Contact press-on assembly

Abstract

A contact press-on assembly for a switching contact piece of an electrical switching unit has a first stop and a second stop. A spring element extends between the two stops, wherein the first stop can move relative to the second stop. The second stop provides a counterbearing for the first stop, wherein a rotary bearing for the spring element can move together with the first stop.

Claims

1. A contact press-on assembly for a switching contact piece of an electrical switching unit, the contact press-on assembly comprising: stops including a first stop and a second stop, said first stop being movable relative to said second stop; and a spring element extending between said first stop and said second stop, said second stop forming an abutment for said first stop and at least one of said stops providing a rotary bearing for said spring element, said rotary bearing being movable together with said first stop, said rotary bearing protecting said spring element from transverse forces introduced from outside; wherein said abutment has a damping element for said first stop.

2. The contact press-on assembly according to claim 1, wherein said first stop is guided by said second stop.

3. The contact press-on assembly according to claim 1, wherein said stops are movable axially in relation to one another.

4. The contact press-on assembly according to claim 1, wherein said first stop has a rotationally movable disk, which is supported on said second stop.

5. The contact press-on assembly according to claim 4, wherein: said first stop has a carrying element; and said rotationally movable disk is connected to said carrying element of said first stop by way of a clearance fit.

6. The contact press-on assembly according to claim 1, wherein said first stop has a guide pin, which is at least partially enclosed by said spring element.

7. The contact press-on assembly according to claim 6, wherein said guide pin is guided by said second stop.

8. The contact press-on assembly according to claim 1, wherein said first stop and said second stop are guided in a telescoping manner.

9. The contact press-on assembly according to claim 1, wherein said spring element has a pressure stage.

10. An electrical switching device, comprising: switching contact pieces including a first switching contact piece and a second switching contact piece, which are movable relatively in relation to one another; a kinematic chain serving for a relative movement of said switching contact pieces in relation to one another, said kinematic chain having a contact press-on assembly, said contact press-on assembly containing: stops including a first stop and a second stop, said first stop being movable relative to said second stop; and a spring element extending between said first stop and said second stop, said second stop forming an abutment for said first stop and at least one of said stops providing a rotary bearing for said spring element, said rotary bearing being movable together with said first stop, said rotary bearing protecting said spring element from transverse forces introduced from outside; wherein said abutment has a damping element for said first stop.

11. The electrical switching device according to claim 10, further comprising a vacuum interrupter, said switching contact pieces defining a switching gap therebetween and disposed in said vacuum interrupter.

Description

(1) Hereinafter, an exemplary embodiment of the invention is schematically shown in a drawing and subsequently described in more detail.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(2) FIG. 1 shows a section through an electrical switching unit in the switched-off state;

(3) FIG. 2 shows a section through the electrical switching unit in the switched-on state;

(4) FIG. 3 shows a section through a contact press-on assembly as known from FIGS. 1 and 2 as a detail.

DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows an electrical switching unit, which has a vacuum interrupter 1. The vacuum interrupter 1 has an electrically insulating main body. The electrically insulating main body is in the present case of a hollow-cylindrical design and is aligned rotationally symmetrically with respect to a main axis 2. At the end faces, the main body of the vacuum interrupter 1 is closed off in a fluid-tight manner by electrically conducting closure caps, so that a vacuum is hermetically enclosed in the interior of the vacuum interrupter 1. The electrical switching unit also has a first switching contact piece 3 and a second switching contact piece 4. The two switching contact pieces 3, 4 are of the same construction. They respectively have a contact stem and also a contacting region. The switching contact pieces 3, 4 are arranged with their end faces opposite one another and aligned substantially coaxially with respect to the main axis 2, the contacting regions of the switching contact pieces 3, 4 facing one another. The first switching contact piece 3 is aligned fixed in place relative to the vacuum interrupter 1. The second switching contact piece 4 is aligned relatively movably with respect to the first switching contact piece 3. Arranged between the mutually facing ends (contacting regions) of the switching contact pieces 3, 4 is a switching gap 5. The contact stem of the first switching contact piece 3 is inserted at a fixed angle in the associated end-face closure cap of the vacuum interrupter 1. The second switching contact piece 4, or its stem, passes through the other electrically conducting closure cap of the vacuum interrupter 1. In this case, a reversibly deformable vacuum-tight bond between an end-face closure cap and the second switching contact piece 4 is formed by means of a bellows 6. Correspondingly, the second switching contact piece 4 is movable along the main axis 2, it being possible for a movement to be performed relative to the vacuum interrupter 1 and also relative to the first switching contact piece 3. The first switching contact piece 3 is connected at a fixed angle to a phase conductor 7, so that the vacuum interrupter 1 is mechanically supported on the phase conductor 7 by way of the first switching contact piece 3. Furthermore, an electrically conducting connection between the first switching contact piece 3 and the phase conductor 7 is provided by way of the contacting with the phase conductor 7. The second switching contact piece 4 is connected in an electrically conducting manner to a further phase conductor 8 by way of a suitable connection. By way of example, a flexible electrically conducting connection between the second switching contact piece 4 and the further phase conductor 8 is represented in the figure. It may also be provided that further suitable contacting means, such as for example sliding contacts, rubbing contacts or the like, are used in order to perform an electrical connection of the movable second switching contact piece 4 to the further phase conductor 8, and at the same time not appreciably impair the mobility of the second switching contact piece 4. Advantageously, electrical contacting of the second switching contact piece 4 and similarly of the second switching contact piece 3 takes place outside the vacuum interrupter 1. By way of the two switching contact pieces 3, 4, an electrically conducting connection between the phase conductor 7 and the further phase conductor 8 can be established or broken.

(6) In order to be able to bring about a movement of the second switching contact piece 4, a drive device 9 is provided. The drive device 9 can deliver a drive movement, in order to bring about a movement of the second switching contact piece 4. In order to transmit the movement in a suitable form, possibly transform or influence it, a kinematic chain 10 is used. The kinematic chain 10 extends from the drive device 9 to the second switching contact piece 4. For this purpose, the kinematic chain 10 has various transmission elements. On the one hand, a fixedly mounted two-arm deflecting lever 11 is provided, connected to the drive device 10 by a first lever arm by way of a connecting rod 12. The deflecting lever 11 is connected by a second lever arm to a push rod 13. The push rod 13 has an electrically insulating portion, so that an electrical insulation of the deflecting lever 11 and also of the further elements of the kinematic chain 10 that lie in the direction of the drive device 9 with respect to the second switching contact piece 4 is ensured. The push rod 13 has for example a tube which is formed from electrically insulating material, for example glass-fiber reinforced plastic.

(7) The push rod 13 is connected by its end remote from the deflecting lever 11 to a contact press-on assembly 14. The contact press-on assembly 14 serves for the transmission of a linear movement, which can be introduced to the contact press-on assembly 14 from the push rod 13. The contact press-on assembly 14 in turn is connected to the second switching contact piece 4, so that a movement introduced from the push rod 13 can be transmitted to the second switching contact piece 4 by way of the contact press-on assembly 14. The contact press-on assembly 14 has a first stop 15 and also a second stop 16. The first stop 15 is connected to the push rod 13. Arranged between the first stop 15 and the second stop 16 is a spring element 17. The spring element 17 serves for the transmission of a movement that originates from the first stop 15. The first stop 15 is guided by the second stop 16. The first stop 15 is guided in the manner of a piston within a cylinder-like opening of the second stop 16. The spring element 17 is in this case guided under pretension between the two stops 15, 16, the second stop 16 providing an abutment 18 for the first stop 15. A pretensioning of the spring element 17 between the two stops 15, 16 is made possible by the abutment 18. The first stop 15 is movable relative to the second stop 16, such a movement taking place by tensioning or relaxing the spring element 17. A more detailed construction of the contact press-on assembly 14 is shown by way of example in FIG. 3.

(8) In the case of a switching-on operation, a drive force is delivered by the drive device 9 to the kinematic chain 10. The connecting rod 12 activates the deflecting lever 11, whereupon the latter passes on a movement to the push rod 13. A rotationally movable coupling compensates for instances of overtravel caused by the rotational movements of the deflecting lever at the connecting rod 12 or push rod 13. In the case of a switching-on movement, a movement is applied by way of the first stop 15 to the (pretensioned) spring element 17, whereby the latter moves the first stop 16. Connected at a fixed angle to the first stop 16 is the second switching contact piece 4, so that a movement is also transmitted to the second switching contact piece 4. The second switching contact piece 4 approaches with its contacting region the contacting region of the first switching contact piece 3. The switching gap 5 is reduced in its extent along the main axis 2. A movement of the second switching contact piece 4 and similarly of the contact press-on assembly 14 in this case takes place substantially in the direction of the main axis 2. With contacting of the contacting regions of the first switching contact piece 3 and the second switching contact piece 4, a current path between the phase conductor 7 and the further phase conductor 8 is closed. In order to secure the position of the switching contact pieces 3, 4, after the contacting and after an end of the relative movement of the switching contact pieces 3, 4 in relation to one another, an overtravel is brought about by the drive device 9. On account of the fixed stopping of the second switching contact piece 4 against the first switching contact piece 3, the second stop 16 is prevented from further movement. Further driving of the drive device 9 has the effect of driving the first stop 15 further forward. On account of the fixing of the second stop 16, there is a tensioning of the spring element 17. After sufficient tensioning of the spring element 17, the drive device 9 is switched off, whereby the position of the push rod 13 is fixed. The push rod 13 consequently continues to press the first stop 15 against the second stop 16, with the tensioned spring element 17 interposed, and consequently the two switching contact pieces 3, 4 are pressed against one another. In the switched-on state, the contact press-on assembly 14 undertakes the securing of the relative position of the two switching contact pieces 3, 4 in relation to one another.

(9) The switched-on state of the electrical switching unit is shown in FIG. 2. In comparison with FIG. 1, it can be seen that the first stop 15 has moved away from the abutment 18, while the spring element 17 has undergone a tensioning.

(10) In the case of a switching-off operation (reversal of the movement from FIG. 2 to FIG. 1), the directional sense of the drive movement of the drive device 9 changes, i.e. the push rod 13 is moved with the opposite directional sense along the main axis 2 by way of the connecting rod 12 and the deflecting lever 11. As a result, first the spring element 17 is relaxed, until the first stop 15 comes to lie against the abutment 18 of the second stop 16. The spring element 17 is then under pretension. With the stopping of the first stop 15 against the abutment 18 of the second stop 16, a movement that is initiated by the push rod 13 is also transmitted by way of the contact press-on assembly 14 directly to the second switching contact piece 4. The second switching contact piece 4 moves relative to the first switching contact piece 3, so that an increase in the size of the switching gap 5 takes place.

(11) A construction of the contact press-on assembly 14 such as that known from FIGS. 1 and 2 is described on the basis of FIG. 3. The contact press-on assembly 14 has the second stop 16. The second stop 16 is designed in the manner of a cylinder, in which the first stop 16 is guided axially displaceably. A relative movement of the first stop 15 and the second stop 16 in this case takes place substantially along the main axis 2. An abutment 18 for the first stop 15 is formed in the present case in the manner that an annular disk constricts a cylindrical opening of the second stop 16 with a cup spring 19 (damping element) interposed. The elastic design of the abutment 18 has the effect that stopping of the first stop 15 against the abutment 18 is damped. Alternatively, instead of using a cup spring 19, some other dissipating element may also be provided.

(12) In order to be able to couple the first stop 15 to the push rod 13, the first stop 15 is provided with a carrying element 20. On the one hand, the carrying element 20 protrudes into the interior of the second stop, on the other hand, the carrying element 20 protrudes through the cylindrical opening of the second stop 16 out of the second stop 16. By means of a thread or a lug, the push rod 13 can be coupled indirectly or directly to the carrying element 20 by way of a rotary joint. The carrying element 20 is in this case formed substantially as a bolt, the bolt axis extending substantially coaxially with respect to the main axis 2. The carrying element 20 is provided with a collar 21, which extends radially around a lateral surface of the bolt of the carrying element 20. In this case, the position of the collar 21 is chosen in such a way that it is enclosed by the second stop 16. This collar 21 may suitably serve for stopping against the abutment 18, so that, driven by the spring element 17, loosening of the first stop 15 from the second stop 16 is prevented.

(13) The carrying element 20 has on the end face a rotationally movable disk 22. The rotationally movable disk 22 serves for allowing the spring element 17 to lie against the first stop 15. The rotationally movable disk 22 is mounted on the carrying element 20 rotatably relative to the main axis 2. In the present case, the rotationally movable disk 22 is formed in such a way that it covers the end face of the collar 21 that is facing the spring element 17 and also provides coverage of the collar 21 on the lateral surface. Together with the area with which the collar 21 comes to lie against the abutment, an in-line termination of the disk 22 is provided, so that both the collar 21 and the rotationally movable disk 22 come to lie against the abutment 18. On the lateral surface, the rotationally movable disk 22 is supported on the inner wall of a hollow-cylindrical clearance of the second stop 16 and guided in an axially movable manner. In order to perform improved guidance, on the lateral surface a sliding ring 23 is arranged on the circumference of the rotationally movable disk. The rotationally movable disk 22 serves for bearing the spring element 17, which presses the rotationally movable disk 22 against the abutment 18 as a result of a precompression with respect to the second stop 16. A clearance fit is formed between the rotationally movable disk 22 and the carrying element 20, whereby a low-cost rotationally movable guidance of the rotationally movable disk 22 on the carrying element 20 is obtained.

(14) In order to ensure improved radial and axial guidance of the rotationally movable disk 22 on the carrying element 20 of the first stop 15, the rotationally movable disk 22 is centrally provided with a guide pin 24. The guide pin 24 extends centrally within the cylindrical clearance of the second stop 16. In this case, part of the carrying element 20 also extends within the guide pin 24, whereby the guide pin 24 is formed at least in portions both by the rotationally movable disk 22 and by the carrying element 20. Between the outer lateral surface of the guide pin 24 and the inner lateral surface of the cylindrical clearance of the second stop 16, the spring element 17 lies in an annular gap. The spring element 17 is in the present case designed in the form of a helical spring, it being a so-called helical spring with a pressure stage, i.e. a tensioning of the spring element 17 takes place with the turns coming closer together.

(15) At its end remote from the abutment 18 of the first stop 15, the guide pin 24 is provided with an end-face clearance, into which the second stop 16 protrudes with a portion. As a result, the first stop 15 and the second stop 16 are connected to one another in a telescoping manner, one of the stops 15, 16 entering the other when there is a relative movement of the first stop 15 with respect to the second stop 16. To improve the sliding connection between the first stop 15 and the second stop 16, a further sliding bush 25 is incorporated on the inner lateral surface in the clearance of the guide pin 24. Arranged on the second stop 16 coaxially with respect to the alignment of the carrying element 20 of the first stop 15 is a threaded rod 26, by means of which the contact press-on assembly 14 is connected at a fixed angle to the second switching contact piece 4 by way of the second stop 16.

(16) In the case of a switching-on operation before contacting of the two switching contact pieces 3, 4, the precompression of the spring element 17 is chosen in such a way that the spring element 17 presses the first stop 15 against the abutment 18, the second stop 16 forming the basis for the relative movement of the first stop 15 on account of the mounting of the abutment 17. Until there is contacting of the two switching contact pieces 3, 4, the spring element 17 ensures a rigid coupling of the two stops 15, 16. Also in this state, rotational movements in the first stop 15 can be neutralized. With galvanic contacting of the two switching contact pieces 3, 4 and continuing movement within the kinetic chain 10, there is a deformation of the spring element 17 (tensioning of the spring element 17) as a result of a relative movement of the first stop 15 with respect to the second stop 16. The tensioned spring element 17 can then bring about a contact-pressing force between the two switching contact pieces 3, 4. In the case of a switching-off operation, a reversal of the directional sense of the movement of the kinematic chain 10 takes place. At first there is a relaxation of the spring element 17 and a removal of the stops 15, 16 from one another, until the first stop 15 butts against the abutment 18. This butting is damped by the cup spring 19. With the first stop 15 lying against the abutment 18, a movement that is initiated by the drive device 9 is then transmitted by way of the kinematic chain, and is also transmitted to the second switching contact piece 4. The second switching contact piece 4 detaches itself from the first switching contact piece 3 and moves away.

(17) On account of the diverse transmission elements in the path of the kinematic chain and the deflection or transformation of the movement, transverse forces that put a load on the individual bearing points or deflecting points may occur in the kinematic chain 10. The use of a first stop 15 with a rotary bearing allows rotational movements that could continue to the second switching contact piece 4 to be neutralized in the contact press-on assembly. The rotary joint in the first stop serves as a freewheeling mechanism, so that rotational movements are decoupled from the switching contact pieces 3, 4. In addition, the spring element 17 is protected from rotational loads that could change the spring behavior of the spring element 17. When there is a movement of the first stop 15, the rotary bearing that is arranged between the carrying element 20 and the rotationally movable disk 22 on the first stop 15 is moved together with the latter. As a result, loading or securing of the rotary bearing by the spring element 17 is ensured independently of a relative position of the stops 15, 16 in relation to one another and the state of the kinematic chain. Correspondingly, a neutralization of undesired forces in the kinematic chain can be performed by means of a single movable rotary bearing. In this way, on the one hand undesired movement at the switching contact pieces 3, 4 is prevented, on the other hand the contact press-on assembly 14 is kept free of such forces, it being possible for a neutralization of the forces to be brought about in the contact press-on assembly 14 itself can be effected.