FR3086715A1 - HYDRAULIC CONTROL DEVICE FOR CONTROLLING A WET CLUTCH - Google Patents

Abstract

The invention relates to a hydraulic control device for controlling a wet clutch (11), the hydraulic control device comprising - a casing (27) comprising an internal tube (28) extending axially around the axis X, said casing (27) comprising an annular chamber (36) formed radially around the internal tube (28); and - an annular piston (25) mounted axially movable in said annular chamber (36); in which the casing (27) comprises a network for the passage of a fluid which comprises at least a first portion (47) formed radially outside or inside the annular chamber (36) and arranged to conduct the fluid up to a front portion (37) of the piston (25) and in which said front portion (37) of the piston (25) comprises at least one through hole (50, 51) allowing the passage of the fluid through said piston (25 ).

Description

Technical area

The invention relates to the field of torque transmission systems for a motor vehicle comprising a wet clutch and in particular relates to a hydraulic control device for such a torque transmission system.

Technological background

Wet clutches include a sealed casing inside which are housed an input disc holder and an output disc holder, movable in rotation relative to each other about an X axis, and an assembly multidisk comprising plates which are integral in rotation with one of the disc carriers and friction disks interposed between the plates and which are integral in rotation with the other of the disk carriers. The plates and the friction discs are axially movable between a disengaged position and a engaged position making it possible to transmit a torque between the disc carriers.

Certain wet clutches are actuated by a hydraulic control system comprising an annular chamber and an annular piston mounted axially movable inside the annular chamber. The annular piston carries a rotary stop which is in abutment against a force transmission member which also cooperates with the multi-disc assembly so that the axial translation of the annular piston in the chamber is able to move the multi-disc assembly between its position disengaged and its position engaged.

In wet clutches, it is essential to ensure efficient oil circulation in order to ensure sufficient cooling and lubrication of the components of the wet clutch, such as the multi-disc assembly and the various rolling bearings for example.

summary

An idea underlying the invention is to provide a hydraulic control device for controlling a wet clutch which is able to improve the circulation of fluid.

According to one embodiment, the invention provides a hydraulic control device intended for controlling a wet clutch comprising an input disc port and an output disc carrier movable in rotation relative to each other around an X axis and a multidisk assembly comprising at least one friction disc integral in rotation with one of the input and output disc holders and at least two plates respectively disposed on either side of said friction disc and integral in rotation with the other of the input and output disc carriers, said multidisc assembly being axially movable between a disengaged position and a engaged position in which the plates pinch the friction disc so as to transmit a torque between the carrier - input disc and output disc holder, the hydraulic control device comprising

- a housing comprising an internal tube extending axially around the axis X, said housing comprising an annular chamber formed radially around the internal tube; and

- An annular piston mounted axially movable in said annular chamber between a engaged position and a disengaged position, said piston having a front portion which projects axially beyond the annular chamber;

in which the casing comprises a network for the passage of a fluid which comprises at least a first portion formed radially outside or inside the annular chamber and arranged to conduct the fluid to the front portion of the piston and wherein said front portion of the piston has at least one through hole allowing the passage of fluid through said piston.

Thus, thanks to the bore (s) made in the front part of the piston, said front part no longer forms an obstacle to the circulation of the fluid, which makes it easier to access the fluid to certain elements arranged. close to the piston, such as a rotary stop carried at the front end of the piston, a clutch support bearing intended to be supported by the internal tube opposite the front portion of the piston and / or an articulation d 'A force transmission member intended to transmit an actuating force from the piston to the multi-disc assembly of the wet clutch.

According to other advantageous embodiments, such a hydraulic control device may have one or more of the following characteristics.

According to one embodiment, the inner tube is intended to receive a support bearing for the wet clutch.

According to one embodiment, the fluid is a cooling and / or lubrication fluid.

According to one embodiment, the fluid is oil, such as gearbox oil.

According to one embodiment, the at least one bore passes radially through the front portion of the piston so as to allow the passage of the fluid radially through the piston.

According to one embodiment, the piston has a support flange projecting radially outward from the front portion of the piston, the hydraulic control device further comprising a preload spring which is arranged around the annular chamber and is in abutment against the support flange and at least one bore is formed in the support flange so as to allow the passage of the fluid axially through the support flange.

According to one embodiment, the front portion of the piston has a plurality of through bores which allow the passage of the fluid through said piston.

According to one embodiment, the fluid passage network includes an upstream pipe which is connected to the first portion, opens out to the outside of the casing and is intended to be supplied with fluid.

According to one embodiment, the upstream pipe has a radial orientation.

According to one embodiment, the upstream pipe is formed in an upper portion of the casing, intended to be disposed above the X axis. The upstream pipe thus makes it possible to conduct the fluid by gravity or by means of a device ensuring the flow of fluid, such as a pump or an actuator, to the first portion.

According to one embodiment, the piston comprises a support flange projecting radially outward from the front portion of the piston, the hydraulic control device further comprising a preload spring which is disposed in an annular housing formed radially around of the annular chamber and is in abutment against the support flange and said annular housing forms the first portion of the fluid passage network.

According to one embodiment, the at least one bore radially passing through the front portion of the piston is formed in an upper portion of the front portion of the piston which is intended to be disposed above the X axis so as to lead by gravity the fluid from the annular housing formed radially around the annular chamber to an annular space formed radially between the front portion of the piston and the internal tube.

According to one embodiment, the first portion comprises an axial orientation pipe which is formed radially between the annular chamber and the internal tube and opens into an annular space formed radially between the front portion of the piston and the internal tube.

According to one embodiment, the axial orientation pipe is formed in an upper portion of the casing intended to be disposed above the X axis so as to distribute the fluid by gravity in the annular space formed radially between the front portion of the piston and the inner tube.

According to one embodiment, the at least one bore radially passing through the front portion of the piston is formed in a lower portion of the front portion of the piston which is intended to be disposed below the X axis so as to lead by gravity the fluid in the annular space formed radially between the front portion of the piston and the inner tube towards the outside of the front portion of the piston.

According to one embodiment, a radial passage is formed between the front portion of the piston and the internal tube so as to allow the fluid to move axially from the annular space formed radially between the front portion of the piston and the internal tube.

According to one embodiment, the fluid passage network comprises a first portion and a second portion, one of which is formed radially outside the annular chamber and the other of which is formed radially inside the chamber annular.

According to one embodiment, the front portion of the piston carries a rotary stop intended to cooperate with a force transmission member.

According to one embodiment, the rotary stop comprises a ring which is fixed to the front portion of the piston, another ring intended to be in abutment against a force transmission member and rolling bodies, such as needles, arranged between the two rings.

According to one embodiment, the invention also provides a torque transmission system for a motor vehicle comprising:

- a wet clutch comprising an input disc holder and an output disc holder movable in rotation relative to each other about an axis X and a multidisc assembly comprising at least one friction disc integral in rotation one of the input and output disk carriers and at least two plates respectively disposed on either side of said friction disk and integral in rotation with the other of the input and output disk carriers, said multidisc assembly being axially movable between a disengaged position and a engaged position in which the plates pinch the friction disc so as to transmit a torque between the input disc holder and the output disc holder;

- a hydraulic control device mentioned above; and

a force transmission member which bears against the piston of the hydraulic control device and is configured to transmit an actuating force from the piston to the wet clutch so as to move the multidisk assembly between its engaged position and its disengaged position.

According to one embodiment, the torque transmission system comprises a holding element which is integral in rotation with one of the input and output disc carriers and against which the force transmission member is in pivoting support, the torque transmission system further comprising a support bearing which is mounted on the internal tube of the hydraulic control system and which supports the retaining element radially and axially in order to take up the actuating force.

According to one embodiment, the invention also provides a motor vehicle comprising such a torque transmission system.

Brief description of the figures

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely by way of illustration and without limitation. , with reference to the accompanying drawings.

- Figure 1 is an axial sectional view of a torque transmission system.

- Figure 2 is an enlarged view of a portion of the torque transmission system of Figure 1 which is intended to be arranged above the X axis.

- Figure 3 is an enlarged view of a portion of the torque transmission system of Figure 1 which is intended to be arranged below the X axis.

FIG. 4 is a sectional and perspective view of the hydraulic device for controlling the torque transmission system of FIGS. 1 to 3.

Detailed description of embodiments

In the description and the claims, the terms external and internal as well as the axial and radial orientations will be used to designate, according to the definitions given in the description, elements of the torque transmission system. By convention, the radial orientation is directed orthogonally to the axis X of rotation of the torque transmission system determining the axial orientation and, from the inside towards the outside while moving away from said axis. The terms external and internal are used to define the relative position of an element with respect to another, with reference to the axis X of rotation of the torque transmission system, an element close to the axis is thus qualified as internal as opposed to an external element located radially on the periphery. Furthermore, the terms rear AR and front AV are used to define the relative position of one element with respect to another in the axial direction.

In connection with FIG. 1, a torque transmission system 1 is observed, according to one embodiment, for a motor vehicle of the hybrid type and intended to be placed in the traction chain of the motor vehicle between a combustion engine. and a gearbox.

The torque transmission system 1 comprises an input element 2 intended to be coupled in rotation to a crankshaft of a heat engine, not shown. The input element 2 is fixed to the crankshaft by fixing members, such as screws 3.

The torque transmission system 1 also includes an output element 4 intended to transmit the torque to an input shaft of a gearbox, for example by means of a second torque transmission system, not illustrated , such as a torque converter fitted with a lockup clutch or a single or double clutch. The output element 4 comprises internal splines 5 which cooperate with external splines of an output hub 6. The output hub 6 further comprises internal splines intended to cooperate with splines of a drive shaft, not shown, intended to transmit the torque between the output hub 6 and the second torque transmission system.

In the embodiment shown, the output element 4 is coupled to an electric machine, not shown, comprising a rotor whose axis of rotation is parallel to the axis X of rotation of the torque transmission system 1. For to do this, in the embodiment shown, the output element 4 comprises a ring gear 7 which cooperates with a chain 8 which is taken up with the rotor of the electric machine.

The input element 2 and the output element 4 are mounted mobile in rotation about the axis of rotation X by means of a bearing 9 which is interposed between an internal portion of the input element 2 and the outlet hub 6. The bearing 9 is here a rolling bearing.

Furthermore, the torque transmission system 1 comprises a damping device 10 and a wet clutch 11, arranged in the torque transmission path between the input element 2 and the output element 4.

The damping device 10 comprises the input element 2, an intermediate element 12 and elastic members 13 making it possible to transmit the torque and damp the rotational acyclisms between the input element 2 and the intermediate element 12. In the embodiment shown, the elastic members 13 are curved helical springs which are circumferentially distributed around the axis X. Each elastic member 13 is arranged circumferentially between two bearing zones formed on the input element 2 and two support zones formed on the intermediate element 12. In operation, each of the elastic members bears, at one of its ends, against a support zone formed on the input element 2 and, at the 'other of its ends, against a bearing area formed on the intermediate element 12 so as to ensure the transmission of torque between the element input 2 and the intermediate element 12, and that the torque to be transmitted is a driving torque transmitted from the input element 2 to the intermediate element 12 or a resistive torque transmitted from the intermediate element 12 to the element inlet 2. In the embodiment shown, the inlet element 2 comprises an axial orientation skirt 14 which defines an annular housing inside which the elastic members 13 are housed. Furthermore, advantageously , the input element 2 has at its outer periphery, a ring forming an additional mass of inertia 15.

Furthermore, the wet clutch 11 comprises an input disc holder 16 and an output disc holder 17 which are rotatable relative to each other about the axis X. The disc holder input 16 is integral in rotation with the intermediate element 12 of the damping device 10. To do this, in the embodiment shown, the intermediate element 12 is fitted around the input disc carrier 16 and has grooves 18 which cooperate with grooves 19 formed on the external surface of the input disc holder 16. Furthermore, the output disc holder 17 is secured in rotation to the output element 4 by means of a toothing 53.

The wet clutch 11 also comprises a multidisk assembly 20, that is to say an axial stack of friction discs and plates, which is intended to transmit a torque between the input disc holder 16 and the disc holder outlet 17 of said wet clutch 11 when said wet clutch 11 is in its engaged position. The multi-disc assembly 20 comprises a plurality of annular plates, for example of steel, which are integral in rotation with the input disk carrier 16 and mounted to slide axially with respect to said input disk holder 16. To do this, each plate comprises on its external periphery an external toothing which is in engagement with the internal toothing provided on the internal face of the input disc holder 16.

The multi-disc assembly 20 further comprises a plurality of friction discs which are each interposed between two plates and are integral in rotation with the outlet disc holder 17 with freedom of axial translation. To do this, each friction disc has on its internal periphery an internal toothing which is in engagement with the external toothing of the output disc holder 17. Each friction disc has friction linings arranged on each of its faces, before and back.

The multi-disc assembly 20 is supported rearward against a reaction zone 21 formed by a radial orientation portion projecting radially inwards from the input disc holder 16. The wet clutch 11 comprises a plate pressure 22 which is intended to come into abutment against the front face of the multidisc assembly 20. The pressure plate 22 has a support zone 23 projecting axially towards the rear.

Furthermore, the wet clutch 11 comprises a force transmission member 24 which is, on the one hand, bearing against the pressure plate 22 and, on the other hand, bearing against a piston 25 of a hydraulic device command which will be described in detail later. According to one embodiment, the force transmission member 24 is a diaphragm.

The force transmission member 24 is pivotally supported against the intermediate element 12. The intermediate element 12 is supported radially and axially against a support bearing 26 which is mounted on a casing 27 of the torque transmission system 1 so as to resume the actuation efforts. The intermediate element 12 thus forms a holding element for the force transmission member 24. In the embodiment shown, the wet clutch 11 is of the normally closed type, that is to say that, by default , when no actuating force is exerted by the hydraulic control device on the force transmission member 24, the wet clutch 11 is in a engaged state. In another embodiment, the wet clutch 11 is of the normally open type.

Furthermore, the torque transmission system 1 comprises a casing 27 which defines a sealed space in which the wet clutch 11 and the damping device 10 are housed. The casing 27 comprises an internal tube 28 extending axially around the X axis and receiving the support bearing 26. The internal tube 28 extends radially around the internal portion of the input element 2 which is intended to be fixed to the crankshaft of the heat engine. The casing 27 also comprises a rear flange 29 and a front flange 30 of radial orientation which are connected to each other by an external annular portion of axial orientation 31. The rear flange 29 projects radially outwards from the rear end of the inner tube 28.

The housing 27 is sealed by means of a series of seals 32, 33, 34. More particularly, a first seal 32 is disposed radially between the internal portion of the inlet element 2 and the inner tube 28 of the casing 27, a second seal 33 is disposed between the inlet member 2 and the outlet member 4 and a third seal 34 is disposed between the outlet member 4 and the front flange 30 of the casing 27. The first, second and third seals 32, 33, 34 are dynamic lip seals.

The casing 27 is fixed to the internal combustion engine by means of fixing means, not shown. The casing 27 is for example fixed to the motor by means of the rear flange 29 or the external annular portion of axial orientation 31.

The hydraulic control device comprises a body 35 of annular shape which is fitted around the internal tube 28 of the casing 27 and which defines an annular chamber 36. In the embodiment shown, the body 35 is a separate element from the internal tube 28 and of the rear flange 29. The body 35 is for example made of aluminum while the internal tube 28 and the rear flange 29 of the casing 27 are made of steel. The body 35 is fixed to the internal tube 28 and to the rear flange 29. This fixing can in particular be carried out by force fitting the body 35 onto the internal tube 28, by means of fixing members not shown, by gluing or by welding. In another embodiment, not shown, the body 35 providing the annular chamber 36, the internal tube 28 and at least part of the rear flange 29 are formed in one piece.

Furthermore, the hydraulic control device comprises a piston 25 of annular shape which is mounted movable in axial translation inside the annular chamber 36. A channel for supplying pressurized fluid, not shown, is formed in the body. 35 and opens into the annular chamber 36. The pressurized fluid supply channel is connected to a hydraulic circuit equipped with a pump or an actuator. The annular chamber 36 is thus intended to be supplied with fluid so as to cause the piston 25 to move forward from its rest position to its active position.

The piston 25 has a front portion 37 which projects axially beyond the annular chamber 36. In relation to FIGS. 2 and 3, it can be seen that the front portion 37 of the piston 25 carries a rotary stop 38 which is fixed to the 'front end of the front portion 37 of the piston 25. The rotary stop 38 comprises a ring which is fixed to the piston 25, another ring bearing against the force transmission member 24 and rolling bodies interposed between the two rings. According to one embodiment, the rolling bodies are needles which are arranged in a radial orientation, which makes it possible to limit the axial size of the rotary stop 38.

Furthermore, the piston 25 includes a support flange 39 projecting radially outward from the front portion 37 of the piston 25. The body 35 also includes a support flange 40 which projects radially outward from the rear end of the body 35.

The hydraulic control system further comprises a preload spring 41, shown diagrammatically in FIGS. 2 and 3, which has a rear end which is in abutment against the support flange 40 of the body 35 and a front end which is in abutment against the support flange 39 of the piston 25. Thus, the preload spring 41 ensures permanent support of the rotary stop 38 against the force transmission member 24, and in particular against the fingers of the diaphragm.

The preload spring 41 is disposed in an annular housing 42 which is, on the one hand, formed radially around the annular chamber 36, and more precisely formed radially between the body 35 and the output disc carrier 17 of the clutch wet 11 and, on the other hand, axially delimited by the support flange 40 of the body 35 and the support flange 39 of the piston 25.

The torque transmission system 1 also comprises a network for the passage of a lubrication and / or cooling fluid. The fluid is, for example, gearbox oil. The fluid aims to provide cooling and lubrication of the multidisk assembly 20 as well as of the support bearing 26, of the rotary stop 38 and of the articulation of the force transmission member 24 on the intermediate element 12.

The fluid passage network comprises an upstream pipe 43 which is shown in full in FIG. 1 and 4 and partially in FIG. 2. The upstream pipe 43 is formed in the rear flange 29 of the casing 27. More particularly, the upstream pipe 43 is formed in an upper portion of the rear flange 29, that is to say in a portion of said rear flange 29 intended to be disposed above the axis of rotation X, and thus makes it possible to conduct the fluid by gravity or by means of a device ensuring the flow of the fluid, such as a pump or an actuator. The upstream pipe 43 is connected to an inlet pipe 44 which opens to the outside of the casing 27 and which is intended to be supplied with fluid by a pump or by any other device making it possible to collect the fluid and to lead it to the said inlet pipe 44. Note that, in FIGS. 1 and 4, it can be seen that the radial bore defining the upstream pipe 43 opens radially to the outside. This structure results from the machining of the radial bore defining the upstream pipe 43 and the end of the radial bore is intended to be closed by a plug, not shown.

Furthermore, the fluid passage network comprises two portions which are connected to the upstream pipe 43 and which are arranged respectively radially outside and radially inside the annular chamber 36 and make it possible to conduct the fluid from the pipe upstream 43 to the front portion 37 of the piston 25.

One of the two portions is formed by the annular housing 42 in which the preload spring 41 is housed. In order to connect this portion to the upstream pipe 43, the upstream pipe 43 is provided with a bore 45 which opens facing d 'a bore 46 formed in the support flange 40 of the body 35. Taking into account, on the one hand, the annular character of the annular chamber 36 and on the other hand, the arrangement of the upstream pipe 43 above from the X axis, the cooling and / or lubrication fluid is able to diffuse in said annular chamber 36 substantially all around the X axis.

The other of the two portions is formed by an axial orientation pipe 47, illustrated in FIG. 2, which is formed in an upper portion of the casing 27, that is to say disposed above the axis X , radially between the internal tube 28 and the annular chamber 36. The axial orientation pipe 47 is formed opposite a bore 48 formed in the upstream pipe 43 and opens into an annular space 49 formed radially between the front portion 37 of the piston 25 and the inner tube 28. Taking into account, on the one hand, the annular character of the annular space 49 and on the other hand, the arrangement of the upstream pipe 43 above the X axis, the cooling and / or lubrication fluid is able to diffuse in said annular space 49 substantially all around the axis X.

Furthermore, the front portion 37 of the piston 25 is equipped with a plurality of through holes 50, 51, allowing the passage of the cooling and / or lubrication fluid through the piston 25 so as to facilitate the circulation of said fluid in the direction of the multidisk assembly 20, of the rotary stop 38, of the support bearing 26 and / or of the articulation of the force transmission member 24.

In particular, as shown in FIGS. 2 and 4, the support flange 39 has one or more through holes 50 which allow the cooling and / or lubrication fluid to pass through said support flange 39 in order to circulate, from the housing annular 42 towards the rotary stop 38, the articulation of the force transmitting member 24 and the support bearing 26. In one embodiment, as shown in FIG. 4, the holes 50 are regularly distributed around the X axis.

Furthermore, the front portion 37 of the piston 25 also includes one or more holes 51 of radial orientation, illustrated in FIGS. 2 and 4, which allow the cooling and / or lubrication fluid to circulate between the annular housing 42 in which is disposed the preload spring 41 and the annular space 49 formed radially between the front portion 37 of the piston 25 and the internal tube 28. In one embodiment, as shown in FIG. 4, the holes of radial orientation 51 are regularly distributed around the X axis.

When a radial orientation hole 51 is formed in an upper portion of the front portion 37 of the piston 25, that is to say extending above the axis X, said radial orientation hole 51 allows the cooling and / or lubrication fluid to flow, radially inwards, from the annular housing 42 to the annular space 49 while when a bore of radial orientation 51 is formed in a lower portion of the front portion 37 of the piston 25, that is to say extending below the X axis, said radial orientation bore 51 allows the cooling and / or lubrication fluid to flow, radially outward, from the annular space 49 towards annular housing 42.

Furthermore, the front portion 37 of the piston 25 being positioned, over its entire length, radially away from the internal tube 28, the cooling and / or lubrication fluid is able to diffuse in the direction of the support bearing 26 from of the annular space 49.

We further observe that the radially internal disc holder, namely the outlet disc holder 17 in the embodiment shown, is also equipped with through holes 52 passing through in a radial orientation, in particular shown in FIGS. 2 and 3, which allows the fluid to diffuse from the annular housing 42 towards the multidisc assembly 20.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these these are within the scope of the invention.

The use of the verb "comprise", "understand" or "include" and its conjugated forms does not exclude the presence of other elements or steps than those set out in a claim.

In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims (10)

1. Hydraulic control device for controlling a wet clutch (11) comprising an input disc holder (16) and an output disc holder (17) movable in rotation relative to each other around an axis X and a multidisk assembly (20) comprising at least one friction disc integral in rotation with one of the input and output disc carriers and at least two plates respectively arranged on either side of said friction disc and integral in rotation with the other of the input and output disc carriers, said multidisc assembly (20) being axially movable between a disengaged position and a engaged position in which the plates pinch the friction disc of so as to transmit a torque between the input disc holder (16) and the output disc holder (17), the hydraulic control device comprising - a housing (27) comprising an internal tube (28) extending axially around the axis X, said housing (27) comprising an annular chamber (36) formed radially around the internal tube (28); and - an annular piston (25) mounted axially movable in said annular chamber (36) between a engaged position and a disengaged position, said piston (25) having a front portion (37) which projects axially beyond the annular chamber ( 36); in which the casing (27) comprises a network for the passage of a fluid which comprises at least a first portion (42, 47) formed radially outside or inside the annular chamber (36) and arranged to conduct the fluid up to the front portion (37) of the piston (25) and in which said front portion (37) of the piston (25) comprises at least one through hole (50, 51) allowing the passage of the fluid through said piston (25). 2. Hydraulic control device according to claim 1, in which the at least one bore (51) passes radially through the front portion (37) of the piston (25) so as to allow the passage of the fluid radially through the piston (25 ). 3. Hydraulic control device according to claim 1 or 2, wherein the piston (25) comprises a support flange (39) projecting radially outwards from the front portion (37) of the piston (25), the hydraulic control device further comprising a preload spring (41) which is arranged around the annular chamber (36) and bears against the support flange (39) and in which the at least one bore (50) is formed in the support flange (39) so as to allow the passage of the fluid axially through the support flange (39). 4. Hydraulic control device according to any one of claims 1 to 3, wherein the front portion (37) of the piston (25) has a plurality of through holes (50, 51) which allow the passage of the fluid through said piston (25). 5. Hydraulic control device according to any one of claims 1 to 4, in which the fluid passage network comprises an upstream pipe (43) which is connected to the first portion (42, 47), which opens out to the outside of the casing (27) and is intended to be supplied with fluid. 6. Hydraulic control device according to any one of claims 1 to 5, in which the upstream pipe (43) is formed in an upper portion of the casing (27), intended to be disposed above the X axis. 7. Hydraulic control device according to any one of claims 1 to 6, in which the piston (25) comprises a support flange (39) projecting radially outwards from the front portion (37) of the piston ( 25), the hydraulic control device further comprising a preload spring (41) which is arranged in an annular housing (42) formed radially around the annular chamber (36) and is in abutment against the support flange (39 ) and wherein said annular housing (42) forms the first portion of the fluid passage network. 8. Hydraulic control device according to any one of claims 1 to 6, in which the first portion comprises an axial orientation pipe (47) which is formed radially between the annular chamber (36) and the internal tube (28) and opens into an annular space (49) formed radially between the front portion (37) of the piston (25) and the internal tube (28). 9. Hydraulic control device according to any one of claims 1 to 8, in which the fluid passage network comprises a first portion (42) and a second portion (47) one of which is provided radially on the outside. of the annular chamber (36) and the other of which is formed radially inside the annular chamber (36). 10. Torque transmission system (1) for a motor vehicle comprising: - a wet clutch (11) comprising an input disc carrier (16) and an output disc carrier (17) movable in rotation relative to each other about an axis X and a multidisc assembly ( 20) comprising at least one friction disc integral in rotation with one of the input and output disc carriers and at least two plates respectively disposed on either side of said friction disc and integral in rotation with the other of the input and output disk carriers, said multidisc assembly (20) being axially movable between a disengaged position and a engaged position in which the plates pinch the friction disk so as to transmit a torque between the disk carrier d input (16) and the output disc port (17); - a hydraulic control device according to any one of the claims 1 to 9; and - a force transmission member (24) which bears against the piston (25) of the hydraulic control device and is configured to transmit an actuating force from the piston (25) to the wet clutch (11) of so as to move the multidisk assembly (20) between its engaged position and its disengaged position.