AU2002100074A4 - Epicycloidal peristaltic pump - Google Patents

Description

Epicycloidal Peristaltic Pump: This invention describes a novel arrangement consisting of a pump body with an essentially cylindrical track and a concentric, tube-enclosing groove formed radially outwards in which the flanges of the pumping wheels run. The flanged wheels are driven around the track by a rotating drive cylinder in contact with their inner tangential edge and are located radially by their shoulders running in contact with the track.

The path followed by the running shoulder is therefore cycloidal. The path followed by the flange outer edge, which is in contact with the tube and outside the shoulder track radius, is epicycloidal and therefore has, in addition to the normal forward component of its motion, a slight retrograde motion as seen by the elastomeric tube. The flange therefore simultaneously lightly compresses and occludes the elastomeric tube in the normal peristaltic fashion and additionally produces an action which counteracts the otherwise distorting, prograde stretching force normally encountered in peristaltic pumps.

This invention removes the need to have the elastomeric tube firmly located because the epicycloidal motion maintains the tube in position radially, axially and longitudinally. It is only necessary to locate the tube at the entry and exit points of the tube-encompassing groove.

This invention also provides for a further groove machined excentrically so that the remaining sector performing the peristaltic pumping action is always somewhat wider than the angle spanned by at least two rollers in the tube compression phase of the rotation.

The tapered arcuate space resultant between the concentric groove and the eccentric groove allows the approach and departure of the pumping rollers to be less abrupt in order to reduce pulsatility. The tube has the freedom to move in this phase and to behave conformally.

This invention also ensures reduced stress, wear and power consumption by utilising rolling contact throughout. Light friction is used to impart movement to the flanged pumping rollers by having the driving surface of the central drive rotor fitted with a rubber surface.

This invention ensures the regular spacing of the flanged rollers by incorporating grooved cage rollers which roll freely and slightly loosely along the path bordered by the cylindrical track and the adjacent flanges of the rollers.

In one embodiment of this invention the construction of the pump could consist typically of a generally cylindrical body attached axially to a stepping motor or geared DC motor. This body could have a cylindrical roller track machined parallel to the cylinder axis and a tube-encompassing groove machined concentrically radially outwards.

A second tube-encompassing groove could be machined eccentrically by an amount which would produce a gap, on the intake and the output sectors, equal to the outside diameter of the elastomeric tube along a sector angle preferably not less than the angle between the pumping rollers.

A central driving rotor could be fitted to the drive shaft of the motor assembly and be of such a size as to contact the inner tangential edge of the flange of the pumping roller while ensuring the shoulders of the same roller contacts the cylindrical track. The depth of the concentric tube-encompassing groove is such that the flange contacts and then lightly compresses the tube in an epicycloidal fashion.

Claims (4)

1. This invention describes a novel epicycloidal action which provides improved performance of peristaltic pumps.

2, This invention provides improved reliability, reduced wear, stress and friction and reduces power requirements of peristaltic pumps.

3. This invention enables reduction in manufacturing cost and complexity of peristaltic pumps and reduces assembly and maintenance effort.

4. This invention improves fluid delivery characteristics of peristaltic pumps.