Piston-diaphragm assembly for valve and method of manufacturing same

Abstract

A piston-diaphragm assembly for a valve and a method of manufacturing the same. A piston-diaphragm assembly for a valve (3) has a piston (50) comprising a rod (52) and a needle (90). The rod (52) includes a piston groove (58) having a piston groove proximal edge (56). A needle (90) is attached to the shaft distal end (59). The assembly comprises a diaphragm (80) having: a peripheral loop (81); an inner ring (82) housed in the piston groove (58) for attaching the diaphragm (80) to the piston; and an annular membrane (83) connecting the loops. The needle (90) includes a coronal portion (93) surrounding the rod (52) and externally covering the inner ring (82), the coronal portion including a coronal edge (95) terminating the coronal portion (93) at a piston groove proximal edge (56). A diaphragm (80) is radially interposed between and in contact with the piston groove proximal edge (56) and the crown edge (95).

Description

Technical Field

[0001] The present invention relates to a piston-diaphragm assembly, a valve comprising such an assembly and a method for manufacturing such an assembly. Background Art

[0002] Document FR3108378A1 describes a sprayer for spraying a coating product, comprising a base having an internal passage, into which an input pipe and an output pipe for the coating product are passed. A seat is formed in the internal passage at the outlet of the output pipe. The valve is installed in the internal passage so as to close the passage relative to the outside, so that the coating product chamber is defined by the valve and the internal passage, into which the input pipe and the output pipe are passed. The valve comprises a valve body, a rod that can be translated in the valve body, and a needle attached to the end of the rod, and the valve is attached to the base through the valve body. Depending on the position of the rod, the needle can be against the seat to close the output pipe, or it can be away from the seat to not close the output pipe. To prevent the coating material in the coating material chamber from rising along the rod through the valve body, the valve has a membrane, which is sometimes called a diaphragm, surrounding the rod, fixed to the valve body by an O-ring and fixed to the rod by another O-ring, and an elastically deformable sheet is deployed between these rings.

[0003] Even though this type of valve is generally satisfactory for handling paint products or other pressurized fluids, a common malfunction is that leakage of the pressurized fluid occurs at the collar that attaches the diaphragm to the stem, due to the gradual accumulation of fluid residues between the diaphragm and the needle, which tends to deform or damage the collar. In fact, during use of the valve, a gap may accidentally open between the diaphragm and the needle through elastic deformation of the diaphragm. The open gap then allows debris to enter between the diaphragm and the needle, which keeps the gap open and allows more debris to accumulate in this location until the collar is sufficiently deformed or damaged to produce a pressurized fluid leak. Summary of the invention

[0004] The object of the present invention is to propose a novel piston-diaphragm assembly, for which the risk of leakage at the inner ring of the diaphragm is reduced.

[0005] To this end, the subject of the invention is a piston-diaphragm assembly for a valve. The assembly comprises a piston, the piston comprising: a rod extending parallel to a distal direction, the rod being intended to be received in a central conduit of the valve body in a manner that is slidable relative to the valve body in parallel to the distal direction, the rod comprising a piston groove surrounding the rod, the piston groove opening radially outward, the piston groove comprising a piston groove proximal edge and a piston groove distal edge, the piston groove being defined between the piston groove proximal edge and the piston groove distal edge, the piston groove distal edge being offset in the distal direction relative to the piston groove proximal edge. The piston also comprises a needle fastened to the distal end of the rod belonging to the rod, the needle being configured to abut against a shut-off seat in the distal direction to close a pressurized fluid conduit. The assembly also comprises a diaphragm, the diaphragm comprising: an outer ring for attaching the diaphragm to the valve body, the outer ring surrounding the piston; an inner ring surrounding the piston and received in the piston groove so as to thereby attach the diaphragm to the piston; and an annular membrane connecting the outer ring to the inner ring.

[0006] The needle includes a crown portion, which surrounds the rod and covers the inner ring from the outside. The crown portion includes a crown edge, which terminates the crown portion in a direction opposite to the distal direction. The crown edge is arranged at the proximal edge of the piston groove, and the diaphragm is radially interposed between the proximal edge of the piston groove and the crown edge and contacts the crown edge.

[0007] The idea behind the invention is to arrange the crown of the needle to cover a large area of ​​the inner ring to prevent the formation of a gap between the diaphragm and the crown of the needle, more specifically, to prevent the formation of a gap regardless of the elastic deformation of the diaphragm applied by the fluid under pressure during the use of the valve. The crown of the needle covers a large area of ​​the inner ring because the crown edge is arranged at the height of the proximal edge of the groove. The needle advantageously covers the inner ring over the entire height of the inner ring, or even covers a part of the annular membrane, which is different from the prior art, which does not provide coverage for the inner ring, or only provides edge coverage for the inner ring.

[0008] According to further advantageous aspects of the invention, the invention implements one or more of the following features, taken alone or in all technically possible combinations.

[0009] Preferably, the crown includes a base adjacent a distal edge of the piston groove.

[0010] Preferably, the crown portion comprises an inner conical surface connecting the base portion to the crown edge, the inner conical surface converges in the distal direction, and the crown portion is inclined against the septum in a direction opposite to the distal direction by the inner conical surface.

[0011] Preferably, the crown portion comprises a concave curved surface connecting the base portion to the crown edge, the concave curved surface converges in the distal direction, and the crown portion is inclined against the inner ring in a direction opposite to the distal direction by the concave curved surface.

[0012] Preferably, the crown portion comprises an inner bevel which converges in the distal direction and is adjacent to the distal edge of the piston groove.

[0013] Preferably, the needle comprises a proximal attachment interface forming an internal channel, the needle being fastened to the rod via the proximal attachment interface, preferably by fitting the distal end of the rod into the proximal attachment interface in a distal direction so that the needle is fastened to the rod, and the crown extends from the proximal attachment interface in a direction opposite to the distal direction.

[0014] Preferably, the proximal edge of the piston groove is radially wider than the distal edge of the piston groove.

[0015] Preferably, the piston groove has a radial section in the form of a portion of a circle from the piston groove distal edge to the piston groove proximal edge.

[0016] Another subject of the invention is a valve; the valve comprises a piston-diaphragm assembly as defined above. The valve comprises a valve body having a central conduit coaxial with the central axis, the central conduit opening at the distal end of the valve body belonging to the valve body. The piston can slide relative to the valve 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. A rod is housed in the central conduit, and when the piston is in the distal position, the rod extends from the central conduit from the distal end of the valve body. Regardless of whether the piston is in the proximal position or the distal position, the needle is arranged outside the central conduit, offset in the distal direction relative to the distal end of the valve body. A peripheral ring attaches the diaphragm to the distal end of the valve body. The diaphragm separates the central conduit from a pressurized fluid chamber, the pressurized fluid chamber being defined outside the diaphragm in the distal direction, the diaphragm being configured to deform elastically between the following shapes: an initial shape when the piston is in the distal position and no overpressure occurs in the pressurized fluid chamber relative to the central conduit; and a stretched shape under the effect of an overpressure occurring in the pressurized fluid chamber relative to the central conduit. The crown contacts the diaphragm whether the diaphragm is in one of the initial shape or the stretched shape and whether the piston is in the distal position or the proximal position.

[0017] Another subject of the invention is a manufacturing method for manufacturing a piston-diaphragm assembly as defined above. The method comprises: when the needle is not yet fastened to the rod, fitting the inner ring on the rod, the inner ring being fitted through the distal end of the rod until the inner ring is housed in the piston groove, so as to attach the diaphragm to the rod. The method comprises, when the inner ring is housed in the piston groove, fastening the needle to the distal end of the rod, so that the crown surrounds the rod, covers the inner ring from the outside, and so that the diaphragm is radially interposed between the proximal edge of the piston groove and the crown edge, contacting the crown edge.

[0018] Preferably, the method comprises positioning a temporary cap on the distal end of the rod, the temporary cap covering the distal end of the rod, while the needle has not yet been fastened to the rod and the inner ring has not yet been fitted to the rod, fitting the inner ring to the rod through the temporary cap by sliding the inner ring along an outer conical surface of the temporary cap, the outer conical surfaces converging in the distal direction. Preferably, the method then comprises removing the temporary cap before fastening the needle to the distal end of the rod, while the inner ring is housed in the piston groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention will become more apparent by reading the following description which is given by way of example only and not by way of limitation, and by referring to the accompanying drawings, in which:

[0020] Figure 1 is a longitudinal cross-sectional view of a pressurized fluid device including a valve having a piston and a diaphragm, wherein the piston is in a distal position and the diaphragm is in an initial shape;

[0021] Figure 2 is similar to Figure 1 , wherein the piston is in a distal position and the diaphragm is in a distal stretched shape;

[0022] Figure 3 yes Figure 2 an enlarged view of a detail shown;

[0023] Figure 4 is similar to Figure 1 and Figure 2 , wherein the piston is in a proximal position and the diaphragm is in a proximal stretched shape;

[0024] Figure 5 is similar to Figure 1 , 2 4 and 5 show a step in a method of manufacturing a piston-diaphragm assembly belonging to a valve. DETAILED DESCRIPTION

[0025] Figures 1 to 4 A portion of an apparatus for applying a coating product is shown. Such an apparatus is, for example, a sprayer for paint, varnish, anticorrosive coating or any other type of coating product that can be considered. The apparatus is a special type of pressurized fluid apparatus that uses at least two pressurized fluids, namely: a coating product or other product used in a spraying situation, such as a solvent or a coating product component; and a control fluid, such as compressed air. The coating product is a pressurized fluid because it is used in the apparatus at a pressure between 1 and 16 bar, preferably between 2 and 10 bar. The foregoing also applies to the case of a solvent or a coating product component. The control fluid is a pressurized fluid because it is used in the apparatus at a pressure between 1 and 10 bar, preferably between 2 and 6 bar.

[0026] The device includes a valve 3. The valve 3 is particularly suitable for installation in an apparatus for applying a coating product as described herein, but the valve can also be used with other types of pressurized fluid devices, such as pneumatic or hydraulic devices, using one or more pressurized fluids different from the pressurized fluids described herein. In this example, the valve 3 is intended to selectively interrupt and allow the flow of a pressurized fluid for a coating product. In other above-mentioned applications of the valve 3, a specific pressurized fluid can be replaced by another fluid.

[0027] The base 2 belonging to the device or valve 3 forms a channel 20 and two pressurized fluid conduits, which include an input conduit 21 for the coating product and a discharge conduit 22 for the coating product. The conduits 21 and 22 lead into the channel 20. The channel 20 leads to the outside 24 of the device, that is, the channel advantageously leads to the atmosphere. The valve 3 is fixedly accommodated in the channel 20, closing the channel 20. The valve 3 and the channel 20 define a common central axis X3. The central axis X3 passes through the channel 20 from the outlet of the channel 20 to the bottom. In this case, the discharge conduit 22 is centered on the axis X3. A distal direction X50 pointing toward the bottom of the channel 20 parallel to the axis X3 is also defined. Unless otherwise specified, terms such as "distal", "proximal", "radial" and "axial" are all referred to the axis X3 and the direction X50.

[0028] The pipes 21 and 22 open into a region of the bore 20 defining a chamber 25 for a pressurized fluid (here a coating product). At the outlet of the pipe 22 into the chamber 25, a shut-off seat 27 is formed here coaxially with the axis X3. Figure 4 As shown, when the valve 3 is in the open configuration, the pressurized fluid (here the coating product) flow F21 is intended to circulate in the conduit 21, the chamber 25 and the conduit 22 in sequence through the seat 27. Figures 1 to 3 In the closed configuration shown, the flow F21 is interrupted by the valve 3 closing the seat 27 .

[0029] A control fluid conduit (not shown) opens into a region of the bore 20 defining a chamber 26 called a "peripheral control chamber" extending between the chamber 25 and the outlet of the bore 20 to the exterior 24. A control fluid flow circulates between the control fluid conduit and the peripheral control chamber 26 to mechanically control the valve 3. The control fluid may be compressed air.

[0030] The valve 3 comprises a valve body 30. A central axis X3 is set relative to the valve body 30. Along the axis X3, the valve body 30 has a distal end 31 called "valve body distal end" and a proximal end 32 called "valve body proximal end", which are opposite and passed through by the axis X3.

[0031] The valve 3 is housed and attached in the bore 20 by means of a valve body 30. To attach to the bore 20, the valve body 30 advantageously comprises an external thread 34, here centered on the axis X3, or any other suitable attachment means, which cooperate with matching attachment means belonging to the base 2, here an internal thread matching the external thread 34, formed in the bore 20 close to the outlet. In this example, the thread 34 is arranged in the proximal end 32.

[0032] Thus, the valve 3 is housed in the bore 20 , the valve 3 together with the bore 20 defining a pressurized fluid chamber 25 at the bottom of the bore 20 in the distal direction X50 relative to the valve 3 .

[0033] The proximal end 32 of the valve body is arranged at the outlet of the bore 20, facing the exterior 24. The control chamber 26 is radially defined between the valve body 30 and the bore 20 of the base 2. Preferably, a peripheral chamber 28 called a "venting chamber" is defined radially between the valve body 30 and the bore 20 of the base 2, and axially between the chambers 25 and 26. More specifically, the thread 34 is arranged between the proximal end 32 and the control chamber 26.

[0034] The valve body 30 forms a central duct 33 coaxial with the axis X3 and traversed by the axis X3 over its entire length. The duct 33 extends through the valve body 30 from one side to the other. The central duct 33 is open at the valve body distal end 31 and the valve body proximal end 32.

[0035] At the valve body distal end 31, the central duct 33 defines a duct distal end 36 which terminates the central duct 33 and opens at the valve body distal end 31. In a direction opposite to the distal direction X50, starting from the duct distal end 36, the central duct 33 advantageously defines, in the valve body 30, an intermediate chamber 37, a control chamber 38 and a proximal chamber 39, successively along the axis X3. The axis X3 passes through these chambers 37, 38 and 39.

[0036] The valve 3 further comprises a piston 50 .

[0037] The piston 50 is accommodated in the central conduit 33 and is configured to slide relative to the valve body 30 along the axis X3, guided by the central conduit 33. The piston 50 slides between a distal position and a proximal position, the distal position being a closed position, so as to obtain Figures 1 to 3 The valve 3 is shown in a closed configuration, the proximal position being the open position, so as to obtain Figure 4 The open configuration of the valve 3 shown. In the distal position, the piston 50 is offset relative to the proximal position along the direction X50. In these positions, the piston 50 extends from the central conduit 33 along the direction X50 from the conduit distal end 36 and therefore from the valve body distal end 31 into the chamber 25.

[0038] The valve 3 further includes a diaphragm 80. Unlike other components such as the piston 50 and the valve body 30, which are rigid, the diaphragm 80 is an elastically deformable component.

[0039] The diaphragm 80 comprises a peripheral ring 81 for attaching the diaphragm 80 to the valve body distal end 31 and surrounding the piston 50. The diaphragm 80 also comprises an inner ring 82 for attaching the diaphragm 80 to the piston 50 and surrounding the piston 50. The diaphragm 80 comprises an annular membrane 83 which radially connects the peripheral ring 81 to the inner ring 82, thereby forming a continuous surface completely surrounding the piston 50. Thus, the diaphragm 80, in particular through the annular membrane 83, separates the central duct 33 from the pressurized fluid chamber 25 defined outside the diaphragm 80 along the direction X3. The rings 81 and 82 are preferably both centered on the axis X3. Each ring 81 and 82 preferably has a circular shape around the axis X3, extending in a corresponding plane perpendicular to the axis X3. The ring 82 is movable simultaneously with the piston 50 by being attached to the piston 50, while the ring 81 is fixed by being attached to the valve body 30 without being affected by the position of the piston 50. The membrane 83 deforms elastically so as to always connect the rings 81 and 82 regardless of the position of the piston 50 relative to the valve body 30 .

[0040] The diaphragm 80 has a geometry of revolution about the axis X3 , ie the diaphragm 80 advantageously has a radial cross section which is identical or approximate all around the axis X3 .

[0041] The piston 50 passes through the diaphragm 80, which extends through the inner ring 82 and protrudes into the chamber 25. The diaphragm 80 and the bottom of the channel 20 together define the chamber 25. In other words, the diaphragm 80 is adjacent to the chamber 25. The diaphragm 80 provides a dynamic seal for the pressurized fluid around the piston 50 between the chamber 25 and the valve body distal end 31, and more particularly between the chamber 25 and the central conduit 33. Preferably, it is also the diaphragm 80 that closes the channel 20 around the valve body 30 in the direction opposite to the exterior 24, as discussed in detail below.

[0042] Preferably, the valve body distal end 31 forms an annular bearing portion 43 and preferably also a valve body groove 40. The annular bearing portion 43 is formed around the pipe distal end 36. The valve body groove 40 is formed around the bearing portion 43 and therefore also around the pipe distal end 36. The groove 40 extends completely around the valve body 30 around the axis X3 in a plane perpendicular to the axis X3. The groove 40 adjoins the bearing portion 43 over the entire periphery of the bearing portion 43 to define the bearing portion 43. Preferably, the valve body groove 40 is open to the outside.

[0043] Advantageously, the peripheral ring 81 is arranged to be received in the valve body groove 40 so as to be securely positioned on the valve body 30. Preferably, the ring 81 is held in a slightly deformed state by the valve body groove 40, since the valve body groove 40 bears against the ring 81 radially outwardly relative to the central axis X3. Thus, the ring 81 is held in a deformed state, wherein the ring 81 is elastically stretched radially outwardly relative to the central axis X3. In the undeformed state, the ring 81 preferably has a circular radial cross section, i.e. is annular. Figures 1 to 4 In the deformed state shown, preferably, the portion of the peripheral ring 81 of the ring 81 which abuts radially outwards against the valve body groove 40 is slightly flattened by the valve body groove 40. Therefore, the ring 81 is slightly retained on the valve body by the groove 40, in particular during assembly, when the valve body 30 has not yet been accommodated in the bore 20.

[0044] Preferably, in order to attach the peripheral ring 81 to the valve body 30 while defining the chamber 25 to seal the coating product, the peripheral ring 81 is radially interposed between the valve body 30 and the channel 20. The ring 81 thus separates the chamber 25 from the rest of the channel 20 and is retained in the groove 40 by the channel 20. The pressurized fluid present in the chamber 25 cannot then escape to the exterior 24 along the valve body 30. More specifically, the channel 20 comprises an inner conical face 29 centered on the axis X3 and converging along the direction X50. The face 29 abuts against the peripheral ring 81 obliquely along the axis X3, in the direction opposite to the direction X50. Therefore, the ring 81 is radially interposed between the face 29 and the groove 40 to seal the chamber 25. More specifically, the ring 81 fluidically separates the chamber 25 from the vent chamber 28 adjacent to the ring 81. Thus, the collar 81 prevents the coating product from leaking from the chamber 25 into the ventilation chamber 28 or even into the control chamber 26. In a variant, it is provided that the seal is not ensured by the collar 81 but by a static seal distinct from the diaphragm and radially interposed between the valve body 30 and the orifice 20.

[0045] Preferably, to facilitate the installation of the ring 81 in the valve body groove 40 , the valve body groove 40 is open not only outwardly but also in the distal direction X50 . However, the ring 81 is held in place in the groove 40 by the bore 20 against the ring 81 .

[0046] In more detail, Figure 3As shown more clearly in FIG. 4 , the valve body groove 40 comprises a groove proximal edge 41 and a groove distal edge 42, between which the valve body groove 40 is defined. The edge 41 forms a circular protruding edge extending around the axis X3 in a plane perpendicular to the axis X3. The edge 42 is offset relative to the edge 41 in the direction X50. The edge 42 forms a circular protruding edge extending around the axis X3 in a plane perpendicular to the axis X3. The edge 42 marks the boundary between the groove 40 and the annular support portion 43. The diameter of the edge 41 is greater than the diameter of the edge 42, and the edge 42 is arranged relative to the edge 41 in the direction X50. Preferably, the groove 40 has a radial profile that is first parallel or almost parallel to the axis X3 starting from the edge 42 and then turns outward to the edge 41. In other words, the groove 40 is recessed in the direction opposite to the distal direction X50 without being recessed radially inward or slightly recessed, which facilitates the insertion of the ring 81 into the groove 40 in the direction opposite to the distal direction X50.

[0047] To define the control chamber 26 so that it is sealed from the control fluid, the valve 3 advantageously comprises a static seal 72 and a static seal 73, both of which are O-rings, for example. The chamber 26 is axially defined by the seals 72 and 73, extending axially between the seals 72 and 73. Each seal 72 and 73 surrounds the valve body 30 around the axis X3 over the entire periphery of the valve body 30. Each seal 72 and 73 is radially interposed between the valve body 30 and the bore 20 relative to the axis X3. More specifically, the seal 72 is axially arranged between the ring 81 and the seal 73. The seal 72 fluidically separates the chamber 26 from the vent chamber 28 adjacent to the seal 72 to prevent the control fluid from the chamber 26 from leaking into the vent chamber 28, or even into the chamber 25, by flowing along the valve body 30. The seal 73 separates the chamber 26 from the outlet of the bore 20. Thus, the seal 73 prevents the control fluid from leaking from the chamber 26 to the threads 34, or even to the exterior 24.

[0048] The annular support 43 of the valve body 30 extends radially between the central duct 33 and the peripheral ring 81, more specifically between the valve body groove 40 and the duct distal end 36. More precisely, the support 43 is delimited on the inside by the duct distal end 36 and on the outside by the groove distal edge 42. The annular support 43 advantageously has a shape of revolution about the axis X3. Preferably, the annular support 43 has a circular radial sector, which is recessed in the direction opposite to the direction X50. More precisely, the circular radial sector has a hollow curvature without any undulations. More generally, as shown, the annular support 43 is concave towards the annular membrane 83. Preferably, the distal end 36, which forms a circular edge adjoining the support 43 from the inside, is arranged in the direction X50 relative to the edge 42 adjoining the support 43 from the outside. The diameter of the edge 42 is advantageously greater than the diameter of the distal end 36. The circular radial sector connects the distal end 36 to the edge 42.

[0049] The piston 50 includes a rod 52 and a needle 90 .

[0050] The rod 52 extends parallel to the direction X50 and is coaxial with the axis X3. The rod is housed in the central conduit 33. More specifically, the rod 52 enters the chamber 25, then extends sequentially through the conduit distal end 36 and the intermediate chamber 37, and enters the control chamber 38. Preferably, the piston 50 is guided to slide by the radial sliding of the rod 52 along the wall of the intermediate chamber 37. In other words, the piston 50 is guided to slide by the central conduit 33 of the valve body 30 through the rod 52.

[0051] The rod 52 comprises, in sequence along the direction X50 , a portion 51 , a piston groove 58 and a rod distal end 59 .

[0052] Advantageously, portion 51 is arranged to cooperate with duct 33 so that rod 52 guides the sliding movement of piston 50. Figures 1 to 3 In the distal position of the piston 50 shown, the portion 51 extends from the conduit 33 in the direction X50, i.e., extends beyond the distal end 31 and the distal end 36. In the proximal position of the piston 50, as Figure 4 As shown, portion 51 is retracted into conduit 33, preferably completely or nearly completely.

[0053] Regardless of the position of the piston 50, the piston groove 58 is arranged to be located outside the central duct 33. The piston groove 58 surrounds the rod 52 around the central axis X3 around the entire periphery and opens radially outwards relative to the central axis X3. The piston groove 58 advantageously extends along a plane perpendicular to the axis X3.

[0054] like Figure 3 As shown more clearly, the piston groove 58 comprises a piston groove proximal edge 56 and a piston groove distal edge 57, between which the piston groove 58 is defined. The edge 57 is offset relative to the edge 56 in the direction X50. The edge 56 advantageously forms a circular protruding edge extending around the axis X3 along a plane perpendicular to the axis X3. The edge 56 preferably has a radial profile with rounded corners so as not to be sharp. The edge 56 marks the boundary between the piston groove 58 and the portion 51. The edge 57 is offset relative to the edge 56 in the direction X50. The edge 57 forms a circular protruding edge extending around the axis X3 along a plane perpendicular to the axis X3. The edge 57 marks the boundary between the piston groove 58 and the rod distal end 59. Preferably, the piston groove 58 has a radial section in the form of a portion of a circle that is concave from the edge 56 to the edge 57. In other words, the piston groove 58 describes an annular portion around the axis X3.

[0055] To attach the diaphragm 80 to the piston 50, the inner 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, since the piston groove 58 bears against the ring 82 radially outward relative to the center axis X3. Thus, the ring 82 is held in a deformed state, wherein the ring 82 is elastically stretched radially outward relative to the center axis X3. In the undeformed state, the ring 82 preferably has an elliptical radial cross section that converges obliquely in the direction X50. Figures 1 to 4 In the deformed state shown, the collar 82 is preferably rounded by the piston groove 58 for the portion of the collar 82 against which the groove 58 abuts radially outward. Thus, the collar 82 is attached to the rod 52 via the groove 58, particularly during assembly when the needle 90 is not yet attached to the rod 52.

[0056] Advantageously, the piston groove proximal edge 56 is radially wider than the piston groove distal edge 57, which facilitates mounting the retaining ring 82 on the rod 52 by assembly via the distal end 59 in a direction opposite to the direction X50, as described below. However, unlike the groove 40, it is advantageously provided that the groove 58 is recessed radially inwardly, so that the ring 82 is attached to the rod through the groove 58 even when the needle 90 is not yet in place.

[0057] The thickness of the membrane 83 is constant or slightly varies from the ring 81 to the ring 82. The membrane 80, and in particular the membrane 83, is configured to deform elastically as a function of the current position of the piston 50 and of the overpressure of the pressurized fluid in the chamber 25 relative to the central duct 33. Preferably, the membrane 83 has a shape of revolution about the axis X3.

[0058] "Overpressure occurs" means that there is a pressurized fluid 25 in the chamber 25, and its pressure value is greater than the pressure value of the fluid (which may be air) present on the other side of the diaphragm 80, in particular in the central conduit 33. In this case, the difference between the pressure of the pressurized fluid in the chamber 25 and in the conduit 33 is greater than a certain pressure difference threshold and is not negligible. When the difference between the pressure of the pressurized fluid in the chamber 25 and in the conduit 33 is less than a given pressure difference threshold and tends to zero, it is considered that there is no overpressure.

[0059] More specifically, when no overpressure occurs in the chamber 25 relative to the central conduit 33 and the piston is in the distal position, the diaphragm 80 assumes an initial shape, such as Figure 1As shown. The initial shape can be regarded as the rest position of the diaphragm 80, to which the diaphragm naturally returns by elasticity when the pressures in the chamber 25 and in the pipe 33 have close or identical values. In the initial shape, the annular membrane 83 is preferably away from the support part 43 over the entire surface of the annular membrane 83. Preferably, the annular membrane 83 is also away from the rod 52, in particular away from the portion 51 of the rod 52. If appropriate, the membrane 83 is in contact with the rod only at the edge 56 and with the support part 43 only at the edge 42. Therefore, an annular space is provided between the annular membrane 83 and the support part 43, and between the edges 42 and 56. In the initial shape, as Figure 1 As shown, the membrane 83 preferably has a substantially trumpet-shaped or conical shape, if appropriate concave in the direction of the support portion 43, preferably without any undulations.

[0060] like Figures 2 to 4 As shown, when an overpressure occurs in the chamber 25 relative to the pipe 33, the diaphragm 80 is elastically deformed towards the stretched shape. Depending on the situation, in particular, depending on the position of the piston 50, the stretched shape may be different. In all the stretched shapes that may be adopted, the annular membrane 83 contacts and cooperates with the annular support portion 43 under the action of the overpressure, and the overpressure presses the annular membrane 83 against the annular support portion 43. By cooperating with the support portion 43, the shape of the membrane 83 matches the shape of the support portion. To obtain one of the stretched shapes, the overpressure must be strong enough to elastically deform the membrane 83 until the membrane 83 abuts against the annular support portion 43 in the direction opposite to the direction X50. Since the support portion 43 thus abuts against the membrane 83 in the direction opposite to the direction X50, the support portion 43 resists the action of the overpressure and holds the membrane 83, so that the membrane 83 is not overstretched. The above-mentioned method can prevent the membrane from deteriorating under excessive overpressure. Furthermore, since the membrane 83 cooperates with the receiving portion 43, the shape of the receiving portion 43 ensures that the membrane 83 is deformed accurately according to the desired shape given by the receiving portion 43. The above-mentioned manner further reduces the risk of membrane 83 deterioration.

[0061] Not only when overpressure occurs in chamber 25, but also when piston 50 is in the distal position, diaphragm 80 can be oriented such as Figure 2 and Figure 3 The particular stretch shape shown, referred to as the "distal stretch shape," is elastically deformed. In the distal stretch shape, for the portion 51 extending from the distal end 36 of the conduit 33, only the proximal portion 86 of the membrane 83 contacts and cooperates with the bearing portion 43, while the distal portion 87 contacts and cooperates with the rod 52. Considering the distal position of the piston 50, the portion 51 then extends axially between the annular bearing portion 43 (more specifically the distal end 36) and the inner ring 82 (more specifically the piston groove 58).

[0062] In more detail, 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 represent about half of the surface area of ​​the membrane 83. Preferably, almost the entire distal portion 87 is in contact with the portion 51 of the rod 52. Preferably, almost the entire proximal portion 86 is in contact with the bearing portion 43. Similarly, almost the entire bearing portion 43 from the edge 42 to the distal end 36 is in contact with the membrane 83. Similarly, almost the entire portion 51 of the rod 52 extending from the pipe 33 from the distal end 36 to the edge 56 is in contact with the membrane 83. If appropriate, the portion of the membrane 83 located at the boundary between the distal portion 87 and the proximal portion 86 is not pressed against the bearing portion 43 or the rod 52 at the distal end 36.

[0063] In the above case, the fact that the membrane 83 cooperates both with the portion 51 of the rod 52 and with the receptacle 43 reduces the risk of degradation of the membrane 83 .

[0064] Not only when overpressure occurs in chamber 25, but also when piston 50 is in the proximal position, diaphragm 80 can be moved toward Figure 4 The particular stretched shape shown and referred to as the "proximal stretched shape" is elastically deformed. In this case, the portion 51 of the rod 52 is retracted into the conduit 33. Preferably, in this case, almost the entire membrane 83 is in contact with the support portion 43. Similarly, almost the entire support portion 43 from the edge 42 to the distal end 36 is in contact with the membrane 83. More specifically, both the proximal portion 86 and the distal portion 87 are in contact with the support portion 43, preferably almost completely. In this case, the fact that the membrane 83 is almost completely engaged with the support portion 43 reduces the risk of degradation of the membrane 83.

[0065] In the initial shape, the annular membrane 83 is preferably convex toward the annular support portion 43, that is, it has a curved portion with the back side facing the annular support portion 42, such as Figure 1 The initial bend ensures that when overpressure occurs, the membrane 83 will adopt the other shapes described above. Advantageously, when the membrane 80 is in the initial shape, the portions 86 and 87 are not in contact with the support 43 and the rod 52, except for the edges 42 and 56 as appropriate.

[0066] Preferably, in all the shapes that the diaphragm 80 may adopt during use of the valve, or at least for the stretched shape, it is advantageously provided that no surface of the annular membrane 83 is in contact with another surface of the annular membrane 83. In other words, the annular membrane 83 does not fold to the extent of coming into contact with itself, which allows reducing the risk of degradation of the membrane 83. More generally, it can be provided that, as a result of the above-mentioned initial shape and the stretched shape, no folding of the membrane 83 occurs, in particular by pressing the membrane 83 against the support 43 to obtain the stretched shape, the shape of the support 43 being specifically configured to prevent a sharp folding of the membrane 83.

[0067] In the absence of overpressure, when the piston 50 is in the proximal position, the membrane 83 advantageously adopts the same shape as the proximal stretched shape. However, it can be provided that the membrane 83 adopts different intermediate shapes, in particular wherein the membrane 83 is not in full contact with the bearing portion 43.

[0068] Other stretched shapes can still be obtained when overpressure occurs and the piston 50 is in an intermediate position between the distal position and the proximal position. In addition, in all intermediate situations where either the overpressure occurring is too low or the piston 50 is not in the distal position or both, the diaphragm 80 can adopt a corresponding intermediate shape that is neither the initial shape nor one of the stretched shapes described above.

[0069] Whether the piston 50 is in the proximal or distal position, the needle 90 is preferably arranged completely in the chamber 25, outside the central duct 33, offset in the distal direction X50 relative to the distal end 31 of the valve body. The needle 90 is attached to the rod 52 by the rod distal end 59. The needle 90 is a component distinct from the rod 52, attached to the rod 52 by being mounted directly on the rod 52. The rod distal end 59 starts from the piston groove 58 in 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 to allow the flow F21 to circulate, and in the distal position of the piston 50, the needle abuts axially against the seat 27 to close the duct 22 and prevent the flow F21 from circulating.

[0070] In more detail, the needle 90 advantageously comprises a shut-off distal end 91 , a proximal attachment hub 92 and a crown 93 , which together advantageously form a one-piece, unitary component.

[0071] The needle 90 is attached to the rod distal end 59 by a proximal attachment interface 92. Preferably, the proximal attachment interface 92 is in the form of an internal pipe centered on the axis X3, open in the direction opposite to the distal direction X50, and accommodates the rod distal end 59 sleeved along the distal direction X50. Preferably, this attachment is obtained by pressing the needle 90 onto the rod 52, more specifically, by pressing the interface 92 onto the rod distal end 59. As shown in the figure, it is advantageously arranged that the distal end 59 has claws arranged on the periphery of the distal end 59, which are radially embedded in the interface 92 to hold the needle 90 in the direction opposite to the distal direction X50. In a variant, instead of sleeve the needle 90 onto the rod distal end 59, it can be arranged to screw the needle 90 onto the rod distal end 59. The proximal attachment interface 92 then has an internal thread, and the rod distal end 59 has an external thread matching the internal thread so that tightening can be performed.

[0072] The cut-off distal end 91 extends from the interface 92 and the distal end 59 in the distal direction. The cut-off distal end 91 preferably has a convex shape or a plug form along the direction X50. Figures 1 to 3 In the distal position shown, the distal end 91 abuts against the shutoff seat 27 in the distal direction X50, thereby closing the shutoff seat 27. The duct 22 and the chamber 25 are thus fluidically separated, thereby preventing the establishment of the flow F21. Figure 4 In the proximal position shown, the distal end 91 is retracted relative to the shut-off seat 27 in a direction opposite to the direction X50, thereby releasing the seat 27. The duct 22 and the chamber 25 are then fluidically connected, so that a fluid flow F21 can be established.

[0073] A crown 93 is formed at the proximal end of the needle 90, i.e. axially opposite the shutoff distal end 91. The bottom of the internal conduit of the interface 92 is arranged between the crown 93 and the distal end 91. The crown 93 surrounds the entire circumference of the rod 52 at the groove 58 and covers the inner ring 82 from the outside, while the inner ring 82 is radially interposed between the crown 93 and the groove 58.

[0074] In more detail, the crown portion 93 includes a base 94 and a crown edge 95. Preferably, the crown portion 93 sequentially forms an inner inclined surface 96, an inner concave curved surface 97, and then an inner conical surface 98 on the inner side of the crown portion 93 in a direction opposite to the distal direction X50, as shown in FIG. Figure 3 These faces 96, 97 and 98 together form a continuous flared inner wall surrounding the rod 52.

[0075] The base 94 advantageously starts at the proximal end of the hub 92. In other words, the crown 93 extends from the internal canal formed by the hub 92 in a direction opposite to the direction X50. The crown 95 is arranged relative to the base 94 in a direction opposite to the distal direction X50, advantageously forming the proximal end of the needle 90 and the crown 93.

[0076] The base 94 connects the crown 93 to the shut-off distal end 91 and begins at the proximal end of the interface 92. The base 94 has an annular shape surrounding the rod 52. In the direction opposite to the direction X50, the base 94 begins adjacent to the piston groove distal edge 57 and extends radially outwards away from the rod 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, radially away from the rod 52. The crown rim 95 is preferably circular and extends completely around the rod 52 in a plane orthogonal to the axis X3. The crown rim 95 is arranged at the height of the piston groove proximal edge 56, that is, at the same level as the piston groove proximal edge 56 along the axis X3, or even beyond the piston groove proximal edge 56 in the direction opposite to the direction X50. Therefore, the crown 93 completely covers the groove 58, starting from the distal edge 57 of the crown 93 adjacent to the distal edge 57, and extending radially at a distance from the groove 58.

[0077] The inner bevel 96 converges in the distal direction X50 and is adjacent to the piston groove distal edge 57. The bevel 96 serves to prevent the formation of a sharp edge at the boundary between the needle 90 and the rod 52, thereby avoiding the risk of degradation of the collar 82 during use.

[0078] The circular hollow-shaped concave curved surface 97 connects the base 94 to the crown 95, more specifically, connects the inclined surface 96 to the inner conical surface 98. The surface 97 starts from the inclined surface 96 so that the piston groove distal edge 57 is offset in the direction X50 relative to the starting point of the surface 97. The concave curved surface 97 converges in the distal direction X50.

[0079] The inner conical surface 98 connects the base 94 to the crown 95, and more specifically connects the inner concave curved surface 97 to the crown 95. The surface 98 converges in the distal direction X50.

[0080] The inner ring 82 is housed in the groove 58, radially interposed between the crown 93 and the rod 52 relative to the axis X3, in contact with the crown 93, preferably in contact with the crown over the entire height or a large part of the height of the crown 93. More specifically, the ring 82 is in contact with faces 97 and 98. The crown 93 is inclined against the inner ring 82 by the concave curved surface 97 in the direction opposite to the distal direction X50. The inclined abutment enables the retaining ring 82 to be retained in the groove 58 by the needle 90, so that the retaining ring 82 is kept attached to the rod 52. The crown 93 is inclined against the diaphragm 80, more specifically against the ring 82, by the inner conical surface 98 in the direction opposite to the distal direction X50. The above arrangement helps to keep the retaining ring 82 in the groove 58.

[0081] The membrane 83 is attached to the retaining ring 82 by means of a distal portion 87 of the membrane 83 which is radially interposed relative to the axis X3 between the proximal edge 56 of the piston groove and the crown 95, in contact with the crown 95. More generally, the diaphragm 80 is radially interposed between the proximal edge 56 of the piston groove and the crown 95, in contact with the crown 95.

[0082] In other words, the septum 80 abuts against the crown 93 over the entire surface of the septum 80 radially interposed between the crown 93 and the stem 52, in particular at the crown 95, if appropriate, distal to the ring 82 at the edge 57. Preferably, the crown 95 remains in contact with the septum 80, whether the septum 80 is in one of the initial shapes, the stretched shapes or in any other shape during use. Preferably, the crown 95 remains in contact with the septum 80, whether the piston 50 is in the distal position, the proximal position or any intermediate position. Maintaining the support between the crown 95 and the septum 80 completely around the axis X3 prevents the opening of any annular gap between the septum 80 and the needle 90, thereby avoiding the insertion and accumulation of residues or other materials between the septum 80 and the crown 93. In order to maintain the contact between the crown 95 and the septum 80 in all such cases, it is provided that when the needle 90 is attached, the crown 93 is pushed onto the septum 80 so as to exert a force in a direction opposite to the direction X50, thereby pressing the septum 80 in a direction opposite to the direction X50 and maintaining it in an elastically deformed configuration. More specifically, it is provided that the ring 82 and the portion 87 of the membrane 83 are maintained in an elastically deformed state by obliquely pressing the faces 96 and 97 and the crown 95 against the ring 82 and the portion 87 of the membrane 83.

[0083] Preferably, the rod 52 comprises a proximal base 53 and an annular flange 55, which are located at the proximal end of the rod 52, opposite the portion 51 and the needle 90. Between the base 53 and the annular flange 55 on the one hand, and the portion 51 and the needle 90 on the other hand, the rod 52 extends through the intermediate chamber 37 and the control chamber 38 of the central duct 33. The annular 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 is opposite the needle 90. The proximal base 53 is arranged in the proximal chamber 39.

[0084] The valve 3 advantageously comprises a spring 54, which is supported on the valve body 30, here through the proximal base 53, exerting an elastic restoring force on the piston 50. The elastic restoring force tends to move the piston 50 from its proximal position to its distal position along the direction X50. Preferably, the spring 54 is arranged in the valve body 30, here around the piston 50 in the proximal chamber 39.

[0085] The control chamber 26 defined by the base 2 is fluidically connected to a control chamber 38 formed in the valve body 30. To this end, the valve body 30 forms one or more conduits (not shown) that connect the control chambers 26 and 38 when the valve body 30 is mounted on the base 2. Thus, a control fluid can enter the control chambers 26 and 38, and by pressurizing the chamber 38, a pressure is exerted on the annular flange 55, tending to move the piston 50 from the distal position to the proximal position against the force generated by the spring 54. By applying pressure by pressurizing the control fluid, the piston 50 is placed in the proximal position, and by releasing the pressure by reducing the control fluid pressure, the spring 54 will be allowed to return the piston 50 to the distal position. In this way, the opening and closing of the valve 3 can be controlled.

[0086] Like the peripheral chamber 28, the intermediate chamber 37 also forms a vent chamber. Preferably, the peripheral chamber 28 is fluidly connected to the intermediate chamber 37 by one or more conduits formed in the valve body 30, so that the chambers 28 and 37 together form a vent chamber. In the event of a failure of one of the seals or rings 81, the pressurized fluid or control fluid can escape through the failed seal towards the chambers 28 and 37 to prevent penetration into the rest of the valve 3.

[0087] The piston 50 and the diaphragm 80 can be considered as a piston-diaphragm assembly belonging to the valve 3 in a grouped manner. During the manufacturing process of the valve 3, the piston-diaphragm assembly is preferably installed in the valve body 30, and in the piston-diaphragm assembly, the ring 82 is already received in the groove 58 of the rod 52, and at the same time the needle 90 is already attached to the rod 52. The above operation involves inserting the piston 50 into the central tube 33 and then attaching the ring 81 into the groove 40. The valve body 30 is then installed in the bore 20 of the base 2. Similarly, for maintenance, the entire piston-diaphragm assembly can be replaced by removing the worn piston-diaphragm assembly from the valve body 30 as a unit and then reassembling the repaired piston-diaphragm assembly or a new piston-diaphragm assembly as a unit into the valve body 30.

[0088] To manufacture the piston-diaphragm assembly, a manufacturing method is used which comprises a number of steps described below.

[0089] Initially, the stem 52, needle 90, and septum 80 are provided in a configuration in which these components are separated from one another.

[0090] Then, if Figure 5 As shown, the method advantageously comprises positioning a temporary cap 100 on the stem distal end 59. At this stage, the needle 90 is not yet attached to the stem 52 and the inner ring 82 of the septum 80 is not yet assembled onto the stem 52.

[0091] The temporary cap 100 advantageously comprises a proximal base 102 by means of which the cap 100 is attached to the distal end 59 of the rod. Preferably, the proximal base 102 comprises a channel opening in a direction opposite to the direction X50 to accommodate the distal end 59 in the channel. Thus, the proximal base 102 covers the distal end 59, preferably completely, in particular any claws provided if appropriate at the distal end 59. Preferably, when the cap 100 is positioned, the base 102 extends to the distal edge 57 of the groove 58. Externally, the base 102 preferably has a cylindrical shape with a circular bottom centered on the axis X3.

[0092] The temporary cap 100 advantageously comprises, in the distal direction X50, a tapered distal end 101 centered on the axis X3 and whose end is advantageously rounded. Preferably, the distal end 101 forms an outer tapered surface 103, which is conical here. The surface 103 converges in the distal direction X50. The distal end 101 converges in the direction X50. The distal end 101 continues the external shape of the base 102, so that, from the outside, the cap 100 is completely tapered, for example having a cylindrical-conical overall shape.

[0093] Then, the method includes assembling the inner ring 82 onto the rod 52 when the needle 90 has not yet been attached to the rod and the cap 100 is located on the rod 52. The inner ring 82 is assembled through the distal end 59 until the inner ring 80 is accommodated in the piston groove 58 so as to attach the diaphragm 80 to the rod 52. Since the cap 100 has been installed, the inner ring 82 is assembled onto the rod 52 through the temporary cap 100, wherein the inner ring 82 slides along the outer conical surface 103 of the temporary cap in a direction opposite to the direction X50. The use of the cap 100 facilitates the assembly of the ring 82, because the tip of the temporary cap 100 can easily pass through the ring 82, and then the ring can be gradually elastically stretched as it gradually moves along the outer conical surface 103, and then once it passes through the cap 100, the ring finally elastically returns to a tighter shape so as to be accommodated in the groove 58. The cap 100 also advantageously makes it possible for the claws carried by the distal end 59 not to damage the ring 82.

[0094] The method then includes removing the temporary cap 100 when the inner collar 82 is received in the groove 58 and before attaching the needle 90 to the distal end 59 of the stem.

[0095] The method then consists in attaching the needle 90 to the rod distal end 59 when the inner ring 82 is housed in the groove 58 and the temporary cap 100 has been removed. To this end, the needle 90 is put on the rod 52 by pressing the proximal attachment interface 92 onto the rod distal end 59 in a direction opposite to the direction X50. If claws of the rod distal end 59 are provided, these claws prevent the withdrawal of the needle 90. The needle 90 is attached so that the crown 93 surrounds the rod 52, covers the inner ring 82 from the outside, makes the base 94 adjacent to the piston groove distal edge 57, and the diaphragm 80 is radially interposed between the piston groove proximal edge 56 and the crown rim 95, in contact with the crown rim 95, as described above.

[0096] As far as technically feasible, any feature described above for one of the embodiments or one of the variants can be used for the other embodiments and variants described above.

Claims

1. A piston-diaphragm assembly for a valve (3), the piston-diaphragm assembly comprising: - A piston (50) comprising: A rod (52) extending parallel to the distal direction (X50), the rod (52) being used to be received in the central conduit (33) of the valve body (30) in a manner of sliding relative to the valve body (30) of the valve (3) in parallel to the distal direction (X50), the rod (52) comprising a piston groove (58) surrounding the rod (52), the piston groove opening radially outward, the piston groove (58) comprising a piston groove proximal edge (56) and a piston groove distal edge (57), the piston groove (58) being defined between the piston groove proximal edge and the piston groove distal edge, the piston groove distal edge (57) being offset in the distal direction (X50) relative to the piston groove proximal edge (56), and a needle (90) fastened to a rod distal end (59) belonging to the rod (52), the needle being configured to abut against the shut-off seat (27) in a distal direction (X50) to close the pressurized fluid conduit (22); and - a diaphragm (80) comprising: a peripheral ring (81) for fastening the diaphragm (80) to the valve body (30) of the valve (3), the peripheral ring (81) surrounding the piston (50), an inner ring (82) surrounding the piston (50) and received in the piston groove (58) to thereby attach the diaphragm (80) to the piston (50), and an annular membrane (83) connecting the outer ring (81) to the inner ring (82); It is characterized in that the needle (90) includes a crown (93), which surrounds the rod (52) and covers the inner ring (82) from the outside, and the crown includes a crown edge (95), which terminates the crown (93) in a direction opposite to the distal direction (X50), and the crown edge (95) is arranged at the height of the proximal edge (56) of the piston groove, and the diaphragm (80) is radially interposed between the proximal edge (56) of the piston groove and the crown edge (95) and contacts the crown edge (95).

2. The piston-diaphragm assembly according to claim 1, wherein: The crown includes a base (94) adjacent the piston groove distal edge (57).

3. The piston-diaphragm assembly according to claim 2, wherein: The crown (93) includes an inner conical surface (98) connecting the base (94) to the crown edge (95), the inner conical surfaces converge in the distal direction (X50), and the crown (93) is inclined against the septum (80) in the direction opposite to the distal direction (X50) through the inner conical surface (98).

4. The piston-diaphragm assembly according to claim 2, wherein: The crown (93) includes a concave surface (97) connecting the base (94) to the crown edge (95), the concave surfaces converge in the distal direction (X50), and the crown (93) is inclined against the inner ring (82) in the direction opposite to the distal direction (X50) through the concave surface (97).

5. The piston-diaphragm assembly according to claim 2, wherein: The crown (93) comprises an inner bevel (96) which converges in the distal direction (X50) and is adjacent to the distal edge (57) of the piston groove.

6. The piston-diaphragm assembly according to any one of claims 1 to 5, wherein: The needle (90) comprises a proximal attachment interface (92) forming an internal channel, the needle (90) being fastened to the rod (52) by the proximal attachment interface, and the crown (93) extending from the proximal attachment interface (92) in a direction opposite to the distal direction (X50).

7. The piston-diaphragm assembly of claim 6, wherein: The needle (90) is secured to the rod (52) by fitting the rod distal end (59) into the proximal attachment interface (92) in the distal direction (X50).

8. The piston-diaphragm assembly according to any one of claims 1 to 5, wherein: The piston groove proximal edge (56) is radially wider than the piston groove distal edge (57).

9. The piston-diaphragm assembly according to any one of claims 1 to 5, wherein: The piston groove (58) has a radial section that is a portion of a circle from the piston groove distal edge (57) to the piston groove proximal edge (56).

10. A valve (3) comprising a piston-diaphragm assembly according to any one of claims 1 to 5, and wherein: - the valve (3) comprises a valve body (30) having a central duct (33) coaxial with the central axis (X3) and opening at a distal end (31) of the valve body belonging to the valve body (30); - the piston (50) can slide relative to the valve body (30) along the central axis (X3) between a distal position and a proximal position, and the distal direction (X50) of the piston (50) is parallel to the central axis (X3); - a rod (52) is received in the central conduit (33) and when the piston (50) is in the distal position, the rod extends out of the central conduit (33) from the distal end (31) of the valve body; - Whether the piston (50) is in the proximal position or the distal position, the needle (90) is arranged outside the central conduit (33) and is offset in the distal direction (X50) relative to the distal end (31) of the valve body; - a peripheral ring (81) attaching the diaphragm (80) to the valve body distal end (31); - a diaphragm (80) separating the central duct (33) from a pressurized fluid chamber (25) defined outside the diaphragm (80) in a distal direction (X50), the diaphragm being configured to deform elastically between the following shapes: an initial shape when the piston (50) is in the distal position and no overpressure occurs in the pressurized fluid chamber (25) relative to the central conduit (33), and a stretched shape under the effect of an overpressure occurring in the pressurized fluid chamber relative to the central conduit (33); The crown (95) contacts the diaphragm (80) whether the diaphragm (80) is in one of the initial shape or the stretched shape and whether the piston (50) is in the distal position or the proximal position.

11. A method for manufacturing a piston-diaphragm assembly according to any one of claims 1 to 5, the method comprising: - While the needle (90) is not yet fastened to the rod (52), the inner ring (82) is assembled onto the rod (52), the inner ring (82) being assembled through the rod distal end (59) until the inner ring (80) is received in the piston groove (58), so as to attach the diaphragm (80) to the rod (52); and - When the inner ring (82) is received in the piston groove (58), the needle (90) is fastened to the distal end (59) of the rod so that: The crown (93) surrounds the rod (52) and covers the inner ring (82) from the outside, and The diaphragm (80) is radially interposed between the piston groove proximal edge (56) and the crown rim (95) and contacts the crown rim (95).

12. The method according to claim 11, wherein: The method comprises: - positioning a temporary cap on the distal end (59) of the rod, the temporary cap covering the distal end (58) of the rod, while the needle (90) has not yet been fastened to the rod (52) and the inner ring (82) has not yet been assembled to the rod (52), and the inner ring (82) is assembled to the rod (52) through the temporary cap by sliding the inner ring (82) along the outer conical surface of the temporary cap, the outer conical surfaces converging in the distal direction (X50); and - With the inner collar (82) received in the piston groove (58), the temporary cap is removed before the needle (90) is secured to the rod distal end (59).

Images