PERISTALTIC PUMPS

Abstract

A peristaltic pump comprises a drivable rotor, having at least one pressing member, and a housing comprising a cylindrical stator in which the rotor is rotatable. Flexible tubing, having an inlet side and an outlet side, extends circumferentially around the cylindrical stator against an inner wall. The peristaltic pump includes a radially deformable ring positioned between the rotor and the circumferentially extending flexible tubing. The ring is deformed by the pressing member upon rotation of the rotor and this compresses the flexible tubing against the inner wall of the cylindrical stator to convey liquid along the flexible tubing. The radially deformable ring includes a ring anchor which prevents rotation of the radially deformable ring during rotation of the rotor. The ring anchor is engaged with the housing to secure the ring anchor to the housing whilst allowing reciprocal movement of the ring anchor in a radial direction.

Claims

1. A peristaltic pump comprising: a drivable rotor having at least one pressing member; a housing comprising a cylindrical stator in which the rotor is rotatable; flexible tubing having an inlet side and an outlet side, the flexible tubing extending circumferentially around the stator against an inner wall; a radially deformable ring positioned between the rotor and the circumferentially extending flexible tubing, the ring being deformable by the at least one pressing member upon rotation of the rotor to compress the flexible tubing against the inner wall of the cylindrical stator to thereby convey liquid along the flexible tubing; wherein the inlet side and the outlet side of the flexible tubing are arranged side-by-side so that the flexible tubing extends in a substantially radial direction outwardly away from the cylindrical stator; wherein the radially deformable ring includes a ring anchor projecting radially outwardly in a radial direction from the radially deformable ring and is located between the inlet side and the outlet side of the flexible tubing; characterised in that: the ring anchor is mounted to the housing to secure the ring anchor to the housing whilst allowing reciprocal movement of the ring anchor in the radial direction.

2. A peristaltic pump according to claim 1, wherein the ring anchor has a housing engaging protrusion that is reciprocally mounted within a radially extending sub-housing formed as part of the housing.

3. A peristaltic pump according to claim 2, wherein: the sub-housing comprises a slot extending in the radial direction; and the housing engaging protrusion of the ring anchor is mounted through the slot to allow reciprocal movement of the ring anchor in the radial direction along a length of the slot.

4. A peristaltic pump according to claim 3, wherein: the housing engaging protrusion of the ring anchor is elongated in the radial direction along a length of the slot such that a length of the housing engaging portion in the radial direction is at least 50% greater than a width of the slot.

5. A peristaltic pump according to claim 2, wherein: the housing engaging protrusion of the ring anchor comprises a thickened mounting portion formed at a radially outer end of the ring anchor; and the sub-housing comprises an opening at a radially inner end through which the ring anchor passes, the opening being narrower than the thickened mounting portion of the ring anchor to allow reciprocal movement of the thickened mounting portion of the ring anchor along a radial length of the sub-housing whilst maintaining the ring anchor within the sub-housing.

6. A peristalic pump according to claim 5, wherein: the housing engaging protrusion of the ring anchor is elongated in the radial direction along radial length of the sub-housing such that a length of the housing engaging protrusion along the radial length is at least 50% greater than a width of the sub-housing.

7. A peristaltic pump according to claim 1, wherein the housing has a ring anchor engaging protrusion that is reciprocally mounted within a radially extending sub-housing formed as part of the ring-anchor.

8. A peristaltic pump according to claim 7, wherein: the ring anchor engaging protrusion of the housing comprises an axially extending finger; the sub-housing of the ring anchor comprises a radially extending slot formed through the ring anchor; and the axially extending finger is mounted within the slot.

9. A peristaltic pump according to claim 8, wherein: the ring anchor engaging protrusion of the housing is elongated along a direction of the radially extending slot of the ring anchor such that a length of the ring anchor engaging protrusion along the direction of the radially extending slot is at least 50% greater than width of the radially extending slot.

10. A peristaltic pump according to claim 7, wherein: the ring anchor engaging protrusion of the housing comprises an axially extending portion having a thickened mounting part at a radially inner end and a thinner part extending radially outwards from the thickened mounting part; and the sub-housing of the ring anchor is formed at a radially outer end of the ring anchor and comprises a radially extending slot having an opening at a radially outer end, the thinner part of the ring anchor engaging protrusion extending through the opening, the opening being narrower than the thickened mounting part of the housing to allow reciprocal movement of the ring anchor along a radial length of the sub-housing whilst maintaining the ring anchor engaging protrusion within the sub-housing of the ring anchor.

11. A peristaltic pump according to claim 10, wherein: the thickened mounting part of the ring anchor engaging protrusion is elongated along a direction of the radially extending slot of the ring anchor such that a length of the thickened mounting part along the direction of the radially extending slot is at least 50% greater than width of the radially extending slot.

12. A peristaltic pump according to claim 1, wherein the radially deformable ring is formed of polyamide(nylon) (PA), polypropylene (PP), polyethylene (PE), polyoxymethylene(acetal) (POM), polyethylene terephthalate (PET), or a thermoplastic elastomer (TPE).

13. A method for assembling a peristaltic pump according to claim 1, the method comprising: locating the flexible tubing circumferentially around the radially deformable ring and in contact therewith, with the inlet side and the outlet side of the flexible tubing arranged side-by-side on either side of the ring anchor; positioning the flexible tubing and the radially deformable ring in the cylindrical stator with the flexible tubing arranged against the inner wall of the cylindrical stator; securing the ring anchor to the housing such that reciprocal movement of the ring anchor in the radial direction is possible; and fitting the rotor in the cylindrical stator by simultaneously rotating the rotor and pressing the rotor into the centre of the radially deformable ring.

Description

DRAWINGS

[0039] FIG. 1 is two cross-sections through a first embodiment of a peristaltic pump according to the present invention with a rotor in different rotational positions;

[0040] FIG. 1A is two cross-sections through a modified version of the first embodiment shown in FIG. 1;

[0041] FIG. 1B shows details of the components of FIG. 1A;

[0042] FIG. 2 is two cross-sections through a second embodiment of a peristaltic pump according to the present invention with a rotor in different rotational positions;

[0043] FIG. 2A is two cross-sections through a modified version of the second embodiment shown in FIG. 2;

[0044] FIG. 2B shows details of the components of FIG. 2A;

[0045] FIG. 3 is an exploded diagram of the components of the first embodiment shown in FIG. 1;

[0046] FIG. 4 is an exploded diagram showing the radially deformable ring and the housing of the second embodiment shown in FIG. 2;

[0047] FIG. 5 is two cross-sections through a third embodiment of a peristaltic pump according to the present invention with a rotor in different rotational positions;

[0048] FIG. 5A is two cross-sections through a modified version of the third embodiment shown in FIG. 5;

[0049] FIG. 5B shows details of the components of FIG. 5A;

[0050] FIG. 6 is two cross-sections through a fourth embodiment of a peristaltic pump according to the present invention with a rotor in different rotational positions;

[0051] FIG. 6A is two cross-sections through a modified version of the fourth embodiment shown in FIG. 6;

[0052] FIG. 6B shows details of the components of FIG. 6A;

[0053] FIG. 7 is an exploded diagram of the components of the third embodiment shown in FIG. 5; and

[0054] FIG. 8 is an exploded diagram showing the radially deformable ring and the housing of the fourth embodiment shown in FIG. 6.

[0055] A peristaltic pump 10 includes a housing 11 comprising a cylindrical stator 12. Although not shown, the housing 11, including the cylindrical stator 12, can be integrally formed, for example as a one-piece moulding, with a liquid container from which liquid is to be dispensed or can be removably mountable on a liquid container.

[0056] Four embodiments of peristaltic pumps 10 according to the present invention are shown in the Figures. The components common to the four embodiments are described immediately below. For clarity, the same reference numerals are used to refer to components common to each of the four embodiments.

[0057] The pumps 10 include a rotor 14, typically formed of a moulded substantially rigid plastics material. The rotor 14 includes two pressing members in the form of two diametrically opposed lobes 16 which are integrally formed with, and project radially outwardly from, a spindle 18. Each lobe 16 has a curved or arcuate pressing surface 15 whose radius relative to the spindle axis increases gradually and smoothly. In the illustrated embodiments, the rotor 14 includes two diametrically opposed lobes 16 but it will be appreciated that the rotor 14 can include any suitable number of lobes 16. The spindle 18 includes a central drive aperture 20 which can be engaged by an external rotary drive (not shown) such as the drive shaft of an electric motor.

[0058] The peristaltic pumps 10 include flexible tubing 22 which can be formed of any suitable resilient plastics material such as polyvinyl chloride. The flexible tubing 22 has an inlet side 24 through which liquid is delivered to the peristaltic pump 10 and an outlet side 26 through which liquid is delivered from the peristaltic pump 10. The inlet side 24 and outlet side 26 are designated with respect to the normal direction of rotation of the rotor 14 (clockwise in the accompanying drawings). The inlet side 24 is typically connected to a liquid outlet port of a liquid container (not shown) and the outlet side 26 is arranged to deliver the liquid to a desired location. The flexible tubing 22 extends circumferentially around the cylindrical stator 12 against an inner wall 12a and the inlet side 24 and the outlet side 26 are arranged side-by-side, at circumferentially adjacent positions around the cylindrical stator 12. The inlet side 24 and the outlet side 26 extend outwardly away from the cylindrical stator 12 in a substantially radial direction.

[0059] A radially deformable ring 28, comprising a suitable resiliently deformable material (typically a plastics material), is positioned between the rotor 14 and the circumferentially extending flexible tubing 22. The deformable ring 28 is contacted by the lobes 16 of the rotor 14 and is deformed radially outwardly by the lobes 16. The radially outward deformation of the deformable ring 28 compresses the flexible tubing 22 against the inner wall 12a of the cylindrical stator 12 and, thus, as the rotor 14 is rotated by an external rotary drive, the compression of the flexible tubing 22 between the deformable ring 28 and the inner wall 12a conveys liquid along the flexible tubing 22 by peristaltic action, between the inlet side 24 and the outlet side 26. Although the liquid is normally conveyed from the inlet side 24 to the outlet side 26 of the flexible tubing (by rotating the rotor 14 in the clockwise direction as viewed in FIGS. 1a and 1b), the flow direction can be easily reversed and it will be understood that the desired flow direction can be selected by simply selecting a clockwise or anti-clockwise direction of rotation for the external rotary drive.

[0060] The deformable ring 28 includes a ring anchor 30 which projects radially from the deformable ring 22. The ring anchor 30 is located between the inlet side 24 and the outlet side 26 of the flexible tubing 22 and is engaged with the housing to prevent circumferential movement, whilst allowing limited reciprocal movement of the ring anchor 30 in a radial direction. This is achieved in different manners in each of the four embodiments, as described below. Thus, it will be understood that the ring anchor 30 prevents the deformable ring 28 from being rotated by the rotor 14 as the rotor 14 rotates in the cylindrical stator 12. If the ring anchor 30 was not provided, the deformable ring 28 would be caused to rotate by the rotor 14 and this would result in unwanted stretching and wearing of the flexible tubing 22 between the deformable ring 28 and the inner wall 12a of the cylindrical stator 12. The limited reciprocal movement of the ring anchor 30 in a radial direction allows the deformable ring 22 to deform under the action of the rotor 14 without excessive stress being exerted on the ring anchor 30.

[0061] The embodiments of the invention differ in the engagement of the ring anchor 30 with the housing 11. In the first embodiment of the pump 10 shown in FIGS. 1 and 3, a sub-housing consisting of a radially extending slot 60 is formed in the housing and an axially extending housing engaging protrusion 62 (visible in FIG. 3) is formed adjacent a radially outer end of the ring anchor 30. The housing engaging protrusion 62 extends through the radially extending slot 60 to secure the ring anchor 30 within the housing 11. In this manner, the ring anchor 30 is secured to the housing 11 against rotational movement but is free to reciprocate in the radial direction, as may be required during operation of the pump and as illustrated in FIG. 1.

[0062] In the second embodiment of the pump 10 shown in FIGS. 2 and 4, the housing 11 comprises an engaging protrusion 70 extending axially from the housing 11. The ring anchor 30 has a radially extending slot 72 formed through the ring anchor adjacent a radially outer end. The engaging protrusion 70 is located through the radially extending slot 72. In this manner, the ring anchor 30 is secured to the housing 11 against rotational movement but is free to reciprocate in the radial direction, as may be required during operation of the pump and as illustrated in FIG. 2.

[0063] In the third embodiment of the pump shown in FIGS. 5 and 7 the ring anchor 30 comprises a thickened mounting portion 80 formed at a radially outer end and the a sub-housing 82 is formed on the housing for containing the thickened mounting portion 80 of the ring anchor 30. The sub-housing 82 has an opening 84 at a radially inner end through which the ring anchor 30 passes, the opening 84 being narrower than the thickened mounting portion 80 of the ring anchor 30. The sub-housing 82 has an internal length extending in a radial direction along with the thickened mounting portion 80 can reciprocate, whilst maintaining the ring anchor 30 within the sub-housing 82. In this manner, the ring anchor 30 is secured to the housing 11 against rotational movement but is free to reciprocate in the radial direction, as may be required during operation of the pump and as illustrated in FIG. 5.

[0064] In the fourth embodiment of the pump shown in FIGS. 6 and 8 the housing 11 comprises a ring anchor engaging protrusion 90 consisting of an axially extending portion having a thickened mounting part 92 at a radially inner end and a thinner part 94 extending radially outwards from the thickened mounting part. The ring anchor 30 comprises a sub-housing 96 formed at a radially outer end. The sub-housing 96 has a radially extending slot 98 having an opening 100 at a radially outer end. The thinner part 94 of the ring anchor engaging protrusion 90 extends through the opening 100, the opening 100 being narrower than the thickened mounting part 92 to allow reciprocal movement of the ring anchor 30 along a radial length of the sub-housing 96 whilst maintaining the ring anchor engaging protrusion within the sub-housing of the ring anchor. In this manner, the ring anchor 30 is secured to the housing 11 against rotational movement but is free to reciprocate in the radial direction, as may be required during operation of the pump and as illustrated in FIG. 6.

[0065] In all embodiments of the invention it may be advantageous that any engaging portion of the ring anchor 30 and/or portion of the housing 11 that engages with the ring anchor 30 is enlongated to minimise rotation of the deformable ring 28 during operation of the peristaltic pump 10. In particular, if an engaging portion of the ring anchor 30 and/or portion of the housing 11 that engages with the ring anchor 30 is not sufficiently elongated then slight pivoting can occur during rotation of the rotor 14. This can result in pressure being applied to the side of the flexible tubing 22 on the outlet side 26. This can lead to eventual deformation and impaired performance of the peristaltic pump 10. Embodiments of the invention with elongated portions are shown in FIGS. 1A, 1B, 2A, 2B, 5A, 5B, 6A, and 6B and are described below.

[0066] In the modified version of the first embodiment of the pump 10 that is shown in FIGS. 1A and 1B the house engaging protrusion 62 is elongated as compared to the embodiment of FIGS. 1 and 3. In the embodiment of FIGS. 1 and 3, the house engaging protrusion 62 is substantially cylindrical with a radius R. In the modified version of FIGS. 1A and 1B the house engaging protrusion 62 is elongated to have a maximum length that is 3 R; that is the house engaging protrusion 62 is elongated in a direction parallel to the length of the radially extending slot 60 by 50% as compared to the cylindrical house engaging protrusion 62 of the embodiment of FIGS. 1 and 3.

[0067] This elongation prevents rotation during operation of the pump 10. It is to be understood that, although the elongation shown in FIGS. 1A and 1B is 50%, greater elongation in alternative embodiments possible.

[0068] In the modified version of the second embodiment of the pump 10 that is shown in FIGS. 2A and 2B the engaging protrusion 70 of the housing 11 is elongated as compared to the engaging protrusion 70 of the embodiment of FIGS. 2 and 4. The engaging protrusion 70 of FIG. 2 is substantially cylindrical and has a radius R. The engaging protrusion of FIGS. 2A and 2B is elongated to have a maximum length that is 3 R; that is the engaging protrusion 70 is elongated in a direction parallel to the length of the radially extending slot 72 by 50% as compared to the cylindrical engaging protrusion 70 of the embodiment of FIGS. 2 and 4. It is to be understood that, although the elongation shown in FIGS. 2A and 2B is 50%, greater elongation in alternative embodiments possible.

[0069] In the modified version of the third embodiment of the pump 10 that is shown in FIGS. 5A and 5B the thickened mounting portion 80 of the ring anchor 28 is elongated as compared to the thickened mounting portion 80 of the embodiment of FIGS. 5 and 7. The thickened mounting portion 80 of FIGS. 5 and 7 is substantially cylindrical and has a radius R. The thickened mounting portion 80 of FIGS. 5A and 5B is elongated to have a maximum length that is 3 R; that is the thickened mounting portion 80 is elongated in a direction parallel to the radially extending length of the sub-housing 82 by 50% as compared to the thickened mounting portion 80 of the embodiment of FIGS. 5 and 7. It is to be understood that, although the elongation shown in FIGS. 5A and 5B is 50%, greater elongation in alternative embodiments possible.

[0070] In the modified version of the fourth embodiment of the pump 10 that is shown in FIGS. 6A and 6B the thickened mounting part 92 of the housing 11 is elongated as compared to the thickened mounting part 92 of the embodiment of FIGS. 6 and 8. The thickened mounting part 92 of FIGS. 6 and 8 is substantially cylindrical and has a radius R. The thickened mounting part 92 of FIGS. 6A and 6B is elongated to have a maximum length that is 3 R; that is the thickened mounting part 92 is elongated in a direction parallel to the length of the radially extending slot 98 by 50% as compared to the thickened mounting part 92 of the embodiment of FIGS. 6 and 8. It is to be understood that although the elongation shown in FIGS. 6 and 8 is 50%, greater elongation in alternative embodiments possible.

[0071] The method of assembling a peristaltic pump 10 will now be described with reference to the Figures. Initially, the flexible tubing 22 is located around the deformable ring 28 so that it contacts the radially outer surface of the deformable ring 28 and so that the inlet side 24 and the outlet side 26 of the flexible tubing 22 are arranged side-by-side on either side of the ring anchor 30. The assembled flexible tubing 22 and deformable ring 28 are then compressed, for example by squeezing, to a sufficient size to enable them to be pushed into the cylindrical stator 12. When inserting the deformable ring into the stator 12 the ring anchor 30 is engaged with the housing 11.

[0072] Once the flexible tubing 22 and deformable ring 28 have been positioned in the cylindrical stator 12 the rotor 14 can be fitted and this is achieved by pushing the rotor 14 into the centre of the deformable ring 28 and at the same time rotating the rotor 14 by a small amount. Once assembled, the central drive aperture 20 can be engaged by an external rotary drive which can be operated to rotate the rotor 14.

[0073] Once the flexible tubing 22 and deformable ring 28 have been positioned in the cylindrical stator 1, the rotor 14 can be fitted and this is achieved by pushing the rotor 14 into the centre of the deformable ring 28, and at the same time rotating the rotor 14 by a small amount. Once assembled, the central drive aperture 20 can be engaged by an external rotary drive which can be operated to rotate the rotor 14.

[0074] Although exemplary embodiments have been described in the preceding paragraphs, various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments. Each feature disclosed in the specification, including the claims and drawings, may be replaced by alternative features serving the same, equivalent or similar purposes, unless expressly stated otherwise.

[0075] Unless the context clearly requires otherwise, throughout the description and the claims, the words comprise, comprising, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of including, but not limited to.

[0076] Any combination of the above-described features in all possible variations thereof is encompassed by the present invention unless otherwise indicated herein or otherwise clearly contradicted by context.