GB2139710A - Pump - Google Patents

Abstract

A pump for liquids containing living cells or for carbonated beverages comprises a deformable connector 17 extending between an inlet (18) and an outlet, means for applying pressure to the exterior of the connector to deform it, and controlling means (19, 20) for causing liquid in the connector to exit through the outlet when pressure is applied to the connector and for causing liquid to be admitted into the connector through the inlet (18) upon relaxation of the pressure applied to the connector. The means for applying pressure comprise a magnetic liquid disposed in a sealed chamber (15), an electromagnet (16) being arranged to cause the magnetic liquid to deform the connector. <IMAGE>

Description

SPECIFICATION Pump This invention relates to a pump. If certain fluids such as those which contain living cells or which contain gas dissolved under pressure need to be transmitted then it is important that they are not subjected to mechanical stresses imposed thereon by conventional pis ton or rotary pumps which might damage the cells. For those purposes a peristaltic pump can be used. However, conventional peristaltic pumps are somewhat complicated by attempt ing to provide for a substantially constant flow of fluid therethrough.

According to the present invention there is provided a pump comprising an inlet and an outlet, a connector between said inlet and outlet, at least a part of said connector being deformable, means for applying pressure in termittently to the exterior of said connector to deform it, and controlling means for causing liquid in the connector to exit through the outlet when pressure is applied to the connec tor and for causing liquid to be admitted into the connector through the inlet upon relaxa tion of pressure applied to the connector.

According to the invention, therefore, the pump in its simplest form provides an inter mittent supply of fluid. It is, however, possible to provide for a more continuous flow by combining a plurality of pumps together and operating them sequentially.

The controlling means may comprise non return valves one disposed upstream of the outlet and another located downstream of the inlet. Another form of controlling means com prises a connector which responds in a non uniform manner to the application of pressure.

For example a connector may be provided which has a progressively increasing wall thickness between inlet and outlet. As pres sure is applied to the connector the connector progressively collapses in the direction to wards the outlet thereby causing liquid in the connector to flow from the outlet.

The means for applying pressure intermit tently to the exterior of the connector may comprise a liquid or other fluid which can be caused to exert pressure upon the connector.

Thus a liquid may be contained in a sealed chamber surrounding the exterior of the tube.

Pressure may be applied to the liquid, for example by means of a piston or diaphragm.

In alternative preferred embodiments of the invention the fluid comprises a magnetic liquid, that is a stable colloidal suspension of small particles of ferromagnetic material. The preparation and properties of magnetic liquids is discussed in a paper by S.W.Charles and J.

Popplewell (Endeavour, New Series 6, No.4, 153, 1982).

A pump in accordance with the preferred embodiment of this invention may comprise an electromagnet adapted to create a magnetic field in a portion of the chamber containing the magnetic liquid. Energisation of the magnet attracts the magnetic liquid causing compression of the connector and consequent expulsion of liquid to be pumped from within the connector.

Deformation of the connector serves to create a restoring force to decompress the connector when the magnet is de-energised.

A portion of the chamber containing magnetic liquid is preferably external to the magnetic field. Movement of magnetic liquid out of this portion causes deformation of the connector providing a further restoring force.

A pump in accordance with this invention may comprise two electromagnets arranged to create a magnetic field in different portions of the magnetic liquid contaning chamber. The magnets may be arranged to be actuated alternately, each utilising the compression of the connector caused by the other to contribute in the efficiency of the pumping action.

Pumps in accordance with this invention find particular application in delivery of liquids containing living cells, such as plasma, or in delivery of liquids containing dissolved gas, such as carbonated beverages.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a longitudinal section through a pump; Figure 2 is a diagrammatic transverse section through a plurality of pumps; Figure 3 is a cross sectional view of a second pump in accordance with this invention; and Figure 4 is an end elevation of the pump shown in Figure 3.

Referring to Figure 1 the pump comprises an inlet 2 and an outlet 4 joined by a tube 8 of flexible material such as plastics. Nonreturn valves 3 and 3' are located, one (3) downstream of the inlet and another (3') upstream of the outlet. The flexible tube 8 is enclosed by a rigid elongate housing 5 which is sealed at each end to the tube as at 7. A fluid 6 is disposed in the housing around the exterior of tube. The housing is adapted to receive means for applying pressure to the fluid 6, such means being for example a piston, diaphragm or the like and which is indicated by reference numeral 1.

In use the means 1 is actuated to apply pressure to the fluid 6 which in turn causes the tube to deform inwardly. Fluid within tube 8 is expressed through nonreturn valve 3' and outlet 4. Means 1 is then deactuated and the pressure applied to tube 8 thereby withdrawn.

Fresh fluid is drawn through the inlet 2 and non-return valve 3. The means 1 is actuated again and the above described cycle of operations repeated.

It will be clear from the foregoing that the pump described with reference to Figure 1 can only deliver fluid intermittently in a discontinuous manner. However, it is possible to combine a plurality of such pumps together to produce a substantially continuous flow.

As shown in Figure 2, three pumps 10, 12, 1 4 can be ganged together so that the inlets are coupled through a manifold to a single supply and the outlet coupled through another manifold to a single delivery means. By operating the three pumps sequentially a substantially continuous stream of fluid can be transmitted.

The invention is not confined to the above described embodiments and many variations can be made. For example the fluid 6 surrounding the tube 8 is chosen having regard to the fluid to be transmitted. Generally the fluid 6 will be a liquid such as water but it may if desired be a gas for example air.

In another modification the number of connectors in each housing may be increased so that a single pump can be used to deliver fluid from more than one source. In such an arrangement the relative quantities delivered from each source can be adjusted by selecting connectors of appropriate diameter and wall thickness. For example, if two connectors are used of the same diameter and compressibility then the amounts delivered through each connector by the pump will be substantially the same. If one connector is of smaller diameter and/or less compressible then that connector will deliver less than the other; in other words the pump functions at a proportioning device.

It will be appreciated that substantially continuous delivery can be obtained by combining the above modification with the ganged assembly of the kind described with reference to Figure 2.

The pump shown in Figures 3 and 4 generally resembles that shown in Figures 1 and 2 except that a magnetic liquid, such as a colloidal suspension of magnetite is contained in the sealed chamber 15, and pressure is exerted on the magnetic liquid by means of an electromagnet 16. The connector may be composed of silicone rubber or any other resilient material which is resistant to attack by the magnetic liquid.

A portion of the connector 22 defines a chamber 21 from which liquid to be pumped is driven by the compression of the connector.

The inlet and outlet from this chamber are defined by means of one-way valves 1 9 and 20 respectively.

The connector 1 7 extends beyond the chamber 21. The portion of the magnetic liquid retaining chamber 1 5 outside the electromagnet 1 6 serves as a reservoir from which the magnetic fluid is drawn as the magnet is energised. Passage of liquid from the chamber 1 5 causes deformation of the connector 1 7 and leads to a reduced pressure in the chamber 15, creating a restoring force to redistribute the magnetic liquid when the magnet is de-energised. The magnet may comprise a coil 23 and core 1 6 as shown in Figure 4. Any alternative arrangement may be adapted.

An alternative pump in accordance with this invention comprises two alternately energisable electromagnets disposed one adjacent the other about a single connector. Magnetic liquid is arranged to be drawn by each magnet alternately; When the first magnet is energised the restoring force of the evacuated portion of the connector assists the action of the second magnet when the latter is energised. Three one way valves are provided, being disposed between the magnets and at the inlet and outlet respectively.

Claims (11)

1. A pump comprising an inlet and an outlet, a connector between said inlet and outlet, at least part of said connector being deformable, means for applying pressure intermittently to the exterior of said connector to deform it, and controlling means for causing liquid in the connector to exit through the outlet when pressure is applied to the connector and for causing liquid to be admitted into the connector through the inlet upon relaxation of pressure applied to the connector.

2. A pump as claimed in claim 1, wherein the controlling means comprise non-return valves.

3. A pump as claimed in claim 1, wherein the controlling means comprises a connector which has a progressively increasing wall thickness between the inlet and outlet.

4. A pump as claimed in any preceding claim, wherein the said means for applying pressure comprises a fluid contained in a sealed chamber.

5. A pump as claimed in claim 4, wherein the means for applying pressure comprises a magnetic liquid contained in a sealed chamber.

6. A pump as claimed in claim 5, comprising an electromagnet adapted to create a magnetic field in a portion of the chamber containing the magnetic liquid.

7. A pump as claimed in claim 5 or 6, comprising two electromagnets adapted to create magnetic fields in different portions of the said chamber.

8. A pump substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

9. A pump substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.

10. A method of pumping a liquid containing living cells comprising use of a pump in accordance with any preceding claim.

11. A method of pumping a carbonated beverage comprising use of a pump in accor dance with any of claims 1 to 8.