FR2878985A1 - Balanced pressure reducer for respiration equipment has valve made from two different materials - a hollow metal body and a covering layer of a rigid synthetic material - Google Patents

Abstract

The pressure reducer, especially for gases at high or very high pressure, consists of a housing (7) with a high-pressure inlet (10) and a low-pressure outlet (11), and a valve (1) that can move between opoen and closed positions and interact with a seat (6). The valve is made from two different materials - a hollow central body of a hard material resistant to high pressure, such as a metal, covered at least partly by a moulded layer of a rigid synthetic material that is hard and resistant to abrasion and makes contact with the valve seat, which is made from two synthetic materials having different degrees of rigidity.

Description

The present invention relates to a balanced pressure reducer, and

  in particular a balanced pressure reducer at high pressures.

  A balanced pressure reducer, particularly for high or very high pressure breathing equipment (200 to 400 bar) generally comprises a movable valve member which moves axially within a high pressure chamber formed in the body of the valve. device. The movable valve member is also metallic and has an enlarged head connected to a rod. A through axial bore extends from the head through the stem and acts as a pressure equalizing means. The movable valve member is disposed between a high pressure inlet, a valve seat which separates the high pressure chamber from a low pressure chamber, and a seal, such as an O-ring, which delimits a pressure balancing chamber. The valve seat acts against a relatively soft portion of the valve member head and the O-ring acts against the stem of said valve member. In order to obtain pressure equalization, the diameters of the contact surfaces and thus the closure of the high-pressure valve seat and the stem of the valve element are usually of the same size. In this type of pressure reducer arises particularly a problem in the sealing between the valve member and the valve seat.

  Various solutions have been proposed for producing such pressure reducers. One solution is to use a metal such as stainless steel for the valve member and to polish the metal surface of the valve member which cooperates with the valve seat in the closed position. This avoids the risks associated with the use of less expensive metal, such as brass, namely oxidation in the absence of protective plating or delamination in case of plating, for example nickel. However, this implementation is very expensive. US-5,746,198 discloses a movable valve member which is made of metal and which has, at the upper surface of the enlarged head, a relatively soft plastic molded material which is mechanically retained and chemically bonded to the metal head said valve member. This relatively flexible material is intended to rest against the seat of high pressure valve, also metallic. This implementation has certain disadvantages. Indeed, the junction between the flexible plastic material, which covers only the enlarged head, and the metal body of the valve member is exposed to the action of high pressure. This can lead to delamination or delamination of the plastic layer, which can be extremely dangerous since the high pressure may then pass directly into the low pressure chamber. In order to solve this problem, it is intended to apply a binder to the metal head of the valve member. This procedure, besides the fact that it is very expensive and difficult to reproduce in a constant manner, does not completely eliminate the risk of delamination or detachment of the flexible plastic layer, since the metal body and the plastic layer remain two materials. chemically incompatible. In addition, in case of wear of the plastic layer, no sealing is no longer provided by the system, since the high pressure valve seat comes into direct contact with the metal head of the valve member. Another solution is disclosed in US-5,139,046 and US-5,413,096, which discloses a movable valve member also having a metal body, a flexible plastic material being molded over the entire enlarged head of said valve element but also over most of the rod, leaving only the axial bore and a shoulder adjacent to the free end of the rod free of plastic material. In this implementation, the entire portion of the valve element which is exposed to the high pressure (head and rod) is continuously covered by a flexible material molded onto the metal body of the valve element, and by therefore any risk of delamination or delamination is avoided. On the other hand, the fact that the plastic coating is flexible, associated with the fact that this plastic covering also covers the major part of the rod, can present a disadvantage. Indeed, the seal of the balancing chamber, generally made in the form of an O-ring, which cooperates with the rod, then risks compressing the flexible plastic layer and form a kind of groove. The result could then be a reduction in the diameter of the stem with negative consequences on pressure equalization and increased friction of the displacement of the valve element, with a delay resulting in the opening of the valve at the seat valve. Moreover, the valve elements described above all have a complex metal structure, with a stem and an enlarged head, which makes their manufacture complex. Similarly, the molding of the flexible material around this complex form is complicated and expensive.

  The present invention aims to provide a balanced pressure reducer that does not reproduce the aforementioned drawbacks.

  Thus, the present invention aims to provide a balanced pressure reducer I o which achieves a good seal, and which also eliminates any risk of loss of balance, especially at the level of the ring seal of the balancing chamber .

  The present invention also aims to provide such a balanced pressure reducer that is simple and inexpensive to manufacture and assemble and reliable in use.

  The present invention therefore relates to a balanced pressure reducer, especially for high or very high pressure gases, comprising a body defining a high pressure inlet and a low pressure outlet, a valve element being disposed between said high pressure inlet and said low pressure outlet, said valve element being movable between an open position, in which it opens a passage between said high pressure inlet and said low pressure outlet, and a closed position, in which it cooperates with a valve seat for closing said passage, said valve element consisting of two different materials, and comprises a hollow central body made of hard material and resistant to very high pressures, such as metal, said central body being at least partially covered with a layer of Rigid synthetic material, hard and abrasion resistant.

  Advantageously, the portion of the valve member in contact with said valve seat is formed on said layer.

  Advantageously, said layer is molded on said central body.

  Advantageously, said central body has a substantially cylindrical shape.

  Advantageously, said valve element has, in cross section, a T-shaped shape comprising a hollow rod and an enlarged head, said head being provided with at least one projection comprising the zone of the valve element cooperating with said seat of valve.

  Advantageously, said enlarged head is formed by said layer.

  Advantageously, said valve element comprises at least one projection cooperating with said valve seat in the closed position.

  According to an advantageous embodiment, the valve seat forms a substantially tubular hollow structure having an internal passage and defining an end surface, said valve member cooperating in the closed position with any point of said end surface. .

  Advantageously, said valve element comprises at least one projection comprising a non-cutting contact tip cooperating with any point of said end surface of the valve seat.

  Advantageously, said valve seat comprises a sleeve made of a rigid synthetic material.

  Advantageously, said valve seat is made from at least two materials of different stiffnesses, the material of lesser rigidity forming the contact zone of said valve seat with said valve element in the closed position.

  Advantageously, an end surface of said sleeve is coated with a less rigid synthetic material cooperating with said valve member in the closed position.

  Advantageously, said end surface is overmolded on said sleeve, in particular by injection molding.

  Advantageously, the synthetic materials forming said sleeve and said end surface are chemically compatible and of different hardness and / or modulus of elasticity (s).

  Advantageously, the synthetic materials forming said sleeve and said end surface are of the same type, such as a thermoplastic elastomer.

  Advantageously, said sleeve and said end surface are formed from the same synthetic material, such as a thermoplastic elastomer, especially polyurethane, said sleeve being reinforced by reinforcing means, such as glass fibers.

  Advantageously, after molding, said sleeve and said end surface are intimately connected to each other, said connection being resistant to high pressures.

  Advantageously, said valve member is moved to its open position by a control member which, when the pressure of the gas is less than a predetermined pressure threshold, is biased by a first elastic element, such as a spring, to an actuating position corresponding to the opening position of the valve element, said first elastic element, from said predetermined pressure threshold, no longer biasing said control member towards its actuating position so that said element valve is then urged elastically towards its closed position by a second elastic element, such as a spring.

  Advantageously, said control member is separated from said first elastic element by a membrane.

  Other characteristics and advantages of the present invention will appear more clearly in the following detailed description of several particular embodiments thereof, with reference to the accompanying drawings, given by way of non-limiting examples, and on which Fig. 1 is a schematic cross-sectional view of a balanced pressure reducer according to an advantageous embodiment of the present invention, in the closed position of the valve member; and Figure 2 is a schematic cross-sectional view of the valve member shown in Figure 1, cooperating with a modified valve seat.

  Referring to Figure 1, the pressure reducer comprises a main body 7 which defines a high pressure chamber 8, a low pressure chamber 9, a high pressure inlet 10 and a low pressure outlet 11. The low pressure chamber 9 is separated from the high pressure chamber 8 by a valve having a valve seat 6 cooperating with a movable valve element 1. The valve seat 6 preferably has the shape of a substantially tubular sleeve 61 which co-operates with an upper projection of a enlarged head of the movable valve member 1, to ensure a perfect seal in the closed position of said valve.

  The movable valve member 1 preferably has a cross-sectional T-shape, with a rod portion connected to an enlarged head portion.

  This valve element 1 is preferably hollow and therefore comprises an axial through bore 16. Advantageously, a shoulder 15 is provided inside said through bore 16. The low pressure chamber 9 is further closed by a membrane 12, which separates a first elastic element 13, such as a load spring, of a control element 14 movably disposed in said low pressure chamber 9. The control element 14 thus rests on one side against the membrane 12 and the other side, through axial extension, against the shoulder 15 provided inside the through bore 16 formed in the movable valve member 1, to feed a balancing chamber 17 with low pressure. This balancing chamber 17 is in turn hermetically sealed by means of a seal 4, in particular an O-ring, as well as by a suitable ring, such as an anti-extrusion ring 18, acting both on the stem of movable valve element 1.

  The movable valve member 1 may be inserted into a guide member 19 provided with appropriate side openings 19 ', to allow gas flow, said guide member and / or said enlarged head resting against a second elastic member 20 , such as a spring, which urges said movable valve member 1 towards its closed position. It should be noted that the guide element 19 is not essential, the lateral openings 19 'can be made directly on the valve member 1, in particular on the enlarged head. However, it is advantageous to use such a metal guide element to cooperate with the spring 20, advantageously also metallic, in order to avoid risks of wear of the enlarged head at the contact surface with said spring 20. Preferably, the diameter of the stem of the movable valve member 1 and the diameter of the contact or closure surface of the valve seat 6 against the valve member 1 are identical, to ensure optimum balancing of the reducer o pressure.

  When the low pressure outlet 11 is closed, the pressure in the low pressure chamber 9 acting against the diaphragm 12 overcomes the load of the load spring 13, so that the control element 14 is not compressed towards the movable valve member 1. The movable valve member 1, urged by its own spring 20, then closes the valve by being pressed against the valve seat 6.

  In this condition, the system is fully balanced: the high pressure acts on the entire surface of the movable valve element 1 except for its part which is located inside the closing diameter of the valve seat 6 and except for the corresponding part of the stem section, these two excluded parts having the same dimension. On the other hand, the low pressure acts on the surface of the valve member 1 delimited by the valve seat 6 and on the surface corresponding to the cross section of the rod, which are also of the same size.

  In this situation, even a small air outlet through the low pressure outlet and consequent reduction of the pressure in the chamber 9 causes the membrane to move downwardly under the action of the load spring 13, so that the valve is immediately opened by means of the control element 14, which displaces the movable valve element 1 with respect to the valve seat 6. When the valve is open, gas can flow from the high pressure chamber 8 to the low pressure chamber 9 (and thus to the low pressure outlet 11) until the pressure in the low pressure chamber 9 reaches again the threshold where the load of the load spring 13 is overcome. At this time, the membrane 12 compresses said load spring 13, so that the return spring 20 of the valve member 1 can bring it back to its closed position, shown in FIG. 1.

  According to the invention, the movable valve element 1 consists of two different materials, and comprises a central body 2 made of a hard material and resistant to high or very high pressures, which can typically be of the order of 200 to 400 bars in this type of pressure reducer. Preferably, this rigid central body 2 is made of metal. A layer 3 made of hard and abrasion-resistant rigid synthetic material is molded on at least a portion of said central body 2, being continuous at least on the portion subjected to high pressures. This layer 3 must be sufficiently hard, rigid and resistant to wear and abrasion to always ensure a good closure against the valve seat 6. As shown in Figure 2, the layer 3 advantageously forms the enlarged head of the movable valve member 1, so that the central body 2 may be simple in shape, for example substantially cylindrical. This simplifies its manufacture, especially when it is metal. Advantageously, the contact zone of the valve element 1 with the valve seat 6 is formed on said layer 3. Advantageously, this layer 3 is made of a resistant material, such as for example LCP (Liquid Crystal Polymer), polysulfone or polyarylamide. The invention thus makes it possible to use an inexpensive metal to produce the central body. Furthermore, the invention makes it possible to simply and inexpensively produce any shape suitable for the layer 3, in particular for producing the profile or projection of contact with the valve seat 6 in the closed position. It is also easier to obtain a high surface polish as compared to metal.

  According to an advantageous embodiment, shown in FIG. 1, the valve seat 6 can be made from at least two materials of different stiffnesses, the less rigid material forming the contact zone of the valve seat 6 with the Valve member 1. Advantageously, said valve seat 6 comprises a hollow sleeve 61 made of rigid material, an end surface 62 of said sleeve 61 being covered with a less rigid synthetic material. Preferably, the rigid material forming the sleeve 61 is a synthetic material sufficiently rigid to withstand high pressures, and in particular to avoid any risk of deformation likely to impair the operation of the pressure reducer.

  Preferably, the synthetic materials of this sleeve 61 and this end surface 62 are chemically compatible. This can in particular be achieved by providing a synthetic material of the same type, to advantageously identical, but different hardness and / or modulus of elasticity (s). For example, one can consider using a thermoplastic elastomer material, such as polyurethane. The sleeve 61 may be reinforced by reinforcing means, such as glass fibers, while the end surface 62 does not comprise these reinforcement means or has less of them. Other materials are of course usable, the sleeve 61 and the end surface 62 not necessarily being formed from the same identical material.

  The advantages of this implementation are numerous. Thus, after assembly, in particular injection molding, the sleeve 61 and the end surface 62 form a single solid part eliminating any risk of delamination or detachment of the flexible portion 62 cooperating with the valve member 1. Indeed during the injection overmoulding step, the contacting surfaces melt and intimately bond to each other, so that the sleeve 61 and the end surface 62 then behave as if they were of a monobloc part. The present invention thus completely eliminates the use of any binding agent between these two elements 61 and 62. The present invention also makes it possible to choose an ideal material hardness for the zone of sealed contact with the valve element as well as ideal material stiffness for the sleeve 61. Moreover, particularly in the example of Figure 1, in case of wear of the end surface 62 of less rigid synthetic material, the high pressure would in any case act against the sleeve 61 t0 of rigid synthetic material, which is not metal, and which is therefore capable of substantially limiting the flow of high pressure gas. Alternatively, one can also provide a valve seat 6 made of a single material, preferably a synthetic material rigid enough to withstand high pressures, but less rigid than the metal, thus promoting a good seal in the closed position of the valve.

  According to an advantageous embodiment, represented in FIGS. 1 and 2, the valve element 1 cooperates, in the closed position, with a flat part of an end surface of the sleeve 61. For this purpose, the element valve member 1 to comprise at least one projection extending axially from said enlarged head. This projection advantageously forms a crown tip, but any other suitable form is conceivable. Preferably, said tip is not sharp to avoid damaging the end surface of the valve seat 6. It should be noted that FIG. 2 shows a valve seat 6 made of a single material. It is understood that this implementation is also applicable to the embodiment of Figure 1. In this case, the rigid synthetic material forming the valve seat 6 cooperates with the rigid synthetic material forming the portion of the valve member 1 in contact with the valve seat in the closed position. This contact between two synthetic materials makes it possible to obtain a good seal.

  Alternatively, the valve member could cooperate in the closed position with an end edge of the sleeve. In particular, the sleeve could be substantially tubular by forming an internal passage extending between upstream and downstream end edges in the direction of gas flow.

  The valve member would then preferably cooperate with said upstream end edge. Advantageously, the valve member would then have a contact surface for cooperating with said end edge. This contact surface could be of any suitable shape. This contact surface could advantageously be formed on a central axial projection extending from said enlarged head of the valve element. >>

  The present invention thus makes it possible to eliminate the disadvantages of the various pressure reducers disclosed by the prior art, and provides a valve element and a valve seat that are simple and reliable, which are adaptable to any type of existing pressure reducer, and which are inexpensive to manufacture and to assemble.

  Although the above description has been made with reference to several particular embodiments of the present invention, it is understood that one skilled in the art can make any useful modifications without departing from the scope of the present invention as defined by the appended claims.

Claims (19)

claims   L-Balanced pressure reducer, especially for high or very high pressure gases, comprising a body (7) defining a high pressure inlet (10) and a low pressure outlet (11), a valve element (1) being disposed between said high pressure inlet (10) and said low pressure outlet (11), said valve element (1) being movable between an open position, into which it opens a passage between said high pressure inlet (10) and said low outlet pressure (11), and a closed position, in which it cooperates with a valve seat (6) to seal said passage, characterized in that said valve member (1) is made of two different materials, and comprises a hollow central body (2) made of hard material and resistant to very high pressures, such as metal, said central body (2) being at least partially covered with a layer (3) made of rigid, hard and resistant to abrasion.   2. A pressure reducer according to claim 1, wherein the portion of the valve member (1) in contact with said valve seat (6) is formed on said layer (3).   3. A pressure reducer according to claim 1 or 2, wherein said layer (3) is molded on said central body (2).   4. A pressure reducer according to any one of the preceding claims, wherein said central body (2) has a substantially cylindrical shape.   5. A pressure reducer according to any one of the preceding claims, wherein said valve member (1) has, in cross section, a T-shaped shape comprising a hollow stem and an enlarged head, said head being provided with at least one projection comprising the zone of the valve member (1) cooperating with said valve seat (6).   6. A pressure reducer according to claim 5, wherein said enlarged head is formed by said layer (3).   7. A pressure reducer according to any one of the preceding claims, wherein said valve member (1) comprises at least one projection (101, 102) cooperating with said valve seat (6) in the closed position.   A pressure reducer as claimed in any one of the preceding claims, wherein the valve seat (6) forms a substantially tubular hollow structure having an internal passage (65) and defining an end surface (62), said element valve member (1) cooperating in a closed position with any point of said end surface (62).   9. A pressure reducer according to claim 8, wherein said valve member (1) comprises at least one projection (102) comprising a non-cutting contact tip cooperating with any point of said end surface (62). the valve seat (6).   10. A pressure reducer according to any one of the preceding claims, wherein said valve seat (6) comprises a sleeve (61) made of a rigid synthetic material.   11. A pressure reducer according to any one of the preceding claims, wherein said valve seat (6) is made from at least two materials of different stiffnesses, the material of lesser rigidity forming the contact zone of said seat valve member (6) with said valve member (1) in the closed position.   12. A pressure reducer according to claims 10 and 11, wherein an end surface (62) of said sleeve (61) is coated with a less rigid synthetic material cooperating with said valve member (1) in the closed position. .   13. A pressure reducer according to claim 12, wherein said end surface (62) is overmolded onto said sleeve (61), especially by injection molding.   14. A pressure reducer according to claim 12 or 13, wherein the synthetic materials forming said sleeve (61) and said end surface (62) are chemically compatible and of different hardness and / or modulus of elasticity (s). ).   15. A pressure reducer according to any one of claims 12 to 14, wherein the synthetic materials forming said sleeve (61) and said end surface (62) are of the same type, such as a thermoplastic elastomer.   16. A pressure reducer according to any one of claims 13 to 15, wherein said sleeve (61) and said end surface (62) are formed from the same synthetic material, such as a thermoplastic elastomer, in particular polyurethane, said sleeve (1) being reinforced by reinforcing means, such as glass fibers.   17. A pressure reducer according to any one of claims 13 to 16, wherein, after molding, said sleeve (61) and said end surface (62) are intimately connected to each other, said link resistant to high pressures.   18. A pressure reducer according to any one of the preceding claims, wherein said valve member (1) is moved to its open position by a control member (14) which, when the gas pressure is less than a predetermined pressure threshold is biased by a first elastic element (13), such as a spring, towards an actuating position corresponding to the opening position of the valve element (1), said first elastic element (13), from said predetermined pressure threshold, no longer biasing said control member (14) towards its actuating position so that said valve member (1) is then elastically biased towards its closed position by a second resilient member (20), such as a spring.   19. A pressure reducer according to claim 18, wherein said control member (14) is separated from said first elastic member (13) by a membrane (12).