DE102020111386A1 - Condition detection on eccentric screw pumps - Google Patents

Abstract

Eccentric screw pump, with- a pump housing with a pump inlet opening and a pump outlet opening, - a stator arranged in the pump housing- a rotor arranged in the stator- a drive unit comprising a drive motor and a drive shaft which connects the drive motor to the rotor to transmit a torque, - the rotor being guided for a rotating movement around a rotating axis in the stator, - a status sensor for detecting a status variable of the eccentric screw pump, characterized in that the status sensor- is arranged on the rotor or the drive shaft or- with the rotor or the Drive shaft is connected by means of a signal line and is arranged at a distance from the rotor or the drive shaft, for detecting a state variable on the rotor or on the drive shaft.

Description

The invention relates to an eccentric screw pump, with a pump housing with a pump inlet opening and a pump outlet opening, a stator arranged in the pump housing, a rotor of a drive unit arranged in the stator, comprising a drive motor and a drive shaft which connects the drive motor to the rotor for transmitting a torque, wherein the rotor is guided for a rotating movement around a rotating axis in the stator and a state sensor for detecting a state variable of the eccentric screw pump ..

Eccentric screw pumps are used to convey various media in a variety of applications. Eccentric screw pumps work on the principle of a volume displacement pump and for this purpose have a rotor which is driven in a rotation around its own rotor longitudinal axis in a stator, this rotor longitudinal axis in turn being rotated around a spaced apart, usually parallel, stator longitudinal axis, so that a Rotation of the rotor about the longitudinal axis of the stator and a rotation of the rotor about the longitudinal axis of the rotor as an eccentric rotation results in a superimposed movement of the rotor in the stator. Eccentric screw pumps can be used for a defined and plannable volume delivery by executing a certain number of revolutions which are proportional to the desired delivery volume. Eccentric screw pumps are often used in plant construction and are often used to supply a liquid loaded with foreign bodies. Particularly in the field of application in plant construction, but also in general, a failure of the eccentric screw pump is often synonymous with a longer downtime of the entire plant, which is associated with considerable disadvantages for the user.

A failure of an eccentric screw pump can be traced back to many causes. A frequent cause of failure is excessive wear on the stator, which in many types of eccentric screw pumps is made as a jacket construction from a rubber material or other elastomer, and in which there is a rotor made of metal, so that the wear that occurs between the rotor and stator is often essentially Affects stator side. The wobbling form of movement caused by the eccentric movement, however, also requires a corresponding mounting and, on the drive side, a corresponding torque transmission via a wobble shaft, which is often designed with two universal joints. In many designs of eccentric screw pumps, these cardan joints are also located in the inlet area of the stator and are therefore washed around by the conveyed medium, so that the load on these cardan joints and any leaks in the sealing of the cardan joints can also lead to joint wear or damage to bearings, which also affects the Failure of the eccentric screw pump can result.

Various solutions have been proposed to address these problems. For example, in eccentric screw pumps with low eccentricity, the wobble shaft is designed as a flexural torsion bar, which means that the two cardan joints in the drive train can be dispensed with and a cause of wear and failure can be avoided. However, this design is not suitable for pumps with a high throughput volume, because larger eccentricities are advantageous here and is therefore limited to smaller pump designs.

the end EP 2 944 819 B1 an eccentric screw pump type is previously known, which enables a greatly reduced repair time for replacing a rotor or stator of the eccentric screw pump. This is achieved through a specific stator flange design that enables the stator and the rotor arranged therein to be swiveled out without further pipelines connected to the eccentric screw pump having to be dismantled or other dismantling steps being necessary. The removal of the rotor from the wobble shaft, which is necessary for dismantling the rotor, can take place through a cavity in the rotor itself, so that access to the inlet chamber for dismantling a flange located there is also not necessary. With this maintenance-friendly eccentric screw pump construction, a considerable advantage is achieved in the case of maintenance. However, it is also desirable to predict the need for maintenance in order to be able to better plan such maintenance processes in regular plant operation.

For this purpose, different approaches have been pursued for a long time in order to identify an operating state that requires maintenance on eccentric screw pumps.

So it's over DE 100 63 953 A1 the monitoring of certain operating parameters of an eccentric screw pump is provided in that in the area of the joints or the bearing or in the area of the rotor or stator, pressure transducers, temperature sensors and vibration sensors are arranged. This measuring principle follows an approach that is used for other types of pumps, namely, for example JP 60-150491 A or DE 19 649 766 A already known principle of condition monitoring Evaluation of temperature or vibration values to obtain a statement about the wear condition of the pump. However, this approach is based on the fact that, due to the specific vibration state caused by the eccentric movement in eccentric screw pumps, an arrangement of several different sensors is provided in order to be able to detect with sufficient reliability an operating state that indicates wear from the normal operating state of the eccentric screw pump. With this approach, however, this leads to a disadvantageous arrangement of many different sensors in order to achieve a detection of the state of wear. In addition to the disadvantage that this makes assembly and disassembly of the eccentric screw pump considerably more difficult, and the costs of the eccentric screw pump increase, it has also been shown that even with this effort of several different sensors, a state of wear that is actually required for maintenance cannot be reliably detected, or only then can be recognized when significant damage has occurred. In particular, it is not possible to reliably preventively detect operating states that lead to increased wear.

the end DE 10 2005 019 063 B3 It is known to place a single vibration sensor on the outside of the eccentric screw pump and to evaluate its measurement results in order to draw conclusions about certain operating conditions or wear conditions. This counteracts the disadvantage of more difficult dismantling and increased costs due to the large number of sensors, but even with this prior art no reliable detection of wear conditions and operating conditions that lead to increased wear can be achieved.

the end DE 10 2018 113 347 A1 a new, more recent approach is already known in which an operating parameter in the form of the operating pressure or the torque of the pump is to be monitored on an eccentric screw pump on the basis of a pressure detection in the output of the eccentric screw pump. With this monitoring of the operating pressure / torque, a statement about these specific operating parameters should be made by means of a signal evaluation by means of Fourier transformation. In principle, this sensor arrangement in the pump outlet also makes it easier to assemble and disassemble than with the previously known solutions. However, the arrangement of the sensor has the disadvantage that a statement about the operating pressure of the pump, and indirectly derived from this, a statement about the torque should be made by means of a specific evaluation method and by comparison to calibrated comparison values, which to a considerable extent depends on the pumped medium and influences depends in the pipe network at the pump outlet. Conditions of wear and tear, in particular those that make maintenance necessary, or make this necessary at a predictable point in time in the future, cannot be reliably detected with this measured value acquisition and evaluation.

The previous approaches aim in particular at detecting a condition that directly requires maintenance. In principle, however, according to the inventors' knowledge, it would also be advantageous if it were possible to control an eccentric screw pump in such a way that operating states that particularly cause wear are preventively avoided. To do this, however, it is necessary not only to record the state of wear, which already requires maintenance, but also operating states that lead to increased wear on the one hand and can be avoided by changing the control of the eccentric screw pump on the other, so that the wear effect is reduced . According to the inventors' knowledge, this can be represented, for example, in the start-up behavior of pumps, in that a low-wear run-up of the pump is achieved there with a certain increase in speed, which can vary depending on the medium being conveyed. Furthermore, dry running conditions can be avoided by recognizing the lack of conveyed medium in real time and then stopping the pump or operating it at a greatly reduced speed.

From the going back to the patent applicant WO 2018/130718 A1 In addition, an eccentric screw pump with a conical design of rotor and stator is previously known, which provides an axial adjustment option between rotor and stator and thereby enables adjustment of the gap between rotor and stator. With this eccentric screw pump design, the starting behavior and the stopping behavior of the pump can be designed by controlling the axial infeed by means of an axial infeed from rotor to stator, and if there were knowledge of the wear and operating conditions of the pump, such an axial adjustment between rotor and stator can be more wear-intensive Operating state, if it is recorded, can be avoided in very rapid control, quasi in real time, specifically in the form of a control behavior or a control loop.

There is therefore a need for status monitoring of eccentric screw pumps, with which the disadvantages of the previously known modes of recording operating parameters of the eccentric screw pump are overcome and a more spontaneous and precise control of a Eccentric screw pump allowed to avoid wear and tear.

This object is achieved according to the invention with an eccentric screw pump of the type described above, in which the condition sensor is arranged on the rotor or the drive shaft or is connected to the rotor or the drive shaft by means of a signal line and is arranged at a distance from the rotor or the drive shaft for Detection of a state variable on the rotor or on the drive shaft.

According to the invention, a state variable is detected directly on the rotor or on the drive shaft. A state variable is to be understood here as a physical variable that is detected by means of a sensor device. This physical variable can be, for example, a temperature, a fluid pressure, a strain, a material tension, an alignment with respect to the direction of gravity, a speed according to absolute height and / or direction, or an acceleration according to absolute height and / or direction. According to the invention, this state variable is detected either by a state sensor which, according to a first alternative, is arranged on the rotor or the drive shaft. In this first alternative, the state sensor is therefore attached directly to the rotor or the drive shaft. The condition sensor can for example be fastened to the outer surface of the rotor or drive shaft, embedded in it, or arranged and fastened in an inner cavity of the rotor or the drive shaft, in particular in such a way that, starting from a cavity of a formed rotor or a hollow shaft The condition sensor is arranged as the drive shaft on an inner surface of this cavity or, starting from this cavity, is arranged in a channel which extends to the outer surface of the rotor or drive shaft and can optionally also penetrate this outer surface.

As an alternative to this, the state variable can, according to the invention, take place by means of a state sensor which is connected to the rotor or the drive shaft by means of a signal line and is itself spaced apart from the rotor and drive shaft. In this alternative case, the condition sensor is arranged at a distance from the rotor or drive shaft and is connected to the rotor or drive shaft by means of a signal line. In this alternative, an objectively designed signal line, i.e. no data transmission by radio waves or the like, is designed to convey a physical state variable via the signal line from a detection point on the rotor or on the drive shaft to the state sensor. For example, by means of a hollow line, such as a channel, a hose line, a pipe, a bore or the like, a pressure that is detected directly on the surface of the rotor or drive shaft can be diverted away from the detection location and detected elsewhere by the condition sensor. The signal line extends from the condition sensor to an end point that is arranged directly on the rotor or on the drive shaft, as explained above for the condition sensor arranged directly on the rotor or on the drive shaft.

By detecting the state variable on the rotor or on the drive shaft by means of the aforementioned arrangement of the state sensor or the signal line, a direct measured variable is recorded on the eccentric screw pump, which enables a direct conclusion to be drawn about a measured value relevant to the operating state of the eccentric screw pump. This direct detection makes it possible, on the one hand, to directly record physical quantities that are directly related to the rotation of the rotor or the drive shaft, for example pressure ratios, accelerations or vibration values, such as an amplitude or a frequency of the pressure or an acceleration caused by the rotation capture in real time. Furthermore, through this detection directly on the rotor or on the drive shaft, a temperature and its possible rise can also be detected in real time at a position at which a temperature peak typically occurs within the entire eccentric screw pump.

In the case of vibration measurements by means of a sensor arranged, for example, on the outer wall of the housing, the transport and propagation of the vibration waves from the source to the sensor must always be taken into account when evaluating the vibration signal. Here, material and structural dynamic properties, such as the rigidity of the overall structure and the resulting natural frequencies, play a decisive role. Furthermore, the damping properties of the conveyed medium and of the stator are a decisive disadvantage here. Due to the many influencing factors, a complex structural analysis of the system and a modal analysis of the measurement signal are often necessary. In this way, signal components can be extracted from the overall vibration spectrum that have been adjusted for some influencing factors, but due to the intensive signal processing there is a risk that systematic signal errors will flow into the evaluated signal or that certain status signals will be systematically filtered out of the signal.

In the case of the direct and immediate measurement according to the invention on or in the component that is decisive for the monitoring, that is to say the rotor or the wobble shaft, the evaluation takes place significantly simpler and at the same time and therefore more reliable, since the influences described above are significantly reduced and simpler methods such as a bandpass filter can be used.

Due to the arrangement of the condition sensor on the rotor or the drive shaft, the condition sensor rotates with the rotor or the drive shaft and can thus record a 360 ° profile, whereby a cross-sectional measurement of the condition is achieved. The informative value of such a measurement is much better and more precise than a measurement with a condition sensor arranged in a stationary manner on the eccentric screw pump.

The invention is based, inter alia, on the knowledge that an indirect acquisition of physical quantities and a calculation derived therefrom of critical operating parameters that can be derived therefrom on the one hand has the disadvantage that monitoring in real time due to the necessary comparative calculations, the necessary calculation steps per se and the necessity To compare integral time periods in this case is not reliable and sufficiently effective it enables an operating state that would lead to increased wear to be recognized and avoided by appropriate control measures. On the other hand, it is based on the knowledge that the arrangement of the state sensor on the rotor or on the drive shaft, or the derivation of the physical measured variable from the rotor or the drive shaft via a signal line, enables the state variable to be recorded at that location that typically makes the most direct change in state detectable with the greatest amount of change in state and a low dependence on conveying parameters such as temperature or viscosity of the conveyed medium.

According to the invention, therefore, it is not necessary to calculate back with imprecise assumptions from a state variable detected in a damped manner at another location to the actual change in the state variable at the critical location. For example, when the temperature or the pressure on the rotor or the drive shaft is detected, dry running can be detected immediately at the beginning of the dry running and the wear effects that follow from this can be avoided immediately by appropriate control. Overloads of bearings, which lead to increased wear of the bearings, can also be detected by a characteristic vibration behavior of the rotor or the drive shaft at the moment in which they occur for the first time and accordingly quickly by a corresponding reduction in power or speed or other control variable can be effectively avoided before wear and tear occurs as a result. Finally, real-time detection of the state variable on the rotor or the drive shaft is also suitable for controlling control variables of a conically designed rotor-stator arrangement in such a way that predetermined operating states of the eccentric screw pump can be approached in a targeted manner through axial adjustment between rotor and stator or through adjustment of the eccentricity predetermined operating state curves of the eccentric screw pump can be followed in a closed control loop.

According to a first preferred embodiment it is provided that the state sensor is arranged within the rotor or within the drive shaft or the signal line ends within the rotor or within the drive shaft. According to this preferred embodiment, the state variable is detected within the rotor or the drive shaft. This enables, on the one hand, a direct detection of the state variable on the eccentrically rotating component and, on the other hand, an arrangement of the state sensor protected from the influence of the conveyed medium and a possibly necessary sensor line or energy supply of the sensor or the signal line. For this purpose, the rotor or the drive shaft can be designed with an inner cavity, for example designed as a roll rotor or as a hollow shaft, and the condition sensor or the end of the signal line can then be arranged and fastened in this cavity.

It is even more preferred if the condition sensor is connected to an electronic evaluation unit in a wired manner via a sensor cable and the sensor cable or if the signal line runs within a section of the drive shaft and possibly within a section of the rotor. According to this embodiment, a sensor signal cable runs, which conducts the sensor signal electrically or as a light guide or in some other way from the state sensor attached to the drive shaft or rotor to an electronic evaluation unit, or the signal line runs through a state sensor arranged at a distance from the drive shaft or the rotor a section of the drive shaft and optionally within a section of the rotor.

This course enables a protected placement of the sensor signal cable or the signal line.

In particular, the sensor cable or the signal line can extend along the entire drive shaft and along the entire drive train to the end point or attachment point of the condition sensor on the rotor or on the drive shaft and in this case in sections through the drive shaft or the rotor or both walk through it. This enables an overall protected course of the sensor cable or the signal line and a routing of the sensor signal by means of corresponding transmission elements from the rotating shaft of the drive train to a stationary transmission unit.

It is particularly preferred if the drive shaft is a wobble shaft, which is connected at its end facing the drive motor with the drive motor for rotation about a drive axis, and at its end facing the rotor with the rotor for rotation around a rotor axis and the superimposed Rotation is connected to an eccentric axis spaced from the rotor axis.

According to this embodiment, the eccentric rotational movement of the rotor is transmitted by means of a wobble shaft as the drive shaft. This wobble shaft is rotatably mounted on the connection side to the drive motor and connected to the rotor at the connection point to the rotor and carries out the eccentric rotational movement of the rotor and the rotational movement of the rotor about its longitudinal axis at this point.

This wobble wave can basically be designed as a flexible rod in order to transmit a rotation around small eccentricities. However, it is particularly preferred if the wobble shaft has a wobble shaft center section, a first cardan joint and a second cardan joint, and the first cardan joint is inserted between the wobble shaft center section and the drive motor and the second cardan joint is inserted between the wobble shaft center section and the rotor. Such a configuration provides a wobble shaft that is also suitable for large eccentricities and high torques, in that two spaced cardan joints are provided. A universal joint is to be understood as any joint that can transmit a rotation with an angled shaft guide, for example also a pin joint or other designs.

In an embodiment of the wobble shaft with such cardan joints, it is particularly preferred if the sensor cable or the signal line is led into the first and / or the second cardan joint, or is passed through the first and optionally through the second cardan joint, or around the first and / or the second cardan joint. or the second universal joint is passed around. For a protected laying of the sensor cable and signal line, such introduction or passage through the first and / or the second universal joint is advantageous; in particular, this can also be combined with passage of the sensor cable or the signal line through the central section of the wobble wave. Often, wobble shafts with cardan joints are sealed from the pumped medium by means of a protective hose that is arranged around and seals each cardan joint, or a protective hose that extends over both cardan joints and the central section of the wobble shaft, sealed off from the pumped medium. In such a case, the sensor cable or the signal line can also be laid between this protective hose and the wobble shaft and is thus also laid so that it is protected from the pump medium. In particular, the sensor cable or the signal line can also be incorporated into such a protective tube or placed between two protective tubes arranged as a double sheath or the like in order to protect the sensor cable from mechanical stresses caused by the wobble wave.

It is particularly preferred if the first universal joint is enclosed by a first sealing sleeve and the second universal joint is enclosed by a second sealing sleeve or the first and second universal joint and the wobble shaft are enclosed by a sealing sleeve, and that in the first and / or the second sealing sleeve or a pressure sensor is arranged in the sealing sleeve, or a pressure line is guided into the first and / or the second sealing sleeve or in the sealing sleeve and a pressure sensor is in fluid connection with the pressure line to detect the pressure in the first and / or second sealing sleeve or in the sealing sleeve, and the pressure sensor is connected for signaling purposes to an evaluation device which is designed to detect the pressure within the first and / or second sealing sleeve or within the sealing sleeve by means of the pressure sensor, with the pressure sensor preferably being the Dr uck of a pressure line guided into the first and / or the second sealing sleeve or into the sealing envelope or pressure medium fed through the pressure line is detected.

According to this form of development, a pressure sensor is arranged within one of the sealing sleeves or the sealing sleeve or a pressure sensor in each of the sealing sleeves, or a pressure line is used as the signal line, which is correspondingly inserted into a first or second sealing sleeve around the first or second universal joint or into a joint Sealing sleeve of the first or second universal joint is inserted and a pressure within these sealing sleeves or the sealing sleeve is detected. In particular, a first pressure sensor can also be provided here, which is located within the first Sealing sleeve is arranged or is connected to a pressure line which opens into the first sealing sleeve and a second pressure sensor which is arranged inside the second sealing sleeve or is connected to a pressure line which opens into the second sealing sleeve. With the construction of a pressure detection within the sealing sleeves or the sealing sleeve, a pressure drop or pressure increase within this sealing sleeve, which indicates a leak in the sealing sleeve / sealing sleeve, can be recorded reliably and immediately. Such a leak, which will ultimately result in the pumped medium accessing the cardan joints in rapid succession, is an event that will immediately result in high wear. The detection of this leakage is therefore important in order to avoid such undesirable and high wear. In this case, the invention enables the sealing sleeve to be sealed or replaced before such wear has occurred, which then necessitates an expensive repair with replacement of one or both cardan joints and possibly further bearing elements. It is particularly advantageous if a pressure medium is fed into the sealing sleeve or sealing sleeve via a pressure line. If a pressure line is provided as a signal line, this can also be done via this signal line. This makes it possible to build up and maintain a pressure within the sealing sleeve. On the one hand, this makes it possible to generate a distance between the sealing sleeve or sealing sleeve and the cardan joints, as a result of which mechanical damage to the sealing sleeve or sealing sleeve by the cardan joint can be avoided. On the other hand, a defined pressure can be generated within the sealing sleeve or sealing envelope, so that a pressure drop can be reliably determined and differentiated from pressure influences that are generated by the conveyed medium itself.

According to a further embodiment it is provided that the status sensor is connected to an electronic evaluation unit for signal transmission and the electronic evaluation unit is designed to determine a deviation of an ACTUAL status detected by the status sensor based on the status sensor data from a predetermined target status Compare the deviation with a predetermined permissible deviation and then, if the determined deviation exceeds the permissible deviation, output an alarm signal.

It can be provided in particular if the electronic evaluation unit is designed to receive a condition sensor signal as the actual condition, to compare the condition sensor signal with a stored normal condition sensor signal as the TARGET condition and to calculate the determined deviation as the difference between the condition sensor signal and the normal condition sensor signal, as predetermined permissible deviation to use a predetermined permissible deviation value, and to output a value alarm signal as an alarm signal. According to these forms of advanced training, the detection of a sensor signal from the condition sensor, which signals an unfavorable operating condition, that is to say an operating condition that causes or will cause increased wear, is based on a comparison of target and actual data. The target data are stored in electronic form, for example as a data value, data value curve, algorithmic description of a data value curve or as a comparison table with several target values for different operating states of the eccentric screw pump. On the one hand, the setpoint data can be predetermined and stored in advance, that is to say given to the eccentric screw pump ex works, so that they contain characteristic values that are characteristic and constant for the type of eccentric screw pump.

The setpoint data can be defined, for example, by the pump's own structural properties such as the eccentricity, constant state values, and load values defined by the drive train. The setpoint data can, however, also be determined as a reference or calibration value when pumping a specific medium, in order then to be stored. This reference or calibration value can be determined, for example, by the user when pumping a certain medium for the first time or when the pump is first started up in a certain installation situation and is then used for comparison during further monitoring, i.e. during subsequent measurements of an actual value, so that critical changes are made the original reference or calibration value can be recognized immediately. In principle, any deviation of the actual data from the target data can be output as an alarm. However, it is often practicable to define a tolerance range within which the actual value may fluctuate around the setpoint value without this defining a critical operating state of the eccentric eccentric screw pump.

According to a further preferred embodiment, it is provided that the electronic evaluation unit is designed to receive state sensor signals, to determine a state change value as the ACTUAL state from at least two chronologically consecutive state sensor signals, and to compare the state change value with a stored normal state change value as the target state, which to calculate the determined deviation as the difference between the state change value and the normal state change value, as a predetermined permissible deviation use a predetermined allowable deviation change value, and to output a change alarm signal as an alarm signal.

It is even further preferred if the electronic evaluation unit is designed to receive condition sensor signals, to determine a rate of change of condition as the actual condition from at least three consecutive condition sensor signals, and to compare the rate of change of condition with a stored rate of change of normal condition as the target condition, the determined deviation to calculate as the difference of the rate of change of state from the normal rate of change of state, to use a predetermined allowable speed deviation as the predetermined allowable deviation, and to output a rate of change alarm signal as an alarm signal.

According to these forms of advanced training, on the one hand a status change signal is determined that characterizes the changes of two chronologically successive actual values. This status change signal can be understood as the first time derivative of the status signal and often provides an assessment basis for a critical operating status that has occurred or is imminent, better than the absolute value of a status signal. Likewise, a rate of change of state can be determined from successive state sensor signals in which the second time derivative of the state signal is to be understood. By calculating and using this state change value or the state change speed, on the one hand the speed and on the other hand the acceleration with which the state signal changes are determined. These two values are better suited for many physical variables that are recorded on the rotor or on the drive shaft in order to record a critical operating condition of the progressing cavity pump that has occurred or is emerging than the condition signal alone. When the status signal is only detected, it is often only possible to define a limit value that is perceived as critical. However, in order to allow normal operation without interruption and without alarms, this limit value must actually be defined close to the critical limit. In contrast, when detecting the rate of change of the status signal or the speed at which this rate of change changes, it can already be recognized in a range that is still permissible for the absolute value of the status signal whether the eccentric screw pump is moving towards a critical operating condition. For example, a large increase in pressure in the eccentric screw pump or a very rapid change in the rise or fall in pressure can indicate a closed state on the pressure side of the pump or a closed state on the suction side of the pump and can be detected at an early stage in order to activate the eccentric screw pump to accomplish. Likewise, a large rise in temperature or a large rate of change in the rise in temperature, that is to say an accelerating rise in temperature, can already signal dry running when the absolute temperature has not yet reached a critical state value. Here, too, the direct status detection on the rotor or the drive shaft and the difference consideration made possible by this after the first time derivative or the second time derivative enables a real-time reaction of the control of the eccentric screw pump to be achieved by monitoring the status, which prevents damage and wear can.

Overall, it is further preferred if the electronic evaluation unit is designed to compare a plurality of chronologically consecutive ACTUAL states with a plurality of chronologically consecutive TARGET states, and to calculate a deviation characteristic value from the comparison as the determined deviation, as predetermined permissible Deviation to use a predetermined permissible deviation parameter. According to this embodiment, a predetermined deviation is used for the determined changes in the state variables or changes in the rate of change of the state variables in order to enable operation within a tolerance window that is considered to be uncritical and to trigger a corresponding alarm when this tolerance window is exceeded.

It is further preferred that the eccentric screw pump has a rotor with a conical envelope and a conically tapering stator interior and that the rotor and the stator can be adjusted relative to one another by means of an axial actuator, the electronic evaluation unit is connected and designed with the axial actuator for signal transmission in order to control the actuating drive in order to carry out an axial adjustment between the rotor and stator, during the axial adjustment process, to detect several successive status sensor signals of the status sensor. According to this embodiment, an adjustability of the radial gap between rotor and stator is made possible by means of a conically tapering rotor and stator, in that an axial adjustment movement takes place between rotor and stator. For this purpose, the stator can be designed to be stationary and the rotor can be axially adjustable. The axial adjustment device can in particular be designed in such a way that the rotor can be axially adjusted during operation, for example by including the rotor The wobble shaft and drive motor can be adjusted axially. For this purpose, a controllable actuator can be used, for example, which can preferably set a predetermined axial position via a displacement sensor. The drive motor or other parts of the drive train can also be designed to be axially fixed and connected to the rotor by means of a torque-transmitting axial thrust connection. The axial adjustment movement of the rotor typically influences the status signal and can be used to achieve a change in the status signal. For this purpose, according to the invention, at least one status signal is recorded during the adjustment process, preferably several consecutive status signals. The axial adjustment movement can take place as a function of the status signals. This can be done by controlling the axial adjustment or a closed control loop in which the status signal is used as an input or reference variable and the axial adjustment movement is used as an output or control variable. The axial adjustment between rotor and stator allows a spontaneous correction of the operating status of the eccentric screw pump. It can be used to optimize the start-up behavior of the pump, for example to achieve a power-saving run-up with a larger gap and then to reduce the gap after the desired speed has been reached or during run-up. Furthermore, the axial adjustment can be carried out by monitoring a status signal such as the drive power, the torque or the temperature until there is a gap between the rotor and stator that is ideal for pump efficiency and wear.

It is even further preferred if the condition sensor is arranged on the drive shaft or the rotor and is also connected to a condition sensor data transmission module for wireless transmission of condition data to a data receiver outside the eccentric screw pump, the condition sensor and the condition sensor data transmission module having an energy converter for receiving electrical energy is connected, which is arranged on the rotor or on the drive shaft and which is designed to convert a kinetic or thermal energy acting on it into electrical energy. According to this embodiment, the status sensor is arranged as an autonomous module on the rotor or drive shaft and transmits the status data wirelessly to a receiver spaced therefrom. The energy required for status data acquisition and transmission is provided via an energy converter, which is also arranged on the rotor or the drive shaft and connected directly to the status sensor for energy transmission or designed as a common module with it. The energy converter can be designed, for example, in such a way that it generates electrical energy from the rotational movement, an acceleration or oscillation resulting therefrom, by induction. Other types of converters can also be used, for example thermal converters that generate electrical energy from a temperature of the pumped medium.

• - einem auf elektromagnetischem Induktionsprinzip beruhenden Wandler, der eine relative Rotationsbewegung des Rotors oder der Taumelwelle gegenüber einem Pumpengehäuse in eine elektrische Energie wandelt,
• - einem auf elektromagnetischem Induktionsprinzip beruhenden Wandler, der eine aus der Rotation des Rotors oder der Taumelwelle um eine Rotorachse und der Rotation des Rotors um eine Exzenterachse resultierende reziprozierende Beschleunigung des Rotors oder der Taumelwelle in eine elektrische Energie wandelt, oder
• - einem auf einem thermoelektrischen Prinzip beruhendem Wandler, der ein Temperaturgefälle in elektrische Energie wandelt, wobei der Wandler insbesondere in einem Bereich angeordnet ist, der einem Temperaturgefälle zwischen dem geförderten Medium und einem Pumpenbauteil wie dem Rotor, der Taumelwelle oder dem Stator ausgesetzt ist.

In particular, it is preferred if the energy converter is selected from:

• - a converter based on the electromagnetic induction principle, which converts a relative rotational movement of the rotor or the wobble shaft with respect to a pump housing into electrical energy,
• - A converter based on the electromagnetic induction principle, which converts a reciprocal acceleration of the rotor or the wobble shaft resulting from the rotation of the rotor or the wobble shaft around a rotor axis and the rotation of the rotor around an eccentric axis into electrical energy, or
• - A converter based on a thermoelectric principle that converts a temperature gradient into electrical energy, the converter being arranged in particular in an area that is exposed to a temperature gradient between the conveyed medium and a pump component such as the rotor, the wobble shaft or the stator.

It is also preferred if two state sensors are arranged on the rotor, which are arranged at two positions spaced apart from one another and the positions have a phase offset of the measured state variable, the phase offset preferably being due to an axial spacing of the state sensors that is greater or smaller than an integral multiple the pitch of the rotor, or is achieved by an angular distance between the two state sensors that is not equal to an integral multiple of 360 ° divided by the number of threads of the rotor. With this embodiment, a simultaneous, phase-shifted measurement of two state variables is achieved. A phase offset is to be understood here as a detection of the two state variables within a periodic curve, which takes place at two points of the periodic curve that are not spaced from one another by exactly an integral multiple of the wavelength of the periodic curve. If these two state variables are recorded by means of two state sensors on a three-flight eccentric screw rotor, this can be done in different positioning methods. For example, the phase offset can be achieved in that the two state sensors are not spaced apart from one another in the axial direction - that is, in one The cross-sectional plane of the rotor lie - but have an angular offset to one another in this cross-sectional plane that differs from the quotient 360 ° / n, where n corresponds to the number of threads of the rotor. Accordingly, a phase-shifted measurement could be carried out in a three-speed rotor if the state sensors are offset from one another by an angle that is not equal to 120 ° or 240 °, i.e. are offset from one another by 90 ° or 180 °, for example. With a two-turn rotor, the angular offset would have to be unequal to 180 ° in order to achieve a phase-shifted measurement, with a four-turn rotor unequal to 90 °, 180 ° and 270 °. It must be taken into account that in eccentric screw pumps, the principle of the number of threads on the stator is always one higher than the number of threads on the rotor.

A phase-shifted measurement can also be achieved if the status sensors have an angular offset that corresponds to the quotient 360 ° / n, in that the status sensors are axially spaced by a distance that is not a multiple of the pitch of the thread of the rotor. The division is to be understood as the axial distance between two adjacent thread peaks and corresponds to the pitch for a single thread and to the quotient of pitch / number of thread turns (n) for a multi-start thread. In particular, a phase offset can be set in that the state sensors are spaced apart from one another by an axial distance which corresponds to half the division, so that a phase offset of half a wavelength is achieved.

By measuring with a phase offset, a particularly favorable monitoring of certain signs of wear is achieved. Thus, by subtracting the sensor signals from the two state sensors, a measured variable adjusted for effects that occur in only one phase can be obtained, which allows a statement to be made about the effects of wear occurring locally in an angular range. In addition, by comparing sensor signals obtained offset in time by the phase offset, a relative statement on changes in state can be obtained.

Deviating from this or in addition, it is also advantageous in certain applications if two condition sensors are arranged on the rotor, which are arranged at two mutually spaced-apart in-phase positions, the phase equality preferably by an axial spacing of the condition sensors, which is a multiple corresponds to the pitch of the rotor, or by an angular distance between the two condition sensors by an angle that is an integral multiple of 360 ° divided by the number of thread turns. With this embodiment, a simultaneous, phase-synchronous measurement of two state variables is achieved. This measurement method allows a comparison of two status values recorded at the same time at different positions and can therefore enable direct conclusions to be drawn about locally caused changes in the operating status.

In particular, it can also be preferred to provide three or more status sensors, two of which are arranged out of phase with one another and two status sensors are arranged in phase in order to combine the advantages explained above and to obtain comprehensive information on the operating status.

It is also preferred if the state sensor is a temperature sensor, a pressure sensor, a vibration sensor, or an acceleration sensor.

In particular, an evaluation by means of a comparison with a previously stored and / or calibrated master curve can provide information about an equilibrium temperature that is being established. A detailed analysis of the course of the curve, taking into account the slope and curvature, allow additional evaluation options. For example, the relaxation time constant correlates with the dynamic properties of the stator's elastomer jacket. A comparison of the area integrals describes the damping performance during the running-in phase.

In principle, a pressure difference can be determined by a measurement using two or more pressure sensors axially spaced along the rotor axis, which can be used, for example, for a volume flow calculation.

By measuring the vibration generated in the rotor using an acceleration sensor or a vibration sensor, it is possible, for example, to monitor the natural frequencies of the rotor-stator system through the continuous excitation during pumping operation. By changing significant signal components, conclusions can be drawn about the material and structural properties of the rotor and thus, for example, the occurrence or spread of cracks or deformations of the stator can be recognized. It is also possible to detect the impact of more massive foreign bodies carried along in the conveying medium, such as stones or screws. When such an operating state is detected, the user of the pump can then be warned of damage caused by these foreign bodies and thus check his pumping process in order to prevent damage to the pump, or a signal derived directly from the state sensor signal can be used Control measure can be carried out, for example an emergency stop of the pump or a speed reduction.

• 1 eine längsgeschnittene Ansicht einer Exzenterschneckenpumpe gemäß der Erfindung,
• 2 eine längsgeschnittene Ansicht eines Ausschnitts einer ersten Ausführungsform der erfindungsgemäßen Exzenterschneckenpumpe,
• 3 eine Ansicht gemäß 2 einer zweiten Ausführungsform der Erfindung,
• 4a eine längsgeschnittene Teilansicht einer dritten Ausführungsform der Erfindung,
• 4b eine Ansicht gemäß 4a einer vierten Ausführungsform der Erfindung,
• 4c eine Ansicht gemäß 4a einer fünften Ausführungsform der Erfindung,
• 4d eine Ansicht gemäß 4a einer sechsten Ausführungsform der Erfindung,
• 4e eine Ansicht gemäß 4a einer siebten Ausführungsform der Erfindung,
• 4f eine Ansicht gemäß 4a einer achten Ausführungsform der Erfindung,
• 4g eine Ansicht gemäß 4a einer neunten Ausführungsform der Erfindung,
• 4h eine Ansicht gemäß 4a einer zehnten Ausführungsform der Erfindung,
• 4i eine Ansicht gemäß 4a einer elften Ausführungsform der Erfindung,
• 4j eine Ansicht gemäß 4a einer zwölften Ausführungsform der Erfindung,
• 4k eine Ansicht gemäß 4a einer dreizehnten Ausführungsform der Erfindung,
• 5a eine schematische Darstellung des an der Taumelwelle bzw. an dem Rotor stattfindenden Messvorgangs gemäß einer ersten Ausführungsform,
• 5b eine schematische Darstellung des an der Taumelwelle bzw. an dem Rotor stattfindenden Messvorgangs gemäß einer zweiten Ausführungsform,
• 5c eine schematische Darstellung des an der Taumelwelle bzw. an dem Rotor stattfindenden Messvorgangs gemäß einer dritten Ausführungsform,
• 6a eine schematische Darstellung des Verlaufs dreier charakteristischer Messwerte, die an der Taumelwelle oder dem Rotor aufgenommen werden, über die Betriebsdauer einer Exzenterschneckenpumpe,
• 6b einen typischen schematischen Verlauf von drei an dem Rotor aufgenommenen Temperaturen über die Zeit,
• 6c einen typischen schematischen Verlauf der Bewegung eines am Rotor befestigten Sensors in drei Richtungen über die Zeit bei einem normalen Betriebszustand,
• 6d einen typischen schematischen Verlauf der Bewegung eines am Rotor befestigten Sensors in drei Richtungen über die Zeit bei einem Betriebszustand einer Pumpe mit fortgeschrittenem Verschleiß.

Preferred embodiments of the invention are explained with reference to the accompanying figures. Show it:

• 1 a longitudinal sectional view of an eccentric screw pump according to the invention,
• 2 a longitudinal sectional view of a section of a first embodiment of the eccentric screw pump according to the invention,
• 3 a view according to 2 a second embodiment of the invention,
• 4a a longitudinal sectional partial view of a third embodiment of the invention,
• 4b a view according to 4a a fourth embodiment of the invention,
• 4c a view according to 4a a fifth embodiment of the invention,
• 4d a view according to 4a a sixth embodiment of the invention,
• 4e a view according to 4a a seventh embodiment of the invention,
• 4f a view according to 4a an eighth embodiment of the invention,
• 4g a view according to 4a a ninth embodiment of the invention,
• 4h a view according to 4a a tenth embodiment of the invention,
• 4i a view according to 4a an eleventh embodiment of the invention,
• 4y a view according to 4a a twelfth embodiment of the invention,
• 4k a view according to 4a a thirteenth embodiment of the invention,
• 5a a schematic representation of the measuring process taking place on the wobble shaft or on the rotor according to a first embodiment,
• 5b a schematic representation of the measuring process taking place on the wobble shaft or on the rotor according to a second embodiment,
• 5c a schematic representation of the measuring process taking place on the wobble shaft or on the rotor according to a third embodiment,
• 6a a schematic representation of the course of three characteristic measured values, which are recorded on the wobble shaft or the rotor, over the operating time of an eccentric screw pump,
• 6b a typical schematic curve of three temperatures recorded on the rotor over time,
• 6c a typical schematic course of the movement of a sensor attached to the rotor in three directions over time in a normal operating state,
• 6d a typical schematic course of the movement of a sensor attached to the rotor in three directions over time in an operating state of a pump with advanced wear.

In 1 the typical structure of an eccentric screw pump is shown. The pump has a stator 10 on, one of which extends along a longitudinal axis of the stator A. having extending cavity in the form of a spiral spiral flight with two flights. The stator 10 typically comprises a metal tube 11 or another stable shell construction that has an elastomer jacket 12th encloses, which forms a cavity with the screw geometry inside. In the stator cavity is a rotor 20th arranged along a longitudinal axis of the rotor B. extends, which is offset by the so-called "eccentricity" parallel to the longitudinal axis of the stator A. runs. Eccentric screw pumps can be designed with rotors and stators of different numbers of gears. Basically, the number of turns of the rotor is always one gear higher than the number of turns of the stator for the functional principle.

The stator interior and the rotor can taper in the axial direction in the pumping direction (not shown), so that this leads to an inlet opening 1 Pointing end of the rotor and the stator interior have a larger cross-sectional area than that to an outlet opening 2 pointing end. In the case of such tapering (typically equipped with a conical envelope or a conically tapering interior) rotor and stator, the rotor and the stator are then arranged to be axially displaceable with respect to one another (axial movement Ax). Axial infeed is then preferably possible during the rotational movement Ro of the rotor. In this way, on the one hand, wear-related play or insufficient pre-tensioning of the rotor in the stator can be compensated for by moving the rotor further into the stator. In addition, a start-up behavior of the pump can be optimized by the axial adjustment, for example by performing the axial adjustment as a function of the pumping behavior on the basis of the state variables. For example, it is possible to react to different viscosities of the pumped medium.

The rotor 20th is caused by a wobble wave 30th in rotation around its longitudinal axis of the rotor B. offset. The wobble wave 30th is here between the rotor and a drive input shaft, which is via a belt drive 41 from a drive motor 40 is driven, used and transmits a rotational movement of the drive motor 40 on the rotor 20th . The wobble wave 30th extends from a drive input end 30a rotating in an inlet housing 50 is mounted to a drive output end 30b connected to the rotor. At the drive output end 30b leads the wobble wave 30th a combined movement that is composed of a rotation around the longitudinal axis of the rotor B. and a rotation of the longitudinal axis of the rotor B. around the longitudinal axis of the stator A. . At this drive output end, the wobble shaft can be guided by means of an eccentric bearing implemented by two rotary bearings with eccentrically offset axes, or it can be unguided, so that the movement of the drive output end of the wobble shaft is defined by the guidance of the rotor in the stator.

The wobble wave 30th points at the drive input end 30a an entrance cardiac joint 31 on and at the drive output end an output cardan joint 32 . Between the two universal joints 31 , 32 a shaft section extends 33 that connects the two universal joints. The entrance cardiac joint 31 is with the drive input shaft and via the belt drive with the output shaft of the drive motor 40 tied together. The exit cardiac joint 32 is connected to the rotor.

The entire wobble wave 30th is in an inlet housing 50 arranged and is of a medium to be pumped, which through an inlet opening 51 into the inlet housing 50 flows in, washes around. This represents the suction side of the pump. The wobble shaft is therefore all in a protective cover 36 which extends over the cardiac entrance joint 31 , the shaft section 33 and the cardiac output joint 32 extends.

The rotor 20th and the stator 10 extend from an inlet end attached to the inlet housing 10a to one at an outlet end 20a attached outlet housing 60 . On the outlet housing 60 is an outlet port 61 arranged through which the pumped medium flows out of the pump and which represents the pressure side of the pump.

2 shows a section showing the wobble shaft with the drive input shaft attached to it and the rotor attached to it. In this embodiment there is a sensor 101 in a radial direction to the longitudinal axis of the rotor B. running bore 102 used in the rotor. The sensor can be, for example, a temperature sensor, an acceleration sensor or a pressure sensor. The rotor 20th furthermore has a longitudinal bore 21 which extends along and coaxial to the longitudinal axis of the rotor B. extends.

In the embodiment according to 2 is the sensor 101 by means of a sensor signal line 110 connected by the longitudinal bore 21 runs in the rotor, starting from there in a coaxial to the longitudinal bore 21 running flange bore 34 in the connection flange of the output cardan joint 31 flows out. From this longitudinal flange bore 34 the sensor signal line runs 103 by one extending in the radial direction to the longitudinal axis of the rotor B. extending bore in the connection flange of the output cardan joint 31 to a position outside the universal joint 31 . The signal line then runs outside the universal joint 31 , the shaft section 33 and the universal joint 32 , but within the protective cover 36 to the entrance end of the wobble wave 30th . At this input end, the signal line runs analogously to the output end through a radial hole in the shaft section-side connection flange of the input cardan joint to an axial hole in the drive input shaft-side connection flange of the cardan joint, from there into a coaxial longitudinal hole in the drive input shaft. The sensor signal line can then be routed to a sensor signal rotation transmission, which can be implemented, for example, in the form of several slip rings or the like, in order to lead the sensor signal from the rotating part of the eccentric screw pump to the outside into a stationary part of the eccentric screw pump.

3 shows a variant of the signal line routing. The figure shows a basically identical structure as 2 . In contrast to this, however, in this variant the signal line is guided exclusively through axial longitudinal bores in the connecting flange of the cardan output joint, the shaft section and the connecting flange of the cardan input joint, in order to open into the longitudinal bore in the drive shaft.

In this case, the signal line also runs through corresponding cross bores in the bolts of the two cardan joints. It should be understood that the dimensions of the channels in which the signal line runs are correspondingly large, so that the signal line remains free of shear and therefore damage even with the wobbling movement that occurs during operation and the kinking of the cardan joints.

Both at 2 as well as at 3 the drive input shaft can be attached to the input-side universal joint by means of a central bolt, which extends through partially or fully through the drive input shaft and is attached to the universal joint to axially tension a conical fit between the drive input shaft and the universal joint. Another difference can be seen in the fact that in the embodiment according to FIG 2 the signal line in the drive input shaft is guided in an axially extending longitudinal groove in the shaft (for example in the manner of a keyway) and is therefore to the side of this bolt, whereas in the embodiment according to FIG 3 a hollow bolt is provided which runs in the drive input shaft designed as a hollow shaft and the signal line runs within the inner cavity of this hollow bolt.

In the 4a-k different variants of the sensor arrangement on the rotor are shown. Basically, it should be understood that the sensors depicted in these figures can be pressure sensors, temperature sensors, acceleration sensors, vibration sensors, or other sensors. It should also be understood that the 4a-k depicted variants of the sensor arrangement can also be combined with one another, on the one hand in such a way that sensors of the same type can be arranged at different locations according to these variants or that sensors of the same type can be used at different locations according to these variants, or that in one of these variants location shown several sensors of different types can be arranged. Likewise, the signal transmission principles and the energy supply of the sensors, which in these variants according to 4a-k are shown, can be combined with each other.

4a shows an arrangement of the sensor 301 in the rotor, in which the sensor is inserted into the outer surface of the rotor. This sensor arrangement can, as previously based on the 2 and 3 shown, take place through a corresponding radially extending bore in the rotor and axially extending bore in the rotor, if the sensor is by means of a signal line 305 the sensor signal is to be transmitted and, if necessary, through a power line running parallel to it 306 should be supplied with energy.

It is generally advantageous about an arrangement of the sensor in the outer surface of the rotor that this position on the one hand enables circumferential signal acquisition, i.e. signal acquisition over an angle of rotation of 360 ° around the longitudinal axis of the rotor or the longitudinal axis of the stator and thus enables a type of cross-sectional acquisition of the signal. Another advantage of the arrangement of the sensor on the rotor, and especially when the sensor is arranged in the area of the outer surface of the rotor, is the possibility of using this sensor to record signals of a characteristic value on the stator and a characteristic value on the rotor as well as a characteristic value of the conveyed medium during operation. This signal acquisition can take place in particular during one revolution of the rotor over 360 °. This is made possible by the fact that in this sensor position on or near the surface of the rotor during operation of an eccentric screw pump, on the one hand, it comes into direct contact with the stator, and on the other hand, it comes into a distance from the stator during further rotation and thus comes into contact with the pumped medium whereby a detection of the stator and a detection of the medium is possible in each case periodically. In addition, the arrangement in the rotor itself also enables a measurement towards the rotor. This can in particular be a temperature measurement in which, depending on the angle of rotation of the rotor around the longitudinal axis of the rotor, the temperature of the stator is measured in certain angles, angular ranges or over the entire circumference in relation to the longitudinal axis of the stator and also the temperature of the conveyed medium. Furthermore, for example by designing the sensor with several sensors, the temperature of the rotor can also be detected by the sensor. Basically, it should be understood that the sensor can also be designed as a sensor unit and can detect several measuring functions of the same or different physical quantities.

In the 4a The sensor position shown can also be used for piezoelectric or capacitive vibration sensors in order to detect vibrations or accelerations of the rotor at this installation position of the sensor. These sensors can be single-axis or multi-axis measuring. Eddy current sensors can also be used at this position in order to measure the distance or position of the rotor.

4b shows schematically a with 4a matching positioning of the sensor 401 . In this installation variant, however, only the signal line is used 405 wired from the sensor to the receiving device. An energy converter is adjacent to the sensor to supply energy to the sensor 407 arranged, which converts temperatures or temperature gradients into electrical energy, as can be done, for example, with a pelletizing element. This energy converter takes advantage of the fact that the friction between the rotor and stator and the medium flowing through it causes temperatures that change with respect to the ambient temperature and consequently temperature gradients that enable an energy conversion that is sufficient to supply the sensor with energy.

4c shows another variant in which the position of the sensor 501 and the signal line 505 according to the sensor position 4a and the sensor is supplied with energy by means of an energy converter. The energy converter is based on the principle of induction, on the one hand in the inlet housing 50 corresponding magnets 508 , are arranged as fixed magnets or coil magnets and a coil is located in the area of the output cardan joint or at the inlet end of the rotor 507 in which a current flow is triggered by induction. The generator / dynamo acting in this way when the rotor rotates then generates the necessary electrical energy to supply the sensor via a short power line 506 .

In 4d a further variant of the energy supply is shown. This variant is a piezo transducer or an electrodynamic transducer 607 arranged in the rotor, which generates electrical energy from the vibration caused by the eccentric rotational movement of the rotor, and the sensor 601 herewith supplied. Again, the signal transmission takes place in a wired manner via a signal line 605

4e and 4f show a variant in which two sensors 701a , b respectively. 801a , b in the same angular position in relation to the longitudinal axis of the rotor B. but axially spaced from one another along the longitudinal axis of the rotor B. are arranged on the rotor. It is with 4f the axial distance between the two sensors 701a , b chosen so that both sensors are arranged in the area of a thread tip of the thread turn of the rotor, the axial distance thus corresponds to the pitch of the rotor thread, whereas at 4e the axial distance between the two sensors 801a , b is chosen so that one sensor is arranged in the area of a thread tip and the other sensor in the area of a thread groove, the axial distance here thus corresponds to half the pitch of the rotor thread. In both variants, the sensors are connected via a common power line 706 , 806 supplies and conducts their signals via separate signal lines 705a , b respectively. 805a , b away.

4g shows another variant in which two sensors 901a , b at the same axial distance as at 4e are arranged on the rotor, but in this case not in the same angular position. For the purpose of measuring the phase offset, these sensors are positioned rotated by 180 ° around the longitudinal axis of the rotor.

4h shows a further variant of the arrangement of the sensor 1001 . In this variant, the sensor is arranged centrally in the longitudinal axis of the rotor within the rotor and does not extend to an outer surface of the rotor. In addition, the sensor is arranged approximately centrally in the rotor in the axial direction. This arrangement is particularly suitable for arranging a single or multi-axis vibration sensor or a gyroscope or a rotation sensor and thereby recording the movement, speed or acceleration of the sensor, which enables a characteristic statement about the operating state of the eccentric screw pump due to the eccentric movement.

4i showed a variant of the sensor arrangement in which the sensor 1101 is also not arranged up to the outer surface of the rotor, but remains inside the rotor. Compared to the in 4h In this case, however, the sensor is arranged at a radial distance from the longitudinal axis of the rotor and is located near the outer surface of the rotor.

4y shows an embodiment in which a wired transmission of data or energy to the sensor 1201 is not required. Consistent with 4b is here an energy converter 1207 arranged adjacent to the sensor. In addition, there is also a radio transmission module in this embodiment 1209 arranged adjacent to the sensor in the rotor. As a result, the sensor signals can be sent to a receiver arranged outside the rotor, in particular outside the stator or the eccentric screw pump 1210 be transmitted.

4k shows a variant of this, in addition to the sensor 1301 also the radio transmission module 1309 directly from the energy converter 1307 is supplied with energy and to an external receiver 1310 which transmits signals.

In the two embodiments according to 4y and 4k the sensor is self-sufficient and arranged on the rotor without the need for a cable-bound signal line or cable-bound power supply and is therefore particularly advantageous in terms of assembly and at the same time robust.

the 5a-5c show the basic principle of generating a measurement signal from a measurement parameter and the power supply necessary for this to generate the measurement signal and to transmit this measurement signal.

5a shows here a sensor 2200 , which is a measurement parameter 2201 recorded and via a microcontroller 2201 a measurement signal 2204 generated and emitted. For this purpose, the sensor is directly connected to a power supply 2203 tied together.

5b shows a variant of the principle in which there is also a sensor 2300 a measurement parameter 2301 recorded and via a microcontroller 2302 a measurement signal describing this measurement parameter 2304 issues. The sensor is not directly connected to an external power supply. Instead it is an energy converter 2305 provided, the ambient energy 2303 in electrical energy for the supply of sensor 2300 and microcontroller 2302 transforms. The energy converter sends the generated energy to an energy management and storage module 2306 from which the sensor and the microcontroller are supplied with energy.

5c shows a variant based on this, with the next to the sensor 2400 , which is the measurement parameter 2401 via a microcontroller 2402 into a measurement signal 2404 implements, also an energy converter 2405 , the ambient energy 2403 converts it into electrical energy and transfers it to an energy management and storage module 2406 is present. The energy management and storage module supplies the sensor and the microcontroller 2402 with electrical energy. Furthermore, a converter or coupler is used as a wireless transmission module 2407 works and an antenna 2408 has, used to the sensor signal 2404 to be transmitted to an outside recipient.

the 6a-d show typical courses of some characteristic sensor signals which reflect measurement parameters that can be detected on the rotor or the wobble shaft.

In 6a is the dynamic stiffness 3001 (Curve with triangles), the work of damping 3002 (Curve with squares) and the surface temperature 3003 of the stator (curve with points) over the entire operating period 3010 , in which an eccentric screw pump is operated, applied. It can be seen that the surface temperature 3003 starting from a run-in phase 3011 , in which it is initially low, extends over a long period of normal operation 3012 moved in an acceptable operating window, to then in a subsequent fatigue-failure phase 3013 to increase exponentially. This is usually characterized by exceeding a limit temperature T _F 3020 . The damping work 3002 that is achieved in the rubberized stator behaves in terms of its curve shape similar to the surface temperature 3003 of the stator. The dynamic stiffness 3001 is in the running-in phase 3011 initially high at the beginning, then remains for the normal operating time 3012 almost constant, to then during the fatigue failure phase 3013 to descend.

The effects that lie behind these curves are dependent on various factors and the cause of the curve cannot therefore be explained in general. On the one hand, the initial fit between rotor and stator, for example, plays a role - an initially tight fit can lead to an initially large input of frictional energy, which then decreases. On the other hand, the dynamic stiffness of the elastomer (the stator), for example, also plays a role, which describes the ability to propagate vibrations and thus the transport of energy / temperature.

This changes in the run-in and start-up phase 3011 and, if it drops, it can lead to an increase in temperature which has to be passed through the elastomer.

6b shows the temperature profile of the surface temperature 4020 of the stator over time 4010 during the start-up behavior when an eccentric screw pump is started up once. Three typical temperature profiles T1, T2 and are shown T3 which could be recorded at three different time points at a measuring point on the stator by means of a sensor embedded in the rotor. All three temperature curves show a steep rise at the beginning, which then flattens out and levels off at a constant temperature level.

The temperature curve T2 represents a curve with the comparatively steepest rise, whereas the curve T1, although it rises less steeply, rises by a difference ΔT12 to a higher temperature level than T2. This more steeply rising temperature curve T2 correlates, for example, with a more rapidly decreasing dynamic stiffness or other properties of the elastomer of the stator. The comparison of the steady-state temperatures ΔT12 can, for example, signal a pumping situation of a medium with better lubrication properties and a lower temperature. A temperature curve T3 with a flatter curve and, in contrast, a constant temperature leveled off by a ΔT13 lower, for example, with an identical pumped medium, the pump can run at a lower speed.

6c and 6d each show the measured values of a position, speed or acceleration 5020 a position sensor arranged in the outer surface of the rotor or near the outer surface of the rotor, which can be implemented as a rotation sensor or gyro sensor, for example, in the three axial directions X, Y and Z over time 5010 . 6c shows a typical curve for an eccentric screw pump, which is in the normal operating state without significant wear. 6d In contrast, shows a pump operating state with advanced wear.

It can be seen here that the positions in the Z and Y directions 90 ° out of phase with one another have a similar course in both figures, whereas the position in the X-direction has an almost stationary value in the normal operating state, which is only subject to certain slight fluctuations due to pulsating pressure influences and axial bearing play.

6d In contrast, shows a curve progression which has a significantly greater amplitude of the Z and Y values and also a considerable deviation of the X values from a constant progression with a clear, albeit irregular, oscillation of the rotor in the x direction. All of these three characteristic curves show increased wear on the eccentric screw pump, which can be seen from both radial and axial position fluctuations, accelerations and speeds.

By measuring the in 6c and 6d The path movement shown by, for example, distance sensors or rotation sensors, on the other hand, can be used to monitor the operating state of the pump to ensure that unfavorable rotor movements due to, for example, misalignment or a wobbling movement ( 6c and 6d ) can be recognized by the play of the rotor (caused by decreasing preload of the rotor in the stator).

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 2944819 B1 [0005]
• DE 10063953 A1 [0007]
• JP 60150491 A [0007]
• DE 19649766 A [0007]
• DE 102005019063 B3 [0008]
• DE 102018113347 A1 [0009]
• WO 2018/130718 A1 [0011]

Claims (19)

Eccentric screw pump, with - a pump housing with a pump inlet opening and a pump outlet opening, - a stator arranged in the pump housing - a rotor arranged in the stator - a drive unit comprising a drive motor and a drive shaft which connects the drive motor to the rotor to transmit a torque, - the rotor being guided for a rotating movement around a rotating axis in the stator, - a state sensor for detecting a state variable of the eccentric screw pump, characterized in that the state sensor - is arranged on the rotor or the drive shaft or - with the rotor or the Drive shaft is connected by means of a signal line and is arranged at a distance from the rotor or the drive shaft, for detecting a state variable on the rotor or on the drive shaft. Eccentric screw pump after Claim 1 , characterized in that the condition sensor is arranged within the rotor or within the drive shaft. Eccentric screw pump after Claim 1 or 2 , characterized in that the condition sensor is wired to an electronic evaluation unit via a sensor cable and - the sensor cable runs within a section of the drive shaft and / or within a section of the rotor, or - the sensor cable runs through the drive shaft and possibly through a section of the rotor runs. Eccentric screw pump according to one of the preceding claims, characterized in that the drive shaft is a wobble shaft which - at its end facing the drive motor is connected to the drive motor for rotation about a drive axis, and - at its end facing the rotor with the rotor for rotation a rotor axis and is connected to the superimposed rotation about a stator axis spaced from the rotor axis. Eccentric screw pump after Claim 4 , characterized in that the wobble shaft has a wobble shaft central portion, a first universal joint and a second universal joint, and the first universal joint is inserted between the wobble shaft central portion and the drive motor and the second universal joint is inserted between the wobble shaft central portion and the rotor. Eccentric screw pump after Claim 5 , characterized in that the sensor cable - is guided into the first and / or the second universal joint, or. - is passed through the first and optionally through the second universal joint, or - is passed around the first and / or the second universal joint. Eccentric screw pump after Claim 5 or 6th , characterized in that the first universal joint is enclosed by a first sealing sleeve and the second universal joint is enclosed by a second sealing sleeve or the first and second universal joint and the wobble shaft are enclosed by a sealing sleeve, and that - In the first and / or the second Sealing sleeve or a pressure sensor is arranged in the sealing sleeve, or - A pressure line is guided into the first and / or the second sealing sleeve or in the sealing sleeve and a pressure sensor is in fluid connection with the pressure line to detect the pressure in the first and / or second sealing sleeve or in the sealing sleeve, and the pressure sensor is connected for signaling purposes to an evaluation device which is designed to detect the pressure within the first and / or second sealing sleeve or within the sealing sleeve by means of the pressure sensor. wherein the pressure sensor preferably detects the pressure of a pressure line guided into the first and / or the second sealing sleeve or into the sealing envelope or pressure medium fed via the pressure line. Eccentric screw pump according to one of the preceding claims, characterized in that the condition sensor is connected to an electronic evaluation unit for signal transmission and the electronic evaluation unit is designed to determine a deviation of an actual condition detected by the condition sensor based on the condition sensor data from a predetermined target condition to compare this determined deviation with a predetermined permissible deviation and to output an alarm signal if the determined deviation exceeds the permissible deviation. Eccentric screw pump after Claim 8 , characterized in that the electronic evaluation unit is designed to - to receive a condition sensor signal as the ACTUAL condition, - to compare the condition sensor signal with a stored normal condition sensor signal as the TARGET condition and ◯ to calculate the determined deviation as the difference between the condition sensor signal and the normal condition sensor signal, ◯ to use a predetermined permissible deviation value as the predetermined permissible deviation, and ◯ to output a value alarm signal as an alarm signal. Eccentric screw pump after Claim 8 or 9 , characterized in that the electronic evaluation unit is designed to - receive state sensor signals, - to determine a state change value as the ACTUAL state from at least two chronologically consecutive state sensor signals, and - to compare the state change value with a stored normal state change value as the target state ◯ the determined To calculate the deviation as the difference between the state change value and the normal state change value, ◯ to use a predetermined allowable deviation change value as the predetermined permissible deviation, and ◯ to output a change alarm signal as an alarm signal. Eccentric screw pump according to one of the Claims 8 - 10 , characterized in that the electronic evaluation unit is designed to - receive state sensor signals, - to determine a rate of change of state as the ACTUAL state from at least three consecutive state sensor signals, and - to compare the rate of change of state with a stored speed of normal state change as the target state, o the to calculate the determined deviation as the difference in the rate of change of state from the normal rate of change, ◯ to use a predetermined permissible speed deviation as the predetermined permissible deviation, and ◯ to output a rate of change alarm signal as an alarm signal. Eccentric screw pump according to one of the preceding Claims 8 - 11 , characterized in that the electronic evaluation unit is designed to - compare a plurality of chronologically sequential ACTUAL states with a plurality of chronologically sequential TARGET states, and - as the determined deviation, to calculate a deviation characteristic value from the comparison, - as predetermined permissible Deviation to use a predetermined permissible deviation parameter. Eccentric screw pump according to one of the preceding Claims 8 - 12th , characterized in that the eccentric screw pump has a rotor with a conical envelope and a conically tapering stator interior and the rotor and the stator can be adjusted relative to one another in the axial direction by means of an axial actuator, the electronic evaluation unit is connected and designed with the axial actuator for signal transmission, in order to - control the actuator in order to carry out an axial adjustment between rotor and stator, - during the axial adjustment process several temporally successive status sensor signals of the status sensor are recorded. Eccentric screw pump according to one of the preceding claims, characterized in that the status sensor is arranged on the drive shaft or the rotor and is further connected to a status sensor data transmission module for wireless transmission of status data to a data receiver outside the eccentric screw pump, the status sensor and the status sensor data transmission module for receiving electrical Energy is connected to an energy converter which is arranged on the rotor or on the drive shaft and which is designed to convert kinetic or thermal energy acting on it into electrical energy. Eccentric screw pump after Claim 14 , characterized in that the energy converter is selected from: - A converter based on the electromagnetic induction principle, which converts a relative rotational movement of the rotor or the wobble shaft with respect to a pump housing into electrical energy, - A converter based on the electromagnetic induction principle, which converts one from the rotation of the rotor or the wobble shaft around a rotor axis and the rotation of the rotor around an eccentric axis converts the resulting reciprocal acceleration of the rotor or the wobble shaft into electrical energy, or - a converter based on a thermoelectric principle that converts a temperature gradient into electrical energy, whereby the Converter is arranged in particular in an area that has a temperature gradient between the conveyed Medium and a pump component such as the rotor, the wobble shaft or the stator is exposed. Eccentric screw pump according to one of the preceding claims, characterized in that two state sensors are arranged on the rotor, which are arranged at two positions spaced apart from one another and the positions have a phase offset of the measured state variable, the phase offset preferably - by an axial spacing of the state sensors, which is greater or is smaller than the pitch of the rotor, or - is achieved by an angular distance between the two state sensors. Eccentric screw pump according to one of the preceding claims, characterized in that the status sensor is - a temperature sensor, - a pressure sensor, - a vibration sensor, or - an acceleration sensor. Method for controlling an eccentric screw pump, with - a pump housing with a pump inlet opening and a pump outlet opening, - driving a rotor for a rotating movement around a rotating axis in a stator by means of a drive unit, - pumping a medium from a pump inlet through the stator to a pump outlet a displacement effect between rotor and stator, - detection of a state variable of the eccentric screw pump, characterized in that the state variable is detected by means of a state sensor which - is arranged on the rotor or the drive shaft or - is connected to the rotor or the drive shaft by means of a signal line and is arranged at a distance from the rotor or the drive shaft, and a state variable on the rotor or on the drive shaft is detected, the eccentric screw pump preferably having a rotor with a conical envelope and a conically tapering stator interior and the rotor and the stator are adjusted relative to one another in the axial direction by means of an axial actuator, and - the rotor and the stator are adjusted axially to one another by means of the actuator, and - several successive state sensor signals of the state sensor are recorded during the axial adjustment process. Procedure according to Claim 18 , characterized in that the state variable is detected during the pumping process and that the axial adjustment process is carried out during the pumping process.

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