EP3543537B1 - Pump unit and method for monitoring the liquid situation in a seal assembly in a pump unit - Google Patents

Description

The invention relates to a pump unit and a method for monitoring or detecting a change in concentration in a liquid reservoir in a sealing arrangement in a pump unit.

In the case of centrifugal pump units with a dry-running electric drive motor, it is necessary to seal the pump chamber with the impeller rotating in it from the drive motor. For this purpose, the drive shaft is passed through a sealing arrangement. It is known to use two spaced apart seals with a liquid reservoir in between. Such liquid reservoirs can be filled with oil or a glycol-water mixture, for example. If the first seal facing the pump chamber fails, the medium to be conveyed, for example water, penetrates the liquid reservoir. It is desirable to be able to detect this early on in order to be able to replace the seal. In the case of oil reservoirs, sensors are known which can detect penetrating water. If a glycol-water mixture is used in the liquid reservoir, however, it is much more difficult to detect penetrating water. For this it is necessary to record a change in the water concentration. Due to the changing operating and environmental conditions, this is not always easily possible.

Out US 2014/0116513 A1 a seal flushing system is known according to which a seal is flushed in order to prevent substances from penetrating into the seal and to ensure sufficient lubrication of the seal. A concentration sensor is located in the seal flush system. However, this system requires a system for circulating the liquid to flush the seal.

From the WO2017 / 221217 a pump unit with an electric drive motor and at least one impeller connected to the drive motor via a shaft is known, the shaft extending between the drive motor and the impeller through at least one sealing arrangement with a liquid reservoir.

The object of the invention is to provide an improved pump assembly and a method for monitoring a liquid reservoir in a sealing arrangement of a pump assembly, which makes it possible to reliably detect penetrating liquid in a liquid reservoir.

This issue is achieved by a pump assembly with the features specified in claim 1 and by a method for detecting a change in concentration in a liquid reservoir with the features specified in claim 21. Preferred embodiments emerge from the associated subclaims, the following description and the attached figures.

The pump assembly according to the invention has an electric drive motor and at least one impeller connected to the drive motor via a shaft. The shaft extends between the drive motor and the impeller through at least one sealing arrangement. This sealing arrangement has a liquid reservoir. For this purpose, the sealing arrangement preferably has at least two seals, between which the liquid reservoir is formed in the form of a chamber filled with liquid. The liquid reserve is used to detect leaks and to prevent water from entering the dry engine compartment. In addition, the liquid in the chamber can be used for cooling. The electric drive motor is in such a configuration preferably designed to run dry. I. E. the sealing arrangement is located between the liquid-filled pump chamber in which the impeller rotates and the electric drive motor located in the dry. The pump chamber can in particular be filled with water if the pump assembly is designed to convey water, for example fresh water or waste water.

According to the invention, at least one concentration sensor for detecting a change in concentration in the liquid reservoir is formed on the liquid reservoir. The concentration sensor can for example be designed to detect the concentration of a second liquid in a first liquid of the liquid reservoir, in particular the concentration of water in glycol or vice versa. However, other liquid mixtures can also be used, in particular mixtures of more than two liquids. For example, an oil-glycol mixture may contain further additives. The concentration sensor is designed to detect changes in an initially set concentration of the various liquids in the liquid reservoir. The concentration sensor can be designed in such a way that it is immersed in the liquid or that it detects the concentration without contact from the outside, e.g. through a partition. According to the invention, at least one second sensor for detecting at least one further parameter of the liquid reservoir is also arranged on or in the liquid reservoir. Both the concentration sensor and the at least one second sensor are connected to an evaluation device in such a way that the evaluation device receives and can further process the measured values that are recorded by the sensors.

The evaluation device can be integrated into an electronic control or regulating device arranged directly on the pump assembly, in particular a control device for controlling or regulating the drive motor. For this purpose, the evaluation device can be arranged, for example, in an electronics housing of the pump assembly. However, it is also possible to design the evaluation device as a separate electronic component or to arrange it further away from the sensor device or the pump assembly, for example as a cloud or network-implemented evaluation device. The evaluation device or parts of the evaluation device could also be inserted directly into the sensor or a sensor housing of the first and / or be integrated into the second sensor. It is also conceivable to distribute the functionality of the evaluation device to several electronic units or processors in different components.

According to the invention, the evaluation device is designed such that it evaluates at least one measured value from the concentration sensor, taking into account at least one measured value recorded by the at least one second sensor. This has the advantage that changes in the operating state, which have an influence on the measured value of the concentration sensor and can falsify its measurement result, can be recorded and taken into account or compensated. Thus, the parameter which is detected by the second sensor can be a parameter which characterizes a certain operating state or characterizes changes in the operating states and / or environmental conditions. This makes it possible to compensate or correct the changes in the measured value of the concentration sensor on the basis of the measured values of the at least one second sensor, so that a more precise concentration measurement becomes possible. It is to be understood that several second sensors can also be provided or a second sensor which detects more than one parameter at the same time. For example, the second sensor can detect the temperature and / or the pressure or alternatively or additionally vibrations and / or structure-borne noise.

The at least one second sensor is preferably a temperature sensor or a sensor which detects at least one temperature-dependent parameter. Such a temperature-dependent parameter can be any parameter which is dependent on the temperature, in particular is proportional to the temperature. Such a temperature-dependent parameter thus enables indirect temperature detection.

The evaluation device is particularly preferably designed in such a way that it evaluates at least one measured value from the concentration sensor, taking into account at least one temperature measured value or temperature-dependent parameter recorded by the at least one second sensor. In particular, as already described above, the evaluation device is designed in such a way that it corrects or compensates for the measured value of the concentration sensor on the basis of the temperature measured value or temperature-dependent parameter that is recorded by the at least second sensor. In this way, the influence of temperature on the concentration measurement can be eliminated. This correction can be based directly on a recorded temperature measurement value or on a parameter which is temperature-dependent, for example a vibration signal. There is a direct or an indirect temperature-dependent compensation.

The concentration sensor is preferably designed as an ultrasonic sensor, as an optical sensor or as a capacitive sensor. In the case of an ultrasonic sensor, an ultrasonic generator, for example a piezo element, is preferably designed and arranged on the liquid reservoir such that it sends an ultrasonic signal into the liquid reservoir, which is then reflected on an opposite wall. The reflected signal is picked up by a measuring sensor, which is preferably also formed by the sound generator or can be integrated with it to form a structural unit. When the concentration changes, the speed of sound changes and thus the received reflected ultrasound signal changes, so that changes in concentration can be determined by the evaluation device. The speed of sound is not only dependent on the concentration but also on the temperature of the medium, which is why it is preferred to use the at least one second sensor to detect the temperature and use it to compensate for the detected ultrasound signal.

Thus, as described above, the ultrasonic sensor can be a sensor that works according to the reflection principle. Alternatively, however, an ultrasonic sensor can also be used in which a transmitter is arranged on one side and a receiver is arranged on the opposite side, without the signal being reflected on a reflector.

A first possible consideration of different operating states when detecting changes in concentration by the concentration sensor can take place in such a way that the evaluation device is designed in such a way that it only evaluates a measured value of the concentration sensor if the measured value recorded by the at least one second sensor and in particular a measured temperature value detected by the second sensor is below a predetermined maximum limit value, preferably a predetermined maximum temperature limit value. I. E. For example, the concentration measurement can be suspended above a certain operating temperature at which reliable measurement results can no longer be expected.

Alternatively or additionally, the evaluation device can be designed in such a way that it evaluates a measured value from the concentration sensor only if the measured value recorded by the at least one second sensor and in particular a temperature measured value recorded by the second sensor is above a predetermined minimum limit value, ie preferably above a specified minimum temperature limit value. For example, it can be ensured that the concentration measurement is completely suspended at temperatures that are too low, at which no error-free measurement result is to be expected.

According to a possible embodiment of the invention, the evaluation device is designed such that it outputs an alarm signal based on a measured value recorded by the concentration sensor if this at least one measured value or a characteristic value derived from the measured value reaches a predetermined concentration limit value. In addition, it is possible for the evaluation device to output a switching or control signal which can be detected by a control device and which can be used to switch off the pump assembly based on this signal in order to prevent further defects. On the basis of the alarm signal, it can be determined that the seals in the seal arrangement need to be replaced. In particular, the evaluation device can be designed in such a way that it can detect a break or complete destruction of a shaft seal on the basis of the magnitude of the change in concentration and / or the speed of the change in concentration and emits an alarm signal when a break in the shaft seal is detected.

According to a further preferred embodiment, the evaluation device is designed in such a way that it forms at least one characteristic value derived from the measured value of the concentration sensor and a measured value acquired from the at least one second sensor, in particular a temperature measured value. Such a characteristic value can be a measured concentration value corrected for the influence of temperature, ie a measured concentration value which has been corrected in such a way that a temperature-dependent influence on the measurement result has been eliminated or reduced. On the basis of such a characteristic value, a decision can then be made about the condition of the liquid reservoir; in particular, the characteristic value can be compared with a predetermined limit value for the concentration, and if this limit value is exceeded or undershot, an error signal can be output, which allows maintenance or repair of the Seals signaled.

Thus, the evaluation device can preferably be designed in such a way that, for example, if the temperature is too high and / or too low, which is detected by the second sensor, it suspends a measured value acquisition or measured value evaluation for the concentration. The evaluation device is further preferably designed in such a way that, if a measured value acquisition or measured value evaluation is suspended, it bases further processing on the last measured value recorded before the suspension. That is to say, in such a case, the evaluation device outputs, for example, the last permissible measured value recorded as a concentration value.

According to a further preferred embodiment, the evaluation device can be designed in such a way that the measured values of the concentration sensor are recorded at different points in time and an average value of the recorded measured values is formed as a characteristic value. Short-term fluctuations, which can be attributed to changes in the operating state of the pump unit, for example, can be minimized via the averaging, and only the long-term influences can be taken into account in order to draw conclusions about changes in the liquid reservoir, which make maintenance or repairs to the seals necessary.

The evaluation device can particularly preferably be designed in such a way that it forms a running average value or an average value over a certain period of time as a characteristic value. In this case, the specific time span can be, for example, a specific time span preceding the current point in time. For example, starting from the current point in time, a running average value or a new average value can be formed as a characteristic value at regular intervals for a specific previous period of time. Long-term changes in the characteristic value can thus be recorded while short-term fluctuations are eliminated due to the averaging.

According to a further preferred embodiment of the invention, the evaluation device is designed in such a way that it reads the measured values of the concentration sensor when forming the average value as a function of the measured values recorded by the at least one second sensor and preferably as a function of the temperature measured values recorded by the second sensor and / or in Weighted as a function of time. Thus, for example, measured concentration values in operating states, which allow a more precise measurement of the concentration to be expected, are weighted more heavily in the formation of the average than measured values in operating states of the pump assembly, which allow more imprecise measurements to be expected. The operating states are represented by the measured value recorded by the second sensor. In particular, these can be operating states at different temperatures or different temperatures of the liquid reservoir, which are detected directly or indirectly by the second sensor, as described above. In this way, measured concentration values in temperature ranges that enable more precise concentration detection can be weighted higher than measured concentration values which were recorded at other temperatures. Furthermore, for example, measured values from more recent times can be weighted more heavily than measurements made some time ago. In addition, a temporal acquisition is also possible in such a way that in the event that, for example, a measured value acquisition or measured value evaluation is suspended when the temperature is too high or too low, the last measured value before the suspension is used. At the same time, if necessary, a warning or information signal can be output that a correct measurement could not be carried out for a longer period of time.

The evaluation device can particularly preferably be designed in such a way that measured values, i. H. Concentration measured values that are recorded at a lower temperature are weighted more heavily when forming the average value than measured values that are recorded at a higher temperature. This is done, for example, according to a linear function or an inverse sigmoid function. However, other mathematical functions can also be used to accomplish this. In principle, for example, monotonically decreasing functions can be used in specific temperature intervals, such as the aforementioned linear functions and inverse sigmoid functions. However, it is also possible to use monotonically increasing functions in certain temperature ranges, in particular at very low temperatures that are close to the freezing point. For example, a monotonically falling function can be used in a higher temperature range and a monotonically increasing function in a lower temperature range.

The higher weighting of the measured values recorded at low temperature is particularly preferred when using an ultrasonic sensor, since at low temperatures the changes in concentration lead to a greater change in the speed of sound through the medium, which results in a higher measurement accuracy. At higher temperatures, the speed differences become smaller, so that greater measurement inaccuracies can occur in these areas.

Alternatively or additionally, the evaluation device can have a neural network for evaluating the at least one measured value. Such a neural network has the advantage that a learning evaluation is possible, which continuously adapts to changes in the operating states and environmental conditions, which means the evaluation of the measured value from the concentration sensor can be continuously improved and the accuracy increased.

According to a possible embodiment of the invention, the concentration sensor and the at least one second sensor can be integrated into one sensor module. This applies in particular when the concentration sensor is an ultrasonic sensor and the at least one second sensor is a temperature sensor. In this way, an integrated sensor unit can be created, which as a whole can easily be integrated into a pump unit. In particular, it is also possible to use common electrical connections both for the concentration sensor and the at least one second sensor and, if necessary, to carry out the data transmission via common lines.

According to a further possible embodiment of the invention, there is at least one third sensor which is designed to detect an operating state of the pump assembly. In particular, this at least one third sensor can be designed in such a way that it detects whether the pump assembly is in operation or not. For this purpose, the at least one third sensor can be, for example, a vibration or structure-borne noise sensor. The operating state and, in particular, whether the pump assembly is switched on or off can be very easily detected from a vibration or structure-borne noise signal. The evaluation device is preferably designed in such a way that it evaluates the signal from the concentration sensor only in predetermined operating states, for example when the pump assembly is switched off. This can improve the measurement result. For example, air bubbles can occur in the liquid reservoir during operation, which falsify the measurement result. This can be detected by arranging a third sensor in the manner described so that, for example, a signal from the concentration sensor can only be evaluated in such Operating states take place in which no impairment of the measurement result is to be expected.

As described above, the liquid reservoir is preferably filled with a liquid mixture containing oil or glycol. In particular, the liquid mixture can contain a mixture of glycol and water. The concentration sensor and the evaluation device are preferably designed to detect the concentration of water in the liquid reservoir, so that penetration of the water can be detected and thus a warning message can be generated if the seal facing the pump chamber becomes leaky.

The pump unit is particularly preferably a water pump unit and more preferably a sewage pump unit. Such pump units can be designed as submersible pumps and it is important that the engine compartment in which the dry-running electric drive motor is arranged is reliably sealed.

According to a further possible embodiment, the evaluation device is designed in such a way that, on the basis of the evaluation of the measured values of the concentration sensor, it calculates or predicts a time span until the next maintenance of the pump assembly is due. Maintenance is understood to mean, for example, the replacement of a seal, that is to say a shaft seal. The evaluation device or a control device connected to the evaluation device can estimate the point in time for the next due maintenance. This can be done on the basis of an extrapolation based on the previously recorded measurements of the concentration sensor. For example, starting from essentially constant measured values, there can be a sudden increase, which indicates that the seal must be replaced in the near future. Here can be an exponential There is a tendency which can be taken into account by the evaluation device and a connected control device.

In addition to the pump assembly described, the subject matter of the invention is also a method for detecting a change in concentration in a liquid reservoir in a sealing arrangement in a pump assembly, in which at least one measured value from a concentration sensor arranged on the liquid reservoir is dependent on at least one further parameter of the liquid reservoir and preferably dependent on the temperature or a temperature-dependent parameter of the liquid reservoir is evaluated. In this way, in particular, a temperature influence on the measurement result of a concentration sensor can be compensated. This can be done in the manner described above with reference to the pump assembly. With regard to preferred method steps, the preceding description of the pump assembly is described. The method sequences described there or method sequences resulting from the design of the pump assembly are also preferably the subject of the method according to the invention.

In the method according to the invention, the evaluation of the at least one measured value of the concentration sensor is particularly preferably suspended if the temperature of the liquid reservoir is above an upper limit value or below a lower limit value. In this way it can be ruled out that measured values, which were recorded under ambient conditions which do not allow precise measurement, are taken into account in the recording of the concentration.

In the method according to the invention, an average value is particularly preferably formed during the evaluation from a plurality of measured values from the concentration sensor, the individual Measured values are further preferably weighted differently as a function of a further parameter and preferably as a function of the temperature recorded in each case and / or as a function of time. In particular, measured values that were recorded at a lower temperature, as described above with reference to the pump assembly, can be weighted higher.

Fig. 1

eine perspektivische Ansicht eines erfindungsgemäßen Pumpenaggregates,

Fig. 2

eine Schnittansicht des Antriebsmotors des Pumpenaggregates gemäß Fig. 1,

Fig. 3

eine vergrößerte Schnittansicht der Dichtungsanordnung an dem Antriebsmotor gemäß Fig. 2,

Fig. 4

schematisch die Konzentrationsmessung mittels Ultraschall,

Fig. 5

die Schallgeschwindigkeit in der Flüssigkeitsvorlage in Abhängigkeit der Temperatur für verschiedene Konzentrationen, und

Fig. 6

schematisch den Ablauf einer bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens.

The invention is described below by way of example with reference to the accompanying figures. In this shows:

Fig. 1

a perspective view of a pump unit according to the invention,

Fig. 2

a sectional view of the drive motor of the pump assembly according to Fig. 1 ,

Fig. 3

an enlarged sectional view of the seal arrangement on the drive motor according to FIG Fig. 2 ,

Fig. 4

schematically the concentration measurement by means of ultrasound,

Fig. 5

the speed of sound in the liquid reservoir as a function of the temperature for different concentrations, and

Fig. 6

schematically the sequence of a preferred embodiment of the method according to the invention.

The pump unit according to the invention, which is exemplified in Figures 1 and 2 is shown, is designed as a submersible pump unit. The pump unit has an electrical one in a known manner Drive motor 2 with an attached pump housing 4. The pump housing 4 has an inlet opening 6 and a radial pressure port 8 on its underside. At the axial end of the drive motor 2 facing away from the pump housing 4, it has a terminal box or an electronics housing 10 in which control electronics for the drive motor 2 can be arranged and / or the electrical connection to a connection line 12 for the power supply can be established can.

The inside of the pump housing 4 contains, in a known manner, a pump space in which an impeller (not shown here) rotates. The impeller is non-rotatably connected to the drive shaft or shaft 14 of the drive motor 6. In the drive motor 2, the shaft 14 is non-rotatably connected to the rotor 16 of the drive motor, which rotates in a known manner inside the stator 18. The drive motor 6 is designed as a dry-running motor, ie the interior of the drive motor 2 is completely sealed from the pump chamber in the interior of the pump housing 4, for which purpose the shaft 14 is passed through a sealing arrangement 20. The sealing arrangement 20 has a liquid reservoir 22 inside a chamber delimited by a sealing housing 24. The sealing arrangement 20 also has two seals 26 and 28, which are designed as shaft seals and through which the shaft 14 is passed in a sealing manner. The seal 26 forms a first seal which faces the pump housing 4, while the seal 28 forms a second seal which faces the drive motor 2. The liquid reservoir 22 is located between the first seal 26 and the second seal 28. If the first seal 26 should now fail, liquid penetrates from the pump housing 4 into the interior of the liquid reservoir 22, which can be detected. As expected, the first seal 26 will wear out sooner than the second seal 28, as a result of which the wear of the seal can be recognized before liquid from the liquid reservoir 22 into the interior of the drive motor 2 penetrates. The structure of the liquid reservoir 22 is explained in more detail below with reference to FIG Fig. 3 described.

The liquid reservoir 22 can preferably be filled with a liquid mixture which contains oil or glycol, in particular with a glycol-water mixture. In addition to glycol and water, the mixture can also contain other additives or additives. If water penetrates into the liquid reservoir 22 from the pump space inside the pump housing 4 through the first seal 26, the glycol-water concentration in the liquid reservoir 22 changes is used. The concentration sensor 30 extends into the interior of the chamber in which the liquid reservoir 22 is located. In addition, a second sensor 32 is arranged on the seal housing 24, which in this case is designed as a temperature sensor. The second sensor 32 can, however, also be designed as a combined sensor which detects several parameters, for example temperature and pressure and / or vibrations. So, as in Figure 3 shown, a vibration sensor 33 can be integrated as a third sensor in the second sensor. The vibration sensor 33 is used to detect whether the pump assembly is in operation or not. Both the concentration sensor 30 and the second sensor 32 are connected to an evaluation device 34. The output signals of the vibration sensor 33 are also evaluated by the evaluation device 34 in order, for example, to suspend the evaluation of the other sensor in the event of excessive vibrations. The evaluation device 34 can be part of control or regulation electronics 36 in the interior of the electronics housing 10 (see FIG Fig. 2 ), which controls the drive motor 2.

In this exemplary embodiment, the concentration sensor 30 is designed as an ultrasonic sensor, as it is based on Fig. 4 described will. The concentration sensor 30 has a transmitting / receiving unit 38 which transmits an ultrasonic signal into the interior of the liquid reservoir 22 to an opposite wall 40. The signal is reflected on the wall 40 and sent back to the transceiver unit 38, at which the signal is received again. The transmitting / receiving unit 38 is connected to the evaluation device 34, which can detect the signal transit time of the ultrasonic signal between the transmitting / receiving unit 38 and the wall 40. The speed of sound of the liquid reservoir 22 changes as a function of the concentration, so that changes in the concentration can be detected by the evaluation unit 34 from the transit time and thus the speed of the signal in the liquid reservoir 22. The transmitting / receiving unit 38 can be designed as a piezo element, for example.

In Fig. 5 signal curves for the signal speed within the liquid reservoir 22 for four different concentrations conc0, concl, conc2 and conc3 are shown. In Fig. 5 the speed u plotted against the temperature T. It can be seen that the speed differences between the individual concentrations decrease with increasing temperature T. I. E. the measuring accuracy of the concentration decreases with increasing temperature. Exact measurement is no longer possible above a temperature limit value Tg. Therefore, it is provided according to the invention that the evaluation device 34 preferably suspends the evaluation of the measurement result of the concentration sensor 30 when the temperature Tg is exceeded. A sewage pump is usually not operated continuously but at intervals. The temperature rises during operation. When the pump is then switched off again, the temperature drops again, so that it may regularly occur during operation that the temperature limit value Tg is exceeded, but then falls below it again. The concentration measurement or evaluation of the measured value of the concentration sensor 30 is then carried out by the evaluation device 34 only carried out for measurements at temperatures below the temperature limit value Tg.

The determination of the concentration in the liquid reservoir 22 can be carried out by the evaluation device 34, for example, on the basis of FIG Fig. 6 described manner. _{A current concentration C i} is recorded by the concentration sensor 30 and a current temperature T _{i is} recorded by the temperature sensor 32 as input variables. In step S1 it is checked whether the current temperature value T is below a limit value T _thres (corresponds to T _g ). If this is the case (Y), in step S2 a corrected concentration _{value C out is determined} as a function of the measured concentration values C _i , the measured temperature values T _i and the time t _i . For example, the concentration C _{out can be determined} as a weighted average value of a multiplicity of concentrations C _i measured over a longer period of time, in particular as a running average. The weighting can be time-dependent and / or temperature-dependent. In particular, the weighting is preferably carried out in such a way that measurements at low temperatures are weighted more heavily than measurements at higher temperatures. This can take place according to a linear function or also an inverse sigmoid function or other suitable mathematical function.

If it should be determined in step S1 that the temperature T _{i is} above the set temperature _{limit value} T thres (N), it is checked in step S3 whether the period t since the last determination of a concentration _{value C out is} less than a predetermined interval t _interval . If this is the case (Y), C _{out is set} to the last determined value in step A1. If it is determined in step S3 that the time interval t is equal to or greater than the specified interval t _interval (N), the concentration _{value C out is set} to the last determined value in step A2 and a warning message is issued at the same time that no current measurement or concentration determination is possible.

Alternatively, the determination of the concentration C _out (estimated or corrected concentration) based on the temperature T _i and the measured measured concentration value C _{i could} also take place in another way, for example using a neural network. Such a neural network could adapt to changes in the ambient and operating conditions and adapt the correction of _{the measured concentration value C i} as a function of the temperature in a learning manner.

Other algorithms or methods can also be used _{to correct or adapt the measured concentration values C i as a function of} temperature in order to reduce or eliminate the temperature influence from the concentration measurement.

List of reference symbols

2

- drive motor

4th

- pump housing

6th

- Entrance opening

8th

- pressure port

10

- electronics housing

12th

- connecting cable

14th

- Wave

16

- rotor

18th

- stator

20th

- Seal arrangement

22nd

- Liquid reserve

24

- Seal housing

26th

- first seal

28

- second seal

30th

- concentration sensor

32

- second sensor / temperature sensor

33

third sensor / vibration sensor

34

- Evaluation device

36

- control electronics

38

- Transmitter / receiver unit

40

- wall

Tg, Tthres

- temperature limit

t

- Time

T

- temperature

C.

- concentration

Claims (23)

1. A pump assembly with an electrical drive motor (2) and with at least one impeller which is connected to the drive motor (2) via a shaft (14), wherein the shaft extends between the drive motor (2) and the impeller through at least one seal arrangement (20) with a fluid reservoir (22),
   characterised in that
   at least one concentration sensor (30) for detecting a concentration change in the fluid reservoir (22) and at least one second sensor (32) for detecting at least one further parameter (22) of the fluid reservoir (22) are arranged on the fluid reservoir (22), said sensors being connected to an evaluation device (34), and that the evaluation device (34) is designed in a manner such that it carries out an evaluation of at least one reading of the concentration sensor (30) whilst taking into account at least one reading which is detected by the second sensor (32).
2. A pump assembly according to claim 1, characterised in that the at least one second sensor is a temperature sensor (32) or a sensor which detects at least one temperature-dependent parameter.
3. A pump assembly according to claim 1 or 2, characterised in that the evaluation device (34) is designed in a manner such that it carries out an evaluation of at least one reading of the concentration sensor (30) whilst taking into account at least one temperature reading or temperature-dependent parameter, which is detected by the second sensor (32).
4. A pump assembly according to one of the preceding claims, characterised in that the concentration sensor (30) is an ultrasound sensor, an optical sensor or a capacitive sensor.
5. A pump assembly according to one of the preceding claims, characterised in that the evaluation device (34) is designed in a manner such that it only carries out an evaluation of a reading of the concentration sensor (30) when the reading which is detected by the at least one second sensor (32) and in particular a temperature reading which is detected by the second sensor lies below a defined maximal limit value.
6. A pump assembly according to one of the preceding claims, characterised in that the evaluation device (34) is designed in a manner such that it only carries out an evaluation of a reading of the concentration sensor (30) when the reading which is detected by the at least one second sensor (32) and in particular a temperature reading which is detected by the second sensor lies above a defined minimal limit value.
7. A pump assembly according to one of the preceding claims, characterised in that the evaluation device (34) is designed in a manner such that given the skipping of a reading acquisition or reading evaluation, it takes the last reading which was detected before the skipping as a basis for the further processing.
8. A pump assembly according to one of the preceding claims, characterised in that the evaluation device (34) is designed in a manner such that it outputs an alarm signal on the basis of a reading which is detected by the concentration sensor (32), if this at least one reading or a characteristic value which is derived from the reading reaches a predefined concentration limit value.
9. A pump assembly according to one of the preceding claims, characterised in that the evaluation device (34) is designed in a manner such that it forms at least one characteristic value which is derived from the reading of the concentration sensor (30) and from a reading, in particular a temperature reading, which is detected by the at least one second sensor (32).
10. A pump assembly according to one of the preceding claims, characterised in that the evaluation device (34) is designed in a manner such that it detects readings of the concentration sensor (30) at different points in time and forms an average value of the detected readings as a characteristic value.
11. A pump assembly according to claim 10, characterised in that the evaluation device (34) is designed in a manner such that it forms a rolling average value or an average value over a certain time span, as a characteristic value.
12. A pump assembly according to claim 10 or 11, characterised in that the evaluation device (34) is designed in a manner such that on forming the average value, it weights the readings of the concentration sensor (30) in dependence on the readings which are detected by the second sensor (32) and preferably in dependence on the temperature readings which are detected by the at least one second sensor (32) and/or in dependence on the time.
13. A pump assembly according to claim 12, characterised in that the evaluation device (34) is designed in a manner such that on forming the average value, readings which are detected at a lower temperature are weighted higher than readings which are detected at a higher temperature, wherein this is preferably effected according to a linear function or an inverse Sigmoid function.
14. A pump assembly according to one of the preceding claims, characterised in that the evaluation device (34) comprises a neuronal network for evaluating the at least one reading.
15. A pump assembly according to one of the preceding claims, characterised in that the concentration sensor (30) and the at least one second sensor (32) are integrated in a sensor construction unit.
16. A pump assembly according to one of the preceding claims, characterised by at least one third sensor (33) which is designed to detect an operating state of the pump assembly.
17. A pump assembly according to one of the preceding claims, characterised in that the fluid reservoir (22) is filled with a fluid mixture which contains oil or glycol.
18. A pump assembly according to one of the preceding claims, characterised in that the concentration sensor (30) and the evaluation device (34) are designed for detecting the concentration of water in the fluid reservoir.
19. A pump assembly according to one of the preceding claims, characterised in that the pump assembly is a waste water pump assembly.
20. A pump assembly according to one of the preceding claims, characterised in that the evaluation device (34) is designed in a manner such that it computes or predicts a time interval until the next due maintenance of the pump assembly on the basis of the evaluation of the readings of the concentration sensor (30).
21. A method for detecting a concentration change in a fluid reservoir (22) in a seal arrangement (20) in a pump assembly, concerning which at least one reading of a concentration sensor (30) which is arranged on the fluid reservoir (22) is evaluated in dependence on at least one further parameter of the fluid reservoir and preferably in dependence on the temperature of or on a temperature-dependent parameter of the fluid reservoir (22).
22. A method according to claim 21, characterised in that the evaluation of the at least one reading is skipped if the temperature lies above an upper limit value or below a lower limit value.
23. A method according to claim 21 or 22, characterised in that on evaluation, an average value is formed from a plurality of readings of the concentration sensor (30), wherein the individual readings are weighted differently depending on a further parameter and preferably in dependence on the respectively detected temperature and/or in dependence on time.

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