EP3250829B1 - Eccentric screw pump having an automatic adjustment system and adjustment method - Google Patents

Description

The present invention relates to an eccentric screw pump and a method for adapting the operating state of an eccentric screw pump according to the features of the preambles of claims 1 and 5.

State of the art

The present invention relates to an eccentric screw pump for conveying liquid and / or granular media.

Eccentric screw pumps are pumps for pumping a variety of media, especially viscous, highly viscous and abrasive media such as sludge, liquid manure, petroleum and fats. The driven, coiled rotor rolls in the stator. This is a housing with a helical spiral inside. The rotor uses its figure axis to perform an eccentric rotary movement around the stator axis. The outer snail, i.e. the stator has the shape of a double-start thread, while the rotor worm is only single-start. The rotor is usually made of a highly abrasion-resistant material, such as steel. The stator, on the other hand, is made of an elastic material, for example rubber. The special shape of the rotor and stator creates sealed cavities between the rotor and stator, which move axially when the rotor rotates and convey the medium. The volume of the cavities is constant so that the medium is not squeezed. With a suitable design, eccentric screw pumps can not only convey fluids, but also solid bodies.

In order to form the delivery spaces and to be able to convey the respective medium with as little reflux as possible, the rotor is pressurized against an inner wall of the stator formed by elastic material. Due to the movement of the generally metallic rotor within the stator, which is usually made of rubber or a similar material, there is a certain amount of abrasion or wear on the stator. The wear on the pressurized contact force between the rotor and the stator is reduced, in particular the contact between the stator and the rotor along an uninterrupted line helical contact line can not be maintained, which reduces the performance of the eccentric screw pump. This applies in particular to eccentric screw pumps that have to overcome a high suction head or a high back pressure. For this reason, the stator must be replaced and replaced at regular intervals.

In order to determine the point in time at which the stator is replaced, sensors are used, for example, which detect the wear of the stator based on physical parameters. The DE 10157143 A1 describes a display of maintenance intervals or remaining operating times of eccentric screw pumps. The sensors record operating parameters relevant to wear, which are recorded by a control unit. The control unit uses these parameters to determine an expected value of the operating time or of operating cycles until the next maintenance is due or the replacement of certain parts.

The DE 202005008989 discloses an eccentric screw pump with a monitoring of the functionality and wear of the stator, the stator being assigned at least one measuring sensor with which compressions and / or movements of the stator or the elastic material can be measured in the course of the rotation of the rotor.

Other options for sensory monitoring of the stator state are described, for example, in the documents JP 2011112041 A , JP 2010281280 A , JP 2009235976 A and JP 20101104 A described.

So that a stator can be used for longer, adjustable stators are also known. DE 3433269 A1 describes a stator jacket with tensioning devices in the form of tension bolts, which are distributed over the entire axial length of the stator jacket. This causes a significant increase in the weight of the stator-rotor system. In addition, all clamping devices must be retightened individually for adjustment.

EP 0292594 A1 discloses a stator jacket for eccentric screw pumps provided with a longitudinal slot, which has a tensioning device for generating pressure and for adjusting when the stator wears only in its pressure range. The voltage is partially distributed over the length of the stator sheath using suitable reinforcing ribs.

DE 4312123 A1 describes a stator jacket with several longitudinal slots that simplify the adjustment. So that readjustment can be carried out better in the area of the pressure-side end of the stator, the slots end shortly before the end of the suction-side end of the stator and only run freely at the pressure-side end.

DE 4403979 A1 discloses an adjustable stator for eccentric screw pumps with continuous longitudinal slots and longitudinal slots that end at a short distance in front of the suction-side end of the stator. Appropriately, a longitudinal slot is followed by a continuous slot.

The document WO 2016/034341 A1 describes an eccentric screw pump with at least one stator made of an elastic material and a rotor that can be rotated in the stator. The stator is at least partially surrounded by a stator jacket, which is designed as a longitudinally divided jacket from at least two jacket segments, which form a stator clamping device with which the stator can be clamped against the rotor in the radial direction. The stator tensioning device has one or more movable adjusting elements which act on the shell segments for adjusting and tensioning the stator. In addition, the end regions of the elastomer part of the stator protrude beyond the jacket segments.

The document WO 01/98660 A2 discloses a rotor-stator system that provides an adjustable rotor and / or stator so that the press fit and / or the clearance can be adjusted. The rotor and / or the inner cross section of the stator are tapered in the longitudinal direction in order to achieve a difference in the fit between the rotor and the stator by longitudinally adjusting their relative position.

The disclosure GB 2 338 268 A also describes an eccentric screw pump in which the play between a stator and a rotor can be adjusted to compensate for wear. The rotor is rotatably received in a helical bore of the elastomeric stator, which is located in a cylindrical housing that has axial slots at equiangular intervals around its circumference. An annular chamber surrounds the housing and is connected to an injector pump. A pressure sensor in the chamber is connected to a regulator of the pump. Wear results in an excessive distance between the stator and rotor, which is indicated by a drop in pressure. For adjustment, the chamber is filled with hydraulic fluid until the stator housing presses the elastomeric stator onto the rotor again.

The document DD 279 043 A1 describes a stator for an eccentric screw pump that can be re-tensioned and enables a correction of wear-related gap losses along the helically wound stator interior. The stator is molded from an elastomer and has a conical outer surface. The stator is further arranged axially retensionable in a sleeve. While a connection thread for a pump riser pipeline is provided on the head side, the sleeve has an external thread on the foot side, into which a clamping nut engages, for the securing of which a threaded ring is provided. Finally, the stator is re-tensioned using the tension nut.

The object of the invention is to achieve a simple and quick adaptation of a stator-rotor system to the operating conditions.

The above object is achieved by a stator-rotor system and a method for adapting the operating state of a stator-rotor system, which comprise the features in claims 1 and 5. Further advantageous embodiments are described by the subclaims.

description

The invention relates to an eccentric screw pump with a stator-rotor system. The stator-rotor system comprises a rotor with a rotor screw and a stator. According to a preferred embodiment, the stator-rotor system comprises a rotor with a single-start rotor screw and a stator with a two-start internal thread. The stator is constructed in at least two parts and comprises a support element and an elastomer part. According to one embodiment of the invention, the elastomer part of the stator is arranged in a stator shell and generally has no fixed connection to the stator shell. Instead of a stator sheath, a fabric part or a lattice structure that at least partially encompasses the elastomer part can also be used as a support element. This means that the support element or the stator casing and the elastomer part are generally designed as separate parts. The support element or the stator sheath completely surrounds the elastomer part at least in some areas. In particular, the support element or the stator casing surrounds the majority of the elastomer part, so that only the free outer end regions of the elastomer part protrude beyond the support element or the stator casing and are not enclosed by the latter.

In particular, the stator is a stator system as shown in FIG DE 102005042559 A1 is described. Due to the lack of a firm connection between the elastomer part and the support element or stator jacket, axial deformation of the elastomer part is possible. In the event of deformation, the volume of the stator remains the same. As a result, an axial deformation of the elastomer part also leads to a change in the cross section of the elongated hole of the elastomer part in which the rotor is guided. As a result, in addition to compensating for the wear of the stator, the preload, that is to say the contact pressure between the stator and rotor, can be varied, that is to say the adjustment or adjustment of the stator can also be used to adapt the preload between the stator and rotor of an eccentric screw pump to different operating conditions .

The stator-rotor system of the eccentric screw pump has an adjustment mechanism for varying and adjusting the preload of the stator. Depending on the operating state of the eccentric screw pump, a different preload of the stator-rotor system is necessary. The preload is dependent, for example, on the viscosity of the product being conveyed, product mixture or the like. The operating state is determined in particular by means of different operating parameters, for example pressure. Speed, torque and / or other operating parameters determined. The adjustment mechanism is coupled to a control system and is controlled and controlled by this. In particular, the control system comprises at least one sensor for determining actual operating parameters of the stator-rotor system and / or the eccentric screw pump and a control for setting the adjustment mechanism. This means that the adjustment mechanism is coupled via a control to at least one sensor for determining actual operating parameters of the stator-rotor system and / or the eccentric screw pump. The adjustment mechanism is controlled by the control system taking into account the actual operating parameters determined by means of at least one sensor.

The control mechanism according to the invention establishes a connection between various physical parameters of the stator-rotor system and the state of wear of the stator or the pretension between the stator and rotor. For example, a relationship is established between the physical parameters pressure, torque, flow rate, speed and / or viscosity as well as the state of wear of the stator or the preload between the stator and rotor. The most direct parameter that combines these relationships is the state of tension in the elastomer material. This can either be done directly via a Corresponding sensors in the elastomer material are determined, or determined indirectly via the reaction forces of the elastomer on other components, for example via the reaction forces of the elastomer on the stator wall, in particular the support element or the stator jacket, or via the reaction force of the elastomer on one of the end faces of the elastomer part, about the reaction force of the elastomer to closures, which for example consist of two shells and hold the support element or the stator casing together, etc.

With the aid of the control algorithm according to the invention, a correlation is established, for example, from pressure, torque, flow, speed and the pre-tension in the elastomer, and a corresponding adjustment position for adjusting the adjustment mechanism is then determined, which should be suitable for setting the optimum operating point. After automatic adjustment of the adjustment mechanism, the physical operating parameters of the eccentric screw pump are measured again and from this it is determined whether the optimal operating state has been reached. If the measured operating parameters do not correspond to the desired target parameters, an adjustment path is calculated again and the adjustment mechanism is set accordingly.

According to a preferred embodiment of the invention, the actual control parameter is the stress state prevailing in the elastomer, which is measured, for example, in an indirect form and in combination with other operating parameters, such as the speed of the eccentric screw pump or the like, an adjustment path x and / or an adjustment direction with incremental approximation outputs to the desired value.

Provision is preferably made for the calculated adjustment path x and / or the adjustment direction to be set with incremental approximation. In particular, a step-by-step approach to the optimal adjustment of the adjustment mechanism takes place. In the event of a target / actual deviation outside of a specified tolerance, the adjustment mechanism is adjusted by a specified amount. The control algorithm according to the invention determines the direction of the adjustment based on the target / actual comparison and the data stored within the control algorithm, the size of the adjustment corresponds to a predetermined amount. In this way, an in particular incremental approximation to a desired target value takes place until the measured target / actual deviation lies within the defined tolerance.

According to the invention, the adjustment mechanism comprises two adjusting elements which are arranged on the stator-rotor system and are variable in relation to one another. In a first working position, the two setting elements are at a first distance from one another and in a second working position, the two setting elements are at a second distance from one another, the first distance being not equal to the second distance. In the second working position, the cross section and the length of the elastomer part of the stator are changed compared to the cross section and the length of the elastomer part in the first working position.

According to the invention there is a mechanical coupling and / or connection between the adjusting mechanism and the stator, in particular there is such a coupling and / or connection between the adjusting mechanism and the elastomer part of the stator. By changing the relative distance between the two adjusting elements of the adjusting mechanism, the cross section and the length of the elastomer part of the stator are changed.

According to the invention, it is provided that one of the setting elements is arranged in a fixed position on the stator-rotor system and the other setting element is arranged in a variable position on the stator-rotor system. The first setting element is arranged in a stationary manner on the support element or the stator jacket and the second setting element is arranged in a variable position on the elastomer part of the stator. According to a preferred embodiment, the first setting element is arranged in a fixed position on a flange at a free end of the support element or stator casing and the second position-variable setting element is arranged at a free end of the elastomer part of the stator.

According to one embodiment of the invention, the control activates an actuator which brings about a repositioning of the second position-variable setting element and thus causes a change in the relative distance between the second position-variable setting element and the first fixed setting element. The relative distance between the two setting elements can be set in different ways. For example, wedge elements, wedge rings, mechanisms with spindle adjustment, cylinder-supported mechanisms, etc. can serve as actuators.

According to one embodiment of the invention, at least one first sensor can be attached to a stationary component of the stator-rotor system Eccentric screw pump can be arranged, which can detect certain physical parameters of the stator-rotor system. Alternatively or additionally, at least one second sensor can be arranged on the stator-rotor system, in particular on the elastomer part of the stator. Furthermore, as an alternative or in addition, at least one third sensor can be arranged on the adjustment mechanism.

For example, the at least one first sensor is designed for measuring the pressure, speed, torque, temperature and / or the volume flow of the eccentric screw pump, while the at least one second sensor is designed for direct or indirect measurement of the preload between the stator and the rotor of the stator-rotor. Systems is trained. The second sensor can be, for example, a piezo element, a load cell or a dielectric elastomer. The second sensor can also be designed such that the reaction forces of the elastomer material can be measured, while the at least one third sensor for measuring the position of the second position-variable setting element and / or for measuring the relative distance between the first fixed setting element and the second position variable Adjustment element can be formed.

The invention further relates to a method for adapting the operating state of an eccentric screw pump with a stator-rotor system described above.

First, the actual operating status of the eccentric screw pump is queried. Here, at least one physical actual operating parameter relating to the eccentric screw pump and / or at least one physical actual operating parameter relating to the elastomer part of the stator-rotor system and / or at least one physical actual operating parameter of the adjusting mechanism are determined by sensors. The sensor-determined actual operating parameters are then compared with known or desired target operating parameters. The comparison is made in particular on the basis of data stored in the control. If a discrepancy between the actual operating parameters and the target operating parameters is determined in the comparison, the adjustment mechanism for adjusting the stator is activated. The setting of the new operating state is monitored by checking at least one physical actual operating parameter.

According to a first preferred embodiment, when a deviation is ascertained between the measured actual operating parameters and the target operating parameters calculates a necessary adjustment of an adjustment path of the adjustment mechanism and controls it accordingly and adjusts the calculated adjustment path, which leads to an adjustment or adjustment of the stator, in particular to a change in the cross section and the length of the elastomer part of the stator.

According to an alternative embodiment, the operating state is set by an incremental approximation to an ideal operating point. The control principle or control algorithm is based on the following functional principle: A volume flow is assigned to a first speed of an eccentric screw pump. In particular, with a 100% volumetric efficiency, the volume flow would be exactly the volume that is conveyed by the individual conveying elements (conveying chambers) according to the speed from the suction side to the pressure side of the eccentric screw pump.

The optimal setting of the operating point of the eccentric screw pump is now carried out as follows: If you consider the volume flow at a constant speed over a certain adjustment range, you can see that it is at least largely constant over a longer range. However, the drive torque required for this is not constant. If the preload is released, the torque drops due to the lower friction losses due to the reduced preload. The efficiency of the eccentric screw pump increases in the area where there is no change in the volume flow because there is no or only a small backflow. Only when an operating point is reached in which backflow increasingly occurs due to the reduced preload, does the efficiency of the eccentric screw pump decrease . The point of highest efficiency can be descriptively described as follows: The ideal operating point of the pump is precisely where there is just enough pre-tension between the rotor and stator, so that there is little or no backflow. The ideal operating point is therefore the point at which just as much preload is generated in the rotor-stator system as is necessary to be able to generate the necessary back pressure with the least possible backflow of the medium.

This mode of operation is used for the control algorithm, with an incremental approximation in particular in order to set the ideal operating state. According to one embodiment of the invention, the control algorithm preferably uses the measuring principle described below: First certain operating parameters of the eccentric screw pump are recorded. For example, the pressure, the speed, the torque (motor current) or other operating parameters are measured by means of suitable sensors. For example, the volume flow can also be recorded by means of a volume flow meter, a measuring orifice or the like.

The adjustment mechanism now moves into an at least largely closed position, e.g. in which the two setting elements are maximally approximated to one another. As a result, the rubber of the elastomer part is pressed, so that the pretension in the stator-rotor system increases, and a backflow is thereby minimized.

After it has been ensured that an area of sufficient compression is set, the adjustment mechanism is opened slowly and in a controlled manner. The volume flow initially remains largely constant up to a certain point. At a certain point, the volume flow drops because the backflow in the stator-rotor system increases. The ideal operating point is just before this break-in point. The ideal operating point can also be seen as a certain range in which the eccentric screw pump shows its best efficiency.

The presetting is preferably carried out independently at certain time intervals by the adjustment system within the rotor-stator system. This ensures an active setting or adaptation to varying operating conditions of the pump.

Alternatively, the bias of the rotor-stator system can be increased until the maximum volume flow is reached on the basis of the measured operating parameters and the incremental adjustment procedure. When a maximum of the volume flow is reached, the preload is increased again by a fixed number of adjustment increments. This ensures that the iBP has been exceeded. The iBP is determined and set by subsequently releasing the preload incrementally. This procedure is repeated at fixed intervals. It is thus reacted to changing operating conditions.

According to a preferred embodiment, following the adjustment of the adjustment mechanism, after a defined period of time, the actual operating state of the eccentric screw pump is queried again and compared with the target operating parameters. The success of the adjustment is checked. Consists If there is still a discrepancy between the actual operating parameters and the target operating parameters of the eccentric screw pump, in particular a discrepancy outside of a specified tolerance range, the adjustment mechanism is triggered and adjusted again. If the deviation between the actual operating parameters and the target operating parameters could be sufficiently reduced by adjusting the adjustment mechanism and thus adjusting or adjusting the stator, no further adjustment is made. Instead, the set operating state of the eccentric screw pump is checked again after a defined additional period of time by means of the sensor measurements described above.

If, on the other hand, when the actual operating state of the eccentric screw pump is queried for the first time, no deviation between the actual operating parameters and the target operating parameters is determined, in particular no deviation outside the defined tolerance range, the actual operating state of the eccentric screw pump is queried again after a defined period of time Measurement of the actual operating parameters and again a comparison of the same with the target operating parameters. The stator-rotor system is continuously monitored during operation by regular polling at defined intervals. In this way, a deviation from the desired operating state can be promptly readjusted and adjusted during operation.

According to one embodiment of the invention, the pressure, the speed, the torque, the temperature and / or the volume flow of the eccentric screw pump is determined by sensors. Alternatively or additionally, the pretension between the rotor and stator and / or the reaction forces of the elastomer material of the elastomer part are measured. Furthermore, 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 by sensors.

Since the adjusting mechanism comprises two variable-distance adjusting elements, the adjusting mechanism is adjusted according to the invention by increasing or decreasing the relative distance between the two adjusting elements. The change in distance 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. Here, the control mechanism calculates a target distance between the two setting elements and on the basis of sensor-determined physical parameters of the stator-rotor system in particular calculates the adjustment path of the second position-variable setting element. The adjustment mechanism is then actuated and the calculated position of the second position-variable setting element is set, in particular the set distance between the two setting elements is thereby set. After a further time interval, the physical operating parameters are determined again. If the deviation from the desired actual value is reduced, this represents the new operating state of the eccentric screw pump. By further adjustment or adjustment, the new operating state of the eccentric screw pump can be further approximated to the desired optimal operating state. If the deviation from the desired actual value is not reduced, the adjustment mechanism is adjusted further. The invention therefore relates to a stator-rotor system for an eccentric screw pump and to a control system of such a system. The invention relates in particular to an automatic control system for varying the preload between the stator and the rotor of an eccentric screw pump, that is to say between a soft component - the elastomer part - and a harder component - the support element, for example a so-called stator jacket. A major advantage is that the eccentric screw pump can be operated at the optimum operating point at any time, which leads to a significant increase in the energy efficiency of the stator-rotor system.

The automatic regulation of the preload leads in particular to automatic wear compensation, so that a stator can be used longer. The breakaway torque can be reduced by setting the stator by means of a defined procedure when switching on and / or off.

Furthermore, the prestress between the stator and the rotor can advantageously be adapted to the viscosity of the conveyed medium with the automatic control system.

As an alternative or in addition to the features described, the method can comprise one or more features and / or properties of the device described above. As an alternative or in addition, the device can also have one or more features and / or properties of the described method.

Figure description

• Figur 1 zeigt eine schematische Teil- Ansicht eines bekannten Stator- Rotor-Systems (Stand der Technik).
• Figur 2 zeigt eine schematische Teil- Ansicht einer ersten Ausführungsform eines erfindungsgemäßem Stator- Rotor- Systems mit Verstellmechanismus.
• Figur 3 zeigt schematisch einen Ablauf eines Regelmechanismus zum Einstellen des Stator- Rotor- Systems.
• Figur 4 stellt den idealen Betriebspunkt in Abhängigkeit von einem Verstellweg des Verstellmechanismus dar.

In the following, exemplary embodiments are intended to explain the invention and its advantages with reference to the attached figures. The size relationships of the individual elements to one another in the figures do not always correspond to the real size relationships, since some shapes are simplified and other shapes are shown enlarged in relation to other elements for better illustration.

• Figure 1 shows a schematic partial view of a known stator-rotor system (prior art).
• Figure 2 shows a schematic partial view of a first embodiment of a stator-rotor system according to the invention with adjustment mechanism.
• Figure 3 shows schematically a flow of a control mechanism for adjusting the stator-rotor system.
• Figure 4 represents the ideal operating point depending on an adjustment path of the adjustment mechanism.

Identical reference numerals are used for identical or identically acting elements of the invention. Furthermore, for the sake of clarity, only reference numerals are shown in the individual figures which are necessary for the description of the respective figure. The illustrated embodiments merely represent examples of how the device according to the invention or the method according to the invention can be designed and do not constitute a final limitation.

Figure 1 shows a schematic partial view of a known stator-rotor system 1 for an eccentric screw pump. Such a system 1 comprises a generally metallic, single-start spiral rotor (not shown) and a stator 3 with a two-start thread. When the eccentric screw pump is operated, the rotor executes an eccentric rotary movement about the longitudinal axis X3 of the stator with its figure axis. The stator 3 comprises an elastomer part 4 and a stator jacket 5, there being no fixed connection between the elastomer part 4 and the stator jacket 5.

Figure 2 shows a schematic partial view of a first embodiment of a stator-rotor system 10 according to the invention with adjusting mechanism 12 for adjusting or adjusting the stator 3. The adjusting mechanism 12 comprises a first fixed adjusting element 13 and a second position variable Adjustment element 14. A change in the distance between the two adjustment elements 13, 14 causes a deformation of the elastomer and thus a change in the cross section and / or the length of the elastomer part 4 of the stator 3 and thus a readjustment or adjustment of the elastomer part 4 of the stator 3 Flange 23 on the stator jacket 5 as a fixed adjusting element 13 and an actuating element 24 arranged at the free end 8 of the elastomer part 4 serves as a variable-position adjusting element 14.

The adjustment mechanism 12 is coupled to the control system 30 and is controlled and controlled by this. The control system 30 comprises a controller 32 and at least one sensor 35 for measuring physical operating parameters of the stator-rotor system 10 or the eccentric screw pump. In particular, at least one first sensor 36 is provided on the eccentric screw pump for measuring the pump pressure, the speed, the temperature and / or the volume flow. Furthermore, at least one second sensor 37 can be arranged on the elastomer part 4, which for example determines the pretension between the rotor and stator 3 or reaction forces of the elastomer material. In addition, at least one third sensor 38 can be provided on the adjustment mechanism 12, which detects, for example, the position of the position-variable adjustment element 14 or the relative distance between the fixed adjustment element 13 and the position-variable adjustment element 14. The sensor-determined data is transmitted to the controller 32, which compares it with the target operating parameters and, in the event of a deviation between the measured actual operating parameters and the target operating parameters, controls a corresponding adjustment of the adjustment system 12, in particular an adjustment in which the relative distance between the fixed setting element 13 and the variable position setting element 14 is changed, whereby a deformation of the elastomer and thus a change in the cross section and / or the length of the elastomer part 4 of the stator 3 is effected.

Figure 3 schematically shows a sequence of a control mechanism for adjusting the stator-rotor system 10 according to Figure 2 . The control mechanism according to the invention establishes a connection between different physical operating parameters of the stator-rotor system 10 or the eccentric screw pump and the state of wear of the stator 3 or the pretension between the stator 3 and the rotor of the eccentric screw pump. For example, a relationship between the physical parameters pressure, flow rate, speed and / or viscosity and the state of wear of the stator 3 or the bias voltage between stator 3 and rotor. The most direct parameter that combines these relationships is the state of tension in the elastomer material. This can be determined either directly via a corresponding sensor system 37 in the elastomer material, or indirectly via the reaction force of the elastomer on other components, for example on the stator wall, in particular the stator jacket 5, or the end face of the elastomer part 4, on closure elements of the stator jacket 5, on the Rotor of the stator-rotor system 10 etcetera.

As an alternative and / or in addition, measurable parameters can be used on the eccentric screw pump, for example the pump pressure, the speed at which the eccentric screw pump is operated, the temperature, the volume flow of the pumped medium, etc.

With the aid of the control algorithm according to the invention, a correlation is established, for example from pressure, flow, speed and the required preload, and a corresponding adjustment path for adjusting the adjustment mechanism 12 is then determined, which should be suitable for setting the optimal operating point. In particular, sensors 38 can be provided which determine the actual state of the adjustment system, in particular the position of the position-variable adjustment element 14 or the relative distance between the fixed adjustment element 13 and the position-variable adjustment element 14 and / or sensors 38 which are used when the position of the position variable setting element 14 monitor the setting of the desired position.

The operating parameters determined by sensors provide information about the operating state of the eccentric screw pump. The operating parameters are controlled by the controller 32 (compare Figure 2 ) compared with defined operating parameters, which are stored, for example, in a map or in a table in the controller 32. If there is no deviation between the actual operating parameters and the target operating parameters, the system does not react. Instead, the actual operating parameters are measured again after a time interval Δt1 and subjected to a comparison, so that the operating state of the eccentric screw pump or the stator-rotor system 10 is regularly monitored or checked.

If, on the other hand, there is a discrepancy between the actual operating parameters and the target operating parameters, the controller 32 uses a stored map or a stored table the necessary adjustment of the adjustment mechanism 12 and controls it accordingly. After the adjustment mechanism 12 has been automatically adjusted, the physical operating parameters of the eccentric screw pump or of the stator-rotor system 10 are measured again after a further time interval Δt2, and from this it is again determined whether the optimum operating state has been reached or is maintained. If the measured operating parameters do not correspond to the desired target operating parameters, the control 32 calculates an adjustment path again and the adjustment mechanism 12 is adjusted accordingly. In particular, an incremental setting is carried out using a control algorithm, as described below in connection with Figure 4 is described.

Even if the desired optimum operating state of the eccentric screw pump has been achieved by the adjustment, permanent monitoring is carried out by regular determination of the operating parameters at defined time intervals Δt3 and, if necessary, readjustment of the adjustment mechanism in order to optimize the deformation of the elastomer and thus the optimal operating state of the eccentric screw pump during operation to achieve.

Figure 4 represents the setting of an ideal operating point as a function of an adjustment path n of the adjustment mechanism. A specific speed Q of an eccentric screw pump is assigned. In particular, with a 100% volumetric efficiency, the volume flow Q would be exactly the volume that is conveyed by the individual conveying elements (conveying chambers) according to the speed from the suction side to the pressure side of the eccentric screw pump.

The optimal setting of an ideal operating point iBP of the eccentric screw pump now takes place as follows: If one considers the volume flow Q at a constant speed over a certain adjustment path n of the adjustment mechanism, it can be seen that the volume flow Q is almost constant over a longer adjustment path n. The required torque (in the diagram of the Figure 4 not shown), however, is not constant. If the preload is released by adjusting and / or repositioning the adjusting elements of the adjustment mechanism accordingly, the torque drops due to the lower friction losses due to the lower preload. In a generally large adjustment range in which there is at least largely no change in the volume flow Q If there is no or only a small backflow, the efficiency of the eccentric screw pump increases. The efficiency of the eccentric screw pump only drops when an operating point is reached in which backflow increasingly occurs. The point of highest efficiency represents the ideal operating point iBP and can be descriptively described as follows: The ideal operating point iBP of the eccentric screw pump lies precisely in the range of the adjustment path n of the adjustment mechanism, in which there is just enough preload between the rotor and stator that it is there is no or largely no backflow. The ideal operating point iBP is the point at which just as much preload is generated in the rotor-stator system as is necessary to generate the necessary back pressure without backflow of the medium.

1. 1. Erfassen von Betriebsparametern der Exzenterschneckenpumpe, beispielsweise Druck, Drehzahl, Drehmoment (Motorstrom), gegebenenfalls Erfassen des Volumenstroms Q, wobei die Messung beispielsweise mittels eines Volumenstrommessers, einer Messblende oder Ähnlichem erfolgt
2. 2. Einstellung des Rotor- Stator- Systems über den Verstellmechanismus: Zuerst fährt die Verstellung zu. Der Gummi des Elastomerteils wird verpresst, so dass die Rückströmung = 0 beziehungsweise weitgehend 0 ist. Insbesondere sinkt bei zunehmender Verpressung der Volumenstrom Q, da das Kammervolumen der Pumpkammern der Exzenterschneckenpumpe immer kleiner wird.
3. 3. wenn sichergestellt ist, dass man sich im Bereich ausreichender Verpressung befindet, wird die Verstellung wieder aufgefahren. Dabei bleibt der Volumenstrom Q anfangs bis zu einem bestimmten Punkt konstant. An diesem Punkt bricht der Volumenstrom Q ein, da die Rückströmung im Stator-Rotor-System zunimmt. Der ideale Betriebspunkt iBP befindet sich kurz vor diesem Einbruchspunkt. Der Bereich ausreichender Verpressung kann beispielsweise anhand der Messwerte für den Volumenstrom Q ermittelt werden. Beim Verschließen des Verstellmechanismus steigt der Volumenstrom Q an. Wenn sich dieser nicht mehr ändert beziehungsweise wenn der Volumenstrom Q leicht fällt, ist das Maximum überschritten.
4. 4. Die Einstellung nach Punkt 3 wird in bestimmten Zeitabständen eigenständig innerhalb des Rotor- Stator- Systems durchgeführt, sodass eine aktive Einstellung beziehungsweise Anpassung auf variierende Betriebsbedingungen der Pumpe gewährleistet ist.

This mode of operation is used for the new control algorithm, in particular an incremental approximation to the ideal operating state iBP. According to one embodiment of the invention, the control algorithm uses the following measurement principle:

1. 1. Detection of operating parameters of the eccentric screw pump, for example pressure, speed, torque (motor current), optionally detection of the volume flow Q, the measurement being carried out, for example, using a volume flow meter, an orifice plate or the like
2. 2. Adjustment of the rotor-stator system via the adjustment mechanism: First the adjustment closes. The rubber of the elastomer part is pressed so that the backflow = 0 or largely 0. In particular, the volume flow Q decreases with increasing compression, since the chamber volume of the pumping chambers of the eccentric screw pump becomes ever smaller.
3. 3. If it is ensured that you are in the area of sufficient pressing, the adjustment is started again. The volume flow Q initially remains constant up to a certain point. At this point, the volume flow Q drops because the backflow in the stator-rotor system increases. The ideal operating point iBP is just before this break-in point. The area of sufficient compression can be determined, for example, using the Measured values for the volume flow Q are determined. When the adjustment mechanism is closed, the volume flow Q increases. If this no longer changes or if the volume flow Q falls slightly, the maximum is exceeded.
4. 4. The setting according to point 3 is carried out independently at certain intervals within the rotor-stator system, so that an active setting or adaptation to varying operating conditions of the pump is guaranteed.

The invention has been described with reference to a preferred embodiment. However, it is conceivable for a person skilled in the art that modifications or changes of the invention can be made without leaving the scope of the following claims.

Reference list

1

Stator-rotor system

3rd

stator

4th

Elastomer part

5

Stator jacket

8th

free end

10th

Stator-rotor system

12th

Adjustment mechanism

13

first fixed setting element

14

second position variable setting element

23

flange

24th

Actuator

30th

Control system

32

control

35

sensor

36

first sensor

37

second sensor

38

third sensor

Δt

Time interval

iBP

Ideal operating point

n

Adjustment path

Q

Volume flow

X

Longitudinal axis

Claims (15)

1. An eccentric screw pump with a stator-rotor system (10), comprising a rotor with a rotor screw and a stator (3) with an internal thread, the stator (3) comprising a support element (5) and an elastomer part (4), wherein the support element (5) surrounds the elastomer part (4) at least in sections around the whole circumference, wherein the free outer end regions of the elastomer part (4) project beyond the support element (5) and are not surrounded by the latter, wherein the stator-rotor system (10) comprises an adjusting mechanism (12) for adjusting the stator (3), the adjusting mechanism (12) comprises a position-variable adjustment element (13) and a stationary adjustment element (14), wherein the adjusting mechanism (12) is coupled via a control (32) to at least one sensor (35) for the determination of actual operating parameters of the stator-rotor system (10) and/or of the eccentric screw pump, wherein activation of the adjusting mechanism (12) can be carried out by the control (32) taking account of the actual operating parameters determined by means of at least one sensor (35), wherein the two adjustment elements (13, 14) of the adjusting mechanism (12) arranged on the stator-rotor system (10) are distance-variable relative to one another, wherein a mechanical coupling and/or connection is present between the adjustment elements (13, 14) of the adjusting mechanism (12) and the stator (3), so that a change in the cross-section and the length of the elastomer part (4) of the stator (3) can be brought about by a change in the relative distance between the two adjustment elements (13, 14), characterised in that the one first adjustment element (13) is arranged stationary on the support element (5) and the other second adjustment element (14) is arranged position-variable on the on the elastomer part (4), in particular on a free outer end region of the elastomer part (4).
2. The eccentric screw pump according to claim 1, wherein the second position-variable adjustment element (14) can be repositioned by means of an actuator activated by the control (32) in order to change the distance relative to the first stationary adjustment element (13).
3. The eccentric screw pump according to claim 1 or 2, wherein at least one first sensor (36) is arranged on the eccentric screw pump and/or wherein at least one second sensor (37) is arranged on the elastomer part (4) of the stator (3) and/or wherein at least one third sensor (38) is arranged on the adjusting mechanism (12).
4. The eccentric screw pump according to claim 3, wherein the first sensor (36) is designed for the measurement of the pressure, the speed, the temperature and/or the volume flow of the eccentric screw pump and/or wherein the second sensor (37) is designed for the measurement of the pre-tensioning and/or of reaction forces of the elastomer material of the elastomer part (4) and/or wherein the third sensor (38) is designed for the measurement of the position of the second position-variable adjustment element (14) and/or for the measurement of the distance between the first stationary adjustment element (13) and the second position-variable adjustment element (14).
5. A method for adapting the operating status of an eccentric screw pump with a stator-rotor system (10) according to any one of claims 1 to 4, the stator-rotor system (10) comprising a rotor, a stator (3) and an adjusting mechanism (12) for adjusting the stator (3), the stator (3) comprising an elastomer part (4) and a support element (5), the method comprising the following process steps:

   a. Retrieval of an actual operating status of the eccentric screw pump by means of a sensor-based determination of at least one physical actual operating parameter relating to the eccentric screw pump and/or a sensor-based determination of at least one physical actual operating parameter relating to the elastomer part (4) and/or a sensor-based determination of at least one physical actual operating parameter relating to the adjusting mechanism (12);

   b. Comparison of the at least one actual operating parameter with known setpoint operating parameters;

   c. when a deviation is determined between the measured actual operating parameters and the setpoint operating parameters, activation of the adjusting mechanism (12) takes place for adjusting the stator (3);

   d. wherein the adjustment of the new operating status is monitored by means of a check on at least one physical actual operating parameter.
6. The method according to claim 5, wherein a calculation of an adjustment path (n) of the adjusting mechanism (12) is carried out when a deviation is determined between the measured actual operating parameters and the setpoint operating parameters and wherein the adjusting mechanism (12) is correspondingly activated for the adjustment of an ideal operating point (iBP) of the stator (3) and the calculated adjustment path (n) is set.
7. The method according to claim 5, wherein the adaptation of the operating status when a deviation is determined between the measured actual operating parameters and the setpoint operating parameters takes place by an adjustment of an ideal operating point (iBP) by means of the an incremental approach.
8. The method according to claim 7, wherein the adjusting mechanism (12) is transferred into an at least for the most part closed position with an increased pre-tensioning in the stator-rotor system (10), wherein the ideal operating point (iBP), at which the eccentric screw pump exhibits its greatest efficiency, is then set by means of a controlled opening of the adjusting mechanism (12) .
9. The method according to any one of claims 5 to 8, wherein a renewed retrieval of the actual operating parameters of the eccentric screw pump and a comparison with the setpoint operating parameters takes place after a defined period of time (Δt2) following the adjustment of the adjusting mechanism (12).
10. The method according to claim 9, wherein in the case of a persisting deviation between the actual operating parameters and the setpoint operating parameters, a renewed activation of the adjusting mechanism (12) takes place.
11. The method according to claim 9, wherein in the case of a sufficient reduction of the deviation between the actual operating parameters and the setpoint operating parameters, the adjusted operating status of the eccentric screw pump is again checked after a defined period of time (Δt3).
12. The method according to any one of claims 5 to 9, wherein in the absence of a deviation between the actual operating parameters and the setpoint operating parameters, a renewed retrieval of the actual operating parameters of the eccentric screw pump and a comparison with the setpoint operating parameters takes place after a defined period of time (Δt1).
13. The method according to any one of claims 5 to 12, wherein the pressure, the speed, the temperature and/or the volume flow of the eccentric screw pump is determined by means of sensors and/or wherein the pretensioning between rotor and stator (3) is determined by means of sensors and/or wherein reaction forces of the elastomer material of the elastomer part (4) are determined by means of sensors and/or wherein the position of at least one adjustment element (13, 14) of the adjusting mechanism (12) is determined by means of sensors and/or wherein the distance between the adjustment elements (13, 14) of the adjusting mechanism (12) is measured by means of sensors.
14. The method according to any one of claims 5 to 13, wherein the adjustment of the adjusting mechanism (12) takes place by increasing or reducing the distance between the two adjustment elements (13, 14) of the adjusting mechanism (12), wherein a change in the cross-section and the length of the coupled elastomer part (4) of the stator-rotor system (10) takes place through the change in distance between the two adjustment elements (13, 14) .
15. The method according to any one of claims 5 to 14, wherein the ascertained deviation triggers an activation of the adjusting mechanism (12) only when the ascertained deviation lies outside a specified tolerance range.

Images