US1837887A - Device for regulating the output of centrifugal pumps - Google Patents

Description

Dec. 22, 1931. v sc pT- 1,837,887

DEVICE FOR REGULATING THE OUTPUT OF CENTRIFUGAL PUMPS Filed Dec. 13, 1929 Patented Dec. 22, 1931 v- UNITED STATES PATENT OFFICE IPAUL SCHMIDT, E MUNICH,

DEVICE FOR REGULATING- THE OUTPUT OF CENTItIFUGAL PUMLPS Application filed December 13, 1929, Serial No. 413,841, and in Germany June 20, 1929.

Until quite recently regulation of the output of centrifugal pumps was confined to throttling down large pump outputs, by means of sluice valves or the like, to give the desired pressure or the desired quantity of water. Only just lately have attempts been made to apply a scientific form of regulation, using a type of construction known in the art of water turbine building and comprising a guide device fitted with Finks rotatable blades. i

The present invention has for its object to provide a regulating arrangement which is better suited to the peculiar properties of cenn trifugal pumps and which, therefore, operates to better hydraulicefiect than the arrangement of this-kind known hitherto. To

this end, according to the invention, it is proposed to provide, for the regulation of output in centrifugal pumps, devices which render it possible to vary the size of the blade surfaces of the rotor wheel in such a manner that an increase in the blade surfaces results in an increase in output while asreduction in these surfaces gives a reduction in output.

The invention has particular reference to the arrangement, ontheblade wheels of centrifugal pumps, of separate surface members or bodies which are kept in place, either individually or collectively, by means ofposi' tioning devices and are moved thereby upon the relatively immovable blade surfaces proper. The devices according to the invention will effect regulation in a manner which is favourable-from the hydraulic standpoint if,when the blade surfaces are varied, the profile of thepassa es remains unchanged.

The advantage 0% maintaining the profile of the passages constant is particularly ap-' parent in the fact that the relative retards." tion which the liquid, in general, undergoes in the guide passages, takes place at all times under the optimum conditions determined by the original construction. The general advention reside pre-eminently inthe fact that regulation of output is effected-at those constructional parts of the centrifugal pumps which transfer energy to the water, whereas the types of construction known heretofore vantages of the devices according to the inset out to regulate the output by adjusting the guide apparatus, that is to say, adjusting a device having no direct connection with the exchange of energy between pump and liquid. Thus, in accordance with the invention, the size-of the working surface itself determines the amount of energy to be imparted to the fluid 'and one can speak of a directness of regulation whichis not a property of the known constructions. Consequently the devices according to the invention give better hydraulic action even at a triflingtechnical expenditure. Predominantly the regulation I of output is carried out in such a manner that the blade surfaces are increased or diminished in a direction at right angles to that of the current of liquid. In this connection it appears that the profile of the passages (regarded in the direction of the flowing liquid) remains practically unchanged, so that, by these means, the same conditions of flow are practically ensured throughout the whole range of adjustment. Furthermore, the new arrangement is also concerned with a variation of the blade surfaces in the direction of the flowing liquid.

The accompanying drawing shows dia: grammatically, in a section through the axis ofthe main shaft, one example of a radial pump constructed according to the invention and providing for variation of the-blade surface .in a direction perpendicular to the path of the fluid. The upper half of the drawing shows the output regulator in a posi- {3011} diiferent from'that shown in'the lower In this constructional example the rotor wheel or impeller 1, to which fluid is admitted from both sides, is mounted in a casing 2. The rotor wheel is secured to the driving shaft 4 by means of two hubs or bosses 3. The devices for varying the blade surface consist, according to the invention, of surface members or blade sections 5 which are carried by the walls or shrouds 6 of the wheel 1 and can be pushed in axial direction over theblade surfaces of the said wheel. The surface members or blade sections 5 are part of 'the impeller blades of the pumps and each cooperates with a. corresponding blade on. the impeller 1 to form the active areas of the impeller blades, and thus byadjustment of the shrouds 6 in an axial direction, the active areas of the impeller blades are increased or decreased depending upon the direction of I movement of the shrouds 6 to vary the output of the pump. The walls or shrouds, 6 of the wheel are respectively connected each by means of ribs 7 and a hub 8 to one of a pair of sleeves 9 extending over the shaft 4. The sleeves 9 extend out of the casing 2 into the open on both sides and are held by positioning devices 10. These positioning devices 10 can be shifted in the axial direction in any ing can easily be arranged for pumps with diagonal flow wheels or even for axial flow pumps. In devices appropriate to these conditions, so far as concerns enlargement of the blades rigidly carriedby. said hub, a shroud rotatable with and movable along said shaft, and blade sections carried by said shroud and cooperating with the hub carried blades to formvthe active blade area of the impeller, whereby adjustment of the shroud along the shaft will vary the active blade area of the impeller, said blade sections conforming in shape to said blades whereby variation of the active blade surfaces may be varied without affecting the profile of the impeller passages.

4. In a centrifuga'l'pump, a shaft, an impeller embodying a hub keyed to said shaft, blades rigidly carried by said hub, a sleeve slidably mounted on said shaft and rotatable therewith, a shroud for the impeller connected to said sleeve, and blade sections carried by said shroud and cooperating with the hub carried blade sections to form the active blade area of the pump whereby adjustment of the sleeve will vary the active blade area of the impeller.

In testimony whereof I have signed my name to this specification.

PAUL SCHMIDT.

blade surfaces in the direction of flow of the fluid, the devices constitute an exact combina tion of the basic blade and passage profile, since the contacting and relatively displaceable surfaces run only within'the path de' fined by the profile. For rotors with purely axial admission the rule must also be followed that the whole of the contact surface of the parts of the blade surfaces which are relatively movable is formed as a helical surface'with a constant pitch.-

What is claimed is:

1. In a centrifugal pump, an impeller embodying a hub, blades, and a shroud, blade sections carried bysaid shroud and cooperating with said blades to form the active blade surfaces of the impeller, said shroud being. adjustable in an axial direction for varying the active blade-areas of saidimpeller.

2. In a centrifugal pump, a shaft, an impeller embodying a hub keyed to said shaft, bladesrigidly carried by said hub, a shroud rotatable with and movable along said shaft, and blade sections carried by said shroud and cooperating with the hub carried blades to form the active blade area of the impeller,

whereby adjustment of the shroud along the shaft will vary the active blade area of the impeller.

3. In a centrifugal pump, a' shaft, an impeller embodying a hub keyed to said shaft,

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