GB2173549A - Peristaltic pumps - Google Patents

Abstract

A peristaltic pump having within a cylindrical housing a rotor base 10 carrying three symmetrically disposed spindles 14 on which float respective pump rollers 16. The rollers are in rolling contact with one or more flexible pump tubes 6, 8 and with an inner ring member 18. The rollers and inner ring member rotate on a sun and planet principle and because the rollers float on their spindles the pump operates at low torque. The rollers 16 and ring member 18 may be of polyacetal resin. <IMAGE>

Description

SPECIFICATION Peristaltic pumps This invention relates to peristaltic pumps, the object of which is to provide such pumps which run on relatively low torque.

According to the invention there is provided a peristaltic pump having a generally cylindrical housing for containment of one or more flexible pump tubes, a rotor base and means for rotating the base within the housing, at least three spindles being symmetrically disposed about the axis of rotation of said base and upstanding therefrom, each said spindle carrying a roller for contact with the tube or tubes, each roller having a central cylindrical bore within which its respective spindle is housed, each said bore having a larger diameter than that of its spindle, and an inner ring member coaxial with the axis of rotation of the base and in contact with each of said rollers.

The pump functions on a sun and planet principle with the rollers being the planets. These rotate about the inner ring member which forms the sun.

The rollers float on their respective spindles because of the clearance therebetween, but rotate about the spindles in rolling contact with the flexible tube or tubes and with the inner ring member, which therefore also rotates.

Preferably the rollers are right cylinders and generally only 3, disposed 120 apart, are required.

A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure lisa plan view of the pump with a cover plate and a roller retaining plate removed to expose the working parts, and Figure 2 is a section on line A-A of Figure 1 but with the cover plate and roller retaining plate in position.

Referring to the drawing, the pump comprises a cylindrical housing 2, across the top of which is mounted a cover plate 4 (Figure 2). Around the inner circumference of the housing extend a pair of flexible pump tubes 6 and 8. A rotor base plate 10 is provided coaxially within housing 2 and is supported on a shaft 12 leading to a pump motor (not shown).

Extending upwardly on base plate 10 are three spindles 14which carry three respective rollers 16.

The rollers 16 are right cylinders having an internal bore which is slightly larger than the diameter of the spindles. Mounted coaxially with the shaft 12 is an inner ring member 18. The latter contacts the rollers 16 and these in turn are pressed into contact with the flexible tubes 6 and 8. A roller retaining plate 20 is secured to the spindles across the top of the rollers 16 and ring member 18 (Figure 2).

The operation of the pump is best observed from Figure 1, where the directions of rotation of the moving components are marked with arrows. As the shaft 12, rotor base plate 10, and spindles 14 rotate counterclockwise, the rollers 16 are forced to rotate in a clockwise direction around their own axes and in rolling contact with the flexible tubes 6 and 8 and ring member 18. The latter is therefore caused to rotate in a counterclockwise direction. The rolling motion of rollers 16 againsttheflexibletubes6and 8 causes fluid to flovv through the tubes in the normal peristaltic pump fashion.

For a reason which is not yet entirely understood, but which is believed to be due to the floating of rollers 16 on spindles 14, the pump operates at a lower torque than when the rollers are independently mounted on spindles 14 (without ring member 18) or when the rollers and ring member are geared together as in a normal sun and planet gear arrangement. The maximum tube compression is dictated by the difference between (i) the inner radius of the housing 2 and (ii) the sum of the roller 16 outer diameter and half the ring member 18 outer diameter. Standard peristaltic pump tubing may be employed. In the embodiment described the rollers 16 and ring member 18 were formed of polyacetal resin. The rollers 16 are always in contact with one or other of the flexible tubes 6 and 8. With two flexible tubes, two separate fluids may be pumped simultaneously.Alternatively such an arrangement may be employed to pump a single fluid by returning the latter from the exit of one tube to the entrance of the other tube, thus providing a double passage of fluid through the pump. The two tubes may also be replaced by a single tube extending completely around the inner circumference of housing 2.

1. A peristaltic pump having a generally cylindrical housing for containment of one or more flexible pump tubes, a rotor base and means for rotating the base within the housing, at least three spindles being symmetrically disposed about the axis of rotation of said base and upstanding therefrom, each said spindle carrying a roller for contact with the tube or tubes, each roller having a central cylindrical bore within which its respectiv 3 spindle is housed, each said bore having a larger diameter than that of its spindle, and an inner ring member coaxial with the axis of rotation of the base and in contact with each of said rollers.

2. A pump according'to claim 1 wherein there are three rollers and three spindles.

3. A pump according to claim 1 or 2 wherein the rollers are right cylinders.

4. A pump according to any of claims 1 to 3 wherein the inner ring member is a right cylinder.

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

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Peristaltic pumps This invention relates to peristaltic pumps, the object of which is to provide such pumps which run on relatively low torque. According to the invention there is provided a peristaltic pump having a generally cylindrical housing for containment of one or more flexible pump tubes, a rotor base and means for rotating the base within the housing, at least three spindles being symmetrically disposed about the axis of rotation of said base and upstanding therefrom, each said spindle carrying a roller for contact with the tube or tubes, each roller having a central cylindrical bore within which its respective spindle is housed, each said bore having a larger diameter than that of its spindle, and an inner ring member coaxial with the axis of rotation of the base and in contact with each of said rollers. The pump functions on a sun and planet principle with the rollers being the planets. These rotate about the inner ring member which forms the sun. The rollers float on their respective spindles because of the clearance therebetween, but rotate about the spindles in rolling contact with the flexible tube or tubes and with the inner ring member, which therefore also rotates. Preferably the rollers are right cylinders and generally only 3, disposed 120 apart, are required. A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure lisa plan view of the pump with a cover plate and a roller retaining plate removed to expose the working parts, and Figure 2 is a section on line A-A of Figure 1 but with the cover plate and roller retaining plate in position. Referring to the drawing, the pump comprises a cylindrical housing 2, across the top of which is mounted a cover plate 4 (Figure 2). Around the inner circumference of the housing extend a pair of flexible pump tubes 6 and 8. A rotor base plate 10 is provided coaxially within housing 2 and is supported on a shaft 12 leading to a pump motor (not shown). Extending upwardly on base plate 10 are three spindles 14which carry three respective rollers 16. The rollers 16 are right cylinders having an internal bore which is slightly larger than the diameter of the spindles. Mounted coaxially with the shaft 12 is an inner ring member 18. The latter contacts the rollers 16 and these in turn are pressed into contact with the flexible tubes 6 and 8. A roller retaining plate 20 is secured to the spindles across the top of the rollers 16 and ring member 18 (Figure 2). The operation of the pump is best observed from Figure 1, where the directions of rotation of the moving components are marked with arrows. As the shaft 12, rotor base plate 10, and spindles 14 rotate counterclockwise, the rollers 16 are forced to rotate in a clockwise direction around their own axes and in rolling contact with the flexible tubes 6 and 8 and ring member 18. The latter is therefore caused to rotate in a counterclockwise direction. The rolling motion of rollers 16 againsttheflexibletubes6and 8 causes fluid to flovv through the tubes in the normal peristaltic pump fashion. For a reason which is not yet entirely understood, but which is believed to be due to the floating of rollers 16 on spindles 14, the pump operates at a lower torque than when the rollers are independently mounted on spindles 14 (without ring member 18) or when the rollers and ring member are geared together as in a normal sun and planet gear arrangement. The maximum tube compression is dictated by the difference between (i) the inner radius of the housing 2 and (ii) the sum of the roller 16 outer diameter and half the ring member 18 outer diameter. Standard peristaltic pump tubing may be employed. In the embodiment described the rollers 16 and ring member 18 were formed of polyacetal resin. The rollers 16 are always in contact with one or other of the flexible tubes 6 and 8. With two flexible tubes, two separate fluids may be pumped simultaneously.Alternatively such an arrangement may be employed to pump a single fluid by returning the latter from the exit of one tube to the entrance of the other tube, thus providing a double passage of fluid through the pump. The two tubes may also be replaced by a single tube extending completely around the inner circumference of housing 2. CLAIMS

1. A peristaltic pump having a generally cylindrical housing for containment of one or more flexible pump tubes, a rotor base and means for rotating the base within the housing, at least three spindles being symmetrically disposed about the axis of rotation of said base and upstanding therefrom, each said spindle carrying a roller for contact with the tube or tubes, each roller having a central cylindrical bore within which its respectiv 3 spindle is housed, each said bore having a larger diameter than that of its spindle, and an inner ring member coaxial with the axis of rotation of the base and in contact with each of said rollers.

2. A pump according'to claim 1 wherein there are three rollers and three spindles.

3. A pump according to claim 1 or 2 wherein the rollers are right cylinders.

4. A pump according to any of claims 1 to 3 wherein the inner ring member is a right cylinder.

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