WO2006043883A1

WO2006043883A1 - Coupling device for transferring a fluid

Info

Publication number: WO2006043883A1
Application number: PCT/SE2005/001552
Authority: WO
Inventors: Henrik Ingvarsson
Original assignee: Nhi Consulting Ab
Priority date: 2004-10-22
Filing date: 2005-10-19
Publication date: 2006-04-27
Also published as: SE0402581L; SE0402581D0

Abstract

Coupling device intended for transferring a flow of a substance, which device comprises a first coupling element (1 ) and a second (21 ) coupling element. The first coupling element (1 ) comprises a fluid channel and a first sealing element (9) displaceable from a sealing position under the effect of spring force, and also a rigid first displacing element (8). The second coupling element (21 ) comprises a fluid channel and a second sealing element displaceable from a sealing position under the effect of spring force and also a rigid second displacing element. Said sealing elements on each coupling element are arranged to sealingly close the inlet (outlet) of the fluid channel when the two coupling elements are separated. The first displacing element (8) is arranged to displace the second sealing element out of the sealing position when the said coupling elements (1 and 21) are coupled together and the second displacing element is arranged to displace the first sealing element (9) on the first coupling element (1 ) out of the sealing position when the said coupling occurs. The two coupling elements have smooth coupling surfaces, which after coupling together of the coupling elements are separated from the flow through the fluid channels.

Description

COUPLING DEVICE FOR TRANSFERRING A FLUID

TECHNICAL FIELD

The present invention concerns a coupling device intended for transferring a fluid in gas or liquid form or in the form of an aerosol, which device comprises a first coupling element and a second coupling element releasably connectable with the first coupling element, that the first coupling element comprises a fluid channel and a first sealing element displaceable from a sealing position under the effect of spring force in a direction opposite to the coupling direction and also a rigid first displacing element, that the second coupling element comprises a fluid channel and a second sealing element displaceable from a sealing position under the effect of spring force in a direction opposite to the coupling direction and also a rigid second displacing element, that said sealing elements on each coupling element are arranged to, in said sealing position, sealingly close the inlet (outlet) of the fluid channel when the two coupling elements are separated, that the first displacing element is arranged to displace the second sealing element out of the sealing position when the said coupling elements are coupled and that the second displacing element is arranged to displace the first sealing element on the first coupling element out of the sealing position when the said coupling of the two coupling elements occurs.

BACKGROUND

Coupling devices of the type mentioned above that are used for, for example, medical purposes such as transferring blood or medicines from a container to a patient, must fulfil very high standards with regard to safety. It is of course important that blood or medicine that is to be supplied to a patient is not contaminated when the fluid passes the coupling device. In addition, it is important that air from the environment cannot penetrate via the coupling device when it is disconnected or connected. In many situations it is important to avoid spillage from the coupling device when it is to be disconnected after use. Employees would otherwise risk exposure to infectious substances or dangerous medicines.

The coupling device in accordance with the invention is intended for transfer of liquids, gases and aerosols. As well as in medical situations, there is a need for safe couplings in the chemical and biological industries for transfer of dangerous substances in gas or liquid form or in the form of aerosols. The coupling device in accordance with the present invention is also intended for such purposes.

A great number of coupling devices of the type mentioned in the introduction are previously known but these do not function satisfactorily in ail respects with regard to safety.

US 6 168 137 describes a one-way coupling with a rigid first displacing element in the form of a tube with a closed free tube end and a peripheral hole arranged near said tube end. The fluid channel of the coupling extends through the hole and the tube. This one-way coupling also includes a sealing sleeve fitted on the tube, which sleeve in its sealing position is arranged to seal the hole and which is displaceable from its sealing position under the effect of spring force. This one-way valve is arranged to cooperate with an injection device for transferring a fluid from the device via the one-way coupling to a catheter or a container. A considerable disadvantage with the one-way coupling in accordance with the above-mentioned patent is that it has outer parts that are in contact with the environment before connection of the injection device and which the fluid in the fluid channel passes after connection. A similar coupling with the same disadvantages is described in US 5 776 113.

A coupling device of the type in the introduction is described in US 5 738 144. This device comprises a first coupling element, which has parts that are in contact with the environment before the two coupling elements are coupled together and that the fluid passes in the fluid channel after the coupling. During use of this coupling device there is a risk that said outer parts are contaminated and that the supplied medium can be contaminated. Furthermore, leakage from said outer parts occurs when the two coupling elements are separated. A further disadvantage with the construction in accordance with US 5 738 144 is that air is pressed into the fluid channel when the two coupling elements are coupled together.

A coupling device of the type mentioned in the introduction is known from EP 0 080 379 B1. This coupling device has the disadvantage that one of the coupling elements, when it is coupled together with the other, has a quantity of enclosed air, which can be contaminated and which, when the coupling takes place, is pressed in past a sealing element in the said coupling element and into the fluid channel.

A coupling device of the type mentioned in the introduction is also known from EP 0 087 901 A2. When the two coupling elements are joined together, the coupling device according to this publication has a space included in the through fluid channel, between the two coupling elements. The supply of fluid to this space continues until the sealing element seals, which does not occur until the coupling elements are completely separated. Fluid in this space must go somewhere, which leads to leakage when the two coupling elements are separated. The problem increases when there is internal overpressure in the system.

A purpose of the present invention is to design a coupling device in which no external surfaces, i.e. surfaces which are exposed to contamination from the environment when the coupling parts are separated, can be reached by the flow through the fluid channels.

A further purpose is to ensure that there are no air pockets between the two coupling elements when they are coupled together, which air pockets can lead to contaminated air being pressed into the fluid channel. A further purpose is to obtain a coupling device with which spillage into the environment is eliminated.

DESCRIPTION OF THE INVENTION

The above-mentioned purpose is achieved according to the invention in a coupling device of the type mentioned in the introduction in that the first displacing element is constituted by a tube with a closed tube end, that at least one radial hole is arranged near said tube end, that the fluid channel of the first coupling element extends through the hole and said tube, that the first sealing element is constituted by a sleeve displaceably fitted on the tube, which sleeve is arranged, in said sealing position, to sealingly close the hole, that the free end of the sleeve is arranged, in a fixed sealing position, to coincide with the end of the tube and to form together with it a smooth continuous first coupling surface, that the first sealing element is arranged to be brought by said spring force to the fixed sealing position and in this position to sealingly surround the first displacing element from said tube end and in over the entire hole, that the sealing element is arranged to form a gas- and liquid-impermeable seal around the tube, that the second displacing element is constituted by a sleeve-formed end part of a valve housing, that the second sealing element is constituted by a valve body fitted in said valve housing, that this valve body is arranged to be brought by means of said spring force to a fixed sealing position, that the valve body has a cylindrical end part with a free end, that this end part is arranged to seal a cylindrical hole in the sleeve-formed end part of the valve housing, that the valve body from said cylindrical end part in a direction away from the free end of the valve body becomes a sealing part that is enlarged in relation to the end part, which sealing part is arranged to cooperate with a valve seat, adapted to this sealing part, in the valve housing, which valve seat is arranged immediately adjacent to said cylindrical hole in the sleeve-formed end part, that the enlarged part of the valve body is arranged to radially lie sealingly against the inner wall of the valve housing in order to prevent the flow of liquid and gas between the envelope surface of the valve body and the inner wall of the valve housing, that said inner wall of the valve housing is arranged to guide the axial movement of the valve body, that the free end of the sleeve-formed end part of the valve housing is arranged to coincide, in its sealing position, with the free end of the cylindrical end part of the valve body and together with this to form a plane continuous second coupling surface, that said first and second coupling surfaces are plane or curved with the same curve radius, that, when the coupling surfaces are curved, one of the coupling surfaces is convex and the other is concave, whereby when the two coupling elements are coupled together a completely smooth first coupling surface formed by the first displacing element and the first sealing element is brought against a similarly completely smooth second coupling surface formed by the second displacing element and the second sealing element, that during connection of the two coupling elements the first and second sealing elements are arranged to cooperate with the first and second displacing elements in said coupling surfaces in order to prevent gas or liquid from penetrating in between the first and second coupling surfaces, that the sleeve-formed end part of the valve housing, which part serves as the second displacing element, is arranged to temporarily close the hole near said tube end during coupling together and disconnection of the two coupling elements and is arranged to form a seal around the tube after passing the hole, that the free end of the valve body has a size and shape that correspond to the size and shape of said closed tube end on the first displacing element, whereby outer coupling surfaces that are possibly contaminated from the environment are separated from the flow through the fluid channels through the first and second coupling elements when these have been coupled together, are being coupled together and are being separated.

The coupling surfaces of the first sealing element and the second displacing element which are on the exterior when the coupling elements are separated will thus be encapsulated in the coupling device and the seal around the tube formed by the sleeve-formed end part of the valve housing prevents the flow through the flow channel from reaching the above-mentioned coupling surfaces. As the remaining parts of the first and second coupling surfaces are mutually covered, all of the outer surfaces on both coupling elements are always separated from the flow through the coupling device. Thus, any contaminated outer surfaces cannot come into contact with the fluid.

As the said first and second coupling surfaces are completely smooth when coupling together of the two coupling elements is initiated, no pockets of air can occur between the coupling elements when these are coupled together.

Furthermore, it is easy to clean/disinfect the coupling surfaces, which are completely smooth before coupling.

Spillage from the coupling device during separation of the coupling elements has been eliminated by the temporary sealing of the hole by means of the sleeve-formed end part of the valve housing in combination with the fact that the cylindrical end part of the valve body seals the cylindrical hole in the sleeve-formed part of the valve housing before the enlarged part of the valve body seals against the valve seat.

According to one embodiment, the coupling device in accordance with the invention is further characterised in that, when the two coupling elements are coupled together, the cylindrical end part of the valve body is arranged to be pushed in its entirety into the remainder of the valve body before the enlarged sealing part is brought to leave its sealing position against the valve seat.

Further embodiments of the invention can be seen in the patent claims below.

DESCRIPTION OF THE FIGURES

The invention will be described below in greater detail with reference to embodiments shown in the attached drawings. In which Fig. 1 shows a longitudinal section through a first coupling element forming part of the coupling device in accordance with the invention in a free position,

Fig. 2 shows a longitudinal section through a second coupling element forming part of the coupling device in accordance with the invention in a free position,

Fig. 3 shows the coupling elements according to Figs. 1 and 2 in a position immediately before coupling,

Fig. 4 shows the coupling device in accordance with Fig. 3 with the coupling elements coupled together,

Fig. 5 shows a modified embodiment of the coupling device in accordance with the invention in a position immediately before coupling

Fig 5a shows a valve body forming part of the coupling device in accordance with Fig. 5,

Fig. 6 shows the coupling device in accordance with Fig. 5 with the coupling elements coupled together,

Fig. 6a shows the valve body in accordance with Fig. 5 in the position it assumes when the coupling elements are coupled together,

Fig. 7 shows a valve body which has been modified in relation to the embodiment according to Fig. 5a, in a sealing position,

Fig. 8 shows the valve body in accordance with Fig. 7 in a compressed state.

DESCRIPTION OF THE EMBODIMENTS

Fig.1 shows a first coupling element 1 in a free position. The coupling element has an essentially cylinder-shaped coupling member 2, which is rigidly connected to a connection means 3. This is arranged as an inlet or outlet for liquid or gas that is to be transported through the coupling device. In the shown embodiment, the connection means is formed for connection of a tube or the like. The connection means has a through channel which is in direct communication with the interior of a tube 4, which, as can be seen from Fig.1, is rigidly connected to the cylinder-shaped coupling member 2 and is coaxial with it. The tube 4 has a plane closed tube end 5 and a radial, cylindrical through hole 6 near the plane end of the tube and being in direct communication with the interior of the tube. The tube 4 with its plane end is also intended to serve as a first displacing element 8 comprised in the coupling device, the function of which is described in more detail below. The first coupling element comprises a first sealing element 9 in the form of a sleeve which is displaceably fitted on the tube 4. In Fig. 1 , this sealing element is shown in its sealing position, in which the sleeve is arranged to sealingly close the hole 6. The sleeve is spring-loaded by the spring 10 and is pushed by it into a fixed sealing position, in which an enlarged part 11 of the sleeve lies against a stop lug 12 on the coupling member 2. The sealing element 9 is arranged to form a gas- and liquid-impermeable seal around the tube 4. The first sealing element 9 is formed so that the end surface 5' on the first displacing element 8 and the end surface 9' on the first sealing element 9 lie in a plane and form a completely smooth first coupling surface 13 when the sealing element is in its sealing position and the fluid channel through the tube 4 and the hole 6 is closed. In the embodiment shown in Fig.1, the free end of the cylinder-shaped coupling member 2 is in line with said first coupling surface. This is not essential to the function of the coupling device, the device being able to be formed with said free end located either inside or outside of said first coupling surface when the first sealing element is in a free position, i.e. with the first sealing element in its fixed sealing position.

Fig.2 shows a second coupling element 21 comprised in the coupling device, in a free position, in which the fluid channel through this coupling element is closed. The coupling element 21 has a sleeve-formed part 22, which is intended to serve as a coupling member for connection to the coupling member 2 on the first coupling element. The sleeve-formed part 22 is rigidly connected to a valve housing 23, which has a sleeve-formed end part 24, which is arranged to serve as a second displacing element comprised in the coupling device, the function of which is described in greater detail below. A valve body 25 is fitted inside the valve housing 21. This valve body has a cylindrical end part 26 with a plane free end 26'. The cylindrical end part 26 is arranged to seal a cylindrical hole in the sleeve-formed end part 24 of the valve housing. In a direction away from the free end of the valve body, the end part of the valve body becomes an enlarged sealing part 27, which is arranged to cooperate with a valve seat 28 in the valve housing. As is evident from the drawing, this is arranged immediately adjacent to said cylindrical hole. The second coupling element has a spring 29, which is arranged to push the valve body towards a fixed sealing position, in which said enlarged sealing part 27 lies against the valve seat 28. The free end 24' of the sleeve- formed end part 24 is plane. The second coupling element is formed in such a way that the free plane end 26' of the valve body is in line with the plane free end 24' of the sleeve-formed end part 24, whereby the second displacing element in the form of the sleeve-formed end part 24 of the valve housing and the second sealing element in the form of the sleeve-formed end part of the valve body form a completely smooth second coupling surface, which is denoted 30 in the drawing. The free end of the sleeve-formed part 22, which serves as a second coupling member, extends in an axial direction outside said second coupling surface 30. This sleeve-formed part thus protects this coupling surface from outside influences. The second coupling element comprises a flow channel in the form of a tube-like part 31 , which is formed in one piece with the valve housing in the shown embodiment. This tube-like part has an opening 32 towards the interior of the valve housing, which opening is closed off by the valve body when it is in its sealing position. The enlarged part of the valve body lies sealingly against the inner walls of the valve housing in order to prevent a flow of gas and liquid between the envelope surface of the valve body and the inner wall of the valve housing. The tube-like part 31 has a connection means 33, which serves as an inlet or outlet for the liquid or gas that is to be transported through the coupling device. In the shown embodiment this coupling means is formed for coupling to a tube or the like.

Fig. 3 shows the two coupling elements comprised in the coupling device immediately before they are coupled together. The outer periphery of the coupling member 2 fits into the sleeve-formed part 22, which forms a coupling member in the second coupling element, whereby the two coupling elements are guided into the correct position during coupling. During coupling, said plane and smooth first coupling surface on the first coupling element is brought into contact with a similarly plane and smooth second coupling surface 30 on the second coupling element, thus preventing air pockets from arising between the coupling elements and the risk of contaminated air coming into the fluid channel of the coupling device. The free end of the valve body has a size and shape which corresponds to the size and shape of the said plane and closed tube end on the first displacing element 8.

When the two coupling elements are coupled together, the second sealing element, the valve body 25, is displaced under the force of the spring 29 by the first displacing element 8 out of its fixed sealing position. At the same time, the first sealing element 9 is displaced by the second sealing element, the sleeve-formed end part 24, out of its fixed sealing position under the force of the spring 10. The sleeve-formed end part 24 is arranged, during displacement of the first sealing element, to temporarily close the hole 6 near said tube end and is arranged, after the passage of the hole 6, to form a seal around the tube. In this way, the outer free end surfaces on the second displacing element and on the first sealing element, which may have been contaminated before coupling together, are encapsulated at a distance from the hole 6 and are prevented from coming into contact with the flow through the fluid channel. Furthermore, since the plane end surface of the first displacing element 8 has a size and shape which wholly correspond to the size and shape of the free end of the valve body, the fluid which passes through the fluid channel in the second coupling element will not come into contact with any free surfaces which may possibly be contaminated by the environment.

As the coupling surfaces 13 and 30 of the two coupling elements 1 and 21 are completely smooth, they are easy to disinfect or clean in any other way.

Fig. 4 shows the two coupling elements 1 and 21 in coupled position. The two coupling elements are locked in this position due to cooperation between locking members on the two coupling members 2 and 22. These locking members (not shown) can be constituted by a screw joint, a bayonet connection or another suitable locking device. In this coupled position, a flow of gas, liquid or aerosol can pass through the inlet (outlet) 3 of the coupling device via the tube 4 and its hole 6, via the inner space 34 of the valve housing around the cylindrical end part 26 of the valve body, which has been displaced out of its sealing position, via the opening 32 to the fluid channel in the tube-like part 31 and finally via the connection means 33, which constitutes an inlet (outlet) to the coupling member.

It has been described above how the two coupling elements, which are closed when in the free position, can be safely coupled together without risk of contaminating the flow through the fluid channel. During use of the coupling device for transport of a fluid which should not come into contact with the environment, it is also important that the coupling element can be disconnected without risk of spillage of the flow of liquid or gas into the environment. This is achieved by the second displacing element temporarily sealing the hole 6 to the fluid channel through the tube 4 during disconnection. This occurs before the opening 32 to the fluid channel through the tube-like part 31 is closed by the valve body. This, and the opening 32 are dimensioned so that gas or liquid in the space 34 are forced out through the opening 32 when the hole 6 is closed and the valve body moves towards its fixed sealing position. In the shown example a groove 32', which extends between the opening 32 and the valve seat 28, is arranged for this purpose. Fig. 5 shows an embodiment of the coupling device, which has been somewhat modified in relation to the embodiment in Figs 1-4, in a position corresponding to that shown in Fig. 3, i.e. immediately before coupling together with mutual displacements of the sealing elements has begun. The parts in the embodiment according to Fig. 5 that correspond to the same details in the embodiment according to Fig. 3 have been given the same reference numerals and are not described in any more detail here. One difference is the design of the valve body. Its outer form corresponds in the shown embodiment with the outer form of the valve body according to Fig. 3. The valve body 25, as can be seen in Figs 5 and 5a, consists of two mutually displaceable components 251 and 252. The cylindrical end part constitutes a part 253 of a first component 251. This first component is formed in one piece and has a second part 254, which, when the valve body is in its fixed sealing position, extends into a cavity 255 in the second 252 of the said components, which is constituted by the remainder of the valve body, i.e. the enlarged part of the valve body. The first component is arranged displaceably in said cavity 255 against the force of a spring 256 located in the cavity. As in the embodiment according to Fig. 3, the valve body in its entirety is displaceably brought from its fixed sealing position under the force of the spring 29. The spring force in the spring 256 is made so much lower than the spring force in the spring 29 that the cylinder-formed end part of the valve body, i.e. part 253, is displaced in its entirety a distance into the cavity 255 of the first displacing element before the valve body in its entirety is displaced under the force of the spring 29. This is illustrated in Fig. 6, which shows the coupling device according to Fig. 5 in a completely coupled together position. The purpose of the construction according to Figs. 5 and 6 is that, in the coupled position of the coupling device, an end part of the first displacing element has penetrated into the cavity 255, so that the free plane end surface of the first displacing element is encapsulated in the cavity and cannot be reached by the flow through the fluid channel. In this embodiment, the cavity, the first displaceable component and the tube are formed in such a way that the second component 252 forms a seal around the first component and also round the first displacing element in the cavity. This is most clearly revealed in Fig. 6a. In the embodiment shown here, a groove 257 is arranged in the valve housing, which groove is in line with the groove 32' but is deeper and forms part of the fluid channel through the coupling device in this embodiment.

Figs. 7 and 8 show a modified embodiment of a valve body with the same function as has been described in connection with Figs. 5 and 6. As can be seen from Fig. 8, the cylinder-shaped end part 251 is intended to be pushed into the remainder of the valve body, i.e. the enlarged part 252. This is made of an elastic resilient material, which regains its shape when the two coupling devices are disconnected from one another. The two components 251 and 252 can be composed of different material. The first component 251 can be rigid while the second component is elastically resilient. Both components can also be composed of resilient elastic material. What is essential is that the cylindrical end part of the valve body is displaced in its entirety into the remainder of the valve body before the fluid is permitted to pass through the coupling device.

The invention is not limited to the embodiments described above, one or several modifications being possible within the framework of the following claims. For example, the springs 10 and/or 29 can be eliminated and replaced by the valve body and /or the first sealing element if these parts are formed of elastic, compressible and resilient material and also if these parts are arranged pretensioned when each of the coupling elements is in free position, i.e. not mutually coupled. The two coupling surfaces 13 and 30 have been described above as completely plane. However, they can also be constituted by curved surfaces of which one is convex and the other is concave. The coupling surfaces can, for example, be partly spherical. What is essential is that the surfaces fit together so that no air pockets can form between the coupling elements when they are coupled together.

Claims

1. Coupling device intended for transferring a fluid in gas or liquid form or in the form of an aerosol, which device comprises a first coupling element (1 ) and a second coupling element (21 ) releasably connectable with the first coupling element, that the first coupling element (1 ) comprises a fluid channel and a first sealing element (9) displaceable from a sealing position under the effect of spring force in a direction opposite to the coupling direction and also a rigid first displacing element (8), that the second coupling element (21) comprises a fluid channel and a second sealing element displaceable from a sealing position under the effect of spring force in a direction opposite to the coupling direction and also a rigid second displacing element, that said sealing elements on each coupling element are arranged to, in said sealing position, sealingly close the inlet (outlet) of the fluid channel when the two coupling elements are separated, that the first displacing element (8) is arranged to displace the second sealing element out of the sealing position when the said coupling elements (1 and 21) are coupled and that the second displacing element is arranged to displace the first sealing element (9) on the first coupling element (1 ) out of the sealing position when the said coupling of the two coupling elements occurs, c h a r a c t e r i z e d i n that the first displacing element (8) is constituted by a tube (4) with a closed tube end (5), that at least one radial hole (6) is arranged near said tube end (5), that the fluid channel of the first coupling element (1) extends through the hole (6) and said tube (4), that the first sealing element (9) is constituted by a sleeve displaceably fitted on the tube, which sleeve is arranged, in said sealing position, to sealingly close the hole (6), that the free end (9') of the sleeve is arranged, in a fixed sealing position, to coincide with the end of the tube and to form together with it a smooth continuous first coupling surface (13), that the first sealing element (9) is arranged to be brought by said spring force to the first sealing position and in this position to sealingly surround the first displacing element (8) from said tube end (5') and in over the entire hole (6), that the sealing element (9) is arranged to form a gas- and liquid-impermeable seal around the tube (4), that the second displacing element is constituted by a sleeve-formed end part (24) of a valve housing (23), that the second sealing element is constituted by a valve body (25) fitted in said valve housing, that this valve body is arranged to be brought by means of said spring force to a fixed sealing position, that the valve body has a cylindrical end part (26) with a free end (26'), that this end part is arranged to seal a cylindrical hole in the sleeve- formed end part (24) of the valve housing, that the valve body (25) from said cylindrical end part (26) in a direction away from the free end of the valve body becomes a sealing part (27) that is enlarged in relation to the end part, which sealing part is arranged to cooperate with a valve seat (28), adapted to this sealing part, in the valve housing, which valve seat is arranged immediately adjacent to said cylindrical hole in the sleeve-formed end part (24), that the enlarged part (27) of the valve body (9) is arranged to radially lie sealingly against the inner wall of the valve housing in order to prevent the flow of liquid and gas between the envelope surface of the valve body and the inner wall of the valve housing, that said inner wall of the valve housing is arranged to guide the axial movement of the valve body, that the free end (24') of the sleeve-formed end part of the valve housing is arranged to coincide, in its sealing position, with the free end (26') of the cylindrical end part of the valve body and together with this to form a plane continuous second coupling surface (30), that said first and second coupling surfaces are plane or curved with the same curve radius, that, when the coupling surfaces are curved, one of the coupling surfaces is convex and the other is concave, whereby when the two coupling elements are coupled together a completely smooth first coupling surface (13) formed by the first displacing element and the first sealing element is brought against a similarly completely smooth second coupling surface (30) formed by the second displacing element and the second sealing element, that during connection of the two coupling elements the first and second sealing elements are arranged to cooperate with the first and second displacing elements in said coupling surfaces in order to prevent gas or liquid from penetrating in between the first and second coupling surfaces, that the sleeve-formed end part (24) of the valve housing, which part serves as the second displacing element, is arranged to temporarily close the hole (6)near said tube end during coupling together and disconnection of the two coupling elements and is arranged to form a seal around the tube (4) after passing the hole, that the free end (26') of the valve body has a size and shape that correspond to the size and shape of said closed tube end (5') on the first displacing element, whereby outer coupling surfaces that are possibly contaminated from the environment are separated from the flow through the fluid channels through the first and second coupling elements when these have been coupled together, are being coupled together and are being separated.

2. Coupling device in accordance with claim 1, characterized in that when the two coupling elements are coupled together, the cylindrical end part (26) of the valve body (25) is arranged to be pushed in its entirety into the remainder of the valve body before the enlarged sealing part (27) is brought to leave its sealing position against the valve seat (28).

3. Coupling device in accordance with claim 2, characterized in that the cylindrical end part (26) of the valve body is rigid and that the remainder of the valve body is constituted by resilient compressible material.

4. Coupling device in accordance with claim 2, characterized in that the cylindrical end part (251 ) of the valve body is comprised of a first compressible material and that the remainder of the valve body (252) is comprised of an second compressible material.

5. Coupling device in accordance with claim 2, characterized in that the valve body consists of two mutually displaceable components (251 , 252), that the cylindrical end part constitutes a part (253) of a first of said components, that this first component (251) is formed in one piece and has a second part (254), and is arranged displaceably against the force of a spring (256) inside a cylindrical cavity (255) in a second (252) of said components, which second component is constituted by the remainder of the valve body and which in turn is displaceable against the first-mentioned spring force, and that the spring force for said spring inside the cylindrical cavity is so much lower than the first-mentioned spring force that said cylindrical end part (253) is pushed in its entirety into the cavity and that the end part (5) of the first displacing element (8), the tube (4), in front of the hole (6) in the tube penetrates into the cavity, and that the latter end part and the cavity are formed so that the end part (5) is brought into a sealing engagement with the cavity.

6. Coupling device in accordance with any one of the previous claims, c h a r a c t e r i z e d i n that the first coupling element (1) has a first coupling member (2) intended for coupling with the second coupling element (21) via a second coupling member comprised in the second coupling element and cooperating with the first coupling member, that at least one of said first and second coupling members is constituted by a sleeve-formed part (22) with a greater diameter than the extension in the same direction of said first and second coupling surfaces (13, 30), and that said sleeve-formed part (22) on at least one of the coupling elements is arranged, when the coupling elements (1, 21) are separated, to extend in the coupling direction with its free end a distance outside the coupling surface (30) on the coupling element in question, whereby this coupling surface is protected from undesired contact when the coupling elements are separated.

7. Coupling device in accordance with any one of the previous claims, c h a r a c t e r i z e d i n that a channel part located radially outside the valve body and extending in the coupling direction is comprised in the fluid channel through the second coupling element (21 ).