Pressure balance valve

Abstract

The present invention relates to a pressure balancing valve comprising: a valve body; a cover; a cage body defining a sliding seat; a closing member movable in the sliding seat between a closed position in which the lateral opening of the cage body is closed and a fully open position in which the lateral opening of the cage body is fully free; a rod; and a sealing assembly. The seal assembly includes: at least one seal ring disposed about a first cylindrical portion of the closure member and contacting a first cylindrical portion of the sliding seat, where the first cylindrical portion of the sliding seat is axially bounded by a first abutment surface, and where the first cylindrical portion of the closure member is axially bounded by a second abutment surface; at least one thrust annular flange comprising an annular edge; and an elastic device. The abutment surface is defined such that when the closure member moves toward the closed position, the at least one sealing ring abuts the first abutment surface at a side opposite the side contacting the annular edge before the closure member reaches the closed position.

Description

Technical Field

[0001] The present invention generally falls within the field of the construction of pressure balance valves. In particular, the present invention relates to a pressure balance valve having a new dynamic sealing system. In particular, the valve according to the present invention can be a control valve or alternatively a shut-off valve. Background Art

[0002] The use of valves provided with a pressure balance system, in particular control valves, is known. Among these, a "ball" type balance valve provided with a valve body is known, in which an inner cavity for the fluid flow between a fluid inlet section and a fluid outlet section is defined. Inside the inner cavity, a cage-like body is arranged which defines a sliding seat for a closing member. The cage-like body includes an opening for the fluid flow towards the fluid outlet section.

[0003] A rod projecting from the valve body through an access opening closed by a cover is rigidly connected to the closing member. The rod can be moved by an actuating device of linear or rotary type. By means of the rod, the closing member can be moved between a closed position and a fully open position, in which the fluid flow through the opening of the cage-like body is completely inhibited by the closing member, and in the fully open position, the said opening of the cage-like body is completely free, thus allowing the maximum fluid flow rate. The flow rate is regulated by changing the position of the closing member between the closed position and the fully open position, i.e., by changing the degree of closing / opening of the opening of the cage-like body.

[0004] In a balanced ball valve, the closing member includes one or more pressure balance channels. These channels extend between a first surface of the closing member facing the fluid entering the valve and a second surface to which the rod of the closing member is connected. When the closing member is in the closed position, these channels put into communication a first part of the inner cavity defined between the fluid inlet port and the first surface with a second part of the inner cavity defined between the cover and the second surface, where neither of these parts communicates with the fluid outlet section. By means of the channels, an equilibrium of the pressures in the aforementioned two cavity parts is obtained. Thus, keeping the dimensions of the closing member and the fluid flow rate the same, the force that must be applied by the actuating device to the rod in a balanced valve to keep the closing member in the closed position is much lower compared to the force required in an unbalanced valve. For this reason, pressure balance valves are particularly useful when the valve size becomes very large.

[0005] In order for the valve to function correctly when the closing member is in the closed position, the fluid sealing system between the cage-like body and the closing member is crucial. This sealing system is of the dynamic type, since the closing member moves inside the cage-like body and thus moves relative to the cage-like body.

[0006] According to a first known solution, the fluid sealing system comprises lip seals actuated by mechanical elements within each of the seals. The lip seals can be made of, for example, PTFE and include a mechanical spring made of stainless steel inside the lip seals. This type of seal is typically received in an annular seat formed in the outer surface of the closing member and / or in the inner surface of the cage body. Due to the action of the inner spring, the seal always remains in contact with the surfaces of the two components even in the valve open state (i.e., when the closing member is not in the closed position). Therefore, the seal is subject to continuous wear and thus has a very limited service life.

[0007] According to another known solution, the sealing system is based on one or more seals made of graphite. In addition to experiencing very high wear (and thus having a very short service life), these seals also require complex fitting operations because they must be pre-actuated in the corresponding fitting seats. Furthermore, further wear of these seals releases graphite particles that contaminate the system in which the valve is located. In applications where a high degree of cleanliness is required, the use of graphite seals is actually not feasible.

[0008] Therefore, the applicant has recognized the need to provide a new, more effective and durable solution for ensuring the seal between the cage body in a pressure balance valve and a closing member that can move within the cage body. Summary of the Invention

[0009] In view of the above, the main object of the present invention is to provide a pressure balance valve that allows solving or at least alleviating the problems of the prior art.

[0010] Within this object, a first object of the present invention is to provide a pressure balance valve having improved sealing characteristics between the cage body and the closing member.

[0011] Another object of the present invention is to provide a pressure balance valve in which the seal between the cage body and the closing member does not require complex operations for fitting and / or actuating the sealing ring.

[0012] An important object of the present invention is to provide a pressure balance valve that is reliable and easy to manufacture and assemble at a competitive cost.

[0013] What the applicant has found is that the above-indicated objects and purposes can be achieved by providing a sealing assembly including a sealing ring disposed between the closing member and the cage body, the sealing ring being held compressed between an abutment surface defined by the cage body and a thrust flange that is connected to the closing member in a floating manner and is subject to the action of an elastic device during the final stage of the closing movement of the closing member. The sealing ring is mechanically actuated each time the valve is closed and loses the actuated state of the sealing ring when the valve is partially or fully opened.

[0014] In particular, the above-indicated objects and purposes are achieved by a pressure balance valve, which comprises:

[0015] - A valve body, which includes a fluid inlet port and a fluid outlet port. Wherein, the valve body defines a cavity that communicates the fluid inlet port with the fluid outlet port, and wherein the cavity can be accessed through a top access opening of the valve;

[0016] - A removable cover that closes the top access opening;

[0017] - A cage body, which is arranged in the cavity and associated with the valve body in a fixed position. Wherein, the cage body defines a sliding seat for a closing member, and wherein the cage body includes at least one lateral opening for fluid flow;

[0018] - A closing member, which is capable of moving in the sliding seat between a closed position in which the lateral openings of the cage body are closed and a fully open position in which the lateral openings of the cage body are completely free. Wherein, the closing member includes at least one pressure balance channel extending between a first surface and a second surface of the closing member. Wherein, the channel communicates a first part of the cavity defined between the fluid inlet port and the first surface of the closing member with a second part of the cavity defined between the cover and the second surface of the closing member;

[0019] - A rod, which includes a first end connected to the closing member at the second surface and a second end connected to the actuating device of the valve. Wherein, the rod extends through the second part of the cavity;

[0020] - A sealing assembly, which provides a fluid seal between the second part of the cavity and a third part of the cavity that communicates with the outlet port.

[0021] According to the present invention, the sealing assembly comprises:

[0022] - At least one sealing ring, which is arranged around a first cylindrical part of the closing member and contacts a first cylindrical part of the sliding seat of the cage body. Wherein, the first cylindrical part of the sliding seat is axially defined by a first abutting surface, and wherein the first cylindrical part of the closing member is axially defined by a second abutting surface;

[0023] - At least one thrust annular flange, which is arranged in the second part of the cavity in a position adjacent to the second surface of the closing member. Wherein, the thrust flange includes an annular edge that contacts a first surface of the at least one sealing ring, and wherein the thrust annular flange floats axially relative to the closing member;

[0024] - An elastic device that pushes the annular flange towards the second surface of the closing member.

[0025] Furthermore, according to the present invention, the abutment surface is defined such that when the closing member moves towards the closed position, the at least one sealing ring abuts against the first abutment surface at a side opposite to the side in contact with the contact annular edge before the closing member reaches the closed position.

[0026] Preferably, the at least one sealing ring has no actuating elastic insert.

[0027] According to an embodiment, the sealing assembly includes a plurality of sealing rings arranged in a encapsulated configuration, wherein, when the closing member moves towards the closed position and before the closing member reaches the closed position, the sealing rings abut against the first abutment surface, and wherein another sealing ring contacts the annular edge of the thrust flange.

[0028] According to another embodiment, the sealing assembly includes a plurality of sealing rings arranged in a encapsulated configuration, wherein a first outer sealing ring contacts the first sealing surface or the second sealing surface, and a second outer sealing ring is contacted by the annular edge of the thrust flange; the plurality of sealing rings includes at least one central sealing ring in contact with the first outer sealing ring and in contact with the second outer sealing ring.

[0029] Preferably, the plurality of sealing rings includes two central sealing rings in contact with each other, wherein each central sealing ring contacts one of the outer sealing rings.

[0030] Preferably, the sealing ring has a cross-section with a substantially trapezoidal shape, wherein the cross-section is evaluated in a radial sectional plane.

[0031] According to an embodiment of the present invention, the thrust flange includes a planar portion having an annular shape, and the annular edge projects from an end of the planar portion in a direction substantially perpendicular to the reference plane in which the planar portion extends.

[0032] Preferably, the thrust flange is axially floatingly coupled to the closing member by means of a plurality of coupling pins protruding from the second surface of the closing member, wherein each coupling pin extends through an opening formed in the planar portion of the thrust flange.

[0033] According to a possible embodiment of the present invention, the elastic device includes a plurality of springs, each of the plurality of springs being arranged around one of the coupling pins so as to be axially interposed between the stop flange and a stop device fixed to the coupling pin, wherein the thrust flange is positioned between the spring and the second surface of the closing member.

[0034] Preferably, the stop device includes at least one nut screwed onto the free end of the corresponding coupling pin.

[0035] According to a possible embodiment of the present invention, the closing member includes a second cylindrical portion having a diameter greater than that of the first cylindrical portion, and wherein the sliding seat portion of the cage body includes a second cylindrical portion having a diameter smaller than that of the first cylindrical portion of the sliding seat portion; the second cylindrical portion of the closing member contacts the second cylindrical portion of the sliding seat portion.

[0036] According to a possible embodiment, the valve includes a valve body extension that is connected to the valve body at the top inlet opening, wherein the valve body extension defines the inlet opening of the valve, wherein the inlet opening is closed by a lid, and the valve body extension is traversed by a rod and defines an inner cavity having an annular shape, and a heat insulation assembly is removably received in the inner cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other features and advantages of the present invention will become more readily apparent from the following detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings, in which:

[0038] Figure 1 is a longitudinal sectional view of a first embodiment of a valve according to the present invention in a first operating configuration;

[0039] Figure 2 is Figure 1 an enlarged view of detail II of

[0040] Figure 3 is of Figure 1 the valve in a second operating configuration in another longitudinal sectional view;

[0041] Figure 4 is Figure 3 an enlarged view of detail IV of

[0042] Figure 5 is Figure 1 the valve in another longitudinal sectional view during valve closing;

[0043] Figure 6 is Figure 5 an enlarged view of detail VI of

[0044] Figure 7 is Figure 6 an enlarged view of detail VII of

[0045] Figure 8 is Figure 1 a perspective view of the component assembly of the valve;

[0046] Figure 9 is Figure 8 an exploded perspective view of the component assembly;

[0047] Figure 10 is Figure 8 a longitudinal sectional view of a component assembly;

[0048] Figure 11 is of Figure 1 a valve in a first assembly step;

[0049] Figure 12 is of Figure 1 a valve in a second assembly step;

[0050] Figure 13 is a longitudinal sectional view of another embodiment of a valve according to the present invention;

[0051] Figure 14 and Figure 15 are partial cutaway perspective views of other embodiments of a valve according to the present invention.

[0052] Like reference numerals and letters in the drawings denote like elements or components. DETAILED DESCRIPTION

[0053] The present invention relates to a pressure balancing valve, wherein the valve can be a control valve or alternatively a shut-off valve. Figures 1 to 12 Relates to a valve (generally denoted by reference numeral 1) according to the present invention, which valve can be used to control the flow rate of a fluid. Figure 13 Also relates to a valve having an extended configuration particularly intended for controlling convection / flow rate in cryogenic applications, wherein, in this context, "cryogenic application" refers to an application where the operating temperature needs to be less than or equal to -150 °C (123 K). Figure 14 Relates to another embodiment of a pressure balancing valve according to the present invention that can be used as a control valve; finally, Figure 15 shows an embodiment of a pressure balancing valve according to the present invention that can be used as a shut-off valve.

[0054] Referring to Figures 1 to 12 , valve 1 includes a valve body 2 having a fluid inlet port 211 and a fluid outlet port 212. The valve body 2 includes a lumen 20 extending between the fluid inlet port 211 and the fluid outlet port 212 to put them in communication. The valve body 2 is preferably made as one piece, and the configuration of the valve body 2 generally corresponds to that of a "ball" type control valve.

[0055] The fluid inlet port 211 and the fluid outlet port 212 have a common axis X-X. Alternatively, the ports 211, 212 can be defined such that their respective axes are parallel but do not coincide (i.e., such that they do not have a common axis).

[0056] The valve body 2 includes an inlet opening 213 for entering the chamber 20. In the illustrated embodiment, the inlet opening 213 has a longitudinal axis Y-Y that is substantially orthogonal to the axis X-X of the other mentioned openings 211, 212. Alternatively, the longitudinal axis Y-Y may not be orthogonal to the axis X-X. Hereinafter, the terms "axial" and "axially" refer to a state parallel to the longitudinal axis Y-Y, while the terms "transverse" and "transversely" denote a state orthogonal to the said longitudinal axis Y-Y.

[0057] The valve 1 includes a cylindrical cage-like body 40 disposed inside the chamber 20 of the valve body 2. More precisely, the cage-like body 40 is coupled to the valve body 2 so as to maintain a fixed position within the chamber 20, i.e., a fixed position relative to the same valve body 2.

[0058] The cage-like body 40 defines a cylindrical sliding seat portion 43 (clearly visible in Figure 11 ), in which the closing member 3 of the valve 2 can translate. At least a portion of the sliding seat portion 43 defines a guide for the axial movement of the closing member 3. The cage-like body 40 includes at least one lateral opening 46 (preferably a plurality of lateral openings 46) for the fluid flow. In detail, each lateral opening 46 allows the fluid to flow between the volume inside the cylindrical sliding seat portion 43 (communicating with the fluid inlet port 211) and the volume outside the cage-like body 40 (communicating with the fluid outlet port 212).

[0059] The valve 1 includes a cylindrical closing member 3 slidably disposed in the sliding seat portion 43 of the cage-like body 40. Thus, the closing member 3 is coaxial with the cage-like body 40 and can slide along the longitudinal axis Y-Y indicated above. More precisely, the closing member 3 is capable of moving in the sliding seat portion 43 between a closed position (shown in Figure 5 and Figure 6 ) and a fully open position (shown in Figure 1 and Figure 2 ).

[0060] When the closing member 3 is in the closed position, the fluid entering the valve cannot flow through the lateral openings 46 of the cage-like body 40, such that the fluid flow rate at the fluid outlet port 212 is zero (i.e., the output flow rate leaving the valve is zero). When the closing member 3 is in the fully open position, the entire fluid flow can flow through the lateral openings 46 and reach the fluid outlet port 212. The flow control is achieved by translating the closing member 3 to an intermediate position between the closed position and the fully open position. Basically, the output flow rate depends on the position of the closing member 3 relative to the lateral openings 46 of the cage-like body 40.

[0061] The closing member 3 is provided with at least one passage 51 extending between its first surface 311 and second surface 312. Preferably, these surfaces 311, 312 are transverse to the longitudinal axis Y-Y. The at least one passage 51 puts into communication a first part 21 of the inner cavity 20 of the valve body 2 with a second part 22 of the inner cavity 20. In particular, the first part 21 is delimited between the fluid inlet port 211 and the first surface 311 of the closing member 3, while the second part 22 is delimited between the cover 5 of the valve 2 and the second surface 312 of the closing member 3. In the case where the closing member 3 is in the closed position, the fluid pressure between the first part 21 and the second part 22 of the inner cavity 20 is balanced by means of this passage 51. Hereinafter, the second part 22 of the inner cavity will also be denoted as the squeeze balancing chamber 22.

[0062] According to the preferred embodiment shown in the figures, the closing member 3 comprises a plurality of pressure balancing passages 51 extending between the first surface 311 and the second surface 312 of the closing member as described above. Preferably, these passages 51 extend parallel to the longitudinal axis Y-Y and have a substantially circular cross-section. These passages 51 also extend along (having a diameter represented by the reference numeral dr in Figure 12 the figures) a circumference and are angularly spaced from each other (see, for example, Figure 9 ).

[0063] The valve 1 according to the invention further comprises a rod 6 provided with a first end 61 which is connected to the closing member 3 at the above-mentioned second surface 312. The second end 62 of the rod 6 projects from the cover 5 of the valve and is connected to an actuating device which comprises a motor, a handwheel or any other device known to the person skilled in the art and capable of being used to move the rod 6 along the longitudinal axis Y-Y. In Figure 1 the figures, these actuating devices are schematically shown as a box indicated by the reference numeral 600.

[0064] The valve 1 comprises a sealing assembly 60 which is configured to ensure a fluid seal between the sliding seat 43 of the cage-shaped body 40 and the closing member 3 in the case where the closing member 3 is in the closed position. Basically, the sealing assembly 60 is configured to provide a seal between the balancing chamber 22 of the inner cavity 20 and a third part 23 which extends around the cage-shaped body 40 and is in communication with the fluid outlet port 212 when the valve is closed. In the case where the valve is closed (i.e., in the case where the closing member 3 is in the closed position), this third part 23 of the inner cavity 20 is not hydraulically in communication with the first part 21 of the cavity 20 defined above.

[0065] Referring to Figure 1, the sealing assembly 60 includes a plurality of sealing rings 61, 62, 63, 64 which are arranged around the closing member 3, more precisely arranged such that the inner cylindrical surfaces Si of these sealing rings (as Figure 10 shown) contact the surface of the first cylindrical portion of the closing member 3 in order to form an "encapsulated" sealing structure. The sealing rings 61, 62, 63, 64 contact the surface of the first cylindrical portion 431 of the sliding seat 43 at their outer cylindrical surfaces Se (as Figure 10 shown). Thus, the two cylindrical portions 331, 431 mentioned above have different diameters (shown as D2 and D2* respectively in Figure 10 and Figure 11 ), thereby defining an annular seat 611 in which the sealing rings 61, 62, 63, 64 are arranged.

[0066] The first cylindrical portion 431 of the sliding seat 43 at least partially defines the pressure balance chamber 22 mentioned above. The first cylindrical portion of the closing member 2 extends from the second surface 312 of the closing member. The first cylindrical portion 431 is axially bounded by a first abutment surface 66A which is preferably inclined with respect to the longitudinal axis Y - Y, and even more preferably inclined at an angle of 45°. The first cylindrical portion 331 of the closing member 33 is axially bounded by a second abutment surface 66B which preferably extends orthogonally to the longitudinal axis Y - Y.

[0067] The two surfaces 66A, 66B define an abutment portion for the encapsulated sealing structure formed by the sealing rings 61, 62, 63, 64. More precisely, depending on the operating conditions of the valve, in particular depending on the axial position occupied by the closing member 3, one of the sealing rings (indicated by the reference numeral 61) contacts the abutment surfaces 66A, 66B, as will be better explained below.

[0068] According to the invention, the sealing assembly 60 includes a thrust annular flange 68 (also simply referred to as flange 68 hereinafter) which is arranged in the balance chamber 22 of the inner cavity 20 in a position adjacent to the second surface 312 of the closing member 3. The thrust flange 68 includes an annular edge 69 which is at least partially inserted into the annular seat 611. This annular edge 69 contacts the sealing ring element of the encapsulated sealing structure (indicated by the reference numeral 64). In particular, the flange 68 is coupled to the closing member 3 so as to be axially floating relative to the closing member itself. The state of "axial floating" means that the flange 68 is axially pulled together with the closing member 3, but retains translational freedom relative to the closing member 3 in a direction parallel to the longitudinal axis Y - Y.

[0069] The sealing assembly 60 further includes an elastic means 65 which acts on the flange 68 so as to push the flange 68 towards the second surface 312 of the closing member 3. More precisely, the elastic means 65 exerts a force on the flange 68 such that the annular edge 69 remains in contact with the encapsulated sealing structure (in particular with the sealing ring 64).

[0070] According to the invention, two abutment surfaces 66A, 66B are defined such that the encapsulated sealing assembly, in particular the first sealing ring 61, abuts against the first abutment surface 66A before the closing member 3 reaches the closed position. In this way, during the subsequent travel of the closing member 3 towards the closed position, the sealing rings 61, 62, 63, 64 are kept compressed between the first abutment surface 66A (fixed with respect to the inner cavity 20) and the annular edge 69 of the flange 68 (capable of moving in the axial direction), and thus expand in the annular seat 611, thereby creating a seal.

[0071] In other words, in the last stage of the travel of the closing member 3, the sealing rings 61, 62, 63, 64 are further excited by coming into contact with the first abutment surface 66A. Thus, unlike the prior art solutions, the excitation of the sealing rings occurs mechanically when and only when the closing member 3 enters the closed position.

[0072] Figure 3 and Figure 4 shows the closing member 3 at the position where the excitation of the sealing rings 61, 62, 63, 64 starts. It can be noted that at this position, the two abutment surfaces 66A, 66B are at approximately the same height relative to Figure 4 and Figure 6 the plane indicated by PC in. The plane PC is the plane at which the closing member 3 reaches the fully closed position.

[0073] With particular reference to Figure 6 and Figure 7 , according to a possible and thus non - exclusive embodiment, the sealing assembly 60 includes four sealing rings 61, 62, 63, 64. In particular, two outer sealing rings (indicated by the reference numerals 61 and 64) and two central sealing rings (indicated by the reference numerals 62 and 63) positioned between the outer sealing rings can be identified. During the assembly of the valve, considering the sealing rings 61, 62, 63, 64, their inner diameters correspond to the diameter D2 of the first cylindrical surface 331 of the closing member 3 (see Figure 10 ). Thus, the sealing rings 61, 62, 63, 64 are arranged around the first cylindrical surface 331 of the closing member 3 and are always positioned between the second abutment surface 66B and the flange 68 with respect to the closing member 3 (as can be understood from Figure 8 ).

[0074] Depending on the operating conditions of the valve, the first outer sealing ring (reference numeral 61) contacts one of the two abutment surfaces 66A, 66B defined above. Due to the thrust force exerted by the elastic means 65 on the flange, the other outer sealing ring (reference numeral 64) always contacts the annular edge 69 of the flange 68. The two central sealing rings 62, 63 contact each other and each contact one of the outer sealing rings 61, 64 so as to form the encapsulated sealing structure mentioned above.

[0075] Preferably, each of the sealing rings 61, 62, 63, 64 has a trapezoidal cross-section, which is evaluated in a radial cross-sectional plane passing through the axis of the ring. Preferably, the two sealing rings (indicated by reference numerals 61 and 62 respectively) at the end of the encapsulated sealing structure have cross-sections similar to a right trapezoid, while the two central rings 62, 63 have cross-sections similar to an isosceles trapezoid. Considering the encapsulated structure in the radial cross-sectional plane, the sealing rings 61, 62, 63, 64 are arranged such that each sealing ring contacts the adjacent ring at the inclined side of its cross-section.

[0076] When the closing member reaches the position where actuation starts ( Figure 3 and Figure 4 ), the sealing rings 61, 62, 63, 64 are axially forced against the first abutment surface 66A on one side and against the annular edge 69 of the flange 68 on which the elastic means 65 acts on the other side. The first abutment surface 66A prevents the sealing rings 61, 62, 63, 64 from moving together with the closing member 3 towards the closed position. This situation causes the radial expansion of all the sealing rings 61, 62, 63, 64 in the annular seat 611. The trapezoidal cross-sectional shape of the sealing rings 61, 62, 63, 64 optimizes this expansion effect and thus optimizes the final seal.

[0077] In an alternative embodiment, the sealing assembly 60 may include a different number of sealing rings from the number of sealing rings mentioned above. Also, the configuration of the rings (i.e., the configuration of the radial cross-section) may also be different from the configuration shown and described in the figure, as long as it is still suitable for the purpose. In a possible embodiment, for example, the sealing assembly may also include only one sealing ring, which is provided with a first surface intended to contact the abutment surfaces 66A, 66B and a second surface opposite to the first surface, and the second surface remains in contact with the annular edge 69. In this case, when reaching the position where actuation starts, the first abutment surface 66A acts on the first surface of the single sealing ring, thereby preventing the sealing ring from moving axially. Therefore, the subsequent movement of the closing member 3 causes the ring to be actuated according to the same principle as described above.

[0078] According to the preferred embodiment shown in the figures, the flange 68 includes a planar portion 68A having an annular shape, and an annular edge 69 projects at the outermost end of the planar portion 68A. In particular, the annular edge 69 extends in a direction orthogonal to the reference plane R-R (shown in Figure 10 ), and the planar portion 68A extends in the reference plane R-R. Preferably, the outermost diameter de (shown in Figure 10 ) of the planar portion 68A is substantially close to the inner diameter D2* (shown in Figure 11 ) of the first portion 431 of the cylindrical seat 43 of the cage body 40. In any case, the flange 68 is free to move relative to the cage body 40 when pulled by the closing member 3.

[0079] However, the inner diameter d2 (shown in Figure 10 ) of the planar portion 68A is larger than the diameter (shown by dr in Figure 12 ) of the reference circumference considered in a plane transverse to the longitudinal axis Y-Y (at the second transverse surface 312 of the closing member 3), and all the pressure balance channels 51 are included within the inner diameter d2. In other words, the planar portion 68A is configured such that these channels 51 are not blocked to allow fluid to reach the balance chamber 22.

[0080] The flange 68 is connected to the closing member 3 by a plurality of connection pins 75. Preferably, each pin 75 is screwed onto the body of the closing member 3 at the second surface 312. Each pin 75 extends through a corresponding opening 68B formed in the planar portion 68A of the flange 68.

[0081] In this embodiment, the elastic means 65 includes a plurality of springs (also denoted by the reference numeral 65), in particular Belleville washers, and each spring is inserted onto one of the connection pins 75 so as to be axially arranged between the flange 68 and the stop means 78 fixed to the connection pins 75. In fact, one end of each spring 65 abuts against the flange 68, while the other end abuts against the stop means 78.

[0082] Preferably, for each connection pin 75, the corresponding stop means 78 includes a nut 78A which is screwed onto the end of the connection pin 75 opposite to the end screwed onto the closing member 3. For each connection pin 75, the corresponding stop means 78 further includes a washer 78B inserted between the nut 78A and the corresponding spring 65.

[0083] Referring to Figure 1 and Figure 7 , the operating principle of the valve 1 according to the present invention, in particular the operating principle of the sealing assembly 60, will be described below. Referring to Figure 1 and Figure 2, in the (fully or partially) open state of the valve, fluid flows through the lateral openings 46 of the cage body 40 and exits from the fluid outlet port 212 of the valve body 1. Obviously, the flow rate depends on the position of the closing member 3 relative to the lateral openings 46 of the cage body 40. In this case, no sealing is required between the cage body 40 and the closing member 3.

[0084] In the fully open state of the valve, the first outer ring 61 contacts the second abutment surface 66B, while the second outer sealing ring 64 contacts the annular edge 69 of the flange 68. As a whole, the sealing rings 61, 62, 63, 64 are subject to the thrust force exerted by the elastic means 65 on the flange 68. The closing member 3 is in such a position that the second abutment surface 66B is at a greater axial distance from the closing plane PC than the first abutment surface 66A.

[0085] The movement of the closing member 3 towards the closed position causes the second abutment surface 66B to gradually move towards the first abutment surface 66A until it reaches the state clearly visible in Figure 4 , whereby the two abutment surfaces 66A, 66B are substantially at the same height relative to the closing plane PC. In this state achieved before the closing member 3 reaches the closed position, the first outer sealing ring 61 contacts the two abutment surfaces 66A, 66B.

[0086] Therefore, in order to obtain a complete closure from the Figure 3 position shown, the closing member 3 still has to execute the last part of its stroke S (as shown in Figure 4 ). By acting on the first outer sealing ring 61, the first abutment surface 66A prevents the encapsulated sealing structure from moving in the axial direction. When the closing member 3 starts to execute the said last part of its stroke S, the sealing rings 61, 62, 63, 64 are excited because they are compressed between the first abutment surface 66A and the annular edge 69 of the flange 68; this compression causes the sealing rings to expand in the annular seat 611.

[0087] As shown in Figure 5 and Figure 6 , when the closing member 3 reaches the closed position (the plane PC shown in Figure 4 and Figure 6 ), the excitation of the sealing rings 61, 62, 63, 64 is completed. In this case, the second abutment surface 66B is located at an axial position closer to the closing plane PC than the first abutment surface 66A.

[0088] The excitation of the sealing rings 61, 62, 63, 64 is mechanical because it is obtained by the mechanical action performed by the first abutment surface 66A on one side and the mechanical action performed by the flange 68 on the other side during the last stage of the movement of the closing member 3 towards the closed position. Advantageously, whenever the closing member 3 reaches the fully closed position, the excitation of the sealing rings 61, 62, 63, 64 occurs automatically.

[0089] When the closing member 3 moves from the closed position towards the fully open position, when reaching Figure 4 the state where the action performed by the first abutment surface 66A on the sealing rings 61, 62, 63, 64 stops, and the sealing rings 61, 62, 63, 64 are subjected to the sole action of the flange 68 pushed by the elastic means 65.

[0090] Referring to Figure 7 the detailed view of

[0091] According to the above, the sealing rings 61, 62, 63, 64 can be made of plastic material (such as PTFE or PEEK) without the need to include springs or other excitation elements in their structure. As described above, in the case of valve opening, the pressure in the balance chamber is minimal, and the sealing rings 61, 62, 63, 64 are actually only subjected to the thrust exerted by the elastic means 65 via the flange 68. Therefore, the sealing rings 61, 62, 63, 64 are not actually excited during the valve regulation phase, that is, when the closing member moves relative to the cage body 40. Therefore, the wear of the sealing rings 61, 62, 63, 64 is greatly reduced, that is, the service life of the rings is advantageously increased.

[0092] According to the preferred embodiment shown in the figure, the cylindrical body of the closing member 3 has a cavity 33, the bottom of which defines the first surface 311 of the closing member, and the passage 51 for pressure balance extends from this first surface. As can be easily seen from the figure, this cavity 33 gives the closing member a partially hollow configuration. At the same time, the cavity 33 allows the closing member 3 to be lightened and thus limits the total weight of the valve.

[0093] The closing member 3 includes a second outer cylindrical portion 332 having a diameter (designated D1) greater than that of an adjacent first cylindrical portion 331 (designated D2), the first cylindrical portion 331 partially defining an annular seat 611 in which sealing rings 61, 62, 63, 64 are arranged (see Figure 10 ). The sliding seat 43 is defined by a second cylindrical portion 432 of the cage-like body 40 adjacent to the above-mentioned first cylindrical portion 431. The diameter (designated D1* in Figure 11 ) of the second cylindrical portion 432 corresponds to the diameter (designated D1 in Figure 10 ) of the second cylindrical portion 332 of the closing member 3, where the two diameters (D1 and D1*) define a connection that allows the closing member 3 to translate in the sliding seat 43.

[0094] As is clearly visible from the figure, the closing member 3 preferably includes a third outer cylindrical portion 333 that is included between the first cylindrical portion 331 and the second cylindrical portion 332. The diameter D3 of the third outer cylindrical portion 333 (see Figure 10 ) is greater than the diameter of the first outer cylindrical portion 331 and less than the diameter of the second outer cylindrical portion 332. The axial extension of the third outer cylindrical portion 333 is, instead, greater than the diameters of the other two outer cylindrical portions 331, 332. With this solution, only the second portion 332 of the closing member 3 (i.e., the portion with a limited axial extension) advantageously contacts the second portion 432 of the sliding seat 43.

[0095] According to the preferred embodiment shown in the figure, the position of the cage-like body 40 in the cavity 20 is fixed by a locking element 48. In particular, the positioning of the cage-like body 40 is carried out by inserting it through an access opening 213. When this insertion is complete, the locking element 48 is tightened (inside the cavity 20) so as to act on the second end portion 40B of the cage-like body 40, thereby fixing the cage-like body 40 in place.

[0096] The inner cavity 20 defines a seat 222 (shown in Figure 11 ), on which an annular support element 49 is positioned, and the cage-like body 40 is coaxially supported on the annular support element 49. The annular element 49 defines a closing plane PC, i.e., the closing position of the closing member 3. Preferably, the closing member 3 includes a transverse surface 313 (as shown in Figure 10 ) that defines an entrance to the cavity 33. A bevel 313A is defined between the second cylindrical portion 332 of the closing member 3 and the transverse surface 313, and the bevel 313A cooperates with a conical surface 49A (shown in Figure 2 ) of the support element 49 for sealing between the first portion 21 and the third portion 23 of the inner cavity 20 defined above.

[0097] Specifically referring to Figure 11 and Figure 12 , it can be noted that, with respect to the assembly / installation of the valve itself, the above-mentioned sealing assembly 60 is also very advantageous. In fact, the sealing assembly 60 is connected to the closing member 3 and is thus positioned within the valve body 2 together with it. The sealing rings 61, 62, 63, 64 are arranged between the second abutment surface 66B and the annular edge 69 of the flange 68 and are thus subjected to a preloading action performed only by the elastic means 65 alone.

[0098] From Figure 11 it can be easily seen that the closing member 3 connected to the sealing assembly 60 is first connected to the rod, and then the resulting component assembly (3, 60, 6) is connected to the valve body 2. In particular, after the cage-shaped body 40 has been fixed inside the valve body 2 by the locking ring 48, the closing member 3 and the sealing assembly 60 are inserted into the cage-shaped body 40 by means of the rod 6. Referring to Figure 12 , after the aforementioned component assembly (3, 60, 6) has been positioned, the access opening 213 can be closed by arranging the cover 5, thus defining the above-mentioned pressure balance chamber 22.

[0099] According to Figure 13 the embodiment shown, the valve (designated by the reference numeral 1') includes a valve body extension 4 arranged above the valve body 2. An inner chamber 400 is defined between the valve body extension 4 and the valve body 2. The inner chamber 400 and the valve body 2 can be accessed internally through the top access opening 50 of the valve 1', which is defined at the first end 410 of the valve body extension 4, the first end 410 being longitudinally opposite to the second end 415 that is connected to the valve body 2 at the access opening 213 of the valve body 2.

[0100] The top access opening 50 of the valve 1' is closed by the cover 5. The inner chamber 400 and the cover 5 are penetrated by the rod 6, and the closing member 3 located in the valve body is connected to the rod 6. The flange 51 defining the seat for the sealing plate 58 is connected to the said first end 410 of the valve body extension 4. The cover 5 is removably connected to the flange 51.

[0101] A bellows seal 9 surrounding the rod 6 is preferably arranged in the inner chamber 400. The bellows seal 9 includes a longitudinal end 9A fixed, for example welded, to the lower side of the sealing plate 58 and a second end fixed, for example welded, to a ring 91 that translates integrally with the rod 6.

[0102] Figure 13The valve 1' shown also includes a thermal insulation assembly 7 located between the valve body 2 of the valve 1' and the top inlet opening 50. The thermal insulation assembly 7 is removably received in the inner chamber 400. The thermal insulation assembly 7 has the function of thermally isolating a first region of the inner chamber 400 adjacent to the valve body 2 from a second region of the inner chamber 400 adjacent to the top inlet opening 50 and the cover 5. The first region is at a low temperature under operating conditions, while the second region can be at a higher temperature, such as ambient temperature, under operating conditions. In particular, the thermal insulation assembly 7 is configured to substantially limit the conductive heat exchange and convective heat exchange that may occur in the inner chamber 400 due to the temperature difference between the aforementioned two regions.

[0103] The thermal insulation assembly 7 includes a receiving chamber 71 having a cylindrical annular shape. The receiving chamber 71 is coaxial with the inner chamber 400 along its longitudinal axis Y - Y and thus coaxial with the rod 6. At least at the end portion 71A near the valve body 2, the receiving chamber 71 is closed by a receiving plate 710. The receiving chamber 71 is filled with a solid thermal insulation material, such as epoxy fiberglass (vetronite) of grade G10 - FR4. The thermal insulation material preferably forms a solid body made of one piece or several pieces.

[0104] Preferably, the receiving chamber 71 is fixed to the rod 6 such that the receiving chamber 71 can be inserted into the inner chamber 400 together with the rod 6, which greatly facilitates the assembly and / or maintenance operations of the valve 1'. In fact, also in the case of the extended configuration and thus in the presence of the thermal insulation assembly 7, the closing member 3 and the sealing assembly 60 can be withdrawn / inserted in a particularly easy and quick manner, that is, by operating only at the top inlet opening 50 of the valve 1' without the need to directly reach the inner cavity 20 of the valve body 2.

[0105] Figure 14 is shown Figures 1 to 12 An alternative embodiment (designated by the reference numeral 1") of the embodiment shown, which differs only in that the valve body 2 has a different structure. The valve body 2 has a generally T - shaped configuration such that the fluid inlet port 211 has an axis X1 that is substantially orthogonal to the axis X of the fluid outlet port 212 and substantially parallel to or coincides with the axis Y of the rod 6 and the closing member 3. For the rest, the solutions regarding the structure of the sealing assembly 60 and the closing member 3 and the cage - like body 40 are substantially the same as the above - mentioned solutions.

[0106] Figure 15 Another embodiment (designated by 1''') of the valve according to the present invention is involved. In this case, the valve is configured as a on - off valve. The structure of this valve corresponds to Figure 14 the structure of the control valve, and differs from Figure 14 the structure of the control valve only in the different configuration of the opening 46 of the cage - like body.

[0107] It can be clearly seen from the above how the present invention achieves the set goals and objectives. In particular, the present invention provides a pressure balance valve that can be used both as a control valve and as a shut-off valve, and whose sealing system has a longer service life compared to the sealing systems of prior art solutions. The longer service life stems from the fact that when the valve is closed, the sealing element is energized, while during valve regulation (when the closing member is vibrated relative to the cage body), the sealing element remains non-energized. Advantageously, the sealing assembly provided by the present invention is easy to manufacture and assemble because it can be inserted (and subsequently removed) together with the closing member by means of a rod connected to the closing member.

Claims

1. A pressure balancing valve (1; 1', 1", 1"'), including: - a valve body (2), the valve body (2) comprising a fluid inlet port (211) and a fluid outlet port (212), wherein the valve body (2) defines an inner cavity (20) that allows the fluid inlet port (211) to communicate with the fluid outlet port (212), wherein the inner cavity (20) is accessible through a top access opening (213, 50) of the valve (1; 1'); - a removable cover (5) closing the top access opening (213, 50); a cage-like body (40) arranged in the inner cavity (20) and associated with the valve body (2) in a fixed position, wherein the cage-like body (40) defines a sliding seat (43) for a closing member (3), wherein the cage-like body (40) comprises at least one lateral opening (46) for a fluid flow; - a closing member (3) which is movable in the sliding seat (43) between a closed position in which the lateral opening (46) of the cage-like body (40) is closed and a fully open position in which the lateral opening (46) of the cage-like body (40) is fully free, wherein the closing member (3) comprises at least one pressure-balancing channel (51) extending between a first surface (311) of the closing member (3) and a second surface (312) of the closing member (3), wherein the channel (51) enables a first portion (21) of the inner cavity (20) defined between the fluid inlet port (211) and the first surface (311) of the closing member (3) to communicate with a second portion (22) of the inner cavity (20) defined between the cover (5) and the second surface (312) of the closing member (3); a rod (6) comprising a first end (61) connected to the closing member (3) at the second surface (312) and a second end (62) connected to an actuating device (600) of the valve (1, 1'), wherein the rod (6) extends through the second portion (22) of the inner cavity (20); a sealing assembly (60) providing a fluid seal between the second portion (22) of the inner cavity (20) and a third portion (23) of the inner cavity (20) communicating with the outlet port (212), Wherein, the sealing assembly (60) comprises: - at least one sealing ring (61, 62, 63, 64), the sealing ring (61, 62, 63, 64) are arranged around the first cylindrical portion (331) of the closing member (3) and contact the first cylindrical portion (431) of the sliding seat (43) of the cage body (40), wherein the first cylindrical portion (431) of the sliding seat (43) is axially delimited by a first abutment surface (66A), and wherein the first cylindrical portion (331) of the closing member (3) is axially delimited by a second abutment surface (66B); at least one annular thrust flange (68) arranged in the second portion (22) of the inner cavity (20) in a position adjacent to the second surface (312) of the closing member (3), wherein the annular thrust flange (68) comprising an annular edge (69) in contact with a first surface of said at least one sealing ring (61, 62, 63, 64), and wherein said thrust annular flange (68) floats axially relative to said closure member (3); - elastic means (65) which push the thrust annular flange (68) towards the second surface (312), And wherein the abutment surfaces (66A, 66B) are defined so that when the closing member (3) moves toward the closed position, the at least one sealing ring (61, 62, 63, 64) abuts against the first abutment surface (66B) at the side opposite to the side contacting the annular edge (69) before the closing member (3) reaches the closed position.

2. The valve (1; 1', 1", 1'") according to claim 1, wherein: The sealing assembly (60) includes a plurality of sealing rings (61, 62, 63, 64) arranged in a packaging configuration, wherein the sealing ring (61) abuts against the first abutment surface (66A) when the closing member (3) moves toward the closed position and before the closing member (3) reaches the closed position, and wherein another sealing ring (64) contacts the annular edge (69) of the thrust flange (68).

3. The valve (1; 1', 1", 1'") according to claim 1, wherein: The sealing assembly (60) includes a plurality of sealing rings (61, 62, 63, 64) arranged in a packed configuration, wherein a first outer sealing ring (61) contacts the first abutment surface (66A) or the second abutment surface (66B), and a second outer sealing ring (64) is contacted by the annular edge (69) of the thrust flange (68), and the plurality of sealing rings (61, 62, 63, 64) include at least one central sealing ring (62, 63) in contact with the first outer sealing ring (61) and the second outer sealing ring (64).

4. The valve (1; 1', 1", 1'") according to claim 3, wherein: The plurality of sealing rings include two central sealing rings (62, 63) in contact with each other, wherein each central sealing ring (62, 63) contacts one of the outer sealing rings (61, 64).

5. The valve (1; 1', 1", 1'") according to any one of claims 2 to 4, wherein: The sealing rings (61, 62, 63, 64) have a substantially trapezoidal cross section, wherein the cross section is evaluated in a radial section plane.

6. The valve (1; 1', 1", 1'") according to any one of claims 1 to 5, wherein: The thrust flange (68) includes a planar portion (68A) having an annular shape, and the annular edge (69) protrudes from an end of the planar portion (68A) in a direction substantially perpendicular to a reference plane in which the planar portion (68A) extends.

7. The valve (1; 1', 1", 1'") according to any one of claims 1 to 6, wherein: The thrust flange (68) is connected to the closing member (3) in an axially floating manner by means of a plurality of coupling pins (75) protruding from the second surface (312) of the closing member (3), wherein each coupling pin (75) extends through an opening (68B) formed in the planar portion (68A) of the thrust flange (68).

8. The valve (1; 1', 1", 1'") according to claim 7, wherein: The elastic device (65) includes a plurality of springs, each of which is arranged around one of the connecting pins (75) so as to be axially inserted between the thrust flange (68) and a stop device (78) fixed to the connecting pin (75), wherein the thrust flange (68) is located between the spring and the second surface (312) of the closing member (3).

9. The valve (1; 1', 1", 1'") according to claim 8, wherein: The stop means (78) comprises at least one nut (78A) screwed onto the free end (75A) of the corresponding coupling pin (75).

10. The valve (1; 1', 1", 1'") according to any one of claims 1 to 9, wherein: The closing member (3) includes a second cylindrical portion (332) having a diameter (D1) larger than the diameter (D2) of the first cylindrical portion (331), and wherein the sliding seat (43) of the cage-shaped body (40) includes a second cylindrical portion (432) having a diameter (D1*) smaller than the diameter (D2*) of the first cylindrical portion (431) of the sliding seat (43), and wherein the second cylindrical portion (332) of the closing member (3) contacts the second cylindrical portion (432) of the sliding seat (43).

11. The valve (1') according to any one of claims 1 to 10, wherein: The valve comprises a valve body extension (4) connected to the valve body (2) at the top access opening (213), wherein the valve body extension (4) defines an access opening (50) of the valve (1'), wherein the access opening (50) is closed by the cover (5), wherein the valve body extension (4) is penetrated by the rod (6) and defines an inner chamber (400) having an annular shape, wherein a thermal insulation assembly (7) is removably received in the inner chamber (400).

12. The valve (1; 1', 1", 1'") according to any one of claims 1 to 11, wherein: The at least one sealing ring (61, 62, 63, 64) has no energizing elastic insert.

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