| 摘要 |
934,311. Stuffing-box substitutes. A. R. WILFLEY & SONS Inc. Dec. 19, 1961 [Aug. 22, 1961], No. 45398/61. Class 122 (5). The shaft 25, Fig. 1, of a centrifugal pump is sealed by means comprising a flexible diaphragm 60 which is secured to the pump casing and sealingly engages a sleeve 62 on the shaft when it is stationary but which is withdrawn therefrom by vacuum created by expeller blades 38 on the pump impeller 35 when the shaft rotates above a given speed, the shaft then being sealed by the expeller blades 38. The diaphragm 60, which may be of rubber, plastic or metal, is clamped at its opposite edge portions 75 and 80 to the impeller housing and to a collector housing 26 respectively and has a portion 86 which, when the shaft is at rest, is urged by the liquid pressure in space A into contact with an insert 87 in the sleeve 62. The space B is vented to atmosphere through an outlet 70 in the housing 26. When the shaft rotates the pressure in space A is reduced due to the action of blades 38 and the sealing contact between 86 and 87 is broken. Flanges 42 and 45 on the impeller engage grooves in the housing to form labyrinth seals. Additional means, which may be electrical, mechanical, hydraulic or pneumatic, may be provided to assist the movement of the diaphragm 60. In the modification shown in Fig. 3, a plate 105 is connected to the diaphragm 100 and to the plunger 110 of a solenoid 108. When the switch for the motor driving the impeller shaft 25 is closed, after a delay by a timing device 115, the solenoid 108 is energized and the sealing means opened. When the motor is shut-off the solenoid is de-energized and, after a suitable time delay, the diaphragm is returned to its sealing position. In further modifications, the diaphragm is additionally moved into and out of sealing contact by magnetic means controlled by the pump motor. In still further modifications, the diaphragm is additionally moved out of sealing contact against spring action by a piston and cylinder device actuated by hydraulic or pneumatic pressure supplied from a pump driven from the impeller shaft. In the embodiment shown in Fig. 9, the diaphragm is in the form of a metallic bellows 270 which is connected to a rod 281 attached to a plate 290 which, when the shaft rotates, is moved axially against a spring 288 by centrifugal weights 292 to move the bellows out of contact with the insert 275. Specification 643,247 is referred to.
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