US20160177937A1 - Method for Determining a Physical Variable in a Positive Displacement Pump - Google Patents

Method for Determining a Physical Variable in a Positive Displacement Pump Download PDF

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Publication number
US20160177937A1
US20160177937A1 US14/907,851 US201414907851A US2016177937A1 US 20160177937 A1 US20160177937 A1 US 20160177937A1 US 201414907851 A US201414907851 A US 201414907851A US 2016177937 A1 US2016177937 A1 US 2016177937A1
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displacer element
pressure
metering chamber
way
set forth
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Steven Liu
Fabian Kennel
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Prominent GmbH
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Prominent GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • F04B49/065—Control using electricity and making use of computers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B13/00—Pumps specially modified to deliver fixed or variable measured quantities
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B17/00—Pumps characterised by combination with, or adaptation to, specific driving engines or motors
    • F04B17/03—Pumps characterised by combination with, or adaptation to, specific driving engines or motors driven by electric motors
    • F04B17/04—Pumps characterised by combination with, or adaptation to, specific driving engines or motors driven by electric motors using solenoids
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B17/00—Pumps characterised by combination with, or adaptation to, specific driving engines or motors
    • F04B17/03—Pumps characterised by combination with, or adaptation to, specific driving engines or motors driven by electric motors
    • F04B17/04—Pumps characterised by combination with, or adaptation to, specific driving engines or motors driven by electric motors using solenoids
    • F04B17/042—Pumps characterised by combination with, or adaptation to, specific driving engines or motors driven by electric motors using solenoids the solenoid motor being separated from the fluid flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B43/00—Machines, pumps, or pumping installations having flexible working members
    • F04B43/02—Machines, pumps, or pumping installations having flexible working members having plate-like flexible members, e.g. diaphragms
    • F04B43/04—Pumps having electric drive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/02—Stopping, starting, unloading or idling control
    • F04B49/022—Stopping, starting, unloading or idling control by means of pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/20—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by changing the driving speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B51/00—Testing machines, pumps, or pumping installations
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
    • F04B53/10—Valves; Arrangement of valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B19/00—Testing; Calibrating; Fault detection or monitoring; Simulation or modelling of fluid-pressure systems or apparatus not otherwise provided for
    • F15B19/007—Simulation or modelling
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • G05B13/04—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2203/00—Motor parameters
    • F04B2203/02—Motor parameters of rotating electric motors
    • F04B2203/0201—Current
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2203/00—Motor parameters
    • F04B2203/04—Motor parameters of linear electric motors
    • F04B2203/0401—Current
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2203/00—Motor parameters
    • F04B2203/04—Motor parameters of linear electric motors
    • F04B2203/0402—Voltage
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2210/00—Working fluid
    • F05B2210/10—Kind or type
    • F05B2210/11—Kind or type liquid, i.e. incompressible
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2260/00—Function
    • F05B2260/60—Fluid transfer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S417/00—Pumps

Definitions

  • the present invention concerns a method for determining a physical variable in a positive displacement pump.
  • Positive displacement pumps generally have a moveable displacer element delimiting the metering chamber which in turn is connected by way of valves to a suction line and a pressure line.
  • delivery fluid can alternately be sucked into the metering chamber by way of the suction line by an oscillating movement of the displacer element and can be urged out of the metering chamber by way of the pressure line.
  • a drive for the oscillating movement of the displacer element is provided for that purpose.
  • the displacer element is a diaphragm which can be reciprocated between two extreme positions, wherein the volume of the metering chamber is at a minimum in the first extreme position while the volume of the metering chamber is at a maximum in the second extreme position. If therefore the diaphragm is moved from its first position into the second then the pressure in the metering chamber will fall so that delivery fluid is sucked into the metering chamber by way of the suction line.
  • the connection to the suction line is closed, the pressure of the delivery fluid will rise by virtue of the decreasing volume in the metering chamber so that the valve to the pressure line is opened and the delivery fluid is delivered into the pressure line.
  • Delivery fluid is alternately sucked into the metering chamber from the suction line and delivered from the metering chamber into the pressure line alternately by the oscillating movement of the diaphragm.
  • the delivery fluid flow in the pressure line is also referred to as the metering profile. That metering profile is substantially determined by the movement profile of the displacer element.
  • the diaphragm In the case of electromagnetically driven diaphragm pumps the diaphragm is connected to a pressure portion which in most cases is supported in resiliently prestressed fashion at least partially within a solenoid. As long as the solenoid does not have a current flowing therethrough so that no magnetic flux is built up in its interior the resilient prestressing provides that the pressure portion and therewith the diaphragm remains in a predetermined position, for example the second position, that is to say the position in which the metering chamber is at the largest volume.
  • activation of the solenoid substantially abruptly involves a stroke movement of the pressure portion and therewith the metering diaphragm from the second position into the first position.
  • such electromagnetically driven diaphragm pumps are used when the fluid volume to be metered is markedly greater than the volume of the metering chamber so that the metering speed is essentially determined by the frequency or the cycling of the flow of current through the solenoid. If for example the metering speed is to be doubled then the solenoid is briefly powered with a current twice as frequently in the same time, which in turn has the result that the movement cycle of the diaphragm takes place twice as frequently.
  • EP 1 757 809 therefore already proposes providing a position sensor with which the position of the pressure portion or the diaphragm connected thereto can be determined. Closed-loop control of the movement can then be effected by a comparison between the actual position of the pressure portion and a predetermined target position of the pressure portion.
  • the closed-loop control of the movement of the pressure portion provides that magnetic metering pumps can also be used for delivering markedly smaller amounts of fluid as the stroke movement no longer takes place abruptly but in a regulated fashion.
  • valve opening and valve closing times of the metering pump play a substantial part as they determine the beginning and the end of the actual metering operation.
  • gas bubbles in the hydraulic system and/or cavitation phenomena in the pump head of the metering unit can reduce the actual metering amount, which can markedly reduce the metering accuracy in particular when very small metering amounts are involved.
  • Such a pressure sensor however increases the cost of the metering pump, it is susceptible to faults and it has to be maintained.
  • the metering chamber has to be regularly very thoroughly cleaned.
  • the object of the present invention is to provide a method of determining a physical variable, for example the fluid pressure, with which that variable can be determined without using an additional sensor.
  • a differential equation is established based on a physical model, at least the position of the displacer element is measured and the physical variable, for example the fluid pressure, is determined by means of the differential equation.
  • the differential equation can be a movement equation.
  • movement equation is used to denote a mathematical equation which describes the spatial and temporal movement of the displacer element under the action of external influences.
  • the present invention is firstly described hereinafter referring to the example of determining the fluid pressure.
  • the invention is not limited to determining the fluid pressure. Further examples are described further hereinafter.
  • Measurement of the position of the displacer element can be effected for example in contact-free manner and is in any case generally effected in the described metering pumps so that the information about the currently prevailing position of the displacer element is available.
  • the movement equation of the displacer element takes account of all forces acting on the displacer element. Besides the force applied to the displacer element by the drive this is also the counteracting force applied by the fluid pressure in the metering chamber to the diaphragm and thus to the displacer element.
  • the positive displacement pump is an electromagnetically driven metering pump, preferably an electromagnetically driven diaphragm pump.
  • the current through the electromagnetic drive is also measured and the differential equation is used both for the position of the displacer element and also for the current through the electromagnetic drive as measurement variables. In general no further measurement variables to be detected are necessary.
  • the force on the displacer element by the drive can be determined by measurement of the position of the displacer element and measurement of the current through the electromagnetic drive and then the pressure in the metering head can be determined from the movement of the displacer element.
  • a warning signal can be output and the warning signal can be sent to an automatic shut-down arrangement which shuts down the metering pump in response to reception of the warning signal. If therefore for any reason a valve should not open or the pressure on the pressure line should rise greatly, that can be ascertained by the method according to the invention without using a pressure sensor and the pump can be shut down for the sake of safety.
  • the displacer element with the associated drive additionally performs the function of the pressure sensor.
  • a target fluid pressure curve a target position curve of the displacer element and/or the target current pattern through the electromagnetic drive is provided.
  • the actual fluid pressure can be compared to the target fluid pressure
  • the actual position of the displacer element can be compared to the target position of the displacer element and/or the actual current through the electromagnetic drive can be compared to a target current through the electromagnetic drive and a warning signal can be output if the differences between the actual and target values satisfy a predetermined criterion.
  • That method step is based on the notion that given events like for example gas bubbles in the hydraulic system or cavitation in the pump head cause a recognizable change in the fluid pressure to be expected and therefore conclusions about said events can be drawn from the step of determining the fluid pressure.
  • the warning signal can activate for example an optical display or an acoustic display. Alternatively or in combination therewith however the warning signal can also be made available directly to a control unit which implements suitable measures in response to reception of the warning signal.
  • the difference between actual and target values is determined for one or more of the measured or given variables and a warning signal is output if one of the differences exceeds a predetermined value.
  • a weighted sum of the relative deviations from the target value can be determined and the criterion so selected that a warning signal is output if the weighted sum exceeds a predetermined value.
  • Different weighting coefficients can be associated with the different fault events.
  • precisely one criterion is met so that the fault event can be diagnosed.
  • the step of determining the pressure in the metering head is possible by the described method without having recourse to a pressure sensor and conclusions about given conditions in the metering head can be drawn from the pressure determined in that way, and they can then in turn trigger the initiation of given measures.
  • Pressure variations can be very precisely determined with the method according to the invention.
  • the time gradient of a measured or given variable is ascertained and, if it exceeds a predetermined limit value, valve opening or valve closure is diagnosed.
  • the mass m of the displacer element, the spring constant k of the spring prestressing the displacer element, the damping d and/or the electrical resistance R Cu of the electromagnetic drive are determined as the physical variable.
  • all of said variables are determined. That can be effected for example by a minimization calculation.
  • All the specified variables with the exception of the pressure in the metering chamber represent constants which can be determined by experiment and which generally do not change in pump operation. Nonetheless fatigue phenomena in respect of the different elements can occur, which change the value of the constants.
  • the measured pressure-travel relationship can be compared to an expected pressure-travel relationship. The difference integrated over a cycle from both relationships can be minimized by a variation in the constant parameters. If in that case it is established for example that the spring constant has changed a defective spring can be diagnosed.
  • Such a minimization operation could also be carried out in the pressure-less condition, that is to say when there is no fluid in the metering chamber.
  • the method according to the invention can be further developed in the preferred embodiment in order to improve the closed-loop control of the pressure portion movement, more specifically without previous tabling of control parameters being necessary.
  • the metering profile which can be achieved with the positive displacement pump can be improved thereby.
  • a model-based closed-loop control in particular a non-linear model-based control, is used for the drive of the displacer element.
  • a suitable adjusting parameter can then also be calculated from that model.
  • a characteristic of such a model-based control is therefore ongoing calculation of the necessary adjusting parameter on the basis of measurement variables using the system parameters given by the model.
  • the fundamental physical system is approximately mathematically described by the modeling. That mathematical description is then used to calculate the adjusting parameter on the basis of the measurement variables obtained. Unlike the known metering profile optimization methods therefore the drive is no longer viewed as a “black box”. Instead the known physical relationships are used for determining the adjusting parameter.
  • the differential equation according to the invention of the displacer element can be used for that purpose.
  • forces which are specific to the positive displacement pump and which act on the pressure portion are modeled in the differential equation.
  • the force exerted on the pressure portion by a spring, or the spring constant k thereof, and/or the magnetic force exerted on the pressure portion by the magnetic drive can be modeled.
  • the force exerted on the pressure portion by the delivery fluid can then be treated as an interference variable.
  • a prediction for the immediately following system behaviour can then be made by such a state space model, if the measurement variables are detected.
  • the influence of the available adjusting parameters on the closed-loop control variable can be simulated in the same model.
  • the instantaneously best control strategy can then be adaptively selected by means of known optimization methods.
  • a non-linear state space model is selected, wherein the non-linear closed-loop control is effected either by way of control-Lyapunov functions, by way of flatness-based closed-loop control methods with flatness-based precontrol, by way of integrator backstepping methods, by way of sliding mode methods or by way of predictive closed-loop control.
  • control-Lyapunov functions by way of flatness-based closed-loop control methods with flatness-based precontrol, by way of integrator backstepping methods, by way of sliding mode methods or by way of predictive closed-loop control.
  • non-linear closed-loop control by way of control-Lyapunov functions is preferred.
  • Control-Lyapunov functions are for example a generalized description of Lyapunov functions. Suitably selected control-Lyapunov functions lead to a stable behaviour in the context of the model.
  • the model which forms the basis for the model-based closed-loop control is used for formulating an optimization problem in which as a secondary condition in respect of optimization, the electrical voltage at the electric motor and thus the energy supplied to the metering pump become as small as possible, but at the same time an approximation of the actual profile to the target profile which is as fast as possible and which has little overshoot is achieved.
  • the measured signals are subjected to low-pass filtering prior to processing in the fundamental model in order to reduce the influence of noise.
  • the model-based closed-loop control according to the invention has already led to a marked improvement in the control characteristic, nonetheless there can be deviations between the target profile and the actual profile. That is not to be avoided in particular in the energy-minimizing selection of the control intervention.
  • the deviation during a cycle is detected and the detected deviation is at least in part subtracted from the desired target position profile in the next cycle.
  • a “false” target value profile is intentionally predetermined for a following pressure-suction cycle, wherein the “false” target value profile is calculated from the experience acquired in the preceding cycle. If more specifically the following suction-pressure cycle entails exactly the same deviation between actual and target profile as in the preceding cycle, the use of the “false” target value profile has the result that the actually desired target value profile is achieved as a consequence.
  • the difference between the actual and the target profiles can be measured over a plurality of cycles, for example 2, and for a mean difference to be calculated therefrom, which is then at least in part subtracted from the target profile of the following cycles.
  • any function dependent on the detected difference can be used for correction of the next target position profile.
  • a physical model with hydraulic parameters is also set up for the hydraulic system and at least one hydraulic parameter is calculated by means of an optimization calculation.
  • hydraulic parameters is used to mean any parameter of the hydraulic system—apart from the position of the displacer element—that influences the flow of the delivery fluid through the metering chamber.
  • Hydraulic parameters are therefore for example the density of the delivery fluid in the metering chamber and the viscosity of the fluid in that chamber. Further hydraulic parameters are for example hose or pipe lengths and diameters of hoses and pipes which are at least temporarily connected to the metering chamber.
  • That measure makes it possible to determine hydraulic parameters without having to provide an additional sensor.
  • the system is simplest to model for the situation where the valve to the suction line is opened and the valve to the pressure line is closed. More specifically a flexible hose is frequently fitted to the valve to the suction line, and that hose ends in a supply container which is under ambient pressure.
  • That state occurs during the so-called suction stroke movement, that is to say while the displacer element is moving from the second position into the first position.
  • That hydraulic system could be described for example by means of the non-linear Navier-Stokes equation, having regard to laminar and turbulent flows.
  • density and viscosity of the delivery fluid the diameter of the hose connecting the suction valve to the supply container, the length of the hose and the difference in height that the fluid in the hose has to overcome are then also to be considered as hydraulic parameters.
  • the determining method according to the invention could be effected solely by repeated analysis of the suction stroke performance.
  • the physical model set up can be used with the hydraulic parameters determined in that way in order in turn to determine the pressure in the metering chamber. That knowledge can be used in turn to improve the movement regulation of the pressure portion insofar as the force exerted on the pressure portion by the fluid is modeled by the hydraulic parameters determined in that way.
  • FIG. 1 shows a diagrammatic view of a pressure-travel graph and a travel-time graph for the normal condition
  • FIG. 2 shows a diagrammatic view of a pressure-travel graph and a travel-time graph for a condition with gas bubbles in the metering chamber
  • FIG. 3 shows a diagrammatic view of an ideal movement profile
  • FIG. 4 shows a diagrammatic view of the self-learning function
  • FIG. 5 shows a diagrammatic view of the suction line connected to the positive displacement pump
  • FIGS. 6 a -6 e show examples of hydraulic parameters and their time-dependent development.
  • a magnetic metering pump has a moveable pressure portion with a thrust rod fixedly connected thereto.
  • the pressure portion is supported axially moveably along the longitudinal axis in a magnet casing fixedly anchored in the pump housing so that the pressure portion with thrust rod is pulled into a bore in the magnet casing upon electrical actuation of the magnetic coil in the magnet casing, against the force of a compression spring, and the pressure portion reverts to the initial position due to the compression spring after deactivation of the solenoid.
  • the pressure portion and a diaphragm actuated thereby upon continued activation and deactivation of the magnetic coil, performs an oscillating movement which in the metering head arranged in the longitudinal axis, in conjunction with an outlet and inlet valve, leads to a pump stroke (pressure stroke) and an intake stroke (suction stroke).
  • Activation of the magnetic coil is effected by applying a voltage to the coil.
  • the movement of the pressure portion can thus be determined by the time pattern of the voltage at the coil.
  • the pressure stroke and the suction stroke do not necessarily have to last for the same period of time.
  • the suction stroke in any case to be performed as quickly as possible, in which respect however care is to be taken to ensure that no cavitation occurs in the pressure chamber.
  • the described drafting of a non-linear system description for the electromagnetic metering pump system makes it possible to use model-based diagnosis methods. For that purpose the state parameters of the system models are evaluated and the pressure in the pump head of the electromagnetic metering pump is determined. The necessary current and position sensors are in that case already installed in the pump system for control purposes so that the information is already available without the structure of the metering pump having to be supplemented. The diagnosis algorithms can then be performed on the basis of the time variation in the state parameters and the pressure in the metering head of the pump.
  • model-based diagnosis of process-side overpressure and the automated pump shut-down can be implemented.
  • Recognition of the valve opening and valve closing times can be effected for example by way of determining and evaluating time gradients of linked state parameters of the system model. A situation involving exceeding or falling below the state gradients can be detected by means of predetermined limits, which leads to a identification of the valve opening and valve closing times.
  • a corresponding pressure-travel graph is shown at the left in FIG. 1 .
  • the associated travel-time graph is shown at the right in FIG. 1 .
  • the associated pressure-travel graph is shown at the left in FIG. 1 . It is traveled in the clockwise direction, beginning at the coordinate origin at which the pressure portion is in position 1 . During the pressure phase the pressure in the metering chamber will initially rise steeply until the pressure is in a position of opening the valve to the pressure line. As soon as the pressure valve is opened the pressure in the metering chamber remains substantially constant. The opening point is identified by reference 2 . From that moment in time which is also shown at the right in FIG. 1 a metering action takes place. With each further movement of the pressure portion metering fluid is pumped into the pressure line.
  • the pressure valve immediately closes and the pressure in the metering chamber falls again.
  • the suction valve opens, connecting the metering chamber to the suction line, and metering fluid is sucked into the metering chamber until the starting position is regained.
  • the valve closing times can be determined from the travel-time graph as they are on the travel maxima of the pressure portion.
  • the time 4 can also be determined in the same way. That determining operation can be effected in each cycle and the result used for a later cycle. In that way changes in the opening times are also detected.
  • Gas bubbles in the hydraulic system, cavitation in the pump head of the metering unit and/or valve opening and valve closing times of the metering units can be diagnosed by comparison of the target and actual trajectories of the individual state parameters. Particularly when a predetermined fault limit is exceeded between the target and actual trajectories that can trigger a warning signal and corresponding measures.
  • FIG. 2 An example is shown in FIG. 2 .
  • the pressure-travel graph is shown at the left and the travel-time graph at the right.
  • the right-hand Figure is identical to the corresponding graph in FIG. 1 .
  • a marked shift in the valve opening times can therefore be used to diagnose the state “air in the metering chamber”.
  • cavitation only the valve opening time 4 ′ and not the valve opening time 2 is shifted so that such a behaviour can be used to diagnose the state “cavitation”.
  • the model-based method presented by virtue of analysis of the individual linked system state parameters, permits a substantially more extensive and higher-grade diagnosis than was previously implemented.
  • model In addition it is possible by means of the model to identify future or actually already existing deviations between the target curve and the actual curve.
  • the model can also be used to calculate the probable influence of a control intervention.
  • FIG. 4 That self-regulating principle is diagrammatically shown in FIG. 4 for clarification purposes. This shows the position of the pressure portion on the Y-axis and time on the X-axis.
  • a target profile used for the closed-loop control is illustrated in a broken line. That target profile corresponds to the desired target profile which is reproduced for comparison in the third cycle as the reference profile.
  • the actual profile will deviate from the target profile.
  • an actual profile is shown in solid line. In that case the deviations between the actual and target profiles are shown more pronounced for clarity than they occur in practice.
  • the difference between the actual profile of the first cycle and the reference profile is then subtracted from the target profile used for the first cycle and the difference is used as the target profile for closed-loop control during the second cycle.
  • the target profile obtained in that way is shown in broken line in the second cycle.
  • the position of the displacer element or the speed and acceleration which can be deduced therefrom of the displacer element and the pressure in the metering chamber which can be determined by way of the force exerted on the delivery fluid by the diaphragm serve as measurement variables or external variables to be determined.
  • the suction line comprises a hose connecting the suction valve to a supply container the hydraulic system can be described in simplified form for the suction stroke, that is to say while the pressure valve is closed and the suction valve is opened, as is shown in FIG. 5 .
  • the suction line comprises a hose of a diameter D S and a hose length L. The hose bridges over a height difference Z.
  • the non-linear Navier-Stokes equations can be simplified if it is assumed that the suction line is of a constant diameter and is not stretchable and that an incompressible fluid is used.
  • the hydraulic parameters are now determined, which on the basis of the model can best describe the measured or determined position of the pressure portion and the measured or determined pressure in the metering chamber.
  • FIGS. 6 a through 6 e using the example of glycerin as the delivery fluid, here each show a hydraulic parameter (dotted line) and the values from the method according to the invention (solid line) in relation to time.
  • the parameters determined by the method according to the invention can then in turn be used together with the physical model produced to determine the force exerted on the pressure portion by the hydraulic system.
  • That information can be used for the closed-loop control according to the invention.
  • the hydraulic model developed can physically reproduce the influence of the hydraulic system and take account of same in the form of a disturbance variable intrusion.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Medical Informatics (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Evolutionary Computation (AREA)
  • Health & Medical Sciences (AREA)
  • Software Systems (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Fluid Mechanics (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Electromagnetic Pumps, Or The Like (AREA)
  • Reciprocating Pumps (AREA)
US14/907,851 2013-08-29 2014-08-21 Method for Determining a Physical Variable in a Positive Displacement Pump Abandoned US20160177937A1 (en)

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DE102013109410.4 2013-08-29
DE102013109410.4A DE102013109410A1 (de) 2013-08-29 2013-08-29 Verfahren zur Bestimmung einer physikalischen Größe in einer Verdrängerpumpe
PCT/EP2014/067816 WO2015028385A1 (de) 2013-08-29 2014-08-21 VERFAHREN ZUR BESTIMMUNG EINER PHYSIKALISCHEN GRÖßE IN EINER VERDRÄNGERPUMPE

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KR (1) KR20160046888A (enExample)
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US20190154030A1 (en) * 2017-11-17 2019-05-23 Artemis Intelligent Power Limited Deducing pressure from reopening angle
EP3591226A1 (en) * 2018-07-06 2020-01-08 Grundfos Holding A/S Metering pump and method for controlling a metering pump
US10737002B2 (en) 2014-12-22 2020-08-11 Smith & Nephew Plc Pressure sampling systems and methods for negative pressure wound therapy
US11191897B2 (en) 2019-03-04 2021-12-07 Eitan Medical Ltd. In cycle pressure measurement
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US20160201657A1 (en) * 2013-08-29 2016-07-14 Prominent Gmbh Method for Improving Metering Profiles of Displacement Pumps
US10737002B2 (en) 2014-12-22 2020-08-11 Smith & Nephew Plc Pressure sampling systems and methods for negative pressure wound therapy
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US11278665B2 (en) * 2016-11-22 2022-03-22 Eitan Medical Ltd. Method for delivering a therapeutic substance
EP3348836A1 (en) * 2017-01-17 2018-07-18 General Electric Company Two-stage reciprocating compressor optimization control system
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USRE50074E1 (en) 2017-03-29 2024-08-06 Samsung Electronics Co., Ltd. Method for managing and controlling external IoT device and electronic device supporting the same
US20190154030A1 (en) * 2017-11-17 2019-05-23 Artemis Intelligent Power Limited Deducing pressure from reopening angle
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EP3981984A1 (en) * 2018-07-06 2022-04-13 Grundfos Holding A/S Metering pump and method for controlling a metering pump
EP3591226A1 (en) * 2018-07-06 2020-01-08 Grundfos Holding A/S Metering pump and method for controlling a metering pump
US11357909B2 (en) 2018-10-05 2022-06-14 Eitan Medical Ltd. Triggering sequence
US11701464B2 (en) 2018-10-05 2023-07-18 Eitan Medical Ltd. Drawing drug from a vial
US11191897B2 (en) 2019-03-04 2021-12-07 Eitan Medical Ltd. In cycle pressure measurement
EP4108916A1 (en) * 2021-06-25 2022-12-28 Grundfos Holding A/S Monitoring method for monitoring the operation of a dosing pump and dosing pump system
US20220412334A1 (en) * 2021-06-25 2022-12-29 Grundfos Holding A/S Monitoring method for monitoring the operation of a dosing pump and dosing pump system
US20240167582A1 (en) * 2022-11-17 2024-05-23 Fisher Controls International Llc Methods and apparatus to analyze valve characteristics

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JP2016530444A (ja) 2016-09-29
EP3039287A1 (de) 2016-07-06
EP3039287B1 (de) 2019-09-25
KR20160046888A (ko) 2016-04-29
CN105492768B (zh) 2019-05-03
WO2015028385A1 (de) 2015-03-05
DE102013109410A1 (de) 2015-03-19
CN105492768A (zh) 2016-04-13
JP6234584B2 (ja) 2017-11-22
CA2921877A1 (en) 2015-03-05
CA2921877C (en) 2021-05-04

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