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Title:
ROTATING VOLUMETRIC MACHINE WITH RADIAL PISTONS
Document Type and Number:
WIPO Patent Application WO/2013/160835
Kind Code:
A1
Abstract:
Rotating volumetric machine (1) with radial pistons wherein one between the inner ring (16) and the joint (25), that connects in rotation the inner ring (16) and the relative rotor element (7), comprises at least a first seat (26) and the other supports in rotation at least a first revolving element (27) around a relative axis (27a), the first revolving element (27) being fitted in said first seat (26) and cooperating with it to transmit a torque to the joint (25); wherein at least one between the rotor element (7) and the joint (25) comprises at least a second seat (28) and the other supports in rotation at least a second revolving element (29) around a relative axis (29a), the second revolving element (29) being fitted in the second seat (28) and cooperating with it to transmit a torque to the rotor element (7); the first and the second revolving element (27, 29) rolling around the respective axes (27a, 29a) along at least a containment wall (26a, 28a) delimiting the respective seats (26, 28) during the rotation of the inner ring (16) and of the rotor element (7).

Inventors:
PECORARI DAVIDE (IT)
Application Number:
PCT/IB2013/053212
Publication Date:
October 31, 2013
Filing Date:
April 23, 2013
Export Citation:
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Assignee:
ECOTECH IND S R L (IT)
International Classes:
F03C1/04; F01B1/06; F04B1/04
Domestic Patent References:
WO2003060321A12003-07-24
WO2003060321A12003-07-24
Foreign References:
US4131056A1978-12-26
US2556717A1951-06-12
Attorney, Agent or Firm:
BRUNACCI, Marco (Via Scaglia Est 19-31, Modena, IT)
Download PDF:
Claims:
CLAIMS

1) Rotating volumetric machine (1) with radial pistons comprising:

- at least a distributor (4) of a working fluid having at least a supplying channel (5) and at least a discharge channel (6);

- at least a rotor element (7) mobile in rotation around a first axis (8) and having a plurality of radial chambers (11) communicating with at least one between said supplying channel (5) and said discharge channel (6), inside each of said radial chambers (11) being housed a relative piston (12) mobile along at least a sliding direction (13);

- at least a contrast device (14) of the radial thrusts of said pistons (12) comprising at least an outer ring (15) and an inner ring (16) arranged around said rotor element (7), wherein said inner ring (16) is associated mobile in rotation with said outer ring (15) around a second rotation axis (17) eccentric with respect to said first axis (8); said contrast device (14) comprising fastening means (21) suitable for fastening each of said pistons

(12) to said inner ring (16) along the relative sliding direction (13) and to allow their shift along a further direction transversal to said sliding direction

(13) , the shift of said pistons (12) bringing in rotation said inner ring (16) around said second axis (17);

at least a connection joint (25) placed between said inner ring (16) and said rotor element (7) and suitable for connecting them in rotation to each other; characterized by the fact that one between said inner ring (16) and said joint (25) comprises at least a first seat (26) and the other supports in rotation at least a first revolving element (27) around a relative axis (27a), said first revolving element (27) being fitted in said first seat (26) and cooperating with it to transmit a torque to said joint (25)

and characterized by the fact that at least one between said rotor element (7) and said joint (25) comprises at least a second seat (28) and the other supports in rotation at least a second revolving element (29) around a relative axis (29a), said second revolving element (29) being fitted in said second seat (28) and cooperating with it to transmit a torque to said rotor element (7);

said first and second revolving element (27, 29) rolling around the respective axes (27a, 29a) along at least a containment wall (26a, 28a) delimiting the respective seats (26, 28) during the rotation of said inner ring (16) and of said rotor element (7).

2) Machine (1) according to claim 1, characterized by the fact that said first and second seat (26, 28) are arranged transversally to each other.

3) Machine (1) according to claim 1 or 2, characterized by the fact that one between said inner ring (16) and said joint (25) comprises at least two of said first revolving elements (27) having the respective rotation axes (27a) parallel and spaced apart from each other.

4) Machine (1) according to claim 3, characterized by the fact that the other between said inner ring (16) and said joint (25) comprises at least two of said first seats (26) inside each of which is housed a relative first revolving element (27).

5) Machine (1) according to one or more of the preceding claims, characterized by the fact that one between said rotor element (7) and said joint (25) comprises at least two of said second revolving elements (29) having the respective rotation axes (29a) parallel and spaced apart from each other.

6) Machine (1) according to claim 5, characterized by the fact that the other between said rotor element (7) and said joint (25) comprises at least two of said second seats (28) inside each of which is housed a relative second revolving element (29).

7) Machine (1) according to one or more of the preceding claims, characterized by the fact that said joint (25) comprises said first and second seats (26, 28), said inner ring (16) and said rotor element (7) supporting, respectively, said first and said second revolving elements (27, 29).

8) Machine (1) according to one or more of the preceding claims, characterized by the fact that said joint (25) has a through hole (30) defining an internal profile (25b) and by the fact that said second seats (28) are defined along said internal profile (25b) on opposite sides of said hole (30) and have at least an open end and which faces on the hole itself, said first seats (26) being defined externally to said internal profile (25b).

9) Machine (1) according to one or more of the preceding claims, characterized by the fact that said first seats (26) are defined along the external profile (25 a) of said joint (25) on opposite sides of said hole (30) and have at least a relative end which is open and facing to the outside.

10) Machine (1) according to one or more of the claims from 1 to 8, characterized by the fact that said seats (26) have both relative ends closed to define a closed slot with an elongated shape.

11) Machine (1) according to one or more of the preceding claims, characterized by the fact that each of said seats (26, 28) has two containment walls (26a, 28a) facing each other and between which the relative revolving elements (27, 29) are fitted and by the fact that the distance between said containment walls (26a, 28a) is greater than the diameter of the relative revolving elements (27, 29), the latter coming in contact with only one containment wall (26a, 28a) of the relative seat (26, 28) during the rotation of said inner ring (16) and of said rotor element (7).

12) Machine (1) according to one or more of the preceding claims, characterized by the fact that said revolving elements (27, 29) are of the type of a sliding bearing or of the type of a rolling bearing.

13) Machine (1) according to one or more of the preceding claims, characterized by the fact that at least one of said revolving elements (27, 29) comprises at least a layer of an elastically yielding material.

14) Machine (1) according to one or more of the preceding claims, characterized by the fact that the axial thickness of said revolving elements (27, 29) is greater than the thickness of the containment walls (26a, 28a) of the relative seats (26, 28), each of said revolving elements (27, 29) coming into contact with the relative containment wall (26a, 28a) along the whole extension of the same.

15) Machine (1) according to one or more of the preceding claims, characterized by the fact that said fastening means (21) comprise, for each of said pistons (12), a first and a second locator element (22, 24) integrally associated with said inner ring (16) and defining, respectively, a first and a second locator surface (22a, 24a) arranged facing each other and transversal to the relative sliding direction (13) and with which the corresponding piston (12) cooperates, said second locator element (24) being fitted inside the relative piston (12) through an opening defined on the piston itself, the head (12a) of the latter cooperating with said first locator surface (22a).

16) Machine (1) according to one or more of the preceding claims, characterized by the fact that said fastening means (21) comprise at least a slot extending along said further direction and defined in each of said pistons (12), the latter moving with respect to said second locator element (24) along said slot.

17) Machine (1) according to one or more of the claims from 1 to 15, characterized by the fact that said fastening means (21) are suitable for allowing the shift of each of said pistons (12) with respect to said inner ring (16) along at least a guide plane transversal to the corresponding sliding direction (13), at least one of said locator surfaces (22a, 24a) defining said guide plane.

18) Machine (1) according to claim 17, characterized by the fact that said fastening means (21) comprise at least an intermediate element placed between each of said pistons (12) and the relative second locator surface (24a), on said intermediate element being defined at least an elongated slot inside which is fitted said second locator element (24), said intermediate element being mobile in translation and in rotation with respect to the second locator element itself and being released from the relative piston (12).

19) Machine (1) according to claim 17, characterized by the fact that the inner walls (12c) of said pistons (12) are spaced apart from the lateral surface (24b) of the relative second locator elements (24) and by the fact that said fastening means (21) comprise, for each of said pistons (12), at least an intermediate element (32, 33) fitted on the relative second locator element (24) and placed between the second locator surface (24a) and a contact surface (12b) defined in correspondence to the inner wall (12c) of the corresponding piston, said intermediate element (32, 33) being mobile with respect to said second locator element (24) and with respect to said piston (12) and supporting the latter in its shift along the relative guide plane.

20) Machine (1) according to claim 19, characterized by the fact that said fastening means (21) comprise, for each of said pistons (12), two of said intermediate elements (32, 33), of which a first intermediate element (32) resting on said second locator surface (24a) and a second intermediate element (33) resting on said first intermediate element (32) and released with respect to it, said intermediate elements (32, 33) having a substantially circular section, wherein the internal and external diameters of the second intermediate element (33) are greater, respectively, than the internal and external diameters of the first intermediate element (32), and the inner walls (12c) of said pistons (12) coming in contact in succession with the external profile of the relative second and of the relative first intermediate element (33, 32) during their shift along said guide plane.

Description:
ROTATING VOLUMETRIC MACHINE WITH RADIAL PISTONS

Technical Field

The present invention relates to a rotating volumetric machine with radial pistons.

Background Art

The rotating volumetric machine with radial pistons to which this invention relates can work both as a pump and an engine, such as an internal combustion engine.

Known rotating volumetric machines generally comprise:

- a central distributor that defines at least one supplying channel and a discharge channel for the working fluid;

- a rotor element mobile in rotation around a first axis and with a plurality of radial chambers communicating with at least one between the supplying channel and discharge channel and in which the relative pistons are housed mobile along a sliding direction;

- a contrast device against the radial thrust of the pistons, which comprise at least one fixed outer ring and one inner ring mobile in rotation with respect to the external ring around a second rotational axis eccentric to the first axis, the inner ring being fixed to the pistons along their sliding direction;

- a joint placed between the inner ring and the rotor and suitable for connecting them in rotation.

WO 03060321 describes a rotating volumetric machine in which the pistons are associated to the inner ring by means of a dovetail type connection that allows the shift of the pistons themselves along a direction that is perpendicular to the sliding direction. The movement of the pistons along the relative sliding directions causes the rotation of the inner ring around the second axis.

According to WO 03060321, the joint connecting in rotation the inner ring to the rotor element is fitted with four seats staggered by 90° from each other, in which the respective protrusions are fitted sliding.

More specifically, inside each pair of seats aligned to each other, a pair of protrusions is arranged, of which a first pair of protrusions integral to the inner ring and a second pair of protrusions integral to the rotor element. As the inner ring and the rotor element rotate, the protrusions slide inside the relative seats defined on the joint, which therefore moves in an alternate rotary- translational motion.

These volumetric machines however have some drawbacks.

They in fact lose large amounts of energy due to the sliding friction generated, in use, between the protrusions on the inner ring and on the rotor element and the relative seats defined on the joint.

Another drawback consists in the fact that, during the transmission of the rotational motion, high intensity pulsating radial forces are generated on the joint, due in particular to the variation of position, in use, of the rotational axis of the joint itself. As is known, as mechanical transmission organs are generally in an oil bath, the drawback stated above also means that the meatus of oil between the protrusions and the relative seats is not constant, thus causing uneven wear on the parts in contact.

Again, in the machines of known type, the working tolerances play a fundamentally important role in order to ensure their correct operation. More specifically, the clearance between the protrusions and the relative seats must be sufficiently small to avoid, during motion transmission, mutual misalignment and consequently high peak pressures between the parts in contact, which in some cases may even lead to breakage. Moreover, the greater the clearance between the protrusions and relative seats, the greater the noise of the volumetric machine. At the same time there must be sufficient clearance to allow the correct movement of the mutually moving parts. It thus follows that the working tolerances must be very close and carefully assessed to allow on one hand the correct operation of the volumetric machine and on the other hand avoid unwanted breakages and vibrations. This requires special attention during the design and production phases, which translates into long production times and higher costs.

We also need to consider that the surfaces subject to mutual friction must undergo different surface treatments to make them harder and offer greater mechanical strength, to prevent the parts in contact during use from deforming, leading to abnormal stresses and significantly reducing the machine performance.

Another drawback lies in the fact that the surfaces of mutually moving parts may weld, particularly in the case of micro-shifts of the protrusions inside the relative seats due to minor axial misalignments.

Yet another drawback in the known machines lies in the fact that the presence of the dovetail connection between the pistons and the inner ring do not correctly balance the forces that act on the pistons themselves as the balancing area, i.e. the area of the piston which acts on the inner ring, is lower than the thrust surface of the piston itself.

Moreover, the forced direction of movement of the piston with respect to the inner ring defined by the dovetail connection may lead to the formation of "hot" areas in which the lubricant film between the mutually moving parts disappears, with the consequent risk of seizure.

Description of the Invention

The main aim of the present invention is to provide a rotating volumetric machine with radial pistons which, compared to known rotating volumetric machines, drastically reduces the loss of energy due to the friction that occurs during the motion transmission from the inner ring to the rotor element.

Within this aim, one object of this invention is to provide a rotating volumetric machine with radial pistons which during use maintains a practically constant oil film between the mutually moving parts which transfer the motion from the inner ring to the rotor element.

One object of this invention is, compared to the known machines, to drastically reduce the influence of the working tolerances on the correct operation of the machine itself. More specifically, one object of this invention is to provide a rotating volumetric machine with radial pistons which can be designed and manufactured with less strict working tolerances than those of known machines, without negatively affecting performance, at the same time reducing production times and costs.

Another object of this invention is to provide a machine that is drastically less noisy than those of known type.

Another object of this invention is to provide a rotating machine with radial pistons which can be designed for breakage rather than for deformation, i.e. that is able to operate correctly even in the presence of slight deformations of the mutually moving parts.

Yet another object of this invention is to avoid unwanted welds between the mutually moving parts.

This invention also aims to improve the hydraulic balancing of the piston and maintain correct lubrication between the pistons and the inner ring, in order to reduce as far as possible the risk of seizure.

Another object of the present invention is to provide a rotating volumetric machine with radial pistons which allows to overcome the mentioned drawbacks of the state of the art in the ambit of a simple, rational, easy and effective to use as well as low cost solution.

The above objects are achieved by the rotating volumetric machine with radial pistons according to claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become more evident from the description of a preferred, but not sole, embodiment of a rotating volumetric machine with radial pistons, illustrated purely as an example but not limited to the annexed drawings in which:

Figure 1 is a longimdinal section view of a volumetric machine according to the invention;

Figure 2 is a section view along the track plane II-II in figure 1 ;

Figure 3 is a section view of the fastening means of the machine in figure 1; Figure 4 is an axonometric yiew of the machine in figure 1;

Figure 5 is a plan view of the correcting joint of the machine in figure 4;

Figure 6 is a plan view of a connecting joint in an embodiment alternative to that in figure 5;

Figure 7 is a section view of the coupling between a rotating element and the relative seat.

Embodiments of the Invention

With particular reference to such figures, globally indicated by 1 is a rotating volumetric machine with radial pistons. As stated above, the machine 1 can work both as a pump and an engine.

The machine 1 comprises a bearing structure 2, 3 comprising a first and second element 2 and 3 hollow inside and mutually coupled using screwing means which are not represented in the figures.

The bearing structure 2, 3 defines a chamber in which a distributor 4 of a working fluid is housed, such as gas, air, water, oil, etc...

The distributor 4 comprises at least a supplying channel 5 and at least a discharge channel 6 of the working fluid.

More specifically, the supplying channel 5 comprises a cut 5a connected to a supplying device of the working fluid (not visible in detail in the figures) and two breakings 5b, 5c communicating with the cut 5a by means of two pipes 5d, 5e through which the working fluid flows. The breakings 5b, 5c are communicating with each other and between them is a relative strengthening ribbing.

Similarly, the discharge channel 6 comprises a cut 6a connected to a discharge device of the working fluid (not visible in detail in the figures), and two breakings 6b, 6c communicating with the cut 6a by means of two pipes 6d, 6e through which the working fluid flows. The breakings 6b, 6c are communicating with each other and between them is a relative strengthening ribbing.

The distributor 4 has a longitudinal symmetry axis and is floating inside the chamber defined by the elements 2 and 3. More specifically, the distributor 4 is angularly mobile to vary the timing of the machine 1 , as will be explained in more detail below. The angular rotation of the distributor 4 is done by means that are not shown in the figures. Moreover, given that, as said, the machine 1 can work both as a pump and as an engine, the distributor 4 is also axially mobile.

La machine 1 then comprises at least one rotor element 7 arranged around the distributor 4 and mobile in rotation around a first axis 8. The first axis 8 of rotation of the rotor element 7 coincides substantially with the longitudinal symmetry axis of the distributor 4 which, on the other hand, is locked in rotation. Between the distributor 4 and the rotor element 7 are placed first rolling means 9,10, composed, e.g., by a first and second bearing 9 and 10. The bearings 9 and 10 maintain the coaxial position between the distributor 4 and the rotor element 7.

Appropriately, between the rotor element 7 and the first element 2 are placed second rolling means 19,20 composed, e.g., by a tliird and fourth bearing 19 and 20.

The rotor element 7 comprises a plurality of radial chambers 11 , each of which is in coimnunication with at least one between the pipes 5 and 6 and more specifically with one of the breakings 5b, 5c, 6b, 6c. As the rotor element 7 rotates around the first axis 8, each chamber 11 is placed in hydraulic communication, in sequence, with each of the breakings 5b, 5c, 6b, 6c.

Inside the chambers 11 the respective pistons 12 are housed, which are mobile in translation along a respective sliding direction 13.

More specifically, the sliding direction 13 coincides substantially with the symmetry axis of the relative chamber 11.

The machine 1 comprises, then, at least one contrast device 14 against the radial thrust of the pistons 12.

The contrast device 14 comprises at least an outer ring 15 and at least an inner ring 16 arranged around the rotor element 7. The inner ring 16 is mobile in rotation with respect to the outer ring 15 around a second axis 17 of rotation substantially parallel and misaligned with respect to the first axis 8, as can be seen in figure 1.

More specifically, the outer ring 15 is fixed and integrally associated with the first element 2 and between the outer ring itself and the inner ring 16 are positioned rolling means 18 such as, e.g., one or more series of cylindrical rollers. The assembly made up of the outer ring 15, rolling means 18 and inner ring 16 thus defines an integrated bearing, on which rolling tracks are made in the elements of the machine 1 itself.

The second axis 17 of rotation of the inner ring 16 coincides substantially with the symmetry axis of the outer ring 15 which, as stated above, is offset with respect to the first axis 8 of rotation of the rotor element 7. The misalignment of the axes 8 and 17 defines the displacement of the machine 1.

Advantageously, the machine 1 comprises adjusting means of the position of the second axis 17, not shown in the figures, which therefore adjust also the eccentricity with respect to the first axis 8. By modifying the eccentricity between the two axes 8 and 17 the displacement of machine 1 is consequently modified which is therefore of variable displacement type.

The contrast device 14 comprises fastening means 21 which fix each piston to the inner ring 16 along the relative sliding direction 13 and allow the shift along at least a further transversal direction to the sliding direction itself.

The shift of the pistons 12 transversely to their sliding direction 13 is required to allow the pistons themselves to adapt to the geometrical conditions which change during the rotation of the rotor element 7 and the inner ring 16.

More specifically, due to this shift, the point in which the force exerted by the pistons 12 acts on the inner ring 16 is offset with respect to their sliding direction 13, from which it is seen that, considering the eccentricity of the axes 8 and 17, this force has a radial component and a tangential component on the inner ring itself and therefore causes its rotation around the second axis 17. It follows therefore that the shift of the pistons 12 inside the relative chambers

11 causes the rotation of the inner ring 16 around the second axis 17.

For more details on the rotational kinematics of the inner ring 16 refer to the contents of patent WO 03060321, here included for reference.

Advantageously, the fastening means 21 comprise, for each piston 12, at least a first locator element 22 and a second locator element 24 integrally associated with the inner ring 16. The first and second locator elements 22 and 24 define a first and a second locator surface 22 a and 24a respectively, facing one another and arranged transversally with respect to the sliding direction 13 of the piston

12 and between which the piston itself is positioned.

More specifically, each piston 12 is suitable for cooperating with the first locator surface 22a by means of its head 12a and with the second locator surface 24a by means of a contact surface 12b.

Preferably, the locator surfaces 22a and 24a are arranged perpendicularly to the sliding direction 13 of the relative piston 12. The second locator element 24 is fitted inside the relative piston 12 through a through opening defined in it.

Preferably, each second locator element 24 has a stem fitted through the relative piston 12 and associated integrally to the inner ring 16 at one end and has, on the opposite end of the stem with respect to the inner ring 16, a head which defines the second locator surface 24a. The stem defines a lateral surface 24b which extends substantially parallel to the sliding direction 13 of the relative piston 12. Appropriately, the stem of the second locator element 24 has a substantially circular section, which can be constant or variable along the longitudinal extension thereof.

The fastening means 21 can have various embodiments, the figures enclosed represent only one of these.

In a first embodiment, not shown in the figures, the fastening means 21 comprise at least one slot defined in each piston 12 and extending along the further shift direction of the pistons themselves. In this embodiment, the relative second locator element 24 is fitted inside a corresponding slot and each piston 12 is mobile with respect to the relative second locator element itself along the direction defined by the slot itself. During the shift along the further direction defined by the slot, each piston 12 rests with its head 12a against the first locator surface 22a.

Advantageously, the fastening means 21 are shaped in such a way as to allow the shift of each piston 12 along at least one guide plane transversal to the corresponding sliding direction 13. In this case, therefore, the fastening means 21 are shaped in such a way that the pistons 12 have two levels of freedom with respect to the inner ring 16.

Appropriately, the guide plane is defined by at least one of the locator surfaces 22a, 24a.

In a second embodiment, also not represented in the figures, the fastening means 21 comprise at least an intermediate element placed between each piston 12 and the relative second locator surface 24a and on which at least one elongated slot is defined. The relative second locator element 24 is fitted inside the slot and the intermediate element is mobile in rotation around the second locator element itself. More specifically, the intermediate element is placed between the inner walls 12c of the relative piston 12 and is released in rotation with respect to it; each piston 12 therefore moves with respect to the second locator element 24 along the direction defined each time by the orientation of the slot obtained on the intermediate element.

In a third embodiment, represented in the figures, the inner walls 12c of each piston 12 are spaced apart from the lateral surface 24b of the relative second locator element 24 and the fastening means 21 comprise at least one intermediate element 32,33 Fitted on the relative second locator element 24 and placed between the second locator surface 24a and a contact surface 12b defined in correspondence to the inner wall 12c of the corresponding piston 12. This intermediate element 32, 33 is mobile both with respect to the second locator element 24 and the piston 12, supporting the latter during its shift along the relative guide plane. In this third embodiment, the intermediate element 32,33 is therefore contained between the inner walls 12c of the relative piston, where the distance between two areas of the inner side walls 12c arranged on opposite sides of the relative second locator element 24 is greater than the diameter of the latter, obviously in the case in which it has a substantially circular section.

Preferably, the fastening means 21 comprise at least two intermediate elements 32, 33, of which a first intermediate element 32 and a second intermediate element 33 released to one another, placed between each piston 12 and the relative second locator element 24.

As can be seen in particular in figure 3, the first intermediate element 32 rests against the second locator surface 24a and the second intermediate element 33 rests on one side against the first intermediate element 32 and on the other against the contact surface 12b.

The intermediate elements 32, 33 are mobile with respect to the relative second locator element 24, their internal diameter being greater than the external diameter of the relative lateral surface 24b, and with respect to the relative piston 12. More specifically, the intermediate elements 32 and 33 have a substantially circular section and their external diameters are less than the internal diameter of the pistons 12 while their internal diameters are greater than the external diameter of the second locator elements 24.

Appropriately the internal and external diameters of the second intermediate element 33 are greater, respectively, than the internal and external diameters of the first intermediate element 32. During the shift of each piston 12 along the relative guide plane, the inner walls 12c thereof come into contact in sequence with the second and the first intermediate element 33, 32 moving them towards the second locator element 24. During the shift of each piston 12, the contact surface 12b remains resting on the second intermediate element 33 and the first intermediate element 32 remains resting on the second locator surface 24a.

The two intermediate elements 32 and 33 therefore allow the relative piston 12 to remain resting against the relative second locator surface 24a and their different diameters allow the piston itself to move along a wide travel with respect to the second locator element 24.

The head 12a of the pistons 12 is therefore not solid but has a through hole through which the relative locator element 24 is fitted.

This shape of the fastening means 21 allows the optimisation of the hydraulic balancing of the pistons 12 and allows them to shift with respect to the inner ring 16 even in the presence of warmer contact areas than others, e.g. due to the reduction in meatus of oil in these areas. In these conditions, in fact, the pistons 12 rotate around the hot areas, which therefore act as a hinge, positioning themselves autonomously in a different area and thus allowing them to cool. The machine 1 comprises, then, at least one connection joint 25, placed between the rotor element 7 and the inner ring 16 and suitable for connecting them in rotation around the respective axes 8 and 17.

The joint 25 is therefore suitable for transmitting the rotational motion from the inner ring 16, which, as we have seen, takes the motion from the shift of the pistons 12 along the relative sliding directions 13, to the rotor element 7.

According to the invention, one between the inner ring 16 and the joint 25 comprises at least a first seat 26 and the other supports in rotation at least a first revolving element 27 rotating around a relative axis 27 a, where the first revolving element 27 is fitted inside the first seat 26 and is suitable for cooperating with it to transmit a drive torque to the joint 25.

Similarly, one between the joint 25 and the rotor element 7 comprises at least a second seat 28 and the other supports in rotation at least a second revolving element 29 rotating around a relative axis 29a, where the second revolving element 29 is fitted inside the second seat 28 and is suitable for cooperating with it to transmit a drive torque to the rotor element 7.

According to the invention, the revolving elements 27 and 29 come into contact with at least a containment wall 26a, 28a which delimits the relative seat 26, 28 and roll along it around their respective axes 27a, 29a during the rotation of the inner ring 16 and the rotor element 7.

Each seat 26, 28 also has two containment walls 26a, 28a facing and spaced apart from each other, the revolving elements 27, 29 being positioned between the relative containment walls 26a, 28a. The containment walls 26a, 28a extend substantially parallel to the axes 27a, 29a of the revolving elements 27, 29. Advantageously, the distance between the containment walls 26a, 28a of a relative seat 26, 28 is bigger than the diameter of the revolving element 27, 29 fitted in the seat itself, in such a way that the revolving element itself comes into contact with only one containment wall 26a, 28a and is free to roll along it. This is particularly advantageous as it prevents the relative friction between the revolving element 27, 29 and the relative seat 26 ,28, consequently reducing the loss of energy due to friction.

The joint 25 therefore carries out a rotary-translational movement in the chamber defined by the bearing structure 2, 3 and the position of its axis of rotation varies substantially with continuity both with respect to the joint itself and to the axes 8, 17.

The revolving elements 27, 29 are therefore integral in rotation to the inner ring/ oint/rotor element which supports them and are released in rotation with respect to them around the relative axes 27a, 29a.

The revolving elements 27, 29 have a substantially circular section. Preferably, the revolving elements 27, 29 have a substantially cylindrical shape and their outer lateral surface comes into contact with the relative containment wall 26a, 28a. The outer lateral surface of the revolving elements 27, 29 defines at least a line of contact on the relative containment wall 26a, 28a. In other words, as can be seen in figure 7, by tracing a plane with a section substantially perpendicular to a containment wall 26a, 28a and passing through the axis of rotation of the relative revolving element 27, 29, we can see how the contact between them defines a continuous segment, identified by letter d in the figure.

Advantageously, the thickness of the revolving elements 27, 29, here with the term thickness meaning the dimension along the relative axis 27a, 29a, is greater than the thickness (measured along the same direction) of the corresponding wall 26a, 28a on which they rest, in order to come into contact with such wall 26a, 28a along its whole extension thus ensuring uniform distribution of the load on it. This ratio between the thickness of the revolving elements 27, 29 and that of the walls 26a, 28a allows the joint to support high loads and high rotational speeds.

The revolving elements 27, 29 are preferably made up of sliding or roller bearings and the relative containment walls 26a, 28a come into contact with their outer ring.

Appropriately, the axis 27a of the first revolving element 27 is substantially parallel to the axes 8, 17 and is offset at least with respect to the second axis 17; similarly, the axis 29a of the second revolving element 29 is substantially parallel to the axes 8, 17 and is offset at least with respect to the first axis 8. Advantageously, the seat 26 and 28 are arranged transversally to each other and, preferably, are arranged at right angles to each other.

In a preferred embodiment, one between the inner ring 16 and the joint 25 supports in rotation at least two first revolving elements 27 around the relative axes 27a, which are arranged parallel and spaced apart from each other. In this embodiment, at least one of the axes 27a, preferably both, is offset at least with respect to the second axis 17.

Appropriately, the other between the inner ring 16 and the joint 25 comprises at least two first seats 26, each of which is suitable for housing a relative first revolving element 27. More specifically, the two first seats 26 have an elongated shape and are substantially aligned together along the respective directions of longitudinal extension.

Other alternative embodiments cannot however be ruled out, in which the machine 1 comprises two first revolving elements 27 which are fitted in the same first seat 26 which is therefore unique.

Similarly, one between the rotor element 7 and the joint 25 supports in rotation at least two second revolving elements 29 around the relative axes 29a, which are arranged parallel and spaced apart from each other. In this embodiment, at least one of the axes 29a, preferably both, is offset at least with respect to the first axis 8.

Appropriately, the other between the rotor element 7 and the joint 25 comprises at least two second seats 28, each of which is suitable for housing a relative second revolving element 29. More specifically, the two second seats 28 have an elongated shape and are substantially aligned together along the respective directions of longitudinal extension. Other alternative embodiments cannot however be ruled out, in which the machine 1 comprises two second revolving elements 29 which are fitted in the same second seat 28 which is therefore unique.

In the preferred embodiment shown in the figures, the seats 26 and 28 are defined on the joint 25, while the inner ring 16 and the rotor element 7 support the first and the second revolving elements 27 and 29, respectively.

More specifically, the joint 25 comprises two first seats 26 and two second seats 28, where the first seats 26 are arranged in a substantially aligned way to each other and at right angles to the second seats 28, the latter being substantially aligned together. As can be seen in figures 4 and 5, each seat 26, 28 is defined by a relative through slot and having at least one blind end. The joint 25 therefore has four through slots, each with at least one blind end, where each of the said slots is arranged substantially at right angles to the adjacent slot. Each first seat 26 is therefore angularly followed and preceded by a relative second seat 28, where the first and second seats 26 and 28 are angularly staggered by 90° to each other.

Advantageously, the joint 25 has an external profile 25a and a through hole 30 defining an internal profile 2 b. Appropriately, the first and second seats 26 and 28 are arranged on opposite sides with respect to the hole 30.

More in particular, the second seats 28 are defined along the internal profile 25b and have at least an open end corruTiunicating with the hole 30 while the first seats 26 are external to the internal profile 25b, i.e. they do not face on the hole 30. This particular arrangement of the second seats 28 allows to obtain a high compactness of the unit, maintaining the masses at play as close as possible to the axis of rotation of the joint in order to achieve a high number of rpm and at the same time reduce vibration.

hi the embodiment represented in figure 5, the first seats 26 are defined along the external profile 25a and have an end which is open towards the outside. Pn the alternative embodiment represented in figure 6, on the other hand, the first seats 26 define a slot having an elongated shape which is closed to both ends. This particular embodiment allows to increase the stiffness of joint 25. Appropriately, the first revolving elements 27 are arranged on diametrically opposite sides of the inner ring 16 and the second revolving elements 29 are arranged on diametrically opposite sides of the rotor element 7.

The first revolving elements 27 are therefore integral in rotation to the inner ring 16 around the second axis 17 and are mobile in rotation with respect to it around the relative axis 27a. Similarly, the second revolving elements 29 are integral in rotation to the rotor element 7 around the first axis of rotation 8 and are mobile in rotation with respect to it around the relative axis 29a.

During the operation of the machine 1, therefore, the distance between each pair of revolving elements 27 and 29 remains unaltered, but their position along the relative seats 26, 28 varies.

As stated above, the revolving elements 27 and 29 are of the type of a sliding or roller bearing. In the first case, i.e. in the case of a sliding bearing, e.g. of the type of a bushing, the revolving elements 27 and 29 comprise an outer ring suitable for contacting the containment walls 26a, 28a of the relative seat 26, 28 and fit mobile in rotation on a relative inner ring integral to a pin defining the relative axis 27a, 29a of rotation. In the second case, i.e. in the case of a roller bearing, between the inner ring and the outer ring rollers or balls are placed which are coupled in a rotoidal manner to the rings themselves.

In both the above cases, the inner rings of the revolving elements 27 and 29 can be fixed integrally to the inner ring 16 or to the rotor element 7 which supports them via screw means or, alternatively, using a Seeger ring.

Advantageously, at least one of the revolving elements 27 and 29, preferably each of them, comprises at least one layer of an elastically yielding material (not visible in detail in the figures) which is suitable for dampening any vibrations which can occur during the rotation of the inner ring 16 and of the rotor element 7.

More specifically, the layer of elastically yielding material has a ring shape and is placed between the external surface of the relative revolving element 27, 29 and the relative axis 27a, 29a of rotation. This layer of elastically yielding material is therefore placed between the inner ring and the outer ring of the relative revolving element 27, 29, coaxially to it.

The operation of the present invention is as follows.

During the operation of machine 1, e.g. in the case in which it operates as a pump, oil is supplied under pressure along the supplying channel 5 while the oil is discharged along the discharge channel 6. More specifically, the oil under pressure enters through the cut 15a and, flowing through the pipes 15d, 15e, reaches the breakings 15b, 15c communicating with the respective chambers 11. Similarly, the oil which is discharged enters the breakings 16b, 16c and reaches the cut 16a flowing through the pipes 16d, 16e. The flowing direction of the working fluid in the supplying channel 5 and discharge channel 6 is indicated by the arrows shown in figure 1.

If you wish to control the timing of the machine 1, which is therefore of the variable timing type, the angular position of the distributor 4 is modified in order to anticipate or delay the injection phases into the chambers or the discharge phases with respect to the two dead points of the pistons 12. The phase may need to be corrected, as known to the experts in the field, due to the presence of hazardous spaces, variations in pressure, displacement, speed, etc. Moreover, by rotating the distributor 4 by 180° the motion of the rotor element 7 is inverted. As stated above, depending on whether the machine 1 operates as a pump or an engine, it may be required to axially move the distributor 4 along the first axis 8. For more information see the description in patent WO 03060321, contained herein as a reference.

Following the introduction of the working fluid, the pistons 12 move radially between an upper dead point and a lower dead point in the relative chambers 11. During the motion of the pistons 12 along the relative sliding directions 13, the pistons themselves move along a direction substantially perpendicular to the sliding direction itself in order to adapt to the geometrical conditions occurring during operation, so as to prevent misalignment with respect to the relative chambers 11.

Moreover, depending on the heat and lubricating conditions between their head 12a and the first locator surface 22a, the pistons 12 move along the first locator surface itself in order to position themselves in "colder" areas, i.e. in areas where there is a lubricant film and which ensure a correct hydraulic balancing. More specifically, as stated above, the areas of the first locator surface 22a which may be heated due to the friction with the head 12a of the relative piston 12 and which would not therefore allow the correct relative movement between the parts in contact, as well as a correct balancing of the forces, act as a hinge around which the piston itself moves. The pistons 12 are therefore arranged autonomously in correspondence to the "colder" areas of the first locator surface 22a, thus allowing the "hot" areas to cool down. In this way there is a substantially uniform exploitation of the first locator surface 22a, which ensures a correct hydraulic balancing of the forces acting on the pistons 12 as well as a correct lubrication of the parts in contact and mutually moving.

As described above, the movement of the pistons 12 with respect to the inner ring 16 along a direction transversal to their sliding direction 13 ensures that the point in which their force is discharged is misaligned with respect to the sliding directions themselves, thus producing a tangential component which brings the inner ring 16 in rotation around the second axis 17.

This rotation is transmitted to the rotor element 7 by the joint 25, which allows to maintain the synchronism between them. During the rotation of the inner ring 16, therefore, the first revolving elements 27 associated to it come into contact with a containment wall 26a of the relative first seats 26, thus exerting a torque on the joint 25, which in this way is made to rotate around a relative axis.

fn the same way, during the rotation of the joint 25 the second seats 28, defined on the same, come into contact by one of their containment walls 28a, with the outer surface of the relative second revolving elements 29, thus transmitting a torque to the rotor element 7 which supports them, which is thus made to rotate around the first axis 8.

As the first and the second axis 8 and 17 around which respectively the rotor element 7 and the inner ring 16 rotate keep their eccentricity, it follows that the axis of rotation of the joint 25 varies its position during the rotation of the inner ring and the rotor element themselves.

During the shift of the joint 25, the seats 26 and 28 move with respect to the revolving elements 27 and 29 fitted in them. More specifically, depending on the direction of rotation of the joint 25, the revolving elements 27 and 29 come into contact with their outer surface with one of the containment walls 26a, 28a of the relative seat 26, 28. The relative shift of the seats 26, 28 with respect to the revolving elements 27, 29 causes the rotation of the latter around their respective axes 27a, 29a due to the contact of their containment walls 26a, 28a with the relative outer surfaces.

It therefore follows that during the rotation of the joint 25 the revolving elements 27 and 29 roll on the containment walls 26a and 28a of the relative seats 26 and 28 around the respective axes 27a and 29a of rotation. More particularly, the area of contact between the revolving elements 27, 29 and the relative containment walls 26a, 28a corresponds, in theoretical conditions, to a line. There is therefore no mutual friction between the parts in contact.

During the rotation of the rotor element 7 the distributor 4 remains still in rotation due to the presence of the bearings 9 and 10, which support the alternate load due to the connection between the distributor itself and the chambers 11, as well as supporting the load due to any balancing imperfections. It has in fact been ascertained how the described invention achieves the proposed objects and in particular it is underlined how it allows the considerable reduction, compared to known devices, of the losses of energy due to friction between the mutually moving parts. In particular the use of a joint with relative seats inside which the respective revolving elements are housed, supported by the inner ring and the rotor element, means that there is no longer any relative friction between the moving parts, but only rolling contacts which, as is known, have much less friction.

The machine according to the invention is therefore considerable more silent than the machines of known type.

Moreover, the machine greatly facilitates the sizing and production of the connection joint between the inner ring and the rotor element compared to known machines. This is due to the fact that the rotational motion transmission between the inner ring and the distributor element occurs by contact between a cylindrical body and a flat surface and no longer between two flat surfaces. This ensures correct transmission of motion and forces even in the presence of imperfect planarity of the containment walls or lower working tolerances than those needed for the machines used until now.

The relative joint can therefore be sized in order to make it considerably lighter than the joints of the known machines, thus also reducing production costs and the weight of the inertial masses at play.

Again, the machine according to the invention, in use, allows to maintain a correct lubrication of the parts in contact and mutually moving.

Last but not least, the fastening means connecting the pistons to the inner ring offer better balancing than known machines of the hydraulic forces acting on the pistons themselves and more uniform wear of the parts in contact.