Centrifugal pump

Abstract

A sealless-type centrifugal pump includes a casing that forms a pump chamber having a liquid inflow port and an outflow port, an impeller disposed in the pump chamber and rotatably supported by a pivot bearing, and a magnetic coupling device including a driven permanent magnet built into the impeller and a driving magnet that rotationally drives the driven permanent magnet through a partition. The impeller supported in the direction of the rotation axis with respect to the casing is driven by the magnetic coupling device, and pressure is applied to liquid introduced from the direction of the rotation axis through the inflow port to send the liquid through the outflow port in a radial direction. The magnetic coupling device is disposed on a line inclined from an impeller rotating surface to the inflow port side toward the center of the rotation axis.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims benefit of Japanese Applications No. 2010-021222 filed in Japan on Feb. 2, 2010 and No. 2010-021223 filed in Japan on Feb. 2, 2010, the contents of each of which are hereby incorporated by their reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a centrifugal pump that applies pressure by driving an impeller by magnetic coupling, and in particular, to a centrifugal pump suitable for liquid such as chemical solutions containing fine particles, and liquid such as chemical solutions that tend to seize.[0004]2. Description of Related Art[0005]Conventionally, general pumps have a shaft seal mechanism (shaft seal unit) to prevent fluid in a pump chamber from leaking outside from a shaft and to prevent sucking in of air or the like from outside. Practical shaft seal mechanisms include gland packing, labyrinth or mechanical seals, etc., which are selected depending on...

AI Technical Summary

Benefits of technology

[0011]The present invention is made in consideration of the above-described circumstances, and it is an object thereof to provide a centrifugal pump that needs no shaft seal mechanism and has no leakage. In particular, an object of the present invention is to provide a centrifugal pump with a configuration that is suitable for liquid such as chemical solutions containing fine particles, and liquid such as chemical solutions that tend to seize, and moreover, that can easily be reduced in size.

[0014]With the centrifugal pump according to the first aspect of the present invention, since the pivot bearing includes the pivot shaft located at the center of the rotation axis of the impeller and the bearing portion, at the casing side, provided at the axial center line of the inflow port; and because the magnetic coupling device is disposed on the line inclined from the impeller rotating surface to the inflow port side toward the center of the rotation axis, the magnetic coupling device is disposed in a state in which it is inclined from the impeller rotating surface. Accordingly, thrust depending on the inclination angle acts on the pivot bearing due to the magnetic force of the magnetic coupling; therefore, the pivot shaft is pushed against the bearing portion by the thrust. That is, since the magnetic coupling device is disposed on the line inclined to the inflow port side toward the center of the rotation axis, the magnetic force of the magnetic coupling device is decomposed into a thrust component that pushes the pivot shaft in the direction of the rotation axis and a radial component that acts outward in the direction of the impeller rotating surface, and therefore, the thrust that acts on the pivot bearing stabilizes the rotation of the impeller.

[0017]With the centrifugal pump according to the second aspect of the present invention, since the pivot bearing includes a pivot shaft located at the center of the rotation axis of the impeller and two-point supporting bearing portions that support the pivot shaft from both sides on the axial center line of the inflow port; the magnetic coupling device is disposed on a line inclined from an impeller rotating surface to the inflow port side toward the center of the rotation axis; and a through-hole in the direction of the rotation axis is formed at the center of rotation of the impeller, symmetric secondary flows can be formed on both surfaces of the impeller in the direction of the rotation axis of the impeller, which can therefore balance the axial thrust, thus reducing the load on the pivot bearing.

[0019]According to the present invention described above, since the magnetic coupling device is disposed on the line inclined to the inflow port side toward the center of the rotation axis, so that the magnetic force of the magnetic coupling device generates thrust that pushes the pivot shaft in the direction of the rotation axis, the thrust that acts on the pivot bearing stabilizes the rotation of the impeller, thereby making it possible to easily provide a leak-free compact centrifugal pump without using the shaft seal mechanism.

[0020]Alternatively, since the magnetic coupling device is disposed on the line inclined to the inflow port side toward the center of the rotation axis, the impeller is stably supported by the two-point supporting pivot bearing, and the through-hole in the direction of the rotation axis is formed at the center of rotation of the impeller, symmetric secondary flows can be formed on both surfaces of the impeller in the direction of the rotation axis of the impeller. Therefore, the axial thrust that acts on the impeller and the pivot shaft is balanced in the direction of the rotation axis, which can reduce a load that acts on the stable two-point supporting pivot bearing, thereby making it possible to easily provide a leak-free compact centrifugal pump without using the shaft seal mechanism.

Problems solved by technology

Meanwhile, centrifugal pumps equipped with a shaft seal mechanism have problems with the occurrence of leakage from a shaft seal component, the occurrence of wear and friction, and limited heat-resistant temperature and pressure resistance.