Hydrostatic rotary machine with optimized brake

Abstract

Hydrostatic rotary machine comprising:-an inner element (1) and an outer element (2) coaxial and mounted with the ability 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 brake reaction disc (31) mounted on the distribution hub (4), which extends radially around the distribution hub (4) and which is rotationally coupled to the outer element (2); -a passive brake piston (36) designed to activate the brake (21) under the action of an elastic element (43) and mounted with axial mobility relative to said brake reaction disc (31); -a hydraulic brake release chamber (50) positioned between the brake reaction disc (31) and the passive brake piston (36).

Description

Technical Field

[0001] The present invention relates to the fields of mechanics and hydraulics, and more particularly, to a hydrostatic rotary machine.

[0002] A hydrostatic rotary machine is a rotary machine including a stator coupled to a rotor, the rotor typically being connected to a rotary drive element such as a wheel, a pinion, or some form of gearing.

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

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

[0005] Such a hydrostatic machine can be equipped with a passive or dynamic brake for braking or even immobilizing the rotor. Background Art

[0006] Patent application EP3233553 describes a hydrostatic rotary machine including:

[0007] - a rotor and a stator;

[0008] - pistons that are capable of moving within cylinders and that cooperate with cam surfaces in a manner coordinated with the rotation of the rotor relative to the stator;

[0009] - a distribution hub firmly attached to the stator;

[0010] - a hydraulic distributor mounted on the distribution hub and designed to selectively connect the hydraulic cylinders to a hydraulic circuit;

[0011] - a brake designed to resist the rotational movement of the rotor relative to the stator.

[0012] Although such a hydrostatic machine offers advantages at many levels, there is still room for improvement in optimizing its braking and compactness. Summary of the Invention

[0013] The object of the present invention is to improve the rotary hydrostatic machines of the prior art

[0014] To this end, the object of the present invention is a rotary hydrostatic machine including:

[0015] - an internal element and an external element that are coaxial and mounted so as to be capable of rotating relative to each other about a rotation axis, one of these elements being the rotor and the other of these elements being the stator;

[0016] - A piston that is capable of moving within a cylinder and that cooperates with a cam surface in a manner coordinated with the rotation of the rotor relative to the stator;

[0017] - A distribution hub rotatably coupled to an external element;

[0018] - A hydraulic distributor mounted on the distribution hub and designed to selectively connect the cylinder to a hydraulic circuit;

[0019] - A brake designed to resist the rotational movement of the rotor relative to the stator.

[0020] This rotary hydrostatic machine further includes:

[0021] - A brake reaction disk mounted on the distribution hub, which extends radially around the distribution hub and which is rotatably coupled to an external element;

[0022] - A passive brake piston designed to activate the brake under the action of an elastic element and which is mounted to have axial mobility relative to the brake reaction disk;

[0023] - A hydraulic brake release chamber positioned between the brake reaction disk and the passive brake piston.

[0024] This hydrostatic machine benefits from a reduction in its weight, its volume and its cost.

[0025] Thanks to the brake reaction disk, the present invention makes it possible to carry out the braking function with very few additional parts and simplifies such parts. The present invention particularly allows a significant improvement in the longitudinal compactness of the hydrostatic machine.

[0026] The present invention is also capable of providing a brake equipped with a large-diameter disk, which contributes to good braking performance and to a reduction in braking noise. Using a large-diameter brake disk does not affect the volume of the hydrostatic machine.

[0027] The present invention provides optimized braking, which is due to the fact that, in addition to being few in number, the parts can essentially be machined on a lathe, thereby further ensuring a cost reduction.

[0028] Passive braking here refers to a brake that is activated in the absence of hydraulic fluid pressure and that is deactivated by an active action of pressurizing a hydraulic chamber. This passive braking allows, for example, the provision of a parking brake and is necessary in most hydrostatic machines. The present invention is capable of optimizing this passive braking and, optionally, increasing its dynamic braking, which here refers to a brake that is activated by an active action of pressurizing a hydraulic braking application chamber and that activates a dynamic brake piston. Dynamic braking is advantageous or even mandatory, particularly for a hydrostatic motor that provides dynamic braking for a vehicle moving at a speed above a certain value.

[0029] The present invention allows for additional dynamic braking without any modification to other components. The present invention allows for the standardization of the production of hydrostatic machines, with a basic model including all the components required for the basic functions, and a space for the dynamic braking piston that can be increased or not depending on the model to be produced. This standardization optimizes costs. This possibility is also advantageous for the designers of equipment using such hydrostatic machines, whose design must simply take into account the physical characteristics of the operation of the standard hydrostatic machine, regardless of whether it is provided with dynamic braking.

[0030] The rotary hydrostatic machine according to the present invention may include, individually or in combination, the following additional features:

[0031] - The brake reaction disc is mounted with axial translatability on the distribution hub;

[0032] - The machine includes end stops that stop the axial translation of the brake reaction disc in the direction of the brake;

[0033] - The machine includes an annular supply chamber positioned between the distribution hub and the brake reaction disc, which is connected on the one hand to the hydraulic brake release chamber and on the other hand to a hub conduit extending from the distribution hub;

[0034] - The annular supply chamber is delimited by two annular seals positioned between the distribution hub and the brake reaction disc;

[0035] - The annular supply chamber is respectively defined by two diametrically complementary interruptions of the distribution hub and the brake reaction disc;

[0036] - The brake reaction disc includes: a central ring extending axially and mounted on the distribution hub; and radial portions extending radially from the central ring;

[0037] - The central ring of the brake reaction disc includes an external cylindrical support surface, and the passive braking piston is a rotationally symmetric component including a central orifice, and the passive braking piston is mounted on the distribution hub by mounting the inner periphery of the central orifice on the cylindrical support surface;

[0038] - The radial portions of the brake reaction disc have inclined segments extending radially outward and towards the passive braking piston;

[0039] - The passive braking piston includes a radial portion and an axial cylindrical portion, and the axial cylindrical portion includes a pressing end designed to activate the brake;

[0040] - The axial cylindrical portion of the passive braking piston includes an inner cylindrical support surface mounted on the brake reaction disc;

[0041] - The hydraulic braking release chamber is closed by two annular seals, each seal being positioned between the brake reaction disc and the passive brake piston;

[0042] - The brake reaction disc includes extrusion stops, which are angularly distributed on its circumference, face the brake and are positioned opposite the shoulders of the external element;

[0043] - The brake reaction disc is angularly indexed with the hydraulic distributor and the external element by means of pins;

[0044] - The machine includes a brake ring, which includes: an annular braking portion designed to activate the brake; and an extrusion surface on which the passive brake piston is designed to press; the extrusion surface is located radially outside the annular braking portion;

[0045] - The brake ring includes a through-hole through which the extrusion stops can pass;

[0046] - The brake reaction disc includes a discharge conduit axially passing through it;

[0047] - The distribution hub includes a discharge outlet, and the hydraulic distributor includes a threaded retaining hole, and the discharge conduit, the discharge outlet and the threaded retaining hole are designed to be aligned along an axis parallel to the rotation axis;

[0048] - The machine includes a dynamic brake piston, which includes an extrusion end substantially axially aligned with the extrusion end of the passive brake piston;

[0049] - The dynamic brake piston includes an axially cylindrical portion fitted between the passive brake piston and the external element;

[0050] - The dynamic brake piston includes a sliding hub inserted into a dynamic brake chamber formed in the external element;

[0051] - The brake reaction disc includes: an axial extrusion stop designed to axially press on a complementary support surface provided on the passive brake piston; and at least one threaded hole designed to be aligned with a through-hole made in the distribution hub;

[0052] - The passive brake piston includes an axial extrusion stop designed to press against a complementary support surface of the dynamic brake piston. Description of the Drawings

[0053] With reference to the accompanying drawings, further features and advantages of the present invention will become apparent from the following non-limiting description, in which:

[0054] - Figure 1 is a cross-sectional view of a hydrostatic machine according to the present invention;

[0055] - Figure 2 illustrates the brake ring of a hydrostatic machine; Figure 1

[0056] - Figure 3 is Figure 1 a perspective view of the brake reaction disk 31 of the hydrostatic machine of

[0057] - Figure 4 is a view similar to Figure 1

[0058] - Figure 5 is Figure 4 a detailed view of detail V of

[0059] - Figure 6 is a detailed view illustrating a variant of the hydrostatic machine;

[0060] - Figure 7 is a perspective view of the hydrostatic machine according to the present invention;

[0061] - Figure 8 and Figure 9 are detailed cross-sectional views of the hydrostatic machine.

[0062] Referring to the accompanying drawings, elements that are similar and common to the various embodiments have the same reference numerals. Detailed Description

[0063] Figure 1 Illustrated is the rotary hydrostatic machine as viewed in cross-section in a plane extending along the axis of rotation R of the rotary hydrostatic machine according to the present invention.

[0064] Such a hydrostatic machine is either a hydraulic motor that rotationally drives elements by using pressurized hydraulic fluid or a hydraulic pump that is designed to pressurize hydraulic fluid by using the rotation of elements.

[0065] The rotary hydrostatic machine includes an internal element 1 and an external element 2, which are mounted by means of rolling bearings 14, 15 with the ability to rotate relative to each other about the axis of rotation R.

[0066] In this illustrative example, the hydrostatic machine is a hydraulic motor, and the internal element 1 is firmly attached to a drive element, which here includes a splined shaft 3.

[0067] Of the internal element 1 and the external element 2, one of these elements is a rotor and the other of these elements is a stator. In this example, the external element 2 is the stator and is connected to a support, which is stationary or a vehicle-mounted structure carried on a vehicle, while the internal element 1 is the rotor and the splined shaft 3 is connected to, for example, a wheel or a pinion.

[0068] The external element 2 includes a housing 5 which is tubular in shape here, having a first cover 6 and a second cover 7, the first cover 6 sealingly closing one of the openings of the tubular housing 5 (on the Figure 1 right side in Figure 1 ), and the second cover 7 sealingly closing the opposite opening (on the

[0069] left side in

[0070] ). The external element 2 is additionally firmly attached to the cam surface 8. In the present example, the hydrostatic machine has a radial piston which has a cam surface 8 which forms a circumferential path inside the wall of the housing 5. The path consists of depressions and protrusions, thus constituting a cyclic path with a succession of increasing and decreasing radii, which is synchronized with the reciprocating movement of the piston 12.

[0071] The internal element 1 itself includes a cylinder block 10 equipped with cylinders 11, in which pistons 12 are mounted, in this instance radially movable pistons.

[0072] In a known manner, the cylinders 11 here are radial cylinders which extend over the entire circumference of the cylinder block 10 and are evenly angularly distributed around the rotary cylinder axis R, and each of the pistons 12 includes a roller 13 at its end facing the cam surface 8 which is capable of rolling without slipping on the cam surface 8 (observed in the cross-section of the respective figures).

[0073] The cam surface for a hydrostatic machine, the cooperation with the radial piston, and the method of achieving synchronization by selectively placing the cylinders in communication with the hydraulic fluid circuit are known elsewhere and will not be described in detail here.

[0074] In this example, the inner element 1 and the outer element 2 are mounted so as to be capable of rotating relative to each other by means of a first rolling bearing 14 and a second rolling bearing 15 directly mounted between the inner element 1 and the outer element 2. In addition to supporting the cam ring 9, the tubular housing 5 also supports these rolling bearings 14, 15. The example in the drawings illustrates two possible ways of mounting the rolling bearings 14, 15 in the housing 5: direct mounting in which the rolling bearing contacts the housing 5 through its outer ring (as in the case of the first rolling bearing 14); and mounting the rolling bearing in the housing by means of an intermediate clamping ring (as in the case of the second rolling bearing 15), and in this example, the clamping ring forms part of the second cover 7.

[0075] The cylinder block 10 includes two flanges 16, 17 positioned on each side of the cylinder 11, where the rolling bearings 14, 15 are mounted between each flange 16, 17 and the outer element 2, and the inner ring of each rolling bearing 14, 15 is directly mounted on the corresponding flange 16, 17.

[0076] The hydrostatic machine further includes means for distributing and synchronizing the hydraulic fluid. These means include a hydraulic distributor 18 and a distribution hub 4.

[0077] The distribution hub 4 includes a fluid inlet 19 and a fluid outlet 20, which are connected in a conventional manner to the high-pressure and low-pressure parts of the hydraulic circuit. The hydrostatic machine also includes discharge means described later.

[0078] The distribution hub 4 is rotationally coupled to the outer element 2. In this example, the distribution hub 4 is firmly attached to the outer element 2, and more specifically, firmly attached to the first cover 6. The distribution hub 4 is centered on the axis of rotation R.

[0079] The hydraulic distributor 18 is mounted on the distribution hub 4 and has axial mobility relative to the distribution hub 4, and the two components are rotationally coupled by any means allowing axial sliding (such as pins).

[0080] In this example, the hydraulic distributor 18 includes a central chamber 22 and a peripheral chamber 23, each of which is connected to the fluid inlet 19 or the fluid outlet 20. Figure 1 The connection of the chambers 22, 23 to the fluid inlets / outlets 19, 20 according to this example is illustrated.

[0081] Seals seal off the chambers 22, 23 from each other while allowing axial movement of the hydraulic distributor 18 on the distribution hub 4.

[0082] In a known manner, the hydraulic distributor 18 is pushed towards the cylinder block 10 such that the hydraulic distributor 18 is designed to selectively connect the cylinder 11 to the hydraulic circuit by means of a synchronous joint that forms a rotary connection between the rotor and the stator. In fact, the distribution hub 4 has an increased diameter, generating a differential axial thrust on the hydraulic distributor 18, which presses firmly against each other the surfaces of the hydraulic distributor and the cylinder block that form this synchronous joint with a force proportional to the hydraulic fluid pressure.

[0083] In a known manner, the hydraulic fluid is selectively distributed by ducts provided in the cylinder block and in the hydraulic distributor 18, since these ducts become connected at the rotary joint. Thus, the cylinder 11 is selectively fluidly connected to the high-pressure or low-pressure part of the hydraulic circuit according to a cycle coordinated with the path of the rollers 13 of the piston 12 along the cam surface 8.

[0084] The hydrostatic machine further includes a brake 21, which is designed to resist 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 particularly includes a brake ring 29, a brake reaction disk 31, a passive brake piston 36 and optionally a dynamic brake piston 37.

[0085] The brake 21 operates in a conventional manner by clamping together a plurality of friction surfaces, with an alternation of friction surfaces rotatably connected to the rotor and friction surfaces rotatably connected to the stator.

[0086] In this example, the brake 21 includes, arranged alternately:

[0087] - a series of inner disks 24, which are rotatably coupled to the internal element 1;

[0088] - a series of outer disks 25, which are rotatably coupled to the external element 2;

[0089] Although the disks 24, 25 are rotatably coupled to the internal element 1 or the external element 2, they are axially movable.

[0090] In a known manner, the inner disks 24 and / or the outer disks 25 can be fitted with conventional brake element friction linings.

[0091] When the rotor rotates relative to the stator, the clamping together of this set of disks 24, 25 causes the rotor to be braked relative to the stator.

[0092] In this example, and particularly advantageously, the brake 21 is positioned around the hydraulic distributor 18, as described in document EP3233553. In this example, a collar 26 is provided on a flange 16 of the cylinder block 10, the collar 26 having a general cylinder shape coaxial with the axis of rotation R and surrounding the hydraulic distributor 18. The collar 26 itself is surrounded by the brake 21, the axial length of the brake 21 being similar to the axial length of the hydraulic distributor 18.

[0093] As a part belonging to the internal element 1, the collar 26 supports a rotary coupling means, such as splines, on its radially outer surface for connection to the inner disc 24 (the support teeth of the inner disc complementary to these splines). Thus, the inner disc 24 is rotationally coupled to the internal element 1 while having the ability to slide axially relative thereto.

[0094] In this example, at the housing 5, the external element 2 includes a tubular braking part 27 which extends coaxially with respect to the axis of rotation R and surrounds the collar 26. The tubular braking part 27 has splines on its radially inner face, and the outer disc 25 has complementary teeth on its outer periphery. Thus, the outer disc 25 is rotationally coupled to the external element 2 while having the ability to slide axially relative thereto.

[0095] The tubular braking part 27 includes an extrusion rib 28 which contributes to the stiffness of the housing 5, allows its dimensions, in particular its thickness, to be reduced, and also acts as an end stop for the brake 21.

[0096] The hydrostatic machine further includes a brake ring 29 which is designed to activate the brake 21 by squeezing on the stack of discs 24, 25.

[0097] In Figure 2 the brake ring 29 is depicted separately in perspective. The brake ring 29 includes a squeezing surface 79 on one side and an annular braking part 30 which projects axially towards the brake 21 on the other side. The squeezing surface 79 has a diameter greater than that of the annular braking part 30. In other words, the squeezing surface 79 is located radially outside with respect to the annular braking part 29.

[0098] The brake ring 29 is axially movable and allows the discs 24, 25 of the brake 21 to be compressed between the extrusion rib 28 and the annular braking part 30 in response to a force applied to the squeezing surface 79.

[0099] The hydrostatic machine further includes a brake reaction disc 31 which is mounted on the distribution hub 4 and extends radially around the distribution hub 4.

[0100] In Figure 3 the brake reaction disc 31 is also depicted separately in perspective.

[0101] The reaction disk 31 in this example includes:

[0102] - A central ring 32, extending in the axial direction, having a hole centered on the rotation axis R, and being mounted on the distribution hub 4;

[0103] - A radial part 33, which is formed by a solid disk part extending between the central ring 32 and the periphery of the reaction disk 31;

[0104] - Four extrusion stops 34, which axially project from the periphery of the reaction disk 31 and are angularly distributed on its circumference, and one of these extrusion stops 34A includes an angular indexing groove 35.

[0105] The braking device further includes a passive braking piston 36, which can activate the brake 21 without hydraulic fluid pressure. Such passive braking is used, for example, for parking brakes.

[0106] The passive braking piston 36 is a component with rotational symmetry, and the passive braking piston has the same outer shape over its entire circumference, and this outer shape is visible in the Figure 1 cross-section.

[0107] The passive braking piston 36 is mounted on the central ring 32 of the reaction disk 31. For this purpose, the central ring 32 has a cylindrical support surface 77 on its radial outer surface, and the passive braking piston 36 can be mounted on this support surface and guided in an axially translatable manner. The passive braking piston 36 has a central orifice centered on the rotation axis R, and the inner contour of this central orifice mates as a sliding fit with the cylindrical support surface 77 of the reaction disk 31.

[0108] The passive braking piston 36 is mounted on the central ring 32 via an annular seal 38, and this annular seal 38 provides a seal between the reaction disk 31 and the passive braking piston 36 in this area.

[0109] The passive braking piston 36 includes a radial part 39, which is in the form of a solid disk part extending from the central orifice, and this central orifice allows the passive braking piston 36 to be mounted on the reaction disk 31. The passive braking piston 36 further includes an axial cylindrical part 40, which extends coaxially from the periphery of the radial part 39 with respect to the rotation axis R. The axial cylindrical part 40 has an extrusion end 41 designed to activate the brake. The axial cylindrical part 40 includes an inner cylindrical support surface 78 (mounted on the reaction disk 31). Another annular seal 42 provides a seal between the inner cylindrical support surface 78 and the circular edge of the reaction disk 31, so as to provide a seal between the reaction disk 31 and the passive braking piston 36 in this area.

[0110] Thus, by virtue of the sliding allowed by the two seals 38, 42 at the two coaxial cylindrical bearing surfaces 77, 78, the passive braking piston 36 can move axially relative to the brake reaction disk 31, and these two coaxial cylindrical bearing surfaces 77, 78 are formed at the central ring 32 of the brake reaction disk 31 and at the axial cylindrical portion 40 of the dynamic braking piston 37.

[0111] Taking into account the function of the passive braking piston 36, the passive braking piston 36 is pushed by an elastic element 43 to activate the brake 21. In the present example, this elastic element 43 is a conical spring washer of the "Belleville" spring washer type. The elastic element 43 pushes the passive braking piston 36 towards the brake 21 and towards the brake reaction disk 31.

[0112] In the schematic view of the drawing, the elastic element 43 is depicted in its rest position without being pushed, which is schematically indicated by the mutual penetration between the elastic element 43 and the passive braking piston 36. In real life, when these elements are installed, the elastic element 43 will bear against the passive braking piston 36 and elastically deform, thereby exerting a force tending to push the passive braking piston 36 backward from the first cover 6. Therefore, the force generated between these two elements means that, at rest and without any other pushing influence, the pressing end 41 of the axial cylindrical portion 40 of the passive braking piston 36 will be pressed against the pressing surface 79 of the brake ring 29, thereby activating the brake 21 and fixing the rotor relative to the stator.

[0113] The dimensions of the elastic element 43 are such that the force applied in this case exerts the required braking force to fix the rotor relative to the stator, considering the system as a whole.

[0114] In the present example, the elastic element 43 is positioned between the passive braking piston 36 and the first cover 6 of the external element 2.

[0115] Figure 4 is a view similar to that of another angular position of the rotor relative to the stator. This Figure 1 shows the angular indexing orifice 45 made in the central ring 32 of the brake reaction disk 31 (also visible in Figure 4 ). The pin 46 fits into this orifice 45 and is also inserted into the angular indexing orifice 47 of the hydraulic distributor 18. This thus ensures the angular indexing of the distributor 18 relative to the brake reaction disk 31. Figure 3 ).

[0116] In addition, the external element 2 (and more specifically, the housing 5 in this example) also includes an angular indexing orifice 48 which likewise receives a pin 49 that is also engaged into an angular indexing groove 35 of the squeeze stop 34A of the brake reaction disk 31. This thus ensures the angular indexing of the brake reaction disk 31 relative to the external element 2.

[0117] Thus, the brake reaction disk 31 is a unique component which directly and independently provides the angular indexing of the hydraulic distributor 18 relative to the external element 2. The brake reaction disk 31 is a component with rotational symmetry which can be machined on a lathe without changing the clamping on the workpiece so that its two angular indexing elements 35, 45 can be manufactured with a high level of mechanical precision. Thus, precise angular indexing is ensured at a lower cost which is of primary importance for the operation of the hydraulic distributor 18 and which has a very low level of spread.

[0118] Referring Figure 3 , the brake ring 29 includes a through-orifice 76 through which the squeeze stop 34 can pass. One of these orifices 76A takes the form of a notch which additionally allows the pin 49 to pass through.

[0119] Furthermore, referring Figure 1 and 4 , the hydraulic brake release chamber 50 is located between the brake reaction disk 31 and the passive brake piston 36. In this example, due to the fact that each of these elements is composed of radially-mounted components 33, 39 and axially-mounted components 32, 40 mounted from top to tail and by means of annular seals 38, 42, the brake reaction disk 31 and the passive brake piston 36 delimit between them the hydraulic brake release chamber 50, the annular seals 38, 42 allowing a fluid-tight relative axial translational movement along two coaxial cylindrical bearing surfaces 77, 78.

[0120] Thus, when the hydraulic brake release chamber 50 is pressurized with hydraulic fluid, a separating force is generated between the brake reaction disk 31 and the passive brake piston 36. When designing a hydrostatic machine, the volume of the hydraulic brake release chamber 50 can be adjusted by the diameter difference between the two annular seals 38, 42 and can thus be customized according to the force required to release the passive brake without compromising the improved longitudinal compactness of the hydrostatic machine.

[0121] The arrangement of the brake reaction disk 31 provides the advantage of allowing the use of a central ring 32 with a relatively large internal diameter which in turn makes it possible to provide a distribution hub 4 with a diameter large enough to accommodate the fluid inlet conduit 19 and the fluid outlet conduit 20 which only cause a small pressure drop and to do so without compromising the braking performance and while remaining very compact, especially in terms of length. In this example (seeFigure 1 ), these fluid inlet ducts 19 and fluid outlet ducts 20 advantageously have a large diameter and follow a path that is close to a straight line without bends.

[0122] To supply hydraulic fluid to the hydraulic brake release chamber 50, the hydrostatic machine includes an annular supply chamber 51 located between the brake reaction disc 31 and the distribution hub 4. Both a hub duct 52 (which leads to the outside, to the distribution hub 4 for connection to the hydraulic circuit) and a transfer duct 53 (which additionally leads to the hydraulic brake release chamber 50) lead to the annular supply chamber 51.

[0123] Figure 5 is Figure 4 a detailed view of detail V and shows the mounting of the brake reaction disc 31 on the distribution hub 4.

[0124] Two annular seals 54 are positioned between the brake reaction disc 31 and the distribution hub 4, defining a fluid-tight space therebetween in the gap between these two components. The annular supply chamber 51 is positioned between these two annular seals 54.

[0125] In this example, the annular supply chamber 51 consists of a first discontinuity 56 in the diameter of the central ring 32 of the brake reaction disc 31 and a second discontinuity 57 in the diameter of the distribution hub 4. These two discontinuities 56, 57 are complementary to each other and are axially separated in such a way that the annular supply chamber 51 is defined by these two discontinuities 56, 57, and the two annular seals 54 make the annular supply chamber 51 fluid-tight.

[0126] This configuration makes it possible to create the annular supply chamber 54 while maintaining optimal axial guidance of the translational movement of the brake reaction disc 31 on the distribution hub 4. Additionally, during the manufacture of the hydrostatic machine, due to the change in the diameter of the components caused by the discontinuities 56, 57, the brake reaction disc 31 can be installed by sliding it onto the distribution hub 4 such that the first annular seal 54 does not encounter a cavity other than its own bearing surface, and the same is true for the second annular seal 54. Thus, the two annular seals 54 slide along their respective bearing surfaces without encountering any sharp edges, which constitutes a critical point of this installation.

[0127] By means of the sliding of the annular seal 54 over a stroke, the brake reaction disk 31 slides axially freely by the axial translation of the central ring 32 on the hydraulic distributor 4, this stroke being constrained on one side by an end stop formed by the contact between the central ring 32 and the distribution hub 4 or the first cover 6; and, on the other side, by an end stop 55 which, in this example, consists of a circlip. The end stop 55 can form the end stop of the translational movement of the brake reaction disk 31 in the direction of the brake 21.

[0128] The structure of the annular supply chamber 51 allows this axial sliding while remaining intact.

[0129] The passive braking function is implemented as follows.

[0130] In the case where the hydraulic circuit at the hydraulic braking release chamber 50 is not activated, the elastic element 43 pushes the passive braking piston 36 towards the brake 21, such that it presses the end 41 which pushes the brake ring 29 backwards, and the brake ring 29 itself compresses the set of disks 24, 25 of the brake 21. Given the calibration of the elastic element 43, taking into account the nature of the disks 24, 25, this operation causes the braking and immobilization of the rotor with respect to the stator.

[0131] When the hydrostatic machine comes into operation, in order to enable the rotor to rotate with respect to the stator, the hydraulic braking release chamber 50 is pressurized by the hydraulic fluid conveyed by the hub conduit 52 (which is connected to the hydraulic circuit), the annular supply chamber 51 and the transfer conduit 53.

[0132] This pressurization of the hydraulic braking release chamber 50 causes the brake reaction disk 31 to be brought into abutment against its end stop 55, and the axial movement of the passive braking piston 36 retreats (then the passive braking piston 36 moves away from the brake reaction disk 31) compressing the elastic element 43. This results in the release of the stress applied to the brake ring 29 and thus the release of the brake 21.

[0133] Once the pressure in the hydraulic braking release chamber 50 is no longer maintained, the passive braking piston 36 returns, under the action of the elastic element 43, to its position clamping the brake 21.

[0134] In normal operation, or in the case of overpressure in the hydraulic braking release chamber 50, the brake reaction disk 31 deforms and the four pressing stops 34 come to bear against the shoulders 58 of the external element 2 (in this example, the shoulders 58 are formed directly in the housing 5). For this purpose, when the system is at rest, the dimensions of the brake reaction disk 31 are such that the pressing stops 34 exhibit a small axial clearance with respect to the shoulders 58, for example a clearance of less than 1 mm.

[0135] Therefore, a brake reaction disc 31 with a large diameter can be advantageously used without impairing its operation.

[0136] The brake ring 29 allows the pressure of the passive brake piston 36 to be received at a diameter radially far from the outer side (its extrusion surface 79) of the housing 5, while allowing this pressure to be transmitted through a smaller diameter on its annular braking portion 30. This acting from a larger diameter to a smaller diameter corresponding to the brake 21 means that the passive brake piston 36 can be constructed with a small thickness and a large axial length but a large-diameter axial cylindrical portion 40, thereby making it rigid and forming a component for a large-diameter support surface for sealing at the annular seal 42.

[0137] Figure 4 The cross-sectional view of also shows the discharge conduit 59, which is made in the brake reaction disc 31, in its central ring 32, and axially straight through the brake reaction disc 31. The discharge conduit 59 is also visible in Figure 3 this.

[0138] The discharge conduit 59 allows fluid communication straight through the brake reaction disc 31, such that there is no element separating the hydraulic fluid, and such that despite the presence of the brake reaction disc 31, only a single discharge outlet 60 on the distribution hub 4 is required to discharge the hydraulic fluid.

[0139] In this example, the hydrostatic machine further includes a dynamic brake piston 37, which provides an active braking function under the action of a positive command applied by the operator or device to the brake actuator.

[0140] The dynamic braking function is optional here, and whether or not this dynamic braking function is adopted, the hydrostatic machine has substantially the same structure. Therefore, Figure 6 a variant without the dynamic braking function is shown in a partial cross-sectional view limited to these elements.

[0141] As Figure 1 and 4 shown, when implementing this dynamic braking function, the hydrostatic machine includes a dynamic brake piston 37, which has a sliding hub 61 and an axial cylindrical portion 62.

[0142] The sliding hub 61 is fitted with a seal and is inserted into a dynamic braking chamber 66 made in the external element 2. In this example, the dynamic braking chamber 66 is particularly advantageously formed by a simple tubular protrusion 63 of the first cover 6, using the adjacent inner surface of the housing 5 at the junction of the first cover 6 and the housing 5.

[0143] The axial cylindrical portion 62 of the dynamic braking piston 37 is fitted (as a sliding fit) between the axial cylindrical portion 40 of the passive braking piston 36 and the external element 2 (in this example, the housing 5).

[0144] The axial cylindrical portion 62 of the dynamic braking piston 37 includes a pressing end 64 which is substantially axially aligned with the pressing end 41 of the axial cylindrical portion 40 of the passive braking piston 36. Thus, both of these pressing ends 41, 64 are capable of applying pressure to the pressing surface 79 of the braking ring 29, which is positioned opposite them.

[0145] Figure 7 is a perspective view of the hydrostatic machine as viewed externally from one side including the first cover 6. Figure 7 The dynamic braking conduit 65 made in the external element 2 (in this example, in the cover 6) is shown. The dynamic braking conduit 65 is very short (it corresponds to the thickness of the first cover 6) and leads directly to the dynamic braking chamber 66.

[0146] In order to achieve the dynamic braking function during the operation of the hydrostatic machine, the dynamic braking chamber 66 is thus pressurized by the hydraulic fluid conveyed by the dynamic braking conduit 65. Then, the dynamic braking piston 37 is axially translated towards the brake 21 so that its pressing end 64 acts on the braking ring 29 and activates the brake 21.

[0147] It should be emphasized that an advantage of the dynamic braking piston 37 is that, in addition to being already fitted between the passive braking piston 36 and the external element 2, its translational movement does not require any further guidance. Thus, a very compact fit is obtained for one or even two braking functions. Additionally, the hydrostatic machine remains compact whether or not the optional dynamic braking function is employed.

[0148] The brake reaction disk 31 also has an additional function of releasing the brake during maintenance operations or in case of failure. Figure 8 is a partial cross-sectional view showing a part of the internal element 1 and the external element 2 around the distribution hub 4 for another angular position of the rotor relative to the stator, showing the threaded holes 67 made in the central ring 32 of the brake reaction disk 31.

[0149] In this example, the number of these threaded holes 67 is 4 and they are angularly distributed on the circumference of the brake reaction disk 31.

[0150] These threaded holes 67 match the through holes 68 made in the distribution hub. In this example, these through holes 68 are threaded holes with a diameter larger than that of the threaded holes 67 and, during normal operation, they are plugged by screws 69 in a fluid-tight manner. In Figure 7One of the screw 69 and the threaded holes 68 can also be seen therein.

[0151] According to this brake release function, in the event of a fault or for the purpose of maintenance operations, by positioning the rotor relative to the stator (by a relative rotation of up to a quarter turn) until the threaded holes 67, 68 are aligned, pulling out the screw 69, and then inserting a maintenance screw with a diameter of the screwed thread of the threaded hole 67 having the brake reaction disc 31, such that tightening these maintenance screws pulls the brake reaction disc 31 towards the first cover 6 by a stroke sufficient to release both the passive brake piston 36 and the dynamic brake piston 37 (if the latter exists), it is possible to release all the braking functions.

[0152] Figure 9 is a detailed view particularly illustrating the arrangement of the extrusion stop elements allowing this brake release function. The brake reaction disc 31 includes an axial extrusion stop 70 which is designed to push back a complementary support surface 71 on the passive brake piston 36, and the passive brake piston 36 also includes an axial extrusion stop 72 which is designed to push back a complementary support surface 73 on the dynamic brake piston 37.

[0153] The axial extrusion stop 70 of the brake reaction disc 31 is produced by means of an inclined section 74 of the radial part 33 which extends radially outwards and towards the passive brake piston 36. This inclined section 74 also makes it possible to increase the compactness of the hydrostatic machine.

[0154] In addition, with reference to Figure 4 , the hydraulic distributor 4 can include a threaded angular indexing hole 75 which can be accessed through the discharge conduit 59 and the discharge outlet 60 and which makes it possible to insert a threaded gauging rod during the manufacture of the hydrostatic machine, which rod is angularly indexed and holds the hydraulic distributor 18 on the distribution hub 4 in order to hold these elements together during assembly.

[0155] Embodiment variants can be foreseen. In particular, the entire hydraulic distribution part and the part providing the cooperation between the piston 12 and the cam surface 8 can be different from the parts given here by way of example. In addition, the rotational coupling of the brake reaction disc 31 with the external element 2 can be achieved using other alternatives, for example by fitting the brake reaction disc 31 tightly on the distribution hub 4.

Claims

1. A hydrostatic rotating machine comprising: - an inner element (1) and an outer element (2), which are coaxial and mounted with the ability to rotate relative to each other around an axis of rotation (R), one of these elements being the rotor and the other of these elements being the stator; - a piston (12) movable in the cylinder (11) and cooperating with the cam surface (8) in a manner coordinated with the rotation of the rotor relative to the stator; - a distribution hub (4) rotationally coupled to the external element (2); - a hydraulic distributor (18) mounted on the distributor hub (4) and designed to selectively connect the cylinders (11) to a hydraulic circuit; - a brake (21) designed to resist the rotational movement of the rotor relative to the stator; The hydrostatic rotating machine is characterized in that it comprises: - a brake reaction disc (31) mounted on the distribution hub (4), extending radially around the distribution hub (4) and rotationally coupled to the outer element (2); - a passive brake piston (36) designed to activate the brake (21) under the action of an elastic element (43) and mounted so as to be axially movable relative to the brake reaction disk (31); - A hydraulic brake release chamber (50) positioned between the brake reaction disc (31) and the passive brake piston (36).

2. The rotary hydrostatic machine according to claim 1, characterized in that The brake reaction disc (31) is mounted on the distribution hub (4) with axial translational mobility.

3. The rotary hydrostatic machine according to claim 2, characterized in that It comprises an end stop (55) which stops the axial translation of the brake reaction disc (31) in the direction of the brake (21).

4. A rotary hydrostatic machine according to any one of the preceding claims, characterised in that It comprises an annular supply chamber (51) positioned between the distribution hub (4) and the brake reaction disc (31), the annular supply chamber (51) being connected on the one hand to the hydraulic brake release chamber (50) and on the other hand to a hub duct (52) extending from the distribution hub (4).

5. The rotary hydrostatic machine according to claim 4, characterized in that The annular supply chamber (51) is delimited by two annular seals (54) positioned between the distribution hub (4) and the brake reaction disk (31).

6. A rotary hydrostatic machine according to any one of claims 4 or 5, characterised in that The annular supply chamber (51) is defined by two interruptions of complementary diameters of the distribution hub (4) and the brake reaction disc (31), respectively.

7. A rotary hydrostatic machine according to any one of the preceding claims, characterised in that The brake reaction disc (31) includes: a center ring (32) extending axially and mounted on the distribution hub (4); and a radial portion (33) extending radially from the center ring (32).

8. The rotary hydrostatic machine according to claim 7, characterized in that The central ring (32) of the brake reaction disc (31) comprises an outer cylindrical bearing surface (77), and the passive brake piston (36) is a component with rotational symmetry comprising a central opening, and the passive brake piston (36) is mounted on the distribution hub (4) by mounting the inner periphery of the central opening on the cylindrical bearing surface (77).

9. A rotary hydrostatic machine according to any one of claims 7 or 8, characterised in that The radial portion (33) of the brake reaction disk (31) has an inclined section (74) extending radially outward and toward the passive brake piston (36).

10. A rotary hydrostatic machine according to any one of the preceding claims, characterised in that The passive brake piston (36) comprises a radial portion (39) and an axial cylindrical portion (40) comprising a pressing end (41) designed to activate the brake (21).

11. The rotary hydrostatic machine of claim 10, wherein: The axial cylindrical portion (40) of the passive brake piston (36) includes an inner cylindrical bearing surface (78) mounted on the brake reaction disk (31).

12. A rotary hydrostatic machine according to any one of the preceding claims, characterised in that The hydraulic brake release chamber (50) is closed by two annular seals (38, 42) each positioned between the brake reaction disc (31) and the passive brake piston (36).

13. A rotary hydrostatic machine according to any one of the preceding claims, characterised in that The brake reaction disc (31) comprises squeeze stops (34) distributed angularly on its circumference, facing toward the brake (21) and positioned opposite a shoulder (58) of the outer element (2).

14. A rotary hydrostatic machine according to any one of the preceding claims, characterised in that The brake reaction disk (31) is indexed at an angle to the hydraulic distributor (18) and the external element (2) by means of pins (46, 49).

15. A rotary hydrostatic machine according to any one of the preceding claims, characterised in that It comprises a brake ring (29), which comprises: an annular brake portion (30) designed to activate a brake (21); and a pressing surface (79) on which a passive brake piston (36) is designed to press; the pressing surface (79) is located radially outward relative to the annular brake portion (30).

16. A rotary hydrostatic machine according to claim 15 when dependent on claim 13, characterised in that The brake ring (29) comprises a through-opening (76) through which the extrusion stop (34) can pass.

17. A rotary hydrostatic machine according to any one of the preceding claims, characterised in that The brake reaction disc (31) includes a drain conduit (59) extending straight axially therethrough.

18. The rotary hydrostatic machine of claim 17, wherein: The distribution hub includes a discharge outlet (60), and the hydraulic distributor (18) includes a threaded retaining hole (75), and the discharge conduit (59), the discharge outlet (60) and the threaded retaining hole (75) are designed to be aligned along an axis parallel to the rotation axis (R).

19. A rotary hydrostatic machine according to any one of the preceding claims, characterised in that It comprises a dynamic brake piston (37) comprising an extrusion end (64) which is substantially axially aligned with an extrusion end (41) of the passive brake piston (36).

20. The rotary hydrostatic machine of claim 19, wherein: The dynamic brake piston (37) comprises an axial cylindrical portion (62) which is fitted between the passive brake piston (36) and the external element (2).

21. The rotary hydrostatic machine of claim 20, wherein: The dynamic brake piston (37) includes a sliding hub (61) which is inserted into a dynamic brake chamber (66) formed in the outer member (2).

22. A rotary hydrostatic machine according to any one of claims 2 to 21, characterised in that The brake reaction disc (31) comprises: an axial extrusion stop (70) designed to be axially extruded on a complementary bearing surface (71) provided on the passive brake piston (36); and at least one threaded hole (67) designed to be aligned with a through hole (68) made in the distribution hub (4).

23. A rotary hydrostatic machine according to claim 22 when dependent on claim 19, characterised in that The passive brake piston (36) comprises an axial pressing stop (72) which is designed to press against a complementary bearing surface (73) of the dynamic brake piston (37).

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