| 摘要 |
537,940. Multi-contact electric switches. BRITISH THOMSON-HOUSTON CO., Ltd. April 29, 1940, No. 7673. Convention date, April 29, 1939. [Class 38 (v)] An electric switch comprises a housing with a recess in which is a substantially central rotary member with a plurality of cams operating six spring contacts arranged in two groups of three at different levels and co-operating with fixed contacts carried by pairs of arms extending from three terminal members disposed round the rotary cam member, the two arms of each terminal member being at different levels. As shown, a housing 21 is formed with front and rear recesses 23, 22, respectively containing the switch positioning means and the fixed and movable contacts. Terminal members 27, 35, 40 secured to the rear wall of the housing are each provided with a pair of integral arms carrying the fixed contacts, respectively 29 and 30, 36 and 37, 41 and 42, the two arms on each member being at different levels and extending in different directions. The movable contacts are carried by six U-form spring blades, arranged in pairs, the members of each pair being arranged in opposite directions and at different levels. Each blade is spot-welded, or otherwise secured to the leg of a strap-member disposed in a groove in a wall of the recess 22. Thus, the blades 49, 54 are secured respectively to the leg 47 of a strap-member 46 and the leg 53 of a strap-member 51. The strap-members are exposed on the rear face of the housing, and in the case shown the straps 46, 51 are connected by a strip 56, and a shorting strip 70 connects three of the remaining straps 59, 71. 75. The contact blades are operated by cam discs 83 of insulating material secured on a shaft 84 with intervening separating plates 86, sliders 81 being secured to the blades and resting on the cams. The shaft 81 carries in the recess 23 a star-wheel engaged by rollers on two spring-connected pivoted arms in order to position it in its operative positions. Diagrams show the use of the switch in connection with a three-wire supply circuit and a two-element heater for giving five degrees of heating and an "off" position. In a modification, the contact arm 36 of the member 33 is replaced by a contact arm secured to the cover and connected to the terminal 27 the shorting strip 56 is omitted, and the strip 70 connects only the terminal straps 59, 75. Diagrams show the use of this form for controlling three oven-heater elements connected to a threewire supply circuit to give four degrees of heating and an " off " position. |
