EP3115607B1 - Double membrane pump - Google Patents

Description

Technical area

The invention relates to a double-membrane pump for conveying fluid, such as paint or paint.

State of the art

From the publication DE 38 76 169 T2 is a double diaphragm known. In this pump, a first and a second pumping chamber and a first and a second pressure chamber are provided, wherein the first pumping chamber and the first pressure chamber are separated by a first diaphragm and the second pumping chamber and the second pressure chamber by a second diaphragm. The two membranes are mechanically connected by means of a shaft. The shaft extends axially along an axis through the center of each of the membranes and is secured to the membranes by means of two plates, respectively. Thus, the two diaphragms move in unison when the pump is operating. When the first pressure chamber is pressurized, the associated membrane is caused to compress the fluid in the associated first pumping chamber. The fluid is thus pushed out of the first pumping chamber. At the same time, the membrane associated with the second pumping chamber is deflected, so that fluid is drawn into the second pumping chamber. The membranes are moved back and forth in unison (synchronous to each other), to alternately fill the pumping chamber and evacuate.

However, this double diaphragm pump thus formed has several disadvantages, which will be explained below.

By the time the first diaphragm reaches the end of its working stroke (dead center), the delivery pressure in the first pumping chamber drops significantly. Since the second membrane has also reached its dead center in this phase, the second pumping chamber is also not or not yet available for pushing out the fluid. This has the consequence that the delivery pressure is very low or zero until the shaft undergoes a reversal of motion and ensures that the second diaphragm builds a delivery pressure in the second pumping chamber. Considered over time, this behavior on the outlet side of the double-diaphragm pump leads to periodically recurring discharge pressure drops and thus to more or less severe delivery interruptions.

This double diaphragm pump has another disadvantage. The delivery pressure depends on the material (rigidity) of the diaphragm and thus changes over the stroke. This results in the fluid being expelled at the beginning of the ejection phase at high pressure, among other things because the diaphragm is in the deflected position and is thus under tension. Subsequently, the ejection pressure decreases and towards the end of the stroke, not only the fluid, but also the membrane must be pressed into the end position. Only when the other membrane changes from the suction phase to the ejection phase, the fluid is ejected again at a high pressure. Over time considered, the feed pressure instead of a rectilinear an undesirable sawtooth-shaped course.

Presentation of the invention

An object of the invention is to provide a double diaphragm pump in which the abovementioned disadvantages are avoided or at least minimized.

Advantageously, the double diaphragm pump according to the invention generates a delivery flow with an approximately constant delivery pressure.

As a rule, a pump which generates a delivery pressure which is not as constant as the double membrane pump according to the invention must be followed by a pulsation damper. A further advantage of the double membrane pump according to the invention is that it manages without such a pulsation damper.

The double diaphragm pump according to the invention can also be used, for example, for a two-component spray system. The A component can be color and the B component hardener. In such a two-component spray system, often the pump that pumps the A component is used as the master and the B component is added. This can be done by opening the material valve for the B-component at certain times for a certain period of time and bringing the B-component in the delivery hose to the A-component. However, this assumes that the B component is pumped at a higher pressure than the A component.

Otherwise, the B component will not get into the delivery hose. If the pumps for the A and B components have a sawtooth pressure curve, the metered addition of the B component is not possible until the pressure for the B component is higher than for the A component. In this case, you have to wait until the pressure for the B component is sufficiently high. As a result, the B component can not be added at any time. However, because the double diaphragm pump according to the invention has a constant pressure curve, this disadvantage can be avoided with it. The object is achieved by a double diaphragm pump having the features specified in patent claim 1.

In the double diaphragm pump according to the invention, a first diaphragm is provided, which forms a wall of a first pumping chamber, wherein the first diaphragm can be moved by means of a first drive means. In addition, a second membrane is provided, which forms a wall of a second pumping chamber, wherein the second membrane is movable by means of a second drive means. In addition, a control is provided for the drive means, which is designed and operable to control the two drive means depending on one or more conditions.

The first and the second drive means are designed so that they can be operated independently of each other. The control for the drive means can thus control the first drive means independently of the second drive means. Thus, from the perspective of the controller two drive means two drive means that do not affect each other.

Advantageous developments of the invention will become apparent from the features indicated in the dependent claims.

In one embodiment of the double diaphragm pump according to the invention, the condition is based on time, pressure, travel and / or position.

In a further embodiment of the double-diaphragm pump according to the invention, the control is designed and operable so that it already provides pressure build-up in the other pumping chamber before the membrane in one pumping chamber has reached its front dead center. As the front dead center of the membrane is meant here that in which the volume in the pump chamber belonging to this membrane is minimal.

In another embodiment of the double membrane pump according to the invention, the controller is designed and operable such that, when the negative pressure in the one pumping chamber falls below a certain threshold value, it ensures a buildup of pressure in this pumping chamber.

In a further development of the double-diaphragm pump according to the invention, the controller is designed and operable such that it controls the two drive means offset in time from one another so that the two diaphragms move with a time offset from one another.

In another development of the double-diaphragm pump according to the invention, the controller is designed and operable such that it controls the two drive means isochronously relative to one another.

In the case of the double diaphragm pump according to the invention, a first pressure chamber may be provided which is separated from the first pumping chamber by the first diaphragm. In addition, a second pressure chamber may be provided which is separated from the second pumping chamber by the second diaphragm.

In addition, in the case of the double membrane pump according to the invention it can be provided that at least one of the drive means is a drive means which can be operated with compressed air.

Advantageously, in the double-diaphragm pump according to the invention, the drive means each have a piston which is movable in a cylinder or a diaphragm which can be moved by compressed air.

It may also be advantageous if, in the double membrane pump according to the invention, the drive means each have a piston which is movable in a cylinder or a membrane which is movable in at least one direction with a resilient element.

In the case of the double diaphragm pump according to the invention, the drive means can each have at least one sensor for detecting the end position.

In the case of the double membrane pump according to the invention, the controller can also be designed and operable in this way, that it controls the two drive means depending on the signal from the sensor.

In a further development of the double-diaphragm pump according to the invention, the controller is designed and operable such that it brings about a reversal of the direction of the drive means when the sensor is actuated in the first drive means and the sensor in the second drive means.

In another development of the double-diaphragm pump according to the invention, the first and the second pumping chambers each have a pumping chamber outlet, which open into a common pump outlet.

In an additional development of the novel double membrane pump, the membranes are mechanically biased at least before the delivery phase. Thus, the pressure curve can be further optimized and fine-tuned.

In one embodiment of the double-diaphragm pump according to the invention, the controller has a differential valve which in one position connects a compressed-air source to the first drive means so that the drive means moves the first diaphragm so that a negative pressure is created in the first pumping chamber. In the other position, the differential valve connects the source of pressurized air to the second drive means such that it moves the second diaphragm to create a vacuum in the second pumping chamber.

The inventive double diaphragm pump also has the advantage that it starts up easily, regardless of the position in which the pistons and the membranes are at the time of switch-on. Even if air is sucked in instead of material at the material inlet, the double-membrane pump according to the invention runs smoothly. This condition may occur, for example, during initial start-up when the pump is still empty or when the fluid reservoir is empty.

In addition, the double-diaphragm pump can be designed so that an undesirable stoppage of the pump is reliably avoided. The double diaphragm pump can for this purpose the changeover valve with differential piston and a pilot valve, such as a flip-flop valve have.

In a further embodiment of the double diaphragm pump according to the invention, the differential valve in one position connects the compressed air source with the second drive means such that it moves the second diaphragm so that an overpressure is created in the second pumping chamber. In the other position, the differential valve connects the source of pressurized air to the first drive means so as to move the first diaphragm to create an overpressure in the first pumping chamber.

Finally, it can be provided in the inventive double diaphragm pump, that the controller has a flip-flop valve which is controllable with limit switches and which controls the differential valve.

The control by means of the limit switches has the advantage that the end positions of the piston or the membranes can be detected in a simple and secure manner. Thus, if necessary, it can be ensured that the two membranes perform the entire stroke.

Brief description of the drawings

Figur 1

zeigt eine erste mögliche Ausführungsform der erfindungsgemässen Doppelmembranpumpe in einer dreidimensionalen Ansicht.

Figur 2

zeigt die erste Ausführungsform der erfindungsgemässen Doppelmembranpumpe ohne Armaturen in einer dreidimensionalen Ansicht.

Figur 3

zeigt die erste Ausführungsform der erfindungsgemässen Doppelmembranpumpe im Längsschnitt von der Seite.

Figur 4

zeigt die erste Ausführungsform der erfindungsgemässen Doppelmembranpumpe im Längsschnitt von oben.

Figur 5

zeigt die erste Ausführungsform der erfindungsgemässen Doppelmembranpumpe im Querschnitt.

Figur 6

zeigt den Aufbau der ersten Ausführungsform der erfindungsgemässen Doppelmembranpumpe in einem Blockschaltbild.

Figur 7

zeigt den Aufbau einer zweiten Ausführungsform der erfindungsgemässen Doppelmembranpumpe in einem Blockschaltbild.

Figur 8

zeigt den Aufbau einer dritten Ausführungsform der erfindungsgemässen Doppelmembranpumpe in einem Blockschaltbild.

Figur 9

zeigt in einem Diagramm den zeitlichen Verlauf der einzelnen Drücke und des Gesamtdrucks.

Figur 10

zeigt in einem Diagramm den zeitlichen Verlauf der einzelnen Drücke und des Gesamtdrucks.

Figur 11

zeigt in einem Diagramm den zeitlichen Verlauf der einzelnen Drücke und des Gesamtdrucks.

In the following the invention with several embodiments will be explained with reference to several figures.

FIG. 1

shows a first possible embodiment of the inventive double diaphragm pump in a three-dimensional view.

FIG. 2

shows the first embodiment of the inventive double diaphragm pump without fittings in a three-dimensional view.

FIG. 3

shows the first embodiment of the inventive double membrane pump in longitudinal section from the side.

FIG. 4

shows the first embodiment of the inventive double diaphragm pump in longitudinal section from above.

FIG. 5

shows the first embodiment of the inventive double diaphragm pump in cross section.

FIG. 6

shows the structure of the first embodiment of the inventive double diaphragm pump in a block diagram.

FIG. 7

shows the structure of a second embodiment of the inventive double diaphragm pump in a block diagram.

FIG. 8

shows the structure of a third embodiment of the inventive double diaphragm pump in a block diagram.

FIG. 9

shows in a diagram the time course of the individual pressures and the total pressure.

FIG. 10

shows in a diagram the time course of the individual pressures and the total pressure.

FIG. 11

shows in a diagram the time course of the individual pressures and the total pressure.

Ways to carry out the invention

In the Figures 1 and 2 a first possible embodiment of the inventive double diaphragm pump 1 is shown in a three-dimensional view. The double diaphragm pump 1 comprises a housing 9, in which a first diaphragm pump and a second diaphragm pump are accommodated (see FIGS. 3 and 4 ). On the housing 9, an operating unit with two pressure gauges 22, 23, two pressure adjusters 20, 21, a compressed air connection 4 and a stopcock 8 may be arranged. With the control unit can the air pressure for supplying the double diaphragm pump and the delivery pressure of the double diaphragm pump are set and monitored. In addition, the compressed air for the supply of the first and the second diaphragm pump can be connected to the compressed air connection 4. In FIG. 2 is the double diaphragm pump 1 without the control unit shown. At the top of the housing 9 is a compressed air connection 7 which can be connected to the operating unit. On the side of the housing 9 are a pump inlet 2 for the medium to be pumped and a pump outlet 3 for the medium. With the help of the novel double-membrane pump, various liquid materials, such as paints, lacquers, acids, alkalis, stains, solvents, water, turpentine, adhesives, glues, sewage sludge, gasolines, oils, liquid chemicals, liquid media with solids, media with high viscosity, toxic media, liquid pigment dyes, ceramic casting, slip and glazes are promoted.

In FIG. 3 the first embodiment of the novel double membrane pump is shown in longitudinal section from the side along the section AA. FIG. 4 shows the first embodiment of the inventive double membrane pump in longitudinal section from above along the section BB. FIG. 5 shows the inventive double diaphragm pump in cross section along the section CC. As already mentioned, the double diaphragm pump according to the invention comprises two individual diaphragm pumps, which by means of a correspondingly designed control 30 (see FIG FIGS. 6 . 7 and 8th ) can be controlled.

First diaphragm pump

The first diaphragm pump is in the FIGS. 3 and 4 shown on the left. It comprises a membrane 10, which is preferably round and which is attached at its outer end between two walls 18 and 17.1. The membrane 10 forms a flexible partition wall between the walls 18 and 17.1. In this way, the membrane 10 forms together with the wall 18, a first chamber, which is referred to below as a compressed air chamber or in short as a pressure chamber 14. In addition, the membrane 10 forms with the wall 17. 1 a second chamber, which is referred to below as the conveying or pumping chamber 13. The membrane 10 is moved by means of a drive means 15 back and forth. The drive means 15 comprises a cylinder 11 with two cylinder chambers 11.1 and 11.2. The drive means 15 may also include the compressed air chamber 14. In between there is a movably mounted piston 12, which is connected via a piston rod 12.1 with the membrane 10. The piston rod 12.1 may be connected at its one end by means of a screw to the piston 12. Instead, the end of the piston rod 12.1 may also be provided with an external thread and secured with a nut on the piston 12. At its other end, the piston rod 12.1 protrudes through the wall 18 and is connected to the membrane 10, for example by means of a positive connection. For this purpose, the piston rod 12.1 can be encapsulated with the membrane 10. The piston rod 12.1 has a groove 12.2. Together with valve bodies, it forms two valves 35 and 36. These are preferably used as limit switches. But the piston rod 12.1 can also be designed so that with it two valves 35, 36 can be actuated.

The two valves 35 and 36 each have a control input and can each have two switching states A or B. taking. In the idle state, that is, when no signal is applied to the control inputs of the valves 35 and 36, the valves 35 and 36 are in the switching state B (see also FIG. 6 ). If the piston 12 and thus also the piston rod 12.1 on the far left are located, the valve 35 is in the switching state A and the valve 36 is in the switching state B. If the piston 12 and the piston rod 12.1 are far enough to the right, the valve 35 is in the switching state B and the valve 36 in the switching state A.

Second diaphragm pump

In the first embodiment of the novel double diaphragm pump, the second diaphragm pump is constructed mirror-symmetrically to the first diaphragm pump. This is advantageous, but not mandatory.

The second diaphragm pump is in the FIGS. 3 and 4 shown on the right. It comprises a membrane 110, which is preferably round and which is fastened at its outer end between two walls 17.2 and 19. The membrane 110 forms a flexible partition wall between the walls 17.2 and 19. In this way, the membrane 110 together with the wall 19, a first chamber, which is hereinafter referred to as a compressed air chamber or in short as a pressure chamber 114. In addition, the membrane 110 with the wall 17.2 forms a second chamber, which is referred to below as the pump or delivery chamber 113. The membrane 110 is reciprocated by a drive means 115. The drive means 115 comprises a cylinder 111 with two cylinder chambers 111.1 and 111.2. The drive means 115 may also include the compressed air chamber 114. In between there is a movably mounted piston 112 which is connected to the membrane 110 via a piston rod 112.1. The piston rod 112.1 may be connected at its one end by means of a screw to the piston 112. Instead, the end of the piston rod 112.1 can also be provided with an external thread and fixed by means of a nut on the piston 12. At its other end, the piston rod 112.1 protrudes through the wall 18 and is connected to the membrane 110. The piston rod 112.1 has a groove 112.2, which may be formed as an annular groove. Together with the associated valve bodies, it forms two valves 37 and 38. The valves 37 and 38 serve as limit switches.

The two valves 37 and 38 can each occupy two switching states A or B. Are the piston 112 and thus also the piston rod 112.1 far left, the valve 37 is in the switching state A and the valve 38 in the switching state B. If the piston 112 and the piston rod 112.1 far enough right, the valve 37 is in the switching state B and the valve 38 in the switching state A (see also FIGS. 6 . 7 and 8th ).

Basically, there is no mechanical coupling between the first and the second diaphragm pump. In order for the double membrane pump 1 according to the invention to convey the desired amount of material with the desired pressure and the desired pressure profile, the first and second diaphragm pumps are driven by compressed air and controlled accordingly.

An advantage of the double diaphragm pump according to the invention is that the two diaphragms 10 and 110 of the double diaphragm pump 1 can be arranged independently of one another. For example, the membranes 10 and 110 may face each other as shown in the figures (left, right). However, the two membranes 10, 110 can also be arranged one above the other (top and bottom), side by side or even offset from one another.

The pump inlet 2 is connected both to the inlet of the delivery chamber 13 and to the inlet of the delivery chamber 113. In order to ensure that the material to be conveyed does not pass from the delivery chamber back to the inlet 2 during the delivery phase, check valves 5 and 105 are provided.

The outlets 13.3 and 113.3 of the delivery chambers 13 and 113 are connected to each other and open into the pump outlet 3 on the housing 9. In order to prevent the material to be conveyed from the one delivery chamber into the other delivery chamber, check valves 6 and 106 are provided.

In the first embodiment is spatially seen between the two diaphragm pumps, a main valve 32. The main valve 32 may of course also be located in a different location. The main valve 32 has two control inputs 32.1 and 32.2 and two switching states or positions A and B (for the mechanical structure see Figures 3 and 5 and for the functionality see FIGS. 6 . 7 and 8th ). In the present embodiment, it is designed as a differential valve. But this is not absolutely necessary.

Below the main valve 32 is a flip-flop valve 31 with four switching states or positions A, B, C and D (see also Figures 3 and 6 ). The flip-flop valve 31 may also be located at another location. The operation of the flip-flop valve 31 will be explained later.

How the first diaphragm pump, the second diaphragm pump and the valves 31 - 37 can be connected to each other, is from the FIGS. 6 to 8 refer to.

The controller 30 controls the two drive means 15 and 115. Basically, it is configured and operable to control the two drive means 15 and 115 depending on one or more conditions. A condition may be, for example, a certain period of time, reaching a certain position or reaching a certain pressure.

In the following, several embodiments of the controller 30 will be described.

Time-dependent control

The position in which the membrane 10 is located when the double-diaphragm pump 1 is turned off is referred to below as the idle state of the membrane 10. The same applies mutatis mutandis to the membrane 110. Basically, it does not matter in what positions the membranes 10 and 110 are when the double diaphragm pump 1 is turned off. However, the functioning of the Double diaphragm pump 1 to be able to explain better, it is assumed below that the diaphragm 10 is at rest at its left dead center and the diaphragm 110 at its left dead center. The membrane 10 is at its left dead center when it is in its extreme left deflection, which is referred to as the rear end position of the membrane 10. In FIG. 9 is located at time t0, the membrane 10 in the left dead center. The membrane 10 is at its right dead center when it is in its extreme right deflection, which is referred to as the front end position of the membrane 10. The same applies mutatis mutandis to the membrane 110. The diaphragm 110 is thus at its left dead center when it is in its outermost left-hand deflection, which is referred to as the front end position of the diaphragm 110. The diaphragm 110 is at its right dead center when in its outermost right-hand turn, which is referred to as the rear end position of the diaphragm 110. In FIG. 9 is located at time t0, the membrane 110 in the left dead center.

In the following, the operation of the double diaphragm pump 1 with the in the FIGS. 1 to 5 shown construction and in FIG. 6 shown pneumatic circuit diagram using the in FIG. 9 illustrated diagram further explained. The double diaphragm pump 1 starts operating when the pistons 12 and 112 begin to move the two diaphragms 10 and 110. In the present example, the controller 30 ensures that at time t0 = 0 s, the membrane 10 is pressed via the piston 12 into the pumping chamber 13 and in the pumping chamber 13 builds up a pressure p13. The pressure p13 ramps up in the pumping chamber 13 until it has reached the maximum pressure pmax (in the present example about 2.2 bar) at time t1 and then remains constant until time t5 (ie for a duration of about 0.8 s). During this time, the piston 12 pushes the membrane 10 to the right until it has reached its right dead center. From then on, the pressure p13 in the pumping chamber 13 drops rapidly until it has dropped to zero at time t8. The process taking place between the two times t0 and t8 is referred to as the pumping or delivery phase F13 of the left-hand part of the double-diaphragm pump 1. In this phase, the fluid located in the pumping chamber 13 is pushed out of the pumping chamber. The left part of the double diaphragm pump 1 (left diaphragm pump) thus promotes fluid during this time.

Subsequently, the controller 30 ensures that at time t8 = 1.0 s, the membrane 10 is pulled out of the pumping chamber 13 again via the piston 12 and builds up a negative pressure p13 in the pumping chamber 13. The pressure p13 drops in the pumping chamber 13 in a ramp shape until it reaches and remains at time t9 the maximum negative pressure pmin (in the present example about -0.5 bar based on the normal pressure of 1 bar, which is shown in the diagram as a zero line) then until time t10 (ie for a duration of about 0.3 s) constant. During this time, the piston 12 pulls the membrane 10 to the left until it has reached its left dead center at time t10. From this point on no further fluid is sucked into the pumping chamber 13. The check valve 5 in the suction line closes. From then on, the negative pressure in the pumping chamber 13 decreases again, reaches zero again at time t11 and then remains at zero until time t13. The one between the two times t8 and t13 is referred to as suction phase S13. The left part of the double diaphragm pump 1 so sucks during this time fluid. The intake phase S13 is followed by a further delivery phase F13 and a further intake phase S13. Delivery phase F13 and intake phase S13 alternate and together form a cycle.

The controller 30 also ensures that at the time t0 = 0 s, the membrane 110 is pulled out of the pumping chamber 113 via the piston 112 and in the pumping chamber 113 a negative pressure p113 builds up (see FIG. 9 ). The pressure p113 drops in the pumping chamber 113 in a ramp shape until it reaches the maximum negative pressure pmin (in the present example around -0.5 bar) at time t2 and then remains until time t3 (ie for a duration of about 0.3 s ) constant. During this time, the piston 112 pulls the diaphragm 110 to the right until it has reached its right dead center at time t3. From this point on no further fluid is sucked into the pumping chamber 113. The check valve 105 in the suction line closes. From there, the negative pressure in the pumping chamber 113 decreases again, reaches the value zero again at the time t4 and then remains at zero until the time t6. The process taking place between the two times t0 and t6 is referred to as suction phase S113. The right-hand part of the double diaphragm pump 1 (right diaphragm pump) therefore sucks in fluid during this time.

Subsequently, the controller 30 ensures that at time t6 = 0.9 s, the membrane 110 is pushed back into the pumping chamber 113 via the piston 112 and builds up an overpressure p113 in the pumping chamber 113. The pressure p113 ramps up in pumping chamber 113 until at time t7 it reaches the maximum pressure pmax (in the present example about 2.2 bar) and then remains constant until time t12 (ie for a duration of about 0.8 s). During this time, the piston 112 pushes the diaphragm 110 to the left until it reaches its left dead center. From then on, the pressure p113 in the pumping chamber 113 drops rapidly. The process taking place between the two times t6 and t15 is referred to as the pumping or delivery phase F113 of the right-hand part of the double-diaphragm pump 1. In this phase, the fluid located in the pumping chamber 113 is pushed out of the pumping chamber 113. The right part of the double diaphragm pump 1 thus promotes fluid during this time. The delivery phase F113 is followed by a further intake phase S113 and a further delivery phase F113. Ejection phase F113 and suction phase S113 alternate, form a cycle together and return periodically.

With the aid of the controller 30, it is ensured that the delivery phase F13 of the right-hand part of the double-membrane pump is connected to the delivery phase F13 of the left-hand part of the double-membrane pump, and this is again followed by a delivery phase F13 of the left-hand part of the double-membrane pump, etc. the delivery phases F13 and F113 of the left and right part of the double diaphragm pump and produce so after a short start-up phase, a continuous, uninterrupted fluid flow with constant delivery pressure p1.

The controller 30 is formed in the present embodiment so that it outputs compressed air signals at certain times. Basically, but no Compressed air signals, but may also be hydraulic or electrical signals, so any suitable form of commands. Therefore is spoken in following of commands. The condition when a particular command is issued is thus related to the time, and preferably to a certain period of time. For example, it can be provided that the command "Start the delivery phase F113" is output 0.9 s after the suction phase S113 has been started (see FIG FIG. 9 ). Instead, the command "Start the delivery phase F113" could also be issued t6 = 0.8 s after the suction phase S113 was started (refer to FIG FIG. 11 ). However, the command could also be "Build up a pre-pressure pv in the delivery chamber 13" and could be issued 0.35 s after the suction phase S113 has been started (see FIG. 10 ).

In spray technology, the nozzle used in the spray gun usually specifies the speed or frequency with which the pump operates. If the pump is operated with a single spray gun, it operates at a different frequency than when it supplies two spray guns. Thus, different cycle times may result depending on the operating conditions. The working frequency of the double diaphragm pump remains constant when the external operating conditions remain unchanged.

Position or path-dependent control

The controller 30 may also be configured to issue a command or commands when the piston 12 or 112 or the diaphragm 10 or 110 or otherwise movable component has reached a certain position or traveled a certain way. The condition when a particular instruction is issued is thus related to the position of a particular component or to the way a particular component has traveled. For example, it may be provided that the command "Start the delivery phase F113" is output when the piston 12 has reached the position x. In the diagram in FIG. 9, this would correspond to the time t6. Instead, the command "Start the delivery phase F113" could be issued even when the piston 12 has reached the position x-1 (see t6 FIG. 11 ). The command could also be "Build in the delivery chamber 13 a pre-pressure" and issued when the piston 112 has reached the position z. The position z corresponds to the diagram in FIG FIG. 10 the time t3.

Pressure-dependent control

The controller may also be configured to issue a command or commands when the pressure p13 in the pumping chamber 13, the pressure p113 in the pumping chamber 113, or the air pressure in one of the cylinders 11, 111, respectively, has reached a certain threshold. The condition when a particular command is issued is thus related to the pressure at a particular location. For example, it may be provided that the command "Build in the delivery chamber 13 a form pv on" is issued when the negative pressure p113 has decreased in the pumping chamber 113 by one or to a certain value. In the diagram in FIG. 10 this would be one Match time between the times t3 and t4.

Embodiment with pressure ratio 1: 1

At the in FIG. 6 shown embodiment of the inventive double diaphragm pump is a 1: 1 pressure transmission. That is, the pressure acting on the pumping chamber is substantially as great as the pressure acting on the pressure chamber.

The controller 30 includes the flip-flop valve 31 with the four switching states or positions A, B, C and D. The switching states A and D are those switching states that remain even after removal of the control signal. The last taken switching state, ie either A or D, is therefore stored. The switching states B and C of the flip-flop valve 31 are transition positions. Thus, if the control input 31.1 of the flip-flop valve 31 is acted upon by compressed air, the flip-flop valve 31 first changes to the transition position C for a certain period of time, then to the transition position B for a certain period of time, and then finally remains in the position A. By analogy, the same applies to the opposite direction. Thus, when the control input 31.2 of the flip-flop valve 31 is acted upon with compressed air, the flip-flop valve 31 first changes for a certain period of time in the transition position B, then for a certain period of time in the transition position C and then persists in the Position D.

The flip-flop valve 31 is in the position A, as in FIG. 6 are shown, the terminals 1 and 2 with each other connected, so that air can get from port 1 to port 2. In addition, in the position A, the terminals 5 and 7 are connected to each other. If the flip-flop valve 31 is in the position B (not shown in the figures), the terminals 1 and 2 are connected to each other. The terminals 5 and 7 are not connected to each other in position B, however. If the flip-flop valve 31 is in the position C (not shown in the figures), only the terminals 1 and 3 are connected to each other. When the flip-flop valve 31 is in the D position (not shown in the figures), the terminals 1 and 3 are connected to each other. In addition, in the D position, the terminals 4 and 6 are connected to each other. In which of the positions A to D the flip-flop valve 31 is located depends on whether the control port 31.1 or the control port 31.2 is pressurized with compressed air. It may well be that the flip-flop valve 31 is in the position A, B, C or D only for a very short time.

The controller 30 also includes a main valve 32 with two control inputs 32.1 and 32.2 and two switching states or positions A and B. When the control input 32.1 is supplied with compressed air, the valve 32 assumes the switching state A. In the switching state A, the terminals 1 and 3 are connected together. In addition, in the switching state A, the terminals 2 and 4 are connected together. When the control input 32.2 is pressurized with compressed air, the valve 32 assumes the switching state B. In switching state B, the connections 1 and 4 are connected to each other (see also FIG. 5 ). In addition, in the switching state B, the terminals 2 and 3 are connected together.

In addition, a pressure relief valve 33 is provided, which is connected on the one hand to a compressed air source 50 and on the other hand to the main valve 32. The pressure relief valve 33 may also be designed as an adjustable pressure relief valve.

In addition, the controller 30 includes four valves 35, 36, 37 and 38. The valve 35 is coupled to the drive 15 and can assume two switching states A or B. When the diaphragm 10 or the drive piston 12 is in the rear end position, the valve 35 is in the switching state A. In this state, the valve ports are connected to each other. Is the diaphragm 10 and the drive piston 12 in the front end position or, as in the FIG. 6 shown, between the front and the rear end position, the valve 35 is in the switching state B. In this state, the valve ports are not connected to each other. The valve 36 is in the position A when the piston 12 is on the far right, otherwise it is in the switching state B.

The valve 37 may be identical to the valve 35 and is coupled to the drive 115. When the diaphragm 110 or the drive piston 112 is in the front end position, the valve 37 is in the switching state A. In this state, the valve ports are connected to each other. Is the diaphragm 110 or the drive piston 112 in the rear end position, or as in the FIG. 6 shown, between the front and the rear end position, the valve 37 is in the switching state B. In this state, the valve terminals are not connected to each other.

The valve 38 is in the position A when the piston 112 is on the far right, otherwise it is in the switching state B.

When the flip-flop valve 31 is in the position A, the control port 32.2 of the main valve 32 is not pressurized with air, but is connected to the atmosphere. This causes the main valve 32 to be in the switching state A. The reason for this is that the control port 32.1 of the main valve designed as a differential valve is in principle supplied with compressed air. In switching state A, the compressed air coming from the compressed air source 50 compressed air is forced into the compressed air chamber 114 and into the right piston chamber 11.2 of the cylinder 11. The piston 12 is pushed to the left and pulls the membrane 10 also to the left toward the rear end position. The volume in the delivery chamber 13 is increased, the left diaphragm pump is in the intake phase. The pressurized air in the pressurized air chamber 114 causes the diaphragm 110 to be urged leftward toward the forward end position. The volume in the delivery chamber 113 is reduced, the right diaphragm pump is in the delivery phase. During this phase, the terminal 3 of the flip-flop valve 31 is closed, so that the compressed air is not forwarded from there. Also in the valves 35 and 37, the connections are closed, so that the compressed air is not forwarded from there instantly. Because the terminal 5 of the flip-flop valve 31 is connected to the terminal 7 open to the atmosphere, any pilot air applied to the control terminal 31.2 may be sent to the outside of the atmosphere. The control connection 31.2 is relieved and is thus pressure-free. The connection 4 of the flip-flop valve 31 is closed, as is the connection of the valve 35. As a result, the compressed air applied to the control port 31.1 compressed air can not escape, the air pressure at the control port 31.1 is maintained.

While the piston rod 112.1 moves to the left, the valve 37 remains closed for the time being. When the piston rod 112.1 has then moved far enough to the left, the valve 37 is opened by the groove 112.2 on the piston rod 112.1 and is in the state A.

While the piston rod 12.1 moves to the left, the valve 35 remains closed for the time being. Only when the piston rod 12.1 has moved far enough to the left, the valve 35 is opened by the groove 12.2 on the piston rod 12.1 and changes to the state A. As soon as the two valves 37 and 35 have changed to the state A, the compressed air from the compressed air source 50 via the valve 37 and the valve 35 to the control input 31.1 of the flip-flop valve 31 passed.

The flip-flop valve 31 changes for a certain time in the position B. The control port 32.2 of the main valve 32 remains pressure-free, because it is not supplied via the flip-flop valve 31 with compressed air. This leaves the main valve 32 in the previous position. The terminals 3 and 4 of the flip-flop valve 31 remain closed. The connection 5 of the flip-flop valve 31, however, is now closed. This has the effect that the control air at the control connection 31.2 can no longer escape into the atmosphere.

The flip-flop valve 31 changes after a certain time from the position B to the position C. The control terminal 32.2 of the main valve 32 is now pressurized with compressed air. The main valve 32 changes from the position A to the position B. This causes the compressed air in the left piston chamber 111.1 of the cylinder 111 and enters the compressed air chamber 14. As a result, the piston 112 is pushed to the right, which in turn pulls the membrane 110 to the right in the direction of the rear end position. The right diaphragm pump is now in the intake phase. The pressure in the compressed air chamber 14 causes the membrane 10 is pushed to the right towards the front end position. The left diaphragm pump is now in the delivery phase.

The flip-flop valve 31 changes to the switching state D. While the piston rod 112.1 moves to the right, the valve 37 is closed, the valve 38 remains closed for the time being. When the piston rod 112.1 has moved far enough to the right, the valve 38 is brought from position B to the position A by the annular groove 112.2 on the piston rod 112.1.

While the piston rod 12.1 moves to the right, the valve 35 is closed, the valve 36 remains initially closed, but is connected on the output side via the flip-flop valve 31 to the control input 32.2 of the main valve 32. Only when the piston rod 12.1 has moved far enough to the right, the valve 36 is brought by the annular groove 12.2 on the piston rod 12.1 from state B to state A. As a result, compressed air from the compressed air source 50 via the valve 36 and the valve 38 to the control input 31.2 of the flip-flop valve 31. The flip-flop valve 31 changes back from the state D back and that for a short time in the state C. and then in the state B and finally remains in the state A. During this time, the sequence is repeated in the opposite direction, this time the left diaphragm pump delivers and sucks the right diaphragm pump.

Embodiment with pressure ratio> 1: 1

At the in FIG. 7 shown embodiment of the inventive double diaphragm pump is a pressure ratio> 1: 1. That is, the pressure acting on the pumping chamber is greater than the pressure acting on the pressure chamber.

In contrast to the version 1: 1 according to FIG. 6 the cylinder chamber 11.1 is not connected to the atmosphere, but is acted upon at certain times for a certain period of time with compressed air. This ensures that the pressure acting on the pumping chamber 13 is greater than the pressure acting on the pressure chamber 14. The cylinder chamber 111.2 is not connected to the atmosphere, but is acted upon at certain times for a certain period of time with compressed air. As a result, higher delivery pressures can be achieved, which are for certain media, eg media with higher viscosity, an advantage. Higher discharge pressures may also be beneficial for bridging longer distances.

Thus, the cylinder chambers 11.1 and 111.2 can be acted upon with compressed air, it makes sense to seal this accordingly. The in the FIGS. 3 and 4 shown embodiment of the cylinder chambers would therefore still to supplement seals. As seals O-rings can be used, which are placed between the cylinder wall and the housing 9.

Further embodiment with pressure ratio> 1: 1

At the in FIG. 8 shown embodiment of the inventive double diaphragm pump is as in the embodiment according to FIG. 7 a version with a pressure ratio> 1: 1.

As in the first and the second embodiment, in the third embodiment in the controller 30 Although a flip-flop valve is used, but this has only two switching states A and B. In the idle state, that is, when no control signals to the control inputs 39.1 and 39.2 of the flip-flop valve 39, it is in the switching state A.

At the beginning, therefore, the main valve 32 is in the state A and directs the compressed air coming from the compressed air source 50 into the cylinder chamber 11.2, the pressure chamber 114 and into the cylinder chamber 111.2. As a result, the piston 12 is pressed to the left. This pulls on the piston rod 12.1, the membrane 10 also to the left, so that in the pumping chamber 13, a negative pressure. The left diaphragm pump is now in the suction phase. Also, the piston 112 is pushed to the left. This presses on the piston rod 112.1, the membrane 110 also to the left, so that in the pumping chamber 13, an overpressure arises. This is supported by the with Compressed air pressure chamber 114. The right diaphragm pump is now in the pumping phase.

Once the piston 12 has reached the left end position, the valve 35 is brought from state B to state A through the groove 12.2 in the piston rod 12.1. When the piston 112 has also reached the left end position, the valve 37 is also brought from the state B into the state A through the groove 112. 2 in the piston rod 112. 1. As a result, compressed air flows to the control input 39.1 of the flip-flop valve 39 and causes it to change from the state A to the state B. The flip-flop valve 39 now directs the compressed air to the control input 32.2 of the main valve 32, so that this also changes from the state A to the state B. Now the compressed air passes through the main valve 32 from the compressed air source 50 into the cylinder chamber 11.1, the pressure chamber 14 and into the cylinder chamber 111.1. As a result, the piston 12 is pushed to the right. This presses on the piston rod 12.1, the diaphragm 10 also to the right, so that in the pumping chamber 13, an overpressure is created. The left diaphragm pump is now in the pumping phase. This is supported by the pressure chamber 14 pressurized with compressed air. The piston 112 is also pressed to the right. This pulls on the piston rod 112.1, the membrane 110 also to the right, so that in the pumping chamber 13, a negative pressure. The right diaphragm pump is now in the suction phase. The two control inputs 39.1 and 39.2 of the flip-flop valve 39 are also connected via a respective throttle 40 or 41 to the atmosphere, so that the control inputs 39.1 and 39.2 can be vented when no control command comes from the valves 35 and 38.

Combined control

Of course, the above-mentioned embodiments of the controller can also be combined with each other. Thus, the condition for triggering a particular command may be related to time while the condition for triggering another command is related to the position of a particular device. In addition, the condition for triggering another command may be related to the pressure at a particular location. The condition triggering a command can be any physical property, such as time, location, pressure, etc. Any number of conditions can be linked together. For example, a command can not be triggered until two conditions have been met (AND operation). A command can also be triggered if one of two conditions is met (OR operation). It is also possible for a command to be issued permanently and until another command is present for the command to be withdrawn.

With the limit switch 35 at the drive means 15 and the limit switch 37 when the drive means 115 can be ensured that both drive means 15 and 115 drove the full stroke.

Isochronous control of the first and the second diaphragm pump is advantageous, but not absolutely necessary. Isochronous means here that the signals are in a constant phase relation to each other. For example, the control signals generated by the valves 35 and 37 be isochronous to each other. In addition, the control signals generated by the valves 36 and 38 may be isochronous to each other. Their phase shift is preferably between 170 ° and 190 °. The pressure curves p1 and p2 can also be isochronous. Both pressure curves p1 and p2 have the same characteristics and the same cycle time, but are more or less shifted in time relative to each other. Their phase shift is also preferably between 170 ° and 190 °.

The foregoing description of the embodiments according to the present invention is for illustrative purposes only. Various changes and modifications are possible within the scope of the invention. Thus, for example, the first and the second diaphragm pump according FIGS. 1 to 5 both with the controller according to FIG. 6 as well as with the control according to FIG. 7 or 8th operate. The components shown can also be combined with one another in a different way than shown in the figures.

Instead of the air-operated drive means 15, 115 shown in the figures, it is also possible to use drive means in which the piston 12 can be moved 112 in at least one direction with a resilient element. A combination of compressed air and spring drive is conceivable.

Instead of the pistons 12, 112 shown in the figures, the cylinders 11 and 111 may each also have a membrane. The membrane may also be in the form of a rolling membrane. These arranged in the cylinders membranes can be moved with compressed air and / or with a resilient element become. The resilient element may for example be a compression spring.

A rolling diaphragm is a flexible seal that allows a relatively long piston stroke. It often has the shape of a truncated cone or a cylinder and is rotated in itself. The rolling diaphragm can be clamped circumferentially. During the stroke, it rolls alternately on the piston and on the cylinder wall. The rolling motion is smooth and frictionless. There is no sliding friction, no breakaway friction and no pressure loss.

If the pistons 12 and 112 or the diaphragms arranged in the cylinders are to be moved by way of a compression spring, this is preferably done in the suction phase of the respective diaphragm pump. The compression springs are then advantageously in the cylinder chambers 11.2 and 111.2.

In the double diaphragm pump 1 it can be provided that the drive means 15 and 115 each have at least one sensor. The sensor is used to detect the position of the drive piston 12 or the piston rod 12.1 or the drive piston 112 or the piston rod 112.1.

As a sensor, for example, serve a limit switch. With the limit switch, the end position (dead center) of the drive means 15 can be detected. The drive means 15 can also have a limit switch for detecting the left end position and a further limit switch for detecting the right end position (not shown in the figures). The same can be done for that Drive means 115 apply. In the FIGS. 5 to 8 the limit switches are designed as valves 35 to 38. They may instead be electrical or mechanical switches. The controller is then adapted to these switches.

If the drive cylinders 11 and 111 are twice as large as the diaphragms 10 or 110 or even larger, a pressure transmission ratio of, for example, 3: 1 can also be achieved. This means that 6 bar air pressure then corresponds to 18 bar fluid pressure.

During operation, the membranes 10 and 110 are reciprocated. It can happen that the membranes fold over, but this is usually undesirable because this process can damage the membrane. In order to reduce the risk that the diaphragms 10 and 110 fold over and thereby become damaged over time, the following structure may be provided. The pressure chamber 14 in the membrane 10 and the pressure chamber 114 in the membrane 110 are not connected to the main valve 32, but with a vacuum generator. This creates such a strong vacuum in the two pressure chambers 14 and 114 that the membranes 10 and 110 do not fold over, but essentially retain their shape.

The membranes 10 and 110 may be mechanically biased before the delivery phase. As a result, the membrane generates a certain pressure in the delivery chamber right at the beginning of the delivery phase, and for approximately as long as, inter alia, the air pressure in the pressure chamber has built up. This can be used to compensate for the inertia of the system and fine-tune it. The membranes should not be too tightly biased, as this may otherwise lead to a sawtooth pressure curve.

LIST OF REFERENCE NUMBERS

1

Double diaphragm pump

2

pump inlet

3

pump outlet

4

Compressed air connection

5

check valve

6

check valve

7

Compressed air connection

8th

stopcock

9

casing

10

membrane

11

cylinder

11.1

left piston chamber

11.2

right piston chamber

12

piston

12.1

piston rod

12.2

Ring groove in the piston rod

13

Pump or delivery chamber

13.3

Pumpkammerauslass

14

pressure chamber

15

drive means

17.1

wall

17.2

wall

18

wall

19

wall

20

Pressure regulator

21

Pressure regulator

22

manometer

23

manometer

30

control

31

Flip-flop valve

31.1

control connection

31.2

control connection

32

main valve

32.1

control connection

32.2

control connection

33

Pressure relief valve

35

Valve

36

Valve

37

Valve

38

Valve

39

Flip-flop valve

39.1

control connection

39.2

control connection

40

throttle

41

throttle

50

Compressed air source

105

check valve

106

check valve

110

membrane

111

cylinder

111.1

left piston chamber

111.2

right piston chamber

112

piston

112.1

piston rod

112.2

Ring groove in the piston rod

113

Pump or delivery chamber

113.3

Pumpkammerauslass

114

pressure chamber

115

drive means

p1

Pressure at the outlet of the double diaphragm pump 1

p13

Pressure in the pumping chamber 13

p113

Pressure in the pumping chamber 113

pv

form

Claims (17)

1. A double membrane pump,

   - wherein a first membrane (10) is provided forming a wall of a first pump chamber (13),

   - wherein the first membrane (10) is movable by means of a first mechanical drive means (15),

   - wherein a second membrane (110) is provided forming a wall of a second pump chamber (113),

   - wherein the second membrane (110) is movable by means of a second mechanical drive means (115) that is independent from the first drive means (15),

   - wherein a control system (30) for the drive means (15, 115) is provided that is configured and operable such that it controls the two drive means (15, 115) in dependence of one or more conditions.
2. The double membrane pump according to claim 1, wherein said condition is referred to the time, the pressure, the travel and/or the position.
3. The double membrane pump according to claim 1 or 2, wherein the control system (30) is configured and operable such that it already provides, even before the membrane (10; 110) has reached its dead center in the one pump chamber (13; 113), for a generation of pressure in the other pump chamber (113; 13).
4. The double membrane pump according to claim 1 or 2, wherein the control system (30) is configured and operable such that it provides, when the underpressure (p13; p113) in the one pump chamber (13; 113) drops below a certain threshold value, for a generation of pressure in this pump chamber (113; 13).
5. The double membrane pump according to claim 1 or 2, wherein the control system (30) is configured and operable such that it controls the two drive means (15, 115) in a manner shifted in time relative to each other, so that the two membranes (12, 112) move in a manner shifted in time relative to each other.
6. The double membrane pump according to claim 1 or 2, wherein the control system (30) is configured and operable such that it controls the two drive means (15, 115) isochronously relative to each other.
7. The double membrane pump according to one of claims 1 to 6,

   - wherein a first pressure chamber (14) is provided that is separated by the first membrane (10) from the first pump chamber (13),

   - wherein a second pressure chamber (114) is provided that is separated by the second membrane (110) from the second pump chamber (113).
8. The double membrane pump according to one of claims 1 to 7,
   wherein at least one of the drive means (15, 115) is a drive means being operable with pressurized air.
9. The double membrane pump according to one of claims 1 to 8,
   wherein the drive means (15, 115) each include a piston (12, 112) being movable in a cylinder (11, 111) or a membrane being movable with pressurized air.
10. The double membrane pump according to one of claims 1 to 8,
    wherein the drive means (15, 115) each include a piston (12, 112) being movable in a cylinder (11, 111) or a membrane being movable with a resilient element at least in one direction.
11. The double membrane pump according to one of claims 1 to 10,
    wherein the drive means (15, 115) each include at least one sensor for detecting the end position.
12. The double membrane pump according to claim 11,
    wherein the control system (30) is configured and operable such that it controls the two drive means (15, 115) in dependence of the signal coming from the sensor (35 - 38).
13. The double membrane pump according to claim 11 or 12, wherein the control system (30) is configured and operable such that it causes a reversal in direction of the drive means (15, 115), when the sensor (35) is actuated by the first drive means (15) and the sensor (37) is actuated by the second drive means (115).
14. The double membrane pump according to one of claims 1 to 13,

    - wherein the first and second pump chambers (13, 113) each include a pump chamber outlet (13.3, 113.3), and

    - wherein the pump chamber outlets terminate in a common pump outlet (3).
15. The double membrane pump according to one of claims 1 to 14,

    - wherein the control system (30) includes a differential valve (32),

    - wherein the differential valve (32), in the one position (A), connects a source of pressurized air (50) to the first drive means (15) such that it moves the first membrane (10) such that an underpressure is generated in the first pump chamber (13),

    - wherein the differential valve (32), in the other position (B), connects the source of pressurized air (50) to the second drive means (115) such that it moves the second membrane (110) such that an underpressure is generated in the second pump chamber (113).
16. The double membrane pump according to claim 15,

    - wherein the differential valve (32), in the one position (A), connects the source of pressurized air (50) to the second drive means (115) such that it moves the second membrane (110) such that an overpressure is generated in the second pump chamber (113),

    - wherein the differential valve (32), in the other position (B), connects the source of pressurized air (50) to the first drive means (15) such that it moves the first membrane (10) such that an overpressure is generated in the first pump chamber (13).
17. The double membrane pump according to claim 15 or 16, wherein the control system (30) includes a flip-flop valve (31) that is controllable by means of end position switches (35, 36, 37, 38), and that controls the differential valve (32).

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