US20180010604A1 - Eccentric Screw Pump And Method For Adapting The Operating State Of An Eccentric Screw Pump - Google Patents

Eccentric Screw Pump And Method For Adapting The Operating State Of An Eccentric Screw Pump Download PDF

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Publication number
US20180010604A1
US20180010604A1 US15/547,419 US201615547419A US2018010604A1 US 20180010604 A1 US20180010604 A1 US 20180010604A1 US 201615547419 A US201615547419 A US 201615547419A US 2018010604 A1 US2018010604 A1 US 2018010604A1
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United States
Prior art keywords
stator
screw pump
adjusting
eccentric screw
operating parameters
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Abandoned
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US15/547,419
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English (en)
Inventor
Stefan Voit
Christian Kneidl
Hisham Kamal
Christian Bindig
Mikael Tekneyan
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Netzsch Pumpen and Systeme GmbH
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Netzsch Pumpen and Systeme GmbH
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Assigned to NETZSCH PUMPEN & SYSTEME GMBH reassignment NETZSCH PUMPEN & SYSTEME GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BINDIG, Christian, VOIT, STEFAN, KAMAL, HISHAM, KNEIDL, CHRISTIAN, TEKNEYAN, MIKAEL
Publication of US20180010604A1 publication Critical patent/US20180010604A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/10—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member
    • F04C2/107—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member with helical teeth
    • F04C2/1071—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member with helical teeth the inner and outer member having a different number of threads and one of the two being made of elastic materials, e.g. Moineau type
    • F04C2/1073—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member with helical teeth the inner and outer member having a different number of threads and one of the two being made of elastic materials, e.g. Moineau type where one member is stationary while the other member rotates and orbits
    • F04C2/1075—Construction of the stationary member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/28—Safety arrangements; Monitoring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/10—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member
    • F04C2/107—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member with helical teeth
    • F04C2/1071—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member with helical teeth the inner and outer member having a different number of threads and one of the two being made of elastic materials, e.g. Moineau type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2240/00—Components
    • F04C2240/80—Other components
    • F04C2240/81—Sensor, e.g. electronic sensor for control or monitoring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2240/00—Components
    • F04C2240/80—Other components
    • F04C2240/811—Actuator for control, e.g. pneumatic, hydraulic, electric
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2270/00—Control; Monitoring or safety arrangements
    • F04C2270/17—Tolerance; Play; Gap
    • F04C2270/175—Controlled or regulated

Definitions

  • the present invention pertains to an eccentric screw pump and to a method for adapting the operating state of an eccentric screw pump.
  • the present invention pertains to an eccentric screw pump for conveying liquids and/or granular mediums.
  • Eccentric screw pumps are pumps for conveying a plurality of mediums, particularly thick-flowing, highly viscous and abrasive mediums such as, for example, sludges, liquid manure, mineral oil and greases.
  • the driven helical rotor rotates within the stator.
  • This stator consists of a housing with a helically coiled inner side.
  • the rotor carries out an eccentric rotational motion about the stator axis with its figure axis.
  • the outer screw i.e. the stator, is realized in the form of a double thread whereas the rotor screw is only single-threaded.
  • the rotor usually consists of a highly abrasion-resistant material such as steel.
  • the stator in contrast, consists of an elastic material such as rubber. Due to the special shapes of the rotor and the stator, sealed cavities are formed between the rotor and the stator, wherein said cavities move along axially during the rotation of the rotor and thereby convey the medium. In this case, the volume of the cavities is constant such that the medium being conveyed is not compressed.
  • eccentric screw pumps are not only capable of conveying fluids, but also solids.
  • the rotor In order to form the transport cavities and to convey the respective medium with the least backflow possible, the rotor contacts an inner wall of the stator, which consists of an elastic material, under the influence of pressure. Certain abrasion or wear of the stator occurs due to the motion of the typically metallic rotor within the stator, which typically consists of rubber or a similar material. This wear reduces the pressure-related contact force between the rotor and the stator and, in particular, no longer makes it possible to maintain the contact between the stator and the rotor along an uninterrupted helical contact line such that the performance of the eccentric screw pump drops. This particularly applies to eccentric screw pumps that have to overcome a great suction height or a high counterpressure. The stator therefore has to be exchanged and replaced within regular intervals.
  • the time of the stator exchange is determined, for example, by using sensors that detect the wear of the stator based on physical parameters.
  • DE 10157143 A1 describes a device for displaying maintenance intervals or remaining operating periods of eccentric screw pumps.
  • the sensors detect wear-related operating parameters that are acquired by a control unit. Based on these parameters, the control unit determines an expected value for the operating period or operating cycles before the next service has to be performed or certain components have to be exchanged.
  • DE 202005008989 discloses an eccentric screw pump, in which the operatability and the wear of the stator are monitored, wherein the stator is provided with at least one measuring transducer that makes it possible to measure compressions and/or motions of the stator or the elastic material during the course of the rotation of the rotor.
  • EP 0292594 A1 discloses a stator casing for eccentric screw pumps that is provided with a longitudinal slot and only features a tensioning device for generating pressure, as well as for readjusting the worn stator, in its pressure zone. The tension is partially distributed over the length of the stator casing by suitable reinforcing ribs.
  • DE 4403979 A1 discloses an adjustable stator for eccentric screw pumps with continuous longitudinal slots and longitudinal slots that end a short distance before the suction-side stator end.
  • a continuous slot advantageously follows each longitudinal slot.
  • the invention is based on the objective of achieving a simple and fast adaptation of a stator-rotor system to the respective operating states.
  • stator-rotor system and a method for adapting the operating state of a stator-rotor system, which respectively comprise the characteristics disclosed in the present claims.
  • Other advantageous embodiments are described in the dependent claims.
  • the invention concerns an eccentric screw pump with a stator-rotor system.
  • the stator-rotor system comprises a rotor with a rotor screw and a stator.
  • the stator-rotor system comprises a rotor with a single-threaded rotor screw and a stator with an internal double thread.
  • the stator is composed of at least two parts and comprises a support element and an elastomer part.
  • the elastomer part of the stator is arranged in a stator casing and typically not rigidly connected to the stator casing.
  • a fabric part or a screen structure that at least sectionally encompasses the elastomer part may also be used as support element instead of a stator casing.
  • the support element or the stator casing and the elastomer part are typically realized in the form of separate parts.
  • the support element or the stator casing encloses the elastomer part at least sectionally over its entire circumference.
  • the support element or the stator casing particularly encloses the majority of the elastomer part such that only the free outer end regions of the elastomer part protrude over the support element or the stator casing and are not enclosed thereby.
  • the stator particularly consists of a stator system of the type described in DE 102005042559 A1.
  • An axial deformation of the elastomer part is possible due to the lack of a rigid connection between the elastomer part and the support element or the stator casing.
  • the volume of the stator remains constant during a deformation. Consequently, an axial deformation of the elastomer part simultaneously leads to a change in the cross section of the oblong hole of the elastomer part, in which the rotor is guided.
  • the prestress i.e.
  • the contact pressure between the stator and the rotor can thereby also be varied in order to compensate the wear of the stator such that the adjustment or readjustment of the stator can also be used for adapting the prestress between the stator and the rotor of an eccentric screw pump to different operating conditions.
  • the stator-rotor system of the eccentric screw pump features an adjusting mechanism for varying and readjusting the prestress of the stator.
  • a different prestress of the stator-rotor system is required depending on the respective operating state of the eccentric screw pump.
  • the prestress is dependent, for example, on the viscosity of the conveyed product, product mixture or the like.
  • the operating state is determined, in particular, by means of different operating parameters such as the pressure, rotational speed, torque and/or other operating parameters.
  • the adjusting mechanism is coupled to a control system and activated and controlled thereby.
  • the control system particularly comprises at least one sensor for determining actual operating parameters of the stator-rotor system and/or the eccentric screw pump and a control unit for adjusting the adjusting mechanism.
  • the adjusting mechanism is coupled to at least one sensor for determining actual operating parameters of the stator-rotor system and/or the eccentric screw pump by means of a control unit.
  • the activation of the adjusting mechanism by the control unit takes place with consideration of the actual operating parameters determined by means of at least one sensor.
  • the inventive control mechanism establishes a correlation between different physical parameters of the stator-rotor system and the state of wear of the stator or the prestress between the stator and the rotor, respectively. For example, a correlation between the physical parameters pressure, torque, volumetric flow rate, rotational speed and/or viscosity and the state of wear of the stator or the prestress between the stator and the rotor is respectively established.
  • the most direct parameter that combines these correlations with one another is the state of stress in the elastomer material.
  • This stress can either be determined directly by means of a corresponding sensor system in the elastomer material or indirectly based on the reaction force of the elastomer on other components, for example the reaction force of the elastomer on the stator wall, particularly the support element or the stator casing, the reaction force of the elastomer on one of the end faces of the elastomer part, the reaction force of the elastomer on closures that consist, for example, of two shells and hold the support element or the stator casing together, etc.
  • a correlation between pressure, torque, volumetric flow rate, rotational speed and the existing prestress in the elastomer is established and a corresponding adjusting position for the adjustment of the adjusting mechanism, which should be suitable for adjusting the optimal operating point, is subsequently determined.
  • the physical operating parameters of the eccentric screw pump are measured anew in order to determine if the optimal operating state is reached. If the measured operating parameters do not correspond to the desired nominal parameters, an adjustment travel is calculated anew and the adjusting mechanism is correspondingly readjusted.
  • the actual control parameter is the predominant state of stress in the elastomer, which is measured, for example, in an indirect form and delivers an adjustment travel x and/or an adjustment direction with incremental approximation to the desired nominal value in combination with other operating parameters such as, for example, the rotational speed of the eccentric screw pump or the like.
  • the adjustment of the calculated adjustment travel x and/or the adjusting direction preferably takes place with incremental approximation. Consequently, an incremental approximation to the optimal adjustment of the adjusting mechanism particularly takes place.
  • the adjusting mechanism is adjusted by a defined amount if a nominal-actual deviation lies outside a defined tolerance range.
  • the inventive control algorithm defines the direction of the adjustment based on the nominal-actual comparison and the data stored within the control algorithm, wherein the extent of the adjustment corresponds to a predefined amount. In this way, in particular, an incremental approximation to the desired nominal value takes place until the measured nominal-actual deviation lies within the defined tolerance range.
  • the adjusting mechanism comprises two adjusting elements that are arranged on the stator-rotor system and variable with respect to their distance from one another.
  • the two adjusting elements In a first working position, the two adjusting elements are spaced apart from one another by a first distance whereas the two adjusting elements are in a second working position spaced apart from one another by a second distance, wherein the first distance differs from the second distance.
  • the cross section and the length of the elastomer part of the stator are changed in comparison with the cross section and the length of the elastomer part in the first working position.
  • a mechanical coupling and/or connection preferably exists between the adjusting mechanism and the stator, wherein such a coupling and/or connection particularly exists between the adjusting mechanism and the elastomer part of the stator.
  • a change in the cross section and the length of the elastomer part of the stator is realized by changing the relative distance between the two adjusting elements of the adjusting mechanism.
  • one of the adjusting elements is arranged on the stator-rotor system stationary and the other adjusting element is arranged on the stator-rotor system positionally variable.
  • the first adjusting element is arranged stationary, in particular, on the support element or the stator casing and the second adjusting element is arranged positionally variable on the elastomer part of the stator.
  • the first adjusting element is arranged stationary on a flange on a free end of the support element or the stator casing and the positionally variable second adjusting element is arranged on a free end of the elastomer part of the stator.
  • the control unit activates an actuator that causes a repositioning of the positionally variable second adjusting element and therefore a change in the relative distance between the positionally variable second adjusting element and the stationary first adjusting element.
  • the adjustment of the relative distance between the two adjusting elements may be realized in different ways. For example, wedge elements, tapered rings, mechanisms with spindle adjustment, cylinder-assisted mechanisms, etc. may serve as actuators.
  • At least one first sensor may be arranged on a stationary component of the eccentric screw pump that is assigned to the stator-rotor system, wherein said sensor can detect certain physical parameters of the stator-rotor system.
  • At least one second sensor may alternatively or additionally be arranged on the stator-rotor system, particularly on the elastomer part of the stator.
  • at least one third sensor may alternatively or additionally be arranged on the adjusting mechanism.
  • the at least one first sensor is designed for measuring the pressure, rotational speed, torque, temperature and/or volumetric flow rate of the eccentric screw pump whereas the at least one second sensor is designed for directly or indirectly measuring the prestress between the stator and the rotor of the stator-rotor system.
  • the second sensor may consist, for example, of a piezo element, a load cell or a dielectric elastomer.
  • the second sensor may also be designed for measuring the reaction forces of the elastomer material whereas the at least one third sensor may be designed for measuring the position of the positionally variable second adjusting element and/or for measuring the relative distance between the stationary first adjusting element and the positionally variable second adjusting element.
  • the invention furthermore concerns a method for adapting the operating state of an eccentric screw pump with an above-described stator-rotor system.
  • the actual operating state of the eccentric screw pump is initially established.
  • at least one actual physical operating parameter concerning the eccentric screw pump and/or at least one actual physical operating parameter concerning the elastomer part of the stator-rotor system and/or at least one actual physical operating parameter of the adjusting mechanism are determined with the aid of suitable sensors.
  • the actual operating parameters determined with the aid of the sensors are compared with known or desired nominal operating parameters. This comparison particularly takes place based on data stored in the control unit. If this comparison shows a deviation between the actual operating parameters and the nominal operating parameters, the adjusting mechanism is activated in order to adjust the stator. In this case, the adjustment of the new operating state is monitored by controlling at least one actual physical operating parameter.
  • a required adjustment of an adjustment travel of the adjusting mechanism is calculated if it is determined that the measured actual operating parameters deviate from the nominal operating parameters, wherein the adjusting mechanism is activated accordingly and the calculated adjustment travel is carried out, which in turn leads to a readjustment or adjustment of the stator, particularly to a change in the cross section and the length of the elastomer part of the stator.
  • the operating state is adjusted by means of an incremental approximation to an ideal operating point.
  • the control principle or the control algorithm is respectively based on the following functional principle: a volumetric flow rate is assigned to a first rotational speed of an eccentric screw pump. At a volumetric efficiency of 100%, the volumetric flow rate particularly would amount exactly to the volume, which is conveyed from the suction side to the pressure side of the eccentric screw pump by the individual transport elements (transport cavities) in accordance with the rotational speed.
  • the optimal adjustment of the operating point of the eccentric screw pump takes place as follows: an observation of the volumetric flow rate at a constant rotational speed over a certain adjusting range shows that this volumetric flow rate is at least largely constant over an extended range. However, the required driving torque is not constant. If the prestress is released, the torque drops due to the lower frictional losses caused by the reduced prestress.
  • the efficiency of the eccentric screw pump increases in the range, in which the volumetric flow rate does not change because no backflow or only slight backflow occurs as yet, wherein the efficiency of the eccentric screw pump does not drop until an operating point is reached, at which backflow increasingly occurs due to the reduced prestress.
  • the point of maximum efficiency can be concretely defined as follows: the ideal operating point of the pump lies exactly at the point, at which the prestress between the rotor and the stator is just sufficiently high such that no or only slight backflow occurs.
  • the ideal operating point consequently is the point, at which just as much prestress as necessary for generating the required counterpressure with the least possible backflow of the medium is generated in the rotor-stator system.
  • the control algorithm preferably utilizes the measuring principle described below: certain operating parameters of the eccentric screw pump are initially determined. For example, the pressure, rotational speed, torque (motor current) or other operating parameters are measured with the aid of suitable sensors.
  • the volumetric flow rate can also be measured, for example, by means of a volumetric flow meter, a measuring diaphragm or the like.
  • the adjusting mechanism now moves into an at least largely closed position, e.g. a position, in which the two adjusting elements are positioned as close to one another as possible. In this way, the rubber of the elastomer part is compressed such that the prestress in the stator-rotor system increases and backflow is minimized.
  • the adjusting mechanism is once again opened slowly and in a controlled fashion.
  • the volumetric flow rate initially remains largely constant up to a certain point.
  • the volumetric flow rate drops because backflow in the stator-rotor system increases.
  • the ideal operating point lies shortly before this dropping point.
  • the ideal operating point may also refer to a certain range, in which the eccentric screw pump performs with maximum efficiency.
  • the adjustment of the prestress is preferably carried out autonomously within certain time intervals by the adjusting system in the rotor-stator system. In this way, an active adjustment or adaptation to varying operating conditions of the pump can be ensured.
  • the prestress of the rotor-stator system can be increased based on the measured operating parameters and the incremental adjustment procedure until the maximum volumetric flow rate is reached. Once the maximum volumetric flow rate is reached, the prestress is once again increased by a defined number of adjusting increments. It is therefore ensured that the iBP was exceeded. The iBP is subsequently determined and adjusted by incrementally releasing the prestress. This procedure is repeated within defined time intervals. In this way, a reaction of the system to changing operating states is realized.
  • the actual operating state of the eccentric screw pump is established anew once a defined time period after the adjustment of the adjusting mechanism has elapsed and compared with the nominal operating parameters. In this way, the success of the adjustment can be verified.
  • the adjusting mechanism is activated and adjusted anew if a deviation between the actual operating parameters and the nominal operating parameters of the eccentric screw pump still exists, particularly a deviation outside a defined tolerance range. No additional adjustment takes place if the deviation between the actual operating parameters and the nominal operating parameters could be sufficiently reduced with the adjustment of the adjusting mechanism and therefore a readjustment or adjustment of the stator. Instead, the adjusted operating state of the eccentric screw pump is checked anew after another defined time period by means of the above-described sensor measurements.
  • the actual operating state of the eccentric screw pump is established anew after a defined time period by measuring the actual operating parameters and the actual operating parameters are once again compared with the nominal operating parameters.
  • the stator-rotor system is constantly monitored during its operation by regularly establishing the actual operating state within defined time intervals. In this way, a deviation from the desired operating state can be promptly adjusted and adapted during the operation of the eccentric screw pump.
  • the pressure, rotational speed, torque, temperature and/or volumetric flow rate of the eccentric screw pump is determined with the aid of suitable sensors.
  • the prestress between the rotor and the stator and/or the reaction forces of the elastomer material of the elastomer part are alternatively or additionally measured.
  • the position of at least one adjusting element of the adjusting mechanism and/or the relative distance between two adjusting elements of the adjusting mechanism can be determined with the aid of suitable sensors.
  • the adjustment of the adjusting mechanism is realized in that the relative distance between the two adjusting elements is increased or decreased.
  • the distance change between the two adjusting elements causes a change in the cross section and the length of the coupled elastomer part of the stator-rotor system.
  • the control mechanism calculates a nominal distance between the two adjusting elements based on physical parameters of the stator-rotor system determined with the aid of suitable sensors and, in particular, calculates the adjustment travel of the positionally variable second adjusting element. Subsequently, the adjusting mechanism is activated and the calculated position of the positionally variable second adjusting element is adjusted, particularly by adjusting the calculated distance between the two adjusting elements.
  • the physical operating parameters are determined anew after another time interval has elapsed. If the deviation from the desired actual value is reduced, this represents the new operating state of the eccentric screw pump.
  • the new operating state of the eccentric screw pump can be additionally approximated to the desired optimal operating state by means of additional readjustments or adjustments. Another adjustment of the adjusting mechanism takes place if the deviation from the desired actual value is not reduced.
  • the invention therefore concerns a stator-rotor system for an eccentric screw pump and a control of such a system.
  • the invention particularly concerns an automatic control system for varying the prestress between the stator and the rotor of an eccentric screw pump, i.e. between a soft component—the elastomer part—and a harder component—the support element, e.g. a so-called stator casing.
  • the automatic control of the prestress particularly leads to an automatic wear compensation such that a prolonged service life of the stator can be achieved. Due to the adjustment of the stator, the initial breakaway torque can be reduced with a defined procedure when the eccentric screw pump is switched on and/or off.
  • the automatic control system furthermore makes it possible to advantageously adapt the prestress between the stator and the rotor to the viscosity of the conveyed medium.
  • the method may comprise one or more characteristics and/or features of the above-described device.
  • the device may alternatively or additionally comprise individual or multiple characteristics and/or features of the described method.
  • FIG. 1 shows a schematic partial view of a conventional stator-rotor system (the prior art).
  • FIG. 2 shows a schematic partial view of a first embodiment of an inventive stator-rotor system with adjusting mechanism.
  • FIG. 3 schematically shows a sequence of a control mechanism for adjusting the stator-rotor system.
  • FIG. 4 shows the ideal operating point as a function of an adjustment travel of the adjusting mechanism.
  • FIG. 1 shows a schematic partial view of a conventional stator-rotor system 1 for an eccentric screw pump.
  • a system 1 comprises a typically metallic, single-threaded (not-shown) rotor and a stator 3 with a double thread.
  • the rotor carries out an eccentric rotational motion about the longitudinal stator axis X 3 with its figure axis.
  • the stator 3 comprises an elastomer part 4 and a stator casing 5 , wherein no rigid connection exists between the elastomer part 4 and the stator casing 5 .
  • FIG. 2 shows a schematic partial view of a first embodiment of an inventive stator-rotor system 10 with an adjusting mechanism 12 for respectively readjusting or adjusting the stator 3 .
  • the adjusting mechanism 12 comprises a stationary first adjusting element 13 and a positionally variable second adjusting element 14 .
  • a change in the distance between the two adjusting elements 13 , 14 causes a deformation of the elastomer and therefore a change in the cross section and/or the length of the elastomer part 4 of the stator 3 , as well as a respective readjustment or adjustment of the elastomer part 4 of the stator 3 .
  • a flange 23 on the stator casing 5 particularly serves as the stationary adjusting element 13 and an actuating element 24 arranged on the free end 8 of the elastomer part 4 serves as the positionally variable adjusting element 14 .
  • the adjusting mechanism 12 is coupled to a control system 30 and activated and controlled thereby.
  • the control system 30 comprises a control unit 32 and at least one sensor 35 for measuring physical operating parameters of the stator-rotor system 10 or the eccentric screw pump, respectively.
  • At least one first sensor 36 is particularly provided on the eccentric screw pump in order to measure the pump pressure, rotational speed, temperature and/or volumetric flow rate.
  • at least one second sensor 37 may be arranged on the elastomer part 4 and designed, for example, for determining the prestress between the rotor and the stator 3 or the reaction forces of the elastomer part.
  • At least one third sensor 38 may be provided on the adjusting mechanism 12 and designed for respectively detecting, for example, the position of the positionally variable adjusting element 14 or the relative distance between the stationary adjusting element 13 and the positionally variable adjusting element 14 .
  • the data acquired with the aid of the sensors is transmitted to the control unit 32 , which compares this data with nominal operating parameters and activates a corresponding adjustment of the adjusting system 12 if the measured actual operating parameters deviate from the nominal operating parameters, particularly an adjustment, during which the relative distance between the stationary adjusting element 13 and the positionally variable adjusting element 14 is changed such that the elastomer is deformed and the cross section and/or the length of the elastomer part 4 of the stator 3 changes.
  • FIG. 3 schematically shows a sequence of a control mechanism for adjusting the stator-rotor system 10 according to FIG. 2 .
  • the inventive control mechanism establishes a correlation between different physical parameters of the stator-rotor system 10 or the eccentric screw pump and the state of wear of the stator 3 or the prestress between the stator 3 and the rotor of the eccentric screw pump. For example, a correlation between the physical parameters pressure, volumetric flow rate, rotational speed and/or viscosity and the state of wear of the stator 3 or the prestress between the stator 3 and the rotor is established.
  • the most direct parameter that combines these correlations with one another is the state of stress in the elastomer material.
  • This stress can be to be determined directly by means of a corresponding sensor system 37 in the elastomer material or indirectly based on the reaction force of the elastomer on other components, for example on the stator wall, particularly the stator casing 5 , on the end face of the elastomer part 4 , on closure elements of the stator casing 5 , on the rotor of the stator-rotor system 10 , etc.
  • parameters that can be measured on the eccentric screw pump such as the pump pressure, the rotational speed, with which the eccentric screw pump is operated, the temperature, the volumetric flow rate of the conveyed medium, etc.
  • a correlation, for example, between pressure, volumetric flow rate, rotational speed and the required prestress is established with the aid of the inventive control algorithm and a corresponding adjustment travel for the adjustment of the adjusting mechanism 12 , which should be suitable for adjusting the optimal operating point, is subsequently determined. It is particularly conceivable to provide sensors 38 that determine the actual state of the adjusting system, particularly the position of the positionally variable adjusting element 14 or the relative distance between the stationary adjusting element 13 and the positionally variable adjusting element 14 , and/or sensors 38 that monitor the adjustment of the desired nominal position when the position of the positionally variable adjusting element 14 is adjusted.
  • the operating parameters determined with the aid of the sensors provide information on the operating state of the eccentric screw pump.
  • the control unit 32 compares these operating parameters with defined operating parameters that are stored, for example, in a characteristic diagram or in a table in the control unit 32 .
  • the system does not react if the comparison shows no deviation between the actual operating parameters and the nominal operating parameters. Instead, the actual operating parameters are measured anew after a time interval ⁇ t 1 and subjected to a comparison such that the operating state of the eccentric screw pump or the stator-rotor system 10 is regularly monitored or controlled.
  • the control unit 32 determines the required adjustment of the adjusting mechanism 12 based on a stored characteristic diagram or a stored table and activates the adjusting mechanism accordingly.
  • the physical operating parameters of the eccentric screw pump or the stator-rotor system 10 are measured anew once another time interval ⁇ t 2 has elapsed in order to once again determine whether the optimal operating state is respectively reached or maintained. If the measured operating parameters to not correspond to the desired nominal operating parameters, the control unit 32 once again calculates an adjustment travel and the adjusting mechanism 12 is readjusted accordingly.
  • the control algorithm particularly carries out an incremental adjustment of the type described below with reference to FIG. 4 .
  • FIG. 4 shows the adjustment of an ideal operating point as a function of an adjustment travel n of the adjusting mechanism.
  • a certain volumetric flow rate Q is assigned to a certain rotational speed of an eccentric screw pump.
  • the volumetric flow rate Q particularly would amount exactly to the volume, which is conveyed from the suction side to the pressure side of the eccentric screw pump by the individual transport elements (transport cavities) in accordance with the rotational speed.
  • the optimal adjustment of the ideal operating point iBP of the eccentric screw pump takes place as follows: an observation of the volumetric flow rate Q at a constant rotational speed over a certain adjustment travel n shows that this volumetric flow rate Q is nearly constant over an extended adjustment travel n. However, the required torque (not illustrated in the diagram in FIG. 4 ) is not constant. If the prestress is released by adjusting and/or repositioning the adjusting elements of the adjusting mechanism accordingly, the torque drops due to the lower frictional losses caused by the reduced prestress.
  • the efficiency of the eccentric screw pump increases in a typically broad adjusting range, in which at least largely no change of the volumetric flow rate Q takes place because no backflow or only slight backflow occurs as yet.
  • the efficiency of the eccentric screw pump does not drop until an operating point is reached, at which backflow increasingly occurs.
  • the point of maximum efficiency represents the ideal operating point iBP and can be concretely defined as follows: the ideal operating point of the pump lies exactly in the range of the adjustment travel n of the adjusting mechanism, in which the prestress between the rotor and the stator is just sufficiently high such that no backflow or largely no backflow occurs.
  • the ideal operating point iBP consequently is the point, at which just as much prestress as necessary for generating the required counterpressure with no backflow of the medium is generated in the rotor-stator system.
  • control algorithm utilizes the following measuring principle:

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rotary Pumps (AREA)
  • Details And Applications Of Rotary Liquid Pumps (AREA)
US15/547,419 2015-01-29 2016-01-29 Eccentric Screw Pump And Method For Adapting The Operating State Of An Eccentric Screw Pump Abandoned US20180010604A1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE102015101353.3 2015-01-29
DE102015101353 2015-01-29
DE102015112248.0A DE102015112248A1 (de) 2015-01-29 2015-07-28 Exzenterschneckenpumpe und Verfahren zum Anpassen des Betriebszustands einer Exzenterschneckenpumpe
DE102015112248.0 2015-07-28
PCT/DE2016/000033 WO2016119775A1 (de) 2015-01-29 2016-01-29 Exzenterschneckenpumpe mit einem automatischen verstellsystem und einstellverfahren

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US15/547,419 Abandoned US20180010604A1 (en) 2015-01-29 2016-01-29 Eccentric Screw Pump And Method For Adapting The Operating State Of An Eccentric Screw Pump

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EP (1) EP3250829B1 (de)
JP (1) JP2018507345A (de)
KR (1) KR20170096638A (de)
CN (1) CN107208630A (de)
AU (1) AU2016212425B2 (de)
DE (2) DE102015112248A1 (de)
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US20180238328A1 (en) * 2015-08-07 2018-08-23 Edwards Limited Pump comprising a proximity sensor
WO2024132945A1 (de) * 2022-12-23 2024-06-27 Seepex Gmbh Verfahren zur steuerung einer exzenterschneckenpumpe

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DE102018111120A1 (de) * 2018-05-09 2019-11-14 J. Wagner Gmbh Verfahren zum Betrieb einer Fördervorrichtung und Fördervorrichtung
DE102019130981A1 (de) * 2019-11-15 2021-05-20 Seepex Gmbh Exzenterschneckenpumpe
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CN112099220A (zh) * 2020-09-30 2020-12-18 青岛大学附属医院 一种新型病理检验用多向式显微镜托架
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DE102021131427A1 (de) 2021-11-30 2023-06-01 Vogelsang Gmbh & Co. Kg Exzenterschneckenpumpe mit Arbeitszustellung und Ruhezustellung sowie Verfahren zum Steuern der Exzenterschneckenpumpe
DE102022119147A1 (de) 2022-07-29 2024-02-01 Ruhr-Universität Bochum, Körperschaft des öffentlichen Rechts Verfahren zur Bestimmung oder Überwachung des Förderstroms einer Exzenterschneckenpumpe
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WO2024132945A1 (de) * 2022-12-23 2024-06-27 Seepex Gmbh Verfahren zur steuerung einer exzenterschneckenpumpe

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KR20170096638A (ko) 2017-08-24
EP3250829A1 (de) 2017-12-06
ZA201704734B (en) 2018-08-29
DE102015112248A1 (de) 2016-08-04
AU2016212425B2 (en) 2019-06-13
JP2018507345A (ja) 2018-03-15
AU2016212425A1 (en) 2017-07-13
CN107208630A (zh) 2017-09-26
DE112016000540A5 (de) 2017-12-21
WO2016119775A1 (de) 2016-08-04
EP3250829B1 (de) 2020-08-05
RU2017130347A (ru) 2019-03-01
RU2017130347A3 (de) 2019-03-01

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