PERISTALTIC PUMP AND METHOD FOR CONTROLLING SUCH A PUMP

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. § 119 to French Patent Application No. 2411398, filed on Oct. 21, 2024, in the French Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety.

TECHNICAL AREA

This invention falls within the technical area of volumetric pumps, and more specifically that of peristaltic pumps with flexible tubes.

This invention also relates to a process for managing such a peristaltic pump.

PREVIOUS TECHNOLOGY

Peristaltic pumps are well known and used in many technical fields, for example the chemical industry, the cosmetics industry, the oil industry, the food industry, and in medicine, in particular for conveying blood or other fluids administered by infusion, . . .

A peristaltic pump consists of a frame to which is fixed a motor whose axis drives a cage consisting of a number of wheels, also called rollers.

These rollers, which move freely on their axis, successively compress a flexible tube until it is airtight.

The alternation of pressure and release on the walls of the flexible tube creates a vacuum and suction so that a fluid trapped between the rollers in the flexible tube is thus pushed along the length of the tube.

A fluid pumped from one open end of the flexible tube, known as the inlet or upstream end, is thus advanced to the other end of the flexible tube, known as the discharge or downstream end.

A main advantage of this peristaltic pump is that the fluid thus displaced remains intact during its transfer since it is not in contact with the rollers at any time but only with the inner wall of the flexible tube.

The peristaltic pump is therefore a particularly healthy pumping solution.

A large majority of peristaltic pumps have a casing with a cylindrical internal face, known as a support face, against which the flexible tube is compressed by the rollers to ensure the airtightness of the tube.

This support can take the form of a metal blade which features a certain elasticity, the said support having a unique predetermined shape.

Alternatively, this support can be made of a plastic material which can be obtained, for example, by molding. An obvious advantage of this type of support is that it is possible to give any desired shape to the inner face of this support against which the flexible tube rests when compressed by the rollers.

However, in peristaltic pumps equipped with such a plastic support, a progressive deformation of the latter is observed over time, a phenomenon known as “creep”.

This creep may have several causes and can, in particular, result from the repeated mechanical actions exerted on the support, during the compressing of the flexible tube, but also from the thermal environment in which the peristaltic pump is immersed when brought into use.

The inside face of the support may then show surface alterations over time, which can lead to a loss of airtightness in the peristaltic pump.

There is therefore a pressing need for a peristaltic pump with a plastic support, the original design of which overcomes the disadvantages of the previous technology described above.

OBJECT OF THE INVENTION

The purpose of this invention is to overcome the disadvantages of the previous technology by proposing a peristaltic pump, simple in its design and in its operating method, whose inner support surface is not affected by creep-related deformation.

Another purpose of this invention is a peristaltic pump of the type described that allows adjustment of the deformation of the intermediate support part, obtained by displacing the lateral arms of the support relative to the main axis of this peristaltic pump.

Another purpose of this invention is a peristaltic pump of the type described that features greater diversity in terms of how it functions.

Another purpose of this invention is a method for managing a peristaltic pump of the type described, allowing to control the deformation of its support for particular requirements.

INVENTION DISCLOSURE

For this purpose, the invention takes the form of a peristaltic pump comprising a casing, a support comprising an inner face and an outer face, said support comprising an intermediate support part from which support arms extend on either side, said intermediate support part being flexible, the inner face of this intermediate support part featuring a semi-cylindrical symmetry around an axis coinciding with the said pump's main axis, said support arms being rigid, the free end of each of the side arms having at least one guide element, said casing having tracks on which these guide elements are able to slide in order to constrain movement of the free ends of the rigid side arms in such a way as to deform the intermediate support part, the radius of its inner face being thus modified while leaving the axis of the intermediate inner face in a position that coincides with the main axis of the said pump.

According to the invention, this support being made of a plastic material, the outer face of said support comprises one or more housings extending in the direction of pumping, at least one of these housings being fitted with an anti-creep device to prevent the deformation of said intermediate support part and/or said casing comprising two parts of the casing body between which said support is placed, said pump shall include at least one anti-creep device connecting said two parts of the casing body by resting on the outer face of the support to prevent deformation of said intermediate support part.

An advantage of the original design of this peristaltic pump is that its optimal operation is ensured by maintaining the original shape of the inner face of the support over time.

When the outer face of the support includes one or more housings for receiving one or more anti-creep devices, it is preferable that these housings are formed by molding the support in plastic.

For example, each housing extends in the pumping direction, not only at the intermediate support part, but also along the rigid support arms referred to as the side arms.

According to one embodiment of this peristaltic pump, the housing(s) take the form of ribs.

An advantage is that these ribs impart a stiffness to the moving support (MS).

According to another embodiment of the peristaltic pump, said or at least one of said anti-creep devices is an elastic spring-forming element.

An advantage is that this elastic element is an open elastic ring which is received in a groove formed in the outer face of the said support.
For example, this open ring is made of spring steel. It features a straight circular cross-section. Alternatively, this spring-forming elastic element could also be flat. For example, it could be a leaf spring.

More generally, this spring-forming elastic element has holding or hanging mechanisms at its ends to ensure that it is held in position in its housing.

This spring-forming elastic element is made of a material that works in elastic deformation such as a spring steel.

According to yet another embodiment of this peristaltic pump, said or at least one of said anti-creep devices is a rigid U-clip resting on the outer face of said support.

More generally, this U-clip must be rigid in the direction of the pump axis (spacing of the casings). In its thickness, it can also be rigid or flexible or have an elastic connection (spring/suspension).
By way of example this U-clip is made of a plastic material.

It is preferable that this U-clip be mounted so that it can be removed, to allow intervention on the support.

As an example, each casing part includes an anchoring element that protrudes from the corresponding casing body to allow locking/unlocking in the U-clip position.

This U-clip connects the two casing parts by covering a portion of the outer surface of the intermediate support part.

The peristaltic pump can thus have one or more elastic elements and/or one or more U-clips.

According to yet another embodiment of this peristaltic pump, it comprises at least one adjustment element to apply an adjustable constraint to the outer face of said intermediate support part and to ensure an adjustment of the deformation of the latter.

Preferably, since this anti-creep device is a U-clip, the said U-clip carries a screw such as a micrometric screw, the free end of which passes through the body of the said U-clip and rests on the outside of the intermediate support part.

Adjusting the position of the screw allows for a variable constraint to be exerted on this outer face of the intermediate support part.

Of course, as an alternative, the U-clip can be without an adjustment element and thus provide a specific constraint.

According to yet another embodiment of the peristaltic pump described, it comprises a rotor that rotates about the pump's said main axis, said peristaltic pump comprising an electric motor for driving said rotating rotor, said electric motor being chosen from among a stepper motor, a direct current motor or an alternating current motor, possibly with an epicycloidal gear train.

According to another embodiment of this peristaltic pump, the moving support to be removable and able to be attached to the casing by simply snapping the guide elements onto the corresponding casing tracks.

The moving support can thus be easily removed to allow for installation or changing of the flexible tube.

According to yet another embodiment of this peristaltic pump, when the lateral U-clip on the outlet side is adjusted by the screw to increase movement of the arm towards a tighter position, the tube is more constrained, which increases the possibility of obtaining a stronger pressure.

According to yet another embodiment of this peristaltic pump, it comprises an electromagnetic actuator, the latter comprising an electromagnet for example, this electromagnetic actuator being configured to automatically generate, when the peristaltic pump is started, a movement of the free end of the single side arm placed on the outlet side, or on the discharge side of the pump, in order to constrain the flexible tube.

Such embodiment advantageously allows the peristaltic pump to withstand high pressures.

By way of illustration only, this electromagnetic actuator can be configured to control the movement of a guide element along at least one track of the single side arm on the outlet side, or on the pump's discharge side, in order to constrain the movement of the free end of the corresponding side arm.

According to yet another embodiment of this peristaltic pump, it comprises at least one flexible, hollow pump conduit, this pump conduit being obtained by molding.

The concept of “molding” here refers to any method of molding, such as low-pressure molding, injection into a mold, etc.

This pump conduit is also referred to as a “molded pump duct”. For example, it can be a molded flexible tube. The peristaltic pump is then designed to pump fluids through this molded flexible tube, or obtained by molding.

One advantage is that such a hollow pump conduit, obtained by molding, offers a large number of possibilities for designing the peristaltic pump. For example, the molding of the hollow conduit makes it possible to confer specific properties to this conduit such as different thickness ratios, particularly at its inlet and outlet, and/or to give it a particular shape, such as conical.

Such a conical shape of the hollow conduit makes it possible to play with the pressure, for example that of the fluid displaced by the peristaltic pump.

It also makes it possible to hold this conduit in position when the pump is in operation, for example when the latter comes to a stop against a means of holding the moving support.

According to yet another embodiment of this peristaltic pump, it comprises at least one hollow, flexible pump conduit, this pump conduit having an inlet, or suction side, and an outlet, or discharge side, this pump duct having different thickness ratios between its inlet and its outlet.

It is preferable that the thickness ratio of the hollow duct at its outlet is greater than the thickness ratio of the hollow duct at its entrance.

It will be remembered that the thickness ratio (e/Dint) of a peristaltic pump conduit, i.e., the ability of the duct to maintain, or contain, pressures, is the ratio between the thickness of the wall of the hollow duct (e) and the duct's inside diameter (Dint).

For purely illustrative purposes, the duct could thus have 5×3 (D_ext×D_int) at the pump's inlet and, at the outlet, 3×0.5, and the moving support could include a housing to accommodate the extra thickness of the duct on the outlet or discharge side. This results in a thickness ratio of 5 at the outlet, with the pump then able to withstand high pressures.

This invention also relates to a method for managing a peristaltic pump as described above, with an adjustment element that exerts a constraint on the outer face of the intermediate support part resulting in two portions of the intermediate support part on either side of this adjustment element, the guide element(s) placed at the free end of only one of the rigid side arms of said support is/are slid along the length of the corresponding traces of the casing to deform the corresponding portion of the intermediate support part while leaving the other rigid support arm fixed, thereby to leaving the other portion of the intermediate support part unchanged.

Of course, this displacement of only one of the side support arms can be carried out on both the intake and discharge side of the peristaltic pump.

The adjustment element is thus arranged to exert a constraint on the outer face of the intermediate support part, resulting in two independent portions of the intermediate support part, on either side of this adjustment element.

For example, this adjustment element can be a U-clip and/or the free end of a screw such as a micrometric screw, carried on this U-clip.

For illustrative purposes only, it will be understood that since the free end of a screw locally constrains the intermediate support part, the deformation of a portion of this intermediate support part, placed on one side of the free end of the screw in the direction of pumping, by the displacement of the corresponding side support arm, does not propagate to the other portion of the intermediate support part placed on the other side of the free end of the screw.

According to one embodiment of this method for managing a peristaltic pump, the adjustment element is placed at the top of said peristaltic pump to create two approximately equal portions of the intermediate support on either side of this regulating element.

According to another embodiment of this method for managing a peristaltic pump, on detecting a vacuum on the inlet side of the said pump, the guide element(s) placed at the free end of the single rigid side arm, placed at the inlet of the pump, i.e., on the inlet side, is/are slid in such a way as to remove the airtightness of the portion of the flexible tube placed on the inlet side, when it is compressed by the rollers of the pump, for the duration of this vacuum.

According to yet another embodiment of this method for managing a peristaltic pump, the guide element(s) placed at the free end of the single rigid side arm, placed on the side of the peristaltic pump's outlet, i.e., on the discharge side, is/are made to slide in order to maintain a higher pressure.

This makes it possible to increase the pressure on the outlet side of the peristaltic pump.

According to yet another embodiment of this method for managing a peristaltic pump, the said flexible tube is chosen in advance so that its hardness is higher or lower than the range of anticipated hardness values to ensure the nominal airtightness of the said pump.

By way of example, since the hardness of the tube is greater than the maximum hardness value provided by the manufacturer to ensure the pump's nominal airtightness rating, this flexible tube exerts a counterforce allowing an adjustment of the pressure applied to the flexible tube.

This invention also relates to a computer-readable medium comprising a set of software instructions which, when executed by a processor, make it possible to implement some of the steps of the process for managing a peristaltic pump as described above.

Of course, the term “computer” means any programmable device.

Alternatively, it could also be a computer program that could be downloaded from a communications network and/or recorded on a machine-readable medium and/or that can be executed by a processor such as a processor installed in said peristaltic pump, the movement of the micrometric screw and/or the ends of said rigid side arms along the tracks being motorized.

In addition, the moving support (MS) contemplated in the invention has the advantage of allowing the use of flexible tubes of different diameters. It adapts naturally to the flexible tube mounted on the peristaltic pump.

More generally, this invention also relates to a peristaltic pump comprising at least one hollow, flexible pump conduit, this pump conduit being obtained by molding.

The concept of “molding” here refers to any method of molding, such as low-pressure molding, injection into a mold, etc.

The advantage of such a hollow duct obtained by molding is that it offers a large number of possibilities for designing the peristaltic pump. For example, the molding of the hollow conduit makes it possible to confer specific properties to this conduit such as different thickness ratios, particularly at its inlet and outlet, and/or to give it a particular shape, such as conical.

Such a conical shape of the hollow conduit makes it possible to play with the pressure, for example that of the fluid displaced by the peristaltic pump.

It also makes it possible to hold this conduit in position when the pump is in operation, for example when the latter comes to a stop against a means of holding the moving support.

This hollow conduit can thus be conical for the whole of its length.

By way of illustration only, it comprises at least one hollow, flexible pump conduit, this pump conduit comprising an inlet, or suction side, and an outlet, or discharge side, and the pump conduit having different thickness ratios between its inlet and outlet.

It is preferable that the thickness ratio of the hollow duct at its outlet is greater than the thickness ratio of the hollow duct at its entrance.

It will be remembered that the thickness ratio (e/Dint) of a peristaltic pump conduit, i.e., the ability of the duct to maintain, or contain, pressures, is the ratio between the thickness of the wall of the hollow duct (e) and the duct's inside diameter (Dint).

For purely illustrative purposes, the duct could thus have 5×3 (D_ext×D_int) at the pump's inlet and, at the outlet, 3×0.5, and the moving support could include a housing to accommodate the extra thickness of the duct on the outlet or discharge side.

This results in a thickness ratio of 5 at the outlet, with the pump then able to withstand high pressures.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages, aims and special features of this invention will be apparent from the following description which, for explanatory purposes, while not being in an way of a limiting nature, is provided with regard to the attached drawings, in which:

FIG. 1 is a schematic representation of a peristaltic pump according to a first embodiment of this invention;

FIG. 2 is an enlarged, partial view of the peristaltic pump in FIG. 1, showing the top of this pump with the positioning of the U-clip and the micrometric screw;

FIG. 3 is a plan view of the peristaltic pump in FIG. 1, showing the support received between the two parts of the casing body, the elastic open ring housed in a groove of the outer support surface and the U-clip and its micrometric screw;

FIG. 4 is a view from below and a perspective view of the peristaltic pump support in FIG. 1;

FIG. 5 is a schematic representation of a peristaltic pump according to a second embodiment of this invention;

DESCRIPTION OF THE EMBODIMENTS

The drawings and the description below essentially contain elements of a certain nature. They can therefore serve not only to improve the understanding of this invention, but can also contribute to its definition, as required.

First of all, it is noted that the figures are not to scale.

FIGS. 1 to 4 are a schematic illustration of a peristaltic pump 10 according to a first embodiment of this invention.

This peristaltic pump 10 comprises a casing 11, which is made up of two parts of the casing body which are combined and together create space to receive a moving support 12. These parts of the casing body 11 are obtained here by molding them in a plastic material.

It also includes a flexible tube (not shown) for conveying a liquid. This flexible tube is made of an elastomer material.

The peristaltic pump 10 has a rotor that carries three freely rotating rollers, the turning of the rotor being driven by an epicycloidal gear train motor (not shown). These rollers are evenly distributed around the periphery of the rotor, so that each roller is spaced at an angle of 120° from its neighbor.

The inner face of the moving support 12 forms a base against which the flexible tube is compressed by the rollers to ensure the tube's airtightness and to ensure the movement of the liquid received in it.

This moving support 12, made from a single piece of a plastic material, thus comprises an inner face 13 and an outer face, an intermediate support part from which rigid support arms 14 and 15 extend on either side of it.

When the moving support 12 is in position on the peristaltic pump's frame, these rigid support arms 14, 15 are placed laterally to a main axis of the pump determined by the motor shaft so that these support arms 14, 15 are usually referred to as “side support arms”.

These side support arms 14 and 15 are straight here, but they could of course take any other shape such as an angled form, in particular for the purpose of taking into account the space available in the pump frame.

Because this intermediate support part is flexible, the inner face 13 of this intermediate support part has a semi-cylindrical symmetry around an axis that coincides with the pump's main axis.

The free end of each of these side support arms 14, 15 has bosses 16 that extend laterally from them, and are capable of sliding along corresponding guide tracks 17 provided on the casing body 11.

The displacements of the free ends of the side support arms 14 and 15 along these upstream and downstream guide tracks 17 are thus constrained, and the intermediate support part is deformed. In particular, the radius of its inner face 13 of moving support 12 is modified while leaving the axis of the intermediate inner face 13 coinciding with the peristaltic pump's main axis 10.

The outer face of the moving support 12 has grooves 18 extending in the direction of pumping in one of which is placed an open elastic ring 19 which rests on the moving support 12 not only at its intermediate part but also on part of the side support arms 14, 15. This open elastic ring 19 is made of spring steel.

The peristaltic pump 10 also comprises a U-clip 20 carrying a micrometric screw 21, the rod of which can pass through the body of the U-clip so that the free end of this screw is placed in a position that projects from the inside face of the U-clip 20. This U-clip/screw assembly is arranged at the top of the peristaltic pump.

The body of the U-clip 20 features a U-shape whose arms are angled so that the ends of the U-clip 20 engage with protruding parts 22 formed on the outer faces of the two body parts of the casing 11 for locking in the U-clip in position.

The underside of the U-clip 20, which spans the space separating the two parts of the body of the casing 11 in which the moving support 12 is placed, thus rests on the outer face of the intermediate support part, also having the effect of constraining the latter.

The function of the U-clip 20 and of the open elastic ring 19 is to prevent deformation of the intermediate support part in order to preserve the airtightness of the flexible tube when compressed by the rotor rollers.

In addition, the free end of the micrometric screw 21 can be moved to advantage so that it rests on the outer face of the intermediate support part and, by additional movements, to enable a precise adjustment, or even further adjustment of the constraint applied to this outer face of the intermediate support part.

Thus, not only can the inner surface of the intermediate support part be deformed by the movement of the ends of the side support arms 14, 15 along the upstream and downstream tracks 17 of the casing, but it can also be deformed in a finer way, by moving the micrometric screw 21 towards the main axis of the peristaltic pump.

FIG. 5 is a schematic representation of a peristaltic pump 50 according to a second embodiment of this invention;

The elements of the peristaltic pump 50 shown in FIG. 5, and bearing the same references as those shown in FIGS. 1 to 4, represent the same objects, which will not be described again below.

The peristaltic pump 50 in FIG. 5 differ from that illustrated in FIGS. 1 to 4 in that it has two U-clip/screw assemblies 20, 21 mounted on the casing at the ends of the side support arms 14, 15 to act directly on these side arms.

The adjustment of the constraint applied by each of these assemblies on the moving support makes it possible to decouple the support arms 14, 15 upstream and downstream, or on the inlet and discharge sides, to manage the airtightness differently between the inlet and discharge ends of the peristaltic pump 50.