ELECTRONIC POSITION DISPLAY USING A TOOTH STRUCTURE MEASURING ARRANGEMENT

Description

[0001] The invention relates to a position and / or displacement measuring system for a control valve. Furthermore, the invention relates to a control valve for a process fluid flow in a process plant, such as a power plant, a chemical plant, a food processing plant, or the like.

[0002] Various systems are commonly used to determine absolute values ​​of a control valve's position. EP 3 161 361 A1 and EP 1 282 798 B1 disclose position sensors which are placed inside the yoke between an actuator and a valve housing, i.e. in an area protected from process fluid and easily accessible. EP 0 861 417 B1 describes a differential position sensor which can be attached in this way and uses a pair of magnetic position sensors equipped with various ramp- or wedge-shaped measuring components which taper in opposite directions to compensate for misalignments of the control rod, for example due to wear. The sensor is connected to the control rod perpendicular to the valve's stroke direction in the area of ​​the yoke. To measure the entire stroke length, the internal dimension of the yoke in the stroke direction is determined by the stroke length plus the width of the sensor component for sensing the position.For large strokes, the yoke must be made correspondingly long.

[0003] DE 199 39 497 C2 describes a control valve with a sensing unit for valve positioning. The actuator comprises a drive force unit, a yoke for a fixed connection to a valve, an actuator spindle for transmitting the movement of the drive force unit to the valve, and a sensing unit for detecting the valve position. Such actuators are operated pneumatically, hydraulically, or electrically, for example. The drive force unit converts electrical, thermal, or mechanical energy into the movement of an actuator rod to generate thrust. The sensing unit for measuring the valve position is usually mechanically coupled to the actuator rod. With the help of this sensing unit, the actual position of the valve can be monitored and controlled using a position controller, which often includes the sensing unit.The sensing unit comprises a magnetic track with a periodic structure integrated into the drive rod, a sensor connected to the yoke of the drive close to the magnetic track, which is suitable for detecting changing magnetic field lines, and at least one permanent magnet in the area of ​​the magnetic track and the sensor, whose magnetic field lines penetrate both the magnetic track and the sensor. The periodic structure of the magnetic track extends along the direction of movement of the drive rod. The sensor comprises two magnetoresistive sensors that are offset from one another in the direction of movement of the drive rod. The direction of movement can be determined using the two sensors. This type of position determination is an incremental position measuring system in which the magnetic track acts as a scale that does not contain any absolute information about the position, so that a counter orThe valve position is determined from a memory. To establish a defined reference point for the valve position, a trigger that is different from the magnetic track can be integrated into the drive spindle. This trigger triggers a characteristic signal at a predetermined position, which is taken into account by a logic circuit when recording initialization data.

[0004] In conventional control valves, the control rod is roughly aligned, typically on the actuator and / or on the valve housing, for example in the area of ​​an outlet opening, where sealing packings or similar may be provided. In a conventional control valve, the main extension direction of the control rod deviates from an orientation corresponding to an ideal linear measuring direction of a measuring device of the control valve. For example, the main extension direction in relation to the measuring axis of the measuring device can have a deviation in the form of an inclination in a first plane (inclination plane) that spans along the measuring axis and transversely thereto, a tilt angle in a second plane (tilt plane) that spans perpendicular to the inclination plane along the stroke direction, a radial offset in the inclination and / or tilt plane, and / or a rotational twist around the measuring axis.Actuators with a rotationally asymmetric shape, in particular, experience a torque from the process fluid that can twist the actuator stem. Due to dynamic behavior of the control valve, this deviation can change during operation. The mounting of a measuring device on the control valve is carried out within the framework of typical assembly tolerances, which are associated with unavoidable deviations between the measuring axis and the main extension of the actuating axis. Particularly with long strokes, large deviations between the main extension and the measuring axis can occur, leading to associated measurement errors. Such deviations from an ideal orientation of the main extension of the actuating stem can result in significant and / or unsystematic measurement errors or even lead to the failure of the measuring device.

[0005] US4756229A, KR100866069B1 and US5 568760A disclose position and / or displacement measuring systems according to the preamble of claim 1.

[0006] It is an object of the invention to overcome the disadvantages of the prior art, in particular to provide a particularly precise position and / or displacement measuring system which requires only a small installation space even with a long travel range.

[0007] This problem is solved by the subject matter of claim 1.

[0008] Accordingly, a position and / or distance measuring system is provided for a process fluid flow in a process plant, such as a power plant, a chemical plant, a food processing plant, or the like. The position and / or distance measuring system may be referred to below as a measuring system for short. The position and / or distance measuring system comprises a linearly movable actuating rod with at least one main extension direction and at least one coded track aligned along the main extension direction. An actuating rod typically has a main extension in a longitudinal or axial direction that is significantly greater than the extension of the actuating rod in the transverse or radial direction. For example, the actuating rod can have a cylindrical shape, with a cylinder radius and a main extension direction defined by the cylinder axis.The track is in particular fixedly connected to the actuating rod, preferably by means of a material fit, and is particularly preferably formed integrally with the actuating rod. In particular, the at least one track is incrementally or continuously encoded. Several tracks can be encoded identically or differently. The position and / or distance measuring system further comprises a measuring device with at least one preferably partially circular recess for linearly movable accommodation of the actuating rod and with at least one sensing unit arranged on the recess. The measuring device can have an ideal linear measuring axis along which a relative movement can be optimally detected by the at least one sensing unit of the measuring device. The sensing unit is designed and configured to detect the at least one track. Preferably, the at least one sensing unit is designed and configured for contact-free detection of the at least one track.

[0009] The position and / or displacement measuring system according to the invention comprises at least one or precisely one adjusting device arranged in the region of the recess for orienting the actuating rod relative to the measuring device. The adjusting device is preferably designed and configured to adjust the orientation of the main extension direction of the actuating rod corresponding to a measuring axis, in particular an ideal linear one, of the measuring device and / or to the stroke axis of the control valve. In particular, the adjusting device orients the main extension direction of the actuating rod parallel, preferably collinear, to the measuring axis of the measuring device.Preferably, the adjusting device is designed and configured to set an orientation of the adjusting rod corresponding to the measuring device, in particular parallel, preferably collinear, for a large part of the stroke of the adjusting rod, in particular at least 50%, preferably at least 70%, particularly preferably at least 80% or at least 90%, or to set it for the entire stroke of the adjusting rod.

[0010] With the position and / or displacement measuring system according to the invention, the actuating rod and the measuring device can be coordinated in such a way that the sensing unit can detect the track with particularly high accuracy. Even with actuating rods with a particularly long stroke, a consistently precise determination of the position of the actuating rod by the measuring device is guaranteed.

[0011] According to an expedient embodiment of a position and / or distance measuring system, the adjusting device is designed and configured to orient the actuating rod relative to the measuring device with a rotational offset with respect to the main extension direction of no more than ±10°, in particular no more than ±7°, preferably no more than ±4°. In an expedient embodiment, the adjusting device defines a rotational offset of the at least one track in relation to the at least one sensing device in the range of no more than ±7° or no more than ±9° relative to the measuring axis. In a preferred embodiment, the adjusting device defines a rotational offset of the at least one track in relation to the at least one sensing device in the range of no more than ±2° or no more than ±3° relative to the measuring axis. In particular, the adjusting device comprises a particularly positive-locking anti-twist device.A positive-locking anti-rotation device can be implemented, for example, as a single- or double-sided rail guide, a dovetail guide, or the like. The positive-locking anti-rotation device can comprise a linear bearing, in particular a linear ball bearing or linear plain bearing, for orienting the actuating rod relative to the measuring device.

[0012] In the position and / or distance measuring system, the adjusting device orients the actuating rod, which is preferably rotationally symmetrical around its outer circumference, relative to the recess without contact. The adjusting device preferably orients the actuating rod magnetically relative to the recess. In particular, the recess has at least one magnet, in particular a permanent magnet, which can be referred to as a directional magnet, and the actuating rod has a magnetizable or magnetic directional structure. The directional structure of the actuating rod extends, in particular continuously, preferably along the actuating rod, corresponding preferably parallel to the main direction of extension and / or to at least one track. In the direction of the main direction of extension, the directional structure extends in particular over a large part, in particular at least 50%, preferably at least 75%, particularly preferably at least 90%, of the length of the at least one track.The directional structure is designed and configured to cooperate with the adjustment device, in particular the anti-rotation device, in particular to ensure precise orientation of the actuating rod, in particular of the at least one track, relative to the measuring device, in particular of the at least one sensing device. The directional structure can be formed, for example, as a profile body extending continuously in the main direction of extent, such as a rib or groove. With the aid of one or more magnets on the measuring device, an actuating rod with a magnetizable or magnetic directional structure extending along its main direction of extent can be oriented in a particularly simple manner in order to counteract a rotational offset of the actuating rod, which is in particular rotationally symmetrical, and the at least one track provided thereon in relation to the measuring device, and / or to minimize or cancel the rotational offset.One or more magnets on the measuring device can additionally or alternatively cooperate with a corresponding magnetic or magnetizable directional structure on the adjusting rod in order to counteract a tilt and / or inclination angular offset of the adjusting rod and the at least one track provided thereon in relation to the measuring device or to minimize or cancel out the tilt and / or inclination angular offset. Alternatively or additionally, one or more magnets on the measuring device can cooperate with a corresponding magnetic or magnetizable directional structure on the adjusting rod in order to counteract, minimize or cancel out an offset of the adjusting rod transverse to the measuring axis and / or stroke axis, for example a parallel displacement. The arrangement of the adjustment device as a contact-free connection between the adjusting rod on the one hand and the measuring device on the other hand serves to prevent wear.

[0013] According to another embodiment of a position and / or displacement measuring system, which can be combined with the previous ones, the measuring device comprises a sleeve that defines the recess and supports at least one sensing unit. The sleeve is in particular partially circular, with the partially circular shape preferably extending over at least 120°, in particular at least 135°, preferably at least 180°, and / or no more than 270°, in particular no more than 225°, in the circumferential direction relative to the main extension direction around the actuating rod. Alternatively, the sleeve can be fully circular.

[0014] According to a further development of a position and / or distance measuring system in which the measuring device has a sleeve, the actuating rod comprises at least one coded second track aligned along the main direction of extent, wherein the second track is preferably arranged offset relative to the first track in the circumferential direction, for example offset by 60° or 90°. Preferably, the offset of the sensing units, i.e. their angular offset in the circumferential direction, corresponds to the offset of the tracks, which can also be referred to as track offset. Furthermore, the sleeve carries at least one second sensing unit, wherein the second sensing unit is designed and configured for preferably contact-free detection of the second track, wherein the second sensing unit is preferably arranged offset relative to the first sensing unit in the circumferential direction, for example offset by 60° or 90°.By providing two or more tracks on the actuating rod and at least one sensing device assigned to each track on the measuring device, redundant and / or combinable position and / or displacement measurements can be acquired using the measuring device. It is clear that the multiple track-sensing unit pairs can use the same measuring principle or different measuring principles, for example magnetic, haptic, capacitive, inductive and / or optical. Preferably, all sensing units operate contactlessly. The multiple tracks can be encoded in the same way or differently; in particular, the multiple tracks can be encoded continuously and / or discretely. Continuous encoding can, for example, be ramp-, wedge-, or curved. Discrete encoding can, for example, be incremental, modulated and / or periodic.The coding of the various tracks can be offset from one another with respect to the main extension direction. It may be preferable to provide two tracks encoded with a phase offset. By using multiple tracks, a significant increase in the quality of the informative value of the position and / or displacement measuring system can be achieved. In particular, in a preferred embodiment with two or more tracks, the measuring device can be designed and configured for absolute position determination. For example, it can be provided that a plurality of different, preferably continuous or discrete, unique track-measurement value combinations are provided along the course of the actuating rod in its main extension direction.In particular, preferably within a predetermined measuring range, each relative position of the adjusting rod with respect to the measuring device is assigned a single specific track-measurement value combination, on the basis of which the measuring device can clearly recognize the currently existing actual relative position.

[0015] In a further development of the position and / or distance measuring system that can be combined with the aforementioned embodiment, the sleeve has a first circular section on which the at least one sensing unit and optionally the second and / or a further sensing unit are arranged. Furthermore, the sleeve has at least a second circular section that is movably connected to the first circular section, preferably by means of a solid-state joint. The sleeve is preferably formed as a one-piece, integral body that comprises the first and second circular sections. It is provided that the first circular section has a partially circumferential opening for inserting the actuating rod and / or that the second circular section is arranged at least partially diametrically opposite the first circular section in the radial direction. The position can be held between the circular sections.The sleeve preferably has a measuring state in which the adjusting rod is held in the recess defined by the sleeve, particularly captively, and / or in which the at least one track is aligned, under the influence of the adjusting device, corresponding to the at least one sensing device associated with this track. The sleeve preferably has a release state in which the sleeve has an opening between the first and second circular segments through which the adjusting rod can be inserted into the recess. The sleeve is preferably adjustable between the release state and the measuring state, particularly by elastic deformation.

[0016] According to a preferred development of a position and / or displacement measuring system with a sleeve divided into circular segments, the adjustment device is arranged on the second circular segment. Optionally, a second and / or further sensing device can also be arranged on the second circular segment.

[0017] According to a preferred embodiment of a position and / or distance measuring system with multiple tracks, the first track defines a first module and the second track defines a second module. Preferably, the lowest common multiple of the first and second modules is an odd multiple of the first and / or second modules. Alternatively or additionally, it can be provided that the second module is 2% to 50%, in particular 3% to 30%, preferably in the range 5% to 95%, particularly preferably in the range 7% to 15% larger than the first module. The module preferably designates a periodically repeating pattern of the track of constant size, for example a distribution of equally wide and / or similar measuring increments.For example, the first track and the second track can differ in the manner of a vernier scale, wherein, for example, the first module of the first track has ten different, equally sized and evenly distributed first measuring increments along a unit length in the main extension direction, and wherein the second module of the second track has nine different, equally sized and evenly distributed second measuring increments along the same unit length in the main extension direction. In this preferred embodiment, it can be provided, in particular, that the sensing units and tracks operate using the same measuring principle. Such a measuring device can easily achieve a particularly high combined measuring resolution. In particular, a precise measuring resolution can be realized for particularly long strokes.

[0018] In a preferred development of a position and / or distance measuring system, the actuating rod has at least one coded third track aligned along the main extension direction. The third track is preferably provided in addition to the first track and in addition to the second track. In addition, the sleeve carries at least one third sensing unit, wherein the third sensing unit is designed and configured for preferably contactless detection of the third track. The third track and the third sensing device can operate according to the same measuring principle as the second and / or first track-sensing device pairing. In particular, the third track defines a third module, which differs from the first module and the second module. Preferably, the lowest common multiple of the third and first modules is an odd multiple of the first and / or third modules.Alternatively or additionally, the lowest common multiple of the third and second modules is an odd multiple of the second and / or third modules. Alternatively or additionally, the third module can be 2% to 50%, in particular 3% to 30%, preferably in the range 5% to 95%, particularly preferably in the range 7% to 15% larger than the second module. Surprisingly, it has been shown that when using exactly three track-sensing unit pairs, particularly high precision position and / or distance measurement over long strokes can be achieved in very small installation space. If the number of tracks is increased further, in particular when using the same measuring principle for the different tracks, not only does the required installation space increase, but so does the risk of incorrect measurements due to interactions between the multiple sensing units.

[0019] In an expedient embodiment of a position and / or distance measuring system that can be combined with the aforementioned, the at least one track is magnetically encoded, and the sensing device comprises a magnetic sensor, in particular a magnetoresistive sensor, such as a GMR sensor, AMR sensor or TMR sensor, for example a GLM sensor. In particular, the plurality of tracks are magnetically encoded. In particular, the plurality of sensing devices each comprise a magnetic sensor. It has proven particularly expedient in combination with a magnetic sensor if the valve rod comprises or consists of a magnetically conductive material (e.g. stainless steel 1.4104).The magnetic sensor system has, in particular, a period length (pitch) of at least 1 mm, in particular at least 2 mm or at least 3 mm, preferably at least 5 mm, particularly preferably at least 10 mm, whereby the sensor system can determine a stroke that is less than or equal to the period length with absolute certainty. Control valves of this type often have a stroke that is a multiple of the period length.

[0020] Alternatively or additionally, in an embodiment of a position and / or distance measuring system that can be combined with the above, it is provided that the at least one track, in particular the plurality of tracks, is optically coded and that the sensing device comprises an optical sensor. In particular, the plurality of sensing devices each comprise an optical sensor. Alternatively, a combined sensing device with an optical sensor, such as a CCD sensor, can be provided in functional union for detecting multiple tracks.

[0021] The at least one track, in particular the plurality of tracks, are preferably arranged at least predominantly or completely in a half of the actuating rod facing the actuator or facing away from the actuator.

[0022] In one conceivable embodiment of a position and / or distance measuring system, the at least one track comprises a plurality of projections on the actuating rod. The track can be implemented, for example, as a toothed structure or the like that protrudes radially from the actuating rod. The track can comprise a plurality of projections that are preferably arranged parallel to one another in the main extension direction and whose projection extent is oriented radially to the main extension direction of the actuating rod. The projections can preferably be annular or circular. Alternatively, the projections can be annular or circular segment-shaped. The projections can provide coding through their shape, thickness, or spacing. The track can, for example, be arranged in the form of such projections along the actuating rod, covering a measuring range that corresponds at least to the stroke of the control valve.It can be provided that the track does not move into the valve housing or the actuator during operation. The shape, size, and spacing of the projections, in particular transverse grooves, in the main extension direction, in particular the uniform spacing (the module) of the projections in the main extension direction, is preferably matched to the cooperating sensing unit, in particular a period length of the, for example, magnetic sensing unit.

[0023] In a preferred embodiment of a position and / or distance measuring system, the at least one track comprises a plurality of recesses in the actuating rod. The track can be implemented, for example, as a toothed structure or the like incorporated into the actuating rod. The track can comprise a plurality of transverse grooves arranged preferably parallel to one another in the main direction of extent, the groove extension of which is oriented transversely, in particular perpendicularly, to the main direction of extent of the actuating rod. Recesses can be produced, for example, by a machining process, such as turning or milling, or a forming process, such as a stamping process or a rolling process. The track can, for example, be arranged in the form of such recesses along the actuating rod, covering a measuring range which corresponds at least to the stroke of the control valve.The shape, size, and spacing of the recesses, in particular transverse grooves, in the main extension direction, in particular the uniform spacing (the module) of the recesses in the main extension direction, is preferably matched to the sensing unit cooperating therewith, in particular a period length of the, for example, magnetic sensing unit.

[0024] In a preferred development of a position and / or distance measuring system, at least one track of which comprises recesses, the recesses are filled with a material that is contrasting and / or transparent to the sensing device. Due to different, in particular magnetic, properties of the materials of the actuating rod and filling, the tracks can be read precisely. According to a preferred variant, the actuating rod, in which the recesses are formed, is formed from or with a material that interacts with the sensing device and from which the filling material differs. In this case, it can preferably be provided that the filling material is transparent to the sensing device. Alternatively, the filling material can interact differently or more strongly with the sensing device than the material of the actuating rod.For example, recesses in the tracks can be filled with non-magnetizable materials, such as flame spraying, chrome plating, or overmolding with plastic. Particularly in combination with the use of an optical sensing unit, the recesses can be filled with optically transparent materials, particularly within a specific optical spectrum, such as a transparent plastic such as epoxy or synthetic resin, PC (polycarbonate), or PMMA (Plexiglas), and / or thermoplastically overmolded.

[0025] According to an expedient development of a position and / or displacement measuring system with at least one track comprising recesses, the actuating rod has a smooth, preferably rotationally symmetrical, circumferential surface in the region of this track (measuring area). The circumferential surface is preferably surrounded by a coating that is at least partially or completely transparent to the sensing device.

[0026] For example, an actuating rod can be provided with at least one track, in particular with filled recesses, with a circular, smooth circumferential surface. Optionally, the tracks are not visually visible on such a shaft. Providing a smooth circumferential surface, in particular by filling and smoothing recesses, has the advantage that the part of the shaft with the code tracks can penetrate into the control valve housing with the sealing packings or into the actuator without the depressions of the code tracks impairing or even damaging the seals on the housing of the control valve and / or the actuator. The inner length of a yoke between the actuator and the valve housing is then not necessarily set to a minimum size corresponding to the stroke length to be measured, but can be dimensioned smaller. This means that even very short yoke lengths can be used to measure large strokes with high precision.At the same time, the advantage remains that the stroke sensor can be located outside the process fluid on the yoke between the valve body and the actuator.

[0027] In a further embodiment of a position and / or displacement measuring system, which can be combined with the aforementioned, the measuring device has a mounting flange for fastening the measuring device to the control valve, in particular the yoke. The recess, in particular the sleeve with the recess defined by it, is rotatably connected to the mounting flange. In particular, the recess, preferably the sleeve, is connected to the control valve by means of a plain bearing. It can be provided that the plain bearing has a loose state in which the recess, preferably the sleeve and / or the at least one sensing device, is rotationally movable with respect to the stroke axis of the control valve and is held stationary in the axial and / or radial direction by the plain bearing.Preferably, the position and / or distance measuring system is designed and configured such that, in the loose state, the measuring device is aligned in a rotationally fixed manner relative to the actuating rod with respect to the stroke axis by the adjusting device, in particular the rotation lock. In the loose state, a rotation of the actuating rod with respect to the stroke axis can be accompanied by a corresponding rotation of the measuring device with respect to the stroke axis, such that the actuating rod is oriented with minimal rotational angle offset or without rotational angle offset with respect to the measuring device. The plain bearing can have a fixed state in which it is fixed to the control valve, in particular the yoke and / or the control valve housing, in a rotationally fixed manner with respect to the stroke axis. In the fixed state, the adjusting device, in particular the rotation lock, can urge the actuating rod into an orientation oriented with respect to the measuring device with minimal rotational angle offset or without rotational angle offset.For example, it can be provided that for the assembly of the position and / or distance measuring system, pre-assembly first takes place in the loose state, wherein the measuring device is fixed axially to the control valve while the adjusting device adjusts the orientation of the actuating rod to the measuring device. If the adjusting device acts by means of magnetic force, the assembler experiences noticeable haptic confirmation of the oriented alignment of the actuating rod with the at least one track fixed thereto relative to the measuring device. Then, during final assembly, the measuring device can be fixed rotationally and radially to the control valve so that a defined annular gap remains in the recess between the actuating rod and the measuring device, preferably in the radial direction.

[0028] The invention also relates to a control valve for a process fluid flow in a process plant, such as a power plant, a chemical plant, a food processing plant, or the like. The control valve according to the invention comprises a position and / or displacement measuring system designed as described above. In particular, the measuring axis of the measuring device corresponds to the stroke axis of the control valve. Preferably, the measuring axis is parallel, particularly preferably collinear, to the stroke axis.

[0029] Furthermore, the control valve comprises a valve housing with an actuator arranged therein, which is carried by the control rod and an actuator for actuating the control rod.

[0030] It may be preferred that the position and / or distance measuring system is matched to the valve housing in such a way that the at least one track is always arranged outside the valve housing. The track can preferably be arranged at least predominantly or completely in a half of the control rod that is to be or is facing the actuator. For this purpose, the control valve is preferably spaced from the at least one track on the control rod. In particular, the track can be arranged, preferably formed, at a distance from the actuator in or on the control rod that is at least as large as or greater than the stroke. In addition, it can optionally be provided that the position and / or distance measuring system is matched to the control actuator in such a way that the at least one track is always arranged outside the control actuator.For many process fluids, specific requirements are defined by the areas of the control rod that may come into contact with the process fluid. For some process fluids, it may therefore be advantageous to position the track(s) in a section of the control rod that never moves into the valve body or through its rod seal.

[0031] According to a particular embodiment, the position and / or displacement measuring system is adapted to the actuator such that at least one track is arranged within the actuator in at least one open and / or closed position of the actuator. The actuator can preferably be implemented as a single- or double-acting hydraulic or, preferably, pneumatic actuator.

[0032] In a preferred development of the control valve, the at least one track preferably always projects into the control actuator and the measuring device is arranged within the control actuator. The control actuator can preferably be implemented as a single- or double-acting hydraulic or, preferably, pneumatic actuator. In a pneumatic or hydraulic actuator, the at least one hydraulic or pneumatic working chamber is pneumatically and / or hydraulically separated from the other actuator chamber, which can contain a return spring and / or be designed as a second hydraulic or pneumatic working chamber, by a membrane or other separating element. The measuring device is arranged in the control actuator in a collision-free manner with respect to the separating element and / or the return spring, i.e. outside the working range of the separating element and / or the return spring.In this way, it is prevented that, for example, the diaphragm or spring moves against the measuring device when the control valve is closed.

[0033] In a preferred embodiment, the control valve further comprises a yoke which fastens the control actuator to the valve housing and in which the control rod is accommodated for linear movement. Optionally, it can be provided that the control rod is movable along a linear stroke which is greater than the height of the yoke between the valve housing and the control actuator. For example, the stroke can have a linear length of at least 5 mm, in particular at least 10 mm or at least 50 mm. The length of the stroke is in particular between 5 mm and 500 mm, preferably between 7.5 mm and 120 mm. The stroke is preferably greater than the clearly resolvable period length of the at least one sensing device, in particular at least twice as large, preferably at least five times as large, particularly preferably at least ten times as large.

[0034] The yoke and the actuating actuator and / or the valve housing are preferably dimensioned with respect to the stroke and the actuating rod in such a way that, along the stroke, the track on the actuating rod is immersed in the actuating actuator or in the valve housing or in both the actuating actuator and the valve housing. Process fluid

[0035] The process fluid generally refers to a fluid to be processed in the process plant. The process fluid can be gaseous, liquid, or a multiphase mixture, at least in part, in the process plant. In particular, the process fluid can be or comprise water. The process fluid can be an at least approximately Newtonian fluid. Alternatively, the process fluid can be a non-Newtonian fluid, for example, a rheopexic or thixotropic fluid. Process fluid flow

[0036] Process fluid flow refers to the flow of the process fluid in the process plant, at least in sections. A process fluid flow can be characterized at least locally, at a point in the process plant, in particular at a control valve, based on its fluid dynamic flow properties, such as a flow rate or flow volume, a process fluid temperature, a process fluid pressure, or the like. control valve

[0037] A control valve generally refers to a valve in a process plant for adjusting a process fluid flow within the process plant. For example, a control valve can be implemented as an on / off valve that has a predefined closed position and a predefined open position, between which the on / off valve can switch during operation. Alternatively or additionally, the control valve can be designed and configured to adjust flow characteristics of the process fluid flow within a predefined adjustment range. For example, the control valve can be designed and configured to adjust a flow characteristic, such as a flow rate or flow volume through the control valve, a process fluid temperature upstream and / or downstream of the control valve, a process fluid pressure upstream and / or downstream of the control valve, a process fluid pressure difference across the control valve, or the like.In particular, the control valve can be designed and configured to continuously or discretely adjust a flow characteristic of the process fluid flow within a predefined adjustment range. A control valve generally comprises a control valve housing, an actuator, a control actuator, and control and / or regulating electronics. The control valve housing has at least one inlet for the process fluid and at least one outlet for the process fluid, as well as a passage with an opening cross-section adjustable by means of the actuator between the inlet and the outlet. The control actuator of the control valve is designed and configured to position the actuator of the control valve within the control valve housing relative to the passage in order to adjust at least one flow characteristic through the relative position of the actuator relative to the passage.For example, the actuator can be designed to urge the actuator into a closed position that closes the passage, to urge the actuator into an open position that completely releases the passage, and / or to cause the actuator to assume an intermediate position among a plurality of intermediate positions with different, defined opening cross-sections between the actuator and the passage. The actuator can be implemented, for example, as a pneumatic actuator, particularly a single-acting or double-acting actuator, a hydraulic actuator, and / or an electromagnetic actuator, particularly with or without a spring return. The actuator is preferably mechanically connected to the actuator by means of an actuating rod.The control and / or regulation electronics of the control valve are designed and configured to actuate the control actuator in order to effect a desired effect of the control valve on a flow characteristic of the process fluid flow. The control and / or regulation electronics can take into account at least one setpoint specification and / or at least one actual value specification with regard to at least one flow characteristic of the process fluid flow in order to provide an actuation signal to the control actuator. The control valve is preferably designed and configured for a process fluid flow, in particular a water flow, of up to at least 1 L / h, whereby this refers to the flow rate of the process fluid flow through the control valve when the control valve is fully open, i.e., in the open position of the control valve.In particular, the control valve is designed and configured for a process fluid flow of up to at least 5 L / h, up to at least 10 L / h, up to at least 50 L / h, up to at least 100 L / h, up to at least 500 L / h, or up to at least 1,000 L / h. It should be understood that this refers to the process fluid flow under nominal operating conditions. In an intermediate position of the control valve, a correspondingly lower process fluid flow can be set. In a closed position, the process fluid flow can be zero or nearly zero. In the closed position, the control valve allows process fluid flow from the inlet to the outlet. Actuator (reciprocating piston)

[0038] An actuator generally refers to a component of the control valve that is movable relative to the control valve housing, in particular a passageway in the control valve. The process fluid flow can be adjusted using the actuator. Actuators can, for example, be designed and configured to assume at least two different relative positions within a control valve housing in order to set at least two different process fluid flows, in particular at least one open position in which the actuator permits a maximum process fluid flow through the control valve, and at least one closed position or closed position in which the actuator permits no process fluid flow, almost no process fluid flow, or a predetermined minimum process fluid flow through the control valve.The actuator can be designed and configured to assume a plurality of relative positions with respect to the control valve housing in order to set a corresponding plurality of different process fluid flow rates. The various relative positions with process fluid flow rates and the open position can be referred to as flow positions. In a control valve designed as a globe valve, the control valve member can, for example, be conical or implemented as a reciprocating piston. A reciprocating piston generally comprises a cylindrical piston body and a control rod that is detachably or permanently connected to the body. The piston body of the actuator can have a rotationally symmetrical or mirror-symmetrical shape with respect to a control axis.The piston body and the actuating rod are preferably concentric, in particular coaxial, with each other, wherein the main extension direction of the actuating rod preferably corresponds to the translational actuating direction of the valve member, which can also be referred to as the stroke direction. The piston body can have a conical cross-section. Preferably, a piston body has a truncated cone-shaped or conical taper on the side opposite the actuating rod, wherein the taper in particular defines a counter-sealing surface. The piston body can have a U-shaped or H-shaped cross-section. Reciprocating pistons with a U-shaped or H-shaped cross-section can be designed and configured to interact with a corresponding, in particular shape-complementary, hollow cylindrical valve cage.Conical, partially spherical or similar piston bodies can be designed and arranged to interact with a corresponding, in particular complementary annular, preferably circular, valve seat at the passage of the control valve housing.

[0039] Further properties, advantages and features of the invention will become clear from the following description of preferred embodiments of the invention with reference to the accompanying drawings, in which: Figure 1 shows a sectional view of a control valve according to the invention with a path and / or position measuring system according to the invention; Figure 2 shows another sectional view of the control valve with the measuring system according to Figure 1; Figure 3 shows a sectional view of a path and / or position measuring system according to the invention; Figure 4 shows a perspective view of an adjusting rod for a measuring system according to the invention; Figure 5 shows a perspective view of a sleeve for a measuring system according to the invention; and Figure 6 shows another perspective view of the adjusting rod according to Figure 4 .

[0040] In the following description of preferred embodiments with reference to the figures, the same or similar reference numerals are used for the same or similar components of different embodiments.

[0041] A displacement and / or position measuring system according to the invention (short: measuring system) is generally designated by reference numeral 1. A control valve according to the invention is generally designated by reference numeral 100.

[0042] To simplify readability, the following description of preferred embodiments of the invention describes a magnetic measuring system with a magnetoresistive sensing device, which is implemented as a GLM sensor system. Those skilled in the art will understand that other measuring principles, such as optical measuring principles, may also be considered within the scope of the invention.

[0043] In the following description of preferred embodiments based on the figures, only those control valves are shown whose valve member 120 is frustoconical. It should be understood that an analysis arrangement according to the invention may alternatively comprise a different type of actuator (not shown in detail).

[0044] The operational flow direction of a process fluid in the control valve 100 shown below in the various designs of different analysis arrangements can be set optionally from "right" to "left" (flow-to-close; abbreviated: FTC) or alternatively from "left" to "right" (flow-to-open; abbreviated: FTO). A control valve can be specifically designed and configured for the flow-to-open and / or the flow-to-close flow direction. For the sake of easy readability of the application, the flow-to-open flow direction, from "left" to "right," is assumed below as an example, and in this sense, terms related to the flow direction, such as "inlet" and "outlet," of the control valve are used.

[0045] The Figures 1 and 2show an exemplary embodiment of a control valve 100 with a position and / or displacement measuring system 1. The control valve 100 has a reciprocating piston 120, which is translationally movable in the control valve housing 110 according to a stroke axis H. To simplify readability, the stroke axis H of the control valve 100 is shown in the figures corresponding to the main extension direction of the control rod 3 and the measuring axis of the measuring device 5. In the figures, the control rod 3 is shown ideally collinear with respect to the measuring device 5, without any tilting, inclination, and / or rotation angle offset.

[0046] The actuator 130, for example a pneumatic actuator, of the control valve 100 is indirectly attached to the cover section 115 of the control valve housing by means of a yoke 140, which can be designed, for example, as an open or closed lantern. The actuator 130 is connected to the reciprocating piston 120 by means of the actuating rod 3 in order to move the reciprocating piston 120 into an operating position, to hold it in an operating position, and / or to communicate an actuation to the reciprocating piston 120. The operating position of the actuator 120 can be adjusted along the stroke h. The actuator 130 is connected to control and / or regulating electronics (not shown) for signal transmission. The control electronics are designed and configured to provide a control signal to the actuating actuator 130 to cause the actuating actuator 130 to communicate a specific actuating action to the reciprocating piston 120, to impart actuating movement and / or to provide actuating force.Position and / or displacement measuring system 1 is connected to the control electronics via signal transmission. The measuring system provides the control electronics with an actual position and / or displacement measurement value.

[0047] In the interior 111 of the control valve housing 110, a process fluid can be in an open position, such as the open position according to Figure 2 , flow from the inlet 121 through the passage 125 to the outlet 129. The process fluid-carrying interior 111 of the control valve housing 110 is delimited at the inlet 121 and outlet 129 of the control valve 100 by a respective housing channel wall. The control rod 3 is led out of the interior 111 of the valve housing 110 through an outlet opening 116. In the area of ​​the outlet opening 116, a sealing packing 117 is provided, which completely surrounds the control rod 3 and, together with the control rod 3, closes the outlet opening 116. In the closed position according to Figure 1A sealing surface 123 of the valve housing 101 cooperates with a counter-sealing surface of the actuating piston 130 to seal the control valve 100 at the passage 125 in a process-fluid-tight manner. In the illustrated embodiment, the sealing surface 123 is formed on a valve seat 103. The valve seat 103 forms part of the valve housing 110.

[0048] With the help of the control valve 100, the process fluid flow can be adjusted, for example, depending on an opening width between the control piston 120 and the valve seat 103. In the open position, the maximum flow rate of process fluid through the control valve 100 is generally at least 1 L / h. The maximum flow rate of the control valve 100 can be defined by the operational flow properties, for example the pressure, viscosity, temperature, etc., of the process fluid flow at the inlet 121 and / or at the outlet 129, the geometry of the control valve housing 110 and the opening width in the open position. In the closed position, the flow of process fluid through the control valve 100 is generally 0 L / h or almost 0 L / h. The control valve 100 is designed and configured to assume one or more intermediate positions along the stroke h and to set a process fluid flow below the maximum flow rate.Control and / or regulation electronics may be provided for this purpose.

[0049] The measuring range b of the position and / or distance measuring system 1 corresponds at least to the length of the stroke h, so that a position and / or distance measurement can be carried out along the entire stroke h by means of the measuring system 1. As can be seen from the Figures 1 and 2 As can be seen, the adjustable stroke h of the control valve 100 is greater than the clear yoke width j. The measuring range b corresponds to the axial length of the area of ​​the control rod 3 covered by the at least one coded track 33, 34. In the Figure 1 and 2In the end positions of the actuator 120 shown, the measuring range b defined by the tracks 33, 34 on the actuating rod 3 is immersed in the volume of the control valve housing 110 or the actuator 130. In an intermediate position of the actuator 120 (not shown in detail), the measuring range b extends completely beyond the clear yoke width j, both into the volume of the actuator 130 on the one hand and into the volume of the control valve housing 110 on the other. The part of the measuring range b that is located within the actuator 130 can be referred to as the actuator-side immersion depth s. The part of the measuring range b that is located within the control valve housing 110 can be referred to as the valve-side immersion depth v.

[0050] The measuring device 5 is attached to the yoke 140 and thus to the control valve 100 by means of a mounting flange 7. The mounting flange 7 holds the measuring device 1 stationary in an axial direction corresponding to the stroke axis H and the main extension direction.

[0051] A sliding bearing 71 can, in a loose state, permit rotation of the measuring device 5 about the stroke axis H, in order to easily enable a predetermined orientation of the actuating rod 3 with respect to the measuring device 5 with minimal rotational angle offset or free of any rotational angle offset. Additionally or alternatively, a radial annular gap 73 can be set between the actuating rod 3 and the measuring device 5 using the mounting flange 7. By providing the annular gap 73, the actuating rod 3 is held and guided in a contact-free manner with respect to the measuring device 5. The annular gap 73 preferably extends completely around the actuating rod 3.

[0052] For assembly, the measuring device 5 is aligned according to the tracks 33, 34 before any fixation using the mounting flange 7. In doing so, the sensing devices 53, 54 are positioned facing the tracks 33, 34. This can be achieved, for example, using a directional structure on the actuating rod, such as a longitudinal recess, and an adjustment device in the form of a raised portion on the measuring device 5 that is complementary in shape to the longitudinal recess. Alternatively, the directional structure 31 and the permanent magnet 51 can be used, as shown. After the position measuring device 5 has been adjusted, the position measuring system can be fixed to the control valve using the mounting flange 7. In particular, if the actuating rod 3 is secured against twisting, the measuring device 5 can be connected to the yoke in a rotationally fixed manner using the mounting flange 7.If the measuring device 5 has an anti-rotation device (not shown in detail), for example in the form of a tongue and groove connection, in particular between the measuring device 5 and the actuating rod 3, it may be expedient to design the anti-rotation device with play to prevent jamming. For actuating rods 3 that are not secured against rotation relative to the valve housing, it can be provided that the measuring device 5 is held on the valve housing so that it can rotate with respect to the stroke axis H and is configured to adapt to a rotational movement of the actuating rod 3 in order to maintain the most precise alignment possible of the sensing devices 53, 54 relative to the tracks 33, 34.The measuring device 5 can be held in a rotationally fixed manner relative to the adjusting rod by means of a rotation lock, for example the aforementioned longitudinal recess in the adjusting rod 3 with a nose of the measuring device 5 engaging therein in a complementary shape, or an adjusting device, such as the illustrated, mutually coordinated permanent magnets 51 and the directional structure 31.

[0053] According to an alternative embodiment (not shown in detail), it is conceivable that the track 33 or tracks 33, 34 are arranged differently than in Figure 1 shown, never penetrates into the interior of the valve housing 110, preferably including the area occupied by the sealing packing 117.

[0054] Alternatively or additionally, according to an embodiment (not shown in detail), the measuring device can be arranged within the preferably pneumatic actuator 130. Referring to Figure 2The measuring device could be located within the chamber near the valve housing, for example as in the Figures 1 or 2 shown in the pneumatic chamber of actuator 130. The actuator is preferably designed, for example, by means of a stop, such that the separating element between the actuator chambers, as well as any return springs, do not collide with the measuring device inside the actuator. Such a design can be optimized with regard to the compactness of the control valve.

[0055] Figure 3 shows a cross-sectional view of an embodiment of the position and / or measuring system 1 according to the invention with two coded tracks 33, 34. The Figures 4 and 5 show the individual components adjusting rod 3 and measuring device 5 of the Figure 3illustrated measuring system 1. It will be clear to a person skilled in the art that, as an alternative to the variant shown, a measuring system 1 can have just one track, three tracks, or more tracks. The number of sensing devices 53, 54 corresponds to the number of tracks 33, 34. Preferably, the number of sensing devices 53, 54, as shown, is the same as the number of tracks 33, 34. Alternatively, in an optical measuring system, for example, not shown in more detail, a single sensing device can be provided for multiple tracks. It is conceivable for multiple, in particular magnetic, sensing devices to be arranged offset from one another in the main extension direction. Alternatively or additionally, it is conceivable for multiple tracks on the actuating rod 3 to be arranged offset in the main extension direction, for example in alignment one behind the other, wherein in particular these multiple tracks have different modules, in particular different modules or periods.For example, an upper track may have a larger period than a lower track.

[0056] The adjusting rod 3 has a directional structure 31 for orienting the adjusting rod 3 relative to the measuring device 5. In the Figure 4 In the exemplary embodiment shown, the directional structure 31, as well as the track 33, are realized in one piece with the adjusting rod 3. The directional structure 31 is formed by a rib 41, which extends corresponding to the main extension direction of the adjusting rod 3. In the circumferential direction of the adjusting rod 3, the rib 41 is delimited on both sides by a radial recess 43.

[0057] The measuring device 5 comprises a permanent magnet 51, which is designed and configured to cooperate with the directional structure 31 in order to orient the actuating rod 3 relative to the measuring device 5. In the embodiment shown here, an adjustment device is realized by the directional structure 31 and the permanent magnet 51, by means of which the actuating rod 3 is adjusted free of any rotational angle offset relative to the measuring device 5 with respect to the measuring axis. The adjustment device can additionally or alternatively be designed, for example by means of a second permanent magnet 51 offset in the axial direction, to orient the actuating rod 3 free of any tilt and / or inclination angle with respect to the measuring device 5. The notches 43 and the rib 41 preferably extend along the main extension direction of the actuating rod 31 at least over a large part of the measuring range b.The directional structure 31 is formed on the adjusting rod 3, parallel to the first track 33 and / or the second track 34. Like the rest of the adjusting rod 3, the directional structure 31 consists of a material that interacts with the sensing devices 53, 54, for example, a magnetic or magnetizable material, to which the directional magnet 51 acts with a magnetic force of attraction. The magnetic force of attraction or directional force provided by the directional magnet 51 acts particularly strongly on the convex rib 41 and particularly weakly in the area of ​​the concave notches 43. When the measuring system 1 is mounted, the adjusting rod 3 snaps into place relative to the measuring device 5 in the predetermined orientation.Since the directional magnet 51 acts particularly strongly on the rib 51 and particularly weakly on the notches 43 surrounding the rib 51, the adjusting device prevents the control rod from leaving the predetermined orientation during operation of the control valve 100, for example as a result of rotational forces on the valve member 120.

[0058] As in Figure 3As shown, the actuating rod 3 is surrounded by a coating 40, which forms the cylindrical circumferential surface. The circumferential surface describes a circular cross-section. Preferably, the circumferential surface is smooth. Particularly preferably, the circumferential surface is smooth such that the surface accuracy essentially corresponds to the surface accuracy of a conventional actuating rod without traces and / or that a secure and leak-free seal can be realized in the region of the outlet opening 116 of the valve housing 110, for example by means of a sealing packing 117. The coating 40 is formed from a material that is transparent to the sensing device 53, 54, for example, a non-magnetizable material, for example a plastic material. As shown in the Figures 1 and 2As indicated by dashed lines of the tracks 33, 34 and the directional structure 31, the coating 40 may consist of an optically non-transparent material, so that the magnetically encoded tracks 33, 34 and the directional structure 31 are not optically visible. Figures 4 and 6the coating is not shown. The coating can functionally fill the recesses. Alternatively, it can be provided that only recesses and / or notches in the actuating rod 3 are filled with a filling material (not shown in more detail). The filling material can be transparent or contrasting for the sensing device. For example, in a design with a filling material that differs from the material of the actuating rod, as well as from the material of any sensor-transparent coating or other sheathing that may be present, it can be provided that the filling material and the actuating rod are contrasting for the sensing device, wherein, for example, the actuating rod can be non-magnetizable and the filling material can be magnetic or magnetizable.

[0059] In Figure 5The measuring device 5 is shown without the adjusting rod 3. The measuring device 5 has a recess 50 for receiving the adjusting rod 3. The recess 50 is preferably shaped correspondingly, in particular complementarily, to the cross section of the adjusting rod 3. In particular, the recess 50 and the adjusting rod 3 are matched to one another in such a way that the adjusting rod 3 is arranged in the receptacle 50 of the measuring device 5, forming a narrow annular gap 73 relative to the sleeve 60, as shown in Figure 3 shown.

[0060] The hollow cylindrical sleeve 60 has a part-circular cross-section, which, for example, Figure 5 shown is approximately 2 / 3 circular, or as in Figure 3 shown in a U-shape around the adjusting rod 3. As shown in the Figures 1 and 2As can be seen, the plain bearing 71 can be fixed to the sleeve 60. With respect to the stroke axis H, the sleeve 60, in the assembled state, extends over a large part of the clear width j of the yoke 140. The axial height of the sleeve 60 can, for example, be in the range of 50% to 80% of the clear yoke width j. The sleeve 60 has a partially circumferential opening 65 for inserting the adjusting rod 3. The opening 65 extends in the radial direction from the receptacle 5 for the adjusting rod transversely through the sleeve 60.

[0061] The sleeve 60 is composed of several circular sections 61, 62. The first circular section 61 can have a greater circumferential extent than the second circular section 62. The first sensing device 53 and optionally the second sensing device 54 are attached to the first circular section 61. The directional magnet 51 is attached to the second circular section 62. The sleeve 60 can be one-piece, with the circular sections 61, 62 being connected by a flexure joint 63. In the circumferential direction, the first circular section 61 extends over approximately 135° to 180°, and the second circular section extends over approximately 90° to 135°. In the circumferential direction, between the circular sections 61, 62, the flexure joint 63 is provided on the one hand, and the receiving opening 65 is provided on the other. The sensing devices 53 and 54 are attached to the first circular section 61, offset by 90°.In the embodiment shown here, both the first sensing device 53 for detecting the first track 33 and the second sensing device 54 for detecting the second track 34 are designed as magnetoresistive sensors, for example, as a GLM sensor. Correspondingly, two tracks 33, 34 offset by 90° are provided on the actuating rod 3, each extending in the main direction of extension of the actuating rod 3, as shown in FIG. Figure 6 shows.

[0062] Figure 6shows two similar tracks 33, 34 of the actuating rod 3, which are each implemented by a tooth structure. The tooth structure is formed by recesses in the form of parallel transverse grooves that are introduced into the actuating rod 3. The first track 33 and the second track 34 differ in the respective modulus m 1 and m 2 of the number structures. The two tooth structures each have a constant modulus m 1 , m 2 , which defines the period of the webs and recesses that alternate with one another in the main direction of extension of the actuating rod 3. For example, the second modulus m 2 can be 10% larger than the first modulus m 1 , resulting in a vernier-like structure. The respective first or second modulus m 1 or m 2 is less than or equal to the period length of the respectively assigned sensing device. In this way, an absolute position measurement of high precision can be implemented using simple means.

[0063] It is conceivable that a third track with a third module is provided on the actuating rod 3, and a third sensing device corresponding to the third track is provided on the measuring device 5 in order to achieve an even higher measurement resolution (not shown). The width of the tracks 33, 34 in the main extension direction of the actuating rod 3 defines the measuring range b of the position and / or displacement measuring system 1. The high precision of the measuring system 1 is achieved thanks to the precise orientation of the actuating rod 3 in relation to the measuring device 5 or of the tracks relative to the sensing devices assigned to them by means of the adjustment device.

[0064] The features disclosed in the above description, figures and claims may be important both individually and in any combination for the realization of the invention in the various embodiments. List of reference symbols

[0065] 1Position and / or displacement measuring system 3Actuating rod 5Measuring device 7Mounting flange 31Directional structure 33, 34Track 41Rib 43Depression 50Recess 51Permanent magnet 53, 54Sensing device 60Sleeve 61First circular section 62Second circular section 63Solid-state joint 65Receiving opening 71Plain bearing 73Annular gap 100Control valve 110Valve housing 111Inner 115Cover section 116Outlet opening 117Sealing packing 120Valve element 121Inlet 125Passage 129Outlet 130Actuator 140Yoke δRotational offset bMeasuring range hStroke path jClear yoke width m 1 first module m 2 second module sActuator-side immersion depth vValve-side Immersion depth HLifting axis

Claims

1. Position and / or displacement measuring system (1) for a control valve (100) for a process fluid flow of a process engineering plant, such as a power plant, a chemical plant, a food processing plant or the like, comprising: a linearly movable control rod (3) with at least one main extension direction and at least one coded track (33, 34) aligned along the main extension direction, a measuring device (5) with at least one preferably partially circular recess (50) for receiving the control rod (3) in a linearly movable manner and at least one sensing unit (53, 54) arranged at the recess (50), which is designed and configured for preferably contact-free detection of the at least one track (33, 34), wherein the position and / or displacement measuring system comprises an adjusting device arranged in the region of the recess (50) for orienting the control rod (3) relative to the measuring device (5), characterized in that the adjusting device orients the control rod (3) relative to the recess (50) in a contact-free manner, preferably magnetically.

2. Position and / or displacement measuring system (1) according to claim 1, characterized in that the adjusting device is designed and configured to orient the control rod (3) relative to the measuring device (5) with a rotational offset (δ) with respect to the main extension direction of not more than ±10°, in particular not more than ±7°, preferably not more than ±4°, wherein in particular the adjusting device comprises an in particular form-fitting anti-rotation device.

3. Position and / or displacement measuring system (1) according to claim 1 or 2, characterized in that the recess (50) has a permanent magnet (51) and the control rod (3) has a magnetizable or magnetic directional structure (31).

4. Position and / or displacement measuring system (1) according to any one of the preceding claims, characterized in that the measuring device (5) comprises an in particular partially circular sleeve (60), which defines the recess (50) and carries the at least one sensing unit (53, 54).

5. Position and / or displacement measuring system (1) according to claim 4, characterized in that the control rod (3) has at least one coded second track aligned along the main extension direction, wherein preferably the second track is arranged offset relative to the first track in the circumferential direction, for example offset by 60° or 90°, and in that the sleeve carries at least one second sensing unit (54), wherein the second sensing unit (54) is designed and configured for preferably contact-free detection of the second track, wherein preferably the second sensing unit (54) is arranged offset relative to the first sensing unit in the circumferential direction, for example offset by 60° or 90°, wherein preferably the offset of the sensing units (53, 54) corresponds to the offset of the tracks (33, 34).

6. Position and / or displacement measuring system (1) according to claim 4 or 5, characterized in that the sleeve (60) has a first circular section (61), at which the at least one sensing unit (53) and optionally the second and / or a further sensing unit (54) are arranged, and in that the sleeve (60) has at least one second circular section (62), which is movably connected to the first circular section (61), preferably by means of a flexure bearing (63), wherein the first circular section (61) has a partially circumferential opening (65) for inserting the control rod (3) and / or wherein the second circular section (62) is arranged in the radial direction at least in sections diametrically opposite the first circular section (61), wherein in particular the adjusting device is arranged at the second circular section (62).

7. Position and / or displacement measuring system (1) according to any one of claims 5 or 6, characterized in that the first track (33) defines a first module (m1) and in that the second track (34) defines a second module (m2), wherein preferably the smallest common multiple of the first and of the second module is an odd multiple of the first and / or second module and / or wherein the second module is 2% to 50%, in particular 3% to 30%, preferably in the range 5% to 25%, particularly preferably in the range 7% to 15%, larger than the first module.

8. Position and / or displacement measuring system (1) according to any one of claims 5 to 7, characterized in that the control rod (3) has at least one coded third track aligned along the main extension direction, and in that the sleeve carries at least one third sensing unit, wherein the third sensing unit is designed and configured for preferably contact-free detection of the third track, wherein in particular the third track defines a third module.

9. Position and / or displacement measuring system (1) according to any one of the preceding claims, characterized in that the at least one track (33, 34) is magnetically coded and in that the sensing device (53, 54) comprises a magnetic sensor system, such as an AMR sensor system, TMR sensor system or AMR sensor system, for example a GLM sensor system, and / or in that the at least one track (33, 34) is optically coded and in that the sensing device (53, 54) comprises an optical sensor system, and / or in that the at least one track (33, 34) comprises a plurality of, in particular annular or ring-segment-shaped, projections on the control rod (3).

10. Position and / or displacement measuring system (1) according to any one of claims 1 to 9, characterized in that the at least one track (33, 34) comprises a plurality of recesses in the control rod (3), wherein in particular the recesses are filled with a contrasting and / or transparent material for the sensing device (53, 54).

11. Position and / or displacement measuring system (1) according to claim 10, characterized in that the control rod (3) has a smooth, preferably rotationally symmetrical, circumferential surface in the region of the track (33, 34), wherein preferably the circumferential surface is surrounded by a coating which is at least partially or completely transparent for the sensing device (53, 54).

12. Position and / or displacement measuring system (1) according to any one of the preceding claims, characterized in that the measuring device (5) has a mounting flange (7) for fastening the measuring device (5) to the control valve (100), in particular a yoke (140), wherein the recess (50) is connected to the mounting flange (7) in a rotationally movable manner, in particular with a sliding bearing.

13. Control valve (100) for a process fluid flow of a process engineering plant, such as a power plant, a chemical plant, a food processing plant or the like, comprising: a position and / or displacement measuring system (1) according to any one of the preceding claims, a valve housing (110) with an actuator (120) arranged therein, which is carried by the control rod (3), and a control actuator (130) for actuating the control rod (3).

14. Control valve (100) according to claim 13, characterized in that the position and / or displacement measuring system (1) is matched to the valve housing (110) in such a way that the at least one track (33, 34) is always arranged outside the valve housing (110), wherein preferably the actuator (120) is arranged at a distance from the at least one track (33, 34) on the control rod (3), and / or in that the position and / or displacement measuring system (1) is matched to the control actuator (130) in such a way that the at least one track (33, 34) is arranged inside the control actuator (130) in at least one opening and / or closing position of the actuator (120), wherein in particular the at least one track (33, 34) preferably always projects into the control actuator (130) and the measuring device is arranged inside the control actuator (130).

15. Control valve (100) according to claim 13 or 14, further comprising: a yoke (140), which fastens the control actuator (130) to the valve housing (110) and in which the control rod (3) is received in a linearly movable manner; and in that the control rod (3) is movable along a linear stroke path, which is greater than the height of the yoke (140) between the valve housing (110) and the control actuator (130).