EP1032083A2 - Cable clamp for the mechanical holding and the electrical connection of a cable - Google Patents

Abstract

The cable clamp (10) has a 2-part housing (20.50) enclosing a clamping device (16) cooperating with the inserted electrical cable (12), which is engaged by at least 2 pairs of opposing deformation elements (22,52; 24,54) with different clamping directions, positioned one after the other along the cable longitudinal axis.

Description

The invention relates to a cable clamp for mechanical holding and electrical Connect a cable, with a two-piece housing and one Clamping device for a cable to be inserted into the housing.

Such a cable clamp can be installed in a control cabinet, for example his. There are various requirements for such a cable clamp. To the one must enable reliable electrical connection of the cable. At the same time, strain relief must be provided, by means of which the cable is inserted in such a way the cable clamp is held that tensile loads applied to the cable are not are transmitted to the electrical connection, but previously derived into the housing become. Finally, such a cable clamp can be used to create a electrical shielding in the area of the connection of the cable with the electrical Provide connection.

Two concepts are known from the prior art by means of which attempts are made will, both a secure mechanical hold of the cable in the cable clamp as well to ensure good electrical shielding. One concept provides one Form cable receptacle, on which several screws are provided, which in Attack the screwed-in condition on the jacket of the cable. If the cable is connected to a Shielding is provided, this can be 180 ° on the jacket of the cable bent back and contacted there. Another concept is one Press the retaining ring onto the sheath of the cable. This ring is then in one appropriate receptacle of the housing inserted and acts as a strain relief. If before the pressing of the retaining ring exposed a shield of the cable and on the Jacket is bent back, the retaining ring can contact this shield and together with an electrically conductive receptacle serve to provide good shielding to ensure the cable clamp.

A disadvantage of these concepts is the very high effort involved in inserting them and attaching the cable.

The object of the invention is a cable clamp of the type mentioned Art in such a way that a cable to be inserted into the cable clamp minimal effort mechanically reliable can be set, while at the same time there should be the possibility of a large shielding of the cable to be inserted Effort to contact electrically.

This object is achieved by a cable clamp at the beginning mentioned type, which is characterized in that at least two pairs of mutually opposite deformation elements are provided, which at attack closed housing and inserted cable and deform it, wherein the deformation elements of the first pair face each other in a clamping direction opposite, which deviates from the clamping direction in which the Deformation elements of the second pair are opposite, and wherein the two pairs, viewed along the longitudinal axis of the cable to be inserted into the cable clamp, are arranged one behind the other. Under the term "clamping direction" Direction understood along which the two deformation elements of a pair one Apply clamping force to the inserted cable, this direction generally also applies the direction of the shortest connection between the two deformation elements together.

In general terms, a cable clamp according to the invention is based on the Basic idea that the holding force to be provided for the purpose of strain relief of at least two pairs of deformation elements arranged one behind the other provided. These deformation elements are designed so that those of them caused deformation of the cable differs in the direction. If for example, the first and the second deformation element pair the cable with im Deform the initial state of the round cross-section into an oval cross-section from the longer main axis of the oval cross section in the area of the first Deformation element pair predetermined direction from the direction from that longer main axis of the second oval cross-section is determined. The evoked Deformation does not necessarily have to be oval or elliptical Cross section of the cable. Depending on the design of the deformation elements as well The deformation behavior of the cable can also be constricted, for example Cross section result. In any case, this results in the clamping direction in which the Deformation elements are opposite, a reduction in the diameter of the Cross-section, while there is an enlargement approximately perpendicular to this clamping direction of the diameter of the cross section. Because of the different orientation the deformed cross-sections of the cable pulls the cable out of the Cable clamp in addition to the frictional forces at the points of attack Deformation elements are generated on the cable, still a deformation resistance opposite. If the cable were to be pulled out, every position of the Cable which is deformed in a first direction on a pair of deformation elements, deformed in another direction in the subsequent pair of deformation elements become. This multiple deformation of the cross section acts from the Material stiffness of the cable against the resulting resistance to deformation.

According to a preferred embodiment of the invention it is provided that the from the first pair of deformation elements determined clamping direction by about 90 ° is rotated relative to the clamping direction by the second Deformation element pair is determined. With this design there is a maximum Resistance if tensile forces act on the cable.

According to the preferred embodiment of the invention, there is also a third Deformation element pair provided, the second deformation element pair between the third pair of deformation elements and the first Deformation elements pair is arranged and that of the third Deformation element pair determined clamping direction approximately with that of the first Deformation elements pair certain clamping direction matches. At this Design creates three deformed cross sections of the cable, each of which is differ from the adjacent cross section. In this way the Strain relief effect improved.

It is preferably provided that a deformation element of a pair on the first part of the housing and the associated other deformation element on the second part of the housing is attached. This design results in a minimal Assembly effort. The cable only needs to be inserted into one of the housing parts. The strain relief results automatically when the second housing part attached and connected to the first housing part.

According to the preferred embodiment of the invention, it is further provided that a deformation element consists of a rib that is perpendicular in one plane extends to the longitudinal axis of the cable to be received in the cable clamp. The Using a rib as a deformation element offers several advantages. To the one can be easily manufactured, especially if the two housing parts as Injection molded parts are formed. Furthermore, by designing the Geometry of the rib, for example the edge engaging the cable and the width this edge, the deformation of the cable and the resulting resistance and Set holding forces freely.

For example, it is possible that the rib on the cable has a straight edge attacks with respect to a tangent to the outer circumference of the cable to be inserted is slightly inclined. With this design, the insertion of the cable is facilitated; In addition, the risk of damage to the cable during insertion is reduced.

The two edges preferably lie in a clamping direction opposite, which is approximately perpendicular to the direction in which the housing is closed. With this design, the necessary to clamp the cable Pushing forces applied when closing the housing. Because of the wedge effect no particularly high forces are required to close the housing already a few screws to reliably close the housing. Also are no special precautions against deformation of the housing

Alternatively it is provided that the rib on the cable with a projection attacks. This design leads to a precisely defined contact zone between the rib and cables, so that a high even with comparatively low pressure forces Surface pressure and thus high friction can be achieved.

Preferably, the protrusion has a vertex that is on the cable attacks. By selecting the radius of curvature of this vertex, Art and how the cable is deformed by the protrusion. If for example, the radius of curvature at the apex is smaller than the radius of the The outer circumference of the cable to be inserted results from sufficient deformability of the cable a deformed cross section, which corresponds approximately to an ellipse, which in the area its short semiaxes is severely constricted, namely in the area in which the Crest apex attacks. If, on the other hand, the cable is only a small one Has deformability, the vertices acting on the cable lead to the fact that there is an oval cross section.

It is preferably provided that the two projections in one another Clamping direction opposite, which corresponds approximately to the direction in which the Housing is closed. With this design, the clamping effect of the Ribs achieved automatically when closing the housing without additional steps required are.

According to the preferred embodiment, at least one is U-shaped Holding section provided, the distance between the two legs of the Holding section is smaller than the outer diameter of the cable to be inserted. This Holding section is used to fix the cable in one housing part before the other Housing part is attached.

The holding section is preferably opposite the deformation elements offset laterally so that the cable to be inserted is deflected by a central axis. The lateral deflection of the cable increases the strain relief resistance provided.

According to a preferred embodiment of the invention it is provided that the Deformation elements pairs are electrically conductive and on a shield of the attack the inserted cable in an electrically conductive manner. Thus, without an additional Work step an electrical shielding of the cable with a ground connection get connected. Preferably, the housing is also electrically conductive, so that the im Housing trained electrical connection of the cable is also shielded. The electrical contact between the shield of the cable and the electrically conductive Deformation element pairs can be achieved in two ways: Firstly the pairs of deformation elements can be designed as cutting edges, the one Penetrate the sheathing of the cable and attack the shielding of the cable, so that it is electrically conductively contacted. On the other hand, the shielding of the Cable is exposed before insertion in the cable clamp and 180 ° on the jacket of the Fold the cable back so that it lies on the outer circumference of the cable. The Deformation element pairs then automatically attack the shield, whereby at the same time the mechanical hold of the cable is achieved in the cable clamp.

Advantageous refinements of the invention result from the subclaims.

• Figur 1 eine perspektivische Ansicht einer erfindungsgemäßen Kabelklemme und eines in diese einzulegenden Kabels;
• die Figuren 2a bis 2g Querschnitte der erfindungsgemäßen Kabelklemme in unterschiedlichen Ebenen;
• die Figuren 3a bis 3g die Querschnitte von Figur 2 mit eingelegtem Kabel;
• Figur 4 in vergrößertem Maßstab den Querschnitt von Figur 2e; und
• Figur 5 in vergrößertem Maßstab den Querschnitt von Figur 2f.

The invention is described below with reference to a preferred embodiment which is illustrated in the accompanying drawings. In these show:

• Figure 1 is a perspective view of a cable clamp according to the invention and a cable to be inserted therein;
• Figures 2a to 2g cross sections of the cable clamp according to the invention in different levels;
• Figures 3a to 3g the cross sections of Figure 2 with inserted cable;
• Figure 4 shows the cross section of Figure 2e on an enlarged scale; and
• 5 shows the cross section of FIG. 2f on an enlarged scale.

A cable clamp 10 can be seen in FIG. It serves an electrical cable 12 mechanically record and connect electrically.

The cable clamp 10 has a first housing part 20 and a second housing part 50 The second housing part 50 can be attached to the first housing part 20 in the manner of a cover attached and fastened to it with three screws 14. The two Housing parts can consist of plastic and be made in one piece, be hinged to each other, for example, by a plastic film hinge.

The housing 10 is generally designated 16 Strain relief provided, which consists of a first pair of deformation elements 22, 52, a second pair of deformation elements 24, 54 and a third pair of Deformation elements 26, 56 there. The strain relief 16 is as follows described in more detail with reference to Figures 2 to 5.

In Figure 2a is a schematic section through the strain relief 16 along the plane X-Y (see Figure 1) shown. In Figures 2b to 2g cross sections are perpendicular to Axis X is shown in the area of the strain relief 16, the respective plane in FIG 2a is designated. For example, the representation of the in Figure 2a with the Letter c designated cross section in Figure 2c.

The strain relief 16 has one on the outside of the cable clamp 10 Input cross section that is larger than the cross section of the cable 12 to be received is. As can be seen in FIG. 36, the cable 12 runs freely through the input cross section through it.

At the entrance cross section in the plane c is a U-shaped Stop section. This is provided by two on the first housing part 20 Legs 28, 30 formed. The legs 28, 30 lie at such a distance from one another opposite that there was a slight deformation of the originally circular Cross section of the cable 12 comes to an oval cross section. This is too in Figure 3c see; the original cross-section is indicated by a solid line, and the deformed cross section is indicated by the double hatching. The two legs 28, 30 are opposite a central axis M which is aligned with the X axis of the cable coincides, offset laterally so that the cable 12 is deflected to the side.

Two close to the holding section arranged in the plane c in the plane d Deformation elements 22, 52. The deformation elements are designed as ribs, wherein the rib 22 is provided on the first housing part 20, while the rib 52 on second housing part 52 is provided. The ribs have two straight edges 23, 53 on, which are intended to attack the cable 12 (see Figure 3d) The two Edges 23, 53 face each other in a clamping direction, in the direction corresponds in which a clamping effect is exerted on the cable 12 Edges 23, 53 with respect to the direction in which the two housing parts 20, 50 are joined together and which is symbolized by the arrow P in FIG. 2d, slightly arranged at an angle, so that when the two are put together Housing parts 20, 50 results in an increasing wedge effect. This wedge action causes that despite the comparatively small forces involved in joining the two Housing parts 20, 50 are required, a comparatively high clamping effect on the Cable 12 can be exercised in the plane d. Thus, the cable 12 is based on its originally circular cross section in those shown in Figure 3d, strong deformed elliptical cross section; the clamping direction is therefore approximately horizontal.

The edges 23, 53 run to the free ends of the ribs 22, 52 in insertion bevels from the automatic positioning and centering of the cable in the Pair of clamping elements 22, 52 guaranteed. Furthermore, in the area of the free ends Ribs 22, 52 recordings in the corresponding opposite housing part provided so that the spreading forces occurring during the deformation of the cable safely are reliably received and do not lead to any deformation of the housing can.

A section with the one in FIG. 2b is connected to the deformation elements 22, 52 shown cross section, in which the cable returns to its undeformed has circular cross section.

Subsequently, a second pair of deformation elements 24, 54 arranged. Deviating from the first pair of deformation elements are here rib-shaped projections used with their apices 25, 55 on the attack cable 12 to be picked up. The radius of curvature r at the apex of the Deformation elements 24, 54 (see also Figure 4) is smaller than the radius of the Outer periphery of the cable 12. This means that with the usual cables that are in the Cable clamp 10 are added, the originally circular cross-section in the cross-section shown in Figure 3e is deformed, which is generally an ellipse with a severe constriction in the area of the short semiaxes. In dependence of the respective properties of the cable to be accommodated, in particular deformability of the jacket of the cable and outside diameter, but can also be different deformed cross sections result, for example, an elliptical cross section without Constriction.

The first deformation element 24 is formed on the first housing part 20, and that second deformation element 54 is formed on the second housing part 50. Furthermore, on second housing part 50 a receptacle for the deformation cross section e laterally delimiting rib extending from the first housing part 20 intended. In this way, the clamping force between the apexes 25, 55 automatically caused when the two housing parts 20, 50 are joined, whereby the receptacle for the rib extending from the first housing part 20 for a precise positioning of the two housing parts relative to each other ensures.

The second pair of deformation elements is followed by a section like it is shown in Figure 2b. In this section, the cable to be picked up has one circular cross section.

Then there is a third pair of deformation elements in plane f, the ribs 26, 56 provided here being the ribs 22 known from plane d, 52 correspond. However, the ribs are arranged in reverse here: The with respect Figure 2 on the left side of the cable attacking rib 26 is now in one piece with the first housing part 20 is formed, while on the right side of the cable engaging rib 56 is formed on the second housing part 50. That way the total force acting on the second housing part along the axis Y = 0, since the compressive force applied to rib 52 is approximately equal to that applied to rib 56 Pressure force is. In Figure 5 it can be seen that the free end of the rib 26 on the second Housing part 50 is received and that the free end of the rib 56 in a receptacle is recorded on the first housing part 20.

A holding section is then arranged in the plane g, as it basically consists of level c is known. The two legs 32, 34 determine a cross section that is offset in the opposite direction with respect to the central axis M as in the plane c.

A cross section is arranged towards the inside of the housing, as it is from level b is known. The cable therefore has a circular cross section.

This sequence of pairs of deformation elements results in the negative X direction of the cable considers a sequence of different cable cross sections: When entering the cable clamp 10, the cable has a round cross section. The cable is then deformed into an oval cross section, the longer one Semi-axes are aligned in the Z direction, since the clamping direction is roughly along the Y axis is aligned. Then the cable is tied into one elliptical cross-section deformed, with the longer semiaxes of the ellipse in the Y direction are aligned since the clamping direction is aligned along the Z axis is. Then the cable is reshaped into an elliptical cross-section, whose longer semi-axes are aligned in the Z direction. Finally the cable inside the cable clamp again a circular cross-section. In addition, the cable in the area of the holding sections, which are located in levels c and g, from the central axis M deflected. Because of this design results in comparatively low pressure forces when joining the two Housing parts 20, 50 must be applied, a very large holding force. Because only very low pressure forces have to be applied are only comparatively few Screws or similar elements are required to secure the two housing parts connect with each other. In addition, the housing does not have to be stiffened or expensive be carried out particularly solid, since only small clamping forces from the screws applied and routed to the appropriate locations on the housing. In Depending on the respective dimensions and the cable taken Holding forces up to over 100 N can be achieved. Due to the relatively low pressure forces, which must be exerted on the cable in order to achieve the desired holding forces, Signs of settlement of the cable, especially the sheath, play a great deal less role in the case of cable clamps from the prior art, with a lot larger pressure forces have to work.

If a shielded cable clamp together with a shielded cable is used, the deformation elements in the plane e together with those from level d and / or level f can be used to shield the To contact the cable electrically. Because this way, the shielding in total at least four points are contacted, which are at an angular distance of 90 ° to each other are arranged with a slight offset in the X direction, which corresponds to Contacting the shielding qualitatively approximates such contacting received, for example, by a clamp surrounding the shield by 360 ° becomes.

Claims (16)

Cable clamp (10) for mechanically holding and electrically connecting a cable (12), with a two-part housing (20, 50) and a clamping device (16) for a cable (12) to be inserted into the housing (20, 50).
characterized in that at least two pairs of mutually opposing deformation elements (22, 52; 24, 54) are provided which act on the housing when the housing (20, 50) is closed and the cable inserted and deform it, the deformation elements (22, 52) of the first pair are opposite to each other in a clamping direction that deviates from the clamping direction in which the deformation elements (24, 54) of the second pair are opposite, and the two pairs are viewed along the longitudinal axis (M) of the cable to be inserted into the cable clamp, are arranged one behind the other. Cable clamp according to claim 1, characterized in that the of the first deformation element pair (22, 52) determined clamping direction by about 90 ° is rotated relative to the clamping direction by the second Deformation elements pair (24, 54) is determined. Cable clamp according to claim 1 or claim 2, characterized in that a third pair of deformation elements (26, 56) is provided, which is arranged so that the second pair of deformation elements (24, 54) between the third Pair of preforming elements (26, 56) and the first pair of deformation elements (22, 52) is arranged, which determined by the third pair of deformation elements (26, 56) Clamping direction approximately with that of the first pair of deformation elements (22, 52) certain clamping direction matches. Cable clamp according to one of the preceding claims, characterized characterized in that a deformation element (22, 24, 26) of a pair on the first Part (20) of the housing and the associated other deformation element (52, 54, 56) the second part (50) of the housing is attached. Cable clamp according to one of the preceding claims, characterized characterized in that a deformation element (22, 24, 26; 52, 54, 56) from a rib exists, which is in a plane perpendicular to the longitudinal axis (M) of the in the cable clamp extends cable (12). Cable clamp according to claim 5, characterized in that the rib (22, 26; 52, 56) on the cable with a straight edge (23, 27; 53, 57), which with respect slightly tangent to the outer circumference of the cable (12) to be inserted is. Cable clamp according to claim 6, characterized in that the straight edge (23, 27; 53, 57) is provided with an insertion bevel at one end. Cable clamp according to claim 6 or 7, characterized in that the two Edges (23, 27; 53, 57) face each other in a clamping direction, which is approximately is perpendicular to the direction (P) in which the housing (20, 50) is closed. Cable clamp according to claim 5, characterized in that the rib (24, 54) engages the cable (12) with a projection. Cable clamp according to claim 9, characterized in that the projection has an apex (25, 55) which engages the cable (12). Cable clamp according to claim 10, characterized in that the Radius of curvature (r) at the apex (25, 55) is smaller than the radius of the Outer circumference of the cable (12) to be inserted. Cable clamp according to one of claims 9 to 11, characterized in that the two projections face each other in a clamping direction, which is about corresponds to the direction (P) in which the housing (20, 50) is closed. Cable clamp according to one of the preceding claims, characterized characterized in that at least one U-shaped holding section is provided, wherein the distance between the two legs (28, 30; 32, 34) of the holding section is smaller is the outside diameter of the cable (12) to be inserted. Cable clamp according to claim 13, characterized in that the Holding section is laterally offset from the pairs of deformation elements, so that the cable (12) to be inserted is deflected by a central axis (M). Cable clamp according to one of the preceding claims, characterized characterized in that the deformation element pairs are electrically conductive and at one Attack the shielding of the inserted cable (12) in an electrically conductive manner. Cable clamp according to claim 15, characterized in that the two Housing parts (20, 50) are electrically conductive.

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