WO2005035988A1

WO2005035988A1 - A rotary hydraulic vane machine

Info

Publication number: WO2005035988A1
Application number: PCT/IB2004/003332
Authority: WO
Inventors: Vitangelo Pianaroli
Original assignee: Vitangelo Pianaroli
Priority date: 2003-10-14
Filing date: 2004-10-13
Publication date: 2005-04-21
Also published as: ITBO20030598A1

Abstract

In a hydraulic vane rotary machine includes, a case (11) defines a working chamber (3) delimited axially by a pair of heads (4a,4ó), with a rotor (5) mounted within the case (11) . The rotor (5) has a plurality of radial vanes (6) urged constantly against the inner surface (30) of the working chamber (3), so that rotating changeable volumes (7) are defined, which are cyclically set in communication with respective feeding conduits (8a,88a) and discharge conduits (8b,88b), A holes discoidal plate (90), is also mounted inside said working chamber (3) encircling the rotor and delimiting axially the rotating volumes (7) in cooperation with the first head (4a). Actuating means moves axially the discoidal plate (90) between two end configurations, for changing the volumetric delivery of the hydraulic machine.

Description

A ROTARY HYDRAULIC VANE MACHINE

FIELD OF THE INVENTION

The present invention relates to the technical field concerning reversible hydraulic machines, with particular reference to rotary vane machines.

BACKGROUND OF THE INVENTION

The rotary hydraulic machines operate with fluid at high working pressure and with volumetric outputs much higher with respect to reciprocating hydraulic machines, substantially due to the absence of alternating inertial forces which influences both the dimensions and the operation speed. The rotary machines are used a lot in the hydraulic field, because they allow better output rates than reciprocating machines, due to the high rotation speeds, because their weight and dimension are limited and because, at the delivery, the oscillations of their pressure are extremely limited with respect to the reciprocating ones.

The operation principle of the rotary hydraulic machines, which can have many different configurations, commonly including gears, lobes or vanes, is substantially based on the presence of the so-called "rotating volumes" which transfer the fluid from the aspiration input to the delivery output .

The fluid is swept under pressure, because the geometry of the rotation volumes changes during the fluid motion. The gear machines have one, sometimes more pairs of gears closed in a case. Rotation of the gears moves the liquid coming from the aspiration inlet to the delivery output.

The volumes, delimited between the two subsequent teeth of each gear and the walls of the case, are used for this purpose, while the contact between the teeth of the two gears prevents fluid reverse flow.

Due to their constructive characteristics, the gear machines are extremely compact and strong, and they are particularly suitable to process lubricants and liquids with a certain viscosity, to reduce as much as possible loss of fluid, which is a remarkable disadvantage of this type of machine.

The lobe machines, for example the "Roots" type ones, have two lobed rotors within a case.

The rotors complementary profiles engage one with the other.

Because a necessity to process considerable volumes of fluid requires, from a constructive point of view, rotors with a limited number of lobes (usually from two to six) . In the gear machine, motion to one gear to the other can be transmitter directly, the same as for any couple of meshing gears. Instead, in the lobe machines motion transmission cannot be direct because of the small number of lobes. In lobe machines, therefore, the motion from one lobe to the other is transmitted by means of a couple of meshing gears, which are respectively connected to the lobes and usually situated outside the case.

These machines can reach considerable high rotation speed and of the swept volume, while the most remarkable disadvantage derives from the excessive noise and from the significant loss of fluid between the lobed rotors, and between the rotors and the case.

The vane machines can be manufactured according to different constructive types, but, basically, they are equipped with one rotor, which is substantially offset with respect to the geometrical center of the cylindrical case. Rotation of the rotor makes the vanes slide on the inner surface of the case, so as to create, in the pump case, chambers having volumes which first increase (in suction) and then decrease (in delivery) , thus setting the fluid under pressure.

The cylindrical rotor, positioned eccentric with respect to the stationary case, has deep longitudinal grooves, usually radial, which receive freely corresponding vanes, and the vanes are radially driven constantly against the inner wall of the case.

The vanes are urged against the surface of the case by the centrifugal force and/or by possible supplementary systems, such as elastic means situated in the grooves. In this way, a sufficient volume is delivered also with low rotation speed, with an improved efficiency with respect to the solutions based on the centrifugal force only.

The vanes can have the classic rectangular, smoothed shape, or they can have more complex shapes, aimed at maximizing the tightness and reduce mechanical stresses and wear.

In particular, the vanes can have sliding blocks or rolls which, touching the inner surface of the case, reduce the mechanical stresses and wear.

In this configuration, rotation of the rotor imparts the vanes a predetermined centrifugal force, which makes them slide on the inner part of the case chamber, defining relative rotating volumes delimited radially by the housing and by the rotor and axially by the case head covers . The volumes move together with the vanes and their volume changes in relation to the angular position, due to the rotor offset with respect to the stator center.

The most severe drawback of the rotary machines, reversible and not, derives from the fact that it is extremely difficult to change the swept volume, in the pump mode operation, and/or the power torque at the output shaft, in the motor mode operation.

There are rotary vane machines which use elastic means acting radially on the outside of the vanes sliding ring, having variable configuration, to allow a prefixed swept volume variation, as an inversely proportional function of the operation pressure.

SUMMARY OF THE INVENTION The object of the present invention is to propose a hydraulic vane rotary machine, • which assures optimal swept volume, which can be varied within a wide adjustment range, maintaining a high volumetric efficiency. Another object of the present invention is to propose a rotary hydraulic machine, which allows best operation reversibility, assuring high reliability and versatility standards in any operation conditions.

A further object of the present invention is to propose a machine, which is particularly functional, extremely compact and strong, and needs only limited and rapid maintenance operations.

A still further object of the present invention is to propose a hydraulic machine, which can fulfill the so- called "torque converter" function.

The above mentioned objects are obtained, in accordance with the contents of the claims, by a hydraulic vane rotary machine, including: a case defining a substantially longitudinal working chamber with a corresponding inner surface,- a first head and a second head for axially delimiting said working chamber; a rotor mounted within said case and provided with a plurality of substantially radial longitudinal grooves; a series of vanes placed within said grooves and kept constantly in contact with the inner surface of said working chamber for defining corresponding rotating changeable volumes within said working chamber, said volumes being cyclically set in communication with respective feeding conduits and discharge conduits for a fluid of prefixed viscosity; the hydraulic machine being characterized by: at least one holes discoidal plate, situated within said working chamber and encircling tightly said rotor, with recesses made in the discoidal plate for receiving said vanes, so that said discoidal plate delimits axially said rotating volumes in cooperation with said first head; actuating means for changing the axial position of said discoidal plate with respect to said first head, between two end configurations, a first configuration and a second configuration, respectively corresponding to a maximum and a minimum volumetric delivery of said rotating volumes.

According to a second embodiment of the invention, the hydraulic vane rotary machine includes: a case, closed by a first end head and a second end head for defining a couple of substantially longitudinally extending working chambers, a first working chamber and a second working chamber, separated by a common head; a rotor mounted inside said case, said rotor having a plurality of substantially radial longitudinal grooves; a series of vanes placed within said longitudinal grooves of the rotor and urged constantly against the inner surface of the respective working chamber to define a first group and a second group of changeable rotating volumes delimited radially by said rotor and by the inner surface of the corresponding working chamber and axially by at least said end heads, said rotating volumes of each of said groups, first group and second group, being cyclically set in communication with respective feeding conduits and discharge conduits for a fluid of prefixed viscosity; and the hydraulic machine is characterized by: at least one holed discoidal plate, mounted within each working chamber, first working chamber and second working chamber, for encircling tightly said rotor and provided with a series of recesses for receiving the vanes, said discoidal plate delimiting axially the corresponding group of rotating volumes in cooperation with the respective end head; actuating means for changing the axial positions of said discoidal plates, first discoidal plate and second discoidal plate with respect to the corresponding end head, between two end configurations, first configuration and second configuration, respectively corresponding to a maximum and a minimum volumetric delivery of the relative group of rotating volumes.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristic features of the invention will be pointed out in the following description of some preferred, but not exclusive embodiments, with reference to the enclosed drawings, in which: Figure 1 shows a first embodiment of the proposed hydraulic vane rotary machine in a schematic, partially section view, taken along a plane orthogonal to the rotation axis; Figures 2, 2A, 2B are schematic section views, taken along the II-II indicated in Figure 1, of corresponding particularly significant operation configurations ; - Figure 3 is a schematic section view, taken along the III-III indicated in Figure 1; Figure 4 is a schematic section view, taken along the IV- IV indicated in Figure 2; Figure 5 is a schematic, partially section view, taken along an axial plane, of a particular mode of use of the rotary hydraulic machine, according to its first embodiment; Figure 6 is a schematic, partially section view, taken along an axial plane, of a particular mode of use of the proposed rotary hydraulic machine, according to its second embodiment; Figures 7A, 7B are views of corresponding technical - functional aspects of the hydraulic machine, proposed by the invention.

BEST MODES OF CARRYING OUT THE INVENTION

With reference to the above Figures, the general reference number 11 indicates a stationary case housing of the proposed hydraulic vane rotary machine, which defines a substantially longitudinal working chamber 3, delimited axially by a pair of heads, first 4a and second 4b.

A rotor 5, mounted inside the working chamber 3, has a plurality of longitudinal grooves 5a, substantially radial, which guide corresponding vanes 6, driven constantly, in known ways, against the inner surface 30 of the working chamber 3, so as to define rotating volumes 7 with variable volume. The rotating volumes 7 are radially delimited by the rotor 5 and by the inner surface 30; axially they are delimited by the first head 4a and by a discoidal plate 90, which is fastened to the case 11 with possibility of rotation relative thereto. The discoidal plate has a concentric hole having the same diameter as the rotor.

Advantageously, elastic means 14 can be situated in the longitudinal grooves 5a made in the rotor 5, to force the vanes 6 out from the center of the rotor into contact with inner surface 30 of the chamber 3. In a widely known way, the rotating volumes 7 are cyclically set in communication with relevant conduits, i.e. a feeding conduits 8a, 88a and a discharge conduits 8b, 88b, conducting a fluid flow having a prefixed viscosity, into and out from the chamber 3.

The conduits are made for example in the first head 4a (Figures 2, 2A, 2B, 3 - first embodiment) or in the case 11 (Figure 6 - second embodiment) .

The discoidal plate 90 surrounds the rotor 5, tightly embracing it, and has a plurality of substantially radial recesses 90a made along its internal border, which receive the vanes 6.

According to a preferred embodiment, the cross-section of the chamber 3 is substantially elliptical, with the rotor 5 mounted concentric therewith.

In particular, the rotor 5 has a circular cross section with a diameter substantially equal to the minor axis of the elliptic shape of the chamber 3.

According to a first embodiment (shown in Figures 2, 2A, 2B, 3), the discoidal plate 90 is advantageously fastened to the case 11, but rotation of the plate is possible with respect to the case. The case is movable axially by suitable actuating means.

The actuating means, by moving the case longitudinally, operate also the discoidal plate 90, moving it with respect to the first head 4a, between two end configurations, namely a first configuration A and a second configuration B, respectively corresponding to a maximum and a minimum volumetric delivery of the rotating volumes 7.

For this purpose, the case 11 is axially guided by the heads, first 4a and second 4b, and by an outer, substantially cylindrical frame 2, to which the two heads 4a, 4b are fastened.

The discoidal plate 90, which is situated inside the working chamber 3, is preferably motionless and radial- oriented with respect to the rotor 5.

In particular, the discoidal plate 90 is driven into rotation directly by the vanes 6, which engage with the relevant recesses 90a, made in the plate 90.

According to the first embodiment, the actuating means causing the axial motion of the case 11, and consequently of the discoidal plate 90, include a pair of chambers 71a, 71b, for example ring-like, extending longitudinally from each end of the case 11.

Suitable fluids under pressure enter the chambers 71a, 71b, in suitable step relation, so as to move the case 11 axially in one direction or the other.

The ring-like chambers 71a, 71b are defined by the spatial portions included between the outer frame 2, the heads 4a, 4b closing the working chamber 3 and the ends of the case 11.

The hydraulic machine includes' also a plurality of annular grooves 12, made in the case 11, communicating with the portion of the working chamber 3 situated between the discoidal plate 90 and the second head 4b, so as to prevent the fluid lost from the rotating volumes 7, from being set under pressure.

Advantageously, a plurality of drainage ducts 13a, 13b,

13c, 13d, made for example in the second head 4b, communicate with the portion of the working chamber 3 included between the discoidal plate 90 and the second head 4b and allow fluid flow coming from the rotating volumes 7 to go out through the second head 4b.

Figure 1 is a partially section view, taken along a plane orthogonal to the rotor 5, of a first embodiment of the proposed hydraulic machine, in which it is possible to see the working chamber 3, delimited radially by the elliptic case 11, and by the rotor 5, together with the rotating volumes 7, delimited by the vanes 6, constantly in contact against the inner surface 30 of the working chamber 3.

Figure 2 is a schematic, partially section view, taken along an axial plane, of the same machine in a working configuration, in which the swept volume of the rotating volumes 7 has a medium value. The axial section has been intentionally made in a region corresponding to the vanes 6 in a configuration of maximum extension with respect to the longitudinal grooves 5a made in the rotor 5, thus with the elastic means 14 at their maximum extension. Figure 2A shows the same axial section as in Figure 2A, with the discoidal plate 90 in the first end configuration A, characterized by the maximum swept volume of the rotating volumes 7, in which the annular chambers, first 71a and second 71b, have the maximum and minimum volumes, respectively.

Figure 2B shows the same axial section as Figures 2 and 2A , with the discoidal plate 90 in the second end configuration B, characterized by the minimum swept volume of the rotating volumes 7, in which the annular chambers, first 71a and second 71b, have the minimum and maximum volumes, respectively. Figure 3 shows schematically the proposed hydraulic machine according to its first embodiment, in a partially section view taken along an axial plane, orthogonal to the one used in Figures 2, 2A, 2B. The vanes 6 are in a configuration, in which they are entirely included within the longitudinal grooves 5a and consequently, the elastic means 14 are totally compressed.

It is possible to see in Figure 3 the discharge conduits 8b, 88b of the fluid, which goes out from the working chamber 3.

Figure 4 is a section view taken along a plane orthogonal to the axis of the rotor 5 and passing through an annular groove 12, which lets the fluid lost by the rotating volumes 7, and collected into the portion of the working chamber 3 included between the discoidal plate 90 and the second head 4b, to go out.

Figure 5 is a schematic, partially section view taken along an axial plane, of a particular use of the rotary hydraulic machine, according to its first embodiment, in which two mirror-like configurations of the above described structure are used, in order to obtain the so- called "torque converter" .

According to this embodiment, the hydraulic machine includes a case 110, defining a couple of working chambers, a first and a second chamber, arranged longitudinally one beside the other.

Each of the working chambers is axially delimited by a common head 40c and by a corresponding head, first 40a and second 40b, inside which a corresponding rotor 50, 500 is mounted. Each rotor 50, 500 includes a plurality of substantially radial longitudinal grooves, which guide corresponding vanes 60, 600, kept continuously in contact with the inner surface of the respective working chamber, to define a first group and a second group of rotating variable volumes .

The rotating volumes of each group are delimited radially by the related rotor 50, 500 and by the inner surface of the corresponding working chamber, and axially by the relevant terminal ends 40a, 40b and by a corresponding discoidal plate 900a, 900b, fastened to the case 110 with possibility of rotation.

Each group of rotating volumes is cyclically set in communication with respective conduits 80a, 80b, 800a, 800b for feeding and discharging a corresponding fluid with a selected viscosity, into and out of the working chamber.

Each discoidal plate 900a, 900b encircles tightly the corresponding rotor 50, 500 and has pluralities of substantially radial longitudinal recesses, which receive corresponding vanes 60, 600.

Suitable actuating means operate axially the discoidal plates, first 900a and second 900b, with respect to the corresponding end head 40a, 40b, between end configurations, namely a first end configuration and a second end configuration, respectively corresponding to a maximum and a minimum swept volume of the relevant group of rotating volumes.

Advantageously, the case 110 is removably constrained to each of the discoidal plates 900a, 900b and is operated to translate axially by actuating means, including substantially a pair of chambers 710a, 710b, for example annular chambers, arranged longitudinally at each end of the case 110 and supplied, in suitable phase relation, with corresponding fluids under pressure.

In this configuration of the proposed hydraulic machine, it is possible to convert the mechanical torque C acting on the first rotor 50, for example a constant torque, into a variable mechanical torque C*, whose value changes at the axis of the second rotor 500, by simply acting on the case 110, which is capable of changing, in suitable synchrony, the configurations of the discoidal plates 900a, 900b with respect to the corresponding end heads 40a, 40b.

The reduction of the rotating volumes connected to the first rotor 50 corresponds to an increase of the volumetric delivery of the rotating volumes of the second rotor 500, with a relative increase of the mechanical torque C* value at the axis of the second rotor 500.

Consequently, the increase of the rotating volumes connected to the first rotor 50 corresponds to reduction of the volumetric delivery of the rotating volumes connected to the second rotor 500, with reduction of the mechanical torque C* value at the axis of the second rotor 500.

Figure 6 is a schematic, fragmentary section view taken along an axial plane, of the proposed hydraulic machine according to a second embodiment and in a working configuration characterized by an intermediate delivery of the rotating volumes 7.

With respect to the first embodiment, the discoidal plate 90 is still constrained to the case 11, with possible rotation, but in this case, the actuating means operate the rotor 5 into an axial translation with respect to the discoidal plate 90.

In this regard, the rotor 5 is advantageously connected to the corresponding axis 500 by a splined coupling. According to the second embodiment, the actuating means include a pair of chambers 171a, 171b, each of which is delimited longitudinally by at least the corresponding head 4a, 4b. The chambers 171a, 171b which are entered, in suitable step relation, by corresponding fluids under pressure, operating the rotor 5 and the relative heads 4a, 4b axially with respect to the case 11.

The heads 4a, 4b according to the present embodiment, are axially linked to each other, so that an axial excursion of the one head corresponds to an equal excursion of the other.

According to the embodiments shown in Figures 1 - 6, only one vane 6, 60, 600 is placed in each longitudinal groove of the rotor 5, 50, 500.

It is possible to propose variants, according to which two or more vanes are placed into each groove, as illustrated in Figures 7A, 7B, which show, respectively, for example two vanes 66, 166 and three vanes 66, 166, 266.

These variants optimize the technical-functional aspect deriving from the constant contact with the inner surface of the working chamber 3.

It is understood from the proposed embodiments of the hydraulic machine proposed by the present invention, that it is possible to change easily the swept volume of the rotating volumes by acting suitably on the relative configuration of the discoidal plate, thus allowing the optimal variation of the fluid flow, without influencing in any way the volumetric efficiency of the hydraulic machine .

During the rotor rotation, the vanes are guided by the longitudinal grooves made in the rotor, as well as by the longitudinal grooves made in the discoidal plate, which leads to the motion of the vanes being stabilized.

The possibility to move the case, or the rotor, into axial translation, by injecting fluid under pressure into the relevant, preferably annular, chambers assures high reliability and versatility standards in any operation conditions .

Moreover, the limited percentage of the fluid lost in the region corresponding to the peripheral portion of the discoidal plate, in case of fluid with high viscosity, allows a determined lubrication of the coupling section with the case.

From what above, it is easily understood that the hydraulic machine proposed by the present invention is particularly functional, extremely compact and strong and needs only limited and rapid maintenance operations.

It is understood that the proposed invention has been described, with reference to the enclosed figures, as a mere, non-limiting example. Therefore, all possible changes and variants of the invention remain within the protective scope of the present technical solution, as described above and claimed below.

Claims

1. A hydraulic vane rotary machine, including: a case (11) defining a substantially longitudinal working chamber (3) with a corresponding inner surface,- a first head (4a) and a second head (4b) for axially delimiting said working chamber (3) ; a rotor (5) mounted within said case (11) and provided with a plurality of substantially radial longitudinal grooves (5a) ,- a series of vanes (6) placed within said grooves and kept constantly in contact with the inner surface (30) of said working chamber (3) for defining corresponding rotating changeable volumes (7) within said working chamber (3) , said volumes (7) being cyclically set in communication with respective feeding conduits (8a, 88a) and discharge conduits (8b, 88b) for a fluid of prefixed viscosity; the hydraulic machine being characterized by: at least one holes discoidal plate (90) , situated within said working chamber (3) and encircling tightly said rotor (5) , with recesses made in the discoidal plate for receiving said vanes (6) , so that said discoidal plate (90) delimits axially said rotating volumes (7) in cooperation with said first head (4a) ; actuating means for changing the axial position of said discoidal plate (90) with respect to said first head (4a) , between two end configurations, a first configuration (A) and a second configuration (B) , respectively corresponding to a maximum and a minimum volumetric delivery of said rotating volumes (7) .

2. A hydraulic machine as claimed in claim 1, characterized by a series of longitudinal recesses (90a) , substantially radial, made in said discoidal plate (90) and receiving said vanes (6) , coupling therewith.

3. A hydraulic machine as claimed in claim 2, characterized in that said discoidal plate (90) is situated in said working chamber (3) in fixed radial configuration with respect to the rotor (5) .

4. A hydraulic machine as claimed in claim 3, characterized in that said discoidal plate (90) is driven into rotation by said vanes (6) .

5. A hydraulic machine as claimed in one of the claims from 1 to 4, characterized in that said discoidal plate (90) is constrained to said case (11) with possibility of rotation; and in that said rotor (5) is moved axially with respect to said discoidal plate (90) , by said actuating means.

6. A hydraulic machine as claimed in claim 5, characterized in that said rotor (5) is coupled to the corresponding axis (500) by a splined coupling.

7. A hydraulic machine as claimed in claim 5 or 6, characterized in that said actuating means include a pair of chambers (171a, 171b) , each of which is delimited longitudinally by at least the corresponding head (4a, 4b) and is supplied, in suitable step relation, with corresponding fluids under pressure to move said rotor (5) and said heads (4a, 4b) axially with respect to said case (11), said heads (4a, 4b) being linked to each other.

8. A hydraulic machine as claimed in one of the claims from 1 to 4, characterized in that said discoidal plate (90) is constrained to said case (11) with possibility of rotation; and in that said case (11) is moved axially by said actuating means.

9. A hydraulic machine as claimed in claim 8, characterized in that said actuating means include a couple of chambers (71a, 71b), situated at each end of said case (11) and supplied, in suitable step relation, with corresponding fluids under pressure, which move said case (11) axially with respect to said rotor (5) .

10. A hydraulic machine as claimed in one of the previous claims, characterized in that it includes a plurality of annular grooves (12) , made in said case (11) , communicating with the portion of said working chamber (3) included between said discoidal plate (90) and said second head (4b) , so as to prevent the fluid, lost by said rotating volumes (7), from being set under pressure.

11. A hydraulic machine as claimed in claim 10, characterized in that it includes at least one drainage duct (13a, 13b, 13c, 13d) , communicating with said portion of the working chamber (3) included between said discoidal plate (90) and said second head (4b) , and allowing the fluid lost by said rotating volumes (7) to exit through the second head (4b) .

12. A hydraulic machine as claimed in one of the previous claims, characterized in that it includes elastic means (14) , situated inside said longitudinal grooves (5a) and biasing the vanes (6) constantly against the lateral surface (30) of said working chamber (3) .

13. A hydraulic machine as claimed in one of the previous claims, characterized in that the axial section of the working chamber (3) is substantially elliptical

14. A hydraulic machine as claimed in claim 13, characterized in that said rotor (5) is mounted inside said working chamber (3), substantially coaxial therewith.

15. A hydraulic machine as claimed in claim 13 or 14, characterized in that the diameter of a circular section of the rotor (5) is substantially equal to the minor axis of the elliptic shape of said working chamber (3) .

16. A hydraulic vane rotary machine, including: a case (110) , closed by a first end head (40a) and a second end head (40b) for defining a couple of substantially longitudinally extending working chambers, a first working chamber and a second working chamber, separated by a common head (40c) ; a rotor (50,500) mounted inside said case (110), said rotor (5) having a plurality of substantially radial longitudinal grooves,- a series of vanes (60,600) placed within said longitudinal grooves of the rotor and urged constantly against the inner surface of the respective working chamber to define a first group and a second group of changeable rotating volumes delimited radially by said rotor (50,500) and by the inner surface of the corresponding working chamber and axially by at least said end heads (40a, 40b), said rotating volumes of each of said groups, first group and second group, being cyclically set in communication with respective feeding conduits (80a, 80b, 800a, 800b) and discharge conduits for a fluid of prefixed viscosity; the hydraulic machine being characterized by.- at least one holed discoidal plate (900a, 900b), mounted within each working chamber, first working chamber and second working chamber, for encircling tightly said rotor (50.500) and provided with a series of recesses for receiving the vanes (60,600), said discoidal plate (900a, 900b) delimiting axially the corresponding group of rotating volumes in cooperation with the respective end head (40a, 40b); actuating means for changing the axial positions of said discoidal plates, first discoidal plate (900a) and second discoidal plate (900b) with respect to the corresponding end head (40a, 40b), between two end configurations, first configuration and second configuration, respectively corresponding to a maximum and a minimum volumetric delivery of the relative group of rotating volumes.

17. A hydraulic machine as claimed in claim 16, characterized in that said case (110) is removably constrained to each of said discoidal plate (900a, 900b); said case (110) being moved axially by said actuating means; and in that said actuating means include a pair of chambers (710a, 710b), extending longitudinally form each end of said case (110) , and supplied, in suitable step relation, with corresponding fluids under pressure for moving axially said case (110) .