", "gas
springs" or "gas springs section," Each driver section 160 is
sealed from the surroundings and combustion section 130 by piston
rod seal 150 and piston seals 135. In the illustrated embodiment,
the gas in the driver section 160 acts a fly wheel (i.e., a gas
spring) during a cycle to provide at least some of the compression
work during a compression stroke. Accordingly, some embodiments of
the invention feature gas springs for providing work. Other
embodiments include a highly efficient linear alternator operated
as a motor, and do not require gas springs for generating
compression work.
[0043] In some embodiments, in order to obtain high thermal
efficiencies, the engine 100 has a variable expansion ratio greater
than 50:1. In additional embodiments, the variable expansion ratio
is greater than 75:1. In further embodiments, the variable
expansion ratio is greater than 100:1. In addition, some
embodiments feature a compression ratio equal to or less than the
expansion ratio, and a combustion section length at TDC between
0.2-4 inches. As used herein, "combustion section length at TDC" is
the distance between the front faces of the two pistons 125 at
TDC.
[0044] The above specifications dictate that the engine 100 have a
stroke length that is significantly longer than in conventional
engines, wherein the term "stroke length" refers to the distance
traveled by the each piston 125 between TDC and BDC. Combustion
ignition can be achieved via compression ignition and/or spark
ignition. Fuel can be directly injected into the combustion chamber
130 via fuel injectors ("direct injection") and/or mixed with air
prior to and/or during air intake ("premixed injection"). The
engine 100 can operate with lean, stoichiometric, or rich
combustion using liquid and/or gaseous fuels.
[0045] With continued reference to FIG. 6, the cylinder 105
includes exhaust/injector ports 170, intake ports 180, driver gas
removal ports 185, and driver gas make-up ports 190, for exchanging
matter (solid, liquid, gas, or plasma) with the surroundings. As
used herein, the term "port" includes any opening or set of
openings (e.g., a porous material) which allows matter exchange
between the inside of the cylinder 105 and its surroundings. Some
embodiments do not require all of the ports depicted in FIG. 6. The
number and types of ports depends on the engine configuration,
injection strategy, and piston cycle (e.g., two- or four-stroke
piston cycles). For this two-piston, two-stroke embodiment,
exhaust/injector ports 170 allow exhaust gases and fluids to enter
and leave the cylinder, intake ports 180 are for the intake of air
and/or air/fuel mixtures, driver gas removal ports 185 are for the
removal of driver gas, and driver gas make-up ports 190 are for the
intake of make-up gas for the driver section 160. The location of
the various ports is not necessarily fixed. For example, in the
illustrated embodiment, exhaust/injector ports 170 are located
substantially at the midpoint of the cylinder. However, these ports
may alternatively be located away from the midpoint adjacent the
intake ports 180.
[0046] The above-described ports may or may not be opened and
closed via valves. The term "valve" may refer to any actuated flow
controller or other actuated mechanism for selectively passing
matter through an opening, including but not limited to: ball
valves, plug valves, butterfly valves, choke valves, check valves,
gate valves, leaf valves, piston valves, poppet valves, rotary
valves, slide valves, solenoid valves, 2-way valves, or 3-way
valves. Valves may be actuated by any means, including but not
limited to: mechanical, electrical, magnetic, camshaft-driven,
hydraulic, or pneumatic means. In most cases, ports are required
for exhaust, driver gas removal, and driver gas make-up. In
embodiments where direct injection is the desired ignition
strategy, injector ports and air intake ports are also required. In
embodiments where premixed compression ignition or premixed spark
ignition is the desired combustion strategy, air/fuel intake ports
may also be required. In embodiments where a hybrid premixed/direct
injection strategy with compression ignition and/or spark ignition
is the desired combustion strategy, injector ports and air/fuel
intake ports may also be required. In all engine configurations,
exhaust gas from a previous cycle can be mixed with the intake air
or air/fuel mixture for a proceeding cycle. This process it is
called exhaust gas recirculation (EGR) and can be utilized to
moderate combustion timing and peak temperatures.
[0047] With further reference to FIG. 6, the engine 100 further
comprises a pair of linear electromagnetic machines (LEMs) 200 for
directly converting the kinetic energy of the piston assemblies 120
into electrical energy. Each LEM 200 is also capable of directly
converting electrical energy into kinetic energy of the piston
assembly 120 for providing compression work during a compression
stroke. As illustrated, the LEM 200 comprises a stator 210 and a
translator 220. Specifically, the translator 220 is attached to the
piston rod 145 and moves linearly within the stator 210, which is
stationary. The volume between the translator 220 and stator 210 is
called the air gap. The LEM 200 may include any number of
configurations. FIG. 6 shows one configuration in which the
translator 220 is shorter than stator 210. However, the translator
220 could be longer than the stator 210, or they could be
substantially the same length. In addition, the LEM 200 can be a
permanent magnet machine, an induction machine, a switched
reluctance machine, or some combination of the three. The stator
210 and translator 220 can each include magnets, coils, iron, or
some combination thereof. Since the LEM 200 directly transforms the
kinetic energy of the pistons to and from electrical energy (i.e.,
there are no mechanical linkages), the mechanical and frictional
losses are minimal compared to conventional engine-generator
configurations.
[0048] The embodiment shown in FIG. 6 operates using a two-stroke
piston cycle. A diagram illustrating the two-stroke piston cycle
250 of the two-piston integrated gas springs engine 100 of FIG. 6
is illustrated in FIG. 7. As used herein, the term "piston cycle"
refers to any series of piston movements which begin and end with
the piston 125 in substantially the same configuration. One common
example is a four-stroke piston cycle, which comprises an intake
stroke, a compression stroke, a power (expansion) stroke, and an
exhaust stroke. Additional alternate strokes may form part of a
piston cycle as described throughout this disclosure. A two-stroke
piston cycle is characterized as having a power (expansion) stroke
and a compression stroke.
[0049] As illustrated in FIG. 7, the engine exhausts combustion
products (though exhaust ports 170) and intakes air or an air/fuel
mixture or an air/fuel/combustion products mixture (through intake
ports 180) near BDC between the power and compression strokes. This
process may be referred to herein as "breathing" or "breathing at
or near BDC." It will be appreciated by those of ordinary skill in
the art that many other types of port and breathing configurations
are possible without departing from the scope of the invention.
When at or near BDC, and if the driver section is to be used to
provide compression work, the pressure of the gas within the driver
section 160 is greater than the pressure of the combustion section
130, which forces the pistons 125 inwards toward each other. The
gas in the driver section 160 can be used to provide at least some
of the energy required to perform a compression stroke. The LEM 200
may also provide some of the energy required to perform a
compression stroke.
[0050] The amount of energy required to perform a compression
stroke depends on the desired compression ratio, the pressure of
the combustion section 130 at the beginning of the compression
stroke, and the mass of the piston assembly 120. A compression
stroke continues until combustion occurs, which is at a time when
the velocity of the piston 125 is at or near zero. The point at
which the velocities of the pistons 125 are equal to zero marks
their TDC positions for that cycle. Combustion causes an increase
in the temperature and pressure within the combustion section 130,
which forces the piston 125 outward toward the LEM 200. During a
power stroke, a portion of the kinetic energy of the piston
assembly 120 is converted into electrical energy by the LEM 200 and
another portion of the kinetic energy does compression work on the
gas in the driver section 160. A power stroke continues until the
velocities of the pistons 125 are zero, which marks their BDC
positions for that cycle.
[0051] FIG. 7 illustrates one port configuration for breathing in
which the intake ports 180 are in front of both pistons near BDC
and the exhaust ports 170 are near TDC. There are various possible
alternative port configurations, such as, but not limited to,
locating the exhaust ports 170 in front of one piston 125 near BDC,
and locating the intake ports 180 in front of the other piston 125
near BDC--allowing for what is called uni-flow scavenging, or
uni-flow breathing. The opening and closing of the exhaust ports
170 and intake ports 180 are independently controlled. The location
of the exhaust ports 170 and intake ports 180 can be chosen such
that a range of compression ratios and/or expansion ratios are
possible. The times in a cycle when the exhaust ports 170 and
intake ports 180 are activated (opened and closed) can be adjusted
during and/or between cycles to vary the compression ratio and/or
expansion ratio and/or the amount of combustion product retained in
the combustion section 130 at the beginning of a compression
stroke. Retaining combustion gases in the combustion section 130 is
called residual gas trapping (RGT) and can be utilized to moderate
combustion timing and peak temperatures.
[0052] During the piston cycle, gas could potentially transfer past
the piston seals 135 between the combustion section 130 and driver
section 160. This gas transfer is referred to as "blow-by." Blow-by
gas could contain air and/or fuel and/or combustion products. The
engine 100 is designed to manage blow-by gas by having at least two
ports in each driver section 160--one port 185 for removing driver
gas and the another port 190 for providing make-up driver gas. The
removal of driver gas and the intake of make-up driver gas are
independently controlled and occur in such a way to minimize losses
and maximize efficiency.
[0053] FIG. 7 shows one strategy for exchanging driver gas in which
the removal of driver gas occurs at some point during the expansion
stroke and the intake of make-up driver gas occurs at some point
during the compression stroke. The removal and intake of driver gas
could also occur in the reverse order of strokes or during the same
stroke. Removed driver gas can be used as part of the intake for
the combustion section 130 during a proceeding combustion cycle.
The amount of gas in the driver section 160 can be adjusted to vary
the compression ratio and/or expansion ratio. The expansion ratio
is defined as the ratio of the volume of combustion section 130
when the pistons 125 have zero velocity after the power stroke to
the volume of the combustion section 130 when the pistons 125 have
zero velocity after the compression stroke. The compression ratio
is defined as the ratio of the volume of the combustion section 130
when the pressure within the combustion section 130 begins to
increase due to the inward motion of the pistons 125 to the ratio
of the volume of the combustion section 130 when the pistons 125
have zero velocity after the compression stroke.
[0054] Combustion is optimally controlled by moderating (e.g.,
cooling) the temperature of the gas within the combustion section
130 prior to combustion. Temperature control can be achieved by
pre-cooling the combustion section intake gas and/or cooling the
gas within the combustion section 130 during the compression
stroke. Optimal combustion occurs when the combustion section 130
reaches the volume at which the thermal efficiency of the engine
100 is maximized. This volume is referred to as optimal volume, and
it can occur before or after TDC. Depending on the combustion
strategy (ignition and injection strategy), the combustion section
intake gas could be air, an air/fuel mixture, or an
air/fuel/combustion products mixture (where the combustion products
are from EGR and/or recycled driver gas), and the gas within the
combustion section 130 could be air, an air/fuel mixture, or an
air/fuel/combustion products mixture (where the combustion products
are from EGR and/or RGT and/or recycled driver gas).
[0055] When compression ignition is the desired ignition strategy,
optimal combustion is achieved by moderating the temperature of the
gas within the combustion section 130 such that it reaches its
auto-ignition temperature at the optimal volume. When spark
ignition is the desired ignition strategy, optimal combustion is
achieved by moderating the temperature of the gas within the
combustion section 130 such that it remains below its auto-ignition
temperature before a spark fires at optimal volume. The spark is
externally controlled to fire at the optimal volume. The combustion
section intake gas can be pre-cooled by means of a refrigeration
cycle. The gas within the combustion section 130 can be cooled
during a compression stroke by injecting a liquid into the
combustion section 130 which then vaporizes. The liquid can be
water and/or another liquid such as, but not limited to, a fuel or
a refrigerant. The liquid can be cooled prior to injection into the
combustion section 130.
[0056] For a given engine geometry and exhaust and intake port
locations, the power output from the engine 100 can be varied from
cycle to cycle by varying the air/fuel ratio and/or the amount of
combustion products in the combustion section 130 prior to
combustion and/or the compression ratio and/or the expansion ratio.
For a given air/fuel ratio in a cycle, the peak combustion
temperature can be controlled by varying the amount of combustion
products from a previous cycle that are present in the combustion
section gas prior to combustion. Combustion products in the
combustion section gas prior to combustion can come from EGR and/or
RGT and/or recycling driver gas. Piston synchronization is achieved
through a control strategy that uses information about the piston
positions, piston velocities, combustion section composition, and
cylinder pressures, to adjust the LEMs' and driver sections'
operating characteristics.
[0057] The configuration of FIGS. 6 and 7 includes a single unit
referred to as the engine 100 and defined by the cylinder 105, the
piston assemblies 120 and the LEMs 200. However, many units can be
placed in parallel, which could collectively be referred to as "the
engine." Some embodiments of the invention are modular such that
they can be arranged to operate in parallel to enable the scale of
the engine to be increased as needed by the end user. Additionally,
not all units need be the same size or operate under the same
conditions (e.g., frequency, stoichiometry, or breathing). When the
units are operated in parallel, there exists the potential for
integration between the engines, such as, but not limited to, gas
exchange between the units and/or feedback between the units' LEMs
200.
[0058] The free-piston architecture allows for large and variable
compression and expansion ratios while maintaining sufficiently
large volume at TDC to minimize heat transfer and achieve adequate
combustion. In addition, the pistons spend less time at and near
TDC than they would if they were mechanically linked to a
crankshaft. This helps to minimize heat transfer (and maximize
efficiency) because less time is spent at the highest temperatures.
Furthermore, since the free-piston architecture does not have
mechanical linkages, the mechanical and frictional losses are
minimal compared to conventional engines. Together, the large and
variable compression and expansion ratios, the sufficiently large
volume at TDC, the direct conversion of kinetic energy to
electrical energy by the LEM 200, the inherently short time spent
at and near TDC, and the ability to control combustion, enable the
engine 100 to achieve thermal efficiencies greater than 50%.
[0059] During operation, the losses within the engine 100 include:
combustion losses, heat transfer losses, electricity conversion
losses, frictional losses, and blow-by losses. In some embodiments
of the invention, combustion losses are minimized by performing
combustion at high internal energy states, which is achieved by
having the ability to reach high compression ratios while
moderating combustion section temperatures. Heat transfer losses
are minimized by having a sufficiently large volume at and near
when combustion occurs such that the thermal boundary layer is a
small fraction of the volume. Heat transfer losses are also
minimized by spending less time at high temperature using a
free-piston profile rather than a slider-crank profile. Frictional
losses are minimized because there are no mechanical linkages.
Blow-by losses are minimized by having well-designed piston seals
and using driver gas that contains unburned fuel as part of the
intake for the next combustion cycle.
[0060] As stated, the embodiment described above with respect to
FIGS. 6 and 7 comprises a two-piston, single-combustion section,
two-stroke internal combustion engine 100. Described below, and
illustrated in the corresponding figures, are several alternative
embodiments. These embodiments are not meant to be limiting. As
would be appreciated by those of ordinary skill in the art, various
modifications and alternative configurations may be utilized, and
other changes may be made, without departing from the scope of the
invention. Unless otherwise stated, the physical and operational
characteristics of the embodiments described below are similar to
those described in the embodiment of FIGS. 6 and 7, and like
elements have been labeled accordingly. Furthermore, all
embodiments may be configured in parallel (i.e., in multiple-unit
configurations for scaling up) as set forth above.
[0061] FIG. 8 illustrates a four-stroke embodiment of the invention
comprising a two-piston, four-stroke, integrated gas springs engine
300. The main physical difference between the four-stroke engine
300 of FIG. 8 and the two-stroke engine 100 of FIG. 6 involves the
location of the ports. In particular, in the four-stroke engine
300, the exhaust, injector, and intake ports 370 are located at
and/or near the midpoint of the cylinder 105 between the two
pistons 125.
[0062] FIG. 9 illustrates the four-stroke piston cycle 400 for the
two-piston integrated gas springs engine 300 of FIG. 8. A
four-stroke piston cycle is characterized as having a power
(expansion) stroke, an exhaust stroke, an intake stroke, and a
compression stroke. A power stroke begins following combustion,
which occurs at the optimal volume, and continues until the
velocities of the pistons 125 are zero, which marks their
power-stroke BDC positions for that cycle.
[0063] During a power stroke, a portion of the kinetic energy of
the piston assemblies 120 is converted into electrical energy by
the LEM 200, and another portion of the kinetic energy does
compression work on the gas in the driver section 160. When at and
near the power-stroke BDC, and if the driver section is to provide
at least some of the compression work, the pressure of the gas in
the driver section 160 is greater than the pressure of the gas in
the combustion section 130, which forces the pistons 125 inwards
toward the midpoint of the cylinder 105. In the illustrated
embodiment, the gas in the driver section 160 can be used to
provide at least some of the energy required to perform an exhaust
stroke. In some cases, the LEM 200 may also provide some of the
energy required to perform an exhaust stroke. Exhaust ports 370
open at some point at or near the power-stroke BDC, which can be
before or after an exhaust stroke begins. An exhaust stroke
continues until the velocities of the pistons 125 are zero, which
marks their exhaust-stroke TDC positions for that cycle. Exhaust
ports 370 close at some point before the pistons 125 reach their
exhaust-stroke TDC positions. Therefore, at least some combustion
products remain in the combustion section 130. This process is
referred to as residual gas trapping.
[0064] With further reference to FIG. 9, at and near the
exhaust-stroke TDC, the pressure of the combustion section 130 is
greater than the pressure of the driver section 160, which forces
the pistons 125 outwards. The trapped residual gas acts a gas
spring to provide at least some of the energy required to perform
an intake stroke. The LEM 200 may also provide some of the energy
required to perform an intake stroke. Intake ports 370 open at some
point during the intake stroke after the pressure within the
combustion section 130 is below the pressure of the intake gas. An
intake stroke continues until the velocities of the pistons 125 are
zero, which marks their intake-stroke BDC positions for that cycle.
The intake-stroke BDC positions for a given cycle do not
necessarily have to be the same as the power-stroke BDC positions.
Intake ports 370 close at some point at or near intake-stroke BDC.
A compression stroke continues until combustion occurs, which is at
a time when the velocities of the pistons 125 are at or near zero.
The positions of the pistons 125 at which their velocities equal
zero mark their compression-stroke TDC positions for that cycle. At
and near the compression-stroke TDC, the pressure of the gas in the
driver section 160 is greater than the pressure of the gas in the
combustion section 130, which forces the pistons 125 inwards. The
gas in the driver section 160 is used to provide at least some of
the energy required to perform a compression stroke. The LEM 200
may also provide some of the energy required to perform a
compression stroke.
[0065] FIG. 9 shows one strategy for exchanging driver gas in which
the removal of driver gas occurs at some point during the expansion
stroke and the intake of make-up driver gas occurs at some point
during the compression stroke. As in the two-stroke embodiment, the
removal and intake of driver gas could also occur in the reverse
order of strokes or during the same stroke. However, since the
four-stroke embodiment has a separate exhaust stroke, which
requires less energy to perform than a compression stroke,
regulating the amount of air in the driver section 160 may require
a different approach, depending on how much the LEM 200 is used to
provide and extract energy during the four strokes.
[0066] FIG. 10 illustrates a second two-piston, two-stroke, fully
gas springs and integrated linear electromagnetic machine
embodiment of an internal combustion engine 500. Similar to the
engine 100 of FIG. 10 engine 500 comprises a cylinder 105, two
opposed piston assemblies 520, and a combustion section 130 located
in the center of the cylinder 105. In the illustrated
configuration, each piston assembly 520 comprises two pistons 525,
piston seals 535, and a piston rod 545. Unlike previous
embodiments, the piston assemblies 520 and translators 620 are
completely located within the cylinder, and the LEM 600 (including
stator 610) is disposed around the outside perimeter of the
cylinder 105. The piston assemblies 520 are free to move linearly
within the cylinder 105. The cylinder 105 further includes
exhaust/injector ports 170, intake ports 180, driver gas removal
ports 185, and driver gas make-up ports 190. With further reference
to FIG. 10, this embodiment can operate using a two- or four-stroke
piston cycle using the same methodology set forth above with
respect to FIGS. 7, and 9.
[0067] FIG. 11 illustrates a third two-piston, two-stroke,
single-combustion section, separated gas springs embodiment of an
internal combustion engine 700. Similar to the engine 100 of FIG.
6, engine 700 comprises a main cylinder 105, two opposed piston
assemblies 120, and a combustion section 130 located in the center
of the cylinder 705. However, the illustrated engine 700 has
certain physical differences when compared with engine 100.
Specifically, engine 700 includes a pair of outer cylinders 705
that contain additional pistons 135, and the LEMs 200 are disposed
between the main cylinder 105 and the outer cylinders 705. Each
outer cylinder 705 includes a driver section 710 located between
the piston 125 and the distal end of the cylinder 705 and a driver
back section 720 disposed between the piston 125 and the proximal
end of cylinder 705. Additionally, cylinder 105 includes a pair of
combustion back sections 730 disposed between the pistons 125 and
the distal ends of the cylinder 105. The driver back section 720
and combustion back section 730 are maintained at or near
atmospheric pressure. As such, the driver back section 720 is not
sealed (i.e., linear bearing 740 is provided with no gas seal),
whereas the combustion back section 730 is sealed (i.e., via seal
150), but has ports for removal of blow-by gas (i.e., blow-by
removal port 750) and for make-up gas (i.e., make-up air port 760).
In the illustrated configuration, each piston assembly 120
comprises two pistons 125, piston seals 135, and a piston rod 145.
The piston assemblies 120 are free to move linearly between the
main cylinder 105 and the outer cylinders 705, as depicted in FIG.
11. The piston rods 145 move along bearings and are sealed by gas
seals 150 that are fixed to the main cylinder 105. The cylinder 105
further includes exhaust/injector ports 170 and intake ports 180.
However, the driver gas removal ports 185 and driver gas make-up
ports 190 are located on a pair of outer cylinders 705 that contain
one of the two pistons 125 of each piston assembly 120. With
further reference to FIG. 11, this embodiment can operate using a
two- or four-stroke piston cycle using the same methodology set
forth above with respect to FIGS. 7 and 9.
[0068] FIG. 12 illustrates one embodiment of a single-piston,
two-stroke, integrated gas springs engine 1000. In particular, the
engine 1000 comprises a vertically disposed cylinder 105 with
piston assembly 120 dimensioned to move within the cylinder 105 in
response to reactions within combustion section 130 (or combustion
chamber) near the bottom end of the cylinder 105. An impact plate
230 is provided at the bottom end of the vertically disposed
cylinder to provide stability and impact resistance during
combustion. Piston assembly 120 comprises a piston 125, piston
seals 135, and a piston rod 145. The piston assembly 120 is free to
move linearly within the cylinder 105. The piston rod 145 moves
along bearings and is sealed by gas seals 150 that are fixed to the
cylinder 105. In the illustrated embodiment, the gas seals 150 are
piston rod seals.
[0069] With further reference to FIG. 12, the volume between the
backside of the piston 125, piston rod 145, and the cylinder 105 is
referred to herein as the driver section 160. The driver section
160 may also be referred to herein as the "gas springs" or "gas
springs section." Driver section 160 is sealed from the
surroundings and combustion section 130 by piston rod seal 150 and
piston seals 135. In the illustrated embodiment, the gas in the
driver section 160 acts a fly wheel (i.e., a gas spring) during a
cycle to provide at least some of the compression work during a
compression stroke. Accordingly, some embodiments of the invention
feature gas springs for providing work. Other embodiments include a
highly efficient linear alternator operated as a motor, and do not
require gas springs for generating compression work.
[0070] In some embodiments, in order to obtain high thermal
efficiencies, the engine 1000 has a variable expansion ratio
greater than 50:1. In additional embodiments, the variable
expansion ratio is greater than 75:1. In further embodiments, the
variable expansion ratio is greater than 100:1. In addition, some
embodiments feature a compression ratio equal to or less than the
expansion ratio, and a combustion section length at TDC between
0.1-2 inches. As used herein, "combustion section length at TDC" is
the distance between the combustion section head and front face of
the piston 125.
[0071] The above specifications dictate that the engine 1000 have a
stroke length that is significantly longer than in conventional
engines, wherein the term "stroke length" refers to the distance
traveled by the piston 125 between TDC and BDC. The stroke is the
distance traveled by the piston between TDC and BDC. Combustion
ignition can be achieved via compression ignition and/or spark
ignition. Fuel can be directly injected into the combustion chamber
130 via fuel injectors ("direct injection") and/or mixed with air
prior to and/or during air intake ("premixed injection"). The
engine 1000 can operate with lean, stoichiometric, or rich
combustion using liquid and/or gaseous fuels.
[0072] With continued reference to FIG. 12, the cylinder 105
includes exhaust/injector ports 170, intake ports 180, driver gas
removal port 185, and driver gas make-up port 190, for exchanging
matter (solid, liquid, gas, or plasma) with the surroundings. As
used herein, the term "port" includes any opening or set of
openings (e.g., a porous material) which allows matter exchange
between the inside of the cylinder 105 and its surroundings. Some
embodiments do not require all of the ports depicted in FIG. 12.
The number and types of ports depends on the engine configuration,
injection strategy, and piston cycle (e.g., two- or four-stroke
piston cycles). For this single-piston, two-stroke embodiment,
exhaust/injector ports 170 allow exhaust gases and fluids to enter
and leave the cylinder, intake ports 180 are for the intake of air
and/or air/fuel mixtures, driver gas removal port 185 is for the
removal of driver gas, and driver gas make-up port 190 is for the
intake of make-up gas for the driver section 160. The location of
the various ports is not necessarily fixed. For example, in the
illustrated embodiment, exhaust/injector ports 170 are located
substantially at the midpoint of the cylinder. However, these ports
may alternatively be located away from the midpoint adjacent the
intake ports 180.
[0073] With further reference to FIG. 12 the engine 1000 further
comprises a linear electromagnetic machine (LEM) 200 for directly
converting the kinetic energy of the piston assembly 120 into
electrical energy. LEM 200 is also capable of directly converting
electrical energy into kinetic energy of the piston assembly 120
for providing compression work during a compression stroke. As
illustrated, the LEM 200 comprises a stator 210 and a translator
220. Specifically, the translator 220 is attached to the piston rod
145 and moves linearly within the stator 210, which is stationary.
The volume between the translator 220 and stator 210 is called the
air gap. The LEM 200 may include any number of configurations. FIG.
6 shows one configuration in which the translator 220 is shorter
than stator 210. However, the translator 220 could be longer than
the stator 210, or they could be substantially the same length. In
addition, the LEM 200 can be a permanent magnet machine, an
induction machine, a switched reluctance machine, or some
combination of the three. The stator 210 and translator 220 can
each include magnets, coils, iron, or some combination thereof.
Since the LEM 200 directly transforms the kinetic energy of the
pistons to and from electrical energy (i.e., there are no
mechanical linkages), the mechanical and frictional losses are
minimal compared to conventional engine-generator
configurations.
[0074] The embodiment shown in FIG. 12 operates using a two-stroke
piston cycle. A diagram illustrating the two-stroke piston cycle
1250 of the single-piston integrated gas springs engine 1000 of
FIG. 12 is illustrated in FIG. 13. The engine exhausts combustion
products (though exhaust ports 170) and intakes air or an air/fuel
mixture or an air/fuel/combustion products mixture (through intake
ports 180) near BDC between the power and compression strokes. This
process may be referred to herein as "breathing" or "breathing at
or near BDC." It will be appreciated by those of ordinary skill in
the art that many other types of port and breathing configurations
are possible without departing from the scope of the invention.
When at or near BDC, and if the driver section is to be used to
provide compression work, the pressure of the gas within the driver
section 160 is greater than the pressure of the combustion section
130, which forces the pistons 125 inwards toward each other. The
gas in the driver section 160 can be used to provide at least some
of the energy required to perform a compression stroke. The LEM 200
may also provide some of the energy required to perform a
compression stroke.
[0075] The amount of energy required to perform a compression
stroke depends on the desired compression ratio, the pressure of
the combustion section 130 at the beginning of the compression
stroke, and the mass of the piston assembly 120. A compression
stroke continues until combustion occurs, which is at a time when
the velocity of the piston 125 is at or near zero. The point at
which the velocities of the piston 125 is equal to zero marks their
TDC positions for that cycle. Combustion causes an increase in the
temperature and pressure within the combustion section 130, which
forces the piston 125 outward toward the LEM 200. During a power
stroke, a portion of the kinetic energy of the piston assembly 120
is converted into electrical energy by the LEM 200 and another
portion of the kinetic energy does compression work on the gas in
the driver section 160. A power stroke continues until the
velocities of the piston 125 is zero, which marks their BDC
positions for that cycle.
[0076] FIG. 13 illustrates one port configuration 1300 for
breathing in which the intake ports 180 are in front of the piston
near BDC and the exhaust ports 170 are near TDC. The opening and
closing of the exhaust ports 170 and intake ports 180 are
independently controlled. The location of the exhaust ports 170 and
intake ports 180 can be chosen such that a range of compression
ratios and/or expansion ratios are possible. The times in a cycle
when the exhaust ports 170 and intake ports 180 are activated
(opened and closed) can be adjusted during and/or between cycles to
vary the compression ratio and/or expansion ratio and/or the amount
of combustion product retained in the combustion section 130 at the
beginning of a compression stroke. Retaining combustion gases in
the combustion section 130 is called residual gas trapping (RGT)
and can be utilized to moderate combustion timing and peak
temperatures.
[0077] During the piston cycle, gas could potentially transfer past
the piston seals 135 between the combustion section 130 and driver
section 160. This gas transfer is referred to as "blow-by." Blow-by
gas could contain air and/or fuel and/or combustion products. The
engine 1000 is designed to manage blow-by gas by having at least
two ports in driver section 160--one port 185 for removing driver
gas and the another port 190 for providing make-up driver gas. The
removal of driver gas and the intake of make-up driver gas are
independently controlled and occur in such a way to minimize losses
and maximize efficiency.
[0078] FIG. 13 shows one strategy for exchanging driver gas in
which the removal of driver gas occurs at some point during the
expansion stroke and the intake of make-up driver gas occurs at
some point during the compression stroke. The removal and intake of
driver gas could also occur in the reverse order of strokes or
during the same stroke. Removed driver gas can be used as part of
the intake for the combustion section 130 during a proceeding
combustion cycle. The amount of gas in the driver section 160 can
be adjusted to vary the compression ratio and/or expansion ratio.
The expansion ratio is defined as the ratio of the volume of
combustion section 130 when the piston 125 has zero velocity after
the power stroke to the volume of the combustion section 130 when
the piston 125 has zero velocity after the compression stroke. The
compression ratio is defined as the ratio of the volume of the
combustion section 130 when the pressure within the combustion
section 130 begins to increase due to the inward motion of the
piston 125 to the ratio of the volume of the combustion section 130
when the piston 125 has zero velocity after the compression
stroke.
[0079] The configuration of FIGS. 12 and 13 includes a single unit
referred to as the engine 1000 and defined by the cylinder 105, the
piston assembly 120 and the LEM 200. However, many units can be
placed in parallel, which could collectively be referred to as "the
engine," Some embodiments of the invention are modular such that
they can be arranged to operate in parallel to enable the scale of
the engine to be increased as needed by the end user. Additionally,
not all units need be the same size or operate under the same
conditions (e.g., frequency, stoichiometry, or breathing). When the
units are operated in parallel, there exists the potential for
integration between the engines, such as, but not limited to, gas
exchange between the units and/or feedback between the units' LEM
200.
[0080] As stated, the embodiment described above with respect to
FIGS. 12 and 13 comprises a single-piston, single-combustion
section, two-stroke internal combustion engine 1000. Described
below, and illustrated in the corresponding figures, are several
alternative embodiments. These embodiments are not meant to be
limiting. As would be appreciated by those of ordinary skill in the
art, various modifications and alternative configurations may be
utilized, and other changes may be made, without departing from the
scope of the invention. Unless otherwise stated, the physical and
operational characteristics of the embodiments described below are
similar to those described in the embodiment of FIGS. 12 and 13,
and like elements have been labeled accordingly. Furthermore, all
embodiments may be configured in parallel (i.e., in multiple-unit
configurations for scaling up) as set forth above.
[0081] FIG. 14 illustrates a four-stroke embodiment of the
invention comprising a single piston, four-stroke, integrated gas
springs engine 1400. The main physical difference between the
four-stroke engine 1400 of FIG. 14 and the two-stroke engine 1000
of FIG. 12 involves the location of the ports. In particular, in
the four-stroke engine 1400, the exhaust, injector, and intake
ports 370 are located at and/or near the bottom of the cylinder 105
adjacent to the impact plate 230.
[0082] FIG. 15 illustrates the four-stroke piston cycle 1500 for
the single piston integrated gas springs engine 1400 of FIG. 14. A
four-stroke piston cycle is characterized as having a power
(expansion) stroke, an exhaust stroke, an intake stroke, and a
compression stroke. A power stroke begins following combustion,
which occurs at the optimal volume, and continues until the
velocity of the piston 125 is zero, which marks the power-stroke
BDC position for that cycle.
[0083] During a power stroke, a portion of the kinetic energy of
the piston assembly 120 is converted into electrical energy by the
LEM 200, and another portion of the kinetic energy does compression
work on the gas in the driver section 160. When at and near the
power-stroke BDC, and if the driver section is to provide at least
some of the compression work, the pressure of the gas in the driver
section 160 is greater than the pressure of the gas in the
combustion section 130, which forces the piston 125 inwards toward
the midpoint of the cylinder 105. In the illustrated embodiment,
the gas in the driver section 160 can be used to provide at least
some of the energy required to perform an exhaust stroke. In some
cases, the LEM 200 may also provide some of the energy required to
perform an exhaust stroke. Exhaust ports 370 open at some point at
or near the power-stroke BDC, which can be before or after an
exhaust stroke begins. An exhaust stroke continues until the
velocity of the piston 125 is zero, which marks the exhaust-stroke
TDC position for that cycle. Exhaust ports 370 close at some point
before the piston 125 reaches its exhaust-stroke TDC position.
Therefore, at least some combustion products remain in the
combustion section 130. This process is referred to as residual gas
trapping.
[0084] With further reference to FIG. 15, at and near the
exhaust-stroke TDC, the pressure of the combustion section 130 is
greater than the pressure of the driver section 160, which forces
the piston 125 upwards. The trapped residual gas acts a gas spring
to provide at least some of the energy required to perform an
intake stroke. The LEM 200 may also provide some of the energy
required to perform an intake stroke. Intake ports 370 open at some
point during the intake stroke after the pressure within the
combustion section 130 is below the pressure of the intake gas. An
intake stroke continues until the velocity of the piston 125 is
zero, which marks the intake-stroke BDC position for that cycle.
The intake-stroke BDC position for a given cycle does not
necessarily have to be the same as the power-stroke BDC position.
Intake ports 370 close at some point at or near intake-stroke BDC.
A compression stroke continues until combustion occurs, which is at
a time when the velocity of the piston 125 is at or near zero. The
position of the piston 125 at which its velocity equals zero marks
its compression-stroke TDC position for that cycle. At and near the
compression-stroke TDC, the pressure of the gas in the driver
section 160 is greater than the pressure of the gas in the
combustion section 130, which forces the piston 125 downwards. The
gas in the driver section 160 is used to provide at least some of
the energy required to perform a compression stroke. The LEM 200
may also provide some of the energy required to perform a
compression stroke.
[0085] FIG. 15 shows one strategy for exchanging driver gas in
which the removal of driver gas occurs at some point during the
expansion stroke and the intake of make-up driver gas occurs at
some point during the compression stroke. As in the two-stroke
embodiment, the removal and intake of driver gas could also occur
in the reverse order of strokes or during the same stroke. However,
since the four-stroke embodiment has a separate exhaust stroke,
which requires less energy to perform than a compression stroke,
regulating the amount of air in the driver section 160 may require
a different approach, depending on how much the LEM 200 is used to
provide and extract energy during the four strokes.
[0086] FIG. 16 illustrates a second single piston, two-stroke,
fully gas springs and integrated linear electromagnetic machine
embodiment of an internal combustion engine 1600. Engine 1600
comprises a cylinder 105, piston assembly 520, and a combustion
section 130. In the illustrated configuration, piston assembly 520
comprises two pistons 525, piston seals 535, and a piston rod 545.
Unlike previous embodiments, the piston assembly 120 and translator
620 are completely located within the cylinder, and the LEM 600
(including stator 610) is disposed around the outside perimeter of
the cylinder 105. The piston assembly 520 is free to move linearly
within the cylinder 105. The cylinder 105 further includes
exhaust/injector ports 170, intake ports 180, driver gas removal
ports 185, and driver gas make-up ports 190. With further reference
to FIG. 16, this embodiment can operate using a two- or four-stroke
piston cycle using the same methodology set forth above.
[0087] FIG. 17 illustrates a third two-piston, two-stroke,
single-combustion section, separated gas springs embodiment of an
internal combustion engine 1700. Similar to engine 1000, engine
1700 comprises a main cylinder 105, piston assembly 120, and a
combustion section 130. However, the illustrated engine 1700 has
certain physical differences when compared with engine 1000.
Specifically, engine 1700 includes outer cylinders 705 that contain
additional piston 125, and the LEM 200 is disposed between the main
cylinder 105 and the outer cylinder 705. Outer cylinder 705
includes a driver section 710 located between the piston 125 and
the distal end of the cylinder 705 and a driver back section 720
disposed between the piston 135 and the proximal end of cylinder
705. Additionally, cylinder 105 includes a combustion back section
730 disposed between the piston 135 and the distal end of the
cylinder 105. The driver back section 720 and combustion back
section 730 are maintained at or near atmospheric pressure. As
such, the driver back section 720 is not scaled (i.e., linear
bearing 740 is provided with no gas seal), whereas the combustion
back section 730 is sealed (i.e., via seal 150), but has ports for
removal of blow-by gas (i.e., blow-by removal port 750) and for
make-up gas (i.e., make-up air port 760). In the illustrated
configuration, piston assembly 120 comprises two pistons 125,
piston seals 135, and a piston rod 145. The piston assembly 120 is
free to move linearly between the main cylinder 105 and the outer
cylinder 705. The piston rod 145 moves along bearings and is sealed
by gas seals 150 that are fixed to the main cylinder 105. The
cylinder 105 further includes exhaust/injector ports 170 and intake
ports 180. However, the driver gas removal ports 185 and driver gas
make-up ports 190 are located on outer cylinder 705 that contains
one of the two pistons 125 of the piston assembly 120. This
embodiment can operate using a two- or four-stroke piston cycle
using the same methodology set forth above.
[0088] The embodiments disclosed above comprise single-piston and
two-piston configurations, including: (i) an integrated gas spring
with a separated linear electromagnetic machine (FIGS. 6-9 and
12-15), (ii) a fully integrated gas spring and linear
electromagnetic machine (FIGS. 10 and 16), and (iii) a separated
gas spring and linear electromagnetic machine (FIGS. 11 and 17).
FIGS. 18-20 illustrate further embodiments of the invention
featuring integrated internal gas springs in which the gas spring
is integrated inside of the piston and the linear electromagnetic
(LEM) is separated from the combustor cylinder. Table 1 summarizes
the key distinctions between the four architectures described
herein including.
TABLE-US-00001 TABLE 1 Summary of the key distinctions between the
four architectures. Length of a Single-Piston Engine (Combustion
Section + Driver Architecture Section + LEM) Blow-by Location
Integrated Gas Spring, ~2x the stroke Into gas spring Separated LEM
Fully Integrated Gas Slightly larger than the Into gas spring
Spring and LEM stroke Separated Gas Spring ~3x the stroke Not into
gas spring and LEM Integrated Internal ~2x the stroke Not into gas
spring Gas Spring, Separate LEM
[0089] Integrated Internal Gas Spring
[0090] As illustrated in FIGS. 18-20 and summarized in Table 1, the
integrated internal gas spring (IIGS) architecture is similar in
length to the integrated gas spring with separated LEM architecture
illustrated in FIGS. 6-9 and 12-15. However, the IIGS architecture
eliminates the issues with respect to the blow-by gases from the
combustion section entering the gas spring, which also occurs in
the fully integrated gas spring and LEM architecture.
[0091] FIG. 18 is a cross-sectional view illustrating a
single-piston, two-stroke version of the IIGS architecture in
accordance with an embodiment of the invention. Many components
such as the combustion section 130 are similar to the components in
previous embodiments (e.g., FIG. 12), and are labeled accordingly.
The engine 1800 comprises a vertically disposed cylinder 105 with
piston assembly 1820 dimensioned to move within the cylinder 105 in
response to reactions within combustion section 130 near the bottom
end of the cylinder 105. An impact plate may be provided at the
bottom end of the vertically disposed cylinder to provide stability
and impact resistance during combustion. Piston assembly 1820
comprises a piston 1830, piston seals 1835, and a spring rod 1845.
The piston assembly 1820 is free to move linearly within the
cylinder 105. The piston rod 1845 moves along bearings and is
sealed by gas seals 150 that are fixed to the cylinder 105. In the
illustrated embodiment, the gas seals 150 are piston rod seals. The
cylinder 105 includes exhaust/injector ports 1870, 1880 for intake
of air, fuel, exhaust gases, air/fuel mixtures, and/or air/exhaust
gases/fuel mixtures, exhaust of combustion products, and/or
injectors. Some embodiments do not require all of the ports
depicted in FIG. 18. The number and types of ports depends on the
engine configuration, injection strategy, and piston cycle (e.g.,
two- or four-stroke piston cycles).
[0092] In the illustrated embodiment, the engine 1800 further
comprises an LEM 1850 (including stator 210 and magnets 1825) for
directly converting the kinetic energy of the piston assembly 1820
into electrical energy. LEM 1850 is also capable of directly
converting electrical energy into kinetic energy of the piston
assembly 1820 for providing compression work during a compression
stroke. The LEM 1850 can be a permanent magnet machine, an
induction machine, a switched reluctance machine, or some
combination of the three. The stator 210 can include magnets,
coils, iron, or some combination thereof. Since the LEM 1850
directly transforms the kinetic energy of the pistons to and from
electrical energy (i.e., there are no mechanical linkages), the
mechanical and frictional losses are minimal compared to
conventional engine-generator configurations.
[0093] With further reference to FIG. 18, the piston 1830 comprises
a solid front section (combustor side) and a hollow back section
(gas spring side). The area inside of the hollow section of the
piston 1830, between the front face of the piston and spring rod
1845, comprises a gas that serves as the gas spring 160, which
provides at least some of the work required to perform a
compression stroke. The piston 1830 moves linearly within the
combustor section 130 and the stator 210 of the LEM 1850. The
piston's motion is guided by bearings 1860, 1865, which may be
solid bearings, hydraulic bearings, and/or air bearings. In the
illustrated embodiment, the engine 1800 includes both external
bearings 1860 and internal bearings 1865. In particular, the
external bearings 1860 are located between the combustion section
130 and the LEM 1850, and the internal bearings 1865 are located on
the inside of the hollow section of the piston 1830. The external
bearings 1860 are externally fixed and do not move with the piston
1830. The internal bearings 1865 are fixed to the piston 1830 and
move with the piston 1830 against the spring rod 1845.
[0094] With continued reference to FIG. 18, the spring rod 1845
serves as one face for the gas spring 160 and is externally fixed.
The spring rod 1845 has at least one seal 1885 located at or near
its end, which serves the purpose of keeping gas within the gas
spring section 160. Magnets 1825 are attached to the back of the
piston 1830 and move linearly with the piston 1830 within the
stator 210 of the LEM 1850. The piston 1830 has seals 1835 to keep
gases in the respective sections. The illustrated embodiment
includes (i) front seals that are fixed to the piston 1830 at or
near its front end to keep to gases from being transferred from the
combustion section 130, and (ii) back seals that are fixed to the
cylinder 105 and keep intake gases and/or blow-by gases from being
transferred to the surroundings.
[0095] FIG. 19 is a cross-sectional view illustrating an embodiment
1900 of a gas spring rod 1845 in accordance with the principles of
the invention. Specifically, the spring rod 1845 includes a central
lumen 1910 that allows mass to be transferred between the gas
spring section 160 to a reservoir section 1920 that is in
communication with the surroundings. The communication with the
surroundings is controlled through a valve 1930. The amount of mass
in the gas spring 1845 is regulated to control the pressure within
the gas spring 1845 such that sufficient compression work is
available for the next piston cycle.
[0096] FIG. 20 is a cross-sectional view illustrating a two-piston,
two-stroke version of the IIGS engine 2000 in accordance with an
embodiment of the invention. Most of the elements of the two-piston
embodiment are similar to those of the single-piston embodiment of
FIG. 18, and like elements are labeled accordingly. In addition,
the operating characteristics of the single- and two-piston
embodiments are similar as described in previous embodiments,
including all the aspects of the linear alternator, breathing,
combustion strategies, etc.
[0097] While various embodiments of the present invention have been
described above, it should be understood that they have been
presented by way of example only, and not of limitation. Likewise,
the various diagrams may depict an example architectural or other
configuration for the invention, which is done to aid in
understanding the features and functionality that can be included
in the invention. The invention is not restricted to the
illustrated example architectures or configurations, but the
desired features can be implemented using a variety of alternative
architectures and configurations. Indeed, it will be apparent to
one of skill in the art how alternative functional, logical or
physical partitioning and configurations can be implemented to
implement the desired features of the present invention. Also, a
multitude of different constituent module names other than those
depicted herein can be applied to the various partitions.
Additionally, with regard to flow diagrams, operational
descriptions and method claims, the order in which the steps are
presented herein shall not mandate that various embodiments be
implemented to perform the recited functionality in the same order
unless the context dictates otherwise.
[0098] Although the invention is described above in terms of
various exemplary embodiments and implementations, it should be
understood that the various features, aspects and functionality
described in one or more of the individual embodiments are not
limited in their applicability to the particular embodiment with
which they are described, but instead can be applied, alone or in
various combinations, to one or more of the other embodiments of
the invention, whether or not such embodiments are described and
whether or not such features are presented as being a part of a
described embodiment. Thus, the breadth and scope of the present
invention should not be limited by any of the above-described
exemplary embodiments.
[0099] Terms and phrases used in this document, and variations
thereof, unless otherwise expressly stated, should be construed as
open ended as opposed to limiting. As examples of the foregoing:
the term "including" should be read as meaning "including, without
limitation" or the like; the term "example" is used to provide
exemplary instances of the item in discussion, not an exhaustive or
limiting list thereof, the terms "a" or "an" should be read as
meaning "at least one," "one or more" or the like; and adjectives
such as "conventional," "traditional," "normal," "standard."
"known" and terms of similar meaning should not be construed as
limiting the item described to a given time period or to an item
available as of a given time, but instead should be read to
encompass conventional, traditional, normal, or standard
technologies that may be available or known now or at any time in
the future. Likewise, where this document refers to technologies
that would be apparent or known to one of ordinary skill in the
art, such technologies encompass those apparent or known to the
skilled artisan now or at any time in the future.
[0100] The presence of broadening words and phrases such as "one or
more," "at least," "but not limited to" or other like phrases in
some instances shall not be read to mean that the narrower case is
intended or required in instances where such broadening phrases may
be absent. The use of the term "module" does not imply that the
components or functionality described or claimed as part of the
module are all configured in a common package. Indeed, any or all
of the various components of a module, whether control logic or
other components, can be combined in a single package or separately
maintained and can further be distributed in multiple groupings or
packages or across multiple locations.
[0101] Additionally, the various embodiments set forth herein are
described in terms of exemplary block diagrams, flow charts and
other illustrations. As will become apparent to one of ordinary
skill in the art after reading this document, the illustrated
embodiments and their various alternatives can be implemented
without confinement to the illustrated examples. For example, block
diagrams and their accompanying description should not be construed
as mandating a particular architecture or configuration.
* * * * *
References