Patent Description:
The need to accurately measure certain quantities of fluids to be inserted into special containers such as bottles, vials, ampoules and the like has long been known, in the pharmaceutical, cosmetic and food fields.

Various systems have therefore been developed for measuring fluids, which in specific uses can be chosen according to the chemical-physical characteristics of the fluid, the precision requirements of the measuring, the extent of the measuring volumes, the risk class of the measured fluids and the sterility requirements of the sector of use.

A first type is that of systems that use peristaltic pumps.

The peristaltic pumps generally comprise a flexible tube, in which the fluid is contained, arranged around a rotor member having a plurality of peripherally distributed pressing members, adapted to locally engage the tube, thus causing it to squeeze. The rotation of the pressing members determines the advance of said squeezing and therefore the feeding of a measured amount of fluid contained in the tube. An example of this type of measuring devices is described in European patent <CIT>.

A problem encountered in the use of peristaltic pumps is the risk that the tube collapses due to the continuous stresses by the pressure members, thus preventing the correct passage of the fluid and compromising the accuracy of the measurement. In addition, peristaltic pumps do not allow high prevalence, therefore they are not suitable for measuring particularly dense fluids.

A second type of known measuring devices uses piston volumetric pumps which, on the other hand, are suitable for measuring dense and viscous liquids. Such measuring devices comprise a piston member inserted into a chamber and reciprocated along an axis to draw in and dispense a defined volume of fluid. An example of this type of measuring devices is disclosed in European patent <CIT>.

A problem encountered in the use of this type of measuring device is the risk of scale, which can form especially when measuring products containing sugars or particularly dense pastes. Such encrustations may prevent the correct passage of the fluid through the dispensing duct, and may also affect the accurate measurement of the fluid.

A third type of known measuring devices is the so-called "time/pressure" measuring systems, based on the ratio of some variables such as for example the pressure impressed on the fluid and the opening time of the delivery valve present in the system. Such systems typically comprise an electronic control device for managing the time of opening of the dispensing valve and the measuring pressure.

"Time/pressure" systems may have problems in maintaining measuring accuracy and precision, due to the inertia of the checks involved.

Finally, there are flowmeter measuring systems, particularly suitable for measuring large volumes of fluid. Such systems generally consist of a pump that provides a fluid flow rate at a pressure regulated by an electronic control device. Also for this type of measuring systems the problem of the accuracy and precision of the measuring arises.

Furthermore, in known systems, in general, the problem of contact between fluid and mechanical parts arises. For example, in the presence of particular chemical-physical characteristics, such contact may cause damage to the mechanical parts hit by the fluid or pose a risk to the operator or the maintenance technician.

Application <CIT> discloses, as a further example of a solution, a valve system for dispensing a product in the form of an aerosol. Such system comprises a measuring container arranged inside a rigid container and provided with elastic means for exerting a compressive action on the same measuring container, so as to dispense a measured amount of fluid.

The present invention aims at solving the mentioned problems by devising a fluid measuring device, capable of operating with high precision and accuracy.

It is a further object of the present invention to provide a versatile measuring device, suitable for measuring fluids with different chemical-physical characteristics.

Another object of the invention is to provide a measuring device that enables the measurement of fluids under optimal sterile conditions.

Another object of the invention is to provide a measuring device that enables the measurement of even dangerous fluids reducing the risk of damage to the mechanical components involved, as well as the risk of contamination of the environment in contact with the operator or the maintenance technician.

A still further object of the invention is to provide a measuring device for fluids of simple constructive and functional conception, which is certain in operation, versatile, as well as relatively inexpensive.

The foregoing objects are achieved, according to the present invention, by the measuring device of claim <NUM>.

The measuring device according to the invention comprises a central body provided with a connection portion for the connection to at least one suction duct and to at least one duct for delivering the fluid, a gas or a liquid, and a containment portion defining an internal cavity for a clearance volume of fluid and comprising a plurality of openings for the passage of the fluid outside the same containment portion.

The measuring device further comprises a casing mounted externally to the containment portion so as to define between the same casing and the containment portion an external chamber adapted to contain a measuring volume of the fluid.

The measuring device then comprises an elastic body fitted externally to the containment portion and retained for an annular portion between the central body and the casing, the elastic body being expandable for the rest between a first rest configuration, in which the same elastic body adheres to the containment portion and a second expanded configuration, at which the elastic body is expanded until it occupies the measuring volume of the external chamber, by effect of a flow of fluid through said openings.

The casing of the measuring device usefully has a duct for feeding a contrast fluid upon expansion of the elastic body.

The duct is preferably made on a bottom of the casing.

The elastic body, preferably made of elastomer, acts as a separating and pumping element, sucking inside the volume made available by the external chamber and ejecting the measuring volume from it.

According to a feature of the invention, the provision of the external chamber, with the respective measuring volume, guarantees a precise cyclical and repetitive measurement.

Furthermore, it should be noted that the elastic body, fitted on the containment portion of the central body, also serves as a protection for the casing, in particular for the external chamber, as it shields from contact with the fluid to be measured. Therefore, the surrounding environment is safe and the cleaning and sterilization are extremely easy.

Another advantage of the measuring device according to the invention lies in the fact that the fluid is not subjected to heating by the pumping action of the elastic body. Therefore, the measuring device avoids the formation of undesired encrustations, possible for example in the presence of sugary fluids when heated.

The measuring device may also be easily adjusted. In fact, it is possible to adjust the insertion of the containment portion inside the outer chamber, or to adjust the positioning of the bottom of the casing, in case the latter is made as a separate element. This allows a very precise micro-adjustment of the measuring volume, defined by the external chamber.

According to an even autonomous aspect, applicable to measuring devices of different type, the containment portion can be advantageously divided into a suction section and a delivery section, such that the fluid to be measured cannot flow from one to the other directly. In practice, the above sections are separate.

Preferably, to achieve such separation, the suction section and the delivery section are separated by an intermediate section, inserted inside the inner chamber preferably by interposing sealing means.

The suction section is preferably provided with respective suction openings, adapted to allow the passage of the fluid to be dispensed from the inner chamber to the outside of the containment body following the expansion of the elastic body.

The delivery section is preferably provided with respective delivery openings, adapted to allow the return of the fluid to be delivered from the outside of the containment body to the internal chamber following the return of the elastic body to the rest configuration.

According to an aspect that may be also autonomous, also applicable to other types of measuring devices, a valve element can be provided, movable alternatively between an open configuration, at which it is distant from the suction openings, to allow the passage of fluid from the suction outside the containment portion, in a suction step, and a closed configuration, at which the valve element is approached to the suction openings, so as to obstruct them, to allow the passage of the fluid measuring volume sucked in and collected outside the containment portion, in a delivery step, through the delivery openings only.

The valve element may be made of elastic material, impermeable to the fluid to be measured.

The provision of the valve element is advantageous in the transitional, opening and closing steps of the shut-off devices present in the supply and dispensation circuits of the fluid to be measured.

According to an aspect that may be also autonomous, applicable as well to other types of measuring devices, a filtering element can be provided, to precisely regulate the flow rate of the fluid to be measured. In this way the measuring device can be easily adjusted.

The filter element can be arranged at delivery openings made at the delivery section.

The filter element is preferably made of a tubular band of mesh material.

According to an advantageous aspect, applicable as well to measuring devices of another type, the elastic body can be made of a tubular element, having an end closed by a joint.

The joint can be easily made of a welded end edge.

The elastic body can be assembled inside the casing, so as to be retained on an outer wall of the containment portion, as well as at said annular portion, also at a second annular portion, so as to segregate the expansion of the elastic body between the annular portion and the second annular portion, to define the measuring volume.

The elastic body can be advantageously inserted inside said duct for feeding said contrast fluid, thus being retained by a respective internal wall in an expansion phase.

The duct is preferably provided with internal grooving to allow inflow and/or outflow of the contrast fluid to the external chamber and/or therefrom.

The measuring device may therefore also be easily adjusted. In fact, for this purpose it is possible to regulate the inflow and/or outflow of contrast fluid, air and/or nitrogen for example, to the external chamber. This feature allows a very precise micro-adjustment of the flow rate of the measuring fluid, thanks to the controlled expansion of the elastic body.

Finally, the combined action of the contrast fluid and the filter element allows a very precise adjustment of the flow rate of the measuring fluid.

Finally, it is provided that the measuring device may be used in a "disposable" manner, for example by making the casing of plastic and packaging the same measuring device in a kit further comprising the flexible tubing connecting to a measuring machine and to a respective containment tank of the fluid to be measured. The kit may usefully be supplied inside a sterile package.

The details of the invention will become more apparent from the detailed description of a preferred embodiment of the fluid measuring device according to the invention, illustrated as a non limitative example in the accompanying drawings, in which:.

With particular reference to these figures, an apparatus for measuring fluids, gases or liquids, is indicated as a whole with the reference <NUM>, which employs the measuring device <NUM> according to the invention. The fluids to be measured may in particular be intended for use in the pharmaceutical sector, but also in other industrial sectors, for example in the food and cosmetic sector.

The apparatus <NUM> comprises a tank <NUM> for containing the fluid to be measured, gas or liquid, the measuring device <NUM>, a dispensing unit <NUM>, and a measuring circuit <NUM>, configured to connect the tank <NUM> to the dispensing unit <NUM> through the measuring device <NUM>.

The storage tank <NUM> is adapted to contain the fluid to be measured at a first pressure value P<NUM>. The first pressure value P<NUM> can be maintained within the tank <NUM> by controlled injection of an inert gas, preferably nitrogen. The fluid is also preferably maintained at a certain level of filling of the tank <NUM>, for example by employing means for controlling the supply of fluid to the tank <NUM>.

The dispensing unit <NUM> may comprise at least one dispensing nozzle <NUM> or an equivalent means, which allows the dispensing of measured quantities of fluid, in order to fill correspondingly respective containment units, for example in the form of bottles, vials, ampoules or the like.

Preferably the dispensing unit <NUM> comprises a plurality of dispensing nozzles <NUM>, so as to feed simultaneously or according to a certain sequence a plurality of containment units, for the benefit of the productivity of the system in which the measuring apparatus <NUM> is inserted.

The measuring circuit <NUM> comprises at least one suction duct <NUM> connecting the tank <NUM> to the measuring device <NUM> and at least one delivery duct <NUM> connecting the measuring device <NUM> to the dispensing unit <NUM>. The suction duct <NUM> and the delivery duct <NUM> are preferably of a flexible type, for example of silicone material, suitable for use, among others, in both the food and pharmaceutical sectors.

The apparatus <NUM> further comprises a first shut-off device <NUM> arranged on the suction duct <NUM> and a second shut-off device <NUM> arranged on the delivery duct <NUM>. The first shut-off device <NUM> and/or the second shut-off device <NUM>, which are adapted to adjust the opening of the ducts on which they are installed, are preferably made by means of a crush valve of known type.

The measuring device <NUM> is adapted to supply the dispensing unit <NUM> through the delivery duct <NUM> with a dosing volume VDOS of fluid, sucking it through the suction duct <NUM>.

The measuring device <NUM> comprises a central body <NUM>, an elastic body <NUM> and a casing <NUM> (see <FIG>), preferably developed along a longitudinal axis A.

The central body <NUM> is made of a material suitable for contact with the fluid to be measured, for example metal, preferably stainless steel. Furthermore, the central body <NUM> is made of a material not deformable under the conditions of use for measuring the fluid of interest, for example of a rigid material.

The central body <NUM> has a connecting portion 11a, a fluid containing portion 11b and a locking portion 11c.

The connection portion 11a comprises at least one tubular coupling <NUM> for the passage of the incoming and/or outgoing fluid. More precisely, the connection portion 11a allows connection to the measuring circuit <NUM>, in particular to the suction duct <NUM> and to the delivery duct <NUM>, for example through suitable connection means.

In the case shown for example in <FIG>, the connecting portion 11a comprises a single coupling <NUM>, useful both for entry and for exit of the fluid, preferably along the aforementioned longitudinal axis A. The connection means can therefore provide a fitting, that is a single tubular connection that leads to a bifurcation, shaped like a Y, for connection to both the suction duct <NUM> and the delivery duct <NUM>. This fitting may possibly be made integrated with the suction and delivery ducts <NUM>, <NUM>. Alternatively, it is possible to provide that the connecting portion 11a shapes at least a pair of couplings <NUM>, for example a first coupling for the injection of fluid and a second coupling preferably flanked to the first, for the exit of the same fluid. In this case, the suction duct <NUM> and the delivery duct <NUM> can also be directly connected to the aforementioned couplings.

The containment portion 11b encloses an internal containment chamber <NUM> which, in use, is in communication with the measurement circuit <NUM> through the coupling <NUM> of the connection portion 11a. Said internal chamber <NUM> defines a containment volume VN which represents in operation a "clearance volume".

The containment portion 11b is preferably made of a tubular cartridge <NUM>, for example cylindrically shaped, comprising a plurality of openings <NUM>, preferably evenly distributed on the side wall around the longitudinal axis A.

The openings <NUM> can be made by respective perforations, for example of circular shape. Alternatively, the cartridge <NUM> can be made of a suitably shaped mesh around the longitudinal axis A, such that said openings <NUM> are defined between respective strands of the mesh.

The cartridge <NUM> can form an open base (see in particular <FIG>) and in this case the inner chamber <NUM> is in any case delimited by the elastic body <NUM> in a rest condition, as described in detail below.

The locking portion 11c may further form a hooking element <NUM>, for example a flange, for attaching to the casing <NUM>, as described in detail below. For example, the hooking element <NUM> may extend between the connecting portion 11a and the containing portion 11b, transversely to the longitudinal axis A.

The elastic body <NUM> is made of a membrane <NUM> of elastic material, for example of elastomer, shaped like a sleeve or sheath, to cover the cartridge <NUM>. The elastic body <NUM> is then fitted externally to the cartridge <NUM>, so as to engage its external surface. In particular, the elastic body <NUM> usefully covers the cartridge <NUM> at the openings <NUM>.

In particular, said elastomer is a rubbery polymer with bonds capable of strengthening its structure by improving the mechanical performance of the polymer itself and giving the polymer elastic properties similar to those of natural rubbers. In particular, the elastomer is capable of undergoing very wide elastic deformations.

Thanks to its intrinsic elastic properties, the elastic body <NUM> performs a function of pumping the fluid to be dosed, being extendable between a first condition, of rest with respect to the measurement operation, in which it is arranged adherently against the external surface of the cartridge <NUM>, and a second, expanded condition, in which it is pushed by the fluid to adhere to the inner wall of the casing <NUM>, as described in detail below, to contain a measured volume VDOS of fluid, external to the previously mentioned clearance volume.

The elastic body <NUM> further forms an annular portion or peripheral rim <NUM>, at a respective insertion mouth, intended to act as a seal and to be retained between the central body <NUM> and the casing <NUM> in an assembled condition.

The casing <NUM> can form a preferably cylindrical cup <NUM>, adapted to be inserted, in the assembled state, externally to the cartridge <NUM>, with the interposed elastic body <NUM>.

Between the cup <NUM> of the casing <NUM> and the elastic body <NUM> in the first rest condition an external chamber <NUM> is therefore defined, containing a measuring volume VDOS, substantially given by the difference between the total volume inside the cup <NUM> and the aforementioned clearance volume VN. In practice, said measuring volume VDOS corresponds to the volume occupied by the fluid to be measured, which, in a feeding step through the connection portion 11a, passes through the openings <NUM> of the cartridge <NUM>, until the elastic body <NUM> expands in the second, expanded state, attached to the inner wall of the cup <NUM>.

At a wall of the cup <NUM> a duct <NUM> is preferably obtained for injecting a contrast fluid, for example air and/or nitrogen, so as to adjust the pressure acting on the outer wall of the elastic body <NUM>. For example, it is possible to provide that the duct <NUM> is made at a bottom <NUM> of the cup <NUM>.

The bottom <NUM> can in turn be separated from the rest of the cup <NUM>, being movable, for example, axially sliding inside the cup <NUM> with the interposition of corresponding sealing means <NUM>, so as to be able to adjust, in particular micro-adjust, the measuring volume VDOS. To allow such adjustment, the movable bottom <NUM> can be carried by a sleeve <NUM>, inserted externally to the cup <NUM>.

Guide means, for example of the threaded type, may be provided on corresponding facing surfaces of the sleeve <NUM> and of the cup <NUM> to guide an axial adjustment motion. For example, the sleeve <NUM> may be actuated manually or by suitable actuation means, such as a servomotor or other similar means.

The same casing <NUM> may have a fitting <NUM>, applied for example to the base of the sleeve <NUM>, if provided, or directly to the aforementioned bottom <NUM>, as a continuation of the duct <NUM>, to enable connection to a pressurizing duct adapted to feed the contrast fluid to the expansion of the elastic body <NUM>. The fitting is therefore mounted in communication with the duct <NUM> which flows into the external measuring chamber <NUM> and which preferably protrudes externally to the sleeve <NUM> where it can be joined to the fitting <NUM> by means of suitable coupling means.

The casing <NUM> may finally comprise a fixing portion 13a, usefully conjugated to the locking portion 11c of the central body <NUM>. For example, the fixing portion 13a may form a flanged element <NUM>, intended to make the fixing to the central body <NUM> by coupling to the corresponding hooking element <NUM>. The fixing portion 13a is preferably shaped at one end of the casing <NUM>, developing for example transversely to the longitudinal axis A.

The measuring device <NUM> may further comprise a fixing member <NUM>, for example of the clamp or jaw type, adapted to peripherally engage and lock together the locking portion 11c of the central body <NUM> with the fixing portion 13a of the casing <NUM>.

It is important to note that the casing <NUM> is not subject to contact with the fluid to be measured, as this is contained, in operation, within the elastic body <NUM>. Therefore, in choosing the material for its manufacturing it is possible to neglect contact with such a fluid.

The operation of the measuring device according to the invention is understandable from the foregoing description.

In an initial phase the fluid to be measured is fed in a controlled manner to the tank <NUM> and maintained at the containment pressure P<NUM>.

The elastic body <NUM> of the measuring device <NUM> is initially arranged in the first, rest condition. In particular, in this circumstance the contrast fluid fed to the external chamber <NUM> and present between the casing <NUM> and the cartridge <NUM> is maintained at a pressure P<NUM>, lower than the containment pressure P<NUM>.

In the next feeding step, the opening of the first shut-off device <NUM> present on the suction duct <NUM> is controlled or in any case actuated. The fluid to be measured is then fed at pressure P<NUM> along the suction duct <NUM> to the internal chamber <NUM> of the measuring device <NUM>. The pressure difference P<NUM>-P<NUM> between the fluid in the inner chamber <NUM> and the contrast fluid in the outer chamber <NUM> makes the fluid to be measured flow through the openings <NUM> and acts on the elastic body <NUM> determining its elastic expansion up to the second, expanded condition, i.e. up to its adhesion to the inner wall of the cup <NUM>.

In this phase, an amount of fluid corresponding to the measuring volume VDOS defined by the external chamber <NUM> is collected, then measured, externally to the containment portion 11b.

The first shut-off device <NUM> is then closed and the second shut-off device <NUM> is opened.

A spring back effect acting on the elastic body <NUM>, possibly with the aid of a pressurizing action exerted by the contrast fluid, air or nitrogen for example, fed through the duct <NUM>, pushes the VDOS of fluid to be measured to flow back through the openings <NUM> and brings the elastic body <NUM> back to the first rest condition. The measuring volume VDOS is thus pushed towards the delivery duct <NUM> to the dispensing unit <NUM>.

The VDOS volume that may be measured by the described measuring system may preferably be in a range between <NUM> and more than <NUM> liter for each measuring cycle.

The described measuring system may be operated manually but may also be associated with semi-automatic or automatic machines for measuring fluids.

In a second embodiment shown in <FIG> and <FIG> by way of an example, the measuring device <NUM>' may be used in a disposable manner. This embodiment is useful, in particular, for the measurement of dangerous fluids or which require particular sterility conditions, as it allows to avoid onerous and complicated washing operations.

In particular, the measuring device <NUM>' may be provided as a disposable measuring kit <NUM>, together with the necessary flexible tubing and fittings connecting to the suction and delivery of a circuit comprising an automatic or semi-automatic machine for measuring fluids.

Said tubing is preferably made of silicone material.

As aforesaid, the measuring device <NUM>' comprises the central body <NUM>', the elastic body <NUM>' and the casing <NUM>'.

More precisely, the central body <NUM>' forms the attachment portion 11a', for connection to the suction duct <NUM> and delivery duct <NUM>, for example by interposing a Y-shaped connecting member <NUM>, as well as the containment portion 11b' and the locking portion 11c'.

The containment portion 11b' in turn shapes the cartridge <NUM>' with the openings <NUM>'.

Unlike the first shown embodiment, the elastic body <NUM>' is made integral with the cartridge <NUM>' at the peripheral rim <NUM>', remaining for the rest expandable between the first state and the second state, as hereinbefore described.

The casing <NUM>' is made by the cup <NUM>', wherein the bottom <NUM>' is fixedly integrated. The duct <NUM>' for the pressurization of the external chamber <NUM>' is also made integrated, protruding from the cup <NUM>', preferably from the bottom <NUM>'.

The same cup <NUM>' flows into the fixing portion 13a' of the casing <NUM>', which can advantageously be made in the form of a narrowing <NUM>', suitable for the preferably adjustable insertion of the cartridge <NUM>'. In particular, the corresponding locking portion 11c' of the central body <NUM>' forms a shape section suitable for stable coupling with the narrowing <NUM>'. In practice, the cartridge <NUM>' can be inserted inside the casing <NUM>' through the constriction <NUM>', to be stably positioned there thanks to a corresponding generation of friction.

The cartridge <NUM>' can be adjustably inserted inside the casing <NUM>', along the longitudinal axis A', so as to correspondingly adjust the measuring volume contained in the outer chamber <NUM>'.

The casing <NUM>' can be advantageously made of plastic material, so as to permit a "disposable" use.

In particular, this solution makes it possible to provide the aforementioned kit <NUM>, possibly integrated with the necessary tubing and packaged in a special previously sterilized package, for example by gamma rays or in another useful way. The aforementioned packaging is so made ready for use, by simply opening and installing it in a protected environment.

According to a third embodiment, illustrated in <FIG>, the measuring device <NUM>" has technical characteristics, illustrated thereafter, which are also autonomous aspects, applicable and protectable separately from, and also in combination with each of the characteristics shown for the previous embodiments.

One of the aspects that distinguishes the third embodiment from the previous ones concerns the fact that the containing portion 11b" of the central body <NUM>", which defines therein said clearance volume VN, is advantageously divided into a suction section <NUM>" and a delivery section <NUM>".

The suction section <NUM>" and the delivery section <NUM>" are therefore separated from each other, so that the fluid to be measured cannot flow from one section to the other directly.

For this purpose, the suction section <NUM>" and the delivery section <NUM>" are preferably separated by an intermediate septum <NUM>", inserted inside the inner chamber <NUM>" preferably by interposing sealing means <NUM>".

The suction section <NUM>" is provided with respective suction openings 112a", which allow the passage of the fluid to be dispensed between the inner chamber <NUM>" and the outside of the containment body 11b" following the expansion of the elastic body <NUM>".

The delivery section <NUM>" is provided with respective delivery openings 112b", adapted to allow the return of the fluid to be delivered from the outside of the containment body 11b" to the internal chamber <NUM>" following the return of the elastic body <NUM>" to the rest condition.

The connection portion 11a" of the central body <NUM>" can provide for connection by means of special attachment means to a suction fitting <NUM>" and to a delivery fitting <NUM>".

In particular, the connection portion 11a" may define an internal channel, defined by the preferably axial coupling <NUM>", flowing into the internal chamber <NUM>" enclosed by the containment portion 11b", on which the suction fitting <NUM>" and the delivery fitting <NUM>" may be separately coupled, as described thereafter. This feature allows this channel to be divided into separate passages, i.e. arranged separately in communication with the suction section <NUM>" and with the delivery section <NUM>" of the inner chamber <NUM>" enclosed by the containment portion 11b".

The measuring device <NUM>" may for example comprise said fixing member <NUM>", for example of the clamp or jaw type, suitable for peripherally engaging and locking together the locking portion 11c" of the central body <NUM>" with a respective suitably flanged portion of the suction fitting <NUM>".

The suction fitting <NUM>"and the delivery fitting <NUM>" have a tubular shape. They preferably also have a development and a shape such that they can be inserted into each other so as to be able to access, separately, the channel defined by the connection portion 11a" of the central body <NUM>".

For example, the suction fitting <NUM>" may provide at least one straight section which, in the condition in which it is connected to the locking portion 11c", is oriented according to the longitudinal development of the central body <NUM>".

The delivery fitting <NUM>" may have at least in part straight development and shape a cross-section such as to be able to occupy only partially the channel defined by the connection portion 11a" and the inner chamber <NUM>" of the containment portion 11b".

The delivery fitting <NUM>", for example, may be inserted axially into the straight section of the suction fitting <NUM>", and then pass through the suction section <NUM>" and the separation septum <NUM>" between the suction section <NUM>" and the delivery section <NUM>", so as to be directly in communication with the delivery section <NUM>" only.

The delivery fitting <NUM>" may in any case directly connect the delivery duct <NUM> with the delivery section <NUM>" of the containment portion 11b" of the central body <NUM>", while the suction fitting <NUM>" may directly connect the suction duct <NUM> to the suction section <NUM>".

More precisely, the septum <NUM>" may usefully comprise a hole <NUM>" which allows the sealing engagement of the delivery fitting <NUM>".

In the embodiment illustrated in <FIG>, the suction section <NUM>" is arranged adjacent to the connection portion 11a", while the delivery section <NUM>" is arranged along the longitudinal axis A", opposite to the connection portion 11a", beyond said septum <NUM>".

Alternatively, it is possible to provide that the arrangement of the suction and delivery sections is reversed or different, but that in any case they are connected separately and respectively to the suction fitting <NUM>" and to the delivery fitting <NUM>".

According to a further independent aspect, applicable to measuring devices of different types, the measuring device <NUM>" can further provide a valve element <NUM>", movable alternatively between an open state, at which the valve element <NUM>" is distant from the suction openings 112a", to allow the passage of fluid from the suction section <NUM>" to the outside of the containment portion 11b", in a suction step, and a closed state, at which it is moved towards the same openings, so as to close them, to allow the passage of the VDOS measuring volume of fluid sucked in and collected outside the containment portion 11b", in a delivery step, only through the delivery openings 112b".

The valve element <NUM>" thus acts as a non-return valve, as it alternately opens the passage to the fluid to be sucked and closes the same passage in the delivery phase, to prevent the sucked fluid, collected externally to the cartridge <NUM>", from returning towards the suction fitting <NUM>.

The valve element <NUM>" can therefore usefully cooperate with the first shut-off device <NUM> arranged on the suction duct <NUM>, acting in a concordant manner, in the relative open and closed phases.

More generally, the valve element <NUM>" is advantageous in the transitory, open and closed phases of the shut-off devices <NUM>, <NUM>, present on the supply and distribution circuits, the suction circuit <NUM> and the delivery circuit <NUM>, of the fluid to be measured.

The valve element <NUM>" is preferably positioned so as to alternately engage the suction openings 112a".

In addition, the valve element <NUM>" is made of a material impermeable to the fluid to be measured.

Advantageously, the valve element <NUM>" may be formed of an elastic material, so as to be elastically deformed by the fluid-dynamic action of the flow of pressurized fluid, in the suction phase, at least locally freeing the suction openings 112a" (see in particular <FIG>).

In the delivery phase, however, the valve element <NUM>", in the absence of fluid dynamic stress from the fluid coming from the suction duct <NUM>, can return to a rest condition, engaging the suction openings 112a", until they are occluded.

The valve element <NUM>" may preferably be made of an elastic band, in particular annular, fitted around the cartridge <NUM>" at the suction openings 112a".

In practice, in the open state the valve element <NUM>" may assume an expanded state, in which the respective zones facing the suction openings 112a" are lifted by the cartridge <NUM>", freeing the passage to the fluid coming from the suction section <NUM>" of the inner chamber <NUM>".

In the closed state the same valve element <NUM>" may also assume a retracted state, in which it is attached to the cartridge <NUM>", thus blocking the passage of fluid through the suction openings 112a".

In the described embodiment, for example, the suction openings 112a" are arranged on two rows transverse to the longitudinal axis A", one after the other longitudinally, each being distributed radially around the axis of the containment portion 11b". In this case the valve element <NUM>" covers, in said closed state, both the rows of suction openings 112a" and an intermediate zone therebetween. In the open state, on the other hand, the valve element <NUM>" has respective annular, opposite edges, raised by the suction openings 112a". Lifting said edges causes an open passage to the outside of the cartridge <NUM>". In the same configuration, the element <NUM>' is arranged according to a convex state towards the outer chamber <NUM>", i.e. towards the environment external to the cartridge <NUM>", while an intermediate annular portion remains attached to said intermediate zone, free of openings, next to the cartridge <NUM>" (see <FIG>).

According to a still further independent aspect, applicable to measuring devices of different type, the measuring device <NUM>" may also comprise a filtering element <NUM>", preferably arranged at the delivery openings 112b", to precisely regulate the flow rate of the fluid to be measured.

In particular, the filter element <NUM>" produces a pressure drop in the fluid flow passing through the delivery openings 112b" towards the delivery duct <NUM>, so as to precisely control the flow rate of the fluid conveyed towards the delivery duct <NUM>. In particular, the filter element <NUM>" may counterbalance with optimal precision the contrasting action exerted by the contrasting fluid that can act on the elastic body <NUM>".

The filter element <NUM>" may be made for example from a tubular band, suitably fitted onto the cartridge <NUM>", in particular to cover the delivery openings 112b", to filter the fluid flow collected outside the cartridge <NUM> " to delivery section <NUM>".

Therefore, the filter element <NUM>" is made of a material that is at least partially permeable to the fluid to be measured, for example of a material in the shape of a net.

According to a further aspect, which may be independent, applicable to measuring devices of different types, the elastic body <NUM>" has an open end <NUM>", for example at the top of the measuring member <NUM>", suitable for being retained on the central body <NUM>" at the aforementioned annular portion <NUM>', and an opposite closed end <NUM>", for example at the base of the measuring member <NUM>" itself (see <FIG>).

The elastic body <NUM>" is preferably made of a tubular element, in which the closed end <NUM>" has a joint <NUM>".

This joint is preferably made by a welded end edge.

A further autonomous aspect, also applicable to measuring devices of other types, concerns the fact that the elastic body <NUM>" is assembled inside the casing <NUM>", in such a way as to be retained on the external wall of the containment portion 11b", as well as at the annular portion <NUM>", also at a second annular portion <NUM>", for example close to the closed end <NUM>". In this way the expansion of the elastic body <NUM>" is advantageously segregated between the annular portion <NUM>" and the second annular portion <NUM>", enabling the definition of the measuring volume VDOS in a very precise way.

For this purpose, the elastic body <NUM>" can be inserted inside the duct <NUM>" for feeding the contrast fluid, obtained in the casing <NUM>", being so retained by the respective internal wall in the expansion phase.

The duct <NUM>" may in turn comprise internal grooves <NUM>" which extend from the inlet of the conduit <NUM>" itself up to facing the external chamber <NUM>", to allow the inflow and outflow of the contrast fluid to and/or from the chamber <NUM>".

The grooves <NUM>" may be made, for example, in the shape of knurls.

The casing <NUM>" may be made in several parts, preferably in a pair of half-parts, enabling the correct clamping of the elastic body <NUM>" between the central body <NUM>" and the casing itself. For example, the aforementioned half-parts can be made in the form of respective half-shells separated along a median plane containing the longitudinal axis A".

To this end, the central body <NUM>" may comprise a first collar 119a" (see <FIG>). Correspondingly, each half part of the casing <NUM>" may comprise a respective annular seat <NUM>" adapted to receive the first collar 119a", to center the assembly of the central body <NUM>" and correctly tighten the elastic body <NUM>", at the annular portion <NUM>" and the second annular portion <NUM>".

For example, the measuring device <NUM>" may further include a shell <NUM>" assembled externally to the casing <NUM>", in order to lock, in turn, the respective half-parts of the latter.

The shell <NUM>" is preferably made of a pair of half-shells, a first half-shell <NUM>" and a second half-shell <NUM>". For example, the first half-shell <NUM>" and the second half-shell <NUM>" may be joined at a median plane transverse to the longitudinal axis A".

The first half-shell <NUM>" and the second half-shell <NUM>" can be fixed by locking means <NUM>", for example of the clamp type. In this case it is useful that the half-shells <NUM>", <NUM>" suitably provide a flange-shaped portion, adapted to be engaged by the locking means <NUM>" (see <FIG> and <FIG>).

The first half-shell <NUM>" may stably enclose the casing <NUM>" and, at least partially, the connecting portion 11a" of the central body <NUM>", for example by interposing sealing means <NUM>" (see <FIG>).

To allow correct interlocking, the central body <NUM>" may further comprise a second collar 119b" and correspondingly the first half-shell <NUM>" can provide a respective stop <NUM>", adapted to stably receive the second collar 119b" (see <FIG>).

The second half-shell <NUM>" may instead enclose the bottom of the casing <NUM>" where the duct <NUM>" is made.

The same half-shell <NUM>" may form a fitting opening <NUM>" for connection to the contrast fluid supply circuit.

Preferably the second half-shell <NUM>" is formed around the bottom <NUM>" of the casing <NUM>", so as to define outside thereof an inlet chamber <NUM>" for the contrast fluid, which develops between the conduit <NUM>" and the connection opening <NUM>" and which can receive the contrast fluid.

The operation of the measuring device according to the third embodiment is similar to that already described.

In particular, in the feeding step, the opening of the first shut-off device <NUM> present on the suction duct <NUM> is controlled or, in any case, actuated. The fluid to be measured is then fed at pressure P<NUM> along the suction duct <NUM> to the internal chamber <NUM>" of the measuring device <NUM>", reaching the suction section <NUM>" through the suction fitting <NUM>".

The pressure difference P<NUM>-P<NUM> between the fluid in the inner chamber <NUM>" and the contrast fluid in the outer chamber <NUM>" opens the valve element <NUM>", makes the fluid to be measured flow through the suction openings 112a" and acts on the elastic body <NUM>" determining its elastic expansion up to the second, expanded state, that is up to its adhesion to the inner wall of the casing <NUM>".

In this phase, an amount of fluid corresponding to the measuring volume VDOS defined by the external chamber <NUM>" is collected, then measured, externally to the containment portion 11b".

A spring back effect acting on the elastic body <NUM>", possibly with the aid of a pressurizing action exerted by the contrast fluid, air or nitrogen for example, fed through the connection opening <NUM>" and the duct <NUM>", pushes the VDOS of fluid to be measured to flow through the delivery openings 112b" in the delivery section <NUM>" and brings the elastic body <NUM>" back to the first rest condition. The measuring volume VDOS is thus pushed towards the delivery duct <NUM>, through the delivery fitting <NUM>", to the delivery unit <NUM>. The thrust of the fluid outflow is advantageously regulated thanks to the presence of the filter element <NUM>" fitted to cover the delivery openings 112b".

The measuring device described by way of example is susceptible to numerous modifications and variations depending on the different needs.

In the practical embodiment of the invention, the materials used, as well as the shape and the dimensions, may be modified depending on needs.

Claim 1:
A measuring device for a fluid to be measured, comprising a central body (<NUM>, <NUM>', <NUM>") equipped with a connection portion (11a, 11a', 11a") for connection to at least one suction duct (<NUM>) and to at least one delivery duct (<NUM>) of said fluid, and with a containment portion (11b, 11b', 11b") which defines an internal cavity (<NUM>, <NUM>") for a clearance volume (VN) of said fluid and comprises a plurality of openings (<NUM>, <NUM>', 112a", 112b") for the passage of said fluid outside said containment portion (11b, 11b', 11b"), a casing ( <NUM>, <NUM>', <NUM>") mounted externally to said containment portion (11b, 11b', 11b") so as to define between said casing (<NUM>, <NUM>', <NUM>") and said containment portion (11b , 11b', 11b") an external chamber (<NUM>, <NUM>") suitable for containing a measuring volume (VDOS) of said fluid, and an elastic body (<NUM>, <NUM>', <NUM>") fitted externally to said containment portion (11b, 11b', 11b") and retained by an annular portion (<NUM>, <NUM>', <NUM>") between said central body (<NUM>, <NUM>', <NUM>") and said casing (<NUM>, <NUM>', <NUM>"), said elastic body (<NUM>, <NUM>', <NUM>") being expandable between a first rest condition, in which said elastic body (<NUM>, <NUM>', <NUM>") adheres to said containment portion (11b, 11b', 11b") and a second, expanded condition, at which said elastic body (<NUM>, <NUM>', <NUM>") is expanded until it occupies said measuring volume (VDOS) of said outer chamber (<NUM>"), due to a flow of said fluid through said openings (<NUM>, <NUM>', 112a", 112b"), characterized by said casing (<NUM>, <NUM>', <NUM>") having a duct ( <NUM>, <NUM>', <NUM>") for feeding a fluid which contrasts the expansion of said elastic body (<NUM>, <NUM>', <NUM>").