Coupling for Power Cables

Abstract

The invention relates to a coupling for power cables, consisting of a plug part (1) and a socket part, said plug part (1) having a basic body (2) comprising a coupling pin (3) on which a locking pin (4) is arranged, said locking pin (4) being mounted in the plug part (1) so as to be displaceable in the axial direction of the coupling pin (3), said locking pin (4) being held in a basic position towards a back end (11) of the coupling pin (3) by a spring force and, while the coupling is being locked, being moved by interlocking with a helical groove of the socket part towards the front end (12) of the coupling pin (3) and a spring device (16) being loaded in the process.

Claims

1. A coupling for power cables having a plug part (1) and a socket part (7), said plug part (1) and said socket part (7) comprising a device for connecting a power cable (6) in a fixed manner, said plug part (1) comprising a basic body (2) which has a coupling pin (3) projecting over a front side (27) of the basic body (2) and is arranged in the axial direction of the coupling and has a locking pin (4) laterally arranged on the coupling pin (3), said socket part (7) comprising a basic body (8) which is provided with an axial bore (9) for accommodating the coupling pin (3), said axial bore (9) comprising, in a bore wall (29), a groove (10) which starts from a front side (28) of the basic body (8) and comprises a helical segment (24) and extends to the front end of the basic body (8), said groove (10) serving to accommodate a locking pin (4) of the plug part (1) such that when an engagement connection is produced between the plug part (1) and the socket part (7), the coupling pin (3) is inserted into the bore (9) of the socket part (7) in such a manner that the locking pin (4) is accommodated in the groove (10) of the socket part (7) and the plug part (1) and the socket part (7) are clamped against each other like a bayonet connector by means of the locking pin (4) guided in the groove (10) via a subsequent relative rotation of the plug part (1) and the socket part (7), characterized in that the locking pin (4) is displaceably mounted in the plug part (1) in the axial direction of the coupling pin (3), said locking pin (4) being held in a basic position towards a back end (11) of the coupling pin (3) by means of a spring device (16) and said locking pin (4) being displaced towards the free end (12) of the coupling pin (3) by interlocking with the groove (10) in the socket part (7) when the engagement connection is produced between the plug part (1) and the socket part (7) and the spring device (16) thus being loaded so as to form a pre-load force.

2. The coupling for power cables according to claim 1, characterized in that the coupling pin (3) of the plug part (1) is provided with a central through bore (13) as well as a radial recess (14), a tension rod (15) being guided in the central through bore (13), said tension rod (15) being provided with the locking pin (4) radially arranged on the front end, said locking pin (4) passing through the radial recess (14) and the spring device (16) being arranged between the basic body (2) and the tension rod (15) in such a manner that when the engagement connection is produced between the plug part (1) and the socket part (7), the locking pin (4) is displaced into the socket part (7) and the pre-load force increases.

3. The coupling for power cables according to claim 1, characterized in that the spring device (16) comprises at least one plate spring (17).

4. The coupling for power cables according to claim 1, characterized in that a stop for limiting the movement of the locking pin is formed at the front end of the coupling pin.

5. The coupling for power cables according to claim 4, characterized in that the stop for the movement of the locking pin (4) is defined by the end of the spring path of the at least one plate spring (17).

6. The coupling for power cables according to claim 1, characterized in that the coupling pin is mounted axially displaceable in the basic body of the socket part, said coupling pin being provided with a radially arranged locking pin and the spring device being arranged between the basic body and the coupling pin in such a manner that when the engagement connection is produced between the plug part and the socket part, the coupling pin is pulled out of the basic body and the pre-load force increases.

7. The coupling for power cables according to claim 1, characterized in that the groove (10) formed in the socket part (7) comprises a groove segment (25) arranged parallel to the front side (28) at the end of the groove (10) facing away from the front side (28) in such a manner that when the engagement connection is produced between the plug part (1) and the socket part (7), a continuous increase of the pre-load of the spring device (16) remains constant at first while the locking pin (4) is being displaced in the area of the helical segment (24) of the groove (10) and subsequently the pre-load force remains constant while the locking pin (4) is being displaced in the area of the groove segment (25).

8. The coupling for power cables according to claim 1, characterized in that the groove (10) formed in the socket part (7) comprises a groove segment (26) facing back to the front side (28) at the end of the groove (10) facing away from the front side (28) in such a manner that when the engagement connection is produced between the plug part (1) and the socket part (7), a continuous increase of the pre-load force of the spring device (16) is continuously reduced at first while the locking pin (4) is being displaced in the area of the helical segment (24) of the groove (19) and subsequently the pre-load force is continuously reduced while the locking pin (4) is being displaced in the area of the groove segment (26).

9. The coupling for power cables according to claim 1, characterized in that either the plug part (1) or the socket par (7) is intended to be installed in an electrical device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the following, advantageous embodiments of the invention are further described by way of the drawing.

[0027] In the drawing,

[0028] FIG. 1 shows a plug part of a coupling in an isometric view;

[0029] FIG. 2 shows a longitudinal cut through the plug part shown in FIG. 1;

[0030] FIG. 3 shows a top view of the plug part shown in FIG. 1;

[0031] FIG. 4 shows a socket part of a coupling in an isometric view;

[0032] FIG. 5 shows a side view of the socket part shown in FIG. 4;

[0033] FIG. 6 shows a partial cross-sectional view of a basic body of the socket part shown in FIG. 4 according to the cutting line VI-VI in FIG. 4;

[0034] FIG. 7 shows a cross-sectional view of the basic body shown in FIG. 6 according to the cutting line VII-VII in FIG. 6 along with a view of a first embodiment of a groove formed in the basic body;

[0035] FIG. 8 shows a second embodiment of the groove shown in FIG. 7.

DETAILED DESCRIPTION

[0036] In a synopsis of FIGS. 1 to 3, a plug part 1 of the coupling is shown which comprises a coupling pin 3 which starts from a front side 27 of a basic body 2 and has a longitudinal bore 13. In conjunction with the longitudinal bore 13, the coupling pin 3 comprises a recess 14 preferably produced by milling for accommodating a locking pin 4. The locking pin 4 is formed by an elbowed end of a tension rod 15 accommodated in the longitudinal bore 13, said locking pin 4 formed by the elbowed end passing through the recess 14 and radially protruding over the coupling pin 3. This elbowed and protruding end of the tension rod 15 forms the locking pin 4 which can be displaced in the longitudinal direction of the plug part 1, the other end of the tension rod 15 being locked against the basic body 2 of the plug part 1 by means of a spring device 16 which comprises a plate spring 17 in the present instance. For this purpose, the plate spring 17 is arranged between a bore offset of the longitudinal bore 13 formed in a basic body 2 and a nut 19 arranged on a thread offset 20 of the tension rod 15 in the illustrated exemplary embodiment.

[0037] Using one or more plate springs as a spring element of the spring device 16 proves to be particularly advantageous since plate springs are able to develop large spring forces in small ranges and installation spaces. It is also particularly advantageous if the maximum spring path of the locking pin 4 can be limited without any other components by pressing the spring plate flat and the plate spring then forming a mechanically stiff stop. By tightening the coupling accordingly, the same high contact forces can be attained between the two coupling halves as in rigid couplings according to the state of the art which comprise an immovable locking pin.

[0038] In FIGS. 4 to 8, a socket part 7 is shown which comprises an accommodating bore 9 formed in a basic body 8 for accommodating the coupling pin 3 of the plug part 1. In a bore wall 29 of the basic body 8, a groove 10 is formed which comprises different groove segments, namely a groove beginning segment 23, a helical segment 24 and a groove segment 25 and 26. By combining groove segments with different inclinations, the coupling can be better secured against becoming unintendedly loosened. The groove beginning segment 23 extends to the accommodating bore 9 arranged parallel to the axis starting from a front side 28 of the basic body 8. The groove beginning segment 23 serves to easily insert the coupling pin 3 of the plug part 1 into the socket part 7. The helical segment 24 follows immediately thereafter, said helical segment 24 comprising a constant positive inclination.

[0039] In order to produce a coupling connection between the plug part 1 and the socket part 7, the locking pin 4 is inserted into the groove beginning segment 23. When subsequently rotating the plug part 1 against the socket part 7, the locking pin 4 of the plug part 1 follows the helical segment 24 of the groove 10, whereby the coupling parts are pulled together like in a bayonet connector, a surface contact is formed between the front sides 27, 28 and the spring device 16 is loaded.

[0040] In the embodiment of the groove 10 shown in FIG. 7, a groove segment 25 connects with zero inclination, i.e. the groove segment 25 extends parallel to the front side 28 of the basic body. Once the locking pin 4 reaches the groove segment 25, the spring device 16 is not loaded any further. However, a force component is no longer produced which is directed towards the opening rotating direction of the coupling, something that is still the case with a positive inclination in the helical segment 24. Only the friction forces between the coupling parts, i.e. the plug part 1 and the socket part 7, act against this force component so that the coupling can be opened more easily, i.e. with less expenditure of force, than it can be closed. It is achieved via the arrangement of the groove segment 25 that internal forces in the coupling are no longer exerted when opening the connection and that the required external force for opening the connection is increased since the supporting force is dispensed via the inclined plane between the locking pin 4 and the helical segment 24.

[0041] When guiding the locking pin 4 into the helical segment 24 of the groove 10, i.e. when locking the bayonet connector, subsequent to the plug part 1 shown in FIG. 2 being inserted into the socket part 7 shown in FIG. 5, the tension rod 15 is pulled out of the plug part 1 against the pre-load force of the spring device 16, whereby the contact force is precisely defined. When loosening the plug part 1, the contact force between the front sides 27, 28 forming the contact surfaces continuously drops according to the characteristic curve of the spring, a sudden release and thus an immediate loosening of the connection as in the state of the art being reliably prevented. Thermal expansion and setting behaviors of the connection are elastically compensated without it having to come to a relevant change in the pre-load force. Thus, the ohmic contact resistance of the connection practically remains constant.

[0042] This new situation, which represents a significant technological advancement, only becomes possible via the socket part according to the invention. Additionally, the socket part according to the invention can be realized in such a manner that it remains compatible with already existing plug parts realized in a rigid manner having an immovable locking pin according to the state of the art. This is attained by realizing the helical segment so that a rigidly installed locking pin, which is geometrically realized according to the standard IEC 60974-12, cannot reach the subsequent groove segment.

[0043] In the embodiment of the groove 10 shown in FIG. 8, the groove segment 26 comprises a negative inclination so that the groove segment 26 is faced back towards the front side 28. In this instance, the user of the coupling will notice a significant change in the tightening torque when the spring-loaded locking pin 4 is transferred from the helical segment 24 having a positive inclination into the groove segment 26 having a negative inclination. This tightening torque will suddenly decrease when the helical segment 24 transfers to the groove segment 26 which will intuitively be understood as the coupling locking. The user will therefore know that the coupling is correctly locked. For detaching the coupling, an increasing torque must first be mustered in order to overcome the transition point between the helical segment 24 and the groove segment 26 of the groove 10. An accidental loosening is therefore not possible.