Hydrostatic rotation machine with radial pistons and optimized distribution

Abstract

Hydrostatic rotation machine comprising: – an internal element (1) and an external element (2) rotating relative to each other around an axis of rotation (R); – a hydraulic distributor (18). The hydraulic distributor (18) comprises: – an insertion section (28) extending axially between a section of smaller diameter (29) and a section of larger diameter (30), with a first synchronization surface (31); – fluid distribution conduits (44) which each comprise an end segment (24) opening transversely to the first synchronization surface (31), and obliquely relative to the axis of rotation (R).The cylinder block (10) comprises: – a receiving section (32) complementary to the insertion section (28) of the hydraulic distributor (18); – fluid diffusion conduits (49) which each comprise an end segment (36) opening transversely to the second synchronization surface (35), and obliquely relative to the axis of rotation (R). Figure for the abstract: Fig.1A.

Description

Title of the invention: Hydrostatic rotation machine with radial pistons and optimized distribution Technical field

[0001] The invention relates to the field of mechanics and hydraulics and more particularly relates to a hydrostatic rotation machine.

[0002] Hydrostatic rotation machines are rotating machines comprising a stator coupled with a rotor which is generally connected to a rotating drive element such as a wheel, a pinion or any transmission device.

[0003] Such a hydrostatic machine can be used as a hydraulic motor. It is then powered by a pressurized hydraulic fluid and in response drives the rotating drive element.

[0004] The hydrostatic machine can also be used as a hydraulic pump. It then receives a torque transmitted by the rotating drive element and compresses the hydraulic fluid in response. PRIOR ART

[0005] Patent application WO2020008145 describes a hydrostatic rotation machine comprising: - an internal element and an external element coaxial and mounted to rotate relative to each other around an axis of rotation, one of these elements being a rotor and the other of these elements being a stator, the external element comprising a circumferential internal cam path, the internal element comprising a cylinder block having radial cylinders provided with radially movable pistons distributed circumferentially, the cylinder block being arranged in the center of the cam path, the pistons being adapted to cooperate with the cam path during rotation of the rotor relative to the stator; - a hydraulic distributor adapted to selectively connect the cylinders to a hydraulic circuit, thanks to a synchronization junction forming a rotating coupling between the rotor and the stator.

[0006] Although this hydrostatic machine has advantages in several areas, it can still be improved with regard to the optimization of its dimensioning and its compactness. Statement of the invention

[0007] The invention aims to improve the hydrostatic rotation machines of the prior art.

[0008] To this end, the invention relates to a hydrostatic rotation machine comprising: - an internal element and an external element coaxial and mounted to rotate relative to each other around an axis of rotation, one of these elements being a rotor and the other of these elements being a stator, the external element comprising a circumferential internal cam path, the internal element comprising a cylinder block having radial cylinders provided with radially movable pistons distributed circumferentially, the cylinder block being arranged in the center of the cam path, the pistons being adapted to cooperate with the cam path during rotation of the rotor relative to the stator; - a hydraulic distributor adapted to selectively connect the cylinders to a hydraulic circuit, thanks to a synchronization junction forming a rotating coupling between the rotor and the stator.

[0009] In addition, the hydraulic distributor comprises: - an insertion section extending axially between a section of smaller diameter and a section of larger diameter, this insertion section having a first synchronization surface extending between the contour of the section of smaller diameter and the contour of the section of larger diameter; - fluid distribution conduits which each comprise an end segment opening transversely to the first synchronization surface, and obliquely relative to the axis of rotation.

[0010] In addition, the cylinder block comprises: - a receiving section complementary to the insertion section of the hydraulic distributor, this receiving section having a second synchronization surface complementary to the first synchronization surface of the hydraulic distributor, said synchronization junction being formed from the association of the first synchronization surface and the second synchronization surface; - fluid diffusion conduits which each comprise an end segment opening transversely to the second synchronization surface, and obliquely relative to the axis of rotation.

[0011] According to the invention, the hydrostatic machine simultaneously presents a gain in compactness and an optimization of its dimensioning.

[0012] The coupling of the insertion section of the hydraulic distributor and the receiving section of the cylinder block, at the synchronization junction, makes it possible to ensure the fluid distribution function for the hydrostatic machine, consisting of cyclically matching each cylinder with the high pressure or low pressure side of the fluid circuit. This distribution function is here carried out with forces produced by the hydraulic fluid, and which are exerted at the synchronization junction. These forces are oriented obliquely, thanks to the characteristics of the synchronization surfaces and the corresponding conduits, and have thus an axial component and a radial component. Given the arrangement of the hydrostatic rotating machine with its radial pistons, the radial components of these forces are exerted and compensated only at the cylinder block, without transmission of this component to other elements. Thus, part of the force generated by the pressure of the hydraulic fluid and necessary for the transmission of energy is not applied to the bearings coupling the rotor and the stator, but is instead applied to an element which can be made from a single piece, and whose dimensioning can be easily planned to hold these constraints within its material.

[0013] For example, for a hydraulic motor working under a pressure of the order of 400 bars, the force generated at the level of a distribution duct, at the moment when it is cyclically blocked by the second synchronization surface, is of the order of 35 kN. In the case of a distribution duct creating a force at 45° relative to the axis of rotation, the axial component of this force represents approximately 2 / 3 of the total force, and it is this force which is applied axially to other elements, and in particular to the bearings which are provided to withstand the forces, depending on the bearing assembly provided for the rotational connection of the rotor and the stator around the axis of rotation. In this illustrative example, a reduction in the force applied to these bearings of the order of 10 kN is obtained. In most bearing arrangements, only one of the bearings carries the bulk of this axial force, and such a 10 kN reduction is very significant.

[0014] The first consequence of the invention impacts the dimensioning of the bearings which can thus be dimensioned in a compact manner, and can be selected from a wider choice of technologies, while maintaining the same performance for the hydrostatic machine, with a consequent reduction in the cost and size of the bearings and therefore of the hydrostatic machine as a whole, where the prior art generally requires bulky and expensive roller bearings according to complex assemblies, adapted to high axial loads.

[0015] The overall size, and in particular the axial size, of the hydraulic distributor is also reduced to the extent that the axial reduction of the forces linked to the fluid pressure also makes it possible to reduce the force that the hydraulic distributor must exert against the cylinder block in order to maintain the synchronization junction (the "cylinder" function of the hydraulic distributor). The hydraulic distributor can thus also be dimensioned in a more compact and simplified manner.

[0016] The second consequence of the invention concerns the simplification of the rib chains thanks to the arrangement of the synchronization junction, also allowing a gain in compactness and reliability.

[0017] The gain in compactness is further reinforced in the axial dimension by the fact that sections of the hydraulic distributor and the cylinder block are axially embedded.

[0018] The arrangement of the synchronization junction also makes it possible to implement swivel functions between the internal element and the external element.

[0019] The invention thus makes it possible either to optimize the dimensioning of several components, and therefore to gain in compactness and cost over the entire hydrostatic machine, or to oversize the machine at constant compactness and cost and thus to designate it for other applications, for example heavier applications, at higher speed, or requiring a longer service life. A simplification of the construction, permitted by the arrangement of the synchronization junction, also allows gains in reliability and maintainability.

[0020] The invention also allows for simpler manufacturing processes and further reduces manufacturing costs.

[0021] The hydrostatic rotation machine according to the invention may include the following additional characteristics, alone or in combination:

[0022] - the end segments of the distribution conduits form an angle sen possibly between 20° and 60°, and preferably substantially equal to 45°, relative to the axis of rotation;

[0023] - the end segments of the diffusion ducts form a substantially between 20° and 60°, and preferably substantially equal to 45°, relative to the axis of rotation;

[0024] - the distribution conduits each open through a distribution orifice onto the first synchronization surface, the normal to each distribution orifice forming an angle substantially between 20° and 60°, and preferably substantially equal to 45°, relative to the axis of rotation R; and the diffusion conduits each open through diffusion orifices onto the second synchronization surface, the normal to each diffusion orifice forming an angle substantially between 20° and 60°, and preferably substantially equal to 45°, relative to the axis of rotation;

[0025] - the angle formed by the normal to each distribution orifice relative to the axis of rotation, is preferably identical to the angle formed by the normal to each diffusion orifice relative to the axis of rotation;

[0026] - each distribution orifice and each diffusion orifice extends in a plane which forms an angle substantially between 20° and 60°, and preferably substantially equal to 45°, with the axis of rotation;

[0027] - the first synchronization surface and the second synchronization surface are portions of spherical surfaces;

[0028] - when the hydraulic distributor and the cylinder block are in a position angular where a distribution orifice is opposite a diffusion orifice, the end segment of the corresponding distribution duct and the end segment of the corresponding diffusion duct are aligned;

[0029] - the external element comprises a tubular housing which carries the cam path and in in which bearings are mounted ensuring the rotating assembly of the internal element and the external element relative to each other;

[0030] - one of said bearings is substantially axially aligned with the syn junction chronology;

[0031] - the cylinder block has two collars arranged on either side of the cylinders, with a bearing mounted between each collar and the outer member;

[0032] - one of said bearings is substantially arranged in the direction in which extends each end segment of the distribution ducts;

[0033] - the hydraulic distributor comprises rectilinear distribution conduits between a central chamber and the first synchronization surface;

[0034] - the hydraulic distributor comprises distribution conduits between a peripheral chamber and the first synchronization surface, these distribution conduits comprising: a first rectilinear segment parallel to the axis of rotation and opening into the peripheral chamber; and said end segment which is oblique;

[0035] - the diffusion ducts of the cylinder block are rectilinear between each cylinder and the second synchronization surface;

[0036] - the external element comprises a distribution base inserted into the distributor hydraulic, the hydraulic distributor being axially movable on the distribution base and the hydraulic distributor being coupled in rotation with the distribution base;

[0037] - the hydraulic distributor has two chambers delimited by a seal circular end seal and by a circular base seal arranged between the distribution base and the hydraulic distributor, the circular end seal being of smaller diameter than the circular base seal;

[0038] - the hydraulic distributor is connected by a ball joint to the distributor base tribute;

[0039] - the external element comprises in a single piece said tubular housing, said base distribution and a first cover connecting the tubular housing to the distribution base;

[0040] - the synchronization junction has a border opening on the one hand into the external element and on the other hand in an axial chamber of the internal element;

[0041] - the internal element comprises a lubrication duct connecting the axial chamber to an area opposite a seal to be lubricated, integral with the external element. PRESENTATION OF FIGURES

[0042] Other characteristics and advantages of the invention will emerge from the non-limiting description which follows, with reference to the appended drawings in which:

[0043] - [Fig. 1 A] is an axial sectional view of a hydrostatic rotation machine according to the invention;

[0044] - [Fig.lB] is a view similar to [Fig.lA], for another angular position of the rotor relative to stator;

[0045] - [Fig.2] is a detailed view of an axial section of the hydrostatic machine, showing the hydraulic distributor in another angular position;

[0046] - [Fig.3] is a perspective view of the hydraulic distributor of the hy machine drostatic;

[0047] - [Fig.4] is a perspective view of the cylinder block of the hydro machine static;

[0048] - [Fig.5] is a schematic detail view of [Fig.1A],;

[0049] - [Fig.6] is a front view of the hydraulic distributor of the hydro machine static.

[0050] Elements similar and common to the various embodiments bear the same reference numbers in the figures. DETAILED DESCRIPTION

[0051] [Fig.lA] illustrates a hydrostatic rotation machine according to the invention, seen in section along a plane extending along its axis of rotation R. [Fig.lB] illustrates the hydrostatic machine according to the same section, for a different angular position of the rotor relative to the stator.

[0052] This hydrostatic machine is either a hydraulic motor driving an element in rotation from a pressurized hydraulic fluid, or a hydraulic pump adapted to put a pressurized hydraulic fluid from the rotation of an element.

[0053] The hydrostatic rotation machine comprises an internal element 1 and an external element 2 which are mounted rotating relative to each other around the axis of rotation R by bearings 14, 15.

[0054] In the present illustrative example, the hydrostatic machine is a hydraulic motor and the internal element 1 is integral with a drive element which here consists of a splined shaft 3.

[0055] Among the inner element 1 and the outer element 2, one of these elements is a rotor while the other of these elements is a stator. In the present example, the outer element 2 is a stator and is connected to a frame such as a fixed structure or one mounted on a vehicle, while the inner element 1 is a rotor and the splined shaft 3 is connected by example to a wheel or a pinion.

[0056] The external element 2 comprises a housing 5, which here has a tubular shape, with a first cover 6 which hermetically closes one of the openings (on the right of [Fig.lA]) of this tubular housing 5, and a second cover 7 which hermetically closes the opposite opening (on the left of [Fig.lA]).

[0057] The external element 2 is furthermore integral with a cam path 8 characteristic of hydrostatic machines with radial pistons. In a known manner, this cam path 8 is a circumferential shape internal to the wall of the housing 5, with a path formed of hollows and bumps, constituting a cyclic path with a succession of increasing and decreasing radii synchronized with the entry and exit movement of the radial pistons.

[0058] This cam path 8 may for example be machined directly on an internal face of the external element 2, for example machined directly on an internal face of the element 5. However, as illustrated in the figures, the present example preferably implements a cam path 8 carried by a cam ring 9 like that described in the patent application WO2020008145. This cam ring 9 is inserted into the housing 5 of the external element 2, on an internal surface and is stopped in rotation by any means.

[0059] The internal element 1 comprises a cylinder block 10 which is also specific to hydrostatic machines with radial pistons. This cylinder block 10 is provided with cylinders 11 in which radially movable pistons 12 are mounted.

[0060] In a known manner, the cylinders 11 are radial cylinders which extend over the entire circumference of the cylinder block 10, angularly distributed in a regular manner around the axis of rotation R, and the pistons 12 each comprise, on their end facing the cam path 8, a roller 13 allowing rolling without sliding on the cam path 8.

[0061] The cam paths for hydrostatic machines, the cooperation with the radial pistons, and the synchronization methods by selectively connecting the cylinders with the hydraulic fluid circuit, are also known and will not be described in more detail here.

[0062] The internal element 1 and the external element 2 are mounted rotating relative to each other thanks, in this example, to a first bearing 14 and a second bearing 15 directly mounted between the internal element 1 and the external element 2. In addition to the cam ring 9, the tubular housing 5 carries these bearings 14, 15. The example of the drawings illustrates two possible assemblies of the bearings 14, 15 in the housing 5: a direct assembly of the bearing with its external ring in contact with the housing 5 (this is the case of the first bearing 14); and an assembly of the bearing in the housing with an intermediate support ring (this is the case of the second bearing 15), and in the present example this support ring is part of the second cover 7.

[0063] The cylinder block 10 comprises two collars 16, 17 arranged on either side of the cylinders 11, with a bearing 14, 15 mounted between each collar 16, 17 and the external element 2, the internal ring of each bearing 14, 15 being directly mounted on the corresponding collar 16, 17.

[0064] A simple bearing assembly generating reduced dimension chains is thus obtained, with the cam ring 9 mounted in the housing 5 and the bearings 14, 15 arranged on either side of this cam ring 9, providing a direct interface between the internal element 1 and the external element 2.

[0065] The hydrostatic machine further comprises means for distributing and synchronizing the hydraulic fluid. These means comprise a hydraulic distributor 18 and a distribution base 4.

[0066] The distribution base 4 comprises a fluid inlet 19 and a fluid outlet 20 (partially visible in the sectional view of [Fig.lA], and visible in [Fig.lB]) which are connected in a conventional manner to the high pressure and low pressure portions of a hydraulic circuit. The hydrostatic machine also comprises a drain.

[0067] The distribution base 4 is integral with the external element 2. In this example, the distribution base 4 is integral with the first cover 6.

[0068] The hydraulic distributor 18 is mounted on the distribution base 4, being axially movable relative to the latter, the two parts being coupled in rotation. Housings 26 are made opposite each other in the distribution base 4 and in the hydraulic distributor 18 and allow rotational coupling by means of pins, while allowing axial sliding, and can also house springs to exert pressure from the hydraulic distributor 18 against the internal element 1.

[0069] The hydraulic distributor 18 comprises a central chamber 22 and a peripheral chamber 23 each connected to the fluid inlets 19 or fluid outlet 20. [Fig. 1B] illustrates the connection of the chambers 22, 23 to the fluid inlets / outlets 19, 20 according to the present example.

[0070] Seals allow the hermetic partitioning of the chambers 22, 23, while allowing the axial movement of the hydraulic distributor 18 on the distribution base 4. These seals here comprise a circular end seal 25 and a circular base seal 27.

[0071] [Fig.2] is a partial view of [Fig.1A], according to another angular position showing the connection of the peripheral chamber 23 of the hydraulic distributor 18.

[0072] In a known manner, the two seals 25, 27 have different diameters in order to create an axial cylinder function for the hydraulic distributor 18. This axial cylinder function makes it possible to hold the hydraulic distributor 18 against the internal element 1, by opposing the forces generated during the implementation of the synchronization, that is to say the selective pressurization of the cylinders 11. The distribution base 4 thus comprises an axial mouth 21 carrying the end circular seal 25 while the base circular seal 27 is arranged at the base of the distribution base 4. The diameter of the end circular seal 25 is less than the base circular seal 27 according to a proportion determining the force desired for the axial cylinder function.

[0073] The cylinder thus created by the hydraulic distributor 18 has the effect of countering the repulsion force exerted in the interface (the synchronization junction 37) between the hydraulic distributor 18 and the cylinder block 10.

[0074] The hydraulic distributor 18 further comprises an insertion section 28 which extends axially between a section of smaller diameter 29 and a section of larger diameter 30. In other words, the insertion section 28 is a slice of material which extends between a plane bearing the reference 29 in [Fig.lA], and a plane bearing the reference 30 in [Fig.lA].

[0075] [Fig. 3] is a perspective view of the hydraulic distributor 18 alone. The dis hydraulic feeder 18 being a part of revolution, the two sections 29, 30 each define a circular shape whose contour is a circle. The section with a smaller diameter 29 thus has a contour 42 which is a circle, and the section with a larger diameter 30 has a contour 43 which is a circle. The diameter of the contour 42 is thus smaller than the diameter of the contour 43.

[0076] The insertion section 28 of the hydraulic distributor 18 has a first synchronization surface 31 which extends obliquely between the contour 42 of the lower diameter section 29 and the contour 43 of the upper diameter section 30. The first synchronization surface extends obliquely to the extent that it extends non-parallel and non-perpendicular to the axis of rotation R.

[0077] In the present example, the first synchronization surface 31 is a spherical zone defined as the portion of the surface of a sphere passing through the two contours 42, 43, and cut by the two sections 29, 30.

[0078] In the first illustrative example, the radius of this sphere is of the order of 4 cm.

[0079] The central chamber 22 and the peripheral chamber 23 are each connected to the first synchronization surface 31 by fluid distribution conduits 44 which each comprise an end segment 24 opening transversely to the first synchronization surface 31 and obliquely relative to the axis of rotation R. In the present example, these end segments 24 form an angle a of between 20° and 60° with the axis of rotation R, and preferably 45 “as illustrated. In other words, the longitudinal axis 54 of each end segment 24 intersects the axis of rotation R and forms with it the angle a (it is the internal angle which is considered here).

[0080] In the present example, more precisely, each end segment 24 opens into the second synchronization surface 35 while being substantially orthogonal to a plane tangent to this surface.

[0081] In the present example, the distribution ducts 44 which connect the central chamber 22 to the first synchronization surface 31 are rectilinear. The end segment 24 of each is therefore in the extension of the rest of the distribution duct 44, and the entire distribution duct 44 forms an angle, which is 45° in this example, with the axis of rotation R.

[0082] The arrangement according to the invention makes it possible to obtain a connection between the chambers 22, 23 of the hydraulic distributor 18 and the cylinders 11 which can be significantly shortened, and which also contributes to reducing pressure losses.

[0083] In the present example also, the distribution conduits 44 which connect the peripheral chamber 23 to the first synchronization surface 31 each comprise: a first segment 45 rectilinear and parallel to the axis of rotation R, this first segment opening into the peripheral chamber 23; and said end segment 24 which is oblique, with its angle of 45° in this example, relative to the axis of rotation R.

[0084] In addition, the distribution conduits 44 each open through a distribution orifice 46 onto the first synchronization surface 31 (see [Fig. 3]). These distribution orifices 46 are oriented on the first synchronization surface 31 so that the normal to each distribution orifice 46, which intersects the axis of rotation R, forms an angle substantially between 20° and 60°, and preferably 45°, relative to the axis of rotation R.

[0085] The first synchronization surface 31 is intended to cooperate with the internal element 1 as part of the synchronization function aimed at selectively distributing the hydraulic fluid by taking advantage of the rotation of the rotor relative to the stator. The cylinder block 10 here cooperates directly with the first synchronization surface 31, without requiring an interface by other components of the internal element 1.

[0086] The cylinder block 10 comprises a receiving section 32 which is complementary to the insertion section 28 of the hydraulic distributor 18. The receiving section 32 extends axially between a section of smaller diameter 33 and a section of larger diameter 34.

[0087] [Fig.4] is a perspective view of the cylinder block 10 alone. The lower diameter section 33 thus has a cavity with a contour 47 which is a circle, and the upper diameter section 34 has a cavity with a contour 48 which is a circle. The diameter of the contour 47 is thus less than the diameter of the contour 48.

[0088] The receiving section 32 of the cylinder block 10 has a second surface of synchronization surface 35 which extends obliquely between the contour 47 and the contour 48 of the cavity of the cylinder block. The second synchronization surface 35 extends obliquely to the extent that it extends non-parallel and non-perpendicular to the axis of rotation R.

[0089] The second synchronization surface 35 is complementary to the first synchronization surface 31, and it therefore has in this example the shape of a spherical zone, that is to say a portion of the surface of a sphere passing through the two contours 47, 48, and cut by the two sections 33, 34.

[0090] With reference to figures 1A and 1B, when the hydrostatic machine is in operating condition, the first synchronization surface 31 is urged towards the second synchronization surface 35, the association of these two synchronization surfaces 31, 35 forming a synchronization junction 37 in which the hydraulic fluid will be selectively distributed between two elements with a relative rotation.

[0091] The cylinder block 10 further comprises diffusion ducts 49 for the hydraulic fluid. These diffusion ducts 49 connect the second synchronization surface 35 to the cylinders 11 for the exchange of fluid in relation to the movement of the pistons 12. The diffusion ducts 49 each comprise an end segment 36 opening transversely to the second synchronization surface 35 and obliquely relative to the axis of rotation R. In the present example, these end segments 36 form an angle α of between 20° and 60° with the axis of rotation R, and preferably 45° as illustrated. In other words, the longitudinal axis 55 of each end segment 36 intersects the axis of rotation R and forms the angle α with it (it is the internal angle which is considered here).

[0092] In the present example, more precisely, each end segment 36 opens into the second synchronization surface 35 while being substantially orthogonal to a plane tangent to this surface.

[0093] In the present example, the diffusion ducts 49 are rectilinear. The end segment 36 of each is therefore in the extension of the rest of the diffusion duct 49, and the entire diffusion duct 49 forms an angle, which is 45° in this example, with the axis of rotation R.

[0094] In addition, the diffusion conduits 49 each open through a diffusion orifice 50 onto the second synchronization surface 35 (see [Fig. 4]). These diffusion orifices 50 are oriented on the second synchronization surface 35 so that the normal to each diffusion orifice 50, which intersects the axis of rotation R, forms an angle substantially between 20° and 60°, and preferably 45°, relative to the axis of rotation R.

[0095] Preferably, the angle formed by the normal to each dispensing orifice 46 by relative to the axis of rotation R, is identical to the angle formed by the normal to each diffusion orifice 50 relative to the axis of rotation R.

[0096] Preferably, each distribution orifice 46 and each diffusion orifice 50 extends in a plane which forms an angle substantially between 20° and 60°, and preferably substantially equal to 45°, with the axis of rotation R.

[0097] Preferably, when a distribution orifice 46 is opposite a diffusion orifice 50, the two end segments 24, 36 of the respective conduits 44, 49 are in the extension of one another and preferably substantially coaxial. In other words, when the hydraulic distributor 18 and the cylinder block 10 are in an angular position where a distribution orifice 46 is opposite a diffusion orifice 50, the end segment 24 of the corresponding distribution conduit 44 and the end segment 36 of the corresponding diffusion conduit 49 are aligned.

[0098] As illustrated in Figures 1A and 1B, the presence of the receiving section 32 directly on the cylinder block 10 allows the hydraulic distributor 18, by means of its insertion section 28, to be fitted directly into the cylinder block 10, as close as possible to the cylinders 11, which has the consequence of reducing and simplifying the routing of the conduits, and of reducing the axial size of the hydrostatic machine.

[0099] In the example illustrated in [Fig.lA], which is particularly advantageous, the central chamber 22 of the hydraulic distributor 18 is connected to a cylinder 11 (at the instant when the hydraulic distributor 18 is in the appropriate angular position) directly by a rectilinear conduit (formed by a distribution conduit 44 and a diffusion conduit 49 aligned). This significantly reduces the pressure losses since no bend is present in this flow.

[0100] [Fig.5] is a partial view of [Fig.1A] theoretically illustrating the resulting forces which are exerted between the internal element 1 and the external element 2, at the level of the high pressure hydraulic circuit, for an angular position of the hydraulic distributor 18 where a distribution conduit 44 is in the closed position.

[0101] The force F shown is exerted by the hydraulic fluid on the cylinder block and tends to move the hydraulic distributor 18 and the cylinder block 10 apart. This force is compensated by an opposite force created by the axial cylinder function described above, to hold the distributor 18 against the cylinder block 10. Given its inclination relative to the axis of rotation R, this force F has a radial component Fr and an axial component Fa.

[0102] Given the symmetry of the device, the radial components Fr of all the forces F acting at the synchronization junction 37 oppose each other two by two and will therefore only constrain the cylinder block 10. The radial components Fr are therefore only acted on the material of the cylinder block 10. Thus, with a di adequate dimensioning of the cylinder block 10, this radial component Fr is not transmitted to the bearings 14, 15.

[0103] The bearings 14, 15 only undergo axially the axial component Fa of the force F which is reduced here. In the present example, the force F forming an angle of the order of 45° with the axis of rotation R (taking into account the orientation of the distribution orifice 46 and the conduits), the axial component Fa represents approximately two thirds of the total force F.

[0104] For example, for a hydraulic motor with a fluid pressure of the order of 400 bars, the force F is of the order of 35 kN, and its axial component Fa is of the order of 25 kN. Applying the component Fa to the bearings 14, 15 instead of the total force F is equivalent to a gain of the order of 30% of the force applied to the bearings. Such a gain in axial forces applied to the bearings is considerable, and makes it possible to reduce their dimensioning, or even to change technology, with the corresponding gains in size and cost.

[0105] [Fig.6] represents the hydraulic distributor 18 seen from the front, along the axis of rotation R. This figure visually illustrates the reduction of the fluid section seen along the rotation axis R. The distribution orifices 46 are seen, along the rotation axis R, as ellipses whose surface area is reduced by approximately 1 / 3 compared to the actual surface area of ​​the distribution orifices 46. This projection of the ellipse is also shown diagrammatically by the reference 56 in [Fig.3].

[0106] The bearings 14, 15 can therefore be sized down compared to the prior art. Their technology can also be reviewed, with the choice of a technology less suited to heavy loads, but which becomes suitable here given the reduction in axial load. This is the case of the standard angular contact ball bearings of the example illustrated, which are also arranged in an X-shaped assembly, which is less expensive.

[0107] The reduction of axial forces here allows the use of two angular contact ball bearings, which are designed accordingly to be identical and of a suitable internal diameter, and to have a small width.

[0108] The arrangement of the synchronization junction 37 allows for very small chain ribs. In the example illustrated [Fig.lA], the housing 5 and the first cover 6 are mounted one inside the other with a precise fit, and are coaxial with low dispersion. In a variant, illustrated in [Fig.lB], this coaxiality can be further improved by producing the housing 5 and the first cover 6 in a single piece, for example by turning. Thus, the bearing surface of the bearings 14, 15, and the distribution base 4 (and therefore the bearing surface of the circular seals 25, 27) are machined together by turning with perfect coaxiality obtained at low cost.

[0109] The chain of dimensions around the synchronization junction 37 is thus very reduced. since it only passes through the hydraulic distributor 18, the distribution base 4, the bearings 14, 15, and the cylinder block 10. These elements also provide naturally efficient adjustments in coaxiality, in particular the mounting of the bearings.

[0110] With this aim of optimizing the dimension chains, the positioning of the bearings preferably has at least one of the following characteristics: - one of the bearings (here the first bearing 14) is substantially axially aligned with the synchronization junction 37 (see axis 52 in [Fig.lA]), in other words, the insertion section of the hydraulic distributor 18 is installed under the bearing 14, and thus contributes to the compactness effect; and / or - one of the bearings (here the second bearing 15) is substantially arranged in the direction in which each end segment 24 of the distribution conduits 44 extends (see axis 53 in [Fig.1A]).

[0111] Furthermore, preferably, the hydraulic distributor 18 is connected by a ball joint to the distribution base 4. However, taking into account the arrangement according to the invention, a small amplitude ball joint is sufficient, and the circular seals 25, 27 are chosen to promote good sealing, while allowing slight swiveling. Circular seals made of a material such as polyamide are thus suitable.

[0112] Furthermore, the arrangement of the synchronization junction 37 of this example, with the shape of complementary spherical surfaces of the first and second synchronization surfaces, guarantees a swiveling of the hydraulic distributor 18 which does not generate stresses in the assembly.

[0113] Furthermore, the reduction in the axial force generated by the hydraulic fluid also applies to the cylinder function of the hydraulic distributor 18 which can therefore also be reduced by 1 / 3 in this example, further reducing the size and the dimensioning of the parts.

[0114] Furthermore, with reference to FIGS. 1A and 1B, the synchronization junction 37 has a selvedge 51 opening on the one hand into the external element 2 and on the other hand into the internal element 1, in an axial chamber 38.

[0115] The invention allows for the most accurate dimensioning of this edge 51, large enough to contain the hydraulic fluid leak, and small enough not to maintain a significant pressure gradient. The invention allows the edge 51 to be dimensioned by dimensioning the insertion 28 and receiving 32 sections. In the present example, the edge 51 has a length of 1 to 3 mm on either side of the distribution orifices 46 and the diffusion orifices 50 (in the plane of [Fig. 1A]).

[0116] This arrangement makes it possible in any case to reduce the hydraulic leakage path. The hydraulic fluid protruding at the edge 51 is quickly admitted, from a side in the space closed by the first cover 6, and on the other side in the axial chamber 38 of the internal element 1. The proximity between the masses of hydraulic fluid which pass through the cylinders 11 and which closely surround the synchronization junction 37 improves the thermal stability of the assembly by avoiding the formation of hot spots at the level of the synchronization junction 37.

[0117] The axial chamber 38 is produced by concentric machining to the cylinder block 10 and is centered on the axis of rotation R. The internal element 1 may further comprise a lubrication duct 39 allowing the hydraulic fluid to exit from the axial chamber 38, under the effect of its continuous supply by the leak at the edge 51. Advantageously, the lubrication duct 39 opens opposite a lip seal 40 which ensures the seal between the second cover 7 and the internal element 1. This arrangement allows continuous watering of the lip seal 40 by a jet of hydraulic fluid at the flow rate corresponding to the flow rate of the hydraulic fluid inlet into the axial chamber 38, and in a rotating manner thanks to the rotational movement of the outlet of the lubrication duct 39 relative to the lip seal 40, and this with a fluid having cooled in the axial chamber 38. This improves the function seal tightness and its lifespan.

[0118] Alternative embodiments may be envisaged. For example, the synchronization surfaces 31, 35 may have other shapes adapted to extend obliquely, for example shapes extending obliquely in directions opposite to the present example, conical shapes or any suitable shape.

Claims

Claims

1. Hydrostatic rotation machine comprising: - an internal element (1) and an external element (2) coaxial and mounted to rotate relative to each other around an axis of rotation (R), one of these elements being a rotor and the other of these elements being a stator, the external element (2) comprising a circumferential internal cam path (8), the internal element (1) comprising a cylinder block (10) having radial cylinders (11) provided with radially movable pistons (12) distributed circumferentially, the cylinder block (10) being arranged in the center of the cam path (8), the pistons (12) being adapted to cooperate with the cam path (8) during rotation of the rotor relative to the stator; - a hydraulic distributor (18) adapted to selectively connect the cylinders (11) to a hydraulic circuit, by means of a synchronization junction forming a rotating coupling between the rotor and the stator; this hydrostatic rotation machine being characterized in that the hydraulic distributor (18) comprises: - an insertion section (28) extending axially between a section of smaller diameter (29) and a section of larger diameter (30), this insertion section (28) having a first synchronization surface (31) extending between the contour (42) of the section of smaller diameter (29) and the contour (43) of the section of larger diameter (30); - fluid distribution conduits (44) which each comprise an end segment (24) opening transversely to the first synchronization surface (31), and obliquely relative to the axis of rotation (R); and in that the cylinder block (10) comprises: - a receiving section (32) complementary to the insertion section (28) of the hydraulic distributor (18), this receiving section (32) having a second synchronization surface (35) complementary to the first synchronization surface (31) of the hydraulic distributor (18), said synchronization junction (37) being formed from the association of the first synchronization surface (31) and the second synchronization surface (35); - fluid diffusion conduits (49) which each comprise an end segment (36) opening transversely to the second synchronization surface (35), and obliquely to the axis of rotation (R).

2. Hydrostatic rotation machine according to claim 1, characterized in that the end segments (24) of the distribution conduits (44) form an angle substantially between 20° and 60°, and preferably substantially equal to 45°, relative to the axis of rotation (R).

3. Hydrostatic rotation machine according to one of claims 1 or 2, characterized in that the end segments (36) of the diffusion conduits (49) form an angle substantially between 20° and 60°, and preferably substantially equal to 45°, relative to the axis of rotation (R).

4. Hydrostatic rotation machine according to one of the preceding claims, characterized in that: the distribution conduits (44) each open through a distribution orifice (46) onto the first synchronization surface (31), the normal to each distribution orifice (46) forming an angle substantially between 20° and 60°, and preferably substantially equal to 45°, relative to the axis of rotation R; and in that the diffusion conduits (49) each open through diffusion orifices (50) onto the second synchronization surface (35), the normal to each diffusion orifice (50) forming an angle substantially between 20° and 60°, and preferably substantially equal to 45°, relative to the axis of rotation (R).

5. Hydrostatic rotation machine according to claim 4, characterized in that the angle formed by the normal to each distribution orifice (46) relative to the axis of rotation (R), is preferably identical to the angle formed by the normal to each diffusion orifice (50) relative to the axis of rotation (R).

6. Hydrostatic rotation machine according to one of claims 4 or 5, characterized in that each distribution orifice (46) and each diffusion orifice (50) extends in a plane which forms an angle substantially between 20° and 60°, and preferably substantially equal to 45°, with the axis of rotation (R).

7. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the first synchronization surface (31) and the second synchronization surface (35) are portions of spherical surfaces.

8. Hydrostatic rotation machine according to one of claims 4 to 7, characterized in that, when the hydraulic distributor (18) and the block- cylinders (10) are in an angular position where a distribution orifice (46) is opposite a diffusion orifice (50), the end segment (24) of the corresponding distribution duct (44) and the end segment (36) of the corresponding diffusion duct (49) are aligned.

9. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the external element (2) comprises a tubular housing (5) which carries the cam path (8) and in which bearings (14, 15) are mounted ensuring the rotating mounting relative to each other of the internal element (1) and the external element (2).

10. Hydrostatic rotation machine according to claim 9, characterized in that one of said bearings (14) is substantially axially aligned with the synchronization junction (37).

11. Hydrostatic rotation machine according to claim 10, characterized in that the cylinder block (10) comprises two collars (16, 17) arranged on either side of the cylinders (11), with a bearing (14, 15) mounted between each collar (16, 17) and the external element (2).

12. Hydrostatic rotation machine according to one of claims 9 to 11, characterized in that one of said bearings (15) is substantially arranged in the direction (52) in which each end segment (24) of the distribution conduits (44) extends.

13. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the hydraulic distributor (18) comprises rectilinear distribution conduits (44) between a central chamber (22) and the first synchronization surface (31).

14. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the hydraulic distributor (18) comprises distribution conduits (44) between a peripheral chamber (23) and the first synchronization surface (31), these distribution conduits (44) comprising: a first rectilinear segment (45) parallel to the axis of rotation (R) and opening into the peripheral chamber (23); and said end segment (24) which is oblique.

15. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the diffusion ducts (49) of the cylinder block (10) are rectilinear between each cylinder (11) and the second synchronization surface (35).

16. Hydrostatic rotation machine according to one of the preceding claims, characterized in that: - the external element (2) comprises a distribution base (4) inserted in the hydraulic distributor (18), the hydraulic distributor (18) being axially movable on the distribution base (4) and the hydraulic distributor (18) being coupled in rotation with the distribution base (4); - the hydraulic distributor (18) comprises two chambers (22, 23) delimited by a circular end seal (25) and by a circular base seal (27) arranged between the distribution base (4) and the hydraulic distributor (18), the circular end seal (25) being of smaller diameter than the circular base seal (27).

17. Hydrostatic rotation machine according to claim 16, characterized in that the hydraulic distributor (18) is connected by a ball joint to the distribution base (4).

18. Hydrostatic rotation machine according to one of claims 16 or 17, when they depend on claims 9 to 12, characterized in that the external element (2) comprises in a single piece said tubular housing (5), said distribution base (4) and a first cover (6) connecting the tubular housing (5) to the distribution base (4).

19. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the synchronization junction (37) has a selvage (51) opening on the one hand into the external element (2) and on the other hand into an axial chamber (38) of the internal element (1).

20. Hydrostatic rotation machine according to claim 19, characterized in that the internal element (1) comprises a lubrication conduit (39) connecting the axial chamber (38) to a zone opposite a seal (40) to be lubricated integral with the external element (2).

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