WO1993010389A1

WO1993010389A1 - Device for restricting fluid flow

Info

Publication number: WO1993010389A1
Application number: PCT/FR1992/001075
Authority: WO
Inventors: Yves Lecoffre
Original assignee: Helispire
Priority date: 1991-11-20
Filing date: 1992-11-20
Publication date: 1993-05-27
Also published as: AP376A; FR2683886A1; AP9200451A0; AU3163693A

Abstract

A device for restricting fluid flow comprises a rigid body (1) having a smooth surface (9); a fluid inlet tube (7) opening onto said smooth surface in a first region; a fluid outlet tube (10) opening onto said smooth surface in a second region removed from the first; and a wire (4) wound so as to form contiguous coils (A, 4B), which are applied against the rigid body's smooth surface (9). A channel (8) is so formed as to be delimited by said smooth surface, a coil and a coil contiguous to said coil. This results in a channel of reduced section having more or less the same length as the wire, said channel (8) serving to restrict fluid flow.

Description

DEVICE FOR RESTRICTING A FLOW OF A FLUID

The present invention relates generally to a device for restricting a flow of a fluid which passes through said device, and more particularly to a device which receives the inlet of fluid under a predetermined pressure and which controls the flow of fluid which leaves the device, such that this fluid flow rate is established at a precise predetermined value, this value being fixed or variable.

Document US-A-3,551,174 describes a tubular device intended to provide a passage of very small dimensions. The tubular device consists of a twist of a plurality of wires, this twisted assembly providing a passage of small section in which a fluid can flow. In general, it is intended to thus twist three wires together. A drawback of this device lies in the fact that the length of the passage is equal to the length of each wire, and therefore it is difficult to arrange a very long passage in an apparatus for which it is desired to obtain very small dimensions . On the other hand, it is not easy to ensure that the wires are joined, and therefore, the section of the passage can vary in a manner that is difficult to control. If the wires are of very small diameter, the sheath which surrounds the twisted wires is difficult to produce. Finally, it is very difficult to arrange such a device so as to obtain a fluid inlet passage and a fluid outlet passage. On the other hand, it is not possible to use such a device to constitute a device that can control and regulate at will and precisely a fluid flow.

An object of the present invention is to provide an apparatus for restricting a flow of a fluid which can deliver a very low flow rate of fluid, in a very precise manner, while being of a very simple design and while being able to be strongly miniaturised. Another object of the present invention is to provide such an apparatus which can also offer a possibility of precise adjustment of the fluid flow rate at will.

According to an essential characteristic of the invention, a fluid flow control device for restricting a flow of a fluid which passes through said device by entering the device by a fluid inlet and leaving the device by a fluid outlet, comprises: a rigid body having a smooth surface; a fluid inlet conduit which is in communication with said fluid inlet and which opens at said smooth surface at a first location; a fluid outlet conduit which is in communication with said fluid outlet and which opens at said smooth surface at a second location remote from the first location; and a wire wound so as to form contiguous turns and so that all the turns are applied against said smooth surface of said rigid body, whereby a channel is thus formed which is limited by said smooth surface, by any whorl and by a whorl adjoining any whorl, so that said channel has an area of reduced section and a length close to the length of the wire; and in that said first location is located in the vicinity of a first end of the wire so that the incoming fluid arrives in said channel in the vicinity of this first end of the wire and said second location is located in the vicinity of the other end of the wire so that the outgoing fluid comes from said channel in the vicinity of this other end of the wire, from which it follows that the fluid successively passes through the fluid inlet conduit, the channel and the fluid outlet conduit and is restricted in speed by the channel.

According to a particular embodiment of the invention, that said smooth surface of said rigid body is a surface cylindrical and in that said wire is wound helically against this cylindrical smooth surface so as to form a plurality of turns which are contiguous and which are applied against the cylindrical smooth surface. According to another embodiment of the invention, the apparatus further comprises: a deformable part of generally cylindrical shape comprising a first cylindrical surface which is applied with a certain force against the side of the helically wound wire which is opposite with respect to said smooth surface; and pressure applying means which applies a certain pressure radially to the other cylindrical surface of said deformable part in order to provide said force with which the first cylindrical surface of the deformable part is applied against the helically wound wire.

According to another embodiment of the invention, said means for applying pressure is constituted by a rigid part of revolution having a surface of revolution whose dimensions are slightly in interference with the dimensions of said first surface of the part deformable in order to compress this deformable part to create said force with which the cylindrical surface of the deformable part is applied against the helically wound wire.

According to another embodiment of the invention, said means for applying pressure consists of a closed chamber of generally annular and cylindrical shape which is limited: by said other surface of the deformable part and by a surface of a rigid, tight body which communicates with the fluid which enters or leaves said device, so that the pressure of the fluid which thus fills this chamber supplies the pressure of said means for applying pressure.

According to another embodiment of the invention, said smooth surface of said rigid body is a flat surface in that said wire is wound in a spiral around this flat smooth surface so as to form a plurality of turns which are contiguous and which are applied against the flat smooth surface.

According to another embodiment of the invention, the apparatus further comprises: a deformable part having the general shape of a disc, comprising a flat surface which is applied with a certain force against the wire wound in a spiral; and pressure applying means which applies a certain pressure to said deformable part in order to provide said force with which the planar surface of the deformable part is applied against the wire.

According to another embodiment of the invention, said means for applying pressure is constituted by a rigid part which has the general shape of a disc and which is permanently pushed against said deformable part in order to compress this part. deformable to create said force with which the surface of the deformable part is applied against the wire.

According to another embodiment of the invention, said means for applying pressure consists of a closed chamber having the general shape of a disc which communicates with the fluid which enters or leaves said device, so that the pressure of the fluid which thus fills this chamber supplies the pressure of said pressure application means. These objects, characteristics and advantages, as well as others of the present invention will be better understood during the detailed description of embodiments which follows, illustrated by the appended drawings among which: FIG. 1 is a view in longitudinal section partial showing the essential parts of a particular embodiment of an apparatus for restricting a flow of a fluid according to the invention; Figure 2 is a longitudinal sectional view of another embodiment of an apparatus according to the invention; Figure 3 is a longitudinal sectional view of yet another embodiment of an apparatus according to the invention; Figure 4 is a longitudinal sectional view of yet another embodiment of an apparatus according to the invention; Figure 5 is a longitudinal sectional view of yet another embodiment of an apparatus according to the invention; Figure 6 is a longitudinal sectional view of yet another embodiment of an apparatus according to the invention; Figure 7 is a simplified partial view in cross section showing a design detail of part of the device of Figure 6; Figure 8 is an enlarged partial view in longitudinal section showing another design detail of part of the device of Figure 6; Figure 9 is a schematic view showing a first possible application of an apparatus according to the invention; Figure 10 is a schematic view showing another possible application of an apparatus according to the invention; Figure 11 is a schematic view showing yet another possible application of an apparatus according to the invention; and Figure 12 is a schematic view showing yet another possible application of an apparatus according to the invention.

In all the figures, the same reference index indicates an identical or similar part or element. FIG. 1 illustrates an embodiment of an apparatus for restricting a flow of fluid according to the present invention.

The apparatus comprises a cylindrical body 1 comprising a fluid inlet 2 at one end and a fluid outlet 3 at the other end. A metal wire of circular section 4 is wound helically around the cylindrical body 1. The turns of the metal wire 4 are contiguous. A deformable piece 5 is arranged around the coiled metal wire

4. A spring 6 is arranged around the deformable part 5 and it is used to permanently exert pressure thereon so that the deformable part 5 is permanently pushed against the coiled wire 4. The deformable part is preferably elastically deformable and it can be produced for example from an elastomer. On the enlarged part of FIG. 1, it can be seen that the surface of the deformable part 5 which is in contact with the coiled wire 4 deforms by partially matching the external contour of the coiled wire 4, so as to establish a seal between part 5 and wire 4 and to decrease the volume of the inter-wire space located on the side of part 5.

A fluid supply duct 7 is formed in the cylindrical body 1 so as to communicate the fluid inlet 2 with at least one channel 8 formed between the adjacent turns 4A,

4B of the coiled wire 4 and the external surface 9 of the cylindrical part 1. The details of this channel 8 can be seen on the enlarged drawing part of FIG. 1. The apparatus according to the invention operates as follows. Fluid is sent under pressure at the inlet

2, the fluid passes through the conduit 7, then arrives in the channel 8. Then, the fluid circulates along this channel 8 which extends along the coiled wire 4. The fluid arrives at the other end from channel 8 from where it passes through a conduit

11 formed in the cylindrical body 1 to exit at the outlet 3.

The deformable part 5 makes it possible to firmly and tightly hold the turns of the wire 4 against the external cylindrical surface 9 of the cylindrical body 1. It can also be seen that the turns of the wire 4 are contiguous, so that the channel 8 constitutes a passage single helical, that is to say that the fluid cannot pass directly from a zone of the channel to an adjacent zone this same channel. In FIG. 2, which represents another embodiment of the invention, it can be seen that the device consists mainly of an external cylindrical body 20 having a smooth internal cylindrical surface 21 on which is applied a helically wound wire 4, its turns being joined. a deformable part 22 has a shape external cylindrical and is engaged in the internal space of the wound wire 4. The external diameter of the deformable piece 22 is slightly less than the internal diameter of the wound wire 4, but the end pieces which respectively include the inlet 2 and the outlet 3 are, during assembly, close to one another and thus compress the deformable part axially, causing its expansion and consequently a pushing effect on the wound wire 4 which therefore remains applied against the smooth internal cylindrical surface 21 of the external cylindrical body 20. The fluid enters via an inlet 2, passes, via a radial channel, into a sealed internal chamber 23 which surrounds on the outside one end of the wound wire 4, then passes into the channel 8 which is formed between the contiguous turns 4A, 4B of wire 4 and the smooth surface 21, follows this channel 8 to the other end of wire 4, passes into another sealed internal chamber 24 which surrounds on the outside the other extrem ity of the wire 4 and arrives, via a radial channel, in the outlet 3. The fluid is thus greatly restricted in flow rate during its flow in the channel 8.

FIG. 3 illustrates another embodiment of the apparatus according to the invention. This apparatus comprises a disc-shaped body 30 having a flat smooth surface 31. A metal wire 32 is wound in the form of a spiral, the turns of the spiral being contiguous. The wire wound in a spiral 32 is placed on the smooth surface 31 of the disc-shaped body 30. A deformable piece in the form of a disc 33 is placed against the other side of the wire 32. The apparatus is completed by a housing 34 having an internal cylindrical housing 34 having a bottom 36. The deformable part 33 is housed in the bottom 36 of the recess 35 and a means of applying pressure makes it possible to compress the assembly formed by the deformable part 33, the wire 32 and the disc 30. This means comprises a plug 37 screwed into the recess 35 and which compresses an elastic body 38 which in turn pushes against a movable rigid part 39 which in turn pushes the disc 30. A fluid inlet 2 is provided in the plug 37 and it communicates via a conduit 40 with a conduit 41 formed in the part 39 and which opens into a conduit 42 formed in the disc 30 at or near its periphery. A fluid outlet 3 is formed in the bottom 36 of the housing 34 and it communicates with a central zone of the smooth surface 31 of the disc 30 via a hole 43 formed in the deformable part 33 and a central space 44 left in the center by the wire wound in a spiral 4. The fluid therefore enters through the inlet 2, then passes successively in the conduits 40, 41, 42, then passes through the channel 8, emerges at the level of the space 44, then crosses the hole 43 and comes out through the outlet 3. The fluid is restricted in its flow during its passage in the channel 8.

The adjustment of very low fluid flow rates can be achieved by the use of very long channels and of small section in which the flow is laminar. This type of flow is obtained when the Reynolds number of the flow, Re, is less than approximately 2000.

Re = VD / v V being the average speed of flow, D the diameter of the tube when it is of cylindrical section or a hydraulic diameter for another shape of section and v the dynamic viscosity of the fluid.

An example is given of the dimensions of the basic solution shown in FIG. 1. The wire 4 has a wire diameter of 0.5 mm. Its internal winding diameter is 20 mm and the length of the coiled wire located between the arrival and departure of the fluid is 20 mm. The number of turns forming the channel is therefore equal to 40 and the length of the channel (which is substantially the length of the unwound wire) is, therefore, about 2400 mm, or 2.4 m. The order of magnitude of the water flow which would pass through this channel 8 under a pressure of 10,000 Pascals would be 8 10 " ^{1 1} m ³ / s, or 7 cm ³ / day.

It will be noted that the flow rate is inversely proportional to the length of the channel 8, to the pressure difference and to the dynamic viscosity μ of the fluid. It is proportional to the power 4 of dimensions, therefore at the power 4 of the diameter of the wire 4. It can be calculated a priori from known numerical methods for laminar flows. It can also be deduced from the similarity laws set out above, from an experiment carried out on a reference channel.

It is advantageous, in certain applications, to be able to adjust the flow rate of fluid passing through a valve. Figure 4 gives a solution to simply perform this operation while keeping the basic principles set out above. The wire 4 is, as before, wound on a support cylinder 50. It is surrounded by the elastic sleeve 5 and pressed by a spring 6. The wire is held axially by two parts 51, 52 mounted inside a cylinder 53 The cylinder 50 is free to move axially. Its movement is ensured by a screw 54. This comprises a collar 55 preventing it from moving axially By rotating the screw 54, the cylinder 54 is made to move axially, which makes it possible to modify the position of the point 56 of fluid injection, this point 56 corresponding to one end of a groove 57 formed in the external surface of the cylinder 54 and which communicates with a fluid inlet 2 formed in the part 51. A fluid outlet 3 is formed in the part 52 and it communicates with the other end of the wound wire 4 via a conduit 58.

The fluid enters the groove 57 described above. It enters the turns of spring 4 at a variable point 56. It passes through the turns of the spring, then joins the outlet 3. A channel of variable effective length is thus produced, since it suffices to move the cylinder 50 axially to change the point of introduction of the fluid. FIG. 5 represents another variant embodiment of the invention in which the fluid flow control device according to the invention is modified so as to be able to be controlled in order to deliver a flow of fluid which can vary at will, from a flow zero up to a determined maximum flow rate, depending on a position of a control element. In this variant embodiment, the fluid flow control device likewise comprises a central cylindrical body 60, on which a wire 4 is wound helically so that its adjacent turns are contiguous. However, the cylindrical central body 60 has a number of radial channels 62, 63, 64, 65 which open at the external cylindrical surface 66 of the cylindrical body 60 in different longitudinal positions. Thus, the first radial channel 52 opens in the vicinity of the left end (in the figure) of the wound wire 4, in a manner similar to the fluid inlet channel in the first embodiment (Figure 1), and the last channel 57 opens a short distance from the opposite right end (in the figure) of the wound wire 4. The other radial channels 63 and 64 are distributed equidistant longitudinally between the end channels 62 and 65. The internal end of each channel is in communication with a corresponding longitudinal channel 67 to 70. As can be seen in FIG. 5, the longitudinal channels open out at the level of a radial planar end 71 of the cylindrical body 60 so as to be located on a circle concentric with the cylindrical body 60 and to be distributed circumferentially equidistantly. The radial planar surface 71 is produced in the bottom of a cylindrical recess machined inside one end of the cylindrical central body 60. In this cylindrical recess, a fluid flow control part 73 of cylindrical shape is housed with minimum radial clearance. The fluid flow control part 73 can rotate inside the recess and is sealed at its peripheral part with respect to the cylindrical central body 60. A control lever 75 makes it possible to be able to actuate at will so as to external the fluid flow control part 73 so as to bring it into a selected determined rotational position. The fluid flow control part 73 has a longitudinal channel which passes right through 76. The channel 76 can come opposite any of the longitudinal channels 67 to 70 when the control part of fluid flow 73 rotates. The channel 76 opens into a receiving chamber 77 which is closed by a closure plate 78 which is sealed at an external radial wall of the cylindrical body 60 and which is sealed relative to the control part 73. The chamber 77 is filled with fluid and this chamber 77 communicates with an outlet 3 provided, for example, through part 78.

The operation of this device is as follows. The fluid arrives at the device through an inlet channel 80 so as to be brought into the interspire channel 8 located in the vicinity of one end of the wound wire 4. The control piece 73 is positioned in rotation in a certain position of desired control for which its distribution channel 77 is facing and in fluid communication with any one of the longitudinal channels 67 to 70, for example with the channel 67, as shown in the figure. It is therefore understood that, depending on the rotational position of the fluid flow control part 73, the path traveled by the fluid in the interspire space varies between a minimum path which separates the channel 65 from the channel 80 and a maximum path separating channel 62 from channel 80.

If it is desired that a fluid flow rate is always possible whatever the rotational position of the fluid flow control part 73, a recess 81 can be made in the radial surface of the part 82 which is opposite the radial surface 71 of the cylindrical body 60, as can be seen in FIGS. 7 and 8. This recess 81 can preferably extend so as to occupy all the space which separates any two adjacent longitudinal channels 62 to 65, such that so that the distribution channel 76 is always in fluid communication with at least one of the longitudinal channels 62 to 65. An important characteristic resides in the presence, at each longitudinal channel 67 to 70, of a seal sealing 88 which is housed in one. recess 89 concentric with the longitudinal channel 67 to 70, so that this seal 88 constitutes a seal between parts 60 and 73 so that the fluid passes without leakage from the channel (67 to 73) to channel 76. The internal diameter of the seal 88 is preferably equal to the diameter of the channel 67 to 70, and this seal 88 is preferably a slightly compressed O-ring when parts 60 and 73 are in contact with each other. The parts 60 and 73 can remain pushed towards each other by means of a compression spring (not shown) housed between the parts 78 and 73.

It can be seen that the particular design of the fluid flow control device according to the invention advantageously makes it possible to constitute an apparatus which has the advantageous characteristic of being able to both control an extremely low fluid flow, in a particularly reliable, precise manner. , stable and low cost, and to ensure that the device can also be controlled at will so as to be able to vary at will this fluid flow rate. An extremely efficient valve is therefore produced which can be controlled at will in a completely closed position and a completely open position, any intermediate positions determining a fluid flow rate that is both very low, very precise and determined completely freely. The device is also easily removable and cleanable. In particular, the wire 4 and the smooth surface on which the contiguous turns of the wire 4 can be applied to form the channel can be very easily cleaned. The wire and the piece with a smooth surface can be made of any material, for example, the wire can easily be made of polytetrafluorethyfene, nylon, gold, etc. and the piece with smooth surface can be easily made of stainless steel, metal covered with a veneer, etc. These embodiments are particularly economical and reliable because, in the field of mechanical construction, it is found that the easiest surfaces to be produced economically and reliably are the plane surfaces, the cylindrical surfaces and the surfaces of the fine wires. great length and constant section along the length. Figures 5 and 6 show two alternative embodiments of the apparatus as regards the means for applying pressure to the deformable part 5. In Figure 5, there is provided a sealed outer casing 83 which forms an annular chamber around the deformable part 5, this chamber being in fluid communication with the fluid inlet 2 via a channel 84. Thus, the fluid inlet pressure provides the force for applying the deformable part 5 against the wire 4.

In FIG. 6, there is provided a cap of slightly conical internal shape 85, one end 86 of which is screwed onto a central end portion of the body 60. Two half-shells 87 having an internal cylindrical surface and an external conical surface are interposed between the part 85 and the deformable part 5. By thus screwing the cap 85, the two half-shells 87 are brought together towards the central axis and consequently the compression of the deformable part which therefore comes to bear against the wire 4.

In a variant (not shown) with respect to the embodiment of FIG. 5 or 6, instead of having a single wound wire 4, a plurality of wound wires can be successively arranged, separately from each other. A channel then connects each adjacent wound wire to each other. Depending on the radial channel which is in fluid communication with the outlet, the fluid passes through a certain number of wound wires, this number varying between the unit and the maximum number of wound wires which is provided. This makes it possible to be able to increase the adjustment range of the fluid flow rate because it is possible to provide different characteristics for the different wound wires. For example, the first wound wire may have a large diameter and the successive wound wires may have diameters which gradually decrease. In this way, it is possible to constitute an apparatus for controlling the flow of fluid controllable at will in which the characteristic of the flow of fluid as a function of the angular position of the control piece of fluid flow can constitute a curve. any, for example an exponential or logarithmic curve. Throughout the text, the term “wire” therefore means a single wire or a plurality of wires connected together by fluid communication passages. FIG. 9 schematically represents an example of a combined apparatus which can be envisaged from the fluid flow control device according to the present invention. This device, which also constitutes an element in itself of the present invention, consists of a fluid flow control device according to the invention 90 with which is associated a closed tank 91 containing a certain finite quantity of a fluid and comprising, in a manner known per se, a means of constant pressurization 92. The means 92 may consist of a flexible wall 93 which separates a chamber 94 containing the fluid and a chamber 95 containing a fluid having two liquid-gas phases, this fluid can for example be freon. The two-phase fluid gradually expands at constant pressure by pushing the membrane 93 so as to expel the fluid contained in the chamber 94, this fluid being maintained under constant pressure, so that the fluid passes through the control device of fluid flow 90 and comes out at a constant flow rate at outlet 96. This device can for example make it possible to deliver a medicament in the human body, this medicament having to be delivered continuously and at an extremely low flow rate and very precise. It can therefore be seen that one of the particularly advantageous applications of a fluid flow control device according to the present invention relates to the medical field and more particularly to the field of continuous injection of drugs into the human body.

It is also possible, without departing from the scope of the invention, to constitute devices (FIG. 10) combining a micropump 97 and a fluid flow control device 90 according to the present invention. We can also consider combining a micropump 97, an expansion bladder 98 for damping fluctuations in the output flow of the micropump and a fluid flow control device 90 according to the present invention.

We can also consider, as shown in Figure 1 1, to design a syringe 99 to which is coupled at the outlet a fluid flow control device 90 via a bladder or expansion piece 100 which serves to keep the pressure supplied by the actuating force of the syringe 99 substantially constant. This assembly which also constitutes an apparatus according to the present invention can advantageously make it possible to constitute a new syringe making it possible to deliver a fluid, for example a medicament, according to a fluid flow controlled so as to be relatively low and precise. Figure 12 shows an alternative embodiment of the device shown in Figure 1 1. In this variant, the bladder 100 is eliminated and instead it is provided inside the syringe 99 to accommodate in the fluid contained in the syringe an elastic body with closed pores 101 which can contract under the action of the pressure. Thus, the syringe is formed in a simpler manner but it functions in a manner identical to that of the syringe shown in FIG. 11.

The invention can be applied in a large number of fields, for example in the field of automatic watering or automatic plant treatment. In this case, a fluid flow control device according to the invention can be connected to a circuit for supplying water or chemicals for cultivation. The device is preferably placed near the plant to be watered or treated. The extremely simple, reliable and economical construction possibilities which result from the characteristics of the present invention make it possible to envisage such applications in a realistic manner.

Claims

1. Device for restricting a flow of a fluid which passes through said device by entering the device by a fluid inlet (2) and leaving the device by a fluid outlet (3), characterized in that said device comprises: a rigid body (1, 20, 30, 50, 60) having a smooth surface (9, 21, 31, 66); a fluid inlet conduit (7, 23, 42, 57; 62-65) which is in communication with said fluid inlet (2) and which opens at said smooth surface in a first place; a fluid outlet conduit (10, 24, 44, 58, 80) which is in communication with said fluid outlet (3) and which opens at said smooth surface at a second location distant from the first location; and a wire (4, 32) wound in such a way as to form contiguous turns and so that all the turns are applied against said smooth surface of said rigid body, from which it follows that a channel (8) is thus formed which is limited by said smooth surface, by any whorl and by a whorl adjoining any whorl, so that said channel (8) has a reduced cross-sectional area and a length close to the length of the wire (4, 32 ); and in that said first location is located in the vicinity of a first end of the wire so that the incoming fluid arrives in said channel (8) in the vicinity of this first end of the wire and said second location is located in the vicinity of the other end of the wire so that the outgoing fluid comes from said channel in the vicinity of this other end of the wire, from which it follows that the fluid successively passes through the fluid inlet conduit, the channel and the conduit fluid outlet and is restricted in flow through the channel (8).

2. Device according to claim 1, characterized in that said smooth surface of said rigid body is a cylindrical surface (9, 21, 66) and in that said wire is helically wound (4) against this smooth cylindrical surface so as to form a plurality of turns (4A, 4B) which are contiguous and which are applied against the smooth cylindrical surface.

3. Device according to claim 2, characterized in that it further comprises: an elastic piece (5, 22, 33) of generally cylindrical shape comprising a first cylindrical surface which is applied with a certain force against the side of the coiled wire helically (4) which is opposite to said smooth surface; and pressure applying means (6, 83, 85) which applies a certain pressure radially to the other cylindrical surface of said elastic piece to provide said force with which the first cylindrical surface of the elastic piece is applied against the helically wound wire (4).

4. Device according to claim 3, characterized in that said means for applying pressure is constituted by a rigid part of revolution (85) having a surface of revolution whose dimensions are slightly in interference with the dimensions of said first surface of the elastic piece in order to compress this elastic piece to create said force with which the cylindrical surface of the elastic piece is applied against the helically wound wire.

5. Device according to claim 3, characterized in that said means for applying pressure is constituted by a closed chamber (83A) of generally annular and cylindrical shape which is limited: by said other surface of the elastic part and by a surface of a tight rigid body (83) which communicates with the fluid which enters or leaves said device, so that the pressure of the fluid which thus fills this chamber supplies the pressure of said pressure applying means.

6. Device according to claim 1, characterized in that said smooth surface of said rigid body is a flat surface (31) in that said wire is wound in a spiral (32) against this flat fissed surface so as to form a plurality of turns which are contiguous and which are applied against the flat smooth surface.

7. Device according to claim 6, characterized in that it further comprises: an elastic piece (33) having the general shape of a disc, comprising a flat surface which is applied with a certain force against the wire wound in a spiral (32); and pressure applying means (30, 37, 38, 39) which applies pressure to said elastic piece to provide said force with which the planar surface of the elastic piece is pressed against the wire.

8. Device according to claim 7, characterized in that said means for applying pressure is constituted by a rigid part which has the general shape of a disc (30) and which is constantly pushed against said elastic part ( 33) in order to compress this elastic piece to create said force with which the surface of the elastic piece is applied against the wire.

9. Device according to claim 7, characterized in that said means for applying pressure is constituted by a closed chamber having a general shape of a disc which communicates with the fluid which enters or leaves said device, such so that the pressure of the fluid thereby filling this chamber supplies the pressure of said pressure applying means.

10. Device according to any one of the preceding claims, characterized in that it further comprises a movable part (50, 73) which makes it possible to establish a communication of fluid direct between said fluid inlet (2) or said fluid outlet (3) and an area of said smooth surface (9, 31) of said rigid body so that this area can move on said smooth surface so as to vary the effective length of said channel (8) to vary accordingly the degree of restriction of the fluid flow rate.