| 摘要 |
977,250. Toothed gearing; valves. E. WICHMANN, and R. SCHMINKE. Aug. 16, 1963 [Aug. 24, 1962], No. 32474/63. Headings F2Q and F2V. [Also in Division H2] Closure of switch 25 in the circuit of contactor 23 energizes electric motor 2 to close valve 22. At the beginning of downward movement of slide 21, switch 27 is closed to short-circuit limit switch 10, but, after the slide leaves the top position, the circuit of contactor 23 is maintained only by the switch 10. If the slide meets an obstacle, gear 3 is moved upwardly against the force of spring 6 so that switch 10 is opened to stop the motor. The same operation takes place when the slide reaches its lower position. The valve is re-opened by actuating switch 26 in circuit with contactor 24. If the slide 21 has jammed in its bottom position, gear 3 moves downward against the force of spring 7 to actuate limit switch 11, which is bridged by switch 28 however. Further movement of gear 3 displaces the limit switch 11 as a unit against the force of spring 15. As soon as the slide 21 is released to begin its upward movement, the switch 11 is released and resumes its control function for the contactor 24. Maximum torque limitation is provided by additional limit switches operated by extreme movement of the gear 3, or by the housings of switches 10, 11, when the latter are moved through a certain distance. The switchactuating element 29 may be replaced by a time device which keeps the switches 27, 28 closed for an initial period. In another embodiment, a link is engaged by a cam on shaft 5 just before slide 21 reaches the top limit position. This displaces switch 10 against spring 14 so that the gear 3 must move a greater distance against the force of spring 6 before it can actuate switch 10. The limit switch will thus respond only to a higher torque during initial movement in the downward direction, Fig. 3 (not shown). |
