Hydraulic motor comprising a duct for air circulation

Abstract

The present invention relates to a hydraulic motor (1), comprising a rotor (2) pivotally mounted in a casing (31), this rotor (2) comprising a main shaft (21), of which a first end is suitable for carrying a wheel and a second end is located in the casing (31), the main shaft (21) having an air duct (212) which opens onto the first end of the main shaft (21) and onto the second end of the main shaft (21) at the axis of rotation (10). This hydraulic motor comprises a hydraulic actuator (5) for driving the rotor (2) in rotation. According to the invention, the rotor (2) comprises a secondary shaft (22), of which a first end is connected to the second end of the main shaft (21), the secondary shaft (22) having an air duct (222) which is connected to a compressed air supply and opens onto the first end of the secondary shaft (22) at the axis of rotation (10).

Description

Hydraulic motor including a conduit for air circulation

[0001] The present invention relates to hydraulic machines, and more specifically to hydraulic motors driving the wheels of vehicles.

[0002] In particular, the invention relates to a hydraulic motor comprising a means for controlling the inflation pressure of the tire of a wheel driven by the hydraulic motor.

[0003] It is known to drive vehicle wheels using hydraulic motors. In such cases, the vehicle wheel, often consisting of a rim surrounded by a tire, may be mounted directly onto a mounting plate forming one end of the hydraulic motor's rotor.

[0004] In some vehicles, it is useful to be able to control the tire pressure using an air pump located inside the vehicle, allowing adjustments to be made by increasing or decreasing the tire pressure. Such pressure control during vehicle operation allows for varying the contact patch of the tires with the ground. This is particularly useful for agricultural machinery or construction equipment, enabling them to adapt optimally to the terrain they are operating on. For agricultural machinery, this pressure control is especially useful for inflating tires to low pressure to avoid compacting the soil during operation, and to high pressure for faster travel on roads or tracks, resulting in better directional control, reduced tire wear, and fuel savings.

[0005] To perform such a tire pressure check, it is necessary to provide an air supply line in the rotor of the hydraulic motor, which carries the wheel.

[0006] The implementation of such an air supply line is described in document FR3068300A1, submitted on behalf of the Applicant. This document proposes an air supply line within the shaft forming the motor rotor, from its proximal end, which forms a mounting plate for a wheel, to its opposite distal end. This configuration requires that the hydraulic motor be equipped with compressed air supply means located at the distal end of the shaft.

[0007] It is sometimes necessary to equip hydraulic motors intended to drive vehicle wheels with braking systems. As is known, notably from document FR2683882A filed on behalf of the Applicant, such a braking system can be carried by a specific brake shaft, separate from the main shaft carrying the vehicle wheel, but assembled at the distal end of the main shaft so as to be rotationally coupled to it. The presence of such a brake shaft prevents the implementation of compressed air supply means at the distal end of the main shaft.

[0008] Alternatively, air supply lines are also known in the rotor of hydraulic motors, from the proximal end of this rotor forming a mounting plate for a wheel to one or more radial openings.

[0009] Such radial openings in the air supply ducts can lead to a peripheral compressed air supply chamber surrounding the periphery of the rotor. This design, notably described in US patent 4844138A, necessitates the implementation of a peripheral air supply chamber around the rotor shaft, in an area of ​​the engine typically occupied by hydraulic actuation means and shaft support bearings. It therefore requires a special engine design.

[0010] Furthermore, such a peripheral air supply chamber must be separated from adjacent areas of the engine that are at least partially filled with oil. This separation is generally achieved by sliding peripheral seals, which may not provide a perfect seal. Leaks can then lead to compressed air entering the oil, or conversely, oil entering the compressed air, which can be problematic.

[0011] The present invention aims to overcome at least some of the drawbacks of the prior art.

[0012] Its main objective is to facilitate the implementation of an air supply to a wheel driven by a hydraulic motor.

[0013] Its primary objective is to enable the creation of large diameter air passages to supply the wheel with air, allowing for very rapid changes in tire pressure on this wheel, particularly when the machine changes configuration.

[0014] These objectives, as well as others which will become clearer later, are achieved using a hydraulic motor, comprising a rotor mounted pivoting in a casing, around an axis of rotation, the rotor comprising a main shaft having, along the axis of rotation, a first end, located outside the casing, and adapted to carry a wheel, and a second end, located inside the casing, the main shaft having an air duct, a first end of this air duct opening onto the first end of the main shaft and a second end of this air duct opening onto the second end of the main shaft, at the level of the axis of rotation, the hydraulic motor comprising a hydraulic actuator capable of driving the rotor in rotation in the casing under the effect of a hydraulic pressure.According to the invention, the rotor comprises a secondary shaft, this secondary shaft having, along the axis of rotation, a first end connected to the second end of the main shaft by a link capable of transmitting the rotation around the axis of rotation; the secondary shaft having an air duct, a first end of this air duct opening onto the first end of the secondary shaft, at the level of the axis of rotation, and a second end of this air duct being connected to a compressed air supply.

[0015] The air lines from the main shaft and the secondary shaft open opposite each other at the axis of rotation, allowing them to communicate. Compressed air can then be routed to the wheel through the main and secondary shafts. This advantageously allows the compressed air supply for the rotor's air lines to be located away from the wheel.

[0016] Advantageously, the main shaft air duct extends into the main shaft along the axis of rotation.

[0017] Thus, this air duct can advantageously have a large diameter without weakening the main shaft or disrupting its balance. Furthermore, the fact that the air duct terminates at the first end of the main shaft at the axis of rotation facilitates the connection of the tire's air supply.

[0018] Preferably, the connection between the first end of the secondary shaft and the second end of the main shaft includes sealing means suitable for ensuring the sealing of the connection between the first end of the air duct of the secondary shaft and the second end of the air duct of the main shaft.

[0019] Such sealing methods can be simple and effective, with the main shaft and secondary shaft being static relative to each other.

[0020] According to an advantageous embodiment, the secondary shaft and the housing have complementary means capable of cooperating to brake the rotation of the rotor relative to the housing.

[0021] According to one embodiment, the second end of the secondary shaft air duct opens onto a second end of the secondary shaft, at the level of the axis of rotation.

[0022] According to another embodiment, the secondary shaft air duct opens onto the periphery of the secondary shaft, opposite a peripheral supply chamber formed between the housing and the secondary shaft, the peripheral supply chamber being supplied with compressed air, the peripheral supply chamber being separated from the rest of the internal volume of the housing, on both sides, by specific sealing means, each of the specific sealing means having: a first peripheral seal closing the space between the housing and the rotor, around the rotor, a second peripheral seal closing the space between the housing and the rotor, around the rotor, a peripheral isolation chamber, located between the first peripheral seal and the second peripheral seal, this peripheral isolation chamber being connected to a drain allowing the evacuation of fluids present in the peripheral isolation chamber.

[0023] This embodiment advantageously allows the compressed air supply to be implemented through a lateral face of the rotor, while avoiding the risk of fluid leakage between the compressed air supply and the internal volume of the casing.

[0024] Preferably, this drain allowing the evacuation of fluids present in the peripheral isolation chamber is separate from the drain draining the internal volume of the crankcase.

[0025] The invention will be better understood upon reading the following description of preferred embodiments, given by way of simple figurative and non-limiting example, and accompanied by the figures, among which: Figure 1 is a cross-sectional view, along a plane passing through the axis of rotation, of a hydraulic motor according to a first embodiment of the invention. Figure 2 is a detailed cross-sectional view, along a plane passing through the axis of rotation, of a portion of the secondary shaft and the housing of a hydraulic motor according to a variant of the configuration shown in Figure 3. Figure 4 is a detailed cross-sectional view, along another plane passing through the axis of rotation, of a portion of the secondary shaft and the housing of the hydraulic motor according to the variant shown in Figure 5. Figure 6 is a cross-sectional view, along a plane passing through the axis of rotation, of a hydraulic motor according to another configuration.

[0026] Laest an axial section, along a plane passing through the axis of rotation, of a hydraulic motor according to a first embodiment of the invention.

[0027] This hydraulic motor 1 comprises a rotor 2, or rotating part, mounted to rotate about an axis 10 within a stator 3, or fixed part. It also includes a hydraulic actuator 5 for driving the rotor 2 in rotation within the stator 3.

[0028] The stator 3 mainly comprises a housing 31 intended to be attached to a vehicle chassis. In other cases, when the hydraulic motor is intended to drive a steering wheel, the housing 31 can be coupled to the vehicle chassis by means of a pivot allowing the assembly formed by the hydraulic motor and the wheel to pivot relative to the chassis.

[0029] The rotor, pivoting around a rotation axis 10, includes a main shaft 21 forming a wheel spindle.

[0030] At one of its ends on the axis 10, arbitrarily called the "proximal end," the main shaft 21 has a wheel support portion 211, forming a mounting plate for attaching the rim of a wheel fitted with a tire. This wheel support portion 211 is located outside the housing 31.

[0031] From this end, the main shaft 21 extends into a generally cylindrical portion centered on the axis 10, which runs within the housing 31. The surface of this portion of the shaft located between its ends is hereafter referred to as the "peripheral surface" of the shaft. This generally cylindrical portion is assembled to the housing 31 by a bearing housing comprising two tapered roller bearings 41 and 42 mounted in an O configuration. Alternatively, bearings can of course be mounted in any other configuration known to those skilled in the art.

[0032] The second end of the main tree 21 on the axis 10, opposite its proximal end, is arbitrarily called the "distal end" of the main tree 21.

[0033] The hydraulic actuator 5, which drives the rotor 2 in rotation within the stator 3, is connected to the high-pressure and low-pressure lines of a hydraulic supply circuit. It comprises, in a manner known per se, a cylinder block 51 connected to the rotor and a multi-lobe cam 52 connected to the stator, arranged around the cylinder block 51.

[0034] The cylinder block 51 defines a plurality of housings in which slide pistons 53 arranged radially with respect to the axis of rotation 10. In the embodiment shown, this cylinder block 51 is linked to the main shaft 21 by means of splines associating it with this main shaft 21 in rotation around the axis 10.

[0035] A hydraulic distributor is connected to the high-pressure outlet of the hydraulic motor, which is connected to a high-pressure line, and to the low-pressure outlet of the hydraulic motor, which is connected to a low-pressure return line. It allows the hydraulic pressure in the cylinder block housings to be varied, thereby changing the position of the pistons 53 within the cylinder block 51. The pistons 53, advantageously carrying cylindrical rollers, cooperate with the multi-lobe cam 52 to drive the rotor 2 in rotation relative to the stator 3.

[0036] In closed-loop hydraulic circuits, the high-pressure line is supplied by a hydraulic power source and typically operates at a pressure of 200 to 600 bar. The low-pressure return line typically operates at a pressure of 5 to 20 bar. The hydraulic power source is supplied both by the low-pressure return line and by a non-pressurized hydraulic reservoir.

[0037] In open-loop hydraulic circuits, the hydraulic distributor is connected to a high-pressure line and a pressureless return line. The high-pressure line is supplied by a power pump, which draws from a pressureless reservoir. The return line is directly connected to the reservoir.

[0038] Of course, any other hydraulic actuator known to a person skilled in the art can be used to drive the rotor 2 in rotation relative to the stator 3.

[0039] The space within the housing 31, around the rotor 2 and the hydraulic actuator 5, is called the internal volume 310, or housing volume. This internal volume 310 receives the hydraulic leaks from the hydraulic actuator 5 and is connected to a return line to the oil reservoir, via a drain port in the housing and a drain line to the oil reservoir.

[0040] In the embodiment represented by the, the rotor 2 includes a secondary shaft 22. This secondary shaft 22 extends along the axis 10 and has a first end on this axis 10, arbitrarily called the "proximal end", which is assembled to the distal end of the main shaft 21 in such a way that the secondary shaft is mobile in rotation, around the axis 10, with the main shaft 21.

[0041] For this assembly, the peripheral surfaces of the main shaft 21, near its distal end, and of the secondary shaft 22, near its proximal end, have grooves. These grooves correspond to internal grooves in the cylinder block 51. The interaction of the grooves of these two shafts with the grooves of the cylinder block 51 allows the main shaft 21, the secondary shaft 22, and the cylinder block 51 to be rotated around the axis 10.

[0042] The second end of the secondary tree 22 on the axis 10, opposite its proximal end, is arbitrarily called the "distal end" of the secondary tree 22. The surface of the portion of the tree located between its ends is subsequently called the "peripheral surface" of the tree.

[0043] As is known in itself, this secondary shaft 22 is a brake shaft. It carries a toothed wheel 221 which is surrounded by an internally toothed ring 32, connected to the stator 3, without contact between the toothed wheel 221 and the ring 32. A brake disc 6, movable in translation about the axis 10, allows keys 61 to be inserted between the toothed wheel 221 and the ring 32, thus connecting the toothed wheel 221 and the ring 32 in rotation, which has the effect of immobilizing the rotor 2 relative to the stator 3.

[0044] Such a brake is known to those skilled in the art and will not be described in further detail.

[0045] Advantageously, the hydraulic motor 1 according to the invention includes a conduit for air circulation, suitable for sending air, from a source of compressed air, to the tires of the wheel carried by the main shaft 21.

[0046] For this purpose, in the embodiment represented by the, the main shaft 21 has an air duct 212 opening on the one hand at the proximal end of the main shaft 21 and on the other hand at the distal end of this main shaft 21. Advantageously, this air duct extends along the axis of rotation 10 and opens at the level of this axis of rotation 10 on the proximal end and on the distal end of the shaft.

[0047] The opening of the pipe at the axis of rotation, on the proximal end, makes it easier to connect to this air pipe an inflation hose carried by the rim of the wheel, in order to bring compressed air to the tire.

[0048] In the embodiment represented by the, the secondary shaft 22 also has an air conduit 222, the first end of which opens at the proximal end of this secondary shaft 22, at the axis of rotation 10.

[0049] When the proximal end of the secondary shaft 22 is assembled to the distal end of the main shaft 21, the openings of the air duct 212 of the main shaft 21 and the air duct 222 of the secondary shaft 22 face each other, allowing air to flow between these air ducts 212 and 222.

[0050] Advantageously, the assembly of the proximal end of the secondary shaft 22 with the distal end of the main shaft 21 is carried out so as to ensure a tight connection between the air lines 212 and 222.

[0051] Thus, in the embodiment shown, the proximal end of the secondary shaft 22 has a nipple 223 centered on the axis 10, the air duct 222 of the secondary shaft 22 opening onto this nipple 223. The distal end of the main shaft 21 has a cylindrical bore 213, of a diameter substantially identical to that of the nipple 223 and centered on the axis 10, the air duct 212 of the main shaft 21 opening into this bore 213. For the assembly of the proximal end of the secondary shaft 22 with the distal end of the main shaft 21, the nipple 223 is inserted into the bore 213.

[0052] A seal 2231, inserted into a peripheral groove of the stud 223, ensures the sealing of the assembly. The main shaft 21 and the secondary shaft 22 rotate together, as they are connected by the splines of the cylinder block 51. Consequently, the seal 2231 is mounted in a purely static manner and does not experience wear from friction.

[0053] A second end of the air line 222 of the secondary shaft 22 advantageously opens onto a compressed air supply. Thus, in the embodiment shown in the figure, the air line 222 extends along the axis 10 and opens at the distal end of the secondary shaft 22, at the level of this axis 10.

[0054] Advantageously, this air line 222 opens, at the distal end of the secondary shaft 22, into a compressed air supply. Preferably, a rotary joint system is provided between the secondary shaft 22 and the stator, which carries the compressed air supply, in order to prevent any compressed air leakage into the internal space of the motor.

[0055] The compressed air supply can, for example, consist of a pressurized chamber placed at the end of the secondary shaft 22, which is connected by suitable pipes to a compressed air source, carried by the vehicle and capable of inflating the tires, such as a compressor or a compressed air cylinder.

[0056] By varying the air pressure in this pressurized chamber, it is possible to vary in the same way the air pressure in the tire of the wheel carried by the motor 1, which is connected to the pressurized chamber by the air lines 212 and 222.

[0057] The air ducts in the main and secondary shafts of engine 1 offer several advantages.

[0058] On the one hand, they allow the engine to have one or more secondary shafts, offering additional functions such as, for example, braking, while also having an air line capable of inflating the tire of the wheel carried by the engine.

[0059] On the other hand, they allow the air supply means for these air lines to be placed at the level of an area of ​​the engine 1 which is not obstructed by the hydraulic actuators.

[0060] Furthermore, the axial position of the air ducts at the distal end of the main shaft and the proximal end of the secondary shaft allows for easy assembly of these shafts, without the need to place them in particular angular positions.

[0061] Axially extending air ducts can also have relatively large diameters without significantly weakening the main and secondary shafts. This is because the maximum mechanical stresses experienced by the shafts are located near their radial outer wall, while the central portion of the shafts receives little stress. Therefore, it is possible to drill large holes in the center of the shafts without significantly weakening them. Such large-diameter air ducts allow for particularly rapid inflation and deflation of the tires.

[0062] Finally, being centered on the axis of rotation, these air ducts do not cause any imbalance of the main and secondary axes, which avoids any vibration during their rotation.

[0063] In a variant of the embodiment shown in the figure, it is also possible that the air duct 222 provided in the secondary shaft 22 has a different shape. Thus, it is possible that one end of this air duct opens at the axis of rotation 10 onto the proximal end of the secondary shaft 22, as in the embodiment shown in the figure, but that another end of this air duct 222 opens radially onto a lateral wall of the secondary shaft 22.

[0064] Such an air duct 222 can for example be formed by a first drilling made along the axis 10 from the proximal end of the secondary shaft 22, and not crossing the entire secondary shaft 22, and by at least a second drilling made radially in the secondary shaft 22, perpendicular to the axis 10 and passing through this axis 10. These drillings, communicating with each other at the axis 10, then form the air duct 222.

[0065] In such a case, the second end of the air line 222 can open into a peripheral chamber 71 located between the secondary shaft 22 and the housing 31, this peripheral chamber 71 surrounding a portion of the periphery of the secondary shaft 22 and forming a pressurized chamber which is connected by lines 72 adapted to a source of compressed air.

[0066] In such a case, such a peripheral chamber 71 must be sufficiently isolated from the internal volume 310 of the housing 31, to prevent leaks of compressed air from the peripheral chamber 71 into the internal volume 310, or leaks of oil from the internal volume 310 into the peripheral chamber 71.

[0067] Indeed, oil leaks in the compressed air system must be avoided to prevent damage to the tires or the air compression system. Similarly, compressed air leaks into the engine's internal chamber 310 must be avoided to prevent disrupting the lubrication of this chamber and causing pressure surges and noise in the drainage system. Furthermore, such compressed air leaks into the engine's internal chamber 310 could cause oil emulsification within the chamber, potentially disrupting the unpressurized oil reservoir and causing it to overflow. Finally, if such an emulsion were drawn into the lift pump, it could cause cavitation and changes in fluid compressibility, disrupting the transmission of driving power, particularly by interfering with the operation of the power pump and hydraulic motor.

[0068] It is therefore necessary to implement specific sealing methods to prevent any passage of fluid between the peripheral chamber 71 and the internal volume 310 of the engine.

[0069] Figures 2 and 3 are detailed cross-sectional views, along two separate planes passing through axis 10, of a portion of the secondary shaft 22 and the housing 31 in such a configuration.

[0070] The diagram shows the peripheral chamber 71 located between the secondary shaft 22 and the housing 31, this peripheral chamber surrounding the secondary shaft 22. It also shows the air supply line 72 to the peripheral chamber 71. This air supply line 72 can itself be connected by suitable lines to a compressed air source carried by the vehicle and capable of inflating a tire, which ensures the pressurization of the peripheral chamber 71. The peripheral chamber 71 can, for example, be formed by a peripheral groove in the secondary shaft 22, or by a groove in the housing 31, or by the combination of a groove in the secondary shaft 22 and a groove in the housing 31.

[0071] In the configuration shown in the figure, a portion of the air duct extending radially from the air duct 222 extends into the cutting plane and is therefore visible. The air duct 222 can advantageously include several radially extending portions, for example, formed by several radial holes between the peripheral chamber 71 and the portion of the air duct 222 that extends along the axis of rotation 10. For example, these radially extending portions of the air duct 222 can be formed by three regularly spaced holes. In this way, it is possible to obtain a very large airflow in the air duct 222 without weakening the secondary shaft 22.

[0072] To prevent any leakage between the peripheral chamber 71 and the internal volume 310, it is necessary to put in place specific sealing means on both sides of the peripheral chamber 71.

[0073] Each of these specific sealing means consists of two successive peripheral seals 731 and 732, each of these seals ensuring sliding contact with the housing 31 and / or with the secondary shaft 22, to close the space between this housing 31 and this secondary shaft 22. Each of these specific sealing means also includes a peripheral insulating chamber 733, located between the housing 31 and the secondary shaft 22, surrounding the secondary shaft 22 between the two peripheral seals 731 and 732. Each of the peripheral insulating chambers 733 can, for example, be formed by a peripheral groove in the secondary shaft 22, or by a groove in the housing 31, or by the combination of a groove in the secondary shaft 22 and a groove in the housing 31.

[0074] Each seal 731 therefore provides a seal between the peripheral chamber 71 and one of the peripheral insulation chambers 733. Each seal 732 provides a seal between one of the peripheral insulation chambers 733 and the internal volume 310 of the housing, which may be filled with oil. Each of the seals 731 and 732 can preferably be a composite seal consisting of a sliding ring made of a hard material, for example, a plastic, which acts as a pad, complemented by a rubber O-ring for pressure and sealing. Such seals are known to those skilled in the art to be resistant to friction and pressure surges.

[0075] The peripheral isolation chambers 733 of the specific sealing means are designed to collect any oil or air leaks passing through the seals 731 and 732. Each of these peripheral isolation chambers 733 is connected to a drain, or discharge pipe 74. The discharge pipe 74 allows each of these peripheral isolation chambers 733 to be emptied, for example, by gravity or under pressure. In this configuration, no radial portion of the air pipe 222 is located in the cutting plane.

[0076] It should be noted that such a solution of air duct circulating in a shaft of the hydraulic motor and opening on the periphery of this shaft in a pressurized peripheral chamber whose sealing, with respect to the internal volume of the casing, is ensured by specific sealing means, can also be implemented on a motor comprising only an air duct in the main shaft.

[0077] Lare represents such a hydraulic motor 11. The elements of this motor 11 which are similar or have the same function as the elements of the motor 1 described previously will be designated by the same numerical references.

[0078] This hydraulic motor 11 comprises a rotor 2 consisting of a main shaft 21, which rotates about an axis 10 within a stator 3 comprising, in particular, a housing 31. A first end on the axis 10 of the main shaft, called the proximal end, is designed to support a wheel. The main shaft 21 is assembled to the housing 31 by two tapered roller bearings 41 and 42. A hydraulic actuator 5, of a type known to those skilled in the art, drives the rotor 2 in rotation within the stator 3. It is connected to the high-pressure (HP) line and the low-pressure (LP) line of a hydraulic circuit.

[0079] The main shaft 21 has an air duct 212 opening on one side onto the proximal end of the main shaft 21 at the axis of rotation 10, and on the other side radially onto a lateral wall of the main shaft 21. This air duct is advantageously formed by two non-through holes, one axial and the other radial, which meet at the axis 10.

[0080] The radial opening of the air duct 212 leads to a peripheral chamber 71 located between the main shaft 21 and the housing 31 and surrounding the periphery of the main shaft 21. This peripheral chamber 71 is connected by a duct 72 to air supply means allowing it to be pressurized.

[0081] Specific sealing means are provided between the peripheral chamber 71 and the internal volume 310 of the housing 31. These specific sealing means are advantageously similar to those described in relation to Figures 2 and 3. Each of these specific sealing means consists of two successive peripheral seals 731 and 732, closing the space between the housing 31 and the main shaft 21, and a peripheral isolation chamber 733 located between the housing 31 and the main shaft 21, surrounding the main shaft 21 between the two peripheral seals 731 and 732. A drain, or discharge conduit 74, allows the drainage of each of these peripheral isolation chambers 733 to an oil reservoir R.

[0082] This drain line 74 is advantageously separate from the drain that drains the internal volume of the crankcase. Such a dedicated drain line prevents emulsification in the oil reservoir supplying the pump by directing the flow from drain line 74 away from the pump's suction point. It is also possible to equip the inlet of drain line 74 into the reservoir with a defoaming device, allowing for the separation of air and oil.

[0083] Thus, the present description relates to a hydraulic motor, comprising a rotor mounted pivoting in a housing, around an axis of rotation, said rotor having a first end, located outside said housing, and adapted to carry a wheel, a portion of said rotor being located in said housing, a space called the "internal volume of the housing" separating said rotor from said housing, said rotor having an air duct, a first end of said air duct opening onto said first end, said hydraulic motor comprising a hydraulic actuator capable of driving said rotor in rotation within said housing under the effect of hydraulic pressure, a second end of said duct of said rotating part opening onto the periphery of said rotor, opposite a peripheral chamber formed between said housing and said rotor, said peripheral chamber being connected to a compressed air supply,said peripheral chamber being separated from the rest of said internal volume of the casing, on both sides, by specific sealing means, each of said specific sealing means having: a first peripheral seal closing the space between said casing and said rotor, around said rotor, a second peripheral seal closing the space between said casing and said rotor, around said rotor, a peripheral isolation chamber, located between said first peripheral seal and the second peripheral seal, said peripheral isolation chamber being connected to a drain allowing the evacuation of fluids present in said peripheral isolation chamber.

[0084] Advantageously, said air duct opens onto said first end of said rotor at the level of the axis of rotation.

[0085] According to one embodiment, the rotor may comprise a single shaft, in which said air conduit is drilled.

[0086] According to one embodiment, the rotor may comprise several shafts assembled one to the other along the axis of rotation, the air duct being pierced at least in the shaft forming said first end of said rotor.

[0087] Advantageously, said drain is separate from the drain draining said internal volume of the crankcase.

Claims

A hydraulic motor (1) comprising a rotor (2) pivotally mounted in a housing (31) about an axis of rotation (10), said hydraulic motor comprising a hydraulic actuator (5) capable of driving said rotor (2) in rotation within said housing (31) under the effect of hydraulic pressure, said rotor (2) comprising a main shaft (21) having, along said axis of rotation (10), a first end located outside said housing (31) and adapted to carry a wheel, and a second end located inside said housing (31), said main shaft (21) having an air duct (212), a first end of said air duct (212) opening onto said first end of said main shaft (21) and a second end of said air duct (212) opening onto said second end of said main shaft (21), at the level of said axis of rotation (10), characterized in that said rotor (2) comprises a secondary shaft (22),said secondary shaft (22) having, along said axis of rotation (10), a first end, said first end of said secondary shaft (22) being connected to said second end of said main shaft (21) by a link capable of transmitting rotation about said axis of rotation (10), said secondary shaft having an air duct (222), a first end of said air duct (222) opening onto said first end of said secondary shaft (22) at said axis of rotation (10), and a second end of said air duct (222) being connected to a compressed air supply. Hydraulic motor according to the preceding claim, characterized in that said air conduit (212) of said main shaft (21) extends in said main shaft (21) along said axis of rotation (10). Hydraulic motor according to any one of the preceding claims, characterized in that said connection between said first end of said secondary shaft (22) and said second end of said main shaft (21) comprises sealing means suitable for ensuring the sealing of the connection between said first end of said air line (222) of said secondary shaft (22) and said second end of said air line (212) of said main shaft (21). Hydraulic motor according to any one of the preceding claims, characterized in that said secondary shaft (22) and said housing (31) have complementary means capable of cooperating to brake the rotation of said rotor (2) relative to said housing (31). Hydraulic motor according to any one of the preceding claims, characterized in that said second end of said air line (222) of said secondary shaft (22) opens onto a second end of said secondary shaft (22), at the level of said axis of rotation (10). Hydraulic motor according to any one of claims 1 to 4, characterized in that said air conduit (222) of said secondary shaft (22) opens onto the periphery of said secondary shaft (22), opposite a peripheral supply chamber (71) formed between said housing (31) and said secondary shaft (22), said peripheral supply chamber (71) being supplied with compressed air, said peripheral supply chamber (71) being separated from the rest of said internal volume of said housing, on both sides, by specific sealing means, each of said specific sealing means having: a first peripheral seal closing the space between said housing and said rotor, around said rotor, a second peripheral seal closing the space between said housing and said rotor, around said rotor, a peripheral isolation chamber, located between said first peripheral seal and said second peripheral seal,said peripheral isolation chamber being connected to a drain (74) allowing the evacuation of fluids present in said peripheral isolation chamber. Hydraulic motor according to the preceding claim, characterized in that said drain allowing the evacuation of fluids present in said peripheral isolation chamber is distinct from the drain draining said internal volume of said housing.

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