Self compensated, adjustable fluid emitter, particularly in irrigation systems.

The present invention relates to a self compensated, adjustable fluid emitter, particularly intended to be used in irrigation systems, which emitter comprises : a casing externally delimiting a volume which is divided into a first chamber and into a second chamber by a membrane that can be elastically deformed; an inlet that can be connected to a fluid supplying source and communicating with said first chamber; an outlet communicating with said second chamber; said first and said second chamber being in communication one with the other by means of at least a communicating duct; means for retaining in a fixed position said membrane dividing the first chamber from the second chamber and allowing said membrane to be elastically deformed when said membrane is subjected to a fluid pressure difference between said first chamber and said second chamber, said membrane being deformed such that at least a portion thereof changes its position with respect to said outlet, modifying the flow rate of the fluid through said outlet depending on the pressure difference and so on the deformation of the membrane that goes closer and/or farther away from the outlet so

the flow rate of the fluid through said outlet is controlled and kept constant by said membrane despite variantions in the fluid pressure at least at the inlet or outlet. Particularly the flow rate or the flow amount through said outlet is reduced when the membrane is deformed going closer to the outlet while the flow rate of the fluid increases when the membrane is deformed going farther away from said outlet, therefore the flow rate of the fluid through said outlet is controlled and kept constant by means of said membrane despite fluid pressure variations at least at the inlet or outlet.

Fluid emitting devices , particularly for irrigation systems are known. For example U.S. 4,428,397 describes a device of this type.

However above mentioned devices have some drawbacks. The adjustment of the flow rate in relation to the pressure difference between the two chambers divided by the membrane is solely obtained by means of structural and elasticity charachteristics of the membrane. Therefore the membrane is the only functional member determining the adjustment for a very large range of pressure differences. Besides a saturation effect, i.e. a non-response effect when the fluid pressure difference in the two chambers divided by the membrane is over a certain maximum limit value and when it is lower than a certain minimum value, the continuous elastic stress of the material composing the membrane can cause the ageing of the material with regard to elastic characteristics and so it can lead to

the fact of not making possible the adjustment for pressure difference values close to extreme values of the pressure difference range within which the elastic behaviour of the membrane would guarantee the flow rate to be adjusted. For example when the membrane has to operate for a long time under high pressure difference conditions , the material can be inelastically deformed or stretched and so the elastic recovery to the original configuration cannot occur with the consequent fact of not making possible the adjustment upon a low pressure difference.

Moreover in order to guarantee a lasting and optimal elastic behaviour, the membrane has to be composed of a material with high elastic qualities and so quite expensive. This has a considerable effect as regards total costs of irrigation systems having a large number of said emitters .

In FR 1.299.719 a flow regulating device is known comprising two chambers separated by a membrane . One of the two chambers communicates with an inlet duct for a pressure fluid and the other one communicates with a duct delivering said pressure fluid, with the fluid passing from a chamber to the other one via a through hole provided in said membrane . An outlet spout cooperates with the membrane for defining a predetermined pressure in the corresponding chamber of the device that communicates with the delivering duct, which outlet spout can be adjusted with reference to its relative position with respect to the membrane. In such device, the distance between the membrane

and the outlet spout acts for allowing a pressure to be adjusted on the corresponding side of the membrane, but it does not allow a range of the flow rate to be adjusted. Moreover the membrane has to be perforated thus making it highly sensitive to wear and so it is subjected to breaking or to functionality loss.

In all known devices, the flow rate is adjusted by limiting and controlling the pressure. After all known devices do not act independently of the flow rate and pressure. The two magnitudes can be really correlated one with the other. However there is the need of independently adjusting the two magnitudes, at least as regards a certain range of pressures and/or flow rates.

Particularly the field of use to which the invention refers is the one of drop emitters . In this case, it is advantageous to have at disposal emitters able to change the flow rate of delivered irrigation water as a function of the seeding, growing, harvesting cycle. In this case the aim is to change the delivery of nutritious substances by increasing or decreasing them in the different evolution stages of said cycle corripondingly to needs and requirements of plants when growing and developping. All this without shocking or abusing plants and saving tools and workforce when replacing emitters.

The invention aims at providing an emitter of the type described hereinbefore, wherein, by means of simple and inexpensive arrangements it is possible to overcome above drawbacks of known emitters regarding the automatic control of the flow rate under different

fluid supplying conditions .

The invention achieves the above aims by providing a self compensated adjustable emitter, particularly intended for being used in irrigation systems, which emitter comprises characteristics described above, and wherein means for changing the position of the membrane with respect to the outlet, i.e. for mechanically and firmly changing the distance of said membrane from the outlet and/or means for mechanically and firmly changing the elastic behaviour of the membrane and/or for generating a firm deformation of said membrane are further provided.

According to an advantageous embodiment said means are provided in combination with means for reducing the pressure acting simultaneously and independently of the compensating membrane .

Said means for mechanically and firmly changing the elastic behaviour of the membrane and/or for generating a firm deformation of the membrane can be operated already in the idle condition thereof, i.e. when there is no fluid pressure difference in the two chambers divided by said membrane .

These means can be also operated when the membrane is in its operating condition and i.e. when there is a fluid pressure difference in the two chambers divided by said membrane .

Means for changing the position of the membrane with respect to the outlet can also be operated when the membrane is not urged and/or deformed, i.e. in its idle condition or when there is no fluid pressure

difference in the two chambers divided by said membrane .

According to the first variant, the membrane is supported by an intermediate flange of the inner space of the casing between two opposite walls one of which has the fluid inlet port and the other one has the outlet port, said two opposite walls being each one a part of a cup-like half-shell and the two cup-like half-shells being tightly coupled together and being movable so that they can go closer and/or farther away one with respect to the other and particularly said opposite walls, while only one of the two half-shells, particularly the half-shell having the wall wherein the inlet port is provided bears the flange fastening the membrane.

A preferred embodiment provides the casing to have a substantially cylindrical shape, the two half-shells being made of two opposing cup-like members and the two opposite walls having the inlet port and the outlet port respectively being composed of top and bottom walls of the cylindrical casing, while the membrane is supported by an inner perimetral annular flange provided in the cup-like member whose wall has the inlet port said flange being arranged parallel to said wall bearing the inlet port.

A variant embodiment provides the casing to be made of a cup-like member and of a wall closing the open side of said cup-like member slidably mounted inside said cup-like member going closer and farther away from an opposite bottom wall of said cup-like

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member .

Particularly the wall closing the cup-like member is composed of the surface of a closing cylinder having a certain axial extension. Even in this case the cup-like member bears the membrane, while the closing wall can be moved with respect to said membrane.

The cup-like member has a cylindrical shape and the bottom side thereof is circular and it bears the inlet port, the closing wall is also composed of a circular shaped wall that is substantially parallel to the bottom wall of the cup-like member and to the flange supporting the membrane as well as to the membrane in its not deformed configuration. In all above mentioned variants , ducts or passageways for the fluid from the first chamber provided on the side of the membrane faced towards the inlet port to the second chamber provided on the side of the membrane faced towards the outlet port are provided in the flange supporting the membrane and/or in the shell perimetral wall of one or both the cup- like members .

Moreover ducts and/or passageways have sections that not change in relation to fluid supplying and/or delivering conditions.

The second alternative, provides the membrane to be supported by means having a predetermined fixed position with respect to the outlet port, while spring means are provided that can be loaded in an adjustable way in order to obtain a variable deformation of the

membrane already when there is no pressure difference in the two chambers divided by it.

Particularly an embodiment provides the membrane to be retained by a perimetral flange provided at an intermediate position between two opposite walls delimiting the casing one of which wall bears the inlet port and the other one bears the outlet port while on the membrane side faced towards the wall bearing the outlet port there is provided a spring member interposed between said side of said membrane and a fixed abutment member, there being provided means for mechanically deforming said spring means for elastically loading them.

An embodiment provides said spring loading means to be composed of means compressing the spring member between said side of the membrane and said abutment member .

Particularly the abutment wall or the abutment member can be moved and constitute means compressing the spring member.

The preferred embodiment provides the abutment wall of said spring means interposed between said abutment wall and the membrane to be composed of the wall of the casing wherein the inlet port is provided, which wall can be tightly moved closer and farther away from the membrane, while the membrane is supported by means having a fixed position with respect to the outlet port.

The casing manufacturing can be similar to the one previously described with reference to the first

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alternative.

When the casing is made of two opposing cup-like members that can be tightly engaged and can be moved closer or farther away one with respect to the other, so the bottom side of one of the two cup-like member is the wall bearing the inlet port and acting as a abutment part that can be moved loading the spring member, while the second cup-like member has a bottom side with the outlet port and an inner perimetral flange supporting or fastening perimetral edges of the membrane which flange has a fixed position with respect to said bottom wall bearing the outlet port, thus a spring member being provided between the bottom wall of the cup-like member bearing the inlet port and the membrane when the two opposing cup-like members are tightly mounted.

A variant embodiment provides only a cup-like member whose bottom wall has the inlet port and a wall closing said cup-like member having an annular perimetral flange supporting peripherical edges of the membrane which flange is provided at a certain distance from the inner side of the closing wall .

Advantageously and as already described in the previous example with reference to the first alternative, also in this case, the casing may have a cylindrical shape the cup-like members having a cylindrical half-shell like shape and end walls of the cylindrical casing being provided one with the inlet port and the other one with an outlet port, while the membrane is borne by an inner, annular peripherical

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flange that is integral with the cup-like member or with the closing wall bearing the oulet port.

Advantageously the spring member is composed of a coil spring. The membrane is supported along an annular perimetral band that is continuous or discontinuous or provided with passageways for the fluid or passage ducts for the fluid, while it freely extends for the remaining part of the surface thereof, said membrane being al least rested on supporting abutment parts and particularly on an annular perimetral flange on the side thereof opposite to the chamber communicating with the fluid outlet port.

As regards means for reducing the pressure said means are integrated in the emitter and for example they consist of a labyrinth or a duct having an intricate path.

Advantageously said labyrinth or intricate duct is interposed between the inlet and the outlet of the communication duct connecting the two chambers separated by the membrane or said labyrinth or intricate duct forms at least partially the communication duct between said two chambers .

With reference to embodiments wherein the casing is composed of two parts tightly slidably connected according to a direction perpendicular to the membrane, and wherein a part has a shell wall tightly overlapping the shell wall of the other part, the intricate duct or labyrinth are provided along a perimetral band of one of said two overlapped and slidable perimetral walls

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and it is formed of a perimetral groove extending for an angle size smaller than 360° or it is like an annular groove or helicoidal groove extending along various coils , while one of the end of said annular groove leads to a chamber and the other end leads in the other chamber of the two chambers separated by the membrane .

Said duct can be provided in combination with any one of the above arrangements for the casing and particularly it is made like an annular or helicoidal perimetral groove provided on the outer side of the perimetral wall of one of the two half-shells or of the cylindrical member slidably and tightly entering inside the perimetral wall of the other half-shell member of the two half-shells or of the two parts composing the casing according to one or more of the embodiments described above.

According again to a further embodiment of the emitter according to the present invention, instead of an elastic member deforming the membrane on the side thereof faced towards the inlet, there are provided rigid members deforming the membrane which are provided at a predetermined distance from the membrane and it is such that in a position of the membrane intermediate between the two chambers, the membrane merely rests against said deforming means without being deformed by them, while in a position moved towards the chamber where the inlet leads i.e. a position reducing the size of said chamber, said membrane is deformed by said rigid deforming means towards the chamber wherein the

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outlet leads and in a modified position increasing the volume of the chamber wherein the inlet leads the membrane is moved away from said rigid deforming means . Said rigid deforming means are composed of a spout extending the inlet towards the membrane which spout projecting at a predetermined extent towards said membrane has an inner supply duct leading at the end side of the extending spout intended to contact the membrane and has a radial or side port for supplying the fluid in the peripheral wall.

By means of the characteristics of the present invention, it is possible to pre-set a certain distance of the membrane from the outlet port both by bringing closer or farther away said outlet port from the membrane that is in its idle condition i.e. without fluid pressure differences in the two chambers divided by the membrane or without a deformation, and causing a deformation of the membrane by elastically and mechanically pre-loading it leading to a greater or lower deformation when there is no pressure difference between the two chambers divided by the membrane . That allows to calibrate emitters such that they can always operate in a restricted adjustment range as regards the adjustment caused only by the elastic deformation of the membrane due only to intrinsic elasticity characteristics thereof. That allows to have emitters with a longer lasting with reference to the automatic adjustment effect of the flow rate, but also to use less noble and less expensive materials for membranes without compromising the system functionalities but

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drastically decreasing costs for manufacturing systems.

By means of characteristics described above, the emitter according to the present invention allows the flow rate of the delivered fluid to be adjusted and the pressure to be adjusted. Both functions are independent one from the other. Moreover, the fact of adjusting the flow rate and the pressure allows self compensating functions for the delivered flow rate to be provided in different ranges of the flow rate or for different values of the flow rate that are pre-set by moving and/or preloading the membrane .

The diagram of figure 11 shows the trend of the flow rate as a function of the pressure for three different emitter adjustments. In this case it can be noted that for three different values of the flow rate, the emitter performs a self compensation as the pressure increases, while keeping the flow rate constant at the predetermined value.

Therefore by acting on the relative position of the two half-shells and so on the distance between the membrane and the mouth of the outlet duct it is possible to set a value of the flow rate that is kept independently of the change in the pressure value in a particularly high range and in the example of figure 11 it is from 1 to 4 atmospheres.

Characteristics of the invention and advantages deriving therefrom will be more clear from the following description of some embodiments shown as a not limitative example in annexed drawings wherein: Fig.l is a first embodiment of the present

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invention wherein the preventive adjustment of the operating range of the adjusting membrane is obtained by modifying the distance of said adjusting membrane in its idle condition from the outlet port, i.e. without pressure differences on the two sides of the membrane or under the not-deformed condition of the membrane.

Figures 2 and 3 are the example of figure 1 with the distance of the membrane from the outlet of the emitter set in two different ways and with the membrane deformed by a pressure difference.

Figure 4 is a variant embodiment wherein the membrane is subjected to a previous deformation that can be adjusted by spring preloading means in combination with a movement of the bottom wall bearing the membrane with respect to the inlet port in this example the membrane being not preloaded.

Figures 5 and 6 are two further operating adjusting conditions of the emitter according to figure 5 wherein the membrane is considerably deformed. Figure 7 is a variant embodiment of the example according to figures 4 to 6 and which variant provides the provision of means for reducing the pressure in the form of an intricate duct or a labyrinth interposed between the two chambers of the emitter in the communication duct.

Figure 8 is the variant of figure 7 applied to the embodiment of figures 1 to 3.

Figures 9 and 10 are a third variant embodiment of the device according to the present invention wherein rigid pressing or supporting means act on the side of

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the fluid inlet chamber instead of an elastic member against the membrane.

Figure 11 is a diagram of the emitter behaviour according to the present invention with reference to the change in the flow rate of the delivered fluid as a function of the fluid pressure and for three different values of the flow rate set in the emitter.

With reference to figure 1 , there is shown a fluid emitter, particularly an irrigation dripping device comprising a casing 1 inside which there is defined a space for storing the fluid to be delivered and it is provided with a inlet mouth 2 intended to be connected to a fluid source and with an outlet, particularly an outlet duct 3 for delivering the fluid drop by drop. In the shown embodiment, the duct composed of the inlet port and the outlet duct are coaxially arranged. And each of them is provided at one of two opposite upper or lower end walls 101 and 201 of the emitter casing 1.

The inner delimited space of the casing 1 is divided in two chambers Cl and C2 by a membrane 4 supported in an intermediate position between the two walls 101 and 201 by an inner peripherical flange 5 extending along the inner side of the shell wall 301 of the casing 1. The membrane made of elastic material tightly divides the two chambers Cl and C2 , while the latter are in communication by means of one or more ducts and/or one or more passageways made in the flange 4 and/or inside the thickness of the shell walls 301 of the casing 1 and which cannot be seen in annexed

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figures but are known per se in all realizations according to the prior art mentioned hereinbefore .

Therefore, as it results from the figure and from the previous disclosure, the membrane is a barrier that can be elastically deformed with the fluid freely flowing between the two chambers and from the inlet mouth 2 to the outlet duct 3. The membrane is supported and held only along a band of the peripherical edge, while the remaining inner portion of its extension is free to be deformed since it extends like a bridge on the open central region of the peripherical annular flange 5.

Ducts and passageways between the chamber Cl and the chamber C2 on the side of the membrane faced towards the inlet port 2 and towards the outlet duct 3 respectively, are such that under certain pressure conditions of the fluid inside the chamber Cl and inside the chamber C2 they generate two different pressures. Particularly, when the inlet fluid pressure is very high, and it is such that it is not possible to have the dripping action or the amount of the delivered fluid is too much with respect to the desired one, a pressure difference between the fluid in the chamber Cl and the fluid in the chamber C2 is generated in favour of the pressure inside the chamber Cl. As it is shown in following figures the higher pressure in the chamber Cl causes the membrane to be elastically deformed bending in the chamber C2 towards the wall bearing the outlet duct 3. In this case the membrane goes closer the entrance of the outlet duct 3 in the chamber C2 and

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it causes a reduction of the flow rate that depends on the higher pressure inside the chamber Cl achieving an automatic adjustment of the flow rate within desired ranges of the flow rate for delivering the fluid by dripping action.

Therefore the fact that the outlet duct 3 and the inlet mouth 2 are coaxially arranged is particularly advantageous since it maximizes and centres the deforming action with the position of the outlet duct 3. Moreover the rotational geometry concentric with the axes of the two ducts , of the membrane 4 and of the flange 5 are such choices that optimize the desired effect, but they cannot be considered as limitative ones . This is also true if the casing is chosen to be manufactured with a cylindrical shape with the two walls 101 and 201 composed of the end walls of the cylindrical casing 1, the shell wall 301 composed of the cylindrical shell wall 301, the flange 5 extending in a plane parallel to the two end walls 101 and 201 therefore as the membrane 4 and with the inlet mouth 2 and the outlet duct 3 that are coaxial with respect to the end walls 101 and 201 and to the axis of the cylindrical casing.

The inner surface of the wall 201 delimiting the chamber C2 on the side of the membrane faced towards the outlet duct 3 advantageously has a not flat shape with an axial annular projection 401 about the outlet duct 3 and therefore extending it towards the membrane 4. This annular, axial projection 401 can be advantageously provided with one or more radial grooves

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constituting a passageway for the fluid when the membrane is deformed at the greatest extent. In fact if the fluid supplying pressure in the chamber Cl increases too much, the membrane could be deformed such that the entrance of the outlet duct 2 in the wall 201 can be completely closed, causing the delivering flow to be stopped and so the irrigation fluid to be not present with the danger of damaging the crops . By providing the annular, axial projection 401 with radial grooves or through holes (not seen in figures) , the membrane cannot completely prevent the output flow even when it completely adheres against the most projecting surface of the axial projection 401 constituting the entrance of the outlet duct 3. For example in this case radial grooves would be closed only at the open side and the fluid would be able to pass from the chamber C2 towards the outlet duct 3 through them with a minimum flow rate guaranteed also in the case of fluid supplying pressures overcoming a maximum limit within which the membrane can automatically and progressively (i.e. depending on the supplying fluid pressure) acting in adjusting the flow rate.

According to a first embodiment shown in figures 1 to 3 , the flow rate of the delivering flow depending on the pressure of the fluid supplied to the dripping unit is adjusted not only in an automatic way solely by means of the intrinsic elasticity of the membrane 4 but also by a manual mechanical action aiming at presetting a certain operating condition of the membrane adapting it to changing conditions of the delivering pressure

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that are present in the system or with reference to the fluid supplying source to which the emitter is connected or has to be connected.

As it results from figures 1 to 3, this is achieved by the fact that the distance between the mouth of the outlet duct 2 , i.e. the inner surface of the wall delimiting the chamber C2 about the outlet duct 2 and in the case of the present example, the end surface of the axial projection 401 and the faced surface of the membrane 4 intended to cooperate with the mouth of the outlet duct 3 i.e. with said surfaces is made such that it can be adjusted and pre-set in order to reduce the passage opening depending on the pressure difference between the two chambers Cl and C2 and so in order to modify the flow rate.

In the embodiment of figures 1 to 3 the position of the wall 201 wherein the outlet duct 3 is provided is modified with respect to the membrane 4 i.e. to the flange 5 fastening it. Different specific arrangements are possible. The wall 201 wherein the outlet duct is provided can be made as that it can be tightly mounted and moved, as well as that it can be locked in place inside and along perimetral or shell walls 401 of a cup-like member that is integrally formed by the end wall 101 bearing the inlet port 2, by the shell or perimetral wall 301 with the inner flange 5 fastening the membrane 4. In the shown example this is made by providing the wall 201 wherein the outlet duct 2 is made as an axially elongated body that can be axially tightly moved inside

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the perimetral shell wall 301 in the direction coaxial to the outlet duct 2 and/or to the inlet duct 3 and/or in the direction perpendicular to the membrane 4. The coupling of the wall 201 or of the body 201 can be of any type and particularly the above mentioned cylindrical realization is advantageous since it allows a screw type coupling the body 201 making the movable wall being composed of cylindrical member provided with an external thread, while the shell wall 301 has a corresponding inner thread in the axial portion between the flange 5 and the free end edge opposite to the wall 101. The tight effect can be guaranteed for example by one or more O-rings interposed between the external shell wall of the cylindrical body forming the movable wall 201 and the inner side of the shell wall 301 of the cup-like member.

Other structural variants are possible for example the movable wall 201 bearing the outlet duct 3 can be also a part of a cup-like member opposing the cup-like member associated to the end wall 101 provided with the inlet duct 2. In this case , the outlet duct 3 can be made by a mouthpiece integral with the end wall 201 of said second cup-like member, while shell walls of the two cup-like members have such diameters that the inner diameter of the first cup-like member associated to the inlet mouthpiece 1 is greater or substantially equal to the outer diameter of the shell wall of the second cup- like member bearing the outlet mouthpiece. In substance the body 201 of the figure 1 and following ones is not a solid one but it is made hollow like a cup for a

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certain axial length, while for the remaining axial length it would have the diameter reduced such to make the outlet mouthpiece.

The two cup-like members can be also substantially symmetrical one with respect to each other, the only differences being the annular axial projection of the outlet duct 3 on the second cup-like member and the presence of the inner flange 5 on the first cup-like member associated to the inlet mouthpiece 2. Obviously the two variants have not to be intended as limitative ones , as well as references made to the rotational or cylindrical symmetry shape that are simpler from the a construction and description point of view, but they are not the only possible shapes the casing being possible to be made with any shape and there being also possible to provide any different orientation of the fluid inlet and outlet ducts 2 , 3 of the membrane 4. The only essential characteristic is the fact that the distance between the entrance of the outlet duct 3 in the chamber C2 and the membrane surface faced towards it can be varied and locked at the selected value . The arrow Fl in figures generally denotes the possibility to move the wall 201 in order to achieve this functionality in examples of figures 1 to 3.

Figures 5 and 6 show a variant of the present invention, wherein the initial distance is not adjusted i.e. the distance of the membrane from the entrance of the outlet duct 3 when it is in its idle condition, or when there is no deformation or where there is no

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pressure difference in chambers Cl and C2 divided by the membrane, but an initial predetermined deformation of the membrane is given by mechanical and preferably spring means when there is no fluid pressure difference in the two chambers Cl and C2. In this case, the initial distance of the membrane 4 from the entrance of the outlet duct 3, i.e. the distance of said membrane from the entrance of the outlet duct 3 when there is no a substantial pressure difference between the fluid pressure in the two adjacent chambers Cl and C2 divided by the membrane 4 is modified by acting on the membrane going closer and/or farther away from said entrance of the outlet duct 3 on the basis of a deformation caused by mechanical means and being adjustable. Different embodiments are possible providing a pressing member that is rigid or elastically pliable that can be pushed with a different force against the membrane on the side thereof faced towards the chamber Cl wherein the fluid inlet duct comes out directly connected to the supplying source.

Means for adjusting said pressing force can be provided in different configurations to be all considered within the reach of the person skilled in the art and also constructional choices. A preferred and advantageous embodiment that is shown in figures 5 to 6, provides a construction similar to the one of the previous embodiment, but wherein the wall 201 is made like a cup or at least with an end face faced towards the membrane that is made hollow like a cup and wherein the shell

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peripherical wall 501 forms a step-like enlargement supporting the outer peripherical band of the membrane . The step-like enlargement 601 is the same as the flange 5 in the previous embodiment, while like the embodiment of figures 1 to 3, the end wall member 201 can be axially moved towards the inlet duct, i.e. towards the end wall 101 of the cup-like member delimiting the chamber Cl that is associated to the inlet mouth 2.

A spring member, for example a coil spring 6 is interposed between the wall 101 and the cup-like member i.e. the end wall 101 associated to the inlet mouth 2 and the faced side of the membrane 4 that is the side thereof faced towards the end wall 101 bearing the inlet mouth 2. The member 201 can be moved with respect to the cup-like member according to one of the mode described with reference to the previous example and particularly for example by tightly screwing and/or unscrewing it inside the shell wall 301 of the cup-like member delimiting the chamber Cl particularly when pieces have a cylindrical shape or a rotational or cylindric symmetry shape defined above in more details . In this case it is to be noted that the membrane 4 , that is the flange supporting it is integrated in the body 201 and so it moves together with the surface of the extension axial projection 401 of the outlet duct 3 therefore the movement of the body 201 does not lead to a change of the distance between the mouth of the outlet duct 3 and the flange supporting the membrane as in the previous example, but it causes only the membrane 4 to go closer

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or farther away from the end surface 101 bearing the inlet mouth 2 and so it causes the coil spring 6 to be pressed at a gretaer or lower extent determining a deformation of the membrane 4 that can change depending on the compression of the spring 6. Therefore when there is no fluid pressure difference in the two chambers Cl and C2 it is possible to previously set a deformation of the membrane 4 corresponding to a different distance between it and the entrance of the outlet duct 3 and consequently a different flow rate.

Like in the previous example the casing 11 can have also other configurations different from the shown ones that however involve some functional and constructional advantages such as for example the screw coupling between the member 201 and the shell perimetral wall 301 of the cup-like member and also the fact that the membrane spring member inlet mouth 2 and outlet duct 3 are coaxial one with respect to the other that is achieved by means of the cylindrical shape or of the cylindrical symmetry.

From the functional point of view in both the variant embodiments it is possible to previously and manually or mechanically adjust the distance between the membrane and the entrance of the outlet duct when there is no pressure diffeence between the fluid pressure in the two chambers divided by the membrane, in order to define an operating point of the emitter corresponding to a predetermined flow rate where there is no said pressure difference. Therefore that allows to adapt the operating point of the emitter to average

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conditions of the supplying pressure such that it is not necessary always to act in extreme conditions of the possible adjusting range. In the first case the idle distance of the membrane from the entrance of the outlet duct is changed by moving the entrance of the outlet duct and the membrane one with respect to the other without changing the membrane configuration, i.e. without a deformation thereof or without the fluid pressure difference in the two chambers . On the contrary in the second case in said condition without a pressure difference between the fluid pressure in one chamber Cl and the fluid pressure in the other chamber C2 the membrane is subjected to a deformation modifying the distance between it and the entrance of the outlet duct. In both cases, when there is no pressure difference between the fluid pressure in one chamber Cl and the fluid pressure in the other chamber C2 the flow rate of the emitter is modified.

With reference to figure 7 , the emitter shown in this figure is the one of figures 4 to 6 so like structural parts use like reference numbers. The emitter of figure 7 is different from the one of figures 4 to 6 in that along the perimetral shell wall of the cylindrical body 201 closing the open side of the cup-like member being tigthly inserted in the cylindrical perimetral wall 301 of such cup-like member there is provided a groove 10 opened towards said shell wall 301 of the cup-like member and making a labyrinth or intricate duct one of the end thereof leading in the chamber Cl by an axial duct 11 and the other end

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thereof leading in the chamber C2 by a terminal duct 12. Ducts 11, 12 and the groove 10 together make the communication duct between the two chambers and at the same time they are a means for reducing the pressure. The groove 10 can be an annular one, or it can extend less than a round angle or it can extend for various coils having an helicoidal shape (not shown) .

By way of example in figure 7 there is also shown the seal 13 between the cup-like member and the cylindrical boby and in the example it is housed in a corresponding annular outer groove 14 of the cylindrical body and it is interposed between the groove and the inner surface of the shell wall 301 of the cup-like member. The example of figure 8 show the application of variants provided in figure 7 to the embodiment of figures 1 to 3 in combination with embodiments of figures 4 to 6.

With reference to figures 9 and 10, there is shown a further variant embodiment that is different from the preceding variants in that it provides means cooperating with the membrane and being stationary means pressing thereon when the two casing parts are brought one nearer the other one for more than a certain extent so the membrane gets closer to the inlet of the chamber Cl for more than a certain minimum extent .

In examples of figures 9 and 10 the like reference numbers are used for like structural parts or parts having the same function.

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In the chamber Cl the inlet 2 extends towards the membrane 4 with an extension spout 20 extending for a certain lenght. In an intermediate relative position condition between the two casing parts of the emitter that is with the membrane in an intermediate position spaced from the inlet 3 (fig.9) the extension spout 20 abuts against the membrane 4 so the axial outlet port of said spout is closed. In such condition a radial or side port 21 provided in the shell perimetral wall of said extension spout 20 guarantees the supply of the fluid in the chamber Cl . With the membrane 4 going further nearer the inlet 3, the extension spout 20 acts as a member deforming the membrane 4 (fig.10) so the latter is bent towards the outlet 4. The fact of moving the membrane farther away with respect to the position of figure 1 , on the contrary leads the membrane to go farther away from the extension spout 20 opening also the axial supply duct and so increasing the supply flow in the chamber Cl . As it results from figures 9 and 10, also in such embodiment there can be provided the pressure reducing device like examples of figures 7 and 8.

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