GB2102637A

GB2102637A - Cable gland connector with a safeguard against inadvertent loosening

Info

Publication number: GB2102637A
Application number: GB08220151A
Authority: GB
Inventors: Gunter Piewitt; Helmut Diehsner
Original assignee: Harting Electronics GmbH and Co KG
Current assignee: Harting Electronics GmbH and Co KG
Priority date: 1981-07-18
Filing date: 1982-07-12
Publication date: 1983-02-02
Also published as: DE3128541A1; FR2509920A1; FR2509920B1; GB2102637B; DE3128541C2

Abstract

A cable gland connector for line lead-ins on electrical appliances comprises a pressure applying member (12) which screws onto a cable inlet (3) to secure a cable (14) therein. Rotation of the tightened pressure member is prevented by sliding a sleeve (5) over the cable inlet so that a central recess (8) in the sleeve is pushed over a complementary projection (13) on the pressure member. The sleeve is held in this position, against axial displacement, by a crosspin (10) on a clamping ring (9) which engages a recess (7) on a rib 4 of the cable inlet. Inadvertent loosening of the connection is thus prevented. <IMAGE>

Description

SPECIFICATION Cable screw-connection with a safeguard against inadvertent loosening The invention relates to a cable screw-connection with a safeguard against inadvertent loosening, for line lead-ins on electrical appliances, such as, for example, for intrinsically safe, explosion-proof or moisture-proof equipment.

In the case of screw-connections of this type, which are usually designed as gland screw-connections, it is necessary to provide a safeguard which, during heavy-duty operation, prevents the cable screw-connection from being loosened as a result of rotary movements on the introduced cable and which prevent the leak-proofness (gas-tight, moisture-proof) achieved at the outset as a result of firm tightening of the gland from being vitiated.

To meet these requirements, it is known to use a two-part transversely split tension-relief clip on the screw-in pressure member of the gland screw-connection and, at the same time, to provide a finger-like projection on the releasable clip part, which, after the tensionrelief clip has been screwed together, engages into a recess in the fixed outer part of the gland and provides the safeguard against rotation.

On the whole, such a safeguard of the cable screw-connection meets the requirements to a satisfactory extent. However, the constructional dimensions of the known cable screwconnections are so large that they are scarcely suitable, -for example, for relatively small plugconnector housings with few pins. When the known safeguard for cable screw-connections is reduced correspondingly in size, however, it proves to be unstable and no longer provides the necessary durability during heavy-duty operation.

The object on which the invention is based is to provide a cable screw-connection with a safeguard against inadvertent loosening, which even during roughest operation, such as, for example, in underground mining equipment, has perfect protection against loosening, but which nevertheless has the smallest possible dimensions appropriate to the size of the plug-connector housings to be used.

This object is achieved, according to the invention, due to the fact that located on a nozzle, of the cable lead-in, on the housing side is an axially displaceable sliding sleeve which is secured against rotation and which is provided with a central recess which faces the pressure member of the gland screw-connection and which is made complementary to a non-circular projection shaped on the pressure member, it being possible to push the sliding sleeve at least partially over the projection and to fix said sleeve in this position against axial displacement.

Further advantageous designs of the cable screw-connection according to the invention are explained in Claims 2 to 10.

The advantages achieved by means of the invention are, in particular, that a cable screwconnection with a safeguard against inadvertent loosening, the constructional dimensions of which have been kept extremely small and which nevertheless withstand the roughest operating conditions, has been provided. At the same time, it is especially advantageous if, in a design in which the sliding sleeve is provided with a central hexagonal recess, gland pressure members provided with an outer hexagonal projection to permit application of a spanner to screw in the pressure member can still be used. Subsequent conversions of already existing screw-connections without a safeguard can be carried out without difficulty by the insertion of a simple and cheap intermediate nozzle which has the sliding sleeve including its device for safeguarding against axial displacement.At the same time, these screw-connections can be present both on cable lead-ins of plug-connector housings and on cable lead-ins of appliances.

The invention is described in more detail below with reference to an exemplary embodiment and the drawings which illustrate one embodiment only and in which: Figure 1 shows a view of a plug-connector housing with a safeguarded cable screw-connection, Figure 2 shows a view of the cable screwconnection before the individual parts are joined together, Figure 3 shows views of the sliding sleeve, Figure 4 shows views of the clamping ring with crosspin, Figure 5 shows a view of the gland pressure member according to Fig. 2 in a section along the line 5-5, Figure 6 shows a view of the nozzle on the housing side according to Fig. 2 in a section along the line 6-6, Figure 7 shows a view of a cable screwconnection in a housing wall with an intermediate nozzle, and Figure 8 shows views of the intermediate nozzle according to Fig. 7.

Figs. 1 and 2 show a plug-connector housing 1 with the cable screw-connection 2 secured against inadvertent loosening. The cable lead-in nozzle 3 on the housing side is provided with a sliding rib 4 extending in a longitudinal direction. The sliding sleeve 5 is provided with a complementary sliding groove 6 into which the sliding rib of the nozzle engages when the parts are joined together and which ensures that the sliding sleeve can be displaced only axially on the housing nozzle. Furthermore, these is provided in the sliding rib 4 the engagement recess 7, the purpose of which is explained in more detail below.

The sliding sleeve is provided at its upper end with a central hexagonal recess 8. Furthermore, the sliding sleeve has a snapped-on clamping ring 9 provided with the crosspin 10 which projects inwards through the lateral bore 11 in the sliding sleeve. To make it easier to handle the sliding sleeve, its outer surface is provided with lenurling 28.

The pressure member 1 2 of the gland screw-connection is provided at its end pointing towards the sliding sleeve with a hexagonal projection 1 3. This projection is, on the one hand, provided for applying a spanner when the pressure member is screwed in and, on the other hand, serves, together with the hexagonal recess in the sliding sleeve, for securing the pressure member against release (rotation), as explained in more detail below.

When the cable screw-connection is assembled the sliding sleeve 5 is first pushed completely onto the nozzle 3 on the housing side, that is to say beyond the subsequent engagement or locking position in which the securing crosspin 10 engages into the engagement recess 7. The pressure member 1 2 of the gland screw-connection is subsequently pushed over the cable 1 4 to be connected, and after the thrust washers 1 5 and the elastomeric sealing ring 1 6 have been inserted the cable is introduced into the lead-in orifice 1 7, provided with the bearing shoulder 29 for the sealing means, of the housing nozzle and is connected electrically to the plug-connector insert 1 8. The pressure member 1 2 is then screwed firmly into the housing nozzle, and the sealing ring 1 6 is compressed in a way known per se and pressed by means of its outer and inner surfaces firmly against the sealing face 1 9 in the housing nozzle and against the cable sheath 20 respectively, thereby sealing off the cable connection in a gas-tight and liquid-tight manner.

To safeguard the cable screw-connection against loosening, that is to say against rotation as a result of torsional forces occurring on the cable, the sliding sleeve 5 is subsequently pushed back on the housing nozzle until the hexagonal recess 8 engages round the hexagonal projection 1 3 of the pressure member 1 2 and the securing crossping 10 of the clamping ring 9 engages into the engagement recess 7 in the housing nozzle. It goes without saying that the pressure member has previously been rotated, during tightening, into such a position that the hexagonal projection of the pressure member and the hexagonal recess in the sliding sleeve are aligned with one another.

Since the sliding sleeve itself is secured against radial movement by the sliding rib 4 and the sliding groove 6 interacting therewith, the pressure member is now also no longer capable of executing rotary movements. The sliding sleeve is safely prevented from beinq pushed back out of its securing position by means of the crosspin 10 engaging into the engagement recess 7. At the same time, the clamping ring made of a resilient material ensures that the crosspin 10 is pressed firmly into this recess and can be removed only by means of a tooi, for example by levering the pin out by means of a screwdriver or the like pushed under the clamping ring in the vicinity of the crosspin.

Finally, the tension-relief clip 21 (axial relief of cable tension) is tightened firmly by means of the screws 22. Advantageously, the tension-relief device is made trumpet-shaped on the cable-outlet side so as to limit the radius of curvature of the connected cable and achieve perfect protection against kinking.

Fig. 7 illustrates an example where the cable screw-connection 2 is used on a housing wall 23. In many cases where cable screw-connections of this type are used, they are screwed into housing walls smooth per se and there is no cable iead-in nozzle 3 which can receive the sliding sleeve 5. Here, it is appropriate to use an intermediate nozzle 24 which is provided with the sliding rib 4 and the engagement recess 7. In this case the intermediate nozzle is provided with a thread 25 on the end face for screwing into the bore 27 in the housing wall. Furthermore, the axial passage through the intermediate nozzle is provided with the bearing shoulder 29' and the sealing face 19' for the sealing means 15, 1 6 of the gland screw-connection.Advantageously, the internal thread 26 of the gland screw-in connection is designed with the same nominal dimensions as the thread on the end face. As a result, an existing gland screwconnection provided with a hexagonal projection and hitherto screwed into the housing wall can subsequently be converted extremely cheaply, as a result of the insertion of the intermediate nozzle together with the sliding sleeve, into a cable screw-connection safeguarded against inadvertent loosening. In this design of the cable screw-connection with an intermediate nozzle, it is merely necessary to ensure that the intermediate nozzle screwed into the housing wall is connected to this unreleasably (in a rotation-proof manner). This can be carried out, for example by fixing the thread by means of adhesive material or the like introduced into the thread pitches during screwing-in.

It should be pointed out once again, here, that a cable screw-connection constructed in accordance with the above particulars can be used not only on housing walls, but, with an appropriate design of the screw-in thread, on any screw-in cable screw-connections (plugconnector housings, etc.).

The sliding sleeve 5 can be fixed against axial displacement not only by means of a crosspin 10 fastened to a clamping ring 9, as described in the statements set outabove. but it is also possible just as easily, and within the scope of the invention, to provide, to secure the position of the sliding sleeve, a stud bolt which is screwed through its bore 11 into the recess 7 in the nozzle 3. It is conceivable just as easily to design this safeguard as a ball catch, in which case, for example, the end of the crosspin is made hemispherical and the engagement recess is designed as a ball impression.

A further possibility for axial fixing of position is afforded by shaping in the nozzle 3 an annular groove into which a spring ring or the like, which positively prevents the sliding sleeve 5 from the slipping back, is engaged after the sliding sleeve has been displaced into its securing position.

In so far as the known state of the art so permits, all the feature mentioned in the foregoing description and/or illustrated in the drawing are to be considered as essential to the invention in themselves or in any combinations or partial combinations, even when they are not contained in the claims.

Claims

1. Cable screw-connection with a safeguard against inadvertent loosening, for line lead-ins on electrical appliances, such as, for example, for intrinsically safe, explosion-proof or moisture-proof equipment, wherein located on a nozzle (3), of the cable lead-in, on the housing side is an axially displaceable sliding sleeve (5) which is secured against rotation and which is provided with a central recess (8) which faces the pressure member (12) of the gland screw-connection and which is made complementary to a non-circular projection (13) shaped on the pressure member, it being possible to push the sliding sleeve at least partially over the projection and to fix said sleeve in this position against axial displacement.

2. Cable screw-connection according to Claim 1, wherein the safeguard of the sliding sleeve (5) against rotation is designed as a tongue(4)/groove(6) connection.

3. Cable screw-connection according to Claim 1, wherein the safeguard of the sliding sleeve against rotation is provided by a nozzle (3), on the housing side, which has an angular or oval, generally non-circular cross-section.

4. Cable screw-connection according to Claim 1 or the following claims, wheren the projection (13) of the pressure member (12) is designed as a hexagon, and the recess (8), of the sliding sleeve, which can be pushed over this projection is likewise designed as a hexagon matching the width across flats of the projection.

5. Cable screw-connection according to Claim 1 or the following claims, wherein the sliding (5) is safeguarded agaist axial displacement, in its securing position, by a clamping ring (9) provided with a crosspin (10), the crosspin engaging into a corresponding engagement recess (7) in the nozzle (3) on the housing side.

6. Cable screw-connection according to Claim 1 or the following claims, wherein the sliding sleeve is safe guarded against axial displacement, in its securing position, by a transverse screw which can be screwed into a recess (7) in the nozzle on the housing side.

7. Cable screw-connection according to Claim 6, wherein the sliding sleeve is safeguarded against axial displacement, in its securing position, by a transverse screw which is provided with a tip which can be pressed into the material of the nozzle on the housing side of the pressure member projection.

8. Cable screw-connection according to Claim 1 or the following claims, wherein the sliding sleeve (5) is safeguarded against axial displacement, in its securing position, by a retaining ring snapped into a groove in the nozzle (3) on the housing side.

9. Cable screw-connection according to Claim 1 or the following claims, wherein the sliding sleeve is safeguarded against axial displacement, in its securing position, by a ball catch.

1 0. Cable screw-connection according to Claim 1 or the following claims, wherein the sliding sleeve (5) is located on an intermediate nozzle (24) which can be screwed into a housing bore (27).