DE20311304U1 - Double-diaphragm, precision dosing, pump of miniaturized construction for laboratory use. - Google Patents

Abstract

Pumping chamber (211) and valve chambers (210,212) are each separated by the elastic diaphragms (204,202) into a process compartment (230,231,232) and a control compartment (220,221,222) which is connected to an a separate, external control unit (100,115). The control system, which is programmable to allow discontinuous dosing, operates via electro-pneumatic valves (111,112,113,114); alternatively, the motive fluid may be hydraulic fluid (claimed). The pump body comprises at least three rigid plates (201,203,205) between which are sandwiched the two elastomeric diaphragms (204,202), which may be of silicon rubber, Viton, Teflon or EPDM (claimed).

Description

In chemical research laboratories, chemical reactions are carried out in 100 ml glass vessels. For such reactions, the additional equipment required and thus the equipment costs for an experimental setup must be kept as low as possible. For a continuous or discontinuous experimental system, dosing and feed pumps are required that are very compact, resistant to clogging and can reproducibly dose small amounts of substances in the range of less than 1 ml per minute. In the laboratories, different reactions are carried out at short intervals, which changes the test conditions and also the chemicals used, so that many substances with different properties must be dosed precisely with one type of pump if possible. The dosing accuracy of the pumps is essentially defined by the short-term accuracy. The substances to be dosed must be dosed reproducibly at short intervals (seconds or minutes) with little error.

In particular, well-known piston or diaphragm pumps are used for such tasks. These pump types are oscillating displacement pumps. These pumps work according to the displacement principle and are equipped with check valves on the pump suction and pressure side. A change in the dosing quantity is made by varying the piston or diaphragm stroke, so that a changed dead space volume is created in the pump head depending on the set stroke. The check valves have a decisive influence on the pump function and the

Dosing accuracy of the pumps.

This means that reproducible dosing of the smallest liquid quantities depends directly on the functionality of the pump valves that come into contact with the product. The opening and closing function of the valves depends on the density and viscosity of the substance to be pumped, which is why reproducible and substance-

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Independent closing or opening is not guaranteed and dosing deviations occur, especially within short periods of time (short-term accuracy). Furthermore, the path of the closing body in the check valves is not linear, for example the spherical closing body describes a wobbling movement until it lies in the sealing seat and blocks the passage of the substance. It is known that ball check valves are preferably used in piston and diaphragm pump heads. The change in pump performance occurs by changing the stroke, so that the pistons or diaphragms no longer travel the maximum stroke and the suction behavior is therefore also impaired.
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In particular, when dosing liquid substances with different viscosity and/or density, a dependent closing time of the check valves is always initiated, which leads to an increase in the dosing error.

The well-known piston and diaphragm pumps are driven by a gear with a cam or eccentric shaft. The direct coupling of these pumps with the drive results in large device dimensions, the design of which is too large for many miniaturized test systems. The mechanical drives must be manufactured precisely and increase the investment costs. Pulsating displacement pumps are also equipped with magnetic drives. This means that the dimensions of these pump types are slightly smaller and the pumps have a constant dead volume in the pump head.

Microsystem pumps are known that can pump very small amounts of liquid. The micropumps are so-called precision pumps whose function is no longer guaranteed if the product is even slightly contaminated. The flow channels and displacement chambers within the micropump heads have dimensions of just a few μm. Contaminated products immediately clog flow channels or block the dynamically moving pump parts, so that a dosing process can be quickly interrupted. Small product channels allow

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conveying and dosing of viscous substances is not possible because the pressure loss is too great.

Various micro-diaphragm pumps are known which have very small structural dimensions due to piezoelectric or thermo-pneumatic drives and can therefore dose small amounts of substance. The patent DE 4402119 C2 describes a micro-diaphragm pump which is also thermally driven. These drive systems always work according to the principle of a thermally initiated volume expansion on one side of the diaphragm, so that the pump's delivery diaphragm creates a pumping effect through the deflection. These drive systems cannot overcome large differential pressures, for example to dose a liquid substance into a container under higher pressure. Furthermore, these pumps tend to become clogged, so that their operational use in chemical laboratories is unsatisfactory and such pumps are not used in preparative chemical laboratories.

Microsystem pumps, so-called gear pumps, operate at high speeds and generate pressure in the annular gap. During the pressure build-up in the discharge area of the pump, a backflow occurs into the suction area, particularly due to the mechanical tolerances of the rotor and stator of the pump, so that the pump efficiency is greatly reduced. Due to the low drive power of the microsystem pumps, the reproducible dosing of low-viscosity substances against high pressure is generally not guaranteed.

The invention is therefore based on the object of developing a pump which is highly miniaturized, which pumps small volumes, e.g. from 5 μη to 1000 μη/stroke and per unit of time, and which has a high short-term dosing accuracy. The pump should have good suction characteristics and pump against pressure, so that pumping against pressure is possible even when the pump head is not flooded.

Dosing substances with different densities should not have a significant impact on the conveying accuracy and dosing behavior. The fault-prone

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The risk of blockages caused by product contamination should be significantly reduced so that additional fine filters on the suction side of the pump are not required. The required suction and pressure valves on the pump head should open and close reproducibly, regardless of density, and should be tight against gas pressure, particularly when closed, so that there is no backflow during pumping, a high level of efficiency is achieved and precise pumping against pressure is thus possible. The dosing capacity of the volume flows to be pumped must be easy to adjust or vary and should in particular be up to 10 μ�I/stroke. The pump should be able to be manufactured inexpensively from a variety of resistant materials, particularly due to the different corrosion requirements in the chemical industry. Due to the occasionally harsh operating conditions, repair and maintenance should be simple and inexpensive.

Furthermore, investment advantages compared to the state of the art should be clearly visible. The design of the control or drive technology should not influence the pump head size and the possibility of integration into a miniaturized test system. The pump should be modular so that the dosing pump can be easily modified by adding or replacing module parts. The dosing performance should be changed without the displacement path of the membrane or piston in the pump head increasing the dead volume, so that the volume of liquid sucked in is completely displaced from the pump head at all times.

The object was achieved according to the invention by a modular, lamella-like, pneumatically driven pump head, which consists of at least three rigid lamellae (plates) and in the area of the individual parting plane of the middle plate and the adjacent neighboring plates at least one concave depression is present and each depression is completely covered by an elastic membrane and the membrane is part of the product chamber of the pump on one side and the other side is part of the control chamber. The depressions one-

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or on both sides of the membrane form the maximum distance by which the elastic membrane can be deflected.

The invention relates to a diaphragm pump with a multi-part pump body, comprising at least three rigid plates and one elastic diaphragm each arranged between these plates, wherein the plates form at least one pump chamber and at least two shut-off chambers, in particular in a spatial form of a truncated spherical section of a spherical zone (calotte), cylinder or cone, each with an inlet and an outlet opening for the material to be pumped, and the pump and shut-off chambers are connected to one another via connecting channels and, together with an inlet channel, the connecting channels and an outlet channel, form a passage channel, characterized in that the pump and shut-off chambers are each divided by the diaphragms into a product chamber and a control chamber and the control chambers have control lines which are connected to a control unit.

With pneumatic control, the control chamber is connected, in particular via a channel that runs through the respective outer plate, to e.g. an electro-pneumatic control unit that has e.g. a vacuum generator in a secondary line, in order to enable alternating pressure or vacuum loading of the control chamber. It is also possible to use a hydraulic fluid to apply pressure and tension to the control chamber. According to a control program that has at least four control steps that run one after the other, each with its own timer, the membranes in the pump and shut-off chambers are deformed, for example, so that the control or product chamber alternately increases or decreases. The membrane simultaneously opens or closes the inlet and outlet openings of the chambers in the membrane area, so that during the closing process at least the feed channels that come into contact with the product are tightly closed and, with a given control, at least one of the membranes in the direction of flow produces a reproducible volume displacement.

The control unit is particularly suitable due to the required miniaturization

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grades are arranged decentrally and, in the case of pneumatic control, are connected to the pump head e.g. with flexible hoses.

The control unit here is understood to be a combination of electronic control and actuators, e.g. electro-pneumatic switching valves that are mounted on a compressed air/vacuum distributor that has a pneumatic vacuum generator in a secondary line. The electronic control and the actuators can, for example, be mounted together in a housing. The electro-pneumatic valves are operated using a control program in order to carry out a precise sequence of work steps for the pumping process.

In particular, the shut-off and pump chambers are sealed at the edges by the inserted and pressed membranes.

A preferred design is one in which each shut-off and pump chamber has an individually assigned membrane and the membranes are inserted between the plates. The membranes are clamped in place by screwing the plates together, for example, in order to tightly seal the pressurized control and product chambers from the outside in the separation planes of the plates.

Clamping the membranes between the plates has advantages for the user in the event of repairs, so that in the event of a defect in the pump head, only the small part of the membrane needs to be replaced, saving considerable material costs. Assigning the part of the membrane to the respective chamber enables standardized membrane production and reduces production

cost.

A preferred embodiment of the pump has a groove at least in the product space of the pump chamber, which connects the apex of the pump chamber with the outlet opening of the pump chamber.

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The connecting groove from the apex to the outlet opening of the pump chamber increases the accuracy and reproducibility of the conveying process by ensuring that the dosing volume is completely drained. The groove forms a drainage collecting channel for the dosing material and compensates for differences in the deformation of the elastic membrane. There must be a surface between the inlet of the chamber and the groove so that the membrane can seal the inlet opening of the chamber to the groove. In the simplest design, the groove can be an elongated channel, but the groove can also have a branched contour in the recess.

In a further preferred embodiment of the pump, the control pressure on the membrane in all control chambers can be set at least 0.1 bar higher than the prevailing pressure at the outlet channel, preferably the control pressure is at least 0.5 bar higher and particularly preferably the control pressure is 1 bar higher than the pressure at the outlet channel.

The higher differential pressure between the outlet channel and the control side pressure ensures that the respective inlet openings in the chambers are tightly closed by the membrane.

The membranes preferably consist of an elastic material, in particular an elastomer, silicone, Viton, Teflon or an EPDM rubber.

A preferred embodiment of the pump in which several shut-off chambers have a common diaphragm is particularly advantageous.

A preferred embodiment of the diaphragm pump is characterized in that the pump consists of at least three plates and the pumping and shut-off chambers are formed by recesses in the plates.

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In a particularly preferred design, the pump consists of at least three plates and the pumping and shut-off chambers are formed by recesses in a central plate.

Another particularly preferred form of the diaphragm pump is characterized in that the pump consists of at least three plates and the pumping and shut-off chambers are formed by recesses in the outer plates.

In a preferred embodiment, the wall of the control chamber opposite the diaphragm has, at least in the pump chamber, a compensating volume, in particular a flat depression, into which the diaphragm nestles when there is negative pressure in the control chamber.

In a particularly preferred embodiment of the diaphragm pump, the compensation volume is at most 100% of the respective associated product space volume, preferably the compensation volume is at most 20%, and particularly preferably the compensation volume is at most 10% of the product space volume.

Typically, the product spaces of the shut-off chambers are smaller than the product space of the pumping chamber.

The center distance of the adjacent inlet and outlet of each pumping or shut-off chamber is two to ten times the largest hydraulic diameter of the respective inlet or outlet opening, preferably the center distance is two to five times and particularly preferably two to three times.

The defined center distance is an important functional dimension of the chambers. It ensures that the inlet and outlet channels or openings are tightly closed and

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increases the reproducible conveying of gaseous or liquid substances and influences the degree of miniaturization.

In a preferred embodiment, the connecting channels between the pump chamber and the shut-off chambers are straight and have a ratio of channel length to the respective hydraulic diameter of the channels of at most 20, preferably at most 10, particularly preferably at most 5.

The small dead space volume between the pump and shut-off chambers improves the suction performance of the pneumatic pump.

The plates of the diaphragm pump are preferably detachably connected to each other for cleaning and repair purposes.

A decentralized electro-pneumatic control unit preferably also enables synchronous control of several pump heads, so that only one control unit is necessary when several pumps are operated in parallel.

The diaphragm pump according to the invention with a decentralized electro-pneumatic control unit enables economical use with low investment costs in the research sector. This is particularly evident when changing tasks require different flow rates that cannot be covered by one pump head type. If the flow rates are different, only the pump head needs to be replaced, while the control part remains unchanged. The pump head is replaced by simply disconnecting the pneumatic control lines.

The control for conveying with the diaphragm pump is preferably carried out in such a way that a delivery stroke consists of at least four individual control steps following one another and each individual control step is connected to an intermediate constant or variable time element for the following control step.

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is separated and the delivery or dosing capacity of the pump can be changed by changing at least one timer.

The timing elements interwoven between the control steps ensure that the pneumatically triggered partial steps of the pump stroke are carried out precisely and completely and that the individual steps are reproducible. The synchronous changing of all timing elements to regulate the delivery rate ensures simple, user-friendly handling of the pump.

The time elements belonging to the control are preferably T > 0.1 seconds to 100 seconds, preferably the range is T > 0.3 seconds to 30 seconds and particularly preferably the time element is T > 0.5 seconds to 10 seconds.

The timing elements ensure that the fast electronic control signals (signal runtime) outpace the slower pneumatic working processes for deflection

of the membranes and thus the hydraulic displacement processes on the side of the membrane that comes into contact with the product are not prematurely terminated. Particularly when viscous substances are conveyed, the fluid dynamic processes require more time than the electronically triggered signals from the control system.
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The dosing cycle preferably consists of at least four control steps and has at least two different time elements, of which only one time element is variable and is used to regulate the pump cycle.

To optimize the pumping cycle of a pump according to the invention, the pneumatic opening and closing processes of the membranes in the shut-off chambers can be provided with a non-adjustable smaller timer and a variable timer can be used for the OPEN / CLOSED switching of the middle larger pumping chamber.

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Two different time elements are particularly advantageous when the volume of the shut-off chambers is smaller than the volume of the pump chamber.

In a particularly preferred mode of operation, each timer is longer than the required switching time of the associated electro-pneumatic multi-way valves.

Preferably, at least two diaphragm pumps are connected in parallel to the electronic and electro-pneumatic control units.

An electro-pneumatic control unit can control several diaphragm pumps in parallel, so that the pumps, which may have pump chambers of different sizes, can synchronously dose different substances in different quantities at the same time.

The thickness of the elastic membrane is preferably greater than 0.1 mm and less than 5 mm and the height of the pumping and shut-off chamber in the region of the apex of the chamber (largest extent above the membrane) is in particular greater than 2 times the membrane thickness and less than 10 times the membrane thickness.

The concave recesses in the plates can have various geometric shapes, such as a cylinder, a segment of a sphere or a truncated cone.

The diaphragm pump preferably has smaller recesses for the suction and pressure side shut-off chambers than for the pump chamber, and all recesses are arranged entirely on the product side of the diaphragm side in the middle plates.

A variant of the diaphragm pump preferably consists of a pneumatically controlled pump chamber, combined with two solenoid-operated valves as shut-off

chambers.

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The membranes used in the pump are preferably designed to be at least 20% larger in diameter than the diameter of the chambers formed in the separation plane of the plates.

In a further alternative preferred embodiment, metallic membranes are used as pump membranes and are inserted or permanently welded to one of the partial plates, in particular an outer plate.

In another special embodiment, a pulsation damper is installed in the flow direction behind the pressure-side shut-off chamber, in particular in the area of the outlet channel of the diaphragm pump.

In another special embodiment, the diaphragm pump is equipped with an integrated spring-loaded overflow valve to create an internal product circuit in the diaphragm pump. If the connected control pressure is greater than the desired pump pressure, an integrated relaxation option is created from the pump pressure side to the pump suction side.

In a further particularly preferred embodiment, at least two pump units, consisting of two pump chambers with associated four shut-off chambers, are arranged in the three rigid plates to form a double diaphragm pump head.

The invention also relates to a pump set consisting of two or more diaphragm pumps, wherein the diaphragm pumps according to the invention have a common control unit.

Preferred is a pump set in which the diaphragm pumps have common continuous plates.

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With the diaphragm pump according to the invention with controllable intake and pressure valve or intake-side and pressure-side shut-off chamber, very small volume flows of <5μ1 / stroke down to the ml range per minute can be conveyed reproducibly, depending on the design size. The separate structure between the actual pump unit or pump head and the decentralized electrical or electro-pneumatic control unit is particularly advantageous, as the space required for a continuously operating conveying device in a highly miniaturized test facility for screening work is very small. This pump principle works without mechanical gear and the required components of the pump head have no dynamic function, apart from the deflection of the diaphragm in the area of the shut-off and pump chamber, so that even for a miniaturized design of the pump components, no precision manufacturing is necessary. Mechanical interference is not present due to the lack of mechanical parts and the manufacturing costs for this reproducibly operating diaphragm pump head are significantly minimized. The pump only needs a power supply and a compressed air supply to work; these are available in every laboratory.

The use of the diaphragm pump is particularly advantageous for dosing very small amounts of liquid substances whose volume per pump stroke is significantly less than the specific drop size. By quickly applying the pneumatic conveying energy to the control side of the displacement diaphragm of the pump chamber, the sucked-in product volume in the pump chamber is ejected from the product space of the chamber and the outlet channel and no drops form at the pump discharge point. This means that dosing of small amounts of liquid into a reaction mixture is not delayed and a synthesis process is started synchronously with the dosing.

The dosing of small amounts of substance at opposing pressure is very easy to carry out, since the membranes of the shut-off chambers and pump chamber are elastic and the inlet and outlet product channels close gas-tight in the CLOSED position of the chambers, so that the gas phase of a connected pressure vessel

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no substance is pushed back to the inlet side of the pump via the outlet side of the pump head and suction is not interrupted at normal pressure.

A further advantage over the state of the art is that due to the small dead space and the tight shut-off and pumping chamber, a sensitive product to be dosed is fed to the destination without a long residence time and backmixing.

There are advantages, particularly in comparison to microstructure technology, because the channel dimensions are large in relation to the dosing volume, making the pump less sensitive to contamination. Any disruption caused by product contamination, which can be noticed by an increasing dosing error or lead to the pump failing to dose, is greatly reduced due to the large product channels. Product contamination can be flushed through the relatively large product channels during dosing.

The extremely small hold-up of the pump head and the low dead space volume ensure good suction behavior and fast, reproducible dosing, especially in applications involving new pharmaceutical substances that are only available in small quantities in the early stages of development.

Setting small dosing flows is particularly easy because the dosing quantity is set at a constant displacement volume using an intermediate timer in the control system. This makes it very easy to change volume flows without counter-control.

The lamellar structure of the diaphragm pump with integrated controllable valves, which generates a pulsating dosing flow due to the pumping principle, makes it possible to equalize the dosing flow by multiplying the displacement unit and the valves, whereby the structural dimensions of the pump in the test system do not increase significantly.

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The user benefits from further operational advantages as the wearing parts that come into contact with the product can be replaced easily and inexpensively.

The invention is explained in more detail below with reference to the figures.

Figure 1 shows the schematic structure of a lamellar

pneumatic diaphragm pump with associated electro-pneumatic control unit and programmable electronic control as well as the connecting lines.

Figure 2 shows an example of a diaphragm pump in which depressions in the

middle plate and form the pumping and shut-off chambers.

Figure 3 shows a pump head with separately inserted elastic membrane

for each chamber.

Figure 4 shows an application where several pumps are connected to one control unit

are interconnected.

Figures 5, 5a show a double diaphragm pump with common plates.
Figure 6 shows a detail of a pump chamber with compensation volume in

the tax chamber.

Figures 7, 7a show the arrangement and design of the groove or the collecting channel in, for example, a pump chamber.

Figure 8 shows a pump with chambers in the outer plates.

Figures 9,9a show designs of the diaphragm pump with chambers in the inner plate.

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Examples example 1

Figure 1 shows a diaphragm pump 200 in cross-section with the associated control system 100 and housing as well as a pneumatic distributor 115. Electronic components and a freely programmable electrical control system are installed in the housing. A power supply line (not shown) is used to supply voltage to the electronic components. The housing has a display 101, an on/off switch 102 and several function buttons 103 to 109 with which the required parameters for the pumping sequence or for the pumping process can be entered, visually tracked and saved. The electronic control system 100 enables various operating variants, so that the button 103 can be used to switch to continuous operation and the button 104 to discontinuous operation of the pump. In particular, the discontinuous operation of the pump can be set using a preselectable number of pump strokes and saved in the control system using button 105. Button 106 is used to reduce the set parameters, button 107 is used to increase the variable parameters, which can then also be saved in the control system as newly selected operating parameters of the diaphragm pump using button 105. In continuous operation, buttons 106 and 107 can be used to change the time constants. Button 108 allows the choice between internal and external control, for example from an external process control system. Pump 200 starts to work when button 109 is pressed, and if button 109 is pressed again, the work process is stopped again. At the start of dosing, the electronics with the programmable control sends digital signals via electrical connecting cables 110 to the electro-pneumatic 2/3-way valves 111, 112, 113, 114, which then switch to their defined open or closed position (Table 1). The electro-pneumatic 2/3-way valves 111 to 114 are mounted on a pneumatic distributor block 115. The distributor block has two supply channels 116, 117. The supply channel 116 is directly connected to the pressure

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air supply and the distribution channel 117 is connected to the vacuum supply by a vacuum line. The vacuum is generated by the vacuum generator 118 installed in the bypass, an injector, which is constantly supplied with compressed air by the valve 114 when the electrical control is switched on. In a compact design, the distribution block 115 with the electro-pneumatic 2/3-way valves and the vacuum generator 118 is located directly in the housing of the control 100, so that the compressed air supply of the supply channel 116 is connected via a hose coupling 110' and the pump head via the hose couplings 119', 120\ 12&Ggr;. The freely programmable electronic components, diodes for the optical function display, electrical power supply unit and an electrical circuit board are not shown in Figure 1.

The freely programmable control of the pneumatically operated diaphragm pump 200 switches the electro-pneumatic 2/3-way valves 111 to 114 and directs the pneumatic pressure in the channel 116 (pressure channel) or the vacuum in the distribution channel 117 (vacuum channel) in the distribution block 115 through the control lines (capillaries or hoses) 119, 120, 121 to the pneumatic control chambers (pneumatic chambers) 220, 221, 222 in the pump 200.

The valve 111 (Vl) is connected to the intake valve (lower shut-off chamber 210) of the diaphragm pump 200 via the control line 119. The other valve 112 (V2) (upper shut-off chamber 212) and valve 113 (V3) are connected to the pump chamber 211 of the pump 200 in the same way. The valve 114 (V4) constantly supplies the vacuum generator with compressed air and is switched immediately as soon as the electronics are supplied with electrical voltage.

The diaphragm pump head 200 consists of the three partial plates 201, 203, 205 and has inserted elastic diaphragms 202, 204, which are pneumatically deformable in the area of the pump chamber 211 and shut-off chambers 210, 212. The diaphragms 202, 204 have the same surface area as the plates 201, 203, 205 in order to ensure a good seal against the atmosphere. In the plates 201, 203, 205 there are recesses

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which form the pumping or shut-off chambers 210, 211, 212. The shut-off chambers 210, 212 are here, for example, incorporated into the plate 201 and the pumping chamber 211 is incorporated with a small compensating volume proportion in the plate 205 and with the larger volume proportion in the middle plate 203.
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For example, the shut-off chamber 210 is the name given to the controllable suction valve of the pump head. Accordingly, the pump chamber 211 represents the delivery chamber and the shut-off chamber 212 represents the controllable pressure valve of the pump head.

The membranes 202, 204 divide the pumping and shut-off chambers into control chambers 220, 221, 222 and product chambers 230, 231, 232.

The pumping or shut-off chambers 210, 211, 212 have the shape of truncated cones. The middle plate 203 has an intake channel 207 and an outlet channel 206. Both channels 206, 207 are each extended by a welded-in capillary. The channels 209, 208 connect the product spaces 230, 231, 232 of the chambers 210, 211, 212 with each other.

The pump chamber 211 has a groove 213, as a connecting element from the deepest geometric point of the recess in the plate to the outlet opening or

Connecting channel 209. It is also made clear that there is still a sufficiently large distance between the inlet channel 208 and the beginning of the outlet channel 209 with the connecting groove 213 to enable the openings in the product space of the pump chamber to be tightly closed by the membrane 204.
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The diaphragm pump 200 is shown here in control step 4 (see Table 1). In the area of the shut-off chamber 210 (controllable intake valve), the diaphragm 202 is pressurized on the control chamber side 220, so that the diaphragm 202 blocks the intake channel 207 at the inlet 240 (Fig.2) and the connecting channel 208 at the outlet 241 (Fig.2). In the area of the pump chamber 211 (delivery chamber or displacement unit), the associated control chamber 221 is pressurized with vacuum, so

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that the membrane area lifts off and opens the supply and discharge connection channels 208, 209. The shut-off chamber 212 is also subjected to vacuum on the control side, so that the connection channel 209 and the outlet channel 206 are opened in order to displace the pump stroke volume from the pump chamber in the following control step 5 (see Table 1). The screws required for pulling the plates together and simultaneously pressing the inserted membranes are not shown in Figure 1.

The sequence of the programmable control steps and the position of the valves 111 to 114 are shown in Table 1 below. The digital signal "1" means that compressed air is present (result: the membrane is pressed against the plate 203 and closes) and the signal "0" means that vacuum is present (the membrane is raised in the control chamber and opens). As soon as the electronic control is supplied with electrical voltage and switched on with the button 102, the programmed control switches the valves 111 to 114 to a defined start or basic position. The control of a complete pump stroke here, for example, consists of five individual steps. If the pumping process is interrupted or ended, the control jumps to the start or basic position.

Table 1

Step Vl (111)
Suction valve V3 (113)
Displacer V2 (112)
Pressure valve V4 (114)
vacuum initial position 1 1 1 1 1st step 0 1 1 1 Step 2 0 0 1 1 Step 3 1 0 1 1 Step 4 1 0 0 1 Step 5 1 1 0 1 Back to step 1

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In the control sequence, a variable timer is programmed behind each control step 1 - 5 (not shown in Table 1) so that the individual control steps that run one after the other do not influence each other and are carried out completely. The switching times of the electro-pneumatic valves are longer and therefore significantly slower than the time required to send the digital signals. The intermediate timers ensure that the pump function is carried out reproducibly and completely in accordance with the control cycle 1-5 (see Table 1).

Example 2

Figure 2 shows a diaphragm pump similar to the pump described in Figure 1, but the chambers or recesses 210', 211', 212' are located in the middle plate 203\. The chambers 210' to 212' here have the shape of a spherical segment. It can be seen that the height at the apex of the recess of the pump chamber is greater than the thickness of the diaphragm. In this design, the center distance of the inlet and outlet channels 207, 208 on the suction side of the pump (chamber 210") is greater than the center distance of the inlet and outlet channels 209, 206 of the pressure valve (chamber 212'). The larger center distance on the suction valve increases the tightness of the suction valve and prevents backflow of the product during the pumping process.

Example 3

Figure 3 shows a variant of the pump 200 from Figure 2 with three separately inserted membranes 300, 301, 302. The recesses 210', 211', 212' are all arranged on the inner plate 203' and form the product chambers 230, 231, 232 with the membranes 300, 301, 302. When the product channels are open, the membranes 300, 301, 302 rest against the respective outer plates 201', 205'. These membranes are operated via the control chamber side via a hole according to the control

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program is pressurized with compressed air or vacuum to ensure the pumping function.

Figure 4, for example, shows the parallel operation of three diaphragm pumps 200a, 200b, 200c of the type shown in Figure 3 in the non-controlled state. These are connected in parallel to the lines of the pressure distributor 115, similar to Figure 1. The pneumatic 2/3-way valves of the pressure distributor 115 are actuated by means of the electrical control (not shown here) and actuate the diaphragms via the control lines 119 to 121, which are branched here and connected to the three pump heads. When operating the pump heads in parallel with a control unit, care must be taken to ensure that the connecting lines and the compressed air and vacuum supply are sufficiently dimensioned.

Figures 5 and 5a show an embodiment of the diaphragm pump 200d in which two pump units or two pump heads have common sub-plates. The sub-plates are clamped together with the screws 500. The essential contours such as pump chambers and connecting channels inside the pump head are shown in broken lines in Figure 5a. The double pump head can be operated with a control unit so that with one control stroke (corresponding to steps 1-5; Table 1, Fig.l) twice the delivery quantity can be metered per stroke.

Another use is when pump chambers of the same or different sizes are incorporated into the partial plates, so that two different substances are pumped synchronously with one control unit, or two control units for generating different material flows are connected to the common pump head. The internal structure of a single pump unit corresponds to the pump according to Figure 3. Fig. 5a clearly shows that the outer contours (501, 502, 503) of the chambers in the different levels of the plates overlap in order to ensure a small dead space volume and thus good output behavior of the pump. Furthermore, a particularly compact pump head design is possible.

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Figure 6 shows a cross-section of two sections of the plates 203, 205 in the area of the pump chamber 211 of a diaphragm pump similar to Figure 1. The volume of the pump chamber is distributed equally between both plates, so that the inserted diaphragm 301 is clamped over a concentric sealing surface 214 and seals the product chamber 231 and the control chamber 221 to the outside.

Figure 7, 7a shows the top view of the recess in a diaphragm pump in the form of a spherical segment geometry of the pump chamber 211. The groove 213 provided can be seen, which runs from the apex of the pump chamber to the connecting channel 209 and serves as a collecting channel for completely emptying the product space. Figure 7a shows another special design of a branched groove 213" or the collecting channel 213.

Example 5

Figure 8 shows the diaphragm pump head 200 according to the invention with a pump chamber 211" and two shut-off chambers 210", 212" and the elastic diaphragm 202" and 204" inserted between the plates 201", 203", 205". In this embodiment, the diaphragm pump has recesses in the outer plates 201", 205" and the collecting channel 213" is located in the plate 203".

The inlet channel 207", the connecting channels 208", 209" and the outlet channel 206" as well as the collecting channel 213" can be seen. This embodiment of the pump according to the invention requires less manufacturing effort.

Figure 9 shows a combined arrangement of the connecting channels of the pump head. The middle plate is shown in a sectional view and the outer plates 20', 205' can be made smaller due to the arrangement of the passage channel. The inlet channel 207' and connecting channel 208' between the pump chamber and the suction-side shut-off chamber are placed at right angles to the outer plate contour, so that the connecting channel 208' is straight and short. The dead-

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The volume of the connecting channel 208' is thereby minimized. The connecting channel to the pressure-side shut-off chamber has a greater length and a larger dead space volume. This design requires a third reduced plate 205' for the construction of the pump.

Figure 9a shows an optimized pump with a low dead space volume, with the middle plate 203' shown in a sectional view. The geometric surfaces of the recesses of the shut-off chambers lie partially or completely in the shadow of the geometric surface of the pump chamber recess, so that the connecting channels from the pump chamber to the shut-off chambers are extremely short and an optimized suction behavior of the pump is made possible.

In Figure 9a, the connecting channel 209' is positioned at the apex of the pump chamber recess from the pump chamber 21' to the pressure-side shut-off chamber 212', so that the collecting channel (see Figure 7) is omitted. The dead space volume of the pump is formed from the volume of the two connecting channels 208', 209'. The chamber volume of the suction-side recess of the shut-off chamber 210' lies partially and the chamber volume 212' lies completely in the shadow of the pump chamber recess 21', so that the connecting channels 208', 209' are designed to be extremely short while optimizing the thickness of the middle plate 203'. The ratio of channel length 208' to diameter is 3.5.

The resulting geometric surfaces of the depressions of the shut-off chambers on the respective levels of the plates lie partially or completely in the shadow of the forming geometric surface of the pump chamber depression, so that the connecting channels of the chambers and the dead space volume of the pump head are extremely reduced.

Claims (18)

1. Diaphragm pump with a multi-part pump body, comprising at least three rigid plates ( 201 , 203 , 205 ) and at least two elastic membranes ( 204 , 202 ) arranged between these plates ( 201 , 203 , 205 ), wherein the plates ( 201 , 203 , 205 ) form at least one pump chamber ( 211 ) and at least two shut-off chambers ( 210 , 212 ), in particular in the geometry of a spherical section, a spherical zone, a cylinder or a truncated cone, each with an inlet ( 240 ) and an outlet opening ( 241 ) for the material to be pumped, and the pump chamber ( 211 ) and shut-off chambers ( 210 , 212 ) together with an inlet channel ( 207 ) are connected to the connecting channels ( 208 ) and ( 209 ) and an outlet channel ( 206 ) form a passage channel, characterized in that the pump chamber ( 211 ) and the shut-off chambers ( 210 , 212 ) are each separated by the membranes ( 204 , 202 ) into a product chamber ( 230 , 231 , 232 ) and a control chamber ( 220 , 221 , 222 ) and the control chambers ( 220 , 221 , 222 ) have control lines ( 119 , 120 , 121 ) which are connected to a control unit ( 100 , 115 ). 2. Diaphragm pump according to claim 1, characterized in that the pump has a groove ( 213 ) in the product chamber ( 231 ) which runs from the apex of the product chamber to the outlet opening. 3. Diaphragm pump according to claim 1 or 2, characterized in that the pump chamber ( 211 ) and the shut-off chambers ( 210 , 212 ) are sealed at the edges by the diaphragms ( 204 , 202 ). 4. Diaphragm pump according to one of claims 1 to 3, characterized in that the diaphragms ( 204 , 202 ) consist of an elastic material, in particular an elastomer, silicone, Viton, Teflon or an EPDM rubber. 5. Diaphragm pump according to one of claims 1 to 4, characterized in that the shut-off chambers ( 210 , 212 ) have a common diaphragm ( 202 ). 6. Diaphragm pump according to one of claims 1 to 5, characterized in that the pump consists of at least three plates ( 201 , 203 , 205 ) and the pump chamber ( 211 ) and the shut-off chambers ( 210 , 212 ) are formed by recesses ( 210 ', 211 ', 212 ') in the plates ( 201 , 203 , 205 ). 7. Diaphragm pump according to claim 6, characterized in that the pump consists of at least three plates ( 201 , 203 , 205 ) and the pump chamber ( 211 ) and the shut-off chambers ( 210 , 212 ) are formed by recesses ( 210 ', 211 ', 212 ') in a central plate ( 203 '). 8. Diaphragm pump according to claim 6, characterized in that the pump consists of three plates ( 201 , 203 , 205 ) and the pumping chamber ( 211 ) and the shut-off chambers ( 210 , 212 ) are formed by recesses ( 210 ", 211 ", 212 ") in the outer plates ( 201 ", 205 "). 9. Diaphragm pump according to one of claims 1 to 8, characterized in that the center distance of the respectively adjacent inlet ( 240 ) and the outlet ( 241 ) of the pump chamber ( 211 ) or the shut-off chambers ( 210 , 212 ) is at least twice to ten times the largest hydraulic diameter of the respective inlet opening ( 240 ) or outlet opening ( 241 ). 10. Diaphragm pump according to one of claims 1 to 9, characterized in that the control chambers can be operated with air or hydraulic fluid. 11. Diaphragm pump according to one of claims 1 to 10, characterized in that the inlet channel ( 207 ) and the outlet channel ( 206 ) are connected to one another via a secondary line with an overflow valve. 12. Diaphragm pump according to one of claims 1 to 10, characterized in that the plates ( 201 , 203 , 205 ) are detachably connected to one another. 13. Diaphragm pump according to one of claims 1 to 12, characterized in that the wall of the control chamber ( 221 ) opposite the diaphragm ( 204 ) has a compensating volume, in particular a flat depression, at least in the pump chamber ( 211 ). 14. Diaphragm pump according to claim 13, characterized in that the compensation volume is at most 100%, preferably at most 20% and particularly preferably at most 10% of the associated volume of the product space ( 231 ). 15. Diaphragm pump according to one of claims 1 to 14, characterized in that the outer contours of the pumping and shut-off chambers are arranged superimposed in different planes. 16. Diaphragm pump according to one of claims 1 to 15, characterized in that the connecting channels between the pump chamber ( 211 ') and the shut-off chambers ( 210 ', 212 ') have a ratio of channel length to hydraulic diameter of at most 20 or at most 10, particularly preferably at most 5. 17. Pump set consisting of two or more diaphragm pumps according to one of claims 1 to 16, characterized in that the diaphragm pumps have a common control unit ( 100 , 115 ). 18. Pump set according to claim 17, characterized in that at least two diaphragm pumps have common continuous plates ( 201 , 203 , 205 ).