AU2011214879B2

AU2011214879B2 - Connection device for a plastic tube

Info

Publication number: AU2011214879B2
Application number: AU2011214879A
Authority: AU
Inventors: Elmar Ratschmann
Original assignee: Ke Kelit Kunststoffwerk GmbH
Current assignee: Ke Kelit Kunststoffwerk GmbH
Priority date: 2010-02-10
Filing date: 2011-01-14
Publication date: 2015-07-23
Anticipated expiration: 2031-01-14
Also published as: EP2534401B1; CN102472422B; AR080016A1; ES2445544T3; HK1167701A1; EP2534401A1; AU2011214879A1; SG182244A1; NZ596050A; MY163464A; AT508668A4; AT508668B1; WO2011097659A1; DK2534401T3; CN102472422A

Abstract

The invention relates to a connection device for a plastic tube (1), comprising a connection nipple (2) that receives the plastic tube (1) and forms an outer cone (6) widening towards the free nipple end. An expansion ring (5) that can be slid over the outer cone (6) and comprises outwardly protruding retaining claws (7) is provided between the outer cone and an axial abutment (11), said expansion ring being supported on the axial abutment (11) of the connection nipple (2) by means of a supporting ring (9). Said device also comprises a sleeve (4) surrounding the plastic tube (1) that has been pushed onto the connection nipple (3) and gripping in a traction-resistant manner onto an abutment flange (3) of the connection nipple. In order to create advantageous assembly conditions, a rubber-elastic spring ring (8) is arranged between the expansion ring (5) and the supporting ring (9). The expansion ring (5), the supporting ring (10) and the spring ring (8) are interconnected in a shear-resistant manner.

Description

Connection device for a plastic tube 1. Field of the Invention The invention relates to a connection device for a plastic tube, having a con nection nipple which receives the plastic tube, and which forms an outer cone expanding toward the free nipple end, between which and an axial stop, a spreading ring, which can be pushed onto the outer cone, having outwardly protruding retaining claws is provided, which is supported via a support ring on the axial stop of the connection nipple, and having a sleeve, which engages in a tension-resistant manner on a stop flange of the connection nipple and en closes the plastic tube pushed onto the connection nipple. 2. Description of the Prior Art In a known connection device of this type (AT 410 706 B), the plastic tube is pushed onto a connection nipple, which carries a spreading ring having out wardly protruding retaining claws in the area of an outer cone, so that when the plastic tube is pushed on, it slides over the spreading ring located in the ta pered area of the outer cone. Upon an attempt to pull the plastic tube off of the connection means, the spreading ring is carried along the via its protruding re taining claws and pushed onto the outer cone. The spreading of the spreading ring connected thereto causes fixing of the plastic tube, which is enclosed by a tension-resistant sleeve connected to a stop flange of the connection nipple, so that the plastic tube cannot evade the spread spreading ring and is fixed be tween the spreading ring and the sleeve, which acts as a counter bearing. In order to be able to compensate for stretching of the plastic tube, a free dis- -2 placement path is preferably provided for the spreading ring. Since the spreading ring having its retaining claws is to be within the outer circumference of the connection nipple as much as possible for simple pushing of the plastic tube onto the connection nipple, the danger exists that when the plastic tube is pulled off of the connection nipple, the spreading ring will not be carried along and therefore also will not be pushed onto the outer cone of the connection nipple. In such a case, the plastic tube therefore cannot be fixed between spreading ring and sleeve. In order to avoid this, supporting the spreading ring via a rubber-elastic support ring on the axial stop of the connection nipple has already been proposed (AT 504 370 Al). However, this design has several disadvantages with respect to its functionality. Thus, not only is the assembly complex, but rather also the danger exists that when the plastic tube is pushed onto the connection nipple, the rubber-elastic support ring will be forced out of its receptacle groove in the gap between connection nipple and sleeve and pushed along the connection nipple, which impairs the spring function of the support ring, whereby a defined contact pressure force for the retaining claws placed against the tube interior is no longer ensured. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application. SUMMARY OF THE INVENTION Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. In a first aspect, the present invention provides a connection device for a plastic tube, having a connection nipple, which receives the plastic tube and forms an outer cone expanding toward the free nipple end, between which and an axial stop a spreading ring having outwardly protruding retaining claws, which can be pushed onto the outer cone, is provided, which is supported via a support ring on the axial stop of the -3 connection nipple, and having a sleeve, which engages on a stop flange of the connection nipple in a tension-resistant manner and encloses the plastic tube pushed onto the connection nipple, wherein a rubber-elastic spring ring is situated between spreading ring and support ring, with spreading ring, support ring, and spring ring being connected to one another in a shear-resistant manner. Embodiments of the invention may be based on designing a connection device of the type described at the beginning so that secure fixing of the plastic tube between the spreading ring and the sleeve having a secured contact pressure force for the retaining claws can be ensured using simple structural means, without having to dispense with pushing the plastic tube onto the connection nipple using comparatively little force. In addition, the assembly conditions may be simplified. Embodiments of the invention may provide a rubber-elastic spring ring situated between spreading ring and support ring, spreading ring, support ring, and spring ring being connected to one another in a shear-resistant manner. Through the springy support of the spreading ring on the stop of the connection nipple in the axial direction, the spreading ring can be pushed at least far enough off of the outer cone by the plastic tube against the spring force of the support as the plastic tube is pushed onto the connection nipple so that the spreading ring comes to rest essentially inside the nipple circumference and therefore does not represent an increased pushing resistance for the plastic tube. The spreading ring is supported via the rubber-elastic spring ring and the support ring, which presses against the stop of the connection nipple, spreading ring, spring ring, and support ring forming a shear resistant composite body, which can be placed jointly on the outer cone or removed therefrom. Since the spreading and support rings, which are manufactured from a rigid, non-rubber elastic material, such as a hard plastic, a metal, or a material having a similar effect in relation to the spring ring, receive the spring ring between them in a shear-resistant manner, displacement of the spring ring from its receptacle groove in the gap between connection nipple and sleeve when the plastic tube is pushed onto the connection nipple is also reliably prevented, whereby a defined contact pressure force of the retaining claws against the tube interior is always ensured. Upon an - 3A attempt is made to pull the plastic tube off of the connection nipple, the spring ring acting in the axial direction supports the pushing of the spreading ring onto the outer cone, whereby the correspondingly protruding retaining claws force reliable carrying along of the spreading ring with-the plastic tube, with the consequence that the clamping forces acting on the plastic tube between the spreading ring and the sleeve become greater with increasing withdrawal. The design and assembly is less complex, since only one component is to be inserted into the receptacle groove implemented by the outer cone and the stop.

-4 If the support ring and the spring ring are implemented as slotted like the spreading ring, particularly simple assembly of the module can be ensured. In correct assemblies can additionally be practically precluded by the shear resistant composite. If the rubber-elastic spring ring additionally has a variable thickness in the axial direction, a positive influence on the deformation tenden cy of the spring ring as the plastic tube is pushed onto the spreading ring can additionally be taken by appropriate adaptation and selection of this geometry, in order to reduce still further the clamping tendency of the spring ring between connection nipple and tube. For fine tuning, or to be able to avoid excess bulges of the spring ring as the plastic tube is pushed on, the possibility additionally exists of situating two or more rubber-elastic spring rings alternately between spreading ring and support ring, between which optionally a further support ring may be situated in each case, whereby an alternating arrangement of spring rings and support rings re sults. In order to avoid radial yielding of spreading ring, spring ring, and support ring as the plastic tube is pushed onto the connection nipple, it is suggested that the support ring engage in an undercut groove associated with the stop flange us ing its front face facing toward the stop flange. The front face of the support ring facing toward the stop flange preferably has a geometry adapted to the groove shape. BRIEF DESCRIPTION OF THE DRAWING The object of the invention is shown for exemplary purposes in the drawing. In the figures: Figure 1 shows a connection device according to the invention for a plastic tube in a simplified axial section, -5 Figure 2 shows a detail from Figure 1, which shows the spreading ring, in an enlarged scale, and Figure 3 shows a device from Figure 2 having a design variant of a spreading ring according to the invention, Figure 4 shows a spreading ring according to the invention in a diagonal view, and Figure 5 shows a design variant of the device from Figure 1 in a simplified ax ial section. DESCRIPTION OF THE PREFERRED EMBODIMENT According to Figure 1, the connection device for a plastic tube 1, indicated by dot-dash lines, has a connection nipple 2, which receives the plastic tube 1, having a stop flange 3, on which the sleeve 4 enclosing the plastic tube 1 en gages in a tension-resistant manner. In order to clamp the plastic tube 1 between the connection nipple 2 and the sleeve 4, a spreading ring 5 is mounted on the connection nipple 2, which co operates with an outer cone 6 of the connection nipple 2. The arrangement is made so that the spreading ring 5, which forms radially protruding retaining claws 7 on the outer side facing toward the plastic tube 1, is supported in a springy manner via a rubber-elastic spring ring 8 and a support ring 9 on a stop 11 of the connection nipple 2. Spreading ring 5, spring ring 8, and support ring 9 form a module made of individual parts assembled in a shear-resistant man ner. If the plastic tube 1 is pushed onto the connection nipple 2, the spreading ring 5 can be pushed onto the outer cone 6 against the spring force of the rubber elastic spring ring 8 enough that the spreading ring 5 comes to rest essentially inside the circumference of the connection nipple 2, so that the plastic tube 1 can be pushed without special application of force beyond the spreading ring 5 until it stops on the stop flange 3. Upon an attempt to pull the plastic tube 1 off -6 of this fastening position from the connection nipple 2, the spreading ring 5, supported by the rubber-elastic spring ring 8, is pushed onto the outer cone 8 and spread open, whereby the retaining claws 9 increasingly press into the in ner wall of the plastic tube 1 and thus produce a form fit, which only allows the plastic tube 1 to be pulled further off of the connection nipple 2 while carrying along the spreading ring 5. This means that the plastic tube 1 is increasingly clamped between the sleeve 4 and the spreading ring 5 and fixed against fur ther pulling off. The seal between the plastic tube 1 and the connection nipple 2 is typically achieved via sealing rings 10, which are inserted into receptacle grooves of the connection nipple 2. Particularly simple assembly of the module is ensured in that the support ring 9 and the spring ring 8, like the spreading ring 5, have an axial spreading slot B. The shear-resistant composite additionally has the result that incorrect assem blies are practically precluded. If the rubber-elastic spring ring 8 additionally has a varying thickness in the axial direction, for example, constrictions be tween thickness maxima in the illustrated exemplary embodiment, positive in fluence can be taken on the deformation tendency of the spring ring as the plastic tube 1 is pushed onto the spreading ring 5 by appropriate adaptation and selection of this geometry. For fine tuning, or to avoid excess bulges of the spring ring as the plastic tube 1 is pushed on, two or more rubber-elastic spring rings 8 may be situated be tween spreading ring 5 and support ring 9, between each of which a further support ring 9 is preferably situated, whereby spring rings 8 and support rings 9 are alternately situated after the spreading ring 5 (Figure 3). In order to prevent radial yielding of spreading ring 5, spring ring 8, and support ring 9 as the plastic tube 1 is pushed onto the connection nipple 2, it is recom mended that the support ring 9 engage in an undercut groove 11 assigned to the stop flange 3 using its front face facing toward the stop flange 3. The front face of the support ring 9 facing toward the stop flange 3 has a geometry -7 adapted to the groove shape in the illustrated exemplary embodiment accord ing to Figure 5, i.e., it forms a matching counterpart. As the plastic tube 1 is pushed onto the connection nipple 2, the support ring 9 is inserted using its terminal attachment into the undercut groove 11 and secured against radial breakout.

Claims

1. A connection device for a plastic tube, having a connection nipple, which receives the plastic tube and forms an outer cone expanding toward the free nipple end, between which and an axial stop a spreading ring having outwardly protruding retaining claws, which can be pushed onto the outer cone, is provided, the spreading ring being supported via a support ring on the axial stop of the connection nipple, and having a sleeve, which engages on a stop flange of the connection nipple in a tension resistant manner and encloses the plastic tube pushed onto the connection nipple, wherein a rubber-elastic spring ring is situated between spreading ring and support ring, with spreading ring, support ring, and spring ring being connected to one another in a shear-resistant manner.

2. The connection device according to Claim 1, wherein the support ring, the spring ring and/or the spreading ring have an axial spreading slot.

3. The connection device according to Claim 1 or 2, wherein the rubber-elastic spring ring is equipped with varying thicknesses in the axial direction.

4. The connection device according to Claim 3, wherein the varying thicknesses in the axial direction are constrictions between thickness maxima.

5. The connection device according to Claim 3, wherein the rubber-elastic spring ring is in the form of a corrugated tube.

6. The connection device according to any one of Claims 1 to 5, wherein two or more rubber-elastic spring rings are situated between the spreading ring and the support ring.

7. The connection device according to Claim 6, wherein a further support ring is situated between the two or more rubber-elastic spring rings. -9

8. The connection device according to any one of Claims 1 to 7, wherein the support ring engages in an undercut groove associated with the stop flange using its front face facing toward the stop flange.

9. The connection device according to Claim 8, wherein the front face of the support ring facing toward the stop flange has a geometry adapted to the groove shape.

10. A connection device for a plastic tube, substantially as hereinbefore described with reference to the drawings.