Management of contact spots between an electrical brush and substrate

Abstract

Devices for the management of contact spots, partly consisting of surface plating, partly of surface polishing and partly of substrate surface profiling in the form of parallel grooves stretched out in the direction of sliding and/or of isolated asperities. The management of the contact spots is designed to generate, at electrical brush interfaces, a large number of contact spots of pre-determined shapes and distribution that promote low electrical contact resistance and long wear life. Preferably, the substrate is coated with a hard, highly conductive coating that is resistant to wear and chemical attack. The invention is similarly applicable also to electrical switches wherein it will assure reduction of interfacial resistance as well as of sticking forces. Finally, it may also be used for the efficient transfer of heat across interfaces.

1. A device for making electrical connection with an electrical brush having a plurality of current conducting elements, said device comprising:
 a substrate having microscopic surface irregularities; and  , said surface irregularities shaped and dimensioned to provide multiple contact spots to each  plural current conducting element  elements of said plurality of current conducting elements;  
 wherein said surface irregularities are configured to provide contact spots spaced at least  on average less than 100 d on each element of said plurality of  plural current conducting elements, where d is a diameter of each element  an average diameter of the plurality of  current conducting elements.  
 
     
     
       2. The device according to  claim 1 , wherein the surface irregularities comprise a plurality of asperities. 
     
     
       3. The device according to  claim 1 , wherein the surface irregularities comprise a plurality of grooves. 
     
     
       4. The device according to  claim 3 , wherein the plurality of grooves are substantially parallel to each other. 
     
     
       5. The device according to  claim 1 , wherein the surface irregularities comprise a plurality of asperities and grooves. 
     
     
       6. The device according to  claim 5 , wherein the plurality of asperities are within the grooves and between the grooves. 
     
     
       7. The device according to  claim 1 , wherein the substrate comprises a surface material harder than  having a hardness greater than a hardness of the plurality of current conducting elements. 
     
     
       8. The device according to  claim 1 , wherein the surface irregularities comprise a shape and dimension satisfying the following equation:
   2≦r c /d≦10,  
 
       where r c  is an average radius of the surface irregularities, and d is an average diameter of the plurality of current conducting elements. 
     
     
       9. The device according to  claim 1 , wherein the substrate comprises a surface material selected from the group consisting of titanium nitride and metal nitride. 
     
     
       10. The device according to  claim 1 , wherein the substrate comprises a surface material selected from the group consisting of brass, copper, nickel, stainless steel, titanium, copper alloy, nickel alloy, titanium alloy and chromium. 
     
     
       11. The device according to  claim 1 , wherein the substrate comprises a surface material selected from the group consisting of noble metals, silver, gold, rhodium, platinum, iridium, silver alloy, gold alloy, rhodium alloy,  and platinum alloy. 
     
     
       12. The device according to  claim 1 , wherein the substrate comprises a surface material including graphite. 
     
     
       13. The device according to  claim 1 , wherein the surface irregularities comprise laser-etched irregularities. 
     
     
       14. The device according to  claim 1 , wherein the surface irregularities comprise lithography-etched irregularities. 
     
     
       15. The device according to  claim 1 , wherein the surface irregularities comprise mechanically-polished irregularities. 
     
     
       16. The device according to  claim 1 , wherein the surface irregularities comprise metallographic electrolytic-polished irregularities. 
     
     
       17. The device according to  claim 1 , wherein the surface irregularities comprise liquid metal aerosol deposited irregularities. 
     
     
       18. The device according to  claim 1 , wherein, between the surface irregularities, local deviations from strict planarity of the substrate surface do not exceed 20 degrees. 
     
     
       19. The device according to  claim 1 , wherein, between the surface irregularities, local deviations from strict planarity of the substrate surface do not exceed 10 degrees. 
     
     
       20. The device according to  claim 1 , wherein, between the surface irregularities, local deviations from strict planarity of the substrate surface do not exceed 0.60 degrees. 
     
     
       21. The device according to  claim 1 , wherein, between the surface irregularities, local deviations from strict planarity of the substrate surface do not exceed 0.01 degrees. 
     
     
       22. The device according to  claim 1 , wherein, between the surface irregularities, local deviations from strict planarity of the substrate surface do not exceed 0.024 degrees. 
     
     
       23. An electrical connection system, comprising:
 an electrical brush having a plurality of current conducting elements; and  
 a substrate having microscopic surface irregularities shaped and dimensioned to provide multiple contact spots to each  plural current conducting element  elements of said plurality of current conducting elements;  
 wherein said surface irregularities are configured to provide contact spots spaced at least  on average less than 100 d on each element of said plurality of  the plural current conducting elements, where d is a diameter of each element  an average diameter of the plurality of current conducting elements.  
 
     
     
       24. The system according to  claim 23 , wherein the brush is configured to slide against the substrate and the plurality of current conducting elements are oriented parallel to a sliding direction of the brush. 
     
     
       25. The system according to  claim 23 , wherein the plurality of current conducting elements comprise a plurality of metal fibers. 
     
     
       26. The system according to  claim 23 , wherein the plurality of current conducting elements comprise a plurality of metal foils. 
     
     
       27. The system according to  claim 23 , wherein the plurality of current conducting elements comprise a plurality of metal fibers and foils. 
     
     
       28. The system according to  claim 27 , wherein the brush includes at least one of 1) a support fiber and 2) a support foil, and said surface irregularities comprise at least one groove configured to receive the at least one of the support fiber and support foil. 
     
     
       29. The system according to  claim 23 , wherein the plurality of current conducting elements comprise at least one arc-resistant metal fiber having a diameter which is less than an average diameter of the plurality of current conducting elements. 
     
     
       30. The system according to  claim 29 , wherein the arc-resistant metal fiber comprises at least one of a stainless steel metal fiber and a tungsten metal fiber. 
     
     
       31. The system according to  claim 23 , wherein the plurality of current conducting elements comprise at least one fiber including a protective coating with noble metals. 
     
     
       32. The claim  system according to claim  31    23 , wherein said protective coating is selected from the platinum group  the brush comprises a cross-resistance. 
     
     
       33. The system according to  claim 23 , wherein the brush comprises a cross-sectional shape. 
     
     
       34. The system according to  claim 23 , wherein the brush comprises corrugated metal foils. 
     
     
       35. The system according to  claim 23 , wherein the brush comprises a foot print shape dimensioned to reduce arcs. 
     
     
       36. A method of making an electrical connection device comprising:
 providing an electrical  electric brush having a plurality of current conducting elements; and  
 forming microscopic surface irregularities on a substrate to produce multiple contact posts  spots to each  plural current conducting element  elements of said plurality of current conducting elements;  
 wherein said surface irregularities are configured to provide contact spots spaced at least  on average less than 100 d on each element of said plurality of  the plural current conducting elements, where d is a diameter of each element  an average diameter of the plurality of current conducting elements.  
 
     
     
       37. The method according to  claim 36 , further comprising:
 orienting the plurality of current conducting elements to be parallel to a sliding direction of the brush.  
 
     
     
       38. The method according to  claim 36 , further comprising:
 orienting the plurality of current conducting elements to be at an angle to a sliding direction of the brush.  
 
     
     
       39. The method according to claim  34    36 , wherein the forming step forms the surface irregularities by laser etching. 
     
     
       40. The method according to  claim 36 , wherein the forming step forms the surface irregularities by etching in combination with lithography. 
     
     
       41. The method according to  claim 36 , wherein the forming step forms the surface irregularities by mechanical relief polishing. 
     
     
       42. The method according to  claim 36 , wherein the forming step forms the surface irregularities by metallographic electrolytic polishing. 
     
     
       43. The method according to  claim 36 , wherein the forming step forms the surface irregularities by deposition of a liquid metal aerosol. 
     
     
       44. The method according to  claim 36 , wherein the forming step forms the surface irregularities by mechanically cutting the substrate with a pre-shaped tool. 
     
     
       45. The method according to  claim 36 , wherein the forming step forms the surface irregularities to satisfy the following equation:
   2≦r c /d≦10,  
 
       where r c  is an average radius of the surface irregularities, and d is an average diameter of the plurality of current conducting elements. 
     
     
       46. A device for making electrical connection with an electrical brush having at least one  a plurality of current conducting element  elements, said device comprising:
 a substrate having microscopic surface irregularities; and , said surface irregularities shaped and dimensioned to provide plural contact spots with the at least one  plurality of current conducting element  elements,  
 wherein dimensions of the surface irregularities are in the order of magnitude of a dimension of the  at least one current conducting element to be electrically connected with the device; and 
 wherein said surface irregularities are configured to provide contact spots spaced at least  on average less than 100 d on each element of said plurality of  the plural current conducting elements, where d is a diameter of each element  an average diameter of the plurality of current conducting elements.  
 
     
     
       47. The device according to  claim 46 , wherein the dimensions of the surface irregularities are on the order of magnitude of 20 μm. 
     
     
       48. The device according to  claim 46 , wherein the surface irregularities comprise grooves which are substantially parallel to a sliding direction of the electrical brush. 
     
     
       49. A substrate for making electrical connection with an electrical brush, said substrate comprising:
 a plurality of microscopic asperities provide in a surface of the substrate; and said asperities having a density (D) in the range of: 
   2500/cm 2 ≦D≦10 7 /cm 2 ,  
 
 where the density (D) is defined as a number of asperities per square centimeter.  
 
     
     
       50. The substrate according to  claim 49 , further comprising a plurality of grooves. 
     
     
       51. The substrate according to  claim 50 , wherein the plurality of grooves are substantially parallel to each other. 
     
     
       52. The substrate according to  claim 50 , wherein the plurality of asperities are within the grooves and between the grooves. 
     
     
       53. The substrates according to  claim 50 , wherein adjacent grooves of the plurality of grooves has  have a spacing (λ) is  in the range of:
   10 μm≦λ≦1000 μm.  
 
     
     
       54. The substrate according to  claim 50 , wherein a width of a respective groove of the plurality of grooves is within the inclusive range of 10 μm and 200 μm. 
     
     
       55. The substrate according to  claim 50 , wherein a depth of a respective groove of the plurality of grooves is within the inclusive range of 10 μm and 1 μm. 
     
     
       56. The substrate according to  claim 50 , wherein a depth of a respective groove of the plurality of grooves is within the inclusive range of 10 μm and 200 μm. 
     
     
       57. The substrate according to  claim 49 , wherein a respective asperity of the plurality of asperities has a surface radius of curvature (r c ) in the range of:
   20 μm≦r c ≦2 mm.  
 
     
     
       58. The substrate according to  claim 50 , wherein a respective groove of the plurality of grooves has a surface radius of curvature (r c ) in the range of:
   20 μm≦r c ≦2 mm.  
 
     
     
       59. The substrate according to  claim 49 , further comprising a surface material selected from the group consisting of titanium nitride and metal nitride. 
     
     
       60. The substrate according to  claim 49 , further comprising a surface material selected from the group consisting of brass, copper, nickel, stainless steel, titanium, copper alloy, nickel alloy, titanium alloy and chromium. 
     
     
       61. The substrate according to  claim 49 , further comprising a surface material selected from the group consisting of noble metals, silver, gold, rhodium, platinum, iridium, silver alloy, gold alloy, rhodium alloy, and platinum alloy. 
     
     
       62. The substrate according to  claim 49 , further comprising a surface material including graphite. 
     
     
       63. A substrate  device for making an electrical connection with an electrical brush, said substrate , comprising:
 an electrical brush; 
 a plurality of microscopic grooves provided in a surface of the substrate and having sidewalls for contacting to the electrical brush and thereby making the electrical connection; and  
 adjacent grooves of the plurality of grooves having a spacing (λ) in a range of: 
   10 μm≦(λ)≦1000 μm.  
 
 
     
     
       64. The substrate  device according to  claim 63 , wherein a width of a respective groove of the plurality of grooves is within the inclusive range of 10 μm and 200 μm. 
     
     
       65. The substrate  device according to  claim 63 , wherein a depth of a respective groove of the plurality of grooves is within the inclusive range of 10 μm and 1 mm. 
     
     
       66. The substrate  device according to  claim 63 , wherein a depth of a respective groove of the plurality of grooves is within the inclusive range of 10 μm and 200 μm. 
     
     
       67. The substrate  device according to  claim 63 , wherein a respective groove of the plurality of grooves has a surface radius of curvature (r c ) in the range of:
   20 μm≦r c ≦2 mm.  
 
     
     
       68. The substrate  device according to  claim 63 , wherein the plurality of grooves are substantially parallel to each other. 
     
     
       69. The substrate  device according to  claim 63 , further comprising a plurality of asperities. 
     
     
       70. The substrate  device according to  claim 69 , wherein the plurality of asperities are within the grooves and between the grooves. 
     
     
       71. The substrate  device according to  claim 69 , wherein the plurality of asperities has a density (D) in the range of:
   2500/cm 2 ≦D≦10 7 /cm 2 ,  
 where the density (D) is defined as a number of asperities per square centimeter.  
 
     
     
       72. The substrate  device according to  claim 69 , wherein a respective asperity of the plurality of asperities has a surface radius of curvature (r c ) in the range of:
   20 μm≦r c ≦2 mm.  
 
     
     
       73. The substrate  device according to  claim 63 , further comprising a surface material selected from the group consisting of titanium nitride and metal nitride. 
     
     
       74. The substrate  device according to  claim 63 , further comprising a surface material selected from the group consisting of brass, copper, nickel, stainless steel, titanium, copper alloy, nickel alloy, titanium alloy and chromium. 
     
     
       75. The substrate  device according to  claim 63 , further comprising a surface material selected from the group consisting of noble metals, silver, gold, rhodium, platinum, iridium, silver alloy, gold alloy, rhodium alloy and platinum alloy. 
     
     
       76. The substrate  device according to  claim 63 , further comprising a surface material including graphite. 
     
     
       77. A device for making an electrical connection, comprising:
 an electrical brush;    a plurality of microscopic grooves provided in a surface of the substrate and having curved bottom surfaces for contacting to the electrical brush and thereby making said electrical connection; and    adjacent grooves of the plurality of grooves having a spacing (λ) in a range of: 
     10  μm≦(λ)≦ 1000  μm.