GB2115489A - Rotary pumps - Google Patents

Abstract

In a pump comprising a rotor, or "impeller", 16 having flexible vanes on its periphery and made of e.g. an elastomeric material such as neoprene, a fixed annular body 5 is furnished with a single cam 5A or a pair of cams 5A, 5B to deflect the vanes and cheek, or "wear", plates 2, 2B each have a single, or pair of, working-fluid inlet or outlet port(s) PA or PB therein according to the number of cams. The ports communicate with adjacent inlet and outlet ducts, or "manifolds", 1, 14. The pump may comprise two stages, Figs. 2 and 2A (not shown). <IMAGE>

Description

SPECIFICATION Flexible impeller pump This invention relates to flexible impeller pumps.

A flexible impeller pump has an impeller of neoprene or similar elastic material with a number of radial vanes whose tips bear against the periphery of the pumping chamber. A cam located between the inlet and outlet ports causes the vanes to flex so that liquid being carried round by the vanes is squeezed out through the outlet as the cam is encountered and drawn in through the inlet as the vanes leave the cam and become straighter.

We launched the first commercial pumps of this kind over forty years ago and we have been making them to the same basic design ever since.

See for example US Patent 2,189,356. Although improvements in impeller material, shaft seals and casing materials such as stainless steel have widened the application of these pumps, nevertheless the structure of the pump has remained basically unaltered. The body is normally cast from bronze or brass with the cam either integral with the body or separate. Inlet ports extend radially from the body, sometimes in opposite directions and sometimes in generally the same direction.

We make a wide range of pump sizes to cover a wide range of pressure heads and flow rates. Over forty different impeller shapes for example are currently available and over thirty different pump bodies to accommodate these impellers. Generally the pumps run at a moderate speed, typically 1 500 rpm although they can run at much higher speeds.

It is an object of the present invention to simplify the construction of a flexible impeller pump.

According to the present invention there is provided a method of making a pump so that it can have either a high-pressure-low-flow first characteristic or a high-flow-low-pressure second characteristic, the pump comprising a flexible impeller housed in a generally circular pump chamber which has a cam and is closed by opposed sidewalls, characterised in that: the same impeller 1 6 is used for both characteristics; that for the first characteristic the chamber has a single cam 5A, a single inlet port PA in one sidewall 2B and a single outlet port PB in the opposite sidewall 2; that for the second characteristic the chamber has two cams SA, 5B, two inlet ports PA in one sidewall 2B and two outlet ports PB in the opposite sidewall 2.

According to another aspect of the invention there is provided a flexible impeller pump comprising a pumping chamber, having a diameter to width ratio of three or more, a flexible impeller mounted for rotation in the chamber and having a plurality of radially extending flexible vanes, a manifold having a connection port and means for connecting the port to a supply pipe and a plate-like member separating the manifold from the pumping chamber and having a liquid transfer port for transferring liquid between the pumping chamber and the manifold.

In one example the ratio of diameter to width is about 4.5.

Conveniently the pump can have a first and second manifold at inlet and outlet regions of the pump separated from the or each pumping chamber by a respective plate-like member with a liquid transfer port for transferring liquid between the pumping chamber and the associated manifold.

In order to provide a pump with a high volume output, the pumping chamber can comprise two cams diametrically opposed in the single pumping chamber, the or each plate having two liquid transfer ports for transferring liquid between the associated manifold and the pumping chamber, so that the pumping chamber has two inlets diametrically opposed and two outlets also diametrically opposed.

Preferably the or each manifold is formed from sheet metal.

According to yet another aspect of the invention there is provided a flexible impeller pump comprising a pump housing containing at least one pumping chamber; a flexible impeller mounted for rotation in the pump housing and having a plurality of radially extending flexible vanes; an inlet manifold having a hollow interior, a connection port and means for connecting the port to a supply pipe; an outlet manifold having a hollow interior, a connection port and means for connecting the port to an outlet pipe; an inlet plate, between the inlet manifold and the pump housing and defining at least one inlet port to the pump housing and a sidewall of a pumping chamber; and an outlet plate between the outlet manifold and the pump housing and defining at least one outlet port from the pump housing and a sidewall of a pumping chamber.

Preferably the pump housing has a cylindrical outer surface, a peripheral groove in the outer surface, and a flexible seal, such as an O-ring seal, located in the groove and sealing the outer surface to one of the inlet, or outlet, or intermediate manifolds. With the modular construction envisaged, there can be an intermediate manifold between two separate pumping chambers which connect the or each outlet of one chamber to the or each inlet of the next chamber.

In order that the invention can be clearly understood reference will now be made to the accompanying drawings in which: Fig. 1 is an axial cross-section through a flexible impeller pump according to a first embodiment of the invention and Fig. 2 and Fig. 2a show a perspective view of a flexible impeller pump according to a second embodiment of the invention, partly cut away, and with an exploded view of part of the pump.

Referring to Fig. 1 the pump has an outlet manifold 1 comprising a threaded spigot 1 A welded to a pressed metal cover portion 1 B. In this embodiment the metal would be stainless steel. The threaded spigot 1 A affords connection to an outlet pipe.

The manifold is sealed to a pump body 5, also made of stainless steel and having two diametrically opposed cams 5A and 5B and defines within it a substantially circular pumping chamber housing a flexible impeller 1 6 with radially extending flexible vanes. The impeller could for example be made of neoprene.

The sidewalls of the pumping chamber are provided by two wear plates 2A and 2B which are identical to their construction. As shown in Fig.

1 A each wear plate has a pair of diametrically opposed discharge ports PA and PB, respectively.

The location of these ports in relation to the cams 5A and 5B can be clearly seen in Fig. 1 A.

The outer periphery of the pump body 5 is circular and has a pair of peripheral grooves 3A and 3B housing O-ring seals such as 3. These seals seal the outer periphery of the pump body to the overlying annular rims of the outlet manifold 1 and inlet manifold 14.

The inlet manifold 14 is made of pressed metal, in this embodiment stainless steel, and is welded to a stainless steel threaded spigot 1 4A for connecting the inlet port to a supply pipe (not shown). The manifold 14 also provides a seal housing 1 4B housing a seal assembly 1 5.

Secured against the manifold 14 is a bearing housing 8 carrying two rolling contact bearings 9 and 9A and a second seal assembly 6. An O-ring 12 on shaft 7 slings away any liquid via discharge port 8A in the bearing housing.

The shaft 7 is carried in the bearings 9 and 9A and supports the flexible impeller 1 6 by means of co-operating splines on the shaft and grooves of the impeller hub 1 6A.

The inlet and outlet manifolds have equiangularly spaced lugs radially projecting from the surfaces of the manifolds and accommodating in holes therein, screw-threaded members for clamping the two manifolds towards each other and thus holding the pump body 5 between them.

See Fig. 2 for details.

Further lugs on the inlet manifold 14 and the bearing housing 8 are provided and have screwthreaded members for screwing the bearing housing to the inlet manifold, as shown in Fig. 2.

As an alternative to screw-threaded members and associated lugs, it is envisaged that quick release clamps of the toggle type, having an overcentre action, could be provided to enable a quickrelease arrangement so that either manifold can be released from the pump housing and, likewise, the bearing housing can be removed from the inner manifold quickly.

The bearing housing has a seal 10 for sealing the bearing 9. Between the seal 10 and the bearing 9 is a retaining ring 11 for retaining the bearing 9 in position.

In the embodiment described it is envisaged that the pump body 5 will have the cams 5A and 5B integrally formed therewith but it is not impossible that the body 5 could be completely circular both inside and out, with the associated cams 5A and 5B as separate parts screwed or otherwise fixed to the inside periphery of the pump body. In this way cams of different size could be fitted to adjust the pump through flow accordingly.

The impeller shown in the embodiment of Fig. 1 has a diameter to width ratio of about 4.5, corresponding substantially to the diameter to width ratio of the pumping chamber defined by the body 5 and the wear plates 2 and 2A. The minimum value for this ratio is 3.

It is a particular advantage that the pump is made in a modular way and, as will be seen from the next embodiment, many common parts can be used to provide two pumps of significantly different characteristics. The pump described in Fig. 1 would have a relatively high throughput and would be designed to operate at a speed of between 1000 and 1 500 rpm., at a modest pressure head. This pump has effectively a twostage pumping chamber with the two stages working in parallel so that the impeller, assuming clockwise rotation as viewed in Fig. 1 A draws liquid in from manifold 14 through port PB and pumps the liquid out through ports PA into outlet manifold 1.

As an alternative the pump of Fig. 1 could have a single cam only, say 5A, and a single inlet port PA and a single outlet port PB, using of course the same impeller 16. This pump would have a highpressure-low-flow rate characteristic.

Referring now to Fig. 2 parts of the pump of Fig.

2 which are identical to the corresponding parts of the pump of Fig. 1, have the same reference numerals. Thus the inlet manifold 1, outlet manifold 14, seal assembly 6, impeller 16 and bearing housing 8 are the same.

The pump comprises two axially-separated pumping chambers in respective pump bodies 23 and 24. Between the pump body 23 and 24 is an intermediate manifold formed by manifold body 25. The sidewalls of the pumping chambers of pump bodies 23 and 24 are formed by respective wear plates 22A and 22B. These wear plates are identical except that they have a different angular orientation with respect to the cam 23A of pump body 23 nd the cam 24A of pump body 24. The specific orientation to ensure that the outlet port 22B of wear plate 22A is correct in relation to the cam 23A achieved by a pin 26 secured in the side of pump body 23, which locates in a small hole 27 in wear plate 22A. A similar arrangement of pins and holes ensures that the orientation of the other wear plates with respect to the cams, is correct.

Furthermore the series of pins and holes ensures correct orientation of the relative parts of the pumps throughout the axial length so that not only are the wear plates and associated pump bodies in the correct orientation but also the cam 24A of pump body 24 is in the correct orientation with respect to the cam 23A of pump body 23, i.e.

diametrically opposed.

The intermediate manifold sidewalls are formed by wear plates 22B and 22A associated with the manifold body 25. An internal annular shoulder 25A defines the spacing between the associated wear plates.

The intermediate manifold is sealed to the adjacent pump bodies 23 and 24 in the same way as the inlet and outlet manifold 1 and 14 are sealed to the pump bodies. That is to say the seal is provided by an "O"-ring in peripheral grooves in the pump bodies 23 and 24 which seal underneath the projecting rims of the manifold body 25.

The inlet and outlet manifolds are clamped together by means of flanges 31 and 32, formed as part of the pressings to make the manifolds 1 and 14. A tie rod 33 with associated nuts 34 and 35 draw the manifolds together. Two further flanges (not shown) equally spaced around the circumference of the inlet and outlet manifolds are also provided with corresponding tie bolts in order to effectively clamp together the inlet and outlet manifolds and thereby hold the pump bodies, wear plates and intermediate manifolds between them.

Similarly the inlet manifold has three further flanges equally spaced circumferentially around it, as does the bearing housing 8, and one pair of opposed flanges 36 and 37 is shown in Fig. 2.

Similarly a tie rod and associated nuts are used in order to draw the inlet manifold and bearing housing together.

As can be seen with the embodiments of Figs.

1 and 2, a modular pump construction has been provided which enables any one of a number of different pumps to be constructed from a common set of parts. In particular the manifold can be easily exchanged for others which differ only in, for example, the size and/or type of male-threaded end for connection to supply pipes and outlet pipes. Thus for example it would be possible for a distributor to hold in stock alternative inlet and outlet manifolds so that if a customer required a particular connection thread which may not be the one on the pump in stock, then the distributor can easily dismantle the inlet and outlet manifolds from the pump in stock and replace them by inlet and outlet manifolds having the required connection threads.This is done simply by undoing the three tie bolts which hold the inlet and outlet manifolds together, and by undoing the tie bolts which secure the bearing housing to the inlet manifold. As mentioned with the previous embodiment, as an alternative to the tie rods and nuts, it would be possible to have quick release latch-type (toggle) devices with an overcentre action making the release of the various parts of the pump even quicker and easier still.

The only difference between the embodiment of Fig. 1 and the embodiment of Fig. 2, lies in the extra transfer port in the wear plates of Fig. 1, together with the pump body having an additional cam. The pump of Fig. 2, in constrast to the pump of Fig. 1 , would provide a much higher output pressure although the throughput would be lower than the pump of Fig. 1, once again at a designed rotational speed of somewhere between 1000 and 1500 rpm.

Then again it would be possible to construct a pump which had a second double-cam stage in series with the stage shown in Fig. 1, that is to say it could be constructed like the pump of Fig. 2 except that each pump body had a second cam and the wear plates had two transfer ports. This would provide a pump having the same throughput as the pump of Fig. 1, but at approximately twice the pressure head. But the pressure head would not be so high as the pump shown in Fig. 2.

In the embodiment of Fig. 2 and Fig. 2A it would be possible to omit the intermediate manifold 25 and one of the wear plates 22B or 22A, and use the transfer port of the other wear plate as both a discharge port for body 24 and inlet port for body 23, the bodies 24 and 23 being suitably oriented.

Furthermore the embodiment of Figs. 2 and 2A could use the double-cam arrangement shown in Fig. 1 in which case each body would have a second cam and each wear plate would have two transfer ports.

Claims (15)

1. A method of making a pump so that it can have either a high-pressure-low-flow first characteristic or a high-flow-low-pressure second characteristic, the pump comprising a flexible impeller housed in a generally circular pump chamber which has a cam and is closed by opposed sidewalls, characterised in that: the same impeller 1 6 is used for both characteristics; that for the first characteristic the chamber has a single cam 5A, a single inlet port PA in one sidewall 2B and a single outlet port PB in the opposite sidewall 2; that for the second characteristic the chamber has two cams 5A, 5B, two inlet ports PA in one sidewall 2B and two outlet ports PB in the opposite sidewall 2.

2. A flexible impeller pump comprising a pumping chamber, having a diameter to width ratio of three or more, a flexible impeller mounted for rotation in the chamber and having a plurality of radially extending flexible vanes, a manifold having a connection port and means for connecting the port to a supply pipe and a platelike member separating the manifold from the pumping chamber and having a liquid transfer port for transferring liquid between the pumping chamber and the manifold.

3. A pump as claimed in claim 2, wherein the ratio is about four and a half.

4. A pump as claimed in claim 2 or claim 3, comprising a second manifold and a second platelike member separating the second manifold from the side of the pumping chamber opposite the first-mentioned plate-like member.

5. A pump as claimed in any of claims 2 to 4 comprising a bearing housing carrying a shaft to drive the impeller, the bearing housing being secured against the side of one of the manifolds opposite the associated plate-like member.

6. A pump as claimed in any of claims 2 to 5, wherein the pumping chamber comprises a pump body clamped against the or each plate-like member and sealed to a peripheral rim of the or each manifold.

7. A pump as claimed in any of claims 2 to 6 comprising two cams at diametrically opposed locations in the pumping chamber, the or each plate having two liquid transfer ports for transferring liquid between the associated manifold and the pumping chamber.

8. A pump as claimed in any of claims 2 to 7, wherein the or each manifold is formed from sheet metal.

9. A pump as claimed in claim 6 as appended to claim 4 comprising at least two screw threaded members disposed radially outwardly of the pump body and serving to draw the manifolds toward each other.

10. A flexible impeller pump comprising a pump housing containing at least one pumping chamber; a flexible impeller mounted for rotation in the pump housing and having a plurality of radially extending flexible vanes; an inlet manifold having a hollow interior, a connection port and means for connecting the port to a supply pipe; an outlet manifold having a hollow interior, a connection port and means for connecting the port to an outlet pipe; an inlet plate, between the inlet manifold and the pump housing and defining at least one inlet port to the pump housing and a sidewall of a pumping chamber; and an outlet plate between the outlet manifold and the pump housing and defining at least one outlet port from the pump housing and a sidewall of a pumping chamber.

11. A pump as claimed in claim 10, wherein the pump housing comprises two pumping chambers axially separated, and an intermediate manifold connecting the outlet of one chamber to the inlet of the other.

12. A pump as claimed in claim 10, wherein the pump housing comprises two pumping chambers, and a wear plate between the pumping chambers and forming a common sidewall for both chambers and having a liquid transfer port acting as an outlet port for one chamber and an inlet port for the other chamber.

13. A pump as claimed in claim 10, claim 11 or claim 12 wherein the pump housing has a cylindrical outer surface, a peripheral groove in the outer surface, and a flexible seal located in the groove and sealing the outer surface to one of the inlet, or outlet or intermediate manifolds.

14. A pump as claimed in any of claims 10 to 13, wherein the pump housing includes a pump body clamped between manifolds on opposite sides thereof and having two cams at diametrically opposed locations, the inlet plate having two inlet ports and the outlet plate having two outlet ports.

15. A pump substantially as hereinbefore described with reference to the accompanying drawings.