Note: Descriptions are shown in the official language in which they were submitted.
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In-line Rotary Piston Engine
The present invention relates to a device used to convert
chemical energy to mechanical energy. Such devices employ pistons
to compress a combustible mixture which after ignition expands,
thus pushing the pistons back. In the device disclosed here the
pistons rotate about a fixed axis to compress the mixture rather
than follow a translational motion. Although such devices are used
for a variety of purposes they are commonly referred to as rotary
piston type engines.
Various types of devices, collectively known as engines, have
been used to convert chemical energy to mechanical energy. And
their primary use has been in the auto industry - to drive cars.
Most of these engines achieve the conversion between the two forms
of energy by using pistons that follow a translational motion.
First, a combustible mixture is introduced into a chamber. Next,
the mixture is compressed by the piston, then it is ignited. The
resulting gases expand quickly and push the piston back. This,
with some minor variations is the principle on which most car
engines function. Such engines are known as four-stroke engines.
One of the disadvantages of such a cycle is the amount of energy
lost during the conversion process. Most of the energy is lost due
to the friction between the pistons and the walls of the chamber in
which they move. Also, the camshaft used to control the intake and
exhaust valves is turned using energy from the conversion. These
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and others added together result in a low conversion ratio. Thus,
only about 30% of the chemical energy of the combustible is
available as useful mechanic energy. To compound the problem there
are pollutants to be considered. Due to the construction and the
remaining burned gases in the ignition chamber from previous cycles
of such, engines the exhaust emissions contain considerable
emissions of carbon monoxide and nitrogen oxides. Although new
technologies are being developed to lower pollutant emissions, the
problem of pollutants from car engines is still considerable.
Two-stroke engines which are somewhat similar to the four-
stroke engines present the same problems, although the pollutant
emissions are lower than those of the four-stroke engines.
However, due to power considerations, the four-stroke engine is
preferred over the two-stroke one; improvisations to the latter
type of engine to make it competitive with the four-stroke engine
have resulted in needless complications of the engine.
Other devices used to convert chemical energy into mechanical
energy employ pistons which move in a circular motion. These
devices are also known as rotary piston engines. Examples of such
devices are described and illustrated in United States Patent No.
4,056,338 dated August 19, 1976, claiming priority, application
Germany, granted to Dankwart Eiermann, assignor to Wankel GmbH of
Germany, for a "Rotary Piston Engine," and in United States Patent
No. 4,056,339 dated October 15, 1976, claiming priority,application
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Japan, granted to Kunio Doi, Kozo Koike, and Toshiro Sasaki of
Japan, assignors to Toyo Kogyo Co., Ltd. of Japan for a "Rotary
Piston Type Internal Combustion Engines." Such devices comprise a
housing whose inner wall has a trochoidal configuration. A
triangular rotor with arcuate sides is disposed in the housing for
rotation with apex portions in sliding contact with the inner wall
of the housing. Thus, working chambers of variable volume are
defined, one working chamber being in the intake stroke, another
working chamber being in the exhaust stroke, while others are in
the ignition stroke. One of the disadvantages of such engines
results from their construction. The apex portions of the rotor
bear most of the force developed by the combustion resulting in a
high stress along the sealing line of the piston. Eventually, the
extreme pressure leads to premature wearing out of the apex areas.
Another problem of such engines is the low compression ratio,
compared to the engine size, leading to fuel economy problems.
Finally, the sealing arrangements required by such engines are
complex, increasing the cost of such an engine. Researchers in the
United States and other countries with well-developed auto
industries have tried to eliminate some of the disadvantages of
rotary engines but were not always successful. In the end, it was
concluded that rotary engines would not be a viable alternate to
present engines.
The present invention consists of at least two housings, four
shafts, each carrying a piston, the shafts being free to turn
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inside the two housings, sealing lines, and an output shaft. The
two housings are distinguished as the first and second housings.
The first housing comprises three parts. The middle part of the
first housing, also referred to as the frame in this description,
may have an outward rectangular shape, while the inner wall is
composed of a multitude of circular arcs, describing four
cylinders, which intersect along their lengths, the cylinders being
arranged in line. The outer two parts, referred to as end walls,
are also rectangular in shape and each end wall has a set of four
holes which accommodate and support the four shafts. One of the
end walls is flanged on the side opposite the frame. The flanged
end wall has a notch on the flanged side, in which one end of the
output shaft fits. The end walls fit on the middle part at right
angles. The second housing comprises the flanged wall of the first
housing and a rectangular cover which fits on the flanged side,
making right angles everywhere.
The first housing contains four shafts, which pass through the
its two end walls, and are parallel to the inner wall of the frame
of the first housing. The two inner shafts may be thicker than the
outer two. The two inner shafts carry the primary cylinders.
Hence, the inner shafts are termed primary shafts. The primary
cylinders are right circular paraboloids. In this disclosure,
right circular paraboloid describes a cylindrical object whose
faces are parabolas with the vertex and opposite extremity being
circular, the faces forming right angles with the sides. The
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primary cylinders are fastened to their shafts, and are free to
turn inside the first housing, the space occupied by the primary
cylinders being referred to as primary chambers. The distance from
the centre of the shaft to the vertex is given by the difference
between the distance between the primary chambers and the radius of
a primary chamber. The opposite end arc has a radius of curvature
slightly less than the radius of the primary chamber, so that
rotation in the housing is not hampered. The primary cylinders are
rotating such that the symmetry lines passing through the vertex,
and the centre of the shaft, cutting the opposite arc in half, are
always parallel and the two vertices always point in the same
direction. The two primary cylinders are in continuous contact
throughout the cycle. Each of the primary cylinders may also carry
a pair of circular, concentric seals on each face, and at least two
linear seals which are mounted along the side edges of the
cylinders. The circular seals, shaft, vertex and extremity
opposite vertex are all pieces of concentric circles. Each linear
seal is comprised of at least three parts: two U-shaped parts which
fit on each face and run radially outward from the outer circular
seal to the edge, and another bow-like part whose ends fit beneath
those of the U-shaped parts, and thus is prevented to escape, and
running the entire length of the side edge. All seals are pushed
tightly toward the wall of the housing by springs mounted
underneath them. The two outer shafts carry the secondary
cylinders. Hence, they are referred to as secondary shafts. The
secondary cylinders are right humped dees. In this disclosure
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right humped dee describes a cylindrical object whose faces are D-
shaped, with a D-shaped protrusion on the flat side of the "D," the
faces forming right angles with the sides everywhere. The
secondary cylinders are fastened to their shafts and are free to
turn inside the first housing. The space occupied by a secondary
cylinder is referred to as a secondary chamber. Each of the
primary cylinders is in continuous contact with one of the
secondary cylinders. The secondary cylinders rotate in opposite
directions relative to the primary cylinders. All cylinders rotate
at the same angular speed. In other words, all cylinders take the
same time to complete one full turn.
The secondary housing contains the ends of the four shafts
carrying the four cylinders. It also contains one end of the
output shaft, which fits in the notch of the flanged wall. The
output shaft is placed between the primary shafts. All shafts in
the second housing carry a gear. The gearing ratio between primary
and secondary shafts shall be 1:1, ensuring the same angular speed
for all cylinders; the gearing ratio between the primary shafts and
the output shaft may be 1:1. The output shaft extends outside the
second housing through 6 of the hole in the cover which fits on the
flanged wall.
In another aspect of the invention, the first housing provides
locations for sparkplugs. The locations for the sparkplugs are
provided along the lines of intersection of the primary chambers,
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in the area of the ignition chamber, located in the primary
intersection lines. There may be at least one sparkplug along each
primary intersection line. The intersection lines of the primary
chambers with the secondary chambers, the secondary intersection
lines, provide locations for the exhaust and intake ducts. Based
on the direction of rotation of the primary cylinders, clockwise in
this description, the intake ducts are placed on the intersection
between main chamber with auxiliary chamber. There may be an
intake duct along each such secondary intersection line. The
exhaust ducts are placed on the secondary intersection lines
directly to the left of the primary intersection lines. There may
be one exhaust duct on each such secondary intersection line.
Starting at one sparkplug and moving along the inner wall of the
first housing in the same direction as the primary cylinders, the
arrangement of the sparkplugs, intake and exhaust ducts is
sparkplug - exhaust duct - intake duct - sparkplug - exhaust duct -
intake duct - sparkplug. This order holds true for any direction
of rotation of the primary cylinders.
The invention, as exemplified by a preferred embodiment is
described with reference to the drawings in which:
Figure 1 is a cross section view of the first housing, showing
the positioning and shapes of the four cylinders, as well as
part of the seals on the primary cylinders;
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Figure 2 is a section (side view) taken along line 2-2 of
Figure 1, showing the end walls of the first housing, the
second housing, and one linear seal on a primary cylinder;
Figure 3 is an expanded view of a face of a primary cylinder
showing the seal lines;
Figure 4 is a section taken along line 3-3 of Figure 3 and
shows a complete seal line;
Figure 5 is a cross section of the first housing showing the
cylinders' positions at the beginning of the compression cycle
by rotary piston marked "lst";
Figure 6 shows the arrangement of Figure 5 advanced to the
ignition phase of the cycle of the cylinder marked "lst";
Figure 7 shows the arrangement of Figure 6 advanced to the
compression phase of the cycle of the cylinder marked "2nd";
Figure 8 shows the arrangement of Figure 7 advanced to the end
of the exhaust phase of the cycle of the cylinder marked
"lst";
Figures 9 and 10 show in detail a cross section and side view
of the line of intersection of the primary chambers; and
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Figures 11 and 12 show how the linear seals 18 pass each
other.
Referring to the drawings, the embodiment of the invention
shown, an in-line rotary piston engine comprises a frame 1. As may
be seen in Figure 1 the inner shape of the frame is a multitude of
circular arcs which describe four cylinders, herein referred to as
cylindrical chambers. The cylindrical chambers are arranged in
line. The inner cylindrical chambers are bigger in diameter than
the outer ones. The inner cylindrical chambers are referred to as
primary chambers, while the outer cylindrical chambers are referred
to as secondary chambers to distinguish them, wherever necessary.
As well, any objects contained by these chambers will be
appropriately referred to as primary or secondary. The cylindrical
chambers intersect along their lengths. The outer shape of the
middle part may be rectangular, although it is not shown in the
Figures.
In Figure 2 the frame is shown closed at its open ends by an
end wall 9 and a flanged end wall 10. Both end walls contain a set
of four holes each, the two sets being directly opposite. However,
the flanged end wall contains a notch placed halfway between the
inner two holes on the flanged side; this feature is not present on
the other end wall. The outer shape of the two end walls may be
rectangular, although it is not shown in the Figures. The shape of
the flange on the flanged wall may also be rectangular and it not
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need follow the edge of the wall as shown in Figure 2. The frame
1, end wall 9, and flanged end wall 10 fit together to define the
first housing. The arrangement can be held in place by bolts
running through the various parts; gaskets can be placed between
them to prevent any leaks from said first housing. However,
neither detail is shown in the Figures.
The frame 1 provides space for ignition chambers, locations
for sparkplugs, intake ducts, and exhaust ducts, as shown in Figure
1. Along each primary intersection line in the ignition chambers
there may be placed at least one sparkplug 6, which may be centred.
On each secondary intersection line directly to the right of the
primary intersection lines there is a location for the intake duct
2, inside which an injector 5 may be mounted. The intake duct may
be centred on the line. On each secondary intersection line
directly to the left of the primary intersection lines there is a
location for the exhaust ducts 6. The exhaust duct may be centred
on the line.
As may be seen from Figures 1 and 2, the four cylindrical
chambers of the first housing provide locations for the cylinders
7 and 8. The holes in the end walls of the first housing provide
locations for their shafts 11 and 12. The inner two shafts,
numbered 11, herein referred to as primary shafts, carry the
primary cylinders. The outer two shafts, numbered 12, herein
referred to as secondary shafts, carry the secondary cylinders;
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they may be smaller than the primary shafts.
The primary cylinders 7 are right circular paraboloids. The
term right circular paraboloid, as used in this disclosure, refers
to a right cylindrical object whose faces are parabolas, with the
single exception that the vertex and opposite extremity are
circular arcs. The position of the vertex of the parabola is given
by the distance between the primary shafts minus the radius of the
primary chamber. The extremity opposite the vertex has a curvature
radius almost equal to the radius of the primary chamber, so that
the primary cylinder can turn freely inside its chamber.
The secondary cylinders 8 are right humped dees. The term
right humped dee, as used in this description, refers to a right
cylindrical object whose faces are D-shaped with another D-shaped
protrusion on the flat side of the "D." The radius of curvature of
the round side of the dee is slightly less than the radius of the
secondary chamber, so that the secondary cylinder can turn freely
inside its chamber. The purpose of the D-shaped hump is to
accommodate the shaft 12 and ensure permanent contact of its
external surface with the external surface of said primary
cylinders.
All four cylinders, primary and secondary, are fastened to
their respective shafts. The cylinders are free to turn inside the
first housing; as well the shafts are free to turn inside the holes
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of the end walls of the first housing. The four cylinders together
with the inner walls of the first housing define the working
chambers of the engine. The working chambers are defined later in
the disclosure.
Each of the primary cylinders carries seals. As may be seen
from Figure 3 each primary cylinder may carry a pair of circular
concentric seals 17. As well, each primary cylinder may carry at
least two linear seals 18, which run along each of the side edges
and directly toward the centre of the primary shafts, to the outer
circular seal of said circular seals 17. In Figure 4 it can be
seen that each linear seal comprises three parts: two U-shaped
elements 18 and a bow-like element 19. The bow-like element fits
under the ends of the U-shaped elements as illustrated by the
drawing. The seals are pushed tightly against the walls of the
first housing by springs 20 mounted beneath them. Note that the
bow-like element is kept from flying off by the two U-shaped
elements.
Turning back to Figure 2 it may be seen that the engine
comprises another housing, referred to as the second housing. The
second housing comprises the flanged end wall 10 and a cover 13
which fits on the flanged end wall. The cover has a hole directly
opposite the notch in the flanged end wall. As well, it can be
seen that there is a shaft 14 which rests in the notch and is
supported by the hole in said cover. This shaft is referred to as
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the output shaft because it channels the power developed by the
engine away to be used. Because of the construction of the second
housing, the output shaft is located halfway between the primary
shafts, allowing for the gearing design illustrated by Figure 2.
Also, each of the primary and secondary shafts carries a gear 16,
each secondary shaft being geared to a primary shaft (hence, a
gearing ratio of 1:1). The output shaft carries a gear 21 which is
geared to the gears of the primary shafts. Figures 9 and 10 show
in detail the shape of the ignition chamber 4 at the intersection
of the primary chambers, so it allows the seals 18 to approach and
pass each other thus maintaining the seal, as shown in Figures 11
and 12.
To help explain the cycle of the engine the definitions of the
various working chambers must be given. For simplicity sake we
distinguish three chambers:
the intake/compression chamber is defined by one primary cylinder,
its respective secondary cylinder, and the inner wall extending
from the intake opening of the primary cylinder to the next
sparkplug,
the ignition chamber is defined by both primary cylinders and the
inner wall of the first housing in the immediate vicinity of a
sparkplug,
the combustion/exhaust chamber is defined by one primary cylinder,
its respective secondary cylinders, and the inner wall extending
from the sparkplug to the next exhaust valve, and
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the separation chamber is defined by a secondary cylinder and the
inner wall of its respective secondary chamber. These chambers are
dynamic because they vary in size throughout the cycle, as well as
position relative to the cylinders. As well, there may be some
overlap between the various chambers. Besides defining the working
chambers it is useful to distinguish between the different phases
of the cycle. Thus, we have the intake/compression phase, the
ignition phase, and the combustion/exhaust phase. The relationship
between phases and chambers is immediately obvious. To explain the
functioning of the engine let us consider Figure 1.
For the purpose of this description the primary cylinders are
rotating in a clockwise direction; they have been arbitrarily
marked 1st and 2nd, to distinguish them from one another. The
arrangement of Flgure 1 is advanced to the position shown in Figure
5, by means of a starter, not shown in the Figures. (After the
engine starts, some of the force necessary to advance the cylinders
is provided by their inertia.) In this position the
intake/compression chamber is full with the combustible mixture.
As soon as the first seal line, marked A, of the 1st primary
cylinder passes the intake duct, the compression of the mixture
begins. The compression phase continues until the linear seal A
reaches the extremity of the ignition chamber, marked C. This
arrangement is shown in Figure 6.
Once all the combustible gases have been compressed and forced
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inside the ignition chamber, the sparkplug may be fired. Note that
the sparkplug may be fired at any time after the intake duct is
closed, thus the mixture can be compressed to any desired pressure.
Because the exposed surface of the 2nd primary cylinder is greater
than the exposed surface of the 1st cylinder, the force of the
explosion will act in greater proportion on the 2nd primary
cylinder thus ensuring that the primary cylinder will move in the
clockwise direction.
After ignition has taken place the combustion/exhaust phase
begins, as illustrated in Figure 7. As the fuel is burned, the
pressure of the resulting gases forces the 2nd primary cylinder in
a clockwise motion. Also, the volume available to the residual
gases increases almost linearly (due to the shape of the primary
cylinder) which is ideal for an internal combustion engine.
Meanwhile, the intake duct of the 1st primary cylinder has opened,
by the passing of the linear seal marked B. Fresh air is starting
to flood the intake/compression chamber of the 1st primary
cylinder. As soon as the seal line marked B of the 2nd primary
cylinder passes the exhaust duct, the gases remaining after
combustion are being exhausted. This position is shown in Figure
8. By the time the B linear seal of the 2nd primary cylinder
passes the exhaust duct, the linear seal marked B of the 1st
primary cylinder passes the area of the ignition chamber. Fresh
air is already rushing through the intake/combustion chamber of the
1st primary cylinder, and now it can pass through the
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combustion/exhaust chamber of the 1st primary cylinder. The rush
of fresh air forces the residual gases of the combustion out
through the exhaust duct. The compression phase of the 2nd primary
cylinder is underway; the process is now similar to that of the 1st
primary cylinder.
Now, notice what happens to the separation chamber of the
secondary cylinder adjacent to the 1st primary cylinder. In Figure
6 it may be seen that the intake duct of the 1st primary cylinder
is already open. The fresh air that enters is forced in the
separation chamber of the secondary cylinder. At the same time the
combustion gases remaining after the combustion phase of the 2nd
primary cylinder are being forced out. Following the motion to
Figure 7 it can be noted that the separation chamber is now closed
and filled with fresh air. Any residual gases that may be forced
between the secondary and primary cylinders will be force out with
the residual gases remaining after the combustion of the 1st
primary cylinder. By the time the position of Figure 8 is reached
the gases that remain in the combustion/exhaust chamber are only
the fresh air; as well the gases in the separation chamber are
fresh air. Thus, all the residual gases, or at least the greatest
part, have been cleaned from the engine. A new, fresh cycle for
the 1st primary cylinder is about to begin.
Consider now what happens in the second housing. As the
primary cylinders turn clockwise, their shafts and gears also turn
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clockwise. The secondary gears, and through them the secondary
shafts and cylinders are forced to turn counter-clockwise, as
illustrated in the various Figures. We have only assumed that they
turn counter-clockwise; however, the construction of the second
housing ensures this fact. As well, the output shaft placed
between the two primary shafts is forced to turn counter-clockwise.
While the 1st primary cylinder is in the intake/compression phase
it does not develop any power. However, the 2nd primary cylinder
does, as it just enters its combustion phase. But as the 2nd
primary cylinder is forced clockwise by the expanding residual
gases, it also turns the output shaft. In turn, the output shaft
turns the shaft of the 1st primary shaft. As it may be seen one of
its purposes is very much like the purpose of the crankshaft of a
four-stroke engine. However, unlike the crankshaft, the output
shaft also (directly) channels the energy away from the engine - to
be used.
A feature of the engine is immediately obvious. Because after
each cycle most, if not all, of the residual gases are eliminated,
a greater percentage of oxygen is available for combustion. This
fact in turn leads to a cleaner combustion meaning less pollutants.
As well, note that there are no valves required for the intake and
exhaust ducts. Hence, more useful energy is available. Finally,
the construction of the engine is simpler than that of a four-
stroke engine. This will eventually translate to a lower cost
engine.
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Although only a single embodiment of the present invention has
been described and illustrated, the present invention is not
limited to the features of this embodiment, but includes all
variations and modifications within the scope of the claims.
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