RU1783171C - Screw-centrifugal pump - Google Patents

Abstract

Usage: when designing a device for protection against cavitation of low-pressure centrifugal pumps. SUMMARY OF THE INVENTION: a screw with blades is mounted on the shaft with a clearance and axial movement. The screw is placed on a shaft nozzle conical with different angles of inclination. The gaps are filled with a deformable filler. The nozzle and the inner surface of the auger with a reciprocal conical bevel are made with rounded channels and protrusions, restrictive and end stops, equipped with permanent magnets facing each other with the same poles. The limit stop mounted on the shaft is made with radial cutouts. 2 ill.

Description

The invention relates to the field of pump engineering and can be used in the design of devices for protection against cavitation of low-pressure centrifugal pumps.

A centrifugal pump is known, which contains an upstream wheel with a hub, on both sides of which there are friction disks and a squeezing elastic element rigidly mounted on the shaft and located between the working and upstream wheels, and the friction disks are fixed at the ends of the hub. This constructive solution provides protection of the centrifugal pump from cavitation, but only in developed cavitation modes, i.e. with intense evolution of the gas phase.

The closest technical solution is a screw centrifugal pump comprising a housing, an upstream auger with vanes mounted on a shaft with clearance and axial movement, and an impeller.

The disadvantage of this technical solution is the insufficient protection against cavitation of the pump in all modes of its operation.

The purpose of the invention is to increase the efficiency of protecting the pump from cavitation by varying the screw speed.

In FIG. 1 shows a screw centrifugal pump, a longitudinal section; in FIG. 2 is a section AA in FIG. 1.

The screw-centrifugal pump (Fig. 1, 2) consists of a screw wheel 1 with blades 2, placed with gaps 5 on a conical different angle of inclination of the nozzle 4 of the shaft 3. The inner surface of the wheel 1 is made with a mating conical bevel 6 and with rounded longitudinal protrusions 7, and the corresponding surface of the nozzle 4 with longitudinal channels 8. The gaps between the wheel 1 and the nozzle 4, the protrusions 7 and the channels 8 are filled with a deformable filler 9. At the ends of the wheel and the nozzle, an end stop 10 and a limit stop 11 are placed, and the stop 11 is provided with radial and vyrefe

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12. The boundary edges of the channels 8 and protrusions, as well as the stops 10.11 and the surface of the wheel 14 and the nozzle 15 are made with elements of permanent magnets 13, which are facing each other with the same poles.

Screw centrifugal pump operates as follows. In the nominal operating mode of the low-pressure centrifugal pump, when the shaft 3 is crossed, the screw wheel 1 with the blades 2 is untwisted, since the torque is transmitted from the conical nozzle A by means of quite sufficient adhesion forces that are formed as a result of the deformable filler 9 being compressed in the gaps 5. If a further increase in the pressure of the pumped liquid occurs, the ECO moves. In this case, the deformable filler 9 under the influence of centrifugal forces, the axial force associated with the fluid pressure, and the inclined parts of the protrusions 7 and the channels 8 discarding the deformable filler to the periphery, further clogs the gaps between the main part of the protrusions 7 and the channels 8, which contributes to the best mechanical adhesion of the wheel 1 and nozzle A. The restriction on movement are, on the one hand, permanent magnets 13. mounted on the end surface of the nozzle 4, and, on the other hand, stops 10 and 11, also equipped with constant m rot 13, facing each other with the same poles. Radial cuts 12 on the stop 11 provide an increase in pressure in the gap 5 (as an impeller), which can significantly reduce volumetric leaks due to the use of unsupported

auger wheels. When the fluid pressure decreases, the wheel 1 moves off under the action of combined forces: gravity, centrifugal forces, as well as the fluid pressure flowing in the gap between the shaft and the wheel. The deformable filler 9 is drawn into the widening gap between the end face, nozzle surface and the inner surface of the wheel. Thereby, the adhesion forces between the protrusions 7 and the channels 8 are reduced, which leads to a slip of the screw wheel 1 relative to the shaft 3. As a result, the screw wheel starts to rotate at a lower angular speed, which means that the static pressure in front of the wheel increases, which provides sufficiently effective protection against cavitation .

Claims (1)

The claims A screw centrifugal pump comprising a casing, an upstream screw with blades mounted on a shaft with a clearance and the possibility of axial movement, and an impeller, characterized in that, in order to increase the efficiency of protection of the pump from cavitation by changing the number of revolutions of the screw, the latter is placed on a conical different angles of inclination of the shaft nozzle, the gaps are filled with a deformable filler, the nozzle and the inner surface of the screw with a conical bevel are made with rounded longitudinal channels and protrusions, restrictions Yelnia and end stops provided with permanent magnets facing each other with the same poles, the limit stop mounted on a shaft formed with radial notches. fas 2.