Valve comprising a tiltable piston part

Abstract

The present invention relates to a valve (1), for example a stop valve. The valve (1) comprises a housing having a first port (3) and a second port (4). Further, the valve (1) comprises a valve rod (6) arranged inside said housing as well as a first piston part (9) extending along a first longitudinal axis (Lp1) and coupled to the valve rod (6).The valve rod (6) is rotationally moveable about its longitudinal axis (Lv) and the first piston part (9) is axially moveable along the first longitudinal axis (Lp1). In order to provide a valve (1) that compensates misalignments of valve components and ensures a leakage-free valve closure, the valve (1) additionally comprises a second piston part (10) which extends along a second longitudinal axis (Lp2), and which is axially coupled to the first piston part (9). The second piston part (10) is moveable together with the first piston part (9) between an open position and a closed position. Further, the second piston part (10) is tiltable with respect to the first piston part (9).

Description

[0001] Valve comprising a tiltable piston part

[0002] The present invention relates to a valve, for example a stop valve, comprising a housing with a first port and a second port, a valve rod as well as a first piston part and a second piston part.

[0003] Valves and especially stop valves have long been known and used as such typically to shut off or control the flow of fluids. Nevertheless, demanding environments require constant improvements of known valve systems. Such environments may occur in CO2-refrigeration systems, wherein for example temperatures of 150°C and pressures of 140 bar are reached, so that large torques of for example 70 Nm are required to provide for a reliable valve closure.

[0004] Typically, each valve comprises of several component parts, which are individually manufactured and assembled. This, however, means that due to assembly and manufacturing, the final valve assembly is within a tolerance range and misalignments between a valve closure element comprising a sealing element and a valve seat onto which the valve closure element is to be seated in order to close the valve may have to be compensated. Therefore, often a safe and reliable valve closure, which is preferably leakage-free, may only be guaranteed when these differences in tolerance are compensated for, for example by applying large torques and pressing the valve closure element against the valve seat. When the valve closure element is pressed against the valve seat, deformation of the sealing element ensures a tight seal despite the misalignment.

[0005] However, regardless of whether the valve is closed manually or automatically, the application of large torques has several disadvantages. For example, in the case of a valve system controlled by an electro motor, the motor must be able to apply larger torques onto the valve closure element which is typically reflected in the costs as well as the size of the electro motor. It is therefore an object of the present invention to provide a valve that eliminates these disadvantages and that guarantees reliable valve closure and compensation of misalignments even with significantly lower torques than a comparable system valve system.

[0006] The object is solved by a valve according to claim 1 .

[0007] The valve, for example a stop valve, comprises a housing having a first port and a second port. One port may be an inlet port, wherein the other port may be an outlet port. Thus, when the valve is in an open position fluid may flow from the inlet port to the outlet port, for example from the first port to the second port. A valve rod is arranged inside said housing. Further, a first piston part extending along a first longitudinal axis is coupled to the valve rod. The valve rod is rotation- ally moveable about its longitudinal axis, i.e. the longitudinal axis of the valve rod. The valve rod may be axially constrained to the housing and therefore not axially moveable along its longitudinal axis. When the valve component parts are assembled, the valve rod's longitudinal axis and the first longitudinal axis of the first piston part run in parallel and are not congruent. However, preferably the valve's longitudinal axis and the first longitudinal axis are aligned. The valve rod may thus also be rotated about the first longitudinal axis and relative to the housing.

[0008] Upon rotation of the valve rod, which may be caused by applying torque manually, e.g. by a human, or automatically, e.g. by a motor such as an electro motor, to the valve rod, the first piston part is axially moved along the first longitudinal axis, and with respect to the housing. In this regard, the first piston part or a further component part coupled to the first piston part may be threadedly engaged with the valve rod and rotationally constrained to the housing in order to axially move along the first longitudinal axis upon rotation of the valve rod. For example, a lead nut as well as a washer may be provided, wherein the lead nut as part of a first piston part is threadedly engaged to the valve rod, rotationally constrained to the housing and configured to convert a rotational movement of the valve rod into an axial movement of the first piston part along a first longitudinal axis by means of the washer which has a protruding key guided in a key way of the housing. The threaded engagement between the lead nut and the valve rod may be self-locking. Although the valve rod may be rotated automatically, for example by an electro motor, the valve rod may also be configured to be rotated manually, for example when the electro motor is broken.

[0009] Further, the valve comprises a second piston part which extends along its longitudinal axis, i.e. along a second longitudinal axis. The second piston part is axially coupled to the first piston part and therefore moveable together with the first piston part between an open position and a closed position of the valve. This means that when the valve rod is rotated in order to axially move the first piston part, the second piston part is also translated and configured to close one of the ports in order to prevent fluid flow from one port to the other. Thus, when the first piston part is moved in a valve closing direction from the open position in the closed position, the second piston part is also axially moved, wherein, in the closed position, the second piston part is seated on a valve seat in order to close the valve. Accordingly, the second piston part may comprise a seal, which when the second piston part is in the closed position, may be seated on the valve seat.

[0010] In addition, the second piston part is tiltable with respect to the first piston part. This may mean that the second piston part may be deflected with respect to the first piston part in a tilting direction. Consequently, the second longitudinal axis, which may be aligned with the first longitudinal axis when the valve is in the open position, may be tilted with respect to the first longitudinal axis when the valve is in the closed position. The second longitudinal axis may further be aligned with the longitudinal axis of the valve rod, for example when the valve is in the open position. However, the second piston part may be tilted with respect to the first piston part when the valve is in the closed position and consequently the second longitudinal axis may be tilted with respect to the first longitudinal axis as well as the longitudinal axis of the valve rod in the closed state.

[0011] In other words and considering a plane of the second piston part with a normal vector defining a normal direction of the plane, wherein the normal vector runs parallel to the second longitudinal axis, tilting the second piston part with respect to the first piston part results in the plane being slanted with respect to the first longitudinal axis, i.e. an angle not equal to 0° is formed between the normal vector and the first longitudinal axis. Thus, the term "tilting", "tiltable" or "tilted" may define the deflection of one axis, here the second longitudinal axis, with respect to another axis, here the first longitudinal axis, wherein both axes, if not tilted, are parallel or aligned to each other, and wherein the tilting of the axis, here the second longitudinal axis, is related to the deflection of the corresponding component, here the second piston part. Tilting of the second piston part allows to compensate for tolerances and misalignments in the valve due to manufacturing. Therefore, forces required to securely close one of the ports are significantly reduced.

[0012] According to one aspect, the second piston part may be tiltable with respect to the first piston part by a tilting-angle defined between the first longitudinal axis and the second longitudinal axis. The tilting angle between the first longitudinal axis and the second longitudinal axis may be at least at least 0.2°. However, in some embodiments a tilting angle of at least 0.5° may be preferred. But typically tilting angles greater than 1 ° are not required to produce the desired technical effect. Nevertheless, the value of 5° should be understood less as a limiting upper limit value and more as an indication for the skilled person. Further, the tilting angle may also be between 0.2° and 5°. Choosing a tilting angle that is very large may cause the second piston part to bump against the housing, when the fluid flow may deflect the second piston part, which may lead to undesirable effects and may cause damage. At the same time, choosing a tilting angle that is too small may not compensate sufficiently for manufacturing tolerances and misalignments.

[0013] According to a further aspect of the invention, the first piston part and the second piston part may be partially arranged inside one another. Therefore, a portion of one of the first piston part and the second piston part comprising a plug section having an outer, first diameter is arranged inside a socket section of the other one of the first piston part and the second piston part. Hence, either the first piston part or the second piston part may comprise the plug section. The other part then comprises the socket section. Therefore, either the first piston part may be partially arranged inside the second piston part or vice versa. The plug section and the socket section define portions of the respective piston parts in which the piston parts overlap. Further, the socket section may comprise an inner, second diameter being larger than the first diameter in order to receive the plug section of the respective piston part. Furthermore, there may be a gap formed by a lateral distance in between the plug section and the socket section. Providing a gap in between the plug section and the socket section allows for the tilting of the second piston part. However, other types of connection between the two piston parts are also possible. For example, a joint could be used in order to tilt the second piston part with respect to the first piston part. Using a plug-socket-connection, however, allows a simple, uncomplex and low-wear assembly.

[0014] According to another aspect, the first piston part may be partially arranged inside the second piston part. The outer, first diameter of the plug section and the inner, second diameter of the socket section may differ from one another in a range from 0.2 mm to 0.6 mm. Considering a cylindrical socket section into which a cylindrical plug section is inserted, this would result in a circumferential gap between corresponding inner and outer walls of the two sections of between 0.1 mm and 0.3 mm, if the cylindrical sections are arranged centered with respect to one another. Preferably the first diameter of the plug section and the second diameter of the socket section differ from one another by 0.4 mm. Obviously when one section is laterally shifted with respect to the other section, there may be no gap on one side but the gap on the other side is increased. The outer, first diameter is to be understood according to the invention as the maximum diameter of the plug section. Therefore, when the plug section comprises recesses, the outer, first diameter is decreased in the area of the recesses. Consequently, the diameter in the area of the recesses is not counted towards the outer, first diameter. In contrast, and according to the invention, the inner, second diameter is to be understood as the minimum diameter of the socket section. Therefore, when the socket section comprises recesses, the inner, second diameter is increased in the area of the recesses. Consequently, the diameter in the area of the recesses is not counted towards the inner, second diameter. In summary, this means that when the outer, first diameter of the plug section may be 15.6 mm at some points of the overlapping area, and 15 mm as well as 14 mm at others points of the overlapping area, the outer, first diameter is understood to be 15.6 mm. In contrast, when the inner, second diameter of the socket section may be 16 mm at some points of the overlapping area, and 17.6 mm as well as 18 mm at others points of the overlapping area, the inner, second diameter is understood to be 16 mm. Here, the socket section and the plug section are inserted into each other along the second longitudinal axis by between 20 mm and 22 mm, i.e. there is an overlapping area area between the plug section and the socket section of 20 mm to 22 mm measured along the second longitudinal axis.

[0015] In one example, the outer, first diameter of the plug section may be, for example, 11.5 mm at some points of the overlapping area, and 11 mm as well as 10.5 mm at others points of the overlapping area, the outer, first diameter would be understood to be 11 .5 mm. The inner, second diameter of the socket section may then be between 11 .7 mm and 12.1 mm. In one embodiment, the second piston part may be axially coupled to the first piston part by a bearing arranged between the socket section and the plug section. Hence, the bearing may be arranged in the overlapping area of the socket section and the plug section. The bearing may be a rolling bearing, preferably a ball bearing. However, any other bearing configured to axially couple the second piston part to the first piston part may be used. The ball bearing may comprise thirteen balls. The balls of the ball bearing may be made of stainless steel, wherein the first piston part and the second piston part are made of low-carbon steel. The bearing may be arranged in respective recesses formed on the first diameter and the second diameter. The bearing allows for a relative rotational movement between the first piston part and the second piston part. However, due to the bearing, the second piston part may not be axially moved with respect to the first piston part. In this regard, 'not be axially moved' may also be understood as only allowing limited axial movement, wherein the limited axial movement does not allow decoupling of the first piston part and the second piston part. At the same time, the bearing allows for a tilting between the second piston part and the first piston part. Using a ball bearing may be beneficial as the second piston part may roll on the surfaces of the rolling elements relative to the first piston part in order to be tilted. Further, ball bearings require little maintenance, which is an advantage due to the arrangement of the bearings between the socket section and the plug section.

[0016] According to one embodiment, a first seal may be provided between the socket section and the plug section. Hence, the seal may be arranged in the overlapping area of the socket section and the plug section. The first seal may contribute to impeding rotation between the second piston part and the first piston part due to friction. The first seal may seal the gap formed by the lateral distance. This means that no fluid may pass from one side of the seal within the gap or across the seal to the other side of the seal. In one embodiment, the first seal may be arranged further away from the valve rod than the bearing. In other words, the bearing may be closer to valve rod than the first seal. Considering a valve comprising a balancing pressure chamber as described below, the first seal may allow for the fluid and the pressure respectively to fully propagate to the balancing pressure chamber.

[0017] In one embodiment, the first seal may comprise a first sealing element comprising an O-ring and a second sealing element partially encircling the first sealing element. Further, the first sealing element may abut against the second sealing element. The O-ring may be an inner sealing element encircling the plug section about the first longitudinal axis, wherein the second sealing element may be an outer sealing element partially encircling the inner sealing element as well as the plug section about the first longitudinal axis. Thus, "partially" does not mean that the second sealing element is not fully encircling the plug section but may mean that the second sealing element is not fully encircling the first sealing element. The second sealing element may have a substantially semicircular cross-section, a curved contour of which abuts against the socket section. Using two different elements to provide the first seal allows the use of different materials for each respective element. In addition, the respective sealing allows tilting of the second piston part relative to the first piston part without reducing the sealing effect of the first seal. Further, the O-ring may press the second sealing element against the socket section. Especially when the valve is used under high pressures and temperatures of 140 bar and 150 °C, the gap would be too large to be reliably sealed only by means of an O-ring. The pressure difference over the closed valve may be over 90 bar.

[0018] According to a further embodiment, the valve may comprise, at an end of the second piston part facing away from the first piston part, a tapered portion. The tapered portion may comprise a central apex surrounded by a concavely shaped flow guiding surface converging towards the apex. The tapered portion may be screwed onto the second piston part. The specific shape of the tapered portion may improve fluid flow, with less force exerted by the fluid flow on the piston parts.

[0019] Further, the valve may additionally comprise a second seal configured to seal the first port with respect to the second port when the valve is in the closed position. The second seal may at least partially be arranged, for example clamped, between the second piston part and the tapered portion. Therefore, when the tapered portion is screwed onto the second piston part, the second seal may be held in position without the need for additionally fixing means. In the closed position of the valve, the second seal may be pressed against an orifice of one of the ports. Accordingly, when the second piston part is moved to the closed position, i.e. when the fluid flow from the first port to the second port is prevented, the second seal may be seated on the valve seat.

[0020] In one embodiment, the second seal may comprise polyether ether ketone (PEEK) and / or the first seal may comprise polytetrafluoroethylene (PTFE). For example, the first sealing element of the first seal may be made of elastic material, such as rubber, wherein the second sealing element may be made of PTFE. Consequently, the O-ring made of rubber may exert a force onto the second sealing element, wherein the second sealing element is pressed against the socket section of the second piston part. The use of PTFE for the second sealing element allows for less deformation under high pressure. At the same time the O-ring made of rubber helps to seal the gap. Further, the use of PEEK for the second seal may provide a seal which comprises high strength, high stiffness and which is temperature resistant. In one embodiment, also the second seal may comprise two sealing elements, for example, an O-ring made of rubber which may exert a force onto a further sealing element made of PEEK.

[0021] In one embodiment, when the second piston part is tilted with respect to the first longitudinal axis, the second piston part may be moved partially in a tilting- direction. Every direction perpendicular to the first longitudinal axis may be allowed to be the ti Iting-di rection. During tilting, the second piston part does not only move lateral in the tilting-direction but also partially in a direction parallel to the first longitudinal axis, for example in the direction towards the valve rod. However, especially when the socket section and the plug section are cylindrically shaped, the tilting-direction may be any direction perpendicular to the first longitudinal axis. Consequently, considering the plug section of the first piston part, which may be cylindrical in shape and thus may have a circular cross-section, a tilting of the second piston part in which the second piston part partially moves in a direction lateral to the first longitudinal axis, and in which this lateral direction may be any direction relative to the cross-sectional area, i.e. each direction with respect to the 360° of the circular cross-sectional area, would be a possible tilting-direction. This degree of freedom allows extremely effective compensation of differences in tolerances and misalignments.

[0022] In a further embodiment, the valve may comprise a balancing pressure chamber and an inner channel. When the valve is in the closed position, the inner channel may be configured to fluidically connect the first port with the balancing pressure chamber. Therefore, when the valve is in the closed position and the second seal seals the first port with respect to the second port, the fluid for example pressing against the tapered portion may enter the inner channel in order to flow into the balancing pressure chamber. The balancing pressure chamber may be sealed with respect to the ports, for example by a piston seal as part of the first piston part abutting against the housing independent of the position of the first piston part. Further, the balancing pressure chamber is provided so that fluid entering the balancing pressure chamber may apply a force onto a portion of the piston parts, i.e. in the valve closing direction. Due to this force, directed in the valve closing direction, the fluid acting for example on the tapered portion and applying a force in the valve opening direction may be balanced, i.e. substantially identical in magnitude but opposite in direction. The forces caused by the fluid pressure applied to the pressure surfaces are more similar the more similar the surfaces are on which the pressures act. Ideally, the pressure surfaces are identical in size and orientation, so that the forces caused by a fluid pressure acting on the surfaces and pointing in the valve opening direction or the valve closing direction are completely balanced. Consequently, less force is required to hold the valve in the closed position. In this regard, the valve may comprise the balancing chamber, wherein the balancing pressure chamber may comprise a first pressure surface at least partially facing in the valve opening direction, wherein the second piston part may comprise a second pressure surface at least partially facing in the valve closing direction, and wherein the first pressure surface and the second pressure surface may be configured so that, when the valve is in the closed position, a first force acting on the first pressure surface and a second force acting on the second pressure surface may be substantially identical in magnitude but opposite in direction. Considering the first port as the inlet port, this balancing may be called the inlet balancing or balancing on the first port side.

[0023] However, the valve may also provide for an output balancing or a balancing on the second port side, i.e. a balancing with respect fluid which already passed the second piston part and which is about to exit the second port. In this regard, the valve may comprise a third pressure surface at least partially facing in the valve opening direction, and the first piston part may comprise a fourth pressure surface at least partially facing in the valve closing direction, and wherein the third pressure surface and the fourth pressure surface may be configured so that, when the valve is in the closed position, a third force acting on the third pressure surface and a fourth force acting on the fourth pressure surface may be substantially identical in magnitude but opposite in direction. Assuming that the first port balancing and the second port balancing are both applied, ideally all forces caused by the fluid balance each other out, so that the valve is held in position even without a continuous application of force in the valve closing direction or a locking mechanism. Nevertheless, the valve may additionally or alternatively comprise a locking mechanism that locks the valve in a desired position so that the valve is prevented from changing position without unlocking the locking mechanism.

[0024] In one aspect, the inner channel may comprise an opening at least partially facing in the valve closing direction. Considering the opening as a plane comprising a normal vector, this vector at least partially points towards the valve closing direction or in other words, the normal vector of the opening plane comprises one part which is parallel with respect to the valve closing direction. Additionally, in one embodiment, the opening may also face the first port. Further, the inner channel may be at least partially arranged inside the first piston part, the second piston part as well as the tapered portion, if present. Therefore, the inner channel provides for a fluid passage from the first port side of the valve through the aforementioned components of the valve and leads in a region at least partially above the first piston part and the second piston part. Hereby, it is guaranteed that the fluid can flow into an area of the valve where the fluid may exert the first force on the first pressure surface. In one embodiment, the inner channel may also at least partially be arranged inside the valve rod.

[0025] In one embodiment, the second piston part may comprise, at the end of the second piston part facing away from the first piston part, an annular channel arranged in a plane perpendicular to the second longitudinal axis. Therefore, the annular channel may be arranged so that the second longitudinal axis is encircled by the annular cannel. Further, the tapered portion may be arranged at the end of the second piston part facing away from the first piston part. The annular channel may open towards the valve closing direction such that a portion of the inner channel of the tapered portion may always be fluidically connected to the remaining portions of the inner channel via the annular channel regardless of a rotational position of the tapered portion with respect to the second longitudinal axis. Hence, when the tapered portion is for example screwed onto the second piston part, it does not matter how far or how tightly the tapered portion is screwed on the first piston part, or how the tapered portion is brought up to the second piston part during assembly to ensure that the inner channel fluidically connects the first port with the balancing pressure chamber. Therefore, providing an annular channel simplifies the assembly of the valve and allows the fluid to propagate to the balancing pressure chamber independent of the rotational position of the tapered portion.

[0026] According to a further aspect, the valve may comprise an electro motor. Hence, the valve may be automatically driven by the electro motor, wherein the electro motor applies a torque to the valve rod. The electro motor may be a DC-electro motor. The electro motor may be configured to apply a maximum torque of less than 30 Nm on the valve rod. Preferably the electro motor applies a torque of less than 20 Nm. The electro motor may apply a torque of in between 8 N m and 12 Nm. The use of such a small electro motor has been tested successfully for configurations in which due to a misalignment a torque of about 70 Nm was previously required in order to securely close the valve, i.e. in order for the valve to be leak- free. The electro motor may be equipped with a control unit that allows remote access to the valve control, for example via a network. The valve may also be equipped with other components, such as sensors, a data storage and / or a transmitting and receiving unit, to send data to and receive data from a remote control unit.

[0027] Finally, it should be noted that the dependent on the combination of features, the invention also provides for a valve which may be driven by an electric motor, comprising a tiltable piston part, and wherein the valve is balanced.

[0028] Additional features, advantages and possible applications of the invention result from the following description of exemplary embodiments and the drawings. All the features described and / or illustrated graphically here form the subject matter of the invention, either alone or in any desired combination, regardless of how they are combined in the claims or in their references back to preceding claims.

[0029] Preferred embodiments of the invention will now be described with reference to the drawings, in which:

[0030] Fig. 1 shows a cross-sectional view of a valve according to the invention in an open position;

[0031] Fig. 2 shows a detailed view of section A in Fig. 2;

[0032] Fig. 3 shows a cross-sectional view the valve according to Fig. 1 in a closed position;

[0033] Fig. 4 shows a cross-sectional view of the valve according to Fig. 1 , wherein a second piston part is tilted with respect to a first piston part;

[0034] Fig. 5 shows a detailed view of section B in Fig. 4;

[0035] Fig. 6 shows a detailed view of section C in Fig. 4;

[0036] Fig. 7 shows a sectional view along line D-D in Fig. 4; and

[0037] Fig. 8 shows a detailed view of section E in Fig. 4.

[0038] In Fig. 1 a valve 1 according to the invention is depicted in an open position. The valve 1 comprises a housing 2 with a first port 3 and a second port 4, wherein the first port 3 comprises a valve seat 3a. Further, the first port 3 may define a fluid inlet and the second port 4 may define a fluid outlet. In the open position a fluid may flow into the first port 3 and out of the second port 4. The housing 2 comprises a top part 2a and a lower part 2b. The top part 2a may also be called bonnet. The top part 2a may substantially accommodate actuation means of the valve 1 , wherein the lower part 2b may comprise the ports 3, 4.

[0039] The top part 2a and the lower part 2b of the housing 2 of the valve 1 are screwed together by bolts 5. During assembly of the valve components, these bolts 5 and other manufacturing tolerances of the valve components, among others, would normally, i.e. without the inventive concept, cause tolerances and misalignments that impair the ability of the valve to prevent fluid flow between the first port 3 and the second port 4 once being moved into a closed position as depicted in Fig. 3. Therefore, it is the object of the present invention to counteract these tolerances and misalignments and to improve the valve.

[0040] In this regard, the valve 1 comprises actuation means such as a valve rod 6 arranged inside the housing 2. Here, the valve rod 6 is functionally coupled to an electro motor 7. The electro motor 7 may be a DC-electro motor. Further the electro motor 7 may be configured to apply a torque of less than 30 Nm to the valve rod 6, thereby rotating the valve rod 6 about the longitudinal axis Lv of the valve rod 6. The electro motor 7 may be remotely controlled. However, instead of the use of the electro motor 7, the valve 1 may be operated manually, for example by a human using a hand wheel.

[0041] Further, a lead nut 8 as part of a first piston part 9 is threadedly engaged to the valve rod 6, rotationally constrained to the housing 2 and configured to convert a rotational movement of the valve rod 6 into an axial movement of the first piston part 9 along a first longitudinal axis Lpi. Here, the first longitudinal axis Lpiand the longitudinal axis Lvof the valve rod 6 are aligned. The threaded engagement between the lead nut 8 and the valve rod 6 may be self-locking. In Fig. 1 , the first piston part 9 is arranged above a second piston part 10, at least in some areas as the first piston part 9 comprises a plug section 11 , which is inserted into a socket section 12 of the second piston part 10. The plug section 11 and the socket section 12, i.e. the first piston part 9 and the second piston part 10, are axially coupled by a bearing 13. Here, the bearing 13 is provided by a ball bearing with balls made of stainless steel. The bearing 13 allows the second piston part 10 to rotate relative to the first piston part 9.

[0042] A more detailed view of section A of Fig. 1 is shown in Fig. 2. Section A depicts clearly that the balls are arranged in recesses of the plug section 11 and the socket section 12. The rolling elements of the bearing 13 are accessible via a grub screw 14, which simplifies assembly of the valve 1 , for example.

[0043] Further, Fig. 2 shows that an outer diameter Doof the plug section 11 of the first piston part 9 is smaller than an inner diameter Di of the socket section 12 of the second piston part 10. Therefore, a gap 18 is formed in between the plug section 11 and the socket section 12.

[0044] Furthermore, a first seal 15 is arranged in a recess of the plug section 11 of the first piston part 9. The first seal 15 is formed by two sealing elements, namely a first sealing element 16 and a second sealing element 17. The first sealing element 16 is formed by an O-ring which is encircled by a second sealing element 17 with a substantially semicircular cross-sectional profile. The first sealing element 16 is arranged at least partially within the second sealing element 17. The O-ring presses the second sealing element 17 against the socket section 12 and is therefore configured to seal the gap 18 formed by a lateral clearance between the plug section 11 and the socket section 12. The gap 18 may be better seen in Fig. 6. Due to the tilting, a gap angle [3 is formed between an outer wall of the plug section 11 and an inner wall of the socket section 12. Due to the abutment and the friction created between the first seal 15 and the socket section 12, rotation of the second piston part 10 relative to the first piston part 9 is made more difficult, i.e. rotation is possible in principle, but only by applying a very large amount of force.

[0045] The gap 18 between the first piston part 9 and the second piston part 10 allows the second piston part 10 to be tiltable relative to the first piston part 9. In the valve position shown in Fig. 1 , however, the second piston part 10 is not tilted so that a second longitudinal axis LP2 of the second piston part 10 is not deflected relative to the first longitudinal axis Lpiof the first piston part 9. Nevertheless, the second piston part 10 could be tilted in any direction perpendicular to the first longitudinal axis Lpi, wherein an arrow with a dashed line illustrates a possible tilting-direction Td, which is perpendicular to the first longitudinal axis Lpi.

[0046] In addition, the end of the second piston part 10 that points in the direction of the first port 3 comprises a tapered portion 19 that is screwed onto a pin 20 of the second piston part 10. A second seal 21 is arranged or clamped at least in part between the tapered portion 19 and the second piston part 9. When the valve 1 is moved into the closed position, as shown in Fig. 3, the second seal 21 is responsible for sealing the first port 3 and therefore pressed against the valve seat 3a.

[0047] The tapered portion 19 comprises a central apex 22 surrounded by a concavely shaped flow guiding surface 23. The flow guiding surface 23 converges from an outer area, in which the second seal 21 is arranged, to the apex 22. The flow guiding surface 23 serves in particular to guide the fluid flow and, for example, to prevent turbulence of the fluid at sharp edges of the valve parts.

[0048] In the tapered portion 19 shown here, an opening 24 is arranged that allows fluid to enter an inner channel 25. The inner channel 25 leads through the tapered portion 19, an annular channel 26, the second piston part 10 and the first piston part 9 towards a balancing pressure chamber 27. Here the balancing pressure chamber 27 is formed by several chambers, which are arranged at least in some areas above the first piston part 9 and the second piston part 10. The annular channel 26 is provided by a groove running around the second longitudinal axis LP2 of the second piston part 10. Therefore, the annular channel 26 allows fluid entry via the opening 24 and into the inner channel 25 of the second piston part 10 independently of the rotational position of the tapered portion 19 relative to the second piston part 10.

[0049] The first seal 15 seals the inner channel 25 so that fluid that has entered the inner channel 25 cannot leave the inner channel 25 via the gap 18. At the same time, a piston seal 28 is arranged between the inner wall of the housing 2 and the first piston part 9. The piston seal 28 is in contact with the housing 2. As can be seen in the comparison between Fig. 1 and 3, the piston seal 28 slides along the inner wall when the valve 1 moves from an open position (Fig. 1 ) to a closed position (Fig. 3). Consequently, piston seal 28 continuously seals the balancing pressure chamber 27 and allows fluid to enter or exit the balancing pressure chamber 27 only through the inner channel 25.

[0050] The fluid which flows into the balancing pressure chamber 27, especially in the closed position of the valve 1 shown in Fig. 3, exerts a force F1 here, which is shown by an arrow, and which presses on a first pressure surface 29, i.e. exerts a force in the valve closing direction. At the same time, the fluid in the area of the first port 3 presses against the tapered portion 19 and the second seal 21 , i.e. against a second pressure surface 30, wherein a force F2 opposite to the force F1 is exerted, i.e. a force pointing in the valve opening direction. Ideally, the pressure surfaces are designed in such a way that the forces balance each other out so that the valve 1 is considered balanced with respect to the first port 3 side. Further, the valve 1 comprises a third pressure surface 31 formed by a surface of the second piston part 10 facing at least partially in the valve opening direction. Furthermore, the valve 1 has a fourth pressure surface 32 which is formed by a surface of the first piston part 9 and which faces in the valve closing direction. The fluid, which is on the side of the outlet port, i.e. the second port 4, and which presses against the third and fourth pressure surfaces 31 and 32, also generates here ideally equal and opposite forces F3 and F4, which are also shown by arrows. Again, the balancing of forces ensures that the valve 1 is considered balanced with respect to the second port 4 side. Ideally, the forces F1 , F2, F3 and F4 balance each other out so that the valve 1 remains closed without any further force being applied in the valve closing direction and is considered balanced. Additionally, the self-locking threaded engagement between the lead nut 8 and the valve rod 6 may be configured to provide a biasing force in order to keep the valve closed. Nevertheless, the valve 1 may comprise a locking mechanism (not shown).

[0051] For reasons of clarity and comprehensibility, the forces F1 , F2, F3 and F4 and the pressure surfaces 29, 30, 31 and 32 are only schematically shown in Fig. 3. The pressure surfaces 29, 30, 31 , 32 do not have to be continuous surfaces in the sense of the invention. For example, the balancing pressure chamber 27, as shown here, is formed by several chambers, so that the first pressure surface 29 is not formed by a continuous surface. A pressure surface may therefore be understood as any surface or section of a surface that exerts a force in the previously described directions on the movable components of the valve 1 due to fluid pressure.

[0052] As can be seen in Fig. 3, the axes Lpi, LP2 and Lvare aligned. Here, this could be due to the fact that the tolerances are already compensated for by the manufacture and assembly of the valve 1 and no tilting of the second piston part 10 is necessary in order to properly close the valve 1. Nevertheless, also in Fig. 1 to 3 the second piston part 10 is tiltable with respect to the first piston part 9. Compared to the open valve position shown in Fig. 1 , the valve 1 in Fig. 3 is merely moved to the closed position.

[0053] In Fig. 4, the valve 1 illustrated in Fig. 1 is shown with a tilted second piston part 10. The tilting of the second piston part 10 with respect to the first piston part 9 may be understood here purely for illustrative purposes, because typically the tilting of the second piston part 10 only occurs when the second seal 21 comes into contact with the first port 3, i.e. the valve seat 3a, or else the tilting may be understood here as the effect of a flow that deflects the second piston part 10, even though the valve 1 is in the open position.

[0054] Thus, in Fig. 4, the second piston part 10 is tilted with respect to the first piston part 9. This means that the second piston part 10 is deflected by a tilting angle a. More precisely, the tilting angle a is formed between the first longitudinal axis Lpiand the second longitudinal axis LP2. The angle a is typically between 0.2° and 5°.

[0055] The section B depicted in Fig. 4 is shown in more detail in Fig. 5. Due to the deflection of the second piston part 10 with respect to the first piston part 9, it can be noticed that the gap 18 in Fig. 5 is larger in the upper left area, i.e. further away from the bearing 13, than in the lower left area, i.e. closer to the bearing 13. Due to the abutment of the plug section 11 against the socket section 12, however, the tilting is limited.

[0056] Furthermore, the structures of the second seal 21 and the piston seal 28 may also be identified very well in Fig. 5. Both seals 21 and 28 comprise two sealing elements, namely an O-ring and a further sealing element similar to the first seal 15. Preferably, the further sealing element is a stronger, less elastic material such as PEEK or PTFE, wherein the O-ring is made of a softer, more elastic material such as rubber. In the second seal 21 , the further sealing element, which will be in contact with the valve seat 3a, when the valve 1 is in the closed position, is made of PEEK. In the piston seal 28, the further sealing element, which is contact with the top part 2a of the housing 2, is made of PTFE. This makes the valve 1 particularly suitable for use at high pressures of over 90 bar.

[0057] Fig. 6 shows the section C from Fig. 5 in more detail, wherein section C is similar to section A depicted in Fig. 2 except for the fact that Fig. 6 shows a tilted state of the second piston part 10 and the respective effect on the gap 18.

[0058] Fig. 7 shows a sectional view along the line D-D shown in Fig. 4. The housing 2 and the first piston part 9 cover the first port 3, therefore only the second port 4 is visible in Fig. 7. In addition, the valve rod 6 is visible, which is surrounded by the lead nut 8. Furthermore, a washer 33 is shown, which has a protruding key 34 guided in a key way 35 of the housing 2, so that the rotational movement of the valve rod 6 can be converted into an axial movement of the first piston part 9.

[0059] Section E of Fig. 4 shown in Fig. 8 also shows a sectional view of the lead nut 8, the washer 33, the key 34 and the key way 35, but in a lateral sectional view. As pointed out above, the lead nut 8 may be in a self-locking threaded engagement with the valve rod 6. Further, the washer 33 may be slipped over the lead nut 8. The lead nut 8 may for example comprise a hexagonal shape as can be seen in Fig. 7. Therefore, relative rotation between the washer 33 and the lead nut 8 is prevented.

[0060] Furthermore, the first piston part 9 comprises a collar 9a that protrudes above and partially surrounds the washer 33. When the valve 1 is assembled, the collar 9a may be bent over the washer 33. Hereby, a biasing force acting on the washer 33 may be provided. The preload force exerted on the washer 33 and the shape of the washer 33 and the lead nut 8, which prevents rotation of the washer 33 relative to the lead nut 8, ensure a firm connection between the first piston part 9 and the lead nut 8, allowing forces and movements between the lead nut 8 and the first piston part 9 to be transferred.

[0061] When the electro motor 7 is operated and the valve rod 6 starts to rotate, the lead nut 8 comprising the washer 33 converts the rotational movement into an axial movement of the first piston part 9. The first piston part 9 may then, depending on the direction of rotation of the valve rod 6, move into the open position or the closed position. Considering a valve 1 in the open position, which allows fluid to pass from the first port 3 to the second port 4, rotational movement in the clockwise direction of the valve rod 6, may close the valve 1 in order to interrupt the fluid flow from the first port 3 to the second port 4. As soon as the second piston part 10 comprising the second seal 21 reaches the first port 3 and therefore starts to come into contact with the valve seat 3a, the tiltable second piston part 10 may be moved partially in the tilting-direction Td, perpendicular to the first longitudinal axis Lpi. When the second seal 21 , due to the misalignment of the valve parts, first comes into contact with one side of the valve seat 3a, for example, the right side of the valve seat 3a shown in Fig. 4, i.e. the side of the valve seat 3a closer to the second port 4, and the second piston part 10 is moved further in the valve closing direction, the second piston part 10 deflects relative to the first piston part 9 so that the tilting angle a is formed. Consequently, the second piston part 10 is tilted with respect to the first piston part 9. However, when the valve 1 is fully closed, the second seal 21 fully abuts the valve seat 3a. Speaking in terms of Fig. 4, the second seal 21 then also seats on the left side of the valve seat 3a, wherein the second piston part 10 is tilted. This tilting movement allows the second piston part 10 to compensate for deviations in tolerances and to compensate misalignments which occur during manufacturing and assembling of valve components. The tiltable second piston part 10 therefore allows for a secure closing of the valve 1 , i.e. a leakfree or leakage-free valve 1 . When the valve 1 is closed, the fluid may also pass through the opening 24 into the annular channel 26 as well as the inner channel 25 and into the balancing pressure chamber 27. Hereby, a force F1 is applied to the first pressure surface 29, which acts in the direction of the valve closing direction. Similarly, further forces F2, F3 and F4 act against components and pressure surfaces 30, 31 and 32 of the valve 1 . Preferably, the forces F1 and F2 are equal and act in opposite directions. The same applies to the forces F3 and F4. Therefore, these forces preferably balance each other out so that the valve 1 is balanced and remains in its closed position without further application of force. Subsequently, the fluid flow from the first port 3 to the second port 4 may remain blocked by the second piston part 10 until the electro motor 7 receives, for example, a signal from a control unit, which may form part of a network, wherein the signal causes the valve 1 to open again. This time, the valve rod 6 may then rotate in a counterclockwise direction, causing the first piston part 9 and the second piston part 10 axially coupled thereto to move in the valve opening direction.

[0062] Consequently, the present invention provides a valve 1 that can be closed particularly well due to its ability to tilt one piston part relative to another piston part and is therefore able to compensate for misalignments and tolerances.

[0063] List of reference signs

[0064] 1 Valve

[0065] 2 Housing

[0066] 2a Top part

[0067] 2b Lower part

[0068] 3 First Port

[0069] 3a Valve seat

[0070] 4 Second Port

[0071] 5 Bolt

[0072] 6 Valve rod

[0073] 7 Electro motor

[0074] 8 Lead nut

[0075] 9 First piston part

[0076] 9a Collar

[0077] 10 Second piston part

[0078] 11 Plug section

[0079] 12 Socket section

[0080] 13 Bearing

[0081] 14 Grub screw

[0082] 15 First seal

[0083] 16 First sealing element

[0084] 17 Second sealing element

[0085] 18 Gap

[0086] 19 Tapered portion

[0087] 20 Pin

[0088] 21 Second seal

[0089] 22 Apex

[0090] 23 Flow guiding surface

[0091] 24 Opening

[0092] 25 Inner channel 26 Annular channel

[0093] 27 Balancing pressure chamber

[0094] 28 Piston seal

[0095] 29 First pressure surface

[0096] 30 Second pressure surface

[0097] 31 Third pressure surface

[0098] 32 Fourth pressure surface

[0099] 33 Washer

[0100] 34 Key

[0101] 35 Key way

[0102] LvLongitudinal axis (valve rod)

[0103] LpiFirst longitudinal axis (first piston part)

[0104] LP2 Second longitudinal axis (second piston part) a Tilting angle

[0105] [3 Gap angle

[0106] Td Tilting-direction

[0107] Di Inner diameter

[0108] Do Outer diameter

[0109] F1 Force (acting on the first pressure surface)

[0110] F2 Force (acting on the second pressure surface)

[0111] F3 Force (acting on the third pressure surface)

[0112] F4 Force (acting on the fourth pressure surface)

Claims

Claims:1 . Valve (1 ), for example a stop valve, comprising a housing (2) having a first port (3) and a second port (4), a valve rod (6) arranged inside said housing (2), a first piston part (9) extending along a first longitudinal axis (Lpi) and coupled to the valve rod (6), wherein the valve rod (6) is rotationally moveable about its longitudinal axis (Lv), wherein the first piston part (9) is axially moveable along the first longitudinal axis (LPi), characterized in that the valve (1 ) comprises a second piston part (10) which extends along a second longitudinal axis (LP2), and which is axially coupled to the first piston part (9) and moveable together with the first piston part (9) between an open position and a closed position, wherein the second piston part (10) is tiltable with respect to the first piston part (9).

2. Valve (1 ) according to claim 1 , characterized in that the second piston part (10) is tiltable with respect to the first piston part (9) by a tilting-angle (a) defined between the first longitudinal axis (Lpi) and the second longitudinal axis (LP2), wherein the second piston part (10) is tiltable by at least 0.2°, preferably by at least 0.5°.

3. Valve (1 ) according to claim 1 or 2, characterized in that the first piston part (9) and the second piston part (10) are partially arranged inside one another, wherein a portion of one of the first piston part (9) and the second piston part (10) comprising a plug section (11 ) having an outer, first diameter (Do) is arranged inside a socket section (12) of the other one of the first piston part (9) and the second piston part (10), wherein the socket section (12) comprises an inner, second diameter (Di) being larger than the first diameter (Do), and wherein there is agap (18) formed by a lateral distance in between the plug section (11 ) and the socket section (12).

4. Valve (1 ) according to claim 3, characterized in that the first piston part (9) is partially arranged inside the second piston part (10), wherein the outer, first diameter (Do) of the plug section (11 ) and the inner, second diameter (Di) of the socket section (12) differ from one another in a range from 0.2 mm to 0.6 mm, preferably by 0.4 mm.

5. Valve (1 ) according to any one of claims 3 to 4, characterized in that the second piston part (10) is axially coupled to the first piston part (9) by a bearing (13) arranged between the socket section (12) and the plug section (11 ).

6. Valve (1 ) according to any one of claims 3 to 5, characterized in that a first seal (15) is provided between the socket section (12) and the plug section (11 ), wherein the first seal (15) seals the gap (18) formed by the lateral distance.

7. Valve (1 ) according to claim 6, characterize in that the first seal (15) comprises a first sealing element (16) comprising an O-ring and a second sealing element (17) partially encircling the first sealing element (16), wherein the first sealing element (16) abuts against the second sealing element (17).

8. Valve (1 ) according to any one of the preceding claims, characterized in that the valve (1 ) comprises, at an end of the second piston part (10) facing away from the first piston part (9), a tapered portion (19), wherein the tapered portion (19) comprises a central apex (22) surrounded by a concavely shaped flow guiding surface (23) converging towards the apex (22).

9. Valve (1 ) according to claim 8, characterized in that the valve (1 ) additionally comprises a second seal (21 ) configured to seal the first port (3) with respectto the second port (4) when the valve (1 ) is in the closed position, wherein the second seal (21 ) is at least partially arranged between the second piston part (10) and the tapered portion (19).

10. Valve (1 ) according to claim 6 to 9, characterized in that the second seal (21 ) comprises polyether ether ketone (PEEK) and / or the first seal (15) comprises polytetrafluoroethylene (PTFE), for example the first sealing element (16) is made of elastic material, such as rubber, and the second sealing element (17) is made of PTFE.

11. Valve (1 ) according to any one of the preceding claims, characterized in that, when the second piston part (10) is tilted with respect to the first longitudinal axis (Lpi), the second piston part (10) is moved partially in a tilting-direction (Td), wherein every direction perpendicular to the first longitudinal axis (Lpi) is allowed to be the tilting-direction (Td).

12. Valve (1 ) according to any one of the preceding claims, characterized in that the valve (1 ) comprises a balancing pressure chamber (27) and an inner channel (25), wherein, when the valve (1 ) is in the closed position, the inner channel (25) is configured to fluidically connect the first port (3) with the balancing pressure chamber (27).

13. Valve (1 ) according to claim 12, characterized in that the inner channel (25) comprises an opening (24) at least partially facing in the valve (1 ) closing direction, wherein the inner channel (25) is at least partially arranged inside the first piston part (9), the second piston part (10) as well as the tapered portion (19), if present.

14. Valve (1 ) according to claim 13, characterized in that the second piston part (10) comprises, at the end of the second piston part (10) facing away from thefirst piston part (9), an annular channel (26) arranged in a plane perpendicular to the second longitudinal axis (LP2), wherein the tapered portion (19) is arranged at the end of the second piston part (10) facing away from the first piston part (9), and wherein the annular channel (26) is open towards the valve (1 ) closing direc- tion such that a portion of the inner channel (25) of the tapered portion (19) is always fluidically connected to the remaining portions of the inner channel (25) via the annular channel (26) regardless of a rotational position of the tapered portion with respect to the second longitudinal axis (LP2).

15. Valve (1 ) according to any one of the preceding claims, characterized in that the valve (1 ) comprises an electro motor (7) configured to apply a maximum torque of less than 30 Nm on the valve rod (6).

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