Hydraulic machine including a dog brake

Abstract

The hydraulic machine (2) comprises: - a bearing support (8), - a cylinder block (16), - a brake piston (20) mounted to move relative to the bearing support between a braking position in which the piston is engaged with the cylinder block by form complementarity so as to block a rotation of the cylinder block relative to the piston and a braking position in which the piston leaves the cylinder block free to rotate relative to the piston, and - at least one bearing (14) bearing against the bearing support (8), the piston and the bearing being located on the same side of the cylinder block by reference to a direction of a main axis (XX) of the machine, a periphery (59) of the piston (20) oriented in the opposite direction to the axis being shaped to prevent a rotation of the piston relative to the bearing support. Abstract figure: Fig. 2

Description

Title of the invention: Hydraulic machine comprising a dog brake FIELD OF THE INVENTION

[0001] The invention relates to hydraulic machines. STATE OF THE ART

[0002] Document FR-2 765 637 discloses a rotating hydraulic machine comprising a shaft, a cam and a cylinder block secured to the rotating shaft and carrying pistons capable of following the cam. The shaft is carried by bearings resting on a bearing support. The machine comprises a dog-type brake, which comprises a piston mounted to move relative to the bearing support between a braking position in which the piston blocks rotation of the cylinder block and a braking position in which the piston leaves the cylinder block free to rotate. The bearings and the brake piston are located on different sides of the cylinder block with reference to a direction of an axis of rotation of the machine.

[0003] However, it is desired, particularly for reasons of compactness, to have a machine in which the brake piston and the bearings are on the contrary located on the same side of the cylinder block. But this configuration raises problems of space requirement for housing the brake piston.

[0004] An aim of the invention is to obtain a hydraulic machine meeting this desire. Statement of the invention

[0005] For this purpose, according to the invention, a hydraulic machine is provided comprising:

[0006] - a bearing support,

[0007] - a cylinder block,

[0008] - a brake piston mounted movably relative to the bearing support between a position braking in which the piston is engaged with the cylinder block by form complementarity so as to block a rotation of the cylinder block relative to the piston and a braking position in which the piston leaves the cylinder block free to rotate relative to the piston, and

[0009] - at least one bearing bearing against the bearing support, the piston and the bearing located on the same side of the cylinder block with reference to a direction of a main axis of the machine,

[0010] a circumference of the piston oriented in a radial direction opposite to the axis being shaped to block rotation of the piston relative to the bearing support.

[0011] In the present application, the expression "direction opposite the axis" means radially external, and "in the direction of the axis" means radially internal.

[0012] Thus, this architecture makes it possible to properly accommodate the brake piston without loss of volume while the piston and the bearing are located on the same side of the cylinder block.

[0013] It can be provided that the bearing support comprises a first part and a second part assembled to the first part, the first and second parts forming between them a housing receiving the piston.

[0014] This is an interesting solution for implementing the arrangement of the invention. In particular, thanks to this two-part construction, the bearing support is simple to manufacture despite the fact that its shape can be complicated by its cooperation with the piston.

[0015] It can be provided that the second part forms a stop against the piston leaving the housing.

[0016] It can be provided that the bearing support forms a groove open towards the cylinder block, the groove receiving the piston.

[0017] The machine being revolution-symmetrical, this groove is annular. For example, it can be provided that it goes around the bearing.

[0018] It can be provided that the machine comprises a cam and fixing members passing through the cam, the periphery of the piston comprising reliefs extending in coincidence in a direction radial to the axis with zones situated between the fixing members or in an extension of these zones in a direction parallel to the axis.

[0019] Thus the reliefs preventing rotation of the piston are housed in a very space-saving manner, namely in the spaces left free by the fixing members or in the extension of these spaces in the axial direction.

[0020] It can be provided that the piston has cavities open in the direction of the axis and extending in line with the reliefs in a direction radial to the axis.

[0021] The mass of the piston is thus reduced. In addition, just as the reliefs on the bearing ensure its reinforcement, the reliefs on the piston contribute to that of the piston, in particular if they form ribs.

[0022] It can be provided that the bearing support has reliefs extending into the cavities of the piston.

[0023] Thus, these reliefs provide reinforcement of the bearing support to better absorb the forces transmitted by the shaft bearing(s).

[0024] It may be provided that the periphery of the piston and / or the bearing support have faces shaped to block rotation of the piston relative to the bearing support and resulting from forming operations without machining.

[0025] Thus, leaving these faces in the raw state makes it possible to simplify the manufacture of the machine.

[0026] It can be provided that the machine comprises a shaft carrying a stop forming obstacle to sliding of the cylinder block in the direction of the axis.

[0027] Indeed, in the absence of such an obstacle, the stress of the brake piston against the cylinder block could cause an axial displacement of the latter relative to the shaft. This stop makes it possible to avoid this risk by means of a reduced number of parts since it is the shaft which carries the stop. This avoids using a large number of parts, which would cause the accumulation of clearances across the dimension chains involved.

[0028] The invention also provides a method of manufacturing a machine according to the invention in which:

[0029] - the piston is formed otherwise than by machining, with faces of the perimeter shaped to prevent rotation of the piston relative to the bearing support, the faces being in an as-formed condition, and

[0030] - the piston is assembled to the bearing support with the faces in the as-formed state.

[0031] Thus, one avoids having to carry out one or more machining operations, particularly cutting operations (for example milling) on ​​the contoured faces shaped to prevent rotation of the piston relative to the bearing support. The manufacture of the machine is therefore simplified. However, it remains possible to produce certain parts of the piston by machining. Thus, one can carry out a deburring step and a turning step of the piston. The forming step can take place by forging or molding the piston.

[0032] The invention also provides a method of manufacturing a machine according to the invention in which:

[0033] - the bearing support is formed otherwise than by machining, with faces of the support bearings shaped to prevent rotation of the piston relative to the bearing support, the faces of the bearing support shaped to prevent rotation being in an as-formed condition, and

[0034] - the piston is assembled to the bearing support with the faces of the bearing support shaped to prevent rotation in the as-formed state.

[0035] The invention also provides a method of manufacturing a machine according to the invention in which:

[0036] - the bearing support is formed otherwise than by machining with the reliefs in a state raw forming, and

[0037] - the piston is assembled to the bearing support with the reliefs in the raw formed state.

[0038] It may be provided that the piston and / or the bearing support are machined.

[0039] It can be provided that in the method:

[0040] - an assembly is produced comprising the brake piston connected to the bearing support, and

[0041] - the assembly is mounted on a casing or a rotating part of the machine.

[0042] It may be provided that the method comprises at least one of the characteristics following:

[0043] - -the first part is assembled to the second part by interposing the piston between the first and second parts;

[0044] - at least one spring is placed in the first part and the piston is assembled second part brake with interposition of seals between the brake piston and the second part; and

[0045] - a sealing element is interposed between faces of the first and second parts located opposite each other.

[0046] This sealing can be obtained by the use of gaskets, jointing paste or any other sealing means at the interface between the parts. DESCRIPTION OF FIGURES

[0047] We will now present an embodiment of the invention by way of non-limiting example with the support of the drawings in which:

[0048] - [Fig.l] is a half-view in axial section of the principle of a machine according to a embodiment of the invention;

[0049] [Fig.2]

[0050] [Fig.3]

[0051] - figures 2 and 3 are axial sectional views of the machine according to this embodiment;

[0052] [Fig.4]

[0053] [Fig.5]

[0054] [Fig.6]

[0055] [Fig.7]

[0056] - Figures 4 to 7 are axial sectional and perspective views of certain parts of the machine of [Fig.2];

[0057] [Fig.8]

[0058] [Fig.9]

[0059] [Fig. 10]

[0060] [Fig. 11]

[0061] - Figures 8 to 11 are perspective views respectively of the first part of the bearing bracket, the brake piston and the second part of the bearing bracket of the machine of [Fig.2]; and

[0062] - [Fig. 12] is a cross-sectional view of the machine of [Fig.2] showing some of his pieces. The machine

[0063] We will describe with the support of figures 1 to 12 a rotating hydraulic machine 2 according to an embodiment of the invention.

[0064] With reference in particular to Figures 1 to 3, the machine comprises a shaft 4 having a longitudinal axis XX forming an axis of rotation of the machine. It comprises a casing 6 which comprises a bearing support 8 and a distribution cover 10 arranged on either side of a multi-lobed cam 12 to which they are rigidly fixed. It comprises two rolling bearings 14. The bearings carry the shaft 4 and bear in the radial direction to the axis XX against the bearing support 8 in shoulders of the latter. The shaft forms an output shaft and comprises a drive element at its outer end, namely a flange for a wheel or a sprocket for a chain or a track for example.

[0065] The machine comprises a cylinder block 16 visible in particular in figures 2 and 3 linked in rotation to the shaft 4 and whose structure, known in itself, has not been detailed. It has cylindrical housings radial to the axis in which are housed cam pistons mounted to slide in a radial direction and bearing on the cam 12 by means of a rolling roller.

[0066] The enclosure delimited by the casing contains a liquid at a casing pressure. A drain 13 visible in [Fig.2] allows it to be evacuated if necessary.

[0067] The machine comprises a distributor 18 extending in the axial extension of the shaft 4 and in the distribution cover 10. In a manner known per se, the distributor 18 ensures the connection of the piston housings with high pressure and low pressure fluid circuits. The machine can operate as a motor or as a pump. When it operates in motor mode, the high fluid pressure in the high pressure circuit causes the pistons to move, the rollers to roll on the multi-lobed cam 12 and ultimately the shaft 4 to rotate relative to the casing 6 in order to rotate a load secured to the shaft or the casing at the outlet. In pump mode, on the contrary, this rotation at the inlet causes the pistons to move in their housings and the fluid to be pressurized and moved in the high pressure circuit.For more details on the general structure of the machine and its operation, one can, for example, refer to the aforementioned document FR-2 765 637.

[0068] The machine comprises a brake piston 20 illustrated in particular in figures 9 and 10. It has, like most of the parts of the machine, a shape that is generally symmetrical in revolution around the axis XX. The brake piston 20 and the bearings 14 are located on the same side of the cylinder block 16 with reference to a direction of the main axis XX, as can be seen in particular in figures 1 to 3.

[0069] The brake piston 20 has a generally annular shape. It has on an axial end face 22 directed towards the cylinder block 16 a toothing comprising teeth 24 extending in projection from the face in the direction of the axis. The cylinder block 16 has on an axial end face directed towards the piston a complementary toothing comprising teeth 26.

[0070] The brake piston is received in a housing 28 of the bearing support 8. It is mounted to slide relative to the bearing support 8 in the axial direction between:

[0071] - a braking position in which the piston 20 is engaged with the block- cylinders 16 by shape complementarity so as to block a rotation of the cylinder block relative to the piston and

[0072] - a brake release position in which the piston 20 leaves the cylinder block free to rotation relative to the piston.

[0073] In the braking position, closest to the cylinder block, the teeth 24 of the piston are engaged with those of the cylinder block 16 and the shaft 4 cannot rotate relative to the casing. In the braking position, furthest from the cylinder block, the teeth of the piston are disengaged from those of the cylinder block and the shaft can rotate relative to the casing. It is therefore a dog brake.

[0074] The bearing support 8 comprises in this case a first part 30 and a second part 32 assembled to the first part, the first and second parts forming between them the housing 28. The two parts have a general annular shape with symmetry of revolution around the axis.

[0075] The first part 30 is illustrated in particular in [Fig.8]. It has a generally “U” shaped profile on one side of the axis, in section in a radial plane as in [Fig.2]. It thus has a groove 34 open in the direction of the cylinder block 16, the groove receiving the brake piston 20. This groove thus separates in the first part a peripheral portion 38, the furthest from the axis, and a central portion 40, the closest to the axis. The peripheral portion 38 bears against the cam 12 in the axial direction, unlike the central portion 40 which does not bear against the cam.

[0076] The central portion 40 is in contact with the bearings 14 which bear against its internal face 42 oriented towards the axis, against two shoulders of this central portion. A seal 44 bears on the one hand against the shaft, on the other hand against the internal face 42.

[0077] A skirt 41 of the second part 32 extends in the first part 30 in the axial direction and bears radially against the peripheral portion 38. It ensures the mutual centering of the two parts 30 and 32 of the bearing support.

[0078] As illustrated in particular in Figures 1, 6 and 7, the first and second parts 30, 32 are rigidly and directly fixed to each other by fixing members 46 extending in directions parallel to the axis, at a distance from it. In this case, each of the two parts comprises on its periphery reliefs or extensions 48. Each fixing member 46 passes through a relief 48 of the first part 30 and a relief 48 of the second part 32. These members 46 are formed in this case by screws of which a head is resting against the second part 32.

[0079] As illustrated in particular in Figures 3 and 7, the distribution cover 10, the cam 12 and the second part 32 are rigidly fixed to each other by fixing members 50 extending in directions parallel to the axis, at a distance from the latter. Each fixing member 50 passes through the distribution cover 10, the cam 12 and the second part 32. These members 50 are formed in this case by screws, one head of which bears against the distributor.

[0080] The machine 2 comprises return springs 52 tending to urge the brake piston 20 towards the cylinder block 16, therefore into the braking position. In this case, as illustrated in FIGS. 1 and 8, the first part 30 has cavities 54 formed at the bottom of the groove 34. Each spring 52 bears on the one hand against the bottom of the associated cavity 54 and on the other hand against a flat face 53 of the axial end of the brake piston 20 perpendicular to the axis and oriented towards the groove.

[0081] The machine comprises a hydraulic brake control chamber. This is a brake release chamber 56 located in the housing 28 of the bearing support 8. It is delimited by an internal periphery 57 of the second part 32 oriented in the direction of the axis and, opposite the latter, by an external periphery 59 of the piston 20 oriented in the direction opposite the axis. Two seals 61 in contact with these peripheries delimit the chamber 56. A control conduit 58 passes through the second part 32 in the direction of the axis to supply the chamber 56 with control fluid. As the chamber is delimited by flat faces 60 of the piston, visible in particular in [Fig.9], and flat faces 62 of the second part (visible in particular in [Fig.11]), all perpendicular to the axis, an adapted pressure of the fluid in the brake release chamber 56 causes the piston to move back against the springs 52 to move it into the brake release position.In this case, thanks to these opposite faces 60, 62, the second part 32 forms a stop against the piston leaving the housing 28. The bearing support is thus configured to block on its own any exit of the piston from the housing 28.

[0082] The piston 20 moves from a braking position to a braking position by a sliding movement in the second part 32.

[0083] The guidance for the axial sliding of the piston can be done by the sliding of the seals 61 on a machined surface. In the embodiment presented, the seals are carried by the brake piston (in grooves made on the outer radial part of the piston 20), but it is possible to imagine that the seals 61 are in grooves made in the internal periphery 58 oriented in the direction of the axis of the second part 32 (it is also possible to imagine that one of the seals 61 is on the piston 20 and the other seal 61 is on the second part 32). In general, the surfaces on which a groove carrying a seal is made can be machined or not; on the other hand, the surfaces on on which the seals slide (the opposing surfaces) are necessarily machined. In the embodiment described, the surfaces 71 of the piston in which the grooves are machined are machined and the surfaces 73 of the second part 32 on which the seals 61 slide are also machined.

[0084] The anti-rotation for the slide movement is done by the rough forging or demolding surfaces of the reliefs 64 of the brake piston 20 cooperating with the rough forging or demolding surfaces of the reliefs 68 of the second part 32 as will be seen.

[0085] The guidance of the braking piston 20 to slide relative to the bearing support 8 is accompanied by an anti-rotation function consisting of preventing their relative rotation. This function is ensured by shapes of the piston 20 and of the second part 32. More precisely, the external periphery 59 of the piston oriented in the direction opposite to the axis and the internal periphery 57 of the second part 32 oriented towards the axis are shaped to prevent rotation of the piston relative to the bearing support, in addition to also delimiting the braking chamber 56 as explained above.

[0086] As illustrated in particular in [Fig.9], in this case, the external periphery 59 of the piston comprises for this purpose reliefs 64 forming crenellations spaced from each other and projecting from a cylindrical face 66 of this periphery in the direction radial to the axis. In a similar and complementary manner, as illustrated in particular in [Fig.1 1], in this case, the internal periphery 57 of the second part 32 comprises for this purpose reliefs 68 forming crenellations spaced from each other and projecting from a cylindrical face 70 of this periphery in the direction radial to the axis. The reliefs 64 of the piston are arranged between those 68 of the second part. The reliefs 64, 68 thus block, by their respective lateral facets 67, 69 located in planes radial to the axis, the rotation of the piston. As will be seen below, these facets 67, 69 are in the raw forged state and do not result from a machining operation.As illustrated in figures 5 and 12, the reliefs 64 of the piston extend in this example in an extension along the axis of zones 65 forming arcs and located between the members 50 for fixing the distributor and the cam to the bearing support 8.

[0087] Each relief 64 of the piston 20 is interposed between two reliefs 68 of the second part, which means that one of the reliefs 68 comes into contact with a relief 64 of the piston during braking in one direction of rotation, and that respectively the other relief 68 comes into contact with the relief 64 during braking in the other direction of rotation. This corresponds to a machine capable of driving and braking in two directions of rotation, to operate in forward and reverse gear. The relief 64 of the piston is in contact with a relief 68 of the second part by one of its facets 67 in one braking direction, and by the other facet 67 in the other braking direction. The reliefs 64 and 68 participate in a sliding connection of the piston in the bearing support. In particular, the unmachined lateral facets 67, 69 of the reliefs 64 and 68 slide opposite each other during a braking or brake release operation. During a movement of the piston 20, the machined surfaces 64 and 70, and 71, 73 extending in the circumferential direction slide over each other.

[0088] Furthermore, as illustrated in [Fig. 10], the piston 20 has cavities 72 open in the direction of the axis and extending in line with the reliefs 64 in a direction radial to the axis. As illustrated in [Fig.8], the bearing support has reliefs 74 extending into the cavities 72 of the piston. These reliefs are located in this case on the external periphery of the central portion 40 of the first part 30 of the bearing support. These reliefs form reinforcements to absorb the forces transmitted by the bearings 14.

[0089] As illustrated in [Fig.6], the shaft 4 comprises splines 75 (shown in certain figures only - in particular in figures 4 and 6) to drive the block in rotation and this shaft 4 also carries a stop 76 forming an obstacle to sliding of the cylinder block 16 in the direction of the axis relative to the shaft. The stop is formed in this example by a disc or a washer 76 rigidly fixed to the end of the shaft coaxially with the shaft, for example by means of a screw 78. The washer extends by its external edge projecting from the cylindrical face of the shaft and opposite, in the axial direction, the face of the cylinder block 16 oriented in the opposite direction to the brake piston, in order to block the sliding of the cylinder block under the effect of the stress of the piston.The sliding locking of the cylinder block relative to the shaft can also be obtained by a stop piece force-fitted to the axial end of the shaft (for example by shrink fitting) or by a stop ring (circlip type) received in a groove of the shaft. The advantage of all the solutions presented here is that they allow controlled axial play of the cylinder block relative to the shaft. Without these stop solutions, the axial stop of the cylinder block could be made against the casing 6 or the distributor 18 but this would imply less flexibility in the chains of dimensions for the axial play of the different parts of the engine relative to each other or worse would risk damaging the distributor or the casing or even the cylinder block. Alternatively this solution would require interposing a rotating sliding member between the crankcase and the cylinder block, such as a washer of sliding material, or a ball or roller thrust bearing.The manufacturing process.

[0090] The machine 2 can be manufactured by means of an embodiment of the method of the invention which comprises the following steps.

[0091] In the preferred embodiment, the brake piston 20 illustrated in FIGS. 9 and 10 is manufactured by a forging step using a die. A forged part is more suitable for producing the brake piston 20, in particular because of the mechanical strength that is desired at its dog teeth.

[0092] During this step, the piston is forged with the cylindrical face 66 and the facets 67 of the reliefs 64 of the external periphery 59 shaped to prevent rotation of the piston relative to the bearing support 8. The piston is then extracted from its die so that these facets are in a rough forged state. Alternatively, the piston forged in the preferred embodiment and the other parts presented as molded in the preferred embodiment can be obtained by another uniaxial shaping means, such as injection molding, or sintering, along the axis XX, or in an equivalent manner, by other means such as additive manufacturing, or 3D printer. The term "forming" will be used to designate all these means of obtaining other than machining in the remainder of the description.

[0093] In this case, a step of re-machining (and particularly by turning) of certain faces of the piston is then carried out. This concerns the axial end face 53 oriented towards the bottom of the groove 34 and the cylindrical faces 71 oriented in the opposite direction to the axis, with the exception of the face 66 bearing the reliefs 64. These are the faces bearing hatching in Figures 9 and 10. All the faces of the piston not machined in this way, in particular the facets 67, are therefore left in the rough formed state (thus avoiding more costly milling operations to produce the notches).

[0094] Similarly, with reference to [Fig.8], the first part 30 of the bearing support is produced by injection molding. During this step, this part is molded with the reliefs 74 reinforcing the perimeter. This part is then demolded so that these reliefs are in a raw demolded state.

[0095] In this case, a step of re-machining (in particular by turning) of certain faces of this part 30 is then carried out. Here, on the peripheral portion, this concerns the axial end face coming into contact with the second part 32 and the opposite face. This also concerns, on the central portion, the flat and cylindrical faces forming the shoulders receiving the bearings 14. The machined faces bear hatching in [Fig.8]. All the other faces are left in the raw demolding state (thus avoiding more costly milling operations to produce the slots).

[0096] Similarly, the second part 32 of the bearing support illustrated in [Fig. 11] is produced by injection molding. During this step, this part is molded with the cylindrical face 70 and the faces 69 of the reliefs 68 of the internal periphery shaped to prevent rotation of the piston relative to the bearing support. This part is then demolded so that these faces 69 are in a raw demolded state.

[0097] In this case, a step of re-machining (in particular by turning) of certain faces of this part 32 is then carried out. These are the faces of the skirt 41, the face perpendicular to the axis coming to bear against the first part 30 and the cylindrical faces 73 against which the piston comes to bear during its sliding. The machined faces bear hatching in [Fig. 11]. All the other faces are left in the raw state of demolding, in particular the 69 facets (this avoids milling operations to create the notches).

[0098] For the piston 20, as for the first part 30 or the second part 32 of the bearing support, the surfaces of the reliefs have a draft in the axial direction, that is to say they are slightly inclined in order to allow the exit of the mold (or the forging die) along the axis XX. For example, these rough surfaces are not cylindrical along the axis XX and are in reality slightly conical. All the rough demolding (or forging) surfaces have this draft characteristic in this embodiment. The rough demolding (or forging) surfaces also have a higher roughness than the surfaces reworked by machining.

[0099] The clearance angle is typically 4° on the rough surfaces of the piston 20 as on those of the second part 32. Such a clearance angle makes it possible to limit the force required to move the piston relative to the bearing support in the brake release direction. The smaller the clearance angle, the greater the friction that must be overcome to disengage the brake piston from the second part 32 of the bearing support.

[0100] The piston 20, the first and second parts 30, 32 and the other parts of the machine are then assembled, the faces indicated above as left in the raw demolding (or forging) state remaining in this state at the time of assembly. During assembly, the first part 30 is assembled to the second part 32 by interposing the piston 20 between them so as to trap it in the housing.

[0101] The assembly of the first part 30 with the second part 32 is done by the following steps:

[0102] - insertion of the springs 52 into the cavities 54 of the groove 34 of the first part 30;

[0103] - insertion of the brake piston 20 provided with its two sealing joints 61 into the second part 32, the part 32 forming a stop making it possible to retain the brake piston 20 in one direction of movement, then

[0104] - assembly of the first part 30 provided with its springs with the second part 32 comprising the brake piston 20 equipped with its seals 61 by the screws 46. This assembly is preferably carried out in a sealed manner (by the use of a seal, joint paste, or any other sealing means at the interface between the parts 30 and 32).

[0105] Once assembled, parts 30 and 32 form a subassembly of the engine that can be mounted independently (the parts of which hold together). This subassembly is then assembled as such to the other parts of the machine.

[0106] Thus, the anti-rotation function of the piston is carried out on rough bearing surfaces. Cast (or forged) parts do not require a complicated machining step. Turning machining steps can be sufficient. This reduces the cost of manufacturing. brication.

[0107] The invention thus provides a negative parking brake of the dog type located on the same side of the cylinder block as the bearings. The sliding connection and the rotational locking of the brake piston are in this case produced between the two seals 61 within the control chamber 28.

[0108] As seen, the brake piston has specific shapes on its internal and external diameters. The internal shapes formed by the cavities 72 do not serve to stop it from rotating but serve to avoid any interference with the reliefs 74 stiffening the first part 30 of the bearing support. As the anti-rotation function of the brake piston 20 is carried out on its external periphery, a volume remains available in the bearing support to place these reinforcing reliefs 74 there and add thickness to it to solidify this part.

[0109] As the anti-rotation is done on an outside diameter of the brake piston 20, compared to a device which would have the anti-rotation of the brake piston on an inside diameter of the latter, to exert an equivalent braking torque transmitted to the cylinder block, the forces on the lateral facets of the reliefs 64, 68 are less (because the lever arm is greater).

[0110] Numerous modifications may be made to the invention without departing from its scope.

[0111] The shape of the housing 28 receiving the piston can be modified. The bearing support can be manufactured in a single part or in more than two parts.

Claims

Claims

1. Hydraulic machine (2) comprising: - a bearing support (8), - a cylinder block (16), - a brake piston (20) mounted to move relative to the bearing support between a braking position in which the piston is engaged with the cylinder block by form complementarity so as to block a rotation of the cylinder block relative to the piston and a braking position in which the piston leaves the cylinder block free to rotate relative to the piston, and - at least one bearing (14) bearing against the bearing support (8), the piston and the bearing being located on the same side of the cylinder block with reference to a direction of a main axis (XX) of the machine, a periphery (59) of the piston (20) oriented in a radial direction opposite to the axis being shaped to block a rotation of the piston relative to the bearing support.

2. Machine according to the preceding claim in which the bearing support (8) comprises a first part (30) and a second part (32) assembled to the first part, the first part and the second part forming between them a housing (28) receiving the piston.

3. Machine according to the preceding claim in which the second part (32) forms a stop against an exit of the piston from the housing.

4. Machine according to one of the preceding claims in which the bearing support (8) forms a groove (34) open towards the cylinder block, the groove receiving the piston (20).

5. Machine according to one of the preceding claims which comprises a cam (12) and fixing members (50) passing through the cam, the periphery of the piston comprising reliefs (64) extending in coincidence in a direction radial to the axis with zones (65) situated between the fixing members (50) or in an extension of these zones in a direction parallel to the axis.

6. Machine according to the preceding claim in which the piston (20) has cavities (72) open in the direction of the axis and extending in line with the reliefs (64) in a direction radial to the axis.

7. Machine according to one of the preceding claims in which the bearing support (8) has reliefs (74) extending into cavities (72) of the piston.

8. Machine according to one of the preceding claims in which the periphery of the piston and / or the bearing support have faces (67, 69) shaped to block rotation of the piston relative to the bearing support and resulting from forming operations without machining.

9. Machine according to one of the preceding claims which comprises a shaft (4) carrying a stop (76) forming an obstacle to sliding of the cylinder block (16) in the direction of the axis.

10. Method of manufacturing a machine (2) according to any one of the preceding claims, in which: - the piston (20) is formed otherwise than by machining, with faces (67) of the periphery (59) shaped to prevent rotation of the piston relative to the bearing support (8), the faces (67) being in a rough formed state, and - the piston is assembled to the bearing support with the faces in the rough formed state.

11. Method of manufacturing a machine (2) according to one of claims 1 to 9 in which: - the bearing support (8) is formed otherwise than by machining, with faces (69) of the bearing support shaped to prevent rotation of the piston (20) relative to the bearing support, the faces of the bearing support shaped to prevent rotation being in a rough formed state, and - the piston is assembled to the bearing support with the faces (69) of the bearing support shaped to prevent rotation in the rough formed state.

12. Method of manufacturing a machine according to claim 7, in which: - the bearing support (8) is formed otherwise than by machining with the reliefs (74) in a rough formed state, and - the piston is assembled to the bearing support with the reliefs in the rough formed state.

13. Method according to one of claims 10 to 12 in which the piston (20) and / or the bearing support (8) are machined.

14. Method according to one of claims 10 to 13 in which: - an assembly is produced comprising the brake piston connected to the bearing support, and - the assembly is mounted on a casing or a rotating part of the machine.

15. Method according to one of claims 10 to 14 for the manufacture of a machine according to claim 2, in which the first part (30) is assembled to the second part (32) by interposing the piston (20) between the first and second parts.

16. Method according to the preceding claim in which at least one spring is arranged in the first part (30) and the brake piston (20) is assembled to the second part (32) with the interposition of sealing joints between the brake piston and the second part.

17. Method according to one of claims 15 to 16 in which a sealing element is interposed between faces of the first and second parts located opposite each other.

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