Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
  • G01F1/007—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring the level variations of storage tanks relative to the time
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
  • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
  • G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid

Definitions

• the invention refers to a method of measurement of the volume of rate of flow of electrical conductive liquids through a vessel according to claim 1.
• the invention also refers to a respective measuring device.
• the measurements of filling heights are conducted wherever the volumes of liquids and the alteration of volume have to be determined.
• the measurements of filling heights are usually done by electrodes, which immerse at ieast partially into the liquid.
• the electrical conductivity or the resistance of the liquid, which is proportional to the filling height or the volume of the liquid, is measured by a suitable measuring device.
• WO 02/27280 A discloses a device using three electrodes one of which is used as reference electrode.
• the electrodes for level measurement are configured in such a way that a measurement value sharply changes when certain limits of the level are exceeded or fallen short of. These leaps of the measurement values can be reliably recognized without high demands on the accuracy of measurement.
• EP 1 484 097 B1 which comprises at least three electrodes, counting means and timers.
• the signals measured by these components are fed to an input of a microprocessor that, on the basis of a resident programme, elaborates important data on the life-span of the cartridge according to the amount of time passed since its first activation and the amount of water treated identified in terms of closure considered important by circuit between the electrodes, and by the ionic concentration of the pollutants, identified in terms of conductivity of the water being treated.
• US 4,724,705 A relates to a fuel measurement device and particularly a device for determining for quantity of a fuel in a fuel tank.
• the fuel level indicator includes a hollow housing, a coded wafer, a short circuit wafer including a wafer substrate, a buoyant member and a continuity bridge.
• the coded wafer is made of a dielectric, ceramic material and extends along the interior length of the hollow housing.
• An electrically conductive wire strand having a known resistance per unit length is wound about the coded wafer to define a "pattern of resistance" representative of the contour of the interior wall of the fuel tank.
• the manufacturing of the fuel level indicator is quite an effort, in particular for manufacturing of the coded wafer.
• DE 10 2005 035 045 A1 discloses a measuring device comprising a measuring element that includes at least one electrode the area of which increases in an exponential manner from one and to the other.
• the benefit of this invention is the fact that the value of electrical conductivity and the absolute value of the liquid level in the vessel need not to be known, if there is an exponential correlation between the measuring values and the volume of the liquid in the vessel.
• the objective of the invention is to provide a method and a measuring device which allows to measure the volume of rate of flow through a vessel in a more precise and easy manner.
• This objective is solved by a method, which is characterized in that the measured values x are measured in time intervals and that the respective filling volumes Vo are determined by comparison of the respective measured values x with calibration measured values x R of at least one reference table comprising at least calibration measured values x R and filling volumes V 0 belonging to them, and that the volume V 0 of the rate of flow is determined from the filling volumes V 0 over a time period, wherein the at least one reference table is constructed by means of calibration measurements using several liquid samples, which have different p-values and different filling heights h in the vessel.
• the time period, in which the filling volumes V 0 are measured can be a predetermined time period.
• the starting time can be the time when f. e. a new filter cartridge is put into the device.
• the time period is limited f. e. by the life time of the cartridge or the time period until the cartridge is replaced.
• the benefit of the invention is that simple electrodes can be used and that the parameter p and the shape of the vessel, which both influence the results of the measurements of the filling height h and therefore of the filling volume V 0 , can be taken into consideration by constructing at least one reference table.
• the calibration measured values x R contained in this reference table are constructed for each shape of the vessel and are deposited in the memory of the electrical conductivity measuring device.
• the mechanical features of the measuring device, in particular the shape and technical details of the electrodes, need not to be adapted to the shape of the vessel when one type of measuring device is used in different vessels. It is only necessary to provide the respective table or tables containing the specific values which reflect the shape and the different types of liquid flowing through the vessel. If the vessels are mass-products only, the construction of at least of one table for each type of vessel is necessary and one and the same measuring device can be used without mechanical adaption.
• the values of the liquid volume in the vessel can be measured in a very precise manner, because not only parameter p but also the shape of the vessel are taken into consideration when the calibration measurements are conducted.
• the at least one reference table can be deposited in a memory of the measuring device.
• One reference table can be sufficient, if for example the influence of parameter p on the measurement of the filling height h is less or not significant and/or there is for example a linear relationship between V 0 and the shape of the vessel. In these cases the correlation between x and h and therefore between x and V 0 can be unique. However, in cases, where the influence of parameter p or where more than one parameter p is getting significant on the result, more than one reference table is needed. The same is true when there is a non-linear correlation between x and V 0 . All these facts result in ambiguous values, if only one table is used. This problem can be overcome by construction of more than one table, for example two or three reference tables in order to get unique and precise results.
• a first reference measured value Xi is measured at least once during said time period.
• This first reference measured value Xi is used to determine at least one of the parameters p of the liquid, which f. e. can be the hardness of water. It is further preferred that the first reference measured value Xi is measured only once at the beginning of a filling procedure starting from an empty vessel. Before the beginning of filling the measuring device is in the status "waiting for water” so that at the first contact of the electrodes with the liquid results in the measurement of the first reference measured value xi. After this measurement the measuring device switches into the status "height measurement” so that all following measured values are classified as measured values x.
• the first reference measured value X 1 is stored and can be used for the calibration of the measured values x until the vessel is empty again and the next filling of the vessel has been started. According to this embodiment it is preferred that said first reference measured value xi is measured by the same two measuring electrodes which are used for the measuring of measured values x.
• this first reference measured value xi is measured every time when the measured value x is measured.
• the measuring device does not distinguish between the very first measurement at the beginning of the filling procedure and the following measurements. This kind of measurement is more precise however it needs a reference electrode.
• the first reference measured value X 1 is measured by this reference electrode and one of the measuring electrodes which are used for the measurements of measured values x.
• this electrode is shielded with the exception of the lower surface.
• a first reference table is constructed which contains the calibration first reference measured values X- I R, which are corresponding to the first reference measured value Xi, and the respective values of parameter p belonging to them, it is also preferred to construct a second reference table which at least contains the calibration measured values x R , the values of parameter p and the respective filling heights h belonging to them and to construct a third reference table which takes into consideration the shape of the vessel and which contains the filling heights h and the respective filling volumes V 0 belonging to them.
• the filling height h at least from the measured value x and the values of the parameter p by comparison with the values of the second reference table.
• the respective filling volume V 0 can be determined from the filling height h by comparison with the values of the third reference table. Starting with the measurement of the measured values x it is a step by step procedure to achieve the filling volume V 0 .
• first calibrated value I 1 which is a function of x and x-i instead of x only. Therefore, in the reference tables 1 and 2 x R is replaced by the corresponding first calibrated value I 1 .
• a second reference measured value X 2 is measured at least once during said time period.
• This second reference measured value X 2 can be measured at the beginning of the filling procedure started from an empty vessel or it can be measured every time when the measured value x is measured.
• This second reference measured value X 2 is preferably measured by means of a reference circuit of the electrical conductivity measuring device.
• This step contributes to the improvement of the precision of the volume measurement.
• I 2 into the first reference table, which contains I 1 , I 2 and the parameter p. From both values I 1 and I 2 the parameter p can be determined in a more precise manner.
• the values of the parameter p can be determined from the values I 1 and I 2 by comparison with values of the first reference table.
• the filling height h can be determined from the values of parameter p and the first calibrated value I 1 by comparison with values of the second reference table.
• the claimed method can be used to measure the volume of the flow rate of various liquids, the measurement of water is preferred.
• the parameter p is the hardness H, which is the most important property of water that affects the electrical conductivity, it's possible to use another property of the ⁇ quid as parameter p, f. e. the pollution of the water.
• the measured values x, X 1 and/or X 2 are a time values.
• the electrical conductivity measuring device comprises an electrical circuit which preferably comprises a capacitor means.
• the charging and/or the discharging time of this capacitor means can be used as measured values x, because it depends from the filling height of the liquid in the vessel.
• the measured values x are measured at least once per second. It is preferred to measure the measured values x at least five times per second. ft is preferred to measure not only the measured value x but also X 1 and X 2 and to calculate I 1 and I 2 . This can be done by an appropriate electronic device which is part of the electrical conductivity measuring device.
• the changes ⁇ V of the filling volumes V 0 are determined and the volume V 0 of the flow rate is determined from the volume changes ⁇ V.
• V 0 of the flow rate It is preferred to determine the volume V 0 of the flow rate from the respective volume increase. This embodiment is preferred if the filling of the vessel happens more rapidly than the draining off of the liquid, f. e. faster by a factor of at least 10. It is assumed that the amount of liquid which is filled in is equivalent to the amount that is drained off.
• the volume V 0 of the flow rate is compared with a volume V max , which is the maximum volume of the liquid, that is characterized by the at least one parameter p and which volume is allowed to flow through the filter device which is arranged downstream of the vessel.
• This filter device contains at least one filter medium. The exhaustion of the filter medium is indicated, when V ma ⁇ is reached.
• the maximum volume V max depends on the at least one parameter p, for example on the hardness H in case of water. Therefore, a fourth reference table is recommended which contains the respective volume Vmax for various values of parameter p. V max can be determined by comparison of the values of the parameter p with the corresponding values deposited in the fourth reference table.
• the exhaustion of the filter medium can be indicated acoustically and/or optically. It is another possibiiity to indicate remaining volumes acoustically and/or optically until the exhaustion of the filter medium is reached.
• a filter cartridge as a filtering device.
• This filter cartridge can be arranged in the outlet of the vessel.
• the objective of the invention is also solved with a measuring device for the determination of the volume V 0 of the flow rate of electrical conductive liquids through a vessel wherein the filling heights h are changing in the vertical direction and wherein the vessel comprises an inlet and an outlet, and a conductivity measuring device which comprises an evaluation unit and at least two measuring electrodes wherein the measuring electrodes are located in the vessel and are connected to the evaluation unit, wherein at least one measured value x is measured by the electrodes characterized in that the evaluation unit is configured for the deposition of at least one reference table comprising at least calibration measured values x R and filling volumes V 0 belonging to them and for comparison of the measured values x of the conductivity measuring device with the calibration measured values x R of the at least one reference table and for the determination of the volume V D of the flow rate from the filling volumes V 0 .
• Both measuring electrodes preferably extend over the total filling height of the vessel wherein these measuring electrodes are not shielded over the total filling height.
• a reference electrode is provided which is arranged near both measuring electrodes.
• This reference electrode is preferably shielded with the exception of its lower surface.
• the electrodes can comprise a constant cross-section along the total length. The benefit of these simple electrodes is the fact that the electrodes can be cut from a long wire in order to adapt the electrodes to the height of the vessel. It is not necessary to manufacture specific electrodes for each type of vessel.
• the evaluation unit preferably comprises a capacitor means. As illustrated in connection with the claimed method the charging and/or discharging time of the capacitor means is the measured value x.
• the evaluation unit preferably comprises a reference circuit having a reference resistor R 0 .
• the measuring device encompasses an indicator unit which can be an optical or an acoustical unit.
• the electrodes can be combined to a measuring stick. It is preferred that the measuring stick is integrated into the wall of the vessel.
• the vessel can be a feeding hopper of a water filtration device.
• a preferred use of the measuring device is the exhaustion measuring device for filter cartridges.
• the indicator unit can preferably indicate the time of change of the filter cartridge.
• Fig. 1 shows a schematic view of a measuring device
• Fig. 2 shows the measuring stick comprising three electrodes
• Fig. 3 shows a vertical cross-section of a jug containing a vessel and measuring device
• Fig. 4 shows the electrical circuit of the measuring device
• Fig. 5 shows a diagram how the measured value x is calculated from the charging and discharging time of the capacitor means
• Fig. 6 shows a vertical cross section of a vessel
• FIG. 1 there is shown a simplified vessel 5 which is filled with water up to the water level 40.
• the vessel comprises a bottom wall 6b and a sidewall 5 having an inlet 7a and an outlet 7b.
• a measuring stick 20 which is approximately 5 mm above the bottom wall 6b of vessel 5.
• the measuring stick comprises two measuring electrodes 22, 24 (first embodiment) and an additional reference electrode 26 (second embodiment) which is located between the measuring electrodes 22 and 24.
• the three electrodes are connected via electrical connections 30, 32, 33 to an evaluation unit 12 which is connected to an indication unit 14. If the water level 40 rises up to water level 40', the volume change is measured by the measuring device.
• a water filtration device 1 which comprises a jug 2 having a grip 3 and a feeding hopper which forms the vessel 5.
• a filter cartridge 50 In the outlet of vessel 5 there is located a filter cartridge 50.
• the measuring device 10 is located inside vessel 5 and the electrodes are connected to the evaluation unit and to the indication unit which are arranged in the lid 4.
• Water to be filtered 8 is filled into vessel 5. After the filtration by the filter cartridge 50 the filtered water 9 flows into and is collected in the jug 2.
• the three electrodes 22, 24 and 26 are connected to an electrical circuit which contains a reference circuit 15 in which a reference resistor 17 is arranged. Furthermore, there is a capacitor means 16 which is charged and discharged by switching the switches 18 and 19.
• fig. 5 the diagram that corresponds to the charging and discharging of the capacitor means 16 is shown.
• the capacitor means is brought to a well defined voltage value by charging and discharging it.
• time T 3 the measuring procedure is started.
• the capacitor means is charged until 1.5 Volts are reached and then it is discharged until the starting value of 0.75 Volts is reached.
• the sum of the charging time T 4 and the discharging time T 5 is used as measured value x.
• a vessel 5 (figure 6) having a bottom wail 6b and a side wall 6a comprises an inlet 7a and an outlet 7b, wherein the outlet is located in the bottom wall 6b.
• the vessel 5 is open at the upper side which forms the inlet 7a.
• the shape of the vessel is defined by side wall 6a which are inclined upwards like a cone. At the left hand sight of vessel 5 there is indicated the height h in mm and the corresponding filling volume V 0 . There is a non-finear correlation between height h and volume V because the volume increases in a non-linear manner when the water level rises.
• both measuring electrodes 22, 24 are used to measure the hardness value.
• the rising water level contacts the lower tips of both electrodes so that a first measurement can be done. Since the measuring device is in the status "waiting for water" the first measurement is the measurement of the first reference measured value Xi. After this measurement all further measurements concern the measurement of the measured values x.
• the second embodiment two measuring electrodes and a reference electrode
• only one measuring electrode 22 or 24 and the reference electrode 26 are used to measure the hardness value.
• One first measurement concerns the measurement of x between electrodes 22, 24 and another first measurement concerns the measurement of X 1 between f. e. electrode 22 and the reference electrode 26.
• the hardness value H is determined by comparison Xi with the values of table 1.
• the measured value x might be falsified by various parameters. Therefore it is recommended to normalize the measured value x by the reference measurement of the reference electrode 26.
• the first calibrated value U Xi/x is for example 15.
• the electronic components of the evaluation unit 12 might also falsify the measured values. Therefore, it is recommended the first reference measured value Xi by a measurement of the reference resistor Ro located in the reference circuit 15 in order to determine the second reference measured value X 2 .
• table 2 contains the measured values x instead of I 1 .
• a fourth table (table 4, figure 11 ) is used.
• the volume values It is preferred to determine the volume values and to compare them with the Vmax value every time when the value x is measured.
• the value x is preferably measured five times a second, so that a high precision can be achieved.

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
• Water Treatment By Sorption (AREA)
• Measuring Volume Flow (AREA)

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• 2009
  • 2009-03-27 US US12/736,263 patent/US8171802B2/en not_active Expired - Fee Related
  • 2009-03-27 MX MX2010007963A patent/MX2010007963A/es not_active Application Discontinuation
  • 2009-03-27 CA CA2712055A patent/CA2712055A1/en not_active Abandoned
  • 2009-03-27 JP JP2011501239A patent/JP5559141B2/ja not_active Expired - Fee Related
  • 2009-03-27 TW TW098110081A patent/TW200946881A/zh unknown
  • 2009-03-27 EP EP09725047A patent/EP2265905B1/en not_active Not-in-force
  • 2009-03-27 WO PCT/EP2009/053644 patent/WO2009118402A1/en not_active Ceased
  • 2009-03-27 CN CN2009801110504A patent/CN101981415B/zh not_active Expired - Fee Related
  • 2009-03-27 PL PL09725047T patent/PL2265905T3/pl unknown
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  • 2009-03-27 BR BRPI0910117A patent/BRPI0910117A2/pt not_active Application Discontinuation
  • 2009-03-27 RU RU2010144054/28A patent/RU2488779C2/ru active

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