EP0141423B1 - Device for relieving strain on wires - Google Patents

Abstract

1. A device (1) for holding and relieving force on wires and cables, especially for relieving strain on insulated connection cables of electrical devices, whereby at least a non-positive fastening is provided between the apparatus and the device (1), and whereby said device (1) comprises at least two holding sections (2, 3) being arranged in a wedge-shaped manner to each other and forming together in respect of said wire a feed-through opening (4) and has an essentially U-shaped fastening section (5) and whereby, when a force occurring in reverse direction to said wedge direction, is acting upon said wire, said holding sections (2, 3) being relatively arranged to each other, will be brought into said feed-through opening (4) narrowing and/or non-positive strain blocking engagement with said wire, wherein at least two of said holding sections (2, 3) being wedge-shaped to each other are arranged on both legs (8, 9) of said U-shaped fastening section (5) such that a clamping gap perpendicular to the cable axis is obtained as a feed-through opening (4).

Description

The invention relates to a device for holding and relieving the force of lines and cables according to the preamble of claim 1.

A device of the generic type is used above all for fixing electrical cables surrounded by an insulation jacket, that is to say, for example, for fixing conventional connecting cables which are round in cross section or ribbon cables. In particular, the device can be provided as a cable clamp for the connecting lines of electrical devices.

To fasten connecting cables in plugs, a clamp is usually used, which can be fastened to the plug housing with one or two screws. After the connection cable to be fixed has been carried out between the connector housing and the clamping bracket, the clamping bracket is brought so far against the connection cable and its insulation jacket through the screw connection that a firm seat is created in both directions. This results in strain relief for the connecting cable in both directions.

A disadvantage of this conventional type of device and cable clamp is that the assembly process with screwing on the clamping bracket, inserting the connecting cable and re-screwing is very time-consuming and therefore costly. On the other hand, it is often found after stripping the electrical lines to be connected that the length of the electrical conductor remaining between the cable clamp and the connecting pole or connecting pin is too long or too short. In these cases in particular, the cable clamp must be loosened and fastened again.

Since the cable clamp as a conventional part is mostly an integrated part of the connector housing, the entire plug must be replaced if the cable clamp is damaged. In the case of a separate clamping bracket, this is usually fixed to the connector with two screws, so that both screw connections for fastening and strain relief of the connecting cable must be actuated.

Another type of generic cable clamp is known from German Offenlegungsschriften DE-A-26 55 127, DE-A-29 23 812. The cable clamp consists of an essential ring-shaped frame that surrounds the cable and elastic-flexible gripping fingers, which are arranged on the ring-shaped frame and, in their untensioned state, extend obliquely in the direction of the cable path and with free ends in the region of the cable path lie, with the fingers converging in one direction along the cable path with these. If the free cable end is loaded by a tensile force against the wedge direction of the gripper fingers, the diameter of the through opening, which is formed by the gripper fingers resting on the cable, is reduced, thereby increasing the form-fitting engagement of the gripper fingers on the insulating jacket of the cable, so that pulling through the Cable becomes impossible. With the opposite direction of loading, however, the lead-through opening increases and the cable can be pulled through.

A disadvantage of a cable clamp of this type is that, in the case of a ring-shaped construction, the cable must be inserted by pushing the cable through the ring-shaped frame and the gripping fingers, as a result of which the cable can only be readjusted in the wedge direction of the gripping fingers, and this with approximately U- Shaped design, as described in DE-A-26 55 127, the insertion and readjustment can only be done by removing the device from the device and bending the device.

Based on this prior art, the invention has for its object to improve a generic device so that the implementation or insertion of lines and connecting cables can be realized easily and without screw connection, with a reliable mounting of the line introduced into the device and its Strain relief against forces directed away from the connection object is guaranteed.

This object is achieved according to the invention in a generic device by the features of the characterizing part of claim 1.

The main idea of the invention is to provide the device or cable clamp with two wedge-shaped mutually opposing holding areas, which form a clamping gap for the cable to be carried out or inserted by the at least slight spreading of the holding areas resulting from the material tension holding force is exerted on at least one peripheral area of the line. Here, the material stiffness is chosen in accordance with the material thickness of the holding areas so that when a tensile force is exerted on the line in the direction of the wedge configuration of the holding areas, the line can be pulled against the holding force through the clamping gap formed between the holding areas. In the case of a tensile force contrary to the wedge configuration, on the other hand, the width of the clamping gap is reduced, so that the non-positive or positive engagement of the holding areas with the line is increased, making it impossible to pull the line through. In the latter case, the insulation jacket of the conductor is therefore pressed together more strongly by the holding areas, whereby the angular position of the holding areas with respect to one another changes to a larger, possibly obtuse angle.

With a view to simple assembly, it is particularly advantageous to make the device essentially U-shaped open. The plane of the U-shape is perpendicular to the longitudinal extension of the line. In this configuration, the U-shaped opening of the device is aligned with the clamping gap formed between the holding areas in such a way that the line or the cable can be inserted into the device approximately perpendicular to its longitudinal extent. The opening of the U-shape is usually kept larger than the width of the clamping gap. This is intended to keep the insertion force in the direction of the clamping gap extension as low as possible. To improve the guidance when inserting the cable into the clamping gap, the holding areas on the side of the U-shaped opening are chamfered, so that a continuous, more or less strong spreading of the holding areas on the clamping area takes place when the cable is inserted.

The ends of the holding areas are advantageously wedge-shaped, the one outer surface being largely perpendicular to the cable extension. In the case of an insulation jacket of the cable consisting of an elastomer, a punctiform or linear engagement with the insulation jacket is achieved in this way. This embodiment facilitates on the one hand a frictional pulling through of the cable in the direction of the wedge shape and on the other hand offers the guarantee that an immediate narrowing movement of the holding areas relative to one another with a type of self-locking clamping action against the cable is achieved with a tensile force contrary to the wedge shape.

Depending on the intended use, a clamping gap formed by holding areas can be produced on both sides of the fastening area, particularly in the case of a U-shaped design of the device. The holding areas or clamping gaps are preferably formed mirror-symmetrically to the central plane of the fastening area. This symmetrical design ensures strain relief in both directions. In addition, in the same way as in the case of a simple clamping gap, the fixed cable can be removed with a subsequent shift in length with a simple handle. Such removal can be necessary to adjust the length of the connection points of the electrical conductors. Such a length shift may also be necessary due to the wear of the insulation jacket resulting from the tensile load in a certain area.

In the case of a simple clamping gap, the device can also have a closed fastening area, in which case the cable end must be pushed through the opening and the clamping gap in the wedge direction.

In the structurally simplest form, two holding areas are provided, which are arranged at an angle of preferably 90 ° to one another. This wedge angle is dependent on the material rigidity, the geometric dimension of the arrangement area of the strain relief, the desired holding and clamping force, can be changed to an obtuse or more acute angle. From a cost-saving point of view, the full function of the device is fulfilled by two flat webs of approximately the same length, the edge of which is rectilinear at the clamping gap. In a change to this, this edge can also have a partial form fit, e.g. B. as a pitch circle for the cable to be jammed. In this case there is an exact position fixation in the clamping gap, which is otherwise guaranteed by the holding or clamping forces. Likewise, even with a U-shaped design of the device, more than two retaining webs can be provided, which, however, must leave the insertion plane of the cable free.

As a mass product, the device is preferably made of a plastic which has high dimensional stability and is in particular electrically insulating. The device is advantageously produced as a separate, one-piece part which has a complementary, form-fitting fastening area with a larger device unit. For small parts, such as plugs, the device can of course be integrated as part of the small device. For example, an ABS plastic or a polycarbonate PC can be selected as the material.

To improve the overall rigidity of the device, in particular in the case of a U-shaped design, a reinforcing rib is preferably provided on the connection area of the U-shape, in the direction of the holding areas. The reinforcing rib gives the device a particularly high material stability, so that the spreading forces occurring when a cable is inserted into the clamping gap can be better absorbed and cracking in the material is avoided. In an alternative form, the edge of the holding areas at the clamping gap can also have a curvature course, optionally ribbed, in the longitudinal direction of the cable. This course of curvature is then to be designed such that, in the case of tensile forces opposite to the wedge orientation of the holding areas, a narrowing of the clamping gap occurs with, if possible, larger surface contact on the insulation jacket of the cable. Although this self-locking narrowing of the device is preferred, there is also the possibility of a positive locking intervention of the Stopping areas with the cable, e.g. B. on a larger diameter cable stage. This can be viewed as an alternative, but preferably also in addition to the narrowing clamping gap.

The device has the particular advantage that, as a separate or integrated line or cable clamp designed in a larger housing unit, without screw fastening and simple installation of the cable to be inserted, strain relief is possible on one or both sides. Here, a length shift of the cable can be implemented easily and in the shortest possible time.

• Fig. 1 eine Draufsicht auf eine U-förmige Vorrichtung in Richtung der Keilform ihrer Haltebereiche;
• Fig. 2 einen Schnitt durch die Vorrichtung nach Fig. 1 längs der Linie 11-11;
• Fig. 3 eine Draufsicht auf die Vorrichtung nach Fig. 1 von oben;
• Fig. 4 eine Ansicht der Vorrichtung nach den vorausgehenden Figuren 1 bis 3 auf die Seite ihrer Haltebereiche entgegengesetzt zu deren Keilkonfiguration; und
• Fig. 5 einen Schnitt durch die Vorrichtung nach Fig. 4 längs der Linie V-V.

The invention is explained below with reference to schematic drawings of an embodiment of the device. Show it:

• Figure 1 is a plan view of a U-shaped device in the direction of the wedge shape of its holding areas.
• FIG. 2 shows a section through the device according to FIG. 1 along the line 11-11;
• 3 shows a top view of the device according to FIG. 1 from above;
• 4 shows a view of the device according to the preceding FIGS. 1 to 3 on the side of its holding areas opposite to its wedge configuration; and
• Fig. 5 shows a section through the device of FIG. 4 along the line VV.

In the embodiment shown in the figures, the device is made in one piece from a relatively rigid plastic and can be used as a cable clamp 1 with strain relief. The cable clamp 1 essentially has a U-shaped fastening area 5, between the two legs 8 and 9 of which an opening 10 is formed. In Figure 1, the cable clamp 1 is shown in plan view of the surface facing away from its holding areas 2 and 3. The periphery of the cable clamp 1 is at least essentially a complementary form to the arrangement area in the associated larger device unit. The outer regions running vertically in FIG. 1 are preferably designed as stepped guide surfaces 11. In combination with the rounded base area of the fastening area 5, the cable clamp 1 can be positively inserted in a holder of the larger device unit, e.g. B. a connector. The cable clamp 1 is preferably inserted into the larger device unit in the direction of the base region 16 of the U-shape.

As is shown more clearly in FIG. 5, the opening 10 of the cable clamp 1 is kept substantially larger than the through-opening for a corresponding line or a cable which is designed as a clamping gap 4 at the ends of the holding areas 2 and 3. Formed directly onto the legs 8 and 9 of the U-shaped cable clamp 1, the holding areas 2 and 3 extend in a wedge shape against one another, the angle enclosed between the holding areas preferably being 90 °. The inner transition between the holding areas 2 and 3 and the corresponding legs 8 and 9 is shaped as a rounding 23, so that the expansion forces upon enlargement of the clamping gap 4 or forces resulting from a strain relief when narrowing the clamping gap 4 better from the shape Fastening area can be transferred.

In the exemplary embodiment, the holding areas 2 and 3 provided for power transmission and strain relief of the cable are provided symmetrically to the vertical axis of the cable clamp 1, which follows the section line 11-11 in FIG. 1. According to the sectional view according to FIG. 2 and the top view according to FIG. 4, the holding areas 2 and 3 are formed on the fastening area 5 only in the area of the U-legs 8 and 9, respectively. In relation to the entire longitudinal extent of the cable clamp 1, the holding areas engage approximately in the middle area of the U-legs and are kept somewhat shorter than the total length of the legs 8 and 9 when fully functional. In the top view according to FIG. 4, the holding areas can be 2 and 3 are accordingly characterized approximately as plate-shaped spreading surfaces which form the clamping gap 4 between their inner edge which runs approximately parallel to the vertical axis.

As can be seen particularly clearly in FIGS. 2 and 3, a stiffening web 15 is formed on the base region 16, projecting approximately perpendicularly from it in the direction of the extent of the holding regions 2 and 3, and is essentially triangular in plan view according to FIG. 3 . This stiffening web 15 serves to better absorb the spreading forces acting on the U-shaped fastening area 5. However, the stiffening web 15 also simultaneously takes on the function of a stop or contact surface of the cable inserted into the clamping bead 4 and not shown in the example.

The wedge-shaped and tongue-like holding areas 2 and 3 preferably have a slightly smaller material thickness than the U-shaped fastening area 5. The outer surface 19 of the holding areas 2 and 3 facing away from the fastening area 5 in the area of the clamping gap 4 is bevelled approximately parallel to the base area 16 . As a result, the edge of the holding areas 2 and 3 is designed as a wedge tip, which brings about a good holding and clamping fit with the insulation jacket, particularly in the case of an insulation jacket of the cable consisting of an elastomer.

The length of the triangular stiffening web 15 is in the embodiment in the vertical direction, the U-shaped fastening area 5 is kept shorter than the extent of the holding areas 2 and 3 in this direction. As can be clearly seen in particular in the plan views according to FIGS. 1 and 2, the holding areas 2 and 3 have beveled surfaces 21 on the side facing the opening 10, which result in a funnel-shaped guidance in the direction of the clamping gap 4.

The attachment of a cable of the cable clamp 1 is preferably carried out in such a way that the cable, not shown, is first introduced into the U-shaped opening 10 with a longitudinal extension into the plane of the drawing when the cable clamp 1 is arranged according to FIG. 1. By further moving approximately along the vertical axis according to FIG. 1, the insulation jacket of the cable comes into engagement with the chamfered surfaces 21 of the holding areas 2 and 3. Through these chamfered surfaces 21, the cable is continuously pushed into the holding and clamping gap 4 in cross-section. Since the clamping gap 4 is smaller than the smallest outer diameter of the cable to be used, the tongue-like holding areas 2 and 3 are more or less spread apart at least in the area of the clamping gap. The frictional application of the holding areas to a part of the outer circumferential surface of the cable fixes the position with sufficient accuracy, but the cable can be pulled through the clamping gap 4 in this direction when a force acts in the wedge direction of the holding areas. The force required for this depends on the diameter relations of the cable or the clamping gap as well as on the choice of material, the material thickness and the angular position of the holding areas.

In contrast to this, a tensile force acting opposite to the wedge direction of the holding areas is absorbed by the self-locking narrowing of the clamping gap 4 between the holding areas. As a result, the outward and mostly externally acting tensile forces, which are directed downward according to FIG. 3, are received by the cable clamp 1 in a non-positive and / or positive manner and transmitted to the larger device unit.

In the event of a change in the cable length or an exchange of the cable, this is possible by applying force in the direction of the longitudinal extent of the clamping gap 4 or in the direction of the opening 10 from the cable clamp without the time-consuming and labor-intensive opening required in conventionally known devices.

Claims (7)

1. A device (1) for holding and relieving force on wires and cables, especially for relieving strain on insulated connection cables of electrical devices, whereby at least a non-positive fastening is provided between the apparatus and the device (1), and whereby said device (1) comprises at least two holding sections (2, 3) being arranged in a wedge-shaped manner to each other and forming together in respect of said wire a feed-through opening (4) and has an essentially U-shaped fastening section (5) and whereby, when a force occurring in reverse direction to said wedge direction, is acting upon said wire, said holding sections (2, 3) being relatively arranged to each other, will be brought into said feed-through opening (4) narrowing and/or non-positive strain blocking engagement with said wire, wherein at least two of said holding sections (2,3) being wedge-shaped to each other are arranged on both legs (8, 9) of said U-shaped fastening section (5) such that a clamping gap perpendicular to the cable axis is obtained as a feed-through opening (4).

2. The device according to claim 1 wherein said holding sections (2, 3) on the open side (10) of said U-shaped fastening section (5) comprise each a sloping entrance (21) verging into said clamping gap (4).

3. The device according to any of the claims 1 to 2 wherein said fastening sections (2, 3) at said clamping gap (4), in a section taken in longitudinal direction of said inserted wire, are formed in a wedge-shaped manner by an outer surface (19) approximadely perpendicular to said wire direction.

4. The device according to any of the claims 1 to 3 wherein at least said fastening sections (2, 3) consist of a dimensionally stable, especially electrically insulating, synthetic material.

5. The device according to any of the claims 1 to 4 wherein on both sides of said U-shaped open fastening section (5), viewed in the direction of said wire, each two of the conjugated fastening sections (2, 3), each of which constituting jointly a clamping gap (4) in one wire direction, are formed.

6. The device according to any of the claims 1 to 5 wherein a reinforcement link (15) is provided on said base (16) of said U-shaped fastening section (5) approximately perpendicular to said U-shaped leg connection.

7. The device according to any of the claims 1 to 6 wherein said device (1) is made of one piece or as an integral part of an apparatus.

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