Magnetic position determination of a coolant valve needle
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- VOLKSWAGEN AG
- Filing Date
- 2024-08-01
- Publication Date
- 2026-05-20
Smart Images
Figure EP2024071937_20022025_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Magnetic position determination of a coolant valve needle
[0003] The invention relates to a needle valve with magnetic position determination of the valve needle, comprising a valve needle seat, a containment shell, a control board, an electric drive with a stator and a rotor, wherein the rotor is arranged in the containment shell, a hollow shaft with an internal thread, which is formed by the rotor or is connected to the rotor in a rotationally fixed manner, at least one bearing for the rotor, a valve needle with a valve needle tip and a valve needle shaft with an external thread, a magnetic field sensor arranged outside the containment shell in an axial direction above the hollow shaft, wherein the external thread of the valve needle shaft meshes with the internal thread of the hollow shaft and a mechanism converts the rotational movement of the hollow shaft into a linear movement of the valve needle in the axial direction, at least the rotor, the hollow shaft and the valve needle are arranged axially symmetrically with a common central longitudinal axis, characterized in thatthat the needle valve further comprises a ring magnet arranged in extension of the hollow shaft above the rotor, and a ferromagnetic metal body connected to a free end of the valve stem.
[0004] When using a needle valve, it is important that the absolute position of the valve needle, especially the valve-closed position, in which the valve needle completely closes a flow opening, can be detected very precisely and reliably. This makes it possible to detect, for example, residual dirt that prevents the needle valve from closing completely. If the needle valve does not close reliably, fluid can flow through the needle valve to a downstream unit, even when the needle valve is closed, and thereby damage or destroy the downstream unit. Especially when the needle valve is a coolant needle valve, a precise and reliable shutdown of the coolant flow is essential depending on the situation.
[0005] Various solutions are known to solve this problem. For example, EP 0383 353 A2 discloses a motor-driven valve in which a stator is provided outside a non-magnetic tubular element and a rotor is rotatably mounted in bearings within the tubular element relative to the stator. The valve comprises a mechanism with an anti-rotation means for converting the rotational movement of the rotor into a linear movement that moves a valve element toward or away from a valve needle seat. The stator comprises a plurality of magnetic poles with stator coils wound therearound and a plurality of permanent magnets with an arcuate surface attached thereto, the permanent magnets being magnetized to provide a number of pole pairs arranged at a constant pitch.The rotor includes a hub, a rim, an outer annular portion, and a number of induction teeth formed along the circumference of the outer annular portion. The total number of induction teeth is selected to differ from the total number of pole pairs of the permanent magnets by an amount equal to an even number.
[0006] US 2008 / 0092960 A1 deals with a valve system with a position sensor. The position sensor is a magnetic field sensor such as a Hall sensor that can be used to determine the axial position of a valve body relative to the valve housing. The sensor is arranged radially in the valve housing next to the axially movable valve body.
[0007] US 2014 / 0231684 A1 discloses a valve electromechanically driven by a stepper motor. The valve includes a Hall sensor mounted radially on an outer surface of the valve, which can indirectly detect whether the valve is closed or open.
[0008] US 2021 / 0175777 A1 relates to a compact control valve with an electromechanical actuator. A sensor arranged above the rotor can determine the axial position of an axially movable valve needle based on magnetic field lines. A ring magnet with axial magnetization is arranged above the rotor, and its distance from the sensor can be adjusted to detect two or three components of the magnetic field.
[0009] DE 10 2017 110 343 A1 discloses a linear actuator for a valve, comprising a drive unit comprising a stator and a rotor. The stator has several stator poles, each of which is wound with coil windings. Between the individual windings are several Hall sensors, which can be used to detect the precise position of the rotor.
[0010] DE 10 2020 104 781 A1 relates to a valve drive assembly and a valve device for controlling a fluid flow. The valve device comprises an electromechanical drive with a stator and a rotor. Furthermore, the valve unit comprises a control unit with control electronics, which may include a controller, a driver, transformers, transistors, and other passive and active sensors, such as Hall sensors.
[0011] It is the object of the invention to provide a magnetic position determination for a valve needle of a needle valve, in particular a coolant needle valve, which consists of few parts and can be manufactured inexpensively.
[0012] This object is achieved by the subject matter having the features of claim 1. The claims dependent on claim 1 relate to advantageous developments.
[0013] The invention relates to a needle valve with magnetic position determination of the valve needle, comprising a valve needle seat, a containment shell, a control board, an electric drive with a stator and a rotor, wherein the rotor is arranged in the containment shell, a hollow shaft with an internal thread, which is formed by the rotor or connected to the rotor in a rotationally fixed manner, at least one bearing for the rotor, a valve needle with a valve needle tip and a valve needle shaft with an external thread, a magnetic field sensor arranged outside the containment shell in an axial direction above the hollow shaft, and wherein the external thread of the valve needle shaft meshes with the internal thread of the hollow shaft and a mechanism converts the rotational movement of the hollow shaft into a linear movement of the valve needle in the axial direction, at least the rotor, the hollow shaft and the valve needle are arranged axially symmetrically with a common central longitudinal axis,The needle valve further comprises a ring magnet arranged above the rotor as an extension of the hollow shaft, and a ferromagnetic metal body connected to a free end of the valve stem. The needle valve may further comprise a flux-conducting sleeve arranged axially above the ring magnet and directing the magnetic field or field lines of the ring magnet's magnetic field toward the Hall sensor. The flux-conducting sleeve may extend from an end face of the ring magnet axially facing the Hall sensor to the inside of the containment shell. The flux-conducting sleeve concentrates the field lines of the ring magnet and directs them to the magnetic field sensor. The magnetic field lines run through the magnetic field sensor, through the air to the stator, and back to the magnet via the ferromagnetic metal body.
[0014] The ring magnet can be made of neodymium-iron-boron or comprise this material, for example, Nd2Fei4B. The magnetic field sensor can be arranged coaxially or eccentrically to the common central longitudinal axis.
[0015] The valve housing can be a single piece; preferably, it is multi-piece and can comprise at least one inner valve drive housing part or a containment shell, which surrounds at least the rotor and other parts of the drive, and an outer valve drive housing part, which surrounds at least the stator, the inner valve drive housing part, and the control board with the sensor for detecting magnetic field lines. Another valve housing part, which is connected to the inner valve drive housing part at the end face, can accommodate at least the valve needle or part of the valve needle and the mechanism. The additional valve housing part can also be referred to as a valve needle seat.
[0016] The inner valve drive housing part can be made of a non-ferromagnetic metal, such as stainless steel, and sealed from the environment. The inner valve drive housing part can be designed as a dome or containment shell. The inner valve drive housing part can be a single piece or consist of two or more parts joined together. The outer valve drive housing part can be made of any material and serves to protect the control board, the magnetic field sensor, and the stator from contamination and damage. The magnetic field sensor can, in particular, be a Hall sensor.
[0017] The valve needle seat can accommodate the valve needle in such a way that it cannot rotate about a longitudinal axis in the valve needle seat, but can move linearly in an axial direction. In the axial direction, the valve needle seat can form a linear guide for the valve needle. The valve needle seat can further comprise a passage for a fluid, wherein the passage is completely closed in a first end position of the valve needle and completely open in a second end position of the valve needle. The valve needle can be continuously adjusted by the drive. Instead of continuously adjusting, the valve needle can be adjusted in very finely graduated, specific steps, for example, a gradation of 1000 or more steps. The material for the valve needle seat can be selected by a person skilled in the art depending on the fluid flowing through, e.g., its temperature, chemical composition, viscosity, etc.The valve needle seat is connected to the inner valve actuator housing part and is sealed from the environment in the connection.
[0018] The valve needle seat further comprises a through-opening for the fluid, which can be completely closed by the linear movement of the valve needle and opened continuously or gradually to a maximum.
[0019] A seal can also be arranged in the valve needle seat, which at least reduces leakage of the fluid flowing through the needle valve into the inner valve drive housing part.
[0020] The ferromagnetic metal body can, for example, be a cannula made of ferromagnetic stainless steel with a pressed-in steel plug. For easier identification and differentiation, the ferromagnetic metal body is also referred to below as a plunger. The cannula can engage with the hollow shaft and / or overlap the free end of the valve needle shaft. The plunger can be moved linearly together with the valve needle. The steel plug can have a minimum axial length that essentially corresponds to the maximum travel of the valve needle from the first end position (valve closed position) to the second end position (valve open position) plus the axial extension of the ring magnet. This means that the position of the valve needle can always be determined with a single measurement using a characteristic curve.If the plug has a deviating, shorter length, the measurement may result in a so-called bathtub curve, with two positions that cannot be clearly assigned. The minimum length of the plug can be, for example, 6 mm, 7 mm, 8 mm, or any other path length. In one embodiment, the path length can be >5.5 mm and <9 mm, preferably >6 mm and <8.5 mm. In one embodiment, the plunger can be a solid rod made of a ferromagnetic material.
[0021] In one embodiment, a cylindrical magnet can be arranged on the free end of the plunger, facing away from the valve needle. This cylindrical magnet is axially magnetized opposite to the ring magnet. The cylindrical magnet assists in short-circuiting the ring magnet by accelerating the magnetic flux through the upper end of the plunger.
[0022] When the plunger is positioned inside the ring magnet or enters the opening in the ring magnet, it essentially short-circuits the ring magnet. As a result, most of the field lines of the ring magnet's magnetic field no longer reach the sensor. Therefore, only a low flux density reaches the magnetic field sensor.
[0023] The valve needle shaft and the ferromagnetic metal body can have an identical diameter, for example, the diameter of the valve needle shaft in the area next to the external thread. If the inner diameter of the hollow shaft, the inner diameter of the opening in the ring magnet, and the inner diameter of the flux-conducting sleeve then essentially correspond to the specified diameter, the valve needle with the connected ferromagnetic metal body can be inserted into the hollow shaft from the side of the rotor facing away from the Hall sensor and screwed in. This enables simple production of the inner valve drive housing part or the containment shell, since it only needs to be open on one side.
[0024] The rotor can be rotatably mounted in at least one bearing, wherein the bearing can be arranged in the valve needle seat or the containment shell. The at least one bearing can be a rotary bearing for the rotor. Another rotary bearing can be formed in the containment shell above the end of the rotor facing the Hall sensor. In one embodiment, a plain bearing for the ferromagnetic metal body at the end of the valve needle shaft can be present in the containment shell below the Hall sensor. The plain bearing can form a receptacle for the ring magnet and / or the flux-conducting sleeve. The Hall sensor can in particular be a lateral Hall sensor or a linear Hall sensor, which offers the option of masking out or cutting off measured value ranges in order to "pick out" a profile range that is as linear as possible. The Hall sensor is arranged outside the inner valve drive housing part in an area above the hollow shaft.At least the hollow shaft, the rotor, and the valve needle share a common central longitudinal axis. The Hall sensor is arranged on the circuit board or on a side of the circuit board facing the containment shell such that this common central longitudinal axis intersects, does not intersect, or at least does not intersect centrally with the Hall sensor.
[0025] In one embodiment, a ferromagnetic half-shell with a central bore can be placed on the outer surface of the inner valve actuator housing to create a magnetic return path and thus better protect the sensor assembly against interference. Such a half-shell is complex to manufacture and incurs additional costs.
[0026] Finally, in a design with a multi-part containment shell, the upper end of the ferromagnetic metal part can be dimensioned differently and the structure above the rotor can be configured differently, since assembly through the hollow shaft is no longer necessary.
[0027] The needle valve enables highly accurate magnetic position determination of the valve needle, especially when there is a large distance between the ring magnet and the sensor. The magnetic field flux is conducted to the Hall sensor via a flux-conducting sleeve made of a ferromagnetic material. At the point of interest during the needle valve's closing process, a strong flux change is generated by short-circuiting the ring magnet. Sensor accuracy is increased with minimal material usage. This means that the solution offers a needle valve with low material costs (ring magnet, flux-conducting sleeve, steel cannula, steel plug, simplest Hall sensor), as well as weight and space savings, as the solution is space-neutral due to the simple integration of the ring magnet and flux-conducting sleeve into the upper plain bearing of the rotor.
[0028] In addition to the described needle valve, the subject matter of the invention can be advantageously used in all applications involving linear movements where the linearly moving parts are difficult to reach and / or encapsulated. Such applications include, for example, valves in drive motors, such as internal combustion engines, in the exhaust system, or in the brake booster. The invention enables the sensing of an end stop before it is actually reached, for example, in a steering system, a damper, or the brake booster. Furthermore, the invention can be used in all applications involving systems with expanding refrigerants (air conditioning systems), gas valves in turbines or boilers, and for detecting whether a locking bolt in a difficult-to-access installation location (e.g., rotor locking in offshore wind turbines) is truly open.
[0029] The following examples illustrate the needle valve design in more detail. The figures show:
[0030] Figure 1: a needle valve with Hall sensor in a vertical sectional view along the
[0031] axis of rotation of the rotor;
[0032] Figure 2: a detailed view of the upper part of the containment shell of the needle valve of Figure 1 in the valve-closed position;
[0033] Figure 3: a detailed view of the upper part of the containment shell of the needle valve of Figure 1 in an intermediate position;
[0034] Figure 4: an example of a flux density characteristic curve when moving the valve needle of the
[0035] Needle valve of Figure 1;
[0036] Figure 5: a detailed view of the upper part of a needle valve containment shell with an additional cylinder magnet on the steel plug;
[0037] Figure 6: an example of a flow density characteristic curve when moving the needle valve of the
[0038] Figure 5.
[0039] Figure 1 shows an embodiment of a needle valve 100. The needle valve 100 comprises a drive 50 or electromechanical drive with a rotor 52 and a stator 51. The stator 51 can, for example, have a core made of sheet iron and windings made of copper or copper wire. The rotor 52 can be a permanent magnet or be formed at least partially from permanent magnet material. The needle valve 100 further comprises a ring magnet 80. The rotor 52 can form a hollow shaft 53 or be rotationally connected to a hollow shaft 53. The rotor 52 radially surrounds the hollow shaft 53. A rotation axis or central longitudinal axis R of the rotor 52 is identical to a rotation axis or central longitudinal axis R' of the hollow shaft 53. The hollow shaft 53 is open at both axial ends. Inside the hollow shaft 53, between the two axial ends, an internal thread is formed in an axial section of the inner peripheral wall 53b.The internal thread 53a can, for example, be formed at an axial end of the hollow shaft 53.
[0040] The needle valve 100 further comprises a valve needle 10, which includes a valve needle shaft 12, a valve needle guide portion 13, and a valve needle tip 11. The valve needle shaft 12 has a free end 12b and an axially opposite end 12c that connects the valve needle shaft 12 to the valve needle guide portion 13. An external thread 12a is formed on the valve needle shaft 12 in a section between the free end 12b and the end 12c adjacent to the valve needle guide portion 13.
[0041] The valve needle guide section 13 is an engagement element 13a formed between the valve needle shaft 12 and the valve needle tip 11. The engagement element 13a interacts with a counter-engagement element 21 of the valve needle seat 20. If the valve needle guide section 13 or the engagement element 13a is in engagement with the counter-engagement element 21, the valve needle 10 is mounted in the valve needle seat 20 in a rotationally secure manner and can be moved in the axial direction X in a linear guide 21a.
[0042] A ferromagnetic metal body or plunger 70, for example a steel cannula 71 with a pressed-in steel plug 72, is connected to the free end 12b of the valve needle shaft 12. The steel plug 72 can have an axial length that essentially corresponds to a maximum travel path of the valve needle 10 from the valve closed position VZP to the valve open position VOP (Figure 2) plus the axial length of the ring magnet 80.
[0043] A bearing or plain bearing 54 is arranged above the rotor 52, which linearly guides the plunger 70 and / or rotatably supports the rotor 52 and / or axially supports the rotor 52 and the hollow shaft 53. The plain bearing 54 can be cast from plastic, for example. In the exemplary embodiment, the plain bearing 54 comprises a receptacle for the axially magnetized ring magnet 80 with a south pole S and a north pole N, wherein the ring magnet 80 is arranged in the plain bearing 54 close to the hollow shaft 53, and forms a receptacle for a flux guide sleeve 90, which extends from an axial end face of the ring magnet 80 to an axial end of the bearing 54 facing away from the rotor 52.
[0044] Below the rotor 52, another bearing or rolling bearing 55 is arranged, in the exemplary embodiment a pivot bearing for the rotor 52. The rolling bearing 55 can form the axial support for the rotor 52 and the hollow shaft 53 instead of the plain bearing 54.
[0045] The rotor 52, the plain bearing 54, the ring magnet 80, and the flux-conducting sleeve 90 are enclosed by a containment shell 56 or an inner valve drive housing part. The containment shell 56 is made of a non-ferromagnetic metal, such as stainless steel (e.g., X5CRNI18-10 V2A), and has a closed, bell-shaped dome that is open at the bottom. The containment shell 56 is connected to the valve needle seat 20 at its open end, with the connection area being sealed so that neither the interior of the containment shell 56 nor the interior of the valve needle seat 20 is connected to the environment.
[0046] The valve needle 10 can be inserted and screwed into the hollow shaft 53 with the valve needle shaft 12, whereby the external thread 12a of the valve needle shaft 12 is screwed into the internal thread 53a of the hollow shaft 53. The threaded connection of the hollow shaft 53 to the valve needle shaft 12 and the valve needle guide section 13 with the engagement element 13a and the counter-engagement element 21 together form a mechanism with which a rotary movement of the hollow shaft 53 is converted into an axial linear movement of the valve needle 10. The valve needle 10 has a central longitudinal axis R", which coincides with the rotational axis R' of the hollow shaft 53 and the rotational axis R of the rotor 52 when the valve needle shaft 12 is screwed into the hollow shaft 53.
[0047] The needle valve 100 further comprises a control board 30 which is connected to the stator 51 via a line L, so that a controller comprised by the control board 30 or connected to the control board 30 electrically controls the stator 51 so that it magnetically causes the rotor 52 to rotate at an adjustable rotational speed and adjustable rotational direction.
[0048] A magnetic field sensor 60 is connected to the control board 30 for detecting the local flux density emanating from the magnetic field of the ring magnet 80. The magnetic field sensor 60 can be a lateral Hall sensor or a linear Hall sensor. In the exemplary embodiment, the magnetic field sensor 60 is connected to a sensor holder 61 and arranged above the control board 30. The magnetic field sensor 60 rests above the hollow shaft 53 on the outside of the containment shell 56.
[0049] The stator 51, the control board 30, the magnetic field sensor 60, and the containment shell 56 are arranged in a drive housing 57. The drive housing 57 can be made of a suitable material, for example, plastic, and protects the aforementioned components from contamination and damage.
[0050] The valve needle seat 20 further includes a flow opening 40 for a fluid such as a coolant. The valve needle 10 or valve needle tip 11 can completely close the flow opening 40 in the valve-closed position (VZP) and open it fully in the valve-open position (VOP). A valve needle seal 14, which in the exemplary embodiment is arranged in the valve needle seat 20 below the mechanism, at least reduces fluid leakage through the valve needle seat 20 into the interior of the containment shell 56.
[0051] Figure 2 shows a detailed view of the upper section of the needle valve 100 of Figure 1.
[0052] The needle valve 100 is shown with the valve needle 10 in the valve-closed position VZP. The plain bearing 54 above the rotor 52 supports both the ring magnet 80 and the flux-conducting sleeve 90. The axial free end of the steel plug 72 lies at the level of or just below the axial end of the north pole N of the ring magnet 60, which in the exemplary embodiment faces the flux-conducting sleeve 90. The steel plug 72 is connected to the valve needle shaft 12 via a steel cannula 71 and can be moved linearly in the axial direction X together with the valve needle 10. The needle valve 100 can additionally comprise a half-shell (not shown) made of a ferromagnetic material, which bears tightly against a surface of the outer side of the containment shell 56 above the stator 51.The optional half-shell is drawn down to the stator lamination on the sides and has an opening at the top that is large enough to guide the magnetic flux through the magnetic field sensor 60 rather than bypassing it. The half-shell can, for example, have a similar wall thickness to the flux-conducting sleeve 90.
[0053] Because the steel plug 72 extends into the ring magnet 80, the axially poled ring magnet 80 is short-circuited within its interior, so that the magnetic field lines MFL are not conducted, or at least only partially, to the magnetic field sensor 60. The flux density drops as soon as the steel plug 72 enters the ring magnet. When the steel plug 72 reaches the upper edge of the ring magnet 80, the change in flux density is greatest. This maximum change in flux density can be directly attributed to the valve-closed position VZP.
[0054] Figure 3 shows essentially the same as Figure 2, except that the valve needle has been moved out of the valve-closed position VZP and is now located between the valve-closed position VZP and the valve-open position VOP.
[0055] The steel plug 72 still short-circuits the ring magnet 80, but together with the flux-conducting sleeve 90, it also forms an air gap area that increases the further the steel plug 72 moves into the flux-conducting sleeve 90. This short-circuits the magnetic field of the ring magnet 80 even more comprehensively, so that fewer magnetic field lines MFL are now conducted to the magnetic field sensor 60, which therefore measures a lower flux density. The lower flux density indicates that the valve needle 10 has left the valve-closed position VZP. The flux density changes most noticeably at the beginning of the opening movement and can be essentially constant once a certain degree of opening is reached.
[0056] Conversely, this means that when the valve closes, the flux density increases again and reaches a maximum when the steel plug 72 is fully extended from the flux guide sleeve. The unintentional complete extension of the steel plug 72 can be prevented by a mechanical end stop. This means that the flux density in the area of the valve-closed position (VZP) reaches a value that is below the maximum.
[0057] Figure 4 shows an exemplary characteristic curve KL1 for the linear movement of the valve needle 10 of a needle valve 100 with a magnetic flux density in the valve-closed position VZP of 23 mT and a magnetic flux density of 15 mT when the valve needle 10 has been moved by 1.2 mm from the valve-closed position VZP toward the valve-open position VOP. If the valve needle 10 is moved further toward the valve-open position VOP, the magnetic flux density essentially no longer changes.
[0058] Figure 5 shows a further embodiment in which the needle valve 100 includes a further magnet 85, which is also axially poled. The further magnet 85 is arranged at the free end of the steel plug 72, and the axial poles N, S of this further magnet 85 are aligned opposite to the poles N, S of the ring magnet 80. The further magnet 85 assists in short-circuiting the ring magnet 80. Furthermore, an additional high magnetic flux density is generated at the magnetic field sensor 60 when the valve needle is in the valve-open position VOP.
[0059] The characteristic curve KL2 for the needle valve 100 in Figure 5 is shown in Figure 6. Around the valve closed position VZP, the characteristic curve KL2 has an approximately linear function. At the valve open position VOP, the flux density drops sharply into the negative range. In the central section, the flux density hardly changes.
[0060] In Figure 5, the flux density in the valve-closed position VZP is over 30 mT, after a movement of the valve needle by 1.5 mm toward the valve-open position VOP it is approximately 18 mT, and remains essentially the same over a displacement length of the valve needle 10 of over 3 mm. If the valve needle is moved by 5 mm toward the valve-open position VOP, the flux density measured by the magnetic field sensor 60 is already only 16 mT and continues to decrease as the valve needle 10 moves further toward the valve-open position VOP. List of reference symbols 0 Needle valve
[0061] valve needle
[0062] Valve needle tip
[0063] Valve needle shaft a External thread b Free end c Connection end
[0064] Valve needle guide section a engagement element
[0065] seal
[0066] valve needle seat
[0067] Counter-engagement elements a linear guide
[0068] Control board
[0069] Flow opening
[0070] drive
[0071] stator
[0072] rotor
[0073] Hollow shaft a Internal thread b Inner peripheral wall
[0074] Bearings, plain bearings
[0075] Bearings, rolling bearings
[0076] containment shell
[0077] Drive housing
[0078] Magnetic field sensor
[0079] Sensor holder
[0080] Diving anchor
[0081] Cannula
[0082] Steel plug, plug 80 ring magnet
[0083] 85 Magnet
[0084] 90 flux guide sleeve
[0085] KL1 characteristic curve
[0086] KL2 characteristic curve
[0087] L Line
[0088] MFL magnetic field line
[0089] N North Pole
[0090] R central longitudinal axis
[0091] R' central longitudinal axis
[0092] R" central longitudinal axis
[0093] S South Pole
[0094] VOP Valve open position
[0095] VZP valve closed position
[0096] X axial direction
[0097] Y radial direction
Claims
Patent claims 1. Needle valve (100) with magnetic position determination of the valve needle (10), with a. a valve needle seat (20), b. a containment shell (56), c. a control board (30), d. an electric drive (50) with a stator (51) and a rotor (52), wherein the rotor (52) is arranged in the containment shell (56), e. a hollow shaft (53) with an internal thread (53a), which is formed by the rotor (52) or is connected to the rotor (52) in a rotationally fixed manner, f. at least one bearing (54, 55) for the rotor (52), g. a valve needle (10) with a valve needle tip (11) and a valve needle shaft (12) with an external thread (12a), h. a magnetic field sensor (60) which is arranged outside the containment shell (56) in an axial direction (X) above the hollow shaft (53), and i.wherein the external thread (12a) of the valve needle shaft (12) meshes with the internal thread (53a) of the hollow shaft (53) and a mechanism converts the rotational movement of the hollow shaft (53) into a linear movement of the valve needle (10) in the axial direction (X), j. at least the rotor (52), the hollow shaft (53) and the valve needle (10) are arranged axially symmetrically with a common central longitudinal axis (R, R', R"), characterized in that k. the needle valve (100) further comprises a ring magnet (80) which is arranged above the rotor (52) in an extension of the hollow shaft (53), and l. a ferromagnetic metal body (70) which is connected to a free end (12b) of the valve stem (12).
2. Needle valve (100) according to claim 1, wherein the needle valve (100) further comprises a Flux guide sleeve (90) which is arranged in the axial direction (X) above the ring magnet (80).
3. Needle valve (100) according to one of the preceding claims, wherein at least the rotor (52), the hollow shaft (53), the ferromagnetic metal body (70) and the ring magnet (80) are arranged in the containment shell (56).
4. Needle valve (100) according to one of the preceding claims, wherein the stator (51) is arranged outside the containment shell (56), radially surrounds the containment shell (56) and the stator (51) drives the rotor (52) without contact.
5. Needle valve (100) according to one of the preceding claims, wherein the magnetic field sensor (60) is arranged eccentrically or coaxially with the common central longitudinal axis (R, R', R").
6. Needle valve (100) according to one of the preceding claims, wherein the ring magnet (80) has an axial magnetization, with a south pole (S) and a north pole (N), and wherein the ferromagnetic metal body (70) moves into the ring magnet (80) during a linear movement of the valve needle (10) and short-circuits the inner region of the ring magnet (80).
7. Needle valve (100) according to one of the preceding claims, wherein the ferromagnetic metal body (70) comprises a cannula (71) made of ferromagnetic material and a highly permeable flux guide piece (72), 8. Needle valve (100) according to claim 7, wherein a minimum axial length of the highly permeable flux guide piece (72) corresponds to the maximum travel distance of the valve needle (10) from a valve-closed position (VZP) in which the needle valve (100) is completely closed, to a valve-open position (VOP) in which the needle valve (100) is maximally open, and the axial extent of the ring magnet (80).
9. Needle valve (100) according to one of the preceding claims, wherein the needle valve (100) further comprises a further axially magnetized magnet (85) having a magnetization opposite to the magnetization of the ring magnet (80) is aligned, wherein the further magnet (85) is arranged at a free axial end of the ferromagnetic metal body (70).
10. Needle valve (100) according to one of the preceding claims, wherein the needle valve (100) is a coolant valve.