Closing member for gas valves for very high pressures

Abstract

The invention relates to a valve closing member (12) for cooperation with a valve seat (14), comprising a body (16) with a front circular face (16.5) forming a central protrusion (16.2) along a longitudinal axis of the body, a seal (18) forming a ring fitted on the front circular face (16.5) and surrounding the central protrusion (16.2), and a retainer (20) forming a ring surrounding the seal (18) and attached to the body (16) for retaining the seal (18) on the body (16), wherein the seal (18) shows a radially inner surface (18.2) contacting a radially outer surface (16.4) of the central protrusion (16.2), both the radially inner surface (18.2) and the radially outer surface (16.4) being cylindrical, the radially outer surface (16.4) showing at least one circular groove (16.3) into which the seal is radially pressed by the retainer (20).

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of valves for compressed gases. BACKGROUND

[0002] The published prior art patent document US 8,297,593 B2 discloses a manual stop valve for compressed gases. The valve comprises a closing member movable with respect to a valve seat formed in a valve body. The closing member comprises a body having a front circular face forming a central protrusion along a longitudinal axis of said body, a seal formed as a ring fitted on the front circular face and surrounding the central protrusion, and a retainer formed as a ring surrounding the seal and attached to the body for retaining said seal on said body. The central protrusion shows a radially outer surface tapering from the front circular face and having a bead at a distal end for fixing the seal. This means that the seal needs to be deformed elastically by extension during mounting on the central protrusion. The joint between the seal and the body, in particular between the radially inner surface of the seal and the corresponding radially outer surface of the central protrusion, is designed to withstand pressures up to 300 bar.

[0003] The published prior art patent document WO 2015 / 044044 A1 discloses a stop valve for compressed gases comprising a closing member cooperating with a valve seat, the closing member being located upstream of the valve seat and comprising an elongated member extending downward through the valve seat. The stop valve is self-closing, since a spring located upstream of the valve seat pushes the closing member against said valve seat for closing the gas passage. Once the gas passage is closed, the pressure upstream, i.e. at the inlet, urges the closing member against the valve seat. The closing member comprises a body having a front face and a central elongated member, around which a seal is mounted and vulcanized. A sleeve slides longitudinally along an outer surface of the seal so as to house said seal. This structure of the closing member is useful for self-closing valves using softer sealing material. It is not suitable for stop valves, in which the closing member is located downstream of the valve seat and is operated by a mechanism exerting a force pushing the closing member against the inlet pressure. SUMMARY

[0004] Technical problem

[0005] The technical problem addressed by the present invention is to overcome at least one of the drawbacks of the above-mentioned prior art. More specifically, the technical problem addressed by the present invention is to provide a stop valve for compressed gases, which is highly reliable and suitable for very high inlet pressures, e.g. above 300 bar.

[0006] Technical solution

[0007] The invention relates to a valve closing member for cooperation with a valve seat, comprising a body, a front circular face of the body forming a central protrusion along a longitudinal axis of the body, a seal forming a ring fitted on the front circular face and surrounding the central protrusion, and a retainer forming a ring surrounding the seal and attached to the body for retaining the seal on the body, wherein the seal shows a radially inner face contacting a radially outer face of the central protrusion, both the radially inner face and the radially outer face being cylindrical, the radially outer face showing at least one circular groove into which the seal is radially pressed by the retainer.

[0008] Advantageously, the at least one circular groove is located on a longitudinally intermediate portion of the radially outer face, which means that the at least one circular groove is longitudinally distanced from both longitudinally opposite ends of the radially outer face.

[0009] According to a preferred embodiment, both the radially inner face and the radially outer face are cylindrical and longitudinally extend over the entire effective length of the central protrusion.

[0010] According to a preferred embodiment, both the radially inner face and the radially outer face are cylindrical and longitudinally extend from the front face to the distal end of the central protrusion.

[0011] According to a preferred embodiment, each of the at least one circular groove shows a width less than 50%, preferably less than 40%, more preferably less than 30% of the total length of the central protrusion along its radially outer face in the longitudinal direction.

[0012] According to a preferred embodiment, the at least one circular groove comprises at least two of said circular grooves.

[0013] According to a preferred embodiment, the at least one circular groove is formed on a proximal half of the radially outer face of the central protrusion, said proximal half being adjacent to the front circular face.

[0014] According to a preferred embodiment, the at least one circular groove shows a penetration direction inclined with respect to a plane perpendicular to the longitudinal axis, the inclination angle being distanced from the front circular face.

[0015] According to a preferred embodiment, the penetration direction of the at least one circular groove shows an inclination angle comprised between 30° and 60°.

[0016] According to a preferred embodiment, the retainer has a radially inner face showing a cross-sectional profile L-shaped with a shorter distal radially extending branch and a longer longitudinally extending branch.

[0017] According to a preferred embodiment, the longer longitudinally extending branch of the L-shaped cross-sectional profile of the radially inner face of the retainer comprises a proximal portion tapering radially outwards.

[0018] According to a preferred embodiment, the shorter radially extending branch of the L-shaped cross-sectional profile of the radially inner surface of the retainer is curved and concave, such that the distal end of said branch forms a longitudinal facing split of the seal.

[0019] According to a preferred embodiment, the radially outer surface of the seal has a cross-section which is shown to be L-shaped and in contact with the L-shaped cross-section of the radially inner surface of the retainer, said.

[0020] According to a preferred embodiment, the L-shaped profile of the cross-section of the radially outer surface of the seal comprises a shorter distal radially extending branch and a longer longitudinally extending branch, wherein at least one branch, preferably both branches, are straight before the retainer is mounted to encircle the seal.

[0021] According to a preferred embodiment, the retainer is attached to the body by a weld of said retainer and said body periphery.

[0022] The present invention also relates to a valve for compressed gas, comprising: a valve body with a gas inlet, a gas outlet and a gas passage fluidly interconnecting said gas inlet and gas outlet; a valve seat located in the valve body and traversed by the gas passage; a closing member configured to cooperate with said valve seat for selectively opening and closing said gas passage; an actuation mechanism for moving the closing member between an open position and a closed position of the gas passage; wherein the valve closing member is according to the invention.

[0023] Advantages of the present application

[0024] The present invention is of particular interest in that it provides a more reliable valve closing member, especially suitable for very high pressures, for example above 300 bar. The sealing material penetrating at least one annular groove formed on the radially outer surface of the central protrusion forms a gas-tight barrier preventing a large amount of compressed gas from penetrating between the circular front surface of the closing member body and the rear surface of the seal opposite thereto, which would then displace the seal out of position and cause failure of the valve. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a cross-sectional view of a gas valve according to the invention.

[0026] Figure 2 is Figure 1 is an enlarged view of the closing member and valve seat of the gas valve in

[0027] Figure 3 is Figure 1 and Figure 2 is an exploded cross-sectional view of the closing member of the gas valve in DETAILED DESCRIPTION

[0028] Figure 1 Figure 1 is a longitudinal sectional view of a gas valve according to the invention.

[0029] For example, Figure 1 The gas valve 2 in Figure 1 is a shut-off valve, i.e. a valve designed for selectively closing or opening a gas passage, as opposed to a regulating valve designed for controlling the gas pressure and / or flow through said valve. However, the invention is applicable to regulating valves as well.

[0030] The gas valve 2 comprises a valve body 4, which is only partly represented, but shows all functional features of said valve. The valve body 4 comprises a gas inlet 6, a gas outlet 8 and a gas passage 10 fluidly interconnecting said gas inlet and outlet. The gas valve 2 further comprises a movable closing member 12 and a corresponding valve seat 14. The valve seat 14 is for example directly formed in the valve body 4, but can also be formed by a separate part mounted and attached to the valve body 4. The valve seat 14 is annular and surrounds the gas passage 10. For example, the valve seat 14 forms an annular boss on the bottom face of a bore formed in the valve body 4, through which boss a through hole of the gas passage 10 is formed at the inlet 6. The closing member 12 comprises a body 16, preferably made of metal, having a central protrusion on a front circular face, a seal 18, which is annular and fits on the front face around the central protrusion, and a retainer 20, which forms a ring around the seal and is attached to the valve body 4. Reference will be made to Figure 2 and Figure 3 The closing member 12 is described in detail.

[0031] Still in Figure 1 The gas valve 2 further comprises an actuating mechanism 22 for moving the closing member 12 between an open position and a closed position of the gas passage 10. The actuating mechanism 22 comprises a spindle 24 inserted in and supported by a bushing 26 rigidly mounted on the valve body 4, and a closing member carrier 28 anchored to a proximal end of the spindle 24. A hand wheel 25 is attached to a distal end of the spindle 24 for rotating said spindle, thereby selectively opening or closing the valve depending on the direction of rotation. For example, the spindle 24 comprises an external thread engaging a corresponding internal thread in the bushing 26, which means that rotation of the spindle 24 induces a translational movement along the longitudinal axis of said spindle. The proximal end of the spindle 24 forms a generally U-shaped cavity 24.1, two retaining arms longitudinally engaging a circular protruding portion 28.1 of the closing member carrier 28. A press ball 24.2 is housed in the bottom of the U-shaped cavity 24.1 for contacting an outer surface of the circular protruding portion. This outer surface is advantageously curved and convex, so that the contact with the press ball 24.2 is close to a point contact, thereby greatly reducing the friction in rotation.

[0032] The closing member carrier 28 shows for example a first outer cylindrical surface 28.2 and a second outer cylindrical surface 28.3 of smaller diameter than the first outer cylindrical surface 28.2. The first outer cylindrical surface 28.2 is slidingly engaged in a corresponding hole formed in the bushing 26, while the second outer cylindrical surface 28.3 is slidingly engaged in a corresponding hole formed in the pressure ring 30, which is interposed between the front cylindrical face of the bushing 26 and a stack of flexible membranes 32 resting on a shoulder formed in the valve body 4.

[0033] The body 16 of the closing member 12 comprises a rear stud 16.1 which is engaged in a corresponding threaded blind hole 28.4 formed in the closing member carrier 28. As this is apparent in Figure 1 The stack of flexible membranes 32 is fitted around the stud 16.1 of the body 16 of the closing member 12 and is clamped between the outer surface of the closing member body 16 directly around the stud 16.1 and the front circular face of the closing member carrier 28. In other words, the stack of flexible membranes is fixed to the closing member 12 and to the closing member carrier 28 during its assembly.

[0034] Back to the bushing 26, the latter is firmly fastened by threaded engagement on said body, clamping the periphery of the stack of flexible membranes 32 between the shoulder of the valve body 4 and the pressure ring 30, the flexible membranes 32 resting on the shoulder of the valve body 4, the pressure ring 30 being interposed between said stack of flexible membranes 32 and the front cylindrical surface of the bushing 26. The latter can show a non-circular outer surface, for example a hexagonal surface, to allow rotational engagement with a tightening tool.

[0035] The stack of flexible membranes 32, advantageously made of metal, such as spring steel, provides a gas-tight barrier for the chamber in which the closing member 12 is located in the gas passage.

[0036] Figure 2 is Figure 1 is a magnified view of the closing member 12 and of its valve seat 14. The central protrusion 16.2 of the closing member body 16 comprises on its radially outer surface two circular grooves 16.3 in which the material of the seal 18 is pressed. In Figure 2 In the figure, the seal is shown in its original shape, i.e. not deformed by the retainer, while in practice the sealing material is radially pressed into the circular grooves 16.3 by the retainer 20. To this end, the retainer 20 shows a profiled radially inner surface 20.1 which is wedge-shaped, so that when placed longitudinally around the seal 18, the wedge-shaped radially inner surface will radially press the sealing material into the circular grooves 16.3. As this is apparent, the retainer 20 is attached to the closing member body 16 by a weld 34 extending around its periphery.

[0037] The above structure allows the valve to function properly at high pressures up to 600 bar. At more common industrial gas pressures, for example around 200 bar, the inventors of the present application have found that it is not problematic in principle if pressurized gas penetrates between the radially outer surface 16.4 of the central protrusion 16.2 and the radially inner surface of the seal 18, and possibly further between the circular front surface of the shut-off member body 16 and the corresponding surface of the seal 18, mainly because in use (for example when the high pressure in the gas cylinder is gradually reduced) a small amount of gas under pressure will escape from between the shut-off member body 16 and the seal 18 without moving the seal 18 relative to the shut-off member body 16. The L-shaped cross-section of the retainer is sufficient to prevent the seal 18 from moving relative to the shut-off member body. At higher pressures, however, things are different. The presence of the at least one circular groove 16.3, in combination with the radial extrusion of the material of the seal 18 into the retainer 20 of the at least one circular groove 16.3, prevents the penetration of gas under pressure between the shut-off member body 16 and the seal 18. This thus prevents the seal 18 from possibly being displaced when the shut-off member is operated at higher pressures, for example up to 600 bar.

[0038] Figure 3 For Figure 1 and Figure 2 a cross-sectional view of the shut-off member 12. More specifically, Figure 3 the shut-off member body 16, the seal 18 and the retainer 20 are shown.

[0039] As will be apparent, the circular front surface 16.5 of the shut-off member body 16 can present a stepped profile, i.e. an inner annular portion 16.5.1 which contacts the seal 18 and an outer annular portion 16.5.2 which forms a recess relative to the inner annular portion 16.5.1, the outer annular portion contacting the retainer 20 and receiving the weld 34 Figure 1 The inner and outer annular portions 16.5.1 and 16.5.2 are preferably planar.

[0040] The central protrusion 16.2 of the shut-off member body 16 shows a radially outer surface 16.4 which is cylindrical, from the circular front surface 16.5 (for example the inner portion 16.5.1 thereof) to the bevel at the distal end of the central protrusion 16.2. Two circular grooves 16.3 are advantageously located on a longitudinal half of the radially outer cylindrical surface 16.4 of the central protrusion 16.2 of the shut-off member body 16, said half being adjacent to the circular front surface 16.5 of said shut-off member body 16. At least one of the two circular grooves 16.3, preferably each, is located on a longitudinal middle portion of the radially outer surface 16.4, which means that the circular groove 16.3 is longitudinally distanced from each of the two longitudinally opposite ends of the radially outer surface 16.4.

[0041] As will be apparent, the circular recess 16.3 is shown as a curved U-shaped cross section. It shows a penetration direction with an inclination a relative to a plane perpendicular to the longitudinal axis, which is oriented away from the front circular face. The inclination a can be comprised between 30° and 60°. This orientation is advantageous for manufacturing and performance reasons. Indeed, when turning the circular recess on a lathe, it is significantly easier to orient the cutting tool accordingly, thereby avoiding any risk of interference with the circular front face 16.5. Moreover, during the assembly of the closing member 12, and in particular during the assembly of the retainer 20 on the seal 18, which is pre-assembled around the central protrusion 16.2 and against the circular front face 16.5 of the closing member body 16, a combination of radial (due to compression) and longitudinal (due to friction) forces is exerted on the seal. The resultant force is then oriented with an inclination a close to or equal to the inclination of the main direction of the cross-sectional profile of the circular recess 16.3. This is therefore advantageous for the correct insertion of the sealing material into the annular recess 16.3.

[0042] The seal 18 shows a radial outer surface 18.1 with a generally L-shaped cross-sectional profile, i.e. with a longer longitudinal branch 18.1.1 and a shorter radial branch 18.1.2. The two branches 18.1.1 and 18.1.2 are preferably straight before being contacted by the retainer 20. The radial outer surface 18.1 of the seal 18 also comprises a further portion 18.1.3 which is longitudinal and adjacent to the shorter radial branch 18.1.2 of the L-shaped cross-sectional profile.

[0043] As mentioned above, the radial inner surface 18.2 of the seal 18 is cylindrical, i.e. straight and longitudinal before being contacted by the closing member body 16.

[0044] The seal 18 also comprises a rear surface 18.3 which is in contact with the inner annular portion 16.5.1 of the circular front surface 16.5 of the closing member body 16. A front surface 18.4 of the seal is intended to contact the valve seat 14 (see Figure 1 and 2 ).

[0045] The retainer 20 shows a shaped wedge-shaped radial inner surface 20.1. This radial inner surface 20.1 is designed to contact the above-mentioned radial outer surface 18.1 of the seal 18 and more particularly to press the sealing material 18 into the annular recess 16.3. Its cross-sectional profile is similar to the L-shaped one of the radial outer surface 18.1 of the seal 18, i.e. with a longer longitudinal branch 20.1.1 + 20.1.2 + 20.1.3 and a shorter radial branch 20.1.4. Contrary to the branches of the L-shaped profile of the radial outer surface 18.1 of the seal 18, the longer longitudinal and shorter radial branches 20.1.1 + 20.1.2 + 20.1.3 and 20.1.4 are not straight.

[0046] The longer longitudinal branch 20.1.1 + 20.1.2 + 20.1.3 comprises a first longitudinal portion 20.1.1 which is straight and which is shown with a diameter identical to the diameter of the longer longitudinal branch 18.1.1 of the L-shaped radial outer surface 18.1 of the seal. The longer longitudinal branch 20.1.1 + 20.1.2 + 20.1.3 further comprises a second longitudinal portion 20.1.3 which can also be straight and which is shown with a diameter smaller than the diameter of the first longitudinal portion 20.1.1, and an intermediate sloped portion 20.1.2 interconnecting the first and second longitudinal portions 20.1.1 and 20.1.3. The intermediate sloped portion is for example straight but can be shown with a curved profile. This portion forms a ramp for radially compressing the sealing material during the installation of the retainer 20 on the seal 18. It can be considered that the second longitudinal portion 20.1.3 and the intermediate sloped portion 20.1.2 radially project inwardly for compression purposes of the sealing material. In Figure 3 The volume of the radially inwardly projecting portion shown by 20.3 in (right section of the retainer 20) is approximately identical to the volume of the circular recess 16.3. Preferably, it is comprised between 50% and 100% of the volume of the circular recess 16.3.

[0047] The shorter radial branch of the L-shaped cross-sectional profile of the radial inner surface of the retainer 20, 20.1.4, presents a curved concave profile so that the distal end of said branch forms a cleft oriented longitudinally towards the seal 18.

[0048] The radial inner surface 20.1 of the retainer 20 comprises another portion 20.1.5 proximate to the distal end of the shorter radial branch of the L-shaped cross-sectional profile of said radial inner surface 20.1. This other portion 20.1.5 is longitudinal and has a reduced diameter compared to the longer longitudinal branch of the L-shaped cross-sectional profile of the radial inner surface 20.1; this reduced diameter corresponds to the diameter of the other portion 18.1.3 of the radial outer surface 18.1 of the seal 18.

[0049] The longer longitudinal branch 20.1.1 + 20.1.2 + 20.1.3 can comprise a radially outwardly tapered portion 20.1.6 for facilitating the engagement of the radial inner surface 20.1 of the retainer 20 along the radial outer surface 18.1 of the seal 18.

[0050] The retainer 20 comprises a rear surface 20.2 which is in contact with the outer annular portion 16.5.2 of the circular outer surface 16.5 of the closure member body 16, before being welded to form a weld 34 Figure 2 ).

[0051] The closing member body 16 and the retainer 20 are advantageously made of metal, while the seal 18 is advantageously made of a softer, non-metallic material, such as a plastic material.

[0052] The above-described structure is particularly advantageous because it provides a highly reliable gas valve, particularly at very high pressures, i.e. of the order of 300 bar.

Claims

1. A valve closing member (12) for cooperating with a valve seat (14), comprising: - A main body (16) having a front circular surface (16.5) forming a central protrusion (16.2) along the longitudinal axis of the main body; - A seal (18) that forms a ring fitted on the front circular face (16.5) and surrounding the central protrusion (16.2); and - A retainer (20) that forms a ring around the seal (18) and is attached to the body (16) for retaining the seal (18) on the body (16); Its features are, The seal (18) shows a radially inner surface (18.2) of the radially outer surface (16.4) of the contact center protrusion (16.2), both the radially inner surface (18.2) and the radially outer surface (16.4) of the seal (18) are cylindrical, and the radially outer surface (16.4) of the center protrusion (16.2) shows at least one circular groove (16.3) in its longitudinal middle portion, into which the seal is radially pressed by the retainer (20); and The retainer (20) shows a shaped radial inner surface (20.1), which is L-shaped with a shorter radial branch (20.1.4) and a longer longitudinal branch (20.1.4). 20.1.1, 20.1.2, 20.1.3), the longer longitudinal branch includes an intermediate inclined portion (20.1.2) that forms a ramp for radially compressing the seal (18) during the process of mounting the retainer (20) onto the seal (18).

2. The valve closing member (12) according to claim 1, wherein, The radial inner surface (18.2) of the seal (18) is cylindrical and the radial outer surface (16.4) of the central protrusion (16.2) extends longitudinally over the entire effective length of the central protrusion (16.2).

3. The valve closing member (12) according to any one of claims 1 and 2, wherein, The radial inner surface (18.2) of the seal (18) is cylindrical and the radial outer surface (16.4) of the central protrusion (16.2) extends longitudinally from the front circular surface (16.5) to the far end of the central protrusion (16.2).

4. The valve closing member (12) according to claim 1, wherein, The width of each of the at least one circular groove (16.3) shown is less than 50% of the total length of the central protrusion (16.2) along the radial outer surface (16.4) of the central protrusion (16.2) in the longitudinal direction.

5. The valve closing member (12) according to claim 1, wherein, The at least one circular groove (16.3) includes at least two circular grooves (16.3).

6. The valve closing member (12) according to claim 1, wherein, The at least one circular groove (16.3) is formed on the near half of the radially outer surface (16.4) of the central protrusion (16.2), the near half being adjacent to the front circular surface (16.5).

7. The valve closing member (12) according to claim 1, wherein, The at least one circular groove (16.3) shows a penetration direction that is inclined relative to a plane perpendicular to the longitudinal axis, the inclined penetration direction being oriented away from the front circular surface (16.5).

8. The valve closing member (12) according to claim 7, wherein, The angle of inclination of the penetration direction of at least one circular groove (16.3) is an angle α contained between 30° and 60°.

9. The valve closing member (12) according to claim 1, wherein, The L-shaped, longer longitudinally extending branch of the radial inner surface (20.1) of the retainer (20) 20.1.1, 20.1.2, 20.1.3) include a proximal portion that widens radially outward (20.1.6).

10. The valve closing member (12) according to claim 1, wherein, The shorter, L-shaped radial extension branch (20.1.4) of the radial inner surface (20.1) of the retainer (20) is curved and concave, such that the distal end of the branch forms a slit oriented longitudinally toward the seal (18).

11. The valve closing member (12) according to claim 1, wherein, The seal (18) has a radially outer surface (18.1) that has an L-shaped cross-sectional profile and contacts the L-shaped radially inner surface (20.1) of the retainer (20).

12. The valve closing member (12) according to claim 11, wherein, The L-shaped profile of the cross section of the radial outer surface (18.1) of the seal (18) includes a shorter distal radial extension branch (18.1.2) and a longer longitudinal extension branch (18.1.1), wherein at least one of the branches is straight before the retainer (20) is installed around the seal (18).

13. The valve closing member (12) according to claim 1, wherein, The retainer (20) is attached to the body (16) by a weld (34) located on the outer periphery of the retainer and the body.

14. A valve (2) for compressing gas, characterized in that, include: - Valve body (4), which has a gas inlet (6), a gas outlet (8) and a gas passage (10) that fluidly interconnects the gas inlet and the gas outlet; - Valve seat (14), which is in the valve body (4) and is passed through by the gas passage (10); - The valve closing member (12) according to any one of claims 1 to 13 is configured to cooperate with the valve seat (14) for selectively opening and closing the gas passage (10); -Actuation mechanism (22) for moving the valve closing member (12) between the open and closed positions of the gas passage (10).

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