EP3234359B1 - Hydraulic device with radial pistons comprising at least one ball bearing - Google Patents

Description

GENERAL TECHNICAL FIELD

The present invention relates to the field of hydraulic apparatus. More specifically, the present invention relates to the field of hydraulic devices with radial pistons.

STATE OF THE ART

The figure 1 illustrates a longitudinal sectional view of a radial piston hydraulic apparatus 1 according to a prior art. A similar radial piston hydraulic apparatus is for example described in the document FR 2 955 903 .

The hydraulic apparatus 1 comprises a shaft 2 disposed along an axis of rotation 3 and a cover 4 forming a housing element, free to rotate relative to each other.

The hydraulic apparatus 1 further comprises an assembly comprising a multilobe cam 5, a cylinder block 6, and a distributor 7.

The cam 5 is formed of a ring formed in the cover 4 and comprises, on a radially internal surface, a series of generally sinusoidal-like lobes equi-distributed around the axis of rotation 3.

The cylinder block 6 is placed inside the ring forming the cam 5 and defines a plurality of cylinders oriented radially with respect to the axis of rotation 3 and opening onto an outer peripheral face of the cylinder block 6 opposite the cam 5. A piston is mounted with radial sliding respectively in each of the cylinders. Each piston bears on the radially inner surface of the cam 5.

The distributor 7 is adapted to apply in a controlled manner a fluid under pressure successively on each of the pistons, more specifically in an internal chamber of the cylinders adjacent to the pistons, so that the successive support of the pistons on the lobes of the cam 5 causes the relative rotation of the cylinder block 6 and the elements which are connected to it with respect to the cam 5 and thus to the cover 4 or vice versa. To this end, there is an asymmetry between the number of lobes formed on the cam 5 and the number of associated pistons located in the cylinder block 6.

The hydraulic apparatus 1 also comprises two tapered roller bearings 8a and 8b by means of which the shaft 2 and the cover 4 are mounted rotating with respect to each other. To this end, the bearings 8a and 8b are mounted in radial contact with the shaft 2 on the one hand and the lid 4 on the other hand, and are arranged on either side of the assembly formed by the cam 5. , the cylinder block 6 and the distributor 7. Each bearing 8a and 8b is also mounted between two axial abutment surfaces formed in the shaft 2 and the cover 4.

However, the tapered roller bearings 8a and 8b need to be mounted without axial play, so as to ensure the recovery of the axial forces in the hydraulic device 1 and prevent the bearings 8a and 8b from disengaging.

For this, it is in particular necessary to place preload washers 9a or spring rings 9b in axial contact with the bearings 8a and 8b. The precharge washers 9a or the elastic rings 9b are for example in axial contact with the bearings 8a and 8b on the one hand and with the axial abutment surface of the cover 4 on the other hand, so as to press the bearings 8a and 8b against the axial abutment surface of the shaft 2, and thus ensure a mounting without axial play of the tapered roller bearings 8a and 8b in the hydraulic apparatus 1.

However, the preload washers 9a or the elastic rings 9b generate a preload force which induces a drag at the bearings 8a and 8b, thus reducing their life.

The use of tapered roller bearings therefore requires them to be replaced frequently.

Furthermore, the rollers of the bearings 8a and 8b are conventionally bathed in a lubricating oil intended to reduce the friction between the rollers and the inner and outer rings of the bearings 8a and 8b.

However, by rolling on the inner and outer rings of the bearings 8a and 8b, the rollers move the lubricating oil, thereby generating additional drag on the bearings 8a and 8b.

There is therefore a need to reduce the drag induced by the tapered roller bearings 8a and 8b of the hydraulic apparatus 1.

Another type of engine, illustrated by the document FR 2,588,616 includes two bearings, one of which may be conical, on the same side of a dispenser.

PRESENTATION OF THE INVENTION

• un arbre disposé selon un axe ;
• un couvercle formant un élément de carter, le couvercle et l'arbre étant libres en rotation l'un par rapport à l'autre ;
• un ensemble de distribution comprenant :
  • une came multilobes ;
  • un bloc cylindres agencé radialement en regard de la came, ledit bloc cylindres comprenant une pluralité de cylindres dans lesquels sont disposés des pistons guidés à coulissement radial dans des cylindres respectifs du bloc cylindres et prenant appui sur les lobes de la came ;
  • un distributeur configuré pour exercer un effort de poussée contre le bloc cylindres selon l'axe de l'arbre de sorte à appliquer successivement un fluide sous pression sur lesdits pistons ;
• un premier roulement mécanique monté en contact radial entre le couvercle et l'arbre, le premier roulement mécanique étant un roulement à billes à contact droit,
• un ensemble de deuxièmes roulements mécaniques comprenant au moins un deuxième roulement mécanique monté en contact radial entre le couvercle et l'arbre, ledit ensemble de deuxièmes roulements mécaniques étant configuré pour reprendre l'effort de poussée exercé par le distributeur,
  dans lequel le premier roulement mécanique et l'ensemble de deuxièmes roulements mécaniques sont disposés de part et d'autre de l'ensemble de distribution .

The object of the present invention is to solve the problems previously described by proposing a hydraulic device with radial pistons comprising:

• a shaft arranged along an axis;
• a cover forming a housing element, the cover and the shaft being free to rotate relative to each other;
• a distribution set comprising:
  • a multilobe cam;
  • a cylinder block arranged radially opposite the cam, said cylinder block comprising a plurality of cylinders in which pistons are arranged guided to radial sliding in respective cylinders of the cylinder block and bearing on the lobes of the cam;
  • a distributor configured to exert a thrust force against the cylinder block along the axis of the shaft so as successively to apply a fluid under pressure on said pistons;
• a first mechanical bearing mounted in radial contact between the cover and the shaft, the first mechanical bearing being a straight contact ball bearing,
• a set of second mechanical bearings comprising at least one second mechanical bearing mounted in radial contact between the cover and the shaft, said set of second mechanical bearings being configured to take up the thrust force exerted by the distributor,
  wherein the first mechanical bearing and the set of second mechanical bearings are arranged on either side of the distribution assembly.

Preferably, the shaft comprises an axial abutment surface against which the cylinder block is pushed, when the distributor exerts the thrust force against the cylinder block.

Preferably, the second mechanical bearing is a tapered roller bearing or an angular contact ball bearing.

Preferably, the second mechanical bearing comprises an outer cage and an inner cage between which rolling elements are mounted, axially opposite sides of the inner cage and the outer cage being respectively mounted in axial contact with the shaft and the cover, so to resume the pushing effort.

Preferably, the hydraulic apparatus comprises a sleeve rotatably mounted around the shaft and through which the second mechanical bearing is mounted in radial contact and in axial contact with the shaft.

Preferably, the set of second mechanical bearings comprises a ball bearing with right contact and a thrust ball.

Preferably, the thrust bearing comprises a first cage and a second cage between which balls are mounted, and the right contact ball bearing of the assembly comprises an inner cage and an outer cage between which balls are mounted, the first cage being mounted in axial contact with the shaft, and axially opposite sides of the outer race of the right contact ball bearing of the assembly being respectively mounted in axial contact with the second cage of the thrust bearing and the cover, so as to resume the pushing force.

Preferably, the set of second mechanical bearings comprises a needle bearing and a cylindrical roller stop.

Preferably, the cylindrical roller stopper comprises a first cage and a second cage between which cylindrical rollers are mounted, the first cage of the cylindrical roller stopper being mounted in axial contact with the lid and the second cage of the cylindrical roller thrust bearing. being mounted in axial contact with the cylinder block, on the sides radially opposite the first cage and the second cage of the cylindrical roller stop being respectively mounted in radial contact with the lid and the cylinder block.

Preferably, the needle bearing comprises an inner race and an outer race between which needles are mounted, axially opposite sides of the inner race of the needle bearing being respectively mounted in axial contact with the shaft and the cover, and on the sides. axially opposite the outer race of the needle bearing being mounted in axial contact with the cover.

Preferably, the hydraulic apparatus comprises a sleeve rotatably mounted around the shaft and through which the needle bearing is mounted in radial contact and in axial contact with the shaft.

Preferably, the set of second mechanical bearings is mounted without axial play between the shaft and the cover.

Preferably, the outer race of the second mechanical bearing is mounted in axial contact with the cover via a preloading washer, so as to ensure the assembly without axial play of the set of second mechanical bearings between the shaft and lid.

Preferably, the outer race of the right contact ball bearing of the assembly is mounted in axial contact with the second cage of the thrust bearing by means of a preloading washer, so as to ensure the assembly without axial play. of the set of second mechanical bearings between the shaft and the cover.

Preferably, the set of second mechanical bearings is positioned on a first side of the distribution assembly disposed in the thrust direction of the distributor against the cylinder block.

Preferably, the hydraulic apparatus comprises two first mechanical bearings arranged on either side of the distribution assembly, said first mechanical bearings being right contact ball bearings.

Preferably, the first mechanical bearing is positioned on a second side of the distribution assembly disposed opposite the thrust direction of the distributor against the cylinder block.

Preferably, the first mechanical bearing comprises an inner cage and an outer cage between which balls are mounted, axially opposite sides of the outer cage and the inner cage being respectively mounted in axial contact with the lid and the shaft, so that to obtain a looping of the axial forces by the cover.

Preferably, the set of second mechanical bearings is positioned on the second side of the dispensing assembly disposed opposite the direction of thrust of the dispenser against the cylinder block.

Preferably, the first mechanical bearing is positioned on the first side of the distribution assembly disposed in the thrust direction of the distributor against the cylinder block.

Preferably, the first mechanical bearing comprises an inner cage and an outer cage between which balls are mounted, axially opposite sides of the inner cage being both mounted in axial contact with the shaft, so as to ensure a closure of the forces by the tree.

Preferably, the shaft is hollow and configured to be mounted around a shaft, in particular a differential shaft, said hydraulic apparatus comprising a first annular seal mounted in radial contact with an outer surface of one end of the shaft. a part and the lid on the other hand and a second annular seal mounted in radial contact with an inner surface of said end of the shaft on the one hand and configured to be mounted in radial contact with the other shaft.

Preferably, the hydraulic apparatus comprises a hoop comprising a first and a second annular portion and connected to one another by an intermediate portion, the first annular portion of the hoop being mounted on the outer surface of the end of the hinge. shaft, and the first annular seal being mounted in radial contact with the end of the shaft via said first annular portion, the second annular portion of the hoop extending from the intermediate portion away from the end of the shaft, and the second annular seal being mounted in radial contact with the end of the shaft by the intermediate of said second annular portion.

Preferably, the inner surface of the end of the shaft is provided with a shoulder forming a space which accommodates the second annular seal.

Preferably, the hydraulic apparatus further comprises an annular band mounted on the outer surface of the end of the shaft and through which the first annular seal is in radial contact with the end of the shaft.

Preferably, the outer surface of the end of the shaft is provided with a shoulder accommodating the first part of the hoop or the ring hoop.

Preferably, the first and second annular seals are generally arranged around each other.

PRESENTATION OF FIGURES

• la figure 1 montre une vue schématique partielle, en coupe, d'un appareil hydraulique selon l'art antérieur ;
• la figure 2 montre une vue schématique partielle, en coupe, d'un exemple d'appareil hydraulique selon un premier mode de réalisation de l'invention ;
• la figure 3 montre une vue schématique partielle, en coupe, d'un autre exemple d'appareil hydraulique selon le premier mode de réalisation de l'invention ;
• la figure 4 montre une vue schématique partielle, en coupe, d'un autre exemple d'appareil hydraulique selon le premier mode de réalisation de l'invention ;
• la figure 5 montre une vue schématique partielle, en coupe, d'un autre exemple d'appareil hydraulique selon le premier mode de réalisation de l'invention ;
• la figure 6 montre une vue schématique partielle, en couple, d'un exemple d'appareil hydraulique selon un deuxième mode de réalisation de l'invention, ledit appareil hydraulique étant en configuration embrayée ;
• la figure 7 montre une vue schématique partielle, en coupe, de l'appareil hydraulique illustrée à la figure 6 en configuration débrayée ;
• la figure 8 montre une vue schématique partielle, en coupe, d'une variante de réalisation de l'appareil hydraulique illustré à la figure 6 ;
• la figure 9 montre une vue schématique partielle, en coupe, d'un dispositif d'étanchéité de l'appareil hydraulique illustré à la figure 2 ;
• la figure 10 montre une vue schématique partielle, en coupe, d'une variante du dispositif d'étanchéité illustré à la figure 9 ;
• la figure 11 montre une vue schématique partielle, en coupe, d'une variante du dispositif d'étanchéité illustré à la figure 10.

Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and nonlimiting, and which should be read with reference to the appended drawings, in which:

• the figure 1 shows a partial schematic view, in section, of a hydraulic apparatus according to the prior art;
• the figure 2 shows a partial schematic view, in section, of an exemplary hydraulic apparatus according to a first embodiment of the invention;
• the figure 3 shows a partial schematic sectional view of another example of a hydraulic apparatus according to the first embodiment of the invention;
• the figure 4 shows a partial schematic sectional view of another example of a hydraulic apparatus according to the first embodiment of the invention;
• the figure 5 shows a partial schematic sectional view of another example of a hydraulic apparatus according to the first embodiment of the invention;
• the figure 6 shows a partial schematic view, in torque, of an exemplary hydraulic apparatus according to a second embodiment of the invention, said hydraulic apparatus being in engaged configuration;
• the figure 7 shows a partial diagrammatic view, in section, of the hydraulic apparatus illustrated in FIG. figure 6 in disengaged configuration;
• the figure 8 shows a partial schematic view, in section, of an alternative embodiment of the hydraulic apparatus illustrated in FIG. figure 6 ;
• the figure 9 shows a partial diagrammatic view, in section, of a sealing device of the hydraulic apparatus illustrated in FIG. figure 2 ;
• the figure 10 shows a partial diagrammatic view, in section, of a variant of the sealing device illustrated in FIG. figure 9 ;
• the figure 11 shows a partial diagrammatic view, in section, of a variant of the sealing device illustrated in FIG. figure 10 .

DETAILED DESCRIPTION

The figure 2 to 5 each have a partial sectional view of a hydraulic apparatus 10 according to a first embodiment of the invention. This figure shows an axis of rotation 11 of the hydraulic apparatus 10. The hydraulic apparatus 10 is preferably a motor. According to one variant, the hydraulic apparatus is a pump.

The hydraulic apparatus 10 comprises a shaft 12 disposed along the axis of rotation 11 and a cover 13 forming a housing element. The shaft 12 and the cover 13 are free to rotate relative to each other. The cover 13 is preferably fixed, while the shaft 12 is free to rotate about the axis of rotation 11. Preferably, the hydraulic apparatus 10 is configured to transmit only pure torque. In particular, the hydraulic apparatus 10 does not transmits no axial force, for example generated by a thrust of toothing, or radial force, for example generated by the support of a wheel.

The hydraulic apparatus 10 further comprises a dispensing assembly comprising a multilobe cam 14, a cylinder block 15, and a distributor 16.

The cam 14 is formed of a ring arranged coaxially with the axis of rotation 11 and formed in the cover 13. The ring of the cam 14 is integral with the cover 13. The cam 14 comprises on a radially inner surface, a series of equi-distributed lobes around the axis of rotation 11. Each of the lobes has a generally sinusoidal type appearance.

The cylinder block 15 is mounted on the shaft 12 and is placed inside the ring forming the cam 14. It defines a plurality of cylinders oriented radially with respect to the axis of rotation 11 and opening on a peripheral face external of the cylinder block 15 opposite the cam 14. A piston is mounted to slide radially respectively in each of the cylinders. Each piston bears on the radially inner surface of the cam 14.

The distributor 16 is mounted on the shaft 12, a first side of the cylinder block 15 along the axis of rotation 11. The distributor 16 is adapted to apply in a controlled manner a fluid under pressure successively on each of the pistons, specifically in an internal chamber of the cylinders adjacent to the pistons, so that the successive support of the pistons on the lobes of the cam 14 causes the relative rotation of the cylinder block 15 and the elements which are connected to it, in particular the shaft 12, relative to to the cam 14 and thus to the cover 13 or vice versa. To this end, there is an asymmetry between the number of lobes formed on the cam 14 and the number of associated pistons located in the cylinder block 15.

The distributor 16 is also configured to exert a thrust force P against the cylinder block 15 along the axis of rotation 11. Thus, the distributor 16 and the cylinder block 15 are in sealing contact with each other. The hydraulic apparatus 10 comprises, for example, an elastic return element, such as a tension or compression spring, to push the distributor 16 against the cylinder block 15.

In the examples illustrated in Figures 2 to 5 , the shaft 12 comprises a shoulder 17 forming an axial abutment surface 18 against which the cylinder block 15 is pushed, when the distributor 16 exerts the thrust force P against the cylinder block 15. For this, the axial abutment surface 18 (and the shoulder 17) is provided with a second side of the cylinder block opposite the first side. Thus, when the distributor 16 pushes the cylinder block 15 against the axial abutment surface 18, the thrust force P is transmitted to the shaft 12.

In the examples illustrated in Figures 2 to 5 , the dispensing assembly further comprises an actuator 19 configured to engage and disengage the cylinder block 15. For this, the actuator 19 is mounted on the shaft 12 of the second side of the cylinder block 15, between the axial abutment surface 18 and the cylinder block 15. The actuator 19 is adapted to selectively immobilize the cylinder block 15 with respect to the shaft 12. The actuator 19 is configured to immobilize the cylinder block 15 relative to the shaft 12, when it is desired that the rotation of the cylinder block 15 with respect to the cam 14 causes rotation of the shaft 12. In the examples illustrated in FIGS. figures 3 and 5 the actuator 19 is a disk pack. In a variant, the actuator 19 has a bearing surface adapted to engage the cylinder block 15. The bearing surface 20 is, for example, a radial collar arranged to frictionally engage a lateral surface of the cylinder block 15. According to a variant, a clutch device is used, that is to say a device with teeth and grooves disposed on the actuator 19 and on the cylinder block 15, to immobilize them in rotation when these teeth and grooves are engaged . According to another variant, there is a friction track on the actuator 19 and / or on the cylinder block 15. In particular, the actuator 19 may have a friction cone intended to come into contact with a cone of complementary shape arranged on the cylinder block 15 so as to engage it.

The hydraulic apparatus 10 also comprises a first mechanical bearing 21 and an assembly 22 of second mechanical bearings comprising at least one second mechanical bearing, by means of which the shaft 12 and the cover 13 are mounted to rotate relative to one another. other. To this end, the first mechanical bearing 21 and the second or second mechanical bearings 22 are mounted in radial contact with the shaft 12 on the one hand and the cover 13 on the other hand.

The assembly 22 of second mechanical bearings is configured to take up the thrust force P exerted by the distributor 16.

The first mechanical bearing 21 is a right-contact ball bearing comprising an outer cage and an inner cage between which balls are mounted. The term "right-contact ball bearing" means a ball bearing in which the resultant of the contact force of the outer cage and the inner race with the ball has only a radial component, in opposition for example to an angular contact ball bearing whose resultant will have both a radial component and an axial component. The first mechanical bearing 21 is for example a deep groove ball bearing. The right-contact ball bearing 21 is configured to take up axial forces of small amplitude with respect to the thrust force P.

In the examples illustrated in Figures 2 to 4 , the assembly 22 of second mechanical bearings is positioned on a first side of the dispensing assembly disposed in the thrust direction of the distributor 16 against the cylinder block 15. In other words, the assembly 22 of second rollers mechanical devices is arranged opposite the distributor 16 relative to the cylinder block 15. In these examples, the first mechanical bearing 21 is furthermore positioned on a second side of the distribution assembly disposed opposite the thrust direction of the distributor 16 against the cylinder block 15.

In the example shown in figure 2 , the assembly 22 of second mechanical bearings comprises a tapered roller bearing 22a having an inner race and an outer race between which conical rollers are mounted.

The tapered roller bearing 22a is arranged such that the axial resultant of the thrust force exerted by the tapered rollers on the inner race of the tapered roller bearing 22a is opposite to the thrust force P of the distributor 16 on the the block cylinder 15. In other words, the tapered roller bearing 22a is positioned so that its center of thrust C on the axis of rotation 11 is shifted towards the dispensing assembly.

In the example shown in figure 3 , the assembly 22 of second mechanical bearings comprises an angular contact ball bearing 22b having an inner race and an outer race between which balls are mounted.

The angular contact ball bearing 22b is arranged such that the axial resultant of the thrust force P exerted by the balls on the inner ring of the angular contact ball bearing 22b is in the opposite direction to the thrust force P of the distributor 16 on the cylinder block 15. In other words, the angular contact ball bearing 22b is positioned so that its center of thrust C on the axis of rotation 11 is shifted towards the distribution assembly.

In the examples illustrated in figures 2 and 3 , axially opposite sides of the inner race and the outer race of the second mechanical bearing 22a, 22b are respectively mounted in axial contact with the shaft 12 and the cover 13. For this, the inner race of the second mechanical bearing 22a, 22b is for example in axial contact with a second axial abutment surface 23 formed on the shoulder 17 of the shaft 13, opposite the first axial abutment surface 18, and a side of the outer cage of the second mechanical bearing 22a, 22b, opposite the shoulder 17, is for example in axial contact with an axial abutment surface 24 formed in the cover 13.

It will be understood that such an assembly makes it possible to ensure the recovery of the thrust force P exerted by the distributor 16 on the cylinder block 15, and which is transmitted to the shaft 12.

In the example shown in figure 4 the assembly 22 of second mechanical bearings comprises a right-contact ball bearing 22c having an outer cage and an inner cage between which balls are mounted, and a ball bearing 22d having a first cage and a second cage between which logs are mounted.

In the example shown in figure 4 , the first cage of the thrust bearing 22d is mounted in axial contact with the shaft 12, in particular with the second axial abutment surface 23 of the shaft 12. In this example, axially opposite sides of the outer race of the bearing 22c are respectively mounted in axial contact with the second cage of the thrust bearing 22d and the cover 13.

Thus, the assembly 22 of second mechanical bearings makes it possible to take up the thrust force P exerted by the distributor 16 on the cylinder block 15, and which is transmitted to the shaft 12.

Preferably, the assembly 22 of second mechanical bearings is mounted in axial clearance between the shaft 12 and the cover 13, so as to ensure the recovery of the axial forces in the hydraulic apparatus 10 and in particular to prevent the assembly 22 of second mechanical rollers does not separate.

In the examples illustrated in figures 2 and 3 the outer race of the second mechanical bearing 22a, 22b is mounted in axial contact with the cover 13 via a preload washer 28, so as to ensure that the assembly 22 of second mechanical bearings is mounted without axial play. between the shaft 12 and the cover 13. Alternatively, to overcome the preload washer 28, the hydraulic apparatus 10 can be dimensioned so that that the second mechanical bearing 22a, 22b is mounted without axial play between the shaft 12 and the cover 13.

In the example shown in figure 4 , the outer race of the right-contact ball bearing 22c is mounted in axial contact with the second cage of the thrust bearing 22d via a preload washer 29, so as to ensure the assembly without axial backlash of the assembly 22 of second mechanical bearings between the shaft 12 and the cover 13. In this example, the inner race of the right contact ball bearing 22c is not in axial contact with any part. Alternatively, to overcome the preload washer 29, the hydraulic apparatus 10 can be dimensioned so that the second mechanical bearings 22c, 22d are mounted without axial play between them and between the shaft 12 and the cover 13.

The preloading washer 28, 29 or the dimensioning of the hydraulic apparatus 10 without axial play induce a low amplitude axial preload force compared to the thrust force P. As described later, this effort is taken up by the first mechanical bearing 21.

In the examples illustrated in Figures 2 to 4 , axially opposite sides of the outer cage and the inner race of the first mechanical bearing 21 are respectively mounted in axial contact with the cover 13 and the shaft 12, so as to obtain a looping of the axial forces by the cover 13 and resume the preload force applied to the assembly 22 of second mechanical bearings. For this, the inner race of the first mechanical bearing 21 is for example mounted in axial contact with the shaft 12 by means of a first elastic ring 25 mounted in a groove on the shaft 12, between the first mechanical bearing 21 and the distribution set ( figures 3 ), and the outer race of the first mechanical bearing 21 is for example mounted in axial contact with the cover 13 by means of a second elastic ring 26 mounted in a groove on the cover 13 on one side of the first mechanical bearing Opposite the first elastic ring 25. In a variant, the first elastic ring 25 can be replaced by a shoulder having an axial abutment surface 27 ( figures 2 and 4 ). It will be understood that such an assembly allows the first mechanical bearing 21 to resume the preload force applied to the assembly 22 of second mechanical bearings.

In the example shown in figure 5 the assembly 22 of second mechanical bearings is positioned on the second side of the distribution assembly. In other words, the assembly 22 of second mechanical rollers is arranged opposite the actuator 19 relative to the cylinder block 15. In this example, the first mechanical bearing 21 is furthermore positioned on the first side of the distribution set. Such an assembly makes it possible in particular to simplify and lighten the cover 13 of the first side of the distribution assembly, the coupling (that is to say the transmission of torque) being generally performed on this side of the assembly. of distribution.

In the example shown in figure 5 , the assembly 22 of second mechanical bearings comprises a tapered roller bearing 22e having an inner race and an outer race between which conical rollers are mounted. As a variant, the assembly 22 of second mechanical bearings may comprise the second mechanical bearing or bearings 22b; 22c, 22d described in connection with the figures 3 and 4 .

The tapered roller bearing 22e is arranged such that the axial resultant of the thrust force P exerted by the tapered rollers on the inner race of the tapered roller bearing 22e is opposite to the thrust force P of the distributor. on the cylinder block 15. In other words, the tapered roller bearing 22e is positioned so that its center of thrust C on the axis of rotation 11 is shifted away from the dispensing assembly.

In the example shown in figure 5 axially opposite sides of the inner race and the outer race of the second mechanical race 22e, 22b are respectively mounted in axial contact with the shaft 12 and the cover 13. For this, the outer race of the second mechanical race 22e is example mounted in axial contact with the cover 13 via a first elastic ring 30 mounted in a groove on the cover 13, between the second mechanical bearing 22e and the distribution assembly, and the inner race of the second mechanical bearing 22e is for example mounted in axial contact with the shaft 12 via a second elastic ring 31 mounted in a groove on the shaft 12 on a side opposite to the first elastic ring 30.

It will be understood that such an assembly makes it possible to take up the thrust force P exerted by the distributor 16 on the cylinder block 15, and which is transmitted to the shaft 12.

In the example shown in figure 5 , axially opposite sides of the inner race of the first mechanical bearing 21 are both mounted in axial contact with the shaft 12, so as to obtain a looping of the forces by the shaft 12. For this, the inner race of the first mechanical bearing 21 is for example mounted in axial contact with the second axial abutment surface 23 of the shaft 12 on the one hand, and with the shaft 12 via an elastic ring 32 on the other. The outer casing of the first mechanical bearing 21 is for example mounted in axial contact with the second axial abutment surface 23 of the shaft 12 and, on the opposite side to the shoulder 17, away from the axial abutment surface 24 of the cover 13. It will be understood that by not transmitting any force from the shaft 12 to the cover 13, the first mechanical bearing 21 allows the assembly 22 of second mechanical bearings to resume the thrust force P exerted by the distributor 16 on the cylinder block 15.

As illustrated in Figures 2 to 5 the shaft 12 is hollow and configured to be mounted around a shaft, which shaft may be a differential shaft 30. The differential shaft 30 is coupled to a differential (not shown) associated with a gearbox ( not shown) at its end arranged opposite the distributor 16 with respect to the cylinder block 15. In order to seal both the differential shaft 30 and thus the differential and / or the gearbox , and the shaft 12, and within the hydraulic apparatus 10, between the shaft 12 and the cover 13, the hydraulic apparatus 10 comprises a sealing device, several variants of which are illustrated in FIGS. figures 9 , 10 and 11 .

For this, the sealing device comprises a first annular seal 35 mounted in radial contact with an outer surface of one end of the shaft 12, arranged on the side of the distributor 16 with respect to the cylinder block 15, on the one hand and the cover 13 on the other hand, and a second annular seal 37 mounted in radial contact with the inner surface of said end of the shaft 12 on the one hand and configured to be mounted in radial contact with the differential shaft 30 d 'somewhere else.

In the variant illustrated in figure 9 , the hydraulic apparatus 10 is provided with a hoop 31 comprising a first and a second concentric annular portion 32, 33, the first annular portion 32 having a diameter smaller than that of the second annular portion 33, and connected one with the other by an intermediate portion 34 extending preferably radially between said first and second annular portions 32, 33. The band 31 thus has a generally S-shaped profile.

The first annular portion 32 of the hoop 31 is mounted on the outer surface of the end of the shaft 12. The first annular seal 35 is mounted in radial contact with the first annular portion 32 of the hoop 31 on the one hand and with the cover 13 on the other hand, thereby sealing the hydraulic apparatus 10. The first annular seal 35 is thus mounted in radial contact with the shaft 12 via the first annular portion 32 of the hoop 31. The first annular portion 32 of the hoop 31 thus serves as a friction surface for the first annular seal 35. The first annular seal 35 is for example placed against the intermediate portion 34 of the hoop 31. A shoulder 36 is for example provided at the end of the shaft 12 to accommodate the first annular portion 32 of the hoop 31.

The second annular portion 33 of the hoop 31 extends from the intermediate portion 34 away from the end of the shaft 12. The second annular seal 37 is mounted in radial contact with the second annular portion 33 of the hoop 31 on the one hand and with the differential shaft 30 on the other hand, thus ensuring the seal between the differential shaft 30, and therefore the differential and / or the gearbox, and the shaft 12 of the device 10. The second annular seal 37 is thus mounted in radial contact with the shaft 12 via the second annular portion 33 of the hoop 31. The first and second annular seals 35, 37 are mounted on opposite sides of the hoop. the hoop 31. The second annular portion 33 of the hoop 31 forms a housing around the differential shaft 30 to accommodate the second annular seal 37. The differential shaft 30 has for example a flange 38 on which is mounted the second attached to Nnular 37.

In one embodiment not shown, the two annular portions 32 and 33 of the hoop 31 have the same diameter.

In a variant, the second annular portion 33 of the hoop 31 has a diameter smaller than the diameter of the first annular portion 32 of the hoop 31.

In the variant illustrated in figure 10 , the inner surface of the end of the shaft 12 is provided with a shoulder 39 forming a housing 40 between the shaft 12 and the differential shaft 30, accommodating the second annular seal 37.

The variant illustrated in figure 11 differs from the variant illustrated in figure 10 in that an annular collar 41 is further mounted on the outer surface of the end of the shaft 12 and is interposed between the first annular seal 35 and the shaft 12. The first annular seal 35 of the ferrule 31 is therefore in radial contact with the shaft 12 through the annular ring 41. The outer surface of the end of the shaft 12 is for example provided with a shoulder 36 accommodating the hoop 41. The annular ring 41 improves the friction surface between the first annular seal 35 and the shaft 12.

Moreover, to gain compactness in these two variants, the first and the second annular seals 35, 37 may be arranged at least partly around each other.

The figures 6 and 7 show a partial sectional view of a hydraulic apparatus 100 according to a second embodiment of the invention. These figures show an axis of rotation 111 of the hydraulic apparatus 100. The hydraulic apparatus 100 is preferably a motor. According to one variant, the hydraulic apparatus is a pump.

The hydraulic apparatus 100 comprises a shaft 112 disposed along the axis of rotation 111 and a cover 113 forming a housing element. The shaft 112 and the cover 113 are free to rotate relative to each other. The cover 113 is preferably fixed, while the shaft 112 is free to rotate about the axis of rotation 111. Preferably, the hydraulic apparatus 100 is configured to transmit only pure torque. In particular, the hydraulic apparatus 100 does not transmit axial force, for example generated by a thrust of toothing or radial force, for example generated by the support of a wheel.

The shaft 112 is through and disengageable. The opposite ends of the shaft 112 along the axis of rotation 111 are intended to be coupled to external shafts (not shown). To increase the torque transmission between the outer shafts and the shaft 112, the ends of the shaft 112 are provided with contact faces 137 intended to come into contact with the outer shafts, which have undergone shot blasting followed by a treatment hardening surface. The contact faces 137 are thus rough and constitute friction surfaces allowing to transmit a significant torque between the shaft 112 and the outer shafts.

In the examples illustrated in figures 6 and 7 the hydraulic apparatus 100 further comprises a seal support ring 138. The seal support ring 138 extends around the shaft 112, at one end thereof, and is in axial contact with the cover 113. The seal support ring 138 is for example maintained in axial contact with the cover 113 and fixed to said cover 113 by means of a plurality of screws 139 distributed over the entire circumference of the ring 138. A lip 140 s extends further axially from the seal support ring 138, in radial contact with the cover 113 so as to form a space between the lip 140, the ring 138 and the shaft 112, accommodating a seal and thus ensure the sealing of the hydraulic device 100. The seal support ring 138 is particularly advantageous because it is easily replaceable during the maintenance of the hydraulic device 100. Such a seal support ring 138 can be mounted to one or the other or even to the two x ends of the shaft 112.

The hydraulic apparatus 100 is for example used as a motor for motor vehicles with hydrostatic and mechanical drive. In a mechanical drive mode, the hydraulic apparatus 100 is disengaged and the shaft 112 is driven by the engine through the vehicle gearbox. In a hydrostatic drive, the hydraulic apparatus 100 is engaged and drives the shaft 112, the gearbox of the engine being in this case in neutral and the engine driving the pump providing the oil flow necessary for the operation of the engine. hydraulic apparatus 100.

The hydraulic apparatus 100 further comprises a dispensing assembly including a multilobed cam 114, a cylinder block 115, and a dispenser 116.

The cam 114 is formed of a ring arranged coaxially with the axis of rotation 111 and formed in the cover 113. The ring of the cam 114 is integral with the cover 113. The cam 114 comprises on a radially internal surface, a series of equi-distributed lobes around the axis of rotation 111. Each of the lobes has a generally sinusoidal type appearance.

The cylinder block 115 is mounted on the shaft 112 and is placed inside the ring forming the cam 114. It defines a plurality of cylinders oriented radially with respect to the axis of rotation 111 and opening on a peripheral face external cylinder block 115 opposite the cam 114. A piston is mounted radially sliding respectively in each of the cylinders. Each piston bears on the radially inner surface of the cam 114.

The distributor 116 is mounted on the shaft 112, a first side of the cylinder block 115 along the axis of rotation 111. The distributor 116 is adapted to apply in a controlled manner a fluid under pressure successively on each of the pistons, specifically in an internal chamber of the cylinders adjacent to the pistons, so that the successive support of the pistons on the lobes of the cam 114 causes the relative rotation of the cylinder block 115 and the elements which are connected to it, in particular the shaft 112, relative to to the cam 114 and thus to the cover 113 or vice versa. To this end, there is an asymmetry between the number of lobes formed on the cam 114 and the number of associated pistons located in the cylinder block 115.

The distributor 116 is also configured to exert a thrust force P against the cylinder block 115 along the axis of rotation 111. Thus, the distributor 116 and the cylinder block 115 are in sealing contact with each other. The hydraulic apparatus 100 comprises for example an elastic return element, such as a tension or compression spring, to push the distributor 116 against the cylinder block 115.

In the examples illustrated in figures 6 and 7 the hydraulic apparatus 100 is further provided with a sleeve 130 threaded onto the shaft 112. The sleeve 130 is rotatably mounted around the shaft 112. At a first end thereof, the sleeve 130 is locked in translation by a shoulder 117 formed in the shaft 112. At a second end of its ends, the sleeve 130 forms a surface axial stop 118 against which the cylinder block 115 is pushed, when the distributor 116 exerts the thrust force P against the cylinder block 115. For this, a shoulder 141 is also formed in the cylinder block 115 so as to accommodate the second end of the sleeve 130. The cylinder block 115 thus extends around the second end of the sleeve 130. Thus, when the distributor 116 pushes the cylinder block 115 against the axial abutment surface 118 of the sleeve 130, the thrust force P is transmitted to the shaft 112 via the sleeve 130 and the shoulder 117 of said shaft 112.

In the examples illustrated in figures 6 and 7 , the hydraulic apparatus 100 comprises a clutch system configured to engage the shaft 112 in an engaged configuration ( figure 6 ) and to disengage the shaft 112 in a disengaged configuration ( figure 7 ). In other words, in the engaged configuration, the hydraulic apparatus 100 rotates the shaft 112, while in the disengaged configuration, the hydraulic apparatus 100 can not drive the shaft 112 in rotation.

For this, the clutch system comprises for example a splined clutch ring 145 which, in the engaged configuration, is mounted on both the shaft 112 and the sleeve 130, so that the hydraulic apparatus 100 rotates both the shaft 112 and the sleeve 130, and which, in the disengaged configuration, is mounted only on the sleeve 130, so that the hydraulic apparatus 100 causes rotation only of the sleeve 130 and no longer that of the shaft 112, the sleeve 130 and the shaft 112 being free to rotate relative to each other. In the engaged configuration, the spline clutch ring 145 extends partly around the shaft 112, in particular the shoulder 117 of the shaft 112, and the first end of the sleeve 130. In the disengaged configuration , the splined clutch ring 145 no longer extends that around the first end of the sleeve 130. The splined clutch ring 145 is configured to move from one configuration to another by translation along the axis of rotation 111. The clutch ring With splines 145 is for example controlled in translation by a control cylinder of the clutch system. This makes it possible to couple or uncouple the hydraulic apparatus 100 from the shaft 112.

The hydraulic apparatus 100 also comprises a set 121 of first mechanical bearings comprising at least a first mechanical bearing 121a, 121b and an assembly 122 of second mechanical bearings comprising at least a second mechanical bearing 122a, 122b, 122c by means of which the shaft 112 and the cover 113 are mounted rotating relative to each other. To this end, the first mechanical bearings 121a, 121b and at least one of the second mechanical bearings 122a, 122b are mounted in radial contact with the shaft 112 on the one hand and the cover 113 on the other.

In the example shown in figure 6 , the assembly 121 of first mechanical bearings comprises two first mechanical bearings 121a, 121b disposed on either side of the distribution assembly, in particular of the cylinder block 115 and the distributor 116. In other words, one 121a of the first mechanical bearings is arranged opposite the distributor 116 relative to the cylinder block 115 and the other 121b of the first mechanical bearings is arranged opposite the cylinder block 115 relative to the distributor 116. The first mechanical bearings 121a, 121b are in direct radial contact with the shaft 112 and the cover 113.

The first mechanical bearings 121a, 121b are right contact ball bearings each comprising an outer cage and an inner race between which balls are mounted. The first mechanical bearings 121 are for example deep groove ball bearings. The right contact ball bearings 121a, 121b are configured to take axial forces of low amplitude relative to the thrust force P.

The set 122 of second mechanical bearings is configured to take up the thrust force P exerted by the distributor 116.

In the example shown in figure 6 , the set 122 of second mechanical bearings comprises a tapered roller bearing 122a having an inner race and an outer race between which conical rollers are mounted. The second mechanical bearing 122a is positioned on a first side of the dispensing assembly disposed in the thrust direction of the distributor 116 against the cylinder block 115. In other words, the assembly 122 of second mechanical rolls is arranged at the opposite of the distributor 116 relative to the cylinder block 115.

The tapered roller bearing 122a is arranged such that the axial resultant of the thrust force exerted by the tapered rollers on the inner race of the tapered roller bearing 122a is in the opposite direction to the thrust force P of the distributor 116. on the cylinder block 115. In other words, the tapered roller bearing 122a is positioned so that its center of thrust C on the axis of rotation 111 is shifted towards the dispensing assembly.

The tapered roller bearing 122a is in radial contact with the shaft 112 via the sleeve 130 on the one hand and with the cover 113 on the other hand.

Axially opposite sides of the inner race of the second mechanical bearing 122a are respectively mounted in axial contact with the shaft 112, via the sleeve 130, and the cylinder block 115, while one side of the outer race of the second mechanical bearing 122a , opposed to the cylinder block 115 along the axis of rotation 111, is mounted in axial contact with the cover 113. A shoulder 131 is for example formed in the sleeve 130 to form an abutment surface against which the inner race of the second bearing mechanical 122a is mounted in axial contact.

It will be understood that such an assembly makes it possible to ensure the recovery of the thrust force P exerted by the distributor 116 on the cylinder block 115, and which is transmitted to the shaft 112.

Preferably, the tapered roller bearing 122a is mounted without axial clearance between the shaft 112 and the cover 113, so as to ensure the recovery of the axial forces in the hydraulic apparatus 100 and in particular to prevent the tapered roller bearing 122a from dissociates.

For this, the hydraulic apparatus 100 is for example dimensioned so that the tapered roller bearing 122a is mounted without axial play between the latter and the shaft 112 / the cover 113. Alternatively, an elastic ring 142 can be inserted in a groove in the sleeve 130, opposite the inner cage side of the tapered roller bearing in contact with the cylinder block 115, and a precharge washer 143 is positioned between the elastic ring 142 and said inner cage side , so as to ensure the mounting of the tapered roller bearing 122a without axial play. A shoulder 144 may further be provided in the cylinder block 115 to accommodate the elastic ring 142 and the preload washer 143.

In the example shown in figure 6 , axially opposite sides of the inner race of the first mechanical bearing 121a located on the first side of the distribution assembly, are both mounted in axial contact with the shaft 112. Similarly, axially opposite sides of the outer race of the first mechanical bearing 121a located on the first side of the dispensing assembly, are both mounted in axial contact with the cover 113.

In addition, axially opposite sides of the inner race of the first mechanical bearing 121b located on a second side of the dispensing assembly, opposite the first side, are both mounted in axial contact with the shaft 112, while none of the axially opposite sides of the outer cage is in axial contact with the cover 113 or the shaft 112. One of the axially opposite sides of the inner race of the first mechanical bearing 121b is for example mounted in axial contact with the shaft 112 by means of an elastic ring 132 inserted into a groove in the shaft 112.

According to a variant of the hydraulic apparatus 100 illustrated in FIG. figure 6 , the hydraulic apparatus 100 is configured to operate with two displacement cylinders. For this, the hydraulic apparatus 100 comprises a cylinder of displacement selection, allowing the passage of a displacement to the other. This drawer can be a symmetrical drawer, that is to say that the hydraulic apparatus 100 has no preferential direction (same behavior in forward and reverse of the vehicle when the hydraulic apparatus 100 is a motor).

In the example shown in figure 8 , the set 122 of second mechanical bearings comprises a needle bearing 122b having an outer cage and an inner cage between which needles are mounted, and a cylindrical roller stop 122c having a first cage and a second cage between which cylindrical rollers are mounted.

The inner race of the needle bearing 122b is in radial contact with the shaft 112 via the sleeve 130, while its outer shaft is in direct radial contact with the cover 113.

Axially opposite sides of the inner race of the needle bearing 122b are respectively mounted in axial contact with the shaft 112, via the sleeve 130 and for example the shoulder 131 formed in said sleeve 130, and the cover 113, for example by via an elastic ring 133 inserted into a groove in the cover 113. Axially opposite sides of the outer race of the needle bearing 122b are both mounted in axial contact with the cover 113, for example via a shoulder 134 forming an abutment surface formed in the cover 113 on the one hand, and on the other hand via the elastic ring 133 of the cover 113.

Thus, the needle bearing 122b aligns the sleeve 130 and the cover 113.

The first cage of the cylindrical roller thrust 122c is mounted in axial contact with the cover 113 and the second cage of the cylindrical roller thrust 122c is mounted in axial contact with the cylinder block 115.

Radially opposite sides of the first cage and the second cage, respectively corresponding to the radially outer and radially inner sides of the first cage and the second cage, of the cylindrical roller stopper 122c are respectively mounted in radial contact with the cover 113. and the cylinder block 115. For this, a groove 135 is for example formed in the cover 113 to receive the first cage of the cylindrical roller thrust 122c. In addition, a shoulder 136 is for example formed in the cylinder block 115 to receive the second cage of the cylindrical roller thrust 122c.

Thus, the cylindrical roller thrust 122c makes it possible to absorb the thrust force P exerted by the distributor 116 on the cylinder block 115, and which is transmitted to the shaft 112.

Preferably, the cylindrical roller stop 122c is mounted without axial clearance between the cover 113 and the cylinder block 115, so as to ensure the recovery of the axial forces in the hydraulic apparatus 100 and in particular to prevent the cylindrical roller thrust 122c from dissociates. For this, the hydraulic apparatus 100 is dimensioned so that the cylindrical roller stopper 122c is mounted without axial play between the latter and the cover 113 / the cylinder block 115.

Furthermore, in order to minimize the bulk of the hydraulic apparatus 100, the cylindrical roller stopper 122c has an inner diameter greater than the inner diameter of the needle bearing 122b so that the two bearings 122b, 122c are arranged concentrically, the cylindrical roller thrust 122c extending for example at least in part around the needle bearing 122b.

Hydraulic devices 10, 100 illustrated in FIGS. Figures 2 to 11 have the advantage of ensuring a recovery of the thrust force P of the distributor 16 against the cylinder block 15, 115, while allowing to reduce the preload force applied to the mechanical bearings 21 and 22; 121 and 122 and thus reduce their drag, and thus increase their life. Furthermore, the axial dimension of such hydraulic devices 10, 100 can be reduced, since the ball bearings have a reduced axial dimension compared to the axial dimension of a tapered roller bearing. Finally, ball bearings have the advantage of being less expensive and lighter than tapered roller bearings.

Claims (15)

1. Hydraulic device (10, 100) with radial pistons comprising:

   - a shaft (12, 112) arranged along an axis (11, 111);

   - a cover (13, 113) forming a casing element, the cover and the shaft being free to rotate with respect to one another;

   - a distribution assembly comprising:

   - a multi-lobe cam (14, 114);

   - a cylinder block (15, 115) radially facing the cam (14, 114), said cylinder block comprising a plurality of cylinders (17, 117) wherein are arranged pistons guided so as to slide radially in the respective cylinders of the cylinder block and bearing on the lobes of the cam;

   - a distributor (16, 116) configured to exert a thrust force (P) against the cylinder block (15, 115) along the axis (11, 111) of the shaft so as to successively apply a fluid under pressure to said pistons;

   - a first mechanical bearing (21; 121a, 121b) mounted in radial contact between the cover (13, 113) and the shaft (12, 112), and

   - a set (22, 122) of second mechanical bearings comprising at least one second mechanical bearing (22a; 22b; 22c, 22d; 22e; 122a; 122b, 122c) mounted in radial contact between the cover (13, 113) and the shaft (12, 112), said set (22, 122) of second mechanical bearings being configured to take up the thrust force (P) exerted by the distributor (16, 116);

   wherein the first mechanical bearing is a radial contact ball bearing and characterized in that the first mechanical bearing (21) and the set (22) of second mechanical bearings are arranged on either side of the distribution assembly.
2. Hydraulic device (10, 100) according to claim 1, wherein the second mechanical bearing (22a; 22b; 122a) is a conical roller bearing or an oblique contact ball bearing.
3. Hydraulic device (10, 100) according to claim 2, wherein the second mechanical bearing (22a, 22b; 122a) comprises an external cage and an internal cage between which rolling elements are mounted, and wherein the axially opposite sides of the internal cage and of the external cage are respectively mounted in axial contact with the shaft (12, 112) and the cover (13, 113), so as to take up the thrust force (P).
4. Hydraulic device (100) according to claim 2 or claim 3, comprising a sleeve (130) mounted in rotation around the shaft (112) and by means of which the second mechanical bearing (122a) is mounted in radial contact and in axial contact with the shaft (112).
5. Hydraulic device (10) according to claim 1, wherein the set (22) of second mechanical bearings comprises a radial contact ball bearing (22c) and a ball thrust bearing (22d).
6. Hydraulic device (10) according to claim 5, wherein the ball thrust bearing (22d) comprises a first cage and a second between which balls are mounted, wherein the radial contact ball bearing (22c) of the set (22) comprises an internal cage and an external cage between which are mounted the balls, and wherein the first cage is mounted in axial contact with the shaft (12), and axially opposite sides of the external cage of the radial contact ball bearing (22c) of the set (22) are respectively mounted in axial contact with the second cage of the ball thrust bearing (22d) and the cover (13) so as to take up the thrust force (P).
7. Hydraulic device (100) according to claim 1, wherein the set (122) of second mechanical bearings comprises a needle bearing (122b) and a cylindrical roller thrust bearing (122c).
8. Hydraulic device (100) according to claim 7, wherein the cylindrical roller thrust bearing comprises a first cage and a second cage between which are mounted the cylindrical rollers, the first cage of the cylindrical roller thrust bearing (122c) being mounted in axial contact with the cover (113) and the second cage of the cylindrical roller thrust bearing (122c) being mounted in axial contact with the cylinder block (115), radially opposite sides of the first cage and of the second cage of the cylindrical roller thrust bearing (122c) being respectively mounted in radial contact with the cover (113) and the cylinder block (115).
9. Hydraulic device (100) according to claim 7 or to claim 8, wherein the needle bearing (122b) comprises an internal cage and an external cage between which the needles are mounted, axially opposite sides of the internal cage of the needle bearing (122b) being respectively mounted in axial contact with the shaft (112) and the cover (113), and axially opposite corners for the external cage of the needle bearing (122b) being mounted in axial contact with the cover (113).
10. Hydraulic device (100) according to one of claims 7 to 9, comprising a sleeve (130) mounted in rotation around the shaft (112) and by means of which the needle bearing (122b) is mounted in radial contact with the shaft (112).
11. Hydraulic device (10, 100) according to one of claims 1 to 10, wherein the set (22, 122) of second mechanical bearings is mounted without axial clearance between the shaft (12, 122) and the cover (13, 113), and wherein, for example, in combination with claim 4, the external cage of the second mechanical bearing (22a, 22b) is mounted in axial contact with the cover (13) by means of a pre-loading spacer (28), so as to ensure assembly without axial clearance of the set (22) of second mechanical bearings between the shaft (12) and the cover (13).
12. Hydraulic device (10) according to claim 5 and claim 11, wherein the external cage of the radial contact ball bearing (22c) of the set (22) is mounted in axial contact with the second cage of the ball thrust bearing (22d) by means of a pre-loading spacer (29) so as to ensure assembly without axial clearance of the set (22) of second mechanical bearings between the shaft (12) and the cover (13).
13. Hydraulic device (10, 100) according to one of claims 1 to 12, wherein the set (22, 122) of second mechanical bearings is positioned on a first side of the distribution assembly arranged in the thrust direction of the distributor (16, 116) against the cylinder block (15, 115) and wherein, for example, the first mechanical bearing (21, 121a) is positioned on a second side of the distribution assembly arranged opposite to the thrust direction of the distributor (16, 116) against the cylinder block (15, 115), and wherein, for example, wherein the first mechanical bearing (21) comprises an internal cage and an external cage between which are mounted the balls, and wherein the axially opposite sides of the external cage and of the internal cage are respectively mounted in axial contact with the cover (13) and the shaft (12) so as to obtain closure of the axial forces by the cover (13).
14. Hydraulic device (10) according to one of claims 1 to 12, wherein the set (22) of second mechanical bearings is positioned on the second side of the distribution assembly arranged opposite to the thrust direction of the distributor (16) against the cylinder block (15) and wherein, for example, the first mechanical bearing (21) is positioned on the first side of the distribution assembly arranged in the thrust direction of the distributor (16) against the cylinder block (15) and wherein, for example, the first mechanical bearing (21) comprises an internal cage and an external cage between which are mounted the balls, and wherein the axially opposite sides of the internal cage are both mounted in axial contact with the shaft (12) so as to ensure closure of the forces by the shaft (12).
15. Hydraulic device (10) according to any one of claims 1 to 14, wherein the shaft (12) is hollow and configured to be mounted around a shaft, particularly a differential shaft (30), said hydraulic device (10) comprising a first ring seal (35) mounted in radial contact with an external surface of an end of the shaft (12) on the one hand and the cover (13) on the other hand and a second ring seal (37) mounted in radial contact with an internal surface of said end of the shaft (12) on the one hand and configured to be mounted in radial contact with the shaft (30) on the other hand.

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