Valve device

Abstract

The invention relates to a valve device comprising - a valve having a movable piston (21) for closing and opening the valve, - a magnet (22) or a magnetizable element and - a sensor unit (6) having a magnetic-field sensor (64) for determining the position of the piston (21). The magnet (22) or the magnetizable element and the sensor unit (6) are movable relative to one another by the movement of the piston (22). The magnetic-field sensor (64) is designed to measure an at least two-dimensional vector of a magnetic flux density. An analysis unit determines a change in the angle of the at least two-dimensional vector. The valve device and a corresponding method allow for the precise determination of the position of the piston even in a confined space.

Description

[0001] TITLE

[0002] VALVE DEVICE

[0003] TECHNICAL FIELD

[0004] The present invention relates to a valve device, in particular a valve device in a high-pressure environment, for example, for hydrogen applications. It particularly relates to a valve device for hydrogen filling stations. It is also suitable for use in blow molding devices, for example, in an extrusion blow molding or stretch blow molding machine for producing hollow plastic bodies using compressed air. The invention also relates to a method for determining the position of a piston in this valve device.

[0005] STATE OF THE ART

[0006] Valve devices are used in a variety of applications. Electromagnetically and / or pneumatically operated valves open and close according to a control system.

[0007] In many applications, there is a need to detect whether the valve is open or closed. This is the case, for example, with valves in high-pressure environments, especially in hydrogen applications such as hydrogen refueling stations.

[0008] It is known in the art to use magnetic field sensors, in particular Hall sensors, to monitor a valve.

[0009] DE 37 30 940 A1 discloses a pilot-operated directional control valve with a movable piston whose position is measured by a Hall sensor. A permanent magnet is located centrally in the piston. The Hall sensor is fixed in an intermediate plate between a pilot control and a valve housing.

[0010] DE 44 17464 A1 shows a valve with a coil member actuated by a pilot part and a Hall sensor which detects the movement tendency of the coil member in order to determine whether the coil member is not stuck.

[0011] CN 103148222 A describes a hydraulic control valve with an electromagnetic pilot valve and a Hall sensor.

[0012] The magnetic field sensors determine the respective field strength and can thus detect whether the valve is closed or open. The magnetic field sensor must be positioned relatively close to the movable magnetic field transmission means, i.e., the permanent magnets, to ensure reliable measurement. However, such a close location is often difficult due to space constraints. Furthermore, interfering elements, such as metal components or magnetic coils, influence the measurement. Furthermore, in some applications, it is advantageous to be able to detect intermediate valve positions. This is the case, for example, for troubleshooting in manufacturing processes or for safety reasons.

[0013] PRESENTATION OF THE INVENTION

[0014] It is therefore an object of the invention to provide an improved valve device with position determination of the piston.

[0015] This object is achieved by a valve device having the features of claim 1 or 16 and by a method having the features of claim 15.

[0016] In some embodiments, the valve device according to the invention comprises a valve having a movable piston for closing and opening the valve. The valve device comprises a magnet or a magnetizable element and a sensor unit having a magnetic field sensor for determining a position of the piston. The magnet or the magnetizable element and the sensor unit are movable relative to one another by the movement of the piston. The magnetic field sensor is designed to detect an at least two-dimensional vector of a magnetic flux density. An evaluation unit is provided that determines an angular change of the at least two-dimensional vector.

[0017] In a method for determining the position of a piston in a valve device, the magnetic field sensor detects an at least two-dimensional vector of a magnetic flux density. According to the invention, the angular change of the at least two-dimensional vector is determined by means of the evaluation unit. The angular change occurs when the magnet or the magnetizable element moves relative to the sensor unit upon movement of the piston.

[0018] In contrast to known position sensors, the field strength is not determined, but the magnetic field is evaluated in at least two directions. This means that the measurement is no longer dependent on the temperature dependence of the magnet's field strength. Preferably, the field is measured two-dimensionally or three-dimensionally and a spatial vector is calculated. A transformation from a Cartesian coordinate system to a spherical coordinate system preferably takes place. Preferably, a coordinate system with a zero point in the magnetic field sensor is related to a coordinate system with a zero point in the magnet or in the magnetizable element. Preferably, it is aligned accordingly for this purpose without the zero points of the two coordinate systems coinciding. Preferably, the coordinate system with a zero point in the magnetic field sensor is rotated so that a main axis of the coordinate system is parallel to a direction of movement of the valve piston.

[0019] Thanks to the inventive solution, the magnetic field sensor no longer necessarily needs to be positioned perpendicular to the longitudinal axis of the piston or parallel to it. It can also be aligned at an angle to the piston. This increases the possibilities for installing the sensor unit in the valve device. This is particularly advantageous in confined spaces. A specific design of the sensor unit according to the invention can be used in differently designed valve devices thanks to its flexibility in terms of installation. This minimizes manufacturing costs, since the same type of sensor unit can be used multiple times.

[0020] If the valve device has two or more valves, the flexibility of the sensor unit arrangement also allows two or more sensor units to be arranged within the valve device. This allows more than one valve of a valve device, in particular a valve block, to be monitored with a dedicated sensor unit.

[0021] If the magnetic field sensor is located in the stationary part of the valve device, it can be positioned close to the movable piston. This increases measurement accuracy.

[0022] A more precise measurement of the position is possible. Interference can be eliminated more easily. Furthermore, intermediate positions of the piston can also be determined, so that not only the open and closed positions are detected. However, depending on the embodiment, the specified position is not necessarily an exact position; rather, in at least some embodiments, the closed and open states are indicated within a range. If an optical display is present, for example, a red light can indicate a fully to almost fully open state of the valve, a green light indicates a fully or almost fully closed state of the valve, and a blue light indicates the intermediate position of the piston. Other embodiments feature other colors and / or finer gradations.

[0023] Preferably, all coordinates of the Cartesian coordinate system are used for the conversion to the spherical coordinate system. If the sensor unit is mounted in the valve block in an unaligned position, preferably only the axial angle and the magnitude of the vector, i.e., its length, are taken into account. If the sensor unit is mounted in the valve block in an aligned position, preferably also the radial angle is taken into account.

[0024] In preferred embodiments, however, the three-dimensional vector is both determined and evaluated. This increases measurement accuracy and allows for a free choice of the angle at which the magnetic field sensor is positioned relative to the piston or the measured magnetic field. In preferred embodiments, the magnetic field sensor is therefore designed to detect a three-dimensional vector of a magnetic flux density.

[0025] Any magnetic field sensor designed to detect the spatial vectors of the magnetic field lines can be used. The magnetic field sensor is preferably at least a 2D Hall sensor, and even more preferably at least a 3D Hall sensor. In preferred embodiments, the magnet is a permanent magnet. The permanent magnet is preferably made of a hard magnetic material. In other embodiments, the magnet is an electromagnet.

[0026] The magnetizable element is preferably made of a soft magnetic material and more preferably of a magnetically conductive material with low remanence and even more preferably of a magnetically conductive material with very low remanence.

[0027] Preferably, the magnet or magnetizable element is arranged in the piston, and the sensor unit is fixed in position. This facilitates the assembly of the sensor unit and enables a cable connection from the sensor unit to a control device. Furthermore, the piston can be manufactured cost-effectively.

[0028] If the magnetizable element is arranged in the piston, an associated magnet, in particular a permanent magnet or an electromagnet, is preferably arranged in a stationary manner, preferably adjacent to the sensor unit.

[0029] The magnet or magnetizable element defines a three-dimensional Cartesian coordinate system with three axes. The zero point is preferably located at the center of the magnet when the valve is closed. The sensor unit also defines a three-dimensional Cartesian coordinate system with three axes. The zero point is preferably located at the center of the sensor element.

[0030] The magnetic field sensor can be positioned anywhere in the magnet's coordinate system. However, taking the available space into account, it is preferably positioned so that it can optimally detect angular changes in the two-dimensional or three-dimensional magnetic flux density vector caused by the movement of the piston.

[0031] Depending on the design of the valve unit and the available space, the magnetic field sensor can also be positioned at an angle, i.e., obliquely, to the three axes of the Cartesian coordinate system, or to at least one of them. This means that the sensor elements can be positioned obliquely to the axes.

[0032] The magnet or magnetizable element is preferably disc-shaped, annular, cylindrical, prismatic, or rod-shaped. If the valve piston is rotatable, the magnet or magnetizable element is preferably rotationally symmetrical.

[0033] Preferably, the magnet or magnetizable element is arranged centrally to a longitudinal center axis of the piston. This facilitates the calculation of the piston's position, as its longitudinal center axis coincides with an axis of the Cartesian coordinate system. This is particularly advantageous for a rotatable piston.

[0034] Preferably, in the method according to the invention, the detected magnetic field vector is converted from the Cartesian coordinate system of the sensor unit into a spherical coordinate system.

[0035] Preferably, not only the magnetic field sensor, but the entire sensor unit is arranged obliquely, i.e., at an angle other than 0° and preferably not 90°, to a longitudinal center axis of the piston. This facilitates the placement of the sensor unit in the valve device close to the piston, particularly in confined spaces. This facilitates compact designs. In particular, in so-called manifolds of hydrogen filling stations, in which a plurality of valve devices are combined in a matrix-like manner to form a single unit, it is possible to equip each valve device with at least one sensor unit.

[0036] Some valve devices have solenoid valves with a conductor coil that generates a magnetic field. This solenoid valve can be the one whose piston is to be monitored by the sensor unit. However, it can also be a second valve arranged adjacent to the monitored valve, for example, within the same valve block. For example, it can be a pilot valve of a pilot-operated pneumatic valve. The magnetic field generated by the conductor coil influences the magnetic field measurement. Such solenoid valves are subject to wear and tear and must therefore be replaced regularly. To ensure consistent measurement when a solenoid valve is replaced, it is advantageous if the conductor coil is arranged in the valve device with a predefined current flow direction. This ensures that the interference field generated by the conductor coils is always directed in the same direction within the valve device.This ensures that the polarity of the interference field is always consistent with respect to the piston and the magnetic field sensor. If the magnet is located in the piston, it is regularly replaced along with the piston during maintenance. Therefore, the magnetic pole in each piston is preferably always aligned in the same way. The interference field can be accounted for or compensated for by the evaluation unit in the same way.

[0037] The influence of the magnetic field of the conductor coil can be reduced if the housing of the solenoid valve is made of metal. This is particularly the case when the solenoid valve is not the monitored valve. Alternatively, or in addition, the influence of the interference field can be reduced if a deflection element made of a magnetically conductive material is arranged between the conductor coil and the magnetic field sensor. This is particularly advantageous when the solenoid valve is not the monitored valve. The deflection element is preferably made of a magnetically conductive material, i.e. a magnetizable material, for example steel. It deflects the magnetic field lines of the interference field in a suitable manner. The deflection element is, for example, an annular plate or a sleeve, which is preferably arranged around the armature of the solenoid valve or forms part of the armature, preferably the part facing away from the conductor coil.The sleeve is preferably part of the anchor's guide tube.

[0038] The use of a deflection element is claimed here as an independent invention. This magnetic field deflection element can also be used in other sensor units for valve devices, without the sensor unit determining the angle changes or being arranged at an angle.

[0039] Magnetic field sensors are temperature-dependent. Furthermore, magnetic field sensors and other components of the sensor unit, such as the evaluation unit, can typically only be used down to temperatures of approximately -40°C. However, valve units for hydrogen applications are sometimes exposed to temperatures as low as -50°C or lower. Therefore, the sensor unit preferably has a heater for heating the magnetic field sensor and / or the evaluation unit. A heating resistor is preferably used. Depending on the embodiment, the heater primarily heats the magnetic field sensor with or without the evaluation unit and / or other components of the sensor unit. In some preferred embodiments, the evaluation unit is a component of the sensor unit, in particular part of a microprocessor of the control unit. In other embodiments, it is part of a separate controller.

[0040] Preferably, the magnetic field sensor is tempered to a predetermined temperature or within a predetermined temperature range, i.e., maintained at this temperature. This increases measurement accuracy. For this purpose, the sensor unit preferably has a temperature sensor.

[0041] If the sensor unit includes additional components, such as the evaluation unit, it is advantageous for safety reasons if all components are arranged in a housing with a potted cavity. For example, explosion protection must be ensured for many applications. The potting compound is preferably epoxy, polyurethane, or silicone. While such potting compounds protect the components, they also act as thermal insulators. The housing, at least the tip, i.e., the free end area, is preferably made of plastic. This allows for the formation of a thin end area while simultaneously meeting the requirements for sufficient explosion protection. The housing is preferably constructed in one piece.

[0042] In order to enable optimal temperature control of the magnetic field sensor with minimized heating power even with encapsulated sensor units, the components are preferably arranged as follows: The magnetic field sensor is arranged on a first side of a circuit board and the heater is arranged on a side of the circuit board opposite the first side. The circuit board has through-openings that extend in the area of ​​the heater from the second side to the first side of the circuit board. The through-openings are also called vias. A heat conductor is arranged in the through-openings. For this purpose, the inner wall of the vias is preferably coated over their entire length with a layer of copper or another material with good heat conduction. This directs the heat from the heater to the side of the magnetic field sensor. The electrical conductors arranged on this side conduct the heat to the magnetic field sensor.The heater is preferably arranged adjacent to, but at a distance from, the magnetic field sensor. A thermal pad, i.e. a heat-conducting mat, is preferably arranged between the heater and the circuit board in order to conduct the heat generated by the heater into the vias. The heating power required to control the temperature of the components, in particular of the magnetic field sensor, can be minimized by applying some or all of these measures. Copper tracks of the circuit board preferably also serve as heat conduction, in particular on the side of the heater. Arranging the heater on the side of the circuit board opposite the magnetic field sensor enables a space-saving arrangement. In some embodiments, however, the heater is arranged on the same side as the magnetic field sensor. A temperature-dependent heating resistor is preferably used as the heater, the heat output of which decreases as the temperature increases.Preferably, its resistance increases exponentially above a certain temperature. This prevents overheating and increases explosion protection. A PTC resistor is preferably used.

[0043] The arrangement of the heater on the side of the circuit board opposite the magnetic field sensor and the heat transfer via the vias are hereby claimed as an independent invention. This arrangement can also be used in other sensor units for valve devices without the sensor unit determining the angular changes or being arranged at an angle. In a preferred variant, the through-openings are provided with a thermally conductive material; preferably, the inside is coated accordingly or the through-openings are completely filled with a thermally conductive material. Alternatively or additionally, a thermally conductive pad is preferably arranged between the heater and the circuit board. Alternatively or additionally, a thermally conductive pad is present between the magnetic field sensor and the circuit board. The components are preferably located in a cast-in housing of the sensor unit.

[0044] The circuit board is preferably multilayered. It is preferably an FR-4 circuit board, meaning it is made of a flame-resistant and flame-retardant material.

[0045] The sensor unit is preferably rod-shaped. It preferably has a housing, which has an elongated shape and terminates in a free end region. The magnetic field sensor is preferably arranged in the free end region. The housing preferably contains all components of the sensor unit. The evaluation unit is preferably also a component of the sensor unit and is therefore preferably also arranged in the housing.

[0046] The arrangement of the magnetic field sensor in the free end area, particularly in a tapered end area, of the housing has the advantage that it can be positioned as close as possible to the piston or its magnet in the valve device. This optimizes the measurement. The housing preferably has means for fixing the sensor unit in a recess of the valve device, particularly the valve block.

[0047] Preferably, a cable is provided for connecting to an external control unit. The cable is preferably encapsulated in the housing and additionally secured with a cable gland. This increases explosion protection.

[0048] In some embodiments, the sensor unit according to the invention forms a stand-alone unit that can be arranged in the valve device, in particular in a valve block. It can preferably be inserted into and removed from a valve block mounted in a system. This facilitates maintenance of the valve device or the system. The sensor unit has the magnetic field sensor for determining the position of the piston. The magnetic field sensor is designed to detect an at least two-dimensional vector of a magnetic flux density. The sensor unit designed as a stand-alone unit preferably also has the evaluation unit, which determines an angular change of the at least two-dimensional vector.

[0049] The sensor unit is preferably connected to a control unit of the valve device or a system in which the valve device is used. The sensor unit preferably transmits the status information about the piston to this control unit. Thus, the information about the piston's current state is available digitally.

[0050] Alternatively or additionally, the sensor unit preferably has a visual display which indicates whether the sensor unit is operational. Alternatively or additionally, it can indicate the position of the piston. The visual display is, for example, a light, in particular from one or more LEDs which are arranged in a housing of the sensor unit. In particular, they are arranged on the circuit board. Preferably, there is at least one opening, i.e. a window, in the housing for the visual position display. The visual display is preferably visible to a user even if the valve device is installed together with the sensor unit in a system. Alternatively, the housing or a cable gland can be designed to be at least partially transparent in order to ensure a visual display. The light preferably exits to the rear. The transparent design has the advantage that the visual display is clearly visible.Furthermore, no seals and / or additional components are required for the light exit. This also minimizes costs. In some embodiments, the valve device according to the invention comprises a valve having a movable piston for closing and opening the valve. The valve device comprises a magnet or a magnetizable element and a sensor unit having a magnetic field sensor for determining a position of the piston. The magnet or the magnetizable element and the sensor unit are movable relative to one another by the movement of the piston. The magnetic field sensor, preferably the entire sensor unit, is arranged obliquely to a longitudinal center axis of the piston and / or the magnet. Depending on the embodiment of this valve unit, the measurement is carried out as stated above by determining the angular change or by means of another measuring method, in particular by determining the field strength.This valve device can be combined with the features of the dependent claims and the above features, even without determining the angle change. This is particularly true when using compensation for the temperature dependence of the field strength measurement or when the magnet temperature is kept constant.

[0051] Further embodiments are specified in the dependent claims.

[0052] BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Preferred embodiments of the invention are described below with reference to the drawings, which are for illustrative purposes only and are not to be construed as limiting. In the drawings:

[0054] Figure 1 is a perspective view of a valve device according to the invention in a first embodiment;

[0055] Figure 2 shows a longitudinal section through a valve device according to the invention in a second embodiment;

[0056] Figure 3 shows a longitudinal section through a valve device according to the invention in a third embodiment;

[0057] Figure 4 is a perspective view of the sensor unit according to the invention shown in Figure 1; Figure 5 is a longitudinal section through the sensor unit shown in Figure 4;

[0058] Figure 6 shows a partial section through the sensor unit according to Figure 4 in an enlarged

[0059] Depiction;

[0060] Figure 7 is a perspective view of part of the sensor unit according to Figure 4,

[0061] Figure 8 is a schematic representation of a valve device according to the invention in a fourth embodiment showing a Cartesian magnetic coordinate system related to the piston in a first view;

[0062] Figure 9 is a schematic representation of the valve device according to Figure 8 in a second view;

[0063] Figure 10 shows the sensor unit according to Figure 6 with the Cartesian sensor coordinate system and spherical coordinate system of the sensor unit drawn in;

[0064] Figure 11 shows a longitudinal section through a valve device according to the invention in a fifth embodiment;

[0065] Figure 12 shows a longitudinal section through a valve device according to the invention in a sixth embodiment;

[0066] Figure 13a shows a part of the valve device according to Figure 12 in a first end position of the piston of a valve with representation of magnetic field lines;

[0067] Figure 13b shows the representation according to Figure 13a as a black and white line drawing;

[0068] Figure 14a shows the part of the valve device according to Figure 12 in a second end position of the piston;

[0069] Figure 14b shows the representation according to Figure 14a as a black and white line drawing;

[0070] Figure 15 is a schematic representation of a part of the valve device according to Figure 12 with coordinate systems and simplified magnetic field lines; Figure 16 is a schematic representation of a part of the valve device according to Figure

[0071] 12 with coordinate systems and simplified magnetic field lines and

[0072] Figure 17 is a flow chart explaining the evaluation of the measurement data of the sensor unit in a variant of the method.

[0073] Identical or similar parts and components are provided with the same reference symbols.

[0074] DESCRIPTION OF PREFERRED EMBODIMENTS

[0075] The valves illustrated in the figures serve to illustrate the invention. Other types of piston valves can also be used. The features illustrated in the individual figures are also present in the embodiments according to the other figures or can at least be integrated into these embodiments. The description below for each figure also applies accordingly to the valves in the other figures. In the following description of a figure, references are therefore occasionally made to another figure in order to explain a feature that is not or not sufficiently recognizable in this way in the currently described figure.

[0076] Figure 1 shows a first embodiment of a valve device according to the invention. It has a valve block 1 with a main valve 2 (not visible in this figure) with a movable piston 21 and with a housing of a solenoid valve 3, also called a pilot valve. The main valve 2 and the piston 21 can be seen, for example, in Figure 2. A sensor unit 6 is arranged in a receiving opening of the valve block 1, with the sensor unit 6 partially protruding from the receiving opening, here a bore. The sensor unit 6 is arranged at an angle to a direction of movement of the piston 21, i.e. it is arranged obliquely to a longitudinal axis of the piston 21.

[0077] In Figures 8 and 9, the longitudinal axis of the piston is designated Li and the longitudinal axis of the sensor unit is designated L2. The piston 21, or a magnet 22 arranged on or in the piston 21, defines a Cartesian magnetic coordinate system Xi, Y1, Z1. The Yi axis of the magnetic coordinate system preferably runs parallel to the longitudinal axis of the piston and thus to its direction of movement. The zero point of the magnetic coordinate system is preferably located in the magnet 22. If, instead of the magnet 22, a magnetizable element is arranged on or in the piston, the zero point is preferably located in this element. A corresponding magnetic spherical coordinate system is not shown. However, one can be easily created by a person skilled in the art.

[0078] The sensor unit 6 is thus arranged at an angle to the piston 21. "Oblique" means that the sensor axis L2 runs at an angle other than 0° to at least two, preferably each of the three, axes of the Cartesian coordinate system of the piston 21 or the magnet 22.

[0079] Figure 2 shows a second embodiment of a valve device according to the invention, wherein the sensor unit 6 and the valve unit are the same as in Figure 1. The valve unit itself is known. Its functionality essentially corresponds to the valve shown in Figure 6 of WO 2022 / 109041 A1.

[0080] The main valve 2 has a stationary valve body 20 and a movable piston 21. A magnet 22 is arranged in the piston 21. It is preferably arranged in the free end of the piston 21, i.e., facing away from the valve body 20. The magnet 22 is preferably annular, disc-shaped, or rod-shaped.

[0081] The solenoid valve 3 has an electrical connection and a magnetic part with a magnetic coil housing 30 and a magnetic coil 32. A guide tube 33 and an armature 34 are arranged in the magnetic part. The magnetic coil 32, the guide tube 33, and the armature 34 can be seen in Figure 8. The guide tube 33 is usually made of a non-magnetic material. Depending on the design, it is made of one, two, or three parts. In a multi-part design, one part of the guide tube can be magnetizable and another part non-magnetizable. The orientation of the magnetic field generated by the magnetic coil 32 can be seen in Figure 8 by the indication of the north pole N and the south pole S. This orientation is preferably known. However, it can also have a different polarity.

[0082] An inlet channel 10 leads through the valve block 1 from the outside into a valve chamber 12 of the valve block 1. An outlet channel 11 leads from the valve chamber 12, also through the valve block 1, to the outside. In this example, the inlet channel 10 and the outlet channel 11 run parallel and offset from one another. Other alignments are possible. An inlet line 4 is arranged in the inlet channel 10. An outlet line 5 is arranged in the outlet channel 11. The piston 21 closes the valve chamber 12 from the inlet channel 10.

[0083] The sensor unit 6 is again arranged at an angle in the valve block 1. It can be tilted relative to two of the three coordinate axes of the magnet or relative to all three coordinate axes. In Figure 1, it is tilted relative to all three coordinate axes. In Figure 2, the sensor unit 6 extends parallel to the third coordinate axis, which runs in the plane of the drawing.

[0084] The receiving opening for the sensor unit 6 is located between the inlet opening 10 and the solenoid valve 3.

[0085] The sensor unit 6 is rod-shaped. It has a housing 60 with an external thread 601. It is screwed into the receiving opening of the valve block 1. The use of a thread is only one of several ways in which the sensor unit 6 can be fixed in the valve block. Alternatives include, for example, a bayonet lock or a snap, spring, or clamp connection without rotation of the sensor unit. In some embodiments, the rotational position is indeterminate in the assembled state. In other embodiments, directional installation is possible, so that the sensor unit is arranged in a defined rotational position in the valve block 1. This can be achieved, for example, by means of a groove in the sensor unit and a corresponding pin in the valve block.

[0086] In a further variant, in addition to the external thread 601, there is a snap ring with a sleeve with an external thread that surrounds the housing. The snap ring can be positioned and secured in various longitudinal positions on the external thread 601 of the housing 60. The external thread 601 is shorter than in the embodiment shown in the figures. The connection to the valve block 1 is made via the external thread of the sleeve of the snap ring. This prevents the sensor unit 6 from rotating when it is fastened in the valve block. In addition, the sensor unit 6 can be screwed into the valve block 1 to different depths. A sensor cable 62 is firmly connected to the housing 60, preferably by means of a cable gland 61. The sensor cable 62 is preferably also encapsulated in the housing 60, for example with epoxy.

[0087] The opposite free end region 600 of the sensor unit 6 is preferably tapered. A magnetic field sensor 64 is arranged at its tip or near the tip. The free end region 600 and thus the magnetic field sensor 64 are arranged in optimal proximity to the magnets 22 of the movable piston 21. This allows the position of the piston 21 to be detected by the magnetic field sensor 64.

[0088] Figure 3 shows a variant of the valve device according to Figure 2. It differs in that the receiving opening for the sensor unit 6 is located between the outlet opening 11 and a receiving opening of the valve body 20.

[0089] Figures 4 to 7 show the sensor unit 6. It is rod-shaped and has a housing 60 with a tapered free end region 600. The sensor cable 62 is inserted into the housing 60 and is firmly connected to the housing 60 by means of the cable gland 61. The cable ends 620 are soldered to a circuit board 63.

[0090] The circuit board 63 is completely surrounded by the housing 60. The housing 60 is preferably at least partially encapsulated, preferably with epoxy.

[0091] In the free end region 600, the circuit board 63 is preferably tapered. The magnetic field sensor 64 is arranged at its front end. It is preferably a 2D Hall sensor and more preferably a 3D Hall sensor. Alternatively, it is another sensor that can detect the field vectors of the magnetic field of the magnet 22 in two- or three-dimensional space.

[0092] Preferably, a microcontroller 67 is arranged on the circuit board 63. It has an evaluation unit for evaluating the signals from the magnetic field sensor 64. The microcontroller 67 is preferably arranged in the wider area of ​​the circuit board 63.

[0093] Furthermore, at least one light-emitting diode (LED) 68 is present on the circuit board 63. It is positioned adjacent to at least one window 602. The window 602 is preferably tightly sealed, for example, potted. Alternatively, the cable gland 61 is transparent.

[0094] Furthermore, a heater 65 is provided, which is preferably arranged in the free end region 600 adjacent to the magnetic field sensor 64 on the circuit board 63. The heater 65 is preferably offset in the longitudinal direction of the sensor unit 6 and at a distance from the magnetic field sensor 64 on the opposite side of the circuit board 63. If sufficient space is available, the heater 65 can also be arranged on the same side of the circuit board 63 as the magnetic field sensor 64.

[0095] Figure 7 shows only a portion of the printed circuit board 63 in this area. The top and bottom sides of the printed circuit board 63 are visible and marked with the reference symbol 63. The outlines of the printed circuit board 63 are not shown. The material of the printed circuit board 63 between this top and bottom sides is also not visible.

[0096] In Figure 7, the conductor tracks 632 of the circuit board 63 can be seen, some of which lead from the microcontroller 67 to the heater 65 and the magnetic field sensor 64. In order to guide the heat from the heater 65 to the magnetic field sensor 64,

[0097] 63 through-holes 630, also called vias, are present. They are cylindrical, with their inner walls coated with copper. The copper walls 631 are visible in Figure 7. To optimally conduct heat, a thermal pad is preferably arranged between the underside of the circuit board 63 and the heater 65. This is not visible in the figures.

[0098] If the valve device has a solenoid valve, the magnetic field of the solenoid valve's conductor coil can influence the measurement of the magnetic field sensor 64. If the solenoid valve is arranged in a housing made of magnetically conductive material, the interference field is already reduced because the magnetic field lines of the magnetic field generated in the conductor coil are redirected toward the housing.

[0099] An alternative or additional reduction of the interference field is the installation of a deflection element, which separates the magnetic field of the solenoid valve from the magnetic field sensor

[0100] 64 away. The deflection element consists of a material with good magnetic conductivity. Two examples are shown in Figures 11 and 12. In Figure 11, an annular plate 7 made of a material with good magnetic conductivity surrounds the guide tube 33 of the armature 34 of the solenoid valve 3. In Figure 12, in addition to the annular plate 7, a sleeve 8 made of a material with good magnetic conductivity is present. The sleeve 8 is preferably a magnetizable part of the otherwise non-magnetizable guide tube 33. The sleeve

[0101] 8 can also be used without ring plate 7.

[0102] Figure 10 shows a Cartesian sensor coordinate system x, y, z and a corresponding spherical coordinate system M, a, ß, whose zero points are identical and which run through the magnetic field sensor 64. The y-axis runs in the longitudinal direction of the sensor unit 6. The radial angle α is defined in the xz-plane and is determined by the projection of the 3D field vector of the magnetic field sensor 64. It has a value range of 0 to 360°. The axial angle ß has a value range of 0 to 180°. It lies in the plane spanned between the 3D vector of the field strength and the y-axis. This plane rotates around the y-axis when the 3D vector rotates around the y-axis. A rotation of the sensor unit 6 about the y-axis, ie about the rotation axis when screwing the sensor unit 6 into the valve block 1, thus influences only the radial angle α, but not the axial angle β. Therefore, the axial angle β is preferably evaluated, but not the radial angle α.However, if the sensor unit 6 is mounted in the valve block 1 in an aligned manner, the radial angle a can also be evaluated. The illustrated arrangement of the sensor coordinate system corresponds to an ideal arrangement in which the sensor element of the magnetic field sensor is positioned at the zero point. In practice, a zero point correction is usually necessary for the field vector measured by the magnetic field sensor, as described further below in Figures 14a and 14b.

[0103] Figures 13a, 13b and 14a, 14b show the magnetic field lines of the solenoid valve 3 and the magnet 22 of the monitored piston 21. The armature 34 is shown schematically. The sleeve 8 is provided with the annular plate 7.

[0104] The magnet 22 is arranged in the piston 21. The poles of the magnet 22 are, as can be seen from the magnetic field lines 9 shown, at the top and bottom in the direction of movement of the piston 21.

[0105] The piston 21 is not shown in the figures. However, the magnet 22, which is fixedly connected to the piston 21, indicates its position in Figures 13a, 13b and 14a, 14b. The position of the armature 34 of the solenoid valve 3, i.e., the magnetic part, can be seen from the illustrated retaining ring 34 of the magnetic part. The retaining ring 34 is also called a Seeger ring. In Figures 13a, 13b, the piston 21 is in a first end position of the piston 21 and thus in the open state of the main valve, and in Figures 14a, 14b, the piston 21 is in a second end position of the piston 21 and thus in the closed state of the main valve.

[0106] The free end region 600 of the sensor unit and the magnetic field sensor 64 are schematically illustrated in both Figures 13a, 13b, 14a, and 14b. They are arranged in a fixed position in the valve device.

[0107] As can be seen, the magnetic field lines of the interference field 90 of the conductor coil 32 are deflected into the sleeve 8 and the ring plate 7. The interference field 90 thus has a minor influence in the area of ​​the magnetic field sensor 64.

[0108] Figures 15 and 16 depict the same situation as in Figures 13a, 13b and 14a, 14b, with only the magnetic field of magnet 22 being shown with simplified lines. The position of piston 21 in Figure 15 corresponds to the position in Figures 13a, 13b, and the position of piston 21 in Figure 16 corresponds to that in Figures 14a, 14b.

[0109] As can be seen from a combination of Figures 13a, 13b and 14a, 14b as well as Figures 15 and 16, the movement of the piston 21 and thus of the magnet 22 causes a change in the magnetic field lines 9. This is clearly visible in Figures 13a, 13b, 14a, 14b for the magnetic field line 91. In the area of ​​the magnetic field sensor 64, in particular the angle W of the field vector R as well as the length or magnitude of the field vector R change. This change in the field vector R is clearly visible in Figures 15 and 16. It should be noted that the coordinate systems in Figure 10 and the coordinate system in Figures 15 and 16 are not aligned the same. In Figure 10, the y-axis runs along the longitudinal direction of the sensor unit; in Figures 15 and 16, this is the x-axis, but in the opposite direction. The evaluation of the data is the same taking into account the different definitions of the coordinate systems.

[0110] As already explained above, the axial angle in particular changes, so that the angles W1 and W2 shown in the figures essentially correspond to the axial angle. The change in the radial vector is designated R1 and R2 in Figures 15 and 16. This angle or the angle change AW is detected and evaluated using the magnetic field vector 64 and the evaluation unit to obtain information about the position of the piston 21. In some embodiments, the amounts or the change in amount AR are also detected and evaluated.

[0111] Figure 17 shows a flow chart showing how the method according to the invention is carried out, for example, to obtain the above-mentioned information about the position of the piston.

[0112] The magnetic field sensor 64 measures the magnetic flux density in the x, y, and z directions of the Cartesian sensor coordinate system using its sensor element. The obtained values ​​are preferably adjusted based on known inhomogeneities of the sensor. The thus compensated values ​​x', y', z' of the field vector are converted into spherical coordinates M, alpha, and beta. Preferably, the known deviation of the sensor element's position from the zero position is compensated. The compensated spherical coordinates M', alpha', and beta' are rotated so that the coordinate axis M' of the spherical coordinate system runs parallel to the longitudinal center axis Li of the piston 21 and thus to the y-axis of the magnetic coordinate system.

[0113] Because the Hall sensor element is located on the surface of the circuit board in the magnetic field sensor, and because the center plane of the circuit board is located in the sensor axis, the sensor element is spaced from the sensor's rotation axis. This distance is typically half the thickness of the circuit board. Thanks to the radial angle (see Figure 10), rotating the sensor allows the direction of the magnet as seen from the sensor element to be determined. This compensates for the aforementioned distance. This results in compensated spherical coordinates M", "Alpha", and "Beta".

[0114] Preferably, the sensor unit 6 has at least one temperature sensor for measuring the temperature of the sensor unit 6 or for measuring the temperatures of various components or of various areas of the sensor unit 6. Preferably, the temperature of the magnetic field sensor 64 is measured. This measured temperature is preferably taken into account in a further compensation and thus correction of the spherical coordinates. The obtained coordinates are M'", Alpha'" and Beta'". These coordinates or signals can be filtered for the calculation of the piston position (MK'", Alphax"' and BetaK 1"). The output value is the information whether the piston is in the closed state, the open state, or in an intermediate position. The calculation can be performed in different ways. For example, using a lookup table, using polynomial interpolations, and / or using analytical calculations. A zero point adjustment based on determined zero point coordinates MO'", AlphaO'" and BetaO'" is preferably also used to calculate the piston position.

[0115] Preferably, a plausibility check is performed additionally or beforehand by means of filtering to check whether the measured and compensated values ​​are within a specified range (MP'", Alphap'" and Betap'"). If this is not the case, an error message is generated or an error is displayed.

[0116] In the event of a significant deviation of the measured and compensated values ​​from the determined zero point, this indicates that the valve is relatively worn and should be replaced promptly. The device and method according to the invention enable precise determination of the piston position even in confined spaces.

[0117] LIST OF REFERENCE SYMBOLS

[0118] Valve block 632 conductor track

[0119] Inlet channel 64 magnetic field sensor

[0120] Outlet channel 65 heating

[0121] valve chamber

[0122] 67 microcontrollers

[0123] Main valve 68 light-emitting diode (LED)

[0124] valve body

[0125] Piston 7 ring plate

[0126] magnet

[0127] 8 sleeve

[0128] solenoid valve

[0129] Solenoid housing 9 Magnetic field lines electrical connection 90 Interference field

[0130] Conductor coil 91 magnetic field line

[0131] guide tube

[0132] Anchor x, y, z Cartesian sensor

[0133] Retaining ring (Seeger coordinate system

[0134] Ring) M, a, ß Sensor-

[0135] spherical coordinate system

[0136] Inlet line

[0137] Xi, Yi, Zi Cartesian magnetic

[0138] Outlet line coordinate system

[0139] Li longitudinal center axis of the

[0140] Piston sensor unit

[0141] Housing L2 Sensor axis free end area N North pole

[0142] External thread S South Pole

[0143] Window R1 , R2 field vector

[0144] Cable gland W1, W2 angle

[0145] Sensor cable

[0146] Cable end

[0147] circuit board

[0148] passage opening

[0149] copper wall

Claims

PATENT CLAIMS 1. Valve device with a valve which has a movable piston (21) for closing and opening the valve, with a magnet (22) or a magnetizable element and with a sensor unit (6) which has a magnetic field sensor (64) for determining a position of the piston (21), wherein the magnet (22) or the magnetizable element and the sensor unit (6) are movable relative to one another by the movement of the piston (21), wherein the magnetic field sensor (64) is designed to detect an at least two-dimensional vector of a magnetic flux density, characterized in that an evaluation unit is provided which determines an angular change of the at least two-dimensional vector.

2. Valve device according to claim 1, wherein the magnetic field sensor (64) is designed to detect a three-dimensional vector of a magnetic flux density.

3. Valve device according to one of claims 1 or 2, wherein the magnetic field sensor (64) is a 2D Hall sensor or a 3D Hall sensor.

4. Valve device according to one of claims 1 to 3, wherein the magnet (22) or the magnetizable element defines a three-dimensional Cartesian coordinate system with three axes (Xi, Yi, Zi) and wherein the magnetic field sensor (64) is arranged obliquely to the axes (Xi, Yi, Zi).

5. Valve device according to one of claims 1 to 3, wherein the magnet (22) or the magnetizable element defines a three-dimensional Cartesian coordinate system with three axes (Xi, Yi, Zi) and wherein the magnetic field sensor (64) is arranged obliquely to the axes (Xi, Yi, Zi) or is arranged obliquely to at least one of the axes (Xi, Yi, Zi).

6. Valve device according to one of claims 4 or 5, wherein the magnet (22) or the magnetizable element is arranged centrally to a longitudinal center axis (Li) of the piston (21).

7. Valve device according to one of claims 1 to 6, wherein the sensor unit (6) is arranged obliquely to a longitudinal central axis (Li) of the piston (21).

8. Valve device according to one of claims 1 to 7, wherein the valve of the valve device or a second valve of the valve device has a conductor coil (32) generating a magnetic field.

9. Valve device according to claim 8, wherein the conductor coil (32) is arranged in the valve device with a predefined current supply direction.

10. Valve device according to one of claims 8 or 9, wherein a deflection element (7, 8) made of a magnetically conductive material is arranged between the conductor coil (32) and the magnetic field sensor (54).

11. Valve device according to one of claims 1 to 10, wherein the sensor unit (6) has a heater (65) for heating the magnetic field sensor (64).

12. Valve device according to claim 11, wherein the magnetic field sensor (64) is arranged on a first side of a printed circuit board (63) and the heater (65) is arranged on a side of the printed circuit board (63) opposite the first side, wherein the printed circuit board (63) has through openings (630) which extend in the region of the heater (65) from the second side to the first side of the printed circuit board (63), wherein a heat conductor (631), preferably made of copper, is arranged in the through openings (630).

13. Valve device according to one of claims 1 to 12, wherein the sensor unit (6) has a housing (60), wherein the housing (60) has an elongated shape and ends in a free end region (600) and wherein the magnetic field sensor (64) is arranged in the free end region (600).

14. Sensor unit of a valve device according to one of claims 1 to 13, wherein the sensor unit (6) comprises the magnetic field sensor (64) for determining the position of the piston (21), wherein the magnetic field sensor (64) is designed to detect an at least two-dimensional vector of a magnetic flux density, and wherein the sensor unit (6) has an evaluation unit which determines an angular change of the at least two-dimensional vector.

15. A method for determining a position of a piston (21) in a valve device according to one of claims 1 to 13, wherein the magnetic field sensor (64) detects an at least two-dimensional vector of a magnetic flux density and the position of the piston (21) is determined by means of the magnetic field sensor (64), characterized in that the angular change of the at least two-dimensional vector is determined by means of the evaluation unit, wherein the angular change occurs during the movement of the magnet (22) or of the magnetizable element and the sensor unit (6) relative to one another, which movement is generated by the movement of the piston (21).

16. Valve device with a valve which has a movable piston (21) for closing and opening the valve, with a magnet (22) or a magnetizable element and with a sensor unit (6) which has a magnetic field sensor (64) for determining a position of the piston (21), wherein the magnet (22) or the magnetizable element and the sensor unit (6) are movable relative to one another by the movement of the piston (22), characterized in that the sensor unit (6) is arranged obliquely to a longitudinal central axis (Li) of the piston (21).

Images