| 摘要 |
1,207,941. Valves. ALLIS-CHALMERS MFG. CO. 15 Jan., 1969 [25 Jan., 1968], No. 2421/69. Heading F2V. [Also in Division F1] A stop valve 30 is disposed in the discharge duct 29 of a blower 27 supplying air to the sight tube 18 of a radiation pyrometer 23 fitted to a rotary kiln 10, and a flow sensing pivoting vane 36 operates a switch 40 to cause subsequent closure of the valve if the duet becomes blocked. The closure of switch 40 starts timers T 1 , T 2 . After an interval, timer T 1 changes over switch contacts 48, 49, to reverse the polarity of the current supplied to a solenoid 32. This causes the stop valve 30 to close. After a further interval the timer T 2 opens a switch 46 to re-set the timers T 1 , T 2 . The valve is thus opened and remains open if the blockage has been removed, since the vane pivots to open switch 40. If, however, the switch 40 remains closed, the timers are re-energized and the cycle is repeated. A pulse counter 45 moves each time the timers are energized, and after a predetermined number of pulses a switch 47 is closed to lock the valve in the open position and operate an alarm 66. |
