Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: SYNCHRONOUS TWO-STROKE "SERVO PISTON" SERVICE UNIT WITH FLOATING
RING FOR ENDOTHERMIC ENGINES
Technology field which the invention refers to
The mobility and the intended use of the unit presented is aimed at all
those vehicles equipped with internal combustion engines in a condition
of what can be moved in relation to space-time movement. It is employed
for transportation in general, for leisure, for work and for sports
competitions, in relation to people or things.
The state of the art and the preexisting technology of the two-stroke
engine
The age of the two-stroke engine, as is well known, is slowly drawing to
an end, abandoned by the majority of the motor industry despite the
capacity that this system is still be able to express and despite it
appearing to be still valid from the point of view of versatility,
compactness and constructive simplicity, which dictated a low-cost
production and sale. However, a strong use still remains in environments
in which environmental regulations are less restrictive, for instance for
motocross competitions in the mountains, for boats in the nautical field
and for snowmobiles on the snow but, as for road use, nowadays it has
been abandoned even for motorcycles.
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The state of the art and the preexisting technology of the four-stroke
engine
The demand for increasingly efficient and clean engines and the economic
and sports competition have led the evolution of this type of engine to
high levels, especially for the exasperated use of the turbo compressor
which, although it brings benefits at a functional level, cannot be said
to be also successful in containing polluting emissions. As a matter of
fact turbo engines, by exploiting the exhaust gas pressure, decrease the
ability of gases to be filtered. And it is logic to think that this
matter has come to a climax and that further developments in that
direction will gradually decline given the advance of electric battery-
powered propulsors.
Technical problem with the two-stroke engine
The reasons for the decline of the two-stroke engine are: the severe
anti-pollution regulations in force in the cities and in the inhabited
centers, high consumption and the burden of adding oil to the fuel.
Recently, there have been patents attempting to address the
inefficiencies of the two-stroke engines by employing counter pistons,
which oppose each other with complex mechanisms in order to set into
motion the relating laborious devices which, in order to function,
require unique systems built on purpose like: crankshafts in series,
articulated joints, rotating valves, pipe supports with sliding rods,
connecting rods, double arm with variable geometry movements, separated
prechambers, high-pressure supply systems and dedicated turbo
compressors.
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The solutions are different from each other but they need to be suitably
manufactured and employed in engines specifically constructed for the
purpose. All of these patented sophistications are not easy to implement
due to the complexity of the mechanisms to be produced, to the design and
production costs and to the practical and economical benefits, and
probably they are even far from the creators' intentions.
Technical problem with the four-stroke engines
A symptomatic factor that slows down the evolution of the four-stroke
engine is certainly determined by the mushroom valves which, though still
indispensable, at the same time set limits due to their inefficient
function; they absorb part of the energy produced and waste heavy amounts
of fuel for their own cooling at higher speeds and result in further
waste during the so-called "crossover" phase. They exclusively work with
specific fuels with a higher octane rating as a consequence of the auto
ignition caused by high working temperatures.
Description of invention - The synchronous two-stroke "servo piston"
service unit with floating ring (1) proposes the employment of a two-
stroke propulsion system for endothermic engines by exploiting the full
power that the system possesses. This new technology is sustainable, it
complies with the strict regulations in force and it is accessible in
large scale with low-cost design and production thanks to the extreme
simplicity of construction and to the great benefits offered. The
invention, unlike its two-stroke direct competitors which propose similar
systems in the light of the actual state of the art, presents itself with
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very simplified mechanics of movement, it is compatible with the current
technology of distribution employed in modern four-stroke engines and it
uses the same components, but larger and heavier. But what is even more
innovative, which makes it different from other systems, is the way the
fresh charge (air/fuel mixture) is introduced into the cylinder, in fact
this new system provides for the inflow of the fresh charge through a
lamellar valve located at the top of the cylinder chamber (2/3) which,
thanks to the depression generated by the servo piston moving downwards
from the TDC to the BDC during the suction stroke, introduces directly
the mixture thus filling up the cylinder chamber completely (2/5). Once
the mixture has been preloaded and pressurized, the servo piston moves
back up from the bottom dead center and the scission stroke occurs, that
is to say that the servo piston decomposes into two sections, the
external ring separates from the central disc in traction which is braked
by the friction generated by the compression rings coming into contact
with the cylinder wall (2/6). In this circumstance, once the cylinder
chamber depressurizes, the servo piston is able to move back up to the
TDC through the fresh charge previously sucked up and to pour the latter
downwards from the upper part of the cylinder itself (2/7-8), thus
turning the preload into the fresh charge, and then it reassembles as one
element at the end of stroke forming the top of the cylinder head (2/9).
Unlike the modern four-stroke engines, the advantages of this system lie
in the fact of being able to use more ecological and alternative fuels
benefiting from the absence of the overhead mushroom outlet valve which
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considerably overheats to the passage of the exhaust burnt gases.
Moreover additional benefits are derived during the gas exhaust stroke
which takes place from the lower point of the cylinder (2/5), in fact
exhaust gases remain less time in the cylinder chamber and, once they
have expanded after the detonation, they directly flow out in only one
stroke as they are no longer pushed back up to the outlet valve, which
avoids the resulting overheating of the head due to heat radiation and,
as a consequence, having to use specific antiknock fuels with a higher
octane rating. Thanks to the cold head (less hot) one profits from a
higher compression ratio with a resulting better thermal efficiency in
comparison to the current combustion engines in which only about a third
of the energy developed during the combustion of the air-fuel mixture is
transformed into mechanical energy, the rest of it ends up unused, wasted
in the outlet or transferred to the cooling system. At last, a further
benefit one can get from the servo piston is that the turbo compressor is
not employed, in fact the exasperated use of the latter in modern four-
stroke engines in order to increase the power leads to a reduced ability
to catalyze discharges due to the pressure drop and to the substantial
increases in size and costs.
THREE-STROKE SYSTEM - The system architecture has been designed on the
basis of the S/P's peculiarity, which is to carry out two simultaneous
activities (plus an extra one) out of the four functional thermodynamic
strokes of the Otto cycle named "service strokes", which comprise the
fresh mixture suction stroke simultaneously combined with the burnt
gas(2/3-4-5) exhaust stroke and an extra one called "scission", hereafter
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explained. The remaining strokes, those of compression and expansion
called "active", are dependent on the power unit represented by the
principal piston.
PROPULSION FUNCTION - The work carried out by the S/P in the cylinder
chamber is comparable to that of a plunger turned upside down which moves
in a rectilinear reciprocating motion with its direction parallel to the
major axis of the cylinder (in this case, by way of example, in vertical
direction) from the TDC to the BDC and vice versa, opposite and
synchronized to the primary piston, and operates with a rapid motion. In
fact it acts as a propulsor which is able to generate at the same time
pression and depression in one motion from top to bottom, it is
subordinated to the turn of an altered overhead camshaft and subjected to
a derivative desmodromic mechanism.
DISTINGUISHING CHARACTERISTICS
PASSIVE FUNCTION - As for the moving central section of the S/P, (1/7)
the particular installation of this unusual device allows the pouring of
the fluid mass (fresh charge) into the same cylinder, it opens when
moving upwards during the service stroke, thus carrying out a singular
function understood as "scission"(2/6). The automatism of this section is
developed in a dynamic way from a mass that moves by inertia and that
becomes compact when moving downwards and decomposes into two sections
when moving upwards: the central part, which is well fixed to the rod,
shaped like a circle and the external part shaped like a floating ring
(1/7).
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COMBUSTION CHAMBER - In other words it is the space that takes shape when
the S/P is in the top dead center TDC (end of stroke), at that moment it
assumes the shape and the function of head, thus forming the upper
section of the cylinder chamber. Right at the time the end of stroke is
reached in the TDC, in the head the S/P temporarily forms the top of the
combustion chamber (2/9), namely the space in which the air-fuel mixture
is confined at the end of the P/P's compression stroke.
TWO-STROKE - It is determined that with the above-mentioned
specifications one has the capacity to employ a sole thermodynamic cycle
for one complete turn of the camshaft, therefore this functionality is
characterized by the two-stroke principle.
THE BORE AND THE STROKE LENGTH - The geometry of the architecture is
designed by calculating the margins of the kinematic process, which is
expressed by the value of the "Superquadro" ratio (short-stroke) since
the bore value is bigger than the stroke length. This choice is the ideal
solution that brings: functional benefits, a decrease in the excursion of
the S/P and consequently a reduction in the volume of the organs
connected to it.
ANTI-SEIZURE - The S/P is not particularly exposed to the complication of
the seizure as it operates attached to the rod (1/1), which moves it in a
perfectly linear way, exempt from lateral forces, favoured moreover by
its ability to rotate on its own axis. In addition to that, in order to
prevent seizure and ensure the lubrification, one row of ball bearings is
encased in a groove that encircles the S/P (1/10) and they are immersed
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into a special grease for high temperatures (like molybdenum disulphide)
which makes the motion smoother and reduces the friction with the
cylinder pipe. The whole is closed, partitioned and hermetically
protected between two compression rings ( 1/8-9) of the synthesized type
(carbide, tungsten and steel alloy).
SIZE - The circumference is the same as the bore of the primary piston.
Thicknesses and weights are situational, defined by the design values,
the condition of use and the materials employed.
QUICK AND ACCURATE - These adjectives sum up the reactive nature of the
S/P unit and the steadiness of the perfectly linear stroke. These
benefits are achieved thanks to the fact that the S/P is not attached to
a connecting rod but to a linear rod (1/1) and thanks to the consequent
absence of lateral forces (given by the effect of flaring due to the
upward and downward motion generally related to pistons).
THE HOUSING - The section is defined as the seat of the S/P in the point
of upper end of stroke TDC, it draws an analogy with the valve seat of
the four-stroke engine from which it takes the technology and the
materials employed for the making of this section.
THE SPARK PLUG - It is laterally located for the positive ignition of the
combustion and appropriately housed in the upper part of the cylinder, in
the combustion pseudo-chamber, therefore it is no longer in the head but
it is laterally located, which is an obliged solution to allow the
passage of the S/P.
THE MATERIALS AND THE SHAPE - Aluminium alloy forged, from an aesthetic
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point of view it is similar to a big mushroom valve where, at the center
of the disc, is evident a circular intersection. The latter in fact is
the passive valve with a tail which is represented by a sturdy linear rod
(1/1), whose extremity is predisposed for the contact of the equalizers
(2/3). The whole surface is enclosed by the two compression rings (1/8-9)
which contain the row of inox ball bearings (1/10).
THE COOLING - In addition to the centralized system of the engine that
also cools the cylinder, the S/P enjoys a further benefit due to a
thermic exchange and achieved by the fresh charge both during the suction
stroke and the scission stroke.
INTEGRATED SYSTEM - All the technologies described in this report take
shape in the upper section of the four-stroke engine. The remaining
components, which are normally employed for what they have been designed,
remain unchanged and they are the pistons, the connecting rods, the
camshaft, the change gear, the clutch, the transmissions, the electronic
injection, the radiators, part of the distribution, all the electric
system of lubrification and the cooling, etc...
The following study in depth is pointed out by simulating the employment
of the S/P in a vertical single-cylinder spark ignited petrol fuelled
two-stroke engine.
In order to get optimum efficiency from this new technology for the
construction of a modern engine, two old technologies have been selected
along with a third traditional mechanical organ whose functions are
connected with each other and carry out combined actions. It is specified
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that the S/P is an individual organ which is an end in itself; the
connected technologies, hereafter explained, are not binding to its
functioning and it can be connected to any device that puts it into
motion, be it mechanical, electric or pneumatic in order to get the
above-mentioned benefits.
THE FIRST TECHNOLOGY - The choice of the S/P's command system falls on
the derivative of a little known system of distribution named
"desmodromic". It is distinguished by an essential characteristic, the
employment of a faster and more accurate recall mechanical method of the
valves; the size of such a system is not sufficient so it is implemented
with a structural oversizing, proportionally at an approximate scale of
1:5, notwithstanding the faithfulness to the criterion which it has been
invented for. The whole architecture has been clearly designed for an
accurate synchrony of the S/P subordinated to the stroke rate of the P/P,
which follows the stroke with a uniform and regular rhythm.
THE RATE - Appropriately calibrated, the S/P's command system balances
the travel with only two movements (push and pull) with a different
rhythm and it is run by a single two-cam shaft setting. Being conceived
in this way, it is able to develop a greater load with the necessary
energy amplifying the range of action of the equalizer and thus
increasing the excursion.
PERTINENT- It is involved, in the same context, a third element as well,
an aid-worker of the overhead activity, namely the common "camshaft"
which interfaces among the parts creating a connection: constrained in U
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the new architecture, it gets altered as well and in fact, by getting
elaborated, its size gets enlarged, specifically the one of the cams
(eccentrics) which are definitely much larger, in order to allow a longer
excursion on the two independent equalizers (arms), which in their turn
operate alternately on the axis of the S/P.
THE SECOND TECHNOLOGY - In order to optimize the S/P's potential at its
best, a very versatile passive (it does not absorb energy) one-way
distribution device has been adopted and re-used, better known as
"lamellar pack", originally used in many two-stroke engines (and air
compressors), mainly during the suction stroke (fresh mixture), but now
it is also employed as outlet valve, located on the burnt gas outlet pipe
at the base of the cylinder. It is made up of a series of lamellae (in
carbon, steel, fibre, etc.) which regulate the fluid dynamics of gases
that enter the two-stroke engine cylinder.
THE FUNCTIONING - As for the inflow stroke, the principle is similar to
the employment in the traditional two-stroke engine but in different
modes and times, the function occurs during the stroke in which the S/P
moves downwards, therefore in the cylinder chamber a depression is
generated and the lamellar valve, which is located at the top in the
cylinder pipe, opens up in the inward direction of the cylinder itself,
thus favouring the inflow of the fresh charge, and closes up again once
the depression ceases due to the filling of the cylinder chamber. In the
next stroke, the exhaust one following the detonation and the gas
expansion, a resonance, which produces a pressure increase in the
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cylinder, is generated; the lamellar valve, which is located on the
outlet in the lower part of the cylinder pipe, by receiving pressure,
opens up in the outward direction allowing the burnt gas evacuation and
after that it immediately closes up, once the pressure ceases and the S/P
moves back up.
THE THREE FUNCTIONS CARRIED OUT BY THE SERVO-PISTON
A) THE EXHAUST - Starting from the TDC, the device intervenes with a
little delay after the detonation by calculating the gas expansion time
coefficient, the gases give the push to the P/P in the downward stroke,
followed by the S/P, which on the contrary is moved by the pulse received
from above (camshaft-desmo combo) and by the dynamic suction backpressure
(drag phenomenon determined in a gas mass) generated by the wave. During
the stroke from top to bottom the S/P, driven by pressure, from the "X"
side quickly pushes the exhaust burnt gases outwards to the lamellar
valve (lamellar pack), which has meanwhile opened up following the
pressure exerted on it, and to the outlet.
B) THE SUCTION - In the course of the cleaning (exhaust) stroke, which
takes place on the "X" side of the S/P, at the same time on the "Y" side
the other phase of work occurs, namely the suction (the inflow of the
fresh charge, the fuel); the S/P slowly pushes the burnt gases from the
"X" side and simultaneously from the "Y" side sucks up the reload. The
latter moves down into the empty space, favoured by the depression
generated, which in its turn has enabled the lamellar inlet valve
(located at the top) to open inwards, thus favouring the inflow of the
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fresh charge (air/petrol mixture or other fuel) directly into the
cylinder chamber and allowing the complete filling; at that point the
lamellar inlet valve closes up following the lack of depression. Once the
servo-piston reaches the BDC, it has completed the two first phases of
the first stroke.
C) THE SCISSION - It is the division of the S/P into two parts, basically
it is a new supplementary stroke. This function is possible thanks to the
passive valve that allows the advent of the new function, which does not
belong to the well-known thermodynamic cycle, and it is precisely
described as "functional service stroke". The dynamic process is carried
out in the following way: once the BDC is reached (namely the position
where the P/P and the S/P are opposite one another), after having
discharged the gases to the outlet and preloaded the cylinder chamber
with the fuel from the "Y" side, the S/P moves back up a little in
advance of the P/P (drawn back up by the camshaft/desmo combo) and
generates a turbulence which pours the mass of particles (fresh charge)
into the chamber after passage through the opening of the passive valve.
The manoeuvre occurs thanks to the braking given by the friction of the
S/P's external section compression rings coming into contact with the
cylinder chamber's sheath (dragged by leash).
Once the stroke is completed, at first the central section of the S/P
(valve) houses in its end of stroke in the TDC and immediately afterwards
the external section aligns again to the central one, thus reassembling
the S/P, thanks to a spiral spring inserted between the two parts (1/12)
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and to the compression thrust given by the following piston.
FUNCTIONAL EVOLUTION OF THE PRIMARY PISTON
The role played by the power unit (primary piston) in the cylinder
chamber in association with the fellow S/P is scaled down to only two
active strokes and the piston rate is completely the same if compared to
the four-stroke engine, but the background changes. The difference in the
process is not made by the piston in itself with its reciprocating motion
but by its fellow S/P, which with its aid reduces the strokes from four
to two increasing the active work of the piston during the charge
compression stroke and the expanding pressure stroke and making itself
responsible for the two service strokes, as already described. The shape
assumed by the piston, which best fits for this employment, is the Cupa
type (like the diesel), characterized by a short skirt with concave top,
and it allows to best collect the combustible mixture at the center of
the piston, which best absorbs the expanding gases thus limiting the
recoil, namely the pressure heading in the opposite direction.
KINEMATIC SEQUENCE OF THE THERMODYNAMIC PROCESS
1st Stroke Regular/lst Action/it Phase/Expansion/Downwards/Picture 2
Once the optimum point of compression in the cylinder chamber is reached
(2/2), in the TDC the spark goes off and immediately the detonation of
the fuel mixture occurs, followed by the burnt gas volumetric expansion
stroke, and the piston moves downwards (2/3-4) reaching the BDC (2/5),
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thus already completing half turn of the camshaft.
1st Stroke Del. /2nd Action/2' Two-phase/Exhaust/Downwards/Picture 2/X Side
Afterwards, in the same first stroke, the S/P follows the action of the
P/P (2/3-4) downwards with a little delay (Del.) carrying out the exhaust
stroke from top to bottom and pushing the burnt gases towards the
lamellar outlet valve (2/5).
1st Stroke Del. /2' Action/2' Two-phase/Suction/Downwards/Picture 2/Y Side
At the same time the S/P, in the same above-written action always from
top to bottom, from the "Y" side carries out the fresh charge (fuel)
preload retro suction stroke (being the fresh charge introduced by a high
depression) filling all the space of the stroke from top to bottom in the
same cylinder chamber (2/3-4-5).
2' Stroke Advance/3' Action/3' Phase/Scission/Upwards/Picture 3
This completely new stroke, named scission, consists of the advance
restart of the S/P from the BDC right before the piston which, by
decomposing into two sections and opening up its central valve, manages
to move back up cleaving the fresh charge, poured from the "Y" side to
the "X" side, to move back into its seat at the end of stroke in the TDC
and then to reassemble, thus forming at that point the top of the head.
2' Stroke Regular/4th Action/4th Phase/Compression/Upwards/Picture 3
Finally the primary piston follows the servo-piston upwards pushing the
fluid mass, which is in stasis condition, by compressing it to the top
close to the S/P which, at that moment, serves as head (moved by the
camshaft that has meanwhile completed the turn).
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THE SYNTHESIS - The sequence of events previously described starts with
the piston moving down during the expansion stroke, the S/P follows it
and from the "X" side pushes the discharged exhaust gases to the outlet
and, at the same time, completes the filling of the cylinder chamber by
sucking up the fresh charge from the "Y" side, then it moves back up
during the scission stroke followed by the piston, which in its turn by
moving upwards pushes and compresses the fresh charge to the top close to
the S/P. At the time when the S/P and the P/P reach the TDC, once the
optimum point of compression is achieved, the spark goes off and ignites
the fuel, which by imploding generates the expansion wave. Then it starts
again for the following turn of the thermodynamic cycle according to what
has already been said about the functioning of this new system.
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