MANAGING METHOD

Abstract

A method for managing a pumping device (10) suitable, in use, to supply in a periodic pulsed manner a plurality of given quantities (Q) of a given fluid (M) so as to generate a flow of said given fluid (M) presenting a first given average flow rate (PM1); the supply of each given quantity (Q) being both preceded and followed by respective first pauses (P1) in the supply of the given fluid (M) presenting a first given duration (T1); the method in question comprising at least a phase of stopping the pumping device (10) so as to introduce at least a given second pause during the supply of at least a quantity (Q) of the given fluid (M).

Description

The present invention relates to a managing method. In particular, the present invention relates to a method for managing a pumping device. In more detail, the present invention relates to a managing method, which can be used to adjust the flow of a fluid supplied through a pumping device.

BACKGROUND TO THE INVENTION

The use of peristaltic pumps is well known in many sectors whenever it is necessary to pump a fluid maintaining it insulated inside a respective pumping circuit, so as to avoid the fluid entering into contact with the outside environment, thus preventing contaminations. Peristaltic pumps are widely used for example in the food industry and in the hospital sector where it is necessary, for hygienic reasons, to pump fluids under conditions of high cleanliness or even under controlled atmosphere and/or in sterile environment.

As it is well known, a peristaltic pump is provided with a highly elastic flexible tube, made typically of natural rubber, Hypalon or polypropylene, which is peripherally compressed by at least one mechanical pressing member, for example a roller, which occludes the lumen of the tube. Each of these pressing members, in use, is made slide longitudinally along the tube so that the “squeeze” generated by it displaces in a concordant and continuous manner along the tube and pushes the fluid, contained inside the pumping circuit, in the same sliding direction as the rollers. In more detail, there are various types of peristaltic pumps: for example, in the medical sector linear peristaltic pumps are commonly used, wherein a flexible tube is arranged linearly and is engaged in sequence and in a periodic manner by a plurality of rotating and coaxial cam members, identical to each other and reciprocally synchronised. Alternatively, the rotary peristaltic pumps are well known, which are characterised by compactness and great sturdiness. This type of pumps provides for the use of a stator unit, which presents a first central cylindrical seat housing a respective rotor provided peripherally with a plurality of rollers. The stator unit furthermore presents a second seat, that is substantially semi-toroidal, to house stably an elastic tube, which is therefore folded along at least an arc of a circle concentric with the axis of rotation of the rotor holding the rollers. These rollers, in use, peripherally push the tube, thus generating squeezes thereof which, in use, slide longitudinally and cyclically along the tube in a concordant manner as the rotation of the rotor.

Independently of the respective type, each peristaltic pump is suitable to supply each respective fluid pumped by it in a periodic pulsed, and thus inevitably discontinuous, manner. Actually, the presence of each squeeze, which causes the pumped fluid to move forwards, causes inevitably a stop, or at least a sudden reduction, and therefore a discontinuity, in the supplied fluid and this discontinuity will occur periodically whenever the squeeze passes at the inlet of the delivery duct of the pump.

The presence of these discontinuities in the supply flow of a peristaltic pump represents a great disadvantage for the use of these devices when it is necessary to pump a fluid with a very low flow rate, for example in the order of 1 ml/min, corresponding to a regime of rotation lower than 5 rpm. It should be noted, in fact, that in order to supply reduced flow rates of fluid, the sliding speed of the pressing members along the tube is usually minimised, and this entails that the duration of each stop/discontinuity in the supply is prolonged, with the result that the supplied flow is not substantially uniform but, on the contrary, it presents significant non-uniformities. In this regard it should be noted that the American firm Abbott Laboratories is the holder of the patent U.S. Pat. No. 5,219,279 relating to a volumetric pump and to an operative method thereof, which allows to supply a flow rate of fluid which can be defined substantially at will by the user. In particular, this volumetric pump comprises a gear motor, which actuates a pumping device provided to engage the flexible tube, transporting the fluid to be pumped, with a respective cam member.

This pumping device is designed so that 24 rotations of the gear motor correspond to each pumping cycle, in order to allow a fine adjustment of the position of the cam member engaging the tube. At this point it should be noted that the document U.S. Pat. No. 5,219,279 specifies that it is possible to adjust, substantially at will, the average flow rate of the supplied fluid by varying the speed of the gear motor and inserting a given number of pauses of given duration during the pumping cycles of the cam member; however, as clearly shown in FIG. 22 of the mentioned document, the supplied fluid, although presenting the desired average flow rate, is not uniform, but on the contrary it alternates a first phase, wherein the supply of fluid is greatly pulsed, with a second phase, wherein the supply is substantially continuous. It should be furthermore noted that, in order to obtain such a fine adjustment of the average flow rate of supplied fluid, the volumetric pump in question comprises a more complex and more expensive pumping device, which requires more maintenance than the common rotary peristaltic pumps.

Alternatively, the American firm Baxter International Inc is holder of the international patent application WO96/01371, describing and claiming a peristaltic pumping system for medical applications, suitable to supply a fluid with a flow rate which can vary between a maximum of 170 ml/min and a minimum value lower than 10 ml/min. At this end, the pumping system comprises a rotary peristaltic pump provided with a motor with variable rotational speed, and with a control device, suitable to control an alternate actuation of the respective rotor so as to introduce slowdowns or pauses in the supply, aimed at reducing the average flow rate of the pumped fluid. This pumping system therefore allows to supply fluid with a reduced average flow rate which can be defined at will, but, on the other hand, it is not suitable to overcome the drawbacks due to the discontinuity of the flow of supplied fluid. In particular, the teachings of the document WO96/01371 are based upon the approximation that the fluid supplied by the respective pumping system is continuous when the rotor works with a constant angular speed. Consequently, this document takes only the average flow rate of the peristaltic pump into consideration, and not the presence of the pauses of the supplying phase, which are intrinsic to the peristaltic structure of the pumping system. Therefore, the insertion of pauses during each supplying phase, even though it allows reducing the average flow rate of the supplied fluid, amplifies the non-uniformity of the flow of fluid supplied by the rotary peristaltic pump. It should be furthermore noted that the method for managing the pumping system described in the document WO96/01371 provides:

• • a fixed number of pauses/slowdowns for each pumping cycle;
  • that by varying the desired average flow rate of supply, the duration of the phase of effective supply varies substantially in inverse proportion to the duration of the pauses/slowdowns in supply. It is therefore readily apparent that, when extremely reduced average flow rates are chosen, the flow supplied by the pumping system according to the document WO96/01371 will present high discontinuities, as short periods of effective supply are followed by long periods of pause/reduction in the supply.

Moreover, a known alternative solution to increase the uniformity of a flow supplied by a rotary peristaltic pump is that of increasing the number of rollers carried by the respective rotor; this solution however entails higher production and maintenance costs, and is therefore excessively expensive for the largest part of the sectors wherein the rotary peristaltic pumps are commonly used.

Therefore, in view of the above description, the problem of managing a peristaltic pumping device so that it is suitable to supply continuously and substantially uniformly flows of reduced flow rate, definable at will, is currently unsolved and represents an interesting challenge for the applicant, that aims at obtaining a managing method which can be implemented on a simple and economical peristaltic pumping device and which is suitable to solve the above illustrated problems.

SUMMARY OF THE PRESENT INVENTION

The present invention relates to a managing method. In particular, the present invention relates to a method for managing a pumping device. In more detail, the present invention relates to a managing method which can be used to adjust the flow of a fluid supplied through a pumping device.

The object of the present invention is to provide a method which can be validly used to manage a pumping device preferably of the peristaltic type; this method allows to solve the above illustrated drawbacks, and it is therefore suitable to satisfy a plurality of requirements that to date have still not been addressed and therefore suitable to represent a new and original source of economic interest, capable of modifying the current market of the pumping devices.

According to the present invention, a managing method is provided, whose main characteristics will be described in at least one of the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

Further characteristics and advantages of the managing method according to the present invention will be more apparent from the description below, set forth with reference to the accompanying drawings and diagrams, which illustrate at least one non-limiting example of embodiment, in which identical or corresponding phases of the method are identified by the same reference numbers. In particular:

FIG. 1 is a schematic perspective view of a pumping device suitable to implement a managing method according to the present invention;

FIG. 2 illustrates diagrams relating to the supply of fluid through the pumping device of FIG. 1, functioning according to a first operating mode;

FIG. 3 illustrates diagrams relating to the supply of fluid through the pumping device of FIG. 1, functioning according to a second operating mode;

FIG. 4 illustrates diagrams relating to the supply of fluid through the pumping device of FIG. 1, functioning according to a third operating mode; and

FIG. 5 illustrates diagrams relating to the supply of fluid through the pumping device of FIG. 1, functioning according to a variant of the third operating mode of FIG. 4.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In FIG. 1, number 1 indicates, in its entirety, a pumping device 10 comprising a pump 15 provided with an inlet duct 11, which can be used to supply a fluid M to the pump 15, and an outlet duct 12, through which each pumped portion of fluid M is supplied. It should been noted that hereinafter the term fluid M will indicate not only a liquid or a gas, but any type of flowable substance, i.e. any type of substance which presents macroscopically viscosity features substantially equivalent to those of a fluid and which can be therefore easily transported through a duct or a tube.

In particular, as illustrated in FIG. 1, the pump 15 preferably comprises a peristaltic pump suitable to supply the fluid M from the outlet duct 12 in a pulsed manner, i.e. through an intermittent and periodic supply of given quantities (jets) of fluid M alternated with respective pauses in the supply. In fact, as it is well known, the previously illustrated functioning principle upon which the peristaltic pumps are based intrinsically entails the presence of at least first pauses P1 in the supply of the fluid M, caused by the passage of a squeeze of the tube associated with a respective pressing member, at the entrance of the outlet duct 12.

In particular, with reference to FIG. 1, it should be noted that hereinafter reference will be made to a peristaltic pump 15 of the rotary type provided with a stator unit 16 housing an elastic tube 17 and with a rotor 18 provided with at least a pressing roller 19. The rotor is carried into rotation by an actuator, known and therefore not illustrated, for example a DC electric motor or a brushless motor, so as to be suitable to rotate with a given and constant angular speed V, which hereinafter will be considered fixed for the sake of simplicity.

In use, when the rotor 18 rotates continuously at this angular speed V, the pumping device 10 will be suitable to supply the fluid M with a flow rate, whose time dependence, and therefore the dependence from the angular position a of the rotor 18, is illustrated in FIG. 2a. From this FIG. 2a it is clearly understood that, when the pumping device 10 operates according to this first operating mode A, wherein the rotor 18 rotates continuously at a constant angular speed V, the flow rate of the supplied fluid M is pulsed and periodic. In more detail, to each complete rotation, or cycle, of the rotor 18, a number of supply periods T corresponds, equal to the number of the rollers 19 carried by the rotor 18. In this regard it should be specified that hereinafter the term supply period T will indicate the time period comprised between the end of two first pauses P1. Therefore, with reference to the preferred embodiment of FIG. 1, the pump 15 will be preferably provided with two rollers 19 peripherally carried in diametrically opposite positions, and it will therefore present a rotation cycle equal to two supply periods T.

With reference to FIG. 2 again, each period T will correspond to the sum of the duration TQ of a phase of supply at a constant flow rate PC of a quantity Q of the fluid M, and the duration T1 of a first pause P1. It is furthermore clearly apparent that, even if pulsed, the flow of the fluid M, supplied by the pumping device 10 functioning in the first operating mode A, presents a first average flow rate PM1 equal to the ration between the quantity Q and the duration of the period T and clearly lower than the constant flow rate PC.

Now, with reference to FIG. 2b, it is possible to note that the fluid M supplied by the pumping device 10 growths over time (and relative to the angular position a of the rotor 18) according to a substantially stepped graph presenting a height which is a whole multiple of the quantity Q wherein each “plateau” represents a first pause P1.

With reference to FIG. 1, the pumping device 10 comprises a control unit 20 electrically connected to the actuator associated with the rotor 18 so as to be suitable, in use, to control actuations of this rotor 18 and to monitor, second by second, the angular position a of the rotor 10. In particular, this control unit 20 comprises a CPU 25 of the programmable type and it is provided with a memory 21 and with an interface 22, through which a user can select operating modes for the pumping device 10 and/or insert the value to be assigned to parameters of supply. Alternatively, if the pumping device 10 is part of a more wide apparatus, this interface can be connected to a computer, suitable to perform a program for supervising the supply of the fluid M and, therefore, enabled to control the operation of the pumping device 10.

In particular, the memory 21 stores the numerical values of a function, which associates the flow of the fluid M, which can be supplied in use by the pumping device 10, with an independent variable such as, for example, the pumping/rotation time of the rotor 18 or the angular position a of the rotor 18. Just by way of example again, the memory 21 can preferably, but without limitation, contain the numerical data of the function illustrated in FIG. 2a and the control unit 20 will be therefore enabled to calculate easily the values of the function illustrated in FIG. 2b by means of simple operations of numerical integration. In other words, as the memory 21 contains information about the flow rate of the pumping device 10, the control unit 20 is suitable to calculate the precise quantity of supplied fluid M as a function of the pumping/rotation time of the rotor 18 and/or of the angular shift described by the rotor 18.

Therefore, thanks to this feature of the control unit 20, the pumping device 10 is suitable to work according to an operating mode B, wherein doses Q′, definable substantially at will, of fluid M are supplied in an intermittent manner. In more detail and with particular reference to FIG. 3, when the pumping device 10 operates in this second operating mode B, the control unit 20 puts the rotor 18 into rotation exactly for the time necessary to supply a dose Q′ and, at this point, stops the rotation of the rotor 18 and waits for a time interval of duration T2, which can be defined substantially at will by the user through the interface 22. Therefore, when functioning in the second operating mode B, the pumping device 10 is suitable to supply doses Q′ alternated with second pauses P2 in supply having duration T2.

With particular reference to FIGS. 2 and 3 again, it should be noted that the data contained in the memory 21 allow to take into account also the presence of the first supply pauses P1 and therefore, contrarily to what occurs in the prior art, the pumping device 10 is suitable to supply in a repeatable manner a plurality of doses Q′ of fluid M substantially identical to each other. Clearly, in the particular case in which the end of the supply of a dose Q′ corresponds to the end of the supply of a quantity Q, and therefore to the beginning of a first pause P, the rotor 18 will continue its run for a time interval of duration T1 and it will then stop for a time interval presenting a duration substantially identical to the difference between the duration T2 and the duration T1 so that, in this case, the first pause P1 is overlapped with the respective second pause P2.

In any case, the control unit 20 calculates the exact angular position of stopping of the rotor 18 to obtain each required dose Q′ and it is therefore suitable to synchronise the chronological arrangement of each second pause P2 relative to at least one first pause P1 so as to supply doses Q′ precisely. This feature of the pumping device 10 is particularly useful when one desires to supply first doses Q′ reduced relative to the quantity Q as, in the pumps designed according to the prior art, these reduced doses are subjected to high uncertainties in supply and non-uniformities due to the presence of the first supply pause P1.

At this point, with reference to FIG. 4, it should be noted that the pumping device 10 is suitable to operate also according to a third operative mode C, wherein the fluid M is supplied in a substantially uniform manner with a second average flow rate PM2 which is lower than the first average flow rate PM1 and which can be defined substantially at will by the user. In particular, to enable this third operative mode C, the control unit 20 controls an alternate actuation of the rotor 18, wherein this rotor 18 is repeatedly actuated for a time interval of duration TQ″ and subsequently stopped for a time interval of duration T3. In other words, as it is clear apparent from FIG. 4a, the third operative mode C of the pumping device is based upon the introduction of a given number of third pauses P3 in the rotation of the rotor 18 during the supply of each quantity Q, which is therefore subdivided in a discrete number of fractions Q″.

At this point, it should be noted that the third operative mode C is significantly different from what seen in the prior art, wherein the rotor of the peristaltic pump is brought to a respective minimum angular speed and, for each period, once the quantity Q has been completely supplied, this rotor is stopped for a given time interval, so that the supplied average flow rate corresponds to the value set by the user. However, in this operative mode, which is typical of the prior art, long supply phases alternate with long pauses, and therefore the flow of supplied fluid is significantly non-uniform.

Vice versa, in the managing method according to the present invention, when the pumping device 10 operates according to the third operative mode C, the rotor 18 is alternatively stopped and brought to the angular speed V for a plurality of times during the supply of each quantity Q of fluid M, thus obtaining a supplied flow which is substantially uniform over time.

In particular, it should be noted that, based upon the flow rate set by the user, the control device 20 will determine the number and the duration T3 of the third pauses P3, which shall be inserted during the supply of each quantity Q of fluid. As it is clearly apparent from FIG. 4 again, the control device 20 is designed so as to select a given number of third pauses P3 according to the required flow rate and in such a manner that all these third pauses P3 present a same duration T3 substantially of the same order of magnitude of the duration T1 of the first pauses P1. In fact, as the angular speed V is constant, the duration T1 of the first pauses P1 is fixed and it is connected with the intrinsic structural features of the pump 15, whilst the duration of each third pause P3 is controlled by the control unit 20 and is connected both with the flow rate chosen by the user and by the number of third pauses P3 inserted in each supply period T comprised between the end of two consecutive first pauses P1. At this point, with reference to FIG. 4 again, it should be noted that the third pauses P3 are distributed during each supply period T in a substantially uniform manner between the end of a first pause P1 and the beginning of the subsequent first pause P1; more in particular, each group of third pauses P3 inserted during the supply of a quantity Q of fluid M results synchronised relative to the pair of consecutive first pauses Pl, which chronologically delimit the supply of this quantity Q, in such a manner that the flow of supplied fluid M, even though it result “microscopically” pulsed, presents a flow rate which is substantially uniform over time, independently of the value chosen by the user for this flow rate.

In this regard, it should be specified that, in order to maximise the uniformity over time of the flow of supplied fluid M, the control unit 20 is programmed so as to select a given number N of third pauses P3 to be introduced during the supply of each quantity Q based upon the value of the average flow rate PM2 assigned by the user. In particular, the control unit 20 is preferably enabled to select the given number N among a plurality of whole values, preset during the programming phase, so that to each value of the second average flow rate PM2 assigned by the user, a unique whole value can be associated, preset for the given number N. At this end, it is possible to subdivide all the values which can be assigned to the second flow rate PM2, i.e. all the values of flow rate comprised between zero and the first average flow rate PM1, in a discrete plurality of intervals, or fields, of flow rate, mathematically contiguous to each other, and to associate to each of these fields a preset whole value which can be assigned to the given number N. In use, once a value has been assigned to the second average flow rate PM2, the control unit 20 will identify the field containing this second average flow rate PM2 and will assign the respective preset whole value to the given number N.

At this point, once the given number N of third pauses P3, associated with the supply of each quantity Q, has been defined, the control unit 20 will calculate the duration of the supply time intervals TQ″ and the durations T3 of the third pauses P3. With reference to FIG. 4, it is clear that N+1 phases of supplying a fraction Q″ will correspond to N third pauses P3 for each supply of a quantity Q, and therefore the durations T3 and TQ″ can be calculated, for instance, according to the following formulas:

$\hspace{1em}\begin{array}{c}{\mathrm{TQ}}^{″}=\frac{\mathrm{TQ}}{N+1}\\ T3=\frac{\mathrm{PM}2/Q-\mathrm{TQ}-T}{N}\end{array}$

Anyway, independently of the algorithms used to calculate the durations T3 and TQ″, it should be noted that, during the phase of programming the control unit 20, each preset whole value has been associated to a respective flow rate field, so that the durations T1, TQ″ and T3 present substantially identical values or anyway values of the same order of magnitude, in order to maximise the uniformity over time of the flow of supplied fluid M.

Alternatively, instead of associating a preset whole value for each flow rate field, it is possible to give to the control unit 20 the task of calculating, every time, a given number N based upon the value of the second average flow rate PM2 inserted by the user. In this case, the choice of N could be made, for example, through an algorithm of maximisation of the uniformity over time of the flow rate of the flow of supplied fluid M; this algorithm can be implemented, for example but without limitation, by means of a numerical procedure of minimisation of the sum of the square numbers of the differences between T3 and TQ″ relative to T1.

At this point, it would be advisable to note that the pumping device 10, when it operates according to the third operative mode C, is suitable to supply a flow of fluid M, which simulates the flow which can be supplied by a rotary peristaltic device provided with N+1 rollers. As it is well known, the greater the number of rollers carried by the rotor is, the greater the uniformity of the supplied flow is, but with higher costs for producing and managing the peristaltic pumping device.

Therefore, thanks to the managing method illustrated above, a simple pumping device 10 provided with an economical rotary peristaltic pump 15 provided with a limited number of rollers and suitable to operate only with a fixed and non-adjustable angular speed of the rotor, can be used to supply continuously flows of fluid M with high uniformity and flow rate which can be set by the user substantially at will, thus simulating the behaviour of pumping devices provided with a greater number of rollers and with more expensive actuators with adjustable speed.

Lastly, it should be noted a further difference between the third operative mode C of the method according to the present invention and the prior art. In the prior art, to obtain a supply of the fluid M with particularly reduced flow rates, attempts have been made to minimise the speed of actuation of the pump 15/of the rotor 18, thus obtaining a supplied flow non-uniform over time. Vice versa, the managing method according to the present invention allows to maximise the uniformity over time of the flow of supplied fluid M by increasing the angular speed V of the rotor 18 and it is therefore possible to state that the method has been designed based upon a project trend opposite to that upon which the prior art is based. In fact, as it can be noted from FIGS. 2 and 4, by increasing the angular speed V it is possible to minimise each duration T1 and consequently also the durations T3 and TQ″, which are calculated by the control unit 20 so as to be substantially identical to T1. Therefore, in order to obtain a same given flow rate PM2 when the angular speed V increases, it will be sufficient to increase the given number N of third pauses P3 and, consequently, a flow will be supplied, in which the third pauses P3 and the phases of supplying the fractions Q″ alternate with a greater frequency. Lastly, it is apparent by observing FIG. 4 that a flow supplied by the pumping device 10 will be the more uniform the greater the given number N of third pauses P3, and therefore the greater the frequency with which these third pauses P3 alternate with the phases of supplying a fraction Q″ of fluid M.

It should be however noted that in practice, in order to carry the rotor 18 into rotation, it could be economically advantageous to use actuators provided with limited mechanical characteristics, and therefore unsuitable to perform a series of stops and subsequent (re)-actuations at high frequency.

In this case, alternatively to what described above, it could be impossible to insert a high number N of third pauses P3 during the supply of each quantity Q and therefore, in order to supply a flow presenting a reduced second flow rate PM2, it is possible to define a reduced number N of third pauses P3 presenting a respective duration greater than the duration T1. In more detail, with particular reference to FIG. 5, it should be noted that it is possible to supply a flow presenting a reduced second flow rate PM2 by reducing the given number N of third pauses P comprised between each two first consecutive pauses P1 and simultaneously by elongating the durations T3 and TQ″ so that they present substantially an equal value greater than the duration T1 of each first pause P1. In particular, with reference to FIG. 5 again, it should be noted that, in order to guarantee the uniformity of the supplied flow, it is necessary that each first pause P1 is followed by a fourth pause P4 of stopping the rotation of the rotor 18 presenting a fourth duration T4 substantially equal to the difference between the third duration T3 and the first duration T1, so that the sum of the first and fourth durations T1 and T4 of each first and fourth pause P1 and P4 is substantially equivalent to the duration T3 of each third pause P3.

In any case, in view of the above description and independently of the variant of the third operative mode C implemented by means of the pumping device 10, the method according to the present invention is a method for managing a peristaltic pumping device 10 which can be implemented by means of a programmable control unit 20, provided with a user interface 22 and suitable to control the actuation of this pumping device.

This method can be schematised as follows: first of all, the method according to the present invention comprises a phase of selecting, through of the interface 22, an operative mode for the pumping device 10. In particular, a user can select the first operative mode A when he/she desires to pump the fluid M in a continuous manner and at the maximum flow rate which can be obtained with the pumping device 10, or the second operative mode B, when he/she desires to supply given doses Q′ at regular intervals, or, lastly, he/she can select the third operative mode C, when he/she desires to obtain the supply of the fluid M with a reduced flow rate which can be defined substantially at will, and in a manner substantially uniform over time.

In the first case, the phase of selecting an operative mode is followed by a phase of actuating the pumping device for an indeterminate period of time, which will prosecute until the user or a supervision program for supervising the control unit 20 will send a stop command. Clearly, this phase of actuating the pumping device 10 will comprise a phase of actuating the rotor 18 into rotation with a constant angular speed V for a substantially undetermined period of time.

Moreover, in the case in which the second operative mode B is selected, the phase of selecting the operative mode will be followed by a phase of assigning a value for the doses Q′ and, as the case may be, a phase of assigning a value for the duration T2 of each second pause P2 interposed between the supply of two consecutive doses Q′. At this point, the control unit 20, before supplying each dose Q′, will perform a phase of calculating the given angle, by which the rotor 18 must rotate so that the pumping device 10 will supply a quantity of fluid equal to the respective dose Q′. It is clear that this phase of calculating the given angle of rotation of the rotor 18 is performed by the rotor 18 based upon the data contained in the memory 21 and it can comprise, for instance, a phase of integrating numerically a function that expresses the flow rate of the pump 15 as a function of the angular position a of rotation of the rotor 18, and a phase of inverting the integrated function obtained. It should be noted that, as the angular speed V of the rotor 18 is constant, each width of the angle of rotation of the rotor 18 is equivalent to a given period of rotation and therefore the phase of calculating the given angle, by which the rotor 18 shall rotate, is equivalent to a phase of calculating a duration TQ′ for each time interval for which the rotor 18 must rotate so that the pumping device 10 supplies a respective quantity of fluid equal to a dose Q′. In this regard and with reference to FIG. 3, it should be noted that, due to the presence of the first pauses P1, the duration TQ′ of each phase of supplying a dose Q′ is generally variable and therefore it should be each time calculated by the control unit 20 based upon the data contained in the memory 21.

At this point, following each phase of calculating a duration TQ′, the method according to the present invention comprises a phase of actuating the pumping device 10/the pump 15 for a time interval of this duration TQ′, followed by a phase of stopping the supply of the fluid M for a time interval of duration T2. This phase of stopping the supply of the fluid M will comprise, according to the cases, a phase of stopping the pumping device 10/the pump 15 for a time interval of duration T2 or a phase of actuating the pumping device 10/the pump 15 for a time interval of duration T1 followed by a phase of stopping the pumping device 10/the pump 15 for a time interval of duration T4 substantially identical to the difference between the duration T2 and the duration T1.

In particular, the three subsequent phases of calculating a duration TQ′, of actuating the pumping device 10/the pump 15 for a time interval of duration TQ′ and of stopping the pumping device 10/the pump 15 for a time interval of duration T2 can be repeated cyclically and in this order for a substantially undetermined time, so as to enable a continuous supply of doses Q′ substantially identical to each other, until a user or a program for managing the control unit 20 sends a stop command.

Lastly, if the user selects the third operative mode C, the phase of selecting an operative mode will be followed by a phase of assigning a value for the desired second average flow rate PM2 of supply. This phase of assigning a second average flow rate PM2 will be therefore followed by a phase of selecting the given number N of third pauses P3, which will chronologically subdivide the supply of each quantity Q into N+1 supplies of a fraction Q″. It should be noted that this phase of selecting a given number N of third pauses P3 can comprise a phase of associating a preset whole value to the given number N according to the value of the second average flow rate PM2, in order to maximise the uniformity over time of the flow of supplied fluid M. Alternatively, this phase of selecting a given number N of third pauses P3 can comprise a phase of calculating this given number N by means, for example, of a given numerical algorithm of maximisation of the uniformity over time of the flow rate of the flow of fluid M supplied by the pumping device 10.

At this point, once the control unit 20 has selected/calculated the given number N, the method according to the present invention provides for a phase of calculating the durations T3 and TQ″, so that the second average flow rate PM2 resulting for the supplied flow matches the value selected by the user. This phase of calculating the durations T3 and TQ″ can comprise preferably a phase of calculating numerically the result of the two formulas F1 and F2 illustrated above.

At this point a phase can be performed of supplying the fluid M in a manner pulsed and presenting a substantially uniform second average flow rate PM2. This phase comprises a phase of synchronising N+1 supply intervals of duration TQ″ and N third pauses P3 during each period comprised between the end of a first pause P1 and the start of the subsequent first phase P1. These N+1 intervals of duration TQ″ and these N pauses shall be therefore distributed in a uniform manner between each two consecutive first pauses P1 and at this end the phase of synchronising presents the following steps in sequence:

• • a phase of actuating the pumping device 10/the pump 15 for a time interval of duration TQ″;
  • a cyclic repetition, for a given number N of times, of a phase of stopping the pumping device 10/the pump 15 for a time interval of duration T3 and of a phase of actuating the pumping device 10/the pump 15 for a time interval of duration TQ″; and
  • a phase of actuating the pumping device 10/the pump 15 for a time interval of duration T1.

Alternatively, if the second variant of the third operative mode C is used, characterised by a reduced given number N of third pauses P3, the initial phase of actuating the pumping device 10/the pump 15 for a time interval of duration TQ″ is immediately followed by a respective phase of stopping the pumping device 10/the pump 15 for a time interval of duration T4.

Briefly, the result of this synchronisation phase is that illustrated in FIG. 4 or 5, and consists in supplying a fluid M in a manner substantially uniform over time independently of the value selected by the user for the second average flow rate PM2. At the same time, this synchronisation phase allows to prevent third pauses P3 from overlapping by mistake first pauses P1, thus causing non-uniformities in the supplied flow, similarly to what occurs in the illustrated prior art.

The managing method according to the present invention for managing the peristaltic pumping device 10 is clearly apparent from the description above and does not require further explanations. However, it could be advisable to note that the choice of using a rotary peristaltic pump 15 is merely by way of example, and does not limit the generality of the managing method according to the present invention. In fact, the managing method according to the present invention can be validly applied to all the pumping devices wherein the supplied flow presents a periodic character similar or substantially equivalent to that illustrated in FIG. 2.

Lastly, in view of the above description, it is clearly apparent that the managing method according to the present invention is suitable to solve the technical problem in question, and it is therefore suitable to manage a peristaltic pumping device, so that this latter is suitable to supply in a continuous and substantially uniform manner flows of reduced flow rate which can be defined at will.

Claims

1. A method for managing a pumping device (10) of the peristaltic rotary type provided with a rotor (18) and suitable, in use, when said rotor (18) rotates with a constant angular speed (V), to supply in a periodic pulsed manner a plurality of given quantities (Q) of a given fluid (M) in such a way so as to generate a flow of said given fluid (M) presenting a first given average flow rate (PM1); the supply of each said given quantity (Q) being both preceded and followed by respective first pauses (P1) in the supply of said given fluid (M) presenting a first given duration (T1); said managing method comprising at least a phase of stopping said pumping device (10) so as to introduce at least a given second pause (P3) during the supply of at least a said quantity (Q) of said given fluid (M); each said phase of stopping said pumping device (10) comprising a phase of synchronising each said given second pause (P3) relative to at least a corresponding said first pause (P1) in the supply of said given fluid (M); said phase of synchronising each said second pause (P3) being performable in an automatic manner through control means (20) for controlling said pumping device (10); characterised in that each said phase of stopping said pumping device (10) is both preceded and followed by a phase of supplying a given fraction (Q″) of said quantity (Q) of said given fluid (M); each said phase of supplying a given fraction (Q″) presenting a given second duration (TQ″).

2. A method according to claim 1, characterised by comprising a phase of selecting a given number (N) of said second pauses (P3) interposed between each two consecutive said first pauses (P1) and suitable to fractionate the supply of each said quantity (Q) of fluid (M); each said second pause (P3) being associated with a respective phase of stopping said pumping device (10) and presenting a given third duration (T3) in such a way so that the flow of said given fluid (M) supplied by said pumping device (10) presents at least a second average flow rate (PM2) lower than said first average flow rate (PM1) and definable substantially at will.

3. A method according to claim 2, characterised in that each supply of a said quantity (Q) of said given fluid (M) is carried out through a number of said phases of supplying a said given fraction (Q″) equal to said given number (N) increased by one unit.

4. A method according to claim 2, characterised in that said given number (N) can be chosen, in use, among a plurality of preset whole values so as to maximise the uniformity over time of the flow rate of the flow of fluid (M) supplied by said pumping device (10).

5. A method according to claim 2, characterised in that said phase of selecting a given number (N) comprises a phase of calculating said selected number (N) by means of a numerical algorithm suitable to maximise the uniformity over time of the flow rate of the flow of said given fluid (M) supplied by said pumping device (10).

6. A method according to claim 5, characterised in that said numerical algorithm is implemented by means of a numerical procedure of minimisation of the sum of the square number of the difference between said third duration (T3) and said first duration (T1), with the square number of the difference between said second duration (TQ″) and said first duration (T1).

7. A method according to claims 2, characterised in that said phase of selecting a given number (N) is followed by a phase of calculating said third duration (T3) of each said second pause (P3) and said second duration (TQ″) of each said phase of supplying a said fraction (Q″) of said quantity (Q) in such a way so that the flow of said given fluid (M) supplied by said pumping device (10) presents said second average flow rate (PM2).

8. A method according to claim 1, characterised in that said phase of synchronising each said second pause (P3) comprises, following each said first pause (P1), the performance in sequence of a phase of actuating said pumping device (10) for a time interval presenting said second duration (TQ″); a cyclical repetition for a said given number (N) of times of a phase of stopping said pumping device (10) for a time interval presenting said third duration (T3) and of a phase of actuating said pumping device (10) for a time interval presenting said second duration (TQ″); and a phase of actuating said pumping device (10) for a time interval presenting said first duration (T1).

9. A method according to claim 1, characterised in that said phase of synchronising each said second pause (P3) comprises, following each said first pause (P1), the performance in sequence of a phase of stopping said pumping device (10) for a time interval presenting a fourth duration (T4) substantially equal to the difference between said third duration (T3) and said first duration (T1); a phase of actuating said pumping device (10) for a time interval presenting said second duration (TQ″);

a cyclical repetition for a said given number (N) of times of a phase of stopping said pumping device (10) for a time interval presenting said third duration (T3) and of a phase of actuating said pumping device (10) for a time interval presenting said second duration (TQ″); and a phase of actuating said pumping device (10) for a time interval presenting said first duration (T1).

10. A method according to claim 1, characterised by being suitable to simulate the supply of a flow of said given fluid (M) by a pumping device (10) provided with a rotary peristaltic pump (15) equipped with a number of respective pressing rollers (19) equal to said given number (N) increased by one unit.

11. A method according to claim 1, characterised in that each phase of actuating said pumping device (10) consists of a phase of actuating said rotor (18) into rotation at a given constant angular speed (V).

12. A method according to claim 1, characterised by comprising an initial phase of selecting an operative mode of said pumping device (10) among at least a first operative mode (B), in which said pumping system (10) is suitable to supply said given fluid (M) in a plurality of doses (Q′) substantially identical to each other and definable substantially at will, and a second operative mode (C), in which said pumping system (10) is suitable to supply continuously a flow (F) of said fluid (M) presenting a flow rate definable substantially at will and substantially uniform over time.

13. A method according to claim 12, characterised in that said phase of selecting the operative mode of said pumping device (10) is followed by a phase of assigning a value definable substantially at will to said second average flow rate (PM2) of the flow of said given fluid (M) to be supplied through said pumping device (10); said second average flow rate (PM2) being lower than said first average flow rate (PM1).