GB2290582A - Peristaltic pumps - Google Patents

Abstract

In a peristaltic pump internal support walls 7, 12, 13 are arranged to minimise pulsing in the output from the pump. Flexible pipe 2 is supported by a substantially semi-circular wall 7 which is joined to walls 12 and 13 of larger radius centred at Y and Z respectively, the walls 12 and 13 supporting the pipe 2 between its portion supported by wall 7 and the inlet 3 and outlet 6 respectively. <IMAGE>

Description

PUMPS This invention relates to pumps and is particularly concerned with peristaltic pumps.

In a peristaltic pump a flexible pipe, usually of synthetic plastics material, extends from an inlet of the pump and around a substantially circular path within a housing of the pump to an outlet of the pump. The pipe is confined to its circular path within the housing by an internal wall of the housing and this wall supports the pipe against the action of rollers carried by a rotor which bear on the pipe along its circular path so as to squeeze it closed, typically at two opposed zones. As the rotor rotates the closed zones effectively move around the run of the pipe that is confined to the circular path and this effect serves to draw fluid into the pipe at the inlet of the pump and expel it from the pipe at the outlet.

In known peristaltic pumps the internal wall that supports the pipe and confines it to its circular path extends for about 1800 substantially mid-way between the inlet and the outlet of the pump. The runs of the pipe between the inlet and the support wall, and between the support wall and the outlet, are substantially unsupported. The pipe is always open along these runs, the rollers carried by the rotor bearing on the pipe to close it only on the run of the pipe that extends around the circular path, so that the closed zones are only formed around the circular run of the pipe. During each revolution of the rotor each roller first closes the pipe at the commencement of the circular run (in the direction of fluid flow through the pump) and finally permits the pipe to open at the termination of the circular run.

The output of pumped fluid from a peristaltic pump as so far described tends to be of a pulsating nature and this is undesirable in some circumstances.

According to the present invention there is provided a peristaltic pump having a flexible pipe that extends from an inlet of the pump and around a substantially circular path within a housing of the pump to an outlet of the pump, the pipe being confined within the housing of the pump by an internal support wall; a rotor arrangement within the housing disposed for bearing, during rotation, on the run of the pipe that is confined to be substantially circular so as to be able to close this run of the pipe at at least two spaced apart zones, said internal support wall supporting the pipe against this action of the rotor arrangement; and there being further internal support walls that support the runs of the pipe between the inlet and the substantially circular run of the pipe, and between the substantially circular run of the pipe and the outlet, these further internal support walls being disposed for supporting the pipe against the action of the rotor during rotation to an increasing extent in the direction of pumped fluid flow from the inlet to the circular run of the pipe, and to a decreasing extent in the direction of pumped fluid flow from the circular run of the pipe to the outlet.In operation the effect of the support given by the further internal support walls is that the rotor arrangement gradually closes the pipe each time the effect of the rotor arrangement approaches the circular run of the pipe, and permits the pipe gradually to open each time the effect of the rotor arrangement moves away from the circular run. Pulsing in the output of pumped fluid is thereby minimised.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a diagrammatic sectional view of the peristaltic pump, Figure 2 is a perspective view of the part of the pump of Figure 1, and Figure 3 is a view as Figure 1 with preferred dimensions added thereto.

Referring to the Figures, the peristaltic pump 1 has a flexible pipe 2 of synthetic plastics material that extends from an inlet 3 of the pump via a run 4 that extends around a substantially circular path within a housing 5 of the pump to an outlet 6. The run 4 of the pipe is confined to its substantially circular path by an internal support wall 7 of the housing 5 centred at X in Figure 1 and that extends for 1800 substantially mid-way between the inlet 3 and the outlet 4.

Disposed so as to be encircled by the run 4 of the pipe 2 there is a rotor arrangement 8 that includes two diametrically opposed rollers 9. The rollers 9 are disposed such that during each revolution of the rotor arrangement 8 each roller 9 in turn runs onto the run 4 of the pipe 2 supported by the internal support wall 7, the roller then squeezing the pipe 4 against the wall 7 to close the run 4 at a zone 10 which moves around the run 4 as the rotation of the rotor arrangement 8 continues. As there are two rollers 9 the rotor arrangement 8 is able to close the run 4 at two spaced apart zones.

The pump as thus far described is of conventional construction.

Within the housing 5 there is a block 11 (Figure 2) which includes two further internal support walls 12, 13 for supporting the pipe 2. The block 11 can be in a single piece as shown, or can be an assembled multi-piece arrangement. The wall 12 is disposed to support the run 14 of the pipe 2 that extends from the inlet 3 to the run 4. The wall 13 is disposed to support the run 15 of the pipe 2 that extends from the run 4 to the outlet 6.

Referring to Figure 1, the dotted line 7A depicts an imaginary extension of the support wall 7 through a full circle. It will be seen that the wall 12 follows a curve that gradually approaches the curve of the wall 7 whilst the wall 13 follows a curve that gradually departs from the curve of the wall 7.

More specifically, and referring to Figure 3 which is as Figure 1 so that reference numerals are omitted, but in which dimensions of a preferred embodiment are given, these dimensions are: Radius of wall 7, centred at X in Figure 1 24.25 mm Radius of wall 12, centred at Y in Figure 1 25.25 mm Radius of wall 13, centred at Z in Figure 1 25.25 mm Displacement of centre Y from centre X in the direction away from meeting of wall 12 with wall 7 1.00 mm Displacement of centre Z from centre X in the direction away from meeting of wall 13 with wall 7 1.00 mm Other dimensions given in Figure 3 are that the radius of an intermediate curved portion of each wall 12, 13 that supports the pipe run 14 or 15 at a zone intermediate the inlet 3 or the outlet 6 and the run 4 is 6.00 mm, and that from this intermediate curved portion to the part that is at radius 25.25 mm each wall 12, 13 follows a straight path inclined at 5 to a line tangential to the intermediate curved portion at this termination of the intermediate curved portion.

The dimensions given on Figure 3 are the most preferred dimensions. In any event, for a radius of the wall 7 of 24.25 mm, the other dimensions should lie within ranges as follows: Radius of wall 12 24.75 - 25.75 mm Radius of wall 13 24.75 - 25.75 mm Displacement of centre Y 0.50 - 1.50 mm Displacement of centre Z 0.50 - 1.50 mm Radius of intermediate curved portion of wall 12 5.00 - 10.00 mm Radius of intermediate curved portion of wall 13 5.00 - 10.00 mm Angle of inclination 2.50 - 7.50 It is to be noted that all dimensions have been given based on a radius of 24.25 mm for the internal support wall 7. For any embodiment in which this wall radius is other than 24.25 mm, all the dimensions will be in proportion thereto as are the dimensions given above to an internal support wall 7 radius of 24.25 mm.

In operation the inlet 3 is connected to a reservoir of fluid to be pumped and the outlet 6 is connected to whatever it is that it is desired to pump fluid to. For example the reservoir could be a tank of herbicide and the outlet 3 could be connected to supply herbicide to the discharge nozzle of a herbicide sprayer. It is particularly desirable in such a use that there should be a substantially steady, consistent, discharge of herbicide from the nozzle to ensure full coverage of the area being sprayed.

The rotor arrangement 8 is driven to rotate clockwise as viewed in Figure 1, indicated by arrow VIII.

When either of the rollers 9 is at its lowermost position as viewed in Figure 1, that is it is at the commencement of the curve of the wall 12 that leads to the wall 7, the pipe 2 is able to adopt its maximum open condition. As the roller 9 moves on the effect of the wall 12 gradually approaching the curve of the wall 7 is that the squeezing effect of the roller 9 on the pipe 2 gradually increases and so the roller 9 gradually squeezes the pipe 2 closed, until, at the commencement of the run 4, the closed zone 10 is formed. As the rotation continues, this closed zone moves around the run 4. At the termination of the run 4 the effect of the wall 13 gradually departing from the curve of the wall 7 is that the squeezing effect of the roller 9 gradually diminishes and the pipe 2 is permitted gradually to open again. These effects are repeated as each roller 9 moves around the pipe 2, with the result that fluid is drawn into the inlet 3 (arrow III) to be passed around the run 4 of the pipe 2 (arrows IV) and expelled from the outlet 6 (arrow VI). The gradual closing and opening of the pipe 2 that takes place has the effect of minimising pulsations in the output from the outlet 6.

Claims (2)

ClAIMS

1. A peristaltic pump having: a flexible pipe that extends from an inlet of the pump and around a substantially circular path within a housing of the pump to an outlet of the pump, the pipe being confined within the housing of the pump by an internal support wall; and a rotor arrangement within the housing disposed for bearing, during rotation, on the run of the pipe that is confined to be substantially circular so as to be able to close this run of the pipe at at least two spaced apart zones, said internal support wall supporting the pipe against this action of the rotor arrangement; and there being further internal support walls that support the runs of the pipe between the inlet and the substantially circular run of the pipe, and between the substantially circular run of the pipe and the outlet, these further internal support walls being disposed for supporting the pipe against the action of the rotor during rotation to an increasing extent in the direction of pumped fluid flow from the inlet to the circular run of the pipe, and to a decreasing extent in the direction of pumped fluid flow from the circular run of the pipe to the outlet.

2. A peristaltic pump substantially as herein described with reference to the accompanying drawings.