| 摘要 |
1,255,223. Vacuum switches. MITSUBISHI DENKI K.K. 11 March, 1969, No. 12791/69. Heading H1N. In a vacuum switch of the type comprising a cylindrical metallic housing 10 defining an arc extinguishing chamber 16, a pair of stationary and movable contacts 34, 35, disposed in the housing and carried by conductive rods 32, 33, and an electrically insulating chamber 26 and/ or 27 secured to at least one end of the chamber 16 and defined by a hollow cylinder 22 or 23, respectively, at least one contact includes a low melting-point metal, and the housing 10 is of stainless steel, preferably a non-magnetic stainless steel of austenitic structure consisting of at least 10% by weight of chromium, at least 6% by weight of nickel, and the balance iron. Each cylinder 22, 23, is closed at one end by a flat or cup-shaped metallic cover 24, 25, and is secured at the other end to an apertured metallic end plate 12, 13, welded to the housing 10 so that the end of the housing and the edge of the plate are substantially flush. The end plates engage the adjacent end portions of the housing 10 over a relatively large axial extent to reinforce the housing, different methods of achieving this being described in Figs. 1 and 3, and in Figs. 2, 4, 5, 6 (not shown). The contacts 34, 35, are of copper and include, as the low melting- point metal, metals such as bismuth, tellurium, antimony or silver. The thickness of the housing 10 is in a specific relationship to its outside diameter. As described and claimed in Specification 19271/69, stainless steel shields 36, 37, 38, 39, are provided to prevent metal vapors from entering chambers 26, 27, and to prevent thermal radiation from overheating the insulating cylinders 22, 23. The shields are flat or cup-shaped, and shield 36 may have a hollow cylindrical portion 48 projecting into chamber 26, Fig. 3. The assembly of the switch is described, an exhaust tube 40 being connected to a vacuum pump (not shown) and heating devices 62, 64, Fig. 7 (not shown), including gas burners, being provided for heating the entire assembly and the metallic housing 10 only, respectively. Device 64 may be a high frequency heater. Alternatively heat is generated by bringing contacts 34, 35, together and passing a high current therethrough. |
