Process for Peristaltic Pump Control

Abstract

A peristaltic pump is provided comprising squeezing elements moved by at least one actuator, which squeezing elements act on a tube in which a medium is conveyed, with the squeezing elements successively getting into and out of a squeezing engagement with the tube. A process for controlling the peristaltic pump comprises measuring over time a fluidic parameter representative for the flow rate of the medium through the tube, determining the relative undulation of the flow rate of the medium from the measured temporal course of the fluidic parameter, and smoothing the undulation by adjusting the progression speed of the squeezing elements on the basis of the determined undulation of the flow rate.

Description

BACKGROUND OF THE INVENTION[0001]The present invention is directed to peristaltic pumps and, in particular, to a process for peristaltic pump control.[0002]Peristaltic pumps are displacement pumps in which the medium to be conveyed is guided through a tube which, in most cases, is U-shaped, but may also be linear or arranged along largely any path. Said tube is supported in the body of the pump and is pinched successively by squeezing elements such as rolls or sliding blocks, which are moved by an actuator. Said actuator is usually designed as a rotor. The rotation of the rotor moves the pinched point generated by the squeezing elements along the tube and thus pushes forward a volume of the medium to be conveyed in the tube, which volume is located ahead of the pinched point. Simultaneously, a negative suction pressure is generated at the tube inlet. In alternative embodiments of peristaltic pumps, the actuators are designed as linear drives, or a plurality of squeezing elements are...

AI Technical Summary

Benefits of technology

[0008]Although the present invention is not limited to specific advantages or functionality, it is noted that the present invention provides a solution for the illustrated problems of the prior art. In particular, the undulation of the delivery rate of peristaltic pumps is reduced by the present invention, and a peristaltic pump control is provided which enables continuous calibration of a peristaltic pump during operation with regard to the flow rate and the undulation thereof. Thereby, the undulation of such peristaltic pumps is reduced which do not constitute a closed unit, but in which the tube is a replacement part or a consumption material which is replaced at relatively short intervals. After all, it should be possible by means of the present invention to reduce the required sample volume of the sample medium conveyed through peristaltic pumps in laboratory equipment, in particular blood analysis devices.

Problems solved by technology

However, peristaltic pumps have the disadvantage that variable delivery rates occur because of varying tube properties and wear of the tube.

This influence of the tube properties and of the age of the tube is disadvantageous especially for blood analysis devices in which the tube is very often a consumer item and, together with other fluidic elements, is often integrated in a so-called fluid pack which is replaced at regular intervals.

The attainment of this object is hampered by the undulation of the delivery rate of peristaltic pumps in blood analysis devices.

The drawback is that a residual undulation remains for all pump configurations except for that with the minimum undulation.

However, since the actual flow rate of the sample is not constant, but exhibits an undulation due to the properties of the peristaltic pump, it may happen that the sample stops ahead of or after the sensor, depending on the current flow rate.

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