Thomson coil driven switch assembly with lightweight plunger

Abstract

An electrical switch assembly includes a contact element to be moved towards a further contact element for generating an electrical connection; and a drive for moving the contact element; wherein the drive includes a plunger with a connection member interconnected with the contact element; wherein the plunger includes a mechanical structure with a top side to which the connection member is connection, and a bottom side opposite to the top side; wherein the drive includes a Thomas coil for moving the plunger via an electrically conducting top face, which is provided on the top side and an electrically conducting bottom face, which is provided on the bottom side. The mechanical structure includes at least one channel between the top side and the bottom side, the at least one channel extending transverse to a movement direction of the plunger. Furthermore, the mechanical structure fills less than 50% of a volume between the top side and the bottom side.

Claims

1. An electrical switch assembly, comprising: a contact element to be moved towards a further contact element for generating an electrical connection; and a drive for moving the contact element; wherein the drive comprises a plunger with a connection member interconnected with the contact element, wherein the plunger comprises a mechanical structure with a top side to which the connection member is connected, and a bottom side opposite to the top side, wherein an electrically conducting top face is on the top side and an electrically conducting bottom face is on the bottom side; wherein the drive comprises a Thomson coil for moving the plunger via the electrically conducting top face and the electrically conducting bottom face; wherein the mechanical structure comprises at least one channel between the top side and the bottom side, the at least one channel extending transverse to a movement direction of the plunger; wherein the mechanical structure fills less than 50% of a volume between the top side and the bottom side.

2. The electrical switch assembly of claim 1, wherein a cross section through the mechanical structure parallel to the bottom side has an area less than 20% of the area of the bottom side.

3. The electrical switch assembly of claim 1, wherein the mechanical structure comprises a top plate at the top side and a bottom plate at the bottom side.

4. The electrical switch assembly of claim 1, wherein the top side and the bottom side are interconnected with struts; wherein at least some of the struts are inclined with respect to the top side and the bottom side.

5. The electrical switch assembly of claim 1, wherein for at least some of the struts, the extension direction of the struts is directed towards the connection member.

6. The electrical switch assembly of claim 1, wherein the mechanical structure has an irregular pattern; and/or wherein struts of the mechanical structure are arranged in an irregular pattern.

7. The electrical switch assembly of claim 1, wherein the plunger comprises a cavity, in which a sensor is arranged.

8. The electrical switch assembly of claim 1, wherein at least a part of the mechanical structure is obtained by additive manufacturing methods.

9. The electrical switch assembly of claim 1, wherein at least a part of the mechanical structure is obtained by machining the channels and/or cavities into a solid block of material; wherein the mechanical structure comprises a plurality of channels running parallel to each other and parallel to the top side and the bottom side.

10. The electrical switch assembly of claim 1, wherein the mechanical structure and the connection member are one-piece.

11. The electrical switch assembly of claim 1, wherein the connection member comprises at least one arm protruding orthogonal from the top side and having holes for connecting the contact element.

12. The electrical switch assembly of claim 11, wherein at least one of the arms is hollow.

13. The electrical switch assembly of claim 1, wherein the drive comprises a bistable suspension for holding the plunger in a top position and a bottom position; wherein the mechanical structure comprises attachment plates, which are aligned orthogonal to the top side and the bottom side and each of which has a hole for connecting the bistable suspension-.

14. The electrical switch assembly of claim 1, wherein the bistable suspension comprises a link connected to at least one of the attachment plates and to a piston movable in a cylinder orthogonal to the movement direction of the plunger.

15. The electrical switch assembly of claim 1, further comprising: a second drive for moving the further contact element towards the contact element.

16. The electrical switch assembly of claim 2, wherein the mechanical structure comprises a top plate at the top side and a bottom plate at the bottom side.

17. The electrical switch assembly of claim 2, wherein the top side and the bottom side are interconnected with struts; wherein at least some of the struts are inclined with respect to the top side and the bottom side.

18. The electrical switch assembly of claim 2, wherein for at least some of the struts, the extension direction of the struts is directed towards the connection member.

19. The electrical switch assembly of claim 2, wherein the mechanical structure has an irregular pattern; and/or wherein struts of the mechanical structure are arranged in an irregular pattern.

20. The electrical switch assembly of claim 2, wherein the plunger comprises a cavity, in which a sensor is arranged.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subject-matter of the invention will be explained in more detail in the following text with reference to exemplary embodiments which are illustrated in the attached drawings.

(2) FIG. 1 schematically shows a switch assembly according to an embodiment of the invention.

(3) FIG. 2 schematically shows a cross-section of a drive of a switch assembly according to an embodiment of the invention.

(4) FIG. 3 shows a cross-section of a plunger of a switch assembly according to an embodiment of the invention.

(5) FIG. 4 shows a perspective view of the plunger of FIG. 3.

(6) FIG. 5 shows a cross-section of a plunger of a switch assembly according to a further embodiment of the invention.

(7) FIG. 6 shows a perspective view of the plunger of FIG. 5.

(8) The reference symbols used in the drawings, and their meanings, are listed in summary form in the list of reference symbols. In principle, identical parts are provided with the same reference symbols in the figures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(9) FIG. 1 shows an electrical switch assembly 10, which comprises two terminals 12, which may be electrically interconnected and disconnected with contact elements 14, which are moved towards each other or away from each other with the aids of two drives 16.

(10) The contact elements 14 are provided on paddles 18, which may be seen as a part of the respective contact element 14 and/or which are aligned parallel to each other, when the paddles 18 connected to one drive 16 are moved away from the paddles 18 connected to the other drive 16, the contact elements 14 are moved away from each other and the electrical switch assembly 10 opens. Vice versa, when the paddles 18 connected to one drive 16 are moved towards the paddles 18 connected to the other drive 16, the contact elements 14 are moved towards each other and the electrical switch assembly 10 closes. In FIG. 1, the electrical switch assembly 10 is shown in a closed position.

(11) The components 12, 14, 16, 18 of the electrical switch assembly 10 may be accommodated in a housing 20, which may be filled with an isolating gas, such as SF6.

(12) FIG. 2 shows a drive 16 in more detail. The drive comprises a housing 22 enclosing a chamber 24. A plunger 26 is arranged within the chamber 24 and held by a bistable suspension 28. The plunger 26 is guided in the housing 22 and movable along a direction D from a first or top position (as shown in FIG. 2) to a second or bottom position (as indicated in FIG. 2).

(13) The plunger 26 comprises a connection member 30 and a base 32 which is wider than the connection member 30. The base 32 comprises a mechanical structure 34 with a top side 36 and a parallel bottom side 38, with both are aligned orthogonal to the direction D.

(14) The connection member 30 is attached to the top side 36. With the connection member 30, the plunger 26 is connected to the paddles 18. The paddles 18 and the connection member 30 extend through an opening 40 in the housing 22.

(15) The bistable suspension 28 comprises two pistons 42 movable along cylinders 44 in a direction orthogonal to the direction D. The pistons 42 are pushed towards chamber 24 by springs 46. Each piston 42 is connected to the plunger 26 with a link 47. Each link 47 is formed by a substantially rigid rod, which is, at a first end, rotatably connected to its piston 42 and, at a second end, rotatably connected to a side of the plunger 26.

(16) The plunger 26 comprises an electrically conducting top face 48 at the top side 36 and an electrically conducting bottom face 50 at the bottom side 38, which both are ring-shaped and surround an axis of the plunger 26 (which axis runs along line D).

(17) For moving the plunger 26, the drive 16 comprises a Thomson coil 52, which comprises a top coil 54, which is provided in the housing 22 opposite to the top side 36 of the plunger 26, and a bottom coil 56, which is provided in the housing 22 opposite to the bottom side 38 of the plunger 26.

(18) For example, when the plunger 26 is in the first position and a current pulse is sent through the top coil 54, a mirror current is generated within the top face 48, which leads to a repulsive force that accelerates the plunger 26 away from the top coil 54 to the second position. Analogously, the plunger can be moved from the second to the first position with a current pulse through the bottom coil 56.

(19) FIGS. 3 and 4 show an embodiment of a plunger 26, which is machined from a solid block of metal material, such as an Al alloy. The connection member 30 and the mechanical structure 34 are made in one-piece by machining the block of metal material.

(20) The mechanical structure 34 is made by machining channels 58 in form of bores and cavities 60 into the block of metal material. The mechanical structure has been machined in such a way that 50% or more material has been removed from the material between the top side 36 and the bottom side 38.

(21) Some of the channels 58 may be aligned in parallel to the top side 36 and the bottom side and/or orthogonal to the movement direction D. These channels 58 may only have an opening towards a side of the mechanical structure 34.

(22) Furthermore, some channels and/or bores 58 and/or cavities 60 may have an opening towards the bottom side 38. In a cavity or pocket 60, which may have an opening towards the bottom side 38, one or more sensors 61 may be housed, which may measure the position and the acceleration of the plunger 26. This may provide useful data for lifetime prediction of the plunger 26.

(23) Between these bores, small bars and/or posts 62 are formed, which interconnect the top side 36 with the bottom side 38. The overall area of these bars and/or posts 62 may be smaller than 20% of the area of the top side 36 or the bottom side 38.

(24) At opposite sides of the plunger 26, attachment plates 64 are provided in the mechanical structure, which are aligned orthogonal to the top side 36 and the bottom side 38 and/or parallel to the movement direction D. These attachment plates 64 have a hole 66, to which a link 47 of the bistable suspension 28 may be connected.

(25) The electrically conducting top face 48 and the electrically conducting bottom face 50 are provided in a depression 68 in the top side 36 and the bottom side 38. The electrically conducting faces 48, 50 are not shown in FIGS. 4 to 6. The electrically conducting faces 48, 50 may be coated onto the respective side 38, 38 of the mechanical structure 34 and/or may be plates attached in the depressions 68, for example by welding, gluing, soldering, etc. The electrically conducting faces 48, 50 may be made of Cu.

(26) The depressions 68 are formed in a top plate 70 and bottom plate 72 of the mechanical structure 34, which are formed, since no or less material has been removed from the machined block.

(27) To the top plate 70, the connection member 30 is connected, which is formed of four arms 74, 78, which all have holes 76 orthogonal to the movement direction D and/or in parallel to the top side 36 and the bottom side 38. The two outer arms 74 are smaller than the two inner arms 78.

(28) FIGS. 5 and 6 show an embodiment of a plunger 26′, which is made by 3D printing, for example with a Ti alloy. As the plunger 26 of FIGS. 3 and 4, the plunger 26′ also has a connection member 30 with four arms 74, 78 and a mechanical structure 34 with a top plate 70 and a bottom plate 72. The inner arms 78 are hollow members, which are composed of outer walls, in which the holes 76 are provided.

(29) Analogously to FIGS. 3 and 4, the mechanical structure 34 also has a top plate 70 and a bottom plate 72. Furthermore, attachment plates 64 with holes 66 are present at opposite sides of the mechanical structure.

(30) The space between the top plate 70 and a bottom plate 72 is filled with a network of struts 80 that interconnect the top plate 70 and a bottom plate 72. The struts are designed in such a way that more than 50%, or more than 80%, of the volume between the top side 36 and the bottom side 38 is empty, i.e. not filled with the material of the mechanical structure 34.

(31) Furthermore, the area of a cross section through the mechanical structure in the middle between the top side 36 and the bottom side 38 is less than 20% of the area of the top side 36 or the bottom side 38.

(32) As shown in FIG. 5, struts 80 may join and/or may split up into two or more struts 80 between the top plate 70 and a bottom plate 72. At least some of the struts 80 may have a continuously changing shape and/or maximal diameter along their extension direction.

(33) Some of the struts 80 may be aligned in parallel to the movement direction D of the plunger 26. Other struts 80 may be inclined and may be aligned towards the connection member 30, such that forces are absorbed in an optimal way.

(34) Between the struts 80 several channels 58 run in a transverse direction through the plunger 26′. These channels 58 may be aligned in parallel to each other and/or may have openings 82 towards a narrow side of the plunger 26.

(35) While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art and practising the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or controller or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

LIST OF REFERENCE SYMBOLS

(36) 10 electrical switch assembly 12 terminal 14 contact element 16 drive 18 paddle 20 housing 22 housing 24 chamber 26 plunger 26′ plunger 28 bistable suspension 30 connection member 32 base 34 mechanical structure 36 top side 38 bottom side D moving direction 40 opening 42 piston 44 cylinder 46 spring 47 link 48 electrically conducting top face 50 electrically conducting bottom face 52 Thomson coil 54 top coil 56 bottom coil 58 channel/bore 60 cavity 61 sensor 62 bar, post 64 attachment plate 66 hole 68 depression 70 top plate 72 bottom plate 74 arm 76 hole 78 arm 80 strut 82 opening