PARALLEL SCREW CONNECTION

Abstract

In parallel screw connections, which are preferably used in series terminals, the transmission of force from the connection screw to electric conductors which have different diameters is not always optimal. As a solution, the clamping element is mounted in or on the connection housing both in a movable manner as well as in a rotational manner about a rotational axis. By screwing the connection screw, the clamping element is moved in the direction of the electric conductor, mechanically contacts the electric conductor, is rotated by further screwing the connection screw about the rotational axis, and thus presses the electric conductor against the busbar with a corresponding degree of force. In this manner, an optimal pressing force is ensured independently of the respective diameter of the electric conductor.

Claims

1-15. (canceled)

16. A parallel screw connection comprising at least one connection housing, a connection screw and a clamping element, wherein the clamping element is mounted in or on the connection housing both in a displaceable manner and also in such a manner as to be able to rotate about an axis of rotation.

17. The parallel screw connection as claimed in claim 16, wherein the connection housing comprises a slot in each case on opposite-lying faces.

18. The parallel screw connection as claimed in claim 17, wherein the clamping element comprises a wheel axle that is held in the slot in a displaceable manner and a rotatable manner.

19. The parallel screw connection as claimed in claim 18, wherein the wheel axle is embodied in a cylindrical manner and comprises an axis of symmetry.

20. The parallel screw connection as claimed in claim 19, wherein the terminal body is mounted in a rotatable manner with its wheel axle in the slots, and wherein the axis of rotation of the clamping element corresponds to said axis of symmetry.

21. The parallel screw connection as claimed in claim 16, wherein the slots

22. The parallel screw connection as claimed in claim 16, wherein the clamping element is embodied in a symmetrical manner.

23. The parallel screw connection as claimed in claim 22, wherein the clamping element is embodied in an axis-symmetrical manner with respect to its axis of rotation.

24. The parallel screw connection as claimed in claim 22, wherein the clamping element has an n-fold rotational symmetry.

25. The parallel screw connection as claimed in claim 16, wherein the clamping element is a toothed wheel having multiple teeth.

26. The parallel screw connection as claimed in claim 25, wherein each tooth of the toothed wheel has a concave edge and a convex edge.

27. A terminal block comprising an insulation body and at least one parallel screw connection as claimed in claim 16, which is arranged therein, and at least one current rail that is arranged at least in part in the insulation body.

28. The terminal block as claimed in claim 27, wherein the current rail is arranged at least in part in the connection housing of the parallel screw connection.

29. The terminal block as claimed in claim 27, wherein the insulation body comprises at least one cable entry through which an electrical conductor can be inserted into the parallel screw connection, and the insulation body furthermore comprises at least one screw aperture through which the connection screw can be screwed into the connection housing so as to provide a contact between the electrical conductor and the current rail.

30. A method for providing an electrical contact between an electrical conductor wherein a connection screw is screwed into the connection housing in a parallel manner with respect to the current rail and the electrical conductor, and as a consequence presses a clamping element against the electrical conductor and presses this electrical conductor against the current rail, as a consequence of which the electrical conductor makes electrical contact with the current rail, wherein the clamping element is initially displaced in a direction towards the electrically conductor by virtue of screwing in the connection screw, subsequently makes mechanical contact with the electrical conductor and rotates about an axis of rotation by virtue of screwing the connection screw further in and as a consequence presses the electrical conductor against the current rail.

Description

EXEMPLARY EMBODIMENT

[0056] An exemplary embodiment of the invention is illustrated in the drawings and is further explained hereinunder.

[0057] In the drawings:

[0058] FIG. 1 illustrates a perspective view of a terminal block;

[0059] FIG. 2 illustrates a perspective view of a segment of a terminal block;

[0060] FIG. 3 illustrates an exploded view of a non-assembled screw connection with a connection housing and a separate toothed wheel, wheel axle, connection screw and current rail in an exploded view;

[0061] FIG. 4 illustrates a lateral view of the assembled screw connection with the inserted current rail;

[0062] FIG. 5a illustrates a cross-sectional view of the screw connection with the inserted current rail and a connection screw that is not screwed in and showing a cable that is to be inserted;

[0063] FIG. 5b illustrates a cross-sectional view of the screw connection in a state in which it makes contact with an inserted cable and a connection screw that has been screwed in;

[0064] FIG. 6 illustrates a view of the force vectors in the screw connection in the contacted state;

[0065] FIG. 7 illustrates the connection housing in the lateral view having a straight slot and an indicated axis of the slot.

[0066] The figures include in part simplified schematic views. Identical reference numerals are sometimes used for identical elements but where appropriate also for non-identical elements. Different views of identical elements can be scaled differently.

[0067] FIG. 1 illustrates a terminal block having an insulating body 1 that comprises multiple segments 11. Each segment 11 comprises in each case multiple cable entries 111 and each cable entry 111 is allocated a screw aperture 112.

[0068] FIG. 2 illustrates a cross-sectional view in particular of a single segment 11 of the insulating body 1 with four current rails 2 that are inserted therein in an exemplary manner and four parallel screw connections 3 that are likewise inserted in an exemplary manner having in each case a connection housing 31 and a connection screw 32, wherein one end of the respective current rail 2 is arranged in the respective connection housing 31 of the screw connection 3. In this manner, the respective current rail 2 is arranged at least in part in the segment 11 of the insulating body 1 and thus is also arranged in the insulating body 1. Furthermore, the respective current rail 2 is arranged at least in part in the respective connection housing 31 of the screw connection 3.

[0069] FIG. 3 illustrates an exploded view of a non-assembled screw connection 3 together with a current rail 2 that is inserted in the connection housing 31 that is associated with the screw connection 3. The connection housing 31 can be preferably embodied as a stamped and bent part.

[0070] In order to insert the current rail 2, the connection housing 31 comprises, in a first face that is covered by means of the connection housing 31 and is therefore not visible in the drawing, a first aperture that is accordingly likewise not visible in the drawing. In order to insert an electrical conductor, in particular a stripped region 41 of an electrical cable 4, the connection housing 31 comprises a second aperture 314 in a second face 317 that is arranged lying opposite the first face. Furthermore, a screw aperture 316 is arranged in this second face 317 and said screw aperture comprises an inner thread.

[0071] The current connection 3 comprises also a connection screw 32 that fits into the screw connection 316.

[0072] The connection housing 31 comprises a third face 318 and a fourth face 319 that are perpendicular to the first and the second face 317. These two faces 318, 319 comprise in each case a preferred straight slot 315, wherein the two slots lie symmetrically opposite one another. Only one slot 315 is visible in the drawing because the other one is covered by the connection housing 31.

[0073] Furthermore, the screw connection 3 comprises a clamping element, in particular a toothed wheel 33 that preferably comprises multiple teeth 331 that have in each case a concave edge and a convex edge. The toothed wheel 33 comprises in its middle a cylindrical through-going aperture 332. Furthermore, the toothed wheel 33 comprises a wheel axle 333 that is embodied in a cylindrical manner and can be inserted in a positive-locking manner into said through-going aperture 332.

[0074] FIG. 4 illustrates a lateral view of the assembled screw connection 3 with the inserted current rail 2.

[0075] The wheel axle 333 is inserted in a positive-locking manner into the cylindrical through-going aperture 332 of the toothed wheel 33 and the toothed wheel 33 is held in a displaceable and rotatable manner by means of this wheel axle 333 in the slots 315 of the connection housing 31. The toothed wheel 33 is arranged in this manner in the connection housing 3, The connection screw 32 is screwed in in part into the screw aperture 316.

[0076] Furthermore, an electrical cable 4 is illustrated as an electrical conductor with a stripped region 41. The current rail 2 has already been inserted through the first aperture into the connection housing 31. The electrical cable 4 is thus provided with its stripped region 41 to be inserted through the second aperture into the connection housing. A portion of the toothed wheel 33 is visible through the slot 315. Furthermore, the figure illustrates how the toothed wheel 33 is held in a rotatable and displaceable manner by means of the wheel axle 331 in the slot 315.

[0077] FIG. 5a illustrates a cross-sectional view of the same arrangement. The connection screw 32 is screwed in as far as a depth that is necessary so as to make a first mechanical contact with the toothed wheel 33.

[0078] As the connection screw 32 is screwed in, the toothed wheel 33 displaces initially in the direction towards the contacting stripped region 41 of the electrical cable 4. It is irrelevant whether the toothed wheel 33 also automatically performs an additional rotational movement; it is important that the toothed wheel 33 during this procedure in any case also comprises a movement component that corresponds to a translational movement, in other words the axis of rotation of the toothed wheel 33 in the form of its wheel axle 331 moves along the slot 315 in the direction towards the electrical conductor, namely in this case in the direction towards the stripped region 41 of the electrical cable 4, and as a consequence naturally also in the direction towards the current rail 2.

[0079] As soon as, as illustrated in FIG. 5b, the mechanical contact is provided between the toothed wheel 331 and the electrical conductor, in this case the stripped region 41 of the electrical cable 4, the connection screw 32 exerts a corresponding force on the toothed wheel 33. This screw force acts in particular on a tooth of the toothed wheel 33 and in particular on the convex edge of a tooth of the toothed wheel 33. The toothed wheel 33 exerts by way of a rotational movement a corresponding force on the electrical conductor, in particular on the electrical cable 4 on its stripped region 41, and consequently presses it against the current rail 2.

[0080] As a consequence, the electrical contact is provided between the electrical conductor, which is in particular the electrical cable 4, and the current rail 2.

[0081] FIG. 5b illustrates for this purpose, in a view that is comparable to FIG. 5a, the electrical cable 4 that is inserted with its stripped region 41 into the connection housing 31. The connection screw 32 is finally screwed in so as to make the contact.

[0082] It is obvious that the current rail 2 on the one hand and the electrical conductor, in particular the electrical cable with its stripped region 41, on the. other hand are inserted from opposite directions into the connection housing. The electrical cable 4 and the current rail extend within the connection housing in a parallel manner and furthermore in a parallel manner with respect to the axis of the connection screw.

[0083] FIG. 6 illustrates the equilibrium of forces in the screw connection for the above mentioned state in which the connection screw 32 is screwed in and the electrical contact is finally provided between the electrical conductor, in particular the stripped region 41 of the electrical cable 4, and the current rail 2. The electrical cable 4 and the current rail 2 are not illustrated in this view for reasons of clarity.

[0084] If it is assumed that the screw force is vertical (Y direction) and the clamping force is horizontal (X direction), then the following vector consideration is produced for the above described equilibrium of forces:

[0085] The following equilibrium of forces is produced in the vertical (Y) direction:

[0086] A force vector Fy2 that is absorbed by the bearing acts together with a frictional force vector Fy3 against the screw force vector Fy1, wherein the frictional force vector Fy3 describes the frictional force between the clamping element and the electrical conductor:

Fy1=Fy2+Fy3

[0087] The following equilibrium of forces is produced in the horizontal (X) direction:

[0088] A force vector Fx2 that is absorbed by the bearing acts together with a frictional force vector Fx1 against the clamping force vector Fx3, wherein the frictional force vector Fx1 describes the frictional force between the connection screw and the clamping element:

Fx+Fx2=Fx3

[0089] The clamping force and the frictional force of the clamping element at the cable are related to one another by way of the material-specific coefficient of friction :

Fy3=Fx3

[0090] The screw force and the frictional force of the clamping element at the connection screw are related to one another likewise by way of the material-specific coefficient of friction :

Fx1=Fy1

[0091] For the forces at the bearing point is applicable in dependence upon the angle of inclination , the by way of example the axis A of the straight slot forms with the X-axis; in the case of a curve-shaped slot, the angle is formed by the tangent of this curved shape in the bearing point and the X-axis:

Fx2=Fy2(sin30+cos30)/(cos30+sin30)

[0092] The following is thus produced in dependence upon the angle and the respective material of the terminal body:

Fx3=Fy1(.sup.2sin+2cos+sin)/(.sup.2cos+2sin+cos)

[0093] By way of example, the clamping element can be manufactured from steel. For the use of such a clamping element that is manufactured from steel, by way of example a material-specific coefficient of friction u of approx. 0.2 is produced. The design is however naturally not limited to the use of steel. On the contrary, it is also possible for example to use brass, copper, aluminum, synthetic material, ceramics or any other suitable material.

[0094] An angle of by way of example 30 can be assumed as the angle .

[0095] The following is then produced as the theoretically calculated value for the transmission of force:

Fx3/Fy1=78.7%

[0096] Since the slot 315 extends in a straight line, this value applies irrespective of the position of the bearing point, in other words irrespective of the position of the wheel axle 331 at the slot 315.

[0097] FIG. 7 illustrates a lateral view of the connection housing 31. The straight slot 315 is clearly visible. In particular, the axis A of said straight slot is clearly visible and includes an angle of 30 with the X-axis of the said coordinate system.

LIST OF REFERENCE NUMERALS

[0098] 1 Insulation body [0099] 11 Segment of the insulation body [0100] 111 Cable feed [0101] 112 Screw aperture [0102] 2 Current rail [0103] 3 Screw connection [0104] 31 Connection housing [0105] 314 Second aperture [0106] 315 Slot [0107] 316 Screw aperture [0108] 317 Second face [0109] 318 Third face [0110] 319 Fourth face [0111] 32 Connection screw [0112] 33 Toothed wheel [0113] 331 Tooth of the toothed wheel [0114] 332 Cylindrical through-going aperture [0115] 333 Wheel axle [0116] 4 Electrical cable, electrical conductor [0117] 41 Electrical conductor, stripped region of the electrical cable [0118] A Axis of the straight slot