| 摘要 |
<p>840,671. Centrifugal pumps. ASHWORTH, N. I. Nov. 14, 1957 [March 26, 1957], No. 9799/57. Class 110 (1). In a centrifugal pump of the kind in which the shaft is vertical and enters the top of the pump casing through a sealing-passage which.permits fluid from the pump casing to escape to discharge between the shaft and the wall of the sealing passage and seal the sealing passage against intake of air and so that the mixture of liquid and abrasive being pumped does not reach a shaft bearing, means are provided for ejecting the mixture from the upper end of the sealing- passage by means of a member rotating with the impeller shaft and creating a stirring or centrifugal action, or both. The centrifugal pump shown draws in a mixture of abrasive and water from a sump 13 through a conduit 14. The driving-shaft is not provided with a packing gland, and liquid passing up the annular space between the shaft and a sleeve 8 and then down between the sleeve 8 and an annular hood 11 carried by the shaft is returned to the sump by way of a passage 12. Liquid is contained in the passage 12 up to the sump liquid level A, thereby preventing air from entering the pump by way of the annular space between the shaft and the sleeve 8. The boss 17 of the impeller passes freely through an opening in the pump casing, the clearance space around the boss communicating only with the space between the shaft and the sleeve 8. Since there is no packing gland or bearing to hold abrasive against the shaft, the shaft is not subjected to a grinding action. The pump casing and impeller may be provided with abrasive-resistant linings. According to the Provisional Specification, the shaft is provided with a thrower disc having a depending flange, to deflect escaping abrasive mixture back to the sump.</p> |
