DE102015108964B4 - Method for controlling a diaphragm pump, in particular a double diaphragm pump - Google Patents

Abstract

Method for controlling a diaphragm pump (1), in particular a double diaphragm pump, in which
• A sensor (6) measures a measurement signal (M), in particular continuously or clocked; which detects a displacement path (90) of a membrane (2 ₁ , 2 ₂ ) which separates a delivery chamber (4 ₁ , 4 ₂ ) from a drive space (3 ₁ , 3 ₂ ); and at the
A control unit (7) of the membrane pump (1)
◯ detects an operating status of the diaphragm pump (1) on the basis of the measuring signal (M),
◯ sets or calculates a reversal point (U) as a function of the detected operating status of the diaphragm pump (1), and
◯ a changeover valve (8) controls that this the diaphragm pump (1) of a first operating mode (I) in which the drive space (3 ₁ , 3 ₂ ) is printed with a medium in a second operating mode (II), in the drive space (3 ₁ , 3 ₂ ) is de-pressurized, or switches back when the detected displacement path (90) is equal to or greater than the reversal point (U), characterized in that the control unit (7) the reversal point (U) in dependence controls at least two operating status, wherein the reversal point (U) is provided in a steady state operation status with a smaller stroke than in a start-up operation status.

Description

State of the art

The present invention relates to a method for controlling a diaphragm pump according to the preamble of claim 1.

In addition, the invention relates to a diaphragm pump according to the preamble of claim 13.

A method for regulating a diaphragm pump describes the DE 693 02 765 T2 which discloses a pump control interface in a diaphragm pump, the pump interface, and a fluid driven diaphragm pump, wherein information about the position and travel speed of a pump diaphragm is provided by means of an electronic sensor device. In this case, the position and velocity of a membrane during a suction and a discharge stroke are detected by a sensor which is surrounded by the pump control interface arranged in the diaphragm pump, by means of display means detectable on a membrane follower rod and the sensor designed as a proximity switch.

Diaphragm pumps are used to convey fluids. Fluids in the sense of this invention are gases, liquids or particulate solids whose flow behavior is similar to that of liquids (particle flow). The diaphragm pumps allow leakage-free delivery of such fluids by a drive space of the diaphragm pump is separated by a membrane hermetically from a pumping chamber, which is provided for conveying the fluid. To drive the diaphragm pump, the membrane is acted upon by a drive medium, which is introduced into the drive space.

To promote abrasive, aggressive and explosive fluids preferably pneumatically operated diaphragm pumps are used, which are operated with an inert gas or compressed air. Since they are not driven electrically, they are also used in potentially explosive environments. In addition, for larger flow rates or pulsationsarmer promotion mostly pneumatic double diaphragm pumps are in use, which instead of a single membrane two alternately actuated membranes for conveying the fluid, and therefore are more efficient operable. Both membranes each separate a drive space from a delivery space, so that the double diaphragm pump has two drive spaces and two delivery spaces.

A double membrane pump according to the prior art is in 1 described.

Opposite electrically driven pumps have pneumatically or hydraulically operated diaphragm pumps the advantage that they allow high pressures while sparing the membrane, since the load on the diaphragm rear side is not done mechanically by plunger or pressure plates, but with the help of the drive medium by a uniform pressure build-up in the drive compartment. The drive medium acts essentially over the entire area on the entire membrane back. As a result, the membrane is loaded significantly less than with a mechanical load by ram or pressure plates and has a much longer service life.

Another significant factor influencing the lifetime of a membrane is the membrane's stroke during operation. The longer the stroke of the membrane, the more the membrane is deformed and stressed. This considerably reduces their service life.

For the production of membranes preferably elastic materials are used. Such materials are, for example, elastomers or thermoplastic elastomers. For contact with aggressive fluids, composite membranes are preferably used. Composite membranes are usually made of an elastic base material, which is laminated to the fluid side or on the side facing the pumping chamber with a chemically resistant film, such as PTFE. They are chemically resistant, but have a relatively low mechanical strength. However, the flexing / deformation of the membrane during operation leads to high local stresses in the PTFE layer and the lamination. The result is premature damage such as film removal, fiber breaks or whitening of the PTFE layer. Gentle loading of the membranes with low deformations is thus desirable in order to increase the service life of the membrane.

Another disadvantage of membrane pumps is that the flow rate of the fluid is dependent on the operating pressures that occur at the inlet and outlet of the diaphragm pump and on the pressure supply. If only one operating parameter is changed, the delivery rate also changes. A constant flow rate is therefore very difficult or impossible to achieve with pneumatically or hydraulically operated diaphragm pumps with fluctuating operating parameters.

Furthermore, the start-up of a diaphragm pump, for example, after an interruption of the promotion due to a power failure, not possible when the valve position of a valve with which used for printing the membrane Medium in the drive space can be introduced, is arranged in an intermediate position. Conventionally, costly countermeasures, such as the installation of bistable changeover valves, are provided for this case.

In addition, the medium used for printing the membrane in case of a defect of the membrane, for example, in a membrane fracture, from the pressure-loaded drive chamber enter the pumping chamber. The fluid to be delivered is then permeated with the medium. In many applications this influence is not only undesirable but harmful. Conversely, if the membrane is defective or if higher pressures prevail in the delivery chamber than in the drive space, it is also possible for fluid to penetrate into the drive space. The resulting impurities cause expensive cleaning work on the diaphragm pump.

epiphany

The object of the present invention is therefore to eliminate the above-described disadvantages of diaphragm pumps, and to provide a method for controlling a diaphragm pump, in particular a pneumatically operated double diaphragm pump, which promotes the promotion of a substantially constant flow rate of the fluid, a very accurate adjustability of the Flow rate of the fluid, adjustability of (maximum) frequency and / or a (maximum) reversal point (stroke) of the membrane, an output of maintenance information, in particular a residual life or a defect of the membrane, and / or a start-up of the diaphragm pump after a stoppage allows , which is inexpensive to operate, and with a membrane fracture is avoidable as possible. Another object of the present invention is to provide a diaphragm pump for carrying out the method.

The object is achieved with a method having the features of independent claim 1, and a diaphragm pump with the features of independent claim 13. Advantageous embodiments are the dependent claims.

The method for controlling a diaphragm pump, in particular a double diaphragm pump, which achieves the object, provides to detect the displacement of the membrane of the diaphragm pump, and to compare with a reversal point.

The method for regulating the diaphragm pump is characterized in that a sensor measures the measurement signal, in particular continuously or clocked, and a control unit first determines an operating status of the diaphragm pump based on the measurement signal and then adjusts or calculates the reversal point as a function of the operating status of the diaphragm pump , It is also provided that the control unit controls the reversal point by controlling a valve position of the changeover valve.

In this case, it is provided that the control unit controls the reversal point as a function of at least two operating states, the reversal point being provided in a continuous operating status with a smaller stroke than in an operating status of starting operation.

The method allows the reversal point to be automatically adjusted or calculated depending on the operating status. In this case, the control unit recognizes the operating state of the diaphragm pump at the measuring signal, for example at a changing frequency of the measuring signal.

The control unit preferably controls the reversal point as a function of at least two operating states. Also preferably, the control unit controls the reversal point in dependence on three operating states.

When the diaphragm pump starts up, it is in the start-up operating status. In this operating status, a delivery chamber, which is provided for conveying a fluid, and into which the fluid can be introduced and redirected, is initially still free of the fluid to be delivered. Instead, there is air in the delivery room, for example. However, with continuous operation of the diaphragm pump more and more of the fluid to be delivered is conveyed into the pumping chamber. As a result, the compressibility of the fluid located in the delivery chamber and the resistance with which this counteracts the membrane change.

In the operating status continuous operation, however, the delivery chamber is substantially filled with the fluid to be delivered.

In addition, in the event of a fault, for example a diaphragm rupture, it is possible for the medium used to drive the diaphragm to enter the delivery chamber. It is preferred that the control unit detects such an error case with an operating status error operation.

In the case of air initially located in the delivery chamber, for example, the resistance with which the air of the membrane counteracts is low due to its compressibility. If a fluid or a particle flow is conveyed as fluid, the resistance to that of the air is considerably greater. The changing resistance leads to a change in the frequency of the measuring signal. In addition, changes the signal curve of the measuring signal via the membrane path.

In a preferred embodiment, the operating status is determined by the control unit calculating a switching frequency of the diaphragm pump from the measurement signal, in particular from at least two successively detected values of the measurement signal, and determining the operating status based on the switching frequency. The switching frequency of the diaphragm pump is a measure of the time that elapses between switching the diaphragm pump from the first to the second operating mode and back again. In startup mode, the switching frequency changes, since the proportion of the fluid to be pumped in the drive chamber increases. In continuous operation, it is essentially constant, since the drive space is substantially filled with the fluid to be delivered. An error operation, for example, due to a diaphragm rupture, leads to a changing switching frequency, since the drive medium gets into the drive space.

The control unit therefore preferably detects the operating status as a function of the current operating status when the switching frequency either decreases or increases, depending on whether a change of the fluid in the delivery chamber from a more compressible fluid to a less compressible fluid or vice versa, and / or when a changing switching frequency reaches a constant value or when a constant switching frequency changes.

Alternatively or additionally, it is preferred that the operating status is determined by the control unit determining the operating status by a comparison process of the measuring signal with reference signals. Also in this method, the behavior of the membrane is used due to the different compressibilities of the fluid located in the delivery chamber. With a compressible fluid, the resistance with which it counteracts the membrane increases with increasing deformation of the membrane. For a non-compressible fluid, however, it is essentially constant. The operating status can therefore be determined from the shape of the measuring signal.

Alternatively or additionally, it is preferred that the operating status is determined by the control unit calculating a speed and / or an acceleration of the diaphragm from the measurement signal, and acquiring the operating status by a comparison process of the speed waveform and / or the acceleration waveform with reference signals , Again, the behavior of the membrane is used due to the different compressibility of the fluid located in the pump room.

The determination of the operating status by evaluation of the measuring signal has the advantage that no manual switching of the diaphragm pump from starting operation to continuous operation by an operator is required. Furthermore, the method enables an operational calculation of the reversal point. In addition, it makes it possible to detect a fault, in particular a diaphragm rupture.

In a particularly preferred embodiment, the control unit controls a switching valve, which is provided for switching the diaphragm pump from the first to the second operating mode or back, or a shut-off valve upstream of the switching valve in continuous operation so that a supply of the medium in the drive space between the switching in each case for a short time is interrupted. As a result, it is possible on the one hand that a preset or calculated, in particular maximum, switching frequency is not exceeded. Since the membrane is very heavily loaded at a very rapid deformation, the method of this embodiment allows extending their life by limiting the switching frequency. It is particularly preferred that the switching frequency is adjustable at a user interface.

In addition, it is thereby possible to operate the diaphragm pump, in particular in continuous operation, with a substantially constant switching frequency. The method thus enables a presetting of the delivery of the fluid to be conveyed by the operator, and a very accurate compliance with the set flow rate. For this purpose, the control unit preferably calculates the number of strokes still required for conveying the set delivery rate from the reversal point of the membrane. Furthermore, it preferably calculates from this the remaining time required. It is particularly preferred for the control unit to output or display the still required number of strokes and / or the remaining time at the user interface.

Also preferably, the still required number of strokes and / or the remaining time are adjustable on the user interface. Particularly preferably, the control unit controls the switching valve or a shut-off valve upstream of the switching valve so that the supply of the medium is terminated when the set or calculated number strokes of the membrane, or the set flow rate of the fluid to be delivered with the diaphragm pump is reached. The control unit then preferably switches off the diaphragm pump.

In a further preferred embodiment, the control unit controls a Switching valve upstream throttle for changing a volume flow of the medium, in particular an electrically controllable proportional valve, so that the volume flow in the start-up operation is greater than in continuous operation. This also allows actuation of the membrane at substantially constant speed. In addition, the throttle allows the diaphragm to be operated at a lower speed in the startup operating status than in the continuous operation status. As a result, a higher intake volume can be reached in the starting operation.

Particularly preferably, the control unit controls the throttle so that the volume flow of the medium is constant in continuous operation. For this purpose, it is particularly preferred that the control unit controls the throttle as a function of a pressure signal measured with a pressure sensor such that a pressure of the medium on the diaphragm is constant. For this purpose, the diaphragm pump preferably has a first pressure sensor, which is arranged between the changeover valve and the throttle. The pressure sensor preferably forms a control loop with the throttle. As a result, the operating pressure of the medium acting on the membrane is still substantially constant even with changing / fluctuating medium supply.

In a further preferred embodiment, the control unit shuts off the supply of the medium when the pressure drops below a limiting pressure. For this purpose, the diaphragm pump preferably has a second pressure sensor for measuring the operating pressure of the medium upstream of the throttle. The detection of the operating pressure allows control of the air distribution in a supply network and a prioritization of several consumers connected to the supply network. If the diaphragm pump has a subordinate function, it is preferred that the control unit interrupts or shuts off the diaphragm pump when the operating pressure falls below a limit value. The medium is then available to other consumers.

In a further preferred embodiment, the control unit controls a transverse venting valve so that it briefly connects a first supply line with a second supply line between the switching from the first to the second operating mode or back. The diaphragm pump for carrying out this method is a double diaphragm pump with two alternately actuated membranes. For this purpose, it preferably has the transverse venting valve, or a reversing valve in which the transverse venting valve is integrated. The transverse venting valve is arranged between a first supply line of the medium to the first drive space of the first diaphragm and a second supply line of the medium to the second drive space of the second diaphragm. It is intended for connecting the supply lines. The control unit preferably controls the transverse venting valve as a function of the operating state, the deflection and / or the speed of the membrane. With the cross-ventilation valve, a pressure equalization between the supply lines is possible. As a result, the consumption of the medium of the double diaphragm pump can be significantly reduced.

Preferably, the control unit detects an asymmetry of the measurement signal and / or the signal course of the speed and / or the acceleration by a comparison process with reference signals, in particular as maintenance information. It is preferable that the maintenance information is output to the user interface.

In the embodiment as a double diaphragm pump, it is further preferred that the control unit detects an asymmetry of the measurement signal and / or the signal profile of the speed and / or the acceleration by a comparison process of the signal component in the first operating mode with the signal component in the second operating mode and / or reference signals. The comparison process allows conclusions to be drawn about the condition of one or the membranes. An asymmetrical course indicates damage to one of the membranes or even an imminent membrane rupture. Upon detection of an imbalance, it is preferred that the control unit issue a warning or stop the diaphragm pump to prevent diaphragm rupture.

• • Der Verschiebeweg der Membran,
• • Der Umkehrpunkt der Membran,
• • Der Betriebsstatus der Membranpumpe,
• • Die aktuell geförderte Menge Fluid,
• • Die Fördermenge des Fluides,
• • Die geförderte Menge Medium,
• • Der durchschnittliche Druck des Mediums auf die Membran,
• • Der Betriebsdruck des Medium/der Mediumszufuhr,
• • Die aktuelle, noch erforderliche Anzahl und/oder Gesamtzahl Hübe der Membran,
• • Die durchschnittliche noch verbleibende Lebensdauer der Membran,
• • Die Warnung, dass die Membran sich unsymmetrisch deformiert.

The control unit particularly preferably stores maintenance information and / or operating data, in particular as a function of time, continuously, and / or outputs them at the user interface. Such maintenance information and / or operating data are, for example

• • the displacement of the membrane,
• • the reversal point of the membrane,
• • the operating status of the diaphragm pump,
• • The currently funded amount of fluid,
• • The flow rate of the fluid,
• • The pumped amount of medium,
• • the average pressure of the medium on the membrane,
• • the operating pressure of the medium / medium supply,
• • The current, still required number and / or total strokes of the membrane,
• • The average remaining life of the membrane,
• • The warning that the diaphragm deforms asymmetrically.

For this purpose, it is preferred that the control unit comprises a data memory, in particular a read-only memory. In addition, it is preferred that the control unit comprises a programmable central processing unit (CPU). The central processing unit is preferably provided for recording the maintenance information and / or operating data and their evaluation. The central processing unit used is preferably a microcontroller or a microprocessor.

Furthermore, it is preferred that the control unit has a user interface. The user interface is provided for outputting the maintenance information and / or operating data. For this, it is preferred that it comprises a display means or an interface for connecting the display means. In a preferred embodiment, the display means is a display, in particular a liquid crystal screen, for example an LCD (liquid crystal display), in particular a TFT (thin film transistor) screen.

In addition, it is preferred that the user interface is provided for presetting the operationally relevant variable or several operationally relevant variables. In this embodiment, it is designed, for example, for manual data entry, for example via an integrated or connectable to the diaphragm pump keyboard.

Alternatively or additionally, it is preferred that the user interface comprises a data interface, for example a radio interface, an infrared interface, a Bluetooth interface, a serial interface, a USB interface, an Ethernet interface, a WLAN (wireless local area network ) Interface, NFC (near field communication) interface or similar. At this interface, the maintenance information and / or operating data from or to an external input and output device, such as a cell phone or a computer, transferable.

In a particularly preferred embodiment, the display means is designed as a touch screen, so that a presetting of reference data directly on the display is possible. This eliminates the otherwise required for manual input keyboard.

The object is further achieved with a membrane pump, in particular double diaphragm pump, which is designed to carry out the method according to the invention.

The membrane pump has for this purpose at least one membrane. The membrane separates a drive space, which is provided for its drive, from a delivery space, which is provided for conveying a fluid, from each other, preferably hermetically. But it is fully enclosed on its periphery.

It can be driven by applying a medium in the drive compartment. In a first operating mode of the diaphragm pump, the membrane can be printed by applying the medium into the drive space. It is deformed, starting from an undeformed ground state, in a direction of displacement. In the deformation state deformed in the direction of displacement, it is deformed into the delivery chamber.

In a second operating mode of the diaphragm pump, it can be pressurized by removing the medium from the drive chamber. It is, starting from the deformed in the direction of deformation deformation state, formed back into the undeformed ground state, and deformed from there against the displacement direction in a deformed deformation state. In the deformation state deformed against the displacement direction, it is deformed into the drive space. From the deformation state deformed into the drive space, it can be reformed back into the undeformed ground state in the displacement direction.

It is preferred that the membrane in the undeformed ground state is deformed into neither the drive chamber nor the delivery chamber. In the following, the deformation state in which the membrane is deformed in the direction of displacement into the delivery chamber is referred to as the first state of deformation. The deformation state in which the membrane is deformed against the direction of displacement into the drive space is referred to below as the second state of deformation.

A change between the printing and the printing of the drive space, d. H. a switching between the operating modes of the diaphragm pump, therefore causes a change of direction between the displacement in the direction of displacement and the displacement against the displacement direction. The direction change takes place at a reversal point.

The drive medium used for printing on the membrane, hereinafter also referred to as the medium, is preferably a gas, in particular air or an inert gas. Likewise preferred it is a liquid, in particular an oil.

The funded with the membrane pump fluids are preferably liquids, with particles permeated liquids, or particles whose flow behavior resembles those of liquids (particle flow), in particular oils, paints and varnishes. Gases are also preferred as fluids.

When printing or de-printing the membrane, the membrane is reversibly deformed from the ground state by a displacement in the first or second deformation state. It is deformed by a displacement.

The diaphragm pump is characterized in that it comprises a sensor which is provided for detecting the displacement path.

The displacement is a measure of the deformation / deflection of the diaphragm, both for the amount by which the diaphragm is deformed / deflected and for the displacement direction in which the diaphragm is deformed / deflected. In order to detect the displacement path of the membrane, the diaphragm pump has a sensor for measuring a measuring signal. Preferably, the sensor detects the amount of the displacement and the direction of displacement. The knowledge of the displacement allows a targeted influence on the deformation of the membrane. As a result, it allows a conclusion and an influence on the flow of the fluid, that is, on the amount of fluid delivered in a unit time, as well as the funded total amount of the fluid.

The sensor provided for detecting the displacement path preferably detects it magnetically, electromagnetically or inductively. This not only enables a discrete detection of the displacement as a function of time, but the displacement is characterized by continuous / analog during the entire deformation of the membrane detectable both in and against the direction of displacement. As a result, not only the displacement is known, but the detection also allows a conclusion on the speed and acceleration of the membrane. The speed and acceleration of the membrane can therefore be monitored. On the basis of the speed and / or acceleration curve of the membrane, an evaluation of the pumped fluid and the membrane state is possible.

The invention is not limited to magnetic, electromagnetic or inductive sensors, but includes other sensors such as sound sensors, in particular ultrasonic sensors, light sensors, capacitive sensors or potentiometric sensors for detecting the displacement.

Particularly preferably, the sensor is designed as a non-contact sensor. The components used to capture the displacement of the sensor therefore do not touch. In this embodiment, the detection of the displacement path is permanently lossless possible.

With the or the sensors of the displacement of the membrane is detected. As a result, the diaphragm pump can be controlled or regulated in a displacement-dependent manner.

In order to control the diaphragm pump as a function of the detected displacement, it has at least one operating means. The diaphragm pump is preferably designed to control at least one technical setting of the operating means as a function of the detected displacement path.

The operating means is preferably an electrical switching valve, which is provided for switching the diaphragm pump in a reversal point of the diaphragm from the first operating mode in which the drive space is printed with a medium in the second operating mode in which the drive space is unprinted or back. It is therefore used to switch between the printing and the Entdrucken the membrane. It is preferred that the technical adjustment of the changeover valve is a valve position of the changeover valve. Preferably, the switching valve has at least two valve positions, between which it is switchable.

In a first preferred embodiment, the switching valve is a 5/2-way valve. In this embodiment, it allows in a first valve position, the printing of the membrane with the medium. In a second valve position, it allows the Entdrucken the membrane, in which the medium is removed from the drive space.

In a double diaphragm pump, ie a diaphragm pump with two alternatingly printed membranes, in a second preferred embodiment, the changeover valve is a 5/3-way valve. The 5 / 3 - Directional valve allows in addition to the printing of one of the two drive spaces of the membranes and the Entdrucken this drive space also has a third valve position in which the air supply is interrupted. A diaphragm pump with such a switching valve can be stopped in any position, especially when the predetermined flow rate is reached.

Alternatively or additionally, it is preferred that the diaphragm pump has a shut-off valve, which is connected upstream of the changeover valve, in particular the 5/2-way valve. In this embodiment, with the shut-off valve, the supply of the medium, and therefore also the delivery of the fluid, are interrupted.

The switching valve designed as a 5/3-way valve or the shut-off valve are also controllable so that a supply of the medium in the drive space between the switching from the first to the second operating mode or back briefly is interrupted, especially if a preset or calculated switching frequency is exceeded. This makes it possible that a preset or calculated, in particular maximum, switching frequency is not exceeded. Since the membrane is very heavily loaded at a very rapid deformation, the method of this embodiment allows extending their life by limiting the switching frequency.

The diaphragm pump also has a control unit for controlling the switching valve. The control unit is configured to control the changeover valve to switch the diaphragm pump from the first operating mode to the second operating mode or back when the detected displacement is equal to or greater than the reversing point. It is preferred that the control unit adjusts the reversal point operating status automatically.

In a particularly preferred embodiment, the membrane pump is a double-membrane pump. In this embodiment, it has a first membrane, which separates a first drive space from a first delivery space, and a second membrane, which separates a second drive space from a second delivery space. The diaphragm pump has a guide means for connecting the two membranes together. The membranes are synchronized with the guide means so that they are mutually operable.

In the first operating mode of the double diaphragm pump, the first membrane is printed with the medium, so that it deforms by the displacement in the direction of displacement. At the same time, the second membrane is de-pressurized in the direction of displacement. In the second operating mode, the second membrane is printed with the medium, so that it deforms by the displacement against the displacement direction. At the same time, the first diaphragm is de-pressurized against the displacement direction.

In the first deformation state, therefore, the first membrane is deformed in the direction of displacement into the first delivery chamber. In the second deformation state, it is deformed against the displacement direction into the first drive space. The second diaphragm is deformed in the first deformation state in the direction of displacement in the second drive space, while it is deformed in the second deformation state against the displacement direction into the second pumping chamber.

It is particularly preferred that the medium is air. The diaphragm pump of this embodiment therefore has a pneumatic drive.

It is preferred that the diaphragm pump has, in addition to the switching valve, further operating means for controlling the diaphragm pump. Particularly preferably, it has a throttle, in particular an electrically controllable proportional valve, which is connected upstream of the changeover valve. The throttle is provided for varying a volume flow of the medium. The control unit preferably controls the throttle in such a way that the volume flow in the starting operation is greater than in continuous operation. As a result, a higher intake volume can be reached in the starting operation. In addition, the throttle allows actuation of the membrane at a substantially constant speed.

Furthermore, it is preferred that the diaphragm pump as a further operating means comprises a first pressure sensor, which is arranged between the switching valve and the throttle. In this embodiment, the control unit is provided to control the throttle in dependence on the pressure signal measured by the pressure sensor so that a pressure of the medium is constant on the membrane. The pressure sensor preferably forms a control loop with the throttle. As a result, the operating pressure of the medium acting on the membrane is still substantially constant even with changing / fluctuating medium supply.

Also preferably, the diaphragm pump to a second pressure sensor for measuring an operating pressure of the medium, which is connected upstream of the throttle. In this case, the control unit is provided to switch off the supply of the medium when falling below a threshold pressure. The detection of the operating pressure allows control of the air distribution in a supply network and a prioritization of several consumers connected to the supply network.

In the case of a diaphragm pump designed as a double diaphragm pump, it is also preferred that it has a transverse venting valve as a further operating means, which is arranged between a first feed line of the medium to the first drive space of the first membrane and a second feed line of the medium to the second drive space of the second membrane. Alternatively, it is preferred that such a transverse ventilation valve is integrated in the changeover valve. The control unit preferably controls the transverse venting valve in such a way that it briefly connects the first supply line to the second supply line between the switchover from the first to the second operating mode or back. It is preferred that the control unit, the transverse vent valve depending on the operating condition, the Deflection and / or speed of the membrane controls. With the cross-ventilation valve, a pressure equalization between the supply lines is possible. As a result, the consumption of the medium of the double diaphragm pump can be significantly reduced.

The method allows automatic adjustment of the reversal point depending on the operating status of the diaphragm pump. As a result, a very accurate adjustment of the flow rate and the volume flow of the fluid is possible. In this case, the diaphragm pump is controlled so that the membrane, especially in continuous operation, is only slightly loaded. As a result, it has a significantly increased lifespan. By evaluating the detected displacement path, it is also possible to draw conclusions about the condition of the diaphragm. The diaphragm pump is then controlled to prevent diaphragm rupture.

• 1 zeigt eine Doppelmembranpumpe nach dem Stand der Technik;
• 2 - 5 zeigen jeweils eine Ausführungsform einer erfindungsgemäßen Doppelmembranpumpe mit einem Sensor zum Erfassen des Verschiebeweges der Membranen;
• 6 zeigt schematisch eine erfindungsgemäße Doppelmembranpumpe mit einer an die Doppelmembranpumpe angeschlossenen Elektronik;
• 7 zeigt in (a) und (b) schematisch jeweils den Verlauf des Messsignals, und in (c) und (d) schematisch jeweils den Verlauf der Geschwindigkeit der Membranen, und zwar in (a) und (c) jeweils bei einem im Förderraum befindlichen, nicht oder nahezu nicht komprimierbaren Fluid, und in (b) und (d) jeweils bei einem im Förderraum befindlichen komprimierbaren Fluid; und
• 8 - 11 zeigt verschiedene Ausführungsformen weiterer erfindungsgemäßer Doppelmembranpumpe in unterschiedlichen Ausbaustufen.

In the following the invention will be described with reference to figures. The figures are merely exemplary and do not limit the inventive idea.

• 1 shows a double membrane pump according to the prior art;
• 2 - 5 each show an embodiment of a double diaphragm pump according to the invention with a sensor for detecting the displacement path of the membranes;
• 6 schematically shows a double diaphragm pump according to the invention with an electronics connected to the double diaphragm pump;
• 7 shows in (a) and (b) schematically each the course of the measurement signal, and in (c) and (d) each schematically the course of the velocity of the membranes, in (a) and (c) respectively at a located in the pump room , not or nearly incompressible fluid, and in (b) and (d), respectively, in a compressible fluid located in the delivery chamber; and
• 8th - 11 shows various embodiments of further inventive double diaphragm pump in different stages of development.

1 shows a diaphragm pump 1 According to the state of the art. It is a double membrane pump with two membranes 2 ₁ . 2 ₂ , The invention is not, however, a double diaphragm pump 1 limited, but also includes diaphragm pumps with only one membrane.

The double diaphragm pump 1 is powered by the membranes 2 ₁ . 2 ₂ alternately with a medium (not shown) to be printed or reprinted. By comparison, in the case of a membrane pump (not shown) with only one membrane, a return of the membrane during de-printing takes place via a restoring force, in particular a spring.

The double diaphragm pump 1 has two membranes for this 2 ₁ . 2 ₂ on. The membranes 2 ₁ . 2 ₂ each separate one for the drive of the double diaphragm pump 1 provided drive space 3 ₁ . 3 ₂ from a pumping room provided for the conveyance of a fluid 4 ₁ . 4 ₂ , That's what the membranes are for 2 ₁ . 2 ₂ in each case, preferably in full circumference, sealing in a housing 11 the double diaphragm pump 1 edged. In the drive spaces 3 ₁ . 3 ₂ and delivery rooms 4 ₁ . 4 ₂ each is a chamber. In the drive spaces 3 ₁ . 3 ₂ is in each case the medium in the pumping rooms 4 ₁ . 4 ₂ in each case a fluid (not shown) in and diverted.

The two membranes 2 ₁ . 2 ₂ are through a guide 5 , which are each substantially at the center of the membranes 2 ₁ . 2 ₂ fixed to these, interconnected. The guide 5 is rod-shaped and extends in an extension direction 91 , It is straight in and against a direction of displacement 91 in the extension direction 91 runs, displaceable.

At a deformation of the first of the two membranes 2 ₁ . 2 ₂ in the direction of displacement 91 becomes the second of the two membranes 2 ₁ . 2 ₂ also in the direction of displacement 91 deformed. In a deformation of the first membrane 2 ₁ against the direction of displacement 91 deforms the second membrane 2 ₂ also against the direction of displacement 91 ,

Below are the membranes 2 ₁ . 2 ₂ as the first membrane 2 ₁ and as a second membrane 2 ₂ designated. The first membrane 2 ₁ assigned drive space 3 ₁ is the first drive room 3 ₁ , the first membrane 2 ₁ assigned delivery room 4 ₁ is the first pumping room 4 ₁ , The second membrane 2 ₂ assigned drive space 3 ₂ is the second drive room 3 ₂ , the second membrane 2 ₂ assigned delivery room 4 ₂ is the second pumping room 4 ₂ ,

The drive spaces 3 ₁ . 3 ₂ , the pumping rooms 4 ₁ . 4 ₂ and the membranes 2 ₁ . 2 ₂ are preferably arranged surface symmetrical to a plane of symmetry S. Here are the drive spaces 3 ₁ . 3 ₂ on mutually facing sides of the membranes 2 ₁ . 2 ₂ arranged, and the two delivery rooms 4 ₁ . 4 ₂ on opposite sides of the membranes 2 ₁ . 2 ₂ ,

In a ground state G (S. 6 ) are the membranes 2 ₁ . 2 ₂ each not deformed. In a first state of deformation D , the 1 shows in which the first membrane 2 ₁ in the direction of displacement 91 in the first pump room 4 ₁ is deformed into, is the second membrane 2 ₂ in the displacement direction 91 in the second drive room 3 ₂ deformed into it. In a second state of deformation D (S. 2 . 3 . 4 . 6 ), in which the first membrane 2 ₁ against the direction of displacement 91 in the first drive room 3 ₁ is deformed into, is the second membrane 2 ₂ against the direction of displacement 91 in the second pump room 4 ₂ deformed into it. In such a double diaphragm pump 1 become the membranes 2 ₁ . 2 ₂ therefore mutually operated. That the membranes 2 ₁ . 2 ₂ connecting guiding means 5 serves the synchronization of the membranes 2 ₁ . 2 ₂ with each other, so that during a delivery stroke of one of the two membranes 2 ₁ . 2 ₂ a suction stroke of the other membrane 2 ₁ . 2 ₂ is carried out.

The membranes 2 ₁ . 2 ₂ are each deformed by the drive space assigned to them 3 ₁ . 3 ₂ the medium is applied (printing), or by the medium the drive space 3 ₁ . 3 ₂ is withdrawn (de-printing). Suitable mediums are gases, in particular air or inert gases, or liquids. The invention relates especially to pneumatic double diaphragm pumps 1 in which the medium is air or the inert gas. The drive of the double diaphragm pump 1 , in particular the membranes 2 ₁ . 2 ₂ , takes place through the medium.

The removal of the medium from one of the drive spaces 3 ₁ . 3 ₂ is here referred to as printing. For pneumatic diaphragm pumps, it is also referred to as venting.

In a first operating mode I (S. 1 ) becomes the first membrane 2 ₁ printed with the medium. At the same time, the second membrane 2 ₂ entdruckt. In a second operating mode II (S. 2 - 6 ) becomes the second membrane 2 ₂ printed with the medium. At the same time, the first membrane 2 ₁ entdruckt.

The change between the printing and the de-printing leads in each case to a change of direction between the displacement of the guide means 5 in the direction of displacement 91 and moving against the direction of displacement 91 , This is the guide 5 each from the currently printed membrane 2 ₁ . 2 ₂ in or against the direction of displacement 91 drawn. The direction change takes place at a reversal point U , At the reversal point U are the membranes 2 ₁ . 2 ₂ on the guide 5 , that is, here in its center, by the amount of a displacement 90 in or against the direction of displacement 91 postponed. They are then of the ground state G in the first or second deformation state D deformed.

Each in the pump room 4 ₁ . 4 ₂ in deformed membrane 2 ₁ . 2 ₂ reduces the adjoining delivery room 4 ₁ . 4 ₂ , It displaces therefore one in this Förderaum 4 ₁ . 4 ₂ fluid present. The each in the drive room 3 ₁ . 3 ₂ in deformed membrane 2 ₁ . 2 ₂ enlarges this conveyor room 4 ₁ . 4 ₂ , It therefore sucks the fluid into the conveyor 4 ₁ . 4 ₂ into it. A backflow of the fluid when switching between the operating modes I . II is prevented by one or more check valves (not shown). Therefore, even during the time in which the one of the two membranes 2 ₁ . 2 ₂ Fluid in the associated delivery room 4 ₁ . 4 ₂ sucks, with the other of the two membranes 2 ₁ . 2 ₂ Fluid from the associated delivery room 4 ₁ . 4 ₂ promoted. A double diaphragm pump 1 is therefore more efficient to operate than a membrane pump with only one membrane.

The conveyed fluids are preferably liquids, particles permeated liquids, or particles whose flow behavior is similar to that of liquids (particle flow). The present invention mainly relates to double diaphragm pumps 1 used to convey oils, paints and / or varnishes or, where appropriate, gases.

Switching between the operating modes I . II takes place with a double membrane pump 1 in the prior art in each case by a mechanical switching of a switching valve 8th in an end position of the membranes 2 ₁ . 2 ₂ , That is the turning point U always corresponds to a maximum deflection / deformation of the membranes 2 ₁ . 2 ₂ , A purposeful influence on the turning point U is at a mechanical switching of the switching valve 8th therefore not possible.

2 shows a double diaphragm pump according to the invention 1 , The double diaphragm pump 1 has the guide means 5 for connecting the first membrane 2 ₁ with the second membrane 2 ₂ on. The guide 5 is in a leadership 12 of the housing 11 the double diaphragm pump 1 arranged and in and against the direction of displacement 91 displaceable.

The double diaphragm pump 1 has in contrast to the double diaphragm pump 1 of the 1 a sensor 6 on. The sensor 6 is according to the invention for detecting a displacement 90 the membranes 2 ₁ . 2 ₂ provided around which the membranes 2 ₁ . 2 ₂ when moving in or against the direction of displacement 91 from an undeformed ground state G starting in a deformed deformation state D shifts. 2 shows the second deformation state D in the second operating mode.

In the embodiment shown here, the sensor is 6 arranged so that he the displacement 90 of the guide means 5 detected. Because the guide means 5 each center of the membranes 2 ₁ . 2 ₂ arranged, and these are circular here, corresponds to the displacement 90 of guide means 5 in each case the displacement 90 the membranes 2 ₁ . 2 ₂ in its center (not shown). In principle, however, is the detection of the displacement 90 at another point of attack of the membranes 2 ₁ . 2 ₂ conceivable.

Because of the displacement 90 a measure of the deformation of the membranes 2 ₁ . 2 ₂ is, allows the knowledge of the displacement 90 a conclusion and a specific influence on the flow of the fluid, that is, on the amount of fluid delivered in a unit time, and the funded total amount of the fluid.

To the displacement 90 with the sensor 6 to capture, instructs the guide means 5 one in extension direction 91 changing property. The changing property here is a changing contour of the guide means 5 , The guide 5 is one anyway in the double diaphragm pump 1 provided component. For detecting the displacement path 90 the membranes 2 ₁ . 2 ₂ is therefore next to the sensor 6 no additional component on the membranes 2 ₁ . 2 ₂ required. Alternatively or additionally, instead of the changing contour, a changing material property can also be detected. The sensor 6 is then designed to detect this property.

And that shows the guide 5 a fully planned recess 501 on, located in an extension area 54 from an extension beginning 52 to an extension end 53 extends. In the extension area 54 is a diameter D ₅ of the guide means 5 therefore smaller than outside the extension range 54 , The diameter D ₅ changes at the beginning of extension 52 and at the end of extension 53 each leaps and bounds. The extension area 54 is about the middle of the guide means 5 arranged. This is the guide 5 formed of a magnetically conductive material.

The sensor 6 The illustrated embodiment is an electrical coil 61 preferably in or on the guide 12 concentric about an axis of extension (not shown) around which the guide means 5 extends, is arranged. The sink 61 is a component of an electrical resonant circuit (not shown). It extends in the undeformed ground state G the double diaphragm pump 1 essentially along the entire extension area 54 ,

When moving the guide means 5 in or against the direction of displacement 91 becomes the recess 501 out of the coil 61 out or into the coil 61 immersed. Due to the change of the diameter D ₅ changes the inductance of the coil 61 both at the beginning of extension 52 as well as at the end of extension 53 , When immersing the recess 501 in the coil 61 it sinks, with a dive of the recess 501 out of the coil 61 she rises. As a result, the inductance changes continuously when immersed or during immersion. This changes the frequency of the resonant circuit.

The frequency of the resonant circuit is greater, the smaller the inductance. The frequency maximum is therefore here in the basic position G the membranes 2 ₁ . 2 ₂ achieved in the recess 501 completely in the coil 61 is immersed. A deformation of the membranes 2 ₁ . 2 ₂ in or against the direction of displacement 91 leads to a decrease in the frequency. This is thus a measure of the displacement 90 , and therefore for the deformation of the membranes 2 ₁ . 2 ₂ , Because the frequency in the basic position G the membranes 2 ₁ . 2 ₂ is maximum, is the basic position G clearly determinable on the basis of the frequency. By comparison of the detected displacement path 90 with a reference curve of the frequency, which represents the change of the frequency over a reference path, is the displacement path 90 clearly determinable.

An analogous change in the frequency of the resonant circuit is also due to a change in the magnetic conductivity of the guide means 5 in extension direction 91 reachable. This can be achieved, for example, by using materials with different permeability. For example, in this case, the material of the guide means 5 in the extension area 54 a smaller permeability than the material of the guide means 5 on both sides outside the extension area 54 ,

The recorded displacement 90 is for controlling the double diaphragm pump 1 available. For this, the diaphragm pump 1 a control unit. An electrical circuit board 7 that includes the control unit is shown schematically here.

The control unit regulates a reversal point U between the first operating mode I and the second mode of operation II the double diaphragm pump 1 , This is the switching valve 8th used. The scheme is in 6 explained in more detail. The amount of the displacement 90 at the turning point U is hereafter as the hub of the membrane 2 ₁ . 2 ₂ designated.

3 shows a further embodiment of a double diaphragm pump according to the invention 1 , The for the detection of the displacement 90 of the guide means 5 used sensor 6 Here is a Hall sensor 63 ,

The guide 5 points in the extension area 54 a variety of full around the guide means 5 arranged grooves 501 on, so it's here in the extension area 54 is formed wavy. The changing property is therefore here also a changing contour of the guide means 5 ,

In this measurement of the displacement 90 intersperses the guide means 5 a magnetic field (not shown). The turns 501 on the guide 5 cause a change in the magnetic field strength of the magnetic field, so that an output voltage of the Hall sensor 63 , that's the measurement signal M , the Hall sensor 63 delivers, changes.

However, with this arrangement of the sensor 6 only an incremental detection of the displacement 90 by counting the number of turns 501 possible. To the displacement 90 Using this measurement to capture concrete, is a position marker P required as a reference point on the guide 5 is arranged.

As a position marker P is, for example, one opposite to the remainder 501 differently formed, preferably longer or deeper recess 502 formed by a pulse length and / or an amount of the measuring signal M changes. Alternatively, the position marker P can be formed as a material change, which can be detected by a further sensor (not shown). In these embodiments, the position marker P is preferably in the center of the guide means 5 arranged. The displacement path 90 is detected by detecting the relative path to the position mark P.

4 shows a section of a further embodiment of a double diaphragm pump according to the invention 1 , On or in the guide 5 is a permanent magnet 504 arranged.

As a sensor 6 for detecting the displacement path 90 suitable here is a magnetoresistive sensor 62 or a Hall sensor 63 , The sensor 6 detects the magnetic field (not shown) of the permanent magnet 504 , in particular a reduction or increase in the magnetic field strength (not shown) during displacement of the guide means 5 in or against the direction of displacement 91 , The change in the magnetic field strength is a measure of the amount and the direction of the displacement 90 , The displacement path 90 is therefore determinable by comparison with a reference curve of the magnetic field strength, which represents the change in the magnetic field strength over the reference path. The arrangement allows an absolute detection of the current position of the guide means 5 without further position markings. The guide 5 Incidentally, it is preferably made of a non-ferromagnetic material to influence the magnetic field by the guide means 5 to exclude as possible. The changing property here is therefore a changing material property of the management tool 5 shows a linear variable differential transformer 64 (LVDT) acting as a sensor 6 for detecting the displacement path 90 is usable.

The linear variable differential transformer 64 includes a centrally located exciter coil 601 , as well as two on both sides of the exciter coil 601 arranged secondary coils 602 . 603 , The secondary coils 602 . 603 are symmetrical to the exciter coil 601 arranged opposite to each other aligned, and electrically connected to each other. At the unconnected ends K2 . K3 the secondary coils 602 . 603 the measurement signal S is tapped. The measurement signal S is preferably a differential voltage at the secondary coils 602 . 603 declining voltage.

For detecting the displacement path 90 gets to the primary coil 601 an alternating voltage with constant amplitude and constant frequency applied. The frequency is preferably 1 to 10 kHz.

The guide 5 preferably has a soft iron core 503 up, extending over an extension range 54 of the guide means 5 extends. The changing property is therefore here also a changing material property of the management tool 5 , The soft iron core 503 is arranged so that it is the primary coil 601 in the ground state G interspersed. He is also in the ground state G in the middle of the secondary coils 602 . 603 arranged. In the ground state G the arrangement is therefore symmetrical. This will lift up the coils 601 . 602 . 603 each falling voltages, and there is no measurement signal M that is, no differential voltage at the linear variable differential transformer 64 ,

When moving the guide means 5 in or against the direction of displacement 91 the arrangement is made by moving the soft iron core 503 unbalanced. Then the soft iron core intersperses 503 one of the two secondary coils 602 . 603 more than the other of the two secondary coils 602 . 603 , This is the secondary coils 602 . 603 decreasing voltage varies greatly, and there is a difference voltage as a measurement signal M , The amount of the differential voltage is a measure of the amount of the displacement 90 , the sign shows the shift direction 91 at.

6 shows a further embodiment of a double diaphragm pump according to the invention 1 , The double diaphragm pump 1 is here in the ground state G shown in which the membranes 2 ₁ . 2 ₂ are undeformed. The double diaphragm pump 1 has the sensor 6 for detecting the displacement path 90 the membranes 2 ₁ . 2 ₂ on. The sensor 6 detects the displacement 90 of the guide means 5 for that the changing property 50i in the extension area 54 having. This is indicated by a dashed line of the guide means 5 shown schematically.

The membranes 2 ₁ . 2 ₂ separate each drive space 3 ₁ . 3 ₂ , in which the medium for driving the double diaphragm pump 1 can be introduced and redirected from the delivery room 4 ₁ . 4 ₂ , in which the fluid to be pumped on and is again diverted. The introduction and discharge of the fluid in the first or in the second delivery chamber 4 ₁ . 4 ₂ is here by arrows F ₁₁ . F ₁₂ . F ₂₁ . F ₂₂ shown schematically.

The drive takes place with the medium, here preferably air, alternately either in the first drive space 3 ₁ or in the second drive space 3 ₂ is initiated. This is the double diaphragm pump 1 to a medium supply 10 connected, for example, to a compressed air compressor. A supply line 101 connects the medium supply 10 with the switching valve 8th , The changeover valve 8th is over a first supply line 1011 to the first drive room 3 ₁ connected, and via a second supply line 1012 to the second drive space 32 ,

As a changeover valve 8th For example, a 5/2-way valve is used. The 5 / 2 -Wegeventil internally has five internal lines to which the supply line 101 and the first and second leads 1011 . 1012 can be connected. It allows two valve positions. In the first valve position, the medium is through the supply line 101 in the first supply line 1011 passed and the first drive space 3 ₁ printed with the medium. At the same time, the second supply line 1012 , and with it the second drive space 3 ₂ , Connected to an internal second vent line of the switching valve, so that the medium to the second drive space 3 ₂ can escape and this is therefore de-pressurized / vented. In the first valve position is the double diaphragm pump 1 therefore in the first operating mode I ,

In the second valve position, the medium is through the supply line 101 in the second supply line 1012 passed and the second drive space 3 ₂ printed with the medium. At the same time, the first supply line 1011 , and with it the first drive room 3 ₁ , to an internal first vent line of the switching valve 8th connected so that the medium is the first drive space 3 ₁ can escape and this is therefore de-pressurized / vented. In the second valve position is the double diaphragm pump 1 therefore in the second operating mode II ,

Alternatively, as shown here, a 5/3-way valve 8th usable, which allows a third valve position in which the supply of the medium is interrupted. The supply line 101 is then neither with the first nor with the second supply line 1011 . 1012 connected. One 5 / 3 - directional valve 8th allows pressure equalization between the drive spaces 3 ₁ . 3 ₂ the double diaphragm pump 1 before between the printing of a drive space 3 ₁ . 3 ₂ and printing the other drive space 3 ₁ . 3 ₂ is switched. The first and the second supply line 1011 . 1012 will be shorted, as shown here. This requires the drive spaces 3 ₁ . 3 ₂ not completely vented, so that a saving of compressed air is possible.

The stroke of the membranes 2 ₁ . 2 ₂ That's the way to move 90 the membranes 2 ₁ . 2 ₂ at the turning point U , also influences each in the pumping rooms 4 ₁ . 4 ₂ sucked amount of the fluid. By changing the turning point U Therefore, the flow rate of the fluid, and the number of strokes, which is needed to promote a total amount of the fluid influenced.

The double membrane pump according to the invention 1 therefore, provides the reversal point U the membranes 2 ₁ . 2 ₂ to control.

When commissioning the double diaphragm pump 1 are the pumping rooms 4 ₁ . 4 ₂ still empty. Therefore, then large strokes are desirable to the largest possible suction pressure / vacuum in the delivery chambers 4 ₁ . 4 ₂ to effect and aspirate as much fluid. The membranes become 2 ₁ . 2 ₂ but strongly deformed, and thus heavily loaded, so that their life significantly reduced. During operation, shorter strokes are desirable to increase the life of the membranes 2 ₁ . 2 ₂ to extend.

Therefore, the double diaphragm pump according to the invention sees 1 prefers the reversal point U the membranes 2 ₁ . 2 ₂ depending on an operating status of the double diaphragm pump 1 to control. In the process, a start-up operation is initiated when the double-diaphragm pump is started up 1 and the operating status of continuous operation during operation of the double diaphragm pump 1 distinguished. The reversal point U depends on the operating status of the double diaphragm pump 1 preset or calculated automatically.

This is indicated by the double diaphragm pump 1 an internal electrical control unit 7 on, which includes a programmable central processing unit. The programmable central processing unit is controlled by a microcontroller .mu.C educated. In principle, instead of the internal electrical control unit 7 Also, an external electrical control unit available, or, in particular for each operating status, in each case a manual input of the reversal points U at the double diaphragm pump 1 conceivable.

To the double diaphragm pump 1 to control displacement-dependent, is the displacement 90 the membranes 2 ₁ . 2 ₂ with the sensor 6 detected. The recorded displacement 90 is with a set reversal point U compared. If the detected displacement 90 the turning point U is equal to or exceeds the diaphragm pump 1 from the first operating mode I in the second operating mode II or switched back.

This is done by the electrical control unit 7 the changeover valve 8th switches. The valve position is when using a 5/2-way valve as a changeover valve 8th from the first to the second valve position or switched back. A control signal for switching the switching valve 8th is schematically by an arrow S shown. For a 5/3-way valve, the control unit controls 7 the changeover valve 8th such that it temporarily remains between the first and second valve position in the third valve position.

The sensor 6 detects an analogue measurement signal M , The evaluation is done but preferably clocked.

In this process, the reversal points U for example, manually preset depending on the operating status. The use of the electrically controllable diverter valve 8th then allows automatic adjustment of the reversal points U , It is in the start-up a long stroke, ie a later reversal point U , provided, and in continuous operation a short stroke, ie an early reversal point U , A change between the operating status occurs, for example, by changing the reversal points U after a fixed time.

The use of an internal electrical control unit 7 but also allows detection of the operating status based on the measurement signal M , In this case, a property of the fluid is used, on the basis of which the measurement signal M during operation of the diaphragm pump 1 changes. A time-dependent or manual switching between the operating status is then not required.

When starting the double diaphragm pump 1 this is in the start-up operating status. In this operating status are the pumping rooms 4 ₁ . 4 ₂ , Which are provided for conveying a fluid, and in which the fluid is respectively introduced and discharged, initially still free from the fluid to be delivered. For pneumatically operated diaphragm pumps is located in the delivery chambers 4 ₁ . 4 ₂ instead, for example, air or an inert gas. However, with continued operation of the double diaphragm pump 1 more and more of the fluid to be pumped into the pumping rooms 4 ₁ . 4 ₂ promoted. As a result, the compressibility of the change in the delivery rooms 4 ₁ . 4 ₂ fluid and the resistance with which this the membranes 2 ₁ . 2 ₂ counteracts. The changing resistance causes a change in the frequency of the measurement signal M , as well as a changing waveform of the measurement signal M ,

7 shows in (a) and (b) each schematically the course of the measurement signal M , in (a) at one in the delivery room 4 ₁ . 4 ₂ located, not or almost incompressible fluid, and in (b) at a in the delivery room 4 ₁ . 4 ₂ located compressible fluid.

In a compressible medium, in particular a gas such as air, the resistance increases, with the medium of each of the membrane 2 ₁ . 2 ₂ when compressing counteracts. This will be the displacement 90 around the membrane 2 ₁ . 2 ₂ in a time unit in the respective delivery room 4 ₁ . 4 ₂ moved in, smaller. The course of the measuring signal M is therefore arcuate. this shows 7 (b) ,

For a medium that is not or significantly less compressible in the delivery room 4 ₁ . 4 ₂ On the other hand, the resistance does not change or almost does not change. The course of the measuring signal M is then about straight. this shows 7 (a) ,

Shown is the respective displacement 90 over time 99 , Starting from the ground state G becomes the guiding agent 5 in the first operating mode I by applying the first drive space 3 ₁ with the medium around the displacement 90 in the direction of displacement 91 shifted, with the first membrane 2 ₁ in the pump room 4 ₁ is deformed into it. The second membrane 2 ₂ is simultaneously in the second drive space 3 ₂ deformed into it. At the reversal point U1 , the first reversal point here U1 is designated, the switching valve 8th in the second operating mode II switched, so now the second drive space 3 ₂ is printed with the medium. The second membrane 2 ₂ will then be against the direction of displacement 91 in the second pump room 4 ₂ deformed into it. This is the first membrane 2 ₁ in the first drive room 3 ₁ deformed into it until the switching valve 8th the double membrane pump 1 at the turning point U2 , the second reversal point here U2 is designated, in the first operating mode I switches back. It is getting more and more of the fluid to be pumped into the pumping rooms 4 ₁ . 4 ₂ pumped in until the pumping rooms 4 ₁ . 4 ₂ are filled in the operating status continuous operation substantially with the fluid to be delivered.

During startup, the course of the measurement signal corresponds M therefore in the delivery rooms 4 ₁ . 4 ₂ located, compressible fluid such as air about that of 7 (b) , If a fluid that is considerably less compressible than air is delivered, For example, a liquid, the course of the measurement signal M with its increasing share in the production areas 4 ₁ . 4 ₂ straight. In addition, the switching frequency decreases with increasing proportion of less compressible fluid in the delivery chambers 4 ₁ . 4 ₂ , If the delivery chambers are completely filled with the less compressible fluid to be delivered, the switching frequency and the course of the periods of the measurement signal are approximately constant.

Also the course of the speed of the membranes 2 ₁ . 2 ₂ and / or their acceleration allow in a similar way a conclusion on the operating status. This is shown by the 7 (c) and (d). 7 (c) shows the course of the velocity of the membranes 2 ₁ . 2 ₂ at one in the pump room 4 ₁ . 4 ₂ located, not or almost incompressible fluid, and 7 (d) at one in the pump room 4 ₁ . 4 ₂ located compressible fluid. In a non-compressible or almost incompressible fluid in the delivery chambers 4 ₁ . 4 ₂ is the speed of the membranes 2 ₁ . 2 ₂ in the first and second operating modes I . II about constant. On the other hand, it drops in the first and second operating modes I . II with a compressible fluid in the delivery chambers 4 ₁ . 4 ₂ with increasing deformation of the membranes 2 ₁ . 2 ₂ from.

As the service life increases, the deformation behavior of the membranes also changes 2 ₁ . 2 ₂ , It has been shown that by comparing the course of the measuring signal M , the speed 900 the membranes 2 ₁ . 2 ₂ and / or their acceleration with reference signals, a conclusion on the condition, in particular the remaining remaining life of the membranes 21 . 22 , is possible.

In addition, the curves of the measurement signal M , the speed 900 the membranes 2 ₁ . 2 ₂ and / or their acceleration already before a membrane rupture of one of the two membranes 2 ₁ . 2 ₂ a double diaphragm pump 1 unbalanced. The comparison of the signal curves in the operating modes I . II therefore allows a conclusion on an imminent membrane rupture, and on the damaged membrane 2 ₁ . 2 ₂ , The control unit 7 then provides a switch to an operating status error mode, in which a warning is issued to the operator, or stopping the double diaphragm pump 1 ,

In the case of a membrane rupture, this causes the membranes to be driven 2 ₁ . 2 ₂ used medium in the broken membrane 2 ₁ . 2 ₂ associated delivery room 4 ₁ . 4 ₂ , This changes the compressibility of the delivery chamber 4 ₁ . 4 ₂ located fluid. The diaphragm fracture itself is therefore also based on the signal characteristics of the measurement signal M , the speed 900 the membranes 2 ₁ . 2 ₂ , their acceleration and / or the switching frequency recognizable.

The 8th - 11 show each extended embodiments of the double diaphragm pump 1 of the 6 ,

The double diaphragm pump 1 of the 8th differs from the double diaphragm pump the 6 through a changeover valve 8th upstream throttle 81 , The throttle 81 is designed here as an electrically controllable proportional valve, and in the supply line 101 the medium to the switching valve 8th arranged. It is with the control unit 7 electrically controllable and allows a change in the diameter of the supply line 101 , As a result, the amount of the medium, that is the volume flow, and the pressure of the switching valve 8th supplied medium with the control unit 7 controllable. The control unit 7 controls the volume flow so that the membranes 2 ₁ . 2 ₂ be operated at about the same speed. In addition, an operating status-dependent control of the throttle 81 preferred in which the volume flow of the medium in the starting operation is greater than in continuous operation. As a result, a higher intake volume can be reached in the starting operation.

The double diaphragm pump 1 of the 9 differs from the double diaphragm pump the 8th by a first pressure sensor 65 that is between the switching valve 8th and the throttle 81 is arranged. With the pressure sensor 65 the pressure of the medium is measurable. The pressure sensor 65 makes with the throttle 81 a control loop. The control unit 7 is then provided for the throttle 81 depending on the pressure sensor 65 measured pressure signal so that a pressure of the medium on the membranes 2 ₁ . 2 ₂ is constant. At a changing, for example, fluctuating, operating pressure of the medium supply 10 is with this double diaphragm pump 1 nevertheless a roughly constant pressure on the membranes 2 ₁ . 2 ₂ reachable.

The double diaphragm pump 1 of the 10 differs from the double diaphragm pump the 9 through a second pressure sensor 66 provided for measuring an operating pressure of the medium, and in the supply line 101 and in front of the throttle 81 is arranged. The control unit 7 this double diaphragm pump 1 is intended to switch off the supply of the medium when falling below a threshold pressure. The detection of the operating pressure allows control of the air distribution in a supply network and a prioritization of several connected to the supply network consumer / double diaphragm pumps 1 ,

The double diaphragm pump 1 of the 11 is different from the double diaphragm pump 1 of the 10 through a cross-ventilation valve 82 in Connection with a 5/3-way valve 8th which is closed in the middle position. The cross ventilation valve 82 is between the first supply line 1011 the medium to the first drive space 3 ₁ the first membrane 2 ₁ and a second supply line 1012 the medium to the second drive space 3 ₂ the second membrane 2 ₂ arranged. With the cross ventilation valve 82 is a pressure equalization between the two supply lines 1011 . 1012 the drive spaces 3 ₁ . 3 ₂ possible. This allows the consumption of the medium of the double diaphragm pump 1 be significantly reduced. The control unit 7 this double diaphragm pump 1 controls the cross ventilation valve 82 so it's the first lead 1011 with the second supply line 1012 in each case between switching from the first to the second operating mode I . II or back for a short time.

The method allows automatic detection of the operating status of the diaphragm pump 1 based on the measurement signal M , Through an analysis of the displacement path 90 , the speed 900 the membrane 2 ₁ . 2 ₂ , the acceleration of the membrane 2 ₁ . 2 ₂ and / or the switching frequency of the diaphragm pump 1 is the turning point U the changeover valve 8th Operationally controllable. In addition, such an analysis allows a conclusion on the condition of the membrane 21 . 22 ,

LIST OF REFERENCE NUMBERS

1

diaphragm pump

11

casing

12

guide

2 ₁ , 2 ₂

membrane

3 ₁ , 3 ₂

drive space

4 ₁ , 4 ₂

delivery chamber

5

guide means

501

recess

502

waviness

503

Soft iron core

504

permanent magnet

50i

Changing feature of the management tool

52

extension beginning

53

extending end

54

extension area

6

sensor

61

Kitchen sink

601

primary coil

602, 603

secondary coil

62

magnetoresistive sensor

63

Hall sensor

64

linear variable differential transformer (LVDT)

65, 66

Pressure measuring sensor

7

Internal electrical control unit

8th

Equipment, changeover valve

81

Operating equipment, proportional valve, throttle

82

Equipment, cross-ventilation valve

9

extension axis

90

Displacement, extension direction

99

Time

900

Speed of the membrane

900 ₁ , 900 ₂

Speed of the diaphragm in the first / second operating mode

91

displacement direction

10

medium supply

101

supply line

1011, 1012

First supply line, second supply line

I

First operating mode

II

Second operating mode

G

ground state

D

deformation state

K2, K3

End of the coil

D ₅

Diameter of the guide means

e

plane of symmetry

M

measuring signal

S1, S2, S3

First, second, third control signal

D1, D2

First, second pressure measurement signal

U, U1, U2

Reversal point, first reversal point, second reversal point

.mu.C

Programmable central processing unit, microcontroller

F ₁₁ , F ₁₂ ,

Introducing and discharging the fluid into the first or second

F ₂₁ , F ₂₂

delivery chamber

Claims (14)

Method for controlling a diaphragm pump (1), in particular a double diaphragm pump, in which • a sensor (6) measures a measuring signal (M), in particular continuously or clocked; which detects a displacement path (90) of a membrane (2 ₁ , 2 ₂ ) which separates a delivery chamber (4 ₁ , 4 ₂ ) from a drive space (3 ₁ , 3 ₂ ); and in which • a control unit (7) of the diaphragm pump (1) ◯ detects an operating status of the diaphragm pump (1) on the basis of the measuring signal (M), ◯ sets or calculates a reversal point (U) as a function of the detected operating status of the diaphragm pump (1) , and ◯ a changeover valve (8) is controlled so that this the membrane pump (1) from a first operating mode (I) in which the drive space (3 ₁ , 3 ₂ ) is printed with a medium in a second operating mode (II) in which the drive space (3 ₁ , 3 ₂ ) is de-pressurized or switches back when the detected displacement path (90) is equal to or greater than the reversal point (U), characterized in that the control unit (7) determines the reversal point (U) as a function of at least two operating states, wherein the reversal point (U) is provided in a continuous operating status with a smaller stroke than in a start-up operating status. Method according to Claim 1 , characterized in that the operating status is detected by • the control unit (7) from the measurement signal (M), in particular from at least two successively detected values of the measurement signal (M), calculated a switching frequency of the diaphragm pump (1), and the operating status based the switching frequency is determined, and / or • the control unit (7) determines the operating status by a comparison process of the measuring signal (M) with reference signals, and / or • the control unit (7) from the measuring signal (M) a speed and / or an acceleration the diaphragm (2 ₁ , 2 ₂ ) calculated, and detects the operating status by a comparison process of the waveform of the speed and / or the waveform of the acceleration with reference signals. Method according to Claim 1 or 2 , characterized in that the control unit (7) controls the switching valve (8) or a shut-off valve upstream of the switching valve (8) so that a supply of the medium into the drive space (3 ₁ , 3 ₂ ) between the switching from the first operating mode (I) is briefly interrupted in the second operating mode (II) or back, in particular when a preset or calculated switching frequency is exceeded. Method according to one of the preceding claims, characterized in that the control unit (7) controls the switching valve (8) or a shut-off valve upstream of the switching valve (8) so that the supply of the medium is terminated when a preset or calculated number strokes of the membrane (2 ₁ , 2 ₂ ), or a preset flow rate of a with the diaphragm pump (1) to be delivered fluid is reached. Method according to one of the preceding claims, characterized in that the diaphragm pump (1) comprises a changeover valve (8) upstream throttle (81), in particular an electrically controllable proportional valve, for changing a volume flow of the medium, and the control unit (7), the throttle (81) controls so that the volume flow during start-up operation is greater than in continuous operation. Method according to Claim 5 , characterized in that the control unit (7) controls the throttle (81) so that the volume flow of the medium in continuous operation is constant. Method according to Claim 5 or 6 , characterized in that the diaphragm pump (1) comprises a first pressure sensor (65) disposed between the switching valve (8) and the throttle (81), wherein the control unit (7) the throttle (81) in dependence on the the pressure sensor (65) measured pressure signal controls so that a pressure of the medium to the membrane (2 ₁ , 2 ₂ ) is constant. Method according to one of Claims 5 to 7 , characterized in that the membrane pump (1) comprises a second pressure sensor (66) for measuring an operating pressure of the medium, which is upstream of the throttle (81), wherein the control unit (7) interrupts the supply of the medium falls below a limit pressure or shuts off , Method according to one of the preceding claims, characterized in that the diaphragm pump (1) is a double diaphragm pump, and that it comprises a transverse venting valve (82) which between a first supply line (1011) of the medium to the first drive space (3 ₁ ) of the first membrane (2 ₁ ) and a second supply line (1012) of the medium to the second drive space (3 ₂ ) of the second diaphragm (2 ₂ ) is arranged, wherein the control unit (7) controls the cross-ventilation valve (82) so that it the first supply line ( 1011) temporarily connects to the second supply line (1012) between switching from the first operating mode (I) to the second operating mode (II) or back. Method according to one of the preceding claims, characterized in that the control unit (7) detects an asymmetry of the measurement signal (M) and / or the signal profile of the speed and / or the acceleration by a comparison process with reference signals, in particular as maintenance information. Method according to one of the preceding claims, characterized in that the diaphragm pump (1) is a double diaphragm pump, and the control unit (7) an asymmetry of the measurement signal (M) and / or the signal waveform of the speed and / or the acceleration by a comparison process of a signal component detected in the first operating mode (I) with a signal component in the second operating mode (II). Method according to one of the preceding claims, characterized in that the diaphragm pump (1) has a user interface, and the control unit (7) maintenance information and / or operating data such as • the displacement of the membrane, • the reversal point of the membrane, • the operating status of the diaphragm pump, • The currently delivered quantity of fluid, • The flow rate of the fluid, • The pumped quantity of medium, • The average pressure of the medium on the diaphragm, • The operating pressure of the medium / medium supply, • The current, still required number and / or total number of strokes the membrane, • The average remaining life of the membrane, • The warning that the membrane deforms asymmetrically. at the user interface. Diaphragm pump (1), in particular double membrane pump, which is designed to carry out the method according to one of the preceding claims, with at least one membrane (2 ₁ , 2 ₂ ) having a delivery space (4 ₁ , 4 ₂ ) from a drive space (3 ₁ , 3 ₂ ) separates; A sensor (6) for measuring a measurement signal (M) which detects a displacement path (90) of the diaphragm (2 ₁ , 2 ₂ ); • An electric switching valve (8), which is provided, the diaphragm pump (1) in a reversal point of the membrane (2 ₁ , 2 ₂ ) of a first operating mode (I), in which the drive space (3 ₁ , 3 ₂ ) with a medium is printed, in a second operating mode (II) in which the drive space (3 ₁ , 3 ₂ ) is de-pressurized, or switch back; and a control unit (7) for controlling the switching valve (8), characterized in that the control unit (7) controls the turning point (U) in response to at least two operating statuses so that the turning point (U) in a continuous operation mode with a smaller one Hub is provided as in a start-up operation status. After the diaphragm pump Claim 13 , characterized in that it comprises a user interface for outputting operating data, service and / or maintenance information.

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