GB2232442A - Pumps with pivotably mounted rotor blades - Google Patents

Abstract

A centrifugal pump comprises a rotor having blades pivotable about axis P parallel with axis of rotation A of rotor. The blades comprise an integral blade portion 24 and shaft 26 carried by bearing members (34), assembled with the rotorbody by push-fit assembly methods. Stop means, eg. a collar 44 keyed to shaft 26, prevents rotation of the blade portion 24 beyond extreme positions at either side of a radius of the rotor passing through the pivot axis P and at the same angle relative to the radius for either direction of the rotor. The collar 44 has projections (50, Fig. 5) which engage a projection (52, Fig. 5) of the rotor to limit pivotting of the blade. Irrespective of the direction of rotation of the rotor (10), fluid is drawn through an axial inlet (16, Fig. 2) and delivered through peripheral outlets (20, Fig. 1). Collar (44) can be exchanged for one in which projections (50) are at different angles to one another to change the extreme positions of the blade portion 24. <IMAGE>

Description

PUMPS This invention is concerned with improvements in or relating to pumps and is especially concerned with centrifugal pumps and rotors therefor.

In our copending Patent Application No. 8712187 (Publication No. 2205128) is described a reversible centrifugal pump comprising a rotor driveable in rotation in both directions about an axis by a motor, the rotor being mounted in a casing having an inlet and a peripheral outlet for fluid to be pumped, the rotor comprising impellor blades which are pivotted to the rotor to rotate relative thereto between two extreme positions, there being stop means preventing rotation of the blades beyond said extreme position. In the pump described by way of example the stop means comprises pins extending through the rotor parallel to the rotor axis and positioned to abut the blades.Although the pump described by way of example in said copending Patent Application has been found to operate reasonably satisfactorily in practice, the presense of pins projecting into the flow path of fluid passing through the pump tends to interfere with flow of fluid.

Furthermore, the manufacture and assembly of the pump as described by way of example in our aforementioned Patent Application is relatively inefficient and expensive.

One of the objects of the present invention is to provide an improved centrifugal pump.

In one aspect the invention may be considered to provide a centrifugal pump comprising a rotor adapted to be driven rotatably about an axis in either direction, a casing in which the rotor is mounted, the casing having an axial inlet and a peripheral outlet for fluid to be pumped, the pump further comprising impellor blades each mounted on the rotor by a pivot for pivotal movement about a pivot axis parallel with the axis of the rotor, the pivot being positioned radially outwardly of the axis of the rotor with the blade extending generally outwardly therefrom, each blade being provided with stop means adapted to engaged a portion or portions of the rotor whereby to prevent rotation of the blade beyond two extreme positions one at either side of a radius of the rotor passing through the pivot.

In another aspect the invention may be considered to provide a rotor for a centrifugal pump comprising a body and a plurality of impellor blades each mounted on the rotor by a pivot for movement about a pivot axis parallel with the axis of rotation of the rotor, each pivot being positioned radically outwardly of the axis of the rotor with the blade extending generally outwardly therefrom, each blade being provided with stop means adapted to engage a portion or portions of the rotor whereby to prevent rotation of the blade beyond two extreme positions one at either side of a radius of the rotor passing through the pivot.

Preferably in a pump and rotor in accordance with the invention the blade in both extreme positions is disposed at the same angle relative to said radius for either direction of rotor rotation to pump fluid from the inlet through the outlet; the flow rate is thus similar irrespective of the direction of rotation of the rotor.

This is especially important in swimming pool cleaners in which a single reversible motor can be used both to propel the cleaner to and fro along the bottom of a swimming pool and also to operate the pump of the cleaner.

Preferably in a pump and rotor in accordance with the invention each blade comprises a blade portion and a shaft integral therewith, preferably moulded from a suitable plastics material, the shaft providing said pivot and being mounted for said pivotal movement in bearing means supported by the rotor in openings in the rotor. Conveniently each bearing means comprises two bearing members which are a push-fit in the associated opening in the rotor, being introduced one from either end of the opening. Conveniently, also, each shaft is a push-fit in the associated bearing members and comprises a collar at an end portion remote from the blade portion adapted to engage one of the bearing members to retain the blade in the bearing means.Suitably said end portion remote from the blade portion is adapted to flex inwardly so that the collar can readily pass through the bearing members on insertion.

Preferably in a pump and rotor in accordance with the invention said portion or portions of the rotor to be engaged by the stop means comprise(s) a projection or projections into the opening and said stop means are provided on the shaft and rotate therewith. Preferably the stop means is adapted to be removably mounted on the shaft whereby the stop means may be removed and a further stop means mounted on said shaft thus to change the extreme positions. Conveniently said stop means comprises a collar which is slidably introduced onto the shaft and retained in engagement with the shaft for rotation therewith, for example by inter-engaging key and keyway provided on the shaft and collar; the collar in this instance comprises two angularly spaced outward projections positioned to engage said projection or projections in the said opening.Suitably in addition to the blade being moulded of plastics material, the rotor body, the bearing members, and the collar are also moulded of suitable plastics material. This material should be dimensionally stable in the conditions to which it will be subjected, for example withstanding the chlorinated water commonly used in swimming pools where the pump is to be used in a swimming pool cleaner, and must have adequate strength.

There now follows a detailed description to be read with reference to the accompanying drawings, of a pump and rotor embodying the invention. It will be realised that this pump and rotor have been selected for description to illustrate the invention by way of example.

In the accompanying drawings: Figure 1 is a front view of a pump embodying the invention; Figure 2 is a view in section on the line 2-2 of figure 1; Figure 3 is a rear plan view of a rotor of the pump shown in figure 1; Figure 4 is an enlarged sectional view on the line 4-4 of Figure 3; Figure 5 is a fragmentary sectional view on the line 5-5 of figure 4 showing the mounting of an impellor blade; and Figure 6 is an exploded view of the rotor of the illustrative pump.

The illustrative pump comprises a rotor 10 adapted to be driven rotatably about an axis A in either direction (as indicated by the arrows D1 and D2). The rotor 10 is mounted for rotation in a casing 12 and is adapted to be driven by a waterproof electric motor (not shown) carried in a housing 14 in the casing 12. The rotor 10 is in driving engagement with a drive shaft of the motor and is received on the drive shaft and configured in such a way as to militate against water entering the motor housing around the drive shaft.

Furthermore, the drive shaft is provided with seals also acting to prevent ingress of water to the interior of the motor.

The casing 12 has an axial inlet 16 through which liquid to be pump is drawn into the casing 12 by rotation of the rotor 10 during operation of the pump. The illustrative pump has an inlet manifold (not shown) leading to the axial opening 16; suitably a filter may be connected to an inlet end portion of the manifold 18 so that water being drawn into the casing 12 is filtered by the filter: this arrangement is especially suitable for use in a swimming pool cleaner.

The casing 12 has peripheral outlets 20 for fluid to be pumped.

The pump further comprises impellor blades 22. The impellor blades 22 of the illustrative apparatus each comprise a blade portion 24 and an integral shaft 26: the blades 22 are injection moulded of a suitable plastics material for example a polycarbonate resin which is both strong and which has sufficient resistance to attack by the liquid to be pumped, so that the blades 22 are durable. The rotor 10 has a generally cylindrical body portion 28 from which projects a connecting portion 30 adapted to be connected to the output shaft of the motor and an approximately conical portion 32 opposite the portion 30 adapted to project axially into the opening 16 to assist streamline flow of fluid through the opening 16 into the casing 12. Any desired number of blades 22 may be carried by the rotor 10: in the illustrative apparatus there are three blades.

The blades 22 are mounted in bearing means comprising bearing members 34 supported by the rotor in recesses 38 at opposite ends of openings 36 passing through the body 28 parallel with the axis A. The bearing members 34 are a push-fit in the recesess 38 and are arranged to be introduced into the recesses 38 from opposite faces of the rotor body 28. The outer surface of the members 34 is substantially flush with the outer surface 40 of the rotor body 28.

The shaft 26 is a push-fit in the associated bearing members 34 and comprises a collar 42 at an end portion remote from the blade portion 24 adapted to engage one of the bearing members 34 to retain the blade 22 in the bearing means. The shaft 26 carried by the bearing members 34 provides a pivot havin an axis P parallel with the axis A, for the blade 22.

A collar 44 is slidably received on the shaft and is located thereon relative to the blade portion 24 by engagement of an inwardly projecting key 46 with a keyway portion 47 of a slot 48 formed at said end portion of the shaft 26 remote from the blade portion 24. Thus the collar 44 is retained in engagement with the shaft for rotation therewith. The collar 44 comprises, in addition, two angularly spaced outward projections 50 positioned equiangularly one at either side of the blade portion 24 (see figure 5). The projections 50 are positioned to engage a projection 52 from the body 28 of the rotor into the opening 36 between the recesses 38. The projection 52 is positioned on a radius extending between the axis A of rotation of the rotor 10 and the pivot axis P of the blade 22.Thus the projections 50 provide stop means of the blade 22 adapted to engage the projection 52 of the rotor 10 to prevent rotation of the blade portion 24 beyond two extreme positions, one at either side of a radius of the rotor passing through the pivot axis P, the extreme positions being disposed at the same angle relative to said radius for either direction of rotor rotation whereby to pump fluid from the inlet 16 through the outlets 20.

Two opposite slots 48 are in fact provided in said end portion of the shaft 26, one of the slots 48 being longer than the other and providing said keyway portion 47 at the end portion of the slot 48 nearest the blade portion 24. Provision of two opposed slots in this manner permits the extreme end portion of the shaft 24 to flex inwardly as the shaft is pushed through openings in the bearing members 34 so that the shaft 26 is a push-fit in the bearing members 34. When the collar 42 passes beyond the outer face of the bearing members 34 remote from the blade portion 24, the resilience of the shaft allows the end portion of the shaft to spring apart thus engaging the collar with the outer face of the bearing member 34.

The illustrative rotor can thus be assembled with the blades 24, bearing members 34 and collar 44 relatively quickly and simply. The collar can be exchanged in simple manner merely by removing the rotor 10 from the casing, and withdrawing the shaft 26 from the bearing members 34 by exerting a force in an axial direction as indicated by the arrow W in Figure 4. The extreme end portion of the shaft 26 readily passes through the opening in the bearing members 34 remote from the blade portion 24 but engagement of the collar 44 with the other bearing member 34 causes the other bearing member 34 to be withdrawn from the opening 26 in the direction of the arrow W. Access can thus be gained to the collar 44 and the collar can be slidingly removed from the shaft 26. A new collar can be fitted by reversing these actions.Provision of a new collar with the outward projections 50 having a different angular relationship to one another is used to change the extreme positions which the blade portion 24 of the blade 22 may adopt. This can be useful where it is wished to change the flow rate of the pump. Alternatively the collar 44 may be placed on the shaft having been rotated through 1800 end-over-end so that the projections 50may have a different reation to the blade portion 24 so that it adopts different extreme positions.

The ready exchange of the collars 44 is also useful in initial assembly of a pump. For example, the AC mains frequencies in some countries differ from those in other countries. It is possible to use the same AC motor in some cases, for mains supplies having different AC mains frequencies but the rotation speed of the motor will be correspondinly changed: thus a motor which at a mains frequency of 50 Hz would rotate at about 2800 r.p.m. may rotate at 60 Hz at a rate of about 3360 r.p.m. As each pump is designed to act at maximum efficiency and safety at a particular flow rate such a change in rotation rate could impaire the efficiency of the pump. However, by changing the orientation of the blade portion of the blade 22, the pumping rate may also be varied. Thus by replacing the collar 44 with a collar having the projections 50 in different angular relationship to one another, the extreme positions of the blade portions 24 may be adapted to provide the same pumping rates for a motor operated at 60 Hz as would be provided by the same motor operating at 50 Hz with the original collar in position. This allows pumps to be produced for sale in countries having different cycle AC mains using identical components (with the manufacturing advantages accruing from bulk production and ordering) apart, possibly, from the collar where different collars may be produced for various different mains frequencies.

The illustrative pump is also very simple and quick to assemble, as the components of the rotor push-fit to assemble them, thus giving advantages from increased production efficiency.

Claims (11)

1. A centrifugal pump comprising a rotor adapted to be driven rotatably about an axis in either direction, a casing in which the rotor is mounted, the casing having an axial inlet and a peripheral outlet for fluid to be pumped, the pump further comprising impellor blades each mounted on the rotor by a pivot for pivotal movement about a pivot axis parallel with the axis of the rotor, the pivot being positioned radially outwardly of the axis of the rotor with the blade extending generally outwardly therefrom, each blade being provided with stop means adapted to engaged a portion or portions of the rotor whereby to prevent rotation of the blade beyond two extreme positions one at either side of a radius of the rotor passing through the pivot.

2. A pump according to Claim 1 wherein the blade in both extreme positions is disposed at the same angle relative to said radius for either direction or rotor rotation to pump fluid from the inlet through the outlet.

3. A pump according to either one of Claims 1 and 2 wherein each blade comprises a blade portion and a shaft integral therewith, the shaft providing said pivot and being mounted for said pivotal movement in bearing means supported by the rotor in openings in the rotor.

4. A pump according to Claim 3 wherein said stop means are provided on said shaft, and rotate therewith and wherein said portion or portions of the rotor comprises or comprise a projection or projections into the opening.

5. A pump according to Claim 4 wherein the stop means is adapted to be removably mounted on said shaft whereby the stop means may be removed and a further stop means mounted on said shaft whereby to change said extreme positions.

6. A pump according to any one of the preceding Claims wherein said stop means comprises a collar which is slidably introduced onto said shaft and retained in engagement with the shaft for rotation therewith, the collar comprising two angularly spaced projections positioned to engage said projection or projections into said opening.

7. A pump according to Claim 6 wherein the shaft and collar comprise an interengaging key and keyway by which the shaft and collar are connected for rotation.

8. A pump according to any one of Claims 3 to 7 wherein each bearing means comprises two bearing members which are a push-fit in the associated opening in the rotor, one from either end of the opening.

9. A pump according to Claim 8 wherein each shaft is a push-fit in the associated bearing members and comprises a collar at an end portion remote from the blade portion adapted to engage one of the bearing members to retain the blade in said bearing means.

10. A centrifugal pump constructed arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.

11. A rotor for a centrifugal pump comprising a body and a plurality of impellor blades each mounted on the rotor by a pivot for movement about a pivot axis parallel with the axis of rotation of the rotor, each pivot being positioned radially outwardly of the axis of the rotor with a blade portion extending generally outwardly therefrom, each blade being provided with stop means adapted to engage a portion or portions of the rotor whereby to prevent rotation of the blade portion beyond two extreme positions one at either side of a radius of the rotor passing through the pivot.