EP3067564B1 - Circulation pump - Google Patents

Description

The invention relates to a circulating pump unit and in particular a heating circulating pump unit.

Such Umwälzpumpenaggregate are usually formed with wet-running electric drive motors, in which the plain bearings for the rotor by the pumped liquid, usually water, are lubricated. Therefore, prolonged dry running of the bearings can lead to damage and should therefore be avoided.

It is known in the art to design the control electronics of such circulating pump units so that they can detect a dry run and the pump unit can shut down in good time. Additional sensors should be avoided for cost reasons while possible.

Out EP 0 967 475 A1 For example, a method is known for determining the viscosity of a fluid delivered by a pump, such as a blood pump. The viscosity is determined from measured variables of the pump.

It is an object of the invention to improve a circulation pump unit in such a way that a dry run can be detected in a simple manner without additional sensors.

This object is achieved by a circulating pump unit having the features specified in claim 1 and a method for operating a circulating pump unit with the features specified in claim 14. Preferred embodiments will become apparent from the appended subclaims, the following description and the attached figures.

The circulating pump unit according to the invention has an electric drive motor, which is connected to at least one impeller, so that it can be driven in rotation by the electric drive motor. The electric drive motor is preferably designed as a canned motor, that is, as a wet-running electric drive motor. More preferably, the drive motor to a rotor which is mounted in plain bearings, which are lubricated by a pumped by the circulation pumping liquid. Preferably, the circulation pump unit is designed to convey water, so that the bearings are lubricated with water. The circulating pump unit also has an electronic control device, which controls or regulates the drive motor. Such a control device may in particular include a frequency converter, via which the rotational speed and preferably the direction of rotation of the drive motor can be adjusted or regulated. The electronic control device is preferably arranged in an electronics housing directly on the drive motor or a stator housing of the drive motor.

According to the invention, the control device has at least one first fluid-detection function, which serves to detect at least one property of the fluid which is located in the impeller or is conveyed by the impeller. According to this first fluid recognition function, the control device controls the drive motor in such a way that it rotates successively with two different rotational speeds predetermined by the control device or in different rotational directions. In each case, the electrical power consumption is detected by the control device. Subsequently, based on the recorded power consumption at the different rotational speeds or directions of rotation by the control device, an evaluation is carried out in order to detect the at least one property of the fluid in the impeller. The power consumption and in particular a development The power consumption may be different for different fluids, so that it can be concluded by evaluating the power consumption on certain properties or certain fluids. In particular, it is possible to distinguish whether there is a liquid or a gas, such as air, in the impeller. The use of at least two different speeds or directions of rotation has the advantage that a more reliable detection of the property of the fluid to be determined is possible.

The plurality of different speeds, that is, the at least two different speeds, or the different directions of rotation are preferably applied according to the first fluid detection function immediately after one another, since it can be assumed that the hydraulic state of the system, in which the Umwälzpumpenaggregat is integrated , has not changed in essence.

If only a power consumption in an operating condition would be taken into account, as for example in the DE 101 01 099 A1 disclosed, there would be a risk of misinterpretation. For example, during the initial startup of such Umwälzpumpenaggregate with plain bearings, these plain bearings can be lubricated for the first use with a higher viscosity material such as glycerol, so that at the first startup higher friction and thus a higher power consumption than in normal operation. Conversely, in a dry run, as long as the bearings are lubricated normally, the power consumption is lower, for example, than when the impeller promotes a liquid. Therefore, during initial commissioning, the dry running can not be detected reliably when taking into account the power consumption with only one rotational speed or direction of rotation. However, if the power inputs are detected at different speeds or directions of rotation, further information may be obtained which is sufficient, different characteristics, especially with regard to the viscosity of the fluid. In the case of different viscosities or different fluids, for example, there are different developments of the friction during the acceleration, and thus the power consumption, which can be detected and distinguished by the control device. So it is possible to consider not only two different speeds, but to select a defined speed curve, for example, a ramp-shaped acceleration and during this continuously or in several steps to record the power consumption and evaluate. For this purpose, the control device can be designed accordingly.

The control device is therefore further preferably designed such that the first fluid-detection function at a start-up of Umwälzpumpenaggregates after a standstill, especially during the initial startup of Umwälzpumpenaggregates is executed. Also, a state in which, as described, the bearings are not yet lubricated with the liquid promoted in operation, but optionally with another substance, such as glycerol, can be detected by applying the inventive first fluid detection function of the control device.

According to the invention, the control device is designed such that it compares the detected electrical power consumption at the different rotational speeds or in the different directions of rotation and a condition of the fluid in the impeller at a ratio of the detected power consumption, that is, a ratio of the power consumption to each other recognizes. Furthermore, the control device is designed such that it by evaluating the detected electrical power consumption and in particular to the ratio of Power consumption detects if a liquid is in the impeller. So can the normal operating condition be distinguished from dry running. In particular, as stated above, a dry run can be reliably detected even at initial startup of the circulating pump unit. For example, if the impeller is driven in two directions of rotation and there is dry running, that is, the impeller rotates in air, the power consumption will be substantially equal in both directions of rotation, so that the ratio of the power consumptions to one another is substantially equal to one. However, if the impeller is running in a liquid, for example water, the power consumption will be higher in one direction of rotation because it has a higher efficiency in a preferred direction of rotation used in normal operation. Thus, the ratio of the detected power consumptions to each other is substantially unequal to 1, whereby it can be seen that the fluid in the impeller is a liquid and not a gas. In this respect, different properties of the fluid can be distinguished, and particularly preferably the dry run can be recognized by the control device. However, it is also possible to differentiate other fluids or liquids, for example, in terms of viscosity from each other. For this purpose, if appropriate, the temperature of the fluid can also be detected by the control device via a sensor and used for the evaluation.

If the power consumption is detected at two or more different speeds, a different ratio of power consumption depending on the delivered fluids, and in particular depending on their viscosities can be adjusted due to different speed developments, so that the ratio of the power consumption differences of the fluids are recognized can.

According to a further preferred embodiment of the invention, the control device is designed such that the first fluid detection function is used for a first commissioning of a circulating pump unit until the first time a liquid is detected in the impeller by the evaluation of the detected electrical power consumption.

According to a particular embodiment of the invention, the control device may be designed such that the fluid detection function is used only during the initial startup until the first time a liquid is detected in the circulating pump unit. The control device can then be designed so that it no longer applies the first fluid detection function thereafter. Alternatively, the control device may be configured such that the first fluid recognition function is again used, for example, even after a longer standstill of the pump unit, which is longer than a predetermined period of time.

Particularly preferably, the control device is designed such that, if the recorded power consumption are the same in both directions of rotation or both speeds, it outputs an error message and / or blocks further operation of the circulating pump unit. As described above, substantially equal power inputs in both directions of rotation are indicative of dry running. Therefore, it is preferable that, when such a condition is detected by the control means, the control means prohibits the operation of the circulation pump assembly to prevent damage to the bearings. Alternatively or simultaneously, an error message, for example on a display of the control device, is preferably output in order to signal the operator to this state, so that the operator can remedy the situation.

More preferably, the control device is designed such that the first fluid detection function described repeatedly executed is, as long as the evaluation of the detected electrical power consumption shows that there is no liquid in the impeller, that is, a dry run is present. If such a condition is detected, for example, after a predetermined pause, the fluid detection function can be restarted to automatically check whether liquid has since entered the circulation pump unit. Such a configuration of the control device simplifies the commissioning of the circulating pump unit since the circulating pump unit does not have to be restarted, but automatically recognizes the condition in which it can start its normal operation.

According to a further preferred embodiment of the invention, the control device may have a second fluid-detection function, in which the control device during operation, that is, in particular during normal operation of the Umwälzpumpenaggregates, detects the power consumption of the drive motor and compared with at least one predetermined lower limit. In normal operation, this second fluid-detection function thus preferably takes place at the operating speed of the drive motor, which results from the demands placed on the circulating pump unit in the respective operating state, in particular hydraulic requirements. That is, the controller preferably does not select a specific speed for the second fluid detection function, but performs this second fluid detection function during operation at the normal operating speed of the circulating pump unit. This takes place during operation continuously or at intervals. The second fluid detection function may also preferably serve to detect a dry run. If the impeller promotes air instead of a liquid, the hydraulic resistance is lower, so that the power consumption of the drive motor decreases, so this preferably falls below the predetermined lower limit. If this is the case, then a dry run can be detected by the control device.

The control device is preferably further configured such that the second fluid recognition function is used after a predetermined property of the fluid in the impeller and in particular a presence of a fluid in the impeller has been detected by means of the first fluid recognition function. Thus, the first fluid detection function, as described above, for example, serve to avoid dry running during startup and in particular the initial startup of Umwälzpumpenaggregates, while after successful initial startup then the second fluid detection function is used in further operation, in particular then later recognize a dry run and the pump unit can be switched off if necessary. Thus, the first fluid detection function is preferably used only to detect a liquid in the impeller for the first time.

The lower limit in the second fluid recognition function is more preferably a limit curve having a function of the rotational speed of the drive motor. That is, for each speed of the drive motor, there is a corresponding lower limit, so that during operation of the Umwälzpumpenaggregates at each operating speed, a comparison with the lower limit is possible. This lower limit is stored in the control device.

The control device is further preferably designed such that when the lower limit for the power consumption falls below the control device outputs an error message and / or stops the drive motor. Since a dry run is detected in particular when falling below the lower limit, it is desirable to suspend the operation of the drive motor in this state to damage to avoid the bearings. Preferably, an error message is simultaneously output, for example via a display, to the control device in order to signal an error to an operator.

According to a particular embodiment of the invention, the control device can also be designed such that it increases the speed and / or the power of the drive motor for the second fluid detection function at least at intervals, in particular increases the power and / or the rotational speed to a possible maximum value , This can be done either at fixed time intervals or else the control device can make such a speed or power increase only in certain operating states of the circulating pump unit in order to reliably detect a fluid and in particular dry running. Particularly at low speeds, the described lower limit, below which the power consumption suggests dry running, is very close to the power consumption occurring during normal operation, so that dry running in this operating state may not be reliably detected. Therefore, the control device can be designed such that, upon detection of such an operating state, in which the power consumption is close to the lower limit, it causes a speed increase or increase of power, and then make another check for a possible dry run. In high speed ranges, the lower limit is farther away from the power consumption occurring during normal operation. Thus, the controller can increase the speed for such a review in a short time.

According to a further preferred embodiment, the control device is designed such that it stops the drive motor falls below the lower limit and after a predetermined period of time, the second fluid detection function under commissioning the drive motor performs again. Thus, the control device can automatically check whether liquid is again in the impeller. If this is detected, the control device will resume normal operation of the circulating pump unit. The predetermined period of time may be a predetermined period of time. During this period, the drive motor is preferably out of operation.

The control device is further preferably designed such that it switches to a standby state after a predetermined number of startup attempts or after a predetermined period of time in which a startup is not successful, and preferably outputs an error message. If a dry run has been detected with the first fluid detection function or with the second fluid detection function, that is, a power consumption or a ratio of power consumption has been determined, which indicates that there is no liquid in the impeller, are preferably the Fluid recognition functions, as described above, performed repeatedly over a period of time to detect whether there is liquid in the impeller again. If the control device detects liquid in the impeller, it switches the circulating pump unit into normal operation. However, if over a predetermined period or a predetermined number of passes of the fluid detection functions, that is, a predetermined number of commissioning attempts, still no fluid is detected in the impeller, the Umwälzpumpenaggregat can turn off completely or switch to an idle state and further runs refrain from the fluid detection functions. In such a state, an error message is then preferably issued, which signals to the operator that he must check the circulating pump unit and, for example, must manually restart after venting.

In addition to the described Umwälzpumpenaggregat object of the invention is also a method for operating a circulating pump unit, which is preferably a Umwälzpumpenaggregat, as described above. According to the method of the invention, a first fluid recognition algorithm is provided, which corresponds to the above-described first fluid detection function and according to which a drive motor of Umwälzpumpenaggregates is rotated in turn at two different speeds or in both directions. The two rotational speeds or both directions of rotation are preferably applied immediately after one another in order to ensure that the state, in particular the hydraulic resistance of the connected hydraulic system, does not substantially change in this time span. During operation of the drive motor with the different speeds or in the different directions of rotation, the electrical power consumption is detected in each case. Subsequently, the detected electrical power consumption for the different speeds or directions of rotation are evaluated to detect at least one property of the fluid and the presence of a liquid in the impeller. This is done in a manner as described above with reference to the circulating pump unit in which this method is used. In this respect, reference is made to the above description. The above-described features and preferred features of the circulating pump unit are preferably also the subject of the method according to the invention.

Preferably, the recorded at different speeds or in different directions of rotation electrical power consumption are compared with each other, wherein a ratio of the power consumption to each other a condition of the fluid is detected in the circulating pump unit. Also in this regard is on the above description with respect to the circulating pump unit referenced. In the case of different directions of rotation, a dry run can be recognized, in particular, by the fact that the recorded power consumptions essentially have the ratio 1 to one another. This corresponds essentially to the same power consumption in both directions of rotation.

In the method, a second fluid recognition algorithm, which corresponds to the above-described second fluid recognition function of the circulating pump unit, is preferably used. According to the second fluid recognition algorithm, during operation, that is to say during normal operation of the circulating pump assembly, the electric power consumption of the drive motor is compared with a lower limit and a fall below this lower limit as a feature for a particular condition of a fluid in the circulating pump unit and especially for a dry run considered , For this purpose, the power consumption, for example, from the control device described above, continuously or at predetermined time intervals are detected and compared with a corresponding lower limit. As described above, the lower limit may also be a limit curve which depends on the rotational speed.

The second fluid recognition algorithm is preferably used when, according to the first fluid recognition algorithm, a certain property of the fluid in the impeller and in particular for the first time a fluid in the impeller has been detected. Also in this regard, reference is made to the above description with reference to the Umwälzpumpenaggregates.

Fig. 1

eine teilweise geschnittene perspektivische Ansicht eines erfindungsgemäßen Umwälzpumpenaggregates,

Fig. 2

in einem Ablaufdiagramm den Start einer Trockenlauf-Prüfung bei Inbetriebnahme des Umwälzpumpenaggregates,

Fig. 3

in einem Ablaufdiagramm einen ersten Fluid-Erkennungs-Algorithmus,

Fig. 4

schematisch die Leistungsaufnahme des Pumpenaggregates bei verschiedenen Drehzahlen,

Fig. 5

in einem Ablaufdiagramm einen zweiten Fluid-Erkennungs-Algorithmus und

Fig. 6

ein Ablaufdiagramm eines Selbsttest bei Anwendung des zweiten Fluid-Erkennungs-Algorithmus.

The invention will now be described by way of example with reference to the accompanying drawings. In these shows:

Fig. 1

a partially cutaway perspective view of a Umwälzpumpenaggregates invention,

Fig. 2

in a flow chart the start of a dry run test when commissioning the circulating pump unit,

Fig. 3

in a flowchart a first fluid recognition algorithm,

Fig. 4

schematically the power consumption of the pump unit at different speeds,

Fig. 5

in a flowchart, a second fluid detection algorithm and

Fig. 6

a flow chart of a self-test using the second fluid detection algorithm.

At the in Fig. 1 circulating pump unit shown is a circulating pump unit, as used for example in heating systems. The circulating pump unit has a pump housing 2 with connections 4 for connection to a hydraulic system. In the interior of the pump housing 2, an impeller 6 is arranged, which is connected via a shaft 8 with the rotor 10 of an electric drive motor. The electric drive motor is arranged in a rotor or stator housing 12, which is connected to the pump housing 2. The drive motor is designed as a wet-running motor and has a split tube 14 which is cup-shaped and is arranged in the interior of the rotor 10. The gap tube 14 surrounding the outer circumference of the stator 16 with the Stator coils arranged. The shaft 8 with the rotor 10 is mounted in two plain bearings 18 in the radial direction. Since the interior of the can 14 in conjunction with the interior of the pump housing 2, in which the impeller 6 rotates, is located in the interior of the can 14, a pumped from the impeller 6 liquid, especially water. The conveyed liquid is used to lubricate the bearings 18. In order to ensure adequate lubrication of the bearings 18 in this way, a dry run of the pump unit, in which no liquid is conveyed through the impeller 6, to be avoided.

Attached to the stator housing 12 is a terminal box or electronics housing 20, in which an electronic control device 22 is arranged. The control device 22 controls or controls the drive motor and has in particular a frequency converter, via which the coils of the stator 16 are energized. The speed of the drive motor can be changed and controlled via the frequency converter. On the outside of the electronics housing 20, a display device 24 is further arranged for displaying various operating conditions.

The control device 22 has a fluid detection system, which preferably serves to detect whether the impeller 6 is filled with liquid or runs dry. The fluid recognition system is particularly preferably integrated as a software module in the software of the control device 22. The control device 22 has corresponding electronic components, in particular a microprocessor, in order to carry out the required functions and software modules.

The fluid recognition system has two fluid recognition functions or fluid recognition algorithms A1 and A2. The first fluid recognition algorithm A1 and the second fluid recognition algorithm A2 are used in different operating states of the pump set.

When commissioning the pump set, the in Fig. 2 shown procedure. Thus, in step S1, a query is made as to whether a liquid has ever been detected in the circulating pump unit with the aid of the first fluid recognition algorithm A1. The control device 22 has a memory in which upon initial detection of liquid in the impeller 6 with the aid of the first fluid recognition algorithm A1, a value representing this state is set permanently, so that this value is maintained even if the circulating pump unit is temporarily switched off , The memory is preferably designed so that it also stores the value in the de-energized state, so that it is permanently stored in the pump unit, whether the pump unit was ever filled with liquid. If it is determined in step S1 when interrogating the value stored in the memory that liquid has never been detected in the circulating pump unit (N), the first fluid recognition algorithm A1 is subsequently started in step S2. If, on the other hand, the question as to whether the circulating pump unit was ever filled with liquid in step S1 is answered by querying the memory of the control device 22 with yes (Y), the second fluid recognition algorithm A2 is subsequently started in step S3. If the first fluid recognition algorithm, which is started in step S2, later detects liquid in the impeller 6 in the manner described below, the second fluid recognition algorithm A2 is subsequently also started, as in FIG Fig. 2 shown.

Fig. 3 shows the flow of the first fluid detection algorithm. When this is started, the stator 16 is initially energized by the control device 22 in step S4 in such a way that the rotor rotates in a first direction of rotation CW, for example in a clockwise direction. While This rotation is detected by the control device 22, the electrical power consumption of the drive motor. Subsequently, we stopped the drive motor and after a break in the form of the time t ₁ , for example 15 seconds, the stator 16 is energized in the following step S5 of the controller 2 such that the rotor 10 in an opposite second direction of rotation CCW, for example counter clockwise, turns. Preferably, this second direction of rotation CCW is the direction of rotation in which the drive motor rotates during normal operation. Also during this operation of the drive motor, the electric power consumption is detected by the control device 22.

In the subsequent step S6, an evaluation of the electrical power consumptions detected in the two directions of rotation CW and CCW is then carried out by the control device 22. If the power consumptions are substantially equal, this indicates that there is no water in the impeller 6, as this so opposes substantially no resistance to the drive motor. The occurring resistance is thus essentially caused by the bearings 18 and is substantially the same in both directions of rotation CW and CCW. In this respect, the question of water in the impeller is answered in the step S6 in the evaluation with no (N) and it is carried out in the following step S7, the stop of the drive motor. However, as a precaution, the drive motor could be stopped even before the execution of step S6 and would then only be halted in step S7. After a period of time t ₂ , for example 30 seconds, the step S ₄ then starts again to check again whether there is liquid in the impeller 6. If different power consumptions for the two directions of rotation CW and CCW are detected in step S6, then this speaks for water in the impeller 6 and the query in step S6 is answered accordingly with yes (Y). Subsequently, in step S8, the second fluid recognition algorithm A2 is started and stored simultaneously in the control device 22, that for the first time liquid was detected in the impeller 6. On the storage of the corresponding value is when restarting the Umwälzpumpenaggregates, as based on Fig. 2 explained, then resorted to in step S1.

The sequence of the second fluid recognition algorithm A2 is based on the Fig. 4-6 described. This in Fig. 4 The diagram shown shows the electrical power P plotted against the rotational speed N. In operation, for example, results in the power curve P1, that is, with higher speed increases the power absorbed. There are two areas 26 and 28 as they are in Fig. 4 in which the first region 26 fluid is conveyed by the impeller 6, while the second region 28 is a dry-running region. Both are separated by a limit curve 30, which forms a lower limit. That is, in normal operation of the circulating pump unit, when the impeller 6 promotes liquid, the absorbed power P is above the limit curve 30, while it is below the limit curve 30 in dry running. It can be seen that, especially at low speeds, actually occurring powers according to the power curve P1 can be very close to the limit curve 30, so that the distinction between dry running and normal operation is not always perfectly possible there.

The second fluid recognition algorithm A2 takes place during normal operation of the circulating pump unit, that is, in this the speed of Umwälzpumpenaggregates is not specifically set for fluid detection, but the speed is set by the controller 22 according to the hydraulic requirements of the circulating pump unit.

The second fluid recognition algorithm A2 starts, as in FIG Fig. 5 shown with normal operation NB. In this normal mode, the Control device 22 according to the second fluid recognition algorithm A2 in step S9 running, whether the electric power approaches the limit curve 30 or below. If a reaching of the limit curve 30 is detected by the control device 22 and in particular an undershooting, an inquiry follows in step S10 as to whether a time interval t _{3 has} elapsed since the last dry run check. If the time period t ₃ , which is permanently stored in the control device 22, has not yet expired (N), the control device 22 returns to the normal operation NB according to step S9. If it is determined in step S10 that the time period t _{3 has} elapsed (Y), the speed is increased in step S11 to the maximum speed N _max for checking the dry-running. This has the advantage that it is changed to an operating state in which the electrical power occurring in normal operation deviates more strongly from the electrical power occurring in dry running (region 28) and thus the dry run can be better detected. By prior query of the time period t ₃ prevents the circulating pump unit changes during operation too often for no reason to the maximum speed N _max or maximum power. It is assumed that not so sudden a loss of fluid in the rotor chamber, in which the bearings 18 are located, occurs that no adequate lubrication of the bearing 18 would be more. If, at the maximum rotational speed N _{max, it is determined} in step S 12 that the electrical power consumption is above the limit curve 30 and thus no dry run is given (N), normal operation NB is changed according to step S 9. If the electric power consumption is below the limit curve 30 even at maximum rotational speed N _max , it is concluded that there is dry running and the query in step S 12 is answered in the same way with yes (Y), so that subsequently in step S 13 the circulating pump unit is stopped and a self-test is performed Fig. 6 is started.

When stopping the Umwälzpumpenaggregates due to a detected dry run, either by the first fluid detection algorithm A1 or the second fluid detection algorithm A2, preferably at the same time an error message on the display device 24 is displayed by the controller 22, so that the user or operator can recognize this dry run as a fault and can remedy the situation.

In order to facilitate the commissioning of the circulating pump unit, the self-test described below is started after the dry run detected by the second fluid recognition algorithm A2. The procedure according to Fig. 6 begins with step S13, which is based on Fig. 5 was explained. In step S14, an error message or other suitable alarm is displayed. In step S15, a query is made as to whether, after the stop in step S13, a predetermined period of time t ₄ , which is stored in the control device 22, has expired. This prevents re-checking for dry running immediately after stopping. If the time period t ₄ has not yet elapsed (N), the system returns to step S13.

After elapse of the time period t ₄ (Y), the display 24 indicates in step S16 that a self-test starts and then the drive motor is started again in step S17. Again, the second fluid recognition algorithm A2 is used. If, according to this, it is determined in step S18, as explained above with reference to step S9, that the electrical power consumption is safely above the limit curve 30 and consequently no dry run is present (N), then the system returns to normal operation NB and the sequence according to FIG Fig. 5 begins again with step S9. If, however, it is determined in step S18 that when the circulating pump unit is started up at the speed according to normal operation NB, the electrical power consumption is at low speed in the vicinity of the limit curve 30 (Y), then in step S19 corresponding to step S11, the speed is increased again to the maximum speed N _max . Subsequently, in step S20, which corresponds to step S12 described above, it is checked whether the absorbed power is above or below the limit curve 30. If it is not below the limit curve 30 and thus no dry run is detected, the query is answered in step S20 with no (N) and it is transferred to the normal operation NB according to step S9. If, in contrast, a dry run is detected (Y), a query is made in step S21 as to whether a time limit T has been reached since the beginning of step S13. The time limit T may be, for example, a time of 72 hours and is stored permanently in the control device 22. If the time limit T has not yet been reached (N), the described self-test starts again with step S13. However, if the time limit T is reached (Y), a permanent stop of the circulating pump unit preferably with a corresponding error message on the display device 24 takes place in step S22. This permanent stopping of the circulating pump unit means that no further self-checks as to whether liquid is again present in the impeller 6 , and the circulating pump unit must be restarted manually. This can be done in step S23, for example by pressing a corresponding control element 32 on the electronics housing 20, where appropriate, several of the controls 32 must be pressed simultaneously or sequentially to take the circulating pump unit back into operation. Thereafter, the self-test starts again in step S13. Alternatively, the circulating pump unit can be disconnected from the mains. Thereafter, at startup, the procedure would revert to step S1 Fig. 2 start.

The use of the first fluid recognition algorithm A1 and the second fluid recognition algorithm A2 forms a two-stage process, which ensures that a state can be detected in which the bearings 18 are lubricated not with the liquid to be conveyed but with a previously introduced lubricant, such as glycerol, which has a higher viscosity. The higher viscosity leads to a higher friction, which could lead to a power consumption in operation, which above the in Fig. 4 shown limit curve 30, so that with the second fluid detection algorithm A2 this state could not be reliably detected. Therefore, during initial startup, the first fluid recognition algorithm A1 is used in order to be able to recognize this condition as well.

It is to be understood that in particular the first fluid recognition algorithm A1 could also be used later, that is to say after initial startup, in contrast to the example shown, for example in order to be able to recognize different liquids, for example liquids of different viscosity , Therefore, it is assumed that upon rotation of the impeller 6, in the intended direction of rotation, the hydraulic resistance is different than in the opposite direction of rotation. Also by changing the rotational speed, different fluids can be differentiated from the control device 22 in accordance with the second fluid recognition algorithm A2 due to the resulting different performance curves.

LIST OF REFERENCE NUMBERS

2

pump housing

4

connections

6

Wheel

8th

wave

10

rotor

12

stator

14

canned

16

stator

18

warehouse

20

electronics housing

22

control device

24

display

26, 28

Areas of power consumption

30

limit curve

32

controls

A1

first fluid recognition algorithm (fluid recognition function)

A2

second fluid recognition algorithm (fluid recognition function)

N

number of revolutions

N _max

maximum speed

P

power

P1

power curve

CW

first direction of rotation

CCW

second direction of rotation

NB

normal operation

S1-S23

steps

t ₁ , t ₂ , t ₃ , t ₄

periods

T

time limit

Claims (18)

1. A circulation pump assembly with a wet-running electric drive motor (10, 16), with at least one impeller (6) driven by the electrical drive motor (10, 16) as well as with an electronic control device which controls the drive motor (10, 16),
   characterised in that
   the control device (22) comprises at least one first fluid recognition function (A1), with which the control device (22) activates the drive motor (10, 16) in a manner such that it rotates successively with at least two different speeds or in different rotation directions (CW, CCW), wherein the control device (22) in each case detects the electrical power consumption (P) and recognises if a liquid or air is located in the impeller on basis of an evaluation of the detected electrical power consumptions (P) for the different speeds or rotation directions (CW, CCW).
2. A circulation pump assembly according to claim 1, characterised in that the control device (22) is designed in a manner such that it compares the detected electrical power consumptions (P) at the different speeds or in the different rotation directions (CW, CCW), with one another and recognises if a liquid is located in the impeller (6) by way of a ratio of the detected power consumptions.
3. A circulation pump assembly according to one of the preceding claims, characterised in that the control device (22) is designed in a manner such that the first fluid recognition function (A1) is carried out on starting operation of the circulation pump assembly after a standstill.
4. A circulation pump assembly according to one of the preceding claims, characterised in that the control device (22) is designed in a manner such that it issues a fault notice and/or blocks a further operation of the circulation pump assembly when the detected power consumptions are equal with both two rotation directions (CW, CCW).
5. A circulation pump assembly according to one of the preceding claims, characterised in that the control device (22) is designed in a manner such that the first fluid recognition function (A1) is repeatedly carried out as long as the evaluation of the detected electric power consumptions results in that no liquid is located in the impeller (6).
6. A circulation pump assembly according to one of the preceding claims, characterised in that the control device (22) is designed in a manner such that the first fluid recognition function (A1) is applied with a first starting operation of the circulation pump assembly, until for the first time a liquid in the impeller (6) is recognised by way of the evaluation of the detected electrical power consumptions.
7. A circulation pump assembly according to one of the preceding claims, characterised in that the control device (22) comprises a second fluid recognition function (A2), with which the control device (22), on operation of the circulation pump assembly, detects the power consumption of the drive motor (10, 16) and compares it to at least one predefined lower limit (30).
8. A circulation pump assembly according to claim 7, characterised in that the control device (22) is designed in a manner such that the second fluid recognition function (A2) is applied after a defined characteristic of the fluid in the impeller (6) and in particular a presence of a liquid in the impeller (6) has been recognised with the first fluid recognition function (A1).
9. A circulation pump assembly according to claim 7 or 8, characterised in that the lower limit is a limit curve (30) with a dependency on the speed (N) of the drive motor (10, 16).
10. A circulation pump assembly according to one of the claims 7 to 9, characterised in that the control device (22) is designed in a manner such that the control device (22) issues a fault notice and/or stops the drive motor (10, 16) on falling short of the lower limit (30) for the power consumption (P).
11. A circulation pump assembly according to one of the claims 7 to 10, characterised in that the control device (22) is designed in a manner such that for the second fluid recognition function (A2), it increases the speed (N) and/or the power (P) of the drive motor (10, 16), at least in temporal intervals.
12. A circulation pump assembly according to one of the claims 7 to 11, characterised in that the control device (22) is designed in a manner such that on falling short of the lower limit (30), it stops the drive motor (10, 16) and after a defined time duration (t₄) it carries out the second fluid recognition function (A2) afresh amid starting operation of the drive motor (10, 16).
13. A circulation pump assembly according to one of the preceding claims, characterised in that the control device (22) is designed in a manner such that after a defined number of starting operation attempts or after a defined time duration (T), in which a starting operation has not been successful, it switches into an idle condition and preferably issues a fault notice.
14. A method for the operation of a circulation pump assembly which in particular is designed according to one of the preceding claims, characterised by a first fluid recognition algorithm (A1), according to which a drive motor (10, 16) of the circulation pump assembly is successively rotated at two different speeds or in both rotation directions (CW, CCW), and the electrical power consumption (P) is thereby detected in each case, and a presence of a liquid in the impeller (6) is recognised by way of evaluating the detected electrical power consumptions (P) for the different speeds or rotation directions (CW, CCW).
15. A method according to claim 14, characterised in that the two electrical power consumptions (P) which are detected at different speeds or in different rotation directions (CW, CCW) are compared with one another, wherein a nature of the fluid in the circulation pump assembly is detected by way of a ratio of the power consumptions.
16. A method according to claim 14 or 15, characterised in that the same power consumptions in both rotation directions (CW, CCW) are seen as a feature for a dry running.
17. A method according to one of the claims 14 to 16, characterised by a second fluid recognition algorithm (A2), according to which, on operation of the circulation pump assembly, the electrical power consumption of the drive motor (10, 16) is compared with a lower limit and falling short of this lower limit (30) is seen as a feature for a certain nature of a fluid in the circulation pump assembly and in particular for a dry running.
18. A method according to claim 17, characterised in that the second fluid recognition algorithm (A2) is applied after a certain characteristic of the fluid in the impeller (6) and in particular a liquid in the impeller (6) was a detected according to the first fluid recognition algorithm (A1).

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