EP0200510A2

EP0200510A2 - Improvements in or relating to pumps

Info

Publication number: EP0200510A2
Application number: EP86303182A
Authority: EP
Inventors: Raymond C/O Fgl Projects Limited Gannon
Original assignee: FGL Projects Ltd
Current assignee: FGL Projects Ltd
Priority date: 1985-05-01
Filing date: 1986-04-28
Publication date: 1986-11-05
Also published as: GB8511097D0; EP0200510A3

Abstract

A pump comprising a deformable tube which passes through an external casing divided into air-tight chambers each connected to a source of increased and reduced pressure. The tube contains a valve means so that when different parts of the tube are subjected to a predetermined sequence of variations in pressure by varying the pressure in the chambers fluid within the tube is urged from its inlet to its outlet.

Description

This invention relates to a pump and more particularly to a pump that operates by peristaltic action.
Pumping of fluids is ofen a very specialised operation necessitating frequently the use of pumps the design of which is influenced in large measure by the nature of the fluids to be moved. Those components of the pump which are likely to make contact with the fluids must be inert to them and when, for example, the fluids are corrosive pumps which can handle such materials are generally very expensive. The pumping of liquids which are required to retain a high degree of sterility or contain lumps of solid matter also pose considerable problems in pump design. A further problem is that pumps are often relatively bulky and there are occasions when they cannot be placed where they are most needed. In such cases the pump may have to be situated in a less convenient location in which case liquid to be moved has to be piped to and from the pump and this can introduce other difficulties. The present invention is directed to a pump which not only reduces the disadvantages of many existing pumps but in addition provides other important advantages.
Accordingly this invention provides a pump comprising a tube having an inlet and an outlet and made at least partly of readily deformable material means for deforming the tube by application of increased or reduced pressure to a selected part of the external surface of the tube, the pressure being applied by a fluid, and valve means within the tube so that when the selected part is subjected to a predetermined sequence of variations in pressure fluid within the tube is urged from the inlet to the outlet.
As a further embodiment of this invention there is provided a pump comprising: at least one chamber; means for alternately connecting the or each chamber to sources of increased and reduced pressure; a tube passing from the exterior through the chamber or chambers and having a reduced thickness wall portion within the or each chamber; and non-return valve means within the or each said wall portion at each end thereof, the arrangement being such that, in operation, when the or each wall portion of the tube is connected to the source of reduced pressure, fluid is drawn thereinto from a preceding portion of the tube and when connected to the source of increased pressure fluid flows therefrom to a succeeding portion of the tube.

Figure 1 is a cross-section of a pump according to the present invention; and
Figure 2 is a schematic perspective view illustrating the operation of the pump of Figure 1.
Figures 3 and 4 show an alternative form of invention pump in different stages of its operation.

Referring to the drawings 1 and 2 there is shown one embodiment of a pump according to the present invention. The pump has an exterior rigid housing 10 which is divided into two chambers 11, 12 by an internal wall 13. Each end wall 14 of the housing 10 has an aperture 15 therein and the wall 13 has an aperture 16 therein, the apertures 15, 16 being aligned to allow a soft and pliable tube 17, for example, of silicone or latex rubber, to pass through the chambers 11, 12. Seals 18 are provided between the apertures 15, 1 6 and the tube 17. Each of the chambers 11, 12 has an outlet 19.
Within the tube 17 are three non-return valves 20, 21, 22 (shown schematically) all operating in the same direction. The valves 20, 22 are located in the vicinity of the apertures 15 in the end walls 14 of the housing 10, and the valve 21 is located in the vicinity of the aperture 16 in the wall 13.
The tube 17 has reduced thickness wall portions 23 located substantially centrally within the chambers 11, 12. The valves 20, 21- are thus substantially at the ends of the reduced thickness wall portion 23 of the tube 17 in the chamber 11 and the valves 21, 22 are substantially at the ends of the reduced thickness wall portion 23 of the tube 17 in the chamber 12.
The operation of the pump will be described with reference to Figure 2. By alternately connecting each of the chambers 11, 12 to sources (not shown)of increased and reduced pressure via the outlets 19, a flow of fluid, that is gas or liquid, can be-induced within the tube 17. More particularly, when the chamber 11 is connected to the source of reduced pressure the reduced thickness wall portion 23 of the tube 17 located in the chamber 11 will expand. This causes the valve 21 to close and the valve 20 to open allowing fluid to enter the reduced thickness wall portion 23 of the tube 17 within the chamber 11 from the preceding portion of the tube outside the housing 10. Whilst the chamber 11 is connected to the source of reduced pressure, the chamber 12 is connected to the source of increased pressure which reinforces the closing action of the valve 21.
When the chamber 11 is connected to the source of increased pressure, the tube 17 will tend to collapse so that the valve 20 will close and the valve 21 will open so that some of the fluid in the reduced thickness wall portion 23 of the tube 17 within the chamber 11 will transfer to the succeeding reduced thickness wall portion of the tube within the chamber 12 which, at this time, is connected to the source of reduced pressure so that the reduced thickness wall portion 23 of the tube 17 in the chamber 12 is inflating drawing the fluid from the preceding reduced thickness wall portion of the tube 17 in the chamber 11. The valve 22 is closed due to the fact that the chamber 12 is connected to the source uf reduced pressure. When the chamber 12 is next connected to the source of increased pressure the valve 21 closes and the valve 22 opens so that some of the fluid in the reduced thickness wall portion of the tube 17 within the chamber 11 is forced from the pump to the succeeding portion of the tube.
The above described cycle may be operated at any desired speed and may use any desired degree of reduced or increased pressure to give a pulsed or continuous flow of fluid from the pump. Moreover, a pump according to the present invention can, if desired, have one or more than two chambers. The housing 10 may be cylindrical and have, for example, a maximum diameter between 300 mm and 5 mm.
The pump illustrated in Figures 3 and 4 comprises an exterior housing (1) which is divided into three chambers (2, 3 and 4) each of which is provided with a conduit (5, 6 and 7) communicating with a source (not shown) of increased and reduced pressure. Chambers (2, 3and 4) are separated from one another by air-tight walls (8 and 9) which form an air-tight seal by insertion into an annular groove (10 and 11) formed in a thickened part of wall (12) of a tube which extends through the housing (1). The tube is made preferably of a silicone rubber and the wall is sufficiently thin to permit it to be readily deformable. The wall at the ends of the tube is thickened and forms an air-tight seal (13 andl4) with end walls of chambers (2 and 4). The tube is provided with inlet (15) and outlet (16).
In order to operate the pump the following sequence of actions is carried out. Air under pressure is introduced into compartment (2) through conduit (5). As a result opposing parts of the wall of the deformable tube (12) are compressed together to form a seal (17 - Fig. 3). Conduits (6) are then connected to a source of vacuum and this causes the wall of the part of the tube (12) in chamber (3) to expand and to become filled with fluid which enters the pipe through inlet (15) and passes through that section of the pipe contained in chamber (4). When the section of the pipe in chamber (3) has expanded fully air under pressure is admitted into chamber (4) through a conduit (7) resulting in the wall of the tube being compressed together to form a seal (18 - Fig. 4) similar to that in chamber (2 - Fig. 3). The pressure in chamber (2 - Fig. 4) is then released and pressure created in chamber (3); as a result the fluid in that part of the pipe contained in chamber (3) is forced through the section of the pipe in chamber (2) and discharges from outlet (16). The cycle of operations is then repeated.
Figures 3 and 4 show that the only material with which fluid passing through the pumps illustrated makes contact is the material from which the pipe has been made. Since silicone rubbers are both very inert chemically and have the necessary degree of deformability their use in the present pumps is preferred. Nevertheless other natural or synthetic deformable particularly elastomeric materials can also be used provided that they have the necessary degree of inertness to the fluid being pumped.
One advantage of the present pumps is that they can be made from relatively inexpensive materials and their size can be made to vary over wide limits. Thus very small pumps can be made for medical and surgical uses for example the drainage of urine from a patient. Pumps for such purposes can be supplied sterile wrapped and thrown away after use thereby avoiding the need for resterilising. Tube (12) in he form of pump illustrated in Figures 3 and 4 when not in use is substantially free of any constriction although as shown above constrictions are formed in a controlled way when the wall of the tube is deformed by the externally applied pressure and then acts as a valve. Pumps of this construction are especially useful in the moving of fluids which contain lumps of solid ofsemi solid matter, for example, conserves of fruit such as jam or other foodstuffs. In such instances the width of tt e bore of the tube can be arranged to be too wide to by blocked by any lumps present in the fluid. Furthermore, even if a lump is present in a part of the tube where oppsing parts of the wall are being compressed together (17 and 18) to form a valve the effect of the lump is merely to assist in tie temporary blocking of the tube. When the opposing parts of the wall are subjected to a vacuum during the next stage of the pumping cycle they separate and the lump is released and transported away in the stream of fluid without interfering with the efficiency of the pumping operation.
These pumps can be operated by any conventional pressure and vacuum pump which is connected by suitable piping to the invention pumps. Since the latter can be made very small and compact they can therefore be used in situations which would be impossible for conventional pumps.

Claims

1. A pump comprising a tube having an inlet and an outlet and made at least partly of readily deformable material means for deforming the tube by application of increased or reduced pressure to a selected part of the external surface of the tube, the pressure being applied by a fluid, and valve means within the tube so that when the selected part of the external surface is subjected to a predetermined sequence of variations in pressure fluid within the tube is urged from the inlet to the outlet.

2. A pump according to Claim 1 comprising at least one chamber means for alternately connecting the or each chamber to sources of increased or reduced pressure, a tube passing from the exterior through the chamber or chambers and having a reduced thickness wall portion within the or each chamber, and a non-return valve means within the or each said wall portion at each end thereof, the arrangement being such that, in operation, when the or each wall of the tube is connected to the source of reduced pressure, fluid is drawn thereinto from the preceding portion and when connected to the source of increased pressure fluid flows therefrom to a succeeding portion of the tube.

3. A pump as claimed in either of Claims 1 or 2 wherein the tube is contained within a housing which is divided into a plurality of chambers.

4. A pump as claimed in any one of the preceding claims wherein the valve means comprises opposing parts of the tube which are capable of being urged together by pressure and which when urged together prevent the flow of fluid through the tube.

5. A pump according to any one of the preceding claims wherein the tube comprises a natural or synthetic elastomer.

6. A pump as claimed in Claim 5 wherein the synthetic . elastomer is a silicone.

7. A pump as claimed in any one of the preceding claims wherein the external surface of the tube is provided with an annular groove.

8. A pump as claimed in any of Claims 2, 3 and 7 wherein a wall of each chamber is recessed in the annular groove.

9. Pumps as hereinbefore claimed in any one of the preceding claims.

10. Pumps as hereinbefore described with particular reference to the drawings.