Device for monitoring a fluid flow

Abstract

A device (10) for monitoring a fluid flow is shown comprising: a lifting body (50) which moves in a straight line depending on the fluid flow, a magnet inserted in the lifting body (50), a measuring cell (30) which is arranged in a fixed position relative to the lifting body (50), wherein the measuring cell (30) is configured to detect the position of the magnet and thus of the lifting body (30) via at least one direction vector of the magnetic field characteristic, and a method for monitoring a fluid flow.

Description

[0001] The invention relates to a device for monitoring a fluid flow according to claim 1 and a measuring method.

[0002] The present invention relates to the field of flow measurement and in particular to a device for monitoring and measuring a fluid flow, such as a gas flow or a liquid flow.

[0003] The invention relates to a flow sensor that is able to measure and monitor the flow velocity and flow rate of a fluid by detecting the position of a lifting body that moves linearly in a measuring tube depending on the fluid flow.

[0004] Various flow sensors are known in the art for monitoring fluid flow. These sensors typically use an array of Hall effect sensors to detect the moving body and determine the flow velocity. Although these sensors are successfully used in many applications, they have some disadvantages. In particular, Hall effect sensors can be sensitive to electromagnetic interference, and their accuracy can be affected by temperature fluctuations. The measurement is often inaccurate, leading to errors in determining the fluid flow.

[0005] From DE 10 2016 004 945 A1, a device for flow measurement is known which uses two Hall sensors to detect the position of a magnet. However, the use of two sensors is disadvantageous because it makes the design more complex and the measurement more prone to errors.

[0006] DE 10 2008 045 177 A1 discloses a method in which the signals of a Hall sensor are calculated into a position signal using a mathematical formula.

[0007] DE 10 2011 115 302 A1 describes a method in which a magnetic field component is corrected by a constant value to reduce distance errors.

[0008] German patent DE 10 2013 222 097 A1 discloses a method that compensates for the influence of temperature on the magnetic field by means of a correction factor. A disadvantage of this method is that it only provides compensation instead of further improving accuracy through targeted evaluation of the best measurement signal ranges.

[0009] Yet another approach is shown in EE 2015 00035 A, in which the measured magnetic field vector is compared with values ​​in a pre-created calibration table (lookup table) to determine the flow rate.

[0010] DE 10 2017 121 789 A1 describes a sensor unit in which the temperature of the magnet is recorded by means of a temperature sensor in order to computationally correct temperature-related fluctuations of the magnetic field based on stored compensation data.

[0011] From JP H06 26900 A, a flow meter is known that uses two magnetic sensors to compensate for fluctuations in magnetic field strength. An angle is calculated from the ratio of the two sensor signals, which is independent of the absolute field strength and represents the position of a float. From DE 10 2021 118 302 A1, a valve with position detection is known in which a magnet is moved past a Hall sensor. To detect a long movement path, several Hall sensors are arranged in series in this solution. However, the use of multiple sensors is more complex in design and increases costs.

[0012] One object of the present invention is to avoid the aforementioned disadvantages of the prior art and to provide a simplified, yet precise and safe device, in particular for detecting small quantities of fluid and a method for monitoring a fluid flow.

[0013] The problem is solved with respect to the device by the characterizing features of claim 1 and with respect to the method by the features of claim 4.

[0014] Advantageous embodiments of the invention are specified in the dependent claims.

[0015] The device according to the invention for monitoring a fluid flow comprises a lifting body that moves linearly depending on the fluid flow, a magnet integrated into the lifting body, and a single measuring cell arranged in a fixed position relative to the lifting body. The measuring cell is configured to detect the position of the magnet, and thus of the lifting body, via at least one direction vector of the magnetic field characteristic. By determining the change in angle, the position of the lifting body can be detected more precisely, resulting in a finer flow measurement.

[0016] It is advantageous if the measuring cell is designed for multidimensional position detection of the magnet. This enables a more precise determination of the lifting body's position and thus more accurate measurement and monitoring of the fluid flow, even at low flow velocities and small deflections of the lifting body. This makes the device versatile and suitable for applications requiring the measurement of small fluid volumes. The multidimensional position detection also allows the device to be used in complex flow conditions.

[0017] Another advantage is that a measurement curve is generated from the measurement signals for each axis (x, y, z). These curves are divided into sections, and the resolution of the measurement signals in each section is evaluated. A reference curve is generated from the sections with the highest resolution, composed of measurement signals from multiple direction vectors. This increases the overall resolution, resulting in more accurate measurements. The more precise data acquisition improves the position determination of the lifting body. This, in turn, enables a more accurate determination of the flow rate, even under changing flow conditions.

[0018] The use of a single measuring cell offers several advantages over conventional Hall sensors and arrangements with multiple sensors: A single measuring cell is less susceptible to electromagnetic interference, and its accuracy is less affected by temperature fluctuations. Using a single measuring cell simplifies the device, resulting in a simpler design and lower manufacturing costs. Furthermore, integrating a single measuring cell is less complex.

[0019] It is advantageous if the measuring cell is an AMR sensor element. An AMR sensor element (anisotropic magnetoresistive sensor) is able to detect the magnetic field of the magnet in the lifting body through the wall of a measuring tube. The magnetic signal is converted into an electrical signal and can then be output via a device. Furthermore, an AMR sensor element enables multidimensional detection of the magnetic field, resulting in improved measurement accuracy.

[0020] It is advantageous for the measuring cell to be temperature-compensated to reduce measurement errors caused by temperature fluctuations. Temperature compensation of the measuring cell helps ensure measurement accuracy under changing temperature conditions, which improves the reliability of the device and enables its applicability in industrial processes with varying operating conditions. Temperature compensation minimizes measurement errors caused by temperature fluctuations, thus improving measurement stability over a wide temperature range. By reducing temperature-related measurement errors, the need for additional temperature control measures is decreased, thereby lowering the development and operating costs of the device.

[0021] The magnet is designed as a permanent magnet, which allows for a simple overall design of the device.

[0022] Furthermore, a method for measuring a fluid flow using the device according to the invention is proposed, comprising the steps of: providing a measuring tube with a movable lifting body therein; detecting the position of the lifting body by means of a measuring cell; calculating the fluid flow based on the detected position of the lifting body.

[0023] In one embodiment, the method further includes a step in which the temperature of the AMR sensor element is monitored and the measurement is temperature-compensated accordingly.

[0024] This method enables direct measurement of fluid flow by detecting the position of the lifting element, allowing for immediate determination of the flow velocity. The use of an AMR sensor element for position detection offers high sensitivity and accuracy in detecting lifting element movements, resulting in more precise flow measurement.

[0025] The invention will now be explained in more detail using exemplary embodiments and with reference to the drawings.

[0026] In the following description of preferred embodiments, identical reference numerals denote identical or comparable components.

[0027] They show schematically: Fig. 1 a flow sensor according to the invention; Fig. 2 a cross-sectional view through a flow sensor; Fig. 3 the graphical representation of a measurement signal during a change in the position of the magnet along a linear axis.

[0028] Fig. Figure 1 schematically shows a flow sensor according to the invention consisting of a measuring unit 100 and a measuring section 200, each of which has its own housing and can be connected to each other.

[0029] Fig. Figure 2 shows a cross-sectional view through the flow sensor according to Fig. 1. The measuring unit 100 comprises a sensor element, in particular an AMR measuring cell 30 or GMR measuring cell for detecting a magnet inserted into a lifting body 50, thereby generating measurement signals. An AMR measuring cell, also known as an anisotropic magneto-resistance (AMR) measuring cell, utilizes the AMR effect to measure magnetic fields. Compared to GMR, an AMR measuring cell is less expensive and easier to manufacture. The AMR effect is based on the change in electrical resistance in ferromagnetic materials depending on the direction of the current relative to the direction of magnetization. When the current flows parallel to the direction of magnetization, the resistance is lower than when the current flows perpendicular to it.AMR sensors, which operate three-dimensionally and are capable of measuring magnetic fields along all three spatial axes x, y, and z, combine resistance measurement in a single AMR sensor cell to enable complete three-dimensional magnetic field acquisition. This allows the direction and strength of the magnetic field to be read out along multiple axes, increasing the overall measurement accuracy. A GMR sensor cell, also known as a Giant Magneto-Resistance (GMR) sensor cell, utilizes the GMR effect to measure magnetic fields. The GMR effect is based on the change in electrical resistance in magnetic materials when exposed to an external magnetic field. A GMR sensor measures the change in electrical resistance caused by an external magnetic field. This change in resistance is converted into an electrical signal that reflects the strength and direction of the magnetic field.Furthermore, a carrier contains 80 circuit structures and electronic components for processing the measurement signals, and an interface S is located laterally, which supplies the measuring unit 100 with power and via which communication with a higher-level control unit takes place. The lifting element 50 is movably arranged within a measuring tube 40 within the measuring section 200. If a fluid flows through the measuring section, the lifting element is driven by this fluid and moves in the direction of the arrow. This movement is detected as an angular change by a measuring cell 30.

[0030] Fig. Figure 3 shows a graphical representation of the measurement signal during a change in the position of the magnet along the guide axis of the lifting body 50. The measuring cell 30 is configured to detect the position of the magnet of the lifting body 50 along the spatial axes x, y, and z. This eliminates the need to specifically align the magnet with the measuring cell 30. Even if the measuring cell 30 happens to coincide with one of the magnetic axes, thereby distorting the measurement for that axis, the measurements for the other axes remain unchanged. These two remaining axes continue to provide usable measurement signals that can detect the movement of the magnet. The flow sensor 10 thus ensures reliable and safe position determination of the magnet. By subdividing the measurement curves x-axis, y-axis, z-axis into sections, see Figure 3. Fig.3. An evaluation of these areas regarding the resolution of the measurement signals can be performed. A reference curve is then created from the areas with the highest resolution, composed of measurement signals from multiple direction vectors. This procedure leads to a higher overall resolution of the measurement data. The higher resolution enables more precise measurements. The improved accuracy helps to optimize the position determination of the lifting body 50. This, in turn, allows for a more accurate determination of the flow rate.

[0031] The flow sensor 10 according to the invention can be used in various applications where precise measurement of fluid flows is required. Examples of such applications include monitoring air flows in ventilation and air conditioning systems, measuring gas flows in industrial processes, and monitoring liquid flows in pipelines.

[0032] The invention provides a precise, scalable, and versatile device 10 for monitoring a fluid flow. Due to its high sensitivity, the device 10 can be used particularly for detecting small quantities of fluid. Overall, the device 10 consists of few individual parts and has a simple design, which reduces manufacturing costs.

[0033] The use of a single AMR measuring cell designed for multidimensional acquisition simplifies the construction of the device 10 and leads to a more compact design, which increases the possibilities for use in confined installation conditions. Reference symbol list 10 flow sensors 30 measuring cells 40 measuring tube 50 lifting bodies 80 carriers 100 measuring units 200 measuring section S interface x Measurement curve, x-axis y-measurement curve, y-axis z-axis measurement curve

Claims

[1] Device (10) for monitoring a fluid flow, comprising: a lifting body (50) which moves in a straight line depending on the fluid flow, a magnet inserted in the lifting body (50), a measuring cell (30) which is arranged in a fixed position relative to the lifting body (50), characterized by , that the measuring cell (30) is set up for multidimensional detection of the position of the magnet in order to generate measurement signals for several axes (x, y, z), and that the device (10) includes an evaluation unit which is set up to a) to divide the measurement curves (x, y, z) generated from the measurement signals into areas, b) to carry out an assessment of the resolution of the measurement signals for each area, and c) to generate a reference curve from the areas with the highest resolution, which is composed of measurement signals of several direction vectors. [2] Device (10) according to claim 1, characterized by , that the measuring cell (30) is an AMR sensor element. [3] Device (10) according to claim 1 or 2, wherein the measuring cell (30) is temperature compensated to reduce measurement errors due to temperature fluctuations. [4] Method for monitoring a fluid flow using a device (10) according to any one of the preceding claims, comprising the steps: - Providing a measuring tube (40) with a movable lifting element (50) therein; - Determining the position of the lifting body (50) using a measuring cell (30); - Calculating the fluid flow based on the detected position of the lifting body (50), the calculation comprising the following steps: a) Dividing the measurement curves (x, y, z) generated from the measurement signals of the measuring cell (30) into areas, b) Conducting an assessment for each area regarding the resolution of the measurement signals, and c) Generating a reference curve from the areas with the highest resolution, composed of measurement signals from several direction vectors. [5] Method according to claim 4, wherein the method further comprises a step in which the temperature of the measuring cell (30) is monitored and the measurement is temperature compensated accordingly.

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