| 摘要 |
1,183,964. Swell compensators for suction-pipe dredgers. MINERAAL TECHNOLOGISCH INSTITUUT. Sept.13, 1967 [Nov.28, 1966], No.41774/67. Heading G3R. A swell compensator for the suction-pipe of a drag suction dredger, of the type in which the rope between the winch and the pipe passes over a vertically-movable pulley subject to a constant force through a piston, cylinder and compressed air arrangement, is provided with a control system for automatically operating the winch when the pulley is displaced a predetermined amount beyond its normal operating position, such operation returning the pulley to this position. The pulley (K Fig. 1 not shown) carries a plate 1 movable vertically therewith and positioned to actuate switches 2--5 either by physical contact or by magnetic effect if the switches are of the reed type and the plate varies the strength of a magnetic field. Switches 2--5 connect an integrating circuit comprising D.C. amplifier 18, resistor 16 and capacitor 17 to positive and negative D.C. supplies 6, 7 through resistors 8--11, which are chosen so that the outer switches pass higher currents than the inner ones. When the pulley and plate 1 oscillate about the normal median position the output voltage from amplifier 18 oscillates about zero, but should the plate 1 be displaced from this position (due to a change in the depth of the sea bed) a resultant voltage will build up at a rate dependent on the number of switches closed in the displacement direction and on the duration of closure, Fig. 3 (not shown). Each time this resultant voltage exceeds a threshold value, a pulse is produced by one or other of trigger circuits 23, 24, the pulse or a series of pulses being fed to a delay circuit 33 or 34 which produces a continuous correction signal commencing with the leading edge of the (first) pulse and ending a predetermined time after the trailing edge of the (last) pulse, Fig. 4 (not shown), this extension of the correction signal ensuring that the plate is completely returned to the median position. The correction signal controls the winch-driving motor or cable-winding motors through NOR-gates 36 or 37 and amplifiers 38 or 39, the gates 36, 37 being inter-connected to prevent simultaneous operation of the winch winding and unwinding circuits. A further protection circuit 35 prevents winch operation when the apparatus is first switched on.
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