GB2226601A - Peristaltic pump - Google Patents

Abstract

Fluid carrying tubes 16 are located in a confined space at the point of roller pressure to limit the amount of uncontrolled deformation of the tubes 16 which can take place at that point. In one embodiment the pump has a housing 12 which defines a circular chamber (26, Fig. 2) which receives a rotatable roller head 14 carrying a plurality of rollers 20 spaced around the head. The walls 22 of the housing and each one of the rollers 20 define a respective 'nip' the cross-section of which confines and restricts the deformation of the tubes so that high effective pressure can be transmitted to the fluid in the tubes resulting in high fluid pressures and flow rates. <IMAGE>

Description

IMPROVED PERISTALTIC PUMP The present invention relates to an improved peristaltic pump and particularly, but not exclusively, to a peristaltic roller pump which can produce high fluid flow rates at relatively high pressures.

A peristaltic roller pump should satisfy a number of desirable criteria in addition to being sterilizable and easy to use. The pump should create high pressure and flow rates in the tubes without creating unnecessary friction or drag on the tubes which can result in heating of the tubes and fluid therein. The uncontrolled deformation of the tubes at the point of roller pressure should be minimised because this deformation limits the effect of the peristaltic pumping action. The pump should also be readily disrantled for maintenance and sterilization and should be usable with different sizes of tubes.

Existing peristaltic roller pumps have a number of disadvantages which do not fulfil one or more of the above mentioned criteria. In particular, unrestricted deformation of the tubes containing the liquid in a direction transverse to the direction of the roller pressure is considerable with existing peristaltic pups, This makes it difficult to maintain igh pressures and fluid flow rates which, in turn, limits the applications of the pump.

Also, existing pumps are not readily sterilizable and cannot readily be dismantled to receive tubing of different sizes.

An object of the present invention is to provide a peristaltic pump which obviates or mitigates at least one of the aforementioned disadvantages.

This is achieved by providing a device which locates the fluid carrying tubes of the peristaltic pump in a confined space at the point of roller pressure limiting the amount of uncontrolled deformation of the tubes which can take place at that point.

In one embodiment the device consists of a pump housing which defines a circular chamber which receives a rotatable roller head carrying a plurality of rollers spaced around the head. The walls of the housing and one of the rollers define a 'nip' the cross-section of which confines and restricts the deformation of the tubes so that high effective pressure can be transmitted to the fluids in the tubes resulting in high fluid pressures and flow rates.

In another embodiment the confined space is defined by a tube carrying sleeve which is disposed in the pump housing of similar shape to that of the previous housing.

However, the roller head is modified to engage the tube portions projecting froir the sleeve and, with the sleeve, define a nip which limits uncontrolled deformation of the tubes at the nip or point of roller pressure.

Accordingly, in one aspect of the present invention there is provided a peristaltic pump comprising a pump housing and a roller means for rotating about an axis within the pump, the pump and the roller means defining a cavity for receiving tubes carrying fluids to be pumped, the housing have a surface for locating fluid carrying tube, said roller means having at least one roller, said surface and said roller defining a 'nip', said nip being rotatable about the axis as roller means rotates to move the fluid through the tube, said surface and said roller means defining tube confining means for limiting the deformation of the tube at the 'nip' whereby, in use, as said roller means rotates fluid is moved through the tube at a relatively high press rue and flow rate.

Preferably, the roller means is cylindrical and has circular plates spaced apart by the or each roller, said roller being disposed inwardly from the edge of said plates to define lips which form the top and bottom of said tube confining means.

Alternatively, the surface defines a channel for receiving tubes and the roller. The top and bottom of the roller head is cylindrical with the roller being disposed at the edge so that the roller and channel define the tube confiring means.

Alternatively, the surface of the housing for receiving the tube is provided by a separate channel-shaped sleeve mounted within said housing.

Preferably also, the circular plates of the roller head are spaced apart by a plurality of rollers spaced around the periphery of the circular plates.

Conveniently, there are four rollers spaced at 900 intervals around the periphery of the circular plates.

Preferably also, the cross-section of the confining means defined at each 'nip' is rectangular.

These and other aspects of the invention will become apparent from the following description when taken in combination with the accompanying diagrams in which: Fig. is a diagrammatic view of an embodiment of a peristaltic pump, in use, in accordance with the present invert I on; FIg. 2is a perspective view of the housing for use with the pump shown in Fig. 1; Fig. 3 is a perspective view of the roller head shown in Fig. 1; Fig. 4 is a cross-sectional view taken along line 4-4 in F-g. 1 of an assembled pump; Fig. 5 is a perspective view of another embodiment of a put?, with housing piece and housing sleeve;; Fig. 6 is a cross-sectional view taken along line 6-6 of the assembled pump shown in Fig. 5, and Fig. 7 is a graph of flow rate vs pressure for a pump in accordance with the embodiment in Fig. 1 and for existing pumps.

Reference is first made to Fig. 1 which shows a high flow rate and high pressure sterilizable peristaltic pump generally indicated by reference numeral 10. The pump consists of a housing 12 and a pump roller head 14 for receiving tubes 16 as shown which carry fluid to be moved through the tubes by the pump as will be described.

Reference is now made to Fig. 2 which shows the housIng 12. The housing 12 comprises two curved walls 22 which. are coupled together by hinge 24 to be readily opene to receive roller head 14. The internal surfaces 25 of the curved wall 22 define a circular chamber 26 for receiving the roller head 14 as shown in Fig. 1. At the free end of each of the walls 22 two holes 27 form guides and supports for tubes 16.

preference is now made to Fig. 3 of the drawings which shows the roller head 14 in more detail. The roller head 14 ccnsists of two circular plates 18 separated by four cylindrical rollers 20 which are spaced at 900 intervals arour. the circumference of the plates 18. The cylindrical rollers 20 are disposed inwardly of the plate edges to define lips 21 for confining the tubes 16 between the ps as will be described.

Preference is now made to the cross-section shown in Fig. 4. This shows two of the confined spaces 28 of generally rectangular cross-section created at four 'nip' positions around the roller head 14. Each confined space 28 is defined by the lips 21 of the plates 18, the roller 20 and the internal surface 25 of the curved wall 22. At each nip, as shown in Fig. 4, the restricted deformation of the tubes 16 is achieved by the cross-sectional area of the confined space 28 thereat.

Each confined space 28 or 'nip' rotates around the circular chamber 26 as the roller head 14 rotates about the axis shown in Fig. 4. The space between each adjacent pair of nips defines a 'slug' of fluid'and as this 'nip' rotates, the 'slug' is forced round the circular chamber 26. Because deformation of tubes 16 is restricted at the np, > .igh flow and high pressure is achievable with the fluid being pumped.

Reference is now made to Fig. 5 which shows an alternative embodiment in which like numerals refer to like parts but with suffix 'a' added. The housing 12a comprises two curved walls 22a which are coupled together by hInge 24a to be readily opened and closed for receiving a hosing sleeve 30 and roller head 14a (Fig. 6).

he internal surfaces 25a of the curved walls 22a defire a cylindrical chamber 26a for receiving the housIng sleeve 30.

The housing sleeve 30 comprises two curved walls 32 connected at one end. At the free end of each curved wall 32 two holes 34a form a guide and support for tubes 16a.

The internal surface 36 of each curved wall 32 define a chamber 38 for confining, in part, the tubes 16 as will be described.

Reference is now made to the cross-section shown in Fig. 6. This shows two of the confined spaces 28a of generally rectangular cross-section created at each of the four positions around the roller 14a. These spaces 28a are defined by the housing sleeve 30 and the cylindrical rollers 20a. At each nip, shown in Fig. 6, controlled deformation of tubes 16a is achieved by the limiting cross-sectional area of the confined space 28a at the nip.

he confined space 28a or 'nip' rotates around the circar chamber 26a as the roller head 14a rotates. The 'slucs' are forced around the chamber 26a and high flow and pressure of the fluid being pumped is obtained.

FIg. 7 shows the flow rate pressure line (a) for the pump of Figs. 1 - 4. It will be appreciated that with this pump flow rates at 2 to 4 Bar are about four times those acheived with existing pumps.

Various modifications can be made to the embodiment hereinbefore described without departing from the scope of the invention. For example, the confined space or nip can be fined by any suitable combination of the housing or sleeve and the roller head. For example, the housing itself could form three walls of the confined space. Also any number of rollers can be used in the roller head to vary the number of nips.

Similarly, any number of tubes can be accommodated and distributed internally around the housing. Also the cross-section of the confined space at the 'nip' can be of any suitable shape to limit the deformation of the tubes.

Also the rollers can be moved relative to the housing to var the nip pressure, and to vary, in use, fluid pressure and flow rates.

Advantages of the embodiments are that the parts are simply manufactured and assembled, there is a minimal number of parts. In addition, the pump is readily sterilizable and can be used for high flow and high pressure applications. An advantage of the second erbc=Iment is that the pump sleeve can be readily replaced b seeves for accommodating different numbers of tubes.

Claims (9)

1. A peristaltic pump comprising a pump housing and a roller means for rotating about an axis within the pump, the pump and the roller means defining a cavity for receiving tubes carrying fluids to be pumped, the housing having a surface for locating at least one fluid carrying tube, said roller means having at least one roller, said surface and said roller defining a 'nip', said nip being rotatable about the axis as roller means rotates to move the fluid through the tube, said surface and said roller means defining tube confining means for limiting the deformation of the tube at the 'nip' whereby, in use, as said roller means rotates fluid is moved through the tube at a relatively high pressure and flow rate.

2. A peristaltic pump as claimed in claim 1 wherein the roller means is cylindrical and has circular plates spaced apart by the or each roller, said roller being disposed inwardly from the edge of said plates to define lips which form the top and bottom of said tube confining means.

3. A peristaltic pump as claimed in claim 1 wherein the surface defines a channel for receiving tubes and the top and bottom of the roller means are cylindrical plates with the or each roller being disposed at the edge of said plates so that the roller and channel define the tube confining means.

4. A peristaltic pump as claimed in any preceding claim wherein the surface of the housing for receiving the tube is provided by a separate sleeve mounted within said housing.

5. A peristaltic pump as claimed in claim 4 wherein said sleeve is channel shaped.

6. A peristaltic pump as claimed in claims 2 to 5 wherein the circular plates of the roller means are spaced apart by a plurality of rollers spaced around the periphery of the circular plates.

7. A peristaltic pump as claimed in claim 6 wherein there are four rollers spaced at 900 intervals around the periphery of the circular plates.

8. A peristaltic pump as claimed in any preceding claim wherein the cross-section of the confining means defined at each 'nip' is rectangular.

9. A peristaltic pump substantially as hereinbefore described with reference to Figs. 1 to 4 or Figs. 5 and 6 of the accompanying drawings.