GB2230301A

GB2230301A - Adjustable peristaltic pump

Info

Publication number: GB2230301A
Application number: GB8907878A
Authority: GB
Inventors: Hermann Meili
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1989-04-07
Filing date: 1989-04-07
Publication date: 1990-10-17
Also published as: GB8907878D0

Abstract

In a peristaltic pump, e.g. for a floor cleaning machine, comprising a rotor having two or more rollers 2 mounted thereon, a stator 3, and a flexible tube 4 supported on a separate part 5 of the stator, the distance between said separate part and the rotational axis of the rotor can be continuously varied during operation to vary the output, and the rollers are attached to the rotor by means of flexible arms 6. The separate part 5 may be adjusted by a screw or lever or by an electric motor. A non-return valve may be provided at the downstream end of the tube 4. <IMAGE>

Description

PERISTALTIC PUMP The present invention relates to a peristaltic pump.

More in particular, it relates to a peristaltic pump comprising a rotor having two or more rollers mounted thereon, a stator and a flexible tube, the rollers exerting pressure upon the flexible tube to forward the liquid contained in said tube when the rotor is rotating.

Such peristaltic pumps are known in the art, for instance from the Swiss patent 562,402. They are used for medical purposes and in the chemical industry, as well as in industrial or semi-industrial laundries for pumping and/or dispensing of liquid products.

These conventional peristatic pumps can be used for delivering variable amounts of liquid product by varying the rotational speed of the rotor. For a number of applications it is desirable, however, to be able to also influence the amount of liquid per unit of time in another way. An example of such an application is for instance a floor cleaning machine equipped with brushes, whereby the amount of liquid cleaning agent per unit of floor area should be kept at a constant value in order to achieve an even result. The amount of product to be delivered should on the one hand be proportional to the rotational speed of the driving wheels, and this may be achieved by coupling the driving motors to the dosing pump, but on the other hand there is a constant factor determined by the type of floor and the amount of soil.

This factor should preferably be operator controllable from the control panel.

We have now found that a variable dosage of liquid product can also be provided by means of the peristaltic pump acoording to the invention, which is chararcterized in that the flexible tube is supported on a separate part of the stator, whereby the distance between said separate part and the rotational axis of the rotor can be continously varied during operation, and the rollers are attached to the rotor by means of flexible arms.

Preferably, the rollers exert pressure upon the walls of the stator.

According to an especially preferred embodiment of the present invention, there is further provided a nonreturn valve in the down stream end of the flexible tube.

The invention will now be further illustrated by means of the following figures, in which a preferred embodiment of a peristaltic pump according to the invention is shown.

Figure 1 is a schematic cross-sectional view of a pump according to the invention, whereby the distance between the separate part of the stator and the rotational axis of the rotor is large, and no liquid is forwarded.

Figure 2 shows a similar cross-sectional view whereby the distance between the separate part of the stator and the rotational axis of the rotor is decreased and liquid is forwarded through the tube.

In Figure 1, the rotor 1 inside the stator 3 rotates in the direction indicated by the arrow. The flexible arms 6 allow the rollers 2 to be in contact with the walls of the stator under a slight pressure. When a roller comes into contact with the flexible tube 4, the latter is squeezed against a separate part 5 of the stator and the passage of liquid is thereby obstructed. In the depicted situation, the squeezed zone is not moved when the rotor is rotated further, because the roller 2 will release the flexible tube upon further rotation. Therefore, no liquid is pumped through the flexible tube.

In Figure 2 the distance between the rotational axis of the rotor 1 is decreased by moving the separate part 5 of the stator 3 closer to the centre. Upon rotating, the squeezed zone in the flexible tube 4 is now created more to the left, and the tube is maintained in a closed situation during a rotation over approximately 60 degrees. During this rotation, liquid product is forwarded from left to right in the flexible tube 4. The dotted roller in Figure 2 illustrates the position where the flexible tube is released again. It will be understood that upon varying the distance between the separate part 5 of the stator supporting the flexible tube, and the rotational axis of the rotor, the position where the obstruction occurs will vary.

Consequently, the amount of liquid product forwarded in the tube will also be varied.

The separate part 5 of the stator may be moved by any suitable means. For instance, there may be provided a screw by which the distance can be manually adjusted during operation. Alternatively, there distance may be varied by means of an electrical motor. Yet another possibility is to attach the separate part 5 of the stator to a lever, by means of which the distance may be varied, either manually or by any other means.

The flexible arms 6 which connect the rollers 2 to the rotor can be made of any suitable flexible plastic material or metal.

Especially in the case when there are only two or three rollers attached to the rotor, is was found to be advantageous to provide a non-return valve in the downstream part of the peristaltic pump according to the invention. Such valves are known in the art and prevent the liquid from flowing back again when the rollers are no longer squeezing the tube.

The peristaltic pump according to the present invention is especially suitable for dosing very small amounts of liquid product, because the flow of product may be finely regulated starting from zero (see Figure 1).

Furthermore, the motor driving the rotor may be running constantly at its optimal speed where an optimal torque is delivered. This is especially an advantage when viscous fluids have to be pumped.

Claims

1. Peristaltic pump comprising a rotor (1) having two or more rollers (2) mounted thereon, a stator (3) and a flexible tube (4), the rollers exerting pressure upon the flexible tube to forward the liquid contained in said tube when the rotor is rotating, characterized in that the flexible tube (4) is supported on a separate part (5) of the stator (3), whereby the distance between said separate part (5) and the rotational axis of the rotor (1) can be continously varied during operation, and the rollers (2) are attached to the rotor (1) by means of flexible arms (6).

2. Peristaltic pump according to Claim 1, wherein the rollers (2) exert pressure upon the walls of the stator (3).

3. Peristaltic pump according to any one of the preceding Claims, further comprising a non-return valve in the down-stream end of the flexible tube (4).