Field of the invention.

The invention relates to a tube coupling, comprising a coupling housing having a recess therethrough, a clamping ring arranged such that the tube, during connection, can be inserted into the recess and, upon insertion, be retained in the recess, said clamping ring being situated in the recess, and at least one annular gasket, for instance an 0-ring, for sealing between the recess and the connected tube.

Prior art.

A tube coupling of the above kind is known from NO Patent No. 149598. The housing of the coupling consists of two parts, whereby the clamping ring and the adjacent gasket kan be placed between the parts of the housing prior to connecting them by means of a threaded connection. Oppositely of the clamping ring, seen relatively to the direction of inserting the tube, the gasket engages an end surface on one of the housing parts. In order to ensure that the clamping ring, upon connection, is able to clamp the tube in the housing of the coupling, the recess in the second housing part has a tapering or conical portion, against which the clamping ring is lying. The clamping ring is configured with a suitable cross sectional shape which, in cooperation with said tapering portion, causes that the tube is clamped if an attempt is made to pull the tube out of the housing of the coupling, upon connection. In order to avoid that i. a. increase of temperature will cause reduced clamping action between the tube and the clamping ring (due to softening of the tube), one of the housing parts can be configured with an inner support sleeve which lies supporting inside the connected tube, at least in a portion surrounded by the clamping ring.

During use the known tube coupling functions very well. However, that the housing of the coupling consists of two housing parts, for placement of the clamping ring and the adjacent gasket in the recess, makes the manufacture and connection of the tube coupling more expensive. Moreover, there will be more possible leakage paths for fluid flowing through the tube coupling, and an increased amount of material will be needed in the blanks for the housing of the coupling.

NO Patent Application 1999 1487 describes a coupling having a housing which contains a clamping ring, a support sleeve integral with a disc and a sealing ring. These elements are not locked in the housing of the coupling, but may be moved out of the housing of

the coupling by passing a threaded portion inside the housing of the coupling. The threaded portion is adapted for screwing the housing of the coupling onto an end of a tube. Not until such screwing on, the inner parts in the housing of the coupling are locked against being moved out of the housing, in that the sealing ring, being the axially outermost of the elements, is pressed against the end surface of the tube end.

EP Patent Application 0811801 shows a similar principle, except that a second sealing ring inside the housing of the coupling engages the clamping ring and that a third sealing ring is inserted in an annular groove in the support sleeve.

GB Patent 2226861 shows a coupling housing having an inner channel with a stepwisely increasing diameter towards the end from which a tube is to be inserted. Internal elements in the housing of the coupling are inserted from this end. A sleeve containing a clamping ring is pressed into the portion of the channel having the largest diameter, and the sleeve has a conical inner surface, against which the clamping ring is compressed.

The sleeve acts as an internal liner. The coupling does not permit the use of a support sleeve inside the tube.

DE Patent Application 4005826 shows a coupling composed of two housing parts being screwed together. A disc having a support sleeve is held by one of the housing parts, and a clamping ring in the other housing part engages a conical surface in the other housing part and in the disc, whereby the clamping ring is pressed against the tube in two areas. The disc and the support sleeve will not be kept in place unless the housing parts are screwed together.

Summary of the invention.

With the invention a tube coupling has been provided which permits locking of the sleeve. Thereby, the sleeve prevents that other elements inside the housing of the coupling can fall out prior to mounting of the housing of the coupling.

The tube coupling according to the invention comprises a housing formed by a single part, and one end portion of the recess has a larger diameter than the opposite end portion of the recess. The clamping ring, and a possible annular gasket, can be held in the recess even when the coupling is not connected to another element. A disc having an axial aperture for flow-through is locked against axial movement in or near the end portion having the largest diameter, due to the fact that the disc comprises a set of

outer, axially extending snap arms, each configured with an outwardly extending portion that can be retained in an annular groove formed in the end portion having the largest diameter. Thereby, the clamping ring and a possible annular gasket inserted in the coupling housing are locked against falling out of the coupling housing.

In the following part of the description a preferred embodiment of the invention will be explained more detailed, with reference to the accompanying drawing.

Brief explanation of the drawing.

Fig. 1 shows a longitudinal section through a tube coupling according to the invention, which comprises a coupling housing having a recess therethrough, a clamping ring inserted in the recess for retaining of a tube inserted in the recess, and two gaskets for sealing between the connected tube and the recess.

Fig. 2 shows in perspective means adapted for retaining the clamping ring and the adjacent gasket inside the recess, and the clamping ring, the gasket and the retaining means are during assembly inserted into the housing through the end portion of the recess having the largest diameter.

Description of an embodiment The shown tube coupling comprises a coupling housing 1 having a recess 2 therethrough, a clamping ring 4 placed in the recess 2 and gaskets 5,14, for instance O- rings, for sealing between the recess 2 and a connected tube 3. The clamping ring 4 is in a known manner arranged such that the tube 3 during connection can be inserted into the recess 2 and upon connection is retained in the recess 2. The housing of the coupling is formed by a single part 1, and one end portion 7 of the recess 2 has larger diameter than the opposite end portion 8 of the recess 2. Between the end portions 7,8 of the recess is an intermediate, tapering portion 9. The tapering portion 9 may for instance be rectilinear between the end portions 7,8; i. e. that it is purely conical. The gaskets 5,14 are placed in annular grooves 13,6 formed in the recess 2. The annular groove 13 is situated adjacent the intermediate, tapering portion 9, and the annular groove 6 is situated adjacent the end portion 8 having the smallest diameter.

The clamping ring 4 is placed near the tapering portion 9 of the recess 2, adjacent the gasket 5. Moreover, the clamping ring 4 is configured with a suitable sectional shape which causes that the clamping ring 4, in cooperation with the tapering portion 9, retains the tube 3 if an attempt is made, upon connection, to pull the tube 3 out of the housing

of the coupling. This may be achieved in that one end portion of the clamping ring has a triangular shape, whereby the surface facing the tapering portion 9 is incline inwardly towards the tube 3, correspondingly as the tapering portion 9. The surface of the triangular portion facing the tube 3 may be correspondingly incline outwardly from the tube 3. Similarly, the portion of the surface of the clamping ring 4 facing the tube 3 extends mainly parallelly to the tube 3, and in the transition between the inwardly facing surfaces the clamping ring has an annular rib forming an edge for cutting into the wall of the tube. Thereby, the clamping ring 4 will, by an attempt to pull the tube 3 out of the housing 1 of the coupling, be moved up along the tapering portion 9 of the recess 2 and is compressed against the tube 3, whereby the rib will be forced further into the wall of the tube, and the parallel portion will clamp even more against the tube, as a safeguard against pulling out from the housing 1 of the coupling. In order to permit that the tube 3, during insertion into the housing 1 of the coupling, may pass the gasket 5 without any significant resistance, the clamping ring 4 can be formed with an incline surface which to a certain degree expands the gasket 5 when the clamping ring 4 is pushed inwardly of the coupling part during insertion of the tube 3.

The clamping ring 4 and the adjacent gasket 5 have been inserted into the recess 2 through the end portion 7 having the largest diameter, and are retained by means of the disc 12 having snap arms 10. The disc 12 has been inserted into the same end portion 7 after the clamping ring 4 and the gasket 5 are placed in the recess 2. The means for retaining the clamping ring 4 and the gasket 5, possibly also for internal support of the tube 3, comprises in the example shown a disc 12 equipped with a set of outer snap arms 10, arranged such that outwardly directed portions (hooks) 16 on the snap arms 10 may be retained in the annular groove 13 adjacent the tapering portion 9 of the recess 2, and simultaneously the snap arms 10 may form an abutment for the gasket 5. The outwardly directed portions or hooks 16 on the snap arms will during insertion into the housing 1 of the coupling be displaced by engaging the side wall of the recess 2, whereby the snap arms 10 are deflected elastically inwardly, until the annular groove 13 is reached, whereupon the snap arms 10 return due to resilience and the outwardly directed portions or hooks 16 come into locking cooperation with the annular groove 13.

The annular groove 13 may as shown have a smaller depth in an area near the snap arms 10 than at the gasket 5. For internal support of the tube 3 the disc 12 comprises an inner support sleeve 11 integral with the disc 12 and which may extend from the inner end of the tube 3 to at least the area near the clamping ring 4. The support sleeve 11 will be lying in close engagement with the inner wall of the connected tube 3. The

disc 12 will then constitute an end abutment for the tube during insertion into the housing 1 of the coupling. The disc 12 for retaining of the clamping ring 4 and the gasket 5, possibly also for support of the tube on the internal side, may for instance be formed of plastic material.

Thus, the tube coupling comprises a coupling housing 1 comprising only a single part, whereby manufacture and connection of two housing parts are eliminated. Locking of the clamping ring 4 and the gasket 5 in the housing of the coupling and keeping them in a correct position until the tube 3 is inserted are caused by the disc 12, which is mounted very simply by being pushed axially into the housing of the coupling by elastic flexing of the snap arms 10 and is locked by engagement of the hooks 16 in the annular groove 13. The snap arms 10 are prevented from flexing out of the annular groove upon insertion of the tube 3, in that the end of the tube 3 fills the space between the support sleeve 11 and the snap arms 10 when the support sleeve 11 is present, or in that the end of the tube 3 engages the snap arms 10 by its outer surface and prevents inward flexing of the snap arms 10 due to its stiffness.

The tube coupling according to the invention is particularly advantageous for connection of plastic tubes, but it may of course be used for connection of any other tube. The housing 1 of the coupling may be formed of metal, for instance brass. There is, however, no hindrance for forming the housing 1 of the coupling of another suitable material. The disc 12 for retaining of the clamping ring 4 and the adjacent gasket 5, possibly also including a support sleeve for supporting the tube 3 on the internal side, may as required be formed of another suitable material than plastic. The housing 1 of the coupling may be connected to another item, for instance another coupling housing, by means of a threaded connection or another suitable connection, and it may be sealed by a suitable gasket, for instance an 0-ring 15, as shown.

In the embodiment shown the tube coupling comprises a gasket 5 placed adjacent the clamping ring 4. It is, however, not necessary that the gasket 5 is included in the coupling, and it may be omitted in cases where only the gasket 14 in the end portion 8 having the smallest diameter is needed. Thereby, the clamping ring 4 will be in direct engagement with the outwardly bent portions or hooks 16 on the snap arms 10.