Hydrostatic rotating machine with optimized brake

Abstract

Hydrostatic rotation machine comprising: – an internal element (1) and an external element (2) coaxial and mounted to rotate relative to each other about an axis of rotation (R), one of these elements being a rotor and the other of these elements being a stator; – a counter-brake disc (31) which is mounted on a distribution base (4), which extends radially around the distribution base (4), and which is coupled in rotation with the external element (2); – a passive braking piston (36) adapted to activate a brake (21) under the effect of an elastic element (43), and mounted axially movable relative to the counter-brake disc (31); – a hydraulic release chamber (50) arranged between the counter-brake disc (31) and the passive braking piston (36). Figure for the abstract: Fig.1

Description

Title of the invention: Hydrostatic rotation machine with optimized brake Technical field

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

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

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

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

[0005] Such a hydrostatic machine can be equipped with a passive or dynamic brake allowing the rotor to be braked or even immobilized. PRIOR ART

[0006] Patent application EP3233553 describes a hydrostatic rotation machine comprising: - a rotor and a stator; - pistons moving in cylinders and cooperating with a cam path in a coordinated manner with the rotation of the rotor relative to the stator; - a distribution base attached to the stator; - a hydraulic distributor mounted on the distribution base and adapted to selectively connect the cylinders to a hydraulic circuit; - a brake adapted to oppose the rotational movement of the rotor relative to the stator.

[0007] Although this hydrostatic machine has advantages in several areas, it can still be improved with regard to the optimization of its braking and its compactness. Statement of the invention

[0008] The invention aims to improve the hydrostatic rotation machines of the prior art.

[0009] To this end, the invention relates to a hydrostatic rotation machine comprising: - an internal element and an external element coaxial and mounted to rotate one by relative to each other about an axis of rotation, one of these elements being a rotor and the other of these elements being a stator; - pistons moving in cylinders and cooperating with a cam path in a coordinated manner with the rotation of the rotor relative to the stator; - a distribution base coupled in rotation to the external element; - a hydraulic distributor mounted on the distribution base and adapted to selectively connect the cylinders to a hydraulic circuit; - a brake adapted to oppose the rotational movement of the rotor relative to the stator.

[0010] This hydrostatic rotation machine further comprises: - a counter-brake disc which is mounted on the distribution base, which extends radially around the distribution base, and which is rotationally coupled with the external element; - a passive braking piston adapted to activate said brake under the effect of an elastic element, and mounted axially movable relative to the counter-brake disc; - a hydraulic release chamber arranged between the counter-brake disc and the passive braking piston.

[0011] Such a hydrostatic machine benefits from a reduction in its weight, its size, and its cost.

[0012] Thanks to the counter-brake disc, the invention makes it possible to ensure the braking functions with few additional parts and with a simplification of these parts. The invention allows in particular a significant gain in compactness in length of the hydrostatic machine.

[0013] The invention also makes it possible to have a brake equipped with large diameter discs, which promotes braking performance as well as reducing noise during braking. The use of large diameter brake discs does not impact the size of the hydrostatic machine.

[0014] The invention allows for optimized braking thanks to parts which, in addition to being few in number, can essentially be machined on a lathe, which further guarantees a reduction in costs.

[0015] Passive braking here refers to braking that is activated in the absence of hydraulic fluid pressure, and which is deactivated by a positive action of pressurizing a hydraulic chamber. This passive braking allows for example the realization of parking braking, and is imperative in most hydrostatic machines. The invention makes it possible to optimize this passive braking and makes it possible to add to it, optionally, dynamic braking which here refers to braking that is activated by a positive action of pressurizing a hydraulic clamping chamber, and which activates a dynamic braking piston. Dynamic braking is advantageous, even obligatory, in particular on hydrostatic engines powering vehicles which exceed a certain speed.

[0016] The invention allows the addition of dynamic braking without any modification of the other elements. The invention allows a standardization of the production of hydrostatic machines, with a basic model that includes all the parts necessary for the basic functions, with a location for a dynamic braking piston that may or may not be added depending on the model to be produced. Such standardization optimizes costs. This possibility is also advantageous for designers of machines using such hydrostatic machines, the design of the machine simply having to take into account the physical characteristics of implementing a standard hydrostatic machine, whether or not it is equipped with dynamic braking.

[0017] The hydrostatic rotation machine according to the invention may include the following additional characteristics, alone or in combination:

[0018] - the counter-brake disc is mounted so as to move in axial translation on the disc base tribute;

[0019] - the machine includes a stop for stopping the axial translation of the counter-disc brake towards the brake;

[0020] - the machine comprises an annular feed chamber arranged between the distribution base and the counter-brake disc, this annular supply chamber being connected on the one hand to the hydraulic release chamber and on the other hand to a base conduit projecting from the distribution base;

[0021] - the annular feed chamber is delimited by two annular seals arranged between the distribution base and the brake disc;

[0022] - the annular feed chamber is defined by two recesses of complementary diameters, respectively of the distribution base and the counter-brake disc;

[0023] - the counter-brake disc comprises: a central ring extending axially and mounted on the distribution base; and a radial portion extending radially from this central ring;

[0024] - the central ring of the counter-brake disc has a cylindrical bearing surface external, and the passive braking piston is a part of revolution comprising a central orifice, the passive braking piston being mounted on the distribution base by mounting the internal contour of said central orifice on said cylindrical surface;

[0025] - the radial portion of the counter-brake disc has an oblique section extending radially outwards and towards the passive braking piston;

[0026] - the passive braking piston comprises a radial portion and a cylindrical portion axial includes a support end adapted to activate the brake;

[0027] - the axial cylindrical portion of the passive braking piston has a cy- internal lindicator mounted on the brake disc;

[0028] - the hydraulic release chamber is closed by two annular seals arranged each between the counter brake disc and the passive brake piston;

[0029] - the counter-brake disc has stops angularly distributed on its circumference conference, facing the brake, and arranged opposite a shoulder of the external element;

[0030] - the counter-brake disc is angularly indexed with the hydraulic distributor and with the external element by pawns;

[0031] - the machine comprises a braking ring which comprises: an annular portion braking adapted to activate the brake; and a bearing surface on which the passive braking piston is adapted to press; said bearing surface being radially outside relative to the annular braking portion;

[0032] - the braking ring has through holes for the passage of said stops;

[0033] - the counter-brake disc has a drainage duct passing axially through it from one end to the other;

[0034] - the distribution base has a drain outlet, and the hydraulic distributor has a threaded retaining bore, and the drain conduit, the drain outlet, and the threaded retaining bore being adapted to align along an axis parallel to the axis of rotation;

[0035] - the machine comprises a dynamic braking piston comprising an end support which is substantially axially aligned with a support end of the passive braking piston;

[0036] - the dynamic braking piston comprises an axial cylindrical portion fitted between the passive braking piston and the external element;

[0037] - the dynamic braking piston has a sliding base inserted in a dynamic braking chamber formed in the external element;

[0038] - the counter-brake disc comprises: an axial stop adapted to rest axially on a complementary bearing surface provided on the passive braking piston; and at least one threaded bore adapted to align with a through hole made in the distribution base;

[0039] - the passive braking piston comprises an axial stop adapted to rest on a additional range of the dynamic braking piston. PRESENTATION OF FIGURES

[0040] Other characteristics and advantages of the invention will emerge from the non-limiting description which follows, with reference to the appended drawings in which:

[0041] - [Fig.l] is a sectional view of a hydrostatic machine according to the invention;

[0042] - [Fig.2] illustrates the braking ring of the hydrostatic machine of [Fig.l];

[0043] - [Fig.3] illustrates in perspective the counter-brake disc 31 of the hydro machine static of [Fig.l];

[0044] - [Fig.4] is a view similar to [Fig.l] for another angular position of the rotor relative to stator;

[0045] - [Fig.5] is a detail view of insert V of [Fig.4];

[0046] - [Fig.6] is a detail view illustrating a variant of the hydrostatic machine;

[0047] - [Fig.7] is a perspective view of the hydrostatic machine according to the invention;

[0048] - [Fig.8] and [Fig.9] are detailed sectional views of the hydrostatic machine.

[0049] Elements similar and common to the various embodiments bear the same reference numbers in the figures. DETAILED DESCRIPTION

[0050] [Fig.l] illustrates a hydrostatic rotation machine according to the invention, seen in section along a plane extending along its axis of rotation R.

[0051] This hydrostatic machine is either a hydraulic motor driving an element in rotation from a pressurized hydraulic fluid, or a hydraulic pump adapted to put a pressurized hydraulic fluid from the rotation of an element.

[0052] The hydrostatic rotation machine comprises an internal element 1 and an external element 2 which are mounted to rotate relative to each other around the axis of rotation R by bearings 14, 15.

[0053] In the present illustrative example, the hydrostatic machine is a hydraulic motor and the internal element 1 is integral with a drive element which here consists of a splined shaft 3.

[0054] Among the internal element 1 and the external element 2, one of these elements is a rotor while the other of these elements is a stator. In the present example, the external element 2 is a stator and is connected to a frame such as a fixed structure or one mounted on a vehicle, while the internal element 1 is a rotor and the splined shaft 3 is connected for example to a wheel or a pinion.

[0055] The external element 2 comprises a housing 5, which here has a tubular shape, with a first cover 6 which hermetically closes one of the openings (on the right of [Fig.l]) of this tubular housing 5, and a second cover 7 which hermetically closes the opposite opening (on the left of [Fig.l]).

[0056] The external element 2 is furthermore integral with a cam path 8. In the present example, the hydrostatic machine has radial pistons, with a cam path 8 forming a circumferential path internal to the wall of the housing 5. This path is formed of hollows and bumps, constituting a cyclic path with a succession of increasing and decreasing radii synchronized with the entry and exit movement. 12 pistons.

[0057] This cam path 8 may for example be machined directly on an internal face of the external element 2, for example machined directly on an internal face of the housing 5. However, as illustrated in the figures, the present example preferably implements a cam path 8 carried by a cam ring 9 like that described in the patent application WO2020008145. This cam ring 9 is inserted into the housing 5 of the external element 2, on an internal surface and is stopped in rotation by any means.

[0058] The internal element 1 comprises a cylinder block 10 which is provided with cylinders 11 in which pistons 12 are mounted, which are here radially movable.

[0059] In a known manner, the cylinders 11 are here radial cylinders and extend over the entire circumference of the cylinder block 10, angularly distributed in a regular manner around the axis of rotation R, and the pistons 12 each comprise, on their end facing the cam path 8, a roller 13 (seen in section in the various drawings) allowing rolling without sliding on the cam path 8.

[0060] The cam paths for hydrostatic machines, the cooperation with the radial pistons, and the synchronization methods by selectively connecting the cylinders with the hydraulic fluid circuit, are also known and will not be described in more detail here.

[0061] The internal element 1 and the external element 2 are mounted rotating relative to each other thanks, in this example, to a first bearing 14 and a second bearing 15 directly mounted between the internal element 1 and the external element 2. In addition to the cam ring 9, the tubular housing 5 carries these bearings 14, 15. The example of the drawings illustrates two possible assemblies of the bearings 14, 15 in the housing 5: a direct assembly of the bearing with its external ring in contact with the housing 5 (this is the case of the first bearing 14); and an assembly of the bearing in the housing with an intermediate support ring (this is the case of the second bearing 15), and in the present example this support ring is part of the second cover 7.

[0062] The cylinder block 10 comprises two collars 16, 17 arranged on either side of the cylinders 11, with a bearing 14, 15 mounted between each collar 16, 17 and the external element 2, the internal ring of each bearing 14, 15 being directly mounted on the corresponding collar 16, 17.

[0063] The hydrostatic machine further comprises means for distributing and synchronizing the hydraulic fluid. These means comprise a hydraulic distributor 18 and a distribution base 4.

[0064] The distribution base 4 comprises a fluid inlet 19 and a fluid outlet 20 which are connected in a conventional manner to the high and low pressure portions. pressure of a hydraulic circuit. The hydrostatic machine also has a drain described later.

[0065] The distribution base 4 is coupled in rotation to the external element 2. In the present example, the distribution base 4 is integral with the external element 2, and is more precisely integral with the first cover 6. The distribution base 4 is centered on the axis of rotation R.

[0066] The hydraulic distributor 18 is mounted on the distribution base 4, being axially movable relative to the latter, the two parts being coupled in rotation, by any means such as pins allowing axial sliding.

[0067] In this example, the hydraulic distributor 18 comprises a central chamber 22 and a peripheral chamber 23, each connected to the fluid inlet 19 or the fluid outlet 20. [Fig. 1] illustrates the connection of the chambers 22, 23 to the fluid inlets / outlets 19, 20 according to the present example.

[0068] Seals allow the hermetic partitioning of the chambers 22, 23, while allowing the axial movement of the hydraulic distributor 18 on the distribution base 4.

[0069] In a known manner, the hydraulic distributor 18 is biased towards the cylinder block 10, so that the hydraulic distributor 18 is adapted to selectively connect the cylinders 11 to a hydraulic circuit, thanks to a synchronization junction forming a rotating coupling between the rotor and the stator. The distribution base 4 has in fact an increasing diameter producing a differential axial thrust on the hydraulic distributor 18 which presses the faces of the hydraulic distributor and the cylinder block which form this synchronization junction against each other, with a force proportional to the hydraulic fluid pressure.

[0070] In a known manner, the hydraulic fluid is selectively distributed by conduits provided in the cylinder block and the hydraulic distributor 18, by placing these conduits in communication at the rotating junction. The cylinders 11 are thus selectively placed in fluid communication with the high pressure or low pressure part of a hydraulic circuit, in a cyclic manner, in coordination with the path of the rollers 13 of the pistons 12 on the cam path 8.

[0071] The hydrostatic machine further comprises a brake 21 adapted to oppose the rotation of the rotor relative to the stator, and to stop this relative movement. A set of braking means is associated with this brake 21, and comprises in particular a braking ring 29, a counter-brake disc 31, a passive braking piston 36, and an optional dynamic braking piston 37.

[0072] The brake 21 is produced in a conventional manner by the mutual clamping of a multitude of friction surfaces, with an alternation of friction surfaces linked in rotation to the rotor and friction surfaces linked in rotation to the stator.

[0073] The brake 21 comprises in this example, arranged alternately: - a series of internal discs 24 coupled in rotation with the internal element 1; - a series of external discs 25 coupled in rotation to the external element 2.

[0074] The discs 24, 25, although coupled in rotation to the internal element 1 or to the external element 2, are axially movable.

[0075] In a known manner, the internal discs 24 and / or the external discs 25 can be provided with conventional friction linings of braking elements.

[0076] During rotation of the rotor relative to the stator, the tightening of this set of discs 24, 25 causes the rotor to brake relative to the stator.

[0077] In the present example, and in a particularly advantageous manner, the brake 21 is arranged around the hydraulic distributor 18, as described in the document EP3233553. In this example, one of the collars 16 of the cylinder block 10 comprises a collar 26 which has a general shape of a cylinder coaxial with the axis of rotation R, and which surrounds the hydraulic distributor 18. The collar 26 is itself surrounded by the brake 21. The axial length of the brake 21 is close to the axial length of the hydraulic distributor 18.

[0078] The collar 26, as a part belonging to the internal element 1, carries on its radially external face means of coupling in rotation, such as grooves, with the internal discs 24 (the latter carrying the teeth complementary to these grooves). The internal discs 24 are thus coupled in rotation with the internal element 1, while being axially sliding relative to the latter.

[0079] The external element 2, at the level of the housing 5 in this example, comprises a tubular braking portion 27 extending coaxially to the axis of rotation R and surrounding the collar 26. This tubular braking portion 27 comprises, on its radially internal face, grooves and the external discs 25 comprise complementary teeth on their external periphery. The external discs 25 are thus coupled in rotation to the external element 2 while being axially sliding relative to the latter.

[0080] The tubular braking portion 27 comprises a support rib 28 which contributes to the rigidity of the housing 5, making it possible to reduce its size, particularly in terms of thickness, and which also fulfills a stop function for the brake 21.

[0081] The hydrostatic machine further comprises a braking ring 29 which is adapted to activate the brake 21, by pressure on the stack of discs 24, 25.

[0082] The braking ring 29 is shown alone, in perspective, in [Fig. 2]. This braking ring 29 comprises on one side a support surface 79 and on the other side an annular braking portion 30 axially projecting in the direction of the brake 21. The support surface 79 has a larger diameter than the annular braking portion 30. In other words, the support surface 79 is located radially to the outside relative to the annular braking portion 29.

[0083] The braking ring 29 is axially movable and makes it possible to compress the discs 24, 25 of the brake 21 between the support rib 28 and the annular braking portion 30, in response to a force exerted on the support surface 79.

[0084] The hydrostatic machine further comprises a counter-brake disc 31 which is mounted on the distribution base 4 and which extends radially around the distribution base 4.

[0085] The counter-brake disc 31 is also shown alone, in perspective in [Fig.3]

[0086] The counter-brake disc 31 comprises in this example: - a central ring 32 extending in the axial direction, with a bore centered on the axis of rotation R, and mounted on the distribution base 4; - a radial portion 33 formed by a portion of solid disc extending between the central ring 32 and the periphery of the counter-brake disc 31; - four stops 34 projecting axially from the periphery of the counter-brake disc 31, and distributed angularly over its circumference, one of these stops 34A comprising an angular indexing groove 35.

[0087] The braking means further comprise a passive braking piston 36 making it possible to activate the brake 21, in the absence of hydraulic fluid pressure. This passive braking is for example implemented for a parking brake.

[0088] The passive braking piston 36 is a part of revolution, having the same profile over its entire circumference, this profile being seen in section in [Fig.l].

[0089] The passive braking piston 36 is mounted on the central ring 32 of the counter-brake disc 31. The central ring 32 has for this purpose, on its radially external face, a cylindrical bearing surface 77 which allows the mounting and the guiding in axial translation of the passive braking piston 36. The passive braking piston 36 has a central orifice, centered on the axis of rotation R, the internal contour of which is adjusted in a sliding manner on the cylindrical bearing surface 77 of the counter-brake disc 31.

[0090] The passive braking piston 36 is mounted on the central ring 32 by means of an annular seal 38 guaranteeing the seal, at this level, between the counter-brake disc 31 and the passive braking piston 36.

[0091] The passive braking piston 36 comprises a radial portion 39, in the form of a solid disc portion extending from the central orifice which allows the passive braking piston 36 to be mounted on the counter-brake disc 31. The passive braking piston 36 further comprises an axial cylindrical portion 40 extending coaxially with the axis of rotation R, from the periphery of the radial portion 39. The axial cylindrical portion 40 has a bearing end 41 adapted to activate the braking. The axial cylindrical portion 40 comprises an internal cylindrical bearing surface 78 (mounted on the counter- brake 31). Another annular seal 42 ensures the seal between the internal cylindrical bearing surface 78 and the circumferential edge of the counter-brake disc 31, so as to guarantee the seal, at this level, between the counter-brake disc 31 and the passive braking piston 36.

[0092] The passive braking piston 36 is thus axially movable relative to the counter-brake disc 31 thanks to the sliding permitted by the two seals 38, 42 at the level of the two coaxial cylindrical bearing surfaces 77, 78 formed at the level of the central ring 32 of the counter-brake disc 31 and the axial cylindrical portion 40 of the dynamic braking piston 37.

[0093] The passive braking piston 36, given its function, is urged to activate the brake 21 by an elastic element 43. In the present example, this elastic element 43 is an elastic conical washer, of the “Belleville” type. The elastic element 43 urges the passive braking piston 36 towards the brake 21, and towards the counter-brake disc 31.

[0094] In the schematic views of the figures, the elastic element 43 is shown in its rest position, in the absence of stress, which is illustrated schematically by an interpenetration of the elastic element 43 and the passive braking piston 36. In reality, during the assembly of these elements, the elastic element 43 bears on the passive braking piston 36 and deforms elastically by exerting a force tending to push the passive braking piston 36 away from the first cover 6. The force thus created between these two elements allows, at rest, in the absence of any other stress, to press the bearing end 41 of the axial cylindrical portion 40 of the passive braking piston 36 against the bearing surface 79 of the braking ring 29, which allows activation of the brake 21 and immobilization of the rotor relative to the stator.

[0095] The elastic element 43 is dimensioned so that the force applied in this situation exerts the braking force required, taking into account the entire system, to immobilize the rotor relative to the stator.

[0096] In the present example, the elastic element 43 is arranged between the passive braking piston 36 and the first cover 6 of the external element 2.

[0097] [Fig.4] is a view similar to [Fig.1], for another angular position of the rotor relative to the stator. This [Fig.4] makes visible an angular indexing orifice 45 (also visible in [Fig.3]) made in the counter-brake disc 31, at the level of its central ring 32. A pin 46 takes place in this orifice 45 and is also inserted into an angular indexing orifice 47 of the hydraulic distributor 18. The angular indexing of the distributor 18 relative to the counter-brake disc 31 is thus ensured.

[0098] In addition, the external element 2 (and more precisely the housing 5 in this example) also includes an angular indexing orifice 48 also receiving a pin 49, the latter being furthermore adjusted in the angular indexing groove 35 of the stop 34A of the counter-brake disc 31. The angular indexing of the counter-brake disc 31 relative to the external element 2 is thus ensured.

[0099] The counter-brake disc 31 is thus a single part which allows, directly by its sole intermediary, an angular indexing of the hydraulic distributor 18 with respect to the external element 2. The counter-brake disc 31 is a part of revolution which can be machined on a lathe, with a single part grip allowing the production with significant mechanical precision of its two angular indexing elements 35, 45. A precise angular indexing, which is essential for the function of the hydraulic distributor 18, with a very low dispersion, is thus guaranteed at a lower cost.

[0100] With reference to [Fig.3], the braking ring 29 comprises through orifices 76 for the passage of said stops 34. One of these orifices 76A is in the form of a notch also allowing the passage of the pin 49.

[0101] Furthermore, with reference to Figures 1 and 4, a hydraulic release chamber 50 is arranged between the counter-brake disc 31 and the passive braking piston 36. In the present example, the counter-brake disc 31 and the passive braking piston 36 define between them the hydraulic release chamber 50 thanks to the constitution of each of these elements in a radial component 33, 39 and an axial component 32, 40 mounted head to tail, and thanks to the annular seals 38, 42 allowing relative axial translation in a sealed manner, along the two coaxial cylindrical bearing surfaces 77, 78.

[0102] Thus, when the hydraulic release chamber 50 is pressurized by the hydraulic fluid, a separation force is created between the counter-brake disc 31 and the passive braking piston 36. When designing the hydrostatic machine, the volume of the hydraulic release chamber 50 can be adjusted by the difference in diameter between the two annular seals 38, 42, and can thus be adapted to the desired force for the release of the passive braking, without harming the gain in compactness in length of the hydrostatic machine.

[0103] The arrangement of the counter-brake disc 31 has the advantage of allowing the use of a central ring 32 of a relatively large internal diameter, which in turn makes it possible to provide a distribution base 4 of a sufficiently large diameter to accommodate fluid inlet 19 and fluid outlet 20 conduits inducing low pressure losses, without harming the braking performance and while remaining very compact, particularly in length. In the present example (see [Fig.l]), these fluid inlet 19 and fluid outlet 20 conduits advantageously have a large diameter and paths close to rectilinear paths, without bends.

[0104] To supply the hydraulic release chamber 50 with hydraulic fluid, the hydrostatic machine comprises an annular supply chamber 51 between the counter-brake disc 31 and the distribution base 4. A base conduit 52 (which opens outside, onto the distribution base 4, for its connection to the hydraulic circuit) and a transmission conduit 53 (which also opens into the hydraulic release chamber 50) both open into the annular supply chamber 51.

[0105] [Fig.5] is a detailed view of insert V of [Fig.4] and shows the mounting of the counter-brake disc 31 on the distribution base 4.

[0106] Two annular seals 54 are arranged between the counter-brake disc 31 and the distribution base 4, defining between them a sealed space in the gap between these two parts. The annular supply chamber 51 is arranged between these two annular seals 54.

[0107] In this example, the annular supply chamber 51 is formed by a first recess 56 in the diameter of the central ring 32 of the counter-brake disc 31, and a second recess 57 in the diameter of the distribution base 4. These two recesses 56, 57 are complementary and axially separated so that the annular supply chamber 51 is defined by these two recesses 56, 57 and made watertight by the annular seals 54.

[0108] This configuration allows the creation of the annular supply chamber 54 while maintaining optimal axial guidance of the translation of the counter-brake disc 31 on the distribution base 4. In addition, during the manufacture of the hydrostatic machine, thanks to the change in diameter of the parts induced by the recesses 56, 57, the counter-brake disc 31 can be mounted by sliding on the distribution base 4, so that the first annular seal 54 does not encounter any cavity other than its own bearing surface, and the second annular seal 54 likewise. The two annular seals 54 are thus slid on their respective bearing surface without encountering any sharp edge, which is a critical point on this type of assembly.

[0109] The counter-brake disc 31 is free to slide axially by axial translation of the central ring 32 on the hydraulic distributor 4, thanks to the sliding of the annular seals 54 according to a stroke which is framed: on one side by a stop formed by the contact of the central ring 32 with the distribution base 4 or the first cover 6; and on the other side by a stop 55 which is, in this example, constituted by an elastic ring. The stop 55 makes it possible to form an end-of-stroke stop for the translation of the counter-brake disc 31 in the direction of the brake 31.

[0110] The constitution of the annular supply chamber 51 allows, while remaining intact, this axial sliding.

[0111] The passive braking function is implemented in the following manner.

[0112] Without activation of the hydraulic circuit at the level of the hydraulic chamber of release 50, the elastic element 43 urges the passive braking piston 36 towards the brake 21 so that its support end 41 pushes back the braking ring 29 which itself compresses the set of discs 24, 25 of the brake 21. Given the calibration of the elastic element 43 taking into account the nature of the discs 24, 25, this operation achieves the braking and immobilization of the rotor relative to the stator.

[0113] When the hydrostatic machine is put into operation, in order to obtain rotation of the rotor relative to the stator, the hydraulic release chamber 50 is pressurized by the hydraulic fluid supplied by the base conduit 52 (connected to the hydraulic circuit), the annular supply chamber 51, and the transmission conduit 53.

[0114] This pressurization of the hydraulic release chamber 50 causes the counter-brake disc 31 to come into abutment against its stop 55, and the axial backward movement of the passive braking piston 36, which then moves away from the counter-brake disc 31, compressing the elastic element 43. This causes a release of the stress exerted on the braking ring 29 and therefore a release of the brake 21.

[0115] As soon as the pressure is no longer maintained in the hydraulic release chamber 50, the passive braking piston 36 returns to its brake application position 21 under the effect of the elastic element 43.

[0116] In normal operation, or in the event of overpressure in the hydraulic release chamber 50, the counter-brake disc 31 deforms and the four stops 34 come to bear against a shoulder 58 of the external element 2 (in the present example, the shoulder 58 is directly made in the housing 5). For this purpose, when the system is at rest, the dimensioning of the counter-brake disc 31 is such that the stops 34 have a reduced axial clearance with the shoulder 58, for example a clearance of less than 1 mm.

[0117] A large diameter counter-brake disc 31 can thus be advantageously used, without impacting its function.

[0118] The braking ring 29 makes it possible to receive the pressure of the passive braking piston 36 on a radially very external diameter (its bearing surface 79), close to the housing 5, but to retransmit this pressure by a smaller diameter at the level of its annular braking portion 30. This action on a smaller diameter corresponding to the brake 21, from a larger diameter, allows an arrangement of the passive braking piston 36 with an axial cylindrical portion 40 of small thickness and significant axial length, but of large diameter, which makes it a rigid part and forms a large diameter surface for sealing at the level of the annular seal 42.

[0119] The sectional view of [Fig.4] also shows a drainage duct 59 made in the brake disc 31, at the level of its central ring 32, and passing axially through it from one side to the other. The drainage duct 59 is also visible in [Fig.3].

[0120] The drainage conduit 59 allows fluid communication on either side of the counter-brake disc 31, so that no element partitions this hydraulic fluid, and that a single drain outlet 60, on the distribution base 4, is necessary for the function of draining the hydraulic fluid, despite the presence of the counter-brake disc 31.

[0121] The hydrostatic machine further comprises in this example a dynamic braking piston 37 allowing an active braking function under the effect of a positive command on a brake actuator, from an operator or a device.

[0122] The dynamic braking function is optional here and the hydrostatic machine is of almost identical construction, whether this dynamic braking function is implemented or not. [Fig.6] illustrates for this purpose a variant without the dynamic braking function, in a partial sectional view, limited to these elements.

[0123] When this dynamic braking function is implemented, as in Figures 1 and 4, the hydrostatic machine comprises a dynamic braking piston 37 which has a sliding base 61 and an axial cylindrical portion 62.

[0124] The sliding base 61 is provided with seals and is inserted into a dynamic braking chamber 66 which is made in the external element 2. In this example, the dynamic braking chamber 66 is produced in a particularly advantageous manner, by a simple tubular projection 63 of the first cover 6, and by taking advantage of the adjacent internal surface of the housing 5, at the junction of the first cover 6 and the housing 5.

[0125] The axial cylindrical portion 62 of the dynamic braking piston 37 is fitted (by a sliding fit) between the axial cylindrical portion 40 of the passive braking piston 36 and the external element 2 (the housing 5 in this example).

[0126] The axial cylindrical portion 62 of the dynamic braking piston 37 comprises a bearing end 64 which is substantially axially aligned with the bearing end 41 of the axial cylindrical portion 40 of the passive braking piston 36. These two bearing ends 41, 64 are thus both able to exert pressure on the bearing surface 79 of the braking ring 29, which is opposite each other.

[0127] [Fig.7] is a perspective view illustrating the hydrostatic machine as seen from the outside, on the side of the first cover 6. [Fig.7] shows a dynamic braking duct 65 which is made in the external element 2 (in the cover 6 for this example). This dynamic braking duct 65 is extremely short (it corresponds to the thickness of the first cover 6) and opens directly into the dynamic braking chamber 66.

[0128] To implement the dynamic braking function during operation of the hydrostatic machine, the dynamic braking chamber 66 is therefore put into pressure by the hydraulic fluid supplied by the dynamic braking conduit 65. The dynamic braking piston 37 is then translated axially in the direction of the brake 21, so that its support end 64 acts on the braking ring 29 and activates the brake 21.

[0129] It is specified that the dynamic braking piston 37 advantageously does not require any other guidance for its translation than its adjustment between the passive braking piston 36 and the external element 2. A very compact adjustment is thus obtained for one, or even two braking functions. In addition, the hydrostatic machine remains as compact, whether or not the optional dynamic braking function is implemented.

[0130] The counter-brake disc 31 also has an additional brake release function, for maintenance operations or in the event of failure. [Fig.8] is a partial sectional view illustrating a portion of the internal element 1 and of the external element 2, around the distribution base 4, according to another angular position of the rotor relative to the stator, making visible threaded bores 67 which are made in the central ring 32 of the counter-brake disc 31.

[0131] In the present example, these threaded bores 67 are 4 in number, angularly distributed around the circumference of the brake disc 31.

[0132] These threaded bores 67 correspond to through holes 68 made in the distribution base. In the present example, these through holes 68 are threaded bores of larger diameter than the threaded bores 67 and which are, in normal operation, sealed by screws 69. The screws 69 and one of the threaded bores 68 are also visible in [Fig.7].

[0133] According to this brake release function, in the event of a breakdown or for maintenance operations, it is possible to release all the braking functions, by positioning the rotor relative to the stator (by a relative rotation of a maximum of a quarter turn) until the threaded bores 67, 68 are aligned, by extracting the screws 69, then by inserting maintenance screws with the diameter of the thread of the threaded bores 67 of the counter-brake disc 31 so that the tightening of these maintenance screws causes the counter-brake disc 31 to be pulled towards the first cover 6, along a stroke sufficient to release both the passive braking piston 36 and the dynamic braking piston 37 if the latter is present.

[0134] [Fig.9] is a detail view illustrating in particular the arrangement of the elements of stop enabling this brake release function. The counterbrake disc 31 comprises an axial stop 70 adapted to push a complementary bearing surface 71 onto the passive braking piston 36, and the passive braking piston 36 also comprises an axial stop 72 adapted to push a complementary bearing surface 73 onto the dynamic braking piston 37.

[0135] The axial stop 70 of the counter-brake disc 31 is produced by means of an oblique section 74 of the radial portion 33, which extends radially outwards and in the direction of the passive braking piston 36. This oblique section 74 also makes it possible to improve the compactness of the hydrostatic machine.

[0136] Furthermore, with reference to [Fig.4], the hydraulic distributor 4 may comprise a threaded angular indexing bore 75, accessible through the drainage conduit 59 and the drain outlet 60, and allowing, during the manufacture of the hydrostatic machine, the insertion of a threaded pin allowing the angular indexing and the holding of the hydraulic distributor 18 on the distribution base 4, in order to hold these elements together during assembly.

[0137] Alternative embodiments may be envisaged. In particular, the entire part of the hydraulic distribution, and of the cooperation of the pistons 12 with the cam path 8, may be different from that given here as an example. Furthermore, the rotational coupling of the counter-brake disc 31 with the external element 2 may be achieved by other alternatives, for example by a tight mounting of the counter-brake disc 31 on the distribution base 4.

Claims

Claims

1. Hydrostatic rotation machine comprising: - an internal element (1) and an external element (2) coaxial and mounted to rotate relative to each other about an axis of rotation (R), one of these elements being a rotor and the other of these elements being a stator; - pistons (12) movable in cylinders (11) and cooperating with a cam path (8) in a manner coordinated with the rotation of the rotor relative to the stator; - a distribution base (4) coupled in rotation to the external element (2); - a hydraulic distributor (18) mounted on the distribution base (4) and adapted to selectively connect the cylinders (11) to a hydraulic circuit; - a brake (21) adapted to oppose the rotational movement of the rotor relative to the stator;this hydrostatic rotation machine being characterized in that it comprises: - a counter-brake disc (31) which is mounted on the distribution base (4), which extends radially around the distribution base (4), and which is coupled in rotation with the external element (2); - a passive braking piston (36) adapted to activate said brake (21) under the effect of an elastic element (43), and mounted axially movable relative to the counter-brake disc (31); - a hydraulic release chamber (50) arranged between the counter-brake disc (31) and the passive braking piston (36).;

2. Hydrostatic rotation machine according to claim 1, characterized in that the counter-brake disc (31) is mounted to move in axial translation on the distribution base (4).

3. Hydrostatic rotation machine according to claim 2, characterized in that it comprises a stop (55) for stopping the axial translation of the counter-brake disc (31) in the direction of the brake (21).

4. Hydrostatic rotation machine according to one of the preceding claims, characterized in that it comprises an annular supply chamber (51) arranged between the distribution base (4) and the counter-brake disc (31), this annular supply chamber (51) being connected on the one hand to the hydraulic release chamber (50) and on the other hand to a base conduit (52) projecting from the distribution base tribute (4).

5. Hydrostatic rotation machine according to claim 4, characterized in that the annular supply chamber (51) is delimited by two annular seals (54) arranged between the distribution base (4) and the counter-brake disc (31).

6. Hydrostatic rotation machine according to one of claims 4 or 5, characterized in that the annular supply chamber (51) is defined by two complementary diameter recesses, respectively of the distribution base (4) and of the counter-brake disc (31).

7. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the counter-brake disc (31) comprises: a central ring (32) extending axially and mounted on the distribution base (4); and a radial portion (33) extending radially from this central ring (32).

8. Hydrostatic rotation machine according to claim 7, characterized in that the central ring (32) of the counter-brake disc (31) has an external cylindrical bearing surface (77), and in that the passive braking piston (36) is a part of revolution having a central orifice, the passive braking piston (36) being mounted on the distribution base (4) by mounting the internal contour of said central orifice on said cylindrical bearing surface (77).

9. Hydrostatic rotation machine according to one of claims 7 or 8, characterized in that the radial portion (33) of the counter-brake disc (31) has an oblique section (74) extending radially outwards and in the direction of the passive braking piston (36).

10. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the passive braking piston (36) comprises a radial portion (39) and an axial cylindrical portion (40) comprising a support end (41) adapted to activate the brake (21).

11. Hydrostatic rotation machine according to claim 10, characterized in that the axial cylindrical portion (40) of the passive braking piston (36) comprises an internal cylindrical bearing surface (78) mounted on the counter-brake disc (31).

12. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the hydraulic release chamber (50) is closed by two annular seals (38, 42) each arranged between the counter-brake disc (31) and the passive braking piston (36).

13. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the counter-brake disc (31) comprises stops (34) angularly distributed over its circumference, facing the brake (21), and arranged opposite a shoulder (58) of the external element (2).

14. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the counter-brake disc (31) is angularly indexed with the hydraulic distributor (18) and with the external element (2) by pins (46, 49).

15. Hydrostatic rotation machine according to one of the preceding claims, characterized in that it comprises a braking ring (29) which comprises: an annular braking portion (30) adapted to activate the brake (21); and a bearing surface (79) on which the passive braking piston (36) is adapted to press; said bearing surface (79) being radially outside relative to the annular braking portion (30).

16. Hydrostatic rotation machine according to claim 15 when it depends on claim 13, characterized in that the braking ring (29) comprises through orifices (76) for the passage of said stops (34).

17. Hydrostatic rotation machine according to one of the preceding claims, characterized in that the counter-brake disc (31) comprises a drainage conduit (59) passing axially through it from one side to the other.

18. Hydrostatic rotation machine according to claim 17, characterized in that the distribution base comprises a drain outlet (60), and the hydraulic distributor (18) comprises a threaded holding bore (75), and in that the drainage conduit (59), the drain outlet (60), and the threaded holding bore (75) are adapted to align along an axis parallel to the axis of rotation (R).

19. Hydrostatic rotation machine according to one of the preceding claims, characterized in that it comprises a dynamic braking piston (37) comprising a support end (64) which is substantially axially aligned with a support end (41) of the passive braking piston (36).

20. Hydrostatic rotation machine according to claim 19, characterized in that the dynamic braking piston (37) comprises an axial cylindrical portion (62) fitted between the passive braking piston (36) and the external element (2).

21. Hydrostatic rotation machine according to claim 20, characterized in that the dynamic braking piston (37) comprises a sliding base (61) inserted in a dynamic braking chamber (66) formed in the external element (2).

22. Hydrostatic rotation machine according to one of claims 2 to 21, characterized in that the counter-brake disc (31) comprises: an axial stop (70) adapted to bear axially on a complementary bearing surface (71) provided on the passive braking piston (36); and at least one threaded bore (67) adapted to align with a through hole (68) made in the distribution base (4).

23. Hydrostatic rotation machine according to claim 22 when it depends on claim 19, characterized in that the passive braking piston (36) comprises an axial stop (72) adapted to rest on a complementary bearing surface (73) of the dynamic braking piston (37).

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