Electrical plug connectors are known in various configurations. There are plug connectors which are provided to be arranged at one end of an electrical conductor. To this end, there is fitted at the end of the electrical conductor an electrically conductive contact element which is subsequently inserted into the plug connector and which is secured against being inadvertently removed by means of a nut. However, it has been found that such a nut can become loose independently over time, for example, owing to external vibrations, whereby undesirable disengagement of the contact element from the plug connector may occur. In the past, attempts have been made to prevent this problem by adhesively bonding the screwed nut to the plug connector. However, this method has the disadvantage that it is no longer possible to remove the nut as necessary for repair or maintenance purposes without it being destroyed.

An object of the present invention is therefore to provide an improved electrical plug connector. This object is achieved by an electrical plug connector having the features of claim 1. Preferred developments are set out in the dependent claims.

An electrical plug connector according to the invention comprises a plug connector housing and a nut. The plug connector housing has an external thread having a first thread pitch and the nut has an internal thread having a second thread pitch. The external thread further has a first web which is arranged substantially perpendicularly relative to the extension direction of the first thread pitch in the first thread pitch between two adjacent first flanks of the external thread. Furthermore, the internal thread has a first groove which is arranged substantially perpendicularly relative to the extension direction of the second thread pitch in a second flank of the internal thread. Advantageously, in this electrical plug connector, the groove of the internal thread and the web of the external thread can engage with each other so that the nut is secured against rotation and consequently against becoming inadvertently disengaged from the plug connector housing. Another advantage is that the nut can nonetheless be disengaged from the plug connector housing if necessary without the nut or the plug connector housing becoming damaged. Preferably, a height of the first web with respect to the first thread pitch is smaller than a height of the first flanks. Advantageously, the guiding properties of the external thread are thereby maintained so that the nut can readily be screwed on.

In a particularly preferred manner, the first web extends over a plurality of adjacent portions of the first thread pitch. Advantageously, a retention force with which the web secures the nut against undesirable rotation is thereby increased.

In a development of the electrical plug connector, the external thread has a second web which is arranged at a side of the external thread radially opposite the first web.

Advantageously, the provision of a second web increases the retention force with which the nut is secured against undesirable rotation.

Preferably, a depth of the first groove is smaller than a depth of the second thread pitch. Advantageously, the internal thread then retains its guiding properties which allows the nut to be readily screwed onto the plug connector housing.

Preferably, the first groove extends over a plurality of adjacent second flanks.

Advantageously, a retention force with which the nut is secured against undesirable rotation is thereby increased.

In a development of the electrical plug connector, the internal thread has a second groove. Advantageously, the nut can then take up various angular positions on the plug connector housing, the nut being secured against undesirable rotation in each of the angular positions.

In a particularly preferred configuration of the electrical plug connector, the internal thread has six grooves which are arranged so as to be distributed in the peripheral direction of the internal thread. Advantageously, it has been found in experiments that a number of six grooves constitutes a particularly favourable compromise between flexible positionability of the nut on the plug connector housing and guiding of the nut on the plug connector housing brought about by the remaining internal thread. It is advantageous for the first web to have a cross-section in the form of a circle segment having a first radius. Advantageously, such a shape of the web makes it easier to screw the nut onto the plug connector housing since the second flanks of the internal thread can then slide more easily over the first web.

It is also advantageous for the first groove to have a cross-section in the form of a circle segment having a second radius. Advantageously, this also makes it easier to screw the nut onto the plug connector housing since the first web of the external thread can then slide more easily out of the first groove.

In a particularly preferred manner, the second radius is greater than the first radius.

Advantageously, production tolerances in the production of the nut and the plug connector housing can then be compensated for. Furthermore, it is easier to slide the web out of the groove when the radius of the groove is greater than the radius of the web.

Preferably, the plug connector housing comprises a plastics material. Advantageously, the plug connector housing can then be produced in a cost-effective manner.

It is also preferable for the nut to comprise a plastics material. Advantageously, the nut can then also be produced in a cost-effective manner. Furthermore, plastics material has advantageous resilient properties which make it easier to screw the nut onto the plug connector housing.

The invention is explained in greater detail below with reference to Figures, in which: Figure 1 is a perspective view of a plug connector housing of a plug connector;

Figure 2 is a perspective view of a nut of the plug connector;

Figure 3 is a cross-section of the plug connector with the plug connector housing and the nut screwed on;

Figure 4 is a detail of the plug connector housing and the nut screwed on; and

Figure 5 is another cross-section of the plug connector housing with the nut screwed on. Figure 1 is a perspective view of a plug connector housing 200 of an electrical plug connector 100. The plug connector 100 can be used to produce an electrical connection, for example, to produce an electrical connection in a solar installation.

To this end, the plug connector housing 200 has a cable side 202 at which an electrical conductor can be introduced into the plug connector housing 200 in order to produce an electrical connection between the electrical conductor and contact elements arranged inside the plug connector housing 200. Furthermore, the plug connector housing 200 has an insertion side 201 which is opposite the cable side 202 and which is provided to be joined together with a plug connector counter-piece which fits the plug connector 100 in order to produce an electrical connection between the contact elements arranged in the plug connector housing 200 and contact elements of the plug connector counter-piece.

In the configuration of the plug connector 100 illustrated in Figure 1, the plug connector housing 200 has a substantially cylindrical shape. The precise configuration of the plug connector housing 200 and in particular the configuration of the insertion side 201 of the plug connector housing 200 is, however, not limited to the construction illustrated. Instead, the plug connector housing 200 can be constructed differently in accordance with the provided application of the plug connector 100. In particular, the insertion side 201 of the plug connector housing 200 may have different configurations depending on the application provided and the configuration of the associated plug connector counter-piece.

The cable side 202 of the plug connector housing 200 has an opening which is parallel with the longitudinal axis of the plug connector housing 200 and through which an electrical conductor which is provided with a contact element can be inserted into the plug connector housing 200. To this end, the insulation is removed from an end portion of the electrical conductor and the end portion is connected to the contact element, for example, by means of crimping. Subsequently, the end of the electrical conductor provided with the contact element is introduced from the cable side 202 of the plug connector housing 200 into the plug connector housing 200, whereby an electrically conductive connection is produced between the electrical conductor and other contact elements provided in the plug connector housing 200. In order to prevent the electrical conductor which is arranged in the plug connector housing 200 from being inadvertently removed from the plug connector housing 200, the electrical conductor is secured by means of a nut 300 which is illustrated as a perspective view in Figure 2. To this end, the cable side 202 of the plug connector housing 200 has a cylindrical region which forms a thread core 220 and which is provided with an external thread 210. The external thread 210 has a first thread pitch 230 which extends as a helical line between first flanks 240. The external thread 210 may be a right-hand thread or a left- hand thread. The first flanks 240 and the first thread pitch 230 of the external thread 210 may be constructed as an angular thread, trapezoidal thread, buttress thread, round thread or as any other thread.

The nut 300 has a substantially hollow-cylindrical shape and is provided with an internal thread 310. The internal thread 310 has a second thread pitch 330 which extends along a helical line between second flanks 340. The internal thread 310 is constructed and sized in such a manner that it can be screwed to the external thread 210 of the plug connector housing 200.

At the side opposite the internal thread 310, the nut 300 has a guide passage 301 which is constructed as a through-opening and through which the electrical conductor which is intended to be connected to the plug connector 100 is guided. When the plug connector 100 is mounted, the electrical conductor with the contact element secured thereon is first guided through the guide passage 301 of the nut 300, the contact element is subsequently inserted from the cable side 202 of the plug connector housing 200 into the plug connector housing 200 and the conductor is subsequently secured in the plug connector housing 200 by the nut 300 being screwed onto the plug connector housing 200.

In order to prevent the nut 300 from becoming inadvertently disengaged from the plug connector housing 200, the nut 300 must be secured against inadvertent rotation relative to the plug connector housing 200. To this end, the external thread 210 of the plug connector housing 200 and the internal thread 310 of the nut 300 have a catch device which acts as a rotation prevention mechanism. The external thread 210 of the plug connector housing 200 is provided with a first web 250 which is orientated parallel with the longitudinal axis of the plug connector housing 200 and consequently substantially perpendicularly relative to the extension direction of the first thread pitch 230 and the first flanks 240. The web 250 extends from an inner end of the external thread 210 facing the insertion side 201 of the plug connector housing 200 in the direction of an outer end of the external thread 210 facing the cable side 202 of the plug connector housing 200. The length of the first web 250 is such that the first web 250 does not reach the outer end of the external thread 210 facing the cable side 202. In the example illustrated in the Figure, the first web 250 comprises a first web portion 251, a second web portion 252 and a third web portion 253. Each of the web portions 251, 252, 253 is arranged in a portion of the first thread pitch 230 between two mutually adjacent first flanks 240 of the external thread 210. Consequently, the first web 250 extends from the inner end of the external thread 210 over three mutually adjacent portions of the first thread pitch 230 via two intermediate portions of the first flanks 240.

At the side of the external thread 210 opposite the first web 250 in the radial direction of the external thread 210, the external thread 210 has a second web 260 which is constructed in the same manner as the first web 250. The second web 260 cannot be seen in Figure 1.

The internal thread 310 of the nut 300 has a first groove 350 which extends from the outer end of the internal thread 310 facing away from the guide passage 301 of the nut 300 in the direction of the inner end of the internal thread 310 facing the guide passage 301. The first groove 350 is constructed as a channel-like indentation or recess in mutually adjacent portions of the second flanks 340 of the internal thread 310. In the embodiment illustrated in Figure 2, the first groove 350 comprises a first groove portion 351, a second groove portion 352 and a third groove portion 353. The first groove 350 consequently extends from the outer end of the internal thread 310 over three successive portions of the second flanks 340.

In the configuration of the nut 300 illustrated in Figure 2, the internal thread 310 further has a second groove 360, a third groove 361, a fourth groove 362, a fifth groove 363 and a sixth groove 364. The grooves 350, 360, 361, 362, 363, 364 are distributed in the peripheral direction of the internal thread 310 with uniform mutual angular spacing. In the illustrated embodiment of an internal thread 310 with six grooves 350, 360, 361, 362, 363, 364, two mutually adjacent grooves consequently have an angular spacing of

approximately 60°.

Figure 3 is a cross-section, which extends parallel with the longitudinal axis of the plug connector housing 200 through the first web 250 and the second web 260, of the plug connector 100 with the plug connector housing 200 and the nut 300 which is screwed onto the plug connector housing 200. It can be seen that the first web 250 is arranged and engaged in the region of the first groove 350 and the second web 260 in the region of the fourth groove 362. The nut 300 is thereby secured against being inadvertently rotated relative to the plug connector housing 200. Inadvertent removal of the nut 300 from the plug connector housing 200 and consequently also inadvertent removal of the electrical conductor which is not illustrated in Figure 3 and which is arranged in the plug connector housing 200 is thereby prevented.

Figure 4 is an enlarged illustration of the region of the first web 250 and the first groove 350 illustrated in Figure 3. It can be seen that, from the inner end of the external thread 210, web portions 251, 252, 253 of the first web 250 are arranged in the first three portions of the first thread pitch 230. The height of the web 250 in the direction perpendicular relative to the longitudinal axis of the plug connector housing 200 and substantially perpendicular relative to the extension direction of the first thread pitch 230 is slightly smaller than the height of the first flanks 240. Consequently, the first flanks 240 also still protrude in the region of the first web 250 slightly beyond the first web 250. This is advantageous since the guiding properties of the external thread 210 are thereby also maintained in the region of the first web 250. However, the first web 250 could also have a different height.

It can further be seen in Figure 4 that, in the illustrated portion of the internal thread 310 of the nut 300 from the outer end of the internal thread 310, the first groove portion 351, the second groove portion 352 and the third groove portion 353 of the first groove 350 extend through the first three mutually adjacent portions of the second flanks 340 of the internal thread 310. The depth of the first groove 350 is slightly smaller than the depth of the second thread pitch 230 of the internal thread 310. Consequently, there also remain in the region of the first groove 350 remaining portions of the second flanks 340 which protrude beyond the second thread pitch 330. This is advantageous since the guiding properties of the internal thread 310 are thereby also maintained in the region of the first groove 350. However, the first groove 350 could also have a different depth.

Figure 5 is a cross-section of the plug connector 100 with the plug connector housing 200 and the nut 300 screwed onto the plug connector housing 200 along the line of section A-A illustrated in Figure 3. In Figure 5, it is possible to see the first web 250 which is engaged in the region of the first groove 350. Furthermore, the second groove 360 can be seen, no web of the external thread 210 being arranged in the region of the second groove 360. Figure 5 illustrates that the first web 250 has a cross-section in the form of a circle segment having a first radius. The first groove 350 and the second groove 360 have cross-sections in the form of a circle segment having a second radius. The second radius is greater than the first radius. Furthermore, the centre point of the circle segment having the second radius is located closer to the longitudinal axis of the plug connector housing 200 than the centre point of the circle segment having the first radius. Consequently, the first web 250 in the extension direction of the first thread pitch 230 of the external thread 210 has steeper flanks than the first groove 350. This makes it easier to screw the nut 300 on and off the plug connector housing 200 since the less steep flanks of the first groove 350 make sliding over the first web 250 easier.

The nut 300 is first screwed onto the plug connector housing 200 in conventional manner. However, as soon as the outermost portion of the second flank 340 of the internal thread 310 of the nut 300 strikes one of the webs 250, 260 of the external thread 210, a resistance is produced which prevents the nut 300 from being screwed further onto the plug connector housing 200. However, with the application of a given force, the nut 300 is screwed on further, the internal thread 310 of the nut 300 and the external thread 210 of the plug connector housing 200 readily being resiliency deformed so that the second flank 340 of the internal thread 310 of the nut 300 is raised over the web 250, 260 of the external thread 210. This is facilitated by the cross-section of the webs 250, 260 in the form of a circle segment.

After further rotation of the nut 300 through a specific angle, one of the grooves 350, 360, 361, 362, 363, 364 reaches one of the webs 250, 260, whereby the respective web 250, 260 is engaged in the respective groove 350, 360, 361, 362, 363, 364. However, with a light application of force, the nut 300 is further rotated whereby, with a degree of resilient deformation of the internal thread 310 and the external thread 210, the second flank 340 of the internal thread 310 is again raised over the respective web 250, 260. This is supported by the circle- segment- like cross-sections of the webs 250, 260 and the grooves 350, 360,

361, 362, 363, 364.

The procedure described is continued until the nut 300 has been screwed sufficiently far onto the plug connector housing 200 and the webs 250, 260 are engaged in grooves 350, 360, 361, 362, 363, 364. In this state, the nut 300 is secured against becoming

inadvertently disengaged from the plug connector housing 200. Only with increased application of force can the nut 300 be unscrewed from the plug connector housing 200.

The number of two webs 250, 260 on the external thread 210 of the plug connector housing 200 and the number of six grooves 350, 360, 361, 362, 363, 364 in the internal thread 310 of the nut 300 has been found to be particularly advantageous. The two webs 250, 260 bring about adequate retention force to prevent the nut 300 from becoming inadvertently disengaged. The six grooves 350, 360, 361, 362, 363, 364 allow flexible angular adjustment of the nut 300 in steps of 60°, but leave sufficiently large portions of the second flanks 340 of the internal thread 310 intact in order to ensure reliable guiding of the internal thread 310 on the external thread 210. However, it is also possible to provide a different number of webs and grooves.

The length of the webs 250, 260 and the grooves 350, 360, 361, 362, 363, 364 may also be selected to be different from that in the embodiment illustrated. In the configuration illustrated, the webs 250, 260 extend in each case in three web portions 251, 252, 253 over three adjacent portions of the first thread pitch 230. The grooves 350, 360, 361, 362, 363, 364 each extend in three groove portions 351, 352, 253 over three mutually adjacent portions of the second flanks 340 of the internal thread 310. A higher retention force of the engagement and consequently even more effective securing of the nut 300 against inadvertent rotation may be achieved by the webs 250, 260 and the grooves 350, 360, 361,

362, 363, 364 being extended in such a manner that they extend over more than three adjacent portions of the first thread pitch 230 of the external thread 210 and the second flanks 340 of the internal thread 310.

The cross-sections of the webs 250, 260 and the grooves 350, 360, 361, 362, 363, 364 may also be selected to have a shape other than a sector of a circle, for example, a triangular shape.

The plug connector housing 200 and the nut 300 preferably comprise a plastics material. This has the advantage that the plug connector housing 200 and the nut 300 can then be produced in a cost-effective manner by means of an injection-moulding method. The external thread 210 and the internal thread 310 can already be produced during the injection-moulding operation. Alternatively, however, the threads 210, 310 can also be positioned only after the injection-moulding operation. Another advantage of the use of plastics material is that a plug connector housing 200 and a nut 300 of plastics material have resilient properties which facilitate the operation described of screwing the nut 300 onto the plug connector housing 200. However, the nut 300 and the plug connector housing 200 may also comprise a different material, for example, a metal.