Pump assembly having an impeller, a motor, and a shaft, with the shaft passing from the motor to the impeller through a fluid reservoir and a seal arrangemnet with a tration

Abstract

A pump assembly includes an electrical drive motor (2) and an impeller which is connected to the drive motor (2) via a shaft (14). The shaft extends between the drive motor (2) and the impeller, through a seal arrangement with a fluid reservoir (22). A method is provided for detecting a concentration change in a fluid reservoir in the seal arrangement in the pump assembly. A concentration sensor (30) detects a concentration change in the fluid reservoir (22), and a second sensor (32) detects at least one further parameter of the fluid reservoir (22). The sensors are arranged on the fluid reservoir (22). The sensors are connected to an evaluation device (22). The evaluation device (34) is configured to carry out an evaluation of at least one reading of the concentration sensor (30), taking into account at least one reading which is detected by the second sensor (32).

Claims

1. A pump assembly comprising: an electrical drive motor; at least one seal arrangement with a fluid reservoir; a shaft; at least one impeller connected to the drive motor via the shaft, wherein the shaft extends between the drive motor and the impeller, through the at least one seal arrangement with the fluid reservoir; a concentration sensor for detecting a fluid concentration change in the fluid reservoir, the concentration sensor being arranged in operative communication with the fluid reservoir; a second sensor for detecting a further parameter of the fluid reservoir, the second sensor being arranged in operative communication with the fluid reservoir; and an evaluation device connected to each of the concentration sensor and the second sensor, the evaluation device being configured to carry out an evaluation of at least one reading of the concentration sensor taking into account at least one reading by the second sensor.

2. A pump assembly according to claim 1, wherein the second sensor is a temperature sensor or a temperature-dependent parameter sensor which detects at least one temperature-dependent parameter.

3. A pump assembly according to claim 1, wherein the evaluation device is configured to carry out an evaluation of the at least one reading of the concentration sensor, taking into account the at least one temperature reading or temperature-dependent parameter reading, which is detected by the second sensor.

4. A pump assembly according to claim 1, wherein the concentration sensor comprises an ultrasound sensor, an optical sensor or a capacitive sensor.

5. A pump assembly according to claim 1, wherein the evaluation device is configured to only carry out an evaluation of the at least one reading of the concentration sensor when the at least one reading which is detected by the second sensor lies below a defined maximal limit value.

6. A pump assembly according to claim 1, wherein the evaluation device is configured to only carry out an evaluation of a reading of the concentration sensor when the reading which is detected by the second sensor lies above a defined minimal limit value.

7. A pump assembly according to claim 1, wherein the evaluation device is configured such that with a skipping of a reading acquisition or reading evaluation, the evaluation device takes a last reading, which was detected before the skipping, as a basis for further processing.

8. A pump assembly according to claim 1, wherein the evaluation device is configured to output an alarm signal based of the at least one reading which is detected by the concentration sensor, if the 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 claim 1, wherein the evaluation device is configured to form at least one characteristic value which is derived from the at least one reading of the concentration sensor and from at least one reading detected by the second sensor.

10. A pump assembly according to claim 1, wherein the evaluation device is configured to detect readings of the concentration sensor at different points in time and form an average value of the detected readings as a characteristic value.

11. A pump assembly according to claim 10, wherein the evaluation device is configured to 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, wherein the evaluation device is configured upon forming the average value, to weight readings of the concentration sensor in dependence on the readings which are detected by the second sensor and/or in dependence on a time.

13. A pump assembly according to claim 12, wherein the evaluation device is configured upon forming the average value, to weight readings which are detected at a lower temperature higher than readings which are detected at a higher temperature and to effect the weighting according to a linear function or an inverse Sigmoid function.

14. A pump assembly according to claim 1, wherein the evaluation device comprises a neuronal network for evaluating the at least one reading.

15. A pump assembly according to claim 1, wherein the concentration sensor and the second sensor are integrated in a sensor construction unit.

16. A pump assembly according to claim 1, further comprising a third sensor which is configured to detect an operating condition of the pump assembly.

17. A pump assembly according to claim 1, wherein the fluid reservoir is filled with a fluid mixture comprising oil or glycol.

18. A pump assembly according to claim 1, wherein the concentration sensor and the evaluation device are configured for detecting the concentration of water in the fluid reservoir.

19. A pump assembly according to claim 1, wherein the pump assembly is a waste water pump assembly.

20. A pump assembly according to claim 1, wherein the evaluation device is configured to compute or predict a time interval until a next due maintenance of the pump assembly based on the evaluation of the readings of the concentration sensor.

21. A method for detecting a concentration change in a fluid reservoir in a seal arrangement in a pump assembly comprising an electrical drive motor, the seal arrangement with the fluid reservoir, a shaft, at least one impeller connected to the drive motor via the shaft, wherein the shaft extends between the drive motor and the impeller, through the seal arrangement with the fluid reservoir, the method comprising the steps of: providing a concentration sensor, for detecting a fluid concentration change in the fluid reservoir, arranged in operative communication with the fluid reservoir; providing a second sensor, for detecting a further parameter of the fluid reservoir, arranged in operative communication with the fluid reservoir; connecting an evaluation device to each of the concentration sensor and the second sensor, wherein the evaluation device being configured to carry out an evaluation of at least one reading of the concentration sensor taking into account at least one reading by the second sensor; and evaluating, with the evaluation device, a reading of the concentration sensor in dependence on a reading of the second sensor.

22. A method according to claim 21, wherein: the second sensor is a temperature sensor or a temperature-dependent parameter sensor which detects at least one temperature-dependent parameter; and 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, wherein: upon evaluation, an average value is formed from a plurality of readings of the concentration sensor; individual readings are weighted differently depending on a reading of the second sensor and/or in dependence on time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a perspective view of a pump assembly according to the invention;

(3) FIG. 2 is a sectioned view of the drive motor of the pump assembly according to FIG. 1;

(4) FIG. 3 is an enlarged sectioned view of the seal arrangement on the drive motor according to FIG. 2;

(5) FIG. 4 is schematic view showing the concentration measurement by way of ultrasound;

(6) FIG. 5 is a graph showing the speed of sound in the fluid reservoir in dependence on the temperature, for different concentrations; and

(7) FIG. 6 is a schematic view showing the course of preferred embodiment of the method according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

(8) Referring to the drawings, the pump assembly according to the invention which is represented by way of example in FIGS. 1 and 2 is configured as a submersible pump assembly. The pump assembly in the known manner comprises an electrical drive motor 2 with an applied or attached pump casing 4. The pump casing 4 at its lower side comprises an inlet opening 6 as well as a radial delivery branch 8 which is to say delivery pipe connection. The drive motor 2 at its axial end which is away from the pump casing 4 comprises a terminal box or an electronics housing 10, in which control and regulation electronics for the drive motor 2 can be arranged and/or the electrical connection to a connection lead 12 for the energy supply can be created.

(9) The pump casing 4 in its inside and in the usual manner comprises a pump chamber, in which an impeller (not shown here) rotates. The impeller is connected to the drive shaft or shaft 14 of the drive motor 2 in a rotationally fixed manner. The shaft 14 is connected to the rotor 16 of the drive motor 2 in a rotationally fixed manner in the drive motor 2, said rotor rotating in the inside of the stator 18 in the known manner. The drive motor 2 is configured as dry-running motor, i.e. the interior of the drive motor 2 is completely sealed with respect to the pump chamber in the inside of the pump casing 4, for which the shaft 14 is led through a seal arrangement 20. The seal or sealing arrangement 20 comprises a fluid reservoir 22 in the inside of a chamber which is delimited by a seal housing 24. The seal arrangement 20 moreover comprises two seals 26 and 28 which are configured as shaft seals and through which the shaft 14 is sealingly led. The seal 26 forms a first seal which faces the pump casing 4, whereas the seal 28 forms a second seal which faces the drive motor 2. The fluid reservoir 22 is situated between the first seal 26 and the second seal 28. If the first seal 26 were now to fail, then fluid from the pump casing 4 would penetrate into the inside of the fluid reservoir 22, which can be detected. According to expectations, the first seal 26 would tend to wear more rapidly than the second seal 28, by which means the wearing of the seal can be recognized before fluid from the fluid reservoir 22 penetrates into the inside of the drive motor 2. The construction of the fluid reservoir 22 is hereinafter described in more detail by way of FIG. 3.

(10) The fluid reservoir 22 can preferably be filled with a fluid mixture which contains oil or glycol, in particular with a glycol-water mixture. Here, the mixture can yet comprise further additives, apart from glycol and water. If water from the pump chamber in the inside of the pump casing 4 penetrates through the first seal 26 into the fluid reservoir 22, then the glycol-water concentration in the fluid reservoir 22 changes. This is detected by a concentration sensor 30 which is inserted into the seal housing 24 of the seal arrangement 20. The concentration sensor 30 extends into the inside of the chamber, in which the fluid reservoir 22 is located. A second sensor 32 which in this case is configured as a temperature sensor is additionally arranged on the seal housing 24. However, the second sensor 32 can also be configured as a combined sensor which detects several parameters, for example temperature and pressure and/or vibrations. As represented in FIG. 3, a vibration sensor 33 as a third sensor can thus be integrated in the second sensor. The vibration sensor 33 serves for recognizing whether the pump assembly is in operation or not. The concentration sensor 30 as well as the second sensor 32 is connected to an evaluation device 34. The evaluation device 34 comprises one or more processors and associated memory. The output signals of the vibration sensor 33 are also evaluated by the evaluation device 34, in order for example to skip the evaluation of the other sensor given vibrations which are too large. The evaluation device 34 can be part of control and regulation electronics 36 in the inside of the electronics housing 10 (see FIG. 2), said electronics controlling the drive motor 2.

(11) In this embodiment example, the concentration sensor 30 is configured as an ultrasound sensor as is described by way of FIG. 4. The concentration sensor 30 comprises an emitting/receiving unit 38 which emits an ultrasound signal into the inside of the fluid reservoir 22 to an opposite wall 40. The signal is reflected at the wall 40 and is sent back to the emitting/receiving unit 38, at which the signal is received again. The emitting/receiving unit 38 is connected to the evaluation device 34 which can detect the signal propagation time of the ultrasound signal between the emitting/receiving unit 38 and the wall 40. The speed of sound of the fluid reservoir 22 changes depending on the concentration, so that changes of the concentration can be detected by the evaluation unit 34 from the propagation time and thus from the speed of the signal in the fluid reservoir 22. The emitting/receiving unit 38 can be configured for example as a piezoelement.

(12) Signal courses for the signal speed within the fluid reservoir 22 are represented in FIG. 5 for four different concentrations conc0, conc1, conc2 and conc3. Here in FIG. 5, the speed u is plotted against temperature T. One can recognize that the speed differences between the individual concentrations reduce with an increasing temperature T. I.e. the measuring accuracy of the concentration decreases with an increasing temperature. A precise measurement is no longer possible from a temperature limit value T.sub.g. For this reason, according to the invention, one envisages the evaluation device 34 preferably skipping the evaluation of the measuring result of the concentration sensor 30 on exceeding the temperature T.sub.g. As a rule, a waste water pump is not operated in a continuous manner, but in intervals. The temperature increases on operation. The temperature reduces again when the pump is then switched off again, so that on operation it is possibly regularly the case that the temperature limit value T.sub.g is exceeded, but is subsequently fallen short of. The concentration measurement or evaluation of the reading of the concentration sensor 30 is then only carried out by the evaluation device 34 for measurements at temperatures below the temperature limit value T.sub.g.

(13) The evaluation of the concentration in the fluid reservoir 22 can be effected by the evaluation device 34 for example in the manner which is described by way of FIG. 6. A current concentration C.sub.i is detected by the concentration sensor 30, as well as a current temperature T.sub.i by the temperature sensor 32, as input values. In step S1, it is examined as to whether the current temperature value T lies below a limit value T.sub.thres (corresponds to T.sub.g). In this is the case (Y), then a corrected concentration value C.sub.out as a function of the measured concentration values C.sub.i, of the measured temperature values T.sub.i as well as of the time ti is determined in step S2. Thus for example the concentration C.sub.out can be determined as a weighted average value of a multitude of concentrations C.sub.i which are measured of a longer period of time, in particular as a rolling average. The weighting can be effected in a time-dependent and/or temperature-dependent manner. In particular, the weighting is preferably effected such that measurements at lower temperatures are weighted higher than measurements at higher temperatures. This can be effected according to a linear function or also a reverse Sigmoid function or other suitable mathematic functions.

(14) If it should be ascertained in Step S1 that the temperature T.sub.i lies above the set temperature limit value T.sub.thresh (N), then in step S3 it is examined as to whether the time period t since the last evaluation of the concentration value C.sub.out is smaller than a defined interval t.sub.interval. If this is the case (Y), then in Step A1 C.sub.out is set to the last determined value. If it is ascertained in Step S3 that the time interval t is the same or larger than the predefined interval t.sub.interval (N), then in step A2 the concentration value C.sub.out is set the last determined value and a warning notice to the effect that no current (present) measurement or determining of the concentration is possible is simultaneously issued.

(15) The determining of the concentration C.sub.out (estimated or corrected concentration) on the basis of the temperature T.sub.i and the measured concentration value C.sub.i can also be effected in a different manner, for example amid the use of a neuronal network. Such a neuronal network could adapt to changes of the ambient conditions and operating conditions, and in a learning manner adapt the correction of the concentration readings C.sub.i in dependence on the temperature.

(16) Other algorithms or methods can also be used, in order to correct or adapt the concentration readings C.sub.i in a temperature-dependent manner, in order to reduce or eliminate the influence of the temperature upon the concentration measurement.

(17) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

APPENDIX

List of Reference Designations

(18) 2—drive motor 4—pump casing 6—inlet opening 8—delivery pipe connection 10—electronics housing value 12—connection conduit 14—shaft 16—rotor 18—stator 20—seal arrangement 22≤fluid reservoir 24—seal housing 26—first seal 28—second seal 30—concentration sensor 32—second sensor/temperature sensor 33—third sensor/vibration sensor 34—evaluation device 36—control electronics 38—emitting/receiving unit 40—wall T.sub.g, T.sub.thres—temperature limit t—time T—temperature C—concentration