DE19511677C2 - Diaphragm piston pump - Google Patents

Description

The invention relates to a diaphragm piston pump.

Diaphragm pumps are used to pump mechanically abrasive and chemical aggressive media (e.g. suspensions and acids). With these pumps a Displacement effect by moving a membrane clamped in a housing generated. The membrane material can be adapted to the medium.

The membrane can be a hydraulic, pneumatic or mechanical drive exhibit. With a hydraulic diaphragm pump, the displacement effect a piston with the help of an auxiliary liquid (water, oil) on one side of the Membrane transferred. These hydraulic diaphragm piston pumps have one  relatively good efficiency. Your membrane is as a disc or Flat membrane or as a spherical membrane in the form of a cylindrical tube executed. The membrane movement is with a curvature inwards or outwards connected and limited by the elastic stretchability of the membrane. The Throughput requirements for hydraulic diaphragm piston pumps must be met appropriate dimensioning of the membrane can be met. Here enable spherical membranes of smaller sizes. Yet another appears Reduction of the pump sizes is desirable.

For a defined vibration path of the membranes, rigid Support devices may be provided. In the case of flat membranes, at least the A dome-shaped support surface can be arranged on the drive side. On the other The membrane side is only a support surface because of the required permeability suitable fluids possible. With the spherical membrane, the support device the shape of an arched support cylinder. These supports increase the constructive effort, are only partially functional and can the membrane additionally claim. This is especially true when the amount of auxiliary liquid is on the drive side of the pump fluctuates.

To compensate for leaks and to maintain a certain amount Auxiliary liquid have diaphragm piston pumps compensation systems, which the Connect the hydraulic system to an expansion tank. On the hydraulic side of the  Membrane is arranged a button that the during the suction stroke of the piston Detects diaphragm movement and controls an expansion valve to the expansion tank. Excess liquid can be in the pressure stroke of the piston via a throttle body Storage containers are drained. This automatic is also called "Membrane control" called. The piston drive as well as the Membrane control systems are particularly sensitive and can be destroyed Membrane can be easily damaged by the penetrating medium. Therefore these systems are often equipped with monitoring devices, which monitor the condition of the membrane or auxiliary fluid.

With pneumatically driven diaphragm pumps, the displacement effect of the Membrane generated by compressed air. You can use a pneumatic piston have, which acts on a piston rod on the membrane. It can be is a preformed membrane that gives you no stretch in its Clamping level back and forth area has. This membrane has one relatively large displacement volume, which means that the construction volume is low Pump can be reached. However, the displacer volume is due to the rigid Attack of the piston rod reduced. In addition, the piston rod attack can Strengthen the preformed membrane, the material anyway through the constant turning processes in opposite directions are special Subject to stress. Moreover, the efficiency is pneumatic driven diaphragm pumps relatively low.  

But there are also diaphragm pumps with a preformed diaphragm and mechanical drive became known. These pumps have a good one Efficiency. As a result of mechanical attack on the membrane, however here, too, an impairment of the displacer volume and the strength of the Given membrane. In addition, the complex mechanical drive is special at risk of wear, so that destruction of the membrane has considerable cost consequences may have.

DE 76 22 332 U1 describes a device for pressure-dependent delivery quantities. Regulation on piston diaphragm pumps for foreign matter-containing operating fluids known. The diaphragms of the piston diaphragm pumps are between two Stops movable back and forth, on the one hand from an inner surface of the Membrane housing and the other are formed by a support plate. From the DE 43 27 969 A1, a hydraulically driven diaphragm pump is known which is a has at least two individual layers of existing membrane. In the middle of the Membrane is a membrane that is held in contact with the membrane Membrane moving, stiffening element provided. This can be as Support plate be formed and in the end positions of the membrane on a calotte one Attach the pump cover or an end face of a pump body. The Impact of the membrane or the stiffening element at the end stops  act to increase wear. In addition, the dimensionally stable stiffening element limits the displacement volume of the membrane.

Diaphragm pumps are usually used as double-acting or for smaller ones Flow rates also designed as single-acting diaphragm pumps. At double-acting pumps alternately perform a suction stroke on the two diaphragms and a pressure stroke, whereby a in the common pressure line even flow rate is reached. To further even out the Delivery flow can be arranged on the pressure line, an expansion tank. The The expansion tank also has a clamped membrane, one with a gas preloaded primary space from a secondary space loaded with material to be conveyed separates. Even with expansion tanks, the low mobility of Disc membranes disadvantageous. The usability of preformed membranes is impaired by their easy destructibility.

Based on this, the invention is based on the object Diaphragm piston pump to create the larger with a smaller size Flow rates are reached and less risk of destruction.

The task is carried out by a diaphragm piston pump with the characteristics of Claim 1 solved. Advantageous embodiments are in the subclaims contain.  

According to the invention, a hydraulic diaphragm piston pump with a preformed membrane combined. The membrane is free to move Preforming, which is arranged within the edge clamping, from the Auxiliary liquid can be driven. The hydraulic drive ensures a high Efficiency. The preforming of the membrane ensures considerable Deformability and a large displacement. Compared to the previously known The displacement volume will still be used for preformed membranes increased because the rigid attack of a mechanic is eliminated. In addition, the uniform loading of the membrane with auxiliary liquid favorably on their Impact stress and service life. So that the advantages of hydraulic drive, in particular its relatively high efficiency relatively simple and reliable design, with the advantages of a preformed membrane, especially large displacement and thus small Construction, combined. A corresponding membrane preferably comes in one Expansion tank for use, which is used to even out the flow rate connected to the outlet of the pump. This will make it more operational Safety achieved small sizes of the expansion tank. This affects again positive on the design of an aggregate, the diaphragm piston pump and expansion tank combined.  

The preforming of the membrane preferably has a calotte or a double S. On the outer edge of the calotte or the double S, the preforming can be one Have a connection area to a flat edge for clamping the membrane. The connection area is opposite to the calotte or the double S curved and preferably has a much smaller radius of curvature than the calotte on.

The preformed membrane is designed with a special fabric layer so that it withstands the stresses for a long time. The fabric layer prevents over considerable Operating times that the preformed membrane is destroyed due to high flexing work, the separation between primary chamber and secondary chamber is abolished and Product penetrates into the hydraulic area of the pump. Furthermore, by the Fabric layer are ensured that the membrane reaches defined end positions and does not tear in these despite considerable stress. For a reduction in The membrane is stress and reaching defined end positions deformable without stretching. The fabric layer is dimensioned so that it can move the membrane at the operational pressures in the primary and Secondary chamber limited to an area between two end positions. The Tissue membrane then does not require any support devices, which is expensive have limited functionality and impair functionality. The mem  However, bran can also be deformed so that it does not End positions reached. Then the material stress is ge wrestler and the life of the membrane longer. In particular in this mode of operation comes the use of a mem bran without fabric layer into consideration.

An impermeable layer can be on both sides of a fabric layer sige membrane system be arranged so that the fabric layer protected and the membrane is smooth everywhere. you Material can meet the strength and flexibility requirements selected accordingly. It can, for example wise around a fabric layer of polyester or polyamide deln. At least one other membrane system can be made from one Elastomer consist, in particular of a natural or Synthetic rubber (neoprene, Perbunan, etc.). Generally come for the further membrane system soft elastic plastics in Consider e.g. B. the particularly resistant materials Viton or Teflon.

To protect the membrane from excessive differential pressures primary chamber and secondary chamber can be combined with one Safety valve can be connected and facilities to determine the differential pressure when the permissible differential pressure an opening of the safety valve tils effect. This will reduce the risk of a membrane  damage reduced even further. An additional mem industry surveillance in a conventional manner is likely to develop in the Rule because of the considerable operational reliability of the mem No need for a piston piston pump.

The diaphragm piston pump according to the invention is also suitable for setting the amount of auxiliary liquid using Mem control system. For this purpose, the primary chamber can have a Valve device and a throttle body with a template container with auxiliary liquid in the pri märkammer be a button that the membrane on the way to their end position during the suction stroke of the piston Tigt, wherein a control device, the valve device when pressing the button and fluid deficit in the Primary chamber opens.

Further details and advantages of the invention emerge derive from the following description of the associated Drawings of a preferred embodiment. In the Drawings show:

Figure 1 shows a double diaphragm piston pump in section.

Fig. 2 membrane of the same pump in plan view;

Figure 3 shows the same membrane in an enlarged section.

Figure 4 shows another diaphragm for use in the same pump in plan view.

Figure 5 shows the same membrane in an enlarged section.

Fig. 6 expansion tank for the pump of Figure 1 in section.

Fig. 7 shows the same expansion tank in plan view.

The double diaphragm piston pump according to FIG. 1 has a piston 1 in a cylinder 2 . The piston 1 is double-acting, so that piston working spaces 3 , 4 are arranged on its two sides. The piston 1 is connected via a piston rod 5 to a piston drive 6 which moves the piston 1 back and forth in the cylinder 2 .

The pump has a symmetrical housing 7 , in which primary chambers 8 , 9 are arranged. The primary chamber 8 is connected to the piston working space 3 and the primary chamber 9 is connected to the piston working space 4 . Both primary chambers 8 , 9 are bounded by an edge clamped in the housing 7 Mem bran 10 , 11 . The structure of the membranes 10 , 11 is explained below.

The primary chambers 8 , 9 and the piston working spaces 3 , 4 and the connections between them are filled with a liquid, for example with water.

The membranes 10 , 11, on the other hand, each limit a secondary chamber 12 , 13 in the housing 7 for a medium to be conveyed. The secondary chambers 12 , 13 are designed as flow channels, the membranes 10 , 11 forming a side wall section. At the two ends of each secondary chamber 12 , 13 , a ball check valve 14 , 15 , 16 , 17 is formed. In all ball check valves, he opens by moving the ball in the direction of conveyance F upwards.

The ball check valves 14 , 16 are fed from a common suction line 18 and the Kugelrückschlagven tile 15 , 17 open into a common pressure line 19th

The primary chambers 8 , 9 each have a membrane control system. These are of known construction each with a in the direction of the diaphragm 10, 11 spring-spun th button 20, provided 21st A valve device 22 , 23 is assigned to each button 20 , 21 . If a button 20 , 21 is pressed in against its spring preload, it in turn presses a valve plate 24 , 25 of the associated valve device 22 , 23 upwards. In addition, a spring-preloaded ball 26 , 27 is provided between each valve plate 24 , 25 and an upper opening of the valve device 22 , 23 . At the top, each valve device 22 , 23 opens into a storage container 28 with auxiliary liquid.

Finally, each primary chamber 8 , 9 is connected via a throttle plug 29 , 30 to the storage container 28 .

This double acting diaphragm piston pump works like follows:

Due to the reciprocating movement of the piston 1 , the piston working spaces 3 , 4 are alternately reduced or enlarged. The auxiliary liquid is pressed out of the ver decreasing piston working space 3 , 4 into the connected primary chamber 8 , 9 and from the other primary chamber 9 , 8 into the enlarging piston working space 4 , 3 . This creates an overpressure in one primary chamber 8 , 9 , which bulges the associated membrane 10 , 11, and a negative pressure in the other primary chamber 9 , 8 , which bulges the assigned membrane 11 , 10 inwards. Referring to FIG. 1, the piston working space 4 has its minimum volume and the diaphragm 11 is maximum bulged. At the same time, the piston working space 3 has its maximum volume and the membrane 10 is arched to the maximum.

Driven by the piston 1 , the diaphragms 10 , 11 are curved in opposite directions, in opposite directions, inwards and outwards. The arching of a membrane 10 , 11 causes in the adjacent secondary space 12 , 13 a negative pressure, which causes the suction-side ball check valves 15 , 16 and the suction of the medium through the suction line 18 . A bulging of a membrane 11 , 10 , on the other hand, causes a closing of the ball check valves 16 , 14 and simultaneous opening of the ball check valves 17 , 16 with the discharge of pumped medium into the pressure line 19 . Referring to FIG. 1 pumped medium is sucked from the suction line 18 into the secondary chamber 12 and ejected from the secondary chamber 13 out into the pressure line 19. In constant change, the secondary chambers 12 , 13 suck fluid from the suction line 18 and expel it into the pressure line 19 . In this way, a relatively uniform flow rate is achieved.

The diaphragm control system should ensure a constant amount of auxiliary liquid in the drive system. If a membrane 10 , 11 bulges due to a suction stroke of the piston 1 with respect to the associated piston working space 3 , 4 , it lies against the buttons 20 , 21 even before the piston reaches its rear dead center. The piston 1 continues its movement until it reaches its rear dead center. In the event of a liquid deficit, a negative pressure then arises in the primary chamber 8 , 9 . The membrane 10 , 11 pushes the valve plate 24 , 25 up via the buttons 20 , 21 and the pressure difference between the reservoir 28 and the primary chamber pushes the check ball 26 , 27 downward. Hydraulic fluid can then flow from the reservoir 28 through the valve device 22 , 23 into the primary chamber 8 , 9 and compensate for the fluid deficit.

During a pressure stroke of the piston 1 with respect to the piston working chamber 4 , 3 considered, hydraulic fluid is introduced into the reservoir 28 through the throttle 30 , 29 of the connected primary chamber 9 , 8 . At the same time the Ven tilteller 25 , 24 is raised due to the liquid pressure in the primary chamber 9 , 8 . However, the return ball 27 , 26 is closed, so that no hydraulic fluid flows back from the reservoir 28 into the primary chamber 9 , 8 .

Thus, with each suction or pressure stroke, the lack of hydraulic fluid from the storage container 28 is replenished or excess hydraulic fluid is returned to the latter.

According to Fig. 2 and 3 have the preformed membranes 10, 11 each have an edge portion 31 in the form of a flat disc which is provided with holes 32 for flange mounting. The edge region 31 merges into a curved connection region 33 , to which an oppositely curved spherical cap 34 adjoins.

The membrane 10 , 11 has a three-layer structure. This is because it has an inner layer 35 and an outer layer 36 , each made of neoprene, and between them a fabric layer 37 made of polyester. The multilayer structure in the form shown is vulcanized in a mold and thus preformed.

In operation, the pump seen in FIG. 2 and 3 preforming of the diaphragm 10, 11 constantly moving from connecting portion 33 and cap 34 through the plane of the edge region 31 and hergestülpt. Especially in the connection area 33 , which is particularly stressed by membrane deformation, the composite construction causes a considerable increase in strength.

The flat disc-shaped edge region 31 of the membrane 10 , 11 has an average diameter of 295 mm and an outer diameter of 330 mm in the exemplary embodiment. The radius of curvature of the connection area is 12.7 mm compared to a radius of curvature of the spherical cap of 128 mm. The ratios of these radii are thus about 1:10. In the example, the dome has an inside diameter of 235 mm. This inner diameter and the radius of curvature are decisive for the displacement volume. A flat membrane with a corresponding displacement would have a diameter of about 425 mm and would lead to a considerably larger pump.

FIGS. 4 and 5 show another preformed membrane brankolbenpumpe instead of the above-described in the same Doppelmem used and therefore the reference numerals with ', 11' is in the 10th This membrane also has an edge region 31 'in the form of a flat disk, which is provided with holes 32 ' for a flange fastening. The edge region 31 'merges internally into a curved connection region 33 ', which, however, has a considerably larger radius of curvature than the membrane of FIGS. 2 and 3. Between the connection areas 33 ', the membrane 10 ', 11 'has a central area 34 ' which - in diagonal sections according to FIG. 5 - has a double S shape. The central region 34 'has a central Krüm mung area 34 "and encircles opposite domed outer region of curvature these 34', the 'smooth in the connection region 33' passes over. The Krüm mung radii of the regions 34 ', 34' '' agree with the of the connection area 33 '.

The membrane 10 ', 11 ' also has a three-layer structure. This is because it has an inner layer 35 'and an outer layer 36 ' and a fabric layer 37 'in between. For the fabric layers of the membranes, materials are particularly considered that combine enormous strength with low elongation. The multilayer structure in the form shown is vulcanized in a mold and thus preformed.

When operating in a pump according to FIG. 1, the preforming of the membrane 10 ', 11 ' shown in FIGS . 4 and 5 from the connecting section 33 'and the central section 34 ' is constantly moved back and forth with respect to the edge area 31 '. When the diaphragm moves upward (in FIG. 5), essentially only the central curvature region 24 "is arched upwards against its curvature. When it moves downwards (in FIG. 5), the central curvature region 34 " in essentially becomes arched in the opposite direction and the outer region of curvature 34 '''is arched downward against its curvature. The strain on the membrane can be reduced by deformation only in a part of its large deformation range. In addition, the stress caused by the double-S preforming is distributed more evenly across the membrane than with the calotte tenform. In particular, the connection area 33 'is subject to less stress because it has a considerably reduced curvature. The increase in strength due to the composite construction is exploited very well by the double-S preforming. The considerable deformability of this double-S membrane with reduced stress favors the fact that it deviates from FIGS. 4 and 5 in a single layer.

The flat disc-shaped edge region 31 'of the membrane 10 ', 11 'has an average diameter of 295 mm and an outer diameter of 327 mm in the embodiment. The radius of curvature of the connection area is 48 mm. The same radius of curvature is present in the central area 34 "and in the edge area 34 "". In the example, the flat disk-shaped edge area 31 " has an inner diameter of 250 mm. The diameter of the outer area 34 "" - measured between the locations of its maximum Bulge - is 142.5 mm. The central curvature region 34 "protrudes (downwards) by approximately 15 mm from the underside of the edge region 31 'and the outer curvature region 34 ''' projects by approximately 21.5 mm in the opposite direction over the bottom. The displacement volume is defined by the dimensions of the central region 34 'and is considerably larger than the displacement volume of a flat membrane with the same diameter.

FIGS. 6 and 7 show the use of the diaphragm 10, 11 accelerator as Fig. 2 and 3 in a compensation container 38. This has a housing 39 in which the membrane 10 , 11 separates a primary chamber 40 from a secondary chamber 41 .

Two pressure pipes 42 , 43 open into the secondary chamber 41 and can be connected to the outputs of the ball check valves 15 , 17 of the pump of FIG. 1. The outputs of the pumps of FIG. 1 are therefore brought together in the primary chamber 40 . The common pressure line 19 is led out of the housing 39 since Lich.

The primary chamber 40 is closed by a dome-like cover 44 which has a connecting piece 45 for compressed air. A constant compressed air source is coupled there, the pressure of which exceeds the delivery pressure of the pump.

Pressure fluctuations in the outlet of the pump are communicated and damped to the compressed air reservoir 41 via the membrane 10 , 11 . Due to the preformed membrane, the expansion tank manages with a relatively small primary volume 40 . The fabric insert of the membrane 10 , 11 promotes high wear resistance.

Claims (9)

1. Diaphragm piston pump, single- or double-acting in one, two or three cylinder design with a movable diaphragm ( 10 , 11 ) clamped on the edge in a housing ( 7 ) which forms a primary chamber ( 8 , 9 ) of a secondary chamber ( 12 , 13 ) separates a piston ( 1 ) in a cylinder ( 2 ), a piston drive ( 6 ) for a reciprocating movement of the piston in the cylinder while changing a piston working space ( 3 , 4 ), the primary chamber ( 8 , 9 ) and the piston working chamber ( 3 , 4 ) have a connection and are filled with an auxiliary liquid, a suction valve ( 14 , 16 ) between the secondary chamber ( 12 , 13 ) and a suction line ( 18 ) and a pressure valve ( 15 , 17 ) between the secondary chamber ( 12 , 13 ) and a pressure line ( 19 ), the membrane ( 10 , 11 ) having a freely movable preform ( 33 , 34 ) and free of the auxiliary liquid through the plane of its clamped edge region ( 31 ) between two defined final agen is back and forth, and the deflection of the membrane ( 10 , 11 ) at the operating pressures by at least one fabric layer ( 37 ) of the membrane ( 10 , 11 ) is limited to an area between the two end positions, which is not necessarily must be achieved. 2. Pump according to claim 1, in which a compensating vessel ( 38 ) is provided with a movable membrane ( 10 , 11 ) clamped on the edge in a housing ( 39 ), which has a compensating primary chamber ( 40 ) from a compensating secondary chamber ( 41 ) separates, the compensating primary chamber ( 40 ) is filled with a prestressed medium and the compensating secondary chamber ( 40 ) on the pressure line ( 19 ) is closed, characterized in that the membrane ( 10 , 11 ) a freely movable preforming ( 33 , 34 ) and the membrane ( 10 , 11 ) without stretching and under the influence of the media in the compensating primary chamber ( 40 ) and compensating secondary chamber ( 41 ) through the plane of its clamped edge area ( 31 ) between two defined end positions can be put up, and the deflection of the membrane ( 10 , 11 ) at the pressures occurring during operation is limited by at least one fabric layer ( 37 ) of the membrane to a region between the two end positions, that do not necessarily have to be achieved. 3. Pump according to claim 1 or 2, wherein the deformation has a spherical cap ( 34 ) or a double S shape. 4. Pump according to claim 3, wherein the preforming on the outer edge of the spherical cap ( 34 ) or double S-shape has an opposite curved connection area ( 33 ) to a flat edge area ( 31 ) of the membrane. 5. Pump according to one of claims 1 to 4, in which on both sides of the tissue layer ( 37 ) an impermeable membrane system ( 35 , 36 ) is arranged. 6. Pump according to one of claims 1 to 5, wherein the fabric layer ( 37 ) made of plastic, in particular polyester or polyamide. 7. Pump according to one of claims 1 to 6, in which at least one further membrane system ( 35 , 36 ) is made of elastomer, in particular a synthetic or natural rubber. 8. Pump according to one of claims 1 to 7, wherein the primary chamber ( 8 , 9 ) or secondary chamber ( 12 , 13 ) is connected to a safety valve and devices for determining the differential pressure of the primary chamber and secondary chamber and opening the safety valve when exceeded an allowable differential pressure are provided. 9. Pump according to one of claims 1 to 8, wherein the primary chamber ( 8 , 9 ) via a valve device ( 22 , 23 ) with a reservoir ( 28 ) with auxiliary liquid speed is connected, in the primary chamber ( 8 , 9 ) a button ( 20 , 21 ) is arranged, the membrane ( 10 , 11 ) actuating the button ( 20 , 21 ) during the suction stroke of the piston ( 1 ) on the way to its end position and a control device ( 24 , 26 ) actuating the valve device ( 20 , 23 ) when the button is pressed and the liquid deficit in the primary chamber ( 8 , 9 ) opens.