Connection unit for quick connection / disconnection of fluid lines

Abstract

The connection unit includes a first connector (2) and a second connector (3) configured to be connected to respective circuit branches of a fluid line, and a coupling element (4) for coupling said connectors (2, 3) together and establishing a fluid connection between the circuit branches, said connectors (2, 3) having a first normally closed sealing element (30) for defining a sealed termination of said circuit branches when the connectors (2, 3) are disconnected from each other, and the coupling element (4) has a dual normally closed sealing element (30) that is separable from the female connectors (2, 3). The system includes a male connector (50), the male connector (50) being a double male connector having a pair of shanks (68) that can be coupled to each of the female connectors (2, 3), and a control element (70) that is movable between a first position in which the coupling element (4) can be coupled to the female connectors (2, 3) in a mechanical pre-coupled state with no fluid connection between them, and a second position in which the shanks (68) of the double male connector (50) engage with each of the female connectors (2, 3) and establish a fluid connection therebetween.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority from European Patent Application No. 20184051.9, filed July 3, 2020, and Italian Patent Application No. 102020000022447, filed September 23, 2020, the disclosures of which are incorporated herein by reference in their entireties.

[0002] The present invention relates to a connection unit for quick connection / disconnection of fluid lines.

[0003] The invention has advantageous, but not exclusive, applications in the space field, in particular for fluid lines in space stations, which will be described below without loss of generality.

[0004] The invention can also be applied in various non-space applications, such as connecting fluid lines in ground installations, aircraft or ships, whenever the problem of connecting circuit branches between themselves under pressure arises. [Background technology]

[0005] The connection between two branches of a fluid line is usually made by a connection unit formed by a male connector and a female connector that can be mated together.

[0006] For example, in space missions, such as those leading to the realization of the International Space Station, the problem of making a fluid connection between two circuit branches, at least one of which is pressurized before being connected, often arises.

[0007] For this purpose, connection units are used in which male and female connectors can form the sealed termination of each circuit branch, the male and female connectors having movable sealing elements therein that are designed to provide a static seal when the connectors are disconnected and to interact with each other to provide fluid continuity between the lines when they are connected.

[0008] While it is relatively simple to create a seal inside a female connector by means of a movable sealing element that can retract when mated with a male connector, creating a movable sealing element inside a male connector is generally more complex and requires expensive technical solutions and high-precision machining.

[0009] Patent document 1 describes a solution in which the male connector consists of a double male connecting element that is permanently coupled to the female connecting element, and when the male connector is inserted into the female connector, a fluid connection is immediately established between the two connectors.

[0010] In known solutions, the connection between the male and female connectors is made by a ring nut that is coaxial with the male connector, and the male connector can be connected to the female connector by a thread connection that requires some rotation of the ring nut to make the connection, which means that the connection cannot be made by a robotic arm. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] British Patent No. 607340 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention therefore aims to provide a connection unit that solves the above problems. [Means for solving the problem]

[0013] According to the present invention, a connection unit is achieved as claimed in the accompanying claims.

[0014] In order that the invention may be better understood, preferred embodiments will now be described, by way of non-limiting example and with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view of a connection unit in an operating position; FIG. [Figure 2] 1 is a perspective view of a connection unit in an operating position; FIG. [Figure 3] 1 is a perspective view of a connection unit in an operating position; FIG. [Figure 4] FIG. 10 is an exploded perspective view of the female connector of the connection unit of the previous figures; [Figure 5] FIG. 4 is an exploded perspective view of a coupling element of the connection unit of FIGS. 1 to 3. [Figure 6] 2 corresponds to the view of FIG. 1 with parts shown transparent for clarity; [Figure 7] 2 is a side and partial cross-sectional view of the connection unit in a position corresponding to the view of FIG. 1, with parts removed for clarity; [Figure 8] 3 is a view corresponding to that of FIG. 2, with parts shown transparent for clarity; [Figure 9] 9 is an axial cross-sectional view of the connection unit of FIGS. 2 and 8 in the operating position; FIG. [Figure 10] 4 is an axial cross-sectional view of the connection unit in the operating position of FIG. 3; FIG. [Figure 11] 11 is a perspective view of the connection unit of FIGS. 3 and 10 in the operating position, with parts transparent for clarity; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will now be described in detail with reference to the accompanying drawings in order to enable those skilled in the art to realize and use the same. Various modifications to the presented embodiments will be readily apparent to those skilled in the art, and the general principles disclosed herein can also be applied to other embodiments and applications without departing from the scope of protection of the present invention as defined in the appended claims. Therefore, the present invention should not be considered as being limited to the embodiments described and shown, but should be accorded the widest scope of protection in accordance with the features described and claimed.

[0017] To facilitate an understanding of the embodiments described herein, reference will be made to certain specific embodiments and specific terminology will be used to describe them. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

[0018] 1 to 3, the number 1 indicates as a whole a connection unit for fluid lines realized according to the invention. Unit 1 is shown in a disconnected configuration (i.e., exploded into its components) in Fig. 1, in a mechanical pre-connected configuration in Fig. 2, and in a mechanically and fluidly connected position in Fig. 3.

[0019] The unit 1 of the axis A essentially comprises a first connector 2, a second connector 3 and a coupling element 4 interposed between the connectors 2 and 3.

[0020] Connectors 2 and 3 are both female and identical to each other. The following description referring to connector 2 therefore also applies to connector 3.

[0021] The connector 2 (which can be seen in more detail in Figure 4 and Figures 8 to 10) comprises a nipple 5 having a cup-shaped body 6 defining a cylindrical cavity 7 therein, axially bounded by a flat annular intermediate wall 8, and a threaded tubular fitting 9 cantilevering axially from the intermediate wall 8 and defining a conduit 10 leading to the cavity 7.

[0022] The threads of the fitting 9 are designed to fluidly connect the connector 2 to a respective branch of a fluid circuit, not shown, which may consist of a device such as a pump, a compressor or equipment of any nature, or a fluid line such as a gas conduit or a pipeline for transporting a liquid such as water, hydraulic oil, gas or general fluids of any nature, including organic matter.

[0023] The cup-shaped body 6 has an external thread 11 designed to allow mechanical connection with a fixed bulkhead (not shown) through which the connector 2 can be attached. The bulkhead may consist of a wall or panel forming part of the device.

[0024] The connector 2 (Figures 4, 9 and 10) further comprises a distributor 14 in the form of a cylindrical disk housed in the cavity 7 of the nipple 5, and a body 15 in axial contact with the distributor 14 and partly housed in the cavity 7. The distributor 14 and the body 15 define a number of flow paths 16 for the fluid, which have complex shapes to minimize pressure losses and are conveniently obtained by additive manufacturing techniques (3D printing). These flow paths 16 can be clearly seen in Figure 11, where the parts of the connection unit 1 are shown transparently.

[0025] More specifically, distributor 14 has a first flat surface 17 arranged in axial contact with intermediate wall 8 and a second flat surface 18 arranged in axial contact with body 15 (Figures 9 and 10). Portion 16a of flow path 16 realized in distributor 14 comprises a central chamber 19 directly facing conduit 10 and a plurality of conduits 20 extending radially from chamber 19 in a radial pattern and axially merging onto second surface 18. Chamber 19 is closed towards second surface 18 (Figure 11).

[0026] The substantially cylindrically shaped body 15 has a first base surface 23 arranged in axial sealing contact with the second surface 18 of the distributor 14, and an opposite second base surface 24.

[0027] The portion 16b of the flow path 16 realized in the body 15 comprises an axially passing conduit 25 and a plurality of conduits 26 which connect axially on the first face 23 of the conduit 20 and extend radially in a radial pattern towards an end zone 27 of the conduit 25 opposite the first face 23, opening into the end zone 27 to form openings 28.

[0028] Conveniently, at the outlet holes of the conduits 20 and 26 on each face 18, 23 of the distributor 14 and body 15, respective annular grooves 29a, 29b are provided, which axially coincide to form an annular channel 29 (Figure 11) that fluidly connects the conduits 20 and 26 to each other.

[0029] A piston 30 is sealingly housed in the conduit 25 and is axially slidable between an advanced position (FIG. 9) in which it occupies an end zone 27 of the conduit 25 and thus closes the outlet opening 28 of the conduit 26, and a retracted position (FIG. 10) adjacent to the distributor 14. The advanced position of the piston 30 is defined by contact between the piston and an inner annular projection 31 at the end of the conduit 25 and is maintained by a spring 21 housed in the conduit 26 between the distributor 14 and the piston 30.

[0030] Finally, the body 15 includes a substantially rectangular flange 32 extending radially from the outer surface of the body near the first face 23. Two coaxial cylindrical pins 33 extend radially on either side of the flange 32.

[0031] Finally, the body 15 has an annular projection 34 extending axially from the outer edge of the second face 24 and defining a cylindrical seat 35 for coupling with the coupling element 4, which will be described below.

[0032] The connector 2 also includes a pre-attached clamp 36 which can be seen in FIGS.

[0033] Clamp 36 includes two jaws 37 hinged about its respective pins 33. Each of jaws 37 includes a pair of blades 38 extending axially on opposite sides of body 15 and having proximal and distal ends 39, 40 hinged to the respective pins 33.

[0034] The blades 38 (FIG. 8) are provided on their facing longitudinal sides with respective leading chamfers 44 that move away towards the distal end 40 and respective axially elongated intermediate recesses 45 that face each other.

[0035] The jaws 37 further comprise respective connecting plates 46 which integrally connect the respective outer intermediate zones of the blades 38 of each jaw to one another and which arc to extend around the body 15 .

[0036] The jaws 37 are loaded by springs 47 (FIG. 8) wrapped around each pin 33 and tending to keep the jaws 37 in a closed position.

[0037] 5 and 8 to 10, the coupling element 4 comprises a double male connector 50 that can be separated from the female connectors 2, 3, a body 51 that surrounds the connector 50, and a pair of pistons 52 that slide within the body 51.

[0038] More specifically, connector 50 comprises an elongated, cylindrically shaped, axial tubular element 62 defining therein a central axial conduit 53 closed at both ends. Near its opposite axial ends, tubular element 62 has a plurality of radial openings 54 ( FIG. 5 ) extending in a radial pattern from and communicating with conduit 53. Openings 54 correspond in number and spatial arrangement to outlet openings 28 of conduits 26 in central conduit 25 of body 15, as will be further described below.

[0039] Connector 50 further comprises an intermediate plate 55 which extends integrally radially from tubular element 62 in a plane perpendicular to axis A and has a substantially rectangular shape (FIG. 5) with two flat sides 56 and two oppositely curved sides 57. Plate 55 divides tubular element 62 into two cylindrical shanks 68, each of which functions as a male connecting element designed to mate with a respective female connector 2, 3.

[0040] Plate 55 includes a plurality of blind radial chambers 59 that are fluidly connected to central conduit 53 by radial passages 60 .

[0041] The body 51 is divided into two substantially cylindrical portions 51a, 51b, each of which has an outer flange 64 and an inner annular projection 65 at its opposite ends (FIG. 10). The flanges 64 rest on opposite faces of a plate 55 and are secured to one another by a number of screws 66 (FIGS. 9 and 10) passing through the plate 55, thus forming the body 51. The body 51 defines a pair of annular chambers 67, located on either axial side of the plate 55, by means of tubular elements 62. A piston 52 is sealingly and slidably received within each chamber 67 and has an annular end projection 69 at one end opposite the plate 55, designed to cooperate with each body 15 by being sealingly received in a corresponding cylindrical seat 35 of the body. The piston 52 is normally held in contact with the inner annular projection 65 of the body 51 by a respective spring 63 housed in the annular chamber 67.

[0042] Extending radially outwardly from flange 64 of each half 51a, 51b of body 51 are two radially opposed rungs 58, the function of which will become apparent below.

[0043] All sliding seals are realized by sealing rings, and the sliding seals are preferably redundant, i.e., comprise two sealing rings in succession along each possible leakage path. A detailed description of the sealing rings and their location is considered redundant, as it is within the scope of a person skilled in the art.

[0044] Finally, the coupling element 4 comprises an outer annular ring 70, coaxial with the body 50, and formed by two parts 70a, 70b surrounding the plate 55, which, after being coupled together (FIG. 7), is rotatably housed in an internal groove 71 formed by the two parts 70a, 70b. The ring 70 has two diametrically opposed projections 72, each of which extends axially on either side and defines on its outer surface a substantially elongated rectangular area 73 on which an identification mark can be printed or fixed in any manner, as will be further described below.

[0045] The ring nut 70, which can be seen in particular from Figures 5 and 7 (wherein all parts of the coupling element 4 are omitted for clarity), has a ramp-like groove 74 therein designed to cooperate with each rung 75 carried by the jaws 37 of the clamp 36 so as to form a bayonet coupling between the coupling element 4 and each of the connectors 2, 3, respectively.

[0046] More specifically, rungs 75 extend radially from and in diametrically opposed positions between each jaw 37 of clamp 36 of each connector 2, 3 when clamp 36 is in a closed position, as will be further described below.

[0047] The inner grooves 74 of the ring nut 70 (only two of which are visible in Figure 7) extend circumferentially at 90° and have circumferential inlet openings 76 located on the sides of each projection 71 and near the front face 77 of the ring nut, ramp-like portions 78 extend towards the centre of the ring nut 70, and substantially circumferential blank end portions 79 with ends 79a define slight recesses turned axially towards each connector 5.

[0048] Finally, the connection unit 1 includes a keying system 80 designed to prevent incorrect coupling between connectors belonging to different fluid lines. The keying system 80, which can be seen in detail in Figures 4 to 6, consists of a pair of keys 81 carried by each female connector 2, 3 and a pair of keys 82 carried by the coupling element 4, the keys 82 being designed to axially mate with each key 81 when coupling between the connectors 2, 3 and the coupling element 4.

[0049] The keys 81, 82 are interchangeable and uniquely identify the pipeline to which the connection unit belongs; in other words, the keys 81, 82 constitute a "code" associated with a particular pipeline.

[0050] 6, the key 81 may be in the form of a plate mounted to be coupled within the connecting plate 46 of the jaw 37, while the key 82 may comprise a base 83 designed to be fixed at its front surface onto each flange 64 of the body 51 of the coupling element 4, with a number of axial projections 84 extending cantilever-like from the base 83. The projections 84 and the key 81 have complementary shapes to allow a sliding axial coupling.

[0051] Conveniently, at least one of the keys 81 of each connector 2, 3 has a radially outer projection 85 terminating in an axially folded appendage 86, the function of which will be made clear below.

[0052] The operation of the connection unit 1 is as follows.

[0053] 1, 6 and 7 the unit is shown in the disconnected position, with both connectors 2, 3 separated from the coupling element 4. In FIG.

[0054] In this state, the connectors 2, 3 seal off each branch of the fluid circuit: in fact, the spring 21 holds the piston 30 in the end-of-stroke position shown in Figure 9, in which the piston 30 occupies the end zone 27 of each conduit 25 and closes the outlet opening 28 of the conduit 26.

[0055] By moving the connectors 2, 3, which are properly aligned axially and circumferentially with respect to one another, axially closer towards the coupling element 4, the keys 81, 82 interact with one another. If the connection is incorrect, i.e., if the keys 81, 82 do not match, the connection is prevented by a frontal collision between the keys. This collision generates a torque on the jaws 37 about the pin 33 in a direction that opens the jaws, thus preventing any further axial proximity between the connectors 2, 3 and the coupling element 4 and making the connection impossible.

[0056] If the connection is correct, i.e., if the keys 81, 82 match, the keys 81, 82 can penetrate each other axially and continue the coupling stroke until the jaws 37 of the clamps 36 of the connectors 2, 3 contact the respective rungs 58 of the coupling element 4. The rungs 58 are forced between the chamfers 44 of the blades 38, opening them against the action of the springs 47. When the rungs 58 engage the recesses 45, the jaws 37 are held close together by the compression of the springs 47, resulting in a mechanical pre-coupling between the connectors 2, 3 and the coupling element 4 (FIGS. 2, 8, and 9).

[0057] It should be noted that the recess 45 is axially elongated to allow further axial approximation between the connectors 2, 3 and the coupling element 4 from the pre-coupled state.

[0058] It should also be noted that this state results in a mechanical connection, not a fluid connection. Indeed, with particular reference to Figure 9, in this mechanical pre-coupled state, the body 15 of the connectors 2, 3 comes into axial contact with the piston 52 of the coupling element 4, its projections 34 engaging the respective seats 35, but the piston 52 remains in an end-of-stroke position in contact with the projections 65, and therefore the opening 54 remains closed. Furthermore, the piston 30 of the connectors 2, 3 is in axial contact with both ends of the tubular element 62, but remains in the end zone 27 of the conduit 29, and therefore the opening 28 remains closed.

[0059] To achieve a fluid seal, the ring nut 70 must be rotated 90° from the position shown in FIG. 2 to that shown in FIG.

[0060] 2, in the pre-coupled position, the rungs 75 of the jaws 37 of the connectors 2, 3 face circumferentially toward the entrance openings 76 of the ramped grooves 74 of the coupling element 4. By turning the ring nut 70, the rungs 75 enter each groove 74 and move through the grooves until they reach their blocked ends 79a. Due to the ramped shape of the grooves 74, doing so causes an axial displacement of the connectors 2, 3 toward the inside of the coupling element 4.

[0061] 10, the end of the tubular element 62 penetrates axially inside the central conduit 25 of the body 15 of the connector 2, 3, displacing the piston 30 axially against the action of the spring 21. The piston 30 thus opens the opening 28.

[0062] At the same time, the piston 52 of the coupling element 4 retracts towards the plate 55 in each chamber 67, against the action of the spring 53, due to axial contact with the body 15 of the connectors 2, 3. In this way, the piston 52 opens the opening 54 located in the opening 28. A connection is therefore established between the conduits 26 of the connectors 2, 3 and the central conduit 53 of the tubular element 52, as can be clearly seen from Figure 11, where these conduits are highlighted.

[0063] After the units have been connected, the projection 71 of the ring nut 70 is aligned with the attachment 86 of the key 81, providing visual confirmation that the connection has been completed. If automatic handling of the units is anticipated, a code, such as a barcode for example, can be fixed partly to the projection 71 and partly to the associated 86. In this way, it is only possible to complete and read the code after a successful connection.

[0064] In the above description, the unit is shown, for the sake of clarity, as being formed by three elements (connectors 2, 3 and coupling element 4) that are initially disconnected and separated from one another. In practice, in use, it is convenient for coupling element 4 to be pre-attached to one of the two female connectors 2, 3, i.e., to be mechanically connected to this connector in the stated pre-coupled position. The connection of unit 1 therefore comprises the connection of two sub-units, one constituted by the pairing of a first connector (e.g., connector 2) and coupling element 4, and the other constituted by the second connector 3. This connection therefore comprises an initial pre-coupling step of connector 3 and a fluid connection step by rotating ring nut 70.

[0065] The advantages obtained become clear when examining the properties of the connection unit 1 realized according to the invention.

[0066] First, the use of two female connectors 2, 3 designed to connect to each circuit branch, and the use of a dual male coupling element that is not in fluid communication with either of said branches prior to connection, can greatly simplify the construction while reliably achieving a seal for the two circuit branches prior to connection, resulting in a low overall cost and high reliability of the connection unit.

[0067] Another advantage of the units is the simplicity of the movement required to connect, which involves a slight rotation in the example shown of 90°, so that connection of the units can be easily achieved using an automatic manipulator.

[0068] A further advantage is that if the keys on the connector and coupling element do not match, connection is prohibited.

[0069] The indication of alignment between one of the projections 71 of the ring nut 70 and the attachment 86 of the key 81, and the possibility of this alignment forming a machine-readable code, provides further assurance of the reliability of the connection.

[0070] Finally, the presence of a compensation volume (consisting for example of the chamber 59 in plate 55) secondary connected to the fluid paths in the unit allows at least partial absorption of pressure waves (water hammer) that may occur due to the sudden connection of circuit branches subjected to different pressures.

[0071] Finally, it is clear that modifications and variations can be made to the described unit 1 without going beyond the scope of protection defined by the claims.

[0072] In particular, the bayonet coupling between the coupling element 4 and the connectors 2, 3 can be replaced by another type of mechanism, in order to achieve connection by a robotic arm, if the transition from the pre-coupled state to the fluid connection state can be achieved by a simple movement of the control element, for example by a slight rotation or by a translation.

[0073] The ring nut 70 can therefore be replaced by a different type of control element, such as, for example, a lever.

[0074] The specific implementation of the sealing elements included in the connectors 2, 3 and the coupling element 4 may vary.

[0075] The chamber 59 may be replaced by or integrated with a compensation volume located in other parts of the connection unit, for example in the connectors 2,3. [Explanation of symbols]

[0076] 1 Connection Unit 2 First Connector 3 Second Connector 4. Bonding Elements 5 nipples 6 Main unit 7 Cavity 8 Intermediate Wall 9 Tubular Fittings 10 Conduit 11 threads 14 Distributor 15 Main Unit 16 Flow path 16a Flow path section 16b Flow path section 17 First Flat Surface 18 Second Flat Surface 19 Central Chamber 20 First Conduit 21 Spring 23 First base surface 24 Second base surface 25 Second Conduit 26 Conduit 27 Edge Zone 28 Opening 29 Annular Channel 29a Annular groove 29b Annular groove 30 pistons 31 Annular protrusion 32 flange 33 pin 34 Protrusion 35 Seat area 36 Clamp 37 Chin 38 Blades 39 Proximal end 40 distal end 44 Chamfered part 45 recess 46 Connecting plate 47 Spring 50 double male connector 51 Main unit 51a Cylindrical part 51b Cylindrical part 52 Piston 53 Conduit 54 Radial opening 55 Intermediate plate 56 Flat Side 57 Curved Side 58 Lang 59 Chamber 60 Radial Passage 62 Tubular elements 63 Spring 64 Outer flange 65 Inner annular protrusion 66 Screw 67 Annular Chamber 68 Shank 69 End protrusion 70 Annular ring, ring nut 70a part 70b part 71 Internal groove 72 Protrusion 73 Rectangular area 74 Groove 75 Lang 76 Inlet opening 77 Front 78 Ramp-like section 79 Blind Edge 79a End 80 key system 81 keys 82 keys 83 Base 84 Axial protrusion 85 Radial outer protrusion 86 Accessory

Claims

1. 1. A connection unit comprising: a first connector (2) and a second connector (3) configured to be connected to respective circuit branches of a fluid line; and a coupling element (4) for coupling said first connector (2) and said second connector (3) together and establishing a fluid connection between said circuit branches, said first connector (2) and said second connector (3) comprising a first normally closed sealing element (30) for defining a sealed termination of said circuit branches when said first connector (2) and said second connector (3) are disconnected from each other; the first connector and the second connector are both female connectors (2, 3); The coupling element (4) includes a double male connector (50) separable from the female connectors (2, 3), the double male connector (50) having a pair of shanks (68) that can be coupled to each of the female connectors (2, 3), and a control element (70) that is movable between a first position in which the coupling element (4) can be coupled to the first connector (2) and the second connector (3) in a mechanical pre-coupled state with no fluid connection between the female connectors (2, 3), and a second position in which the shanks (68) of the double male connector (50) engage with each of the female connectors (2, 3) and establish a fluid connection between the double male connector (50) and each of the female connectors (2, 3). A connection unit comprising:

2. 2. The connection unit of claim 1, further comprising a mechanism configured to axially move the first connector (2) and the second connector (3) closer to the coupling element (4) in response to movement of the control element (70) between the first position and the second position.

3. A connection unit as described in claim 2, wherein the control element is a ring nut (70) and the mechanism is a bayonet coupling (74, 75).

4. 4. A connection unit according to any one of claims 1 to 3, wherein the movement of the control element (70) from the first position to the second position is a rotation of a magnitude equivalent to a slight turn.

5. 2. The connection unit of claim 1, wherein the first connector and the second connector include nipples for connecting to each of the circuit branches and for defining a first conduit (10) in fluid communication with each of the circuit branches in use and a second conduit (25) that can be engaged by each of the shanks (68) of the double male connector (50), the first conduit (10) and the second conduit (25) being connected by at least one channel (20, 26) leading to the second conduit (25) through at least one radial opening (28), and a first sealing element of the female connector (2, 3) includes a piston (30) slidably received within the second conduit and capable of moving in response to a depression of each of the shanks (68) to open the at least one radial opening (28).

6. 6. The connection unit of claim 5, wherein the shank (68) of the double male connector (50) is closed at its end and has at least one radial opening (54) designed to fit into the at least one radial opening (28) of each of the female connectors (2, 3).

7. 7. The connection unit of claim 6, wherein the coupling element (4) includes a second sealing element (52) that is slidable on each of the shanks (68) and selectively sealingly cooperates with the at least one radial opening (54), the second sealing element (52) being movable when it contacts each of the female connectors (2, 3) and opening the at least one radial opening (54) when the shank (68) engages with each of the second conduits (25).

8. 2. The connection unit of claim 1, wherein the first and second connectors and the coupling element include respective keys (81, 82) corresponding to a given fluid line, the keys (81, 82) being configured to prevent coupling between the first and second connectors (2) and the coupling element (4) when a connection of circuit branches belonging to different fluid lines is made.

9. 2. The connection unit according to claim 1, wherein the mechanical pre-coupling position is defined by an elastic coupling between a clamp (36) carried by one of the first connector (2) and the second connector (3) and at least one rung carried by the coupling element (4), or between at least one rung carried by one of the first connector (2) and the second connector (3) and a clamp carried by the coupling element (4).

10. A connection unit as described in claim 9, wherein the first connector and the second connector and the coupling element include respective keys (81, 82) corresponding to a given fluid line, the keys (81, 82) being configured to prevent coupling between the first connector (2) and the second connector (3) and the coupling element (4) when connection of circuit branches belonging to different fluid lines is made, and the keys (81, 82) being configured to prevent the clamp (36) from closing in the event of an incorrect connection.

11. 2. The connection unit according to claim 1, wherein at least one of the first connector (2), the second connector (3) and the coupling element (4) comprises at least one compensation volume (59).

12. 4. The connection unit of claim 3, wherein the first connector (2), the second connector (3) and the ring nut (70) have respective visual indicia (86, 71) aligned with each other at the second position of the ring nut (70).

13. 13. A connection unit as claimed in claim 12, wherein said visual indicia (86, 71) together define an automatically readable code.

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