EP4627217A1

EP4627217A1 - Method for evaluating the proper installation of a metering pump and metering pump

Info

Publication number: EP4627217A1
Application number: EP23783762.0A
Authority: EP
Inventors: Klaus Müller; Valeri Kechler; Sergei Gerz; Felix Kaufmann
Original assignee: Grundfos Holdings AS
Current assignee: Grundfos Holdings AS
Priority date: 2022-11-29
Filing date: 2023-09-29
Publication date: 2025-10-08
Also published as: CN120476257A; WO2024114972A1

Abstract

Method for evaluating the proper installation of a metering pump (2) comprising the following steps: a) setting a drive pattern to a first pattern configuration (PC_n), b) operating the metering pump (2) with said drive pattern, c) detecting a stroke-diagram (34) during operation of the metering pump (2) with said drive pattern, the stroke diagram representing a relation between a force and the stroke position, d) deriving at least one first criterion from at least one portion (38, 40) of the detected stroke-diagram(34), e) selecting an evaluation step (E_n+1) by use of a decision matrix (36) on basis of the derived criterion, f) setting the drive pattern to a second or further pattern configuration (PC_n+1) according to the selected evaluation step (E_n _+i) and repeating steps b) to f) until at least one predefined final evaluation step (F) in the decision matrix (36) is reached. Furthermore, the invention refers to a metering pump device configured to carry out this method.

Description

[01 ] The invention refers to a method for evaluating the proper installation of a metering pump and to a respective metering pump device configured to carry out such method.

[02] For control and safe operation of metering pumps, a correct installation or detailed knowledge of the installation is of importance. Incorrect installation may result in undesired cavitation or improper operation for example. Thus, the correct installation and setup of the pump control is of importance and require detailed knowledge and experience of the designer, the installer and the user.

[03] In view of this, it is the object of the invention to simplify the installation of a metering pump and in particular to ensure a correct installation. This object is achieved by a method having the features defined in claim 1 and by a metering pump device having the features defined in claim 15. Preferred embodiments are defined in the subclaims, the following description and the accompanying drawings.

[04] According to the invention there is provided a method for evaluating the proper installation of a metering pump. This is a method which is carried out by an electronic control device to allow an automatic evaluation of the installation or commissioning of a metering pump. The method may be incorporated in a control software of the metering pump carrying out an evaluation procedure according to this method to evaluate the correct or proper installation of the pump, for example prior to starting operation of the metering pump.

[05] According to the method a drive pattern of the metering pump is set to a first pattern configuration. The drive pattern is a pattern according to which the drive operates the metering pump, in particular moves a displacement element inside the pump. In particular, the drive pattern defines the speed in different portions of the movement path of a displacement element. This means, the speed may vary during a movement cycle and/or the pump may stop at one or more predefined stroke position. In the first step of the method, the drive pattern is set to a first pattern configuration which may be a predefined pattern configuration for starting the method or the evaluation step, respectively. In the next step the metering pump is operated with the drive pattern set to the first pattern configuration. During this operation there is detected a stroke-diagram. The stroke-diagram shows a force and/or pressure produced by the metering pump or applied to the fluid over the stroke length or pump cycle, respectively. For the stroke-diagram it is possible to detect the pressure of the pumped fluid, for example inside a pump chamber. Instead of directly detecting the pressure, it is possible to detect the force acting on the pump drive or onto a displacement element inside the metering pump. Furthermore, any other suitable value representing the force and/or pressure may be detected or derived, for example by suitable sensors. For example, it may be possible to detect electric values of the electric drive representing the torque produced by the drive. In knowledge of the drive geometry, it is possible to calculate the force acting on a displacement element and the pressure applied to the fluid, i.e. there is a known relation between those values and the pressure or force. Thus, instead of regarding the force or pressure in the stroke-diagram stroke-diagramit would also be possible to regard a torque or an electric value representing the torque in such diagram. All these possibilities should be covered by the definition “stroke-diagram” used in the following.

[06] In the next step there is derived at least one criterion, in the first evaluation step a first criterion, from at least one portion of the detected stroke-diagram. For example, the position of a characteristic point of the diagram may be regarded and it is possible to detect the stroke length and/or the force for this characteristic point in the diagram. Furthermore, a portion of the diagram and the force or pressure curve in this portion may be regarded as a characteristic criterion. In the next step a decision matrix or decision free, respectively, is used to make a decision on how to proceed with the evaluation procedure. This means, the next step of the evaluation procedure is decided on basis of the derived (first) criterion, i.e. by comparing the criterion with predefined values or characteristics. Depending on the result of this evaluation or comparison it is decided which should be the next or following evaluation step. On basis of this decision in the next evaluation step the drive pattern is set to a second or further pattern configuration corresponding to the selected evaluation step and then in the following the described steps are repeated, i.e. the metering pump is operated with the drive pattern having the second or further configuration and then again a certain criterion is derived from a detected stroke-diagram and, then, in the decision matrix a next decision is made on how to proceed. This procedure may be repeated for several steps. In particular, each evaluation step can be used to further specify a certain fault in the installation or to evaluate different aspects or possible faults in the installation, like for example cavitation, too high or too low pressure on the outlet side of the pump etc.

[07] The essential part of the method is to use a decision matrix having different evaluation steps and in each step making a decision which should be the next evaluation step. These decisions may be de- cisions between two or more alternative evaluation steps. In particular, the decisions include a comparison of the criterion with a predefined characteristic or characteristic value like a threshold. For example, if the criterion is above a predefined threshold, a first possible evaluation step will follow, whereas in case the criterion is below a threshold a second alternative evaluation step will follow.

[08] The method according to the invention in particular is configured for use with a metering pump being a positive displacement pump, preferably having a reciprocating displacement element. The reciprocating displacement element preferably is driven by an eccentric drive mechanism which is driven by an electric drive motor, preferably a stepper motor. In such a drive mechanism the movement for example is recorded by an angle sensor or on basis of electric values from the drive motor. Alternatively, it is possible to provide any other suitable position sensor in the drive means to detect the position of the displacement element, in particular the linear position of the displacement element. The displacement element may for example be a plunger or membrane moved in reciprocating manner.

[09] According to a further embodiment, when repeating the step of deriving at least one criterion from the at least one portion of the detected stroke-diagram a second and/or a further criterion are derived or considered. This means, in the different evaluation steps in the decision matrix different criteria may be derived and regarded. This may be used to further specify a certain possible fault or to evaluate different possible faults in the installation.

[10] As described above, the drive pattern defines the motion of the drive during a pump cycle, for example one movement of a reciprocating displacement element back and forth. The drive pattern for ex- ample may define speed, changes in speed and/or stops of the metering pump, preferably along at least one stroke or cycle of the metering pump. Furthermore, the drive pattern may define several pump cycles or strokes. For example, the speed may vary over several cycles or strokes of the metering pump. All these different operating conditions or configurations are set in a pattern configuration as mentioned above.

[1 1 ] After setting the drive pattern to a first or further pattern configuration, in the following step, preferably, the metering pump is operated for a predefined amount of time, a predefined number of strokes or a predefined stroke length. The duration of operation or number of strokes or the stroke length may be set for the respective evaluation step depending on the criterion to be analyzed. For example, the criterion may be a shift of a certain point in the stroke-diagram or a curve in the diagram. This requires an operation for a certain time to detect this shift. Furthermore, the operation for several strokes or a long duration may result in a more accurate evaluation.

[12] The at least one final evaluation step may comprise an output, an interim result or a final result and/or a predefined action of the metering pump may be initiated in the final evaluation step. For example, the result may be that the installation is correct or may indicate a certain fault detected. Furthermore, the result of the evaluation may be a certain set up for the further operation of the pump, for example a maximum drive speed, for example in a pressure or suction stroke.

[13] The at least one criterion mentioned above, preferably is at least one force or pressure value and/or a force or pressure curve in at least one portion of the stroke-diagram. A force or pressure value in the meaning of this invention may be a value representing a force or pressure or a value derived from a force or pressure detected. Furthermore, it may be a value representing a parameter which is proportional with a force or pressure value. This may for example be a torque of a drive motor or an electric value being representative for such torque. The criterion for example may be the force or pressure occurring at a certain point or portion of a stroke. Furthermore, it may be possible to regard the entire curve in a certain portion of the pump cycle or stroke.

[14] The at least one portion of the stroke-diagram may for example represent at least a section of a suction and/or pressure stroke. This may be a characteristic point or section of the suction and/or pressure stroke. For this portion, for example the pressure or force values may be regarded as a criterion as discussed before.

[15] According to a further possible embodiment, the at least one criterion defines a stroke position in the stroke-diagram, preferably a position of a remarkable change in force, for example the position at which pressure build-up starts. Thus, the criterion may define a characteristic portion or characteristic point in the stroke-diagram, in particular a point at which the stroke direction changes, for example between suction and pressure stroke, or at which essential changes in pressure occur, for example, when the pressure build-up starts after the suction stroke, i.e. at the beginning of the pressure stroke. The pressure or force detected at those characteristic points may indicate certain malfunctions or installation problems. In addition or alternatively, the position of the characteristic point along the stroke length may indicate a malfunction or incorrect installation.

[16] Furthermore, the drive pattern in its drive pattern configuration may include a stop at a predefined position of the stroke. The derived criterion in this case may be a detected change in pressure after the stop. For example, a pressure loss after a stop in the pressure stroke may indicate a leakage in the pump chamber, the membrane and/or for example in one of the valves.

[17] Preferably the predefined position mentioned before is a position in the pressure stroke, a position in the suction stroke or position at a transition between suction and pressure stroke or between pressure and suction stroke. These are examples of characteristic points or portions in the stroke-diagram. In case of proper operation, these characteristic points or portions have a predefined shape or predefined position. Deviations from the predefined position or from a predefined pressure or force range at the respective position may indicate an improper installation of malfunction.

[18] According to a further possible embodiment the derived criterion is a change in pressure or force exceeding a predefined threshold. The threshold may be a predefined minimum or maximum. For example, a too high pressure in the pump chamber may indicate a closed valve or outlet line. A too low pressure on the other hand may for example indicate a closed suction line or a suction valve or a too long suction line etc.

[19] One possible installation problem which may be detected or evaluated by the method is whether there is a sufficient back pressure in the outlet line of the metering pump. For evaluating whether there is a sufficient back pressure for the metering pump, the drive pattern at the beginning of this evaluation step is set to a first pattern configuration comprising a first drive speed. Thus, the pump and in particular a displacement element like a plunger or a membrane is moving with a first drive speed. With this first drive speed, the at least one criterion detected and analyzed may be the maximum force or pressure, which can be achieved during the pressure stroke. If the detected maximum pressure or force is below a predefined threshold, i.e. a minimum value, in the following step the drive pattern is set to a second pattern configuration comprising a second, higher drive speed. Thus, the second pattern configuration comprises a second drive speed which is higher than the first drive speed in the first pattern configuration used before. In the following the pump is operated with the second pattern configuration, i.e. with the second higher drive speed. During this operation, again the at least one criterion is detected, i.e. the maximum force or pressure achieved during the pressure stroke is detected. If this detected maximum force or pressure is still below the predefined threshold, a predefined final evaluation step has been reached. In this final evaluation step the result may be output to a user or operator indicating that there is no sufficient back pressure for the metering pump. If by increasing the speed the pressure cannot be increased above the desired minimum pressure this is an indication for a too low back pressure on the outlet side of the metering pump. This indicates an improper installation of the pump which should be changed before operation. The evaluation whether there is sufficient back pressure may be carried out in more than two evaluation steps, i.e. the speed may be increased in several steps before the final evaluation step is reached.

[20] A further problem which may be detected by the method may be cavitation. For evaluating cavitation according to the method, preferably the drive pattern is set to a first pattern configuration comprising a first drive speed. In the following the pump is operated with this first drive speed and as the at least one criterion the stroke position at which the pressure build-up starts is detected in the stroke-diagram. The detected position is compared with a predefined stroke length defining a threshold for the position at which the pressure build-up should start. If it is detected that the actual position of the start of pressure build-up is above the predefined stroke length this is an indication for cavitation inside the dosing head or pump chamber, respectively. For the further evaluation in a following evaluation step, the speed pattern is set to a second pattern configuration comprising a second, lower drive speed, i.e. drive speed which is lower than the first drive speed used in the evaluation step before. In the following the pump is operated with this second lower drive speed and again as the least one criterion the stroke position at which the pressure build-up starts is detected in the stroke-diagram. If the stroke position is below the predefined stroke length, i.e. below the predefined threshold, a maximum drive speed to avoid harmful cavitation has been found and a final evaluation step has been reached. It may be that more than two evaluation steps are required to find the maximum drive speed allowing an operation without harmful cavitation. This may require reducing the drive speed in the different pattern configurations for the different evaluation steps in more than two steps. Furthermore, this may require a certain increase in drive speed decreasing the steps of speed change to more precisely evaluate the maximum possible drive speed without harmful cavitation. In case that a minimum drive speed has been reached and the stroke position at which the pressure build-up starts is still above the predefined stroke length, i.e. the predefined minimum stroke length, a final evaluation step has been reached, indicating that an operation without harmful cavitation is not possible. This may be output to an operator so that the operator can change the installation to avoid cavitation. For example, a suction line with greater cross section or a shorter suction line may be used to reduce the cavitation.

[21 ] Beside the method as explained before, a metering pump is subject of the present invention. Preferred embodiments of this metering pump or metering pump system are described in the following. However, preferred embodiments of the method as discussed before should be regarded as preferred embodiments of the metering pump system or metering pump device, too. Furthermore, details and method steps described in the following with reference to the metering pump device or system should be regarded as preferred embodiments of the method as described above.

[22] The metering pump device according to invention comprises at least one movable displacement element, for example a plunger or membrane. Furthermore, it comprises an electric drive moving this displacement element, preferably in a reciprocating manner. The electric drive may be an electric motor, for example a brushless DC-motor, a stepper motor, driving the displacement element by a suitable gear or transmission system, for example an eccentric drive. Alternatively, the electric drive may be a linear drive or a magnetic drive. The metering pump device, furthermore, comprises at least one electronic control device which is configured to control the metering pump device and its electric drive. Said at least one electronic control device comprises an installation evaluation module which is configured such that it carries out the method as described above. The installation evaluation module may for example be a software module inside the electronic control device. The installation evaluation module may be configured to start an installation evaluation procedure after set up of the pump device or for example on demand by an operator. The installation evaluation module preferably is configured to automatically carry out several evaluation steps on basis of a decision matrix, evaluating different possible malfunctions or installation problems and in the result set up the control to avoid malfunctions and/or to output instructions to the operator informing the operator which changes in the installation are required or which parts of the installation should be manually checked.

[23] According to a further possible embodiment the metering pump device comprises at least one sensor means which is connected to the electric control device and/or integrated into the electronic control device. Preferably, the at least one sensor means is configured to detect a force or pressure, preferably the force or pressure acting on the displacement element and/or the position of the displacement element. The sensor means for example may be a pressure sensor detecting the pressure inside a pump chamber whose volume is reduced and increased in alternating manner by movement of the displacement element. The pressure sensor may be integrated into the pump device such that it is internally connected to the electronic control device. However, in an alternative embodiment an external connection, for example a wire connection may be possible. Furthermore, other sensor means like position sensors or angle sensors may be arranged inside the metering pump device in particular inside the drive of the metering pump device. Furthermore, a configuration of the electronic control device monitoring suitable electric values of an electric drive motor may be regarded as sensor means. All these sensor means may be internally connected to the electronic control device or may have an external connection to the electronic control device, for example if the electronic control device is an external electronic control device connected to the electric drive, for example via cable or wireless connection. In further possible embodiments one or more sensor means may be external sensors which are connected to the metering pump device. Those external sensors for example may be pressure sensors arranged inside an installation connected to the metering pump. These sensors may be regarded as part of the metering pump device or as part of a metering pump system comprising at least one metering pump device and at least one sensor means. A metering pump system may comprise a central electronic control device controlling several metering pump devices. In this case the installation evaluation module may be a central control module carrying out the evaluation for different metering pump devices in the system.

[24] Preferably the installation evaluation module is a software module executed by an electronic control device being part of a pump unit comprising the electric drive and the displacement element. Alter- natively, the installation evaluation module may be executed by a control device arranged remotely from the pump unit and connected to the pump unit via a communication link. Thus, it would be possible to implement the installation evaluation module in an electronic control device arranged distanced to the metering pump devices, for example as a cloud computing system connected to one or more metering pump devices via a communication line or network like the internet.

[25] In the following the invention is described by way of example with reference to the enclosed figures. In these:

Figure 1 schematically shows a metering pump device.

Figure 2 is a flow diagram schematically showing a method according to the invention.

Figure 3 is a flow diagram schematically showing a decision matrix as used in the invention.

Figure 4 schematically shows the detection of missing back pressure by use of the stroke-diagram.

Figure s schematically shows the detection of harmful cavitation by use of the stroke-diagram.

Figure 6 schematically shows the detection of a leakage in the suction valve by use of the stroke-diagram.

Figure 7 schematically shows a pressure detection in the strokediagram to further specify a problem of the installation. [26] The method according to the invention is configured for use with a metering pump device or metering pump installation as basically explained with reference to figure 1. Figure 1 shows a metering pump device 2 comprising a drive 4 with a pump head or dosing head 6, respectively. Inside the dosing head 6 there is a pump chamber 8 which volume is variable by movement of a diaphragm 10. The diaphragm 10 is moved by the drive 4. For example, the diaphragm 10 is moved via a rod moved in reciprocating manner by a linear drive, a magnetic drive or a rotatable electric drive motor connected to the rod via an eccentric drive mechanism. The electric drive motor for example may be a stepper motor. The dosing head 6 comprises an inlet or suction valve 12 and a pressure or outlet valve 14. The inlet valve 12 is connected to a suction line 16, for example extending into a liquid container 18. The outlet valve 14 is connected to a pressure line 20 extending towards or being connected with a facility to which a liquid is supplied by the metering pump device 2. By movement of the diaphragm 10 liquid is sucked out of the liquid container 18 and pumped into the pressure line 20. By regulating speed and/or stroke length of the diaphragm 10 the amount of liquid per time can be varied.

[27] The metering pump device 2 furthermore comprises an electronic control device 22 which is configured to control the drive. In particular, the electronic control device 22 can adjust speed and/or stroke length of the movement of the diaphragm 10. The electronic control device 22 may comprise a suitable microprocessor, storage means, and further electronic components required. In particular, the control device is configured to execute at least one control program. The metering pump device 2 comprises sensor means connected to the control device 22 and providing sensor information used for control and monitoring the operation of the metering pump device 2. In this example, there is provide a pressure sensor 23 at the pump chamber 8 detecting the liquid pressure inside the pump chamber 8. The drive 4 is configured to detect and log the stroke position of the diaphragm 10. The control device 22 is configured to detect a pressure-stroke-diagram or force-strike-diagram, respectively, on basis of the detected stroke position and the pressure values detected by the pressure sensor 23.

[28] Furthermore, the electronic control device 22 may comprise a communication link 24 configured for communication with external components and control devices as for example a mobile device 26 like a mobile computer, smartphone or tablet computer, or with the internet including cloud computing devices 28. Via a communication link 24 the metering pump device 2 may be at least partly controlled by an external control device or may receive a desired set up configuration for the control device 22. Additionally, a communication link 24 may be used for output information from the electronic control device 22 to an external control system and/or to an operator. In addition, or as an alternative, the control device 22 may comprise a display 30 to output information to an operator. Furthermore, the control device 22 may comprise input means 32 for set up the control device 22.

[29] The control device 22 or an external control system which may be implemented as a cloud computing device 28 include an installation evaluation module which is configured to execute a method for evaluating the proper installation of the metering pump. The proper installation may include for example the evaluation of one or more of the following problems or malfunctions:

Too low back pressure in the pressure line 20, malfunction of pressure retaining valve, no pressure line 20 connected Too high back pressure, pressure line 20 is closed

Too low pressure, small indicator diagram (stroke-diagram) Air inside dosing head 6 or pump chamber 8 Harmless cavitation, poor dimensioning of suction line for example

Harmful cavitation, suction line 16 is closed for example

Increase of cavitation (for example wrong dimensioning of suction line 16)

Pulsation, for example because of missing pulsation damper Pressure loss in suction or discharge stroke, for example because of a leakage in a valve or the pump chamber 8.

[30] The installation evaluation procedure according to the inventive method may be started after installation of the pump, either manually by an operator or automatically. Additionally, the procedure may be carried out from time to time to check the installation for certain malfunctions and/or to monitor the operation of the metering pump device.

[31 ] As shown in principle in figure 2 after start S of the procedure the pump is operated in an evaluation step E_n, i.e. at the beginning in a first evaluation step Ei with a first predefined pattern configuration PCp Thus, the drive pattern of the metering pump device 2 on basis of which the drive 4 is operated under control of the electronic control device 22 is set to a first pattern configuration PCi, in particular having a first predefined drive speed. During this operation a stroke-diagram 34 is recorded. In the stroke-diagram 34 the pressure inside the pump chamber 8 detected by pressure sensor 23 or a relating value as for example a force or torque acting in the drive 4 is recorded in dependency of the stroke length or stroke position of the linear movement of the diaphragm 10. The stroke-diagram 34 shows a force or pressure p on the ordinate and the stroke length or stroke position s on the abscissa. This detected stroke-diagram 34 is evaluated by deriving and considering at least one first criterion from the detected stroke-diagram 34. This is done in an analyzing step A_n by use of a decision matrix 36 or de- cision tree, respectively. The decision matrix 36 defines the different evaluation steps E_n with the corresponding analyzing steps A_n and predefined options for the following evaluation steps E_n+i for different results R_n of the analyzing step A_n. Depending on the respective options in the decision matrix 36 there is a result R_n from the analyzing step A_n. This result R_n may be an interim result or an end result. With the end result the evaluation procedure comes to a final step F which may be for example the stop of the operation, in case that the detected malfunctions do not allow a normal operation, or may be the normal operation if a suitable set up could be found in the installation evaluation procedure. Depending on the decision matrix 36 the interim result R_n may require a further evaluation step E_n+i. For this, the drive pattern for the next evaluation step E_n+i may be changed to a second or further pattern configuration PC_n+i before starting the next evaluation step E_n+i. Thus, following the branches in the decision matrix 36 several evaluation steps E_n with respective analyzing steps A_n are carried out to detect and specify different installation problems.

[32] An example for a decision matrix 36 is given in figure 3. The example in figure 3 is a decision matrix 36 used to detect and analyze cavitation. After start S in a first evaluation step Ei the drive 4 is operated with a medium speed, for example 50% of the maximum speed. During this operation for predefined duration or a predefined number of strokes, a stroke-diagram 34 is detected and analyzed in an analyzing step Ai. If there is detected an overpressure, the pump is directly stopped as a final result F If in the analysis Ai a too high pressure or cavitation is detected, then in an interim result Ri_a in the following the drive pattern is set to a second pattern configuration PC₂ having a further reduced speed, for example a speed of 25%. In the following evaluation step E₂ the pump device is operated with this further reduced speed, i.e. a drive pattern having the second pattern configuration PC₂. If an overpressure is detected in step E₂ the operation is stopped as a final result F₂. If in an analyzing step of evaluation step E₂ there is detected cavitation or high pressure as a result R_2a, a third evaluation step E₃ will follow with a third pattern configuration PC₃ for a further detailed analysis. In this analysis the drive 4 is moved to a predefined stroke position in the suction stroke. At this position the drive 4 is stopped and the pressure p is monitored. If the pressure drops, this may indicate a wrong dimension of the suction line 16 for example which may be output as a result R_3a. If the pressure is stable, this may be an indication that the suction line 16 is closed which may be output as a result R_3b which, then, may be a final result F or the end of this evaluation procedure. If in the evaluation step E₂ no cavitation is detected, in this example no further evaluation step follows this result R_2b and the control device 22 sets the metering pump device 2 into the mode O of normal operation.

[33] If in the first evaluation step Ei no cavitation is detected, this is a second possible result R_lb of the first evaluation step. Then in the following in step the drive pattern is set to a pattern configuration PC corresponding to the normal operation. During this normal operation the pressure stroke-diagram 34 may be derived and monitored. If cavitation should be detected in a monitoring step M the control device 22 may reduce the drive speed and go and start an evaluation procedure, for example the evaluation step Ei. If no cavitation is detected the mode of normal operation O is continued.

[34] Figure 3 just shows an example for a decision matrix 36. In practice, the decision matrix 36 may have much more evaluation steps and/or branches, i.e. is being more complex to analyze different installation problems and/or malfunctions. Further examples for possible evaluation steps which may be part of such decision matrix 36 are explained with reference to figures 4 to 7. [35] Figure 4 shows an example to detect whether there is a sufficient back pressure in the pressure line 20. In a first evaluation step the drive 4 is operated with a first speed, i.e. a first pattern configuration, for example having a medium drive speed. In this example, the portion 38 of the curve in the stroke-diagram representing the pressure stroke is below a predefined minimum pressure P_min. Instead of the pressure the force or a torque acting on the drive 4 may be regarded. Then, the force would be below a minimum force. For a second evaluation step, the drive pattern is set to a second pattern configuration PC₂ and the pump device is again operated for a few strokes. In this second evaluation step, the pump is operating with a higher speed, preferably the maximum speed. If in this second evaluation step with a higher speed the pressure or force in the portion 38 of the stroke-diagram is still below the predefined minimum pressure P_min this is an indication for a missing back pressure, for example because of a defect pressure retaining valve in the pressure line 20. If with a higher speed the portion 38 is above the predefined minimum pressure P_min, this is an indication for a sufficient back pressure so that a correct pressure build up can be achieved with a higher pressure. Then, as a result the metering pump device 2 may continue normal operation or further evaluation steps for detecting different malfunctions may follow before starting the normal operation.

[36] The example in figure 5 shows a possibility to detect harmful cavitation. For the evaluation of cavitation in a first evaluation step the drive pattern is set to a first pattern configuration having a medium speed and the drive 4 is operated for a few strokes. The detected stroke-diagram or pressure-stroke-diagram 34, respectively, in case of cavitation shows that at the end 42 of the suction stroke, i.e. at the left end of the diagram, there is no direct start of a pressure build up. In this case the pressure build up starts after a stroke length of the pressure stroke. Furthermore, during the suction stroke 40, there occurs a nega- five pressure in case of cavitation. For a following second evaluation step the drive pattern is changed to a second pattern configuration PC₂ having a reduced speed at least during the suction stroke 40. Then, it is analyzed in the stroke-diagram 34 whether there is still cavitation. The lower left diagram in figure 5 shows that the stroke length l₂ is reduced compared to the stroke length in the first evaluation step. Thus, the cavitation is reduced. However, there is still cavitation occurring, the pressure build up does not directly start, but starts after the stroke length l₂ in the pressure stroke. In a following evaluation step, it may be possible to further reduce the speed during the suction stroke to evaluate whether a suction speed without occurring cavitation could be found and whether such suction speed would be acceptable for operation. An alternative result in the second or further evaluation step may be that no cavitation occurs anymore. This is shown in the lower right diagram in figure 5. There, the pressure build up directly begins at the end point 42 of the suction stroke.

[37] Figure 6 shows an example for evaluation of a possible leakage in the suction valve 12. In a first evaluation step the pump is started with a drive pattern according to a first pattern configuration having a medium speed. As can be seen in the upper force-pressure-diagram 34 in figure 6 the portion 38 of the curve representing the pressure stroke decreases towards the end 44 of the pressure stroke. This may be an indication for a leakage. In following evaluation steps this possible leakage may be further analyzed. For example, in a following evaluation step the pressure stroke may be stopped at point 46 as shown in the left lower diagram in figure 6. If the pressure detected by pressure sensor 23 drops after this stop, this is an indication for a leakage in the pump chamber or of the suction valve 12. By an increase of the speed the pressure loss may be reduced or moved towards the end point 44 of the pressure stroke 38 as shown in the lower right diagram in figure 6. Thus, according to the method it is not only possible to detect malfunc- tions, but in addition it is possible to find a set up at least partly compensating installation problems, for example by increasing the speed in the pressure stroke 38 or reducing the speed in the suction stroke 40 (to avoid cavitation).

[38] Figure 7 shows a further example of a force-stroke-pattern 34 including examples for further evaluation of certain installation problems. For a detailed analysis it is possible to stop the stroke at certain points 46, 48, 52 or 54 for example to make a further analysis. For example, as explained before with reference to figure 6 the drive 4 may be stopped at a point 46 approximately in the middle of the pressure stroke 38. This allows to detect a leakage as explained with reference to figure 6. Furthermore, it would be possible to detect a pulsation as schematically shown in figure 7. A further possibility would be to stop the suction stroke for example at a point 54 approximately in the middle of the suction stroke 40. At this point, a leakage in the pressure valve 14 could be detected. In case that the pressure increases this is an indication for a leakage in the pressure valve 14. A stop at the beginning of the pressure stroke at point 48 would allow to detect a too high suction height of the suction line 16, for example if at the beginning of the pressure stroke there is still a negative pressure. Furthermore, starting from a stop in the middle 54 of the suction stroke 40 it would be possible to detect the time until pressure equalization, which may be an indication for friction and/or inertia allowing to further specify the reason for cavitation.

List of reference numerals metering pump device drive dosing head pump chamber diaphragm inlet valve outlet valve suction line liquid container pressure line electronic control device pressure sensor communication links mobile device internet/cloud computing device display input means stroke-diagram, pressure-stroke-diagram decision matrix portion of the curve representing pressure stroke portion of the curve representing suction stroke end point of suction stroke end point of pressure stroke point during pressure stroke , 52, 54 points in force stroke-diagram E_n evaluation step

A_n analyzing step

R_n result PC_n pattern configuration

Claims

Claims Method for evaluating the proper installation of a metering pump (2) characterized by the following steps: a) setting a drive pattern to a first pattern configuration (PC_n), b) operating the metering pump (2) with said drive pattern, c) detecting a stroke-diagram (34) during operation of the metering pump (2) with said drive pattern, the stroke diagram representing a relation between a force and the stroke position, d) deriving at least one first criterion from at least one portion (38, 40) of the detected stroke-diagram(34) , e) selecting a following evaluation step (E_n) by use of a decision matrix (36) on basis of the derived criterion, f) setting the drive pattern to a second or further pattern configuration (PC_n+i) according to the selected evaluation step, (E_n+i) and repeating steps b) to f) until at least one predefined final evaluation step (F) in the decision matrix (36) is reached. Method according to claim 1 , characterized in that the metering pump is a positive displacement pump, preferably having a reciprocating displacement element (10). Method according to claim 1 or 2, characterized in that when repeating step d) a second and/or a further criterion are derived. Method according to one of the claims 1 to 3, characterized in that the drive pattern defines the speed, changes in speed and/or stops of the metering pump, preferably along at least one stroke of the metering pump. Method according to one of the preceding claims, characterized that in step b) the metering pump (2) is operated for a predefined amount of time, a predefined number of strokes or a predefined stroke length. Method according to one of the preceding claims, characterized in that in the at least one final evaluation step (F) an interim result (R_n) or a final result is output and/or a predefined action of the metering pump (2) is initiated. Method according to one of the preceding claims, characterized in that the at least one criterion is at least one force or pressure value and/or a force or pressure curve in at least one portion of the stroke-diagram (34). Method according to one of the preceding claims, characterized in that said at least one portion (38, 40) of the strokediagram (34) represents at least a section of a suction and/or pressure stroke. Method according to one of the preceding claims, characterized in that the at least one criterion defines a stroke position (46, 48, 50, 52, 54) in the stroke-diagram, preferably a position of a remarkable change in force, for example the position at which pressure build up starts. . Method according to one of the preceding claims, characterized in that the drive pattern includes a stop at a predefined position (46, 50, 54) of the stroke and that the derived criterion is a detected change in pressure after the stop. 1. Method according to claim 10, characterized in that the predefined position is a position in the pressure stroke (38), a position in the suction stroke (40) or a position at the transition between suction (40) and pressure stroke (38) or between pressure (38) and suction stroke. . Method according to claim 10 or 1 1 , characterized in that the derived criterion is a change in pressure exceeding a predefined threshold. . Method according to one of the preceding claims, characterized in that for evaluating whether there is a sufficient back pressure for the metering pump (2): the drive pattern is set to a first pattern configuration (PCi) comprising a first drive speed, in step d) the at least one criterion comprises the maximum force or pressure achieved, in step e), if it is detected that the achieved maximum force or pressure is below a predefined threshold (P_min)» in step f) the drive pattern is set to a second pattern configuration (PC₂) comprising a second higher drive speed, and after repeating steps b) to d), if the achieved maximum force or pressure is still below the predefined threshold (P_min), a predefined final evaluation step (F) has been reached. Method according to one of the preceding claims, characterized in that for evaluating cavitation: the drive pattern is set to a first pattern configuration (PC comprising a first drive speed, in step d), the at least one criterion comprises the stroke position ( ) at which pressure build up starts, in step e), if it is detected that this position is above a predefined stroke length, in step f) the speed pattern is set to a second pattern configuration (PC₂) comprising a second lower drive speed, and after repeating steps b) to d), if the stroke position is below the predefined stroke length, a maximum drive speed to avoid harmful cavitation is found as a final evaluation step (F), or if a minimum drive speed has been reached and the detected stroke position is still above the predefined stroke length, a final evaluation step (F) has been reached. Metering pump device (2) comprising at least one movable displacement element (10), an electric drive (4) moving the displacement element (10) and at least one electronic control device (22) configured to control the metering pump device (2) and its electric drive (4), characterized in that said at least one electronic control device (22) comprises an installation evaluation module which is configured such that it carries out the method according to one of the claims 1 to 14. Metering pump device (2) according to claim 15, characterized by at least one sensor means (23) connected to the electronic control device (22) and/or integrated into the electronic control device (22), the at least one sensor means (23) preferably is configured to detect a force or pressure, preferably the force or pressure acting on the displacement ele- merit (10), and/or the position of the displacement element (10). Metering pump device (2) according to claim 15 or 16, characterized in that the installation evaluation module is a soft- ware module executed by an electronic control device (22) being part of a pump unit (2) comprising the electric drive (4) and the displacement element (10) or executed by a control device (28) arranged remotely from the pump unit (2) and connected to the pump unit (2) via a communication link