VALVE UNIT

Description

[0001] The invention relates to a control valve unit according to the preamble of claim 1.

[0002] A control valve unit comprises a valve stem that is sealed against a valve housing by means of a sealing arrangement. The sealing arrangement comprises a sealing element in the form of a stuffing box, which contains a deformable packing material - also called packing - and a pressure sleeve that axially compresses the sealing element and onto which a contact force is exerted, in particular via a spring element. Depending on the operating conditions, e.g. high temperatures, high pressure and / or aggressive media, the packing can be made of different components and / or materials, for example aramid, graphite, PTFE, etc. with the addition of various lubricants and impregnating agents. A wide variety of materials are available, each with different settlement properties. The axial compression also creates a radial compression of the sealing element against the valve stem and the valve housing.However, these types of sealing arrangements have the disadvantage that they are subject to wear and settlement during operation and will eventually become leaky as the packing's contact pressure decreases. Automatic axial retensioning of the packing can be achieved using a preloaded spring element.

[0003] It is desirable to detect an early deterioration in the tightness of the sealing arrangement. For example, US Pat. No. 5,549,305 A discloses a soot blower which comprises a feed pipe for delivering liquid to a concentrically mounted lance pipe, wherein a sealing arrangement prevents the liquid from escaping from the system. The sealing arrangement has a packing between the inner surface of the lance pipe and the outer surface of the feed pipe. In order to maintain the sealing effect of the packing during wear, a pressure sleeve engaged with the packing is preloaded by a plurality of coil springs. The springs are preloaded between a fixed and a movable stop of a preloading device connected to the pressure sleeve. A desired contact force on the packing can be adjusted via the number of springs.In one embodiment, elongation of the springs, which occurs due to the decreasing preload force, which in turn is due to wear of the packing, can be detected by a bolt threaded into the movable stop and extending through a sleeve attached to the fixed stop. The elongation of the springs increases the distance between the fixed stop and the movable stop, causing a head of the bolt to be drawn into the sleeve until it disappears. This is an indication or signal that the springs need to be retensioned.

[0004] DE 10 2006 022 212 A1 describes a spring assembly of a sealing assembly that, for example, seals a valve stem against a valve body. A packing of the sealing assembly is compressed by means of a pressure sleeve, which is acted upon by a pressure element in the form of a compression flange, whereby the pressure element cooperates with the spring assembly. The spring assembly is connected to the compression flange via a connecting element anchored in the valve body. The connecting element, designed as a threaded bolt, passes through the spring assembly and the compression flange. Using a threaded nut, which is screwed to the threaded bolt with the spring assembly interposed, the pressure applied to the pressure sleeve and consequently the packing can be varied.The spring assembly includes a spring element that can be compressed via the threaded nut to provide the necessary preload. The spring element is housed in a housing and secured within the housing by a cover. The cover and the housing can move relative to each other in the axial direction while simultaneously compressing / relaxing the spring element.

[0005] US 2015 0369 388 A1 describes a valve configuration comprising a sealing arrangement whose packing is compressed via a pressure sleeve having a pressure element in the form of a compression flange. The compression flange is connected to a valve housing via connecting elements or bolts. By tightening the screw nuts screwed to the respective bolts, the pressure applied to the packing can be increased, with a spring element arranged between the screw nut and the bolt.

[0006] EP 2 753 908 B1 describes a control valve unit with a sealing arrangement in which the compression on a packing is achieved by using elongated bolts which are connected at one end to a valve housing and at the other end to a compression flange.

[0007] The compression flange rests on a compression sleeve of the sealing assembly. Tightening the bolted nuts increases the pressure on the packing. A spring element is positioned between the bolts and an outer surface of the flange, compensating for changes in the packing to maintain the required pressure and seal against the valve stem.

[0008] DE 10 2014 015 888 A1 describes a control valve unit having the generic features. The control valve unit comprises a valve stem sealed against a valve housing by a sealing arrangement. The sealing arrangement has a compressible packing axially received between a counterbearing on the valve housing and a pressure sleeve. The pressure sleeve is mounted for axial movement relative to the valve housing. A spring element transmits a contact pressure to the packing via the pressure sleeve. The spring element is supported against a preloading device whose distance from the counterbearing is adjustable. This allows the contact pressure of the spring element acting on the pressure sleeve to be adjusted. A measuring device detects a change in the position of the pressure sleeve relative to the counterbearing.

[0009] These types of sealing arrangements are subject to wear and settlement during operation. As a result, the axial compression and the associated radial sealing forces on the valve stem and valve body decrease over time, creating the risk of process fluid escaping from the valve body. In the event of wear and settlement of the packing, the packing can be automatically axially retensioned via the preloaded spring element acting on the pressure sleeve. The forces of the spring element decrease with increasing elongation according to the spring characteristic curve.

[0010] A generic control valve unit having the features of the preamble of claim 1 is disclosed in US 3 968 970 A.

[0011] It is an object of the invention to further develop a control valve unit of the type specified in claim 1 in such a way that an improved adjustability of a tightness of a sealing arrangement of different packings is possible compared to the prior art.

[0012] The problem is solved by the characterizing features of claim 1 in conjunction with its preamble features.

[0013] The subclaims constitute an advantageous further development of the invention.

[0014] In a known manner, a control valve unit comprises a sealing arrangement that seals a valve stem against a valve housing. The sealing arrangement has a stuffing box in which an axially compressible packing is accommodated between a counterbearing on the valve housing and a pressure sleeve mounted so as to be axially movable relative to the valve housing. A contact force is exerted on the pressure sleeve by at least one spring element, which is supported at one end on a preloading device and at the other end on the pressure sleeve. The spring element is supported on the pressure sleeve via a pressure element, for example an annular shoulder. The preloading device is adjustable in terms of its distance from the counterbearing, for example by means of adjusting screws, whereby a corresponding contact force of the spring element can be adjusted.If the tightness of the packing decreases, the pressure sleeve is moved axially towards the counter bearing by means of the contact force of the spring element, whereby this relative movement can be used to conclude that the packing is wearing accordingly.

[0015] The valve housing can, for example, be constructed as a single piece, so that the packing receptacle, fluidic connections, and a valve seat are housed within the one-piece valve housing. It is also possible for the valve housing to comprise a base housing containing the valve seat and fluidic connections, as well as a valve cover that serves to accommodate the packing and valve stem. The valve cover and the base housing are then sealed together. The control valve unit and the fluidic connections can be designed for gases or liquids.

[0016] According to the invention, the spring element is arranged axially between a first stop and a second stop of the pretensioning device, wherein in a preassembled state of the pretensioning device the spring element is supported under pretension on the first stop and on the second stop, wherein in an operating state of the control valve unit the second stop is arranged at a fixed distance from the first stop in the direction of the counter bearing and wherein the axial change in position of the pressure sleeve is limited by the second stop arranged at a distance from the pressure element in the direction of the counter bearing. The spring element extending in the axial direction, for example a disc spring assembly or a helical spring, is clamped axially between the first stop and the second stop in the preassembled state of the pretensioning device and exerts no contact force on either the pressure sleeve or the packing.The spring element can be mounted in the preload device under preload and generates a specific preload force even in the resting state, i.e., without exerting a contact force on the pressure sleeve. Consequently, the spring element can be installed in the control valve unit in a preloaded state, i.e., already exhibiting a high spring force.

[0017] The second stop is arranged at a fixed distance from the first stop, ie an extension between the first stop and the second stop is constant, and the spring element is installed in the preloading device in the control valve with a constant installation space, which can in particular have a small axial extension.

[0018] In order to achieve an operating state of the control valve unit, the preload device is installed and the packing is clamped. When the preload device is installed in the control valve unit, the axial distance between the preload device and the counter bearing is adjusted, i.e. the first stop and the second stop move axially towards the counter bearing. The pressure element is arranged in a fixed position relative to the pressure sleeve. This means that it remains in the same axial position. The second stop moves away from the pressure element in the direction of the counter bearing so that the spring element is now supported on the pressure sleeve via the pressure element and clamps the packing. The axial distance between the first stop and the pressure element decreases. The spring element is further compressed between the first stop and the pressure element. This increases the preload force of the spring element.Advantageously, the preloading device according to the invention allows the spring element to be installed in the control valve unit already with a high preload force, whereby the contact pressure of the spring element can be further increased during installation in the control valve unit. In this way, the preload force of the spring element can be adjusted to suit the design conditions of the sealing packing. Depending on the packing composition, the preload force should not be set too tightly, for example, to minimize friction on the valve stem. However, it must be set high enough to ensure that radial sealing forces prevent the escape of a process fluid.

[0019] When the preload device is installed, the second stop moves away from the pressure element in the direction of the counter bearing and the axial distance between the second stop and the pressure element increases. Due to the energy of the preload, the spring element exerts a contact force on the pressure element and consequently on the pressure sleeve when the preload device is installed, in order to move the pressure sleeve axially towards the counter bearing in the event of wear and / or settling of the packing. When the contact force decreases, the packing is automatically retensioned by the preload force of the spring element until an axial change in position of the pressure sleeve or the pressure element is stopped by the second stop. The second stop therefore serves to limit the axial spring deflection and to limit the axial change in position of the pressure sleeve.This allows the sealing gap between the valve stem and the valve body to be adjusted to a minimum, adapted to the operating conditions, and, if the packing tightness decreases, can be retightened in a controlled manner depending on the settling characteristics and service life of the packing. When the spring element is deflected to its maximum extent up to the limiting second stop, the spring element can either be retightened using the preloading device or the exhausted packing can be replaced to prevent packing leakage due to a decrease in the packing tightness. Limiting the positional change of the pressure sleeve advantageously enables good adjustability of the contact pressure of different packings and prevents packing leakage at an early stage.

[0020] The pressure element is preferably designed as a compression flange. The compression flange can, for example, be designed as a plate-shaped pressure plate. It serves to evenly distribute the contact force across the pressure sleeve and consequently across the packing. A spherical connecting surface between the pressure element and the pressure sleeve, which in particular has a spherical annular shoulder, can serve to transmit the force of the spring element in the event of asymmetry in the axial direction. The compression flange prevents the spring element from exerting asymmetrical loads on the pressure sleeve. The pressure sleeve can, for example, be designed with a projection, an annular shoulder, or the like, on which the compression flange is supported and at least partially radially surrounds the pressure sleeve. It is also conceivable for the compression flange to be formed integrally with the pressure sleeve.For example, a radial projection of the pressure sleeve can form the compression flange.

[0021] The pretensioning device preferably has a housing which comprises an adjusting cover which forms the first stop and is connected to an adjusting body which forms the second stop. The adjusting cover ensures that the spring element is held captive in the adjusting body. The adjusting cover and the adjusting body can be connected to one another in a sealing and detachable manner, for example via screw connections. The two-part design of the pretensioning device enables the spring element to be easily clamped between the first stop of the adjusting cover and the second stop of the adjusting body of the pretensioning device, particularly in small installation spaces. Advantageously, it is possible to install the pretensioning device as a preassembled unit in the control valve unit, for example to reduce the effort required for installation work at the location of the control valve unit.

[0022] According to a preferred embodiment, the adjusting body has an internal adjusting thread which, when the control valve unit is in the assembled state, engages with an external thread of the valve housing. The adjusting body can be screwed in relative to the valve housing, for example, using a torque wrench or a defined number of revolutions of the adjusting body, e.g. 6 to 7 rotations. This results in the pretensioning device, i.e. the first stop and the second stop, moving axially towards the counterbearing. As a result, the second stop moves away from the pressure element which is arranged in a fixed position relative to the pressure sleeve and on which the spring element is directly supported, and the spring element is further compressed between the first stop and the pressure element. A required, predefined spring force which the spring element is intended to achieve in order to tension the packing depends on the design or configuration of the packing.Thus, the preloading device according to the invention, which is adjustable in axial distance from the counter bearing via the adjusting thread, allows a preload force of the spring element to be adjusted according to the operating and / or design conditions of the packing.

[0023] Preferably, the preloading device is connected to a measuring device comprising a measuring element for detecting the axial position change of the pressure sleeve. The measuring device can, for example, be permanently connected to the preloading device, i.e., the measuring device can be preassembled together with the preloading device as a single component. This contributes to simplified assembly of the control valve unit.

[0024] Alternatively, the measuring device can be detachably connected to the preload device. They can be screwed or clipped together, for example. This has the advantage that the measuring device is only connected to the preload device after the actuator and valve housing have been screwed together, which prevents, in particular, twisting of the measuring device's wiring.

[0025] The measuring device comprises a measuring element that detects the axial position change of the pressure sleeve relative to the preloading device or the second stop. In particular, the detection can be based on a contactless, for example inductive, capacitive, or magnetic function or the like. It is also conceivable for the measuring element to be designed as a switch that is actuated by an actuating means to detect the position change of the pressure sleeve.

[0026] According to a preferred embodiment, the measuring element is designed as a magnetically sensitive sensor that interacts with a magnet connected to the pressure sleeve. The sensor detects a relative change in the position of the pressure sleeve via the magnet connected to the pressure sleeve in a contactless and wear-free manner. Using such a sensor, both step-by-step and continuous position detection of the pressure sleeve is possible. The magnetic sensor can be designed, for example, as an xMR chip or a Hall-effect sensor. Magnetic sensors are advantageously insensitive to temperature fluctuations as well as dust and moisture in harsh environments. They exhibit high accuracy, reliability, and robustness.

[0027] The measuring device preferably has a sensor housing for accommodating the sensor. The sensor housing forms a guide groove in which the magnet is guided for axial movement. The magnet is connected to the pressure sleeve via a magnetically conductive adhesive ring that engages at least partially radially in the guide groove. The sensor is arranged in a fixed position on the sensor housing. The sensor housing contributes to the robustness and durability of the measuring device in harsh outdoor applications and / or in difficult environments, as the sensor is mounted in a secure area.

[0028] The magnet is guided axially movable and securely in the guide groove of the sensor housing. The sensor housing has a cutout along a long side arranged on the pressure sleeve, which forms the axial guide groove. The magnet and a boundary of the guide groove formed by the sensor housing have almost complementary shapes, whereby the magnet is arranged securely and with almost no play in the guide groove extending in the axial direction. The magnet can, for example, be cylindrical in the axial direction, with the boundary of the guide groove in cross section encompassing a hole circle forming the guide groove at least partially beyond an equator. The sensor housing can, for example, form a boundary of the guide groove that is crescent-shaped in cross section.

[0029] The magnet is connected to the pressure sleeve via a magnetically conductive adhesive ring. At one free end of the pressure sleeve, the adhesive ring is connected to the pressure sleeve, for example, via a fastening ring. The adhesive ring is arranged, in particular, on the front side of the pressure sleeve and radially surrounds the valve rod. Thus, the axial change in the position of the pressure sleeve causes an axial change in the position of the magnet.

[0030] Viewed in the axial direction, the boundary of the guide groove formed by the sensor housing is arranged on the pressure sleeve without overlapping with the adhesive ring. In the radial direction, the adhesive ring penetrates at least partially into the guide groove. This allows the pressure sleeve to carry the magnet adhering to the adhesive ring axially in the guide groove when it moves due to wear on the packing.

[0031] The axial position change of the pressure sleeve causes an axial position change of the magnet relative to the sensor, which is fixedly mounted on the preload device. The magnet is housed in the sensor housing, spatially separated from the sensor, and always remains at a fixed radial distance relative to the sensor via the axial guide in the guide groove. This enables stable distance measurement of the measuring device in the axial direction. This ensures reliable indication of packing wear via the magnetic sensor.

[0032] The magnet is preferably arranged so as to be rotatable relative to the adhesive ring in the circumferential direction of the valve stem. The adjusting body of the preloading device, which is in particular designed as a single assembly together with the measuring device, is screwed relative to the valve housing to adjust the spring preload force. This means that the preloading device, together with the sensor housing, is rotated several times about its axis via the adjusting body, with the sensor housing entraining the magnet in the rotational movement in the circumferential direction of the valve stem on the adhesive ring. The guide groove of the sensor housing is arranged on the pressure sleeve in such a way that when the preloading device rotates about its axis, the magnet, adhering to the adhesive ring, rotates around the valve rod.

[0033] According to a preferred embodiment, the measuring element communicates bidirectionally with a control unit, which is communicatively connected to an operating unit of the measuring device. The operating unit has at least one display unit and a calibration button. The operating unit can be designed, for example, as a mobile device that communicates wirelessly with the control unit.

[0034] The measuring element, which is particularly designed as a magnetic sensor, communicates with the control unit for processing measurement data from the measuring element. The sensor can, for example, be designed with integrated microelectronics, which processes the measurement data in the sensor and forwards it, in particular, to the display unit so that a user can read it. It is possible for the sensor and the control unit to be integrated, for example, on a single chip. It is also conceivable for the sensor to be connected to an external control unit, i.e., the sensor and the control unit are designed separately.

[0035] The calibration button on the control unit allows the sensor to be set to a zero position very precisely and electronically. This allows the sensor to detect any relative movement of the magnet to the sensor. The control unit processes the sensor's measurement data using evaluation electronics and forwards the pressure sleeve's position values ​​to the display unit. A position value of the pressure sleeve can now be read at any time during operation. Both discrete position detection and continuous position detection of the pressure sleeve over time are possible. This allows the user of the control valve unit to read the change in position of the pressure sleeve and determine whether the packing is wearing. If the position value reaches a predefined threshold, an alarm can be triggered, for example, so that the packing can be either retightened or replaced.

[0036] According to a preferred embodiment, the control unit detects the contact pressure of the packing via a force-displacement characteristic curve of the spring element. The force-displacement characteristic curve of the spring element can be stored in a data memory of the control unit. The force-displacement characteristic curve describes the relationship between spring force and spring displacement and shows how the spring element behaves during operation. Depending on the design, the spring element behaves differently during operation. The spring element can in particular be designed as a compact disc spring package, which is suitable for installation in confined spaces where high forces are nevertheless required. Alternatively, it is also conceivable for the spring element to be designed as a helical compression spring. Based on the measured axial change in position of the pressure sleeve, the remaining preload force of the spring element over time can be displayed via the force-displacement characteristic curve during operation.This also allows the axial change in the force acting on the packing to be recorded. For example, it is advantageous to monitor the contact force via the display unit during the assembly process and adjust the actuator accordingly.

[0037] In this way, the force-displacement characteristic curve together with the sensor can be used to precisely adjust the axial tension force of the spring element and thus achieve a contact pressure on the packing that is adapted to the operating conditions. Before installation in the control valve unit, the spring element in the preload device is preloaded to a specific contact pressure, with the sensor calibrated as a force sensor. The preload force of the spring element in the pre-assembled state of the preload device can be displayed, for example, via the operating unit. Then, when the preload device is installed in the control valve unit, the actuator is screwed into the valve housing. The sensor can be zeroed relative to the magnet at a specific screw-in point, for example at the screw-in point where the spring element rests against the pressure sleeve with the pressure element in between without any contact force and any contact force on the pressure sleeve is prevented by the second stop.At this screw-in point, the magnet is located in an area of ​​the sensor's optimal start of measurement, for example, in its lowest position relative to the sensor. When the preload device is rotated, the first stop, the second stop, and the sensor, which is permanently connected to the preload device, move towards the counter bearing. The sensor moves relative to the magnet, the second stop moves away from the pressure element, and the first stop presses the spring element against the pressure sleeve via the pressure element. This compresses the spring element even further. The preload device can be rotated further into the valve housing up to a predefined sensor value, which corresponds to a specific preload force of the spring element, in order to achieve a desired, predefined axial contact force against the packing.The contact pressure acting on the packing can be continuously displayed on the control unit during assembly of the preloading device and during the operating state of the control valve unit. The preloading device according to the invention can be easily adjusted to the operating conditions of packings of different manufacture and lengths. Furthermore, during the retightening process of the spring element, the contact pressure on the packing can be monitored via the display unit, and the actuating body can be retightened according to the contact pressure displayed.

[0038] Preferably, the control unit is communicatively connected to at least one actuator, which is connected to the adjusting body for adjusting the preload force. The actuator converts data received from the control unit into a mechanical movement. This means that the actuator causes the adjusting body to rotate in order to adjust the contact pressure acting on the packing. This can occur, for example, when a preset threshold for the change in position of the pressure sleeve and / or the preload force of the spring element is reached. Advantageously, the preload force of the spring element is adjusted automatically by adjusting the preload device or tightening the adjusting body by means of an actuator.

[0039] Further advantages, features and possible applications of the present invention will become apparent from the following description in conjunction with the embodiments shown in the drawings.

[0040] In the description, claims, and drawings, the terms and associated reference symbols used in the list of reference symbols below are used. In the drawings, the following definitions apply: Fig. 1 shows a detail of a sectional view of a control valve unit according to the invention with a pretensioning device in a preassembled state; Fig. 2 shows a detail of a sectional view of a control valve unit according to the invention with a pretensioning device in an operating state of the control valve unit; Fig. 3 shows a perspective top view of a pretensioning device of a control valve unit according to the invention, viewed obliquely from above; and Fig. 4 shows a top view of a pretensioning device of a control valve unit according to the invention.

[0041] Fig. 1 shows a section of a control valve unit 10, which has a valve rod 12 and a valve housing 14. The valve rod 12 is sealed against the valve housing 14 by a sealing arrangement having a packing 16.

[0042] The packing 16 is arranged axially between a counterbearing 18 and a pressure sleeve 20. The pressure sleeve 20 is mounted axially displaceably relative to the valve housing 14, whereby the counterbearing 18 is part of the valve housing 14 or can be fixedly arranged in the valve housing 14. The pressure sleeve 20 allows the packing 16 to be axially compressed, thereby achieving an axial and radial sealing effect of the packing 16.

[0043] The contact pressure for compressing the packing 16 is provided by a spring element 22, which in this case is designed as a centered disc spring assembly. In this case, the spring element 22 radially surrounds the valve rod 12. The spring element 22 is supported on a pretensioning device 24. The pretensioning device 24 has a housing that forms an adjusting body 26 that is sealingly connected to an adjusting cover 28. A first end of the spring element 22 is supported on the adjusting cover 28, which forms a first stop 40. The other end of the spring element 22 is supported in this case with the interposition of a pressure element 30, which in this case is designed as a pressure plate or a compression flange, on a second stop 32 formed by the adjusting body 26.

[0044] In the pre-assembled state of the pre-tensioning device 24, particularly in small installation spaces, the spring element 22 is axially pre-tensioned between the first stop 40 and the second stop 32, so that it already generates a pre-tensioning force in the rest state, i.e., before it exerts a contact force on the pressure sleeve 20. In the present case, the spring element 22 is installed in the control valve unit 10 in a pre-tensioned state.

[0045] In order to assemble the preloading device 24 into the control valve unit 10, the actuating body 26 is formed on an inner side with an actuating thread 34 which engages with an external thread 36 of the valve housing 14. By tightening the actuating body 26, the actuating thread 34 is screwed into the external thread 36 until a screw-in point with noticeable resistance is reached. At this screw-in point of the preloading device 24 with the valve housing 14, the pressure sleeve 20 rests directly on the packing 16 without any contact force, with the pressure element 30 in this case resting on the pressure sleeve 20 via a projection 38. At this screw-in point, the spring element 22 is clamped between the first stop 40 and the second stop 32 without exerting any axial contact force on the pressure sleeve 20 or the packing 16.the second stop 32 is in a starting position, which can be defined, for example, as a zero position for measuring a change in position of the pressure sleeve 20 due to the settlement properties of the packing 16.

[0046] In this case, a circumferential fastening ring 42 is arranged on an end of the pressure sleeve 20 protruding from the pretensioning device 24. On its end face, the fastening ring 42 has an adhesive ring 44 made of magnetically conductive material. A cylindrical magnet 46 adheres to the adhesive ring 44 by magnetic force. The magnet 46 is accommodated in a guide groove 48 in which it can move axially with almost no friction or play. This allows it to be constantly driven in the guide groove 48 during an axial change in position or movement of the pressure sleeve 20.

[0047] The guide groove 48 is formed by a sensor housing 50 of a measuring device 52, which is connected to the preloading device 24 and supplied with power via a cable connection 58. The cable connection 58 can also be used, for example, to transmit data, in particular to other components of the control valve unit. In the present case, the sensor housing 50 is firmly connected to the adjusting cover 28 of the preloading device 24. It is conceivable that the measuring device 52 and the preloading device 24 form, for example, a preassembled unit.

[0048] A magnetically sensitive sensor 54 is arranged in the sensor housing 50, which detects the axial movement of the magnet 46 without contact. The sensor 54 can be designed, in particular, as an xMR chip or Hall effect sensor. The sensor housing 50 enables a close, fixed distance to be maintained between the magnet 46 and the sensor 54 in the radial direction of the preloading device 24 in order to reliably detect an axial displacement measurement or position of the magnet 46. In the present case, the magnet 46 is located in its axially lowest position relative to the sensor 54 or in a range of an optimal start of measurement of the sensor 54.

[0049] The sensor 54 communicates bidirectionally with a control unit (not shown here), whose evaluation electronics processes the measurement data from the sensor 54. In particular, the control unit and the sensor 54 can be integrated together on a chip. The control unit is communicatively connected to an operating unit 56 of the measuring device 52 (also not shown here). The operating unit 56 has a calibration button with which the sensor 54 can be zeroed, for example, in the above-described starting position of the pretensioning device 24. The magnet 46 is located in a specific position relative to the sensor 54. Through calibration, the sensor 54 can monitor a relative movement of the magnet 46 and consequently a relative axial movement of the pressure sleeve 20, wherein the evaluated measurement data is shown on a display unit of the operating unit 56.

[0050] In Fig. 2 The sealing arrangement of the control valve unit 10 is shown in an operating state of the control valve unit 10, ie in the tensioned state of the packing 16. An axial spring tension on the packing 16 can be adjusted via the pretensioning device 24. The actuating body 26 is made of the, for example, Fig. 1 The first stop 40 and the second stop 32 move towards the counter bearing 18. As a result, the second stop 32 points in relation to the zero position described above. Fig. 1 described starting position has an axial distance from the pressure element 30 and the spring element 22 is further compressed between the adjusting cover 28 and the pressure element 30, so that the preload force of the spring element 22 and consequently a contact force on the pressure sleeve 20 and on the packing 16 is increased. The axial movement of the preload device 24 in the direction of the counter bearing 18 also results in the pressure sleeve 20 extending out of the adjusting cover 28 of the preload device 24, and in the magnet 46 carried by the pressure sleeve 20 moving relative to the sensor 54. The preload device 24 was here compared to Fig. 1 screwed into the valve housing 14 via several rotations of the actuating body 26, whereby the magnet 46 is arranged directly opposite the sensor 54 at the same axial height.

[0051] To precisely adjust the contact pressure with which the spring element 22 is to act on the packing 16, the sensor 54 can be used in combination with a force-displacement characteristic curve for the spring element 22. The force-displacement characteristic curve is stored, for example, in a memory of the control unit, and the sensor 54 is calibrated as a force sensor before the preload device is installed. The spring element 22 is preloaded in the preload device 24 before installation in the control valve unit 10 to a desired preload force, which can be read, for example, via the operating unit 56 (not shown here). An axial change in the contact pressure of the spring element 22 can be determined via the relative axial displacement of the magnet 46 from the zero position described above as an example. In this way, the actuating body 26 can be moved up to a predefined value of the sensor 54, iea specific preload force corresponding to a specific axial change in the position of the magnet 46, are screwed into the valve housing 14. The axial distance over which the magnet 46 moves relative to the sensor 54 corresponds to a compression of the spring element 22, and thus to a specific change in the preload force with which the spring element 22 now acts on the packing 16 after the second stop 32 has been arranged at an axial distance from the compression flange 30 by rotating the actuating body 26 in the direction of the counter bearing 18. The force-displacement characteristic curve can be used to precisely set a predefined axial pressure of the spring element 22 against the packing 16 in order to work with a pressure force adapted to the operating conditions on packings 16 of different manufacture and lengths.

[0052] It is conceivable that the measuring device 52 may have a battery or rechargeable battery in addition to the cable connection 58. This has the advantage that the sensor 54 and the operating unit 56 are supplied with power even before the entire control valve unit 10 is put into operation. This allows the contact pressure acting on the packing 16 to be displayed on the display unit during the installation of the preload device 24 into the control valve unit 10 before the control valve unit 10 is put into operation.

[0053] During commissioning of the control valve unit 10, the spring-loaded pressure sleeve 20 exhibits an axial movement relative to the second stop 32 due to the wear and / or settlement characteristics of the packing 16. This movement is proportional to a settlement path of the packing 16 and allows conclusions to be drawn about the state of wear of the packing 16. During the axial movement of the pressure sleeve 20, the magnet 46 is always driven along. Consequently, the axial movement of the magnet 46 relative to the sensor 54 corresponds to the movement of the pressure sleeve 20 relative to the second stop 32. During operation, a sensor value corresponding to a position of the pressure sleeve 20 can now be read from the display unit at any time. In this way, the settlement process of the packing 16 can be measured and monitored over time. The force-displacement characteristic curve of the spring element 22 can be used to derive the preload force with which the spring element 22 acts on the packing 16 and its change over time.This preload force can also be displayed and monitored.

[0054] The pressure sleeve 20 yields to the contact forces of the spring element 22 until the pressure element 30 rests against the second stop 32. The second stop 32 limits the deflection of the preloaded spring element 22 and thus the axial positional change of the pressure sleeve 20. In this way, the second stop 32 can limit the spring elongation of the spring element 22 and thus a positional change of the pressure sleeve 20 in order to prevent a deterioration in the tightness of the packing 16 and the escape of the process fluid.

[0055] If a critical setting value of the packing 16 is exceeded and / or if a predefined preload force is exceeded and / or undershot, an alarm can be triggered, for example. Depending on the nature and / or design of the packing 16, either its service life is exhausted and it must be replaced, or it must be retightened. During the retightening process, the contact force acting on the packing 16 can be displayed and monitored via the control unit 56, so that the actuating body 26 is retightened according to the desired contact force. For example, it is possible to automatically retighten the preload device 24 to the desired contact force by means of an actuator (not shown here) acting on the actuating body 26.

[0056] In Fig. 3 is a perspective top view of a pretensioning device 24 of a control valve unit 10 according to the invention according to Fig.1 Viewed obliquely from above. The preloading device 24 radially encloses the spring-loaded pressure sleeve 20 with the adjusting cover 28 and the adjusting body 26. The adjusting cover 28 is detachably connected to the adjusting body 26 via screw connections 60. The spring element 22, not shown here, is clamped under axial preload between the first stop 40 of the adjusting cover 28 and the second stop 32 of the adjusting body 26 in the preloading device 24.

[0057] The adjusting body 26 is connected to the valve housing 14 via the internal adjusting thread 34 (not shown here). For adjusting the pretensioning device 24, the adjusting body 26 is designed with a circumferential surface that has a drive profile for an open-end wrench. It is also conceivable for the circumferential surface to have a profile for another tool, for example, a nose-hook wrench. The predefined pretensioning force with which the spring element 22 is to act on the packing 16 when the pretensioning device 24 is in the assembled state can be adjusted by a defined number of revolutions of the adjusting body 26 relative to the valve housing 14.

[0058] At the free end of the pressure sleeve 20, which extends out of the pretensioning device 24, the fastening ring 42 is arranged, over which the particularly ferromagnetic adhesive ring 44 is arranged on the end face of the pressure sleeve 20. The adhesive ring 44 radially surrounds the valve rod 12. The magnet 46 of the measuring device 52 is magnetically connected to the adhesive ring 44 and is guided axially movably and securely in the guide groove 48 formed by the sensor housing 50.

[0059] In the present case, the magnet 46 is cylindrical and arranged in the guide groove 48 with virtually no play. The sensor housing 50 has a complementary shape to the magnet 46 in the region of the guide groove 48 and partially surrounds it radially. The guide groove 48, which extends in the axial direction, is arranged directly on a circumferential side of the fastening ring 42 on the adhesive ring 44. The adhesive ring 44 partially penetrates radially into the guide groove 48. In this way, the pressure sleeve 20 always entrains the magnet 46 during an axial movement due to wear of the packing 16.

[0060] The axial movement of the pressure sleeve 20 can be determined by the relative movement of the magnet 46 relative to the sensor 54. To ensure reliable axial displacement measurement of the magnet 46, the sensor 54 is arranged in a fixed position in the sensor housing 50 of the measuring device 52 at a fixed radial distance from the magnet 46.

[0061] Fig. 4 shows a plan view of a pretensioning device 24 of a control valve unit 10 according to the invention Fig. 3from above. In the present embodiment, the measuring device 52 is designed as a structural unit with the pretensioning device 24. When tightening and retightening the packing 16, the pretensioning device 24 is rotated via the adjusting body 26. The sensor housing 50 encloses the magnet 46 beyond an equator of the magnet 46. The magnet 46 is arranged rotatably relative to the adhesive ring 44 in the circumferential direction of the valve stem 12, i.e., with one rotation of the adjusting body 26, the magnet 46 rotates on the adhesive ring 44, adhering to the valve rod 12. Via the sensor housing 50, which is firmly connected to the adjusting cover 28, the magnet 46 remains radially in the same position relative to the sensor 54 despite the rotation of the pretensioning device 24 relative to the valve housing 14. The measuring device 52, i.e.The sensor housing 50, the sensor 54, the magnet 46 and the cable connection 58 are fixedly connected to the adjusting cover 28 and rotate as a unit around the valve rod 12 when the adjusting body 26 is rotated.

[0062] In this case, an operating unit 56 is arranged on the sensor housing 50. It includes a display unit for displaying the setting process and / or the contact pressure acting on the packing 16. It is conceivable that the operating unit 56 is designed, for example, as a mobile device that communicates wirelessly with the control unit. List of reference symbols

[0063] 10Control valve unit 12Valve rod 14Valve housing 16Packing 18Counter bearing 20Pressure sleeve 22Spring element 24Preload device 26Actuator 28Adjusting cover 30Pressure element 32Second stop 34Adjusting thread 36External thread 38Protrusion 40First stop 42Fastening ring 44Adhesive ring 46Magnet 48Guide groove 50Sensor housing 52Measuring device 54Sensor 56Operating unit 58Cable connection 60Screw connection

Claims

1. Control valve unit (10) comprising a valve rod (12) which is sealed off from a valve housing (14) by means of a sealing arrangement, which sealing arrangement has a packing (16) that is mounted axially between a pressure sleeve (20) and a counter bearing (18) on the valve housing (14), wherein the pressure sleeve (20) is mounted so as to be axially movable relative to the valve housing (14) and transmits to the packing (16) a contact pressure applied to the pressure sleeve (20) by a spring element (22) via a pressure element (30), and wherein the spring element (22) is supported on a pretensioning means (24) the distance of which from the counterbearing (18) can be adjusted, thus allowing adjustment of the contact pressure of the spring element (22) acting on the pressure sleeve (20), wherein the spring element (22) is arranged axially between a first stop (40) and a second stop (32) of the pretensioning means (24), wherein, in a preassembled state of the pretensioning means (24), the spring element (22) rests against the first stop (40) and the second stop (32) under pretension, characterized in that, in an operating state of the control valve unit (10), the second stop (32) is arranged at a fixed distance from the first stop (40) in the direction of the counter bearing (18) and wherein the axial change in position of the pressure sleeve (20) is limited by the second stop (32) that is arranged at a distance from the pressure element (30) in the direction of the counter bearing (18).

2. Control valve unit according to claim 1, characterized in that the pressure element (30) is designed as a compression flange.

3. Control valve unit according to any one of claims 1 or 2 above, characterized in that the pretensioning means (24) has a housing which comprises an adjustable cover (28) that constitutes the first stop (40) and is connected to an adjusting member (26) that constitutes the second stop (32).

4. Control valve unit according to claim 3, characterized in that the adjusting member (26) has an internal adjusting thread (34) which, in an assembled state of the control valve unit (10), is in engagement with an external thread (36) of the valve housing (14).

5. Control valve unit according to any one of claims 1 to 4 above, characterized in that the pretensioning means (24) is connected to a measuring device (52) which comprises a measuring element for detecting the axial change in position of the pressure sleeve (20).

6. Control valve unit according to claim 5, characterized in that the measuring element is designed as a magnetically sensitive sensor (54) which interacts with a magnet (46) that is connected to the pressure sleeve (20).

7. Control valve unit according to claim 6, characterized in that the measuring device (52) has a sensor housing (50) for arranging the sensor (54), which sensor housing (50) has a guide groove (48) in which the magnet (46) is guided so as to be axially movable, and which magnet (46) is connected to the pressure sleeve (20) via a magnetically conductive fastening ring (44) at least part of which engages radially in the guide groove (48).

8. Control valve unit according to claim 7, characterized in that the magnet (46) is arranged so as to be rotatable relative to the fastening ring (44) in the circumferential direction of the valve rod (12).

9. Control valve unit according to any one of claims 5 to 8 above, characterized in that the measuring element communicates bidirectionally with a control unit which is connected in a communicating manner to an operating unit (56) of the measuring device (52), which operating unit (56) has at least one display unit and a calibration button.

10. Control valve unit according to claim 9, characterized in that the control unit detects a contact pressure of the packing (16) via a force-displacement characteristic of the spring element (22).

11. Control valve unit according to any one of claims 9 or 10 above, characterized in that the control unit is connected in a communicating manner to at least one actuator which is connected to the adjusting member (26) for adjusting the pretensioning force.