GB2075128A

GB2075128A - A peristaltic pump

Info

Publication number: GB2075128A
Application number: GB8112393A
Authority: GB
Original assignee: LKB Produkter AB
Current assignee: Pfizer Health AB
Priority date: 1980-04-28
Filing date: 1981-04-21
Publication date: 1981-11-11
Also published as: FR2481375A1; DE3116862A1; JPS57391A

Abstract

The pump has a two-part stator 1, 2 encircling a rotor comprising rollers 3 that compress a pumping tube 10 against one of the stator parts and are separated by spacing pieces 4 fixed to a ring 5 whereon the rollers are mounted rotatively with freedom to move radially. The rollers are both rotated and pressed against the tube by a resilient ring 6 coupled to a drive shaft 9 by resilient arms 7. <IMAGE>

Description

SPECIFICATION A peristaltic pump Peristaltic pumps, i.e. pumps in which the medium to be pumped is contained in an elastic tubing and the pumping effect is provided by deforming the tubing and moving the deformation or deformations along the tubing, are commonly used especially in laboratory applications. The advantage of these pumps is that the medium to be pumped will never be in direct contact with the pump, which will thus not be contaminated by the medium to be pumped. The disadvantage of these pumps is that they give rise to a considerable pulsation of the flow and a significant wearing of the tubing, which gives rise to changed flow properties.In most peristaltic pumps, the displaceable pressure is obtained by arranging the tubing in a substantially semi-circular path with a fixed outer radius and bringing a number of rollers against the inner radius of the tubing to press it against the outer radius. In order to decrease wearing of the tubing, it is essential that no tangential forces appear between the rollers and the tubing and furthermore, the pressure of the rollers against the tubing must be kept within well defined limits. In order to provide this one could either mechanically adjust the deformation of the tubing, which normally takes place by changing the tubing, or to provide a defined pressure, either by using gravity or by using spring means, either individually on the different rollers or along the complete tubing path.

All these methods will however suffer from either a lack of adjustment to varying tubing properties or difficulties in adjusting the deformation of the tubing to optimal values.

According to the present invention there is provided a peristaltic pump for pumping a medium in an elastically deformable tubing, the pump comprising two opposite rigidly coupled jaws provided with cavities and a plurality of rollers suspended between the cavities at a certain internal distance around a substantially circular periphery, the tubing being arranged between the rollers and one of the cavities, and driving means coupled to the rollers for causing them to roll along the tubing and thereby push the contents of the tubing along the same, wherein the suspension of the rollers permits a certain radial displacement and the sides of the rollers remote from the jaws are in contact with an elastic device from which the rollers along at least one part of their path are subject to a resilient pressure.

The present invention will now be described by way of example with reference to the accompanying drawing, in which: Figure 1 schamatically shows a cross-section through a peristaltic pump; and Figures 2a and b show two very different view of jaws used in the pump according to Fig. 1.

In Fig. 1, references 1 and 2 denote two jaws which are fixed against each other by means of two snap-locks 11 and 1 2. The jaws are provided with two opposite cavities shaped as circular segments each covering an angle of somewhat less than 180 . Between the jaws a number of rollers 3 are journalled on a ring 5 in such a way that they can roll along the circular segments, the journalling being designed so as to admit a certain radial displacement of the rollers. The rollers are separated by spacing pieces 4, fixed to the ring 5. Between the rollers and the jaw 1, a tubing 10 in which the medium to be pumped is arranged.The tubing is arranged along the circular segment in a groove 13, and is attached to the jaw 1, before the jaw is locked to the jaw 2, in further grooves 14, 1 5 which are somewhat more narrow than the outer diameter of the tubing (Figs. 2a and 2b). An elastic device comprising a ring 6, four arms 7 and a hub 8 is arranged in contact with the rollers. In the centre of the hub a driving axle 9 is arranged, from which a tangential but no radial force is transferred to the hub.

The device hitherto described works in the following manner. The tubing 10 containing the medium to be pumped is stretched across the jaw 1 and is attached to the grooves 14 and 1 5. The radius of the cavities in the jaw 1 is chosen in such a way that the tubing when the jaw is attached to the opposite jaw 2 over the rollers 3 obtains the tension desired.

When this takes place the elastic ring 6 will be deformed and will be given a somewhat oval shape, as the segments of the jaws 1 and 2 cover an angle of somewhat less than 180 .

When the axle 9 rotates, the ring 6 will drive the rollers 3 along the tubing from right to left in the direction of rotation indicated in Fig. 1.

The four arms 9 are so resilient that they do not transfer any radial force against the ring but only a tangential force on the ring. The radial force on the tubing is thus defined by the difference between the radius of the path of the tubing and the rolling radius of the jaw when the counterforce from the tubing is not sufficient to move the rollers from the rolling path. The resilient force of the ring 6 will thus force the rollers towards the rolling path in the jaw whereby the ring will not give rise to a pressure on the rollers during a complete rotation but gives a successively increasing and decreasing pressure on the rollers when they are rolled on the tubing in the cavity of the jaw 1. Thereby the unwanted pulsation of the flow is reduced.

The device in the centre of the pump could of course be designed in different ways as long as resilient contact against the rollers from the elastic ring 6 is obtained. The arms 7 could thus be exchanged for rubber or by a design comprising carrier pins on the outer ring.

Claims

1. A peristaltic pump for pumping a medium in an elastically deformable tubing, the pump comprising two opposite rigidly coupled jaws provided with cavities and a plurality of rollers suspended between the cavities at a certain internal distance around a substantially circular periphery, the tubing being arranged between the rollers and one of the cavities, and driving means coupled to the rollers for causing them to roll along the tubing and thereby push the contents of the tubing along the same, wherein the suspension of the rollers permits a certain radial displacement and the sides of the rollers remote from the jaws are in contact with an elastic device from which the rollers along at least one part of their path are subject to a resilient pressure.

2. A pump according to claim 1, wherein driving means transferring a tangential force is coupled to the elastic device.

3. A pump according to claim 1 or 2, wherein the cavities are shaped as circular segments covering an angle of somewhat less than 180 .

4. A pump according to any preceding claim, wherein one of the jaws at the ends of the cavity is provided with grooves somewhat narrower than the diameter of the tubing so as to make it possible to attach the tubing in the grooves before locking the jaws together.

5. A peristaitic pump, substantially as herein described with reference to the accompanying drawing.