EP4747502A1 - Rotary pump for conveying a fluid and method for determining the operational condition of a rotary pump - Google Patents

Abstract

A rotary pump for conveying a fluid is proposed, comprising a pump housing (2) with an inlet (3) for receiving the fluid, an outlet (4) for discharging the fluid, a pump shaft (6) configured for rotating about an axial direction (A), at least one impeller (5) fixedly mounted on the pump shaft (6), and a bearing assembly (7) comprising a bearing housing (71), wherein the bearing assembly (7) is configured for supporting the pump shaft (6). A sensor assembly (9) is arranged adjacent to the pump shaft (6) and configured for measuring a magnetic signal generated by the pump shaft (6), wherein the sensor assembly (9) comprises at least one magnetic sensor (92) configured as a non-contact magnetic sensor (92). In addition, a method for determining the operational condition of such a rotary pump (1) is proposed.

Description

Rotary pump for conveying a fluid and method for determining the operational condition of a rotary pump

The invention relates to a rotary pump for conveying a fluid and to a method for determining the operational condition of a rotary pump in accordance with the preamble of the independent claim of the respective category.

Rotary pumps for conveying a fluid, for example a liguid such as water, are used in many different industries. Examples are the oil and gas industry, the power generation industry, the chemical industry, the water industry or the pulp and paper industry. In the water industry rotary pumps are used, for example, for conveying municipal water (wastewater and clean water), for desalination or for irrigation. Rotary pumps have at least one impeller and a pump shaft for rotating the impeller. The at least one impeller may be configured for example as a radial impeller or as an axial or semi-axial impeller or as a helicoaxial impeller. Furthermore, the impeller may be configured as an open impeller or as a closed impeller, where a shroud is provided on the impeller, said shroud at least partially covering the vanes of the impeller. In many cases rotary pumps are configured as centrifugal pumps.

A rotary pump or a centrifugal pump may be designed as a single stage pump having only one impeller mounted to the pump shaft or as a multistage pump comprising a plurality of impellers, wherein the impellers are arranged one after another on the pump shaft. The impellers may be arranged in an in-line arrangement, where the axial thrust generated by a single impeller is directed in the same direction for all impellers, or in a back-to-back arrangement, where the axial thrust generated by a first group of impellers is directed in the opposite direction as the axial thrust generated by a second group of impellers. Nowadays in many applications the most efficient use of the rotary pump is strived for. It is desirable to have the highest possible ratio of the power, especially the hydraulic power, delivered by the pump to the power needed for driving the pump. This desire is mainly based upon an increased awareness of environment protection and a responsible dealing with the available resources as well as on the increasing costs of energy. Therefore, all rotary pumps regardless of their embodiment are sized and optimized to work at or near the best efficiency point (BEP). The BEP is that point in the pump head curve where the efficiency of the pump is the highest.

For many applications it is desired to monitor the operating condition of the rotary pump, for example, to detect, when the pump is moving away from an operation at or near the BEP. Preferably, the performance of the rotary pump should be determined and monitored in real time during operation of the pump. Typically, this requires a plurality of different sensors, for example, different pressure sensors for measuring the pressure of the fluid at the inlet of the pump and for measuring the pressure at the outlet of the pump, flow sensors for measuring the flow generated by the pump, temperature and/or vibration sensors for controlling the bearing(s) or detecting vibrations of the pump shaft and so on. Thus, the monitoring of the operational condition of a rotary pump in real time during operation of the pump requires a lot of efforts and equipment, such as sensors, which makes the monitoring quite expensive and laborious.

Starting from this state of the art it is therefore an object of the invention to propose a rotary pump for conveying a fluid, which renders possible a very simple and reliable determination of the operation condition of the pump in real time. Furthermore, it is an object of the invention to propose a method for determining the operational condition of a rotary pump, wherein the method is performable with a reduced amount of equipment such as sensors.

The subject matter of the invention satisfying this object is characterized by the features of the independent claims.

Thus, according to the invention, a rotary pump for conveying a fluid is proposed, comprising a pump housing with an inlet for receiving the fluid, an outlet for discharging the fluid, a pump shaft configured for rotating about an axial direction, at least one impeller fixedly mounted on the pump shaft, and a bearing assembly comprising a bearing housing, wherein the bearing assembly is configured for supporting the pump shaft. A sensor assembly is arranged adjacent to the pump shaft and configured for measuring a magnetic signal generated by the pump shaft, wherein the sensor assembly comprises at least one magnetic sensor configured as a non-contact magnetic sensor.

Providing the sensor assembly with the at least one non-contact magnetic sensor renders possible to determine the operational condition of the rotary pump in real time without the necessity of a plurality of pressure sensors, flow sensors and the like. By means of the magnetic sensor measuring the magnetic signal generated by the rotating pump shaft the operation condition of the rotary pump is reliably determinable. If, for example, the load acting on the shaft changes or a shaft deflection occurs, this results in a change of the magnetic properties of the pump shaft. Therefore, the magnetic field generated by the rotating pump shaft changes and therewith the magnetic signal emitted by the pump shaft. This change or the variation in the magnetic signal generated by the pump shaft is detected by the magnetic sensor of the sensor assembly, which in turn indicates that a change in the operational condition of the pump has occurred, for example a change in the performance of the rotary pump.

Furthermore, according to the invention a method for determining the operational condition of a rotary pump configured according to the invention is proposed, which method is characterized in that: calibration data for the rotary pump are determined and stored in a control system; during operation, the magnetic signal generated by the pump shaft is measured by means of the sensor assembly; the magnetic signal is transferred to the control system; the magnetic signal is compared with the calibration data; the operational condition of the rotary pump is determined based on the comparison of the magnetic signal with the calibration data.

As an option, it is also possible to combine the magnetic signal with other measured signals or data. As an example, when the rotary pump is operated with a variable frequency drive (VFD), the accuracy of the determination of the operational condition may be increased by combining the magnetic signal with the rotational speed of the pump shaft.

According to this method calibration data for the rotary pump are determined and stored. These pump-specific calibration data can be collected, for example, by the manufacturer during the performance test prior to the delivery of the pump to the customer. During the performance test of the pump, the pump is usually operated at several different points of the pump head curve. The pump head curve for a rotary pump indicates the relationship between the head generated by the pump and the flow generated by the pump. Thus, during the performance test it is very easy to collect the calibration data. For each operational point, at which the rotary pump is operated during the performance test, only one additional reading is required, namely the signal measured by the magnetic sensor(s) of the sensor assembly. Said signal is then stored as a calibration data for the particular operational point, at which the pump is operated.

Preferably, the calibration data are determined at a plurality of different points of the pump head curve. For example, at each operational point, at which the rotary pump is operated during the performance test by the manufacturer of the pump at the factory, the magnetic signal is determined by means of the sensor assembly and stored as a calibration data for this particular operational point of the rotary pump. Thus, after the performance test, a plurality of calibration data has been acquired, which are all allocated to specific points of the pump head curve. Therefore, during operation of the pump, e.g. after deployment at the customer’s location, the actual value measured by the sensor assembly can be compared with the calibration data. The operational condition of the rotary pump can then be determined based on the comparison of the actual magnetic signal with the calibration data. If there is a deviation of the actual magnetic signal and the calibration data for the operational point, at which the rotary pump is actually operated, the operational condition of the rotary pump differs from the desired operational condition. Based on the detected difference, it can be decided, whether countermeasures have to be initiated or not.

The pump head curve is only an example for collecting the calibration data. It is also possible to use - as an alternative or in addition - other pump performance curves to collect the calibration data. The term pump performance curve designates each curve which is indicative for the performance of the pump. Thus, the pump performance curve can also refer, for example, to the power consumption, the pump efficiency or the net positive suction head (NPSH) generated by the rotary pump.

Irrespective of which specific pump performance curve(s) is/are used, it is preferred that the calibration data are determined at a plurality of different points of the pump performance curve. The rotary pump and the method according to the invention render possible a very easy and reliable surveillance of the rotary pump and reduce the required equipment for the surveillance.

The calibration data are, for example, determined by the manufacturer of the pump prior to the delivery of the pump to the customer and stored in a control system. The customer only has to connect the sensor assembly with the control system to monitor the operational condition of the pump. This ‘plug-in’ solution is very convenient, in particular for the customer or the operator, and does not require any additional equipment such as pressure sensors or the like.

It is also possible that the magnetic signal is transferred to the control system by a wireless communication. In particular in larger plants or in complex processes the control system can be integrated in a central control unit, such as a distributed control system (DCS) and for such configuration a wireless communication between the sensor assembly and the control system can be advantageous.

According to some embodiments the control system generates a warning, when the operational condition leaves a presettable range. Thus, when the difference between the actual magnetic signal measured by means of the sensor assembly and the corresponding calibration data, associated with the actual operating point, at which the rotary pump is operating, exceeds a predefined limit, the control system can create a warning alerting the operator of the pump. It is also possible, that the control system automatically initiates actions when the predefined limit is exceeded. For example, the control system could cause a shutdown of the rotary pump.

It is possible that the warning is indicated at the rotary pump, for example as a visual or an acoustic signal or as an error message or a warning message on a display.

Furthermore, it is also possible that the warning is indicated at a remote location away from the rotary pump, for example on a mobile device of an operator or in a control room.

In addition, the control system, in which the calibration data are stored, can be provided at the same location as the rotary pump, for example the control system can be included in a main control device for controlling the operation of the rotary pump. It is also possible that the control system is located at a remote location away from the rotary pump, for example in a control room or in a local process control system or in a remote DCS. Furthermore, it is also possible that the control system is integrated in or connected to a cloud system, e.g. by means of a gateway.

Regarding the configuration of the rotary pump according to the invention, it is preferred, that the sensor assembly comprises a plurality of magnetic sensors, each of which is configured as a non-contact magnetic sensor, wherein the plurality of magnetic sensors is arranged around the pump shaft. By arranging a plurality of magnetic sensors around the pump shaft the measuring sensitivity of the sensor assembly can be increased, which enhances the measuring accuracy and the reliability of the measurement of the magnetic signal.

According to a preferred embodiment, the sensor assembly comprises four magnetic sensors equidistantly arranged around the pump shaft.

For particularly reliably measuring the magnetic signal generated by the pump shaft it is preferred, that each magnetic sensor is arranged at a radial distance from the pump shaft, wherein the radial distance is between 0.1 millimeter and 10 millimeter, preferably at most one millimeter or at most 0.5 millimeter. Depending on the specific application or the specific configuration of the rotary pump an optimized value for the radial distance can be determined.

Regarding the arrangement of the magnetic sensor(s) with respect to the axial direction, it is preferred, that each magnetic sensor is arranged at a location between the pump housing and the bearing housing with respect to the axial direction.

For practical reasons it is preferred that the sensor assembly comprises a sensor housing, in which each magnetic sensor is arranged. Thus, the sensor assembly can be configured as a constructional unit or a single component, which is arranged around the pump shaft.

According to a preferred configuration the rotary pump comprises an adapter connecting the pump housing with the bearing housing, wherein each magnetic sensor is arranged within the adapter.

Furthermore, it is a preferred location for the magnetic sensors to be arranged adjacent to the bearing assembly. Therefore, the sensor housing is preferably fixed to the bearing housing. Further advantageous measures and embodiments of the invention will become apparent from the dependent claims.

The invention will be explained in more detail hereinafter with reference to embodiments of the invention and with reference to the drawings. There are shown in a schematic representation:

Fig. 1 : a cross-sectional view of an embodiment of a rotary pump according to the invention,

Fig. 2: a schematic cross-sectional view of the sensor assembly in a cut perpendicular to the axial direction, and

Fig. 3: a flow chart illustrating an embodiment of a method according to the invention.

Fig. 1 shows a schematic cross-sectional view of an embodiment of a rotary pump according to the invention, which is designated in its entity with reference numeral 1. The pump 1 is designed as a centrifugal pump for conveying a fluid, for example a liquid such as water.

The rotary pump 1 comprises a pump housing 2 having an inlet 3 and an outlet 4 for the fluid to be conveyed. The inlet 3 is arranged on a suction side and receives the fluid having a suction pressure. The outlet 4 is arranged on a discharge side and discharges the fluid having a discharge pressure, wherein the discharge pressure is larger than the suction pressure. The pump 1 further comprises an impeller 5 for conveying the fluid from the inlet 3 the outlet 4 and for pressurizing the fluid from the suction pressure such that the fluid is discharged at the outlet 4 with the discharge pressure. The impeller 5 is configured as a radial impeller 5. Of course, the rotary pump 1 can also be configured with other types of impellers 5.

The pump 1 further comprises a pump shaft 6 for rotating the impeller 5 about an axial direction A. The axial direction A is defined by the axis of the pump shaft 6. A direction perpendicular to the axial direction A is referred to as a radial direction. The pump shaft 6 extends from a drive end 61 to a non-drive end. In this embodiment of the pump 1 the drive end 61 of the pump shaft 6 is located outside of the pump housing 2 and may be connected to a drive unit (not shown) for driving the rotation of the pump shaft 6 about the axial direction A. The drive unit may comprise, for example, an electric motor. The impeller 5 is mounted to the non-drive end of the pump shaft 6 in a torque proof manner.

The rotary pump 1 further comprises a bearing assembly 7 having a bearing housing 71 , in which a bearing unit 72 is arranged. The bearing unit 72 is configured to support the pump shaft 6 with respect to the axial direction A and with respect to the radial direction.

The embodiment of the rotary pump 1 illustrated in Fig. 1 is configured as an horizontal, single stage centrifugal pump 1 with an overhung impeller design. This type of rotary pump is for example used as a process pump. Horizontal means that the pump shaft 6 for rotating the impeller 5 extends horizontally, i.e. perpendicular to the direction of gravity. Single stage means that the rotary pump 1 has only one impeller 5. Overhung means that the pump shaft 6 with the impeller 5 is only supported on one side of the impeller 5. Here, the impeller 5 is arranged at the nondrive end of the pump shaft 6.

It has to be understood that the invention is not restricted to this type of rotary pump 1. In other embodiments, the rotary pump may be configured for example as a multistage pump having at least two impellers mounted on the pump shaft or as a vertical pump, meaning that during operation the pump shaft 6 is extending in the vertical direction, which is the direction of gravity. Furthermore, it is also possible that the rotary pump according to the invention is configured with a between-bearing design of the impeller(s). Between-bearing means, that the impeller(s) is/are supported on both sides regarding the axial direction A, i.e. the impeller(s) is/are arranged between two bearing assemblies.

The single stage rotary pump 1 illustrated in Fig. 1 further comprises - as it is per se known in the art - an adapter 8 arranged regarding the axial direction A between the pump housing 2 and the bearing housing 71. The adapter 8 is fixed both to the pump housing 2 and to the bearing housing 71 , so that the adapter 8 firmly connects the bearing assembly 7 with the pump housing 2. The adapter 8 is also referred to as lantern 8.

According to the invention, the rotary pump 1 further comprises a sensor assembly 9, which is arranged adjacent to the pump shaft 6 and configured for measuring a magnetic signal generated by the pump shaft 6, wherein the sensor assembly 9 comprises at least one magnetic sensor 92 (Fig. 2) configured as a non-contact magnetic sensor 92.

In the embodiment of the rotary pump 1 illustrated in Fig. 1 the sensor assembly 9 comprises a plurality of magnetic sensors 92, each of which is configured as a noncontact magnetic sensor 92, i.e. as a magnetic sensor 92 that has no physical contact with the pump shaft 6.

Fig. 2 shows a schematic cross-sectional view of the sensor assembly 9 in a cut perpendicular to the axial direction A. In this embodiment of the rotary pump 1 , the sensor assembly 9 comprises four magnetic sensors 92 that are equidistantly arranged around the circumference of the pump shaft 6 without contacting the pump shaft 6. Thus, the angular distance between adjacent magnetic sensors 92 is 90°, at least approximately.

As it is known in the art, a magnetic sensor 92 is a sensor that converts the magnitude and the variations of a magnetic field into electric signals. The magnetic sensor(s) 92 of the sensor assembly 9 is/are arranged and configured for measuring a magnetic signal generated by the pump shaft 6. Preferably, each magnetic sensor 92 is configured as magneto-resistive sensor 92 for measuring the magnetic properties of the pump shaft 6.

In particular, the magnetic sensor 92 may be configured as a force sensor for measuring the forces acting on the pump shaft 6, for example axial forces or bending forces. The magnetic sensor 92 can be configured, for example, for emitting an alternating magnetic field, which enters the pump shaft 6. The alternating magnetic field is influenced or modified by the mechanical forces or the loads acting on the pump shaft 6. These modifications of the alternating magnetic field are measured by the magnetic sensor 92 and evaluated for example by a software product to determine the forces acting on the pump shaft 6.

Furthermore, the magnetic sensor 92 may be configured as a torque sensor for measuring the forces acting on the pump shaft 6 as well as the torque acting on the pump shaft 6.

It is also possible to configure the sensor assembly 9 with a combination of magnetic sensor(s) 92 configured as force sensor(s) and magnetic sensor(s) 92 configured as torque sensor(s). Magnetic sensors 92 configured, for example, as non-contact magnetic force sensors or as non-contact magnetic torque sensors are commercially available in a large variety and therefore a more detailed description is not necessary in this application.

Typically, the pump shaft 6 consists of a material or comprises a material having sufficient magnetic properties to generate a magnetic signal which is strong enough to be measured by the magnetic sensor(s) 92. For example, all martensitic and most precipitation hardenable stainless steels are ferromagnetic, so that they can interact with magnetic sensors 92 to determine magnetic properties of the pump shaft 6. Also pump shafts 6 consisting of or containing a duplex stainless steel usually have sufficiently strong ferromagnetic properties to interact with magnetic sensors 92. Although the austenite phase is not ferromagnetic, the ferromagnetic properties of the ferrite phase are often strong enough so that a pump shaft 6 made from a duplex stainless steel can sufficiently strongly interact with the magnetic sensor(s) 92.

It has to be understood that the number of four magnetic sensors 92 is exemplary, only. In other embodiments of the rotary pump 1 the sensor assembly 9 may comprise less than four or even more than four magnetic sensors 92.

In some embodiments of the rotary pump 1 the sensor assembly 9 can comprise only one magnetic sensor 92, which is configured for example as a torque sensor for measuring the torque acting on the pump shaft 6.

In some embodiments of the rotary pump 1 the sensor assembly 9 can comprise exactly two magnetic sensors 92, for example one magnetic sensor 92 for measuring the axial thrust acting on the pump shaft 6, and one magnetic sensor 92 for measuring a bending of the pump shaft 6.

As can be best seen in Fig. 2, the sensor assembly 9 comprises a sensor housing 91 in which each magnetic sensor 92 is arranged. The sensor housing 91 has a central opening, through which the pump shaft 6 passes, so that the sensor housing 91 surrounds the pump shaft 6. The magnetic sensors 92 are fixed to the sensor housing 91. As already said, all magnetic sensors 92 are configured as non-contact magnetic sensors 92. Each magnetic sensor 92 is arranged at a radial distance R from the pump shaft 6. The optimal radial distance R depends on the specific configuration of the rotary pump 1. For many configurations it is preferred that the radial distance R is at most one millimeter preferably at most half a millimeter. Regarding the axial direction A, all magnetic sensors 92 are preferably arranged at the same axial position.

Furthermore, it is preferred, that all magnetic sensors 92 are arranged with respect to the axial direction A at a location between the pump housing 2 and the bearing housing 71. Even more preferred the magnetic sensors 92 are arranged adjacent to the bearing housing 71. Thus, regarding the embodiment of the rotary pump 1 illustrated in Fig. 1 all magnetic sensors 92 are arranged within the adapter 8. As it can be seen in Fig. 1 , the sensor housing 91, in which all the magnetic sensors 92 are arranged, is fixed to the bearing housing 71 , for example by means of screws (not shown). The sensor housing 91 attached to the bearing housing 71 is surrounded by the adapter 8.

Referring now to Fig. 3 an embodiment of the method for determining the operational condition of a rotary pump 1 is described. The rotary pump 1 can be configured as shown in and described referring to Fig. 1. Of course, the method according to the invention can also be applied to other configurations of the rotary pump 1 , as long as the rotary pump 1 is configured with at least one of the magnetic sensors 92 for measuring a magnetic signal generated by the pump shaft 6.

The method for determining the operational condition of the rotary pump 1 comprises the step of determining calibration data C for the rotary pump 1 and storing the calibration data C in a control system 100. The control system 100 comprises a data unit 101, in which the calibration data C are stored, an evaluation unit 102, where an analysis of the magnetic signals measured by the magnetic sensors 92 is performed, and a output unit 103, where a pump specific output is generated.

The control system 100 may be provided at the rotary pump 1 or at the same location as the rotary pump 1 , for example the control system 100 can be included in the main control device which controls the operation of the rotary pump 1. In other embodiments, the control system 100 is located at a remote location away from the rotary pump 1, for example in a central control room for controlling the facility, in which the rotary pump 1 is deployed. The control system 100 can also be included in a local process control system or in a remote distributed control system (DCS). In still other embodiments the control system 100 is integrated in or connected to a cloud system, e.g. by means of a gateway. Preferably, the pump specific calibration data C are determined during the performance test of the rotary pump 1 prior to the delivery to the customer or the operator of the rotary pump 1. The manufacturer of the rotary pump 1 usually executes a performance test before the rotary pump 1 is delivered to the customer or the operator, respectively, and commissioned. During the performance test the rotary pump 1 is operated in a test bed at a plurality of different operational points on the pump head curve. The flow delivered by the rotary pump 1 is stepwise increased (or decreased) and for each flow the head generated by the rotary pump 1 is measured. By this procedure the pump head curve of the rotary pump 1 is determined.

During this performance test for each flow, at which the pump 1 is operated, the magnetic signal or the magnetic signals measured by the magnetic sensors 92 are determined in addition to measuring the generated head. The magnetic signal can be indicative, for example, for the axial thrust acting on the pump shaft 6, or for the torque or the load acting on the pump shaft 6, or for a bending or a radial displacement of the pump shaft 6.

At the end of the performance test for each operating point of the pump head curve, at which the rotary pump 1 has been operated, a calibration data point for the magnetic signal measured by the magnetic sensors 92 is available. Thus, the pumpspecific calibration data C constitutes a set of data allocating a specific magnetic signal to each operating point of the pump head curve. These calibration data C are stored in the control system 100, more precisely, in the data unit 101 of the control system 100.

Thus, the acquisition and the storage of the calibration data C is preferably performed by the manufacturer of the pump prior to commissioning the rotary pump at the customer’s site. A considerable advantage is the fact, that the acquisition of the calibration data C does not require a big effort. It is just one additional measurement or sensor reading per operating point during the performance test of the rotary pump 1.

After the delivery of the rotary pump 1 to the customer or the operator and after the commissioning of the rotary pump 1, the magnetic sensors 92 are used for determining the operational condition of the rotary pump 1 in real time during operation of the rotary pump 1. The magnetic sensors 92 measure the actual magnetic signal of the pump shaft 6 and transfer the actual value of the magnetic signal to the data unit 101 of the control system 100 as indicated by the arrow T in Fig. 3. In the evaluation unit 102 the actual value of the magnetic signal is compared with the calibration data C. It is analyzed, whether the actual value of the magnetic signal is equal to the magnetic signal stored in the calibration data C for the specific operating point, i.e. the specific point on the pump head curve, at which the rotary pump 1 is actually operating. If the actual value of the magnetic signal equals the corresponding value of the calibration data, the performance of the rotary pump 1 is alright.

If the actual value of the magnetic signal as measured by the magnetic sensors 92 deviates from the calibration data for the operating point, at which the rotary pump 1 is actually operating, the performance of the rotary pump 1 differs from the desired performance. In this case the evaluation unit 102 analyses the performance of the rotary pump 1 based on the deviation of the actual magnetic signal as measured by the magnetic sensors 92 from the corresponding calibration data C. During said analysis both the magnitude and the sign of the deviation can be used for identifying the cause or potential causes, why the rotary pump 1 is not performing as expected.

According to a preferred embodiment of the method, the control system 100 generates a warning, when the operational condition of the rotary pump 1 leaves a presettable range, i.e. exceeds or falls below a predefined limit.

The result of the analysis performed by the evaluation unit 102 is passed to the output unit 103. The output unit 103 generates the warning. The warning can be an acoustic signal or a visual signal. The warning can include additional information resulting from the analysis, such as potential causes for the non-satisfying performance of the rotary pump 1 , recommendations to improve the performance, or an alert.

It is also possible that the output unit 103 receives additional information, e.g. regarding the operational data of the rotary pump 1 , such as power consumption, flow, rotational speed of the impeller 5 and so on. Said additional information is indicated by the arrow I in Fig. 3. Thus, the warning generated in the output unit 103 can be influenced by the additional information I.

The warning generated by the output unit 103 is delivered to the operator 200 of the rotary pump 1. The operator can take actions as indicated by the box 300, and said actions are then applied to the rotary pump 1 as indicated by the arrow with the reference numeral X in Fig. 3. Particularly preferred the method for determining the operational condition of a rotary pump according to the invention comprises the following steps:

The calibration C for the rotary pump 1 are collected and stored in the control system 100, wherein the calibration data C comprise a plurality of calibration data points, wherein each calibration data point is or represents the magnetic signal generated by the pump shaft 6 at an operating point of the pump head curve of the rotary pump 1. During operation of the rotary pump 1, the magnetic signal generated by the pump shaft 6 is measured by means of the sensor assembly 9, the magnetic signal is transferred to the control system 100 and the magnetic signal is compared with the calibration data point for the operating point, at which the rotary pump is operated.

The operational condition of the rotary pump 1 is determined based on the comparison of the magnetic signal with the calibration data C.

Thus, the calibration data C comprise a plurality of calibration data points and each of the calibration data points corresponds to a specific operating point on the or a pump head curve. Preferably, each calibration data point is based on the magnetic signal of the pump shaft 6 measured by means of the sensor assembly 9 at a specific operating point on the pump head curve. Therefore, each calibration data point is representative for the magnetic signal generated by the pump shaft, when the rotary pump is operated at a specific operating point on the pump head cure of the rotary pump 1.

Claims

Patent claims

1. A rotary pump for conveying a fluid, comprising a pump housing (2) with an inlet (3) for receiving the fluid, an outlet (4) for discharging the fluid, a pump shaft (6) configured for rotating about an axial direction (A), at least one impeller (5) fixedly mounted on the pump shaft (6), and a bearing assembly (7) comprising a bearing housing (71), wherein the bearing assembly (7) is configured for supporting the pump shaft (6), characterized in that a sensor assembly (9) is arranged adjacent to the pump shaft (6) and configured for measuring a magnetic signal generated by the pump shaft (6), wherein the sensor assembly (9) comprises at least one magnetic sensor (92) configured as a non-contact magnetic sensor (92).

2. A rotary pump in accordance with claim 1 , wherein the sensor assembly (9) comprises a plurality of magnetic sensors (92), each of which is configured as a non-contact magnetic sensor (92), and wherein the plurality of magnetic sensors (92) is arranged around the pump shaft (6).

3. A rotary pump in accordance with claim 2, comprising four magnetic sensors (92) equidistantly arranged around the pump shaft (6).

4. A rotary pump in accordance with anyone of the preceding claims, wherein each magnetic sensor (92) is arranged at a radial distance (R) from the pump shaft (6), wherein the radial distance (R) is between 0.1 millimeter and

10 millimeter, preferably at most one millimeter or at most 0.5 millimeter.

5. A rotary pump in accordance with anyone of the preceding claims, wherein each magnetic sensor (92) is arranged at a location between the pump housing (2) and the bearing housing (71) with respect to the axial direction (A).

6. A rotary pump in accordance with anyone of the preceding claims, wherein the sensor assembly (9) comprises a sensor housing (91), in which each magnetic sensor (92) is arranged.

7. A rotary pump in accordance with anyone of the preceding claims, comprising an adapter (8) connecting the pump housing (2) with the bearing housing (7), wherein each magnetic sensor (92) is arranged within the adapter (8).

8. A rotary pump in accordance with anyone of claims 6-7, wherein the sensor housing (91) is fixed to the bearing housing.

9. A method for determining the operational condition of a rotary pump configured according to anyone of the preceding claims, characterized in that: calibration data (C) for the rotary pump (1) are determined and stored in a control system (100); during operation, the magnetic signal generated by the pump shaft (6) is measured by means of the sensor assembly (9); the magnetic signal is transferred to the control system (100); the magnetic signal is compared with the calibration data (C); the operational condition of the rotary pump (1) is determined based on the comparison of the magnetic signal with the calibration data (C).

10. A method in accordance with claim 9, wherein the calibration data (C) are determined at a plurality of different points of a pump performance curve.

11. A method in accordance with anyone of claims 9-10, wherein the magnetic signal is transferred to the control system (100) by a wireless communication.

12. A method in accordance with anyone of claims 9-11 , wherein the control system (100) generates a warning, when the operational condition leaves a presettable range.

13. A method in accordance with claim 12, wherein the warning is indicated at the rotary pump (1).

14. A method in accordance with anyone of claims 12-13, wherein the warning is indicated at a remote location away from the rotary pump (1).

15. A method in accordance with anyone of claims 9-14, wherein the control system (100) is located at a remote location away from the rotary pump (1).