Diaphragm-piston assembly for valve and manufacturing method

Abstract

To propose a novel piston-diaphragm assembly in which the risk of leakage at the internal annular ring of a diaphragm is reduced.SOLUTION: A stem (52) comprises a piston groove (58) with a groove proximal rim (56). A needle (90) is attached to a stem distal end (59). The assembly comprises a diaphragm (80), an internal annular ring (82) received in the piston groove (58) for attaching the diaphragm (80), and an annular membrane (83) connecting the annular ring. The needle (90) comprises a crown (93), in which the crown (93) surrounds the stem (52) and externally covers the internal annular ring (82) and the crown includes a crown rim (95), which terminates the crown (93) at the groove proximal rim (56). The diaphragm (80) is radially interposed between the groove proximal rim (56) and the crown rim (95) and is in contact with the crown rim (95).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a piston-diaphragm assembly, a valve including such an assembly, and a method of manufacturing such an assembly. [Background technology]

[0002] US Pat. No. 5,399,633 describes a sprayer for spraying a coating product, which comprises a base with an internal passage into which inlet and outlet conduits for the coating product open. A seat is formed in the internal passage at the opening of the outlet passage. A valve is mounted in the internal passage and closed with respect to the outside, whereby a coating product chamber is bounded by the valve and the internal passage, into which the inlet and outlet conduits open. The valve comprises a valve body, by means of which the valve is mounted on the base, a stem translatable in the valve body, and a needle mounted at the end of the stem. Depending on the position of the stem, the needle presses against the seat to close the outlet passage or leaves the seat to not close the outlet passage. To prevent the coating material in the coating material chamber from rising along the stem through the valve body, the valve has a membrane, sometimes called a diaphragm, surrounding the stem, which is fixed to the valve body by an O-ring and to the stem by another O-ring, with an elastically deformable web being arranged between the rings.

[0003] While such types of valves are generally satisfactory for handling coating products or other pressurized fluids, a common failure is the leakage of pressurized fluid at the ring that attaches the diaphragm to the stem, under the effect of the progressive accumulation of fluid residues between the diaphragm and the needle, which tends to deform or damage the ring. In fact, the elastic deformation of the diaphragm during use of the valve can accidentally open a gap between the diaphragm and the needle. The open gap can then allow debris to get in between the diaphragm and the needle, which can keep the gap open and allow more debris to accumulate at said location, until the ring is sufficiently deformed or damaged to cause leakage of pressurized fluid. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] FR3108378A1 Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE DISCLOSURE The object of the present invention is therefore to propose a novel piston diaphragm assembly in which the risk of leakage at the internal annular ring of the diaphragm is reduced. [Means for solving the problem]

[0006] To that end, the subject of the invention is a piston diaphragm assembly for a valve, comprising a piston including a stem extending parallel to the distal direction, the stem intended to be received in a central conduit of the body of the valve in a sliding manner with respect to the body parallel to the distal direction, the stem surrounding the stem and comprising a piston groove opening radially outward, the piston groove comprising a groove proximal rim and a groove distal rim delimiting the piston groove, the groove distal rim being offset along the distal direction with respect to the groove proximal rim. The piston comprises a needle belonging to the stem, fixed to the stem distal end and configured to abut against a blocking seat along the distal direction to block the pressurized fluid conduit. The assembly comprises a diaphragm with a peripheral annular ring surrounding the piston for mounting the diaphragm to the valve body, an internal annular ring surrounding the piston and received in the piston groove, thereby mounting the diaphragm to the piston, and an annular membrane connecting the peripheral annular ring to the internal annular ring.

[0007] The needle comprises a crown that surrounds the stem by externally covering an internal annular ring and has a crown rim that terminates the crown in a direction opposite the distal direction, the crown rim being disposed at the groove proximal rim, and the diaphragm being radially sandwiched between the groove proximal rim and the crown rim and in contact with the crown rim.

[0008] One of the ideas behind the present invention is to have the ring of the needles cover the inner annular ring over a large area, in order to prevent gaps between the diaphragm and the ring, more particularly regardless of the elastic deformation of the diaphragm caused by the pressurized fluid during the use of the valve. The crown of the needles covers the inner annular ring over a large area in that the crown rim is arranged at the height of the groove proximal rim. The needles advantageously cover the inner annular ring over its entire height, or even cover a part of the annular membrane, unlike the prior art, which provide no or only a small coverage of the inner annular ring by the needles.

[0009] According to further advantageous aspects, the invention implements one or more of the following features, taken individually or according to all technically possible combinations:

[0010] Preferably, the crown includes a base adjacent the distal rim of the groove.

[0011] Preferably, the crown comprises an internal conical surface connecting the base to the crown rim and converging along the distal direction, the crown abutting obliquely against the diaphragm in a direction opposite the distal direction via the internal conical surface.

[0012] Preferably, the crown comprises an internal concave surface connecting the base to the crown rim and converging along the distal direction, the crown abutting obliquely against the internal annular ring in a direction opposite the distal direction via the internal concave surface.

[0013] Preferably, the interior comprises an internal chamfer that converges along the distal direction and abuts the groove distal rim.

[0014] Preferably, the needle comprises a proximal attachment contact surface forming an internal conduit, whereby the needle is preferentially secured to the stem by engaging the distal end of the shaft along the distal direction with the proximal fixation contact surface, with the crown extending from the proximal attachment contact surface in a direction opposite to the distal direction.

[0015] Preferably, the groove proximal rim is radially wider than the groove distal rim.

[0016] Preferably, the piston groove has a radial section, from the groove distal rim to the groove proximal rim, that takes the form of a portion of a circle.

[0017] A further subject of the invention is a valve, comprising a piston diaphragm assembly as defined above. The valve comprises a body having a central conduit coaxial with the central axial conduit and opening at a distal end of the body belonging to the body. The piston is slidable with respect to the body along the central axis between a distal position and a proximal position, the distal direction of the piston being parallel to the central axis. The stem is received within the central conduit and projects from the central conduit from the distal end of the body when the piston is in the distal position. The needle is arranged outside the central conduit and is offset along the distal direction from the distal end of the body regardless of whether the piston is in the proximal or distal position. A peripheral annular ring attaches the diaphragm to the distal end of the body. The diaphragm separates the central conduit from a pressurized fluid chamber separated beyond the diaphragm in a distal direction and is configured to be elastically deformed between an initial shape when the piston is in a distal position and no overpressure is generated in the pressurized fluid chamber relative to the central conduit and an extended shape under the effect of an overpressure being generated in the pressurized fluid chamber relative to the central conduit. The crown rim is in contact with the diaphragm whether the diaphragm is in the initial shape or one of the extended shapes and regardless of whether the piston is in a distal or proximal position.

[0018] A further subject of the invention is a manufacturing method for a piston diaphragm assembly as defined above, which includes fitting an inner tubular ring while the needle is not yet fixed on the stem, through the stem distal end until the inner annular ring is received in the piston groove to attach the diaphragm to the stem, and includes fixing the needle to the stem distal end while the inner annular ring is received in the piston groove, whereby the crown surrounds the stem by externally covering the inner annular ring, and whereby the diaphragm is radially sandwiched between the groove proximal rim and the crown rim and in contact with the crown rim.

[0019] Preferably, the method includes positioning a temporary cap on the stem distal end while the needle is not yet secured to the stem and the internal annular ring is not yet fitted to the stem, the temporary cap covering the stem distal end and the internal annular ring being fitted onto the stem via the temporary cap, the internal annular ring sliding along an outer tapered surface of the temporary cap, the outer tapered surfaces converging along a distal direction. Preferably, the method then includes removing the temporary cap while the internal annular ring is housed in the groove piston and prior to securing the needle to the stem distal end.

[0020] The invention will be clearer after reading the following description, given by way of example only and not by way of limitation, with reference to the drawings in which: [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a longitudinal cross-sectional view of a pressurized fluid device including a valve with a piston in a distal position and a diaphragm in an initial shape. [Diagram 2] FIG. 2 is a view similar to FIG. 1 with the piston in a distal position and the diaphragm in a distally extended configuration. [Diagram 3] FIG. 3 is an enlarged view of the detail shown in FIG. 2. [Figure 4]3 is a view similar to FIGS. 1 and 2 with the piston in a proximal position and the diaphragm in a proximal extended configuration; FIG. [Diagram 5] 5 is a view similar to that of FIGS. 1, 2 and 4 showing steps in a method of manufacturing a piston diaphragm assembly belonging to a valve; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Figures 1 to 4 show a part of a device for applying a coating product. Such an apparatus is, for example, a sprayer for paints, varnishes, anticorrosive coatings or other types of coating products that may be envisaged. This apparatus is a particular type of pressurized fluid apparatus that uses at least two pressurized fluids, namely the coating product or other products used in the context of coating, such as a solvent or a component of the coating product, and a control fluid, such as compressed air. The coating product is a pressurized fluid in that it is used in the apparatus under a pressure ranging from 1 to 16 bar, preferably from 2 to 10 bar. The above also applies in the case of the solvent or a component of the coating product. The control fluid is a pressurized fluid in that it is used in the apparatus under a pressure ranging from 1 to 10 bar, preferably from 2 to 6 bar.

[0023] The apparatus comprises a valve 3. The valve 3 is particularly suitable for installation in an apparatus for applying a coating product as described herein, but may be used with other types of pressurized fluid devices, such as pneumatic or hydraulic devices, that use one or more pressurized fluids other than those described herein. In the present example, the valve 3 is intended to selectively block the pressurized fluid, which is the coating product, and allow the pressurized fluid to flow. In the other aforementioned cases of application of the valve 3, a particular pressurized fluid may be replaced with another fluid.

[0024] The base 2 belonging to the device or valve 3 forms a bore 20 and two pressurized fluid conduits, including an inlet conduit 21 for the coating product and a discharge conduit 22 for the coating product. The conduits 21 and 22 open into the bore 20. The bore 20 opens to the outside 24 of the device, i.e. advantageously it is open to the atmosphere. The valve 3 is fixed and accommodated in the bore 20 by blocking it. The valve 3 and the bore 20 define a common central axis X3. The central axis X3 passes through the bore 20 from its opening to its bottom. In the case of the present invention, the discharge conduit 22 is centered on the axis X3. A distal direction X50 is also defined, oriented parallel to the axis X3, towards the bottom of the bore 20. Unless otherwise indicated, words such as "distal", "proximal", "radial" and "axial" are indicated with reference to the axis X3 and the direction X50.

[0025] Conduits 21 and 22 open into a zone of bore 20 that delimits pressurized fluid chamber 25, here the coating product. A blocking seat 27 is formed at the opening of conduit 22 into chamber 25, here coaxial with axis X3. As shown in Fig. 4, a pressurized fluid flow F21, here the coating product, is intended to circulate successively through conduit 21, chamber 25 and conduit 22, via seat 27, when valve 3 is in the open configuration. As shown in Figs. 1 to 3, when valve 3 is in the closed configuration, flow F21 is blocked by valve 3, which blocks seat 27.

[0026] A control fluid conduit (not shown) opens into a zone of the bore 20 that separates chamber 25 from a chamber 26, referred to as the "peripheral control chamber", which extends between the opening of the bore 20 to the exterior 24. A flow of control fluid circulates between the control fluid conduit and the peripheral control chamber 26 to mechanically control the valve 3. The control fluid may be pressurized air.

[0027] The valve 3 comprises a body 30. A central axis X3 is fixed with respect to the body 30. Along the axis X3, the body 30 has a distal end 31, referred to as the "distal body end", and a proximal end 32, referred to as the "proximal body end", which are opposed and traversed by the axis X3.

[0028] The valve 3 is received and mounted in the bore 20 by means of a body 30. For mounting in the bore 20, the body 30 advantageously comprises an external thread 34, here centred on the axis X3, or any other suitable mounting means, which cooperates with a mating mounting means belonging to the base 2, here an internal thread which mates with the external thread 34, formed inside the bore 20 near the opening. In the example, the thread 34 is arranged on the inside of the proximal end 32.

[0029] When accommodated within the bore 20 , the valve 3 thereby delimits, together with the bore 20 , a pressurized fluid chamber 25 at the bottom of the bore 20 along a distal direction X 50 relative to the valve 3 .

[0030] Body proximal end 32 is disposed toward the exterior 24 at the opening of bore 20. A control chamber 26 is radially bounded between body 30 and bore 20 of base 2. A peripheral chamber 28, preferably referred to as the "vent chamber", is radially bounded between body 30 and bore 20 of base 2 and axially bounded between chamber 25 and chamber 26. More specifically, a screw thread 34 is disposed between proximal end 32 and control chamber 26.

[0031] Body 30 defines a central conduit 33 that is coaxial with and traversed by axis X3 throughout its length. Conduit 33 passes through body 30 from one side to the other. Central conduit 33 opens at body distal end 31 and at body proximal end 32.

[0032] At the body distal end 31, the central conduit 33 defines a conduit distal end 36 which terminates the central conduit 33 and opens at the body distal end 31. Starting from the conduit distal end 36 in a direction opposite to the distal direction X50, the central conduit 33 runs continuously along an axis X3, advantageously delimiting, inside the body 30, an intermediate chamber 37, a control chamber 38 and a proximal chamber 39. The chambers 37, 38 and 39 are traversed by the axis X3.

[0033] The valve 3 further comprises a piston 50 .

[0034] The piston 50 is accommodated in the central conduit 33 and is configured to slide relative to the body 30 along an axis X3, and is guided to do so by the central conduit 33. The piston 50 slides between a distal position, which is a closed position, by which the valve 3 is obtained in a closed configuration shown in Figs. 1 to 3, and a proximal position, which is an open position, by which the valve 3 is obtained in an open configuration shown in Fig. 4. In the distal position, the piston 50 is offset along a direction X50 with respect to the proximal position. In said position, the piston 50 protrudes from the central conduit 33, from the conduit distal end 36 and thus from the body distal end 31, into the chamber 25 along the direction X50.

[0035] The valve 3 further includes a diaphragm 80. The diaphragm 80 is an elastically deformable component, unlike other components such as the piston 50 and the main body 30, which are rigid bodies.

[0036] The diaphragm 80 comprises a peripheral ring 81 surrounding the piston 50 for mounting the diaphragm 80 to the body distal end 31. The diaphragm 80 comprises an inner annular ring 82 mounting the diaphragm 80 to the piston 50 and surrounding the piston 50. The diaphragm 80 includes an annular membrane 83 radially connecting the peripheral annular ring 81 to the inner annular ring 82, forming a continuous surface all around the piston 50. The diaphragm 80, and in particular the diaphragm 80 using the membrane 83, is thereby delimited beyond the diaphragm 80 along the direction X3, separating the central conduit 33 from the pressurized fluid chamber 25. The rings 81 and 82 are preferentially both centered on the axis X3. Each ring 81 and 82 preferentially has a circular shape around the axis X3 and extends in a respective plane perpendicular to the axis X3. Ring 82 is attached to piston 50 so as to be movable simultaneously with piston 50, while ring 81 is attached to body 30 so as to be fixed regardless of the position of piston 50. Membrane 83 elastically deforms to always connect rings 81 and 82, regardless of the position of piston 50 relative to body 30.

[0037] The diaphragm 80 has a geometry of revolution about the axis X3, ie it has a radial or near-radial cross section which is advantageously the same all around the axis X3.

[0038] The diaphragm 80 extends through an inner annular ring 82 and is traversed by the piston 50 which projects into the chamber 25. The diaphragm 80 and the bottom of the bore 20 together define the chamber 25. In other words, the diaphragm 80 bounds the chamber 25. The diaphragm 80 provides a dynamic seal against pressurized fluid around the piston 50 between the chamber 25 and the body distal end 31, more particularly between the chamber 25 and the central conduit 33. Preferably, it is also the diaphragm 80 which blocks the bore 20 around the body 30, facing the outside 24, as will be explained in more detail below.

[0039] Preferably, the body distal end 31 forms an annular cradle 43 and, preferentially, a body groove 40. The annular cradle 43 is formed around the conduit distal end 36. The body groove 40 is formed around the cradle 43 and thus also around the conduit distal end 36. The groove 40 extends over the body 30 around the axis X3 in a plane perpendicular to the axis X3. The groove 40 bounds and delimits the cradle 43 over its entire circumference. Preferably, the body groove 40 is open towards the outside.

[0040] Advantageously, the peripheral annular ring 81 is installed to be received in the body groove 40 and is securely positioned on the body part 30. Preferably, the ring 81 is held in a slightly deformed state by the body groove 40, in that the body groove 40 presses the ring 81 radially outwardly with respect to the central axis X3. The ring 81 is thereby held in a deformed state, the ring 81 being elastically stretched radially outwardly with respect to the central axis X3. In the undeformed state, the ring 81 preferentially has a circular radial section, i.e. is toroidal in shape. In the deformed state shown in Figs. 1 to 4, the ring 81 is preferentially slightly flattened by the body groove 40 for the part of the peripheral annular ring 81 against which the body groove 40 abuts radially outwardly. The ring 81 is thereby slightly held on the body part by the groove 40, particularly during assembly when the body part 30 is not yet received in the bore 20.

[0041] Preferably, the peripheral annular ring 81 is radially sandwiched between the body 30 and the bore 20 to attach the peripheral annular ring 81 to the body 30 while delimiting the chamber 25 so as to be sealed against the coating product. The ring 81 thereby separates the chamber 25 from the remainder of the bore 20 and is held in the groove 40 by the bore 20. The pressurized fluid present in the chamber 25 cannot then leak along the body 30 to the outside 24. More specifically, the bore 20 comprises an internal conical surface 29 centered on the axis X3 and converging along a direction X50. The surface 29 abuts obliquely against the peripheral annular ring 81 along the axis X3 in a direction opposite to the direction X50. The ring 81 is thereby radially sandwiched between the surface 29 and the groove 40 to seal the chamber 25. More specifically, the ring 81 fluidly separates the chamber 25 from the vent chamber 28, which are adjacent to said ring 81. The ring 81 thus prevents leakage of the coating product from the chamber 25 towards the vent chamber 28 or even towards the control chamber 26. In one variant, it is provided that it is not the ring 81 that ensures the sealing, but a static seal, distinct from a diaphragm, which is radially sandwiched between the body 30 and the bore 20.

[0042] Preferably, to facilitate the installation of the ring 81 within the body groove 40, the body groove 40 is open not only outwardly but also along the distal direction X50. Nevertheless, the ring 81 is fixed in place within the groove 40 by means of the abutment of the bore 20 against the ring 81.

[0043] More specifically, as can be seen more clearly in FIG. 3, the body groove 40 comprises a groove proximal rim 41 and a groove distal rim 42 that delimit the body groove 40. The rim 41 forms a circular protruding rim extending about the axis X3 in a plane perpendicular to the axis X3. The rim 42 is offset along a direction X50 with respect to the rim 41. The rim 42 forms a circular protruding rim extending about the axis X3 in a plane perpendicular to the axis X3. The rim 42 marks the boundary between the groove 40 and the annular cradle 43. The rim 41 has a larger diameter than the rim 42, which is arranged along a direction X50 with respect to the rim 41. Preferably, the groove 40 has a radial profile that starts from the rim 42, is first parallel or nearly parallel to the axis X3, and then rotates outward to the rim 41. In other words, the groove 40 is recessed in the direction opposite the distal direction X50, but is not recessed radially inward or is only slightly recessed, which facilitates insertion of the ring 81 into the groove 40 in the direction opposite the distal direction X50.

[0044] To delimit the control chamber 26 in a sealed manner against the control fluid, the valve 3 advantageously includes a stationary seal 72 and a stationary seal 73, for example an O-ring. The chamber 26 is axially delimited by the seals 72 and 73 and extends axially between the seals 72 and 73. Each seal 72 and 73 surrounds the body 30 around its entire periphery around the axis X3. Each seal 72 and 73 is sandwiched between the body 30 and the bore 20 in a radial direction with respect to the axis X3. More specifically, the seal 72 is axially arranged between the ring 81 and the seal 73. The chamber 26 and the vent chamber 28 are adjacent to the seal 72, which fluidically separates the chamber 26 from the vent chamber 28 and prevents the control fluid coming from the chamber 26 from leaking into the vent chamber 28, or even into the chamber 25, by flowing along the body 30. The seal 73 separates the chamber 26 from the opening of the bore 20. The seal 73 thus prevents leakage of control fluid from the chamber 26 towards the threads 34 or even towards the outside 24 .

[0045] The annular cradle 43 of the body 30 extends radially between the central conduit 33 and the peripheral annular ring 81, more particularly between the body groove 40 and the conduit distal end 36. More particularly, the cradle 43 is delimited internally by the conduit distal end 36 and externally by the groove distal rim 42. The annular cradle 43 advantageously has a shape that rotates around the axis X3. Preferably, the annular cradle 43 has a rounded radial section that is recessed in the direction opposite to the direction X50. More precisely, the rounded radial section has a hollow curvature without ripples. More generally, as shown in the figures, the annular cradle 43 is recessed towards the annular membrane 83. Preferably, the end 36 that forms a circular rim that bounds the cradle 43 from the inside is arranged along the direction X50 with respect to the rim 42 that bounds the cradle 43 from the outside. The rim 42 advantageously has a larger diameter than the end 36. A rounded radial section connects the end 36 to the rim 42 .

[0046] The piston 50 includes a stem 52 and a needle 90 .

[0047] The stem 52 extends parallel to the direction X50 and is coaxial with the axis X3. The stem is housed in the central conduit 33. More specifically, the stem 52 projects into the chamber 25 and then continues to extend through the conduit distal end 36 and the intermediate chamber 37 to emerge in the control chamber 38. Preferably, the piston 50 is guided in sliding by radial sliding of the stem 52 along the wall of the intermediate chamber 37. In other words, the piston 50 is guided in sliding with the stem 52 by the central conduit 33 of the body 30.

[0048] The stem 52 includes, successively along the direction X50, a portion 51, a piston groove 58, and a stem distal end 59.

[0049] Advantageously, portion 51 is arranged to cooperate with conduit 33, whereby stem 52 guides the sliding of piston 50. In the distal position of piston 50 as shown in Figures 1 to 3, portion 51 projects from conduit 33 along direction X50, i.e. extends beyond ends 31 and 36. In the proximal position of piston 50, as shown in Figure 4, portion 51 is preferably totally, or almost totally, retracted inside conduit 33.

[0050] The piston groove 58 is arranged to be outside the central conduit 33 whatever the position of the piston 50. The piston groove 58 surrounds the stem 52 all around the circumference about the central axis X3 and opens radially outwardly with respect to the central axis X3. The piston groove 58 advantageously extends along a plane perpendicular to the axis X3.

[0051] As can be seen more clearly in FIG. 3, the piston groove 58 comprises a groove proximal rim 56 and a groove distal rim 57, between which the piston groove 58 is delimited. The rim 57 is offset along the direction X50 with respect to the rim 56. The rim 56 advantageously forms a circular protruding rim extending around the axis X3 in a plane perpendicular to the axis X3. The rim 56 preferentially has a radial profile with a rounded fillet so as not to be cut. The rim 56 marks the boundary between the groove 58 and the portion 51. The rim 57 is offset along the direction X50 with respect to the rim 56. The rim 57 forms a circular protruding rim extending around the axis X3 in a plane perpendicular to the axis X3. The rim 57 marks the boundary between the groove 58 and the stem distal end 59. Preferably, the piston groove 58 has a radial section from the rim 56 to the rim 57 that is recessed and takes the form of a part of a circle. In other words, the groove 58 presents a toroidal shaped portion about the axis X3.

[0052] For the diaphragm 80 to be mounted on the piston 50, the inner annular ring 82 is received in the piston groove 58. Preferably, the ring 82 is held in a slightly deformed state by the piston groove 58 in such a way that the piston groove 58 presses the ring 82 radially outwardly with respect to the central axis X3. The ring 82 is thereby held in a deformed state, the ring 82 being elastically stretched radially outwardly with respect to the central axis X3. In the undeformed state, the ring 82 has a tilted, elliptical radial section that preferentially converges along the direction X50. In the deformed state shown in Figures 1 to 4, the ring 82 is preferentially rounded by the piston groove 58 for the part of the annular ring 82 against which the groove 58 abuts radially outwardly. The ring 82 is thereby mounted on the stem 52 by the groove 58, particularly during assembly when the needle 90 is not yet mounted in the stem 52.

[0053] Advantageously, groove proximal rim 56 is arranged to be radially wider than groove distal rim 57, which facilitates mounting of retaining ring 82 to stem 52 by engagement via distal end 59 in a direction opposite direction X50, as described below. However, unlike groove 40, groove 58 is advantageously arranged to be radially inwardly recessed, such that ring 82 is attached to the stem by groove 58 even when needle 90 is not yet in place.

[0054] The membrane 83 has a constant thickness or exhibits a slight variation from ring 81 to ring 82. The diaphragm 80, and in particular the membrane 83, is configured to be elastically deformed in response to the current position of the piston 50 with respect to the central conduit 33 and the occurrence of an overpressure of the pressurized fluid in the chamber 25. Preferably, the membrane 83 has a shape that rotates about the axis X3.

[0055] "Occurrence of overpressure" means that pressurized fluid 25 is present in chamber 25, in particular in central conduit 33, at a pressure having a value higher than the pressure of the fluid, which may be air, present on the other side of diaphragm 80. In such a case, the difference in value between the pressure of the pressurized fluid in chamber 25 and the pressure of the pressurized fluid in conduit 33 is greater than a certain pressure difference threshold that is not negligible. When the difference in value between the pressure of the pressurized fluid in chamber 25 and the pressure of the pressurized fluid in conduit 33 is less than a given pressure difference threshold that has a tendency towards zero, there is considered to be no overpressure.

[0056] More specifically, when no overpressure occurs in the chamber 25 with respect to the central conduit 33 and the piston is in the distal position, the diaphragm 80 assumes an initial shape, shown in FIG. 1. This initial shape may be considered as the rest position of the diaphragm 80, towards which it naturally returns due to its elasticity when the pressures in the chamber 25 and the conduit 33 are close or of the same value. In the initial shape, the annular membrane 83 is spaced apart from the cradle 43, preferably over the entire surface of the annular membrane 83. Preferably, the annular membrane 83 is also spaced apart from the stem 52, in particular from the portion 51 of the stem 52. Where appropriate, the membrane 83 contacts the stem only at the rim 56 and the cradle 43 only at the rim 42. This provides an annular volume between the annular membrane 83 and the cradle 43, and between the rim 42 and the rim 56. In its initial shape, as shown in FIG. 1, the membrane 83 has a curved, generally flared or conical shape, preferably without any undulations, if appropriate along the direction of the cradle 43.

[0057] As shown in Figures 2 to 4, when an overpressure occurs in the chamber 25 with respect to the conduit 33, the diaphragm 80 is elastically deformed towards an extended shape. Depending on the circumstances, in particular depending on the position of the piston 50, the extended shape may be different. In all possible extended shapes, the annular membrane 83, under the effect of the overpressure, comes into contact with and engages with the annular cradle 43, which presses the annular membrane 83 against the annular cradle 43. By engaging with the cradle 43, the membrane 83 assumes a shape that corresponds to the shape of the cradle. In order to assume one of the extended shapes, a sufficiently strong overpressure is required to elastically deform the membrane 83 until it abuts against the annular cradle 43 in the direction opposite to the direction X50. The cradle 43 thereby abuts the membrane 83 in the direction opposite to the direction X50, which holds the membrane 83 against the effect of the overpressure, so that the membrane 83 is not overstretched. This prevents degradation of the membrane in the event of excessive overpressure. Furthermore, the shape of the cradle 43 ensures that as the membrane 83 mates with the cradle 43, the membrane 83 is precisely deformed according to the desired shape imparted by the cradle 43. This further reduces the risk of deterioration to the membrane 83.

[0058] The diaphragm 80 can be elastically deformed towards a particular extended shape, called the "distal extended shape", not only when an overpressure occurs in the chamber 25, but also when the piston 50 is in a distal position, which is shown in Figures 2 and 3. In the distal extended shape, only the proximal portion 86 of the membrane 83 contacts and fits with the cradle 43, while the distal portion 87 contacts and fits with the stem 52 against the portion 51 protruding from the end 36 of the conduit 33. Given a distal position of the piston 50, the portion 51 then extends axially between the annular cradle 43, more particularly the end 36, and the inner annular ring 82, more particularly the groove 58.

[0059] More specifically, the proximal portion 86 has an annular shape and extends from the ring 81 to the distal portion 87. The distal portion 87 has an annular shape and extends from the proximal portion to the ring 82. Preferably, the distal portion 87 and the proximal portion 86 each occupy about half the surface area of ​​the membrane 83. Preferably, substantially the entirety of the distal portion 87 is in contact with the portion 51 of the stem 52. Preferably, substantially the entirety of the proximal portion 86 is in contact with the cradle 43. Similarly, substantially the entirety of the cradle 43, from the rim 42 to the end 36, is in contact with the membrane 83. Similarly, substantially the entirety of the portion 51 of the stem 52 emerging from the conduit 33, from the end 36 to the rim 56, is in contact with the membrane 83. Where appropriate, the part of the membrane 83 located at the boundary between the distal portion 87 and the proximal portion 86 is not pressed against the cradle 43 or the stem 52 at the end 36.

[0060] The fact that the membrane 83 engages both with the portion 51 of the stem 52 and with the cradle 43 in the above described situation results in a reduced risk of degradation of the membrane 83 .

[0061] The diaphragm 80 can be elastically deformed towards a particular extended shape, called the "proximal extended shape", not only when an overpressure occurs in the chamber 25, but also when the piston 50 is in a proximal position, which is shown in FIG. 4. In such a case, the portion 51 of the stem 52 is retracted inside the conduit 33. Preferably, in such a case, the membrane 83 is in almost the entirety in contact with the cradle 43. Similarly, almost the entirety of the cradle 43, from the rim 42 to the end 36, is in contact with the membrane 83. More specifically, both the proximal portion 86 and the distal portion 87 are preferentially in almost the entirety in contact with the cradle 43. The fact that the membrane 83 is in almost the entirety engaged with the cradle 43 under such circumstances results in a reduced risk of degradation of the membrane 83.

[0062] In its initial shape, it is preferred that the annular membrane 83 is convex towards the annular cradle 43, i.e. has a curvature with its underside directed towards the annular cradle 43, as shown in Figure 1. This initial curvature ensures that the membrane 83 will assume the other shapes described above when an overpressure occurs. Advantageously, when the diaphragm 80 is in its initial shape, none of the portions 86 and 87 are in contact with the cradle 43 and the stem 52, except where appropriate with the rims 42 and 56.

[0063] Preferably, the installation is such that in all shapes that the diaphragm 80 may assume during the use of the valve, or at least in the stretched shape, advantageously no surface of the annular membrane 83 comes into contact with another surface of the annular membrane 83. In other words, the annular membrane 83 does not fold until it comes into contact with itself, which makes it possible to reduce the risk of deterioration of the membrane 83. More generally, the installation can be such that no folds of the membrane 83 occur due to the initial and stretched shapes mentioned above, by pressing the membrane 83 against the cradle 43, especially against the stretched shape, the shape of the cradle 43 being particularly configured to prevent sharp folding of the membrane 83.

[0064] In the absence of overpressure and while the piston 50 is in the proximal position, the membrane 83 advantageously assumes the same shape as the proximal extended shape. However, arrangements can be made such that the membrane 83 assumes a different intermediate shape, in particular such that the membrane 83 does not completely contact the cradle 43.

[0065] Further other stretched shapes may be obtained when overpressure occurs and the piston 50 is in an intermediate position between the distal and proximal positions. Moreover, in all intermediate situations, where either the overpressure is too low or the piston 50 is not in the distal position, or both, the diaphragm 80 may assume a respective intermediate shape that is neither the initial shape nor any of the stretched shapes as described above.

[0066] Regardless of whether the piston 50 is in the proximal or distal position, the needle 90 is preferably arranged to be entirely outside the central conduit 33, in the chamber 25, offset along the distal direction X50 with respect to the body distal end 31. The needle 90 is attached to the stem 52 by the stem distal end 59. The needle 90 is a distinct part of the stem 52 and is attached to the stem 52 by being attached directly to the stem 52. The stem distal end 59 starts from the piston groove 58 and is arranged along the direction X50, advantageously coaxial with the axis X3. In the proximal position of the piston 50, the needle 90 is away from the seat 27, allowing the flow F21 to circulate, and in the distal position of the piston 50, it abuts axially against the seat 27, blocking the conduit 22 and preventing the flow F21 from circulating.

[0067] More particularly, needle 90 advantageously includes a blocking distal end 91, a proximal mounting contact surface 92, and a crown 93, which together advantageously form a unitary molded piece.

[0068] The needle 90 is attached to the stem distal end 59 by a proximal attachment contact surface 92. Preferably, the proximal attachment contact surface 92 takes the form of an internal conduit centered on the axis X3, opening in the direction opposite the distal direction X50 and receiving therein the stem distal end 59 sleeved along the distal direction X50. Preferably, the attachment is obtained by forcibly sleeve the needle 90 onto the stem 52, more particularly the contact surface 92 onto the distal end 59. As shown in the figures, advantageously, the distal end 59 is provided with claws arranged around the end 59, radially embedded in the contact surface 92 and holding the needle 90 in the direction opposite the distal direction X50. In a variant, instead of sleeve the needle 90 onto the stem distal end 59, it is also possible to screw the needle 90 onto the stem distal end 59. The proximal mounting contact surface 92 then has female threads and the stem distal end 59 has matching male threads to allow for tightening of the screw.

[0069] The blocking end 91 extends from the contact surface 92 and the end 59 along the distal direction. The blocking end 91 preferentially has a convex shape or takes the form of a plug along the direction X50. When the stem 52 is in the distal position as shown in Figs. 1 to 3, the end 91 abuts against the blocking sheet 27 along the distal direction X50, thereby blocking the blocking sheet 27. The conduit 22 is then fluidly isolated from the chamber 25, preventing the establishment of the flow F21. When the stem 52 is in the proximal position as shown in Fig. 4, the end 91 retracts with respect to the blocking sheet 27 in a direction opposite to the direction X50, thereby releasing the blocking sheet 27. The conduit 22 is then fluidly connected to the chamber 25, whereby the flow of the fluid F21 can be established.

[0070] A crown 93 is formed axially opposite the proximal or blocking end 91 of the needle 90. The bottom of the internal conduit of the contact surface 92 is disposed between the crown 93 and the end 91. The crown 93 surrounds the stem 52 around its entire periphery at the groove 58 and externally covers the inner annular ring 82, which is radially sandwiched between the crown 93 and the groove 58.

[0071] More specifically, crown 93 includes a base 94 and a crown rim 95. Preferably, crown 93 defines, on the interior side of crown 93, in sequence opposite distal direction X50, an internal chamfered surface 96, an internal concave curved surface 97, and an internal conical surface 98, as shown in FIG. 3. Surfaces 96, 97, and 98 together form a continuously flared inner wall that surrounds stem 52.

[0072] The base 94 advantageously begins at the proximal end of the contact surface 92. In other words, the crown 93 extends in a direction opposite the direction X50 from an internal conduit formed by the contact surface 92. A crown rim 95, which is arranged in a direction opposite the distal direction X50 with respect to the base 94, advantageously forms the proximal end of the needle 90 and the crown 93.

[0073] The base 94 connects the crown 93 to the blocking distal end 91 and starts at the proximal end of the contact surface 92. The base 94, having an annular shape, surrounds the stem 52. In the direction opposite to the direction X50, the base 94 starts adjacent to the groove distal rim 57 and extends radially outward from the stem 52 in the direction opposite to the direction X50 to a crown rim 95, which terminates the crown 93 in the direction opposite to the direction X50 and is radially away from the stem 52. The crown rim 95, which is preferably circular, spans over the stem 52 in a plane perpendicular to the axis X3. The crown rim 95 is arranged at the height of the groove proximal rim 56, i.e. at the same level as the proximal groove rim 56 along the axis X3, or even beyond the proximal groove rim 56 in the direction opposite to the direction X50. This causes the crown 93 to completely cover the groove 58 such that the crown 93 begins at the distal rim 57 adjacent the distal rim 57 and extends radially a distance from the groove 58 .

[0074] The internal chamfer 96 converges along the distal direction X50 and abuts the groove distal rim 57. The chamfer 96 serves to prevent a cut rim from forming at the interface between the needle 90 and the stem 52, thereby avoiding the risk of deterioration of the ring 82 during use.

[0075] An internal concave surface 97 of the rounded hollow shape connects the base 94 to the crown rim 95, and more particularly connects the chamfered surface 96 to the internal conical surface 98. The surface 97 begins at the chamfered surface 96 such that the groove distal rim 57 is offset along the direction X50 relative to the beginning of the surface 97. The internal concave surface 97 converges along the distal direction X50.

[0076] An internal conical surface 98 connects the base 94 to the crown rim 95, and more particularly connects the internal concave surface 97 to the crown rim 95. The surfaces 98 converge along the distal direction X50.

[0077] The inner annular ring 82 is received in the groove 58 so that it is sandwiched between the crown 93 and the stem 52 in a radial direction with respect to the axis X3 and is in contact with the crown 93, preferentially over its entire height or over a large part of its height. More specifically, the ring 82 is in contact with the surfaces 97 and 98. The crown 93 abuts obliquely against the inner annular ring 82 via the internal concave surface 97 in a direction opposite the distal direction X50. The oblique abutment allows the retaining ring 82 to be held by the needle 90 in the groove 58, whereby the retaining ring 82 is held attached to the stem 52. The crown 93 abuts obliquely against the diaphragm 80, more specifically against the ring 82, via the internal conical surface 98 in a direction opposite the distal direction X50. This helps to hold the retaining ring 82 in the groove 58.

[0078] A distal portion 87 of membrane 83, by which membrane 83 is attached to retaining ring 82, is sandwiched radially with respect to axis X3 between groove proximal rim 56 and crown rim 95 by contacting crown rim 95. More generally, diaphragm 80 is sandwiched radially between groove proximal rim 56 and crown rim 95 and is in contact with crown rim 95.

[0079] In other words, the diaphragm 80 abuts the crown 93 over the entire surface of the diaphragm 80 that is radially sandwiched between the crown 93 and the stem 52, particularly at the crown rim 95 and, if appropriate, away from the distal end of the ring 82 at the rim 57. Preferentially, the crown rim 95 is kept in contact with the diaphragm 80, regardless of whether the diaphragm 80 is in its initial shape, in one of its stretched shapes, or in another shape during use. Preferably, the crown rim 95 is kept in contact with the diaphragm 80, regardless of whether the piston 50 is in its distal position, in its proximal position, or in any other intermediate position. Maintaining support between the crown rim 95 and the diaphragm 80 over the entire circumference of the axis X3 prevents the opening of an annular gap between the diaphragm 80 and the needle 90, which avoids the insertion and accumulation of residue or other material between the diaphragm 80 and the crown 93. To maintain contact between crown rim 95 and diaphragm 80 in all such circumstances, provision is made such that when needle 90 is installed, crown 93 presses against diaphragm 80, exerting a force in a direction opposite to direction X50 to maintain diaphragm 80 in an elastically deformed configuration compressing diaphragm 80 in a direction opposite to direction X50. More specifically, provision is made such that ring 82 and portion 87 of membrane 83 are maintained in an elastically deformed state by obliquely abutting surfaces 96 and 97 and rim 95 against ring 82 and portion 87 of membrane 83.

[0080] Preferably, the stem 52 comprises a proximal base 53 and a collar flange 55 at a proximal end of the stem 52 opposite the portion 51 and the needle 90. Between the base 53 and the collar flange 55 on the one hand, and between the portion 51 and the needle 90 on the other hand, the stem 52 passes through the intermediate chamber 37 and the control chamber 38 of the central conduit 33. The collar flange 55 separates the control chamber 38 from the proximal chamber 39. The proximal base 53, formed at the proximal end of the piston 50, faces the needle 90. The proximal base 53 is arranged within the proximal chamber 39.

[0081] The valve 3 advantageously comprises a spring 54 which exerts an elastic return force on the piston 50, here via the proximal base 53, bearing against the body part 30. This elastic return force tends to move the piston 50 along the direction X50 from its proximal position to its distal position. Preferably, the spring 54 is arranged inside the body 30, here in the proximal chamber 39 around the piston 50.

[0082] The control chamber 26, delimited by the base 2, is fluidly connected to a control chamber 38 formed inside the body 30. For this purpose, the body 30 forms one or more conduits (not shown) that connect the chambers 26 and 38 when the body 30 is mounted on the base 2. Thus, the control fluid penetrates into the control chambers 26 and 38, thereby exerting pressure on the collar flange 55 by pressurizing the chamber 38, which tends to move the piston 50 from the distal position to the proximal position against the force generated by the spring 54. Applying pressure by pressurizing the control fluid brings the piston 50 to the proximal position, and releasing the pressure by lowering the control fluid pressure allows the spring 54 to return the piston 50 to the distal position. This allows the opening and closing of the valve 3 to be controlled.

[0083] Similar to peripheral chamber 28, intermediate chamber 37 also forms a vent chamber. Preferably, peripheral chamber 28 is fluidly connected to intermediate chamber 37 by one or more conduits formed in body portion 30, such that chambers 28 and 37 together form a vent chamber. In the event of failure of one of the seals or ring 81, pressurized or control fluid can leak through the failed seal towards chambers 28 and 37, preventing penetration into the remainder of valve 3.

[0084] The piston 50 and the diaphragm 80 may be considered as a group as a piston diaphragm assembly belonging to the valve 3. During the manufacture of the valve 3, the piston diaphragm assembly is preferentially installed in the body 30, in which the ring 82 is already housed in the groove 58 of the stem 52 and the needle 90 is already attached to the stem 52. The above involves inserting the piston 50 into the central conduit 33 and then installing the ring 81 in the groove 40. The body 30 is then installed in the bore 20 of the base 2. Similarly, for maintenance, the piston diaphragm assembly may be replaced in its entirety by removing the worn piston diaphragm assembly as a unit from the body 30 and then reassembling a repaired or new piston diaphragm assembly as a unit in the body 30.

[0085] To manufacture the piston diaphragm assembly, a manufacturing method is used that includes several steps, which are described below.

[0086] Initially, the stem 52, needle 90 and diaphragm 80 are provided in a configuration in which these portions are spaced apart from one another.

[0087] 5, the method advantageously then includes positioning a temporary cap 100 over the stem distal end 59. At this stage, the needle 90 has not yet been attached to the stem 52, and the inner annular ring 82 of the diaphragm 80 has not yet been fitted onto the stem 52.

[0088] The temporary cap 100 advantageously comprises a proximal base 102, by means of which the cap 100 is attached to the stem distal end 59. Preferably, the proximal base 102 comprises a bore opening in a direction opposite to the direction X50 for receiving the end 59. The proximal base 102 preferably covers the end 59 entirely, in particular by covering any tabs provided, if appropriate, on the end 59. Preferably, the base 102 extends up to the distal rim 57 of the groove 58 when the cap 100 is positioned. Externally, the base 102 preferably has a cylindrical shape with a circular base, centred on the axis X3.

[0089] The temporary cap 100 comprises a distal end 101, advantageously centred on the axis X3, having a tapered shape along a distal direction X50, the tip of which is advantageously rounded. Preferably, the end 101 forms an external tapered surface 103, here conical. The surface 103 converges along the distal direction X50. The end 101 converges along the direction X50. The end 101 continues uninterruptedly with the external shape of the base 102, so that seen from the outside, the cap 100 tapers overall, for example in a cylindrical-conical general shape.

[0090] The method then includes fitting the inner annular ring 82 onto the stem 52, but with the needle 90 not yet mounted on the stem and the cap 100 in place on the stem 52. The inner annular ring 82 is fitted through the distal end 59 such that the inner annular ring 82 is received within the piston groove 58 to attach the diaphragm 80 to the stem 52. With the cap 100 in place, fitting the inner annular ring 82 onto the stem 52 is performed with the temporary cap 100, the inner annular ring 82 sliding along the outer tapered surface 103 of the temporary cap in a direction opposite to the direction X50. The use of cap 100 facilitates fitting of ring 82 because ring 82 can be easily traversed by the pointed end of temporary cap 100, then gradually resiliently released as it moves gradually along outer tapered surface 103, and finally resiliently returned to a tighter shape after cap 100 has been threaded through, seating in groove 58. Cap 100 also advantageously prevents a pawl supported by end 59 from potentially damaging ring 82.

[0091] The method then includes removing the temporary cap 100 while the inner annular ring 82 is received within the groove 58 and prior to attaching the needle 90 to the stem distal end 59 .

[0092] The method then includes mounting the needle 90 on the stem distal end 59 with the temporary cap 100 removed while the inner annular ring 82 is received in the groove 58. For this purpose, the needle 90 is sleeved onto the stem 52 by forcefully sleeve the proximal mounting contact surface 92 onto the stem end 59 in a direction opposite to the direction X50. A tab on the stem end 59, if provided, then prevents retraction of the needle 90. The needle 90 is mounted in such a manner that the crown 93 surrounds the stem 52 by externally covering the inner annular ring 82, so that the base 94 is adjacent the groove distal rim 57 and the diaphragm 80 is radially sandwiched between the groove proximal rim 56 and the crown rim 95, and is in contact with the crown rim 95, as previously described.

[0093] Features described above for one of the embodiments or one of the variations can also be used for the other embodiments and variations described above, insofar as technically possible. [Explanation of symbols]

[0094] F21 Pressurized Fluid Flow X3 common center axis X50 Distal 2 base 3 Valve 20 Bore 21 Inlet conduit 22 Release conduit 24 Outside 25 Pressurized Fluid Chamber 26 Chamber 27 Blocking Sheet 28 Peripheral Chamber 29 Inner Cone Surface 30 Main body 31 Distal end of main body 32 Proximal end 33 Central conduit 34 threads 36 Distal end of conduit 37 Intermediate Chamber 38 Control Chamber 39 Proximal Chamber 40 Body groove 42 Rims 43 Circular Cradle 50 Piston 51 parts 52 Stem 53 Proximal base 54 Spring 55 Color flange 56 groove proximal rim 57 groove distal rim 58 Piston groove 59 Distal end of stem 72 Fixed seal 73 Fixed seal 80 Diaphragm 81 Peripheral Ring 82 Inner Annular Ring 83 Annular membrane 86 Proximal part 87 Distal part 90 Needle 91 Distal cut-off end 92 Proximal Attachment Contact Surface 93 Crown 94 Base 95 Crown Rim 96 Internal chamfer 97 Internal concave curved surface 98 Internal Cone Surface 100 Temporary Cap 101 Distal end 102 Base 103 External tapered surface

Claims

1. A piston diaphragm assembly for a valve (3), comprising: A piston (50), a stem (52) extending parallel to a distal direction (X50), the stem (52) intended to be received in a central conduit (33) of a body (30) of the valve (3) in a sliding manner with respect to the body (30) parallel to the distal direction (X50), the stem (52) comprising a piston groove (58) surrounding the stem (52) and opening radially outwardly, the piston groove (58) comprising a groove proximal rim (56) and a groove distal rim (57) delimiting the piston groove (58), the groove distal rim (57) being offset from the groove proximal rim (56) in the distal direction (X50); a piston (50) belonging to said stem (52) and comprising a needle (90) fixed to a stem distal end (59) and configured to abut against a blocking sheet (27) along said distal direction (X50) to block a pressurized fluid conduit (22); A diaphragm (80), a peripheral annular ring (81) for fixing the diaphragm (80) to the body (30) of the valve (3), the peripheral annular ring (81) surrounding the piston (50); an inner annular ring (82) surrounding the piston (50) and received within the piston groove (58), thereby attaching the diaphragm (80) to the piston (50); a diaphragm (80) comprising an annular membrane (83) connecting said peripheral annular ring (81) to said inner annular ring (82); 11. A piston diaphragm assembly comprising: a needle (90) having a crown (93) surrounding the stem (52) and externally covering an inner annular ring (82); the crown (93) having a crown rim (95) terminating the crown (93) in a direction opposite to the distal direction (X50); the crown rim (95) being arranged at the height of the groove proximal rim (56); and the diaphragm (80) being radially sandwiched between the groove proximal rim (56) and the crown rim (95) and in contact with the crown rim (95).

2. The piston diaphragm assembly of claim 1 , wherein the crown comprises a base (94) adjacent the groove distal rim (57).

3. 3. The piston diaphragm assembly of claim 2, wherein the crown (93) comprises an internal conical surface (98) connecting the base (94) to the crown rim (95) and converging along the distal direction (X50), and the crown (93) abuts obliquely against the diaphragm (80) via the internal conical surface (98) in a direction opposite to the distal direction (X50).

4. 3. The piston diaphragm assembly of claim 2, wherein the crown (93) comprises an internal concave curved surface (97) connecting the base (94) to the crown rim (95) and converging along the distal direction (X50), and the crown (93) abuts obliquely against the internal annular ring (82) via the internal concave curved surface (97) in a direction opposite to the distal direction (X50).

5. 3. The piston diaphragm assembly of claim 2, wherein said crown (93) comprises an internal chamfered surface (96) converging along said distal direction (X50) and adjacent said groove distal rim (57).

6. 6. A piston diaphragm assembly as claimed in any one of claims 1 to 5, wherein the needle (90) has a proximal mounting contact surface (92) forming an internal conduit through which the needle (90) passes when secured to the stem (52), and the crown (93) extends from the proximal mounting contact surface (92) in a direction opposite to the distal direction (X50).

7. 7. The piston diaphragm assembly of claim 6, wherein the needle (90) is fixed to the stem (52) by engaging the stem distal end (59) with the proximal mounting contact surface (92) along the distal direction (X50).

8. 6. A piston diaphragm assembly as claimed in any one of claims 1 to 5, wherein the groove proximal rim (56) is radially wider than the groove distal rim (57).

9. 6. The piston diaphragm assembly of claim 1, wherein the piston groove (58) has a radial section, from the groove distal rim (57) to the groove proximal rim (56), in the shape of a portion of a circle.

10. A valve (3) comprising a piston diaphragm assembly according to any one of claims 1 to 5, The valve (3) comprises a body (30) having a central conduit (33) coaxial with a central axis (X3) and opening at a distal end (31) of the body belonging to the body (30); the piston (50) is slidable relative to the body portion (30) along the central axis (X3) between a distal position and a proximal position, the distal direction (X50) of the piston (50) being parallel to the central axis (X3); the stem (52) is received within the central conduit (33) and projects from the central conduit (33) from the distal end (31) of the body when the piston (50) is in the distal position; the needle (90) is arranged outside the central conduit (33) and is offset in the distal direction (X50) from the distal end (31) of the body, regardless of whether the piston (50) is in the proximal or distal position; the peripheral annular ring (81) attaches the diaphragm (80) to the distal end (31) of the body; the diaphragm (80) separates the central conduit (33) from a pressurized fluid chamber (25) bounded beyond the diaphragm (80) in the distal direction (X50); an initial shape when the piston (50) is in the distal position and no overpressure is generated in the pressurized fluid chamber (25) with respect to the central conduit (33); configured to be elastically deformed between an extended configuration under the effect of an overpressure generated in the pressurized fluid chamber relative to the central conduit (33); The crown rim (95) is in contact with the diaphragm (80) regardless of whether the diaphragm (80) is in an initial shape or one of an extended shape and whether the piston (50) is in a distal or proximal position, a valve (3).

11. A method for manufacturing a piston diaphragm assembly according to any one of claims 1 to 5, comprising the steps of: while the needle (90) is not yet secured on the stem (52), fitting the inner annular snap ring (82) to the stem (52), the inner annular ring (82) being fitted through the stem distal end (59) until the inner annular ring (82) is received in the piston groove (58) to attach the diaphragm (80) to the stem (52); securing the needle (90) to the stem distal end (59) while the inner annular ring (82) is received in the piston groove (58); the crown (93) surrounds the stem (52) by externally covering the inner annular ring (82); and causing the diaphragm (80) to be radially sandwiched between the groove-proximal rim (56) and the crown rim (95) by contacting the crown rim (95).

12. positioning a temporary cap on the stem distal end (59) while the needle (90) is not yet fixed to the stem (52) and the inner annular ring (82) is not yet fitted to the stem (52), the temporary cap covering the stem distal end (59) and the inner annular ring (82) fitting onto the stem (52) via the temporary cap, the inner annular ring (82) sliding along an outer tapered surface of the temporary cap, the outer tapered surface converging along the distal direction (X50); and removing the temporary cap while the inner annular ring (82) is received within the grooved piston (58) and prior to securing the needle (90) to the stem distal end (59).

Images