WO2016055923A2

WO2016055923A2 - Axial piston internal combustion engine

Info

Publication number: WO2016055923A2
Application number: PCT/IB2015/057610
Authority: WO
Inventors: Calogero Provenzano
Original assignee: Calogero Provenzano
Priority date: 2014-10-09
Filing date: 2015-10-05
Publication date: 2016-04-14
Also published as: WO2016055923A3

Abstract

Herein described is an axial piston internal combustion engine (1; 100) comprising a motor unit (M) and a compressor unit (C). The compressor unit (C) is configured to take in an airflow, compress the same airflow and transfer it to a motor unit, where it is burnt mixed with the fuel to obtain a duty cycle. The displacement of the compressor unit is variable so as to regulate the airflow taken in by the engine (1;100) and processed by the motor unit (M).

Description

"Axial piston internal combustion engine"

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DESCRIPTION TEXT

Field of the invention

The present invention relates to axial piston internal combustion engines.

Prior art and general technical problem

The prior art offers various examples of axial piston internal combustion engines. Known examples are found e.g. in documents FR 2 828 711 Bl, US 5, 507, 253 and US 8,230,827.

All engines subject of the aforementioned documents are characterised in that they are of the opposed piston type, i.e. wherein the combustion chamber is defined between the cylinder walls and the crowns of two opposed pistons facing one another. In other words, the same cylinder is shared by a pair of pistons, which is susceptible of introducing severe limitations under the very design point of view, as well as in terms of possibility of adjusting the engine .

In addition, documents US 5,507,253 and US 8,230,827 B2 concern solutions wherein the air intake from the external environment is carried out by the same pistons that generate usable mechanical work, and thus have to rely upon air supply devices of the conventional type which may represent a non optimal choice for this type of engines. FR 2 828 711 Bl instead illustrates a solution in which part of the pistons provides a compressor unit for the intake and transfer of the airflow taken in to the cylinders where the engine pistons are located. However, even in this case the solution is poorly flexible in that the engine pistons and compressor unit pistons are part of the same carousel, which limits the movements thereof and thus limits the possibilities of adjustment thereof. Object of the invention

The object of the invention is to overcome the aforementioned technical problems.

Summary of the invention

The object of the invention is achieved by an internal combustion engine having the features forming the subject of one or more of the claims that follow, which form an integral part of the technical disclosure herein provided in relation to the invention.

In particular, the object of the invention is achieved by an internal combustion engine including:

- a motor unit including a first drum rotatable around a first axis and connected in rotation to an output shaft, said first drum including one or more cylinders having an axis parallel to said first axis, within which corresponding one or more pistons are mounted in an axially movable manner, said first drum being configured to drive said one or more pistons in rotation around said first axis along a track provided on a first plate,

a compressor unit including a second drum rotatable around a second axis and operable in rotation by means of said motor unit, said second drum including one or more cylinders having an axis parallel to said second axis and within which corresponding one or more pistons are mounted in an axially movable manner, said second drum being configured to draw said one or more pistons in rotation around said second axis along a track provided on a second plate,

- said one or more pistons of said compressor unit are configured for the intake of an airflow through an intake port and the transfer of said airflow to the motor unit by means of a transfer duct,

the engine being characterised in that the second plate is operable in rotation around an axis which is transverse to said second axis to modulate a displacement of said compressor unit (C) .

Brief description of the figures

The invention will now be described with reference to the attached figures, provided purely by way of non- limiting example, wherein:

figure 1 is a perspective view, with some components removed, of an engine according to a first embodiment of the invention,

- figure 2 is a longitudinal sectional view of the engine of figure 1,

figure 2A is a lateral non-sectional view according to arrow IIA of figure 1

- figure 3 is a view according to arrow III of figure 2,

figure 4 is a view according to arrow IV of figure 2,

- figure 5 is a perspective view of a component indicated by arrow V in figure 2,

- figure 6 includes four portions 6A, 6B, 6C, 6D, illustrating possible adjustments of the internal combustion engine, and a portion 6E illustrating the assembled casing of the engine 1,

- figure 7 is a perspective view of an internal combustion engine according to a second embodiment of the invention, and

figure 8 illustrates a perspective view of components inside the engine of figure 7.

Detailed description of preferred embodiments

The reference number 1 in figure 1 designates in its entirety an axial piston internal combustion engine according to a first preferred embodiment of the invention .

With reference to figures 1 and 2, the internal combustion engine 1 includes a casing comprising a base plate 2, a first jacket 4, a second jacket 6 and a timing plate 8 which also serves as a closure plate. In this embodiment, the plate 2, the jackets 4 and 6, and the plate 8 are substantially "8" ( "eight" ) -shaped, i.e. a bilobed shape with two circular through openings in correspondence of each of the lobes.

The components 2, 4, 6, 8, as visible in figure 2, are adjacent and coupled to each other in the indicated sequence, and thus define two substantially cylindrical cavities in correspondence of each lobe of the "8" ( "eight" ) -wise shape. A first piston carousel 10 and a second piston carousel 12 are respectively housed in the aforementioned cylindrical cavities.

The first carousel 10 defines a motor unit M of the internal combustion engine 1 while the carousel 12 defines a compressor unit C, as will result from the description that follows.

The motor unit M includes a first drum 14 having a cylindrical shape, rotatable around a first axis XI, and housed in a cavity having a complementary shape (except for radial clearances required for mounting and operation) provided in the second jacket 6.

A plurality of cylinders C14 each having an axis XC14 parallel to the axis XI and arranged angularly evenly spaced along a circumference, is provided in the first drum 14. Thus, the drum 14 is substantially shaped as a cylindrical element with a plurality of axial through holes corresponding to the cylinders C14 and a central hole 16 comprised among all cylinders C14.

However, it should be observed that the number of cylinders C14, eight in the figure, may vary as a function of the requirements, and it may be comprised between a minimum of only one cylinder and a maximum which mainly depends on the technical requirements and available maximum overall dimensions. Within each of the cylinders C14 there is mounted a piston 18 in an axially moveable fashion, to which -in turn- a first end (or head) of a connecting rod 20 is connected, whose second end (or foot) is connected to a shoe 22 slidable along a circumferential path defined by a track TM provided on a first plate 24. As visible in figure 2, the connection between the head and the foot of each connecting rod 20 and the piston 18 and the shoe 22 is preferably provided by means of spherical joints. The shoe 22 can be separate for each piston (and be shaped to form a circular crown section) or - more preferably - it can be provided as a single annular element whereon all shoes of the connecting rods 20 are fitted.

The plate 24, circular shaped, is arranged in a concentric fashion with respect to the axis XI but not necessarily coaxial. In particular, the plate 24 generally has an inclination angle a24 (figure 2) with respect to the axis XI, whose magnitude may vary from 90° up to a minimum of about 60°-70°. Taking the complementary angle a24* (see figure 2 again) as the reference angle, the complementary angle is comprised between 0 and 20°-30°. The variation of the inclination angle of the plate 24, occurs through an associated actuator unit, as described hereinafter.

To this end, in order to allow the oscillation of the plate 24, the latter is mounted through an oscillating joint 26 (preferably of the spherical type) on a tubular element 28, in turn fitted on an output shaft 30 of the motor unit M. The tubular element 28 terminates at a first end with a bell-shaped housing 28A fixed to the drum 14 and at a second end with an internal spline 28B configured for coupling with a corresponding external spline 30B on the shaft 30. This allows transmitting torque from the drum 14 to the output shaft 30.

In addition to the hub of the joint 26, the following components are mounted on the sleeve 28, all free to slide axially:

- a support plate 32, to which the plate 24 is hinged around a transverse axis Y24; as visible in the subsequent figure 2A, the support plate 32 includes two hinge members 32A, 32B in diametrically opposite position, which identify the axis Y24 and carry the plate 24; and

- a sleeve 34 abutting against the plate 32 and housed in a seat thereon, wherein furthermore a piston 36 moveable together with the sleeve 34 in a cylinder 37 (fixed to the plate 2), is interference fitted on the sleeve 34, thus defining a hydraulic/pneumatic actuator .

The aforementioned components (except for the cylinder 37) constitute a mobile unit operated by fluid (air or oil depending on the needs) through which the axial movement of the plate 24 is obtained. The sleeve 34 (alongside the piston 37 fixed thereto) and the plate are all slidable along the tubular element 28.

The output shaft 30, which is borne in rotation with respect to the base plate 2 and the head 8 through rolling bearings or sliding bearings (depending on the needs), and terminates, at the end opposite to that where the grooved profile 30B is located, with a power take-off PTO through which mechanical connection to a user is enabled.

In addition, a pinion 38 meshing with an idle wheel 40 rotatable around an axis X40 parallel with respect to the axis XI is coupled to the spline 30B (i.e. at the opposite end of the output shaft 30) . The idle wheel X40 then meshes with a second pinion 42 which is fitted on a driving shaft 44 of the compressor unit C, preferably with hollow section. Also the shaft 44 is borne in rotation with respect to the base plate and the head 8 through rolling bearings or sliding bearings (depending on the needs) .

The compressor unit C includes, similarly to the motor unit M, a second drum 46 rotatable around a second axis X2 which is the same axis around which the driving shaft 44 rotates (and also coincides with the geometric axis of the same) . The latter is connected in rotation to the drum 46 through a bell-shaped housing 48.

The axis X2 is parallel and distinct with respect to the axis XI.

The drum 46 includes a plurality of cylinders C46 each having an axis XC46 parallel to the second axis X2. Thus, the drum 46 comprises a plurality of cylinders C46 arranged along a circumference around the axis X2 and around a cylindrical through hole 50 traversed by the driving shaft 44. Thus, the drum 46 is substantially shaped as a cylindrical element with a plurality of axial through holes corresponding to the cylinders C46 and the hole C46 comprised among all cylinders C46.

Even in this case, the number of cylinders C46 may vary (eight in the figure) and it may range from a minimum of only one cylinder to a maximum which mainly depends on the construction needs and available overall dimensions. In addition, it should be observed that it is not necessary that the number of cylinders C46 be equivalent to the number of cylinders C14. This aspect shall be further addressed in the functional description of the engine.

Similarly to the drum 14, the drum 46 is rotatably mounted in a complementary-shaped cavity (except for radial clearances required for operation) obtained in the jacket 6. A piston 52 (one for each cylinder 46), to which a first end (or head) of a respective connecting rod 54, is housed - mounted axially moveable - in each cylinder C46. A second end (or foot) of each connecting rod 54 is instead connected to a shoe 56, substantially analogous to the shoe 22.

The shoe 56 is slidably mounted along the circumferential path defined by a track TC obtained on a second plate 58. The second plate 58 is mounted on an oscillating joint 60 (preferably of the spherical type) fitted on the driving shaft 44 and adapted to allow a variation of the orientation of the plate 58 with respect to the axis X2.

The plate 58 oscillates around a mobile hinge axis indicated with reference number Y58, transversal with respect to the axis X2.

The mobile hinge is defined by an axially movable support plate 62, which bears two peripheral hinge members 62A, 62B which identify the axis Y58. Thus, the plate 58 is hinged to the plate 62 at the hinge elements 62A, 62B.

In addition, the plate 58 is engaged to a pair of brackets 63 provided on the second jacket 6 substantially at the interface with the jacket 4. The two brackets 63 have a slot in which corresponding pins are engaged on the plate 58, the slot being shaped according to a curvilinear profile so as to allow the rotation of the plate 58 around the axis Y58.

As a matter of fact, it should be observed that - in particular with reference to figure 2 - the plate 58 is hinged around the axis Y58 in a substantially diametrical position, while the pins that are engaged in the slots on the brackets 63 are in a substantially chordal position (the axes are parallel to each other) . The hinge identified by the axis Y58 is defined as mobile in that the position thereof along the axis X2 is variable. As a matter of fact, the support plate 62 is part of a mobile unit which also includes a cup-like element 64 coupled to the plate 62, and a piston 66 coupled to the cup-like element 64 and mounted axially slidable along the shaft 44 (and the axis X2) .

The piston 55 is axially moveable in a fluid chamber 68 provided in a cylinder 70 fixed to the base plate 2, thus defining a hydraulic or pneumatic actuator of a servomechanism for displacing the aforementioned mobile unit along the axis and, lastly, the hinge associated to the axis Y58.

By virtue of this, the plate 58 - similarly to the plate 24 - is hinged but not necessarily coaxial to the axis X2, with respect to which it has an inclination defined by an angle β58 variable between 90° and about 60-70°. With reference to the complementary angle β58*, the latter consequently varies between 0 and 20-30°.

The slot on the hinges 63 is indispensible to allow the rotation of the plate with the following constraint conditions: the distance of the diametrical and chordal constraint points on the plate is constant, but as a function of the angle β the magnitude of components in the transverse direction transversal and parallel to the axis X2 is varied. Given that the position of the axis Y58 in the transverse direction is fixed, same case as that of the brackets 63, the only way to prevent jamming in the system due to the variation of the angle β58 is allowing relative motion between the pins of the plate and the brackets 63, which occurs due to the slots. Naturally, the slots are indispensable in cases where the aforementioned constraint arrangement of the plate 58 is adopted. Should the constraint conditions be different, the brackets 63 could even be unnecessary.

With reference to figures 3 and 4, the cylinder head 8 will now be described.

Figures 3 and 4 respectively illustrate an external and internal view of the cylinder head 8 wherein the following elements are visible:

a bean-shaped intake port IP provided in correspondence of the cavity where the compressor unit C is located,

- at least one transfer port TP (figure 4) which constitutes the outlet of at least one corresponding transfer duct TD; for this purpose, the transfer ports face both the motor unit M, and the compressor unit C, while the transfer duct TD (more than one in some embodiments) is arranged astride between the motor unit M and compressor unit C,

a bean-shaped exhaust port EP arranged in a position substantially similar to the intake port IP and in correspondence of the cavity where the motor unit M is located; for this purpose, the expression "similar position" is used to indicate the same position with respect to the reference axis (XI for the motor unit, X2 for the compressor unit) ,

- a spark plug SP with the corresponding seat arranged in proximity of the transfer ports TP on the motor unit M and in an opposite position with respect to the exhaust port EP, i.e. in an area where the combustion ignition will occur,

- the seats for the shafts 30 and 44.

Lastly, figure 5 illustrates the second jacket 6 alone. The jacket 6 is - in the illustrated embodiment - provided with a jacket for a coolant (not visible in the figure) , which gives out at a coolant inlet opening 6_IN and a coolant outlet opening 6_0UT . The cylindrical cavities whereon the previously described intake, exhaust and transfer ports IP, EP, TP as well as the spark plug SP give out, and which house the drums 14 and 46, are provided for in the jacket 6. Circular crowns of studs 74 which also traverse the first jacket 4 and the base plate 2 allowing the closure of the casing of the engine 1 are fixed in a substantially perimeter position on the jacket 6.

A counter plate 6A, whereon the hinge elements 63 are provided, is also fixed to the jacket 6.

The engine 1 operates as follows.

With reference to figures 1 to 4, two fundamental functions may be identified in the engine 1 which are assigned to the two units that constitute the latter, in particular:

- the motor unit 1 has the function of generating useful mechanical work on the output shaft 30 through the combustion of an air and fuel mixture in the cylinders in proximity of a top dead centre TDC (figure 1); in addition, the motor unit M has the function of driving the compressor unit C in rotation;

the compressor unit C has the function of intaking an airflow through the intake port IP, compressing the same in the cylinders C46 and transferring the compressed airflow to the motor unit M through the one or more transfer ducts TD (in case of several transfer ducts) .

From a kinematic point of view, the operation of each of the two units is not different from that of axial piston and swashplate hydraulic machines.

In other words, for example with reference to the motor unit M, the reciprocating motion of the pistons 18 in the cylinders 14 is obtained by operating the drum 14 in rotation around the axis XI, thus leading to a corresponding driving of an assembly of components formed by all pistons 18, the connecting rods and the shoe(s) 22 in rotation around the axis XI; thus, the latter slide along the track TM of the plate 24.

The rotation of the aforementioned assembly of elements around the axis XI imparts to the pistons 18 and connecting rods 24 a trajectory which - when the plate 24 is inclined (i.e. concentric but not coaxial) with respect to the axis XI - develops between a maximum distance and minimum distance with respect to the edge of the cylinders C14. The difference between these two distances (maximum and minimum) determines the axial stroke of the pistons 18.

The compressor unit C operates exactly identically from a kinematic point of view: driving the drum 46 in rotation by means of the driving shaft 44 causes a corresponding driving of an assembly of elements formed by the pistons 52, the connecting rods 54 and the shoe 56 in rotation around the axis X2, causing the shoe 56 to slide along the track TC of the plate 58.

Thus, the rotary motion of the carousel 12 around the axis X2 leads to a reciprocating motion of the pistons 52 in the cylinders C46 in so far as the shoes 56 travel a circular trajectory which - when the plate 58 is inclined (i.e. concentric but not coaxial) with respect to the axis X2 - has a maximum distance point and minimum distance point with respect to the drum 46 (i.e. with respect to the edge of the cylinders C46) . The difference between these distances determines the axial stroke of the pistons 52.

In both the motor M and compressor C units, the axial stroke of the pistons is lastly determined by the inclination angle of the plate 24 or 28 with respect to axes XI or X2 respectively.

The modes of variation of the inclination of the plates 24 and 58 with respect to the axes XI and X2 will now be described.

As regards the compressor unit C, the adjustment of the inclination of the plate 58 occurs through the fluid actuator formed by the piston 66 and the fluid chamber 68. Alternatively, an electromechanical positioning system may be used.

With reference to figure 6, the axial position of the piston 66 along the axis X2 may define at least three operating positions, i.e. two extreme and at least one intermediate position, which correspond to the minimum, maximum and intermediate displacement conditions of the compressor C (and equivalently to the zero, maximum and intermediate stroke of the pistons 18) .

In this regard, note the simultaneous presence - at the bottom of figures 6A-6C - of the same figure at a smaller scale indicating an operating value correlated to the displacement value.

The axial position of the piston 66 along the axis X2 unambiguously determines the inclination of the plate 58 in so far as it also determines the position of the hinge axis Y58. A variation in the position of the axis Y58 generates a rotation of the plate 58 around the axis Y63 and, thus, a variation of the inclination β58 (or β58*) of the plate 58 with respect to the axis X2 and with respect to the drum 46.

With reference to figure 6A, the minimum displacement condition of the of the compressor unit C corresponds to having the piston 66 abutting against the bottom of the cylinder 70, in an opposite position with respect to the base plate 2. This condition corresponds to the extreme position of the piston 66 opposite to that illustrated in figure 2.

In this condition, the axial stroke of the pistons 52 is nil, and thus the airflow intaken from the external environment and transferred to the motor unit M is zero. This is due to the fact that the track TC on which the shoes 56 (or the shoe 56) slide has a constant distance with respect to the edge of the cylinders C46. In addition, in this position the plate 58 is coaxial and concentric with respect to the axis X2.

Figure 6B illustrates an intermediate displacement condition, equivalent to 50% of the maximum displacement in this case, and it corresponds to a substantially intermediate position of the piston 66 between the two end stops provided by the bottom of the cylinder 70 on one side and by the base plate 2 on the other .

Figure 6C instead illustrates a condition of maximum displacement of the compressor unit C, which corresponds to the conditions of maximum axial stroke of the pistons 52, maximum inclination of the plate 58 with respect to the axis XI, and it also corresponds to the extreme position of the piston 66 illustrated in figure 2 (abutment against the base plate 2) .

The operation of the piston 66 through a working fluid (oil or compressed air) , allows driving the plate 58 in rotation around the axis Y63 (thus, the rotation around the axis Y58 occurs due to the double hinge which constitutes the constraint of the plate 58) so as to vary the displacement of the compressor unit C and thus vary the airflow taken in and transferred to the motor unit M. In addition, it should be observed that the movement of the piston 66 actually allows defining an infinite number of operating positions between the two extreme positions, the adjustment being of the continuous type.

With reference to figure 6D, the motor unit M is characterised - on the contrary - by the presence of two separate and independent degrees of freedom. These degrees of freedom correspond to the axial position of the plate 24 along the axis XI (degree of freedom X24 in figure 6D) and the inclination angle a24* of the plate 24 (thus also defining the angle a24) .

The variation of angle a24* is achieved through a linear actuator whose ends are hinged to the periphery of the support plate 32 and the plate 24; in figure 6D, the actuator 24 is schematically represented using a line with reference ACT. Thus, the operation of the linear actuator determines the rotation of the plate 24 around the axis Y24.

Thus, this allows varying the displacement of the motor unit M, i.e. the stroke of the pistons 18, exactly identically to the methods described regarding the compressor unit C.

As regards the axial position of the plate 24, it is varied by operating the support plate 32 in translation along the axis XI. This occurs - entirely identically to the steps described regarding the compressor unit C - by operating the piston 36 by means of the pressurised fluid conveyed in the cylinder 37. This causes the movement of the mobile unit including the sleeve 34 and the support plate 32 along the axis XI, thus determining a variation of the axial position of the carousel 10, drum 14 excluded.

The axial position X24 of the plate with respect to the drum 14 (which, as mentioned, remains axially fixed) determines the maximum and minimum compression ratio of the motor unit M. Defining the volumetric compression ratio as the ratio between the maximum volume and the minimum volume of the combustion chamber during the movement of the piston 18, the compression ratio of the motor unit M shall be minimum when the distance of the support plate 32 is maximum with respect to the drum 14, whereas the compression ratio shall be maximum when the distance is minimum. In addition, it should be observed that the variation of the stroke/displacement of the motor unit M (same case applying to the compression unit C) is already capable of affecting the volumetric compression ratio. In particular, every time the stroke of the pistons 18 is nullified, the volumetric compression ratio takes a unitary value, moving to a maximum value when the stroke is brought to the maximum value thereof.

On the contrary, the barometric compression ratio, i.e. the ratio between the maximum and minimum pressure of the fluid in the combustion chamber, varies considerably as a function of the axial position of the plate 24.

In addition, each of the two plates 24, 58 is can be adjusted in angular position with respect to the stator of the internal combustion engine 1, i.e. with respect to the assembly formed by the plate 2, the jackets 4 and 6 and the cylinder head 8. For this purpose, with reference to figure 6E, as regards the plate 24, a fluid or electromechanical actuator A24 having an end fixed to the external of the casing of the engine (on the jacket 4 by way of example in this case) and another end fixed to a stud 24S integrally joined or connected to the plate 24, can be used.

An operating cycle of the internal combustion engine 1 is characterised by the simultaneous execution of an operating cycle of the motor unit M and an operating cycle of the compressor unit C.

Each of the aforementioned operating cycles provides for two strokes of the pistons 18 and 52 for each cycle. This implies that the operation of the motor unit M can be outlined as that of a two-stroke engine. With reference to figures 3, 4 and 6E, the step of intaking air from the external environment is carried out by the compressor unit C through an intake runner IR (fixed to the timing plate 8) and the intake port IP. As observable in figure 3, the width of the intake port is such to intercept, in the embodiment subject of the figures, two pistons 52. The pistons 52 which are located at the port IP are positioned slightly beyond the corresponding top dead centre.

The airflow intake occurs thanks to the descent of the pistons 52 towards the corresponding bottom dead centre in the cylinders C46 and proceeds in the direction of rotation of the compressor unit C which is indicated with reference 9_C in figure 3 and it rotates clockwise. In case of spark ignition engines, fuel is introduced simultaneously with air intake by the pistons 52, through one or more injectors facing inside the runner IR.

In case of compression ignition engines, fuel is introduced through one or more injectors whose geometric arrangement is such to arrange them at precise stages of the operating cycle. This allows introducing fuel in a fractionated manner at various points of the cycle with effects similar to that of the multiple injections on diesel-fuelled compression ignition engines with common rail systems.

The ascent of the pistons 52 towards the top dead centre terminates with the pistons 52 facing the transfer port (or transfer ports if more than one) TP, which occurs substantially at the top dead centre. The compressed air-fuel mixture in the cylinders C46 is transferred to the motor unit M through the transfer port and the transfer ducts, then the pistons 52 once again face the intake port IP and the cycle resumes as described previously. In case of compression ignition engines, at least one first fuel injection (pilot injection) may once again occur at the compressor unit, before transferring the air to the motor unit. This may be attained by arranging an injector slightly downstream of the transfer port(s) .

The air-fuel mixture transferred from the compressor unit C to the motor unit M enters into the cylinders C14 whose pistons 18 have just completed an exhaust phase and are about to reach the top dead centre TDC. Thus, the transfer of the airflow occurs in proximity of the top dead centre, then after a further brief phase of compressing the air and fuel mixture - the latter is ignited through the spark plug SP. In case of compression ignition engines, the amount of fuel still to be injected may be introduced during the residual compression stroke (pre-inj ection) , approximately at the top dead centre (main injection) and downstream of the top dead centre (so-called after and post injections, the latter with an extremely delayed timing) . Each of these injections may be carried out by a different injector mounted on a timing plate 8 and positioned so as to have a well defined timing with respect to the operating cycle.

Downstream of the ignition of the air-fuel mixture, each piston (in succession) is pushed towards the bottom dead centre by the expansion of the gases in the combustion chamber, thus generating useful mechanical work on the shaft 30 along an angular range of about 180° comprised between the spark plug SP (in spark ignition engines) and the beginning of the exhaust port EP. The rotation of the carousel 10 is indicated with reference Θ_Μ in figure 3 and it rotates clockwise .

For better reference, figures 3 and 4 show all the angular ranges corresponding to the phases of the engine 1 as follows:

INT: intake phase

- COMP: compression phase (in the compression unit C) ; a first injector for compression ignition engines may be positioned here (pilot inj ection)

- COMP': compression phase prior to ignition (in the motor unit M ) ; a second (and possibly a third) injector for compression ignition engines may be positioned here (pre-inj ection, if necessary, and main injection)

- TRANSF: transfer phase

- POW: combustion and expansion phases (generation of duty cycle); further one or two injectors - for compression ignition engines - may be positioned here for the execution of the after and post injections

- EXH : exhaust phase

A minor share of useful mechanical work generated on the shaft 30 is absorbed by the compressor unit C to drive the compressor unit C in rotation through the cascaded gears 38, 40, 42.

After the completion of the useful mechanical work generation phase, the pistons 18 face the exhaust port EP in succession for the discharge of burnt gases, then the cycle of the motor unit M resumes identically, obviously simultaneously with the compressor unit C.

Furthermore, it should be observed that each complete revolution of the carousels 10, 12 around the axes XI, X2 corresponds to an operating cycle performed by each of the pistons 18, 52, hence the number of operating cycles carried out in the motor unit and compressor unit per revolution corresponds to the number of respective pistons.

In this specific case, each rotation covers eight operating cycles on the side of the motor unit and eight operating cycles on the compressor unit side.

The adjustment of the engine 1 occurs according to the method to be described hereinafter.

The airflow intaken by the engine 1, which coincides with the air flow intaken by the compressor unit C, is regulated by modulating the displacement of the compressor unit C per rotation, i.e. via the axial movement of the piston 66 which determines, as described previously, a variation of the inclination angle of the plate 58 with respect to the axis X2. This represents a considerable advantage with respect to axial piston engines of the type mentioned at the beginning of the present description, which do not allow this regulation in any manner whatsoever.

Furthermore: jointly exploiting the possibility of modulating the displacement of the compressor unit C and the motor unit M also allows attaining a supercharging of the engine 1 without requiring an external supercharger unit such as a centrifugal turbocharger or a volumetric compressor.

This is due to the fact that the displacement of the motor unit M can be modulated so that it is lower with respect to the displacement of the compressor unit C.

Thus, when transferring the fluid from the compressor unit C to the motor unit M, the gas will be already further compressed during the actual transfer phase due to the displacement difference between the two machines. Modulating the displacement of the compressor unit C with respect to the displacement of the motor unit M also allows varying the boost pressure of the engine 1 dynamically. Also this technical effect represents a considerable advantage with respect to the prior art axial piston engines mentioned at the beginning of the description.

As known to a man skilled in the art, both the air flow variation and the supercharging of the internal combustion engine 1 are actions that allow to meet the torque request by the user.

However, the adjustment possibilities may also be exploited to optimise the performance of the engine 1 depending on the operating conditions and/or the type of fuel used.

For example, the possibility of adjusting the compression ratio and the maximum pressure in the combustion chamber allows optimising the operation of the engine under any conditions and even depending on the type of fuel used and/or - in case of spark ignition operation of the engine - depending on the spark advance that is used.

Furthermore, the possibility of adjusting the compression ratio offers an additional degree of freedom on which one may act to minimise the pollutant emissions of the engine.

The possibility of varying the angular position of the plates 24 and 58 with respect to the stator of the engine 1 thus imparting a rotation around the axis XI, X2 (respectively) thereto, further allows obtaining additional results of technical importance.

These adjustments generally modify the timing of the operating cycles, in that the following are varied:

- the transfer conditions (pressure firstly) of the engine 1 (plate 58), in so far as the pistons 52 will be positioned at the intake port IP in a position more or less proximal to one of the two dead centres with respect to the standard timing, and

- the spark advance of the air-fuel mixture (plate 24) for spark ignition engines, and the injection timing for compression ignition engines. As a matter of fact, the man skilled in the art will observe that the timing of the bottom and top dead centres of each piston with respect to the timing ports (intake, exhaust and transfer) of the engine is determined by the angular position of the two main points (maximum and minimum) of the circular trajectory identified tracks TM and TC with respect to the plate 8.

Should this position be varied angularly, i.e. along the reference coordinate for the operating cycle, it is clear that it will also vary the timing of the dead centres with respect to the operating cycle.

In addition, the fact that the motor unit M and the compressor unit C are associated to the rotation axes XI, X2 parallel and distinct with respect to each other, as well as to two separate piston carousels 10, 12, allows fully separating the operation of one with respect to the other, thus fully attaining the flexibility absent in the prior art solutions mentioned at the beginning of the description. The operation of the motor and compressor units is separated at this point to the extent of obtaining perfectly operating engines 1 even in cases where the number of cylinders between the units is different, or when the two units do not rotate synchronously, or both. For example, this implies that the airflow taken in can be modulated even by varying the rotational speed of the carousel 12 of the compressor unit independently and separately with respect to the rotation of the carousel 10, thus adding an additional degree of freedom. For example, if the rotational speed of the carousel 12 is doubled with respect to that of the carousel 10, a double airflow - being the displacement equal - will be taken in and transferred to the motor unit.

Thus, there are several possibilities of adjusting the engine 1 and they derive from the possibility of combining the actions on the various degrees of freedom (or control axes) described above, in any manner.

For example, together with the modulation of the pressure at the combustion top dead centre via an action on the degree of freedom X24, it is possible to modulate also the torque generated by the engine by modulating the displacement of the motor unit M (degree of freedom a24 or a24*), to obtain, being the compression ratio equal, a higher or lower torque.

The highest torque values correspond to the highest stroke values of the pistons 18, i.e. displacement values.

In addition, the aforementioned operations may be combined differently with the aim of obtaining a constant power by modulating the shaft torque 30.

The main advantages of the architecture of the internal combustion engine 1 definitely include the ease of adjusting parameters such as the displacement and compression ratio, which are generally not adjustable in crankshaft alternative internal combustion engines. This allows obtaining maximum performance from all rotation regimes, or maximum power, or optimal operating temperatures depending on the operating conditions. In addition, combustion can be optimised (even depending on the type of fuel) thus minimising the pollutant emissions from the exhaust system.

As described above, the engine may be operated with a flat torque curve regardless of the rotation regime due to the possibility of modulating the displacement (and possibly the compression ratio) of the motor unit M.

Lastly, with reference to figures 7 and 8, a second embodiment of the engine 1 is indicated with reference number 100 and it is illustrated in an assembled external view (figure 7) and a view of some internal components (figure 8) .

The difference between the engine 100 and the engine 1 essentially lies in the fact that the stator includes two separate casings, one - 100M - housing the motor unit M, the other - lOOC - housing the compressor unit C.

The casings 100M and lOOC are mutually interfaced at a timing plate 100P, to which they are fixed on opposite sides thereof. The plate 100P bears the ports IP, EP, TP and the transfer duct/s TD.

Both casings 100M and lOOC include a base plate 102M, 102C, a first jacket 104M, 104C which serves the same purpose as the jacket 4 (plates housing), a second jacket 106M, 106C which serves the same purpose as the jacket 6 (drums housing) and lastly, it is closed by the timing plate 100P.

A first and a second carousel 110, 112 which identify the motor unit M and the compressor unit C of the engine 100 are arranged in the engine 100. The carousel 110 includes a drum (not visible in the figures) rotatable around an axis X100 and it is provided with one or more cylinders with axis parallel to the axis X100 in which corresponding pistons 118 are mounted in an axially movable manner.

A corresponding first end (head) of a connecting rod 120, whose second end (foot) is fixed to a shoe moveable along a circular trajectory on a track obtained on a first plate 124, is fixed to each piston 118.

The plate 124 fitted on an output shaft 130 through an oscillating joint 126 and it is also hinged to a support plate 128 around an axis Y124 transversal with respect to the axis X100. In addition, the drum of the motor unit is connected to the output shaft 130 in rotation, for example by means of a bell-shaped housing 129 similar to the bell-shaped housing 28B.

The support plate 128 terminates with a hub on which a threaded collar 132, which is axially constrained to the plate 128, is freely rotatably mounted and it is engaged in a corresponding threaded hole on the base plate 102M. The rotation of the threaded collar 132 allows varying the axial position along the axis X100 of the support plate 128 and plate 124.

The articulation of the plate 124 with respect to the support plate 128 also allows varying the inclination angle of the plate 124 with respect to the axis X100 (the plate 124 is concentric but not necessarily coaxial to the axis X100) , thus modulating the displacement of the axial stroke of the pistons 118.

The output shaft 130 is connected, by means of cascaded gears 134, to a driving shaft 144 of the second carousel 112. A second drum (not visible in the figure) bearing a plurality of cylinders having an axis parallel to the axis X200 and in which corresponding pistons 152 are axially moveable, is rotatably connected to the driving shaft 144 by means of a bell- shaped housing 145. A first end (head) of a connecting rod 154, whose second end (foot) is fixed to a shoe which is slidably engaged in a circular track obtained on a second plate 158, is connected to each piston 130.

The plate 158 is articulated around an axis Y158, transversal with respect to the axis X200, to a support plate 160 fitted on the driving shaft 144 through an oscillating joint (not visible in the figure), but not connected to the shaft 144 in rotation.

The engine 100 has the same degrees of freedom as the engine 1 and in particular:

- the plate 124 of the first carousel 110 can be operated in rotation around the axis Y124 to modulate the displacement of the motor unit M (i.e. the stroke of the pistons 118),

- the plate 124 can be moved axially along the axis X100 so as to vary the compression ratio of the motor unit M,

- the plate 124 has a variable angular position with respect to the jacket 104M, for example by operating on a stud L provided integrally joined on the support plate 128, so as to vary the timing of the top and bottom dead centres of the pistons 118 with respect to the timing ports of the engine 100, and thus vary the spark advance,

- the plate 158 can be operated around the axis Y158 in rotation so as to vary the displacement of the compressor unit C (i.e. the stroke of the pistons 152) .

The engine 100 also operates identically to the engine 1, in particular the air intake from the external environment occurs through an intake port IP provided on the timing plate 100P and the transfer of compressed gases to the motor unit M occurs through a transfer duct not visible in the figure.

In addition, all adjustment capabilities and advantages described above remain identical.

Obviously, the construction details and the embodiments may widely vary with respect to what has been described and illustrated, without departing from the scope of protection of the present invention as defined by the attached claims.

For example, the mechanical transmission between the shafts 30 and 44 (130 and 144) may provide for a belt transmission or chain transmission instead of gear wheels. In addition, variants of the engine 1; 100 wherein the plate 24, 124 can be adjusted only partly with respect to the aforementioned degrees of freedom may be provided for, for example only regarding inclination with respect to the axis XI, X100 or only in the axial position. Generally, it is preferable not to eliminate the possibility of adjusting the angular position with respect to the stator, in that this would lead to losing the possibility of varying the spark advance. However, yet further low cost variants may be envisaged wherein the variation of the spark advance is omitted while maintaining at least one of the aforementioned degrees of freedom.

In addition, although the figures illustrate a version of the spark ignition internal combustion engine, the engine may be adapted to a compression ignition engine for example by replacing the spark plug SP with a fuel injector.

Claims

1. An internal combustion engine (1; 100) including :

- a motor unit (M) including a first drum (14) rotatable around a first axis (XI; X100) and connected in rotation to an output shaft (30; 130), said first drum (14) including one or more cylinders (C14) having an axis (XC14) parallel to said first axis (XI; X100) and inside of which corresponding one or more pistons (18; 118) are mounted in an axially movable manner, said first drum (14) being configured to draw said one or more pistons (18; 118) in rotation around said first axis (XI; X100) along a track (TM) provided on a first plate (24; 124),

- a compressor unit (C) including a second drum (46) rotatable around a second axis (X2; X200) and operable in rotation by means of said motor unit (M) , said second drum (46) including one or more cylinders (C46) having an axis (XC46) parallel to said second axis (X2; X200) and inside of which corresponding one or more pistons (46; 146) are mounted in an axially movable manner, said second drum (46) being configured to draw said one or more pistons (46; 146) in rotation around said second axis (X2; X200) along a track (TC) provided on a second plate (58; 158),

said one or more pistons (52; 152) of said compressor unit (C) are configured for the intake of an air flow through an intake port (IP) and the transfer of said air flow to the motor unit (M) by means of a transfer duct (TD) ,

the engine (1; 100) being characterized in that the second plate (58; 158) is operable in rotation around an axis which is transverse to said second axis (X2) to modulate a displacement of said compressor unit (C) .

2. The internal combustion engine (1; 100) according to Claim 1, wherein said first and second axis (XI, X2; X100, X200) are parallel to one another and distinct.

3. The internal combustion engine (1; 100) according to Claim 1 or Claim 2, wherein furthermore said first plate (24; 124) is adjustable via at least one of:

- a rotation around an axis (Y24) transversal to said first axis so as to vary the orientation of said first plate (24; 124) with respect to said first axis (XI) and modulate a displacement of said motor unit (M) , and

- a translation along said first axis (XI; X100) so as to vary a distance of said first plate (24; 124) with respect to said first drum (14) and modulate a compression ratio of said motor unit (M) .

4 . The internal combustion engine (1; 100) according to any of the previous claims, including a stator (2, 4, 6, 8, 100M, lOOC) housing said motor unit (M) and said compressor unit (C) .

5. The internal combustion engine (1) according to claim 4, wherein said stator (2, 4, 6, 8) houses both said motor unit (M) and compressor unit (C) in a same casing .

6. The internal combustion engine (100) according to Claim 4, wherein said stator includes two distinct casings, one (100M) housing said motor unit (M) , the other (lOOC) housing said compressor unit (C) .

7 . The internal combustion engine (1) according to Claim 5, wherein said stator includes a base plate (2), a first jacket (4) in correspondence of which said first (24) and second (58) plates are housed, a second jacket (6) in correspondence of which said first (14) and second (46) drums are housed, and a timing plate (8) whereon said intake port (IP), said one or more transfer ports (TP) and said exhaust port (EP) are provided .

8. The internal combustion engine (100) according to Claim 6, wherein each casing of said stator includes a base plate (102M, 102C) , a first jacket (104M, 104C) in correspondence of which the first (124) or the second (158) plates are correspondingly housed, a second jacket (6) inside of which said first (14) or second (46) drums are correspondingly housed,

wherein the two casings are connected to one another on opposite sides of a timing plate (100P) whereon said intake port (IP), said one or more transfer ports (TP) and said exhaust port (EP) are provided .

9. The internal combustion engine (1; 100) according to any of Claims 4 to 8, wherein said first plate (24; 124) is positionable in an angularly variable manner with respect to said stator.

10. The internal combustion engine (1; 100) according to any of Claims 4 to 9, wherein said second plate (58; 158) is positionable in an angularly variable manner with respect to said stator.