Device for measuring the flow rate of a liquid

Abstract

The present disclosure relates to a device (100; the utility model relates to an apparatus (100, 200) for selectively opening and closing a flow channel (1a), comprising a flow channel (1a), a valve (7) for selectively opening and closing the flow channel (1a), and a measuring unit (20) configured to determine, after the valve (7) has closed the flow channel (1a), a time [Delta] t taken for a liquid fed to the flow channel (1a) above the valve (7) to rise to an upper predetermined liquid level (10a) in the flow channel (1a).

Description

Technical Field

[0001] The subject matter of the present disclosure relates to a device for measuring the flow rate of a liquid. Devices of this type can be used in the field of mechanical engineering, and in particular in the field of hydraulics. Background Art

[0002] In the hydraulic field, it is common practice to measure the flow rate of a hydraulic medium flowing into or out of a hydraulic unit, such as a hydraulic pump / motor or a hydraulic cylinder, in order to evaluate the performance of the unit and its efficiency. Known devices for measuring flow rate are usually connected to the hydraulic unit via a flow channel (e.g. a pipe) of specific dimensions, and the fluid passing through the flow rate measuring device usually generates a pressure drop, which may depend on the velocity of the fluid. For this reason, the hydraulic unit whose flow rate is intended to be measured usually generates a certain hydraulic pressure and maintains this pressure for a certain flow rate. However, some hydraulic units may not meet this requirement.

[0003] Known devices for measuring flow rate include, for example, turbines, gears, differential pressure devices, vortex devices, and mass flow meters. In the prior art, various methods and devices for measuring the flow rate of a liquid are used.

[0004] For example, US Pat. No. 9,410,833 B1 discloses a fluidic device for measuring the flow rate of water using an ultrasonic measuring system.

[0005] US 7,080,551 B2 discloses a measuring device for measuring flow rate using bubbles in a liquid, the bubbles moving with the liquid in a transparent passage, wherein the flow rate can be obtained by measuring the velocity of the bubbles.

[0006] US 3,580,092 discloses a clamp-on device for measuring flow rate which detects ultrasonic radiation in a pipe generated by the shearing action of a fluid flowing in the pipe.

[0007] Depending on the specific type of device used for flow rate measurement, several factors are generally considered, such as:

[0008] Fluid type, fluid viscosity, device connection type, pipe size, process temperature (minimum and maximum), range of flow rates to be measured (minimum and maximum), pressure range (minimum and maximum), desired accuracy range, and potential additional parameters that may depend on the specific application.

[0009] In any case, most known devices for measuring flow rate, especially so-called "invasive" devices, usually introduce an obstruction, increasing the pressure of the fluid upstream of the obstruction. In many applications, this can interfere with the measurement and affect the accuracy of the measurement.

[0010] Another type of device for measuring flow rate is a clamp-on device that is attached to the outside of a pipe to measure flow rate. However, in order to obtain reliable measurements, the pipe size and flow rate are usually within a specific operating range. For example, this type of flow meter usually does not allow for reliable measurements at very low flow rates or when measuring the flow rate of pulsating flows. Utility Model Content

[0011] Considering the background of the art of flow rate measurement, there is a need for a device which allows the flow rate of a liquid to be measured without being restricted by the specific dimensions of the pipe and which can be applied to systems with low or very low flow rates and to systems with pulsating flows.

[0012] This need is met by a device for measuring liquid flow rate comprising the following features.

[0013] Currently proposed devices for measuring liquid flow rate include:

[0014] Flow channel,

[0015] a valve for selectively opening and closing the flow passage, and

[0016] A measuring unit is configured to determine the time Δt taken for liquid fed to the flow channel above the valve to rise to an upper predetermined level in the flow channel after the valve has closed the flow channel.

[0017] In the context of the present disclosure, liquid may include or may consist of any type of material that flows under the influence of gravity, including liquids, in particular hydraulic liquids, possibly also gases or materials like sand or generally materials that are able to trickle.

[0018] The present disclosure relates generally to a device for measuring flow rate for hydraulic applications, which can measure the flow rate without introducing a pressure drop. This generally allows the flow rate to be measured also at very low pressures or in pipes or conduits that cannot withstand high pressures.

[0019] For example, the currently proposed device for measuring flow rate can be configured to be connected to various units that cannot generate huge pressure levels. The device for measuring flow rate can be independent of the pipeline size, and it can be used in systems with a flow rate close to zero, such as for measuring leakage rates and for measuring pulsating flows. For example, the currently proposed device for measuring flow rate can be integrated into a pipeline or pipeline. Additionally or alternatively, the currently proposed device for measuring flow rate can be adopted as an external device. For example, the currently proposed device for measuring flow rate can be activated and used as required. Generally, the device does not introduce mechanical wear.

[0020] For example, the device may be used to measure a wide range of flow rates, such as by adding one or more connected devices in series and thereby increasing the volume of the flow channel without affecting measurement accuracy.

[0021] The flow channel including the section in which the level detection device may be located may have different shapes or cross-sections, including circular, elliptical or polygonal cross-sections.

[0022] Devices according to the present disclosure may allow for the measurement of liquid flow independent of the viscosity of the liquid or its temperature.

[0023] One example of an application of the device according to the present disclosure is the measurement of internal leakage of a hydraulic spool valve. The internal leakage flow rate is close to zero and the pipe cannot withstand pressure. Therefore, it may be necessary or advantageous to use a non-invasive method. The device according to the present disclosure solves this problem and the measurement is performed by an automatic system, which will be described in more detail below.

[0024] The measuring unit is typically configured to determine the flow rate q of the liquid fed to the flow channel above the valve according to q=ΔV / Δt, wherein ΔV is the known volume of the portion of the flow channel through which the liquid rises to the upper predetermined liquid level. For example, ΔV may account for at least 50%, at least 70%, or at least 90% of the section of the flow channel extending from the valve to the upper predetermined liquid level.

[0025] The measuring unit may include an upper liquid level detection device configured to determine whether the liquid level in the flow channel has reached an upper predetermined liquid level. The upper liquid level detection device may be arranged outside the flow channel, for example, near the flow channel. For example, the measuring unit may be configured to determine whether the liquid level in the flow channel has reached an upper predetermined liquid level based on a time point t U At, ie the time it takes for liquid fed into the flow channel above the valve to rise to a predetermined upper level in the flow channel, is determined.

[0026] The measuring device may further include a lower liquid level detection device configured to determine whether the liquid level in the flow channel has reached a lower predetermined liquid level disposed at the valve or disposed between the valve and the upper predetermined liquid level. The lower liquid level detection device may be disposed outside the flow channel, for example, near the flow channel. For example, the measuring unit may be configured to further determine whether the liquid level in the flow channel has reached a lower predetermined liquid level based on a time point t at which the liquid level reaches the lower predetermined liquid level. L In the case where the lower predetermined liquid level is set at or defined by the position of the valve, t L The time point at which the valve closes and the liquid level in the flow channel begins to rise above the valve is given. More specifically, the measuring unit can be configured according to Δt=t U -t L Determine Δt.

[0027] One or both of the upper liquid level detection device and the lower liquid level detection device may not be configured to measure the liquid level in the flow channel above the valve independently of its position. Instead, one or both of the upper liquid level detection device and the lower liquid level detection device may be configured to detect the liquid level only when or once the liquid level reaches or has reached the upper predetermined liquid level and / or the lower predetermined liquid level, respectively. That is, the upper liquid level detection device may be configured to provide binary "yes / no" information indicating whether the liquid level in the flow channel above the valve has reached the upper predetermined liquid level. And, the lower liquid level detection device may be configured to provide binary "yes / no" information indicating whether the liquid level in the flow channel above the valve has reached the lower predetermined liquid level.

[0028] The upper liquid level detection device and / or the lower liquid level detection device may include, for example, at least one of a liquid sensor, a known type of float switch, a contact sensor, an electrical sensor (especially a resistance sensor), a magnetic sensor, and an optical sensor, etc. However, the upper liquid level detection device and / or the lower liquid level detection device are not limited to the above-mentioned sensors / switches.

[0029] The liquid sensor may be any type of sensor that detects the presence of liquid. For example, the liquid sensor may include, but is not limited to, a capacitor whose capacitance changes when liquid is present, such as when liquid enters a gap between electrodes of the capacitor. The contact sensor may include one or more electrodes integrated into or laid flat on the inner wall of the flow channel, wherein the electrodes may measure electrical parameters such as capacitance, resistance, or inductance. The optical sensor may include a camera configured to generate image data and a programmable processor configured to process the image data.

[0030] The optical sensor may include a camera that takes one or more pictures through a transparent wall or window of the flow channel, and an electronic device configured to determine whether the liquid level is visible based on the one or more pictures taken by the camera. To this end, the optical sensor may also include an optical waveguide and / or may be configured to detect a change in color or brightness at a transparent portion of the wall of the flow channel when the liquid level is visible. In this case, the term "liquid level" may not only refer to the position of the surface of the liquid. Additionally or alternatively, the term "liquid level" may also refer to a detectable separation line between the liquid and the air or any other fluid or material located above the liquid level.

[0031] Alternatively, the optical sensor may include a light source, such as a laser, LED or bulb, and a light detector, wherein the power or intensity detected by the light detector changes as the liquid level in the flow channel reaches a predetermined upper liquid level and / or a predetermined lower liquid level, respectively. However, it will be appreciated that the upper and / or lower liquid level detection device is not limited to the above-described embodiments.

[0032] The currently proposed device for measuring the flow rate of a liquid may also include a component that is at least partially arranged in the flow channel and is configured to change the volume of the flow channel, for example between the valve and the upper predetermined liquid level, or between the lower predetermined liquid level and the upper predetermined liquid level. For example, if the flow rate to be measured is low, the measurement process can be accelerated by reducing the volume of the flow channel between the valve and the upper predetermined liquid level. Similarly, if the flow rate to be measured is high, the measurement speed can be reduced by increasing the volume of the flow channel between the valve and the upper predetermined liquid level. For example, the component for changing the volume of the flow channel may include a piston and / or an inflatable balloon that can be at least partially moved into the flow channel and the balloon can be at least partially inflated in the flow channel.

[0033] The flow channel may have a first end and a second end below the first end. An inlet port of the flow channel may be disposed at the first end of the flow channel. An outlet port of the flow channel may be disposed at the second end of the flow channel. The valve is then typically configured to close the flow channel at or above the outlet port.

[0034] The flow channel may include an upper section including an upper predetermined liquid level and an intermediate section extending between the valve and the upper section. The maximum cross-sectional area of ​​the upper section may be smaller than the minimum cross-sectional area of ​​the intermediate section, for example, 2 times or more smaller, or 4 times or more smaller. For example, the volume of the intermediate section of the flow channel may account for at least 50%, at least 70%, or at least 90% of the volume of the portion of the flow channel extending from the valve to the upper predetermined liquid level. The upper section of the flow channel may have a constant cross-sectional area, or may include a section with a constant cross-sectional area. Similarly, the intermediate section of the flow channel may have a constant cross-sectional area, or may include a section with a constant cross-sectional area.

[0035] Determining whether the liquid level in the flow channel has reached the upper predetermined liquid level in the narrower upper section of the flow channel improves the measurement accuracy of the volume ΔV through which the liquid in the flow channel rises to the upper predetermined liquid level because in the narrower upper section, the liquid level rises faster as ΔV increases.

[0036] The flow channel may include a lower section, the lower section including the lower predetermined liquid level and extending between the valve and the middle section. The maximum cross-sectional area of ​​the lower section may be smaller than the minimum cross-sectional area of ​​the middle section, for example 2 or more times smaller, or 4 or more times smaller. The lower section of the flow channel may have a constant cross-sectional area, or may include a section having a constant cross-sectional area.

[0037] Determining whether the liquid level in the flow channel has reached a lower predetermined level in the narrower lower section of the flow channel improves measurement accuracy because inaccurate measurements in the narrower lower section of the flow channel may only change the measured liquid volume by a small amount.

[0038] Since the volume ΔV, which can extend from the lower predetermined level to the upper predetermined level, can be determined in advance with a high level of accuracy, the measurement accuracy of the flow rate q usually depends mainly on the time point t at which the liquid level reaches the upper predetermined level. U The time point t when the liquid level reaches the lower predetermined liquid level L measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The device for measuring flow rate proposed at present will be described in further detail below with reference to the accompanying drawings, in which

[0040] Figure 1 Schematically shows a side view of the device,

[0041] Figure 2 Schematically shows the Figure 1 The cross-sectional view taken along the dotted line II-II in FIG.

[0042] Figure 3 schematically shows a side view of the device in another embodiment, and

[0043] Figure 4 Schematically shows the Figure 3 A cross-sectional view taken along the dotted line VI-VI in FIG. DETAILED DESCRIPTION

[0044] Figure 1 An embodiment of a device 100 for measuring a flow rate of a liquid according to a first embodiment is shown. The device 100 comprises a tube 1 forming a flow channel 1a. Here, the tube 1 has a substantially straight and elongated shape. The flow channel 1a has a first end 3 and a second end 4. Figure 1 , the tube 1 and flow channel 1a are oriented to extend vertically from an inlet port 2 at a first end 3 to an outlet port 6 at a second end 4. Liquid fed to the flow channel 1a via the inlet port 2 can flow through the flow channel 1a in the direction indicated by arrow 5 under the influence of gravity or only under the influence of gravity. The device 100 also includes a valve 7. The valve 7 can selectively open and close the flow channel 1a. In Figure 1 In the embodiment depicted in , valve 7 is disposed at the second end 4 of the flow channel. The device 100 may further include a valve driver 8 for operating the valve 7. Once the valve 7 closes the flow channel 1a, the level of the liquid fed to the flow channel 1a above the valve 7 via the inlet port 2 rises above the valve 7.

[0045] The flow channel 1a comprises Figure 1 , and the like. The upper section of the flow channel 1a extends from A to B. Here, the upper section AB has a constant cross-sectional area. The middle section of the flow channel 1a extends from B to E. Here, the middle section BE includes a section extending from C to D, which has a constant cross-sectional area. In the embodiment described here, the other sections of the middle section BE extend from B to C and from D to E, respectively, and each has a conical shape. The middle section BE extends between the valve 7 and the upper section AB. The lower section of the flow channel 1a extends from E to F. Here, the lower section EF has a constant cross-sectional area. The lower section EF extends between the valve 7 and the middle section BE. The cross-sectional area of ​​the upper section AB is smaller than the maximum cross-sectional area of ​​the middle section BE extending from C to D, for example, 9 times or more. Similarly, the cross-sectional area of ​​the lower section BE is smaller than the maximum cross-sectional area of ​​the middle section BE, for example, 9 times or more.

[0046] The device 100 further comprises a measuring unit 20. The measuring unit 20 comprises an upper liquid level detection device 10, a lower liquid level detection device 11 and a control unit 9 connected to the detection devices 10 and 11. Figure 1 In the embodiment depicted in FIG. 2 , the detection devices 10 and 11 are arranged outside the flow channel 1 a .

[0047] The upper liquid level detection device 10 is configured to determine whether the liquid level in the flow passage 1a has reached Figure 1 The upper predetermined level 10a is indicated by a dashed line in FIG. The upper predetermined level 10a can be determined, for example, by the position of the upper level detection device 10 along the flow channel 1a. Here, the upper level detection device 10 and the upper predetermined level 10a are located in the upper section AB of the flow channel 1a.

[0048] Similarly, the lower liquid level detection device 11 is configured to determine whether the liquid level in the flow channel 1a has reached the value after the valve 7 has been closed. Figure 1 The lower predetermined level 11a is indicated by a dashed line in FIG. The lower predetermined level 11a can be determined, for example, by the position of the lower level detection device 11 along the flow channel 1a. Here, the lower level detection device 11 and the lower predetermined level 11a are located in the lower section EF of the flow channel 1a.

[0049] Alternatively, the lower predetermined level 11a may be determined by the position of the valve 7 along the flow channel. In this case, the device 100 typically does not comprise the lower level detection device 11.

[0050] The volume ΔV of the portion through which the liquid level of flow channel 1a rises to the upper predetermined level after valve 7 has closed flow channel 1a is typically given by the volume of the portion of flow channel 1a extending from lower predetermined level 11a to upper predetermined level 10a.

[0051] exist Figure 1 In the embodiment of the device 100 depicted in FIG. 1 , one or both of the liquid level detection devices 10, 11 may include an optical device such as a camera. For example, these cameras may be configured to capture images of the optically transparent windows 12 and 13 of the tube 1. For example, the windows 12, 13 may include glass windows that may be integrated into the wall of the tube 1. For example, the inner wall of the tube 1 including the glass windows 12, 13 may be flat so as not to disturb the flow of the liquid through the flow channel 1a.

[0052] For example, the two cameras of the liquid level detection devices 10 and 11 may be configured to send image data to the control unit 9. The control unit 9 may include a processing unit 9a. The processing unit 9a may be configured to process the image data received from the detection devices 10 and 11, and obtain whether the liquid level in the flow channel 1a has reached one or both of the detection windows 12 and 13 associated with the cameras of the detection devices 10 and 11, respectively.

[0053] The control unit 9 may further include a timer 9b in communication with the processing unit 9a. The timer 9b may be configured to determine and / or record a time point t at which the liquid level in the flow channel 1a has reached the lower predetermined liquid level 11a. L And the timer 9b may be configured to determine and / or record the time point t at which the liquid level in the flow channel 1a has reached the upper predetermined liquid level 10a. U The processing unit 9a may then be configured to measure or determine the time Δt=t t taken for the liquid in the flow channel 1a to rise from the lower predetermined level 11a to the upper predetermined level 10a. U -t L And based on Δt and the known volume ΔV, the processing unit 9a can then determine the flow rate q of the liquid fed to the flow channel 1a above the valve 7, for example according to q=ΔV / Δt=ΔV / (t U -t L ). The indicator unit 9c can then display, for example, the numerical value of the flow rate q.

[0054] The timer 9b may also be in communication with the valve actuator 8. For example, in an alternative embodiment of the device 100 not explicitly depicted here, in which the lower predetermined level 11a is defined by the position of the valve 7, the timer 9b may be configured to determine the point in time at which the valve 7 closes the flow channel 1a. In this case, t L It can be given by the point in time when the valve 7 closes the flow channel 1 a and the liquid fed to the flow channel 1 a via the inlet port 2 starts to rise above the valve 7 .

[0055] Figure 2 The diagram shows the Figure 1 A cross section of the flow channel 1a is taken along the dashed line II-II. Here and in the following, repeated features in the different figures are denoted by the same reference numerals. Figure 2 , in section CD of flow channel 1 a , the tube 1 has a circular cross section.

[0056] Figure 3 An embodiment of a device 200 for measuring a liquid flow rate according to a second embodiment is shown. Figure 3 The device 200 is Figure 1 For the sake of brevity, only the following description will be given in detail. Figure 3 The device 200 and Figure 1 Unless otherwise expressly stated, Figure 3 The device 200 may include Figure 1 The same features as device 100.

[0057] Figure 4 Shown along Figure 3 The dotted line IV-IV shown in the figure intercepts Figure 3 The cross section of the tube 1 of the device 200. Figure 1 The device 100 is different, Figure 3 The tube 1 of the device 200 has a polygonal cross section, more specifically a rectangular cross section.

[0058] and Figure 1 The device 100 is also different in that Figure 3 In the device 200, the upper liquid level detection device 10 includes at least one electrode that can be electrically insulated from the material of the tube 1. For example, the tube 1 of the device 200 can be made of metal. Figure 3 The upper level detection device 10 of the device 200 may be a device for measuring, for example, resistance, capacitance or inductance. The lower level detection device 11 of the device 200 may be identical to the first device 10 of the device 200 and operate according to the same principle.

[0059] And with Figure 1 The device 100 is also different in that Figure 3 The device 200 comprises a piston 15 and a piston driver 16. The piston 15 is at least partially disposed in the flow channel 1a, more specifically in a section CD of the middle section BE of the flow channel 1a. The piston driver 16 is configured to selectively reduce the volume of the middle section BE of the flow channel 1a by advancing the piston further into the flow channel 1a, or to increase the volume of the middle section BE of the flow channel 1a by withdrawing or at least partially withdrawing the piston from the flow channel 1a.

Claims

1. A device (100; 200) for measuring a liquid flow rate, comprising: Flow channel (1a); a valve (7) for selectively opening and closing the flow channel (1a); as well as A measuring unit (20), characterized in that the measuring unit is configured to determine the time Δt taken for the liquid fed to the flow channel (1a) above the valve (7) to rise to an upper predetermined liquid level (10a) in the flow channel (1a) after the valve (7) has closed the flow channel (1a).

2. The device (100; 200) according to claim 1, characterized in that The measuring unit (20) is configured to determine the flow rate q of the liquid fed to the flow channel (1a) above the valve (7) according to q=ΔV / Δt, wherein ΔV is the known volume of the portion of the flow channel (1a) through which the liquid rises to the upper predetermined liquid level (10a).

3. The device (100; 200) according to claim 1, characterized in that The measuring unit (20) comprises an upper liquid level detection device (10) configured to determine whether the liquid level in the flow channel (1a) has reached the upper predetermined liquid level (10a).

4. The device (100; 200) according to claim 3, characterized in that The measuring unit (20) is configured to measure the liquid level at a predetermined upper liquid level (10a) based on a time point t U to determine the Δt.

5. The device (100; 200) according to claim 3, characterized in that The measuring unit (20) comprises a lower liquid level detection device (11) configured to determine whether the liquid level in the flow channel (1a) has reached a lower predetermined liquid level (11a) provided between the valve (7) and the upper predetermined liquid level (10a).

6. The device according to claim 5, characterized in that Also included is a component that is at least partially disposed in the flow channel (1a) and is configured to change the volume of the flow channel (1a) between the valve (7) and the upper predetermined liquid level (10a) or between the lower predetermined liquid level (11a) and the upper predetermined liquid level (10a).

7. The device (100; 200) according to claim 6, characterized in that The assembly comprises a movable piston (15) and / or an inflatable ball.

8. The device (100; 200) according to claim 5, characterized in that The upper liquid level detection device (10) and / or the lower liquid level detection device (11) comprises a liquid sensor.

9. The device (100; 200) according to claim 5, characterized in that The upper liquid level detection device (10) and / or the lower liquid level detection device (11) comprises a contact sensor.

10. The device (100; 200) according to claim 5, characterized in that The upper liquid level detection device (10) and / or the lower liquid level detection device (11) comprises an optical sensor.

11. The device (100; 200) according to claim 5, characterized in that The upper liquid level detection device (10) and / or the lower liquid level detection device (11) comprises an electric sensor.

12. The device (100; 200) according to claim 11, characterized in that The electrical sensor is a resistive sensor.

13. The device (100; 200) according to claim 5, characterized in that The measuring unit (20) is configured to further determine the time point t at which the liquid level reaches the lower predetermined liquid level (11a). L to determine the Δt.

14. The device (100; 200) according to claim 4 or 13, characterized in that The measuring unit (20) is configured to measure the U -t L Determine Δt.

15. The device (100; 200) according to claim 1, characterized in that The flow channel (1a) has a first end (3) and a second end (4) located below the first end, an inlet port (2) at the first end (3), and an outlet port (6) at the second end (4).

16. The device (100; 200) according to claim 15, characterized in that The valve (7) is configured to close the flow passage (1a) at or above the outlet port (6).

17. The device (100; 200) according to claim 1, characterized in that The flow channel (1a) comprises an upper section (AB) including the upper predetermined liquid level (10a) and a middle section (BE) extending between the valve (7) and the upper section (AB), wherein the maximum cross-sectional area in the upper section (AB) is smaller than the minimum cross-sectional area in the middle section (BE).

18. The device (100; 200) according to claim 17, characterized in that The flow channel (1a) comprises a lower section (EF) including a lower predetermined liquid level (11a) and extending between the valve (7) and the middle section (BE), wherein the maximum cross-sectional area in the lower section (EF) is smaller than the minimum cross-sectional area in the middle section (BE).

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