GB2277568A

GB2277568A - Fastening coupling for corrugated tubes

Info

Publication number: GB2277568A
Application number: GB9405954A
Authority: GB
Inventors: Jurgen Rumpel
Original assignee: REIKU GmbH
Current assignee: REIKU GmbH
Priority date: 1993-04-06
Filing date: 1994-03-25
Publication date: 1994-11-02
Anticipated expiration: 2014-03-25
Also published as: FR2703754B1; GB2277568B; DE4409837A1; GB9405954D0; CH689062A5; DE4409837C2; FR2703754A1

Abstract

A fastening coupling for corrugated tubes comprises a tubular sleeve (1) and a securing tongue (15) which is arranged movably in a recess (13) in the peripheral wall of the sleeve and is connected integrally with the sleeve via two lateral torsionally elastic webs (17). The securing tongue (15) is formed as a two-armed lever. One arm (15a) carries the locking projection (19) for engagement in a peripheral groove in the corrugated tube (21) and the other arm (15b) acts as a pressure plate for the pivoting of the securing tongue (15) into the release position. Each of the torsionally elastically webs (17) is of such a length that it is elastically resilient in the axial direction of the sleeve so that the securing tongue (15) can be displaced axially in the recess (13) and comes into contact with bevelled guide surfaces so formed that, when tension is applied to the coupled corrugated tube (21), the securing tongue is pressed more strongly inwards into the groove of the corrugated tube and/or that, when the corrugated tube is inserted, the locking projection (19) is pivoted outwards into the release position. <IMAGE>

Description

Fastening coupling for corrugated tubes The invention relates to a fastening coupling for corrugated tubes of the type indicated in the preamble of Claim 1. The fastening coupling can preferably be used as an adapter or screw joint for fastening corrugated insulation pipes to switch cabinets, housings, machines or the like.

A fastening coupling of this type is known from DE 39 03 353 Al. Its securing tongue is retained in the locked position by two lateral webs of material connecting it with the housing, in which position the locking projection protrudes into the unobstructed insert cross-section for the corrugated tube. By exerting pressure on the other arm of the securing tongue the locking projection can be moved radially outwards, under torsionally elastic deformation of the webs of material, so as to release the corrugated tube.

One disadvantage of the known coupling lies in the fact that the locking projection -is retained in the locking position exclusively by the elastic restoring force of the webs of material, so that a strong pull on the coupled corrugated tube can push the locking projection outwards and lead to unintentional release of the corrugated tube. To prevent this it would be possible for the webs to be of such dimensions that they offer a very powerful torsional resistance to the pivoting of the securing tongue. In this case, however, the coupling is very inaccessible both for coupling the corrugated tube and when it is desired to release the corrugated tube.

The invention is based on the object of developing a fastening coupling of the type indicated so that it has additional security against unintentional release of the coupled corrugated tube and/or it additionally facilitates the coupling of the corrugated tube.

The manner in which this object is achieved in accordance with the invention is indicated in Claims 1 and 2. The sub-claims refer to further advantageous developments of the invention.

Embodiments of the invention will now be illustrated with reference to the drawings, wherein: Figure 1 shows a fastening coupling according to a first embodiment of the invention, half in side view and half in longitudinal section; Figs. 2 and 3 show an end view and a plan view of the fastening coupling; Figure 4 shows a view corresponding to Figure 3 with a corrugated tube subject to tension; Figure 5 shows a detail of the fastening coupling in section; Figure 6 shows a modified embodiment of the fastening coupling, in a similar representation to Figure 1; Figure 7 shows a fastening coupling according to another embodiment of the invention, half in side view and half in longitudinal section; Figure 8 shows the fastening coupling of Figure 1 in side view in accordance with the viewing direction A in Figure 1; Figure 9 shows, on an enlarged scale, a partly sectional view along the line III-III in Figure 2.

The fastening coupling illustrated in Figures 1 to 3 comprises a substantially tubular sleeve 1 produced in one piece from plastics material, for example by injection moulding. At its end shown on the left in Figures 1 and 3, the sleeve 1 has a screw-threaded portion 3 with an external screw thread 5 so that the sleeve 1 can be screwed into an opening provided with an internal screw thread, for example in a housing wall 4 (see Figure 4). Flats 7 on the periphery of the sleeve 1 serve for the application of a screwing implement.

The portion of the sleeve 1 shown on the right in Figures 1 and 3 serves to accommodate a corrugated tube or corrugated hose 21 (Figure 4) which can be introduced through the open insertion end 9 of the sleeve as far as an inner abutment shoulder 11. At two mutually opposed locations a respective rectangular recess 13 is provided in the peripheral wall of the sleeve 1 delimiting the accommodating portion. In each recess 13 is disposed a securing tongue 15 which is produced integrally with the sleeve 1 and which approximately at its longitudinal centre is joined to the peripheral wall of the sleeve 1 via two bridges of material or webs 17. The securing tongue 15 is so formed that it almost completely fills up the wall opening 13 and between it and the rim of the opening 13 only a small clearance remains which is adequate for the freedom of movement of the securing tongue 15.

The two bridges of material or webs 17 serve as hinges which define a pivot axis which extends tangentially to the sleeve 1 and about which the securing tongue 15 can pivot to a limited extent, whereupon each web 17 is deformed in a torsionally elastic manner. On either side of the web 17 the securing tongue 15 is narrowed so that the web 17 is of sufficient length for the torsionally elastic deformation.

With respect to the pivot axis defined by the bridges of material or webs 17 the securing tongue 15 is in the form of a two-armed lever with two lever arms 15a and 15b. One lever arm 15a has on its inside a rib-like locking projection 19 for engagement in a peripheral groove in the corrugated tube to be fitted into the sleeve. The other arm 15b of the securing tongue 15 serves as a pressure plate. If this pressure plate 15b is pressed inwards by hand, the lever arm 15a moves outwards with the locking projection 19 so that the corrugated tube is released and can be removed from the sleeve 1.

The securing tongue 15 and the webs 17 are designed so that, in the relaxed, undeformed condition of the webs 17, the securing tongue 15 is situated in the locking position shown in Figure 1 and the locking projection 19 engages in the groove of the corrugated tube. In this locking position, the outer surface of the securing tongue 15 extends in alignment with the outer contour of the sleeve 1. When the lever arm 15b is pushed inwards the webs undergo torsionally elastic deformation so that, upon release of the lever arm 15b, the securing tongue 15 springs back into the locking position.

Each of the webs 17 is released by the delimiting constrictions or indentations of the securing tongue 15 along such a length that it is not only torsionally deformable but is also able to undergo bending deformation in a direction parallel to the axial direction of the coupling. As illustrated in the drawings, the length of each web 17, i.e. its extension transversely to the direction of the axis of the sleeve 1, is distinctly greater, preferably at least twice as large as its width parallel to the axis.

If, as illustrated in Figure 4, a tension is acting on a corrugated tube 21 fitted into the coupling, the securing tongue 15 can be displaced axially in the recess 13, whereupon the webs 17 are deformed in the manner indicated.

As a result of this displacement of the securing tongue 15 an abutment slope 23 formed at the end of the lever arm 15a comes into abutment with a peripheral web 25 of the sleeve 1 delimiting the recess 13. As a result of the co-operation of the abutment slope 23 with the peripheral web 25, the lever arm 15a is pressed inwards with the locking projection 19 so that the corrugated tube 21 is retained all the more securely as the tension increases.

Figure 5 shows, in an enlarged longitudinal section, the end of the securing tongue 15 with the abutment slope 23. The peripheral web 25 of the sleeve co-operating with the latter may also have a small bevel 27 on its inner edge.

An asymmetrically shaped locking projection 19 is also evident from-Figure 5, the end face of which facing the open end of the sleeve is turned away or bevelled so as to facilitate the insertion of the corrugated tube, whereas the other end face extends radially.

In the embodiment according to Figures 1 to 3, the lever arm 15a of the securing tongue 15 carrying the locking projection 19 is turned towards the open insertion end 9 of the sleeve. Figure 4 shows a modified embodiment in which the lever arm 15a provided with the locking projection 19 is directed away from the open insertion end 9 and towards the abutment shoulder 11. In conjunction with a corresponding configuration of the inclined surfaces of the locking projection 19 this arrangement has the advantage that any tension acting on the inserted corrugated tube exerts such torque on the securing tongue 15 that the locking projection 19 is pressed more firmly into the groove of the corrugated tube. Initially, this can be achieved by an inclined surface 23' at the end of the arm 15b, which is bevelled inwards and upon displacement of the securing tongue 15 abuts against the peripheral web 25.

The coupling may also be supplemented by a sealing ring which seals the end of the inserted corrugated hose against the sleeve 1. A sealing ring of this type may be provided particularly in the vicinity of the abutment shoulder 11 and may either be loosely inserted in the sleeve 1 or may be securely connected therewith. A sealing ring of this type is known to the person skilled in the art and, therefore, is not illustrated in the drawings.

The embodiment according to Figures 7 to 9 corresponds substantially to the embodiment described in the foregoing and the corresponding parts thereof, which are designed with the same reference numerals, will not be described again in the following.

In this embodiment a recess 31 is provided in the pressure plate 15b, in which recess an arm 33 is formed integrally which is directed rearwards in axial direction and has an inner projection 35 at its end. The inner projection 35 projects into the accommodating cross-section with a diameter Dn of the corrugated tube and is thus pressed outwards from the inserted corrugated tube end. A torque is generated thereby about the axis of rotation formed by the webs 17, said torque pressing the front arm 15a with the locking projection 19 into the groove of the corrugated tube.

As is evident from Figure 8, the arm 15a of the securing tongue 15 carrying the locking projection 19 is Tshaped in plan view so that it forms two rearwardly directed shoulders 37. These shoulders are situated opposite projections 39 which protrude inwards from the lateral walls of the recess 13 and which are each provided with an abutment slope 41 (Figure 9) which are directed towards the abutment shoulders 37. As is also evident from Figure 9, the locking projection 19 and the front end face of the arm 15a have a bevelled or rounded portion directed counter to the insertion direction.

During the insertion of the corrugated tube into the coupling, the end of the corrugated tube firstly abuts against the front end of the locking projection 19 and exerts thereon, and therefore on the securing tongue 15, a force which is directed both radially outwardly and axially.

The securing tongue 15 is thereby displaced axially rearwards under bending deformation of the webs of material 17, whereby the abutment shoulders 37 come into contact with the abutment slopes 41 of the projections 39 and pressed radially outwards thereby so that the locking projection 19 can deflect the corrugated tube, as indicated in dashed line in Figure 9. When the corrugated tube is fulled inserted, no more axial force is exerted on the securing tongue 15 and the latter is again pressed axially forwards by the restoring force of the webs of material 17, so that the abutment shoulders 37 are released from the projections 39 and the locking projection 19 can engage in a groove of the corrugated tube.

When tension is applied to the coupled corrugated tube, the securing tongue is moved axially forwards so that its front edge abuts against a slope 23 on the front boundary wall of the recess 13, whereby the locking projection is pressed more strongly radially inwards against the corrugated tube.

Modifications and developments of the embodiment described are possible within the scope of the invention. In particular, the number of securing tongues may be varied. It is also possible for the securing tongue to have two or more locking projections for engagement in adjacent grooves of the corrugated tube.

Claims

1. A fastening coupling for corrugated tubes, having a tubular sleeve of plastics material which has an open insertion end for accommodating the corrugated tube, and at least one securing tongue which is arranged movably in a recess in the peripheral wall of the sleeve and has a locking projection for engagement in a peripheral groove in the corrugated tube, the securing tongue being connected integrally with the sleeve via two lateral torsionally elastic webs and being pivotable about the pivot axis formed by the webs in such a way that the locking projection can be brought into a release position disengaged from the groove of the corrugated tube, and the securing tongue being formed as a two-armed lever, one arm of which carries the locking projection and the other arm of which forms a pressure plate for the pivoting of the securing tongue into the release position, wherein each web of material is elastically resilient in the axial direction of the sleeve so that the securing tongue can be displaced axially in the recess, and in that mutually opposed guide surfaces are formed on the securing tongue and on the sleeve, at least one of which surfaces is obliquely inclined with respect to the axial direction of the sleeve and which during displacement of the securing tongue, which is caused by tension applied to the corrugated tube, come into mutual abutment and generate a force pressing the locking projection inwards.

2. A fastening coupling for corrugated tubes, having a tubular sleeve of plastics material which has an open insertion end for accommodating the corrugated tube, and at least one securing tongue which is arranged movably in a recess in the peripheral wall of the sleeve and has a locking projection for engagement in a peripheral groove in the corrugated tube, the securing tongue being connected integrally with the sleeve via two lateral torsionally elastic webs and being pivotable about the pivot axis formed by the webs in such a way that the locking projection can be brought into a release position disengaged from the groove of the corrugated tube, and the securing tongue being formed as a two-armed lever, one arm of which carries the locking projection and the other arm of which forms a pressure plate for the pivoting of the securing tongue into the release position, wherein each web of material is elastically resilient in the axial direction -of the sleeve so that the securing tongue can be displaced axially in the recess, and in that mutually opposed guide surfaces are formed on the securing tongue and on the sleeve, at least one of which surfaces is obliquely inclined with respect to the axial direction of the sleeve and which during displacement of the securing tongue, which is caused by the compressive force during the insertion of the corrugated tube, come into mutual abutment and generate a force pressing the locking projection outwards.

3. A fastening coupling according to Claim 2, wherein the securing tongue has lateral indentations on either side of each web which leave each web free along the required length.

4. A fastening coupling according to any one of Claims 1 to 3, wherein the lever arm of the securing tongue carrying the locking projection is turned towards the open insertion end of the sleeve and has an outwardly bevelled abutment slope.

5. A fastening coupling according to any one of Claims 1 to 3, wherein the lever arm of the securing tongue forming the pressure plate is turned towards the open insertion end of the sleeve and has an inwardly bevelled abutment slope.

6. A fastening coupling according to any one of Claims 1 to 5, wherein a resilient arm with an inner projection is formed on the arm of the securing tongue forming the pressure plate, projects into the insertion cross-section for the corrugated tube and when the corrugated tube is inserted it abuts resiliently against the periphery thereof and generates a torque loading the locking projection into the locking position.

7. A fastening coupling according to Claim 1, wherein approximately at its longitudinal centre the securing tongue is joined to the peripheral wall of the sleeve by two material webs.

8. A fastening coupling according to Claim 2, wherein upon deflection of the securing tongue the webs are deformed in a torsionally elastic manner and exert a restoring force on the securing tongue in its locking position.

9. A fastening coupling according to any one of Claims 1 to 3, wherein the lever arm of the securing tongue carrying the locking projection is turned towards the open insertion end of the sleeve

10. A fastening coupling according to any one of Claims 1 to 3, wherein the lever arm of the securing tongue forming the pressure plate is turned towards the sleeve at the open insertion end.

11. A fastening coupling according to any one of Claims 1 to 5, wherein the outer surface of the securing tongue situated in the locking position extends flush with the outer contour of the sleeve.

12. A fastening coupling according to Claim 2, wherein the arm of the securing tongue carrying the locking projection has at least one abutment shoulder directed towards the other arm, and in that the sleeve has at least one projection protruding into the recess with an abutment slope against which the abutment shoulder abuts so as to generate the force pressing the locking projection outwards during the insertion of the corrugated tube.

13. A fastening coupling substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Amendments to the claims have been filed as follows 12. A fastening coupling according to Claim 1 or 2, wherein the arm of the securing tongue carrying the locking projection has at least one abutment shoulder directed towards the other arm, and in that the sleeve has at least one projection protruding into the recess with an abutment slope against which the abutment shoulder abuts so as to generate the force pressing the locking projection outwards during the insertion of the corrugated tube.