GB2091344A

GB2091344A - Multi-stage pump

Info

Publication number: GB2091344A
Application number: GB8101615A
Authority: GB
Original assignee: ITT Fluid Handling Ltd
Current assignee: Xylem Jabsco Ltd
Priority date: 1981-01-20
Filing date: 1981-01-20
Publication date: 1982-07-28
Also published as: SE8200238L; ES508914A0; ES8305093A1; GB2091344B

Abstract

A multi-stage flexible-vane impeller pump has identical pumping chambers 101, 102, 103 between closure plates 104, 105, 106, 107. A single shaft 110 carries identical impellers 112, 113, 114. The inlet to the first chamber is via passageway 115 communicating with inlet port 116. Ports in plates 105, 106, 107 may be angularly displaced by 120 DEG or 180 DEG and the outlet from chamber 101 is the inlet to chamber 102, the outlet from chamber 102 being the inlet to chamber 103. Outlet port 118 from chamber 103 communicates with the pump outlet passage 117. In another construction (not shown) the inlets and outlets of the chambers are via radial fronts which communicate externally. <IMAGE>

Description

SPECIFICATION Multi-stage pump This invention relates to pumps of the type having impellers provided with elastomeric radial vanes which are flexed by cams in the otherwise cylindrical bores of the pumps in response to rotation of the impellers, to pump fluid from an inlet leading into an impeller bore on one side of the cam to an outlet from the bore on the other side of the cam.

Such pumps are known from British patents Nos. 812,437 and 813,223. The operation of a flexible vane pump is illustrated in Fig. 1 of the accompanying drawings. A flexible vane impeller 10 is keyed onto a shaft 11 and rotates within a generally cylindrical bore 12. Affixed within the bore 12 is a cam 13. The vanes 1 Oa of the impeller are in substantially unflexed engagement with the cylindrical periphery of the bore during rotation. However when the flexible vanes encounter the leading surface 1 3a of the cam 13 they are caused to flex, bending towards the hub of the impeller. Conversely when the flexed vanes reach the trailing surface 1 3b of the cam they resume their unflexed condition. Adjacent vanes define between them a volume 14.The bore is provided with inlet and outlet ports 15, 16, which may be radial or axial, adjacent the trailing and leading surfaces 1 3b, 13a respectively of the cam 13. As shown in Fig. 1 the ports 15, 16 are axial, that is they are openings in plates (not shown) which otherwise close the ends of the cylindrical bore 12. Thus when the vanes traverse the trailing surface of the cam the volume 14 defined by each pair of vanes expands as the vanes pass from the flexed condition, caused by the cam 13, to the unflexed condition. This increase in volume causes a reduction in fluid pressure as the volume passes the inlet part 15, causing the volume to fill with fluid from the inlet part. This fluid is then carried round until the volume reaches the leading surface of the cam.Here the vanes are flexed, the volume is compressed and the fluid is expelled through the outlet port 16.

According to the present invention there is provided a pump of the radial vane type comprising a housing, a rotatable shaft within the housing driving a plurality of radial vane impellers in respective pumping chambers positioned sideby-side along the shaft, the pump inlet communicating with the first of said chambers and the pump outlet communicating with the last of said chambers, the inlet of each succeeding chamber communicating with the outlet of the preceding chamber.

An embodiment of the invention will now be described with reference to Figs. 2-5 of the accompanying drawings, in which: Fig. 2 is a sectional illustration through a 3-stage pump, Fig. 3 illustrates a pump chamber, Fig. 4 illustrates a chamber closure plate, and Fig. 5 illustrates the relative orientation of the three stages of the pump of Fig. 2 viewed from the outlet end of the pump.

In Figs. 2-5 the same reference numerals are used for the same parts throughout.

The 3-stage pump has three identical pump chambers 101, 102, 103 closed by closure plates 104, 105, 106 and 107. Plate 107 differs from plates 104, 105 and 106 only in that it has no central hole. The alternating chambers and plates are clamped together in axial alignment between a pump inlet housing body 108 and pump outlet housing body 109 by means of studs 123 and nuts 124. The inlet housing body carries a rotatable shaft 110 mounted in a suitable sealed bearing arrangement 111. One end 111 a of the shaft protrudes outside the pump and receives a driving gear or pulley (not shown).The other end of the shaft 111 within the pump extends through the first two chambers and into the third and carries three identical flexible rubber vane impellers 112,113,114 which are keyed to the shaft. The inlet housing has a fluid inlet passage 11 5 which communicates via an axial inlet port 11 6 in plate 104 with the first chamber 101. The outlet housing 109 has a fluid outlet passage 11 7 which communicates via an axial outlet port 118 with the last chamber 103.

The two chambers 102 and 103 are successively angularly displaced by 1 200 with respect to the first chamber 101, as shown in Fig. 5. Likewise the plates 105-1 07 are successively angularly displaced by 1200. This in the first stage of the pump the outlet port 11 9 in plate 105 is angularly displaced by 1200 from the inlet port 11 6, with the cam 121 of the first chamber 101 therebetween. The outlet port 11 9, which is a simple hole in the plate 105, is also the inlet port for chamber 102. Port 120 of plate 106 is displaced by a further 1200 and is both the outlet from chamber 102 and the inlet to chamber 103. Finally plate 107 has its port 118 displaced by yet a further 1200 and is the outlet from chamber 103.All the joints between the plates and the chambers etc. are sealed against fluid pressure by means of O-rings located in annular grooves 122. The impellers are not shown in Fig. 5. Thus fluid is pumped successively through the three chambers in series, the total outlet pressure being three times the pressure available from a single chamber. Because the chambers, impellers, closure plates etc. are for the most part identical disassembly of the pump and its subsequent re-assembly are greatly facilitated.

Moreover, the chambers etc. are readily serviceable without the need for removing the pump housing body 108 or disconnecting the drive arrangement 111 a.

As an alternative form of construction each chamber can be machined or cast or moulded as a blind recess in a solid piece of metal, this obviating the need for separate closure plates between adjacent chambers. This reduces the number of joints requiring pressure-resistant sealing. The chambers (and closure plates) are readily fabricated in steel, stainless steel or other materials suitable for the fluids to be pumped.

Reference has been made to a three-stage pump as illustrated in the drawings. Other configurations, e.g. a 2-stage or a 4-stage pump, are possible. In a 2-stage pump, if a 1200 angular displacement is used, as in the 3-stage pump illustrated, then the inlet and outlet will angularly displace with respect to each other by 1200.

Similarly there will be a displacement of 1200 in a 4-stage pump. However, if the circumferential length of the vane-flexing cams is altered then the angular displacements can be changed. Thus it is possible to increase the cam lengths such that for a given chamber its inlet and outlet ports are displaced by 1800. Two such chambers in 2-stage pump would then provide a pump inlet and pump outlet radially aligned. Also, it may be necessary to choose the cam lengths such that there is a dynamic balance in a high speed multi-stage pump. Satisfactory dynamic balancing may obviate the need for an additional bearing for the otherwise free end of the driving shaft, as in the embodiment of the drawings.

In yet another form of construction, instead of adjacent chambers communicating directly with one another through a hole (port) in the intervening wall or plate the inlet to and outlet from each chamber may be by way of radial ports which are then communicated as required by external pipework or the like.

Claims

1. A pump of the radial vane type comprising a housing, a rotatable shaft within the housing driving a plurality of radial vane impellers in respective pumping chambers positioned side-byside along the shaft, the pump inlet communicating with the first of said chambers and the pump outlet communicating with the last of said chambers, the inlet of each succeeding chamber communicating with the outlet of the preceding chamber.

2. A pump according to claim 1 wherein a succeeding pumping chamber is separated from the next preceding pumping chamber by a closure member having a passageway which connects the outlet of the preceding chamber and the inlet to the succeeding chamber wholly within the radial dimensions of the adjacent pumping chambers.

2. A pump according to claim 1 wherein a succeeding chamber is separated from the next preceding chamber by a closure member having a single port which forms the outlet of the preceding chamber and the inlet to the succeeding chamber.

3. A pump according to claim 2, wherein each chamber comprises an annular body having a generally cylindrical bore with a vane flexing cam portion, the closure members being flat plates, the chambers and plates being assembled alternatively and clamped together to form the pump housing.

4. A multi-stage pump substantially as described with respect to the accompanying drawings.

New claims or amendments to claims filed on 18 Dec. 1981.

Superseded claims: Claim 2.

New or amended claims