CENTRIFUGAL PUMP WITH REINFORCED PLASTIC IMPELLER WHEEL

Abstract

A centrifugal pump has a housing forming a chamber having intake and output ports and a plastic lining in the chamber An impeller wheel in the chamber is formed by a hub rotatable about an axis, a rear disk projecting radially from the hub, a front disk projecting radially from the hub and offset axially from the rear disk, and radial vanes extending axially between the disks. The hub, disks, and vanes are formed of a high-strength material such as metal and carries a coating on outer surfaces of the hub, disks, and vanes of a plastic of lower strength than the material.

Claims

1. A centrifugal pump comprising: a housing forming a chamber having intake and output ports; a plastic lining in the chamber; and an impeller wheel in the chamber and formed by a hub rotatable about an axis, a rear disk projecting radially from the hub, a front disk projecting radially from the hub and offset axially from the rear disk; radial vanes extending axially between the disks, the hub, disks, and vanes being formed of a high-strength material; and a coating on outer surfaces of the hub, disks, and vanes of a plastic of lower strength than the material.

2. The centrifugal pump defined in claim 1, wherein the front disk is cohesively or positively connected to the rear disk by the vanes.

3. The centrifugal pump defined in claim 2, wherein the hub, disks, and vanes are integral.

4. The centrifugal pump defined in claim 2, wherein the hub, disks, and vanes are unitary.

5. The centrifugal pump defined in claim 3, wherein the hub, disks, and vanes are unitarily formed of cast metal.

6. The centrifugal pump defined in claim 1, wherein the plastic coating on the hub, disks, and vanes, is of uniform thickness.

7. The centrifugal pump defined in claim 1 wherein the hub, disks, and vanes have surface formations interfitting with the plastic coating.

8. The centrifugal pump defined in claim 7 wherein the formations are grooves or holes.

9. The centrifugal pump defined in claim 1, wherein the hub is configured to be rotated by a drive shaft.

10. The centrifugal pump defined in claim 1, wherein the lining and the coating are of the same plastic.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0013] The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

[0014] FIG. 1 is an axial section through an impeller wheel according to the invention; and

[0015] FIG. 2 is a section through the impeller wheel according to the invention at the level of its vanes.

SPECIFIC DESCRIPTION OF THE INVENTION

[0016] A centrifugal pump has an unillustrated two-part housing shown in broken lines at 6 and joined at a plane 9 that extends through a chamber 10, so that the inner walls of the chamber 10 and of intake and output ports 11 and 12 can be provided with little effort with a lining 13 of a plastic that protects the inner walls of both the chamber and the ports 11 and 12. The housing 6 is made of metal or of a hard plastic composite. A fully fluorinated, partially fluorinated, or non-fluorinated plastic is used as the plastic of the lining 13 in order to obtain high-quality corrosion or purity protection of the pressure- and power-transmitting pump parts.

[0017] An impeller wheel 1 enclosed in the plastic-lined chamber 10 has a hub 8 from which a circular rear disk 2 extends radially. The hub 8 is formed with a blind normally threaded bore 7 that receives one end of a shaft 14 of an electric motor 15 or magnetic coupling. Furthermore, the impeller wheel 1 has a front annular front disk 3 that is of frustoconical shape and forms a central annular suction opening 4 aligned with the intake port 4. The plate 3 is connected by radially extending but arcuate vanes 5 to the rear disk 2 so that rotation about an axis A of the shaft 15 draws a fluid (normally a liquid) radially inward through the ports 11 and 4 and expels it radially outward between the vanes 5 from the port 12.

[0018] The hub 8, rear disk 2, front disk 3, and vanes 5 are unitarily formed as a core from cast metal or from a high-strength plastic or plastic composite of greater strength than the liner 13 of the pump chamber 10. The one-piece structure formed by this hub 8, disk 2, disk 3, and vanes 5 is covered on all outer surfaces by a coating or layer 16 of a plastic of less strength and/or hardness than that forming the hub 8, disks 2 and 3, and vanes 5, for instance the same as forms the lining 13.

[0019] In one embodiment, the parts forming the hub 8, disks 2 and 3, and the vanes 5 are separate but integrally connected together. Preferably, however, all of these parts are made of the same metal or of the same high-strength plastic and are connected to each other cohesively or positively, so that the hub 6, disks 2 and 3, and vanes 5 are unitarily interconnected and thus together form a supporting, one-piece framework made of metal or high-strength plastic that is surrounded, particularly extrusion-coated, by the plastic coating 16 of the impeller wheel 1 or a fully or partially fluorinated plastic such as perfluoroalkoxy alkane (PFA) or polytetrafluoroethylene (PFAPVDF) is preferably used. The coating 16 is of uniform thickness and closely and uniformly fits to the contours of the hub 8, disks 2 and 3 and vanes 5 partially or completely true to form.

[0020] In order to achieve an intimate bond between the outer plastic coating 16 of the impeller wheel 1 and the cores, each of the parts 8, 2, 3, and 5 of the wheel 1 has mounting bores and/or clamping grooves into which engages the plastic of the coating 16 of the impeller wheel 1. One such grip formation is shown as a plastic-filled hole 17 through the rear disk 2.