EP1403522B1 - Method for detecting a differential pressure - Google Patents

Method for detecting a differential pressure Download PDF

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Publication number
EP1403522B1
EP1403522B1 EP02021526A EP02021526A EP1403522B1 EP 1403522 B1 EP1403522 B1 EP 1403522B1 EP 02021526 A EP02021526 A EP 02021526A EP 02021526 A EP02021526 A EP 02021526A EP 1403522 B1 EP1403522 B1 EP 1403522B1
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EP
European Patent Office
Prior art keywords
pressure
level
fluid
pump
pressure sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP02021526A
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German (de)
French (fr)
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EP1403522A1 (en
Inventor
Peter Jungklas Nybo
Lasse Iives
Heikki Yli-Korpela
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Grundfos AS
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Grundfos AS
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Filing date
Publication date
Application filed by Grundfos AS filed Critical Grundfos AS
Priority to DE50205041T priority Critical patent/DE50205041D1/en
Priority to EP02021526A priority patent/EP1403522B1/en
Priority to US10/670,953 priority patent/US6981399B1/en
Priority to CN03159838.2A priority patent/CN1262821C/en
Publication of EP1403522A1 publication Critical patent/EP1403522A1/en
Application granted granted Critical
Publication of EP1403522B1 publication Critical patent/EP1403522B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D15/00Control, e.g. regulation, of pumps, pumping installations or systems
    • F04D15/02Stopping of pumps, or operating valves, on occurrence of unwanted conditions
    • F04D15/0209Stopping of pumps, or operating valves, on occurrence of unwanted conditions responsive to a condition of the working fluid
    • F04D15/0218Stopping of pumps, or operating valves, on occurrence of unwanted conditions responsive to a condition of the working fluid the condition being a liquid level or a lack of liquid supply

Definitions

  • the invention relates to a method for detecting a differential pressure or to correct a pressure value detected in a fluid based on a pressure of a surrounding medium and a pump system with a level sensor and the use of a pressure sensor in a corresponding pump system.
  • Submersible pumps are usually equipped with a level sensor or level switch equipped, which the pump depending on the liquid level in a sump on and off. It can as level sensors pressure sensors are used, which the Detect fluid pressure. As the fluid pressure varies with altitude the liquid level above the pressure sensor changes over the fluid pressure determines the fluid level and the pump be switched on and off accordingly.
  • a level sensor is known for example as a dynamic pressure sensor from DE 1 609 092.
  • the method according to the invention serves to detect a differential pressure or to correct a pressure value detected in a fluid based on a pressure of a surrounding medium, being thereby a pressure difference between a first and a second Pressure, in particular a fluid pressure and a further pressure, for example of the surrounding medium is formed.
  • a first and a second Pressure in particular a fluid pressure and a further pressure, for example of the surrounding medium is formed.
  • the invention becomes a first pressure at one time and at another time recorded a second pressure.
  • the second pressure value corrected on the basis of the first pressure, preferably between two detected pressure values, a pressure difference is determined.
  • This inventive method thus enables a pressure sensor only absolute pressures, but at two different times must capture to determine a pressure difference. It can thus up a differential pressure sensor, which is applied on two sides, omitted become.
  • the method according to the invention enables the determination a pressure difference with a one-sided acted upon sensor.
  • This has the further advantage that in such a sensor, which usually has a membrane, the detection electronics the side of the membrane can be arranged, which is not with Pressure is applied. This simplifies the insulation or sealing the electronics to the fluid in which determines the pressure shall be. It is thus possible a simplified sensor structure.
  • At least one serving as a level sensor in a pump Pressure sensor is provided and at the one time the Ambient pressure and at the other time the pressure of the the fluid to be pumped detected.
  • This embodiment of the method allows the construction of a simplified level sensor for a pump. It is no longer necessary to apply a double-sided Pressure sensor to use, which at the same time from the ambient pressure and is acted upon by the pressure of the fluid to be delivered, and about the measured differential pressure to the height of the fluid level determine.
  • a pressure sensor acted upon on one side be used, the ambient pressure and the pressure of the fluid to be delivered by the pump at two different times be determined. This method can preferably be used there be where pressure changes in the environment comparatively run slowly.
  • the atmospheric Ambient pressure changes relatively slowly while The pressure of the fluid to be pumped due to rapid changes of the fluid level can change quickly. Because of the slow Changes in the ambient pressure is a constant detection of the Ambient pressure to correct the fluid pressure is not required. It is sufficient to the ambient pressure at predetermined times capture and then the currently determined fluid pressure with this to correct the previously recorded value.
  • the detection of the ambient pressure and the pressure of the fluid to be delivered may preferably done by one and the same sensor.
  • the sensor can over Piping with the fluid and the surrounding medium or the Environment in turn to take turns or successively the pressures of the fluid and the surrounding medium or the To determine the environment.
  • the pressure sensor is used to detect the ambient pressure to the one Time in a position above the surface of the promoted Brought fluids. This can be done by moving the pressure sensor or Change the fluid level done. If the sensor is above the Fluid levels is located, he is outside of the fluid in the Environment and can determine the ambient pressure there.
  • the pressure sensor for detecting the pressure of the promoting fluid at the other time in a position below the surface of the fluid to be delivered. In this position is the pressure sensor is immersed in the fluid and can increase the fluid pressure determine.
  • the fluid level is preferred lowered below the level of the pressure sensor, and the pressure sensor detects the ambient pressure to correct the detected in the fluid Pressure value.
  • the lowering of the fluid level below the level of Pressure sensor is preferably carried out by the pump itself. This will be the pump by a control device so driven that it to a predetermined time at which determines the ambient pressure should be, the fluid pumped far enough that the pressure sensor pumps out and outside of the fluid, the pressure of the surrounding medium or can determine the ambient pressure.
  • This method allows only one pressure sensor to determine the pressure of the surrounding Medium and the fluid pressure without consuming and long connection lines are required which the pressure sensor with the surrounding medium and to be conveyed Connect fluid. Rather, the pressure sensor for determining the Ambient pressure temporarily exposed by pumping off the fluid.
  • the fluid level is preferably to a predetermined value below the level of the Pressure sensor lowered. This will ensure that the Pressure sensor is actually located outside of the fluid and the Can determine the pressure of the surrounding medium correctly. That this Level of the pressure sensor has been reached or undershot, can thereby be found that when lowering the fluid level of the Pressure detected by the pressure sensor initially drops and upon reaching the Levels of the pressure sensor then remains constant.
  • the fluid level after reaching the level the pressure sensor further lowered during a predetermined period of time.
  • a pump can be controlled so that they still reach for a predetermined after reaching the level of the pressure sensor Duration continues to ensure that the Pressure sensor for determining the pressure of the surrounding medium is exposed.
  • the time span in which the fluid level is lowered further becomes preferably based on the previously detected by the level sensor Decreasing speed of the fluid level calculated. In this way can be ensured regardless of the size of the pump sump be that the pressure sensor is exposed so that when determining the pressure of the surrounding medium of the pressure sensor a predetermined amount is located above the fluid surface.
  • One such predetermined distance between pressure sensor and fluid surface can thus be maintained without the actual fluid level after falling below the level of the pressure sensor even further must be determined.
  • the pump becomes after reaching the level of the pressure sensor after expiration of the predetermined period of time or upon reaching a predetermined fluid level below the level of the pressure sensor off. This ensures that even during the Determining the pressure of the surrounding medium a sump not completely drained and in particular the pump is not Run dry, making it difficult to prevent a later restart could. It ensures that the suction mouth of a pump always located below the fluid level.
  • the detection of the ambient pressure takes place only when the fluid level is below a predetermined time the level of the pressure sensor remains. This can be determined be that after switching off the pump, the fluid level is not rises too fast and at a not too high speed again. If the fluid level rises too fast, it could be the case that the flow of the fluid by pumping out another feed corresponds to the pump sump, so that in fact the fluid level even does not fall off and the sensor is not pumped accordingly.
  • a method step for determining the ambient pressure is preferred started when the fluid level with a predetermined Minimum speed begins to decline.
  • the determination of the ambient pressure can thus be started preferably in the way that first the pump is started to lower the fluid level. Now if the pressure sensor detects that the measured pressure or the fluid level at a predetermined minimum speed decreases, a control device passes the process described above to determine the ambient pressure. Since this process only is started at a predetermined minimum descent rate, can be ensured that not a drop in ambient pressure just to start the process to determine the ambient pressure leads.
  • the detection of the pressure of the surrounding medium takes place at predetermined, preferably regular times.
  • the ambient pressure can be determined hourly, with following the determined fluid pressure values with the determined Value of the ambient pressure to be corrected.
  • the intervals, in which the ambient pressure is determined depend on, with what speed to expect changes in ambient pressure are. If faster changes in the pressure of the surrounding Medium is to be expected, is a more frequent determination of this Pressure required to ensure a sufficiently accurate correction of the Fluid to ensure certain pressure value. Are only very slow To expect pressure changes in the surrounding medium The intervals between the individual pressure measurements in the be chosen longer surrounding medium.
  • the invention further relates to a pump system with a level sensor, which has a pressure sensor for determining an absolute pressure.
  • a level sensor which has a pressure sensor for determining an absolute pressure.
  • the pump system has a control device on which the pump depends on the measured values of the level sensor on and / or off.
  • the inventive Pump a calibration device on which the pump so controls that for calibration, a fluid level below the level of Pressure sensor is lowered, so that this the pressure of a surrounding Medium, z. B. detects the air pressure.
  • Such a calibration process preferably takes place during operation to predetermined Times, more preferably at regular intervals, around the detected by the pressure sensor in the fluid to be delivered To correct pressure values based on the ambient pressure, so that based on the pressure difference between fluid pressure and ambient pressure the height of the fluid level above the pressure sensor in ongoing operation can be determined to suit the pump accordingly on and / or off.
  • the pump according to the invention thus requires no differential pressure sensor and no line in the Environment to constantly have a differential pressure between environment and Determine fluid. Since the determination of fluid pressure and ambient pressure not at the same time, but with a time delay it is possible to use one and the same pressure sensor to determine the ambient pressure and the pressure of the fluid to be delivered. To determine the ambient pressure, only the pressure sensor, which is in the fluid during normal operation, as described above, pumped free.
  • the level sensor, the control device and the calibration device Part of a pump unit.
  • the way is an easy to use or to be assembled pump unit created since all control and measuring equipment in the pump unit are integrated.
  • all facilities integrated into the pump housing so that the pump unit merely inserted or suspended in a pump sump must become.
  • the pressure sensor is preferably above the suction mouth of the pump arranged. In this way, the pump is prevented from getting in the way the free pumping of the pressure sensor runs dry, resulting in a later restart complicate or prevent. It can be guaranteed that even during the determination of the ambient pressure, when the fluid level is lowered below the level of the pressure sensor is, the suction mouth is constantly located in the fluid.
  • the pressure sensor is preferably mounted on the stator or pump housing. This simplifies assembly, as the pressure sensor is not separate from the pump at a predetermined position in the sump must be attached. The sensor is always at one predetermined position relative to the suction port of the pump. If the Pressure sensor firmly connected to the stator or pump housing or attached to it, it is for use of the pump only necessary to insert these into the pump sump.
  • control device comprising the calibration device in a terminal box or in the pump or stator housing arranged.
  • the pressure sensor is preferably an unidirectional absolute pressure sensor. This allows a simple and inexpensive design of the pressure sensor. For example, a membrane in the Pressure sensor from one side to be pressurized while the required electronics for determining the diaphragm deflection the opposite side of the membrane protected from the fluid can be arranged.
  • the invention further relates to the use of a unilaterally acted upon Pressure sensor in a pump system according to the preceding Description, where the pressure sensor only via electrical connection cables features.
  • a tubing to the surface above the fluid level to guide the differential pressure sensor from one side with to apply the ambient pressure. According to the invention Method and the pump system according to the invention is this no longer necessary, but can act on one side Pressure sensor used in the pump system according to the invention become.
  • the inventive method and in particular the inventive Pump system can be used wherever, too Measuring or control purposes, a differential pressure between a fluid and a surrounding medium must be determined. It is preferred the method used in a pump, in which over a Pressure sensor, the fluid level is detected to the pump on and / or off. To determine the exact fluid level is It requires the differential pressure between a pressure in a given Height in the fluid and to determine the ambient pressure otherwise fluctuations in the ambient pressure will be the value determined for the fluid level. According to the According to the invention, the ambient pressure and the pressure in the fluid is not simultaneous but different Times determined in succession.
  • a submersible pump as for example for groundwater lowering or used in sewage wells, becomes too pre-determined Time points lowered by the pump the fluid level so far in that the pressure sensor serving as a level sensor pumps out is, d. H. located above the fluid level. In this condition the pressure sensor can measure the ambient pressure, i. H. the air pressure determine. Then the pump sump runs full again and the Pressure sensor is again below the fluid level, so that he hydrostatic pressure detected, which by the standing above him Fluid is caused.
  • an absolute pressure sensor is used, which one-sided is charged.
  • FIG. 1 the height h of the liquid level in the pump sump or the pressure detected by the pressure sensor over the time t is plotted.
  • the solid line 2 shows the course of the signal emitted by the pressure sensor over time.
  • the pumping process is started so that the liquid level 2 or the pressure signal 2 representing the liquid level drops until the liquid level reaches the value S 2 .
  • the value S 2 corresponds to the height S 2 , in which the pressure sensor is attached to the pump.
  • This Abpumpvorganges detects the control of the pump an average rate of descent, which is shown as a dotted line 4 in the diagram of FIG.
  • the pressure sensor detects the ambient pressure so that the pressure detected by the pressure sensor does not drop any further. Since the control device determines the liquid level in the pump sump via the detected pressure, the liquid level at this time seems to be constant due to the constant pressure for the control device, which is due to the horizontal course of the graph 2 at the height S 2 during the time intervals t 1 and t 2 is shown in Fig. 1.
  • the average sinking rate of the liquid level dh / dt represented by dotted line 4 was determined.
  • the liquid level should be lowered below the level S 2 to the level S 1 .
  • the liquid level, starting from the level S 2 must still be lowered by the height h 1 .
  • the time span t 1 can then be determined in which the pump must continue to run at constant power, so that the liquid level is lowered by the amount h 1 to the level S 1 at a constant sinking speed.
  • t 1 h 1 / (Dh / dt)
  • the pump After the expiration of the time period t 1 , the pump is switched off and the liquid level rises again in the interval t 2 , until it again reaches the level S 2 .
  • the control of the pump again detects a pressure change, and the detected liquid level signal, which is represented by the solid line 2 in FIG. 1, rises again after the interval t 2 has elapsed.
  • the measurement of the ambient pressure is carried out, as long as the interval t 2 is longer than a predetermined interval t 2min . If the sensor signal remains constant at the value S 2 for a shorter period of time than t 2min , there is a case in which the liquid feed into the pump sump compensates for the liquid drain due to the pumping down operation so that the liquid level remains constant. In this condition, the pressure sensor is not pumped, although it detects no further change in pressure. Thus, no measurement of the ambient pressure can be performed at this time.
  • the sensor signal remains constant at the value S 2 in a time interval t 2 > t 2min , it can be assumed that the liquid level has been lowered below the level S 2 of the sensor and the sensor is thus free at this time, ie outside the fluid or the liquid is and can detect the ambient pressure.
  • the Detection of the ambient pressure takes place at predetermined times, for example, every hour. Because changes in ambient pressure much slower or slower than changes in the liquid level, are individual measurements of the ambient pressure in predetermined Time intervals sufficient to those in the liquid or To correct the pressure detected by the fluid to the exact height of the liquid level to be able to determine.
  • the fluid level is proportional to the differential pressure between fluid pressure and ambient pressure.
  • Fig. 2 shows a diagram corresponding to Fig. 1, which illustrates a further state in which no measurement of the ambient pressure is made.
  • the liquid level is first lowered by starting the pump, which is detected by the pressure sensor, which outputs a signal level 2.
  • the signal 2 remains constant in the vicinity of the level S 2 of the sensor. This first causes the control device to assume that the level S 2 has been reached or fallen below, so that the sensor is pumped free. Consequently, it now determines, as explained with reference to FIG. 1, the interval t 1 , in which the pump must continue to lower the liquid level by the predetermined amount h 1 . After expiration of the time period t 1 , the pump is switched off. In the case shown in FIG.
  • the signal 2 then increases again immediately after expiration of the interval t 1 .
  • the signal level 2 thus does not remain constant, as explained with reference to FIG. 1, for a time t 2 > t 2min . From the immediate increase in the signal level 2 can now be concluded that in fact not the liquid level has been lowered below the level S 2 , but that only an inlet into the pump sump has exactly met the pumped by the pump fluid or liquid quantity, so that in the interval t 1, the signal level 2 was constant. Due to the rise in the signal level 2 before the expiration of the time t 2min , the control device now detects an error and does not perform a determination of the ambient pressure, but starts the pump again to start the process described above and to determine the ambient pressure.
  • a second sensor in shape a pressure sensor or other level or humidity sensor be provided, which detects whether the used for pressure measurement Pressure sensor located above or below the liquid level is. This is important to using one and the same sensor ambient pressure and the pressure in the fluid at different times to be able to determine and the pressure measured in the fluid Correct the basis of the ambient pressure or the differential pressure to be able to determine.
  • a pressure sensor for determination the ambient pressure after lowering the fluid level arranged and in the region of the lower end of the submersible pump be provided further pressure sensor for determining the fluid pressure.
  • the pressure measurement of ambient pressure causes and fluid pressure at two different times that it is not necessary, the pressure sensor to determine the ambient pressure constantly above the fluid level to keep what extra would require connecting lines.
  • Another exemplary application of the invention Method is a differential pressure measurement in a closed Heating circuit to that generated by a circulating pump To determine pressure.
  • a differential pressure sensor which constantly the Differential pressure between suction and discharge side of the pump detected, omitted become. It is only an absolute pressure sensor required, which the two to be compared or subtracted from each other Pressures determined at two different times, where first the first or first of the second pressure value are determined can.

Description

Die Erfindung betrifft ein Verfahren zur Erfassung eines Differenzdruckes oder zur Korrektur eines in einem Fluid erfassten Druckwertes auf Grundlage eines Druckes eines umgebenden Mediums sowie ein Pumpensystem mit einem Niveausensor und die Verwendung eines Drucksensors in einem entsprechenden Pumpensystem.The invention relates to a method for detecting a differential pressure or to correct a pressure value detected in a fluid based on a pressure of a surrounding medium and a pump system with a level sensor and the use of a pressure sensor in a corresponding pump system.

Tauchpumpen sind üblicherweise mit einem Niveausensor bzw. Niveauschalter ausgerüstet, welcher die Pumpe in Abhängigkeit des Flüssigkeitsstandes in einem Pumpensumpf ein- und ausschaltet. Dabei können als Niveausensoren Drucksensoren eingesetzt werden, welche den Fluiddruck erfassen. Da sich der Fluiddruck in Abhängigkeit der Höhe des Flüssigkeitsspiegels oberhalb des Drucksensors ändert, kann über den Fluiddruck das Flüssigkeitsniveau bestimmt werden und die Pumpe entsprechend ein- und ausgeschaltet werden. Ein solcher Niveausensor ist beispielsweise als Staudrucksensor aus DE 1 609 092 bekannt.Submersible pumps are usually equipped with a level sensor or level switch equipped, which the pump depending on the liquid level in a sump on and off. It can as level sensors pressure sensors are used, which the Detect fluid pressure. As the fluid pressure varies with altitude the liquid level above the pressure sensor changes over the fluid pressure determines the fluid level and the pump be switched on and off accordingly. Such a level sensor is known for example as a dynamic pressure sensor from DE 1 609 092.

Problematisch ist dabei, dass sich ebenfalls Änderungen des atmosphärischen Druckes auf die Erfassung des Drucksensors auswirken. So kommt es zu Ungenauigkeiten bei der Bestimmung des Flüssigkeitsniveaus aufgrund von Schwankungen des Umgebungsdruckes. Um diese zu kompensieren, wurden in der Vergangenheit als Drucksensoren Differenzdrucksensoren eingesetzt, welche die Druckdifferenz zwischen einem Fluiddruck und dem Umgebungsdruck bestimmen und es somit ermöglichen, die genaue Höhe des Flüssigkeitsniveaus oberhalb des Drucksensors zu bestimmen. Der Einsatz dieser Sensoren erfordert jedoch, ein Rohr oder einen Schlauch aus dem Pumpensumpf hinauszuführen, um den Drucksensor auch mit dem Umgebungsdruck beaufschlagen zu können. Dies macht den Aufbau und die Montage derartiger Pumpen recht aufwändig.The problem is that also changes in the atmospheric Pressure on the detection of the pressure sensor impact. So there are inaccuracies in the determination of the liquid level due to fluctuations in ambient pressure. Around In the past, differential pressure sensors were used as pressure sensors to compensate used, which is the pressure difference between a Determine fluid pressure and the ambient pressure and thus it allow the exact height of the liquid level above the To determine pressure sensor. However, the use of these sensors requires to take a pipe or hose out of the sump, to pressurize the pressure sensor with the ambient pressure to be able to. This makes the construction and installation of such Pumps quite expensive.

Es ist daher Aufgabe der Erfindung, ein verbessertes Verfahren zur Korrektur eines in einem Fluid erfassten Druckwertes bei Verwendung eines als Drucksensor ausgebildeten Niveausensors in einer Pumpe sowie ein entsprechendes Pumpensystem zu schaffen, welche einen vereinfachten Aufbau des Pumpensystems ermöglichen.It is therefore an object of the invention to provide an improved method for correction a pressure value detected in a fluid when using a designed as a pressure sensor level sensor in a pump and a to provide appropriate pumping system, which is a simplified Allow the construction of the pump system.

Diese Aufgabe wird durch ein Verfahren mit den im Anspruch 1 angegebenen Merkmalen, durch ein Pumpensystem mit den im Anspruch 11 angegebenen Merkmalen sowie durch die Verwendung eines Drucksensors mit den im Anspruch 17 angegebenen Merkmalen gelöst. Bevorzugte Ausführungsformen ergeben sich aus den zugehörigen Unteransprüchen.This object is achieved by a method with the specified in claim 1 Characteristics, by a pump system with the in claim 11 specified characteristics and by the use of a pressure sensor solved with the features specified in claim 17. preferred Embodiments emerge from the associated subclaims.

Das erfindungsgemäße Verfahren dient zur Erfassung eines Differenzdruckes oder zur Korrektur eines in einem Fluid erfassten Druckwertes auf Grundlage eines Druckes eines umgebenden Mediums, wobei dabei eine Druckdifferenz zwischen einem ersten und einem zweiten Druck, insbesondere einem Fluiddruck und einem weiteren Druck, beispielsweise des umgebenden Mediums gebildet wird. Erfindungsgemäß wird zu einem Zeitpunkt ein erster Druck und zu einem anderen Zeitpunkt ein zweiter Druck erfasst. Anschließend wird der zweite Druckwert auf Grundlage des ersten Druckes korrigiert, wobei bevorzugt zwischen beiden erfassten Druckwerten eine Druckdifferenz bestimmt wird. Dieses erfindungsgemäße Verfahren ermöglicht somit, dass ein Drucksensor lediglich absolute Drücke, allerdings zu zwei verschiedenen Zeitpunkten erfassen muss, um eine Druckdifferenz zu bestimmen. Es kann somit auf einen Differenzdrucksensor, welcher zweiseitig beaufschlagt wird, verzichtet werden. Das erfindungsgemäße Verfahren ermöglicht die Bestimmung einer Druckdifferenz mit einem einseitig beaufschlagten Sensor. Dies hat den weiteren Vorteil, dass in einem solchen Sensor, welcher üblicherweise eine Membran aufweist, die Erfassungselektronik auf der Seite der Membran angeordnet werden kann, welche nicht mit Druck beaufschlagt wird. Dies vereinfacht die Isolation bzw. Abdichtung der Elektronik gegenüber dem Fluid, in dem der Druck bestimmt werden soll. Es wird somit ein vereinfachter Sensoraufbau möglich.The method according to the invention serves to detect a differential pressure or to correct a pressure value detected in a fluid based on a pressure of a surrounding medium, being thereby a pressure difference between a first and a second Pressure, in particular a fluid pressure and a further pressure, for example of the surrounding medium is formed. According to the invention becomes a first pressure at one time and at another time recorded a second pressure. Subsequently, the second pressure value corrected on the basis of the first pressure, preferably between two detected pressure values, a pressure difference is determined. This inventive method thus enables a pressure sensor only absolute pressures, but at two different times must capture to determine a pressure difference. It can thus up a differential pressure sensor, which is applied on two sides, omitted become. The method according to the invention enables the determination a pressure difference with a one-sided acted upon sensor. This has the further advantage that in such a sensor, which usually has a membrane, the detection electronics the side of the membrane can be arranged, which is not with Pressure is applied. This simplifies the insulation or sealing the electronics to the fluid in which determines the pressure shall be. It is thus possible a simplified sensor structure.

Erfindungsgemäß ist zumindest ein als Niveausensor in einer Pumpe dienender Drucksensor vorgesehen und wird zu dem einen Zeitpunkt der Umgebungsdruck und zu dem anderen Zeitpunkt der Druck des von der Pumpe zu fördernden Fluids erfasst. Diese Ausgestaltung des Verfahrens ermöglicht den Aufbau eines vereinfachten Niveausensors für eine Pumpe. Es ist nicht mehr erforderlich, einen zweiseitig beaufschlagten Drucksensor einzusetzen, welcher gleichzeitig vom Umgebungsdruck und von dem Druck des zu fördernden Fluids beaufschlagt wird, und über den gemessenen Differenzdruck die Höhe des Fluidspiegels zu bestimmen. Erfindungsgemäß kann ein einseitig beaufschlagter Drucksensor eingesetzt werden, wobei der Umgebungsdruck und der Druck des von der Pumpe zu fördernden Fluids zu zwei verschiedenen Zeitpunkten bestimmt werden. Dieses Verfahren kann bevorzugt dort eingesetzt werden, wo Druckänderungen in der Umgebung vergleichsweise langsam ablaufen. Bei Pumpen ist dies der Fall, da sich der atmosphärische Umgebungsdruck vergleichsweise langsam ändert, während sich der Druck des zu fördernden Fluids aufgrund schneller Änderungen des Fluidniveaus schnell ändern kann. Aufgrund der langsamen Änderungen des Umgebungsdruckes ist eine ständige Erfassung des Umgebungsdruckes zur Korrektur des Fluiddruckes nicht erforderlich. Es ist ausreichend, den Umgebungsdruck zu vorbestimmten Zeitpunkten zu erfassen und anschließend den laufend bestimmten Fluiddruck mit diesem zuvor erfassten Wert zu korrigieren. Die Erfassung des Umgebungsdruckes und des Druckes des zu fördernden Fluids kann vorzugsweise durch ein und denselben Sensor erfolgen. Dazu kann der Sensor über Rohrleitungen mit dem Fluid und dem umgebenden Medium bzw. der Umgebung in Verbindung stehen, um abwechselnd bzw. nacheinander die Drücke des Fluids und des umgebenden Mediums bzw. der Umgebung zu bestimmen. Dazu können entsprechende Schaltventile in den Rohrleitungen vorgesehen sein, um den Drucksensor abwechselnd mit dem Fluiddruck und dem Druck des umgebenden Mediums zu beaufschlagen.According to the invention, at least one serving as a level sensor in a pump Pressure sensor is provided and at the one time the Ambient pressure and at the other time the pressure of the the fluid to be pumped detected. This embodiment of the method allows the construction of a simplified level sensor for a pump. It is no longer necessary to apply a double-sided Pressure sensor to use, which at the same time from the ambient pressure and is acted upon by the pressure of the fluid to be delivered, and about the measured differential pressure to the height of the fluid level determine. According to the invention, a pressure sensor acted upon on one side be used, the ambient pressure and the pressure of the fluid to be delivered by the pump at two different times be determined. This method can preferably be used there be where pressure changes in the environment comparatively run slowly. For pumps, this is the case, since the atmospheric Ambient pressure changes relatively slowly while The pressure of the fluid to be pumped due to rapid changes of the fluid level can change quickly. Because of the slow Changes in the ambient pressure is a constant detection of the Ambient pressure to correct the fluid pressure is not required. It is sufficient to the ambient pressure at predetermined times capture and then the currently determined fluid pressure with this to correct the previously recorded value. The detection of the ambient pressure and the pressure of the fluid to be delivered may preferably done by one and the same sensor. For this the sensor can over Piping with the fluid and the surrounding medium or the Environment in turn to take turns or successively the pressures of the fluid and the surrounding medium or the To determine the environment. For this purpose, appropriate switching valves in be provided to the piping to the pressure sensor alternately to pressurize with the fluid pressure and the pressure of the surrounding medium.

Der Drucksensor wird zum Erfassen des Umgebungsdruckes zu dem einen Zeitpunkt in eine Position oberhalb der Oberfläche des zu fördernden Fluids gebracht. Dies kann durch Bewegung des Drucksensors oder Veränderung des Fluidniveaus erfolgen. Wenn der Sensor oberhalb des Fluidniveaus angeordnet ist, befindet er sich außerhalb des Fluids in der Umgebung und kann dort den Umgebungsdruck bestimmen.The pressure sensor is used to detect the ambient pressure to the one Time in a position above the surface of the promoted Brought fluids. This can be done by moving the pressure sensor or Change the fluid level done. If the sensor is above the Fluid levels is located, he is outside of the fluid in the Environment and can determine the ambient pressure there.

Entsprechend wird der Drucksensor zum Erfassen des Druckes des zu fördernden Fluids zu dem anderen Zeitpunkt in eine Position unterhalb der Oberfläche des zu fördernden Fluids gebracht. In dieser Position ist der Drucksensor in das Fluid eingetaucht und kann den Fluiddruck bestimmen. Accordingly, the pressure sensor for detecting the pressure of the promoting fluid at the other time in a position below the surface of the fluid to be delivered. In this position is the pressure sensor is immersed in the fluid and can increase the fluid pressure determine.

Bevorzugt wird zur Bestimmung des Umgebungsdruckes das Fluidniveau unter das Niveau des Drucksensors abgesenkt, und der Drucksensor erfasst den Umgebungsdruck zur Korrektur des in dem Fluid erfassten Druckwertes. Die Absenkung des Fluidniveaus unter das Niveau des Drucksensors erfolgt vorzugsweise durch die Pumpe selber. Dazu wird die Pumpe von einer Steuereinrichtung so angesteuert, dass sie zu einem vorgegebenen Zeitpunkt, an dem der Umgebungsdruck bestimmt werden soll, das Fluid soweit abpumpt, dass der Drucksensor freigepumpt wird und außerhalb des Fluids den Druck des umgebenden Mediums bzw. den Umgebungsdruck bestimmen kann. Dieses Verfahren ermöglicht, nur einen Drucksensor zur Bestimmung des Druckes des umgebenden Mediums und des Fluiddruckes einzusetzen, ohne dass aufwändige und lange Verbindungsleitungen erforderlich sind, welche den Drucksensor mit dem umgebenden Medium und dem zu fördernden Fluid verbinden. Vielmehr wird der Drucksensor zur Bestimmung des Umgebungsdruckes vorübergehend durch Abpumpen des Fluids freigelegt.For determining the ambient pressure, the fluid level is preferred lowered below the level of the pressure sensor, and the pressure sensor detects the ambient pressure to correct the detected in the fluid Pressure value. The lowering of the fluid level below the level of Pressure sensor is preferably carried out by the pump itself. This will be the pump by a control device so driven that it to a predetermined time at which determines the ambient pressure should be, the fluid pumped far enough that the pressure sensor pumps out and outside of the fluid, the pressure of the surrounding medium or can determine the ambient pressure. This method allows only one pressure sensor to determine the pressure of the surrounding Medium and the fluid pressure without consuming and long connection lines are required which the pressure sensor with the surrounding medium and to be conveyed Connect fluid. Rather, the pressure sensor for determining the Ambient pressure temporarily exposed by pumping off the fluid.

Nach Erreichen des Niveaus des Drucksensors wird das Fluidniveau vorzugsweise auf einen vorbestimmten Wert unterhalb des Niveaus des Drucksensors abgesenkt. Auf diese Weise wird sichergestellt, dass der Drucksensor sich tatsächlich außerhalb des Fluids befindet und den Druck des umgebenden Mediums fehlerfrei bestimmen kann. Dass das Niveau des Drucksensors erreicht oder unterschritten wurde, kann dadurch festgestellt werden, dass beim Absenken des Fluidniveaus der vom Drucksensor erfasste Druck zunächst abfällt und bei Erreichen des Niveaus des Drucksensors dann konstant bleibt.After reaching the level of the pressure sensor, the fluid level is preferably to a predetermined value below the level of the Pressure sensor lowered. This will ensure that the Pressure sensor is actually located outside of the fluid and the Can determine the pressure of the surrounding medium correctly. That this Level of the pressure sensor has been reached or undershot, can thereby be found that when lowering the fluid level of the Pressure detected by the pressure sensor initially drops and upon reaching the Levels of the pressure sensor then remains constant.

Dazu wird vorzugsweise das Fluidniveau nach Erreichen des Niveaus des Drucksensors während einer vorbestimmten Zeitspanne weiter abgesenkt. So kann eine Pumpe beispielsweise so gesteuert werden, dass sie nach Erreichen des Niveaus des Drucksensors noch für eine vorbestimmte Zeitdauer weiterläuft, so dass sichergestellt wird, dass der Drucksensor zur Bestimmung des Druckes des umgebenden Mediums freigelegt wird.For this purpose, preferably the fluid level after reaching the level the pressure sensor further lowered during a predetermined period of time. For example, a pump can be controlled so that they still reach for a predetermined after reaching the level of the pressure sensor Duration continues to ensure that the Pressure sensor for determining the pressure of the surrounding medium is exposed.

Die Zeitspanne, in welcher das Fluidniveau weiter abgesenkt wird, wird vorzugsweise auf Grundlage der zuvor von dem Niveausensor erfassten Absinkgeschwindigkeit des Fluidniveaus berechnet. Auf diese Weise kann unabhängig von der Größe des Pumpensumpfes sichergestellt werden, dass der Drucksensor derart freigelegt wird, dass bei der Bestimmung des Druckes des umgebenden Mediums der Drucksensor um ein vorbestimmtes Maß oberhalb der Fluidoberfläche gelegen ist. Ein solcher vorbestimmter Abstand zwischen Drucksensor und Fluidoberfläche kann somit eingehalten werden, ohne dass das tatsächliche Fluidniveau nach Unterschreiten des Niveaus des Drucksensors noch weiter bestimmt werden muss.The time span in which the fluid level is lowered further becomes preferably based on the previously detected by the level sensor Decreasing speed of the fluid level calculated. In this way can be ensured regardless of the size of the pump sump be that the pressure sensor is exposed so that when determining the pressure of the surrounding medium of the pressure sensor a predetermined amount is located above the fluid surface. One such predetermined distance between pressure sensor and fluid surface can thus be maintained without the actual fluid level after falling below the level of the pressure sensor even further must be determined.

Vorzugsweise wird die Pumpe nach Erreichen des Niveaus des Drucksensors nach Ablauf der vorbestimmten Zeitspanne oder bei Erreichen eines vorbestimmten Fluidniveaus unterhalb des Niveaus des Drucksensors abgeschaltet. Somit wird sichergestellt, dass auch während der Bestimmung des Druckes des umgebenden Mediums ein Pumpensumpf nicht vollständig leergepumpt wird und insbesondere die Pumpe nicht trockenläuft, was ein späteres Wiederanlaufen erschweren oder verhindern könnte. Es wird gewährleistet, dass der Saugmund einer Pumpe immer unterhalb des Fluidniveaus gelegen ist.Preferably, the pump becomes after reaching the level of the pressure sensor after expiration of the predetermined period of time or upon reaching a predetermined fluid level below the level of the pressure sensor off. This ensures that even during the Determining the pressure of the surrounding medium a sump not completely drained and in particular the pump is not Run dry, making it difficult to prevent a later restart could. It ensures that the suction mouth of a pump always located below the fluid level.

Weiter bevorzugt erfolgt die Erfassung des Umgebungsdruckes nur, wenn das Fluidniveau während einer vorbestimmten Zeitspanne unterhalb des Niveaus des Drucksensors verbleibt. Dies kann dadurch festgestellt werden, dass nach Abschalten der Pumpe das Fluidniveau nicht zu schnell und mit einer nicht zu hohen Geschwindigkeit wieder ansteigt. Steigt das Fluidniveau zu schnell an, könnte der Fall vorliegen, dass der Ablauf des Fluids durch das Abpumpen einem weiteren Zulauf in den Pumpensumpf entspricht, so dass tatsächlich der Fluidspiegel gar nicht abfällt und der Sensor entsprechend nicht freigepumpt wird. Gemäß einer weiteren bevorzugten Ausführungsform wird die Pumpe wieder gestartet, wenn eine Erfassung des Umgebungsdruckes nicht erfolgt. Das bedeutet, wenn festgestellt wird, dass nicht der korrekte Zustand erreicht ist, in welchem der Umgebungsdruck ermittelt werden kann, wird die Pumpe erneut gestartet, um das Fluidniveau weiter abzusenken und den Drucksensor in eine Position oberhalb des Flüssigkeitsniveaus zu bringen, um den Umgebungsdruck zu bestimmen.More preferably, the detection of the ambient pressure takes place only when the fluid level is below a predetermined time the level of the pressure sensor remains. This can be determined be that after switching off the pump, the fluid level is not rises too fast and at a not too high speed again. If the fluid level rises too fast, it could be the case that the flow of the fluid by pumping out another feed corresponds to the pump sump, so that in fact the fluid level even does not fall off and the sensor is not pumped accordingly. According to In another preferred embodiment, the pump restarted when a detection of the ambient pressure is not he follows. That means, if it is determined that not the correct one State is reached, in which the ambient pressure is determined can, the pump is restarted to further lower the fluid level and the pressure sensor to a position above the liquid level to bring to determine the ambient pressure.

Ein Verfahrensschritt zur Ermittlung des Umgebungsdruckes wird vorzugsweise gestartet, wenn das Fluidniveau mit einer vorbestimmten Mindestgeschwindigkeit zu sinken beginnt. Die Bestimmung des Umgebungsdruckes kann somit vorzugsweise auf die Weise gestartet werden, dass zunächst die Pumpe gestartet wird, um das Fluidniveau zu senken. Wenn nun vom Drucksensor festgestellt wird, dass der gemessene Druck bzw. das Fluidniveau mit einer vorbestimmten Mindestgeschwindigkeit sinkt, leitet eine Steuereinrichtung den zuvor beschriebenen Vorgang zur Bestimmung des Umgebungsdruckes ein. Da dieser Vorgang erst bei einer vorbestimmten Mindestsinkgeschwindigkeit gestartet wird, kann sichergestellt werden, dass nicht ein Abfall des Umgebungsdruckes allein zum Start des Vorgangs zur Bestimmung des Umgebungsdruckes führt.A method step for determining the ambient pressure is preferred started when the fluid level with a predetermined Minimum speed begins to decline. The determination of the ambient pressure can thus be started preferably in the way that first the pump is started to lower the fluid level. Now if the pressure sensor detects that the measured pressure or the fluid level at a predetermined minimum speed decreases, a control device passes the process described above to determine the ambient pressure. Since this process only is started at a predetermined minimum descent rate, can be ensured that not a drop in ambient pressure just to start the process to determine the ambient pressure leads.

Vorzugsweise erfolgt die Erfassung des Druckes des umgebenden Mediums zu vorbestimmten, vorzugsweise regelmäßigen Zeitpunkten. Beispielsweise kann der Umgebungsdruck stündlich bestimmt werden, wobei im Anschluss die ermittelten Fluiddruckwerte mit dem ermittelten Wert des Umgebungsdruckes korrigiert werden. Die Zeitabstände, in denen der Umgebungsdruck bestimmt wird, hängen davon ab, mit welcher Geschwindigkeit Änderungen des Umgebungsdruckes zu erwarten sind. Wenn schnellere Änderungen des Druckes des umgebenden Mediums zu erwarten sind, ist eine häufigere Bestimmung dieses Druckes erforderlich, um eine ausreichend genaue Korrektur des in dem Fluid bestimmten Druckwertes zu gewährleisten. Sind lediglich sehr langsame Druckänderungen in dem umgebenden Medium zu erwarten, können die Intervalle zwischen den einzelnen Druckmessungen in dem umgebenden Medium länger gewählt werden.Preferably, the detection of the pressure of the surrounding medium takes place at predetermined, preferably regular times. For example the ambient pressure can be determined hourly, with following the determined fluid pressure values with the determined Value of the ambient pressure to be corrected. The intervals, in which the ambient pressure is determined depend on, with what speed to expect changes in ambient pressure are. If faster changes in the pressure of the surrounding Medium is to be expected, is a more frequent determination of this Pressure required to ensure a sufficiently accurate correction of the Fluid to ensure certain pressure value. Are only very slow To expect pressure changes in the surrounding medium The intervals between the individual pressure measurements in the be chosen longer surrounding medium.

Die Erfindung betrifft ferner ein Pumpensystem mit einem Niveausensor, welcher einen Drucksensor zur Bestimmung eines Absolutdruckes aufweist. Das bedeutet, es kann ein einseitig beaufschlagter Drucksensor eingesetzt werden. Ferner weist das Pumpensystem eine Steuereinrichtung auf, welche die Pumpe in Abhängigkeit der Messwerte des Niveausensors ein- und/oder ausschaltet. Zusätzlich weist die erfindungsgemäße Pumpe eine Kalibrierungseinrichtung auf, welche die Pumpe so steuert, dass zur Kalibrierung ein Fluidniveau unter das Niveau des Drucksensors abgesenkt wird, so dass dieser den Druck eines umgebenden Mediums, z. B. den Luftdruck erfasst. Ein solcher Kalibrierungsvorgang erfolgt vorzugsweise während des laufenden Betriebes zu vorbestimmten Zeitpunkten, weiter bevorzugt in regelmäßigen Abständen, um die von dem Drucksensor in dem zu fördernden Fluid erfassten Druckwerte auf Grundlage des Umgebungsdruckes zu korrigieren, so dass auf Grundlage der Druckdifferenz zwischen Fluiddruck und Umgebungsdruck die Höhe des Fluidstandes oberhalb des Drucksensors im laufenden Betrieb bestimmt werden kann, um die Pumpe entsprechend ein- und/oder auszuschalten. Die erfindungsgemäße Pumpe benötigt somit keinen Differenzdrucksensor und keine Leitung in die Umgebung, um ständig einen Differenzdruck zwischen Umgebung und Fluid zu bestimmen. Da die Bestimmung von Fluiddruck und Umgebungsdruck nicht zum selben Zeitpunkt erfolgt, sondern zeitversetzt, wird es möglich, ein und denselben Drucksensor zur Bestimmung des Umgebungsdruckes und des Druckes des zu fördernden Fluids einzusetzen. Zur Bestimmung des Umgebungsdruckes wird lediglich der Drucksensor, welcher sich im normalen Betrieb im Fluid befindet, wie oben beschrieben, freigepumpt.The invention further relates to a pump system with a level sensor, which has a pressure sensor for determining an absolute pressure. This means it can be a single-acting pressure sensor be used. Furthermore, the pump system has a control device on which the pump depends on the measured values of the level sensor on and / or off. In addition, the inventive Pump a calibration device on which the pump so controls that for calibration, a fluid level below the level of Pressure sensor is lowered, so that this the pressure of a surrounding Medium, z. B. detects the air pressure. Such a calibration process preferably takes place during operation to predetermined Times, more preferably at regular intervals, around the detected by the pressure sensor in the fluid to be delivered To correct pressure values based on the ambient pressure, so that based on the pressure difference between fluid pressure and ambient pressure the height of the fluid level above the pressure sensor in ongoing operation can be determined to suit the pump accordingly on and / or off. The pump according to the invention thus requires no differential pressure sensor and no line in the Environment to constantly have a differential pressure between environment and Determine fluid. Since the determination of fluid pressure and ambient pressure not at the same time, but with a time delay it is possible to use one and the same pressure sensor to determine the ambient pressure and the pressure of the fluid to be delivered. To determine the ambient pressure, only the pressure sensor, which is in the fluid during normal operation, as described above, pumped free.

Vorzugsweise sind der Niveausensor, die Steuereinrichtung und die Kalibrierungseinrichtung Bestandteil eines Pumpenaggregates. Auf diese Weise wird ein einfach einzusetzendes bzw. zu montierendes Pumpenaggregat geschaffen, da sämtliche Steuer- und Messeinrichtungen in das Pumpenaggregat integriert sind. Vorzugsweise sind sämtliche Einrichtungen in das Pumpengehäuse integriert, so dass das Pumpenaggregat lediglich in einen Pumpensumpf eingesetzt bzw. eingehängt werden muss.Preferably, the level sensor, the control device and the calibration device Part of a pump unit. To this The way is an easy to use or to be assembled pump unit created since all control and measuring equipment in the pump unit are integrated. Preferably, all facilities integrated into the pump housing so that the pump unit merely inserted or suspended in a pump sump must become.

Der Drucksensor ist vorzugsweise oberhalb des Saugmundes der Pumpe angeordnet. Auf diese Weise wird verhindert, dass die Pumpe während des Freipumpens des Drucksensors trockenläuft, was ein späteres Wiederanlaufen erschweren oder verhindern würde. Es kann sichergestellt werden, dass auch während der Bestimmung des Umgebungsdruckes, wenn das Fluidniveau unter das Niveau des Drucksensors abgesenkt wird, der Saugmund ständig im Fluid gelegen ist.The pressure sensor is preferably above the suction mouth of the pump arranged. In this way, the pump is prevented from getting in the way the free pumping of the pressure sensor runs dry, resulting in a later restart complicate or prevent. It can be guaranteed that even during the determination of the ambient pressure, when the fluid level is lowered below the level of the pressure sensor is, the suction mouth is constantly located in the fluid.

Der Drucksensor ist vorzugsweise am Stator- oder Pumpengehäuse angebracht. Dies vereinfacht die Montage, da der Drucksensor nicht separat von der Pumpe an einer vorgegebenen Position im Pumpensumpf befestigt werden muss. Der Sensor befindet sich immer an einer vorgegebenen Position relativ zum Saugmund der Pumpe. Wenn der Drucksensor fest mit dem Stator- oder Pumpengehäuse verbunden bzw. an diesem angebracht ist, ist es zum Einsatz der Pumpe lediglich erforderlich, diese in den Pumpensumpf einzusetzen. The pressure sensor is preferably mounted on the stator or pump housing. This simplifies assembly, as the pressure sensor is not separate from the pump at a predetermined position in the sump must be attached. The sensor is always at one predetermined position relative to the suction port of the pump. If the Pressure sensor firmly connected to the stator or pump housing or attached to it, it is for use of the pump only necessary to insert these into the pump sump.

Weiter bevorzugt ist eine die Kalibrierungseinrichtung umfassende Steuereinrichtung in einem Klemmenkasten oder in dem Pumpen- oder Statorgehäuse angeordnet. Auf diese Weise wird eine kompakte Pumpe bzw. ein kompaktes Pumpenaggregat geschaffen, in welche(s) sämtliche Steuereinrichtungen integriert sind, so dass der Anschluss und die Inbetriebnahme der Pumpe vereinfacht wird.Further preferred is a control device comprising the calibration device in a terminal box or in the pump or stator housing arranged. In this way, a compact pump or created a compact pump unit, in which (s) all Control devices are integrated, so that the connection and the Commissioning the pump is simplified.

Der Drucksensor ist bevorzugt ein einseitig beaufschlagter Absolutdrucksensor. Dies ermöglicht eine einfache und kostengünstige Ausgestaltung des Drucksensors. Beispielsweise kann eine Membran in dem Drucksensor von einer Seite mit Druck beaufschlagt werden, während die erforderliche Elektronik zur Bestimmung der Membranauslenkung an der entgegengesetzten Seite der Membran geschützt vor dem Fluid angeordnet werden kann.The pressure sensor is preferably an unidirectional absolute pressure sensor. This allows a simple and inexpensive design of the pressure sensor. For example, a membrane in the Pressure sensor from one side to be pressurized while the required electronics for determining the diaphragm deflection the opposite side of the membrane protected from the fluid can be arranged.

Die Erfindung betrifft ferner die Verwendung eines einseitig beaufschlagten Drucksensors in einem Pumpensystem gemäß der vorangehenden Beschreibung, wobei der Drucksensor nur über elektrische Anschlussleitungen verfügt. Bei bekannten Differenzdrucksensoren ist es erforderlich, eine Schlauchleitung an die Oberfläche oberhalb des Fluidniveaus zu führen, um den Differenzdrucksensor von einer Seite her mit dem Umgebungsdruck zu beaufschlagen. Gemäß dem erfindungsgemäßen Verfahren und dem erfindungsgemäßen Pumpensystem ist dies nicht mehr erforderlich, vielmehr kann ein einseitig beaufschlagter Drucksensor in dem erfindungsgemäßen Pumpensystem verwendet werden.The invention further relates to the use of a unilaterally acted upon Pressure sensor in a pump system according to the preceding Description, where the pressure sensor only via electrical connection cables features. In known differential pressure sensors it is required, a tubing to the surface above the fluid level to guide the differential pressure sensor from one side with to apply the ambient pressure. According to the invention Method and the pump system according to the invention is this no longer necessary, but can act on one side Pressure sensor used in the pump system according to the invention become.

Nachfolgend wird die Erfindung beispielhaft anhand der beigefügten Figuren beschrieben. In diesem zeigt:

Fig. 1
ein Diagramm, welches den Ablauf eines Korrekturvorganges zeigt, und
Fig. 2
ein Diagramm, welches einen Ablauf zeigt, bei welchem keine Korrektur ausgeführt wird.
The invention will now be described by way of example with reference to the accompanying drawings. In this shows:
Fig. 1
a diagram showing the sequence of a correction process, and
Fig. 2
a diagram showing a procedure in which no correction is carried out.

Das erfindungsgemäße Verfahren und insbesondere das erfindungsgemäße Pumpensystem können überall dort eingesetzt werden, wo zu Mess- oder Steuerzwecken ein Differenzdruck zwischen einem Fluid und einem umgebenden Medium bestimmt werden muss. Bevorzugt wird das Verfahren in einer Pumpe eingesetzt, bei welcher über einem Drucksensor das Fluidniveau erfasst wird, um die Pumpe ein- und/oder auszuschalten. Um den genauen Fluidstand bestimmen zu können, ist es erforderlich, den Differenzdruck zwischen einem Druck in einer bestimmten Höhe in dem Fluid und den Umgebungsdruck zu bestimmen, da sonst Schwankungen des Umgebungsdruckes den ermittelten Wert für das Fluid- bzw. Flüssigkeitsniveau beeinflussen würden. Gemäß dem erfindungsgemäßen Verfahren werden dazu der Umgebungsdruck und der Druck in dem Fluid nicht gleichzeitig, sondern zu unterschiedlichen Zeitpunkten nacheinander bestimmt.The inventive method and in particular the inventive Pump system can be used wherever, too Measuring or control purposes, a differential pressure between a fluid and a surrounding medium must be determined. It is preferred the method used in a pump, in which over a Pressure sensor, the fluid level is detected to the pump on and / or off. To determine the exact fluid level is It requires the differential pressure between a pressure in a given Height in the fluid and to determine the ambient pressure otherwise fluctuations in the ambient pressure will be the value determined for the fluid level. According to the According to the invention, the ambient pressure and the pressure in the fluid is not simultaneous but different Times determined in succession.

Bei einer Tauchpumpe, wie sie beispielsweise zur Grundwasserabsenkung oder in Abwasserbrunnen eingesetzt wird, wird dazu zu vorbestimmten Zeitpunkten durch die Pumpe das Fluidniveau so weit abgesenkt, dass der als Niveausensor dienende Drucksensor freigepumpt wird, d. h. oberhalb des Fluidspiegels gelegen ist. In diesem Zustand kann der Drucksensor den Umgebungsdruck, d. h. den Luftdruck bestimmen. Anschließend läuft der Pumpensumpf wieder voll und der Drucksensor liegt wieder unterhalb des Fluidspiegels, so dass er den hydrostatischen Druck erfasst, welcher durch das über ihm stehende Fluid verursacht wird. Da zuvor der Umgebungsdruck bestimmt worden ist, kann nun die Druckdifferenz zwischen dem in dem Fluid erfassten Druck und dem Umgebungsdruck gebildet werden, so dass allein der durch das Fluid verursachte hydrostatische Druck erfasst wird und somit die Höhe des Fluidstandes bestimmt werden kann, um Ein- und/oder Ausschaltzeitpunkt der Pumpe zu bestimmen.In a submersible pump, as for example for groundwater lowering or used in sewage wells, becomes too pre-determined Time points lowered by the pump the fluid level so far in that the pressure sensor serving as a level sensor pumps out is, d. H. located above the fluid level. In this condition the pressure sensor can measure the ambient pressure, i. H. the air pressure determine. Then the pump sump runs full again and the Pressure sensor is again below the fluid level, so that he hydrostatic pressure detected, which by the standing above him Fluid is caused. Since previously the ambient pressure has been determined is now the pressure difference between the detected in the fluid Pressure and the ambient pressure are formed, so that alone the hydrostatic pressure caused by the fluid is detected and thus the height of the fluid level can be determined to input and / or To determine the switch-off time of the pump.

Als Drucksensor wird ein Absolutdrucksensor eingesetzt, welcher einseitig beaufschlagt ist.As a pressure sensor, an absolute pressure sensor is used, which one-sided is charged.

Anhand Fig. 1 wird nun der Ablauf eines Korrekturvorganges, d. h. der Ablauf der Bestimmung des Umgebungsdruckes näher beschrieben. In Fig. 1 ist die Höhe h des Flüssigkeitsniveaus in dem Pumpensumpf bzw. der vom Drucksensor erfasste Druck über die Zeit t aufgetragen. Die durchgezogene Linie 2 zeigt den Verlauf des vom Drucksensor abgegebenen Signals über die Zeit. Zunächst wird der Abpumpvorgang gestartet, so dass der Flüssigkeitsspiegel 2 bzw. das für Flüssigkeitsspiegel repräsentierende Drucksignal 2 abfällt, bis der Flüssigkeitsstand den Wert S2 erreicht. Der Wert S2 entspricht der Höhe S2, in welcher der Drucksensor an der Pumpe angebracht ist. Während dieses Abpumpvorganges erfasst die Steuereinrichtung der Pumpe eine durchschnittliche Absinkgeschwindigkeit, welche als punktierte Linie 4 in dem Diagramm gemäß Fig. 1 dargestellt ist. Wenn der Flüssigkeitsspiegel das Niveau S2 des Drucksensors erreicht und anschließend unterschreitet, erfasst der Drucksensor den Umgebungsdruck, so dass der vom Drucksensor erfasste Druck nicht weiter sinkt. Da die Steuereinrichtung über den erfassten Druck den Flüssigkeitsstand in dem Pumpensumpf bestimmt, scheint zu diesem Zeitpunkt aufgrund des konstanten Druckes für die Steuereinrichtung das Flüssigkeitsniveau konstant zu sein, was durch den horizontalen Verlauf des Graphen 2 auf der Höhe S2 während der Zeitintervalle t1 und t2 in Fig. 1 dargestellt ist.The course of a correction process, ie the sequence of the determination of the ambient pressure will now be described in more detail with reference to FIG. In Fig. 1, the height h of the liquid level in the pump sump or the pressure detected by the pressure sensor over the time t is plotted. The solid line 2 shows the course of the signal emitted by the pressure sensor over time. First, the pumping process is started so that the liquid level 2 or the pressure signal 2 representing the liquid level drops until the liquid level reaches the value S 2 . The value S 2 corresponds to the height S 2 , in which the pressure sensor is attached to the pump. During this Abpumpvorganges detects the control of the pump an average rate of descent, which is shown as a dotted line 4 in the diagram of FIG. When the liquid level reaches and then falls below the level S 2 of the pressure sensor, the pressure sensor detects the ambient pressure so that the pressure detected by the pressure sensor does not drop any further. Since the control device determines the liquid level in the pump sump via the detected pressure, the liquid level at this time seems to be constant due to the constant pressure for the control device, which is due to the horizontal course of the graph 2 at the height S 2 during the time intervals t 1 and t 2 is shown in Fig. 1.

Während des vorangehenden Abpumpvorganges wurde die durchschnittliche Sinkgeschwindigkeit des Flüssigkeitsspiegels dh/dt, dargestellt durch punktierte Linie 4, bestimmt. Um eine einwandfreie Bestimmung des Umgebungsdruckes gewährleisten zu können, soll der Flüssigkeitsspiegel unter das Niveau S2 auf das Niveau S1 abgesenkt werden. Um das Niveau S1 zu erreichen, muss somit der Flüssigkeitsspiegel ausgehend von dem Niveau S2 noch um die Höhe h1 abgesenkt werden. Aufgrund der zuvor ermittelten Sinkgeschwindigkeit dh/dt kann nun die Zeitspanne t1 bestimmt werden, in welcher die Pumpe mit konstanter Leistung weiterlaufen muss, so dass bei konstanter Sinkgeschwindigkeit das Flüssigkeitsniveau um das Maß h1 auf das Niveau S1 abgesenkt wird. Es gilt: t1 = h1/(dh/dt) During the preceding pump-down operation, the average sinking rate of the liquid level dh / dt represented by dotted line 4 was determined. In order to ensure a perfect determination of the ambient pressure, the liquid level should be lowered below the level S 2 to the level S 1 . In order to reach the level S 1 , therefore, the liquid level, starting from the level S 2, must still be lowered by the height h 1 . On the basis of the previously determined sinking speed dh / dt, the time span t 1 can then be determined in which the pump must continue to run at constant power, so that the liquid level is lowered by the amount h 1 to the level S 1 at a constant sinking speed. The following applies: t 1 = h 1 / (Dh / dt)

Nach Ablauf der Zeitspanne t1 wird die Pumpe abgeschaltet und der Flüssigkeitsspiegel steigt im Intervall t2 wieder an, bis er wieder das Niveau S2 erreicht. Beim Überschreiten des Niveaus S2 erfasst die Steuerung der Pumpe wieder eine Druckänderung, und das erfasste Signal für den Flüssigkeitspegel, welches durch die durchgezogene Linie 2 in Fig. 1 dargestellt wird, steigt nach Ablauf des Intervalls t2 wieder an.After the expiration of the time period t 1 , the pump is switched off and the liquid level rises again in the interval t 2 , until it again reaches the level S 2 . When the level S 2 is exceeded, the control of the pump again detects a pressure change, and the detected liquid level signal, which is represented by the solid line 2 in FIG. 1, rises again after the interval t 2 has elapsed.

In dem Intervall t2 wird die Messung des Umgebungsdruckes durchgeführt, sofern das Intervall t2 länger als ein vorgegebenes Intervall t2min ist. Wenn das Sensorsignal für einen kürzeren Zeitraum als t2min auf dem Wert S2 konstant bleibt, liegt ein Fall vor, bei welchem der Flüssigkeitszulauf in den Pumpensumpf den Flüssigkeitsablauf aufgrund des Abpumpvorganges durch die Pumpe kompensiert, so dass der Flüssigkeitsspiegel konstant bleibt. In diesem Zustand ist der Drucksensor nicht freigepumpt, obwohl er keine weitere Änderung des Druckes erfasst. Somit kann zu diesem Zeitpunkt keine Messung des Umgebungsdruckes durchgeführt werden. Wenn jedoch das Sensorsignal in einem Zeitraum t2 > t2min konstant auf dem Wert S2 bleibt, kann davon ausgegangen werden, dass das Flüssigkeitsniveau unter das Niveau S2 des Sensors abgesenkt wurde und der Sensor zu diesem Zeitpunkt somit frei, d. h. außerhalb des Fluids bzw. der Flüssigkeit liegt und den Umgebungsdruck erfassen kann.In the interval t 2 , the measurement of the ambient pressure is carried out, as long as the interval t 2 is longer than a predetermined interval t 2min . If the sensor signal remains constant at the value S 2 for a shorter period of time than t 2min , there is a case in which the liquid feed into the pump sump compensates for the liquid drain due to the pumping down operation so that the liquid level remains constant. In this condition, the pressure sensor is not pumped, although it detects no further change in pressure. Thus, no measurement of the ambient pressure can be performed at this time. If, however, the sensor signal remains constant at the value S 2 in a time interval t 2 > t 2min , it can be assumed that the liquid level has been lowered below the level S 2 of the sensor and the sensor is thus free at this time, ie outside the fluid or the liquid is and can detect the ambient pressure.

Im Anschluss an die Bestimmung des Umgebungsdruckes läuft der Pumpensumpf wieder voll, und nachfolgend ermittelte Druckwerte können auf Grundlage des Umgebungsdruckes korrigiert werden. Die Erfassung des Umgebungsdruckes erfolgt zu vorbestimmten Zeitpunkten, beispielsweise stündlich. Da Änderungen des Umgebungsdruckes wesentlich langsamer bzw. träger erfolgen als Änderungen des Flüssigkeitsniveaus, sind einzelne Messungen des Umgebungsdruckes in vorbestimmten Zeitintervallen ausreichend, um den in der Flüssigkeit bzw. dem Fluid erfassten Druck zu korrigieren, um die exakte Höhe des Flüssigkeitsstandes bestimmen zu können. Der Flüssigkeitsstand ist proportional zum Differenzdruck zwischen Fluiddruck und Umgebungsdruck.Following the determination of the ambient pressure of the runs Pump sump full again, and subsequently determined pressure values can be corrected based on the ambient pressure. The Detection of the ambient pressure takes place at predetermined times, for example, every hour. Because changes in ambient pressure much slower or slower than changes in the liquid level, are individual measurements of the ambient pressure in predetermined Time intervals sufficient to those in the liquid or To correct the pressure detected by the fluid to the exact height of the liquid level to be able to determine. The fluid level is proportional to the differential pressure between fluid pressure and ambient pressure.

Fig. 2 zeigt ein Diagramm entsprechend Fig. 1, welches einen weiteren Zustand veranschaulicht, in welchem keine Messung des Umgebungsdruckes vorgenommen wird. Wie anhand von Fig. 1 beschrieben, wird zunächst durch Starten der Pumpe das Flüssigkeitsniveau abgesenkt, was von dem Drucksensor erfasst wird, welcher einen Signalpegel 2 ausgibt. Zu einem Zeitpunkt T1 bleibt das Signal 2 in der Nähe des Niveaus S2 des Sensors konstant. Dies veranlasst die Steuereinrichtung zunächst zu der Annahme, dass das Niveau S2 erreicht bzw. unterschritten sei, so dass der Sensor freigepumpt ist. Folglich bestimmt sie nun, wie anhand von Fig. 1 erläutert ist, das Intervall t1, in welchem die Pumpe weiterlaufen muss, um den Flüssigkeitsspiegel um das vorbestimmte Maß h1 abzusenken. Nach Ablauf der Zeitspanne t1 wird die Pumpe abgeschaltet. In dem in Fig. 2 gezeigten Fall steigt nun nach Ablauf des Intervalls t1 das Signal 2 unmittelbar wieder an. Der Signalpegel 2 bleibt somit nicht, wie anhand von Fig. 1 erläutert, für eine Zeitdauer t2 > t2min konstant. Aus dem unmittelbaren Wiederanstieg des Signalpegels 2 kann nun geschlossen werden, dass tatsächlich nicht das Flüssigkeitsniveau unter das Niveau S2 abgesenkt worden ist, sondern dass lediglich ein Zulauf in den Pumpensumpf genau der durch die Pumpe abgepumpten Fluid- bzw. Flüssigkeitsmenge entsprochen hat, so dass in dem Intervall t1 der Signalpegel 2 konstant war. Aufgrund des Wiederanstiegs des Signalpegels 2 vor Ablauf der Zeitspanne t2min erkennt die Steuereinrichtung nun einen Fehler und führt keine Bestimmung des Umgebungsdruckes aus, sondern startet die Pumpe erneut, um den beschriebenen Vorgang von vorne zu beginnen und den Umgebungsdruck zu bestimmen.Fig. 2 shows a diagram corresponding to Fig. 1, which illustrates a further state in which no measurement of the ambient pressure is made. As described with reference to FIG. 1, the liquid level is first lowered by starting the pump, which is detected by the pressure sensor, which outputs a signal level 2. At a time T 1 , the signal 2 remains constant in the vicinity of the level S 2 of the sensor. This first causes the control device to assume that the level S 2 has been reached or fallen below, so that the sensor is pumped free. Consequently, it now determines, as explained with reference to FIG. 1, the interval t 1 , in which the pump must continue to lower the liquid level by the predetermined amount h 1 . After expiration of the time period t 1 , the pump is switched off. In the case shown in FIG. 2, the signal 2 then increases again immediately after expiration of the interval t 1 . The signal level 2 thus does not remain constant, as explained with reference to FIG. 1, for a time t 2 > t 2min . From the immediate increase in the signal level 2 can now be concluded that in fact not the liquid level has been lowered below the level S 2 , but that only an inlet into the pump sump has exactly met the pumped by the pump fluid or liquid quantity, so that in the interval t 1, the signal level 2 was constant. Due to the rise in the signal level 2 before the expiration of the time t 2min , the control device now detects an error and does not perform a determination of the ambient pressure, but starts the pump again to start the process described above and to determine the ambient pressure.

Durch das zuvor beschriebene Verfahren kann ohne zusätzliche Sensoren ziemlich genau derjenige Zustand bestimmt werden, in welchem der Drucksensor ausreichend freigepumpt ist, um den Umgebungsdruck zu bestimmen. Alternativ kann beispielsweise ein zweiter Sensor in Form eines Drucksensors oder eines anderen Niveau- oder Feuchtsensors vorgesehen sein, welcher erfasst, ob der zur Druckmessung verwendete Drucksensor oberhalb oder unterhalb des Flüssigkeitsspiegels gelegen ist. Dies ist wichtig, um mit ein und demselben Sensor den Umgebungsdruck und den Druck in dem Fluid zu unterschiedlichen Zeitpunkten bestimmen zu können und den in dem Fluid gemessenen Druck auf Grundlage des Umgebungsdruckes korrigieren zu können bzw. den Differenzdruck bestimmen zu können. Alternativ kann beispielsweise im Bereich des oberen Endes einer Tauchpumpe ein Drucksensor zur Bestimmung des Umgebungsdruckes nach Absenken des Fluidspiegels angeordnet und im Bereich des unteren Endes der Tauchpumpe ein weiterer Drucksensor zur Bestimmung des Fluiddruckes vorgesehen sein. Auch bei dieser Anordnung bewirkt die Druckmessung von Umgebungsdruck und Fluiddruck zu zwei verschiedenen Zeitpunkten, dass es nicht erforderlich ist, den Drucksensor zur Bestimmung des Umgebungsdruckes ständig oberhalb des Fluidspiegels zu halten, was zusätzliche Verbindungsleitungen erfordern würde. By the method described above can without additional sensors pretty much that state can be determined in which the pressure sensor is sufficiently pumped to the ambient pressure to determine. Alternatively, for example, a second sensor in shape a pressure sensor or other level or humidity sensor be provided, which detects whether the used for pressure measurement Pressure sensor located above or below the liquid level is. This is important to using one and the same sensor ambient pressure and the pressure in the fluid at different times to be able to determine and the pressure measured in the fluid Correct the basis of the ambient pressure or the differential pressure to be able to determine. Alternatively, for example, in Area of the upper end of a submersible pump a pressure sensor for determination the ambient pressure after lowering the fluid level arranged and in the region of the lower end of the submersible pump be provided further pressure sensor for determining the fluid pressure. Also in this arrangement, the pressure measurement of ambient pressure causes and fluid pressure at two different times that it is not necessary, the pressure sensor to determine the ambient pressure constantly above the fluid level to keep what extra Would require connecting lines.

Eine weitere beispielhafte Anwendungsmöglichkeit des erfindungsgemäßen Verfahrens ist eine Differenzdruckmessung in einem geschlossenen Heizungskreislauf, um den von einer Umwälzpumpe erzeugten Druck zu bestimmen. Hierzu wird, vorzugsweise an der Druckseite der Pumpe, zu einem Zeitpunkt, an dem die Pumpe abgeschaltet ist, ein erster Druck und zu einem anderen Zeitpunkt, zu dem die Pumpe eingeschaltet ist, ein zweiter Druck erfasst. Anschließend kann der Differenzdruck zwischen beiden erfassten Druckwerten bestimmt werden. Auch hier kann auf einen Differenzdrucksensor, welcher ständig den Differenzdruck zwischen Saug- und Druckseite der Pumpe erfasst, verzichtet werden. Es ist lediglich ein Absolutdrucksensor erforderlich, welcher die beiden zu vergleichenden oder voneinander zu subtrahierenden Drücke zu zwei verschiedenen Zeitpunkten bestimmt, wobei zuerst der erste oder auch zuerst der zweite Druckwert bestimmt werden kann.Another exemplary application of the invention Method is a differential pressure measurement in a closed Heating circuit to that generated by a circulating pump To determine pressure. For this purpose, preferably at the pressure side of Pump at a time when the pump is off first pressure and at another time when the pump is turned on is, a second pressure recorded. Subsequently, the differential pressure be determined between two detected pressure values. Again, a differential pressure sensor, which constantly the Differential pressure between suction and discharge side of the pump detected, omitted become. It is only an absolute pressure sensor required, which the two to be compared or subtracted from each other Pressures determined at two different times, where first the first or first of the second pressure value are determined can.

Claims (17)

  1. A method for detecting a differential pressure or for the correction of a pressure reading detected in a fluid, on the basis of another pressure, with which a pressure sensor serving as a level sensor in a pump is provided, characterised in that the ambient pressure is detected at one point in time, and the pressure of the fluid to be delivered by the pump at another point in time, and the pressure reading detected in the fluid is corrected on the basis of the first pressure, wherein for this, the pressure sensor for detecting the ambient pressure at the one point in time is brought into a position above the surface of the fluid to be delivered, and the pressure sensor for detecting the pressure of the fluid to be delivered at the other point in time is brought into a position below the surface of the fluid to be delivered.
  2. A method according to claim 1, characterised in that for determining the ambient pressure, the fluid level is lowered below the level (S2) of the pressure sensor, and the pressure sensor detects the ambient pressure for the correction of the pressure reading detected in the fluid.
  3. A method according to claim 2, characterised in that after reaching the level (S2) of the pressure sensor, the fluid level is lowered to a predefined value (S1) below the level (S2) of the pressure sensor.
  4. A method according to claim 3, characterised in that the fluid level after reaching the level (S2) of the pressure sensor is reduced further during a predefined time interval (t1),
  5. A method according to claim 4, characterised in that the time interval is computed on the basis of sinking speed (dh/dt) of the fluid level detected previously by the level sensor.
  6. A method according to one of the claims 3 to 5, characterised in that the pump after reaching the level (S2) of the pressure sensor is switched off after completion of the predefined time interval (t1), or on reaching a predefined fluid level (S1) below the level (S2) of the pressure sensor.
  7. A method according to one of the claims 1 to 6, characterised in that the detection of the ambient pressure is only effected when the fluid level remains below the level (S2) of the pressure sensor during a predefined time interval (t2).
  8. A method according to claim 7, characterised in that the pump is started again when a detection of the ambient pressure is not effected.
  9. A method according to one of the preceding claims, characterised in that a method step for determining the ambient pressure is started when the fluid level begins to sink at a predefined minimum speed.
  10. A method according to one of the preceding claims, characterised in that a detection of the pressure of the surrounding medium is carried out at predefined, preferably regular points in time.
  11. A pump system with a level sensor which comprises a pressure sensor for determining an absolute pressure in a fluid, and with a control means which switches the pump on and/or off in dependence on the readings of the level sensor, characterised in that the pump comprises a calibration means which controls the pump such that for calibration, the fluid level is lowered to below the level of the pressure sensor, so that this detects the ambient pressure, and corrects the pressure detected in the fluid on the basis of the detected ambient pressure at another point in time.
  12. A pump system according to claim 11, characterised in that the level sensor, the control means and the calibration means are a constituent of a pump assembly.
  13. A pump system according to claim 11 or 12, characterised in that the pressure sensor is arranged above the suction port of the pump.
  14. A pump system according to one of the claims 11 to 13, characterised in that the pressure sensor is attached on the stator housing or pump housing.
  15. A pump system according to one of the claims 11 to 14, characterised in that a control means comprising the calibration means is arranged in a terminal box or in the pump housing or stator housing.
  16. A pump system according to one of the claims 11 to 15, characterised in that the pressure senor is an absolute pressure sensor which is impinged on one side.
  17. The use of a pressure sensor impinged on one side in a pump system according to one of the claims 11 to 16, wherein the pressure sensor only has electrical connection conduits at its disposal.
EP02021526A 2002-09-26 2002-09-26 Method for detecting a differential pressure Expired - Lifetime EP1403522B1 (en)

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DE50205041T DE50205041D1 (en) 2002-09-26 2002-09-26 Method for detecting a differential pressure
EP02021526A EP1403522B1 (en) 2002-09-26 2002-09-26 Method for detecting a differential pressure
US10/670,953 US6981399B1 (en) 2002-09-26 2003-09-25 Method for detecting a differential pressure
CN03159838.2A CN1262821C (en) 2002-09-26 2003-09-26 Method for measuring differential pressure and pump system using the method

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Families Citing this family (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8540493B2 (en) 2003-12-08 2013-09-24 Sta-Rite Industries, Llc Pump control system and method
US7845913B2 (en) * 2004-08-26 2010-12-07 Pentair Water Pool And Spa, Inc. Flow control
US8602745B2 (en) 2004-08-26 2013-12-10 Pentair Water Pool And Spa, Inc. Anti-entrapment and anti-dead head function
US7686589B2 (en) 2004-08-26 2010-03-30 Pentair Water Pool And Spa, Inc. Pumping system with power optimization
US8480373B2 (en) 2004-08-26 2013-07-09 Pentair Water Pool And Spa, Inc. Filter loading
US8469675B2 (en) 2004-08-26 2013-06-25 Pentair Water Pool And Spa, Inc. Priming protection
US8019479B2 (en) 2004-08-26 2011-09-13 Pentair Water Pool And Spa, Inc. Control algorithm of variable speed pumping system
US7874808B2 (en) * 2004-08-26 2011-01-25 Pentair Water Pool And Spa, Inc. Variable speed pumping system and method
US7854597B2 (en) 2004-08-26 2010-12-21 Pentair Water Pool And Spa, Inc. Pumping system with two way communication
ES2688385T3 (en) 2008-10-06 2018-11-02 Pentair Water Pool And Spa, Inc. Method for operating a vacuum release safety system
US8436559B2 (en) * 2009-06-09 2013-05-07 Sta-Rite Industries, Llc System and method for motor drive control pad and drive terminals
US8564233B2 (en) * 2009-06-09 2013-10-22 Sta-Rite Industries, Llc Safety system and method for pump and motor
US9556874B2 (en) 2009-06-09 2017-01-31 Pentair Flow Technologies, Llc Method of controlling a pump and motor
US8727737B2 (en) 2010-10-22 2014-05-20 Grundfos Pumps Corporation Submersible pump system
WO2012078862A2 (en) 2010-12-08 2012-06-14 Pentair Water Pool And Spa, Inc. Discharge vacuum relief valve for safety vacuum release system
US9121270B2 (en) 2011-05-26 2015-09-01 Grundfos Pumps Corporation Pump system
US20120325022A1 (en) * 2011-06-24 2012-12-27 Veethree Pressure sensing liquid level sender
EP2774009B1 (en) 2011-11-01 2017-08-16 Pentair Water Pool and Spa, Inc. Flow locking system and method
US8752433B2 (en) * 2012-06-19 2014-06-17 Rosemount Inc. Differential pressure transmitter with pressure sensor
US9885360B2 (en) 2012-10-25 2018-02-06 Pentair Flow Technologies, Llc Battery backup sump pump systems and methods
US9353956B2 (en) * 2013-08-12 2016-05-31 Lawrence Halff Hot water recirculation system technologies
EP3156656B1 (en) 2015-10-16 2020-03-25 Grundfos Holding A/S Pump control method and pressure increasing device
EP3489517B1 (en) * 2017-11-24 2022-06-01 Xylem Europe GmbH Pump and method for controlling a pump
USD880670S1 (en) 2018-02-28 2020-04-07 S. C. Johnson & Son, Inc. Overcap
USD881365S1 (en) 2018-02-28 2020-04-14 S. C. Johnson & Son, Inc. Dispenser
USD872847S1 (en) 2018-02-28 2020-01-14 S. C. Johnson & Son, Inc. Dispenser
USD872245S1 (en) 2018-02-28 2020-01-07 S. C. Johnson & Son, Inc. Dispenser
USD853548S1 (en) 2018-05-07 2019-07-09 S. C. Johnson & Son, Inc. Dispenser
USD852938S1 (en) 2018-05-07 2019-07-02 S. C. Johnson & Son, Inc. Dispenser
CN109827703B (en) * 2019-03-27 2021-08-24 潍坊歌尔微电子有限公司 Air pressure detection method and device and washing machine
CN217511002U (en) * 2021-09-13 2022-09-30 特伦斯·安东尼·海兰德 Hand cleaning device

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1609092A1 (en) * 1965-11-22 1970-03-19 Helmut Pfeiffer Pneumatic control for pumps in faecal lifting systems
US4297081A (en) * 1979-11-05 1981-10-27 Irvin William A Liquid level control system
US4476707A (en) * 1982-04-08 1984-10-16 Bear Medical Systems, Inc. Gas flow measurement with detented chopper valve
JPS62192627A (en) * 1986-02-19 1987-08-24 Honda Motor Co Ltd Correcting method for air cylinder internal pressure of internal combustion engine
US4867871A (en) * 1988-12-09 1989-09-19 Bowne William C Sewage system discharge pump module
US5553481A (en) * 1994-03-04 1996-09-10 Nissei Plastic Industrial Co., Ltd. Pressure detecting apparatus of injection molding machine
AU1806897A (en) * 1995-12-13 1997-07-03 Baker Hughes Incorporated Method and apparatus for determining the profile of a sludge bed in a thickener

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US6981399B1 (en) 2006-01-03
CN1262821C (en) 2006-07-05
CN1497246A (en) 2004-05-19
EP1403522A1 (en) 2004-03-31
DE50205041D1 (en) 2005-12-29

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