| 摘要 |
1,249,028. Electromagnetic switches. TEXAS INSTRUMENTS Inc. 23 July, 1969 [23 July, 1968], No. 37105/69. Heading H1N. [Also in Division H2] An A.C. motor for driving a garbage disposal unit is started in opposite directions upon successive closures of a master switch. Means responsive to a predetermined level of motor current disconnects a starting winding after each switch-closure, and means responsive to a higher current-value reconnects the starting winding without motor reversal. When line switch 53 is open, coil 21 is deenergized, whereby movable contacts 77 drop away from fixed contacts 45, 46, 48, 50. At the same time, follower 79 engages fixed cam 5 in position C. When switch 53 is closed, the follower 79 is lifted by coil 21 and turned by engagement with the angled ends 95 of tines 91 and cam 93. The contacts 77 then connect the pairs 46, 48, and 45, 50, whereby the running and starting windings 65, 67, are energized, the follower 79 being in position A. After the motor reaches full speed, the current through winding 65 and coil 21 is reduced to permit the follower 79 to drop to the position B, since coil 21 no longer holds up the core piece 83. However, in view of the flux-concentrating ring 33, the core piece 111 and cam 93 are held down. Contacts 77 re-opened to disconnect the starting winding 67. When the coil is next de-energized, by operating manual switch 53 or by overload current opening breaker 41, the assembly 68 drops so that follower 79 steps around to a new angular position. Upon the next application of power the contacts 77 move to connect pairs 45, 46 and 48, 50, during the starting operation and then re-open, under diminished current conditions, to disconnect the starting winding. The windings 65, 67 are connected in the opposite sense, whereby the motor runs in reverse with respect to the previous operation. In the event of an overload insufficient to trip breaker 41, the coil 21 pulls up core 83 to reclose contacts 77, whereby the starting winding is re-connected. Follower 79 is withheld from cam 5 so that the contact assembly does not rotate. When this type of overload condition terminates, the follower 79 drops to the position B which cuts out the starting winding while leaving the motor running without change of direction. The contact assembly 68 is formed by crossarm 69, follower 79, rockable conductive segments 73 carrying the contacts 77, post 81, core 83, and spring 87. Another spring 86 engages washer 105 to apply a downward force on core piece 83. The stepping cam 93 has armature 111 and is forced upwardly by spring 101. When the coil 21 is energized, the contact assembly 68 is pulled up by core 83 and cam 93 is forced down by armature 111. The cross-arm 69 has lugs 71 located in slots formed in segments 73, a rivet 75 being inserted in each lug. |
