Fluid line coupling device

Abstract

Fluid Conduit Coupling Device The invention relates mainly to a coupling device comprising a male fitting (1) and a female fitting (1'), each fitting comprising a valve (7, 7') equipped with a valve head (8, 8'). The first triggering force FDM for the displacement of the valve head (8) of the male fitting (1) is greater than the second triggering force FD F for the displacement of the valve head (8') of the female fitting (1'), such that the valve head (8') of the second female fitting (1') moves to its clear position before the valve head (8) of the male fitting (1). The force exerted by the second actuation means (9') on the valve head (8) of the male fitting (1) is greater than the first triggering force FDM when the coupling device is in its fluid passage position. Figure to be published with the abbreviation: Figure 1

Description

Title of the invention: Fluid conduit coupling device TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of fluid conduit coupling devices, and more particularly of cryogenic fluid. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Coupling devices are known to transfer fluids, including cryogenic fluids, from a storage tank to a mobile use tank.

[0003] To achieve this, the coupling device comprises a first male fitting and a second female fitting, which are poppet valves whose ends are butted together. Each valve has a fluid passage orifice from which a poppet protrudes, supported by a spring. In the rest position, the spring keeps the poppets engaged in their respective fluid passage orifices, the fitting thus being in the closed position. Coupling the fittings causes the springs, and therefore the poppets, to move. Under the effect of the coupling, the movement of the poppets creates a passage orifice, ensuring the transfer of fluid through the coupling device.

[0004] The first male fitting is integral with the storage tank while the second female fitting is integral with the mobile use tank to be filled.

[0005] During the opening sequence of the conduit device, in which the device as a whole moves from a position where both male and female fittings are closed to a position where both male and female fittings are open, there is a risk that the valve of the first male fitting will open before the valve of the second female fitting. The cryogenic fluid would then escape into the space between the free ends of the first and second fittings, and the gasification of the fluid would generate an overpressure that could damage the fittings of the conduit device.

[0006] In this context, the invention aims at a fluid coupling device which overcomes the aforementioned disadvantages by providing a connecting pipe preventing any fluid leakage during the opening sequence of the pipe device. Summary of the invention

[0007] To this end, the invention relates to a fluid conduit coupling device comprising a first fitting forming a male part and a second cooperating fitting forming a female part, the first fitting forming the male part comprising: • a longitudinal body that extends along a principal axis from a junction end to a pipe to a coupling end second cooperating fitting of the coupling device, which coupling end has a fluid passage orifice in fluidic communication with a flow channel formed in the longitudinal body and extending from the coupling end to the junction end, • a valve disposed in the flow channel of the longitudinal body, the main axis of which extends along the main axis of the longitudinal body of the first fitting, and which comprises a valve head located at the passage orifice of the coupling end of the longitudinal body and movable longitudinally in the flow channel between a clear position in which the passage orifice is open and a closed, watertight position in which the passage orifice is sealed by a watertight contact between the valve head and a valve head seat provided in the longitudinal body and in the internal extension of the passage orifice, a free sealing end of the valve extending into the passage orifice and projecting from the coupling end, which valve further comprises first means for returning the valve head to its closed, watertight position, the second fitting forming a female part comprising: • a longitudinal body extending from a junction end to a second pipe to a coupling end that surrounds the coupling end of the first fitting, which coupling end has a fluid passage orifice in fluidic communication with a flow channel formed in the longitudinal body and extending from the coupling end to the junction end, • a valve disposed in the flow channel of the longitudinal body and comprising a valve head located at the passage orifice of the coupling end of the longitudinal body, and which is movable longitudinally in the flow channel from a clear position in which the passage orifice is open, to a tight-fitting position in which the passage orifice is closed by a tight-fitting contact between the valve head and a valve head seat provided in the longitudinal body and in the extension of the passage orifice, which valve further comprises second means for returning the valve head to its closed tight-fitting position, The coupling device is actuable between a closed position in which the valve heads of the valves of the first and second fittings are in their sealed position and their free ends are touching, and a fluid flow position from the first male fitting to the second female fitting in which the first return means of the valve head of the first valve are male fitting exert a force on the free end of the valve of the female fitting and maintain the valve head of said valve of the second female fitting in its open position, and the second return means of the valve head of the valve of the second female fitting exert a force on the free end of the valve of the first male fitting and maintain the valve head of said valve of the first male fitting in its open position, which valve head of the valve of the first male fitting is movable from its tight-fitting position to its open position against the first return means when the forces exerted on the free end of said valve are greater than a first triggering force FDM dependent on the first return means,which valve head of the valve of the second female fitting is movable from its sealed position to its uncovered position against the second return means when the forces exerted on the free end of said valve are greater than a second triggering force Fdf dependent on the second return means, which first triggering force FDM of the displacement of the valve head of the valve of the first male fitting is greater than the second triggering force Fdf of the displacement of the valve head of the valve of the second female fitting, and which force exerted by the second actuating means on the valve head of the valve of the first male fitting is greater than the first triggering force FDM when the coupling device is in its fluid passage position,so that the valve head of the second female fitting moves to its clear position before the valve head of the first male fitting when the coupling device moves from its closed position to its fluid passage position from the first male fitting to the second female fitting.

[0008] The invention may also include the following optional features considered individually or in all possible technical combinations: • The coupling ends of the longitudinal bodies of the first and second fittings are in contact support when the coupling device is in its fluid passage position from the first male fitting to the second female fitting. The first means of return are formed of a first spring having the first triggering force FDM and a stiffness kM, and in that the second means of return are formed of a second spring having the second triggering force Fdf and a stiffness kF. The spring constant kM of the first spring is expressed according to the formula [Math 1]: kM — kp x F1\FDF+ i0) with F2 the force exerted against the two valve heads of the male and female fittings when the coupling device is in its fluid passage position, and b the distance between the coupling ends of the longitudinal bodies of the first and second fittings when the coupling device is in its closing position.

[0009] Another aspect of the invention relates to a method for coupling a coupling device according to any one of the preceding claims, characterized in that it comprises the following successive steps: • With the coupling device in its closed position and the valve heads of the valves of the first male fitting and the second female fitting in their closed, watertight position, a progressive force is applied to bring the two male and female fittings together; • Progressive movement of the valve head of the second female fitting towards its clear position as soon as the approach force exerted on the end of said valve of the second female fitting exceeds the value of the second triggering force Fdf, the valve head of the valve of the first male fitting remaining in its closed position of watertight grip; • Progressive movement of the valve head of the first male fitting towards its clear position as soon as the closing force exerted on the end of said valve of the first male fitting exceeds the first FDM triggering force, the valve head of the second female fitting being in its clear position; • Arrival of the valve head of the first male fitting in its clear position and of the coupling device in its fluid passage position.

[0010] The process of the invention may also include the following optional features considered individually or according to all possible technical combinations: • The coupling device arrives in its clear position as soon as the coupling ends of the longitudinal bodies of the first and second fittings come into contact.

[0011] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0012] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying figures, which illustrate:

[0013] [Fig.1] Fig.1 is a schematic longitudinal sectional representation of the fluid conduit coupling device of the invention when the fluid passage orifices of the first and second fittings are simultaneously closed;

[0014] [Fig.2] The [Fig.2] is a schematic longitudinal cross-sectional representation of the fluid connection zone of the fluid conduit coupling device of the invention when the fluid passage orifices of the first and second fittings are simultaneously closed;

[0015] [Fig.3] The [Fig.3] is a schematic longitudinal sectional representation of the fluid connection area of ​​the fluid conduit coupling device of the invention when the passage orifice of the first fitting is closed and the passage orifice of the second fitting is clear;

[0016] [Fig.4] The [Fig.4] is a schematic longitudinal cross-sectional representation of the fluid connection zone of the fluid conduit coupling device of the invention when the fluid passage orifices of the first and second fittings are simultaneously cleared, the first fitting being at a distance from the second fitting;

[0017] [Fig.5] The [Fig.5] is a schematic longitudinal cross-sectional representation of the fluid connection zone of the fluid conduit coupling device of the invention when the fluid passage orifices of the first and second fittings are simultaneously cleared, the first fitting coming into contact with the second fitting; DETAILED DESCRIPTION

[0018] It is first specified that in the figures, the same references designate the same elements regardless of the figure in which they appear and regardless of the form of representation of these elements. Similarly, if elements are not specifically referenced in one of the figures, their references can easily be found by referring to another figure.

[0019] It is also specified that the figures represent one embodiment of the invention but that there may be other embodiments which meet the definition of the invention.

[0020] The present invention relates mainly to a fluid conduit coupling device, and in particular a coupling device having a coupling sequence that eliminates - or at least greatly limits - the risk of fluid leakage during the transfer of fluid from a full container to an empty container.

[0021] With reference to [Fig. 1], the coupling device comprises a first male fitting and a second female fitting. The first male fitting is connected to a pipe leading into a reservoir of a container filled with fluid—in particular, a cryogenic fluid—while the second female fitting is connected to a 3' pipe opening into a reservoir of an empty container, designed to collect the cryogenic fluid transferred from the full reservoir.

[0022] With reference to [Fig.1], the male fitting 1 comprises a longitudinal body 2 which extends from a junction end to the pipe 3 connected to the full container (the pipe and the container are not shown) to a coupling end 4 to the second cooperating female fitting 1' of the coupling device, which coupling end 4 has a fluid passage orifice 5 in fluidic communication with a flow channel 6 provided in the longitudinal body 2 and which extends inside the longitudinal body 2 from the coupling end 4 to the junction end 3.

[0023] The male fitting 1 further comprises a valve 7 which is disposed in the flow channel 6 of the longitudinal body 2 on the coupling end side. The main axis XX' of the valve 7 extends along the main axis XX' of the longitudinal body 2. The valve 7 comprises a valve head 8 which is located at the passage orifice 5 of the coupling end 4 of the longitudinal body 2. The valve head 8 extends longitudinally between a free end 11 and a junction base 15 with a longitudinal stem 17, which stem 17 extends in a tubular guide 18 of the fitting 1 forming a longitudinal guide means for the stem 17 in the fitting 1.

[0024] The valve head 8 is displaceable longitudinally in the male fitting 1 and more particularly in the flow channel 6 towards its position of closing the passage orifice 5, by the application of a longitudinal force on said valve head 8 by first return means 9, here a helical spring 9 surrounding the tubular guide 18 and extending longitudinally to the junction base 15 of the valve head 8. This spring 9 is characterized by a stiffness constant kM.

[0025] When no external force is applied to the valve head 8, the compressed spring 9 exerts a restoring force against the base 15 of the valve head 8, driving the valve head 8 into the passage orifice 5 in the sealed position, in which the passage orifice 5 is closed by a sealed contact between the valve head 8 and a frustoconical valve head seat 10 provided in the longitudinal body 2 and in the internal extension of the passage orifice 5. In this position, the free end 11 of the valve head 8 extends into the passage orifice 5, protruding from the coupling end 4.

[0026] The valve 8 is also movable longitudinally within the fitting 1, and more particularly within the flow channel 6, to a position cleared by the action of a longitudinal force exerted from outside the fitting 1 on the free end 11 of the valve head 8, which compresses the spring 9 and opens the fluid passage orifice 5. In particular, a minimum force, referred to as the trigger force FDM, must be applied to the free end 11 of the valve head 8. of the valve 7 of the first male fitting 1 in order to trigger the movement of the valve head 8 from its sealed gripping position to its clear position.

[0027] The second female fitting 1' of the fluid line coupling device has a longitudinal body 2' which extends from a junction end to the second line 3' connected to the empty container intended to collect the fluid contained in the full container (the second line and the empty container are not shown) to a coupling end 4' which surrounds the coupling end 4 of the male fitting 1 by having a recess for the coupling end 4 having a bottom 19' opposite the coupling end 4 of the male fitting 1. As with the male fitting 1, the coupling end 4' has a liquid passage 5' in fluidic communication with a flow channel 6' provided in the longitudinal body 2' and which extends from the coupling end 4' to the junction end 3'.

[0028] The female fitting 1' includes a valve 7' which is disposed in the flow channel 6' of the longitudinal body 2' and which includes a valve head 8' located at the passage orifice 5' of the coupling end 4' of the longitudinal body 2', and which is movable longitudinally in the flow channel 6' between a clear position in which the passage orifice 5' is open, and a closed, watertight grip position in which the passage orifice 5' is closed by watertight contact between the valve head 8' and the frustoconical valve head seat 10' via a sealing gasket 18'.

[0029] As with the first male fitting 1, the valve head 8' of the female fitting 1' is movable longitudinally within the fitting 1', and more particularly within the flow channel 6', towards its position of closing the passage orifice 5', by the application of a longitudinal force on said valve head 8' by secondary return means 9', here a helical spring surrounding the valve stem 7' and extending longitudinally to the valve head 8'. This spring 9' is characterized by a spring constant kF.

[0030] When no external force is applied to the valve head 8', the compressed spring 9' exerts a restoring force against the base 15' of the valve 8', driving the valve head 8' into the passage orifice 5' in a sealed position in which the passage orifice 5' is closed. In this position, the free end 11' of the valve head 8' extends into the passage orifice 5', protruding from the coupling end 4'.

[0031] The valve head 8' is also movable longitudinally in the fitting 1', and more particularly in the flow channel 6', towards a position cleared by the action of a force exerted from outside the fitting 1' on the free end 11' of the valve head 8' which causes the spring 9' to compress and open of the fluid passage orifice 5'. In particular, a minimum force called the trigger force FD F must be applied to the free end 11' of the valve head 8' of the valve 7' of the second female fitting 1' in order to trigger the movement of the valve head 8' from its tight-fitting position to its clear position.

[0032] The coupling device can be actuated between a closing position preventing the circulation of fluid between the two containers, and a fluid passage position between the two containers.

[0033] In the closed position ([Fig.2]) of the coupling device, the valve heads 8, 8' of the valves 7, 7' of the first and second fittings 1, 1' are in their sealing position. Furthermore, the free end 11 of the valve head 8 of the valve 7 of the first male fitting 1 is in contact with the free end 11' of the valve head 8' of the valve 7' of the second female fitting 1'. In other words, the free ends 11, 11' of the two valve heads 8, 8' are in contact without any force being exerted by the first spring 9 on the valve head 8' of the valve 7' of the second female fitting 1', nor by the second spring 9' on the valve head 8 of the valve 7 of the first male fitting 1. Furthermore, in this position of the coupling device, the distance separating the coupling end 4 of the longitudinal body 2 of the first male fitting 1 from the bottom 19' of the housing recess of the coupling end 4' of the female fitting 1' is maximum, and equal to a value b ([Fig.2]).

[0034] In the fluid flow position from the first male fitting 1 to the second female fitting 1' ([Fig. 5]), the first spring 9 of the valve head 8 of the valve 7 of the first male fitting 1 exerts a first force on the free end 11' of the valve head 8' of the valve 7' of the female fitting 1' and holds the valve head 8' of said valve 7' of the second female fitting 1' in its open position. Simultaneously, the second spring 9' of the valve head 8' of the valve 7' of the second female fitting 1' exerts a second force on the free end 11 of the valve 7 of the first male fitting 1 and holds the valve head 8 of said valve 7 of the first male fitting 1 in its open position.

[0035] Thus, the valve head 8 of the valve 7 of the first male fitting 1 is movable from its sealed position to its unsealed position against the first spring 9 when the forces exerted on the free end 11 of said valve 7 are greater than the first triggering force FDM dependent on the first spring 9. In the same way, the valve head 8' of the valve 7' of the second female fitting 1' is movable from its sealed position to its unsealed position against the second spring 9' when the forces exerted on the free end 11' of said valve 7' are greater than the second triggering force Fdf dependent on the second spring 9'.

[0036] According to the invention, when the coupling device is in its fluid passage position, the force exerted by the second spring 9' on the valve head 8 of the valve 7 The force of the first male fitting 1 is greater than the first FDM triggering force. This ensures that, when the coupling device is in its fluid passage position, the two valve heads 8, 8' of the valves 7, 7' of the first and second fittings 1,1' are indeed in their clear position, effectively ensuring the passage of fluid between the two male fittings 1 and female fittings 1', from the full tank to the empty tank.

[0037] For this purpose, the first triggering force FDM of the displacement of the valve head 8 of the valve 7 of the first male fitting 1 is greater than the second triggering force Fdf of the displacement of the valve head 8' of the valve 7' of the second female fitting 1'. Thus, during the coupling of the first and second fittings 1, 1' of the coupling device, the valve head 8' of the valve 7' of the second female fitting 1' moves before the valve head 8 of the valve 7 of the first male fitting 1. Therefore, at the moment of the valve head's movement on the valve of the first male fitting, the distance between the coupling end 4 of the longitudinal body 2 of the first fitting 1 and the bottom 19' of the recess housing the coupling end 4' of the female fitting 1' will be less than the value b, effectively reducing the volume of said recess compared to its initial volume when the coupling device is in its closed position and the respective valve heads 8, 8' are in contact without support. This results in limited fluid leakage into the recess, and consequently a reduced risk of overpressure in the recess. Advantageously, the valve head 8 of the valve 7 of the first male fitting 1 is in its final, unobstructed position when the coupling end 4 of the longitudinal body 2 of the first fitting 1 is in contact with the bottom 19' of the recess for the coupling end 4' of the female fitting 1'. To achieve this, the spring constant kM of the first spring (9) is expressed according to the formula [Math 1]: > - Formula 1 TV kM -Kf* kpb^F^^ where F2 is the force exerted against the two valve heads 8, 8' of the valves 7, 7' of the male fittings 1 and female fitting 1' when the coupling device is in its fluid passage position.

[0038] Thus, the fluid leakage in the recess between the two male 1 and female 1' fittings during the coupling sequence of the coupling device is minimal, or even non-existent, and the risk of overpressure is reduced to a minimum.

[0039] According to the invention and with reference to figures 2 to 5, the coupling sequence of the coupling device will now be described.

[0040] With reference to [Fig. 2], the coupling device is in its closed position: the valve heads 8,8' of the valves 7,7' of the first male fitting 1 and the second female fitting 1' are in their closed, leak-proof position. During the first step of the sequence, a progressive force is applied to bring the two male and female fittings 1,1' closer together.

[0041] As soon as the approach force exerted on the end 11' of the valve head 8' of the valve 7' of the second female fitting 1' exceeds the value of the second triggering force Fdf and as illustrated in [Fig.3] which represents the second step of the sequence, there is a progressive displacement of the valve head 8' of the valve 7' of the second female fitting 1' towards its cleared position, the valve head 8 of the valve 7 of the first male fitting 1 remaining in its closed position of watertight grip.

[0042] As soon as the closing force exerted on the end 11 of the valve 7 of the first male fitting 1 exceeds the first triggering force FDM, and as illustrated in [Fig. 4], which represents the third step of the sequence, a progressive movement of the valve head 8 of the valve 7 of the first male fitting 1 occurs towards its open position. Naturally, the valve head 8' of the valve 7' of the second female fitting 1' remains in its open position.

[0043] Finally, [Fig. 4] represents the fourth and final step of the sequence, in which the valve head 8 of the valve 7 of the first male fitting 1 is in its open position. The coupling device is then in its fluid passage position.

[0044] In a particularly advantageous way - as shown in [Fig.4] - the coupling device arrives in its clear position as soon as the coupling end 4 of the longitudinal body 2 of the first fitting 1 comes into contact with the bottom 19' of the housing recess of the coupling end 4' of the female fitting 1'.

[0045] The coupling device of the invention thus makes it possible to perform a coupling sequence between two fittings respectively male 1 and female 1' by minimizing, or even eliminating, leaks of cryogenic liquid at the level of said fittings 1, 1' and by minimizing the risk of overpressure between the two fittings male 1 and female 1'.

Claims

1. Demands Fluid line coupling device comprising a first fitting (1) forming a male part and a second cooperating fitting (1') forming a female part, the first fitting forming the male part (1) comprising: - a longitudinal body (2) which extends along a main axis (XX') from a junction end to a conduit (3) to a coupling end (4) to the second cooperating fitting (1') of the coupling device, which coupling end (4) has a fluid passage orifice (5) in fluidic communication with a flow channel (6) formed in the longitudinal body (2) and which extends from the coupling end (4) to the junction end (3), - a valve (7) disposed in the flow channel (6) of the longitudinal body (2), the main axis of which extends along the main axis (XX') of the longitudinal body (2) of the first fitting (1), and which comprises a valve head (8) located at the passage orifice (5) of the coupling end (4) of the longitudinal body (2) and movable longitudinally in the flow channel (6) between a clear position in which the passage orifice (5) is open and a closed, watertight position in which the passage orifice (5) is sealed by a watertight contact between the valve head (8) and a valve head seat (10) provided in the longitudinal body (2) and in the internal extension of the passage orifice (5), a free sealing end (11) of the valve (7) extending into the passage orifice (5) and projecting from the coupling end (4),which valve (7) further comprises first means (9) for returning the valve head (8) to its closed, sealed position, the second fitting (1') forming a female part comprising: - a longitudinal body (2') extending from a junction end (3') to a second conduit (3') and then to a coupling end (4') which surrounds the end of coupling (4) of the first fitting (1), which coupling end (4') has a fluid passage orifice (5') in fluidic communication with a flow channel (6') formed in the longitudinal body (2') and which extends from the coupling end (4') to the junction end (3'), - a valve (7') disposed in the flow channel (6') of the longitudinal body (2') and comprising a valve head (8') located at the passage orifice (5') of the coupling end (4') of the longitudinal body (2'), and which is movable longitudinally in the flow channel (6') from a clear position in which the passage orifice (5') is open, to a sealed position in which the passage orifice (5') is closed by a sealed contact between the valve head (8') and a valve head seat (10') provided in the longitudinal body (2') and in the extension of the passage orifice (5'), which valve (7') further comprises second means for returning the valve head (8') to its closed sealed position, the coupling device being actuable between a closed position in which the valve heads (8, 8') of the valves (7, 7') of the first and second fittings (1, 1') are in their sealed position and their free closing ends (11, 11') are touching, and a fluid passage position from the first male fitting (1) to the second female fitting (1') in which the first return means (9) of the valve head (8) of the valve (7) of the first male fitting (1) exert a force on the free end (11') of the valve (7') of the female fitting (1') and hold the valve head (8') of said valve (7') of the second female fitting (1') in its open position,and the second return means (9') of the valve head (8') of the valve (7') of the second female fitting (1') exert a force on the free end (11) of the valve (7) of the first male fitting (1) and maintain the valve head (8) of said valve (7) of the first male fitting (1) in its disengaged position, characterized in that the valve head (8) of the valve (7) of the first male fitting (1) is movable from its sealing position towards its clear position against the first return means (9) when the forces exerted on the free end (11) of said valve (7) is greater than a first release force FDM dependent on the first return means (9), in that the valve head (8') of the valve (7') of the second female fitting (1') is movable from its sealed position towards its clear position against the second return means (9') when the forces exerted on the free end (11') of said valve (7') are greater than a second release force Fdf dependent on the second return means (9'), in that the first release force FDM of the displacement of the valve head (8) of the valve (7) of the first male fitting (1) is greater than the second release force Fdf of the displacement of the valve head (8') of the valve (7') of the second female fitting (F),and in that the force exerted by the second actuation means (9') on the valve head (8) of the valve (7) of the first male fitting (1) is greater than the first triggering force FDM when the coupling device is in its fluid passage position, so that the valve head (8') of the valve (7') of the second female fitting (F) moves towards its clear position before the valve head (8) of the valve (7) of the first male fitting (1) when the coupling device moves from its closed position to its fluid passage position from the first male fitting (1) to the second female fitting (F).

2. Coupling device according to the preceding claim, characterized in that the coupling ends (4, 4') of the longitudinal bodies (2, 2') of the first and second fittings (1, F) are in contact support when the coupling device is in its fluid passage position from the first male fitting (1) to the second female fitting (F).

3. Coupling device according to claim 1 or 2, characterized in that the first return means (9) are formed of a first spring having the first release force FDM and a stiffness kM, and in that the second return means (9') are formed of a second spring having the second release force Fdf and a stiffness kF.

4. Coupling device according to the preceding claim, characterized in that the stiffness constant kM of the first spring (9) is expressed according to the formula [Math 1]: » » 10) kpF(F2-FDP) with F2 the force exerted against the two valve heads (8, 8') of the valves (7, 7') of the male (1) and female (1') fittings when the coupling device is in its fluid passage position, and b the distance between the coupling ends (4, 4') of the longitudinal bodies (2, 2') of the first and second fittings (1, 1') when the coupling device is in its closing position.

5. A method for coupling a coupling device according to any one of the preceding claims, characterized in that it comprises the following successive steps: - With the coupling device in its closed position and the valve heads (8, 8') of the valves (7, 7') of the first male fitting (1) and the second female fitting (1') in their closed, sealed position, a progressively bringing the two male and female fittings (1, 1') together is applied; - Progressive movement of the valve head (8') of the valve (7') of the second female fitting (1') towards its clear position as soon as the approach force exerted on the end (11') of said valve (7') of the second female fitting (1') exceeds the value of the second triggering force Fdf, the valve head (8) of the valve (7) of the first male fitting (1) remaining in its closed position of watertight grip; - Progressive movement of the valve head (8) of the valve (7) of the first male fitting (1) towards its clear position as soon as the approach force exerted on the end (11) of said valve (7) of the first male fitting (1) exceeds the first FDM triggering force, the valve head (8') of the valve (7') of the second female fitting (1') being in its clear position; - Arrival of the valve head (8) of the valve (7) of the first male fitting (1) in its clear position and of the coupling device in its fluid passage position.

6. 15 Method according to the preceding claim, characterized in that the coupling device arrives in its clear position as soon as the coupling ends (4, 4') of the longitudinal bodies (2, 2') of the first and second fittings (1, 1') come into contact support.

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