AT519061B1 - volume meter - Google Patents

Abstract

Volume meter, comprising at least two intermeshing, rotatable volumetric flow measuring means (6, 9) each having a rotation axis (4, 4a) arranged in a measuring chamber, at least one permanent magnet (2) and at least one sensor (1), wherein the permanent magnet ( 2) is diametrically magnetized and axially on the axis of rotation (4, 4a) of the volumetric flow measuring means (6, 9) is arranged and connected thereto; the sensor (1) is arranged in the axial extension of the axis of rotation (4, 4a) over the permanent magnet (2); and the sensor (1) is a Hall sensor, which is designed as a Hall sensor array that detects a rotation angle change and operates without contact.

Description

Description THE INVENTION CONCERNS A VOLUME COUNTER.

In order to measure highly viscous media reliably, volumetric gear measuring cells or spindle measuring cells are used in practice. In order to reduce the pressure losses with highly viscous media, the measuring cells are mechanically oversized. However, this greatly reduces the resolution.

The most common field of use is for measuring process fluids for high viscosity media such as e.g. Paints and varnishes, as used in body painting. Of course, other materials can also be measured, e.g. Resins and adhesives, food. Furthermore, these are used for exact dosing tasks.

Mostly volumes are measured. Here the value of the volume flow is integrated. Over time you get the funded volume. Another option is to measure the current flow value. The process-reliable measurement of the current flow value represents a challenge with the current systems according to the prior art, since the values often fluctuate around the real measured value. For the measurement of the total volume delivered, this fluctuation poses a problem with small volumes because of too few integrated flow values and a large fluctuation range of these. As the volume increases, the measurement error becomes smaller, since there are several flow values for the measurement data processing.

The systems for volume measurement according to the prior art, gear counter and screw spindle counter or spindle counter, displace the fluid to be measured from the space in the cells and move the gears or spindles in motion. Depending on the size and design, the displacement per revolution is decisive for the volume measurement. A sensor absorbs the revolutions or current speed of the gears or spindles. The systems are under high pressure (up to 400 bar). For this reason, the rotary axis ends are not guided to the outside. This has the implication that so the axial bearing forces are minimized and no shaft seals are necessary. It eliminates the increased friction in the bearings and the seals. Preferably, the current rotational speeds of the axes of rotation are detected contactlessly via sensors. The sensor system depends on the type and manufacturer. The flow rate or the volume is calculated as follows: [0005] Current flow = current speed x displacement volume / revolution [0006] Conveyed volume = number of revolutions x displacement volume / revolution The volume measured is thus an integration of the individual flow values over the Time. For very short measurements, the deviation is higher than for longer measurements (larger volumes), because the error of the wrong current flow values is not so significant.

The prior art systems mainly measure volume by integrating the flow. However, according to the inventors' measurements, the real-time flow values oscillate sinusoidally around the real value. Deviations of 10% and more are possible when determining the current flow. This is caused by the sensors used, which detects the speed or rotational angle information of the gear or the spindle. In most cases, measured values are interpolated and intermediate values are calculated in order to achieve a higher resolution, but these values are very heavily error-prone.

GEAR COUNTER

Attention is paid to the teeth of the measuring cells by means of two inductive sensors (axially off-center at the edge of the toothed wheel) (see, for example, VSE Volumenttechnik GmbH, US2009 / 0293637 A1). By counting the teeth is calculated on the current flow. An improved possibility is the calculation of intermediate values. It is measured with the sensor, how far the tooth is pushed in front of the sensor. These measured values are processed and digitized. An interpolation of currently 16 times can be made possible (one tooth is interpolated to 16 individual signals). However, this measurement is highly dependent on how the sensor is aligned with the gears. In addition, the resolution depends on the number of teeth. Furthermore, the measured value can fluctuate if the gear wheel is mounted eccentrically on the shaft, has a shock or the teeth are not precisely manufactured.

COP COUNTER

A measuring gear or increment disc is mounted on one of the spindles. A sensor is radially aligned with the face of the gear / increment disc and counts the teeth / increments. The interpolation and the concept are the same as with a gear counter.

In another spindle counter magnets are mounted on one end of a measuring spindle on the circumference. A sensor, which sits radially to the axis of rotation, measures the magnetic fields, which are rotated past. Here also a higher resolution can be achieved by means of interpolation. As described above, however, the current flow values fluctuate around the measuring range due to tolerances (eccentric axis of rotation, unequal magnetic field, incorrectly aligned sensor on the axis of rotation).

MESSKONZEPT

Two offset by 90 ° sensors generate a sine and a cosine signal from the tooth geometry. From these, the tangent is calculated or a space vector is generated. A block calculates the tangent. The problem here is an erroneous detection of the sine and cosine signal and the resulting space pointer (if the sensor, which receives the cosine, is not offset by exactly 90 ° to the sine-wave sensor, a false tangent is calculated). Furthermore, the resolution is limited. It can increase the number of teeth, but the sampling of the gear is faulty.

EP 1994375 B1 describes a volume measuring device having intermeshing tooth elements, wherein a non-contact measuring sensor for movement detection of the Verzahnungselements is provided and the volume measuring device generates at least a cosine and sinusoidal signal, wherein the sensor detects a change in angle of magnetic field lines and after an MR principle or AMR principle works, wherein a sensor associated with the magnetic field generating means is a diametrical magnet having at least two poles and is arranged in a cavity of a shaft of a toothed element. By describing the MR or AMR principle, it will be explained how a cosine and sinusoidal signal is generated by the probe. For the person skilled in the art working sensors according to the MR or AMR principle are known, which output two mutually offset by 90 ° sinusoidal signals. The sensor according to the MR principle or AMR principle is arranged axially to the toothed element. The sensor has a resolution of half a revolution of the toothed element. It is mentioned that an additional measuring sensor can be arranged eccentrically to the toothed element, in order to obtain additional measuring information, whether it is still the first half turn or even the second half turn of the toothed element. Here, for example, a non-specific Hall sensor or a flip-flop circuit is given. A connection between Hall sensor and axial alignment on the axis of rotation of the toothed element is not established; it is held on the MR or AMR sensor as an axial sensor.

US2008178687A1 describes an axial flow meter with two spindles. As a sensor, only a single sensor is listed, which can be designed as a Hall sensor.

DE29607736U1 describes a device for dosing and measuring quantities of liquid. As a sensor, a magnetic sensor, such as a Hall element, is provided. Furthermore, it is described that a pole wheel sits on the axis of the spindle, wherein the pole wheel has four magnets.

EP0858585B1 describes a device for measuring quantities of liquid with two intermeshing screw spindles which can be flowed through in the axial direction, wherein the arrangement of at least two Hall sensors is off-center with respect to the axis of rotation of a screw spindle, wherein the magnet is also arranged off-center on a disk.

JPH0712613A describes a flow meter, wherein only a Hall sensor is described by way of example.

DE102010053166A1 describes a flow meter with screw spindles and a sensor element which emits a signal dependent on the angle of rotation of one of the screw spindles. The screw spindle is made ferromagnetic. The permanent magnet (it is not stated if it is diametrically magnetized) and the two Hall sensors are arranged laterally of the screw spindle and not axially.

US2005039546A1 describes a low-cost flow meter with a rotating component in the inner part. The arrangement of three Hall sensors on the side of the turbine is described. Furthermore, it is described that a magnet is arranged in the sensor, wherein a field between sensor and steel rotor is constructed. If the rotor is not made of steel, a steel ring must be pressed onto the rotor.

DE102014115663A1 describes a spindle flow meter with parallel recesses in which screw spindles are arranged, wherein two sensors are provided laterally to a screw spindle. These sensors may be, for example, Hall sensors.

The aim of the invention is the exact detection of the angle of rotation of the axes of rotation, which are driven by intermeshing toothed elements, and an improvement in the measurement of the axes of rotation driven by the media. The mechanical system is considered optimal without losses due to leakage or backflow.

In order to achieve an improvement in the measured values, the aim is to detect the rotation angle as accurately as possible. This information can be used to recalculate the current flow rate and the resulting volume delivered. In addition, absolute rotation angle information is beneficial. Based on this information, the measuring means is exactly coupled within one revolution with an angle information.

According to the invention this is achieved by a volumeter is provided comprising at least two intermeshing, rotatable Volumenstrommessmittel each having an axis of rotation, which are arranged in a measuring chamber, at least one permanent magnet and at least one sensor, wherein the permanent magnet is diametrically magnetized and is disposed axially on the axis of rotation of one of the volumetric flow measuring means and is connected thereto; the sensor is arranged in the axial extension of the axis of rotation above the permanent magnet; and the sensor is a Hall sensor, the Hall sensor is designed as a Hall sensor array that detects a rotation angle change and operates without contact.

A magnet is axially fixed to a rotary axis end of the volumetric flowmeter. A sensor is arranged in the axial extension of the axis of rotation, which is coupled via a magnet without contact with the axis of rotation of the volume flow measuring means. Due to this structure, a maximum resolution can be assumed. Bidirectional operation is possible (the flow direction is detectable).

The diametral magnetization of the permanent magnet means that the north and south poles are arranged opposite each other with respect to the axis of rotation, i. E. the permanent magnet has the shape of a cylinder and the boundary between the north and south pole passes through the center of the base or top surface and divides the cylinder into two equal-sized half cylinders. If the axis of rotation of the volume flow measuring means rotates, the permanent magnet rotates with and with it the magnetic field, whereby a measurement of the speed is possible. This represents an extremely advantageous possibility of measuring the revolution of the volume flow measuring means and thus a possibility of calculating the volume flow. It is also possible to use a diametral magnet with more than 2 poles.

The volumetric flow measuring means are installed in the measuring chamber. The measuring chamber is installed in the barrel housing.

If a simple Hall sensor flows through a current and placed in a perpendicular magnetic field, it provides an output voltage which is proportional to the product of magnetic flux density and current (Hall effect). The signal is also temperature dependent and can have an offset.

A Hall sensor also provides a signal when the magnetic field in which it is located is constant. This is the decisive advantage compared to a sensor consisting of magnet and coil. As soon as the magnet and the coil are not moved relative to one another in this pairing, the voltage induced in the coil is zero and the magnet is not recognized. Another important advantage of Hall sensors is that they do not require magnetically active materials (such as nickel or iron) to be realized. Thus, the magnetic field to be measured is not already changed by bringing the sensor into it. Magnetoresistive sensors or flux gate sensors do not have this feature. Only the operating current of the Hall element generates a small additional magnetic field which is superposed additively to the magnetic field to be measured. However, this does not produce any hysteresis or saturation effects that are unavoidable in magnetically active materials. The Hall sensor works according to the galvanomagnetic effect, in contrast to MR or AMR sensors, which work according to the magneto-resistive effect.

The Hall sensor array is the sensor element which detects the magnetic field of the diametrically magnetized magnet. In a Hall sensor array several Hall sensors are placed in an exact position to each other. In the case of a rotation angle sensor, these are arranged in a circle around the center of rotation. An integrated circuit is used to measure the individual Hall voltages and to convert them into an absolute angular position using analogue / digital conversion. This information can be output as a sine-cosine signal, as a single pulse, or as an absolute position or angular position, depending on the chipsets and interfaces used.

A Hall sensor array may consist of several Hall sensors, which are mounted in a specific position. A Hall sensor array can be purchased as a finished chipset in the trade.

In one embodiment, a pressure-resistant partition between the measuring chamber and the sensor may be arranged. As a result, the sensor is decoupled from the measuring chamber and is located outside the fluid area. The sensor is also decoupled from the delivery pressure by the pressure-resistant partition. Thus, the sensor does not have to be pressure-resistant.

In one embodiment, the flameproof partition may be non-magnetic. As a result, it does not interfere with the permanent magnet.

In another embodiment of the invention, each sensor may be associated with each volumetric flow meter. Thus, each volumetric flow meter can be measured individually. Any irregularity between the volumetric flow measuring means can be noticed and corrected by the accurate measurement by the sensor.

In one embodiment of the present invention, the axes of rotation of the rotary volumetric flow measuring means may be arranged perpendicular to the flow direction of the fluid. As a result, the volumetric flow measuring medium is flowed radially and is thereby set in a rotary motion.

In one embodiment of the present invention, the volumetric flow measuring means may be gears. Gears are a widely used volume flow meter in volumetric flow measurement and are ideal for measuring volumetric flows. The term "gear" is broadly defined herein and includes not only gears with invariable teeth, but also gears with variable, usually length-adjustable, teeth, such as vanes, such as those used in vane pumps or rotary vane pumps, vane cells in this case two teeth that are adjustable in length.The number of teeth is not limited to a specific number.

In another embodiment of the present invention, the axes of rotation of the rotary volumetric flow measuring means may be arranged parallel to the flow direction of the fluid. As a result, the volumetric flow measuring medium is flowed axially and is thereby set in a rotary motion.

In one embodiment of the present invention, the volumetric flow measuring means may be screw spindles. Screw spindles are a widely used volume flow measuring device in volumetric flow measurement and are ideal for measuring volumetric flows.

In one embodiment of the present invention, the sensor may be hermetically separated from the fluid volume and / or disposed outside the measurement chamber. The flow cell can be made more compact, and the sensor can be easily removed, if there is no longer a need for a measurement, without affecting the remaining structure of the measuring chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows an embodiment of a volume meter according to the invention in

Shape of a gear counter.

FIG. 2 shows an embodiment of a volume counter according to the invention in FIG

Shape of a spindle counter.

Fig. 3 shows a magnet which is magnetized diametrically.

The reference numerals mean: 1: sensor - axially arranged about axis of rotation 2: permanent magnet 3: magnetic retaining pin (non-ferromagnetic) / connected with bearing pin via press fit 4, 4a: axis volume flow measuring 5: sliding bearing on the sensor side 6: volumetric flow sensor side 7: plain bearing bottom 8th : Gland plate 9: Volumetric flow meter 10: Bearing housing 11: Gasket 12: Sensor housing 13: Pressure housing 14: Bearing main spindle 15: Bearing main spindle 16: Bearing slave spindle 17: Bearing slave spindle

EXAMPLES

Example 1 - gear counter with Hall sensor (not according to the invention) The volume meter comprises at least two intermeshing, rotatable gears 6, 9, which constitute the volume flow measuring means 6, 9, each having a rotation axis 4, 4a, in a measuring chamber are arranged, at least one permanent magnet 2 and at least one sensor 1, wherein the permanent magnet 2 is diametrically magnetized and is arranged axially on the axis of rotation 4 of the gear 6 and connected thereto; the sensor 1 is arranged in the axial extension of the rotation axis 4 above the permanent magnet 2; and wherein the sensor 1 is a Hall sensor which detects a rotation angle change and operates without contact.

A magnet 2 is axially fixed to a rotation axis end of the gear 6. A sensor 1 is arranged in the axial extension of the axis of rotation 4, which is coupled via a magnet 2 without contact with the axis of rotation 4 of the gear 6. Due to this structure, a maximum resolution can be assumed. Bidirectional operation is possible (the flow direction is detectable).

The diametral magnetization of the permanent magnet 2 means that north and south poles are arranged opposite to each other with respect to the rotation axis 4, i. the permanent magnet 2 has the shape of a cylinder and the boundary between the north and south pole passes through the center of the base or top surface and divides the cylinder into two equal-sized half-cylinder. Rotates the axis of rotation 4 of the gear 6, the permanent magnet 2 rotates with and with it the magnetic field, whereby a measurement of the speed is possible. This represents an extremely advantageous possibility of measuring the rotation of the gears 6, 9 and thus a possible calculation of the volume flow. A diametrically magnetized permanent magnet 2 is shown in FIG.

The permanent magnet 2 can also be arranged above the axis of rotation 4 a of the gear 9. Likewise, a permanent magnet 2 can be arranged both above the axis of rotation 4 of the toothed wheel 6 and above the axis of rotation 4a of the toothed wheel 9. The remaining details of such an arrangement may be as described above.

The axes of rotation of the gears 6, 9 are arranged perpendicular to the flow direction of the fluid. An embodiment is shown in FIG. The gears 6, 9 are flowed radially and are thereby placed in a rotary motion.

It can be arranged a pressure-resistant partition between the measuring chamber and the sensor 1. As a result, the sensor 1 is decoupled from the measuring chamber and is located outside the fluid area. The sensor 1 is decoupled from the discharge pressure by the flameproof partition. Thus, the sensor does not have to be pressure resistant.

The flameproof partition may be non-magnetic. As a result, it does not interfere with the permanent magnet.

It can be assigned to each volume flow measuring a sensor 1. Thus, each volumetric flow meter can be measured individually. Any irregularity between the volumetric flow measuring means can be noticed and corrected by the accurate measurement by the sensor 1.

The sensor 1 may be hermetically separated from the fluid volume and / or arranged outside the measuring chamber. The measuring chamber can thus be made more compact, and the sensor 1 can be easily removed, if there is no longer a need for a measurement, without affecting the remaining structure of the measuring chamber.

The gears 6, 9 may also be gears with variable, usually adjustable in length, teeth, e.g. Vane cells, such as those used in vane pumps or rotary vane pumps; Vane cells in this case have two teeth that are variable in length. However, the number of teeth is not limited to a certain number.

The sensor 1 is a Hall sensor. It can be the exact and absolute position of the axis of rotation and thus the exact and absolute position of the position of the gears are determined, thereby the exact volume can be determined. The structure is largely insensitive to positioning of the sensor 1 (this can easily be off-centered, without falsifying the measurement result). Thus, there is the possibility that the volume measuring cell can be calibrated and theoretically the delivery volume of each individual tooth can be defined.

Example 1b - Gear Counter with Hall Sensor Array Starting from the volume counter in Example 1, the Hall sensor can be designed as a Hall sensor array, which detects a rotation angle change and operates without contact. A Hall sensor array is an array of many individual Hall sensors, which in the case of a rotation angle sensor are arranged in a circle around the center. This large number of Hall sensors as a Hall sensor array allows even more accurate resolution of the absolute position of the gears. With the Hall sensor array, a resolution of up to 14 bits (16384 pulses / revolution) can be achieved with the current state of the art. The more Hall sensors in the array, the higher the resolution.

Example 2 - spindle counter with Hall sensor (not according to the invention) The volume meter comprises at least two intermeshing, rotatable screw spindles or spindles 6, 9, which constitute the volume flow measuring means 6, 9, each having a rotation axis 4, 4a which are arranged in a measuring chamber, at least one permanent magnet 2 and at least one sensor 1, wherein the permanent magnet 2 is diametrically magnetized and is arranged axially on the axis of rotation 4 of the screw 6 and connected thereto; the sensor 1 is arranged in the axial extension of the rotation axis 4 above the permanent magnet 2; and wherein the sensor 1 is a Hall sensor which detects a rotation angle change and operates without contact.

A magnet 2 is axially fixed to a rotary shaft end of the screw shaft 6. A sensor 1 is arranged in the axial extension of the axis of rotation 4, which is coupled via a magnet 2 without contact with the axis of rotation 4 of the screw 6. Due to this structure, a maximum resolution can be assumed. Bidirectional operation is possible (the flow direction is detectable).

The diametral magnetization of the permanent magnet 2 means that north and south poles are arranged opposite to each other with respect to the rotation axis 4, i. the permanent magnet 2 has the shape of a cylinder and the boundary between the north and south pole passes through the center of the base or top surface and divides the cylinder into two equal-sized half-cylinder. Rotates the axis of rotation 4 of the screw 6, the permanent magnet 2 rotates with and with it the magnetic field, whereby a measurement of the speed is possible. This represents an extremely advantageous possibility of measuring the revolution of the screw spindles 6, 9 and thus a possible calculation of the volumetric flow. A diametrically magnetized permanent magnet 2 is shown in FIG.

The permanent magnet 2 can also be arranged above the axis of rotation 4a of the screw spindle 9. Likewise, a permanent magnet 2 can be arranged both above the axis of rotation 4 of the screw spindle 6 and above the axis of rotation 4a of the screw spindle 9. The remaining details of such an arrangement may be as described above.

The axes of rotation of the screw spindles 6, 9 are arranged parallel to the flow direction of the fluid. An embodiment is shown in FIG. The screw spindles 6, 9 are flowed axially and are thereby set in a rotary motion.

It may be arranged a pressure-resistant partition between the measuring chamber and the sensor 1. As a result, the sensor 1 is decoupled from the measuring chamber and is located outside the fluid area. The sensor 1 is decoupled from the discharge pressure by the flameproof partition. Thus, the sensor does not have to be pressure resistant.

The flameproof partition may be non-magnetic. As a result, it does not interfere with the permanent magnet.

It can be assigned to each volume flow measuring a sensor 1. Thus, each volumetric flow meter can be measured individually. Any irregularity between the volumetric flow measuring means can be noticed and corrected by the accurate measurement by the sensor 1.

The sensor 1 can be hermetically separated from the fluid volume and / or arranged outside the measuring chamber. The measuring chamber can thus be made more compact, and the sensor 1 can be easily removed, if there is no longer a need for a measurement, without affecting the remaining structure of the measuring chamber.

The sensor 1 is a Hall sensor. It can be the exact and absolute position of the axis of rotation and thus the exact and absolute position of the position of the spindle can be determined, thereby the exact volume can be determined. The structure is largely insensitive to positioning of the sensor 1 (this can easily be off-centered, without falsifying the measurement result). Thus, there is the possibility that the volume measuring cell can be calibrated and theoretically the delivery volume of each individual chamber generated in the spindle can be defined.

Example 2b - spindle counter with Hall sensor array

Starting from the volume counter in Example 2, the Hall sensor can be designed as a Hall sensor array, which detects a rotation angle change and operates without contact. A Hall sensor array is an array of many individual Hall sensors, which in the case of a rotation angle sensor are arranged in a circle around the center. This large number of Hall sensors as Hall sensor array allows an even more accurate resolution of the absolute position of the spindle. With the Hall sensor array, a resolution of up to 14 bits (16384 pulses / revolution) can be achieved with the current state of the art. The more Hall sensors in the array, the higher the resolution.

Claims (9)

claims 1. Volumenzähler, comprising at least two intermeshing, rotatable volume flow measuring means (6, 9), each having an axis of rotation (4, 4a), which are arranged in a measuring chamber, at least one permanent magnet (2) and at least one sensor (1), characterized in that the permanent magnet (2) is diametrically magnetized and is arranged axially on the axis of rotation (4, 4a) of one of the volumetric flow measuring means (6, 9) and is connected thereto; the sensor (1) is arranged in the axial extension of the axis of rotation (4, 4a) over the permanent magnet (2); and the sensor (1) is a Hall sensor, which is designed as a Hall sensor array that detects a rotation angle change and operates without contact. 2. Volume meter according to claim 1, characterized in that a pressure-resistant partition wall between the measuring chamber and the sensor (1) is arranged. 3. Flow meter according to claim 2, characterized in that the flameproof partition is non-magnetic. 4. Volume meter according to one of the preceding claims, characterized in that each volume flow measuring means (6, 9) is associated with a sensor (1). 5. Volume meter according to one of the preceding claims, characterized in that the axes of rotation (4, 4a) of the rotary volumetric flow measuring means (6, 9) are arranged perpendicular to the flow direction of the fluid. 6. volumeter according to claim 5, characterized in that the volume flow measuring means (6, 9) are gears. 7. volumeter according to one of claims 1 to 4, characterized in that the axes of rotation (4, 4a) of the rotary volumetric flow measuring means (6, 9) are arranged parallel to the flow direction of the fluid. 8. volumeter according to claim 7, characterized in that the volume flow measuring means (6, 9) are screw spindles. 9. Volume meter according to one of the preceding claims, characterized in that the sensor (1) is hermetically separated from the fluid volume and / or is arranged outside the measuring chamber. For this 3 sheets of drawings