A device for converting a rectilinear reciprocating motion into a rotational motion Technical Field The present invention relates to a device for converting a rectilinear reciprocating motion into a rotational motion and vice versa, which may be used in place of the classical crank mechanism exerting a rotary push action. Specifically, the present invention concerns the typology of devices applicable to that end, which are based on the geometrical principle of Cardano, and which are intended to solve-among other problems-the drawback of lateral forces induced by the pistons on the corresponding cylinder lateral walls. Although the application of this geometrical principle, e. g. to volumetric reciprocating motors, is already known since a long time, the devices which have been realized up to now have substantial drawbacks, which-as explained below-make their operation liable to failure and breaking, whereas in other cases, the solutions adopted are structurally too complex, and notwithstanding the fact that they are described in some patent documents, they are practically not realizable.

Already at this point of the description, the fact is emphasized that the device of the present invention may be applied to volumetric and reciprocating internal combustion engines, or to compressors, although the underlying principle is very general and may include any application involving the conversion of these two kinds of motions.

Background Art Even today, when dealing with the problem of the conversion of a rotary motion into a rectilinear reciprocating motion, and vice versa, and even in the context of advanced technologies, the conventional connecting rod-and-crank mechanism (of Fig. 1) is used, notwithstanding its numerous and well-known disadvantages

(unbalance, lateral thrust on the piston, a. s. o.). Actually, a principle of the known art which would brilliantly solve the problems of this conventional mechanism, is that shown in Fig. 2. By comparing the conventional mechanism (Fig. 1) with that of Fig. 2, it may be noted that when the crank 01-03 of the conventional mechanism is split in two identical segments 02-03 and 01-02, and when opposite rotational movements are imparted to these segments, with one rotational movement being two times faster than the other, the point indicated by 03 moves along a rectilinear path.

Further, it is known that this constraint in the movement of these two segments is obtainable through the use of a gearing (see Figs. 3,4,5, and 6).

As shown in Fig. 3, an example is given by a toothed wheel (or gearwheel) 6, having an internal toothing with a pitch circle diameter PRC, which is stationary on a plane, and which engages a gearwheel 16 with external toothing and with a pitch circle diameter PRS = PRC/2. If the point 02 (see Fig. 4) is rotated around the point 01 by an angle b, the gearwheel 16 rotates by an opposite angle, equal to 2b, around the point 02. The point 03, which was the original tangential point between the pitch circles, will have shifted exactly along the axis X.

A further example is provided by the gearing shown in Fig. 5, wherein a gearwheel 6, which is supposed to be stationary on the plane and which has a pitch circle diameter PRC, imposes a rotational movement to the gearwheel 16 of pitch circle diameter PRS, through the intermediate gearwheel 13, the latter having a pitch circle diameter PR. A crank 03-02, indicated by the reference number 10, is integral with the gearwheel 16, and has a length D equal to the distance 02-01. If the ratio between the number of teeth of the gearwheel 16, and those of the gearwheel 6, is equal to 1: 2, then, by imposing a rotation to the centers OR and 02 (see Fig. 6), corresponding to a certain angle b around 01, the crank 10 will rotate around 02 by an angle 2b which is twice as large, and which has the opposite sign. In this case too, the point 03 will move exactly along the line of the axis X.

Under the point of view of its practical applications, the system illustrated in Fig. 3

is more interesting. In fact, as compared to the kinematics shown in Fig. 5, it has the advantage of having: a) a gearing based on the mutual engagement between a gearwheel with internal toothing and a gearwheel with external toothing, so that the number of simultaneously engaging teeth is much higher, and greater loads can thereby be transmitted for the same size of the toothing, b) a lesser number of components making up the mechanism ; c) the possibility of handling also small strokes, by using gearwheels having nonetheless appreciable dimensions (this corresponds to the overwhelming majority of applications).

The conventional crank thrust mechanism, which is usually employed in reciprocating machines, has a number of drawbacks and is subject to many restrictions (limitations). First of all, the lateral thrust exerted on the piston because of the inclination of the connecting rod, entails relevant organic losses (leaks), and an increased wear of the cylinder-piston interface. Therefore, there arises the need to ensure a good lubrication in order to avoid seizure. Particularly in two-stroke engines, it is required to mix to the fuel a conspicuous amount of oil (about 2%), which, when it is burned, increases the polluting emissions. The ordinary crank mechanism is also cumbersome in the direction of the cylinder axis. In fact, in order to limit the lateral thrust on the piston, the connecting rod length (l, Fig. 1) is never less than 3,5 times the radius (2D) of the crank. In the crank mechanism of Fig. 2, on the other hand, the length of the corresponding segment (which is an integral part of the"plunger 11"), may be reduced to values equal to the stroke (4D), plus a minimal length, in order to prevent the piston from hitting against the crank mechanism itself, in the BDC (bottom dead center). This disadvantage of the classical crank mechanism is particularly relevant for Diesel large-stroke and two-stroke motors typical of naval applications.

A further limitation of the classical crank mechanism is that the law of motion of the

piston is not perfectly sinusoidal, but includes higher-order harmonics, thereby giving rise to balancing difficulties. Said harmonics, including the first one, cannot be simply balanced by the use of counterweights, but require use of counter-rotating shafts. The crank mechanism shown in Fig. 2, presents only the first harmonic, which however may be balanced simply by counterweighing the movable parts.

Referring now to the non-classical crank mechanisms, which are based on the above mentioned principle (Fig. 2-6), several techniques have been developed in order to put into practice the kinematics of Figs. 3 and Fig. 5. However, in practice they have not been successful, because in the case of the mechanism shown in Fig. 3 they propose technical solutions with profound inconsistencies, which are prejudicial for correct operation, whereas for the mechanism of Fig. 5, the kinematics itself imposes a constructive complexity which discourages its use.

In the following, a brief review of these techniques is presented.

US Patent N. 2. 271, 766 of February, 3, 1942. of H. A. Huebotter (see Figs. 7 and 8 of the present application) For clarity, it is practical to define as"planetary gear"the component of axis 02 and comprising the (auxiliary crank) pin of axis 03, to which the piston or"plunger"11 (see Fig. 2) is directly connected, and to define further as"rotor"the component of axis 01, which contains one or more supports for the rotation of one or more planetary gears.

The mechanism proposed by H. A. Huebotter in 1942, see Fig. 7, whilst presenting a correct construction under the point of view of its kinematics, has a serious constructional drawback, which prevents its correct operation when a user U is connected thereto.

In fact, when analyzing this mechanism it can be noted that the bearings B1 and B2 are the supports of the planetary gear (S); the loads (forces) transmitted by the piston, are transferred to these supports through the planetary gear. These loads, due to the symmetry of the system-when no user is connected-, are equal on B1 and on B2,

and therefore also the useful torque generated by them is the same. The system is in perfect equilibrium.

When a user U is connected to the system, thus applying a braking torque to the left- side rotor, the useful torque on the right side will instantly prevail over the resulting torque on the left side. In this condition, the system-in order to reach a new equilibrium condition-reacts by transferring a couple, equal to the difference between the torque on the right and on the left side, to the only component connecting both rotors 9 to each other, that is, to the planetary gear S. This couple will substantially give rise to a transfer of forces tangential to the circular trajectories of the supports B 1 and B2, from the right to the left, and will act as a tilting moment on the constraints through which the planetary gear is connected to the rotors 9, that is, on the bearings or bushings B 1 and B2.

This kind of load is proportional to the braking moment applied to the left side rotor 9 by the user U, and it constitutes an anomalous load on the bushings or bearings; therefore, under these conditions the system would almost immediately"collapse".

This reasoning may be applied both to a motor (e. g. an internal combustion engine), and to a machine which is driven by a motor, e. g. a compressor; in fact, for a driven machine the user U simply becomes a motor, and the load analysis will remain valid if the signs of the forces are suitably changed.

Therefore, the planetary gear S is always subject to a tilting torque, although with an opposite sign. The same critical reasoning applies to the other system proposed by H. A. Huebotter, in the same patent, that is, to the embodiment with 4 pistons, which is obtained by connecting in series two of the above described mechanisms (see Fig.

8). In the latter embodiment, that part of the mechanism which is connected to the cylinders 3 and 4, is in the same condition as the system of Fig. 7, and therefore has the same drawback, while the planetary gear associated to the cylinders 1 and 2, is subject-in addition to the tilting moment which naturally arises in a twin cylinder engine-, to the transmission to the power take-off of the torque generated by the

cylinders 3 and 4.

Patent DE 875110, filed on April, 30, 1953 bv Harald Schulze, Bochum (not schematicallv illustrated in the Figs. of the present application) In 1953 the patent application DE 875,110 suggests to use a mechanism for a radial 4-cylinder motor, whose connecting rods are all connected to the same planetary gear assembly, and the latter is provided in this case with two crank pins shifted by 180° with respect to the axis of the planetary gear. Disregarding the fact that the planetary gear is subjected to the forces transmitted by four pistons instead of two, this solution is substantially identical to that proposed by H. A. Huebotter, and consequently the same reasoning applies.

US Patent 3. 626, 786 issued December. 14* 1971. to Haruo Kinoshita et al. (see Fig. 9 of the present application) This US Patent N. 3,626, 786 of 1970 proposes to use a crank mechanism of the kind shown in Fig. 9. This solution uses a pin 2 which is press-fitted inside and between two rotors 9a and 9b, and a planetary gear assembly (consisting of the integrally formed pin 1 and gearwheel 16), which rotates thereon. According to this architecture, the crank pin 1 must have a sufficiently large diameter in order to entirely contain the pin 2 and its bearing 8, shifted by a distance equal to 1/4 of the stroke with respect to the center of the crank pin 1.

The power is taken from the shaft of one of the two rotors, as for the cases analyzed above.

The pin 2 must support the planetary gear, it must coordinate the movements of both rotors, and it must transmit the loads from one rotor to the other, while maintaining at the same time the parallelism with regard to the motor principal axis 01 (a necessary condition for the correct operation of the crank pin bearing, and the pin bearing or planetary gear bearing).

This condition is satisfied only if the torsional angle, which manifests itself during operation between the two rotors, is extremely small. This angle is essentially due to

the flexional and torsional deformation of the pin 2 ; therefore, it is required to choose an appropriate size for the latter pin, even if this influences the sizing of the crank pin 1 and of the rotors 9a and 9b, when said pin reaches certain diameter values; thereby, due to weight and size increases, this system is no more advantageous (competitive) with respect to a mechanism based on the ordinary crank mechanism.

Note that (see Fig. 9), in order to allow the passage of the planetary gear pin 2, with diameter d, it is necessary to use for the crank pin 1, a diameter value P equal to: P = 2C/4 +dB + 2s = C/2 + dB + 2s, where C is the piston stroke, dB the diameter of the bearing of the pin of planetary gear assembly, and s is the thickness of the crank pin 1 which delimits (covers) the bushing. Obviously, if d becomes very large, the diameter P becomes excessively large.

US Patent N. 3. 791. 227 of February. 12. 1974 to Myron E. Cherry (not illustrated in the drawings of the present application) Although this patent is concerned with the solution of balancing problems, it suggests a mechanism similar to that proposed by H. A. Huebotter in 1942 (Fig. 7) and for this reason the same critical arguments apply.

DE 44 31 726 ail, of September, 6, 1994 (Hans Gerhards) (see Fig. 10 of the present application) The mechanism suggested by H. Gerhards (Fig. 10), notwithstanding the fact that it is provided with a synchronization shaft, does not solve the problem of the tilting moment acting on the planetary gear, because it does not ensure a perfect alignment of the two supports B 1 and B2 during operation. The reason for this misalignment is that a couple of meshing gears must have a play (clearance) in order to function properly.

The ideal motion transmission law of two meshing gearwheels, in the absence of a play, is: Ol= s-02, where Ol and 02 are the reference angles defining the angular position of the couple of gearwheels, and s is the transmission ratio. The presence of a play (clearance) introduces a deviation of the actual angular positions of the

gearwheels with respect to the ideal ones given by the preceding formula; this deviation being proportional to the play between the gearwheels.

When asking why the existence of a play between the gearwheels is the cause of improper functioning of the device of DE 44 31 726 A1, two main reasons may be found: - the fact that the intermediate rotor (9b, Fig. 10) between two consecutive cylinders is integrally formed and not formed by two independent sub-units, each having a gearwheel used to transmit the motion to the transmission shaft; - the fact that power is taken from the last rotor (9c) and not from the synchronization shaft.

The first point may be clarified (Fig. 10) by analyzing the proposed schematic assembly, and considering that during motor operation the piston PI must be in the passive phase (absorption of energy from the transmission shaft) when the cylinder P2 is in the active phase (energy transfer to the synchronization shaft). In the following, Mpl denotes the motor torque (or moment) produced by the cylinder PI, and Mp2 the motor torque (moment) produced by the cylinder P2; then, according to the preceding assumption we may take Mpl < 0, Mp2 > 0, and Mpi + MP2 > 0 because the overall motor moment must be positive.

In this situation, the moment transmitted by the gearwheel 15a to the gearwheel 14a will be: Mpl/2 < 0 ; therefore, the gearwheel 14a will drag ("push") the gearwheel 15a, and if the rotation directions are those indicated in the cross-section A-A', the couple of gearwheels will recover (eliminate) all the play (clearance) to the right of the engaging tooth (X) of the gearwheel 14a.

Analogously, the moment or torque transmitted by the gearwheel 15b to the gearwheel 14b will be: (MPi'i+ MP2)/2 > 0; therefore, the gearwheel 14b will be dragged ("pushed") by the gearwheel 15b; the couple of gearwheels will thus recover all the play (clearance) to the left of the engaging tooth (Y) of the gearwheel 14b (cross-section B-B').

Since the teeth (X) and (Y) are aligned to each other and rigidly connected to the synchronization shaft, this difference in play recovery between the gearwheels 14a/15a on one hand, and 14b/lSb on the other hand, will result in a different angular position of the rotor 9a, integral with the gearwheel 15a (angle 0 + y, cross-section A-A'), with respect to the rotor 9b, integral with the gearwheel 15b (angle 0, cross- section B-B'). This angular difference will induce a misalignment of the planetary gear supports B I and B2, which, in spite of its smallness, of the order of some tenths of a millimeter, will prevent the proper operation of the bearings, which at most can endure misalignments of some thousandths of a millimeter.

An analogous problem manifests itself due to the presence of the power take-off on one end-side-rotor. In fact, considering the rotor 9c from which the power is drawn, the moment transmitted to and by the transmission shaft (assembly 15c/14c in Fig.

10) is : Mi5c/i4o = M t-Mp2/2, where Mise/140 is the couple mutually transmitted by the gearwheels 15c/14c, and Mt is the total motor moment of all cylinders. For the fellow rotor (assembly 15b/14b in Fig. 10) this moment is equal to: Ml5b/14b = (Mpl + Mp2)/2, where Mlsbxl4bis the couple transmitted mutually by the gearwheels 15b/14b.

Due to the intrinsic properties of operation of reciprocating engines or machines, these moments are necessarily different, and when the signs are different, a different and opposite recovery of the play between the gearwheels 14b/15b and the gearwheels 15c/14c occurs ; thus the same drawback of the preceding case will be encountered.

DE 36 04 254 Al of February. 11. 1986 fTRAN. Toan Dat) This patent document deals with mechanisms based on the principle of Fig. 5, which make use of a gearing assembly with external toothing. Although this patent document proposes in some cases correct configurations for the practical use of the illustrated kinematics, in other cases it does not do so, particularly when two or more series-connected mechanisms are to be realized. Actually, in claim 9 of this

document, series-connected mechanisms are proposed, wherein their crank pin is so large that a pin can be made to pass therethrough, and can be press-fitted in two rotors facing each other, whereby two rotors of the same planetary gear become integral with each other. This technique gives rise to the same problems of the patent N. 3,626,786 of December, 14,1971, issued to Hauro Kinoshita, and therefore the conclusions drawn above from the critical review of this last patent are equally valid in this case. It should be noted that the mechanisms of DE 3, 604, 254 are quite difficult to realize, due to the elevated number of their components.

Disclosure of Invention An object of the present invention is to correctly apply the principle shown in Figs. 2 to 6, so as to eliminate the misalignment of the seats of the planetary gears, which can be found in the background art.

A second object of the present invention is to realize a device for converting a rectilinear reciprocating motion into a rotational motion, and vice versa, in which problems of anomalous loads on the bearings or bushings, or in general on the rolling (sliding) surfaces (interfaces) between the rotor and the planetary gear (s), are not encountered.

A third object of the present invention is to provide a device which can be easily balanced with the use of known techniques.

A fourth object of the present invention is to greatly simplify the structure of the device for converting a rectilinear reciprocating motion into a rotational motion and vice versa, with respect to the background art.

A further object of the present invention is to provide a device of a universal kind, accomplishing the function of transforming a rectilinear reciprocating motion into a rotational motion and vice versa, which may be employed as a replaceable module, in any kind of machine or equipment, according to the required dimensions and configurations suited to a specific application.

In particular, the present invention shall be applicable to the construction of compressors and of volumetric reciprocating internal combustion engines.

Said objects are attained by means of a device for converting a rectilinear reciprocating motion into a rotational motion and vice versa, which has the features contained in the independent claims 1,6, and 12.

The dependent claims 2 to 5,7 to 11, and 13 to 19, are particular embodiments or variants of the device.

The single inventive concept which characterizes all embodiments of the invention, so as to give a unique contribution with respect to the background art, consists in the fact that only one rotor is provided, and at least one planetary gear which is mounted in a cantilever fashion inside said rotor, in a way that the supports of the planetary gear are located all on the same side of the crank of that planetary gear.

Since the rotor is monolithic, or alternatively comprises a rigid group of integral parts, a misalignment of the seat (s) of the planetary gear (s) can never occur.

If more than one planetary gear is present, they are mounted in a cantilever fashion, while the power take-off is provided laterally, using a shaft carrying a gearwheel engaging another gearwheel which is integrally formed on the rotor. It should be noted that power is not necessarily drawn from the rotor by means of gearwheels; on the contrary, power may be drawn from the mechanism by any other means which is suited to transmit a rotational motion from one shaft to another shaft, wherein one of these shafts is located on the external part of the mechanism (for instance it is possible to use a transmission with chains or belts, etc.). Due to the fact that there is only one rotor, no misalignment of the seats of the planetary gears with respect to each other will occur, and no transfer of a couple from one rotor to the other is possible.

Obviously, it will be possible to provide several crank pins on the same crank, which are phase-shifted with respect to each other, so as to ensure optimum operation of the device ; in fact, the time distribution of the thrust of the pistons is more uniform

during a single 360° rotation of the output shaft.

Brief Description of Drawings The present invention and its advantages with respect to the background art will be illustrated in more detail only for illustrative and non-binding purposes, with reference to the annexed drawings, showing particular and preferred embodiments, wherein: FIG. 1 is a schematic representation of the classical crank mechanism; FIG. 2 is a schematic representation of the operation principle of the present invention and also of the other already known devices based on the principle of Cardano; FIG. 3 is a view of an assembly formed by a gearwheel with internal toothing, a planetary gear integral with a crank, and the crank itself, in the position corresponding to the TDC (top dead center) of the movable member or reciprocating piston; FIG. 4 is a view showing the assembly of Fig. 3 in a position different from the TDC; FIG. 5 is a view of an assembly comprising a gearwheel with external toothing, an intermediate gearwheel, a planetary gear integral with the crank, and a crank, in the position corresponding to the TDC of the piston; FIG. 6 is a view of the assembly of Fig. 5, in a position different from the TDC; FIG. 7 shows the principle of operation of a first device of the background art, in the

embodiment including two cylinders ; FIG. 8 shows the principle of operation of the device of Fig. 7, in the 4-cylinder version, which is also included in the background art; FIG. 9 shows the operation principle of a second device of the known art ; FIG. 10 schematically shows the operation of a third device of the background art; FIG. 11 is a side view and front view respectively, of the first embodiment of the present invention, which is based on the principle of Fig. 3, and which will be called "cantilever device with a single planetary gear" ; FIG. 12 is a longitudinal sectional view along the plane A-A of Fig. 11; FIG. 13 is an exploded partially sectioned view of the device shown in Fig. 12; FIG. 14 is a longitudinal sectional view of a variant of the first embodiment shown in Figs. 11-13; FIG. 15 is a longitudinal sectional view of a second variant of the first embodiment; FIG. 16 is a front and side view respectively of a second embodiment of the device of the present invention, which is also based on the operation principle of Fig. 3, and which will be called in the following"cantilever device with two planetary gears" ; FIG. 17 is a longitudinal sectional view along the plane B-B in Fig. 16 ;

FIG. 18 is a cross-sectional view on the plane A-A of Fig. 16 ; FIG. 19 is an exploded and longitudinal partially sectional view of the device shown in Figs. 16 to 18 ; FIG. 20 is a group of three views, including two front views on opposite ends, and one view in cross section, of one of two lateral and identical components of the rotor which makes part of the device shown in Figs. 16 to 19; FIG. 21 is a variant, shown in longitudinal section, of the device of the second embodiment of the present invention (Fig. 16) ; FIG. 22 is a longitudinal sectional view of the third embodiment, including only one planetary gear mounted in a cantilever fashion, with two crank pins arranged on opposite sides of the device ; FIG. 23 is a side view of a generic planetary gear, comprising two phase-shifted crank pins, each being connected to respective pistons ; FIG. 24 is a front and side view respectively, of the fourth embodiment of the present invention, which is based on the principle of Fig. 5, and which again forms a "cantilever device with a single planetary gear" ; FIG. 25 is a cross-sectional view on the plane A-A of Fig. 24 ; FIG. 26 is a cross-sectional view along the plane B-B of Fig. 24 ; FIG. 27 is a longitudinal sectional view taken along the plane C-C of Fig. 24.

Best modes of carrying out the invention After having described, in the critical review of the background art, all particular disadvantages of the conventional devices which make use of the principles of Figs.

3,4 on the one hand, and of Fig. 5,6 on the other, in the following a description will be given of several preferred solutions of the device of the present invention, all of them being based on said known principles (known in the literature under the name of"Cardano principle", although the latter is a pure geometrical theorem), but not including the aforementioned drawbacks.

In the description of the embodiments, the numerals are the same, with the exception of multiples of 100. For instance, 117 indicates the planetary gear of the first embodiment, 317 indicates the planetary gear of the third embodiment, a. s. o.

Moreover, the axes 01, 02,03 always have the same significance, in all figures.

The present invention solves the aforementioned problems, by proposing a device which is easy to realize, and which is suited to convert a rectilinear reciprocating motion into a rotational motion, and vice versa; this device will be called in the following discussion a"cantilever device", and the significance of this term will clearly result from the detailed description given below.

The device, which is based on the principles of Figs. 3 and 5, includes, in all its embodiments: 1) one or more planetary gears; 2) one rotor ; 3) means suited to impart rotational motions to the rotor and to the planetary gear (s), complying with the principles of Figs. 3 and 5.

Each planetary gear (117; 217a, 217b; 317, 417) may be realized monolithically or as a rigid group of several integral parts, and includes one or more crank pins (101 ; 201 ; 301a, 301b; 401), each of them being always arranged on only one side of the planetary gear supports (e. g. 108a and 108b in the first embodiment): this is the

meaning of the term"cantilever", that in the following discussion plays a fundamental role.

Moreover, the device includes one or more planetary gear supports (for instance 108a and 108b in Fig. 13) of axis 02 (see also Figs. 3 and 5). In case only one support is present, it should extend along a considerable distance along the planetary gear, thereby ensuring the proper operation of the device.

Said supports ensure the support, and allow the rotation, of the planetary gear.

The planetary gear further includes at least a gearwheel (116; 216 ; 316a, 316b ; 416) which is coaxial to said supports. Each crank pin (101 etc.) must have its axis 03 arranged parallel to the axis 02, and spaced apart from the latter by an amount D, equal to one fourth of the complete stroke (4D) of the axis 03. The axes of the crank pins are not necessarily coincident (see 03a and 03b in Fig. 23).

The rotor (109 ; 209 ; 309; 409), which in some embodiments is monolithically formed, and in other embodiments comprises a rigid group of integral parts, will include, as shown in more detail below: one or two seats for the planetary gear (s) (see e. g. 219a, b in Figs. 18, 19 and 20), each of them having the axis (02) parallel to the rotation axis 01 of the rotor, and shifted relative to the latter (01) by an amount D equal to one fourth of the piston stroke ; one or more supports for supporting the rotor with respect to the device base ; and a member used to draw or transmit power, denoted by 3 or 7.

In the device of the invention, the means used to impart to the planetary gear and to the rotor, rotational motions around the respective axes. such that when the planetary gear performs a rotation in any direction, the rotor performs a rotation equal to half that amount, and in the opposite direction, include stationary (that is non-movable) gearwheels with internal (6; Fig. 3) or external toothing (6 ; Fig. 5), which are implemented in the various embodiments by the gearwheels 106, 206,306a, 306b, 406 ; the latter engage the (fellow) gearwheels of the planetary gear (s), which are also comprised in said means.

Describing now the embodiments one by one, the first embodiment-shown in Figs.

11,12,13-includes a rotor 109 receiving a planetary gear 117. This embodiment is an implementation of the principle of Fig. 3. From the cross-sectional view A-A of Fig. 12 it can be observed that this rotor 109 forms a rigid group consisting of two parts, and therefore is not monolithic. One of said parts is integrally formed with an outwardly projecting portion, that is with the shaft 3. The rotor 109 is in turn contained inside a base or frame body 112, which is monolithically realized, while the power shaft 3 projects outwardly therefrom (in the following two different reference numbers-3 or 7-will be used for the power shaft, depending on whether it is connected or not connected to the rotor).

The power shaft allows to transmit or draw the power, to or from the device 100 of the first embodiment.

The rotor, as in the background art, obviously has the function to support the planetary gear, that is to"drag"the planetary gear 117 during its rotation according to the principle of Fig. 3 ; therefore, as known, the rotor has an aperture or slot, allowing mutual engagement between the gearwheel 116 of the planetary gear 117, and the stationary gearwheel 106 (integral with the frame body 112). The numbers 102a and 102b denote the sliding or rolling surfaces in two different regions of the planetary gear. Bushings (not indicated by reference numbers in Fig. 12) are interposed between the sliding (rolling) surfaces 102a and 102b of planetary gear, and the rotor 109, on the one hand, and between the rotor and the frame body 112, on the other hand. Obviously, if that part of the rotor 109 completely contained inside the device 100, is made of bronze, and the planetary gear 117 is made of steel, the bushings can be omitted altogether. Analogously, if the frame body is made of a material compatible with the material forming the rotor, it is not necessary to insert bushings between the rotor 109 and the frame body 112. This idea will be illustrated in more detail with reference to the following figure (Fig. 13).

Fig. 13 (exploded view) further illustrates the composition of the various elements

which form the device 100.

The planetary gear 117 is formed according to this figure (from left to right), by the following parts: - a crank pin 101 with axis 03; - a support surface 102a for bearings (or bushings), a gearwheel 116, and a second support surface 102b for bearings (or bushings), wherein the elements 102a, 102b, 116 are all coaxial to each other and have the same axis 02.

- The rotor, which is formed by assembling together the two elements 109a, 109b, has a seat along the axis 02, in which two bearings or bushings 108a, 108b provide adequate support for the planetary gear.

- An aperture or slot 121 is realized between these bushings, which allows the gearwheel 116 of the planetary gear 117 to emerge to the outside of the rotor 109, as has been already noted.

- The frame body 112 is a monolithic block, including the bushings 108c and 108d for the support and the rotation of the rotor 109, and the integrally formed stationary gearwheel with internal toothing 106.

From Fig. 12 we can see that the axis 03 of the crank pin 101 is parallel to, and arranged at a distance D from the axis 02 of the planetary gear 117, which in turn is spaced a distance D from the rotor axis 01, and further, it can be noted that D corresponds to the radius of the gearwheel 116 of the planetary gear 117, whereas D+D is the radius of the gearwheel with internal toothing 106, so that all conditions are satisfied in order that when the rotor rotates around its own axis 01 by a certain angle, the planetary gear rotates by twice that angle and in the opposite sense around its own axis 02, and, finally, the center 03 of the crank pin 101 will move along a rectilinear trajectory.

Obviously, the above described cantilever device corresponds to an illustrative and non-binding embodiment, since it may assume infinite architectures and sizes, according to specific design requirements, provided the condition is satisfied that the

planetary gear 117 is supported inside the rotor on only one side with respect to the crank pin 101.

For instance, in Fig. 14 the gearwheels 106 and 116 have been arranged"outside"the supports 108a and 108b, realized on the rotor 109, and to the left of the crank pin 101, whereas in Fig 15 the same gearwheels are located on the right of the crank pin 101, although, even in this case, these gearwheels are located"outside"of the supports obtained in the rotor 109.

It is important to note that since the rotor 109 of Figs. 12,13 and 14 is realized in the form of a rigid group of several integral parts, in this case it will be possible to further simplify the construction of the mechanism, thereby meeting one of the most important objects of the invention, that is, to simplify the application of the mechanism as an alternative to the ordinary crank mechanism. Actually, as has been said above, if in the embodiment of Fig. 12 the element 109a of the rotor is made of bronze or any other suitable anti-friction material, the bushings 108a, 108b, 108c, could be eliminated, by directly inserting the planetary gear 117 in the rotor 109, and the latter in the monolithic frame body 112.

The second embodiment of the device of the present invention is shown in the Figs 16 to 20. It forms a device 200 in which a single rotor 209 receives two planetary gears 217a, 217b, each having a respective crank pin 201a, 201b, phase-shifted to each other by 180°, and located on opposite sides of the rotor. In order to better explain the mechanism, also in this case reference is made to an exploded assembly (Fig. 19), which constitutes a further example of a cantilever mechanism based on the principle of Fig. 3, and which better shows the components. The planetary gears 217a, 217b are substantially identical to the planetary gear 117. The rotor 209, as shown in Fig. 19 (see also Fig. 17) is made of three rigidly assembled parts, 209a, 209b, 209c. The external parts 209a, 209c are identical, and they include, as may be seen from Fig. 20: - a zone 218, by which the rotor is supported during its rotation; a seat 219a, on

which the planetary gear 217a (217b) is supported during its rotation, in its front side; and a seat 219b in which the planetary gear 217b (217a) rotates, in its rear side; - a slot or aperture 221, from which emerges the gearwheel 216 of the planetary gear.

The numeral 212 (Fig. 19) indicates the frame body, on which the gearwheel with internal toothing 206 has been integrally-that is directly-formed, in addition to the two zones 220 inside which the rotor 209 rotates. At the center of this piece 212, where the gearwheel 206 is formed, there is obtained a slot 221b through which a gearwheel 214 (see Fig. 16) keyed on the driving shaft 7, may engage with the gearwheel 209b, which is integrally formed on the rotor 209. Obviously, the distances between the axes 03a-02a, 03b-02b, 02a-01, 02b-O1, must all be equal to D. The radius of each gearwheel 216 must be equal to D, and the radius of the gearwheel 206 must be equal to 2D.

It should be noted that the gearwheel 209b, integral with the rotor 209, may be replaced by any other member (a sprocket-wheel for chains, a pulley, etc.) suited to transmit (through chains, belts, a. s. o.) a rotational motion between to shafts, that is, in the present case, from the rotor 209 to the external shaft of the device. Therefore, the latter shaft does not necessarily have a gearwheel 214, but it may be provided with any kind of member which is compatible with a particular application and with the particular way of transmitting a motion thereto.

In addition, the external shaft of the device could also be not parallel to the rotor 209. All this depends on the particular motion transfer mechanisms employed.

The device of Figs. 16 to 20 is a cantilever mechanism with two opposite crank pins, each associated to a respective planetary gear, for the conversion of the rotational motion into a rectilinear reciprocating motion on two pins, and vice versa. Naturally, also in this situation, the arrangement shown in Figs. 16 to 20 is not binding (limitative) for what concerns the architecture of the system and especially for its dimensions, which may be adapted to a particular application, the only matter of relevance being that each crank pin 201a, 201b of the respective planetary gear, must

be located"outside"of the supports 202 of this planetary gear.

It should be noted that in the figures which have been just described, there are no bushings or bearings between the rotating and mutually coupled elements. This is due to the fact that an anti-friction material (e. g. bronze) is supposed to be used for the parts 209a and 209c of Fig. 19. Therefore, also in the application involving cantilever mechanisms with two planetary gears, the solution with a rotor formed by a rigid group of integral parts allows a simplification in the device structure.

In Figs. 16 to 20 it may be noted that the seats of the planetary gears 217a, 217b have been obtained in the rotor on opposite sides thereof, and are phase-shifted by 180° to each other ; however, this arrangement is not binding, even if it is the preferred one with regard to device balancing. The seats 219a, 219b could also be obtained on the rotor opposite sides and be phase-shifted with respect to each other by an angle different from 180°. It should be observed, however, that in the device shown in Figs. 16 to 20, and in all other devices falling inside the scope of the present invention, if a planetary gear is simply mounted inside its seat with its crank pin rotated by an angle"2a"with respect to its position shown in any figure, a trajectory is obtained for that crank pin, which is phase-shifted (tilted) by an angle"a"with respect to the trajectory of said pin, when mounted in the represented position. In particular, when a planetary gear is mounted with its crank pin rotated by 180° around the axis of the planetary gear itself, a trajectory is obtained for this crank pin, corresponding to a trajectory of rectilinear reciprocating motion, phase-shifted (tilted) by 90°. This means, with particular reference to Fig. 17, that a device for a 4- cylinder motor would be obtained, whose piston trajectories are arranged at 90° with respect to each other.

The above actions may be combined ; that is, assuming that on one side of the device shown in Figs. 16 and 17, the seat of (for instance) the planetary gear 217a has been realized with an inclination a with respect to the position of this seat as shown in the drawing (relative to 01), and further assuming that this planetary gear 217a is first

taken out of its seat, and thereafter reintroduced inside it, but rotated by-2a around 02 (axis of the planetary gear seat), then (as may be easily deduced from Fig. 4), it will be possible to obtain a device 200 similar to that shown in Figs. 16 and 17, wherein the movement of the planetary gear 217a is temporally phase-shifted, although the trajectory of the crank pin 201a remains the same as before, that is, parallel to the trajectory of the crank pin 201b of the other planetary gear 217b.

Fig. 21 shows a further example of a cantilever device with two planetary gears, each having a single crank pin (note that the numbering of components is the same as in Figs. 16 to 20, since this is a variant of the same embodiment). In this figure the gearwheels 216 of the planetary gears have been"transferred outside"of the rotor, and each of these gearwheels engages a respective gearwheel 206 with internal toothing.

In Fig. 22, there is shown a further example of a cantilever device with a single planetary gear 317, according to the third embodiment of the present invention, wherein two crank pins 301a, 301b are provided, disposed on opposite sides of the rotor 309.

Fig. 23 shows a generic planetary gear 17, which according to its configuration, may also be employed in the devices of the present invention. This figure shows that even two crank pins la, lb, which are phase-shifted with respect to each other, may be arranged on the same side of a planetary gear.

Finally, in Figs. 24 to 27, there is shown, only for illustrative purposes, a cantilever device (fourth embodiment) used for converting a rotational motion into a rectilinear reciprocating motion, which is based on the utilization of gearwheels having all an external toothing. In this case too, the principle of the invention is complied with, according to which a single rotor is provided, and the supports of the planetary gear are all located on the same side of the crank (meaning of"cantilever device").

This device has a rotor 409 comprising two parts 409a and 409b.

It should be noted, that having a rotor formed by a group of parts, is not only

advantageous from the point of view that bushings can be omitted in some applications, but also-as in the specific case of Fig 27-, it may be necessary for allowing the assembling of the parts which make up the device.

In the cross-section C-C of Fig. 27, the planetary gear 417 which is contained inside the rotor 409, is formed by the following principal parts: - a crank pin 401 ; - a first support surface 402a for the planetary gear ; - a gearwheel 416 ; - a second support surface 402b.

The axis 03 of the crank pin 401 is parallel to, and spaced apart a distance D from, the axis 02 of the planetary gear. The planetary gear 417, contained inside the rotor 409, is in engagement with (Fig. 25, cross-section A-A) the gearwheels 422a and 422b of shafts 413a and 413b; the latter project out of the rear side of the rotor 409, and mesh with (cross-section B-B, Fig. 26) the stationary gearwheel 406 (with external toothing), by means of the gearwheels 422c and 422d.

It should be noted that the shafts 413a, b and their gearwheels 422a to 422b, accomplish the function of the intermediate gearwheel 13 shown in Fig. 5, which only illustrates the principle of operation in case of gearwheels having all an external toothing.

Although this principle was known per se, a"cantilever device"of the kind shown- for instance-in Fig. 27, has not been realized yet.

The rotor 409 is formed by the elements 409a and 409b, which are rigidly connected together. In this rotor, as has been said above, there are obtained the seats of the bushings for the planetary gear 417 and for the shafts 413a, b. The portion 3 of the rotor 409 (integrally formed with the part 409a), corresponds to the power shaft (see longitudinal section C-C, Fig. 27). The latter extends through the fixed gearwheel 406 and the related stationary support 423 (which is rigidly connected to the device base), and constitutes a first support for the rotor 409, whereas the second support

and rotation surface of the rotor, is formed by the external surface of the part 409b (which rotates with respect to the device base 424). It is important to observe that a necessary requirement for device operation is that D be the distance between the mutually parallel axes of the rotor 409 and the planetary gear 417, and that the teeth of the gearwheels 416,422a/422b, 422c/422d and 406, fulfil the following equation: (Z406/Z422oX422d) * (Z422a/422b/Z416) = 2 where Z is the number of teeth, and the"/"in the symbols 422a/422b, 422c/422d indicates the alternative"or".

In this case too, it is important to note that particular configurations and sizes of the various elements are not binding for the construction of the device and may be adapted to a particular application.

The only conditions to be fulfilled are: - the device must satisfy the principle of Fig. 5; - the device includes only one rotor; - the planetary gear has its supports located only on one side of the crank pin (s).

In Figs. 24 to 27 the mechanism includes, for balancing reasons, two shafts, 413 a and 413b, as shown in the cross-sections A-A and B-B; however, this solution is not binding, so that it will be possible to realize devices with only one intermediate shaft, or devices with more than two intermediate shafts.

It is necessary, however, that the gear train which starts with the stationary gearwheel 406 and ends with the gearwheel 416 of the planetary gear 417, ensures oppositely directed rotations-one rotation being twice the other rotation-of the planetary gear 417 and of the rotor 409 respectively.

All cantilever devices described till now can be perfectly balanced by means of simple counterweighing operations, that can be performed on the rotor and on the planetary gear.

It is important to stress and repeat once more that in all devices based on the present invention, a characterizing feature consists in the use of a single rotor for each

device. Actually, the presence of only one rotor allows to solve the misalignment problems of the devices of the background art, since all planetary gear (s) supports are perfectly aligned and integral to each other, due to the fact that they have been realized on the same member, and the latter being monolithically realized in some embodiments, or being formed as a rigid group of several integral parts, in other embodiments.