US 3054355 A
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Description (OCR text may contain errors)
Sept- 13, 1962 R. s. NEELY 3,054,355
Filed April 25, 1961 IN VEN TOR.
3,054,355 Patented Sept. 18, 1952 3,054,355 PUMP vanla Filed Apr. 25, 1961, Ser. No. 105,416 1 Claim. (Cl. 103-117) This invention is .an eccentric type rotary pump having a body of rubber or like elastomer bonded to a driving hub and flexible vanes which are bent by contact with the housing walls as the impeller is rotated. In such pumps, the vanes are deected as cantilever beams and the highest bending moment is .at the root of the blades and is imposed on the bond between the impeller and the hub by producing a stress concentration which has resulted in failures of the bond to the hub. This difculty is overcome by providing the blades with notches or localized weakened sections intermediate the ends so that the bending moment in the blades is moved outward away from the hub.
ln the drawing, FIG. l is an end view of the impeller, FIG. 2 is a section on line 2-2 of FIG. 1 and FIG. 3 is a diagrammatic view showing the behavior of the blades in a pump housing.
In the drawing, 1 indicates the driving hub to be suitably fastened to a drive shaft through keyway 2, and 3 indicates an impeller body of rubber or like elastomer bonded to the outer surface of the driving hub 1 and having a plurality of radially projecting blades 4. For the particular impeller illustrated, which is designed for a cylindrical pump housing, the blades are of rectangular cross section as shown in FIG. 2. The edges 5 and 6 of the blades bear on the end walls 0f the housing and the tips 7 of the blades bear on the peripheral walls of the housing. The hub 1 is ordinarily bonded to the impeller as a part of the molding operation.
FIG. 3 shows the impeller assembled in a pump housing 8 having a peripheral wall 9 eccentric to the axis of the impeller hub and having inlet and outlet openings diagrammatically indicated at 10 and 11. As the impeller is rotated in the direction of the arrow, the blades on the left hand side of the impeller are progressively deflected radially inward, thereby creating a pressure of the outlet 11 while the blades on the right hand side of the impeller are progressively expanded, thereby creating a suction at the inlet 10. For the reverse direction of rotation, 10 would be the outlet and 11 the inlet.
To decrease the stress on the bond between the impeller and the hub, the blades are provided with weakened sections 12 located radially outside the roots 13 of the blades and radially inside the minimum radius from the axis of the hub to the peripheral wall of the pump housing. By this arrangement, the bending stress on the impeller blades is shifted outward away from the hub so that the stress between the impeller and the driving hub is relieved. Heretofore, the bond between the impeller and the hub has been the Weak point in the impeller and numerous expedients have been tried to reinforce or increase the strength of the bond. In the present construction, no attempt is made to reinforce or increase the strength of the bond to the hub. Instead, the points of maximum stress are shifted outward away from the hub and localized in the weakened sections of the blades remote from the hub. While it might be thought that this would unduly weaken the blades, that is not the case. The blades will stand a tremendous .amount of flexing, particularly in water pumps where the blades are water cooled.
The weakened sections 12 are conveniently obtained by notches 15 on opposite sides of the blades. If the impeller were to be run in only one direction, the notches could be on only the trailing side of the blades. Notching on both sides permits the impeller to be run in either direction.
If the notches were omitted, the bending stress would increase from zero at the tips 7 to a maximum at the roots 13. With the notches, the bending stress increases from zero at the tips to a maximum at the notches.
What is claimed as new is:
In a rotary pump, a hub, an impeller having a body of elastomer surrounding and bonded to the hub and flexible blades with the roots thereof integral with the body and projecting radially therefrom with the tips of the blades remote from the body, a pump housing having a peripheral wall eccentric to the axis of the hub, the minimum radius from the axis of the hub to the peripheral Wall of the pump housing being less than the radius from the axis of the hub to the tips of the blades in the unstressed condition, said blades being progressively bent inward by Contact with said peripheral wall as the impeller is rotated in either direction, and said blades having localized weakened sections formed by notches on opposite sides of the blades radially outside the roots of the blades and radially inside said minimum radius.
References Cited in the file of this patent UNITED STATES PATENTS 2,258,371 Wernert Oct. 7, 1941 2,455,194 Rumsey Nov. 30, 1948 2,466,440 Kiekhaefer Apr. 5, 1949 2,599,600 Arnold June 10, 1952 2,648,287 Thoren, et al Aug. 11, 1953 2,663,263 Mayus, et al. Dec. 22, 1953 2,664,050 Abresch Dec. 29, 1953 2,712,792 Snyder July 12, 1955 2,789,511 Doble Apr. 23, 1957 2,911,920 Thompson Nov. 10, 1959 2,976,811 Sully Mar. 28, 1961 FOREIGN PATENTS 1,213,695 France Nov. 2, 1959