EP0840854B1 - Peristaltic pump - Google Patents

Description

The present invention relates to improvements made to peristaltic pumps, especially those involved in irrigation devices and suction of physiological fluids, with regulation automatic flow and pressure.

The evolution of diagnostic endoscopy towards surgical endoscopy induced new constraints, which devices must meet and instruments used. The irrigators and medical aspirators belong to this category of materials.

Originally designed to expand the seat cavity of observation and then used more recently to create dynamically an "aseptic operating space", these devices had to adapt their characteristics to the means therapies implemented by surgeons endoscopists, means that require rapid reactions to ensure patient safety.

Peristaltic pumps, including a tube flexible transfer pinched successively by rollers describing one behind the other a closed circuit, in particular rollers carried by a rotor, are of use frequent for the transfer and pressurization of aggressive or sterile liquids (see for example document CH-A-433 992.) Whatever their shape and number of their rollers, pumps current peristaltics do not require, at a time whatever their functioning, that two rollers simultaneously active. The enclosed space inside of the pump tube and delimited by these two rollers constitutes the liquid transfer chamber.

Peristaltic pumps are the type of pump preferred in medical applications, in particular in extracorporeal circulation devices or in the irrigation systems of the cavities seat of a surgical intervention, such as urology or arthroscopy, where these pumps are already in use currently. As an example of a medical device known using a peristaltic pump, we can here cite the surgical irrigation and suction apparatus described in documents FR-A-2642297 and WO-A-9008562. However, the peristaltic pumps available on the market generally deliver a cyclical flow, presenting instantaneous variations in flow that can exceed 20 to 30% of the average flow of these pumps. This is illustrated schematically by the diagram in Figure 1, where the time t is plotted on the abscissa, and the flow D in ordered.

These variations in flow are the consequence of variations in the volume of the transfer chambers during pebble release phases and also, more accessory, compression of the transfer tube exerted by said rollers. Such variations in flow can be a serious drawback in applications manufacturers of peristaltic pumps are committed to designing regulating devices or shock absorbers, placed at the pump outlet. These devices, most often passive, are generally only effective only for a given beat frequency, so for a restricted operating range.

Document US-A-3726613 proposes, with a view to the elimination of cyclic flow variations of a pump peristaltic, an "active" device comprising an organ pressure, acting in a time-varying manner on the transfer tube at the pump outlet, under the control of an actuating device which itself comprises a cam integral with the pump rotor, and acting by means of an oscillating lever on the organ presser. This document contains an exact analysis of physical phenomena and the problem posed but it describes a solution which, using "active" elements, is mechanically quite complex, and relatively expensive.

By document DE-U-9412228, we also know a peristaltic pump which claims to regulate the flow of exit thanks to a hollow area of continuous width increasing, between the rotor and the stator, from the input up to the pump outlet, in the direction defined by the displacement of the rollers. This configuration results from a eccentric arrangement of the circular recess of the stator, relative to the axis of the rotor.

However, the document under consideration does not explain the the whole mode of operation of the device in question, and the proposed solution does not appear satisfactory either in its principle, nor in its results. At the very least, the operation of this device seems related to the simultaneous cooperation of a large number of pebbles from the rotor with the tube, which implies "embedding" deep of the rotor in the stator, resulting in difficulty in quickly and completely removing the rotor relative to the stator.

The present invention aims to eliminate these disadvantages, providing a peristaltic pump improved, as described in claim 1, provided with an integrated device for flow regulation, automatically compensating for variations this in a simple, economical way by manufacturing and efficient, according to a principle of reliable and precise operation, and with a configuration allowing easy separation and speed of the rotor relative to the stator, for the purpose of security and interchangeability.

• d'une part, à répartir la variation du volume de la chambre de transfert sur un angle égal à l'angle séparant deux galets consécutifs ;
• d'autre part, à compenser la non-linéarité de la variation du volume de la chambre de transfert, par rapport à la hauteur de levée du galet en cours d'échappement, ce qui constitue un avantage appréciable par rapport au document DE-U-9412228 précité ;
• enfin, à compenser l'effet de compression des galets sur le tube de transfert du liquide.

To this end, in the peristaltic pump which is the subject of the invention, of the type comprising a fixed body or stator and a rotor provided with rollers at its periphery, between which passes a flexible liquid transfer tube pinched by at least two consecutive rollers between which is defined a transfer chamber, it is provided, to make the output flow of the pump substantially constant, that its fixed body or stator comprises, following a hollowed out area of substantially constant radius and centered on the axis of the rotor, where the transfer tube is pinched by the rollers, an area of progressively increasing radius, this radius being measured relative to the axis of the rotor. Preferably, the region of progressively increasing radius extends over an angle substantially equal to the angle separating two consecutive rollers on the pump rotor. This provision covers:

• on the one hand, to distribute the variation in the volume of the transfer chamber over an angle equal to the angle separating two consecutive rollers;
• on the other hand, to compensate for the non-linearity of the variation in the volume of the transfer chamber, relative to the lifting height of the roller during exhaust, which constitutes an appreciable advantage compared to the document DE-U -9412228 cited above;
• finally, to compensate for the compression effect of the rollers on the liquid transfer tube.

The profile to give to the stator, in the area particular considered, must therefore be a function of rotor rollers diameter, tube characteristics transfer used (inside and outside diameters, hardness), and the pressure exerted by the rollers on the transfer tube, that is to say the crushing of this tube.

To explain the above, the diagram of the figure 2 represents the variation of the volume V of a room transfer according to the pinch P of the tube. The axis of abscissa represents pinch P in mm; the value P = 0 corresponds to the contact of the roller on the tube without pinching, the value P = 5 corresponds to the occlusion of the tube, and the value P = 5.5 corresponds to the compression of 0.5 mm from the walls of the tube, produced after occlusion. The axis ordinates represents, in percentage, the variation of volume of a transfer chamber under the effect of pinching exerted by a roller, in other words, the volume occupied by this roller inside the transfer tube. In this example, it is more particularly the action of a roller with a diameter of 16 mm on a tube in silicone with an outside diameter of 8 mm and a inner diameter of 5 mm, the roller realizing during the complete action compression of the tube walls 0.5 mm. In the free part, i.e. before complete occlusion of the tube, the curve C of variation of the volume V relative to the height of the roller takes a form approximately parabolic. The shape given to the stator in the area of gradually increasing radius takes into account counts the intrinsic characteristics of the tube system transfer / roller, shown in Figure 2, to make the volume change proportional to the angular variation. The variation to be spread over 30 °, pinches are determined from the diagram of figure 2 so that 1 ° of angular variation corresponds to 3.33% change in volume. The Rays thus defined allow the shape of the stator to be determined of the pump, projected onto an orthonormal plane, as illustrated in Figure 3 where the x-axis x represents a line tangent to the rotor, the position x = 0 corresponding to the middle position, i.e. the plane containing the axis of the rotor, while the y-axis represents the digging of the stator (the values indicated being expressed in millimeters). More generally, the variation of the radius is a function, determined experimentally, in which the angle intervenes, the diameter of the transfer tube, the diameter of the rollers and the prestress applied to the tube in the area of constant radius. The previous example is repeated below, with numerical data concerning the values of rays.

To help avoid flow variations at the pump outlet, it is also recommended to plan a relatively large diameter rotor, carrying relatively numerous rollers, the rotor having a practically "tangential" arrangement relative to the pump stator. This provision, limiting the curvature of the stator in the zone of action of the rollers, is particularly advantageous, not only for limit flow variations, but still so as to facilitate quick release of the pump head by simple recoil of the rotor or stator, which allows to provide an additional level of security. In particular, the pump rotor can be mounted on a carriage driven by a jack, allowing quick release in the radial direction, in particular in the event of overpressure not under control. The "tangential" arrangement also allows design the stator as a removable and easily interchangeable, in particular a part forming part part of a single-use tubing, and the characteristics are related to this tubing, which has its importance in medical applications and surgical.

Overall, the device that is the subject of the invention provides particularly simple and economical, at the outlet of the pump, flow and pressure variations which can be ± 2% compared to the nominal values.

Figure 4 est une vue de face, partiellement en coupe, d'une pompe péristaltique selon la présente invention ;

Figure 5 est une vue en perspective d'un appareil comportant application de la pompe péristaltique de figure 4 ;

Figure 6 est une vue en perspective du stator de cette pompe péristaltique, conçu comme une pièce amovible.

In any case, the invention will be better understood with the aid of the description which follows, with reference to the appended diagrammatic drawing representing, by way of example, an embodiment of this peristaltic pump:

Figure 4 is a front view, partially in section, of a peristaltic pump according to the present invention;

Figure 5 is a perspective view of an apparatus comprising application of the peristaltic pump of Figure 4;

Figure 6 is a perspective view of the stator of this peristaltic pump, designed as a removable part.

Figure 4 very schematically shows a pump peristaltic, which includes a flexible transfer tube 1, a fixed body or stator 2 and a rotor 3 of general shape cylindrical, mounted rotating around an axis 4 orthogonal to the direction of the tube 1. The stator 2 here has a recess 5 of particular profile, specified below.

The rotor 3 carries, at its periphery, a plurality rollers 6 distributed at regular angular intervals, for example twelve rollers 6 separated from each other by angular intervals of 30 °. In a certain area from their circular trajectory, the rollers 6 come pinch the transfer tube 1, pressing it against the bottom of recess 5 of stator 2. Between two rollers 6 pinching the tube 1 has a zone convex 7 forming liquid transfer chamber, at least two rollers 6 being simultaneously active at an instant any in the area of constant radius and delimiting thus a transfer chamber closed to its two extremities.

The recess 5 of the stator 2 mainly extends along an arc, so with a constant radius, in being centered on the axis 4 of the rotor 3. However, this recess 5 has a particular profile in an area 5a located on the side of the liquid outlet, area which extends over an angle at least equal to the angle separating the rollers 6 (30 ° in the example given).

Thus, relative to the axis 4 of the rotor 3, the bottom of the recess 5 comprises, in the area considered, radii R1, R2, R3, .. Rn progressively increasing. The useful cross-section of the liquid is therefore increasing downstream, which compensates for the variation in volume observed during the escape of a roller 6, so as to obtain a flow of liquid D practically constant at the pump outlet.

R1 = 74,50 mm

R2 = 75,18 mm

R3 = 75,69 mm

R4 = 76,25 mm

R5 = 76,85 mm

R6 = 77,90 mm

R7 = 80,00 mm

   pour un rayon nominal de 74,50 mm, dans une pompe dont le rotor 3 a un diamètre hors tout de 144 mm, et comporte des galets 6 ayant un diamètre de 16 mm et disposés tous de 30°, le tube de transfert 1 en silicone possédant un diamètre extérieur de 8 mm et un diamètre intérieur de 5 mm, et la compression des parois de ce tube 1 dans la zone de rayon constant étant de 0,5 mm.For example, the recommended radii R1, R2, R3, etc., measured every 5 ° in an area extending over a total angle of 30 °, can be as follows:

R1 = 74.50 mm

R2 = 75.18 mm

R3 = 75.69 mm

R4 = 76.25 mm

R5 = 76.85 mm

R6 = 77.90 mm

R7 = 80.00 mm

for a nominal radius of 74.50 mm, in a pump whose rotor 3 has an overall diameter of 144 mm, and includes rollers 6 having a diameter of 16 mm and all arranged at 30 °, the transfer tube 1 in silicone having an outside diameter of 8 mm and an inside diameter of 5 mm, and the compression of the walls of this tube 1 in the zone of constant radius being 0.5 mm.

As still shown in FIG. 4, the rotor 3 of the peristaltic pump can be quickly removed from the stator 2, in the radial direction as indicated by an arrow F, thus releasing the transfer tube 1, in particular in the event of uncontrolled overpressure. To this end, the rotor 3 is mounted on a carriage driven by a jack, not shown.

In Figure 5 is shown a unit of fluid management for endoscopic surgery, involving the application of a peristaltic pump such as previously described, designated as a whole by the item 8, whose stator 2 and rotor 3 appear partially. The stator 2 is here designed as a part molded removable, shown alone in Figure 6, which is an integral part of sterile tubing 1 for use unique. This stator 2, removable and interchangeable, is mounted on a support 9, itself fixed on the front of the device.

As shown more particularly in Figure 6, stator 2 has in particular a profiled groove 5.5a receiving the zone of the tubing 1 called to cooperate with the rollers carried by the rotor 3, the longitudinal profile of the groove 5, 5a corresponding to the definition given previously. At both ends of this groove are formed of eyelets, respectively of inlet 10 and outlet 11, crossed by the pipe 1 and ensuring the maintaining this on the stator 2. The stator 2 presents here again another groove or surface 12, straight receiving a part of tubing which does not cooperate with the rotor 3.

The stator 2 has, on its face opposite to grooves 5,5a and 12, a dovetail conformation 13, which cooperates with a complementary conformation provided on the fixed support 9. The removable mounting of the stator 2 is performed by cooperation of these conformations in dovetail, the extraction of stator 2 being done in the direction indicated by the arrow G in the figure 5.

Claims (4)

1. A peristaltic pump of the type having a fixed body or stator (2) and a rotor (3) provided on its periphery with rollers (6) between which passes a flexible liquid-transfer tube (1) pinched by at least two succeeding rollers (6) between which is defined a transfer chamber (7) and wherein, in order to make the flow at the outlet (D) of the pump fairly uniform, its fixed body or stator (2) has at the end of a recess (5) of constant radius of curvature centered on the axis (4) of the rotor (3), where the transfer tube (1) is pinched by the rollers (6), an outlet region (5a) of progressively increasing radius (R1, R2... Rn), this radius being measured to the axis (4) of the rotor (3), the outlet region (5a) of progressively increasing radius (R1, R2... Rn) extending over an angle generally equal to the angle separating two consecutive rollers (6) on the rotor (3), characterised in that in the outlet region (5a) of progressively increasing radius (R1, R2... Rn) the variation of the radius is a function of the angle such that the variation of the volume of the transfer chamber (7) is proportion to the angular variation, the profile given to the stator (2) to that end in said region (5a) being a function of the characteristics of the transfert tube (1) and of the squashing of this tube (1), and in that the rotor (3) of the pump is of large diameter and carries a large number of rollers (6), said rotor (3) being mounted practically "tangentially" with respect to the stator (2) of this pump.
2. The peristaltic pump according to claim 1, characterised in that its rotor (3) is fixed on a carrier displaced by a fluid-powered cylinder to permit rapid disengagement in the radial direction (arrow F).
3. The peristaltic pump according to claim 1 or 2, characterised in that its stator (2) is designed as a detachable and interchangeable piece, in particular a piece forming an integral part of a single-use tube (1).
4. The peristaltic pump according to claim 3, characterised in that the detachable stator (2) has a dove-tail formation (13) fitting with a complementary formation on a fixed support (9).

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