PUMP WITH A FLEXIBLE IMPELER

Abstract: A pump has flexible vanes arranged in a helical path in the clearance between the stator and the rotor. In one form the pump is a rotor in a stator, helically wound vanes being present on the rotor, the inner surface of the stator including at least one can surface to flex the vanes.

Description: PUMP WITH A FLEXIBLE IMPELER The invention relates to a pump capable of a range of industrial uses. The pump is of particular value in the pumping of nutrient liquid to feed a culture of micro-organisms and so will be described in relation to that use, but by way of illustration only. The pump can however be used on other applications, e.g. in medical equipment. A pump can comprise a generally cylindrical stator containing an elongate rotor. The invention is based on the realisation that such a pump can be improved if flexible vanes are present in the clearance between the rotor and the stator. According to the invention in one aspect there is provided a pump comprising a stator having a generally cylindrical bore which contains a rotor, one of the stator and the rotor containing radially spaced apart vanes and the other of the stator and rotor having at least one radial deformation, the vanes being flexible and extending in a generally helical manner from one end of the shaft or the rotor towards the other and the deformation being disposed and arranged to flex the vanes when they meet the deformation. According to the invention in a specific aspect there is provided a pump comprising an elongate stator generally cylindrical in shape and containing an elongate rotor, the rotor having radially spaced apart flexible vanes secured to the surface of the rotor and extending in a generally helical manner from one end of the rotor towards the other, the vanes being in contact with the inner wall of the stator which includes at least one deformation arranged to flex the vanes as each passes the deformation. I have also described and claimed a method of using the pump. It is possible to reverse the location of the co-operating vanes and cam deformation surfaces within the pump. In another specific aspect therefore the invention provides a pump comprising a stator generally cylindrical in shape and containing a rotor, the inside surface of the stator having radially spaced flexible vanes which extend in a generally helical manner from one end of the stator towards the other, the vanes being in contact with the surface of the rotor which includes at least one deformation arranged to flex the vanes as they are passed by the deformation. The number of deformations may be varied. If a number of such surfaces is substantially evenly distributed about the major axis of the stator the rotor will be centred. The vanes may be made of any suitable natural synthetic material, typically a plastics, including where appropriate a biopolymer. They make take any suitable shape and preferably comprising a thin vertical web having an enlarged head. The design of the vanes will be related to the deformation surface(s) which act as a cam to flex the vanes as they go past the deformation. The pump may be connected to or be incorporated in a prime mover, for example, an electromagnetic drive system. The pump may be used for liquids or gases and may, for example, be used in association with a gas compressor. In another aspect the invention provides a method of pumping a fluid by rotation of a rotor in the generally cylindrical bore of a stator, one of the stator and the rotor carrying radially spaced apart flexible vanes and the other of the stator and the rotor at least one radial vane deflecting means, the vanes extending in a generally helical manner from one end of the stator towards the other, the method comprising rotating the rotor in the stator and flexing the vanes as they move past the vane deflecting means, whereby fluid between neighbouring vanes is caused to move along the rotor helically in addition to circumferentially. In a specific aspect the invention provides a method of pumping a fluid by means of a rotor in a stator, the rotor having radially spaced apart flexible vanes extending in helical manner along the rotor, the method comprising rotating the rotor in the stator and flexing the vanes as they move past at least one deformation in the wall of the stator, whereby fluid present between neighbouring vanes is caused to move along the rotor helically in addition to circumferentially. In another aspect the invention provides a method of pumping a fluid by rotation of a rotor in the generally cylindrical bore of the stator, one of the stator and the rotor carrying radially spaced apart flexible vans and the other of the stator and the rotor at least one radial deformation, the vanes extending in a generally helical manner from one end of the stator towards the other, the method comprising rotating the rotor in the stator and flexing the vanes as they move past one deformation, whereby fluid between neighbouring vanes is caused to move along the rotor helically in addition to circumferentially. A pump of the invention may be used to transport liquids such as blood or stiff slurries, e.g. cement based slurries, or in a multistage bore pump in, e.g. oil wells. If any solid particles become trapped between the vanes and the inner surface of the stator the vanes will flex so allowing the pump to continue operating, especially when a number of cam surfaces is present. Other features of the invention are set out in the dependent claims. In order that the invention may be well understood it will be described by way of example with reference to the accompanying diagrammatic drawings, in which: Figure 1 is an end elevation of one pump of the invention; Figure 2 is a perspective view from one end of the rotor; Figure 3 is a front elevation showing the flow of liquid; Figure 4 is a side elevation of a second pump of the invention; Figure 5 is a sectional view taken on lines V - V on Figure 4; and Figure 6 is a sectional view of a third pump of the invention. The same reference numerals are used to describe the different embodiments where convenient. The pump comprises an elongate stator 1 formed of generally rigid material such as metal or plastics or ceramic or the like. The stator has a generally circular bore 2 having a chordal deformation to act as a cam surface 3. This may be an infill or machined in place. The stator 1 contains a rotor 4 having an elongate shaft 5 made of say stainless steel. The shaft is connected to a prime mover, not shown. A sleeve 6 is secured to the shaft and is made say of plastics or rubber. Vanes 7 are present on the sleeve, each comprising a radial web extension 8 and ending in a bulbous head 9. The vanes 7 are secured in parallel and extend along a helical path which travels along the sleeve length. If one cam surface 3 is present as shown the path will travel 360° but if more than one cam surface is present the travel will be less, e.g. for 4 cams the travel can be 90°. The vanes 7 are dimensioned such that when the vanes are at rest remote from the cam 3 the shaft is self centred. It will be noted that although the pump is devoid of bearings or seals, it is self centring. In use, the rotor 4 is placed in the stator 1 in a liquid flow path and the pump is energised by means, not shown. As a shaft rotates the vanes 7 reach the cam face 3 where they are compressed (see Figure 1) giving the liquid flow an extra kick. Because the vanes 7 are on a helical path the liquid flows helically which is advantageous. In the embodiment of Figures 4 and 5 the pump comprises a shell 10 (acting as the stator) and having a side inlet 11 and an inline outlet 12. The rotor 12 is a closed body having cone shaped ends 13, 14 shaped to correspond to the facing surfaces of the inlet and outlet walls 15, 16 respectively. Vanes 7 mounted on or integral with sleeve 6 are present on the rotor body. The inside of the stator has three deformation or cam surfaces 3A, 3B, 3C substantially evenly spread about the inner surface of the stator. An electromagnetic coil 20 is mounted on the outside of the stator and a set of magnets 22 is mounted inside the rotor body 12. The magnets 20, 21 co-operate in known manner when energised from a power source to drive the pump which works as described in relation to the embodiment of Figure 1 to 3. In use the cams 3A, 3B, 3C by flexing vanes 7 at any one time will tend to centre the rotor. If the pump fails in any way, the fluid under the higher pressure will force the rotor to move to seal the inlet or outlet by engagement of the surfaces 13, 15 or 14, 16. In the embodiment of Figure 6, the vanes 7 are mounted on the inner surface of the bore 2 of the stator 1 and three cams 3 are spaced about the circumference of the rotor 4. Electromagnets 20, 21 are present, as in the embodiment of Figures 4 and 5. The diameter of the bore in this embodiment may be relatively larger than in the earlier ones. The apparatus works in the same way as the previous embodiments and pumped fluid is caused to flow both circumferentially and helically of the rotor. The invention is not limited to the embodiment shown. The number of vanes may be varied but two or more are usually required to prevent back flow. The stator may be made of a rigid or semi-rigid material; more than one cam surface may be present. More than one pump of the invention may be present in a system, either in parallel or in series. The fluid pumped may be liquid or gaseous liquid. The pump may be made of lightweight materials. The length of the stator and rotor will depend on the use to which the pump is to be put.

Claims: CLAIMS 1. A pump comprising a stator having a generally cylindrical bore which contains a rotor, one of the stator and the rotor carrying radially spaced apart vanes and the other of the stator and rotor having at least one radial deformation, the vanes being flexible and extending in a generally helical manner from one end of the shaft or rotor towards the other and the deformation being disposed and arranged to flex the vanes when they meet the deformation. 2. A pump according to Claim 1, comprising an elongate stator generally cylindrical in shape and containing an elongate rotor, the rotor having radially spaced apart flexible vanes secured to the surface of the rotor and extending in a generally helical manner from one end of the rotor towards the other, the vanes being in contact with the inner wall of the stator which includes at least one deformation arranged to flex the vanes as each passes the deformation. 3. A pump according to Claim 1, comprising a stator generally cylindrical in shape and containing a rotor, the inside surface of the stator having radially spaced flexible vanes which extend in a generally helical manner from one end of the stator towards the other, the vanes being in contact with the surface of the rotor which includes at least one deformation arranged to flex the vanes as they move past the deformation. 4. A pump according to any preceding Claim, wherein the vanes travel a path at least 360° about the stator inner surface or the shaft when one deformation is present. 5. A pump according to any of the Claims 1 to 3, including deformations substantially evenly spread about the axis of the stator. 6. A pump according to any preceding Claim, wherein the pump is devoid of bearings or seals. 7. A pump according to any preceding Claim, including drive electromagnets . 8. A method of pumping a fluid by rotation of a rotor in the generally cylindrical bore of the stator, one of the stator and the rotor carrying radially spaced apart flexible vanes and the other of the stator and the rotor at least one radial deformation, the vanes extending in a generally helical manner from one end of the stator towards the other, the method comprising rotating the rotor in the stator and flexing the vanes as they move past one deformation, whereby fluid between neighbouring vanes is caused to move along the rotor helically in addition to circumferentially. 9. A method of pumping a fluid according to Claim 8, the rotor having radially spaced apart flexible vanes extending in helical manner along the rotor, the method comprising rotating the rotor within the stator and flexing vanes as they move past at least one deformation in the wall of the stator, whereby fluid present between neighbouring vanes is caused to move along the rotor helically in addition to circumferentially. 10. A method of pumping a fluid according to Claim 8, the inside surface of the stator having radially spaced flexible vanes which extend in a generally helical manner from one end of the stator towards the other, the vanes being in contact with the surface of the rotor which includes at least one deformation, the method comprising rotating the rotor within the stator and flexing the vanes as they move past the one deformation, whereby fluid present between neighbouring vanes is caused to move along the rotor helically in addition to circumferentially. 11. A method according to Claim 8, 9 or 10, wherein the fluid is a liquid such as blood. 12. A method according to Claim 8, 9 or 10, wherein the fluid is a slurry.

Inventors: SKILL STEPHEN, SKILL, STEPHEN
Applicants: SKILL STEPHEN, SKILL, STEPHEN
Application year: 1999
Main classification: F04C5
IPC codes: F04C5