Abstract
A contact for a vacuum interrupter of a low, medium or high-voltage switchgear includes a contact rod composed of a first electrically conductive material and extending along a longitudinal axis of the contact, and a contact piece composed of a second electrically conductive material and fastened to an end face of the contact rod. The contact rod and the contact piece are materially bonded to one another at a connecting face. At least one of the contact rod or the contact piece has a wall which delimits the connecting face, rises perpendicularly to the longitudinal axis and is disposed such that the contact piece and the contact rod are also force-lockingly connected to one another by a force acting transversely to the longitudinal axis between the contact piece and the contact rod. A production method for such a contact is also provided.
Claims
1-10. (canceled)
11. A contact for a vacuum interrupter of a low, medium or high-voltage switchgear, the contact comprising: a contact rod extending along a longitudinal axis of the contact and having a first electrically conductive material and an end face; a contact piece fastened to said end face of said contact rod, said contact piece having a second electrically conductive material and a contact surface remote from said contact rod; said contact piece and said contact rod being materially bonded to one another on a connecting face; and at least one of said contact rod or said contact piece having a wall configured to delimit said connecting face, rise perpendicularly relative to said longitudinal axis and force-lockingly interconnect said contact piece and said contact rod due to a force acting transversely to said longitudinal axis between said contact piece and said contact rod.
12. The contact according to claim 11, wherein said contact rod and said contact piece are soldered to one another.
13. The contact according to claim 11, wherein said wall runs concentrically around said longitudinal axis.
14. The contact according to claim 11, which further comprises a trench running at least approximately parallel to said wall, said trench disposed on a side of said wall remote from said contact face of said contact piece.
15. The contact according to claim 11, wherein said contact piece has a passage formed therein having a first opening and a second opening, said first opening being open toward said contact face of said contact piece and said second opening being open toward a side of said contact piece remote from said contact face of said contact piece.
16. The contact according to claim 15, wherein said contact rod has a formation disposed in said passage formed in said contact piece.
17. The contact according to claim 11, wherein a first coefficient of thermal expansion of the first material is greater than a second coefficient of thermal expansion of the second material.
18. The contact according to claim 11, wherein the first material is copper, stainless steel, or a copper or stainless steel alloy.
19. The contact according to claim 11, wherein the second material is a copper-chromium composite material, a tungsten-copper compound, or a tungsten carbide-metal compound.
20. The contact according to claim 11, wherein: the first material is copper, stainless steel, or a copper or stainless steel alloy; and the second material is a copper-chromium composite material, a tungsten-copper compound, or a tungsten carbide-metal compound.
21. A method for producing a contact, the method comprising steps of: producing the contact according to claim 11 by: providing said contact rod; providing said contact piece; force-lockingly interconnecting said contact rod and said contact piece by applying a pressing force along the longitudinal axis; and materially bonding said contact rod and said contact piece to each other by heating said contact rod and said contact piece.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The invention will be explained in more detail below with reference to drawings of exemplary embodiments, in which:
[0025] FIG. 1 shows a sectional illustration through an example of a vacuum interrupter in which a contact according to the invention can be used;
[0026] FIG. 2 shows a sectional illustration through a first exemplary embodiment of a contact according to the invention;
[0027] FIG. 3 shows a sectional illustration through a second exemplary embodiment of a contact according to the invention;
[0028] FIG. 4 shows a sectional illustration through a third exemplary embodiment of a contact according to the invention;
[0029] FIG. 5 shows a sectional illustration through a fourth exemplary embodiment of a contact according to the invention;
[0030] FIG. 6 shows a sectional illustration through a fifth exemplary embodiment of a contact according to the invention;
[0031] FIG. 7 shows a sectional illustration through a sixth exemplary embodiment of a contact according to the invention; and
[0032] FIG. 8 shows one exemplary embodiment of the method according to the invention for producing a contact according to the invention.
DETAILED DESCRIPTION OF THE DRAWING
[0033] FIG. 1 shows a sectional illustration through an example of a vacuum interrupter 100 in which a contact 1 according to the invention can be used. The vacuum interrupter 100 comprises two contacts 1, which are arranged opposite one another in a ceramic housing 7 and of which usually one is in the form of a movable contact and the other is in the form of a fixed contact. In this respect, the movable contact can be displaced along a movement direction 4 within the vacuum interrupter 100, with the result that respective contact faces 14 of the two contacts 1 can be brought into contact with one another or separated from one another. In this respect, a flexible bellows 5 ensures that the vacuum prevailing in the vacuum interrupter 100 is maintained in spite of the movement of the movable contact.
[0034] Each contact 1 comprises a contact rod 2, which extends along a longitudinal axis 13, and a contact piece 3, which is fastened to one end of the contact rod 2 and has the opposite contact faces 14. A shield 6 serves to protect the underlying ceramic from being sputtered by contact material from switching arcs and possibly to take on a potential lying between the potentials of the contacts 1, as a result of which the electrical field prevailing in the vacuum interrupter 100 can be advantageously influenced.
[0035] FIG. 2 shows a sectional illustration through a first exemplary embodiment of a contact 1 according to the invention. The contact rod 2 of the contact 1 has a formation 10, which is introduced in a correspondingly shaped passage 11 in the contact piece 3. The formation 10 may in particular be cylindrical. The passage 11 has the additional advantage that gas located between the contact rod 2 and the contact piece 3 can escape when the vacuum soldering furnace is being evacuated. If gas remains in the vacuum soldering furnace, undesired chemical reactions can occur on the surfaces of the contact 1 and inside the vacuum interrupter 100. Moreover, trapped gas can prevent the formation of a material bond of sufficient quality.
[0036] According to the invention, what is provided is a wall 8 which, in the exemplary embodiment shown here, is arranged on the contact rod 2 and, more specifically, on the formation 10 of the contact rod 2. The wall 8 encircles the formation 10 and can thus constitute a ring around it. The ring can in particular be arranged concentrically around the longitudinal axis 13 of the contact 1. The wall 8 serves to produce a force-locking connection between the contact rod 2 and the contact piece 3, before subsequently a material bond is produced. The force-locking connection holds the contact piece 3 and the contact rod 2 in the desired position relative to one another to establish
[0037] the materially bonded position. For the latter, solder 9, for example a solder film, can be placed between the contact rod 2 and the contact piece 3 at the location where the material bond is to be brought about on a connecting face of the two parts. The wall 8 serves in this respect as a boundary of the connecting face, since the solder 9 heated and liquefied during the production of the material bond cannot pass the wall 8. This prevents the liquefied solder 9 from leaving the region of the connecting face, which if it does happen can result in the quality of the material bond being adversely affected and the contact face 14 of the contact piece 3 being contaminated with solder.
[0038] FIG. 3 shows a sectional illustration through a second exemplary embodiment of a contact 1 according to the invention. In the second exemplary embodiment, that end of the contact rod that is connected to the contact piece 3 has a stepped form. In the second embodiment, the wall 8 delimits the connecting face on its other side. The first and the second exemplary embodiment can advantageously be combined in one vacuum interrupter 100, when the upper contact is implemented according to the first exemplary embodiment and the lower contact is implemented according to the second exemplary embodiment, since, in the event of the vacuum interrupter 100 being placed upright in the vacuum soldering furnace, the solder 9 can be kept at the intended location against the action of gravitational force for both contacts.
[0039] FIG. 4 shows a sectional illustration through a third exemplary embodiment of a contact 1 according to the invention, in which two walls 8 are provided, as a result of which the robustness of the force-locking connection is increased. The arrangement of the walls 8 of the exemplary embodiment shown here additionally has the effect that they delimit the connecting face on both sides, so that the solder 9 cannot leave the space delimited by the walls 8 and therefore the connecting face at which the material bond comes into being is clearly defined.
[0040] FIG. 5 shows a sectional illustration through a fourth exemplary embodiment of a contact 1 according to the invention, which largely corresponds to the second exemplary embodiment of FIG. 3. The difference between the two exemplary embodiments is that here, the wall 8 is not arranged on the contact rod 2 but on the contact piece 3. In principle, a wall 8 can be arranged on the contact rod 2 or the contact piece 3 in all embodiments of the invention. It is also possible to provide one or more walls both on the contact rod 2 and the contact piece 3. In general, however, the material of the contact rod 2 is softer and more flexible than that of the contact piece 3, and therefore a wall 8 on the contact rod 2 allows production of the force-locking connection with a lower pressing force.
[0041] FIG. 6 shows a sectional illustration through a fifth exemplary embodiment of a contact 1 according to the invention, in which the contact piece 3 is inset in the contact rod 2. Such an embodiment can be selected when the coefficient of thermal expansion of the material of the contact piece 3 is greater than that of the material of the contact rod 2. As a result, the contact piece 3 expands during heating to a greater extent than the contact rod 2 does, and therefore the robustness of the force-locking connection is temporarily increased in the course of the production of the material bond. This makes it possible to produce the force-locking connection with a relatively small force, with a larger force acting during the soldering operation and holding the contact piece 3 and contact rod 2 in the desired position relative to one another.
[0042] FIG. 7 shows a sectional illustration through a sixth exemplary embodiment of a contact 1 according to the invention, in which there are provided multiple walls 8 which, however, by contrast with the exemplary embodiment of FIG. 4, all delimit the connecting face at the same end. Such arrangements of walls 8 are, of course, also possible in the other embodiments shown. In the sixth exemplary embodiment, trenches 12, each of which runs next to one of the walls 8, are additionally provided. Here, each trench 12 is arranged on that side of the associated wall 8 that is remote from the contact side 14. This has the advantage that the wall 8 becomes flexible and some of the material of the wall 8 can be displaced into the associated trench 12 when the force-locking connection is being produced, as a result of which, for the one part, the contact surface area of the force-locking connection is increased and at the same time the maximum contact pressure of the force-locking connection is reduced and advantageously distributed over the surface area. This makes it possible to realize a better force-locking connection while applying a reduced pressing force. Of course, such a trench 12 or multiple trenches 12 can also be provided in the other exemplary embodiments shown.
[0043] FIG. 8 shows an exemplary embodiment of the method according to the invention for producing a contact according to the invention, which method begins with a starting step S0 and continues with a step S1, in which a contact rod is provided. In step S2, a matching contact piece is provided. In step S3, solder is placed between the contact rod and the contact piece. Steps S1, S2 and S3 can generally be carried out in any desired sequence or at the same time. Then, in step S4, the contact rod and contact piece are connected in a force-locking connection by applying a pressing force along the longitudinal axis. In step S5, the contact rod and contact piece are materially bonded, and this operation can comprising sub-steps of evacuating a vacuum soldering furnace and heating the vacuum soldering furnace. The method ends with a final step S6 after cooling down the vacuum soldering furnace and finishing the contact.
[0044] The invention has been explained in more detail on the basis of drawings of exemplary embodiments. The exemplary embodiments serve merely for better understanding in this respect and are not intended to have a limiting effect on the invention defined exclusively by the following patent claims.
LIST OF REFERENCE SIGNS
[0045] 1 Contact [0046] 2 Contact rod [0047] 3 Contact piece [0048] 4 Movement direction [0049] Bellows [0050] 6 Shield [0051] 7 Ceramic housing [0052] 8 Wall [0053] 9 Solder [0054] 10 Formation [0055] 11 Passage [0056] 12 Trench [0057] 13 Longitudinal axis [0058] 14 Contact face [0059] 100 Vacuum interrupter
