Coupling device and centrifugal pump making use of same

Claim 2

Device for coupling a body with a drive shaft in rotation, comprising: an annular groove made in one of these elements, viz. body or drive shaft, opposite a surface of revolution of the other of these elements; an annular joint means made of elastic material, located partly in said groove and having two axial faces at least partly clear of said body and said drive shaft for exposure to pressure of a fluid medium; means for creating a pressure differential at opposite sides of said joint means, said means including a pressure generating means driven by said body for subjecting a fluid medium to pressure varying with the drive between the body and the shaft, so arranged as to create a difference in pressure between the fluid medium in contact with one axial face of said joint means and the fluid medium in contact with the other axial face of said joint means, whereby an axial pressure difference on said joint means presses said joint means against a side of said groove to produce a radial expansion of said joint means and thereby to complete and ensure the seal between said body and said drive shaft and then to ensure the integration in rotation of the body and the drive shaft.

Claim 3

Coupling device as claimed in claim 1, wherein the aforesaid surface of revolution is cylindrical, wherein also the difference in pressures of said fluid medium on the respective axial faces of said joint means varies from substantially zero at the beginning of said drive to progressively higher values as said drive continues, thereby progressively effecting said integration in rotation, wherein also, at the beginning of rotation, a slight axial displacement of the body with respect to the shaft is possible, and wherein said shaft is supported in bearings integral with a structure which includes two axial support pieces opposite which are disposed two axial edges of said body disposed so that said fluid medium is present in the clearances therebetween and serving to guide said body into a suitable position just prior to said integration.

Claim 4

Coupling device as claimed in claim 1, wherein the groove is made in the body.

Claim 5

Coupling device as claimed in claim 1, wherein, in manner known per se, the joint has at assembly a radial clearance with at least one of the two elements between which it is interposed.

Claim 6

Centrifugal pump comprising the coupling device as claimed in claim 1, and comprising also at least one impeller wheel, constituting said body, bearings for said shaft, and a structure supporting said bearings and having also means establishing a chamber for said impeller wheel and conduit means providing communication for said fluid medium between the periphery of said impeller wheel with a chamber, one of the walls of which is constituted by that face of said joint means which is on the side of said joint means opposite the suction zone of the wheel.

Claim 7

Contrifugal pump as claimed in claim 5, wherein a said impeller wheel is so constituted that the difference in the pressure on axial sides of said joint means varies from a subStantially zero value at the beginning of said drive to progressively higher values as said drive continues, thereby progressively effecting said integration in rotation, wherein also at the beginning of the rotation, a slight axial displacement of the body with respect to the shaft is possible, wherein also said shaft is supported in bearings integral with a structure, including two axial support peices opposite which are disposed two axial edges of said body, disposed so that said fluid medium is present in the clearances therebetween and serving to guide said body into a suitable position for integration with said shaft, wherein also said centrifugal pump comprises at least two impeller wheels corresponding to at least two compression stages, wherein also said conduit leading from the periphery of the impeller wheel of a previous stage is constituted at least in part by the suction channel of the wheel corresponding to the next following stage, wherein also said pump comprises a volute chamber in which at least one of said impeller wheels is disposed, said volute chamber constituting the structure with which the bearings of the shaft are integral and which is provided with two opposite axial faces, forming support pieces, between which said impeller wheel is disposed.