FR3090755A1 - Texturing of surfaces - Google Patents

Abstract

The present invention relates to an operating method (E) of a hydraulic machine, said hydraulic machine comprising: a housing having a first surface, and a member movable relative to the housing, said member having a second surface in contact with the first surface , the method (E) comprising a step (E1) of setting the member in motion relative to the housing so that a sliding speed of the first surface relative to the second surface is less than 0.5 meters per second, preferably less than 0.3 meters per second, for example less than 0.15 meters per second, said step (E1) of setting in motion being implemented over a time period of setting in motion of which a duration is equal to at least 25% of the duration of a total time period of operation of the hydraulic machine, the first surface and / or the second surface comprising a texturing. Figure for the abstract: Fig. 9

Description

Description

Title of the invention: Texturing of surfaces

Technical area

The present invention relates to the field of hydraulic machines.

The present invention relates more specifically to the surface properties of elements of a hydraulic machine such as a rotary hydraulic machine with radial pistons.

Prior art

A hydraulic machine comprises several movable members with respect to housings provided for this purpose. In order to reduce the energy losses due to friction, it is known to have a lubricating fluid, typically oil, at the interface between members and housings.

With reference to FIG. 1, the behavior of the lubrication fluid differs in particular according to the sliding speed of the surfaces of the members relative to the surfaces of the housings, that is to say of the speed of the hydraulic machine. Thus, as can be seen on the solid line curve in FIG. 1, at high sliding speeds, oil wedges are formed at the interface between the members and the housings, which reduces the coefficient of friction between their surfaces . We then speak of a hydrodynamic regime. On the other hand, as also visible on the solid line curve of FIG. 1, at low sliding speeds, typically at the start of the hydraulic machine, the members are generally designed to operate dry within the housings provided for this purpose, that is to say outside the hydrodynamic regime, where the coefficient of friction between the surfaces is then higher than in the hydrodynamic regime. In this regard, provision is made to provide the members and / or the housings with friction interfaces comprising materials promoting sliding, but also to treat the surfaces brought into contact so that they have a polished, hard and / or very smooth. An example of such friction interfaces is a piston ring half-ring.

However, such operation does not bring complete satisfaction. In fact, the coefficient of friction between the surfaces remains high at low sliding speeds. In addition, the lubrication fluid is often ejected from the point of contact between member and housing at such speeds.

[0006] Thus, a hydraulic machine will have a lower yield at standstill than at a certain operating speed. In fact, the adhesion phenomena of sliding surfaces are such that the torque required to set the hydraulic machine in motion is greater when said hydraulic machine is stopped than when said hydraulic machine is in motion. Returning to FIG. 1, it can be seen that there is a sliding speed range where the hydraulic machine has a higher torque at no load, or resistance torque, or loss torque, and a poorer efficiency than from a sliding speed threshold where a hydrodynamic regime has been established.

In order to overcome this drawback, it is known to oversize the hydraulic machine, or to take into account the loss of efficiency for a hydraulic machine at start-up. However, this phenomenon is very disadvantageous for hydraulic machines which must be used around a stationary position, that is to say to maintain a torque when stationary, then operating at very low speed.

There is therefore a need to reduce friction in hydraulic machines operating outside the hydrodynamic regime.

Statement of the invention

An object of the invention is to improve the lubrication of hydraulic machines. Another object of the invention is to improve the efficiency of hydraulic machines, in particular at low speed operating speeds, typically at start-up.

Another object of the invention is to improve the operation of rotary hydraulic machines with radial pistons, in particular outside their hydrodynamic regime.

It is for this purpose proposed, according to a first aspect of the invention, a method of operating a hydraulic machine, said hydraulic machine comprising:

a housing having a first surface, and a member movable relative to the housing, said member having a second surface in contact with the first surface, the method comprising a step of setting in motion of the member relative to the housing so that that the sliding speed of the first surface relative to the second surface is less than 0.5 meters per second, preferably less than 0.3 meters per second, for example less than 0.15 meters per second, said step of setting in motion being implemented over a time period of setting in motion of which a duration is equal to at least 25% of a duration of a total time period of operation of the hydraulic machine, the first surface and / or the second surface comprising a texturing.

Advantageously, but optionally, the method according to the invention may include one of the following characteristics, taken alone or in any combination:

the method comprises a step of starting the hydraulic machine, said starting step being implemented over a starting time period of which a duration is equal to at least 20% of the duration of the total operating time period of the hydraulic machine ,

The movement of the member relative to the housing is implemented alternately in a first direction of movement and a second direction of movement, the second direction of movement being opposite to the first direction of movement,

The texturing comprises a point irregularity at a substantially continuous portion of at least one of the first and / or the second surface, and the first surface and / or the second surface comprising a texturing is a surface that is neither smooth nor polished.

According to a second aspect of the invention, use is made of texturing for at least one of a first surface of a housing of a hydraulic machine and / or a second surface of a member of the hydraulic machine, movable relative to the housing, the hydraulic machine being configured to operate so that, during at least 25% of a duration of a total time period of operation, the setting in motion of the member relative in the housing is implemented at a sliding speed of the first surface relative to the second surface which is less than 0.5 meters per second, preferably less than 0.3 meters per second, for example less than 0.15 meters per second.

According to a third aspect of the invention, the use of a hydraulic machine is proposed, said hydraulic machine comprising:

a housing having a first surface, and a member movable relative to the housing, said member having a second surface in contact with the first surface,

The hydraulic machine being configured to operate over a period of setting in motion of a duration equal to at least 25% of a duration of a total time period of operation of the hydraulic machine, during which a setting movement of the member relative to the housing is carried out at a sliding speed of the first surface relative to the second surface of less than 0.5 meters per second, preferably less than 0.3 meters per second, for example less than 0.15 meters per second, the use being characterized in that at least one of the first surface and / or the second surface comprises texturing.

According to a fourth aspect of the invention, a hydraulic machine is proposed comprising:

a housing having a first surface, a member movable relative to the housing, said member having a second surface in contact with the first surface, the first surface and / or the second surface comprising a texturing, the hydraulic machine being configured to operate according to a operating method as previously described.

Advantageously, but optionally, the hydraulic machine according to the invention can include one of the following characteristics, taken alone or in any combination:

the housing is a bore and the member is a piston, the housing is a bearing, and the member is a roller, the bearing comprises a bearing having a third surface comprising a texturing, the housing is a radially internal element of a rotary distributor, the first surface of which is a plane bearing surface, and the member is a cylinder block having a second surface attached to the plane bearing surface, the plane bearing surface and the second surface being in sliding in rotation relative to each other, the planar bearing surface and / or the second surface of the cylinder block comprising a texturing, the hydraulic machine is a hydraulic pump, the hydraulic machine is a hydraulic motor, the hydraulic machine is with radial pistons, the hydraulic machine comprises a lobed cam, the hydraulic machine comprises:

a casing formed of two lateral casing elements framing a central annular casing element, a cam comprising a lobed cam formed on a radially internal surface of the central casing element, a cylinder block mounted in relative rotation in the casing around an axis OO, facing the cam, a shaft linked in rotation with the cylinder block, guided pistons with radial sliding in respective cylinders of the cylinder block and bearing on the lobes of the cam by means of rollers, a distributor adapted to ensure a fluid connection with the cylinders of the cylinder block, so that the successive pressing of the pistons on the lobes of the cam causes the relative rotation of the cylinder block and of the elements which are linked to it relative to the casing, thanks to an asymmetry between the number of lobes of the cam and the number of pistons, the cam having a first surface, each cylinder of the cylinder block having a first surface, each roller p having a second surface, each piston having a second surface, the first surface of the cam is in contact with the second surface of each roller, the first surface of each cylinder is in contact with the second surface of the corresponding piston, and one at least first surfaces and / or second surfaces includes texturing, texturing includes a recess, texturing includes a protrusion, texturing includes a repeating pattern, and texturing includes one of the following, taken alone or in a any combination: a broken line, a chevron, a circular shape, a rectangular shape, a triangular shape, a diamond shape, and a sinusoid.

Brief description of the drawings

Other characteristics, aims and advantages of the invention will emerge from the description which follows, which is purely illustrative and not limiting, and which should be read with reference to the appended drawings in which:

[Fig.l] Figure 1, already described, illustrates schematically the evolution of the coefficient of friction between surfaces of bodies and housing surfaces of a hydraulic machine known from the prior art and examples production of a hydraulic machine according to the invention, as a function of the sliding speed, for a lubrication fluid of given viscosity, at a given load,

[Fig.2] Figure 2 schematically illustrates a longitudinal section of a hydraulic machine according to a first embodiment of the invention,

[Fig.3] Figure 3 schematically illustrates a cross section of a hydraulic machine according to a second embodiment of the invention,

[Fig.4] Figure 4 schematically illustrates a longitudinal section of a hydraulic machine according to a third embodiment of the invention,

[Fig.5] Figure 5 schematically illustrates a first embodiment of texturing according to the invention,

[Fig.6] Figure 6 schematically illustrates a second embodiment of texturing according to the invention,

[Fig.7] Figure 7 schematically illustrates a third embodiment of texturing according to the invention,

[Fig.8] Figure 8 schematically illustrates a fourth embodiment of texturing according to the invention, and

[Fig.9] Figure 9 is a flowchart illustrating steps of an operating method according to an exemplary implementation of the invention.

Description of the embodiments

Referring to the figures, we will now describe a hydraulic machine 1, a use of texturing 8 within a hydraulic machine 1, and a method E of operating a hydraulic machine 1.

A hydraulic machine 1 generally comprises a housing 20, 32 having a first surface 200, 320 and a member 52, 50 movable relative to the housing 20, 32 said member having a second surface 520, 500 in contact with the first surface 200, 320.

Such a hydraulic machine 1 can be a hydraulic motor, configured to transmit a torque as a function of a pressure difference, but also a hydraulic pump, configured to generate a pressure difference as a function of a torque. The hydraulic motor or the hydraulic pump can be hydraulic machines 1 with radial pistons 50, comprising for example a lobed cam 20.

In these different examples of hydraulic machines 1, the member may be a piston 50, and the housing may be a cylinder or a bore 32. Alternatively, or in addition, typically in hydraulic machines 1 with radial pistons 50, l the member can be a roller 52 or a shaft, and the housing can be a cam 20 or a bearing. In this case, the bearing can advantageously comprise a bearing (not shown), having a third surface.

In a particular embodiment illustrated in FIG. 2, such a hydraulic machine 1 is with a fixed casing, and comprises:

a casing 10 formed of two lateral casing elements 10a and 10c framing a central annular casing element 10b, a cam comprising a lobed cam 20 preferably formed on the radially internal surface of the central casing element 10b, a cylinder block 30 mounted in relative rotation in the casing 10 around an axis OO, opposite the cam 20, a shaft 40 linked in rotation with the cylinder block 30, for example by means of complementary axial grooves, pistons 50 guided to radial sliding in respective cylinders 32 of the cylinder block 30 and bearing on the lobes of the cam 20, preferably by means of rollers 52 and a distributor 60 adapted to ensure a fluid connection with the cylinders 32 of the cylinder block 30 ( adapted to successively apply a pressurized fluid to the pistons 50 in the case of an engine or adapted to recover a pressurized fluid from the cylinders 32 in the case of a pump), so that the successive support of the pistons 50 on the lobes of the cam 20 causes the relative rotation of the cylinder block 30 and of the elements which are linked to it relative to the casing 10, thanks to an asymmetry between the number of cam lobes 20 and the number of pistons 50.

As shown in Figure 2, the dispenser 60 comprises two concentric complementary elements 62, 66, respectively radially internal and radially external. These two elements 62, 66 can be indexed for rotation, or linked to rotation by any suitable means, but they are capable of relative axial displacement. For example, as illustrated in FIG. 2, a fork-shaped protuberance of the part 62 frames a pin linked to the element 66, which ensures indexation in rotation only of these two parts, without interfering with the other possible movements. of the element 62 vis-à-vis the element 66. In general, the distributor part in contact with the cylinder block must be indexed in rotation relative to the cam of the hydraulic machine.

The radially external element 66 of the distributor belongs to the casing element 10a and constitutes a secondary distributor element or secondary fluid connection element. The radially internal element 62, which constitutes the main distributor element, has a face 63 transverse to the axis OO, which constitutes a planar support surface, sometimes called "glass", attached to a face 33 complementary to the block cylinders 30. Each of these two distributor elements 62, 66 comprises channels intended to ensure the routing of the oil between the cylinders 32 and the exterior of the hydraulic machine. Such a hydraulic machine is described for example in the documents LR 2 651 836, LR 2 582 058 and EP 2 531 720.

The radially external element 66, which constitutes the secondary distributor element, has at least two channels 67, 68 generally radial, which open at the interface between the two elements 62 and 66, preferably in annular grooves 71, 73 formed at this interface between the two elements 62 and 66. The radially internal element 62, which constitutes the main distributor element, has generally axial channels 61, 64 which open onto the face 63 of the main distributor element forming the flat support surface, sometimes called "glass". These axial channels 61, 64 are extended by any suitable secondary channels, generally generally radial, to ensure a fluid connection between these axial channels 61, 64 and the channels 67, 68 of the element 66.

Sealing means are provided between the two distributor elements 62 and 66. More specifically, it is thus preferably provided at least three seals 70, 72 and 74 distributed axially between the two distributor elements 62 and 66. The pair of seals 70 and 72 surround a groove 71 formed at the interface between the elements 62 and 66 and which provide a connection between the channels 61 and 67. The second pair of seals 72 and 74 frame a groove 73 formed at the interface between the elements 62 and 66 and which provide a connection between the channels 64 and 68.

Channels 67 and 68 form for example a high pressure line and a drain and are for example connected to a source of pressurized fluid and to a pressureless tank, in the case of an engine.

There is shown in Figure 4 appended in longitudinal section, a variant of a hydraulic machine with radial pistons of the aforementioned type with mobile housing for rotation. This variant can be in accordance with the cross-sectional representation illustrated in FIG. 3. Such a machine is described for example in document EP 0 487 393.

The hydraulic machine illustrated in FIG. 4 also includes:

a casing 10 formed of two lateral casing elements 10a and 10c framing a central annular casing element 10b, a cam comprising a multi-lobed cam 20 preferably formed on the radially internal surface of the central casing element 10b, a cylinder block 30 mounted in relative rotation in the casing 10 around an axis OO, a shaft 40 linked in rotation with the cylinder block 30, pistons 50 guided in radial sliding in respective cylinders 32 of the cylinder block 30 and bearing on the lobes of the cam 20, preferably by means of rollers 52 and a distributor 60 adapted to ensure a fluid connection with the cylinders 32, for example successively applying a pressurized fluid to the pistons 50 in the case of an engine , so that the successive support of the pistons 50 on the lobes of the cam 20 causes the relative rotation of the cylinder block 30 and of the elements which are linked to it relative to the casing 10, thanks to a diss asymmetry between the number of cam lobes 20 and the number of pistons 50.

Found in the alternative embodiment illustrated in Figure 4, a distributor 60 comprising two concentric complementary elements 62, 66, respectively radially external and radially internal. The radially internal distributor element 66 constitutes the secondary distributor element. It is linked in rotation with the shaft which is also linked in rotation with the cylinder block 30, and can even be formed in this shaft 40. The radially external element 62, which constitutes the main distributor element, has a face 63 transverse to the axis 0-0 which constitutes a planar support surface, sometimes called "glass", attached to a complementary face 33 of the cylinder block 30. Again the two elements 62, 66 are linked in rotation by all appropriate means, but they are capable of relative axial displacement along the axis OO.

Each of these two distributor elements 62, 66 comprises channels intended to ensure the routing of the oil between the cylinders 32 and the outside of the machine. The radially internal element 66, which constitutes the secondary distributor element, has at least two generally radial channels 67, 68 which open at the interface between the two elements 62 and 66, preferably in annular grooves 71, 73 formed at this interface between the two elements 62 and 66. These channels 67, 68 communicate with the outside of the machine, typically with a pressure source and a drain, by any appropriate means, preferably by the intermediary channels 670, 680 formed axially in the shaft 40. The radially external element 62, which constitutes the main distributor element, also has globally axial channels 61, 64 which open on the face 63 of the main element dispenser forming the flat support surface, sometimes called "ice". These axial channels 61, 64 are extended by any suitable secondary channels, generally generally radial, to ensure a fluid connection between these axial channels 61, 64 and the channels 67, 68 of the element 66.

Also here again, sealing means are provided between the two distributor elements 62 and 66. More precisely, it is thus preferably provided at least three seals 70, 72 and 74 distributed axially between the two distributor elements 62 and 66. The pair of seals 70 and 72 surround the groove 71 formed at the interface between the elements 62 and 66 and which provide a connection between the channels 61 and 67. The second pair of seals 72 and 74 surround the groove 73 formed at the interface between the elements 62 and 66 and which provide a connection between the channels 64 and 68.

The channels 67 and 68 form for example a high pressure line and a drain and are for example connected to a source of pressurized fluid and to a pressureless reservoir, in the case of an engine, via the channels 670 and 680. Channels 67 and 68 can also be the high pressure and low pressure lines of a closed loop circuit.

The sealing means 70, 72 and 74 currently used in hydraulic machines are generally formed of open or split C-shaped metal segments, for example of cast iron segments. More precisely to obtain the seal which a single segment does not make it possible, taking into account the presence of the cut essential for ensuring the engagement of the segments on the dispenser due to their low deformability, the sealing means are generally formed by two associated segments placed respectively in two neighboring housings.

The embodiments of hydraulic machine 1 illustrated in Figures 2 to 4 are rotary hydraulic machines with radial pistons. As can be seen in these figures, in hydraulic machine 1:

the cam 20 has a first surface 200, each cylinder 32 of the cylinder block 30 has a first surface 320, each roller 52 has a second surface 520, each piston 50 has a second surface 500, the first surface 200 of the cam 20 is in contact with the second surface 520 of each roller 52, and the first surface 320 of each cylinder 32 is in contact with the second surface 500 of the corresponding piston 50.

In any event, at least one of the first surface 200, 320, the second surface 520, 500, and / or the third surface, includes a texturing 8. In one embodiment, the face 63 transverse of the internal radial element 62, which constitutes the planar bearing surface, and / or the face 33 complementary to the cylinder block 30, comprises a texturing 8. In this embodiment, the internal radial element 62 is the housing , and the cylinder block 30 is the member movable relative to the housing 62.

By texturing is meant a point irregularity at a substantially continuous surface. In other words, a surface with texturing is neither smooth nor polished. A surface comprising a texturing can, moreover, be a smooth sliding surface to which a texturing has been added.

Texturing 8 can take various forms. Typically, it can appear as a protrusion, or a hollow, made within the surface, as visible in FIG. 5. Alternatively, it can appear as a protuberance, an elevation or a protrusion, protruding from the surface, as also visible in FIG. 5. The dimensions of a recess or a protuberance forming texturing 8 can vary depending on the desired lubrication properties. In addition, the texturing 8 of a surface can follow a repeated pattern, for example a sinusoid, as visible in FIG. 6, or a plurality of shapes distributed uniformly or not on the surface, or even randomly distributed on the surface, as visible in FIG. 7. Alternatively, or in addition, the texturing 8 may include one of the following elements, taken alone or in any combination: a broken line (FIG. 6), a chevron (FIGS. 7 and 8), a rectangular shape (Figures 5 and 7), a circular shape (Figures 5 and 7), a diamond shape (Figure 7), a triangular shape (Figure 7).

Such texturing 8 is generally carried out during the manufacture of the member 52, 50 and / or of the housing 20, 32. In this regard, the manufacturing process comprises a step of modifying the first surface 200, 320 , of the second surface 520, 500, and / or of the third surface. Such a modification step can then be implemented by deformation of said surface 200, 320, 520, 500 typically by rolling or by pressing of said surface 200, 320, 520, 500, but also by punctual cutting, typically by cutting or by laser engraving. In any event, the modification step essentially depends on the material of the surfaces 200, 320, 520, 500. Typically, such surfaces 200, 320, 520, 500 can comprise synthetic material, or metallic, for example steel, such as nitrided steel. The third surface can, for its part, comprise plastic and / or thermoplastic resin.

Returning to FIG. 1, the use of such texturing 8 on the first surface 200, 320, the second surface 520, 500, and / or the third surface results, outside the hydrodynamic regime, in a lowering of the coefficient of friction at the contact between said surfaces 200, 320, 520, 500, as visible on the dotted curves of FIG. 1. Indeed, such texturing 8 allows an advantageous accumulation of oil in the zone where She's spreading. In addition, such a texturing 8 makes it possible to generate disturbances, such as vortices, in the flow of the lubrication fluid. Thus, the starting efficiency of the hydraulic machine 1 can in particular be improved. In other words, as can be seen on the dotted curves in FIG. 1, the hydrodynamic regime is reached more quickly, that is to say at a lower sliding speed compared to a hydraulic machine comprising surfaces of smooth sliding (ie without texturing), all other things being equal.

More specifically, the use of such texturing 8 is advantageous for hydraulic machines 1 operating over at least 25% of a duration of a total operating time period, at a speed such as the speed of sliding of the first surface 200, 320 in relation to the second surface 520, 500 or, where appropriate, in relation to the third surface, is less than 0.5 meters per second, preferably less than 0.3 meters per second , for example less than 0.15 meters per second. Indeed, the border between hydrodynamic regime and mixed regime (i.e. outside the hydrodynamic regime) depends on the viscosity of the lubrication fluid, but also on the contact pressure. Thus, by way of nonlimiting example, for a contact pressure substantially equal to 150 bars and an average viscosity at 80 ° C:

the coefficient of friction between a second surface 520 of the hydraulic machine 1 (typically that of the roller 52), and a third surface (typically that of the bearing) stabilizes from a sliding speed equal to 0.3 meters per second , and the coefficient of friction between the first surface 320 of the hydraulic machine 1 (typically that of the bore 32) and the second surface 500 (typically that of the piston 52) stabilizes from a sliding speed equal to 0 , 15 meters per second.

The total operating time period of a hydraulic machine 1 corresponds to the sum of the operating time periods of the hydraulic machine 1, each operating time period corresponding to the time period extending between a start and a stop of the hydraulic machine 1 which are consecutive. The number of operating time periods taken into account in the sum is taken arbitrarily over a significant life cycle of the hydraulic machine 1, typically between two maintenance operations of the hydraulic machine 1. Thus, the use of such texturing 8 reduces the friction between the member 52, 50 and the housing 20, 32 when the hydraulic machine 1 operates in dry conditions, that is to say outside the hydrodynamic regime.

Such use is advantageous for slow hydraulic machines 1, implementing a high torque. More precisely, the hydraulic machines 1 operating at a speed lower than 60 revolutions per minute and / or implementing stop and restart cycles every 20 seconds, thus see the coefficient of friction at the interface between the first surface 200, 320 and the second surface 520, 500 or, where appropriate, the third surface, reduced compared to hydraulic machines having smooth surfaces. Under hydrodynamic conditions, the presence of such texturing 8 does not modify, on the other hand, the lubricating properties of the lubricating fluid.

Such use is particularly advantageous for a hydraulic machine 1 with radial pistons and a multi-lobed cam as illustrated in FIGS. 2 to 4. Indeed, such a type of hydraulic machine 1 develops high torque at rotational speeds. weak, and works with direct drive, that is to say without reducer, by being connected to a machine making multiple stops, reciprocating movements and drives at very low speed.

Such use is particularly advantageous for driving machines doing millimeter work (or "inching" or "creep drive" in English terminology), that is to say advancing a few millimeters per second up to the speed of a man walking.

Such use is particularly advantageous for the driving of machines making starts at a standstill and at maximum torque, for example machines which must hold the force at a standstill and then move. For example a machine doing a millimeter work on a slope, which would slow down to a stop, which would hold in position and then restart slowly. In particular, this use makes it possible to reduce the torque necessary to put the machine in rotation from a standstill. In other words, it allows the hydraulic machine 1 to rotate from a lower pressure, which amounts to improving the efficiency of the machine at zero speed.

Such use can advantageously be implemented for the benefit of hydraulic machines 1 used for site engines (eg mechanical shovel, compactor) operating at reduced speed, but with large variations in sliding speed around the zero speed. . Without texturing 8, the oil wedge would typically not have time to form at the interface between the members 52, 50 and the corresponding housings 20, 32 of such hydraulic motors 1. Thanks to texturing 8, on the contrary, the lowering of the coefficient of friction is favored outside the hydrodynamic regime.

In addition, such use is also used in the operation of hydraulic machines 1 operating in an alternating movement. More specifically, such use promotes lubrication at the interface between the first surface 200, 320 and the second surface 520, 500 or, where appropriate, the third surface, when the member 52, 50 is set in motion relative to to the housing 20, 32 alternately in a first direction of movement and a second direction of movement, the first direction of movement being opposite to the second direction of movement. Such a movement can moreover be jerky, that is to say that the member 52, 50 can be set in motion according to the first direction of movement, then be immobilized, before being set in motion again, this time in the second direction of movement.

An operating method E of such a hydraulic machine 1 thus comprises a step El of setting in motion the member 52, 50 relative to the housing 20, 32 so that a sliding speed of the first surface 200, 320 relative to the second surface 520, 500 is less than 0.5 meters per second, preferably less than 0.3 meters per second, for example less than 0.15 meters per second, said step E1 of setting in motion being implemented over a time period of setting in motion of which a duration is equal to at least 25% of a duration of a total time period of operation of the hydraulic machine 1. Thanks to the texturing 8 of the first surface 200, 320 and / or the second surface 520, 500, the formation of an oil wedge is favored whatever the sliding speed of the first surface 200, 320 relative to the second surface 520, 500.

Advantageously, such an operating method E comprises a starting step E2 of the hydraulic machine 1, said starting step E2 being implemented over a starting time period of which a duration is equal to at least 20% of the duration of the total operating period of the hydraulic machine 1. In other words, such an operating method E is implemented on a hydraulic machine 1 having to undergo regular starting and stopping cycles. In this case, the texturing 8 promotes lubrication of the interface between the member 52, 50 and the housing 20, 32, despite the high starting rate of the hydraulic machine 1, which therefore rarely reaches the hydrodynamic regime.

In one embodiment, the movement El of the member 52, 50 relative to the housing 20, 32 is implemented alternately in a first direction of movement and a second direction of movement, the second direction of movement being opposite to the first direction of movement. The efficiency of the lubrication is thus favored for hydraulic machines 1 operating in an alternative mode, that is to say typically the hydraulic machines used within site instruments.

Claims (1)

Claims [Claim 1] Operating method (E) of a hydraulic machine (1), said hydraulic machine (1) comprising: a housing (20, 32) having a first surface (200, 320), and a member (52, 50) movable relative to the housing (20, 32), said member (52, 50) having a second surface (520, 500) in contact with the first surface (200, 320), the method (E) comprising a step (El) of setting in motion the member (52, 50) relative to the housing (20, 32) so that a sliding speed of the first surface (200, 320) relative to the second surface (520, 500) is less than 0.5 meters per second, preferably less than 0.3 meters per second, for example less than 0.15 meters per second, said step (El) of setting in motion being implemented over a time period of setting in motion of which a duration is equal to at least 25% of a duration of a total time period of operation of the hydraulic machine (1), the first surface ( 200, 320) and / or the second surface (520, 500) comprising a texturing (8). [Claim 2] Operating method (E) according to claim 1, comprising a step (E2) of starting the hydraulic machine (1), said starting step (E1) being implemented over a starting time period whose duration is equal to at least 20% of the duration of the total operating period of the hydraulic machine (D- [Claim 3] Operating method (E) according to one of claims 1 and 2, wherein the setting in motion of the member (52, 50) relative to the housing (20, 23) is implemented alternately in a first direction of movement and a second direction of movement, the second direction of movement being opposite to the first direction of movement. [Claim 4] Operating method (E) according to one of claims 1 to 3, wherein the texturing (8) comprises a point irregularity at a substantially continuous portion of at least one of the first (200, 320) and / or the second surface (520, 500). [Claim 5] Operating method (E) according to one of claims 1 to 4, wherein the first surface (200, 320) and / or the second surface (520, 500) comprising a texturing (8) is a surface which is not neither smooth nor polished. [Claim 6] Use of a texturing (8) for at least one of a first surface (200, 320) of a housing (20, 32) of a hydraulic machine (1) and / or a second surface (520, 500) d 'a member (52, 50) of the hydraulic machine (1), movable relative to the housing (20, 32), the hydraulic machine (1) being configured to operate so that, during at least 25% of a duration of a total time period of operation, the setting in motion of the member (52, 50) relative to the housing (20, 32) is implemented at a sliding speed of the first surface (200, 320 ) relative to the second surface (520, 500) which is less than 0.5 meters per second, preferably less than 0.3 meters per second, for example less than 0.15 meters per second. [Claim 7] Use of a hydraulic machine (1), said hydraulic machine (1) comprising: a housing (20, 32) having a first surface (200, 320), and a member (52, 50) movable relative to the housing (20, 32), said member (52, 50) having a second surface (520, 500) in contact with the first surface (200, 320), the hydraulic machine (1) being configured to operate over a period of setting in motion of a duration equal to at least 25% of a duration of a total time period of operation of the hydraulic machine, during which a setting movement of the member (52, 50) relative to the housing (20, 32) is carried out at a sliding speed of the first surface (200, 320) relative to the second surface (520, 500) less than 0, 5 meters per second, preferably less than 0.3 meters per second, for example less than 0.15 meters per second, the use being characterized in that at least one of the first surface (200, 320) and / or the second surface (520, 500) comprises a texturing (8). [Claim 8] Hydraulic machine (1) comprising: a housing (20, 32) having a first surface (200, 320), and a member (52, 50) relative to the housing (20, 32), said member (52, 50) having a second surface (520, 500 ) in contact with the first surface (200, 320), the first surface (200, 320) and / or the second surface (520, 500) comprising a texturing (8), the hydraulic machine (1) being configured to operate according to an operating method (E) according to one of claims 1 to 5. [Claim 9] Hydraulic machine (1) according to claim 8, wherein the housing (20, 32) is a bore and the member (52, 50) is a piston. [Claim 10] Hydraulic machine (1) according to claim 8, wherein the housing (20, 32) is a bearing, and the member (52, 50) is a roller. [Claim 11] Hydraulic machine (1) according to claim 10, wherein the bearing (20, 32) comprises a bearing having a third surface comprising a texturing (8). [Claim 12] Hydraulic machine (1) according to claim 8, in which the housing (20, 32) is a radially internal element (62) of a rotary distributor whose first surface is a plane bearing surface (63), and the member is a cylinder block (30) having a second surface (33) attached to the planar support surface (63), the planar support surface (63) and the second surface (33) being in sliding in relative rotation l relative to each other, the planar bearing surface (63) and / or the second surface (33) of the cylinder block (30) comprising a texturing (8). [Claim 13] Hydraulic machine (1) according to one of claims 8 to 12, in which the hydraulic machine (1) is a hydraulic pump. [Claim 14] Hydraulic machine (1) according to one of Claims 8 to 13, in which the hydraulic machine (1) is a hydraulic motor. [Claim 15] Hydraulic machine (1) according to one of claims 8 to 14, in which the hydraulic machine (1) is with radial pistons. [Claim 16] Hydraulic machine (1) according to one of claims 8 to 15, wherein the hydraulic machine (1) comprises a lobed cam. [Claim 17] Hydraulic machine (1) according to one of claims 8 to 16, comprising: a casing (10) formed by two lateral casing elements (10a, 10c) framing a central annular casing element (10b), a cam comprising a lobed cam (20) formed on a radially internal surface of the central casing element (10b), a cylinder block (30) mounted for relative rotation in the casing (10) about an axis (O-O), facing the cam (20), a shaft (40) linked in rotation with the cylinder block (30), pistons (50) guided in radial sliding in respective cylinders (32) of the cylinder block (30) and bearing on the lobes of the cam (20) by means of rollers (52), a distributor (60) adapted to ensure a fluid connection with the cylinders (32) of the cylinder block (30), so that the successive support of [Claim 18] [Claim 19] [Claim 20] [Claim 21] pistons (50) on the cam lobes (20) causes the relative rotation of the cylinder block (30) and of the elements linked to it with respect to the casing (10), thanks to an asymmetry between the number of lobes of the cam (20) and the number of pistons (50), the cam (20) having a first surface (200), each cylinder (32) of the cylinder block ( 30) having a first surface (320), each roller (52) having a second surface (520), each piston (50) having a second surface (500), the first surface (200) of the cam (20) is in contact with the second surface (520) of each roller (52), the first surface (320) of each cylinder (32) is in contact with the second surface (500) of the corresponding piston (50), and at least one first surfaces (200, 320) and / or second surfaces (520, 500) include texturing (8). Hydraulic machine (1) according to one of claims 8 to 17, wherein the texturing (8) comprises a recess. Hydraulic machine (1) according to one of claims 8 to 18, in which the texturing (8) comprises a protuberance. Hydraulic machine (1) according to one of claims 8 to 19, in which the texturing (8) comprises a repeated pattern. Hydraulic machine (1) according to one of claims 8 to 20, in which the texturing (8) comprises one of the following elements, taken alone or in any combination: a broken line, a chevron, a circular shape, a rectangular shape, a triangular shape, a diamond shape, and a sinusoid.