Hydrostatic rotary machine with radial piston and optimized distribution

Abstract

Hydrostatic rotary machine comprising the following: - an internal element (1) and an external element (2) that are rotatable relative to each other about an axis of rotation (R); - a hydraulic distributor (18). The hydraulic distributor (18) comprises the following: - an insertion section (28) extending axially between a sub-section (29) with a smaller diameter and a sub-section (30) with a larger diameter, with a first synchronization surface (31) ; - Fluid distribution lines (44), each comprising an end segment (24) that opens transversely to the first synchronization surface (31) and obliquely with respect to the axis of rotation (R). The cylinder block (10) comprises the following: - a receiving section (32) which is complementary to the insertion section (28) of the hydraulic distributor (18); - Fluid diffusion lines (49) each comprising an end segment (36) that opens transversely to the second synchronization surface (35) and obliquely with respect to the axis of rotation (R).

Description

TECHNICAL AREA

[0001] The invention relates to the field of mechanics and hydraulics and relates in particular to a hydrostatic rotary machine.

[0002] Hydrostatic rotary machines are rotatable machines with a stator coupled to a rotor, which is generally connected to a rotatable drive element such as a wheel, pinion, or some transmission device.

[0003] Such a hydrostatic machine can be used as a hydraulic motor. It is therefore supplied with pressurized hydraulic fluid and, in response, drives the rotatable drive element.

[0004] The hydrostatic machine can also be used as a hydraulic pump. It receives torque transmitted through the rotating drive element and, in response, compresses the hydraulic fluid. STATE OF THE ART

[0005] Patent application WO2020008145 describes a hydrostatic rotary machine comprising the following: - an internal element and an external element, which are coaxial and rotatably mounted relative to each other about an axis of rotation, wherein one of these elements is a rotor and the other of these elements is a stator, wherein the external element comprises an internal circumferential cam track, and the internal element comprises a cylinder block having radial cylinders equipped with radially movable pistons and distributed around the circumference, the cylinder block being located at the center of the cam track, the pistons being designed to interact with the cam track during rotation of the rotor relative to the stator; - a hydraulic distributor designed to selectively connect the cylinders to a hydraulic circuit through a synchronization link forming a rotatable coupling between the rotor and the stator.

[0006] Although this hydrostatic machine has advantages on several levels, it can still be improved in terms of optimizing its dimensions and compactness. DETAILING OF THE INVENTION

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

[0008] The invention aims to provide a hydrostatic rotary machine comprising the following: - an internal element and an external element, which are coaxial and rotatably mounted relative to each other about an axis of rotation, wherein one of these elements is a rotor and the other of these elements is a stator, wherein the external element comprises an internal circumferential cam track, and the internal element comprises a cylinder block having radial cylinders provided with radially movable pistons and distributed around the circumference, the cylinder block being located at the center of the cam track, the pistons being designed to interact with the cam track during rotation of the rotor relative to the stator; - a hydraulic distributor designed to selectively connect the cylinders to a hydraulic circuit through a synchronization link forming a rotatable coupling between the rotor and the stator.

[0009] Furthermore, the hydraulic distributor includes the following: - an insertion section extending axially between a sub-area with a smaller diameter and a sub-area with a larger diameter, wherein this insertion section has a first synchronization surface extending between the contour of the sub-area with the smaller diameter and the contour of the sub-area with the larger diameter; - Fluid distribution lines, each comprising an end segment that opens transversely to the first synchronization surface and obliquely with respect to the axis of rotation.

[0010] The cylinder block also includes the following: - a receiving section complementary to the insertion section of the hydraulic distributor, wherein this receiving section has a second synchronization surface complementary to the first synchronization surface of the hydraulic distributor, wherein the synchronization connection is formed from the union of the first synchronization surface and the second synchronization surface; - Fluid diffusion lines, each comprising an end segment that opens transversely to the second synchronization surface and obliquely with respect to the axis of rotation.

[0011] According to the invention, the hydrostatic machine simultaneously exhibits an increase in compactness and an optimization of its dimensions.

[0012] The coupling of the hydraulic distributor's insertion section and the cylinder block's receiving section at the synchronization point ensures the fluid distribution function for the hydrostatic machine, which consists of cyclically aligning each cylinder with either the high-pressure or low-pressure side of the fluid circuit. This distribution function is achieved here by forces generated by the hydraulic fluid and exerted at the synchronization point. These forces are obliquely oriented due to the properties of the synchronization surfaces and the corresponding lines, thus exhibiting both an axial and a radial component.Given the arrangement of the hydrostatic rotary engine with its radial pistons, the radial components of these forces are exerted only at the level of the cylinder block and compensate for each other there without being transmitted to other elements. Thus, a portion of the force generated by the hydraulic fluid pressure, required for energy transmission, is not applied to the bearings that couple the rotor and stator, but is instead applied to a single element, which can be manufactured from a single piece and whose dimensions can easily be designed to withstand these stresses within its material.

[0013] For a hydraulic motor operating at a pressure on the order of 400 bar, for example, the force generated at the level of a distribution line at the moment it is cyclically closed by the second synchronization surface is on the order of 35 kN. In the case of a distribution line generating a force at 45° with respect to the axis of rotation, the axial component of this force represents approximately 2 / 3 of the total force. This is the force that is applied axially to other elements, and in particular to the bearings intended to support the stresses, depending on the mounting of the bearings provided for the rotary connection of the rotor and stator about the axis of rotation. In this illustrative example, a reduction of on the order of 10 kN in the force applied to these bearings is obtained.In the majority of bearing assemblies, a single bearing supports the majority of this axial force, and such a reduction of 10 kN is very significant.

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

[0015] The overall and especially the axial space requirement of the hydraulic distributor is also reduced because the axial reduction of the forces associated with the fluid pressure also makes it possible to reduce the force that the hydraulic distributor must exert on the cylinder block, with the aim of maintaining the integrity of the synchronization connection (the "actuator" function of the hydraulic distributor). The hydraulic distributor can therefore also be dimensioned in a more compact and simplified manner.

[0016] The second consequence of the invention concerns the simplification of the dimensional chains through the arrangement of the synchronization connection, which also enables an increase in compactness and reliability.

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

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

[0019] Thus, the invention makes it possible either to optimize the dimensions of several components and consequently gain in compactness and cost for the hydrostatic machine as a whole, or to oversize the machine while maintaining constant compactness and cost, thereby making it suitable for other applications, such as heavier-duty applications, higher-speed applications, or those requiring a longer service life. Furthermore, the simplified design, made possible by the arrangement of the synchronization link, allows for increases in reliability and maintainability.

[0020] The invention also enables simpler manufacturing processes, which also allow for a reduction in manufacturing costs.

[0021] The hydrostatic rotary machine according to the invention can include the following additional features alone or in combination: - the end segments of the distribution lines form an angle essentially between 20° and 60° and preferably essentially equal to 45° with respect to the axis of rotation; - the end segments of the diffusion lines form an angle essentially between 20° and 60° and preferably essentially equal to 45° with respect to the axis of rotation; - the distribution lines each open through a distribution opening on the first synchronization surface, wherein the normal to each distribution opening forms an angle substantially between 20° and 60° and preferably substantially equal to 45° with respect to the axis of rotation R; and the diffusion lines each open through diffusion openings on the second synchronization surface, wherein the normal to each diffusion opening forms an angle substantially between 20° and 60° and preferably substantially equal to 45° with respect to the axis of rotation; - the angle formed by the normal to each distribution opening with respect to the axis of rotation is preferably identical to the angle formed by the normal to each diffusion opening with respect to the axis of rotation; - each distribution opening and each diffusion opening extends in a plane that forms an angle substantially between 20° and 60° and preferably substantially equal to 45° with the axis of rotation; - the first synchronization surface and the second synchronization surface are parts of spherical surfaces; - when the hydraulic distributor and the cylinder block are in an angular position in which a distribution opening is opposite a diffusion opening, the end segment of the corresponding distribution line and the end segment of the corresponding diffusion line are aligned; - the external element comprises a tubular housing that carries the cam track and in which bearings are mounted that ensure the rotatable mounting of the internal element and the external element in relation to each other; - one of the bearings is essentially axially aligned with the synchronization link; - the cylinder block comprises two flanges arranged on both sides of the cylinders, with a bearing mounted between each flange and the external element; - one of the bearings is essentially arranged in the direction in which each end segment of the distribution lines extends; - the hydraulic distributor includes straight distribution lines between a central chamber and the first synchronization surface; - the hydraulic distributor comprises distribution lines between a circumferential chamber and the first synchronization surface, these distribution lines comprising: a first straight segment parallel to the axis of rotation, which opens into the circumferential chamber; and the end segment, which is inclined; - the diffusion lines of the cylinder block are straight between each cylinder and the second synchronization surface; - the external element comprises a distribution base which is inserted into the hydraulic distributor, wherein the hydraulic distributor is axially movable on the distribution base and the hydraulic distributor is rotationally coupled to the distribution base; - the hydraulic distributor comprises two chambers bounded by a circular end seal and a circular base seal, arranged between the distribution base and the hydraulic distributor, the circular end seal having a smaller diameter than the circular base seal; - the hydraulic distributor is connected to the distribution base by a ball joint connection; - the external element comprises the tubular housing, the distribution base and a first cover connecting the tubular housing to the distribution base in a single piece; - the synchronization connection has an edge that opens into the external element on one side and into an axial chamber of the internal element on the other; - the internal element includes a lubrication line that connects the axial chamber to a zone opposite a seal to be lubricated, which is rigidly connected to the external element. DEPTH OF THE FIGURES

[0022] Other features and advantages of the invention will become apparent from the following non-limiting description with reference to the accompanying drawings; they show: - Fig. 1A an axial sectional view of a hydrostatic rotary machine according to the invention; - Fig. 1B a view similar to Fig. 1A for a different angular position of the rotor in relation to the stator; - Fig. 2 a detailed view of an axial section of the hydrostatic machine showing the hydraulic distributor in a different angular position; - Fig. 3 a perspective view of the hydraulic distributor of the hydrostatic machine; - Fig. 4 a perspective view of the cylinder block of the hydrostatic machine; - Fig. 5 a schematic detail view of Fig. 1A; and - Fig. 6 A front view of the hydraulic distributor of the hydrostatic machine.

[0023] In the figures, similar elements common to the different embodiments bear the same reference symbols. DETAILED DESCRIPTION

[0024] Fig. Figure 1A shows a hydrostatic rotary machine according to the invention in section along a plane extending along its axis of rotation R. Fig. Figure 1B shows the hydrostatic machine according to the same section for a different angular position of the rotor in relation to the stator.

[0025] This hydrostatic machine is either a hydraulic motor that rotates an element using a pressurized hydraulic fluid, or a hydraulic pump designed to pressurize a hydraulic fluid using the rotation of an element.

[0026] The hydrostatic rotary machine comprises an internal element 1 and an external element 2, which are mounted in relation to each other rotatably about the axis of rotation R by bearings 14, 15.

[0027] In the present illustrative example, the hydrostatic machine is a hydraulic motor and the internal element 1 is rigidly connected to a drive element, which here is formed from a splined shaft 3.

[0028] Between the internal element 1 and the external element 2, one of these elements is a rotor, while the other is a stator. In the present example, the external element 2 is a stator and is connected to a frame such as a fixed structure or one mounted on a vehicle, while the internal element 1 is a rotor and the splined shaft 3 is connected, for example, to a wheel or a pinion.

[0029] The external element 2 comprises a housing 5, which here has a tubular shape, with a first cover 6, which covers one of the openings (on the right side of the Fig. 1A) this tubular housing 5 hermetically seals, and a second lid 7, which has the opposite opening (on the left side of the Fig. 1A) hermetically sealed.

[0030] The external element 2 is also rigidly connected to a cam track 8, which is characteristic of hydrostatic radial piston machines. In a known manner, this cam track 8 is a circumferential feature within the wall of the housing 5 with a profile formed by cavities and protrusions that create a cyclic profile with a sequence of increasing and decreasing radii, synchronized with the inlet and outlet movement of the radial pistons.

[0031] This cam track 8 can, for example, be machined directly on an internal surface of the external element 2, or directly on an internal surface of the element 5. However, as shown in the figures, the present example preferably uses a cam track 8 that is supported by a cam ring 9 such as that described in patent application WO2020008145. This cam ring 9 is inserted into the housing 5 of the external element 2 on an internal surface and is rotationally fixed by any means.

[0032] The internal element 1 in turn comprises a cylinder block 10, which is also specific to hydrostatic radial piston machines. This cylinder block 10 is equipped with cylinders 11 in which radially movable pistons 12 are mounted.

[0033] In a known manner, the cylinders 11 are radial cylinders extending over the entire circumference of the cylinder block 10, which are distributed at angles in a regular manner around the axis of rotation R, and the pistons 12 each include at their end, which is facing the cam track 8, a roller 13 which enables rolling without sliding on the cam track 8.

[0034] The cam tracks for a hydrostatic machine, the interaction with the radial pistons and the methods for synchronization by selectively linking the cylinders with the hydraulic fluid circuit are also known and are not described in more detail here.

[0035] The internal element 1 and the external element 2 are rotatably mounted relative to each other by means of, in this example, a first bearing 14 and a second bearing 15, which are mounted directly between the internal element 1 and the external element 2. In addition to the cam ring 9, the tubular housing 5 supports these bearings 14 and 15. The drawings illustrate two possible mountings of the bearings 14 and 15 in the housing 5: a direct mounting of the bearing with its external ring in contact with the housing 5 (this is the case of the first bearing 14); and a mounting of the bearing in the housing with an intermediate support ring (this is the case of the second bearing 15), and in this example, this support ring is part of the second cover 7.

[0036] The cylinder block 10 comprises two flanges 16, 17 arranged on both sides of the cylinders 11, wherein a bearing 14, 15 is mounted between each flange 16, 17 and the external element 2, wherein the internal ring of each bearing 14, 15 is mounted directly on the corresponding flange 16, 17.

[0037] A simple assembly of the bearing, which generates reduced dimensional chains, is thus obtained, with the cam ring 9 being mounted in the housing 5 and the bearings 14, 15, which are arranged on both sides of this cam ring 9, forming the direct interface between the internal element 1 and the external element 2.

[0038] The hydrostatic machine also includes means for distributing and synchronizing the hydraulic fluid. These means include a hydraulic distributor 18 and a distribution base 4.

[0039] The distribution base 4 includes a fluid inlet 19 and a fluid outlet 20 (partially shown in the sectional view of Fig. 1A visible and in Fig. 1B visible), which are connected in the classic manner to the high-pressure and low-pressure parts of a hydraulic circuit. The hydrostatic machine also includes a drain.

[0040] The distribution base 4 is permanently connected to the external element 2. In this example, the distribution base 4 is permanently connected to the first cover 6.

[0041] The hydraulic distributor 18 is mounted on the distribution base 4, while being axially movable relative to the latter, with the two parts being rotationally coupled. Receptacles 26 are formed opposite each other in the distribution base 4 and in the hydraulic distributor 18 and enable rotational coupling by means of pins, while allowing axial sliding, and can also accommodate springs for exerting pressure from the hydraulic distributor 18 against the internal element 1.

[0042] The hydraulic distributor 18 comprises a central chamber 22 and a circumferential chamber 23, each of which is connected to the fluid inlet 19 or fluid outlet 20. Fig. 1B represents the connection of chambers 22, 23 with fluid inlets / outlets 19, 20 according to the present example.

[0043] Seals enable the hermetic closure of chambers 22 and 23, while allowing axial movement of the hydraulic distributor 18 on the distribution base 4. These seals comprise a circular end seal 25 and a circular base seal 27.

[0044] Fig. 2 is a partial view of Fig. 1A according to a different angular position, which shows the connection of the circumferential chamber 23 with the hydraulic distributor 18.

[0045] In a known manner, the two seals 25 and 27 have different diameters, with the aim of generating an axial actuating function for the hydraulic distributor 18. This axial actuating function enables the hydraulic distributor 18 to be held against the internal element 1 by counteracting the forces generated during synchronization, i.e., the selective pressurization of the cylinders 11. The distributor base 4 thus includes an axial opening 21, which carries the circular end seal 25, while the circular base seal 27 is arranged at the base of the distributor base 4. The diameter of the circular end seal 25 is smaller than that of the circular base seal 27 according to a ratio that determines the force required for the axial actuating function.

[0046] The actuator thus generated by the hydraulic distributor 18 has the effect of counteracting the repulsive force exerted in the interface (the synchronization connection 37) between the hydraulic distributor 18 and the cylinder block 10.

[0047] The hydraulic distributor 18 also includes an insertion section 28 that extends axially between a smaller-diameter sub-section 29 and a larger-diameter sub-section 30. In other words, the insertion section 28 is a material sub-section that extends between a plane designated by the reference numeral 29 in Fig. 1A bears, and a plane that bears the reference numeral 30 in Fig. 1A carries, extends.

[0048] Fig. Figure 3 is a perspective view of the hydraulic distributor 18 alone. Since the hydraulic distributor 18 is a recirculating element, the two sub-sections 29 and 30 each define a circular shape whose contour is a circle. The sub-section 29 with the smaller diameter thus has a contour 42, which is a circle, and the sub-section 30 with the larger diameter has a contour 43, which is a circle. The diameter of contour 42 is therefore smaller than the diameter of contour 43.

[0049] The insertion section 28 of the hydraulic distributor 18 has a first synchronization surface 31 that extends obliquely between the contour 42 of the smaller diameter sub-section 29 and the contour 43 of the larger diameter sub-section 30. The first synchronization surface extends obliquely in that it is neither parallel nor perpendicular to the axis of rotation R.

[0050] In the present example, the first synchronization surface 31 is a spherical zone defined as part of the surface of a sphere passing through the two contours 42, 43 and intersected by the two sub-areas 29, 30.

[0051] In the first illustrative example, the radius of this sphere is on the order of 4 cm.

[0052] The central chamber 22 and the circumferential chamber 23 are each connected to a first synchronization surface 31 by fluid distribution lines 44, each comprising an end segment 24 that opens transversely to the first synchronization surface 31 and obliquely with respect to the axis of rotation R. In the present example, these end segments 24 form an angle α between 20° and 60° with the axis of rotation R, and preferably 45°, as shown. In other words, the longitudinal axis 54 of each end segment 24 intersects the axis of rotation R and forms the angle α with it (it is the interior angle that is considered here).

[0053] In the present example, more precisely, each end segment 24 leads into the second synchronization surface 35 by being essentially orthogonal to a plane tangential to this surface.

[0054] In the present example, the distribution lines 44, which connect the central chamber 22 with the first synchronization surface 31, are straight. The end segment 24 of each therefore lies in the extension of the remainder of the distribution line 44, and the entire distribution line 44 forms an angle, which in this example is 45°, with the axis of rotation R.

[0055] 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 greatly shortened, which also contributes to reducing pressure losses.

[0056] In the present example, the distribution lines 44, which connect the circumferential chamber 23 with the first synchronization surface 31, each comprise the following: a first straight segment 45 parallel to the axis of rotation R, wherein this first segment opens into the circumferential chamber 23; and the end segment 24, which is inclined, with its angle of 45° in this example with respect to the axis of rotation R.

[0057] Furthermore, the distribution lines 44 each terminate through a distribution opening 46 at the first synchronization surface 31 (see Fig. 3) These distribution openings 46 are oriented on the first synchronization surface 31 such that the normal to each distribution opening 46, which intersects the axis of rotation R, forms an angle substantially between 20° and 60° and preferably 45° with respect to the axis of rotation R.

[0058] The first synchronization surface 31 is intended to interact with the internal element 1 within the framework of the synchronization function, which aims to selectively distribute the hydraulic fluid by utilizing the rotation of the rotor relative to the stator. The cylinder block 10 interacts directly with the first synchronization surface 31 without requiring an interface through other components of the internal element 1.

[0059] The cylinder block 10 in turn 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 sub-section 33 with a smaller diameter and a sub-section 34 with a larger diameter.

[0060] Fig. Figure 4 is a perspective view of the cylinder block 10 alone. The smaller diameter section 33 has a cavity with a contour 47, which is a circle, and the larger diameter section 34 has a cavity with a contour 48, which is also a circle. The diameter of contour 47 is therefore smaller than the diameter of contour 48.

[0061] The receiving section 32 of the cylinder block 10 has a second 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 in that it is neither parallel nor perpendicular to the axis of rotation R.

[0062] The second synchronization surface 35 is complementary to the first synchronization surface 31 and consequently, in this example, it has the form of a spherical zone, that is, a part of the surface of a sphere, which passes through the two contours 47, 48 and is intersected by the two sub-areas 33, 34.

[0063] With regard to the Fig. 1A and Fig. 1B, when the hydrostatic machine is in the operating state, the first synchronization surface 31 is acted upon in the direction of the second synchronization surface 35, the connection of these two synchronization surfaces 31, 35 forming a synchronization connection 37 in which the hydraulic fluid is selectively distributed between two elements with a relative rotation.

[0064] The cylinder block 10 also includes diffusion lines 49 for the hydraulic fluid. These diffusion lines 49 connect the second synchronization surface 35 to the cylinders 11 for fluid exchange with respect to the movement of the pistons 12. Each of these diffusion lines 49 includes an end segment 36 that opens transversely to the second synchronization surface 35 and obliquely with respect to the axis of rotation R. In the present example, these end segments 36 form an angle α between 20° and 60° with the axis of rotation R, and preferably 45°, as shown. 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 interior angle that is considered here).

[0065] In the present example, more precisely, each end segment 36 leads into the second synchronization surface 35 by being essentially orthogonal to a plane tangential to this surface.

[0066] In the present example, the diffusion conduits 49 are straight. The end segment 36 of each therefore lies in the extension of the remainder of the diffusion conduit 49, and the entire diffusion conduit 49 forms an angle, which in this example is 45°, with the axis of rotation R.

[0067] Furthermore, the diffusion lines 49 each open through a diffusion opening 50 at the second synchronization surface 35 (see Fig. 4) These diffusion openings 50 are oriented on the second synchronization surface 35 such that the normal to each diffusion opening 50, which intersects the axis of rotation R, forms an angle substantially between 20° and 60° and preferably 45° with respect to the axis of rotation R.

[0068] Preferably, the angle formed by the normal to each distribution opening 46 with respect to the axis of rotation R is identical to the angle formed by the normal to each diffusion opening 50 with respect to the axis of rotation R.

[0069] Preferably each distribution opening 46 and each diffusion opening 50 extend in a plane forming an angle substantially between 20° and 60° and preferably substantially 45° with the axis of rotation R.

[0070] When a distribution opening 46 is located opposite a diffusion opening 50, the two end segments 24, 36 of the respective lines 44, 49 are preferably aligned with each other and are preferably substantially coaxial. In other words, when the hydraulic distributor 18 and the cylinder block 10 are in an angular position in which a distribution opening 46 is located opposite a diffusion opening 50, the end segment 24 of the corresponding distribution line 44 and the end segment 36 of the corresponding diffusion line 49 are aligned.

[0071] As in Fig. 1A and Fig. As shown in Figure 1B, the presence of the receiving section 32 directly on the cylinder block 10 allows the hydraulic distributor 18 to be embedded directly into the cylinder block 10 through its insertion section 28, in close proximity to the cylinders 11, which has the consequence that the routing of the lines is reduced and simplified and the axial space requirement of the hydrostatic machine is reduced.

[0072] In the Fig. In the example shown in Figure 1A, it is particularly advantageous to connect the central chamber 22 of the hydraulic distributor 18 directly to a cylinder 11 (at the moment when the hydraulic distributor 18 is in the adjusted angular position) via a straight line (formed by an aligned distribution line 44 and diffusion line 49). This significantly reduces pressure losses, as there is no bending in this flow.

[0073] Fig. 5 is a partial view of Fig. 1A, which theoretically represents the resultant forces 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 in which a distribution line 44 is in the closed position.

[0074] The force F shown is exerted on the cylinder block by the hydraulic fluid and tends to remove the hydraulic distributor 18 and the cylinder block 10. This force is compensated by an opposing force generated by the previously described axial actuator function, which holds the distributor 18 against the cylinder block 10. Considering its inclination with respect to the axis of rotation R, this force F has a radial component Fr and an axial component Fa.

[0075] Given the symmetry of the device, the radial components Fr oppose all forces F exerted at the level of the synchronization connection 37 in pairs and consequently only restrict the cylinder block 10. The radial components Fr are therefore only exerted on the material of the cylinder block 10. With suitable dimensioning of the cylinder block 10, this radial component Fr is therefore not transmitted to the bearings 14, 15.

[0076] The bearings 14, 15 experience only the axial component Fa of the force F, which is reduced here. Since, in the present example, the force F forms an angle on the order of 45° with the axis of rotation R (considering the orientation of the distribution opening 46 and the pipes), the axial component Fa represents approximately two-thirds of the total force F.

[0077] For a hydraulic motor with a fluid pressure on the order of 400 bar, the force F is, for example, on the order of 35 kN, and its axial component Fa is on the order of 25 kN. Applying the component Fa instead of the total force F to the bearings 14, 15 corresponds to an increase on the order of 30% of the force applied to the bearings. Such an increase in the axial forces applied to the bearings is considerable and makes it possible to reduce their dimensions, even to change the technology, with corresponding gains in space requirements and costs.

[0078] Fig. Figure 6 shows the hydraulic distributor 18 viewed from the front along the axis of rotation R. This figure visually illustrates the reduction of the fluid cross-section as seen along the axis of rotation R. The distribution openings 46 appear as ellipses when viewed along the axis of rotation R, with a surface area reduced by approximately 1 / 3 compared to the actual surface area of ​​the distribution openings 46. This elliptical projection is also indicated by the reference numeral 56 in Figure 6. Fig. 3. Schematized.

[0079] Bearings 14 and 15 can therefore be dimensioned downwards in relation to the state of the art. Their technology can also be reconsidered, with the selection of a technology less suited to high loads, which, however, is adapted here in view of the reduction of the axial load. This is the case with the standard angular contact ball bearings of the example shown, which are also arranged according to an X-mounting, which is less expensive.

[0080] The reduction of axial stresses allows the use of two slant-contact ball bearings, which are accordingly designed to be identical, have a matched inner diameter, and a small width.

[0081] The arrangement of the synchronization link 37 enables very reduced dimension chains. In the Fig. In the example shown in 1A, the housing 5 and the first cover 6 are mounted together with a precise alignment and are coaxial with low variation. As a variant, which is shown in Fig. As shown in Figure 1B, this coaxiality can be further improved by machining the housing 5 and the first cover 6 from a single piece, for example by turning. Thus, the area of ​​the bearings 14, 15 and the distribution base 4 (and consequently the area of ​​the circular seals 25, 27) are machined together by turning with perfect coaxiality, which is achieved at low cost.

[0082] The dimensional chain around the synchronization connection 37 is thus greatly reduced, as it only passes through the hydraulic distributor 18, the distribution base 4, the bearings 14, 15 and the cylinder block 10. These elements also naturally provide high-performance adjustments in coaxiality, especially in the mounting of the bearings.

[0083] In this optical optimization of the dimensional chains, the positioning of the bearings preferably has at least one of the following properties: - one of the bearings (here the first bearing 14) is essentially axially aligned with the synchronization link 37 (see axis 52 in Fig. 1A) aligned, in other words, the insertion section of the hydraulic distributor 18 is installed below the bearing 14 and thus benefits from the compactness effect; and / or - one of the bearings (here the second bearing 15) is essentially arranged in the direction in which each end segment 24 of the distribution lines 44 extends (see axis 53 in Fig. 1A).

[0084] Furthermore, the hydraulic distributor 18 is preferably connected to the distribution base 4 by a ball joint connection. However, in view of the arrangement according to the invention, a ball joint connection with a small amplitude is sufficient, and the circular seals 25, 27 are selected to promote good sealing while allowing easy rotation. Circular seals made of a material such as polyamide are therefore suitable.

[0085] Furthermore, the arrangement of the synchronization connection 37 of this example, with the shape of spherical complementary surfaces of the first and second synchronization surfaces, guarantees a rotation of the hydraulic distributor 18 that does not create any restrictions in the assembly.

[0086] Furthermore, the reduction of the axial force generated by the hydraulic fluid also applies to the actuator function of the hydraulic distributor 18, which can therefore also be reduced by 1 / 3 in this example, which also reduces the space requirement and the dimensioning of the parts.

[0087] With reference to Fig. 1A and Fig. 1B also has the synchronization connection 37 an edge 51 which opens on the one hand into the external element 2 and on the other hand into the internal element 1 in an axial chamber 38.

[0088] The invention enables extremely precise dimensioning of this edge 51, which is large enough to contain the leakage of hydraulic fluid and small enough to avoid a large pressure gradient. The invention allows the edge 51 to be dimensioned by dimensioning the insertion section 28 and the receiving section 32. In the present example, the edge 51 has a length of 1 to 3 mm on both sides of the distribution openings 46 and the diffusion openings 50 (in the plane of the Fig. 1A).

[0089] This arrangement, in any case, makes it possible to reduce the hydraulic leakage path. The hydraulic fluid emerging at the level of edge 51 is quickly drawn in, on the one hand into the space closed by the first cover 6, and on the other hand into the axial chamber 38 of the internal element 1. The proximity between the hydraulic fluid masses passing through the cylinders 11 and the synchronization connection 37 improves the thermal stability of the entire assembly by preventing the formation of hot spots at the level of the synchronization connection 37.

[0090] The axial chamber 38 is formed by concentric machining on the cylinder block 10 and is centered on the axis of rotation R. The internal element 1 can also include a lubrication line 39, which allows the hydraulic fluid to exit the axial chamber 38 under the influence of its continuous supply through the leak at the edge 51. Advantageously, the lubrication line 39 terminates opposite a lip seal 40, which ensures a tight seal between the second cover 7 and the internal element 1. This arrangement allows the lip seal 40 to be continuously sprayed with a jet of hydraulic fluid in the quantity corresponding to the quantity of hydraulic fluid entering the axial chamber 38, and in a rotating manner due to the rotational movement of the outlet of the lubrication line 39 relative to the lip seal 40, using fluid that has cooled in the axial chamber 38.This improves the sealing function of the seal and its service life.

[0091] Alternative designs may be considered. For example, the synchronization surfaces 31, 35 may have other shapes designed to extend obliquely, such as shapes extending obliquely in directions opposite to the present example, conical shapes, or any suitable shape. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2020008145 [0005, 0031]

Claims

[1] Hydrostatic rotary machine comprising: - an internal element (1) and an external element (2) which are coaxial and mounted to rotate relative to one another about 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 an internal circumferential cam track (8), the internal element (1) comprising a cylinder block (10) having radial cylinders (11) provided with radially movable pistons (12) distributed over the circumference, the cylinder block (10) being arranged in the center of the cam track (8), the pistons (12) being designed to cooperate with the cam track (8) during the rotation of the rotor relative to the stator; - a hydraulic distributor (18) adapted to selectively connect the cylinders (11) to a hydraulic circuit through a synchronization connection forming a rotatable coupling between the rotor and the stator; said hydrostatic rotary machine characterized by is that the hydraulic distributor (18) comprises: - an insertion section (28) extending axially between a partial region (29) of smaller diameter and a partial region (30) of larger diameter, said insertion section (28) having a first synchronization surface (31) extending between the contour (42) of the partial region (29) of smaller diameter and the contour (43) of the partial region (30) of larger diameter; - fluid distribution lines (44), each comprising an end segment (24) opening transversely to the first synchronization surface (31) and obliquely with respect to the rotation axis (R); and that the cylinder block (10) comprises: - a receiving portion (32) complementary to the insertion portion (28) of the hydraulic distributor (18), said receiving portion (32) having a second synchronization surface (35) complementary to the first synchronization surface (31) of the hydraulic distributor (18), said synchronization connection (37) being formed by linking the first synchronization surface (31) and the second synchronization surface (35); - fluid diffusion lines (49) each comprising an end segment (36) which opens transversely to the second synchronization surface (35) and obliquely with respect to the rotation axis (R). [2] Hydrostatic rotary machine according to claim 1, characterized by that the end segments (24) of the distribution lines (44) form an angle substantially between 20° and 60° and preferably substantially equal to 45° with respect to the axis of rotation (R). [3] Hydrostatic rotary machine according to one of claims 1 or 2, characterized by that the end segments (36) of the diffusion lines (49) form an angle substantially between 20° and 60° and preferably substantially equal to 45° with respect to the axis of rotation (R). [4] Hydrostatic rotary machine according to one of the preceding claims, characterized byin that: the distribution lines (44) each open through a distribution opening (46) on the first synchronization surface (31), the normal to each distribution opening (46) forming an angle substantially between 20° and 60° and preferably substantially equal to 45° with respect to the rotation axis R; and in that the diffusion lines (49) each open through diffusion openings (50) on the second synchronization surface (35), the normal to each diffusion opening (50) forming an angle substantially between 20° and 60° and preferably substantially equal to 45° with respect to the rotation axis (R). [5] Hydrostatic rotary machine according to claim 4, characterized by that the angle formed by the normal to each distribution opening (46) with respect to the rotation axis (R) is preferably identical to the angle formed by the normal to each diffusion opening (50) with respect to the rotation axis (R). [6] Hydrostatic rotary machine according to one of claims 4 or 5, characterized by that each distribution opening (46) and each diffusion opening (50) extend in a plane forming an angle substantially between 20° and 60° and preferably substantially equal to 45° with the axis of rotation (R). [7] Hydrostatic rotary machine according to one of the preceding claims, characterized by that the first synchronization surface (31) and the second synchronization surface (35) are parts of spherical surfaces. [8] Hydrostatic rotary machine according to one of claims 4 to 7, characterized by that, when the hydraulic distributor (18) and the cylinder block (10) are in an angular position in which a distribution opening (46) is opposite a diffusion opening (50), the end segment (24) of the corresponding distribution line (44) and the end segment (36) of the corresponding diffusion line (49) are aligned. [9] Hydrostatic rotary machine according to one of the preceding claims, characterized by in that the external element (2) comprises a tubular housing (5) which carries the cam track (8) and in which bearings (14, 15) are mounted which ensure the rotatable mounting of the internal element (1) and the external element (2) with respect to one another. [10] Hydrostatic rotary machine according to claim 9, characterized by that one of the bearings (14) is substantially axially aligned with the synchronization connection (37). [11] Hydrostatic rotary machine according to claim 10, characterized by in that the cylinder block (10) comprises two flanges (16, 17) arranged on both sides of the cylinders (11), a bearing (14, 15) being mounted between each flange (16, 17) and the external element (2). [12] Hydrostatic rotary machine according to one of claims 9 to 11, characterized bythat one of the bearings (15) is arranged substantially in the direction (52) in which each end segment (24) of the distribution lines (44) extends. [13] Hydrostatic rotary machine according to one of the preceding claims, characterized by that the hydraulic distributor (18) comprises straight distribution lines (44) between a central chamber (22) and the first synchronization surface (31). [14] Hydrostatic rotary machine according to one of the preceding claims, characterized by in that the hydraulic distributor (18) comprises distribution lines (44) between a peripheral chamber (23) and the first synchronization surface (31), these distribution lines (44) comprising: a first rectilinear segment (45) parallel to the axis of rotation (R), which opens into the peripheral chamber (23); and the end segment (24) which is oblique. [15] Hydrostatic rotary machine according to one of the preceding claims, characterized bythat the diffusion lines (49) of the cylinder block (10) between each cylinder (11) and the second synchronization surface (35) are straight. [16] Hydrostatic rotary machine according to one of the preceding claims, characterized by , that: - the external element (2) comprises a distribution base (4) which is inserted into the hydraulic distributor (18), wherein the hydraulic distributor (18) is axially movable on the distribution base (4) and the hydraulic distributor (18) is rotationally coupled to 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) having a smaller diameter than the circular base seal (27). [17] Hydrostatic rotary machine according to claim 16, characterized by that the hydraulic distributor (18) is connected to the distribution base (4) by a ball joint connection. [18] Hydrostatic rotary machine according to one of claims 16 or 17 when dependent on claims 9 to 12, characterized by in that the external element (2) comprises in a single piece the tubular housing (5), the distribution base (4) and a first cover (6) connecting the tubular housing (5) to the distribution base (4). [19] Hydrostatic rotary machine according to one of the preceding claims, characterized by that the synchronization connection (37) has an edge (51) which opens 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 rotary machine according to claim 19, characterized byin that the internal element (1) comprises a lubrication line (39) connecting the axial chamber (38) to a zone opposite a seal (40) to be lubricated, which is integral with the external element (2).

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