Note: Descriptions are shown in the official language in which they were submitted.
CA 02901049 2015-08-19
NON-PROVISIONAL PATENT APPLICATION
TITLE: LINEAR ACTUATION FOR CONTINUOUSLY VARIABLE-
STROKE CYCLE ENGINE
INVENTORS: Miin Jeng YAN
Hailuat D. YAN
CROSS-REFERENCE TO RELATED APPLICATIONS
This continuation-in-part application claims benefit under 35 U.S.C. 120 from
U.S.
Patent Application No. 13/900,395 filed on May 22, 2013, which claims priority
under 35 U.S.C.
119(e) from U.S. Provisional Patent Application No. 61/649,933 filed on May
22, 2012, all of
which is incorporated herein by reference in its entirety.
FIELD
Embodiments disclosed herein relate to internal combustion engines, and in
particular,
piston internal combustion engines. More particularly, embodiments disclosed
herein relate to
an actuator and assembly for variable-stroke cycle internal combustion
engines.
BACKGROUND AND SUMMARY
The internal combustion engine is an engine where the combustion of a fuel
occurs with
an oxidizer in a combustion chamber that is an integral part of the working
fluid flow circuit. In
an internal combustion engine the expansion of the high-temperature and high-
pressure gases
produced by combustion apply direct force to some component of the engine,
typically a piston.
This force moves the component over a distance, transforming chemical energy
into useful
mechanical energy.
In one aspect, embodiments disclosed herein relate to a variable-stroke
reciprocating
internal combustion engine, the engine having an engine shaft and a piston
configured to
reciprocate within a cylinder chamber having an axis, each piston having a
first piston part
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operable to move in unison with or separately from a second piston part to
define piston strokes
for different thermal functions of the engine, the engine including an
assembly pivotally coupled
to the first piston part at a copy point and an actuator coupled to the
assembly, wherein the
actuator is operable to control motion of the assembly to thereby define
substantially linear
movement of the copy point along the cylinder chamber axis.
In other aspects, embodiments disclosed herein relate to a method of operating
a variable-
stroke reciprocating internal combustion engine, the engine having an engine
shaft and a piston
configured to reciprocate within a cylinder chamber having an axis, each
piston having a first
piston part operable to move in unison with and separately from a second
piston part to define
piston strokes for different functions of the engine, the method including
providing an assembly
pivotally coupled to the first piston part at a copy point, and an actuator
coupled to the assembly
and operating the actuator to control motion of the assembly and thereby
define substantially
linear movement of the copy point along the cylinder chamber axis.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is illustrated in the accompanying drawings wherein,
Figure 1 illustrates a schematic view of an embodiment of a piston-train guide
assembly.
Figure 2 illustrates a cross-section view normal to the axis of rotation of
the crankshaft of
an embodiment of an engine having the piston-train guide assembly of Figure 1.
Figure 3 illustrates an embodiment of a curved-guide linear actuator
mechanism.
Figures 4 and 5 illustrate an embodiment of a pantographic-guide linear
actuator
mechanism.
DETAILED DESCRIPTION
The aspects, features, and advantages of one or more embodiments mentioned
herein are
described in more detail by reference to the drawings, wherein like reference
numerals represent
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like elements. Embodiments disclosed herein provide an assembly and guide, or
guided
assembly, incorporated within a piston-train of a differential or variable
stroke internal
combustion engine, which may be incorporated separately or in a single
apparatus. In certain
embodiments, the assembly may be referred to as a robotic arm assembly. In
other
embodiments, the assembly may be referred to as an actuator assembly. The
robotic assembly
may be attached to an engine block or other location at one end with an arm-
like lever apparatus
extended toward the cylinder axis to move the piston stem of a piston part
(e.g., a first or inner
piston part) in a substantially linear lengthwise motion along the cylinder
axis.
It may be beneficial when the combinations of the four engine strokes, in
displacements
and periods, are continuously optimized real-time during engine operations for
fuel efficiency,
power, and emission. For such purposes, a robotic optimization device,
controlled by an engine's
electronic control unit, having a robotic arm extending into the cylinder axis
acting directly on
the piston stem may be utilized. The robotic arm device may be coupled to the
piston stem to
operate the first piston part. The robotic device may be located away from the
cylinder chamber
and from the moving parts of the piston kit. The robotic arm device may be
configured to
perform multi-dimensional motions to maintain a linear lengthwise motion of
the piston stem
and first piston part along the cylinder axis. In certain embodiments, a
linear robotic device, or a
linear actuator apparatus, acting on the piston lever is provided to maintain
a linear lengthwise
motion of the piston stem and first piston part along the cylinder axis.
Referring to Figure 1, a schematic view of a piston-train guide assembly in
accordance
with one or more embodiments of the present disclosure is shown. The piston-
train guide
apparatus 100 (or assembly) may be incorporated within the piston-train in the
differential stroke
internal combustion engine illustrated in Figure 2. As used herein, a "piston-
train" may include
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a piston, piston lever-link-bar and guide assembly coupled together as an
assembly and operable
within the engine. The guide assembly may also be referred to herein as a
control and guide
apparatus or a control and linkage assembly.
The differential stroke internal combustion engine typically includes an
engine block 210
having one or more cylinder bores 212, and an inner or first piston part 220
located within each
of the one or more cylinder bores 212. The inner piston part 220 may be in
sliding contact (or
abutting) engagement with a respective cylinder bore wall 213. A piston stem
230 is coupled at
a first end 232 to the inner piston part 220, and is hingedly (or pivotally)
coupled at a second end
234 to a piston lever-link-bar 110. The hinged coupling (pivotal junction) may
define a 'copy'
point 102, described in greater detail below.
The guide apparatus 100 defines and includes a linkage assembly (e.g., a four-
bar-
linkage) including a portion 111 of the piston lever-link-bar 110, a fulcrum-
link bar 112, a force-
link bar 114, and a rocker-link bar 118. In defining and locating the four-bar-
linkage, the guide
apparatus 100 may be hingedly coupled to the engine block 210 at a first hinge
junction 120 of a
first end of the fulcrum-link bar 112 and a first end of the rocker-link bar
118. The hinged
coupling (pivotal junction) defines an 'anchor' (or attachment) point 104,
described in greater
detail below. The four-bar-linkage further includes a second hinge junction
122 of a second end
of the fulcrum-link bar 112 and a first end of the portion 111 of the piston
lever-link-bar 110, a
third hinge junction 124 of a second end of the rocker-link bar 118 and a
first end of the force-
link bar 114, and a fourth hinge junction 126 of a second end of the force-
link bar 114 and a
second end of the portion 111 of the piston lever-link-bar 110.
A guide element or guide roller 130 is coupled (for example rotatably or
pivotally) to the
force-link bar 114 at an 'origin' point (or axis) 106. The 'origin' point 106
is located at the
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intersection between the force-link bar 114 and an imaginary line¨indicated by
line 108¨
defined between the 'copy' point 102 and the 'anchor' point 104. The guide
roller 130 may be in
sliding or rolling contact with a guide apparatus 240. In certain embodiments,
the guide
apparatus 240 may be integrally formed as a structure within and defined by
the engine block
210. For example, the guide apparatus may be formed as a channel, groove, or
other structure
within the engine. In other embodiments, the guide apparatus 240 may be
rigidly attached or
fastened to the engine block 210. As shown, in certain embodiments, the guide
apparatus 240
may be linear or substantially linear. The guide roller 130 moves within the
guide apparatus 240
such that the guide roller 130 and 'origin' point 106 move along a guide axis
150 of the guide
apparatus 240 that is parallel to the cylinder axis 250 of cylinder 212. In
certain embodiments,
the guide element may include a spring element (not shown) of any type coupled
to the linkage
assembly to centrally bias and control the copy point substantially along the
cylinder chamber
axis.
The four-bar-linkage of the guide apparatus 100 may be configured to form a
pantographic assembly or apparatus. It will be understood by those skilled in
the art that a
pantographic assembly may be formed from mechanical linkages connected in a
manner based
on parallelograms, such that movement of one point of the assembly (for
example, the 'origin'
point 106) produces respective (and possibly scaled) movements in a second
point of the
assembly (for example, the 'copy' point 102).
In certain embodiments, the scaled movement of the 'copy' point 102 is
restrained along
the cylinder axis 250 by the movement of the 'origin' point 106 along the
guide axis 150. This
pantographic assembly of the four-bar-linkage, which effectively translates
motion in a
controlled fashion, is used as a motion guide for the 'copy' point 102.
Accordingly, in certain
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embodiments, the four-bar-linkage defines a pantographic device that guides
the piston lever-
link-bar 110 to move at the pivotal junction with the piston stem 230 (i.e.,
the *copy' point 102)
in a straight line motion lengthwise along the cylinder axis 250. In other
words, as the origin
point 106 travels along guide axis 150 of the linear guide 240, the copy point
102 travels in a
lengthwise linear motion along cylinder axis 250 of the cylinder 212.
It will be appreciated that other guide elements or devices may also be
incorporated with
the four-bar-linkage of the guide apparatus 100 at locations that have a
functional relationship
with the linear motion of the copy point 102. As one example, a guide element
or guide roller
may be located on the piston lever-link-bar 110 at the junction 126 with the
force-link bar 114.
In this example, a curved or non-linear guide channel may guide lateral motion
of the piston
lever-link-bar 110, such that the pivotal junction 102 between the piston
lever-link-bar 110 and
the piston stem 230 makes linear lengthwise motions aligned with the cylinder
axis 250 as the
piston lever-link-bar 110 is oscillated to actuate and stroke the inner piston
part 220.
In certain embodiments, a functional relationship exists between a particular
location on
the linkage assembly and the copy point 102. For example, the functional
relationship may
comprise moving a particular location on the linkage assembly, and
consequently moving the
copy point 102 accordingly. Further still, the functional relationship may
comprise moving a
particular location on the linkage assembly, in either a linear or non-linear
fashion, and
consequently moving the copy point 102 in a linear fashion. In certain
embodiments, the
particular location on the linkage assembly may comprise the origin point 106.
Accordingly, the
guide element or guide roller 130 may be incorporated with the four-bar-
linkage at certain
locations to provide linear motion to the copy point 102, as will be
understood by those skilled in
the art.
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In certain embodiments, a spring device (not shown) located or attached at any
location
on the piston-train may be included. For example, the spring device may be
proximal to the
hinge junction 122 (of a second end of the fulcrum-link bar 112 and a first
end of the portion 111
of the piston lever-link-bar 110) may restrict or guide lateral movement of
the piston lever-link-
bar 110. Lateral movement is defined as movement not substantially aligned
with the cylinder
axis 250. The spring may be any type of spring device as will be understood by
one of ordinary
skill in the art. Further, the spring may be anchored at one end to the engine
block and the other
end to the piston-train. Alternatively, the spring may be anchored to only the
engine block. The
spring may be biased to restrict or reduce lateral movement of the fulcrum-
link bar 112 such that
the piston stem 230 stays within a tolerance limit substantially aligned with
the cylinder axis 250.
Referring to Figure 2, a cross-section view normal to the axis of rotation of
the crankshaft
of a differential stroke engine having a control and guide apparatus 100
incorporated therein in
accordance with one or more embodiments of the present disclosure is shown. A
differential
stroke piston moves within the fixed cylinder 212 between a fixed cylinder
head 16 above and a
rotating crankshaft 18 below, referring to the orientation of the engine shown
in Figure 2.
Charging and exhausting cylinder 212 is controlled by intake valve 17a and
exhaust valve 17b
respectively. Combustion is initiated by a spark plug 20 (not used in diesel
applications) in
cylinder head 16. Engine 210 is operable to complete one full combustion cycle
per engine
revolution.
The differential stroke piston has an inner piston part 220 which closes and
seals the
combustion chamber and an outer piston part 231 which is connected by a
connecting rod 22 to
the crankshaft 18 and also serves as a carrier for the inner piston part 220
during portions of its
cycle. Embodiments disclosed herein provide for the inner piston part 220 to
operate on four
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strokes per cycle and the outer piston part 231 to operate on two strokes per
cycle. During the
exhaust and the intake portions of the cycle, the inner piston part 220 and
outer piston part 231
separate. During separation, inner piston part 220 is actuated and driven by
the control and guide
apparatus 100 described in Figure 1. As shown, in certain embodiments, the
guide apparatus 100
may be located outside of the cylinder and cylinder bore 212 and positioned
away from the
movements of the piston parts and engine shaft. Meanwhile, the outer piston
part 231 continues
to move under control of crank arm 24 and connecting rod 22.
In certain embodiments, an actuator (e.g., a robotic arm device) operable
independent of
the engine shaft (e.g., crankshaft) may be provided to define or optimize the
piston strokes
during different thermal functions of the engine and adapt the optimal piston
stroke combinations
to changing loading conditions during engine operations. The actuator may be
synchronized
with other engine components, such as an associated electronic or mechanical
cam-less valve
train, e.g., a valve train system that has no cams and is operated by
electronics. The actuator and
other engine components may be controlled and optimized by an engine
electronic control unit.
In other embodiments, the actuator may be a linear actuator. In certain
embodiments, the
actuator may comprise an electromechanical actuator, or any device which
carries out electrical
operations by using moving parts, or actuator tongue that moves in a
substantially linear
direction. The electromechanical actuator may be controlled by an engine
electronic control
unit. In other embodiments, the actuator may be controlled by hydraulic,
mechanical, or
electromechanical systems or components.
In one embodiment, a guide element on the piston lever is provided that
travels within a
curved guide and guides the lever motion at the piston stem junction to be
linear along the
cylinder axis as the lever swings about a fulcrum. In another embodiment, a
linear robotic device
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is provided that acts on the lever using the pantographic principle. The
motion of the piston
lever or robotic arm at the piston stem junction is linear lengthwise along
the cylinder axis, while
motion away from the cylinder axis is two dimensional both parallel and
perpendicular to the
cylinder axis.
Figure 3 illustrates an embodiment of a curve-guided linear actuator
mechanism. Two-
part piston having a first piston part 220 and second piston part 222 is
shown. A linkage
assembly defines a three-bar-linkage including a piston lever-link-bar 111, a
fulcrum-link bar
112, and a force-link bar 114. Three-bar-linkage is defined and located by a
first hinge junction
120 (e.g., an anchor point) pivotally coupled to the engine block 210 and
connecting a first end
of the fulcrum-link bar 112, a second hinge junction 122 connecting a second
end of the fulcrum-
link bar 112 and a first end of the piston lever-link-bar 111, a third hinge
junction 124 connecting
a linear actuator 240 and a first end of the force-link bar 114, and a fourth
hinge junction 126
connecting a second end of the force-link bar 114 and a location on the piston
lever-link-bar 111.
A linear actuator tongue 240 (housed in the actuator apparatus 242) may be
pivotally attached to
the force link bar 114 via pin 124. A guide element 130 is disposed within a
curved guide device
340 formed integrally with or fastened to the engine block 210. The guide
element 130 may be
coupled at pin 126.
As the first piston part 220 makes the linear lengthwise motion in the
cylinder 212, the
fulcrum-link bar 112 swings in an arc around the pivot attachment 120 on the
engine block 210
toward and away from the cylinder axis 250. The force-link bar 114 and guide
element 130 move
in multiple dimensions (e.g., curved) to compensate for the piston lever
motion. In this fashion,
the linear actuator tongue 240 may control the motion of the lever 110 to
define substantially
linear movement of the copy point 102 along the cylinder axis 250. A
relationship between
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curved motion of the guide element 130 and linear motion of the copy point 102
may be
correlated and calculated with a computer or engine electronic control unit.
The axis of the
linear actuator need not be parallel to the cylinder axis 250.
Figures 4 and 5 illustrate an embodiment of a linear relationship implemented
via a
pantographic guided linear actuator mechanism. The pantograph includes a 4-bar-
linkage of
linkage bars 111, 112, 114, and 118 with a lever bar which consist of one of
the linkage bar 111
and its extension 110. The force-linkage-bar 114 may have two sections divided
by its junction
with the linear actuator at 106. The applied force between the joint 106 and
126 may be greater
than that between 106 and 124. The more lightly loaded section 106 to 124 may
be built into a
linear actuator tongue 240. The linkage-bar 118 may be equally light-loaded,
and configured to
provide a guiding function, and may be made similarly thinner to fit into the
actuator tongue. The
linear actuator tongue 240 may be attached to the force-linkage bar at the
origin point 106 of the
pantograph. The functional relationship between linear motions of the robotic
actuator and the
desired motions of the inner piston 220 strokes may be determined by
multiplying by a constant.
The axis of linear actuator tongue 240 may be parallel to that of the cylinder
axis 250.
In certain embodiments, a variable-stroke reciprocating internal combustion
engine, the
engine having an engine shaft and a piston configured to reciprocate within a
cylinder chamber
having an axis, each piston having a first piston part operable to move in
unison with or
separately from a second piston part to define piston strokes for different
thermal functions of the
engine, includes an assembly pivotally coupled to the first piston part at a
copy point and an
actuator coupled to the assembly. The actuator is operable to control motion
of the assembly to
thereby define substantially linear movement of the copy point along the
cylinder chamber axis.
The assembly may be coupled to the engine at an anchor point. The actuator may
comprise a
CA 02901049 2015-08-19
linear actuator. The assembly comprises a four-bar-linkage including a piston
lever-link-bar, a
fulcrum-link bar, a force-link bar, and a rocker-link bar. The four-bar-
linkage is defined and
located by a first hinge junction pivotally coupled to the engine and
connecting a first end of the
fulcrum-link bar and a first end of the rocker-link bar, a second hinge
junction connecting a
second end of the fulcrum-link bar and a first end of the piston lever-link-
bar, a third hinge
junction connecting a second end of the rocker-link bar and a first end of the
force-link bar, and a
fourth hinge junction connecting a second end of the force-link bar and a
location on the piston
lever-link-bar. The four-bar linkage defines a parallelogram forming a
pantograph, and the
coupling between the actuator and linkage is located along a line defined
between the copy point
and the anchor point.
Or, the assembly defines a three-bar-linkage including a piston lever-link-
bar, a fulcrum-
link bar, and a force-link bar. The three-bar-linkage is defined and located
by a first hinge
junction pivotally coupled to the engine and connecting a first end of the
fulcrum-link bar, a
second hinge junction connecting a second end of the fulcrum-link bar and a
first end of the
piston lever-link-bar, a third hinge junction connecting the linear actuator
and a first end of the
force-link bar, and a fourth hinge junction connecting a second end of the
force-link bar and a
location on the piston lever-link-bar. A guide element is movable within a
curved guide defined
within the engine and coupled with the three-bar linkage, wherein the guide
element moves in an
arc as the first piston part makes a linear lengthwise motion in the cylinder.
The actuator
comprises an electromechanical actuator operable independently of the engine
shaft. An
electronic engine control unit is used for operating the electromechanical
actuator.
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A method of operating a variable-stroke reciprocating internal combustion
engine, the
engine having an engine shaft and a piston configured to reciprocate within a
cylinder chamber
having an axis, each piston having a first piston part operable to move in
unison with or
separately from a second piston part to define piston strokes for different
thermal functions of the
engine, includes providing an assembly pivotally coupled to the first piston
part at a copy point,
and an actuator coupled to the assembly and operating the actuator to control
motion of the
assembly and thereby define substantially linear movement of the copy point
along the cylinder
chamber axis. The method further comprises operating an electromechanical
actuator. The
method further comprises operating the actuator by an electronic engine
control unit. The
method further comprises operating the actuator in a substantially linear
direction. The method
further comprises operating the assembly independently of the engine shaft.
The method further comprises providing a guide element movable within a curved
guide
defined within the engine and coupled with the assembly at a first location
having a functional
relationship with the copy point. The method further comprises moving the
guide element in
multiple dimensions within the curved guide and accordingly, moving the first
piston part within
the cylinder substantially along the cylinder axis. The method further
comprises defining a
pantograph apparatus in the assembly, wherein the pantograph apparatus defines
a one-to-one
scaled relationship between an origin point and the copy point, activating the
linear actuator and
moving the origin point a first linear distance, and moving the copy point a
second linear
distance, wherein the second linear distance is a scaled amount relative to
the first linear
distance. The method further comprises operating the pantograph apparatus
comprising a four-
bar-linkage including a piston lever-link-bar, a fulcrum-link bar, a force-
link bar, and a rocker-
link bar.
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Advantageously, embodiments disclosed herein provide a control and guide
apparatus in
which motion of the inner piston portion is guided at the chamber inner end by
the piston crown
sliding along the cylinder wall and at the piston stem outer end by the guide
apparatus to move
substantially along the cylinder axis. Because of the guide apparatus, and
particularly the guide
element movable within and along an axis of a guide channel, the inner piston
part may move up
and down with substantially no lateral movement of the piston stem and
substantially little lateral
thrust against the piston stem from the piston lever-link-bar. Accordingly,
stresses and wear of
the inner piston portion and on the cylinder wall induced by the piston
sideways motions may be
reduced. The guide apparatus may also reduce the sliding friction and
'slapping' of the inner
piston portion against the cylinder wall.
Moreover, the four-bar-linkage assembly requires relatively little space (as
shown in
Figure 2) within the engine itself. Still further, the four-bar-linkage,
acting as a pantographic
assembly, is capable of moving the piston stem and inner piston part an amount
much larger than
the amount required to move the guide element within the guide channel.
Reference throughout this specification to "one embodiment" or "an embodiment"
or
"certain embodiments" means that a particular feature, structure or
characteristic described in
connection with the embodiment is included in at least one embodiment of the
present
disclosure. Therefore, appearances of the phrases "in one embodiment" or "in
an embodiment"
or "in certain embodiments" in various places throughout this specification
are not necessarily all
referring to the same embodiment, but may. Furthermore, the particular
features, structures or
characteristics may be combined in any suitable manner, as would be apparent
to one of ordinary
skill in the art from this disclosure, in one or more embodiments.
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In the claims below and the description herein, any one of the terms
comprising,
comprised of or which comprises is an open term that means including at least
the
elements/features that follow, but not excluding others. Therefore, the term
comprising, when
used in the claims, should not be interpreted as being limitative to the means
or elements or steps
listed thereafter. Any one of the terms including or which includes or that
includes as used
herein is also an open term that also means including at least the
elements/features that follow
the term, but not excluding others. Accordingly, including is synonymous with
and means
comprising.
It should be understood that the term "coupled," when used in the claims,
should not be
interpreted as being limitative to direct connections only. "Coupled" may mean
that two or more
elements are either in direct physical, or that two or more elements are not
in direct contact with
each other but yet still cooperate or interact with each other.
Although one or more embodiments of the present disclosure have been described
in
detail, it will be apparent to those skilled in the art that many embodiments
taking a variety of
specific forms and reflecting changes, substitutions and alterations may be
made without
departing from the spirit and scope of the invention. The described
embodiments illustrate the
scope of the claims but do not restrict the scope of the claims.
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