EP0582625B1 - Process and device for the controlled metering of at least one pourable component - Google Patents

Process and device for the controlled metering of at least one pourable component Download PDF

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Publication number
EP0582625B1
EP0582625B1 EP92909623A EP92909623A EP0582625B1 EP 0582625 B1 EP0582625 B1 EP 0582625B1 EP 92909623 A EP92909623 A EP 92909623A EP 92909623 A EP92909623 A EP 92909623A EP 0582625 B1 EP0582625 B1 EP 0582625B1
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EP
European Patent Office
Prior art keywords
hydraulic
positive displacement
metering
accordance
pressure
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EP92909623A
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German (de)
French (fr)
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EP0582625B2 (en
EP0582625A1 (en
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Hans Willi Meinz
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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
    • F04B11/00—Equalisation of pulses, e.g. by use of air vessels; Counteracting cavitation
    • F04B11/005—Equalisation of pulses, e.g. by use of air vessels; Counteracting cavitation using two or more pumping pistons
    • 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
    • F04B43/06—Pumps having fluid drive
    • F04B43/073—Pumps having fluid drive the actuating fluid being controlled by at least one valve
    • F04B43/0736—Pumps having fluid drive the actuating fluid being controlled by at least one valve with two or more pumping chambers in parallel
    • 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
    • F04B9/00—Piston machines or pumps characterised by the driving or driven means to or from their working members
    • F04B9/08—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid
    • F04B9/10—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being liquid
    • F04B9/109—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being liquid having plural pumping chambers
    • F04B9/111—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being liquid having plural pumping chambers with two mechanically connected pumping members
    • F04B9/115—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being liquid having plural pumping chambers with two mechanically connected pumping members reciprocating movement of the pumping members being obtained by two single-acting liquid motors, each acting in one direction

Definitions

  • the invention relates to a method for the controlled dosing of at least one flowable component by means of a displacement pump unit for each component, which is driven by a dosed hydraulic flow and is formed from two identical displacement pumps, each with an oscillating displacement element Hydraulic space of one positive displacement pump and an outflow line is connected to the hydraulic space of the other positive displacement pump, then the metering line is connected to both hydraulic spaces, then the metering line is connected to the hydraulic space of the other positive displacement pump and the outflow line is connected to the hydraulic space of one positive displacement pump, then the metering line again is connected to both hydraulic spaces and finally at the end of a cycle and thus at the beginning of the next the metering line again with the hydraulic space of one unit
  • the displacement pump and the outflow line are connected to the hydraulic chamber of the other displacement pump, with each displacement pump requiring the outflow to take less time than the dosing and during the dosing.
  • the invention further relates to a method which is particularly suitable for carrying out the method according to the invention Contraption .
  • the large-volume, slow-running pumps used in such cases are mostly based on the oscillating displacement principle.
  • Such a positive displacement pump unit has a large number of maintenance-intensive, wear-prone components, such as Valves and seals that require extensive maintenance.
  • complex flow monitors are generally necessary, which in turn have to be monitored.
  • the object of the present invention is now to provide a method for the controlled metering of at least one flowable component and to provide a device which is particularly suitable for carrying out this method and with which it is possible to meter even media which are difficult to convey in a controlled manner.
  • the method and device are to be self-monitoring, fault-free and maintenance-free, work with high accuracy and reproducibility over a long period of time, and insidious leaks and thus metering errors are to be recorded and documented quantitatively.
  • a reproducible, highly precise dosing requires pulsation- and leak-free delivery. Therefore, an unproblematic hydraulic flow is first generated without pulsation, which can be done without difficulty in the known oil-hydraulic metering devices.
  • the problematic liquid on the other hand, is dosed in a second circuit, which is separated from the oil circuit by oscillating displacers. A volume flow supplied on the hydraulic side thus displaces an equal volume on the medium side.
  • the known electro-hydraulic dosing methods e.g. from the field of servo or proportional valve technology.
  • the metered hydraulic flow is divided in a power distribution unit in such a way that the one displacement pump equipped with an oscillating displacement element and then the other identical displacement pump are alternately driven by this hydraulic flow.
  • the metering pump thus serves as a pressure accumulator for the pump that is not yet metering. Due to the short-term connection of the two hydraulic rooms during the dosing, there is initially a pressure equalization, which results in a certain drop in pressure. With low compressible media and high pressures, this pressure drop is negligibly small (less than 5%, based on the instantaneous value). so that there is already an approximate freedom from pulsations can be spoken.
  • Another advantage of this method is that the filling stroke of the pumps can in principle take place in a shorter time interval than the metering stroke. This saves the necessary time to replace all wear and therefore leakage components of the positive displacement pumps, e.g. Inlet and outlet valves on the metering and hydraulic side, at regular intervals, e.g. undergo a leak test after each pump cycle.
  • the positive displacement pumps e.g. Inlet and outlet valves on the metering and hydraulic side
  • a pre-compression of the metering and hydraulic medium by increasing the hydraulic pressure in the respective hydraulic chamber by a hydraulic pressure source at most to the dosing pressure and that possible changes in the hydraulic pressure in the respective hydraulic chamber are then measured within a defined time interval.
  • This measurement method makes it possible to check the inlet valves of the dosing and hydraulic rooms more precisely.
  • the dosing and hydraulic medium is pre-compressed to the dosing pressure.
  • a pre-compression of the metering and hydraulic medium takes place by increasing the hydraulic pressure in all hydraulic rooms by a hydraulic pressure source and that a possible change in the hydraulic pressure is measured within a defined time interval.
  • the tightness of the oil-hydraulic metering unit can be measured quantitatively by pre-compressing to a defined pressure during the idle times of both positive displacement pumps and then measuring a possible pressure change in a defined time interval. Since the oil-hydraulic metering unit is subject to much less wear than the two positive displacement pumps, such a measurement is not useful for every pump cycle, rather it is sufficient, e.g. routinely take a measurement every time the dosing unit starts.
  • a device in which two identical oscillating displacement pumps, either self-priming or working with a pre-pressure supply, each with a displacement element, are provided, one hydraulic metering unit for each component a leak-tight shut-off device is connected to the two hydraulic chambers of the two positive displacement pumps, at least one hydraulic metering unit is supplied by a hydraulic pressure source, and in each case a leak tightness in the inlet and outlet of the respective metering chamber and hydraulic chamber of each positive displacement pump Shut-off device is arranged, a pressure measuring device is connected to the hydraulic chamber of each positive displacement pump and the positive displacement pumps are provided with a control which coordinates the suction, filling and metering strokes.
  • a particularly simple design is represented by the positive displacement pumps, which work with a pre-pressure supply and consist of only one displacement element, which oscillates between the metering and hydraulic space, and a housing.
  • the displacer elements are hydraulically clamped between the hydraulic and the pumped medium, so that an almost identical pressure level is achieved on both sides when the displacer elements are guided without friction. The freedom from friction is necessary so that no pressure build-up due to starting torque is generated in the changeover points of the displacement elements.
  • the displacement elements are pressurized by a hydraulic metering unit, which consists either of a hydraulic motor with a mechanically coupled servo or stepping motor or a flow meter with an electrically coupled servo or proportional valve.
  • the filling and metering strokes of the two positive displacement pumps are coordinated in time by an electro-hydraulic control.
  • the control has the task of timing the hydraulic lines required to operate the pumps staggered to connect so that there can be no short circuit to the tank.
  • the first and the second pump draws in, in the other end position the second pump doses and the first pump sucks.
  • a start signal must be given to the other displacer.
  • the suction process of the self-priming pump or the filling process of the pump working with pre-pressure supply takes place by connecting the respective hydraulic chamber to the tank.
  • the device can be designed such that the displacement elements are membranes.
  • the use of a diaphragm as a displacer for a pump for dosing problematic media offers itself due to its structural simplicity (low costs) and technical advantages. With the help of membranes, the requirement for leak-free and friction-free sealing of the displacement elements can be met most easily. Membranes are considerably cheaper compared to pistons that are sealed with no leakage and also have the advantage of being leak-free over their entire service life. Since the diaphragm is clamped without differential pressure between two liquids in the pump working with the pre-pressure supply, it is possible to transmit an almost arbitrarily large pressure to the medium to be dosed. In the self-priming version, all the spaces filled with hydraulic fluid of one pump must be short-circuited during the metering stroke in order to avoid a possible differential pressure on the membrane.
  • the device can be designed in such a way that the membranes consist of at least two individual membranes lying one above the other, forming a circumferential clamping point, between each of which there is a gap and that each gap is provided with a leakage drain via a clamping point .
  • the membranes consist of at least two individual membranes lying one above the other, forming a circumferential clamping point, between each of which there is a gap and that each gap is provided with a leakage drain via a clamping point .
  • the device can be designed such that the displacement elements are bellows.
  • Bellows made of austenitic stainless steel are superior to other materials, particularly with abrasive and / or corrosive media.
  • Another advantage of the steel bellows is that they can be welded to both the flange and the bottom, which ensures an optimal seal between the hydraulic and metering spaces.
  • the device can be designed in such a way that the bellows consist of at least two partition walls lying on top of one another, between each of which there is an intermediate space, and that each intermediate space is provided with a leakage derivation via a clamping point.
  • a double or multi-walled design of the bellows allows great elasticity with great flexural rigidity (principle of leaf spring), which results in a larger usable displacement volume of the bellows.
  • Another advantage of a multi-layer steel bellows is the greater safety when leaking. In the event of a bellows break, either the hydraulic or the dosing medium enters the space between the partitions and from there it goes out to either trigger an alarm or shut down the device. In any case, leakage avoidance is activated. before there is a mixture of dosing and Hydraulic medium is coming.
  • the device can be designed such that the shut-off devices located in the inlet and outlet of the metering space are automatic check valves.
  • This version represents a particularly simple constructive solution for the inlet and outlet valves on the dosing medium side.
  • automatic ball check valves are available, which are also suitable for abrasive liquids. Since the ball rotates in the liquid flow, the wear that occurs is distributed over the entire surface of the ball.
  • the device can be designed such that the shut-off devices located in the inlet and outlet of the hydraulic chamber are electromagnetically actuated 2/2 seat valves. In this way, the leakage on the valve side can be completely eliminated, which is absolutely necessary for precise dosing.
  • the hydraulic flows can be controlled very easily individually. In particular, switching the metering or outflow line at different times can be mastered well with the four electromagnetically operated 2/2 seat valves and a corresponding digital control.
  • the device can be designed such that the 2/2-seat valves are open in the de-energized state.
  • This version provides additional security in the event of a power failure or cable break, since in such cases it opens all valves by spring force and prevents the displacement elements from being destroyed by passing the end positions.
  • the device can be designed in such a way that in addition to the 2/2 seat valves a 3/2-proportional pressure control valve is provided which, when the metering line and the outflow line are switched by means of the 2/2-way valves, causes a constant change in the volume flow and thus the pressure reduction or build-up over an adjustable period of time. Possible pressure surges in the switchover points are reduced in this way, since the oil flow is not suddenly accelerated or decelerated. Pressure surges caused by the rapid switching of the metering and discharge lines can almost be eliminated by this measure.
  • the 3/2-proportional pressure control valve is used to achieve additional pre-compression in the case of highly compressible dosing media, since in this case the pre-compression is no longer sufficient due to the pressure equalization of the pumps dosing together.
  • the pre-compression pressure is raised to the pressure level of the dosing pressure in order to achieve a theoretically complete absence of pulsation.
  • the device can be designed such that the pressure measuring device consists of an electrical pressure sensor.
  • the pressure measuring device consists of an electrical pressure sensor.
  • the pressure measurement by a pressure sensor of the other positive displacement pump is required. Different leak tests are carried out with the same pressure sensor.
  • the device can be designed in such a way that a personal computer or a programmable logic controller is provided which evaluates the pressure curve during the leak test.
  • the pressure curve as a function of time must be recorded and compared with stored values. This makes it possible to assess the tightness of the positive displacement pumps.
  • the use of a PLC or PC is ideal for this task, especially because such devices are used to control the displacement pumps anyway required are.
  • the device can be designed such that at least one inductive proximity switch controlled by the position of the displacement element is arranged in each hydraulic chamber.
  • a position control of the displacers is necessary.
  • the use of inductive proximity switches is particularly easy, since, unlike the displacement sensors, they do not require an additional electronic evaluation unit, but are just as easy to use as mechanical limit switches.
  • the position of the displacers is checked by a pressure-resistant inductive proximity switch, which monitors a groove on a control rod attached to the displacers.
  • the device can be designed such that the inductive proximity switches are switched through in the unactuated state.
  • the failure of an inductive proximity switch e.g. due to a cable break
  • the device can be designed such that at least one inductive displacement sensor controlled by the position of the displacement element is arranged in each hydraulic chamber.
  • the advantage of the inductive displacement transducer lies in its thermal resilience and in the fact that it has the position which can continuously detect displacement elements.
  • the device can be designed such that the position of the displacement element is determined by volumetric displacement measurement by means of the hydraulic metering unit.
  • position sensors can be dispensed with in the displacement pumps if the metered amount of oil is used as a measure of the distance traveled by the displacement element.
  • the disadvantage here is that the position of the displacer cannot be determined after interruptions and other faults.
  • the device can be designed such that the control of the displacement pump unit is a microprocessor control (for example a programmable logic controller or personal computer).
  • the control of the device according to the invention is of considerable importance. It can basically be done pneumatically, hydraulically or electrically.
  • a small, compact programmable logic controller (PLC) is already available with a positive displacement pump unit equipped with two inductive proximity switches and four solenoid valves.
  • the PLC has the advantage of great flexibility. Processes can be optimally matched to the individual requirements.
  • the additional possibility of error detection and diagnosis means that incorrect operation can be intercepted in good time and the maintenance time can be drastically reduced. Due to the falling prices for personal computers, economical use instead of a PLC makes sense for less complex processes, especially then. if the process flows are to be visualized and documented. This enables maintenance personnel to track all machine-relevant data on the screen or on the printer. Furthermore, an interface to a higher-level master computer for central measurement data acquisition is possible.
  • the embodiment according to the drawing has two identical mirror-symmetrical, not self-priming displacement pumps 1, 2, each of which is located in a housing 3, 4.
  • the two positive displacement pumps 1, 2 each consist of a hydraulic chamber 5, 6 and a metering chamber 7, 8, a spherical dome-shaped membrane 9, 10, each of which is clamped on their, between a hydraulic chamber 5, 6 and a metering chamber 7, 8 the hydraulic chamber 5,6 facing side carries a control rod 11,12.
  • the control rod 11, 12 continuously outputs a signal to an inductive proximity switch 13, 14.
  • the changeover process is initiated in the absence of a signal by the inductive proximity switches 13, 14 using an electrical control unit (not shown) four 2/2-way valves 15, 16 , 17, 18 de-energize.
  • the two 2/2-way valves 15, 16 connect the two hydraulic chambers 5, 6 with a metering line 19, so that both displacement pumps 1, 2 simultaneously deliver for a time determined by the electrical control (not shown).
  • the start of the metering stroke of the displacement pump, which initiated the reversal process, is thus determined by the lack of a signal from the inductive proximity switch 13 or 14.
  • the end of the metering stroke of the displacement pump that initiated the reversal process is determined by the electrical control unit (not shown) with a time delay as a function of the delivery capacity of the displacement pumps 1, 2.
  • the filling stroke begins at the same time as the end of the dosing stroke.
  • the displacement pump pauses between the end of the filling stroke and the start of the dosing stroke. that is, it is neither connected to the discharge line 20 nor to the metering line 19.
  • the leakage tests can now be carried out according to the method according to the invention, for what purpose the pressure sensors 21, 22 and the 3/2-proportional pressure control valve 23 are used.
  • the spring-loaded check valves 24, 25 open and close at the end of the filling stroke.
  • a hydraulic metering unit 28 which consists of a hydraulic motor 29 with a mechanically coupled servo or stepping motor 30, the necessary pre-pressure for the hydraulic motor 29 coming from a hydraulic pressure source 31, which is also the 3/2 Proportional pressure control valve 23 supplied with hydraulic pressure.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Basic Packing Technique (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

In a process for the controlled metering of at least one pourable component, two force pumps (1, 2) driven by a smooth hydraulic current, each with an oscillating force component (9, 10), are used whereby the hydraulic current is divided in a current divider in such a way that one force pump, then both together and then the other identical force pump are driven alternately by this hydraulic current. The volume flow from the force pumps (1, 2) is also smooth and also free of leaks owing to the sealing tests performed on a force pump (1, 2) during the inoperative period. A device for implementing the process is also described.

Description

Die Erfindung betrifft ein Verfahren zur kontrollierten Dosierung mindestens einer fließfähigen Komponente mittels einer von einem dosierten Hydraulikstrom angetriebenen, aus zwei gleichen Verdrängerpumpen mit je einem oszillierenden Verdrängerelement gebildeten Verdrängerpumpeneinheit für jede Komponente, wobei eine Dosierleitung, die den dosierten Hydraulikstrom führt, über eine Stromverteilereinheit mit dem Hydraulikraum der einen Verdrängerpumpe und eine Abströmleitung mit dem Hydraulikraum der anderen Verdrängerpumpe verbunden wird, danach die Dosierleitung mit beiden Hydraulikräumen verbunden wird, dann die Dosierleitung mit dem Hydraulikraum der anderen Verdrängerpumpe und die Abströmleitung mit dem Hydraulikraum der einen Verdrängerpumpe verbunden wird, anschließend die Dosierleitung wieder mit beiden Hydraulikräumen verbunden wird und schließlich am Ende eines Zyklus und damit am Anfang des nächsten die Dosierleitung erneut mit dem Hydraulikraum der einen Verdrängerpumpe und die Abströmleitung mit dem Hydraulikraum der anderen Verdrängerpumpe verbunden wird, wobei bei jeder Verdrängerpumpe das Abströmen kürzere Zeit beansprucht als das Dosieren und während des Dosierens erfolgt.The invention relates to a method for the controlled dosing of at least one flowable component by means of a displacement pump unit for each component, which is driven by a dosed hydraulic flow and is formed from two identical displacement pumps, each with an oscillating displacement element Hydraulic space of one positive displacement pump and an outflow line is connected to the hydraulic space of the other positive displacement pump, then the metering line is connected to both hydraulic spaces, then the metering line is connected to the hydraulic space of the other positive displacement pump and the outflow line is connected to the hydraulic space of one positive displacement pump, then the metering line again is connected to both hydraulic spaces and finally at the end of a cycle and thus at the beginning of the next the metering line again with the hydraulic space of one unit The displacement pump and the outflow line are connected to the hydraulic chamber of the other displacement pump, with each displacement pump requiring the outflow to take less time than the dosing and during the dosing.

Ein solches Verfahren ist grundsätzlich mit einer Pumpe durchführbar, wie sie in EP-A-0 250 026 beschrieben ist.In principle, such a method can be carried out with a pump as described in EP-A-0 250 026.

Ferner betrifft die Erfindung eine zur Durchführung des erfindungsgemäßen Verfahrens besonders gegeeignete Vorrichtung .The invention further relates to a method which is particularly suitable for carrying out the method according to the invention Contraption .

In den verschiedensten Gebieten der Technik ist es immer wieder erforderlich, ein fließfähiges Medium mittels Pumpen unter Druck hochgenau zu dosieren. Sowohl für die bekannten Hydraulikflüssigkeiten als auch für viele andere homogene Fluide kann dies zufriedenstellend mit bekannten Vorrichtungen gelöst werden.In various areas of technology, it is always necessary to meter a flowable medium with high precision by means of pumps under pressure. Both for the known hydraulic fluids and for many other homogeneous ones Fluids this can be solved satisfactorily with known devices.

Schwierigkeiten treten aber immer dann auf, wenn das zu dosierende Medium schwierig zu handhaben ist, weil z.B. das fließfähige Medium aus einem oder mehreren abrasiven Feststoffen, z.B. Pigmenten, zusammengesetzt ist, das Medium außerdem zum Auskristallisieren oder Verkleben neigt, so daß die verwendeten Dosierpumpen durch Verschleiß bzw. Leckagen bereits nach kurzer Zeit undefinierte Dosierfehler aufweisen.However, difficulties always arise when the medium to be dosed is difficult to handle, e.g. because the flowable medium from one or more abrasive solids, e.g. Pigments, is composed, the medium also tends to crystallize or stick, so that the metering pumps used have wear and leakage after a short time undefined metering errors.

Die in solchen Fällen eingesetzten großvolumigen langsamlaufenden Pumpen basieren meistens auf dem oszillierenden Verdrängerprinzip. Eine solche Verdrängerpumpeneinheit besitzt eine große Anzahl an wartungsintensiven, verschleißbehafteten Bauteilen, wie z.B. Ventile und Dichtungen, die eine aufwendige Instandhaltung erfordern. Um mit solchen Dosierpumpen über eine längere Zeit reproduzierbar genau dosieren zu können, sind in der Regel aufwendige Durchflußüberwachungen notwendig, die ihrerseits wiederum überwacht werden müssen.The large-volume, slow-running pumps used in such cases are mostly based on the oscillating displacement principle. Such a positive displacement pump unit has a large number of maintenance-intensive, wear-prone components, such as Valves and seals that require extensive maintenance. In order to be able to meter with such metering pumps reproducibly over a long period of time, complex flow monitors are generally necessary, which in turn have to be monitored.

Die Aufgabe der vorliegenden Erfindung besteht nun darin, ein Verfahren zur kontrollierten Dosierung mindestens einer fließfähigen Komponente anzugeben sowie eine zur Durchführung dieses Verfahrens besonders geeignete Vorrichtung zu schaffen, mit dem bzw. der es möglich ist, auch schwierig zu fördernde Medien kontrolliert zu dosieren. Dabei sollen Verfahren und Vorrichtung selbstüberwachend störungs- und wartungsfrei über lange Zeit hochgenau und reproduzierbar arbeiten und einschleichend auftretende Undichtigkeiten und damit Dosierfehler quantitativ erfassen und dokumentieren.The object of the present invention is now to provide a method for the controlled metering of at least one flowable component and to provide a device which is particularly suitable for carrying out this method and with which it is possible to meter even media which are difficult to convey in a controlled manner. The method and device are to be self-monitoring, fault-free and maintenance-free, work with high accuracy and reproducibility over a long period of time, and insidious leaks and thus metering errors are to be recorded and documented quantitatively.

Diese Aufgabe wird erfindungsgemäß bei einem Verfahren der eingangs erwähnten Art dadurch gelöst. daß in den Ruhezeiten der jeweiligen Verdrängerpumpe, in der sie weder mit der Abströmleitung noch mit der Dosierleitung verbunden ist, mögliche Änderungen des Hydraulikdrucks in dem jeweiligen Hydraulikraum innerhalb eines definierten Zeitintervalls gemessen werden.This object is achieved according to the invention in a method of the type mentioned at the outset. that in the rest of the respective positive displacement pump, in which it is neither with the discharge line is still connected to the metering line, possible changes in the hydraulic pressure in the respective hydraulic space are measured within a defined time interval.

Eine reproduzierbare hochgenaue Dosierung setzt ein pulsations- und leckagefreies Fördern voraus. Deshalb wird also zunächst ein unproblematischer Hydraulikstrom pulsationsfrei erzeugt, was ohne Schwierigkeiten in den bekannten ölhydraulischen Dosiervorrichtungen erfolgen kann. Die Dosierung der problematischen Flüssigkeit dagegen erfolgt in einem zweiten Kreislauf, der durch oszillierende Verdränger von dem Ölkreislauf getrennt ist. Ein auf der Hydraulikseite zugeführter Volumenstrom verdrängt somit auf der Mediumseite ein gleich großes Volumen. Durch die Verlagerung des Dosierproblems auf die hydraulische Seite können somit auch für schwerförderbare Medien die bekannten elektrohydraulischen Dosierverfahren, z.B. aus dem Bereich der Servo- oder Proportionalventiltechnik, eingesetzt werden.A reproducible, highly precise dosing requires pulsation- and leak-free delivery. Therefore, an unproblematic hydraulic flow is first generated without pulsation, which can be done without difficulty in the known oil-hydraulic metering devices. The problematic liquid, on the other hand, is dosed in a second circuit, which is separated from the oil circuit by oscillating displacers. A volume flow supplied on the hydraulic side thus displaces an equal volume on the medium side. By shifting the dosing problem to the hydraulic side, the known electro-hydraulic dosing methods, e.g. from the field of servo or proportional valve technology.

Zum Zweck der Mediumdosierung wird der dosierte Hydraulikstrom in einer Stromverteilereinheit geteilt und zwar derart, daß abwechselnd die eine mit einem oszillierenden Verdrängerelement ausgestattete Verdrängerpumpe und danach die andere baugleiche Verdrängerpumpe von diesem Hydraulikstrom angetrieben wird. Bei diesem Verfahren sind Pulsationen weitgehend eliminiert, weil vor jedem Dosierhub grundsätzlich eine Vorkompression des Dosiermediums stattfindet, indem kurz vor Beendigung des Dosierhubes der einen verdrängerpumpe bereits die andere Pumpe zu dosieren beginnt. Die dosierende Pumpe dient somit als Druckspeicher für die noch nicht dosierende Pumpe. Durch die kurzzeitige Verbindung der beiden Hydraulikräume während des gemeinsamen Dosierens erfolgt zunächst ein Druckausgleich, der einen gewissen Druckeinbruch zur Folge hat. Bei wenig kompressiblen Medien und hohen Drücken ist dieser Druckeinbruch vernachlässigbar klein (kleiner 5%, bezogen auf den Momentanwert). so daß bereits von einer angenäherten Pulsationsfreiheit gesprochen werden kann.For the purpose of medium metering, the metered hydraulic flow is divided in a power distribution unit in such a way that the one displacement pump equipped with an oscillating displacement element and then the other identical displacement pump are alternately driven by this hydraulic flow. With this method, pulsations are largely eliminated because, prior to each metering stroke, the metering medium in principle is precompressed by the other pump already starting to meter shortly before the metering stroke ends. The metering pump thus serves as a pressure accumulator for the pump that is not yet metering. Due to the short-term connection of the two hydraulic rooms during the dosing, there is initially a pressure equalization, which results in a certain drop in pressure. With low compressible media and high pressures, this pressure drop is negligibly small (less than 5%, based on the instantaneous value). so that there is already an approximate freedom from pulsations can be spoken.

Ein weiterer Vorteil dieses Verfahrens ist, daß der Füllhub der Pumpen grundsätzlich in einem kürzeren Zeitintervall erfolgen kann als der Dosierhub. Dadurch wird die notwendige Zeit gewonnen, um alle verschleiß- und damit leckage-behafteten Bauteile der Verdrängerpumpen, wie z.B. Ein- und Ausgangsventile auf der Dosier- und Hydraulikseite, in regelmäßigen Intervallen, z.B. nach jedem Pumpenzyklus, einer Dichtigkeitsprüfung zu unterziehen.Another advantage of this method is that the filling stroke of the pumps can in principle take place in a shorter time interval than the metering stroke. This saves the necessary time to replace all wear and therefore leakage components of the positive displacement pumps, e.g. Inlet and outlet valves on the metering and hydraulic side, at regular intervals, e.g. undergo a leak test after each pump cycle.

Dies erfolgt in der Art und Weise, daß während der Ruhezeiten der jeweiligen Verdrängerpumpe die Druckänderungen in dem jeweiligen Hydraulikraum mittels elektrischer Drucksensoren gemessen und ausgewertet werden, wobei mogliche Druckänderungen ein Maß für die Dichtigkeit der Stromverteilereinheit, der Ein- und Ausgangsventile der Verdrängerpumpen sowie für andere evt. vorhandene Dichtungsstellen (z.B. Kolbenringe) innerhalb der Verdrängerpumpen darstellen.This is done in such a way that the pressure changes in the respective hydraulic chamber are measured and evaluated by means of electrical pressure sensors during the idle times of the respective positive displacement pump, with possible pressure changes being a measure of the tightness of the power distribution unit, the inlet and outlet valves of the positive displacement pumps and others Show any sealing points (e.g. piston rings) within the positive displacement pumps.

Gemäß einem weiteren Vorschlag der Erfindung ist vorgesehen, daß in den Ruhezeiten der jeweiligen Verdrängerpumpe, in der sie weder mit der Abströmleitung noch mit der Dosierleitung verbunden ist, eine Vorkompression des Dosier- und Hydraulikmediums durch Erhöhung des Hydraulikdrucks in dem jeweiligen Hydraulikraum durch eine Hydraulikdruckquelle bis maximal zum Dosierdruck erfolgt und daß anschließend mögliche Änderungen des Hydraulikdrucks in dem jeweiligen Hydraulikraum innerhalb eines definierten Zeitintervalls gemessen werden. Diese Mäßmethode macht eine genauere Überprüfung der Eingangsventile der Dosier- und der Hydraulikräume möglich. Außerdem wird das Dosier- und Hydraulikmedium auf den Dosierdruck vorkomprimiert. Bei stark kompressiblen Dosiermedien ist eine zusätzliche Vorkompression notwendig, da in diesem Fall die Vorkompression durch den Druckausgleich der gemeinsam fördernden Pumpen nicht mehr ausreicht. Im Idealfall wird der vorkompressionsdruck bis auf das Druckniveau des Dosierdrucks angehoben, um eventuelle Drucksprünge beim Umschalten von einer Pumpe zur anderen zu vermeiden. Mit dieser Methode kann eine Pulsationsfreiheit von ca. 1%, bezogen auf den Momentanwert, erreicht werden.According to a further proposal of the invention it is provided that in the rest times of the respective positive displacement pump, in which it is not connected to the outflow line or to the metering line, a pre-compression of the metering and hydraulic medium by increasing the hydraulic pressure in the respective hydraulic chamber by a hydraulic pressure source at most to the dosing pressure and that possible changes in the hydraulic pressure in the respective hydraulic chamber are then measured within a defined time interval. This measurement method makes it possible to check the inlet valves of the dosing and hydraulic rooms more precisely. In addition, the dosing and hydraulic medium is pre-compressed to the dosing pressure. In the case of highly compressible dosing media, additional pre-compression is necessary, since in this case the pre-compression is no longer sufficient due to the pressure equalization of the pumps that are pumping together. Ideally, the pre-compression pressure raised to the pressure level of the dosing pressure in order to avoid possible pressure jumps when switching from one pump to another. With this method, a pulsation freedom of approx. 1%, based on the instantaneous value, can be achieved.

Gemäß einem weiteren Vorschlag der Erfindung ist vorgesehen, daß in den Ruhezeiten beider Verdrängerpumpen eine Vorkompression des Dosier- und Hydraulikmediums durch Erhöhung des Hydraulikdrucks in allen Hydraulikräumen durch eine Hydraulikdruckquelle erfolgt und daß eine mögliche Änderung des Hydraulikdrucks innerhalb eines definierten Zeitintervalls gemessen wird. Mit dieser Meßmethode kann die Dichtigkeit der ölhydraulischen Dosiereinheit quantitativ erfaßt werden, indem in den Ruhezeiten beider Verdrängerpumpen auf einen definierten Druck vorkomprimiert und anschließend in einem definierten Zeitintervall eine mögliche Druckänderung gemessen wird. Da die ölhydraulische Dosiereinheit einem weit geringeren Verschleiß als die beiden Verdrängerpumpen ausgesetzt ist, ist eine solche Messung nicht bei jedem Pumpenzyklus sinnvoll, vielmehr ist es ausreichend, z.B. routinemäßig bei jedem Start der Dosiereinheit, eine Messung durchzuführen.According to a further proposal of the invention it is provided that during the rest times of both positive displacement pumps, a pre-compression of the metering and hydraulic medium takes place by increasing the hydraulic pressure in all hydraulic rooms by a hydraulic pressure source and that a possible change in the hydraulic pressure is measured within a defined time interval. With this measuring method, the tightness of the oil-hydraulic metering unit can be measured quantitatively by pre-compressing to a defined pressure during the idle times of both positive displacement pumps and then measuring a possible pressure change in a defined time interval. Since the oil-hydraulic metering unit is subject to much less wear than the two positive displacement pumps, such a measurement is not useful for every pump cycle, rather it is sufficient, e.g. routinely take a measurement every time the dosing unit starts.

Zur Durchführung des vorstehenden Verfahrens und damit zur kontrollierten Dosierung mindestens einer fließfähigen Komponente ist erfindungsgemäß eine Vorrichtung vorgesehen, bei der je Komponente zwei gleiche, entweder selbstansaugende oder mit Vordruckzuführung arbeitende oszillierende Verdrängerpumpen mit jeweils einem Verdrängerelement vorgesehen sind, je Komponente jeweils eine hydraulische Dosiereinheit über jeweils eine leckagedichte Absperrvorrichtung an die beiden Hydraulikräume der beiden Verdrängerpumpen angeschlossen ist, mindestens eine hydraulische Dosiereinheit durch eine Hydraulikdruckquelle versorgt wird, im Ein- und Ausgang des jeweiligen Dosierraumes und Hydraulikraumes jeder Verdrängerpumpe jeweils eine leckagedichte Absperrvorrichtung angeordnet ist, am Hydraulikraum jeder Verdrängerpumpe eine Druckmeßeinrichtung angeschlossen ist und die Verdrängerpumpen mit einer die Saug- bzw. Füll- und Dosierhübe zeitlich koordinierenden Steuerung versehen sind.In order to carry out the above method and thus for the controlled metering of at least one flowable component, a device is provided according to the invention, in which two identical oscillating displacement pumps, either self-priming or working with a pre-pressure supply, each with a displacement element, are provided, one hydraulic metering unit for each component a leak-tight shut-off device is connected to the two hydraulic chambers of the two positive displacement pumps, at least one hydraulic metering unit is supplied by a hydraulic pressure source, and in each case a leak tightness in the inlet and outlet of the respective metering chamber and hydraulic chamber of each positive displacement pump Shut-off device is arranged, a pressure measuring device is connected to the hydraulic chamber of each positive displacement pump and the positive displacement pumps are provided with a control which coordinates the suction, filling and metering strokes.

Eine besonders einfache Ausführung stellen die mit Vordruckzuführung arbeitenden Verdrängerpumpen dar, die nur aus jeweils einem zwischen Dosier- und Hydraulikraum oszillierenden Verdrängerelement und einem Gehäuse bestehen. Die Verdrängerelemente sind dabei zwischen Hydraulik- und Fördermedium hydraulisch eingespannt, so daß sich auf beiden Seiten bei reibungsfreier Führung der Verdrängerelemente ein nahezu gleiches Druckniveau einstellt. Die Reibungsfreiheit ist notwendig, um in den Umschaltpunkten der Verdrängerelemente keinen Druckaufbau durch Anfahrmomente zu erzeugen. Die Druckbeaufschlagung der Verdrängerelemente erfolgt durch eine hydraulische Dosiereinheit, die entweder aus einem Hydraulikmotor mit mechanisch gekoppeltem Servo- bzw. Schrittmotor oder einem Durchflußmeßgerät mit elektrisch gekoppeltem Servo- bzw. Proportionalventil besteht. In jedem dieser Fälle ist eine verschleißarme, hochgenaue Dosierung möglich, wobei der notwendige Vordruck aus einer Hydraulikdruckquelle stammt. Werden zwei oder mehrere Vorrichtungen nach der Erfindung eingesetzt, ist durch eine elektrische Kopplung der jeweiligen elektrischen Sollwertgeber (Servo- bzw. Schrittmotor und Servo- bzw. Proportionalventil) eine zeitsynchrone Zwei- bzw. Mehrkomponentendosierung möglich, wobei sowohl das Dosierverhältnis als auch Größe und Zeitdauer des auszutragenden Volumenstromes beliebig wählbar sind. Die Ventile der Verdrängerpumpen im Ein- und Ausgang des jeweiligen Dosier- und Hydraulikraumes sind verschleißarme Sitzventile, die in den Ruhezeiten der Verdrängerpumpen der im Verfahren beschriebenen Dichtigkeitsprüfung unterzogen werden, wozu die an jedem Hydraulikraum angeschlossene Druckmeßeinrichtung dient. Die Saug-bzw. Füll- und Dosierhübe der beiden Verdrängerpumpen werden durch eine elektrohydraulische Steuerung zeitlich koordiniert. Die Steuerung besitzt dabei die Aufgabe, die zum Betrieb der Pumpen erforderlichen Hydraulikleitungen zeitlich versetzt so zu verbinden, daß kein Kurzschluß zum Tank entstehen kann. In der einen Endstellung dosiert die erste und die zweite Pumpe saugt an, in der anderen Endstellung dosiert die zweite Pumpe und die erste Pumpe saugt an. Jeweils vor Ende eines Dosierhubes muß ein Startsignal an den anderen Verdränger abgegeben werden. Sobald eine Pumpe ihren Dosierhub beendet hat, erfolgt bei der selbstansaugenden Pumpe der Saug- bzw. bei der mit Vordruckzuführung arbeitenden Pumpe der Füllvorgang, indem der jeweilige Hydraulikraum mit dem Tank verbunden wird.A particularly simple design is represented by the positive displacement pumps, which work with a pre-pressure supply and consist of only one displacement element, which oscillates between the metering and hydraulic space, and a housing. The displacer elements are hydraulically clamped between the hydraulic and the pumped medium, so that an almost identical pressure level is achieved on both sides when the displacer elements are guided without friction. The freedom from friction is necessary so that no pressure build-up due to starting torque is generated in the changeover points of the displacement elements. The displacement elements are pressurized by a hydraulic metering unit, which consists either of a hydraulic motor with a mechanically coupled servo or stepping motor or a flow meter with an electrically coupled servo or proportional valve. In each of these cases, low-wear, high-precision metering is possible, with the necessary pre-pressure coming from a hydraulic pressure source. If two or more devices according to the invention are used, time-synchronous two- or multi-component metering is possible by means of an electrical coupling of the respective electrical setpoint device (servo or stepper motor and servo or proportional valve), the metering ratio as well as size and duration being possible of the volume flow to be discharged can be selected as desired. The valves of the displacement pumps in the inlet and outlet of the respective metering and hydraulic chamber are low-wear seat valves which are subjected to the leak test described in the procedure during the rest times of the displacement pumps, for which the pressure measuring device connected to each hydraulic chamber is used. The suction or. The filling and metering strokes of the two positive displacement pumps are coordinated in time by an electro-hydraulic control. The control has the task of timing the hydraulic lines required to operate the pumps staggered to connect so that there can be no short circuit to the tank. In the one end position the first and the second pump draws in, in the other end position the second pump doses and the first pump sucks. Before the end of a dosing stroke, a start signal must be given to the other displacer. As soon as a pump has ended its dosing stroke, the suction process of the self-priming pump or the filling process of the pump working with pre-pressure supply takes place by connecting the respective hydraulic chamber to the tank.

Bei einer zum Stand der Technik in Betracht gezogenen Pumpe (EP-A-0 250 026) ist abweichend vom Erfindungsvorschlag eine Druckmeßeinrichtung nicht vorgesehen. Auch eine leckagedichte Absperrvorrichtung wird dort nicht offenbart. Ganz im Gegenteil gestattet nach dieser Vorveröffentlichung das Steuerventil in der Mittellage einen Druckausgleich der Hydraulikräume.In a pump considered in relation to the prior art (EP-A-0 250 026), deviating from the proposal of the invention, a pressure measuring device is not provided. A leak-tight shut-off device is also not disclosed there. On the contrary, according to this prior publication, the control valve in the middle position allows pressure equalization of the hydraulic spaces.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die Verdrängerelemente Membranen sind. Der Einsatz einer Membran als Verdränger für eine Pumpe zur Dosierung von problematischen Medien bietet sich aufgrund ihrer baulichen Einfachheit (geringe Kosten) sowie technischer Vorteile an. Mit Hilfe von Membranen läßt sich die Forderung nach leckage- und reibungsfreier Abdichtung der Verdrängerelemente am leichtesten erfüllen. Membranen sind im Vergleich zu entsprechend leckagefrei abgedichteten Kolben erheblich preiswerter und besitzen außerdem den Vorteil der Leckagefreiheit über ihre gesamte Lebensdauer. Da bei der mit Vordruckzuführung arbeitenden Pumpe die Membran ohne Differenzdruck zwischen zwei Flüssigkeiten eingespannt wird, ist es möglich, einen fast beliebig großen Druck auf das zu dosierende Medium zu übertragen. Bei der selbstansaugenden Ausführung müssen alle mit Hydraulikflüssigkeit gefüllten Räume jeweils einer Pumpe während des Dosierhubes kurzgeschlossen sein, um einen möglichen Differenzdruck an der Membran zu vermeiden.According to a further proposal of the invention, the device can be designed such that the displacement elements are membranes. The use of a diaphragm as a displacer for a pump for dosing problematic media offers itself due to its structural simplicity (low costs) and technical advantages. With the help of membranes, the requirement for leak-free and friction-free sealing of the displacement elements can be met most easily. Membranes are considerably cheaper compared to pistons that are sealed with no leakage and also have the advantage of being leak-free over their entire service life. Since the diaphragm is clamped without differential pressure between two liquids in the pump working with the pre-pressure supply, it is possible to transmit an almost arbitrarily large pressure to the medium to be dosed. In the self-priming version, all the spaces filled with hydraulic fluid of one pump must be short-circuited during the metering stroke in order to avoid a possible differential pressure on the membrane.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die Membranen aus mindestens zwei aufeinanderliegenden, eine umlaufende Einspannstelle bildenden Einzelmembranen bestehen, zwischen denen sich jeweils ein Zwischenraum befindet und daß jeder Zwischenraum über eine Einspannstelle mit jeweils einer Leckage-Ableitung versehen ist. Beim Einsatz von hydrauiiscn beaufschlagten Membranpumpen ist es für den Anwender von größter Bedeutung, einen Membranbruch rechtzeitig signalisiert zu bekommen, damit es nicht zum Ausfall der gesamten Pumpeneinheit kommen kann. Insbesondere die durch Membranbruch verursachte Vermischung des Dosiermediums mit der Hydraulikflüssigkeit stellt für den Anwender den am meisten gefürchteten Störfall dar. Eine Membranbruchmeldung ist möglich durch den Einsatz einer Mehrlagenmembran, wobei der Zwischenraum durch eine Leckageüberwachung abgefragt werden kann.According to a further proposal of the invention, the device can be designed in such a way that the membranes consist of at least two individual membranes lying one above the other, forming a circumferential clamping point, between each of which there is a gap and that each gap is provided with a leakage drain via a clamping point . When using hydraulic It is of the utmost importance for the user to receive a diaphragm rupture in good time so that the entire pump unit cannot fail. In particular, the mixing of the dosing medium with the hydraulic fluid caused by the diaphragm rupture represents the most feared accident for the user. A diaphragm rupture report is possible through the use of a multi-layer diaphragm, whereby the gap can be queried by leakage monitoring.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die Verdrängerelemente Faltenbälge sind. Faltenbälge aus austenitischem Edelstahl sind besonders bei abrasiven und/oder korrosiven Medien anderen Werkstoffen überlegen. Ein weiterer Vorteil der Faltenbälge aus Stahl besteht darin, daß sie sowohl am Flansch als auch am Boden geschweißt werden können, was eine optimale Abdichtung zwischen Hydraulik- und Dosierraum gewährleistet.According to a further proposal of the invention, the device can be designed such that the displacement elements are bellows. Bellows made of austenitic stainless steel are superior to other materials, particularly with abrasive and / or corrosive media. Another advantage of the steel bellows is that they can be welded to both the flange and the bottom, which ensures an optimal seal between the hydraulic and metering spaces.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die Faltenbälge aus mindestens zwei aufeinanderliegenden Trennwänden bestehen, zwischen denen sich jeweils ein Zwischenraum befindet, und daß jeder Zwischenraum über eine Einspannstelle mit jeweils einer Leckage-Ableitung versehen ist. Eine doppel- bzw. mehrwandige Ausführung des Faltenbalges erlaubt eine große Elastizität bei gleichzeitig großer Biegesteifigkeit (Prinzip Blattfeder), was ein größeres nutzbares Verdrängungsvolumen des Balges zur Folge hat. Ein weiterer Vorteil eines mehrlagigen Stahlbalges ist die größere Sicherheit beim undichtwerden. Im Falle eines Faltenbalgbruches tritt entweder das Hydraulik- oder das Dosiermedium in den Zwischenraum zwischen den Trennwänden ein und gelangt von dort nach außen, um entweder einen Alarm auszulösen oder die Vorrichtung stillzusetzen. In jedem Fall wird die Leckage-Meidung aktiv. bevor es zu einer Vermischung von Dosier- und Hydraulikmedium kommt.According to a further proposal of the invention, the device can be designed in such a way that the bellows consist of at least two partition walls lying on top of one another, between each of which there is an intermediate space, and that each intermediate space is provided with a leakage derivation via a clamping point. A double or multi-walled design of the bellows allows great elasticity with great flexural rigidity (principle of leaf spring), which results in a larger usable displacement volume of the bellows. Another advantage of a multi-layer steel bellows is the greater safety when leaking. In the event of a bellows break, either the hydraulic or the dosing medium enters the space between the partitions and from there it goes out to either trigger an alarm or shut down the device. In any case, leakage avoidance is activated. before there is a mixture of dosing and Hydraulic medium is coming.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die im Ein- und Ausgang des Dosierraumes befindlichen Absperrvorrichtungen selbsttätige Rückschlagventile sind. Diese Ausführung stellt eine besonders einfache konstruktive Lösung der Ein- und Auslaßventile auf der Dosiermediumseite dar. Für kleine Nennweiten und für eine relativ geringe Hubfrequenz bieten sich selbsttätige Kugelrückschlagventile an, die sich auch für abrasive Flüssigkeiten eignen. Da sich die Kugel im Flüssigkeitsstrom dreht, verteilt sich der auftretende Verschleiß auf die gesamte Kugeloberfläche.According to a further proposal of the invention, the device can be designed such that the shut-off devices located in the inlet and outlet of the metering space are automatic check valves. This version represents a particularly simple constructive solution for the inlet and outlet valves on the dosing medium side. For small nominal widths and for a relatively low stroke frequency, automatic ball check valves are available, which are also suitable for abrasive liquids. Since the ball rotates in the liquid flow, the wear that occurs is distributed over the entire surface of the ball.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die im Ein- und Ausgang des Hydraulikraumes befindlichen Absperrvorrichtungen elektromagnetisch betätigte 2/2-Sitzventile sind. Auf diese Weise läßt sich die Leckage auf der Ventilseite gänzlich eliminieren, was zum genauen Dosieren absolut notwendig ist. In Verbindung mit einer digitalen Mikroprozessorsteuerung lassen sich auf diese Art und Weise die Hydraulikströme sehr einfach einzeln ansteuern. Insbesondere das zeitlich versetzte Umschalten der Dosier- bzw. Abströmleitung läßt sich mit den vier elektromagnetisch betätigten 2/2-Sitzventilen und einer entsprechenden Digitalsteuerung gut beherrschen.According to a further proposal of the invention, the device can be designed such that the shut-off devices located in the inlet and outlet of the hydraulic chamber are electromagnetically actuated 2/2 seat valves. In this way, the leakage on the valve side can be completely eliminated, which is absolutely necessary for precise dosing. In connection with a digital microprocessor control, the hydraulic flows can be controlled very easily individually. In particular, switching the metering or outflow line at different times can be mastered well with the four electromagnetically operated 2/2 seat valves and a corresponding digital control.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die 2/2-Sitzventile im stromlosen Zustand offen sind. Diese Ausführung bringt eine zusätzliche Sicherheit bei Stromausfall oder Kabelbruch, da sie in solchen Fällen alle Ventile durch Federkraft öffnet und ein Zerstören der Verdrängerelemente durch Überfahren der Endstellungen verhindert.According to a further proposal of the invention, the device can be designed such that the 2/2-seat valves are open in the de-energized state. This version provides additional security in the event of a power failure or cable break, since in such cases it opens all valves by spring force and prevents the displacement elements from being destroyed by passing the end positions.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß zusätzlich zu den 2/2-Sitzventilen ein 3/2-Proportional-Druckregelventil vorgesehen ist, das beim Umschalten der Dosierleitung und der Abströmleitung mittels der 2/2-Sitzventile über eine einstellbare Zeitdauer eine stetige Änderung des Volumenstroms und damit des Druckab- bzw. Aufbaus bewirkt. Mögliche Druckstöße in den Umschaltpunkten werden auf diese Art und Weise reduziert, da der Ölstrom nicht schlagartig beschleunigt bzw. verzögert wird. Druckstöße, die durch schnelles Umschalten der Dosier- und Abströmleitung verursacht werden, können durch diese Maßnahme nahezu beseitigt werden. Außerdem wird das 3/2-Proportional-Druckregelventil benutzt, um bei stark kompressiblen Dosiermedien eine zusätzliche Vorkompression zu erreichen, da in diesem Fall die Vorkompression durch den Druckausgleich der gemeinsam dosierenden Pumpen nicht mehr ausreicht. Im Idealfall wird der Vorkompressionsdruck bis auf das Druckniveau des Dosierdrucks angehoben, um eine theoretisch vollkommene Pulsationsfreiheit zu erreichen.According to a further proposal of the invention, the device can be designed in such a way that in addition to the 2/2 seat valves a 3/2-proportional pressure control valve is provided which, when the metering line and the outflow line are switched by means of the 2/2-way valves, causes a constant change in the volume flow and thus the pressure reduction or build-up over an adjustable period of time. Possible pressure surges in the switchover points are reduced in this way, since the oil flow is not suddenly accelerated or decelerated. Pressure surges caused by the rapid switching of the metering and discharge lines can almost be eliminated by this measure. In addition, the 3/2-proportional pressure control valve is used to achieve additional pre-compression in the case of highly compressible dosing media, since in this case the pre-compression is no longer sufficient due to the pressure equalization of the pumps dosing together. Ideally, the pre-compression pressure is raised to the pressure level of the dosing pressure in order to achieve a theoretically complete absence of pulsation.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die Druckmeßeinrichtung aus einem elektrischen Drucksensor besteht. Um das 3/2-Proportionaldruckregelventil der einen Verdrängerpumpe für die Vorkompression ansteuern zu können, bedarf es der Druckmessung durch einen Drucksensor der anderen Verdrängerpumpe. Mit dem gleichen Drucksensor werden auch die unterschiedlichen Dichtigkeitsprüfungen durchgeführt.According to a further proposal of the invention, the device can be designed such that the pressure measuring device consists of an electrical pressure sensor. In order to be able to control the 3/2 proportional pressure control valve of one positive displacement pump for the pre-compression, the pressure measurement by a pressure sensor of the other positive displacement pump is required. Different leak tests are carried out with the same pressure sensor.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß ein Personal Computer oder eine speicher-programmierbare Steuerung vorgesehen ist, der/die den Druckverlauf während der Dichtigkeitsprüfung auswertet. Der Druckverlauf in Abhähgigkeit von der Zeit muß festgehalten und mit abgespeicherten Werten verglichen werden. So ist eine Bewertung der Dichtigkeit der Verdrängerpumpen möglich. Für diese Aufgabenstellung bietet sich der Einsatz von SPS oder PC an, inbesondere weil fur die Steuerung der Verdrängerpumpen solche Geräte sowieso erforderlich sind.According to a further proposal of the invention, the device can be designed in such a way that a personal computer or a programmable logic controller is provided which evaluates the pressure curve during the leak test. The pressure curve as a function of time must be recorded and compared with stored values. This makes it possible to assess the tightness of the positive displacement pumps. The use of a PLC or PC is ideal for this task, especially because such devices are used to control the displacement pumps anyway required are.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß in jedem Hydraulikraum mindestens ein durch die Position des Verdrängerelements gesteuerter induktiver Näherungsschalter angeordnet ist. Um die Bewegung der oszillierenden Verdränger zueinander zu koordinieren, ist eine Lagekontrolle der Verdränger notwendig. Besonders einfach ist der Einsatz der induktiven Näherungsschalter, da sie im Gegensatz zu den Wegaufnehmern keine zusätzliche elektronische Auswerteeinheit benötigen, vielmehr genauso einfach zu handhaben sind wie mechanische Endschalter. Die Lagekontrolle der Verdränger erfolgt dabei durch jeweils einen druckfesten induktiven Näherungsschalter, der eine Nut auf einer an den Verdrängern befestigten Steuerstange überwacht.According to a further proposal of the invention, the device can be designed such that at least one inductive proximity switch controlled by the position of the displacement element is arranged in each hydraulic chamber. In order to coordinate the movement of the oscillating displacers to one another, a position control of the displacers is necessary. The use of inductive proximity switches is particularly easy, since, unlike the displacement sensors, they do not require an additional electronic evaluation unit, but are just as easy to use as mechanical limit switches. The position of the displacers is checked by a pressure-resistant inductive proximity switch, which monitors a groove on a control rod attached to the displacers.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die induktiven Näherungsschalter im unbetätigten Zustand durchgeschaltet sind. Der Ausfall eines induktiven Näherungsschalters (z.B, durch Kabelbruch) erfolgt in der Regel ohne Vorankündigung. Dies hätte das Fehlen eines Signals zur Folge, was unbedingt zur Umsteuerung der Verdrängerelemente benötigt wird. Fehlt dieses Signal, käme es zum Ausfall der gesamten Vorrichtung. Abhilfe kann durch den Einsatz eines induktiven Näherungsschalters geschaffen werden, der ständig ein Signal ausgibt. Der Umsteuerungsvorgang wird erst dann eingeleitet, wenn der Näherungsschalter kein Signal gibt. Fällt der Näherungsschalter durch einen Defekt aus, wird er stromlos und das jeweilige Verdrängerelement hydraulisch entlastet.According to a further proposal of the invention, the device can be designed such that the inductive proximity switches are switched through in the unactuated state. The failure of an inductive proximity switch (e.g. due to a cable break) usually takes place without notice. This would result in the absence of a signal, which is absolutely necessary for reversing the displacement elements. If this signal is missing, the entire device would fail. This can be remedied by using an inductive proximity switch that continuously outputs a signal. The reversal process is only initiated when the proximity switch does not give a signal. If the proximity switch fails due to a defect, it is de-energized and the respective displacement element is hydraulically relieved.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß in jedem Hydraulikraum mindestens ein durch die Position des Verdrängerelements gesteuerter induktiver Wegaufnehmer angeordnet ist. Der Vorteil des induktiven Wegaufnehmers liegt in seiner thermischen Belastbarkeit und in der Tatsache, daß er die Position der Verdrängerelemente kontinuierlich erfassen kann.According to a further proposal of the invention, the device can be designed such that at least one inductive displacement sensor controlled by the position of the displacement element is arranged in each hydraulic chamber. The advantage of the inductive displacement transducer lies in its thermal resilience and in the fact that it has the position which can continuously detect displacement elements.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die Position des Verdrangerelements durch volumetrische Wegmessung mittels der hydraulischen Dosiereinheit ermittelt wird. Grundsätzlich kann in den Verdrängerpumpen auf Lage-Sensoren verzichtet werden, wenn die dosierte Ölmenge als Maß für den zurückgelegten Weg des Verdrängerelements herangezogen wird. Nachteilig ist hierbei, daß nach Unterbrechungen und anderen Störungen die Position der Verdränger nicht ermittelt werden kann.According to a further proposal of the invention, the device can be designed such that the position of the displacement element is determined by volumetric displacement measurement by means of the hydraulic metering unit. In principle, position sensors can be dispensed with in the displacement pumps if the metered amount of oil is used as a measure of the distance traveled by the displacement element. The disadvantage here is that the position of the displacer cannot be determined after interruptions and other faults.

Gemäß einem weiteren Vorschlag der Erfindung kann die Vorrichtung so ausgebildet sein, daß die Steuerung der Verdrängerpumpeneinheit eine Mikroprozessorsteuerung ist (z.B. speicherprogrammierbare Steuerung oder Personal Computer). Der Steuerung der Vorrichtung nach der Erfindung kommt eine erhebliche Bedeutung zu. Sie kann grundsätzlich pneumatisch, hydraulisch oder elektrisch erfolgen. Bereits bei einer mit zwei induktiven Näherungsschaltern und vier Elektromagnet-Ventilen ausgerüsteten Verdrängerpumpeneinheit bietet sich eine kleine kompakte speicherprogrammierbare Steuerung (SPS) an. Die SPS bringt den Vorteil einer großen Flexibilität mit sich. Prozeßabläufe lassen sich damit optimal auf die gestellten individuellen Anforderungen abstimmen. Durch die zusätzliche Möglichkeit der Fehlererkennung und Diagnose können Fehlbedienungen rechtzeitig abgefangen und die Wartungszeit drastisch verkürzt werden. Aufgrund der sinkenden Preise für Personal Computer ist ein wirtschaftlicher Einsatz anstelle einer SPS schon bei weniger aufwendigen Prozessen sinnvoll, insbesondere dann. wenn die Prozeßabläufe visualisiert und dokumentiert werden sollen. Das Wartungspersonal wird dadurch in die Lage versetzt, alle maschinenrelevanten Daten am Bildschirm bzw. am Drucker zu verfolgen. Ferner ist eine Schnittstelle zu einem übergeordneten Leitrechner für die zentrale Meßdatenerfassung möglich.According to a further proposal of the invention, the device can be designed such that the control of the displacement pump unit is a microprocessor control (for example a programmable logic controller or personal computer). The control of the device according to the invention is of considerable importance. It can basically be done pneumatically, hydraulically or electrically. A small, compact programmable logic controller (PLC) is already available with a positive displacement pump unit equipped with two inductive proximity switches and four solenoid valves. The PLC has the advantage of great flexibility. Processes can be optimally matched to the individual requirements. The additional possibility of error detection and diagnosis means that incorrect operation can be intercepted in good time and the maintenance time can be drastically reduced. Due to the falling prices for personal computers, economical use instead of a PLC makes sense for less complex processes, especially then. if the process flows are to be visualized and documented. This enables maintenance personnel to track all machine-relevant data on the screen or on the printer. Furthermore, an interface to a higher-level master computer for central measurement data acquisition is possible.

Im folgenden Teil der Beschreibung werden das erfindungsgemäße Verfahren und eine zu seiner Durchführung geeignete Vorrichtung anhand einer Zeichnung beschrieben.In the following part of the description, the method according to the invention and a device suitable for carrying it out are described with reference to a drawing.

Die Ausführungsform gemäß der Zeichnung weist zwei baugleiche spiegelsymmetrische nicht selbstansaugende Verdrängerpumpen 1,2 auf, die sich in jeweils einem Gehäuse 3,4 befinden. Die beiden Verdrängerpumpen 1,2 bestehen aus jeweils einem Hydraulikraum 5,6 und jeweils einem Dosierraum 7,8, wobei jeweils zwischen einem Hydraulikraum 5,6 und einem Dosierraum 7,8 je eine kalottenförmige Formmembran 9,10 eingespannt ist, die jeweils auf ihrer dem Hydraulikraum 5,6 zugewandten Seite eine Steuerstange 11,12 trägt. Die Steuerstange 11,12 gibt ständig ein Signal an einen induktiven Näherungsschalter 13,14 aus. Überfährt eine der beiden Steuerstangen 11,12 den induktiven Näherungsschalter 13,14, so wird bei fehlendem Signal der Umsteuerungsvorgang eingeleitet, indem die induktiven Näherungsschalter 13,14 über eine elektrische Steuereinheit (o. Abb.) vier 2/2-Wegeventile 15,16,17,18 stromlos schalten. Die beiden 2/2-Wegeventile 15,16 verbinden die beiden Hydraulikräume 5,6 mit einer Dosierleitung 19, so daß beide Verdrängerpumpen 1,2 für eine von der elektrischen Steuerung (o. Abb.) festgelegte Zeit gleichzeitig fördern. Der Dosierhubbeginn der Verdrängerpumpe, die den Umsteuerungsvorgang eingeleitet hat, wird damit durch das ausbleibende Signal des induktiven Näherungsschalters 13 bzw. 14 festgelegt. Das Dosierhubende der Verdrängerpumpe, die den Umsteuerungsvorgang eingeleitet hat, wird dagegen von der elektrischen Steuereinheit (o. Abb.) mit einer Zeitverzögerung in Abhängigkeit von der Förderleistung der Verdrängerpumpen 1,2, bestimmt. Gleichzeitig mit dem Dosierhubende startet der Füllhubbeginn. Zwischen Füllhubende und dem Dosierhubbeginn pausiert die Verdrängerpumpe. d.h., sie ist weder mit der Abströmleitung 20 noch mit der Dosierleitung 19 verbunden. Jetzt können die Dichtigkeitsprüfungen nach dem erfindungsgemäßen verfahren durchgeführt werden, wozu die Drucksensoren 21,22 und das 3/2-Proportionaldruckregelventil 23 dienen. Beim Füllhubbeginn öffnen die federbelasteten Rückschlagventile 24,25 und schließen beim Füllhubende. Analog öffnen jeweils beim Dosierhubbeginn die Rückschlagventile 26,27 und schließen beim Dosierhubende. Die Druckbeaufschlagung der Verdrängerelemente 9,10 erfolgt durch eine hydraulische Dosiereinheit 28, die aus einem Hydraulikmotor 29 mit mechanisch gekoppeltem Servo- bzw. Schrittmotor 30 besteht, wobei der notwendige Vordruck für den Hydraulikmotor 29 aus einer Hydraulikdruckquelle 31 stammt, die auch das 3/2-Proportionaldruckregelventil 23 mit Hydraulikdruck versorgt.The embodiment according to the drawing has two identical mirror-symmetrical, not self-priming displacement pumps 1, 2, each of which is located in a housing 3, 4. The two positive displacement pumps 1, 2 each consist of a hydraulic chamber 5, 6 and a metering chamber 7, 8, a spherical dome-shaped membrane 9, 10, each of which is clamped on their, between a hydraulic chamber 5, 6 and a metering chamber 7, 8 the hydraulic chamber 5,6 facing side carries a control rod 11,12. The control rod 11, 12 continuously outputs a signal to an inductive proximity switch 13, 14. If one of the two control rods 11, 12 passes over the inductive proximity switch 13, 14, the changeover process is initiated in the absence of a signal by the inductive proximity switches 13, 14 using an electrical control unit (not shown) four 2/2-way valves 15, 16 , 17, 18 de-energize. The two 2/2-way valves 15, 16 connect the two hydraulic chambers 5, 6 with a metering line 19, so that both displacement pumps 1, 2 simultaneously deliver for a time determined by the electrical control (not shown). The start of the metering stroke of the displacement pump, which initiated the reversal process, is thus determined by the lack of a signal from the inductive proximity switch 13 or 14. The end of the metering stroke of the displacement pump that initiated the reversal process, on the other hand, is determined by the electrical control unit (not shown) with a time delay as a function of the delivery capacity of the displacement pumps 1, 2. The filling stroke begins at the same time as the end of the dosing stroke. The displacement pump pauses between the end of the filling stroke and the start of the dosing stroke. that is, it is neither connected to the discharge line 20 nor to the metering line 19. The leakage tests can now be carried out according to the method according to the invention, for what purpose the pressure sensors 21, 22 and the 3/2-proportional pressure control valve 23 are used. When the filling stroke begins, the spring-loaded check valves 24, 25 open and close at the end of the filling stroke. Similarly, the check valves 26, 27 open at the start of the metering stroke and close at the end of the metering stroke. The pressurization of the displacement elements 9, 10 takes place by means of a hydraulic metering unit 28, which consists of a hydraulic motor 29 with a mechanically coupled servo or stepping motor 30, the necessary pre-pressure for the hydraulic motor 29 coming from a hydraulic pressure source 31, which is also the 3/2 Proportional pressure control valve 23 supplied with hydraulic pressure.

Claims (19)

  1. Process for the controlled metering of at least one pourable component by means of a positive displacement pump unit for each component, whereby the said positive displacement pump unit is driven by a metered hydraulic current and comprises two positive displacement pumps (1, 2), each of which has an oscillating positive displacement element (9, 10), and whereby a metering pipe (19), which channels the metered hydraulic current, is connected to the hydraulic chamber (5) on one of the positive displacement pumps (1) via a current distributor unit, and to the hydraulic chamber (6) on the other positive displacement pump (2) via a flow-off pipe (20); on the basis of which, the metering pipe (19) is connected to the two hydraulic chambers (5, 6), whereby the metering pipe (19) is connected to the hydraulic chamber (6) on the second positive displacement pump (2), and the flow-off pipe (20) is connected to the hydraulic chamber (5) on the first positive displacement pump (1); the metering pipe (19) is then re-connected with the two hydraulic chambers (5, 6) and finally at the end of a cycle, and thus, at the start of the next cycle, the metering pipe (19) is connected once again to the hydraulic chamber (5) on the first positive displacement pump (1), and the flow-off pipe (20) is connected to the hydraulic chamber (6) on the other positive displacement pump (2), whereby the flow-off procedure in each positive displacement pump (1, 2) takes less time than metering and takes place during metering, characterised in that when either of the positive displacement pumps (1, 2) is inactive, whereby it is connected to neither the flow-off pipe (20) nor the metering pipe (19), possible changes in hydraulic pressure in the relevant hydraulic chamber (5, 6) are measured within a defined time interval.
  2. Process in accordance with claim 1, characterised in that during periods of time when either one of the positive displacement pumps (1, 2) is inactive, whereby it is connected to neither the flow-off pipe (20) nor the metering pipe (19), the metering and hydraulic medium is pre-compressed by virtue of the fact that the hydraulic pressure in the hydraulic chamber (5, 6) in question is increased by a hydraulic pressure source (31) up to metering pressure at most, and in that possible changes in hydraulic pressure in the hydraulic chamber (5, 6) in question are then measured within a defined time interval.
  3. Process in accordance with claims 1 or 2, characterised in that during periods of time when both of the positive displacement pumps (1, 2) are inactive, the metering and hydraulic medium is pre-compressed by virtue of the fact that the hydraulic pressure in all of the hydraulic chambers (5, 6) is increased by a hydraulic pressure source (31), and in that possible changes in hydraulic pressure are then measured within a defined time interval.
  4. A device which is suitable for performing the process in accordance with one of the foregoing claims, used for the controlled metering of at least one pourable component, whereby each component has two oscillating positive displacement pumps (1, 2), which are either self-priming or which operate with a pre-compressed supply mechanism, whereby each of the pumps is designed with a positive displacement element (9, 10), and whereby in each component a hydraulic metering unit (28) is connected to the two hydraulic chambers (5, 6) of the two positive displacement pumps (1, 2) via a shut-off device (15, 16), which is sealed against leakages; at least one hydraulic metering unit (28) is supplied via a hydraulic pressure source (31); a shut-off device (15, 16, 17, 18; 24, 25, 26, 27) is arranged at the inlet and outlet of the metering chamber (7, 8) and of the hydraulic chamber (5, 6) on each of the positive displacement pumps (1, 2), a pressure measuring device (21, 22) is connected to the hydraulic chamber (5, 6) on each of the positive displacement pumps (1, 2), and the positive displacement pumps (1, 2) are designed with a control system which coordinates the timing of the suction strokes, and the filling and metering strokes.
  5. Device in accordance with claim 4, characterised in that the positive displacement elements (9, 10) are diaphragms.
  6. Device in accordance with claim 5, characterised in that the diaphragms comprise at least two separate membranes positioned on top of one another and forming a circulatory point of rigid support, whereby there is a space between the individual membranes and where each space is fitted with a leakage drain via a point of rigid support.
  7. Device in accordance with claim 4, characterised in that the positive displacement elements (9, 10) are bellows.
  8. Device in accordance with claim 7, characterised in that the bellows comprise two dividing walls positioned on top of one another, whereby there is a space between the dividing walls and where each space is fitted with a leakage drain via a point of rigid support.
  9. Device in accordance with one of claims 4 to 8, characterised in that the shut-off devices (24, 25, 26, 27) located at the inlet and outlet of the metering chamber (7, 8) are automatic back-pressure valves.
  10. Device in accordance with one of claims 4 to 9, characterised in that the shut-off devices (15, 16, 17, 18) located at the inlet and outlet of the hydraulic chamber (5, 6) are electromagnetically operated 2/2 seat valves.
  11. Device in accordance with claim 10, characterised in that the 2/2 seat valves (15, 16, 17, 18) are open when no current is flowing through.
  12. Device in accordance with claim 10, characterised in that, in addition to the 2/2 seat valves (15, 16, 17, 18), there is also a 3/2 proportional pressure control valve (23) which can continuously alter the volumetric flow, and thus the reduction and build-up of pressure, over a predefined period of time, when switching between the metering pipe (19) and the flow-off pipe (20) by means of the 2/2 seat valves (15, 16, 17, 18).
  13. Device in accordance with one of claims 4 to 12, characterised in that the pressure measuring device (21, 22) comprises an electrical pressure sensor.
  14. Device in accordance with one of claims 4 to 13, characterised in that a personal computer or a programmable controller is attached, which analyses the pressure pattern during the consistency test.
  15. Device in accordance with one of claims 4 to 14, characterised in that there is at least one inductive proximity switch (13, 14), which is controlled by the position of the positive displacement element (9, 10), in each hydraulic chamber (5, 6).
  16. Device in accordance with claim 15, characterised in that the inductive proximity switches (13, 14) are enabled when not actuated.
  17. Device in accordance with one of claims 4 to 14, characterised in that there is at least one inductive displacement sensor (9, 10), which is controlled by the position of the positive displacement element (9, 10), in each hydraulic chamber (5, 6).
  18. Device in accordance with one of claims 4 to 14, characterised in that the position of the positive displacement element (9, 10) is determined by performing a volumetric displacement measurement using the hydraulic metering unit (28).
  19. Device in accordance with one of claims 4 to 18, characterised in that the control system for the positive displacement pump unit is a microprocessor control system (such as a programmable controller or a personal computer).
EP92909623A 1991-05-03 1992-05-04 Process and device for the controlled metering of at least one pourable component Expired - Lifetime EP0582625B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4114438 1991-05-03
DE4114438 1991-05-03
PCT/DE1992/000352 WO1992019867A1 (en) 1991-05-03 1992-05-04 Process and device for the controlled metering of at least one pourable component

Publications (3)

Publication Number Publication Date
EP0582625A1 EP0582625A1 (en) 1994-02-16
EP0582625B1 true EP0582625B1 (en) 1996-01-24
EP0582625B2 EP0582625B2 (en) 2005-01-05

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EP92909623A Expired - Lifetime EP0582625B2 (en) 1991-05-03 1992-05-04 Process and device for the controlled metering of at least one pourable component

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EP (1) EP0582625B2 (en)
JP (1) JPH06506999A (en)
AT (1) ATE133471T1 (en)
DE (1) DE59205185D1 (en)
WO (1) WO1992019867A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0781922B1 (en) * 1995-12-28 2000-11-29 Van Wijk Engineering B.V. Double-acting membrane pump
JP6362008B2 (en) * 2015-02-09 2018-07-25 Smc株式会社 Pump system and pump abnormality detection method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3072462A (en) * 1959-09-17 1963-01-08 Controls Co Of America Mixing apparatus
DE2741024A1 (en) * 1977-09-12 1979-03-22 Wilms Gmbh DIAPHRAGM PUMP
US4778356A (en) * 1985-06-11 1988-10-18 Hicks Cecil T Diaphragm pump
JPS62131987A (en) * 1985-12-05 1987-06-15 Takeshi Hoya Doubly connected pressure feeding device
FR2605059B1 (en) * 1986-10-08 1991-02-08 Schlumberger Cie Dowell FLOW MEASUREMENT AND MONITORING SYSTEM FOR POSITIVE DISPLACEMENT PUMPS AND PUMPS PROVIDED WITH SUCH SYSTEMS

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EP0582625B2 (en) 2005-01-05
DE59205185D1 (en) 1996-03-07
EP0582625A1 (en) 1994-02-16
WO1992019867A1 (en) 1992-11-12
ATE133471T1 (en) 1996-02-15
JPH06506999A (en) 1994-08-04

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