Variable compression ratio internal combustion rotating engine

A variable compression ratio rotating engine comprises a containing cylinder forming variable volume chambers, defined by the cylinder inner wall and piston side walls, the cross-section of which has substantially the shape of a circle sector. During the operation of the engine, the pistons are rotated with an uneven circular motion, by a mechanism including a crank, having an eccentric axis with respect to that of the containing cylinder, and small coupling rods coupling the arms of the crank and the end portions of small shafts passing through the pistons, the compression ratio being changed by means of a further mechanism able of changing the eccentricity value of the crank axis with respect to the cylinder axis.

BACKGROUND OF THE INVENTION 
This is a continuation-in-part of U.S. application Ser. No. 057,006 filed 
on June 1, 1987, in the name of the same applicant, now abandoned. 
The present invention relates to a rotating internal combustion engine 
provided with means for varying the compression ratio. 
As is known, there are presently available the so-called Wankel type rotary 
engines which, however, have great drawbacks with respect to the gas 
tightness and do not afford the possibility of affecting, by modifying the 
variable volume chamber shape, the combustion conditions of the air/fuel 
mixture, depending on its turbulence and the formation of a proper flame 
front. 
Moreover, these Wankel engines do not achieve very high compression ratio 
and they do not fully exploit the gas expansion force, because of the poor 
radial extension of the surface affected by the gas active pressure. 
There are also known further rotary engines such as that disclosed in the 
U.S. Pat. No. 3,685,928 granted on Aug. 22, 1972 to Munzinger. More 
specifically this patent discloses a rotary piston engine, including a 
plurality of cylinder forming annular elements and a plurality of annular 
segment piston pairs, the segment piston of each pair moving inside one of 
said cylinders and having disc shaped articulated elements bearing against 
each other and defining together with their circumferenatial surfaces the 
inner wall of the corresponding cylinder, the hubs of one of the segment 
pistons of each pair having shaft portions axially extending therefrom and 
forming outer hollow shaft means and the hubs of the other pistons of each 
pair having shaft portions extending axially therefrom which form inner 
shaft means, the shaft portions of the inner shaft means being supported 
within the shaft portions of the outer shaft means, separating elements 
between each pair of piston segments forming the end walls of the 
cylinder, a common shaft, means operatively coupling the outer shaft means 
and inner shaft means to the common shaft, the hubs of the inner shaft 
means being provided with annular recesses therethrough at the same 
spacing from the axis of the shaft means as the distance separating the 
shaft walls of the outer shaft means, the shaft portions of the outer 
shaft means having axial projections on a side thereof extending through 
and with a circumferential size less than that of said annular recesses, 
the shaft portions of the outer shaft means having recesses therein on the 
opposite side from said annular recesses, the projection of one of the 
outer shaft means extending through said separating means and engaging in 
the recess of the subsequent shaft means, the shaft portions of the inner 
shaft means having means engageable thereon by an axial displacement 
thereof in order to connect them for jointly rotating. 
In this patent the two pistons operating in each cylinder rotate with a 
cyclically variable speed: however, as clearly stated in claim 2 of this 
patent, the single pistons operating in different cylinders are coupled on 
the same axis with such an angular displacement that each piston has, with 
respect to the adjacent piston of the adjacent cylinder, an angle equal to 
the ratio of 360.degree. and the number of the cylinders of the engine. 
Accordingly, this mechanical arrangement provides a maximum compression 
condition in the several engine cylinders for mutually fixed angular 
positions. 
This construction has been selected by Mutzinger in order to obtain an 
equilibrium condition of the main rotating masses of the engine. 
On the other hand, such a mechanical construction constrains the size of 
gas ducts and provide said ducts with two elbows each, since the engine 
cylinders are arranged along the same axis. 
Thus, the main object of the present invention is to overcome the above 
mentioned drawbacks of known rotary internal combustion engines, by 
providing such a rotary engine in which all of the component parts are 
perfectly balanced, both from the static and from the dynamic standpoint, 
with a very simple mechanical construction. 
Another object of the present invention is to provide such a rotary engine 
the pistons of which are so arranged and balanced as to locate the maximum 
compression angular position of the cylinders at a zone adapted to greatly 
reduce the gas duct length. 
Another object of the present invention is to provide such a rotary engine 
including means for homologously coupling the engine pistons so as to 
provide an identical movement pattern for the coupled pistons and 
identical variations of the movement pattern as the engine compression 
ratio is changed. 
Another object of the present invention is to provide such a rotary engine 
which has a high power jointly with a very even torque, both owing to the 
possibility of obtaining a greater number of complete operating cycles for 
each revolution of the driving shaft and a high rotation speed as a 
consequence of a complete elimination of the engine reciprocating masses. 
Another object of the present invention is to provide such a rotary engine 
which does not comprise valve means, which would be not compatible with 
high revolution speeds, and in which the gas passage ports can be 
constructed with a comparatively large size. 
Another object of the present invention is to provide such a rotary engine 
having a compression and scavenging ratio much larger than that of a 
conventional two-stroke engine with a complete independence of the angular 
duration of the respective phases of the operating cycle, which has been 
obtained, according to the invention, by using two identical mechanisms 
held in separated and adjoining cylinders, in which one of these mechanism 
operates to suck and compress the fresh mixture, while the other mechanism 
operates as a combustion-expansion mechanism, this mechanical arrangement 
affording a great reduction of the dead spaces of the gas ports, a 
complete elimination of the fresh mixture loss, since the scavenging is 
performed by not carburetted air, and an increase of the burnt gas 
expansion phase. 
Another object of the present invention is to provide such a rotary engine 
which can operate with different types of fuels, by instantaneously 
adapting the compression ratio to the characteristics of the selected 
fuel, thereby practically providing an effective multiple-fuel engine. 
Another object of the present invention is to provide such a rotary engine 
with a very reduced atmospheric pollution, owing to the possibility of 
fitting the compression ratio to the load of the engine, mainly for low 
revolution speeds. 
SUMMARY OF THE INVENTION 
According to one aspect of the present invention the above mentioned 
objects, as well as yet other objects, which will become more apparent 
hereinafter, are achieved by a variable compression ratio internal 
combustion engine comprising at least two cylinders defining variable 
volume chambers encompassed by the inner wall of the respective cylinder 
and the side walls of the pistons the cross-section of which, according to 
a plane perpendicular to the main axis of the cylinder, has substantially 
the shape of a circular sector or segment. 
The engine pistons, in particular, are rotated with an uneven circular 
motion by a mechanism including a crank, having an eccentric axis with 
respect to that of the cylinder, and by coupling rods coupling the crank 
arms and the end portions of small shafts passing through the pistons, 
means being moreover provided for varying the compression ratio and 
operating on the variation of the eccentricity of the crank axis with 
respect to the cylinder axis.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference to the figures of the accompanying drawings, the variable 
compression ratio internal combustion engine according to the present 
invention comprises at least two cylinders, more specifically an engine 
cylinder proper and a compressor cylinder, which are provided with a liner 
26 in which there are arranged the pistons 2 coaxially rotating therein. 
As shown, the cylinders and pistons define a plurality of variable volume 
chambers. 
More specifically, these chambers are encompassed by a portion of the inner 
walls of the respective cylinders and by the side walls of the pistons. 
The pistons 2, in particular, have, according to a cross-section taken 
perpendicularly to the axis of the cylinders 1, a substantially circular 
sector shape. 
Advantageously, according to one aspect of the invention, the radial 
surfaces of the pistons defining said chambers can be specifically 
designed, in a conjugate manner, so as to improve the combustion 
conditions inside the chambers, in order to reduce the inlet loss at the 
gas ports, which will be described in a more detailed way hereinafter. 
In particular, through the cylinder 1 there are formed the inlet port 20, 
the transfer port 21 and the outlet port 22 and scavenging port 12, there 
being moreover provided a housing for receiving the sparking plug 23 
and/or the fuel injector member. 
As shown, the gas transfer port 21 has, owing to the adjoining arrangement 
of the cylinders, a great cross-section adapted to provide small gas 
speeds and accordingly a very reduced loss even for high revolution speeds 
of the engine, with a very short length to reduce to a minimum the dead 
volume. 
Inside the cylinder 1 there are arranged a plurality of pistons 2 
including, for each cylinder, at least two units; in the accompanying 
drawings there being illustrated three pistons, each of which rotates 
about a central shaft and is coupled thereto through ring members 27. 
With the driving shaft 4 there is rigid a crank 3, able of rotating about 
an axis which is eccentric with respect to the axis of the cylinder. 
The engine further comprises suitable sealing members, consisting of discs 
7 which are coupled to one another by means of a hollow shaft 28, circular 
rings 8 and rectangular cross-section ring members 9, as well as further 
rings 25. 
Each piston is coupled, through the sealing members, to a respective 
counterweight 10 which operates to statically and dynamically balance the 
piston itself. 
The pistons of the engine cylinder and those of the precompressor cylinder 
are coupled to one another by means of suitable kinematic members which, 
for example, comprise driving gears 11 and driven gears 13. 
Furthermore there is provided a mechanism for varying the compression 
ratio, which mechanism is supported by a front plug member 14, and can 
advantageously comprise a rack 15-worm screw 16 assembly. 
At the rear, there is provided a plug member 17 rigid with a centering 
shaft 18. It should be pointed out in this connection that from the 
drawings there have been omitted the lubricating system ducts, since they 
are not necessary for understanding the operation of the assembly. With 
respect to the cooling system there is exclusively represented the gap 19 
included between the cylinder 1 and outer liner 29, in which a cooling 
fluid would be able to circulate. 
The rotary internal combustion engine according to the present invention 
operates with the following phases or strokes:after the combustion phase, 
in the chamber having the minimum volume configuration and with a suitable 
spark advance, the pistons 2 are caused to rotate. This rotation is 
transmitted by said pistons, through the small shafts 6, from one side, to 
the coupling rods 5 (each balanced by an end balancing counterweight 24) 
and hence to the crank 3 and driving shaft 4 and, from the other side, to 
the members provided for transmitting motion or driving the pistons of the 
precompressor, for example through the gears 11 and 13. 
This rotary movement occurs about the centering shaft 18, which is coaxial 
with the cylinder. 
Thus the small shafts 6 are caused to move along different length 
circumference arcs, in equal times during a full revolution of each 
piston: because of this reason, the pistons, as they rotate, will move to 
one another and away from one another alternatively, thereby causing the 
volume of the chambers encompassed by the radial walls of the pistons and 
inner wall of the holding cylinder to vary. 
This volume variation will depend on the eccentricity of the driving shaft 
with respect to the axis of the cylinder; accordingly it will be 
sufficient to vary said eccentricity in order to change the compression 
ratio, theoretically from 0 to infinite. 
In actual practice, this ratio may be changed within sufficiently broad 
limits to afford the possibility of fitting the characteristics of the 
subject engine to all of the possible requirements of the operation of any 
internal combustion engines. 
According to a further characteristic of the present invention the two 
pluralities of pistons (engine pistons and precompressor pistons) have 
preferably opposite turning directions, in order to completely suppress 
possible vibrations at high revolution speeds, each piston of the cylinder 
in which there is carried out the combustion being kinematically coupled 
to the corresponding or homologous piston of the cylinder in which there 
is carried out the suction or intake step so as to immediately and 
identically transmit any movement variation. 
In the drawings there has been illustrated, by way of an indicative but not 
limitative example, one of the several possible mechanical approaches to 
vary the compression ratio, even as the engine is operating. 
More specifically, the complete operating cycle number, for each revolution 
of the driving shaft, will be equal to the number of the chambers and 
hence of the related pistons; thus, in the exemplary embodiment shown in 
the drawings, the cycles will be three for each revolution of the driving 
shaft. 
Tightness or sealing of the engine parts, which are always slidingly 
contacted on extended surfaces, is assured by suitable labyrinths formed 
by resilient rings of any suitable types: those of rectangular 
cross-section shape 9 are held in contact against the surface thereon they 
must slide by means of springs 30 effective to cause said rectangular 
cross-section parts to abut on said surface even if the engine is in a 
stop condition, whereas, as the engine operates, they will be pushed 
further into contact because of the centrifugal force actine thereon. 
The device which permits to achieve this condition also for the rings or 
bands arranged on the front flat surfaces of the pistons is schematically 
shown in FIG. 9 and consists of a metal mass 32 pressed in the direction 
of the central axis by the spring 31 which is pressed as the engine 
operates by the centrifugal force acting on the mass 32 which will push 
outwardly the corresponding ring member 9. 
From the above disclosure it should be apparent that the present invention 
fully achieves the intended objects. 
In particular, the variable compression ratio rotary internal combustion 
engine according to the invention has been specifically designed to afford 
a high rotary speed operation. 
Accordingly, a great effort has been made in perfectly balancing the 
rotating masses, which problem has been satisfactorily solved by causing 
the pistons in the two cylinders to rotate in opposite directions, after 
having removed, because of constructional reasons, the originally provided 
counterweights. 
A like effort has been made to properly study the gas dynamic flows, with a 
consequent increase of the gas port cross-sections and a rational 
arrangement of these ports, with the cylinders arranged adjoining one 
another. 
These two obtained conditions, together with the fact that there are 
performed three complete cycles for each revolution of the driving shaft, 
which means that in each time of the engine operation there occurs an 
active expansion of the burnt gases, allow for the subject engine to 
achieve very high specific power values, with respect to those obtained 
with conventional piston engines, with a very reduced fuel consume. 
The shape of the surfaces of the pistons which define the two movable 
surfaces of the combustion chamber can be broadly changed, provided that 
there are selected mutually conjugate surfaces in order to improve the gas 
flow, turbulence and flame front pattern to improve in turn the combustion 
conditions and decrease the inlet loss at the gas ports. 
In actual practice the sole limitation to the performance of the engine 
according to the present invention derives from the efficiency of the 
cooling system which can be improved by using a ceramics material for the 
strongly thermally stressed engine parts, such as the pistons. 
While the invention has been disclosed and illustrated with reference to a 
preferred embodiment thereof, it should be apparent that the disclosed 
embodiment is susceptible to several modifications and variations, all of 
which will come within the spirit and scope of the appended claims.