Housing for an electrical device

Abstract

Housing (1) for an electrical device comprising an entry opening (12) for an electrical cable (15) with a hollow cylindrical nozzle (2) projecting outwards from the opening edge (11) of the insertion opening (12), the cavity of which is aligned with the insertion opening (12), the cylinder shell of which has an external thread (7) and the cylinder shell of which is perforated by at least two guide slots (3), with clamping wedges (11) guided longitudinally displaceably in the guide slots (3) with clamping surfaces (16) facing each other and wedge surfaces (14) facing away from each other, wherein the clamping wedges (4) can be inserted into the insertion opening (12) such that their wedge surfaces (14) are guided at the opening edge (11) of the insertion opening (12) and are screwed onto the external thread (7) by a drive nut (5) which, with its end wall (9) facing the housing (1), bears against the end surfaces (10) of the clamping wedges (4) facing it, such that when the drive nut (5) is screwed towards the housing (1), the clamping wedges (4) move towards each other with their clamping surfaces (16) for clamping fixation of an electrical conductor (15) inserted into the housing (1) through the insertion opening (12) between themselves, characterized by that at least a partial area of ​​the internal thread of the drive nut (5) is cut free in such a way that this partial area of ​​the internal thread is supported by a spring tongue (6) in the thread area of ​​the drive nut (5).

Description

[0001] The present invention relates to a housing for an electrical device. Such housings have an opening for an electrical cable. The electrical cable connects the electrical device to the outside world. For this purpose, the electrical cable is connected to the electrical device on the housing side via a connection element, for example, an electrical terminal, and has connection elements at its free end for electrical connection to the peripherals. The free end of the electrical cable is often equipped with a connector, a plug socket, or the like.

[0002] To prevent tensile stresses acting on the electrical conductor from impairing or destroying the electrical connection in the electrical device, strain relief is usually provided at the entry point in the housing. Common strain reliefs consist of a section of the conductor's outer sheath resting on a support surface, which is in turn bridged by a tab that can be screwed to the housing. The support surface and the tab act like clamps on the conductor's outer sheath, thus clamping the conductor securely between them.

[0003] These common strain reliefs are often time-consuming to install, especially when the interior of the housing is difficult to access. Frequently, the strain relief itself is technically quite complex.

[0004] Suitable enclosures for electrical devices with an insertion opening for a cable are known, for example, from US 6 149 455 A or DE 10 2014 200 133 A1.

[0005] Based on this, the invention aims to design a housing for an electrical device in such a way that the strain relief is structurally simple and can be easily installed.

[0006] This problem is solved in an inventive manner by the combination of features of claim 1. The dependent claims contain partly advantageous and partly inventive further developments of this invention.

[0007] The invention is based on the fundamental concept of creating strain relief with continuously moving clamping surfaces. In the final assembly state, the clamping elements clamp the electrical conductor between them. At least two clamping wedges are provided as clamping elements, their clamping surfaces facing each other and their wedge surfaces facing away from the clamping surfaces being guided along the edge of the insertion opening, for example, by being able to slide along the edge of the opening and bearing against it. Due to the wedge shape of the clamping wedges, their clamping surfaces move continuously closer together as the clamping wedges are pushed further into the insertion opening of the housing. As soon as the clamping wedges are firmly in contact with the outer sheath of the electrical conductor and thus clamp the conductor between them, the clamping wedges are also fixed in their final assembly position.

[0008] Extending from the entry opening is a tubular, outwardly projecting, hollow cylindrical stub. The cavity of the stub is flush with the entry opening. This allows the electrical cable to be inserted through the stub into the entry opening. The outer surface of the cylindrical stub has an external thread. A drive nut with an internal thread for the clamping wedges can be screwed onto this external thread.

[0009] To guide the clamping wedges, at least two guide slots are cut into the hollow cylindrical stub. These guide slots therefore penetrate the cylindrical surface of the stub. The clamping wedges are inserted into the guide slots in such a way that they are longitudinally displaceable along the central longitudinal axis of the electrical device housing. Within the guide slots, the clamping wedges can thus be moved towards the entry opening for the electrical cable on the device housing and ultimately inserted into the entry opening.

[0010] The drive nut, screwed onto the external thread, engages the end faces of the clamping wedges with its end face facing the housing. By screwing the drive nut onto the stub towards the housing, the clamping wedges are continuously advanced into the entry opening for the electrical conductor. This sliding movement ends as soon as the outer surfaces of the clamping wedges make firm contact with the outer sheath of the electrical conductor, thus clamping the conductor securely between them. To lock the clamping wedges in their clamped position, the drive nut is tightened further until it is self-locking against the clamping wedges, thus firmly securing them in this clamped position.To release the strain relief, the drive screw simply needs to be unscrewed away from the housing of the electrical device along the spigot, so that it releases the clamping wedges and the clamping wedges can also be moved away from the device housing in a longitudinal direction.

[0011] The tubular fitting thus has multiple functions: It serves as an entry point for the electrical cable. Furthermore, it acts as a threaded carrier for the external thread, providing a point of contact for the drive nut. Finally, it serves as a guide element for the clamping wedges.

[0012] To improve the clamping effect of the clamping wedges, an advantageous embodiment of the invention proposes providing guide grooves in the insertion opening of the device housing, adapted to the wedge surfaces of the clamping wedges. These guide grooves extend from the edge of the insertion opening into the insertion opening and thus into the device housing. The clamping wedges can thus bear against the guide grooves with their wedge surfaces, while the clamping force is introduced into the clamping wedges by means of the drive nut.

[0013] In connection with the invention, it is considered advantageous to arrange the guide slots at identical intervals within the cylinder. If two guide slots are provided, they are arranged opposite each other. If three slots are provided, they are arranged at an angle of 120° to each other. Four guide slots are advantageously arranged in a cross shape, i.e., at a distance of 90° to each other. While the number of clamping elements, i.e., clamping wedges, can be increased by providing more slots, the load-bearing capacity of the external thread is simultaneously reduced. Therefore, for the purpose of strain relief, two guide slots opposite each other, i.e., arranged at an angle of 180° to each other, are considered advantageous.

[0014] To improve the clamping fit of the clamping wedges on the outer sheath of the electrical conductor, a further embodiment of the invention proposes to provide the clamping surfaces with a profile, preferably with profile ribs.

[0015] To expedite the installation of the strain relief, the drive nut is designed as a locking screw nut. Such locking screw nuts feature tabs cut into the nut's surface, which engage a corresponding portion of the internal thread. These tabs are spring-mounted on the drive nut. This allows the drive nut to be ratcheted onto the external thread of the fitting until the end face of the drive nut rests against the end faces of the clamping wedges. The drive nut then only needs to complete a few turns to clamp the clamping wedges securely in their position relative to the electrical conductor.

[0016] The invention is described in further detail using an exemplary embodiment. The figures shown are: Fig. 1 an exploded view of the housing, the clamping wedges and the drive nut, Fig. 2 the parts described above in the assembled state in perspective view, Fig. 3 in the left part the side view of the case Fig. 2 and in the right part the same housing in a sectional view, Fig. 4 a top view of the housing Fig. 2 in the left part as well as in the right part the same housing in a corresponding sectional view, Fig. 5 a perspective view of the casing from Fig. 2 with an inserted electrical conductor with a large conductor diameter in the clamped state, Fig. 6 in the left part the side view of the case Fig. 5 and in the right part the same housing in a sectional view, Fig. 7 a top view of the casing Fig. 5 in the left part and in the right part the same housing in a sectional view, Fig. 8 a perspective view of the casing from Fig. 2 with an inserted electrical conductor with a small conductor diameter in the clamped state, Fig. 9 in the left part the side view of the case Fig. 8 and in the right part the same housing in a sectional view as well as Fig. 10 a top view of the casing Fig. 8 in the left part and in the right part the same housing in a sectional view.

[0017] Identical and structurally identical parts are identified by identical reference numbers. For clarity, not all figures include all reference symbols. Some figures contain simplified or schematic representations. Different views of the same parts may be scaled differently.

[0018] Fig. Figure 1 shows the housing 1 for the electrical device, the hollow cylindrical nozzle 2 with its two recessed guide slots 3, the two clamping wedges 4 that can be inserted into the guide slots 3, and finally the drive nut 5. The illustration of the drive nut 5 shows the cut-out, spring-loaded tongue 6, with which the drive nut 5 can be pushed onto the external thread 7 on the nozzle 2 in the central longitudinal direction 8.

[0019] In the presentation of the Fig. Figure 2 shows that the drive nut 5, with its end wall 9 facing the housing 1, can abut the end faces 10 of the clamping wedges 4 facing it. By further screwing in the drive nut 5 in the central longitudinal direction 8, the clamping wedges 4 can be screwed further into the housing.

[0020] From the sectional view of the Fig. 4. In the lower right, it can be seen that the clamping wedges 4 bear against the opening edge 11 of an insertion opening 12 of the housing 1. From the opening edge 11, 8 guide grooves 13 extend conically into the housing 1 in the central longitudinal direction. The taper of these guide grooves 13 is adapted to the taper of the clamping wedges 4, so that the wedge surfaces 14 are adapted to the shape of the guide grooves 13 and can slide into the housing 1 in the guide grooves 13 in the central longitudinal direction 8. In the illustration of the Fig. Figure 4 at the bottom right also shows an electrical conductor 15. The clamping wedges 4, with their clamping surfaces 13 facing away from the wedge surfaces 14, are clearly in contact with the outer sheath of the electrical conductor 15, thus clamping the electrical conductor 15 between them. All illustrations of the Fig. Figure 4 shows the drive nut 5 in the state of being merely pushed onto the external thread 7, in which the end wall 9 of the drive nut 5 does not yet touch the end surfaces 10 of the clamping wedges 4.

[0021] From a comparative analysis of Fig. 3 and Fig. 6 or Fig. 4 and Fig. Figure 7 shows that the clamping wedges 4 are significantly displaced into the insertion opening 12 of the housing 1 in the central longitudinal direction 8, because the end face of the drive nut 5 contacts the end faces 10 of the clamping wedges 4 there, and the drive nut 5 is screwed onto the external thread 7 in the central longitudinal direction 8 towards the housing 1. The drive nut 5 thus serves as a feed drive for the clamping wedges 4. The clamping wedges 4 are guided by the guide grooves 13 in the insertion opening 12 and screwed into the insertion opening 12 until the clamping surfaces 16, with their profile, effectively grip the outer sheath 7 of the electrical conductor 15, which in Fig. 7 and in Fig. 10 is shown in the bottom right corner.

[0022] From a comparative analysis of Fig. 6 and Fig. 9 on the one hand and Fig. 7 and Fig. 10 On the other hand, it is evident that with the invention electrical conductors 15 of different diameters can be connected to the electrical device in the housing 1. While Fig. 5 shows an electrical line 15 with a large diameter, shows Fig. 8 an electrical conductor 15 with a small diameter. It is noticeable that with an electrical conductor 15 with a large diameter, the transverse distance between the clamping surfaces 16 of the clamping wedges 4 is significantly larger in the clamped position than with an electrical conductor 15 with a small diameter. As a result of this larger transverse distance, the clamping wedges 4 are in Fig. 5, Fig. 6 and Fig. 7 also significantly further in the central longitudinal direction 8 out of the housing 1 than when the small diameter line 15 is clamped according to Fig. 8, Fig. 9 and Fig. 10. In Fig. In 5 ff., part of the external thread 7 is clearly visible in the clamped state of the clamping wedges 4 and the electrical conductor 15, whereas in the Fig. In the clamping shown in 8 ff., the drive nut 15 with its end wall 9 almost abuts the outer wall of the housing 1.

[0023] From a comparative analysis of Fig. 5, Fig. 6 and Fig. 7 on the one hand and the Fig. 8, Fig. 9 and Fig. 10 On the other hand, it is thus evident that, firstly, electrical cables of 15 different diameters can be securely fixed to the housing 1 with one type of housing or with one and the same strain relief. Secondly, the stepless adjustability or adjustability of the strain relief is evident.

[0024] Because the drive nut 5, with its free-cut tongue 6, can be pushed onto the external thread 7 until the end face 9 of the drive nut 5 abuts the end face 10 of the clamping wedges 4, the drive nut 5 can be quickly and securely locked onto the external thread 7. Only a short further turning of the drive nut 5 is required to achieve the clamping position of the clamping wedges 4. To remove the strain relief, the drive nut 5 only needs to be loosened by one or two turns to allow the drive nut 5, which is then no longer self-locking, to be pulled off the external thread 7. Reference symbol list 1 case 2 nozzles 3 guide slots 4 clamping wedges 5 drive nut 6 Tongue 7 external threads 8 Central longitudinal direction 9 Front wall 10 Front surface 11 Opening edge 12 Introduction opening 13 Guide groove 14 wedge surface 15 Management 16 clamping surface

Claims

[1] Housing (1) for an electrical device comprising an entry opening (12) for an electrical cable (15) with a hollow cylindrical nozzle (2) projecting outwards from the opening edge (11) of the insertion opening (12), the cavity of which is aligned with the insertion opening (12), the cylinder shell of which has an external thread (7) and the cylinder shell of which is perforated by at least two guide slots (3), with clamping wedges (11) guided longitudinally displaceably in the guide slots (3) with clamping surfaces (16) facing each other and wedge surfaces (14) facing away from each other, wherein the clamping wedges (4) can be inserted into the insertion opening (12) such that their wedge surfaces (14) are guided at the opening edge (11) of the insertion opening (12) and are screwed onto the external thread (7) by a drive nut (5) which, with its end wall (9) facing the housing (1), bears against the end surfaces (10) of the clamping wedges (4) facing it, such that when the drive nut (5) is screwed towards the housing (1), the clamping wedges (4) move towards each other with their clamping surfaces (16) for clamping fixation of an electrical conductor (15) inserted into the housing (1) through the insertion opening (12) between themselves, characterized by , that at least a partial area of ​​the internal thread of the drive nut (5) is cut free in such a way that this partial area of ​​the internal thread is supported by a spring tongue (6) in the thread area of ​​the drive nut (5). [2] Housing (1) according to claim 1 characterized by , guide grooves (13) in the insertion opening (12) extending from the opening edge (11) into the insertion opening (12) and adapted to the shape of the wedge surfaces (14) of the clamping wedges (4). [3] Housing (1) according to claim 1 or 2 characterized by , by means of identical distances between the guide slots (3) in the cylinder shell of the nozzle (2). [4] Housing (1) according to any one of claims 1 to 3 characterized by that the clamping surfaces (16) of the clamping wedges (4) have a profile, preferably profile ribs.

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